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1
Nagarajan, Balasubramanian, Sylvie Castagne, and Zhong Ke Wang. "Investigation of Copper Foil Thinning Behavior by Flexible-Pad Laser Shock Forming." Key Engineering Materials 535-536 (January 2013): 306–9. http://dx.doi.org/10.4028/www.scientific.net/kem.535-536.306.
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This paper reports on a novel microforming technique, Flexible-Pad Laser Shock Forming (FPLSF) which uses laser-induced shock waves and a flexible pad to induce plastic deformation on metallic foils. Thickness distribution at the cross-section of the craters formed by FPLSF is analyzed experimentally with respect to laser fluence, which is a significant process variable that controls the deformation pressure. Furthermore, hardness of the deformed samples at the cross-section is measured by nanoindentation testing. It is found that the thinning of copper foil by FPLSF ranges from 7% to 25% for laser fluence ranging between 7.3 J/cm2 and 20.9 J/cm2. Thinning is maximum at the crater center, which can be attributed to the maximum compressive stresses in the thickness direction, and minimum at the edge portions. With increase in laser fluence, thinning of the foil increases whereas minimum change in hardness is observed. The variation in thinning across different crater locations ranges between 6% and 8% only, which indicates that FDLSF can be developed as a competitive technique to produce components with uniform thickness distribution.
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Kon, Thomas M., Melanie A. Schupp, Hans E. Winzeler, and James R. Schupp. "Screening Thermal Shock as an Apple Blossom Thinning Method. II. Pollen Tube Growth and Spur Leaf Injury in Response to Temperature and Duration of Thermal Shock." HortScience 55, no. 5 (2020): 632–36. http://dx.doi.org/10.21273/hortsci14619-19.
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Blossom thinning can confer significant benefits to apple growers, including increased fruit size and annual bearing. However, current blossom thinning practices can damage spur leaves and/or fruit. We evaluated the use of short duration forced heated air treatments [thermal shock (TS)] as a blossom thinning strategy for ‘York Imperial’. Using a variable-temperature heat gun, TS treatments were applied to solitary blossoms 24 hours after pollination. Effects of output temperature (five levels) and treatment duration (four levels) were evaluated using a completely randomized design with a factorial treatment structure. Short duration treatments (0.5 and 1.0 seconds) were ineffective for arresting pollen tube growth in vivo. TS temperature required to inhibit stylar pollen tube growth was inconsistent across years. In 2014, TS temperatures ≥56 °C inhibited pollen tubes from reaching the style base at 2.0 and 4.0 second durations. However, in 2015, TS temperatures ≥81 °C at 4.0 seconds prevented pollen tubes from reaching the style base. Inconsistent effects of TS across years were attributed to treatments being applied too late due to optimal conditions for pollen tube growth during the intervening 24-hour period after pollination. Excessive injury to spur leaf tissue was observed at temperatures higher than 84 °C and 70 °C (2.0 and 4.0 seconds, respectively). Pollen tube growth was reduced or arrested at temperature and duration combinations that caused minimal visible injury to spur leaves. Identifying and exploiting structural differences between apple blossoms and vegetative spur leaves may provide insight for the future development of TS or other attempts at developing selective thinning technologies.
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OGASAWARA, Nagahisa, Norimasa CHIBA, Yoichi KAWASHIMA, Eiji KOBAYASHI, and Yuji KIKUCHI. "907 Shock Absorption Mechanism of Aluminum Honeycomb with Thinning Cell Wall." Proceedings of The Computational Mechanics Conference 2008.21 (2008): 71–72. http://dx.doi.org/10.1299/jsmecmd.2008.21.71.
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Koo, Jinmo, Tae-Gwon Son, Soo-Yeon Kim, and Kyeong-Yeoll Lee. "Differential responses of Apis mellifera heat shock protein genes to heat shock, flower-thinning formulations, and imidacloprid." Journal of Asia-Pacific Entomology 18, no. 3 (2015): 583–89. http://dx.doi.org/10.1016/j.aspen.2015.06.011.
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Bahrar, Tarek, Hassan Samri, and My Ehoussaine Ech-Chibat. "Numerical modeling of transient non Newtonian thinning fluid flow." E3S Web of Conferences 469 (2023): 00028. http://dx.doi.org/10.1051/e3sconf/202346900028.
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This study concerns a numerical simulation of transient non-Newtonian fluid flow in a hydraulic pipe resulting from sudden valve closure, commonly known as waterhammer or hydraulic shock. The fluid behaves as a law power model. The basic equations are solved numerically by the characteristic method to obtain average pressure and velocity across a right sections of pipe and, a flow velocity profile by a Runge–Kutta scheme of fourth-order. The results of the present model agree suitably with those found in the literature [1]. This study highlights the remarkable effects of the properties of this fluids on the pressure oscillations generated by hydraulic waterhammer compared to fluids of Newtonian behavior.
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Cha, Ji Hwan, and Maxim Finkelstein. "Information-based thinning of point processes and its application to shock models." Journal of Statistical Planning and Inference 142, no. 8 (2012): 2345–50. http://dx.doi.org/10.1016/j.jspi.2012.02.049.
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Zhang, Xiaoling, Qingduan Meng, and Liwen Zhang. "Dependence of the Deformation of 128×128 InSb Focal-plane Arrays on the Silicon Readout Integrated Circuit Thickness." Open Electrical & Electronic Engineering Journal 9, no. 1 (2015): 170–74. http://dx.doi.org/10.2174/1874129001509010170.
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The square checkerboard buckling deformation appearing in indium antimonide infrared focal-plane arrays (InSb IRFPAs) subjected to the thermal shock tests, results in the fracturing of the InSb chip, which restricts its final yield. In light of the proposed three-dimensional modeling, we proposed the method of thinning a silicon readout integrated circuit (ROIC) to level the uneven top surface of InSb IRFPAs. Simulation results show that when the silicon ROIC is thinned from 300 μm to 20 μm, the maximal displacement in the InSb IRFPAs linearly decreases from 7.115 μm to 0.670 μm in the upward direction, and also decreases linearly from 14.013 μm to 1.612 μm in the downward direction. Once the thickness of the silicon ROIC is less than 50 μm, the square checkerboard buckling deformation distribution presenting in the thicker InSb IRFPAs disappears, and the top surface of the InSb IRFPAs becomes flat. All these findings imply that the thickness of the silicon ROIC determines the degree of deformation in the InSb IRFPAs under a thermal shock test, that the method of thinning a silicon ROIC is suitable for decreasing the fracture probability of the InSb chip, and that this approach improves the reliability of InSb IRFPAs.
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Quaisie, James Kwasi, Wang Yun, Xu Zhenying, et al. "Experimental Study on Water-Jet Shock Microforming Process Using Different Incident Pressures." Advances in Materials Science and Engineering 2020 (July 9, 2020): 1–9. http://dx.doi.org/10.1155/2020/2365698.
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The purpose of this paper is to demonstrate a new process technology using the cavitation phenomenon, mainly a water-jet shock microforming, for the fabrication of a metallic foil. 304 stainless steel was exposed to a high-speed submerged water jet with different incident pressures and certain working conditions. In this experiment, a KEYENCE VHX-1000C digital microscope, confocal laser-scanning microscope (Axio CSM 700), and micro-Vickers hardness tester were utilized to observe the forming depth, surface quality, thickness distribution, and section hardness distributions under different incident pressures. The experimental results indicated that the surface morphology of the metal foils attained good geometrical features under this dynamic microforming method and there were no cracks or fracture. The forming depth and surface roughness increased with the incident pressure. In addition, the forming depth increased from 124.7 μm to 327.8 μm, while the surface roughness also increased from 0.685 μm to 1.159 μm at an incident pressure of 8 MPa to 20 MPa. Maximum thickness thinning of the formed foils occurred at the fillet region when the thickness thinning ratio was 21.27% under the incident pressure of 20 MPa, and there was no fracture at the bottom or the fillet region. The tested hardness indicated that during the cold-rolled state of the sample, the hardness sample increased slightly along the cross section of the formed region and the hardness of the annealed 304 stainless steel foils increased significantly along the cross-sectional region.
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Liu, Fei, Huixia Liu, Chenkun Jiang, Youjuan Ma, and Xiao Wang. "Experimental and Numerical Investigations of a Novel Laser Impact Liquid Flexible Microforming Process." Metals 8, no. 8 (2018): 599. http://dx.doi.org/10.3390/met8080599.
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A novel high strain rate microforming technique, laser impact liquid flexible embossing (LILFE), which uses laser induced shock waves as an energy source, and liquid as a force transmission medium, is proposed by this paper in order to emboss three-dimensional large area micro arrays on metallic foils and to overcome some of the defects of laser direct shock microembossing technology. The influences of laser energy and workpiece thickness on the deformation characteristics of the pure copper foils with the LILFE process were investigated through experiments and numerical simulation. A finite element model was built to further understand the typical stages of deformation, and the results of the numerical simulation are consistent with those achieved from the experiments. The experimental and simulation results show that the forming accuracy and depth of the embossed parts increases with the increase in laser energy and decrease in workpiece thickness. The thickness thinning rate of the embossed parts increases with the decrease of the workpiece thickness, and the severest thickness thinning occurs at the bar corner region. The experimental results also show that the LILFE process can protect the workpiece surface from being ablated and damaged, and can ensure the surface quality of the formed parts. Besides, the numerical simulation studies reveal the plastic strain distribution of embossed microfeatures under different laser energy.
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Logar, Andraž, Damjan Klobčar, Aleš Nagode, Uroš Trdan, Gregor Černivec, and Abhay Sharma. "Advanced Analysis of the Properties of Solid-Wire Electric Contacts Produced by Ultrasonic Welding and Soldering." Materials 17, no. 2 (2024): 334. http://dx.doi.org/10.3390/ma17020334.
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The current article presents an advanced analysis of the properties of solid-wire electric contacts produced with ultrasonic welding and soldering. Soldering is generally used to join thin, solid copper wires to produce electrical contacts in small-volume production, as ultrasonic welding does not provide acceptable peel force and tensile strength due to the deformation and thinning of the wires. In this article, ultrasonic welding of thin, solid copper wires using a ring before and after a thermal shock test is discussed and compared with the standard soldering technique. The thermal shock test was carried out in the temperature range from −30 to 150 °C. Half of the samples, for both the joining techniques and the wires, were subjected to the thermal shock test; the other half were not. Investigations included electrical resistance tests, optical and SEM microscopy, XRD, microhardness measurements, peel tests, tensile tests, and fractographic analysis. The electrical resistance test, microscopy, microhardness measurements, and fracture examinations showed no differences between the thermal shock-exposed and the non-exposed samples with the same joining process. In mechanical tests, the ultrasonic joint demonstrated superior strength compared to the soldered joint.
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Kitavtsev, G., M. A. Fontelos, and J. Eggers. "Thermal rupture of a free liquid sheet." Journal of Fluid Mechanics 840 (February 14, 2018): 555–78. http://dx.doi.org/10.1017/jfm.2018.74.
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We consider a free liquid sheet, taking into account the dependence of surface tension on the temperature or concentration of some pollutant. The sheet dynamics are described within a long-wavelength description. In the presence of viscosity, local thinning of the sheet is driven by a strong temperature gradient across the pinch region, resembling a shock. As a result, for long times the sheet thins exponentially, leading to breakup. We describe the quasi-one-dimensional thickness, velocity and temperature profiles in the pinch region in terms of similarity solutions, which possess a universal structure. Our analytical description agrees quantitatively with numerical simulations.
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CHERIET, MOHAMED, JEAN-CHRISTOPHE DEMERS, and SYLVAIN DEBLOIS. "SHOCK FILTER-BASED DIFFUSION FIELDS — APPLICATION TO GRAYSCALE CHARACTER IMAGE PROCESSING." International Journal of Image and Graphics 05, no. 02 (2005): 209–45. http://dx.doi.org/10.1142/s0219467805001732.
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In this article, the new concept of diffusion fields based on partial differential equations is applied to character image processing. Specific diffusion fields are developed according to character image structures and features, depending, on the scope of application. Doing so allows the application of a straightforward one-dimensional numerical scheme to image enhancement, erosion, dilation and thinning. The strength of this approach is the flexibility brought by the diffusion field, which can be defined taking into account specific difficulties of grayscale character images with a minimum of prior information. Thus, the application of the algorithm is shown to be robust to singularity points, the creation of spurious branches, variations in stroke thickness and intensity, multimodality, noise and image background patterns. The resulting enhanced images are noise free with sharp edges and the local typical intensity levels preserved. Thinned characters are connected skeletons located on the ridge of the initial character. Again, the typical intensity of the character and background are preserved.
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Meghoufel, A., G. Cloutier, N. Crevier-Denoix, and J. A. de Guise. "Tissue Characterization of Equine Tendons With Clinical B-Scan Images Using a Shock Filter Thinning Algorithm." IEEE Transactions on Medical Imaging 30, no. 3 (2011): 597–605. http://dx.doi.org/10.1109/tmi.2010.2089636.
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Yoon, Somy, Ulrich Gergs, Julie R. McMullen, and Gwang Hyeon Eom. "Overexpression of Heat Shock Protein 70 Improves Cardiac Remodeling and Survival in Protein Phosphatase 2A-Expressing Transgenic Mice with Chronic Heart Failure." Cells 10, no. 11 (2021): 3180. http://dx.doi.org/10.3390/cells10113180.
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Heat shock protein (HSP) 70 is a molecular chaperone that regulates protein structure in response to thermal stress. In addition, HSP70 is involved in post-translational modification and is related to the severity of some diseases. Here, we tested the functional relevance of long-lasting HSP70 expression in a model of nonischemic heart failure using protein phosphatase 2 catalytic subunit A (PP2CA)-expressing transgenic mice. These transgenic mice, with cardiac-specific overexpression of PP2CA, abruptly died after 12 weeks of postnatal life. Serial echocardiograms to assess cardiac function revealed that the ejection fraction (EF) was gradually decreased in transgenic PP2CA (TgPP2CA) mice. In addition, PP2CA expression exacerbated systolic dysfunction and LV dilatation, with free wall thinning, which are indicators of fatal dilated cardiomyopathy. Interestingly, simultaneous expression of HSP70 in double transgenic mice (dTg) significantly improved the dilated cardiomyopathy phenotype of TgPP2CA mice. We observed better survival, preserved EF, reduced chamber enlargement, and suppression of free wall thinning. In the proposed molecular mechanism, HSP70 preferentially regulates the phosphorylation of AKT. Phosphorylation of AKT was significantly reduced in TgPP2CA mice but was not significantly lower in dTg mice. Signal crosstalk between AKT and its substrates, in association with HSP70, might be a useful intervention for patients with nonischemic heart failure to suppress cardiac remodeling and improve survival.
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Salazar Castillo, Rodrigo O., Sterre F. Ter Haar, Christopher G. Ponners, Martijn Bos, and William Rossen. "Fractional-Flow Theory for Non-Newtonian Surfactant-Alternating-Gas Foam Processes." Transport in Porous Media 131, no. 2 (2019): 399–426. http://dx.doi.org/10.1007/s11242-019-01351-6.
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Abstract Foam can improve sweep efficiency in gas-injection-enhanced oil recovery. Surfactant-alternating-gas (SAG) is a favored method of foam injection. Laboratory data indicate that foam can be non-Newtonian at low water fractional flow fw, and therefore during gas injection in a SAG process. We investigate the implications of this finding for mobility control and injectivity, by extending fractional-flow theory to gas injection in a non-Newtonian SAG process in radial flow. We make most of the standard assumptions of fractional-flow theory (incompressible phases, one-dimensional displacement through a homogeneous reservoir, instantaneous attainment of local equilibrium), excluding Newtonian mobilities. For this initial study, we ignore the effect of changing or non-uniform oil saturation on foam. Non-Newtonian behavior at low fw implies that the limiting water saturation for foam stability varies as superficial velocity decreases with radial distance from the well. We discretize the domain radially and perform Buckley–Leverett analysis on each narrow increment in radius. Solution characteristics move outward with fixed fw. We base the foam model parameters and non-Newtonian behavior on laboratory data in the absence of oil. We compare results to mobility and injectivity determined by conventional simulation, where grid resolution is usually limited. For shear-thinning foam, mobility control improves as the foam front propagates from the well, but injectivity declines somewhat with time. This change in mobility ratio is not that at steady state at fixed water fractional flow in the laboratory, however, because the shock front in a non-Newtonian SAG process does not propagate at fixed fractional flow (though individual characteristics do). Moreover, the shock front is not governed by the conventional condition of tangency to the fractional-flow curve, though it continually approaches this condition. Injectivity benefits from the increased mobility of shear-thinning foam near the well. The foam front, which maintains a constant dimensionless velocity for Newtonian foam, decelerates somewhat with time for shear-thinning foam. For shear-thickening foam, mobility control deteriorates as the foam front advances, though injectivity improves somewhat with time. Overall, however, injectivity suffers from reduced foam mobility at high superficial velocity near the well. The foam front accelerates somewhat with time. Conventional simulators cannot adequately represent these effects, or estimate injectivity accurately, in the absence of extraordinarily fine grid resolution near the injection well.
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Zhang, Li Ming, Tian Ma, Hai Feng Li, and Yong Huang. "Preparation of Refractory Nozzle by Gelcasting of Zirconia Suspensions with Coarse Particles." Key Engineering Materials 280-283 (February 2007): 987–90. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.987.
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Zirconia suspensions with coarse particles were prepared and the rheogical behavior and sediment stability of such suspensions with different dispersants were studied. It was found that ZrO2 suspension stabilized with TAC (tri-ammonium citrate) has an obvious shear-thinning behavior and rapid settlement; In contrast, the suspension stabilized with arabic gum shows a shear-thickening behavior and hardly any settlement. Considering both fluidity and settlement stability, APA (ammonium-polyacrylate) was chosen as the dispersant to increase the solid volume fraction of ZrO2 suspension. Utilizing the above suspension, a kind of refractory nozzle for precision casting of a Cu-Cr alloy was prepared by gelcasting. Such nozzle has a very good resistance to thermal shock and flux scouring.
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Byers, R. E. "The Influence of Temperature and Low Light on Fruit Set and Chemical Thinning of Apple Trees." HortScience 33, no. 3 (1998): 452e—453. http://dx.doi.org/10.21273/hortsci.33.3.452e.
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Fruit trees grown in the eastern U.S. environment are typically exposed to low light conditions from cloudy/rainy periods that can reduce PAR to 10% to 15% of full sun for 2 to 3 days. To magnify or concentrate the effect of temperature during low light stress, fruit trees were moved from the field into total darkness for 2 to 4 days at various temperatures and then returned to the field. This provided low light stress while eliminating the need for treatments involving various levels of light and temperature during the day on photosynthesis. To reduce transplanting shock, bearing apple trees used were grown in the field in 25-cm-diameter root bags and were on M.27 rootstock. After initial fruit set (at about 15 mm fruit diameter) trees were dug and transplanted into 5-gal buckets and moved for short periods of time (2 to 4 days) into various dark environments or sprayed with various thinning chemicals and placed in growth chambers at 5, 10, 16, and 21 °C in the dark. Immediately after dark treatments, trees were returned to the field and placed in the original holes. In 1995, we found that Elstar/M.27 apple trees placed in the dark for 3 or 4 days and returned to natural sunlight conditions abscised all of their fruit at 21 °C dark temperature but were retained at 5 °C. In 1996, we found that Braeburn/M.27 apple trees placed in the dark for 2 days and returned to natural sunlight conditions abscised all of their fruit at 16 and 21 °C dark temperature, but were retained if the dark period was 5 °C. These data indicated that the dark period temperature was very important for fruit retention. In addition, trees sprayed with Carbaryl+Accel 3 h before placing in the growth chambers caused the development of more pigmy fruit at all temperatures. Pigmy fruit also appeared to be related to the combined effects of digging trees, treating with Carbaryl + Accel, and colder temperatures. In 1997, we found that Stayman/M.27 apple trees placed in the dark for 2 days and returned to natural sunlight conditions abscised most of their fruit at 21 °C dark temperature, but were retained if the dark period was 5 °C. Fruit thinning occurred at 10 and 16 °C. Additional fruit thinning was significantly promoted by Carbaryl or NAA + Regulaid over the range of temperatures (5 to 21 °C), but thinning appeared to be most promoted at 21 °C dark temperature. Unexpectedly, ethephon caused fruit thinning at all temperatures from 5 to 21 °C, and thinning did not appear to be affected by temperature (ethephon defruited all trees at all temperatures). We suspect that higher dark temperatures caused either higher respiration rates or higher natural ethylene production, which promoted fruit abscission whether treated with a thinner or not. In one field experiment, Carbaryl sprays were applied at 2-h intervals beginning at 6 a.m. until 8 p.m. to Empire/Mark trees. Similar fruit thinning occurred when applied at temperatures ranging from 18 to 36 °C. These data suggest that no differences in thinning were related to daytime temperature.
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Chen, Chenggang, Sabyasachi Ganguli, Ajit K. Roy, and Jason Foley. "Highly Conductive Polymer Nanocomposite – Application in Interconnects and Traces." MRS Advances 1, no. 1 (2015): 9–14. http://dx.doi.org/10.1557/adv.2015.37.
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ABSTRACTCommercial off-the-shelf (COTS) electronics are generally not specifically designed to perform in extremely transient high impact scenarios. This research focused on the development of a silver-decorated carbon black-based polymeric nanocomposite with properties such as high conductivity, flexibility, and shock absorbency. Polymeric rubber materials are generally very flexible and shock absorbing, however, most polymeric materials are electrical insulators. The dispersion of the silver-decorated carbon black into the polymeric matrix could significantly improve the electrical conductivity. The processing and fabrication of Ag-CB (silver-carbon black)/Epoxy (thermosetting epoxy polymer) and Ag-CB/TPU (thermoplastic polyurethane) will be reported. Both Ag-CB/Epoxy and Ag-CB/TPU mixtures with solvents showed the shear-thinning behavior, which was an important characteristic for direct printing of traces and Additive Manufacturing (AM). The mechanical properties of the nanocomposites were measured using Dynamic Mechanical Analysis (DMA) over a wide range of temperatures. These nanocomposite materials were also successfully used to print flexible circuits using a 3D-printing machine. The electrical resistance change for the Ag-CB/Epoxy on polydimethylsiloxane (PDMS) and Ag-CB/TPU on PDMS under strain was studied, and the results will be discussed.
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Kon, Thomas M., Melanie A. Schupp, Hans E. Winzeler, and James R. Schupp. "Screening Thermal Shock as an Apple Blossom Thinning Method. I. Stigmatic Receptivity, Pollen Tube Growth, and Leaf Injury in Response to Temperature and Timing of Thermal Shock." HortScience 55, no. 5 (2020): 625–31. http://dx.doi.org/10.21273/hortsci14615-19.
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The use of short-duration applications of thermal energy (thermal shock; TS) as an apple blossom thinning strategy was investigated. Effects of TS temperature and timing on stigmatic receptivity, pollen tube growth in vivo, and visible leaf injury were evaluated in multiple experiments on ‘Crimson Gala’. TS treatments were applied to blossoms and spur leaves using a variable temperature heat gun. TS temperatures ≥86 °C had a strong inhibitory effect on pollen tube growth on the stigmatic surface and in the style. TS temperatures >79 °C reduced average pollen tube length to less than the average style length. Timing of TS treatment (0 or 24 hours after pollination) was not an influential factor, indicating that effective TS temperatures reduced pollen tube growth up to 24 hours after the pollination event. The onset of thermal injury to vegetative tissues occurred at similar TS temperatures that inhibited pollen tube growth in vivo. Excessive leaf injury (>33%) was observed at 95 °C, suggesting relatively narrow differences in thermal sensitivity between reproductive and vegetative tissues. Inconsistent TS temperatures and/or responses were observed in some experiments. Ambient air temperature may have influenced heat gun output temperatures and/or plant susceptibility. While results suggest some promise, additional work is required to validate and further develop this concept.
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Sanal Kumar, V. R., Bharath Rajaghatta Sundararam, Pradeep Kumar Radhakrishnan, et al. "In vitro prediction of the lower/upper-critical biofluid flow choking index and in vivo demonstration of flow choking in the stenosis artery of the animal with air embolism." Physics of Fluids 34, no. 10 (2022): 101302. http://dx.doi.org/10.1063/5.0105407.
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Diagnostic investigations of aneurysm, hemorrhagic stroke, and other asymptomatic cardiovascular diseases and neurological disorders due to the flow choking (biofluid/boundary layer blockage persuaded flow choking) phenomenon in the circulatory system of humans and animals on the Earth and in the human spaceflight are active research topics of topical interest {Kumar et al., “boundary layer blockage persuaded flow choking leads to hemorrhagic stroke and other neurological disorders in earth and human spaceflight,” Paper presented at the Basic Cardiovascular Sciences Conference, 23–25 August 2021 (American Stroke Association, 2021) [Circ. Res. 129, AP422 (2021)] and “Lopsided blood-thinning drug increases the risk of internal flow choking and shock wave generation causing asymptomatic stroke,” in International Stroke Conference, 19–20 March 2021 (American Stroke Association, 2021) [Stroke 52, AP804 (2021)]}. The theoretical concept of flow choking [Kumar et al., “Lopsided blood-thinning drug increases the risk of internal flow choking leading to shock wave generation causing asymptomatic cardiovascular disease,” Global Challenges 5, 2000076 (2021); “Discovery of nanoscale boundary layer blockage persuaded flow choking in cardiovascular system—Exact prediction of the 3D boundary-layer-blockage factor in nanotubes,” Sci. Rep. 11, 15429 (2021); and “The theoretical prediction of the boundary layer blockage and external flow choking at moving aircraft in ground effects,” Phys. Fluids 33(3), 036108 (2021)] in the cardiovascular system (CVS) due to gas embolism is established herein through analytical, in vitro (Kumar et al., “Nanoscale flow choking and spaceflight effects on cardiovascular risk of astronauts—A new perspective,” AIAA Paper No. 2021-0357, 2021), in silico (Kumar et al., “Boundary layer blockage, Venturi effect and cavitation causing aerodynamic choking and shock waves in human artery leading to hemorrhage and massive heart attack—A new perspective,” AIAA Paper No. 2018-3962, 2018), and in vivo animal methodology [Jayaraman et al., “Animal in vivo: The proof of flow choking and bulging of the downstream region of the stenosis artery due to air embolism,” Paper presented at the Basic Cardiovascular Sciences Conference , 25–28 July 2022 (American Heart Association, 2022)]. The boundary layer blockage persuaded flow choking phenomenon is a compressible viscous flow effect, and it arises at a critical pressure ratio in continuum/non-continuum real-world yocto to yotta scale flow systems and beyond [Kumar et al., “Universal benchmark data of the three-dimensional boundary layer blockage and average friction coefficient for in silico code verification,” Phys. Fluids 34(4), 041301 (2022)]. The closed-form analytical models, capable of predicting the flow choking in CVS, developed from the well-established compressible viscous flow theory are reviewed and presented herein. The lower-critical flow-choking index of the healthy subject (human being/animal) is predicted through the speciation analysis of blood. The upper-critical flow-choking index is predicted from the specific heat of blood at constant pressure (Cp) and constant volume (Cv), estimated using the Differential Scanning Calorimeter. These flow-choking indexes, highlighted in terms of systolic-to-diastolic blood pressure ratio (SBP/DBP), are exclusively controlled by the biofluid/blood heat capacity ratio (BHCR = Cp/Cv). An in vitro study shows that nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) gases are predominant in fresh-blood samples of the healthy humans and Guinea pigs at a temperature range of 37–40 °C (98.6–104 °F) causing gas embolism. In silico results demonstrated the existence of the biofluid/boundary layer blockage persuaded flow choking, stream tube flow choking, shock wave generation, and pressure overshoot in the downstream region of simulated arteries (with and without stenosis), at a critical pressure ratio, due to gas embolism. The flow choking followed by aneurysm (i.e., bulging of the downstream region of the stenosis artery due to shock wave generation) due to air embolism is demonstrated through small animal in vivo studies. We could corroborate herein, with the animal in vivo and three-dimensional in silico studies, that flow-choking followed by shock wave generation and pressure overshoot occurs in arteries with stenosis due to air embolism at a critical pressure ratio. Analytical models reveal that flow-choking occurs at relatively high and low blood viscosities in CVS at a critical blood pressure ratio (BPR), which leads to memory effect (stroke history/arterial stiffness) and asymptomatic cardiovascular diseases [Kumar et al., “Lopsided blood-thinning drug increases the risk of internal flow choking leading to shock wave generation causing asymptomatic cardiovascular disease,” Global Challenges 5, 2000076 (2021)]. We concluded that an overdose of drug for reducing the blood viscosity enhances the risk of flow choking (biofluid/boundary layer blockage persuaded flow choking) due to an enhanced boundary layer blockage (BLB) factor because of the rise in Reynolds number ( Re) and turbulence. An analytical model establishes that an increase in Re due to the individual or the joint effects of fluid density, fluid viscosity, fluid velocity, and the hydraulic diameter of the vessel creates high turbulence level in CVS instigating an escalated BLB factor heading to a rapid adverse flow choking. Therefore, prescribing the exact blood-thinning course of therapy is crucial for achieving the anticipated curative value and further annulling adverse flow choking (biofluid/boundary layer blockage persuaded flow choking) in CVS. We could conclude authoritatively herein, with the animal in vivo studies, that flow choking occurs in the artery with stenosis due to air embolism at a critical BPR (i.e., SBP/DBP = 1.892 9), which is regulated by the heat capacity ratio of air. The cardiovascular risk due to boundary layer blockage persuaded flow choking could be diminished by concurrently reducing the viscosity of biofluid/blood and flow-turbulence. This comprehensive review is a pointer toward achieving relentless unchoked flow conditions (i.e., flow Mach number < 1) in the CVS for prohibiting asymptomatic cardiovascular diseases and neurological disorders associated with flow choking and shock wave generation followed by pressure overshoot causing arterial stiffness. The unchoked flow condition can be achieved in every subject (human/animal) by suitably increasing the thermal-tolerance-level in terms of BHCR and/or by reducing the BPR within the pathophysiological range of individual subjects through the new drug discovery, the new companion drug with the conventional blood thinners and/or proper health care management for increasing the healthy-life span of one and all in the universe.
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Khazaei, Sahel, Mehrdad Motamed Shariati, Naser Shoeibi, Mohammad Arjmand, and Seyedeh Maryam Hosseini. "Paracentral Acute Middle Maculopathy and Central Retinal Venous Occlusion following Electrical Injury." Case Reports in Ophthalmological Medicine 2022 (April 16, 2022): 1–4. http://dx.doi.org/10.1155/2022/3699667.
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Purpose. To report a case of central retinal vein occlusion (CRVO) and paracentral acute middle maculopathy (PAMM) following electric shock injury. Case Description. A 45-year-old male presented with a significant painless decreased vision in the right eye following an electrical injury of the right hand in his workplace. The best-corrected visual acuity (BCVA) of the right eye was 20/40. Funduscopic examination of the right eye revealed diffuse superficial and deep intraretinal hemorrhages, mild venous tortuosity, and an area of the pale retina. Optical coherence tomography (OCT) demonstrated hyperreflective band-like lesions in the middle retinal layers. Patchy areas of vascular flow void in deep capillary plexus seen in OCT angiography of the right eye were compatible with PAMM. Fluorescein angiography of the right eye was indicative of delayed venous filling suggestive of CRVO. The left eye was completely normal on exam and imaging. Conclusion. This report illustrates the occurrence of CRVO associated with PAMM following electric shock injury. Electrical injury leads to a wide range of retinal manifestations. Clinicians need to pay attention to any hyperreflectivity and thinning of middle retinal layers in OCT in cases with the presentation of sudden visual loss following electrical injuries.
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Kakandikar, Ganesh, and Vilas Nandedkar. "Springback optimization in automotive Shock Absorber Cup with Genetic Algorithm." Manufacturing Review 5 (2018): 1. http://dx.doi.org/10.1051/mfreview/2017013.
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Drawing or forming is a process normally used to achieve a required component form from a metal blank by applying a punch which radially draws the blank into the die by a mechanical or hydraulic action or combining both. When the component is drawn for more depth than the diameter, it is usually seen as deep drawing, which involves complicated states of material deformation. Due to the radial drawing of the material as it enters the die, radial drawing stress occurs in the flange with existence of the tangential compressive stress. This compression generates wrinkles in the flange. Wrinkling is unwanted phenomenon and can be controlled by application of a blank-holding force. Tensile stresses cause thinning in the wall region of the cup. Three main types of the errors occur in such a process are wrinkling, fracturing and springback. This paper reports a work focused on the springback and control. Due to complexity of the process, tool try-outs and experimentation may be costly, bulky and time consuming. Numerical simulation proves to be a good option for studying the process and developing a control strategy for reducing the springback. Finite-element based simulations have been used popularly for such purposes. In this study, the springback in deep drawing of an automotive Shock Absorber Cup is simulated with finite element method. Taguchi design of experiments and analysis of variance are used to analyze the influencing process parameters on the springback. Mathematical relations are developed to relate the process parameters and the resulting springback. The optimization problem is formulated for the springback, referring to the displacement magnitude in the selected sections. Genetic Algorithm is then applied for process optimization with an objective to minimize the springback. The results indicate that a better prediction of the springback and process optimization could be achieved with a combined use of these methods and tools.
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Фролов, Евгений Андреевич, Владимир Вячеславович Драгобецкий та Станислав Георгиевич Ясько. "ВИЗНАЧЕННЯ ВПЛИВУ ТЕХНОЛОГІЧНИХ ЧИННИКІВ НА ПРОЦЕС ІНТЕНСИФІКАЦІЇ ПНЕВМОУДАРНОГО ШТАМПУВАННЯ ВИТЯГУВАННЯМ І ТОЧНІСТЬ ШТАМПОВАНИХ ДЕТАЛЕЙ". Open Information and Computer Integrated Technologies, № 86 (14 лютого 2020): 108–16. http://dx.doi.org/10.32620/oikit.2019.86.07.
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This work is devoted to experimental studies to determine the influence of technological factors on the process of intensification of pneumatic shock punching by drawing and accuracy of stamped products. The process of pneumatic shock extraction, as well as other impulse methods of extraction (explosive, electrohydraulic and magneto-pulse) is complicated by the high speed of deformation and, accordingly, by the occurrence of considerable inertial forces that counteract the movement of the flange of the extracted part. In the case of pneumatic shock reduction of the deformation rate can be achieved by adjusting the relative weight of the striker or by applying a two-stroke stretching. It is experimentally confirmed that the greatest influence on the limit values of the stamping ability in pneumatic impact stamping have the properties of the workpiece material, its surface properties, the scheme of the deformation process, the rate of deformation, the geometry of the matrix or punch, the value of contact friction and intensification techniques. Experiments have shown that the following factors have the greatest influence on the ultimate degree of drawing and the quality of the products: the condition of the surface and the physical and mechanical properties of the workpiece material; the radius of curvature of the working edge of the matrix; the relative thickness of the workpiece; workpiece loading rate (parameter α); the frictional properties of the matrix material and the workpiece; quality of greasing; technological scheme of operation. For two-stroke stretching, the stretching limit is increased by 8-10%. Also, when using two-stroke load, as shown by experiments, the amount of thinning in dangerous sections of the finished product is reduced. The reduction of radial deformation in the centre of the samples reaches 20-25%. The accuracy of pneumatic shock punching by a liquid is very high, since the deviation of the measured diameters does not exceed 0.1 mm. The surface quality of the pneumatic impacted products is determined only by the surface quality of the starting material. The pneumatic shock method of punching using a two-stage folded dash allows to increase the degree of drawing, accuracy and quality by means of a two-stroke loading, that is, to intensify the process of deep drawing of sheet products. The intensification is due to the successive double shock load for one cycle of the PUSH installation – the first blow is a formative, and the subsequent blow of the second stage is a calibration.
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Kumar, Valsalayam Raghavapanicker Sanal, Shiv Kumar Choudhary, Pradeep Kumar Radhakrishnan, et al. "Lopsided Blood‐Thinning Drug Increases the Risk of Internal Flow Choking Leading to Shock Wave Generation Causing Asymptomatic Cardiovascular Disease." Global Challenges 5, no. 3 (2021): 2000076. http://dx.doi.org/10.1002/gch2.202000076.
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Noel, Alexis C., Hao-Yuan Guo, Mark Mandica, and David L. Hu. "Frogs use a viscoelastic tongue and non-Newtonian saliva to catch prey." Journal of The Royal Society Interface 14, no. 127 (2017): 20160764. http://dx.doi.org/10.1098/rsif.2016.0764.
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Frogs can capture insects, mice and even birds using only their tongue, with a speed and versatility unmatched in the world of synthetic materials. How can the frog tongue be so sticky? In this combined experimental and theoretical study, we perform a series of high-speed films, material tests on the tongue, and rheological tests of the frog saliva. We show that the tongue's unique stickiness results from a combination of a soft, viscoelastic tongue coupled with non-Newtonian saliva. The tongue acts like a car's shock absorber during insect capture, absorbing energy and so preventing separation from the insect. The shear-thinning saliva spreads over the insect during impact, grips it firmly during tongue retraction, and slides off during swallowing. This combination of properties gives the tongue 50 times greater work of adhesion than known synthetic polymer materials such as the sticky-hand toy. These principles may inspire the design of reversible adhesives for high-speed application.
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Lai, Jianping, Xin Shen, Xiaohu Yuan, et al. "The Effect of Shot Blasting Abrasive Particles on the Microstructure of Thermal Barrier Coatings Containing Ni-Based Superalloy." Coatings 14, no. 10 (2024): 1312. http://dx.doi.org/10.3390/coatings14101312.
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Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet been fully elucidated. In this study, the superalloy substrate was grit-blasted using various processing parameters, followed by the deposition of thermal barrier coatings (TBCs) consisting of a metallic bond coat (BC) and a ceramic top coat (TC). After thermal shock tests, local thinning or discontinuities in the thermally grown oxide (TGO) layer were observed in TBCs where large grit particles were embedded at the BC/substrate interface. Moreover, cracks originated at the concave positions of the TGO layer and propagated vertically towards BC; these cracks may be associated with additional stress imposed by the foreign grit particles during thermal cycling. At the BC/substrate interface, crack origins were observed in the vicinity of large grit particles (~50 μm).
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Sun, Jingya, Sujuan Jiao, Xiuchang Huang, and Hongxing Hua. "Investigation into the Impact and Buffering Characteristics of a Non-Newtonian Fluid Damper: Experiment and Simulation." Shock and Vibration 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/170464.
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Dampers are widely applied to protect devices or human body from severe impact or harmful vibration circumstances. Considering that dampers with low velocity exponent have advantages in energy absorption, they have been widely used in antiseismic structures and shock buffering. Non-Newtonian fluid with strong shear-thinning effect is commonly adopted to achieve this goal. To obtain the damping mechanism and find convenient methods to design the nonlinear fluid damper, in this study, a hydraulic damper is filled with 500,000 cSt silicone oil to achieve a low velocity exponent. Drop hammer test is carried out to experimentally obtain its impact and buffering characteristics. Then a coupling model is built to analyze its damping mechanism, which consists of a model of impact system and a computational fluid dynamics (CFD) model. Results from the coupling model can be consistent with the experiment results. Simulation method can help design non-Newtonian fluid dampers more effectively.
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Montenegro, Miguel, and Francisco J. Galindo-Rosales. "On the Complex Flow Dynamics of Shear Thickening Fluids Entry Flows." Micromachines 15, no. 11 (2024): 1281. http://dx.doi.org/10.3390/mi15111281.
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Due to their nature, using shear thickening fluids (STFs) in engineering applications has sparked an interest in developing energy-dissipating systems, such as damping devices or shock absorbers. The Rheinforce technology allows the design of customized energy dissipative composites by embedding microfluidic channels filled with STFs in a scaffold material. One of the reasons for using microfluidic channels is that their shape can be numerically optimized to control pressure drop (also known as rectifiers); thus, by controlling the pressure drop, it is possible to control the energy dissipated by the viscous effect. Upon impact, the fluid is forced to flow through the microchannel, experiencing the typical entry flow until it reaches the fully developed flow. It is well-known for Newtonian fluid that the entrance flow is responsible for a non-negligible percentage of the total pressure drop in the fluid; therefore, an analysis of the fluid flow at the entry region for STFs is of paramount importance for an accurate design of the Rheinforce composites. This analysis has been numerically performed before for shear-thickening fluids modeled by a power-law model; however, as this constitutive model represents a continuously growing viscosity between end-viscosity plateau values, it is not representative of the characteristic viscosity curve of shear-thickening fluids, which typically exhibit a three-region shape (thinning-thickening-thinning). For the first time, the influence of these three regions on the entry flow on an axisymmetric pipe is analyzed. Two-dimensional numerical simulations have been performed for four STFs consisting of four dispersions of fumed silica nanoparticles in polypropylene glycol varying concentrations (7.5–20 wt%).
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Yan, Weiliang, Cong Li, Zhiyuan Liu, Chunyu Cheng, and Li Yang. "Reliability Evaluation of EB-PVD Thermal Barrier Coatings in High-Speed Rotation and Gas Thermal Shock." Coatings 14, no. 1 (2024): 136. http://dx.doi.org/10.3390/coatings14010136.
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The uncertain service life of thermal barrier coatings (TBCs) imposes constraints on their secure application. In addressing this uncertainty, this study employs the Monte Carlo simulation method for reliability evaluation, quantifying the risk of TBC peeling. For reliability evaluation, the failure mode needs to be studied to determine failure criteria. The failure mode of high-speed rotating TBCs under gas thermal shock was studied by combining fluid dynamics simulations and experiments. Based on the main failure mode, the corresponding failure criterion was established using the energy release rate, and its limit state equation was derived. After considering the dispersion of parameters, the reliability of TBCs was quantitatively evaluated using failure probability and sensitivity analysis methods. The results show that the main mode is the fracture of the ceramic layer itself, exhibiting a distinctive top-down “step-like” thinning and peeling morphology. The centrifugal force emerges as the main driving force for this failure mode. The failure probability value on the top side of the blade is higher, signifying that coating failure is more likely at this location, aligning with the experimental findings. The key parameters influencing the reliability of TBCs are rotation speed, temperature, and the thermal expansion coefficient. This study offers a valuable strategy for the secure and reliable application of TBCs on aeroengine turbine blades.
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Panagopoulou, Panagiota, Constantinos H. Davos, Derek J. Milner та ін. "Desmin mediates TNF-α–induced aggregate formation and intercalated disk reorganization in heart failure". Journal of Cell Biology 181, № 5 (2008): 761–75. http://dx.doi.org/10.1083/jcb.200710049.
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We explored the involvement of the muscle-specific intermediate filament protein desmin in the model of tumor necrosis factor α (TNF-α)–induced cardiomyopathy. We demonstrate that in mice overexpressing TNF-α in the heart (α–myosin heavy chain promoter-driven secretable TNF-α [MHCsTNF]), desmin is modified, loses its intercalated disk (ID) localization, and forms aggregates that colocalize with heat shock protein 25 and ubiquitin. Additionally, other ID proteins such as desmoplakin and β-catenin show similar localization changes in a desmin-dependent fashion. To address underlying mechanisms, we examined whether desmin is a substrate for caspase-6 in vivo as well as the implications of desmin cleavage in MHCsTNF mice. We generated transgenic mice with cardiac-restricted expression of a desmin mutant (D263E) and proved that it is resistant to caspase cleavage in the MHCsTNF myocardium. The aggregates are diminished in these mice, and D263E desmin, desmoplakin, and β-catenin largely retain their proper ID localization. Importantly, D263E desmin expression attenuated cardiomyocyte apoptosis, prevented left ventricular wall thinning, and improved the function of MHCsTNF hearts.
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Kuhlmann-Wilsdorf, D., B. C. Cai, and R. B. Nelson. "Plastic flow between Bridgman anvils under high pressures." Journal of Materials Research 6, no. 12 (1991): 2547–64. http://dx.doi.org/10.1557/jmr.1991.2547.
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The shear strength of materials after extensive plastic flow under a superimposed high hydrostatic stress component is most conveniently studied by means of Bridgman opposed anvils between which thin disk-shaped samples are sheared through relative rotation. A newly designed apparatus of this type permits, for the first time ever, the monitoring of sample thickness during shearing and thus the obtaining of averaged shear stress/shear strain curves. Such relations are needed for the better understanding of geological processes, behavior under shock or explosive impact, and of the surface layers during friction and wear, among others. A semiquantitative analysis shows that nonuniform pressure distribution in the samples cannot significantly falsify the results. It is concluded that distributed shearing is always accompanied by sample thinning and that, conversely, slippage between anvils and specimens is indicated whenever the sample stops thinning during rotation. Such slippage can be greatly reduced by raising the friction coefficient through etching of samples and/or anvils, but it apparently occurred undiscovered in previous studies, partly after initial distributed shearing. Further, in previous results slippage between directly contacting anvils was frequently mistaken for sample shearing. Additionally, the previously neglected sample material being extruded during shearing can falsify results, as can “turbulent flow” initiated at sample perforation. Correspondingly all prior data gained with Bridgman apparatuses are suspect. Present best results indicate (i) that in metals ordinary dislocation glide but apparently with strongly increased Peierls–Nabarro stresses continues to the highest pressures studied, (ii) that independent of thermal activation workhardening may cease at high strains, and (iii) that “turbulent flow” resulting through sample perforation or when the sample thickness decreases below a critical value, can give rise to mechanical alloying. The majority if not all of the data by Bridgman as well as Vereshchagin et al. probably involved such mechanical alloying. When plotted versus pressure in units of shear moduli, the apparent coefficients of friction of the five cubic metals examined so far follow nearly the same curve but they are lower for metals of lower symmetry.
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Mochalova, Marina N., Viktor A. Mudrov, Anastasia Yu Alexeyeva, and Lyubov A. Kuzmina. "A clinical case of the uterine complete rupture along with the previous scar during pregnancy with atypical clinical features." Journal of obstetrics and women's diseases 70, no. 5 (2021): 141–46. http://dx.doi.org/10.17816/jowd63471.
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This article presents an unusual case of rupture of the scarred uterus at 36-37 weeks of gestation. The patient presented with pain in the pubic and hip joint area, growing stronger while her walking, seated and changing position. No clinical manifestations of hemorrhagic shock were observed. External obstetric examination revealed a normotonic uterus and satisfactory fetus condition. Provocation tests were conducted to exclude subluxation of the pubic joint. Pubic symphysis diastasis palpation, long dorsal sacroiliac ligament palpation, P4 test, Patricks test, and the modified Trendelenburg test were negative. Pelvic examination revealed sharp pain in lower uterus segment. Ultrasound scan revealed deformation and thinning of the scar up to 1 mm, and no abnormalities in pubic symphysis. A threatening uterine rupture was diagnosed, and emergency cesarean section was performed. Intraoperative examination showed that the scar located in the lower segment consisted of connective tissue. In addition, there was a 4 5 cm scar defect with the overlying amniotic sac, no hemorrhage being noted. After removing the fetus, scar excision was performed. The uterine defect was repaired with a double layer running-locking suture. The patient was discharged from hospital on day 5 of postpartum period. The infant was exposed in the neonatal intensive care unit to provide an early developmental care.
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Ligorio, Cosimo, Judith A. Hoyland, and Alberto Saiani. "Self-Assembling Peptide Hydrogels as Functional Tools to Tackle Intervertebral Disc Degeneration." Gels 8, no. 4 (2022): 211. http://dx.doi.org/10.3390/gels8040211.
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Low back pain (LBP), caused by intervertebral disc (IVD) degeneration, is a major contributor to global disability. In its healthy state, the IVD is a tough and well-hydrated tissue, able to act as a shock absorber along the spine. During degeneration, the IVD is hit by a cell-driven cascade of events, which progressively lead to extracellular matrix (ECM) degradation, chronic inflammation, and pain. Current treatments are divided into palliative care (early stage degeneration) and surgical interventions (late-stage degeneration), which are invasive and poorly efficient in the long term. To overcome these limitations, alternative tissue engineering and regenerative medicine strategies, in which soft biomaterials are used as injectable carriers of cells and/or biomolecules to be delivered to the injury site and restore tissue function, are currently being explored. Self-assembling peptide hydrogels (SAPHs) represent a promising class of de novo synthetic biomaterials able to merge the strengths of both natural and synthetic hydrogels for biomedical applications. Inherent features, such as shear-thinning behaviour, high biocompatibility, ECM biomimicry, and tuneable physiochemical properties make these hydrogels appropriate and functional tools to tackle IVD degeneration. This review will describe the pathogenesis of IVD degeneration, list biomaterials requirements to attempt IVD repair, and focus on current peptide hydrogel materials exploited for this purpose.
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Pelles-Taskó, Beáta, Réka Szekeres, Barbara Takács, et al. "From Nature to Treatment: The Impact of Pterostilbene on Mitigating Retinal Ischemia–Reperfusion Damage by Reducing Oxidative Stress, Inflammation, and Apoptosis." Life 14, no. 9 (2024): 1148. http://dx.doi.org/10.3390/life14091148.
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Retinal ischemia–reperfusion (I/R) injury is a critical pathogenic mechanism in various eye diseases, and an effective therapeutic strategy remains unresolved. Natural derivatives have recently reemerged; therefore, in our present study, we examined the potential therapeutic effects of a stilbenoid that is chemically related to resveratrol. Pterostilbene, recognized for its anti-inflammatory, anti-carcinogenic, anti-diabetic, and neuroprotective properties, counteracts oxidative stress during I/R injury through various mechanisms. This study explored pterostilbene as a retinoprotective agent. Male Sprague Dawley rats underwent retinal I/R injury and one-week reperfusion and were treated with either vehicle or pterostilbene. After this functional electroretinographical (ERG) measurement, Western blot and histological analyses were performed. Pterostilbene treatment significantly improved retinal function, as evidenced by increased b-wave amplitude on ERG. Histological studies showed reduced retinal thinning and preserved the retinal structure in the pterostilbene-treated groups. Moreover, Western blot analysis revealed a decreased expression of glial fibrillary acidic protein (GFAP) and heat shock protein 70 (HSP70), indicating reduced glial activation and cellular stress. Additionally, the expression of pro-apoptotic and inflammatory markers, poly(ADP-ribose) polymerase 1 (PARP1) and nuclear factor kappa B (NFκB) was significantly reduced in the pterostilbene-treated group. These findings suggest that pterostilbene offers protective effects on the retina by diminishing oxidative stress, inflammation, and apoptosis, thus preserving retinal function and structure following I/R injury. This study underscores pterostilbene’s potential as a neuroprotective therapeutic agent for treating retinal ischemic injury and related disorders.
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Adeleke, Adelani Ismail, Mufutau Adekojo Waheed, Gbeminiyi Musibau Sobamowo, and Antonio Marcos de Oliveira Siqueira. "Viscoelastic Fluid Flow Model for Hydrodynamic Behaviour of Magnetorheological Fluid in Valve and Shear Modes for a Damper System." Journal of Engineering and Exact Sciences 10, no. 7 (2024): 19082. http://dx.doi.org/10.18540/jcecvl10iss7pp19082.
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In this present study, the flow behaviour of magnetorheological fluid in valve and shear modes for damping system is modelled and analysed. The fluid is modelled as viscoelastic fluid flowing between two parallel plates in pressure driven flow mode, and also as direct shear mode. In the work, the post-yield shear thinning or thickening behaviour of magnetorheological fluids are accounted for. The velocity and pressure distributions in the unsteady magnetorheological fluid flow between the electrodes of the damper are obtained by solving the momentum equation of the magnetorheological fluid flow using the Laplace transform method. There is an excellent agreement between the results of the present model and the results of the experimental studies. The adopted viscoelastic flow model describes that the rheological behaviour of the fluid is separated into distinct pre-yield and post-yield regimes. The fluid flow velocity, velocity gradient, and shear stresses have all been shown to be enhanced by an increase in the pressure drop. The viscosity of the fluid increases with an increase in the volume fraction of particles in the fluid, which causes the resistance of the fluid to flow to increase and thereby, reduces the fluid flow velocity. Fluid flow velocity is decreased as a result of increasing magnetic field strength. The design of clutches, rotary brakes, dampers, shock absorbers, prosthetic devices, polishing and grinding tools, etc. will all benefit greatly from the adoption of the current model.
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Lakhno, I. V., S. V. Korovai, I. M. Sykal, S. M. Korovai, A. V. Repnikova, and A. E. Tkachev. "Selection of the surgical intervention in rare cases of ectopic pregnancy: clinical cases." UKRAINIAN JOURNAL HEALTH OF WOMAN, no. 5(174) (November 20, 2024): 73–76. https://doi.org/10.15574/hw.2024.5(174).7376.
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Ectopic pregnancy is a significant problem of modern gynecology. Recently, a new variant of ectopic pregnancy with localization in the area of the surgical scar after cesarean section has appeared. The etiology of cervical pregnancy is still unknown. Both types have a high threat to a woman's life and health. There is certain treatment strategies aimed at preserving fertility. However, the urgency of the situation affects the choice of method and volume of operative treatment. The aim of the work was to substantiate the adequacy of access and the extent of surgical intervention in patients with ectopic pregnancy according to the clinical situation. Clinical cases. This article demonstrates 2 cases of ectopic pregnancy that required hysterectomy. In the first case, an emergency hysteroresectoscopy was performed on a patient with vaginal bleeding due to an ectopic pregnancy in the area of the cesarean scar. However, it was not possible to stop the bleeding via coagulation of the vessels due to significant thinning and hypervascularization of the niche area. Therefore, the intervention was expanded to laparoscopy, hysterectomy. The second patient with a cervical pregnancy confirmed via ultrasonography was attended in a severe status due to a hemorrhagic shock clinic. She has been performed a laparotomy and hysterectomy. The described clinical cases demonstrate that the bleeding and hemodynamic instability of the patient affect the choice of the volume of intervention in rare cases of ectopic pregnancy. The study was conducted in accordance with the principles of the Helsinki Declaration. Informed consent was obtained from all patients. The authors declare no conflict of interest.
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Wang, Liangliang, Chun Su, Xiaofeng Jia, Zhongning Guo, and Zhixiang Zou. "Experiment and Simulation Study of the Laser-Induced Cavitation Bubble Technique for Forming a Microgroove in Aluminum Foil." Micromachines 14, no. 11 (2023): 2106. http://dx.doi.org/10.3390/mi14112106.
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The present work introduces a laser-induced cavitation bubble technique for forming an axisymmetric structure (i.e., microgroove) and the dynamics of a cavitation bubble from initial expansion to the collapse stages that were also simulated. Furthermore, the shock wave signals and dynamic properties of the cavitation bubble were recorded using a hydrophone and a high-speed camera. The experiments on microgrooves formed by laser-induced cavitation bubble stamping were carried out, and the effects of laser energy, the initial position of the bubble, and the number of impacts on the microformability of aluminum sheets are discussed. The depth of the microgroove was investigated using experiments, and it was found that the process can serve as a rapid technique for impressing microfeatures on thin-sheet metals. The experimental results showed that as the initial position of the bubble increased, the deformation depth decreased. As the laser energy and number of impacts increased, the deformation depth increased. The results of the response surface experiments showed that a laser energy of 27 mJ, 3 impacts, and a bubble position of 3 mm were optimal for the process. By using the optimal parameters, flat and smooth microgrooves with a forming depth of 102.54 µm were successfully fabricated. Furthermore, the maximum thickness thinning of the microgroove section occurred at the entrance areas, and this area had the greatest hardness. This also indicated that the greatest amount of plastic deformation of the material and grain refinement occurred in this area. On the other hand, the aluminum foil did not undergo oxidation during the plastic deformation process. These results demonstrated that laser-induced bubble stamping is an advanced micromachining method with promising applications.
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Gattari, B., D. Betta, and N. Gasparetto. "SURGICAL REPAIR AND PERCUTANEOUS CLOSURE FOR POSTINFARCTION VENTRICULAR RUPTURE." European Heart Journal Supplements 26, Supplement_2 (2024): ii155. http://dx.doi.org/10.1093/eurheartjsupp/suae036.385.
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Abstract Case Report A 44–year–old male was admitted to ICU for inferior STEMI in cardiogenic shock. The echocardiogram documented pericardial effusion in the right ventricle with initial signs of tamponade and the left ventricle with akinesia of the inferior–posterior wall and thinning of a small lateral portion, as from a pseudoaneurysm. Pericardiocentesis was performed with subsequent restoration of haemodynamic stability. The following emergency coronary angiography showed subocclusive stenosis of a thin postero–lateral branch (culprit lesion), critical stenosis at the origin of the anterior descending artery and occlusive stenosis of a developed diagonal branch. A CT scan documented a parietal breach in the middle of the left ventricle lateral wall with a pseudoaneurysm in close contiguity with the pericardium, in a setting compatible with contained cardiac rupture [Fig.1]. Hence, the patient underwent emergency cardiac surgery: a bovine pericardium patch was placed in the infarcted area, without complications. Later, percutaneous revascularisation on the left main–left anterior descending artery was performed. A few months later the patient was asymptomatic at a cardiological check–up, nonetheless, the echocardiogram revealed aneurysmal dilatation in the middle of the left ventricle lateral wall [Fig.2]; heart CT scan and ventriculography confirmed a pseudo–aneurysmal formation at the site of previous patch placement. Cardiac surgery was unfeasible due to high intra–operative risk, therefore pseudoaneurysm percutaneous closure under radioscopic and transthoracic echocardiographic monitoring was performed, with good final echocardiographic result [Fig.3]. Discussion Cardiac rupture is a relevant high–mortality complication of acute myocardial infarction which needs to be treated promptly. Early diagnosis plays a crucial role in changing the patient‘s prognosis and is made possible by clinical, echocardiographic, haemodynamic and radiological criteria. The effectiveness of different treatment modalities is still controversial. In the presented case a surgical approach was preferred under emergency settings, while a less invasive percutaneous approach was chosen in the following and more stable situation.
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Hryzhymalskyi, Ye V. "The main complications of infusion therapy and methods to overcome them." Infusion & Chemotherapy, no. 3.2 (December 15, 2020): 57–59. http://dx.doi.org/10.32902/2663-0338-2020-3.2-57-59.
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Background. Infusion therapy (IT) is an integral part of the modern treatment process and the most common method of inpatient treatment. Indications for the IT use include dehydration, changes in blood properties, intoxication, the impossibility or inexpediency of the drug administration in other ways, the impossibility of oral nutrition, and impaired immunity.
 Objective. To describe the main complications of IT and their treatment.
 Materials and methods. Analysis of literature data on this issue.
 Results and discussion. Before conducting IT, you should take into account all the indications and contraindications and carefully read the instructions for use of drugs. It is advisable to use several drugs to reduce the number and severity of side effects. The rate of administration is important: in most cases, the safe rate is 20-30 drops per minute. Accidental needle injuries (ANI) and blood contact are potential IT risks for healthcare professionals. The National Union of Nurses of Private Practice has launched a survey of health workers to reduce the prevalence of these injuries. There are three components to injection safety: safe solution preparation, safe injection, and safe disposal. IT via the needle has a number of disadvantages: complications due to frequent punctures, limited ability to conduct long-term IT, increased risk of ANI. The installation of a permanent venous catheter reduces the likelihood of these defects. After catheter placement, before and after infusion, it should be flushed with 0.9 % NaCl, heparin or Soda-Bufer solution (“Yuria-Pharm”). However, as the number of catheterizations increases, the number of catheter-associated infections increases too, ranking third among nosocomial infections and first among the causes of bacteremia. In general, the frequency of complications of venous catheterization is 15 %. Mechanical complications occur in 5-19 % of patients, infectious – in 5-26 %, thrombotic – in 2-26 %. Complications of IT are classified into the complications due to violation of the rules of administration (hematoma, tissue damage, thrombophlebitis (septic, mechanical and chemical), embolism) or blood composition disorders (acidosis, blood thinning), as well as overdose, and specific complications (anaphylactic shock, pulmonary edema, hyperthermia). Anaphylaxis most often accompanies the introduction of nonsteroidal anti-inflammatory drugs, antibiotics, muscle relaxants, radiocontrast, hypnotics, etc. The first line of treatment of anaphylactic shock involves drug discontinuation, intravenous adrenaline, 100 % oxygen, rapid intravenous infusion of crystalloids, in case of bronchospasm – 2-3 inhalations of salbutamol. Additionally, antihistamines and glucocorticoids may be prescribed.
 Conclusions. 1. IT is an integral part of the modern treatment process and the most common method of treatment in the hospital. 2. In IT, it is advisable to use several drugs, which reduces the number and severity of side effects. 3. Potential IT risks for healthcare professionals include ANI and blood contact. 4. Injection safety requires three components: safe solution preparation, safe injection, and safe disposal. 5. Complications of IT are divided into complications due to violations of the rules of installation or violation of blood composition, as well as overdose, and specific complications. 6. Anaphylaxis often accompanies the introduction of nonsteroidal anti-inflammatory drugs, antibiotics, muscle relaxants, radiocontrast, hypnotics, etc.
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Rédei, Károly, and Henrik Meilby. "Effect of Thinning on the Diameter Increment in Black Locust (Robinia pseudoacacia L.) Stands." Acta Silvatica et Lignaria Hungarica 5, no. 1 (2009): 63–74. http://dx.doi.org/10.37045/aslh-2009-0005.
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Black locust is one of the most important stand forming tree species in Hungary, covering approximately 23% of the forested land (410 thousand ha) and providing 23% of the annual timber cut of the country. Hence, during the past two decades several experiments with this species have been carried out in the country. This paper investigates the influence of thinning on the diameter increment in an experiment including four plots. One plot was left as an unthinned control plot and three plots were thinned with various thinning intensities at age 22. The experiment was measured at ages 22, 27, 32, and 36. Apparently the thinning intensities applied on two of the plots did not come up to the intensity required to influence the diameter growth of the remaining upper-storey trees. Therefore, for a given tree size the growth of the trees on these two plots did not differ significantly from the growth of similar trees in the unthinned plot. By contrast, significant thinning effects on the diameter increment of individual trees were observed on the most heavily thinned plot. Here the diameter increment was enhanced for trees with diameters of less than 20 cm, whereas the largest trees of the stand exhibited moderately increased growth. Apparently a stand density corresponding to the heavy thinning treatment (Fw values of 22-23) is required to get a significant thinning response. On the other hand, to avoid thinning shocks, it may be recommendable to apply two moderate thinning treatments instead of a single heavy one.
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Urazbakhtin, V. F., A. V. Shchenyatsky, and F. A. Urazbakhtin. "Evolutionary Development of Pulse Technologiesin the Production of Rocket Large Parts." Vestnik IzhGTU imeni M.T. Kalashnikova 26, no. 2 (2023): 34–50. http://dx.doi.org/10.22213/2413-1172-2023-2-34-50.
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An analytical review of research since the 50s of the XXth century is presented, related to the development of stamping by explosion - a promising method of forming large hard-to-process parts, with the following results is established. The source of the force during explosion stamping is the high explosive charge. It is an important factor of criticalities during plastic deformation of a titanium alloy workpiece. There can be many reasons of their origin, and they are taken into account by researchers, but separately. At the same time, the process of force generation is quite complex, especially in the aquatic medium of the basin. However, the process of explosion stamping must be controlled under any conditions. Force delivery to the workpiece surface takes place during explosion stamping within water transfer medium in the basin. Compared with the air medium, the power of this effect increases significantly due to more complete use of the water energy capabilities. Most researchers agreed that the force effect, consisting of a shock wave, motion of a hydraulic flow and a gas bubble, result in complexity of mathematical modeling of the process of its displacement. Mechanical and geometric characteristics of the workpiece affect quality of the part made by explosion stamping. It is determined by the material ability to be plastically deformed and has the effect in strength, accuracy of geometric and angular dimensions, as well as surface condition of the part, the absence of defects, fractures and corrugations. At the same time, a unified quality assessment of the workpiece and part has not been established yet. The multiparametric process of plastic deformation during explosion stamping in water deforms not only of the workpiece, but also of the matrix, thus altering the part shape, walls thinning, the appearance of corrugations and flanges due to the complex stress state in various sections of the part. It is noted that the properties revealed during the explosion stamping, leading to change in corresponding parameters and characteristics, collectively determine the system to which systematic approach may be applied. A feature of explosion stamping study is the need for an experiment, the success of which is largely determined by the experience of the researcher. This stage of the explosion stamping evolutionary development is associated with the introduction of computer technologies into the practice of technological processes design. Research is mainly related to the use of object-oriented methods, the development and application of mathematical models that allow automating procedures for determining the parameters of the stamping process mode, followed by modeling individual actions during stamping by explosion. At the same time, it is necessary to evaluate the performance of stamping by explosion both as a whole and individual stages of its implementation.
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Paramita, Betari Dhira, Sutrisno Sutrisno, and Akhmad Yogi Pramatirta. "The Role of Methotrexate Chemotherapy in Impeding Rupture - Low-Risk Gestational Trophoblastic Neoplasia Management: A Case Report." Indonesian Journal of Obstetrics & Gynecology Science 7, no. 2 (2024): 260. http://dx.doi.org/10.24198/obgynia.v7i2.677.
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Background: Gestational Trophoblastic Neoplasia (GTN) is a type of malignant growth that originates from abnormal proliferation of placental trophoblast. GTN can even be cured in its metastatic forms with a high success rate of 90-100%. However, estimating the incidence of Gestational Trophoblastic Disease (GTD) in Indonesia is challenging due to underreporting and lack of recognition. GTD can be classified into two types: hydatidiform mole and GTN. Low-risk GTN is currently treated with methotrexate.Case presentation: A 24-year-old woman experienced vaginal bleeding for three weeks after her molar evacuation. Upon admission to Prof. Dr. Margono Seokarjo (RSMS) General Hospital, the patient was in grade III hypovolemic shock. Post-molar evacuation β-hCG examination showed increasing periodic, while ultrasound examination revealed thinning of the myometrium with vesicular pattern invaded at the fundus. Transvaginal examination results showed bilateral lutein cysts. The patient was diagnosed with low-risk GTN (FIGO score 6) with impending uterine rupture and bilateral non-papillary multilocular ovarian cysts.Discussion: GTN during pregnancy requires accurate diagnosis and prompt treatment. GTN patients who reach an undetectable β-hCG level are at risk of perforation, infection, and higher uterine bleeding. MTX chemotherapy has been proven effective as the main therapy for low-risk GTN, and the β-hCG level can be relied upon as an indicator of treatment response. The MTX chemotherapy provides a favorable prognosis for reducing β-hCG levels to prevent uterine rupture.Conclusions: The administration of MTX chemotherapy successfully prevents rupture by reducing the β-hCG levels, followed by three cycles of consolidation therapy to prevent recurrence.Peran Kemoterapi Metotrexat pada Tatalaksana Tumor Trofoblastik Gestational Risiko Rendah dengan Ancaman Ruptur Uteri: Laporan KasusAbstrak Latar belakang: Neoplasia Trofoblas Gestasional (GTN) merujuk pada lesi ganas yang timbul dari proliferasi trofoblas plasenta yang abnormal. Meskipun dalam bentuk metastasis, GTN dapat disembuhkan dengan tingkat kesembuhan mencapai 90 – 100%. Di Indonesia, estimasi insiden GTD (Penyakit Trofoblas Gestasional) menjadi tantangan terutama karena tidak semua kasus dilaporkan atau dikenali. GTD terbagi menjadi mola hidatidosa dan neoplasia trofoblas gestasional (GTN). Saat ini, metotreksat direkomendasikan untuk GTN dengan risiko rendahPresentasi Kasus: Seorang wanita berusia 24 tahun mengalami perdarahan vagina selama 3 minggu setelah evakuasi molanya. Saat masuk ke Rumah Sakit Umum Prof. Dr. Margono Soekarjo (RSMS), pasien dalam keadaan syok hipovolemik stadium III. Pemeriksaan β-hCG pascaevakuasi mola menunjukkan peningkatan periodik dan pemeriksaan ultrasonografi menunjukkan penipisan miometrium dengan pola vesikular yang menginvasi fundus. Hasil pemeriksaan transvaginal menunjukkan adanya kista lutein bilateral. Pasien didiagnosis dengan GTN risiko rendah (skor FIGO 6) dengan ancaman ruptur uterus dan kista ovarium multilokular bilateral non-papiler.Pembahasan: GTN selama kehamilan membutuhkan diagnosis yang akurat dan pengobatan yang cepat. Kemoterapi metotreksat merupakan terapi utama untuk GTN dengan risiko rendah, dan tingkat β-hCG dapat digunakan sebagai indikator respons terhadap pengobatan. Pasien GTN yang mencapai tingkat β-hCG yang tidak terdeteksi berisiko mengalami perforasi, infeksi, dan perdarahan rahim yang lebih tinggi. Penggunaan metotreksat (MTX) sebagai pengobatan utama untuk GTN dengan risiko rendah telah terbukti efektif dan memberikan prognosis yang menguntungkan. Kesimpulan: Pemberian kemoterpi MTX berhasil mencegah terjadinya ruptur karena kadar β-hCG menurun dan dilanjutkan terapi konsolidasi 3 siklus untuk mencegah terjadinya rekurensi.Kata kunci: Gestational Trophoblastic Neoplasia (GTN), Plasenta Trofoblas, Methotrexate Ruptur Uteri.
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Krotova, Yulia I., Vladimir A. Balash, and Alexey R. Faizliev. "Regional inflation spillovers in the Russian Federation." Izvestiya of Saratov University. Economics. Management. Law 25, no. 1 (2025): 27–37. https://doi.org/10.18500/1994-2540-2025-25-1-27-37.
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Introduction. A large number of studies have been devoted to the study of spillover effects in many sectors of the economy. However, inflation spillovers in regional data from Russia are studied for the first time. Theoretical analysis. This paper aims at studying inflation spillovers in the aggregate and 12 subgroups of the CPI in 26 regions of the Russian Federation. To achieve this goal, we use the Diebold and Yilmaz methodology to quantitatively assess the spillover effect for the consumer price index. Diebold and Yilmaz proposed to calculate a number of indices based on the decomposition of the variance vector autoregressive model to characterize the connectivity of the system at various levels, from pairwise to system-wide. The decomposition of the variance shows what part of the future uncertainty of region i is associated with shocks in region j. The article implements three vector autoregressive models (VAR) with thinning of coefficients (with a penalty) – the Elastic Net, Lasso and Ridge VAR models. Empirical analysis. The dynamic relationship of random shocks (spillover effects) of inflation between regions of the Russian Federation and the stability of the selected methods are studied. To calculate the spillover measures, a technique based on the decomposition of the forecast variance of multivariate time series is used. Clustering methods are used to identify spatial macroregions of the spread of inflation spillovers. Results. The transmission of random shocks on a regional basis during the period from January 2002 to June 2024 occurs from the central regions to the Siberian regions and to the Far Eastern regions. The results of the study provide new information on the heterogeneity of inflation spillovers between Russian regions.
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Ugai, M. "Computer modelling of three-dimensional dynamics of fast reconnection." Journal of Plasma Physics 45, no. 2 (1991): 251–66. http://dx.doi.org/10.1017/s0022377800015683.
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Computer simulations are used to investigate the basic three-dimensional structure of the fast reconnection mechanism spontaneously developing from a long current sheet. It is shown that if three-dimensional effects (∂sol;∂z ≠ 0) are not so strong, a locally enhanced resistivity results in current-sheet thinning, and a fast reconnection process, involving switch-off shocks, is eventually set up in a region limited in the z direction. The fast reconnection process near the z = 0 plane becomes quasi-steady and two-dimensional (∂/∂z = 0), so that the well-known Petschek mechanism is fully applicable. Distinct plasma rarefaction occurs inside the fast reconnection region, so that fast-mode expansion may propagate in the z direction, and the resulting inflow velocity uz takes the magnetic field into the fast reconnection region and contracts the latter. The global current system undergoes drastic changes during the fast-reconnection development. The current flow, initially directed in the z direction, first converges towards the neutral line, and is then largely deflected away from this line in the inner reconnection region.
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Ziaeepour, Houri. "Properties of jet and surrounding material of GW/GRB 170817A." Monthly Notices of the Royal Astronomical Society 490, no. 2 (2019): 2822–37. http://dx.doi.org/10.1093/mnras/stz2735.
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ABSTRACT We use published data in radio, optical, and X-ray bands to analyse and model afterglows of GW/GRB 170817A. Our analysis is based on a phenomenological gamma-ray burst generator model, which we previously used to study the prompt gamma-ray emission of this important transient. We find a multicomponent model and a few of its variants that are consistent with broad-band ∼1 yr observations of afterglows, once the contribution of kilonova in optical/IR band is taken into account. Considering beaming and off-axis view of relativistic outflows, we interpret the components of the model as approximately presenting the profile of a relativistic structured jet with a rapidly declining Lorentz factor from our line of sight, where it had a Lorentz factor of $\mathcal {O}(100)$, to outer boundaries, where it became a mildly relativistic cocoon with a relative velocity to light of ∼0.4–0.97. Properties of the ultra-relativistic core of the jet obtained here are consistent with conclusions from analysis of the prompt gamma-ray emission. In particular, our results show that after prompt internal shocks the remnant of the jet retained in some extent its internal collimation and coherence. Slow rise of the afterglows can be associated to low density of circumburst material and low column density of the jet. The long distance of external shocks from the merger, which could have been in part responsible for extensive thinning of the jet through expansion and energy dissipation before occurrence of external shocks, is responsible for the peak of emission being at ≳110 d after the merger. We discuss implications of these observations for origin and properties of circumburst material around binary neutron stars. This analysis confirms our previous results showing that an outflow with a Lorentz factor of ∼2–5 cannot explain observed afterglows without an additional X-ray source or significant absorption of optical/IR photons.
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Gobo, Katarina, Ervin Mrinjek, and Vlasta Ćosović. "Mass-transport deposits and the onset of wedge-top basin development: An example from the Dinaric Foreland Basin, Croatia." Journal of Sedimentary Research 90, no. 11 (2020): 1527–48. http://dx.doi.org/10.2110/jsr.2019.192.
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ABSTRACT Mass-transport deposits (MTDs) represent resedimentation phenomena triggered by the combined effect of seismic shocks of regional scale, structural tilting, basin-floor gradient, relative sea-level fluctuations, and/or excess pore-water pressure and can be useful in the reconstruction of basin development dynamics. The present study from the Dinaric Foreland Basin in Croatia documents several limestone blocks (olistoliths), carbonate debris, and associated bipartite carbonate megabeds as MTDs of exotic origin encased in deep neritic hyperpycnites, referred to as host deposits. Detailed facies and micropaleontological analyses indicate that host deposits were sourced from a fluvio-deltaic system located in the proximity of the uplifting orogen, while the MTDs originated from gravitational collapses of late Ypresian and early Lutetian limestones that were uplifted on blind-thrust anticline ridges on the opposite side of the basin. Mass wasting-produced carbonate blocks, debris, and gravity flows were probably triggered concurrently during the middle to late Eocene, but the blocks could have travelled faster downslope due to the lubricating effect of the underlying water “cushion,” overpressured mud, and the pull of gravity. Debrisflows and co-genetic turbidity currents that contributed to the formation of bipartite megabeds were likely mobilized deeper and moved slower than the carbonate blocks and could have been partly deflected by the previously emplaced olistoliths, resulting in megabed thinning along the olistoliths' down-dip edges. Those collapses were most likely triggered by the combined effect of relative sea-level changes associated with tectonic activity and seismic shocks of regional scale. The study suggests that progressive uplift of the frontal blind-thrust anticline ridge resulted in episodic emergence and collapses of progressively older limestone units, and marked the onset of development of the wedge-top basin. Conceptual models of olistolith emplacement and onset of basin development are suggested and may be applicable to both ancient and recent settings. The insights obtained from the integration of detailed facies analysis and micropaleontology may be useful in similar areas where such a level of detail cannot be obtained by conventional field methods.
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French, Kelly, Matthew Vadeboncoeur, Heidi Asbjornsen, et al. "Temporary thinning shock in previously shaded red spruce." Canadian Journal of Forest Research, February 28, 2023. http://dx.doi.org/10.1139/cjfr-2022-0227.
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Silvicultural thinning can lead to rapid microclimatic changes for residual trees. Despite the benefits of decreased competition, thinning may induce “thinning shock” – temporary negative physiological responses as trees acclimate to new conditions. We examined the impact of thinning on the microclimate and physiology of residual, previously shaded red spruce (Picea rubens Sarg.) trees relative to non-thinned controls. Both daily maximum temperature and vapor pressure deficit increased post thinning, with larger increases observed on hotter and drier days. In response to these environmental changes, we found clear evidence of physiological declines. At 1.7 weeks post thinning, we found a 0.59-MPa reduction in average midday water potential relative to control trees, which lasted for an additional 1.4 weeks. Thus, the trees in the thinning treatment were at or beyond published estimates of needle turgor loss. Thinning decreased photosynthetic efficiency of current-year needles 3.8% after two weeks, and it declined by 1.3% per week for the remainder of the growing season. These results suggest that thinning shock occurs in red spruce, a shade-adapted, climate-sensitive species. Thinning shock may contribute to the lagged growth responses commonly observed post thinning, and these effects may be more extreme in novel future climates.
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Picchio, Rodolfo, Rachele Venanzi, Francesco Latterini, Enrico Marchi, Andrea Laschi, and Monaco Angela Lo. "Corsican Pine (Pinus laricio Poiret) Stand Management: Medium and Long Lasting Effects of Thinning on Biomass Growth." May 10, 2018. https://doi.org/10.3390/f9050257.
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Originally published in Forests: Picchio R, Venanzi R, Latterini F, Marchi E, Laschi A, Lo Monaco A (2018). Corsican pine (<em>Pinus laricio</em> Poiret) stand management: medium and long lasting effects of thinning on biomass growth. <em>Forests</em> 9 (5), article number 257, p. 1-17 <strong>(open access)</strong> <strong>DOI: </strong>10.3390/f9050257<strong> </strong> This article can be downloaded at: https://www.mdpi.com/1999-4907/9/5/257 Abstract With the aim of acquiring better comprehension of the ecological and productive aspects of the management of pine forests, we monitored logging damage and evaluated the effects of thinning on stand growth 20 years after the treatment in a Pinus laricio Poiret stand in central Italy. The objectives of the present study were to estimate the injury levels to the remaining trees after thinning; to assess logging damage in the long-term by monitoring residual trees at the end of thinning; to evaluate the effect of damage on the radial growth of trees; to assess the stand dynamics in relation to injury levels and the treatment applied in a twenty-year range; to understand a possible treatment return time; and to evaluate the existence of the “thinning shock”. The results were that 20 years after treatment, the stand dynamics showed a complete recovery; logging damage did not affect the radial growth of P. laricio over time; a second treatment seem to be sustainable starting from the fifteenth year after the previous treatment; and the thinning shock can be clearly evaluated in the first six to seven years after the treatment. Keywords: stand growing; thinning shock; forest logging; tree wounds; tree ring width.
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Rana, U., T. Abadie, D. Chapman, N. Joiner, and O. K. Matar. "Richtmyer–Meshkov instability at high Mach number: Non-Newtonian effects." Physics of Fluids 36, no. 6 (2024). http://dx.doi.org/10.1063/5.0209843.
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The Richtmyer–Meshkov instability (RMI) occurs when a shock wave passes through an interface between fluids of different densities, a phenomenon prevalent in a variety of scenarios including supersonic combustion, supernovae, and inertial confinement fusion. In the most advanced current numerical modeling of RMI, a multitude of secondary physical phenomena are typically neglected that may crucially change in silico predictions. In this study, we investigate the effects of shear-thinning behavior of a fluid on the RMI at negative Atwood numbers via numerical simulations. A parametric study is carried out over a wide range of Atwood and Mach numbers that probes the flow dynamics following the impact on the interface of the initial shock wave and subsequent, reflected shocks. We demonstrate agreement between our numerical results and analytical predictions, which are valid during the early stages of the flow, and examine the effect of the system parameters on the vorticity distribution near the interface. We also carry out an analysis of the rate of vorticity production and dissipation budget which pinpoints the physical mechanisms leading to instability due to the initial and reflected shocks. Our findings indicate that the shear-thinning effects have a significant impact on instability growth and the development of secondary instabilities, which manifest themselves through the formation of Kelvin–Helmholtz waves. Specifically, we demonstrate that these effects influence vorticity generation and damping, which, in turn, affect the RMI growth. These insights have important implications for a range of applications, including inertial confinement fusion and bubble collapse within non-Newtonian materials.
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Ruban, Alex, Viren Menezes, Sridhar Balasubramanian, and K. Srinivasan. "Shock–Boundary Layer-Interaction Control Through Recirculation in a Hypersonic Inlet." Journal of Fluids Engineering 142, no. 11 (2020). http://dx.doi.org/10.1115/1.4048141.
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Abstract This technical brief presents a flow separation mitigation device, called cavity-recirculator that can be used to control flow separation during shock wave–boundary layer interaction (SBLI) in high-speed intake flows. The cavity-recirculator isolates the flow separation bubble generated at the SBLI spot, thereby thinning the boundary layer and reducing the blockage of the inviscid stream in the duct. The device has a potential application in scramjet engine intakes/isolators. The cavity-recirculator was tested on a single-ramp-compression intake model in a hypersonic shock tunnel, in a freestream of Mach 8 (±0.1). The device operation and effectiveness were assessed by flow visualization and pressure measurements in the test model. The measurements and visualization displayed a mitigation of flow separation through an improved flow field with a single shock train and the absence of flow separation shock, in the inlet.