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1
Zhang, Jian Min, Pan Wang, Gao Peng Zhang, Ya Wei Li, and Ting Cao. "Study on Supercapacity Properties of Manganese Dioxide Active Material by the Cation Concentration Change on the Electrode Surface." Advanced Materials Research 734-737 (August 2013): 2411–14. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.2411.
Анотація:
A four-electrode system was developed to measure in-situ the cation concentration change on the supercapacitor electrode surface for the first time during the charge/discharge process. While the MnO2 electrode was used in a supercapacitor in K2SO4 solution, the potassium ion concentration on the electrode surface was reversible change during the charging/discharging process, decreasing with the reduction process and increasing with the oxidation process. It is clearly clarified that the charge storage mechanism of manganese dioxide, as a supercapacitor active material, involves a fast redox reaction through reversible insertion/desertion of potassium ion and variation of manganese valance.
2
Ravikumar, V., R. P. Rodrigues, and V. P. Dravid. "Direct imaging of spatially varying potential and charge across internal interfaces in solids." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 316–17. http://dx.doi.org/10.1017/s0424820100137951.
Анотація:
The importance of spatially varying potential (and thus charge) across lattice discontinuities in solids has been recognized in many technologically important systems, especially those containing electrically active interfaces, e.g. electroceramics. The presence of spatially varying potential across electroceramic interfaces has been indirectly deduced and analyzed using predominantly bulk measurement techniques like I-V, C-V curves and impedance spectroscopy. Direct imaging of spatially varying electrostatic potential profile and determination of the sign, magnitude and spatial distribution of the associated interface- and space- charge (and therefore defect density) in electroceramics have remained elusive.We have utilized the technique of transmission high energy electron holography to directly image and quantify the electrostatic potential across grain boundaries (GBs) in SrTiO3, a functional electroceramic. The phase of the exit wave function at the GB region can be altered by : (i) variation in local mean inner potential (related to the change in density of atoms at the GB), (ii) differential diffraction conditions across the interface, (iii) change in the local specimen thickness and, (iv) presence of local electrostatic (electrical charge) and magnetic potential.
3
García-Montoya, Isui Abril, Norma Rosario Flores-Holguín, Linda-Lucila Landeros-Martínez, Mónica Alvarado-González, Quintín Rascón-Cruz, María Elena Fuentes-Montero, Pedro Palomares-Báez, and Luz María Rodríguez-Valdez. "Analysis of the Molecular Interactions between Cytochromes P450 3A4 and 1A2 and Aflatoxins: A Docking Study." Applied Sciences 9, no. 12 (June 17, 2019): 2467. http://dx.doi.org/10.3390/app9122467.
Анотація:
Mycotoxins known as aflatoxins (AF) are produced as a secondary metabolite by some species of Aspergillus fungi. They are considered carcinogenic, hepatotoxic, teratogenic, and mutagenic. In this study, the molecular structure, chemical reactivity, and charge transfer values of AFB1, B2, G1, and G2 were analyzed using density functional theory. Different methodologies—B3LYP/6-311G(d,p) and M06-2X/6-311G(d,p)—were applied for geometrical calculations. Chemical reactivity parameters were used in the calculation of charge transfer values during the interaction between protein and ligand. The binding energy, the electrostatic interactions, and the amino acids of the active site were determined by molecular docking analysis between AF and cytochromes P450 (3A4 and 1A2), employing different PDB files (CYP3A4:1TQN, 2V0M, 4NY4 and 1W0E, and CYP1A2:2HI4). Molecular docking analysis indicated that the central rings of the AF are involved in the interaction with the HEM group of the active site. The differences in the molecular structure of the AF affect their position regarding the HEM group. The resulting configurations presented considerable variation in the amino acids and the position of the coupling. The charge transfer values showed that there is oxidative damage inside the active site and that the HEM group is responsible for the main charge transferences.
4
Johnson, Kevin D., and Vinayak P. Dravid. "Dynamics Of Grain Boundary Space-Charge Potential In Electroceramics." Microscopy and Microanalysis 5, S2 (August 1999): 100–101. http://dx.doi.org/10.1017/s1431927600013829.
Анотація:
A large number of bulk and thin-film electroceramic systems contain electrically active interfaces which dictate the various useful electronic properties of these devices. The electrical activity of these interfaces stems from a complex interplay among various interfacial attribute but often involves formation of some form of electrostatic potential at the interfaces which is modified under applied bias of current and/or voltage.Figure la schematically shows charge distribution at a model grain boundary (GB), while Figure 1(b) shows its corresponding potential distribution. As shown in Figure 1(c), the energy band structure bends opposite to this built-in potential, causing a downward shift at the grain boundary . The difficulty with evaluating the Schottky barrier model, which is often invoked to explain GB electrical activity, is that the charge density distribution and therefore the band bending is expected to dynamically alter as bias is applied across the grain boundary. This variation adds another level of complexity to theoretical descriptions of the barrier behavior
5
Tian, Jing, Zhengke Pan, Shenglian Guo, Jiabo Yin, Yanlai Zhou, and Jun Wang. "Response of active catchment water storage capacity to a prolonged meteorological drought and asymptotic climate variation." Hydrology and Earth System Sciences 26, no. 19 (October 6, 2022): 4853–74. http://dx.doi.org/10.5194/hess-26-4853-2022.
Анотація:
Abstract. Studies on the hydrological response to continuous extreme and asymptotic climate change can improve our ability to cope with intensified water-related problems. Most of the literature focused on the runoff response to climate change, while neglecting the impacts of the potential variation in the active catchment water storage capacity (ACWSC) that plays an essential role in the transfer of climate inputs to the catchment runoff. This study aims to systematically identify the response of the ACWSC to a long-term meteorological drought and asymptotic climate change. First, the time-varying parameter is derived to reflect the ACWSC periodic and abrupt variations in both drought and non-drought periods. Second, the change points and varying patterns of the ACWSC are analyzed based on the Bayesian change point analysis with multiple evaluation criteria. Finally, various catchment properties and climate characteristics are used to explore the possible relationship between these variables and the temporal variation characteristics of the ACWSC. The catchments that suffered from a prolonged meteorological drought in southeast Australia were selected as the case study. Results indicate that: (1) the increase in amplitude change in the ACWSC is observed in 83/92 catchments during the prolonged drought period, and significant shifts in the mean value of the ACWSC are detected in 77/92 catchments; (2) the average response time of the ACWSC for all 92 catchments with significant changes is 641.3 d; (3) the values of the ACWSC changed significantly in the catchments with small areas, low elevations, small slope ranges, large forest coverage, and high soil water-holding capacities. This study could enhance our understanding of the variations in catchment property under climate change.
6
Gálvez, M. C., D. Montes, M. J. Fernández-Figueroa, E. De Castro, and M. Cornide. "Orbital Period Variation in the Chromospherically Active Binary FF UMa (2RE J0933+624)." Proceedings of the International Astronomical Union 2, S240 (August 2006): 706–13. http://dx.doi.org/10.1017/s1743921307006102.
Анотація:
AbstractWe present here a detailed study of FF UMa (2RE J0933+624), a recently discovered, X-ray/EUV selected, active binary system with strong Hα emission. By using high-resolution echelle spectroscopic observations taken during five observing runs from 1998 to 2004, we derived precise radial velocities that allowed us to determine the orbital solution of the system at different epochs. Analyzing these orbital solutions, together with a previous one determined in 1993 by other authors, we have found a change in the heliocentric Julian date on conjunction (Tconj) that can be explained by a change with time in the orbital period of the system. The relative amplitude of the orbital period variation derived from these data was dP/P ≈ 5 x 10−4, which is larger than the variations found in other similar chromospherically active binaries like AR Lac and HR 1099. This orbital period variation can be related (Applegate 1992; Lanza 1998, 2006) with the modulation of the gravitational quadrupole-moment of its magnetically active secondary star produced by angular momentum exchanges within its convective envelope. In addition, using these observations, we have determined the stellar parameters of the components and we have carried out a study of the chromospheric activity using all the optical indicators from Ca ii H&K to Ca ii IRT lines.
7
Cordaro, Enrique G., Patricio Venegas, and David Laroze. "Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin." Annales Geophysicae 36, no. 1 (March 1, 2018): 275–85. http://dx.doi.org/10.5194/angeo-36-275-2018.
Анотація:
Abstract. We present a different view of secular variation of the Earth's magnetic field, through the variations in the threshold rigidity known as the variation rate of geomagnetic cutoff rigidity (VRc). As the geomagnetic cutoff rigidity (Rc) lets us differentiate between charged particle trajectories arriving at the Earth and the Earth's magnetic field, we used the VRc to look for internal variations in the latter, close to the 70° south meridian. Due to the fact that the empirical data of total magnetic field BF and vertical magnetic field Bz obtained at Putre (OP) and Los Cerrillos (OLC) stations are consistent with the displacement of the South Atlantic magnetic anomaly (SAMA), we detected that the VRc does not fully correlate to SAMA in central Chile. Besides, the lower section of VRc seems to correlate perfectly with important geological features, like the flat slab in the active Chilean convergent margin. Based on this, we next focused our attention on the empirical variations of the vertical component of the magnetic field Bz, recorded in OP prior to the Maule earthquake in 2010, which occurred in the middle of the Chilean flat slab. We found a jump in Bz values and main frequencies from 3.510 to 5.860 µHz, in the second derivative of Bz, which corresponds to similar magnetic behavior found by other research groups, but at lower frequency ranges. Then, we extended this analysis to other relevant subduction seismic events, like Sumatra in 2004 and Tohoku in 2011, using data from the Guam station. Similar records and the main frequencies before each event were found. Thus, these results seem to show that magnetic anomalies recorded on different timescales, as VRc (decades) and Bz (days), may correlate with some geological events, as the lithosphere–atmosphere–ionosphere coupling (LAIC).
8
Said, Sayed M., and Bálint Hartmann. "Alleviation of Extremely Power and Voltage Variations Caused by Wind Power and Load Demand Using SMES." Periodica Polytechnica Electrical Engineering and Computer Science 63, no. 3 (March 18, 2019): 134–43. http://dx.doi.org/10.3311/ppee.13718.
Анотація:
Due to the high variations in wind speed and the continuing changes in load power demand (LPD), power and voltage at the point of common coupling (PCC) fluctuate according to the variations of injected wind power generation (WPG) and LPD simultaneously. Superconducting magnetic energy storage (SMES) plays a significant role in alleviating the power/voltage at PCC. This paper shows the impact of SMES in enhancing the performance of interconnected WPG system during high wind gust variations and the changes in LPD. WPG includes squirrel-cage induction generator (SCIG) type with a shunt-connected capacitor for improving the power factor. WPG, SMES and the load are located at PCC. Fuzzy logic control (FLC) is used with the DC-DC chopper to control the power exchange between AC system and SMES. FLC is designed where SMES can absorb/inject real power from/to the grid. On the other hand, reactive power is controlled to adjust the variation of PCC voltage. Two inputs are applied to the FLC; the summation of wind power variation and change of LPD as the first input and the variation of SMES current is the second one to control active power transferred between SMES and AC system. The suggested control approach of SMES is a fast response, as it successfully controlled the PCC voltage, line active and reactive powers during wind gusts and the variations of the load side.
9
Munshi, Parthapratim, and Kunal Jha. "Exploring Charge Transfer Mechanism in Organic NLO (Polymorphic) Materials." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C378. http://dx.doi.org/10.1107/s2053273314096211.
Анотація:
The understanding of nonlinear polarization mechanism and their relation to the structural characteristics of non-linear optical (NLO) materials have been utmost importance considering a surge in the information technology and industrial applications. Some investigations in search of NLO materials have been carried out on organic molecule scaffolds such as stilbene and chalcone having π-e-donor acceptor substituent which facilitates intermolecular charge transfer; leading to the generation of good frequency conversion materials. Few of such materials are known to exhibit polymorphic characters and most of which crystallize in non-centrosymmetric space group – necessity for a NLO material. It has been realized that the chirality, polymorphic character and NLO activity of the chalcone derivatives are mainly governed by both the substitutions at the para position and the position of sulfur atom in the thiophene ring of thienylchalcone. This presentation will highlight the preliminary results towards the analyses of electron density distributions on NLO active stilbene and chalcone derivatives and their polymorphic forms. Therefore, explore the charge transfer mechanism responsible for the variation of NLO activity across these systems and on their non-centrosymmetric polymorphic forms. Charge densities modelled using both multipole formalism (Hansen & Coppens, 1978) and X-ray constraint wavefunction fittings (Jayatilaka & Grimwood, 2001) will be considered for these studies.
10
Marin, F., and D. Hutsemékers. "Tracking the state transitions in changing-look active galactic nuclei through their polarized-light echoes." Astronomy & Astrophysics 636 (April 2020): A23. http://dx.doi.org/10.1051/0004-6361/201936123.
Анотація:
Context. Variations in the mass accretion rate appear to be responsible for the rapid transitions in spectral type that are observed in increasingly more active galactic nuclei (AGNs). These objects are now labeled “changing-look” AGNs and are key objects for understanding the physics of accretion onto supermassive black holes. Aims. We aim to complement the analysis and interpretation of changing-look AGNs by modeling the polarization variations that can be observed, in particular, polarized-light echoes. Methods. We built a complex and representative model of an AGN and its host galaxy and ran radiative transfer simulations to obtain realistic time-dependent polarization signatures of changing-look objects. Based on actual data, we allowed the system to become several times fainter or brighter within a few years, assuming a rapid change in accretion rate. Results. We obtain time-dependent polarization signatures of distant high-luminosity (quasars) and nearby low-luminosity (Seyferts) changing-look AGNs for a representative set of inclinations. We predict the evolution of the continuum polarization for future polarimetric campaigns with the goal to better understand the physics at work in these objects. We also investigate highly inclined AGNs that experience strong accretion rate variations without appearing to change state. We apply our modeling to Mrk 1018, the best-documented case of a changing-look AGN, and predict a variation in its polarization after the recent dimming of its continuum. Conclusions. We demonstrate that polarization monitoring campaigns that cover the transitions that are observed in changing-look AGNs might bring crucial information on the geometry and composition of all the reprocessing regions within the nucleus. In particular, specific features in the time variation of the polarization position angle can provide a new and efficient method for determining AGN inclinations.
11
Bansal, Kanika, and Shouvik Datta. "Dielectric Response of Light Emitting Semiconductor Junction Diodes: Frequency and Temperature Domain Study." MRS Proceedings 1635 (2014): 49–54. http://dx.doi.org/10.1557/opl.2014.206.
Анотація:
ABSTRACTWe report a change in the dielectric response of AlGaInP based multi quantum well diodes with the onset of modulated light emission. Observed variation in junction capacitance and modulated light emission, with frequency and temperature, suggests participation of slow defect channels in fast radiative recombination dynamics. Our work establishes prominent connection between electrical and optical properties of light emitting diodes and provides a tool to investigate the interesting condensed matter physics of these structures. Our observations demand a generalized physical framework, beyond conventional models, to understand an active light emitting diode under charge carrier injection. We suggest that the low frequency response can compromise the performance of these diodes under high frequency applications. We also suggest how internal quantum well structure can affect modulated light output efficiency of the device.
12
Moganti, Ganesh Lakshmana Kumar, V. N. Siva Praneeth, and Siva Rama Krishna Vanjari. "A Hybrid Bipolar Active Charge Balancing Technique with Adaptive Electrode Tissue Interface (ETI) Impedance Variations for Facial Paralysis Patients." Sensors 22, no. 5 (February 23, 2022): 1756. http://dx.doi.org/10.3390/s22051756.
Анотація:
Functional electrical stimulation (FES) is a safe, effective, and general approach for treating various neurological disorders. However, in the case of FES usage for implantable applications, charge balancing is a significant challenge due to variations in the fabrication process and electrode tissue interface (ETI) impedance. In general, an active charge balancing approach is being used for this purpose, which has limitations of additional power consumption for residual voltage calibration and undesired neurological responses. To overcome these limitations, this paper presents a reconfigurable calibration circuit to address both ETI variations and charge balancing issues. This reconfigurable calibration circuit works in two modes: An impedance measurement mode (IMM) for treating ETI variations and a hybrid charge balancing mode (HCBM) for handling charge balance issues. The IMM predicts the desired stimulation currents by measuring the ETI. The HCBM is a hybrid combination of electrode shorting, offset regulation, and pulse modulation that takes the best features of each of these techniques and applies them in appropriate situations. From the results, it is proved that the proposed IMM configuration and HCBM configuration have an optimal power consumption of less than 44 μW with a power ratio ranging from 1.74 to 5.5 percent when compared to conventional approaches.
13
Lippi-Green, Rosina. "The development of the directional adverb hin in an Alemannic dialect: From sociolinguistic marker to stereotype." American Journal of Germanic Linguistics and Literatures 3, no. 1 (January 1991): 31–50. http://dx.doi.org/10.1017/s1040820700000573.
Анотація:
ABSTRACTIn a small community of approximately 760 High Alemannic speakers, four reflexes of the MHG directional particle anhin co-occur: (aje), (ae), (ahe) and (ane) in a case of active variation leading to change. The distribution patterns indicate that the most active variants, (aje) and (ane), are evaluated differently by different segments of the community. In the adult population we find speakers for whom the variation is still active and subconscious as well as those for whom the change is complete or otherwise inactive. In contrast, the children and adolescents use the conservative variant as a sociolinguistic stereotype. This pattern suggests that the classical sociolinguistic definition of speech community may be inadequate.
14
Clerici, Davide, Francesco Mocera, and Aurelio Somà. "Experimental Characterization of Lithium-Ion Cell Strain Using Laser Sensors." Energies 14, no. 19 (October 2, 2021): 6281. http://dx.doi.org/10.3390/en14196281.
Анотація:
The characterization of thickness change during operation of LFP/Graphite prismatic batteries is presented in this work. In this regard, current rate dependence, hysteresis behaviour between charge and discharge and correlation with phase changes are deepened. Experimental tests are carried out with a battery testing equipment correlated with optical laser sensors to evaluate swelling. Furthermore, thickness change is computed analytically with a mathematical model based on lattice parameters of the crystal structures of active materials. The results of the model are validated with experimental data. Thickness change is able to capture variations of the internal structure of the battery, referred to as phase change, characteristic of a certain state of charge. Furthermore, phase change shift is a characteristic of battery ageing. Being able to capture these properties with sensors mounted on the external surface the cell is a key feature for improving state of charge and state of health estimation in battery management system.
15
Hon, Wei Jeat, Rachel Webster, and Christian Wolf. "Changing look active galactic nuclei in the MaNGA survey." Monthly Notices of the Royal Astronomical Society 497, no. 1 (July 7, 2020): 192–203. http://dx.doi.org/10.1093/mnras/staa1939.
Анотація:
ABSTRACT Changing look active galactic nuclei (CLAGNs) are rare cases of AGNs, where the continuum flux increases/decreases and the broad emission lines appear/disappear within short time-scales. These extreme changes challenge our understanding of accretion disc dynamics. We present a sample of four new CLAGNs at 0.026 < z < 0.107, which were found by cross-matching the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey with AGNs from the SDSS spectroscopic data base. Our results show that the selection criteria of $\gt \mathopen |0.5\mathclose |$ mag change in SDSS-g band is ineffective at lower redshifts. This is, in part, due to the fact that the g band is probing a different part of the AGNs spectral energy distribution at these redshifts. The bigger issue is that the galaxy continuum dominates the spectrum and thus overwhelms any variation of the AGNs continuum that might contribute to photometric variations. This suggests the need to use different methods for future low-redshift CLAGNs searches.
16
Simaremare, Mitra M., and Bambang Prihandoko. "Synthesis of Cathode Active Material LiMn0.5Fe0.5PO4F/C with Sintering Time Variation." Journal of Technomaterial Physics 4, no. 1 (February 28, 2022): 36–45. http://dx.doi.org/10.32734/jotp.v4i1.7758.
Анотація:
Research has been carried out on the synthesis of LiMn0.5Fe0.5PO4F/C, the cathode active materials with variations in sintering time. The process of producing the LiMn0,5Fe0,5PO4F/C as an active material in lithium battery cathodes has been successfully carried out by the first forming host structure and then infiltrating the lithium Li ions and the flour F ions. In this study, the synthesis was carried out with various sintering time, 6 hours, 8 hours and 10 hours. The raw materials used in this study are manganese dioxide (“MnO2”), iron (III) oxide (“Fe2O3”), lithium fluoride (“LiF”) and phosphoric acid (“H3PO4”) as the solvents. The synthesis was carried out at a calcination temperature of 720°C for 8 hours. The first mashed use a milling process for about 180 minutes, and placed into the oven, then mashed using a mortar. Then the Mn0.5Fe0.5PO4 sample was added with LiF, mixed with the milling process, placed into a drying oven and was varied with the sintering time of 6 hours for the first sample, 8 hours for the second sample and 10 hours for the third sample. As to produce LiMn0.5Fe0.5PO4F material, followed by carbon coating, namely tapioca and sugar (8%:4%). All three samples were calcined at a temperature of 720°C for 4 hours. The results of XRD analysis showed that the three samples did not experience a phase of change, however only shows a few differences in intensity. The results of FESEM analysis show that grain growth occurs vertically and horizontally due to the presence of the Mn and Fe, and with an exact enough amount of tapioca function as a carbon source to coat the active material, it help to creates pores in the powder so that the presence of these pores could provide an intercalation pathway for the lithium ions. At the end the results of the EIS analysis showed that the highest conductivity value of this study was 0.62 x 10-5 S/cm.
17
Dickstein, Michael J., Mark Duggan, Joe Orsini, and Pietro Tebaldi. "The Impact of Market Size and Composition on Health Insurance Premiums: Evidence from the First Year of the Affordable Care Act." American Economic Review 105, no. 5 (May 1, 2015): 120–25. http://dx.doi.org/10.1257/aer.p20151083.
Анотація:
Under the Affordable Care Act, individual states have discretion in how they define coverage regions, within which insurers must charge the same premium to buyers of the same age, family structure, and smoking status. We exploit variation in these definitions to investigate whether the size of the coverage region affects outcomes in the ACA marketplaces. We find large consequences for small and rural markets. When states combine small counties with neighboring urban areas into a single region, the included rural markets see 0.6 to 0.8 more active insurers, on average, and savings in annual premiums of between $200 and $300.
18
Rugma, S., B. Devu, and C. O. Sreekala. "Effect of Alkyl Substitution to the Active Layer Material for Improved Efficiency in Bilayer Organic Solar Cell." IOP Conference Series: Materials Science and Engineering 1225, no. 1 (February 1, 2022): 012022. http://dx.doi.org/10.1088/1757-899x/1225/1/012022.
Анотація:
Abstract Organic based thin film solar cells have achieved considerable power conversion efficiency (PCE). As there is a desire to the benefits of on-demand energy production, future world energy consumption will continue to rise. Bilayer organic solar cell has two active layers in between conductive electrodes. Present report, is a simulation study to compare the PCE of bilayer organic solar cells by varying one of its active layer material using General-Purpose Photovoltaic Device Model or GPVDM software. The materials used for active layer are MEH-M3EH-PPV, MEH-DOO-PPV, MEH-PPV and M3EH-PPV based on the degree of alkyl substitutions. Data of absorption spectrum, refractive index spectrum and photoluminescence spectrum are added as input and obtained the simulation results. Values of power conversion efficiencies, fill factor and other photovoltaic parameter values for each bilayer organic solar cell is obtained. Transmittance spectrum, reflectance spectrum, Current density-Voltage plot, variation of charge density and total charge density with applied voltage are attained from the simulation and compared. The results give out effect of side chain alkyl substitution on efficiency of bilayer organic solar cell. MEH-DOO-PPV with longest alkyl side chain substitution has maximum power conversion efficiency. This intuition helps to design suitable bilayer organic solar cell, which has got its relevant applications in the optoelectronics.
19
Li, Xiang, Shuo Tian, Zhifeng Liu, Na Xu, Runru Liu, Dejun Wang, and Wei Lü. "Optimization of electrode loading amount in lithium ion battery by theoretical prediction and experimental verification." AIP Advances 12, no. 11 (November 1, 2022): 115222. http://dx.doi.org/10.1063/5.0126103.
Анотація:
Lithium ion battery is a complex system, and any change in device parameters may significantly affect the overall performance. The prediction of battery behavior based on theoretical simulation is of great significance. In this work, the battery performance with LiNi1/3Co1/3Mn1/3O2 electrodes of different active material loading amounts was theoretically investigated, such as battery rate performance, capacity decay rate, energy and power density, SOC (State of Charge) change, temperature response, and heat source distribution. A 1D electrochemical–3D thermal coupling model was established, and the accuracy and predictability of the model were verified by experiments. An in-depth analysis of batteries under different discharge rates and batteries with different electrode loading amounts is carried out. The results show that the rate performance and capacity change with different electrode loading amounts, which is attributed to the variation in lithium ion diffusion. At the same time, the change in load affects the growth of lithium dendrites and the distribution of SOC, resulting in the thermal runaway of the battery and shortening the battery life.
20
Pevtsov, A. A., M. J. Hagyard, Z. Blehm, J. E. Smith, R. C. Canfield, T. Sakurai, and M. Hagino. "On a Cyclic Variation of the Hemispheric Helicity Rule." Highlights of Astronomy 13 (2005): 140. http://dx.doi.org/10.1017/s1539299600015409.
Анотація:
AbstractWe report the result of a study of magnetic helicity in solar active regions during 1980-2000. Using the vector magnetograms from four instruments (Haleakala Stokes Polarimeter, Marshall Space Flight Center, Mitaka Solar Flare Telescope and Okayama Observatory Solar Telescope) we calculated the force-free parameter α and computed a slope dα/dφ as the linear fit of α vs. latitude φ, using annual subsets of data. The hemispheric helicity rule can be expressed in terms of this slope as dα/dφ < 0. We find that each instrument exhibits change in sign of dα/dφ for some years. However, we do not see consistency between different instruments in regards to years disobeying the rule. We show that this inconsistency can be attributed to insufficient numbers of active regions in annual subsets of data. We conclude that the present data sets do not allow to make statistically significant inference about possible cyclic variation of the hemispheric helicity rule.For further discussion see Hagyard et al., 2003, ApJ, submitted.
21
Mayerl, C. J., K. E. Steer, A. M. Chava, L. E. Bond, C. E. Edmonds, F. D. H. Gould, B. M. Stricklen, T. L. Hieronymous, and R. Z. German. "The contractile patterns, anatomy and physiology of the hyoid musculature change longitudinally through infancy." Proceedings of the Royal Society B: Biological Sciences 288, no. 1946 (March 10, 2021): 20210052. http://dx.doi.org/10.1098/rspb.2021.0052.
Анотація:
All mammalian infants suckle, a fundamentally different process than drinking in adults. Infant mammal oropharyngeal anatomy is also anteroposteriorly compressed and becomes more elongate postnatally. While suckling and drinking require different patterns of muscle use and kinematics, little insight exists into how the neuromotor and anatomical systems change through the time that infants suckle. We measured the orientation, activity and contractile patterns of five muscles active during infant feeding from early infancy until weaning using a pig model. Muscles not aligned with the long axis of the body became less mediolaterally orientated with age. However, the timing of activation and the contractile patterns of those muscles exhibited little change, although variation was larger in younger infants than older infants. At both ages, there were differences in contractile patterns within muscles active during both sucking and swallowing, as well as variation among muscles during swallowing. The changes in anatomy, coupled with less variation closer to weaning and little change in muscle firing and shortening patterns suggest that the neuromotor system may be optimized to transition to solid foods. The lesser consequences of aspiration during feeding on an all-liquid diet may not necessitate the evolution of variation in neuromotor function through infancy.
22
Yuanzhang, Lin, Wei Xiaolei, and Zhang Hongqi. "Variation of Magnetic Fields and Electric Currents Associated with a Solar Flare." International Astronomical Union Colloquium 141 (1993): 446–49. http://dx.doi.org/10.1017/s0252921100029596.
Анотація:
It is well accepted that the source of energy for flares arises in the non-potential magnetic field from the dynamic evolution of active regions above the photosphere. So far, however, contradictory results have been suggested for the question of whether the occurrence of flares results in detectable changes of the magnetic fields and electric currents in the regions (Svestka, 1976)The early researches of Severny’s group showed that the longitudinal and transverse magnetic fields in active regions change evidently after flares, which are characterized by the simplification of magnetic configuration as well as the decrease of magnetic strength and gradient (Severny, 1962, 1969). Then, after studying the magnetograms of two active regions measured by the Kitt Peak’s magnetograph, Harvey suggested that there were changes in longitudinal magnetic fields with a time scale of hours, but they could be attributed to the global evolution of active regions and not directly related to the occurrence of flares (Harvey et al., 1970). Moreover, from the analyses of the Kitt Peak’s magnetograms for the big flare of 3B importance on 4 August 1972, Livingston indicated that the longitudinal magnetic fields before and after the flare remained unchanged (Livingston, 1973). On the other hand, from the study of the magnetograms obtained by the Big Bear Observatory’s video magnetograph before and after a 2B flare in the region McMath 13225 on 10 September 1970, Tanaka reached the conclusion that in weak field areas of less than 100G, the longitudinal field changed about 30–100% at the onset of the flare, and this change was associated with the flare (Tanaka, 1978). In recent years, some authors have investigated in detail the magnetograms of the well known region AR2372 on 6 April 1980 obtained with the video magnetograph of the Marshall Space Flight Center (Krall et al., 1982; Hagyard, 1984; Ding et al., 1985; Lin and Gaizauskas, 1987). Their results showed that the change of the magnetic fields occurred before a 1B/X2 flare. Therefore we have a rather confused picture about the variation of magnetic fields associated with flares.
23
Aoki, Ken, Dan P. Stephens, and John M. Johnson. "Diurnal variation in cutaneous vasodilator and vasoconstrictor systems during heat stress." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281, no. 2 (August 1, 2001): R591—R595. http://dx.doi.org/10.1152/ajpregu.2001.281.2.r591.
Анотація:
It is not clear whether the diurnal variation in the cutaneous circulatory response to heat stress is via the noradrenergic vasoconstrictor system or the nonadrenergic active vasodilator system. We conducted whole body heating experiments in eight male subjects at 0630 (AM) and 1630 (PM). Skin blood flow was monitored by laser-Doppler flowmetry at control sites and at sites pretreated with bretylium (BT) to block noradrenergic vasoconstriction. Noninvasive blood pressure was used to calculate cutaneous vascular conductance. The sublingual temperature (Tor) threshold for cutaneous vasodilation was significantly higher in PM at control and at BT-treated sites (both P < 0.01), suggesting the diurnal shift in threshold depends on the active vasodilator system. The slope of cutaneous vascular conductance as a percentage of its maximum with respect to Tor was significantly lower in AM at control sites only. Also, in the AM, the slope at control sites was significantly lower than that at BT-treated sites ( P < 0.05), suggesting that the diurnal change in the sensitivity of cutaneous vasodilation depends on vasoconstrictor system function. Overall, the diurnal variation in the reflex control of skin blood flow during heat stress involves both vasoconstrictor and active vasodilator systems.
24
Zhang, Qi, Yangying Zhou, Yaxuan Wei, Meiqian Tai, Hui Nan, Youchen Gu, Jianhua Han, Xuewen Yin, Jianbao Li та Hong Lin. "Improved phase stability of γ-CsPbI3 perovskite nanocrystals using the interface effect using iodine modified graphene oxide". Journal of Materials Chemistry C 8, № 7 (2020): 2569–78. http://dx.doi.org/10.1039/c9tc06465f.
25
Tannæs, Tone, Niek Dekker, Geir Bukholm, Jetta J. E. Bijlsma, and Ben J. Appelmelk. "Phase Variation in the Helicobacter pylori Phospholipase A Gene and Its Role in Acid Adaptation." Infection and Immunity 69, no. 12 (December 1, 2001): 7334–40. http://dx.doi.org/10.1128/iai.69.12.7334-7340.2001.
Анотація:
ABSTRACT Previously, we have shown that Helicobacter pylorican spontaneously and reversibly change its membrane lipid composition, producing variants with low or high content of lysophospholipids. The “lyso” variant contains a high percentage of lysophospholipids, adheres better to epithelial cells, and releases more proteins such as urease and VacA, compared to the “normal” variant, which has a low content of lysophospholipids. Prolonged growth of the normal variant at pH 3.5, but not under neutral conditions, leads to enrichment of lyso variant colonies, suggesting that the colony switch is relevant to acid adaptation. In this study we show that the change in membrane lipid composition is due to phase variation in the pldA gene. A change in the (C) tract length of this gene results in reversible frameshifts, translation of a full-length or truncatedpldA, and the production of active or inactive outer membrane phospholipase A (OMPLA). The role of OMPLA in determining the colony morphology was confirmed by the construction of an OMPLA-negative mutant. Furthermore, variants with an active OMPLA were able to survive acidic conditions better than variants with the inactive form. This explains why the lyso variant is selected at low pH. Our studies demonstrate that phase variation in thepldA gene, resulting in an active form of OMPLA, is important for survival under acidic conditions. We also demonstrated the active OMPLA genotype in fresh isolates of H. pylorifrom patients referred to gastroscopy for dyspepsia.
26
Heo, Jun-Woo, Sejun Hong, Seok-Gyu Choi, and Hyun-Seok Kim. "Analysis of Hyperabrupt and Uniform Junctions in GaAs for the Application of Varactor Diode." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7457–61. http://dx.doi.org/10.1166/jnn.2015.11140.
Анотація:
In this study, we present a GaAs varactor diode with a hyperabrupt junction for the enhancement of breakdown voltage and capacitance variation in a reverse bias state. The hyperabrupt doping profile in the n-type active layer is prepared in a controlled nonlinear manner, with the density of the dopants increasing towards the Schottky junction. The hyperabrupt GaAs varactor diode is fabricated and characterized for breakdown voltage and capacitance over the electric field, induced by an applied reverse bias voltage. A reduced value of the electric field is observed owing to the nonlinear behavior of the electric field at the hyperabrupt junction, although the device has a larger doping density at the Schottky junction. Furthermore, the capacitance ratio of the hyperabrupt junction diode is also improved. Variation in the device capacitance is affected by variation in the depletion region across the junction. Technology CAD is used to understand the experimental phenomena by considering the magnitude of charge density as a function of the doping profile. A higher breakdown voltage and greater capacitance modulation are shown in the hyperabrupt junction diode compared to the uniform junction diode.
27
Shen, I. Y. "A Variational Formulation, a Work-Energy Relation and Damping Mechanisms of Active Constrained Layer Treatments." Journal of Vibration and Acoustics 119, no. 2 (April 1, 1997): 192–99. http://dx.doi.org/10.1115/1.2889702.
Анотація:
The purposes of this paper are to formulate active constrained layer (ACL) damping treatments through a variational approach, to study the work-energy relation of ACL, and to identify damping mechanisms of ACL treatments. Application of the extended Hamilton principle to ACL results in the equations of motion of ACL and the charge equation of electrostatics for the piezoelectric constraining layer. The work-energy equation together with the charge equation shows that the power dissipated through the active damping is the product of the electric field and the axial velocity of the piezoelectric constraining layer at the boundaries. This unique feature suggests that a self-sensing and actuating piezoelectric constraining layer may be an appropriate design in dissipating vibration energy without causing instability. To identify the damping mechanisms, a sensitivity analysis shows that the effectiveness of ACL damping primarily depends on the active and passive damping forces transmitted to the vibrating structure through the viscoelastic layer. The active damping force transmitted depends on the controller transfer function as well as a system parameter, termed active damping sensitivity factor, which depends entirely on the configuration of the passive constrained layer and the sensor. Finally, numerical results on ACL beams are obtained to illustrate the theoretical predictions above.
28
Wang, Xueting, Yunchuang Wang, Meichao Wu, Ruopian Fang, Xi Yang, and Da-Wei Wang. "Ultrasonication-assisted fabrication of porous ZnO@C nanoplates for lithium-ion batteries." Microstructures 2, no. 3 (2022): 16. http://dx.doi.org/10.20517/microstructures.2022.11.
Анотація:
Lithium-ion batteries have made significant commercial and academic progress in recent decades. Zinc oxide (ZnO) has been widely studied as a lithium-ion battery anode due to its high theoretical capacity of 987 mAh g-1, natural abundance, low cost, and environmental friendliness. However, ZnO suffers from poor electronic conductivity and large volume variation during the battery discharge/charge process, leading to capacity deterioration during long-term cycling. Herein, porous ZnO@C nanoplates are developed to offer short ion diffusion pathways and good conduction networks for both Li ions and electrons. The porous nanoplates provide abundant active sites for electrochemical reactions with minimized charge transfer impedance. As a result, the porous ZnO@C nanoplates deliver higher performance for lithium-ion storage compared with a bare ZnO anode. Furthermore, with the introduction of reduced graphene oxide (rGO), the ZnO@C@rGO composite anode achieves a capacity of 229.3 mAh g-1 at a high current density of 2 A g-1.
29
Mohammadi Moghadam, Hooman, Ardashir Mohammadzadeh, Reza Hadjiaghaie Vafaie, Jafar Tavoosi, and Mohammad Hassan Khooban. "A type-2 fuzzy control for active/reactive power control and energy storage management." Transactions of the Institute of Measurement and Control 44, no. 5 (September 28, 2021): 1014–28. http://dx.doi.org/10.1177/01423312211048038.
Анотація:
This paper presents a new type-2 fuzzy logic control (T2FLC) for active/reactive power (AP/RP) regulation and energy storage management of an independent microgrid (MG). The case-study MG includes sporadic renewable sources that lead to significant frequency and voltage fluctuations in the network. The rules of suggested T2FLCs are tuned such that a fractional-order sliding condition can be satisfied. Also a new approach using square-root-cubature Kalman filter is designed to optimize the membership parameters of T2FLCs. Beside AP/RP power regulation, an electrical storage system (battery energy storage system (BESS)) is managed to produce the rated power, rather than a conventional generator. It makes the device frequency separate from the synchronous generator’s mechanical inertia. Nevertheless, a BESS has a power limit – it uses a synchronous generator to sustain the BESS charge state at a certain value. Sustainable energies achieve a voltage-damping impact by supplementing an AP/RP droop strategy procedure that considerably reduces voltage oscillation created by variation of its own output power. In various disturbed scenarios the good performance of the suggested controller and energy management system is shown.
30
Marchesini, Pierpaolo, Jonathan B. Ajo-Franklin, and Thomas M. Daley. "In situ measurement of velocity-stress sensitivity using crosswell continuous active-source seismic monitoring." GEOPHYSICS 82, no. 5 (September 1, 2017): D319—D326. http://dx.doi.org/10.1190/geo2017-0106.1.
Анотація:
The ability to characterize time-varying reservoir properties, such as the state of stress, has fundamental implications in subsurface engineering, relevant to geologic sequestration of [Formula: see text]. Stress variation, here in the form of changes in pore fluid pressure, is one factor known to affect seismic velocity. Induced variations in velocity have been used in seismic studies to determine and monitor changes in the stress state. Previous studies conducted to determine velocity-stress sensitivity at reservoir conditions rely primarily on laboratory measurements of core samples or theoretical relationships. We have developed a novel field-scale experiment designed to study the in situ relationship between pore-fluid pressure and seismic velocity using a crosswell continuous active-source seismic monitoring (CASSM) system. At the Cranfield, Mississippi, [Formula: see text] sequestration field site, we actively monitored seismic response for five days with a temporal resolution of 5 min; the target was a 26 m thick injection zone at approximately 3.2 km depth in a fluvial sandstone formation (lower Tuscaloosa Formation). The variation of pore fluid pressure was obtained during discrete events of fluid withdrawal from one of the two wells and monitored with downhole pressure sensors. The results indicate a correlation between decreasing CASSM time delay (i.e., velocity change for a raypath in the reservoir) and periods of reduced fluid pore pressure. The correlation is interpreted as the velocity-stress sensitivity measured in the reservoir. This observation is consistent with published laboratory studies documenting a velocity ([Formula: see text]) increase with an effective stress increase. A traveltime change ([Formula: see text]) of 0.036 ms is measured as the consequence of a change in pressure of approximately 2.55 MPa ([Formula: see text]). For [Formula: see text] total traveltime, the velocity-stress sensitivity is [Formula: see text]. The overall results suggest that CASSM measurements represent a valid technique for in situ determination of velocity-stress sensitivity in field-scale monitoring studies.
31
Chen, Gong. "Prediction of Peak Cylinder Pressure Variations Over Varying Inlet Air Condition of Compression-Ignition Engine." Journal of Engineering for Gas Turbines and Power 129, no. 2 (August 15, 2006): 589–95. http://dx.doi.org/10.1115/1.2431389.
Анотація:
Peak cylinder pressure (pmax) of a compression-ignition engine can be affected by the engine inlet air condition, such as its inlet air temperature (Ti) and pressure (pi). The variation of peak cylinder pressure due to varying inlet air temperature or pressure is analytically studied. A model is developed and simplified, and thus the variations of pmax can be predicted along with varying inlet air temperature or pressure. The analysis and prediction indicate that cylinder active compression ratio (CR) and intake air boost ratio (pm0∕pi0) play relatively significant roles in affecting the variation of pmax over inlet air temperature and pressure, and the pressure variation is proportional to CRk and ratio pm0∕pi0. Comparison between the predicted results using the simplified model and those from engine experiments shows a close agreement in both the trend and magnitude. The investigation and prediction also include modeling the variation in pmax due to varying the cylinder TDC clearance volume (Vc). The simplified model is presented and shows that the change in pmax versus varying Vc also depends on the cylinder compression ratio. It is indicated that for a certain change in the clearance volume, a higher compression-ratio configuration would produce a greater change in pmax than a lower one does, especially as the rest of the engine design and operating parameters remain unchanged.
32
Negrelli, C., L. Kraiselburd, S. Landau, and E. García-Berro. "Spatial variation of fundamental constants: Testing models with thermonuclear supernovae." International Journal of Modern Physics D 27, no. 09 (July 2018): 1850099. http://dx.doi.org/10.1142/s0218271818500992.
Анотація:
Since Dirac stated his Large Number Hypothesis the space-time variation of fundamental constants has been an active subject of research. Here we analyze the possible spatial variation of two fundamental constants: the fine structure constant [Formula: see text] and the speed of light [Formula: see text]. We study the effects of such variations on the luminosity distance and on the peak luminosity of Type Ia supernovae (SNe Ia). For this, we consider the change of each fundamental constant separately and discuss a dipole model for its variation. Elaborating upon our previous work, we take into account the variation of the peak luminosity of Type Ia supernovae resulting from the variation of each of these fundamental constants. Furthermore, we also include the change of the energy release during the explosion, which was not studied before in the literature. We perform a statistical analysis to compare the predictions of the dipole model for [Formula: see text] and [Formula: see text] variation with the Union 2.1 and JLA compilations of SNe Ia. Allowing the nuisance parameters of the distance estimator [Formula: see text] and the cosmological density matter [Formula: see text] to vary. As a result of our analysis, we obtain a first estimate of the possible spatial variation of the speed of light [Formula: see text]. On the other hand, we find that there is no significant difference between the several phenomenological models studied here and the standard cosmological model, in which fundamental constants do not vary at all. Thus, we conclude that the actual set of data of Type Ia supernovae does not allow to verify the hypothetical spatial variation of fundamental constants.
33
Eth, Oudaya, Bundhit Eua-Arporn, Surachai Chaitusaney, and Tu Van Dao. "Minimization of Voltage Deviation by Considering Active Power Change of Solar PV Plant." Applied Mechanics and Materials 781 (August 2015): 304–7. http://dx.doi.org/10.4028/www.scientific.net/amm.781.304.
Анотація:
For grid-connected photovoltaic systems, voltage profile is one of the most important issues to consider when the active power from PV plant changes because of variation of sunlight or night time. This paper proposes a method to calculate the optimal reactive power from solar PV plant to minimize voltage deviation when active power of one PV plant changes. By injecting of optimal reactive power, the voltage profile of all buses will be improved. The IEEE 33 bus system is selected to analyse the voltage deviation in various conditions [1].
34
Feres, Flavio H., Lucas Fugikawa Santos, and Giovani Gozzi. "Temperature and Electric Field Influence on the Electrical Properties of Light-Emitting Devices Comprising PEDOT:PSS/GPTMS/Zn2SIO4:Mn Composites." MRS Advances 3, no. 33 (2018): 1883–89. http://dx.doi.org/10.1557/adv.2018.179.
Анотація:
ABSTRACTIn the present study, we analyze the influence of temperature and active layer thickness on the electrical properties of electroluminescent devices comprising a polymeric conductive blend (poly(3,4 ethylenedioxythiophene):polystyrene sulfonate, PEDOT:PSS), an inorganic electroluminescent material (manganese doped zinc orthosilicate, Zn2SiO4:Mn) and an organosilicon material (3-glicidoxypropyltrimethoxysilane, GPTMS), manufactured at different weight ratios of the component materials. The devices were obtained by depositing the active layer by drop-casting onto ITO-coated (RF-sputtering) glass substrates and thermally evaporating gold top electrodes in high vacuum. The results show that 90 wt% Zn2SiO4:Mn is required to observe high electroluminescence from the fabricated devices and that the optimum performance (turn-on voltage of 33 V, luminous efficacy of 24 cd/A and maximum luminance of almost 2000 cd/m2) was achieve for a (9.5/0.5/90) (GPTMS/PEDOT:PSS/Zn2SiO4:Mn) weight ratio. The device turn-on voltage found to be as proportional to the thickness of the active layer, indicating that the electroluminescence occurs by a field-effect mechanism. The temperature variation in the 100-300 K range allowed us to develop a theoretical model for the device operation, where the charge carrier transport in the active layer is well described by the variable range hopping model, with luminous efficacy nearby independent of the temperature.
35
Zainuri, Mochamad, Triwikantoro, and Pelangi Az Zahra. "Active Materials LiFeSixP1-xO4/C as Lithium Ion Battery Cathode with Doping Variations Si Ions (0≤x≤0,06)." Key Engineering Materials 860 (August 2020): 75–80. http://dx.doi.org/10.4028/www.scientific.net/kem.860.75.
Анотація:
A cathode Lithium Ferro Phospate (LFP) composite material with variation doping ion Silicon (Si) with x = 0; 0,01; 0,03; 0.06 and carbon coating (LiFeSixP1-xO4/C) as lithium ion battery cathode were synthesized by a solid state reaction and wet milling methods. X-Ray Diffraction (XRD) pattern showed that the of olivine phase formed, and analysis characterization of Scanning Electron Microscopy (SEM) have shown average dimension particle of cathode in orde 1 micron. Analysis by Cyclic Voltammetry (CV) doping ion Si x = 0,03 have the best reversible electrochemical process than the other concentration, and have the highest charge and discharge capacity (78,745 mAh/g).
36
Santa-Ana-Tellez, Yared, Aukje K. Mantel-Teeuwisse, Hubert G. M. Leufkens, and Veronika J. Wirtz. "Seasonal Variation in Penicillin Use in Mexico and Brazil: Analysis of the Impact of Over-the-Counter Restrictions." Antimicrobial Agents and Chemotherapy 59, no. 1 (October 13, 2014): 105–10. http://dx.doi.org/10.1128/aac.03629-14.
Анотація:
ABSTRACTDuring 2010, Mexico and Brazil implemented policies to enforce existing laws of restricting over-the-counter sales of antibiotics. We determined if the enforcement led to more appropriate antibiotic use by measuring changes in seasonal variation of penicillin use. We used retail quarterly sales data in defined daily doses per 1,000 inhabitant-days (DDD/TID) from IMS Health from the private sector in Mexico and Brazil from the first quarter of 2007 to the first quarter of 2013. This database contains information on volume of antibiotics sold in retail pharmacies using information from wholesalers. We used interrupted time-series models controlling for external factors with the use of antihypertensives with interaction terms to assess changes in trend, level, and variation in use between quarters for total penicillin use and by active substance. The most used penicillin was amoxicillin, followed by amoxicillin-clavulanic acid and ampicillin (minimal use in Brazil). Before the restrictions, the seasonal variation in penicillin use was 1.1 DDD/TID in Mexico and 0.8 DDD/TID in Brazil. In Mexico, we estimated a significant decrease in the seasonal variation of 0.4 DDD/TID after the restriction, mainly due to changes in seasonal variation of amoxicillin and ampicillin. In Brazil, the seasonal variation did not change significantly, overall and in the breakdown by individual active substances. For Mexico, inappropriate penicillin use may have diminished after the restrictions were enforced. For Brazil, increasing use and no change in seasonal variation suggest that further efforts are needed to reduce inappropriate penicillin use.
37
Flavell, R. B. "Variation in structure and expression of ribosomal DNA loci in wheat." Genome 31, no. 2 (January 15, 1989): 963–68. http://dx.doi.org/10.1139/g89-168.
Анотація:
Ribosomal RNA genes are organised in tandem arrays at complex loci called nucleolus organisers. The structure of a locus and of a wheat rRNA gene is described in detail. Active or potentially active genes are in the nucleolus during interphase, while inactive genes are excluded from the nucleolus. Genetic variation exists within a species for the number of the rRNA genes at a locus and also for the structure of the intergenic, regulatory DNA. This variation can affect the activity of a locus, relative to that of another in the same cell and the proportion of the rRNA genes at a locus included in the nucleolus. The active loci are enriched with genes that are not methylated at specific CpG residues in the intergenic regulatory DNA and that are in a chromatin conformation accessible to DNase I. A model is presented that attempts to relate the structural variation between genes to the differential expression and nucleolar organisation of the rRNA genes at different loci. The model is based on the affinity of proteins, in limiting concentration, to specific regulatory DNA sequences. These sequences are subject to change as a result of mechanisms that can spread mutations through a locus. The resulting variation, which may not be eliminated by selection unless it is very deleterious and accounts for a large part of the total rDNA, may be one reason why plants maintain a large excess of ribosomal RNA genes.Key words: nucleolus, ribosomal RNA gene, methylation.
38
Versporten, Ann, Robin Bruyndonckx, Niels Adriaenssens, Niel Hens, Dominique L. Monnet, Geert Molenberghs, Herman Goossens, et al. "Consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials in the community, European Union/European Economic Area, 1997–2017." Journal of Antimicrobial Chemotherapy 76, Supplement_2 (July 1, 2021): ii45—ii59. http://dx.doi.org/10.1093/jac/dkab177.
Анотація:
Abstract Objectives Data on consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials were collected from 30 EU/European Economic Area (EEA) countries over two decades. This article reviews temporal trends, seasonal variation, presence of change-points and changes in the composition of main subgroups of tetracyclines, sulphonamides and trimethoprim and other antibacterials. Methods For the period 1997–2017, data on consumption of tetracyclines (ATC group J01A), sulphonamides and trimethoprim (ATC group J01E), and other antibacterials (ATC group J01X) in the community and aggregated at the level of the active substance, were collected using the WHO ATC/DDD methodology (ATC/DDD index 2019). Consumption was expressed in DDD per 1000 inhabitants per day and in packages per 1000 inhabitants per day. Consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials was analysed based on ATC-4 subgroups and presented as trends, seasonal variation, presence of change-points and compositional changes. Results In 2017, consumption of tetracyclines, sulphonamides and trimethoprim, and other antibacterials in the community expressed in DDD per 1000 inhabitants per day varied considerably between countries. Between 1997 and 2017, consumption of tetracyclines did not change significantly, while its seasonal variation significantly decreased over time. Consumption of sulphonamides and trimethoprim significantly decreased until 2006, and its seasonal variation significantly decreased over time. The consumption of other antibacterials showed no significant change over time or in seasonal variation. Conclusions Consumption and composition of tetracyclines, sulphonamides and trimethoprim, and other antibacterials showed wide variations between EU/EEA countries and over time. This represents an opportunity to further reduce consumption of these groups in some countries and improve the quality of their prescription.
39
Özdemir, Tanılay, Özgür Ekici, and Murat Köksal. "Numerical and experimental investigation of the thermal and electrical characteristics of a lithium ion cell." E3S Web of Conferences 321 (2021): 03007. http://dx.doi.org/10.1051/e3sconf/202132103007.
Анотація:
In this study, an electrochemical-thermal coupled model was developed to investigate the electrical and thermal behaviors of the commercial NCR18650b Li-ion cell during three different discharge rates. The 1-dimensional electrochemical model consists of a positive electrode, electrolyte, and a negative electrode and employs the related mass and charge transfer equations for both solid and liquid phases predicting the cell's voltage variation. The 3-dimensional thermal model involves a mandrel, an active battery part, and a shell. The thermal model solves the general heat diffusion equation and predicts the temperature variation of the cell. The results show that the predicted temperature-voltage profiles follow the same trend with experimental data and are consistent. The maximum calculated root mean square errors are obtained as 0.11 V for voltage, and 0.96 °C for temperature predictions. On the other hand, the maximum temperature differences within the cell was found to be 0.16 °C, 0.43 °C, and 1.29 °C after the 0.5 C, 1C and 1.5 C rate discharging processes, respectively. Finally, the results from the 3-dimensional thermal model reveal that the type of mandrel affects the temperature variation within the cell. However, the average surface temperature of the cell remains comparable for the investigated C rates.
40
Nagaraja, D., H. S. Geethanjali, N. R. Patil, F. M. Sanningannavar, R. A. Kusanur, and R. M. Melavanki. "Solvent Effect on the Fluorescence Properties of Two Biologically Active Thiophene Carboxamido Molecules." Mapana - Journal of Sciences 12, no. 1 (February 1, 2013): 49–68. http://dx.doi.org/10.12723/mjs.24.6.
Анотація:
The absorption and fluorescence spectra of two thiophene carboxamido molecules namely 2–( - trimethoxy phenyl) imino–3–N–ethylcarboxamido–4, 5, tetramethylene thiophene (X) and 2-( -N, N-dimethylaminophenyl) imino-3-(N- methylphenyl carboxamido)-4, 5, tetramethylene thiophene (Y) have been recorded at room temperature. The ground (mg) and excited (me) state dipole moments are estimated from Lippert, Bakhshiev, Kawski-Chamma-Viallet equations by using the variation of Stokes shift with microscopic solvent dielectric constant (e) and refractive index (n). The excited dipole moments were also estimated by using the variation of Stokes shift with microscopic empirical solvent polarity parameter and the values are compared. It was estimated that dipole moments of the excited state were higher than those of the ground state of both the molecules. Further, the change in dipole moment (Dm) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter .
41
Rozhanskiy, Fedor, and Elena Markus. "Dialectal variation in Votic: Jõgõperä vs. Luuditsa." Eesti ja soome-ugri keeleteaduse ajakiri. Journal of Estonian and Finno-Ugric Linguistics 6, no. 1 (June 9, 2015): 23–39. http://dx.doi.org/10.12697/jeful.2015.6.1.02.
Анотація:
This paper provides a comparison of two varieties of the Votic language. Based on field materials collected between 2001 and 2012 from the last speakers of Votic, we compiled a list of the most important phonetic and grammatical features that distinguish between Jõgõperä and Luuditsa varieties. The ten features are: the degree of apocope, the initial h, merging of allative and adessive cases, secondary geminates, illative singular forms, genitive and partitive plural markers, imperfect forms, the active participle marker, conditional markers, and negative pronominal forms. The analysis has shown that many differences can be explained by the influence of the neighbouring Ingrian language. There are more contact induced changes in the Luuditsa variety, which is probably the result of more intensive contacts with the Ingrian population in this village. The contemporary Luuditsa variety is a vivid example demonstrating that language change in the Lower Luga area was driven by convergent developments in no lesser degree than by divergent processes.
42
Cao, Junjun, Guoyong Leng, Peng Yang, Qingbo Zhou, and Wenbin Wu. "Variability in Crop Response to Spatiotemporal Variation in Climate in China, 1980–2014." Land 11, no. 8 (July 26, 2022): 1152. http://dx.doi.org/10.3390/land11081152.
Анотація:
As the population increases and climate extremes become more frequent, the pressure on food supply increases. A better understanding of the influence of climate variations on crop yield in China would be of great benefit to global food security. In this study, gridded, daily meteorological data and county-level annual yield data were used to quantify the climate sensitivity of corn, rice, and spring wheat yields, and identify the spatiotemporal variation relationship between climate and yields from 1980 to 2014. The results showed that rice and corn were more sensitive to climate variations than spring wheat, both spatially and temporally. Photosynthetic active radiation (PAR) was found to be beneficial to rice in northeast China and the Yangtze River basin, as well as corn in the south and spring wheat in Xinjiang, but not to rice in the south of the Yangtze River and spring wheat in the southeast coast. The temperature centroid shift was the main driving factor causing the movement of the centroid of the three crops. For every 1 km shift of the temperature centroid, the corn and rice yield centroids moved 0.97 km and 0.34 km, respectively. These findings improve our understanding of the impacts of climate variations on agricultural yields in different regions of China.
43
Yang, Haonan, Chichuan Jin, and Weimin Yuan. "Exploring the Link between the X-Ray Power Spectra and Energy Spectra of Active Galactic Nuclei." Astrophysical Journal 936, no. 1 (August 29, 2022): 36. http://dx.doi.org/10.3847/1538-4357/ac83bb.
Анотація:
Abstract Active galactic nuclei (AGN) are generally considered the scaled-up counterparts of X-ray binaries (XRBs). It is known that the power spectral density (PSD) of the X-ray emission of XRBs shows significant evolution with spectral state. It is not clear whether AGN follow a similar evolutionary trend, however, though their X-ray emission and the PSD are both variable. In this work, we study a sample of nine AGN with multiple long observations with XMM-Newton, which exhibit significant X-ray spectral variation. We perform Bayesian PSD analysis to measure the PSD shape and variation. We find that a large change in the X-ray energy spectrum (mainly the change in flux state) is often accompanied by a large change in the PSD shape. The emergence of a high-frequency break in the PSD also depends on the spectral state. Among the four sources with significant high-frequency PSD breaks detected, three show the break only in the high-flux state, while the remaining one shows it only in the low-flux state. Moreover, the X-ray rms variability in different spectral states of an AGN is found to vary by as much as 1.0 dex. These results suggest that the different variability properties observed are likely caused by different physical processes dominating different spectral states. Our results also indicate that the intrinsic PSD variation can introduce a significant fraction of the dispersion as reported for the correlations between various X-ray variability properties and the black hole mass.
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Lysnyansky, Innesa, Yael Ron, and David Yogev. "Juxtaposition of an Active Promoter to vsp Genes via Site-Specific DNA Inversions Generates Antigenic Variation inMycoplasma bovis." Journal of Bacteriology 183, no. 19 (October 1, 2001): 5698–708. http://dx.doi.org/10.1128/jb.183.19.5698-5708.2001.
Анотація:
ABSTRACT Mycoplasma bovis, the most important etiological agent of bovine mycoplasmosis, undergoes extensive antigenic variation of major and highly immunogenic surface lipoprotein antigens (Vsps). A family of 13 related but divergent vsp genes, which occur as single chromosomal copies, was recently found in the chromosome ofM. bovis. In the present study, the molecular mechanism mediating the high-frequency phase variation of two Vsps (VspA and VspC) as representatives of the Vsp family was investigated. Analysis of clonal isolates exhibiting phase transitions of VspA or of VspC (i.e., ON→OFF→ON) has shown that DNA inversions occur during Vsp phase variation. The upstream region of each vsp gene contains two sequence cassettes. The first (cassette no. 1), a 71-bp region upstream of the ATG initiation codon, exhibits 98% homology among all vsp genes, while the second (cassette no. 2), upstream of cassette no. 1, ranges in size from 50 to 180 bp and is more divergent. Examination of the ends of the inverted fragments during VspA or VspC phase variation revealed that in both cases, a change in the organization of vsp upstream cassettes involving three vsp genes had occurred. Primer extension and Northern blot analysis have shown that a specific cassette no. 2, designated A2, is an active promoter and that juxtaposition of this regulatory element to a silent vsp gene by DNA inversions allows transcription initiation of the recipient gene. Further genetic analysis revealed that phase variation of VspA or of VspC involves two site-specific DNA inversions occurring between inverted copies of a specific 35-bp sequence present within the conserved cassette no. 1. A model for the control of Vsp phase variation is proposed.
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Lee, Jiann-Shu, Hsing-Hsien Wu, and Ming-Zheng Yuan. "LUNG SEGMENTATION FOR CHEST RADIOGRAPH BY USING ADAPTIVE ACTIVE SHAPE MODELS." Biomedical Engineering: Applications, Basis and Communications 22, no. 02 (April 2010): 149–56. http://dx.doi.org/10.4015/s1016237210001876.
Анотація:
In this article, we propose an automatic lung segmentation method. We design an ROI-adjusted initial boundary derivation method to estimate a proper initial lung boundary for ASM deformation by deriving the translation and the scaling parameters from the lung ROI. An adaptive ASM, using k-means clustering and silhouette-based cluster validation technique, is proposed to adapt to the lung shape change so that the lung shape variation among people can be overwhelmed. The experimental results indicate that the performance of the proposed lung segmentation method is superior to the traditional ASM approach.
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Ross, Donald S., and Richmond J. Bartlett. "Charge fingerprints of forest organic horizons from north-eastern USA." Soil Research 35, no. 3 (1997): 553. http://dx.doi.org/10.1071/s96078.
Анотація:
The charge fingerprint procedure was used to characterise the exchange properties of high- organic forest soils from the north-eastern USA. Twenty-six Oa or A horizon samples were obtained from active research sites to provide samples with a range in carbon from 15·1 to 49·4% and pH (in 1 mM CaCl2) from 2·8 to 4·2. Fingerprints were similar to those developed for other variably charged soils except that significant quantities of exchangeable H+ were found and no appreciable anion exchange capacity was measured. The magnitude of the ‘base’ cation capacity (CECB) varied linearly with pH, averaging >50% change per unit pH change. A good estimate of the CECB was obtained from the sum of cations removed by a single extraction with 1·0 М choline chloride (slope 1·03, r2 = 0·91). Variations in exchangeable Al3+ or H+ with pH were related to the quantity found in untreated samples, probably because of the close association between exchangeable and organically complexed forms. The total CEC was closely related to the sum of cations removed by 0·1 M BaCl2 (slope 1·05, r2 = 0·96). Although low ionic strength may be difficult to maintain in low pH samples, the fingerprint method appears to allow precise interpolation of the organic soils’ exchange capacity at field pH.
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O'Neill, P., S. Davies, E. M. Fielden, L. Calabrese, C. Capo, F. Marmocchi, G. Natoli, and G. Rotilio. "The effects of pH and various salts upon the activity of a series of superoxide dismutases." Biochemical Journal 251, no. 1 (April 1, 1988): 41–46. http://dx.doi.org/10.1042/bj2510041.
Анотація:
The CuZn superoxide dismutases (SODs) from ox, sheep, pig and yeast were investigated by pulse radiolysis in order to evaluate the role of electrostatic interactions between O2.- and SOD proteins in the mechanism of action of the SOD enzymes. The protein net charge in this series varies, as evaluated by the protein pI values spanning over a large range of pH: 8.0 (sheep), 6.5 (pig), 5.2 (ox) and 4.6 (yeast). The amino acid sequences are largely conserved, with the three mammalian proteins being highly homologous and the yeast protein having some distinct variations in the region surrounding the active site. At pH 8.0 the activities of the SODs from various sources are similar, though the minor differences observed suggest that in the highly homologous mammalian series the most acidic protein is the most enzymically efficient one. The pH-dependences of the various activities in the pH range 7-12 are similar, and the related curves are best fitted by two pK values, which are approx. 9.2 and 11.0 for the mammalian enzymes and 9.1 and 11.4 for the yeast enzyme. The activities of the proteins at I 0.1 are decreased by approx. 20% when compared with the activity at I 0.02 at pH 8.5, whereas at pH above 10 the pH-dependence of the activity approaches that determined at I 0.02 and at pH 11.9 the activity is essentially independent of ionic strength. The dependence upon ionic strength also depends on the salt used, with perchlorate being more effective than phosphate or borate or Mops and still effective at pH above 10.5, where the effect of other salts becomes negligible. The dual and concerted dependence of the activities of different SODs on pH and salt concentration is explained with the encounter of O2.- with the active-site copper being governed by the protonation of two positively charged groups in the vicinity of the active site. The gradient between these localized charges and the rest of the protein may explain the different activities of the mammalian proteins at lower pH. On the basis of the sequence variation of the SODs examined it is not possible to definitely identify these groups. Likely candidates are conserved basic amino acid side chains in the vicinity (less than or equal to 1.2 nm) of the active site, i.e. Lys-134 and Arg-141, but co-ordination of OH- in the first copper co-ordination sphere may be an additional factor accounting for the higher pK.(ABSTRACT TRUNCATED AT 400 WORDS)
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Rapp, M., F. J. Lübken, and T. A. Blix. "Small scale density variations of electrons and charged particles in the vicinity of polar mesosphere summer echoes." Atmospheric Chemistry and Physics Discussions 3, no. 4 (July 4, 2003): 3469–91. http://dx.doi.org/10.5194/acpd-3-3469-2003.
Анотація:
Abstract. We present small scale variations of electron number densities and particle charge number densities measured in situ in the presence of polar mesosphere summer echoes. It turns out that the small scale fluctuations of electrons and negatively charged particles show a strong anticorrelation down to the smallest scales observed. Comparing these small scale structures with the simultaneously measured radar signal to noise profile, we find that the radar profile is well described by the power spectral density of both electrons and charged particles at the radar half wavelength (= the Bragg scale). Finally, we consider the shape of the power spectra of the observed plasma fluctuations and find that both charged particles and electrons show spectra that can be explained in terms of either neutral air turbulence acting on the distribution of a low diffusivity tracer or the fossil remnants of a formerly active turbulent region. All these results are consistent with the theoretical ideas by Rapp and Lübken (2003) suggesting that PMSE can be explained by a combination of active and fossil neutral air turbulence acting on the large and heavy charged aerosol particles which are subsequently mirrored in the electron number density distribution that becomes visible to a VHF radar when small scale fluctuations are present.
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Rapp, M., F. J. Lübken, and T. A. Blix. "Small scale density variations of electrons and charged particles in the vicinity of polar mesosphere summer echoes." Atmospheric Chemistry and Physics 3, no. 5 (September 16, 2003): 1399–407. http://dx.doi.org/10.5194/acp-3-1399-2003.
Анотація:
Abstract. We present small scale variations of electron number densities and particle charge number densities measured in situ in the presence of polar mesosphere summer echoes. It turns out that the small scale fluctuations of electrons and negatively charged particles show a strong anticorrelation down to the smallest scales observed. Comparing these small scale structures with the simultaneously measured radar signal to noise profile, we find that the radar profile is well described by the power spectral density of both electrons and charged particles at the radar half wavelength (=the Bragg scale). Finally, we consider the shape of the power spectra of the observed plasma fluctuations and find that both charged particles and electrons show spectra that can be explained in terms of either neutral air turbulence acting on the distribution of a low diffusivity tracer or the fossil remnants of a formerly active turbulent region. All these results are consistent with the theoretical ideas by Rapp and Lübken (2003) suggesting that PMSE can be explained by a combination of active and fossil neutral air turbulence acting on the large and heavy charged aerosol particles which are subsequently mirrored in the electron number density distribution that becomes visible to a VHF radar when small scale fluctuations are present.
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Cook, Erik P., and Daniel Johnston. "Active Dendrites Reduce Location-Dependent Variability of Synaptic Input Trains." Journal of Neurophysiology 78, no. 4 (October 1, 1997): 2116–28. http://dx.doi.org/10.1152/jn.1997.78.4.2116.
Анотація:
Cook, Erik P. and Daniel Johnston. Active dendrites reduce location-dependent variability of synaptic input trains. J. Neurophysiol. 78: 2116–2128, 1997. We examined the hypothesis that dendritic voltage-gated channels can reduce the effect synaptic location has on somatic depolarization in response to patterns of short synaptic trains (referred to as location-dependent variability). Three computer models of a reconstructed hippocampal CA1 cell, each of increasing realism and complexity, were used. For each model, the goal was to identify the dendritic composition that best reduced the location-dependent variability. The first model was linear and a single parameter, dendritic membrane conductance ( G Dm , where R m = 1/ G Dm ), was varied. Surprisingly, a negative G Dm minimized the location-dependent variability. Superposition of the synaptic inputs showed that, compared with passive dendrites, active dendrites increase the mean of the individual responses while decreasing the variance between synapses at different locations. Active dendrites compensate the three components of passive cable signal interference that increase with distance from the soma: the accumulation of charge on dendritic membrane capacitance, the escape of charge across synaptic and nonsynaptic dendritic membrane conductances, and the reduction in synaptic charge entry due to increased depolarization of dendrites located farther from the soma. We also found that the entire active dendritic tree contributes charge to any one active synapse. The second model contained an artificial voltage-dependent current ( I boost) added to passive apical dendrites. The optimal amount of I boost that minimized location-dependent variability was found to be independent of the strength of individual synaptic inputs but inversely related to the synaptic duration. In the third model, realistic T-type Ca2+ and persistent Na+ channel models were added to passive dendrites and numerically fit to reproduce the effects of I boost. Both realistic currents minimized synaptic variability. The densities for the realistic dendritic currents were not uniform but showed subtle variations and a slight reduction with distance from the soma. A heteroassociative memory network also was modeled to demonstrate the important relationship between location-dependent variability and memory recall performance. Compared with passive dendrites, active dendrites increased memory storage by reducing recall errors. These simulations demonstrate that active dendrites can minimize the cable properties of passive dendrites and enhance the soma's ability to determine the strength of the synaptic input. These models predict dendrites that minimize location-dependent variability will have an overall negative slope conductance I-V relationship that is tuned precisely.