To see the other types of publications on this topic, follow the link: Spherical calorimeter.
Journal articles on the topic 'Spherical calorimeter'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Spherical calorimeter.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Kindin, V. V., M. B. Amelchakov, N. S. Barbashina, et al. "A Cherenkov Water Calorimeter Based on Quasi-Spherical Modules." Instruments and Experimental Techniques 61, no. 5 (2018): 649–57. http://dx.doi.org/10.1134/s0020441218050068.
Full text
2
Naziyev, J. "ACCOUNT FOR THE INFLUENCE OF THE ECCENTRICITY OF SPHERICAL INSALLATIONS FOR MEASURING THERMAL CONDUCTIVITY OF SUBSTANCES." Scientific heritage, no. 96 (September 5, 2022): 71–73. https://doi.org/10.5281/zenodo.7049648.
Full textAbstract:
To calculate thermal conductivity using spherical measuring instruments, it is necessary to know the heat flux and temperature difference between symmetrical spherical working surfaces. For the case of symmetric spherical surfaces, the calculation equation is well known. In this work, the influence of the eccentricity of the spherical surfaces of devices in calculating the thermal conductivity is theoretically determined.
3
Sitepu, Husin. "In situ structural and texture analyses of monoclinic phase for polycrystalline Ni-rich Ti49.86Ni50.14 alloy from neutron diffraction data." Powder Diffraction 23, no. 1 (2008): 35–40. http://dx.doi.org/10.1154/1.2839141.
Full textAbstract:
Phase transformation temperatures of a polycrystalline Ni-rich Ti49.86Ni50.14 shape memory alloy were investigated using a differential scanning calorimeter. In situ structural and texture analyses of the monoclinic Ti49.86Ni50.14 were investigated using neutron powder diffractometer technique. Differential scanning calorimeter results showed that this Ni-rich alloy has a one-step cubic to monoclinic martensitic phase transformation on cooling and a one-step monoclinic to cubic transformation on heating. In situ high-resolution neutron powder diffraction data of the monoclinic phase from low temperatures to room temperature on heating are consistent with the differential scanning calorimeter’s heating results. In addition, the refined monoclinic crystal structure parameters for all neutron diffraction data sets agree satisfactorily with single-crystal X-ray diffraction results. The multiple-data-set capabilities of the GSAS Rietveld refinement program, with a generalized spherical-harmonics description was used successfully to extract the texture description directly from a simultaneous refinement using 52 time-of-flight monoclinic neutron diffraction patterns, taken from a polycrystalline sample held in 13 orientations inside the diffractometer.
4
Xu, Wenzheng, Jie Wang, Jinyu Peng, Xin Liang, Hao Li, and Jingyu Wang. "Study on the Influencing Factors of Ultrafine Spherical RDX during Spray Drying with Low Speed." Journal of Nanomaterials 2019 (March 14, 2019): 1–10. http://dx.doi.org/10.1155/2019/7915129.
Full textAbstract:
Cyclotrimethylene trinitramine (RDX, C3H6N6O6) with the size of 400 to 600 nm was prepared by low-speed spray-drying method. Meanwhile, the crystal morphology, particle size, crystal structure, thermal decomposition properties, and impact sensitivity properties of the raw materials of RDX and the prepared ultrafine spherical RDX were characterized by scanning electron microscope (SEM), laser particle size analyzer (LPSA), X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and impact sensitivity instrument. The factors affecting experimental results were discussed; the size and morphology of RDX crystals were found to be affected by drying temperature, spray speed, and RDX mass fraction in solution. The optimal preparation conditions for the ultrafine spherical RDX were studied, and the results showed that the RDX particles with the best morphology and particle uniformity were prepared when the drying temperature was 90°C, spray speed was 1 ml/min, and the RDX mass fraction in solution was 4%. As a result, the activation energy (Ea) of the ultrafine spherical RDX was lower than that of raw RDX by 24.52 KJ·mol-1, and the characteristic drop (H50) of the ultrafine spherical RDX was higher by 35.3 cm.
5
Wu, Wei-Yi, and Chie-Shaan Su. "Recrystallization and Production of Spherical Submicron Particles of Sulfasalazine Using a Supercritical Antisolvent Process." Crystals 8, no. 7 (2018): 295. http://dx.doi.org/10.3390/cryst8070295.
Full textAbstract:
In this study, the recrystallization and production of spherical submicron particles of sulfasalazine, an active pharmaceutical ingredient (API), were performed using the supercritical antisolvent (SAS) process, a nonconventional crystallization technique. Sulfasalazine was dissolved in tetrahydrofuran (THF), and supercritical carbon dioxide (CO2) served as the antisolvent. The effects of operating parameters on the SAS process, including the operating pressure, solution concentration, solution flowrate, CO2 flowrate, and spraying nozzle diameter, at two operating temperatures were examined. The solid-state characteristics of sulfasalazine before and after the SAS process, including particle size, crystal habit, and crystal form, were analyzed using a scanning electron microscope (SEM), powder X-ray diffractometer (PXRD), and differential scanning calorimeter (DSC). A higher operating temperature, intermediate operating pressure, higher CO2 flowrate, and lower solution flowrate are recommended to obtain spherical particles of sulfasalazine. The effects of the solution concentration and spraying nozzle diameter on the SAS process were negligible. Under optimal conditions, spherical sulfasalazine crystals with a mean size of 0.91 μm were generated, and this study demonstrated the feasibility for tuning the solid-state characteristics of API through the SAS process.
6
Khomyakov, V. A., V. V. Kindin, V. D. Burtsev, et al. "Study of Characteristics of the Quasi-spherical Measurement Modules of the Cherenkov Water Calorimeter NEVOD." Physics Procedia 74 (2015): 442–48. http://dx.doi.org/10.1016/j.phpro.2015.09.223.
Full text
7
González-Durán, José Eli Eduardo, Juvenal Rodríguez-Reséndiz, Juan Manuel Olivares Ramirez, Marco Antonio Zamora-Antuñano, and Leonel Lira-Cortes. "Finite-Element Simulation for Thermal Modeling of a Cell in an Adiabatic Calorimeter." Energies 13, no. 9 (2020): 2300. http://dx.doi.org/10.3390/en13092300.
Full textAbstract:
This research obtains a mathematical formulation to determine the heat transfer in a transient state, in a calorimeter cell, considering an adiabatic system. The development of the cell was established and the mathematical model was transiently solved, which approximated the physical phenomenon under the cell operation. A numerical method for complex geometries was used to validate performance. The results obtained in the transient heat transfer in a cylinder under boundary and initial conditions were compared using an analytical solution and numerical analysis employing the finite-element method with commercial software. The study from the temperature distribution can afford, selection between a cylindrical and spherical geometry, design criteria that are generated by changing parameters such as dimension, temperature, and working fluids to develop an adiabatic calorimeter to measure the heat capacity in fluids. We show the mathematical solution with its initial and boundary conditions as well as a comparison with a numerical solution for a cylindrical cell with a maximum error from 0.075% in the temperature value, along with a theoretical and numerical analysis for a temperature difference of 1 °C.
8
Hu, Shi Xiang, Ya Li, and Xin Min Wu. "The Standard Formation Enthalpies of Spherical ZnO Nano-Particles: Size Matters." Advanced Materials Research 1118 (July 2015): 62–66. http://dx.doi.org/10.4028/www.scientific.net/amr.1118.62.
Full textAbstract:
Four kinds of spherical nanoZnO particles with diameter of 20 nm, 30 nm, 40 nm and 50 nm were characterized by XRD and SEM. Based on a thermodynamic cycle, the standard molar formation enthalpies (ΔfHm) were measured and calculated by the RD496-2000 micro-calorimeter. They are (-328.41±1.575) kJ·mol–1(50 nm), (-323.11 ± 1.579) kJ·mol–1(40 nm), (-313.47 ± 1.581) kJ·mol–1(30 nm), (-307.66 ±1.616) kJ·mol–1(20 nm). The results show that nanosized ZnO has higher standard molar formation enthalpy compared to that of bulk ZnO (–350.46 ± 0.27 kJ·mol–1), indicating that the stability of nanosized ZnO decreases. More interestingly, the results show that the smaller size of the ZnO nanoparticles, the higher standard molar formation enthalpy was obtained. This indicates that ZnO nanoparticles get destabilized when the size decreases. The value of the standard molar formation enthalpies y (kJ·mol–1) and size x (nm) can be approximately described by a linear function of y = –0.7189 x –293.
9
Sitepu, Husin. "Structural refinement of neutron powder diffraction data of two-stage martensitic phase transformations in Ti50.75Ni47.75Fe1.50 shape memory alloy." Powder Diffraction 22, no. 3 (2007): 209–18. http://dx.doi.org/10.1154/1.2754715.
Full textAbstract:
Transformation behaviors of the technologically important polycrystalline Ti50.75Ni47.75Fe1.50 shape memory alloy were investigated using differential scanning calorimeter (DSC) and powder diffraction techniques. DSC revealed that there are two-stage (i.e., cubic→trigonal→monoclinic) martensitic phase transformations on cooling and a one-step transformation (monoclinic→cubic) on heating. In situ structural refinement of cubic→trigonal→monoclinic on cooling was carried out using the D1A high-resolution neutron powder diffractometer at the Institut Laue-Langevin Neutrons for Science in Grenoble, France. Results showed that the phases involved during the phase transition are consistent with the differential scanning calorimeter cooling curve, and the refined crystal structure parameters obtained from Rietveld refinements with the generalized spherical harmonic description agreed reasonably well with X-ray single-crystal data. Subsequently, a combined neutron and synchrotron structural refinement for each phase was conducted because the trial refinements initially using only the synchrotron data of trigonal phase yielded a false minimum with a somewhat high goodness-of-fit χ2. Results obtained from the combined neutron and synchrotron data of the cubic, trigonal, and monoclinic phases show that the same minimum goodness-of-fit indices were always obtained.
10
Sitepu, H., and Heinz Günter Brokmeier. "Quantitative Texture Analysis and Phase Fraction of Nickel-Titanium Shape Memory Alloys by Means of Neutron Diffraction." Materials Science Forum 443-444 (January 2004): 267–70. http://dx.doi.org/10.4028/www.scientific.net/msf.443-444.267.
Full textAbstract:
The orientation distribution function (ODF) of the textured polycrystalline nickel titanium (NiTi) shape memory alloys (SMAs) was determined from the measured austenitic (B2)pole-figures by neutron diffraction. The texture results showed that neutron diffraction is an excellent tool to investigate the minor variation in the texture of NiTi alloys, which is very sensitive to the variation of the content of nickel in the materials. Moreover, the alloys crystallographic phase fraction and texture were calculated from Rietveld refinement with generalized spherical harmonic (GSH) description for the measured complete neutron powder diffraction (ND) spectrum, rather than a few isolated peaks, during in-situ temperature-induced martensitic transformation. The phase fraction results are consistent with the differential scanning calorimeter (DSC) curves.
11
Zhang, Rong Hua, Bao Hong Zhu, Yon Gan Zhang, and Biao Wu. "Effect of Temperature on Microstructure and Mechanical Properties of Spray Forming Al-8.5Fe-1.3V-1.7Si Alloys." Advanced Materials Research 287-290 (July 2011): 43–48. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.43.
Full textAbstract:
Heat-resistant Al-8.5Fe-1.3V-1.7Si alloys were prepared by spray forming technique. The effect of temperature on microstructure and mechanical properties of the alloys was studied by optical microscope(OM), transmission electron microscope(TEM) with energy dispersive spectrometer(EDS), X-ray diffraction(XRD), differential scanning calorimeter(DSC) in this paper. The research results show that the microstructure of the material doesn’t change obviously after being hold for 3 hours at 420°C temperature. When the temperature is over 420°C, the second coarse phases are found in the alloy. The study on the microstructure of the alloy exposed at 400°C for 100 hours shows that the alloy has excellent high temperature stability. And the main second phase in the alloy is spherical a-Al12(Fe,V)3Si, with a little other phases such as Al13Fe4, Al6Fe, Al9FeSi3 and so on.
12
Jia, Xinlei, Wenshan Peng, Lanjuan Xu, et al. "Preparation, High-Density Spherical, and Low Sensitivity of RDX/NC/PMMA Composite Particles." Journal of Nanomaterials 2021 (October 18, 2021): 1–8. http://dx.doi.org/10.1155/2021/1650939.
Full textAbstract:
In order to reduce the mechanical sensitivity of cyclotrimethylenetrinitramine (RDX) and improve its energy density, spherical RDX/PMMA/NC composite particles were prepared by spray drying method, selecting polymethyl methacrylate (PMMA, hydrocarbon binder) with excellent mechanical properties and nitrocellulose (NC, energy-containing binder) with higher density as the desensitizing shell material, RDX as the core material. PMMA/NC composite particles of the same component were prepared by a simple solvent evaporation method at the same time. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC), respectively. Moreover, the safety performance has been qualitatively tested and analyzed through impact sensitivity and friction sensitivity. The results show that the addition of NC/PMMA binder would not change the original crystal structure of RDX, and the RDX/NC/PMMA composites fabricated by spray drying presented spherical particles with uniform distribution and smooth surface. The Tp0 of RDX/NC/PMMA composite particles increased from 220.3°C to 228.2°C, improving the thermal decomposition performance. The H50 rose from 29.32 cm to 84.3 cm, and the probability of friction explosion decreased from 96% to 8%, significantly enhancing the safety performance. In short, the RDX/NC/PMMA composites prepared via the spray drying method and the improvement of their performance have positive significance for the development of explosives in pursuit of high energy and low sensitivity.
13
Jia, Xinlei, Lixin Wei, Xuewen Liu, et al. "Fabrication and Characterization of Submicron Scale Spherical RDX, HMX, and CL-20 without Soft Agglomeration." Journal of Nanomaterials 2019 (November 26, 2019): 1–8. http://dx.doi.org/10.1155/2019/7394762.
Full textAbstract:
In this study, a novel spray drying-assisted self-assembly (SDAS) technology was proposed to prepare submicron elemental explosives with good morphology, uniform dispersion, and low sensitivity and spherical submicron RDX, HMX, and CL-20 particles without soft agglomeration were fabricated via such a method. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). Moreover, safety performance was analyzed by qualitative testing of impact sensitivity and friction sensitivity. The XRD analysis demonstrated that HMX and CL-20 refined by SDAS maintained the crystal structure of β-HMX and ε-CL-20 before and after refinement, whereas the HMX crystal structure after spray recrystallization refinement was transformed from β-HMX to α-HMX. The DSC results indicated that the thermal decomposition peak temperature of the three particles refined by the SDAS technology had a minimum advancement, and the thermal stability of the particles was relatively superior. More importantly, the H50 of the RDX, HMX, and CL-20 refined by this novel method was increased to 48.3 cm, 44.6 cm, and 31.1 cm, and the probability of friction explosion was decreased to 62%, 62%, and 80%, respectively, thus significantly improving the safety performance as compared with the sample refined by spray recrystallization.
14
Krekhno, Roman V., Alexander P. Safronov, Anna I. Beketova, and Igor V. Beketov. "Electomagnetic absorption of composites based on epoxy resin and metallic iron nanoparticles." EPJ Web of Conferences 185 (2018): 04025. http://dx.doi.org/10.1051/epjconf/201818504025.
Full textAbstract:
The heat losses originated from the electro-magnetic absorption in magnetic epoxy-based composites with embedded metallic iron nanoparicles were studied by Calvet microcalorimetry. Iron magnetic nanoparticles (MNPs) were synthesized by electrical explosion of wire (EEW) method; they were non-agglomerated, spherical in shape and had a weight average diameter 85 nm. Composites based on the cured epoxy-dian resin contained MNPs in weight content varying from 10% up to 70% . To study the heat loss in alterating magnetic field commercial Calvet microcalorimeter was equiped by two coils in the serial connection placed in the calorimeter cells; one of the coils contained a sample of composite the other was a reference. The electromagnetic adsorption was studied in the alternating magnetic field up to 1700 A /m in 67 – 214 kHz frequency range. The measured values of the specific power losses revealed linear dependence on iron MNPs content in composite and non-linear increasing function of the field frequency.
15
Li, Ji Hang, Dong Jian Shi, Na Hu, Wei Fu Dong, Jun Feng Li, and Ming Qing Chen. "Synthesis and Characterization of a Novel Biodegradable Polymer with Fluorescence Property." Advanced Materials Research 197-198 (February 2011): 21–26. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.21.
Full textAbstract:
In this paper, a novel biodegradable and fluorescent polymer: fluorescein-polylactide (FL-PLA) was synthesized by FL and lactide in the method of ring-opening polymerization with the catalysis of Sn(Oct)2under 130°C . The structure and molecular weight of FL-PLA were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR) spectroscopy, and gel permeation chromatography (GPC). The molecular weight of FL-PLA increased from 9.03×103to 21.24×103with decreasing the amount of FL and kept a narrow distribution. The result of differential scanning calorimeter (DSC) showed that Tgincreased from 52 to 72°C with increasing the molecular weight of polymer. Moreover, the average number content of FL in each molecular chain decreased from 0.96 to 0.81 with decrement of the amount of FL. Furthermore, FL-PLA showed the fluorescence property, and the fluorescence intensity could be controlled by the amount of FL. The FL-PLA nanoparticles were prepared by mixing the good and poor solvent, and the diameter was about 3 μm with regular spherical morphology.
16
Yu, Xiaokun, Jingde Luan, Wei Chen, and Jialu Tao. "Preparation and Performance of Microencapsulated Phase Change Material with Paraffin Core and SiO2 Shell for High Latent Heat and Low Heat Loss by Sol–Gel Method." Nano 15, no. 12 (2020): 2050156. http://dx.doi.org/10.1142/s1793292020501568.
Full textAbstract:
Microencapsulated phase change materials (MicroPCM) were prepared via sol–gel method using paraffin as heat storage core and silica as inorganic shell. The morphology feature, chemical structure, thermal properties and thermal stability of MicroPCM were characterized by the field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FTIR), the differential scanning calorimeter (DSC), simultaneous thermal analyzer (STA) and the thermal conductivity meter. The results indicated that MicroPCM were spherical in shape with the shell thickness in the range from 236[Formula: see text]nm to 303[Formula: see text]nm. The stirring speed and TEOS dosage were key factor on the latent heat and supercool effect of MicroPCM. The maximum latent heat of MicroPCM was 240.2[Formula: see text][Formula: see text] with the heat loss of only 0.2[Formula: see text][Formula: see text] in phase transformation when it was prepared at the stirring speed of 400[Formula: see text]r/min and TEOS dosage of 20[Formula: see text]ml. MicroPCM was a promising material for thermal energy storage (TES).
17
Prasad, Akepogu, Mallavarapu Umamahesh, Gopiredddy Venkata Subba Reddy, Seetha Jaswanth, Gollapudi Venkata Ramanamurthy, and Duddela Varaprasad. "Green Synthesis of Antibacterial Cotton Nanocomposites with In Situ Generation of Copper Nanoparticles Using Senna auriculata Leaf Extract as Reductant." Advanced Science, Engineering and Medicine 12, no. 5 (2020): 672–79. http://dx.doi.org/10.1166/asem.2020.2572.
Full textAbstract:
Copper nanoparticles (CuNPs) were bio synthesized instantaneously in nanocomposite cotton fabrics (NCFs), utilizing aqueous Senna auriculata (SA) plant leaves solution as reductant. These NCFs with in situ generation of CuNPs were analyzed with different spectrophotometers such as Scanning Electron Microscope (SEM) combined with electron dispersive X-ray (EDX), Fourier transform infrared (FTIR), Thermogravimetric and Derivative thermogravimetric analysis (TGA and DTA), X-ray diffractometer (XRD) and Differential scanning calorimeter (DSC). The formed CuNPs were tested for their antibacterial and mechanical properties. The SEM results revealed that the bio synthesized CuNPs were spherical in shape and most of them with a mean size of 100 nm. The XRD studies explained the crystalline nature of CuNPs. These NCFs exhibited high thermal stability, good induced mechanical properties and acted as pathogenic killing agent against Gram positive and Gram negative bacteria. The Young's modulus value was found to be 65.81 MPa. The enhanced properties and immediate generation of CuNPs in NCFs can be utilized in medical applications such as antibacterial beds in hospitals, napkins and to make packing materials.
18
Huo, Xianliang, and Shujun Wang. "Novel method for microencapsulation of eutectic hydrated salt." E3S Web of Conferences 360 (2022): 01054. http://dx.doi.org/10.1051/e3sconf/202236001054.
Full textAbstract:
Phase change materials (PCMs), as latent thermal energy storage, have received plenty of attention in recent decades due to their excellent performance in energy conservation. Inorganic hydrated salts have many advantages over organic phase change materials, such as higher thermal storage density, low cost, nontoxicity and nonflammability. This work presents a simple and environmentally friendly method for the preparation of microcapsules with inorganic hydrated salts as core materials. Microcapsule using EHS composed of SSD and DHPD as core material and EC/ABS as shell material has been prepared and investigated by various characterization techniques. The scanning electron microscope (SEM) results indicate that the microcapsules are basically spherical with a core-shell structure. In addition, Fourier-transform infrared spectroscopy (FT-IR) analysis results suggest that the microcapsules are only the physical coating of composite shell material to core material. Furthermore, the phase transition enthalpy is 168.3 J/g according to the differential scanning calorimeter (DSC) analysis. Besides, the method of microencapsulation may be extended to other liquid hydrates salts at room temperature.
19
Folorunso, Oladipo, Yskandar Hamam, Rotimi Sadiku, Suprakas Sinha Ray, and Neeraj Kumar. "Investigation and Modeling of the Electrical Conductivity of Graphene Nanoplatelets-Loaded Doped-Polypyrrole." Polymers 13, no. 7 (2021): 1034. http://dx.doi.org/10.3390/polym13071034.
Full textAbstract:
In this study, a hybrid of graphene nanoplatelets with a polypyrrole having 20 wt.% loading of carbon-black (HGPPy.CB20%), has been fabricated. The thermal stability, structural changes, morphology, and the electrical conductivity of the hybrids were investigated using thermogravimetric analyzer, differential scanning calorimeter, X-ray diffraction analyzer, scanning electron microscope, and laboratory electrical conductivity device. The morphology of the hybrid shows well dispersion of graphene nanoplatelets on the surface of the PPy.CB20% and the transformation of the gravel-like PPy.CB20% shape to compact spherical shape. Moreover, the hybrid’s electrical conductivity measurements showed percolation threshold at 0.15 wt.% of the graphene nanoplatelets content and the curve is non-linear. The electrical conductivity data were analyzed by comparing different existing models (Weber, Clingerman and Taherian). The results show that Taherian and Clingerman models, which consider the aspect ratio, roundness, wettability, filler electrical conductivity, surface interaction, and volume fractions, closely described the experimental data. From these results, it is evident that Taherian and Clingerman models can be modified for better prediction of the hybrids electrical conductivity measurements. In addition, this study shows that graphene nanoplatelets are essential and have a significant influence on the modification of PPy.CB20% for energy storage applications.
20
Nayfeh, Yousof, Syed Muhammad Mujtaba Rizvi, Baha El Far, and Donghyun Shin. "In Situ Synthesis of Alumina Nanoparticles in a Binary Carbonate Salt Eutectic for Enhancing Heat Capacity." Nanomaterials 10, no. 11 (2020): 2131. http://dx.doi.org/10.3390/nano10112131.
Full textAbstract:
A binary carbonate salt eutectic (Li2CO3-K2CO3)-based nanofluid was in situ synthesized by mixing with a precursor material, aluminum nitrate nonahydrate (Al(NO3)3·9H2O). Thermal decomposition of the precursor was successfully carried out to synthesize alumina (Al2O3) nanoparticles at 1 wt.% concentration. A thermogravimetric analysis (TGA) confirmed a complete thermal decomposition of aluminum nitrate nonahydrate to alumina nanoparticles. A transmission electron microscope (TEM) was employed to confirm the size and shape of the in situ formed nanoparticles; the result showed that they are spherical in shape and the average size was 28.7 nm with a standard deviation of 11.7 nm. Electron dispersive X-ray spectroscopy (EDS) confirmed the observed nanoparticles are alumina nanoparticles. A scanning electron microscope (SEM) was employed to study microstructural changes in the salt. A differential scanning calorimeter (DSC) was employed to study the heat capacity of the in situ synthesized nanofluid. The result showed that the heat capacity was enhanced by 21% at 550 °C in comparison with pure carbonate salt eutectic. About 10–11 °C decrease of the onset melting point of the binary carbonate salt eutectic was observed for the in situ synthesized nanofluids.
21
Zhang, Tiefeng, Chunfeng Wang, Yongliang Wang, Lijun Qian, and Zhidong Han. "Enhanced Flame Retardancy in Ethylene–Vinyl Acetate Copolymer/Magnesium Hydroxide/Polycarbosilane Blends." Polymers 14, no. 1 (2021): 36. http://dx.doi.org/10.3390/polym14010036.
Full textAbstract:
A polymer ceramic precursor material—polycarbosilane (PCS)—was used as a synergistic additive with magnesium hydroxide (MH) in flame-retardant ethylene–vinyl acetate copolymer (EVA) composites via the melt-blending method. The flame-retardant properties of EVA/MH/PCS were evaluated by the limiting oxygen index (LOI) and a cone calorimeter (CONE). The results revealed a dramatic synergistic effect between PCS and MH, showing a 114% increase in the LOI value and a 46% decrease in the peak heat release rate (pHRR) with the addition of 2 wt.% PCS to the EVA/MH composite. Further study of the residual char by scanning electron microscopy (SEM) proved that a cohesive and compact char formed due to the ceramization of PCS and close packing of spherical magnesium oxide particles. Thermogravimetric analysis coupled with Fourier-transform infrared spectrometry (TG–FTIR) and pyrolysis–gas chromatography coupled with mass spectrometry (Py–GC/MS) were applied to investigate the flame-retardant mechanism of EVA/MH/PCS. The synergistic effect between PCS and MH exerted an impact on the thermal degradation products of EVA/MH/PCS, and acetic products were inhibited in the gas phase.
22
Anandan, Shanmuga Sundaram, Jagannathan Sundarababu, Rajesh Ravi, and Kanchana Venkatesan. "Characteristic study of modified nano CuO powder-based paraffin composite and its experimental investigation of melting/solidification behavior for mobilized cold thermal storage systems." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 236, no. 8 (2021): 4367–83. http://dx.doi.org/10.1177/09544062211047354.
Full textAbstract:
The low thermal conductivity of Phase Change Materials (PCM) reduces its performance and remains a challenging issue. In the present study, modified nano copper oxide powder (CuO) with various weight percentages is dispersed into paraffin wax to form Nano-PCM composites (NPCM). Transmission Electron Microscopy analysis showed the uniform dispersion of modified CuO and spherical in structure. Diffraction Scanning Calorimeter analysis (DSC) showed a trivial difference in the melting point of PCM and NPCM. The peak melting temperature of PCM was 18.56°C and for NPCM with 1% concentration was 17.14°C. The thermal conductivity of NPCM in solid and liquid states was high when compared to that of pure PCM. The thermal conductivity of NPCM with a 1% concentration is enhanced by 52% in a solid state and 20% in a liquid state. Solidification/Melting experiments conducted at different bath temperatures such as 15°C, 17°C, and 19°C for PCM and NPCM revealed that the solidification period and melting period reduced with an increase in concentrations of modified Nano CuO due to augmented heat transfer rates. The solidification time for NPCM with 1% concentration is reduced by 18.33% for discharging temperature 25°C, and melting time are reduced by 16.6% for charging temperature.
23
Nguyen Trong, Hoanh Phong, Xuan Cuong Le, Duy Hang Nguyen, et al. "Preperation of nanochitosan from radiation degraded oligochitosan for shelf life extension of strawberry." Nuclear Science and Technology 7, no. 3 (2021): 34–41. http://dx.doi.org/10.53747/jnst.v7i3.102.
Full textAbstract:
Oligochitosans (OCT) were prepared from chitosan (CTS) by gamma irradiationtechnique. The parameters affecting to the chitosan degradation were studied. And then, OCT nanoparticles wereformed using the method of tripolyphosphate (TPP) cross-linking. Effect of concentration and molecular weight of OCT, concentration of TPP on particle size of the formed OCT nanoparticles were also studied. The formation of OCT nanoparticles was verified by Fourier transform infrared (FT-IR) spectrometer and differential scanning calorimeter (DSC), the morphology was observed using scanning electron microscope (SEM), and the characteristics (particle size and zeta potential) of OCT nanoparticles were also studied. The effect of OCT nanoparticles on strawberry presevation was carried out using the coating method. Results showed that an increase in radiation dose resulted in a decrease of chitosan molecular weight. The OCT with molecular weight of approximately 7.7 kDa was obtained by the synergistic effect of hydrogen peroxide (5 %, v/v) and gamma ray at dose of 30 kGy. The smaller OCT nanoparticles was obtained with a lower molecular weight of OCT. The results of FTIR, DSC indicated the success in the formation of OCT nanoparticles with the particle size approximately 129.9 nm, with the spherical shape. The application of OCT nanoparticles on strawberry has prolonged the preservation times approximately 2.5 times higher comp
24
Mishra, Amit, Parameswara Rao Vuddanda, and Sanjay Singh. "Intestinal Lymphatic Delivery of Praziquantel by Solid Lipid Nanoparticles: Formulation Design,In VitroandIn VivoStudies." Journal of Nanotechnology 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/351693.
Full textAbstract:
The aim of the present work was to design and develop Praziquantal (PZQ) loaded solid lipid nanoparticles (PZQ-SLN) to improve the oral bioavailability by targeting intestinal lymphatic system. PZQ is practically insoluble in water and exhibits extensive hepatic first-pass metabolism. PZQ SLN were composed of triglycerides, lecithin and various aqueous surfactants; were optimized using hot homogenization followed by ultrasonication method. The optimized SLN had particle size of123±3.41 nm, EE of86.6±5.72%. The drug release of PZQ-SLN showed initial burst release followed by the sustained release. Inspite of zeta potential being around −10 mV, the optimized SLN were stable at storage conditions (5±3°C and25±2°C/60±5% RH) for six months. TEM study confirmed the almost spherical shape similar to the control formulations. Solid state characterization using differential scanning calorimeter (DSC) and powder X-ray diffraction (PXRD) analysis confirmed the homogeneous distribution of PZQ within the lipid matrix. The 5.81-fold increase inAUC0→∞, after intraduodenal administration of PZQ-SLN in rats treated with saline in comparison to rats treated with cycloheximide (a blocker of intestinal lymphatic pathway), confirmed its intestinal lymphatic delivery. The experimental results indicate that SLN may offer a promising strategy for improving the therapeutic efficacy and reducing the dose.
25
Hoeft, M., G. Yepes, and S. Gottlöber. "Too Small to Form a Galaxy: How the UV Background Determines the Baryon Fraction." Proceedings of the International Astronomical Union 3, S244 (2007): 279–83. http://dx.doi.org/10.1017/s1743921307014093.
Full textAbstract:
AbstractThe cosmic ultraviolet background (UVB) heats the intergalactic medium (IGM), as a result the gas in dark matter halos below a certain mass is too hot to cool within a Hubble time. The UVB effectively suppresses the formation of dwarf galaxies. Using high resolution cosmological hydrodynamical simulations we show that photo heating leads to small baryon fractions in halos below ~ 6× 109h−1M⊙, independent of the cosmic environment. The simulations are carried out assuming a homogeneous UVB with flux densities as given by Haardt, &, Madau (1996). A halo may stop to condense gas significantly after the universe is reionised, namely when its mass falls below the characteristic mass scale set by the photo heating. Assuming a spherical halo model we derive this characteristic mass analytically and identify the main mechanisms that prevent the gas from cooling in small halos. The theoretically derived characteristic mass is smaller than the one obtained from observations. Increasing the energy per ionising photon by a factor between four and eight would be sufficient to reconcile both. This is equivalent to an average temperature of the IGM of ~ 104K. In this sense the faint end of the luminosity function may serve as a calorimeter for the IGM.
26
Kumar, Girish, Tarun Virmani, Kamla Pathak, Omkulthom Al Kamaly, and Asmaa Saleh. "Central Composite Design Implemented Azilsartan Medoxomil Loaded Nanoemulsion to Improve Its Aqueous Solubility and Intestinal Permeability: In Vitro and Ex Vivo Evaluation." Pharmaceuticals 15, no. 11 (2022): 1343. http://dx.doi.org/10.3390/ph15111343.
Full textAbstract:
The present research attempted to design and develop a nanoemulsion formulation of azilsartan medoxomil to improve its aqueous solubility and intestinal permeability. Based on the solubility profile, ethyl oleate, tween 80, and Transcutol P were selected as the oil phase, surfactant, and co-surfactant, respectively. Central composite design (CCD) suggested an optimized azilsartan medoxomil- nanoemulsion formulation (optimized AZL-NE formulation) with 1.25% oil, 15.73% Smix, and 90 s ultrasonication time; it was found to have the droplet size, percentage transmittance, and % cumulative drug release (%CDR) of 71.5 nm, 93.46 ± 1.13%, and 90.14 ± 0.94%, respectively. Furthermore, it exhibited a 0.141 polydispersity index, 34.05 mV zeta potential, a 1.413 ± 0.03 refractive index, 6.68 ± 0.22 pH, 28.17 ± 0.52 cps viscosity, and a 96.98 ± 0.94% percentage drug content. Transmission electron microscopy (TEM) assessed the nano-sized spherical shape, and a differential scanning calorimeter (DSC) assessed the solubilization of the drug in the optimized formulation. The %CDR was 1.71 times higher and the % cumulative drug permeation was 2.1 times higher for the optimized AZL-NE formulation than for the drug suspension through an intestinal segment of a rat, which was also supported by confocal laser scanning microscopy (CLSM) studies. Thus, the nanoemulsion formulation of azilsartan medoxomil ensured the enhancement of the drug availability in the body.
27
Kamari, Azlan, and Siti Najiah Mohd Yusoff. "N-octyl chitosan derivatives as amphiphilic carrier agents for herbicide formulations." Open Chemistry 17, no. 1 (2019): 365–80. http://dx.doi.org/10.1515/chem-2019-0043.
Full textAbstract:
AbstractThis study investigates the potential of N-octyl chitosan derivatives, namely N-octyl-O-sulfate chitosan (NOOSC), N-octyl-N-succinyl chitosan (NONSC) and N-octyl-O-glycol chitosan (NOOGC) as amphiphilic carrier agents for atrazine in water-insoluble herbicide formulations. The N-octyl chitosan derivatives were characterised using several analytical instruments such as Fourier Transform Infrared (FTIR) Spectrometer, CHNS-O Elemental Analyser (CHNS-O), Transmission Electron Microscope (TEM), Thermogravimetric Analyser (TGA), Differential Scanning Calorimeter (DSC) and Fluorescence Spectrometer. The encapsulation of atrazine by N-octyl chitosan derivatives was studied using a High Performance Liquid Chromatography (HPLC). The FTIR spectra of N-octyl chitosan derivatives confirmed the presence of hydrophobic and hydrophilic groups on chitosan backbone. TEM images revealed that N-octyl chitosan derivatives have formed self-aggregates with a spherical shape. The CMC values for N-octyl chitosan derivatives were between 0.06 and 0.09 mg/mL. The encapsulation efficiency (EE) values for amphiphilic chitosan were greater than 90%. The release profiles showed different release behaviour of pure herbicide in solution as compared to atrazine-loaded N-octyl chitosan derivatives. Results suggest that the chitosan derivatives offer promising characteristics that enable them to act as effective carrier agents for atrazine. In conclusion, the application of N-octyl chitosan derivatives could reduce the use of organic solvents in herbicide formulations by 37.5%.
28
Betti, Pietro, Oscar Adriani, Matias Antonelli, et al. "Double Photodiode Readout System for the Calorimeter of the HERD Experiment: Challenges and New Horizons in Technology for the Direct Detection of High-Energy Cosmic Rays." Instruments 8, no. 1 (2024): 5. http://dx.doi.org/10.3390/instruments8010005.
Full textAbstract:
The HERD experiment is a future experiment for the direct detection of high-energy cosmic rays and is to be installed on the Chinese space station in 2027. The main objectives of HERD are the first direct measurement of the knee of the cosmic ray spectrum, the extension of electron+positron flux measurement up to tens of TeV, gamma ray astronomy, and the search for indirect signals of dark matter. The main component of the HERD detector is an innovative calorimeter composed of about 7500 LYSO scintillating crystals assembled in a spherical shape. Two independent readout systems of the LYSO scintillation light will be installed on each crystal: the wavelength-shifting fibers system developed by IHEP and the double photodiode readout system developed by INFN and CIEMAT. In order to measure protons in the cosmic ray knee region, we must be able to measure energy release of about 250 TeV in a single crystal. In addition, in order to calibrate the system, we need to measure typical releases of minimum ionizing particles that are about 30 MeV. Thus, the readout systems should have a dynamic range of about 107. In this article, we analyze the development and the performance of the double photodiode readout system. In particular, we show the performance of a prototype readout by the double photodiode system for electromagnetic showers as measured during a beam test carried out at the CERN SPS in October 2021 with high-energy electron beams.
29
Umeyor, Chukwuebuka, Uchechukwu Nnadozie, and Anthony Attama. "Development, in vitro and in vivo Evaluations of Solid-Lipid Microparticles based on Solidified Micellar Carrier System for Oral Delivery of Cefepime." International Journal of Pharmaceutical Sciences and Nanotechnology 10, no. 1 (2017): 3582–93. http://dx.doi.org/10.37285/ijpsn.2017.10.1.3.
Full textAbstract:
This study seeks to formulate and evaluate a solid lipid nanoparticle-based, solidified micellar carrier system for oral delivery of cefepime. Cefepime has enjoyed a lot of therapeutic usage in the treatment of susceptible bacterial infections; however, its use is limited due to its administration as an injection only with poor patient compliance. Since oral drug administration encourage high patient compliance with resultant effect in improved therapy, cefepime was formulated as solid lipid microparticles for oral delivery using the concept of solidified micellar carrier system. The carrier system was evaluated based on particle yield, particle size and morphology, encapsulation efficiency (EE %), and thermal analysis using differential scanning calorimeter (DSC). Preliminary microbiological studies were done using gram positive and negative bacteria. In vitro release study was performed using biorelevant media, while in vivo release study was performed in white albino rats. The yield of solid lipid microparticles (SLM) ranged from 84.2 – 98.0 %. The SLM were spherical with size ranges of 3.8 ± 1.2 to 42.0 ± 1.4 µm. The EE % calculated ranged from 83.6 – 94.8 %. Thermal analysis showed that SLM was less crystalline with high potential for drug entrapment. Microbial studies showed that cefepime retained its broad spectrum anti-bacterial activity. In vitro release showed sustained release of cefepime from SLM, and in vivo release study showed high concentration of cefepime released in the plasma of study rats. The study showed that smart engineering of solidified micellar carrier system could be used to improve oral delivery of cefepime.
30
Zhang, Shengchang, Yuan Chen, Christine Campagne, and Fabien Salaün. "Influence of a Coaxial Electrospraying System on the n-Hexadecane/Polycaprolactone Phase Change Microcapsules Properties." Materials 13, no. 9 (2020): 2205. http://dx.doi.org/10.3390/ma13092205.
Full textAbstract:
Electrospraying is considered to be a green, high-efficiency method for synthesizing phase change microcapsules (mPCMs) for possible applications in the fields of energy storage and thermal regulation. In this study, a coaxial nozzle was used to prepare n-hexadecane/polycaprolactone (PCL) microparticles. The objectives of this study were to investigate the influence of working parameters and solutions on morphology, particle size, thermal properties and encapsulation efficiency. Thus, three theoretical loading contents in n-hexadecane (30%, 50% and 70% w/w) and two concentrations of PCL (5 and 10% w/v) were used. The structures, morphologies and thermal properties of mPCMs were characterized by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). Spherical microcapsules with a mean diameter of 10–20 µm were prepared. The increased concentration of n-hexadecane and PCL resulted in a change in the particle size distribution from a poly-disperse to monodisperse size distribution and in a change in the surface state from porous to non-porous. In addition, higher encapsulation efficiency (96%) and loading content (67%) were achieved by the coaxial nozzle using the high core-shell ratio (70/30) and 10% w/v of PCL. The latent heat of the mPCMs reached about 134 J.g−1. In addition, it was also observed that the thermal stability was improved by using a coaxial system rather than a single nozzle.
31
Zhang, Shengchang, Christine Campagne, and Fabien Salaün. "Preparation of n-Alkane/Polycaprolactone Phase-Change Microcapsules via Single Nozzle Electro-Spraying: Characterization on Their Formation, Structures and Properties." Applied Sciences 10, no. 2 (2020): 561. http://dx.doi.org/10.3390/app10020561.
Full textAbstract:
The phase change microcapsule (mPCM) is one of the primary candidates in the fields of energy storage and thermal regulation. In this study, electro-spraying, as a green, high-efficiency electrohydrodynamic atomization technology, is applied to the microencapsulation of two phase change materials (PCM) (n-hexadecane and n-eicosane) with three loading contents (30%, 50%, and 70% by weight) in a polycaprolactone matrix. Ethyl acetate (EA) and chloroform (Chl) were chosen as solvents to prepare the working solutions. The objective of this study is to clarify the microencapsulation process during electro-spraying and to optimize the structure and properties of the electro-sprayed mPCM. The structures, morphologies, and thermal properties of the mPCM were characterized by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and fourier transform infrared spectroscopy (FT-IR). Electro-sprayed spherical and non-porous mPCM have been successfully prepared. The mean diameter and the particle size distribution depend mainly on the choice of the n-alkane, as well as the solvent used to prepare the working solutions. Meanwhile, the structure formation of electro-sprayed mPCM and the loading content of PCM were mainly influenced by the evaporation of the solvent and the phase separation between PCM and poly(caprolactone) (PCL) matrix. During the shell formation or PCL solidification, the control of the PCM leaching out of the matrix allows improving the loading content. Finally, based on a high latent heat and simple formation process, the electro-spraying route of PCM is a green, non-toxic, and high-efficiency direction for energy storage and heat regulation.
32
Dudhipala, Narendar, and Thirupathi Gorre. "Neuroprotective Effect of Ropinirole Lipid Nanoparticles Enriched Hydrogel for Parkinson’s Disease: In Vitro, Ex Vivo, Pharmacokinetic and Pharmacodynamic Evaluation." Pharmaceutics 12, no. 5 (2020): 448. http://dx.doi.org/10.3390/pharmaceutics12050448.
Full textAbstract:
Parkinson’s disease (rp) is a progressive neurodegenerative disorder. Ropinirole (RP) is a newer generation dopamine agonist used for the treatment of PD. It is prescribed as oral dosage form. However, limited oral bioavailability and frequent dosing limits the RP usage. The objective of the current investigation was to develop, optimize, evaluate pharmacokinetic (PK) and pharmacodynamic (PCD) activity of RP loaded solid lipid nanoparticles (RP-SLNs) and nanostructured lipid carriers (RP-NLCs) and containing hydrogel (RP-SLN-C and RP-NLC-C) formulations for improved oral and topical delivery. RP loaded lipid nanoparticles were optimized and converted to hydrogel using carbopol 934 as the gelling polymer. PK and PCD studies in haloperidol-induced PD were conducted in male Wistar rats. In vitro and ex vivo permeation studies showed sustained release profile and enhanced permeation compared with control formulations. Differential scanning calorimeter and X-ray diffraction studies revealed amorphous transformation; scanning electron microscope showed the spherical shape of RP in lipid nanoparticles. PK studies showed 2.1 and 2.7-folds enhancement from RP-SLN and RP-NLC from oral administration, 3.0 and 3.3-folds enhancement from RP-SLN-C and RP-NLC-C topical administration, compared with control formulations, respectively. RP-SLN-C and RP-NLC-C showed 1.4 and 1.2-folds topical bioavailability enhancement compared with RP-SLN and RP-NLC oral administration, respectively. PCD studies showed enhanced dopamine, glutathione, catalase levels and reduced lipid peroxidation levels, compared with the haloperidol-induced PD model. Overall, the results demonstrated that lipid nanoparticles and corresponding hydrogel formulations can be considered as an alternative delivery approach for the improved oral and topical delivery of RP for the effective treatment of PD.
33
Wang, Jun, Feng-Mei Lv, Dong-Li Wang, et al. "Synergistic Antitumor Effects on Drug-Resistant Breast Cancer of Paclitaxel/Lapatinib Composite Nanocrystals." Molecules 25, no. 3 (2020): 604. http://dx.doi.org/10.3390/molecules25030604.
Full textAbstract:
Drug resistance presents serious difficulties for cancer treatment. A combination of paclitaxel (PTX) and lapatinib (LAPA) shows potentials in multiple drug resistant cancers in the clinic, but it is almost impossible to deliver these two drugs to the tumor at the same time with the best proportion by simple co-administration of the respective current formualtions for their different pharmacokinetic profiles. Here composite nanocrystals of PTX and LAPA (cNC) were designed with a ratio of 2:1 (w/w), which was their intracellular ratio at the best synergistic efficacy on a drug-resistant cancer cell line (MCF-7/ADR). Such cNC were prepared using a bottom-up method to achieve a nearly spherical appearance and a narrow size distribution of 95.1 ± 2.1 nm. For nanocrystal stabilization, Polyethylene glycol (PEG) coating was introduced into the cNC via polydopamine (PDA) coating in order to get a PEGylated composite nanocrystal (cNC@PDA-PEG) with nanoscale size (170.5 ± 1.4 nm), considerable drug loading (PTX: 21.33 ± 1.48%, LAPA: 10.95 ± 1.24%) and good stability for at least 4 days in plasma-containing buffers. Differential scanning calorimeter (DSC) and XRD data both indicated the different crystalline states of the cNC as well as the cNC@PDA-PEG in comparison with bulk drugs. In vitro release data showed that PTX and LAPA were gradually and completely released from cNC@PDA-PEG in 3 days, while drug release from bulk drugs or cNC was only 30%. cNC@PDA-PEG also showed negligible hemolysis in vitro. Cellular uptake experiments in the MCF-7/ADR cell line showed that the nanocrystals entered the cells in a complete form through endocytosis and then released the drug in the cell. cNC@PDA-PEG inhibits the growth of this drug-resistant cell more effectively than the unmodified version (cNC). In summary, PEGylated PTX and LAPA composite nanocrystals showed the potential for treament of drug-resistant tumors by simultaneously delivering two drugs to tumor cells with the best proportion.
34
Altun-Anayurt, Ruhan, Sennur Alay-Aksoy, Cemil Alkan, Sena Demirbag, and M. Selda Tözüm. "Development of thermo-regulating fabrics using PCM microcapsules with poly(methyl methacrylate-co-2-hydroxy ethyl methacrylate) shell and n-alkane core." International Journal of Clothing Science and Technology 31, no. 1 (2019): 65–79. http://dx.doi.org/10.1108/ijcst-09-2017-0145.
Full textAbstract:
Purpose The purpose of this paper is to prepare microencapsulated phase change materials (PCMs) and apply them to cotton and wool fabrics for developing thermo-regulating fabrics. Design/methodology/approach Microencapsulated n-hexadecane and n-octadecane with poly(methylmethacrylate-co-2-hydroxy ethyl methacrylate) shell was prepared. Microcapsules were fabricated using oil-in-water emulsion polymerization method. Their chemical structure, microstructure, thermal energy storage properties and thermal stability were analyzed by Fourier-transform infrared spectroscopy, polarized light microscope, differential scanning calorimeter and thermogravimetric analyzer, respectively. The mean particle size was tested by a particle sized instrument. The microcapsules were applied to the wool and cotton fabrics using pad-dry-cure method. The thermo-regulating property of the fabrics was evaluated using the T-History test. The distribution and durability of the microcapsules on the fabrics was investigated with scanning electron microscopy. Findings Spherical microcapsules with p(MMA-co-HEMA) shell and n-alkane core have been produced successfully. n-hexadecane in microcapsule solidifies at 14.8−15.6°C with the latent heat of 65.6−129.8 J/g and melts at 16.7−16.9°C with the latent heat of 67.6−136.9 J/g. Microencapsulated n-octadecane solidifies at 25.8−26.3°C with the latent heat of 74.1−106.2 J/g and melts at 26.8−27.4°C with the latent heat of 80.3−113.4 J/g. The microcapsules have enough thermal stability to the temperature of 150°C that was applied during the fixation of microcapsules on the fabric. The thermo-regulating effect of the microcapsule-incorporated fabrics has been proved by the T-history test. Originality/value PCM microcapsules with p(MMA-co-HEMA) shell and n-hexadecane and n-octadecane core have been produced and their usage to produce thermo-regulating textiles have been proved. To determine the thermo-regulating property of the fabrics treated with these new PCM microcapsules, a T-History system has been designed.
35
Akcicek, Alican, Fatih Bozkurt, Cansu Akgül, and Salih Karasu. "Encapsulation of Olive Pomace Extract in Rocket Seed Gum and Chia Seed Gum Nanoparticles: Characterization, Antioxidant Activity and Oxidative Stability." Foods 10, no. 8 (2021): 1735. http://dx.doi.org/10.3390/foods10081735.
Full textAbstract:
The aim of this study was to determine the potential use of rocket seed and chia seed gum as wall materials, to encapsulate and to prevent degradation of olive pomace extract (OPE) in polymeric nanoparticles, and to characterize olive pomace extract-loaded rocket seed gum nanoparticles (RSGNPs) and chia seed gum nanoparticles (CSGNPs). The phenolic profile of olive pomace extract and physicochemical properties of olive pomace, rocket seed gum (RSG), and chia seed gum (CSG) were determined. The characterization of the nanoparticles was performed using particle size and zeta potential measurement, differential scanning calorimeter (DSC), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), encapsulation efficiency (EE%), in vitro release, and antioxidant activity analyses. Nanoparticles were used to form oil in water Pickering emulsions and were evaluated by oxitest. The RSGNPs and CSGNPs showed spherical shape in irregular form, had an average size 318 ± 3.11 nm and 490 ± 8.67 nm, and zeta potential values of −22.6 ± 1.23 and −29.9 ± 2.57, 25 respectively. The encapsulation efficiency of the RSGNPs and CSGNPs were found to be 67.01 ± 4.29% and 82.86 ± 4.13%, respectively. The OPE-RSGNP and OPE-CSGNP presented peaks at the 1248 cm−1 and 1350 cm−1 which represented that C-O groups and deformation of OH, respectively, shifted compared to the OPE (1252.53 cm−1 and 1394.69 cm−1). The shift in wave numbers showed interactions of a phenolic compound of OPE within the RSG and CSG, respectively. In vitro release study showed that the encapsulation of OPE in RSGNPs and CSGNPs led to a delay of the OPE released in physiological pH. The total phenolic content and antioxidant capacity of RSGNPs and CSGNPs increased when the OPE-loaded RSGNPs and CSGNPs were formed. The encapsulation of OPE in RSGNPs and CSGNPs and the IP values of the oil in water Pickering emulsions containing OPE-RSGNPs and OPE-CSGNPs were higher than OPE, proving that OPE-loaded RSGNPs and CSGNPs significantly increased oxidative stability of Pickering emulsions. These results suggest that the RSG and CSG could have the potential to be utilized as wall materials for nanoencapsulation and prevent degradation of cold-pressed olive pomace phenolic extract.
36
Mendes, Jessica Bitencourt Emilio, Manoela Klüppel Riekes, Viviane Matoso de Oliveira, et al. "PHBV/PCL Microparticles for Controlled Release of Resveratrol: Physicochemical Characterization, Antioxidant Potential, and Effect on Hemolysis of Human Erythrocytes." Scientific World Journal 2012 (2012): 1–13. http://dx.doi.org/10.1100/2012/542937.
Full textAbstract:
Microparticles of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL) containing resveratrol were successfully prepared by simple emulsion/solvent evaporation. All formulations showed suitable encapsulation efficiency values higher than 80%. PHBV microparticles revealed spherical shape with rough surface and presence of pores. PCL microparticles were spherically shaped with smooth surface. Fourier-transformed infrared spectra demonstrated no chemical bond between resveratrol and polymers. X-ray powder diffraction patterns and differential scanning calorimetry analyses indicated that microencapsulation led to drug amorphization. These PHBV/PCL microparticles delayed the dissolution profile of resveratrol. Release profiles were better fitted to biexponential equation. The hypochlorous-acid-scavenging activity and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation discoloration assay confirmed that the antioxidant activity of PHBV/PCL microparticles was kept, but was dependent on the microparticle morphology and dissolution profile. Resveratrol-loaded PHBV/PCL microparticles showed no cytotoxic effect on red blood cells.
37
Li, Jianwei. "Thermomechanical constitutive equations for glass and numerical simulation on automobile glass forming technology." Glass Technology: European Journal of Glass Science and Technology Part A 63, no. 4 (2022): 122–28. http://dx.doi.org/10.13036/17533546.63.4.006.
Full textAbstract:
To establish a comprehensive numerical model for automotive glass forming, firstly, this paper conducts material tests of 3·2 SG glass to obtain detailed material properties. Through thermal expansion experiments, the thermal expansion coefficients including glassy and liquid states are obtained; then by using three-point bending stress relaxation and differential scanning calorimetry experiments, the stress relaxation and structural relaxation properties of the glass are obtained. Finally, a comparison analysis of the simulation and the actual spherical deviation for an actual automobile glass product is carried out. The result shows that the product simulation and the actual product spherical deviation correspond. The maximum value of the spherical deviation is within 0·94 mm between simulation and the actual product spherical deviation. The accuracy can meet the design requirements, and the established numerical model is reliable.
38
Hou, Zhao Xia, Hang Xin Li, Shao Hong Wang, Mei Han Wang, and Xiao Dan Hu. "Preparation and Characterization of Transparent Oxyfluoride Tellurite Glass-Ceramics Containing CaF2 Nanocrystals." Advanced Materials Research 989-994 (July 2014): 305–7. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.305.
Full textAbstract:
Transparent oxyfluoride tellurite glass-ceramics containing CaF2 nanocrystals were prepared by high temperature melting method. The glass-ceramics were characterized by Differential scanning calorimetry, X-ray diffraction and scanning electron microscope, respectively. The results showed that the CaF2 nanocrystals were spherical and the average size was found to be 60 nm.
39
J, HASIFUL ARABI, SUBRAMANIAN L, and RAJESH M. "A review on spherical crystallization: A novel technique in the field of particle engineering." World Journal of Biology Pharmacy and Health Sciences 13, no. 1 (2023): 078–93. https://doi.org/10.5281/zenodo.7939851.
Full textAbstract:
In the production of tablets, the direct compression method is mostly used. In comparison to the traditional wet granulation approach, this cannot be used with sensitive pharmaceuticals and also has a lot more processing limitations. Spherical agglomeration is a novel method for creating pharmaceutical dosage forms that are immediately compressible, the process of spherical agglomeration, which improves the powder's qualities such as particle size, shape, flow characteristics, solubility, and bioavailability of pharmaceutical medicinal ingredients, includes transforming tiny crystals into a spherical shape. The spherical crystallization was improved for use with hydrophilic polymers in order to improve the dissolution properties of pharmaceuticals that are poorly water-soluble. The flow characteristics, particle size analysis, compression, and dissolution behaviour of the spherical agglomerates were also improved. Wet spherical agglomeration (WSA) and the quasiemulsion solvent diffusion method (QESD) are the two most used methods for crystallizing spheres. Additionally, these approaches have two additions: the ammonia diffusion system (ADS) and crystallo-coagglomeration (CCA).The neutralization technique is another method used in this procedure. Any of the aforementioned methods can be employed simultaneously for both crystallization and agglomeration. The crystal physical characteristics, including their shape, polymorphism detection using x-ray powder diffraction (XRD), and thermodynamic characteristics using differential scanning calorimetry (DSC), were examined.
40
Indra, Indra, Gustania Intan Indriani, and Tuslinah Lilis. "CRYSTALLO-CO-AGGLOMERATION OF SIMVASTATIN: IMPROVING DISSOLUTION AND MICROMERITIC PROPERTIES." Pharmacoscript 7, no. 2 (2024): 196–207. http://dx.doi.org/10.36423/pharmacoscript.v7i2.1679.
Full textAbstract:
Simvastatin (SMV), a poorly soluble drug, faces challenges in pharmaceutical formulation due to its limited solubility and poor flow properties. This study aimed to enhance the physicochemical properties of SMV by preparing spherical crystals using a crystallo-co-agglomeration. Spherical crystals of SMV were prepared by dissolving the drug in methanol and adding it to an aqueous solution containing PVP K-30 and PEG 6000 under constant stirring. The resulting agglomerates were filtered, dried, and characterized using Fourier Transform Infrared (FTIR) spectroscopy, Powder X-Ray Diffraction (PXRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and dissolution testing. Micromeritic properties, including bulk density, Hausner ratio, compressibility index, angle of repose, and flowability, were also evaluated. FTIR confirmed the chemical integrity of SMV with minor shifts indicating interactions with stabilizers. PXRD and DSC analyses revealed reduced crystallinity and partial amorphization in the spherical crystals. SEM showed spherical morphology. Dissolution testing demonstrated a significantly enhanced dissolution rate for the spherical crystals compared to pure SMV. Improved micromeritic properties were also observed, indicating better flowability and packing density. Spherical crystallization significantly improved the solubility, dissolution rate, and flowability of SMV. This technique offers a promising strategy for enhancing the bioavailability and pharmaceutical performance of poorly soluble drugs.
41
J HASIFUL ARABI, L SUBRAMANIAN, and M RAJESH. "A review on spherical crystallization: A novel technique in the field of particle engineering." World Journal of Biology Pharmacy and Health Sciences 13, no. 1 (2023): 078–93. http://dx.doi.org/10.30574/wjbphs.2023.13.1.0281.
Full textAbstract:
In the production of tablets, the direct compression method is mostly used. In comparison to the traditional wet granulation approach, this cannot be used with sensitive pharmaceuticals and also has a lot more processing limitations. Spherical agglomeration is a novel method for creating pharmaceutical dosage forms that are immediately compressible, the process of spherical agglomeration, which improves the powder's qualities such as particle size, shape, flow characteristics, solubility, and bioavailability of pharmaceutical medicinal ingredients, includes transforming tiny crystals into a spherical shape. The spherical crystallization was improved for use with hydrophilic polymers in order to improve the dissolution properties of pharmaceuticals that are poorly water-soluble. The flow characteristics, particle size analysis, compression, and dissolution behaviour of the spherical agglomerates were also improved. Wet spherical agglomeration (WSA) and the quasiemulsion solvent diffusion method (QESD) are the two most used methods for crystallizing spheres. Additionally, these approaches have two additions: the ammonia diffusion system (ADS) and crystallo-coagglomeration (CCA).The neutralization technique is another method used in this procedure. Any of the aforementioned methods can be employed simultaneously for both crystallization and agglomeration. The crystal physical characteristics, including their shape, polymorphism detection using x-ray powder diffraction (XRD), and thermodynamic characteristics using differential scanning calorimetry (DSC), were examined.
42
Mishra, Rakesh Kumar. "SPHERICAL CRYSTALLIZATION A NOVEL APPROACH FOR SOLUBILITY AND DISSOLUTION ENHANCEMENT OF SIMVASTATIN." Asian Journal of Pharmaceutical and Clinical Research 9, no. 6 (2016): 65. http://dx.doi.org/10.22159/ajpcr.2016.v9i6.13420.
Full textAbstract:
Simvastatin is commonly used antihyperlipidemic in the treatment of hypercholesterolemia and dyslipidemia. As evidenced form the scientific investigation, it is reported for its lower solubility and poor dissolution rate. The aim of the present investigation was to develop simvastatin spherical agglomerates to improve its solubility and dissolution characteristics by spherical agglomeration method. The crystallization media used was methanol, water and chloroform as bridging liquid and PVP K-30 as a polymer. The process variables such as amount and type of (bridging liquid and polymer), stirring speed and stirring time were optimized and reported. The spherical agglomerates were further subjected for determination of % drug content, particle size analysis, solubility and dissolution rate. The agglomerates were also characterized by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Powder Diffraction (XRD) analysis and affirmed. Among the entire parameters spherical agglomerates obtained with methanol (7ml), water (50ml), chloroform (1.5ml) and PVP K-30 (0.5%) showed improvement in solubility and dissolution rate in comparison with pure drug. The spherical agglomerates showed significant improvement in dissolution from a value of 25.53% for pure simvastatin to 91.31% of spherical agglomerate. The spherical agglomerates of optimized batch were directly compressed and dissolution profile was compared with marketed tablet. Such a technique can successfully be employed to improve solubility and dissolution characteristic of poorly soluble drugs.
43
Gupta, Venkadari, Srinivas Mutalik, Madhobhai Patel, and Girish Jani. "Spherical crystals of celecoxib to improve solubility, dissolution rate and micromeritic properties." Acta Pharmaceutica 57, no. 2 (2007): 173–84. http://dx.doi.org/10.2478/v10007-007-0014-8.
Full textAbstract:
Spherical crystals of celecoxib to improve solubility, dissolution rate and micromeritic propertiesCelecoxib spherical agglomerates were prepared with polyvinylpyrrolidone (PVP) using acetone, water and chloroform as solvent, non-solvent and bridging liquid, respectively. The agglomerates were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), IR spectroscopic studies and scanning electron microscopy (SEM). The IR spectroscopy and DSC results indicated the absence of any interactions between drug and additives. XRD studies showed a decrease in crystallinity in agglomerates. The crystals exhibited significantly improved micromeritic properties compared to pure drug. The loading efficiency (% or mg drug per 100 mg crystals) was in the range of 93.9 ± 2.3 and 97.3 ± 1.3% (n = 3) with all formulations. The aqueous solubility and dissolution rate of the drug from crystals was significantly (p < 0.05) increased (nearly two times). The solubility andin vitrodrug release rates increased with an increase in PVP concentration (from 2.5 to 10%). The SEM studies showed that the crystal posseses a good spherical shape with smooth and regular surface.
44
Pistone, Alessandro, Annamaria de Gaetano, Elpida Piperopoulos, and Chiara Abate. "Effect of Sodium Hydroxide and Tripolyphosphate on Curcumin Release from Chitosan-Based Macroparticles." Materials 16, no. 17 (2023): 5850. http://dx.doi.org/10.3390/ma16175850.
Full textAbstract:
This work deals with the synthesis of bare and curcumin (CUR)-loaded chitosan (CS)-based macroparticles by ionic gelation using sodium hydroxide (NaOH) or sodium tripolyphosphate (TPP). The resulting spherical-shaped macroparticles were studied using various characterization techniques, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). The release of CUR from the CS-based particles with respect to time was analyzed, and the encapsulation efficiency and degree of swelling were studied. All formulations showed excellent CUR trapping efficiency, exceeding 90%. In particular, the TPP-crosslinked macrobeads released 34 wt% of the charged CUR within minutes, while the remaining 66 wt% was released slowly. The results indicate that the correct choice of gelling agent and its concentration leads to spherical particles capable of encapsulating CUR and releasing it in a wide range of kinetics so that macrospheres can be used in different applications.
45
Mehenni, Lyes, Malika Lahiani-Skiba, Guy Ladam, François Hallouard, and Mohamed Skiba. "Preparation and Characterization of Spherical Amorphous Solid Dispersion with Amphotericin B." Pharmaceutics 10, no. 4 (2018): 235. http://dx.doi.org/10.3390/pharmaceutics10040235.
Full textAbstract:
In the present study, new polymer microspheres of amphotericin B (AmB) were prepared by a spray drying technique using cyclodextrin polymers (Poly-CD) to improve the solubility and dissolution of AmB, to prevent in vivo toxic AmB aggregations. Formulations were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermal analysis, Raman spectroscopy, particle size, drug purity test and in vitro release studies. The analysis indicated that the chemical structure of AmB remained unchanged in the amorphous solid dispersion, but the structure was changed from crystalline to amorphous. AmB was completely release from such optimized formulations in dissolution media in 40 min. This work may contribute to a new generation of spherical amorphous solid dispersion using a cyclodextrin polymer, which has implications for the possibility of drug development for oral utilization or as powder aerosols for pulmonary administration.
46
Masuno, A., H. Inoue, J. Yu, Yasutomo Arai, and Fumiaki Otsubo. "Thermal Stability and Optical Properties of Er3+ Doped BaTi2O5 Glasses." Advanced Materials Research 39-40 (April 2008): 243–46. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.243.
Full textAbstract:
Er3+ doped BaTi2O5 spherical glasses were prepared using a containerless processing with an aerodynamic levitation furnace. These glasses were found to have high solubility of Er3+ and the substitution ratio of Er3+ for Ba2+ reached 30 %. Differential scanning calorimetry measurements revealed that the glass transition temperature Tg and the crystallization onset temperature Tx shifted to high temperatures and the value of T (= Tx – Tg) increased with substitution of Er3+, indicating that the stability against crystallization improved. We found that these glasses had high refractive indices exceeding 2.1 with low Abbe numbers of approximately 20.
47
Saritha, Damineni, Penjuri Subhash Chandra Bose, Poreddy Srikanth Reddy, Grandhi Madhuri, and Ravouru Nagaraju. "Improved dissolution and micromeritic properties of naproxen from spherical agglomerates: preparation, in vitro and in vivo characterization." Brazilian Journal of Pharmaceutical Sciences 48, no. 4 (2012): 667–76. http://dx.doi.org/10.1590/s1984-82502012000400010.
Full textAbstract:
Naproxen, an anti-inflammatory drug, exhibits poor aqueous solubility, which limits the pharmacological effects. The present work was carried out to study the effect of agglomeration on micromeritic properties and dissolution. Naproxen agglomerates were prepared by using a three solvents system composed of acetone (good solvent), water (non-solvent) and dichloromethane (bridging liquid). Differential Scanning Calorimetry (DSC) results showed no change in the drug after crystallization process. X-Ray Powder Diffraction (XRPD) studies showed the sharp peaks are present in the diffractograms of spherical agglomerates with minor reduction in height of the peaks. The residual solvents are largely below the tolerated limits in the agglomerates. Scanning Electronic Microscopy (SEM) studies showed that agglomerates were spherical in structure and formed by cluster of small crystals. The agglomerates exhibited improved solubility, dissolution rate and micromeritic properties compared to pure drug. Anti-inflammatory studies were conducted in Wistar strain male albino rats and naproxen agglomerates showed more significant activity than the pure drug.
48
Wu, Li-Chuan, Yi-Wen Huang, Yao-Ming Yeh, and Chih-Hung Lin. "Characteristic and Synthesis of High-Temperature Resistant Liquid Crystal Epoxy Resin Containing Boron Nitride Composite." Polymers 14, no. 6 (2022): 1252. http://dx.doi.org/10.3390/polym14061252.
Full textAbstract:
Five liquid crystal epoxy resins and composites containing flat boron nitride (f-BN) and spherical boron nitride (s-BN) were successfully synthesized. The chemical structures, crystal diffraction, and thermal conductivity of the liquid crystal (LC) epoxy composites were measured using Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), X-ray, and Discovery Xenon Flash. In this study, the molecular arrangement of five LC epoxy resins and the thermal conductivity of their composites were carefully discussed. Several different amounts of flat boron nitride and spherical boron nitride were added to the five LC epoxy resins. The influence of nano-scale ceramic materials, f-BN, and s-BN, on the thermal conductivity of the LC epoxy resins, was studied. It is worth noting that the thermal conductivity of the spherical boron nitride composite demonstrated a better result than that of the flat boron nitride composite. In simpler terms, the thermal conductivity of the composites is closely related to the molecular arrangement of the LC resin and the amount of BN added. The results demonstrate that the SBPDAE/s-BN (60%) composite shows the highest thermal conductivity of 9.36 W/mK in the vertical direction. These data prove that the LC alignment of the matrix will greatly enhance the thermal conductivity of the composites.
49
Sonnenberg, Heike, and Brigitte Clausen. "Short-Term Characterization of Spherical 100Cr6 Steel Samples Using Micro Compression Test." Materials 13, no. 3 (2020): 733. http://dx.doi.org/10.3390/ma13030733.
Full textAbstract:
For the establishment of a novel development process of new structural materials, short-term characterization methods capable of testing hundreds of spherical micro samples are needed. This paper introduces a compression test on spherical micro samples as a short-term characterization method to investigate the elastic-plastic deformation behavior. To demonstrate the potential of this newly developed method, the micro compression test is performed with a maximum loading of 300 N on 100Cr6 (AISI 52100 bearing steel) samples, with a diameter of 0.8 mm, in 15 different heat treatment conditions. The austenitizing temperature is varied between 800 and 1150 °C. Tempering of the samples is carried out in a differential scanning calorimetry process with temperatures of 180, 230 and 300 °C. Out of force-displacement curves and stress-strain relations, so-called descriptors (characteristic values) which are sensitive to the applied heat treatment can be extracted. The change of mechanical properties due to heat treatment and the resulting microstructure is presented by the trend of a stress descriptor in dependence of austenitizing and annealing temperature, which can be compared to the trend of the tensile strength as a material property obtained by conventional tensile tests. The trend of the descriptor determined in the compression test on spherical samples indicates the validity of this approach as a short-term characterization method.
50
Toenjes, Anastasiya, Heike Sonnenberg, Christina Plump, Rolf Drechsler, and Axel von Hehl. "Measurement and Evaluation of Calorimetric Descriptors for the Suitability for Evolutionary High-Throughput Material Development." Metals 9, no. 2 (2019): 149. http://dx.doi.org/10.3390/met9020149.
Full textAbstract:
A novel method for evolutionary material development by using high-throughput processing is established. For the purpose of this high-throughput approach, spherical micro samples are used, which have to be characterized, up-scaled to macro level and valued. For the evaluation of the microstructural state of the micro samples and the associated micro-properties, fast characterization methods based on physical testing methods such as calorimetry and universal microhardness measurements are developed. Those measurements result in so-called descriptors. The increase in throughput during calorimetric characterization using differential scanning calorimetry is achieved by accelerating the heating rate. Consequently, descriptors are basically measured in a non-equilibrium state. The maximum heating rate is limited by the possibility to infer the microstructural state from the calorimetric results. The substantial quality of the measured descriptors for micro samples has to be quantified and analyzed depending on the heating rate. In this work, the first results of the measurements of calorimetric descriptors with increased heating rates for 100Cr6 will be presented and discussed. The results of low and high heating rates will be compared and analyzed using additional microhardness measurements. Furthermore, the validation of the method regarding the suitability for the evolutionary material development includes up-scaling to macro level and therefore different sample masses will be investigated using micro and macro samples during calorimetry.