This work is a simulation modelling with the LAMMPS calculation code of an electrode based on alkali metals (lithium, sodium and potassium) using the MEAM potential. For different multiplicities, two models were studi...This work is a simulation modelling with the LAMMPS calculation code of an electrode based on alkali metals (lithium, sodium and potassium) using the MEAM potential. For different multiplicities, two models were studied;with and without gap. In this work, we present the structural, physical and chemical properties of the lithium, sodium and potassium electrodes. For the structural properties, the cohesive energy and the mesh parameters were calculated, revealing that, whatever the chemical element selected, the compact hexagonal hcp structure is the most stable, followed by the face-centred cubic CFC structure, and finally the BCC structure. The most stable structure is lithium, with a cohesion energy of -6570 eV, and the lowest bcc-hcp transition energy of -0.553 eV/atom, followed by sodium. For physical properties, kinetic and potential energies were calculated for each of the sectioned chemical elements, with lithium achieving the highest value. Finally, for the chemical properties, we studied the diffusion coefficient and the activation energy. Only potassium followed an opposite order to the other two, with the quantities with lacunae being greater than those without lacunae, whatever the multiplicity. The order of magnitude of the diffusion coefficients is given by the relationship D<sub>Li</sub> > D<sub>Na</sub> > D<sub>k</sub> for the multiplicity 6*6*6, while for the activation energy the order is reversed.展开更多
In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallograph...In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallographic structures (HCP, FCC, BCC and SC) using the Modified Embedded Atom Method (MEAM) and the MEAM potential of titanium. We used the LAMMPS calculation code, based on classical molecular dynamics, to determine the most stable structure of titanium, which is the hexagonal compact structure (HCP) with crystal parameters a = 2.952 Å and c = 4.821 Å and a cohesion energy of -4.87 eV. This structure is seconded by the cubic centred structure (BCC) with a lattice parameter a = 3.274 Å and a cohesive energy of -4.84 eV. It was shown that titanium can crystallise into a third structure which is the face-centred cubic (FCC) structure with a lattice parameter a = 4.143 Å and a cohesive energy of -4.82 eV. The results obtained in this study were compared with the theoretical results and showed considerable agreement.展开更多
Objective To develop a highly sensitive and rapid nucleic acid detection method for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Methods We designed,developed,and manufactured an integrated disposab...Objective To develop a highly sensitive and rapid nucleic acid detection method for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Methods We designed,developed,and manufactured an integrated disposable device for SARS-CoV-2 nucleic acid extraction and detection.The precision of the liquid transfer and temperature control was tested.A comparison between our device and a commercial kit for SARS-Cov-2 nucleic acid extraction was performed using real-time fluorescence reverse transcription polymerase chain reaction(RT-PCR).The entire process,from SARS-CoV-2 nucleic acid extraction to amplification,was evaluated.Results The precision of the syringe transfer volume was 19.2±1.9μL(set value was 20),32.2±1.6(set value was 30),and 57.2±3.5(set value was 60).Temperature control in the amplification tube was measured at 60.0±0.0℃(set value was 60)and 95.1±0.2℃(set value was 95)respectively.SARS-Cov-2 nucleic acid extraction yield through the device was 7.10×10^(6) copies/mL,while a commercial kit yielded 2.98×10^(6) copies/mL.The mean time to complete the entire assay,from SARS-CoV-2 nucleic acid extraction to amplification detection,was 36 min and 45 s.The detection limit for SARS-CoV-2 nucleic acid was 250 copies/mL.Conclusion The integrated disposable devices may be used for SARS-CoV-2 Point-of-Care test(POCT).展开更多
The conductivity and stability of Na-beta alumina are markedly affected by H2O. This is a problem of both theoretical and practical interest and has been studied recently by various authors （see e.g. Refs. [1—3] and...The conductivity and stability of Na-beta alumina are markedly affected by H2O. This is a problem of both theoretical and practical interest and has been studied recently by various authors （see e.g. Refs. [1—3] and the works cited therein）. As for the influence of H2O on the conductivity of Na-beta almina （hereafter referred to as beta alumina except in case special reference to Na-ion is necessary）, it was usually measured with mono-or poly-crystalline beta alumina in plate form with few authors using directly beta alumina tubes in contact with moist air. In a previous paper we展开更多
To clarify the contribution of left atrial pressure to the secretion of beta-endorphin, we have investigated the relation between plasma beta endorphin levels and hemodynamic changes in 35 patients with mitral stenosi...To clarify the contribution of left atrial pressure to the secretion of beta-endorphin, we have investigated the relation between plasma beta endorphin levels and hemodynamic changes in 35 patients with mitral stenosis undergoing percutaneous transvenous mitral commissurotomy (PTMC). Before PTMC, plasma beta-endorphin levels obtained from the antecubital vein (28.91 ± 5.59 pg / ml) and from the femoral vein (28.20 ± 5.44 pg / ml) in the patients with mitral stenosis were significantly higher than those obtained from the antecubital vein in the healthy volunteers (22.59 ± 3.86 pg / ml, n = 34, P< 0.001 for each). The levels of beta-endorphin in the femoral vein correlated well with the mean left atrial pressure (r=0.777, P< 0.001) and the mean right atrial pressure (r = 0.450, P<0.01) before the procedure. The antecubital venous levels of beta-endorphin in patients in New York Heart Association functional Classess Ⅱ (26.45 ± 5.39 pg / ml, n = 20) and Ⅲ (32.20 ± 4.02 pg / ml, n = 15) were significantly higher than those in control subjects (P< 0.005 and P< 0.001, respectively). The differences between Classes Ⅱ and Ⅲ were significant (P < 0.001). The plasma levels of beta-endorphin in the patients complicated with atrial fibrillation were also significantly higher than those in patients with normal sinus rhythm (33.31 ± 3.22 pg / ml, n= 13 vs 26.32± 5.07 pg / ml, n = 22, P< 0.001). In ten to fifteen minutes after commissurotomy, plasma levels of beta-endorphin in the femoral vein significantly increased from 28.20 ± 5.44 to 33.14 ± 5.72 pg / ml (P< 0.001). In seventy-two hours after the procedure, plasma beta-endorphin levels in the antecubital vein fell to 24.37 ± 2.59 pg / ml (P< 0.001 vs before PTMC and P<0.05 vs control subjects). Plasma beta-endorphin levels in the patients with atrial fibrillation (26.62 ± 2.36 pg / ml, P< 0.001 vs before PTMC and P< 0.002 vs control subjects) were still higher (P< 0.001) than those in patients with normal shins rhythm (23.05 ± 1.65 pg / ml, P< 0.001 vs before PTMC and P>50 vs control subjects. There was a significant correlation between the levels of beta-endorphin in the antecubital vein and heart rate (r = 0.502, P< 0.001), mean transmitral pressure gradient (r = 0.543, P< 0.001) or mitral valve area (r = -0.710, P< 0.001) before and 72 hours after the procedure.展开更多
In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K ...In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K and 1520 K using the Modified Embedded Atom Method MEAM under the calculation code LAMMPS version 2020. This study has enabled us to understand the behavior of the TiN alloy under different nitrogen percentages in terms of total energy, vacancy formation energy, crystalline parameter, occupancy rate and order parameter. For total energy, we have shown that as temperature increases, total energy decreases, making it easier to obtain TiN at higher temperatures;reaching the value of -7344.9169 eV for the 55% nitrogen structure for the temperature of 1420 K. For the energy of formation, we have shown that the compounds obtained at 1320 K and 1520 K have a more considerable energy of formation than that obtained at 1420 K. The study of fractions and the order parameter showed us that the structure of TiN with 55% nitrogen is less likely, as the composition obtained is at most 53.35%.展开更多
The reaction between high purity nickel (99.999%) and high purity tin (99.999%) was investigated in the temperature range of 232℃ - 330℃, at short periods of annealing (1 - 60 s). The reaction kinetic was studied us...The reaction between high purity nickel (99.999%) and high purity tin (99.999%) was investigated in the temperature range of 232℃ - 330℃, at short periods of annealing (1 - 60 s). The reaction kinetic was studied using cross-sectional scanning electron microscope (SEM) images. The intermetallic compound (IMC) growth was analyzed using the empirical power law and a time dependence in the range of 0.26 to 0.33 was found. The morphology of the IMC was investigated by SEM in the temperature range of 235℃ - 290℃, at annealing periods of 10 s, 30 s, and 60 s by selectively etching away the remaining elementary tin. The exposed IMC displays a change in morphology with increasing annealing temperature, demonstrating that the growth velocity of certain crystallographic orientations of the IMC is strongly influenced by the annealing temperature. Additionally, coarsening and crumbling of the IMC grains is observed, and will be discussed with respect to the responsible mechanisms.展开更多
Pedunculate oak and sessile oak are important natural species in the Upper Rhine Valley. The increasing mortality of these oak species has been observed since the 1980s in this region, mainly due to severe droughts. T...Pedunculate oak and sessile oak are important natural species in the Upper Rhine Valley. The increasing mortality of these oak species has been observed since the 1980s in this region, mainly due to severe droughts. Turkey oak is known to be highly productive and drought-resistant. The goal of this article is therefore to investigate the adaptability to drought of these three young oak species growing at the same site, and to show to what extent Turkey oak can be substituted for these native oak species. Stand measurements and retrospective analyses of radial growth were performed within the framework of the eight-year-old “Mooswald” afforestation experiment in order to determine stand volume, mortality and resistance/resilience to drought for each species. Turkey oak shows significantly higher stand volume and significantly lower mortality than sessile oak. Values of these two parameters for Turkey oak and sessile oak are not significantly different from those of pedunculate oak. However, Turkey oak is not more resistant to drought than the other oak species. Sessile oak has the highest mortality and the smallest stand volume, while pedunculate oak is the least resilient to drought. These results are only a trend that must be confirmed in older stand stages and investigation in young stands must continue, supported by better monitoring and improved tools.展开更多
为检测头孢氨苄中杂质的含量,特建立此方法用于测定头孢氨苄中杂质L-头孢氨苄含量。采用HPLC法,色谱条件为采用CAPCELL PAK C18 MG‖色谱柱,将0.1 mol/L磷酸二氢钠(p H值为5.0)为流动相A,甲醇为流动相B,采用梯度洗脱,流速1.5 m L/min在2...为检测头孢氨苄中杂质的含量,特建立此方法用于测定头孢氨苄中杂质L-头孢氨苄含量。采用HPLC法,色谱条件为采用CAPCELL PAK C18 MG‖色谱柱,将0.1 mol/L磷酸二氢钠(p H值为5.0)为流动相A,甲醇为流动相B,采用梯度洗脱,流速1.5 m L/min在220nm波长处测定。经对此方法进行方法验证,头孢氨苄和L-头孢氨苄在此条件下分离度良好,专属性、准确度、重复性、检测限、定量限等均满足要求。经方法学验证结果表明,本法可用于对头孢氨苄原料中L-头孢氨苄的质量控制。展开更多
文摘This work is a simulation modelling with the LAMMPS calculation code of an electrode based on alkali metals (lithium, sodium and potassium) using the MEAM potential. For different multiplicities, two models were studied;with and without gap. In this work, we present the structural, physical and chemical properties of the lithium, sodium and potassium electrodes. For the structural properties, the cohesive energy and the mesh parameters were calculated, revealing that, whatever the chemical element selected, the compact hexagonal hcp structure is the most stable, followed by the face-centred cubic CFC structure, and finally the BCC structure. The most stable structure is lithium, with a cohesion energy of -6570 eV, and the lowest bcc-hcp transition energy of -0.553 eV/atom, followed by sodium. For physical properties, kinetic and potential energies were calculated for each of the sectioned chemical elements, with lithium achieving the highest value. Finally, for the chemical properties, we studied the diffusion coefficient and the activation energy. Only potassium followed an opposite order to the other two, with the quantities with lacunae being greater than those without lacunae, whatever the multiplicity. The order of magnitude of the diffusion coefficients is given by the relationship D<sub>Li</sub> > D<sub>Na</sub> > D<sub>k</sub> for the multiplicity 6*6*6, while for the activation energy the order is reversed.
文摘In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallographic structures (HCP, FCC, BCC and SC) using the Modified Embedded Atom Method (MEAM) and the MEAM potential of titanium. We used the LAMMPS calculation code, based on classical molecular dynamics, to determine the most stable structure of titanium, which is the hexagonal compact structure (HCP) with crystal parameters a = 2.952 Å and c = 4.821 Å and a cohesion energy of -4.87 eV. This structure is seconded by the cubic centred structure (BCC) with a lattice parameter a = 3.274 Å and a cohesive energy of -4.84 eV. It was shown that titanium can crystallise into a third structure which is the face-centred cubic (FCC) structure with a lattice parameter a = 4.143 Å and a cohesive energy of -4.82 eV. The results obtained in this study were compared with the theoretical results and showed considerable agreement.
基金supported by National Key R&D Program of China[2021YFC2301103 and 2022YFE0202600]Shenzhen Science and Technology Program[JSGG20220606142605011].
文摘Objective To develop a highly sensitive and rapid nucleic acid detection method for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Methods We designed,developed,and manufactured an integrated disposable device for SARS-CoV-2 nucleic acid extraction and detection.The precision of the liquid transfer and temperature control was tested.A comparison between our device and a commercial kit for SARS-Cov-2 nucleic acid extraction was performed using real-time fluorescence reverse transcription polymerase chain reaction(RT-PCR).The entire process,from SARS-CoV-2 nucleic acid extraction to amplification,was evaluated.Results The precision of the syringe transfer volume was 19.2±1.9μL(set value was 20),32.2±1.6(set value was 30),and 57.2±3.5(set value was 60).Temperature control in the amplification tube was measured at 60.0±0.0℃(set value was 60)and 95.1±0.2℃(set value was 95)respectively.SARS-Cov-2 nucleic acid extraction yield through the device was 7.10×10^(6) copies/mL,while a commercial kit yielded 2.98×10^(6) copies/mL.The mean time to complete the entire assay,from SARS-CoV-2 nucleic acid extraction to amplification detection,was 36 min and 45 s.The detection limit for SARS-CoV-2 nucleic acid was 250 copies/mL.Conclusion The integrated disposable devices may be used for SARS-CoV-2 Point-of-Care test(POCT).
文摘The conductivity and stability of Na-beta alumina are markedly affected by H2O. This is a problem of both theoretical and practical interest and has been studied recently by various authors （see e.g. Refs. [1—3] and the works cited therein）. As for the influence of H2O on the conductivity of Na-beta almina （hereafter referred to as beta alumina except in case special reference to Na-ion is necessary）, it was usually measured with mono-or poly-crystalline beta alumina in plate form with few authors using directly beta alumina tubes in contact with moist air. In a previous paper we
文摘To clarify the contribution of left atrial pressure to the secretion of beta-endorphin, we have investigated the relation between plasma beta endorphin levels and hemodynamic changes in 35 patients with mitral stenosis undergoing percutaneous transvenous mitral commissurotomy (PTMC). Before PTMC, plasma beta-endorphin levels obtained from the antecubital vein (28.91 ± 5.59 pg / ml) and from the femoral vein (28.20 ± 5.44 pg / ml) in the patients with mitral stenosis were significantly higher than those obtained from the antecubital vein in the healthy volunteers (22.59 ± 3.86 pg / ml, n = 34, P< 0.001 for each). The levels of beta-endorphin in the femoral vein correlated well with the mean left atrial pressure (r=0.777, P< 0.001) and the mean right atrial pressure (r = 0.450, P<0.01) before the procedure. The antecubital venous levels of beta-endorphin in patients in New York Heart Association functional Classess Ⅱ (26.45 ± 5.39 pg / ml, n = 20) and Ⅲ (32.20 ± 4.02 pg / ml, n = 15) were significantly higher than those in control subjects (P< 0.005 and P< 0.001, respectively). The differences between Classes Ⅱ and Ⅲ were significant (P < 0.001). The plasma levels of beta-endorphin in the patients complicated with atrial fibrillation were also significantly higher than those in patients with normal sinus rhythm (33.31 ± 3.22 pg / ml, n= 13 vs 26.32± 5.07 pg / ml, n = 22, P< 0.001). In ten to fifteen minutes after commissurotomy, plasma levels of beta-endorphin in the femoral vein significantly increased from 28.20 ± 5.44 to 33.14 ± 5.72 pg / ml (P< 0.001). In seventy-two hours after the procedure, plasma beta-endorphin levels in the antecubital vein fell to 24.37 ± 2.59 pg / ml (P< 0.001 vs before PTMC and P<0.05 vs control subjects). Plasma beta-endorphin levels in the patients with atrial fibrillation (26.62 ± 2.36 pg / ml, P< 0.001 vs before PTMC and P< 0.002 vs control subjects) were still higher (P< 0.001) than those in patients with normal shins rhythm (23.05 ± 1.65 pg / ml, P< 0.001 vs before PTMC and P>50 vs control subjects. There was a significant correlation between the levels of beta-endorphin in the antecubital vein and heart rate (r = 0.502, P< 0.001), mean transmitral pressure gradient (r = 0.543, P< 0.001) or mitral valve area (r = -0.710, P< 0.001) before and 72 hours after the procedure.
文摘In this work, we have studied the vacancy formation energy of TiN alloy of structure B2 of size 10 × 10 × 10 for nitrogen percentages of 45%, 50% and 55% under the influence of temperature at 1320 K, 1420 K and 1520 K using the Modified Embedded Atom Method MEAM under the calculation code LAMMPS version 2020. This study has enabled us to understand the behavior of the TiN alloy under different nitrogen percentages in terms of total energy, vacancy formation energy, crystalline parameter, occupancy rate and order parameter. For total energy, we have shown that as temperature increases, total energy decreases, making it easier to obtain TiN at higher temperatures;reaching the value of -7344.9169 eV for the 55% nitrogen structure for the temperature of 1420 K. For the energy of formation, we have shown that the compounds obtained at 1320 K and 1520 K have a more considerable energy of formation than that obtained at 1420 K. The study of fractions and the order parameter showed us that the structure of TiN with 55% nitrogen is less likely, as the composition obtained is at most 53.35%.
文摘The reaction between high purity nickel (99.999%) and high purity tin (99.999%) was investigated in the temperature range of 232℃ - 330℃, at short periods of annealing (1 - 60 s). The reaction kinetic was studied using cross-sectional scanning electron microscope (SEM) images. The intermetallic compound (IMC) growth was analyzed using the empirical power law and a time dependence in the range of 0.26 to 0.33 was found. The morphology of the IMC was investigated by SEM in the temperature range of 235℃ - 290℃, at annealing periods of 10 s, 30 s, and 60 s by selectively etching away the remaining elementary tin. The exposed IMC displays a change in morphology with increasing annealing temperature, demonstrating that the growth velocity of certain crystallographic orientations of the IMC is strongly influenced by the annealing temperature. Additionally, coarsening and crumbling of the IMC grains is observed, and will be discussed with respect to the responsible mechanisms.
文摘Pedunculate oak and sessile oak are important natural species in the Upper Rhine Valley. The increasing mortality of these oak species has been observed since the 1980s in this region, mainly due to severe droughts. Turkey oak is known to be highly productive and drought-resistant. The goal of this article is therefore to investigate the adaptability to drought of these three young oak species growing at the same site, and to show to what extent Turkey oak can be substituted for these native oak species. Stand measurements and retrospective analyses of radial growth were performed within the framework of the eight-year-old “Mooswald” afforestation experiment in order to determine stand volume, mortality and resistance/resilience to drought for each species. Turkey oak shows significantly higher stand volume and significantly lower mortality than sessile oak. Values of these two parameters for Turkey oak and sessile oak are not significantly different from those of pedunculate oak. However, Turkey oak is not more resistant to drought than the other oak species. Sessile oak has the highest mortality and the smallest stand volume, while pedunculate oak is the least resilient to drought. These results are only a trend that must be confirmed in older stand stages and investigation in young stands must continue, supported by better monitoring and improved tools.
文摘为检测头孢氨苄中杂质的含量,特建立此方法用于测定头孢氨苄中杂质L-头孢氨苄含量。采用HPLC法,色谱条件为采用CAPCELL PAK C18 MG‖色谱柱,将0.1 mol/L磷酸二氢钠(p H值为5.0)为流动相A,甲醇为流动相B,采用梯度洗脱,流速1.5 m L/min在220nm波长处测定。经对此方法进行方法验证,头孢氨苄和L-头孢氨苄在此条件下分离度良好,专属性、准确度、重复性、检测限、定量限等均满足要求。经方法学验证结果表明,本法可用于对头孢氨苄原料中L-头孢氨苄的质量控制。
