Polyparaphenylene(PPP) is prepared by AlCl 3-CuCl 2 catalysts with benzene as the monomer and is doped by chemical method and N + ion implantation. The influences of the concentration, temperature and time of chemi...Polyparaphenylene(PPP) is prepared by AlCl 3-CuCl 2 catalysts with benzene as the monomer and is doped by chemical method and N + ion implantation. The influences of the concentration, temperature and time of chemical doping and the dose, energy and temperature of ion implantation, on PPP conductivity are investigated. The results showed that the conductivity of PPP can be improved 4～5 orders of magnitude by ion implantation and the conductivity of PPP can reach about 0.11 S·cm -1 by chemical doping. The comparison of stability of the material conductive behavior by using the two doping methods is presented. It shows that ion implantation is better than chemical doping in stabilizing the electric conductive behavior for the material.展开更多
A new organic semiconductor tartaric acid doped salt of emeraldine polyaniline (PANI-C 4H 6O 6) has been obtained by the method of oxidative polymerization of monomeric aniline with ammonium persulfate in acidic solut...A new organic semiconductor tartaric acid doped salt of emeraldine polyaniline (PANI-C 4H 6O 6) has been obtained by the method of oxidative polymerization of monomeric aniline with ammonium persulfate in acidic solution. The structure was characterized by Fourier Transform Infrared technique (FTIR) and X-ray diffraction (XRD). The temperature dependence dc conductivity δ dc ( T ) shows a semiconductor behavior and follows the quasi one dimensional variable range hopping (Q1D-VRH) model. Data on δ dc ( T ) are also discussed.展开更多
Formulated and endorsed by the international scientific community,the Tianjin Biosecurity Guidelines are a set of ten guiding principles and standards of conduct designed to promote responsible sciences and strengthen...Formulated and endorsed by the international scientific community,the Tianjin Biosecurity Guidelines are a set of ten guiding principles and standards of conduct designed to promote responsible sciences and strengthen biosecurity governance at national and institutional levels.It may be used to develop new or enhance,supplement,and update the existing codes of conduct adaptive to a specific context and responsive to the bio-risks arising from the rapid advances in biological sciences.展开更多
We investigated the electronic heat capacity, thermal conductivity, and resistivity of UN using Quantum Espresso and EPW code. GGA, PBEsol functional was used. The calculated electronic heat coefficient was found to b...We investigated the electronic heat capacity, thermal conductivity, and resistivity of UN using Quantum Espresso and EPW code. GGA, PBEsol functional was used. The calculated electronic heat coefficient was found to be significantly reduced (0.0176 J<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>mol<sup><span style="white-space:nowrap;">-</span>1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>K<sup><span style="white-space:nowrap;">-</span>2</sup> versus 0.0006 J<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>mol<sup><span style="white-space:nowrap;">-</span>1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>K<sup><span style="white-space:nowrap;">-</span>2</sup>) when the non-local hybrid functional (B3LYP) was used. Furthermore, we calculated electrical resistivity using a very transparent Ziman’s formula for metals with the Eliashberg transport coupling function as implemented in EPW code for non-spin-polarized calculations. The number of mobile electrons in UN, as a function of temperature, was derived from the ratio of the calculated resistivity and available experimental data. The electronic thermal conductivity was evaluated from the calculated electronic resistivity via Wiedemann-Franz law with the number of mobility electrons (<em>n<sub>av</sub></em>) incorporated (averaged over the temperature range 300 K - 1000 K). Both the electronic thermal conductivity and resistivity, as calculated using newly evaluated <em>n<sub>av</sub></em>, compare well with experimental data at ~700 K, but to reproduce the observed trend as a function of temperature, the number of mobile electrons must decrease with the temperature as evaluated.展开更多
The paper examines the utility of codes of conduct for promoting responsible science and chemical, biological, radiological, and nuclear (CBRN) security education. It reviews the growing international consensus on the...The paper examines the utility of codes of conduct for promoting responsible science and chemical, biological, radiological, and nuclear (CBRN) security education. It reviews the growing international consensus on the need for developing codes of conduct as a way of engaging scientists with the broader social, ethical, and legal implications of their work and examines the ongoing efforts to develop and promulgate such codes. The paper argues that the effectiveness of codes of conduct requires sustained and tailored effort in promoting education and awareness of security issues among scientists.展开更多
文摘Polyparaphenylene(PPP) is prepared by AlCl 3-CuCl 2 catalysts with benzene as the monomer and is doped by chemical method and N + ion implantation. The influences of the concentration, temperature and time of chemical doping and the dose, energy and temperature of ion implantation, on PPP conductivity are investigated. The results showed that the conductivity of PPP can be improved 4～5 orders of magnitude by ion implantation and the conductivity of PPP can reach about 0.11 S·cm -1 by chemical doping. The comparison of stability of the material conductive behavior by using the two doping methods is presented. It shows that ion implantation is better than chemical doping in stabilizing the electric conductive behavior for the material.
文摘A new organic semiconductor tartaric acid doped salt of emeraldine polyaniline (PANI-C 4H 6O 6) has been obtained by the method of oxidative polymerization of monomeric aniline with ammonium persulfate in acidic solution. The structure was characterized by Fourier Transform Infrared technique (FTIR) and X-ray diffraction (XRD). The temperature dependence dc conductivity δ dc ( T ) shows a semiconductor behavior and follows the quasi one dimensional variable range hopping (Q1D-VRH) model. Data on δ dc ( T ) are also discussed.
基金supported by grants from the National Key Research and Development Program of China(Grant nos.2019YFA0904600 and 2020YFA0908600).
文摘Formulated and endorsed by the international scientific community,the Tianjin Biosecurity Guidelines are a set of ten guiding principles and standards of conduct designed to promote responsible sciences and strengthen biosecurity governance at national and institutional levels.It may be used to develop new or enhance,supplement,and update the existing codes of conduct adaptive to a specific context and responsive to the bio-risks arising from the rapid advances in biological sciences.
文摘We investigated the electronic heat capacity, thermal conductivity, and resistivity of UN using Quantum Espresso and EPW code. GGA, PBEsol functional was used. The calculated electronic heat coefficient was found to be significantly reduced (0.0176 J<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>mol<sup><span style="white-space:nowrap;">-</span>1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>K<sup><span style="white-space:nowrap;">-</span>2</sup> versus 0.0006 J<span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>mol<sup><span style="white-space:nowrap;">-</span>1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span>K<sup><span style="white-space:nowrap;">-</span>2</sup>) when the non-local hybrid functional (B3LYP) was used. Furthermore, we calculated electrical resistivity using a very transparent Ziman’s formula for metals with the Eliashberg transport coupling function as implemented in EPW code for non-spin-polarized calculations. The number of mobile electrons in UN, as a function of temperature, was derived from the ratio of the calculated resistivity and available experimental data. The electronic thermal conductivity was evaluated from the calculated electronic resistivity via Wiedemann-Franz law with the number of mobility electrons (<em>n<sub>av</sub></em>) incorporated (averaged over the temperature range 300 K - 1000 K). Both the electronic thermal conductivity and resistivity, as calculated using newly evaluated <em>n<sub>av</sub></em>, compare well with experimental data at ~700 K, but to reproduce the observed trend as a function of temperature, the number of mobile electrons must decrease with the temperature as evaluated.
文摘The paper examines the utility of codes of conduct for promoting responsible science and chemical, biological, radiological, and nuclear (CBRN) security education. It reviews the growing international consensus on the need for developing codes of conduct as a way of engaging scientists with the broader social, ethical, and legal implications of their work and examines the ongoing efforts to develop and promulgate such codes. The paper argues that the effectiveness of codes of conduct requires sustained and tailored effort in promoting education and awareness of security issues among scientists.
