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1.
A remarkable nonlinearity has been observed for electric transport in K-TCNQ (potassium tetracyanoquinodimethane) quasi-one-dimensional
conductor. The negative differential resistance region appears afterV
m (turn over voltage), beyond which voltage goes down with increase of current. A possible mechanism is discussed in terms
of dynamics of charged solitons and domain walls in one-dimensional molecular stacks of these types of crystals. 相似文献
2.
3.
Yuuzou Kawahara 《Corrosion Science》2002,44(2):223-245
Corrosion products on two typical materials, SA213-T12 steel and alloy 625 exposed to the actual combustion gas, were analyzed in addition to laboratory tests for penetration of corrosive matter. It has been clarified that corrosion products of oxides containing a little chlorides and sulphides show lamellar structures and that at the alloy-scale interface, chlorination, sulphidation, and oxidation occur under a low PO2-high PCl2 condition. The formation of scale structures and the effect of corrosion-resistant alloying elements can be explained according to the stability tendencies of metals, chlorides, and oxides in the M-Cl-O equilibrium diagrams. The severity of corrosion environments at the interface is influenced by the penetration extent of corrosive matters through deposits and scales, and the protective effects of oxide films derived from alloying elements play an important role in preventing the corrosion. On the other hand, it has been shown that thermal fluctuation characterized in this kind of environment makes the lamellar scale structures and sometimes breaks and peels off the scale, and thus accelerates the corrosion. On the basis of the above mentioned knowledge, a new corrosion model is presented. 相似文献
4.
A. Nagashima 《International Journal of Thermophysics》1995,16(5):1069-1086
The experimental determination of thermophysical properties has been greatly improved by the introduction of laser technology. The laser beam is used for sensing and also for heating (or exciting) the specimen. The advantage of using a laser beam is most strongly felt in the measurement of the thermal conductivity or the thermal diffusivity, which are some of the most difficult properties to measure. Interesting features of new techniques for investigating various aspects of thermal conductivity in fluids and solids are reviewed. An optical method, the so-called forced Rayleigh scattering method, or the laser-induced optical-grating method, has been developed and used extensively by the present author's group. The method is a high-speed remote-sensing method which can also quantitatively detect anisotropy, namely, direction dependence of heat conduction in the material. It was used for determination of the thermal diffusivity and its anisotropic behavior for high-temperature materials such as molten salts, liquid crystals, extended polymer samples, and flowing polymer melts under shear. Interesting applications of the method were demonstrated also for thermal diffusivity mapping and microscale measurement.Invited paper presented at the Twelfth symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A. 相似文献
5.
Cheng Xie Lei Xu Jinhui Peng Libo Zhang Xueqian Wang Jianying Deng Mickael Capron Vitaly Ordomsky 《Advanced functional materials》2023,33(14):2213782
Ti3C2 MXenes with different halogen modifications are prepared rapidly and efficiently by microwave molten salt method, and the MXene surface functional group modification is successfully achieved to address the problems of low purity, complex functional groups, and uncontrollable energy band structure of MXenes obtained by traditional liquid phase etching. Among them, the modification of the iodine (I) functional group onto the surface of Ti3C2 changes the energy band structure and band gap, resulting in easier photoexcitation and more photogenerated carriers. The increased Fermi energy is closer to the conduction band, the decreased surface work function weakens the electron confinement ability. The photogenerated carriers can migrate to the surface of the material more easily with extended lifetime, so the activity of the catalyst is improved. Further, for gaseous monomeric mercury (Hg0) photo-oxidative removal, Ti3C2-I2 exhibits 85.5% efficiency of Hg0 photo-oxidative removal under visible light. Based on the experimental characterization and density functional theory calculations, a mechanism for the photo-oxidative removal of Hg° from Ti3C2-I2 MXene is proposed, which provides a valuable strategy for studying Ti3C2 MXenes in the field of photocatalysis. 相似文献
6.
Yingjie Kong Wenjian Shen Haoyu Cai Wei Dong Cong Bai Juan Zhao Fuzhi Huang Yi-Bing Cheng Jie Zhong 《Advanced functional materials》2023,33(25):2300932
Despite the rapid developments are achieved for perovskite solar cells (PSCs), the existence of various defects in the devices still limits the further enhancement of the power conversion efficiency (PCE) and the long-term stability of devices. Herein, the efficient organic potassium salt (OPS) of para-halogenated phenyl trifluoroborates is presented as the precursor additives to improve the performance of PSCs. Studies have shown that the 4-chlorophenyltrifluoroborate potassium salt (4-ClPTFBK) exhibits the most effective interaction with the perovskite lattice. Strong coordination between BF3−/halogen in anion and uncoordinated Pb2+/halide vacancies, along with the hydrogen bond between F in BF3− and H in FA+ are observed. Thus, due to the synergistic contribution of the potassium and anionic groups, the high-quality perovskite film with large grain size and low defect density is achieved. As a result, the optimal devices show an enhanced efficiency of 24.50%, much higher than that of the control device (22.63%). Furthermore, the unencapsulated devices present remarkable thermal and long-term stability, maintaining 86% of the initial PCE after thermal test at 80 °C for 1000 h and 95% after storage in the air for 2460 h. 相似文献
7.
Chun-Hao Chen Fan Hu Zhen-Huang Su Yan-Jun Yu Kai-Li Wang Yi-Ran Shi Jing Chen Yu Xia Xing-Yu Gao Zhao-Kui Wang Liang-Sheng Liao 《Advanced functional materials》2023,33(15):2213661
The substrates of conventional flexible perovskite solar cells (FPSCs) are thermoplastic polymer material polyethylene naphthalate (PEN), which will deform during high temperature annealing process. In addition, lead iodide (PbI2) permanently formed and the substrate undergoes reversible deformation from 20 °C to 200 °C and back to 20 °C. Therefore, to balance the substrate supporting capacity and the crystalline quality of narrow band gap α-phase formamidinium lead iodide (α-FAPbI3), an annealing process of 120 °C for 30 minutes is determined. Additionally, there will also be a large number of gaps and lattice strain at the perovskite grain boundaries during the annealing process as the FAPbI3 phase transition is accompanied by much lattice shrinkage. As a result, 1,6-hexanediammonium diiodide (HADI) is chosen to passivate the defects and release the stress of perovskite film. Therefore, a recorded 1.4% extended stretch rate of the flexible film is attained. Finally, the champion PCE of 21.14% under AM 1.5G and 31.52% under 1062 lux is achieved after HADI treatment, accompanied by a better long-term and mechanical stability. This study provides annealing process optimization and stress relief strategies for the further development of narrow band gap FPSCs. 相似文献
8.
Maja Đanić Nebojša Pavlović Bojan Stanimirov Saša Vukmirović Katarina Nikolić Danica Agbaba 《Drug development and industrial pharmacy》2016,42(4):661-667
AbstractIntroduction: Distribution coefficient (D) is useful parameter for evaluating drugs permeability properties across biological membranes, which are of importance for drugs bioavailability. Given that bile acids are intensively studied as drug permeation-modifying and -solubilizing agents, the aim of this study was to estimate the influence of sodium salts of cholic (CA), deoxycholic (DCA) and 12-monoketocholic acids (MKC) on distribution coefficient of simvastatin (SV) (lactone [SVL] and acid form [SVA]) which is a highly lipophilic compound with extremely low water solubility and bioavailability.Methods: LogD values of SVA and SVL with or without bile salts were measured by liquid–liquid extraction in n-octanol/buffer systems at pH 5 and 7.4. SV concentrations in aqueous phase were determined by HPLC-DAD. Chem3D Ultra program was applied for computation of physico-chemical properties of analyzed compounds and their complexes.Results: Statistically significant decrease in both SVA and SVL logD was observed for all three studied bile salts at both selected pH. MKC exerted the most pronounced effect in the case of SVA while there were no statistically significant differences between observed bile salts for SVL. The calculated physico-chemical properties of analyzed compounds and their complexes supported experimental results.Conclusions: Our data indicate that the addition of bile salts into the n-octanol/buffer system decreases the values of SV distribution coefficient at both studied pH values. This may be the result of the formation of hydrophilic complexes increasing the solubility of SV that could consequently impact the pharmacokinetic parameters of SV and the final drug response in patients. 相似文献
9.
通过在700℃下的CaCl_2和NaCl混合熔盐中电化学还原ZrO_2制备得到了Zr的低价金属氧化物ZrO0.35,该低价金属氧化物作为铂催化剂载体催化甲醇显示了很高的催化活性和稳定性。分析了该催化剂的组成结构和电化学行为。结果显示,在酸性介质中该载体能够有效地提高铂纳米颗粒对甲醇和CO的催化活性。有两种机制可以解释其表现:一是电子协同效应,即Zr原子的电子转移到Pt原子,Pt与CO的相互作用力减弱,从而抑制了Pt中毒;另外一方面是Pt和金属载体的协同效应,它可以有效地移除和氧化CO的中间体。 相似文献
10.
以2-乙基-2-硝基-1,3-丙二醇为原料,经酯化、叠氮化两步反应,合成出了1,3-二(叠氮乙酰氧基)-2-乙基-2-硝基丙烷(ENPEA),总收率为83%。利用红外光谱、核磁共振、元素分析对ENPEA的结构进行了表征。探讨了叠氮化反应的影响因素,确定其最佳反应条件为:n(Na N3)n(ENPE)为2.21.0,混合溶剂中水占总体积的13%~20%,反应时间2 h;性能测试得到ENPEA的玻璃化转变温度为-43.4℃,热分解峰温为252.4℃,密度为1.34 g/cm3,特性落高为120.2 cm(落锤2 kg),爆炸概率为4%(摆角66°)。 相似文献