Dissociation constant of bibenzyl measured by e.s.r.

The equilibrium constant for the dissociation of bibenzyl to form benzyl radicals has been measured in dilute solutions of bibenzyl in toluene at 605°C and at 20.7 MPa (200 atm) and 13.8 MPa (133 atm) using electron spin resonance to assay the concentration of the benzyl radical. The value for K_c, the equilibrium constant expressed in terms of concentrations, was found to be 0.75×10⁻¹⁰ moll⁻¹ within a factor of 1.7 at both pressures.     

Acute dissociation after 1 night of sleep loss.

Recent research has shown that dissociative symptoms are related to self-reports of deviant sleep experiences. The present study is the 1st to explore whether sleep loss can fuel dissociative symptoms. Twenty-five healthy volunteers were deprived of sleep for 1 night. Sleepiness and dissociative symptoms were assessed every 6 hr. The authors measured both spontaneous dissociative symptoms and dissociative symptoms induced by dot-staring during sensory deprivation. Sleepiness as well as spontaneous and induced dissociative symptoms were stable throughout the day but increased during the night. These findings provide further evidence for a robust relationship between disruptions in sleep patterns and dissociative symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Realizing efficient exciton dissociation in an all-organic heterojunction photocatalyst for highly improved photocatalytic H2 evolution

Although graphitic carbon nitride is a promising photocatalyst in the field of energy conversion and environmental purification, the intrinsic properties like excitonic effects and sluggish charge transfer restrict further photocatalytic applications. To circumvent these limitations, the novel all-organic heterojunction photocatalysts were constructed by anchoring organic carbon dots (O-dots) on porous graphitic carbon nitride nanosheets (O-dots/CNS). Results demonstrated that excitons can be e?ectively dissociated into electrons and holes at the interface of O-dots/CNS heterojunction, followed by holes injected to O-dots and electrons accumulated in CNS to realize efficient charge separation. Consequently, the O-dots/CNS with the optimized hydrogen (H₂) evolution performance could be reached 1564.5 μmol h^?1g^?1 under the visible light irradiation. This work not only presents new ideas for rational design photocatalytic reaction system from exciton and charge carrier, but also broaden the applications of this new kind of organic dots in the field of energy conversion.     

Charge Photogeneration in Non-Fullerene Organic Solar Cells: Influence of Excess Energy and Electrostatic Interactions

In organic solar cells, photogenerated singlet excitons form charge transfer (CT) complexes, which subsequently split into free charge carriers. Here, the contributions of excess energy and molecular quadrupole moments to the charge separation process are considered. The charge photogeneration in two separate bulk heterojunction systems consisting of the polymer donor PTB7-Th and two non-fullerene acceptors, ITIC and h-ITIC, is investigated. CT state dissociation in these donor–acceptor systems is monitored by charge density decay dynamics obtained from transient absorption experiments. The electric field dependence of charge carrier generation is studied at different excitation energies by time delayed collection field (TDCF) and sensitive steady-state photocurrent measurements. Upon excitation below the optical gap, free charge carrier generation becomes less field dependent with increasing photon energy, which challenges the view of charge photogeneration proceeding through energetically lowest CT states. The average distance between electron–hole pairs at the donor–acceptor interface is determined from empirical fits to the TDCF data. The delocalization of CT states is larger in PTB7-Th:ITIC, the system with larger molecular quadrupole moment, indicating the sizeable effect of the electrostatic potential at the donor–acceptor interface on the dissociation of CT complexes.     

铜冶炼炉渣工艺矿物学探讨

采用化学分析、化学物相分析、显微镜观察及扫描电镜考察等工艺矿物学研究手段,分析了不同铜冶炼渣的化学组成及矿物物相组成,对铜冶炼渣中重要矿物的嵌布特征和嵌布粒度进行了系统的研究,对其利用中存在的问题进行了分析,为铜冶炼渣的综合回收利用提供了理论依据。     

Acid‐Base and Organic‐Water Distribution Equilibria for Symmetrically‐Substituted P,P′‐Dialkyl Alkylenebisphosphonic Acids

Abstract

P,P′‐dialkyl alkylenebisphosphonic acids are powerful metal extraction reagents. The acid dissociation constants for a homologous series of aqueous‐insoluble P,P′‐di‐3‐(trimethylsilyl)‐propyl and aqueous‐soluble P,P′‐diethyl methylene‐, ethylene‐ and propylene‐ bisphosphonic acids were determined in a 70∶30 w/w methanol‐water solvent by potentiometric titration and ³¹P NMR spectrometry. The values obtained for the diethyl‐substituted acids were compared with those determined in water and used to assess the effect of the medium on the aqueous acid dissociation constants of the lipophilic series of P,P′‐di‐3‐(trimethylsilyl)propyl alkylenebisphosphonic acids. The dependence of the organic/aqueous distribution equilibrium on the aqueous acid concentration was also investigated using electrospray ionization mass spectrometry. The acid dissociation and organic/aqueous distribution properties of the substituted alkylenebisphosphonic acids are discussed in terms of their influence on metal ion extraction.     

Harvesting energy via stimuli-free water/moisture dissociation by mesoporous SnO2–based hydroelectric cell and CuO as a pump for atmospheric moisture

Water dissociation, in general, requires external stimuli such as light energy or electricity. Here, we present a stimuli-free water dissociation using mesoporous SnO₂–based hydroelectric cell that can directly be exploited to generate electric power for portable applications. The device configuration is almost identical to metal-air batteries but follows altogether a different reaction pathway. The mesoporous SnO₂–based hydroelectric cell dissociates water molecule into hydroxyl ions (OH^-) and hydronium ion without any stimuli, transports hydronium ions to the opposite end, and simultaneously acts as the separator. The OH^- react with Al electrode to release the electrons, whereas hydronium ions get reduced at the Ag electrode to produce a potential difference as high as ~1000 ± 20 mV between the electrodes that is stable over 3500 hours. The device also shows its potential toward electric power generation from atmospheric moisture with the help of CuO layer that acts as moisture pump.     

硫在铜铅锌多金属矿石中浮选行为的探讨

针对原矿中铜、铅、锌矿物与黄铁矿的关系,对黄铁矿在铜与铅锌生产中的浮选影响情况和全混合、脱硫及分离作业中的行为进行了较为详细的阐述,得出了多金属铜与铅锌指标的提高关键是要处理好黄铁矿的走向的结论.     

鲕状高磷赤铁矿超细粉的气基还原实验研究

使用新开发装置对高磷赤铁矿超细粉进行气基还原实验研究.该矿中P主要以磷灰石形式嵌布于鲕状赤铁矿和其他脉石颗粒之间,但Fe和P元素未处于化学结合状态.采用超级涡流磨技术将高磷赤铁矿磨成平均粒度为2μm的超细粉,实现Fe和P元素较好的解离.还原实验结果表明,使用新开发的还原装置实现了矿粉的高度还原;粒度对还原结果的影响最显...     

Shear strength and pore pressure characteristics of methane hydrate-bearing soil under undrained condition

Hydrate exploitation requires a deep understanding on the mechanical behavior of methane hydrate-bearing sediment (MHBS). Due to the low permeability of overlying strata, partial MHBS likely exhibit failure behavior under undrained condition. Therefore, it is essential to understand the undrained shear strength and excess pore pressure behavior of MHBS for facilitating the evaluation of the stability of hydrate-bearing layer during methane hydrate recovery. This study conducted several undrained triaxial compression and hydrate dissociation tests on methane hydrate-bearing sand specimen to analyze the shear strength and excess pore pressure characteristics of MHBS under undrained condition. The experimental result shows that hydrate saturation and initial effective confining pressure significantly affect the undrained mechanical behavior of MHBS. Hydrate saturation increases the shear strength and negative excess pore pressure. High initial effective confining pressure also enhances the shear strength but suppressed the negative excess pore pressure. Hydrate saturation has a minimal effect on the undrained internal friction angle but remarkably enhances the undrained cohesion. The effective internal friction angle and cohesion exhibits an increase with the increase in hydrate saturation. Notably, completely different from the common soil, the effective undrained strength indexes are not equivalent to the drained strength indexes for MHBS, which should be careful in evaluating the stability of methane hydrate-bearing layer. In addition, the hydrate dissociation test by thermal stimulation method concludes that hydrate dissociation induces the positive excess pore pressure, axial compression, and volume expansion under undrained condition. The large deviatoric stress enhances volume expansion of MHBS but hinders the generation in excess pore pressure during hydrate dissociation. These findings significantly contribute to the safe exploitation process of methane hydrate.