Reactivity of triacetone triperoxide and diacetone diperoxide: Insights from nuclear Fukui function

Triacetone triperoxide (TATP) is more sensitive than diacetone diperoxide (DADP) in the solid-state explosion. To explain this reactivity difference, we analyzed the electronic structures and properties of the crystals of both compounds by using Ab initio method to calculate the structures of their individual molecules as well as their lattice structures and particularly calculating Nuclear Fukui function to gain insight into the sensitivity of the initial, rate-determining step of their decomposition. Our results indicate that TATP and DADP crystal structures exhibit significantly different electronic properties. Most notably, the electronic structure of the TATP crystal shows asymmetry among its reactive oxygen atoms as supported by magnitudes of their nuclear Fukui functions. The greater explosion sensitivity of crystalline TATP may be attributed to the properties of its electronic structure. The electronic calculations provided valuable insight into the decomposition sensitivity difference between TATP and DADP crystals.     

Ca2+、ATP、ADP和AMP对鸭胸肉中肌动球蛋白解离的影响

为了解促进肌动球蛋白解离的因素,从鸭胸肉中提取肌动球蛋白,研究Ca2+、三磷酸腺苷（adenosinetriphosphate,ATP）及其降解产物对肌动球蛋白的解离效果。通过蛋白质免疫印迹技术测定肌动蛋白含量的变化来研究肌动球蛋白的解离情况。研究发现,7.5～64 mmol/L Ca2+对肌动球蛋白的解离无促进作用（P＞0.05）,而Ca2+浓度升高到200 mmol/L时,能显著促进肌动球蛋白的解离（P＜0.05）;单独的ATP对肌动球蛋白的解离无促进作用（P＞0.05）;Ca2+和ATP共同作用于肌动球蛋白后,可显著促进肌动球蛋白的解离（P＜0.05）;二磷酸腺苷（adenosine diphosphate,ADP）、一磷酸腺苷（adenosine monophosphate,AMP）均可显著促进肌动球蛋白的解离（P＜0.05）,且不同浓度处理组间无显著性差异（P＞0.05）。因此,可以推断ADP、AMP以及Ca2+和ATP的共同作用对肌动球蛋白的解离有促进作用。     

云南钛铁矿砂矿磁选试验研究

云南钛铁矿石中主要有用矿物为钛铁矿、钛磁铁矿,矿石泥化较严重,针对该矿石进行了磁选试验研究。对原矿采用选择性擦洗解离,可以得到TiO2品位35.31%,产率78.25%的+0.030mm产品及TiO2品位8.46%,产率21.75%的-0.030mm产品。+0.030mm粒级采用弱磁除铁,弱磁尾矿采用分级-强磁选工艺进行选钛试验,对弱磁精矿再磨后采用弱磁-强磁工艺进行钛、铁分离;-0.030mm粒级采用脱泥-磁选工艺进行细粒选钛试验。最终可得到TiO2品位48.83%的钛精矿,回收率85.51%,TFe品位56.62%的铁精矿,回收率25.17%。该工艺合理可行,选矿指标较为理想。      

Synthesis of helical carbon nanofibres and its application in hydrogen desorption

In this communication, we report the synthesis of helical carbon nanofibres (HCNFs) by employing hydrogen storage intermetallic LaNi₅ as the catalyst precursor. It was observed that oxidative dissociation of LaNi₅ alloy (2LaNi₅ + 3/2O₂ → La₂O₃ + 10Ni) occurred during synthesis. The Ni particles obtained through this process instantly interacted with C₂H₂ and H₂ gases, and fragmented to nanoparticles of Ni (∼150 nm) with polygonal shape. These polygonal shapes of Ni nanoparticles were decisive for the growth of helical carbon nanofibres (HCNFs) at 650 °C. TEM, SAED and EDAX studies have shown that HCNFs have grown on Ni nanoparticles. Typical diameter and length of the HCNFs are ∼150 nm and 6-8 μm respectively. BET surface area of these typical HCNFs has been found to be 127 m²/g. It was found that at temperature 750 °C, spherical shapes of Ni nanoparticles were produced and decisive for the growth of planar carbon nanofibres (PCNFs). The diameter and length of the PCNFs are ∼200 nm and 6-8 μm respectively. In order to explore the application potential of the present as-synthesized CNFs, they were used as a catalyst for enhancing the hydrogen desorption kinetics of sodium aluminum hydride (NaAlH₄). We have found that the present as-synthesized HCNFs, with metallic impurities, indeed work as an effective catalyst. The pristine NaAlH₄ and 8 mol% as-synthesized HCNFs admixed NaAlH₄, at 160 °C-180 °C and for the duration of 5 h, liberate 0.8 wt% and 4.36 wt% of hydrogen, respectively. Thus there is an enhancement of ∼5 times in kinetics when as-synthesized HCNFs are used as the catalyst. To the best of our knowledge, the use of hydrogen storage alloy LaNi₅ as the catalyst precursor for the growth of HCNFs has not yet been done and thus represents a new feature relating to the growth of HCNFs. Furthermore, we have shown that the as-synthesized HCNFs work as an effective new catalyst for improving the dehydrogenation kinetics of the complex hydride, NaAlH₄.     

The impact of repetition-induced familiarity on agreement with weak and strong arguments.

Repeated statements are perceived as more valid than novel ones, termed the illusion of truth effect, presumably because repetition imbues the statement with familiarity. In 3 studies, the authors examined the conditions under which and the processes by which familiarity signals from repetition and argument quality signals from processing of message content influenced agreement with persuasive arguments. Participants with low or high motivation to process information were presented persuasive arguments seen once or twice. In all 3 studies, repetition increased the persuasiveness of weak and strong arguments when little processing of message content occurred. Two of the studies used a process dissociation procedure to reveal that both greater controlled processing (which reflected argument content) and the greater automatic influence of familiarity (which reflected repetition) were associated with increased acceptance of strong arguments but that greater controlled processing dissipated the benefits of familiarity for agreement with weak arguments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Latest progress in numerical simulations on multiphase flow and thermodynamics in production of natural gas from gas hydrate reservoir

Natural gas hydrates are promising potential alternative energy resources. Some studies on the multiphase flow and thermodynamics have been conducted to investigate the feasibility of gas production from hydrate dissociation. The methods for natural gas production are analyzed and several models describing the dissociation process are listed and compared. Two prevailing models, one for depressurization and the other for thermal stimulation, are discussed in detail. A comprehensive numerical method considering the multiphase flow and thermodynamics of gas production from various hydratebearing reservoirs is required to better understand the dissociation process of natural gas hydrate, which would be of great benefit to its future exploration and exploitation.     

氯溴双卤代烷烃分子构型和光谱对烷基链长依赖关系的研究

氯溴双卤代烷烃在太阳紫外光辐射下解离生成游离态的氯和溴自由基,它们是破坏臭氧的主要元凶之一。利用B3LYP/6-311++G(d,p)方法对氯溴双卤代烷烃分子CnH2nBrCl(n=1~16)进行分子构型优化以及红外光谱的计算。根据数据进行分析比较,得到了氯溴双卤代烷烃C-Br键和C-Cl键的键长、键角等构型参数随烷基支链长度增加(n为1~16)的变化趋势图。研究讨论了氯溴双卤代烷烃的红外光谱相关振动随烷基支链长度增加的重要变化规律。     

Identification of Highly Active Iron Sites in N2O-Activated Fe/MFI

Reduction in an H₂ flow at 600 °C of Fe/MFI prepared by chemical vapor deposition, followed by its exposure to N₂O at 250 °C, produces a highly active state characterized by an unusual TPR spike at 200 °C. In situ X-ray absorption near-edge structure, X-ray absorption fine structure data and literature data on DFT calculations suggest that in this state some Fe will be present in the oxidation state of Fe⁴⁺.     

A mathematical model of immunohistochemical preparations, which provides quantitative predictions

A mathematical model of the reaction between primary antibody and epitope is described using the Law of Mass Action to define the reaction quantitatively. The model explains some of the peculiar properties of immunohistochemical preparations. It also predicts that antibody excess over epitope will not increase staining intensity for very avid primary antibodies. This property can be exploited to measure the amount of epitope in histological sections. The assumptions of the model are not specific to immunohistochemistry, and such reasoning should be widely applicable to tests based on highly avid detection systems with high amplification of the initial signal.     

关于弱酸及单弱盐性质的补充

本文推导出了弱酸及单弱盐的离解度的计算公式；提出了判断弱酸相对强弱和单弱盐水解程度相对大小的又一物理量——极限离解度．