Modular β‐cyclodextrin and polyoxyethylene ether modified water‐soluble polyacrylamide for shale hydration inhibition

A novel water‐soluble copolymer was prepared from acrylamide (AM), acrylic acid (AA), mono‐2‐O‐(allyloxy‐2‐hydroxyl‐propyl)‐β‐cyclodextrin (O‐β‐CD) and allyl alcohol polyoxyethylene ether (APEG), which was characterized with infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, ¹³C‐nuclear magnetic resonance spectrometry and static light scattering. This new copolymer combining polyglycols and the massive hydroxyl groups and cavity structure of β‐CD was investigated for inhibiting shale hydration. Based on the salt‐tolerance test, thermogravimetric‐differential scanning calorimetry‐mass spectrometer analyses, copolymer AM/AA/APEG/O‐β‐CD has made progress in the salt and temperature resistances. Moreover, the remarkable inhibiting‐hydration performance of copolymer was found as evidenced by the reduction of interlayer spacing of sodium montmorillonite and the high retention rates of indentation hardness of shale cores. Copyright © 2015 John Wiley & Sons, Ltd.     

Novel oxidative aromatic alkene cleavage with sodium nitrite under mild conditions

We have developed a simple and practical process for the oxidation of aromatic alkene to the corresponding carbonyl compounds using NaNO₂ as an oxidant. The practical utility of this oxidative process has been demonstrated in the gram-scale oxidation of 1-(tert-butyl)-4-vinylbenzene.     

Activity Enhancement of G‐Quadruplex/Hemin DNAzyme by Flanking d(CCC)

G‐quadruplex (G4)/hemin DNAzymes have been extensively applied in bioanalysis and molecular devices. However, their catalytic activity is still much lower than that of proteinous enzymes. The G4/hemin DNAzyme activity is correlated with the G4 conformations and the solution conditions. However, little is known about the effect of the flanking sequences on the activity, though they are important parts of G4s. Here, we report sequences containing d(CCC), flanked on both ends of the G4‐core sequences remarkably enhance their DNAzyme activity. By using circular dichroism and UV‐visible spectroscopy, the d(CCC) flanking sequences were demonstrated to improve the hemin binding affinity to G4s instead of increasing the parallel G4 formation, which might explain the enhanced DNAzyme activity. Meanwhile, the increased hemin binding ability promoted the degradation of hemin within the DNAzyme by H₂O₂. Furthermore, the DNAzyme with d(CCC) flanking sequences showed strong tolerance to pH value changes, which makes it more suitable for applications requiring wide pH conditions. The results highlight the influence of the flanking sequences on the DNAzyme activity and provide insightful information for the design of highly active DNAzymes.     

兖州矿区立井井筒非采动破裂的非线性预测与判别方法

厚冲积层立井井筒非采动破裂工程地质灾害是人类工程与自然环境相互作用的结果,该灾害的发生给煤矿造成巨大的经济损失,本文采用神经网络及模糊神经网络的方法对立井井筒破裂进行了预测与判别,预测与判别的结果表明,采用神经网络与模糊神经网络方法能够很好适用于立井井筒破裂的预测与判别,准确性高,能够满足实际应用的需要。     

The transmission performance degradation of the optical millimeter-wave signals by fiber chromatic dispersion

The influence of the fiber chromatic dispersion on double sideband (DSB), optical carrier suppression (OCS), and single sideband (SSB) optical mm-wave signals is investigated based on the Taylor expansion of the propagation constant and is verified by simulation. According to our theoretical results, the fading effect suppresses the signal power of the DSB optical mm-wave periodically in a cosine-like pattern, and it can be described by the zero-order Taylor expansion of the propagation constant. For the optical mm-wave with the signal modulated on two or more tones, the bit pulses of the mm-wave signal are distorted by the dispersion-inducing bit walk-off effect between tones, which is expressed by the first-order Taylor expansion of the propagation constant. Moreover, as the signal rate and the transmission distance are increased further, higher-order Taylor expansion of the propagation constant still degrades the optical mm-wave signal even if both the fading effect and the bit walk-off effect are eliminated completely. The distortion of the signal pulses of SSB optical mm-wave is derived based on the second-order Taylor expansion of the propagation constant. This degradation is verified by the simulation with the eye diagram evolution of the SSB optical mm-wave signal.     

Comparison study on structure of Si and Cu doping CrN films by reactive sputtering

CrN, CrSiN and CrCuN films were deposited by DC magnetron reactive sputtering with hot pressed pure Cr, CrSi, and CrCu targets, respectively. As substrate bias increased from −50 V to −200 V, the preferred orientation of CrN films changed from (1 1 1) to (2 0 0). And the Si doping did not change this condition. However, the Cu doping films kept (2 0 0) orientation all along. CrN films presented typical columnar structure, and the alloying of Si and Cu could restrain columnar growth leading to dense structure. The CrSiN film was composed of nanocrystallites distributed in amorphous Si₃N₄, while no amorphous phase existed in CrCuN films.     

A density functional theory study on the H2S molecule adsorption onto small gold clusters

An all-electron scalar relativistic calculation on Au_nH₂S (n = 1-13) clusters has been performed by using density functional theory with the generalized gradient approximation at PW91 level. The small gold cluster would like to bond with sulfur in the same plane and the H₂S molecule prefers to occupy the on-top and single fold coordination site in the cluster. The Au_n structures and H₂S molecule in all Au_nH₂S clusters are only slightly perturbed and still maintain their structural integrity. After adsorption, the S-H, H-H bond-lengths and most Au-Au bond-lengths are elongated, only a few Au-Au bond-lengths far from H₂S molecule are shortened. The reactivity enhancement of H₂S molecule is obvious and the strong gold-sulfur bond is observed expectedly. The most favorable adsorption takes place in the case that the H₂S molecule is adsorbed by an even-numbered Au_n cluster and becomes Au_nH₂S cluster with even number of valence electrons. It is believed that the strong scalar relativistic effect is favorable to H₂S molecule adsorption onto small gold clusters and is also one of the important reasons for the strong gold-sulfur bond.     

有限温度下无质量ψ^3理论中角度红外发散的正规化

讨论了无质量标量场ψ＾３理论三圈真空图中的角度红外发散以及它的维数正规化方案，并给出了它在Ｄ维空间的解析表达式。     

共价固体氮化碳的电弧法制备

β-C_3N_4是一种首先运用固体量子理论和计算机技术,通过人工设计具有理想成分和结构以及预期优异性能的新材料,Liu和Cohen的理论计算表明:一种晶体结构类似β-Si_3N_4的 C—N化合物具有非常短的共价键(平均键长0.147nm),其体变模量为4.27×10~5MPa,接近金刚石的4.43×10~5MPa。这预示它具有可与金刚石相媲美的硬度。此外,它的结合能计算值 (81.5eV/cell)大于β-Si_3N_4(74.8eV/cell),表明可能存在亚稳态结构。近年来,人们采用了 CH_4和H_2的等离子体分解,C—N—H有机物热解和冲击波压缩等方法,以期合成这种 C—N共价键固体。但是由于C—H和N—H键的稳定性,阻碍了β-C_3N-4的形成。直到1993年,哈佛大学的Niu等人首先用激光蒸发和原子束喷注相结合的方法,成功地获得了这种共价固体氮化碳薄膜。作者尝试采用高纯石墨电极在氮气中电弧放电的方法,代替激光蒸发法,也获得了这种材料。用X光电子能谱(XPS)证实了C—N共价键的生成,用X射线衍射 (XRD)和透射电镜选区电子衍射(TED)检验其结构,和Niu等人的结果基本相符。     

Dielectric properties of aqueous solutions of α- -glucose at 915 MHz

Using a cavity perturbation technique, dielectric properties of aqueous solutions of α- -glucose at 915 MHz were investigated at concentrations varying from 10 to 70% (w/w) and temperatures ranging from 25–85°C. The dielectric constant increased with temperature but decreased with concentration, whereas the loss factor did the inverse. Dielectric properties for higher concentration glucose solutions showed the greatest variation at higher temperatures. Predictive models of the dielectric properties as functions of concentration and temperature were developed by stepwise regression. Such models are useful in estimating the volumetric heating of these solutions by microwave energy, studying the dielectric behavior of the glucose solutions, and chemical reactions involving glucose in aqueous solutions in a microwave field.