Catalytic oxidation of naphthalene using a Pt/Al2O3 catalyst

Polycylic aromatic hydrocarbons (PAHs) are listed as carcinogenic and mutagenic priority pollutants, belonging to the environmental endocrine disrupters. Most PAHs in the environment stem from the atmospheric deposition and diesel emission. Consequently, the elimination of PAHs in the off-gases is one of the priority and emerging challenges. Catalytic oxidation has been widely used in the destruction of organic compounds due to its high efficiency (or conversion of reactants), its economic benefits and good applicability.

This study investigates the application of the catalytic oxidation using Pt/γ-Al₂O₃ catalysts to decompose PAHs and taking naphthalene (the simplest and least toxic PAH) as a target compound. It studies the relationships between conversion, operating parameters and relevant factors such as treatment temperatures, catalyst sizes and space velocities. Also, a related reaction kinetic expression is proposed to provide a simplified expression of the relevant kinetic parameters.

The results indicate that the Pt/γ-Al₂O₃ catalyst used accelerates the reaction rate of the decomposition of naphthalene and decreases the reaction temperature. A high conversion (over 95%) can be achieved at a moderate reaction temperature of 480 K and space velocity below 35,000 h⁻¹. Non-catalytic (thermal) oxidation achieves the same conversion at a temperature beyond 1000 K. The results also indicate that Rideal–Eley mechanism and Arrhenius equation can be reasonably applied to describe the data by using the pseudo-first-order reaction kinetic equation with activation energy of 149.97 kJ/mol and frequency factor equal to 3.26 × 10¹⁷ s⁻¹.     

Molecular packing and phase transitions of side-chain liquid crystalline polymethacrylates based on p-methoxyazobenzene

The phase structures and transition behaviors of a series of side-chain liquid crystalline (LC) polymethacrylates based on p-methoxyazobenzene (PMnAzs, n = 6, 8, 10, 12) were studied using differential scanning calorimetry, one- and two-dimensional (1D and 2D) wide-angle X-ray diffraction, and Fourier transform infrared spectroscopic experiments. The LC phase transition of PMnAz follows the sequence of smectic A (SmA) ? nematic (N) ? isotropic (I). For PM10Az and PM12Az, the transition of SmA-to-N is not complete upon heating. In the low-temperature SmA phase, the polymers adopt a fully interdigitated side-chain packing with the smectic layer period almost identical to the side-chain length. For all the four samples, the first-order diffraction of the SmA structure only renders when the temperature approaches the transition of SmA ? N, with the intensity much lower than that of the second-order diffraction. The absence of the first-order diffraction at low temperatures is ascribed to the possible matching of the electron densities between the center portion of the side-chain sublayer and the main-chain sublayer of the SmA structure. Since only the mesogens from the same main-chain sublayer can stack parallel together, the distribution of the azobenzene domains may cause some sort of density undulation within the smectic layer. Among the samples, PM6Az presents the strongest undulation with some additional orders. We also examined the annealing effect on the H-aggregation of PMnAzs. It is found that isothermal annealing at a temperature slightly higher than the T_g of PM8Az and PM10Az can significantly enhance the UV absorption at 326 nm, indicating a further development of H-aggregation. However, for PM6Az and PM12Az, the UV–vis spectrum of the annealed sample is nearly identical to that without annealing.     

Biomolecules-Incorporated Metal-Organic Frameworks Gated Light-Sensitive Organic Photoelectrochemical Transistor for Biodetection

Incorporating biomolecules into metal-organic frameworks (MOFs) as exoskeletons to form biomolecules-MOFs biohybrids has attracted great attention as an emerging class of advanced materials. Organic devices have been shown as powerful platforms for next-generation bioelectronics, such as wearable biosensors, tissue engineering constructs, and neural interfaces. Herein, biomolecules-incorporated MOFs as innovative gating module is realized for the first time, which is exemplified by biocatalytic precipitation (BCP)-oriented horseradish peroxidase (HRP)-embedded zeolitic imidazolate framework-90 (HRP@ZIF-90)/CdIn₂S₄ gated organic photoelectrochemical transistor under light illumination. In connection to a sandwich immunocomplexing targeting the model analyte human IgG, the IgG-dependent generation of H₂O₂ and the tandem HRP-triggered BCP reaction can cause the in situ blocking of the pore network of ZIF-90, leading to variant gating effect with corresponding responses of the device. This representative biodetection achieved good analytical performance with a wide linear range and a low detection limit of 100 fg mL⁻¹. In the view of the plentiful biomolecule-MOF complexes and their potential interactions with organic systems, this study provides a proof-of-concept study for the generic development of biomolecules-MOFs-gated electronics and beyond.     

基于夹层氮化硅波导的可见-中红外超连续谱特性研究

提出一种低厚度氮化硅-蓝宝石-氮化硅夹层波导结构。利用其色散波辐射现象和中红外相位匹配条件,结合波导脉冲传输模型,讨论了夹层波导不同物理尺寸对相位匹配点和光谱展宽的影响,数值模拟获得了0.5~4 μm的超连续谱展宽,并且在-40 dB水平下具有更远中红外色散波产生。通过该模型,详细解释了非线性波导脉冲传输的潜在机制。理论模型分析表明,通过优化氮化硅及蓝宝石夹层的物理尺寸,进而改变相位匹配条件,可以在较宽的波长范围内控制色散波的位置。     

基于相关性反馈的开源系统跨层需求追踪方法

大型复杂软件系统的需求分析与生成是一个由上而下逐层分解的过程,跨层需求间追踪关系的构建对于项目的管理、开发与演化都至关重要.开源系统的松耦合贡献方式需要每位参与者能便捷地理解需求的来龙去脉及需求状态,这依赖跨层需求间的追踪.问题描述日志是开源系统中需求的常见呈现方式,其无固定模板要求,内容多样(含文本、代码、调试信息等),术语使用自由,跨层需求间抽象层次大,给自动追踪带来极大的挑战.提出一种面向关键特征维度的相关性反馈方法,通过静态分析项目代码结构,抽取代码相关术语及其间的关联强度,构建代码词汇库,以缓解跨层需求的抽象层次差距及用语不统一的问题;通过度量词汇对需求描述的重要性并基于此筛选关键特征维度,以对查询语句进行针对性的优化,有效减少需求描述长度、内容形式等方面的噪音.通过在3个开源系统需求集上针对两个场景的实验,表明所提方法相比基线方法在跨层需求追踪方面的优越性,相比VSM、Standard Rocchio和Trace BERT, F2值的最大提升分别可达29.01%、7.45%和59.21%.     

Using metal/organic junction engineering to prepare an efficient organic base-modulation triode and its inverter

In this study, we investigated the influence of a buffer layer of molybdic oxide (MoO₃) at the metal/organic junction on the behavior of organic base-modulation triodes. The performance of devices featuring MoO₃/Al as the emitter electrode was enhanced relative to that of corresponding devices with Au and Ag, presumably because of the reduced in the contact barrier and the prevention of metal diffusion into the organic layer. The device exhibited an output current of ?16.1 μA at V_B = ?5 V and a current ON/OFF ratio of 10³. Using this architecture, we constructed resistance–load inverters that exhibited a calculated gain of 6.     

A simple and effective process for fabrication of Gd0.1Ce0.9O1.95 solid electrolyte ceramics

Ce_0.9Gd_0.1O_1.95 ceramics were prepared using a simple and effective process in this study. Without any prior calcination, the mixture of raw materials was pressed and sintered directly. The reaction of the raw materials occurred during the heating up period by passing the calcination stage in the conventional solid-state reaction method. More than 99.5% of theoretical density was obtained for Ce_0.9Gd_0.1O_1.95 sintering at 1500–1600 °C. Fine grains (<1 μm) formed in pellets sintered at 1450 °C. The homogeneity of grains increased with the sintering temperature. The grains grew to >4.5 μm in pellets sintered at 1600 °C. The reactive-sintering process is proved to be a simple and effective method in preparing Ce_0.9Gd_0.1O_1.95 ceramics for solid electrolyte application.     

复合酶法修饰糯米淀粉分支结构及其物化性能研究

目的 提高糯米淀粉的物化性质及其加工性能。方法 以糯米淀粉为受体, 以不同直链淀粉(小麦、玉米、大米)或麦芽糖为供体, 采用α-淀粉酶和分支酶复合酶, 对糯米淀粉进行分子结构修饰, 测定改性前后糯米淀粉的分支度、溶解度、糊化和老化性质。结果 糯米淀粉通过复合酶法改性能够显著地提高改性淀粉的分支度; 改性后的淀粉易于糊化, 且糊化液的均匀性和透明度较好。通过DSC测定改性前后热力学性质, 发现改性淀粉未出现吸收峰, 表明淀粉结晶区中的长链被破坏, 从而形成高短链数的改性淀粉; 淀粉经过改性后得到可溶性淀粉。结论 糯米淀粉加入供体物质, 通过复合酶对淀粉进行改性, 能够提高改性淀粉的分支度和短链数, 制备出具有良好物化特性的改性淀粉。     

Kelly-Based Options Trading Strategies on Settlement Date via Supervised Learning Algorithms

Computational Economics - Option is a well-known financial derivative that attracts attention from investors and scholars, due to its flexible investment strategies. In this paper, we sought to...     

Synthesis of copper hexacyanoferrate nanoflake as a cathode for sodium-ion batteries

Prussian blue analogues are considered as the promising cathodes for sodium-ion batteries. Since the electrochemical properties are closely related to the morphology, the monodisperse copper hexacyanoferrate nanoflakes with highly crystalline are synthesized by a glycol-assisted coprecipitation method and a tentative synthetic mechanism is proposed to explain the formation of nanostructures. The structure and electrochemical properties are characterized by X-ray photoelectron spectroscopy, FTIR spectra and galvanostatic cycle tests, respectively. Due to the novel architecture of copper hexacyanoferrate, a high electrochemical activity is obtained, resulting a high initial coulombic efficiency of 93%, a capacity retention of 73% at 1?C after 300 cycles and 51?mAh?g^?1 is maintained at high rate of 15?C at 25?°C.