Low-Temperature Solid State Synthesis and Characterization of Superconducting Vanadium Nitride

Superconducting vanadium nitride （VN） is successfully synthesized by a solid-state reaction of vanadium pentox- ide, sodium amide and sulfur in an autoclave at a relatively low temperature （240-400℃）. The obtained samples are characterized by x-ray diffraction, x-ray photoelectron spectroscopy and transmission electron microscopy. The result of the magnetization of the obtained VN product as a function of temperature indicates that the onset superconducting transition temperature is about 8.4K. Furthermore, the possible reaction mechanism is also discussed.

Characterization of Interface State Density of Ni/p-GaN Structures by Capacitance/Conductance-Voltage-Frequency Measurements

For the frequency range of I kHz-lOMHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage （C-V） and conductance-frequency-voltage （G-f-V） measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance （Rs） on high-frequency （SMHz） capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the CHF-CLF capacitance and the conductance method are 2 ×1012 e V-1 cm-2 and 0.94 × 1012 eV-1 cm-2, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.

Irbesartan desmotropes:Solid-state characterization,thermodynamic study and dissolution properties

Irbesartan (IBS) is a tetrazole derivative and antihypertensive drug that has two interconvertible structures, 1H- and 2H-tautomers. The difference between them lies in the protonation of the tetrazole ring. In the solid-state, both tautomers can be isolated as crystal forms A (1H-tautomer) and B (2H-tautomer). Studies have reported that IBS is a polymorphic system and its forms A and B are related monotropically. These reports indicate form B as the most stable and less soluble form. Therefore, the goal of this contribution is to demonstrate through a complete solid-state characterization, thermodynamic study and dissolution properties that the IBS forms are desmotropes that are not related monotropically. However, the intention is also to call attention to the importance of conducting strict chemical and in solid-state quality controls on the IBS raw materials. Hence, powder X-ray diffraction (PXRD) and Raman spectroscopy (RS) at ambient and non-ambient conditions, differential scanning calorimetry (DSC), hot stage microscopy (HSM), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) techniques were applied. Furthermore, intrinsic dissolution rate (IDR) and structural stability studies at 98% relative humidity (RH), 25℃ and 40 ℃ were conducted as well. The results show that in fact, form A is approximately four-fold more soluble than form B. In addition, both IBS forms are stable at ambient conditions. Nevertheless, structural and/or chemical instability was observed in form B at 40℃ and 98% RH. IBS has been confirmed as a desmotropic system rather than a polymorphic one. Consequently, forms A and B are not related monotropically.

Novel Protease from Aspergillus tamarii URM4634: Production and Characterization Using Inexpensive Agroindustrial Substrates by Solid-State Fermentation

This study reports the protease production from Aspergillus tamarii using agroindustrial residues as substrate for solid-state fermentation (SSF) and biochemical characterization. The highest protease production was obtained using wheat bran as substrate at 72 h fermentation with maximum proteolytic activity of 401.42 U/mL, collagenase of 243.0 U/mL and keratinase of 19.1 U/mL. The protease exhibited KM = 18.7 mg/mL and Vmax = 28.5 mg/mL/min. The optimal pH was 8.0 and stable in a wide pH range (5.0 - 11.0) during 24 h. The optimum temperature was 40°C. The proteolytic activity was inhibited by Cu2+ (33.98%) and Hg2+ (22.69%). The enzyme was also inhibited by PMSF (65.11%), indicating that is a Serine Protease. These properties suggest that alkaline protease from A. tamarii URM4634 is suitable for application in food industries and leather processing. Additionally, the present findings opened new vistas in the utilization of wheat bran and other effective agroindustrial wastes as substrates for SSF.

Preliminary Synthesis and Characterization of Mesoporous Nanocrystalline Zirconia

A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ angle and their nitrogenadsorption/desorption isotherms are typical of type IV with H1 hysteresis loops. The pore structureimaged by TEM can be described as wormhole domains. The tetragonal zirconia nanocrystals are uniformin size (around 1.5 nm) and their mesopores focus on around 4.6 nm. The zirconia nanocrystal growthis tentatively postulated to be the result of an aggregation mechanism. This study also revealsthat the PEO surfactants can interact with the Zr-O-Zr framework to reinforce the thermal stabilityof zirconia. The ratio of NaOH to ZrOCl_2, crystallization and calcination temperature play animportant role in the synthesis of mesoporous nano-zirconia.

In-situ Characterization of Non-aqueous Nano-dispersion Systems by Freeze-etching TEM and Comparative Study with Laser Scattering Method

In-situ characterization of non-aqueous nano-dispersion systems（NANDS） by freeze-etching transmission electron microscope（FETEM） was reported.To improve just-for-once successive rate of specimen preparation and get good characterization results,an improving specimen preparation method of freezing etching was developed.Size,distribution and morphology of NANDS were directly visualized.Some information of particle dispersion feature and particle density can also be obtained.Reproductivity of the FETEM characterization is excellent.Comparing with laser scattering method,which is liable to give positive error especially for small size particle anchoring disperser,FETEM characterization can give more accurate measurement of particle size.Moreover,FETEM can give dispersion feature of nanoparticle in non-aqueous medium.

Fermentative Production of Mycelial Chitosan from Zygomycetes: Media Optimization and Physico-Chemical Characterization

The present study focused on production of mycelial chitosan from fungal mycelium by submerged fermentation with ecologically more balanced process. Different fungal strains were screened and Absidia butleri NCIM 977 was found to produce the highest mycelial chitosan. The one-factor-at-a-time method was adopted to investigate the effect of batch time, environmental factors (i.e. initial pH and temperature) and medium components (i.e. carbon and nitrogen) on the yield of mycelial chitosan. Among these variables, the optimal condition to increase in yield of mycelial chitosan was found to be batch time (72 h), pH (5.5), temperature (30°C), carbon source (glucose) and nitrogen source (tryptone and yeast extract). Subsequently, a three-level Box– Behnken factorial design was employed combining with response surface methodology (RSM) to maximise yield of mycelial chitosan by determining optimal concentrations and investigating the interactive effects of the most significant media components (i.e. carbon and nitrogen sources). The optimum value of parameters obtained through RSM was glucose (1.58%), tryptone (1.61%) and yeast extract (1.11%). There was an increase in mycelial chitosan yield after media optimization by one-factor-at-a-time and statistical analysis from 683 mg/L to 1 g/L. Mycelial chitosan was characterized for total glucosamine content (80.68%), degree of deacetylation (DD) (79.89%), molecular weight (8.07 × 104 Da) and, viscosity (73.22 ml/g). The results of this study demonstrated that fungi are promising alternative sources of chitosan with high DD and high purity.

基于改进Kruskal-Wallis检验的低压开关电器状态表征参数选择

由于状态数据的多属性、高维度和大数据量,以及特征参数难以满足正态性和方差齐性检验的事实,低压开关电器的状态表征参数难于选择。针对该问题,基于非参数单体多状态样本的分组状态间秩差异性,以及特征参数Kruskal-Wallis(KW)检验统计量的计算规则和变化趋势,研究论证了单体样本特征参数表征显著性鉴别机理。同时,基于状态序列斜率变化增量和子序列变异增量,提出样本状态时序分类算法,并将该算法与参数鉴别机理相结合,形成单体多状态样本改进KW检验理论。最后,基于改进理论提出低压开关电器状态表征参数选择新方法。以交流接触器为例进行验证,结果表明该文方法适用于具有非线性、非平稳、动态随机分布等特点的低压开关电器状态表征参数选择。实例证明,基于该方法获得状态表征曲线的拟合优度可达0.91,状态划分显著性P值可达8.42848×10–266,表征与分类精度较参数选择前及同类方法提升明显,为下一步研究低压开关电器状态的精确划分与识别奠定了理论基础。

基于孪生神经网络的楔形环连接结构预紧状态辨识

楔形环连接结构由于其连接简单可靠、同时兼具节省空间及减重的优势,常被应用于鱼雷、航天飞行器等武器装备。针对楔形环连接结构预紧状态辨识方面存在的机理模型复杂、样本量小且类别不平衡的问题,提出了一种基于孪生神经网络模型的预紧状态辨识方法。为提高模型训练效率和效果,首先利用时频处理技术进行孪生神经网络模型特征增强,基于增强特征建立了3层孪生神经网络分类模型,实现楔形环预紧状态宏观分类。同时,为指导楔形环精密装配,通过特征可视化技术,深入分析了孪生神经网络训练过程特征聚类效果,并基于二维特征建立了预紧状态定量表征模型,引入目标状态聚类中心与接受域参量,用于实现楔形环连接结构预紧状态定量评估。通过试验验证了所提方法的有效性,该方法可为楔形环连接结构定量辨识提供新的技术途径和思路,具有一定工程应用价值。

“混合学街”的样态表征、实践价值与政策贡献

“混合学街”是温州市第二职业中等专业学校首创的职业院校混合所有制办学新模式,其样态表征体现在三个方面:基础在“混合”、关键在“治理”、核心在“育人”。对“混合学街”的实践探索深化了产教融合、优化了产教资源的合理配置、推动了职业学校高质量发展,不仅为混合所有制办学政策创新提供了典型模式、路径方法,也为混合所有制办学政策创新增添了勇气信心。

白虎汤纳米相态相关研究进展

中药汤剂包含真溶液、纳米相态、乳浊液和混悬液,是一种复杂的多分散相体系。中药汤剂的有效成分主要存在于纳米相态中,与中药汤剂相比,中药纳米相态具有溶解性强、稳定性高、药效佳等特点。随着研究的深入,有学者提出汤剂中的纳米粒子可能起着增溶与靶向递送的作用。白虎汤是清热类经典方剂之一,被称为“寒剂祖方”,由石膏、知母、炙甘草、粳米四味药材配伍而成,用于治疗阳明经证或气分热盛证,现代临床上应用广泛。白虎汤纳米相态可能包裹药物有效成分,实现药物的靶向性治疗。研究发现白虎汤药液的纳米相态中主要药效成分的含量明显高于药液中的其他相态,纳米相态对汤剂中主要解热成分芒果苷、新芒果苷、钙离子、甘草酸和甘草次酸起到了增溶作用,纳米相态是白虎汤发挥解热作用的关键组分。本文从白虎汤纳米相态的形成理论、物质基础、分子表征、药理作用等方面进行综述,为深入探究白虎汤的作用机制、创制纳米相态制剂提供思路,为推动纳米技术在中药方剂创新中的应用提供参考。

基于多特征增强融合的交流接触器状态表征

准确掌握交流接触器的运行状态是实现交流接触器智能化的基础,为此提出了一种基于多特征增强融合的状态表征方法。首先针对交流接触器特征参数非线性、非平稳、随机变化、趋势性不明显但符合一定统计特性的特点,利用Wasserstein概率距离进行特征变换得到趋势性较强的初态特征;然后以多属性初态特征参数为驱动,考虑参数间强耦合的特点,利用自编码器神经网络进行特征压缩提取,剔除冗余信息,保留有用信息;在此基础上,以压缩提取特征为输入,通过自组织映射神经网络来实现多维特征的竞争性融合输出,得到交流接触器运行状态的综合健康指标,实现交流接触器状态的定量表征。最后,结合实测数据验证了所提方法的有效性,并与其他2种方法相比较,结果表明:所提方法得到的健康指标趋势性、单调性和鲁棒性相比其他2种方法分别至少提高了4%、24%和5%,研究可为下一步研究交流接触器的精准控制和智能化提供参考。

电池储能系统状态估计综述

为了提高多场景应用的技术经济性,本文对电池储能系统状态估计进行了综述。首先,分析了电池性能衰减的机理,介绍了目前常用的物理建模和数据建模方法,进而对荷电状态(state of charge,SOC)和健康状态(state of health,SOH)进行了定义与关联性分析,并对电池及其系统的状态估计方法进行了汇总;其次,为了获取更多精确的电池运行数据,重点介绍了能够刻画电池内部演化机理的原位/非原位表征技术,进而分析了嵌入式电池管理系统(battery management system,BMS)实际应用的主流开发路线;第三,提出了基于联邦学习的电池储能系统状态估计方法,基于轻量化模型在本地进行电池储能系统SOC的估计以保证控制实时性,基于大数据驱动策略在云中心进行其SOH估计以保证容量可信度,由此实现云边的交互与协同;最后,对电池储能系统未来可能的发展方向和研究重点进行了预测。研究结果表明:活性锂损失是锂离子电池容量衰退的主要原因,高温、低温、过充放等滥用也会加速电池性能衰减;数据驱动在电池系统级建模与状态评估方面具有较大优势;利用原位/非原位表征技术可以获取更多的电池内部状态数据,基于FPGA的BMS轻量化建模更易实现,基于联邦学习的状态评估方法能够提高电池储能系统的智慧化运维水平。

河北武安地区黏土岩的稀土元素赋存状态

黏土岩是稀土元素的主要赋存岩石之一,具有非常大的资源潜力。目前,由于其稀土元素赋存状态不明确,黏土岩稀土矿产开发利用受限。本文选取河北武安市暴庄地区富稀土黏土岩,利用岩矿鉴定、矿物自动定量系统(AMICS)、X射线衍射仪(XRD)等方法对矿石的岩石学特征进行分析,同步利用激光剥蚀-等离子质谱(LA-ICP-MS)微区原位分析、高岭石黏粒提取、化学分步提取、飞行时间二次离子质谱仪(TOF-SIMS)及密度函数理论(DFT)计算等技术手段,从矿物学、地球化学及结构学等多尺度多角度对样品中的稀土元素赋存状态进行科学研究。结果表明,该地区黏土岩的主要组成矿物为高岭石(88.19%),盐类浸出试验结果表明离子型稀土仅占2.67%,而稀土独立矿物仅含0.04%的褐帘石,证明稀土元素以离子态及独立矿物型存在的占比较少,而稀土元素与高岭石之间的强相关性可以推测多数稀土元素或以超微细粒稀土矿物形式夹杂于高岭石颗粒之间,或以类质同象替代存在于高岭石晶格内。

Local characterization of the polarization state of 3D electromagnetic fields:an alternative approach

A precise knowledge of the polarization state of light is crucial in technologies that involve the generation and application of structured light fields. The implementation of efficient methods to determine and characterize polarization states is mandatory;more importantly, these structured light fields must be at any spatial location at a low expense. Here, we introduce a new characterization method that relies on a rather convenient description of electric fields without neglecting their 3D nature. This method is particularly suitable for highly focused fields,which exhibit important polarization contributions along their propagation direction in the neighborhood of the focal region;i.e., the contributions out of the planes transverse to the optical axis, conventionally used to specify the polarization state of these fields. As shown, the method allows the extraction of information about the three field components at relatively low computational and experimental costs. Furthermore, it also allows characterization of the polarization state of a field in a rather simple manner. To check the feasibility and reliability of the method, we determined both analytically and experimentally the local polarization states for a series of benchmark input fields with it, finding excellent agreement between the theory and experiment.

FORWARD GATED-DIODE R-G CURRENT METHOD: A SIMPLE NOVEL TECHNIQUE FOR CHARACTERIZING LATERAL LIGHTLY DOPING REGION OF LDD MOSFET's

This paper presents a simple novel technique-forward gated-diode R-G current method-to determine the lateral lightly-doped source/drain (S/D) region interface state density and effective surface doping concentration of the lightly-doped drain (LDD) N- MOSFET's simultaneously. One interesting result of the numerical analysis is the direct characterization of the interface state density and characteristic gate voltage values corresponding to LDD effective surface doping concentration. It is observed that the S/D N- surface doping concentration and corresponding region's interface state density are R-G current peak position and amplitude dependent, respectively. It is convincible that the proposed method is well suitable for the characterization of deep sub-micron MOSFET's in the current ULSI technology.

PREDICTION OF THE PHASE BEHAVIOR OF GAS CONDENSATES USING PATEL-TEJA EQUATION OF STATE AND GAMMA DISTRIBUTION FUNCTION

The three-parameter Petal-Teja equation of state coupled with a characterization proceduref0r C7+-fraction based on gamma distribution function was employed to predict the phase behaviorof eight gas condensates.The lumping of the subdivided single carbon number（SCN）hydrocarbons inthe plus-fraction and the choice of empirical correlations for calculating the critical properties andacentric factor of SCN hydrocarbons were discussed.

Unrelaxed State in Epitaxial Heterostructures Based on Lead Selenide

The work deals with the epitaxial PbSe layers grown on the KCl substrates by the method of “hot-wall” molecular epitaxy over the range of layer thicknesses of 20 - 2000 nm. Special emphasis is put on the values of elastic deformations that could be generated and frozen in epitaxial layers with the aim of influencing their energy spectra and optical properties. The maximum deformation at layers tension made up 57% of the initial mismatch between the layer and the substrate (ε = Δa/a = 0.015). In such a solid-state structure effective “negative” pressure is realized, which is justified by increase in the tangential lattice constant and the forbidden gap width. This width correlates with the tangential lattice constant (deformation) and corresponds to certain values of definite frequencies of direct electron transitions across the forbidden gap.

Purification and Characterisation of a Coffee Pulp Tannase Produced by Penicillium verrucosum

Tannase was extracted from a new fungal strain Penicillium verrucosum using coffee pulp as a substrate by solid state fermentation. The extracellular tannase was purified using Sephadex G-100 to 86.02 folds with 34.3% yield and a single band corresponding to 81 kDa was observed in SDS-PAGE. Tannase was immobilized on alginate by entrapment method. The graphical analysis of the effect of the substrate concentration on the tannase activity yielded a Km of 48.88 mM and a Vmax of 169.49 U/mL. The optimum temperature and pH of the enzyme were 30 ℃ and pH 5. The thermal stability, as well as stability over a wide range ofpH, was significantly improved by the immobilization process. The activity was enhanced by Mg^2＋ （23.5%） and K^＋ （5.3%）, whereas Zn^2＋, Cu^2＋, Ca^2＋, NH^4＋ and Hg^2＋ inhibited tannase activity. Maximum substrate bioconversion （58.94%） from tannic acid to gallic acid and tea cream solubilisation （32.82%） was achieved using immobilized tannase. The extracellular tannase produced by P. verrucosum showed distinctive characteristics such as monomeric structure and activation by Mg^2＋, suggesting a new kind of fungal tannase with biotechnological potential.

Recent Industrial Developments of Marine Composites Limit States and Design Approaches on Strength

To further exploit the potential of marine composites applications in building ship hulls,offshore structures,and marine equipment and components,design approaches should be improved,facing the challenge of a more comprehensive and explicit assessment of appropriately defined limit states.The structure ultimate/limit conditions shall be verified in principle within the whole structural domain and throughout the ship service life.What above calls for extended and reliable materials characterization on the one hand and for accurate and wide-ranging procedures in structural analyses.This paper presents an overview of recent industrial developments of marine composites limit states assessments and design approaches,as available in open literature,focusing on pleasure crafts and yachts as well as navy ships and thus showing a starting point to fill the gap in this respect.After a general introduction about composites characterization techniques,current design practice and rule requirements are briefly summarized.Both inter-ply and intra-ply failure modes and corresponding limit states are then presented along with recently proposed assessment approaches.Three-dimensional aspects in failure modes and manufacturing methods have been identified as the main factors influencing marine composite robustness.Literature review highlighted also fire resistance and hybrid joining techniques as significant issues in the use of marine composites.