Synthesis of mordenite by solvent-free method and its application in the dimethyl ether carbonylation reaction

Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sites were systematically investigated.The characterization results showed that with the increase of Si/Al ratio in the feedstock,part of silicon species fail to enter the skeleton and the specific surface area and pore volume of the samples decreased.The amount of weak acid and medium strong acid decreased alongside with the increasing Si/Al ratio,and the amount of strong acid slightly increased.The Al atoms preferentially enter the strong acid sites in the 8 member ring(MR)channel during the crystallization process.The high Si/Al ratio sample had more acid sites located in the 8 MR channel,leading to more active sites for carbonylation reaction and higher catalytic performance.Appropriately increasing the Si/Al ratio was beneficial for the improvement of carbonylation reaction activity over the mordenite(MOR)catalyst.

结合交并比损失的孪生网络目标跟踪算法研究

SiamRPN算法采用Ln范数损失训练边界框预测,未考虑预测框与真值框间交并比(inersection over union,IoU)的关系,导致准确性不足。针对该问题,提出一种结合IoU损失的SiamRPN目标跟踪改进算法。设计了IoU-smooth L1范数联合优化模块,对候选正样本进行IoU损失与smooth L1范数损失的联合优化;依据回归预测结果,用预测框与真值框的IoU作为权重对正样本进行加权分类预测,增加正样本间的区分度,同时确保分类预测与回归预测的关联性。对比实验结果表明:本文所提改进算法能有效提升跟踪性能。

Understanding pitting corrosion behavior of AZ91 alloy and its MAO coating in 3.5%NaCl solution by cyclic potentiodynamic polarization

The pitting corrosion behavior of AZ91 alloy before and after micro-oxidation treatment in 3.5%Na Cl solution was investigated by cyclic potentiodynamic polarization(CPDP)and optical and SEM observations of corroded surfaces at different polarization potentials.The CPDP results show that both the alloy and the MAO-coated alloy suffer from pitting corrosion and it is difficult for pits to stop growth once the pits initiates.It is revealed that the air-formed Mg O film on AZ91 alloy,the MAO coating along with corrosion products(mainly Mg(OH))formed during CPDP can significantly influence the kinetics of the redox reactions of Mg,and further influence the propagation behavior of pitting corrosion.The optical and SEM images show that the corrosion products on AZ91 alloy are dense and protective but on the MAO-coated corrosion products are very loose.Such observations support the analyses of CPDP results that pits on AZ91 alloy spread to the width whereas pits on MAO-coated alloy propagate to the depth.Overall,pitting corrosion on the MAO-coated alloy can be very severe once the coating ruptures and post-treatments are necessary to provide a promising corrosion protection for the Mg alloys.

Nitrogen removal characteristics of heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis C16

Alcaligenes faecalis C16 was found to have the ability to heterotrophically nitrify and aerobically denitrify. In order to further understand its nitrogen removal ability and mechanism, the growth and ammonium removal response were investigated at different C/N ratios and ammonium concentrations in the medium with citrate and acetate as carbon source separately. Furthermore, experiments of nitrogen sources, production of nitrogen gas and enzyme assay were conducted. Results show that the bacterium converts NH+4-N and produces NH2 OH during the growing phase and nitrite accumulation is its distinct metabolic feature. A. faecalis C16 is able to tolerate not only high ammonium concentration but also high C/N ratio, and the ammonium tolerance is associated with carbon source and C/N ratio. The nitrogen balance under different conditions shows that approximately28%–45% of the initial ammonium is assimilated into the cells, 44%–60% is denitrified and several percent is converted to nitrification products. A. faecalis C16 cannot utilize hydroxylamine, nitrite or nitrate as the sole nitrogen source for growth. However, nitrate can be used when ammonium is simultaneously present in the medium. A possible pathway for nitrogen removal by C16 is suggested. The preliminary enzyme assay provides more evidence for this nitrogen removal pathway.

Understanding the effects of excimer laser treatment on corrosion behavior of biodegradable Mg-1Ca alloy in simulated body fluid

In this study,a KrF excimer laser was used to modify the biodegradable Mg-1Ca alloy and the time-evolution degradation behavior of the alloy before and after laser treatment was investigated in simulated body fluid(SBF)solution using immersion tests and electrochemical impedance spectroscopy(EIS).A 5μm melted layer with a homogeneous microstructure and an MgO film on the surface were achieved by laser radiation.Corrosion observations(hydrogen evolution,morphology and corrosion products)and EIS results revealed an improvement of corrosion resistance after laser treatment for 48 h.It was found a two-layer structure developed after 2 h immersion on both the untreated and laser-treated alloys,but the sequence of forming the two layers was opposite and greatly influenced by the laser-treated layer.The time-evolution corrosion processes on the untreated and laser-treated alloys were discussed,providing a better understanding of corrosion behavior of biodegradable Mg alloys modified by excimer laser.

Screening of Fermentation Starters for Organic Fertilizer Composted from Chicken Manure

In order to find fermentation starters that can promote rapid and effective composting of chicken manure,shorten the fermentation period,and improve the compost quality,fermentation starters with different microbial combination ratios(C1,C2,C3,C4 and C5) were designed and fermentation experiment was carried out on these five fermentation starters,commercially available organic fertilizer starter(SS),and chicken manure without inoculating fermentation starter. In the process of the fermentation,the changes in the fermentation temperature,water content and pH value were monitored; the effects of organic manure on the germination rate and growth of rapeseed seeds were measured;viable count,water content,and pH value of prepared fermentation starters were measured; main indicators( organic matter,nitrogen,phosphorus,and potassium) of organic fertilizer generated from fermentation were measured. From the indicators,the formula C3 and C4 were better,in the beginning of fermentation,the temperature rose rapidly,and it reached 40 ℃ in the second day; the water content dropped to below 35% in the 18 th day; the pH value underwent the process of declining-rising-stable,and the overall value showed slight rise,but the change was not great( 0-0. 5). C3 and C4 fermentation products had better effects on the germination and growth of rapeseeds. The germination rate of the rapeseed seeds was 100% and 97. 5% and the bud length was 15. 94 mm and 14. 57 mm,respectively,and the root length was45. 97 mm and 39. 44 mm,respectively. The content of organic matter in fermented organic manure was 86. 62% and 85. 17% respectively,and the total content of nitrogen,phosphorus and potassium was 8. 85% and 8. 22% respectively,and the pH was 7. 5 and 8. 0 respectively.All of these complied with the industry standard NY525-2012( organic matter ≥ 45%,and nitrogen,phosphorus,and potassium ≥ 5%,pH 5. 5-8. 5). The fermentation of fresh chicken manure was completed within 20 days,conforming to the requirements of large-scale organic fertilizer production factory for composting chicken manure into organic fertilizer.

Multi-timescale Modeling and Dynamic Stability Analysis for Sustainable Microgrids:State-of-the-art and Perspectives

The increasing trend for integrating renewable energy sources into the grid to achieve a cleaner energy system is one of the main reasons for the development of sustainable microgrid(MG)technologies.As typical power-electronized power systems,MGs make extensive use of power electronics converters,which are highly controllable and flexible but lead to a profound impact on the dynamic performance of the whole system.Compared with traditional large-capacity power systems,MGs are less resistant to perturbations,and various dynamic variables are coupled with each other on multiple timescales,resulting in a more complex system instability mechanism.To meet the technical and economic challenges,such as active and reactive power-sharing,voltage,and frequency deviations,and imbalances between power supply and demand,the concept of hierarchical control has been introduced into MGs,allowing systems to control and manage the high capacity of renewable energy sources and loads.However,as the capacity and scale of the MG system increase,along with a multi-timescale control loop design,the multi-timescale interactions in the system may become more significant,posing a serious threat to its safe and stable operation.To investigate the multi-timescale behaviors and instability mechanisms under dynamic inter-actions for AC MGs,existing coordinated control strategies are discussed,and the dynamic stability of the system is defined and classified in this paper.Then,the modeling and assessment methods for the stability analysis of multi-timescale systems are also summarized.Finally,an outlook and discussion of future research directions for AC MGs are also presented.

Portable fluorescence instrument for detecting membrane integrity in membrane bioreactor (MBR)

This study proposed the design, fabrication, and assembly of membrane integrity detection instruments in membrane bioreactors (MBR) based on fluorescence spectroscopy. Based on the PARAFAC model, we found that the peak at 280/335 nm strengthened after membrane breakage. The peak at 340/430 nm reflected the sludge concentration in the MBR and reduced the influence of internal filtration effects on detection. Therefore, we determined that the dual-LED light source excitation detection system can detect tryptophan-like substances at 280 nm (T-peak) and humic acid at 340 nm (C-peak). T-peak was identified as the core index indicating membrane integrity. Moreover, the C-peak is the reference indicator factor for a sensitive response to changes in the sludge concentration. The portable fluorescence instrument exhibited high sensitivity and good feedback accuracy compared to particle counting and turbidity detection, where the log reduction value was greater than 3.5. This overcomes the disadvantage of false alarms in particle counters and is not affected by the position of the pump system. This portable instrument provides a flexible and highly sensitive method for the assessment of industrial membrane integrity.

Designable heteronanocrystals via interface redox reaction

The synergistic interaction of different components in heteronanocrystals induces interfacial phenomena and novel functionalities.Nonetheless,effective technologies to design and fabricate heteronanocrystals with materials on demand are still missing.Rich heterostructures in a copper patina are known to form at room temperature and under atmospheric pressure.The redox process of copper tarnish inspired the discovery of a simple strategy to achieve heteronanocrystals that contained elements from group 3-11 and group 14-16.The interface redox-induced method is self-regulating at ambient conditions and applicable for metal,semiconductor,and dielectric materials.The enhanced interface bonding endows the heteronanocrystals with outstanding stability and catalytic performance,while the modular approach enables the design and fabrication of heteronanocrystals with intended materials to meet different purposes.

社会空间视角下监狱人民警察与罪犯的关系研究

社会空间理论为研究监狱人民警察与罪犯的关系(警囚关系)提供了更新的视角、更广的视野、更大的维度。基于社会空间视角,能够更好地把握警囚关系在新的历史时期表现出的内涵属性,实现对警囚关系的结构性分析和解读。以社会空间理论为指引,通过系统深入地分析警囚关系的内涵要义、主要特征和影响要素,揭示出当前警囚关系的现状,尤其是负性警囚关系的具体呈现,以此为基础,提出从树立法治理念、完善制度规则、健全执法管理、优化数字治理、提升民警素质、构建支持网络等方面构建良性警囚关系的对策措施,全方位防范负性警囚关系的不良影响,努力使良性警囚关系占据主导地位,以更好地实现监狱价值使命。

基于卷积神经网络的无网格形函数影响域优化研究

在无网格法中,离散节点之间的相互联系由节点形函数影响域的大小确定,因此形函数影响域的大小对无网格法的计算精度有着直接和重要的影响.但由于无网格形函数的形式较为复杂,目前形函数影响域大小的选择仍然缺乏系统的理论依据,通常在实际计算中仍凭借经验进行选取,难以保证计算精度.卷积神经网络是一类机器学习方法,其感受野与无网格形函数的影响域具有内在相似性,因此在形函数影响域选择方面有很好的适用性.基于该特性,论文通过引入卷积神经网络对无网格形函数的影响域进行了优化选择.首先,针对感受野和影响域的匹配关系,分析了卷积神经网络的结构设计和超参数选择,提出了一种无网格法内禀卷积神经网络结构的设计方法;然后依托该网络结构设计方法,建立了对无网格形函数影响域和数值解分别优化或同时优化的卷积神经网络.文中通过算例系统验证了所提无网格法内禀卷积神经网络对形函数影响域选择和计算结果的优化效应.

Molecular mechanism of endocrine-disruptive effects induced by Bisphenol A:The role of transmembrane G-protein estrogen receptor 1 and integrin αvβ3

Bisphenol A(BPA) is one of the highest volume industrial products worldwide and has been widely used to make various products as the intermediates of polycarbonate plastics and epoxy resins.Inevitably, general population has been widely exposed to BPA due to extensive use of BPAcontaining products. BPA has similar chemical structure with the natural estrogen and has been shown to induce a variety of estrogen-like endocrine effects on organism in vivo or in vitro. High doses of BPA tend to act as antagonist of estrogen receptors(ERs) by directly regulating the genomic transcription. However, BPA at environmentally relevant low-dose always disrupt the biological function via a non-genomic manner mediated by membrane receptors, rather than ERs. Although some studies had investigated the non-genomic effects of low-dose BPA, the exact molecular mechanism still remains unclear. Recently, we found that membrane G protein-coupled estrogen receptor 1 and integrin αvβ3 and its relative signal pathways participate in the induction of male germ cell proliferation and thyroid transcription disruption by the low-dose BPA. A profound understanding for the mechanism of action of the environmentally relevant BPA exposure not only contributes to objectively evaluate and predict the potential influence to human health, but also provides theoretical basis and methodological support for assessing health effects trigged by other estrogen-like environmental endocrine disruptors. Based mainly on our recent findings, this review outlines the research progress of molecular mechanism on endocrine disrupting effects of environmental low-dose BPA, existing problems and some consideration for future studies.

An isolation strategy to anchor atomic Ni or Co cocatalysts on TiO_(2)(A)for photocatalytic hydrogen production

TiO_(2) has been considered as an ideal photocatalyst for water splitting.However,narrow light absorbance,low charge separation efficiency,and rare surface active sites lead to the low photocatalytic efficiency of TiO_(2).Although extensive research attempted to improve the situation,there is still lack of method for constructing high active and noble-metal-free TiO_(2) photocatalyst for H_(2) evolution reactions(HER).In this work,we loaded single atomic(SA)Ni(or Co)on the surface of anatase TiO_(2)(TiO_(2)(A))nanosheets by an isolation strategy.Ethylene diamine tetraacetic acid and ethylene glycol(EDTA-EG)compounds were used to chelate metal ions in solution and form carbon quantum dots in the following thermal treatment to isolate the metal ions on surface of TiO_(2)(A).The prepared Ni SA/TiO_(2)(A)catalyst owned a“skin wrapped body”structure with in-situ formed twodimensional(2D)heterojunction facilitating the fast electron transfer.As a result,the Ni SA/TiO_(2)(A)catalyst showed a high H_(2) evolution rate of 2,900μmol·g−1·h−1.This work provides an isolation strategy for constructing promising single-atom metal catalyst for photocatalysis and beyond.

Reconsidering sex differences during place learning in tungara frogs

In tungara frogs, female mate choice requires remembering the location and/or calls of preferred males who advertise from fixed positions within a breeding pond. A previous study found that, when solving a place discrimination task in the laboratory, female tCingara frogs were able to learn a visual cue to solve the task, whereas males were not. In that task, male performance appeared to be inhibited, in part, by their attempt to use egocentric cues. We tested whether the sex difference in place learning previously reported would generalize to other training parameters with different cues available by eliminating the potential to use egocentric cues and increasing the number of trials per day. As before, frogs were given a choice between a red or yellow door, one of which led to shelters and return to their home cage. In the current testing conditions, we detected a preference for the red door;thus, we only considered frogs rewarded to the yellow door. Training was associated with an in crease in correct choices and an in creased preference for the yellow door. However, there was no evide nee for a sex d iff ere nee in learni ng. In summary, un der the curre nt training conditions, we fou nd that the appare nt female advantage in place learning was no Ion ger evide nt. Future studies that in vestigate sex d iff ere nces in cue pref ere nee and/or ability to switch among cues will further illuminate the conditions under which sex differences in learning are manifest in tungara frogs.

监狱空间治理研究

空间理论为监狱治理提供了全新的视角。在空间理论视角下,监狱作为惩罚与改造罪犯的特定空间,与社区矫正的空间概念有着较大差异,呈现出物质空间封闭性、社会空间开放性、文化空间多元性以及监狱空间的整体性的特点。由于当下监狱空间治理中存在空间意识不强、空间错位、边界不清等问题,导致了监狱在安全、执法、改造等领域遇到诸多现实困境和治理难题。监狱治理需要积极借鉴空间理论,围绕物质空间、社会空间、文化空间三个基本面向,聚焦监狱空间治理要素,理清监狱内部空间的边界,建设警察文化和新生文化,不断优化完善监狱治理结构,提升治理质效,更好地履行监狱职能。