Effects of anions on the structural regulation of Zn‑salen‑modified metal‑organic cage

By virtue of a 3∶1 complementary coordination strategy,a chiral heteroleptic metal-organic cage that con-tains divergent functional units,Pd‑R(Zn),was precisely constructed via self-assembly of monodentate variational Zn-salen ligands RZn and NADH(reduced nicotinamide adenine dinucleotide)mimic modified tridentate ligands with square-planar Pd ions.UV-Vis and luminescence spectra experiments reveal that different anions could selec-tively interact with different sites of Zn-salen modified metal-organic cages to achieve the structural regulation of cage compound,by using the differentiated host-guest electrostatic interactions of counter ions with metal-organic hosts.Compared to other anions,the presence of chloride ions caused the most significant fluorescence emission enhancement of Pd‑R(Zn),meanwhile,the UV-Vis absorption band attributed to the salen aromatic backbone showed an absorption decrease,and the metal-to-ligand induced peak displayed a blue shift effect.Circular dichro-ism and ^(1)H NMR spectra further demonstrate that the introduction of chloride anions is beneficial to keeping a more rigid scaffold.

Tar formation characteristic of integrated process of coal pyrolysis with dry reforming of low carbon alkane over Ni/La_(2)O_(3)-ZrO_(2)

Coal pyrolysis integrated with dry reforming of low-carbon alkane(CP-DRA)is an effective way to improve tar yield.Ni/La_(2)O_(3)-ZrO_(2) with a La/Zr ratio of 4 was a good catalyst for DRA to inhibit carbon deposition and obtain high tar yield in CP-DRA.In this study,the fraction distribution and component of tars from CP-DRA and coal pyrolysis in N_(2) atmosphere(CP-N_(2))were characterized by using several methods to understand the effect of DRA on coal pyrolysis.The isotope trace method was also used to discuss the role of low-carbon alkane in CP-DRA.The results showed that the tar from CP-N_(2)is mainly composed of aliphatic compounds with more C_(al),H_(al) and CH+CH_(2),and the tar from CP-DRA contains more Car,Har,and CH_(3),and has lower weight-average molecular weight and more light tar content than CP-N_(2).A small amount of C_(2)H_(6) addition in CP-DRA will raise the ratio of H_(β) and CH+CH_(2).Electron paramagnetic resonance(EPR)analysis shows that the tar from CP-DRA has a higher radical concentration while the corresponding char has a lower radical concentration.The isotope trace experiment showed that alkanes provide·H,·CH_(3),etc.to stabilize the radicals from coal pyrolysis and result in more alkyl aromatic compounds during CP-DRA.

Structures and magnetism of dinuclear Co complexes based on imine derivatives

This study presents the synthesis of three dinuclear cobalt complexes based on three imine derivatives:bis-[4-(2-pyridylmethyleneamino)-phenyl]thioether(L1),bis-[4-(2-pyridylmethyleneamino)-phenyl]ether(L2),and bis-[4-(2-pyridylmethyleneamino)-phenyl]methane(L3).Single-crystal X-ray diffraction analysis reveals that the complexes[Co_(2)(L1)3](ClO_(4))4·2CH_(3)CN(1),[Co_(2)(L2)3](ClO_(4))4·2CH_(3)OH(2),and[Co_(2)(L3)3](ClO_(4))4·2CH_(3)OH(3)all exhibit a dinuclear structure.Magnetic test results show that complex 3 exhibited irreversible SCO behavior induced by loss of solvent at 300 K,with the average Co-N bond length increasing from 0.2139(3)to 0.2153(3)nm.Meanwhile,the desolvated complex 3 exhibited paramagnetic behavior similar to that of complexes 1 and 2.Variable-temperature UV-Vis spectroscopic studies also indicate that complex 3 undergoes a solvent-loss-induced spin-state transition.CCDC:2347354,1(120 K);2347355,2(120 K);2347356,3(120 K);2347357,3(400 K).

Cryogenic springback of 2219-W aluminum alloy sheet through V-shaped bending

A V-shaped bending device was established to evaluate the effects of temperature and bending fillet radius on springback behavior of 2219-W aluminum alloy at cryogenic temperatures.The cryogenic springback mechanism was elucidated through mechanical analyses and numerical simulations.The results indicated that the springback angle at cryogenic temperatures was greater than that at room temperature.The springback angle increased further as the temperature returned to ambient conditions,attributed to the combined effects of the “dual enhancement effect” and thermal expansion.Notably,a critical fillet radius made the springback angle zero for 90° V-shaped bending.The critical fillet radius at cryogenic temperatures was smaller than that at room temperature,owing to the influence of temperature variations on the bending moment ratio between the forward bending section at the fillet and the reverse bending section of the straight arm.

Dynamic Characteristics of Irregular Ice Floes Based on Polyhedral Discrete Element Method

In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. This study introduces a polyhedral Discrete Element Method (DEM) tailored for polar ice, incorporating the Gilbert-Johnson-Keerthi (GJK) and Expanding Polytope Algorithm (EPA) for contact detection. This approach facilitates the simulation of the drift and collision processes of floating ice, effectively capturing its freezing and fragmentation. Subsequently, the stability and reli ability of this model are validated by uniaxial compression on level ice fields, focusing specifically on the influence of compression strength on deformation resistance. Additionally, clusters of ice floes nav igating through narrow channels are simulated. These studies have qualitatively assessed the effects of Floe Size Distribution (FSD), initial concentration, and circularity on their flow dynamics. The higher power-law exponent values in the FSD, increased circularity, and decreased concentration are each as sociated with accelerated flow in ice floe fields. The simulation results distinctly demonstrate the con siderable impact of sea ice geometry on the movement of clusters, offering valuable insights into the complexities of polar ice dynamics.

Visualizing Language and Aging From 2013-2022

Declining cognitive abilities can be a concomitant of advanced age.As language is closely associated with cognitive abilities,changes in language abilities can be an important marker of changes in cognitive abilities.The current study is to review cognitive studies of language and aging by first identifying and exploring the major clusters and pivotal articles and then detecting emerging trends.Data of 3,266 articles on language and aging from 2013 to 2022 were collected from the Web of Science Core Collection database.Adopting Document Co-citation Analysis,Freeman’s betweenness centrality metric(Freeman,2002)and Kleinberg’s burst detection algorithm(Kleinberg,2002),we explored major clusters,pivotal articles and emerging trends in this field.Cognition appears to be the most remarkable cluster.Bilingualism,speech production,listening effort,and reading comprehension are other major active clusters in a certain period.The most recent active cluster concerns the studies of Alzheimer’s disease.Articles serving as pivotal points concentrate on cognitive studies of the Framework for Understanding Effortful Listening(FUEL),the new Ease of Language Understanding model(EUL)and a hierarchical multi-representational generative framework of language comprehension.The progress in statistical methods,the relationship between language and cognitive impairment and the relationship between language abilities and cognition are the emerging trends.These emerging trends will provide some insights into how cognitive abilities influence language abilities in aging.

A Framework of LSTM Neural Network Model in Multi-Time Scale Real-Time Prediction of Ship Motions in Head Waves

Ship motions induced by waves have a significant impact on the efficiency and safety of offshore operations.Real-time prediction of ship motions in the next few seconds plays a crucial role in performing sensitive activities.However,the obvious memory effect of ship motion time series brings certain difficulty to rapid and accurate prediction.Therefore,a real-time framework based on the Long-Short Term Memory(LSTM)neural network model is proposed to predict ship motions in regular and irregular head waves.A 15000 TEU container ship model is employed to illustrate the proposed framework.The numerical implementation and the real-time ship motion prediction in irregular head waves corresponding to the different time scales are carried out based on the container ship model.The related experimental data were employed to verify the numerical simulation results.The results show that the proposed method is more robust than the classical extreme short-term prediction method based on potential flow theory in the prediction of nonlinear ship motions.

Cu-based heterojunction catalysts for electrocatalytic nitrate reduction to ammonia

Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they still face challenges pertaining of poor stability and low activity,which hinder their further application.Herein,we present a Cu_(2)O/Cu heterojunction catalyst supported on nitrogen-doped porous carbon for nitrate reduction.High resolution transmission electron microscopy(HRTEM)and X-ray Diffraction(XRD)results confirm the presence of Cu_(2)O/Cu heterojunctions,which serve as an active phase in catalysis.The nitrogen-doped porous carbon as a carrier not only enhances the catalyst’s stability,but also facilitates the exposure and dispersion of active sites.At-1.29 V(vs.RHE),the maximum production rate of ammonia reaches 8.8 mg/(mg·h)with a Faradaic efficiency of 92.8%.This study also elucidates the effect of Cu_(2)O-to-Cu ratio in the heterojunction on catalytic performance,thereby providing valuable insights for designing efficient nitrate reduction catalysts for ammonia production.

Embodied Meaning in Comprehending Abstract Chinese Counterfactuals

Embodied cognition theories propose that language comprehension triggers a sensorimotor system in the brain.However,most previous research has paid much attention to concrete and factual sentences,and little emphasis has been put on the research of abstract and counterfactual sentences.The primary challenges for embodied theories lie in elucidating the meanings of abstract and counterfactual sentences.The most prevalent explanation is that abstract and counterfactual sentences are grounded in the activation of a sensorimotor system,in exactly the same way as concrete and factual ones.The present research employed a dual-task experimental paradigm to investigate whether the embodied meaning is activated in comprehending action-related abstract Chinese counterfactual sentences through the presence or absence of action-sentence compatibility effect(ACE).Participants were instructed to read and listen to the action-related abstract Chinese factual or counterfactual sentences describing an abstract transfer word towards or away from them,and then move their fingers towards or away from them to press the buttons in the same direction as the motion cue of the transfer verb.The action-sentence compatibility effect was observed in both abstract factual and counterfactual sentences,in line with the embodied cognition theories,which indicated that the embodied meanings were activated in both action-related abstract factuals and counterfactuals.

Efficient Inverse Analysis for Solving a Coupled Conduction,Convection and Radiation Problem Involving Non⁃gray Participating Media

The presence of non-gray radiative properties in a reheating furnace’s medium that absorbs,emits,and involves non-gray creates more complex radiative heat transfer problems.Furthermore,it adds difficulty to solving the coupled conduction,convection,and radiation problem,leading to suboptimal efficiency that fails to meet real-time control demands.To overcome this difficulty,comparable gray radiative properties of non-gray media are proposed and estimated by solving an inverse problem.However,the required iteration numbers by using a least-squares method are too many and resulted in a very low inverse efficiency.It is necessary to present an efficient method for the equivalence.The Levenberg-Marquardt algorithm is utilized to solve the inverse problem of coupled heat transfer,and the gray-equivalent radiative characteristics are successfully recovered.It is our intention that the issue of low inverse efficiency,which has been observed when the least-squares method is employed,will be resolved.To enhance the performance of the Levenberg-Marquardt algorithm,a modification is implemented for determining the damping factor.Detailed investigations are also conducted to evaluate its accuracy,stability of convergence,efficiency,and robustness of the algorithm.Subsequently,a comparison is made between the results achieved using each method.

Structure and Vibrational Spectroscopy of 2-Methylallyl Alcohol

The intramolecular O−H…πhydrogen bond has garnered significant research interest in recent decades.In this work,we utilized the infrared(IR)-vacuum-ultraviolet(VUV)nonresonant ionization detected IR spectroscopy(NRID-IR)method to study the molecular structure of neutral and cationic 2-methylallyl alcohol(MAA,CH_(2)=C(CH_(3))−CH_(2)−OH).Density functional theory calculations revealed five stable neutral and three stable cationic MAA conformers,respectively.Two neutral MAA conformers are expected to have an O−H…πintramolecular hydrogen bond interaction,based on the structural characterization that the OH group is directed toward the C=C double bond.The IR spectra of both neutral(2700−3700 cm^(−1))and cationic MAA(2500−7200 cm^(−1))were measured,and the anharmonic IR spectra were calculated at the B3LYP-D3(BJ)/def2-TZVPP level.The OH stretching vibration frequency of neutral MAA was observed at 3656 cm−1,slightly lower than those of methanol and ethanol.In contrast,the OH stretching vibration of cationic MAA was red-shifted by about 140 cm^(−1)compared to neutral MAA.The interaction region indicator and natural bond orbital analysis suggest that the O−H…πinteraction in neutral MAA is weak,and may not play a major role in stabilizing the neutral MAA.

纳米颗粒的干燥及其研究进展

由于纳米粒子的表面效应,用湿法制备出的纳米粉体的前驱——胶体的干燥已不能采用传统的干燥方法。本文根据胶体干燥的一般理论,综述了用于纳米颗粒干燥的各种干燥技术、给出了具体实例并分析了不同因素产生的效应。

丙烯酸-甲基丙烯酸共聚物的合成和吸湿性能

采用甲基丙烯酸(MAA)、丙烯酸(AA)为聚合单体,以亚硫酸氢钠-过硫酸铵为引发剂,采用水溶液聚合法制备了聚丙烯酸-甲基丙烯酸P(AA-MAA)。系统地研究了单体浓度、单体配比、反应温度等各项聚合条件对聚合物吸湿性能的影响。在T=20℃、RH=90%条件下,与传统的硅胶、分子筛等吸湿材料的吸湿性能进行了对比。结果表明,硅胶和分子筛在10h内已经逼近吸湿平衡点,而P(AA-MAA)的吸湿率明显>80%且仍未达到其最大吸湿容量。在吸湿性能测试的各个阶段,P(AA-MAA)的吸湿率是它们的5倍以上,明显优于传统的硅胶和分子筛。红外光谱分析证实了P(AA-MAA)共聚物的生成。

海底悬跨管线的地震响应和振动控制

渤海湾地区属于地震高发地区，在此处铺设海底管线必须考虑地震作用的影响。本文基于Ｍｏｒｉｓｏｎ方程建立了悬跨海底管线在地震作用下的动力方程。该方程考虑了海水对管道反应的影响，并对影响悬跨海底管线地震反应的因素进行了分析。在此基础上建议了控制管道反应的方法。

基于数据仓库的决策支持系统体系结构

在分析传统DSS的不足之后,提出了基于数据仓库决策支持系统的体系结构,主要包括模型库、方法库、知识库和数据仓库及其相应的管理系统,联机分析处理、数据挖掘单元和问题综合处理单元等几部分组成 研究了系统中各部分的功能。

食品安全追溯体系实施模式中的企业决策分析

针对企业自有基地生产模式和"农户+合作社+企业"模式的我国两类不同食品安全追溯体系的主要实施模式,通过建立优化模型,分析了两种模式实施追溯体系主体企业的相关决策行为。比较分析结果表明:若合作社农户是风险中性的,两种模式中供给安全农产品的最优努力水平、企业实施追溯体系的最优成功率是相同的,供给不安全食品导致企业损失对最优决策的影响也相同。

一种能量桩热泵系统原理演示的科普教具设计与实践

为直观地展示能量桩热泵系统各个组件间的连接,及系统在供暖制冷不同工况下的运行原理。将热泵系统各个组件简化为常见模型,用灯带及其运动方向展示水流的循环流动,共同拼装为能量桩热泵系统的沙盘模型;同时,对于系统动态的原理演示,采用电子元件结合电路连接的形式进行等效展示。二者结合得到一种能量桩热泵系统原理演示的科普教具。该教具可作为《地基处理技术》《基础工程》等本科课程教学内容的重要拓展,寓教于乐,更好实现技术科普和课程思政。

Assessment of Contemporary Theoretical Methods for Bond Dissociation Enthalpies

The density functional theory （DFT） is the most popular method for evaluating bond dis- sociation enthalpies （BDEs） of most molecules. Thus, we are committed to looking for alternative methods that can balance the computational cost and higher precision to the best for large systems. The performance of DFT, double-hybrid DFT, and high-level com- posite methods are examined. The tested sets contain monocyclic and polycyclic aromatic molecules, branched hydrocarbons, small inorganic molecules, etc. The results show that the mPW2PLYP and G4MP2 methods achieve reasonable agreement with the benchmark val- ues for most tested molecules, and the mean absolute deviations are 2.43 and 1.96 kcal/mol after excluding the BDEs of branched hydrocarbons. We recommend the G4MP2 is the most appropriate method for small systems （atoms number≤20）; the double-hybrid DFT methods are advised for large aromatic molecules in medium size （20≤atoms number≤50）, and the double-hybrid DFT methods with empirical dispersion correction are recommended for long-chain and branched hydrocarbons in the same size scope; the DFT methods are ad- vised to apply for large systems （atoms number〉50）, and the M06-2X and B3P86 methods are also favorable. Moreover, the differences of optimized geometry of different methods are discussed and the effects of basis sets for various methods are investigated.

用摄动法按N～S方程计算分离流及其试验验证

本文根据摄动理论中的Plindstedt——Poincare方法,提出了一种在规则边界面上具有弧立突体的湍流场计算新方法,即在突体附近的规则边界流动区域进行局部坐标摄动变形,然后利用不可压粘性流体流动的有限元法求解N～S方程.该方法成功地模拟了二维等腰三角形弧立突体后不恒定分离流的回流,通过与相平行的试验结果比较表明,两者吻合良好.

Effect of Nb additions on microstructure and properties of γ-TiAl based alloys fabricated by selective laser melting

The γ-TiAl based Ti.Al.Mn.Nb alloys with different Nb additions were fabricated by selective laser melting (SLM) on the TC4 substrate. The effects of Nb content on microstructure and properties of the alloys were investigated. The results reveal that the alloys consist of γ-TiAl phase with tetragonal lattice structure and α2-Ti3Al phase with hcp lattice structure, and show a sequential structure change from near full dendrite to near lamellar structure with the increase of Nb addition. Owing to the higher Nb content in γ-TiAl phase and the formation of near lamellar structure, the alloy with 7.0 at.% Nb addition has the best combination of properties among the studied alloys, namely, not only a high hardness of HV 2000, a high strength of 1390 MPa and a plastic deformation of about 24.5%, but also good tribological properties and high-temperature oxidation resistance.