Smart heat isolator with hollow multishelled structures

Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks.Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5℃ can be achieved for the TSPU/3S–TiO_(2)HoMSs with a thickness of 1 mm under the temperature field of 50℃.The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.

咪唑类离子液体与酪氨酸相互作用及机理的密度泛函理论研究

离子液体的物理化学性质稳定且结构可调,被认为是潜在的新一代绿色高效生物分子溶剂。本文通过密度泛函理论研究了系列咪唑基离子液体与两性离子型氨基酸(酪氨酸)的相互作用及机理。利用对称微扰理论(SAPT)、分子中的原子理论(AIM)及约化密度梯度函数(RDG),分析了氢键作用、静电力、诱导力和色散力对离子液体-氨基酸体系相互作用的贡献。计算结果表明静电作用对于阴、阳离子与酪氨酸的相互作用占主导地位。对于系列阳离子而言,具有不同的甲基取代位点和烷基侧链长度对不同的相互作用模式会产生显著影响。其中,当甲基位于咪唑环的C2位点时,诱导力与色散力占比差别较小;当甲基取代位于咪唑环的N3位点时,诱导力与色散力占比差别较大。产生这一差异的原因在于当甲基位于C2位时,氢键、咪唑环与苯环之间的π^(+)–π作用为主要作用模式,而甲基取代位为N3位时,氢键和烷基链与苯环之间的C_(Alkyl)―H…π作用则成为主导。进一步获得离子对-酪氨酸的相互作用能变化趋势与阳离子-酪氨酸的变化趋势一致,阴阳离子的共同作用使其与酪氨酸结合更稳定。该研究结果阐明了离子液体中阳离子氢键位点及侧链长度差异对于离子液体-酪氨酸体系的相互作用模式的影响机制,为高效分离氨基酸的功能性离子液体的设计和筛选提供了新思路。

High CO_(2) absorption capacity of metal-based ionic liquids: A molecular dynamics study

The absorption of CO_(2)is of importance in carbon capture,utilization,and storage technology for greenhouse gas control.In the present work,we clarified the mechanism of how metal-based ionic liquids (MBILs),Bmim[XCl_(n)]_(m)(X is the metal atom),enhance the CO_(2)absorption capacity of ILs via performing molecular dynamics simulations.The sparse hydrogen bond interaction network constructed by CO_(2)and MBILs was identified through the radial distribution function and interaction energy of CO_(2)-ion pairs,which increase the absorption capacity of CO_(2)in MBILs.Then,the dynamical properties including residence time and self-diffusion coefficient confirmed that MBILs could also promote the diffusion process of CO_(2)in ILs.That's to say,the MBILs can enhance the CO_(2)absorption capacity and the diffusive ability simultaneously.Based on the analysis of structural,energetic and dynamical properties,the CO_(2)absorption capacity of MBILs increases in the order Cl^-→[ZnCl_(4)]^(2-)→[CuCl_(4)]^(2-)→[CrCl_(4)]^-→[FeCl_(4)]^-,revealing the fact that the short metal–Cl bond length and small anion volume could facilitate the performance of CO_(2)absorbing process.These findings show that the metal–Cl bond length and effective volume of the anion can be the effective factors to regulate the CO_(2)absorption process,which can also shed light on the rational molecular design of MBILs for CO_(2)capture and other key chemical engineering processes,such as IL-based gas sensors,nano-electrical devices and so on.

Surface composition dominates the electrocatalytic reduction of CO2 on ultrafine CuPd nanoalloys

Preciously tuning the surface composition of noble metal nanoparticles with the particle size of only 2 nm or less by alloying with other metals represents a powerful strategy to boost their electrocatalytic selectivity.However,the synthesis of ultrafine nanoalloys and tuning their surface composition remain challenging.In this report,ultrafine CuPd nanoalloys with the particle size of ca.2 nm are synthesized based on the galvanic replacement reaction between presynthesized Cu nanoparticles and Pd2+precursors,and the tuning of their surface compositions is also achieved by changing the atom ratios of Cu/Pd.For the electrocatalytic reduction of CO2,Cu5Pd5 nanoalloys show the CO Faradaic efficiency(FE)of 88%at−0.87 V,and the corresponding mass activity reaches 56 A/g that is much higher than those of Cu8Pd2 nanoalloys,Cu3Pd7 nanoalloys and most of previously reported catalysts.Density functional theory uncovers that with the increase of Pd on the surface of the ultrafine CuPd nanoalloys,the adsorbed energy of both of intermediate COOH*and CO*to the Pd sites is strengthened.The Cu5Pd5 nanoalloys with the optimal surface composition better balance the adsorption of COOH*and desorption of CO*,achieving the highest selectivity and activity.The difficult liberation of absorbed CO*on the surface of Cu3Pd7 nanoalloys provides carbon source to favor the production of ethylene,endowing the Cu3Pd7 nanoalloys with the highest selectivity for ethylene among these ultrafine CuPd nanoalloys.

Mechanical responses of the bio-nano interface: A molecular dynamics study of graphene-coated lipid membrane

Bio-nano interfaces between biological materials and functional nanodevices are of vital importance in relevant energy and information exchange processes, which thus demand an in-depth understanding. One of the critical issues from the application viewpoint is the stability of the bio-nano hybrid under mechanical perturbations. In this work we explore mechanical responses of the interface between lipid bilayer and graphene under hydrostatic coating provides remarkable resistance to the pressure or indentation loads, We find that graphene loads, and the intercalated water layer offers additional protection. These findings are discussed based on molecular dynamics simulation results that elucidate the molecular level mechanisms, which provide a basis for the rational design of bionanotechnology- enabled aoolications such as biomedical devices and nanotheraoeutics.

A new era of precise liquid regulation:Quasi-liquid

Common in nature and artificial systems,quasi-liquid represents a special phase under specific conditions,where precise regulations can be conducted to accommodate various applications,such as material,biology,life and manufacture.

纳微尺度热力学与前沿应用

在实际化工过程中,纳微尺度界面体系普遍存在,且与反应和传递等过程高度耦合.这种耦合增加了直接应用宏观热力学模型和规律的难度,进而在工程预测、放大及调控方面带来挑战,制约了绿色化工技术创新和规模应用的发展.本文针对纳微尺度热力学的起源、内涵及其在前沿领域的应用进行了深入探讨.首先,以绿色介质离子液体为例,展示了纳微尺度下的独特界面结构和功能,讨论了离子液体结构–功能间的纳微尺度热力学关联机制;然后,概述了适用于纳微尺度热力学领域的研究方法,提出了集合高精度原位动态实验、精准高效计算模拟和高通量自动化人工智能相结合的研究范式;随后,总结了纳微尺度热力学理论在反应、分离和电化学领域的前沿应用,并对其挑战和未来机遇进行了深入讨论和展望.总之,纳微尺度热力学的新理论和新方法,不仅可以为化工学科的科学研究开辟新的视野和路径,还将推动化工过程实现从“分子设计→结构功能调控→工程放大规律”的跨越,催生出适应于新体系、新应用和新需求的化工热力学新学科.

Ionic liquid-trimetallic electrocatalytic system for C–O bond cleavage in lignin model compounds and lignin under ambient conditions

Electrocatalytic depolymerization of lignin into value-added chemicals offers a promising technique to make biorefining sustainable.Herein,we report a robust trimetallic PdNiBi electrocatalyst for reductive C–O bond cleavage of different lignin model dimers and oxidized lignin under mild conditions.The reduction reaction proceeds with complete substrate conversion and excellent yields toward monomers of phenols(80%–99%)and acetophenones(75%–96%)in the presence of an ionic liquid electrolyte with operational stability.Systematic experimental investigations together with density functional theory(DFT)calculations reveal that the outstanding performance of the catalyst results from the synergistic effect of the metal elements,which facilitates the easier formation of a key Cαradical intermediate and the facile desorption of the as-formed products at the electrode.The results open up new opportunities for lignin valorization through the green electrocatalytic approach.

Smart ionic liquid/water mixture system with dual stimuli-response to temperature and CO_(2)

Stimuli-responsive materials have important applications in chemistry and chemical engineering.Here,we synthesized five different polyetheramine-fatty acids(PEFA)ionic liquids(ILs),possessing the dual stimuli-responsive ability to temperature and CO_(2).These PEFA ILs have reversible lower critical solution temperature(LCST)phase behavior over a wide temperature range of 37-91℃,and reversible heterogeneous-homogeneous phase transition towards the addition and removal of CO_(2).Furthermore,the droplet size of the IL-water mixture system increased from 6.5 to 21.0 nm as the temperature increased from 25 to 56℃,and then recovered to 6.5 nm when the temperature decreased to 25℃.The addition and removal of CO_(2)also reversibly modulated the droplet size of the system.Results from nuclear magnetic resonance(NMR)and Fourier transform infrared(FTIR)spectra further showed that the temperature-dependent conformation of polyether amine chain in the cation dominates the temperature response,while the reversible formation of bicarbonate and fatty acids(FA)from CO_(2)and anion controls the CO_(2)-based reversible phase transition.Molecular simulations revealed a microscopic response mechanism of the IL-water system to temperature and CO_(2),and a synergistic effect between the dual stimuli of temperature and CO_(2).These findings may provide a basis for the rational design and understanding of ILs-based stimuli-responsive materials and nanoreactors.

Can XunTian Tai Chi intervention improve the level of emotional regulation of crew members in the Controlled Ecological Life Support System?

To explore the appropriate exercise methods and means for astronauts in confined and small isolation conditions,a set of XunTian Tai Chi suitable for the spaceflight workforce was created,with the aim of discovering the practical effects of XunTian Tai Chi and providing a scientific basis for the subsequent development of new astronaut health maintenance techniques with Chinese characteristics.Using the Controlled Ecological Life Support System(CELSS)as a research platform,we observed the changes in a crew member’s emotion regulationrelated indexes during 180 days of working and living in a confined isolation chamber through periodic interventions of the XunTian Tai Chi and conducted statistical analyses.During the 180-day cabin mission,expression suppression,cognitive reappraisal,attention index,and relaxation index were all lower than those before entering the cabin,suggesting that the crew member’s emotion regulation ability decreased during the incabin mission.A single Tai Chi exercise could cause favorable changes in the indicators,positively affecting the crew member's emotional regulation.The attention and relaxation indices of the occupants were improved significantly by both single and periodic Tai Chi exercises.After the Tai Chi exercise cycle,the results of each index showed a certain degree of effect.The 180-day ground-based simulation of Tai Chi in the confinement of a space capsule positively affects the occupant’s emotional regulation.

短链多硫化物在离子液体中聚集行为的分子动力学模拟

离子液体因其优异的物化性质、能抑制多硫化物溶解等特点,近年来被广泛应用于锂硫电池电解液中。在电池充放电产物中,难溶性Li_(2)S和Li_(2)S_(2)易聚集沉积在电极表面,影响电池性能,而目前关于其团聚行为与电解液性质的微观机理研究较少。本工作利用量化计算和分子动力学模拟分析了短链Li_(2)S和Li_(2)S_(2)在离子液体中的微观结构以及形成团簇的情况。通过分析体系的微观结构发现,阳离子中主要与S作用的是侧链甲基,短链多硫化物之间Li-S作用远强于与阴离子的Li-O作用。团簇尺寸分布的结果表明,短链多硫化物在[TFSI]型离子液体中易形成多分子的大团簇,Li_(2)S_(2)体系比Li_(2)S体系中的大团簇比例更高;离子液体阴离子配位能力越强,形成大的Li_(2)S团簇比例越少,但阴离子的构型特点和作用形式也会对团簇的尺寸结构造成影响。

离子液体二维结构制备及其特性研究进展

由于阴阳离子间特殊的静电、氢键作用,具有二维结构的离子液体呈现出独特的结构特征及热力学、动力学特性,在化学化工和材料领域都有着巨大的应用前景,已成为离子液体领域重要的研究方向之一.本综述重点介绍了离子液体二维结构常用的制备方法,包括自组装法、Langmuir-Blodgett法以及物理气相沉积法,并总结了这些制备方法相应的优缺点.随后归纳了离子液体二维结构的相变特征及在力学和电学方面的特性,并综述了其在摩擦润滑领域的应用.最后展望了离子液体二维结构的发展方向及应用前景.

Mesoscale structures and mechanisms in ionic liquids

Ionic liquids(ILs)have attracted intensive attention and have been used widely in many applications because of their diversified properties,which are caused by the special structure of the ILs.Ionic clusters are one of the typical structures that exist widely in the IL system.They are stable under certain conditions and change under other conditions.Ionic clusters are a typical mesoscale phenomenon in mesoscience.In this review,we summarize our recent progress related to ionic clusters,including the ionic-cluster structure,changing mechanisms,and their effect on the physicochemical properties.IL cluster investigation based on mesoscience is very important,will provide new insight into the structures and properties of ILs,and will boost further exploration of IL applications.

Investigations on dehydration processes of trisodium citrate hydrates

The dehydration processes of trisodium citrate （Na3C6H507） hydrates were investigated using thermogravimetry （TG）, differential scanning calorimetry （DSC） and powder X-ray diffraction （PXRD）. It was found that the temperature of dehydration of trisodium citrate dihydrate was at 430.99 K. For trisodium citrate pentahydrate, there is a two-step dehydration process and the endothermal peaks appear at 337.23 K and 433.83 K, respectively. During the first step of dehydration process, the structure oftrisodium citrate pentahydrate changed into the structure oftrisodium citrate dihydrate. In addition, the kinetics of dehydration for trisoidum citrate hydrates was also investigated using TG data. According to the activation energies of dehydration calculated by Ozawa equation, it was found that the dehydration mechanisms of the two hydrates were different.

The Astronaut Center of China 90-d Head-Down Bed Rest:Overview,Countermeasures,and Effects

Countermeasures in weightlessness are a predominant technique for long-term residency in space.Head-down bed rest(HDBR)has long been used to simulate the physiological effects of spaceflight and test the efficacy of countermeasures.In 2019,the Astronaut Center of China(ACC)has held a 90-d HDBR on the effects of exercises’intervention.Thirty-six subjects were recruited and randomized into 5 intervention groups:(a)control,(b)aerobic exercises,(c)resistance exercises,(d)concurrent aerobic and lower load resistance exercises,and(e)concurrent aerobic and high-load resistance exercises.Moreover,exercise interventions were performed in supine or 6°head-down tilt.They were provided with plain medical,psychological,and nutritional supports during the experiment.In addition,cardiovascular and pulmonary functions,muscle strength,bone density,and neuro-immune-endocrine functions were assessed over time.Subjects were monitored by clinical evaluations,psychological assessments,and nutritional status evaluations.All subjects spent 138 d in the bed rest study laboratory and received 2 follow-up tests per 3 months in the home recovery period.It was found that exercises in the 4 groups were effective interventions for aerobic capacity compared with control.The resistance exercises or concurrent aerobic and high-load resistance exercises improved isometric maximal voluntary contraction.However,the protection against bone loss still needs further exploration.Appropriate psychosocial and nutrition support techniques are worth to be reinforced.