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  • 文章类型: Journal Article
    半导体光催化在可再生能源发电和环境修复方面具有广阔的前景,但通常在光吸收方面存在严重的缺点,电荷产生和传输,和结构稳定性限制了性能。核-壳半导体-石墨烯(CSSG)纳米结构可以解决这些问题,这是由于其具有优异的物理和化学性质的独特结构。这篇综述探讨了CSSG纳米结构在光催化性能方面的最新进展。它从按维度对CSSG纳米架构进行分类开始。然后,介绍了内外驱动力作用下的施工方法,并进行了比较。之后,讨论了这些纳米结构的物理化学性质和光催化应用,专注于它们在光催化中的作用。最后对CSSG纳米结构向具有广泛应用的高效光催化剂的未来发展进行了总结和展望。通过利用CSSG架构的协同能力,我们的目标是解决紧迫的环境和能源挑战,并推动这些领域的科学进步。
    Semiconductor photocatalysis holds great promise for renewable energy generation and environment remediation, but generally suffers from the serious drawbacks on light absorption, charge generation and transport, and structural stability that limit the performance. The core-shell semiconductor-graphene (CSSG) nanoarchitectures may address these issues due to their unique structures with exceptional physical and chemical properties. This review explores recent advances of the CSSG nanoarchitectures in the photocatalytic performance. It starts with the classification of the CSSG nanoarchitectures by the dimensionality. Then, the construction methods under internal and external driving forces were introduced and compared with each other. Afterward, the physicochemical properties and photocatalytic applications of these nanoarchitectures were discussed, with a focus on their role in photocatalysis. It ends with a summary and some perspectives on future development of the CSSG nanoarchitectures toward highly efficient photocatalysts with extensive application. By harnessing the synergistic capabilities of the CSSG architectures, we aim to address pressing environmental and energy challenges and drive scientific progress in these fields.
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  • 文章类型: Journal Article
    醋酸羟丙基甲基纤维素琥珀酸酯(HPMCAS)是在配制无定形固体分散体(ASD)中选择的聚合物之一,并且通过延迟药物结晶帮助维持高水平的药物过饱和。在这里,HPMCAS化学对快速结晶亲脂性药物的溶液结晶动力学的影响,泊沙康唑(PCZ),通过液-液相分离(LLPS)产生的含水本体相和富含药物的相,被研究过。HPMCAS的三个等级:L,M,H,乙酰基和琥珀酰基取代度(A/S比)不同,进行了比较。聚合物对成核诱导时间的影响,和LLPS浓度的PCZ,以及尺寸,测定纳米尺寸的富含药物的相的ζ-电位和组成。观察到成核诱导时间随着聚合物A/S比的增加而增加。PCZ的荧光发射光谱中的蓝移表明PCZ和HPMCAS之间的相互作用随着A/S比的增加而增加。随着A/S比的增加,也观察到更多的聚合物分配到富含药物的相中,导致更小的液滴。当pH从5.5增加到7.5时,HPMCAS的更大程度的离子化降低了聚合物的疏水性,导致更短的成核诱导时间。ASD释放研究中PCZ的相行为与这些观察结果一致,其中在L级下观察到过饱和的最短持续时间。虽然H级提供了最好的结晶抑制,仅在较高pH下观察到完全释放。因此,HPMCAS等级会影响ASD释放后PCZ结晶的动力学,以及在生理相关pH条件下的释放程度。这项研究提供了对HPMCAS化学和电离作为影响其作为结晶抑制剂的能力的因素的作用的见解。
    Hydroxypropyl methyl cellulose acetate succinate (HPMCAS) is one of the polymers of choice in formulating amorphous solid dispersions (ASDs) and helps to sustain high levels of drug supersaturation by delaying drug crystallization. Herein, the impact of HPMCAS chemistry on the solution crystallization kinetics of a fast-crystallizing lipophilic drug, posaconazole (PCZ), from the aqueous bulk phase and the drug-rich phase generated by liquid-liquid phase separation (LLPS), was studied. Three grades of HPMCAS: L, M, and H, which differ in the degree of acetyl and succinoyl substitution (A/S ratio), were compared. The influence of the polymers on the nucleation induction time, and LLPS concentration of PCZ, as well as the size, ζ-potential and composition of the nano-sized drug-rich phase was determined. An increase in the nucleation induction time was observed with an increase in the polymer A/S ratio. A blue shift in the fluorescence emission spectrum of PCZ suggested a greater extent of interaction between PCZ and HPMCAS with an increase in the A/S ratio. More polymer partitioning into the drug-rich phase was also observed with an increase in the A/S ratio, resulting in smaller droplets. A greater extent of ionization of HPMCAS upon increasing the pH from 5.5 to 7.5 decreased the hydrophobicity of the polymer resulting in shorter nucleation induction times. The phase behavior of PCZ in ASD release studies was consistent with these observations, where the shortest duration of supersaturation was observed with the L grade. Although the H grade provided the best inhibition of crystallization, complete release was only observed at higher pH. HPMCAS grade thus influences the kinetics of PCZ crystallization following release from an ASD, as well as the extent of release at physiologically relevant pH conditions. This study provides insights into the role of HPMCAS chemistry and ionization as factors influencing its ability to act as a crystallization inhibitor.
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  • 文章类型: Journal Article
    这项同时进行的定性研究的主要目的是确定野生动物的信仰,禁忌,usages,健康观念,从2020年11月至2021年1月,泰国德省和MaeHongSon省四个社区的十个族裔群体的做法。我们还收集了研究受访者与可能导致人畜共患疾病传播和感染的潜在危险行为相关的全面信息。此外,我们打算利用这项研究的结果来制定沟通策略和健康素养改善干预措施,以减轻危险行为,重点关注居住在森林和野生动物附近的种族群体和特定个人,以防止未来的流行病。六十五名受访者是根据他们广泛的知识有目的地挑选的,积极参与当地文化背景,信仰,接触野生动物或食用野生动物。20人(30.8%)参加了深度访谈(IDI),45人(69.2%)参加了8次重点小组讨论(FGD)。结果表明,根据不同种族和研究地点之间的信仰和禁忌,野生动物接触的特征相似和不同。受文化背景和传统的影响。虽然有些民族对野生动物的消费没有明确的限制,其他人坚持特定的信仰和禁忌,禁止食用或杀死特定的野生动物。这些信念经常与保护倡议相对应,从而促进受威胁物种的保护。该研究还显示缺乏适当的健康知识,感知,以及有关野生动物接触和消费的做法。因此,建议公共卫生官员和地方政府制定和执行沟通和教育计划。这些运动应旨在提高健康素养并促进安全处理,准备,和烹饪方法,以有效降低人畜共患疾病传播和感染的风险。此外,有必要设计和实施野生动物保护教育和推广活动。这些计划应在考虑文化背景的同时促进环境管理,信仰,和各种民族的做法。这些活动应涉及不同的利益相关者,包括当地领导人,宗教影响者,社区成员,学校教师,学生,卫生专业人员,村卫生志愿者,和民间社会组织。
    This concurrent qualitative study was carried out with the main objective to determine wildlife beliefs, taboos, usages, health perceptions, and practices among ten ethnic groups in four communities in Tak and Mae Hong Son provinces of Thailand from November 2020 to January 2021. We also gathered comprehensive information on study respondents\' knowledge related to potential risk behaviors that could lead to zoonotic disease transmission and infection. Furthermore, we intended to use the study\'s findings to develop communication strategies and health literacy improvement interventions for mitigating risky behaviors, with a focus on ethnic groups and particular individuals who live in close proximity to forests and wildlife, to prevent future pandemics. Sixty-five respondents were purposively selected based on their extensive knowledge, active participation in local cultural contexts, beliefs, and exposure to wildlife contact or consuming game animals. Twenty (30.8%) participated in in-depth interviews (IDIs), while 45 (69.2%) participated in eight focused group discussions (FGDs). The results revealed that the characteristics of wildlife contact are similar and distinct based on their beliefs and taboos among various ethnic groups and study locations, which are influenced by cultural backgrounds and traditions. Although some ethnic groups do not have explicit restrictions on the consumption of wildlife, others adhere to specific beliefs and taboos that forbid the consumption or killing of specific wild animals. These beliefs frequently correspond with conservation initiatives, thereby facilitating the preservation of threatened species. The study also revealed a lack of appropriate health knowledge, perceptions, and practices regarding wildlife contact and consumption. As a result, it is recommended that public health officials and local governments develop and execute communication and education initiatives. These campaigns should aim to increase health literacy and promote safe handling, preparation, and cooking practices to reduce the risk of zoonotic disease transmission and infection effectively. Moreover, it is necessary to design and implement wildlife conservation education and outreach activities. The programs should promote environmental stewardship while considering the cultural contexts, beliefs, and practices of various ethnic groups. The activities should involve diverse stakeholders, including local leaders, religious influencers, community members, schoolteachers, students, health professionals, village health volunteers, and civil society organizations.
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  • 文章类型: Journal Article
    磨损是一种普遍存在的现象,它通过逐渐去除材料来限制许多具有滑动界面的工程部件的寿命。聚合物的磨损在许多应用中至关重要,从轴承到整形外科植入物到纳米光刻工艺。聚合物的磨损率受到界面处的应力和温度的强烈影响。通常根据经验描述温度和应力的影响,因为磨损过程涉及在一定长度范围内粗糙表面上多个凹凸之间的复杂相互作用。单凹凸级别的纳米级摩擦学实验为磨损的潜在机制提供了新的见解。硬共价键合材料的实验,包括硅和钻石,已经证明磨损是原子磨耗磨损过程,可以使用应力辅助过渡态理论进行建模。这里,我们检查普通聚合物的磨损,聚甲基丙烯酸甲酯(PMMA),在纳米尺度上作为应力和温度的函数,表明聚合物的磨损是由原子磨损和粘弹性松弛的组合控制的。虽然磨损实验是通过原子力显微镜在纳米级进行的,结果表明,考虑在接触界面的局部应力分布是理解磨损行为的关键,在早期对硬质材料的研究中没有考虑到这种影响。使用一个解释压力分布的模型,我们证明了预测磨损体积在8%以内的能力。
    Wear is a ubiquitous phenomenon that limits the life of many engineered components with sliding interfaces through the gradual removal of material. The wear of polymers is crucial in many applications, ranging from bearings to orthopedic implants to nanolithography processes. The wear rate of polymers is strongly affected by the stress and temperature at the interface. The effects of temperature and stress are often described empirically since the wear process involves complex interactions between multiple asperities on rough surfaces over a range of length scales. Nanoscale tribology experiments at the single-asperity level have provided new insights into the underlying mechanisms of wear. Experiments on hard covalently bonded materials, including silicon and diamond, have demonstrated that wear is an atomic attrition wear process that can be modeled using stress-assisted transition state theory. Here, we examine the wear of a common polymer, polymethylmethacrylate (PMMA), at the nanoscale as a function of stress and temperature and show that the polymer wear is controlled by a combination of atomic attrition and viscoelastic relaxation. While the wear experiments are conducted at the nanoscale via atomic force microscopy, the results show that accounting for the local stress distribution at the contact interface is critical to understanding the wear behavior, an effect that was not considered in earlier studies on hard materials. Using a model that accounts for the stress distribution, we demonstrate the ability to predict the wear volume within 8%.
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  • 文章类型: Journal Article
    具有延长循环寿命的柔性电极的开发和应用一直是能源研究领域的焦点。在这项研究中,将带负电荷的带正电荷的聚乙烯亚胺(PEI)和导电聚合物聚(3,4-亚乙基二氧噻吩):聚(苯乙烯磺酸盐)(PEDOT:PSS)利用压力梯度辅助逐层(LbL)自组装技术交替沉积到纤维素纳米纤维(CNF)多孔材料上。柔性基板,以刚性CNF增强的三维多孔结构为特征,通过减少PEDOT:PSS的体积变化,不仅促进了高电荷存储,而且提高了电极的循环寿命。此外,电解质对PEI的优异润湿性可以促进电极内的有效电荷传输。具有10个PEI/PEDOT:PSS双层的电极在5mVs-1的扫描速率下表现出63.71Fg-1的电容,并且在3000次充电-放电循环后具有128%的显着电容保持率。对LbL多层结构的纳米级层的研究表明,出色的循环性能主要归因于刚性多孔基材分层结构对PEDOT:PSS变形的空间约束。这项工作有望为开发具有高电荷存储容量和超长循环寿命的电极做出重大贡献。
    The development and application of flexible electrodes with extended cycle life have long been a focal point in the field of energy research. In this study, positively charged polyethylene imine (PEI) and conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with negative charge were alternately deposited onto a cellulose nanofiber (CNF) porous material utilizing pressure gradient-assisted layer-by-layer (LbL) self-assembly technology. The flexible substrate, characterized by a three-dimensional porous structure reinforced with stiff CNF, not only facilitated high charge storage but also enhanced the electrode\'s cycling life by reducing the volume changes of PEDOT:PSS. Furthermore, the exceptional wettability of PEI by the electrolyte could promote efficient charge transport within the electrode. The electrode with 10 PEI/PEDOT:PSS bilayer exhibits a capacitance of 63.71 F g-1 at the scan rate of 5 mV s-1 and a remarkable capacitance retention of 128 % after 3000 charge-discharge cycles. The investigation into the nanoscale layers of the LbL multilayer structure indicated that the exceptional cyclic performance was primarily attributed to the spatial constraints imposed by the rigid porous substrate layered structure on the deformation of PEDOT:PSS. This work is expected to make a significant contribution to the development of electrodes with high charge storage capacity and ultra-long cycling life.
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  • 文章类型: Journal Article
    广泛理解STIM1的构象变化,该构象变化将ER钙存储消耗的感知从STIMER腔结构域传递到STIM细胞质区域,并最终传递到质膜中的ORAI通道。然而,驱动构象变化的STIM腔结构域二聚化的结构基础已被证明是难以捉摸的。最近发表的一项研究通过分子动力学模拟来解决这个问题。该报告指出了可能是腔域二聚化界面的一部分的STIM残基,并提供了有关STIM腔结构域的扭转运动如何触发细胞质SOAR/CAD结构域从其静止系链释放到STIMCC1片段的意外见解。
    The conformational change in STIM1 that communicates sensing of ER calcium-store depletion from the STIM ER-luminal domain to the STIM cytoplasmic region and ultimately to ORAI channels in the plasma membrane is broadly understood. However, the structural basis for the STIM luminal-domain dimerization that drives the conformational change has proven elusive. A recently published study has approached this question via molecular dynamics simulations. The report pinpoints STIM residues that may be part of a luminal-domain dimerization interface, and provides unexpected insight into how torsional movements of the STIM luminal domains might trigger release of the cytoplasmic SOAR/CAD domain from its resting tethers to the STIM CC1 segments.
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  • 文章类型: Journal Article
    稀土(RE)元素由于其独特的4f电子构型和强大的轨道耦合而对自旋磁调制具有吸引力。将RE与常规的3d过渡金属(TM)合金化有望用于制造先进的自旋催化剂,但在制备方面仍然存在很多困难,这导致了RE和3dTM之间的自旋磁效应对催化作用的奥秘。在这里,我们定义了一个固相合成协议,用于创建RE-3dTM-贵金属集成颗粒内异质结构纳米合金(IHA),在整个Rh框架内具有不同的Gd和Co界面,表示为RhCo-RhGdIHA。它们表现出界面触发的反铁磁相互作用,可以诱导电子重新分布和调节自旋极化。理论计算进一步表明,自旋极化减弱的异质界面周围的活性位点优化了H2O的吸附和解离,从而促进碱性析氢催化。RhCo-RhGdIHA在10mAcm-2时显示出11.3mV的小过电位,以及显着的长期稳定性,远远优于以前报道的Rh基催化剂。
    Rare earth (RE) elements are attractive for spin-magnetic modulation due to their unique 4f electron configuration and strong orbital couplings. Alloying RE with conventional 3d transition-metal (TM) is promising for the fabrication of advanced spin catalysts yet remains much difficulties in preparation, which leads to the mysteries of spin-magnetic effect between RE and 3d TM on catalysis. Here we define a solid-phase synthetic protocol for creating RE-3d TM-noble metal integrated intraparticle heterostructured nanoalloys (IHAs) with distinct Gd and Co interface within the entire Rh framework, denoted as RhCo-RhGd IHAs. They exhibit interface-triggered antiferromagnetic interaction, which can induce electron redistribution and regulate spin polarization. Theoretical calculations further reveal that active sites around the heterointerface with weakened spin polarization optimize the adsorption and dissociation of H2O, thus promoting alkaline hydrogen evolution catalysis. The RhCo-RhGd IHAs show a small overpotential of 11.3 mV at 10 mA cm-2, as well as remarkable long-term stability, far superior to previously reported Rh-based catalysts.
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  • 文章类型: Journal Article
    聚乙二醇(PEG),尽管是研究最多的聚合物电解质,遭受严重的缺点,这需要对锂电池性能不佳的背后进行基础研究。这里,我们报告了末端基团对带有羟基(TPEG-OH)或碳酸酯-酮(TPEG-Carb-ket)末端基团的三臂PEG星的影响。后者通过由TPEG-OH的-OH端基引发的开环反应合成,并产生碳酸酯-酮官能团。的确,通过将链的反应性集中在末端基团上,发现修饰的链端充当牺牲基团,保护其余的TPEG分子,这显著减少了界面降解,并实现了高达4.47V的更宽的电化学稳定性窗口,高库仑效率,和容量保留。此外,在超过1200小时的剥离和电镀之后,其显示出与锂金属的稳定界面。当在基于LiFePO4阴极和Li阳极的参考电池中研究这些电解质时,对于TPEG-Carb-ket和TPEG-OH电解质,从118.7到113.8和108.9到5.03mAhg-1观察到放电容量的变化,分别,从第1周期到第100周期。密度泛函理论计算和从头算分子动力学模拟进一步支持了实验结果。
    Poly(ethylene glycol) (PEG), despite being the most studied polymer electrolyte, suffers from serious drawbacks, which require fundamental studies behind its underperformance in lithium batteries. Here, we report the effect of the terminal group on triarm PEG stars bearing either hydroxyl (TPEG-OH) or carbonate-ketone (TPEG-Carb-ket) terminal groups. The latter is synthesized by a ring-opening reaction triggered by the -OH end group of TPEG-OH and results in a carbonate-ketone functionality. Indeed, the modified chain end is found to act as a sacrificial group by focusing the reactivity of the chain on the terminal group, protecting the rest of the TPEG molecule, which significantly reduces interfacial degradation and achieves a broader electrochemical stability window of up to 4.47 V, high Coulombic efficiency, and capacity retention. It furthermore demonstrates a stable interface with lithium metal after more than 1200 h of stripping and plating. When those electrolytes are investigated in reference cells based on LiFePO4 cathodes and Li anodes, the change in discharge capacity is observed from 118.7 to 113.8 and 108.9 to 5.03 mAh g-1 for TPEG-Carb-ket and TPEG-OH electrolytes, respectively, from the 1st to 100th cycle. The experimental results are further supported by density functional theory calculations and ab initio molecular dynamics simulations.
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  • 文章类型: Journal Article
    这项研究的目的是研究市售的高强度聚邻苯二甲酰胺基复合材料的摩擦学特性(30-50wt。%)的碳纤维和玻璃纤维在干摩擦和油润滑条件下在各种负载和滑动速度下与金属和陶瓷配合面的点和线性接触。两种类型的纤维的长度与其含量同时变化,而样品是通过注塑成型由颗粒制成的。当负载30重量的PPA时。%SCF在长径比(AR)为200时,极限拉伸强度和弹性模量增加到142.7±12.5MPa和12.9±0.6GPa,分别。增强纤维PPA/40CCF和AR~1000含量较高的复合材料的极限拉伸强度和弹性模量分别为240±3MPa和33.7±1.9GPa。分别。在所应用的测试条件下,用40重量%增强的复合材料。在长径比为〜1000时,最大100μm长的碳纤维具有最佳的机械性能和摩擦学特性。改善复合材料摩擦学特性应考虑的原因之一是疲劳磨损机理,这是由高填充度促进的,强的界面附着力,和纤维的大长径比。在油润滑条件下,摩擦系数和磨损率都降低了,所以这种摩擦单元可以尽可能地实施。报告的数据可用作将纤维状聚邻苯二甲酰胺基复合材料用作摩擦单元组件的实用建议。
    The aim of this study was to investigate the tribological characteristics of commercially available high-strength polyphthalamide-based composites with great contents (30-50 wt.%) of both carbon and glass fibers in point and linear contacts against metal and ceramic counterfaces under dry friction and oil-lubricated conditions at various loads and sliding speeds. The lengths of both types of fibers were varied simultaneously with their contents while samples were fabricated from granules by injection molding. When loading PPA with 30 wt.% SCFs at an aspect ratio (AR) of 200, the ultimate tensile strength and the elastic modulus increased up to 142.7 ± 12.5 MPa and 12.9 ± 0.6 GPa, respectively. In the composites with the higher contents of reinforcing fibers PPA/40CCF and AR~1000, the ultimate tensile strength and the elastic modulus were 240 ± 3 MPa and 33.7 ± 1.9 GPa, respectively. Under the applied test conditions, a composite reinforced with 40 wt.% carbon fibers up to 100 μm long at an aspect ratio of ~1000 possessed the best both mechanical properties and tribological characteristics. One of the reasons that should be considered for improving the tribological characteristics of the composite is the fatigue wear mechanism, which is facilitated by the high filling degree, the strong interfacial adhesion, and the great aspect ratio for fibers. Under the oil-lubricated conditions, both friction coefficients and wear rates decreased, so such friction units could be implemented whenever possible. The reported data can be used as practical recommendations for applying fibrous polyphthalamide-based composites as friction unit components.
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  • 文章类型: Journal Article
    纤维增强复合材料通常暴露在与水分和溶液相关的环境中,导致吸收,这导致了本体树脂的变化,纤维-基质界面,甚至纤维本身。有关吸收行为和扩散机制和特性的知识对于更好地了解这些材料对通过服务而面临的环境暴露的响应,以通过选择成分来开发更好的材料以及对长期耐久性的预测至关重要。本文回顾了吸收机制和后续反应的各个方面,以及描述吸附过程的模型,目的是全面了解与水分吸收有关的现象和特征,例如吸收速率,扩散和弛豫/劣化常数,政权过渡,和整体反应。
    Fiber-reinforced composites are commonly exposed to environments associated with moisture and solution, resulting in uptake, which causes changes in the bulk resin, the fiber-matrix interface, and even the fiber itself. Knowledge about uptake behavior and diffusion mechanisms and characteristics are critical to better understanding the response of these materials to environmental exposure faced through service to developing better materials through selection of constituents and to the prediction of long-term durability. This paper reviews aspects of uptake mechanisms and subsequent response, as well as models that describe the sorption process, with the aim of providing a comprehensive understanding of moisture-uptake-related phenomena and characteristics such as uptake rate, diffusion and relaxation/deterioration constants, transitions in regimes, and overall response.
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