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  • 文章类型: Journal Article
    半个多世纪前,模拟变得可行,使用经典机械运动方程,计算机上分子系统的动力学。从那时起,经典物理分子模拟已成为化学研究不可或缺的一部分。它广泛应用于各种化学分支,并为化学知识的发展做出了重大贡献。它提供了对实验结果的理解和解释,对物质的可测量和不可测量性质的半定量预测,并允许在实验无法达到的条件下计算分子系统的性质。然而,分子模拟建立在许多假设之上,近似值,和简化限制了其适用范围和准确性。这些涉及使用的势能函数,分子系统庞大的统计力学构型空间的充分采样,以及用于从统计力学集合中计算化学系统特定特性的方法。在过去的半个世纪中,已经提出了各种方法论思想来提高经典物理分子模拟的效率和准确性。调查,评估,在通用仿真软件中实现或被放弃。后者由于根本缺陷或,虽然身体健全,计算效率低下。简要回顾了其中一些方法论思想,并强调了最有效的方法。讨论了经典物理模拟的局限性,并概述了观点。
    More than a half century ago it became feasible to simulate, using classical-mechanical equations of motion, the dynamics of molecular systems on a computer. Since then classical-physical molecular simulation has become an integral part of chemical research. It is widely applied in a variety of branches of chemistry and has significantly contributed to the development of chemical knowledge. It offers understanding and interpretation of experimental results, semiquantitative predictions for measurable and nonmeasurable properties of substances, and allows the calculation of properties of molecular systems under conditions that are experimentally inaccessible. Yet, molecular simulation is built on a number of assumptions, approximations, and simplifications which limit its range of applicability and its accuracy. These concern the potential-energy function used, adequate sampling of the vast statistical-mechanical configurational space of a molecular system and the methods used to compute particular properties of chemical systems from statistical-mechanical ensembles. During the past half century various methodological ideas to improve the efficiency and accuracy of classical-physical molecular simulation have been proposed, investigated, evaluated, implemented in general simulation software or were abandoned. The latter because of fundamental flaws or, while being physically sound, computational inefficiency. Some of these methodological ideas are briefly reviewed and the most effective methods are highlighted. Limitations of classical-physical simulation are discussed and perspectives are sketched.
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  • 文章类型: Journal Article
    预计由碳纳米管(CNT)和铜(Cu)制成的复合材料同时具有机械性能和电性能,但高含量碳纳米管的低损伤分散和高质量复合材料一直是研究的难点。在本文中,制备了高含量CNTs/Cu复合材料。烧结方法的影响,烧结温度,定向轧制和相对密度上的碳纳米管含量,研究了复合材料的硬度和电导率。通过球磨实现了高含量CNTs在Cu基体中的均匀分散,烧结和轧制,并且该过程没有对CNT造成更大的损害。比较了放电等离子烧结(SPS)和真空热压烧结(HPS)制备的复合材料的性能,并确定了SPS的最佳工艺参数。当CNT含量为2重量%时。%,硬度为134.9HBW,仍然是纯铜的2.3倍,电导率最高,达到78.4%IACS。本研究为高含量CNTs/Cu复合材料的高质量制备和性能评价提供了重要参考依据。
    It is expected that composites made of carbon nanotubes (CNT) and copper (Cu) display both mechanical and electrical properties, but the low damage dispersion and high-quality composite of high-content CNTs have always been research difficulties. In this paper, high-content CNTs/Cu composites were prepared. The effects of the sintering method, sintering temperature, directional rolling and the CNTs\' content on the relative density, hardness and electrical conductivity of the composites were studied. The uniform dispersion of high-content CNTs in Cu matrix was achieved by ball milling, sintering and rolling, and the processes did not cause more damage to the CNTs. The properties of composites prepared by spark plasma sintering (SPS) and vacuum hot pressing sintering (HPS) were compared, and the optimum process parameters of SPS were determined. When the CNTs\' content is 2 wt.%, the hardness is 134.9 HBW, which is still 2.3 times that of pure Cu, and the conductivity is the highest, reaching 78.4%IACS. This study provides an important reference for the high-quality preparation and performance evaluation of high-content CNTs/Cu composites.
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  • 文章类型: Journal Article
    作为一种重要的胶凝材料,胶凝材料在土木工程建设中应用广泛。目前,使用实验和数值图像处理方法对这些材料进行研究,这使得能够观察和分析结构变化和机械性能。这些方法有助于设计具有特定性能标准的胶凝材料,尽管它们的资源密集型性质。材料基因组方法代表了材料研究和开发的新趋势。材料基因数据库的建立有利于快速、精确地确定特征基因与性能的关系,实现胶凝材料成分和性能的双向设计。本文从纳米胶凝材料的特征基因,micro-,和宏观视角。它总结了特征基因,分析各种尺度的表达参数,并总结了它们与机械性能的关系。在纳米尺度上,水合硅酸钙(C-S-H)被认为是最重要的特征基因,钙硅比是描述其结构的关键参数。在微观尺度上,孔隙结构和气泡系统是关键特征,具有孔隙率等参数,孔径分布,孔隙形状,空气含量,气泡间距系数直接影响抗冻性,渗透性,和抗压强度。在宏观尺度上,骨料是胶凝材料中最重要的组成部分。它的形状,棱角,表面纹理(纹理),破碎指数,和吸水率是影响氯离子渗透阻力等性能的主要特征,粘度,流动性,和力量。通过分析和绘制这些基因和属性在不同尺度之间的关系,本文提供了新的见解,并为有针对性地设计胶凝材料性能建立了参考框架。
    As an important gelling material, cementitious materials are widely used in civil engineering construction. Currently, research on these materials is conducted using experimental and numerical image processing methods, which enable the observation and analysis of structural changes and mechanical properties. These methods are instrumental in designing cementitious materials with specific performance criteria, despite their resource-intensive nature. The material genome approach represents a novel trend in material research and development. The establishment of a material gene database facilitates the rapid and precise determination of relationships between characteristic genes and performance, enabling the bidirectional design of cementitious materials\' composition and properties. This paper reviews the characteristic genes of cementitious materials from nano-, micro-, and macro-scale perspectives. It summarizes the characteristic genes, analyzes expression parameters at various scales, and concludes regarding their relationship to mechanical properties. On the nanoscale, calcium hydrated silicate (C-S-H) is identified as the most important characteristic gene, with the calcium-silicon ratio being the key parameter describing its structure. On the microscale, the pore structure and bubble system are key characteristics, with parameters such as porosity, pore size distribution, pore shape, air content, and the bubble spacing coefficient directly affecting properties like frost resistance, permeability, and compressive strength. On the macroscale, the aggregate emerges as the most important component of cementitious materials. Its shape, angularity, surface texture (grain), crushing index, and water absorption are the main characteristics influencing properties such as chloride ion penetration resistance, viscosity, fluidity, and strength. By analyzing and mapping the relationship between these genes and properties across different scales, this paper offers new insights and establishes a reference framework for the targeted design of cementitious material properties.
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  • 文章类型: Journal Article
    在这项研究中,用不同强度(5T和15T)的超高磁场(UMF)处理玉米淀粉(A型)和马铃薯淀粉(B型),通过测量其结构和流变特性的变化来研究其对UMF的敏感性。结果表明,A型淀粉的结晶度明显降低,在5T时达到最低20.01%。相比之下,B型淀粉的结晶度明显增加,在15吨时达到21.17%的峰值,伴随着更亮的极化十字和更完美的晶体结构。此外,B型淀粉表现出双螺旋含量的显著增加(从32.67%增加到42.07%),支化度(从1.96%到3.84%),和R1022/995(从0.803到0.519),与A型淀粉相比。B型淀粉也显示出更大的交联反应形成OCOR基团的倾向(从0%到6.81%),其焓变(ΔH)大幅增加(从19.28J/g增加到31.70J/g),表明热稳定性显著增强。此外,B型淀粉的平均流体动力学半径(Rh)降低更多,反映了凝胶强度的增加。这些发现表明B型淀粉比A型淀粉对UMF更敏感。这项研究提供了有关UMF处理对不同结晶淀粉的影响的基础数据,旨在探索其在食品和工业领域的潜在应用。
    In this study, maize starch (A-type) and potato starch (B-type) were treated with ultrahigh magnetic fields (UMF) of different intensities (5 T and 15 T) to investigate their sensitivity to UMF by measuring changes in their structure and rheological properties. The results indicate that the crystallinity of A-type starch significantly decreases, reaching a minimum of 20.01 % at 5 T. In contrast, the crystallinity of B-type starch significantly increases, peaking at 21.17 % at 15 T, accompanied by a brighter polarized cross and a more perfect crystal structure. Additionally, B-type starch exhibited a significant increase in double helix content (from 32.67 % to 42.07 %), branching degree (from 1.96 % to 3.84 %), and R1022/995 (from 0.803 to 0.519), compared to A-type starch. B-type starch also showed a greater propensity for cross-linking reactions forming OCOR groups (from 0 % to 6.81 %), and its enthalpy change (∆H) increased substantially (from 19.28 J/g to 31.70 J/g), indicating a marked enhancement in thermal stability. Furthermore, the average hydrodynamic radius (Rh) decreased more for B-type starch, reflecting an increase in gel strength. These findings demonstrate that B-type starch is more sensitive to UMF than A-type starch. This study provides foundational data on the effects of UMF treatment on different crystalline starches, aiming to explore its potential applications in food and industrial fields.
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  • 文章类型: Journal Article
    为克服铝热还原法制备的CuCr50合金中Cr2O3和Al2O3夹杂物问题,在本文中,提出了一种通过原位造渣强化金属渣分离的新方法。以Al和Al-Mg为还原剂,通过金属热还原制备CuCr50合金,和炉渣的物理性质,如粘度,密度,和表面张力,通过控制原料中造渣剂中CaO的比例进行调整,以实现炉渣与金属的良好分离。结果表明,随着CaO比例的增加,CaO和MgO耦合成渣,与Cr2O3和Al2O3结合在炉渣中形成CaCr2O4,MgCr2O4和CaAl4O7,从而降低了合金中杂质的含量。当RCaO/(CaO+Al2O3+MgO)=20%时,Cr含量在46.61%到47.09%之间,夹杂物占1.60%,Cr颗粒大小被细化到20微米,Cr球形晶体的数量占9.88%,电导率达到14.96MS/m,硬度达到100.23HB。热处理后,Cr相在合金中被细化,电导率从14.96MS/m增加到18.27MS/m,硬度从100.23HB增加到103.1HB。该方法有望为CuCr50触头材料的制备提供一种有效的方法。
    To overcome the problem of Cr2O3 and Al2O3 inclusions in CuCr50 alloy prepared by aluminothermic reduction method, in this paper, a novel methodology for strengthening metal-slag separation through in situ slagging is proposed. CuCr50 alloys were prepared by metallothermic reduction using Al and Al-Mg as reducing agents, and the physical properties of the slag, such as viscosity, density, and surface tension, were adjusted by controlling the proportion of CaO in the slagging agent in the raw material to achieve good separation of the slag-metal. The results show that with the ratio of CaO increased, CaO and MgO were coupled to make slag, which combined with Cr2O3 and Al2O3 to form CaCr2O4, MgCr2O4, and CaAl4O7 in the slag, thus reducing the content of impurities in the alloy. When RCaO/(CaO + Al2O3 + MgO) = 20%, the Cr content ranged from 46.61% to 47.09%, the inclusions accounted for 1.60%, the Cr particle size was refined to 20 µm, the number of Cr spherical crystals accounted for 9.88%, the conductivity reached 14.96 MS/m, and the hardness reached 100.23 HB. After heat treatment, the Cr phase was refined in the alloy, the conductivity increased from 14.96 MS/m to 18.27 MS/m, and the hardness increased from 100.23 HB to 103.1 HB. This method is expected to provide an effective method for the preparation of CuCr50 contact materials.
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  • 文章类型: Journal Article
    伤口愈合是世界范围内的主要挑战,几十年来,人们一直在研究可以促进伤口愈合的伤口敷料。天然生物基材料,如多糖和蛋白质,已广泛用于伤口敷料的开发。其中,大豆蛋白基材料由于其安全性而引起了广泛研究人员的兴趣,生物相容性,受控降解,以及与其他材料混合的能力。然而,对于这些基于大豆蛋白的伤口敷料缺乏评论。这项工作回顾了各种形式的大豆蛋白基伤口敷料,如水凝胶,电影,和其他人,它可以通过与合成或天然聚合物的物理/化学交联来制备。将检查大豆蛋白基材料在伤口愈合阶段的重要作用及其特性,比如他们的抗炎,抗氧化剂,促进血管生成,细胞生物相容性,自我修复能力,附着力,抗菌,和可调的机械性能。此外,提供了对大豆蛋白敷料市场前景和趋势的见解,阐明了大豆蛋白作为一种新型创伤修复材料的巨大发展潜力。
    Wound healing is a major challenge worldwide, and people have been researching wound dressings that can promote wound healing for decades. Natural biobased materials, such as polysaccharides and proteins, have been widely used in the development of wound dressings. Among them, soy protein-based materials have attracted the interest of a wide range of researchers due to their safety, biocompatibility, controlled degradation, and ability to be mixed with other materials. However, there has been a lack of comments on these soy protein-based wound dressings. This work reviews various forms of soy protein-based wound dressings, such as hydrogels, films, and others, which could be prepared through physical/chemical cross-linking with synthetic or natural polymers. The important role played by soy protein-based materials in the wound healing phase and their properties will be examined, such as their anti-inflammatory, antioxidant, angiogenesis-promoting, cellular biocompatibility, self-healing ability, adhesion, antimicrobial, and tunable mechanical properties. Additionally, insights into the market prospects and trends for soy protein dressings are provided, clarifying the enormous development potential of soy protein as a new type of wound repair material.
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  • 文章类型: Journal Article
    背景:慢性咳嗽影响约10%的普通成年人,损害生活质量的各个方面。
    目的:莱斯特咳嗽问卷的心理测量特性是什么?
    方法:PubMed的电子搜索,CINAHL,和ScienceDirect数据库从成立到2022年10月1日。所有全文文章,以法语或英语出版,旨在评估LCQ的内容有效性或心理测量特性。应用COSMIN偏差风险检查表评估其方法学质量和结果。结果通过改进的GRADE方法进行定性总结和评级。
    结果:纳入40项研究,涉及8,731名成年人,咳嗽或呼吸道疾病。慢性咳嗽(>8周)是最有代表性的。LCQ的总分与咳嗽对QoL的影响评估相关且可理解。原始的3因素模型显示出令人满意的模型拟合。对于总域和物理域得分发现了良好的收敛有效性。这些分数表现出良好的内部一致性和测试重测可靠性,注意到一些可变性,它们对变化有反应。最近估计的MID阈值分别为1.7和0.4的总分和域分数。研究的质量在全球范围内很差。
    结论:LCQ是评估咳嗽对QoL的个体内影响以及主要在短期临床试验中检测生活质量的巨大变化的有效结果。
    背景:该协议已在PROSPERO(CRD42XXXXX)注册。
    BACKGROUND: Chronic cough affects around 10 % of the general adult population, impairing all aspects of quality of life.
    OBJECTIVE: What are the Leicester Cough Questionnaire\'s psychometric properties?
    METHODS: Electronic searches of PubMed, CINAHL, and ScienceDirect databases were conducted from inception until October 1rst 2022. All full-text articles, published in French or English, aimed at evaluating the LCQ\'s content validity or psychometric properties were included. The COSMIN Risk of Bias checklist was applied to assess their methodological quality and results. Results were qualitatively summarised and rated by a modified GRADE approach.
    RESULTS: 40 studies were included accounting for 8731 adults, subject to cough or a respiratory condition. Chronic cough (>8 weeks) was the most represented. The LCQ\'s total score is relevant and comprehensible for the assessment of the impact of cough on QoL. The original 3-factor model showed a satisfactory model fit. Good convergent validity was found for the total and physical domain scores. These scores demonstrate good internal consistency and test retest reliability, with some variability noted and they are responsive to change. Recent estimates of MID thresholds were 1.7 and 0.4 for total and domain scores respectively. The quality of the studies is globally poor.
    CONCLUSIONS: The LCQ is a valid outcome to assess the intra-individual impact of cough on QoL and to detect large changes in quality of life mainly in a short-term clinical trial setting.
    BACKGROUND: The protocol was registered with PROSPERO (CRD42022355191).
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  • 文章类型: Journal Article
    木质素基碳纳米材料提供了几个优点,包括生物降解性,生物相容性,高比表面积,易于功能化,低毒性,和成本效益。这些材料在生化传感应用中显示出希望,特别是在金属离子的检测中,有机化合物,和人类生物信号。可以采用各种方法来合成具有从0D到3D的不同尺寸的碳纳米材料,导致不同的结构和物理化学性质。本研究概述了多维(0-3D)木质素基碳纳米材料的制备技术和特性,例如碳点(CD),碳纳米管(CNTs),石墨烯,石墨烯和碳气凝胶(CAs)。此外,对这些材料的传感能力进行了比较和总结,随后讨论了传感器发展的潜在挑战和未来前景。
    Lignin-based carbon nanomaterials offer several advantages, including biodegradability, biocompatibility, high specific surface area, ease of functionalization, low toxicity, and cost-effectiveness. These materials show promise in biochemical sensing applications, particularly in the detection of metal ions, organic compounds, and human biosignals. Various methods can be employed to synthesize carbon nanomaterials with different dimensions ranging from 0D to 3D, resulting in diverse structures and physicochemical properties. This study provides an overview of the preparation techniques and characteristics of multidimensional (0-3D) lignin-based carbon nanomaterials, such as carbon dots (CDs), carbon nanotubes (CNTs), graphene, and carbon aerogels (CAs). Additionally, the sensing capabilities of these materials are compared and summarized, followed by a discussion on the potential challenges and future prospects in sensor development.
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  • 文章类型: Journal Article
    这篇综述旨在全面记录生物合成,分类,属性,以及Weissella属菌株产生的细菌素的应用,特别强调它们在食品保存方面的潜在好处,人类健康,和动物生产力。乳酸菌(LAB)是一类以其在食品发酵中的有益作用而闻名的微生物,益生菌,和人类健康。LAB的一个值得注意的特性是它们可以合成被称为细菌素的抗微生物肽,其也表现出对密切相关的细菌和其他细菌的抗微生物作用。Weissellaspp产生的细菌素。已知对几种致病菌表现出抗菌活性,包括食物腐败物种,使它们在食品保存和食品安全方面的潜在应用非常宝贵。重要的是,它们为人类提供了显著的健康益处,包括对抗感染,减少炎症,和调节肠道微生物群。除了它们在食品发酵和益生菌中的应用外,Weissella细菌素在家禽生产中显示出广阔的前景,processing,提高动物生产力。未来的研究应探索Weissella细菌素在创新食品安全措施和医学应用中的应用。强调它们对抗抗生素抗性病原体的潜力,增强肠道菌群组成和功能,并与现有的抗菌疗法协同作用。
    This review aims to comprehensively chronicle the biosynthesis, classification, properties, and applications of bacteriocins produced by Weissella genus strains, particularly emphasizing their potential benefits in food preservation, human health, and animal productivity. Lactic Acid Bacteria (LAB) are a class of microorganisms well-known for their beneficial role in food fermentation, probiotics, and human health. A notable property of LAB is that they can synthesize antimicrobial peptides known as bacteriocins that exhibit antimicrobial action against both closely related and other bacteria as well. Bacteriocins produced by Weissella spp. are known to exhibit antimicrobial activity against several pathogenic bacteria including food spoilage species, making them highly invaluable for potential application in food preservation and food safety. Importantly, they provide significant health benefits to humans, including combating infections, reducing inflammation, and modulating the gut microbiota. In addition to their applications in food fermentation and probiotics, Weissella bacteriocins show promising prospects in poultry production, processing, and improving animal productivity. Future research should explore the utilization of Weissella bacteriocins in innovative food safety measures and medical applications, emphasizing their potential to combat antibiotic-resistant pathogens, enhance gut microbiota composition and function, and synergize with existing antimicrobial therapies.
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  • 文章类型: Journal Article
    三元乙丙橡胶(EPDM)具有较高的耐热性和耐化学性,是一种广泛应用于工业和商业的合成橡胶。纳米技术使纳米材料能够结合到聚合物基质中,保持其灵活性和构象,允许它们实现以前无法实现的属性,如改善拉伸和耐化学性。在这项工作中,我们总结了不同纳米结构对机械的影响,热,EPDM基材料的电性能,以跟上当前的研究并支持未来对合成橡胶纳米复合材料的研究。
    Ethylene propylene diene monomer (EPDM) is a synthetic rubber widely used in industry and commerce due to its high thermal and chemical resistance. Nanotechnology has enabled the incorporation of nanomaterials into polymeric matrixes that maintain their flexibility and conformation, allowing them to achieve properties previously unattainable, such as improved tensile and chemical resistance. In this work, we summarize the influence of different nanostructures on the mechanical, thermal, and electrical properties of EPDM-based materials to keep up with current research and support future research into synthetic rubber nanocomposites.
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