anisotropy

各向异性
  • 文章类型: Journal Article
    冷却模具单元操作的可扩展性对于降低高水分肉类类似物(HMMA)的制造成本至关重要。但目前还不清楚什么标准是重要的。由两个冷却模具横截面几何形状(高而窄或短而宽)组成的实验,采用两种生产率(2.7或4.5kg/hr)和4种冷却介质入口温度(36、48、60和72°C)来研究它们对产品质地的影响,各向异性,和挤压系统参数。沿模具进行全面的温度测量以观察产品温度梯度并量化与冷却相关的能量平衡。发现组织硬度与轴向温度梯度呈正相关(p<0.05)。而各向异性与轴向温度梯度和模具高度呈正负关系,分别为(p<0.05)。发现挤出机马达扭矩和模具入口压力是冷却介质入口温度和施加到模具中的材料的表观牛顿剪切速率的函数(p<0.05)。能量平衡表明,增强的各向异性与更多的放热原位相变有关,这是由产品配方和应用模具条件控制。可能有3个与控制HMMA产品质量最相关的可扩展变量:2个临界相变温度,和轴向产品温度梯度。因此,按比例放大HMMA冷却模具将需要平衡远离产品的热传递速率,使得可以按比例保持最佳产品温度分布。
    Scalability of the cooling die unit operation is critical to lowering the manufacturing cost of high moisture meat analogs(HMMA), but it is unclear what scale-up criteria are important. An experiment consisting of two cooling die cross-section geometries (tall and narrow or short and wide), two production rates (2.7 or 4.5 kg/hr) and 4 cooling media inlet temperatures (36, 48, 60, and 72 °C) was employed to study their effect on product texture, anisotropy, and extrusion system parameters. Comprehensive temperature measurements were made along the dies to observe the product temperature gradient and to quantify the energy balance associated with cooling. It was found that textural hardness had a positive relationship with axial temperature gradient (p < 0.05), while anisotropy had a negative and positive relationship with axial temperature gradient and die height, respectively (p < 0.05). Extruder motor torque and die inlet pressure were found to be functions of the cooling media inlet temperature and apparent Newtonian shear rate applied to the material in the die (p < 0.05). The energy balance indicated that enhanced anisotropy is associated with more exothermic in-situ phase changes, which are controlled by the product formulation and applied die conditions. There are likely 3 scalable variables most relevant to controlling the HMMA product quality: 2 critical phase transition temperatures, and the axial product temperature gradient. Therefore, scaling up HMMA cooling dies will require balancing the heat transfer rate away from the product such that an optimal product temperature profile can be maintained at scale.
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  • 文章类型: Journal Article
    这里,我们研究了短链直链淀粉(SCAs)和棕榈酸(PA)的络合,用作改变颗粒生长的选择性和方向性的聚合物结构单元。这种改变会影响粒子的形状各向异性,扩大他们的应用由于增加的表面积。通过改变PA的浓度,我们能够制造球形,马卡龙,和圆盘形颗粒,证明PA充当结构导向剂。我们进一步说明了自组装过程中PA-SCA包合物之间的横向和纵向堆积动力学,导致各向异性。透射电子显微镜(TEM)和扫描电子显微镜(SEM)揭示了棕榈酸-短链直链淀粉颗粒(PA-SCAP)与短链直链淀粉颗粒(SCAP)的初始和最终形态之间的结构差异。使用核磁共振(NMR)和粉末X射线衍射(XRD)分析确认各向异性颗粒中PA-SCA包合物的存在。
    Here, we investigated the complexation of short chain amylose (SCAs) and palmitic acid (PA), serving as polymeric building blocks that alter the selectivity and directionality of particle growth. This alteration affects the shape anisotropy of the particles, broadening their applications due to the increased surface area. By modifying the concentration of PA, we were able to make spherical, macaron, and disc-shaped particles, demonstrating that PA acts as a structure-directing agent. We further illustrated the lateral and longitudinal stacking kinetics between PA-SCA inclusion complexes during self-assembly, leading to anisotropy. Transmission electron microscope (TEM) and scanning electron microscope (SEM) revealed the structural difference between the initial and final morphologies of palmitic acid-short chain amylose particles (PA-SCAPs) compared to those of short-chain amylose particle (SCAPs). The presence of PA-SCA inclusion complex in the anisotropic particles was confirmed using nuclear magnetic resonance (NMR) and powder x-ray diffraction (XRD) analysis.
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  • 文章类型: Journal Article
    对8-苯胺基-1-萘磺酸盐(ANS)荧光探针的吸收和荧光性质进行研究,以(i)验证其分类为疏水探针的有效性和(ii)评估蛋白质结合时ANS荧光增强的解释的可靠性,作为蛋白质分子上存在疏水结合位点的证据。我们观察到在亲水介质中ANS荧光的增强:DMSO,聚乙二醇(PEG400)和甘油的ANS复合物与球状蛋白质的特征值,PEG400和与牛血清白蛋白的复合物中的所有ANS荧光特性(各向异性除外)相同。我们观察到,在两亲性十六烷基三甲基铵阳离子存在下,由于与ANS形成1:1络合物,在水性介质中ANS荧光具有非零各向异性。水分子猝灭ANS的荧光。在存在荧光增强剂的情况下,水性介质中ANS荧光的增强是由于它们阻止水分子进入靠近激发的ANS分子的区域。这对荧光至关重要。
    A study on the absorption and fluorescence properties of the 8-anilino-1-naphthalenesulfonate (ANS) fluorescent probe was performed in order to (i) verify the validity of its classification as hydrophobic probe and (ii) to assess the reliability of the interpretation of the ANS fluorescence enhancement upon protein binding as the evidence for the existence of hydrophobic binding sites on the protein molecules. We observed an enhancement of the ANS fluorescence in hydrophilic media: DMSO, polyethylene glycol (PEG400) and glycerol to the values characteristic of ANS complexes with globular proteins, and all ANS fluorescence characteristics (except anisotropy) in PEG400 and in complex with bovine serum albumin are identical. We observed an increase in the ANS fluorescence with a nonzero anisotropy in an aqueous medium in the presence of an amphiphilic cetyltrimethylammonium cation as a result of the formation of the 1:1 complex with ANS. Water molecules quench the fluorescence of ANS. The enhancement of the ANS fluorescence in aqueous media in the presence of fluorescence enhancers is accounted for by their blocking the access of water molecules to the region close to the excited ANS molecule, which is critical for the fluorescence.
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  • 文章类型: Journal Article
    大自然为我们设计仿生功能曲面提供了丰富的灵感。许多类型的植物叶子具有特殊的润湿性,各向异性,和附着力广泛用于许多工程应用。受润湿性的启发,各向异性,和黏土叶的粘附,使用激光扫描和化学修饰相结合的简便方法成功制备了indocalamus叶片的仿生上下表面(BUS和BLSs)。结果表明,BUSs和BLSs获得了与indocalamus叶的上表面和下表面相似的结构特征,并表现出增强和更可控的润湿性,各向异性,和附着力。更重要的是,我们对润湿性进行了详细的比较分析,各向异性,BUSs和BLSs之间的附着力。最后,还探索了BUS和BLS的相应潜在应用,包括自我清洁,液体操纵,和雾的收集,从而扩大其实际效用。我们相信,这项研究可以促进新型生物模型的研究,并为多功能仿生表面的发展提供重要的见解。
    Nature provides us with a wealth of inspiration for the design of bionic functional surfaces. Numerous types of plant leaves with exceptional wettability, anisotropy, and adhesion are extensively employed in many engineering applications. Inspired by the wettability, anisotropy, and adhesion of indocalamus leaves, bionic upper and lower surfaces (BUSs and BLSs) of the indocalamus leaf were successfully prepared using a facile approach combining laser scanning and chemical modification. The results demonstrated the BUSs and BLSs obtained similar structural features to the upper and lower surfaces of the indocalamus leaf and exhibited enhanced and more-controllable wettability, anisotropy, and adhesion. More importantly, we conducted a detailed comparative analysis of the wettability, anisotropy, and adhesion between BUSs and BLSs. Finally, BUSs and BLSs were also explored for the corresponding potential applications, including self-cleaning, liquid manipulation, and fog collection, thereby broadening their practical utility. We believe that this study can contribute to the enrichment of the research on novel biological models and provide significant insights into the development of multifunctional bionic surfaces.
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  • 文章类型: Journal Article
    利用各向异性Drucker模型研究了5754-H111铝合金在不同应力条件下三种塑性工作的屈服行为。发现当塑性工作为30MPa时,各向异性Drucker模型具有最准确的预测。将Hill48和Yld91模型与Drucker模型进行比较,结果表明,各向异性Drucker和Yld91模型均能准确预测合金的屈服行为。在AFR下进行圆柱拉伸有限元分析,但是无法准确预测耳部外观的位置和高度。各向异性Drucker模型用于预测非AFR下的耳部行为,可以准确预测耳部现象。使用三种不同的屈服函数组合进行了数值模拟:各向异性屈服函数和各向异性塑性势函数(AYAPP),各向异性屈服函数和各向同性塑性势函数(AYIPP),以及各向同性屈服函数和各向异性塑性势函数(IYAPP)。结论是,塑性势函数对预测抽穗行为的影响比屈服函数更重要。
    The yield behavior of aluminum alloy 5754-H111 under different stress conditions for three kinds of plastic work is studied using an anisotropic Drucker model. It is found that when the plastic work is 30 MPa, the anisotropic Drucker model has the most accurate prediction. Comparing the Hill48 and Yld91 models with the Drucker model, the results show that both the anisotropic Drucker and Yld91 models can accurately predict the yield behavior of the alloy. Cylinder drawing finite element analysis is performed under the AFR, but it is not possible to accurately predict the position and height of earing appearance. The anisotropic Drucker model is used to predict the earing behavior under the non-AFR, which can accurately predict the earing phenomenon. Numerical simulation is conducted using three different combinations of yield functions: the anisotropic yield function and the anisotropic plastic potential function (AYAPP), the anisotropic yield function and the isotropic plastic potential function (AYIPP), and the isotropic yield function and the anisotropic plastic potential function (IYAPP). It is concluded that the influence of the plastic potential function on predicting earing behavior is more critical than that of the yield function.
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  • 文章类型: Journal Article
    增材制造(AM)是一种逐层构建零件的技术。在过去的十年里,金属增材制造(AM)技术发展迅速,形成了完整的产业链。AM金属零件在众多行业中使用,包括生物医学,航空航天,汽车,海洋,和离岸。与现有制造工艺相比,可以在更大程度上改进部件的设计,这可以显著提高性能。已经报道了增材制造金属材料各向异性的研究,他们描述了使用增材制造工艺制备不同金属材料的优点和缺点;然而,在同一篇文章中,很少有深入而全面的研究总结不同类型增材制造金属材料的微观结构和力学性能。本文首先概述了增材制造过程之间的复杂关系,微观结构,和金属属性。然后解释了粉末床融合(PBF)和定向能量沉积(DED)的基本原理。接着描述了增材制造过程中的熔池和热影响区,并分析了它们对成形零件微观结构的影响。随后,增材制造钛合金的机械性能和典型的微观结构,不锈钢,镁铝合金,和高温合金,随着它们的各向异性,进行了总结和介绍。总结表明,导致金属AM零件机械性能各向异性的因素是其独特的微观结构特征或制造缺陷。该各向异性可以通过后热处理来改善。最后,介绍了金属AM各向异性的最新研究。
    Additive manufacturing (AM) is a technology that builds parts layer by layer. Over the past decade, metal additive manufacturing (AM) technology has developed rapidly to form a complete industry chain. AM metal parts are employed in a multitude of industries, including biomedical, aerospace, automotive, marine, and offshore. The design of components can be improved to a greater extent than is possible with existing manufacturing processes, which can result in a significant enhancement of performance. Studies on the anisotropy of additively manufactured metallic materials have been reported, and they describe the advantages and disadvantages of preparing different metallic materials using additive manufacturing processes; however, there are few in-depth and comprehensive studies that summarize the microstructural and mechanical properties of different types of additively manufactured metallic materials in the same article. This paper begins by outlining the intricate relationship between the additive manufacturing process, microstructure, and metal properties. It then explains the fundamental principles of powder bed fusion (PBF) and directed energy deposition (DED). It goes on to describe the molten pool and heat-affected zone in the additive manufacturing process and analyzes their effects on the microstructure of the formed parts. Subsequently, the mechanical properties and typical microstructures of additively manufactured titanium alloys, stainless steel, magnesium-aluminum alloys, and high-temperature alloys, along with their anisotropy, are summarized and presented. The summary indicates that the factors leading to the anisotropy of the mechanical properties of metallic AM parts are either their unique microstructural features or manufacturing defects. This anisotropy can be improved by post-heat treatment. Finally, the most recent research on the subject of metal AM anisotropy is presented.
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  • 文章类型: Journal Article
    骨折的二次愈合需要应用适当的固定器。总的来说,主要使用钢或钛设备。然而,近年来,由于高强度重量比和其他优点,复合结构作为一种有吸引力的替代品出现,例如,射线可透性。根据食品和药物管理局(FDA)唯一允许植入人体的单向增强复合材料是碳纤维(CF)增强的聚醚醚酮(PEEK)。在这项工作中,在有限元方法的框架下,研究了用CF/PEEK板组装的交叉和角度铺层结构的长骨的愈合过程。通过使用基于Prendergast理论的机械调节模型来模拟愈合。细胞转化由八面体剪切应变和间质液速度决定。该过程迭代地运行,假设每天单个负载周期。断裂受到轴向力和横向力的作用。在计算中,使用Abaqus程序。表明,CF/PEEK复合材料的角度层合方案似乎为软骨call转变为骨组织提供了更好的条件。
    Secondary healing of fractured bones requires an application of an appropriate fixator. In general, steel or titanium devices are used mostly. However, in recent years, composite structures arise as an attractive alternative due to high strength to weight ratio and other advantages like, for example, radiolucency. According to Food and Drug Administration (FDA), the only unidirectionally reinforced composite allowed to be implanted in human bodies is carbon fiber (CF)-reinforced poly-ether-ether-ketone (PEEK). In this work, the healing process of long bone assembled with CF/PEEK plates with cross- and angle-ply lay-up configurations is studied in the framework of finite element method. The healing is simulated by making use of the mechanoregulation model basing on the Prendergast theory. Cells transformation is determined by the octahedral shear strain and interstitial fluid velocity. The process runs iteratively assuming single load cycle each day. The fracture is subjected to axial and transverse forces. In the computations, the Abaqus program is used. It is shown that the angle-ply lamination scheme of CF/PEEK composite seems to provide better conditions for the transformation of the soft callus into the bone tissue.
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  • 文章类型: Journal Article
    长老会,或年龄相关的听力损失,影响老年人和狗,显著损害他们的社交互动和认知。在人类中,老年性耳聋涉及周围和中枢听觉系统的变化,中央变化可能独立发生。虽然狗的外周性老年性耳聋是有据可查的,关于中央变化的研究仍然有限。扩散张量成像(DTI)是检测和量化脑白质异常的有用工具。本研究使用DTI探索老年犬的中枢听觉通路,旨在提高我们对犬类老年性耳聋的认识。招募超过预期寿命75%的狗,并通过脑干听觉诱发反应测试进行筛查,以选择没有严重周围听力损失的狗。使用3T磁共振扫描仪扫描16只符合标准的狗。基于轨迹的空间统计用于分析中枢听觉通路。在声辐射中发现分数寿命与分数各向异性之间存在显着负相关。提示中枢听觉系统中与年龄相关的白质变化。这些变化,在没有严重周围听力损失的狗中观察到,可能有助于中央长老会的发展。
    Presbycusis, or age-related hearing loss, affects both elderly humans and dogs, significantly impairing their social interactions and cognition. In humans, presbycusis involves changes in peripheral and central auditory systems, with central changes potentially occurring independently. While peripheral presbycusis in dogs is well-documented, research on central changes remains limited. Diffusion tensor imaging (DTI) is a useful tool for detecting and quantifying cerebral white matter abnormalities. This study used DTI to explore the central auditory pathway of senior dogs, aiming to enhance our understanding of canine presbycusis. Dogs beyond 75% of their expected lifespan were recruited and screened with brainstem auditory evoked response testing to select dogs without severe peripheral hearing loss. Sixteen dogs meeting the criteria were scanned using a 3 T magnetic resonance scanner. Tract-based spatial statistics was used to analyze the central auditory pathways. A significant negative correlation between fractional lifespan and fractional anisotropy was found in the acoustic radiation, suggesting age-related white matter changes in the central auditory system. These changes, observed in dogs without severe peripheral hearing loss, may contribute to central presbycusis development.
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  • 文章类型: Journal Article
    膨胀收缩特性土壤在干燥过程中表现出很高的开裂敏感性,这对各种地质灾害构成了重大风险。其中,干燥收缩的发生是开裂现象的先决条件。因此,了解与干燥收缩机理相关的具体特征至关重要。为了研究膨胀收缩特征土壤的干燥收缩行为,对红黏土和膨胀土的长条样进行了一系列干缩试验。利用三维数字图像相关(DIC)技术,表面位移,应变,并获得了土壤样品在干燥过程中的各向异性收缩率,分析了尺寸效应对胀缩特征土干燥收缩的影响。研究结果如下:土样在X和Y方向上的位移发展可分为两个阶段:线性生长阶段和稳定位移阶段。在Z方向,土面变形可分为三个阶段:土面拱,垂直收缩,和收缩稳定。胀缩特征土的干缩表现出各向异性,垂直收缩率最大,其次是纵向,然后是横向。此外,土壤样品收缩表现出尺寸效应,其中在所有方向上的收缩率随着样品宽度和厚度的增加而增加。在干燥收缩过程中,土壤表面的应力状态从初始拉伸应变演变为随后的压缩应变。土样内不同位置和时间的应变不均匀,导致样品收缩的不均匀性和各向异性。该研究为研究胀缩特性土的开裂机理提供了重要的见解,并为相关实验室实验提供了有价值的参考。这将有助于更好地预测和控制由胀缩特征土壤干燥收缩引起的地质灾害。
    Swell-shrink characteristic soils exhibit a high susceptibility to cracking during the drying process, which poses a significant risk of various geological disasters. Among these, the occurrence of drying shrinkage acts as a prerequisite for the cracking phenomenon. Therefore, it is of utmost importance to comprehend the specific characteristics associated with the drying shrinkage mechanism. To investigate the drying shrinkage behavior of swell-shrink characteristic soils, a series of drying shrinkage experiments were conducted on long strip samples of red clay and expansive soil. Utilizing three-dimensional digital image correlation (DIC) technology, the surface displacement, strain, and anisotropic shrinkage rates of the soil samples during the drying process were obtained, and the size effect on the drying shrinkage of swell-shrink characteristic soil were analyzed. The research findings are as follows: The displacement development of the soil samples in the X and Y directions can be divided into two stages: a linear growth stage and a stable displacement stage. In the Z direction, the soil surface deformation can be divided into three stages: soil surface arching, vertical shrinkage, and shrinkage stabilization. The drying shrinkage of swell-shrink characteristic soil exhibits anisotropy, with the vertical shrinkage rate being the largest, followed by the longitudinal and then the transverse directions. Additionally, the soil sample shrinkage exhibits a size effect, whereby the shrinkage rates in all directions increase with increasing sample width and thickness. During the drying shrinkage process, the stress state on the soil surface evolves from initial tensile strain to subsequent compressive strain. The strain at different positions and times within the soil sample is not uniform, resulting in the non-uniformity and anisotropy of the sample shrinkage. This study provides important insights into the cracking mechanism of swell-shrink characteristic soils and serves as a valuable reference for related laboratory experiments, which will contribute to better prediction and control the geological hazards caused by the drying shrinkage of swell-shrink characteristic soils.
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  • 文章类型: Journal Article
    这项研究探讨了未开发的氢氧化锂(LiOH)作为相变材料用于热能存储的潜力。通过克服与液态LiOH泄漏相关的挑战,我们在实验室规模的实验中成功地热循环了LiOH,并观察其稳定性(>500个热循环),没有化学分解。到目前为止,此步骤从未执行过。其固体到液体的可逆转变温度和相关的凝固/熔化焓值已得到验证。然后,LiOH热性能的第一个实验表征显示出其热容的意外值,热导率和扩散系数,与文献中的少数相矛盾。这为LiOH的显热和潜热存储应用开辟了道路,如通过增加的循环效率潜力的热能储存系统,如果基于其能量储存容量显示;高达六倍的体积能量密度相比,传统的太阳能盐基系统用于太阳能塔式电厂(4.5GJ/m3vs.0.76GJ/m3超过1000个热循环)。此外,我们观察到在加热过程中出现不一致的软化现象,但这可能是其优异的熔融性能以及与其他原料化学品的相互作用。这种新见解无疑有助于合成另一种有前途的储热材料的潜在机制:包晶化合物Li4Br(OH)3。这项开创性的工作表明,LiOH是一种有前途的超紧凑型热能储存材料,用于填补从当前到下一代太阳能发电厂的中间空白。尽管其大规模应用需要进一步调查以实现经济可行性。
    This study explores the potential of untapped lithium hydroxide (LiOH) as a phase change material for thermal energy storage. By overcoming the challenges associated with the liquid LiOH leakage, we successfully thermal-cycled LiOH in a laboratory scale experimentation, and observed its stability (>500 thermal cycles), without chemical decomposition. This step has never been performed to date. Its solid-to-liquid reversible transitions temperatures and related solidification/melting enthalpies values have been verified. Then, the first experimental characterization of LiOH\'s thermal properties shows unexpected values for its heat capacity, thermal conductivity and diffusivity, in contradiction with the few ones available in literature. This opens avenues for LiOH\'s applications for the storage of sensible and latent heat, as shown through the increased cycle efficiency potential of a thermal energy storage system if based on its energy storage capacity; up to six times more volumetric energy density compared to traditional Solar Salt-based systems used in the solar tower plant (4.5 GJ/m3 vs. 0.76 GJ/m3 over 1000 thermal cycles). Additionally, we observed a softening phenomenon that occurs inconsistently during heating, but which may account for its excellent melting properties and the interplay with other raw chemicals. This new insight contributes certainly to the underlying mechanisms in the synthesis of another promising heat storage material in development: the peritectic compound Li4Br(OH)3. This pioneering work suggests LiOH as a promising ultra-compact thermal energy storage material for filling the intermediary gap from current to next-generation solar power plants, although its large-scale application requires further investigation to achieve economic viability.
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