anisotropy

各向异性
  • 文章类型: Journal Article
    3D打印聚合物或金属可以实现复杂的结构,同时缺乏多功能性能。聚合物和金属的组合印刷是期望的且具有挑战性的,因为它们在熔点温度中不可克服的失配。这里,一种新型的体积金属化3D打印聚合物复合材料(VMPC),具有双连续相,用于实现耦合的结构和功能,据报道,通过将低熔点金属(LM)填充到可控的多孔结构中来制备。基于真空辅助低压条件,LM受大气压力作用引导,克服表面张力沿印刷聚合物孔通道扩散,使多孔结构的完全填充饱和,以增强拉伸强度(高达35.41MPa),热导率(高达25.29Wm-1K-1)和电导率(>106Sm-1)。设计的3D打印微结构定向可以实现力学中的协同各向异性(1.67),热(27.2),和电导率(>1012)。VMPC多功能演示,包括具有高强度的定制3D电子产品,电磁波导传输和信号放大,芯片温度控制的散热装置,和用于热电发电机光-热-电能量转换的存储组件。
    3D printing polymer or metal can achieve complicated structures while lacking multifunctional performance. Combined printing of polymer and metal is desirable and challenging due to their insurmountable mismatch in melting-point temperatures. Here, a novel volume-metallization 3D-printed polymer composite (VMPC) with bicontinuous phases for enabling coupled structure and function, which are prepared by infilling low-melting-point metal (LM) to controllable porous configuration is reported. Based on vacuum-assisted low-pressure conditions, LM is guided by atmospheric pressure action and overcomes surface tension to spread along the printed polymer pore channel, enabling the complete filling saturation of porous structures for enhanced tensile strength (up to 35.41 MPa), thermal (up to 25.29 Wm-1K-1) and electrical (>106 S m-1) conductivities. The designed 3D-printed microstructure-oriented can achieve synergistic anisotropy in mechanics (1.67), thermal (27.2), and electrical (>1012) conductivities. VMPC multifunction is demonstrated, including customized 3D electronics with elevated strength, electromagnetic wave-guided transport and signal amplification, heat dissipation device for chip temperature control, and storage components for thermoelectric generator energy conversion with light-heat-electricity.
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  • 文章类型: Journal Article
    不同厚度的柔性石墨箔(S=282±5μm,M=494±7μm,L=746±8μm),使用硝酸盐法获得的初始密度为0.70g/cm3。研究了这些箔的比电导率和热导率。随着密度从0.70g/cm3增加到1.75g/cm3,由于石墨箔的轧制,比电导率从69kS/m增加到192kS/m,热导率从109增加到326W/(m·K)。研究表明,电导率和各向异性取决于形状,定位,和热膨胀石墨(TEG)介观颗粒的接触面积(介观结构因子),和纳米微晶的晶体结构(纳米结构因子)。提出的细观结构模型解释了这些增加,密度更大的箔片显示为细长的,狭窄的TEG颗粒和更大的接触面积,由电子显微镜结果证实。对于200和750μm厚的石墨箔,密度增加导致更大的相干散射区域,可能是由于石墨介孔颗粒在机械作用下的旋转,而密度>1.7g/cm3的较薄的箔(<200μm)显示出增加的塑性变形,由相干散射区域尺寸的急剧减小表示。这从取向差角度随密度增加而减小也是明显的。与横向(TD)相比,沿轧制方向轧制减小的纳米微晶取向角(对于1.75g/cm3密度ΔMA=1.2°(S),2.6°(M),和2.4°(L)),解释了在轧制石墨箔的电气和机械性能中观察到的各向异性。X射线分析使用Kearns参数证实了优选的纳米微晶取向和各向异性系数(A),与实验测量结果吻合良好(对于L系列箔,计算为:A0.70=1.05,A1.30=1.10和A1.75=1.16)。这些计算值与比电导率的实验测量值非常吻合,其中各向异性系数从1.00变化到1.16,机械性能从0.98变化到1.13。
    Flexible graphite foils with varying thicknesses (S = 282 ± 5 μm, M = 494 ± 7 μm, L = 746 ± 8 μm) and an initial density of 0.70 g/cm3 were obtained using the nitrate method. The specific electrical and thermal conductivity of these foils were investigated. As the density increased from 0.70 g/cm3 to 1.75 g/cm3, the specific electrical conductivity increased from 69 to 192 kS/m and the thermal conductivity increased from 109 to 326 W/(m·K) due to the rolling of graphite foils. The study showed that conductivity and anisotropy depend on the shape, orientation, and contact area of thermally expanded graphite (TEG) mesoparticles (mesostructural factor), and the crystal structure of nanocrystallites (nanostructural factor). A proposed mesostructural model explained these increases, with denser foils showing elongated, narrowed TEG particles and larger contact areas, confirmed by electron microscopy results. For graphite foils 200 and 750 μm thick, increased density led to a larger coherent scattering region, likely due to the rotation of graphite mesoparticles under mechanical action, while thinner foils (<200 μm) with densities > 1.7 g/cm3 showed increased plastic deformation, indicated by a sharp reduction in the coherent scattering region size. This was also evident from the decrease in misorientation angles with increasing density. Rolling reduced nanocrystallite misorientation angles along the rolling direction compared to the transverse direction (TD) (for 1.75 g/cm3 density ΔMA = 1.2° (S), 2.6° (M), and 2.4° (L)), explaining the observed anisotropy in the electrical and mechanical properties of the rolled graphite foils. X-ray analysis confirmed the preferred nanocrystallite orientation and anisotropy coefficients (A) using Kearns parameters, which aligned well with experimental measurements (for L series foils calculated as: A0.70 = 1.05, A1.30 = 1.10, and A1.75 = 1.16). These calculated values corresponded well with the experimental measurements of specific electrical conductivity, where the anisotropy coefficient changed from 1.00 to 1.16 and mechanical properties varied from 0.98 to 1.13.
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  • 文章类型: Journal Article
    研究了钛(Ti)掺杂对二氧化钒(VO2)光学性能的影响,一种以接近室温的金属到绝缘体转变(MIT)而闻名的材料。通过将Ti掺入到VO2的晶格中,我们的目标是揭示其物理性质的变化,对于增强其在智能设备中的应用至关重要。利用偏振红外显微光谱,我们检查了从远红外到可见光谱范围的不同晶相(导电金红石相和绝缘单斜相M1和M2)中不同Ti浓度(x=0.059,x=0.082和x=0.187)的TixV1-xO2单晶。我们的发现表明,Ti掺杂显着影响声子光谱,引入不归因于纯VO2或TiO2的吸收峰。这在沿晶体生长轴的极化中尤其值得注意,主要在x=0.187样本中。此外,我们证明了电子对金属相中的光学电导率的贡献表现出强烈的各向异性,沿c轴高于a-b平面。这种各向异性,加上随着掺杂的增加,区域中心红外有源声子模式逐渐变宽,强调了掺杂VO2中结构动力学和电子动力学之间复杂的相互作用。我们的结果强调了Ti掺杂在微调VO2的电子和热致变色性能中的潜力,为其在光电设备和技术中的增强应用铺平了道路。
    This study delves into the effects of titanium (Ti) doping on the optical properties of vanadium dioxide (VO2), a material well known for its metal-to-insulator transition (MIT) near room temperature. By incorporating Ti into VO2\'s crystal lattice, we aim to uncover the resultant changes in its physical properties, crucial for enhancing its application in smart devices. Utilizing polarized infrared micro-spectroscopy, we examined TixV1-xO2 single crystals with varying Ti concentrations (x = 0.059, x = 0.082, and x = 0.187) across different crystal phases (the conductive rutile phase and insulating monoclinic phases M1 and M2) from the far-infrared to the visible spectral range. Our findings reveal that Ti doping significantly influences the phononic spectra, introducing absorption peaks not attributed to pure VO2 or TiO2. This is especially notable with polarization along the crystal growth axis, mainly in the x = 0.187 sample. Furthermore, we demonstrate that the electronic contribution to optical conductivity in the metallic phase exhibits strong anisotropy, higher along the c axis than the a-b plane. This anisotropy, coupled with the progressive broadening of the zone center infrared active phonon modes with increasing doping, highlights the complex interplay between structural and electronic dynamics in doped VO2. Our results underscore the potential of Ti doping in fine-tuning VO2\'s electronic and thermochromic properties, paving the way for its enhanced application in optoelectronic devices and technologies.
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  • 文章类型: Systematic Review
    神经系统疾病在早产(PT)出生的个体中很常见。使用基于束的空间统计(TBSS)的扩散张量成像(DTI)研究可有效检测大脑中的微结构白质(WM)异常。我们进行了这项系统评价,以整合TBSS研究的结果,以确定PT出生个体中最一致的WM改变。
    PubMed,Embase,搜索了WebofScience和ScienceDirect。截至2022年10月,对PT出生个体使用TBSS的DTI研究进行了筛选。系统评价包括报告立体定向空间中整个大脑FA值变化的研究,三个坐标(x,y,z),根据基于种子的d映射方法。
    搜索策略确定了17项符合我们纳入标准的研究,共分析了911名PT出生个体和563名匹配对照.在17项研究中,八个是献给650名成年人的,5至411名儿童和4至413名婴儿。10项研究招募了812名早产的人(GA<29周),6项研究招募了386名中度早产个体(GA=29-32周),1项研究招募了276名早产晚期个体(GA>32周).这项对包括388名个体的六项研究的荟萃分析强调了四个大脑区域,其中PT组的各向异性分数(FA)低于足月出生的人。定量荟萃分析发现,最稳健的WM改变位于call体(CC)中,双侧丘脑和左上纵束(SLF)II。FA的显着变化反映了从婴儿到成年的PT出生个体的WM异常。
    FA的显著变化反映了从婴儿期到年轻成年期出生的PT个体的WM异常。CC的异常发展,双侧丘脑和左侧SLF可能在PT个体的神经发育中起重要作用。
    神经系统疾病在早产(PT)出生的个体中很普遍。在扩散张量成像(DTI)研究中使用基于束的空间统计(TBSS)已被证明可有效检测大脑白质(WM)的微结构异常。为了确定早产人群中WM最一致的改变,我们已经在该PT出生人群中使用TBSS筛选了DTI研究,直至2022年10月。荟萃分析确定了PT组中各向异性分数(FA)低于足月出生的四个大脑区域。定量荟萃分析确定了call体,双侧丘脑和左上纵束II。作为最健壮的WM改变。各种研究已经证明了PT出生之间的联系,智商,胎龄和受试者年龄。
    UNASSIGNED: Neurological disorders are common in preterm (PT) born individuals. Diffusion tensor imaging (DTI) studies using tract-based spatial statistics (TBSS) effectively detect microstructural white matter (WM) abnormalities in the brain. We conducted this systematic review to integrate the findings of TBSS studies to determine the most consistent WM alterations in PT born individuals.
    UNASSIGNED: PubMed, Embase, Web of Science and Science Direct were searched. DTI studies using TBSS in PT born individuals were screened up to October 2022. The systematic review included studies reporting alterations in FA values for the entire brain in a stereotactic space, with three coordinates (x, y, z), according to the seed-based d mapping method.
    UNASSIGNED: The search strategy identified seventeen studies that fulfilled our inclusion criteria, with a total of 911 PT-born individuals and 563 matched controls were analysed. Of the seventeen studies, eight were dedicated to 650 adults, five to 411 children and four to 413 infants. Ten studies recruited 812 individuals born very prematurely (GA <29 weeks), six studies recruited 386 moderately premature individuals (GA = 29-32 weeks) and one study recruited 276 individuals born late prematurely (GA >32 weeks). This meta-analysis of six studies including 388 individuals highlighted four brain regions in which fractional anisotropy (FA) was lower in PT group than in people born at term. The quantitative meta-analysis found that the most robust WM alterations were located in the corpus callosum (CC), the bilateral thalamus and the left superior longitudinal fasciculus (SLF) II. Significant changes in FA reflect WM abnormalities in PT born individuals from infant to young adulthood.
    UNASSIGNED: Significant changes in FA reflect WM abnormalities in individuals born PT from infancy to young adulthood. The abnormal development of the CC, bilateral thalamus and left SLF may play a vital role in the neurodevelopment of PT individuals.
    Neurological disorders are prevalent in preterm (PT) born individuals. The use of tract-based spatial statistics (TBSS) in diffusion tensor imaging (DTI) studies has proven effective in detecting microstructural abnormalities of the white matter (WM) of the brain. In order to determine the most consistent alterations in WM among those born prematurely, we have screened DTI studies using TBSS in this PT born population up until October 2022. The meta-analysis identified four brain regions where fractional anisotropy (FA) was lower in the PT group than in those born at term. The quantitative meta-analysis identified the corpus callosum, the bilateral thalamus and the left superior longitudinal fasciculus II. As the most robust WM alterations. Various studies have demonstrated the links between PT birth, intelligence quotient, gestational age and subject age.
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  • 文章类型: Journal Article
    单晶氟化钡(BaF2),以其在红外光谱中的特殊光学特性而闻名,在超精密加工过程中表现出影响表面质量和材料去除效率的各向异性。本研究通过将纳米划痕测试与分子动力学(MD)模拟相结合,探索了各向异性对单晶BaF2的变形和去除机制的影响。使用斜坡加载模式在各种取向的单晶BaF2表面上进行的纳米划痕测试有助于识别表面裂纹和系统地描述材料去除行为。这项研究阐明了晶体取向对单晶BaF2的韧性-脆性转变(DBT)的影响,进一步开发了DBT在(111)晶面上的临界深度预测模型,以揭示潜在的各向异性机制。此外,单晶BaF2的纳米摩擦和磨损行为主要受划痕方向的影响,晶体表面,和施加的载荷,(110)和(100)平面显示出明显的摩擦和磨损各向异性。摩擦系数模型,考虑材料的弹性恢复,建立各向异性摩擦与磨损行为之间的内在关系,尺寸效应,和划痕方向。最后,纳米光栅单晶BaF2的MD模型揭示了沿(111)[-110]和[-1-12]晶体方向的位错和应变分布的多样性,为BaF2各向异性的起源提供原子尺度的见解。因此,本研究为具有各向异性的氟基红外光学材料的高效加工提供了理论基础。
    Monocrystalline barium fluoride (BaF2), known for its exceptional optical properties in the infrared spectrum, exhibits anisotropy that influences surface quality and material removal efficiency during ultraprecision machining. This research explores the impact of anisotropy on the deformation and removal mechanisms of monocrystalline BaF2 by integrating nanoscratch tests with molecular dynamics (MD) simulations. Nanoscratch tests conducted on variously oriented monocrystalline BaF2 surfaces using a ramp loading mode facilitated the identification of surface cracks and a systematic description of material removal behaviors. This study elucidates the effect of crystal orientation on the ductile-brittle transition (DBT) of monocrystalline BaF2, further developing a critical depth prediction model for DBT on the (111) crystal plane to reveal the underlying anisotropy mechanisms. Moreover, nanofriction and wear behaviors in monocrystalline BaF2 are found to be predominantly influenced by scratch direction, crystal surface, and applied load, with the (110) and (100) planes showing pronounced frictional and wear anisotropy. A coefficient of friction model, accounting for the material\'s elastic recovery, establishes the intrinsic relationship between anisotropic friction and wear behaviors, the size effect, and scratch direction. Lastly, MD modeling of nanoscratched monocrystalline BaF2 reveals the diversity of dislocations and strain distributions along the (111) [-110] and [-1-12] crystal directions, offering atomic scale insights into the origins of BaF2 anisotropy. Thus, this study provides a theoretical foundation for the efficient processing of fluorine-based infrared optic materials exhibiting anisotropy.
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  • 文章类型: Journal Article
    仿生人造皮肤,模仿人体皮肤的特征和功能,在可穿戴人机界面中具有广泛的应用。然而,为人造材料配备类似皮肤的机械性能,自我修复能力,高灵敏度仍然具有挑战性。这里,受人类皮肤结构的启发,制备了一种基于离子凝胶复合材料的人造皮肤,该人造皮肤具有定制的机械性能和坚固的界面。结合有限元分析和直接墨水书写(DIW)3D打印技术,具有刚性骨架和离子凝胶基质的离子凝胶复合材料经过精确设计和制造,实现精确模仿人体皮肤的力学各向异性和非线性力学响应。坚固的界面是通过共同固化的骨架和基体树脂,显著提高了复合材料的稳定性。自修复能力和抗裂纹扩展的实现进一步确保了用于感测应用的人造皮肤的显著耐久性。总之,仿生人造皮肤模仿人类皮肤的特征,包括机械各向异性,非线性力学响应,自我修复能力,耐久性和高灵敏度时,应用作为柔性传感器。这些策略为具有自适应力学行为的组织样材料的制造提供了强有力的支持。
    Bionic artificial skin which imitates the features and functions of human skin, has broad applications in wearable human-machine interfaces. However, equipping artificial materials with skin-like mechanical properties, self-healing ability, and high sensitivity remains challenging. Here, inspired by the structure of human skin, an artificial skin based on ionogel composites with tailored mechanical properties and robust interface is prepared. Combining finite element analysis and direct ink writing (DIW) 3D printing technology, an ionogel composite with a rigid skeleton and an ionogel matrix is precisely designed and fabricated, realizing the mechanical anisotropy and nonlinear mechanical response that accurately mimic human skin. Robust interface is created through co-curing of the skeleton and matrix resins, significantly enhancing the stability of the composite. The realization of self-healing ability and resistance to crack growth further ensure the remarkable durability of the artificial skin for sensing application. In summary, the bionic artificial skin mimics the characteristics of human skin, including mechanical anisotropy, nonlinear mechanical response, self-healing capability, durability and high sensitivity when applied as flexible sensors. These strategies provide strong support for the fabrication of tissue-like materials with adaptive mechanical behaviors.
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  • 文章类型: Clinical Study
    背景:注意缺陷/多动障碍(ADHD)是一种神经发育疾病,通常持续到成年期。已经确定了大脑连通性的潜在改变,但也有一些相关的联系,比如中间,上级,和下小脑柄(MCP,SCP,ICP,分别),大部分仍未开发;因此,我们试图调查小脑柄是否与成人ADHD的病理生理学有关.
    方法:我们应用扩散加权球形反卷积纤维束成像技术解剖了患有ADHD的成年男性(包括对哌醋甲酯有反应或没有反应的男性,基于2个月时至少30%的症状改善)和对照。我们使用敏感性分析调查了对照和整个ADHD样本之间以及对照和治疗反应组之间的道指标差异。最后,我们分析了道指标与临床神经心理状况之间的关联.
    结果:我们包括60名患有ADHD的参与者(包括42名治疗应答者和18名无应答者)和20名对照参与者。在整个多动症样本中,MCP分数各向异性(FA;t78=3.24,p=0.002)和位阻调制取向各向异性(HMOA;t78=3.01,p=0.004)降低,右ICP的径向扩散率(RD)增加(t78=-2.84,p=0.006),与对照组相比。尽管MCPFA和HMOA的病例对照差异,反映白质微结构组织,由两个治疗反应组驱动,在正确的ICPRD中,只有响应者与对照组显着不同,与髓鞘形成有关(t60=3.14,p=0.003)。阻碍调节MCP的取向各向异性与多动措施显着相关。
    结论:本研究仅包括患有ADHD的成年男性。进一步的研究需要调查潜在的性别和发展相关的差异。
    结论:这些结果支持小脑网络的作用,尤其是MCP,在成人ADHD的病理生理学方面,应鼓励进一步研究。
    背景:NCT03709940。
    BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition that often persists into adulthood. Underlying alterations in brain connectivity have been identified but some relevant connections, such as the middle, superior, and inferior cerebellar peduncles (MCP, SCP, and ICP, respectively), have remained largely unexplored; thus, we sought to investigate whether the cerebellar peduncles contribute to ADHD pathophysiology among adults.
    METHODS: We applied diffusion-weighted spherical deconvolution tractography to dissect the cerebellar peduncles of male adults with ADHD (including those who did or did not respond to methylphenidate, based on at least 30% symptom improvement at 2 months) and controls. We investigated differences in tract metrics between controls and the whole ADHD sample and between controls and treatment-response groups using sensitivity analyses. Finally, we analyzed the association between the tract metrics and cliniconeuropsychological profiles.
    RESULTS: We included 60 participants with ADHD (including 42 treatment responders and 18 nonresponders) and 20 control participants. In the whole ADHD sample, MCP fractional anisotropy (FA; t 78 = 3.24, p = 0.002) and hindrance modulated orientational anisotropy (HMOA; t 78 = 3.01, p = 0.004) were reduced, and radial diffusivity (RD) in the right ICP was increased (t 78 = -2.84, p = 0.006), compared with controls. Although case-control differences in MCP FA and HMOA, which reflect white-matter microstructural organization, were driven by both treatment response groups, only responders significantly differed from controls in right ICP RD, which relates to myelination (t 60 = 3.14, p = 0.003). Hindrance modulated orientational anisotropy of the MCP was significantly positively associated with hyperactivity measures.
    CONCLUSIONS: This study included only male adults with ADHD. Further research needs to investigate potential sex- and development-related differences.
    CONCLUSIONS: These results support the role of the cerebellar networks, especially of the MCP, in adult ADHD pathophysiology and should encourage further investigation.
    BACKGROUND: NCT03709940.
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  • 文章类型: Journal Article
    由于低信噪比(SNR)和由磁场梯度中的图像伪影和缺陷导致的系统误差,扩散张量成像(DTI)度量和纤维束成像可能被偏置。缺陷包括非均匀性和非线性,涡流引起的影响,以及背景和成像梯度的影响。我们研究了系统误差对各向同性体模的DTI指标和高分辨率测量的DTI指标以及大鼠大脑的纤维束成像的影响。我们测试了去噪和吉布斯振铃去除方法与B矩阵空间分布(BSD)方法相结合的磁场梯度校准。结果表明,BSD方法的性能取决于吉布斯振铃是否被消除以及随机误差消除的有效性。基于感兴趣区域(ROI)的DTI指标分析表明,取决于ROI的大小及其在空间中的位置,校正方法可以在不同程度上消除系统偏差。提出并致力于这种类型的数据的预处理管道与BSD方法一起导致各向同性体模中的分数各向异性(FA)(全局和局部)降低了90%,在大鼠大脑中降低了45%。去噪后,与未进行预处理(sDTI)的标准方法相比,大鼠脑示踪图的总体变化最大。去噪后从DTI获得的第一个特征向量的方向,在去噪和吉布斯振铃去除后,ROI与sDTI和sDTI的Gibbs振铃去除和BSD平均相差56和10度,分别。由于消除了与不完美的磁场梯度有关的系统误差,因此可以通过纤维束造影的改进来识别后者。根据结果,高分辨率数据的系统偏差主要取决于信噪比,但是也可以看到非均匀梯度的影响。去噪之后,BSD方法能够进一步校正大鼠大脑中扩散张量的度量和纤维束成像,方法是考虑到磁场梯度的实际分布与被检查对象无关,并且唯一依赖于扫描仪和序列。这意味着体内研究也受到这种类型的错误,在处理此类数据时应考虑到这一点。
    Diffusion tensor imaging (DTI) metrics and tractography can be biased due to low signal-to-noise ratio (SNR) and systematic errors resulting from image artifacts and imperfections in magnetic field gradients. The imperfections include non-uniformity and nonlinearity, effects caused by eddy currents, and the influence of background and imaging gradients. We investigated the impact of systematic errors on DTI metrics of an isotropic phantom and DTI metrics and tractography of a rat brain measured at high resolution. We tested denoising and Gibbs ringing removal methods combined with the B matrix spatial distribution (BSD) method for magnetic field gradient calibration. The results showed that the performance of the BSD method depends on whether Gibbs ringing is removed and the effectiveness of stochastic error removal. Region of interest (ROI)-based analysis of the DTI metrics showed that, depending on the size of the ROI and its location in space, correction methods can remove systematic bias to varying degrees. The preprocessing pipeline proposed and dedicated to this type of data together with the BSD method resulted in an even - 90% decrease in fractional anisotropy (FA) (globally and locally) in the isotropic phantom and - 45% in the rat brain. The largest global changes in the rat brain tractogram compared to the standard method without preprocessing (sDTI) were noticed after denoising. The direction of the first eigenvector obtained from DTI after denoising, Gibbs ringing removal and BSD differed by an average of 56 and 10 degrees in the ROI from sDTI and from sDTI after denoising and Gibbs ringing removal, respectively. The latter can be identified with the amount of improvement in tractography due to the elimination of systematic errors related to imperfect magnetic field gradients. Based on the results, the systematic bias for high resolution data mainly depended on SNR, but the influence of non-uniform gradients could also be seen. After denoising, the BSD method was able to further correct both the metrics and tractography of the diffusion tensor in the rat brain by taking into account the actual distribution of magnetic field gradients independent of the examined object and uniquely dependent on the scanner and sequence. This means that in vivo studies are also subject to this type of errors, which should be taken into account when processing such data.
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  • 文章类型: Journal Article
    超分子材料已经使用广泛的相互作用进行组装,包括疏水效应,DNA碱基配对,和氢键。具体来说,具有疏水性结构单元的DNA两亲物根据两个嵌段的长度和组成自组装成不同的形态。在这里,我们利用不同超分子相互作用的正交性-疏水效应,Watson-Crick-Franklin碱基配对和RNA接吻环-在纳米和微米尺度上创建具有受控形态的分层自组装体。通过碱基配对组装导致杂种的形成,具有高刚度和自修复性能的多相水凝胶。通过疏水核心相互作用的组装给出各向异性,离散组件,其中具有一个序列的DNA纤维终止于具有不同序列的DNA球体。这项工作为自下而上构建基于DNA的材料开辟了新的途径,在药物输送中具有广阔的应用前景,组织工程,以及从最少的组件阵列中创建复杂的DNA结构。
    Supramolecular materials have been assembled using a wide range of interactions, including the hydrophobic effect, DNA base-pairing, and hydrogen bonding. Specifically, DNA amphiphiles with a hydrophobic building block self-assemble into diverse morphologies depending on the length and composition of both blocks. Herein, we take advantage of the orthogonality of different supramolecular interactions - the hydrophobic effect, Watson-Crick-Franklin base pairing and RNA kissing loops - to create hierarchical self-assemblies with controlled morphologies on both the nanometer and the micrometer scales. Assembly through base-pairing leads to the formation of hybrid, multi-phasic hydrogels with high stiffness and self-healing properties. Assembly via hydrophobic core interactions gives anisotropic, discrete assemblies, where DNA fibers with one sequence are terminated with DNA spheres bearing different sequences. This work opens new avenues for the bottom-up construction of DNA-based materials, with promising applications in drug delivery, tissue engineering, and the creation of complex DNA structures from a minimum array of components.
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  • 文章类型: Journal Article
    近年来,基于植物的肉类类似物越来越引起食品工业的关注。然而,人们对这种创新的固体食物在人体胃中的消化行为知之甚少。在这项研究中,在使用/不使用高水分挤压技术和在不同温度下制备具有不同内部结构的基于植物的肉类似物。应用了半动态胃消化系统,该系统涉及胃液分泌和胃排空的模拟过程。高温(150℃)挤压处理后,EHT具有最高的各向异性指数(HHL/H44%=1.90)和理想的肉样结构。发现在胃消化的早期阶段,EHT的推注中同时发生颗粒崩解和溶胀,但在未经挤压处理(HLT)的样品中却没有。这种差异可能归因于挤压产生的EHT的紧凑和排列良好的各向异性结构。并导致难以酶促水解,除非颗粒溶胀和展开聚合物链。胃消化过程中EHT中颗粒崩解的困难是胃排空速率相对较慢和蛋白质降解减少的结果。因此,在高温下进行挤压处理并具有最佳各向异性纤维结构的EHT表现出最慢的胃消化。这种新型固体食物显示出良好的潜力,可作为饮食人群所需的营养食品。
    Plant-based meat analogs have increasingly attracted the attention of the food industry in recent years. However, the digestion behavior of this innovative solid food in human stomach is poorly understood. In this study, plant-based meat analogs with different internal structures were prepared with/without high-moisture extrusion technology and at different temperatures. A semi-dynamic gastric digestion system which involves the mimic processes of the secretion of gastric juice and the gastric emptying was applied. After extrusion treatment at high temperature (150 ℃), the EHT had the highest anisotropic index (H⊥/H∥=1.90) and an ideal meat-like structure. It was found that particle disintegration and swelling simultaneously occurred in the bolus of the EHT but not in the sample without extrusion treatment (the HLT) in the early stage of gastric digestion. This difference might be attributed to the compact and well-arranged anisotropic structure of the EHT resulting from the extrusion, and leads to difficult enzymatic hydrolyzation unless the particles swell and unfold the polymer chains. The difficulty in particle disintegration in the EHT during gastric digestion is the consequence of the relatively slow gastric emptying rate and the decrease of protein degradation. As a result, the EHT which underwent extrusion treatment at high temperature and possessed the best anisotropic fibrous structure exhibited the slowest gastric digestion. This novel solid food shows good potential as a desired nutritional food for people on diet.
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