Flexibility

灵活性
  • 文章类型: Journal Article
    S-奥美拉唑和R-雷贝拉唑是用于治疗消化性疾病的重要质子泵抑制剂(PPI)。它们可以由Baeyer-Villiger单加氧酶(BVMO)催化的相应硫化物生物合成。在用于目标亚砜制备的BVMOs的开发过程中,立体选择性和过氧化程度是最重要的考虑因素。在本研究中,先前设计的LnPAMO-Mu15和嗜热菌的TtPAMO分别对硫醚具有较高的(S)和(R)构型立体选择性。发现TtPAMO能够分别将奥美拉唑硫化物(OPS)和雷贝拉唑硫化物(RPS)氧化为R-奥美拉唑和R-雷贝拉唑。然而,TtPAMO存在的过氧化问题限制了TtPAMO在亚砜生物合成中的应用。揭示了LnPAMO-Mu15和TtPAMO对OPS的不利立体选择性以及TtPAMO对OPS的过度氧化的结构机制,基于此,TtPAMO的合理设计侧重于催化位点附近回路的灵活性。筛选出变体TtPAMO-S482Y,其对OPS和RPS的过氧化程度最低,这是由于催化中心的柔性比TtPAMO降低。这项研究的成功不仅证明了本研究中提出的过氧化机理的合理性,而且为BVMOs向硫醚底物的发展提供了线索,用于相应的亚砜制备。
    S-omeprazole and R-rabeprazole are important proton pump inhibitors (PPIs) used for treating peptic disorders. They can be biosynthesized from the corresponding sulfide catalyzed by Baeyer-Villiger monooxygenases (BVMOs). During the development of BVMOs for target sulfoxide preparation, stereoselectivity and overoxidation degree are important factors considered most. In the present study, LnPAMO-Mu15 designed previously and TtPAMO from Thermothelomyces thermophilus showed high (S)- and (R)-configuration stereoselectivity respectively towards thioethers. TtPAMO was found to be capable of oxidating omeprazole sulfide (OPS) and rabeprazole sulfide (RPS) into R-omeprazole and R-rabeprazole respectively. However, the overoxidation issue existed and limited the application of TtPAMO in the biosynthesis of sulfoxides. The structural mechanisms for adverse stereoselectivity between LnPAMO-Mu15 and TtPAMO towards OPS and the overoxidation of OPS by TtPAMO were revealed, based on which, TtPAMO was rationally designed focused on the flexibility of loops near catalytic sites. The variant TtPAMO-S482Y was screened out with lowest overoxidation degree towards OPS and RPS due to the decreased flexibility of catalytic center than TtPAMO. The success in this study not only proved the rationality of the overoxidation mechanism proposed in this study but also provided hints for the development of BVMOs towards thioether substrate for corresponding sulfoxide preparation.
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  • 文章类型: Journal Article
    本研究成功制备了一种新型SA/BF/Gel复合导电水凝胶,具有粘合和自修复性能。通过深入研究,凝胶含量对拉伸的影响,粘合剂,自我修复特性,讨论了SA/BF/Gel复合导电水凝胶的导电性。还研究了材料的传感性能和传感机理,并对其潜在应用进行了初步探索。尝试将SA/BF/Gel复合导电水凝胶应用于3D打印技术,在水凝胶的流变特性与其打印结构之间建立联系。凝胶的加入显著提高了水凝胶的柔韧性,在1.5%的凝胶含量下,电导率高达3.12S/m。当用作传感器时,该材料表现出高灵敏度(GF=2.21)和优异的循环稳定性,渲染它适用于手指和手腕的弯曲运动的实时监测的广泛应用,以及水凝胶表面上的动态接触和接触力的变化。SA/BF/Gel复合导电水凝胶具有用于多种应用的潜力,包括智能可穿戴设备的开发,对个体的监控,以及人类和机器的融合。此外,与这种水凝胶相关的研究结果将为材料科学的发展和智能技术的整合提供坚实的基础。
    This study has been successfully developed the Sodium alginate/Bamboo fiber /Gelatin(SA/BF/Gel)composite conductive hydrogel with adhesive and self-healing properties. Through in-depth research, the influence of Gel content on the tensile, adhesive, self-healing properties, and conductivity of the SA/BF/Gel composite conductive hydrogel was discussed. The sensing performance and sensing mechanism of the material were also investigated, along with a preliminary exploration of its potential applications. An attempt was made to apply the SA/BF/Gel composite conductive hydrogel to 3D printing technology, establishing a connection between the rheological properties of the hydrogel and its printing structure. The addition of Gel significantly improved the flexibility of the hydrogel, with a conductivity of up to 3.12 S/m at a Gel content of 1.5 %. When employed as a sensor, the material exhibited high sensitivity (GF = 2.21) and excellent cyclic stability, rendering it suitable for a wide range of applications in real-time monitoring of bending movements of fingers and wrists, as well as dynamic contact and variations in contact forces on the hydrogel surface. The SA/BF/Gel composite conductive hydrogel has the potential to be utilized in a multitude of applications, including the development of smart wearable devices, the monitoring of individual human beings, and the integration of human beings and machines. Furthermore, the research findings associated with this hydrogel will provide a strong foundation for the advancement of materials science and the integration of smart technologies.
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  • 文章类型: Journal Article
    抗结冰/除冰涂层具有低能耗和优异的柔韧性,可以更好地满足实际工程中的应用要求。在本文中,制备了基于碳纳米材料的主动-被动集成防冰/除冰涂层,它不仅具有电热转换的各种功能,光热转换,和超疏水性,但也显示出适应弯曲表面的大变形能力。涂层由夹层结构的底部和顶层组成,前者包括由密集混合的碳纳米管(CNT)和石墨烯制成的芯导电层和两个聚二甲基硅氧烷(PDMS)包裹层,而后者是填充有TiN和SiO2纳米颗粒的聚合物复合材料。实验研究表明,当本涂层仅在电场下工作时,可以实现90%的电能转化为热能,只有2V的电压足以在400s内以负20度解冻表面,和2.5V的稍大的电压导致在200s内超过100°C的显着温度升高。这些所需的电压明显小于现有的基于电热的方法中的对应电压,以实现相同的加热效果,这可以进一步减少与阳光照明的辅助作用。因此,可以用小的能量输入实现快速和完全的除冰/除霜。此外,防水功能,电属性,涂层的电热转换性能在经过较大的弯曲变形或多次弯曲循环后几乎保持不变,从而确保在平面和曲面上的出色防冰/除冰效果。所有结果都证明了本发明涂层的明显优点,包括高效率,低能耗,全天候适应性,和出色的灵活性,这对于不同形状的工业设备的防冻保护具有重要的实用价值。
    Anti-icing/deicing coatings with low energy consumption and superior flexibility could better fit application requirements in practical engineering. In this paper, an active-passive-integrated anti-icing/deicing coating based on carbon nanomaterials is prepared, which not only possesses various functions of electrothermal conversion, photothermal conversion, and superhydrophobicity but also shows a large deformability to accommodate curved surfaces. The coating consists of a sandwich-structured bottom part and top layer, the former of which includes a core conductive layer made of densely mixed carbon nanotubes (CNTs) and graphene and two polydimethylsiloxane (PDMS) wrapping layers, while the latter is a polymeric composite filled with TiN and SiO2 nanoparticles. Experimental studies show that, when the present coating works under an electric field alone, a 90% conversion of electric energy to thermal energy can be realized, only a 2 V voltage is enough to unfreeze the surface at minus 20 degrees within 400 s, and a slightly larger voltage of 2.5 V leads to a significant temperature increase of more than 100 °C within 200 s. Such required voltages are significantly smaller than their counterparts in existing electrothermal-based methods to achieve the same heating effects, which could be further diminished with the auxiliary action of sunlight illumination. A fast and complete deicing/defrosting can be consequently achieved with a small energy input. Furthermore, the water repellency function, electric property, and electrothermal conversion performance of the coating remain almost unchanged after either a large bending deformation or many bending cycles, thus ensuring an outstanding anti-icing/deicing effect on both flat and curved surfaces. All of the results demonstrate apparent advantages of the present coating including high efficiency, low energy consumption, all-weather adaptability, and excellent flexibility, which should be of great practical value for the freeze protection of differently shaped industrial equipment.
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  • 文章类型: Journal Article
    前药纳米组装体结合了前药策略和纳米技术的优点,已被广泛用于递送抗肿瘤药物。这些前药通常包含活性药物模块,响应模块,和修改模块。其中,修饰模块是提高母体药物自组装能力的关键因素。然而,修饰模块的特定结构对前药自组装的影响仍然难以捉摸。在这项研究中,使用2-辛基-1-十二烷醇(OD)作为柔性修饰模块和胆固醇(CLS)作为刚性修饰模块开发了两种吉西他滨(GEM)前药。有趣的是,改性模块化学结构的差异显著影响组装性能,药物释放,细胞毒性,肿瘤积聚,前药纳米组装体的抗肿瘤功效。值得注意的是,用柔性修饰链(OD)构建的前药纳米组装体显示出改善的稳定性,更快的药物释放,和增强的抗肿瘤作用。我们的发现阐明了修饰模块对前药纳米组装体构建的重要影响。
    Prodrug nanoassemblies combine the advantages of prodrug strategies and nanotechnology have been widely utilized for delivering antitumor drugs. These prodrugs typically comprise active drug modules, response modules, and modification modules. Among them, the modification modules play a critical factor in improving the self-assembly ability of the parent drug. However, the impact of the specific structure of the modification modules on prodrug self-assembly remains elusive. In this study, two gemcitabine (GEM) prodrugs are developed using 2-octyl-1-dodecanol (OD) as flexible modification modules and cholesterol (CLS) as rigid modification modules. Interestingly, the differences in the chemical structure of modification modules significantly affect the assembly performance, drug release, cytotoxicity, tumor accumulation, and antitumor efficacy of prodrug nanoassemblies. It is noteworthy that the prodrug nanoassemblies constructed with flexible modifying chains (OD) exhibit improved stability, faster drug release, and enhanced antitumor effects. Our findings elucidate the significant impact of modification modules on the construction of prodrug nanoassemblies.
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  • 文章类型: Journal Article
    石墨,资源丰富,成本低,被认为是钾离子电池(PIBs)的有前途的负极材料。然而,因为钾离子的体积很大,石墨夹层之间钾的嵌入/脱嵌导致其巨大的体积膨胀,导致循环稳定性和倍率性能差。在这里,采用自传播还原策略来制造柔性,自支撑3D多孔石墨@还原氧化石墨烯(3D-G@rGO)复合膜用于PIBs。3D多孔网络不仅可以有效地减轻石墨中的体积膨胀,而且可以为钾储存提供许多活性位点,并允许电解质渗透和快速离子迁移。因此,与原始石墨阳极相比,柔性3D-G@rGO薄膜电极表现出大大提高的K存储性能,在0.1C时的可逆容量为452.8mAhg-1,100次循环后的容量保持率为80.4%。它还具有出色的倍率性能,在2和5C下保持139.1和94.2mAhg-1的高比容量,分别。提出的自蔓延还原策略构建三维自支撑结构是提高石墨阳极结构稳定性和储钾性能的可行途径。
    Graphite, with abundant resources and low cost, is regarded as a promising anode material for potassium-ion batteries (PIBs). However, because of the large size of potassium ions, the intercalation/deintercalation of potassium between the interlayers of graphite results in its huge volume expansion, leading to poor cycling stability and rate performance. Herein, a self-propagating reduction strategy is adopted to fabricate a flexible, self-supporting 3D porous graphite@reduced graphene oxide (3D-G@rGO) composite film for PIBs. The 3D porous network can not only effectively mitigate the volume expansion in graphite but also provide numerous active sites for potassium storage as well as allow for electrolyte penetration and rapid ion migration. Therefore, compared to the pristine graphite anode, the flexible 3D-G@rGO film electrode exhibits greatly improved K-storage performance with a reversible capacity of 452.8 mAh g-1 at 0.1 C and a capacity retention rate of 80.4% after 100 cycles. It also presents excellent rate capability with a high specific capacity of 139.1 and 94.2 mAh g-1 maintained at 2 and 5 C, respectively. The proposed self-propagating reduction strategy to construct a three-dimensional self-supporting structure is a viable route to improve the structural stability and potassium storage performance of graphite anodes.
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  • 文章类型: Journal Article
    本研究首先从植物细胞壁和蜂窝状结构的双重仿生设计中汲取灵感,利用其结构特点,设计出能够实现显著变形和承受较大载荷的柔性壳体结构。基于这种柔性壳体结构的交错粘结,提出了一种新的大载荷气动软臂设计方案,并建立了其柔性和承载能力的数学模型。这种新型软臂的延伸和弯曲变形来自柔性壳体结构的几何可变性,可以通过两个开关控制,即,通货紧缩和通货膨胀,实现延伸或弯曲动作。实验结果表明,在150kpa范围内的驱动压力下,软手臂的最大伸长达到23.17厘米,最大弯曲角度为94.2度,和最大负载为2.83N。这种类型的软臂基于双仿生灵感设计可以同时具有高负载能力和灵活性。研究成果为高负荷软臂的研制提供了新的思路和方法,预计将从实验室扩展到多个领域。
    This study first draws inspiration from the dual biomimetic design of plant cell walls and honeycomb structures, drawing on their structural characteristics to design a flexible shell structure that can achieve significant deformation and withstand large loads. Based on the staggered bonding of this flexible shell structure, we propose a new design scheme for a large-load pneumatic soft arm and establish a mathematical model for its flexibility and load capacity. The extension and bending deformation of this new type of soft arm come from the geometric variability of flexible shell structures, which can be controlled through two switches, namely, deflation and inflation, to achieve extension or bending actions. The experimental results show that under a driving pressure within the range of 150 kpa, the maximum elongation of the soft arm reaches 23.17 cm, the maximum bending angle is 94.2 degrees, and the maximum load is 2.83 N. This type of soft arm designed based on dual bionic inspiration can have both a high load capacity and flexibility. The research results provide new ideas and methods for the development of high-load soft arms, which are expected to expand from laboratories to multiple fields.
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  • 文章类型: Journal Article
    柔性压阻式传感器在可穿戴设备、电子皮肤,和人机界面由于其有利的特点,包括低功耗,优异的弯曲稳定性,广泛的测试压力范围,和简单的制造技术。随着智能技术的进步,对灵敏度的要求更高,准确度,响应时间,测量范围,和耐候性的压阻式传感器正在兴起。由于聚合物多孔材料和导电相的可设计性,有了更多的多元组合,可以实现更高的灵敏度和更低的检测限,比传统的柔性传感器材料更有前途。基于此,这项工作回顾了利用聚合物多孔材料的柔性压力传感器研究的最新进展。此外,这篇综述从三维多孔柔性基底调节的角度研究了传感器性能的优化和发展,传感材料选择和复合技术,衬底和传感材料结构设计。
    Flexible piezoresistive sensors are in high demand in areas such as wearable devices, electronic skin, and human-machine interfaces due to their advantageous features, including low power consumption, excellent bending stability, broad testing pressure range, and simple manufacturing technology. With the advancement of intelligent technology, higher requirements for the sensitivity, accuracy, response time, measurement range, and weather resistance of piezoresistive sensors are emerging. Due to the designability of polymer porous materials and conductive phases, and with more multivariate combinations, it is possible to achieve higher sensitivity and lower detection limits, which are more promising than traditional flexible sensor materials. Based on this, this work reviews recent advancements in research on flexible pressure sensors utilizing polymer porous materials. Furthermore, this review examines sensor performance optimization and development from the perspectives of three-dimensional porous flexible substrate regulation, sensing material selection and composite technology, and substrate and sensing material structure design.
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  • 文章类型: Journal Article
    跌倒是老年人意外死亡的主要原因,绝经后妇女因骨质疏松症而面临更大的跌倒风险。本研究旨在研究太极拳练习对处于危险中的女性平衡控制和功能适应性的影响。
    中国女性自我报告有跌倒倾向,并且基线单腿站立测试时间(太极拳组4.1秒)低于其年龄组的全国平均水平(60-64岁:10.9秒,65-69岁:9.9s)被分配到对照组(n=26,平均年龄=63.9岁)或太极拳组(n=24,平均年龄=63.9岁)。太极拳组参加了为期12周的监督干预,对照组保持日常活动。每次锻炼的平均持续时间为52分钟。在干预开始和结束时评估静态平衡和功能适应性。
    12周后,太极拳组的平衡性明显优于对照组,灵活性,和肌肉健康(所有p<0.05)。太极拳组的参与者的单腿站立改善了61.0%(2.5s,套期保值的g=0.85),手臂卷曲8.3%(+1.7次重复,g=0.53),握力下降8.3%(+1.9公斤,g=0.65),坐姿达163.2%(+6.2厘米,g=1.17)。
    平衡的改善,再加上其他功能性健身益处,这表明太极拳对于跌倒风险较高的老年女性来说是一种有用的运动。
    UNASSIGNED: Falls are the leading cause of accidental death among older persons, with postmenopausal women facing a greater hazard of falling due to osteoporosis. This study aimed to examine the effects of Taijiquan practice on balance control and functional fitness in at-risk females.
    UNASSIGNED: Chinese women who self-reported a tendency to fall and had a baseline one-leg stand test time (4.1 s in the Taijiquan group) below the national average for their age group (60-64 years: 10.9 s, 65-69 years: 9.9 s) were assigned to either a control group (n = 26, mean age = 63.9 years) or a Taijiquan group (n = 24, mean age = 63.9 years). The Taijiquan group participated in a 12-week supervised intervention, while the control group maintained their daily activities. The average duration of each exercise session was 52 min. Static balance and functional fitness were assessed at the beginning and end of the intervention.
    UNASSIGNED: After 12 weeks, the Taijiquan group significantly outperformed the control group in terms of balance, flexibility, and muscular fitness (all p < 0.05). Participants in the Taijiquan group improved their one-leg stand by 61.0% (+2.5 s, Hedge\'s g = 0.85), arm curl by 8.3% (+1.7 repetitions, g = 0.53), handgrip strength by 8.3% (+1.9 kg, g = 0.65), and sit-and-reach by 163.2% (+6.2 cm, g = 1.17).
    UNASSIGNED: The improvement in balance, coupled with other functional fitness benefits, suggests that Taijiquan could serve as a useful exercise for older women with an elevated risk of falling.
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  • 文章类型: Journal Article
    纳米材料的灵活性具有挑战性,但值得针对生物医学应用进行调整。生物相容性二氧化硅纳米材料正在进行广泛的探索,但尽管具有聚合物性质,但很少观察到表现出柔韧性。在这里,据报道,超薄柔性二氧化硅纳米片(NS)是一种简单的一步法路线,其低厚度和高直径厚度比使折叠。可以容易地调节厚度和直径以实现受控的柔性。机理研究表明,除了常用的表面活性剂,带有两个疏水尾巴的“不常见”在生产片状/层状/带壳结构中起指导作用,而乙醇的添加适当地减轻了组装的表面活性剂的强界面张力,否则会产生大卷曲的片状结构。有了这些超薄NS,进一步表明,细胞对颗粒形状和刚性的偏好高度依赖于纳米颗粒的表面化学:在高颗粒细胞亲和力下,NS,尤其是柔性的将被哺乳动物细胞优选用于内化或附着,而当亲和力较低时,此首选项基本上是无效的。因此,超薄二氧化硅NSs的性能可以通过表面化学有效地扩展和增强,以实现改进的生物传感或药物递送。
    Flexibility of nanomaterials is challenging but worthy to tune for biomedical applications. Biocompatible silica nanomaterials are under extensive exploration but are rarely observed to exhibit flexibility despite the polymeric nature. Herein, a facile one-step route is reported to ultrathin flexible silica nanosheets (NSs), whose low thickness and high diameter-to-thickness ratio enables folding. Thickness and diameter can be readily tuned to enable controlled flexibility. Mechanism study reveals that beyond the commonly used surfactant, the \"uncommon\" one bearing two hydrophobic tails play a guiding role in producing sheeted/layered/shelled structures, while addition of ethanol appropriately relieved the strong interfacial tension of the assembled surfactants, which will otherwise produce large curled sheeted structures. With these ultrathin NSs, it is further shown that the cellular preference for particle shape and rigidity is highly dependent on surface chemistry of nanoparticles: under high particle-cell affinity, NSs, and especially the flexible ones will be preferred by mammalian cells for internalization or attachment, while this preference is basically invalid when the affinity is low. Therefore, properties of the ultrathin silica NSs can be effectively expanded and empowered by surface chemistry to realize improved bio-sensing or drug delivery.
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  • 文章类型: Journal Article
    低密度,高孔隙率,和出色的物理化学稳定性,陶瓷纳米线气凝胶和海绵表现出各种有趣的特性。在这里,超薄二氧化硅纳米线气凝胶(SiO2NWs-A)通过简单的化学气相沉积途径实现。除了良好的机械和热性能,揭示了活性水-气凝胶相互作用产生的特性,即,出色的透明度,强毛细管效应,增强的抗压强度(可逆应变为62%),当充满水时,可切换的润湿性和强大的形状保持能力。与这些有趣特性相关的物理机制基本上根据其独特的特征(明显减小的纳米线直径,富集的纳米级间隙通道,和加强网络)。为了显示优越性,一个有利的太阳能蒸汽发生系统(亲水NWs-A/还原氧化石墨烯(rGO)/疏水NWs-A)是通过整合这些有利的特性,与rGO疏水性NWs-A装置相比,产生显著提高的蒸气蒸发速率和能量效率。这些结果有助于纳米线气凝胶的结构设计和功能探索。
    With low density, high porosity, and outstanding physicochemical stability, ceramic nanowire aerogels and sponges exhibit various interesting properties. Herein, an ultrathin silica nanowire aerogel (SiO2 NWs-A) was achieved via a facile chemical vapor deposition route. In addition to good mechanical and thermal performances, properties resulting from active water-aerogel interactions are revealed, i.e., outstanding transparency, strong capillary effect, enhanced compressive strength (a reversible strain of ∼62%), switchable wettability and robust shape retention ability when filled with water. The physical mechanism related to these interesting properties is demonstrated basically according to its unique features (distinctly reduced nanowire diameter, enriched nanoscopic gap channels, and reinforced network). To demonstrate the superiority, an advantageous solar vapor generation system (hydrophilic NWs-A/reduced graphene oxide (rGO)/ hydrophobic NWs-A) was obtained by integrating these favorable characteristics, giving rise to remarkably promoted vapor evaporation rate and energy efficiency compared to the rGO hydrophobic NWs-A device. These results contribute to the structural design and functional exploration of nanowire aerogels.
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