mechanical

机械
  • 文章类型: Journal Article
    运动表现可能受到安慰剂和nocebo效应的影响。关于安慰剂和nocebo对运动和运动表现的影响的最后一篇文献综述于2019年发表。在过去的五年里,一些新的研究已经发表。这篇综述旨在更新以前的综合研究,并通过确定安慰剂或nocebo干预运动和运动的形式和程度来评估新研究的结果。因此,我们搜索了从2019年到2024年5月底在PubMed中索引的实证研究,Medline,WebofScience,EBSCO,和谷歌学者数据库。搜索产生了20个合格的对照或基线控制条件的研究,专注于营养,机械,和其他混合的致麦剂。他们对营养(d=0.86)产生了小到大的安慰剂效应(Cohen'sd),机械(d=0.38),奶油和凝胶(d=0.05),和开放标签安慰剂(d=0.16)干预措施。安慰剂效应的合并效应大小为中等至较大(d=0.67),比以前的审查要大,这表明安慰剂效应可以改善运动表现甚至比以前报道的更多。然而,根据三项研究的五项措施,nocebo效应几乎是其两倍(d=1.20)。因此,目前的研究结果支持并扩大了该领域的最新审查,为运动和锻炼中的安慰剂和nocebo效应提供了额外的支持。
    Sports performance could be affected by placebo and nocebo effects. The last literature review on placebo and nocebo effects on sports and exercise performance was published in 2019. In the past five years, several new studies have been published. This review aimed to update the previous synthesis and evaluate the results of new studies focusing on placebo or nocebo interventions in sports and exercise by determining the form and magnitude of their effect. Hence, we searched for empirical studies published from 2019 until the end of May 2024 indexed in PubMed, Medline, Web of Science, EBSCO, and Google Scholar databases. The search yielded 20 eligible studies with control or baseline-control conditions, focusing on nutritional, mechanical, and other mixed ergogenic aids. They yielded small to large placebo effects (Cohen\'s d) for nutritional (d = 0.86), mechanical (d = 0.38), cream and gel (d = 0.05), and open-label placebo (d = 0.16) interventions. The pooled effect size for placebo effects was moderate to large (d = 0.67), larger than in the earlier review, suggesting that placebo effects can improve motor performance even more than previously reported. However, based on five measures from three studies, the nocebo effects were almost twice as large (d = 1.20). Accordingly, the current findings support and expand the last review in the field by yielding additional support for placebo and nocebo effects in sports and exercise.
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  • 文章类型: Journal Article
    采用高强度材料,在高矿物质水分(最大重量为1098公斤)下连续使用后可保持其强度,用于航空航天,汽车,和电磁设备是具有挑战性的。一般来说,镍(Ni)及其合金涂层用于上述应用,但该系统的连续使用降低了其机械稳定性和结构完整性。对于汽车和航空航天用途,该材料应具有较高的机械强度,耐磨性,耐腐蚀性,和磁性。裸露的Ni涂层可以用增强的机械改变,通过在涂层中使用各种增强材料的摩擦学和电化学性能。大量使用的增强剂主要是碳质纳米同素异形体(如石墨烯,碳纳米管,和金刚石)用于制造复合涂层。当前的评论揭示了镍的引入以及对裸镍涂层的损坏的主要原因。此外,该评论阐明了如何减轻镍涂层的损害,重点是赋予独特的碳质纳米同素异形体的味道。对机械的共轭研究,磨损,腐蚀,综述包括电沉积Ni-碳质复合镀层的磁行为。因此,本评论可以得到读者的认可,以保护飞机,汽车,和电磁电器。
    The utilization of high-strength materials that can retain their strength after successive use under high mineral moisture (maximum weight of 1098 kg) for aerospace, automotive, and electromagnetic devices is challenging. Generally, coatings of nickel (Ni) and its alloys are utilized in the aforementioned applications, but the continuous use of the system degrades its mechanical stability and structural integrity. For the automotive and aerospace uses, the material should have high mechanical strength, wear tolerance, corrosion resistance, and magnetism. The bare Ni coatings can be altered with enhanced mechanical, tribological and electrochemical performances by using various reinforcements in the coatings. The abundantly used reinforcing agents are mainly carbonaceous nanoallotropes (such as graphene, carbon nanotubes, and diamond) for the fabrication of composite coatings. The current review unfolds the introduction of nickel and the major cause of damage to bare nickel coatings. Moreover, the review sheds light on how to mitigate the damage of nickel coatings with an emphasis on giving a flavor of distinct carbonaceous nanoallotropes. The conjugated studies on mechanical, wear, corrosion, and magnetic behavior of electrodeposited Ni-carbonaceous composite coatings are embraced in the review. Therefore, the present review can be endorsed by the readers for the protection of aircraft, automotive, and electromagnetic appliances.
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  • 文章类型: Journal Article
    天然纤维复合材料因其绿色环保、成本低而受到越来越多的关注。在天然纤维中,竹子的特点是生长快,培育期短,高强度和良好的韧性,是世界上最强的天然纤维之一。竹纤维增强聚合物复合材料(BFRPC)具有机械强度高的特点,低密度,降解性,等。它具有与金属材料相当的工业适用性,具有与玻璃和碳纤维等复合材料相同的强耐腐蚀性,与天然材料一样,对电磁干扰和低热导率的免疫力相同。其单向比强度和单向比模量高于玻璃纤维,仅次于碳纤维的极高价格,在复合材料领域发挥着越来越重要的作用,并可广泛应用于风力发电领域,建筑,航空,汽车,医疗等等。目前,它最初被用于包装,汽车和交通领域,并有望在各个领域取代石油基塑料。除了他们的环保和绿色生产,它们具有优异的物理性质。本文概述了迄今为止已经开发的竹纤维增强热塑性复合材料和热固性复合材料的力学性能,如抗拉强度,弯曲性能和冲击强度。此外,竹纤维增强热塑性复合材料在汽车上的前景,包装和农业应用。
    Natural fiber composites are receiving more and more attention because of their greenness and low cost. Among natural fibers, bamboo is characterized by fast growth, a short cultivation period, high strength and good toughness, and is one of the strongest natural fibers in the world. A bamboo-fiber-reinforced polymer composite (BFRPC) has the characteristics of high mechanical strength, low density, degradability, etc. It has the industrial applicability comparable to metal materials, the same strong corrosion resistance as composites such as glass and carbon fibers, and the same immunity to electromagnetic interference and low thermal conductivity as natural materials. Its unidirectional specific strength and unidirectional specific modulus is higher than that of glass fiber, second only to the extremely high price of carbon fiber, which is playing an increasingly important role in the field of composite materials, and can be widely used in the fields of wind power, construction, aviation, automotive, medical care and so on. At present, it has been initially used in packaging, automotive and transportation fields, and is expected to replace petroleum-based plastics in various fields. In addition to their environmental protection and green production, they have excellent physical properties. This paper provides an overview of the mechanical properties of bamboo-fiber-reinforced thermoplastic composites and thermoset composites that have been developed so far, such as tensile strength, flexural properties and impact strength. In addition, the prospects of bamboo-fiber-reinforced thermoplastic composites for automotive, packaging and agricultural applications are presented.
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  • 文章类型: Journal Article
    心血管疾病一直是全球死亡人数的主要贡献者。但是在过去的几十年中,这些数字有所下降,因为由于治疗和手术治疗方式的突破性进展,数百万人的生命得以挽救。在心脏病学中实现这一科学荣耀水平是一项具有挑战性的壮举。这归功于上个世纪的科学家和医生,尽管他们当时的技术限制,为现代医学奠定了坚实的基础。瓣膜并发症是全球心脏疾病负担的主要部分。心脏瓣膜置换术的持续发展仍然是一个令人着迷的话题,随着它的不断进步。瓣膜置换包括机械心脏瓣膜或生物假体心脏瓣膜。两种类型的瓣膜都有其优点和缺点;它们的使用主要取决于个体患者的要求。本文旨在回顾心脏瓣膜植入的演变,这篇文章的目的是赞扬科学家和医生的贡献。这篇文章强调了在寻找更耐用的材料方面的研究差距,以及在创造可普遍用于更好的患者预后的心脏瓣膜方面的进一步研究范围。
    Cardiovascular disorders have always been the top contributors to the number of mortality occurring worldwide. But the last few decades have seen a drop in those numbers as the lives of millions of people have been saved due to ground-breaking advances in both therapeutic and surgical treatment modalities. Achieving this level of scientific glory in cardiology was a challenging feat. The credit goes to the scientists and physicians of the previous century who, despite their time\'s technological limitations, made discoveries and laid a solid foundation for modern medicine. Valvular complications are a major part of the global burden of cardiac diseases. The ongoing development of heart valve replacements remains a fascinating subject, as it continues to progress. Valve replacements comprise either mechanical heart valves or bioprosthetic heart valves. Both types of valves have their merits and demerits; their usage depends mostly on individual patient requirements. This article aims to review the evolution of the implantation of heart valves, and it is the objective of this article to give credit to scientists and physicians for their contributions. The article highlights the research gaps in finding more durable materials and the scope of further research in creating a heart valve that can be universally used for better patient outcomes.
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  • 文章类型: Review
    生物力学工程师和物理学家通常使用生物骨进行生物力学研究,因为它们是活骨头的好代表。然而,使用生物骨骼面临挑战,比如成本,降解,疾病,伦理,航运,采购,storage,可变性,等。因此,Synbone®公司开发了一系列合成骨骼,这些骨骼已被生物力学研究人员用来弥补生物骨骼的一些缺点。已经有许多公开的生物力学报告使用这些骨骼替代品进行牙科,损伤,骨科,和其他应用。但是,没有以前的综述论文总结了这些合成骨的机械性能,以了解它们的一般性能或它们如何代表生物骨。因此,本文的目的是调查有关这些合成骨骼的机械性能的英语文献。如果定量地(a)表征合成骨的先前未知值,(b)经过验证的合成与生物骨,和/或(c)通过改变几何或材料参数来优化合成骨性能。这次数据审查,趋势,优点,缺点,未来的工作将有望帮助使用这些合成骨骼的生物力学工程师和物理学家开发实验测试方案和计算有限元模型。
    Biomechanical engineers and physicists commonly employ biological bone for biomechanics studies, since they are good representations of living bone. Yet, there are challenges to using biological bone, such as cost, degradation, disease, ethics, shipping, sourcing, storage, variability, etc. Therefore, the Synbone® company has developed a series of synthetic bones that have been used by biomechanical investigators to offset some drawbacks of biological bone. There have been a number of published biomechanical reports using these bone surrogates for dental, injury, orthopedic, and other applications. But, there is no prior review paper that has summarized the mechanical properties of these synthetic bones in order to understand their general performance or how well they represent biological bone. Thus, the goal of this article was to survey the English-language literature on the mechanical properties of these synthetic bones. Studies were included if they quantitatively (a) characterized previously unknown values for synthetic bone, (b) validated synthetic versus biological bone, and/or (c) optimized synthetic bone performance by varying geometric or material parameters. This review of data, pros, cons, and future work will hopefully assist biomechanical engineers and physicists that use these synthetic bones as they develop experimental testing regimes and computational models.
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  • 文章类型: Journal Article
    慢性踝关节不稳定(CAI)是常见的,禁用,代表着巨大的社会经济负担。目前的治疗选择不够有效。CAI是多方面的,然而,它通常在机械不稳定性或功能损害方面得到解决。两者有着内在的联系。必须进行基础研究,以促进包括机械和功能方面的可靠转化研究。进行了审查,以确定CAI风险因素,以纳入未来的研究,我们在这里为未来的研究提供意见和观点。
    Chronic ankle instability (CAI) is common, disabling, and represents a significant socioeconomic burden. Current treatment options are not adequately efficacious. CAI is multifaceted, yet it is commonly addressed in terms of either mechanical instability or functional impairment. Both are inherently linked. Basic research must be conducted to foster reliable translational research encompassing both mechanical and functional aspects. A review was conducted to identify CAI risk factors for inclusion in future studies, and we offer here opinions and perspectives for future research.
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  • 文章类型: Journal Article
    In the context of globalization, individuals have an increased chance of being infected by multiple viruses simultaneously, thereby highlighting the importance of developing multiplexed devices. In addition to sufficient sensitivity and rapid response, multi-virus sensing techniques are expected to offer additional advantages including high throughput, one-time sampling for parallel analysis, and full automation with data visualization. In this paper, we review the optical, electrochemical, and mechanical platforms that enable multi-virus biosensing. The working mechanisms of each platform, including the detection principle, transducer configuration, bio-interface design, and detected signals, are reviewed. The advantages and limitations, as well as the challenges in implementing various detection strategies in real-life scenarios, were evaluated. Future perspectives on multiplexed biosensing techniques are critically discussed. Earlier access to multi-virus biosensors will efficiently serve for immediate pandemic control, such as in emerging SARS-CoV-2 and monkeypox cases.
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  • 文章类型: Meta-Analysis
    目的:目前尚不清楚在运动学对齐(KA)和机械对齐(MA)膝关节置换之间是否存在功能结果的差异。这项研究的目的是对可用的I-IV级证据进行全面的系统评价和荟萃分析。
    方法:对随机对照试验和观察性研究的荟萃分析,比较患者报告的结局指标(PROMs),运动范围(ROM),采用KA和MA进行TKA的步态分析和并发症。使用JoannaBriggs研究所(JBI)关键评估工具对每项研究进行质量评估。
    结果:2014年至2022年发表的12项随机对照试验和14项观察性研究纳入最终分析。荟萃分析显示,KA的牛津膝关节评分(OKS)明显更好(p=0.02),被遗忘的联合评分(FJS)(p=0.006),膝关节社会评分(KSS)客观膝关节(p=0.03)和KSS功能活动(p=0.008)评分。然而,这些改善没有超过文献报道的最小临床重要差异(MCID)值.亚组分析显示,机器人辅助的KA-TKA具有临床上优越的FJS(p=0.0002)和KSS客观膝关节评分的趋势(p=0.10),与PSI相比。KA队列的步态和足底压力分布更接近地代表健康队列,与MA相比,KA显示出膝关节内收力矩(KAM)降低的弱关联。西安大略省和麦克马斯特大学骨关节炎指数(WOMAC)的差异,膝关节损伤和骨关节炎结果评分(KOOS),两组间的活动范围和并发症无统计学意义.
    结论:尽管KA可改善多项功能结局,这些没有达到临床意义。需要进一步的标准化大规模随机研究来提高证据质量。就目前而言,很难推荐一种哲学。
    OBJECTIVE: It is unclear whether a difference in functional outcome exists between kinematically aligned (KA) and mechanically aligned (MA) knee replacements. The aim of this study is to perform a comprehensive systematic review and meta-analysis of the available level I-IV evidence.
    METHODS: A meta-analysis of randomised controlled trials and observational studies comparing patient reported outcome measures (PROMs), range of motion (ROM), gait analysis and complications in TKA with KA and MA was performed. Quality assessment was performed for each study using the Joanna Briggs Institute (JBI) critical appraisal tools.
    RESULTS: Twelve randomised controlled trials and fourteen observational studies published between 2014 and 2022 were included in the final analysis. Meta-analysis revealed KA to have significantly better Oxford Knee Score (OKS) (p = 0.02), Forgotten Joint Score (FJS) (p = 0.006), Knee Society Score (KSS) Objective Knee (p = 0.03) and KSS Functional Activity (p = 0.008) scores. However, these improvements did not exceed the minimum clinically important difference (MCID) values reported in the literature. Subgroup analysis showed robotic assisted KA-TKA to have a clinically superior FJS (p = 0.0002) and trend towards KSS Objective Knee score (p = 0.10), compared to PSI. Gait and plantar pressure distribution of KA cohorts more closely represented healthy cohorts, and KA showed a weak association of a decreased knee adduction moment (KAM) compared to MA. Differences in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), range of motion and complications were not significant between groups.
    CONCLUSIONS: Although KA results in several improved functional outcomes, these do not reach clinical significance. Further standardised large-scale randomised studies are required to improve the quality of evidence. As it stands, it is difficult to recommend one philosophy over the other.
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  • 文章类型: Journal Article
    本系统评价的目的是提供常规技术和临床结果的概述,氧化锆在牙科领域的快速烧结和高速烧结方案。精度数据,机械和光学参数进行了评估,并与氧化锆陶瓷的临床性能有关。使用MEDLINE应用PICOS搜索策略来搜索由两名审阅者使用MeSH术语的体外和体内研究。在66项潜在相关研究中,全文共选取5篇,通过人工检索进一步检索到10篇。系统评价中包含的所有15项研究均为体外研究。机械,精度和光学性能(边缘和内部拟合,断裂强度和模量,磨损,半透明和乳光,抗老化性/水热老化)评估了3-,4-和5-YTZP氧化锆材料和常规,高速烧结协议。当速度或高速烧结方法用于3-时,机械和精度结果相似或更好,4-和5-YTZP氧化锆。当3Y-TZP与快速烧结方法一起使用时,通常会降低透明度。与二硅酸锂玻璃陶瓷相比,使用烧结程序的所有类型的氧化锆在机械上表现得更好,但是玻璃陶瓷在半透明方面显示出更好的结果。
    The aim of this systematic review was to provide an overview of the technical and clinical outcomes of conventional, speed sintering and high-speed sintering protocols of zirconia in the dental field. Data on precision, mechanical and optical parameters were evaluated and related to the clinical performance of zirconia ceramic. The PICOS search strategy was applied using MEDLINE to search for in vitro and in vivo studies using MeSH Terms by two reviewers. Of 66 potentially relevant studies, 5 full text articles were selected and 10 were further retrieved through a manual search. All 15 studies included in the systematic review were in vitro studies. Mechanical, precision and optical properties (marginal and internal fit, fracture strength and modulus, wear, translucency and opalescence, aging resistance/hydrothermal aging) were evaluated regarding 3-, 4- and 5-YTZP zirconia material and conventional, high- and high-speed sintering protocols. Mechanical and precision results were similar or better when speed or high-speed sintering methods were used for 3-, 4- and 5-YTZP zirconia. Translucency is usually reduced when 3 Y-TZP is used with speed sintering methods. All types of zirconia using the sintering procedures performed mechanically better compared to lithium disilicate glass ceramics but glass ceramics showed better results regarding translucency.
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  • 文章类型: Journal Article
    机械血栓切除术(MT)治疗M2段大脑中动脉闭塞的急性缺血性卒中(AIS)患者的安全性和益处仍不确定。
    目的探讨机械取栓对AIS患者M2闭塞与M1闭塞的益处。
    PubMed,Embase,和Cochrane图书馆数据库从开始到2021年4月进行了搜索,以识别相关文章。主要结果包括90天的功能独立性(从0-2修改Rankin评分),成功再通(脑梗死血栓切除术[TICI]2b/3),死亡率,以及使用现代血栓切除装置后症状性脑出血的发生率。生成二元变体的赔率比(ORs)。使用ReviewManager5.3软件。
    最终,共纳入14项试验,有3454名参与者注册。MT对M2闭塞的3个月功能独立率高于M1闭塞,但差异无统计学意义(OR:1.19,95%置信区间[CI]:0.98~1.46).M2闭塞的TICI2b/3评分(OR:0.71,95%CI:0.58-0.88)明显低于M1。两组的死亡率和症状性脑出血发生率相当。当比较M2和M1闭塞时,我们发现,在AIS后的改良Rankin评分(0-2)中,支架取出器和抽吸之间没有显着差异,但是对于TICI2b/3,误吸的再通率明显更高(OR:0.77,95%CI:0.61-0.96)。
    与M1遮挡相比,在这项研究中,接受MT治疗的M2闭塞患者表现出相似的临床结局.此外,在90天的功能独立性方面,支架取出器和抽吸术在治疗M2闭塞方面没有差异。然而,抽吸在M2闭塞中的再通率明显高于M1闭塞。
    The safety and benefit of mechanical thrombectomy (MT) in the treatment of acute ischemic stroke (AIS) patients with M2 segment middle cerebral artery occlusions remain uncertain.
    To investigate the benefit of mechanical thrombectomy for M2 occlusion compared with M1 occlusion in patients with AIS.
    The PubMed, Embase, and Cochrane Library databases were searched from inception to April 2021 to identify relevant articles. The main results comprised 90-day functional independence (modified Rankin Score from 0-2), successful recanalization (thrombectomy in cerebral infarction [TICI] 2b/3), mortality, and rates of symptomatic intracerebral hemorrhage after using modern thrombectomy devices. Odds ratios (ORs) were generated for binary variants. ReviewManager 5.3 software was used.
    Ultimately, a total of 14 trials were included, with 3454 participants enrolled. MT for M2 occlusion had a higher rate of 3-month functional independence than M1 occlusion, but the difference was nonsignificant (OR: 1.19, 95% confidence interval [CI]: 0.98 to 1.46). The TICI2b/3 scores (OR: 0.71, 95% CI: 0.58-0.88) in M2 occlusion were remarkably lower than those in M1. The mortality and symptomatic intracerebral hemorrhage rates were comparable between the 2 groups. When comparing M2 and M1 occlusions, we found that there was no significant difference between stent retriever and aspiration in the modified Rankin Score (0-2) after AIS, but aspiration exerted an eminently higher recanalization rate with regard to TICI2b/3 (OR: 0.77, 95% CI: 0.61-0.96).
    Compared with M1 occlusion, patients with M2 occlusion treated by MT demonstrated similar clinical outcomes in this study. Moreover, there was no difference between stent retriever and aspiration in treating M2 occlusion in terms of functional independence at 90 days. However, aspiration exerted a conspicuously higher recanalization rate in M2 occlusion than in M1 occlusion.
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