Are Ceramic Bearings Becoming Cost-Effective for All Patients?

Background

The purpose of this study is to analyze whether the cost for ceramic-on-polyethylene (C-PE) and ceramic-on-ceramic (COC) bearings used in primary total hip arthroplasty (THA) was changing over time, and if the cost differential between ceramic bearings and metal-on-polyethylene (M-PE) bearings was approaching the previously published tipping point for cost-effectiveness of $325.

Conductance enlargement in picoscale electroburnt graphene nanojunctions

Provided the electrical properties of electroburnt graphene junctions can be understood and controlled, they have the potential to underpin the development of a wide range of future sub-10-nm electrical devices. We examine both theoretically and experimentally the electrical conductance of electroburnt graphene junctions at the last stages of nanogap formation. We account for the appearance of a counterintuitive increase in electrical conductance just before the gap forms. This is a manifestation of room-temperature quantum interference and arises from a combination of the semimetallic band structure of graphene and a cross-over from electrodes with multiple-path connectivity to single-path connectivity just before breaking. Therefore, our results suggest that conductance enlargement before junction rupture is a signal of the formation of electroburnt junctions, with a picoscale current path formed from a single sp² bond.Graphene nanojunctions are attractive as electrodes for electrical contact to single molecules (1–7), due to their excellent stability and conductivity up to high temperatures and a close match between their Fermi energy and the HOMO (highest occupied molecular orbital) or LUMO (lowest unoccupied molecular orbit) energy levels of organic materials. Graphene electrodes also facilitate electrostatic gating due to their reduced screening compared with more bulky metallic electrodes. Although different strategies for forming nanogaps in graphene such as atomic force microscopy, nanolithography (8), electrical breakdown (9), and mechanical stress (10) have been used, only electroburning delivers the required gap-size control below 10 nm (11–13). This new technology has the potential to overcome the challenges of making stable and reproducible single-molecule junctions with gating capabilities and compatibility with integrated circuit technology (14) and may provide the breakthrough that will enable molecular devices to compete with foreseeable developments in Moore’s law, at least for some niche applications (15–17).One set of such applications is likely to be associated with room-temperature manifestations of quantum interference (QI), which are enabled by the small size of these junctions. If such interference effects could be harnessed in a single-molecule device, this would pave the way toward logic devices with energy consumption lower than the current state-of-the-art. Indirect evidence for such QI in single-molecule mechanically controlled break junctions has been reported recently in a number of papers (18), but direct control of QI has not been possible because electrostatic gating of such devices is difficult. Graphene electroburnt junctions have the potential to deliver direct control of QI in single molecules, but before this can be fully achieved, it is necessary to identify and differentiate intrinsic manifestations of room-temperature QI in the bare junctions, without molecules. In the present paper, we account for one such manifestation, which is a ubiquitous feature in the fabrication of picoscale gaps for molecular devices, namely an unexpected increase in the conductance before the formation of a tunnel gap.Only a few groups in the world have been able to implement electroburning method to form nanogap-size junctions. In a recent study of electroburnt graphene junctions, Barreiro et al. (19) used real-time in situ transmission electron microscopy (TEM) to investigate this conductance enlargement in the last moment of gap formation and ruled out the effects of both extra edge scattering and impurities, which reduce the current density near breaking. Also, they showed that the graphene junctions can be free of contaminants before the formation of the nanogap. Having eliminated these effects, they suggested that the enlargement may arise from the formation of the seamless graphene bilayers. Here we show that the conductance enlargement occurs in monolayer graphene, which rules out an explanation based on bilayers. Moreover, we have observed the enlargement in a large number of nominally identical graphene devices and therefore we can rule out the possibility of device- or flake-specific features in the electroburning process. An alternative explanation was proposed by Lu et al. (20), who observed the enlargement in few-layer graphene nanoconstrictions fabricated using TEM. They attributed the enlargement to an improvement in the quality of few-layer graphene due to current annealing, which was simply ruled out by our experiments on electroburnt single-layer graphene. They also attributed this to the reduction of the edge scattering due to the orientation of the edges (i.e., zigzag edges). However, such edge effects have been ruled out by the TEM images of Barreiro et al. (19). Therefore, although this enlargement appears to be a common feature of graphene nanojunctions, so far the origin of the increase remains unexplained.In what follows, our aim is to demonstrate that such conductance enlargement is a universal feature of electroburnt graphene junctions and arises from QI at the moment of breaking. Graphene provides an ideal platform for studying room-temperature QI effects (21) because, as well as being a suitable material for contacting single molecules, it can serve as a natural 2D grid of interfering pathways. By electroburning a graphene junction to the point where only a few carbon bonds connect the left and right electrodes, one can study the effect of QI in ring- and chain-like structures that are covalently bonded to the electrodes. In this paper, we perform feedback-controlled electroburning on single-layer graphene nanojunctions and confirm that there is an increase in conductance immediately before the formation of the tunnel junction. Transport calculations for a variety of different atomic configurations using the nonequilibrium Green’s function (NEGF) method coupled to density functional theory (DFT) show a similar behavior. To elucidate the origin of the effect, we provide a model for the observed increase in the conductance based on the transition from multipath connectivity to single-path connectivity, in close analogy to an optical double-slit experiment. The model suggests that the conductance increase is likely to occur whenever junctions are formed from any sp²-bonded material.     

High-sensitivity Troponin I Predicts Galectin-3 in Chronic Kidney Disease Patients

International Urology and Nephrology - Plasma galectin-3 (pG3) regulates inflammation. B-type natriuretic peptide (BNP), high-sensitivity Troponin I (hsTnI), and pG3 concentrations are elevated in...     

肝胆外科从数字虚拟人、三维可视化到数字智能化发展的现状

数字智能化肝胆外科的发展经历了十几年的演进过程,从数字虚拟人技术到质控化、同质化三维可视化精准诊疗体系的建立;从三维可视化到数字智能化技术临床转化及诊疗模式的转换;实现了疾病的经验性诊断到深度学习智能化诊断与治疗和经验性手术到多模态影像实时手术导航的技术创新;从肿瘤的形态学诊断深入到分子影像学精准诊断的研究。在这个过程中只有不断地进行研究创新、理论创新和技术创新才能给数字智能化外科赋予新的生命力。未来,从关键分子功能可视化实现肝癌分子、细胞层面边界界定和早诊早治,对改变肝癌患者肝切除术后的预后具有重大的临床价值。此外,为了实现智能化肝切除手术导航,突破技术瓶颈,研发具有自动导航技术、机器学习智能规划技术和多模态影像融合技术的智能化机器人实时导航肝切除手术系统具有重要的临床意义,给数字智能化肝胆外科的发展带来了新的机遇和挑战。     

MRI radiomics to differentiate between low grade glioma and glioblastoma peritumoral region

Journal of Neuro-Oncology - Primary malignant spinal astrocytomas present rare oncological entities with limited median survival and rapid neurological deterioration. Evidence on surgical therapy,...     

Implementing an i.v. iron maintenance regimen protocol in a hemodialysis practice.

Iron-deficiency anemia is commonly encountered in patients with end-stage renal disease (ESRD) requiring chronic hemodialysis and can occur as a result of blood loss from frequent laboratory tests, blood retention in the dialysis tubing and dialyzer, gastrointestinal (GI) bleeding, repeated access surgery, poor oral iron intake and/or absorption, and low protein diets (Sakiewicz, 1998; Eschbach, 1999). Further compounding the deficiency is the use of recombinant human erythropoietin (EPO), which stimulates erythropoiesis to abnormally high levels and leads to functional iron deficiency in up to 90% of patients (Macdougall, 1995; Sunder-Plassmann, 1997).     

A preliminary reliability and validity study of the Chinese version of the self-efficacy for exercise scale for older adults

Background

Population ageing affects most undeveloped, developing and developed countries. Less than a quarter of older people undertake a level of physical activity worldwide that is sufficient to lead to health benefits. Understanding older people’s confidence regarding engaging in exercise helps to structure physical activity interventions that motivate them to initiate and adhere to regular exercise. Estimates of the reliability and validity of the English version of the self-efficacy for exercise (SEE) scale has been widely tested and shown to be valid for use in various settings and among older people. The reliability and validity of a Chinese version of the SEE for older adults has not been tested.

Aim

To undertake a preliminary assessment of the reliability and validity of the SEE scale when applied to the older Chinese adults.

Methods

The Chinese version of the self-efficacy for exercise (SEE-C) scale was tested on a sample of 192 older people from Taiwan with a mean age of 71.2 years recruited between October and December 2003.

Results

There was acceptable internal consistency of the SEE-C scale. The fit of the measurement model to the data for the SEE-C scale was acceptable. There was evidence of validity of the measure based on hypothesis testing: health status predicted exercise self-efficacy, and exercise self-efficacy predicted physical activity. Those who exercised regularly (n = 102) had a higher mean SEE-C score (5.3) than those who did not (2.9, n = 90).

Conclusion

This preliminary validation study provided evidence for the reliability and validity of the Chinese version of the SEE scale. Future testing of the SEE-C scale needs to be carried out to see whether these results are generalisable to older Chinese people living in urban areas and with different characteristics. A test of the scale among younger adults for a wider use of the instrument is also warranted.