Search

Copyright of Canadian Journal of Anaesthesia / Journal Canadien d'Anesthésie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: It remains unclear whether the relationship between type 2 diabetes mellitus (T2DM) and bone mineral density (BMD) reflects causality in East Asian populations. Herein, a Mendelian randomization study conducted in East Asian population enhances the current clinical cognition that T2DM is not associated with reduction in BMD. Purpose: A Mendelian randomization (MR) approach was utilized to investigate the relationship between type 2 diabetes mellitus (T2DM) and bone mineral density (BMD) in East Asian populations. Methods: Genome-wide association study summary data from BioBank Japan were used to identify genetic variants strongly related to T2DM risk (36,614 cases and 155,150 controls) and osteoporosis (7788 cases and 204,665 controls). Heel BMD GWAS data of 1260 East Asian people from ieu open gwas project was considered as a second outcome. Inverse variance-weighted (IVW) analysis was mainly applied; MR-Egger and the weighted median were also used to obtain robust estimates. A series of sensitivity analyses including Cochran's Q test, MR-Egger regression, and leave-one-out analysis were used to detect pleiotropy or heterogeneity. Results: In the main analysis, IVW estimates indicated that T2DM significantly associated with the risk of osteoporosis (odds ratio = 0.92, 95% CI: 0.86–0.99, p = 0.016) and with higher BMD (OR: 1.25, 95% CI: 1.06–1.46, p = 6.49 × 10−3). Results of comprehensive sensitivity analysis were consistent with the main causality estimate. Horizontal pleiotropy and heterogeneity were absent in our MR study. Conclusions: T2DM is not associated with reduction in BMD in terms of genetic polymorphism in East Asian populations. [ABSTRACT FROM AUTHOR]

With the increasing depletion of shallow-earth mineral resources, deep mining will become the primary route of future mineral resources development. However, deep mining technology is a long way from being mature, and there are still a great number of issues that severely limit the growth of resources. In this paper, the acoustic emission (AE) tests of triaxially loaded and unloaded deep diorite are conducted. The results show that when confining pressure is at a low level, the failure mode of rock sample is mainly tension fracture; however as confining pressure increases, the failure mode gradually changes to shear failure. Under different stress paths, AE counting characteristics can be separated into four stages, including initial low-energy zone, pre-peak quiet zone, peak sudden burst zone and post-peak failure intensive zone (post-peak fast attenuation zone or post-peak high density zone). The damage variable is defined as the ratio of the AE count rate of a certain stage to the cumulative AE count rate of the failure process, and it accounts for the largest proportion at the stage of unloading confining pressure. In addition, when confining pressure increases, the damage variable changes from a flat growth to a rapid growth, with the abrupt transition occurring around the peak stress. [ABSTRACT FROM AUTHOR]

To study the fracture propagation and meso damage evolution law of saturated sandstone under unloading (unloading confining pressure), three unloading confining pressure tests of sandstone under different initial axial pressures were designed. By means of nuclear magnetic resonance (NMR) technology, the variation characteristics of rock porosity and T2 spectrum curves were analyzed, the relationship between damage degree and unloading confining pressure ratio was established, and the fractal characteristics of NMR were analyzed. The results show that: (1) The larger the initial axial compression, the larger the axial strain and the smaller the radial strain when unloading failure occurs. With the increase of unloading confining pressure ratio, the elastic modulus decreases, and the Poisson's ratio and strain increase. (2) T2 spectrum peak shows that the pore size increases with the increase of unloading confining pressure ratio. The larger the initial axial compression, the larger the pore size. (3) Porosity increases exponentially with the increase of unloading confining pressure ratio, in which the number of micropores continues to increase, the number of mesopores and macropores first decreases and then increases. The initial axial pressure promotes the development and expansion of pores. (4) The relationship between pore characteristics, energy and damage degree is generally consistent, and the fractal characteristics of three sizes of pores show different changing rules with the increase of unloading confining pressure ratio. Highlights: With the increase of unloading confining pressure ratio, the rock gradually changes from elastic deformation to plastic deformation. The failure of the sample is caused by the sharp increase of the number and size of pores. Porosity increases exponentially with the increase of unloading confining pressure ratio. With the increase of unloading confining pressure ratio, the number of micropores continues to increase, and the number of mesopores and macropores first decreases and then increases. [ABSTRACT FROM AUTHOR]

The development of wearable electronics urgently requires the cost-effective and scalable fabrication of high-performance pressure sensors. This work aims to develop a simple carbonization strategy to facilitate sensor sensitivity by decorating discrete nickel nanoparticles on carbonized cotton fibers (CCFs). The increased air gap between the fibers at the unloading state, as well as the enlargement of the deformation distance and the contact area between the conductive materials at the loading state, contribute to a more significant resistance change. Therefore, the sensitivity of the piezoresistive sensor is improved more than 5 times within 1 N by introducing Ni nanoparticles, and it is characterized by a rapid response (∼160 ms) and recovery (∼100 ms), wide detection range (∼20 N/∼130 kPa), and good durability (∼4000 cycles). The flexible sensor has been successfully demonstrated to monitor human movements, physical stimuli, and pressure distribution. Furthermore, the proposed device can control temperature accurately as a uniform and large-scale heater. This work reveals that the Ni@CCFs-based sensor is prospective in wearable electronics, artificial intelligence, health monitoring, medical diagnosis and treatment. [ABSTRACT FROM AUTHOR]

The method of backfill in underground mining is important for ground control as well as material recycling and energy efficiency. Even though extensive testing and field studies of backfill have been conducted, less is known about the detailed damage and fracturing that occurs directly at the rock/backfill interface. In this paper, cylindrical specimens containing an inner diameter of backfill and an outer diameter of rock (RB) were tested under triaxial compression. Acoustic emissions (AE) were used throughout testing, and X-ray computed tomography (CT) scanning was conducted before loading was applied and after the specimens had failed. The high-resolution CT images were then converted into point clouds to isolate the fractures and visualize them in three dimensions. The point clouds clearly show that fracturing occurred both in the rock and along with the contact between rock and backfill, while very little fracturing was found to occur in the backfill. Based on the point cloud and AE results, a unique evolution of fracturing is found to occur that includes two stages of shear fracturing in the rock, tensile fracturing along with the rock/backfill interface, and final tensile fracturing in the rock after delamination from the backfill, all of which contributed to the nonlinear stress–strain response. This paper presents a novel approach for investigating the initiation and propagation of 3D fractures in laboratory testing and can offer a useful reference for further studies on the mechanics of bi-material structures. [ABSTRACT FROM AUTHOR]

Taking caving mining method in Chengchao Iron Mine as engineering background, based on GPS monitoring data, deep rock mass deformation and collapse monitoring data and on-the-spot surface movement record, the collapse and movement rules of rock strata in the mining area were studied. The studies have shown the following: Underground mining has the law of delay of surface movement and jump of limit angle development. The roof caving of concealed goaf in Chengchao Iron Mine experienced the process of slow caving (caving stop) → sudden caving → slow caving (caving stop) → sudden caving. The strata movement caused by mining can be divided into the stage of overburden rock collapse in the goaf and the stage of surrounding surrounding rock dumping and failure in the goaf. In the first stage, the vertical stress plays a leading role and rock failure is shown as a regular barrel collapse. In the second stage, horizontal tectonic stress plays a leading role and the collapse mechanism of rock strata can be explained by the cantilever beam theory. According to the mechanism of strata movement analysis, strata movement of Chengchao Iron is divided into six regions: vertical subsidence area, toppling sliding zone, dumping area, deformation zone, cumulative deformation area, and undisturbed zone. The results of this paper can provide a theoretical basis for the surface movement prediction of caving mining in similar metal mine. [ABSTRACT FROM AUTHOR]

Objectives: To examine the efficacy of a 24-week Baduanjin exercise program on self-reported sleep quality and quality of life in community-dwelling elderly subjects with sleep disturbances. Methods: Community-dwelling elderly men and women meeting criteria for sleep disturbances (i.e., Pittsburgh Sleep Quality of Index (PSQI) score ≥ 5) were recruited and randomized to a Baduanjin exercise intervention group or a control group. Participants in the intervention group completed five 45-min exercise sessions per week for 24 weeks, while those in control group were instructed to maintain their usual lifestyle behaviors. Results: A total of 139 participants were enrolled and randomized. Sixty-two of 67 participants in the intervention group (response rate of 92.5%) and 57 of 72 participants (response rate of 79.6%) in the control group completed intervention and follow-up. The intervention group reported significant improvements in overall sleep quality after 24 weeks compared with those randomized to control (PSQI endpoint-to-baseline change = − 2.6 ± 4.0 vs. − 0.5 ± 4.2, time × group interaction p = 0.007). Intervention group participants had higher response rates at both week 12 (23.9% vs. 9.7%, p = 0.025) and week 24 (40.3% vs. 15.3%, p = 0.001) when compared with the control group. There was a trend that the intervention group had increased quality of life (The Short Form Health Survey [SF-36] endpoint=tobaseline change 6.3 ± 10.9 vs. 2.2 ± 10.9, time × group interaction p = 0.06) when compared with the control group. Conclusions: Baduanjin exercise is an effective and feasible approach to improve self-reported sleep quality but less likely the quality of life in community-dwelling elderly men and women with sleep disturbances. Trial registration: Effect of Baduanjin Exercise on the Elderly's Sleep; http://www.chictr.org.cn/listbycreater.aspx; ChiCTR1800014706, registered 1 January 2018. [ABSTRACT FROM AUTHOR]

As one of main layers in hybrid organic-inorganic perovskite solar cells (PSCs), electron transport materials (ETM) play an important role in getting high photoelectric conversion efficiency (PCE). Here, we investigate AlO/TiO hybrid materials as electron transmission layer in planar perovskite solar cells. The hybrid AlO/TiO material is proved to induce a better crystal quality of CHNHPbClI perovskite layer as confirmed by X-ray diffractometer (XRD). The new-formed compact rough surface of ETM is responsible for the better excited electron transmission and light absorption, thus resulting in the improvement of short-circuit current ( J ). Meanwhile, the embedded AlO plays a key role in shifting the conduction band edge of ETM, thereby leading to the improvement of photo-voltage. The optimal value is obtained with the test of sequential changing AlO/TiO concentration ratio. Compared to the device with pure TiO as ETM, the devices assembled with AlO/TiO hybrid ETM showed improvement in J (from 13.65 to 18.71 mA/cm) as well as in V (from 0.95 to 1.00 V), which brings about 27.6% enhancement in PCE based on the multifunctional hybrid TiO/ AlO ETM. [ABSTRACT FROM AUTHOR]

It is demonstrated by use of the secondary ion mass spectroscopy (SIMS) some impurities, including Si, Mg and Ca, can be doped into GaN films with depths of ten nanometer and quite high surface densities in plasma without any external bias at room-temperature (RT). The physical mechanism of plasma doping without any external bias (PDWOEB) is RT diffusion stimulated by the plasma, which is very different from that of the plasma doping method with an external bias, which was called plasma immersion ion implantation in literature, whose physical mechanism is low energy ion implantation. Stimulated by a plasma with power of 750 W in 2 min, the RT diffusion coefficients of Si, Mg and Ca in GaN obtained by fitting the complementary error function distribution with their SIMS concentration distributions are 1.3E−15, 1.9E−16 and 1.2E−16 cm/s, respectively. The RT diffusion coefficients of Si and Mg have been enhanced 18 and 22 orders of magnitude, respectively, compared with the RT extrapolation values of the high temperature diffusion coefficients reported in literature. [ABSTRACT FROM AUTHOR]

A visco-plastic rate-dependent homogenization theory for particle-reinforced composites was derived and the equivalent elastic constants and the equivalent visco-plastic parameters of these composites were obtained. A framework of homogenization theory for particle-reinforced W-Ni-Fe composites, a kind of tungsten alloy, was established. Based on the homogenization theory and a fixed-point iteration method, a unit cell model with typical microstructures of the composite was established by using dynamic analysis program. The effects of tungsten content, tungsten particle shape and particle size and interface strength on the mechanical properties and the crack propagation of the W-Ni-Fe composite are analyzed under quasi-static and dynamic loadings. The stress-strain curves of the composite are given and the relation between the macro-mechanical characteristics and the microstructure parameters is explored, which provides an important theoretical basis for the optimization of the W-Ni-Fe composites. [ABSTRACT FROM AUTHOR]

This paper takes concrete as a four-phase composite made of the intact matrix and three mutually perpendicular groups of penny-shaped micro-cracks. The intact matrix is assumed to be elastic, homogeneous and isotropic, and the micro-cracks are penny-shaped. Combined with the failure mechanism of concrete subjected to impact loading, a dynamic constitutive model for concrete is developed based on Mori-Tanaka’s average stress concept and Eshelby’s equivalent inclusion theory. Experimental results show that concrete is rate-dependent. The model predictions are in good agreement with the experimental results. The model may be used to simulate the mechanical behavior of concrete under impact loadings. [ABSTRACT FROM AUTHOR]

In China, there are an estimated 30 million people with asthma, a condition that remains poorly controlled in many patients. The INITIAL study (NCT02143739) was a 12-week, multicentre, prospective, observational study comprising 45 centres across Northern and Southern China that aimed to assess asthma severity among newly diagnosed patients as well as their prescribed medications and response to treatment. The primary objective was to evaluate asthma severity using Global Initiative for Asthma (GINA) 2006 research criteria. Secondary objectives included the distribution of asthma medication by GINA severity category and evaluation of GINA 2012-defined control levels. Medications were prescribed as per usual clinical practice. At baseline, among 4491 patients, 3.9%, 12.0%, 22.6% and 61.6% had intermittent, mild persistent, moderate persistent and severe persistent asthma, respectively. Inhaled corticosteroid/long-acting β2 agonist was the most common initial therapy in 90.2% of patients. GINA 2012-defined controlled asthma levels increased in all groups, rising from 6.1% at baseline to 43.0%, 53.8% and 67.8% at Weeks 4, 8 and 12, respectively. Most patients presented with severe persistent asthma. Newly diagnosed patients with asthma could benefit from at least 3 months of regular treatment followed by long-term pharmacological management. [ABSTRACT FROM AUTHOR]