Compression, tension and high-velocity plate impact experiments were performed on a typical tough Zr
41.2
Ti
13.8
Cu
10
Ni
12.5
Be
22.5
(Vit 1) bulk metallic glass (BMG) over a wide range of strain ...rates from ∼10
−4
to 10
6
s
−1
. Surprisingly, fine dimples and periodic corrugations on a nanoscale were also observed on dynamic mode I fracture surfaces of this tough Vit 1. Taking a broad overview of the fracture patterning of specimens, we proposed a criterion to assess whether the fracture of BMGs is essentially brittle or plastic. If the curvature radius of the crack tip is greater than the critical wavelength of meniscus instability F. Spaepen, Acta Metall. 23 615 (1975); A.S. Argon and M. Salama, Mater. Sci. Eng. 23 219 (1976), microscale vein patterns and nanoscale dimples appear on crack surfaces. However, in the opposite case, the local quasi-cleavage/separation through local atomic clusters with local softening in the background ahead of the crack tip dominates, producing nanoscale periodic corrugations. At the atomic cluster level, energy dissipation in fracture of BMGs is, therefore, determined by two competing elementary processes, viz. conventional shear transformation zones (STZs) and envisioned tension transformation zones (TTZs) ahead of the crack tip. Finally, the mechanism for the formation of nanoscale periodic corrugation is quantitatively discussed by applying the present energy dissipation mechanism.
Laser-induced breakdown spectroscopy (LIBS) technology has been applied to many fields, so it is crucial for quantitative analyses of LIBS spectra. However, there is a problem in the field of LIBS ...spectra. Even in the same experimental setting, the same sample exhibits different spectra with different instruments, which is mainly reflected in the intensity, wavelength shift, and peak width differences. These differences cause standardization problems in LIBS spectroscopy and serious interference in quantitative analyses. The aim of this study is to correct the difference by applying the extreme learning machine method and the deep extreme learning machine method to two different spectral datasets. The first dataset is the ChemCam calibration target sample set, which contains two spectral datasets produced by using ChemCam on instruments on the Curiosity rover and at the Mars Science Laboratory (MSL). The other dataset comprises spectra obtained from calibration target samples produced by the ChemCam team at MSL. The performance of the two algorithms is tested, and the results show that our calibration transfer methods are stable predictive methods that provide significantly lower prediction error compared with linear transfer and the piecewise direct standardization method. The model established by the partial least square method is used for quantitative analyses of the transferred spectra, and the transmitted spectra showed improved quantitative accuracy.
To investigate whether modification of liver complement factor H (CFH) production, by alteration of liver CFH Y402H genotype through liver transplantation (LT), influences the development of ...age-related macular degeneration (AMD).
Multicenter, cross-sectional study.
We recruited 223 Western European patients ≥ 55 years old who had undergone LT ≥ 5 years previously.
We determined AMD status using a standard grading system. Recipient CFH Y402H genotype was obtained from DNA extracted from recipient blood samples. Donor CFH Y402H genotype was inferred from recipient plasma CFH Y402H protein allotype, measured using enzyme-linked immunosorbent assays. This approach was verified by genotyping donor tissue from a subgroup of patients. Systemic complement activity was ascertained by measuring levels of plasma complement proteins using an enzyme-linked immunosorbent assay, including substrates (C3, C4), activation products (C3a, C4a, and terminal complement complex), and regulators (total CFH, C1 inhibitor).
We evaluated AMD status and recipient and donor CFH Y402H genotype.
In LT patients, AMD was associated with recipient CFH Y402H genotype (P = 0.036; odds ratio OR, 1.6; 95% confidence interval CI, 1.0-2.4) but not with donor CFH Y402H genotype (P = 0.626), after controlling for age, sex, smoking status, and body mass index. Recipient plasma CFH Y402H protein allotype predicted donor CFH Y402H genotype with 100% accuracy (n = 49). Plasma complement protein or activation product levels were similar in LT patients with and without AMD. Compared with previously reported prevalence figures (Rotterdam Study), LT patients demonstrated a high prevalence of both AMD (64.6% vs 37.1%; OR, 3.09; P<0.001) and the CFH Y402H sequence variation (41.9% vs 36.2%; OR, 1.27; P = 0.014).
Presence of AMD is not associated with modification of hepatic CFH production. In addition, AMD is not associated with systemic complement activity in LT patients. These findings suggest that local intraocular complement activity is of greater importance in AMD pathogenesis. The high AMD prevalence observed in LT patients may be associated with the increased frequency of the CFH Y402H sequence variation.
The authors have no proprietary or commercial interest in any materials discussed in this article.
To reveal the mechanism of a void-dominated fracture process in bulk metallic glasses, a theoretical description of void growth undergoing remote hydrostatic tension is presented. Special attention ...is focused on cavitation instabilities and dynamics of a dynamic void growth process. The critical stress for cavitation instabilities is derived theoretically, which is validated by numerical simulations with a finite difference method. To characterize the dynamic void growth process, a dimensionless number is proposed, which embodies the competition of inertial effects, loading rate effects and viscous effects. It is found that inertial effects can induce vibration of the void growth rate at the rise stage of loading history and impede the growth at the steady stage. In addition, to study the void growth at the early stage of a void-dominated fracture process, quasistatic cases without inertial effects are examined. It is shown that the void growth rate strongly depends on the evolution of free volume concentration.
Research on the contextual antecedents of employee silence remains underdeveloped. We propose supervisors’ coercive and reward power as important antecedents of employee silence. Furthermore, guided ...by the person–environment interaction perspective, we suggest that two employee personality traits – conscientiousness and neuroticism – moderate the relationship between perceived supervisor power and employee silence. We conducted a two-wave survey of 177 full-time employees in China and found that employees were (a) more likely to remain silent when they perceived that their supervisor had high coercive power and (b) less likely to remain silent when they perceived that their supervisor had high reward power. These relationships were stronger for employees with a low level of conscientiousness or a high level of neuroticism. We discuss the theoretical and practical implications of our findings.
Vascular inflammation is well known for its ability to compromise the function of the blood–brain barrier (BBB). Whether inflammation on the parenchymal side of the barrier, such as that associated ...with Parkinson's‐like dopamine (DA) neuron lesions, similarly disrupts BBB function, is unknown. We assessed BBB integrity by examining the leakage of FITC‐labeled albumin or horseradish peroxidase from the vasculature into parenchyma in animals exposed to the DA neurotoxin 6‐hydroxydopamine (6OHDA). Unilateral injections of 6OHDA into the striatum or the medial forebrain bundle produced increased leakage in the ipsilateral substantia nigra and striatum 10 and 34 days following 6OHDA. Microglia were markedly activated and DA neurons were reduced by the lesions. The areas of BBB leakage were associated with increased expression of P‐glycoprotein and β3‐integrin expression suggesting, respectively, a compensatory response to inflammation and possible angiogenesis. Behavioural studies revealed that domperidone, a DA antagonist that normally does not cross the BBB, attenuated apomorphine‐induced stereotypic behaviour in animals with 6OHDA lesions. This suggests that drugs which normally have no effect in brain can enter following Parkinson‐like lesions. These data suggest that the events associated with DA neuron loss compromise BBB function.
Summary
E‐cadherin is a 120‐KD transmembrane calcium‐dependent cell adhesion protein that has been demonstrated drownregulated in a large amount of invasive tumors. However, its effect on the ...prognosis of esophageal cancer (EC) remains controversial. All the relevant English articles that reported survival data or clinicopathological parameters were enrolled in this meta‐analysis. A total of 24 studies, including 2691 cases, were included in this study. Twelve studies containing 1669 cases were enrolled to synthesize with hazard ratio (HR) and its 95% confidence interval (CI). The pooled HR for all 12 studies enrolled in this meta‐analysis was 1.33 (95% CI 1.16–1.52; z = 3.99, P = 0.00). When the study measured by enzyme‐linked immunosorbent assay is excluded, the pooled HR‐evaluated E‐cadherin to reduce the expression in EC, and in esophageal squamous cell carcinoma was 1.39 (95% CI 1.22–1.58; z = 5.08, P = 0.00) and 1.38 (95% CI 1.21–1.56; z = 4.87, P = 0.00), respectively. The risk of reduced E‐cadherin expression on poor differentiation degree was 1.636 (95% CI 1.33–2.02). The pooled odds ratio of reduced E‐cadherin expression on deeper tumor invasion, lymph node metastasis, and higher clinical stage were 2.63 (95% CI 1.75–3.94), 1.77 (95% CI 1.06 −2.97), and 3.39 (95% CI 1.85–6.23). Reduced E‐cadherin expression detected by immunohistochemistry could be a valid prognostic marker in patients with EC, especially in patients with esophageal squamous cell carcinoma. Reduced E‐cadherin expression is significantly associated with poorer differentiation degree.
► Experiments are conducted in a Ported Optical Engine with large skip-firing ratio. ► Turbulence statistics is distinguished for fast, average and slow combustion events. ► A clear link is shown ...between the variability of turbulence and rate of combustion. ► Faster combustion corresponds to higher values of root-mean-square velocity. ► Faster combustion corresponds to higher root-mean-square rather than mean vorticity.
An investigation is carried out into the connection between the various characteristics of the velocity field and the burning rate in a spark-ignition engine. The experiments are performed on the Leeds University Ported Optical Engine with a large skip-firing ratio; the engine allows a full optical access to the combustion chamber. Velocity fields are obtained using a Particle Image Velocimetry (PIV) and a systematic distinct averaging is performed with an account of the cyclic variability of the burning rate, that is the properties of the turbulent velocity fields are derived separately for the fast, middle and slow cycles using the peak pressure as a proxy measure for the burning rate. Even though the velocity fields are nearly homogeneous in the mean, they reveal very significant intermittency where the regions of intense fluctuations have an extent more than half the clearance height. It is shown that the variations of the burning rate are correlated with the fluctuations in root-mean-square fields of the velocity magnitude, vorticity and shear strain rate. Faster combustion is induced by the fields with larger root-mean-square values. No discernible correlation of the burning rate with the average vorticity or shear strain fields has been detected. The integral scales of the large-scale motion derived from the PIV do not show any systematic variation between fast and slow cycles.
The prevalence of workaholism has negative consequences on human health. Lack of sleep, a well-known problem among adults in modern society, is often attributed to overwork as a result of ...workaholism. Yet there is a lack of empirical research examining how and when workaholism will lead to sleep problems. To answer this question and to examine the longitudinal effect of workaholism on sleep in China, we investigate the mediating role of perceived evening responsibilities of work and the moderating effect of work autonomy. Two hundred and five Chinese working adults (58.0% female) voluntarily completed the online questionnaires at Time 1 (T1) and Time 2 (T2; 1-month later). Results showed that workaholism at T1 had a significant and positive correlation with sleep problem at T2. Further analysis suggested that perceived evening responsibilities of work fully mediated the relationship between workaholism and sleep problem. Work autonomy was shown to buffer the positive effect of workaholism on perceived evening responsibilities of work and attenuate the indirect effect of workaholism on sleep problem. While workers should be made aware of the negative impact of workaholism on sleep, organizations should also consider interventions to enhance employees’ autonomy and control of their work.
A new Venus‐ESD‐Chamber (VEC) and peripheral systems were designed and built to simulate Venus lightning. It consists of three subsystems (a) electrostatic discharge (ESD) generation, (b) ...environmental pressure, temperature, gas composition control & monitoring, and (c) optical and non‐optical sensors. We conducted arc discharge experiments in air, in CO2, and in Venus major gas mixture (CO2‐N2, 96.5% ± 1.5%:3.5% ± 1.5%) under 10, 350, 700, and 1,000 mbar pressures, that correspond to the 50–75 km altitude range in the cloud layer of Venus. Plasma and Raman spectra, plus gas sensors, and GC‐MS were used to identify the ESD products and to semi‐quantify CO and O3 generated by ESD. We have found all species of free radicals that have been found in previous simulation studies using different discharge technologies, including some important species in CO2‐N2 system, nitrogen oxides and CN. In addition, we found three species (O3, N2+, and C2) that have not been previously reported. Our results suggest that electron flux and kinetic energy are the determining factors for the type of generated free radical species and gas pressure plays a less important role. We found that the quantity of CO changes with the type of ESD. The detection of O3 in this study suggests that lightning might be one of the sources of O3 observed in the Venusian atmosphere. OI emission line at 777.4 nm is the most prominent line in our plasma spectra of FD, consistent with the intense optical flash observed by the Lightning and Airglow Camera (LAC) on the Akatsuki mission.
Plain Language Summary
Lightning is a common phenomenon on Earth and plays an important role in atmospheric chemistry as well as in atmosphere‐surface interaction. The thick atmosphere and strong convective activities in Venus cloud layers could ignite lightning. Evidence of lightning on Venus (optical and electric types) has been reported since the 1970s, including the observation made by the most recent mission Akatsuki in 2020. Here, we report the detection of 15 types of free radicals generated during a set of arc‐type electric discharges in simulated Venus atmosphere with two major Venus gases (CO2 & N2) and in a pressure range corresponding to the Venus cloud layer (50–75 km altitude range). These free radicals are ions and neutral atoms/molecules in excited states, which have extremely high chemical reactivity and high kinetic energy. They could play crucial roles in Venus atmospheric chemistry and might be helpful to interpret some past mission observations for example, nitrogen oxides and O3.
Key Points
Building a Venus‐ESD chamber enables simulation of Venus lightning and radical sensing
Arc discharge was realized to simulate lightning in the cloud layer of Venus
15 types of free radicals and excited atoms/molecules were characterized using four sensors
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