Since the 1960s, it has been a common practice worldwide to pursue a homogeneous distribution of reinforcements within a matrix material, discontinuous metal matrix composites (DMMCs) in particular. ...Taking an overview of the worldwide activities in DMMC research, despite many favourable attributes such as improved specific strength, stiffness and superior wear resistance, DMMCs with a homogeneous microstructure tend to exhibit a very low room temperature damage tolerance even with a highly ductile matrix material such as aluminium. In this review, a range of uniquely multi-scale hierarchical structures have been successfully designed and fabricated by tailoring reinforcement distribution for DMMCs in order to obtain superior performance. A variety of specific microstructures that were developed in Al, Mg, Cu, Fe, Co and TiAl matrices indicate that there must be adequate plastic regions among the reinforcements to blunt or deflect cracks if one wants to toughen DMMCs. Following this path, aided by theoretical analyses, the most recent success is the design and fabrication of a network distribution of in situ reinforcing TiB whiskers (TiBw) in titanium matrix composites (TMCs), where a tailored three-dimensional (3D) quasi-continuous network microstructure displays significant improvements in mechanical properties. This resolves the brittleness surrounding TMCs fabricated by powder metallurgy. It is the large reinforcement-lean regions that remarkably improve the composite's ductility by bearing strain, blunting the crack and decreasing the crack-propagation rate. The fracture, strengthening and toughening mechanisms are comprehensively elucidated in order to further understand the advantages of such an inhomogeneous microstructure, and to justify the development of novel techniques to produce such inhomogeneous microstructures. This approach opens up a new horizon of research and applications of DMMCs and can be easily extended to general multi-phase composites with enhanced physical and mechanical properties.
Objectives
The aim of this study was to investigate the predictive factors for relapse of IgG4‐related disease (IgG4‐RD) and observe the long‐term clinical outcomes in patients with IgG4‐RD.
Methods
...We included in the present analysis 122 patients who were newly diagnosed with IgG4‐RD, treated with glucocorticoid (GC) monotherapy or GC and immunosuppressant combination therapy, and followed for at least 3 years. Clinical relapse, response and side effects were recorded.
Results
The cumulative relapse rates of patients in this study were 10.66%, 22.95% and 27.87% at 12, 24 and 36 months, respectively. Complete drug withdrawal was an independent risk factor for disease relapse. Higher serum IgG4 concentrations, involvement of more organs, higher IgG4 RI scores and elevation of eosinophils at baseline were closely associated with disease relapse. Re‐elevation of serum IgG4 concentrations and low GC maintenance dosage during the follow‐up period were significantly associated with clinical relapse. The GC dosage should be more than 6.25 mg day−1 as monotherapy during the maintenance stage; moreover, combining with immunosuppressants can reduce the GC dosage. Adding GC or immunosuppressants for patients with re‐elevation of serum IgG4 levels could prevent later disease relapse. No serious complications were noted during long‐term follow‐up.
Conclusions
The combination of GC with immunosuppressants was more effective than GC monotherapy during the steroid tapering and maintenance stages. Higher serum IgG4 levels, involvement of more organs, higher IgG4 RI scores, history of allergy, eosinophil elevation at baseline, re‐elevation of serum IgG4 levels and lower GC maintenance dosage at follow‐up might be predictive of relapse.
This systematic review and meta-analysis estimated the global, regional prevalence, and risk factors of osteoporosis. Prevalence varied greatly according to countries (from 4.1% in Netherlands to ...52.0% in Turkey) and continents (from 8.0% in Oceania to 26.9% in Africa). Osteoporosis is a common metabolic bone disorder in the elderly, usually resulting in bone pain and an increased risk of fragility fracture, but few summarized studies have guided global strategies for the disease. Therefore, we pooled the epidemiologic data to estimate the global, regional prevalence, and potential risk factors of osteoporosis. We conducted a comprehensive literature search through PubMed, EMBASE, Web of Science, and Scopus, to identify population-based studies that reported the prevalence of osteoporosis based on the World Health Organization (WHO) criteria. Meta-regression and subgroup analyses were used to explore the sources of heterogeneity. The study was registered in the PROSPERO database (CRD42021285555). Of the 57,933 citations evaluated, 108 individual studies containing 343,704 subjects were included. The global prevalence of osteoporosis and osteopenia was 19.7% (95%CI, 18.0%–21.4%) and 40.4% (95%CI, 36.9%–43.8%). Prevalence varied greatly according to countries (from 4.1% in Netherlands to 52.0% in Turkey) and continents (from Oceania 8.0% to 26.9% in Africa). The prevalence was higher in developing countries (22.1%, 95%CI, 20.1%–24.1%) than in developed countries (14.5%, 95%CI, 11.5%–17.7%). Our study indicates a considerable prevalence of osteoporosis among the general population based on WHO criteria, and the prevalence varies substantially between countries and regions. Future studies with robust evidence are required to explore risk factors to provide effective preventive strategies for the disease.
Application of graphene derived nanomaterial in microwave absorption has been limited by the issue of excessively high dielectric loss. To address this issue, instead of resorting to burdensome ...compositing with metal and ceramic particles, we put forward the idea of approaching impedance match by transforming graphene from diamagnetic to ferromagnetic and meanwhile suppress the conductivity. In this study, we synthesized the Nitrogen-doped graphene (NG) by a facile hydrothermal method with graphene oxide (GO) and urea as precursors. In comparison with GO and reduced GO (rGO), the nitrogen doping along with reduction process boosted the magnetism via a Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism. Pyrrolic-N has been found to dominate the magnetic property induced, which cooperates with the suppression of conductivity to benefit the absorption performance. The reflection loss of nitrogen doped graphene can achieve −11.3 dB absorption maximum at 12.7 GHz and an absorption bandwidth of 12.2–14.3 GHz (reflection loss < −10 dB) at a thickness of 3 mm, which proves to be favourable with respective to the density as compared to existing graphene-based absorbers.
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The gas diffusion layer (GDL) in a proton exchange membrane fuel cell (PEMFC) is one of the functional components that provide a support structure for gas and water transport. The GDL plays a crucial ...role when the oxidant is air, especially when the fuel cell operates in the higher current density region. There has been an exponential growth in research and development because the PEMFC has the potential to become the future energy source for automotive applications. In order to serve in this capacity, the GDL requires due innovative analysis and characterization toward performance and durability. It is possible to achieve the optimum fuel cell performance only by understanding the characteristics of GDLs such as structure, pore size, porosity, gas permeability, wettability, thermal and electrical conductivities, surface morphology and water management. This review attempts to bring together the characterization techniques for the essential properties of the GDLs as handy tools for R&D institutions. Topics are categorized based on the ex-situ and in-situ characterization techniques of GDLs along with related modeling and simulation. Recently reported techniques used for accelerated durability evaluation of the GDLs are also consolidated within the ex-situ and in-situ methods.
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► This Manuscript deals with Gas Diffusion Layer characterization tools. ► Ex-situ and in-situ methods are identified and grouped. ► Techniques for electrical, thermal, mechanical, surface, bulk properties and durability are discussed.
Recent studies indicate that intestinal oxidative stress and microbiota imbalance is involved in weaning-induced intestinal dysfunction in piglets. We have investigated the effect of feeding a ...carvacrol-thymol blend supplemented diet on intestinal redox status, selected microbial populations and the intestinal barrier in weaning piglets. The piglets (weaned at 21 days of age) were randomly allocated to two groups with six pens per treatment and 10 piglets per pen. At weaning day (21 days of age), six piglets were sacrificed before weaning to serve as the preweaning group. The weaned group was fed with a basal diet, while the weaned-CB group was fed with the basal diet supplemented with 100 mg/kg carvacrol-thymol (1 : 1) blend for 14 days. On day 7 post-weaning, six piglets from each group were sacrificed to determine intestinal redox status, selected microbial populations, messenger RNA (mRNA) transcript levels of proinflammatory cytokines and biomarkers of intestinal barrier function. Weaning resulted in intestinal oxidative stress, indicated by the increased concentration of reactive oxygen species and thiobarbituric acid-reactive substances present in the intestine. Weaning also reduced the population of Lactobacillus genus and increased the populations of Enterococcus genus and Escherichia coli in the jejunum, and increased mRNA levels of tumor necrosis factor α (TNF-α), interleukin 1β and interleukin 6 (IL-6). In addition, decreased mRNA levels of zonula occludens and occludin in the jejunal mucosa and increased plasma diamine oxidase concentrations indicated that weaning induced dysfunction of the intestinal barrier. On day 7 post-weaning, supplementation with the carvacrol-thymol blend restored weaning-induced intestinal oxidative stress. Compared with the weaned group, the weaned-CB group had an increased population of Lactobacillus genus but reduced populations of Enterococcus genus and E. coli in the jejunum and decreased mRNA levels of TNF-α. The results indicated that weaning induced intestinal oxidative stress and dysfunction of the intestinal barrier. Dietary supplementation with 100 mg/kg carvacrol-thymol (1 : 1) decreased the intestinal oxidative stress and influenced selected microbial populations without changing the biomarkers of intestinal barrier in weaning piglets.
Summary
Peri‐operative dexmedetomidine can reduce rates of delirium immediately after surgery. We aimed to assess the effect of dexmedetomidine on cognition up to six postoperative months and its ...association with changes in serum concentrations of brain‐derived neurotrophic factor on the third and seventh postoperative days. We randomly allocated 535 patients aged 65 years or more undergoing scheduled gastro‐intestinal laparotomy to: intra‐operative dexmedetomidine, 0.5 μg.kg−1 bolus followed by 0.4 μg.kg−1.hr−1 infusion (n = 269), or placebo (n = 266). Dexmedetomidine reduced the rate of cognitive impairment: on the third postoperative day, 40/269 vs. 65/266, p = 0.006; on the seventh postoperative day, 31/269 vs. 49/266, p = 0.03 and at one postoperative month, 42/250 vs. 61/248, p = 0.04. Cognitive impairment at seven postoperative days was associated with changes in brain‐derived neurotrophic factor concentrations on the third and seventh postoperative days; area under the receiver operating characteristic curve 0.63, p < 0.001 and 0.58, p = 0.016, respectively. Intra‐operative dexmedetomidine reduced cognitive decline up to one postoperative month in elderly patients undergoing scheduled laparotomy, which was associated with changes in serum brain‐derived neurotrophic factor.
This REgional Carbon Cycle Assessment and Processes regional study provides a synthesis of the carbon balance of terrestrial ecosystems in East Asia, a region comprised of China, Japan, North and ...South Korea, and Mongolia. We estimate the current terrestrial carbon balance of East Asia and its driving mechanisms during 1990–2009 using three different approaches: inventories combined with satellite greenness measurements, terrestrial ecosystem carbon cycle models and atmospheric inversion models. The magnitudes of East Asia's terrestrial carbon sink from these three approaches are comparable: −0.293±0.033 PgC yr−1 from inventory–remote sensing model–data fusion approach, −0.413±0.141 PgC yr−1 (not considering biofuel emissions) or −0.224±0.141 PgC yr−1 (considering biofuel emissions) for carbon cycle models, and −0.270±0.507 PgC yr−1 for atmospheric inverse models. Here and in the following, the numbers behind ± signs are standard deviations. The ensemble of ecosystem modeling based analyses further suggests that at the regional scale, climate change and rising atmospheric CO2 together resulted in a carbon sink of −0.289±0.135 PgC yr−1, while land-use change and nitrogen deposition had a contribution of −0.013±0.029 PgC yr−1 and −0.107±0.025 PgC yr−1, respectively. Although the magnitude of climate change effects on the carbon balance varies among different models, all models agree that in response to climate change alone, southern China experienced an increase in carbon storage from 1990 to 2009, while northern East Asia including Mongolia and north China showed a decrease in carbon storage. Overall, our results suggest that about 13–27% of East Asia's CO2 emissions from fossil fuel burning have been offset by carbon accumulation in its terrestrial territory over the period from 1990 to 2009. The underlying mechanisms of carbon sink over East Asia still remain largely uncertain, given the diversity and intensity of land management processes, and the regional conjunction of many drivers such as nutrient deposition, climate, atmospheric pollution and CO2 changes, which cannot be considered as independent for their effects on carbon storage.
Nature inspired flow field designs for proton exchange membrane fuel cells (PEMFCs) are a relatively recent development in the technology evolution. These novel designs have the potential to show ...dramatic performance improvements by effective distribution of reactant gases without water flooding. Optimization of a flow field requires balancing gas distribution, water management, electron transport, pressure drop and manufacturing simplicity. Computational fluid dynamics (CFD) simulation studies are a useful tool for evaluating nature inspired flow field designs; however, the predictions should be used with caution until validated by an experimental study. Nature inspired flow field designs can be generated using formal mathematical algorithms or by making heuristic modifications to existing natural structures. This paper reviews the current state of nature inspired PEMFC flow field designs and discusses the challenges in evaluating these designs.
► This manuscript deals with the trend on flow field design in the recent years. ► CFD modeling is a useful design tool but limitations should be understood. ► Nature inspired designs are one of the potential optimization approaches.
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