Summary
Background
Interventional treatment for overt hepatic encephalopathy (OHE), includes non‐absorbable disaccharides, neomycin, rifaximin, L‐ornithine‐L‐aspartate and branched chain amino acids ...(BCAA). However, the optimum regimen remains inconclusive.
Aim
To compare interventions in terms of patients’ adverse events and major clinical outcomes.
Methods
Literature search of PubMed, Embase, Scopus, and Cochrane Library studies published up to July 31 2014. RCTs of above interventions in OHE patients were included. Network meta‐analysis combined direct and indirect evidence to estimate odds ratios (ORs) and mean difference (MD) between treatments and the probabilities of ranking for treatment based on clinical outcomes.
Results
Twenty eligible RCTs were included. When compared with observation, only L‐ornithine‐L‐aspartate (OR 3.71, P < 0.001) and BCAA (OR 3.37, P < 0.001) improved clinical efficacy significantly. However, when L‐ornithine‐L‐aspartate was compared with BCAA, non‐absorbable disaccharides and neomycin, there was a trend suggesting that L‐ornithine‐L‐aspartate may be the most effective intervention with respect to clinical improvement (OR 1.10), rifaximin (OR 1.31), non‐absorbable disaccharides (OR 2.75), neomycin (OR 2.22). In addition, L‐ornithine‐L‐aspartate (MD −20.18, 95% CI −40.12 to −0.27) provided a significant reduction in blood ammonia concentration compared with observation. Neomycin appeared to be associated with more adverse events in comparison with non‐absorbable disaccharides (OR 10.15), rifaximin (OR 17.31), L‐ornithine‐L‐aspartate (OR 3.16) or BCAA (OR 7.69).
Conclusions
L‐ornithine‐L‐aspartate treatment may show a trend in superiority for clinical efficacy among standard interventions for OHE. Rifaximin shows the greatest reduction in blood ammonia concentration, and treatment with neomycin demonstrates a higher probability in causing adverse effects among the five compared interventions.
Composite structures made of 2 mm-thick titanium and 10 mm-thick carbon steel are widely used in infrastructures such as long-distance gas transportation. However, cracking, which is caused by ...intermetallic compounds (ICs), is a dominate failure mode in welds of this structure. Thus, a common way to improve the in-service life of is reduce the number of ICs. In this paper, we employ a novel hybrid welding method to fabricate composite structures of TA
titanium and Q235 carbon steel. Specifically, Ti and carbon steel is welded by laser and double Cold Metal Transfer (CMT) welding, respectively. The microstructure near the interface of Ti and steel is then examined using SEM, EBSD, EDS, with emphasis on the ICs in terms of chemical elements and morphologies. Results show that FeTi and Fe
Ti are the main ICs near the interface, and responsible for the failure of the welds. The effect of welding heat input on the formation of ICs is investigated as well. Results show that ICs are smaller when the heat input is low. Under low heat input circumstance, the tensile strength of the weld can reach up to 420 MPa.
Excessive sympathetic activity contributes to the pathogenesis of hypertension and the progression of the related organ damage. Adipose afferent reflex (AAR) is a sympatho‐excitatory reflex that the ...afferent activity from white adipose tissue (WAT) increases sympathetic outflow and blood pressure. Hypothalamic paraventricular nucleus (PVN or PVH) is one of the central sites in the control of the AAR, and ionotropic glutamate receptors in the nucleus mediate the AAR. The AAR is enhanced in obesity and obesity hypertension. Enhanced WAT afferent activity and AAR contribute to the excessive sympathetic activation and hypertension in obesity. Blockage of the AAR attenuates the excessive sympathetic activity and hypertension. Leptin may be one of sensors in the WAT for the AAR, and is involved in the enhanced AAR in obesity and hypertension. This review focuses on the neuroanatomical basis and physiological functions of the AAR, and the important role of the enhanced AAR in the pathogenesis of obesity hypertension.
Persistent excessive sympathetic activation greatly contributes to the pathogenesis of chronic heart failure (CHF) and hypertension. Cardiac sympathetic afferent reflex (CSAR) is a sympathoexcitatory ...reflex with positive feedback characteristics. Humoral factors such as bradykinin, adenosine and reactive oxygen species produced in myocardium due to myocardial ischaemia stimulate cardiac sympathetic afferents and thereby reflexly increase sympathetic activity and blood pressure. The CSAR is enhanced in myocardial ischaemia, CHF and hypertension. The enhanced CSAR at least partially contributes to the sympathetic activation and pathogenesis of these diseases. Nucleus of the solitary tract (NTS), hypothalamic paraventricular nucleus (PVN) and rostral ventrolateral medulla are the most important central sites involved in the modulation and integration of the CSAR. Angiotensin II, AT1 receptors and NAD(P)H oxidase‐derived superoxide anions pathway in the PVN are mainly responsible for the enhanced CSAR in CHF and hypertension. Central angiotensin‐(1‐7), nitric oxide, endothelin, intermedin, hydrogen peroxide and several other signal molecules are involved in regulating CSAR. Blockade of the CSAR shows beneficial effects in CHF and hypertension. This review focuses on the anatomical and physiological basis of the CSAR, the interaction of CSAR with baroreflex and chemoreflex, and the role of enhanced CSAR in the pathogenesis of CHF and hypertension.
The event rate, energy distribution and time-domain behaviour of repeating fast radio bursts (FRBs) contain essential information regarding their physical nature and central engine, which are as yet ...unknown
. As the first precisely localized source, FRB 121102 (refs.
) has been extensively observed and shows non-Poisson clustering of bursts over time and a power-law energy distribution
. However, the extent of the energy distribution towards the fainter end was not known. Here we report the detection of 1,652 independent bursts with a peak burst rate of 122 h
, in 59.5 hours spanning 47 days. A peak in the isotropic equivalent energy distribution is found to be approximately 4.8 × 10
erg at 1.25 GHz, below which the detection of bursts is suppressed. The burst energy distribution is bimodal, and well characterized by a combination of a log-normal function and a generalized Cauchy function. The large number of bursts in hour-long spans allows sensitive periodicity searches between 1 ms and 1,000 s. The non-detection of any periodicity or quasi-periodicity poses challenges for models involving a single rotating compact object. The high burst rate also implies that FRBs must be generated with a high radiative efficiency, disfavouring emission mechanisms with large energy requirements or contrived triggering conditions.
Abstract
Identifying how energy transfer proceeds from macroscales down to microscales in collisionless plasmas is at the forefront of astrophysics and space physics. It provides information on the ...evolution of involved plasma systems and the generation of high-energy particles in the universe. Here we report two cross-scale energy-transfer events observed by NASA’s Magnetospheric Multiscale spacecraft in Earth’s magnetosphere. In these events, hot ions simultaneously undergo interactions with macroscale (~
$${10}^{5}$$
10
5
km) ultra-low-frequency waves and microscale (
$$\sim {10}^{3}$$
~
10
3
km) electromagnetic-ion-cyclotron (EMIC) waves. The cross-scale interactions cause energy to directly transfer from macroscales to microscales, and finally dissipate at microscales via EMIC-wave-induced ion energization. The direct measurements of the energy transfer rate in the second event confirm the efficiency of this cross-scale transfer process, whose timescale is estimated to be roughly ten EMIC-wave periods about (1 min). Therefore, these observations experimentally demonstrate that simultaneous macroscale and microscale wave-ion interactions provide an efficient mechanism for cross-scale energy transfer and plasma energization in astrophysical and space plasmas.
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Anion exchange membranes (AEMs) are a crucial constituent for alkaline fuel cells. As the core component of fuel cells, the low performance AEMs restrict the development and ...application of the fuel cells. Herein, the trade-off between the OH– conductivity and dimensional stability was solved by constructing AEMs with adequate OH– conductivity and satisfactory alkali resistance using Tröger’s base (TB) poly (crown ether)s (PCEs) as the main chain, the embedded quaternary ammonium (QA) and Na+-functionalized crown ether units as the cationic group. Crown ether is an electron donator, and can capture Na+ to form Na+-functionalized crown ether units to conveniently transfer OH– and significantly promote the alkaline stability of the AEMs. The influence of the Na+-functionalized crown ether units on the performance of AEMs was studied in detail. The PCEs based AEMs show an obvious hydrophobic-hydrophilic microphase separation. These features make them ideal platforms for the OH– conduction applications. As expected, the as-prepared PCEs-QA-100% (100% is the degree of cross-linking) AEM with an ionic exchange capacity (IEC) of 2.07 meq g−1 has a high OH– conductivity of 159 mS cm−1 at 80 °C. Furthermore, the membrane electrode assemblies fabricated using the PCEs-QA-100% AEM possess a maximum power density of 291 mW cm−2 under the current density of 500 mA cm−2.
Treatment with 0.5 mM salicylic acid (SA) significantly alleviated growth inhibition induced by drought in wheat seedlings, manifested by less decreassed fresh mass, dry mass, plant height, root ...length, and less increased lipid peroxidation. Under drought stress, SA significantly increased the content of ascorbate (ASA) and glutathione (GSH). We determined the full-length cDNA sequences of genes encoding the glutathione-S-transferase 1 (GST1) and 2 (GST2) and we also measured the transcription of eight genes related to ASA-GSH cycle. The results indicated that exogenous SA significantly enhanced the transcription of GST1, GST2, glutathione reductase (GR), and monodehydroascorbate reductase (MDHAR) genes during almost the entire drought period, but only increased those of dehydroascorbate reductase (DHAR) at 12 h, glutathione peroxidase (GPX1) at 48 h, phospholipid hydroperoxide glutathione peroxidase (GPX2) at 12 and 24 h, and glutathione synthetase (GSHS) at 12, 24, and 48 h. This implies that SA alleviates the detrimental effects of drought stress on wheat seedling growth by influencing the ASA-GSH cycle.
•HE behavior of localized zones in SUS301L-MT stainless steel was investigated using SSRT tests during in situ electrochemical hydrogen charging.•HE cracks in BM and HAZ specimens initiated along ...αˊ/γ interface near the specimen edge.•HE cracks in WM specimen initiated along the δ-ferrites distributed at austenitic grain boundaries.•HE cracks propagated in BM, HAZ and WM exhibited hydrogen enhanced local plastic deformation and hydrogen induced decohesion mechanisms controlled by the hydrogen diffusion behavior in the front of cracks tips.
Hydrogen induced stress corrosion cracking behavior of SUS301L-MT laser-arc hybrid welded (LAHW) joints has been investigated in our previous works. However, the hydrogen embrittlement (HE) behavior in each zone of this joint is still unclear. In this work, in combination with microstructures, cracks propagation paths and fracture surface morphologies analysis, in situ electrochemical hydrogen charging during slow strain rate tensile (SSRT) tests were performed on the specimens cut from base metal (BM), heat-affected zone (HAZ) and weld metal (WM) in SUS301L-MT stainless steel LAHW joints to investigate the HE behavior of each zone. The results indicated that deformation induced martensite transformation occurred in BM and HAZ specimens during SSRT tests, resulted in cleavage morphologies on the fracture center and dimples on other areas. The fracture surface of WM specimen was all covered with dimples. During in situ hydrogen charging, the cracks in BM and HAZ specimens initiated along αˊ/γ interface near the specimen edge. The cracks in WM specimen initiated along the δ-ferrites distributed at austenitic grain boundaries. After the cracks initiated, the hydrogen concentration distribution in combination with stress field at the front of cracks tips would induce the cracks propagation by “hydrogen enhanced local plastic deformation” and “hydrogen enhanced decohesion” mechanisms. As a result, mainly fracture characterizations of intergranular cracking, transgranular cleavage and secondary cracks formed on the fracture surface.
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