Summary
Background
Transient elastography is a non‐invasive method for staging liver fibrosis. The meta‐analysis using the hierarchical models to evaluate the diagnostic accuracy of transient ...elastography for the staging of liver fibrosis in patients with chronic hepatitis B was rarely reported.
Aim
A meta‐analysis using the hierarchical models was performed to assess transient elastography for diagnosing and stage liver fibrosis in patients with chronic hepatitis B.
Methods
Electronic databases were searched and studies were identified to assess the diagnostic accuracy of transient elastography in CHB patients for staging fibrosis F ≥ 2, F ≥ 3 and F = 4 with liver biopsy as a reference standard. The hierarchical summary receiver operating characteristic curve and the bivariate models were performed to evaluate the diagnostic accuracy of transient elastography, and meta‐regression analyses were performed to explore the heterogeneity. The quality Assessment of Diagnostic Accuracy Studies‐2 tool was used to assess the quality of studies.
Results
Twenty‐seven studies with a total of 4386 patients were included in the meta‐analysis. The summary sensitivity of transient elastography for staging fibrosis F ≥ 2, F ≥ 3 and F = 4 was 0.806 (95% CI, 0.756–0.847), 0.819 (95% CI, 0.748–0.874) and 0.863 (95% CI, 0.818–0.898), respectively, and the summary specificity was 0.824 (95% CI, 0.761–0.873), 0.866 (95% CI, 0.824–0.899) and 0.875 (95% CI, 0.840–0.903), respectively. The corresponding area under the summary receiver operating characteristic curve was 0.88 (95% CI, 0.85–0.91), 0.91 (95% CI, 0.88–0.93) and 0.93 (95% CI, 0.91–0.95), respectively. Meta‐regression showed that patient age contributed to heterogeneity.
Conclusions
Transient elastography performs well to diagnose liver fibrosis in patients with chronic hepatitis B, which may reduce the use of liver biopsy.
Sorption thermal storage for solar energy Yu, N.; Wang, R.Z.; Wang, L.W.
Progress in energy and combustion science,
10/2013, Letnik:
39, Številka:
5
Journal Article
Recenzirano
Sorption technologies, which are considered mainly for solar cooling and heat pumping before, have gained a lot of interests for heat storage of solar energy in recent years, due to their high energy ...densities and long-term preservation ability for thermal energy. The aim of this review is to provide an insight into the basic knowledge and the current state of the art of research on sorption thermal storage technologies. The first section is concerned with the terminology and classification for sorption processes to give a clear scope of discussion in this paper. Sorption thermal storage is suggested to cover four technologies: liquid absorption, solid adsorption, chemical reaction and composite materials. Then the storage mechanisms and descriptions of basic closed and open cycles are given. The progress of sorption materials, cycles, and systems are also reviewed. Besides the well-known sorbents like silica gels and zeolites, some new materials, including aluminophosphates (AlPOs), silico-aluminophosphates (SAPOs) and metal-organic frameworks (MOFs), are proposed for heat storage. As energy density is a key criterion, emphais is given to the comparison of storage densities and charging tempertures for different materials. Ongoing research and development studies show that the challenges of the technology focus on the aspects of different types of sorption materials, the configurations of absorption cycles and advanced adsorption reactors. Booming progress illustrates that sorption thermal storage is a realistic and sustainable option for storing solar energy, especially for long-term applications. To bring the sorption storage solution into market, more intensive studies in fields of evaluation of advanced materials and development of efficient and compact prototypes are still required.
The mechanism of superconductivity in cuprates remains one of the big challenges of condensed matter physics. High-Tc
cuprates crystallize into a layered perovskite structure featuring copper oxygen ...octahedral coordination. Due to the Jahn Teller effect in combination with the strong static Coulomb interaction, the octahedra in high-Tc
cuprates are elongated along the c axis, leading to a 3dx²-y² orbital at the top of the band structure wherein the doped holes reside. This scenario gives rise to 2D characteristics in high-Tc
cuprates that favor d-wave pairing symmetry. Here, we report superconductivity in a cuprate Ba₂CuO4-y, wherein the local octahedron is in a very exceptional compressed version. The Ba₂CuO4-y compound was synthesized at high pressure at high temperatures and shows bulk superconductivity with critical temperature (Tc
) above 70 K at ambient conditions. This superconducting transition temperature is more than 30 K higher than the Tc
for the isostructural counterparts based on classical La₂CuO₄. X-ray absorption measurements indicate the heavily doped nature of the Ba₂CuO4-y superconductor. In compressed octahedron, the 3d3z²-r² orbital will be lifted above the 3dx²-y² orbital, leading to significant 3D nature in addition to the conventional 3dx²-y² orbital. This work sheds important light on advancing our comprehensive understanding of the superconducting mechanism of high Tc
in cuprate materials.
Abstract
We present the second release of value-added catalogues of the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC DR2). The catalogues present values of radial velocity Vr, ...atmospheric parameters – effective temperature Teff, surface gravity log g, metallicity Fe/H, α-element to iron (metal) abundance ratio α/Fe (α/M), elemental abundances C/H and N/H and absolute magnitudes MV and $M_{K_{\rm s}}$ deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC since 2011 September until 2014 June. The catalogues also give values of interstellar reddening, distance and orbital parameters determined with a variety of techniques, as well as proper motions and multiband photometry from the far-UV to the mid-IR collected from the literature and various surveys. Accuracies of radial velocities reach 5 km s−1 for the late-type stars, and those of distance estimates range between 10 and 30 per cent, depending on the spectral signal-to-noise ratios. Precisions of Fe/H, C/H and N/H estimates reach 0.1 dex, and those of α/Fe and α/M reach 0.05 dex. The large number of stars, the contiguous sky coverage, the simple yet non-trivial target selection function and the robust estimates of stellar radial velocities and atmospheric parameters, distances and elemental abundances make the catalogues a valuable data set to study the structure and evolution of the Galaxy, especially the solar-neighbourhood and the outer disc.
To explore the characteristics of Helicobacter pylori resistance in China and the association between antibiotic resistance and several clinical factors.
H. pylori strains were collected from ...patients in 13 provinces or cities in China between 2010 and 2016. Demographic data including type of disease, geographic area, age, gender and isolation year were collected to analyse their association with antibiotic resistance. Antibiotic resistance was detected using the Etest test and the Kirby-Bauer disc diffusion method.
H. pylori were successfully cultured from 1117 patients. The prevalence of metronidazole, clarithromycin (CLA), azithromycin, levofloxacin (LEV), moxifloxacin, amoxicillin (AMO), tetracycline and rifampicin resistance was 78.2, 22.1, 23.3, 19.2, 17.2, 3.4, 1.9 and 1.5%, respectively. No resistance to furazolidone was observed. The resistance rates to LEV and moxifloxacin were higher in strains isolated from patients with gastritis compared to those with duodenal ulcer and among women. Compared to patients ≥40 years old, younger patients exhibited lower resistance rates to CLA, azithromycin, LEV and moxifloxacin. The resistance rates to CLA and AMO were higher in strains isolated more recently, and we also found that the prevalence of resistance to metronidazole, CLA, azithromycin and AMO were significantly different among different regions of China.
The resistance rates to metronidazole, CLA and LEV were high in China. Patient age, gender, disease and location were associated with the resistance of H. pylori to some antibiotics. Furazolidone, AMO and tetracycline are better choices for H. pylori treatment in China.
In this forward-looking perspective, the current technologies for low-temperature waste heat recovery are first analyzed from two aspects: (i) the local waste heat recovery technology and (ii) global ...optimization of energy flow network. Based on the analysis, barriers for the further promotion of waste heat recovery are outlined, and they include the lack of global optimization methodology, distributed waste heat recovery system with high costs, and mismatches between waste heat source and demand. To address these issues, perspectives on three aspects are provided. First, advanced graphical analysis and optimization methodology integrating the heat exchange and energy conversion can promote the user-friendly optimization. Second, concentrated waste heat recovery and supply can save the investment, installation area and operation costs, thereby making the waste heat recovery cost-effective. Third, thermal storage, thermal transportation and high temperature heat pump can better couple the waste heat source and user demand from time-scale, spatial scale and energy grade, respectively. Visions for the future are combined with technical details to provide comprehensive perspectives for the next-step waste heat recovery.
•Technologies for low-temperature waste heat recovery are analyzed.•Optimizing method for combined heat exchange and conversion network is discussed.•Concentrated waste heat recovery and supply is a cost-saving option.•Technologies for the waste heat source and user demand coupling are discussed.
In this paper, the principles underlying the operation of desiccant cooling systems are recalled and their actual technological applications are discussed. Through a literature review, the ...feasibility of the desiccant cooling in different climates is proven and the advantages it can offer in terms energy and cost savings are underscored. Some commented examples are presented to illustrate how the desiccant cooling can be a perfective supplement to other cooling systems such as traditional vapour compression air conditioning system, the evaporative cooling, and the chilled-ceiling radiant cooling. It is notably shown that the desiccant materials, when associated with evaporative cooling or chilled-ceiling radiant cooling, can render them applicable under a diversity of climatic conditions.
SDC (Solid desiccant cooling) systems have gained increasing interest as an alternative air conditioning technology. Performance of desiccant plays a crucial role in overall performance of the whole ...system, especially in terms of dehumidification and regeneration capacity. It is desirable to explore desiccant possessing high adsorption capacity and good regeneration ability. Thus, this review summarizes recent researches and developments on novel solid desiccant materials that can be adopted in SDC systems. The materials include composite desiccants, nanoporous inorganic materials and polymeric desiccants. Adsorption isotherms are concluded and compared. Regeneration ability is also considered for full use of low grade thermal energy. Results show that by proper selection of host matrix and immersed salts, composite desiccants have improved capacity of dehumidification and regeneration. Besides, a good balance can be reached between regeneration and adsorption capacity by tailoring textural properties of nanoporous inorganic materials. For polymeric desiccants, especially MIL type (materials of Institute Lavoisier Frameworks), further progress in adsorptive dehumidification will be anticipated. Though some novel materials approach requirements for SDC systems, no material currently available can perfectly satisfy all the required demands. In this case, more intensive researches in the field of development and evaluation of advanced materials are still required.
•Recent progress on desiccants for solid desiccant cooling systems is reviewed.•Desiccants include composite, nanoporous inorganic and polymeric materials.•Adsorption isotherms of these materials are concluded and compared.•Regeneration ability is considered for full use of low grade thermal energy.
NZEB (Net zero energy building) is regarded as an integrated solution to address problems of energy-saving, environmental protection, and CO2 emission reduction in the building section. NZEB could be ...even possible with electricity production if enough renewable energy could be used. Moreover, various building-service systems with renewable energy sources have been widely considered for potential applications in NZEB. All of these new features extend the technical boundary of the conventional energy-efficient buildings, attach a more profound implication to the sustainable development of building technology, and therefore pose a challenge to evaluation works on NZEB performance.
This paper presents a guided tour on NZEB evaluation through literature-research. An overview about definitions and energy-efficient measures of NZEB is presented so that the research object and technology boundary can be clarified for NZEB evaluation. Then, a summary of widely-used research method, tool and performance indicator in evaluation is provided for the methodology part. This part also includes a discussion on the application of LCA (life cycle assessment) in NZEB evaluation and LCA's role in promoting a well-defined NZEB. Finally, potential progress in NZEB evaluation with possible development trends is highlighted in terms of energy storage, load match and smart grid.
•Definitions and typical energy-efficient measures of net zero energy building are reviewed.•Research methods, tools and performance indicators for evaluation methodology are summarized.•Possible development trends of net zero energy building are discussed.
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