金属多孔材料喷墨制备法的研究与进展

喷墨三维打印作为金属增材制造技术的一种重要方法,已广泛应用于金属多孔材料的制备,具有成本低、操作简单、成型材料范围广、孔结构设计灵活性大,较好的制件精度和结构精细度等优点.系统地总结了钛及钛合金、不锈钢、镍基合金、铝合金等多孔材料喷墨三维打印技术制备工艺与组织结构的国内外最新研究进展、目前存在的问题,以及应用前景.     

Design Method of Inductor-integrated High-power High-frequency Transformers

正This paper presents a design optimization procedure for high-power high-frequency transformer(HFT)used in solid-state transformers(SST).HFTs in DAB dc-dc converters require a specific inductance to lead to a shift in the soft switching region.The inductance,as shown in     

Data quality and uncertainty assessment methodology for pavement LCA

In performing pavement life cycle assessment (LCA), users are facing various reports of energy intensity coefficient (EIC) of pavement materials which differ considerably among data sources and therefore alter the LCA results significantly. Instead of selecting a certain EIC without or of little explanation for the current pavement LCA practices, this study proposed a methodology to build probability density function (PDF) for EIC based on available data-set and their qualities. Each data was first evaluated about the data quality indicator (DQI) through data quality pedigree matrix and converted to PDF in modified Beta distribution form. Three weighting methods, the DQI one, coefficient of variation (COV) one and analytical hierarchy process (AHP) one, were developed to assign weightings for different data. Monte Carlo simulation was run with the weighted PDF of each data as input to obtain the ultimate PDF for EIC. A case study to estimate the bitumen’s EIC with eight data samples were performed using the proposed methodology. It is found (1): the estimates by the proposed methodology is of higher reliability (lower COV) compared to any single data due to utilisation of information of the overall data samples; (2) the AHP weighting method is most favoured despite the results of the three weighting methods are close; (3) the central estimates of bitumen’s EIC are between5.4~5.8 MJ/kg. The proposed methodology is helpful in aiding calculating EICs for pavement materials and capturing uncertainties in LCA results in a statistical sense.     

单一低渗透突出煤层水力冲孔工艺优化应用分析

为了有效提高单一低渗透突出煤层的瓦斯抽采效率，以高压水射流冲击理论为指导，针对平煤股份八矿己组突出煤层特征建立数值模型，模拟分析水力冲孔应力分布规律，通过现场实测分析冲孔有效影响范围，进一步优化设计冲孔参数、指导现场施工。现场应用表明，水力冲孔是一种行之有效的方法，对单一低渗透突出煤层实施水力冲孔卸压增透、提高瓦斯抽采效果具有重要意义。     

Strength Assessment of Welded Joints of High-Strength Alloy Steels by Indentation Method

Strength of Materials - The paper presents the indentation method for strength assessment of the welded joints in high-strength alloy steels, including base metal, heat-affected zone, and welded...     

Revealing key topics shifts in thermal barrier coatings (TBC) as indicators of technological developments for aerospace engines

Scientometrics - Thermal barrier coating (TBC) systems reduce the temperature of the metallic substrate of aerospace engines, resulting in improved component durability, better fuel economy and...     

Expanding the Spectrum of Antibiotics Capable of Killing Multidrug-Resistant Staphylococcus aureus and Pseudomonas aeruginosa

Infections from antibiotic-resistant Staphylococcus aureus and Pseudomonas aeruginosa are a serious threat because reduced antibiotic efficacy complicates treatment decisions and prolongs the disease state in many patients. To expand the arsenal of treatments against antimicrobial-resistant (AMR) pathogens, 600-Da branched polyethylenimine (BPEI) can overcome antibiotic resistance mechanisms and potentiate β-lactam antibiotics against Gram-positive bacteria. BPEI binds cell-wall teichoic acids and disables resistance factors from penicillin binding proteins PBP2a and PBP4. This study describes a new mechanism of action for BPEI potentiation of antibiotics generally regarded as agents effective against Gram-positive pathogens but not Gram-negative bacteria. 600-Da BPEI is able to reduce the barriers to drug influx and facilitate the uptake of a non-β-lactam co-drug, erythromycin, which targets the intracellular machinery. Also, BPEI can suppress production of the cytokine interleukin IL-8 by human epithelial keratinocytes. This enables BPEI to function as a broad-spectrum antibiotic potentiator, and expands the opportunities to improve drug design, antibiotic development, and therapeutic approaches against pathogenic bacteria, especially for wound care.     

生物质电厂废弃物草木灰成分分析及成形

生物质热电厂焚烧废弃物的主要成分是草木灰，其产生量大、密度小。大量草木灰不经处理会造成环境污染问题。本文首先分析草木灰的化学成分，确定草木灰的肥料特征，通过添加NH₄H₂PO₄使草木灰的pH达到国家复合肥的相关标准。选用聚天冬氨酸（30%水溶液）作为复合肥的黏结剂，应用于草木灰复合肥的成形造粒，以增加其抗压强度和肥效。研究不同烘干时间、烘干温度、聚天冬氨酸添加量对草木灰复合肥抗压强度的影响规律，通过分析植物的形态及生理指标，进而研究草木灰复合肥的肥效。结果表明：最佳烘干条件为10h、140℃，聚天冬氨酸对草木灰的抗压强度有明显的增强作用，并且草木灰与聚天冬氨酸的复配比为6g∶1mL时肥效最好。此方法解决了元素循环中断、草木灰环境污染，在运输过程中草木灰复合肥易碎，纯草木灰肥效低等问题。