Cytotoxic Triosmium Carbonyl Clusters: A Structure–Activity Relationship Study

A structure–activity relationship (SAR) study of the triosmium carbonyl cluster Os₃(CO)₁₀(NCCH₃)₂ was carried out with a series of clusters of the general formula Os₃(CO)_12?nL_n, cationic osmium clusters and a hemi‐labile maltolato‐Os cluster. The SAR results showed that good solubility in DMSO and at least one vacant site are required for cytotoxicity. In vitro evaluation of these new compounds showed that some are selectively active against estrogen receptor (ER)‐independent MDA‐MB‐231 breast cancer cell lines relative to ER‐dependent MCF‐7 breast cancer cells, suggesting that the compounds have a different biological target specific to MDA‐MB‐231 cells. In particular, the maltolato cluster exhibits strong antiproliferative activity, with an IC₅₀ value of 3 μM after only 24 h incubation. Additionally, biochemical assays conducted with the cationic cluster show that it induces apoptosis, although a biological target has not yet been identified. Further research to establish the molecular targets of these compounds and to develop improved organometallic clusters as potential breast cancer therapeutics is underway.     

Crystallization of Bismuth Borosilicate-Based Dielectric Thick Films on a LiZn Ferrite Substrate

The compatibility and crystallization of dielectric thick films, consisting of a bismuth borosilicate glass and crystalline cordierite, on a LiZn ferrite substrate were investigated by focusing on phase development and microstructural changes. Significant diffusion of Li and Fe from the substrate to the dielectric was confirmed as unexpected crystalline phases such as Li₂Al₂Si₃O₁₀ and Fe₂O₃ were found in the thick films fired at 850°C. The crystallization was believed to be initiated from the film interface and developed further toward the film surface as evidenced from cross-sectional microstructures of the films with additional firings. The degree of crystallization and the relative contents of the observed phases were dependent on the ratio between the glass and cordierite and the number of refirings.     

Zr－Nb系合金耐蚀性能研究

结合核动力堆用燃料包壳对锆合金耐蚀性能的要求，大范围考察了Ｎｂ含量为０．５％，１．０％，２．６％（ｗｔ％）的Ｚｒ—Ｎｂ二元合金及含Ｃｒ、Ｍｏ、Ｓｎ、Ｂｉ、Ｆｅ、Ｃｅ和Ｓｉ的Ｚｒ－１Ｎｂ及多元合金，共１７种成分的Ｚｒ－Ｎｂ系合金在４００℃，１０．３ＭＰａ水蒸汽中的长期腐蚀规律（达１８２天）。在腐蚀转折前，Ｚｒ－Ｎｂ系合金的腐蚀动力学曲线均近似于抛物线规律，而在转折之后存在与线性规律偏离现象。长期腐蚀增重的分析说明：通过合理的多元合金化，即增加或降低Ｎｂ含量，并主加Ｆｅ、Ｂｉ、Ｓｎ和Ｎｉ而辅加少量的Ｃｒ、Ｍｏ、Ｔｅ和Ｓｉ，Ｚｒ－１Ｎｂ合金的耐蚀性大有潜力可挖。     

Interface characterization of Al/Cu 2-ply composites under various loading conditions

The effects of reduction ratio during roll bonding on the microstructural evolution at interface and subsequent mechanical properties of roll-bonded Al/Cu 2-ply sheets were investigated. The interface microstructures for several Al/Cu 2-ply sheets fabricated under different reduction ratios between 30% and 65% were verified by transmission electron microscopy (TEM). Taking the difference of interface microstructure into consideration, 3-point bending and peel tests were performed for obtaining flexural and bonding strengths for Al/Cu 2-ply sheets. The effect of the quantified areas of metallurgical bonding at interfaces on the bonding strength was also discussed. The results show that both the bonding and flexural strengths for Al/Cu 2-ply sheets are reduced by decreasing the reduction ratio during the roll bonding process, which is strongly correlated with the interface microstructure. This was especially verified by observing the interface delamination from the 3-point bent samples.     

SARS-CoV-2 Spike Protein and Mouse Coronavirus Inhibit Biofilm Formation by Streptococcus pneumoniae and Staphylococcus aureus

The presence of co-infections or superinfections with bacterial pathogens in COVID-19 patients is associated with poor outcomes, including increased morbidity and mortality. We hypothesized that SARS-CoV-2 and its components interact with the biofilms generated by commensal bacteria, which may contribute to co-infections. This study employed crystal violet staining and particle-tracking microrheology to characterize the formation of biofilms by Streptococcus pneumoniae and Staphylococcus aureus that commonly cause secondary bacterial pneumonia. Microrheology analyses suggested that these biofilms were inhomogeneous soft solids, consistent with their dynamic characteristics. Biofilm formation by both bacteria was significantly inhibited by co-incubation with recombinant SARS-CoV-2 spike S1 subunit and both S1 + S2 subunits, but not with S2 extracellular domain nor nucleocapsid protein. Addition of spike S1 and S2 antibodies to spike protein could partially restore bacterial biofilm production. Furthermore, biofilm formation in vitro was also compromised by live murine hepatitis virus, a related beta-coronavirus. Supporting data from LC-MS-based proteomics of spike–biofilm interactions revealed differential expression of proteins involved in quorum sensing and biofilm maturation, such as the AI-2E family transporter and LuxS, a key enzyme for AI-2 biosynthesis. Our findings suggest that these opportunistic pathogens may egress from biofilms to resume a more virulent planktonic lifestyle during coronavirus infections. The dispersion of pathogens from biofilms may culminate in potentially severe secondary infections with poor prognosis. Further detailed investigations are warranted to establish bacterial biofilms as risk factors for secondary pneumonia in COVID-19 patients.     

Optimized centre-feed clarifier design for the Tai Po Sewage Treatment Works,Hong Kong

Stability of sludge blanket is a critical factor controlling the performance of clarifiers. A three-dimensional computational fluid dynamics (CFD) model was applied to optimize the clarifier design at the Tai Po Sewage Treatment Works, Hong Kong. Validated by field data, the CFD model evaluated the key clarifier design elements including side-water depth, centre-feed inlet, flocculation well and returned activated sludge (RAS) flow. Based on field observations and modelling results, the new design aims at eliminating the strong turbulence typical of centre-feed inlets in the clarifier, thus creating a better flocculation environment, and reducing disturbance to the sludge blanket. The modelling results also demonstrated a marked improvement in clarifier performance after the increase in clarifier depth and hence sludge storage capacity. The increased storage capacity reduces the risk of high sludge blanket levels upsetting the clarified effluent quality under high flow or solids loading conditions.     

一个行业就有一种创新

你眼中的中国元素是什么?中国文化历史悠久,对于民族及生活文化更具有独特的气息。中国元素是被中国人认同的、凝结着中华民族传统文化精神,并体现民族的形象、符号或风俗习惯,保持中国文化象征性,均可被视为"中国元素",包括少数民族、剪纸工艺、12生肖、舞龙舞狮等,我个人最爱的是剪纸。你印象最深的一件运用中国元素创作的作品是什么?在2009年,Qee制作了一只2.5英寸的剪     

A conservative method of wavelet neural network based meta-modeling in constrained approximate optimization

The paper aims at the development of the wavelet neural network (WNN) based conservative meta-model that satisfies the constraint feasibility of approximate optimal solution. The WNN based constraint-feasible meta-model is formulated via exterior penalty method to optimally determine interconnection weights and dilation and translation coefficients in the network. Using Ackley’s path function, the approximation performance of WNN is first tested in comparison with BPN. The proposed approach of constraint feasibility is then verified through a ten-bar planar truss problem. For constrained approximate optimization, the structural design of a composite rotor blade is explored to support the proposed strategies.     

Performance of the smoke extraction system for fires in the Busan–Geoje immersed tunnel

A new partial smoke extraction system for the Busan–Geoje immersed tunnel was investigated experimentally using simulated tunnel fires. The tests were performed in a 1:20-scale model tunnel with a smoke extraction duct between two traffic tubes. The fire corresponded to a 5-MW full-scale fire, based on Froude modeling. Isothermal and thermal experimental models were considered. The performance of the partial smoke extraction system was quantified under natural and longitudinal ventilation conditions. The results showed that the smoke extraction efficiency of the natural ventilation was 30% better than with longitudinal ventilation, because of smoke stratification in the tunnel. Additionally, the efficiency obtained from the thermal model was comparable to that from the isothermal model under both ventilation conditions. The results suggested that the use of a partial smoke extraction system without longitudinal ventilation improved the initial visibility during tunnel fires.