污水处理中小球藻的自絮凝特性

以BG11(+N)培养基和模拟生活污水为底物,考察了污水处理小球藻(Chlorella vulgaris)的自絮凝特性,探究了自絮凝机理。结果表明:以短沉淀时间运行,小球藻在模拟生活污水中自然形成絮体,沉降性良好;藻细胞表面粗糙,含有丝状、胶状胞外聚合物;絮体内部含有大量短杆菌、球菌;絮体具有相对较高的Na、P、Fe、Ca、Mg元素含量,无机物中主要物质形态为Ca4O(PO4)2。污水处理小球藻的絮凝机理为:基质条件及反应器运行参数等促使藻细胞生理过程发生改变,藻细胞分泌更多絮凝性胞外聚合物增强黏附,生化过程富集P、Fe、Ca、Mg元素改善沉降性,絮凝性细菌大量繁殖促进菌藻共絮凝。     

Antimicrobial and Amyloidogenic Activity of Peptides. Can Antimicrobial Peptides Be Used against SARS-CoV-2?

At present, much attention is paid to the use of antimicrobial peptides (AMPs) of natural and artificial origin to combat pathogens. AMPs have several points that determine their biological activity. We analyzed the structural properties of AMPs, as well as described their mechanism of action and impact on pathogenic bacteria and viruses. Recently published data on the development of new AMP drugs based on a combination of molecular design and genetic engineering approaches are presented. In this article, we have focused on information on the amyloidogenic properties of AMP. This review examines AMP development strategies from the perspective of the current high prevalence of antibiotic-resistant bacteria, and the potential prospects and challenges of using AMPs against infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).     

Differences between oculomotor and perceptual artifacts for temporally limited head mounted displays

We used perceptual and oculomotor measures to understand the negative impacts of low (phantom array) and high (motion blur) duty cycles with a high‐speed, AR‐likehead‐mounted display prototype. We observed large intersubject variability for the detection of phantom array artifacts but a highly consistent and systematic effect on saccadic eye movement targeting during low duty cycle presentations. This adverse effect on saccade endpoints was also related to an increased error rate in a perceptual discrimination task, showing a direct effect of display duty cycle on the perceptual quality. For high duty cycles, the probability of detecting motion blur increased during head movements, and this effect was elevated at lower refresh rates. We did not find an impact of the temporal display characteristics on compensatory eye movements during head motion (e.g., VOR). Together, our results allow us to quantify the tradeoff of different negative spatiotemporal impacts of user movements and make subsequent recommendations for optimized temporal HMD parameters.     

Modification of pool boiling regimes by sand deposition

Sand spots, attached to a copper ball surface by means of polyvinyl acetate adhesive and distributed over the surface with areal density that ranges between one spot per 1.18 cm² (for low‐density spots) and one spot per 0.51 cm² (for high‐density spots), serve as a temporary heat transfer enhancer during the quenching in liquid nitrogen. Highest heat flux densities, achieved during quenching, lie in the range 10.8 to 20.2 W/cm², depending on the sand layer structure. Application of the temporary enhancer increases an amount of heat, evacuated by highly effective nucleate and transition boiling, by factor of 4.5 as compared with the bare sample. The process of sand layer preparation, data acquisition peculiarities, relationship between heat exchange efficiency and the spots areal density, along with sand grit size are discussed in this paper.     

Digital Extraction Column: Measurement and Modeling Techniques

The digitization of extraction columns requires a profound knowledge of the present hydrodynamics/mass transport interaction as well as appropriate measurement techniques for the detection of relevant input and target values. In this article, the different techniques for droplet size distribution as well as concentration determination are presented and new methods for online evaluation are discussed. In combination with the simulation of droplet size, holdup and solute concentration distribution, an online-capable process tool for controlling and optimizing extraction columns will be obtained.     

SBA-15固载磷钨酸催化剂的制备及催化合成叔丁基苯酚

以不同硅烷偶联剂改性的介孔分子筛SBA-15为载体、PW_(12)为催化剂,通过对SBA-15表面共价及非共价修饰制备磷钨酸@介孔分子筛/硅烷偶联剂复合催化剂PW_(12)@SBA-15/YSiX_3(YSiX_3=Apts、Atapts、Papts);并利用FT-IR、XRD、TEM、N_2吸附-脱附对其组成、结构及形貌进行表征。以改性SBA-15分子筛固载磷钨酸催化剂催化合成叔丁基苯酚为研究对象,考察不同硅烷偶联剂、反应温度、苯酚与叔丁醇物质的量比对催化合成叔丁基苯酚的影响,并获得合成叔丁基苯酚的最佳工艺条件,即反应温度145℃、n(苯酚)∶n(叔丁醇)=1∶2.5、重时空速2.2 h~(-1),该最佳反应条件下,PW_(12)@SBA-15/Apts催化剂催化合成叔丁基苯酚的催化活性最高,苯酚转化率为98.3%,2,4-二叔丁基苯酚选择性为57.3%.     

Rapid Discovery of Aspartyl Protease Inhibitors Using an Anchoring Approach

Pharmacophore searches that include anchors, fragments contributing above average to receptor binding, combined with one-step syntheses are a powerful approach for the fast discovery of novel bioactive molecules. Here, we are presenting a pipeline for the rapid and efficient discovery of aspartyl protease inhibitors. First, we hypothesized that hydrazine could be a multi-valent warhead to interact with the active site Asp carboxylic acids. We incorporated the hydrazine anchor in a multicomponent reaction and created a large virtual library of hydrazine derivatives synthetically accessible in one-step. Next, we performed anchor-based pharmacophore screening of the libraries and resynthesized top-ranked compounds. The inhibitory potency of the molecules was finally assessed by an enzyme activity assay and the binding mode confirmed by several soaked crystal structures supporting the validity of the hypothesis and approach. The herein reported pipeline of tools will be of general value for the rapid generation of receptor binders beyond Asp proteases.     

Densification mechanisms and microstructural evolution during spark plasma sintering of boron carbide powders

Micron-sized boron carbide (B₄C) powders were subjected to spark plasma sintering (SPS) under temperature ranging from 1700 °C to 2100 °C for a soaking time of 5, 10 and 20 min and their densification kinetics was determined using a creep deformation model. The densification mechanism was interpreted on the basis of the stress exponent n and the apparent activation energy Q_d from Harrenius plots. Results showed that within the temperature range 1700–2000 °C, creep deformation which was controlled by grain-boundary sliding or by interface reaction contributed to the densification mechanism at low effective stress regime (n = 2,Q_d = 459.36 kJ/mol). While at temperature higher than 2000 °C or at high stress regime, the dominant mechanism appears to be the dislocation climb (n = 6.11).