冷低压分离器油相系统铵盐垢下腐蚀风险的模拟预测

为探究某加氢装置高压换热器管束腐蚀泄漏原因，利用Aspen Plus工艺模拟软件计算了冷低压分离器油相（简称冷低分油）中水质量分数分别为1%,2%,3%时，冷低分油系统的露点温度、氯化铵结晶温度、氯化铵潮解点温度和相对湿度。结果表明：相较于经验的露点温度预测方法，通过引入潮解点、划分系统“湿环境”温度范围判断氯化铵垢下腐蚀风险区域的方法与实际腐蚀案例更为切合；在3种油相含水条件下，换热器管束存在氯化铵垢下腐蚀的“湿环境”温度范围分别为：50~103 ℃,50~161 ℃,50~176 ℃；随着油相中含水量的提高，“湿环境”腐蚀区域逐渐向高温部位迁移，预计铵盐导致的垢下腐蚀将会愈加严重。     

Alterations in the Genomic Distribution of 5hmC in In Vivo Aged Human Skin Fibroblasts

5-Hydroxymethylcytosine (5hmC) is a functionally active epigenetic modification. We analyzed whether changes in DNA 5-hydroxymethylation are an element of age-related epigenetic drift. We tested primary fibroblast cultures originating from individuals aged 22–35 years and 74–94 years. Global quantities of methylation-related DNA modifications were estimated by the dot blot and colorimetric methods. Regions of the genome differentially hydroxymethylated with age (DHMRs) were identified by hMeDIP-seq and the MEDIPS and DiffBind algorithms. Global levels of DNA modifications were not associated with age. We identified numerous DHMRs that were enriched within introns and intergenic regions and most commonly associated with the H3K4me1 histone mark, promoter-flanking regions, and CCCTC-binding factor (CTCF) binding sites. However, only seven DHMRs were identified by both algorithms and all of their settings. Among them, hypo-hydroxymethylated DHMR in the intron of Rab Escort Protein 1 (CHM) coexisted with increased expression in old cells, while increased 5-hydroxymethylation in the bodies of Arginine and Serine Rich Protein 1 (RSRP1) and Mitochondrial Poly(A) Polymerase (MTPAP) did not change their expression. These age-related differences were not associated with changes in the expression of any of the ten-eleven translocation (TET) enzymes or their activity. In conclusion, the distribution of 5hmC in DNA of in vivo aged human fibroblasts underwent age-associated modifications. The identified DHMRs are, likely, marker changes.     

Cold plasma for the disinfection of industrial food-contact surfaces: An overview of current status and opportunities

Food safety is the primary goal for food and drink manufacturers. Cleaning and disinfection practices applied to the processing environment are vital to maintain this safety; yet, current approaches can incur costly downtime and the potential for microorganisms to grow and establish, if not effectively removed. For that reason, manufacturers are seeking nonthermal, online, and continuous disinfection processes to control the microbial levels within the processing environment. One such emerging technique, with great potential, is cold atmospheric pressure plasma (CAP). This review presents the latest advances and challenges associated with CAP-based technologies for the decontamination of surfaces and equipment found within the food-processing environment. It provides a detailed overview of the technology and a comprehensive analysis of the many CAP-based antimicrobial studies on food-contact surfaces and materials. As CAP is considered an emerging technique, many of the recent studies are still in the preliminary stages, with results obtained under widely different conditions. This lack of cohesive information and an inability to directly compare CAP systems has greatly impeded technological development. The review further explores the challenge of scaling CAP technology to meet industry needs, considering aspects such as regulatory constraints, environmental credentials, and cost of use. Finally, a discussion is presented on the future outlook for CAP technology in this area, identifying key challenges that must be addressed to promote industry uptake.     

离线式带钢双面翻转检查站方案设计及实践

针对某酸轧机组检查站穿带困难、检查效率低、产生废品多、故障率高的问题,开发了一种离线式带钢双面检查站。该检查站新增了带钢翻转装置,将在入口分切剪处完成定尺剪切的带钢试样由两侧压板夹紧,中间可升降皮带机落下,翻转装置将带钢试样张紧,并翻转90°或者180°,实现带钢的双面检查。皮带机两侧布置有可升降、可横移的活动操作平台,检测人员站在平台上对带钢进行打磨检查,可同时对带钢上下表面进行检测。由于缩短了带钢的传输距离,有效减少了其他擦划伤的影响,提高了带钢表面质量检测准确性。     

Exploring the Cold-Adaptation Mechanism of Serine Hydroxymethyltransferase by Comparative Molecular Dynamics Simulations

Cold-adapted enzymes feature a lower thermostability and higher catalytic activity compared to their warm-active homologues, which are considered as a consequence of increased flexibility of their molecular structures. The complexity of the (thermo)stability-flexibility-activity relationship makes it difficult to define the strategies and formulate a general theory for enzyme cold adaptation. Here, the psychrophilic serine hydroxymethyltransferase (pSHMT) from Psychromonas ingrahamii and its mesophilic counterpart, mSHMT from Escherichia coli, were subjected to μs-scale multiple-replica molecular dynamics (MD) simulations to explore the cold-adaptation mechanism of the dimeric SHMT. The comparative analyses of MD trajectories reveal that pSHMT exhibits larger structural fluctuations and inter-monomer positional movements, a higher global flexibility, and considerably enhanced local flexibility involving the surface loops and active sites. The largest-amplitude motion mode of pSHMT describes the trends of inter-monomer dissociation and enlargement of the active-site cavity, whereas that of mSHMT characterizes the opposite trends. Based on the comparison of the calculated structural parameters and constructed free energy landscapes (FELs) between the two enzymes, we discuss in-depth the physicochemical principles underlying the stability-flexibility-activity relationships and conclude that (i) pSHMT adopts the global-flexibility mechanism to adapt to the cold environment and, (ii) optimizing the protein-solvent interactions and loosening the inter-monomer association are the main strategies for pSHMT to enhance its flexibility.     

Effect of different control strategies on rapid cold start-up of a 30-cell proton exchange membrane fuel cell stack

Many places experience extreme temperatures below −30 °C, which is a great challenge for the fuel cell vehicle (FCV). The aim of this study is to optimize the strategy to achieve rapid cold start-up of the 30-cell stack at different temperature conditions. The test shows that the stack rapidly starts within 30 s at an ambient temperature of −20 °C. Turning on the coolant at −25 °C show stability of the cell voltage at both ends due to the end-plate heating, however, voltage of intermediate cells fluctuates sharply, and successful start-up is completed after 60 s. The cold start strategy changes to load-voltage cooperative control mode when the ambient temperature reduced to −30 °C, the voltage of multiple cells in the middle of the stack fluctuate more drastic, and start-up takes 113 s. The performance and consistency of the stack did not decay after 20 cold start-up experiments, which indicates that our control strategies effectively avoided irreversible damage to the stack caused by freeze-thaw process.     

Omega-6支撑身体，Omega-3支撑大脑：均衡摄入对儿童大脑发育的影响（网络首发、推荐阅读）

人体大脑和身体的发育，需要从食物中摄取均衡的营养物质。人类大脑是区分人类和其他动物的特征。食物中的必需脂肪酸是机体组织结构和功能的必要组成部分。Omega-6（O6）亚油酸（LA6）是皮肤组织的组成成分，且是炎症、血栓形成、免疫和其他信号分子的前体；Omega-3（O3）α-亚麻酸（ALA3），特别是其长链代谢产物——二十二碳六烯酸（DHA3），是大脑、视网膜和部分神经组织中的关键组分。从富含LA6脂肪酸（缺乏O3脂肪酸）的植物籽中提取出的廉价而优质油脂，是20世纪的西方国家食品工业生产的主要脂肪来源。在代谢通路中，高浓度的LA6脂肪酸可拮抗O3脂肪酸代谢，造成O3脂肪酸不足，因此，在给怀孕动物的饲料中，只提供富含LA6但缺乏O3脂肪酸的油脂作为唯一的脂肪来源，会导致幼崽大脑发育不良。过去20~30年的研究表明，低含量LA6且含DHA3的油脂可改善大脑的功能。近年来的研究较多集中在营养因素对大脑发育的影响，最新研究数据表明，脂肪酸平衡对营养不良儿童的大脑发育尤为重要。世界卫生组织（WHO）越来越重视大脑的营养健康，通过其下属的食品法典委员会，建议用于治疗严重急性营养不良儿童的即食治疗食品中，使用含有均衡脂肪酸组成/构成的脂肪。同样，脂肪酸均衡对老年人可能也很重要。目前，业界已经有了调整油脂成分的方法，以确保脂肪酸均衡，从而维持人体整个生命周期的大脑健康。     

Influences of the inner diameter of the solid shielding tube on the characteristics of the radio-frequency cold atmospheric plasma jet

Active control of the local environment of the cold atmospheric plasma (CAP) jet is of great importance in actual applications since the CAP operates in an open atmosphere with the inevitable entrainment of the surrounding cold air. In this paper, the solid shielding effects of the cylindrical quartz tubes with different inner diameters on the characteristics of the CAP jets driven by a radio-frequency (RF) power supply are studied experimentally. The experimental results show that the total length of the shielded plasma jet can be increased significantly by an appropriate combination of the quartz tube inner diameter and that of the plasma generator nozzle exit with other parameters being unchanged. This phenomenon may be qualitatively attributed to the loss of diffusion of the charged particles in the radial direction under different inner diameters of the quartz tubes. Compared with the plasma free jet, the plasma shielding jet is produced with optimized parameters including longer plasma jet length, higher concentrations of chemically reactive species, higher rotational, vibrational, and electron excitation temperatures when the inner diameters of the solid shielding tube and the generator nozzle exit are the same. A maximum plasma jet length of 52.0 cm is obtained in contrast to that of 5.0 cm of the plasma free jet in this study. The experimental results indicate that the solid shielding effect provides a new method for the active control of the local environment of the RF-CAP jet operating in an open atmosphere.