Cold plasma processing of milk and dairy products

BackgroundThermal pasteurization and sterilization are predominantly used in the dairy industry due to their efficacy in improving the product safety and shelf life. However, heat treatment can cause undesirable protein denaturation, non-enzymatic browning, loss of vitamins and volatile flavor compounds, freezing point depression, and flavour changes. Cold plasma is a non-thermal technology that has gained attention in recent years as a potential alternative method for chemical and thermal disinfection in foods using ambient or moderate temperatures and short treatment times.Scope and approachThis review aims to describe the fundamentals, parameters, and technology on cold plasma, discussing the critical processing factors involved in this technology. Also, it describes the mechanisms of microbial inactivation and provides an overview of the effects of non-thermal plasma on the quality of dairy products, considering a physicochemical, sensory and microbiology perspective.Key findings and conclusionsCold plasma uses less aggressive mechanisms of action to the milk matrix when compared to the techniques currently used, and has shown an excellent performance on the elimination of pathogenic and spoilage microorganisms besides maintaining, in many cases, the nutritional, functional, and sensory characteristics of the product.     

300M超高强钢在中性盐雾环境中的腐蚀行为及机制

摘要：为了研究300M超高强钢在中性盐雾环境中的腐蚀行为及腐蚀机制，采用失重法，宏观、微观腐蚀形貌分析，三维表面轮廓分析及电化学分析的研究方法，来表征腐蚀实验现象并进行分析。结果表明：300M超高强钢在中性盐雾环境中的腐蚀产物为FeOOH、Fe2O3、Fe(OH)3和Fe3O4；腐蚀速率随着腐蚀时间逐渐降低，腐蚀后期（72h）腐蚀速率降低50%；腐蚀初期以点蚀为主，点蚀坑通过横向扩展，逐渐发展为后期的均匀腐蚀，腐蚀表面形貌呈沟壑状；外腐蚀层对基体的保护能力很弱，Cr元素在锈层靠近基体的一侧偏聚使内腐蚀层具有一定的抗腐蚀性。     

Removal and repair techniques for thermal barrier coatings: a review

ABSTRACT

A comprehensive literature review of the existing techniques for removing and repairing of damaged thermal barrier coatings is presented, with the focus on top ceramic coats. The advantages and disadvantages of each technique are compared and assessed. The review shows that there is not a universal method applicable to all coating systems. The selection of the coating removal and repair process must be specific to damaged coating systems, based on their composition, type of damages, and available resources. This review will provide some inside look at various approaches in an effort to meet the different coating repair needs.     

生物质燃气中焦油净化的试验研究

对生物质燃气中焦油的净化进行试验研究,通过在喷淋塔前设置空冷塔的焦油净化系统,并以稻秸秆为原料考察热解温度对生物质燃气中焦油在空冷塔和喷淋塔中的分配情况及化学组成的影响。结果表明,生物质燃气中80%的焦油可在空冷塔中富集,当热解温度由500℃升至750℃时,空冷塔中焦油的占比由84.26%降至80.55%,喷淋塔中焦油占比由15.74%升至19.45%;生物质焦油中超过99%、81%、84%和93%的酚类化合物、烷烯烃、含氮化合物和含氧化合物(除酚类化合物外)在空冷塔中富集,而超过76%的芳烃及其衍生物在喷淋塔中富集。     

Showcase and window to the world: East German architecture abroad 1949–1990

For decades, German Democratic Republic (GDR) architecture was seen as parochial and dictated by the Soviets, yet increasing scholarly interest has generated a picture of debates and specific practices that were embedded in the global process of expansion and crisis of Modernism. Meanwhile, and influenced by the East-West conflict, competing concepts of modernization and national identity arose in the so-called Third World, initiating multifarious cultural transfer processes. This article analyses to what extent the architects from the GDR – a country whose building practice was increasingly shaped by the principles of industrial prefabrication – have played a part in regional contexts and construction methods. It also asks what their role was in international organizations such as Union Internationale des Architects and UNESCO, which promoted their practical engagement abroad. The subject raises issues of possible freedom of action in creative design and fusion processes, but also of bureaucratic constrictions and international relationships ending in unexpected conflicts. The examples outline the field of activities that stretches from pure blueprint delivery for a memorial competition to long-standing work on location when planning whole neighbourhoods. Furthermore, the article examines how the challenges of international planning impacted building culture within the GDR itself.     

多孔道底吹喷枪搅拌的数值模拟与强化机理分析

底吹富氧搅拌是熔池熔炼的一种关键强化技术，对品位低、杂质多的矿产资源具有很好适应性，底吹喷枪是其关键工艺设备。本文将数值模拟与数理统计相结合，建立了多孔道底吹喷枪强化搅拌的三维数学模型，并通过水力学模型实验对数学模型进行了验证。针对模型计算结果，以气泡上升时间、液体的气含率方差和平均湍流强度等为评价标准，对直管及多孔道底吹喷枪搅拌过程的混合均匀度进行对比研究。结果表明：多孔道喷枪喷吹方式在提高熔体搅动能的同时能使中上部熔体的混合更为充分，并在生产实践中取得了良好的应用效果。     

综采工作面粉尘防治问题分析与技术改进

针对新桥煤矿2301综采工作面机载喷雾系统喷雾效果差、喷雾耗水量大造成煤质含水量超标、喷嘴雾化程度不高、喷嘴容易发生堵塞等问题,提出了高压喷雾系统设计方案,选择了1.2mm的锥形引射喷嘴和1.5mm的扇形引射喷嘴。采用固定水泵供水方式,结合工作面实际情况,计算出喷雾总用水量247.5L/min,提高了喷雾射程,提升了除尘效果。     

The cold sintering process: A review on processing features,densification mechanisms and perspectives

Since its first introduction in 2016, cold sintering process (CSP) has gained worldwide interest from the scientific community as green and innovative fabrication route due to the dramatic reduction of processing time, energy, and costs. Cold sintering resembles the geological formation of rocks where a ceramic powder is densified with the aid of a liquid phase under an intense external pressure and limited heating conditions (below 350 °C). Up to date, tens of different materials, including composites, have been successfully processed through CSP and extraordinary results in terms of densification, microstructure and final properties have been achieved. In the present review, processing features and variables, possible densification mechanisms and issues also for the realization of ceramic-based composites are explored. Advantages with respect to existing techniques are analysed and current challenges are described to lay the ground for new processing opportunities to be faced in the near future.     

Pressure-induced transparency of MgO,Al2O3, AlN,and cBN ceramics at room temperature

The in situ axial X-ray diffraction patterns of four ceramic powder samples (MgO, Al₂O₃, AlN, and cBN) that were compressed in a diamond anvil cell under uniaxial non-hydrostatic conditions were recorded. The microscopic deviatoric stress as a function of the pressure was determined from the X-ray diffraction peak broadening analysis: the curves increased approximately linearly with the pressure at the initial compression stage and then levelled off under further compression. Pressure-induced transparency was observed in all of the samples under compression, and the pressure at the turning point on the curves of the microscopic deviatoric stress versus pressure corresponded to the pressure at which the samples became transparent. Analysis of the microstructural features of the pressure-induced transparent samples indicated that the compression caused the grains to fracture, and the broken grains bonded with each other. We demonstrated that the ceramics’ pressure-induced transparency was a process during which the grains were squeezed and broken, the pores were close between the grains, and the broken grains were re-bonded under compression.     

Cold-start performance of an ammonia-fueled spark ignition engine with an on-board fuel reformer

This work demonstrated the first-ever cold-start operation of an ammonia (NH₃)-fueled four-cylinder spark ignition engine with an on-board fuel reformer, applying autothermal reforming. In this system, an electrically heated NH₃-air mixture was provided to a reforming catalyst and approximately 3 s was found to elapse between the start of engine rotation and the onset of combustion. Stable fast idle operation in conjunction with a cold start was realized with a H₂-to-NH₃ molar ratio of 2:1. Nearly zero NH₃ emissions were achieved during cold start and fast idle until the engine warmed up, by adsorbing unburned NH₃ passing through a three-way catalyst before the catalyst was sufficiently warmed up. The NH₃ adsorption capacity of this system could be regenerated during the engine warm-up when the engine was running under lean conditions.