Impact of air‐handling system exhaust failure on dissemination pattern of simulant pathogen particles in a clinical biocontainment unit

Biocontainment units (BCUs) are facilities used to care for patients with highly infectious diseases. However, there is limited guidance on BCU protocols and design. This study presents the first investigation of how HVAC (heating, ventilation, air‐conditioning) operating conditions influence the dissemination of fluorescent tracer particles released in a BCU. Test conditions included normal HVAC operation and exhaust failure resulting in loss of negative pressure. A suspension of optical brightener powder and water was nebulized to produce fluorescent particles simulating droplet nuclei (0.5‐5 μm). Airborne particle number concentrations were monitored by Instantaneous Biological Analyzers and Collectors (FLIR Systems). During normal HVAC operation, fluorescent tracer particles were contained in the isolation room (average concentration = 1 × 10⁴ ± 3 × 10³/L_air). Under exhaust failure, the automated HVAC system maximizes airflow into areas adjacent to isolation rooms to attempt to maintain negative pressure differential. However, 6% of the fluorescent particles were transported through cracks around doors/door handles out of the isolation room via airflow alone and not by movement of personnel or doors. Overall, this study provides a systematic method for evaluating capabilities to contain aerosolized particles during various HVAC scenarios. Recommendations are provided to improve situation‐specific BCU safety.     

Adsorption of Uranium from Dilute Aqueous Solution on Inorganic Adsorbents

Abstract

The adsorption of uranium from a dilute aqueous solution by a large number of inorganic adsorbents has been investigated. A mixture of aluminum hydroxide, ferric hydroxide, and activated carbon in the weight ratio 1:3:4 has shown a high adsorbability for uranium. The separation of uranium from a dilute aqueous solution by this mixed adsorbent under various temperatures and pH values has been studied. The adsorbability was found to exhibit a maximum at pH 4.0 to 5.5 and to decrease with increasing temperature. A number of eluting solutions for the desorption of uranium from the mixed adsorbent were also tested; 1 N (NH₄)₂ CO ₃ was found to be the most suitable eluting solution (93% recovery of uranium).     

Process optimisation and physicochemical characterisation of enzymatic hydrolysates of proteins from co‐products of Atlantic Salmon (Salmo salar) and Yellowtail Kingfish (Seriola lalandi)

The aim of this study was to develop an enzymatic hydrolysis process of protein co‐products for two major commercial fish species in Australia: Atlantic salmon (AS) and Yellowtail kingfish (YTK). The outcomes are to produce high protein recovery of fish protein hydrolysates within controlled molecular weight ranges that display enhanced physicochemical properties of oil binding and emulsification. Three enzymes (Flavourzyme, Neutrase and Alcalase) were applied to processing co‐products. Protein recovery and physicochemical properties were evaluated with increasing hydrolysis time from 30 min to 180 min and ratio of enzyme to substrate (E/S) from 0.5% to 3.0%. In order to achieve a product with optimum emulsifying capacity (50 ± 0.6 m² g^?1), an E/S ratio of 0.6–1.3% Flavourzyme was applied for 30–111 min with a protein recovery of 55%; in order to achieve a product with optimum oil‐binding capacity (8.3 ± 0.3 g oil g hydrolysates^?1), an E/S ratio of 2.3–3.0% Flavourzyme was applied for 25–64 min with a protein recovery of 70%. YTK protein hydrolysates were further membrane‐fractionated into five fractions (>100 kDa, 50–100 kDa, 30–50 kDa, 10–30 kDa and <10 kDa), and of these, the 10–30 kDa exhibited the best properties of oil binding (19 ± 0.3 g oil g hydrolysates^?1) and emulsification (57 ± 0.7 m² g^?1). These results demonstrate the importance of enzymatic hydrolysis of seafood co‐products into high‐value ingredients for food products and processing.     

高含油高乳化洗罐废水处理工程实例

某石化公司洗罐废水具有油含量高、COD高、乳化严重的特点,采用溶气气浮+电极气浮+微电解氧化工艺处理后,油和COD去除率均达到90%以上。该工艺装置采用一体化撬装方式,施工方便。该组合工艺运行稳定,处理效果好,吨水运行处理成本仅3.83元,装置出水保证了下游生化处理单元不受冲击。     

Combustion enhancement and inhibition of hydrogen-doped methane flame by HFC-227ea

Hydrogen enriched with compressed natural gas is an efficient and environment-friendly gaseous fuel. However, the safety issues of mixture and the method to control or weaken their combustion are highly concerned. To explore the inhibition effect of halogenated fire suppressants on the mixture, the effect of HFC-227ea on the laminar premixed methane/air flames, with different fractions of H₂, have been studied. Burning velocities have been measured with constant-volume combustion chamber and kinetically modelled a recently assembled kinetic mechanism. The fractions of H₂ influence the enhancement and inhibition effect of HFC-227ea, and it is less effective with the lean mixture. In stoichiometric condition, HFC-227ea showed good inhibition effect on the mixture flames. The HFC-227ea increased the burning velocities of CH₄-0% H₂-air and CH₄-10% H₂-air flames at leanest condition, whereas the increased burning velocity arising from HFC-227ea not occurred as the addition of H₂ above 20%. Experimental results coincided well with numerical results, however the agreement was poor for the leanest flames at low agent loading. Lastly, kinetic mechanism analysis was used to interpret the combustion enhancement and inhibition effect of hydrogen-doped methane flame by HFC-227ea.     

Approximate solution for a variable-coefficient semilinear heat equation with nonlocal boundary conditions

This paper develops an iterative algorithm for the solution to a variable-coefficient semilinear heat equation with nonlocal boundary conditions in the reproducing space. It is proved that the approximate sequence u _n (x, t) converges to the exact solution u(x, t). Moreover, the partial derivatives of u _n (x, t) are also convergent to the partial derivatives of u(x, t). And the approximate sequence u _n (x, t) is the best approximation under a complete normal orthogonal system.     

南京钢铁30000m~3/h空分设备项目进度控制方法

简介影响30000 m3/h空分设备项目进度控制的主要问题,介绍为实现项目进度的控制目标,而采取的优化项目组织形式、完善项目计划管理措施、引入项目考核机制和加强项目团队建设等具体措施。     

28000m~3/h空分装置开车总结

内蒙古鄂尔多斯市乌审旗世林化工有限责任公司30万t/a甲醇项目配置了28 000 m3/h空分装置。介绍了空分装置的工艺流程;指出了装置设计与安装阶段不尽合理之处;采取了相关的完善措施;提出了装置试车的操作要点。结果表明:空分装置一次试车成功,产出了纯度大于99.6%的合成氧气和纯度大于99.999%的合格氮气。     

在线传感器网络智能预知维修诊断技术在空压机组上的运用

为解决企业传统设备管理中离线点巡检存在的问题,结合在线传感器网络的优点,以空压机组为实例,提出了一种在线智能预知维修诊断控制策略,进一步做好企业设备的运行管理工作。