OSHA''s Permissible Exposure Limits: Regulatory Compliance Versus Health Risk

Workplace exposures to airborne chemicals are regulated in the U.S. by the Occupational Safety and Health Administration (OSHA) via the promulgation of permissible exposure limits (PELs). These limits, usually defined as eight-hour time-weighted average values, are enforced as concentrations never to be exceeded. In the case of chronic or delayed toxicants, the PEL is determined from epidemiological evidence and/or quantitative risk assessments based on long-term mean exposures or, equivalently, cumulative lifetime exposures. A statistical model was used to investigate the relation between the compliance strategy, the PEL as a limit never to be exceeded, and the health risk as measured by the probability that an individual's long-term mean exposure concentration is above the PEL. The model incorporates within-worker and between-worker variability in exposure, and assumes the relevant distributions to be log-normal. When data are inadequate to estimate the parameters of the full model, as it is in compliance inspections, it is argued that the probability of a random measurement being above the PEL must be regarded as a lower bound on the probability that a randomly selected worker's long-term mean exposure concentration will exceed the PEL. It is concluded that OSHA's compliance strategy is a reasonable, as well as a practical, means of limiting health risk for chronic or delayed toxicants.     

增加反应物量对化学平衡移动的讨论

本文提出了恒温恒压条件下，在多组分理想气体反应体系中，增加某一反应物的量，化学平衡有可能向反应物方向移动的实例，并引用化学反应进度的概念进行热力讨论．     

碱水驱组分输运过程有效性研究

建立了碱水驱组分孔隙输运数学模型,将模型中所需的物化参数描述为驱油剂浓度相关的函数,用“有效驱替带”量化和分析了吸附、驱油剂段塞尺寸、驱替速度、扩散弥散等因素对碱组分输运过程有效性的影响机理。在此基础上,进一步分析了大庆油田ASP复合驱用碱剂NaOH在孔隙输运过程中的有效性和持久性,并对模拟软件进行了实验验证,它们具有很好的一致性。经过实验验证的模拟软件,不仅可代替部分实验室流动实验和辅助机理分析,而且可以为碱水驱和ASP复合驱工程工艺方案设计和动态监测提供指导。     

Safety of a meningococcal group B vaccine used in response to two university outbreaks

Objective: To assess the safety of meningococcal group B (MenB)-4C vaccine. Participants: Undergraduates, dormitory residents, and persons with high-risk medical conditions received the MenB-4C vaccine two-dose series during mass vaccination clinics from 12/2013 through 11/2014. Methods: Adverse events (AEs) were identified by 15 minutes of observation postvaccination, spontaneous reports, surveys, and hospital surveillance. Causality was assessed for serious adverse events (SAEs). Results: 16,974 persons received 31,313 MenB-4C doses. The incidence of syncope during the 15-minutes post-dose 1 was 0.88/1000 persons. 2% of participants spontaneously reported an AE (most common were arm pain and fever). 3 SAEs were suspected of being caused by the vaccine, including one case of anaphylaxis. Conclusions: Most AEs reported were nonserious and consistent with previous clinical trial findings. Measures to prevent injury from syncope and to treat anaphylaxis should be available wherever vaccines are administered. Our safety evaluation supports the use of MenB-4C in response to outbreaks.     

浅谈化学实验教学的改革与创新

化学课程相对于其他的课程而言,实验部分占据了重要的比例。而实验教学的灵活性,给化学课程的教学又提了新的要求。在化学实验中,针对目前存在的一些问题,应该采取相应的措施进行解决,才能真正实现实验教学的创新与改革发展,给化学实验的发展带去新的局面。     

关于我国化工企业实行绿色管理的思考

近年来 ,世界各国都十分注意经济发展与环境的关系问题。我国已在改革开放的过程中逐步确立了我国经济发展应以可持续发展为中心的战略。化工企业实行绿色管理是我国宏观经济可持续发展的客观要求 ,同时也是我国化工行业的生产和经营的特点所决定的。笔者从我国化工企业的角度出发论证了绿色管理对化工企业生存和发展的重要意义及化工企业实行绿色管理的关键因素 ,并针对我国化工企业的状况提出了可行性建议     

陕北能源化工基地人才需求状况调查与思考

陕北地区是国家21世纪最重要的能源化工基地，但是由于自然条件相对艰苦以及吸引毕业生的政策等方面因素，使得人才问题一直成为制约陕北能源化工基地发展的瓶颈。在调研的基础上，针对陕北能源化工基地人才供需存在的主要矛盾和问题，提出了解决的思路。     

水热法制备PZT纳米粉体物理化学环境

水热法是制备Pb(Zr0.52Ti0.48)O3(PZT)纳米粉体的一种有效方法,制备的PZT粉体分散性好、粒径小,符合化学计量比,不需要经高温煅烧,烧结活性高。该文基于电解质溶液理论和结晶学的观念,讨论了水热法制备PZT纳米粉体的物理与化学环境的特殊性,分析了PZT纳米晶成核与结晶生长的驱动力。     

榆林能源化工基地的产业结构调整分析

榆林能源化工基地的开发取得了很大进展，但产业结构不合理、产业发展层次低等问题却依然存在，影响了经济的进一步发展。对此，应调整产业发展的方向和目标，促进产业的合理化和高度化，发挥产业竞争力，要根据地区实际情况，优先发展优势产业，调整改造传统农业产业，培育扶持服务、替代产业等途径来调整产业结构，实现社会、经济的可持续发展，确保基地的长期繁荣。     

构建榆林学院校内化工实习实训基地的思考

校内化工实习实训基地是集实习、实训、模拟、设计、中试放大、检测等功能于一体的开放型校内实践教学基地。建设实训基地的主要作用是让学生学习化工生产的基本知识、了解设备原理和工作过程,建立起较完整的化工生产的系统概念;加强学生对有关化工设备的设计、加工、安装及性能测试方面的基本技能和知识。它对进一步培养和提高化工类学生的工程实践能力和创新能力具有很好的促进作用。