Chemical safety levels (CSLs): A proposal for chemical safety practices in microbiological and biomedical laboratories

Microbiological and biomedical laboratories handle chemicals of various hazards in many diverse ways and quantities. Although there are biosafety levels that classify laboratories by the hazard of the biological agent and its use, there are no similar guidelines for classifying chemical safety practices. We propose a system for using chemical safety levels (CSLs) in these laboratories. These CSLs, CSL1 (low risk), CSL2 (moderate risk), CSL3 (substantial risk), and CSL4 (high risk), are classified by the chemical hazards and the nature of the work in which these chemicals are used in the laboratory. Risk at each CSL is governed by limiting or restricting chemical usage or type of work. Standard and CSL specific safe practices, equipment, and facilities requirements are proposed. This work is presented as a starting basis for developing a CSL system, and additional details and modifications will be finalized through a pilot project.     

羰基合成高碳醇工艺研究进展

综述了对液/液两相催化高碳烯烃氢甲酰化制备高碳醇的研究进展,针对经典的水/有机两相体系不能用于催化高碳烯烃氢甲酰化的问题,全面介绍了适用于水/有机两相体系中高碳烯烃氢甲酰化的温控相转移催化法等6种改进方法。同时对氟两相、离子液体两相、超临界流体等非水液/液两相体系中的高碳烯烃氢甲酰化作了系统阐述,并对它们的应用前景进行了评价。     

Accident simulation as a tool for assessing and controlling environmental risks in chemical process industries: A case study

Accidents involving toxic releases, explosions, and fires in chemical process industries take a heavy toll of property, human lives, and environment quality. If one could forecast the accidents likely to occur and the damage they were likely to cause, one could devise appropriate strategies to prevent the accidents and contain the damage that did occur. Using this concept, we have developed a computer-automated tool for accident simulation. In this paper the applicability of the concept and the tool is described on the basis of a case study of a typical petrochemical industry. The study reveals that out of eight credible accident scenarios, four would be ’stand-alone’ events, whereas four others would also cause secondary or higher order accidents (domino effects). Of the accidents in the former category, the one as per scenario 8 is the worst as it would adversely impact (within the set limit of 50 % probability of causing lethality) larger areas than the other three such accidents. Among the second category, scenario 1 would be the most undesirable because it would simultaneously cause heat radiation, shock waves, and missile effects over a larger area.     

In situ diagnosis of chemical species for the growth of carbon nanotubes in microwave plasma-enhanced chemical vapor deposition

A synthesis of multi-wall carbon nanotubes (MWNTs) by microwave plasma-enhanced chemical vapor deposition using CH₄/H₂/NH₃ gases on Ni/Cr-coated glass at low temperature, was investigated by optical emission spectroscopy (OES) and quadrupole mass spectroscopy (MS). It was observed that the MWNTs were grown within a very restrictive range of the gas compositions. Optical emission lines were observed primarily from atomic hydrogen H_α, molecular hydrogen, and CN radicals. The quadrupole mass spectrum also showed the formation of C₂H₂ and HCN. An addition of a small amount of NH₃ resulted in a decrease of C₂H₂, which could be used to estimate amounts of carbon sources present in the plasma for the growth of MWNTs, and increases of CN and H_α radicals acting as etching species of amorphous carbon. These results show that the etching species of amorphous carbon as well as the growth species are necessary and the ratio between two species have to be in appropriate condition for the synthesis of carbon nanotubes at low temperature. The optimum C₂H₂/H_α ratio in the gas mixture for the growth of MWNTs at low temperature was found to be 1:5 in this study.     

高职化工专业产学结合人才培养思路的探索

职业教育是国民教育体系和人力资源开发的重要组成部分,肩负着培养多样化人才、传承技术技能、促进就业创业的重要职责,必须高度重视、加快发展。职业教育的基本属性和自身的特点,以及其自身发展规律决定了产学结合是高职院校成长的基本规律,校企合作是现代高等职业教育发展的必然趋势。文章就产学结合在高职教育中的重要性以及其在甘肃省的发展现状等方面做一综述,并对未来发展做出了展望。     

Formulation for chemical EOR: Development and evaluation of an ASP formulation In customer field conditions

Alkali surfactant polymer (ASP) flooding is an enhanced oil recovery (EOR) technology with an impressive potential for increasing incremental oil production from conventional hydrocarbon bearing reservoirs. A challenge to ASP application is the complexity of determining an effective formulation, typically requiring extensive laboratory screening of nearly countless combinations of surfactants and cosolvents. This paper focuses on demonstrating the utility of the hydrophilic–lipophilic deviation (HLD) concept for EOR application to simplify surfactant formulation workstreams seeking an economically viable ASP formulation for field application. In describing work performed for EOR application of ASP under customer conditions using crude oil, the discussion covers the initial evaluation of the promising surfactant formulation (interfacial tension and solubility), the improvement upon the formulation via HLD principles, and the evaluation of the improved surfactant formulation (coreflood studies). The final ASP formulation identified consisted of a 9 to 1 mixture of alkyl propoxy sulfate sodium salt (APS) to alkyl ethoxy sulfate sodium salt (AES) totaling 2000 ppm active surfactant content, 2.0 wt% Na₂CO₃, and 3000 ppm polyacrylamide polymer (all commercially available products). This formulation had ultra-low interfacial tension and favorable mixing behavior under reservoir conditions. In coreflood studies, the final formulation reproducibly achieved cumulative oil recovery of 96.4%–98.5% of original oil in place with only 0.3 PV of ASP injection with a chase alkali polymer injection.     

Spline collocation method for solving parabolic PDE's with initial discontinuities: Application to mixing with chemical reaction

A spline collocation method is used to numerically evaluate solutions to nonlinear parabolic partial differential equations where steep gradients characterize the solution profile. A general algorithm is developed that can handle the division of the problem domain into a number of subregions (finite elements) over each of which the solution is found by an orthogonal collocation technique and connected by weak spline conditions. Our method is illustrated by application to a mixing-disguised competitive-consecutive chemical reaction (Ott and Rys, 1975) and is found to be a much more efficient computational technique relative to the previously used methods.     

The chemical modification of enzymes to enhance solubilization in organic solvents for interaction with coal

Some enzymes can effectively function as catalysts in contact with organic solvents in a variety of ways; however, it is desirable to utilize the enzyme in a soluble form for interactions with a solid substrate such as coal. Dinitrofluorobenzene (DNFB) has been used as the reagent to add dinitrophenyl groups to enzymes, thus increasing hydrophobicity and solubility (up to 20 mg ml⁻¹) in less-polar organic solvents ranging from dioxane to benzene. Mixed reducing enzymes modified by DNFB and used in pyridine or benzene under hydrogen have been shown to enhance significantly the solubility in organic solvents of coals ranging from lignite to bituminous, with up to 35.3 wt% coal conversion. A fluidized-bed bioreactor appears to be the most effective contactor.     

Consideration to the Mass Distribution of Fragments by natural-fragmentation in combination with preformed fragments

The empirical formula for the distribution of fragments from rotationally-symmetric, cylindrical warheads can be extended to the case high explosive shells. The parameters arising from this can be determined by fitting the measured results to the theoretical values. In this work possible methods of performing such a fitting procedure are discussed.     

Vanadia/silica model catalyst: AFM and XPS investigation of morphological and chemical changes occurring upon exposure to different gas atmospheres

A model vanadia/silica interface has been prepared by vapour deposition of vanadium-oxy-triisopropoxide onto the native oxide layer of a silicon wafer. The VO _x /SiO₂/Si model system has been used to investigate the morphological and chemical changes occurring with vanadia/silica catalysts when they are exposed to different gas atmospheres. Atomic force microscopy and X-ray photoelectron spectroscopy have been used to follow these changes. The studies show that exposure of the vanadia/silica interface to conditions prevailing during the selective reduction of NO by NH₃ results in temperature dependent morphological changes, while the oxidation states of the vanadia species reflected by the ratio V(III)/V(V) change only little during the surface reconstruction.     

从多尺度到介尺度——复杂化工过程模拟的新挑战

化工过程普遍面对具有多尺度结构的复杂系统,而作为从基本单元相互作用形成系统整体行为与功能的关键环节,介尺度结构对化工过程的定量描述和定向调控具有重要意义。同时,化学、材料、生物、物理和系统科学等领域也都逐步认识到各自的介尺度问题及其共同特性。这表明对介尺度结构与行为共性的深入研究将对科学界产生全局性的影响,同时也表明这样的研究必须通过多学科充分交流、紧密合作才能取得重大进展。本文试图从多尺度研究的背景出发探讨化工及相关过程中介尺度模拟的意义、挑战和方法,并展望其发展。     

Environmentally benign chemical additives in the treatment and chemical cleaning of process water systems: Implications for green chemical technology

Supersaturated process waters high in silicates frequently result in deposition of colloidal silica or metal silicate salts. Silica cannot be inhibited by conventional phosphonate mineral scale inhibitors. Chemical cleaning poses hazards and requires operational shut-downs. This paper is focused on a dual approach for silica scale control, inhibition of colloidal silica formation and colloidal silica dissolution in water technology applications by use of designed chemical approaches. The additives used for silica inhibition were polyaminoamide dendrimers (PAMAM) and polyethyleneimine (PEI), in combination with carboxymethyl inulin (CMI) and polyacrylate (PAA) polymers. In principle, silica inhibition is a function of time and inhibitor dosage. Amine-terminated PAMAM-1 and 2 dendrimers as well as PEI combined with anionic polymers, such as CMI and PAA, seem to have a significant inhibitory effect on silica formation, most likely at its earlier stages where the reaction products are oligomeric silicates. CMI and PAA assist the inhibitory action of PAMAM-1 and 2 and PEI by alleviating formation of insoluble SiO₂-PAMAM precipitates. This most likely occurs by partial neutralization of the positive charge that exists in –NH⁺₃ surface groups. Increase of anionic polymer dosage above a certain threshold has a detrimental effect on the activity of the cationic inhibitors. In that case the polymer’s negative charge “overwhelms” the cationic charge of the inhibitor and poisons its inhibition ability. For silica dissolution, acetic, oxalic, citric acids, histidine and phenylalanine were used as potential replacements of ammonium bifluoride (NH₄F·HF). Silica dissolution is dependent in a rather unpredictable fashion on the structure of the dissolver, time and dosage. This paper continues our research efforts in the discovery, design and application of antiscalant additives that have mild environmental impact. These chemicals are also known as “green additives”.     

Block copolymers of polycarbonates with several hydroxy-terminated elastomers to yield thermoplastic elastomers for higher service temperature

The synthesis of block copolymers and the study of their morphology were undertaken to find improved thermoplastic rubbers for service at elevated temperatures. The basis was the extraordinary properties possessed by ABA-type block copolymers in which the terminal blocks are polystyrene and the central block is either polyisoprene or polybutadiene. In these systems it has been well established that the unusual properties are a result of domain formation in which the hard and the soft blocks aggregate separately into distinct phases. The hard segment is thought to act both as a crosslink and as a filler. Block copolymers were synthesized with different soft and hard segments. The effects of these segments and of their properties on the morphology and the stress-strain properties of the block copolymers were measured and evaluated. Electron microscopy and birefringence were used to determine the morphology. It was found that the glass transition temperatures of the segments, the bulk of the monomer unit in the glassy segment, and the morphology determined the strength of the material. Some of the materials prepared have tensile strengths of 0.1 kg/cm² or more at temperatures in excess of 180°C and therefore appear promising as elastomers for service at elevated temperatures.     

New approaches to water purification for resource-constrained settings: Production of activated biochar by chemical activation with diammonium hydrogenphosphate

A significant portion of the world’s population does not have access to safe drinking water. This problem is most acute in remote, resource-constrained rural settings in developing countries. Water filtration using activated carbon is one of the important steps in treating contaminated water. Lignocellulosic biomass is generally available in abundance in such locations, such as the African rain forests. Our work is focused on developing a simple method to synthesize activated biochar from locally available materials. The preparation of activated biochar with diammonium hydrogenphosphate (DAP) as the activating agent is explored under N₂ flow and air. The study, carried out with cellulose as a model biomass, provides some insight into the interaction between DAP and biomass, as well as the char forming mechanism. Various characterization techniques such as N₂ physisorption, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy are utilized to compare the properties between biochar formed under nitrogen and partial oxidative conditions. At a temperature of 450 °C, the loading of DAP over cellulose is systematically varied, and its effect on activation is examined. The activated biochar samples are predominantly microporous in the range of concentrations studied. The interaction of DAP with cellulose is investigated and the nature of bonding of the heteroatoms to the carbonaceous matrix is elucidated. The results indicate that the quality of biochar prepared under partial oxidation condition is comparable to that of biochar prepared under nitrogen, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained settings.     

我国总图专业同国际接轨的思考

简介总图运输专业性质及其发展过程 ;就目前国内该专业现状 ,论述如何同国际接轨的问题并提出了建议。     

How to implement environmental considerations in chemical process design: An approach to multiobjective optimization for undergraduate students

This paper expects to give some guidelines for undergraduate students about how to implement environmental considerations in chemical process design and how the introduction of these issues could have an important effect on the results obtained in the multiobjective problem optimization when economic and environmental aspects are considered simultaneously.For this work, a representative flowsheet of many chemical and petrochemical processes has been considered. This processing scheme works with a feedstock containing some inert and with not very high conversion per pass in the reactor.Therefore, the influence of the quality of raw materials, the installation of additional stages for treating effluents, the environmental impact and the optimum conversion of the chemical process are evaluated, attending both environmental and economic criteria.Our goals were, first to show how to identify the tradeoffs of a representative chemical process when environmental and economic considerations are included simultaneously in the design and its optimization. Secondly, how feedstock quality and additional waste treatment stages affect to the results obtained in the multiobjective optimization: minimize the total cost of the installation and its environmental impact.As a result, the final objective of this paper is to teach undergraduate students how multi-objective optimization could be used to make better decisions in the design of chemical processes, taking into account both economic (minimum total cost) and environmental (minimum environmental impact) performances.For each case study proposed, a detailed optimization was performed to determine Pareto curves using the ?-constraint method to identify the tradeoffs of this multiobjective optimization and ultimately determine the best alternatives, and even their optimum operational conditions attending to both criteria.It is important to remark that this problem could be solved in Excel so that it could be a good example to undergraduate students.     

Studies related to the structure and reactivity of coals : 18. The chemical structures of products from reactions of a suite of higher rank Australian coals

The structure of the oils, asphaltenes and residues obtained by the thermal reactions of a suite of Australian higher rank coals under hydrogen or nitrogen have been studied by chemical and spectroscopic methods. The host-guest model that has been used to describe the structure of Australian brown coals cannot be applied directly to the higher rank coals. Evidence is provided that suggests that a modified version of the model may be of use in describing the structure of some subbituminous coals. The methodology has proved to be useful in the understanding of structural features of coals which are often not rank dependent, e.g. Callide coal (ABL2), a subbituminous coal, has been shown to have characteristics of both very high and also low rank coals.     

In utero exposure to a low concentration of diesel exhaust affects spontaneous locomotor activity and monoaminergic system in male mice

Background

Epidemiological studies suggest that inhalation of carbonaceous particulate matter from biomass combustion increases susceptibility to bacterial pneumonia. In vitro studies report that phagocytosis of carbon black by alveolar macrophages (AM) impairs killing of Streptococcus pneumoniae. We have previously reported high levels of black carbon in AM from biomass smoke-exposed children and adults. We therefore aimed to use a mouse model to test the hypothesis that high levels of carbon loading of AM in vivo increases susceptibility to pneumococcal pneumonia.

Methods

Female outbred mice were treated with either intranasal phosphate buffered saline (PBS) or ultrafine carbon black (UF-CB in PBS; 500 μg on day 1 and day 4), and then infected with S. pneumoniae strain D39 on day 5. Survival was assessed over 72 h. The effect of UF-CB on AM carbon loading, airway inflammation, and a urinary marker of pulmonary oxidative stress was assessed in uninfected animals.

Results

Instillation of UF-CB in mice resulted a pattern of AM carbon loading similar to that of biomass-smoke exposed humans. In uninfected animals, UF-CB treated animals had increased urinary 8-oxodG (P = 0.055), and an increased airway neutrophil differential count (P < 0.01). All PBS-treated mice died within 72 h after infection with S. pneumoniae, whereas morbidity and mortality after infection was reduced in UF-CB treated animals (median survival 48 h vs. 30 h, P < 0.001). At 24 hr post-infection, UF-CB treated mice had lower lung and the blood S. pneumoniae colony forming unit counts, and lower airway levels of keratinocyte-derived chemokine/growth-related oncogene (KC/GRO), and interferon gamma.

Conclusion

Acute high level loading of AM with ultrafine carbon black particles per se does not increase the susceptibility of mice to pneumococcal infection in vivo.