Process design for the environment: A multi-objective framework under uncertainty

Designing chemical processes for the environment requires consideration of several indexes of environmental impact including ozone depletion, global warming potentials, human and aquatic toxicity, photochemical oxidation, and acid rain potentials. Current methodologies, such as the generalized waste reduction algorithm (WAR), provide a first step towards evaluating these impacts. However, to address the issues of accuracy and the relative weights of these impact indexes, one must consider the problem of uncertainties. Environmental impacts must also be weighted and balanced against other concerns, such as their cost and long-term sustainability. These multiple, often conflicting, goals pose a challenging and complex optimization problem, requiring multi-objective optimization under uncertainty. This paper will address the problem of quantifying and analyzing the various objectives involved in process design for the environment. Towards this goal, we proposed a novel multi-objective optimization framework under uncertainty. This framework is based on new and efficient algorithms for multi-objective optimization and for uncertainty analysis. This approach finds a set of potentially optimal designs where trade-offs can be explicitly identified, unlike cost-benefit analysis, which deals with multiple objectives by identifying a single fundamental objective and then converting all the other objectives into this single currency. A benchmark process for hydrodealkylation (HDA) of toluene to produce benzene modeled in the ASPEN simulator is used to illustrate the usefulness of the approach in finding environmentally friendly and cost-effective designs under uncertainty.     

Discordant results between fetal karyotyping and non-invasive prenatal testing by maternal plasma sequencing in a case of uniparental disomy 21 due to trisomic rescue

Uniparental disomy (UPD) is an uncommon chromosome condition, but UPD involving chromosome 21 is rarely reported. We reported here a case who had first trimester screening test for Down syndrome, chorionic villus sampling for fetal karyotyping, quantitative fluorescence polymerase chain reaction (QF-PCR), as well as non-invasive prenatal testing (NIPT) by maternal plasma sequencing. There were discordant results between fetal karyotyping and NIPT due to UPD 21combined with confined placental mosaicism of trisomy 21. This demonstrated that it is possible to detect placental mosaicism by NIPT, but further studies are required to confirm its sensitivity. Therefore, all positive NIPT results must be confirmed by conventional invasive test and karyotyping. QF-PCR has the additional benefit in diagnosing UPD. © 2013 John Wiley & Sons, Ltd.     

Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process

Characteristics of toluene decomposition and formation of nitrogen oxide (NOx) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al₂O₃/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO₂ selectivity. In addition, NOx was suppressed with the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NOx suppression. The MnOx catalyst exhibited the lowest concentration of O₃ and highest CO₂ selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.     

Biodegradation of nitrogen-enriched lignite

Biodegradation of nitrogen-enriched lignite by soil bacteria previously acclimated in hydrogen peroxide-acetic acid lignitic substrate was carried out to assess the effects of nitrogen functional groups on the biodegradation of lignite. Chlorination, oxidation plus nitration, and ammoniation were applied in an attempt to modify the chemical structure of lignite so as to obtain a lignitic substrate that is more compatible to the enzymatical system of ordinary soil bacteria than that of unmodified lignite. Incorporation of nitrogen containing functional groups into lignite structure achieved 4.71 wt%, a value five times higher than that usually found in unmodified (raw) lignite. Data collected through a 16 day incubation time, monitoring production as well as depletion of both nitrate and organic acids, concluded that biodegradation was expedited by the incorporation of nitrogen into the structure of lignite. Twenty-eight compounds were identified based on the results from GC/MS analysis of the products.     

检测细胞DNA断裂损伤效应的彗星实验法的改良

为了解决彗星实验过程中常出现的脱胶、细胞核分离操作繁琐、重复性低等问题,对彗星实验方法进行了改良,初步建立了彗星实验的快速操作流程。结果显示,通过对载玻片进行预处理,可确保凝胶悬挂均匀;采用改良机械法分离的细胞核浓度适中;以0.5%(w/v)涂层琼脂糖作为基层、以1.5%(w/v)低熔点包埋琼脂糖作为叠加层的"双层凝胶法",辅以"推片法"铺胶,操作便捷且不发生脱胶现象;细胞核膜经裂解处理后再进行电泳和荧光观察,彗星图像清晰,杂质少。应用改良后的彗星实验方法,操作简便,耗时更短,实验效果良好,可快速检测出细胞DNA损伤效应。     

Immobilization of lead in anthropogenic contaminated soils using phosphates with/without oxalic acid

Understanding the effects of oxalic acid(OA) on the immobilization of Pb(Ⅱ) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(Ⅱ) by KH2PO4, phosphate rock(PR), activated phosphate rock(APR) and synthetic hydroxyapatite(HAP) at different phosphate:Pb(P:Pb) molar ratios(0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or Ca Cl2, Community Bureau of Reference(BCR) sequential extraction and toxicity characteristic leaching procedure(TCLP)methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after120 days was reduced by 100% when soils were amended with APR, HAP and HAP + OA, and the TCLP-Pb was 5 mg/L for the red soil at P:Pb molar ratio 4.0. Water-soluble Pb could not be detected and the TCLP-Pb was 5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APR was most effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pb molar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.