Excited States and Photodebromination of Selected Polybrominated Diphenyl Ethers: Computational and Quantitative Structure—Property Relationship Studies

This paper presents a density functional theory (DFT)/time-dependent DFT (TD-DFT) study on the lowest lying singlet and triplet excited states of 20 selected polybrominateddiphenyl ether (PBDE) congeners, with the solvation effect included in the calculations using the polarized continuum model (PCM). The results obtained showed that for most of the brominated diphenyl ether (BDE) congeners, the lowest singlet excited state was initiated by the electron transfer from HOMO to LUMO, involving a π–σ* excitation. In triplet excited states, structure of the BDE congeners differed notably from that of the BDE ground states with one of the specific C–Br bonds bending off the aromatic plane. In addition, the partial least squares regression (PLSR), principal component analysis-multiple linear regression analysis (PCA-MLR), and back propagation artificial neural network (BP-ANN) approaches were employed for a quantitative structure-property relationship (QSPR) study. Based on the previously reported kinetic data for the debromination by ultraviolet (UV) and sunlight, obtained QSPR models exhibited a reasonable evaluation of the photodebromination reactivity even when the BDE congeners had same degree of bromination, albeit different patterns of bromination.     

Enable high reversibility of Fe/Cu based fluoride conversion batteries via interfacial gas release and detergency of garnet electrolytes

Garnet-type Ta-doped Li₇La₃Zr₂O₁₂ (LLZTO) electrolyte suffers from unstable chemical passivation under air exposure, responsible for the poor interfacial wettability and conductivity with Li metal. Instead of conventional methods to remove surface contaminants by mechanical polishing, acid etching and high temperature reduction, herein we propose a simple strategy of interfacial gas release and detergency to smartly convert Li₂CO₃ passivation layer into ion-conductive Li₃PO₄ domains at mild temperature (∼200 ℃). The in-situ formation of PH₃ vapor and its phosphorization enables a dramatic decrease of Li/garnet interfacial resistance down to 2 Ω cm² at room temperature (RT). The improved interfacial wettability and conductivity endow the symmetric cells with ultra-stable galvanostatic cycling over 1500 h and high critical current density of 2.6 mA/cm². The high coulombic efficiency of Li plating enables a high reversibility of solid-state NCM811/Li cells even under a low N/P ratio (∼4) and high cut-off voltage of 4.5 V at RT. The prototype of fluoride-garnet solid-state batteries are successfully driven as rechargeable system (rather than widely known primary battery) with high conversion capacity (400 ∼ 500 mAh/g) and high-rate performance (251.2 mAh/g at 3 C). This interface infiltration-detergency approach provides a practical solution to the achievement of high-energy solid-state Li metal batteries.     

Olfactory responses of Stegobium paniceum to different Chinese medicinal plant materials and component analysis of volatiles

Stegobium paniceum (L.) (Coleoptera: Anobiidae) is among the major pests of stored products, causing great damage to stored Chinese medicinal plant materials (CMPMs) in China. Effective control strategies are urgently needed. The aim of this study was to explore the role of volatile organic compounds in the host preference of S. paniceum. First, the olfactory behavioral responses of S. paniceum adults to volatiles from four CMPMs (Panax notoginseng, Angelica sinensis, Gastrodia elata, and Peucedanum praeruptorum) were tested in Y-tube olfactometer experiments. Then, the volatile composition of these plant materials were analyzed by gas chromatography-mass spectrometry (GC-MS). S. paniceum showed significant preferences for volatiles from the four CMPMs, compared with clean air (CA). When S. paniceum was presented with choices among different CMPMs, it showed the strongest preference for P. notoginseng, followed by A. sinensis, then G. elata, and P. praeruptorum. GC-MS analysis identified 43, 34, 28 and 60 components in the volatile profiles of P. notoginseng, A. sinensis, G. elata, and P. praeruptorum, respectively. Falcarinol (14.4%), 3-n-butyl phthalide (78.7%), p-cresol (40.1%), and β-pinene (29.1%) were the most abundant components of the volatiles of P. notoginseng, A. sinensis, G. elata, and P. praeruptorum, respectively. The olfactory responses of S. paniceum to the four CMPMs demonstrated that host-related volatiles play an important role in the host-searching process by adult beetles. This information will be useful for the development of safe and effective trapping strategies for this pest.     

Significant population structure in Australian Cryptolestes ferrugineus and interpreting the potential spread of phosphine resistance

An analysis of the population genetics of Cryptolestes ferrugineus, across all major regions in Australia where grain is grown and stored in bulk, provides an initial step in investigating the movement of these insects and implications for the spread of phosphine resistance. Microsatellite data revealed two levels of genetic structure. Across Australia, two clusters were detected, one in eastern Australia (Queensland, New South Wales, Victoria and Tasmania) and Western Australia (Cluster 1) and one in South Australia (Cluster 2). Intermediate between them, in eastern South Australia, are a couple of populations that are equally admixed for the two clusters. Populations in Western Australia and western SA belong to different clusters suggesting that the extensive and arid Nullarbor Plain restricts the natural dispersal of these beetles. Isolation-by-distance and the detection of clustering among local populations suggests there is considerable gene flow at a local scale in C. ferrugineus, and we infer this is by flight. Limited natural gene flow between eastern and western Australia might, in part, explain why extremely high resistance has not been detected in Western Australia.     

Reactivity between carbon cathode materials and electrolyte based on industrial and laboratory data

Interaction between electrolyte and carbon cathodes during the electrolytic production of aluminium decreases cell life. This paper describes the interaction between carbon cathode materials and electrolyte, based on industrial and laboratory data. It also reports on the degree of expansion of semi-graphitic and graphitised materials when exposed to a sodium rich environment. Phase relations in the slow cooled bath electrolyte, spent industrial cathodes and laboratory scale cathode samples were similar: all contained Na₃AlF₆, NaF, CaF₂ and NaAl₁₁O₁₇. Al₄C₃, AlN and NaCN were only detected in the spent industrial cathodes. The inability to locate Al₄C₃ in the laboratory scale samples could be due to very low concentrations of Al₄C₃ which could not be detected by XRD, or to the limited direct contact between the produced aluminium and carbon material. X-ray diffraction analysis confirmed that sodium intercalation into graphite did not take place. Wear of the examined carbon cathodes proceeded due to penetration of electrolyte and sodium into the cathode, followed by reactions with carbon and N₂ whereby AlN and NaCN formed. Once electrolysis started the carbon cathodes expanded rapidly, but slowed down after approximately an hour. Sodium expansion decreased with degree of graphitisation of the carbon cathode material.     

云南东川拖布卡-播卡金矿与汤丹铜矿区苔藓植物比较研究

拖布卡-播卡金矿为一世界级大型金矿,位于云南省昆明市东川区.经野外采集及室内鉴定,发现其上分布着3科(丛藓科、真藓科和金发藓科)10属(对齿藓属、扭口藓属、真藓属、短月藓属等)19种苔藓植物.经与气候条件相似的东川汤丹大型铜矿上分布的苔藓植物比较发现:共同种有5种,种类相似性较小,种的相似性系数为24%;拖布卡-播卡金矿种类丰富度小于汤丹铜矿;生活型较为单调,几乎都是矮丛集型;区系成分以世界广布种为主.可见,同样的气候条件下含不同重金属基质对于苔藓植物具有不同的选择性.拖布卡-播卡金矿上剑叶对齿藓Didymodon rufidulus Broth.、云南墙藓Tortul(a) yunnanensis Chen和东亚小金发藓Pogonatum inflexum Lac.分布较为广泛,可作为进一步研究生物探矿的材料.     

通过DOM的光谱特性对长江源头典型高原深水湖泊进行评价

天然溶解有机质(dissolved organic matter,DOM)研究在水体生态环境系统的修复研究中扮演着重要的角色,是近年来水环境研究领域的一个热点和难点。目前,紫外?可见光谱和分子荧光光谱在天然溶解有机质是表征天然溶解有机质的重要有效的手段,也是研究天然溶解有机质的主要手段。红枫湖为贵阳市5个主要饮用水源地之一,对贵阳市社会发展具有重要作用。采用紫外?可见光谱和分子荧光光谱相结合的研究方法,对采自红枫湖中10个点的水样中天然溶解有机质的光谱特性研究。研究结果表明,红枫湖水体光谱特征主要表现为紫外?可见吸光值参数E3/E4的变化范围是1.70~8.77。除后五火电厂外,水下10 m比水下5 m的E3/E4值要高。此外,荧光指数f450/500的变化范围是1.38~1.52。初步认为红枫湖目前的主要有机物污染是陆源性的。后五火电厂,北湖湖心和张官三点水样的光谱特征与其他地方不同。同时还表明溶解有机质的腐殖化程度与水深具有一定的相关性。     

Footprint of harmful substances in spent pot lining of aluminum reduction cell

Spent pot lining (SPL) from aluminum reduction cells is considered to be hazardous materials due to containing a large amount of soluble fluoride salts and trace toxic cyanides. The distribution of fluorides and cyanide in a 350 kA cell operated for 2396 days was analyzed and the footprint and corrosion mechanism of the harmful substances in SPL were also studied. It is found that the fluorides are mainly concentrated in the cathode carbon block and the layer of dry barrier under the cathodes, which is closely related to permeability of the cathodes and dry barrier the fluorides penetrate in. Cyanide has a low concentration in the cell center and a high concentration in the sidewall, which is positively related to the air amount entering into the areas in the cells.     

Feeding substrate and temperature interplay determining infestations and losses by the sawtoothed grain beetle (Oryzaephilus surinamensis)

Sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), is a secondary pest of stored products and one of the serious insect pests of cereal grains, commodities and packaged food throughout the world. However, this species is a concern beyond cereal grains, what may be differentially affected by temperature. Therefore, insect developmental time, larva and pupa survival, and adult emergence of O. surinamensis were assessed on different substrates (rice, sesame and date palm) at different temperatures (20, 25, 30 and 35 °C and 65% r.h). The substrate loss incurred by this insect infestation was also recorded. The larval stage was the main determinant for the overall developmental time of the sawtoothed grain beetle, regardless of the substrate and temperature tested. Adult emergence was affected by substrate (F_2,48 = 4.50, P = 0.02) and particularly temperature (F_3,48 = 24.94, P < 0.001), but not their interaction (F_6,48 = 0.40, P = 0.87), exhibiting little variation until reaching 30 °C, but with a quick decline at 35 °C. The performance of the insects in rice was better, and worse in dry date. Furthermore, the survival was inversely related to substrate loss, regardless of the substrate used for rearing the sawtoothed grain beetle. Thus, substrate and temperature range are major determinants of sawtoothed grain beetle infestation with consequences for this species management.