Adsorption of 2,4,6-trichlorophenol by multi-walled carbon nanotubes as affected by Cu(II)

Adsorption equilibrium of 2,4,6-trichlorophenol (TCP) on multi-walled carbon nanotubes (MWCNTs) was investigated to explore the possibility of using MWCNTs for concentration, detection and removal of TCP from contaminated water. The adsorption of TCP on MWCNTs at pH 4 was nonlinear, reversible and best fit by a Polanyi-Manes model. Oxidation treatment increased surface area and introduced hydrophilic carboxylic groups to the defect sites of MWCNTs, hence increased the sorption of TCP and Cu(II) individually. Cu(II) suppressed the sorption of TCP on oxidized MWCNTs15A, but had little effect on as-grown MWCNTs15. TCP had no influence on Cu(II) sorption to either. The mechanisms of Cu(II) suppression effect on TCP adsorption are ascribed to the formation of surface complexes of Cu(II), which was verified by X-ray absorption spectroscopy. Cu(II) exerts a cross-linking effect of functional groups on adjacent tubes, creating a more tightly knit bundle and suppressing the condensation of TCP in the pore spaces between the tubes. The large hydration sphere around surface complexes of Cu(II) may also intrude or shield hydrophilic sites, leading to the “crowding out” of TCP around the Cu(II)-complexed sites.     

Structural investigation of a novel fucoglucogalactan isolated from the fruiting bodies of the fungus Hericium erinaceus

A new heteropolysaccharide with a molecular weight of 1.94 × 10⁴ Da, HEPF1, was isolated from the fruiting bodies of Hericium erinaceus. It is composed of fucose, galactose and glucose in the ratio of 1:4:1, as well as a minor proportion of 3-O-methyl rhamnose. Sugar analyses, methylation analysis, together with ¹H and ¹³C NMR spectroscopy established that HEPF1 has a (1 → 6)-linked α-d-galactopyranosyl backbone with branches that are composed of fucose attached to O-2; it also contains 6-O-substituted-β-d-oligoglucosyl units and a minor terminal 3-O-methyl rhamnose residue.     

Antioxidant capacities vary substantially among cultivars of rabbiteye blueberry (Vaccinium ashei Reade)

Fruits from forty‐two blueberry cultivars, including thirty‐six rabbiteye (Vaccinium ashei Reade), three V. ashei hybrid derivatives and three northern highbush (V. corymbosum L.) standards, were evaluated for their antioxidant activities against peroxyl free radicals (ROO˙), hydroxyl radicals (OH˙), hydrogen peroxide (H₂O₂), superoxide radicals () and singlet oxygen (¹O₂) radicals. The differences in scavenging capacities for these radicals among forty‐two selected blueberry cultivars were significant. Oxygen radical absorbance capacity values ranged from 33.8 to 118.7 μmol Trolox equivalents (TE) g fresh wt^?1, 196.1 to 518.8 μmol TE g dry wt^?1 and 7.1 to 22.2 μmol cm^?2‐surface area. Extracts from fruit of pure rabbiteye had higher levels of scavenging capacities of oxygen species , ¹O₂ and H₂O₂ compared to V. ashei hybrid derivatives and northern highbush blueberry standards. The rabbiteye cultivars ‘Early May’ and ‘Centurion’ had the highest scavenging capacity for the reactive oxygen species, not only for ROO˙ and ˙OH, but also for , ¹O₂ and a strong oxidant, H₂O_2. In contrast, ‘Pink Lemonade’ (pink‐fruited) had the lowest ability to inhibit free radical activity of ROO˙,˙OH, ¹O_2, and H₂O_2.‘Snowflake’ had the lowest scavenging capacity for . Blueberry cultivars with high antioxidant activity and radical scavenging capacity have potential to improve human health and can possibly be used as parents for future blueberry breeding programs to develop new blueberry cultivars with higher antioxidant activity.     

茶褐素的提取纯化与生理功效研究进展

茶褐素作为黑茶中重要的功能成分,是一类溶于水而不溶于乙酸乙酯和正丁醇等有机试剂的褐色高聚物,属于多酚类物质,具有酚类物质特性。茶褐素具有显著的降脂减肥功效,但是茶褐素结构和组成复杂,导致对其提取纯化和功效研究还不够深入。本文综述了近几年茶褐素的试剂提取、微波和超声波辅助提取、膜分离和柱层析等提取纯化研究,以及茶褐素在降脂减肥、抗氧化、抗癌、抗疲劳、调节体内微量元素含量等功效的研究现状。比较了几种分离纯化方式的优缺点,展望了茶褐素组成的研究方法、其他功效的研究方向和相关产品、保健品的开发,为茶褐素的深入研究提供了参考。     

Pesticide residues in the spring cabbage (Brassica oleracea L. var. capitata) grown in open field

A method was established to evaluate multi-residual dynamics of the pesticides (chlorpyrifos, dimethoate, cyhalothrin, cypermethrin, fenvalerate, deltamethrin and chlorothalonil) in the spring cabbage, Brassica oleracea L. var. capitata. The results showed that the pesticide residues were closely related with the times and dosage of application, and the weather after spraying. The half-lives of the seven pesticides in the vegetable were 2.0, 1.6, 1.6, 2.3, 2.2, 1.5 and 1.8 days, respectively. If the cabbages were treated one time at normal dosage of pesticides, and all pesticides maximum residue limits (MRLs) were not exceeded according to the recommended pre-harvest interval. However, if the vegetables were treated four times at the maximal dosage with a five-day’s interval, the half-lifes of chlorpyrifos, cypermethrin and chlorothalonil in the vegetable were 2.9, 2.6 and 4.1 days, respectively, and the final residual amount of chlorothalonil exceeded its MRL on cabbage, but the final residual amounts of cypermethrin and chlorpyrifos were below its MRLs on the cabbage. Furthermore, in both one-time and four-time spraying treatments, the final degradation rates of pesticides residues were above 80%.     

Human and social behavior in computational modeling and analysis of egress

Safe egress is one of the key design issues identified by facility planners, manager and inspectors. Computational tools are now available for the simulation and design of emergency evacuation and egress. However, these tools rely heavily on assumptions about individual human and social behaviors, which have been found to be oversimplified, inconsistent and even incorrect. Furthermore, the behaviors are usually incorporated into the computational model in an ad hoc manner. This paper presents a framework for studying human and social behavior, from the perspectives of human decision-making and social interaction, and for incorporating such behavior systematically in a dynamic computational model suitable for emergency egress analysis.     

Viscosity transition of ZnO-containing rosin

Eutectic alloy Sn–9Zn is regarded as one of the potential substitutes for Pb-containing solders, although it has some drawbacks yet to overcome. One of the problems involved is drastic viscosity increase of rosin-based flux during soldering or storage. In the present work we investigated the role of ZnO in the viscosity transition of rosin. The results show that the viscosity transition is directly caused by the presence of ZnO in molten rosin and, at a certain temperature, there exists a critical ZnO concentration for its occurrence. The critical ZnO concentration increases with temperature. A graph is presented to show the conditions for the viscosity transition, in a ZnO concentration–temperature space. The transition is found to be reversible when shifting temperature or ZnO concentration across the boundary and to assume the features of a thermally activated phase transformation.     

Effect of additives on the WGS activity of combustion synthesized CuO/CeO2 catalysts

This paper presents a study on the role of additives (samaria, lanthana, zirconia, and zinc oxide) to ceria as a support of copper catalysts for low-temperature WGSR. A single-step urea-combustion procedure was used for preparation of highly active catalysts. The results revealed the beneficial role of Sm₂O₃ and ZnO doping in increasing BET surface area and total pore volume of the catalysts and decreasing the degree of crystallinity of ceria. TPR profiles evidenced enhanced reducibility of modified catalysts. The WGS activity of these catalysts correlates well with BET, XRD, and TPR data. By comparing the catalysts with a commercial CuO–ZnO–Al₂O₃ sample we point out the feasibility of using CuO/doped-ceria catalysts for low-temperature WGSR.     

γ辐射对大麦过氧化物酶同工酶谱和染色体畸变率的影响

23个大麦品种干种子经γ射线辐照后,其幼苗组织中的过氧化物酶同工酶谱在偏负极端R_f0.29—0.38出现新的酶带,根尖细胞出现各种染色体结构变异,酶带数目和畸变细胞率的辐射剂量效应均可用线性回归方程Y=Ax+B拟合。对供试品种属性的分类分析表明皮大麦的辐射敏感性低于裸大麦,二梭大麦低于四棱和六棱大麦。     

青砖茶的加工工艺、品质及生理作用研究进展

青砖茶属于黑茶类,产自于我国鄂南地区,是边疆少数民族不可或缺的生活饮品。通常以老青茶为原料,经毛茶初制、增湿渥堆、复制拼配、蒸压成型和烘房干燥这五道工序加工制成。其中最关键的步骤为增湿渥堆,这一过程中茶叶内含成分的转化情况直接影响青砖茶的品质。对其品质的分析,一般先从色泽、滋味、香气等方面进行感官审评,再通过检测茶叶中的茶多酚、咖啡碱、可溶性糖以及香气活性成分等物质含量来综合评定。优质的青砖茶外形平整、茶汤色泽透亮、滋味醇厚、陈香悠长,因此深受人们喜爱。此外,青砖茶还具有抗氧化、抗肥胖、降血脂以及调节肠道菌群等多种生理功效,极具开发价值。本文综述了青砖茶的加工工艺、品质特性和生理功效的研究进展,以期为青砖茶品质的提升及其保健功效的深入研究提供理论依据。