Perfluorinated compounds in the Cape Fear Drainage Basin in North Carolina

Concern over perfluorinated organic compounds (PFCs), e.g., perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), is due to a number of recent studies which show that the PFCs are persistent, bioaccumulative, and toxic in animals. Despite sustained interest in this topic, little information is available concerning the environmental distributions of the compounds. In this study, a new method was developed for the analysis of 10 target PFCs and its performance was examined in a systematic evaluation of surface water in the Cape Fear River Basin in North Carolina. One hundred samples from 80 different locations were collected during the spring of 2006. Detectable levels of the target PFCs were found in all samples, and were comparable to values reported previously, with maximum PFOS at 132 ng/L, PFOA at 287 ng/L, perfluorononanoic acid (C9) at 194 ng/L, and perfluoroheptanoic acid (C7) at 329 ng/L. In general, the lowest concentrations of the PFCs were found in the smallest tributaries while the highest levels were found in middle reaches of the Drainage Basin. Variability of PFC concentrations suggests a series of source inputs throughout the Basin. Seventeen sample sites (22%) had PFOS concentrations greater than 43 ng/L, a conservative safe water concentration estimated to be protective of avian life. In addition, a total of 26 sites (32%) had PFOA concentrations above 40 ng/L.     

Field evaluation of in situ source reduction of trichloroethylene in groundwater using bioenhanced in-well vapor stripping

Two technologies in combination, cometabolic bioremediation and in-well vapor stripping, were applied to reduce trichloroethylene (TCE) concentrations in groundwater at a contaminant source area without the need to pump contaminated groundwater to the surface for treatment. The vapor-stripping well reduced source TCE concentrations (as high as 6-9 mg/L) by over 95%. Effluent from the well then flowed to two bioremediation wells, where additional reductions of approximately 60% were achieved. TCE removal was extensively monitored (for research and not regulatory purposes) using an automated system that collected samples about every 45 min at 55 locations over an area of approximately 50 x 60 m2. During 4.5 months of system operation, total TCE mass removal was 8.1 kg, 7.1 kg of which resulted from in-well vapor stripping and 1.0 kg from biotreatment. The system reduced the average TCE concentration of about 3000 microg/L in the source-zone groundwater to about 250 microg/L in water leaving the treatment zone, effecting greater than 92% TCE removal. A 6 month rebound study after system operation ceased found TCE concentrations then increased significantly in the treatment zone due to diffusion from the fractured rock below and perhaps other processes, with mass increases of about 1.5 kg in the lower aquifer and 0.3 kg in the upper aquifer.     

Elaboration and properties of renewable polyurethanes based on natural rubber and biodegradable poly(butylene succinate) soft segments

Natural rubber (NR) is a renewable bio‐based polymer, while poly(butylene succinate) (PBS) belongs to the family of biodegradable renewable polymers. In this article, novel polyurethanes (PUs) were prepared using hydroxyl telechelic natural rubber (HTNR) and hydroxyl telechelic poly(butylene succinate) (HTPBS) as soft segments, and using toluene‐2,4‐diisocyanate (TDI) and 1,4‐butanediol (BDO) as hard segment. HTPBS oligomers of = 2000 and 3500 g mol^?1 were synthesized by bulk polycondensation of succinic acid (SA) with BDO. The polyurethane materials were obtained by casting process after solvent evaporation. The influence of the hard segment content and the molecular weight of HTPBS on the materials’ thermo‐mechanical properties were investigated by means of tensile testing, DSC, TGA, and DMTA. The obtained polyurethanes were amorphous with phase separations between hard and soft segments as well as between HTNR and HTPBS segments, and they exhibited good physical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42943.     

Potentiostatic electrodeposition of cuprous oxide thin films for photovoltaic applications

Potentiostatic deposition of Cu₂O thin films on glass substrates coated with F-doped SnO₂ from an alkaline electrolyte solution (pH 12.5) containing copper (II) sulfate and lactic acid was studied for fabrication of a Cu₂O/Al-doped ZnO (AZO) heterojunction solar cell. The band gap of the electrodeposited Cu₂O films was determined by photoelectrochemical measurements to be around 1.9 eV irrespective of the applied potentials. The solar cells with a glass/FTO/Cu₂O/AZO structure were fabricated by sputtering an AZO film onto the Cu₂O film followed by deposition of an Al contact by vacuum evaporation. The highest efficiency of 0.603% was obtained with a Cu₂O film deposited at −0.6 V (vs. Ag/AgCl). This was attributed to better compactness and purity of the Cu₂O film than those of the Cu₂O films deposited at other potentials.     

Synthesis of pH-sensitive micelles from linseed oil using atom transfer radical polymerisation (ATRP)

This paper reports the synthesis of an amphiphilic copolymer from linseed oils and its successive auto-association in water into pH-sensitive micelles. An original ATRP lipoinitiator is first designed from linseed oil in two steps. tert-butyl acrylate (tBA) polymerization is consequently initiated from this original initiator and amphiphilic copolymers are obtained after subsequent acidolysis of the PtBA block into poly(acrylic acid) (PAA). The ability of a lipid-b-PAA copolymer to auto-associate in water is finally investigated through different techniques (Fluorescence, Surface Tension, QELS). This copolymer forms well-defined micelles in acidic media with a low critical micellar concentration (cmc) of 7.6 mg L^?1 and dissociates when the pH is raised above 7.     

Monoammonium glycyrrhizinate stability in aqueous buffer solutions

The objective of this research is to evaluate the thermal stability of monoammonium glycyrrhizinate. Thermodegradation of solutions of monoammonium glycyrrhizinate at various temperatures (50, 70 and 90°C) was studied. This degradation appeared to follow first-order kinetics independently of temperature and was found to be pH dependent. The experiments revealed an activation energy (E_a) of about 33 kJ mol⁻¹ and a t_90% of about 3 years at 20°C in a pH range from 7 to 9. So it can be concluded that monoammonium glycyrrhizinate is stable in a pH range from 7 to 9. It can be interesting for use in oral care or in food industry. © 1998 SCI.     

寻找激励和提高员工主动性的最佳途径

在一家大型媒体公司里,所有的高级经理都同意,每个月要花1天时间与客户在一起.某天,一位高级副总裁带着一位地区经理去见客户.这天,他拜访了最后一个客户,也是他们最大的新客户之一,一家准分子激光手术中心.     

Subchannel analysis of CANDU-SCWR fuel

A cooperative study has been initiated at Xi'an Jiaotong University (XJTU) with Atomic Energy of Canada Limited (AECL) to develop a subchannel code ATHAS for preliminary analyses of flow and enthalpy distributions and cladding temperatures in CANDU fuel at super-critical water conditions. The code is applicable for transient and steady-state calculations. Then the paper uses the ATHAS code to analyze CANDU-SCWR which is operating at 25.0 MPa pressure. The results show that the maximum cladding-surface temperature of CANFLEX bundle is 804.1 °C, which is below the limit of design, and it is appropriate for use in the CANDU super-critical water-cooled reactor (SCWR) based on heat-transfer analysis.     

让那些"扼杀"创意反对变革的"洞中人"彻底失势

起关键性破坏作用的那些“对所有人持反对态度的人”,被我们称为“洞中人”,他们不可避免地会“扼杀”创意或改革。要战胜惰性,改进组织执行力,我们首先要：战胜“洞中人”     

Role of Neutrophils and NETs in Animal Models of Thrombosis

Thrombosis is one of the major causes of mortality worldwide. Notably, it is not only implicated in cardiovascular diseases, such as myocardial infarction (MI), stroke, and pulmonary embolism (PE), but also in cancers. Understanding the cellular and molecular mechanisms involved in platelet thrombus formation is a major challenge for scientists today. For this purpose, new imaging technologies (such as confocal intravital microscopy, electron microscopy, holotomography, etc.) coupled with animal models of thrombosis (mouse, rat, rabbit, etc.) allow a better overview of this complex physiopathological process. Each of the cellular components is known to participate, including the subendothelial matrix, the endothelium, platelets, circulating cells, and, notably, neutrophils. Initially known as immune cells, neutrophils have been considered to be part of the landscape of thrombosis for more than a decade. They participate in this biological process through their expression of tissue factor (TF) and protein disulfide isomerase (PDI). Moreover, highly activated neutrophils are described as being able to release their DNA and thus form chromatin networks known as “neutrophil extracellular traps” (NETs). Initially, described as “dead sacrifices for a good cause” that prevent the dissemination of bacteria in the body, NETs have also been studied in several human pathologies, such as cardiovascular and respiratory diseases. Many articles suggest that they are involved in platelet thrombus formation and the activation of the coagulation cascade. This review presents the models of thrombosis in which neutrophils and NETs are involved and describes their mechanisms of action. We have even highlighted the medical diagnostic advances related to this research.