Preparation and characterization of uniform molecularly imprinted polymer beads for separation of triazine herbicides

Uniform molecularly imprinted polymer beads were synthesized by precipitation polymerization for separation of triazine herbicides. A series of imprinted polymers were prepared using ametryn as template and divinylbenzene as crosslinking monomer, in combination with three different functional monomers under different solvent conditions. Under optimized reaction conditions, we obtained uniform molecularly imprinted polymer microspheres that display favorable molecular binding selectivity for triazine herbicides. The imprinted polymer beads synthesized using methacrylic acid as functional monomer in a mixture of methyl ethyl ketone and heptane showed the best results in terms of particle size distribution and molecular selectivity. Compared with nonimprinted polymer microspheres, the imprinted microspheres displayed significantly higher binding for a group of triazine herbicides including atrazine, simazine, propazine, ametryn, prometryn, and terbutryn. For the first time, precipitation polymerization has been used to produce highly uniform imprinted microspheres suitable for affinity separation of triazine herbicides. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Factors affecting the occurrence and transport of atmospheric organochlorines in the china sea and the northern Indian and South East atlantic oceans

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are reported in 97 air samples collected on board the RV Polarstern in November 2007 from the equator to Cape Town, South Africa and the MV Oceanic II (The Scholar Ship) in January-March 2008 from Shanghai, China to Cape Verde in the Central Atlantic Ocean. The atmospheric concentrations were higher close to the coast and lower in remote regions of the Indian and South Atlantic Ocean. Groups of samples were selected in the South China Sea, Indian Ocean and South Atlantic Ocean where the relative wind direction matched the trajectory of the ship, thus all the samples had the same input of sources upwind. In these three regions the concentrations of OCPs and PCBs declined during atmospheric transport following first order kinetics. These sets of measurements provided estimates of field derived residence times (FDRTs) for individual compounds. These values were compared with predicted atmospheric residence times (PARTs) computed using a model of long-range atmospheric transport potential of POPs. The FDRTs are 5-10 times longer for the more volatile PCB congeners and TC, CC, p,p'-DDT and p,p'-DDE than the respective PARTs, while they are similar to PARTs for the less volatile compounds. Possible causes of discrepancies between PARTs and FDRTs are discussed, and revolatilization from the ocean surface seems to be the main cause for the higher values of FDRTs of the more volatile compounds in comparison with the respective PARTs.     

Metabolic activity and symbiotic interactions of lactic acid bacteria and yeasts isolated from water kefir

Water kefir is a mildly sour and alcoholic drink fermented by a stable microbial multispecies community. With its high sugar content and low amino acid concentration water kefir medium represents a demanding habitat. In this ecological niche only well adapted microorganisms which are fit to the consortium are able to grow and mutually provide essential nutrients. The synergism between main representatives of water kefir yeasts and lactobacilli was studied in a co-culture model system. Co-cultivation of yeasts and lactobacilli in water kefir medium significantly increased cell yield of all interaction partners, delineating the interaction of these water kefir isolates as mutualism. The support of Zygotorulaspora (Z.) florentina was due to the acidification of the medium by the lactobacilli, whereas lactobacilli are improved in growth by the disposal of essential nutrients produced by yeasts. The trophic interaction between Lactobacillus (Lb.) hordei and yeasts is constituted by the release of amino acids and Vitamin B₆ from yeasts, whereas Lb. nagelii is supported in growth by their production of amino acids. The interaction of Z. florentina and Lb. nagelii was further examined to reveal that co-cultivation induced the yeast to release arginine, which was essential for Lb. nagelii.     

Catalytic degradation of waste high-density polyethylene into fuel products using BaCO3 as a catalyst

Waste high-density polyethylene (HDPE) was degraded thermally and catalytically using BaCO₃ as a catalyst under different conditions of temperature, cat/pol ratio and time. The oil collected at optimum conditions (450 °C, 0.1 cat/pol ratio and 2 h reaction time) was fractionated at different temperatures and fuel property of the fractions and parent oil was evaluated by their physicochemical parameters for fuel tests. The results were compared with the standard values for gasoline, kerosene and diesel oil. Boiling point distribution (BPD) curves were plotted from the gas chromatographic study of the samples and compared with that of the standard gasoline, kerosene and diesel. The oil samples were analyzed using GC/MS in order to find out their composition. The physical parameters and the composition of the parent oil and its fractions support the resemblance of the samples with the standard fuel oils. The light fractions best match with gasoline, the middle fractions match with kerosene and the heavier fractions match with diesel oil in almost all of the characteristic properties.     

Characterization by Internal Photoemission Spectroscopy of Single-Crystal CVD Diamond Schottky Barrier Diodes

Internal photoemission spectroscopy measurements have been performed to study the electrical characteristics of Schottky diodes on boron-doped single-crystalline chemical vapor deposited (SC-CVD) diamond. These measurements were compared with current–voltage (I–V) and current–temperature (I–T) measurements. Schottky contact barrier heights and ideality factors have been measured on Schottky contacts formed on four samples with Au, Ni, and Al contact metallizations. I–V and I–T measurements were performed in the temperature range from 300 K to 500 K. The internal photoemission method, which is less influenced by local variations in the Schottky barrier height than the other two methods, yielded the highest values of Schottky barrier heights to p-type material: Φ_B = 1.78 eV to 2.10 eV, depending on the choice of contact metal and sample boron concentration.     

Experimental gallium nitride microwave Doherty amplifier

The combination of gallium nitride (GaN) device technology with the now well established efficiency enhancing Doherty power amplifier (PA) architecture is presented for the first time. The experimental structure exhibits a power density of approximately 1 W/mm and linearity that remains comparable to that observed in other GaAs structures, demonstrating that GaN can be highly effective when used within this type of PA architecture.     

Assessment of lower urinary tract functional deficit in rats with contusive spinal cord injury

Traumatic spinal cord injury (SCI) produces lower urinary tract (LUT) dysfunction that has been studied in surgical transection models. Our aim was to assess LUT functional deficit in a clinically relevant model of incomplete SCI to investigate how partial preservation of supraspinal connections might affect LUT dysfunction. Standardized weight-drop contusion (10 g x 2.5 cm) or complete transection, was produced at T8 in female Sprague-Dawley rats. Behavioral tests were used to assess hind limb sensorimotor function at Day 1 after surgery and weekly thereafter. The urometric experiments were conducted on groups (n = 7) of uninjured rats and on injured rats during Weeks 1 and 2 after SCI (before and after spontaneous voiding was established) as well as Week 2 after a complete transection (n = 3). Under anesthesia, the bladder was continuously perfused with saline. Changes in bladder pressure and external urethral sphincter (EUS) electrical activity were monitored. The bladder was then dissected and weighed and both the bladder and spinal cord were fixed for pathoanatomical analyses. Our results indicate that several aspects of LUT dysfunction after contusive SCI were similar to transection, e.g., reduction of voiding efficiency (approximately 5% of normal value), decrease in inter-contraction interval (47%), increase in bladder capacity (8-fold), and weight (4.6-fold). One aspect appeared different from transection--partial recovery from acute bladder/sphincter dyssynergia. Because the coordination of bladder and EUS function is mediated by brainstem pathways, partial recovery of synergy after SCI was likely due to sparing of some relevant bulbospinal projections as was confirmed by retrograde transneuronal viral tracing.     

以太网技术演变推动交换机大规模升级

推动对经济型高密度千兆以太网交换机需求不断增长的因素有多方面,如从快速以太网到千兆以太网标准的演进、新的高带宽应用,以及稳步上升的网络业务交易规模及数量。本文将对推动千兆以太网交换机密度和性能提高的应用及趋势作一个全面的评述。     

Influence of Interferon-Alpha Combined with Chemo (Radio) Therapy on Immunological Parameters in Pancreatic Adenocarcinoma

Prognosis of patients with carcinoma of the exocrine pancreas is particularly poor. A combination of chemotherapy with immunotherapy could be an option for treatment of pancreatic cancer. The aim of this study was to perform an immunomonitoring of 17 patients with pancreatic cancer from the CapRI-2 study, and tumor-bearing mice treated with combination of chemo (radio) therapies with interferon-2α. Low doses of interferon-2α led to a decrease in total leukocyte and an increase in monocyte counts. Furthermore, we observed a positive effect of interferon-2α therapy on the dendritic cells and NK (natural killer) cell activation immediately after the first injection. In addition, we recorded an increased amount of interferon-γ and IL-10 in the serum following the interferon-2α therapy. These data clearly demonstrate that pancreatic carcinoma patients also show an immunomodulatory response to interferon-2α therapy. Analysis of immunosuppressive cells in the Panc02 orthotopic mouse model of pancreatic cancer revealed an accumulation of the myeloid-derived suppressor cells in spleens and tumors of the mice treated with interferon-2α and 5-fluorouracil. The direct effect of the drugs on myeloid-derived suppressor cells was also registered in vitro. These data expose the importance of immunosuppressive mechanisms induced by combined chemo-immunotherapy.