Synthesis of eight-arm polystyrene by atom transfer radical polymerization

A new initiator for atom transfer radical polymerization (ATRP), (Cl2HCCOOCH2)(4)C(TDCAP) was designed and successfully synthesized. The initiator was,used to initiate,the polymerization of styrene via ATRP to method yield an eight-arm polystyrene with functional end-group chlorides. The different polymers could be prepared via ATRP of different monomers at 130 degrees C using TDCAP/CuCl/bPy as the initiating system. The initiator and eight-armed polymer were characterized by means of H-1 NMR, FTIR and GPC.

Maximins S, a novel group of antimicrobial peptides from toad Bombina maxima

Amphibian skin secretions are rich in antimicrobial peptides acting as important components of innate defense system against invading microorganisms. A novel type of peptide, designated as maximin S, was deduced by random sequencing of 793 clones from a constructed Bombina maxima skin cDNA library. The putative primary structures of maximin S peptides can be grouped into five species, in which maximin S I has 14 amino acid residues and the rest of maximin S peptides (S2-S5) all have 18 amino acid residues. Unlike most of the amphibian antimicrobial peptides so far identified, the newly characterized four maximin S precursors are composed of maximin S I and different combinations of tandem repeated maximin S2-S5 linked by internal peptides. Except maximin S I, the predicted secondary structures of maximin S2-S5 show a similar amphipathic alpha-helical structure. MALDI-TOF mass spectrometry analysis of partially isolated skin secretions of the toad indicates that most of the deduced maximin S peptides are expressed. Two deduced maximin S peptides (S1, S4) were synthesized and their antimicrobial activities were tested. Maximin S4 only had an antibiotic activity against mycoplasma and had no antibacterial or antifungal activity toward tested strains. Maximin S1 had no activity under the same conditions. (C) 2004 Elsevier Inc. All rights reserved.

A unique group of inactive serine protease homologues from snake venom

A number of inactive serine protease homologues (SPHs), which have poorly understood functions, have been identified in invertebrates and vertebrates. Recently, several SPH transcripts have been reported from snake venom glands, which provide potential ne

Maintenance of Multifemale Social Organization in a Group of Nomascus concolor at Wuliang Mountain, Yunnan, China

Many short-term studies have reported groups of black crested gibbons containing >= 2 adult females (Nomascus concolor). We report the stability of multifemale groups in this species over a period of 6 yr. Our focal group and 2 neighboring groups included 2 breeding females between March 2003 and June 2009. We also habituated 1 multifemale group to observers and present detailed information concerning their social relationships over a 9-mo observation period. We investigated interindividual distances and agonistic behavior among the 5 group members. The spatial relationship between the 3 adult members (1 male, 2 females) formed an equilateral triangle. A subadult male was peripheral to the focal group, while a juvenile male maintained a closer spatial relationship with the adult members. We observed little agonistic behavior among the adult members. The close spatial relationship and lack of high rates of agonistic behavior among females suggest that the benefits of living in a multifemale group were equal to or greater than the costs for both females, given their ecological and social circumstances. The focal group occupied a large home range that was likely to provide sufficient food sources for the 2 females and their offspring. Between March 2003 and June 2009, 1 adult female gave 2 births and the other one gave 1 birth. All individuals in the focal group survived to June 2009. A long-term comparative study focused on females living in multifemale groups and females living in pair-living groups would provide insight into understanding the evolutionary mechanisms of the social system in gibbons.

Molecular phylogeny of the yuhinas (Sylviidae : Yuhina): a paraphyletic group of babblers including Zosterops and Philippine Stachyris

Mitochondrial sequences (2,379 bp) from cytochrome b, ND3, 12s and 16s rRNA were analyzed in order to reconstruct the phylogenetic relationships within the yuhinas (Yuhina), including the chestnut-faced babbler Stachyris whiteheadi which is endemic to the

Differentiate performance of eight filter media in vertical flow constructed wetland: Removal of organic matter, nitrogen and phosphorus

A comparative study was conducted to reveal the differentiate effects of eight different filter media including gravel, zeolites, anthracite, shale, vermiculite, ceramic filter media, blast furnace steel slag and round ceramsite. The study mainly related to the eight different filter media's removal performances of organic matter, nitrogen and phosphorus in the vertical flow constructed wetland simulated system, which treating wastewater at hydraulic loading rate of 1000-2500 mm/d. The results indicated that the removal effects were closely related to the physical and chemical properties of medium materials. Anthracite-filled system had the highest removal rate for the total organic carbon (TOC), up to 70%, and the removal rates of other systems ranged from 20% to 30%. As for the five-day biochemical oxygen demand (BOD5), anthracite-filled and steel slag-filled systems had the highest removal rates, also up to 70%, as well as other systems all exceeded 50%. At the same time, for the total nitrogen (TN) and NH4(+)-N, the zeolites-filled and ceramic-filled systems had the best performances with the removal rates of more than 70%, the other way round, the removal rates of other systems were only about 20%. The distinguishable effects were also observed in removal performances of total phosphorus (TP) and total dissoluble phosphorus (TDP). The removal rates of TP and TDP in steel slag-filled systems were more than 90%, a much higher value, followed by that of the anthracite-filled system, more than 60%, but those of other systems being the less. Our study provided a potential mechanism to optimize the filter media design for the vertical flow constructed wetlands.

Sequence analysis of cytochrome b gene indicates that East Asian group of cyprinid subfamily Leuciscinae (Teleostei : Cyprinidae) evolved independently

The sequences of mitochondrial cytochrome b gene of cyprinid subfamily Leuciscinae are analyzed. Phylogenetic trees generated with methods of neighbor-joining, maximum likelihood and maximum parsimony with Phenacogrammus as an outgroup indicate that Leuciscinae is not a monophyletic group but includes two discrete subgroups. The East Asian group of the subfamily Leuciscinae, including the genera Ctenopharyngodon, Elopichthys, Luciobrama, Mylopharyngodon, Ochetobius, and Squaliobarbus, is close to Aristichthys and Hypophthalmichthys, and they form a monophyletic group which is distant from the leuciscine genera in Europe, Siberia and North America, such as Phoxinus, Leuciscus, Abramis, Rutilus, Chondrostoma, Alburnus, Opsopoedus, Lythrurus, and Pimephales. Our study suggests that the diversified East Asian group of the subfamily Leuciscinae should have an independent origination.