bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Substance Flow Analysis as a Valuable Risk Evaluation Tool – A Case Study for Brominated Flame Retardants as an Example of Potential Endocrine Disrupters
Authors: Morf Leo S. , Buser Andreas M. , Taverna Ruedi , Bader Hans-Peter , Scheidegger Ruth
Published: June 2008

Most studies of potentially hazardous substances focus on aspects of their occurrence and fate in the environment (monitoring and modelling studies) to estimate the environmental impact and the potential exposure of humans. In order to evaluate emission sources, to recognise environmental
impacts at an early stage, and to take efficient legislative or technical measures, it is essential to know their behaviour in the anthroposphere as a function of time. So far, only very few investigations of this type exist for chemicals. In regular risk assessments, only rather limited knowledge
is available concerning the behaviour of chemicals in the anthroposphere (production data, substance quantities in products, recycling rates, emissions occurring during use, etc.) or their lifecycle, and no information at all about their behaviour as a function of time. For this reason,
it is these aspects that were investigated in a case study within the framework of the national research programme NRP50 for selected brominated flame retardants with endocrine-disrupting potential (pentabromodiphenyl ether, hexabromocyclododecane) or the potential to degrade to such substances
(decabromodiphenyl ether). A dynamic substance flow analysis (SFA) model was performed for Switzerland for the time period 1980–2020. In this review paper (a) we present a summary of typical results (system overview, consumption trends/application patterns, anthropogenic stocks and their
changes, emission trends including major sources and environmental fate), (b) we summarize the effectiveness of recent risk-reduction measures in Switzerland and (c) we indicate serious remaining data gaps and recommend further important measures for risk reduction. For the future, we suggest
improving the knowledge of the lifecycle of chemicals such as brominated flame retardants by applying SFA as a suitable tool to weight the effect of substance flows with respect to environmental emissions, and to serve as the basis for planning actions and measures to reduce such emissions.
This is in line with one major conclusion of the NRP50 consensus platform 'Brominated Flame Retardants'.
Blockade of Atopic Dermatitis-Like Skin Lesions by DA-9102, a Natural Medicine Isolated from Actinidia arguta, in the Mg-Deficiency Induced Dermatitis Model of Hairless Rats
Authors: Choi Jeong June , Park Bokyoung , Kim Dong Hee , Pyo Myoung-Yun , Choi Sangzin , Son Miwon , Jin Mirim
Published: June 2008

DA-9102 isolated from Actinidia arguta is a candidate of natural medicine currently under Phase II clinical trial for atopic dermatitis in Korea. In this study, spontaneous dermatitis was induced by magnesium deficiency in hairless rats and this system was applied to assess the suppressive effects of DA-9102 on atopic dermatitis-like skin disease. Oral administration of DA-9102 at a dose of 100 mg/kg for 16 days substantially suppressed the occurrence of spontaneous dermatitis. Eczematous skin lesions, water loss and scratching behavior were significantly decreased by DA-9102 in a dose-dependent manner. Infiltration of inflammatory cells into the skin and pathologic remodeling of the epidermis and dermis were much less than the Mg-def. group. Results from flow cytometry analysis of peripheral blood mononuclear cells indicated that DA-9102 suppressed activation of leukocytes. The decrease in the number of CD45RA+ cells was accompanied by a lower level of IgE in DA-9102 treated rats, and the reduction in the number of CD11b+ cells by DA-9102 in both periphery and skin was significant. Further, DA-9102 not only suppressed the mRNA expression of TH2 cytokines including IL-4 and IL-10 in the lymph node but it also decreased the levels of inflammatory mediators such as nitric oxide and leukotriene B4 (LTB4) in the serum. Taken together, these results suggest that DA-9102 is an orally applicable potent immune modulator capable of controlling the occurrence of atopic dermatitis-like skin disease.
Herbogenomics: From Traditional Chinese Medicine to Novel Therapeutics
Authors: Kang Y. James
Published: June 2008

Traditional Chinese medicine (TCM) has a long history of development and application and has demonstrated on evidence basis its efficacy in the treatment of many diseases affecting multiple organ systems. In particular, TCM is effective in the prevention and treatment of chronic diseases and metabolic syndromes. However, the value of TCM has not been fully recognized worldwide due to the lack of definitive information of active ingredients in almost any TCM preparation. Novel functional genomics and proteomics approaches provide alternate perspectives on the mechanism of action of TCM. The target molecules on which TCM either activates or inactivates can be identified by functional genomics and proteomics, thus the affected critical signaling pathway cascades leading to effective recovery of chronic diseases can be studied. Several TCM preparations have been available for the treatment of liver fibrosis and cirrhosis, even advanced liver cirrhosis that has been shown to be irreversible and has no US-FDA approved therapy. In the TCM-treated livers with fibrosis and cirrhosis, some critical molecules that are significantly involved in the recovery can be identified through functional genomics and proteomics studies. These molecules become novel targets for drug discovery and development and candidates for the development of gene therapy. Gene therapy developed based on this strategy for the treatment of advanced liver fibrosis and cirrhosis in animal models has obtained promising results. This process thus establishes a herbogenomics approach to understand mechanisms of action of TCM and to identify effective molecular targets for the discovery and development of novel therapeutics.
MRP (ABCC) Transporters-Mediated Efflux of Anti-HIV Drugs, Saquinavir and Zidovudine, from Human Endothelial Cells
Authors: Eilers Mark , Roy Upal , Mondal Debasis
Published: June 2008

The constituents of highly active anti-retroviral therapy (HAART) include HIV-1 protease inhibitors (HPIs) and nucleoside reverse transcriptase inhibitors (NRTIs). Endothelial cell (EC) barriers, especially the blood-brain-barrier (BBB) suppresses the entry of HAART drugs to subendothelial HIV-1 reservoirs. The ATP binding cassette (ABC) transporter family members, multidrug resistant-1 (MDR-1) and multidrug resistance-associated proteins (MRPs) can efflux both HPIs and NRTIs from intracellular compartments. Using brain derived ECs from non-human sources, previous studies suggested a dominant role for MDR-1 in HAART efflux from the BBB. However, due to species variations in ABC-transporter expression, drug-efflux functions using human brain ECs need to be investigated. Furthermore, roles of ABC-transporters in drug-efflux from systemic EC barriers need to be studied. We monitored the expression of ABC-transporters in primary human ECs obtained from brain (HBMVECs), aorta (HAECs), pulmonary-artery (HPAECs), dermal-microvessel (HDMVECs) and umbilical vein (HUVECs). Gene expression for MDR-1 and MRPs (MRP-1 to MRP-5) were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR). Drug efflux functions were determined by calcein retention assays. Intracellular accumulation of both3H-saqui-navir (an HPI) and3H-zidovudine (an NRTI) were also monitored in HAECs and HBMVECs. Both assays were carried out in presence of verapamil (20–60 μM) or MK-571 (12.5–50 μM) inhibitors of MDR-1 and MRPs, respectively in presence of verapamil or MK-571. The HBMVECs expressed higher levels of MRPs than MDR-1 and only MK-571 significantly ( P < 0.01) suppressed calcein efflux from these cells. However, both HAECs and HPAECs showed MDR-1 and MRP expression and calcein efflux was inhibited by both verapamil and MK-571. Both inhibitors suppressed3H-saqubinavir efflux from HAECs, but only MK-571 suppressed saquinavir efflux from HBMVECs. In both ECs,3H-zidovudine efflux was only suppressed by MK-571. Thus, primary human ECs, especially brain derived ECs, predominantly express MRPs and their specific inhibition may enhance HAART efficacy in subendothelial HIV-1 reservoirs.
Establishing the Use of Melatonin as an Adjuvant Therapeutic Against Paraquat-Induced Lung Toxicity in Rats
Authors: Göcgeldi Ercan , Uysal Bülent , Korkmaz Ahmet , Ogur Recai , Reiter Russel J. , Kurt Bülent , Öter Sükrü , Topal Turgut , Hasde Metin
Published: June 2008

It is well known that the intake of paraquat (PQ) causes severe tissue injury leading to numerous fatalities. Considering that the main target for PQ toxicity is the lung and involves the production of reactive oxygen and nitrogen species, transcription factors and inflammatory cytokines, it may be hypothesized that the combination of a potent antiinflammatory and antioxidant agent may counteract more of PQ’s effects than an antiinflammatory agent alone. For this purpose, combination of dexamethasone (Dex) and melatonin (Mel) was compared with Dex alone. A total of 40 male Wistar albino rats were divided into four groups as control, PQ, Dex only, and Dex plus Mel. The animals were given intraperitoneally a toxic dose of 19 mg/kg PQ dissolved in 1 ml saline. Control animals were injected with the same amount of saline only. A dose of 1 mg/kg Dex was administered 2 hrs after PQ administration. In the combination treatment group, 20 mg/kg Mel was given with Dex. All drugs were given every 12 hrs for a total of six doses. Five animals in PQ group and three animals in Dex only group died by the end of the study. No deaths occurred in the Dex+Mel group. Dex exerted improvements in several oxidative and antioxidative parameters. However, combination treatment provided beneficial effects against PQ toxicity far greater than Dex alone. This difference was also apparent when tissues were histologically compared. In conclusion, Mel exhibited strong additive beneficial effects with Dex and can be considered as a safe treatment modality against PQ toxicity.
Happiness and the Good Life
Authors: O'Neill John
Published: June 2008

Holland argues that environmental deliberation should return to classical questions about the nature of the good life, understood as the worthwhile life. Holland's proposal contrasts with the revived hedonist conception of the good life which has been influential on environmentalism. The concept of the worthwhile life needs to be carefully distinguished from those of the happy life and the dutiful life. Holland's account of the worthwhile life captures the narrative dimension of human well-being which is revealed but inadequately addressed by hedonic research. Environmental concerns are better understood from a non-hedonist perspective. An Aristotelian version of this perspective also offers the institutional focus which Holland suggests is required in environmental deliberation.
Do Meaningful Relationships with Nature Contribute to a Worthwhile Life?
Authors: Firth Dan
Published: June 2008

This paper argues that a worthwhile life is one in which the meaningful relationships existing in nature are recognised and respected. A meaningful relationship occurs when the interactions between two entities have significance in their past history and its anticipated continuation. The form in which the history of both the human and the non-human is related is narrative. A life is enriched or impoverished by the subject's relationships to other people and nature, and as such is more or less worthwhile. The argument presented here shows how Alan Holland's approach to conservation decision making can be extended to have relevance to individual lives, and that a strong ethical position can be developed from this insight.
Environmental Values and Human Purposes
Authors: Benton Ted
Published: June 2008

Some writings by Alan Holland provide the starting point for an exploration of sources of environmental value in human social practices. It is argued that many practices both serve human purposes and also provide a setting for the emergence of environmental value. Such practices are ones in which activity is embedded in, and so both strongly constrained and enabled by, its conditions and media. Capitalist ‘modernisation’ has tended to erode these practices and associated values in favour of external purposes and instrumental values, especially in the farmed countryside. In the face of this, and partly on grounds of social justice, a re-valuation of urban open spaces is advocated.
MEL‐type Pure‐Silica Zeolite Nanocrystals Prepared by an Evaporation‐Assisted Two‐Stage Synthesis Method as Ultra‐Low‐k Materials
Authors: Liu Yan , Sun Minwei , Lew Christopher M. , Wang Junlan , Yan Yushan
Published: June 2008

A MEL‐type pure‐silica zeolite (PSZ), prepared by spin‐on of nanoparticle suspensions, has been shown to be a promising ultra‐low‐dielectric‐constant (k) material because of its high mechanical strength, hydrophobicity, and chemical stability. In our previous works, a two‐stage synthesis method was used to synthesize a MEL‐zeolite nanoparticle suspension, in which both nanocrystal yield and particle size of the zeolite suspension increased with increasing synthesis time. For instance, at a crystal yield of 63%, the particle size is 80 nm, which has proved to be too large because it introduces a number of problems for the spin‐on films, including large surface roughness, surface striations, and large mesopores. In the current study, the two‐stage synthesis method is modified into an evaporation‐assisted two‐stage method by adding a solvent‐evaporation process between the two thermal‐treatment steps. The modified method can yield much smaller particle sizes (e.g., 14 vs. 80 nm) while maintaining the same nanocrystal yields as the two‐stage synthesis. Furthermore, the nanoparticle suspensions from the evaporation‐assisted two‐stage synthesis show a bimodal particle size distribution. The primary nanoparticles are around 14 nm in size and are stable in the final suspension with 60% solvent evaporation. The factors that affect nanocrystal synthesis are discussed, including the concentration, pH value, and viscosity. Spin‐on films prepared by using suspensions synthesized this way have no striations and improved elastic modulus (9.67 ± 1.48 GPa vs. 7.82 ± 1.30 GPa), as well as a similar k value (1.91 ± 0.09 vs. 1.89 ± 0.08) to the previous two‐stage synthesized films.
VEGF‐Functionalized Polyelectrolyte Multilayers as Proangiogenic Prosthetic Coatings
Authors: Müller Sabine , Koenig Géraldine , Charpiot Anne , Debry Christian , Voegel Jean‐Claude , Lavalle Philippe , Vautier Dominique
Published: June 2008

Stimulation of transprosthetic vascularization represents an interesting strategy in implantology to allow rapid tissue integration and finally to avoid prosthetic rejection. To achieve this goal, we modified the surface of porous titanium implants with polyelectrolyte multilayer (PEM) films functionalized with vascular endothelial growth factor (VEGF). Among the two PEM systems investigated, poly(L‐lysine)/poly(L‐glutamic acid) (PLL/PGA) and poly(allylamine hydrochloride)/poly(sodium 4‐styrenesulfonate) (PAH/PSS), the (PAH/PSS)4 architecture was selected to functionalize porous titanium, both for its high efficiency to adsorb VEGF and for its biocompatibility toward endothelial cells. In an original way, we unambiguously demonstrated that VEGF adsorbed on (PAH/PSS)4 maintains its bioactivity in vitro and stimulates endothelial cells proliferation. This effect was correlated with specific activation of intracellular signaling pathways induced by successive phosphorylation of the endothelial VEGF receptor VEGFR2 and mitogen‐activated protein kinases (MAPK) ERK1/2. By clearly demonstrating the proangiogenic activity of the VEGF‐PEM coating in vitro, the present study constitutes a first step toward in vivo application.
Thermally crosslinked anionic hydrogels composed of poly(vinyl alcohol) and poly(γ‐glutamic acid): Preparation, characterization, and drug permeation behavior
Authors: Lee Young‐Gi , Kang Hahk‐Soo , Kim Mi‐Soon , Son Tae‐Il
Published: June 2008

pH‐sensitive anionic hydrogels composed of poly(vinyl alcohol) (PVA) and poly(γ‐glutamic acid) (γ‐PGA) were prepared by the freeze drying method and thermally crosslinked to suppress hydrogel deformation in water. The physical properties, swelling, and drug‐diffusion behaviors were characterized for the hydrogels. In the equilibrium swelling study, PVA/γ‐PGA hydrogels shrunk in pH regions below the pKa (2.27) of γ‐PGA, whereas they swelled above the pKa. In the drug‐diffusion study, the drug permeation rates of the PVA/γ‐PGA hydrogels were directly proportional to their swelling behaviors. The cytocompatibility test showed no cytotoxicity of the PVA/γ‐PGA hydrogels for the 3T3 fibroblast cell lines. The results of these studies suggest that hydrogels prepared from PVA and γ‐PGA could be used as orally administrable drug‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Green composites reinforced with hemp nanocrystals in plasticized starch
Authors: Cao Xiaodong , Chen Yun , Chang Peter R. , Stumborg Mark , Huneault Michel A.
Published: June 2008

New nanocomposite films were prepared from a mixed suspension of hemp cellulose nanocrystals (HCNs) and thermoplastic starch, or plasticized starch (PS), by the casting and evaporating method. The morphology, thermal behavior, mechanical properties, and water sensitivity of the films were investigated by means of scanning electron microscopy, wide‐angle X‐ray diffraction, differential scanning calorimetry, tensile testing, contact angle measurements, and water absorption. The results indicate that the cellulose nanocrystals dispersed in the PS matrix homogeneously and resulted in an increase in the glass‐transition temperature ascribed to the fact that the flexibility of the starch molecular chains in the starch‐rich phase was reduced because of the strong intermolecular interactions between the starch and stiff HCNs. The films exhibited significant increases in the tensile strength and Young's modulus, from 3.9 to 11.5 MPa and from 31.9 to 823.9 MPa, respectively, with increasing HCN content from 0 to 30 wt %. In addition to the improvement in mechanical properties, the incorporation of HCNs into the PS matrix also led to a decrease in the water sensitivity of the final composite materials. Therefore, the HCNs played an important role in improving the mechanical properties and water resistance of the starch‐based material. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Thermal and rheological properties of poly(vinyl alcohol) and water‐soluble chitosan hydrogels prepared by a combination of γ‐ray irradiation and freeze thawing
Authors: Yang Xiaomin , Zhu Zhiyong , Liu Qi , Chen Xiliang
Published: June 2008

Poly(vinyl alcohol) (PVA)/water‐soluble chitosan (ws‐chitosan) hydrogels were prepared by a combination of γ‐irradiation and freeze thawing. The thermal and rheological properties of these hydrogels were compared with those of hydrogels prepared by pure irradiation and pure freeze thawing. Irradiation reduced the crystallinity of PVA, whereas freeze thawing increased it. Hydrogels made by freeze thawing followed by irradiation had higher degrees of crystallinity and higher melting temperatures than those made by irradiation followed by freeze thawing. ws‐Chitosan disrupted the ordered association of PVA molecules and decreased the thermal stability of both physical blends and hydrogels. All the hydrogels showed shear‐thinning behavior in the frequency range of 0.2–100 rad/s. Hydrogels made by freeze thawing dissolved into sol solutions at about 80°C, whereas those made by irradiation showed no temperature dependence up to 100°C. The chemical crosslinking density of the hydrogels made by irradiation followed by freeze thawing was much greater than that of hydrogels made by freeze thawing followed by irradiation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
A fractal model of tensile fracture surfaces for particulate‐filled polymer composites
Authors: Liang J. Z. , Wu C. B.
Published: June 2008

Tensile mechanical properties are important for the characterization of the utilization performances of materials. Inorganic particles are usually used to reinforce and toughen resins and to reduce costs in the polymer industry. It is, therefore, very important to quantitatively appraise the break way and mechanisms and the reinforcing or toughening effect of the fracture surface of tensile specimens. A tensile fracture surface fractal model of particulate‐filled polymer composites on the basis of fractal theory is established and a corresponding equation for the tensile fracture surface fractal dimension is proposed in this article. Tensile fracture surface fractal dimensions of particulate‐filled polymer composites at filler volume fractions of 2–30% were estimated by means of this equation, and the calculations were compared with the measuring values of calcium carbonate filled acrylonitrile–butadiene–styrene (ABS) resin and titanium dioxide filled ABS resin composites reported in the literature. The results show that the theoretic estimations and the measuring values were roughly close to each other. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Characterization of high‐performance exfoliated natural rubber/organoclay nanocomposites
Authors: Li Peiyao , Wang Li , Song Guojun , Yin Lanlan , Qi Feng , Sun Liangdong
Published: June 2008

The exfoliated natural rubber (NR)/organoclay nanocomposites were successfully prepared with an optimal organoclay by direction blending. The optimal‐type organoclay was chosen by characterization of XRD and the mechanical properties characterization of the NR/organoclay composites from three kinds of organoclay. The observation of transmission electron microscopy (TEM) revealed well‐ordered exfoliated single layers of organoclay. The results of mechanical properties measurement showed that the tensile strength, tensile modulus, and tear strength were improved remarkably with small amounts of organoclay, whose contents were below 5.0 phr. For example, incorporating with 3.0 phr organoclay, the tensile strength and tear strength of nanocomposite were 24.7 MPa and 34.7 kN/m, respectively, which increased ∼ 89.5% and 61.6%. Furthermore, the results of coreinforcement system with high performance indicated a promising application of the organoclay and nanocomposites. The values of the weight‐swelling ratio of nanocomposites decreased much, which meant the oil resistance of nanocomposites enhanced. The TGA results indicated that the thermal stability of nanocomposites was improved. The reduction of oxygen permeability implied the gas‐barrier properties of the nanocomposites improved. Furthermore, the mechanism of barrier of clay layers was discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and simple method of estimating macroporosity of methyl methacrylate–divinylbenzene copolymer beads
Authors: Malik Muhammad Arif , Ali Syed Wasim
Published: June 2008

Macroporous methyl methacrylate–divinylbenzene copolymer beads having diameter ∼ 300 μm were synthesized by free radical suspension copolymerization. The macroporosity was generated by diluting the monomers with inert organic liquid diluents. The macroporosity was varied in the range of ∼0.1 to ∼ 1.0 mL/g by varying a number of porosity controlling factors, such as the diluents, solvent to nonsolvent mixing ratios when employing a mixture of the two diluents, degree of dilution, and crosslinkage. Increase in pore volume from 0.1 to 0.45 mL/g resulted in a sharp increase in mesopores having diameters in the range of 3–20 nm whereas the macropores remained negligible when compared with mesopores. Increase in pore volume from 0.45 to 1 mL/g resulted in a sharp increase in macropores, whereas mesopores having diameters in the range of 3–20 nm remained almost constant. The mesopores having diameters in the range of 20–50 nm showed an increase with the increase in pore volume throughout the whole range of pore volume studied. Macroporosity characteristics, i.e., pore volume (Vm), surface area (SA), and pore size distributions were evaluated by mercury penetration method. Statistical analysis of the data obtained in the present study shows that the macroporosity characteristics can be estimated with a reasonable accuracy from the pore volumes, which in turn are determined from the densities of the copolymers. These results are explained on the basis of pore formation mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Modeling solubility parameters and permeation data of organic solvents versus butyl gloves from four manufacturers
Authors: Evans Katherine M. , Guo Wumin , Hardy James
Published: June 2008

A model based on the combination of Hansen solubility parameter theory and Flory‐Rehner polymer solution theory was used to determine the solubility parameters of butyl glove material provided by several different manufacturers using a nonlinear least‐square regression. To evaluate the validity of this model, weight gain data were collected for 26 solvents versus butyl gloves from four different vendors. Good correlation was found with R2 ranging from 0.858 to 0.961, which was attributed to extended weight gain testing and weight gain calculations based on glove sample weight after immersion and postdrying. Steady‐state permeation rates (molar steady‐state permeation rates), breakthrough times, and lag times for the butyl glove samples against solvents were determined and correlated to solvent‐polymer interactive term χϕp2. A high level of correlation was observed for all glove materials. Correlation was also made with permeation data collected from three of the four glove materials, and a high degree of correlation was found with R2 ranging from 0.8644 to 0.9369 for steady‐state permeation rates (molar steady‐state permeation rates), breakthrough times, and lag times. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Radical polymerization behavior of dimethyl vinylphosphonate: Homopolymerization and copolymerization with trimethoxyvinylsilane
Authors: Sato Tsuneyuki , Hasegawa Makoto , Seno Makiko , Hirano Tomohiro
Published: June 2008

Dialkyl vinylphosphonates such as dimethyl vinylphosphonate (DMVP) and diethyl vinylphosphonate were quantitatively polymerized with dicumyl peroxide (DCPO) at 130°C in bulk. The polymerization of DMVP with DCPO was kinetically studied in bulk by fourier transform near‐infrared spectroscopy (FTNIR) and electron spin resonance (ESR) spectroscopy. The initial polymerization rate (Rp) was given by Rp = k[DCPO]0.5[DMVP]1.0 at 110°C, being the same as that of the conventional radical polymerization involving bimolecular termination. The overall activation energy of the polymerization was estimated to be 26.2 kcal/mol. The polymerization system involved ESR‐observable propagating polymer radicals under the practical polymerization conditions. ESR‐determined rate constants of propagation (kp) and termination (kt) were kp = 19 L/mol s and kt = 5.8 × 103 L/mol s at 110°C, respectively. The molecular weight of the resultant poly(DMVP)s was low (Mn = 3.4 − 3.5 × 103), because of the high chain transfer constant (Cm = 3.9 × 10−2 at 110°C) to the monomer. DMVP (M1) showed a considerably high reactivity in the radical copolymerization with trimethoxyvinylsilane (TMVS) (M2) at 110°C in bulk, giving an inorganic component‐containing functional copolymer with potential flame‐retardant properties; r1 = 1.6 and r2 = 0. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Structural, Functional and Calorimetric Investigation of MosA, a Dihydrodipicolinate Synthase from Sinorhizobium meliloti L5–30, does not Support Involvement in Rhizopine Biosynthesis
Authors: Phenix Christopher P. , Nienaber Kurt , Tam Pui Hang , Delbaere Louis T. J. , Palmer David R. J.
Published: June 2008

MosA is an enzyme from Sinorhizobium meliloti L5–30, a beneficial soil bacterium that forms a symbiotic relationship with leguminous plants. MosA was proposed to catalyze the conversion of scyllo‐inosamine to 3‐O‐methyl‐scyllo‐inosamine (compounds known as rhizopines), despite the MosA sequence showing a strong resemblance to dihydrodipicolinate synthase (DHDPS) sequences rather than to methyltransferases. Our laboratory has already shown that MosA is an efficient catalyst of the DHDPS reaction. Here we report the structure of MosA, solved to 1.95 Å resolution, which resembles previously reported DHDPS structures. In this structure Lys161 forms a Schiff base adduct with pyruvate, consistent with the DHDPS mechanism. We have synthesized both known rhizopines and investigated their ability to interact with MosA in the presence and absence of methyl donors. No MosA‐catalyzed methyltransferase activity is observed in the presence of scyllo‐inosamine and S‐adenosylmethionine (SAM). 2‐Oxobutyrate can form a Schiff base with MosA, acting as a competitive inhibitor of MosA‐catalyzed dihydrodipicolinate synthesis. It can be trapped on the enzyme by reaction with sodium borohydride, but does not act as a methyl donor. The presence of rhizopines does not affect the kinetics of dihydrodipicolinate synthesis. Isothermal titration calorimetry (ITC) shows no apparent interaction of MosA with rhizopines and SAM. Similar experiments with pyruvate as titrant demonstrate that the reversible Schiff base formation is largely entropically driven. This is the first use of ITC to study Schiff base formation between an enzyme and its substrate.
Layer‐By‐Layer Assembly of Viral Nanoparticles and Polyelectrolytes: The Film Architecture is Different for Spheres Versus Rods
Authors: Steinmetz Nicole F. , Findlay Kim C. , Noel Timothy R. , Parker Roger , Lomonossoff George P. , Evans David J.
Published: June 2008

The development of tuneable thin film assemblies that contain (bio)nanoparticles is an emerging field in nanobiosciences/nanotechnology. Our research focuses on the utilisation of viral nanoparticles (VNPs) as tools and building blocks for materials science. In previous reports we studied multilayered arrays of chemically modified cowpea mosaic virus (CPMV) particles and linker molecules. To extend these studies and to gain more insights into the architecture of the arrays, we report here on the construction of multilayered assemblies of native plant viral particles and polyelectrolytes. We specifically addressed the question of whether the shape of the VNPs influences the overall structures of the arrays. To study this, we have chosen two particles with similar surface properties but different shapes: CPMV was used as a sphere‐like VNP, and tobacco mosaic virus (TMV) served as a rod‐shaped VNP. The multilayers were self‐assembled on solid supports through electrostatic interactions. Multilayer build‐up was followed by quartz crystal microbalance with dissipation monitoring and UV/Vis spectroscopy. Scanning electron microscopy was used to characterize the topologies of the thin films. Our studies show that shape indeed matters. Incorporation of CPMV in alternating arrays of VNPs and polyelectrolytes is demonstrated; in stark contrast, TMV particles were found to be excluded from the arrays, and floated atop the architecture in an ordered structure.
Stereospecific effects of benzo[d]isothiazolyloxypropanolamine derivatives at β‐adrenoceptors: Synthesis, chiral resolution, and biological activity in vitro
Authors: Comini Mara , Pozzoli Cristina , Incerti Matteo , Rossi Daniela , Collina Simona , Azzolina Ornella , Di Vittorio Elena , Morini Giovanni , Poli Enzo
Published: June 2008

We performed the asymmetric synthesis of four enantiopure benzo[d] isothiazo‐3‐or 5‐yloxypropanolamine derivatives, previously described as competitive antagonists at β‐adrenoceptors. The chemical characterization of each enantiomer was accomplished by1H NMR and HPLC/DAD/CD. The direct chromatographic separation of the enantiomersviachiral HPLC was investigated. The best resolutions were achieved using cellulose tris (3,5‐dimethylphenyl carbamate) (Chiralcel OD‐H) and amylose tris (3,5‐dimethylphenyl carbamate) (Chiralpak AD). The enantiomers obtained had enantiomeric purities suitable for biological assays. Tested in isolated rat cardiac and intestinal tissues to evaluate their effects at β1‐ and β3‐adrenoceptors, the (S)‐enantiomers revealed a higher degree of antagonism than (R)‐enantiomers at both subtypes, even though their activity was greater at the cardiac β1‐subtype. The potent and cardiospecific antagonistic effect exerted by the compounds tested suggests that the benzisothiazole moiety could be an interesting scaffold for discovering new chiral β‐blocking drugs. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Synaptic circuits of the Drosophila optic lobe: The input terminals to the medulla
Authors: Takemura Shin‐Ya , Lu Zhiyuan , Meinertzhagen Ian A.
Published: June 2008

Understanding the visual pathways of the fly's compound eye has been blocked for decades at the second optic neuropil, the medulla, a two‐part relay comprising 10 strata (M1–M10), and the largest neuropil in the fly's brain. Based on the modularity of its composition, and two previous reports, on Golgi‐impregnated cell types (Fischbach and Dittrich, Cell Tissue Res.,1989; 258:441–475) and their synaptic circuits in the first neuropil, the lamina, we used serial‐section electron microscopy to examine inputs to the distal strata M1–M6. We report the morphology of the reconstructed medulla terminals of five lamina cells, L1–L5, two photoreceptors, R7 and R8, and three neurons, medulla cell T1 and centrifugal cells C2 and C3. The morphology of these conforms closely to previous reports from Golgi impregnation. This fidelity provides assurance that our reconstructions are complete and accurate. Synapses of these terminals broadly localize to the terminal and provide contacts to unidentified targets, mostly medulla cells, as well as sites of connection between the terminals themselves. These reveal that R8 forms contacts upon R7 and thus between these two spectral inputs; that L3 provides input upon both pathways, adding an achromatic input; that the terminal of L5 reciprocally connects to that of L1, thus being synaptic in the medulla despite lacking synapses in the lamina; that the motion‐sensing input cells L1 and L2 lack direct interconnection but both receive input from C2 and C3, resembling lamina connections of these cells; and that, as in the lamina, T1 provides no output chemical synapses. J. Comp. Neurol. 509:493–513, 2008. © 2008 Wiley‐Liss, Inc.
Glial investment of the adult and developing antennal lobe of Drosophila
Authors: Oland Lynne A. , Biebelhausen John P. , Tolbert Leslie P.
Published: June 2008

In recent years the Drosophila olfactory system, with its unparalleled opportunities for genetic dissection of development and functional organization, has been used to study the development of central olfactory neurons and the molecular basis of olfactory coding. The results of these studies have been interpreted in the absence of a detailed understanding of the steps in maturation of glial cells in the antennal lobe. Here we present a high‐resolution study of the glia associated with olfactory glomeruli in adult and developing antennal lobes. The study provides a basis for comparison of findings in Drosophila with those in the moth Manduca sexta that indicate a critical role for glia in antennal lobe development. Using flies expressing GFP under a Nervana2 driver to visualize glia for confocal microscopy, and probing at higher resolution with the electron microscope, we find that glial development in Drosophila differs markedly from that in moths: glial cell bodies remain in a rind around the glomerular neuropil; glial processes ensheathe axon bundles in the nerve layer but likely contribute little to axonal sorting; their processes insinuate between glomeruli only very late and then form only a sparse, open network around each glomerulus; and glial processes invade the synaptic neuropil. Taking our results in the context of previous studies, we conclude that glial cells in the developing Drosophila antennal lobe are unlikely to play a strong role in either axonal sorting or glomerulus stabilization and that in the adult, glial processes do not electrically isolate glomeruli from their neighbors. J. Comp. Neurol. 509:526–550, 2008. © 2008 Wiley‐Liss, Inc.
Bone morphogenetic protein regulation of enteric neuronal phenotypic diversity: Relationship to timing of cell cycle exit
Authors: Chalazonitis Alcmène , Pham Tuan D. , Li Zhishan , Roman Daniel , Guha Udayan , Gomes William , Kan Lixin , Kessler John A. , Gershon Michael D.
Published: June 2008

The effects of bone morphogenetic protein (BMP) signaling on enteric neuron development were examined in transgenic mice overexpressing either the BMP inhibitor, noggin, or BMP4 under control of the neuron specific enolase (NSE) promoter. Noggin antagonism of BMP signaling increased total numbers of enteric neurons and those of subpopulations derived from precursors that exit the cell cycle early in neurogenesis (serotonin, calretinin, calbindin). In contrast, noggin overexpression decreased numbers of neurons derived from precursors that exit the cell cycle late (γ‐aminobutyric acid, tyrosine hydroxylase [TH], dopamine transporter, calcitonin gene‐related peptide, TrkC). The numbers of TH‐ and TrkC‐expressing neurons were increased by overexpression of BMP4. These observations are consistent with the idea that phenotypic expression in the enteric nervous system (ENS) is determined, in part, by the number of proliferative divisions neuronal precursors undergo before their terminal mitosis. BMP signaling may thus regulate enteric neuronal phenotypic diversity by promoting the exit of precursors from the cell cycle. BMP2 increased the numbers of TH‐ and TrkC‐expressing neurons developing in vitro from immunoselected enteric crest‐derived precursors; BMP signaling may thus also specify or promote the development of dopaminergic TrkC/NT‐3‐dependent neurons. The developmental defects in the ENS of noggin‐overexpressing mice caused a relatively mild disturbance of motility (irregular rapid transit and increased stool frequency, weight, and water content). Although the function of the gut thus displays a remarkable tolerance for ENS defects, subtle functional abnormalities in motility or secretion may arise when ENS defects short of aganglionosis occur during development. J. Comp. Neurol. 509:474–492, 2008. © 2008 Wiley‐Liss, Inc.
Discovery of textual knowledge flow based on the management of knowledge maps
Authors: Luo Xiangfeng , Hu Qingliang , Xu Weimin , Yu Zhian
Published: June 2008

Textual knowledge flow (TKF) provides an effective technique and theoretical support for the discovery and cooperation of knowledge innovation, intelligent browsing, and personalized recommendation in Web services and e‐Science Knowledge Grid. For the discovery of TKF, firstly knowledge map (KM) is proposed to represent the textual knowledge; then a hash algorithm is used to code KMs in order to form an Island which contains enormous KMs belonging to a domain. Under the control of the Island, C‐Location and R‐Location are introduced to manage those KMs belonging to an Island. KM‐Chord is proposed to manage the number of Islands, C‐Locations and R‐Locations in Web or a library. With the help of the management of KMs, similar relation and associated relation between KMs are found to build the semantic link network (SLN) between KMs. Based on the SLN and users' profile and input, similar or associated TKF with the user's different demands is activated. Experiments show that the proposed method can effectively discover TKF for Web services and e‐Science Knowledge Grid. Copyright © 2008 John Wiley & Sons, Ltd.
A service‐oriented business performance evaluation model and the performance‐aware service selection method
Authors: Liu Bo , Fan Yushun , Huang Shuangxi
Published: June 2008

In service‐oriented architecture, services and business processes are closely related and therefore the research on service‐oriented business process (SOBP) attracts the attention of academia as well as industry. Because of the loosely coupled, autonomic and dynamic nature of services, the operation and the performance evaluation of business process meet some challenges, such as the definition of the key performance indicators (KPIs) and the alignment of business performance and IT performance. In this paper, we address these challenges. First, the definition and the characteristics of an SOBP are presented with a motivating scenario. Then a service‐oriented business performance evaluation model is described, which integrates the performance of strategy layer, business process layer, business activity layer, service composition layer and IT infrastructure layer. The KPIs corresponding to each layer are also defined with their formal representations. The qualitative and quantitative performance analysis methods, based on the proposed model, are presented, respectively. Finally, the improved analytic hierarchy process is explicated to calculate the correlation between different KPIs and select the most suitable service. An online‐shopping example is taken to prove the soundness and the feasibility of the method. Copyright © 2008 John Wiley & Sons, Ltd.
A dynamic admission control scheme to manage contention on shared computing resources
Authors: Xavier Percival , Cai Wentong , Lee Bu‐Sung
Published: June 2008

A virtual organization is established when physical organizations collaborate to share their computing resources with the aim of serving each other when there is a likelihood of insufficient local resources during peak resource usage periods at any organization. Contention becomes a potential problem when a large number of requests, which can overwhelm the aggregate capacity of shared resources, are submitted from the participating organizations coincidentally at the same period. In particular, when a small number of requests that require large amounts of computing resources are admitted in place of a large number of requests that require less computing resources, the overall system performance, in terms of admission ratio, can deteriorate significantly. Hence, admission control is necessary to reduce resource oversubscription. Because domain‐shared computing resources are likely to be combined to form a large‐scale system, it is not possible to define a fixed admission policy solely based on the request's CPU and execution time requirements. In this paper, we introduce an admission control framework, based on a pricing model, for a multi‐domain‐shared computing infrastructure. The performance of the admission control framework is evaluated under different scenarios that contribute to the overall degree of competition for shared resources. The results are presented and analyzed in this paper. Copyright © 2008 John Wiley & Sons, Ltd.
Performance evaluation of virtual machine‐based Grid workflow system
Authors: Wang Lizhe , Kunze Marcel , Tao Jie
Published: June 2008

Grid computing has now become the de facto standard for distributed computing and provides huge computing resources for high‐performance scientific and engineering applications. Recent advantages of virtual computing technologies make it possible to efficiently employ computing resources on‐demand. Distributed virtual machines (VMs) can help to build scalable, manageable and efficient Grid infrastructures. This paper is engaged to organize compact muon solenoid applications in virtual data system workflows and execute them on VMs in computational Grids. The work is implemented on VMware VMs. Test results are discussed and the performance is evaluated with comparison of related work. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis, Characterization, and Magnetic Properties of a 1D Oxalate‐Bridged MnII Complex Consisting of 10‐Membered Ring Units
Authors: Li Wei , Jia Hong‐Peng , Ju Zhan‐Feng , Zhang Jie
Published: June 2008

Self‐assembly of the newly synthesized 2‐methyl‐4,6‐bis(4′‐pyridyl‐1′‐pyridinio)pyrimidine dichloride (MbppCl2) with MnCl2·4H2O and Na2C2O4 affords an unprecedented chain‐like oxalate‐bridged MnII polymer consisting of 10‐membered ring units, {[Mn3(OH)(H2O)2(Mbpp)(C2O4)3.5]·6.5H2O}n (1), which exhibits spin‐canted antiferromagnetism at low temperature.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Nafion–Zirconium Phosphate Nanocomposite Membranes with High Filler Loadings: Conductivity and Mechanical Properties
Authors: Casciola M. , Capitani D. , Comite A. , Donnadio A. , Frittella V. , Pica M. , Sganappa M. , Varzi A.
Published: June 2008

Zirconium phosphate (ZrP) was incorporated in preformed Nafion 117 membranes by exchange of the ionomer protons with zirconium cationic species and subsequent treatment with phosphoric acid. Reiteration of these treatments under the same reaction conditions allowed to obtain membranes with filler loading in the range of 20–40 wt.‐%. 31P MAS NMR investigations showed that the filler is mainly α‐ZrP and that the fraction of monohydrogen phosphate groups in the α‐type environment increases with the number of treatments. All membranes were characterised by stress–strain mechanical tests at room temperature and turned out to be stiffer than Nafion 117. Through‐plane conductivity determinations were carried out as a function of temperature and relative humidity (RH). At 100 °C and RH in the range of 30–90%, the composite membranes were less conductive than Nafion 117, and the higher the filler loading the larger the conductivity decrease occurring with decreasing RH. The conductivity of the composite membranes showed however better long‐term stability at high temperature and RH values. Moreover, the partial replacement of the phosphate groups of ZrP with sulphophenylphosphonate groups leads to a significant improvement of conductivity and stiffness with respect to both Nafion 117 and the parent composite membrane.
Ceramic‐based Anode Materials for Improved Redox Cycling of Solid Oxide Fuel Cells
Authors: Fu Q. X. , Tietz F.
Published: June 2008

In order to improve the reliability of anode‐supported solid oxide fuel cells (SOFCs) in terms of tolerance to redox cycles, and to minimise fuel preprocessing for the direct use of readily available hydrocarbons in SOFCs, alternative ceramic‐based anode substrate materials and functional anode materials were investigated, with the emphasis on perovskite oxides. Compared to (Sr,La)TiO3–δ and Nb2TiO7–δ, (Sr,Y)TiO3–δ ceramics (SYT, with a Y content of about 7 at.‐%) reduced at high temperatures are promising redox‐stable anode substrate materials due to their very small dimensional change upon redox cycling (0.14%). Correspondingly, the composite ceramic SYT/YSZ impregnated with ∼5 vol.‐% Ni has a good chance of being applied as a redox‐stable functional anode material due to its even smaller dimensional change upon redox cycling (<0.05%) and superior electrochemical performance for H2 oxidation (polarisation resistance ∼0.2 Ω cm2 at 800 °C). The small fraction of Ni homogeneously dispersed on the pore walls of the SYT/YSZ ceramic framework significantly enhances the electrocatalytic activity, and should not have a detrimental effect on the redox stability of the electrode. In addition, two mixed conductors with perovskite structure, (La0.8Sr0.2)0.94Al0.5Mn0.5O3–δ and La0.4Sr0.6Ti0.4Mn0.6O3–δ, were also investigated. They show promising electrochemical performance for the oxidation of H2. However, the high‐level Mn substitution which seems necessary to achieve a significant electrical conductivity and catalytic activity has a detrimental effect on the chemical stability of these two materials. Consequently, they show relatively large and irreversible chemical expansion and are thus not considered to be qualified functional anode materials.