bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of surface and free‐air temperature variability and trends at radiosonde sites and nearby high elevation surface stations
Authors: Pepin N. C. , Duane W.
Published: June 2007

Previous research has illustrated differences in temperature trends as measured by high elevation surface stations versus free‐air temperatures interpolated to the same locations from the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research's (NCAR) Re‐analysis R1. This paper examines the extent to which the decision to use R1 rather than radiosonde data influenced these results. Temperatures at selected high elevation surface sites (1948–998) are paired with nearby homogeneity adjusted radiosonde data from Lanzante, Klein and Seidel (LKS). For each station pair, four mean monthly temperature anomaly time series are examined, consisting of (1) surface Global Historical Climate Network (GHCNv2)/Climate Research Unit (CRUv2) station anomalies (SF), (2) LKS radiosonde anomalies, and R1 anomalies interpolated to (3) the surface (RNSF) and (4) radiosonde (RNLKS) locations respectively. Analyses demonstrate the extent of common variance, the mean climatology of each of the four series, and differences or similarities in trends. The surface record is decoupled from the other three series especially in locations of incised topography. In 15 out of 18 pairs RNSF shows greater affinity with LKS than with SF and there is a high degree of common variance between LKS and RNSF. There is a high degree of correlation between secular trends in the two R1 series, both of which are much more similar to radiosonde than to surface trends. Trends in raw temperature and in ΔT (the surface/free‐air temperature difference) both therefore show limited sensitivity to the choice of LKS radiosonde versus R1 (RNSF), apart from in a few locations in the Eurasian continent. Copyright © 2007 Royal Meteorological Society
Erosion predictions with the Wind Erosion Equation (WEQ) using different climatic factors
Authors: Panebianco J. E. , Buschiazzo D. E.
Published: June 2007

Little information is available on the performance of the Wind Erosion Equation (WEQ) for estimating wind erosion under differing climatic conditions. The objective of this study was to assess the fitting of measured and WEQ‐estimated wind erosion with different climatic C factors. Results showed that WEQ underestimated the annual wind erosion by 45 per cent when loaded with the historic C, obtained with climatic data records between 1981 and 1990. The monthly averaged C factor (monthly C, n = 12) underestimated the erosion by 29 per cent, the C factors of each one of the six studied years (annual C, n = 6) underestimated the erosion by 19 per cent, and the C factors of each one of the evaluated months (monthly C, n = 72) overestimated the erosion by 31 per cent. Precipitation explained most of C factors variability. C factors corresponding to high precipitation periods predicted low erosion amounts in no‐till (NT) and conventional tillage (CT). C factors corresponding to low precipitation periods calculated high erosion rates in CT (143 t ha−1 y−1) and low in NT (2·4 t ha−1 y−1). The historical C factor predicted no erosion in NT and 7·1 t ha−1 y−1 in CT. These results indicated that the WEQ should be used with variable C factors in order to assess different climatic scenarios of the semiarid Argentina. Copyright © 2007 John Wiley & Sons, Ltd.
Land rights regimes in southwest Nigeria: implications for land access and livelihoods security of settled Fulani agropastoralists
Authors: Fabusoro E. , Matsumoto T. , Taeb M.
Published: June 2007

The need of Fulanis for secured access to land is a long time policy challenge in Nigeria but progress in achieving this is far from being made. Meanwhile, access to land, of Fulanis that are settled among the Yorubas in southwest Nigeria, is dependent on land rights regimes operating in Yoruba communities. The study examines the nature of land rights in southwest Nigeria and how these provide access to Fulanis for their livelihoods activities. The study hypothesised that land access and land rights relate significantly to livelihood security of the Fulanis. The study was conducted in three States, namely, Ogun, Oyo and Ekiti States. Two major settlements of the Fulanis were selected from each of the States and 20 Fulani households were sampled purposively from each settlement. Forty‐two Yoruba farmers were also interviewed to understand the land rights regimes operating in their communities. Non‐parametric Chi‐square analysis was conducted to test the hypotheses. The study revealed that communal land right regime operates in most communities in the region and designates use rights to Fulanis. Fulanis in Oyo State had management rights which gave them secured access to land in their host communities than their counterparts in other States. The hypotheses tested show significant relationship between land rights and livelihood security of the Fulanis (α < 0·05). The rehabilitation of existing grazing reserves in the region is therefore recommended to grant the Fulanis ownership rights and secured access to land for the security of their livelihoods. Copyright © 2007 John Wiley & Sons, Ltd.
The transient equations of viscous quantum hydrodynamics
Authors: Dreher Michael
Published: June 2007

We study the viscous model of quantum hydrodynamics in a bounded domain of space dimension 1, 2, or 3, and in the full one‐dimensional space. This model is a mixed‐order partial differential system with nonlocal and nonlinear terms for the particle density, current density, and electric potential. By a viscous regularization approach, we show existence and uniqueness of local in time solutions. We propose a reformulation as an equation of Schrödinger type, and we prove the inviscid limit. Copyright © 2007 John Wiley & Sons, Ltd.
Efficient handling of stability problems in shell optimization by asymmetric ‘worst‐case’ shape imperfection
Authors: Kegl M. , Brank B. , Harl B. , Oblak M. M.
Published: June 2007

The paper presents an approach to shape optimization of proportionally loaded elastic shell structures under stability constraints. To reduce the stability‐related problems, a special technique is utilized, by which the response analysis is always terminated before the first critical point is reached. In this way, the optimization is always related to a precritical structural state. The necessary load‐carrying capability of the optimal structure is assured by extending the usual formulation of the optimization problem by a constraint on an estimated critical load factor. Since limit points are easier to handle, the possible presence of bifurcation points is avoided by introducing imperfection parameters. They are related to an asymmetric shape perturbation of the structure. During the optimization, the imperfection parameters are updated to get automatically the ‘worst‐case’ pattern and amplitude of the imperfection. Both, the imperfection parameters and the design variables are related to the structural shape via the design element technique. A gradient‐based optimizer is employed to solve the optimization problem. Three examples illustrate the proposed approach. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis, characterization, and mechanical properties evaluation of thermally stable apophyllite vinyl ester nanocomposites
Authors: Chen Chenggang , Yebassa D. , Raghavan D.
Published: June 2007

The objective of this study is to prepare layered organosilicates with enhanced thermal stability that can be used to formulate high‐temperature polymer nanocomposites. Fourier transform infrared (FTIR) spectroscopy, wide‐angle X‐ray diffraction (WAXD), and thermal gravimetric analysis (TGA) characterization results of the modified silicates indicate that the organic pendant group has been chemically grafted on to the backbone of layered silicate and the organically modified apophyllite is thermally stable up to approximately 430°C. The organically modified apophyllite was mixed along with vinyl ester resin and styrene diluent in a sonic dismembrator and the mixture cured to form a nanocomposite specimen. Transmission electron microscopy (TEM) results of the nanocomposites showed mixed morphology with predominant fraction of organosilicates exhibiting an intercalated structure. Tapping mode atomic force microscopy (TMAFM) observation of the nanocomposite showed striated layered silicates dispersed in the resin matrix. The nanocomposites formulated with organosilicates containing reactive terminal pendant group were found to have a higher tensile strain than the nanocomposites formulated with organosilicates containing inert pendant group. Copyright © 2007 John Wiley & Sons, Ltd.
Development of noninvasive fetal DNA diagnosis from nucleated erythrocytes circulating in maternal blood
Authors: Sekizawa Akihiko , Purwosunu Yuditiya , Farina Antonio , Okai Takashi , Takabayashi Haruo , Kita Mikiko , Yura Hirofumi , Kitagawa Michihiro
Published: June 2007

Background

A considerable effort is being spent in developing noninvasive prenatal DNA diagnostic procedures. We recently reported that nucleated erythrocytes (NRBCs) can be enriched from maternal blood by a galactose‐specific lectin method. In the present study, to prove that fetal NRBCs are definitely present in maternal blood and are a good source for fetal genetic diagnosis, we evaluated methods for lectin enrichment and subsequent fluorescence in situ hybridization (FISH) analysis through fetal gender determination.

Methods

Peripheral blood samples were collected from pregnant women (median 15, range: 10–18 weeks). From the blood samples, NRBCs were enriched based on galactose‐specific lectin method. After detecting them by their morphology, NRBCs are separated and taken in a new glass slide by micromanipulator. We analyzed fetal gender using X and Y‐chromosome‐specific FISH probes. The results were compared with fetal gender analysis using Y‐chromosomal sequences in maternal plasma.

Results

The fetal gender analyses by FISH in 20 pregnant women were all in accordance with the results from maternal plasma analyses. It is confirmed that fetal NRBCs were present in maternal blood and that 30.4% of NRBCs in maternal blood were fetal in origin.

Conclusion

We have successfully carried out a noninvasive prenatal DNA diagnosis of fetal gender by using galactose‐specific lectin method and subsequent FISH analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis of dendronized polymer brushes containing metallo‐supramolecular polymer side chains
Authors: Zhang Yanhong , Xu Zizhen , Li Xiaokai , Chen Yongming
Published: June 2007

A new kind of dendronized polymer brush with metallo‐supramolecular polymer side chains was fabricated by a combination of macromonomer and graft‐to approach. The alternating copolymers of maleic anhydride and styryl macromonomers pendant with Fréchet‐type dendrons of three generations were reported previously. In this article, terpyridine groups were introduced along the backbone of the dendronized polymers through the amidolysis of anhydride groups. The terpyridine functionalized PEO linear chains were then incorporated through the complexation of terpyridine and Ru(II) ion. Thus, dendronized polymer brushes with amphiphilic properties were synthesized. AFM analysis showed worm‐like single molecular morphologies of the polymers of three generations, and 1H NMR analysis indicated that such molecular brushes had an amphiphilic nature in solution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3303–3310, 2007
Nanostructured polymetallaynes of controlled length: Synthesis and characterization of oligomers and polymers from 1,1′‐bis‐(ethynyl)4,4′‐biphenyl bridging Pt(II) or Pd(II) centers
Authors: Fratoddi Ilaria , Battocchio Chiara , Groia Alessandra L. , Russo Maria V.
Published: June 2007

The reactivity of square planar palladium(II) and platinum(II) complexes in trans or cis configuration, namely trans or cis‐[dichlorobis(tributylphosphine)platinum(II)] and trans‐[dichlorobis(tributylphosphine)palladium(II)] with 1,1′‐bis(ethynyl) 4,4′‐biphenyl, DEBP, leading to π‐conjugated organometallic oligomeric and polymeric metallaynes, was investigated by a systematic variation of the reaction conditions. The formation of polymers and oligomers with defined chain length [M(PBu3)2 (CCC6H4C6H4CC)]n (n = 3–10 for the oligomers, n = 20–50 for the polymers) depends on the configuration of the precursor Pt(II) and Pd(II) complexes, the presence/absence of the catalyst CuI, and the reaction time. A series of model reactions monitored by XPS, GPC, and NMR 31P spectroscopy showed the route to modulate the chain growth. As expected, the nature of the transition metal (Pt or Pd) and the molecular weight of the polymers markedly influence the photophysical characteristics of the polymetallaynes, such as optical absorption and emission behavior. Polymetallaynes with nanostructured morphology could be obtained by a simple casting procedure of polymer solutions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3311–3329, 2007
Divergent synthesis of dendrimer‐like macromolecules through a combination of atom transfer radical polymerization and click reaction
Authors: Liu Qingchun , Zhao Peng , Chen Yongming
Published: June 2007

This article describes a divergent strategy to prepare dendrimer‐like macromolecules from vinyl monomers through a combination of atom transfer radical polymerization (ATRP) and click reaction. Firstly, star‐shaped polystyrene (PS) with three arms was prepared through ATRP of styrene starting from a three‐arm initiator. Next, the terminal bromides of the star‐shaped PS were substituted with azido groups. Afterwards, the azido‐terminated star‐shaped PS was reacted with propargyl 2,2‐bis((2′‐bromo‐2′‐methylpropanoyloxy)methyl)propionate (PBMP) via click reaction. Star‐shaped PS with six terminal bromide groups was afforded and served as the initiator for the polymerization of styrene to afford the second‐generation dendrimer‐like PS. Iterative process of the aforementioned sequence of reactions could allow the preparation of the third‐generation dendrimer‐like PS. When the second‐generation dendrimer‐like PS with 12 bromide groups used as an initiator for the polymerization of tert‐butyl acrylate, the third‐generation dendrimer‐like block copolymer with a PS core and a poly (tert‐butyl acrylate) (PtBA) corona was afforded. Subsequently PtBA segments were selectively hydrolyzed with hydrochloric acid, resulting an amphiphilic branched copolymer with inner dendritic PS and outer linear poly(acrylic acid) (PAA). Following the same polymerization procedures, the dendrimer‐like PS and PS‐block‐PtBA copolymers of second generation originating from six‐arm initiator were also synthesized. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3330–3341, 2007
Preparation and morphological, electrical, and mechanical properties of polyimide‐grafted MWCNT/polyimide composite
Authors: Yuen Siu‐Ming , Ma Chen‐Chi M. , Chiang Chin‐Lung , Lin Yao‐Yu , Teng Chih‐Chun
Published: June 2007

Precursor of polyimide, polyamic acid has been prepared sucessfully. Acid‐modified carbon nanotube (MWCNT) was grafted with soluble polyimide then was added to the polyamic acid and heated to 300 °C to form polyimide/carbon nanotube composite via imidation. Morphology, mechanical properties and electrical resistivity of the MWCNT/polyimide composites have been studied. Transmission electron microscope microphotographs show that the diameter of soluble polyimide‐grafted MWCNT was increased from 30–60 nm to 200 nm, that is a thickness of 70–85 nm of the soluble polyimide was grafted on the MWCNT surface. PI‐g‐MWCNT was well dispersed in the polymer matrix. Percolation threshold of MWCNT/polyimide composites has been investigated. PI‐g‐MWCNT/PI composites exhibit lower electrical resistivity than that of the acid‐modified MWCNT/PI composites. The surface resistivity of 5.0 phr MWCNT/polyimide composites was 2.82 × 108 Ω/cm2 (PI‐g‐MWCNT) and 2.53 × 109 Ω/cm2 (acid‐modified MWCNT). The volume resistivity of 5.0 phr MWCNT/polyimide composites was 8.77 × 106 Ω cm (PI‐g‐MWCNT) and 1.33 × 1013 Ω cm (acid‐modified MWCNT).Tensile strength and Young's modulus increased significantly with the increase of MWCNT content. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3349–3358, 2007
Morphology of PU/PMMA hybrid particles from miniemulsion polymerization: Thermodynamic considerations
Authors: Li Chien‐Yu , Chiu Wen‐Yen , Don Trong‐Ming
Published: June 2007

The morphology of PU/PMMA hybrid particles prepared by miniemulsion polymerization was predicted through the consideration of their Gibbs free energy changes. Five morphological states of PU/PMMA hybrid particles were proposed and their Gibbs free energy changes were calculated. Before the formation of hybrid particles, the initial state included a monomer mixture of PU prepolymer, MMA, a chain extender, TMP, and an initiator, which was in droplets suspended in water containing SDS. Two assumptions were made. First, the densities of all states were the same. Secondly, secondary nucleation of particles was negligible. Thus the size of initial droplet and final particle was unchanged through miniemulsion polymerization. The interfacial tensions were measured by a pendant drop method and were used for calculation. The preferred morphology of PU/PMMA hybrid particle had the minimum value of ΔGphase. Different NCO/OH ratios of PU and initiators of MMA were used to study the morphological change of PU/PMMA hybrid particles. When BD was used as the chain extender of PU, the hybrid particles showed the PU‐rich phase as the shell and PMMA‐rich as the core. When incorporating bisphenol A into PU polymer, the homogeneous structure of hybrid particle was preferred. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3359–3369, 2007
Model reaction for thermally latent curing through addition of hemiacetal ester and epoxide by schiff‐base–zinc halide complexes
Authors: Komatsu Hiroyuki , Ochiai Bungo , Hino Tetsuo , Endo Takeshi
Published: June 2007

Schiff‐base–zinc halide complexes (ZnX2/1) thermal‐latently catalyze the reaction of glycidyl phenyl ether (2) and 1‐propoxyethyl 2‐ethylhexanoate (3) that proceeds at moderately elevated temperatures. The catalysis by the ZnX2/1 complexes proceeds via the thermal dissociation of 3 to produce the corresponding carboxylic acid that nucleophilically attacks 2 predominantly over the thermally dissociated vinyl ether. ZnX2/1 complexes catalyze both the dissociation of 3 to produce the carboxylic acid intermediate and its addition to 2. Although conventional latent catalysts for this reaction exhibit Lewis acidities under ambient conditions that are responsible to the gradual degradation of hemiacetal esters and the polymerization of epoxides, a mixture of 2, 3, and ZnX2/1 can be stored for 3 months at ambient conditions. The stored mixture is as active as the freshly prepared mixture, keeping the excellent activity and latency of ZnX2/1. As well as the model reaction, the thermally latent polyaddition of bisphenol A diglycidyl ether (9) and di‐1‐propoxyethyl adipate (10) is also promoted with ZnCl2/1 at a moderate elevated temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3370–3379, 2007
Synthesis and properties of polyurethanes bearing urethane moieties in the side chain
Authors: Ochiai Bungo , Sato Shin‐Ich , Endo Takeshi
Published: June 2007

Polyurethanes bearing urethane groups in the side chains were prepared by the addition of isocyanates to the hydroxyl groups in poly(hydroxyurethane) prepared by the polyaddition of a bifunctional cyclic carbonate with 1,12‐diaminododecane. The urethanization proceeded quantitatively in the presence of a catalytic amount of di‐n‐butyltin dilaurate. The resulting polyurethane had a higher glass transition temperature than the original poly(hydroxyurethane), although its esterified product had a lower glass transition temperature. The urethanization with 3‐(triethoxysilyl)propyl isocyanate also proceeded effectively to afford both soluble and insoluble polymers, depending on the reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3408–3414, 2007
Highly active ethylene polymerization and copolymerization with norbornene using bis(imino‐indolide) titanium dichloride–MAO system
Authors: Zuo Weiwei , Sun Wen‐Hua , Zhang Shu , Hao Peng , Shiga Akinobu
Published: June 2007

A catalytic system of new titanium complexes with methylaluminoxane (MAO) was found to effectively polymerize ethylene for high molecular weight polyethylene as well as highly active copolymerization of ethylene and norbornene. The bis (imino‐indolide)titanium dichlorides (L2TiCl2, 1–5), were prepared by the reaction of N‐((3‐chloro‐1H‐indol‐2‐yl)methylene)benzenamines with TiCl4, and characterized by elemental analysis, 1H and 13C NMR spectroscopy. The solid‐state structures of 1 and 4 were determined by X‐ray diffraction analysis to reveal the six‐coordinated distorted octahedral geometry around the titanium atom with a pair of chlorides and ligands in cis‐forms. Upon activation by MAO, the complexes showed high activity for homopolymerization of ethylene and copolymerization of ethylene and norbornene. A positive “comonomer effect” was observed for copolymerization of ethylene and norbornene. Both experimental observations and paired interaction orbital (PIO) calculations indicated that the titanium complexes with electron‐withdrawing groups in ligands performed higher catalytic activities than those possessing electron‐donating groups. Relying on different complexes and reaction conditions, the resultant polyethylenes had the molecular weights Mw in the range of 200–2800 kg/mol. The influences on both catalytic activity and polyethylene molecular weights have been carefully checked with the nature of complexes and reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3415–3430, 2007
A novel and facile preparation method of hollow silica spheres containing small SiO2 cores
Authors: Cheng Xinjian , Chen Min , Wu Limin , You Bo
Published: June 2007

This article presents a novel and facile preparation method of hollow silica spheres with loading small silica inside. In this approach, positively charged SiO2/polystyrene core‐shell composite particles were synthesized first, when the silica shells from the sol‐gel process of tetraethoxysilane were then coated on the surfaces of composite particles via electrostatic interaction, the polystyrene was dissolved subsequently even synchronously in the same medium to form hollow silica spheres with small silica cores. TEM, SEM, and FTIR measurements were used to characterize these composite spheres. Based on this study, some inorganic or organic compounds could be loaded into these hollow silica spheres. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3431–3439, 2007
Synthesis and opto‐electrical properties of dendron‐containing poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives
Authors: Yang Sheng‐Hsiung , Chen Shiang‐Ying , Wu Yu‐Chun , Hsu Chain‐Shu
Published: June 2007

A new series of poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives containing dendritic side groups were synthesized. Different generations of dendrons were integrated on the pendant phenyl ring to investigate their effect on optical and electrical properties of final polymers. Homopolymers can not be obtained via the Gilch polymerization because of sterically bulky dendrons. By controlling the feed ratio of different monomers during polymerization, dendron‐containing copolymers with high molecular weights were obtained. The UV–vis absorption and photoluminescent spectra of the thin films are pretty close; however, quantum efficiency is significantly enhanced with increasing the generation of dendrons. The electrochemical analysis reveals that hole‐injection is also improved by increasing dendritic generation. Double‐layer light‐emitting devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated. High generation dendrons bring benefit of improved device performance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3440–3450, 2007
Calorimetry in nonstandard conditions: The noncrystalline phases of linear polyethylene
Authors: Jedidi Ilyes , Ferhat‐Hamida Zohra , Delmas Geneviève
Published: June 2007

A linear Union Carbide PE (UC) has been analyzed by nonstandard calorimetry with a common DSC calorimeter and a Setaram C80 calorimeter. Nonstandard calorimetry entails using a low rate of heating (0.5–1 K/min), a small mass (0.5–1.5 mg), and an open cell (O‐cell) instead of the standard C‐cell. Events in O‐cells overlap less and occur with a faster kinetics than in C‐cells. PE crystals are nascent, solution‐grown (S‐grown), press‐grown (P‐grown), and strained by extrusion. In Part A, the traces show that the phase‐changes in the melt, previously observed in a C80 calorimeter (slow T‐ramp) and characterized by ΔHnetwork, can be observed with a common DSC in nonstandard conditions. In Part B, the difference between the C‐ and O‐cells and the changes in the main peak enthalpy (ΔHortho) are of interest. The main result is that, in O‐cells, the value of ΔHortho around Tortho, exceeds unambiguously in certain conditions ΔHortho found for perfect orthorhombic crystals. The main endotherm contains then another contribution, namely ΔHnetwork. Crystal reorganization during the slow T‐ramp is followed in the C‐ and O‐cells on S‐grown crystals. In O‐cells, lamellar thickening observed in the slow‐ramp is more extensive. The ease of phase‐change depends on the sample history. It is as follows: strained‐part extruded > nascent > S‐grown > P‐grown. Co‐operative chain motions are more hindered in the standard C‐cells than in the O‐cells. In Part C, lower values of m succeed in bringing phase‐changes in P‐grown (O‐cells) samples. The origin of the events is discussed: three processes are thought to contribute to the phase‐changes namely, melting of strained short‐range order, activation of vibrations in the CH2 groups, and fast decay of chain orientation which occurs simultaneously with melting. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1932–1949, 2007
Surface‐treated and multilayered poly(ε‐caprolactone) nanofiber webs exhibiting enhanced hydrophilicity
Authors: Kim Geunhyung , Park Jongha , Park Sua
Published: June 2007

To improve the hydrophilic properties of poly(ε‐caprolactone) (PCL) nano/microfiber webs for tissue engineering scaffolds, PCL webs of various structures were fabricated by electrospinning with single or double nozzles connected to an auxiliary electrode. Surface‐modified and layered PCL fiber webs were made by including water‐soluble poly(ethylene oxide) (PEO) in the PCL electrospinning solution (single‐nozzle method) or by electrospinning of alternating PCL and PEO solutions using two nozzles (double‐nozzle method), respectively. When the PEO component within the resulting webs was removed by dissolution with distilled water, the remnant PCL webs exhibited two distinct structures. Those made by the single‐nozzle method consisted of nanofibers with high surface roughness, whereas those made by the double‐nozzle method consisted of stacked layers of PCL nanofibers. Both types of structured PCL web showed improved hydrophilicity characteristics compared with those of nanofiber webs generated from a pure PCL solution using a typical electrospinning process. Cell culturing and scanning electron microscopy showed that the interactions between human dermal fibroblasts and the structured PCL scaffolds were very favorable. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2038–2045, 2007
Uptake and translocation of non‐ionised pesticides in the emergent aquatic plant parrot feather Myriophyllum aquaticum
Authors: de Carvalho Renato F , Bromilow Richard H , Greenwood Richard
Published: June 2007

The uptake of four 14C‐labelled non‐ionised compounds, the methyl carbamoyloxime insecticide/nematicide oxamyl and three model phenylureas, from solution by rooted stems of the aquatic plant parrot feather [Myriophyllum aquaticum (Vell.) Verdc], together with translocation to the emergent shoots, was measured over periods of 24 and 48 h. Uptake into the submerged tissues of roots and stem base could be ascribed to two processes: movement into the aqueous phase of cells and then partitioning onto the plant solids. This latter process was related to lipophilicity (as measured by the l‐octanol/water partition coefficient, Kow) and gave rise to high uptake rates of the most lipophilic compounds. Translocation to shoots was passive and was optimal at log Kow ∼ 1.8, at which the efficiency of translocation of compound was about 40% of that of water. This optimum log Kow was identical to that observed previously in barley, although the translocation efficiency was somewhat less in parrot feather. Solvation parameters were applied to model uptake and translocation of a set of ten compounds by barley with the particular objective of understanding why translocation efficiency is lower at log Kow > 1.8. Copyright © 2007 Society of Chemical Industry
Insecticide resistance status of Myzus persicae (Hemiptera: Aphididae) populations from peach and tobacco in mainland Greece
Authors: Margaritopoulos John T , Skouras Panagiotis J , Nikolaidou Parthena , Manolikaki Joanna , Maritsa Katherine , Tsamandani Kiveli , Kanavaki Olympia M , Bacandritsos Nikolaos , Zarpas Kostas D , Tsitsipis John A
Published: June 2007

The susceptibility of 88 and 38 field samples of Myzus persicae (Sulzer) to imidacloprid and deltamethrin respectively was examined using the FAO dip test bioassay. The field samples were collected from tobacco and peach from various regions of Greece in the period from 2004 to 2006. In addition, 497, 349 and 370 clones originating from peach and tobacco were screened for the three known resistance mechanisms, elevated esterases, modified acetylcholinesterase (MACE) and knockdown resistance (kdr) respectively, using biochemical and DNA diagnostics. Most of the samples assayed with imidacloprid showed low resistance factors (RFs)–39% below 5 and 21% between 5 and 10. However, 9% of the samples (all from tobacco) showed relatively high RF values (24–73). Differences were found between crops, with higher RF values recorded in samples from tobacco than in those from peach. Bioassays with deltamethrin revealed the development of strong resistance in the populations examined. The RFs were mostly higher than 23, and in 29% of the samples they were extremely high (152–436). Finally, the three known resistance mechanisms were found in high frequencies in the populations examined, although some differences between crops and years were detected. The implications of the study for management schemes against M. persicae are discussed. Copyright © 2007 Society of Chemical Industry
The multipartite system that mediates entry of herpes simplex virus into the cell
Authors: Campadelli‐Fiume Gabriella , Amasio Michele , Avitabile Elisa , Cerretani Arianna , Forghieri Cristina , Gianni Tatiana , Menotti Laura
Published: June 2007

The multipartite entry‐fusion system of herpes simplex virus is made of a quartet of glycoproteins—gD, gB, gH·gL—and three alternative gD receptors, herpesvirus entry mediator (HVEM), nectin1 and modified sites on heparan sulphate. This multipartite system recapitulates the basic steps of virus—cell fusion, i.e. receptor recognition, triggering of fusion and fusion execution. Specifically, in addition to serving as the receptor‐binding glycoprotein, gD triggers fusion through a specialised domain, named pro‐fusion domain (PFD), located C‐terminally in the ectodomain. In the unliganded gD the C‐terminal region folds around the N‐terminal region, such that gD adopts a closed autoinhibited conformation. In HVEM‐ and nectin1‐bound gD the C‐terminal region is displaced (opened conformation). gD is the tool for modification of HSV tropism, through insertion of ligands to heterologous tumour‐specific receptors. It is discussed whether gD responds to the interaction with the natural and the heterologous receptors by adopting similar conformations, and whether the closed‐to‐open switch in conformation is a generalised mechanism of activation. A peculiar recombinant highlighted that the central Ig‐folded core of gD may not encode executable functions for entry and that the 219–314 aa segment may be sufficient to trigger fusion. With respect to fusion execution, gB appears to be a prospective fusogen based on its coiled‐coil trimeric structure, similar to that of another fusion glycoprotein. On the other hand, gH exhibits molecular elements typical of class 1 fusion glycoproteins, in particular heptad repeats and strong tendency to interact with lipids. Whether fusion execution is carried out by gB or gH·gL, or both glycoproteins in complex or sequentially remains to be determined. Copyright © 2007 John Wiley & Sons, Ltd.
Passage of non‐salmonid fish through a Deelder lock on a lowland river
Authors: Baumgartner Lee J. , Harris John H.
Published: June 2007

An ineffective submerged orifice fishway was retrofitted with a Deelder lock and assessed for fish passage over two consecutive years (2002–2003) at Balranald Weir on the Murrumbidgee River, Australia. The assessment, using paired entrance and exit sampling, over three different cycle times, yielded a total of 13 448 fish (11 species) and 859 freshwater prawns (one species) passing through the lock. Australian smelt Retropinna semoni Weber, bony herring Nematolosa erebi Günther and western carp gudgeon Hypseleotris spp contributed 89% of the total catch. The maximum number of fish caught in a single day was 854. Cycle time did not have a significant effect on the abundance or composition of fish using the fishlock and sizes of fish sampled from the exit trap ranged from 12 to 540 mm fork length. Length–frequency analysis also demonstrated that all size classes of the most common species were able to negotiate the lock successfully. Movement of fish varied significantly with time of the day. The greatest movement occurred between 1200 and 1600 and few fish migrated at dawn or at night. The Deelder lock improved passage for a much wider range of species and size classes than within the existing submerged orifice designs in other areas of the Murray‐Darling Basin. The design is therefore recommended for installation at other sites, especially where small‐fish passage is a priority. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of nano‐organized multilayers constituted by successive inorganic (gold) and organic (alkylthiols) layers
Authors: Kazzi Yolla , Awada Houssein , David Marie‐Odile , Nardin Michel
Published: June 2007

Nanostructured multilayers constituted by alternate metallic (gold) and organic (alkyldithiol) layers, and grafted onto glass or silicon substrates are prepared and analysed. Such complex layers could be of interest as a new type of surfaces but also as localized dissipative zones particularly in the field of adhesion science. The formation and the structure of these model systems are examined using a number of techniques such as atomic force microscopy (AFM), wetting analysis (contact angles), X‐ray photoelectron spectroscopy (XPS) and conductivity measurements. It is shown that, in terms of electrical conductivity, gold layers exhibit a percolation transition from an insulating granular structure to a conductive worm‐like structure at a threshold thickness of about 5 nm. XPS (and wettability) analyses clearly indicate that the fractional coverage of the gold surface is about 30% with alkyldithiol and that these molecules are either grafted in a stand‐up position or in the form of a loop. Moreover, a partial electrical connection between two successive gold layers is observed, confirming that the confined organic layer of alkyldithiol between them is too loosely organized to play the role of an insulating barrier. Copyright © 2007 John Wiley & Sons, Ltd.
Frequentist evaluation of group sequential clinical trial designs
Authors: Emerson Scott S. , Kittelson John M. , Gillen Daniel L.
Published: June 2007

Group sequential stopping rules are often used as guidelines in the monitoring of clinical trials in order to address the ethical and efficiency issues inherent in human testing of a new treatment or preventive agent for disease. Such stopping rules have been proposed based on a variety of different criteria, both scientific (e.g. estimates of treatment effect) and statistical (e.g. frequentist type I error, Bayesian posterior probabilities, stochastic curtailment). It is easily shown, however, that a stopping rule based on one of these criteria induces a stopping rule on all other criteria. Thus, the basis used to initially define a stopping rule is relatively unimportant so long as the operating characteristics of the stopping rule are fully investigated. In this paper we describe how the frequentist operating
characteristics of a particular stopping rule might be evaluated to ensure that the selected clinical trial design satisfies the constraints imposed by the many different disciplines represented by the clinical trial collaborators. Copyright © 2007 John Wiley & Sons, Ltd.
Bayesians in clinical trials: Asleep at the switch
Authors: Moyé Lemuel A.
Published: June 2007

The refreshing Bayes perspective has much to offer biostatistics. Yet, from its 225‐year‐old roots sprung difficulties that blocked its growth at the beginning of the 20th century. Computational obstacles in concert with an inability to identify the best indifferent prior revealed a weakness on which frequentists capitalized. It took Bayesians 40 years to recover, allowing the infant field of biostatistics to fall firmly in the hands of the frequentists. Recent disillusionment with the frequentist perspective, and its hegemony ofp‐values, has produced a second opportunity for the Bayesian philosophy to make solid contributions to clinical trials.

However, difficulty with the applicability of the likelihood principle, problems with prevalent prior ‘disinformation’ in clinical medicine, in concert with the complexity of truly representative loss functions threaten again to thwart the Bayesian march into biostatistics. Seven suggestions are offered to the Bayesians to help them adapt to the rigors of clinical research. Copyright © 2007 John Wiley & Sons, Ltd.
Randomized phase II trials with a prospective control
Authors: Jung Sin‐Ho
Published: June 2007

We consider phase II trials randomizing patients between a prospective control and an experimental therapy. Proposed are two‐stage designs allowing for early termination of the study when the experimental arm does not show promising efficacy at the interim analysis. By using exact binomial distributions, the design characteristics, such as type I error and power, are exactly calculated. Given response probabilities for two arms, we define minimax and optimal designs that satisfy a prespecified restriction on type I and II error probabilities. These designs are randomized phase II trial analogs of Simon's designs that were proposed for single‐arm phase II trials. The methods for two‐arm trials are easily extended to multi‐arm trials with one control and K (⩾2) experimental arms. Some phase II trials are taken as real examples. Copyright © 2007 John Wiley & Sons, Ltd.
Case‐Matched Comparison of the Retroperitoneal Approach With Laparotomy for Necrotizing Pancreatitis
Authors: van Santvoort Hjalmar C. , Besselink Marc G. , Bollen Thomas L. , Buskens Erik , van Ramshorst Bert , Gooszen Hein G. ,   Dutch Acute Pancreatitis Study Group
Published: June 2007

Background

Minimally invasive necrosectomy through a retroperitoneal approach is gaining popularity for the treatment of necrotizing pancreatitis. There is, however, no substantial evidence from comparative studies in favor of this technique over laparotomy. The aim of this case‐matched study was to perform the first head‐to‐head comparison of necrosectomy by the retroperitoneal approach with laparotomy in patients with necrotizing pancreatitis.

Methods

Between 2001 and 2005, there were 15 of 841 consecutive acute pancreatitis patients who underwent necrosectomy by the retroperitoneal approach using a small flank incision. These patients were matched for the presence of preoperative organ failure, status of infection, timing of surgery, age, and computed tomography severity index score with 15 of 46 patients treated with necrosectomy by laparotomy and continuous postoperative lavage (CPL).

Methods

In addition to all matched preoperative characteristics, there were no significant differences in sex, preoperative intensive care unit (ICU) admission, preoperative ICU stay, preoperative APACHE‐II scores, and preoperative multiple organ failure (MOF). Postoperative complications requiring reintervention occurred in six patients in each group (p = 1.000). Postoperative new‐onset MOF occurred in 10 patients in the laparotomy/CPL group versus 2 patients in the retroperitoneal approach group (p = 0.008). Six patients died in the laparotomy/CPL group versus 1 patient in the retroperitoneal approach group (p = 0.080).

Conclusions

The less postoperative organ failure and the trend toward lower mortality may point to a benefit of the retroperitoneal approach over laparotomy. A randomized controlled design is, however, still required to answer definitively the question of which operative technique is preferably for patients with (infected) necrotizing pancreatitis.
Identification and characterization of human ribokinase and comparison of its properties with E. coli ribokinase and human adenosine kinase
Authors: Park Jae , van Koeverden Paul , Singh Bhag , Gupta Radhey S.
Published: June 2007

The gene responsible for ribokinase (RK) in human/eukaryotic cells has not yet been identified/characterized. Blast searches with E. coli RK have identified a human protein showing significant similarity to the bacterial RK. The cDNA for this protein was expressed in E. coli and the recombinant protein efficiently phosphorylated ribose to ribose‐5‐phosphate using ATP, confirming its identity as RK. In contrast to ribose, the enzyme exhibited very little to no phosphorylation of d‐arabinose, d‐xylose, d‐fructose and d‐galactose. The catalytic activity of human RK was dependent upon the presence of inorganic phosphate, as observed previously for E. coli RK and mammalian adenosine kinases (AK). A number of activators and inhibitors of human AK, produced very similar effects on the human and E. coli RKs, indicating that the catalytic mechanism of RK is very similar to that of the AKs.
Spawning sockeye salmon fossils in Pleistocene lake beds of Skokomish Valley, Washington
Authors: Smith Gerald R. , Montgomery David R. , Peterson N. Phil , Crowley Bruce
Published: June 2007

An assemblage of fossil sockeye salmon was discovered in Pleistocene lake sediments along the South Fork Skokomish River, Olympic Peninsula, Washington. The fossils were abundant near the head of a former glacial lake at 115 m elevation. Large adult salmon are concentrated in a sequence of death assemblages that include individuals with enlarged breeding teeth and worn caudal fins indicating migration, nest digging, and spawning prior to death. The specimens were 4 yr old and 45–70 cm in total length, similar in size to modern sockeye salmon, not landlocked kokanee. The fossils possess most of the characteristics of sockeye salmon, Oncorhynchus nerka, but with several minor traits suggestive of pink salmon, O. gorbuscha. This suggests the degree of divergence of these species at about 1 million yr ago, when geological evidence indicates the salmon were deposited at the head of a proglacial lake impounded by the Salmon Springs advance of the Puget lobe ice sheet. Surficial geology and topography record a complicated history of glacial damming and river diversion that implies incision of the modern gorge of the South Fork Skokomish River after deposition of the fossil-bearing sediments.
A Content-Centric Organization of the Genetic Code
Authors: Yu Jun
Published: June 2007

The codon table for the canonical genetic code can be rearranged in such a way that the code is divided into four quarters and two halves according to the variability of their GC and purine contents, respectively. For prokaryotic genomes, when the genomic GC content increases, their amino acid contents tend to be restricted to the GC-rich quarter and the purine-content insensitive half, where all codons are fourfold degenerate and relatively mutation-tolerant. Conversely, when the genomic GC content decreases, most of the codons retract to the AU-rich quarter and the purine-content sensitive half; most of the codons not only remain encoding physicochemically diversified amino acids but also vary when transversion (between purine and pyrimidine) happens. Amino acids with sixfold-degenerate codons are distributed into all four quarters and across the two halves; their fourfold-degenerate codons are all partitioned into the purine-insensitive half in favorite of robustness against mutations. The features manifested in the rearranged codon table explain most of the intrinsic relationship between protein coding sequences (the informational content) and amino acid compositions (the functional content). The renovated codon table is useful in predicting abundant amino acids and positioning the amino acids with related or distinct physicochemical properties.
A Brief Review of Short Tandem Repeat Mutation
Authors: Fan Hao , Chu Jia-You
Published: June 2007

Short tandem repeats (STRs) are short tandemly repeated DNA sequences that involve a repetitive unit of 1–6 bp. Because of their polymorphisms and high mutation rates, STRs are widely used in biological research. Strand-slippage replication is the predominant mutation mechanism of STRs, and the stepwise mutation model is regarded as the main mutation model. STR mutation rates can be influenced by many factors. Moreover, some trinucleotide repeats are associated with human neurodegenerative diseases. In order to deepen our knowledge of these diseases and broaden STR application, it is essential to understand the STR mutation process in detail. In this review, we focus on the current known information about STR mutation.
Alternative Splicing and Expression Profile Analysis of Expressed Sequence Tags in Domestic Pig
Authors: Zhang Liang , Tao Lin , Ye Lin , He Ling , Zhu Yuan-Zhong , Zhu Yue-Dong , Zhou Yan
Published: June 2007

Domestic pig (Sus scrofa domestica) is one of the most important mammals to humans. Alternative splicing is a cellular mechanism in eukaryotes that greatly increases the diversity of gene products. Expression sequence tags (ESTs) have been widely used for gene discovery, expression profile analysis, and alternative splicing detection. In this study, a total of 712,905 ESTs extracted from 101 different non-normalized EST libraries of the domestic pig were analyzed. These EST libraries cover the nervous system, digestive system, immune system, and meat production related tissues from embryo, newborn, and adult pigs, making contributions to the analysis of alternative splicing variants as well as expression profiles in various stages of tissues. A modified approach was designed to cluster and assemble large EST datasets, aiming to detect alternative splicing together with EST abundance of each splicing variant. Much efforts were made to classify alternative splicing into different types and apply different filters to each type to get more reliable results. Finally, a total of 1,223 genes with average 2.8 splicing variants were detected among 16,540 unique genes. The overview of expression profiles would change when we take alternative splicing into account.