bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative effect of biofertilizers on fodder production and quality in guinea grass (Panicum maximum Jacq.)
Authors: Mishra Seema , Sharma Satyawati , Vasudevan Padma
Published: May 2008

BACKGROUND: Panicum maximum Jacq. is one of the most important fodder grasses of the tropics. For good production and growth it requires high amounts of N fertilizer. Chemical fertilizers have a deleterious effect on soil fertility and are not economical for resource‐poor farmers. Utilization of plant growth‐promoting bacteria and fungi proved to be beneficial for improving crop production as well as the soil fertility. In the present paper the effect of inoculation of N fixer (Azospirillum brasilense) and P solubilizers (arbuscular mycorrhizal (AM) fungi consortia and inoculum of Glomus intraradiaces) was studied in single as well as mixed inoculation on forage yield and quality in guinea grass (Panicum maximum Jacq.) at different cuttings under the cut‐and‐carry system.

RESULTS: Overall five cuttings were obtained during the year. Dual inoculation, i.e., Azospirillum with indigenous AM consortia, significantly improved fodder growth, production and quality in terms of crude protein (CP) content, while neutral detergent fiber (NDF) and acid detergent fiber (ADF) content decreased after this treatment. The density of soil microbes (number of Azospirillum colony‐forming units, number of AM spores) was enhanced in mixed inoculation. Chemical fertilizer improved fodder production and CP content significantly over control but also enhanced NDF and ADF content and suppressed the Azospirillum colony‐forming units, AM spores and AM root infection.

CONCLUSION: It could be concluded from the present study that inoculated N fixer and P solubilizer have a synergistic effect which enhanced overall fodder production, quality and also beneficial microflora in the rhizosphere soil, which also demonstrated the sustainability of biofertilizers. Copyright © 2008 Society of Chemical Industry
Effects of forest plantations on rainfall redistribution and erosion in the red soil region of Southern China
Authors: Cao Y. , Ouyang Z. Y. , Zheng H. , Huang Z. G. , Wang X. K. , Miao H.
Published: May 2008

To evaluate the effects of different forest plantations on rainfall redistribution, we measured throughfall, stemflow, interception loss, surface runoff and soil loss from July 2004 to September 2005 in the three types of forest plantations Eucommia ulmoides, Vernicia fordii and Pinus massoniana. The results showed that differences in throughfall and stemflow between the three forest plantations were significant (p < 0·05). Throughfall was highest in the V.fordii plantation and stemflow was highest in the E.ulmoides plantation. Throughfall plus stemflow below the E.ulmoides canopy was greater than that underneath the other forest types. Moreover, significant spatial variation in throughfall was observed. Throughfall in P.massoniana was 28·0–39·7% higher at a stem distance < 60 cm or 11·5% lower at a stem distance > 120 cm than in the other forests, but the difference was not significant between E.ulmoides and V.fordii. Moreover, the difference in throughfall at stem distances 60–120 cm was not significant between the different forest plantations. For E.ulmoides, throughfall under the peripheral crown part was 16·1% higher than that close to the stem. In contrast to E.ulmoides, P.massoniana had 26·8% lower throughfall under the peripheral crown part than close to the stem. No significant difference was found in throughfall for the various stem distances underneath V.fordii. Stemflow in E.ulmoides was 2–3 times higher than in the other forests (p < 0·01). Interception loss accounted for 19·9% of gross rainfall for E.ulmoides, 20·8% for V.fordii and 27·2% for P.massoniana. Surface runoff and soil loss differed considerably among the three types of forest plantations. Annual runoff and total soil loss were lowest in the P.massoniana forest and highest in the V.fordii forest. This study indicated that P.massoniana, as a reforestation tree species, had the most positive effect on soil and water conservation among the three forest plantations. Copyright © 2008 John Wiley & Sons, Ltd.
Syntheses of Well‐Defined Glyco‐Polyorganosiloxanes by “Click” Chemistry and their Surfactant Properties
Authors: Halila Sami , Manguian Maggy , Fort Sébastien , Cottaz Sylvain , Hamaide Thierry , Fleury Etienne , Driguez Hugues
Published: May 2008

Well‐defined glyco‐polyorganosiloxanes were synthesized by the Cu(I)‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction (often simply referred to as “click” chemistry). N‐propargylglycosylamines 2 and 4 were first synthesized from cellobiose (1) and xylogluco‐oligosaccharide XGOs 3 without protecting groups. The azide function was introduced into polydimethylsiloxanes [PDMS: 5 (MD′M) and 7 (M′DM′)] by azidolysis of the counterpart epoxy silicon with NaN3 to afford the mono‐azido 6 and di‐azido 8 derivatives, respectively. The coupling reaction took place in a hydro‐alcoholic medium in the presence of CuSO4/sodium ascorbate as catalyst. Only one compound, MD′M‐“click”‐XGO 12 showed good solubility in water with interesting surfactant properties.

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Effect of Fullerene on Photocurrent Performance of 6‐O‐Porphyrin‐2,3‐di‐O‐stearoylcellulose Langmuir‐Blodgett Films
Authors: Sakakibara Keita , Nakatsubo Fumiaki
Published: May 2008

Thin films consisting of 6‐O‐porphyrin‐2,3‐di‐O‐stearoylcellulose (H2PCS) and fullerene (C60) were fabricated for anodic photocurrent generation systems by the Langmuir‐Blodgett (LB) technique. The π‐complexation between the porphyrin moiety and C60 in the LB films was investigated by means of the surface pressure (π)‐area (A) isotherms, UV‐vis, and fluorescence spectroscopy. The photocurrent density generated from the H2PCS–C60 LB monolayer films exhibited an increase with increasing the C60 proportion and reached a maximum at a mixing ratio of 1:2, yielding a quantum yield of 12.5% and an IPCE (incident photon‐to‐current efficiency) of 0.50% at a bias potential of +100 mV vs. SCE. Furthermore, the LB five‐layer films could give rise to the IPCE value of 1.5% at +100 mV without significant decline of the quantum yields, which was due to the function of C60 as an electron carrier to improve the interlayer electron transfer through each layer. These results have demonstrated a promising method for preparing the donor–acceptor systems using cellulose as a scaffold in the LB films.

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Synthesis of Double‐Hydrophilic BAB Triblock Copolymers via RAFT Polymerisation and their Thermoresponsive Self‐Assembly in Water
Authors: Skrabania Katja , Li Wen , Laschewsky André
Published: May 2008

Triblock copolymers of poly(N‐isopropylacrylamide)‐block‐poly(N,N‐dimethylacrylamide)‐block‐poly(N‐isopropylacrylamide) were synthesised via RAFT polymerisation using a symmetrical bistrithiocarbonate. Keeping the block length of the permanently hydrophilic middle block constant, the length of the poly(N‐isopropylacrylamide) block was varied broadly. The thermoresponsive aggregation of the polymers in water was studied by 1H NMR, turbidimetry, and dynamic light scattering. The complex aggregation behaviour was block length dependent and occurred under kinetic control. Importantly, different information on the hydrophilic‐hydrophobic transition of the poly(N‐isopropylacrylamide) block was obtained using the various analytical methods and could not be directly correlated.

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Preparation of Nanowells on a PS‐b‐PMMA Copolymer Thin Film by CO2 Treatment
Authors: Taki Kentaro , Waratani Yusuke , Ohshima Masahiro
Published: May 2008

Ordered nanowells with diameters of ca. 40 nm and depth of 1–2 nm were prepared on a poly(methyl methacrylate) (PMMA) spherical domain, which was exposed on the polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA) copolymer thin film. The PS‐b‐PMMA film formed spherical PMMA domains after the film was annealed above the order–disorder transition temperature. CO2 was dissolved into the PS‐b‐PMMA thin film at 8.6 MPa and at a temperature of 20 °C. The release of CO2‐pressure at the same temperature created the nanowell on the PMMA domain. The temperature and pressure to create nanowells in the PMMA domain affected the possibility of nanowell's formation.

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Liquid Crystalline Orientation of Semiconducting Nanorods in a Semiconducting Matrix
Authors: Zorn Matthias , Zentel Rudolf
Published: May 2008

This paper describes the synthesis of narrowly distributed block copolymers consisting of a hole conducting triarylamine block and an anchor block via RAFT polymerization. The anchor block is thereby introduced via a reactive ester approach. Block copolymers with dopamine anchor groups bind to oxidic semiconductors like TiO2, SnO2, and ZnO. Thus, it becomes possible to cover inorganic electron conducting (acceptor) nanomaterials with a corona of an organic hole conducting (donor) polymer like poly(triphenylamine), giving new hybrid materials. The poly(triphenylamine) grafted to inorganic nanorods allows the preparation of stable nanorod dispersions in appropriate solvents. At higher concentration the nanorods form liquid crystalline phases in various solvents and in a low Tg oligotriphenylamine matrix. This offers the potential to orient semiconducting inorganic nanorods in a hole conducting polymer matrix by self‐assembly.

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Supported (nBuCp)2ZrCl2 Catalysts: Effects of Selected Lewis Acid Organotin Silica Surface Modifiers on Ethylene Polymerization
Authors: Akhtar Muhammad N. , Atiqullah Muhammad , Moman Akhlaq A. , Abu‐Raqabah Atieh H. , Ahmed Neaz
Published: May 2008

This study investigated the effects of several organotin silica surface modifiers on the ethylene polymerization performance of (nBuCp)2ZrCl2‐based supported catalysts in which MAO and metallocene were sequentially loaded. Each organotin compound acted as a spacer, increasing the catalyst activity. However, the catalyst activity and $\overline M _{\rm w}$ of the resulting polyethylenes varied as follows:

Activity and fractional Sn+ charge: nBuSn(OH)2Cl > MeSnCl3 > nBuSnCl3 > Reference catalyst; and,

$\overline M _{\rm w}$: Reference catalyst > nBuSnCl3 > MeSnCl3 > nBuSn(OH)2Cl.

The above catalyst activity rating was explained considering the influence of the Lewis acidity, that is, the fractional Sn+ charge of the organotin modifiers on the generation, concentration, and electron density at the active [(nBuCp)2ZrMe]+ cation. All the catalysts showed fairly stable kinetic profiles and produced narrow molecular weight distribution resins; 2.8 ≤ PDI ≤ 3.

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Occupational therapy students' perceptions of their cultural awareness and competency
Authors: Murden Ravyn , Norman Ayana , Ross Julissa , Sturdivant Erin , Kedia Margaret , Shah Surya
Published: May 2008

Occupational therapy students' perceptions of cultural awareness and their self‐rated level of cultural competence were investigated. Seventy‐two participants at four stages of education (on entry, on completion of university‐based studies, on completion of fieldwork and one year following graduation) completed the Cultural Awareness and Sensitivity Questionnaire. The findings indicate that occupational therapy students graduated with an understanding of cultural diversity and the realization that cultural awareness and sensitivity are essential to culturally competent practice. The findings suggest that there is not enough exposure to cultural issues in both university‐based education and in fieldwork. This study was limited to one state university and to most students aged ≤24 years and predominantly female. It did not explore the factors that influence the development of cultural competence and the methods to develop it. Future studies should monitor actual culture‐related exposures to determine how learning experiences are organized and the ways culture influences the learning process and clinical competence. Copyright © 2008 John Wiley & Sons, Ltd.
Elderly persons with disabilities in Sweden: their experiences of everyday life
Authors: Tollén Anita , Fredriksson Carin , Kamwendo Kitty
Published: May 2008

The aim of this study was to describe the everyday life experiences of 22 elderly persons with physical disabilities in Sweden. The participants were aged between 65 and 91 years. Interviews were conducted and analysed according to a qualitative research approach. Disengagement in activities and social contacts resulted in feelings of resignation and dejection for some participants, while others delegated tasks as a satisfactory alternative. Participants also described how activities and social contacts continued, albeit in a different way, and being active and socializing gave feelings of pleasure and a sense of belonging. While receiving help was experienced as valuable, it also increased the fear of becoming dependent. Occupational therapy intervention should be directed at increasing social contacts and engagements in meaningful activities, as well as strengthening the individual's autonomy. The transferability of the study can be questioned as the sample only included elderly persons with physical disabilities from urban areas. Further research is needed to address the impact of occupational therapy interventions on life satisfaction. Copyright © 2008 John Wiley & Sons, Ltd.
A new family of low wear, low coefficient of friction polymer blend based on polytetrafluoroethylene and an aromatic thermosetting polyester
Authors: Zhang Jing , Demas Nicholaos G. , Polycarpou Andreas A. , Economy James
Published: May 2008

To improve the wear resistance of polytetrafluoroethylene (PTFE), a crosslinked aromatic thermosetting polyester (ATSP) has been blended directly with PTFE. Cured ATSP powder which was directly synthesized as a cured powder form was used for this application. Because of the similar processing temperature range of cured ATSP and PTFE, composites within the entire composition range were successfully prepared by blending these two powders using a hot press. Tribological pin‐on‐disk tests (composite pins sliding against gray cast iron disks) showed improvement on friction coefficient of all composites and much less wear than pure PTFE. The composites survived at contact pressures of 7 MPa, which is higher than either pure PTFE or pure ATSP could sustain. With an increase in the amount of ATSP in the composites, storage modulus, and glass transition temperature were higher, and the wear resistance was enhanced. SEM images helped provide explanations for the unusually low mean wear rates that were observed for these composite samples. Copyright © 2008 John Wiley & Sons, Ltd.
Study on a novel and efficient flame retardant synergist–nanoporous nickel phosphates VSB‐1 with intumescent flame retardants in polypropylene
Authors: Nie Shibin , Hu Yuan , Song Lei , He Shuqing , Yang Dandan
Published: May 2008

Nanoporous nickel phosphate VSB‐1 was synthesized by hydrothermal method and its structure was characterized. Then VSB‐1 was added to the ammonium polyphosphate (APP) and pentaerythritol (petol) system in a polypropylene (PP) matrix for the first time, and the synergistic effect of VSB‐1 with intumescent flame retardants (IFR) was studied. With the addition of 2 wt% VSB‐1 and 23 wt% IFR, the LOI value of PP/IFR composites increased from 28.0 to 35.5. The UL‐94 test showed that PP with 20% IFR burned and had no rating, but with the addition of 2 wt% of VSB‐1 and 18% of IFR, it could reach V‐0 rating. The results of the X‐ray photoelectron spectroscopy (XPS) showed that the ratios of P/C and N/C of PP/IFR/VSB‐1 systems changed significantly from 0.133 to 0.205 (54% increase) and from 0.0328 to 0.047 (45.4% increase), respectively under 800°C for 10 min. Compared with the organophilic montmorillonite (OMT), 4 Å zeolite, and zinc tetraborate (ZB), VSB‐1 showed better synergistic effect at the same loading. Copyright © 2008 John Wiley & Sons, Ltd.
Fabrication of highly ordered polymer/graphite flake composite with eminent anisotropic electrical property
Authors: Chen Guohua , Wang Haiquan , Zhao Weifeng
Published: May 2008

Highly ordered polyester/graphite flake composite has been fabricated via orienting the graphite flakes within a polymer matrix. The randomly dispersed graphite flakes in a polyester prepolymer were induced twice along the electric field direction, followed by the cross‐linking of the prepolymer. Scanning electron microscopy (SEM), X‐ray diffraction (XRD) analysis showed that the graphite flakes in the resulting composites were aligned parallel to each other. This structure anisotropy of the composite appeared to be a significant electrical anisotropic property with five to six orders of magnitude. Analysis showed that field‐induced torque caused by the polarization of graphite flakes undergone at electric field was a main force inducing the orientation of the graphite flakes. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis of poly(cystine bisamide)‐PEG block copolymers grafted with 1‐(3‐aminopropyl)imidazole and their phase transition behaviors
Authors: Jin Byung Suk , Kang Han Chang , Kim Dongin , Lee Kwang Hee , Bae You Han
Published: May 2008

New biodegradable and pH‐sensitive block copolymers were prepared by grafting 1‐(3‐aminopropyl) imidazole onto a backbone polymer formed via condensation polymerization between l‐cystine and EDTA‐dianhydride. The copolymer with a graft ratio of 79% exhibited a good buffering capacity and pH sensitivity. These are attributed to protonation–deprotonation of the imidazole ring at around pH 7. The copolymers with less imidazole content did not show any apparent responses to changes in pH. The particle size of the copolymer aggregate formed under basic conditions was around 200 nm and increased with decreasing pH. The critical aggregation values at pH 6.0 and 8.0, derived from the changes of intensity ratios (I1/I3) in the emission spectrums of pyrene, were approximately 0.17 and 0.05 mg/ml, respectively. The surface charge of the aggregates increased with the decreasing pH as a result of the increase in protonation of imidazole and the tertiary amine in the polymer chain. The microviscosity of hydrophobic domains was estimated using 1,6‐diphenyl‐1,3,5‐hexatriene. The decrease of the anisotropy value under acidic conditions reflects a disruption of hydrophobic interaction. Copyright © 2008 John Wiley & Sons, Ltd.
Fine dispersion of carbon black in fluorene‐based resin
Authors: Kawasaki Shinichi , Yamada Masahiro , Kobori Kana , Jin Fengzhe , Takata Toshikazu
Published: May 2008

The dispersion ability of fluorene‐based epoxy resin (FBE), bisphenol A based epoxy resin (PBE), fluorene‐based polyester (FBP), and polycarbonate (PC) in carbon black (CB) was evaluated. CB/FBE composite had a lower L value (reflectance, blackness) than that of CB/PBE composite, for the same CB content. Aggregations of CB in CB/FBE composites were much smaller than those in CB/PBE composites. The strong interaction between fluorene with cardo structure and CB resulted in a fine dispersion of CB in FBE. FBP had much higher dispersion ability of CB than PC. CB (50 wt%) was dispersed into FBP compared with the 10 wt% of CB dispersed in PC by melt blending. The effect of CB on the mechanical properties of FBP was much higher than that on PC due to fine dispersion of CB in FBP. The effect of CB addition on the Tg of FBP was also higher than that of CB on the Tg of PC. Computational simulation indicates that most stable energy between fluorene with a cardo structure and graphite structure was smaller than the energy between bisphenol A and graphite. It was also shown that the minimum energy appeared when the fluorene structure was almost parallel to the graphite plane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Physical properties of poly(trimethylene terephthalate)/organoclay nanocomposites obtained via melt compounding and in situ polymerization
Authors: Cho H.W. , Lee J.S. , Prabu A.A. , Kim K.J.
Published: May 2008

Two series of poly(trimethylene terephthalate) (PTT) nanocomposites, containing an organically modified montmorillonite (MMT) clay (1,2‐aminododecanoic acid (ADA)–intercalated MMT) were prepared via melt compounding and in situ polymerization methods using dimethyl terephthalate (DMT) and 1,3‐propanediol (PDO). The effect of different methods of preparation and varying organoclay contents (1−5 wt%) on the structural, morphological, thermal, and mechanical properties were investigated. The results of wide‐angle X‐ray diffraction (WAXD) and transmission electron microscope (TEM) suggested the possible existence of intercalation morphology between ADA‐MMT and the PTT matrix obtained from melt compounding, and mostly exfoliation state from in situ polymerization depending on the amount of organoclay. From DSC studies, in melt compounding case, the addition of ADA‐MMT in PTT increases melt‐crystallization (Tcm) peak temperature by 14−15°C irrespective of the clay content. However, the melting temperature (Tm) of pristine PTT remains unchanged with increasing clay content. In the case of in situ polymerization, the Tcm and Tm peaks are shifted towards lower temperature with increasing clay content. Dynamic mechanical thermal analysis (DMTA) studies on melt compounded samples revealed a marginal lowering of glass transition temperature (Tg) irrespective of clay content, and a noticeable decrease in Tg with increasing clay content for in situ polymerized samples. The PTT/ADA‐MMT nanocomposites via melt compounding showed higher initial modulus and yield stress, and lower strain at break compared with in situ polymerization with increasing clay content. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Study and comparison of interaction parameters and phase behavior of epoxy/polystyrene and epoxies copolymer polystyrene‐b‐poly(methyl methacrylate) blends
Authors: Torrens Francisco , Monzó Isidro S. , Gómez‐Clarí Clara M. , Abad Concepción , Campos Agustín
Published: May 2008

Thermodynamic studies in terms of phase separation behavior and interaction parameters, in mixtures of epoxy resins (thermoset materials) with thermoplastic additives, consisting of polystyrene (PS) or polystyrene‐b‐poly(methyl methacrylate) P(S‐MMA) (with small proportion of MMA), have been carried out. It can be confirmed that the solubility of P(S‐MMA) is an improvement on that of PS, with the prepolymer epoxy resins. Moreover, the interaction parameters are positive at temperatures in which phase separation is observed, but negative at temperatures in which the phase separation window disappears, in the corresponding phase diagram. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
The effect of polyoxypropylene‐montmorillonite intercalates on polymethylmethacrylate
Authors: Salahuddin Nehal
Published: May 2008

Polymethylmethacrylate (PMMA)‐layered silicate nanocomposites have been prepared by in situ polymerization of commercial type of methylmethacrylate monomer (MMA), for denture base material, into organoclay. Organoclay was prepared through an ion exchange process between sodium cations in montmorillonite and NH3+ groups in polyethertriamine hydrochloride and polyoxypropylene triamine hydrochloride with different molecular weight (5000, 440). X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the structure of the resulting composites. Both intercalated and exfoliated nanocomposites were obtained depending on the type and amount of organoclay. The thermal decomposition temperatures of the nanocomposites were found to be higher than that of pristine polymer. PMMA was strongly fixed to inorganic surfaces, due to cooperative formation of electrostatic bonding between NH3+ group and negatively charged surface of layered silicate and amide linkage between PMMA and polyethertriamine or polyoxypropylene triamine. The effect of the organoclay on the hardness, toughness, tensile stress, and elongation at break of the polymer was studied and was compared with pristine polymer. The hardness and Izod impact strength of PMMA‐organoclay nanocomposites were enhanced with the inclusion of clay. Tensile properties appear to be enhanced at certain organoclay content. However, the water absorption is slightly higher than the pristine PMMA. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Preparation of a fibrous catalyst containing palladium nanoparticles and its application in hydrogenation of olefins
Authors: Yu Jianxiang , Liu Taiqi
Published: May 2008

A novel fibrous catalyst containing palladium nanoparticles was produced via electrospinning technique. The fibrous catalyst was characterized by scanning electron microscopy and transmission electron microscopy respectively, the results show that the diameter of fiber was about 200 nm and the palladium (Pd) nanoparticles was in the range of 30–40 nm. The size and shape of Pd particles on the fiber can be adjusted by changing the concentration of polymer or amount of PdCl2 in the electrospun solution. The catalyst was tested in hydrogenation of α‐hexene and α‐octene in ethanol at room temperature. The catalytic experimental results show that the activity of the titled catalyst was 4.7 times higher than that of PdCl2/γ‐Al2O3 and higher than that of PdCl2 on poly(styrene‐divinylbenzene) resin catalyst (Zharmagambetov et al., J Mol Catal A: Chemical, 177, 165 (2001)). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Mechanisms of the homogeneous, unimolecular gas‐phase elimination kinetics of triethyl orthoacetate and triethyl orthopropionate
Authors: Marquez Edgar , Tosta Maria , Domínguez Rosa M. , Herize Armando , Chuchani Gabriel
Published: May 2008

Triethyl orthoacetate and triethyl orthopropionate were pyrolyzed in a static system over the temperature range of 291–351°C and pressure range of 80–170 Torr. The elimination reactions of these orthoesters in seasoned vessels are homogeneous, unimolecular, and follow a first‐order rate law. The reaction products are ethanol, ethylene and the corresponding ethyl ester. The Arrhenius expressions of these eliminations were found as follow: for triethyl orthoacetate, log k1 (s−1) = (13.76 ± 0.09) − (187.6 ± 1.1) kJ mol−1 (2.303 RT)−1 (r = 0.9993), and for triethyl orthopropionate, log k1 (s−1) = (13.63 ± 0.07) − (193.3 ± 1.8) kJ mol−1 (2.303 RT)−1 (r = 0.9992). A reasonable mechanism of these elimination is to consider that the COCH2CH3 bond, as Cδ+…δ− OCH2CH3 in the TS, is the rate‐determining step. The nucleophilicity of the oxygen atom of OCH2CH3 may abstract the hydrogen of the adjacent CH bond for a four‐membered cyclic structure to give the corresponding unsaturated ketal. The unstable ketal intermediate decomposes, in a six‐membered cyclic transition state, into ethylene and the corresponding ethyl ester. Copyright © 2008 John Wiley & Sons, Ltd.
Omega‐3s post‐MI: can we rely on diet to increase intake?
Authors: Thompson Angus
Published: May 2008

Angus Thompson describes the various sources of omega‐3s in the diet and over the counter and their disadvantages compared with the licensed proprietary product. Copyright © 2008 Wiley Interface Ltd
Non‐oral contraceptive options: their efficacy and suitability
Authors: Everett Marian
Published: May 2008

Many women are unaware of the wide variety of non‐oral contraceptives available and need advice on the range of options. Our Drug review considers the features and efficacy of non‐oral contraceptives, followed by sources of further information in Resources and the Datafile. Copyright © 2008 Wiley Interface Ltd
Reduction of buffer‐related current collapse in GaN FETs under favour of a field plate
Authors: Itagaki K. , Nakajima A. , Horio K.
Published: May 2008

Two‐dimensional transient analysis of GaN MESFETs with a semi‐insulating buffer layer is performed in which a deep donor and a deep acceptor are considered in the buffer layer, and the results are compared between the two cases with and without a field plate. It is shown that buffer‐related drain lag is reduced by introducing a field plate because trapping effects become smaller. It is also shown that current collapse and gate lag are also reduced in the field‐plate structure. The dependence on SiN passivation layer thickness is also studied, indicating that there is an optimum SiN thickness to minimize the buffer‐related current collapse and drain lag in GaN‐based FETs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excess As in low‐temperature grown InAs
Authors: Takushima M. , Kajikawa Y.
Published: May 2008

Using secondary ion mass spectrometry, we have investigated the excess As concentration in InAs layers grown by molecular beam epitaxy at 150‐300 °C. A step‐like increase of the As/In ratio from the substrate to the epi layer was observed for the samples grown at lower temperatures than 250 °C. The excess As concentration averaged over the grown layer thickness reached 1.2×1020 cm–3 for the layer grown at 200 °C. Through the combination with the results of X‐ray diffraction, a proportional relation of Δa⊥/a = 2×10–24 δ [As] is deduced between the perpendicular lattice mismatch Δa⊥/a and the atomic density δ [As] of excess As in the unit of cm–3. Hall effect measurements at 77 K revealed that the electron concentration is much lower than the excess As concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of the high‐energy proton irradiation on the properties of GaN ionizing radiation detectors
Authors: Kažukauskas V. , Kalendra V. , Jasiulionis R. , Vaitkus J.‐V.
Published: May 2008

Effects of the irradiation by 24 GeV protons on the properties of GaN ionizing radiation detectors were investigated. Irradiation dozes ranged from 1×1014 up to 1×1016 p/cm2. In the γ‐spectra of the samples radiation of 7Be, 22Na and other long‐living radionuclides with A < 70 was identified. Their activities were proportional to the total irradiation doses. Device contact properties were analysed by IV dependencies. Created defects were revealed by the thermally stimulated spectroscopy. In the less irradiated samples the following values of the effective thermal activation energies were found: 0.12‐0.16 eV, 0.18‐0.22 eV, 0.35‐0.42 eV and 0.84‐0.94 eV. Meanwhile in the detectors irradiated with the highest dozes only current growth with the activation energy of about 0.8‐1.0 eV could be identified. Effects of percolation transport in disordered media were proved in the irradiated material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microcavity structures in single GaAs nanowires
Authors: Hua B. , Motohisa J. , Hara S. , Fukui T.
Published: May 2008

We report the formation of Fabry‐Perot microcavity in single GaAs nanowire prepared by selective‐area metalorganic vapor phase epitaxy. The fabricated nanowires with hexagonal cross section are highly uniform and vertically oriented. Microphotoluminescence measurements of single GaAs nanowire exhibit several periodic peaks in the intensity, which are suggestive of the longitudinal modes of a Fabry‐Perot cavity. The cavity is formed along the length of the nanowire and the (111) facets of both ends act as reflecting mirrors in this case. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrogen sensors based on Pt‐AlGaN/GaN back‐to‐back Schottky diode
Authors: Wang Xinhua , Wang Xiaoliang , Xiao Hongling , Feng Chun , Wang Xiaoyan , Wang Baozhu , Yang Cuibai , Wang Junxi , Wang Cuimei , Ran Junxue , Hu Guoxin , Li Jinmin
Published: May 2008

In this paper, platinum (Pt) with a thickness of 45 nm was sputtered on the surface of AlGaN/GaN heterostructure to form the Schottky contact and the back‐to‐back Schottky diodes were characterized for H2 sensing at room temperature. Both the forward and reverse current of the devices increased with exposure to H2 gas, which was attributed to Schottky barrier height reduction caused by hydrogen absorption in the catalytic metals. A shift of 0.7 V at 297 K was obtained at a fixed forward current of 0.1 mA after switching from N2 to 40% H2 in N2. The sensor's responses under different concentrations from 2500 ppm H2 to 40% H2 in N2 at 297 K were investigated. Time response of the sensor at a fixed bias of 1 V was given. Finally, the decrease of the Schottky barrier height and the sensitivity of the sensor were calculated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Device characteristics of back channel‐modified organic thin‐film transistors
Authors: Hoshino S. , Suemori K. , Yoshida M. , Uemura S. , Kodzasa T. , Takada N. , Kamata T.
Published: May 2008

Influence of back‐channel electronic state on device characteristics was investigated for pentacene‐based thin‐film transistors (TFTs), where top surface of the semiconductor layer was covered with an LiF thin film. We observed higher field‐effect hole mobility in the TFTs with the LiF‐covered back channel than in the corresponding uncovered counterparts. In addition, the LiF‐covered TFTs exhibited a decrease in turn‐on voltages and an increase in off‐state current depending on the thickness of the LiF layer and top‐ or bottom‐contact configuration of the source and drain electrodes. We attributed the electronic effect brought about by the LiF coating to a downward band bending in the back channel originating from a rearrangement of the electronic energy‐level alignment at the pentacene/LiF interface. The difference in the device characteristics from those of the uncovered TFTs was successfully explained by such electronic processes in the pentacene layer induced by the downward band bending in the back channel as a pseudo ‐back gate effect and generation of offsetting holes against the surface electronegativity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polycrystallization phenomena of organic alloy and multilayer structures on naphthyl‐substituted diamine‐based hole transport layer for organic light‐emitting diode
Authors: Mori T. , Iida Y.
Published: May 2008

We demonstrated the polycrystallization process of N,N'‐di(1‐naphthyl)‐N,N'‐diphenyl‐1,1'‐diphenyl‐1,4'‐diamine (NPD) and N,N'‐diphenyl‐N,N'‐bis(3‐methylphenyl)‐1,1'‐diphenyl‐4,4'‐diamine (TPD), which is well known as a hole transport material, and the availability of the organic alloy method fabricated by co‐evaporation method. We fabricated multi‐layer structure of NPD and TPD: especially bilayer as a basic and typical structure. One is TPD layer on NPD layer (T/N specimen) and the other is NPD layer on TPD layer (N/T specimen). The polycrystallization of bilayer structure specimens is suppressed as compared with organic NPD:TPD=1:1 alloy specimen. Especially the T/N specimen is found to be stable in an amorphous region. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of the unintentional incorporation of Al during the molecular beam epitaxial growth of GaInNAs quantum well
Authors: Wu S. D. , Kato M. , Uchiyama M. , Higashi K. , Ishikawa F. , Kondow M.
Published: May 2008

We report the effect of unintentional Al incorporation during the growth of GaInNAs/GaAs quantum well (QW) by molecular beam epitaxy (MBE). The effect of extrinsic Al is investigated by secondary ion mass spectrometry. QW grown directly on AlAs layer shows unintentionally incorporated Al with its concentration as high as 1×1018 cm–3, resulting in degraded PL intensity. In order to prevent the Al incorporation, we grow QW without heating up Al source after leaving the MBE chamber within As atmosphere for a long period. The concentration of the extrinsic Al becomes lower than 2×1016 cm–3, leading to a strong PL intensity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of minority carrier lifetime for InAlAs/InGaAs high electron mobility transistors by using 1.55‐μm femto‐second pulse laser
Authors: Taguchi Hirohisa , Sano Chihiro , Murakami Hiroaki , Oura Masashi , Iida Tsutomu , Takanashi Yoshifumi
Published: May 2008

The minority carrier lifetime (τ) of High electron mobility transistors (HEMTs) made using the InAlAs/InGaAs material system lattice‐matched to the InP substrate had been obtained from optical response measurements with a 1.55‐μm femto‐second pulse laser where the laser was illuminated onto the backside of a wafer. The drain current of HEMTs associated with the optical pulse was detected using a digitizing oscilloscope, and τ was estimated from the exponential dependence of drain current on time. In our current investigation, we found that τ is dominated by the following modes: (1) the amount of time required for holes to transit across the channel toward the source, and (2) the amount of time required for the holes accumulated in the source region to recombine with two‐dimensional electron gas (2DEG) through the Auger mechanism. Because the sheet concentration (ps) of holes accumulated in source region is low at a low source‐to‐drain voltage (VDS), Auger recombination is not predominant, and τ was only dominated by the hole transit time. At a high VDS, ps became high enough for Auger recombination to occur and dominate τ. Furthermore, we investigated the optical power dependence of τ where the optical power was supplied in a continuous wave (CW) to generate photo‐excited holes in a steady state. The value of τ decreased monotonically as VDS increased and saturated in as little as 6x10–10 s when the optical power was increased. The theoretical investigation was made to understand this saturation phenomenon. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bistability operation of photocurrent due to wave‐function coupling of Wannier‐Stark localization states in a GaAs/AlAs superlattice
Authors: Hasegawa T. , Nakayama M.
Published: May 2008

We have investigated effects of the resonant wave‐function coupling between Wannier‐Stark localization states on photocurrent properties in a GaAs (6.8 nm)/Al0.1Ga0.9As (4.0 nm) superlattice. The resonant coupling, which causes an anticrossing behavior of the relevant transition energies, were clearly detected by electroreflectance spectroscopy and analyzed by calculating the Wannier‐Stark localization states as a function of electric field strength. It is found that the photocurrent‐voltage characteristics exhibit a peak structure, which results in a negative differential resistance, owing to a change of the optical transition probability under the resonant‐coupling condition between the first and second quantized electron states in adjacent quantum wells. Utilizing this negative differential resistance property, we have demonstrated a photocurrent‐bistability operation of a self‐electro‐optic effect device. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectrally selective organic photodiodes
Authors: Lamprecht B. , Thünauer R. , Köstler S. , Jakopic G. , Leising G. , Krenn J. R.
Published: May 2008

We report on the fabrication of spectrally selective organic photodiodes (OPDs) and present a green sensitive OPD, whose spectral response peaks in the green region between 470 nm and 560 nm, as well as a red sensitive OPD whose spectral response peaks in the red region between 610 nm to 720 nm. We show that the spectral sensitivity of OPDs can be tuned by either choosing organic semiconductors with the appropriate photoresponse or by utilizing adequate device architectures with integrated optical filters. The results demonstrate the great flexibility of organic semiconductor materials. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct and Indirect Quantum Mechanical QSPR Hildebrand Solubility Parameter Models
Authors: Code James E. , Holder Andrew J. , Eick J. David
Published: May 2008

The objectives of this study were to develop Quantitative Structure–Property Relationship (QSPR) models to predict Hildebrand solubility parameters (δt). The study investigated direct δt prediction by QSPR and indirect δt calculation from QSPR‐predicted enthalpy of vaporization values. Molecular ground‐state minimum energy conformations were identified and optimized using the AM1 semiempirical Quantum Mechanical (QM) method. Predictive multiple linear regression models were derived correlating training set experimental solubility parameters or enthalpies of vaporization with descriptors obtained from the QM calculations. A four‐descriptor Hildebrand total solubility parameter regression equation was developed where R2=0.97, R$\rm{ {_{adj}^{2}}}$=0.97, F=461.5, s2=0.53, and Root Mean Square Error (RMSE)=0.69. A four‐descriptor QSPR model to predict enthalpies of vaporization (ΔHvap−kJ/mol) was constructed where R2=0.96, R$\rm{ {_{adj}^{2}}}$=0.96, F=230.3, s2=4.75, and RMSE=2.04. δt calculations from ΔHvap correlated well with literature δt , where R2=0.96. Both of these models are statistically significant as well as predictive. The direct and indirect δt models developed here compare favorably with liquid solubility parameter estimation accuracies (10%) reported by Hoftyzer–Van Krevelen and Hoy. These methods are useful for determining the miscibility of small organic molecules, an important consideration when formulating polymer blends.
Rapid classification of perfumes by extractive electrospray ionization mass spectrometry (EESI‐MS)
Authors: Chingin Konstantin , Gamez Gerardo , Chen Huanwen , Zhu Liang , Zenobi Renato
Published: May 2008

Extractive electrospray ionization mass spectrometry (EESI‐MS) was applied to rapid fingerprinting of various perfumes for quality classification. Unique EESI‐MS fingerprints of ten famous brands were obtained. This technique was shown to be applicable to rapid forgery detection on the example of an authentic and a counterfeit ‘Miss Dior’ fragrance by Christian Dior. We believe that the high throughput and simplicity of this sample‐preparation‐free method can be advantageous in the perfume industry, for instance when applied to online quality control. Copyright © 2008 John Wiley & Sons, Ltd.
Measuring Epstein–Barr virus (EBV) load: the significance and application for each EBV‐associated disease
Authors: Kimura Hiroshi , Ito Yoshinori , Suzuki Ritsuro , Nishiyama Yukihiro
Published: May 2008

Because Epstein–Barr virus (EBV) is ubiquitous and persists latently in lymphocytes, simply detecting EBV is insufficient to diagnose EBV‐associated diseases. Therefore, measuring the EBV load is necessary to diagnose EBV‐associated diseases and to explore EBV pathogenesis. Due to the diverse biology of EBV, the significance of measuring EBV DNA and the optimal type of specimen differ among EBV‐associated diseases. Recent advances in molecular technology have enabled the EBV genome to be quantitated rapidly and accurately. Real‐time polymerase chain reaction (PCR) is a rapid and reliable method to quantify DNA and is widely used not only as a diagnostic tool, but also as a management tool for EBV‐associated diseases. However, each laboratory currently measures EBV load with its own “homebrew” system, and there is no consensus on sample type, sample preparation protocol, or assay units. The EBV real‐time PCR assay system must be standardised for large‐scale studies and international comparisons. Copyright © 2008 John Wiley & Sons, Ltd.
Apolipoprotein E4 domain interaction: Synaptic and cognitive deficits in mice
Authors: Zhong Ning , Scearce‐Levie Kimberly , Ramaswamy Gayathri , Weisgraber Karl H.
Published: May 2008

Background

Apolipoprotein E4 (apoE4), the major genetic risk factor for Alzheimer's disease (AD) and other neurodegenerative diseases, has three structural and biophysical properties that distinguish it from the other isoforms—domain interaction, reduced stability, and lack of cysteine. Assessing their relative contributions to effects of apoE4‐associated pathogenesis in AD is important from a mechanistic and therapeutic perspective, that is not possible using human apoE transgene or knock‐in models.

Methods

We analyzed Arg‐61 apoE mice, a gene‐targeted model that selectively displays domain interaction.

Results

The mice displayed age‐dependent loss of the synaptic protein synaptophysin in neocortex and hippocampus and had lower levels of the postsynaptic neuroligin‐1. Activation of dentate gyrus granule neurons increased Arc expression 3.5‐fold in wildtype mice but only 2.3‐fold in Arg‐61 mice. The losses of synaptic proteins caused a mild memory deficit in Arg‐61 mice in the water‐maze test. Since synaptic integrity requires efficient glutamate uptake, we measured astrocyte glutamate transporter 1 in the hippocampus. The level was reduced in Arg‐61 mice, suggesting that inefficient glutamate uptake by astrocytes causes chronic excitotoxicity. Consistent with the reduced secretion of Arg‐61 apoE by astrocytes in this model, cholesterol secretion was also reduced 34%. This reduction could also contribute to the synaptic deficits by limiting the availability of cholesterol for neuronal repair.

Conclusions

Domain interaction in the absence of other structural characteristics of apoE4 is sufficient to cause synaptic pathology and functional synaptic deficits, potentially associated with astrocyte dysfunction and impaired maintenance of neurons. Therapeutic targeting of domain interaction might blunt effects of apoE4 in neurodegenerative disease.
Localised Mycobacterium ulcerans infection in a cat in Australia
Authors: Elsner Lisa , Wayne Julie , O'Brien Carolyn R. , McCowan Christina , Malik Richard , Hayman John A. , Globan Maria , Lavender Caroline J. , Fyfe Janet A.
Published: May 2008

A 10-year-old castrated male domestic cat domiciled in eastern Victoria (Australia) was presented for a subcutaneous mass on its nasal bridge in November 2006. Cytological examination of an aspirate demonstrated pyogranulomatous inflammation. At surgery, the lesion consisted of an encapsulated mass containing viscid fluid. Histological examination of the resected lesion revealed pyogranulomatous inflammation surrounding a central zone of necrosis. Sections stained with the Ziehl–Neelsen method revealed numerous acid-fast bacilli, intracellularly within macrophages and extracellularly. Molecular studies established the infection was caused by Mycobacterium ulcerans. As histology demonstrated that the infection extended to the margin of the excised tissues, the cat was treated subsequently with clarithromycin (62.5 mg orally once daily for 7 days, then twice daily for 3 months). The surgical wound healed unremarkably. The infection has not recurred at the time of writing, 1 year following discontinuation of treatment. Although M ulcerans infections have been recorded in variety of mammals, this is the first known case in a cat.
Toward a Directed Benevolent Market Polity: Rethinking Medical Morality in Transitional China
Authors: FAN RUIPING
Published: May 2008

Healthcare systems in Singapore, Hong Kong, and mainland China are strikingly distinct from those in the West. Economically speaking, each of the aforementioned Eastern systems relies in great measure on private expenditures supplemented by savings accounts. Western nations, on the other hand, typically exhibit government funding and wariness about healthcare savings accounts. This essay argues that these and other differences between Pacific Rim healthcare systems and Western systems should be assessed in light of background Confucian commitments operating in the former. In the Confucian context, bioethics and healthcare policy have a unique content, texture, and set of implications that often affront Western assumptions about the appropriate individual autonomy of patients and the appropriate character of social safety nets for healthcare.
Sex Selection by Preimplantation Genetic Diagnosis (PGD) for Nonmedical Reasons in Contemporary Israeli Regulations
Authors: GRAZI RICHARD V. , WOLOWELSKY JOEL B. , KRIEGER DAVID J.
Published: May 2008

We report here on recent developments in Israel on the issue of sex selection for nonmedical reasons by preimplantation genetic diagnosis (PGD). Sex selection for medical reasons (such as in cases of sex-linked genetic diseases) is generally viewed as uncontroversial and legal in European and American law. Its use for nonmedical reasons (like “balancing” the gender ratio in a family) is generally illegal in European countries. In the United States, it is not illegal, although in the opinion of the Ethics Committee of the American Society for Reproductive Medicine (ASRM), it is problematic. This position is undergoing reconsideration, albeit in a limited way.