bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in hydrology and sediment delivery of the Mekong River in the last 50 years: connection to damming, monsoon, and ENSO
Authors: Xue Zuo , Liu J. Paul , Ge Qian
Published: June 2010

As the population and economy boom, more and more dams are being built in the Mekong River basin. Previous studies have revealed that Manwan Dam had little influence on the runoff–SSC (suspended sediment concentration) relationship, and the sediment load was relatively stable over the past 40 years. However, little is known at present on the relationship among monsoons, El Niño Southern Oscillation (ENSO), precipitation, runoff, and the impact of dams on the delta dynamics. A comprehensive hydropower GIS database covering the entire Mekong basin is presented in this study. Mann–Kendall trend analysis showed no significant change in precipitation and runoff over the past 50 years. Spectral analysis showed that the runoffs of the middle to lower reach of Mekong River are correlated with the Indian Monsoon, where as the East Asian Monsoon's influence is mainly on the lower reach. With another 200 new dams to be added to the basin in the next couple of decades, changes are expected in both hydrological regime and delta dynamics. On one hand, the runoff showed a closer connection with the regional precipitation and ENSO in the post‐dam period (1993–2005) than in the pre‐dam period (1950–1993). Such a relationship is expected to be even closer when more dams are completed. On the other hand, both daily maximum and minimum water levels on the delta plain have shown an abrupt drop since the end of 1994. This reduced water‐level gradient between the river and sea inevitably weakens the sediment discharge to the coast, which might intensify the ongoing coastal erosion on the eastern part of the delta plain. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of secondary metabolites on gall fly infestation of mango leaves
Authors: Augustyn W. A. , Botha B. M. , Combrinck S. , Maree J. E. , du Plooy G. W.
Published: June 2010

The mango gall fly (Procontarinia) is a growing concern in many countries that import mango trees. Mangoes flush (produce opening buds) twice a year: once in spring, and the main flush, which occurs in early autumn flush and corresponds to the photoperiod necessary for the gall fly to emerge. Gall flies attack only very young mango flush leaves. Three cultivars displaying varying susceptibility were used in this study: Heidi, which typically is heavily infected; Keitt, which displays antixenosis properties; and Sensation, which is resistant to gall fly attack. Headspace profiles of the three cultivars were obtained over two full growing seasons. It was found that flush leaves emit higher levels of volatile organic compounds than mature leaves. Volatile emissions peaked during the main flush, after which they declined as the tree went into the winter dormant period. The levels of α‐ and β‐pinene increased in gall fly‐susceptible cultivars as the season progressed, while very low levels of these terpenes were emitted by resistant cultivars. The changes in the profiles of these emissions suggest that α‐ and β‐pinene may be linked to gall fly susceptibility. In addition, chemometric analysis confirmed the correlation between volatile emissions and gall fly susceptibility. Copyright © 2010 John Wiley & Sons, Ltd.
The effect of market reforms and new public management mechanisms on the Swiss health care system
Authors: Moresi‐Izzo Stefania , Bankauskaite Vaida , Gericke Christian A.
Published: June 2010

In 1996, the Federal Law on Health Insurance (LAMal) was adopted in order to contain costs in Swiss health care. At the same time, the reform aimed to maintain or even improve solidarity and encourage institutional reform through new public management (NPM) and market mechanisms. More freedom in contractual conditions between insurers and providers and a clearer distinction of responsibilities between federal and regional (cantonal) authorities were stipulated to achieve efficiency, effectiveness, and transparency. The focus of this paper is an analysis of the effects of market reforms and NPM mechanisms introduced with the LAMal on the cost‐containment, quality of care and equity objectives in the Swiss health care system. Copyright © 2010 John Wiley & Sons, Ltd.
Early Nascent Chain Folding Events on the Ribosome
Authors: Cabrita Lisa D. , Dobson Christopher M. , Christodoulou John
Published: June 2010

To maintain optimal protein homeostasis within the cell, a complex interplay exists between factors determining the production, transport, and folding of nascent chains. Here we review the evidence for the structural and dynamical properties of nascent polypeptide chains as they emerge from the ribosome and that enable them to acquire their biologically active, three‐dimensional structures. In particular, we focus on the application of NMR spectroscopy, which is now emerging as a powerful technique to probe the behavior and properties of emerging nascent chains.
Molecular basis of cytokine receptor activation
Authors: Lopez Angel F , Hercus Timothy R , Ekert Paul , Littler Dene R , Guthridge Mark , Thomas Daniel , Ramshaw Hayley S , Stomski Frank , Perugini Michelle , D'Andrea Richard , Grimbaldeston Michele , Parker Michael W
Published: June 2010

Cytokines are secreted soluble peptides that precisely regulate multiple cellular functions. Amongst these the GM‐CSF/IL‐3/IL‐5 family of cytokines controls whether hematopoietic cells will survive or apoptose, proliferate, differentiate, migrate, or perform effector functions such as phagocytosis or reactive oxygen species release. Their potent and pleiotropic activities are mediated through binding to high affinity membrane receptors at surprisingly low numbers per cell. Receptor binding triggers a cascade of intracellular signaling events, including reversible phosphorylation of receptor subunits and associated signaling molecules, leading to multiple biological responses, with the prevention of apoptosis or “cell survival” being a key cellular function that underpins all others. Many chronic inflammatory diseases and a number of haematological malignancies are driven by deregulated GM‐CSF, IL‐3, or IL‐5 cytokine receptor signaling, highlighting their importance in disease. A major step in understanding how these cytokine receptors function is to elucidate their three dimensional structure and to relate this to the many signaling pathways emanating from their receptors. We have recently solved the structure of the human GM‐CSF receptor complexed to GM‐CSF which revealed distinct forms of receptor assembly: a hexamer that comprises two molecules each of GM‐CSF, GM‐CSF receptor alpha chain and GM‐CSF receptor beta chain; and an unexpected dodecamer in which two hexameric complexes associate through a novel site 4. This latter form is necessary to bring JAK2 molecules sufficiently close together to enable full receptor activation. In this review we focus on the most recent insights in cytokine receptor signaling, and in receptor assembly. The stage is now set to link distinct forms of cytokine receptor assembled structures to specific forms of cytokine receptor signaling and function. Armed with this knowledge it may be possible to map distinct cytokine receptor signaling pathways from the cell surface to the cell nucleus which may themselves become new therapeutic targets. © 2010 IUBMB IUBMB Life, 62(7): 509–518, 2010
Photocrosslinkable chitosan modified with angiopoietin‐1 peptide, QHREDGS, promotes survival of neonatal rat heart cells
Authors: Rask Fiona , Dallabrida Susan M. , Ismail Nesreen S. , Amoozgar Zohreh , Yeo Yoon , Rupnick Maria A. , Radisic Milica
Published: June 2010

Myocardial infarction (MI) results in the death of cardiomyocytes (CM), which causes scar formation and pathological remodeling of the heart. The delivery of healthy myocytes or bone marrow cells reduces pathological remodeling after MI, however, current cell injection methods have low cell survival rates and high cell loss. The main objective of this work was to develop a novel hydrogel that can promote survival of CMs. Photocrosslinkable azidobenzoic acid modified chitosan (Az‐chitosan) was conjugated with the angiopoietin‐1‐derived peptide, QHREDGS. This novel peptide is thought to mediate attachment and survival responses of CM to angiopoietin‐1 via integrin binding. Thin layers of Az‐chitosan, Az‐chitosan‐QHREDGS, and Az‐chitosan‐DGQESHR (scrambled peptide control) were spin coated on glass slides and photocrosslinked with application of UV light (365 nm). Neonatal rat heart cells cultured up to 5 days, demonstrated significantly higher attachment and viability on Az‐chitosan‐QHREDGS compared to cells on other hydrogel controls. Surfaces were also stained for the CM‐specific marker troponin I, demonstrating significantly higher percentage of CMs on Az‐chitosan‐QHREDGS compared to Az‐chitosan. The cells cultivated on Az‐chitosan‐QHREDGS demonstrated significantly lower levels of caspase 3/7 activation after taxol treatment in comparison to cells cultivated on the control hydrogels, glass substrate, or Az‐chitosan linked to RGD, an established integrin binding peptide that did not protect against apoptosis. Thus, Az‐chitosan‐QHREDGS supports attachment and survival of neonatal rat heart cells. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. II. In vitro and in vivo biological evaluation
Authors: Fu Qiang , Rahaman Mohamed N. , Bal B. Sonny , Bonewald Lynda F. , Kuroki Keiichi , Brown Roger F.
Published: June 2010

In Part I, the in vitro degradation of bioactive glass scaffolds with a microstructure similar to that of human trabecular bone, but with three different compositions, was investigated as a function of immersion time in a simulated body fluid. The glasses consisted of a silicate (13‐93) composition, a borosilicate composition (designated 13‐93B1), and a borate composition (13‐93B3), in which one‐third or all of the SiO2 content of 13‐93 was replaced by B2O3, respectively. This work is an extension of Part I, to investigate the effect of the glass composition on the in vitro response of osteogenic MLO‐A5 cells to these scaffolds, and on the ability of the scaffolds to support tissue infiltration in a rat subcutaneous implantation model. The results of assays for cell viability and alkaline phosphatase activity showed that the slower degrading silicate 13‐93 and borosilicate 13‐93B1 scaffolds were far better than the borate 13‐93B3 scaffolds in supporting cell proliferation and function. However, all three groups of scaffolds showed the ability to support tissue infiltration in vivo after implantation for 6 weeks. The results indicate that the required bioactivity and degradation rate may be achieved by substituting an appropriate amount of SiO2 in 13‐93 glass with B2O3, and that these trabecular glass scaffolds could serve as substrates for the repair and regeneration of contained bone defects. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Gold nanoparticles on titanium and interaction with prototype protein
Authors: Padmos J. Daniel , Duchesne Paul , Dunbar Michael , Zhang Peng
Published: June 2010

Modifying titanium (Ti) implant surfaces with functional proteins can strengthen the interface between prosthesis and bone. A prototype system was developed using gold nanoparticles (AuNPs) to immobilize proteins onto Ti. An electroless (galvanic displacement) deposition method was first used to form AuNPs of controlled size and coverage on commercial Ti foil (giving Ti‐AuNPs). Parameters were then modified to create two groups of discs (n = 26) with different average AuNP diameters. Scanning electron microscopy and X‐ray photoelectron spectroscopy were used to characterize the morphology and surface structure of Ti‐AuNPs. To study the interaction of Ti‐AuNPs with proteins, Ti discs (n = 8) modified with plain AuNPs and discs (n = 8) modified with thiol (HSRCOOH)‐functionalized AuNPs were treated with lysozyme solution. The amount and activity of the lysozyme on the discs were examined with Micro‐BCA and enzymatic assays. Lysozyme was immobilized onto the discs, and the assays showed that the discs with thiol‐functionalized AuNPs, discs with bare AuNPs, and Ti controls had average lysozyme adsorptions of 23 × 104, 2.3 × 104, and 5.7 × 104 μg/m2, respectively. The activity assays showed that 21.5, 18.4, and 12.5% of the adsorbed lysozyme was active on the discs with thiol‐functionalized AuNPs, discs with bare AuNPs, and Ti controls, respectively. This technique holds promise for binding functional biomolecules to surgical implants, hence possibly creating implant surfaces that react to their local environment. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Directional fluid flow enhancesin vitroperiosteal tissue growth and chondrogenesis on poly‐ε‐caprolactone scaffolds
Authors: Tarng Yih‐Wen , Casper Michelle E. , Fitzsimmons James S. , Stone James J. , Bekkers Joris , An Kai‐Nan , Su Fong‐Chin , O'Driscoll Shawn W. , Reinholz Gregory G.
Published: June 2010

The purpose of this study was to investigate the effect of directional fluid flow on periosteal chondrogenesis. Periosteal explants were harvested from 2‐month‐old rabbits and sutured onto poly‐ε‐caprolactone (PCL) scaffolds with the cambium layer facing away from the scaffolds. The periosteum/PCL composites were cultured in suspension in spinner flask bioreactors and exposed to various fluid flow velocities: 0, 20, 60, and 150 rpm for 4 h each day for 6 weeks. The application of fluid flow significantly increased percent cartilage yield in periosteal explants from 17% in the static controls to 65–75% under fluid flow (there was no significant difference between 20, 60, or 150 rpm). The size of the neocartilage was also significantly greater in explants exposed to fluid flow compared with static culture. The development of zonal organization within the engineered cartilage was observed predominantly in the tissue exposed to flow conditions. The Young's modulus of the engineered cartilage exposed to 60 rpm was significantly greater than the samples exposed to 150 and 20 rpm. These results demonstrate that application of directional fluid flow to periosteal explants secured onto PCL scaffolds enhances cell proliferation, chondrogenic differentiation, and cell organization and alters the biomechanical properties of the engineered cartilage. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.
Petroleum‐contaminated soil remediation in a new solid phase bioreactor
Authors: Rizzo Andrea C. de L. , dos Santos Renata da Matta , dos Santos Ronaldo L. C. , Soriano Adriana U. , da Cunha Cláudia D. , Rosado Alexandre S. , Sobral Luis G. dos S. , Leite Selma G. F.
Published: June 2010

BACKGROUND: Oil spills are a frequent source of environmental contamination. As a consequence, remediation of soils, waters and sediments is a great challenge in this area of research. This study aims at using a new type of soil bioreactor (13 L bench‐scale and 800 L pilot‐scale) to treat tropical soil contaminated with petroleum. Additionally, it includes the evaluation of the effectiveness of two auxiliary techniques: bulking agent addition (sawdust) and biostimulation using two different nitrogen sources (sodium nitrate and urea).

RESULTS: The best result in bench‐ and pilot‐scale bioreactors were reached when using urea as a nitrogen supplement and bulking agent addition. Removal of 20 to 35% of total petroleum hydrocarbon (TPH) was achieved within 42 days. The molecular fingerprinting performed with 16S‐PCR analysis associated with denaturing gradient gel electrophoresis (DGGE) was used to evaluate changes in the pattern of the bacterial community for all experimental conditions tested. The results revealed that the use of urea caused a smaller change in the dominant bacterial community structure than the treatments using nitrate, showing that this analysis can be a useful complementary tool to evaluate the impact of treatment strategies applied to hydrocarbon‐contaminated soil.

CONCLUSIONS: These new solid phase bioreactors showed satisfactory results in the tropical soil bioremediation process, proving that the homogenization system interferes with crude oil biodegradation efficiency. This new technology can be used as an isolated treatment as well as in association with other classically employed bioremediation technologies. Copyright © 2010 Society of Chemical Industry
Monitoring and evaluation in global HIV/AIDS control—weighing incentives and disincentives for coordination among global and local actors
Authors: Holzscheiter Anna , Walt Gill , Brugha Ruairi
Published: June 2010

This paper discusses coordination efforts of both donors and recipient countries in the monitoring and evaluation (M&E) of health outcomes in the field of HIV/AIDS. The coordination of M&E is a much underdeveloped area in HIV/AIDS programming in which, however, important first steps towards better synchronisation have already been taken. In this paper, we review the concepts and meanings commonly applied to M&E, and approaches and strategies for better coordination of M&E in the field of HIV/AIDS. Most importantly, drawing on this analysis, we examine why the present structure of global health governance in this area is not creating strong enough incentives for effective coordination among global and local actors. Copyright © 2010 John Wiley & Sons, Ltd.
Circulating plastic adherent mesenchymal stem cells in aged hip fracture patients
Authors: Alm Jessica J. , Koivu Helka M.A. , Heino Terhi J. , Hentunen Teuvo A. , Laitinen Saara , Aro Hannu T.
Published: June 2010

We examined the presence of circulating plastic adherent multipotent mesenchymal stem cells (MSCs) in fracture patients. Three patient groups (n = 10–18) were evaluated, including elderly females with a femoral neck fracture treated with cemented hemiarthroplasty, an age‐ and sex‐matched group with hip osteoarthritis (OA) treated with cemented total hip arthroplasty (THA), and younger adults with surgically treated lower extremity fractures. The presence of circulating MSCs pre‐ and postoperatively was compared to bone marrow (BM) MSCs from the same subjects. Criteria for identifying MSCs included cell surface markers (CD105+, CD73+, CD90+, CD45−, CD14−), proliferation through several passages as well as osteogenic, chondrogenic, and adipogenic differentiation. Plastic adherent MSCs were found in peripheral blood (PB) from 22% of hip fracture patients, 46% of younger fracture patients, and in none of 63 pre‐ and postmenopausal women with hip OA. When detectable, circulating MSCs appeared between 39 and 101 h after fracture. PB derived MSCs did not differ from BM derived MSCs, except for a small population (<15%) of CD34+ cells among PB derived MSCs. This initial study indicates mobilization of MSCs into the circulation in response to fracture, even in very old patients, while circulating MSCs were not detectable before or after elective THA. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1634–1642, 2010
Economic valuation of land restoration: The case of exclosures established on communal grazing lands in Tigray, Ethiopia
Authors: Mekuria W. , Veldkamp E. , Tilahun M. , Olschewski R.
Published: June 2010

Converting degraded grazing lands into exclosures is one option to restore soil nutrients and to sequester carbon from the atmosphere. We estimate the economic value of such a conversion and assess the perception of local communities concerning exclosures in the highlands of Tigray, Ethiopia. Our research combines a soil and vegetation study with a socio‐economic survey, and a financial analysis. Over a period of 30 years, sequestered carbon dioxide was 246 Mg ha−1, total soil nitrogen increased by 7·9 Mg ha−1 and additional available phosphorous stocks amounted to 40 kg ha−1. The Net Present Value of exclosure's ecosystem services under consideration was about 28 per cent (837 US $) higher than alternative wheat production. Carbon revenues alone added up to only about 44 per cent of the net revenues of wheat production. This indicates that (i) carbon market revenues only, would not generate sufficient incentives to establish additional exclosures, and (ii) if all benefits are taken into account and financially rewarded, exclosures are competitive to alternatives land uses. We also identified substantial opportunities to mobilize the local communities in efforts to establish exclosures, given that more than 75 per cent had a positive view on exclosures effectiveness to restore degraded soils and vegetation. We conclude that a comprehensive analysis is necessary to consider the ecological as well as economic and social impacts of exclosures. Our findings are important information for local decision makers and may provide incentives for the establishment of further exclosures in the Northern Highlands of Ethiopia, thereby contributing to a sustainable local development process. Copyright © 2010 John Wiley & Sons, Ltd.
Bolus ingestion of white and green tea increases the concentration of several flavan‐3‐ols in plasma, but does not affect markers of oxidative stress in healthy non‐smokers
Authors: Müller Nadine , Ellinger Sabine , Alteheld Birgit , Ulrich‐Merzenich Gudrun , Berthold Heiner K. , Vetter Hans , Stehle Peter
Published: June 2010

White tea (WT) is rich in flavan‐3‐ols as green tea (GT) and might provide health protective effects due to the strong antioxidant properties of flavan‐3‐ols. Since intervention studies with WT are lacking, we evaluated the effects of WT consumption on antioxidant status, antioxidant capacity and biomarkers of oxidative stress compared to water and GT. After an overnight fast, 70 healthy non‐smokers were randomized to consume 600 mL of WT, GT or water (control). Plasma (epi‐)catechin and epi(gallo)catechingallate, antioxidant capacity (Folin assay, trolox equivalent antioxidant capacity test), 8‐iso‐prostaglandin F2α, ascorbic acid and uric acid were determined before and several times within 8 h after consumption. DNA strand breaks were measured in vivo and ex vivo (H2O2 stimulation) in leukocytes. Plasma flavan‐3‐ols significantly increased after WT and GT ingestion. Trolox equivalent antioxidant capacity was lower after 5 h in controls versus WT (p=0.031) and GT (p=0.005). Folin‐Ciocalteu reducing capacity, ascorbic and uric acid as well as markers of oxidative stress (8‐iso‐prostaglandin‐F2α, DNA strand breaks) were not affected by the beverages. A short‐term increase of catechins does not change plasma antioxidant capacity in healthy subjects. Conclusions with respect to health protective effects of WT and GT on the basis of these biomarkers can, thus, not be drawn.
Nonextractable polyphenols, usually ignored, are the major part of dietary polyphenols: A study on the Spanish diet
Authors: Arranz Sara , Silván Jose Manuel , Saura‐Calixto Fulgencio
Published: June 2010

Scope: Dietary polyphenols (PP) can be divided into two groups: extractable polyphenols (EPP) or compounds solubilized by aqueous organic solvents, and nonextractable polyphenols (NEPP) or compounds that remain in their corresponding extraction residues. Most studies on food polyphenols and dietary intakes address exclusively EPP. The objective of this work was to determine the actual amount of PP, including NEPP, in food and in a whole diet.

Methods and results: HPLC‐MS analyses were performed to identify EPP in methanol–acetone extracts and NEPP in the acidic hydrolyzates of their extraction residues in cereals, fruits, vegetables, nuts, and legumes. NEPP contents, estimated as hydrolyzable PP plus nonextractable proanthocyanidins (PA), ranged from 880 mg/100 g dry weight in fruits to 210 mg/100 g in cereals and were substantially higher than the contents of EPP. NEPP intake (day/person) in the Spanish diet (942 mg) is higher than EPP intake (258 mg) fruits and vegetables (746 mg) are the major contributors to the total PP intake (1201 mg).

Conclusion: Non extractable polyphenols are the major part of dietary polyphenols. The knowledge of intakes and physiological properties of NEPP may be useful for a better understanding of the potential health effects of dietary PP.
Diosgenin present in fenugreek improves glucose metabolism by promoting adipocyte differentiation and inhibiting inflammation in adipose tissues
Authors: Uemura Taku , Hirai Shizuka , Mizoguchi Noriko , Goto Tsuyoshi , Lee Joo‐Yong , Taketani Keiko , Nakano Yuki , Shono Jinji , Hoshino Shohei , Tsuge Nobuaki , Narukami Toshihiko , Takahashi Nobuyuki , Kawada Teruo
Published: June 2010

In obesity, adipocyte hypertrophy and chronic inflammation in adipose tissues cause insulin resistance and type‐2 diabetes. Trigonella foenum‐graecum (fenugreek) can ameliorate hyperglycemia and diabetes. However, the effects of fenugreek on adipocyte size and inflammation in adipose tissues have not been demonstrated. In this study, we determined the effects of fenugreek on adipocyte size and inflammation in adipose tissues in diabetic obese KK‐Ay mice, and identified the active substance in fenugreek. Treatment of KK‐Ay mice with a high fat diet supplemented with 2% fenugreek ameliorated diabetes. Moreover, fenugreek miniaturized the adipocytes and increased the mRNA expression levels of differentiation‐related genes in adipose tissues. Fenugreek also inhibited macrophage infiltration into adipose tissues and decreased the mRNA expression levels of inflammatory genes. In addition, we identified diosgenin, a major aglycone of saponins in fenugreek to promote adipocyte differentiation and to inhibit expressions of several molecular candidates associated with inflammation in 3T3‐L1 cells. These results suggest that fenugreek ameliorated diabetes by promoting adipocyte differentiation and inhibiting inflammation in adipose tissues, and its effects are mediated by diosgenin. Fenugreek containing diosgenin may be useful for ameliorating the glucose metabolic disorder associated with obesity.
Plasma phospholipids n‐3 polyunsaturated fatty acid is associated with metabolic syndrome
Authors: Huang Tao , Bhulaidok Subhachai , Cai Zhenzhen , Xu Tongcheng , Xu Fang , Wahlqvist Mark L. , Li Duo
Published: June 2010

The relationship between n‐3 PUFA and metabolic syndrome (MS) is not clear. The aim of this study was to examine relationships between plasma phospholipids (PL) n‐3 PUFA and MS in Chinese subjects. Nine hundred and twenty‐nine subjects were recruited in Hangzhou, China. Two hundred and ten (183 males, 27 females) with MS and 719 (545 males, 174 females) healthy subjects were identified in this cross‐sectional study. The prevalence of MS in females (24.56%) was significantly higher than that in males (10.04%) in this population. Total PUFA (p<0.001), n‐3 PUFA (p<0.001), and n‐3:n‐6 (p<0.001) were significantly lower in MS subjects compared to healthy subjects. Plasma phospholipid (PL), n‐3 PUFA was significantly inversely associated with MS (p=0.013). In addition, subjects with high levels of PL total fatty acids (FA) had a more than threefold higher likelihood of MS (OR=3.44, 95% CI=1.60–7.39) than the subjects with low levels of PL total FA. Our results suggest that plasma PL n‐3 PUFA was significantly inversely associated with MS, while high total FA were positively associated with MS in Chinese.
X‐ray magnetic circular dichroism and reflection anisotropy spectroscopy Kerr effect studies of capped magnetic nanowires
Authors: Cunniffe J. P. , McNally D. E. , Liberati M. , Arenholz E. , McGuinness C. , McGilp J. F.
Published: June 2010

Aligned Co wires grown on Pt(997) under ultra‐high vacuum conditions have been capped successfully by the epitaxial growth of Au monolayers (ML) at room temperature. The samples were kept under vacuum except when transferring between apparatus or when making some of the measurements. No degradation of the Co wires was detected during the measurements. The magneto‐optic response of the system was measured using X‐ray magnetic circular dichroism (XMCD) at the Co L2,3 edge and reflection anisotropy spectroscopy (RAS) at near normal incidence, which is sensitive to the normal component of the out‐of‐plane magnetization via the Kerr effect (MOKE). Capping the wires significantly impacts their magnetic properties. Comparison of the magneto‐optic response of the system at X‐ray and optical energies reveals small differences that are attributed to the induced moment in the Pt substrate and Au capping layer not picked up by the element specific XMCD measurements. The sensitivity of RAS‐MOKE is sufficient to allow the determination of the easy axis direction of the capped wires to within a few degrees. The results for a 6‐atom‐wide Co wire sample, capped with 6 ML of Au, are consistent with the capped wires possessing perpendicular magnetization.
Macroscopic movement of azo polymer chains by near‐field probes: Dependence on the illumination conditions
Authors: Savoini Matteo , Biagioni Paolo , Finazzi Marco , Duò Lamberto
Published: June 2010

The movement of photosensitive azo polymers induced by scanning near‐field illumination is studied. As a function of the photon flux illuminating the sample and exposure time, different effects are obtained: from a nanoscopic reorientation, inducing birefringence in the sample, to a macroscopic movement of the photosensitive polymers. It is also shown that this movement is strongly influenced by the state of incident light polarization. The combination of azo polymers and near‐field illumination allows encoding sub diffraction information and can be exploited in applications as nanomachining and nanofabrication.

magnified image

Birefringence signal associated to nanoscopic reorientation of the azomers.
Simulating the temperature dependence of surface state contributions to reflection anisotropy spectral features
Authors: Isted G. E. , Lane P. D. , Cole R. J.
Published: June 2010

By simulating the effect of temperature on the absorption spectra of Ag and Cu (110), we show the differing importance of the various processes influencing the temperature dependence of the width and intensity of the 1.7 eV Ag (110) reflection anisotropy spectroscopy (RAS) peak and the surface state contribution to the Cu (110) 2.1 eV RAS peak. Our results show that the significance of these processes in each case is governed by the energy gap between the associated occupied surface state involved and the Fermi energy.
Deep ultraviolet emission mechanisms in highly excited Al0.79Ga0.21N/AlN quantum wells
Authors: Oto Takao , Banal Ryan G. , Funato Mitsuru , Kawakami Yoichi
Published: June 2010

Excitation power dependence of photoluminescence (PL) properties was investigated on high‐quality Al0.79Ga0.21N/AlN multiple quantum wells (MQWs). The MQWs were grown by recently developed growth method, modified migration enhanced epitaxy based on metalorganic vapor phase epitaxy.

Clear transition of emission mechanisms from the exciton many body effect to electron‐hole plasma was observed as the excitation intensity was increased. The variation of PL peak energy was reasonably explained by bandgap renormalization, Burstein‐Moss shift, and screening of polarization‐induced electric fields. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
2DEG properties in InGaN/InN/InGaN‐based double channel HEMTs
Authors: Hasan Md. Tanvir , Kaysir Md. Rejvi , Islam Md. Sherajul , Bhuiyan Ashraful G. , Islam Md. Rafiqul , Hashimoto A. , Yamamoto A.
Published: June 2010

This paper describes the 2DEG properties of InGaN/InN/InGaN double channel high electron mobility transistor (DHEMT). These include an in‐depth theoretical investigation of 2DEG sheet carrier concentration and mobility. The 2DEG mobility is calculated using ensemble Monte Carlo taking into account all relevant scatterings. The calculated sheet carrier concentration reaches as high as 1.77×1014 cm‐2 for DHEMT. While for single channel high electron mobility transistor (SHEMT) the calculated sheet carrier concentration was found to be 7.06×1013 cm‐2. The maximum total 2DEG mobility is found to be around 12×104 and 8×104 cm2V‐1s‐1, respectively, for DHEMT and SHEMT for a sheet carrier concentration of ns = 5×1012 cm‐2 at 77 K. Thus, the 2DEG sheet carrier concentration and mobility for dual channel is higher than conventional single channel HEMTs. The high values of 2DEG sheet carrier concentration and mobility strongly suggest that the InGaN/InN/InGaN based double channel HEMT is very promising for the fabrication of high performance high speed device (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of InGaN/GaN and AlGaN/GaN superlattices by X‐ray diffraction and X‐ray reflectivity measurements
Authors: Sintonen S. , Suihkonen S. , Svensk O. , Törmä P. T. , Ali M. , Sopanen M. , Lipsanen H.
Published: June 2010

The commercial significance of superlattice structures is increasing due to greater demand of optoelectronic devices, such as the light emitting diode (LED). In order to optimize these devices, an accurate and reliable characterization method is needed. This paper describes in detail the characterization of superlattices with X‐ray scattering techniques. The thicknesses of the individual layers are determined by X‐ray reflectivity (XRR) measurements and the state of strain, the lattice constants and the compositions of ternary compounds by X‐ray diffraction (XRD) measurements.

The method is non‐destructive, and yields unique results, unlike characterizations based on simulation of symmetric XRD scans. These simulations were used for verification of results. The method was tested on InGaN and AlGaN superlattice structures. The measured and simulated parameter values agreed very well. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interplay of stimulated emission and Auger‐like effect in violet and blue InGaN laser diodes
Authors: Grzanka S. , Perlin P. , Czernecki R. , Marona L. , Boćkowski M. , Łucznik B. , Leszczyński M. , Khachapuridze A. , Goss J. , Schwarz U. T. , Suski T.
Published: June 2010

We have studied two types of InGaN laser diodes emitting at 410 and 440 nm, looking for the presence of the efficiency “droop” and its influence on the performance of these devices. By measuring the devices in two experimental geometries: a) along the resonator axis, b) perpendicularly to the cavity, we were able to conclude that the light emission process in these laser diodes operating below the threshold are governed by two mechanisms: Auger‐like effect and the stimulated recombination. The competition of these two mechanisms leads to the suppression of the droop if the light is observed along the axis of the cavity. The relatively low onset of the stimulated recombination may account for the robustness of these devices against the nonradiative process (Auger‐like recombination) appearing at high current densities. Additionally, we performed the characterization of InGaN light emitting diodes grown on substrates with varied In content and defect density. The results clearly demonstrate that the droop is not related in any way with the above mentioned parameters at least in the dislocation density range between 105 and 109 cm‐2 and In composition range between 0.1‐0.15. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN growth on LiNbO3 (0001) – a first‐principles simulation
Authors: Sanna Simone , Schmidt Wolf Gero
Published: June 2010

The growth of GaN on the LiNbO3 (0001) surface is simulated by means of first‐principles total‐energy calculations. Firstly the adsorption of single N and Ga monolayers is investigated and then the layer‐by‐layer growth of GaN on the polar substrate within different orientations is modeled. While adsorbing a N layer does not heavily affect the substrate morphology, the adsorption of a Ga layer causes a rearrangement of the atomic structure. Furthermore the N layer is more strongly bound to the substrate than the Ga layer. On the basis of our results, we propose a microscopic model for the GaN/LiNbO3 interface. The GaN and LiNbO3 (0001) planes are parallel, but rotated by 30° each other, with in‐plane epitaxial relationship [10$ \bar 1 $0]GaN II [11$ \bar 2 $0]. In this way the (0001) calculated in‐plane lattice mismatch between GaN and LiNbO3 is minimal and equal to 6.79% of the GaN lattice constant. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlGaN/GaN‐based normally‐off GaN MOSFET with stress controlled 2DEG source and drain
Authors: Im Ki‐Sik , Ha Jong‐Bong , Kim Ki‐Won , Lee Jong‐Sub , Kim Dong‐Seok , Choi Hyun‐Chul , Lee Jung‐Hee
Published: June 2010

AlGaN/GaN‐based normally‐off GaN MOSFET with stress controlled 2DEG source and drain was proposed and fabricated using Al2O3 gate oxide deposited on the fully recessed gate region. The proposed normally‐off Al2O3/GaN MOSFET utilized AlGaN/GaN heterostructure source and drain with extremely high 2DEG density of 1.87×1014 cm2 with mobility of 120 cm2V‐1s‐1 and the device results were compared to those obtained from the reference device with normal AlGaN/GaN heterostructure source and drain with 2DEG density of 1.33×1013 cm2 and mobility of 1070 cm2V‐1s‐1. The maximum drain current and maximum transconductance of the proposed device were 263 mA/mm and 72 mS/mm, respectively, about 7.3‐times and 5‐times larger than those of the reference device, which are comparable to or even higher than one of the best results obtained from various GaN MOSFETs reported by others. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical properties of (ZnO)x(ZnSe)ythin films for optoelectronic applications
Authors: Fridjine S. , Touihri S. , Boubaker K. , Amlouk M. , Belgacem S.
Published: June 2010

In this work, the spray pyrolysis system of aqueous solution contained zinc acetate as precursors is firstly selected to prepare ZnO thin films. Second, an annealing in selenium atmosphere using various time of these ZnO thin films has been used. The structural study shows that without selenium element (y = 0), ZnO thin films, were well crystallized in hexagonal structure and oriented preferentially along (002). To understand the optical behaviour as well as the structure in (ZnO)x(ZnSe)y alloys obtained from the mixture of these binaries materials, the optical analysis using the transmittance and reflectance R(%) and T(%) measurements of these alloys has been carried out. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heat treatment effects on the surface morphology and optical properties of ZnO nanostructures
Authors: Zainizan Sahdan M. , Hafiz Mamat M. , Salina M. , Khusaimi Zuraida , Noor Uzer M. , Rusop Mohamad
Published: June 2010

Zinc oxide (ZnO) nanostructures have received broad attention due to its wide applications especially for thin‐film solar cells and transistors. In this paper, we report the effects of heat treatment on the structural and optical properties of ZnO nanostructures. Zinc oxide nanostructures were synthesized using thermal chemical vapour deposition (CVD) method on glass substrate. The surface morphologies which were observed by scanning electron microscope (SEM) show that ZnO nanostructures change its shape and size when the annealing temperature increases from 400 °C to 600 °C. Structural measurement using X‐ray diffraction (XRD) has shown that ZnO nanostructures have the highest crystallinity and smallest crystallite size (20 nm) when annealed at 550 °C. Furthermore, the samples were optically characterized using Photoluminescence (PL) spectrometer. The PL spectra indicate that ZnO nanostructures have the highest peak at UV wavelength when annealed at 550 °C. The mechanism of the PL properties of ZnO nanostructures is also discussed. We conclude that ZnO nanostructures deposited using thermal CVD have the optimum structural and PL properties when annealed at 550 °C. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Titanium dioxide thin films deposited by the sol‐gel technique starting from titanium oxy‐acetyl acetonate: gas sensing and photocatalyst applications
Authors: Maldonado A. , Mayen‐Hernández S. A. , Tirado‐Guerra S. , de la L. Olvera M.
Published: June 2010

Titanium dioxide (TiO2) thin films were deposited onto sodocalcic glass plates by the sol‐gel technique, starting from a non‐alkoxide route, namely, titanium oxy‐acetyl acetonate as Ti precursor. Film thickness effect on both the gas sensing and photocatalytic degradation performance was studied. The as‐deposited films were annealed in air at 400 °C. All the X‐ray spectra of the films show a very broad‐peak centered in a 2θ angle around 30°. In the case of the thinnest films the surface morphology is uniform and very smooth, whereas for the thickest films the corresponding surface is covered by grains with a rod‐like shape with a length on the order of 140 nm. The films were tested both for two straightforward applications: ultraviolet assisted‐degradation of methylene blue dissolved in water, at different times, as well as gas sensor in a controlled propane (C3H8) atmosphere. As the film thickness increases, the degradation of methylene blue (MB) also increases. The thickest TiO2 thin films after being exposed by 5 hours to the catalytic degradation, promoted by ultraviolet illumination, showed a final MB solution degradation in the order of 48%. This reult can be associated with the increase in the effective exposed area of the TiO2 thin films. On the other hand, the exposition of the films to a controlled propane atmosphere produced a significant change in the surface electrical resistance of the films at operating temperatures of 200 °C and above. In fact, in the case of the thickest TiO2 films, a dramatic electrical resistance change of non‐exposed and propane exposed – 560 to 0.7 MΩ –, was registered. The results show that TiO2 films deposited by an economical deposition technique, as is the case of the sol‐gel technique, could have an important potential in industrial applications. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of free‐standing ultrathin films of porous metal‐organic frameworks by liquid‐phase epitaxy and subsequent delamination
Authors: Darbandi Masih , Arslan Hasan K. , Shekhah Osama , Bashir Asif , Birkner Alexander , Wöll Christof
Published: June 2010

In this work we describe an approach to fabricate MOF (metal‐organic framework) platelets with predefined shapes and well‐defined thicknesses. The process is based on growing thin, highly oriented and ordered MOF films by selective liquid‐phase epitaxy on prestructured organic substrates. In a second step, the MOF platelets are delaminated employing a lift‐off process. The freestanding MOF platelets were characterized with TEM and SEM, which showed no evidence of fracture or deformation of the delaminated shapes. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic quantum motions in hydrogen molecule ion
Authors: Yang Ciann‐Dong , Weng Hung‐Jen
Published: June 2010

The hydrogen molecule ion is a two‐center force system expressed under the prolate spheroidal coordinates, whose quantum motions and quantum trajectories have never been addressed in the literature before. The momentum operators in this coordinate system are derived for the first time from the Hamilton equations of motion and used to construct the Hamiltonian operator. The resulting Hamiltonian comprises a kinetic energy T and a total potential VTotal consisting of the Coulomb potential and a quantum potential. It is shown that the participation of the quantum potential and the accompanied quantum forces in the force interaction within H2+ is essential to develop an electronic motion consistent with the prediction of the probability density function |Ψ|2. The motion of the electron in H2+ can be either described by the Hamilton equations derived from the Hamiltonian H = TK + VTotal or by the Lagrange equations derived from the Lagrangian H = TK − VTotal. Solving the equations of motion with different initial positions, we show that the solutions yield an assembly of electronic quantum trajectories whose distribution and concentration reconstruct the σ and π molecular orbitals in H2+. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Conformational study of two diasteroisomers of vinylcatechin dimers in a methanol solution
Authors: Brás Natércia F. , Cruz Luís , Fernandes Pedro A. , De Freitas Victor , Ramos Maria João
Published: June 2010

Red wine possess anthocyanins (red colored pigments) and flavan‐3‐ol compounds (associated to the flavor). In an acidic environment, these compounds have higher reactivity due to the acidic character of the phenolic groups. Vinylcatechin adducts play a crucial role as intermediates in the formation mechanism of some anthocyanin‐derived pigments (e.g., pyranoanthocyanins) during wine aging. They have gained increasing attention because of the large number of compounds detected in wines and their unusual spectroscopic properties. However, vinylcatechins are very unstable molecules in acidic solutions and their occurrence in wines has never been detected, probably due to their high reactivity. Using computational methods, we have characterized and identified the different conformations of two stable diasteroisomers (9S,11R)‐ and (9R,11S)‐vinylcatechin dimers, which were obtained in model wine solutions from acid‐catalyzed dimerization of vinylcatechin. To identify the different conformations for both isomers, first potential energy surface calculation around the most relevant dihedral angles of each isomer were performed using the density functional theory (DFT) approach with the B3LYP hybrid density functional. Molecular Dynamics (MD) simulations starting from the previous minima were subsequently performed to investigate the possible conformations acquired by the two different compounds in a methanol solution. Six and five different conformations were obtained during the MD simulations for (9S,11R) and (9R,11S) isomers, respectively. Ten nanoseconds of MD simulations were enough to obtain the most favored conformations of these molecules. DFT calculations were used for the optimizations of all structures in vacuum as well as in a methanol environment. Gibbs free energy values were calculated for all structures, and these values show that similar quantities of both (9S,11R) and (9R,11S) diasteroisomers are obtained in a methanol solution, and that their formation is thermodynamically favored. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
CHARMM force field parameterization of rosiglitazone
Authors: Hansson Anders , Souza Paulo C. T. , Silveira Rodrigo L. , Martínez Leandro , Skaf Munir S.
Published: June 2010

We develop a CHARMM‐based interaction potential for rosiglitazone, a well‐known selective ligand to the γ isoform of the peroxisome proliferator‐activated receptor (PPARγ) and widely marketed antidiabetic drug of the thiazolidinedione (TZD) class. We derive partial atomic charges and dihedral torsion potentials for seven rotations in the molecule, for which there are no analogs available in CHARMM. The potential model is validated by performing a series of molecular dynamics simulations of rosiglitazone in neat water and of a fully solvated rosiglitazone‐PPARγ complex. The structural and dynamical behavior of the complex is analyzed in comparison with available experimental data. The potential parameters derived here are readily transferable to a variety of pharmaceutically important TZD compounds. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010