bluuebunny/crossref_metadata_2025 huggingface dataset:
Apo‐parvalbumin as an intrinsically disordered protein
Authors: Permyakov Sergei E. , Bakunts Anush G. , Denesyuk Alexander I. , Knyazeva Ekaterina L. , Uversky Vladimir N. , Permyakov Eugene A.
Published: February 2008

Recently defined family of intrinsically disordered proteins (IDP) includes proteins lacking rigid tertiary structure meanwhile fulfilling essential biological functions. Here we show that apo‐state of pike parvalbumin (α‐ and β‐isoforms, pI 5.0 and 4.2, respectively) belongs to the family of IDP, which is in accord with theoretical predictions. Parvalbumin (PA) is a 12‐kDa calcium‐binding protein involved into regulation of relaxation of fast muscles. Differential scanning calorimetry measurements of metal‐depleted form of PA revealed the absence of any thermally induced transitions with measurable denaturation enthalpy along with elevated specific heat capacity, implying the lack of rigid tertiary structure and exposure of hydrophobic protein groups to the solvent. Calcium removal from the PAs causes more than 10‐fold increase in fluorescence intensity of hydrophobic probe bis‐ANS and is accompanied by a decrease in α‐helical content and a marked increase in mobility of aromatic residues environment, as judged by circular dichroism spectroscopy (CD). Guanidinium chloride‐induced unfolding of the apo‐parvalbumins monitored by CD showed the lack of fixed tertiary structure. Theoretical estimation of energetics of the charge–charge interactions in the PAs indicated their pronounced destabilization upon calcium removal, which is in line with sequence‐based predictions of disordered protein chain regions. Far‐UV CD studies of apo‐α‐PA revealed hallmarks of cold denaturation of the protein at temperatures below 20°C. Moreover, a cooperative thermal denaturation transition with mid‐temperature at 10–15°C is revealed by near‐UV CD for both PAs. The absence of detectable enthalpy change in this temperature region suggests continuous nature of the transition. Overall, the theoretical and experimental data obtained show that PA in apo‐state is essentially disordered nevertheless demonstrates complex denaturation behavior. The native rigid tertiary structure of PA is attained upon association of one (α‐PA) or two (β‐PA) calcium ions per protein molecule, as follows from calorimetric and calcium titration data. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Early timing and new combinations to increase the efficacy of neonicotinoid–entomopathogenic nematode (Rhabditida: Heterorhabditidae) combinations against white grubs (Coleoptera: Scarabaeidae)
Authors: Koppenhöfer Albrecht M , Fuzy Eugene M
Published: February 2008

BACKGROUND: An investigation was carried out to determine whether new neonicotinoid–nematode combinations and earlier applications against younger larval stages could increase the efficacy of synergistic neonicotinoid–entomopathogenic nematode combinations against white grubs.

RESULTS: In the laboratory, combinations of the neonicotinoids imidacloprid and clothianidin and the nematodes Heterorhabditis bacteriophora Poinar and H. zealandica Poinar against third instars were compared. In Anomala orientalis (Waterhouse) and Popillia japonica Newman, H. bacteriophora–imidacloprid combinations showed the most consistent synergism but did not cause significantly higher mortality than H. zealandica–imidacloprid combinations. In Cyclocephala borealis Arrow, there was no clear trend as to which combinations caused the most consistent synergism, but H. zealandica–imidacloprid combinations tended to cause the highest mortalities. In the laboratory, imidacloprid–H. bacteriophora combinations provided more consistent synergism against third‐instar than against second‐instar A. orientalis, but mortality was higher in second instars. In field experiments, imidacloprid–H. bacteriophora combinations against A. orientalis and P. japonica provided more consistent synergism when applied in mid‐September but more consistent control when applied in late August.

CONCLUSIONS: Imidacloprid is a better synergist for entomopathogenic nematodes than clothianidin. Imidacloprid–nematode combinations are more effective against second instars than against third instars, allowing rate reductions of both agents to make this approach more competitive with full‐rate applications of neonicotinoid alone. Copyright © 2008 Society of Chemical Industry
Effect of indium‐doped interlayer on the strain relief in GaN films grown on Si(111)
Authors: Wu Jiejun , Zhao Lubing , Zhang Guoyi , Liu Xianglin , Zhu Qinsheng , Wang Zhanguo , Jia Quanjie , Guo Liping , Hu Tiandou
Published: February 2008

Crack‐free GaN films have been achieved by inserting an In‐doped low‐temperature (LT) AlGaN interlayer grown on silicon by metalorganic chemical vapor deposition. The relationship between lattice constants c and a obtained by X‐ray diffraction analysis shows that indium doping interlayer can reduce the stress in GaN layers. The stress in GaN decreases with increasing trimethylindium (TMIn) during interlayer growth. Moreover, for a smaller TMIn flow, the stress in GaN decreases dramatically when In acts as a surfactant to improve the crystallinity of the AlGaN interlayer, and for a larger TMIn flow, the stress will increase again. The decreased stress leads to smoother surfaces and fewer cracks for GaN layers by using an In‐doped interlayer than by using an undoped interlayer. In doping has been found to enhance the lateral growth and reduce the growth rate of the c face. It can explain the strain relief and cracks reduction in GaN films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement of nonlinear optical properties of Au–TiO2 granular composite with high percolation threshold
Authors: Zhou Z. K. , Li M. , Su X. R. , Zhai Y. Y. , Song H. , Han J. B. , Hao Z. H.
Published: February 2008

Two series of Au–TiO2 composite films with Au percola‐ tion threshold qC of 0.34 and 0.82 were prepared by using sputtering technique at the pressure of 5.0 × 10–2 and 8.0 × 10–2 Torr, respectively. As qC increases from 0.34 to 0.82, the plasmon resonant absorption of the composite films near qC shifts from about 700 nm to 760 nm, and the maximal second harmonic generation (SHG) intensity increases by 20%, the maximal nonlinear absorption coefficient increases from –3.0 × 104 cm/GW to 1.7 × 105 cm/GW, and the maximal nonlinear refraction index increases from a very small value to –2.6 cm2/GW. The large second‐ and third‐order optical nonlinearity of the Au–TiO2 composite films with high qC is attributed to the high density of Au particle in the nonconductive film and the strong local field enhancement caused by the surface plasmon resonant absorption. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of thermal annealing treatment in oxygen atmosphere on grain boundary chemistry and non‐ohmic properties of SnO2·MnO polycrystalline semiconductors
Authors: Orlandi M. O. , Bueno P. R. , Longo E.
Published: February 2008

The present work studied the influence of thermal treatment in oxygen rich atmosphere on heterogeneous junctions in Mn‐doped SnO2 polycrystalline system presenting varistor behavior. The samples were prepared by conventional oxide mixture methodology, and were submitted to heat treatment in oxygen rich atmosphere at 900 °C for 2 h. The samples were characterized by X‐ray diffraction, scanning electron microscopy, dc and ac electrical measurements. The results showed that there is an evident relationship between the microstructure heterogeneity and non‐ohmic electrical properties. It was found that for this SnO2·MnO‐based varistor system the heat treatment in oxygen rich atmosphere does not necessarily increase the varistors' properties, which was related to the decrease in the grain boundary resistance. The results are compared with Co‐doped SnO2 varistors and ZnO based varistors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear electrical characteristics of semi‐insulating GaAs
Authors: Kurt H. Y. , Sadiq Y. , Salamov B. G.
Published: February 2008

Nonlinear electrical transport processes in a semiconductor‐gas discharge structure with semi‐insulating GaAs are studied for a wide range of gas pressures, interelectrode distances and different diameters of the photocathode areas. A primary destabilization of homogeneous state observed in a planar dc‐driven structure is due to nonlinear transport properties of GaAs photocathode. GaAs samples present N‐shaped negative differential conductivity under high‐electric fields and the presence of the deep electronic levels of defects, the so‐called EL2 centers, gives rise to the N‐type‐NDC of the material, as a consequence, to low‐frequency oscillations in current when a dc voltage of a high enough magnitude is applied to a GaAs photocathode. It is important to note that we have experimentally investigated the above‐mentioned nonlinear electrical characteristics of GaAs by a new‐suggested method and our experimental findings are obviously in good agreement with estimated results reported by other independent authors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High resolution measurement of the thermal expansion coefficient of semiconductor multilayer lateral nanostructures
Authors: Brüser B. , Panzner T. , Grigorian S. , Grenzer J. , Zorn M. , Zeimer U. , Pietsch U.
Published: February 2008

We measured the thermal expansion coefficient (TEC) of a vertically stacked multi‐quantum‐well (MQW) structure buried under a thick GaAs top layer before and after lateral patterning of the GaAs top layer. After patterning the TEC of the whole MQW structure differs from that of the planar structure by about 20%. Based on calculations in terms of methods of finite elements the effect is explained by the influence of the strain field originating from the bottom edges of the etched nanostructure. Due to the long range nature of this strain field the strain release within the individual quantum wells changes as a function from the distance from the valley. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Liquids at positive and negative pressure
Authors: Heyes D. M.
Published: February 2008

A Molecular Dynamics simulation study has been carried out of the Lennard–Jones fluid in the stable liquid and metastable liquid–vapour co‐existence regions. The interest has been mainly in states for which the pressure of the fluid is negative, and how they compare with those at positive pressure. The behaviour of the LJ fluid shows parallels with that of water, with the maximum tensile strength near the triple point being approximately seven times the critical pressure. The maximum tensile strength increases with cooling. Many of the properties, such as elastic moduli, show a smooth transition across the liquid–vapour boundary, on the liquid side, and a monotonic variation in the metastable region of the phase diagram. There is however a similarity in behaviour of combinations of the mechanical properties and the equation of state; for example, the pressure and infinite frequency Poissons ratio have minima at approximately the same densities. Insights into the heterogeneity of the assembly of particles are provided by probability distributions of the net force on a molecule and that of a definition for the local pressure experienced by a molecule, or ‘pressurelet'. The maximum negative pressure coincides with the maximum fraction of molecules individually experiencing a negative pressure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Absolute measurements and certified reference material for iron isotopes using multiple‐collector inductively coupled mass spectrometry
Authors: Zhou Tao , Zhao Motian , Wang Jun , Lu Hai
Published: February 2008

Two enriched isotopes, 99.94 at.% 56Fe and 99.90 at.% 54Fe, were blended under gravimetric control to prepare ten synthetic isotope samples whose 56Fe isotope abundances ranged from 95% to 20%. For multiple‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) measurements typical polyatomic interferences were removed by using Ar and H2 as collision gas and operating the MC‐ICP‐MS system in soft mode. Thus high‐precision measurements of the Fe isotope abundance ratios were accomplished. Based on the measurement of the synthetic isotope abundance ratios by MC‐ICP‐MS, the correction factor for mass discrimination was calculated and the results were in agreement with results from IRMM014. The precision of all ten correction factors was 0.044%, indicating a good linearity of the MC‐ICP‐MS method for different isotope abundance ratio values. An isotopic reference material was certified under the same conditions as the instrument was calibrated. The uncertainties of ten correction factors K were calculated and the final extended uncertainties of the isotopic certified Fe reference material were 5.8363(37) at.% 54Fe, 91.7621(51) at.% 56Fe, 2.1219(23) at.% 57Fe, and 0.2797(32) at.% 58Fe. Copyright © 2008 John Wiley & Sons, Ltd.
Cross‐layer bandwidth and power allocation for a two‐hop link in wireless mesh network
Authors: Cheng Peng , Zhang Zhaoyang , Yu Guanding , Chen Hsiao‐Hwa , Qiu Peiliang
Published: February 2008

In this paper, a cross‐layer analytical framework is proposed to analyze the throughput and packet delay of a two‐hop wireless link in wireless mesh network (WMN). It considers the adaptive modulation and coding (AMC) process in physical layer and the traffic queuing process in upper layers, taking into account the traffic distribution changes at the output node of each link due to the AMC process therein. Firstly, we model the wireless fading channel and the corresponding AMC process as a finite state Markov chain (FSMC) serving system. Then, a method is proposed to calculate the steady‐state output traffic of each node. Based on this, we derive a modified queuing FSMC model for the relay to gateway link, which consists of a relayed non‐Poisson traffic and an originated Poisson traffic, thus to evaluate the throughput at the mesh gateway. This analytical framework is verified by numerical simulations, and is easy to extend to multi‐hop links. Furthermore, based on the above proposed cross‐layer framework, we consider the problem of optimal power and bandwidth allocation for QoS‐guaranteed services in a two‐hop wireless link, where the total power and bandwidth resources are both sum‐constrained. Secondly, the practical optimal power allocation algorithm and optimal bandwidth allocation algorithm are presented separately. Then, the problem of joint power and bandwidth allocation is analyzed and an iterative algorithm is proposed to solve the problem in a simple way. Finally, numerical simulations are given to evaluate their performances. Copyright © 2008 John Wiley & Sons, Ltd.
X‐ray fluorescence—analysis of 19th century stamps
Authors: Cesareo Roberto , Brunetti Antonio
Published: February 2008

Latin‐American stamps of the period 1850–1900 were analyzed and scanned with a portable x‐ray fluorescence equipment composed of a small size x‐ray tube and a Si‐PIN detector with a capillary collimator, with the aim of identifying their characteristic pigments, establishing in which period of time pigments containing inorganic components have been employed and their evolution vs time. Copyright © 2008 John Wiley & Sons, Ltd.
On the streamline topology of inviscid flow with multiple points in a homogenous stream
Authors: Kolonits F.
Published: February 2008

Special streamlines in the flow with circulation around a cylinder cross themselves, maybe even three times. The simple crossing happens orthogonally, while the threefold one shows up π/3 angles among the branches. There are no discontinuous changes as the pattern develops with growing circulation. These observations yield a general statement. Here we show that if a z = F(x, y) is a solution of the Δ z = 0 Laplace equation and a z = const curve intersects itself (once or several times), then the branches running to that crossing point shall form equal angles.
Antiplane shear deformations of an anisotropic elliptical inhomogeneity with imperfect or viscous interface
Authors: Wang X. , Pan E.
Published: February 2008

Based on the Lekhnitskii‐Eshelby approach of two‐dimensional anisotropic elasticity, a semi‐analytical solution is derived for the problem associated with an anisotropic elliptical inhomogeneity embedded in an infinite anisotropic matrix subjected to remote uniform antiplane shear stresses. In this research, the linear spring type imperfect bonding conditions are imposed on the inhomogeneity‐matrix interface. We use a different approach than that developed by Shen et al. (2000) to expand the function encountered during the analysis for an imperfectly bonded interface. Our expansion method is in principle based on Isaac Newton's generalized binomial theorem. The solution is verified, both theoretically and numerically, by comparison with existing solution for a perfect interface. It is observed that the stress field inside an anisotropic elliptical inhomogeneity with a homogeneously imperfect interface is intrinsically nonuniform. The explicit expression of the nonuniform stress field within the inhomogeneity is presented. The nonuniform stress field inside the inhomogeneity is also graphically illustrated. A difference in internal stress distribution between a composite composed of anisotropic constituents and a composite composed of isotropic constituents is also observed. We finally extend the solution derived for a linear spring type imperfect interface to address an elliptical inhomogeneity with a viscous interface described by the linear law of rheology. It is observed that the stress field inside an elliptical inhomogeneity with a viscous interface is nonuniform and time‐dependent.
Delayed Celiotomy or Laparoscopy as part of the Nonoperative Management of Blunt Hepatic Trauma
Authors: Letoublon Christian , Chen Yao , Arvieux Catherine , Voirin David , Morra Irene , Broux Christophe , Risse Olivier
Published: February 2008

Background

Nonoperative management (NOM) is considered standard treatment for 80% of blunt hepatic trauma (BHT). NOM is associated with some events that may require delayed operation (DO), usually considered a criterion of failure of NOM.

Methods

A retrospective case note review was performed on 257 consecutive patients with BHT, with a median age of 32.7 years, admitted from 1994 to 2005. We considered the 186 patients (72%) who had an initial indication of NOM, and focused on the 28 patients who were secondarily operated (DO), mainly on the 22 patients operated on for liver‐related indications. Celioscopy was used in five cases.

Results

The severity grade of these 22 patients was: zero grade I, seven grade II, ten grade III, four grade IV, one grade V. The timing of DO varied from day 0 to day 11. Ten patients were operated on for a peritoneal inflammatory syndrome. Death occurred in three patients at days 2, 10, and 125. One was attributed to underestimation of hepatic necrosis, another to a nondiagnosed peritoneal inflammatory syndrome; 27, 3% of the patients had liver‐related complications.

Conclusions

Our data suggest that BHT treated by NOM must be frequently reevaluated and that DO is an actual part of the so‐called nonoperative treatment. The use of laparoscopic washing has to be proposed as soon as day 3 or 5 in patients with large hemoperitoneum and any sign of inflammatory response (fever, leukocytosis, discomfort, tachycardia).
Optimization of Cottonseed Oil Ethanolysis to Produce Biodiesel High in Gossypol Content
Authors: Joshi Hem Chandra , Toler Joe , Walker Terry
Published: February 2008

Transesterification of cottonseed oil was carried out using ethanol and potassium hydroxide (KOH). A central composite design with six center and six axial points was used to study the effect of catalyst concentration, molar ratio of ethanol to cottonseed oil and reaction temperature for percentage yield (% yield) and percentage initial absorbance (%A385nm) of the biodiesel. Catalyst concentration and molar ratio of ethanol to cottonseed oil were the most significant variables affecting percentage conversion and %A385nm. Maximum predicted % yield of 98% was obtained at a catalyst concentration of 1.07% (wt/wt) and ethanol to cottonseed oil molar ratio of 20:1 at reaction temperature of 25 °C. Maximum predicted %A385nm of more than 80% was obtained at 0.5% (wt/wt) catalyst concentration and molar ratio of 3:1 at 25 °C. The response surfaces that described % yield and %A385nm were inversely related. Gossypol concentration (% wt), oxidative stability and %A385nm of biodiesel were found to be highly correlated with each other. Hence, color %A385nm is a measure of the amount of pigments present in biodiesel fuels that have not yet been subjected to autoxidation. High gossypol concentration also corresponds to a fuel with high oxidative stability. The fatty acid ethyl esters (FAEE) produced from cottonseed oil had superior oxidative stability to fatty acid methyl esters (FAME) produced from cottonseed oil.
Activation of NO donors in mitochondria: Peroxidase metabolism of (2‐hydroxyamino‐vinyl)‐triphenyl‐phosphonium by cytochrome c releases NO and protects cells against apoptosis
Authors: Stoyanovsky Detcho A. , Vlasova Irina I. , Belikova Natalia A. , Kapralov Alexandr , Tyurin Vladimir , Kagan Valerian E.
Published: February 2008

In mitochondrial apoptosis, the formation of cytochrome c–cardiolipin complex ([CL‐cyt c]) with peroxidase properties is an early event in the cascade of reactions that leads to cell death. Herein, we report the synthesis of a new prodrug, (2‐hydroxyamino‐vinyl)‐triphenyl‐phosphonium (HVTP), which compartmentalizes exclusively into mitochondria, undergoes a [CL‐cyt c]‐catalyzed bioactivation to nitric oxide (NO), inhibits peroxidase activity, and protects cells from apoptosis.
Mimicking phosphorylation of Ser‐74 on human deoxycytidine kinase selectively increases catalytic activity for dC and dC analogues
Authors: McSorley Theresa , Ort Stephan , Hazra Saugata , Lavie Arnon , Konrad Manfred
Published: February 2008

Intracellular phosphorylation of dCK on Ser‐74 results in increased nucleoside kinase activity. We mimicked this phosphorylation by a Ser‐74‐Glu mutation in bacterially produced dCK and investigated kinetic parameters using various nucleoside substrates. The S74E mutation increases the k
cat values 11‐fold for dC, and 3‐fold for the anti‐cancer analogues dFdC and AraC. In contrast, the rate is decreased for the purine substrates. In HEK293 cells, we found that by comparing transiently transfected dCK(S74E)‐GFP and wild‐type dCK‐GFP, mimicking the phosphorylation of Ser‐74 has no effect on cellular localisation. We note that phosphorylation may represent a mechanism to enhance the catalytic activity of the relatively slow dCK enzyme.
BM88/Cend1 is involved in histone deacetylase inhibition‐mediated growth arrest and differentiation of neuroblastoma cells
Authors: Politis Panagiotis K. , Akrivou Sofia , Hurel Catherine , Papadodima Olga , Matsas Rebecca
Published: February 2008

Histone deacetylase inhibitors arrest the growth of neuroblastoma cells and induce differentiation. Identification of target genes that co‐ordinate and mediate these effects is important for understanding the function of this novel class of antitumour drugs. We report here that trichostatin‐A (TSA) specifically induces the transcription of Cend1, a neuronal‐lineage specific regulator of cell cycle exit and differentiation, in neuroblastoma Neuro2A cells, but not in non‐neuronal cells. Furthermore, we show that knockdown of Cend1 alleviates both the anti‐proliferative and differentiation effect of TSA. Our findings suggest that Cend1 is an important molecular target for HDAC inhibition.
TAT‐Hsp40 inhibits oxidative stress‐mediated cytotoxicity via the inhibition of Hsp70 ubiquitination
Authors: Kim Soo-A , Chang Sunghoe , Yoon Jung-Hoon , Ahn Sang-Gun
Published: February 2008

Heat shock protein 40 (Hsp40) functions as a co‐chaperone of mammalian Heat shock protein 70 (Hsp70) and facilitates the ATPase activity of Hsp70, and also promotes the cellular protein folding and renaturation of misfolded proteins. In an effort to assess the effects of Hsp40, we generated TAT‐fused Hsp40 (TAT‐Hsp40). The cells were transduced with TAT‐Hsp40 and exposed to H2O2. We demonstrated that the TAT‐Hsp40‐transduced cells were more resistant to cellular cytotoxicity and cell death. In particular, the degradation of Hsp70 was significantly reduced in TAT‐Hsp40‐containing cells as a consequence of reduced ubiquitin–proteasome activity after oxidative injury. These data support the notion that Hsp40 may confer resistance to oxidative stress via the prevention of proteasome activity.
Switch between tyrosinase and catecholoxidase activity of scorpion hemocyanin by allosteric effectors
Authors: Nillius Dorothea , Jaenicke Elmar , Decker Heinz
Published: February 2008

Phenoloxidases and hemocyanins have similar type 3 copper centers although they perform different functions. Hemocyanins are oxygen carriers, while phenoloxidases (tyrosinase/catecholoxidase) catalyze the initial step in melanin synthesis. Tyrosinases catalyze two subsequent reactions, whereas catecholoxidases catalyze only the second one. Recent results indicate that hemocyanins can also function as phenoloxidases and here we show for the first time that hemocyanin can be converted to phenoloxidase. Furthermore, its substrate specificity can be switched between catecholoxidase and tyrosinase activity depending on effectors such as hydroxymethyl‐aminomethan (Tris) and Mg2+‐ions. This demonstrates that substrate specificity is not caused by a chemical modification of the active site.
Impact of education on food behaviour, body composition and physical fitness in children
Authors: Parizkova Jana
Published: February 2008

The increasing prevalence of obesity during growth and development is significantly related to the education of children, and also to that of parents who influence food intake and physical activity from the beginning of life. The effect of maternal level of education has been shown in regular anthropometric surveys in 10-year intervals since 1951. This concerns the mother's own nutrition and physical activity regimen as well as the child's nutrition since birth, including the duration of breast-feeding. Children of parents with overweight and obesity were shown more often to be obese, as was the case for children from families with the lowest level of education, or from smaller communities where the level of education is usually lower than in larger cities. The composition of the mother's diet during pregnancy had, for example, an effect on the blood lipids of newborns. During preschool age, less body fat, a higher level of HDL, and higher levels of cardiorespiratory fitness, skill and physical performance were found in active children. In school-age children, when obesity increases, a number of prevention programmes using diet, exercise and behavioural intervention have been developed for schools, communities, churches, and/or have been organized by special institutions and medical centres, which were most efficient in family groups. The greatest reduction of weight, BMI and fatness, and improvement of functional capacity, and hormonal and metabolic parameters were achieved in summer camps or spas, with consistent and monitored nutrition, exercise and behavioural treatment. Fluctuation of positive outcomes occurred due to the interruption of the educational process during the school year, and repeated long-lasting interventions have been always necessary for permanent desirable results.
Differences in oviposition behaviour of two sympatric sibling species of the genus Ostrinia
Authors: Malausa T. , Pélissié B. , Piveteau V. , Pélissier C. , Bourguet D. , Ponsard S.
Published: February 2008

Changes in host preferences are thought to be a major source of genetic divergence between phytophagous insect taxa. In western Europe, two sympatric taxa, O. nubilalis (the European corn borer) and O. scapulalis, feed mainly on maize and hop or mugwort, respectively. These two species may have diverged without geographic isolation after a host shift of ancestral populations onto maize or another cultivated species (e.g. sorghum). A previous study using inbred laboratory strains revealed that the two species differ in their oviposition choices in maize-mugwort tests. We sampled four natural populations in France (two of each taxon) and tested their oviposition behaviour toward four of their main host plant species: maize, sorghum, mugwort and hop. O. nubilalis females showed a very high preference for laying their eggmasses on maize, whereas O. scapulalis females displayed a more balanced range of preferences. O. nubilalis females were attracted slightly to sorghum, suggesting that this plant is an accidental, rather than a regular and ancestral host plant of O. nubilalis. One important result arising from this study is the significant proportion of eggs laid by both Ostrinia species on hop. This may explain why some stands of hop are sometimes not only infested by O. scapulalis but also by O. nubilalis larvae, a situation preventing assortative mating based on microallopatry. Hence, further studies must be conducted to see whether the host preference in the genus Ostrinia might be linked to assortative mating by a mechanism that is not mediated by the host plant.
Discrete subgroups of PU(2, 1) with screw parabolic elements
Authors: KAMIYA SHIGEYASU , PARKER JOHN R.
Published: February 2008

We give a version of Shimizu's lemma for groups of complex hyperbolic isometries one of whose generators is a parabolic screw motion. Suppose thatGis a discrete group containing a parabolic screw motionAand letBbe any element ofGnot fixing the fixed point ofA. Our result gives a bound on the radius of the isometric spheres ofBandB−1in terms of the translation lengths ofAat their centres. We use this result to give a sub-horospherical region precisely invariant under the stabiliser of the fixed point ofAinG.
GPS‐based atmospheric precipitable water vapor estimation using meteorological parameters interpolated from NCEP global reanalysis data
Authors: Jade Sridevi , Vijayan M. S. M.
Published: February 2008

This study for the first time used the Indian GPS network data along with the interpolated National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis meteorological data to estimate the precipitable water vapor (PWV) over the Indian atmosphere for a 4 year period (2001–2004) at 21 Indian GPS and 7 International GNSS Service stations. The site‐specific daily average meteorological data required for water vapor estimation at these sites is obtained by performing vertical interpolation on 2.5 × 2.5° gridded NCEP/NCAR global reanalysis data set available at 17 pressure levels and horizontal interpolation on similarly gridded NCEP/NCAR data set available at the surface. The comparison of the site‐specific interpolated surface pressure and temperature thus obtained from NCEP/NCAR data with the measured pressure and temperature profiles available at six GPS sites gives biases of <1 mbar and <3°C which exhibits the robustness of the interpolation schemes. The water vapor estimated at these six sites located in different geographical regions using interpolated surface pressure and weighted mean temperature values from NCEP data compare well (bias < 0.5 mm and standard deviation < 0.6 mm) with water vapor estimated using measured surface pressure and temperature values. GPS PWV estimates also compare well (bias < 3 mm) with the PWV estimates from the nearby radiosonde sites. GPS PWV values at all the sites compare well (bias < 5 mm) with the horizontally interpolated NCEP PWV values except for few sites located in the highly undulated terrain. These GPS PWV values of the Indian network (4–35°N) are then used to model the spatial variability of PWV over the Indian subcontinent as a function of zenith wet delay (ZWD). The modeled spatial variability function gives a quick and reliable estimate of near real‐time GPS PWV in Indian subcontinent directly from ZWD thus eliminating the need of site‐specific weighted mean temperature values.
Enzymes of adenosine metabolism in the brain: diurnal rhythm and the effect of sleep deprivation
Authors: Mackiewicz Miroslaw , Nikonova Elena V. , Zimmerman John E. , Galante Raymond J. , Zhang Lin , Cater Jacqueline R. , Geiger Jonathan D. , Pack Allan I.
Published: February 2008

Adenosine plays a role in promoting sleep, an effect that is thought to be mediated in the basal forebrain. Adenosine levels vary in this region with prolonged wakefulness in a unique way. The basis for this is unknown. We examined, in rats, the activity of the major metabolic enzymes for adenosine – adenosine deaminase, adenosine kinase, ecto‐ and cytosolic 5′‐nucleotidase – in sleep/wake regulatory regions as well as cerebral cortex, and how the activity varies across the day and with sleep deprivation. There were robust spatial differences for the activity of adenosine deaminase, adenosine kinase, and cytosolic and ecto‐5′‐nucleotidase. However, the basal forebrain was not different from other sleep/wake regulatory regions apart from the tuberomammillary nucleus. All adenosine metabolic enzymes exhibited diurnal variations in their activity, albeit not in all brain regions. Activity of adenosine deaminase increased during the active period in the ventrolateral pre‐optic area but decreased significantly in the basal forebrain. Enzymatic activity of adenosine kinase and cytosolic‐5′‐nucleotidase was higher during the active period in all brain regions tested. However, the activity of ecto‐5′‐nucleotidase was augmented during the active period only in the cerebral cortex. This diurnal variation may play a role in the regulation of adenosine in relationship to sleep and wakefulness across the day. In contrast, we found no changes specifically with sleep deprivation in the activity of any enzyme in any brain region. Thus, changes in adenosine with sleep deprivation are not a consequence of alterations in adenosine enzyme activity.
Zinc toxicity on neonatal cortical neurons: involvement of glutathione chelation
Authors: Chen Chun‐Jung , Liao Su‐Lan
Published: February 2008

Several mechanisms have been implicated in pathological neuronal death including zinc neurotoxicity, calcium excitotoxicity and oxidative injury. Glutathione (GSH) serves to provide reducing equivalents for the maintenance of oxidant homeostasis, and also plays roles in intracellular and intercellular signaling in the brain. We investigated the role of GSH homeostasis in the neurotoxic action of zinc using both mixed cortical cultures containing neurons and glia, and cortical neurons prepared from 1‐day‐old rats. Zinc caused neuronal cell death in a concentration‐dependent manner. In parallel, a high concentration of zinc depleted GSH, in a time‐dependent manner, preceding the onset of neuronal damage. Depletion of GSH by diethylmaleate injured neurons and exacerbated zinc‐induced death. In contrast, replenishment of GSH attenuated zinc neurotoxicity. The thiol‐containing compounds N‐acetylcysteine and GSH chemically chelated zinc leading to decreases in the influx of zinc, the fall in GSH level and neuronal death. Interestingly, the glycolytic substrate pyruvate, but not lactate, chelated zinc concentration dependently and prevented its toxicity. On the other hand, pyrrolidine dithiocarbamate, serving as a zinc chaperon, enhanced its entry and toxicity. The results suggest that zinc non‐enzymatically depleted GSH, an intrinsic factor for neuron survival, leading to activation of the cellular death signal and eventually neuronal death.
Experimental evidences for emittance degradation by space charge effect when using a focusing solenoid below an electron cyclotron resonance ion source
Authors: Machicoane G. , Doleans M. , Stetson J. , Wu X. , Závodszky P. A.
Published: February 2008

Solenoids are widely used to provide initial focusing of beams extracted from an ion source. However, in the case of an electron cyclotron resonance (ECR) ion source, the extracted beam will usually include different ion species and for each of them a wide distribution of charge states. When such a multicomponent beam is focused by a solenoid, the ions with a Q∕A larger than the beam of interest are overfocused and usually go through a waist before reaching the analyzing magnet. If the beam currents obtained for these ions are sufficient, the resulting space charge forces can significantly degrade the emittance of the beam components with a lower Q∕A and result for those in a hollow beam. Using a beam viewer and an emittance-measuring device, this paper reports on experimental findings that confirm the existence of such an effect for low charge states of argon. Moreover, by changing the experimental conditions of the ECR plasma in order to modify the charge state distribution of the extracted ion beam, it is shown that the threshold where this space charge effect starts to be significant can be changed.
Neutron powder diffraction studies of sulfuric acid hydrates. II. The structure, thermal expansion, incompressibility, and polymorphism of sulfuric acid tetrahydrate (D2SO4⋅4D2O)
Authors: Fortes A. D. , Wood I. G. , Vočadlo L. , Chapon L. , Knight K. S. , Smith R. I.
Published: February 2008

We report results of the first neutron powder diffraction study of sulfuric acid tetrahydrate (SAT); D2SO4⋅4D2O is tetragonal, space group P4¯21c, with two formula units per unit cell. At 1.7K the unit-cell dimensions are a=b=7.47512(6)Å, c=6.32466(5)Å and V=353.405(5)Å3. At 225K the unit-cell dimensions are a=b=7.4833(1)Å, c=6.4103(1)Å, and V=358.98(1)Å3. The deuteron positions refined from the neutron data are in excellent agreement with the single crystal x-ray analysis of Kjällman and Olovsson [Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. B28, 1692 (1972)]; the structure consists of SO42− and D5O2+ ions hydrogen bonded to form a three dimensional network. Although no structural change is observed between 2K and the melting point at ∼232K, the thermal expansion and incompressibility of the crystal are highly anisotropic. The bulk modulus of SAT at 200K is 9.2(2)GPa, (∂K∕∂P)T=7.9(8), and −(∂K∕∂T)P=10.6(5)MPaK−1, values which are very similar to D2O ice Ih. A new polymorph of SAT has been discovered above 235K at 5.5kbars. The structure of this phase could not be determined, but we have indexed the diffraction pattern with a monoclinic unit cell of likely space-group P21∕a (Z=2). SAT-II has a lower density than SAT-I under the same P∕T conditions; the refined unit-cell parameters at 235K, 5.435kbars are a=6.1902(3)Å, b=11.1234(5)Å, c=5.6446(3)Å, β=110.287(4)°, and V=364.56(2)Å3. This phase has been quenched to low pressures and temperatures, and we have obtained estimates of the thermal expansivity and incompressibility which reveal SAT-II to be significantly stiffer and more isotropic than SAT-I.
Paramagnetic point defects at interfacial layers in biaxial tensile strained (100)Si/SiO2
Authors: Somers P. , Stesmans A. , Afanas’ev V. V. , Claeys C. , Simoen E.
Published: February 2008

A comparative electron spin resonance study is reported on (100)Si/SiO2 entities, grown by thermal oxidation of biaxial tensile strained (100)Si (sSi) layers, epitaxially grown on a strain relaxed Si0.8Ge0.2 buffer layer, and standard (100)Si. In the as-oxidized state a significant decrease (∼50%) of inherently incorporated interface defects, Pb0 and Pb1, is observed, i.e., the sSi/SiO2 interface is found to be inherently significantly improved in terms of electrically detrimental interface traps (Pb0). After vacuum-ultraviolet irradiation two more SiO2-associated defects appear, namely Eγ′ (generic entity O3≡Si·) and EX. Interestingly, a decrease (∼50%) of Eγ′ defect density is observed compared to standard Si/SiO2. This reduction in inherent electrically active interface (Pb0) and near-interface (Eγ′) traps would establish sSi/SiO2 as a superior device structure for all electrical properties where (near)-interfacial traps play a detrimental role. For one, the reduction of detrimental (near)-interface defects may be an additional reason for the commonly reported mobility enhancement in sSi/SiO2 based metal–oxide–semiconductor structures over standard Si/SiO2 ones, and at the same time account for the reported reduction of 1/f noise in the former structures. The data also confirm the generally accepted notion that Pb-type defects are mismatch induced defects.
High electrical resistance composite magnets of Sm2Fe17N3 powders coated with ferrite layer for high frequency applications
Authors: Imaoka N. , Koyama Y. , Nakao T. , Nakaoka S. , Yamaguchi T. , Kakimoto E. , Tada M. , Nakagawa T. , Abe M.
Published: February 2008

This paper describes a novel type of high electrical resistance composite magnet. They were made by compacting or consolidating Sm–Fe–N powders coated with a continuous ferrite layer, which suppresses intergrain conductivity but sustains magnetic exchange interactions among grains. Sm–Fe–N powders (2μm in size) were coated with an “iron ferrite” (an intermediate between magnetite and maghemite) layer by ferrite plating, an aqueous process. They were compacted at 100MPa to form a ferrite/SmFeN composite magnet (note that row Sm–Fe–N powders cannot be consolidated strongly enough to form magnets), and then consolidated to 92–94vol% by the explosive consolidation technique. Coercivity and rectangularity of the compacting composite magnet decreased slightl by 2.0% and 1.4%, respectively, when compared to those of Sm–Fe–N powder compact. We also estimated the resistivity of fully dense ferrite/Sm–Fe–N magnet to be about 4000μΩcm, ten times higher than the estimated value of a fully dense Sm–Fe–N magnet. Thus, the ferrite layer in our composite magnet retains magnetic exchange coupling among Sm–Fe–N grains, and yet suppresses intergrain electrical coupling to increase resistivity. This will decrease eddy current loss and improve high frequency characteristics of composite magnets.
Fabrication and thermoelectric characteristics of [(Bi,Pb)2Ba2O4±w]0.5CoO2 bulks with highly aligned grain structure
Authors: Motohashi T. , Nonaka Y. , Sakai K. , Karppinen M. , Yamauchi H.
Published: February 2008

Here, we report fabrication and thermoelectric characteristics of polycrystalline bulks with aligned grains of the misfit-layered cobalt oxides, [(Bi1−xPbx)2Ba2O4±w]0.5CoO2. High-quality precursor powder was prepared with a spray-drying technique. The precursor was then sintered under a uniaxial pressure to yield dense bulk samples consisting of highly aligned grains. The electrical conductivity of such samples was four times higher than that of conventionally sintered bulks. Accordingly, the thermoelectric characteristics of the grain-aligned specimens were enhanced.
Atomic force microscope cantilever spring constant evaluation for higher mode oscillations: A kinetostatic method
Authors: Tseytlin Yakov M.
Published: February 2008

Our previous study of the particle mass sensor has shown a large ratio (up to thousands) between the spring constants of a rectangular cantilever in higher mode vibration and at the static bending or natural mode vibration. This has been proven by us through the derived nodal point position equation. That solution is good for a cantilever with the free end in noncontact regime and the probe shifted from the end to an effective section and contacting a soft object. Our further research shows that the same nodal position equation with the proper frequency equations may be used for the same spring constant ratio estimation if the vibrating at higher mode cantilever’s free end has a significant additional mass clamped to it or that end is in permanent contact with an elastic or hard measurand object (reference cantilever). However, in the latter case, the spring constant ratio is much smaller (in tens) than in other mentioned cases at equal higher (up to fourth) vibration modes. We also present the spring constant ratio for a vibrating at higher eigenmode V-shaped cantilever, which is now in wide use for atomic force microscopy. The received results on the spring constant ratio are in good (within a few percent) agreement with the theoretical and experimental data published by other researchers. The knowledge of a possible spring constant transformation is important for the proper calibration and use of an atomic force microscope with vibrating cantilever in the higher eigenmodes for measurement and imaging with enlarged resolution.
Microstructural evolution in m-plane GaN growth on m-plane SiC
Authors: Sun Qian , Kwon Soon-Yong , Ren Zaiyuan , Han Jung , Onuma Takeyoshi , Chichibu Shigefusa F. , Wang Shaoping
Published: February 2008

This letter presents a study on the nucleation and microstructural evolution of m-plane GaN epilayers on m-plane SiC substrates using high-temperature AlN buffer layers. Controlled growth interruptions were carried out to render snapshots of heteroepitaxial dynamics. It was discovered that island coalescence results in an inhomogeneous mosaic tilt along the c-axis. Mesoscopic study of nucleation evolution helps elucidate the origin of commonly observed surface undulation and striation, which is attributed to concave growth due to the coalescence of trapezoidal islands upon contact. A model correlating microstructural defects with optical properties is proposed to explain the observed pattern in spatially resolved cathodoluminescence mapping.
Giant magnetoelectric effect in Ni–lead zirconium titanate cylindrical structure
Authors: Pan D. A. , Bai Y. , Volinsky Alex A. , Chu W. Y. , Qiao L. J.
Published: February 2008

The magnetoelectric (ME) coupling of a bilayered Ni–lead zirconate titanate composite structure synthesized by electrodeposition was studied in this paper. The ME voltage coefficient was measured in the range of 1–120kHz as the bias field is parallel to the axial. The results indicate that an electromechanical resonance appears at 59.9kHz. The bilayered cylindrical ME composite exhibits a special field dependence of ME coefficient. Either for the resonant state or the nonresonant state, above 1kOe, the ME voltage coefficient increased linearly with the strengthening of bias field, up to 30V∕cmOe at 8kOe.
Structures and magnetic properties of (Fe, Li)-codoped NiO thin films
Authors: Yan Wensheng , Weng Weixiang , Zhang Guobin , Sun Zhihu , Liu Qinghua , Pan Zhiyun , Guo Yuxian , Xu Pengshou , Wei Shiqiang , Zhang Yunpeng , Yan Shishen
Published: February 2008

Rock-salt structured single-phase Ni0.98Fe0.02O and Ni0.93Fe0.02Li0.05O thin films with room temperature ferromagnetism were grown by pulsed laser deposition. It is found that the Li codoping into Ni0.98Fe0.02O significantly increases the saturation magnetic moment by a factor of 2, i.e., from 0.32μB∕Fe rising to 0.67μB∕Fe. The x-ray absorption fine structure spectral analyses at Fe and O K edge reveal that in both samples, the impurities are substitutionally incorporated into the NiO host. The first-principles calculations show that substitutionally doping Li ions into NiO leads to a strong hybridization between the Fe 3d states and the spin-split acceptor band at the Fermi level. As a result, the Fe 3d electron configuration is altered and the effective magnetic moment per Fe ion is enhanced.
Blue-light emission from GaN∕Al0.5Ga0.5N quantum dots
Authors: Huault T. , Brault J. , Natali F. , Damilano B. , Lefebvre D. , Nguyen L. , Leroux M. , Massies J.
Published: February 2008

The growth by molecular beam epitaxy and the optical properties of GaN∕Al0.5Ga0.5N quantum dots on (0001) sapphire substrates are reported. The quantum dots are spontaneously formed via a two dimensional to three dimensional transition upon growth interruption. Photoluminescence over the blue range (435–470nm) is obtained at room temperature by varying the GaN nominal thickness. A weak temperature dependence of the integrated photoluminescence intensity between low temperature and room temperature is observed indicating strong carrier localization in the quantum dots.