bluuebunny/crossref_metadata_2025 huggingface dataset:
Movement of Amazon surface water from time‐variable satellite gravity measurements and implications for water cycle parameters in land surface models
Authors: Han Shin‐Chan , Yeo In‐Young , Alsdorf Doug , Bates Paul , Boy Jean‐Paul , Kim Hyungjun , Oki Taikan , Rodell Matthew
Published: September 2010

The large‐scale observations of terrestrial water storage from GRACE satellites over the Amazon are analyzed with land surface model (LSM) outputs of runoff and soil moisture. A simple yet effective runoff routing method based on a continuity equation is implemented to model horizontal transport of surface water within the Amazon basin. The GRACE observations are analyzed separately for soil moisture and surface water storages (generated from runoff), relying on their distinct spatial patterns, being disperse for soil moisture and localized for surface water. Various effective velocities for storage transport are tested against the GRACE observations. When the model runoff is routed with an uniform velocity of 30 cm/s, the annual variation of the resulting surface water storage is generally found to be larger than the satellite measurements and ground gauge data by a factor of 1.5 or higher. The peak annual anomaly of surface water storage is observed around the midstream of the Amazon main stem. However, the runoff routing simulations present the peak amplitude consistently around the delta (downstream), unless the increasing velocity in a downstream region is used. As complements to the ground gauge data, the satellite observations provide unique ‘spatial’ information of water cycle parameters. Our analysis indicates possible shortcomings in the certain LSM mass transport scheme between atmosphere and land surface, particularly the production of too large seasonal variations in runoff (and maybe too little variations in evapotranspiration), and the dynamic characteristics of surface water transport within the Amazon basins.
Bottom topography and roughness variations as triggering mechanisms to the formation of sorted bedforms
Authors: Van Oyen T. , de Swart H. E. , Blondeaux P.
Published: September 2010

A new model is presented that addresses the occurrence of sorted bedforms on inner shelves of coastal seas. These features consist of alternating bands of coarse and fine grains, with small topographic undulations. We show that inherent feedbacks between alongshore currents, sea waves, bottom topography and roughness variations result in the emergence of morphological patterns, similar to the observed bed features. We find that two modes are amplified which display different characteristics, yielding a possible explanation to the diversity exhibited by sorted bedforms in the field. The results illustrate that both roughness variations and bottom topography influence the generation of sorted bedforms.
How ocean color can steer Pacific tropical cyclones
Authors: Gnanadesikan Anand , Emanuel Kerry , Vecchi Gabriel A. , Anderson Whit G. , Hallberg Robert
Published: September 2010

Because ocean color alters the absorption of sunlight, it can produce changes in sea surface temperatures with further impacts on atmospheric circulation. These changes can project onto fields previously recognized to alter the distribution of tropical cyclones. If the North Pacific subtropical gyre contained no absorbing and scattering materials, the result would be to reduce subtropical cyclone activity in the subtropical Northwest Pacific by 2/3, while concentrating cyclone tracks along the equator. Predicting tropical cyclone activity using coupled models may thus require consideration of the details of how heat moves into the upper thermocline as well as biogeochemical cycling.
Distribution of seismic wave speed changes associated with the 12 May 2008 Mw 7.9 Wenchuan earthquake
Authors: Chen Jiu Hui , Froment Bérénice , Liu Qi Yuan , Campillo Michel
Published: September 2010

We used continuous recordings in Sichuan, China to track the temporal change of the seismic wave speed at a regional scale, for 2 years including the Wenchuan Mw 7.9 earthquake. The data are recorded by a temporary network of 156 broad‐band seismographs in a region that covers the southern 2/3 of the fault activated during the earthquake. A doublet analysis applied on the codas of seismic noise cross correlation functions is used to detect temporal velocity changes. We found clear evidence that the seismic velocity drops by up to 0.08% in the fault region just after the earthquake with fluctuations within 0.02% before the earthquake. We compared the measurements in different sub‐arrays to get a spatial distribution of the velocity changes. This distribution is consistent with the volumetric strain change during the Wenchuan earthquake and shows that the co‐seismic velocity change is not controlled by the response of sediments.
Historical trends in Southern Ocean storminess: Long‐term variability of extreme wave heights at Cape Sorell, Tasmania
Authors: Hemer Mark A.
Published: September 2010

Atmospheric re‐analyses indicate increased Southern Ocean (SO) storminess over the past few decades. A southern Australia waverider record provides a 23‐year record of storm waves generated in the SO. Statistical models to estimate long‐term trends in frequency and intensity of severe storm waves, based on time‐dependent versions of the Peak over Threshold model, are applied to investigate SO storminess trends. Significant increase in frequency of storm wave events observed in the corrected ERA‐40 re‐analysis significant wave height (HS) record is supported by increasing frequency of synoptic storms which drive large wave events at the site in both ERA‐40 and NCEP‐NCAR re‐analyses. However buoy data show a small decrease in storm wave event frequency, consistent with previous studies investigating trends in SO mean HS from altimeter records. Re‐analysis winds, with apparent increasing trend, may have influenced prior SO research conclusions, particularly related to weakening of the SO CO2 sink.
Ionospheric holes made by ballistic missiles from North Korea detected with a Japanese dense GPS array
Authors: Ozeki Masaru , Heki Kosuke
Published: September 2010

A dense array of global positioning system (GPS) receivers is a useful tool to study ionospheric disturbances. Here we report observations by a Japanese GPS array of ionospheric holes, i.e., localized electron depletion. They were made by neutral molecules in exhaust plumes (e.g., water) of ballistic missiles from North Korea, Taepodong‐1 and ‐2, launched on 31 August, 1998, and 5 April, 2009, respectively. Negative anomaly of electron density emerged ∼6 min after the launches in the middle of the Japan Sea, and extended eastward along the missile tracks. By comparing the numerical simulation of electron depletion and the observed change in ionospheric total electron content, we suggest that the exhaust plumes from the Taepodong‐2 second stage effused up to ∼1.5 × 1026 water molecules per second. The ionospheric hole signature was used to constrain the Taepodong‐2 trajectory together with other information, e.g., coordinates of the launch pad, time and coordinates of the first stage splashdown, and height and time of the second stage passage over Japan. The Taepodong‐2 is considered to have reached the ionospheric F region in ∼6 min, flown above northeastern Japan ∼7 min after the launch, and crashed to the Pacific Ocean without attaining the first astronautical velocity. The ionospheric hole in the 1998 Taepodong‐1 launch was much less in size, but it is difficult to compare directly the thrusts of the two missiles due to uncertainty of the Taepodong‐1 trajectory.
Energy‐Restricted High‐Fat Diets Only Partially Improve Markers of Systemic and Adipose Tissue Inflammation
Authors: Kalupahana Nishan S. , Voy Brynn H. , Saxton Arnold M. , Moustaid‐Moussa Naima
Published: September 2010

This study aimed at investigating whether the weight loss due to energy‐restricted high‐fat diets is accompanied with parallel improvements in metabolic markers and adipose tissue inflammation. Eight‐week‐old C57BL/6J mice were given free access to a low‐fat (LF) or a high‐fat (45% of energy from fat—HF) diet for 6 months. Restricting intake of the HF diet by 30% (HFR) during the last 2 months of the HF feeding trial decreased fasting plasma insulin, homeostasis model assessment of insulin resistance (HOMAIR), and plasma triglyceride levels and improved hepatic steatosis compared to ad libitum HF feeding, indicating an improved metabolic profile. Further, analysis of gonadal white adipose tissue (GWAT) gene expression by microarray and quantitative PCR analyses demonstrated that HFR downregulated expression of genes linked to cell and focal adhesion, cytokine‐cytokine receptor interaction, and endoplasmic reticulum (ER)–associated degradation pathway. However, HFR had no effect on circulating plasminogen activator inhibitor‐1 (PAI‐1) and nonesterified fatty acid levels, which were persistently higher in both HF and HFR groups compared to the LF group. Furthermore, HFR had a negative effect on plasma total adiponectin level. Finally, while HFR decreased GWAT monocyte chemotactic protein‐1 (MCP‐1), interleukin‐2 (IL‐2), and PAI‐1 levels, it did not affect several other cytokines including granulocyte‐macrophage colony‐stimulating factor, interferon‐γ, IL‐1β, IL‐6, and IL‐10. In summary, energy‐restricted high‐fat diets improve insulin sensitivity, while only partially improving markers of systemic and adipose tissue inflammation. In conclusion, our study supports the recommended low‐fat intake for overall cardiovascular health.
DPP4Gene DNA Methylation in the Omentum is Associated With Its Gene Expression and Plasma Lipid Profile in Severe Obesity
Authors: Turcot Valérie , Bouchard Luigi , Faucher Geneviève , Tchernof André , Deshaies Yves , Pérusse Louis , Bélisle Alexandre , Marceau Simon , Biron Simon , Lescelleur Odette , Biertho Laurent , Vohl Marie‐Claude
Published: September 2010

Severely obese subjects with the metabolic syndrome (MS) have higher dipeptidyl peptidase‐4 (DPP4) expression in their visceral adipose tissue (VAT) compared to obese individuals without MS. We tested the hypothesis that methylation level of CpG sites in theDPP4promoter CpG island in VAT was genotype‐dependent and associated withDPP4mRNA abundance and MS‐related phenotypes. The VAT DNA was extracted in 92 severely obese premenopausal women undergoing biliopancreatic derivation for the treatment of obesity. Women were nondiabetic and none of them used medication to treat MS features. Cytosine methylation rates (%) of 102 CpG sites in theDPP4CpG island were assessed by pyrosequencing of sodium bisulfite‐treated DNA. Methylation rates were >10% for CpG sites 94–102. Their mean methylation rate (%Meth94–102) was different between genotypes forDPP4polymorphisms rs13015258 (P= 0.001), rs17848915 (P= 0.0004), and c.1926 G>A (P= 0.001). The %Meth94–102correlated negatively withDPP4mRNA abundance (r= −0.25,P< 0.05) and positively with plasma high‐density lipoprotein (HDL) cholesterol concentrations (r= 0.22,P< 0.05), whereasDPP4mRNA abundance correlated positively with plasma total‐/HDL‐cholesterol ratio (r= 0.25;P< 0.05). In the VAT of nondiabetic severely obese women, genotype‐dependent methylation levels of specific CpG sites in theDPP4promoter CpG island were associated withDPP4gene expression and variability in the plasma lipid profile. HigherDPP4gene expression in VAT and its relationship with the plasma lipid profile may be explained by actually unknown DPP4 biological effect or, to another extent, may also be a marker of VAT inflammation known to be associated with metabolic disturbances.
A Potential Role for 5‐Androstene‐3β,7β,17β‐triol in Obesity and Metabolic Syndrome
Authors: Auci Dominick L. , Ahlem Clarence N. , Kennedy Michael R. , Page Theodore M. , Reading Christopher L. , Frincke James M.
Published: September 2010

Metabolic syndrome is marked by perturbed glucocorticoid (GC) signaling, systemic inflammation, and altered immune status. Dehydroepiandrosterone (DHEA), a major circulating adrenal steroid and dietary supplement, demonstrates antiobesity, anti‐inflammatory, GC‐opposing and immune‐modulating activity when administered to rodents. However, plasma DHEA levels failed to correlate with metabolic syndrome and oral replacement therapy provided only mild benefits to patients. Androstene‐3β,7β,17β‐triol (β‐AET) an anti‐inflammatory metabolite of DHEA, also exhibits GC‐opposing and immune‐modulating activity when administered to rodents. We hypothesized a role for β‐AET in obesity. We now report that plasma levels of β‐AET positively correlate with BMI in healthy men and women. Together with previous studies, the observations reported here may suggest a compensatory role for β‐AET in preventing the development of metabolic syndrome. The β‐AET structural core may provide the basis for novel pharmaceuticals to treat this disease.
Correlates of Participation in a Pediatric Primary Care‐Based Obesity Prevention Intervention
Authors: Taveras Elsie M. , Hohman Katherine H. , Price Sarah N. , Rifas‐Shiman Sheryl L. , Mitchell Kathleen , Gortmaker Steven L. , Gillman Matthew W.
Published: September 2010

The purpose of this study was to examine the correlates of participation in a childhood obesity prevention trial. We sampled parents of children recruited to participate in a randomized controlled trial. Eligible children were 2.0–6.9 years with BMI ≥95th percentile or 85th to <95th percentile if at least one parent was overweight. We attempted contact with parents of children who were potentially eligible. We recruited 475 parents via telephone following an introductory letter. We also interviewed 329 parents who refused participation. Parents who refused participation (n = 329) did not differ from those who participated (n = 475) by number of children at home (OR 0.94 per child; 95% CI: 0.77–1.15) or by child age (OR 1.07 per year; 95% CI: 0.95–1.20) or sex (OR 1.06 for females vs. males; 95% CI: 0.80–1.41). After multivariate adjustment, parents who were college graduates vs. <college graduates were less likely to participate (OR 0.62; 95% CI: 0.46–0.83). In addition, parents were less likely (OR 0.41; 95% CI: 0.31–0.56) to participate if their child was overweight vs. obese. Among the 115 refusers with obese children, 21% cited as a reason for refusal that their children did not have a weight problem, vs. 30% among the 214 refusers with overweight children. In conclusion, parents of preschool‐age children with a BMI 85–95th%ile are less likely to have their children participate in an obesity prevention trial than parents of children with BMI >95th%ile. One reason appears to be that they less frequently consider their children to have a weight problem.
Energy Crops for the Production of Biofuels
Authors: Montross Michael , Crofcheck Czarena
Published: September 2010

Numerous options are available to supply biomass to biorefineries. Potential feedstocks include short rotation woody crops, herbaceous energy crops, and residues (forestry and agricultural). Each feedstock has unique chemical and physical properties that will influence the products and profitability from a biorefinery. For example, herbaceous feedstocks will have higher ash contents on average than woody products. Herbaceous feedstocks typically will have a lower lignin content and as a result a lower heating value than woody crops. Feedstock selection should consider the availability of equipment to establish, maintain, and harvest energy crops. In most cases, the equipment required is available to produce energy crops within the forestry and agricultural industries but is not optimized for energy crop production. Deciding which feedstock to produce will depend on site-specific considerations (soil type, temperature, and rainfall) that will influence the cost, yield, and composition of energy crops. Collection, storage, and transportation of energy crops is expensive relative to current fossil fuels, although biomass energy crops have lower greenhouse gas emissions than fossil fuels.
Fast Pyrolysis of Biomass for Energy and Fuels
Authors: Bridgwater A. V.
Published: September 2010

Bioenergy is now accepted as having the potential to provide the major part of the projected renewable energy provisions of the future as biofuels in the form of gas, liquid or solid fuels or electricity and heat. There are three main routes to providing these biofuels — thermal conversion, biological conversion and physical conversion — all of which employ a range of chemical reactor configurations and process designs. This paper focuses on fast pyrolysis from which the liquid, often referred to as bio-oil, can be used on-site or stored or transported to centralised and/or remote user facilities for utilisation for example as a fuel, or further processing to biofuels and/or chemicals. This offers the potential for system optimisation, much greater economies of scale and exploitation of the concepts of biorefineries. The technology of fast pyrolysis is described, particularly the reactors that have been developed to provide the necessary conditions to optimise performance. The primary liquid product is characterised, as well as the secondary products of electricity and/or heat, liquid fuels and a considerable number of chemicals. The main technical and non-technical barriers to the market deployment of the various technologies are identified and briefly discussed.
Ionic Liquids for the Utilization of Lignocellulosics
Authors: Morton Samuel A. , Morton Laurel A.
Published: September 2010

Given the ever increasing world-wide demand for energy, coupled with the instability of current petroleum resources, the development of sustainable, biologically-derived energy and commodity chemical feedstock sources is critical. A great deal of interest and effort is currently being focused on the development of technologies to convert lignocellulosic material (“woody” biomass) into renewable replacements and augments for current petroleum-derived platform chemicals and fuels. These technologies must address the challenge of “biomass recalcitrance” – the natural resistance plant matter exhibits to biodegradation. Recently, a novel class of compounds, ionic liquids, has been presented as a possible solution to the challenge of biomass recalcitrance. These compounds have demonstrated the ability to dissolve either the entirety of the lignocellulosic biomass or the individual fractions selectively. While the potential for ionic liquids to serve as solvents for the chemical and biochemical processing of biomass is high, the body of scientific knowledge is still in the early stages of exploration and many challenges remain to be resolved. The purpose of this article is to provide a “state-of-the-art” review of the scientific literature and to identify trends that are developing and issues that remain.
Conversion of Cellulose to Sugars
Authors: Guha Samar Kumar , Kobayashi Hirokazu , Fukuoka Atsushi
Published: September 2010

Cellulose is the most abundant biopolymer synthesized in Nature. It is the main constituent of plant cells and significantly less expensive than cereals. Cellulose is a water-insoluble long-chain polysaccharide consisting of several hundred to thousands of D-glucose molecules of formal composition (C6H10O5)n and can be hydrolyzed to soluble sugars by various methods. The traditional acidic and enzymatic methods have a number of limitations, although the sugars are obtained in high yields in some cases. Due to their environmentally friendly behavior, recently developed heterogeneous catalysts are significant candidates for the depolymerization of cellulose into sugars. The major advantages of the catalytic conversion of cellulose are high activity and selectivity and easy separation of products from the reaction mixture. The sugars formed from cellulose have a wide range of applications as fuels and chemicals in chemical industries.
Conversion of Carbohydrates to Liquid Fuels
Authors: Akien Geoffrey , Qi Long , Horváth István T.
Published: September 2010

The most important carbohydrate-containing biomass resources and oxygen-containing liquid fuels are summarized. After the overview of potential strategies to convert carbohydrates to oxygenates, the current status of the conversion technologies for ethanol and butanol are discussed.
Plasmin on adherent cells: from microvesiculation to apoptosis
Authors: Doeuvre Loïc , Plawinski Laurent , Goux Didier , Vivien Denis , Anglés-Cano Eduardo
Published: September 2010

Cell activation by stressors is characterized by a sequence of detectable phenotypic cell changes. A given stimulus, depending on its strength, induces modifications in the activity of membrane phospholipid transporters and calpains, which lead to phosphatidylserine exposure, membrane blebbing and the release of microparticles (nanoscale membrane vesicles). This vesiculation could be considered as a warning signal that may be followed, if the stimulus is maintained, by cell detachment-induced apoptosis. In the present study, plasminogen incubated with adherent cells is converted into plasmin by constitutively expressed tPA (tissue-type plasminogen activator) or uPA (urokinase-type plasminogen activator). Plasmin formed on the cell membrane then induces a unique response characterized by membrane blebbing and vesiculation. Hitherto unknown for plasmin, these membrane changes are similar to those induced by thrombin on platelets. If plasmin formation persists, matrix proteins are then degraded, cells lose their attachments and enter the apoptotic process, characterized by DNA fragmentation and specific ultrastructural features. Since other proteolytic or inflammatory stimuli may evoke similar responses in different types of adherent cells, the proposed experimental procedure can be used to distinguish activated adherent cells from cells entering the apoptotic process. Such a distinction is crucial for evaluating the effects of mediators, inhibitors and potential therapeutic agents.
Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. III. Colonization by birds
Authors: Schipper Clinton , Shanahan Mike , Cook Simon , Thornton Ian W. B.
Published: September 2010

Location, AimLong Island, 55 km north of New Guinea, erupted explosively in the seventeenth century and has been recolonized by animals and plants. Effectively in 1968, an island, Motmot, emerged from Long's 13 km‐diameter fresh‐water caldera lake, about 4 km from the nearest shore. A nested pair of colonization sequences is thus available for study. Long Island has been recolonized by birds, and Motmot has been colonized, presumably from the surrounding ring of Long Island. In order to monitor further colonization of Long Island following bird surveys in 1933 and 1972, and to survey the birds of Motmot, Motmot and the western parts of Long were visited for 15 days in 1999.

ResultsIn the last 66 years one species probably has become extinct; in the past 27 years three species have colonized and three, present in 1972, were not recorded in 1999. We assess the present number of nonmigrant land bird species as fifty. On Motmot, we recorded eight species, three breeding, and found two more only as prey remains (three raptor species were seen on the island).

Main conclusionsLong Island's avifauna still has youthful features. Species with good colonizing ability predominate, and there are no island‐endemic subspecies. There is a persistently high proportion of supertramps; none of the ten supertramps has been replaced by later‐colonizing ‘high‐S' species. A quasi‐equilibrium of about fifty species, fourteen fewer than the predicted equilibrium number for the island, has persisted for at least seven decades and may be seen as that appropriate to the present prolonged stage of Long's floral and vegetational development. Compared with the younger avifauna of Krakatau, Long's avifauna has a higher proportion of nectarivores, predators of large invertebrates and small vertebrates, and ground‐foraging insectivore‐herbivores, and a lower proportion of the insectivore‐frugivore guild. Motmot's small avifauna consists predominantly of species obtaining subsistence from outside the island.
Characterization of a CD46 transgenic pig and protection of transgenic kidneys against hyperacute rejection in non‐immunosuppressed baboons
Authors: Loveland Bruce E. , Milland Julie , Kyriakou Peter , Thorley Bruce R. , Christiansen Dale , Lanteri Marc B. , van Regensburg Mark , Duffield Maureen , French Andrew J. , Williams Lindsay , Baker Louise , Brandon Malcolm R. , Xing Pei‐Xiang , Kahn Del , McKenzie Ian F.C.
Published: September 2010

Abstract:  Human membrane cofactor protein (CD46) controls complement activation and when expressed sufficiently as a transgene protects xenografts against complement‐mediated rejection, as shown here using non‐immunosuppressed baboons and heterotopic CD46 transgenic pig kidney xenografts. This report is of a carefully engineered transgene that enables high‐level CD46 expression. A novel CD46 minigene was validated by transfection and production of a transgenic pig line. Pig lymphocytes were tested for resistance to antibody and complement‐mediated lysis, transgenic tissues were characterized for CD46 expression, and kidneys were transplanted to baboons without immunosuppression. Absorption of anti‐Galα(1,3)Gal epitope (anti‐GAL) serum antibodies was measured. Transgenic pigs expressed high levels of CD46 in all tissues, especially vascular endothelium, with stable expression through three generations that was readily monitored by flow cytometry of transgenic peripheral blood mononuclear cells (PBMC). Transgenic PBMC pre‐sensitized with antibody were highly resistant to human complement‐mediated lysis which readily lysed normal pig PBMC. Normal pig kidneys transplanted without cold ischemia into non‐immunosuppressed adult baboons survived a median of 3.5 h (n = 7) whereas transgenic grafts (n = 9), harvested at ∼24‐h intervals, were either macroscopically normal (at 29, 48 and 68 h) or showed limited macroscopic damage (median > 50 h). Microscopic assessment of transplanted transgenic kidneys showed only focal tubular infarcts with viable renal tissue elsewhere, no endothelial swelling or polymorph adherence and infiltration by lymphocytes beginning at 3 days. Coagulopathy was not a feature of the histology in four kidneys not rejected and assessed at 48 h or later after transplantation. Baboon anti‐GAL serum antibody titers were high before transplantation and, in one extensively analyzed recipient, reduced ∼8‐fold within 5.5 h. The data demonstrate that a single CD46 transgene controls hyperacute kidney graft rejection in untreated baboons despite the presence of antibody and complement deposition. The expression levels, tissue distribution and in vitro functional tests indicate highly efficient CD46 function, controlling both classical and alternative pathway complement activation, which suggests it might be the complement regulator of choice to protect xenografts.
Hydrodynamic coupling of spherical particles to a planar fluid-fluid interface: Theoretical analysis
Authors: Bławzdziewicz J. , Ekiel-Jeżewska M. L. , Wajnryb E.
Published: September 2010

We have developed a new technique (based on our Cartesian-representation method) to describe hydrodynamic interactions of a spherical particle with an undeformable planar fluid-fluid interface under creeping-flow conditions. The interface can be either surfactant-free or covered with an incompressible surfactant monolayer. We consider the effect of surface incompressibility and surface viscosity on particle motion. The new algorithm allows to calculate particle mobility coefficients for hydrodynamically coupled particles, moving either on the same or on the opposite sides of the interface.
Plasma sheath criterion in thermal electronegative plasmas
Authors: Ghomi Hamid , Khoramabadi Mansour , Shukla Padma Kant , Ghorannevis Mahmod
Published: September 2010

The sheath formation criterion in electronegative plasma is examined. By using a multifluid model, it is shown that in a collisional sheath there will be upper as well as lower limits for the sheath velocity criterion. However, the parameters of the negative ions only affect the lower limit.
Harvesting single ferroelectric domain stressed nanoparticles for optical and ferroic applications
Authors: Cook G. , Barnes J. L. , Basun S. A. , Evans D. R. , Ziolo R. F. , Ponce A. , Reshetnyak V. Yu. , Glushchenko A. , Banerjee P. P.
Published: September 2010

We describe techniques to selectively harvest single ferroelectric domain nanoparticles of BaTiO3 as small as 9 nm from a plethora of nanoparticles produced by mechanical grinding. High resolution transmission electron microscopy imaging shows the unidomain atomic structure of the nanoparticles and reveals compressive and tensile surface strains which are attributed to the preservation of ferroelectric behavior in these particles. We demonstrate the positive benefits of using harvested nanoparticles in disparate liquid crystal systems.
Note: Scanned multi-light-emitting-diode illumination for volumetric particle image velocimetry
Authors: Patterson M. D. , Wettlaufer J. S.
Published: September 2010

We describe the development of both multilevel two-dimensional and grid-based three-dimensional illumination systems for volumetric particle image velocimetry (PIV) that uses a single camera and an arbitrary number of low powered lasers. This flexible system is robust and capable of capturing results over a range of spatiotemporal scales determined by the choice of camera, the depth of field of the lens, and the laser power. The system is demonstrated on a rotating spin-up experiment where we extract high fidelity velocity fields at up to 62 frames/s at a spatial resolution of 2352×1728 pixels. The flexibility and economy offered by this system—approximately one-tenth that of a comparable commercial package—may make it attractive to many laboratory users.
Kinetic and thermodynamic studies of the fragility of bulk metallic glass forming liquids
Authors: Gallino Isabella , Schroers Jan , Busch Ralf
Published: September 2010

The thermodynamic functions of the bulk metallic glass (BMG) forming Pd43Ni10Cu27P20 alloy are determined calorimetrically as a function of temperature. Along with eight other BMG forming alloys, the available experimental thermodynamic and viscosity data are reassessed. For each alloy, consistent Vogel–Fulcher–Tammann (VFT) fits of the viscosity measurements are established, and the temperature dependence of the configurational entropy is calculated from thermodynamic data. Together with the VFT fits, fits to the Adam–Gibbs equation are performed using this configurational entropy change. We find remarkable agreement between the Adam–Gibbs and VFT fits. Moreover, the temperature T0 is obtained from the VFT fits at which the viscous flow diverges. This T0 matches very well the temperature where the configurational entropy vanishes in the corresponding Adam–Gibbs fits.
Surface dielectric relaxation: Probing technique and its application to thermal activation dynamics of polymer surface
Authors: Ishii Masashi
Published: September 2010

For dynamic analyses of a polymer surface, a dielectric relaxation measurement technique with parallel electrodes placed away from the surface was developed. In this technique, a liquid heating medium was filled in the space between the polymer surface and the electrodes. The construction that maintains the surface can clarify the physical interactions between the liquid and the bare surface and controlling the temperature of the liquid reveals the thermal activation property of the surface. The dielectric relaxation spectrum of the surface convoluted into the bulk and liquid spectra can be obtained by a reactance analysis and the surface spectrum is expressed with an equivalent resistance-capacitance parallel circuit. On the basis of the electromechanical analogy, the electric elements can be converted into mechanical elements that indicate the viscoelasticity of the polymer surface. Using these measurement and analysis techniques, the electric and mechanical properties of the surface of a gelatinized chloroprene rubber sample were analyzed.
Drift wave instability analysis in pair-ion-electron plasmas using kinetic approach
Authors: Ali S. , Saleem H.
Published: September 2010

Drift wave is studied in pair-ion plasmas in the presence of electrons using the Vlasov–Poisson set of equations. The growth rate of this universal instability depends on the concentration of electrons. The real frequency and the growth rate are reduced as the number density of electrons decreases. If the laboratory produced pair-ion plasmas contain relatively small amount of electrons then very low frequency almost stable drift waves can be produced which will indicate that the plasma is not a pure pair-ion plasma. The present investigation can be useful for future experiments on pair-ion plasmas and low density low temperature industrial plasmas which contain negative ions.
Heterogeneous nucleation and metal-insulator transition in epitaxial films of NdNiO3
Authors: Kumar Devendra , Rajeev K. P. , Kushwaha A. K. , Budhani R. C.
Published: September 2010

We have investigated the temperature driven first order metal-insulator (M-I) transition in thin films of NdNiO3 and have compared it with the bulk behavior. The M-I transition of thin films is sensitive to epitaxial strain and its partial relaxation creates an inhomogeneous strain field in the films which broadens the M-I transition. Both the thin film and the bulk samples exhibit nonequilibrium features in the transition regime which are attributed to the presence of high temperature metallic phases in their supercooled state. The degree of supercooling in the thin films is found to be much smaller than in the bulk which suggests that the M-I transition in the thin film occurs through heterogeneous nucleation.
Ions in water: Role of attractive interactions in size dependent diffusivity maximum
Authors: Borah Bhaskar J. , Yashonath S.
Published: September 2010

A molecular dynamics study of model ions in water is reported. The van der Waals diameter of both the cations and anions is varied. We have carried out two sets of simulations—with and without dispersion interaction—between the ion and water. Self-diffusivity of the ions exhibits an anomalous maximum as a function of the van der Waals diameter for both these sets. This existence of a maximum in self-diffusivity when there is no dispersion interaction between the ion and the water is attributed to the attractive term from electrostatic interactions. Detailed analysis of this effect shows that the solvent shell is more strongly defined in the presence of dispersion interactions. A smaller ion exhibits biexponential decay while a single exponential decay is seen for the ion with maximum diffusivity in the self-part of the intermediate scattering function. The solvent structure around the ion appears to determine much of the dynamics of the ion. Interesting trends are seen in the activation energies and these can be understood in terms of the levitation effect.
Single quantum dot nanowire photodetectors
Authors: van Kouwen M. P. , van Weert M. H. M. , Reimer M. E. , Akopian N. , Perinetti U. , Algra R. E. , Bakkers E. P. A. M. , Kouwenhoven L. P. , Zwiller V.
Published: September 2010

We report InP nanowire photodetectors with a single InAsP quantum dot as light absorbing element. With excitation above the InP band gap, the nanowire photodetectors are efficient (quantum efficiency of 4%). Under resonant excitation of the quantum dot, the photocurrent amplitude depends on the linear polarization direction of the incident light. The photocurrent is enhanced (suppressed) for a polarization parallel (perpendicular) to the axis of the nanowire (contrast 0.83). The active detection volume under resonant excitation is 7×103 nm3. These results show the promising features of quantum dots embedded in nanowire devices for electrical light detection at high spatial resolution.
Incorporation of Cu acceptors in ZnO nanocrystals
Authors: Oo W. M. Hlaing , McCluskey M. D. , Huso J. , Morrison J. L. , Bergman L. , Engelhard M. H. , Saraf L. V.
Published: September 2010

Doping of semiconductor nanocrystals is an important problem in materials research. Using infrared and x-ray photoelectron spectroscopy, we have observed Cu acceptor dopants that were intentionally introduced into ZnO nanocrystals during growth. The incorporation of Cu2+ dopants increased as the average diameter of the nanocrystals was increased from ∼3 to 6 nm. Etching the nanocrystals with acetic acid revealed a core-shell structure, where a lightly doped core is surrounded by a heavily doped shell. These observations are consistent with the trapped dopant model, in which dopant atoms stick to the surface of the core and are overgrown by the nanocrystal material.
Insulator-quantum Hall conductor transition in high electron density gated InGaAs/InAlAs quantum wells
Authors: Gao K. H. , Yu G. , Zhou Y. M. , Wei L. M. , Lin T. , Shang L. Y. , Sun L. , Yang R. , Zhou W. Z. , Dai N. , Chu J. H. , Austing D. G. , Gu Y. , Zhang Y. G.
Published: September 2010

We study the insulator-quantum Hall conductor transition in two high-density gated InGaAs/InAlAs quantum well samples. We observe a well-defined critical magnetic field and verify this marks a genuine phase transition by investigating the scaling behavior of the longitudinal resistivity with field and temperature at fixed electron density. Consistent with prevailing experimental results the critical field decreases with increasing electron density in one sample (QW0710). In the other sample (QW0715), with higher delta doping density, however, we unexpectedly find that the critical field increases with increasing electron density. This unexpected behavior may be the result of the system entering the classical percolation regime.
Reaction pathway analysis for dislocation nucleation from a sharp corner in silicon: Glide set versus shuffle set
Authors: Shima Koichi , Izumi Satoshi , Sakai Shinsuke
Published: September 2010

Using reaction pathway sampling, we have investigated the shear stress dependences of the activation energies of shuffle-set and glide-set dislocation nucleation from a sharp corner in silicon. The gradient of the glide-set dislocation curve is lower than that of the shuffle-set dislocation, and the athermal stress of glide-set dislocation is largely higher than that of shuffle-set dislocation. As a result, the two curves have a cross point, which means that shuffle-set dislocation is likely nucleated at high stress and low temperature and glide-set dislocation is likely nucleated at low stress and high temperature. Our result clearly explains the mechanism of recent molecular dynamics on these two types of dislocation nucleation at different temperatures and stress regimes. With increased compressive stress on the slip plane, the activation energy of the shuffle-set dislocation nucleation is greatly decreased, while that of glide-set dislocation nucleation is slightly increased. That would explain why shuffle-set dislocations were found under compressive stress fields.
Observation of electron confinement in InP/GaAs type-II ultrathin quantum wells
Authors: Singh S. D. , Dixit V. K. , Porwal S. , Kumar Ravi , Srivastava A. K. , Ganguli Tapas , Sharma T. K. , Oak S. M.
Published: September 2010

The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.
λ
∼
3.36

μ
m
room temperature InGaAs/AlAs(Sb) quantum cascade lasers with third order distributed feedback grating
Authors: Commin J. P. , Kennedy K. , Revin D. G. , Zhang S. Y. , Krysa A. B. , Cockburn J. W.
Published: September 2010

We report on the development of strain compensated InGaAs/AlAs(Sb) quantum cascade lasers, incorporating a buried third order distributed feedback grating. Single mode operation with a side mode suppression ratio of ∼30 dB has been achieved in the wavelength range of 3.358–3.380 μm for temperatures between 270 and 360 K. The threefold increase in grating pitch size, compared with a first order grating, allows conventional photolithographic techniques to be used for single mode laser fabrication.
Picosecond optical spectroscopy of a single negatively charged self-assembled InAs quantum dot
Authors: Kim Erik D. , Truex Katherine , Wu Yanwen , Amo A. , Xu Xiaodong , Steel D. G. , Bracker A. S. , Gammon D. , Sham L. J.
Published: September 2010

We demonstrate an experimental technique for the transient read-out of the optical transitions in a single negatively charged self-assembled InAs quantum dot (QD) using resonant picosecond optical pulses and control of the QD charge state. Observable phenomena include trion (negatively charged exciton) decay, Rabi oscillations between the electron and trion states and the precession of electron and heavy-hole spins about an externally applied dc magnetic field.
Longitudinal optical phonon assisted polariton laser
Authors: Maragkou M. , Grundy A. J. D. , Ostatnický T. , Lagoudakis P. G.
Published: September 2010

We demonstrate the role of longitudinal optical (LO)-phonon assisted polariton relaxation in reducing the stimulation threshold in strongly coupled microcavities. When the energy of the relaxation bottleneck is one LO-phonon above the ground polariton state, we observe a tenfold improvement of the polariton relaxation rate in the linear regime, and a twofold reduction in the threshold to the nonlinear polariton lasing regime.
Experiments on solar absorption using a greenhouse-effect gas in a thermal solar collector
Authors: Alami Abdul Hai M. B.
Published: September 2010

This paper investigates an augmentation to the thermal solar absorption of solar collectors by introducing a greenhouse gas between the glazing and the absorber part of the solar collector. Experiments are designed and conducted to compare the effect of adding the gas on the efficiency of the collector without that addition. The maximum temperature rise of the absorber, the time of heat retention before reaching room temperature, and the energy conversion efficiency in heating up water for domestic use were all studied.
Early development of cutaneous cancer revealed by intravital nonlinear optical microscopy
Authors: Wang Chun-Chin , Li Feng-Chieh , Lin Wei-Chou , Chen Yang-Fang , Chen Shean-Jen , Lin Sung-Jan , Dong Chen-Yuan
Published: September 2010

We performed intravital multiphoton microscopy to image and analyze normal and carcinogen treated skin tissues of nude mice in vivo. Using intravital images and the quantitative pixel to pixel ratiometric processing of multiphoton autofluorescence to second harmonic generation index (MAFSI), we can visualize the interaction between epithelial cells and extracellular matrix. We found that as the imaging depth increases, MAFSI has different distribution in normal and treated cutaneous specimens. Since the treated skin eventually became squamous cell carcinoma, our results show that the physiological changes to mouse skin en route to become cancer can be effectively tracked by multiphoton microscopy.
High emission current density, vertically aligned carbon nanotube mesh, field emitter array
Authors: Li Chi , Zhang Yan , Mann Mark , Hasko David , Lei Wei , Wang Baoping , Chu Daping , Pribat Didier. , Amaratunga Gehan A. J. , Milne William I.
Published: September 2010

A vertically aligned carbon nanotube mesh emitter array has been fabricated and tested, giving a current density of up to 1.5 A/cm2, and a threshold field of 1.5 V/μm for a current density 1 mA/cm2. Low temperature carbon nanotube growth is used to fabricate the carbon nanotube mesh emitter arrays significantly reducing the cost of the fabrication of large area electron emitters. This system exhibits ultralong lifetime.
Charge modulated reflectance topography for probing in-plane carrier distribution in pentacene field-effect transistors
Authors: Manaka Takaaki , Kawashima Satoshi , Iwamoto Mitsumasa
Published: September 2010

By using charge modulated reflectance (CMR) topography, we showed that the in-plane carrier distribution in pentacene field-effect transistors (FETs) can be directly probed under the device operation. Further, we showed that the observed CMR signal is attributed to a decrease in the electron population in pentacene highest occupied molecular orbital level, caused by hole injection. The signal profile along the FET channel strongly depends on the bias conditions. The carrier density decreases monotonously along the channel from the source to the drain in the saturated region; this decrease is interpreted by a simple model based on interfacial accumulated charge transportation.
Understorey fire propagation and tree mortality on adjacent areas to an Amazonian deforestation fire
Authors: Carvalho Jr J. A. , Gurgel Veras C. A. , Alvarado E. C. , Sandberg D. V. , Leite S. J. , Gielow R. , Rabelo E. R. C. , Santos J. C.
Published: September 2010

Fire characteristics in tropical ecosystems are poorly documented quantitatively in the literature. This paper describes an understorey fire propagating across the edges of a biomass burn of a cleared primary forest. The experiment was carried out in 2001 in the Amazon forest near Alta Floresta, state of Mato Grosso, Brazil, as part of biomass burning experiments conducted in the same area since 1997. The vegetation of a 200 × 200-m2 forested area was clear-cut in early June and burned in late August. The understorey fire that escaped from the main burn was monitored across the four sides of the land clearing area. Flame-front spread varied between 0.14 and 0.35 m min–1. Maximum flame height was about 30 cm and typical flame depth was 10 to 15 cm. Tree mortality was investigated in 2003 in four areas adjacent to the biomass burning experiment. A total of 210 trees were counted in the four areas, 29.5% were dead as a consequence of the understorey fire that had occurred 2 years before. This fire-caused mortality is evidence of the synergistic effect between slash burning, tree mortality and future fire vulnerability on the forest–land clearing interfaces.
First-principles study of CuAlS2 for p-type transparent conductive materials
Authors: Huang Dan , Tian Ren-Yu , Zhao Yu-Jun , Nie Jian-Jun , Cai Xin-Hua , Yao Chun-Mei
Published: September 2010

We have investigated the intrinsic defects, and Mg, Zn impurities in CuAlS2, as well as their induced carrier concentrations using the first-principles calculations. We find that p-type conductivity could be dominated by the intrinsic defects VCu, CuAl or the doping defects ZnAl, MgAl in different samples. Although vacancy Cu is an important acceptor in CuAlS2, a Cu-deficient sample is not the best for p-type conductivity due to the compensation from AlCu defects. In fact, our results indicate that Zn is the best choice for p-type doping for CuAlS2, in particular under Cu-rich and Al-poor condition, which is in line with the experimental results. The main difference in carrier concentration between theory and experiment is expected to have originated from the multiphase of the samples prepared in experiments, instead of a single crystal. We also find that there is no remarkable difference in the effective mass in samples dominated by different defects, such as CuAl, MgAl, ZnAl and Cu vacancy. The significant difference in the experimentally observed hole mobility may be dominated by their mean free time τ
p
.