Miracle-dz/UniFAR-FTUs huggingface dataset:
The effect of interface-roughness and dislocation scattering on low temperature mobility of 2D electron gas in GaN/AlGaN

We present the results of our experimental and theoretical studies concerning the temperature dependence of electron mobility in a two-dimensional electron gas (2DEG) confined at the GaN/AlGaN interface. Experimental mobility of 2912 cm2 (V s)−1 at 4.2 K, remains almost constant up to lattice temperature TL = 150 K, it then decreases rapidly down to 1067 cm2 (V s)−1 at TL = 300 K. In order to compare the experimental results with the theory we use a simple analytical formula for low-field electron mobility based on 2D degenerate statistics for a 2DEG confined in a triangular well. We consider acoustic phonon, polar-optical phonon, dislocation and interface-roughness (IFR) scattering. The polar-optical phonon scattering is the dominant mechanism at high temperatures. At low temperatures, however, both the IFR and dislocation scattering explain, equally well, the observed mobility. In reality, however, a mixture of the two mechanisms together with the deformation potential and piezoelectric scattering will determine the low temperature mobility. The experimental results are discussed in the light of the calculations.
Materials for electrochemical capacitors: Theoretical and experimental constraints

Electrochemical capacitors, also called supercapacitors, are unique devices exhibiting 20 to 200 times greater capacitance than conventional capacitors. The large capacitance exhibited by these systems has been demonstrated to arise from a combination of the double-layer capacitance and pseudocapacitance associated with surface redox-type reactions. The purpose of this review is to survey the published data of available electrode materials possessing high specific double-layer or pseudocapacitance and examine their reported performance data in relation to their theoretical expectations.
Estudo do liquor de cupuaçu

O cupuacu (Theobroma grandiflorum Schum), que e um fruto amazonico, vem conquistando a cada ano mais espaco no mercado nacional e internacional com a comercializacao de sua polpa. Suas sementes, consideradas como subproduto, vem despertando interesse nao so no mundo cientifico como pelas industrias. Sabe-se que, a partir das sementes, pode-se obter produtos analogos aos oriundos das sementes de cacau, seguindo as mesmas etapas de processamento. Dentre esses produtos tem-se o liquor de cupuacu, semelhante ao liquor de cacau que e um dos ingredientes da formulacao do chocolate. Este trabalho teve como objetivo o estudo da obtencao e caracterizacao fisica, quimica e fisico-quimica do liquor de cupuacu. Obteve-se tres amostras de liquor de cupuacu, cada qual partindo de lotes diferentes de fermentacao. Foram avaliados a composicao centesimal e o comportamento reologico. O liquor de cupuacu apresentou alto teor de lipidios (63,93 a 66,51%) e alto valor calorico (677,35 a 691,17kcal/100g). O teor de proteinas variou de 8,95 a 10,31%. A viscosidade plastica de Casson diminuiu com o aumento de temperatura. A distribuicao do tamanho das particulas influenciou nas diferencas de viscosidades entre as amostras, havendo maior reducao de viscosidade plastica com o aumento da temperatura nas amostras que apresentaram maior diâmetro de particulas. A gordura de cupuacu apresentou comportamento newtoniano a 40oC.
EMULSION PROCESS OPTIMIZATION OF BRAZIL NUT OIL WITH CHEESE WHEY FOR ENCAPSULATION

Brazil nut is the cornerstone for sustainable economic exploitation of the Amazon region. Its nutritional importance relies specially on its lipid part, which represents around 70% of its nut, and it is constituted of mainly polyunsaturated fatty acids. Brazil nut oil is a rich source of the omega family, essential for the perfect functioning of the human body. Cheese whey is a valuable nutritive product with versatile functional properties. At the same time, cheese whey is one of the main sources of organic contamination in the dairy industry. The objective of this work was to optimize the emulsion process of Brazil nut oil and cheese whey for future encapsulation, in order to avoid degradation and maximize its use in the food industry. An experimental design formulation was applied to prepare emulsions containing Brazil nut oil, cheese whey, Arabic gum and lecithin where time of agitation, oil and whey concentrations were the independent variables. Emulsions were analyzed according to its stability under different storage conditions, microscopic structure and turbidity. Results indicate that emulsions stored at 4 °C showed the best stability indexes. Emulsion containing 17.5% w/w of oil and 30% w/w of cheese whey concentrations was the most stable. Results demonstrate that it is possible to emulsify Brazil nut oil with cheese whey in order to encapsulate.
Potential Aroma in Several Varieties of Spanish Grapes

Free and bound aroma compounds of eight Spanish grape cultivars (Albarino, Treixadura, Listan, Viura, Xarel.lo, Parellada, Garnacha, and Tempranillo) used in winemaking were studied. With a single-extraction procedure it was possible to provide information about the potential flavor of these varieties: bound aroma was determined directly by TFA glycoside analysis and indirectly by enzyme hydrolysis release of aglycon. An aroma data base of these varieties and a comparison between the grape flavor composition of each variety were established. Grape characteristics (sugars, acidity, polyphenols, juice yield), mainly due to climate and cultivar factors, were related with the aroma composition. Non-terpenyl compounds such as 2-phenylethanol and benzyl alcohol were the main glycosidically bound compounds of Spanish varieties. Direct determination of glycosides is better than hydrolysis of aglycon as an approach to the potential aroma of grapes. Keywords: Aroma; glycosides; Spanish grape cultivars; Albarino; ’.
Ultrasonic Assisted Fabrication of Nanocomposite Electrode Materials Au/C for Low-Voltage Electronics

Au/C nanocomposites have been obtained by the ultrasonic assisted reduction of HAuCl4 solutions, impregnated in carbon material pores, using NaBH4 as a reducing agent. It was established that conditions of nanocomposite (NC) synthesis exert an essential influence on the shape and size characteristics of Au filler and functional properties of NCs. Characterization of NCs by X-ray diffraction, small-angle X-ray scattering, and cyclic voltammetry methods has revealed that an increase in the NaBH4 concentration raises not only gold nanoparticle dispersion in composites but also an electrochemical capacitance of Au/C NC electrode materials. A higher specific capacitance (700 F/g) for the NC electrode (NC-5 wt%-Au/C-1) was observed at a scanning rate of 10 mV/s in the potential window from (−1)V to (+1)V.
Biostimulation strategies for fresh and chronically polluted marine environments with petroleum hydrocarbons

Stimulation of indigenous degraders with suitable nutrients can significantly enhance bioremediation rates of marine environments polluted with petroleum hydrocarbons. Biostimulation is emerging as the best strategy for combating oil spills following first response actions. This mini review is focused on the conditions under which biostimulation leads to increased effectiveness and strategies for successful biostimulation to fresh and chronically polluted sites are suggested. c � 2009 Society of Chemical Industry
Luminescence of Europium(III) and Terbium(III) Complexes Incorporated in Poly(Vinyl Pyrrolidone) Matrix

Lanthanide complexes of europium and terbium ions with hydrogen phthalate [Eu(Hphth)3 and Tb(Hphth)3, respectively, Hphth = hydrogen phthalate] were incorporated into poly(vinyl pyrrolidone) (PVP) matrix. Transmission electron microscopy (TEM) results showed that the lanthanide complexes, with a mean diameter about 8.0 nm, were dispersed homogeneously in the PVP matrix. The excitation of the Ln(Hphth)3-PVP system by UV light resulted in a ligand-to-metal energy transfer and the emission spectra of the complexes displayed characteristic luminescence of the central ions. PVP significantly affected the strength of the hypersensitive transitions (5D0 → 7F2 for Eu3+, and 5D4 → 7F5 for Tb3+) of the complexes. For the mixed complexes containing both Eu3+ and Tb3+ as central ions, the luminescent intensity was strongly dependent upon the ratio of the lanthanide ions. Trace amount of Eu3+ quenched the luminescence of the Tb3+, whereas the presence of Tb3+ enhanced the luminescence of the Eu3+, thus demonstrating a.
Die Bildung nichtoxidischer Sauerstoffphasen an Ru(0001)

The aim of the thesis presented here was the investigation of the formation of non oxidic oxygen phases on the Ru(0001) surface. Smooth and defect rich surfaces were exposed to high oxygen pressures ( up to 1 bar) at moderate temperatures (≤ 550 K). The characterisation was performed under UHV conditions using Thermal Desorption Spectroscopy (TDS), Scanning Photoemission Microscopy (SPEM), Thermal Energy Atomic Scattering (TEAS), Ultraviolett Photoelectron Spectroscopy (UPS) and Low Energy Electron Diffraction (LEED) as well as In situ by the In Situ X-Ray Photoelectron Spectroscopy (In Situ XPS). The application of this Low Temperature preparation procedure (LT) leads to an Oxygen uptake up to 3 MLE of ”subsurface” oxygen into a smooth Ru(0001) surface without the typical indications of oxidation (MLE: Monolayer Equivalent). The accumulation of oxygen beneath the surface starts immediatly after the completion of a full chemisorbed layer. Here, the local saturation of the adsorbed oxygen is the decisive step. Diffusion of oxygen directly through the chemisorbed layer only slightly contributes to the overall uptake. Oxygen is mostly accomodated in the vicinity of the surface via surface defects which has been shown on defect rich surfaces created by mild Ar sputtering. The maximum oxygen capacity is 10 Atoms/Defect. The uptake is thermally activated with an activation energy of 0.15 eV . The oxygen uptake causes a massive structural change of at least the top two ruthenium layers. Whereas the ruthenium atoms of the first layer are coordinated with up to four, those of the second layer are coordinated with up to two oxygen atoms. These binding condition are metastable and can be changed by annealing the surface. With reaching the desorption temperature two distinct desorption peaks are observed with TDS. For an accumulation of about 0.5 MLE of ”subsurface” oxygen the desorption proceeds exclusively at the characteristic temperature of the chemisorbed layer at 1040 K. With further increasing oxygen contents underneath the topmost ruthenium layer the bond of the chemisorbed oxygen is reduced leading to an additional desorption feature at a lower temperature of ∼ 950 K. The ”subsurface”phases formed that way can be considered as a precursor to the oxide formation. In an intermediate preparation range in between 550 and 600 K for very high oxygen exposures the formation of oxidic phases are observed whose spacial dimensions cannot be resolved with SPEM. The onset of oxide formation is characterized by the growth of RuO2(110) oxide domains in dependence of oxygen exposure and sample temperature. The areas in between the oxide domains do not spectroscopically resemble either the chemisorbed layer or the oxide. In fact they show the features of a strongly distorted and oxygen enriched surface.
Effect of Ozone Pretreatment on Biodegradability Enhancement and Biogas Generation Potential From Biomethanated Distillery Effluent

The study evaluates the effect of ozone pretreatment on biodegradability enhancement of biomethanated distillery effluent. Results revealed that ozone pretreatment led to biodegradability index (BI = BOD/COD) enhancement up to 0.58 along with COD, color and toxicity reduction of up to 33%, 25% and 40%, respectively. Anaerobic digestion of pretreated effluent resulted in favorable biogas generation with methane content, yield and COD reduction of up to 62%, 39 mL/g COD and 57%, respectively. Kinetics of biogas generation determined by modified Gompertz model indicated methane production potential and production rate of 48.08 mL/g COD and 8.085 mL/g COD.day respectively under optimal conditions.
Thermal Properties of the Water Confined within Nanopores of Silica MCM‐41

Adiabatic calorimetry was carried out of the water confined within the pores of silica MCM‐41 with diameters of 1.2, 1.6, and 1.8 nm. Glass transitions were found at Tg = 115 and 165 K in the 1.2 nm case, 117, 165, and 205 K in the 1.6 nm, and 118 and 210 K in the 1.8 nm, respectively. The transition at Tg = 115–118 K was interpreted as caused by the freezing of the rearrangement of the water molecules located on the pore wall and interacting with silanol groups, and those at Tg = 165 and 205–210 K of the water molecules located in the center of the pores. It was noticed that the Tg increased discretely with increasing the pore diameter from 115 to 165 to 210 K. This indicates that the Tg and therefore the activation energy for the rearrangement are strongly connected with the development of the hydrogen‐bond network and furthermore the number of the hydrogen bonds formed by each water molecule. It was suggested that the bulk water undergoes the glass transition at Tg = 210 K rather than at 136 and 165 K .
Superconductivity on the threshold of magnetism in CePd2Si2 and CeIn3

The magnetic ordering temperature of some rare-earth-based heavy-fermion compounds is strongly pressure dependent and can be completely suppressed at a critical pressure, pc, making way for novel correlated electron states close to this quantum critical point. We have studied the clean heavy-fermion antiferromagnets CePd2Si2 and CeIn3 in a series of resistivity measurements at high pressures up to 3.2 GPa and down to temperatures in the mK region. In both materials, superconductivity appears in a small window of a few tenths of a GPa on either side of pc. We present detailed measurements of the superconducting and magnetic temperature-pressure phase diagram, which indicate that superconductivity in these materials is enhanced, rather than suppressed, by the closeness to magnetic order.
Etude structurale et fonctionnelle par RMN d'une chaperonine de 1 MDa en action

Les chaperonines sont des chaperonnes moleculaires indispensables pour le repliement de certaines proteines dans les cellules. La taille et la complexite de ces machineries biologiques rendent complexes l'etude de leurs proprietes structurales et fonctionnelles. La spectroscopie RMN permet de suivre des changements structuraux et dynamiques en temps reel avec une resolution atomique. Cependant, l'etude par RMN de proteines ou de complexes de haut poids moleculaires a ete un challenge pendant de nombreuses annees. Dans la premiere partie de cette these, il a ete montre que la combinaison de marquage specifique des groupements methyles, d'experiences RMN optimisees et de microscopie electronique peut etre utilisee pour suivre differents etats du cycle fonctionnel d'une chaperonine de 1 MDa. Pour etudier ce mecanisme, la chaperonine native a ete reconstituee avec un marquage des groupements methyles des methionines et valines. Les residus methionines ont pu etre utilises comme des sondes pour identifier les spectres RMN correspondant aux etats intermediaires et aux especes actives du cycle fonctionnel. Grâce a ces sondes il a ete possible de suivre en temps reel les rearrangements structuraux correspondant aux differentes conformations de la chaperonine durant son cycle fonctionnel. La seconde partie traite de la caracterisation de l'interaction de la chaperonine avec une proteine cliente depliee. L'observation de la stabilisation de l'etat deplie de la proteine par la chaperonine a permis de mettre en evidence une activite de "holdase" de la chaperonine. En utilisant une combinaison astucieuse de differents marquages de groupements methyles et d'experiences RMN optimises pour des assemblages de haut poids moleculaire, il a ete possible d'observer le repliement de cette proteine par la chaperonine et les effets de la presence d'une proteine depliee sur le cycle fonctionnel de la chaperonine en action.
Blueing, bleaching, and blinking of single CdSe/ZnS quantum dots

Room temperature time-resolved luminescence measurements on single CdSe/ZnS quantum dots (QDs) are presented.Luminescence spectra were recorded over time periods of up to 30 min with a time resolution down to 6 ms.A clear 30 ± 40 nm blue shift in the emission wavelength is observed for QDs in ambient air, before the luminescence stops after about 2 ± 3 min due to photobleaching. The blue shift is absent in a nitrogen atmosphere and photobleaching occurs after much longer times, 10 ± 15 min.These observations are explained by photoinduced oxidation.During illumination in the presence of oxygen the surface of CdSe is oxidized, which effectively results in shrinkage of the CdSe core diameter by almost 1 nm and, consequently, in a blue shift.This also influences the blinking behavior.The faster fading of the luminescence in air suggests that photoinduced oxidation results in the formation of nonradiative recombination centers at the CdSe/ CdSeOx interface.In a nitrogen atmosphere photoinduced oxidation is prevented by the absence of oxygen.A surprising observation is a higher initial light output for CdSe/ZnS QDs in air.We explain this higher light output by a fast reduction of the lifetime of the long-lived defect states of CdSe/ZnS QDs by oxygen.
Evolution de la pollution apportée par les baigneurs dans les eaux de piscines sous l'action du chlore.

Le suivi de l'evolution, sur plusieurs cycles journaliers, du carbone organique total (C.O.T.), de l'azote organique (NK ) et de quelques parametres specifiques dans l'eau des bassins de piscines, nous a permis de determiner les flux de pollution apportee par les baigneurs, et amenes a definir une unite de frequentation : l'equivalent-baigneur.Le flux specifique de COT emis par equivalent baigneur, est de 0,55 g en l'absence ou lorsque la chloration de l'eau est faible. Il s'eleve a 1 g lorsque la teneur en chlore est regulierement superieure a 1 mg/l. Par contre, le flux specifique d'azote organique reste stable et voisin de 0,85 g/eq.baigneur. Cette pollution organique est essentiellement due a l'uree (env. 60 % du NK ), a la creatinine et, dans une moindre mesure, aux acides amines. Ces molecules presentent une tres grande reactivite vis a vis du chlore. Les composes N-chloro formes se degradent plus ou moins lentement, selon des reactions complexes, pour donner des chloramines minerales, notamment du NCl3 facilement transferable dans l'atmosphere.La demande en chlore, apres une heure, appelee "demande specifique", est de 7,0 ± 0,5 g de Cl2 /eq.baigneur. Pour tenir compte des reactions les plus lentes, on a egalement determine la demande en chlore apres 24 h. Sa moyenne, indicatrice de la demande totale, s'eleve a 10,5 ± 0,5 g de Cl2 /eq.baigneur. Enfin, l'etude de l'evolution des teneurs en chlore combine, dans plusieurs piscines, a montre que ce parametre est tres dependant du volume d'eau disponible par baigneur.
Effect of process management on the emission of organosulfur compounds and gaseous antecedents from composting processes

Pilot-scale studies were performed to assess the effects of aeration rate and initial moisture content on the emissions of odorous organosulfur compounds and nonodorous gaseous antecedents from synthetic food waste (SFW) and biosolids composting processes. In the SFW studies peak organosulfur emissions occurred at an airflow rate of 0.16 L/min-kg VS. Emission rates (mol/time) and total aerobic biological activity (cumulative mass of O 2 consumed) were lower at 0.07 L/min-kg VS, possibly because the slightly higher temperatures encountered at this rate suppressed microbial activity. Emission rates were progressively lower at 0.32 and 0.65 L/min-kg VS, likely because of higher oxygen levels. As moisture content increased from 45 to 55% (H 2 O/g wet weight), peak emission rates generally increased. In the biosolids studies organosulfur emissions decreased as aeration rate increased. In both the SFW and biosolids studies CO was emitted prior to the detection of organosulfur compounds. Additionally, average correlation coefficients relating the emission rate of CO with the emission rate of organosulfur odors were 0.67 for the SFW trials and 0.75 for the biosolids trials. These results suggest that CO may be a good antecedent compound for the early warning of odors from composting processes.
Hierarchical vanadium oxide microspheres forming from hyperbranched nanoribbons as remarkably high performance electrode materials for supercapacitors

Novel hierarchical vanadium oxide microspheres forming from hyperbranched growth of nanoribbons have been successfully synthesized by a solvothermal method. The as-prepared hierarchical microspheres have a diameter of ∼5 μm, in which ∼400 nm long nanoribbons grow as hyperbranches on the clustering nanobelt backbones. These hierarchical microspheres contain 86.2 mass% V6O13 with metallic conductivity and 13.8 mass% VO2. Investigation of the growth mechanism indicates that EG plays an important role in the formation of hierarchical microspheres by regulating the solvent polarity and vanadium valences. The hierarchical microspheres exhibit a specific capacitance as remarkably high as 456 F g−1, with a corresponding volumetric specific capacitance of 3.09 F cm−3, at 0.6 A g−1 in the potential range of 0 to 1.2 V. The maximal energy density and power density achieved are up to 22.8 W h kg−1 (0.16 mW h cm−3) and 1.2 kW kg−1 (8.14 mW cm−3). The high performance of hierarchical vanadium oxide microspheres can be ascribed to the high specific surface area and large amount of mesopores provided by the hierarchical architecture, and the high conductivity and density of V6O13 in a high content in the hierarchical microspheres. This work has provided a new strategy to increase the specific capacitance of transition-metal oxides as electrode materials for the next-generation supercapacitors.
Selective-Area Atomic Layer Deposition Using Poly(methyl methacrylate) Films as Mask Layers

Selective-area atomic layer deposition (ALD) was achieved using poly(methyl methacrylate) (PMMA) films as growth inhibiting mask layers. The PMMA films were prepared from PMMA−toluene solution by spin-coating and patterned by UV lithography through a mechanical mask. The patterned PMMA films were tested in several ALD processes, both noble metals and oxides. The tested noble metal processes were iridium, platinum, and ruthenium, and the oxide processes were Al2O3 and TiO2. Al2O3 was deposited using AlCl3 and H2O and trimethylaluminum (TMA) and H2O. TiO2 was deposited using Ti(OMe)4 and H2O. The growth temperatures were 250−350 °C.
An improved method for measuring soil N2O fluxes using a quantum cascade laser with a dynamic chamber

A dynamic chamber method was developed to measure fluxes of N2O from soils with greater accuracy than previously possible, through the use of a quantum cascade laser (QCL). The dynamic method was compared with the conventional static chamber method, where samples are analysed subsequently on a gas chromatograph. Results suggest that the dynamic method is capable of measuring soil N2O fluxes with an uncertainty of typically less than 1–2 µg N2O‐N m−2 hour−1 (0.24–0.48 g N2O‐N ha−1 day−1), much less than the conventional static chamber method, because of the greater precision and temporal resolution of the QCL. The continuous record of N2O and CO2 concentration at 1 Hz during chamber closure provides an insight into the effects that enclosure time and the use of different regression methods may introduce when employed with static chamber systems similar in design. Results suggest that long enclosure times can contribute significantly to uncertainty in chamber flux measurements. Non‐linear models are less influenced by effects of long enclosure time, but even these do not always adequately describe the observed concentrations when enclosure time exceeds 10 minutes, especially with large fluxes.