Room Temperature Research Papers - Academia.edu (original) (raw)

We report on structural, magnetic, electrical, and thermodynamic properties of Gd-doped LaMnO3 single crystals for Gd doping levels 0 <= x <= 1. At room temperature, for all doping levels the orthorhombic O' phase is indicative for a strong Jahn-Teller distortion. All compositions are insulating. The magnetism of La$_{1-x}$Gd$_x$MnO$_3$ is dominated by the relatively strong Mn-Mn exchange. The weakening of the antiferromagnetic interactions due to the significant decrease f the Mn-O-Mn bond angles leads to the continuous suppression of the magnetic phase-transition temperatures into the antiferromagnetic low-temperature phase for increasing Gd doping. The magnetization can only be explained assuming canting of the manganese spins. The magnetic moments of Gd are weakly antiferromagnetically coupled within the sublattice and are antiferromagnetically coupled to the Mn moments. For intermediate concentrations compensation points are found, below which the spontaneous magnetization becomes negative. In pure GdMnO3 the Mn spins undergo a transition into a complex, probably incommensurate magnetic structure at 41.5 K, followed by a further ordering transition at 16-20 K revealing weak ferromagnetism due to canting and finally by the onset of magnetic order in the Gd sublattice at 6.5 K. At the lowest temperatures and low external fields both magnetic sublattices reveal a canted structure with antiparallel ferromagnetic components.

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- Physical sciences, CHEMICAL SCIENCES, Room Temperature, Single Crystal

The effects of aging on mechanical behavior of lead free solders have been examined by performing creep tests on four different SAC alloys (SAC105, SAC205, SAC305, SAC405) that were aged for various durations (0-4 months) at room temperature (25degC), and several elevated temperatures (75, 100, and 125 degC). Analogous tests were performed with 63Sn-37Pb eutectic solder samples for comparison purposes. Variations of the creep properties were observed and modeled as a function of aging time and aging temperature. In addition, the chosen selection of SAC alloys has allowed us to explore the effects of silver content on aging behavior.

- by Michael Bozack
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- Room Temperature, Elevated Temperature

Ethyl glucuronide (EtG) is a minor and direct metabolite of ethanol. EtG is incorporated into the growing hair allowing retrospective investigation of chronic alcohol abuse. In this study, we report the development and the validation of a method using gas chromatography–negative chemical ionization tandem mass spectrometry (GC–NCI-MS/MS) for the quantification of EtG in hair. EtG was extracted from about 30mg

- by Marc Augsburger
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- Earth Sciences, Analytical Chemistry, Forensic Medicine, Food Chemistry
- by PIERO BAGLIONI
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- Archaeology, Cultural Heritage, Soft Matter, Rheology

The effect of corrosive solutions on stress relaxation behavior of pure Mg and its alloys is studied. Pure magnesium shows a crucial corrosion stress relaxation in 3.5wt.% NaCl even at room temperature in comparison with tests in air. Die-cast Mg alloys AZ91D, AM50 and AS21 at room temperature show a relatively small stress decrease both in air and in different

- by Emmanuel Gutman
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- Stress relaxation, Magnesium, Dislocations, Grain Boundary

The present study investigates the possibility of the non-destructive prediction of the main quality indices of commercial eggs by calculating the ultrasound phase velocity within the egg material. The phase velocity of the ultrasound signal in the egg material was determined by analysing the recorded ultrasound signals using the Fast Fourier Transform. Three hundred commercial eggs (Boris Brown, 33 weeks age) from the first day of egg laying were purchased from a farm and divided in two groups. The first group was kept at the room temperature (22–25°C) and the second group was kept in a refrigerator (5°C). Every week, 25 eggs from both the room and the refrigerator were first submitted to the non-destructive ultrasound test at weekly basis at the room temperature. Immediately after testing, the air cell, the thick albumen heights, the Haugh unit and the yolk index of the eggs were also determined destructively for the comparison purposes. The results were analysed to find any possi...

- by kamal setarehdan
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- Agricultural Engineering, Materials Science, Ultrasound, Egg Laying
- by Gajanan Muley
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- Crystal Growth, Nonlinear Optics, FTIR spectroscopy, Second Harmonic Generation

We report ballistic magnetoresistance (BMR) values in magnetic nanocontacts for Ni, Co, and Fe. The samples range from atomic nanocontacts (smaller than 1nm cross-section) to stable electrodeposited nanocontacts (up to 30nm cross-section). The experiments are done at room temperature and up to 4kOe applied field. We obtain values of stable BMR up to 700%. By manipulating the resistance and the

- by François Flory
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- Engineering, Physics, Remote Sensing, Applied Physics

We report the preparation of hydroxyapatite in powdered form by aqueous reaction of calcium nitrate or hydroxide with phosphate ion at room temperature. With a slow maturation step of 48 h avoiding heat, the resulting products show large specific surface areas above 150 m2/g. The specific surface areas also depend on stirring speed with a maximum observed with gentle mixing. Ageing causes

- by Gilles Flamant
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- Engineering, Materials Science, Hydroxyapatite, Materials

Highly selective synthesis of diphenylmethane (DPM) was carried out by Friedal–Crafts benzylation of benzene using benzyl chloride (BC) as alkylating agent in the presence of a flow of nitrogen under liquid phase reaction conditions over novel mesoporous SO42−/Al-MCM-41 catalysts with different Si/Al ratios. For these reactions, the influences of various reaction parameters, such as different catalysts, reaction temperature, time, mmol

- by Prof. M. Selvaraj
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- Chemical Engineering, Chemistry, Heterogeneous Catalysis, Conversion
- by John Ruter
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- Olive Oil, Organic Fertilizer, Acid Soil, Room Temperature
- by Carlos Caceres
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- Light Metals, Case Study, Room Temperature, Chemical Composition
- by R. Mahmudi
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- Materials Design, Room Temperature, Solid Solution
- by Mark Zahniser and +1
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- Mechanical Engineering, Carbon Dioxide, Optical physics, Room Temperature

Pt nanoparticles were supported on Sb2O5.SnO2 (ATO), on carbon and on physical mixtures of ATO and carbon by an alcohol-reduction process using ethylene glycol as reducing agent. The obtained materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Their performance for ethanol oxidation was investigated at room temperature by chronoamperometry and in a direct ethanol fuel cell (DEFC) at 100 °C. Pt nanoparticles supported on a physical mixture of ATO and carbon showed a significant increase of performance for ethanol oxidation compared to Pt nanoparticles supported on ATO or on carbon.

- by Atos Silva
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- Engineering, Transmission Electron Microscopy, Fuel Cell, Hydrogen Energy
- by Dr. Keyur Patel
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- Inorganic Chemistry, Scanning Electron Microscopy, Nanotechnology, Zinc Oxide
- by Oscar Moreno
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- Engineering, Applied Physics, Crystal structure, Mathematical Sciences
- by Michele Dipalo and +1
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- Materials Engineering, Chemical Engineering, PHOTOELECTRON SPECTROSCOPY, X Rays
- by Sandeep Gaan
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- Engineering, III-V Semiconductors, Applied Physics, Molecular beam epitaxy

In this paper, we present preliminary results showing the response of glucose-sensitive hydrogels, confined in micro-pressure sensors, to the changes in environmental glucose concentration. The glucose concentrations were incrementally varied between 20 and 0mM in 0.15M PBS solution at 7.4 pH and bovine serum at 7.4 pH at room temperature and response of the sensor was recorded. The micro sensors demonstrate a response time of 10 minutes in both PBS and serum. Tissue response after 55 days of subcutaneous implantation of a EtO sterilized sensor in mice is presented. The preliminary analysis of the surrounding tissue shows inflammation which is believed not to interfere with the sensor performance.

- by Florian Solzbacher
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- Hydrogels, Transducers, Blood Glucose, Mice
- by Robert Short
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- Food Microbiology, Food Preservation, Multivariate Analysis, Humans
- by Shuehlin Yau
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- Engineering, Chemistry, Scanning tunneling microscopy, Physical sciences
- by Marek Maciejewski
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- Environmental Engineering, Chemical Engineering, Chemistry, Regeneration

Photoemission spectra taken at room temperature with high energy and angle resolution on Bi2Sr2CaCu2O8 single crystals reveal a band near EF with weak dispersion along lambdaX. It crosses EF at about 1/2 lambdaX and the occupied part becomes visible up to the Brillouin zone boundary in angle-resolved inverse photoemission spectra. Starting for T&gt;Tc with a clear Fermi edge, for T&lt;Tc

- by Recardo Manzke and +1
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- Materials Engineering, Physics, Condensed Matter Physics, Electronic Structure

The functional properties of fats are determined by the distribution pattern of fatty acid residues in their acylglycerols, which may be modified by ester interchange (transesterification). In the margarine industry, the time course of the transesterification of fat blends is monitored by assaying for the amount of the solid fraction at different temperatures (SFC-solid fat content) currently measured by nuclear magnetic resonance (NMR). The aim of this study was to evaluate the feasibility of near infrared spectroscopy (NIRS) to quantify ...

- by aurelizio alves
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- Chemistry, Analytical Chemistry, Nuclear Magnetic Resonance, Sample Preparation
- by Kenneth Weil
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- Engineering, Hydrogen Energy, Palladium, CHEMICAL SCIENCES
- by Demetrius C Levendis
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- Second Order, Room Temperature

Deep Inelastic Neutron Scattering provides a means of directly and accurately measuring the momentum distribution of protons in water, which is determined primarily by the protons ground state wavefunction. We find that in water confined on scales of 20A, this wave function responds to the details of the confinement, corresponds to a strongly anharmonic local potential, shows evidence in some cases of coherent delocalization in double wells, and involves changes in zero point kinetic energy of the protons from -40 to +120 meV difference from that of bulk water at room temperature. This behavior appears to be a generic feature of nanoscale confinement. It is exhibited here in 16A inner diameter carbon nanotubes, two different hydrated proton exchange membranes(PEMs), Nafion 1120 and Dow 858, and has been seen earlier in xerogel and 14A diameter carbon nanotubes. The proton conductivity in the PEM samples correlates with the degree of coherent delocalization of the proton.

- by Kenneth Mackenzie
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- Engineering, Dielectric Properties, CHEMICAL SCIENCES, Dielectric Loss

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyr...

- by ingrid falnoga
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- Liver, Solvent Extraction, Mercury, Animals
- by Alexei Gruverman
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- Atomic Force Microscopy, Multidisciplinary, Thin Film, Electron Transport
- by Mark Mann
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- Materials Engineering, Condensed Matter Physics, Carbon Nanotube, Nanotechnology

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, β-naphthol and urea or amides, in the presence of potassium dodecatungstocobaltate trihydrate [K5CoW12O40 · 3H2O, (1 mol%)] as a heterogeneous catalyst. The reactions were carried out in 1,2-dichloroethane at room temperature or under solvent-free media at elevated temperature. The present methodology offers several advantages such as excellent yields, simple procedure and the catalyst exhibited remarkable reusability.

- by Srini Kante
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- Chemical Engineering, Catalysis, Molecular, Reaction Time

In this study, hydrogen sensing properties of nanoporous Pd films based on Anodic Aluminium Oxide (AAO) templates grown on a silicon substrate have been investigated at various temperatures (25–100°C) and hydrogen concentrations (100–1000 ppm) to determine the temperature-sensitivity relationship. For this purpose, a hexagonally shaped AAO template of approximately 50 nm in diameter and 700 nm in length with 80 nm interpore distances was fabricated using two-step anodization of an Al film deposited on an n-type (100) oriented oxidized Si substrate. Then, the nanoporous surface of the AAO template was used as a substrate for supporting a nanoporous Pd film of an approximately thickness of 60 nm. The morphologies of the AAO template and Pd film coated on the AAO template were studied mainly by Scanning Electron Microscopy (SEM). Hydrogen sensing properties of the nanoporous Pd film were measured using a resistance transient method. It was found that the sensor response of the nanoporous Pd films on the AAO template was better than the traditional Pd thin film sensors, the sensitivity of the sensor was approximately 1.8% for 1000 ppm H2, and the detection limit was lower than 100 ppm at room temperature. The highest sensitivity was measured at room temperature.

- by Ivan Jerman
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- Engineering, Cell Cycle, Ionic Liquid, Physical sciences

A model to study the effect of the roughness at the poly-Si/SiO/sub 2/ interface in silicon inversion layers on the electron mobility is obtained. Screening of the resulting perturbation potential by the channel carriers is taken into account, considering Green's functions for metal-oxide-semiconductor (MOS) geometry, i.e. taking into account the finite thickness of the gate oxide. Mobility of electrons is evaluated at room temperature by the Monte Carlo method, taking into account the simultaneous contribution of phonon scattering, SiO/sub 2//Si interface roughness scattering, Coulomb scattering and remote surface roughness scattering. The contribution of excited subbands is considered. The resulting remote surface roughness scattering is shown to be strongly dependent on the oxide thickness, and degrades mobility curves at low inversion charge concentrations. The results obtained show that the effect of this scattering mechanism cannot be ignored when the oxide thickness is below 5 nm, (as in actual devices), even when (as is usual) very high doping concentrations are used.

- by Andres Godoy
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- Surface Roughness, Room Temperature, Monte Carlo Method
- by Angel G Rodriguez and +1
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- Engineering, Physical sciences, Infrared, Room Temperature
- by George Nakhla
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- Engineering, Kinetics, Biomass, Activated Sludge
- by D. Golodnitsky and +1
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- Materials Engineering, Condensed Matter Physics, Polymer Electrolyte, Ionic Conductivity
- by Kamal Dasgupta
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- Materials Engineering, Low Dose, Non crystalline solids, Dose rate
- by Marcello Baricco
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- Engineering, Hydrogen Energy, CHEMICAL SCIENCES, Phase Transformation
- by Kaspar Jansen
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- Finite element method, Finite Element, Coding, Numerical Method
- by Rahmat Adnan
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- Sterilization, High Temperature, Room Temperature, UV light
- by Afshin Falsafi
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- Materials Science, Viscoelasticity, Contact Mechanics, Contact angle