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

The application of a new class of organogels as cleaning tools for painted surfaces is described. It combines some of the most attractive features of cleaning liquids and normal gels while diminishing the deleterious characteristics of both. Thus, the 'latent' gellant, polyethyleneimine (PEI), reacts with CO 2 at room temperature in solutions of several organic liquids to produce an ammonium carbamate form (PEICO 2 ). This charged species organizes itself into 3D polymer networks which immobilize the liquids as gels. The properties of the original solution (i.e. a free-flowing liquid) are re-established immediately after addition of a small amount of a weak acid which displaces the CO 2 molecules and makes the PEI chains positively charged. The visual changes are substantiated by rheological analyses. Results from analytical tests to determine the utility of these gels as cleaning tools for painted surfaces of historical and artistic interest, have been obtained from contact angle and FTIR measurements as well as visual comparisons of the surfaces before and after application of the gels. The analyses indicate that the PEICO 2 -based organogels were very effective in removing different surface patinas from painted supports. A surface layer of dammar was completely removed from a test canvas with oil paint, an aged painting from the XIX century, and a XV century oil-on-wood panel attributed to Mariotto di Cristoforo. Finally, a surface acrylic polymeric resin (used in a restoration performed during the 1960s) was also successfully removed from Renaissance wall paintings decorating the Santa Maria della Scala Sacristy in Siena, Italy. The isothermally rheoreversible gel approach described in this work represents a new, highly versatile, and very efficient method for removing aged surface patinas from works of art.

- by PIERO BAGLIONI
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- Archaeology, Cultural Heritage, Soft Matter, Rheology

Linear poly(dimethylsi1oxane diol) of about 650 D.P. was synthesized by hydrolytic condensation of dimethyldichlorosilane in a saturated solution of sodium chloride. The polymer was then compounded with various fillers, Cab-O-Sil, Dicalite, and titanium dioxide, and cured at room temperature in the presence of tin salt and tri-or tetrafunctional s h e . The tensile strength and elongation of the unfilled rubber were found to be 0.8 kg/cm2 and 320%, respectively. However, Dicalite White (100 phr)-reinforced elastomer showed a tensile strength of 40 kg/cm2. Crosslink density was determined from the swelling studies. Thermal aging at 150,200, and 25OOC was also studied.

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

Single crystals of L-Tartaric acid (C 4 H 6 O 6), an organic nonlinear optical (NLO) material, have been grown by hanging seed solution and submerged seed solution techniques at room temperature. The crystal system has been confirmed from the single crystal X-ray diffraction analysis. The crystalline perfection was evaluated using high-resolution X-ray diffractometry (HRXRD). From this analysis, it was found that the quality of the crystal is quite good. The functional groups were identified using FTIR spectroscopy. UV-vis-NIR spectrum showed the absence of absorption in the wavelength region of 220-900 nm. The second harmonic generation efficiency is 89% compared to that of standard potassium dihydrogen phosphate (KDP). The laser damage threshold value is much higher than that of KDP and closer to that of b-barium borate.

- 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

We report the detection of 100 ppm of butane in superatmospheric N 2 or air with an m-lines setup. The sensing elements are ZnO-nanostructured coatings prepared by pulsed laser deposition. The deposition technique was optimized to obtain highly transparent films of 1 cm 2 in area and several hundreds nanometer thick. ZnO structures preserve gas sensitivity even when deposited at room temperature. Refractive index variations down to 0.005 were detected and typical variations of about 20% were induced during ZnO film-butane contact.

- 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

Teaoil Camellia (Camellia oleifera Abel.) is a promising horticultural crop that has been cultivated for various purposes in China for more than 1000 years. It is a small tree, which grows naturally from latitudes of 18° to 34° North and in acidic soils where January mean temperatures do not drop below 2°C. As cooking oil, it compares favorably with olive oil, stores well at room temperature, and has a high smoke temperature. Teaoil is also used in the manufacture of soap, margarine, hair oil, lubricants, paint, rustproof oil and other compounds with a high-molecular weight as well as in cosmetology and dermopharmacy. Extracts from the residues of teaoil processing have been used in livestock feeds, pesticides and fertilizers. The use of tea oil products in controlling rice blast and wheat rust also suggests potential for the development of new biological-based pesticides from this plant. Although edible tea oil production covers about 40,000 km 2 in China, other countries know little about this species, only planting it as an ornamental plant. To share this valued crop to the world, selecting promising clones for targeted habitats is the key to success. Cloning propagation using hypocotyl grafting is recommended. Management practices, such as preparing planting sites with organic fertilizer, controlling weeds, thinning, pruning, alternating harvest time, improving harvest techniques, etc., could significantly increase the economic return for C. oleifera plantations. Further studies on the genetic improvement of tea oil will improve its popularity around the world.

- by John Ruter
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- Olive Oil, Organic Fertilizer, Acid Soil, Room Temperature

The possibility of developing an analytical quality index chart for applications above room temperature valid for dierent alloys is explored. The testing temperature and the chemical composition of the material are incorporated into the analysis through their respective eects on the material's strain hardening rate and yield strength. The resulting quality index chart has been used to compare the performance at room temperature, 100°C and 200°C of 16 experimental high-pressure die-cast aluminium alloys in terms of quality index, yield strength and tensile ductility. The best performance at 200°C is observed in alloys with high content of Mg or Cu and Mg and, depending on the Fe and Si content, Mn or Sr. The limitations of the approach are discussed.

- by Carlos Caceres
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- Light Metals, Case Study, Room Temperature, Chemical Composition

Creep behavior of Sn-9%Zn and Sn-8%Zn-3%Bi solders together with Sn-37% Pb, as the material for comparison, was studied by indentation tests at room-temperature (T > 0.6T m ) in order to evaluate the correspondence of the creep results obtained by different methods of analysis, and to evaluate the effect of Bi on the creep response of the eutectic Sn-9%Zn alloy. Stress exponent values determined through these methods were in good agreement. The better creep resistance of the ternary alloy is attributed to solid solutioning effect and precipitation of Bi in the Sn matrix. Both tin-based alloys showed creep resistances higher than that of the Sn-37% Pb alloy.

- 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

Nanocrystalline zinc oxide-thin films have drawn the attention of researchers due to its attractive properties like transparency in visible region, abundance in nature and gas sensitivity. Nanostructured Zinc oxide (ZnO) thin films were grown on silicon, alumina and glass substrates at various substrate temperatures using a 6 kW electron beam evaporation technique. The effects of film thickness, growth temperature and substrate on the crystallinity of deposited ZnO films were investigated using X-ray diffraction, scanning electron microscopy, optical absorption and photoluminescence studies. Our studies show that good quality films are obtained for silicon substrate for a growth temperature of 2508 8 8 8 8C. Film thickness plays an important role on the evolution of the nanostructures. SEM studies combined with XRD analysis reveal that ultrathin nanorods are grown with (002), (101) and (102) orientations. All the ZnO films show room temperature photoluminescence emission bands at 394 nm and 468 nm. Optical absorption studies show strong absorption at 377 nm. Details of the structure and optical properties correlation will be presented and potential of a simple technique such as e-beam deposition to grown ZnO nanostructures suitable for optoelectronic application will be assessed.

- by Dr. Keyur Patel
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- Inorganic Chemistry, Scanning Electron Microscopy, Nanotechnology, Zinc Oxide

We prepared SiO 2 @Ag core-shell nanospheres: silver nanoparticles ($4 ± 2 nm in diameter) coated silica nanospheres ($50 ± 10 nm in diameter). The preparation route is a modification of the Stöber method, and involves the preparation of homogeneous silica spheres at room temperature, combined with the deposition of silver nanoparticles from Ag + in solution, by using water/ethanol mixtures, tetraethylorthosilicate as Si source and silver nitrate as Ag source in a single-pot wet chemical route without an added coupling agent or surface modification, which leads to the formation of core@shell homogeneous nanospheres. We present the preparation and characterization of the SiO 2 @Ag core-shell nanospheres and also of bare silica spheres in the absence of silver, and propose a reaction mechanism for the formation of the core-shell structure.

Cadmium sulfide thin films were prepared by chemical bath on glass substrates at 80°C. CdS was Er-doped during the growth process by adding water-diluted Er͑NO 3 ͒ 3 3·H 2 O to the CdS aqueous growing solution. The relative volume of the doping solution was varied in order to obtain different doping levels. The crystalline structure of CdS:Er films was cubic zinc blende for all the doped layers prepared. The ͑111͒ interplanar distance has an irregular variation with the Er doping level. Consequently, the band gap energy ͑E g ͒ firstly increases and afterward diminishes becoming, at last, approximately constant at around E g = 2.37 eV. For higher doping levels, in the as-grown films, dark electrical conductivity ͑͒ values reach 1.8ϫ 10 −2 ⍀ −1 cm −1 at room temperature. The logarithm of vs 1 / kT plot, where k is Boltzmann's constant and T the absolute temperature, indicates an effective doping of CdS as a result of the Er introduction into the lattice of the material. Hall effect measurements reveal a n-type doping with 2.8ϫ 10 19 cm −3 as maximum carrier density.

- by Oscar Moreno
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- Engineering, Applied Physics, Crystal structure, Mathematical Sciences

The exposure of H-terminated nanocrystalline diamond (NCD) to ultraviolet (UV) light in air and at room temperature modifies the features of the diamond surface, in terms of wettability, electrical conductivity and chemical reactivity. This allows the development of a soft, dry and non invasive method to tailor the surface properties for the development of new chem-or bio-sensors.

- by Michele Dipalo and +1
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- Materials Engineering, Chemical Engineering, PHOTOELECTRON SPECTROSCOPY, X Rays

InAs/GaAs quantum dot heterostructures grown by molecular-beam epitaxy are studied using cross-sectional scanning tunneling microscopy and spectroscopy. The images reveal individual InAs quantum dots (QDs) having a lens shape with maximum base diameter of 10.5 nm and height of 2.9 nm. Analysis of strain relaxation of the QDs reveals an indium composition varying from 65% at the base of the QD, to 95% at its center, and back to 65% at its apex. Room-temperature tunneling spectra acquired 3-4 nm from the center of a dot show a peak located in the upper part of the GaAs bandgap originating from the lowest electron confined state of the QD, along with a tail in the conductance extending out from the valence band and originating from QD hole states. A computational method is developed for simulating the tunneling spectra using effectivemass bands treated in an envelope-function approximation. By comparison of the computations to low-current spectra, the energy of the lowest electron and highest hole QD states are determined. These energies are found to be in reasonably good agreement both with optical measurements and prior theoretical predictions of Wang et al. [Phys. Rev. B 59, 5678 (1999)].

- 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

Increasing concern regarding potential pathogens in infant formulas led to this evaluation of the influence of procedural and environmental factors on infant formula contamination. In two phases of study, a total of 526 formula samples were analyzed for contamination. In Phase 1, conducted from October 2001 through May 2002, nursing staff prepared formulas in the neonatal intensive care unit at bedside; in Phase 2, conducted from February 2006 through June 2006, dietetic technicians prepared formulas in a centralized feeding preparation room. Two types of formula, ready-to-feed and powder, were sampled. Each sample was divided into two portions; the first was cultured immediately, and the second after 8 hours at room temperature. Multivariate binary logistic regression models were tested to identify the major factors contributing to contamination. Results showed formulas prepared at bedside were 24 times more likely to show contamination than those prepared in a central location (PϽ0.001) and that powdered formulas were 14 times more likely to be contaminated than ready-to-feed formulas (PϽ0.001). In addition, samples that had been warmed (PϽ0.050) and those that were either milk-based or casein hydrolysate (PϽ0.001) were more likely to be contaminated. This study suggests that centralized feeding preparation results in a significant decrease in prevalence of microbial growth. Because contamination risk increases significantly with the use of powdered formulas, sterile liquid formulas should be considered when possible to minimize risk of microbial exposure in the neonatal intensive care unit population.

- by Robert Short
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- Food Microbiology, Food Preservation, Multivariate Analysis, Confidence intervals

In situ scanning tunneling microscopy (STM) and reflection high energy electron diffraction (RHEED) were used to characterize mercury film electrodeposited onto a Pt(1 1 1) electrode at room temperature. Depending on the amount of Hg deposit, two different growth modes were observed. At low Hg coverage, crystalline (0 0 0 1)Hg adlayer accompanied by 30 •-rotated (1 1 1)-Pt patches was found on Pt(1 1 1). Deposition of multilayer Hg resulted in layered PtHg 2 and PtHg 4 amalgams, which grew epitaxially by aligning their (2 0 1) and (11 0) planes, respectively, parallel to the Pt(1 1 1) substrate. The preference of these epitaxial relationships for the electrochemically formed Pt-Hg intermetallic compounds on Pt(1 1 1) could result from minimization of the surface energy.

- by Shuehlin Yau
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- Engineering, Chemistry, Scanning tunneling microscopy, Physical sciences

The formation and stability of BaAl 2 O 4 and BaCeO 3 in Pt-Ba/Al 2 O 3 and Pt-Ba/CeO 2 based NO x storage-reduction (NSR) catalyst has been investigated using kinetic measurements, X-ray diffraction, thermal analysis and X-ray absorption spectroscopy. In as-prepared state, the Ba-component in the NSR catalysts was made up of amorphous BaO and BaCO 3. The formation of BaAl 2 O 4 started above 850°C, whereas the formation of BaCeO 3 was already observed at 800°C and was faster than that of BaAl 2 O 4. The stability of BaAl 2 O 4 and BaCeO 3 in various liquid and gaseous atmospheres was different. BaAl 2 O 4 was rapidly hydrated at room temperature in the presence of water and transformed to Ba(NO 3) 2 and γ-alumina in the presence of HNO 3 , whereas BaCeO 3 was decomposed to much lower extent under these conditions. Interestingly, BaCeO 3 was transformed to Ba(NO 3) 2 /CeO 2 in the presence of NO 2 /H 2 O at 300-500 °C. Also the presence of CO 2 led to decomposition of barium cerate, which has important consequences for the catalyst ageing under NO x-storage conditions and can be exploited for regeneration of thermally aged NSR-catalysts.

- 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

The AgeCuO x system is being investigated as potential filler metals for use in air brazing high temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high temperature joint strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary AgeCuO x , and 15PdeAgeCuO. It was found that while the binary AgeCuO x system exhibits stronger room temperature strength than the 15Pd system the strength is reduced to values equivalent of the 15Pd system at 800 C. The 15Pd system exhibits a lower ambient temperature strength that is retained at 800 C. In both systems the failure mechanism at high temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower temperatures to cause fracture of the YSZ substrate.

- 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, Gas Chromatography

Stable and switchable polarization of ferroelectric materials opens a possibility to electrically control their functional behavior. A particularly promising approach is to employ ferroelectric tunnel junctions where the polarization reversal in a ferroelectric barrier changes the tunneling current across the junction. Here, we demonstrate the reproducible tunneling electroresistance effect using a combination of Piezoresponse Force Microscopy (PFM) and Conducting Atomic Force Microscopy (C-AFM) techniques on nanometer-thick epitaxial BaTiO 3 single crystal thin films on SrRuO 3 bottom electrodes. Correlation between ferroelectric and electronic transport properties is established by the direct nanoscale visualization and control of polarization and tunneling current in BaTiO 3 films. The obtained results show a change in resistance by about two orders of magnitude upon polarization reversal on a lateral scale of 20 nm at room temperature.

- by Alexei Gruverman
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- Atomic Force Microscopy, Multidisciplinary, Thin Film, Electron Transport

Carbon nanotubes (CNTs) are a unique form of carbon filament/fiber in which the graphene walls roll up to form tubes. They can exhibit either metallic-like or semiconductor-like properties. With the graphene walls parallel to the filament axis, nanotubes (single wall metallic-type or multi-wall) exhibit high electrical conductivity at room temperature. This high electrical conductivity allied to their remarkable thermal stability has made CNTs one of the most intensely studied material systems for field emission (FE) applications. In this paper we will describe the growth of multiwall CNTs and their application in a range of field emission based systems including their use in SEM sources, emitters for use in microwave amplifiers and as emitters in field emission based displays (FEDs).

- 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.

The main objective of this study was to broaden the assortment of I À /I 3 À redox ionic liquids using polyhedral oligomeric silsesquioxanes (POSS) acting as nanobuilding blocks for the construction of functionalized 1,3-alkylimidazolium... more

- 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

The optical energy gap of Ge 1−x Sn x alloys ͑x ഛ 0.14͒ grown on Ge substrates has been determined by performing transmittance measurements at 4 K using a fast fourier transform infrared interferometer. The direct energy gap transitions in Ge 1−x Sn x alloys behave following a nonlinear dependence on the Sn concentration, expressed by a quadratic equation, with a so called bowing parameter b 0 that describes the deviation from a simple linear dependence. Our observations resulted in b 0 RT = 2.30± 0.10 eV and b 0 4 K = 2.84± 0.15 eV, at room temperature and 4 K, respectively. The validity of our fit is limited for Sn concentrations lower than 15%.

- by Angel G Rodriguez and +1
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- Engineering, Physical sciences, Infrared, Room Temperature

In this work, batch activated sludge studies were investigated for the treatment of raw pet food wastewater characterized by oil and grease concentrations of 50,000-66,000 mg/L, COD and BOD concentrations of 100,000 and 80,000 mg/L, respectively, as well as effluent from an existing anaerobic digester treating the aforementioned wastewater. A pre-treatment process, dissolved air flotation (DAF) achieved 97-99% reduction in O&G to about 400-800 mg/L, which is still atypically high for AS. The batch studies were conducted using a 4-L bioreactor at room temperature (21 • C) under different conditions. The experimental results showed for the DAF pretreated effluent, 92% COD removal efficiency can be achieved by using conventional activated sludge system at a 5 days contact time and applied initial soluble COD to biomass ratio of 1.17 mg COD/mg VSS. Similarly for the digester effluent at average oil and grease concentrations of 13,500 mg/L, activated sludge affected 63.7-76.2% soluble COD removal at 5 days. The results also showed that all kinetic data best conformed to the zero order biodegradation model with a low biomass specific maximum substrate utilization rate of 0.168 mg COD/mg VSS day reflecting the slow biodegradability of the wastewater even after 99% removal of oil and grease.

- by George Nakhla
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- Engineering, Kinetics, Biomass, Activated Sludge

Ionic conductivity, which is the most important polymer electrolyte (PE) property, is considered to be higher in the totally amorphous matrix, and ion transport is assumed to be mediated primarily by the motion of polymer segments. Despite this conventional wisdom, we suggest that fast ion transport occurs preferentially along the PEO helical axis, at least in the crystalline phase. In this work, we have studied the effect of hot and room-temperature stretching on the structural properties, ion -polymer interactions and ionic conductivity in dilute and concentrated LiI:P(EO) n (3 V n V 100) PEs. SEM and XRD data show evidence of the formation of a more oriented polymer-electrolyte structure. Significant changes in the FTIR spectra of the diluted LiI:P(EO) n electrolytes are found for the skeletal vibration mode of the C -O -C groups. The effect of stretching on the FTIR spectra of concentrated PEs was found to be less pronounced than that of the dilute PEs. The stretching process was found to influence the conductivity in the direction of the force more strongly than does an increase in temperature. D

- by D. Golodnitsky and +1
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- Materials Engineering, Condensed Matter Physics, Polymer Electrolyte, Ionic Conductivity

The radiation response behaviour of high phosphorous doped step index multimode (SIMM) fibers of different P 2 O 5 concentrations and core diameters has been investigated in comparison with Ge doped SIMM fiber at different transmission wavelengths under 60 Co gamma irradiation with variation of dose rates from 1Rad/hr to 100Rad/hr. Radiation induced absorption curves of P doped fibres show two broad absorption peaks in the wavelength ranges 400-420nm & 500-560nm which arise due to phosphorous oxygen hole center defect. It has been observed that at 540nm & 560nm transmission wavelengths sensitivity shows strong dose rate dependence compared to that at 502nm wavelength but does not show any saturation behaviour. This reveals that P related defects do not anneal at room temperature and yield permanent change. The radiation sensitivity decreases with increasing transmission wavelengths from 502nm to 560nm with very low fading behaviour. The fiber containing 16mol% P 2O 5 with coreclad dimension of 42:125 micron has an excellent linear radiation response behaviour with sensitivity a round 1.0dB/m/100Rad at 502nm wavelength as well as very low recovery and dose rate independence. This enables its practical application in fiber optics personal dosimeter for measurement of low dose gamma radiation.

- by Kamal Dasgupta
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- Materials Engineering, Low Dose, Non crystalline solids, Dose rate

Ab initio calculations Calphad Thermal decomposition a b s t r a c t

- by Marcello Baricco
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- Engineering, Hydrogen Energy, CHEMICAL SCIENCES, Phase Transformation

The title dimanganese complexes react with NO (5% in N 2 ) at room temperature to give as major products the corresponding hexanitrosyl derivatives [Mn 2 (NO) 6 (m-L 2 )] in moderate yields, and they react rapidly with NO 2 to give the corresponding hydride derivatives [Mn 2 (m-H)(m-NO 2 )(CO) 6 (m-L 2 )], these having a nitrite ligand bridging the dimetal centre through the N and O atoms. The dppm-bridged dihydride also reacts selectively at 273 K with (PPN)NO 2 to give first the nitro derivative (PPN)[Mn 2 (m-H)(H)(NO 2 ) (CO) 6 (m-dppm)], which then transforms into the nitrosyl complex (PPN)[Mn 2 (m-CO)(CO) 5 (NO)(m-dppm)] at room temperature or above (dppm ¼ Ph 2 PCH 2 PPh 2 ; PPN þ ¼ [N(PPh 3 ) 2 ] þ ). The latter anion reacts with (NH 4 )PF 6 to give the hydride-bridged nitrosyl complex [Mn 2 (m-H)(m-NO)(CO) 6 (m-dppm)] and with [AuCl (PPh 3 )] to give the trinuclear cluster [AuMn 2 (m-NO)(CO) 6 (m-dppm)(PPh 3 )] (MneAu ¼ ca. 2.68 Å; Mn eMn ¼ 2.879(2) Å). Both products are derived from the addition of the added electrophile at the intermetallic bond and rearrangement of the nitrosyl ligand into a bridging position. In contrast, methylation of the anion with CF 3 SO 3 Me takes place at the nitrosyl ligand to yield the unstable methoxylimide derivative [Mn 2 (m-NOMe)(CO) 6 (m-dppm)]. Analogous reactions at the nitrosyl ligand take place upon the addition of HBF 4 $OEt 2 to the nitrosyl-bridged hydrides [Mn 2 (m-H)(m-NO)(CO) n (mdppm) m ] (n ¼ 6, m ¼ 1; n ¼ 4, m ¼ 2) to give the corresponding hydroxylimide derivatives [Mn 2 (m-H)(m-NOH)(CO) n (m-dppm) m ]BF 4 , which were also thermally unstable and could not be isolated nor fully characterized.

Heat and cold treatments using gel pack are commonly used to manage the soft tissue injury. To determine the best beans/grains that have cold and high temperatureholding capacity using the best fabric that can withstand the extreme changing temperatures. To determine the best characteristic between barley, rice and mung beans that can replace the ice and heat packs method. Rice, barley and mung beans were used in this study, the grains and beans were washed and dried under the sun light. Sterilization was done by roasting the grains and beans were roasted on a hot plate, to prevent them from seeding. All grains and beans were treated under UV light for an hour. The grains and beans were packed into a bag using a rib fabric, and these bags were 'cooked' using an autoclave (a machine that acts like a pressure cooker) with 121°C for 15 minutes. A small hole was made on each bag (that could fit a thermometer) to measured the holding capacity of the grains and beans. Rice grain differed 19°C in temperatures right after the bag was heated (RA) and after the bag was left for 20 minutes (+20) at room temperature in which the highest temperature for rice is 99°C. Barley grain differed 23°C between RA and +20 and its highest temperature is 99°C, while mung beans differed 26°C with its highest temperature 155°C. This shows that rice grains lost the least heat compared to other grains and beans. When freezing, Rice differed 5°C between RA and +20 and its lowest temperature is -6, while mung beans differed 7°C with its lowest temperature of -3°C and barley differed 1°C from its lowest temperature of -3°C. This shows that barley regained the least heat compared to the other grains. Rice has shown a superior characteristic compared to barley and mung beans. In terms of fabric, the rib fabric alone without the wool fabric is enough to detain and retain heat (5min + 155°C). The study has proven that rice which is covered with a rib fabric has similar characteristics with ice and hot pack and thus enhances the management of soft tissue injury.

- 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

The amount of catechins and caffeine in green tea are considered a standard of quality evaluation for green tea. The objectives of this study were to investigate the optimal conditions for simultaneous extraction of catechins and caffeine and to compare their quantity and composition within the exotic tea varieties. Moreover, 8 tea varieties of exotic origin were tested with the optimal extraction conditions found in this study. Regarding the caffeine and catechins contents, a 2 h room temperature extraction using a 2% phosphoric acid-40% EtOH solution was the most suitable simultaneous extraction method. The total catechins and caffeine contents of the tea leaves ranged 44.25-64.80 and 9.26-13.11 mg/g, respectively. The optimal extraction method of catechins and caffeine in tea leaves may be used for further studies and breeding of high quality tea plants.