Miracle-dz/UniFAR-FTUs huggingface dataset:
Pressure disturbances of different length scales interacting with conventional flames

The theory of large activation energy asymptotics is used to model the interaction of pressure disturbances characterised by different length scales with conventional flames. Byconventional flames it is understood that the deflagration Mach number is low and of the order of where 0 is the non dimensional activation energy and s is a positive power arising from the detail of a (global) kinetic scheme. By denoting the paper explores the coupling that exists between pressure disturbances and flames for medium to short wavelengths. that is with N in the range M −l to 1. The work complements that which has mainly been achieved assuming N ≫ M −1 (long wavelengths). As N becomes smaller the coupling from pre-heat and chemical zones becomes more pronounced. This work first deduces jump conditions across the flame zone for N ≈ M −1 with density variations included (up to now these have been ignored). The foundation is then laid for N ≈ 1/(02 M) (i.e. shorter wavelength) coupling and it is shown that a different un.
Noninvasive molecular identification of particulate matter in lungs by Raman microspectrometry

A new method for the analysis of particulate matter in lungs is proposed. It combines the exhaled breath condensate technique and Raman spectroscopy. The sampling method is noninvasive, which is suitable for the detection of occupational exposure to dust. The chemical composition of dust particles is assessed by Raman microspectroscopy. The effectiveness of this method as a means of identifying markers of occupational exposure to mica dust is evaluated. Copyright © 2011 John Wiley & Sons, Ltd.
Fabrication of a nanoporous dual‐electrode system for electrochemical redox cycling

Nanoporous electrodes are promising tools for highly sensitive electrochemical detection of molecules by redox cycling. In here, we report on a novel approach for the on‐chip fabrication of nanoporous dual‐electrode systems. The fabrication is based on template assisted dry etching into an electrode–insulator–electrode structure using a nanoporous alumina film as a mask. The mask itself is patterned by directly anodizing an aluminum layer on top of the chip. Homogeneous growth of the alumina nanopores on a wafer scale is achieved by adding a titanium intermediate film between the top electrode and the aluminum substrate as a stopping layer. The resulting electrodes are separated by approximately 100 nm and have pore diameters in the range of 30–50 nm. Thus they are ideally suited for redox cycling experiments based on fast diffusion of molecules between the electrodes. Integrating this process into microfabricated electrode structures promises to yield a stable and sensitive electrochemical sensor platform.
Effect of Volumetric Ratio and Injection Pressure on Water-Liquid Nitrogen Interaction

To simulate the fuel-coolant interaction under the easily controllable condition, the water and the liquid nitrogen were used respectively as the molten fuel and the coolant in this study. To initiate the interaction, the water was injected into the cylindrical chamber to come into contact with the liquid nitrogen. The experiments were conducted with two key parameters, the water/liquid nitrogen volumetric ratio and the water injection pressure, to study their effects on the interaction. The experiments were conducted at the different water injection pressures with various initial volumetric ratios for water and liquid nitrogen. The pressure spikes and the ice debris observed from the experiments confirmed the existence of the strong interaction between the water and the liquid nitrogen. The occurrence of the pressure spikes and the times of their inceptions at the different conditions were used to create a diagram to indicate the preferable conditions for the strong interaction. The propagation speed of an observed pressure spike was estimated to be comparable to the theoretical sound speed of the liquid nitrogen/nitrogen vapor mixture. This result suggested the possibility of the vapor explosion interaction between the water and the liquid nitrogen similar to that observed in the fuel-coolant interaction.
Reflections on African science education for the new millennium: The case of the Ethiopian chemistry curriculum for beginners

Science education in Africa has been criticized for more than three decades. In response to the wide spread dissatisfaction with the educational system, Ethiopia has administered three different educational reforms to make the curricula relevant to the day to day life of the learners. The question is to what extent this general educational objective has been translated into appropriate content and instructional strategies. This research attempts to qualitatively analyse and reflect on the newly introduced chemistry curriculum for beginners at grade 7 (age 13) in Ethiopian primary schools. Primary school chemistry teachers in Addis Ababa participated in the research project through group discussion and questionnaire. They considered questions of relevance and appropriateness of content to the target pupils. Although science education research seem to influence the formulation of objectives at policy level, its impact on content and methodology is not yet satisfactory.
Interfacial adhesion of lignocellulosic materials in polymer composites: an overview

Cellulosic materials have long been used as cost-cutting fillers in the plastic industry. Among the various factors which determine the final performance of the composite materials depend, to a large extent, on the adhesion between the polymer matrix and the reinforcements, and, therefore, on the quality of the interface. In fact, the majority of cellulosic raw materials are lignocellulosics of different polarity to plastics, and due to this divergent behavior, the adhesion between cellulosic materials and polymer matrices is very poor. However, a sufficient degree of interaction or adhesion between the surface of the cellulosic materials and matrix resin is usually desired to achieve an optimum performance of the end-product. In many cases surface modification of the cellulosics or the matrix resins, using various additives, vinyl monomers, or coupling agents, are considered to be essential to achieve this goal. The present paper surveys research work published in this field with special emphasis on the .
Thin Film Transistors with Graded SiN x Gate Dielectrics

This paper presents results on thin film transistors with graded SiN x gate dielectrics. All SiN x and a-Si:H films were prepared using 250 o C plasma-enhanced chemical vapor deposition processes. Device characteristics such as mobility, threshold voltage, subthreshold slope, and on/off current are discussed. The graded gate dielectric thin film transistor (TFT) may have better or worse device performance compared with the single gate dielectric TFT, depending on the interface dielectric deposition condition
l-Lysine-Assisted Synthesis of ZrO2 Nanocrystals and Their Application in Photocatalysis

Nanocrystalline ZrO2 with narrow size distribution and mean size ∼8 nm has been synthesized by the l-lysine-assisted hydrothermal method. The structural and morphological characterizations were studied by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM), and physicochemical characterizations were carried out by using infrared spectra (IR), UV−vis spectra, and photoluminescence (PL) spectra. On the basis of the choice of synthesis parameters, monoclinic (m-) and tetragonal (t-) phases of ZrO2 coexisted with a size ∼8 nm. This is an important result with respect to application in catalytic properties of nanocryalline ZrO2. The possible nucleation and growth process is also discussed.
RETENTION OF IONS IN A MAGNETIC CHROMATOGRAPH USING HIGH-INTENSITY AND HIGH-GRADIENT MAGNETIC FIELDS

The control of the retention and separability of samples to be analyzed with high performance liquid chromatography systems is difficult, and usually requires exchanging of the mobile phase and/or the column. We developed a magnetic chromatography (MC) system, which does not require regular exchanging of the mobile phase and/or the column, and uses a continuous-flow system to separate multiple ionic species with different magnetic properties. To demonstrate experimentally the feasibility of such an MC system, we measured the retention of ions in the MC system for aqueous solutions of either pure NaI, CuSO4, NiCl2, CrCl3, or CoCl2. We applied magnetic fields varying from 0 to 3 T to the aqueous solution of transition element cations and anions flowing in an MC system, and demonstrated that the retention time was delayed by about 20 min, and that for Co(II) the chromatogram broadened with increase in the applied magnetic field intensity (H). Furthermore, our results suggest that for ionized transition elements with a larger Bohr magneton number, the retention time in MC systems becomes longer. We derived experimentally a retention factor, k, that can be simply expressed in terms of an MC parameter, p MCH , which is the product of the Bohr magneton number, the concentration of the cations, and H. The MC parameter can be used to correlate all experimental data in terms of k, as k= 0.0014p MCH 1.47. Hence, k is proportional to about 3/2 power of the MC parameter. We therefore confirmed that there is a significant effect of high-intensity, high-gradient magnetic fields on the behavior of paramagnetic cations in water.
Untersuchungen an substituierten 7‐Methyl‐furochromonen; Khellin und Visnagin

Alkalihalogenide entmethylieren Khellin (3a) und Visnagin (3b) zu Desmethyl-khellin (3c) und Desmethyl-visnagin (3d). Diese werden in Carbamidsaureester 3e–j ubergefuhrt. — Die Enamine 5e–k entstehen durch Einwirkung langkettiger primarer aliphatischer Amine auf 6-Hydroxy-4-methoxy-5-acetoacetyl-benzofuran (4b) und die analoge 4.7-Dimethoxy-Verbindung 4d. Visnagin und Khellin selbst sind diesen Reagenzien gegenuber stabil.
Kinetic Study of Methyl Palmitate Oxidation in a Jet-Stirred Reactor and an Opposed-Flow Diffusion Flame Using a Semidetailed Mechanism

Methyl palmitate is a long-chain methyl ester and a major constituent of palm-oil-derived biodiesel. A detailed mechanism for its combustion was recently developed by Herbinet and coworkers. This detailed mechanism involves 4442 species and 30,425 reactions, which makes it too complex for direct use in flame structure modeling, for instance, in studies of one-dimensional laminar opposed-flow diffusion flames. We used the improved directed relation graph method to derive a skeletal biodiesel combustion mechanism that retains the key properties of the detailed mechanism including auto-ignition behaviors and extinction temperature profiles of stoichiometric methyl palmitate/air mixture at pressures of 1–100 atm. The initial temperatures for ignition were from 600 to 1600 K. This skeletal mechanism, containing only 402 species and 2503 reactions, was used to study methyl palmitate conversion rates and key species profiles in a jet-stirred reactor and an opposed-flow diffusion flame at atmospheric pressure and stoichiometric fuel/oxidizer conditions. Supplemental materials are available for this article. Go to the publisher's online edition of Combustion Science and Technology to view the free supplemental file.
Synthesis and pH- and salinity-controlled self-assembly of novel amphiphilic block-gradient copolymers of styrene and acrylic acid

A novel type of amphiphilic ionic copolymer comprising a hydrophilic poly(acrylic acid) (PAA) block and an amphiphilic poly(acrylic acid)-grad-poly(styrene) (PAA-grad-PS) copolymer block was synthesized using a one step direct nitroxide-mediated polymerization (NMP). A strong influence of the macroinitiator on the values of the reactivity ratios of the co-monomers is confirmed by 1H NMR. The aggregation behaviour of the copolymers in the aqueous medium was studied by small-angle neutron scattering (SANS) and dynamic light scattering (DLS) and by transmission electron microscopy (TEM) in a wide range of pHs and ionic strengths. It has been demonstrated that PAA-b-(PAA-grad-PS) copolymers are soluble in alkaline water at room temperature without the special experimental procedures (addition of co-solvent, heating, etc.) that are usually required for solubilisation of classical PAA-b-PS diblock copolymers. The self-assembly of the PAA-b-(PAA-grad-PS) copolymers into nano-scale aggregates at low/moderate pH and/or high ionic strength was demonstrated by SANS and DLS experiments. The SANS spectra for the copolymer solution exhibit a correlation peak pointing to the formation of micelles with repulsive coronae. TEM images indicate that the micelles have an approximately spherical shape and exhibit a wide size distribution. Our results prove, that in contrast to “frozen” aggregates formed by PAA-b-PS copolymers in aqueous media, the micelles of PAA-b-(PAA-grad-PS) amphiphilic copolymers exhibit “dynamic” pH-responsive properties, i.e. they can reversibly change their aggregation number upon a variation in the pH or salinity of the solution.
Systematic investigation of the barrier discharge operation in helium, nitrogen, and mixtures: discharge development, formation and decay of surface charges

As a logical extension to previous investigations of the barrier discharge (BD) in helium and nitrogen, the present work reports on the operation in any mixtures of both pure gases. Using a well-established plane-parallel discharge cell configuration allows to study the influence of the He/N2 mixing ratio on the formation of different discharge modes. Their characterization was made by measuring the discharge emission development together with the formation and decay of surface charges on a bismuth silicon oxide (Bi12SiO20, BSO) crystal. This was realized by the simultaneous application of the spatio-temporally resolved optical emission spectroscopy, and the electro-optic Pockels effect in combination with a CCD high speed camera. The existence diagram for diffuse and filamentary BDs was determined by varying the amplitude and shape of the applied voltage. Over the entire range of the He/N2 ratio, the diffuse mode can be operated at moderate voltage amplitudes whereas filamentation occurs at significant overvoltage and is favoured by a high voltage slew rate. Irrespective of the discharge mode, the overall charge transfer during a discharge breakdown is found to be in excellent agreement with the amount of accumulated surface charges. An exponential decay of the surface charge deposited on the BSO crystal is induced by LED illumination beyond a typical discharge cycle. During the decay process, a broadening of the radial profiles of positive as well as negative surface charge spots originating from previous microdischarges is observed. The investigations contribute to a better understanding of the charge accumulation at a dielectric.
Reduction of resazurin to resorufin catalyzed by gold nanoparticles: dramatic reaction acceleration by laser or LED plasmon excitation

Plasmon excitation (532 nm) of gold nanoparticles in the presence of resazurin and hydroxylamine leads to their photocatalytic reduction to resorufin with great efficiency. In the case of laser excitation under laser-drop conditions the process is essentially complete following an ∼8 ns laser pulse at 532 nm. Excitation with LED sources at ∼530 nm proves to be a simple and cost efficient way to promote plasmon-assisted reactions. We propose that the catalytic reaction is thermally activated by the gold nanoparticle and takes advantage of the high temperatures achievable under plasmon excitation.
An Aerosol Chemical Speciation Monitor (ACSM) for Routine Monitoring of the Composition and Mass Concentrations of Ambient Aerosol

We present a new instrument, the Aerosol Chemical Speciation Monitor (ACSM), which routinely characterizes and monitors the mass and chemical composition of non-refractory submicron particulate matter in real time. Under ambient conditions, mass concentrations of particulate organics, sulfate, nitrate, ammonium, and chloride are obtained with a detection limit <0.2 μg/m3 for 30 min of signal averaging. The ACSM is built upon the same technology as the widely used Aerodyne Aerosol Mass Spectrometer (AMS), in which an aerodynamic particle focusing lens is combined with high vacuum thermal particle vaporization, electron impact ionization, and mass spectrometry. Modifications in the ACSM design, however, allow it to be smaller, lower cost, and simpler to operate than the AMS. The ACSM is also capable of routine stable operation for long periods of time (months). Results from a field measurement campaign in Queens, NY where the ACSM operated unattended and continuously for 8 weeks, are presented. ACSM data is analyzed with the same well-developed techniques that are used for the AMS. Trends in the ACSM mass concentrations observed during the Queens, NY study compare well with those from co-located instruments. Positive Matrix Factorization (PMF) of the ACSM organic aerosol spectra extracts two components: hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA). The mass spectra and time trends of both components correlate well with PMF results obtained from a co-located high resolution time-of-flight AMS instrument.
An improved N-body semi-empirical model for body-centred cubic transition metals

Abstract The recently published semi-empirical potentials of Finnis and Sinclair for the metals V, Nb, Ta, Mo and W appear to give unphysical results for properties involving small interatomic separation. This is remedied by adding to the potentials cores fitted to electron gas calculations on dimers. The adjusted potentials are shown to predict a more realistic pressure-volume relationship. Interstitial formation energies are calculated for various configurations, using quenched molecular dynamics and static relaxation. Some preliminary results on interstitial migration are presented.
Topochemical studies. XII. Structure of a cinnamamide–cinnamic acid (1/1) complex

C 9 H 9 NO.C 9 H 8 O 2 cristallise dans P2 1 /a avec a=40,183, b=9,5084, c=4,0569 A, β=97,540°, Z=4; affinement jusqu'a R=0,058. Les molecules de cinnamamide et d'acide cinnamique sont maintenues ensemble par deux types de liaisons hydrogene entre les groupes amide et carboxyle, formant ainsi un dimere. Possibilite de la formation de photodimeres de type β
Divertor conditions relevant for fusion reactors achieved with linear plasma generator

Intense magnetized hydrogen and deuterium plasmas have been produced with electron densities up to 3.6 × 1020 m−3 and electron temperatures up to 3.7 eV with a linear plasma generator. Exposure of a W target has led to average heat and particle flux densities well in excess of 4 MW m−2 and 1024 m−2 s−1, respectively. We have shown that the plasma surface interactions are dominated by the incoming ions. The achieved conditions correspond very well to the projected conditions at the divertor strike zones of fusion reactors such as ITER. In addition, the machine has an unprecedented high gas efficiency.
Effect of O2(a1Δg) on plasma structures in oxygen radio frequency discharges

Oxygen rf glow discharges between parallel plates were numerically analyzed by using the relaxation continuum model. The result at a frequency of 13.56 MHz, sustaining voltage of 150–350 sin ωt V, pressure of 0.15–1.0 Torr, and stainless steel surface, shows that O2(a1Δg) has a number density that is an order of magnitude larger than that of atomic oxygen. The plasma density as a function of pressure has a maximum at about 0.2 Torr, and decreases with increasing pressure due to the increase in the net rate of associative detachment from O− by O2(a1Δg). The comparison between the discharges in two surface materials, stainless steel and copper, indicates that the number densities of O2(a1Δg) and atomic oxygen strongly depend on the surface loss probability, and that consequently the plasma density is also changed by replacing the surface material.
Influence of laser lift-off on optical and structural properties of InGaN/GaN vertical blue light emitting diodes

The influences of the laser lift-off (LLO) process on the InGaN/GaN blue light emitting diode (LED) structures, grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition, have been comprehensively investigated. The vertical LED structures on Cu carriers are fabricated using electroplating, LLO, and inductively coupled plasma etching processes sequentially. A detailed study is performed on the variation of defect concentration and optical properties, before and after the LLO process, employing high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) observations, cathodoluminescence (CL), photoluminescence (PL), and high-resolution X-ray diffraction (HRXRD) measurements. The SEM observations on the distribution of dislocations after the LLO show well that even the GaN layer near to the multiple quantum wells (MQWs) is damaged. The CL measurements reveal that the peak energy of the InGaN/GaN MQW emission exhibits a blue-shift after the LLO proces.
Adsorption of selected ions on the anatase TiO2 (101) surface: a density-functional study

Density-functional calculations of adsorption of the F− and OH− ions on the TiO2 anatase (101) surface have been performed. Changes to the electronic properties prior to and after adsorption have been investigated. The most profound change in the electronic structure of the anatase surface after adsorption is the diminishing of the band gap of the system. While for the pure (without adsorbents) surface the band gap is 1.77 eV wide, for the modified surface with the F− and OH− ions the band gap widths equal to 0.35 and 0.39 eV, respectively. That means, the excitation energy after adsorption is over four times smaller than in the case of pure system. Nevertheless, in all the cases studied the anatase surface maintains its semiconducting properties.
Solvent Property Characterization of Poly(ethylene glycol)/Dextran Aqueous Biphasic Systems Using the Free Energy of Transfer of a Methylene Group and a Linear Solvation Energy Relationship

Aqueous biphasic systems (ABSs) composed of poly(ethylene glycol) (PEG) and dextran have long been proposed as useful liquid/liquid extraction systems for biological macromolecules. More recently, they have been proposed as useful partitioning systems for molecular characterization in quantitative structure activity relationships. In this context, the distribution ratios of a wide range of organic solutes differing in structure and functionality were measured in a PEG/dextran ABS and the results compared to the corresponding 1-octanol/water partition coefficients. The relative hydrophobicity of the phases was quantified from the free energy of transfer of a methylene group measured for a homologous series of alcohols. A linear free energy relationship based on Abraham's generalized solvation equation has been derived from the solute partitioning data, which allows a direct comparison to be made between the solvent properties of a PEG/dextran ABS and those of traditional solvent/water systems used, for exa.
An Electronic Version of Pavlov's Dog

Neuromorphic plasticity is the basic platform for learning in biological systems and is considered as the unique concept in the brains of vertebrates, which outperform today's most powerful digital computers when it comes to cognitive and recognition tasks. An emerging task in the field of neuromorphic engineering is to mimic neural pathways via elegant technological approaches to close the gap between biological and digital computing. In this respect, functional, memristive devices are considered promising candidates with yet unknown benefit for neuromorphic circuits. It is demonstrated that a single Pt/Ge0.3Se0. 7/SiO2/Cu memristive device implemented in an analogue circuitry mimics non‐associative and associative types of learning. For Pavlovian conditioning, different threshold voltages for the memristive device and the comparator are essential. Similarities to neurobiological correlates of learning are discussed in the framework of hebbian learning rule, plasticity, and long‐term potentiation.