Miracle-dz/UniFAR-FTUs huggingface dataset:
A Numerical and Analytical Study of Detonation Diffraction

An investigation of detonation diffraction through an abrupt area change has been carried out via two-dimensional, parallel simulations. The existence of critical conditions for successful diffraction is closely related to the occurrence of localized re-initiation mechanisms, and is relevant to propulsion and safety concepts concerning detonation transmission. Our analysis is specialized to a reactive mixture with perfect gas equation of state and a single-step reaction in the Arrhenius form. The concept of shock decoupling from the reaction zone is the simplest idea used to explain the behavior of a diffracting detonation front. Lagrangian particles are injected into the flow in order to identify the dominant terms in the equation that describes the temperature rate of change of a fluid element, expressed in a shock-based reference system. Conveniently simplified, this equation provides an insight into the competition between the energy release rate and the expansion rate behind the diffracting front. We also examine the mechanism of spontaneous generation of transverse waves along the front. This mechanism is related to the sensitivity of the reaction rate to temperature, and it is investigated in the form of a parametric study for the activation energy. We study in detail three highly resolved cases of detonation diffraction that illustrate different types of behavior, super-, sub-, and near-critical diffraction. We review the applicability of existing shock dynamics models to the corner-turning problem. Numerical results from the parametric study are compared with predictions from these theories in the attempt to find a formula for shock decay in a quenching detonation. This estimate is then used in the simplified temperature rate of change equation to provide a relation between critical channel width and activation energy. We conclude this study by examining the spontaneous formation of transverse waves along the wavefront of a successfully transmitted detonation. The problem is simplified to a planar CJ detonation moving in a channel over a small obstacle to investigate how acoustic waves propagate within the reaction zone. Depending on the reaction kinetics, we show that such waves may be amplified due to feedback between the chemical reaction and fluid motion. The amplification can lead to shock steepening and formation of transverse detonation waves.
Field emission properties of Fe70Pt30 catalysed multiwalled carbon nanotubes

Multi-walled carbon nanotubes were grown on nanocrystalline Fe70Pt30 film using low-pressure chemical vapour deposition (LPCVD) method. The growth time was varied between 5 min to 30 min. SEM micrograph of this film revealed that the size of nanoparticles varied from 5 nm to 10 nm. The diameter of the carbon nanotubes varied from 20 nm to 50 nm as verified by TEM. HRTEM image confirmed that the carbon nanotubes are bamboo-shaped multiwalled carbon nanotubes (MWNTs). Field emission characteristics of MWNTs at various growth times (5 min, 15 min and 30 min) with working distances (50 µm, 100 µm and 150 µm) were also studied. The carbon nanotubes grown for 30 min with working distance 150 µm exhibited the lowest turn-on field of 2.45 V/µm. The turn-on field increases from 2.45 V/µm to 6.21 V/µm as the growth time decreases from 30 min to 5 min whereas for lower working distances (100 µm and 50 µm), the turn-on field increases from 4.74 V/µm to 6.74 V/µm and from 8.79 V/µm to 14.49 V/µm respectively. The turn-on field (E to) and field enhancement factor (β) were studied as a function working distance (d) and growth time respectively to see the effect of these parameters on field emission properties. The field enhancement factor (β) was also studied as a function of radius of apex curvature (r) . It was found the field enhancement factor (β) decreases with the increase in radius of apex curvature (r) and growth time whereas the value of field enhancement factor (β) increases as working distance (d) increases. On the basis of the dependence of β on radius of apex curvature (r) a relationship of β ∝ r −1/2 is fitted.
Ultrasound‐Assisted Preparation of Molecularly Imprinted Polymers: Effects on Polymer Morphology, Binding, and Chromatographic Behavior

Abstract The influence of sonication on the preparation of molecularly imprinted polymers (MIPs) toward theophylline has been studied. The study showed that MIPs prepared in an ultrasonic bath operating at 35 kHz displayed binding and separation characteristics similar to those of the reference MIPs prepared using more traditional protocols. The data illustrates how well the prepolymerization complexes formed in solution prior to polymerization survive the effects of cavitations induced in the liquid. Furthermore, the results show that sonication can be used as a tool for the preparation of MIPs, thus offering the chemist a way of increasing the solubility of troublesome templates. Sonication also presents an opportunity to achieve aided initiation and effective degassing without sacrificing binding capacity or rigidity.
Rôles des instabilités électroniques de dérive dans le transport électronique du propulseur à effet hall

Le propulseur a effet Hall est un moteur a plasma utilise pour le maintien en orbite et le controle d'attitude de satellites, et les petites missions interplanetaires. Son principe est base sur une configuration de champs electrique et magnetique croises pour accelerer des ions a hautes vitesses et creer ainsi une poussee. Le confinement des electrons dans une telle configuration, crucial pour son bon fonctionnement, pose le probleme theorique de leur transport au travers des lignes de champ magnetique, la diffusion classique due aux collisions electron-neutre etant insuffisante. Ce travail de these fait la lumiere sur un mecanisme de transport electronique anormal (par opposition a la diffusion classique) par la mise en evidence d'instabilites electroniques de derive de frequence 10-40 MHz et de longueurs d'onde de l'ordre du rayon de Larmor electronique (millimetrique) se developpant en paquets de modes perpendiculaires au champ magnetique. Ces instabilites, generees par un couplage entre le mouvement cyclotronique des electrons et leur derive, sont a l'origine d'un processus de diffusion stochastique electronique au travers des lignes de champ magnetique dont les proprietes sont proches de celles attendues dans le cadre du transport anormal.
Steady-state luminescence measurement for qualitative identification of rare earth ions in minerals

Minerals are the source of rare earth elements (REE), and knowledge of the amount of REE in different minerals is necessary for a mineralogist. We propose steady - state luminescence measurement as a quick and non - destructive method for detecting several lanthanide ions present together in the same sample. By using excitation and emission spectra of each 4f ion, rare earth ions could be easily identified. The most intense emission lines in the UV - VIS range are 336 nm for Ce 3+ , 420 nm for Eu 2+ , 596 - 649 nm for Pr 3+ and Sm 3+ , 614 - 617 nm for Eu 3+ , at 478 and 573 - 579 nm for Dy 3+ , and 520 - 550 nm for Er 3+ and Ho 3+ ions. We have verified that the best excita tion wavelength for each ion as follows: for Ce 3+ and Eu 2+ , 295 nm and 336 nm; for Pr 3+ , 442 nm; for Sm 3+ , 399 - 408 nm; for Eu 3+ , 393 - 395 nm; for Dy 3+ , 348 nm; for Er 3+ , 377 nm; and for Ho 3+ , 415 nm.
Effect of Bromide Ion on Haloacetic Acid Speciation Resulting from Chlorination and Chloramination of Aquatic Humic Substances

The objective of this study was to investigate the effect of bromide ion on the distribution of haloacetic acid (HAA) species resulting from the chlorination and chloramination of waters containing aquatic humic substances. Aquatic humic substances were extracted from a surface water and a groundwater and were chlorinated and chloraminated under standard conditions at pH 8 and pH 6 in the presence of bromide concentrations ranging from 0 to 25 μM (0−2 mg/L). The treated waters were analyzed for all nine of the HAA species containing bromine and chlorine. Standards for bromodichloroacetic acid and dibromochloroacetic acid were not commercially available but were synthesized for use in this study. Bromochloro-, bromodichloro-, and dibromochloroacetic acid were readily formed and constituted at least 10% of the total HAA concentration in waters containing as little as 1.2 μM (0.1 mg/L) bromide. The mixed bromochloro HAA species were major components of the total HAA concentration at bromide concentrations fo.
Effects of ethephon on growth and yield of sweet sorghum.

There is little information about the effects of ethephon ripening hormone on the yield of sweet sorghum in Thailand. Therefore, this study aimed to evaluate the impact of ethephon hormone applied at different growth stages of three cultivars of sweet sorghum on its growth and yield. The experiment was conducted from December 2016 to May 2017 at a research plot of the Faculty of Agricultural Technology, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand. The experiment was designed as a split-plot design with three replications. Three sweet sorghum cultivars (Ethanol 2, KKU 40, and Cowley) were planted in the main plot. Ethephon was applied at five stages of growth of these cultivars: heading stage, panicle stage, milking stage, dough stage, harvesting stage. Ethephon applications at those stages and untreated control were the subplots. Results showed that Ethanol 2 cultivar exhibited a higher growth rate, plant height, stem diameter, grain yield, stem fresh weight, and yield, juice extract yield, and sugar content than those exhibited by KKU 40 and Cowley. Application of ethephon at the heading stage gave the lowest stem diameter, grain yield, stem fresh weight, and yield, whereas applying it at the harvesting stage gave the highest sugar yield. There were no significant correlations between sweet sorghum cultivars and the growth stages at which ethephon was applied. Based on these results, it might be concluded that Ethanol 2 cultivar should be treated with ethephon hormone at its harvesting stage.
Preparation and Characterization of Microcapsules Containing Lemon Oil

Abstract Urea–formaldehyde microcapsules were prepared by in situ interfacial polymerization to lemon oil as the core material using four kinds of emulsifier, gelatin, span 80, polyvinyl alcohol, and sodium dodecyl sulfate. Urea–formaldehyde types were investigated for their effects on thermal properties, mean particle size, and size distributions. Thermal properties were studied using a dynamic DSC and TGA analysis. The morphology and particle distributions of microcapsules were determined using an image analyzer. As experimental results, the diameters and distribution ranges of the microcapsules were decreased with increasing stirring rate and stirring time. In the presence of up to 5 g of emulsifier in 100 ml of deionized water, the mean diameter decreased, and then it increased as the emulsifier increased, resulting from increasing viscosity. The mean size of the microcapsules was related to the viscosity and reunification of core materials. That is, the mean size increased up to 22.8 cP due to increased the viscosity. But, at 30 cP, the mean size of the microcapsules decreased, as a consequence of the interruption of the reunion of core materials by the high viscosity of the core materials.
Infrared and Raman Spectra of Inorganic and Coordination Compounds

Inorganic molecules (ions) and ligands are classified into diatomic, triatomic, four-atomic, five-atomic, six-atomic, and seven-atomic types, and their normal modes of vibration are illustrated and the corresponding vibrational frequencies are listed for each type. Molecules of other types are grouped into compounds of boron, carbon, silicon, nitrogen, phosphorus, and sulfur, and the structures and infrared (IR)/Raman spectra of select examples are shown for each group. Group frequency charts including band assignments are shown for phosphorus and sulfur compounds. Other group frequency charts include hydrogen stretching frequencies, halogen stretching frequencies, oxygen stretching and bending frequencies, inorganic ions, and metal complexes containing simple coordinating ligands. Keywords: inorganic compounds; coordination compounds; diatomic molecules (ligands); triatomic molecules (ligands); four-atomic molecules (ligands); five-atomic molecules (ligands); six-atomic molecules (ligands); seven-atomic molecules (ligands); boron compounds; carbon compounds; silicon compounds; nitrogen compounds; phosphorus compounds; sulfur compounds; group frequency charts
New Core-Shell Type Polymeric Supports Based on the Amberlite XAD-4 Adsorbent: A Novel Synthesis Procedure

The chloromethyl groups have been introduced into commercial S/DVB copolymer matrixes via interpenetrating polymer networks (IPN) synthesis. The procedure involves impregnation of the Amberlite XAD-4 adsorbent, with use of the vinylbenzyl chloride (VBC) and divinylbenzene (DVB) monomers mixture, and suspension polymerization process. The syntheses were evaluated by FT-IR spectra and SEM analyses and furthermore by chlorine content determination as well as characterization of porous structure by nitrogen adsorption at liquid nitrogen temperature. Designed synthesis approach allowed determining organic and water phases composition. Furthermore, impact of an excess of the organic phase removal method has been investigated. Basing on the obtained results it could be stated that the chloromethyl groups, derived from VBC monomer, were successfully introduced into the XAD-4 structure. Captured SEM images revealed significant changes in the beads' surface morphology after polymerization processes. The presented studies reveal designed and executed synthesis processes, which involve the use of a proper water phase and excess of organic phase removal. Observed changes in the beads' morphology suggest that introduced functionalities are concentrated on the porous surface of the XAD-4 adsorbent.
Application of dissolved air flotation as pretreatment of seawater desalination

The performance of dissolved air flotation (DAF) was evaluated for pretreatment of seawater desalination in this study. For this purpose, DAF was compared with dual medial filtration (DMF) for its performance of particle removal and organic reduction through pilot-scale experiments. A pilot-scale DAF plant with capacity of 3.2 m3/h was installed at southern coast of the East Sea and operated for four months (June–September, 2009). According to this study results, the organic reduction performance of DAF was comparable to that of DMF. Both DAF and DMF removed the same organic fraction. However, DAF could not match DMF in particle removal. The association of DAF and DMF could improve the pretreatment performance and better filtrate quality was obtained in terms of particle removal. The association reduced the clogging head loss and initial turbidity breakthrough.
Fatty Acid Based Biodegradable Polymer

Synthetic polymers have become an indispensable part of the daily‐life of human beings and the biodegradable class of polymers hold immense value in therapeutics. Fatty acid incorporation in biodegradable polymers renders flexibility, low melting point, hydrophobicity, and pliability properties. At the same time, degradation into naturally occurring compounds makes them environmentally friendly besides their utility in various applications like drug delivery and as implantable devices. Fatty acid monomers are integrated in the polymeric chain using carboxylic acid functional groups. Most fatty acids are monofunctional in nature and act only as chain terminator during polymerization. This limitation has been overcome by the dimerization of unsaturated fatty acids or by creating a functional group on the monomers. The most recent addition to this series is ricinoleic acid based polyanhydrides and copolyesters. In this article, the synthesis methods, the physical properties, the degradation, the stability, and the toxicological aspect and applications of each class of fatty acid based polymers are discussed.
Surface Fractal Dimension of Less-Crystalline Carbon Micropore Walls

The texture of pore walls of activated carbon fiber (ACF) treated at a high temperature in Ar was evaluated by surface fractal analysis using two kinds of molecular probe methods. The multiprobe (MP) method using the monolayer capacity of several different probe systems gave evidence for a decrease in the fractal dimension of the micropore walls with an increase in pretreatment temperature. As the BET monolayer gave unrealistic fractal dimension due to an erroneous evaluation of the monolayer in the micropore, this work proposed a new evaluation method of the monolayer in the micropore using the pore volume, average pore width, and molecular radius from the αs and DR analyses. The single-probe (SP) method developed by Avnir and Jaroniec detects nitrogen and benzene adsorption isotherms. The surface fractal dimension by the MP method was between the surface fractal dimensions determined by the SP method using nitrogen and benzene. The surface fractal dimension sensitive to the probe molecule indicated the .
Synthese von cis‐ und trans‐3‐Phenoxyprolin

Allylbromierung des 1,2-Dehydroprolinesters 4 und Umsetzung des entsprechenden Bromimins 3 mit Thalliumphenolat gibt den 3-Phenoxy-1,2-dehydroprolin-methylester (9). Reduktionsversuche an 9 sowie 10 werden beschrieben und fuhren im gunstigsten Fall zu einer Mischung der entsprechenden cis/trans-isomeren Proline 11a und 11b im Verhaltnis 2:3. Ausgehend von 3 wird eine“Eintopf”-Reaktion zur Darstellung von 7a beschrieben. Synthesis of cis- and trans-3-Phenoxyproline** Allylic bromination of the 1,2-dehydroproline ester 4 and reaction of the resulting bromoimine 3 with thallium phenolate affords 3-phenoxy-1,2-dehydroproline methyl ester (9). Reduction experiments with 9 and 10 are described, which lead in the most favorable case to a mixture of the corresponding cis/trans-isomeric prolines 11a and 11b in a ratio of 2:3. A “one-pot” procedure starting from 3 is described for the preparation of 7a.
Physical and Chemical Characterization of Particles in the Upper Troposphere and Lower Stratosphere: Microanalysis of Aerosol Impactor Samples

Herein is reported activities to support the characterization of the aerosol in the upper troposphere (UT) and lower stratosphere (LS) collected during the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA) missions in 1994. Through a companion proposal, another group was to measure the size distribution of aerosols in the 0.008 to 2 micrometer diameter range and to collect for us impactor samples of particles larger than about 0.02 gm. In the first year, we conducted laboratory studies related to particulate deposition patterns on our collection substrates, and have performed the analysis of many ASHOE/MAESA aerosol samples from 1994 using analytical electron microscopy (AEM). We have been building an "aerosol climatology" with these data that documents the types and relative abundances of particles observed at different latitudes and altitudes. The second year (and non-funded extension periods) saw continued analyses of impactor aerosol samples, including more ASHOE/MAESA samples, some northern hemisphere samples from the NASA Stratospheric Photochemistry Aerosols and Dynamics Expedition (SPADE) program for comparison, and a few aerosol samples from the NASA Stratospheric TRacers of Atmospheric Transport (STRAT) program. A high-resolution field emission microscope was used for the analysis and re-analysis of a number of samples to determine if this instrument was superior in performance to our conventional electron microscope. In addition, some basic laboratory studies were conducted to determine the minimum detectable and analyzable particle size for different types of aerosols. In all, 61 aerosol samples were analyzed, with a total of over 30,000 individual particle analyses. In all analyzed samples, sulfate particles comprised the major aerosol number fraction. It must be stressed that particles composed of more than one species, for example sulfate and organic carbon, were classified according to the major fraction. Thus, many of the particles classified as sulfate may have contained significant mass fractions of carbonaceous or other material. These particles for the most part did not show two physical phases, however. Nonsulfate particles were classified according to the physical and chemical characteristics of each particle, and were grouped into the major nonsulfate particle classes, including C-rich, crustal, metallic, and salts. Our UT and LS sample analyses indicate a maximum for crustal and C-rich particle abundance in the Northern Hemisphere upper troposphere, and a salt particle maximum in the Southern Hemisphere upper troposphere. Metallic particles are clearly more prevalent in the troposphere than in the stratosphere, but interhemispheric differences appear small.
Utilisation of solid phase extraction procedures for preconcentration and determination of vanadium and chromium in various types of water samples by atomic absorption spectrometry

In the present work, sensitive and simple methods for determination of vanadium (V) by electrothermal atomic absorption spectrometry (ETAAS) and for determination of chromium (VI) by flame atomic absorption spectrometry (FAAS) after selective preconcentration by solid phase extraction (SPE) on a Chromabond® NH2 column have been developed. The first procedure for the preconcentration of vanadium (V) is based on the adsorption of vanadium (V) as chelate with Alizarin Red S on the sorbent at pH 5.5. The second procedure was utilised for preconcentration of chromium (VI) and also for speciation of chromium (III) and chromium (VI) using the same column at pH 5.5 without chelating agent. The influence of various experimental variables affecting the recovery of SPE procedure, i.e. pH of the sample solution, concentration of chelating agent as well as volume and concentration of elution solution, were investigated. Under the optimised experimental conditions, the detection limits (calculated as three times the standard deviation (SD) of the blank signal, divided by the slope of the calibration graph) for vanadium (V) and chromium (VI) were 0.11 and 11.7 µg L−1, respectively. The developed methods were applied successfully to the determination of vanadium (V) and chromium (VI) in different water samples.
Comparison of effects of phosphorus sources on soil acidity, available phosphorus and maize yields at two sites in western Kenya

The effects of farmyard manure (FYM), Tithonia diversifolia (tithonia) and urea when applied alone or in combination with Minjingu phosphate rock (MPR), Busumbu phosphate rock (BPR) or triple superphosphate (TSP) on soil acidity, P availability, maize yields and financial benefits were evaluated at Bukura and Kakamega in western Kenya. A reduction in exchangeable acidity and Al was observed in most tithonia- and FYM-treated soils, but not with inorganic P sources when applied in combination with urea. The effectiveness in increasing available soil P followed the order; TSP > MPR > BPR among inorganic P sources, and FYM > tithonia among organic materials at both sites. At Bukura, a site higher in both available P and Al saturation compared with Kakamega, maize did not respond to inorganic P sources applied in combination with urea. Maize, however, responded when inorganic P sources were applied in combination with FYM or tithonia at this site. At Kakamega, maize responded to TSP but not to MPR or BPR when applied with urea. Application of TSP in combination with tithonia gave the highest maize yields at both sites. Of the tested technologies, only FYM when applied alone at Bukura was economically attractive.