Miracle-dz/UniFAR-FTUs huggingface dataset:
The theory and measurement of partial discharge transients

A theoretical approach to partial discharge transients is presented. This approach is based on the relationship between the charge induced on the measurement electrode by those created in the interelectrode volume during partial discharge activity. The primary sources for these induced charges are the charges which, as a result of partial discharge activity, are distributed within the voids of the insulation medium. These charge relationships are derived, and their application to the measured transients associated with the time dependence of the induced charge is presented. The application to multiple electrode systems of practical interest is illustrated. A discussion of the salient features and practical aspects of the theory is included. >
Reaction mechanism and kinetics of aqueous solutions of 2-amino-2-methyl-1-propanol and carbon dioxide

The mechanism and kinetics of the reaction between aqueous solutions of CO 2 and a sterically hindered primary alkanolamine, 2-amino-2-methyl-1-propanol (AMP), were investigated at 278-298K by using a stopped flow technique. Experiments were also carried out with monoethanolamine (MEA) solution, which is the sterically unhindered form of AMP. The corresponding second-order rate constants at 298K were found to be 520 and 5545 m 3 /(kmol.s) for AMP and MEA with activation energies of 41.7 and 46.7 kJ/mol, respectively. On the basis of this rate constant, the reaction was considered to be formation of carbamate which subsequently hydrolyzed
Magnetic-field-induced enhancement of ion beam energy in a magnetically expanding plasma using permanent magnets

Ion energy distribution functions (IEDFs) near a source exit of a magnetically expanding argon plasma using only permanent magnets (PMs) are measured by a combination of a retarding field energy analyzer and a pulsed probe method for three types of magnetic-field configurations and various operating gas pressures, where the magnetic-field strength in the source tube is increased up to 270 G by adding the number of the PM layers. The 13.56 MHz rf power for plasma production is maintained at 250 W. The IEDFs show the existence of an accelerated group of ions. It is found that the energy of the accelerated ions increases when the magnetic-field strength is increased, but saturates at seven times the electron temperature at argon pressures of 0.6–1.6 mTorr. Our results show that the maximum velocity of the accelerated ions is found to be 14 km s−1 with a Mach number of 3.8.
On the Capability of the Generalized Gamma Function to Represent Spray Drop‐Size Distribution

The three‐parameter, Generalized Gamma function solution of a recent MEF formulation used to derive liquid spray drop‐size distribution, is applied to sprays resulting from three different atomization processes. The objectives of these applications are to determine the sign of the parameters for which this function reports a more reliable fit and to further understand the parameter stability problem reported elsewhere. It is found that the lack of stability of the parameters is related to a characteristic feature of the mathematical function and appears for a series of spray drop‐size distributions with constant shape. For each situation analyzed in the present study, the Generalized Gamma function provides a very good fit with parameters that are either constant or correlated to the working conditions. As far as the sign of the parameters is concerned, the results show that the best formulation is a function of the spray and that it is impossible to know, a priori, which parameter sign will report the best fit. Finally, for one situation, it is found that the Generalized Gamma function allows extrapolation of drop sizes outside the measured values. All of the results converge to conclude that the three‐parameter Generalized Gamma function, which is identical to the well‐known Nukiyama‐Tanasawa distribution, accumulates valuable attributes to represent liquid spray drop‐size distributions.
Ice Crystal Size Modifications during Frozen Beef Storage

Studies of ice recrystallization in frozen stored bovine meat were performed at −5°, −10°, −15°, and −20°C over a 5-month period. A histological technique of isothermal freeze-substitution was used. Experimental results showed the existence of a limit crystal diameter independent of temperature and initial diameter. A kinetic model for ice recrystallization based on the difference between the mean and the limit curvature of the system satisfactorily fitted the obtained data. An equation to predict theoretically the limit diameter—also applicable to other food systems—was proposed. Significant effects of thermal oscillation on ice crystal sizes were observed. Activation energy of recrystallization was related to protein denaturation and exudate production.
The Ecological Impact of Used Petrochemical Oils on Soil Properties with Special Reference to Physicochemical and Total Petroleum Hydrocarbon Contents of Soils around Automobile Repair Workshops

Abstract Soils around automobile repair workshops were analyzed for physicochemical, elemental, and hydrocarbon contents with a notion to assess the contamination level of the soils via petrochemicals mishandling. The soils were collected using standard analytical procedures, while their elemental contents were determined using bulk scientific atomic absorption spectrometry/atomic emission spectrometry techniques. Total petroleum hydrocarbons, which are known to be potential carcinogens and physicochemical parameters—pH, Cl−, CO3 2−, electrical conductivity, and organic matter contents—were determined using standard analytical techniques. Ten elements—Mn, Zn, K, Na, Cu, Fe, Ni, Cr, V, and Pb—were analyzed and detected and their concentrations, the enrichment factors, Pollution Index, and Geoaccumulation Index values were established. The concentrations of K, Mn, V, Cr, Ni, Pb, Zn, and Cu were higher in the oil-contaminated soils than those of other Nigerian soils, while the values of the physicochemical parameters (CO3 2−, Cl−, and electrical conductivity) followed the same trend. The results of the Geoaccumulation Index indicated that the soils were very heavily polluted with all the metals (Geoaccumulation Index values > 5), except V (4 < Igeo < 5) which heavily polluted and Pb (2 < Igeo < 3) which moderately polluted the soils. These results were corroborated by their values, which were excessive when compared with their tolerable limits. The total petroleum hydrocarbons of the soils were detected at high levels when compared with studies of similar settings. The overall results showed that the soils of the area were highly contaminated and might be detrimental to living existence.
CONTRACTION CHARAClFRlSTlCS OF MOLDED CERAMICS DURING DRYING

ABSTRACT The characteristics of drvine and contraction (shrinkage) of molded ceramics were expenmentally studied to clarify the effects of drying conditions on contraction behaviors or deformation during drying processes. Mikawa-Shanshu clay molded into spheres or slabs was used as a sample which underwent convective drying by hot air. Three periods of preheating, constanl rate and falling rate existed, and the contraction was observed mainly in the preheating and constanl rate periods for all samples. It is also observed that the behavior of ihe contraction of molded clay is inflienced significantly by drying conditions. The higher drying rate makes the contraction of clay more remarkable in the preheating and constant rate periods. This behavior could not be explained from the difference of the moisture content distribution among runs. However, it is suggested that the inside parts of molded ceramics may be subjected to the strong compressional stresses and the strain-stress in the sample would Influenc.
Biodiesel production by esterification /transesterification of jatropha oil over sulfated zircona

Transesterification of jatropha curcas oil (JCO) with high acidity (8.4%),using methanol over sulfated zirconia as heterogeneous acid catalyst was investigated. Sulfated zirconia was directly synthesized by solvent – free method (S-ZrO2) at 600°C for 5 h, and characterized by various physicochemical techniques. The surface areas and pore volume were 9.71716 m 2 /g and 5.20631x 10 -3 cm 3 /g respectively. This catalyst exhibits excellent activity in esterification / transesterification of (JCO). The alcoholysis conversion of JCO under optimized conditions (65°C,16 h , 1:40 MR oil to methanol and 12.5% wt of catalyst) was 92 . 33%. While under subcritical methanolysis (200°C, 21 bars) was 95.6% after 1h. Generally oils containing high level of FFA cannot be directly esterified using base catalysts currently employed. Kinetic data on the transesterification reaction were achieved by conducting the reaction at various reaction times, catalyst dose and molar ratio. The experimental data was interpreted with a 1 st order reaction. The reaction was represented fairly well by pseudo homogeneous 1 st order reaction and the kinetic parameters were obtained. A good agreement between the experimental data and the model were observed.
Measuring the effect of ionic liquids on laccase activity using a simple, parallel method

Laccase activity was measured in the presence of 63 water-miscible and water-immiscible ionic liquids, including imidazolium, pyridinium, quaternary ammonium and quaternary phosphonium salts. A simple, parallel method was used to determine activity. In general, water-immiscible ionic liquids, especially bis[(trifluoromethyl)sulfonyl]amide salts, supported the highest enzyme activities.
Experimental Investigation of Spray and Combustion Characteristics of Dimethyl Ether in a Common-Rail Diesel Engine

Various characteristics of dimethyl ether (DME) as an alternative fuel for compression ignition engines were experimentally investigated including its spray characteristics, combustion performance, and emission reduction in a common-rail diesel engine. The spray behavior of DME was analyzed in terms of injection rate, spray development, and spray tip penetration, which were measured by an injection rate meter and a high-pressure spray chamber equipped with a spray visualization system. In addition, the engine performance and indicated mean effective pressure (IMEP), as well as exhaust emissions, including oxides of nitrogen (NOx), soot, hydrocarbons, and carbon monoxide were measured at various injection and operating cycle parameters. The combustion characteristics of DME fuel were compared with those of conventional diesel fuel in a diesel engine. Experimental results show that DME has an injection delay 0.03 ms shorter and a maximum injection rate 21% higher than those of diesel fuel at a constant inje.
Solving the riddle of the intradiol and extradiol catechol dioxygenases: how do enzymes control hydroperoxide rearrangements?

Metallo-enzymes catalyse a rich variety of biochemical reactions, some of which have little or no precedent in laboratory chemistry. Studies of such enzyme-catalysed reactions have benefited greatly in recent years from the pace of new protein X-ray crystallographic structures, but a detailed understanding of enzyme-catalysed reactions at the molecular level has required an interplay between structural studies, mechanistic studies, and small molecule model studies. This article will describe recent studies on an intriguing and long-standing puzzle in mechanistic enzymology, that of the non-haem iron-dependent catechol dioxygenases.
Simple Rule-Based Algorithm for Optimizing Volatile Fatty Acids Production in Primary Sludge Fermentation Schemes

In this paper, a model-based algorithm for optimizing the primary sludge fermentation process design and operation is described and evaluated. This is a recently used method to obtain the volatile fatty acid (VFA), needed for the enhanced biological phosphorus removal process, directly from raw wastewater. The proposed algorithm consists of a heuristic reasoning algorithm based on the expert knowledge of the process. Only effluent VFA and the sludge blanket height have to be set as design criteria, and the optimization algorithm obtains the minimum return sludge and waste sludge flow rates which fulfill those design criteria. It has been evaluated by simulating different temperature and sludge volume index (SVI) influent conditions in order to evaluate the algorithm performance under different conditions, as well as its sensitivity with respect to temperature and SVI, which are the most important parameters in these systems. The same tendencies observed by simulation were observed afterward in pilot plant experiments.
Effect of Temperature on the Relative Densities of Essential Oils and Water

ABSTRACT The densities of essential oils from traditional herb and New Zealand native species were measured over the temperature range 20°-60°C. The density of all oils decreased as temperatures increased. There was some variation between oils in the temperature coefficients of the change in density. The density differentials between oil and water and their temperature coefficients varied markedly between the different oils. A preliminary separation coefficient is used to indicate the effect of oil density and condensate water viscosity on oil separation at different temperatures. Separation of less dense oils with small differentials (fennel) would benefit more from increased temperatures than less dense oils with large differentials (coriander). It is necessary to use both density and viscosity data to determine if temperature control of a separator will be required to obtain efficient separation of an oil from the condensate stream.
Effect of Asphaltenes on SHRP Superpave Specifications

The composition of an asphalt can greatly affect its physical and chemical properties. Increasing the asphaltene content creates an asphalt with superior high-temperature properties while having a minimum impact on the low-temperature properties. Increasing the saturate content improves the low-temperature properties but hurts the high-temperature properties as well. Hardening due to oxidation is dependent on the amount of both asphaltenes and saturates present. At low levels of asphaltenes, saturates help the hardening susceptibility. However, as levels of asphaltenes increase, an increased saturate level can greatly increase the hardening susceptibility.
Carbon attrition during the fluidized combustion of a coal

The generation of carbon fines by attrition during the fluidized combustion of a bituminous coal has been studied by means of a 140mm ID fluidized-bed combustor under variable excess air factor, bed temperature, fluidizing velocity and size of bed sand and coal. Results indicate that rates of attrited fines are roughly proportional to excess of gas velocity above the minimum for fluidization and bed carbon exposed surface. Attrition rate constant is affected by size of sand and, to a less extent, and particularly with finer coal, by bed temperature.
Removal of Dissolved Heavy Metals from Acid Rock Drainage Using Iron Metal

The chemical and microbial activity of corroding iron metal is examined in the acid rock drainage (ARD) resulting from pyrite oxidation to determine the effectiveness in neutralizing the ARD and reducing the load of dissolved heavy metals. ARD from Berkeley Pit, MT, is treated with iron in batch reactors and columns containing iron granules. Iron, in acidic solution, hydrolyzes water producing hydride and hydroxide ion resulting in a concomitant increase in pH and decrease in redox potential. The dissolved metals in ARD are removed by several mechanisms. Copper and cadmium cement onto the surface of the iron as zerovalent metals. Hydroxide forming metals such as aluminum, zinc, and nickel form complexes with iron and other metals precipitating from solution as the pH rises. Metalloids such as arsenic and antimony coprecipitate with iron. As metals precipitate from solution, various other mechanisms including coprecipitation, sorption, and ion exchange also enhance removal of metals from solution. Corrodin.
The swelling behavior of polyelectrolyte multilayers in air of different relative humidity and in water

The swelling properties of physisorbed polyelectrolyte multilayer self-assemblies with alternating polyion charge in humid air and in aqueous environment were investigated via X-ray and neutron reflectometry as well as optically, using surface plasmon spectroscopy. The sorption behavior was similar to that found for neutral polymers and was related to an internal screening of the charges of the adjacent layers owing to the high entanglement of the polyelectrolyte chains and the resulting low mobility of the polymer segments. The screening was found to be incomplete only in the top layer, resulting in a net charged surface.
Toward the construction of parameter‐free doubly hybrid density functionals

Doubly hybrid (DH) functionals present a new class of density functionals, which enfold the nonlocal orbital-dependent components not only in the exchange part but also in the correlation part. Different types of DH functionals have been proposed according to different philosophies. DH functionals are shown to better fulfill certain physical conditions such as the linearity condition for fractional charges than other conventional functionals, which accounts for the generally improved performances of DH functionals in the description of thermochemistry and thermochemical kinetics for the main group chemistry. Efforts shall be made toward the construction of parameter-free DH functionals and the proper description of the dissociation limit with strong static correlation. The latter is related to the fractional spin errors, the reduction of which is important for secure applications in transition metal chemistry. © 2014 Wiley Periodicals, Inc.
Water desorption and thermodynamic properties of okra seeds.

The objective of the present work was to determine desorption isotherms of okra seeds for diverse conditions of temperature (10°C to 50°C) and relative humidity (0.11 to 0.96) of the air, as well as determine the values of isosteric heat of desorption, differential entropy, and Gibbs free energy. To obtain the equilibrium moisture content, a static method was used. Experimental data were adjusted to frequently used mathematical models for representation of hygroscopicity of agricultural products. Calculation of the net isosteric heat of desorption was performed based on the Clausius-Clapeyron thermodynamic relation. From the obtained results, it was concluded that equilibrium moisture content of the okra seeds decreased with an increase in temperature at the same relative humidity, as is the case of the majority of agricultural products. Based on statistical parameters, the Chung-Pfost model best represented the hygroscopicity of the okra seeds. Values of the integral isosteric heat of desorption as well as the differential entropy and Gibbs free energy for the okra seeds decreased with an increase in moisture content.
Effect of temperature on the conformation of lysozyme adsorbed to silica particles

Steady-state and lifetime fluorescence spectroscopy was used to study the conformation of hen egg white lysozyme adsorbed to differently charged colloidal silica particles as a function of temperature. While electrostatic interactions appear to be the driving force for adsorption, a decreased charge density of the substrate was found to enhance attractive protein–silica interactions. In the adsorbed state the temperature of unfolding is lowered by about 12–20°C, reflecting a decreased thermal protein stability. Applying a two-state thermodynamic model significantly smaller enthalpy and entropy changes have been found for the temperature-induced unfolding of lysozyme when it is adsorbed to the silica particles. From intrinsic fluorescence lifetime measurements a characteristic change of the lifetime distribution of lysozyme due to adsorption has been observed over a wide temperature range. These results were found to be consistent with an adsorption-induced modification of the lysozyme structure and a spreading of lysozyme on the silica particles in the process of unfolding.
Treatment of wood with aminofunctional silanes for protection against wood destroying fungi

Abstract Different aminofunctional silanes were tested for their suitability to preserve wood against basidiomycetes in a mini-block experiment according to EN 113. High effectiveness against the brown rot fungus Coniophora puteana was maintained over prolonged exposure times of up to 18 weeks. Resistance against the white rot fungus Trametes versicolor was only enhanced in the initial phase of exposure (6 weeks); after longer exposure times of 18 weeks, considerable mass losses were observed. It was shown that the antifungal resistance was caused by the amino groups of the oligomeric silane systems, while alkyl groups, which influence the water uptake of wood, only had a minor impact. For effective protection, acidic conditions of the treatment solution were important; this promotes the formation of cationised amino groups (ammonium). The silane quaternary ammonium compound (Si-QAC) 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride was applied in combination with an oligomeric silane system to incorporate quaternary ammonium sites into a SiO2 matrix via a sol-gel process. This combined treatment significantly enhanced the decay resistance of pine wood against C. puteana.
Oxidation of flooded mine tailings due to resuspension

Laboratory experiments were performed to assess the contribution of resuspension to the oxidation of pyrrhotite mine tailings flooded with a shallow water cover (up to 80 cm). Resuspension was produced by a paddle rotated at prescribed speeds in the water cover. The quality of the water cover was monitored over a 126 day period and the results were compared to the case where the tailings were kept still (no resuspension). The results showed that resuspended tailings oxidized considerably more than tailings at rest. The pH and dissolved oxygen concentration of the stirred water covers were 2.6 and 14 times lower, respectively, than those of the static water covers where there was no resuspension. Sulphate production increased by about 26-64 times, while the release of metals such as zinc, copper, and nickel was 1020, 318, and 138 times greater, respectively. The suspended tailings were finer and had lower pyrrhotite content at the end of the experiments than the tailings at rest and the original tailings.