Miracle-dz/UniFAR-FTUs huggingface dataset:
Numerical Evaluation of Static‐Chamber Measurements of Soil—Atmosphere Gas Exchange: Identification of Physical Processes

The exchange of gases between soil and atmosphere is an important process that affects atmospheric chemistry and therefore climate. The static-chamber method is the most commonly used technique for estimating the rate of that exchange. We examined the method under hypothetical field conditions where diffusion was the only mechanism for gas transport and the atmosphere outside the chamber was maintained at a fixed concentration. Analytical and numerical solutions to the soil gas diffusion equation in one and three dimensions demonstrated that gas flux density to a static chamber deployed on the soil surface was less in magnitude than the ambient exchange rate in the absence of the chamber. This discrepancy, which increased with chamber deployment time and air-filled porosity of soil, is attributed to two physical factors: distortion of the soil gas concentration gradient (the magnitude was decreased in the vertical component and increased in the radial component) and the slow transport rate of diffusion relative to mixing within the chamber. Instantaneous flux density to a chamber decreased continuously with time; steepest decreases occurred so quickly following deployment and in response to such slight changes in mean chamber headspace concentration that they would likely go undetected by most field procedures. Adverse influences of these factors were reduced by mixing the chamber headspace, minimizing deployment time, maximizing the height and radius of the chamber, and pushing the rim of the chamber into the soil. Nonlinear models were superior to a linear regression model for estimating flux densities from mean headspace concentrations, suggesting that linearity of headspace concentration with time was not necessarily a good indicator of measurement accuracy.
Vented Explosion of Hydrogen-Air Mixtures in a Large Volume

Combustion experiments were carried out in a 2.3-m diameter spherical vessel with venting to the atmosphere over a hydrogen concentration range of6 to 20% by volume. Three vent sizes (15 em, 25 cm and 45 em) and three igniter locations (near-vent, centre and far-vent) were employed. The vents were initially covered with cardboard or aluminum foil that ruptured between I and 10 kPa. It was found that venting was effective in reducing the peak pressure at low hydrogen concentrations and for large vent areas for which the combustion times were much longer than the characteristic vent times. In all cases, central ignition led to the highest peak pressures and shortest combustion times, and near-vent ignition resulted in the lowest peak pressures and longest combustion times. Instabilities and turbulence caused by the vent opening resulted in enhanced burning rates. A simple one-dimensional model produced results in reasonable agreement with the experimental pressure transients when two burning rates (a lamina.
Factors Affecting the Stability of CdTe/CdS Solar Cells Deduced from Stress Tests at Elevated Temperature

CdTe/CdS solar cells were subjected to heat stress at 200 °C in the dark under different environments (in N2 and in air), and under illumination (in N2). We postulate that two independent mechanisms can explain degradation phenomena in these cells: i) Excessive Cu doping of CdS: Accumulation of Cu in the CdS with stress, in the presence of Cl, will increase the photoconductivity of CdS. With limited amounts of Cu in CdS, this does NOT affect the photovoltaic behavior, but explains the crossover of light/dark current–voltage (J–V) curves. Overdoping of CdS with Cu can be detrimental to cell performance by creating deep acceptor states, acting as recombination centers, and compensating donor states. Under illumination, the barrier to Cu cations at the cell junction is reduced, and, therefore, Cu accumulation in the CdS is enhanced. Recovery of light‐stress induced degradation in CdTe/CdS cells in the dark is explained by dissociation of the acceptor defects. ii) Back contact barrier: Oxidation of the CdTe back surface in O2/H2O‐containing environment to form an insulating oxide results in a back‐contact barrier. This barrier is expressed by a rollover in the J–V curve. Humidity is an important factor in air‐induced degradation, as it accelerates the oxide formation. Heat treatment in the dark in inert atmosphere can stabilize the cells against certain causes of degradation, by completing the back contact anneal.
Residual Effect of Malathion (Organophosphate) and Sevin (Carbamate) Application on Potato ( Solanum tuberosum )

An experiment was conducted at Shambat Agricultural farm to study the effect of pesticides residues on soil and potatoplant. Potato was planted on January, 2009 on ridges with a spacing of 70 cm between rows and 10 cm between plants. Sevin and Malathion pesticides were added at different concentrations to evaluate their effect on the plant growth and soil. The measurement taken was plant height (cm), fresh and dry weight (gm), leaf area (cm2), pH, total nitrogen %, phosphorus (ppm), leaf number and size of tubers. The results revealed that both chemicals affected negatively the vegetative growth of potato and its yield. It was noticed that the yield was generally less due to the effect of the heavy clay soil of Shambat. Addition of Sevin increased the total soil nitrogen and reduced soil organic carbon while the reverse was noticed for Malathion. Both chemicals lowered soil pH, from alkaline to neutral or slightly alkaline. However, they increased soil salinity which in turn affected potato growth and yield.
Polymorphism of Isotactic Poly(Butene‐1)

The conditions for reliable preparation of bulk PB‐1 samples in form III were established. The crystal structure of solution‐prepared PB‐1 samples was measured by X‐ray diffraction as a function of solvent used, solution concentration, temperature of solution preparation, and solvent evaporation or solution precipitation. Measurements at higher temperatures revealed the crystallization of form III to I at temperatures below 95°C and to form II at temperatures above 95°C.
Crystal Structures and Characterization of Ca9Fe(PO4)7and Ca9FeH0.9(PO4)7

Abstract Whitlockite-like compounds s- and o-Ca 9 Fe(PO 4 ) 7 and r-Ca 9 FeH 0.9 (PO 4 ) 7 were prepared and studied by XRD, IR, Mossbauer technique, and diffuse reflective spectroscopy. The crystal structures of the three phases were determined by the Rietveld analysis. The unit cell is hexagonal with a = 10.3391(2) A, c = 37.130(1) A, s-Ca 9 Fe(PO 4 ) 7 ; a = 10.3543(2) A, c = 37.168(1) A, r-Ca 9 FeH 0.9 (PO 4 ) 7 ; and a = 10.3406(2) A, c = 37.157(1) A, o-Ca 9 Fe(PO 4 ) 7 ; Z = 6; R 3 c space group. The redox reactions proceed reversibly without destruction of the crystal lattice in double calcium–iron phosphates and the oxygen stoichiometry is not variable. The introduction of hydrogen into the lattice causes a change of the P(1)–O(11) bond length and the formation of an O(11)–H … O(34) hydrogen bond. The redox reactions are accompanied by a position change of oxygen atoms O(24) and O(33). The main differences between the three phases are discussed on the basis of the crystal structures.
Two-Phase Shrinking Porous Media Drying: A Modeling Approach Including Liquid Pressure Gradients Effects

This article deals with the drying modeling of a saturated deformable porous media (solid + fluid). This modeling takes into account the mechanical behavior of the product as well as its initial conditions such as its moisture content and geometry. The effect of fluid pressure gradient on the fluid transfer is described by using Darcy's law, and the fluid compressibility is characterized by its bulk modulus of elasticity. The solid phase is supposed to be incompressible and the porous media permanently diphasic (ideal shrinkage hypothesis). The description of the strong thermo-hydro-mechanical coupling that takes place within the material during drying is taken into account in the light of Biot's consolidation theory by adopting Terzaghi's effective stress principle. The numerical resolution is performed by FEM and ALE methods. A comparison between experimental results (convective drying of an alumina gel) and numerical results improves the ability of this modeling to describe thermo-hydro-mechanical coupling. It further highlights a current lack of precision in the determination of the thermophysical parameters values that control the model.
Studies on the Ignition and Burning of Levitated Aluminum Particles

Abstract An experimental set-up is developed to investigate the burning of levitated aluminum particles ignited by a C02laser in air under high pressure conditions. Residence times of aluminum particles burning in the electrodynamic levitator are long enough to observe the total burning process, under normal and high pressures. Experiments allow to measure the ignition delay and the burning times of aluminum particles. These measurements and the accompanying high speed images give useful information on the burning processes of aluminum particles under various regimes. A numerical model is also developed to predict the burning rates of aluminum particles and the sizes of the alumina residues.
Thatch and Soil Characteristics of Cool- and Warm-Season Turfgrasses

Abstract Turfgrass thatch development is a direct consequence of an imbalance between growth and decomposition of organic residues. This study was conducted to determine the characteristics of thatch and the underlying soil in a three-year-old stand of Southshore creeping bentgrass (Agrostis palustris Huds.) and a six-year-old stand of Meyer zoysiagrass (Zoysia japonica Steud.). Intact thatch + soil cores were randomly collected from the two sites for thatch and soil bulk density and total porosity determinations. Disturbed samples of thatch and soil were processed and analyzed for total microbial biomass carbon (C); basal and specific maintenance respiration rates; total C, nitrogen (N) and hydrogen (H) contents; easily mineralizable, soluble, oxidizable and lignin C fractions, and organic matter quality. While the total microbial biomass C content and basal respiration rates were higher in thatches, the specific maintenance respiration rates were significantly lower in soils. Total, soluble, oxidizable and lignin C, and total N and H contents were significantly greater in thatches than in soils. Although the absolute amounts of soluble and oxidizable C contents were smaller in soil than in the thatch, the soluble and oxidizable C as fractions of total C were significantly lower in thatches than in soils. The bentgrass thatch contained more microbial biomass and lignin C than the zoysiagrass thatch. Both thatches had lower bulk densities and higher total porosities than the underlying soils. Spectrophotometric analyses suggested an accumulation of finer size organic matter in the bentgrass thatch than in the zoysiagrass thatch. An increase in microbial biomass and total C, but a substantial decrease in specific maintenance respiration rates, suggest that thatch development under turf may be acting as a C sink. A decline in microbial biomass and total C contents, but significant increases in specific maintenance respiration rates, suggest that soils under thatch may be serving as sources of CO2 to the troposphere. The effect was more pronounced at the zoysiagrass site than at the bentgrass site.
Preparation of HALS-Functional Core-Shell Nanoparticles and their Application in Poly(Butylene Terephthalate)

HALS-functional core-shell nanoparticles, poly(BA-MMA-PMPA), were prepared by emulsion polymerization. The chemical structure and the microstructure of the particles was confirmed by Fourier transformed infrared (FTIR) and transmission electron microscopy (TEM), respectively. The nanoparticles were used to modify PBT and had good compatibility with PBT. The mechanical properties before and after UV-irradiation analysis demonstrated that the UV-resistance and impact resistance of PBT were obviously improved by poly(BA-MMA-PMPA). The degradation degree of PBT was retarded by poly(BA-MMA-PMPA) as studied by thermogravimetry analysis (TGA). The surface chemical functional groups changes revealed that the surface of PBT was greatly protected by poly(BA-MMA-PMPA).
Sintering Model for Mixed‐Oxide‐Derived Lead Zirconate Titanate Ceramics

The properties of lead zirconate titanate (PZT) ceramics are determined by the microstructure and chemical homogeneity of Zr, Ti, and dopants within the grains as well as the presence of secondary grain boundary phases. Stoichiometric 53/47 PZT and compositions with 3 mol% PbO excess were prepared by the mixed-oxide process, and were densified by pressureless sintering in oxygen. The influence of PbO content and different La concentrations on the densification behavior was analyzed by dilatometric measurements. Quantitative image analysis showed a different relative density and grain size dependence for samples containing >0.5 mol% additives compared to samples with <0.5 mol% La. On the basis of a model experiment and by using different analytical methods (microprobe analysis, HRTEM, STEM, and Auger spectroscopy) three types of inhomogeneities could be detected in conventionally prepared PZT ceramics: the existence of Ti and La enrichment in the core of PZT grains, and PbO-rich secondary phases in triple junctions as well as in grain boundary films. The results of the microstructural characterization and the analysis of the densification behavior were finally combined to deduce a sintering model based on a Pb-vacancy concentration gradient within the PZT grains.
Comparative Antibacterial, Chemical and Morphological Study of Essential Oils of Thymbra spicata var. spicata Leaves by Solvent-Free Microwave Extraction and Hydro-Distillation

The essential oils of Thymbra spicata var. spicata were obtained by both hydrodistillation and solvent-free microwave extraction methods. Chemical composition and antibacterial activity of the essential oils were examined. The main constituents of both essential oils obtained by solvent-free microwave extraction and hydrodistillation from Thymbra spicata var. spicata were carvacrol (44.8–36.1%), γ-terpinene (23.8–26.1%), and p-cymene (7.3–9.6%), respectively. The essential oil obtained from solvent-free microwave extraction contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than hydrodistillation. The antibacterial activities of the essential oils from solvent-free microwave extraction and hydrodistillation were evaluated by the disc diffusion method against six bacterial strains. The essential oil extracted by solvent-free microwave extraction was more effective than the essential oil extracted by hydrodistillation against the tested bacteria except for E. coli ATCC 25922- and S. aureus ATCC 25923+. Especially, S. aureus ATCC 25923+ was more sensitive against the essential oils obtained from Thymbra spicata var. spicata. Scanning electron microscopy measurements show that glands (that are filled with essential oils) were subjected to more severe thermal stresses and localized high pressure by microwave heating, the pressure build up within the glands could have exceeded their capacity for expansion and break down of cell walls. Solvent-free microwave extraction resulted in more extract release more rapidly than in hydrodestillation.
Mixing of Particulate Material Studied by near Infrared Spectroscopy

This study aimed to characterise by near infrared (NIR) spectroscopy the physical parameters that are relevant to the quality of a pharmaceutical blend, such as mean particle size of a granular material, incompatibilities between particle size of the blend components and segregation tendencies. Binary blends consisting of granulated material (96% m/m) and an active pharmaceutical ingredient (API) (4% m/m) were prepared. Granule particle size was studied using the Kubelka–Munk function. In addition, NIR spectroscopy was applied for the monitoring of the API concentration during a blending step. Convection and diffusion phases were clearly identified.
Investigation of Reductive Dechlorination Supported by Natural Organic Carbon

Because remediation timeframes using monitored natural attenuation may span decades or even centuries at chlorinated solvent sites, new approaches are needed to assess the long‐term sustainability of reductive dechlorination in ground water systems. In this study, extraction procedures were used to investigate the mass of indigenous organic carbon in aquifer sediment, and experiments were conducted to determine if the extracted carbon could support reductive dechlorination of chloroethenes. Aquifer sediment cores were collected from a site without an anthropogenic source of organic carbon where organic carbon varied from 0.02% to 0.12%. Single extraction results showed that 1% to 28% of sediment‐associated organic carbon and 2% to 36% of the soft carbon were removed depending on nature and concentration of the extracting solution (Nanopure water; 0.1%, 0.5%, and 1.0% sodium pyrophosphate; and 0.5 N sodium hydroxide). Soft carbon is defined as organic carbon oxidized with potassium persulfate and is assumed to serve as a source of biodegradable carbon within the aquifer. Biodegradability studies demonstrated that 20% to 40% of extracted organic carbon was biodegraded aerobically and anaerobically by soil microorganisms in relatively brief tests (45 d). A five‐step extraction procedure consisting of 0.1% pyrophosphate and base solutions was investigated to quantify bioavailable organic carbon. Using the extracted carbon as the sole electron donor source, tetrachloroethene was transformed to cis‐1,2‐dichloroethene and vinyl chloride in anaerobic enrichment culture experiments. Hydrogen gas was produced at levels necessary to sustain reductive dechlorination (>1 nM).
Theoretical Studies of the Structure, Tautomerism, and Vibrational Spectra of 3-Amino-5-nitro-1,2,4-triazole

The structure, tautomerism, and vibrational spectra of the highly explosive 3-amino-5-nitro-1,2,4-triazole (ANTA) molecule were studied by ab initio molecular orbital calculations at the Hartree−Fock and second-order (MP2) and fourth-order (MP4) Moller−Plesset levels and by density functional theory (DFT) both in gas phase and in solution. It was found that in the gas phase the most stable tautomer is 2H-ANTA (3-amino-5-nitro-1,2,4-2H-triazole) at the HF level, while at MP2, MP4, and DFT levels the most stable tautomer is 1H-ANTA (3-amino-5-nitro-1,2,4-1H-triazole). For the 2H-ANTA tautomer, the calculated MP2 and DFT structures agree well with the experimental X-ray structures, but with the twisting of the nitro and amino groups much larger than in the solid state. The predicted IR spectra are given for all tautomers. The calculated fundamental vibrational frequencies at the DFT level generally compare well with the MP2 results. In the case of 2H-ANTA, the C−NO2, C−NH2, and N−H bond dissociation energies.
Reactions of oxygen with ZnO–101̄0‐surfaces

Investigations are reported on the reaction of oxygen with electrostatic neutral ZnO–1010‐surfaces studied by means of AES, LEED, EPR, thermal desorption spectroscopy, and isotopic exchange as well as changes in the surface conductivity and work function. Geometric and electronic structures of the surface are discussed. Reversible physisorption data are determined in the range of 120–250 K (ϑ<10−1 for P<10−4 Pa), from which adsorption isotherms and isosteric heats of adsorption are derived. Chemisorption is found in the range of 300–650 K (ϑ<2.5×10−4) on crystals with negligible amount of point defects at the surface. The energy of chemisorption and reaction rates can be described quantitatively by electron transfer models. Desorption rates for zinc and oxygen are derived from measurements of instationary crystal sublimation, the latter being strongly dependent on thermodynamically stable concentrations of oxygen vacancies at the surface, which can be determined quantitatively and removed during reaction.
Holistic study of space weather and space climate: 1700- 2018

We present an update of changes in space weather/space climate at Earth orbit using sunspot number (SSN) timeline (1700-2018), geomagnetic indices aa/Ap (1870–2018), solar polar magnetic field (1976-2017), interplanetary magnetic field (IMF) and galactic cosmic ray (GCR) flux (1963-2018) in the stratosphere at high latitudes. The Cycle 24 is close to minimum, expected in 2020. The baseline of aa index increases monotonically from 1900 to 1986 declining steeply afterwards, solar polar magnetic field decreases systematically for last three cycles (22–24) as do SSNs at cycle peaks. Livingston and Penn (2009) note a long term weakening of maximum magnetic field in sunspots since 1992. They expect SSNs for the Cycle 25 to peak at 7 (a steep decline in solar activity) leading to Maunder-like minimum, in contrast to prediction of a Dalton minimum by several colleagues. The North-South asymmetry in the solar polar field is pronounced for the decay phase of cycles 23, 24, it seems to change sign after the Cycle 21. GCR flux in the stratosphere is higher than in 1965 and increasing, pointing to an enhanced radiation exposure in future for passengers on transpolar flights, the astronauts on the space station as well as those travelling to and staying on the Moon and the Mars on prolonged missions; the assets in space would have to be hardened for safety from enhanced radiation.
Improved Detection of Hg2+ in Aqueous Solution with High Sensitivity and Selectivity by Using Mercury-Specific DNA, Sybr Green I and Gold Nanoparticles

We report a label-free, fast, fluorescence turn on assay for Hg2+ detecton by using mercury-specific DNA (MSD), Sybr Green I (SG) and gold nanoparticles (AuNPs). SG efficiently discriminates MSD and MSD/Hg2+ complex. The addition of gold nanoparticle decreases the background fluorescence signal further for MSD. The fluorescence intensity of MSD/Hg2+ complex keeps constant after addition of AuNPs. This property improves the signal-to-background ratio and decreases the detection limitation further. In addition, the method shows improved selectivity compared with that in the absence of AuNPs. This strategy could be applied to the detection of potassium ions and showed good generality.
The Significant Contribution Of Indonesian Human Capital To The Economic Growth

This study examines the contribution of human capital to Indonesia’sproductivity. The result of this study reveals a significant contribution ofhuman capital as shown in the model which is using highest weightedof primary and secondary level of education. The most significant resultfound in the model using secondary level as the highest weightedof human capital. In contrast, there is no significant contribution ofhuman capital using proportional weighted between education levels.This suggests that improvement in knowledge, adoption of technologyand skill in the primary and secondary education meet the demandof industries in Indonesia. This study uses a time series regression toanalyze data 1985-2010. DOI : https://doi.org/10.21632/irjbs.4. 1.49-57 Keywords: Human Capital, Education, Time Series Regression
Morphology of polysorbate 80 (Tween 80) micelles in aqueous 1,4-dioxane solutions

The structures of micelles of the surfactant polysorbate 80 (Tween 80) in 0–50% aqueous 1,4-dioxane solutions (pH 7.2, ionic strength 2.44 mM) were investigated by means of small-angle X-ray scattering. At 1,4-dioxane concentrations of 0–20%, core–shell cylindrical micelles formed because the crown-shaped polysorbate 80 molecules aggregated into a cylindrical layer of four chains entangled with one another through intra- and intermolecular interactions. At 30–40% 1,4-dioxane, core–shell discus micelles formed, and at 50% 1,4-dioxane, core–shell elliptic discus micelles formed by the same mechanism. By changing the 1,4-dioxane solvent concentration and increasing the solvent hydrophobicity, the micelles first change from core–shell cylindrical to core–shell discus and then from core–shell discus to core–shell elliptic discus micelles.