Miracle-dz/UniFAR-FTUs huggingface dataset:
Theoretical study of rare earth point defects in GaN

The behavior of rare earth dopants in GaN was investigated by means of theoretical techniques. The Density Functional based Tight-Binding method (DFTB) has been extended to include orbital dependent potentials (LDA+U and SIC-like) in attempt to model. the 4f states of lanthanide impurities within a realistic crystal model. We present results of an investigation into the structural and and energetic Properties of rare earth (Eu, Er and Tm) point defects in GaN. Lanthanide ions (either isolated or complexed with GaN native defects) prefer the Ga-site. Among the investigated defects the REGa V-N pairs are the most promising candidates as luminescent centers, while, interstitial lauthanides are found not to be compatible with the observed luminescence. Differences in the behavior of the single lanthanide ions are explained in term of different 4f-shell occupation and ion size.
The Pulse Survey An Assessment of the Student Recognition Culture in Schools

Students need to be recognized in their schools. This seems to be a self-evident assertion. Yet, what “recognition” is, how students experience it, and what the effects of different kinds of recognition are on student motivation and school success are questions with surprisingly complex answers. And although there are warehouses full of research studies on “school climate,” surprisingly little of that research deals specifically with recognition.
Green Manuring in Crop Production

ABSTRACT The positive role of green manuring in crop production has been known since ancient time. Importance of this soil ameliorating practice is increasing in recent years because of high cost of chemical fertilizers, increased risk of environmental pollution, and need of sustainable cropping systems. Green manuring can improve soil physical, chemical, and biological properties and consequently crop yields. Furthermore, potential benefits of green manuring are reduced nitrate (NO3 −) leaching risk and lower fertilizer N requirements for succeeding crops. However, its influence may vary from soil to soil, crop to crop, environmental variables, type of green manure crop used, and its management. Beneficial effects of green manuring in crop production should not be evaluated in isolation; however, in integration with chemical fertilizers. The objective of this article is to review recent advances in green manuring practice, in the context of potential benefits and drawbacks in use of this practice for annual crop production and sustain soil health and fertility.
Prediction of Glass Transition Temperatures for Polystyrenes by a Four‐Descriptors QSPR Model

A set of new molecular descriptors, R SC , S MC , D HB and M PE , which are obtained directly from polystyrenes monomer structures, are used to predict the Tg values of polystyrenes and generate a QSPR model by multiple linear stepwise regression analysis, with R = 0.959 and s = 15.20 K. Compared with the existing QSPR models, the proposed model requires only four descriptors, which can be obtained by simple calculation and makes it more valuable to predict the T g values of polymers.
Radiolysis of Aqueous Solutions Highly Enriched in O18

Solutions of H2O216,16 in water highly enriched in O18 were irradiated with x rays and protons. The effects of H2O2 concentration, pH, bromide and nitrite ions, on the yield of the isotopic species H2O216,18 and H2O218,18, were investigated. The ``molecular'' H2O2 is formed with a G value of 0.3 in neutral solutions. The formation of H2O216,18 is attributed to the attack of O18H radicals on H2O216,16. The evolved O216,18 may be regarded as a product of a parallel reaction. The yield of O216,18 is dependent on an exchange reaction between HO2 and H2O2. Specific effects due to added NO2— and high concentrations of Br— are discussed.
Military Camping Impacts on Vegetation and Soils of the Ozark Plateau

Abstract The woody vegetation and soils on 20-40-year-old military campsites were compared with undisturbed but otherwise similar areas in south-central Missouri. Military camping caused a reduction in the density and species richness of overstory and understory plants. Ground cover on the campsites is characterized by less litter and more bare ground, but overstory cover on the campsites was indistinguishable from the control sites. Overstory radial growth was unaffected by 40 years of military camping. Altered soil conditions on the campsite included higher bulk density, less total organic carbon and a trend toward lower infiltration rates. The percentage rock volume on the surface of the campsites suggests that between 28 to 61 cm of soil has been lost. Management options are presented in light of this research.
ADSORPTION OF DYFONATE (O-ETHYL-S-PHENYL ETHYLPHOSPHONODITHIOATE) ON HUMIC ACID

The adsorption of Dyfonate (O-ethyl-S-phenyl ethylphosphonodithioate) was studied on humic acid (HA) saturated with various cations (Fe3+, Al3+, Cu2+, Zn2+, Co2+, Mn2+, Ni2+, Ca2+, Mg2+, and H+). The amount of Dyfonate adsorbed was affected by the cation with which the HA was saturated. The adsorption process could be described empirically by a Freundlich-type isotherm. The K and constants of the Freundlich equation decreased and increased, respectively, with increase in temperature. The data suggest a physical type of adsorption.
Extraction of El-Lajjun Oil Shale

Abstract Extraction of the bitumen fraction of El-Lajjun oil shale was carried out using 17 different solvents, pure and combined. Out of all the solvents used, toluene and chloroform were found to be the most efficient for extraction of the bitumen to perform the major part of the experiments. This selectivity was based on the quality and quantity of the yield and on the quantity of solvent recovered. Extraction was carried out using a Soxhlet extractor. For complete recovery of solvent the extract phase was subjected to two stages of distillation, simple distillation followed by fractional distillation, where different cuts of oil were obtained. It was found that an optimum shale size of 1.0 mm offered better solvent recovery. One hour was the optimum time needed for complete extraction. The yield of oil was determined from the material balance gained from fractional distillation after testing for the existence of any traces of solvent trapped in the different cuts by using a gas chromotography techniqu.
Influence of Ester and Ether Groups on Solution Properties of Polyurethanes

Viscometric data in non-theta solvent were utilized for determination of the poly(ester-urethane)s and poly(ether urethane)s conformational transitions and of the unperturbed dimensions. The influence of soft and hard segments was observed for poly(ester-urethane)s. The samples with 2,4-tolylene diisocyanate in hard segments have smaller unperturbed dimensions compared with the samples containing 4,4′-methylene diphenylene diisocyanate, which are believed to possess significant chain rigidity. The crosslinking tendency in synthesis of polyurethanes with ether groups - by reaction of chain end -NCO in prepolymer with the hydrogen from -NHCOO-groups - and in solutions explains the anomalies observed in solution properties.
Rheology and Molecular Weight Changes during Enzymatic Degradation of a Water-Soluble Polymer

The rheological behavior and molecular weight characteristics of a natural polymer undergoing enzymatic hydrolysis were examined for aqueous guar solutions. Changes in weight-average molecular weight (Mw), deduced from gel permeation chromatography (GPC), were used to construct a kinetic model for the process, such that 1/Mw ∝ kt, with the rate constant, k, varying inversely with polymer concentration. This relationship suggests that enzymatic degradation was zeroth-order in guar concentration. These findings contrast with previous studies of natural polymer degradation which usually have interpreted the linear relationship between 1/M and time as first-order processes. Our analysis reveals that this linear relationship is expected regardless of the reaction order and that the true order can be determined only from the dependence of the degradation rate on initial polymer concentration. Rheological properties were sensitive to extent of degradation; several orders of magnitude change in zero shear viscosi.
Mössbauer spectroscopy on superparamagnetic nanoparticles used as catalyst supports for the production of fine chemicals

Temperature and field dependent Mossbauer spectroscopy has been used to characterize silica coated iron oxide nanoparticles with a core size of ~ 10 nm. Covalent attachment of oxodiperoxo molybdenum complexes to the silica surface of these particles yields an organic-inorganic hybrid nanocatalyst which is an active, magnetically separable epoxidation catalyst. Mossbauer spectroscopy identifies superparamagnetic γ-Fe2O3 particles, whereas the presence of significant amounts of Fe3O4 (≥ 5 %) can be excluded.
Online Cognitive Behavioral Therapy: An e-Mental Health Approach to Depression and Anxiety

This book aims to provide clinicians with information on the design and delivery of online cognitive behavioural therapy (CBT) interventions for depression and anxiety. Chapter 1 begins with a brief overview of the current problems with the availability of treatments for common mental health problems, including some of the cultural and financial barriers to accessing care, as well as issues with the insufficient, and inefficient, distribution of funding for mental healthcare. It outlines why the online delivery of therapy interventions may offer a range of benefits that may help to address these issues, and concludes with a brief summary of depression and generalized anxiety disorder (GAD), which are the focus of later chapters. Chapter 2 provides guidance on designing online treatment modules, both in terms of content and how it is presented. The authors also offer guidance on delivering feedback as a therapist. The remainder of the book (chapters 3–14) then presents the content of a 12-module CBT intervention for depression and GAD used by the authors. The book provides a good rationale for using online CBT programmes and the potential benefits this can have regarding access to treatment. The suggestions made for designing treatment modules are sensible, and there is a good focus on ways to build and maintain the therapeutic relationship online. While the module content presented will already be well known by CBT practitioners, the example messages from fictional clients are good, and the book encourages readers to write in their own responses, before presenting example responses from the therapist. This helps the reader to understand how the therapist and client communicate and work through treatment via this medium. The reader may be expecting an overview of online CBT as a whole, so it should be emphasized that as the subtitle suggests, the book is outlining a single approach, which is helpful and interesting but at times can give the book a rather narrow and prescriptive feel. A rationale for the order of the 12 modules is not provided, and I would have liked to see discussion of whether and how the choice and order of modules could be tailored to the client, which is done in various other online programmes to increase efficiency and minimize drop-out. The authors state that they hope the book will allow clinicians to develop their own online interventions, although this may be difficult based solely on the information presented, which does not cover broader topics in the field, such as the extent and nature of therapist guidance, data security, or the monitoring and empirical evaluation of clinical outcomes. Overall, although the scope of the book is limited, it does provide a helpful overview of why there is a role for online CBT interventions, and key principles of designing online therapy content. It may therefore be of use to those seeking a brief introduction to the topic, and an example of how the basic CBT principles and techniques might be presented in an online format.
Effect of particle size and drying temperature on drying rate and oil extracted yields of Buccholzia coriacea (MVAN) and Butyrospermum parkii ENGL

Summary The effect of particle size and drying temperature on drying rate and oil extracted yields of Buccholzia coriacea (MVAN) and Butyrospermum parkii (ENGL) was investigated. Air drying studies carried out on B. coriacea and B. parkii, tropical food sources subject to high post-harvest losses, have resulted in the establishment of a significant difference between oil yields extracted from samples of various particle size pretreatments (paste, 4 mm, 8 mm and whole kernels) dried at 45 and 60 � C with the highest oil yield given by the 4 mm thick slices dried at 45 � C. The influence of temperature and particle thickness on the drying rate has been evaluated. The drying constants were found to depend on both temperature and particle thickness. Analysis of the oil extracted from the 4 mm thick slices dried at 45 � C showed that apart from the acid value (52.4%), the saponification (181.2 mg g )1 KOH), peroxide (8.6 meq kg )1 ) and the unsaponifiable (7.43%) matter values of the extracted shea butter remain within the limits cited in the literature while a close analysis of the cake suggests that it could be a good mineral source.
Macro-element absorption at maturity in relation to grain yield in high-yielding rice cultivars

Abstract By applying nitrogen (N) and phosphorus (P) fertilizers at different rates and times to high-yielding rice cultivars, we determined the absorption of N, P, and potassium (K) in relation to the grain yield. The results showed that, at a higher top-dressing rate of N, the grain yield increased and the absorption of N, P, and K was stimulated, whereas top-dressing of P did not significantly increase the grain yield and nutrient absorption. The absorption of N, P, and K differed markedly among the cultivars, even at the same level of grain yield in the same field (for Yangdao 4 and Suweon 258). N absorption in line 9004 was 29.2 g m−2 for a paddy grain yield of 1,250 g m−2 (brown rice: about 1,000 g m−2), being much higher than the value reported in the literature. The ratio of N : P : K absorption at different yield levels revealed that, with the increase of grain yield of the cultivars, the absorption of P and K relative to the absorption of N decreased. The absorption amounts and ratios of N, P, and K depended on the cultivars, yield levels~, and possibly, soils of the field.
Two-Phonon Combination Raman Modes in Covalently Functionalized Single-Wall Carbon Nanotubes

Single-wall carbon nanotubes covalently functionalized with chloro-phenyl groups were investigated by Raman spectroscopy. We examine the features observed in the spectral ranges 350−1200, 1650−2000, and 2400−3200 cm−1. The Raman modes associated with the presence of defects, strongly enhanced by the functionalization are clearly distinguished from those defect independent. We indicate that some features highly enhanced by the electron−phonon coupling are very sensitive to charge transfers between the nanotubes and functional groups. A feature at ∼2900 cm−1 is observed in the spectra of functionalized nanotubes, and its origin is explained here as a combination of two disorder-induced modes.
Synthesis and Characterization of CdS Nanoparticles

CdS nanoparticles were synthesized by using PVP (polyvinylpyrrolidone) as macromolecular surfactant, N, N-dimethylformamide as solvent, cadmium acetate and thiourea as precursors. The optical properties and morphologies for the synthesized CdS nanoparticles were characterized by UV-Vis absorption spectroscopy and TEM (transmission electron microscopy) measurements. The results show that PVP could act as a better stabilizer for the formation of CdS nanoparticles in N, N-dimethylformamide. The obtained CdS nanoparticles have spherical morphology and a narrow size distribution. CdS nanoparticles could give an apparent extionic absorption peaks and quantum confinement effects.
Classical Heisenberg model of magnetic molecular ring clusters: Accurate approximants for correlation functions and susceptibility

We show that the measured magnetic susceptibility of molecular ring clusters can be accurately reproduced, for all but low temperatures T, by a classical Heisenberg model of N identical spins S on a ring that interact with isotropic nearest-neighbor interactions. While exact expressions for the two-spin correlation function, CN(n,T), and the zero-field magnetic susceptibility, χN(T), are known for the classical Heisenberg ring, their evaluation involves summing infinite series of modified spherical Bessel functions. By contrast, the formula CN(n,T)=(un+uN−n)/(1+uN), where u(K)=coth K−K−1 is the Langevin function and K=JS(S+1)/(kBT) is the nearest-neighbor dimensionless coupling constant, provides an excellent approximation if N⩾6 for the regime |K| 50 K, the associated.
Pentachlorophenol Sorption by Organo-Clays

Several clay organic complexes were prepared by placing organic cations on the exchange sites of smectite clays and studied as sorbents for pentachlorophenol (PCP). The organic cations used ranged from very hydrophobic in nature (e.g., dioctadecyldimethyl+ (DODMA+)- and hexadecyltrimethyl+ (HDTMA+)-ammonium) to those having minimal hydrophobic properties, such as tetramethylammonium+ (TMA+). In general, the more hydrophobic the cation on the smectite the greater the uptake of PCP from water. For the very hydrophobic clays (DODMA+- and HDTMA+-smectite) the uptake of PCP was via non-polar interactions between the alkyl (e.g., -C18) groups on the organic cation and PCP. In a mechanistic sense, this interaction appeared to be similar to a partitioning process between water and the organic phase of the clay-organic complex. The organic phases of DODMA+-smectite were about 10 times more effective than the organic matter of natural sediments for removing PCP from water. For those organo-clays containing small organic cations (e.g., TMA+), the organic phase consisted of separate small organic moieties, such as the methyl group. This phase did not act as an effective partitioning medium despite a significant carbon content, and very little PCP was taken up. Results from this study suggest the possibility of treating soils and subsurface materials with large hydrophobic organic cations to enhance the sorptive properties of these natural materials.
Anisotropic Surface Melting of an Ice Crystal and Its Relationship to Growth Forms

Surface structures of ice crystals are discussed on the basis of experiments and molecular dynamics simulation. Experimental results showed that anisotropic surface melting can occur on the {0001}- and {1010}- faces of an ice crystal at temperatures just below the bulk melting point. Molecular dynamics simulations of ice surfaces were also carried out in order to examine the dynamic properties of surface melting. Anisotropic temperature dependence on the thickness of the quasiliquid layer (qll), which was consistent with the experimental results, was confirmed between both the {0001}- and {1010}-faces. Self-diffusion coefficients, which were estimated from the translational movements of water molecules in the quasiliquid layer, indicate that the dynamic properties of the quasiliquid layer change significantly with changes in the depth from the qll surface. Finally, growth forms of ice crystals are discussed in connection with anisotropic surface melting.
The effect of intermolecular interactions on the electric properties of helium and argon. III. Quantum statistical calculations of the dielectric second virial coefficients

The second dielectric virial coefficients of helium and argon are investigated using a fully quantum statistical approach and recent accurate ab initio results for the interatomic potentials and the interaction-induced polarizabilities. We thereby extend a preceding investigation based on a semiclassical approach to include quantum effects. For helium the results support the findings of a previous study by Moszynski et al. [J. Chem. Phys. 247, 440 (1995)] that quantum effects are substantial for temperatures below 10 K, while they are practically negligible above 70 K. For argon special care is needed in the numerical integrations carried out in the quantum statistical calculation of the virial coefficients, due to the presence of quasibound states in the continuum and a slow convergence of the summation over the angular momentum. Here quantum effects are practically negligible in the range of temperatures experimentally investigated, i.e., between 243 and 408 K. As far as comparison with experimental data is concerned, large discrepancies are found for some of the low-temperature experimental measurements of helium. Agreement is also unsatisfactory for high temperatures for argon and experimental redetermination is suggested.
In Situ Water Vapor Measurements Using Coupled UV Fragment Fluorescence/Absorption Spectroscopy in Support of CRYSTAL-FACE

Understanding the coupling of dynamics, chemistry, and radiation within the context of the NASA Earth Science Enterprise (ESE) and the national Climate Change Science Program (CCSP) requires, as a first-order priority, high spatial resolution, high-accuracy observations of water in its various phases. Given the powerful diagnostic importance of the condensed phases of water for dynamics and the impact of phase changes in water on the radiation field, the accurate, in situ observation of water vapor is of central importance to CRYSTAL FACE (CF). This is clear both from the defined scientific objectives of the NRA and from developments in the coupled fields of stratosphere/troposphere exchange, cirrus cloud formation/removal and mechanisms for the distribution of water vapor in the middle/upper troposphere. Accordingly, we were funded under NASA Grant NAG5-11548 to perform the following tasks for the CF mission: 1. Prepare the water vapor instrument for integration into the WB57F and test flights scheduled for Spring 2002. 2. Calibrate and prepare the water vapor instrument for the Summer 2002 CF science flights based in Jacksonville, Florida. 3. Provide both science and engineering support for the above-mentioned efforts. 4. Analyze and interpret the CF data in collaboration with other mission scientists. 5. Attend the science workshop in Spring 2003. 6. Publish the data and analysis in peer-reviewed journals.
Electronic Structure of Quaternary Chalcogenide Ag 2 In 2 Ge(Si)S 6 Single Crystals and the Influence of Replacing Ge by Si: Experimental X-Ray Photoelectron Spectroscopy and X-Ray Diffraction Studies and Theoretical Calculations

Ag 2 In 2 GeS 6 and Ag 2 InSiS 6 are two interesting quaternary-sulfide single crystals. Starting from our previous investigation on Ag2In2GeS6 single crystals, the Ag2In2SiS6 is investigated here. We demonstrate the effect of replacing Ge by Si on the electronic structure and the bonding properties. We have used X-ray diffraction (XRD) data for Ag2In2Ge(Si)S6 single crystals as input to our theoretical calculations using the all-electron full potential linearized augmented plane wave method to solve the Kohn Sham Density Functional Theory (DFT) equations. As remarkable finding, our calculations show that, on replacing Ge by Si atom, the environment of the S atoms is changed significantly. The energy gap depends on the exchange correlation function. For the local density approximation (LDA) the energy gap is 0.76 eV, while, based on the modified Becke-Johnson approximation (mBJ), the energy gap increases to 1.98 eV. We should emphasize that this energy gap in Ag2In2SiS6 is almost the same as that obtained for Ag2In2GeS6 (1.96 eV). Another significant finding is that when we replace Ge by Si the conductions bands move away from the Fermi energy while the valence bands are almost unchanged. In order to support the theoretical calculation the calculated total density of states below EF (TDOS-VB) of Ag2In2SiS6 single crystals is compared with our experimentally measured valence-band X-ray photoelectron spectroscopy (XPS-VB). The theoretical spectrum reproduces the general features structure of the measured XPS-VB faithfully.