Miracle-dz/UniFAR-FTUs huggingface dataset:
An overview and historical look back at the solvent extraction using nitrogen donor ligands to extract and separate An(III) from Ln(III)

The partitioning of minor trivalent actinides (An) from lanthanides (Ln) is one of the challenges in the chemical treatment of nuclear waste. The optimal ligand to carry out the separation of An(III) and Ln(III) using solvent extraction has to meet several important criteria: high selectivity towards the solute, chemical and radiolytic stability, stripping possibilities and recycling of the organic phase, high separation factors and good distribution ratio, to name just a few of them. A chronological line can be drawn along the development of each extraction ligand family and some milestones are emphasized in this overview. Further developments in organic synthesis of extracting ligands are expected.
Soybean root morphology in soils with and without tillage pans in the lower Mississippi river valley 1

Abstract During 1980, an extremely dry growing season, soybean (Glycine max L. Merrill) root morphologies were characterized at the R2 growth stage in Steele, Sharkey, Rilla, Calloway, and Stuttgart soils with a tillage pan and with a disrupted tillage pan. Results showed that the presence or absence of tillage pans resulted in dramatic changes in the soybean root morphology. Without pans, classical taproot systems tended to develop. With pans, soybean root systems tended to follow old root channels and fractures through the pan. Below the pan, soil structure manifested strong influences on root morphology. On all soils except the Steele (loamy sand), roots penetrated the tillage pan in numbers comparable to those penetrating the soil horizons with the pan disrupted. Although soil impedance to root penetration increases with drying and the 1980 growing season was exceptionally dry, mechanical impedance to soybean root penetration of tillage pans on silt loam and clay soils did not appear to be a problem.
Chemical Diversity of Lippia multiflora Essential Oils from West Africa

Abstract The essential oil content, composition and the physicochemical properties of Lippia multiflora leaves from twelve different regions in Ghana were characterized in this study. The Ghanaian oils showed a significant variability in their chemical composition and five chemotypes were identified. The oil from Aframso Bridge was yellow with a refractive index (RI) of 1.4853, density (DE) of 0.894 and was dominated by linalool (29%) and germacrene D (28%) with fresh, and slightly medicinal and spicy aroma. Ghanaian samples from Seikwa, Buem Nsuta and Golokwati were characterized by high levels of sesquiterpenes (45–70%). The aroma was medicinal/herbaceous and the color was typically yellow, except the oil from Seikwa which was dark orange-yellow, RI ranging from 1.4920 to 1.5043 and DE 0.893 to 0.93 D. The oils from Nyankpala, Sari, Amantin, Atebubu and Kobre contained high levels of aromatic monoterpenes (p-cymene 14–19%, thymol 30–40%, and thymyl acetate 14–17%). The oils were characterized as spicy and the color ranged from dark yellow (Nyankpala, Sari and Kobre) to yellow (Atebubu and Amantin) (RI 1.4969 to 1.5020, DE 0.9207 to 0.9344). The oil from Ho showed lower levels of aromatic monoterpenes and higher levels of farnesol, the oil was yellow and aroma woody/camphoraceous (1.492 RI, 0.893 D). In contrast, oils from Nsawkaw and Kofiase-Kubesiase were composed of high amounts of 1,8-cineole (43–47%), sabinene (12–15%, respectively), and were light yellow (RI 1.4695 to 1.4712, DE 0.8995 to 0.9002). A cluster analysis was performed for comparison and characterization of L. multiflora oils from Ghana other 33 oils from 10 African countries. The oils from Ghana with these five chemotypes appeared to be the most diverse oils in Sub-Saharan Africa.
New Biomedical Poly(urethane urea)−Layered Silicate Nanocomposites

Poly(urethane urea) segmented block copolymers [PUU] are used in a variety of biomedical applications,1 most prominently as blood sacs in ventricular assist devices and total artificial hearts. However, one of the principal drawbacks of these elastomers (particularly when used in completely implantable devices) is their relatively high permeability to air and water vapor. Conventional biomedical PUUs are comprised of ca. 80 wt % poly(tetramethylene oxide) [PTMO] soft segments, and it is the penetrant diffusion through this continuous polyether soft phase that gives rise to the high permeability. Several chemical approaches have been taken in an attempt to reduce PUU permeability, while maintaining the desirable biocompatibility and mechanical properties. One such approach has been to replace the PTMO with aliphatic polycarbonate soft segments.2 Alternatively, we recently described the synthesis and characterization of a series of polymers that have backbones chemically identical to the multiblock PUU, but which also possess polymeric combs of a material with superior barrier properties.3 Polyisobutylene (PIB) was chosen as the comb material due to the combination of its good barrier properties and its controllable (living cationic) polymerization. PIB incorporation varied between 2 and 30 wt %, with comb lengths ranging from ∼3000 to 29 000 g/mol. Water vapor and oxygen permeability were reduced by about a factor of 2 at the highest PIB contents,4 in line with what is expected from models assuming dispersed, spherical PIB microphases.5 The lack of precise control of the morphology of the PIB domains of these comb polymers limits further significant improvement in the permeability. In the past 5 years there has been intense interest in dispersing organically modified layered silicates (OMS) in polymers, particularly as mechanical reinforcement at low silicate loading levels.6-8 As a result of their high aspect ratio (often approaching 1000), the introduction of intercalated or exfoliated OMS inorganic layers in the polymer matrix can dramatically enhance the barrier properties at very low concentrations.9-11 In a natural extension of our earlier work on polyether-based PUUs, we have applied this nanocomposite approach to biomedical poly(urethane urea)s. In this note we describe our initial experiments on polymer/inorganic hybrids based on a generic PUU and an alkylammoniummodified montmorillonite, a biocompatible layered filler frequently used in cosmetics, food supplements, and stomach acid-reducing medicines.
Removal of metal ions from dilute solutions by sorptive flotation

Abstract The removal of soluble ionic species, such as toxic metal cations or oxyanions, from dilute aqueous solutions, as most waste waters are, was investigated in laboratory‐scale experiments (batch and continuous mode) by applying the sorptive flotation process. This method involves the preliminary abstraction or scavenging of metal ions using proper “sorbents”, which exist at the fine or ultrafine particle‐size range, followed by a subsequent flotation stage for the separation of metal‐loaded sorbent particles from the treated (cleaned) solution. The main flotation techniques for the generation of the necessary bubbles (dissolved air, dispersed, and electrolytic) were applied effectively. The examined sorbents for the initial stage of the process could be of either inorganic nature, conventional (powdered activated carbon and zeolites) or industrial solid byproducts originated in the mineral industry, or of a biological nature (biosorbents), such as those produced during fermentations, in sewage trea.
Synthesis and Antibacterial Studies of Chloramphenicol Loaded Nano-Silver against Salmonella typhi

Increase in bacterial resistance to most of conventional antibiotics has emerged as one of the most challenging problems for the researcher in the field of biomedical science and engineering. This therefore augers well to look for possible alternative antimicrobial agents that can overcome this resistance. Nanoparticles of metals and semiconductors have great potential as delivery agents in biology and medicine for carrying small molecules such as drugs, proteins, and genes. Metal nanoparticles combined with antibiotics may therefore show improved efficacy in specific treatment, thus lowering side effects associated with drug molecules. In the present study we report use of silver nanoparticles as an active carrier for drug; i.e., chloramphenicol (CHL) in polyvinylpyrrolidone (PVP). For the first time, it is shown that PVP can play a dual role in such studies wherein it acts as a stabilizing agent as well as a linker for binding the CHL to the silver nanoparticles. CHL-loaded silver nanoparticles showed a characteristic narrow SPR peak at about 410 nm, indicating the spherical nature of the monodispersed particles. The percentage loading of the drug onto the silver nanoparticles was found to be 81%. The drug-loaded silver nanoparticles showed substantially enhanced activity against clinically isolated S. typhi, thus showing considerable promise for further development. FTIR studies confirmed the binding of CHL to the silver nanoparticles through the −NH group of CHL and free −C = O group of PVP, thus confirming the role of PVP as a linker. The particle size distribution was found to be in the range of 10–15 nm. TEM indicated that the nanoparticles are spherical in shape. The drug-loaded silver nanoparticles were cast into film by using PVA, which showed a broadened XRD pattern, indicative of very small size.
Effect of processing on water absorption and softening kinetics in chickpea (Cicer arietinum L) seeds

The processing effect on the physical properties of chickpea seeds (kabuli type cv Athenas) is reported. Soaking of chickpea seeds in different solutions (distilled water, 0·5% NaHCO3 and 0·5% CaCl2) is characterised by a rapid water absorption followed by a decrease in the hydration rate to saturation point. An improvement in chickpea softening rate and water absorption during cooking, with previous 12 h soaking in 0·5% NaHCO3, was observed. The presence of Ca2+ ions delayed the softening process in chickpea seeds. Physicochemical changes associated to the soaking and cooking process necessary for reducing cooking time are discussed. The texturometer method was estimated as a suitable objective method for the evaluation of the cooking degree in chickpea seeds. © 1998 Society of Chemical Industry
Liquid-vapor interfaces of alkane oligomers: structure and thermodynamics from molecular dynamics simulations of chemically realistic models

Molecular dynamics simulations are used to predict the equilibrium liquid-vapor interface structure and surface tension of n-alkanes decane and eicosanes, C 10 H 22 and C 20 H 42 , respectively. The model treats each methyl and methylene group as one united Lennard-Jones atom. Realistic bond lengths, bond angle potentials, and torsional potentials are included in the simulation. The simulations predict that although the total mass density profile is monotonic, the density profile of the chain centers of mass and central segments is strongly peaked. The outer edge of the surface is dominated by chain ends
Rotational spectrum of the weakly bonded C6H6–H2S dimer and comparisons to C6H6–H2O dimer

Two symmetric-top,delta J = 1 progressions were observed for the C6H6–H2S dimer using a pulsed nozzle Fourier transform microwave spectrometer. The ground-state rotational constants for C6H6–H2S are B = 1168.53759(5) MHz, DJ = 1.4424(7) kHz and DJK = 13.634(2) kHz. The other state observed has a smaller B of 1140.580(1) MHz but requires a negative DJ = –13.80(5) kHz and higher order (H) terms to fit the data. Rotational spectra for the isotopomers C6H6–H234S, C6H6–H233S, C6H6–HDS, C6H6–D2S and 13CC5H6–H2S were also obtained. Except for the dimer with HDS, all other isotopomers gave two progressions like the most abundant isotopomer. Analysis of the ground-state data indicates that H2S is located on the C6 axis of the C6H6 with a c.m. (C6H6)–S distance of 3.818 A. The angle between the a axis of the dimer and the C2v axis of the H2S is determined to be 28.5°. The C6 axis of C6H6 is nearly coincident with a axis of the dimer. Stark measurements of the two states led to dipole moments of 1.14(2) D for the ground state and 0.96(6) D for the other state. A third progression was observed for C6H6–H2S which appear to have K0 lines split by several MHz, suggesting a nonzero projection of the internal rotation angular momentum of H2S on the dimer a axis. The observation of three different states suggests that the H2S is rotating in a nearly spherical potential leading to three internal rotor states, two of which have Mj = 0 and one having Mj = ±1,Mj being the projection of internal rotational angular momentum on to the a axis of the dimer. The nuclear quadrupole hyperfine constant of the 33S nucleus in the dimer is determined for the two symmetric-top progressions and they are –17.11 MHz for the ground state and –8.45 MHz for the other state, consistent with the assignment to two different internal-rotor states. The 17O quadrupole coupling constant for the two states of C6H6–H2O were measured for comparison and it turned out to be nearly the same in the ground and excited internal rotor state, –1.89 and –1.99 MHz, respectively. The rotational spectrum of the C6H6–H2S complex is very different from that of the C6H6–H2O complex. Model potential calculations predict small barriers of 227, 121, and 356 cm–1 for rotation about a, b and c axes of H2S, respectively, giving quantitative support for the experimental conclusion that H2S is effectively freely rotating in a nearly spherical potential. For the C6H6–H2O complex, the corresponding barriers are 365, 298 and 590 cm–1.
Development of Spectrophones for CW and Pulsed Radiation Sources.

Abstract : This technical report describes the construction of high sensitivity absorption measurement systems based on spectrophones (opto-acoustical cells) which have been developed for both CW and pulsed laser sources. These systems have been applied to measurements of absorption by atmospheric gases and particulates at IR laser frequencies. Construction, calibration, and linearity are discussed for a number of specific systems. Accurate measurements of absorption by atmospheric constituents in the so-called transmission 'window' frequency bands are required by both the DoD high-energy laser (HEL) and electro-optical sensor programs. Statistical predictions for system design and the development of real-time field measurement systems are both important possible applications of spectrophones of the type discussed in this report. High sensitivity is generally a requirement as a result of the relatively low absorption in the 'windows. ' (Author)
Squaraines as light-capturing materials in photovoltaic cells

Photovoltaic cells are considered to be one of the most promising renewable energy sources of the 21st century. In particular, dye-sensitized solar cells (DSSCs) and organic photovoltaic devices (OPVs) are potentially the most economical and environmentally friendly ones. Squaraine (SQ) has intense absorption at 600–850 nm, exactly where sun flux is the most abundant. Furthermore, various substituents on SQ cores provide great possibilities for different molecular-design strategies. These characters make SQs ideal candidates for new DSSCs and OPVs. In response to the rapid development of SQ-based solar cells, a panorama of these ongoing studies is presented here, including the general synthetic routes of SQs and the various SQs used in DSSCs and OPVs. Our discussions are focused on the diverse molecular designs of SQs used in DSSCs and OPVs. The design strategies to acquire better light-harvesting abilities are also provided here, as well as the principles behind these strategies.
Reactive Uptake of Ozone by Aerosol-Associated Unsaturated Fatty Acids: Kinetics, Mechanism, and Products

The heterogeneous reaction between ozone and oleic and linoleic acids, prevalent components of both marine and urban organic aerosol, were studied in a flow reactor using electron impact and chemical ionization mass spectrometry. Liquids and frozen liquids were used as proxies for atmospheric aerosol. The reactive uptake coefficients, γ, were determined to be (8.3 ± 0.2) × 10-4 and (1.2 ± 0.2) × 10-3 for liquid oleic and linoleic acid respectively and (5.2 ± 0.1) × 10-5 and (1.4 ± 0.1) × 10-4 for frozen oleic and linoleic acid, respectively. Although, the reacto-diffusive length is estimated to be rather small in the liquid experiments, <10 nm, a clear indication of the participation of subsurface layers in the uptake is observed. This is in contrast to uptake by the frozen acids where the reaction is limited to the surface. Aldehydes were identified as the major volatile reaction products: 1-nonanal was detected following reaction with oleic acid, 2-nonenal, 4-nonenal, and 1-hexanal were detected follow.
Effects of Long-Term Compost and Fertilizer Application on Soil Phosphorus Status Under Paddy Cropping System

Abstract External phosphorus (P) fertilization in intensive cropping systems often exceeds P demand by crops, which leads to P accumulation in soils. Levels of different pools of soil P have been affected not only by soil properties and climatic condition but also by rate and type of P applied. This experiment was conducted to investigate the long-term applications of compost and chemical fertilizer on soil phosphorus status in paddy cropping system after addition of compost and chemical fertilizers for 34 years in rice monoculture production at National Youngnam Agricultural Experiment Station, Miryang, Korea. Four different treatments of soil amendments were selected in this study: control, compost application, NPK (nitrogen–phosphorus–potassium) fertilizer application, and compost plus NPK fertilizer application. Phosphorus status varied with the long-term applications of compost and fertilizers, and the compost plus NPK fertilizer treatment significantly increased total P in soil. Available P was increased in the treatments that received chemical fertilizers. Applications of compost and chemical fertilizers increased organic P fraction but the ratio of organic P to total P declined with application of compost or chemical fertilizers. Phosphorus-fixation was significantly increased due to the long-term application of compost and chemical fertilizers. The P fixation was highest with iron (Fe) than with aluminum (Al) and calcium (Ca) in the paddy soil. The highest Fe-P content occurred in the compost plus NPK fertilizer treatment. These results represented that the higher level of P remaining in the soil is accumulated by long-term annual application of compost and chemical fertilizers than by that of chemical fertilizer, and P accumulation might be a gradual saturation of the P-sorption capacity.
Structural Studies of Rutile-Type Metal Dioxides

The structures of the four metal dioxides GeO2, SnO2, RuO2 and IrO2 (germanium, tin, ruthenium and iridium dioxides, respectively) have been redetermined by Rietveld refinement from neutron diffraction powder data. The four dioxides all adopt the rutile-type structure, space group P42/mnm (no. 136), with a = 4.4066 (1), 4.7374 (1), 4.4968 (2) and 4.5051 (3), c = 2.8619 (1), 3.1864 (1), 3.1049 (1) and 3.1586 (2) A, and x = 0.3060 (1), 0.3056 (1), 0.3053 (1) and 0.3077 (3), respectively. These results are compared with those for other metal dioxides that adopt the rutile structure and trends in structural and thermal vibrations for a series of 11 metal dioxides which adopt the rutile-type structure are described.
Requerimento hídrico e coeficiente de cultura da cana-de-açúcar irrigada no semiárido brasileiro

O objetivo deste trabalho foi determinar o requerimento hidrico e o coeficiente de cultura (Kc) da cana-de-acucar irrigada durante o ciclo de soca, variedade RB 92-579, na regiao semiarida do Submedio do Vale do Sao Francisco. O experimento foi conduzido em area de cultivo comercial de cana-de-acucar situada no municipio de Juazeiro, BA. Obteve-se o requerimento hidrico da cultura por meio do metodo do Balanco de Energia Razao de Bowen. Foram monitoradas tambem a biomassa acumulada e a fracao da radiacao fotossinteticamente ativa interceptada pela cultura (fRFA). Com os resultados constatou-se que a evapotranspiracao da cana-de-acucar atingiu uma taxa media diaria de 4,7 mm, em resposta ao acumulo de biomassa e, mas a fRFA apresentou, entretanto, influencia do tombamento da cultura durante a fase de crescimento maximo. O requerimento hidrico total da cana-de-acucar foi de 1710 mm, e o Kc atingiu o valor medio de 1,10 na fase de crescimento maximo. As equacoes de estimativa do Kc mensal, tendo graus dias acumulados e dias apos o corte como variaveis independentes apresentaram otimos ajustes (R2 ~ 0,95 e 0,98) e consideram a reducao nos valores de Kc devida ao tombamento da cultura.
Cathodoluminescence Studies of InGaN/GaN Multiple Quantum Well Structure Grown by Metal Organic Chemical Vapor Deposition

Scanning Electron Microscope (SEM) – Cathodoluminescence (CL) system is applied to InGaN/GaN Multiple Quantum Well (MQW) structure grown by Metal Organic Chemical Vapor Deposition (MOCVD). Emission from MQW and n-GaN layer beneath at various electron beam (EB) voltages show that MQW layer tends to have better luminescence efficiency grown on GaN layer with fewer defects. It is observed that areas with higher emission intensity always show a red shift in emission wavelength. It therefore indicates that high resolution CL system is able to image the Indium inhomogeneities formed during the epitaxial growth process in nanoscale.
Forward‐bias characteristics of Si bipolar junctions grown by molecular beam epitaxy at low temperatures

Forward‐bias current‐voltage characteristics of molecular beam epitaxy grown Si p+‐i‐n+ junctions have been determined at room temperature. At small widths of the i zone (Li=5 and 10 nm) band‐to‐band tunneling with a maximum peak‐to‐valley ratio of two is observed. Up to Li=30 nm (trap assisted) forward‐bias tunneling is apparent with saturation tunneling current densities somewhat lower than in p‐n junctions at comparable widths of the space‐charge region WSCR(0). For Li≳30 nm and Tg=500 °C growth temperature surface recombination dominates the low bias range. At Li=35 nm and Tg=325 °C, both surface and bulk recombination is observed. We found evidence that Si molecular beam epitaxy layers grown at this low temperature get an increasing density of crystalline defects with growing thickness.
ON THE APPROXIMATION OF SOLVENT EFFECTS ON THE CONFORMATION AND DYNAMICS OF CYCLOSPORIN A BY STOCHASTIC DYNAMICS SIMULATION TECHNIQUES

Abstract The molecular simulation technique of stochastic dynamics (SD) is tested by application to the immunosuppressive drug cyclosporin A (CPA). Two stochastic dynamics simulations are performed, one (SDCCl4 ) with atomic friction coefficients proportional to the viscosity of the nonpolar solvent CCl4, and one (SDH2O) with atomic friction coefficients corresponding to an aqueous solution. The atomic friction coefficients are also taken proportional to an approximate expression for the atomic accessible surface area. The properties of both stochastic dynamics simulations are compared to those of two full molecular dynamics (MD) simulations of cyclosporin A, one in a box with 591 CCl4 molecules, and one in a box with 632 H2O molecules. The properties of cyclosporin A as found in the molecular dynamics simulation in CCl4 are well reproduced by the SDCCl4 simulation. This indicates that the neglect of a mean force reresenting the average solvent effects on the solute is justified in the case of nonpolar so.