Miracle-dz/UniFAR-FTUs huggingface dataset:
Computational Investigation of FeS2 Surfaces and Prediction of Effects of Sulfur Environment on Stabilities

Density functional theory calculations were employed to investigate the (001), (210), (111), and (110) surfaces of FeS2. The surface free energies were calculated in equilibrium with a sulfur environment using first-principles based thermodynamics approach. Surfaces that feature metal atoms in their outermost layer are predicted to be higher in energy. Within the studied subset of (1 × 1) terminations, the stoichiometric (001) surface terminated by a layer of sulfur atoms is the most stable for sulfur-lean condition. For increasingly sulfur-rich environment, two structures were found to have notably lower surface energies compared to others. They have (210) and (111) orientation, both terminated by layers of sulfur. Interestingly, these surfaces are nonstoichiometric exhibiting an excess of sulfur atoms.
Aqueous Two-Phase Flotation for the Recovery of Biomolecules

Aqueous two-phase flotation (ATPF), a novel technique which integrates the principles of aqueous two-phase systems and mass transfer mode of solvent sublation, has been successfully applied for the separation and purification of biological materials in the field of biotechnology. From the studies done so far, ATPF has demonstrated as an effective, economical and environment-friendly technique for separation of labile biomolecules from their crude aqueous extracts of natural plants or fermentation broths, under mild separation condition. In this article, the basic principles, experimental apparatus set up, key design variables of ATPF, ATPF applications and a comparative study between ATPF and other conventional methods are discussed. This review is intended to present a comprehensive summary on the research works carried out so far related to ATPF since its introduction in 2009 until present, which will be helpful for further research in ATPF.
Substituted pyrimidines. II. 1,3-Dimethylisocytosine and related compounds

1,3-Dimethyl-1,2-dihydro-2-imino-4(3H)pyrimidinone (1,3-dimethylisocytosine) was prepared by methylation of 2-amino-3-methyl-4(3H)pyrimidinone and was degraded in alkaline solution to a mixture of 3-methyl-2-methylamino-4(3H)pyrimidinone, 1,3-dimethyl-2,4-(1H,3H)pyrimid-indione, 2-methylamino-l-methyl-4(1H)pyrimidinone, 1-methyl-2,4-(1H,3H)pyrimidindione and 3-methyl-2,4-(1H,3H)pyrimidindione. Thiation of the title compound gave both 1,2-dihydro-1,3-dimethyl-2-thio-4(3H)pyrimidinone and 1,3-dimethyl-2,4-(1H,3H)pyrimidinedithione. The title compound is a tautomerically fixed pyrimidine and its uv spectra were compared with related compounds, notably 3-methyl-2-dimethylarnino-4(3H)pyrimidinone which is also tautomerically fixed.
On the Evolution of the Rate of Polymerization, Number and Size Distribution of Particles in Styrene Emulsion Polymerization Above CMC

This work is an extension of a communication reported by two of the authors [Carro and Herrera-Ordonez, Macromol Rapid Commun 2006, 27, 274], where bimodal particle size distributions (PSD), obtained by asymmetric flow-field flow fractionation (AFFF, AF4), were taken as evidence of certain degree of stability of primary particles. Now, emulsion polymerizations of styrene were performed under conditions employed before by other researchers, intending to examine if the behavior observed is general. The number of particles (N) and PSD were studied by means of dynamic light scattering and AF4. By the later, bimodal PSDs were detected in all cases, where the population corresponding to primary particles (diameter <20 nm) depends on reaction conditions. Regarding N, AF4 results show that it is constant during interval II, in contrast to DLS results. Primary particle coagulation was evidenced as minimums in N evolution and the rate of polymerization curves, monitored by calorimetry and gravimetry, which are enhanced when higher particle number is generated and/or the ionic strength is increased. These results suggest that particle coagulation is not as extensive as it would be expected according to the coagulative theory. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3152–3160, 2010
Enantiomeric separation of five amino acids by high‐performance liquid chromatography on a chiral crown ether column

A chiral liquid chromatographic method was validated to analyze the D-and L-enantiomers of five amino acids contained in a commercial solution: aspartic acid, leucine, lysine, phenylalanine, and valine. These 10 compounds were separated on a chiral crown ether column with a mobile phase composed of water adjusted to pH 1.5 with perchloric acid, with ultraviolet detection at 220 nm. The method was applied to the commercial amino acid solution before and after sterilization by 5 kGy irradiation; no stereoconversion was observed following sterilization. Chirality 9:150–152, 1997. © 1997 Wiley-Liss, Inc.
Preparation and Spherical Agglomeration of Crystalline Cerium(IV) Oxide Nanoparticles by Thermal Hydrolysis

Crystalline cerium(IV) oxide nanoparticles with a cubic fluorite structure could be synthesized from cerium(IV) ammonium nitrate solutions with a relatively high concentration of cerium(IV) (such as 0.5 mol/dm3) via thermal hydrolysis at 150°–240°C. The effects of the treatment temperature, the salt concentration, and the addition of sulfate ions on the crystallite size and morphology of the synthesized particles were investigated. The crystalline nanoparticles had a tendency to agglomerate and form spherical secondary particles with the addition of either ammonium sulfate or sulfuric acid. The existence of sulfate ions in the acidified solution was confirmed to be a factor of consequence for spherical agglomeration of the nanoparticles.
DESIGN OF PIC-CONTROLLED PULSED ULTRASONIC TRANSMITTER FOR MEASURING GINGIVA THICKNESS

The aim of this study is to design and implement a noninvasive ultrasonic thickness measurement device that determines the gingiva thickness, which is quite an important criterion in dentistry, by using A-mode ultrasonic method. Operating frequency of the device is selected as 8 MHz, since gingival thickness is quite slight. The measurements are performed as 192.5 μm precision by the implemented system. Surface-mounted devices integrated circuits (SMD ICs) and electronic parts are used in the implementation of the device. Thus, a small-dimension, handheld device has been design and constructed. The transmitter of the device is tested under simulated object, and encouraging results were obtained.
Physically meaningful modeling of the 3‐zone and 4‐zone simulated moving bed processes

This article is intended as a complement to a recent article in this journal, Comparative Study of Flow Schemes for a Simulated Countercurrent Adsorption Separation Process by Ching et al. (1992). These authors carried out experiments on continuous separation of three carbohydrate mixtures with both the usual four-section scheme and a three-section scheme: fructose-dextran (MW≅9400), raffinose-dextran (MW=6000), and fructose-raffinose. These two schemes were modeled as equivalent true countercurrent systems. From the experiments and model results they conclude that the equivalent true countercurrent model is fully adapted to represent the four-section scheme, but a major discrepancy arises with the three-section scheme: the raffinate concentration is not correctly predicted. From these results it may be concluded that when a physically meaningful modeling of the equivalent true countercurrent is realized, the apparent discrepancy disappears. From another standpoint, such a mismatch between the experiments and model predictions would not have been observed with a model that considers the periodic port motion. Such a model foresees a cyclic steady state where extract and raffinate compositions vary throughout the period T; they can be considered as constant only when averaged over the period. It is worth comparing the results of these two models, especially when the equivalent countercurrent representation is not very close to the physical phenomenon it should represent. We agree with their major finding that a three-zone scheme represents necessarily a higher desorbent demand than a four-zone scheme.
Biodegradation of Toxic Organics: Status and Potential

The ability of biological treatment systems to degrade toxic organic compounds is assessed through a review of the literature. While much general information is available, there is little kinetic information that can be used directly by engineers making decisions about process alternatives. Nevertheless, useful kinetic information can be obtained from biodegradation studies in which the toxic compound of interest serves as the sole substrate for microbial growth; a scheme is proposed whereby such information can be used in mathematical models to predict the extent to which the toxic compounds can be removed from complex waste streams. A methodology is also proposed whereby the impacts of the toxic compounds on the biodegradation of the biogenic organic material in the waste streams can be predicted. Finally, it is noted that new information about environmental biotechnology is being generated by biologists faster than engineers can assimilate and apply it. Thus, close alliances must be formed between engineers and scientists to fully exploit the potential offered by biotechnology.
Octan-1-ol–water partition coefficients of zwitterionic α-amino acids. Determination by centrifugal partition chromatography and factorization into steric/hydrophobic and polar components

The distribution coefficients of free α-amino acids have been measured around their isoelectric value by centrifugal partition chromatography (CPC), allowing the determination of the partition coefficient (log P) of the amino acids in their zwitterionic form. Good correlations with published distribution coefficients of amino acid derivatives allowed log P values to be calculated for the five amino acids (Arg, Asn, Asp, Glu, Lys) whose high polarity prevented direct measurements by CPC. The log P values were factorized into a steric component (molecular volume V, mainly accounting for inductive and hydrophobic forces) and a polarity factor (Λ, accounting for ion–dipole and dipole–dipole interactions and hydrogen-bonds) which correlates with other amino acid parameters expressing mainly polar interactions. Using two examples from the literature, we show that multiple linear regression analysis based on steric and polar parameters is able to afford a quantitative interpretation of factors influencing protein conformational stability.
Analysis of Fatty Acid Ethyl Esters in Hair by Headspace Solid-Phase Microextraction (HS-SPME) and Gas Chromatography-Mass Spectrometry (GC-MS)

Abstract Fatty acid ethyl esters (FAEE) can be used as alcohol markers in hair. The purpose of this study was to validate a new method for the detection of FAEE in hair, reducing the extraction time. Hair samples were analyzed by gas chromatography-mass spectrometry after headspace solid-phase microextraction with deuterated internal standards. Linear curves for ethyl myristate, palmitate and stearate were obtained in the range considered. The limits of detection were 0.8, 0.005, and 0.01 and the lower limits of quantification were 1.8, 0.01, and 0.4 for ethyl myristate, palmitate and stearate, respectively. Intra- and inter-assay precision and accuracy were less than 12.5% and 16.1%, respectively. Recoveries were higher than 13.5% in all cases. Finally, the method was applied to analyze hair of alcoholics, social drinkers, and teetotallers.
Effect of composition on aqueous polyurethane dispersions derived from polycarbonatediols

Aqueous polyurethane dispersions derived from isophorone diisocyanate, various polycarbonatediols of different molecular weights, and dimethylol butyric acid were prepared by a dispersing procedure modified to enhance molecular weight. Particle size, average molecular weight, and tensile properties were determined. The molar ratio of reactants affected the properties of the polyurethane dispersions significantly, with the trends described as the effects of their ionic group and polycarbonatediol soft-segment contents. The molecular weight of the polycarbonatediols also significantly affected the particle size of the aqueous polyurethane dispersions and the film properties. As the molecular weight of the polycarbonatediols decreased, the particle size of the aqueous polyurethane dispersions decreased, and the moduli of the cast films increased, as expected. However, the tensile strength of the cast films decreased as the molecular weight of the polycarbonatediols decreased because of the decrease in elongation at break. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4419–4424, 2006
Simultaneous Determination of Moisture, Organic Carbon, and Total Nitrogen by Near Infrared Reflectance Spectrophotometry

Near infrared diffuse reflectance spectrophotometry, within the wavelength range 1100 to 2500 nm, was investigated for use in the simultaneous prediction of the moisture, organic C, and total N contents of air-dried soils. An infraAlyzer 500 C (Technicon Instruments Corp.) scanning spectrophotometer was used to obtain near infrared reflectance of soils at 2-nm intervals. Calibration equations for each of the soil constituents studied were based upon selection of the best combination of three wavelengths in a multiple regression analysis. The wavelengths selected for moisture, organic C, and total N, respectively, were 1926, 1954, and 2150 nm, 1744, 1870 and 2052 nm, and 1702, 1870 and 2052 nm. The standard errors of prediction for finely ground samples (<0.25 mm) from the top layers (0-0.1, 0.1-0.2, 0.2-0.3, 0.3-0.6 m) were 0.58, 0.16, and 0.014% for moisture, organic C, and total N, respectively. The standard errors of prediction, however, were much larger for coarsely ground soils (<2 mm), soils containing low amounts of organic C (<0.3%) and total N (<0.03%), and for those with a wide range in colors. Within a narrow range in soil color and at moderate amounts of organic matter (0.3–2.5%C), the near infrared reflectance technique provides a rapid, nondestructive, and simultaneous measurement of moisture, organic C and total N in soils.
Separation of positional isomers of aromatic anions by capillary electrophoresis using quaternized porphyrazine ion in aqueous solution

Separation of the positional isomers of chlorobenzoates and naphthalenesulfonates by capillary electrophoresis was investigated. A quaternized porphyrazine ion was synthesized and used as an additive in aqueous electrolytic solution. The positively charged macromolecule dynamically coated the surface of the fused silica capillary and reversed the direction of electroosmotic flow. The positional isomers of aromatic anions were well separated by the ion association reaction and possibly by π-π interaction between macrocyclic cation and aromatic anions.
Synthesis and Optical Properties of Type II CdTe/CdS Core/Shell Quantum Dots in Aqueous Solution via Successive Ion Layer Adsorption and Reaction

3-Mercaptopropionic acid stabilized CdTe/CdS core/shell quantum dots (QDs) were prepared in an aqueous solution following the synthetic route of successive ion layer adsorption and reaction. The photoluminescence quantum yield of the CdTe QDs could reach 40%, from 8% of the bare core, via the control of the shell thickness. The CdTe/CdS QDs exhibited also a significant red shift of emission and excitation peaks when the shell layer grew. The experiments revealed that the CdTe/CdS QDs evolved from type I to type II core/shell structures with the increase of the shell thickness, and the evolution process is affected by the core size, shell thickness, surface quality of the core and shell, as unraveled by steady-state and time-resolved spectroscopy. The lack of photoluminescence lifetime lengthening was ascribed to the surface influence of the shell.
Investigation of 1-alkanols in organised solutions

Conductometric behaviour of 1-alkanols (C 5 -C 10 ) in organised solutions of sodium dodecylbenzenesulfonate (SDBS) is investigated. Interaction of each alkanol with anionic surfactant is reflected in terms of association constants, K c . It is observed that self-assembly of SDBS is induced by the alkanol addition. The depression in critical micelle concentration (CMC) of SDBS caused by each alkanol is translated to partition coefficient, K c by using interaction coefficient. The dimensionless partition coefficient, K x is utilized to highlight the energy efficiency of the solubilization process. The results indicate that even longer chain alkanols prefer interfacial area for their residence. The relative solubility of each alkanol is enhanced with increasing SDBS concentration. Such basic information could be vital for development of nano-scale assemblies for specific delivery of water soluble drugs. KEY WORDS : SDBS, Alcohols, Partition coefficient, Relative solubility, Conductometry Bull. Chem. Soc. Ethiop. 2011 , 25(3), 469-474.
Transformation of Silver Nanospheres into Nanobelts and Triangular Nanoplates through a Thermal Process

Silver has been prepared as triangular nanoplates with sharp corners and thin nanobelts by refluxing an aqueous dispersion of spherical colloids of silver with an average diameter of 3.5 nm. The spherical colloids of silver were, in turn, generated by reducing silver nitrate with sodium borohydride in the presence of poly(vinyl pyrrolidone) (PVP) and sodium citrate. Our studies indicate that the light present in an ordinary chemical laboratory was sufficiently strong to transform some spherical nanoparticles into small triangular nanoplates. Refluxing provided the driving force to facilitate the Ostwald ripening process−growth of these plate-like seeds at the expense of spherical nanoparticles. In addition, refluxing might also selectively disrupt the organic layers on the surfaces of the small triangular nanoplates, driving these plates to assemble into thin nanobelts due to the strong dipole−dipole interaction between adjacent plates. These nanostructures of silver with unique planar shapes might find u.
Validation of Mometasone furoate and CIP100 Residue Analysis Methods After Cleaning of Production Equipment in the “XYZ” Pharmaceutical Industry

In this study, the HPLC and Total Organic Carbon (TOC) analysis methods have been developed and validated for the determination of the amount of Mometasone furoate and CIP100 residues on the surface of production equipment and to confirm the efficiency of the cleaning procedure. Mometasone furoate and CIP100 have been chosen based on the worst case assessment approach. The limit of mometasone furoate contamination that has been determined is 100 ug/swab and the specified limit of CIP100 contamination is 100 ug/swab which should not be exceeded during sequential cleaning of the equipment. Mometasone furoate shows good linearity in the range 0.1-1.0 ppm for the HPLC method and CIP100 2.0-10.0 ppm for TOC Analysis. The percentage of recovery from stainless steel plates using swab sampling techniques was found in the limits of 95.12% and 99.93% respectively in the HPLC and TOC methods. Both methods are simple, inexpensive, short analysis time and high sensitivity for quantitative determination of Mometasone furoate and CIP100 on the surface of manufacturing equipment well below the contamination limit. The validated method meets the requirements for demonstration of the validation of residual cleaning of mometasone furoate and CIP100 on the surface of production equipment
Reinvestigation of seselin

The crystal structure of seselin (2′,2′-dimethyl-3-pyreno[6,5:7,8]coumarin), C14H12O3, a bioactive pyrenocoumarin, has been reinvestigated. The coumarin ring system is nearly planar and the α-pyran ring adopts a distorted half-chair conformation. An inter­molecular C—H⋯O hydrogen bond is observed.
Hybrid chemical-thermal process using NaBH4 to obtain reduced multi-layered graphene oxide

Using glassy carbon (GC) as matrix material made it possible to obtain graphite oxides using the Hummers-Offeman method. After this procedure, it was possible to synthesize the graphite oxide (GrO) and the reduced multi-layer graphene oxide (rMGO). On this form, we propose the reduction, via hybrid method, which consists on the thermal and chemical reduction in presence of NaBH4, in order to obtain GrO and rMGO. In this way, using FTIR and Raman spectroscopy we determinate the functional groups existent, the nanocrystal size, the distance between defects, the defects density and the optical gap in those systems. With this, we observe that the hybrid reduction is an efficient method for reducing the defects on the graphite oxide and consequently the decrease of optical gap. Finally, a morphological study by AFM was made on the rMGO, observing that these have nanometric
Determining electron temperature and electron density in moderate pressure H2/CH4 microwave plasma

The electron temperature and electron density are measured in a microwave (MW) plasma-assisted chemical vapour diamond deposition reactor for different experimental conditions by varying the substrate temperature, methane content and MW power density. Optical emission spectroscopy (OES) and MW interferometry are used to probe the discharge generated in a stainless steel resonant cavity excited at a frequency of 2.45 GHz. Changing the substrate temperature from 630 to 900 °C does not show any significant influence on the electron temperature or on the electron density. Increasing the methane content from 0 to 10% does not lead to any modification of the electron temperature or density. However between 10% and 20% CH, a decrease of the electron density is observed which may be attributed to soot particle formation. The electron density increases in the range of (1.2–10) × 1011 cm−3 from moderate power density conditions (50 hPa/1000 W) to high power density conditions (250 hPa/3500 W). OES measurements show that the electron temperature exhibits a flat axial profile in the plasma bulk and ranges from 14 000 K at (25 hPa/600 W) to 10 500 K at (400 hPa/3000 W).
MEMBRANE SURFACE MODIFICATION AND BACKPULSING FOR WASTEWATER TREATMENT

Using a novel photoinduced grafting method, hydrophobic polypropylene (PP) membranes were rendered hydrophilic by grafting monomers of poly(ethylene glycol 200) monomethacrylate (PEG200MA), dimethyl aminoethyl methacrylate (DMAEMA), or acrylic acid (AA), to produce a neutral, positive, or negative charge, respectively, on the membrane surface. Using both unmodified and modified PP membranes, as well as a hydrophilic cellulose acetate (CA) membrane, the effects of backpulsing and surface chemistries on membrane fouling were investigated for crossflow microfiltration of bentonite clay suspensions and crude oil emulsions. Without backpulsing, the permeate volumes collected over 60 min were not strongly dependent on membrane surface chemistry and morphology for the filtration of either clay or oil. With backpulsing, however, 5-fold and 6-fold permeate enhancements were obtained by backpulsing alone and by a combination of backpulsing and surface modification, respectively, for clay filtration. The recovered water fluxes after backwashing the PP membranes fouled without backpulsing were approximately 80% of the initial water flux, showing that bentonite fouling is primarily nonadhesive. However, the recovered fluxes with backpulsing were slightly less than those without backpulsing, due to internal fouling after each backpulse. For the filtration of crude oil, 1.3-fold and 2.7-fold permeate volume enhancements were obtained by backpulsing alone and by a combination of backpulsing and surface modification, respectively. More than a 3-fold permeate volume enhancement was obtained upon adding an anionic or cationic surfactant to the oil mixture when the modified membrane was similarly charged. The recovered flux after backwashing the unmodified PP membrane fouled without backpulsing or surfactant was only about 30% of the initial water flux, indicating adhesive primarily fouled by oil, but the recovered flux doubled when the membranes were rendered hydrophilic by surface modification.