Miracle-dz/UniFAR-FTUs huggingface dataset:
Investigation of human biomarkers in exhaled breath by laser photoacoustic spectroscopy

The paper underlines the importance of breath tests in medicine and the potential of laser techniques to measure in-vivo and in real time human biomarkers. The presence of trace amounts of gases or the metabolites of a precursor in exhaled air could be linked to kidney or liver malfunction, asthma, diabetes, cancer, ulcers or neurological disorders. The measurement of some human biomarkers (ethylene, ammonia), based on laser photoacoustic spectroscopy methods, insure very high sensitivity and selectivity. The technical characteristics of this instrument were measured to determine the detection limits (sub-ppb for ethylene). The results of ethylene release following lipid peroxidation initiated by X-ray irradiation or ingestion of radioactive compounds are presented. The possibility to extend this technique for measurement of breath ammonia levels in patients with end-stage renal disease while they are undergoing hemodialysis is discussed.
Wetting of Planar Surfaces by a Gay-Berne Liquid Crystal

Molecular simulation of the wetting of an unstructured attractive wall by Gay-Berne liquid crystals are reported. Simulations are performed in the grand canonical ensemble on a wide pore at constant temperatures of T *=0.53 and 0.56, corresponding to temperatures below and above the nematic-isotropic-vapor triple point. Close to the coexistence chemical potential, a thick liquid film wets the solid surface. The film is composed of stratified layers of molecules parallel to the solid surface, which follow to a nematic domain at the lower temperature and an isotropic one at the higher temperature. In both cases, the film is in equilibrium with the corresponding vapor phase. Close to the liquid-vapor interface there is a manifest tendency for the molecules to orient themselves parallel to the interface. The adsorption on the wall varies continuously with the thermodynamic parameters considered and no evidence of a first order prewetting transition is observed.
Cadmium Tellurium Quantum Dots in Sol-Gel-Derived Silica Spheres Coated with Calix[6]Arene as an Optical Probe for Dalapon

This paper reports a new optical probe for detect dalapon. We have synthesized the luminescent and stable CdTe quantum dots(QDs) capped with calix[6]arene(C[6]/SiO2/CdTe) via the sol-gel technique in aqueous media. These hybrid organic-inorganic compounds are characterized by IR spectroscopy, ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and fluorescence. We found that the C[6]/SiO2/CdTe were more stable and had higher fluorescence than the SiO2/CdTe nanoparticles (NPs). The C[6]/SiO2/CdTe show selectivity and sensitivity to dalapon via significant fluorescence intensity decrease. It can be ascribed to the Stern-Volmer equation. Under the optimal conditions, the relative fluorescent intensity was decreased linearly with increasing dalapon concentration in the range of 1.0–25.0 nmol/L with a detection limit of 0.262 nmol/L of dalapon. The possible underlying mechanism is discussed by Langmuir binding isotherm.
Water desalination using R141b gas hydrate formation

AbstractIn this paper, water desalination was performed by R141b hydrate formation in systems containing refrigerant and a brine aqueous solution to determine of R141b hydrate growth rate and efficiency of process. Kinetic experiments were conducted with initial temperatures of 0, 2, and 4°C with saline concentrations of 1, 2, 4, and 6% weight of NaCl and also with the molarity 0.304 mol/L of NaCl, KCl, CaCl2, and MgCl2 aqueous solutions. The results show that R141b hydrate formation rate depends on the saline concentration, initial temperature, and salt type. Moreover, the results of water desalination based on R141b hydrate formation indicate that the removal efficiency depends on the ionic size and electrical charge. Each dissolved mineral is removed in following order: with 59–70% of efficiency.
Study of Liquid Crystal Prewetting Films by Atomic Force Microscopy in Tapping Mode

We demonstrate the use of tapping mode atomic force microscopy (TMAFM) for the study of liquid crystal prewetting films spreading on silicon wafers. With AFM, we are able to image the edge of the prewetting film when it spreads on the solid and to obtain images on its surface with a resolution in the nanometer range. As an example, we study the roughness of the film surface: we have observed, in agreement with theoretical predictions, that the undulations of the liquid films follow those of the solid surface (at least when the wavelength of the undulations is large compared to the film thickness (∼5 nm)). Further, we show that when the drive amplitude or the set point is below a threshold, a liquid crystal micromeniscus forms between the tip and the sample, causing an instability of the tip. Finally, we have also observed that the apparent thickness of the film depends on the imaging parameters in a way that cannot be described by the models that are generally used to explain tapping mode operations.
Physical Models of Plasma Microfield

The present review is devoted to the current status of microfield notion that was so successful and profitable for experimental and theoretical studies of plasma in gas discharges and thermonuclear modeling installations for many decades. The physical aspects and ideas of the main generally used microfield models are described and analyzed in detail. The review highlights the remaining vague and unclear questions in the subject.
On the calculation of specific heats, thermal pressure coefficients and compressibilities in molecular dynamics simulations

Expressions are derived for the specific heat, Cv , the thermal pressure coefficient, γ v , and the adiabatic compressibility, β S , in terms of the fluctuations of the kinetic energies and the microscopic ‘ pressure function ’ in the microcanonical ensemble by direct extension of an analysis by Lebowitz et al. [1]. The present results apply to rigid polyatomic molecules and are tested with molecular dynamics results for a diatomic system.
The Calcium Isotope Composition (δ44/40Ca) of NIST SRM 915b and NIST SRM 1486

The calcium isotopic composition of NIST SRM 915b and 1486 provided by the National Institute of Standards and Technology was analysed. The δ44/40Ca values of the two reference materials relative to NIST SRM 915a were: NIST SRM 915b =+0.72 ± 0.04‰ and NIST SRM 1486 =−1.01 ± 0.02‰. NIST SRM 1486 did not require any chemical separation prior to measurement.
MECHANISM FOR FINGER PERSISTENCE IN HOMOGENEOUS, UNSATURATED, POROUS MEDIA: THEORY AND VERIFICATION

Wetting-front instability, or gravity-driven fingering, can occur during vertical infiltration. Previous studies found that fingers persist over long periods of constant infiltration and in subsequent infiltration cycles. We present a physically based theory to explain finger persistence. The theory is tested using a new technique in which moisture contents are visualized by the transmission of light through unsaturated sand, recorded with a video camera, and then analyzed by video digitizing computer hardware. Theory and experiments show that hysteresis in the moisture characteristic relationship explains the persistence of fingers in time.
Synthesis and Antibacterial Activity of New Oxadiazolo[1,3,5]triazine, 1,2,4-Triazolo and Thiadiazolo[1,3,4]oxadiazole Derivatives.

3-Formyl-4-hydroxycoumarin has been treated with semicarbazide to give 4-hydroxy-2-oxo-2H[1]-benzopyran-3-aldehyde semicarbazone la-d, which on oxidative cyclization with bromine in glacial acetic acid in the presence of anhydrous sodium acetate gives 3-(5-amino-1,3,4-oxadiazol-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one 2a-d. 3-(5-amino-1,3,4-oxadiazol-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one on reaction with benzaldehyde gives 4-hydroxy-3-(5-benzylidine imino 1,3,4-oxadiazol-2-yl)-2H[1]-benzopyran-2-one 3a-d. 3a-d on (4+2) cycloaddition with phenyl isothiocynate gives 3-(6,7-diphenyl-5-thioxo-6,7-dihydro-5H-[1,3,4]oxadiazolo[3,2-a][1,3,5]triazin-2-yl)-4-hydroxy-2H[1]-benzopyran-2-one 4a-d. 2a-d undergoes regioselective condensation with KSCN in methanol to give N-[5-(4-hydroxy-2-oxo-2H[1]-benzopyran-3-yl)-1,3,4,-oxadiazol-2-yl]thiourea 5a-d whereas with phenyl isothiocynate it gives N-[5-(-4-hydroxy-2-oxo-2H[l]benzopyran-3-yl)-l,3,4-oxadiazole-2-yl]-N'-phenylthiourea 7a-d. 5a-d reacts with thionyl chloride in pyridine to give 4-hydroxy-3-(6-thioxo-5,6-dihydro[ 1,2,4]triazolo[5,1-b][1,3,4]oxadiazol-2-yl)-2H[1 ]-benzopyran-2-one 6a-d. 7a-d on treatment with ethanol and iodine yields 4-hydroxy-3-[6-phenylimino-6H-[l,2,4]-thiadiazolo[3,2-b][1,3,4]-oxadiazol-2-yl]-2H/[1]benzopyran-2-one 8a-d.
Crystallization of metal substituted ferrihydrites

The effects of a series of divalent, first row transition elements, i.e. Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ on the crystallization of ferrihydrite have been compared. With the exception of Mn2+, the metal ions considered, stabilized ferrihydrite and enhanced the amount of haematite in the reaction product. The stabilizing ability of these ions could be related to the increase in covalency of these metals along the series. With more than 15 mole% divalent metal ion present, ferrihydrite transformed to a spinel phase by a dissolution/reprecipitation mechanism. These metals can replace some Fe3+ in the structures of the crystallization products. Factors that influence the extent of isomorphous substitution are the match between the radii and charges of Fe3+ and the substituent ions and also, the congruency of dissolution of the M/ferrihydrite coprecipitate. Kristallisation von metall-substituiertem Ferrihydrit Der Einflus der M2+-Ionen der 1. Ubergangsmetall-Periode (M = Mn2+, Co2+, Ni2+, Cu2+, Zn2+) auf die Umwandlung von Ferrihydrit wurde untersucht. Mit Ausnahme von Mn2+ stabilisierten alle M2+ Ferrihydrit und erhohen den Anteil von Haematit (gegenuber demjenigen von Goethit) im Endprodukt. Die stabilisierende Wirkung dieser Ionen kann der Zunahme des kovalenten Charakters der entsprechenden Metalle zugeordnet werden. In Anwesenheit von uber 15 mol%-M2+ wandelt sich Ferrihydrit uber einen Auflosungs-Wiederausfallungsmechanismus in eine Spinellphase um. Die M2+ konnen einen Teil der Fe3+ in den Kristallgittern der Endprodukte (Goethit und Haematit) ersetzen. Das Ausmas dieser Substitution wird von Passfehlern des Ionenradius gegenuber dem Radius des Fe3+ beeinflust, aber auch von der Auflosungsgeschwindigkeit der M2+/Ferrihydrit-Co-Prazipitation.
Bimetallic Gold-Palladium Supported on 5A Zeolite and their Catalytic Activity for Vinyl Acetate Synthesis

5A zeolite supported Gold-Palladium (Au-Pd) bimetallic were prepared and used in vapor phase oxidation of ethylene to synthetize vinyl acetate (VA). The chemical composition of Au-Pd/5A zeolite catalyst was analyzed by a combination of atomic absorption spectrometry (AAS). The structure of Au-Pd/5A zeolite catalyst was characterized by a scanning electron microscopy (SEM) and X-ray diffraction (XRD). The catalytic activity of the Au-Pd/5A zeolite catalyst under laboratory conditions were investigated in vinyl acetate synthesis by a kind of the fixed bed reaction device. The AAS testing showed that Au and Pd supported rate were increased up to the optimum value 91.22% and 93.91% respectively at the ratio of Au/Pd=0.87. The SEM analysis results indicated that Au-Pd alloy particles of 5A zeolite catalyst can grown up and reunited obviously through before and after reaction. The XRD analysis results showed that diffraction peak of Pd (111), Pd (200), Au (111) and Au (200) became sharp gradually with the extension of reaction time, crystalline phase composition and grain size of catalyst became bigger gradually. The results about catalytic activity of the Au-Pd/5A zeolite catalyst shown that with the increasing of the Au/Pd ratio, the space-time yield and selectivity have a best value respectively; when the ratio of Au/Pd=0.87, the space-time yield were 702g/(Lh) and the selectivity were 92.8% at the ratio of Au/Pd =1.13.
Solvation dynamics of fluoroprobe in diethylether

We present classical molecular dynamics simulations of the solvation dynamics of a strongly polar dye molecule in a weakly polar solvent. Solvation times and amplitudes are compatible with recent measurements. Several differences in the solvation dynamics relative to the widely studied case of strong polar solvents are exhibited: lesser importance of the inertial component of the Stokes shift, relaxation times close to individual solvent reorientational times, instead of the longitudinal relaxation time of the solvent, large amplitudes of translational and orientational relaxation over about 10 ps and the presence of a long-lived solvation shell in the excited state.
Synthesis of aPHB-PEG Brush Co-polymers through ATRP in a Macroinitiator–Macromonomer Feed System and Their Characterization

A brush co-polymer composed of a biodegradable hydrophobic poly((R,S)-3-hydroxybutyrate) chain and biocompatible hydrophilic poly(ethylene glycol) brushes was designed as amphiphilic self-aggregating species with potential application in the health-care field. The co-polymer was prepared applying a three-step procedure: (i) ring-opening anionic polymerization of (R,S)-β-butyrolactone initiated by 2,2-bis(hydroxymethyl)butyric acid tetrabutyl ammonium salt yielding polyester with two hydroxyl functionalities at one chain terminus, (ii) synthesis of PHB-derived microinitiator species and (iii) ATRP of polyethylene glycol methyl ether methacrylate yielding an amphiphilic co-polymer. Chain structures and/or end-group functionalization were proven by 1H- and 13C-NMR spectroscopy of the products at each step of the synthetic procedure. The molecular weight and structure of the end-product were close to the expected values. The self-aggregation behavior of the brush co-polymer in an aqueous medium was evidenced by optical absorption probe technique and dynamic/static light scattering measurements.
Activity and Stability of Ordered and Disordered Co‐Pt Alloys for Phosphoric Acid Fuel Cells

Co-Pt alloys were studied in detail by a corrosion test under phosphoric acid fuel cell (PAFC) conditions on the well-defined crystallographic structures for a typical combination of the alloy catalysts used in PAFCs, examining the long-life stabilities of the structures and the catalytic activities for O[sub 2] electroreduction. The ordered (O) and disordered (D) alloys at the same particle sizes can be obtained by heat-treating the mother alloy in different temperature sequences. The O-alloy exhibits a specific activity 1.35 times higher than the D-alloy before the corrosion test, but shows less activity after the corrosion test, due to a higher degradation in the O-alloy activity as compared with that of the D-alloy. It was found that the Co atoms on particle surfaces of both alloys dissolved easily in the acid. This is followed by a second slow dissolution from inside the alloy particles probably due to the protective action by a monolayer thickness of Pt remaining on the alloy surfaces, but the loss of Co in the second stage dissolution for the O-alloy is higher by several percentage points compared to that of the D-alloy. It was also found that the Pt content does not change on the catalyst supportmore » even after 50 h of corrosion test, but the pure Pt phase is formed in the corrosion product, where the phase for the O-alloy grows faster than that for the D-alloy with corrosion time. Based on these results, obtained by chemical, x-ray diffraction, and transmission electron microscopy with energy dispersive spectroscopy analyses, the corrosion for Pt alloy catalysts is clearly explained: after the dissolution of Co atoms in the first surface layer of alloys, both Co and Pt dissolve out simultaneously from small-size alloy particles and the Pt redeposits on the surfaces of large-size alloy particles. It is concluded that the D-alloy is preferable to the O-alloy from the viewpoint of the stabilities in the structure and the electrocatalytic activity. « less
Exact and approximate solutions of the utilization and yield equations for O2(1Δ) generators

A mathematical model for the production of singlet delta oxygen from the reaction of a gas containing chlorine with the hydroperoxy ion in liquid basic hydrogen peroxide is reviewed. An exact solution for the Cl2 utilization, O2(1(Delta) ) yield, and efficiency of the generator is obtained in the well-stirred limit (WSL) for which the surface concentration of HO2- is constant. A universal set of performance curves is presented and the implications when assessing generator performance are discussed. When depletion of the surface concentration of HO2- is important, perturbation theory is used to obtain a solution for the generator's utilization, yield, and efficiency which is a generalization of the corresponding WSL solution. A criterion for the validity of the perturbation solution is obtained and it is shown that the performance of a rotogenerator plateaus not too far above the value of disk rotation rate predicted by this criterion. Finally an integral method is used to obtain a simple, but approximate, solution of the utilization-yield equations which applies over a wide range of operating conditions.
Effect of Fenton's reagent on the degradability of CI Reactive Yellow 15

As an advanced oxidation method, Fenton's reagent has an advantage that it combines both oxidation and coagulation techniques. The aim of this study was to efficiently operate Fenton's reagent oxidation to degrade a reactive dye, CI Reactive Yellow 15, which is non-biodegradable and has high chemical oxygen demand. In addition, performance of the Fenton oxidation process for dye solution was determined by measuring the chemical oxygen demand and colour removal. The influence of the main operating parameters, iron sulphate and hydrogen peroxide concentration, pH, temperature and dye concentration have been studied, in a batch-type operation. The results obtained show that the best pH value for decolorisation was pH 3, with an average decolorisation of 98.7% and average removal of chemical oxygen demand ca. 93.3% at 15 °C for a 0.065 molar ratio of Fenton's reagent. An increase in temperature resulted in higher removal rates.
Dispersion and Absorption in Dielectrics I. Alternating Current Characteristics

The dispersion and absorption of a considerable number of liquid and dielectrics are represented by the empirical formula e*−e∞=(e0−e∞)/[1+(iωτ0)1−α]. In this equation, e* is the complex dielectric constant, e0 and e∞ are the ``static'' and ``infinite frequency'' dielectric constants, ω=2π times the frequency, and τ0 is a generalized relaxation time. The parameter α can assume values between 0 and 1, the former value giving the result of Debye for polar dielectrics. The expression (1) requires that the locus of the dielectric constant in the complex plane be a circular arc with end points on the axis of reals and center below this axis.If a distribution of relaxation times is assumed to account for Eq. (1), it is possible to calculate the necessary distribution function by the method of Fuoss and Kirkwood. It is, however, difficult to understand the physical significance of this formal result.If a dielectric satisfying Eq. (1) is represented by a three‐element electrical circuit, the mechanism responsible.
Synthesis and properties of waterborne polyurethane adhesives: effect of chain extender of ethylene diamine, butanediol, and fluoro-butanediol

Waterborne polyurethane (WBPU) adhesives were prepared using poly(tetramethylene oxide glycol), 4,4’-dicyclohexylmethane diisocyanate (H12MDI), hydrophilic agent dimethylol propionic acid and chain extender of 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD), ethylene diamine (EDA), and 1,4-butanediol. All three chain extenders have been used as single and mixed (different ratio) content during synthesis, and the effect of chain extender and their content to the properties of tensile strength, Young’s modulus, water swelling (%), and adhesive strength was investigated. The adhesive strength value was higher using EDA as a single-chain extender; however, the potentiality of adhesive strength under water was improved using mixed-chain extenders of EDA and TFBD in WBPU adhesives. The maxima potentiality was observed with 6.31 mole% TFBD and 2.10 mole% EDA in WBPU adhesives.
Large Enhancement in Photocurrent Efficiency Caused by UV Illumination of the Dye-Sensitized Heterojunction TiO2/RuLL‘NCS/CuSCN: Initiation and Potential Mechanisms

Wide-band-gap, dye-sensitized, heterojunctions of the composition n-TiO2/Ru-dye/p-CuSCN undergo large increases in efficiency when subjected to low-power UV illumination (<40 mW/cm2) for periods between 10 and 30 min. Ru-dye refers to any of several ruthenium polypyridyl dyes. The UV illumination increases the incident-photon-to-current-efficiency for light absorbed by the dye by a factor of 5−10 and increases the open circuit voltage by 100−300 mV. This beneficial effect is stable for months after the UV illumination is terminated. Investigation of the effects of varying the UV wavelength and the applied bias show that the reaction(s) responsible for the increase in efficiency begin with the oxidation of some interface species by a photoexcited hole in the TiO2 valence band. Treatment of the TiO2/dye/CuSCN cells with oxidized thiocyanate in solution causes a similar increase in the efficiency of dye sensitization. Results from TiO2 and CuSCN photoelectrochemical cells are also presented. The combined res.
HYDROPHOBIC FORCE FIELD AS A MOLECULAR ALTERNATIVE TO SURFACE-AREA MODELS

An effective force field for hydrophobic interactions is developed based on a modified potential-of-mean-force (PMF) expansion of the effective many-body interactions between nonpolar molecules in water. For the simplest nonpolar solutes in water, hard particles, the modified PMF expansion is exact in both limiting cases of infinite separation and perfect overlap. The hydrophobic interactions are parametrized by using the information-theory model of hydrophobic hydration. The interactions between nonpolar solutes are short-ranged and can be evaluated efficiently on a computer. The force field is compared with simulation data for alkane conformational equilibria in water as well as a model for the formation of a hydrophobic core of a protein. The modified PMF expansion can be extended to solutes with attractive interactions. The observed accuracy, computational efficiency, and atomic detail of the model suggest that this simple hydrophobic force field can lead to a molecular alternative for phenomenologica.
Women’s leadership in education: A perspective from Chilean school leaders

This paper focuses on the experiences of six Chilean female headteachers. It addresses their career progress, and the facilitators and barriers, as well as the challenges they encountered in accessing and enacting school leadership. The six participants were drawn from all three of Chile’s school types – public, semi-private and private – in what is a differentiated system. The findings demonstrate both differences and similarities in participants’ experiences, across all three school sectors. A major difference relates to the additional barriers faced by public sector school leaders, compared with participants in the private and semi-private schools.