Miracle-dz/UniFAR-FTUs huggingface dataset:
ANALYTICAL METHOD DEVELOPMENT AND VALIDATION OFUV SPECTROSCOPIC METHODFOR SIMULTANEOUS ESTIMATION OF ZALTOPROFEN AND PARACETAMOL IN COMBINED DOSAGE FORM

A simple, accurate, precise & sensitive UV spectroscopic method was developed for the simultaneous determination of zaltoprofen (ZLT) & paracetamol (PCM) in combined tablet dosage form. For the simultaneous equation method, the wavelength range of both the drugs zaltoprofen & paracetamol were selected as 227 nm and 243 nm. The linearity was found in the concentration range of 1 to 5 µg/ml and 4.06 2 to 20.31 µg/ml for zaltoprofen and paracetamol, respectively. The slope, intercept, correlation coefficient values of zaltoprofen & paracetamol at 227 nm & 243 nm were found to be 0.032, 0.047, 0.999 (227 nm); 0.029, 0.043, 0.998 (243 nm) & 0.041, 0.073, 0.999 (227 nm); 0.059, 0.095, 0.999 (243 nm) . The % recovery values were found to be 98.66 % - 99.09 % for zaltoprofen and 98.40 % - 98.86% for paracetamol, stated that the method was accurate. The LOD and LOQ values of both the drugs zaltoprofen & paracetamol were found to be 0.216 µg/ml, 0.656 µg/ml (227 nm); 0.238 µg/ml, 0.724 µg/ml (243 nm) & 0.225 µg/ml, 0.682 µg/ml (227 nm); 0.117 µg/ml, 0.355 µg/ml (243 nm). This method was successfully applied to the determination of zaltoprofen & paracetamol content in marketed formulation. The method was validated statistically as per ICH guideline. The results proved that the method can be employed for the routine analysis of zaltoprofen & paracetamol in
Investigation on 2-mercaptobenzothiazole behavior as corrosion inhibitor for 316-stainless steel in acidic media

Purpose – The purpose of this paper is to describe the behavior of 2-mercaptobenzothiazole (MBT) on the corrosion of 316 stainless steel (SS) in acidic media and the mechanism of its action. Design/methodology/approach – The inhibitive effect of MBT towards the corrosion of 316 SS in acid solution is studied by means of weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. The effect of inhibitor concentration and temperature against inhibitor action is investigated. Adsorption isotherm and adsorption mechanism are also discussed. Findings – MBT acts as inhibitor for this type of steel in acidic medium. This compound is mixed-type inhibitor and inhibition efficiency increased with increasing inhibitor concentration. MBT retards the rate of both anodic and cathodic corrosion reactions by adsorbing and forming a layer on the steel surface and the adsorption obeys Temkin adsorption isotherms. The inhibition efficiency is temperature dependence in the range from 25 to 65°C and.
DYNAMIC WETTING STUDIED BY MOLECULAR MODELING SIMULATIONS OF DROPLET SPREADING

The spontaneous spreading of liquid droplets is studied by molecular modeling simulations. By considering very large systems, we are able to study the influence of the solid−liquid interactions on the overall wetting dynamics. It is shown how microscopic parameters, such as the mobility of the molecules near the solid−liquid interface, can be measured. At the same time, relevant macroscopic parameters, such as dynamic contact angles and flow fields, are calculated from the simulations. The results strongly support the microscopic validity of the molecular-kinetic model of wetting.
Investigation of the Chemistry of Oxygen Delignification of Low Kappa Softwood Kraft Pulp using an Organic/Inorganic Chemical Selectivity System

Abstract Oxygen delignification (OD) of low kappa softwood kraft pulp was examined in two steps without inter‐stage washing as part of an overall program to evaluate the efficiency of a selectivity enhancement system consisting of phenol and magnesium sulfate. Black liquor carryover in the reaction system did not substantially affect delignification and the selectivity of these OD reactions. The residual lignins from both the original pulp and oxygen‐delignified pulp with and without the phenol/MgSO4 selectivity enhancement system were prepared and characterized using NMR spectroscopy. The effluent lignins after oxygen delignification were also prepared and characterized. The lignin characterizations provided the basis for the rationalization of the selectivity observed. A significant finding of this study was that the phenol/MgSO4 system in the oxygen delignification reaction appeared to hinder phenolic guaiacyl unit condensation. It also appeared to enrich the levels of p‐hydroxyphenyls in the residual lignin.
The Effects of Thermal Treatments on Microstructure Phosphorus-Doped ZnO Layers Grown by Thermal Evaporation

The ZnO films doped with 3 wt% phosphorus (P) were produced by activating phosphorus doped ZnO (ZnO:P) thin films in oxygen (O2) ambient at 600°C for 30, 60, 90 and 120 min, respectively. As-deposited films doped with phosphorus are highly conductive and n type. All the films showed p-type conduction after annealing, in an O2 ambient atmosphere. The activation energies of the phosphorus dopant in the p-type ZnO under O2 ambient gases indicate that phosphorus substitution on the O site yielded a deep level in the gap. With a further increase of the annealed durations, the crystalline quality of the ZnO:P sample is degraded. The best p-type ZnO:P film deposited at 600°C for 30 min shows a resistivity of 1.85 Ω cm and a relatively high hole concentration of 5.1 × 1017cm–3 at room temperature. The films exhibit a polycrystalline hexagonal wurtzite structure without preferred orientation. The mean grain sizes are calculated to be about 60, 72, 78, 85 and 90 nm for the p-type ZnO films prepared at 600°C for 30, 60, 90 and 120 min, respectively. Room temperature photoluminescence (PL) spectra of the ZnO film exhibit two emission bands — paramount excitonic ultraviolet (UV) emission and weak deep level visible emission. The excellent emission from the film annealed at 600°C for 30 min is attributed to the good crystalline quality of the p-type ZnO film and the low rate of formation of intrinsic defects at such short duration. The visible emission consists of two components in the green range.
Kinetics of catalyzed and non‐catalyzed soot oxidation with nitrogen dioxide under regeneration particle trap conditions

BACKGROUND: For compliance with the regulations on diesel particulate matter, car manufacturers have developed diesel particulate filters (DPF). These technologies require a regeneration method which oxidizes soot deposits in the filter. In diesel exhaust emissions there are two suitable oxidizing gases: oxygen and nitrogen dioxide. Nitrogen dioxide is much more active than O₂ and can directly attack the carbon surface. This work describes the kinetics of the oxidation of soot by NO₂ over a wide range of conditions relevant for DPF.RESULTS: The catalyzed and the non-catalyzed oxidation of soot have been performed in a fixed-bed reactor. The experimental results show that the overall oxidation process can be described by two additive parallel reactions: a direct C - NO₂ reaction catalyzed by H₂O and a cooperative C - NO₂ - O₂ reaction catalyzed by the Pt/Al₂O₃ catalyst. The results obtained allow to propose the following kinetic law for the specific rates of the catalyzed and the non-catalyzed oxidation of soot in the regeneration filter conditions: $$\eqalign{ r\left(s^{-1}\right) &= 0.48\ \exp \left({-\,26700\over RT}\right)X_{NO_{2}}^{0.6} + 1395\ \exp \left({-\,47800\over RT}\right) X_{NO_{2}}X_{O_{2}}^{0.3} \cr r_{cat}\left(s^{-1}\right) &= 0.51\ \exp \left({-\,26800\over RT}\right)X_{NO_{2}}^{0.6} + 51.4\ \exp \left({-\,52200\over RT}\right)\ X_{NO_{2}}^{0.4}X_{O_{2}}^{0.3} \cr }$$CONCLUSION: The kinetic parameters describing the oxidation rate of soot by NO₂ over a range of temperature and gas composition have been obtained. The extracted kinetics data are relevant for modeling the removal of trapping soot in automotive gas exhaust technology. Copyright
BOUNDARY CONDITIONS IN MODELING WATER FLOW IN UNSATURATED SOILS

Simultaneous physical and mathematical modeling has been employed to prove that the Richards equation holds true for problems of water flow in unsaturated sandy soils. This is shown through good agreement between computation results and data obtained from a physical model. Fine sand was used in the model, and changes in the water content, Θ, were measured with Am 241. Good results were obtained upon assuming the boundary condition along the supply time to be in the form of the x-derivative of Θ. It was also found that the widely accepted boundary condition, namely that water content is constant at the supply boundary, can bring about ennoneous conclusions. Good efficiency was achieved in the computations upon the assumption of a time-variable increment δt, which can be determined with a criterion derived through numerical experiments. All computations were performed on a Polish computer, the Odra 1204.
Electromechanical behavior of carbon fiber

Carbon fibers are widely used as a reinforcement in structural composites. The use of these fibers that are already in the composite for strain sensing eliminates the need for strain gages, optical fibers or other sensors, thus decreasing cost and improving durability. For this purpose, the electromechanical behavior (change in DC electrical resistivity upon strain) of the fibers was investigated. A single bare carbon fiber increases its electrical resistance (not resistivity) reversibly upon tension due to changes in dimensions, such that the gage factor (fractional change in resistance per unit strain) in +2. A single carbon fiber embedded in epoxy (a common matrix) has its volume electrical resistivity increased by 10% after curing at 180°C and subsequent cooling of the epoxy, due to the compressive residual stress resulting from the thermal contraction mismatch between fiber and epoxy. Subsequent tension of the embedded fiber at its two exposed ends decreases the residual stress and causes the fiber resistivity to decrease back to its value before embedding, such that the resistivity decrease is reversible, with gage factor -17. Excessive tension causes the resistivity of the fiber to increase, due to damage. Thus, carbon fiber in epoxy is a sensitive piezoresistive strain sensor.
Boundary Friction of Aromatic Self-Assembled Monolayers: Comparison of Systems with One or Both Sliding Surfaces Covered with a Thiol Monolayer

The boundary friction of three aromatic thiol monolayers with different packing densities on gold was studied with friction force microscopy. The friction of each monolayer was measured against unfunctionalized silicon tips and thiol-functionalized gold-covered tips. The experiments were done in ethanol to significantly reduce the tip−substrate adhesion and therefore the dependence of the friction force on contact area. This allowed a direct, quantitative comparison of load- and velocity-dependent friction with tips of different radii. In close-packed systems, the friction force was lower when both surfaces were covered with a monolayer, and plateaus in the friction force vs velocity curves appeared at higher velocity, suggesting a more fluidlike sliding. A transition in the monolayers at high loads was found to be dependent on the tip radius and appeared at higher average pressure for more close-packed systems but did not depend on whether the system contained one or two monolayers.
Do Bridging Water Molecules Dictate the Structure of a Model Dipeptide in Aqueous Solution

Chi-Duen Poon and Edward T. SamulskiDepartment of ChemistryUniVersity of North Carolina-Chapel HillVenable and Kenan Laboratories CB 3290Chapel Hill, North Carolina 27599-3290Christoph F. Weise and James C. Weisshaar*Department of Chemistry, UniVersity of Wisconsin-Madison1101 UniVersity AVenue, Madison, Wisconsin 53706-1396ReceiVed NoVember 9, 1999ReVised Manuscript ReceiVed April 24, 2000Model dipeptides provide the basic elements of secondarystructure (flexible backbone dihedral angles
An Investigation of the Si(111) 7×7 Surface Structure by RHEED

A clean Si(111) surface showing a 7×7 superlattice structure has been investigated in detail by RHEED with changes of azimuthal angle, glancing angle, and surface temperature. For the 7×7 structure, the mean intensity distribution of the reciprocal lattice rods was estimated from the intensity analysis of various RHEED patterns. A Patterson function was calculated using the mean intensity distribution. A new structural model which satisfies the Patterson function has been obtained. This model contains some scattering matter arranged in a regular triangular form with side 2a, a being the size of the substrate unit mesh. The intensity distributions calculated from this model agreed well with that obtained from RHEED and LEED patterns.
Analysis of a surface-normal coupled-quantum-well modulator at 1.55 um

We report on the design and analysis of a surface-normal coupled-quantum-well (CQW) electro-absorption modulator (EAM) using a simulation software APSYS. The modulator is designed as a p-i-n diode operating at 1.55 um, in which the CQW structure is composed of InGaAs-InAlAs. In this paper, detailed analysis of the internal device physics is investigated, which includes the transition energy and the square of the normalized overlap integrals between confined energy levels for electrons and holes. This analysis reveals the mechanisms in the device that are responsible for the redshift of the absorption spectra for achieving an operating wavelength at 1.55 um, which, in turn, provides researchers with insight in the high performance modulators design. The analysis also explains the dependence of the absorption spectra on wavelength and bias voltage. The simulation model self-consistently solves for wavefunctions and the corresponding quantum states energies and then used for absorption spectra calculations within the 2D/3D drift-diffusion framework.
Solubilities of sub- and supercritical carbon dioxide in polyester resins

In supercritical carbon dioxide (CO2) assisted polymer processes the solubility of CO2 in a polymer plays a vital role. The higher the amount of CO2 dissolved in a polymer the higher is the viscosity reduction of the polymer. Solubilities Of CO2 in polyester resins based on propoxylated bisphenol (PPB) and ethoxylated bisphenol (PEB) have been measured using a magnetic suspension balance at temperatures ranging from 333 to 420 K and pressures up to 30 MPa. An optical cell has been used to independently determine the swelling of the polymers, which has been incorporated in the buoyancy correction. In both polyester resins, the solubility of CO, increases with increasing pressure and decreasing temperature as a result of variations in CO, density. The experimental solubility has been correlated to the Sanchez-Lacombe equation of state.
Synthesis of multiple shaped gold nanoparticles using wet chemical method by different dendritic peptides at room temperature

Gold nanoparticles of various shapes including pentagonal, hexagonal, prismatic, branched (multipods), spherical and oval have been prepared by using different generations of peptidic dendrons as templates at room temperature without adding any external reducing or stabilizing agents. Each peptide based dendron molecule (G1, G2 or G3) contains a redox active tyrosine (Tyr) moiety and a free –NH2group at the N-terminus and as a result of that each peptide-dendron molecule can be used to reduce AuCl4− to Au0 and stabilize the nascent gold nanoparticles (GNPs) by the NH2group present in the molecule at room temperature. Not only the shapes but also the sizes of these particles can be tuned by using this chemical methodology involving different peptidic dendrons in water-methanol (4:1) at pH 11. The first generation dendritic peptide produces various shaped GNPs, while the second-generation peptide-dendron molecule leads to the exclusive formation of hexagonal gold nanoparticles and the third generation dendritic peptide gives rise to branched nanoparticles at a certain dendron concentration (5.88 × 10−6 M). In this procedure no external reducing agents or stabilizing agents nor relatively high temperature are required to produce various anisotropic gold nanoparticles. Nanoparticles with different shapes exhibit their characteristic surface plasmon resonance peaks. TEM images vividly demonstrate the specific morphology of gold nanoparticles with different shapes obtained by using different generations of peptide-based dendrons. Corresponding dark field luminescence spectra provide an insight into the shape dependence of the optical properties.
Modeling storm-water runoff quantity and quality from marine drydocks

Storm-water runoff from a floating marine drydock can be a major source of pollution for the waterway in which the drydock is located. Significant amounts of pollutants build up over drydock surfaces because of intensive industrial activity. During periods of rainfall these pollutants can be washed off and quickly transported into the receiving water. In this study, a mathematical model has been developed to simulate the quantity and quality of storm-water runoff from marine drydocks. The mathematical model is based on the two-dimensional kinematic-wave and convective transport equations for total suspended solids. An empirical formula is used to model the wash-off process. An implicit finite-difference scheme is employed to solve the governing equations of the model numerically. In support of the modeling effort, the quantity and quality of storm-water runoff from a private drydock was monitored under actual rainfall-runoff conditions. The samples collected were analyzed in the laboratory to determine the pollutant loading of the runoff, and these data were subsequently used to calibrate and verify the mathematical model.
Synthesis and characterization of polystyrene/poly(4‐vinylpyridine) triblock copolymers by reversible addition–fragmentation chain transfer polymerization and their self‐assembled aggregates in water

Reversible addition–fragmentation chain transfer polymerization (RAFT) was developed for the controlled preparation of polystyrene (PS)/poly(4-vinylpyridine) (P4VP) triblock copolymers. First, PS and P4VP homopolymers were prepared using dibenzyl trithiocarbonate as the chain transfer agent (CTA). Then, PS-b-P4VP-b-PS and P4VP-b-PS-b-P4VP triblock copolymers were synthesized using as macro-CTA the obtained homopolymers PS and P4VP, respectively. The synthesized polymers had relatively narrower molecular weight distributions (Mw/Mn < 1.25), and the polymerization was controlled/living. Furthermore, the polymerization rate appeared to be lower when styrene was polymerized using P4VP as the macro-CTA, compared with polymerizing 4-vinylpyridine using PS as the macro-CTA. This was attributed to the different transfer constants of the P4VP and PS macro-CTAs to the styrene and the 4-vinylpyridine, respectively. The aggregates of the triblock copolymers with different compositions and chain architectures in water also were investigated, and the results are presented. Reducing the P4VP block length and keeping the PS block constant favored the formation of rod aggregates. Moreover, the chain architecture in which the P4VP block was in the middle of the copolymer chain was rather favorable to the rod assembly because of the entropic penalty associated with the looping of the middle-block P4VP to form the aggregate corona and tailing of the end-block PS into the core of the aggregates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1017–1025, 2003
Gold Nanoparticles Linked by Pyrrole- and Thiophene-Based Thiols. Electrochemical, Optical, and Conductive Properties

A series of new alkyl-substituted pyrrole, bithiophene, and terthiophene thiols, terthiophene and sexithiophene dithiols, and polythiophene polythiol have been synthesized. The compounds form self-assembled monolayers on gold with high surface coverages generally in the range (2–4) × 10−10 mol cm−2 as indicated by cyclic voltammetry and UV–vis spectroscopy. The thiols were reacted with 5 nm gold nanoparticles in toluene to form monodisperse, stable, and soluble thiol-capped gold clusters with the same gold core diameter, which were oxidatively coupled electrochemically (in solution or as films) and chemically (with iodine) to polymeric gold clusters. The dithiols (including ethanedithiol) and the polythiol formed analogous polymeric structures via layer-by-layer alternation with gold nanoparticles on gold-modified ITO and glass surfaces. The new materials were investigated by cyclic voltammetry, UV–vis and FTIR spectroscopy, and conductivity. The capped gold clusters display conductivities in the range 10.
Sum Combination Harmonics in Four-Pulse ESEEM Spectra. Study of the Ligand Geometry in Aqua-Vanadyl Complexes in Polycrystalline and Glass Matrices

Abstract Structural differences in the vanadyl pentaaqua complex in two different matrices, a frozen glassy water solution and a polycrystalline Tutton salt, were investigated using the recently designed one dimensional four-pulse electron spin-echo envelope modulation (ESEEM) experiment. The four-pulse ESEEM spectrum consists of the basic nuclear frequencies, ν α and ν β , of the ligands′ protons along with their sum combination harmonics, (ν α + ν β ). This particular example demonstrates the potential of this new experiment which lies in the generation of highly resolved combination harmonics from which information regarding the hyperfine and quadrupole interactions can be derived. While the combination lines in the two-pulse ESEEM spectra of the polycrystalline sample suffered from low resolution due to a relatively short T 2 , highly resolved peaks were observed in the four-pulse ESEEM spectra since in this experiment T 1 dominates the echo decay rather than T 2 . Orientation-selective four-pulse ESEEM experiments were performed under conditions that optimize the intensities of the sum combination harmonics. Aqua complexes with H 2 O and D 2 O were studied and clear differences in the Fourier transform ESEEM spectra of the two matrices, not detected previously by electron-nuclear double-resonance spectroscopy or two-pulse ESEEM, were evident. The analysis of the spectra was done by simulating the FT-ESEEM spectra of both the H 2 O and the D 2 O complexes. For this purpose, an analytical expression describing the four-pulse ESEEM for I = 1 was derived, taking into account the 2 H quadrupole interaction as a first-order correction to the nuclear frequencies. The simulations showed that the positions and orientations of the ligands in VO 2+ (H 2 O) 5 and VO 2+ (D 2 O) 5 are somewhat different in the frozen glassy solution and in the crystalline matrix of the Tutton salt.
Voltammetric Characterization of the Ferrocene|Ferrocenium and Cobaltocenium|Cobaltocene Redox Couples in RTILs

Ferrocene, Fc, and cobaltocenium hexafluorophosphate, CcPF6, have been recommended for use as internal reference redox couples in room-temperature ionic liquids (RTILs), as well as in more conventional aprotic solvents. In this study, the electrochemical behavior of Fc and CcPF6 is reported in eight commonly used RTILs; [C2mim][NTf2], [C4mim][NTf2], [C4mim][BF4], [C4mim][PF6], [C4mim][OTf], [C4mim][NO3], [C4mpyrr][NTf2], and [P14,6,6,6][FAP], where [Cnmim]+ = 1-butyl-3-methylimidazolium, [NTf2]- = bis(trifluoromethylsulfonyl)imide, [BF4]- = tetrafluoroborate, [PF6]- = hexafluorophosphate, [OTf]- = trifluoromethylsulfonate, [NO3]- = nitrate, [C4mpyrr]+ = N-butyl-N-methylpyrrolidinium, [P14,6,6,6 ]+ = tris(n-hexyl)-tetradecylphosphonium and [FAP]- = trifluorotris(pentafluoroethyl)phosphate, over a range of concentrations and temperatures. Solubilities and diffusion coefficients, D, of both the charged and neutral species were determined using double potential-step chronoamperometry, and CcPF6 (36.5−450.0 mM.