Miracle-dz/UniFAR-FTUs huggingface dataset:
Fluorescence correlation spectroscopy considering the effect of photobleaching

In fluorescence correlation spectroscopy (FCS), the fluorescence intensity decay curve is used to calculate the correlation time, which characterizes the diffusion feature of the molecules. However, photobleaching, an unavoidable phenomenon that happened during fluorescence excitation, would result in fluorescence decay, and thus cause error in the calculation of the correlation time and the diffusion coefficient. To compensate this effect, a probability factor is introduced. This factor describes the probability at which a molecule is photobleached by the excitation laser during fluorescence excitation. By selecting the right value of the photobleaching factor, the effect of photobleaching on the FCS measurement can be removed.
THE PREPARATION OF LIDOCAINE

In this experiment, which is intended for the introductory organic laboratory, the widely used local anesthetic Lidocaine is synthesized in two steps from 2,6-dimethylaniline. In the first step, the amine is acylated with chloroacetyl chloride. In the second step, the amide is subjected to nucleophilic substitution by diethylamine to give the final product with an overall yield of 71% based on 2,6-dimethylaniline. I have used this experiment in my organic class for several years with excellent results. Average students can isolate the crude product in less than three hours.
Physical property exploration of highly oriented V2O5 thin films prepared by electron beam evaporation

Highly oriented vanadium pentoxide (V2O5) thin films were grown by electron beam (EB) evaporation on glass substrates at 473 K. V2O5 thin films were coated with various thicknesses (≈800–1200 nm) by varying the distance from the source and substrates. The influence of film thickness on its physical properties was deeply studied by various characterization techniques. XRD studies were performed to investigate the structural confirmation and preferential lattice orientation of EB evaporated films. The Voigt profile method was used to estimate the microstructural parameters and to elaborately discuss its dependency on film thickness. SEM micrographs perceived that the prepared films were nearly homogeneous with densely packed morphology. AFM topographical images depicted the nanograins on the surface of the films. Raman spectra confirmed the formation of the α-V2O5 polymorph without secondary phase formation. From the optical absorption data, the indirect optical band gap ‘Eg’ was found to be 2.36 eV for V2O5 thin film with higher thickness. Optical constants such as refractive index (n), extinction coefficient (k), optical conductivity (σ) and dielectric constants (e) were evaluated using an approximation protocol developed from well recognized procedures using the data obtained from the UV-Vis spectroscopic technique. The luminescence property variations were observed by photoluminescence (PL) spectroscopy and it has elucidated the role of film thickness in the EB evaporated V2O5 films. The Hall mobility and carrier density were found to increase with film thickness.
Effect of confinement on chemical reaction equilibria: The reactions 2NO⇔(NO)2 and N2+3H2⇔2NH3 in carbon micropores

We report reactive Monte Carlo (RMC) simulations of reaction equilibria for both the nitric oxide dimerization and the ammonia synthesis reactions. We have applied the RMC technique to both a single bulk phase and also to a two-phase system, composed of the bulk gas and a slit-shaped pore, with pore parameters chosen to model activated carbon fibers. We achieve close agreement with the experimentally measured conversions of nitric oxide and ammonia in the bulk phase. Both reactions involve a stoichiometric decrease in mole number, which should cause the yield of each to be enhanced by the increased density within the pore phase. We show that the effect of confinement on the yield of both reactions is significant, and is particularly dramatic for the nitric oxide reaction; in addition, the ammonia synthesis reaction is affected by the selective adsorption of nitrogen over hydrogen in the pore under certain conditions.
Electrochemical and chemical insertion/deinsertion of magnesium in spinel-type MgMn2O4 and lambda-MnO2 for both aqueous and non-aqueous magnesium-ion batteries

By using both chemical and electrochemical methods, magnesium has been reversibly removed from MgMn2O4 (s.g. I41/amd) with appropiate texture to form single-phase and nanocrystalline λ-MnO2 (s.g. Fdm). Cubic λ-MnO2 is not stable after annealing in both air and Ar atmospheres. The oxidation of Mn(III) to Mn(IV) eliminates the tetragonal distortion of the spinel-type lattice, but λ-MnO2 is more effectively obtained when powdered MgMn2O4 has a large specific surface area and a small particle size. In an aqueous solution of a magnesium salt, λ-MnO2 is formed by galvanostatic charge of MgMn2O4 and continuous Ar-flowing for removing oxygen from the solution. Starting from λ-MnO2, the tetragonal structure of MgMn2O4 and the cubic structure of LiMn2O4 are generated by electrochemical cycling in aqueous solutions containing salts of magnesium and lithium, respectively. In an aqueous solution cell, this material exhibits a reversible capacity of about 150 mA h g−1 and can be used in magnesium-ion batteries demonstrating it to be competitive against their lithium counterparts. In the absence of metallic Mg, the use of carbonate-based solvents can be a good choice for veritable non-aqueous magnesium-ion batteries, for example using positive electrode materials like MgMn2O4 (magnesium-ion source) and negative electrode materials like V2O5. In non-aqueous solvents (ethylene carbonate–diethyl carbonate mixture), the cubic phase λ-MnO2 is not formed, the tetragonal structure of MgxMn2O4 is preserved and its lattice cell is contracted.
Arsenite Determination in Phosphate Media at Electroaggregated Gold Nanoparticle Deposits

Compared to bulk gold, highly reactive mesoporous gold film deposits are prepared on a boron-doped diamond electrode surface. An electroaggregation process causing 5 nm diameter gold nanoparticles to deposit cathodically from aqueous solution is implemented to control the amount of mesoporous gold at the electrode surface. The resulting electrode surface is characterized by electron microscopy and by cyclic voltammetry. The reactivity of the electroaggregated gold deposit towards arsenite is investigated in nitric acid media and in neutral phosphate buffer media. Three processes consistent with (i) cathodic deposition of arsenic metal (As(III) -> As(0)), (ii) anodic stripping (As(0) -> As(III)), and oxidation of arsenite (As(III) -> As(V)) are observed and shown to shift in potential with approximately 58 mV per pH unit (Nernstian at 20 degrees C). Improved anodic stripping voltammetry responses for solutions of arsenite(III) in 0.1 M HNO3 and in 0.1 M phosphate buffer solution are observed as the gold nanoparticle deposition time is increased. Typical detection limits of LOD(3 sigma) = 30 ppb in nitric acid and LOD(sigma) = 1 ppb in phosphate buffer (pH 7) are observed.
Trickle‐bed reactors: Tracer study of liquid holdup and wetting efficiency at high temperature and pressure

Liquid holdup and wetting efficiency were measured by means of stimulus-response (pulse-tracer) experiments in a trickle-bed reactor, packed with a commercial hydrodemetallization catalyst, and operated at 10 MPa and 330–370°C, with a superficial liquid velocity of 1.4 to 8.3 × 10−4 m/s. The total liquid holdup was obtained from the first moments, and the external wetting efficiency from the second moments, of the response curves. The dynamic holdup obtained from the total holdup lies within the range described by existing correlations, but wetting efficiency is significantly lower than literature data obtained at ambient conditions. On a mesure la retention du liquide et l'efficacite du mouillage par des experiences stimulus-reponse (traceur-impulsion) dans un reacteur a lit ruisselant, garni avec un catalyseur commercial d'hydrodemetalisation, et fonctionnant a 10 MPa et a 330–370°C, avec une vitesse liquide superficielle de 1,4 a 8,3 × 10−4 m/s. On a obtenu la retention liquide totale des premiers moments de la courbe des reponses et l'efficacite du mouillage externe des deuxiemes moments. La retention dynamique obtenue a partir de la retention totale se situe dans la gamme couverte par les correlations existantes, mais l'efficacite du mouillage est nettement inferieure aux donnees publiees aux conditions ambiantes.
Indirect-gap AlxGa1-xAs and its similarity to GaP

We report on luminescence, transmission and luminescence excitation measurements on indirect-gap AlxGa1-xAs in the composition range 0.42<or=x<or=0.86. The phonon coupling strength in transitions of bound excitons is investigated and found to be dependent on AlAs mole fraction and on the chemical species of the binding impurity. We find binding energy values of 35.5+or-5.5 meV for x=0.42 and 50.0+or-5.5 meV for x=0.86. The recombination of indirect-gap free excitons is strongly influenced by a so-called 'camel's back structure' ( Delta =349 meV, delta =5.5 meV, zeta =0.092 for x=0.42) within the lowest conduction band near the zone boundary X. The exciton binding energy amounts to 20+or-3 meV, much higher than reported recently in literature, and much higher than computable using a simple hydrogen model for the exciton. Temperature-dependent luminescence measurements-in the temperature range 4.2 K<or=T<or=300 K-yielded a reliable relation for the temperature dependence of the indirect excitonic gap at an AlAs mole fraction of x=0.42. From temperature-dependent measurements the binding energy of the sulphur donor was evaluated to be 95+or-9 meV in Al0.75Ga0. 25As, being representative of AlAs-rich material. This value, more than twice that computable from a simple effective-mass model, has to be seen as a further strong hint at a pronounced anisotropy within the lowest conduction band at the X point of the Brillouin zone. Because the band structure data of AlAs and indirect-gap AlxGa1-xAs are very similar to those of the well known binary compound GaP, we consequently use the detailed knowledge on near-gap electronic states in this material to describe our experimental findings.
Tribology of Shearing Polymer Surfaces. 2. Polymer (PnBMA) Sliding On Mica

Quantitative friction force measurements were made using a Surface Forces apparatus (SFA) modified for friction studies of a smooth poly(n-butyl methacrylate) (PnBMA) surface sliding on a stationary mica surface, and the results are compared with those of the complementary system (ref 1) of mica sliding on a stationary polymer surface. The results indicate that qualitatively and quantitatively different tribological behavior may be expectedas manifested by smooth or stick-slip sliding, high or low steady-state friction stresses, transient effects such as stiction, and surface deformations and wearfor such “asymmetric” surfaces depending on whether the sliding or stationary surface carries the lubricant or polymer layer, on whether the motion is continuous in one direction or cyclic (back and forth), and on the area of the contacting junctions. None of these effects would arise if the friction forces were determined solely by the instantaneous load (pressure) and velocity (shear rate) of the shearing junct.
Mass Transfer Resistance Analysis of L-Tryptophan Extraction in an Emulsion Liquid Membrane System

The extraction of L-tryptophan with an emulsion liquid membrane containing di-2-ethylhexy phosphoric acid as a carrier, Span 80 as a surfactant, kerosene as a solvent, and hydrochloric acid solution as an internal phase stripping reagent, was studied. The effects of external phase pH, carrier concentration, internal stripping reagent concentration, and external initial solute concentration on the mass transfer flux were examined. The fractional resistances of external phase diffusion and emulsion globule diffusion to the overall process were defined and calculated by the proposed model. Thus, the rate-controlling steps for the overall process were quantitatively identified. For higher external phase pH and/or higher carrier concentration as well as lower external initial solute concentration, the overall process is mainly determined by the external phase diffusion. On the other hand, for lower external pH and/or lower carrier concentration, the emulsion diffusion is a rate-controlling step. However, in the majority of cases, the overall process is governed by the combined effects of both the external phase diffusion and the emulsion globule diffusion. Compared with the external phase pH and carrier concentration, the concentrations of internal stripping reagent and external initial solute are unimportant factors determining the overall process.
Photovoltaic module calibration value versus optical air mass: the air mass function

So‐called “air mass functions” of photovoltaic modules are used to approximate the effects of spectral responsivity and to correct short‐circuit current to or from a reference condition. These empirical functions are determined from outdoor measurements with test modules mounted on two‐axis solar trackers and then calculated from plots of normalized calibration value (short‐circuit current divided by total irradiance) versus optical air mass. Because they are incorporated into a number of photovoltaic system modeling and sizing software programs, the accuracy of the functions has direct implications for system costs. We discuss the assumptions associated with these functions that are generally not considered or ignored, and study their variability with respect to atmospheric constituents. The variability study included a 6‐month outdoor measurement on a crystalline‐Si module and a software simulation of the same module using a solar spectral irradiance model. We conclude that air mass functions depend on the measurement location and time, and therefore are not unique to a particular device. Also, using these functions introduces two distinct errors, the magnitudes of which are unknown without knowledge of spectral irradiance conditions. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Arsenic adsorption on Ti-pillared montmorillonite

BACKGROUND: Arsenic pollution in drinking water has been found in most countries. Arsenate (As(V)) and arsenite (As(III)) are two major forms of inorganic arsenic species, and the latter is the more toxic. The removal of arsenic ions from water has attracted increased attention, and therefore further understanding and development of techniques for removal of arsenic ions are required. RESULTS: Adsorption of arsenate and arsenite from aqueous solutions using Ti-pillared montmorillonite (Ti-MMT) was investigated as a function of contact time, pH, temperature, coexisting ions, and ionic strength. The adsorption of both arsenate and arsenite were temperature and pH dependent, indicating different adsorption mechanisms. The effect of coexisting ions on the adsorption was also studied and, among the ions investigated, only phosphate had a noticeable influence on the adsorption of arsenate, while the effect of other ions was negligible. A pseudo-second-order chemical reaction model was obtained for both arsenate and arsenite; adsorption isotherms of arsenate and arsenite fitted the Langmuir and Freundlich isotherm models well. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to study the nature of surface elements before and after adsorption. CONCLUSIONS: This work demonstrates that Ti-pillared montmorillonite is an efficient material for the removal of arsenate and arsenite from aqueous solutions. Experimental parameters such as contact time, solution pH, temperature, initial concentration, coexisting ions, and ionic strength have been optimized. Copyright © 2010 Society of Chemical Industry
Laser-induced damage in beta-barium metaborate

Laser‐induced damage in beta‐barium metaborate (BBO) has been investigated at the wavelengths of 1064, 532, and 355 nm. The single‐shot bulk damage threshold of BBO is 50 GW/cm2 at 1064 nm, 48 GW/cm2 at 532 nm, and 25 GW/cm2 at 355 nm. Damage by multiple pulse irradiation has also been studied and the probabilistic nature of the damage is discussed. Brief comments are also made on the morphology of the damage.
Preparation of ZnO nanorods on cellulose fiber paper and their charge‐generating application for waste paper recycling

Zinc oxide (ZnO) nanorod arrays (NRAs) were well integrated on the cellulose fibers (CFs) of waste paper via a facile hydrothermal method. By mechanically blending the waste paper with de‐ionized water, abundant CFs were obtained and used as a sufficient platform for integrating ZnO NRAs. After coating a thin ZnO seed layer onto the surface of CFs and subsequent thermal treatment, the ZnO NRAs were densely grown, exhibiting high crystallinity and good photoluminescence properties. Their sizes were readily controlled by changing the concentration of the growth solution. To test the feasibility of an energy harvesting application using the prepared samples, the piezoelectric charge generation was explored under an external pushing force for the fabricated devices with polydimethylsiloxane‐shielded ZnO NRAs on CFs for good contact to two electrodes (i.e., gold and indium tin oxide). This nanotechnology of recycling waste paper could be considered as a promising candidate for implementation in cost‐effective and environment‐friendly advanced materials and energy production. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction Between Cadmium and Lead and the Effects of These on the Concentration of Zinc and Manganese in Sunflower

The pollution of soil by heavy metals is considered to be quite a big problem in many areas ofthe world. To limit the accumulation of lead and cadmium from soil in the products, a correct understanding ofthe characteristics and specifications of the translocation of cadmium and lead is necessary. In order to evaluatethe effects of cadmium and lead interaction on zinc and manganese concentration, three levels of cadmium (0,100 and 200 mg/kg), and three levels of lead (0, 200 and 400mg/kg) were tested on a sunflower cultivar SHF81-85 in a factorial experimental design with three replications. The results showed that cadmium has increasedthe cadmium and lead concentration in the shoot and root, while the effects of lead, were only significant on theconcentration of lead in the shoot, and the concentration of both cadmium and lead in the root (p<0.05). Cadmium and lead revealed a preventing effect on zinc and manganese concentration in the root and shoot ofthe plant. More investigations at field conditions are recommended.
Probing ballistic microdrop coalescence by stroboscopic small-angle X-ray scattering

The coalescence of ballistic microdrops has been explored by stroboscopic synchrotron radiation microbeam small-angle X-ray scattering (μSAXS). About 80 μm diameter microdrops generated by a drop-on-demand inkjet system travelled at ∼1.7 m/s through a ∼1 μm X-ray beam. Microdrops of cytochrome C and acetate buffer solutions were merged in order to study the pH driven conformational change. μSAXS patterns were accumulated on a pixel detector, which was activated for a few μsec during the transit time of each microdrop through the microbeam. Local probing of the merging microdrops reveals the internal protein solution flow.
Viscosities of p-Xylene, Acetic Acid, and p-Xylene + Acetic Acid at (313.15 to 473.15) K and (0.10 to 3.20) MPa : Determined by the Rolling-Ball Method

Experimental liquid viscosities of pure compounds and their mixtures are needed for the design of chemical processes in heat and mass transfers or fluid mechanics. This paper is about partial work supported by SINOPEC (China Petroleum & Chemical Corporation). The results are related to the design calculation of synthesis of purified terephthalic acid (PTA). At temperature (313.15 to 473.15) K, the viscosities of pure p-xylene, pure acetic acid, and the p-xylene + acetic acid binary system of different concentrations were determined by a rolling-ball viscometer at pressures (0.10 to 3.20) MPa. Then, the viscosity data were fitted by a correlation equation. The AAD of the correlation is 1.21 %.
Very low threshold current density 1.5 μm GaInAs/AlGaInAs graded‐index separate‐confinement‐heterostructure strained quantum well laser diodes grown by organometallic chemical vapor deposition

Very low threshold current densities of 200 and 400 A/cm2 were obtained in 1.5 μm GaInAs/AlGaInAs tensile and compressive strained‐layer quantum well laser diodes (SL‐QW LDs), grown by organometallic chemical vapor deposition, with continuously graded‐index separate‐confinement‐heterostructure. The differential quantum efficiency of SL‐QW LDs showed less sensitive to temperature in contrast to that of a lattice matched QW LD. This is attributed to the decrease of intervalence band absorption due to the strain‐induced reduction in the valence band density of state. The polarization of output power for a tensile SL‐QW LD showed transverse magnetic (TM) mode, while that for a lattice matched and a compressive SL‐QW LDs showed transverse electric (TE) mode.
Polyethylene glycol-400/H3PO2: an eco-friendly reductive system for the synthesis of selanylesters

An alternative green method was described for the synthesis of selanylesters by reactions of acyl chlorides with arylselenols, generated in situ by reaction of diaryl diselenides with hypophosphorous acid (H3PO2) using polyethylene glycol-400 (PEG-400) as the solvent. These reactions proceeded efficiently at room temperature under N2 using a range of acyl chlorides and diaryl diselenides, both containing electron-withdrawing and electron-donating groups, affording the corresponding selanylesters in moderate to excellent yields. Additionally, PEG-400 can be recovered and directly reused for further reactions.
Dense fluid non-equilibria and the Prigogine theory

The theory of Prigogine is applied to the deduction of the molecular structure of a simple dense fluid not in equilibrium, described in terms of the phase singlet distribution. The intermolecular interaction is assumed to have the form of the sum of constituent pair forces, and the pair force itself is supposed to be composed of a hard core and an extended weak interaction. It is shown how the Rice-Allnatt equation can be derived in this way, but that the natural development of the theory of the time evolution of the singlet distribution is such as to lead as a first approximation to the equation recently given independently by Popielowski, Rice and Hurt. An improved equation for the singlet distribution is derived, in § 8, and some comments are made about the present standing of the theory in its application to dense fluids.
A New Limit on the Electron Electric Dipole Moment: Beam Production, Data Interpretation, and Systematics

The charge distribution associated with an electron has surprising implications for a number of outstanding mysteries in physics. Why is the universe made out of matter versus anti-matter, instead of both equally? What new particles and interactions lie beyond the current reach of accelerators like the LHC? Models which propose answers to these questions, such as Supersymmetry, tend to predict a small, yet potentially measurable, asymmetric interaction between an electron and an electric field, characterized by an electric dipole moment (EDM). Despite over six decades of experimental searching, no EDM of any fundamental particle has ever been measured; however, these experiments continue to provide some of the most stringent limits on new physics. Here, we present the results of a new search for the electron EDM, de = (−2.1 ± 3.7stat ± 2.5syst) × 10−29 e cm, which represents an order of magnitude improvement in sensitivity from the previous best limit. Since our measurement is consistent with zero, we present the upper limit of |de| < 8.7 × 10−29 e cm with 90 percent confidence.