Miracle-dz/UniFAR-FTUs huggingface dataset:
Comparison of the FT-IR Mapping and Imaging Techniques Applied to Polymeric Systems

Two Fourier transform infrared (FT-IR) spectrometers with microspectroscopic capabilities—one equipped with a focal plane array (FPA) mercury-cadmium-telluride (MCT) detector (imaging) and the other a single-element MCT detector (mapping)—are compared. Two samples, a one-dimensional diffusion system and a two-dimensional phase-separated system, were studied with both analytical tools. Diffusion regions and concentration gradients were determined in the diffusion sample. Phase-specific chemical composition data were obtained in the phase-separated sample. The utility of each instrument for specific cases and their respective limitations are illustrated. It is shown that the FPA system has the ability to sample a large sample area with high spatial resolution in a short time without adverse diffraction effects. Because of this very rapid sampling, many dynamic processes can be studied which are otherwise poorly monitored by the point-by-point mapping technique. The spatial resolution achievable, the quality of data obtained [signal-to-noise ratio (SNR)], and temporal resolution between mapped areas are intimately connected in the mapping system. However, the imaging systems have a fixed spatial resolution (dependent on the optics and detector) and the SNR considerations determine temporal resolution. However, it was also shown that by aperturing to a localized region, the single-element detector system is able to arrive at phase concentration information more rapidly, with less cumbersome processing and with higher SNRs than is possible with the current FPA technology. The chemical information obtained from both instruments is, within a small experimental error, identical. This work demonstrates what can be accomplished with each analytical FT-IR instrument, and serves as a comparative study to demonstrate the value of each analytical tool in specific situations.
CO2 Adsorption and Desorption on MgO/Al2O3: An In Situ Diffuse Reflection Infrared Fourier Transform Spectroscopy (DRIFTS) Study

The adsorption and desorption of CO2 on MgO/Al2O3 were investigated by in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) combined with the method of curve-fitting analysis. The spectroscopic results indicate that there are three chemisorbed surface species formed on the MgO/Al2O3, i.e., free carbonate ion, bridged carbonate, and bidentate carbonate species, which correspond to the peaks at 1675, 1403, and two peaks at 1610 and 1340 cm−1, respectively, when the sample was exposed in CO2 flow at 130 °C. The quantification analysis of the spectra during CO2 adsorption and desorption shows that the formation and desorption rates of all surface species are coverage dependent. Among the three species, the bridged carbonate shows the highest speed of formation and desorption, indicating that this type of species may be beneficial to CO2 capture and release. It should also be noted that the contribution of support Al2O3 to CO2 capture is negligible. This study may help us to understand the interaction between CO2 and metal oxides and thus to give more insights into CO2 capture using solid sorbents.
Graphite-Furnace Atomic Absorption Spectrometric Method for Direct Determination of Iron and Zinc in Solid Rice Samples

A method for the direct determination of iron and zinc traces in solid rice samples using graphite-furnace atomic absorption spectrometry is proposed. Samples are placed in a graphite tube with a platform, and are determined from integrated absorbance measurements that are interpolated on calibration graphs obtained from aqueous standards of the two metals. The working conditions used allow iron and zinc to be determined at concentrations down to 10 ug g^−1 (0.001%) in solid rice samples with a relative standard deviation of 6–10%.
Poly(vinylpyrrolidone) – A Versatile Polymer for Biomedical and Beyond Medical Applications

The high versatility of poly(vinylpyrrolidone) (PVP) can be explained by its diverse properties including its solubility in water and in a broad range of liquid media, high chemical and thermal resistance, and unique wetting, binding, and film-forming properties. Thanks to biocompatibility, absence of toxicity and high capacity to form interpolymer complexes, PVP is widely used for designing materials for different applications, such as biomaterials for medical and nonmedical uses. This review summarizes a vast diversity of applicative examples showing the tremendous opportunities for future research and developments of PVP based biomaterials. GRAPHICAL ABSTRACT
Combined Brownian Dynamics and Spectral Simulation of the Recovery of Polymeric Fluids after Shear Flow

The constrained recovery of polymeric fluids following cessation of steady shear flow is studied using linear bead−spring chain models for dilute polymer solutions and the Curtiss−Bird model for polymer melts. Brownian dynamics simulation techniques are combined with a spectral method for solution of the continuum equation of motion. The shear stress required to solve the continuum equation is computed directly from ensemble averages over internal configurations of model molecules, thereby eliminating the need for a closed-form constitutive equation. Simultaneous solution of the equation of motion for actual fluid velocities obviates the linear velocity profile assumption used in previous studies of constrained recoil. For each of the models examined in the present work, a maximum was observed in the overall recovery with increasing steady-state shear rate. These maxima are an inherent consequence of the polymer models' shear thinning behavior but are more pronounced if the assumption of a linear velocity.
Nanoscopic Investigation of the Self-Assembly Processes of Dialkyl Disulfides and Dialkyl Sulfides on Au(111)

The formation of striped phases of dialkyl disulfides and dialkyl sulfides on Au(111) and graphite has been monitored by scanning tunneling microscopy (STM) to investigate differences in adsorption of the sulfide to the gold surface. Striped phases formed by C18H37S- moieties after S−S bond cleavage of dioctadecyl disulfide on the gold surface were observed. On the other hand, self-assembled monolayers (SAMs) of dioctadecyl disulfide and dioctadecyl sulfide adsorbed on a graphite surface displayed long-range, well-ordered monolayers with one striped pattern that shows uniform periodicity as a function of molecular length via nondissociative adsorption. In the case of dioctadecyl sulfide SAMs on gold, molecular ordering was identical in periodicity and pattern to the striped phase of SAMs formed by physisorption on the graphite surface. In addition, the striped phase of dioctadecyl sulfide SAMs formed upon a 22 × √3 surface reconstruction of Au(111) was clearly observed for the first time in the SAM system.
Intermolecular Dynamics of Room-Temperature Ionic Liquids: Femtosecond Optical Kerr Effect Measurements on 1-Alkyl-3-methylimidazolium Bis((trifluoromethyl)sulfonyl)imides†

Using optically heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES) with 40 fs laser pulses, the transient birefringence in the room-temperature ionic liquids (RTILs), 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imides, [Cnmim]NTf2 with n = 2, 4, 5, 6, 8, 10 (C2, C4, C5, C6, C8, C10), has been studied at room temperature and ambient pressure. Near zero delay, the OHD-RIKES response is dominated by the instantaneous electronic response. The nuclear response appears as a shoulder on the electronic response. Between 0 and 1 ps, the nuclear response is dominated by the intermolecular vibrational (nondiffusive) response. For C4, C5, C6, and C8, the 1/e time of the pseudo-exponential tail of the intermolecular response decreases with viscosity, in accord with the hydrodynamic model for vibrational dephasing. Superimposed on the OHD-RIKES response for C4, C5, and C6 is a coherent oscillation with a frequency of ∼140 cm-1. The intermolecular vibrational spectra for these RTILs obt.
Catalytic Cycle of Penicillin Acylase from Escherichia coli: QM/MM Modeling of Chemical Transformations in the Enzyme Active Site upon Penicillin G Hydrolysis

Penicillin acylase from Escherichia coli is a unique enzyme that belongs to the recently discovered superfamily of N-terminal nucleophile hydrolases. It catalyzes selective hydrolysis of the side chain amide bond of penicillins and cephalosporins while leaving the labile amide bond in the β-lactam ring intact. Despite wide applications of penicillin acylase in the industry of β-lactam antibiotics and production of chiral amino compounds, its catalytic mechanism at atomic resolution has not yet been characterized. The complete cycle of chemical transformations of the most specific substrate of the enzyme, penicillin G, leading to formation of 6-aminopenicillanic and phenylacetic acids was modeled following quantum mechanics–molecular mechanics (QM/MM) calculations of the minimum energy reaction profile. The active site residues and the substrate were included in the QM part, and the rest of the system was treated applying molecular mechanics and classical force field parameters. The 3D structures in the en.
Density, sound velocity and refractive index in the water + 1,2-dimethoxyethane system

Density, sound velocity and refractive index of binary mixtures of water + 1,2-dimethoxyethane mixtures were measured over the whole composition range and at the temperature interval from 293.15 to 323.15 K. Obtained density data for the pure components agree, within experimental error, with published values. However, in the case of binary mixtures, strong discrepancies with values calculated from the equation proposed in the literature for this system are found. Excess functions, isentropic compressibility coefficients and thermal expansion coefficients were calculated from experimental data. Partial molar volumes were obtained employing the exponential representation previously proposed by us which shows better results than the usual polynomial approach. Results are discussed on the grounds of the molecular characteristics obtained from Raman and NMR spectroscopy determinations on this system.
Energy deposition and transfer in electron-beam lithography

An analytical electron-resist interaction (ERI) model is developed based on detailed investigation of secondary electron production and binding energy related exposure events. Analysis shows that 80% of the exposure events are directly caused by secondary electrons for 100 keV primary electron energy. The number of secondary electrons and further cascade electrons is 1/20 and 1/300, respectively, of the incoming electrons. An algebraic expression is derived to describe the spatial distribution of the exposure events. The ERI model can be extended to chemically amplified resists.
Kinetics of p-Xylene Liquid-Phase Catalytic Oxidation to Terephthalic Acid

A fractional kinetic model for the liquid-phase oxidation of p-xylene to terephthalic acid catalyzed by cobalt acetate and manganese acetate and promoted by hydrogen bromide was proposed. The developed model parameters were determined in a nonlinear optimization, minimizing the difference between the simulated and experimental time evolution of the product composition obtained in a semibatch oxidation reactor where the gas and liquid phases were well mixed. The experiments included four values of the initial concentration of p-xylene. Further, the effects of the oxygen partial pressure, reaction temperature, catalyst concentration, and promoter concentration on the time evolution of the experimental product distribution and kinetic constants of the developed model were investigated.
Simulation of corona discharge. Negative corona in SF/sub 6/

Negative coronas in SF/sub 6/ under three voltage levels are investigated by Monte Carlo simulation. For the purpose of simulation, the gap between a hyperboloidal needle and a plane is divided into two regions: region I where the electric field is very steep and most electrons and ions are accumulated, and region II the rest of the gap. In region I electron motion is simulated by dividing the region into a number of cells and a small cell size improves the accuracy. The magnitude of current pulse increases with increasing voltage and there appears to be more than one peak in each pulse as observed by experiment. The development of electron avalanches is due to ionization and photoionization in the high field region, while the quenching of the avalanches is due to the space charge field suppression. Also the accumulation of positive and negative ions are displayed in detail. The space charge field distortion is studied and found to increase with increasing applied voltage. >
Particle Size Distribution by Space or Time Dependent Extinction Profiles obtained by Analytical Centrifugation

The particle size distribution of suspensions of fine particles was determined by a photocentrifuge from transmission/extinction profiles. Photocentrifuges provide a useful tool for the characterization and quality control of suspensions. While the variation of the light extinction curves caused by centrifugal segregation allows a qualitative description, a rigorous formulation provides a quantitative characterization. The present work reports on the determination of the particle size distribution using space and time resolved extinction profiles. The particle size distribution is obtained by analyzing the variation of the extinction at any point of the sample over the full centrifugation time or by analyzing the extinction variation over the entire sample length for any centrifugation time span. The advantage of the second method is the potential to save time.
Identification of Atomic Vacancies in Titanium Monoxide by Electron Microdiffraction and Positron Annihilation

Introduction At ambient conditions titanium monoxide, TiOy, with a wide range of homogeneity of the B1 lattice structure is stable only with vacancies on both the titanium and oxygen sublattices. Even for the stoichiometric composition of TiO the vacancy content is large and equal to about 15–16 at. % on the two sublattices [1]. The vacancies can be eliminated only at the very high pressure of 8 GPa and high temperature of 1920 K [2, 3]. The elimination of the vacancies is accompanied by an increase in the lattice constant from 0.41796 to 0.42062 nm [2]. At low temperatures the titanium, the oxygen atoms and the vacancies are ordered and form a superstructure with space group C2/m [4, 5]. In order to understand the stability of the structure with vacancies on both sublattices the electron structure and the charge state of such vacancies has been studied. In this paper electron microdiffraction which yields information about the distribution of lattice vacancies and positron annihilation techniques which are sensitive to the charge state of lattice vacancies were employed.
Electrospun nanofibers: Internal structure and intrinsic orientation

Electrospinning gives rise to polymer nanofibers. The spinning process is characterized by strong deformations of the polymer material taking place during the spinning process and a very rapid structure formation process happening within milliseconds. We were interested in the influence of the peculiar spinning process on the structures of nanofibers. For this purpose, we analyzed the internal structures of nanofibers spun from polyamide-6 and polylactide with an average diameter of about 50 nm. The fibers were partially crystalline, with degrees of crystallinity not significantly smaller than those found for less rapidly quenched and much thicker melt-extruded fibers. The annealing of polyamide fibers at elevated temperatures resulted in a transformation from the disordered γ modification to the more highly ordered α modification, and this again was in close agreement with the response of melt-extruded fibers. The orientation of the crystals along the fiber axis was strongly inhomogeneous: it was, on average, very weak, yet it could be quite pronounced locally. Small elongations of approximately 10% resulted in well-developed homogeneous crystal orientations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 545–553, 2003
Adsorption of Phosphonic Acid at the TiO2 Anatase (101) and Rutile (110) Surfaces

The adsorption of phosphonic acid on the TiO2 anatase (101) and rutile (110) surfaces have been investigated by means of efficient density-functional-based tight-binding calculations. We studied the geometries and adsorption energies of several adsorption models to achieve clarification of the discrepancy in the experimental finding of a preferred binding state. In this paper we show that there are several adsorption structures likely to be present on the specific TiO2 surfaces. Those structures have exclusively a bidentate configuration. They have similar adsorption energies but different geometries. For the monodentate complexes, we find a strong trend of the adsorption geometry relaxing toward the bidentate coordination. Also, they have significantly smaller adsorption energies. Furthermore, we extensively demonstrate the reliability of the SCC-DFTB method for this chemical system, which opens the way for studies of adsorption on more complex titania materials.
Non-Invasive Fermentation Analysis Using an Artificial Neural Network Algorithm for Processing near Infrared Spectra

The feasibility of using Artificial Neural Networks (ANN) to improve the performance of a fibre optic, near infrared (NIR) spectroscopic probe for monitoring fermentation processes was investigated. A miniature diode array spectrometer, operating between 1100 and 1450 nm, was used for on-line, in situ fermentation monitoring by placing a bifurcated fibre bundle inside a fermentation vessel. Non-linearities in the spectral response were complicated by the combined effects of spectral variations in the OH vibrational bands due to temperature fluctuations and pH variation. As the fermentation proceeds interferences from other absorbing molecules and cell masses increase at an exponential rate. The feasibility of accurately predicting both glucose and ethanol concentrations simultaneously during a fermentation process were assessed by applying Partial Least Squares (PLS) and Artificial Neural Networks (ANN) to the NIR spectral data. For a 5% glucose fermentation, a PLS model was able to predict “on-line” concentrations with standard errors of prediction (SEP) of 0.19% for glucose and 0.11% for ethanol. Three separate on-line fermentation experiments were performed in order to determine the possibility of using a model developed from one experiment to predict the concentrations of another experiment. PLS models produced an average SEP of 0.21% when used to predict different fermentation experiments. The ANN algorithm produced an average SEP of 0.13% on the same data.
Immunochromatographic strip development for ultrasensitive analysis of aflatoxin M1

A specific monoclonal antibody against aflatoxin (AF) M1 was prepared by a duo-immunogen immunization strategy. After two immunizations of Balb/c mice with AFB1 keyhole limpet hemocyanin (KLH) conjugates and followed by five subsequent immunizations of AFM–KLH, the mice secreting antibody against AFM1 were selected for cell fusion and a 7C6-H1 cell line was obtained to produce the antibody. The 50% inhibition rate of the prepared antibody was calculated as 0.034 ± 0.002 μg L−1. The anti-AFM1 antibody was characterized with high affinity to AFM1 (1.28 × 109 mol L−1) and low cross-reactivity to related AFs (<5%). With a competitive format, an immunochromatographic strip was developed using AFB1–bovine serum albumin as the immobilized antigen and anti-AFM1 antibody labeled with gold nanoparticles as tracers. Without any sample preparation, the strip could be directly applied to detect AFM1 contamination in liquid milk. The minimum cut-off concentrations were 0.2 μg L−1 and 1.6 μg kg−1 in liquid milk and powdered milk, respectively, by assessment with the naked eye. Detection of real samples and spiked milk samples indicated the potential of this strip in routine AFM1 monitoring.
Description and Evaluation of a Cigarette Smoke Generation System for Inhalation Studies

ABSTRACT The AMESA Mark III A smoking machine, widely used to generate mainstream cigarette smoke for animal inhalation exposure studies, has been modified to improve operation and reduce maintenance costs. To produce uniform cigarette smoke continuously with a puff frequency ranging from 1 to 3 puffs per minute, the newly designed smoke generator (AMESA Type 1300 Model) was connected to a corresponding number (1 to 3) of peristaltic pumps instead of the piston pump in the AMESA machine. In this way, particle loss from pumping was reduced and the smoke concentration was increased by 10-20%, compared to the AMESA Mark III system. A new ejection system that uses compressed air to blow out the smoked butts was adapted for the generator by AMESA Technologies. This feature reduced the problems previously associated with loading and ejecting of cigarettes and, as a result, reduced cigarette wastage. To further evaluate the AMESA Type 1300 machine, we characterized cigarette smoke generated by using different pu.
Microbial Transformation of a Dihydroxybiphenyl

The X-ray crystal structure of (3S,4R)-3,4-dihydroxy-5-(3-hydroxyphenyl)-5-cyclohexen-1-one, C 12 H 12 O 4 , was determined and showed that the molecule consists of a conjugated cyclohexenone ring substituted by two hydroxyl groups and a 3-hydroxyphenyl group. There are three O-H.O intermolecular hydrogen bonds
First Nitroxide-Mediated Controlled Free-Radical Polymerization of Acrylic Acid

Controlled poly(acrylic acid) homopolymers were synthesized for the first time by direct nitroxide-mediated polymerization of acrylic acid. The polymerizations were performed in 1,4-dioxane solution at 120 °C, using an alkoxyamine initiator based on the N-tert-butyl-N-(1-diethyl phosphono-2,2-dimethyl propyl) nitroxide, SG1. The kinetics were controlled by the addition of free nitroxide at the beginning of the polymerization and the optimal amount was 9 mol % with respect to the initiator. In this case, whatever the initiator concentration, all polymerizations exhibited the same rate and conversion reached 85−90% within 5 h. Although the rate constant of propagation of acrylic acid is very large, its reactivity is moderated by a low activation−deactivation equilibrium constant between active macroradicals and SG1-capped dormant chains. Various alkoxyamine concentrations were investigated to target different molar masses. At high initiator concentrations, the number-average molar mass, Mn, increased linear.