Miracle-dz/UniFAR-FTUs huggingface dataset:
6H-Pyrrolo[3,2-b:4,5-b′]bis[1,4]benzothiazines: facilely synthesized semiconductors for organic field-effect transistors

6H-Pyrrolo[3,2-b:4,5-b′]bis[1,4]benzothiazine (PBBTZ, 1) and its two 6-substituted derivatives (2 and 3) were conveniently synthesized. Their optical properties were studied by UV-vis and fluorescence spectroscopy, and electrochemical properties were investigated by cyclic voltammetry (CV). Good thermal stability was observed by thermogravimetric analysis. X-Ray analysis revealed a coplanar structure and a column stacking in the single crystal of compound 1. OFET measurements showed that 1–3 were p-type semiconductors. The performance of these devices displayed good reproducibility at ambient conditions. When devices containing 1 were fabricated on OTS-treated SiO2/Si substrates at 60 °C, the best performance was achieved with the average hole mobility as high as 0.34 cm2V−1 s−1 and the on/off ratio about 106–107. This performance resulted from the well-ordered molecular packing as revealed by XRD and AFM analysis.
In situ infrared measurements of film and gas properties during the plasma deposition of amorphous hydrogenated silicon

This research has performed preliminary in situ Fourier transform infrared (FTIR) measurements during the plasma deposition of amorphous silicon (a‐Si:H). Experiments demonstrate both gas phase and film measurements within a simple SiH4 plasma reactor using a specially modified FTIR spectrometer. Films are deposited on substrates of either gold (mirror finish) or stainless steel (matte finish). In particular, in situ emission/reflection FTIR of the film yields information about surface temperature, film thickness, and film composition. We have measured surface temperature to ±5 K and detected the onset of poor film growth at a thickness of 500–1000 A using the 2080 cm−1 absorption feature. A simple model for the reflectance of a film on a metal is employed to determine the thickness of the films. In situ emission/transmission FTIR of the plasma determines the gas composition and average gas temperature. Measurements show that the silane conversion is ∼11% within the plasma region for a typical deposition .
Modification of data processing and interpretation of results related to the use of multiparameter correlation analysis: introduction of additional characteristics and criteria. Part 1: Application to the treatment of solvent effects

Several problems with multilinear regression analysis in chemistry are discussed. These problems are connected with the establishment of scales and their inclusion in the model of significant and, as usually desired, physically or chemically meaningful descriptors. The detection of abundant and interrelated descriptors and of the presence and the mode of elimination of strongly deviating data are discussed, as well as the estimation of absent values for incomplete (considering a set of rows treated) descriptor scales. They were studied using an incomplete data matrix for 359 solvent-dependent processes and solvent parameter scales for 45 solvents. Some non-traditional problems, related to the formalism of application of the basic principles of correlation analysis, are discussed and corresponding characteristics and criteria specified. A quantitative measure of the orthogonality of correlation matrices was introduced. As a result of the realization of this approach, it was found that for multiparameter correlation analyses of the solvent-dependent processes under consideration, seven residual (i.e. free from mutual contributions) descriptors are significant and sufficient. Copyright © 2004 John Wiley & Sons, Ltd.
Correlation between composition and structure in boracites

In a combined x-ray diffraction and density functional theory based study the bonding properties of several halogenide boracites have been investigated. We show that DFT calculations reliably reproduce the small spontaneous deformations of non-cubic boracites and that they therefore can be used to predict pressure-induced structural changes. Specifically, we predict the compressibility and the pressure-induced deformation of Mg–Cl boracite. Earlier findings concerning an unusual bond length in Co–Cl boracite are challenged. The arrangement of the halogenide ions and metal cations along chains running through the structure is rationalized in terms of electronegativity differences. We also show that the substitution of the halogenide or metal ions has no significant effect on the B–O bonds.
High-throughput quantum chemistry and virtual screening for OLED material components

Computational structure enumeration, analysis using an automated simulation workflow and filtering of large chemical structure libraries to identify lead systems, has become a central paradigm in drug discovery research. Transferring this paradigm to challenges in materials science is now possible due to advances in the speed of computational resources and the efficiency and stability of chemical simulation packages. State-of-the-art software tools that have been developed for drug discovery can be applied to efficiently explore the chemical design space to identify solutions for problems such as organic light-emitting diode material components. In this work, virtual screening for OLED materials based on intrinsic quantum mechanical properties is illustrated. Also, a new approach to more reliably identify candidate systems is introduced that is based on the chemical reaction energetics of defect pathways for OLED materials.
Detailed kinetic modeling of autocatalysis in methane pyrolysis

A detailed kinetic model is developed to explain the observed acceleration in rates of product formation during the pyrolysis of methane at 0.58 atm and 1038 K. This model, obtained by a systematic simplification of a much larger one, consists of 44 reactions involving 25 species. The model includes a number of reactions involving chemically activated complexes formed by radical addition and recombination reactions, with rates for unimolecular reaction and bimolecular stabilization of these energized complexes evaluated with a QRRK formalism. A combination of reaction rate analysis as well as sensitivity analysis is used to show that these chemically activated reactions lead to surprisingly rapid production of cyclopentadiene at very low extents of conversion ({approx} 0.1%) and that dissociation of cyclopentadiene accounts for the acceleration in rate. An optimization procedure was used to obtain an accurate description of the observed kinetics without compromising the theoretical plausibility of the rate constants.
Synthetic Amorphous Silicon Dioxide (NM-200, NM-201, NM-202, NM-203, NM-204): Characterisation and Physico-Chemical Properties

The European Commission's Joint Research Centre (JRC) provides scientific support to European Union policy including nanotechnology. Within this context, the JRC launched, in February 2011, a repository for Representative Test Materials (RTMs), based on preparatory work started in 2008. It supports both EU and international research projects, and especially the OECD Working Party on Manufactured Nanomaterials (WPMN). The WPMN leads an exploratory testing programme "Testing a Representative set of Manufactured Nanomaterials" for the development and collection of data on characterisation, toxicological and ecotoxicological properties, as well as risk assessment and safety evaluation of nanomaterials. The purpose is to understand the applicability of the OECD Test Guidelines for the testing of nanomaterials as well as end-points relevant for such materials. The Repository responds to a need for nanosafety research purposes: availability of nanomaterial from a single production batch to enhance the comparability of results between different research laboratories and projects. The availability of representative nanomaterials to the international scientific community furthermore enhances and enables development of safe materials and products. The present report presents the physico-chemical characterisation of the synthetic amorphous silicon dioxide (SiO2, SAS) from the JRC repository: NM-200, NM-201, NM-202, NM-203 and NM-204. NM-200 was selected as principal material for the OECD test programme "Testing a representative set of manufactured nanomaterials". NM-200, NM-201 and NM-204 (precipitated SAS) are produced via the precipitation process, whereas NM-202 and NM-203 (fumed or pyrogenic SAS) are produced via a high temperature process. Each of these NMs originates from one respective batch of commercially manufactured SAS. They are nanostructured, i.e. they consist of aggregated primary particles. The SAS NMs may be used as a representative material in the measurement and testing with regard to hazard identification, risk and exposure assessment studies. The results for more than 15 endpoints are addressed in the present report, including physical-chemical properties, such as size and size distribution, crystallite size and electron microscopy images. Sample and test item preparation procedures are addressed. The results are based on studies by several European laboratories participating to the NANOGENOTOX Joint Action, as well as the JRC. Table of contents
N-15-H-1 bond length determination in natural abundance by inverse detection in fast-MAS solid-state NMR spectroscopy

A solid-state 15N−1H correlation NMR experiment is presented, which provides a substantial gain in signal sensitivity by 1H inverse detection under fast MAS conditions and allows for the precise determination of NH bond lengths via heteronuclear 1H−15N dipole−dipole couplings on samples naturally abundant in 15N. Pulsed-field gradients or, alternatively, radio frequency pulses ensure suppression of unwanted 1H signals. In this way, natural-abundance 15N−1H correlation NMR spectroscopy becomes feasible in the solid state with experiment times of a few hours. The dipole−dipole coupling constants are extracted from spinning sideband patterns generated by recently developed recoupling strategies. The information on 15N/1H chemical shifts and quantitative 15N−1H couplings can readily be combined in a single two-dimensional spectrum using a split-t1 approach.
Synthesis, characterization, equilibria and biological activity of dimethyltin(IV) complex with 1,4-piperazine

The interaction of dimethyltin(IV) dichloride (DMT) with 1,4-piperazine (PIP) was investigated. The complex formation equilibria of the complexes formed in solution were investigated. The stoichiometry and stability constants of the complexes formed in solution phase were determined at different temperatures and in solutions of dioxane–water mixtures of different dielectric constants. The equilibrium constant for the displacement of piperazine coordinated to dimethyltin(IV) by inosine as a representative of DNA was calculated. (DMT)(PIP)·3H2O was synthesized and characterized by elemental analysis, spectral, and thermal techniques. The antitumor activity of the complex was screened.
Standardized polymerizations of ethylene and propene with bridged and unbridged metallocene derivatives: A comparison†

Ethylene and propene were homopolymerized with 11 different metallocene-methylalumin-oxane (MAO) catalysts 1–11 using a constant set of parameters. The catalytic activity of the two unbridged and 9 ansa-metallocenes as well as the properties of the polymers, such as molecular weight, width of molecular weight distribution, melting point, and, with polypropene, chain microstructure, were investigated. It was found that structure variations of the catalysts cause rather different catalytic behaviour, which further diversifies the performances with the two different monomers. In some cases this comparison allows insight into the nature of the influencing factors.
Development of a sparging technique for volatile emissions from potato (Solanum tuberosum)

Accumulation of volatile emissions from plants grown in tightly closed growth chambers may have allelopathic or phytotoxic properties. Whole air analysis of a closed chamber includes both biotic and abiotic volatile emissions. A method for characterization and quantification of biogenic emissions solely from plantlets was developed to investigate this complex mixture of volatile organic compounds. Volatile organic compounds from potato (Solanum tuberosum L. cv. Norland) were isolated, separated and identified using an in-line configuration consisting of a purge and trap concentrator with sparging vessels coupled to a GC/MS system. Analyses identified plant volatile compounds: transcaryophyllene, alpha-humulene, thiobismethane, hexanal, cis-3-hexen-1-ol, and cis-3-hexenyl acetate.
The Free Volume Theory of Multicomponent Fluid Mixtures

The free volume theory of the liquid state is extended to multicomponent mixtures by using the method of moments in the treatment of the order‐disorder problem. Retention of only the first moment yields an approximation to the partition function which has recently been studied by Prigogine and Garikian and by Prigogine and Mathot. An approximation equivalent to retaining the third moment is given, and the calculation of the thermodynamic functions from the first moment approximation is discussed.
Chemical composition and antimicrobial activity of essential oils from Tunisian Pituranthos tortuosus (Coss.) Maire

The aerial parts of Pituranthos tortuosus, collected during November and April, were analysed by GC and GC-MS. In total, 56 compounds were identified by their retention indices. Antimicrobial assays showed that the November essential oil is more effective than that of April against the Gram-positive bacteria Enterococcus faecalis and Staphylococcus aureus. The April essential oil displayed the highest activity against Staphylococcus aureus.
Electrical Resistivity and Phase Transformation in Steels

Changes in electrical resistance accompanying transformations in steels with magnetic change (e.g. γ → martensite/bainite) and without magnetic change (e.g. γ → α, above Curie temperature) have been examined; the former class affects the resistivity the latter does not. Next, while the efficacy of electrical resistivity measurement in capturing the well‐known features of austenite stabilization (e.g. over – ageing, reversibility, and influence of prior martensite amount and so on) in high carbon steels has been reported in an earlier publication, new features (e.g. increase in resistance ‐increase at very low temperatures, change in temperature co‐efficient of resistivity in the stabilized material etc.) are highlighted here. Finally, the work shows that a quantitative estimate of precipitation in the copper bearing, age‐hardenable HSLA‐100 steel during tempering can be done by continuous electrical resistivity measurement. These data also allow an in‐depth kinetic analysis using the Johnson‐Mehl‐Avrami equation.
Electron-Ion Coupling in Shocked Energetic Materials

The magnitude and role of electronic excitations in shocked energetic materials are studied theoretically using quantum molecular dynamics simulations. Focusing on the detonating primary explosive HN3 (hydrazoic acid), this work finds that the material transiently exhibits a high level of electronic excitation characterized by carrier densities in excess of 1021 cm–3, or one electronic excitation for every eight molecules. Electronic excitations enhance the kinetics of chemical decomposition by ∼30%. The electronic heat capacity has a minor impact on the temperatures exhibited, on the order of 100 K. These simulations are performed using the self-consistent charge density functional tight-binding method (SCC-DFTB) combined with a new modification of a multiscale computational scheme for simulation of the coupling between electrons and ions in shocked matter.
Transparent poly(vinyl alcohol) hydrogel with high water content and high strength

To develop a transparent poly(vinyl alcohol) (PVA) hydrogel with high water content and high strength, we studied the physical gelation of PVA solutions and found that low temperature crystallization of PVA solutions in mixed solvents consisting of water and a water-miscible organic solvent yields transparent gels. The strength and transparency of the PVA hydrogel is dependent on both the type of organic solvent and the mixing ratio of water/organic solvent. A mixed solvent from water/dimethyl sulfoxide resulted in the highest transparency and the highest tensile strength among the water/organic solvent combination studied. A plausible mechanism is proposed for the formation of transparent and strong hydrogels on the basis of the results obtained.
J‐ICE: a new Jmol interface for handling and visualizing crystallographic and electronic properties

The growth in complexity of quantum mechanical software packages for modelling the physicochemical properties of crystalline materials may hinder their usability by the vast majority of non-specialized users. Consequently, a free operating-system-independent graphical user interface (GUI) has been developed to drive the most common simulation packages for treating both molecules and solids. In order to maintain maximum portability and graphical efficiency, the popular molecular graphics engine Jmol, written in the portable Java language, has been combined with a specialized GUI encoded in HTML and JavaScript. This framework, called J-ICE, allows users to visualize, build and manipulate complex input or output results (derived from modelling) entirely via a web server, i.e. without the burden of installing complex packages. This solution also dramatically speeds up both the development procedure and bug fixing. Among the range of software appropriate for modelling condensed matter, the focus of J-ICE is currently only on CRYSTAL09 and VASP.
Voltage-dependent coupling of light into ITO-covered waveguides

Indium tin oxide (ITO)-covered waveguides incorporating a grating and immersed in a fluid have been used to study the incoupling of light as a function of a voltage applied between the ITO and an electrode parallel to the waveguide and also immersed in the fluid. The optical set-up is typical for adsorption and binding studies of (bio)chemical material, but the voltage dependence is a new feature. Applied voltages, positive at the ITO surface, shifted the incoupling angle of linearly polarized laser light. Voltages below 1 V are sufficient; above, the effect saturates. dc and ac protocols have been applied. Weak dependence on solution composition and strong asymmetry with respect to the polarity of the applied potential imply that the ITO itself is involved in the effect. It is proposed to use it as a reference or compensation method for standard biosensor applications. It could considerably simplify them, avoiding high-precision goniometers or high-resolution position-sensitive devices for determining waveguide-effective refractive index shifts, and using a simple voltage sweep instead.
Crystal Structure of α,α‐Trehalose–Calcium Chloride Monohydrate Complex

The crystal structure of α,α‐trehalose hydrate complexed with calcium chloride was determined by X‐ray crystallography and its structural comparison with the α,α‐trehalose–CaBr2 · H2O complex was performed. The crystal system of the α,α‐trehalose–CaCl2 · H2O complex, C12H22O11 · CaCl2 · H2O, is orthorhombic and C2221 space group with a=10.8984(8), b=11.4260(6), and c=15.059(1)Å. Although its coordination closely resembled that of the α,α‐trehalose–CaBr2 · H2O complex published formerly assuming a pentagonal bipyramidal arrangement, a difference between two α,α‐trehalose–halide complexes was observed along the c‐axis in the infinite channels occupied by water molecules.
The electroluminescence and scanning tunneling microscopy of single molecules

The scanning tunneling microscopy (STM) of single molecules has become a prominent experimental method in the field of molecular electronics. It has been found that in STM experiments, when an electric current flows through a single molecule, the molecule may luminesce. This electroluminescence, in conjunction with traditional STM data, provides a potentially important additional degree of freedom for understanding nanoscale systems. This thesis describes exploratory theoretical work on the newly emerging phenomenon of molecular electroluminescence, and its relationship to the scanning tunneling microscopy of single molecules. A local electrode framework is progressively developed, in order to explain single-molecule electroluminescence data as well as simulating STM currentvoltage characteristics and topographic maps for molecules on complex substrates. The molecule Zn(II)-etioporphyrin I is chosen for detailed analysis and comparison with experiment. Electron transport is studied using Landauer theory that relates electric current to the transmission probability for an electron to scatter through the molecule. The theoretical approach utilizes tight binding and extended Huckel approaches for the electrodes and molecule, a charge-conserving scheme to self-consistently model the influence of electric fields and electric currents on the molecular energy level structure, and Fermi’s golden rule in calculating electroluminescence. A single coherent framework is ultimately achieved that explains for the first time both the electric current data and molecular electroluminescence in a molecular system and elucidates the physics underlying a rich and previously puzzling array of interlinked optical and transport phenomena.
A photochemical investigation of two suncreen absorbers in a polar and a non-polar medium.

Protection against the harmful effects of ultraviolet radiation is of increasing importance due to the depletion of stratospheric ozone, which shields the earth from har~nful UVC rays (in the range 200-280 nm) and some UVB rays (in the range 280290 nm). In addition, as the skin is repeatedly exposed to solar radiation, the possibility exists that the incidence of skin cancer is enhanced. This has led to the increased use of commercial sunscreens, which apart from their benefits, also have undesirable effects such as photodegradation and skin penetration. We therefore studied the photodegradation of two sunscreen absorbers that are used in most sunscreen formulations. The combination of the UVB filter, 2-ethylhexyl-p-methoxycinnamate (EHMC), and the UVA filter, avobenzone (AVO), are commonly used in sunscreen products. These two filters are known to exhibit differing photostabilities in different media. The aim of this project was to investigate their photochemical behaviour in a polar and a nonpolar solvent and to identify the UV-induced breakdown products. Methanol was chosen as the polar medium and cyclohexane as the non-polar medium. The sunscreen filters were irradiated either singly or in combination in the two solvents with wavelengths greater than 300 nm. The irradiated samples were analysed by UVspectrophotometry, high performance liquid chromatography (HPLC) and gas chromatography (GC). The effects of direct irradiation with UVB and UVA light, quenchers and photosensitisers were also examined. EHMC is supplied commercially as the trans-isomer and upon irradiation photoisomerises, in both methanol and cyclohexane, to its eis-isomer. AVO is photostable in methanol but photodegrades in cyclohexane. This behaviour is also evident when mixtures ofthe two filters are irradiated. The loss in absorbance of both EHMC and AVO was monitored by DV-spectrophotometric analysis. Since EHMC does not absorb DV light at the wavelength of maximum absorbance of AVO, a method to quantify the amount of EHMC and AVO present in the mixture was devised.