Miracle-dz/UniFAR-FTUs huggingface dataset:
Conservation of Bond Order during Radical Substitution Reactions: Implications for the BEBO Model

The bond energy−bond order model has been used extensively to predict behaviors and energetics of species where ab initio calculations are still too expensive. However, the accuracy of bond order conservation, even for small polyatomic systems, is still unknown. In this paper, we use ab initio calculations at the PMP2 = (full)/6-31 g* and G-2 level to examine bond order conservation for the following gas-phase radical substitution reactions: H* + CH3OH → CH3H* + OH, H* + CH3OH → HOH* + CH3, H* + CH3OH → HH* + CH2OH, H* + CH3OH → HH* + CH3O, H* + CH3OH → H + CH2H*OH, H* + CH3OH → H + CH3OH*. We find that total bond order is approximately conserved during atom transfer reactions, but is not conserved during the more complicated hydrogenolysis reactions or during hydrogen exchange on oxygen. An early transition state is predicted for hydrogen exchange on oxygen, and late ones for the hydrogenolysis reactions. Even though the transition state structures may differ greatly from the ab initio predictions, the .
Structural Metrics Predict Site-Specific Evolutionary Rate in Membrane Bound Proteins

Membrane proteins are involved in many critical biological processes and mutations are linked to various diseases. We examined how the properties of the location of an amino acid residue within the protein structure dictates the rate at which it evolves. We tested 3 structural metrics: WCNSC, WCNCA and RSA for their effectiveness at predicting evolutionary rates within membrane proteins. WCNSC performed better than WCNCA in almost all cases and better than RSA in the majority. However, for some classes of proteins, especially those where the pore is a major feature, the effectiveness of WCN greatly diminished while that of RSA decreased by a lesser degree.
Fabrication of a poly-electrolyte membrane based on cross-linked PTFE thin film by EB irradiation grafting

Polymer electrolyte fuel cell (PEFC) membranes based on cross-linked polytetrafluoroethylene (RX-PTFE) very thin film have been fabricated by radiation grafting with reactive styrene monomers using electron beam irradiation under nitrogen atmosphere at room temperature. The characteristic properties of obtained materials have been measured by differential scanning calorimetry, thermogravimetric analysis, FT-IR spectroscopy, etc. The glass transition temperatures and thermal decomposition temperatures of grafted materials strongly depend on the yields of styrene grafting onto base materials. The higher yields of grafting give lower thermal stability. The ion-exchange capacity of sulfonated materials is 3.0 mEquiv/g. The other properties of obtained membranes, such as chemical structure and rates of hydrogen gas transmission, are discussed.
Extraction of Lignin from Pulping Black Liquor by Organic Acid

The lignin was extracted and purified by organic acid from pulping black liquor, and the process and influencing factors of extraction and purification were studied. The results of single factor experiments showed that the citric acid which contains three -COOH was suitable to extract and purify lignin. The results of orthogonal experiment demonstrated that the optimal condition of extraction and purification was as follows: citric acid saturated solution, 80°C, pH value of acid evolution endpoint was 3.0. The analysis of FT-IR spectrum, GPC and DSC indicated that the type of lignin extracted by citric acid was G-S, and the lignin was characterized as complete structure, higher molecular weight and Tg. The study on extraction technology of high purity lignin by citric acid method is hopeful to overcome the disadvantages of exorbitant cost and secondary pollution caused by the residues from lignin separation. It could change waste into valuables and put resource utilization of pulping black liquor into practice.
A Study on Biodiesel NOx Emission Control With the Reduced Chemical Kinetics Model

In this paper, the effects of the start of injection (SOI) timing and EGR rate on the nitrogen oxide (NOx) emissions of biodiesel-powered diesel engine are studied with computational fluid dynamics (CFD) coupling with a chemical kinetics model. A surrogate biodiesel mechanism consisting of two fuel components is employed as the combustion model of soybean biodiesel. The in-cylinder combustion processes of the cases with four injection timings and three exhaust gas recirculation (EGR) rates are simulated. The simulation results show that the NOx emissions of biodiesel combustion can be effectively improved by SOI retardation or increasing EGR rate. The calculated NOx emissions of the cases with default EGR rate are reduced by 20.3% and 32.9% when the injection timings are delayed by 2-degree and 4-degree crank angle, respectively. The calculated NOx emissions of the cases with 24.0% and 28.0% EGR are reduced by 38.4% and 62.8%, respectively, compared to that of the case with default SOI and 19.2% EGR. But higher EGR rate deteriorates the soot emission. When EGR rate is 28.0% and SOI is advanced by 2-degree, the NOx emission is reduced by 55.1% and soot emission is controlled as that of the case with 24% EGR and default SOI.Copyright © 2013 by ASME
Small-angle electron scattering in the transmission electron microscope

Two methods for performing small-angle electron scattering (SAES) experiments in transmission electron microscopes are described: the long-camera-length method and the selected-area-diffraction method. It is shown experimentally that angular resolutions of a few microradians and a few tenths of milliradians, respectively, are easily obtained by these two methods. A number of examples of the application of SAES to problems in materials science are presented. The use of new high-brightness electron sources is expected to produce significant increases in angular resolution, and the use of electron-energy analyzers will permit the separation of most of the inelastic contribution to the SAES intensity distribution.
SYNTHESIS AND PROPERTIES OF 14-SUBSTITUTED 1,4- THIAZINODIQUINOLINES

Abstract 4,4′-Dichloro-3,3′-diquinolinyl sulfide 1 reacted with aryl-, heteroaryl- and alkylamines in MEDG or phenol to 14-substituted thiazino[2,3-c;6,5-c′]diquinolines 2, Reaction with ammonia, ammonium carbonate or benzylamine led to unsubstituted thiazine 2a, Alkylation of thiazine 2a with alkyl halides gave 14-alkyl-I,4- thiazinodiquinolines 2b, 2c and 2f, The nature of the 14-substituent has a significant effect on 1H NMR and MS spectral properties.
d π –pπ Interaction in trimethylsilyl substituted naphthalenes. Part I. A study using polarography, and charge transfer and ultraviolet spectroscopy

We have carried out experiments to determine the extent of dπ–pπ interaction in silylnaphthalenes by examining a series of SiMe3 and CMe3 substituted naphthalenes using the techniques of polarography, and charge transfer and u.v. spectroscopy. The results show (a) that an inductive effect is operating for the t-butylnaphthalenes, which raises the energies of the lowest unoccupied and of the two highest occupied levels relative to naphthalene and (b) that two opposing effects are operating for the trimethylsilylnaphthalenes, an inductive effect which tends to raise the energy levels, and an electron back donation effect from the aromatic π system to the vacant silicon 3d atomic orbitals which tends to lower the energy levels. This latter effect is the more important for the lowest unoccupied level and the former for the two highest occupied levels.
Pressure Transient Analysis in an Elongated Linear Flow System

The prominent examples of linear flow behavior in the well test literature relate to linear flow within or to a fracture penetrated by a producing well. The resulting pressure transients generally are exhibited in the early portion of a well test and are followed by infinite-acting radial flow behavior and/or boundary effects. In this paper, the linear flow occurs in the formation, which has a predominantly linear shape. Analysis of interference, drawdown, and build up tests is described in theory and illustrated by practical examples. The necessary equations for the analysis are provided for testing gas, geothermal steam, and oil wells. In elongated linear flow systems, the pressure transient behavior associated with linear flow occurs late in the drawdown or build up test. The type curves provided in this work show that this pressure behavior is readily distinguishable from conventional well tests, particularly in interference tests.
InP/InGaAs Heterostructure Bipolar Transistors Grown at Low Temperature by Metalorganic Chemical Vapor Deposition

We describe the performance of InP/InGaAs heterostructure bipolar transistors (HBTs) grown at low temperature by metalorganic chemical vapor deposition (MOCVD). HBTs with a base thickness of 70 nm and doping level of 1×1019 cm-3 show excellent current gain characteristics (current gains hFE>300, ideality factors nB<1.25) at growth temperatures ranging from 500 to 575°C. In addition, Zn out-diffusion from the base layers into the undoped spacer layers is well suppressed to as low as 5×1017 cm-3.
Induced Resistance for Controlling Tomato Fruit Rots by using Safe Chemicals

ifferent pre-harvest treatments of tomato fruits, i.e. Ethiphon, Bion, potasium phosphate monobasic, potasium phosphate dibasic and indole butyric acid (IBA), were evaluated for their capability to control tomato fruit rots under naturally infection and/or artificially inoculation with Alternaria alternata, Botrytis cinerea during storage for 6 weeks throughout the two successive seasons of 2010 and 2011. All pre-harvest treatments protect tomato fruits during cold storage 10C for 6 weeks during the two seasons. Ethiphon treatment at their three concentrations showed the higher efficacy in reducing tomatoes fruits rot which inoculated under artificial infection with B. cinerea, A. alternata and naturally infection followed by Bion treatments. There was positive relationship between increasing the concentration of pre-harvest treatments and their effect on reducing of tomatoes fruits rots during cold storage periods whether under artificial inoculated or under naturally infected during the two seasons 2010 and 2011. All treatments stimulate enzymes activities (chitinase and B-1.3-gluconase). The highest enzymes activities were obtained with Ethiphon followed by Bion compared to other treatments. Data also clearly show that, all treatment performance to enhancing the quality of tomato fruits during cold storage periods by enhancing fruits colour, increase of vitamin C contents and decrease the percentage of losses in tomato fruits fresh weight whether under artificial inoculated or under naturally infection during the two seasons 2010 and 2011.
Synthesis and properties of graphene oxide/graphene nanostructures

We report preparation of graphene oxide (GO)/graphene (G) nanostructures and their structural, optical and electrical properties. GO was synthesized through oxidation of graphite by using the modified Hummer’s method, in which a long oxidation time was combined with a highly effective method for purifying the reaction products. The obtained GO was partially reduced (r-GO) by adding ascorbic acid and thermal annealing. An electrical reduction/oxidation process in r-GO under an electric field was used to form and control the GO/G nanostructures and the potential barrier at the interface. After the treatment, the ratio of the intensity of peak G (1578 cm−1) to that of peak D (1357 cm−1) in Raman spectra of the samples is increased, which is attributed to an increase in the ratio between the sp2 and sp3 regions. The electrical and the luminescence characteristics of the GO/G nanostructures were investigated.
Qualitative and Quantitative HPTLC Methods for Quality Control of Stephania tetrandra

Abstract High performance thin‐layer chromatography (HPTLC) can successfully be employed for quality control of Stephania tetrandra. This paper presents two newly developed methods that are superior to those included in the Chinese Pharmacopoeia. One method, featuring an optimized Soxhlet extraction procedure, is focused on the reproducible separation/detection of tetrandrine, the main alkaloid. Using the same mobile phase [toluene–ethyl acetate–methanol–ammonia 28% (10:10:5:0.3)], this method allows identification of Stephania with high certainty and quantitative evaluation of the tetrandrine content. Quantitation by scanning densitometry is performed at 210 nm. The calibration curve is linear for 50–112.5 ng of tetrandrine per zone. A method for the detection of aristolochic acids (AAs), first published as part of the German Drug Codex, was further improved and adapted for assessing the purity of Stephania raw material. Optimized for sensitivity, this method allows detection of 1 ppm of AA that may be present due to adulteration with toxic species. Complementary to the US food and drug administration's high performance liquid chromatography‐mass spectrometry (HPLC‐MS) method, HPTLC on silica gel with toluene–ethyl acetate–water–formic acid (20:10:1:1) and derivatization with tin(II) chloride is a rapid and very powerful screening tool helping to ensure the safety of Stephania.
Preparation of nano-sized silica/poly(methyl methacrylate) composite latexes by heterocoagulation: comparison of three synthetic routes

Continuing earlier work, 2,2-azobis(isobutyramidine) dihydrochloride (AIBA) was used as a cationic initiator to generate positively charged polymers, and promote interaction of these polymers with the negatively charged surface of colloidal silica particles in aqueous solution. Three different synthetic routes have been investigated. In a first route, emulsion polymerization of MMA, initiated by AIBA, was performed directly in an aqueous suspension of the silica beads using a non-ionic polyoxyethylenic surfactant (NP30). In a second route, AIBA was first adsorbed on the silica surface, and the free amount of initiator was discarded from the suspension. The silica-adsorbed AIBA adduct was suspended in water with the help of surfactant, and used to initiate the emulsion polymerization of MMA. In a third route, cationic PMMA particles were synthesized separately and subsequently adsorbed on the silica surface. Whatever the approach used for their elaboration, the colloidal nanocomposites were shown to exhibit a raspberry-like morphology. Quantitative determination of the amount of surface polymer enabled us to evaluate the efficiency of the heterocoagulation process and establish a comparison among the three synthetic routes.  2004 Society of Chemical Industry
Quantitative analyses of tartaric acid based on terahertz time domain spectroscopy

Terahertz wave is the electromagnetic spectrum situated between microwave and infrared wave. Quantitative analysis based on terahertz spectroscopy is very important for the application of terahertz techniques. But how to realize it is still under study. L-tartaric acid is widely used as acidulant in beverage, and other food, such as soft drinks, wine, candy, bread and some colloidal sweetmeats. In this paper, terahertz time-domain spectroscopy is applied to quantify the tartaric acid. Two methods are employed to process the terahertz spectra of different samples with different content of tartaric acid. The first one is linear regression combining correlation analysis. The second is partial least square (PLS), in which the absorption spectra in the 0.8-1.4THz region are used to quantify the tartaric acid. To compare the performance of these two principles, the relative error of the two methods is analyzed. For this experiment, the first method does better than the second one. But the first method is suitable for the quantitative analysis of materials which has obvious terahertz absorption peaks, while for material which has no obvious terahertz absorption peaks, the second one is more appropriate.
Determination of the Syringyl/Guaiacyl Ratio of Eucalyptus Globulus Wood Lignin by near Infrared-Based Partial Least Squares Regression Models Using Analytical Pyrolysis as the Reference Method

High syringly/guaiacyl (S/G) ratios are advantageous for chemical pulp production due to higher delignification rates, higher pulp yields and lower chemical consumption. Near infrared-based partial least-squares regression (PLS-R) models were developed to assess the S/G ratio of Eucalyptus globulus wood using analytical pyrolysis as the reference method. The PLS-R models obtained using the wavenumber range from 6100cm−1 to 5450cm−1 (1639–1835nm) of the preprocessed spectra using first derivative (1stDer) and first derivative in combination with; vector normalisation (1stDerVN), multiplicative scatter correction (1stDerMSC) and straight-line-subtraction (1stDerSLS), and the second derivative (2ndDer), are well qualified for rapid screening the S/G ratio of Eucalyptus globulus wood. Overall, models using 1stDerVN and 1stDerMSC preprocess (78 samples) requiring only three PLS components have the best statistics with coefficient of determination (r2) = 0.97, root mean square error of cross-validation (RMSECV)=0.025 and residual prediction deviation (RPD) = 5.7
Effect of convective transport on droplet spinodal decomposition in fluids

The effect of convective transport on the late stage growth of droplets in the presence of sedimentation and shear flow is analyzed. The high Peclet number limit (UR/D)$\gg$1 is considered, where U is the characteristic velocity, R is the radius of the droplet, and D is the diffusion coefficient. The growth of the droplet depends on the boundary condition for the fluid velocity at the droplet interface, and two types of boundary conditions are considered. For a rigid interface, which corresponds to the interface between a solid and a fluid, the tangential velocity is zero and the normal velocity is equal to the velocity of the surface. For a mobile interface, which corresponds to an interface between two fluids, the tangential and normal velocities are continuous. These results indicate that the scaling relations for the critical radius are $R_c(t)\alpha t^{(1/2)}$ for a sedimenting droplet with a rigid interface, $R_c(t)\alpha t^{(2/3)}$ for a sedimenting droplet with a mobile interface, $R_c(t)\alpha t^{(3/7)}$ for a droplet with a rigid interface in a simple shear flow, and $R_c(t)\alpha t^{(1/2)}$ for a droplet with a mobile interface in a simple shear flow. The rate of droplet growth is enhanced by a factor of $P_e^{(1/3)}$ for rigid interfaces and $P_e^{(1/2)}$ for mobile interfaces.
General method for simulation of 2D GISAXS intensities for any nanostructured film using discrete Fourier transforms

A fast, flexible 2D GISAXS simulation method based on the distorted-wave Born approximation (DWBA) has been developed for nanostructured thin films using discrete Fourier transforms of a N × N × N matrix that represents the electron density. By expressing the electron density in matrix form, various models of electron density distributions can be easily simulated and compared to experimental data. In addition to modeling the effects of overall symmetry and orientation on the relative intensities of the Bragg peaks, this approach can be used to evaluate specific details of the nanostructure such as pore connectivity, domain size, domain shape, positional disorder, orientation disorder, and polydispersity. These effects are included in a natural way without making a decoupling approximation between structure factor and form factor. The range of reciprocal space simulated is set by the size of the matrix N and the scale factor β that sets the real-space length of each matrix element, given by 1/(2Nβ) < |s| <.
Predicting Critical Micelle Concentration Values of Non-Ionic Surfactants by Using Artificial Neural Networks

Abstract Critical Micelle Concentration is a fundamental property on studying behaviour of surfactants. In general terms it depends on temperature, pressure and on the existence and concentration of other surface-active substances and electrolytes. In this work it is presented a model based on Artificial Neural Networks to obtain predictive values of Critical Micelle Concentration (CMC) of some non-ionic surfactants. ANN model works using topological descriptors of the molecules involved together with already known CMC values and provides predictive values for new cases. It is proposed a specific architecture for ANN consisting of an input layer with seven neurons, one intermediate layer with fourteen neurons and one neuron in the output layer. This ANN model seems to be a good method for forecast CMC.
Molecular mechanism of alkane oxidation involving binuclear iron complexes

The use of substrate probes for establishing the nature of intermediates and the mechanism of alkane oxidation by peroxides upon catalysis by binuclear iron complexes {[Fe 2 OL 2 (H 2 O) 2 ](ClO 4 ) 4 , where L = bpy, 4,4′-Me 2 bpy or 5-NO 2 phen (bpy = bipyridine, phen = phenanthroline)}, the analysis of the dependence of test parameters on the nature of a substituent in a ligand and the effect of dioxygen all make it possible to diagnose a two-electron mechanism for the transfer of the oxygen atom from peroxide to the C H bond of an alkane via metal complexes.
Thermodynamic vs kinetic aspects in the formation and morphological transitions of crew-cut aggregates produced by self-assembly of polystyrene-b-poly(acrylic acid) block copolymers in dilute solution

Thermodynamic vs kinetic aspects of the formation of crew-cut aggregates of various structures prepared from polystyrene-b-poly(acrylic acid) diblock copolymers in DMF/water mixtures are explored. In particular, the reversibility of the transitions between the crew-cut aggregates of various morphologies is studied by “jumps” in the polymer or ion concentration at various water contents. The aggregates are prepared by two different methods: micellization is induced either by the addition of water to polymer/DMF solutions or by the direct dissolution of the polymer in DMF/water mixtures. It is shown that as the polymer concentration increases, the morphology of the aggregates changes from spheres to rodlike micelles, to interconnected rods, and then to bilayers. As the water content increases, the boundaries for the formation of the different morphologies move toward lower polymer concentrations. The thermodynamic vs kinetic control of the morphology depends largely on the water content and the method of a.
Effect of Land-Use History on Soil Carbon and Nitrogen in a Mediterranean Catchment

The impact of land use on soil organic matter was investigated. Five land cover types (pine forest, olive groves, wheat, wheat/maize cultivation systems, and a shrub pasture) belonging to three land-use categories from the same catchment in the island of Lesvos, Greece, were used. The soils developed under similar pedogenetic processes and accepted similar agricultural practices for at least 30 years. The results showed that the land-use and cover types ranged according to their total soil carbon (C) content as follows: forest > double cultivation > wheat > olive > pasture. Crop plantations contained 31 to 40% less C at their upper 0- to 45-cm layer than forest. Pasture had shallow soils with a small C accumulation but high C concentration, whereas olive groves had the lowest concentrations of both soil C and nitrogen (N). Olive grove soils were the most prone to degradation but possessed the greatest potential for C sequestration.
Laser frequency stabilization to excited state transitions using electromagnetically induced transparency in a cascade system

We demonstrate laser frequency stabilization to excited state transitions using cascade electromagnetically induced transparency. Using a room temperature Rb vapor cell as a reference, we stabilize a first diode laser to the D2 transition and a second laser to a transition from the intermediate 5P3/2 state to a highly excited state with principal quantum number n=19–70. A combined laser linewidth of 280±50 kHz over a 100 μs time period is achieved. This method may be applied generally to any cascade system and allows laser stabilization to an atomic reference in the absence of a direct absorption signal.