Miracle-dz/UniFAR-FTUs huggingface dataset:
Reaction of Isocyanate-Functionalised Silicon Wafers with Complex Amino Compounds

A feasible method of grafting complex amine structures (methyl ester of glycine, Rho-Lys-Arg-NH2, amine-terminated oligonucleotide and 7,8,11,12-tetrahydro-5-hexahelicenamine) onto a silicon wafer surface is described. The two step process comprises (1) anchoring 10-isocyanatodecyltrichlorosilane to a 1.8–2-nm thin silica layer on a single silicon wafer crystal (100) and (2) the attachment of amine substrates through a urea linkage by reacting those with isocyanate groups on the wafer surface. Both steps can be monitored by ATR FTIR showing the appearance/disappearance of the isocyanate band. Measuring the contact angles along with the AFM imaging of the surfaces indicated the formation of the monolayers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Transport properties of rigid and flexible macromolecules by brownian dynamics simulation

The method of Ermak and McCammon [Ermak, D. L. & McCammon, J. A. (1978) J. Chem. Phys. 69, 1352–1360] is used to simulate the Brownian dynamics of a system of identical, interacting beads. In the present study, we use the method to obtain transport coefficients for a variety of rigid and flexible structures modeled as arrays of spherical subunits. Constraints are enforced using the SHAKE algorithm or a modification, SHAKE‐HI, that is described for the first time. In SHAKE‐HI, hydrodynamic interactions between subunits are taken into account when the constraints are enforced. Use of SHAKE‐HI yields transport coefficients that are in perfect agreement with those obtained by other methods. The primary advantage of the present method is its generality. We also propose that multistep Brownian dynamics may be important in simulating actual experiments (such as fluorescence depolarization) on well‐defined model systems that possess an arbitrary degree of internal flexibility.
Quantification Method for Triglyceride Molecular Species in Fish Oil with High Performance Liquid Chromatography-Ultraviolet Detector

A new quantification method for triglyceride (TG) molecular species contained in fish oil was developed using high performance liquid chromatography (HPLC)-ultraviolet detector (UV) system. In this experiment, triacontyl silane column and a mixture of alcohol and acetonitrile were used for column and mobile phase, respectively. Fifteen kinds of TG molecular species exist in fish oil were collected and the calibration curves monitored at 210nm were acquired for each TG molecular species. Also, evaporative light scattering detector (ELSD), widely used for the detection of fish oil TG molecular species, was tandem jointed after UV to compare the calibration curves for each TG molecular species. As the results, the calibration curves by UV with isocratic elution system were linear lines, on the contrary, those by ELSD were not linear. The slope of each calibration curve by UV was not the same and there was a tendency that TG molecular species having big partition number indicates a small slope calibration curve. The HPLC-UV with gradient system was also examined, but a few of standard TGs did not provide linear calibration curve. Consequently, we concluded that isocratic HPLC-UV system would be an available method for the quantification of TG molecular species in fish oil.
Effects of polymer‐grafted natural nanocrystals on the structure and mechanical properties of poly(lactic acid): A case of cellulose whisker‐graft‐polycaprolactone

In this work, polysaccharide nanocrystals—rodlike cellulose whiskers (CWs)—were surface-grafted with polycaprolactone (PCL) via microwave-assisted ring-opening polymerization, and filaceous cellulose whisker-graft-polycaprolactone (CW-g-PCL) nanoparticles were produced. Moreover, the resultant nanoparticles were incorporated into poly(lactic acid) (PLA) as a matrix, and they showed superior function for enhancing the mechanical performance of PLA-based materials in comparison with platelet-like nanoparticles of starch nanocrystal-graft-PCL. The optimal loading level of CW-g-PCL was 8 wt %, and this resulted in simultaneous enhancements of the strength and elongation of approximately 1.9- and 10.7-fold, respectively, over those of the neat PLA material. In this case, the rigid CW nanoparticles contributed to the endurance of higher stress, whereas the grafted PCL chains improved the association between the PLA matrix and the CW-g-PCL filler and hence facilitated the transfer of stress to the rigid CW nanoparticles. Furthermore, such a fully biodegradable PLA-based nanocomposite shows great potential for environmentally friendly materials because of its high mechanical performance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The interaction of atoms and molecules with solid surfaces II—The evaporation of adsorbed atoms

This paper is an extension of the preceding one to the case of transitions from a state of discrete energy to one in the continuous region. By summing the transition probabilities from the ground state to the states in the continuous region an expression is obtained for the probability of evaporation from a solid surface. We are thus able to evaluate the average length of time spent by an adsorbed atom on a surface. 2- Transition Probabilities In order to calculate the matrix elements corresponding to transitions to states of positive energy, we must first consider the wave functions of the continuous spectrum of the equation (3a) of the preceding paper.
N-Allyl-N-Methyl Piperidinium Bis(Trifluoromethanesulfonyl) Imide as a Co-Solvent in Li-Ion Batteries

Mixtures of an ionic liquid (IL) with organic solvents and a lithium salt have been studied in order to develop new electrolytes for lithium-ion cells with enhanced safety profiles. In this work, N-allyl-N-methylpiperidinium bis (trifluoromethanesulfonyl) imide (PP1ATFSI) was synthesized and characterized to exhibit high decomposition temperature and wide electrochemical stability window. The evaluation of the coin cell LiFePO4/Li with the mixed electrolyte based on PP1ATFSI with 0.35mol/kg LiTFSI, and 30 wt% VC/DMC (1:1) shows a nice reversibility and cycle performances. All above prove that PP1ATFSI is one of the most promising safety electrolytes of Li-ion battery.
Chemically prepared magnetic nanoparticles

Abstract Nanotechnology has spurred efforts to design and produce nanoscale components for incorporation into devices. Magnetic nanoparticles are an important class of functional materials, possessing unique magnetic properties due to their reduced size (below 100 nm) with potential for use in devices with reduced dimensions. Recent advances in processing by chemical synthesis and the characterisation of magnetic nanoparticles are the focus of this review. Emphasis has been placed on the various solution chemistry techniques used to synthesise particles, including: precipitation, borohydride reduction, hydrothermal, reverse micelles, polyol, sol–gel, thermolysis, photolysis, sonolysis, multisynthesis processing and electrochemical techniques. The challenges and methods for examining the structural, morphological, and magnetic properties of these materials are described.
Proposal and simulation of differential double-pulse pair Brillouin optical time-domain analysis

A differential double-pulse pair Brillouin optical time-domain analysis (DDP-BOTDA) combined with the double-pulsed technique and the differential pulse-width pair technique is proposed and simulated to detect small temperature and strain changes. Using a symmetrical double-pulse pair, the system can detect small Brillouin shift with high spatial resolution and large dynamic range. Sub-meter spatial resolution is decided by the difference between the pulse-width and the peak and valley of the spectrum which is derived from differential pump depletion signals, and detectable Brillouin shift is less than 1 MHz.
Stratospheric ozone chemistry

Abstract Stratospheric ozone is important in shielding the planet from harmful solar radiation and tropospheric ozone and, while harmful to plants and humans in large amounts is also, in combination with water vapour, a major source of OH radicals which act as a detergent for many chemical species emitted into the troposphere by natural and anthropogenic emissions. This paper presents the chemistry affecting both tropospheric and stratospheric ozone with an emphasis on the stratosphere. In the decade since the last Environment Canada report on stratospheric ozone (Wardle et al. , 1997) there have been many advances in our understanding. Recent studies have shown that inorganic chlorine, which is the main contributor to polar ozone depletion and middle stratospheric ozone reduction, has started to decrease as a result of the implementation of the Montreal Protocol. During this period, Canada launched a small satellite, SCISAT‐1. We discuss the chemical processes related to polar ozone loss, such as chlorine activation and denitrification, using data from SCISAT‐1. These measurements and those from the Microwave Limb Sounder (MLS) instrument on the Aura satellite confirm that the chlorine deactivation in the Arctic is distinct from that in the Antarctic. Recent studies show that our understanding of the middle atmosphere bromine budget needs improvement. Using measured constraints reproduces the polar and extra‐polar ozone loss better. In addition, recent studies have addressed the variation of middle atmosphere ozone with solar variability. These studies have investigated the variation of solar radiation and related energetic particle precipitation (EPP) such as auroral precipitation, solar proton events (SPEs) as well as cosmic rays. Although there was some appreciation of these effects in the past, current three‐dimensional (3‐D) models suggest that the EPP may have a greater effect on middle atmospheric ozone than was previously realized. Stratospheric ozone loss allows the penetration of more ultraviolet (UV) radiation into the lower atmosphere, and thus may result in an increase in the oxidation state of the troposphere and affect tropospheric chemistry. Quantitative assessment of the effect of lightning on the ozone budget of the upper troposphere and lower stratosphere (UTLS) is a current challenge, while increases in the size of commercial aviation fleets have a positive radiative forcing in this region. To include the feedbacks between radiation, chemistry and dynamics associated with atmospheric change, coupled chemistry‐climate models (CCMs) have been developed during the past decade. While these models still require improvement in transport and physical processes they generally predict that the Antarctic ozone layer will recover to the levels prior to 1980 by the middle of this century as a result of decreasing atmospheric chlorine and a cooling stratosphere. According to a recent semi‐empirical relationship between ozone loss and Arctic meteorological conditions (Rex et al. , 2004), a colder Arctic stratosphere may result in more severe ozone loss in the boreal springtime in the near future.
ROTATION OF STRUCTURAL WATER INSIDE A PROTEIN : CALCULATION OF THE RATE AND VIBRATIONAL ENTROPY OF ACTIVATION

Water molecules buried inside a protein are often considered as an integral part of the structure and are increasingly used as NMR probes to study the dynamics of proteins (Denisov, V.; Peters, J.; Horlein, H. D.; Halle, B. Nat. Struct. Biol. 1996, 3, 505). The present calculations give new insights into the mobility of such structural water. Reaction path calculations using conjugate peak refinement (Fischer, S.; Karplus, M. Chem. Phys. Lett. 1992, 194, 252) are carried out to compute the transition state and activation energy (9.7 kcal mol-1) for the rotation of a water molecule buried in the protein bovine pancreatic trypsin inhibitor. These are compared to the values calculated (10−12.3 kcal mol-1) for the same process in ice, for which the experimental value has been determined (12.8 ± 0.9 kcal mol-1). The process, which results in the interchange of the two water hydrogens, is similar in both systems. It is not a simple C2-flip of the buried water, but a complex motion involving two successive rotat.
PIGS or Lambs revisited: Reassessing the Role of Rating Agencies in the European Sovereign Debt Crisis

This paper examines whether credit rating agencies have indeed played as active a role in the Euro crisis as previously asserted. Using panel data methods for a set of 11 EMU countries, it assesses the robustness of an earlier analysis to the inclusion of additional explanatory variables. Whereas rating agencies were previously shown to have placed a significant markup on GIPS countries during the Euro crisis, this paper finds that its size was overstated as a result of omitted variable bias, although it remains significant. A cross-agency comparison shows that the Big Three rating agencies used this markup to a differential extent, however. A subsequent analysis of the markup’s effect on yield spreads finds only inconclusive evidence to refute the argument that rating agencies played an active role in the crisis. Central to the analysis is the inclusion of institutional variables from the World Governance Indicators. A novel functional form of the indicator Rule of Law is shown to perform well in explaining sovereign ratings, but not in the subsequent analysis of yield spreads.
Progress in plasma spectroscopic diagnostics based on Stark effect in atoms and molecules

The present state of Stark plasma spectroscopy is discussed. The possibilities of measurements of electric field and related plasma parameters are considered. A brief theory of linear and nonlinear Stark effect is outlined. The specific features of Stark effect — shifts, splitting and related line broadening, forbidden transitions — are described for the electric fields of differing nature — correlated external static and alternative fields, plasma turbulence fields, microfields generated by charged particles. Techniques based on classical emission spectroscopy, and novel linear and nonlinear laser techniques are considered. It is shown that the application of recently developed coherent laser spectroscopic methods radically improves the possibilities of electric fields measurements for the high pressure range.
Effective immobilization of lipase onto a porous gelatin‐co‐Poly(vinyl alcohol) copolymer and evaluation of its hydrolytic properties

Crosslinked copolymers of gelatin and poly(vinyl alcohol) (PVA) with excellent water absorption and water retention abilities were successfully synthesized using 60Co γ radiation. Ammonium persulfate (APS), as a water-soluble initiator and sodium bicarbonate (NaHCO3) as a foaming agent were used. The best synthesis conditions were evaluated with regard to the maximum percentage of swelling as a function of the APS concentration, NaHCO3 concentration, amount of water, and reaction time. The maximum swelling percentage (1694.59%) of the copolymer gelatin-co-PVA, was obtained at the optimum parameters [APS] = 2.92 × 10−1 mol/L, [NaHCO3] = 7.94 × 10−2 mol/L, and 1.5 mL of water with 31.104 kGy of the γ radiation dose. The copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. The SEM analysis showed a highly nanoporous and cellular structure of the copolymer. The copolymer was used as a support for lipase immobilization. The optimization of the reaction conditions, including the pH and temperature for immobilization, on the basis of the hydrolysis of p-nitrophenyl palmitate, was carried out. An excellent efficiency for protein loading (70%) at pH 8.5 by the copolymer was observed. The results observed during the evaluation of the hydrolytic properties showed excellent activity of the bound lipase. The porous gelatin-co-PVA bound lipase was found to be stable at 75°C and pH 8.5; it displayed 2.326 ± 0.005 U/g of lipase activity. The stability and activity of the copolymer-bound lipase were also studied as a function of the time at 75°C, and the biocatalyst was found to be stable and active up to 1 h, beyond which the activity decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39622.
Dynamics of Unentangled cis-1,4-Polyisoprene Confined to Nanoporous Alumina

The dynamics of unentangled cis-1,4-polyisoprene confined within self-ordered nanoporous alumina (AAO) is studied as a function of molecular weight (5000–300 g/mol) and pore size (400–25 nm) with dielectric spectroscopy. The main effects are the pronounced broadening of both segmental and chain modes with decreasing AAO pore diameter. This suggests that the global chain relaxation is retarded on confinement. Remarkably, the distribution of relaxation times is broadened even within pores with size 50 times the unperturbed chain dimensions. The glass temperature is unaffected by confinement. These results are discussed in terms of confinement and adsorption effects. Confinement effects are negligible for the studied molecular weights. Chain adsorption, on the other hand, involves time and length scales distinctly different from the bulk that can account for the experimental findings.
Liquid hydrocarbon fuels from cellulosic feedstocks via thermal deoxygenation of levulinic acid and formic acid salt mixtures

Formic acid is demonstrated as a hydrogen source in a solid reaction system by first stabilizing the acid as a calcium salt which then decomposes at temperatures of relevance in pyrolytic reactions. High yields of deoxygenated hydrocarbons are produced by thermal decomposition of formic and levulinic acid mixtures where the optimum feed stoichiometry is consistent with that of cellulose hydrolysis and dehydration. The method promises a high-yield, robust, low-pressure, non-catalytic route for converting biomass hydrolyzates to hydrocarbon mixtures which are similar to petroleum crude oils.
Highly stable anion exchange membranes based on quaternized polypropylene

A series of novel quaternized polypropylene (PP) membranes with ‘side-chain-type’ architecture was prepared by heterogeneous Ziegler–Natta catalyst mediated polymerization and subsequent quaternization. Tough and flexible anion exchange membranes were prepared by melt-pressing of bromoalkyl-functionalized PP (PP-CH2Br) at 160 °C, followed by post-functionalization with trimethylamine (TMA) or N,N-dimethyl-1-hexadecylamine (DMHDA) and ion exchange. By simple incorporation of a thermally crosslinkable styrenic diene monomer during polymerization, crosslinkable PP-AEMs were also prepared at 220 °C. PP-AEM properties such as ion exchange capacity, thermal stability, water and methanol uptake, methanol permeability, hydroxide conductivity and alkaline stability of uncrosslinked and crosslinked membranes were investigated. Hydroxide conductivities of above 14 mS cm−1 were achieved at room temperature. The crosslinked membranes maintained their high hydroxide conductivities in spite of their extremely low water uptake (up to 56.5 mS cm−1 at 80 °C, water uptake = 21.1 wt%). The unusually low water uptake and good hydroxide conductivity may be attributed to the “side-chain-type” structures of pendent cation groups, which probably facilitate ion transport. The membranes retained more than 85% of their high hydroxide conductivity in 5 M or 10 M NaOH aqueous solution at 80 °C for 700 h, suggesting their excellent alkaline stability. It is assumed that the long alkyl spacer in the ‘side-chain-type’ of 9 carbon atoms between the polymer backbone and cation groups reduces the nucleophilic attack of water or hydroxide at the cationic centre. Thus, PP-based AEMs with long “side-chain-type” cations appear to be very promising candidates with good stability for use in anion exchange membrane fuel cells (AEMFCs).
Filtration Performance Against Nanoparticles by Electrospun Nylon-6 Media Containing Ultrathin Nanofibers

We investigate the formation of ultrathin nanofibers (UNFs) with diameters below 20 nm by electrospinning Nylon-6 solution with various processing parameters. It is found that the UNF density and morphology are highly dependent on the solution concentration and age, collecting distance, and ambient humidity. The sequence that ribbon-like fibers are stretched by the electric force, followed by rapid phase separation of the splitting film is proposed as a formation mechanism of the UNFs. Based on the morphological study, a model of hexagonal nets is developed in order to estimate the filtration efficiency by the UNF structure. The estimated efficiency due to the UNFs is then combined with the contribution from the un-split nanofibers (NFs) to compute the total filtration efficiency and pressure drop for each of the electrospun media by applying a layered multiple zone model. The filtration performance of the electrospun media against nanoparticles is evaluated using the quality factor and specific filtration performance index, weighed against the pressure drop and basis weight of the media, respectively. Our results show UNFs are advantageous when high filtration efficiency is required and low weight is desired and/or little space is available for the filter media. Copyright 2014 American Association for Aerosol Research
One-dimensional particle models for heat transfer analysis

For a better understanding of Spitzer-Härm closure restrictions and for estimating the relevancy of this expression when collisionnality decreases, an effort is done in developing simple models that aim at catching the physics of the transition from conductive to free-streaming heat flux. In that perspective, one-dimensional particle models are developed to study heat transfer properties in the direction parallel to the magnetic field in tokamaks. These models are based on particles that carry energy at a specific velocity and that can interact with each other or with heat sources. By adjusting the particle dynamics and particle interaction properties, it is possible to generate a broad range of models of growing complexity. The simplest models can be solved analytically and are used to link particle behavior to general macroscopic heat transfer properties. In particular, some configurations recover Fourier's law and make possible to investigate the dependance of thermal conductivity on temperature. Besides, some configurations where local balance is lost require defining non local expression for heat flux. These different classes of models could then be linked to different plasma configurations and used to study transition from collisional to non-collisional plasma.
A Quantum Molecular Dynamics Simulation Study of the Initial Hydrolysis Step in Sol−Gel Process

The dynamic behavior of the hydrolysis reaction of Si(OCH3)4 under neutral, basic, and acidic conditions was investigated, for the first time, at the atomic level with short time intervals using a novel tight-binding quantum chemical molecular dynamics program “Colors”. The initial parameters required for the computation were determined completely on the basis of the first principles density functional calculations using Amsterdam density functional program. The simulation results of this study clearly indicate that a flank-side attack mechanism is favored, in all the three cases, for the hydrolysis process, and pentacoordinate silicon intermediates are easy pathways for the displacement of −OCH3 by −OH on silicon. Moreover, the presence of the acid or the base as catalyst promotes the hydrolysis by rapid formation of Si−OH bond in comparison to the hydrolysis under neutral condition. Furthermore, in the case of the latter condition, it was observed that the proton oscillates between −OH and −OCH3 before .