Miracle-dz/UniFAR-FTUs huggingface dataset:
Mechanistic aspects of Pt-modified β-NiAl alloy oxidation

Abstract The effects of Pt addition (5, 10 and 15 at.%) on the high temperature oxidation behaviour of the intermetallic compound β-NiAl were studied at 1150°C under both isothermal and thermal cycling conditions. The scale growth mechanism was assessed using two-stage oxidation exposures with 18O2 as a tracer in conjunction with high-resolution secondary ion mass spectrometer analysis of isotopic distributions. The scale morphologies were further characterized using secondary electron microscopy, Pt was found to reduce slightly the scale growth rate and improve considerably its resistance to spallation but it did not affect the sequence of scale development. Instead, it slowed the rate at which the scale developed. The α-Al2O3 scales that were eventually established were duplex in structure, consisting of a compact inner layer and a thinner outer layer. This outer layer consisted of ridges and grew by the coarsening of these and/or by a dislocation climb mechanism.
Impedance Characteristics of the Nanoporous Honeycomb Diamond Electrodes for Electrical Double-Layer Capacitor Applications

Nanoporous boron-doped diamond films with highly ordered pore structures and various pore dimensions, fabricated by oxygen plasma etching of polished polycrystalline diamond films through porous alumina masks, were characterized using electrochemical impedance measurements. The porous structures exhibited wide electrochemical potential windows (2.46-2.70 V), although somewhat less than that for the as-deposited films (3.04 V) because of surface damage due to the oxygen plasma treatment. A film of pore diam 400 nm and pore depth 3 μm exhibited a 400-fold increase in the capacitance in comparison to an as-deposited surface film. A film with 30 nm diam pores showed little enhancement in the capacitance at useful frequencies due to the high pore impedance. Impedance measurements carried out at −0.5 V vs. Ag/AgCl indicated a faradaic reaction, most likely hydrogen evolution. Although the dc current was small (ca. 3.0 μA cm−2 real area for the 60 nm honeycomb), it represents a pathway for charge leakage, limiting the negative potential limit for charge storage. However, similar limits were also observed for a representative acetylene black and activated carbon. The as-deposited diamond and nm honeycomb exhibited significantly higher effective potential limits for anodic charging due to the lack of surface oxidation current. This allows more charge to be stored per unit capacitance for diamond materials than for graphitic carbons. Due to the surface damage, the honeycomb sample did not store as much charge per unit capacitance as the as-deposited sample. © 2001 The Electrochemical Society. All rights reserved.
Study of the Volatile Compounds and Amino Acid Profile in Bacillus Fermented Castor Oil Bean Condiment

Bacillus subtilis was used as a monoculture starter for the production of three different fermented castor oil bean condiments: B1 ( 0% NaCl/Lime), B2 (2% NaCl), B3 (3% Lime). The volatile components of the three samples were determined using Gas –Chromatography / Mass Spectrometry (GC-MS) while High Performance Liquid Chromatography (HPLC) was used in the study of the amino acid contents. A total of seventeen volatile constituents were identified in the fermented castor oil bean samples using GC-MS. The compounds identified were of various types: acids, esters, alcohols, furans, ketones and others. However, acids were found to be the dominant constituent group followed by esters. Results from the amino acid analysis shows the three fermented castor oil bean samples contained sufficient amount of amino acids. The essential amino acids were in the range of 42.22 – 54.17% for EAA7 and 63.76 – 73.82% for EAA10 of total Free Amino Acids with the most abundant being tryptophan, isoleucine and phenyalanine. Bitter taste was observed as the predominant taste followed by sweet taste and tasteless amino acids. MSG-like taste was slight with B1:1.624 µg/ml, B2: 1.069 µg/ml and B3: 0.881 µg/ml. It is suggested that the desirable taste of ogiri from castor oil bean is formed by interactions between the amino acid and volatile components analyzed in this study.
Star-shaped magnetite@gold nanoparticles for protein magnetic separation and SERS detection

A novel synthetic methodology for star shaped gold-coated magnetic nanoparticles is reported. The coating is performed in two steps: formation of gold nuclei at the surface of magnetite nanoparticles followed by growth of the gold nuclei into a complete star shaped shell. The star-shaped gold-coated magnetic nanoparticles thus obtained preserve the magnetic properties of the precursor magnetite nanoparticles, e.g. they can be easily separated with a magnet. In addition, the gold coating provides interesting optical properties while simultaneously allowing for biofunctionalization that may be advantageous for biological applications, such as (bio)detection via surface-enhanced Raman spectroscopy (SERS). As a proof-of-concept, a capping agent terminated with a nickel(II)-nitrilotriacetate group showing high affinity for histidine was used to modify the surface of the nanoparticles. The resulting star-shaped nanoparticles were used to selectively capture histidine-tagged maltose-binding protein from a crude cell extract. Finally, the performance of star shaped gold-coated magnetic nanoparticles as SERS platforms was demonstrated through the detection of Raman active dye (Astra Blue).
Preceramic polymer‐derived SiOC fibers by electrospinning

Silicon oxycarbide (SiOC) fibers with different chemical compositions were successfully fabricated by electrospinning a mixture of polyvinylpyrrolidone (PVP) and commercially available polymethylsilsesquioxane (MK) or polymethylphenylsilsesquioxane (H44) preceramic polymers, followed by cross-linking and pyrolysis at 1000°C in Argon. The influence of the processing procedure (solvent selection, cross-linking catalyst and additives) on the morphology of the produced fibers was investigated. For the MK/isopropanol system, the introduction of 20 vol% N,N-dimethylformamide (DMF) enabled to decrease the diameter of the as-spun fibers from 2.72 ± 0.12 μm to 1.65 ± 0.09 μm. For the H44/DMF systems, beads-free fibers were obtained by adding 50 vol% choloroform. After pyrolysis, the resultant SiOC fibers derived from MK and H44 resins possessed uniform morphology, with an average diameter of 0.97 ± 0.07 μm and 1.07 ± 0.08 μm, respectively. Due to their different chemical compositions, the MK-derived and H44-derived SiOC ceramic fibers could find different potential applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39836.
Electrochemical Cholesterol Sensor Based on Tin Oxide‐Chitosan Nanobiocomposite Film

A chitosan (CS)-tin oxide (SnO2) nanobiocomposite film has been deposited onto an indium-tin-oxide glass plate to immobilize cholesterol oxidase (ChOx) for cholesterol detection. The value of the Michaelis–Menten constant (Km) obtained as 3.8 mM for ChOx/CS-SnO2/ITO is lower (8 mM) than that of a ChOx/CS/ITO bioelectrode revealing enhancement in affinity and/or activity of ChOx towards cholesterol and also revealing strong binding of ChOx onto CS-SnO2/ITO electrode. This ChOx/CS-SnO2/ITO cholesterol sensor retains 95% of enzyme activity after 4–6 weeks at 4 °C with response time of 5 s, sensitivity of 34.7 μA/mg dL−1 cm2 and detection limit of 5 mg/dL.
Self‐initiating performance of maleic anhydride on surface photografting polymerization

Maleic anhydride (MAH) was photografted onto low-density polyethylene (LDPE) films with a grafting efficiency of about 70% in the absence of a photoinitiator. The self-initiating performance was attributed to a mechanism of abstracting hydrogen atoms from LDPE chains by excited MAH dimers. The supporting experimental results were as follows: (1) the far-UV radiation (200-300 nm) was indispensable for the graft polymerization and 2) the crosslinking reaction of LDPE inevitably accompanied the grafting of MAH. In addition, the initiation performance of MAH was further confirmed by surface photografting of acrylic acid in the presence of MAH, where MAH was used as the photoinitiator.
Fluctuations, temperature, and detailed balance in classical nucleation theory

The role of temperature in classical nucleation theory is examined. It is shown that while even small clusters are assigned a temperature in the classical theory, this must be a fluctuating quantity. Stochastic simulations of cluster evaporation and growth are presented to track the temperature fluctuations in time. The relation 〈‖δT‖2〉=kT20/Cν for the mean square temperature fluctuation is confirmed, where k is the Boltzmann constant, Cν is the cluster heat capacity, and T0 is the bath temperature. For small capillary drops (50–100 molecules), the resulting rms temperature fluctuations of 10°–20° might be expected to have a significant effect on the nucleation rate. However, the simulations reveal a cluster temperature distribution that is centered several degrees below T0. A theory is presented to explain this effect. To first order, which includes Gaussian fluctuations of the cluster temperature T, we find that the effective temperature for cluster evaporation is T−h/2Cν, where h is the latent heat. Th.
Three-dimensional structured sponge with high oil wettability for the clean-up of oil contaminations and separation of oil–water mixtures

Oil spills not only result in extensive economic losses but also damage marine ecological environments. A series of materials with special wettability are investigated for the separation of oil–water mixtures. However, few studies have investigated the adsorption behaviors of sponges to crude oil (high viscosity). To solve the restrictions of high viscosity oil absorption, low oil absorption rate and oil–water emulsion separation of oil absorption materials, a superhydrophobic and superoleophilic polyurethane (PU) sponge was synthesized via an environmentally friendly surface grafting of a polymer molecular brush. This grafted sponge exhibited high oil absorption rate because of the expansion in oil and collapse in water of the polymer molecular brushes. The grafted PU sponge also possessed high absorption capacity (23 times of the self weight), high oil retention (93%), high mechanical strength and good recyclability (more than 400 times). We anticipate that the grafted sponge will have numerous applications and will show outstanding performance on a larger scale. A quick clean-up of marine spilled oil/organic solvents and the separation/recycling of an oil–water mixture/emulsion can also be achieved.
Preparation and characterization of poly(ethylene terephthalate) copolyesters and fibers modified with sodium-5-sulfo-bis-(hydroxyethyl)-isophthalate and poly(ethylene glycol)

New copolyesters were successfully prepared with SIPE and PEG units designated as cationic dyeable polyester and easy cationic dyeable polyester. The number average molecular weight of PEG unit is 6000 (abbreviated as PEG6000). Corresponding copolyesters were spun into fibers with melt spinning method. Chemical and crystalline structures were characterized by the NMR and WAXD measurement, and thermal properties were tested by Differential Scanning Calorimetry and Thermogravimetric Analysis, respectively. NMR experimental results indicated the actual molar ratio of comonomers was basically consistent with the correlative feed ratio. WAXD results showed that crystalline structures of prepared copolyesters were similar to that of Poly(ethylene terephthalate). Moreover, the glass transition temperature, melting temperature, and thermal degradation temperature were found to decrease with the increase in weight ratio of PEG6000 units since the incorporation of higher PEG6000 content brought more ether bonds into molecular chains, which increased the asymmetry and irregularity of molecular chains and led to lower crystallinity. Besides, when content of PEG6000 increased, the breaking tenacity and initial modulus were reduced, yet elongation at break enhanced. It suggested that PEG6000 segments reduced the symmetry of molecular chains and decreased the orientation degree of fibers. In addition, because the incorporation of higher weight percentage of PEG6000 led to more hydroxyl end groups and ether bonds in molecular chains, the moisture regain of fibers increased, manifesting fibers had better hydrophilicity with increasing weight ratio of PEG6000 components.
Fully adaptive algorithms for multivariate integral equations using the non-standard form and multiwavelets with applications to the Poisson and bound-state Helmholtz kernels in three dimensions

We have developed and implemented a general formalism for fast numerical solution of time-independent linear partial differential equations as well as integral equations through the application of numerically separable integral operators in d ≥ 1 dimensions using the non-standard (NS) form. The proposed formalism is universal, compact and oriented towards the practical implementation into a working code using multiwavelets. The formalism is applied to the case of Poisson and bound-state Helmholtz operators in d = 3. Our algorithms are fully adaptive in the sense that the grid supporting each function is obtained on the fly while the function is being computed. In particular, when the function g = O f is obtained by applying an integral operator O, the corresponding grid is not obtained by transferring the grid from the input function f. This aspect has significant implications that will be discussed in the numerical section. The operator kernels are represented in a separated form with finite but arbitrary precision using Gaussian functions. Such a representation combined with the NS form allows us to build a sparse, banded representation of Green’s operator kernel. We have implemented a code for the application of such operators in a separated NS form to a multivariate function in a finite but, in principle, arbitrary number of dimensions. The error of the method is controlled, while the low complexity of the numerical algorithm is kept. The implemented code explicitly computes all the 22d components of the d-dimensional operator. Our algorithms are described in detail in the paper through pseudo-code examples. The final goal of our work is to be able to apply this method to build a fast and accurate Kohn–Sham solver for density functional theory.
Solvent-induced deactivation of singlet oxygen: additivity relationships in nonaromatic solvents

Les mesures du declin de la luminescence IR resolue dans le temps a partir de solutions aerees de porphyrines ont permis de determiner la duree naturelle de vie de O 2 1 Δg dans de nombreux solvants. La constante de vitesse K Δ a pu etre calculee et comparee aux valeurs experimentales. Dans beaucoup de cas on trouve un bon accord
Learning from Diatoms: Nature's Tools for the Production of Nanostructured Silica

Diatoms are eukaryotic, unicellular algae that are ubiquitously present in almost any water habitat on earth. Diatoms dominate phytoplankton populations and algal blooms in the oceans. They are responsible for about 25 % of the world's net primary production. Apart from this ecological significance, diatoms are mainly known for the intricate geometries and spectacular patterns of their silica‐based cell walls. These patterns are species specific. They are precisely reproduced in each generation documenting a genetic control of this biomineralization process. Biogenesis of the diatom cell wall is considered to be a paradigm for the controlled production of nanostructured silica. Biochemical studies demonstrated that diatom biosilica is a composite material containing zwitterionic proteins (silaffins) and long‐chain polyamines in addition to silica. Functional studies indicate a crucial role of these organic components in guiding silica precipitation as well as in the formation of species‐specific nanopatterns. These activities can be explained by molecular self‐assembly and phase‐separation processes. Moreover, diatom cell walls also exhibit very exciting properties from the physical point of view: they are extremely stable and they may act as photonic crystals.
Separation and concentration of bilberry impact aroma compound from dilute model solution by pervaporation

BACKGROUND: In the present work, the flavor compounds of natural juice of bilberries were qualitatively analyzed by GC-MS, leading to the identification of trans-Hex-2-en-1-ol as one of the major ‘impact aroma’ compounds of this fruit. The pervaporation of trans-Hex-2-en-1-ol from diluted aqueous solutions was studied using commercial polydimethylsiloxane (PDMS) capillary membranes. The influences of solvent composition (water/ethanol mixtures), initial concentration of the aroma compound, flow rate and temperature of the feed were studied. RESULTS: High selectivity of the PDMS membrane towards the aroma compound was obtained, leading to enrichment factors in the range 100 < β < 200. Mass transfer resistance was found to be located in the pervaporation membrane. Experimental data showed a linear dependency of the permeation flux of trans-Hex-2-en-1-ol on the differences in partial pressures of the compound across the pervaporation membrane. The permeability coefficient of the PDMS membrane to the transport of trans-Hex-2-en-1-ol was calculated as Pm, Hex(50 °C) = 7.62 × 10−11 mol m−1 s−1 Pa−1. CONCLUSION: The membrane used was found to be very selective toward trans-Hex-2-en-1-ol. A model based on the solution-diffusion mechanism was applied. The mass transfer parameters needed for the design of a pervaporation process for aroma compound recovery were obtained. Copyright © 2008 Society of Chemical Industry
Self-assembly of cholesterol DNA at liquid crystal/aqueous interface and its application for DNA detection

In this letter, we report a strategy of detecting the DNA targets by using a thin layer of self-assembled cholesterol-labeled DNA probes at the liquid crystal (LC)/aqueous interface. When the system is exposed to 51 μg/ml of complementary DNA targets, the optical appearance of LC shows a continuous change from dark to bright under the crossed polars within 15 min. No obvious change can be observed when the system is exposed to one or two base-pair mismatch DNA targets. This system provides a principle for label-free and real-time detection of DNA targets without any fluorescent labeling.
Anaerobic Bioremediation of Hexavalent Uranium in Groundwater

Uranium contamination of groundwater from mining and milling operations is an environmental concern. Reductive precipitation of soluble and mobile hexavalent uranium (U(VI)) contamination to insoluble and immobile tetravalent uranium (U(IV)) constitutes the most promising remediation approach for uranium in groundwater. Previous research has shown that many microorganisms are able to catalyze this reaction in the presence of suitable electron-donors. The purpose of this work is to explore lowcost, effective alternatives for biologically catalyzed reductive precipitation of U(VI). Methanogenic granular sludge from anaerobic reactors treating industrial wastewaters was tested for its ability to support U(VI)-reduction. Due to their high microbial diversity, methanogenic granules displayed intrinsic activity towards U(VI)-reduction. Endogenous substrates from the slow decomposition of sludge biomass provided electron-equivalents to support efficient U(VI)-reduction without external electrondonors. Continuous columns with methanogenic granules also demonstrated sustained reduction for one year at high uranium loading rates. One column fed with ethanol, only enabled a short-term enhancement in the uranium removal efficiency, and no enhancement over the long term compared to the endogenous column. Nitrate, a common co-contaminant of uranium, remobilized previously deposited biogenic U(IV). U(VI) also caused inhibition to denitrification. An enrichment culture (EC) was developed from a zero-valent iron (Fe⁰)/sand packed-bed bioreactor. During 28 months, the EC enhanced U(VI)-reduction rates by Fe⁰ compared with abiotic Fe⁰ controls. Additional experiments indicated that the EC prevented the passivation of Fe⁰ surfaces through the use of cathodic H₂ for the reduction of Fe(III) in passivating corrosion mineral phases (e.g. magnetite) to Fe²⁺. This contributed to the formation of secondary minerals more enriched with Fe(II), which are known to be chemically reactive with U(VI). To determine the toxicity of U(VI) to different populations present in uranium contaminated sites, including methanogens, denitrifiers and uranium-reducers, experiments were carried out with anaerobic mixed cultures at increasing U(VI) concentrations. Significant inhibition to the presence of U(VI) was observed for methanogens and denitrifiers. On the other hand uranium-reducing microorganisms were tolerant to high U(VI) concentrations. The results of this dissertation indicate that direct microbial reduction of U(VI) and microbially enhanced reduction of U(VI) by Fe⁰ are promising approaches for uranium bioremediation.
New HPLC Techniques for Proteomics Analysis: A Short Overview of Latest Developments

During the last ten to fifteen years a huge development in the field of analytical techniques used for deciphering the complex nature of the proteome took place. Instrumentation and methods development for sample cleanup, fractionation, preconcentration, chromatographic separation, and detection become affordable to a broad range of laboratories and new, exciting methods for both separation and detection were published and applied. Newly developed techniques and equipment for separation and detection, such as high pressure nano-HPLC and new techniques for multidimensional HPLC separation, enabled proteomics to experience dynamic growth and enter new paths. Furthermore, proteomics starts entering the “real life” and it is increasingly applied for clinical diagnostics and follow-up of patient's status during the treatment. For any proteomic analysis, one of the most important and sometimes the most difficult task is the separation of the complex mixtures of proteins or peptides prior to their detection and data analysis. This review describes some aspects and limitations of HPLC, both multidimensional and one-dimensional, in proteomics research without attempting to discuss all available HPLC methods, their benefits and shortcomings which would need far more space than available here.
Surface Modification of Polyurethanes with Covalent Immobilization of Heparin

Thrombus formation and blood coagulation is a major problem associated with blood contacting products such as catheters, vascular grafts, arteries, artificial hearts and heart valves. An intense research is being conducted towards the synthesis of new hemocompatible materials and modifications of surfaces with biological molecules. In this study, polyurethane (PU) films were synthesized in medical purity from diisocyanate and polyol without using any other ingredients and their surfaces were modified by covalent immobilization of heparin. Two types of heparin, unfractionated (UFH) and low molecular weight heparin (LMWH), were immobilized to investigate their effect on cell adhesion. The surface properties of the modified PUs were examined with ESCA, ATR-FTIR and AFM. ESCA results demonstrated sulfur peaks indicating the presence of heparin and AFM results showed the alteration of surface structure after coating with heparin. Cell adhesion studies were conducted with heparinized whole human blood. The surfaces of the UFH immobilized films resulted in lesser red blood cell adhesion in comparison to LMWH demonstrating strong anti-thrombogenic activity of the latter.