Miracle-dz/UniFAR-FTUs huggingface dataset:
Joining of silicon carbide by a heat-resistant phosphate adhesive

In this paper, SiC was bonded with a phosphate inorganic adhesive prepared from H3PO4 and Al(OH)3 as the matrix and Si and B4C as the inorganic fillers. The properties of the obtained adhesive were analyzed by XRD, TG-DSC, IR, shear strength tests and SEM. The results showed that the phosphate adhesive exhibited outstanding heat-resistant properties and excellent bonding strength. The addition of B4C could greatly improve the adhesive's mechanical properties due to the formation of borosilicate glass and the volume compensation came from B4C's oxidation. The shear strength of bonded specimens could be up to about 10 MPa after heat treatment at 1300 °C, attributed to the generation of mullite and borosilicate as well as the reasonable compensation for the adhesive's volume.
A Multiplex PCR‐Based Assay for the Detection of Genetically Modified Soybean

Abstract The detection of nucleotide sequences specific for genetically modified organisms (GMOs) in raw and processed food is based on different technological strategies, such as the extraction of DNA and the amplification by polymerase chain reaction (PCR), which allow to obtain qualitative and quantitative information. We developed a multiplex PCR‐based DNA assay for simultaneously detecting multiple target sequences in genetically modified (GM) soybean (Roundup Ready™). Internal control target (lectin gene) was included both to assess the efficiency of all reactions and eliminating any false negatives. The post‐PCR analysis was carried out by 2.5% agarose gel electrophoresis followed by ethidium bromide staining and densitometric analysis. The multiplex PCR method, showing high sensitivity and specificity, was tested on DNA extracted from certified reference samples containing GM soybean, and from food samples (feeds, food supplements, etc.). Comparison of this method with a quantitative evaluation, carried out by real‐time PCR, suggests a possible utilization of the multiplex approach for semi‐quantitative determinations. The method reported in this work can considerably reduce the time and the costs of the GM soybean detection, especially in the screening of a large number of food samples. †This paper is dedicated to Prof. Corradino Motti sorrowfully missed on May 1, 2001.
Soil amendment with agro‐industrial byproducts: molecular‐chemical compositions and effects on soil biochemical activities and phosphorus fractions

Environmental pollution by agro-industrial byproducts in developing countries can be alleviated by recycling into soils. However, little is known about their chemical composition and impact on soil fertility. Therefore, the objectives of the present study were (1) to characterize the molecular-chemical composition of dry (COD) and wet (COW) coffee, sisal (SIS), barley malt of brewery (BEB), and sugarcane processing (FIC) byproducts, and filter cakes of linseed (LIC) and niger seed (NIC) and (2) to evaluate their effects on respiration, pH, enzyme activities, and P fractions of a tropical soil. The agro-industrial byproducts significantly differed in their concentrations of plant nutrients and organic-matter compositions. The highest proportions of lipids, phenols + lignin monomers, and alkylaromatics were observed in COD, N-containing compounds in COW, sterols in FIC, peptides in LIC, suberin in SIS, and fatty acid in COW and FIC. The application of the byproducts at the rate of 40 kg P ha–1 (1.1 to 13.2 g C [kg soil]–1) significantly (p LIC > BEB > COW > SIS > FIC > COD.
Formation and Properties of a Continuous Crystallinity Series of Synthetic Ferrihydrites (2- to 6-line) and their Relation to FeOOH Forms

Ferrihydrite is a poorly crystalline Fe oxide of which 2-(XRD)line and 6-line varieties are commonly used in experiments, although species with intermediate numbers of peaks have been found in nature. To simulate nature, we synthesized two continuous series of ferrihydrites with between 2 and 6–7 peaks at room temperature in two different ways: (1) by varying the rate of hydrolysis of an Fe(NO3)3 solution (HR series); and (2) by oxidizing an FeCl2 solution containing up to 73 mmol Si/L (Si series), both at pH 7. Mössbauer spectra at 4.2 K showed that the ferrihydrites of the HR series had a constant magnetic hyperfine field (Bhf) at 4.2 K of 48.8 T whereas Bhf in the Si series dropped from 49.4 to 46.7 T as the Si content of the ferrihydrites increased from 0 to 74.7 g/kg of Si. Temperature scans between 4 and 170 K illustrate that the magnetic order breaks down at a temperature which is lower the higher the hydrolysis rate and the Si concentration in the ferrihydrite.
HPLC Determination of Pitavastatin Calcium in Pharmaceutical Dosage Forms

A simple, sensitive, reliable and rapid reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of pitavastatin calcium using paracetamol as internal standard. The chromatographic system consisted of Shimadzu LC-10ATVP Pump, SPD-M10 AVP with PDA detector. Separation was achieved on the phenomenex C 18 (250 x 4.60), 5 μ particle size column in isocratic mode at room temperature. The sample was introduced through an injector valve with a 20 μl, sample loop. 0.5% Acetic acid: Acetonitrile 35:65 (%, v/v), was used as mobile phase with flow rate of 1 ml/min. UV detection was performed at 245 nm. A calibration graph was plotted which showed a linearity range between 1-5 μg/ml with the correlation coefficient of 0.9986. The LOD was 5 ng/ ml, while the LOQ was 20 ng/ml. Validation studies revealed the method is specific, rapid, reliable, and reproducible. To study the validity of the method, recovery studies and repeatability studies were carried out using the same optimum conditions. The system suitability studies were also calculated which includes column efficiency, resolution, capacity factor and peak asymmetrical factor. Therefore the proposed method is reliable, rapid, precise and selective so may be used for the quantitative analysis of pitavastatin calcium.
Mixed Solvents for Morphology Control of Organic Solar Cell Blend Films

Poly(3-hexylthiophene) (P3HT) and fullerene derivative blend films formed by spin-coating from mixtures of ethanol and chloroform as solvent were studied. Compared with the blend films made from chloroform alone, films made with increasing ethanol concentration in the solvent showed greater degrees of P3HT crystallinity and increased phase segregation of the polymer and fullerene as observed by changes to the absorption spectra, photoluminescence spectra and optical microscope pictures.
Direct visualization of microstructures in hydrophobically modified polyacrylamide aqueous solution by environmental scanning electron microscopy

Environmental scanning electron microscopy (ESEM) is an improved technique which permits the observation of samples in their native state, requiring neither sample preparation nor surface coating, and so avoids losing the original characteristics of the observed specimens. By use of a differential pumping aperture system and a secondary electron detector, the environmental conditions in the sample chamber can be varied and accommodated to the properties of the samples. This newly developed technique is used in this work to characterize the microstructures of hydrophobically modified polyacrylamide (HMPAM) and its unmodified precursor in aqueous solution. The microstructures were directly visualized by sublimation of the ice in freeze-dried samples. It is found that three-dimensional network structures spread throughout the whole solution for both the modified and unmodified polymers when the polymer concentration is equal to or higher than the polymer critical association concentration (CAC); when the polymer concentration is below the CAC, a sparse network structure could be seen in the solutions of modified polymer, whereas no such phenomenon is found in unmodified polymer solutions. The network units of the microstructures in the solutions of modified polymer are displayed as regularly distributed hexagons, while those of unmodified polymer appear as irregular circles. The observed results are interpreted by a proposed association model.
Experimental evaluation of a scanning tunneling microscope‐microlens system

This paper presents the results of the first successfully fabricated scanning tunneling microscope (STM) aligned field emission (SAFE) microsource. SAFE sources have been shown to produce 2–3 orders of magnitude improvement in brightness over conventional field‐emission sources. Lens electrodes were fabricated from 1‐μm thick silicon membranes by electron‐beam lithography and reactive‐ion‐beam etching. Two‐element microlenses were tested in an ultrahigh vacuum (UHV) chamber with a piezo mounted tungsten tip and a dual feedback system. The sources demonstrated stable emission for periods of hours at beam energies of up to 1 kV. Measurement of the virtual source position showed good agreement with calculated values.
Temperature-Programmed Desorption Studies of n-Alkane Derivatives on Graphite: Desorption Energetics and the Influence of Functional Groups on Adsorbate Self-Assembly

Temperature programmed desorption (TPD) studies have been performed to determine the influence of functionalization on the desorption of n-alkanes from inert substrates. Monolayer and multilayer desorption was investigated for a set of six 1-bromoalkanes, six alkanoic acids, and four 2-bromoalkanoic acids adsorbed on the basal plane of highly-oriented pyrolytic graphite (HOPG). Full activation of the substrate surface for monolayer adsorption required annealing temperatures of approximately 700 K. Molecular desorption from physisorbed mono- and multilayers was found to exhibit first- and zeroth-order kinetics, respectively, with no measurable dependence of the activation energy on coverage. A Redhead analysis of monolayer desorption signals uncovered a profound influence of alkane functional groups on the desorption barrier. As compared with the case of unfunctionalized n-alkanes, the desorption energies of all derivative species studied here exhibit a reduced chain length dependence in conjunction with a.
Positronium Annihilation in Molecular Substances

The behavior of the Ps atom in molecular substances, particularly liquids, is investigated. The pickoff rates of o‐Ps in various liquid compounds are found to have a simple empirical relationship to the values of the surface tension of the liquids. The relationship is found to have a theoretical foundation. The Ps atom is highly localized in a cavity created by the balance of various molecular forces inside the liquid. From the above relationship, other simple relationships between the pickoff rates of o‐Ps and the various properties of the medium, e.g., polarizability, cohesive energy density, etc., and the temperature or pressure changes can be derived and explained. The diffusion of o‐Ps is discussed. A similar approach can also be used for molecular solids.
Microwave-Assisted Cationic Ring-Opening Polymerization of 2-Oxazolines: A Powerful Method for the Synthesis of Amphiphilic Triblock Copolymers

We report on the first successful example of the preparation of triblock copolymers via a cationic ring-opening polymerization procedure. A library of 30 triblock copolymers was prepared from 2-methyl-, 2-ethyl-, 2-nonyl-, and 2-phenyl-2-oxazoline in a single-mode microwave reactor. The polymers exhibited narrow molecular weight distributions and showed only minor deviations from the targeted monomer ratio of 33:33:33. The glass-transition temperature of the triblock copolymers spanned the range from 50 to 100 °C depending on the incorporated monomers. The micellization behavior was investigated for some amphiphilic triblock copoly(2-oxazoline)s containing two hydrophilic and one hydrophobic blocks. The size of the micelles was larger when the hydrophobic block is located at one end of the triblock copoly(2-oxazoline)s, as measured by atomic force microscopy and dynamic light scattering.
Simultaneous determination of anions and divalent cations using ion chromatography with ethylenediaminetetraacetic acid as eluent

A method is described for the simultaneous determination of Cl–, NO3–, SO42–, Mg2+ and Ca2+ ions using ion chromatography with 0.0015 mol l–1 ethylenediaminetetraacetic acid as eluent at pH 4.8, with ultraviolet (UV)(200 nm) and conductivity detectors in series. Detection limits for these ions [2s(n= 15) for a 1 + 99 dilution of the standard solution] are 6, 0.8, 4, 20 and 10 ng, respectively; a 200 µl aliquot was used for all determinations. In general, greater sensitivity is obtained for Cl–, SO42– and Mg2+ using conductivity detection, whereas for NO3– and Ca2+, UV detection affords a lower detection limit. The greater sensitivity for NO3– and Ca2+ compared with literature methods is due to a shorter wavelength for UV detection being accessible because of the lower absorbance of the eluent at pH 4.8. For Mg2+, partial protonation of the complex at this pH is thought to increase its equivalent conductance and hence sensitivity to conductivity detection. Analyses were made of four reference waters, which were within the 95% confidence interval for all analytes and for both detection modes. The calibration graphs were linear (r > 0.99) over at least three orders of magnitude of concentration from the detection limit, except for the UV detection of NO3–(r= 0.967). The method is directly applicable to both fresh- and sea-water samples, and was tested using a number of samples from natural and artificial water bodies near Jabiru, Northern Territory, Australia. Reproducible analyses for all analytes were obtained for these freshwater samples, with alkalinities in the range 1–180 mg l–1 CaCO3, after storage at 4 °C for 1 month. All peaks are well separated and no common ions interfere with any analyte.
Evaluation of Polymeric Membranes for Gas Separation Processes: Poly(ether- b -amide)(PEBAX® 2533) Block Copolymer

The development of polymeric membranes for gas separations has provided an alternative to traditional energy-intensive processes, especially for hydrocarbon separations. Material studies of the membrane can provide insights to its formation and modification. Gas permeation behaviour through two types of polymeric membrane material is investigated herein. Though the main objective of our investigation was to determine the hydrocarbon gas permeation properties of poly(etherb-amide) PEBAX 2533 copolymer membranes over a range of operating temperatures and pressures, we first tested a poly(ethylene oxide) (PEO) membrane for permeability of ethane and ethylene. The screening results from the tests of PEO membranes containing silver salts, indicate that although PEO membranes may possess high olefin/paraffin selectivity through facilitated transport, difficult membrane preparation and unstable structure remain major obstacles to their commercial use. However, the knowledge acquired on preparation technique and permeability testing from these trials was carried over to our study of PEBAX R 2533 membranes. Permeability coefficients were determined at temperatures ranging from 25 C to 75C, and pressures from 25 psig to 200 psig for ethane, ethylene, nitrogen, propane, propylene, and carbon dioxide. The PEBAX R 2533 membranes showed high organic gas permeabilities. Plasticization effects on the membrane were pronounced with propane and propylene at elevated pressure (100 psig). Activation energies of permeation (E p) were determined. E p of nitrogen is nearly constant and is the highest among gases tested in the pressure range. E p shows a linear decreasing trend as pressure increases for hydrocarbons. Relatively high selectivities (12 to 26) were observed for the polar and non-polar gas pair CO 2/N2. As temperature increased, the selectivity of CO2/N2 decreased. This study provides the groundwork for the use of PEO and PEBAX R 2533 membranes for hydrocarbon separations.
Automatic extraction–spectrofluorimetric method for the determination of imipramine in pharmaceutical preparations

The spectrofluorimetric determination of trace amounts of imipramine was carried out by liquid–liquid extraction using Erythrosine B with a flow injection system. The determination of imipramine in the range 0.12–2.80 µg ml–1 was possible with a sampling frequency of 45 h–1. The method was satisfactorily applied to the determination of imipramine in pharmaceutical preparations.
Evaluation of Forest Fire Risk with GIS

This paper uses GIS to describe and evaluate forest fire risk considering the most important factors affecting fire behavior at fine scales. The study was implemented in Yesilova Forestry Enterprise in the Mediterranean city of Kahramanmaras, Turkey. To determine an overall fire risk index for the study area, fire risk rating (extreme, high, moderate, or low) was assigned to decision variables (i.e. species composition, stand development stage, stand crown closure, slope, insolation, settlements, and roads) according to their risk potentials. Additionally, the visibility analysis of fire towers was carried out for monitoring of forests in the case study area. Finally, visibility analysis and a forest fire risk map were evaluated together for determining the efficiency of fire towers. Results indicated that more than half of the total forested area (65.7%) was classified as low category in the fire risk map. According to visibility analysis, the existing fire tower was able to monitor only 37% of forest areas; therefore, it was essential to consider new fire towers for monitoring the overall study area. After locating a potential new fire tower in the study area, it was found that about 71.8% of the area was with the visible zones of two fire towers.
Dual-microring-resonator electro-optic logic switches on a silicon chip

We report dual-microring-resonator electro-optic logic switches using two embedded injection-type p-i-n diodes with dual electrical inputs on a silicon chip. Our matrix analysis and semiconductor device numerical simulations reveal OR (NOR) function electro-optic switching for the throughput- (drop-) port transmission at a probe wavelength near the resonance of the coupled identical microring resonators. We find that upon the dual electrical digital input states (1, 0) and (0, 1), the drop-port transmissions are related by reciprocity and thereby are identical, whereas the throughput-port transmissions are not reciprocity related and thus in general are non-identical. Our characterizations of initial fabricated devices on a silicon-on-insulator substrate, however, reveal that the proposed logic operations hinge on high fabrication fidelity of the coupled microring resonators.
Electrospun nanofibers in energy and environmental applications

Nanotechnology is providing new solutions and opportunities to ensure sustainable energy and environments for the future. Materials of nanofiberous morphology are attractive to solve numerous energy and environmental issues. Nanofibers can be effectively produced by electrospinning, which is a simple and low cost technique. In addition, electrospinning allows the production of nanofibers from various materials e.g. organics and inorganics in different configurations and assemblies. This is highly beneficial for energy devices, where inorganic materials especially metal oxides can be synthesized and electrospun, improving conducting and ceramic properties. Excitonic solar cells fabricated with aligned nanofiberous metal oxide electrodes provide higher solar–electric energy conversion efficiency, whereas fuel cells made with nanofiberous electrodes enable uniform dispersion of catalysts, and thus increase electrocatalytic activity to obtain higher chemical–electric energy conversion efficiency. The nanofibers used in filtration membranes for environmental remediation, minimize the pressure drop and provide better efficiency than conventional fiber mats. The large surface area-to-volume ratio of nanofiber membranes allows greater surface adsorption of contaminants from air and water, and increases the life-time of the filtration media. This review highlights the potential and application of electrospun nanofiberous materials for solving critical energy and environmental issues.
Ground currents in single‐phase transformerless photovoltaic systems

The relative weight of the energy generated by means of renewable sources is constantly increasing. Among all these sources, the photovoltaic (PV) systems present the higher and more stable relative growth. However, the PV system is still too expensive and a significant effort is being done to increase the efficiency and reduce the cost. Concerning the PV inverters, this has lead to the elimination of the low frequency (LF) transformer that has been traditionally included. The LF transformer provides isolation from the grid but reduces the PV inverter efficiency and increases its size and cost. However, the elimination of the transformer might generate strong ground currents, which become now an important design parameter for the PV inverter. The ground currents are a function of the system stray elements. However, there is no simple model and procedure to study the common mode behavior of a PV system, which is required to analyze the ground currents. In this paper, a comprehensible model is proposed which provides a better understanding of the common mode issue in single‐phase transformerless PV systems. In addition, a procedure is developed to analyze the global performance, efficiency, grid current quality, and common mode behavior of a PV inverter as a function of its particular structure and modulation technique. Copyright © 2007 John Wiley & Sons, Ltd.
On the Structure of Bismuthsesquioxide: The α, β, γ, and δ-phase

The structures of four polymorphs of Bi2O3 were investigated by means of X-ray and neutron powder diffraction. The position parameters of the oxygen atoms in α-Bi2O3 were refined. High temperature neutron diffraction shows that a complicated disorder exists in the oxygen sublattice of the fluorite related structure of the solid electrolyte δ-Bi2O3. X-ray diffraction data on metastable β-Bi2O3 correspond with a distorted fluorites structure with the voids in the oxygen sublattice ordered in the 〈001〉 direction. X-ray and neutron diffraction data indicate that metastable γ-Bi2O3 is isomorphous to Bi12GeO20.
Effect of Solvent Characteristics on the Ultrasonic Degradation of Poly(vinylpyrrolidone) Studied by On‐line Monitoring

Ultrasonic degradation of high molecular weight poly(vinylpyrrolidone) is monitored on-line, by light scattering. Degradations are performed in water/methanol mixtures of various compositions at room temperature. The evolutions of the weight average molecular weight and the radius of gyration are monitored. The dependence of the radius of gyration on the molecular weight is found. The second virial coefficients (A 2 ) of polymer samples in each solvent are found using Zimm plots. These mixtures are found to be close to theta solvents for poly(vinylpyrrolidone). Degradation rate constants and limit molecular weights are correlated with the radii of gyration and A 2 coefficients of the polymer in the solvents studied. It is found that degradation is more effective in better solvents. The dependence of the degradation parameters on solvent characteristics (e.g., the enthalpy of vaporization, solvent viscosity and surface tension) was also investigated and found to be much less significant than for the parameters above.