Miracle-dz/UniFAR-FTUs huggingface dataset:
Adsorption of Hydroxy-Al Polycations and Destabilization of Illite and Montmorillonite Suspensions

Water-infiltration characteristics of soil can be improved by preventing clay dispersion. The present study determined the adsorption properties of hydroxy-Al polycations (Al-p) and their relation to the destabilization of clay suspensions. Al-p was synthesized and fractionated into nominal molecular weights between 104 and 5 × 104. The reactions of Al-p with Na-illite and Na-montmorillonite indicated a very strong affinity of Al-p to the clay surfaces. The maximum adsorptions of Al-p by Na-illite and Na-montmorillonite were found to be 0.37 and 1.7 mmole Al/g, and very close to the cation-exchange capacity of the two clays, suggesting that the adsorption was chiefly controlled by the mechanism of charge screening. Adsorption of Al-p increased the points of zero charge (PZCs) and the apparent points of zero salt effect (PZSEs) of illite and montmorillonite. PZSEs for both clays were 4.7 at their maximum Al-p adsorption, and PZCs ranged from 5.3 to 6.4, depending on solution ionic strength and the individual clay minerals. The differences in PZCs were probably due to outer-sphere complex formation between Al-p-treated illite and montmorillonite and the swamping electrolyte. Critical flocculation concentrations (CFCs) of Al-p for Na-illite and Na-montmorillonite were at 0.28 and 1.0 mmole Al/g, whereas zero electrophoretic mobilities were at about 0.36 and 1.67 mmole Al/g Al-p additions. Excessive addition of Al-p reversed this surface charge of clay colloids and restabilized the illite but not montmorillonite suspensions. This difference was probably due to the stronger and more extensive interparticle bridging of montmorillonite particles by Al-p than those of illite. The CFCs for the two clays were also found to be dependent on sodium adsorption ratio (SAR), pH, and ionic strength. Increases in SAR and pH significantly increased the CFC, whereas an increase in ionic strength decreased the CFC.
Screen-printed carbon electrodes modified with cellobiose dehydrogenase: Amplification factor for catechol vs. reversibility of ferricyanide

A number of screen-printed carbon electrodes (SPCEs) have been electrochemically studied revealing strong correlation between the reversibility of the Fe(CN)/Fe(CN) couple and the sensitivity for catechol at the same electrodes modified with cellobiose dehydrogenase (CDH). Pretreatment of the electrode surfaces increased both the heterogeneous ferricyanide reaction rate and the catechol sensitivity. From cyclic voltammetric and chronoamperometric measurements of Fe(CN) it was concluded that the tested SPCEs behave as microelectrode arrays. Using the pinhole model the fraction of electroactive area was determined to directly correlate to a faster heterogeneous electron transfer for ferricyanide and a higher CDH-modified biosensor sensitivity for catechol. An electroactive area of 50% and higher is sufficient to create a sufficiently good biosensor for catechol. (Less)
Efficient synthesis of carbon nanotubes with improved surface area by low-temperature solvothermal route from dichlorobenzene

The synthesis of well-aggregated carbon nanotubes in the form of bundles was achieved by the catalytic reduction of 1,2-dichlorobenzene by a solvothermal approach. The use of 1,2-dichlorobenzene as a carbon source yielded a comparably good percentage of carbon nanotubes in the range of 60–70 %, at a low reaction temperature of 200°C. The products obtained were analysed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. The X-ray diffraction studies implied the presence of pure, crystalline, and well-ordered carbon nanotubes. The scanning electron and transmission electron microscopic images revealed the surface morphology, dimensions and the bundled form of the tubes. These micrographs showed the presence of multi-walled carbon nanotubes with an outer diameter of 30–55 nm, inner diameter of 15–30 nm, and lengths of several hundreds of nanometers. Brunauer-Emmett-Teller-based N2 gas adsorption studies were performed to determine the surface area and pore volume of the carbon nanotubes. These carbon nanotubes exhibit a better surface area of 385.30 m2 g−1. In addition, the effects of heating temperature, heating time, amount of catalyst and amount of carbon source on the product yield were investigated.
Biological hydrogen production using co-culture versus mono-culture system

In coming years, the generation of organic wastes will exceed 250 billion tonnes worldwide. The organic wastes offer plentiful source of readily available and inexpensive substrates for fermentative hydrogen production. A sustainable approach for hydrogen production from various methods, such as photo-, dark fermentation and sequential two-stage has significant advantages to complement traditional process. During hydrogen fermentation, defined, well-characterized and composite microorganisms are studied. Substantial research efforts have been carried out to increase hydrogen production by using co-culture system, which offers advantage of increased H2 yield and production rate in comparison with mono-culture. The concept of co-culture system is a simple step of mixing different microbial strains for improving the individual properties that other strain lacks. Co-culture system is cost-effective, which potentially eliminates pretreatment step and avoids the use of expensive reducing agent. By eliminating these two steps, the overall process cost can be reduced without negotiating the hydrogen yield. The co-culture system directly hydrolyses complex organic substrates into fermentable sugar with 94.1% improved yield in comparison with mono-culture. Co-culture offers various advantages, example, reduction in lag phase, resistance to environmental fluctuations and provides stability with uninterrupted hydrogen production rate, which is eight times in comparison with mono-culture. The co-culture system of hydrogen production is also an alternative effluent treatment method with 60% reduction in the chemical oxygen demand level and can be easily integrated into a pilot scale to achieve continuous H2 production. The elaboration on co-culture system suggests a huge potential of hydrogen production using complex organic wastes with viable application towards industrialization.
Flow Injection Monitoring of Aflatoxin M1 in Cheese Using Filter‐Supported Bilayer Lipid Membranes with Incorporated DNA

This work describes a technique for the rapid and sensitive electrochemical flow injection monitoring of aflatoxin M1 (AFM1) in cheese samples. Stabilized filter-supported bilayer lipid membranes (BLMs) were used as detectors Single stranded DNA oligomers terminated with alkyl chains (dT20–C16) were incorporated into the membranes to control surface electrostatic properties. The incorporation of dT20–C16 in BLMs lowered the detection limit for the detection of this toxin by one to four orders of magnitude as compared with the detection limit obtained in the absence of DNA. Therefore, it is now possible to continuously monitor this toxin at concentrations that approached those that could be of interest as set by the U.S. Food and Drug Administration and most European countries. The work described herein takes a significant step towards development of a detector of greater practical potential by demonstrating that the incorporation of C16-ssDNA into lipid membranes results in a combination of properties that provides for a much more sensitive and robust detection system. Injections of AFM1 were made into flowing streams of a 0.1 M KCl electrolyte solution, and a transient current signal with duration of seconds reproducibly appeared in about 12 s after exposure of the detector element to the toxin. The magnitude of this signal was linearly related to the concentration of AFM1 with detection limits at subnanomolar level. The effect of interferents such as proteins and lipids was investigated. It was determined that interferences from proteins could be eliminated by adjustment of the flow rate of the carrier electrolyte solution. The technique was applied for the rapid flow injection determination of aflatoxin M1 in cheese samples. AFM1 could be determined in continuous flowing systems with a rate of at least 4 samples min–1. Repetitive cycles of injection of AFM1 have shown no signal degradation during each cycle for experiments that attempted over 30 cycles of detection.
Thermophysiological vulnerability to Heat stress among Indoor workers

Introduction: The present study provides a practical importance to assess the magnitude of thermal stress of workers in indoor environment taking into account the workers physiological responses. Method: The study covered indoor workers iron (N=587years) and ceramics (N=426) in three seasons. Thermal measurements were recorded by Wet Bulb Globe Temperature (WBGT) Monitor. The physiological responses include skin temperature, heart rate and blood pressure. Results: The WBGT index in summer month of ceramic (34.9±2.7°C) was higher than iron foundry works (32±1.7°C). The systolic blood pressures in winter month were higher, as compared to summer months (2mmHg in iron and 11mmHg in ceramic). About 32% of iron and ceramic workers had working heart rate greater than 100 beats/min and 3% beyond 130 beats/min during the working day. The skin temperature (Tsk) profile and weighted skin temperature (Tsk) were significantly higher in summer, followed by post-monsoon and winter months. Discussion: The study assesses the physiological and thermoregulatory responses of workers to heat stress and strain for their exposure to extreme hot environment. The limit of peripheral thermoregulatory adjustability may be considered beneficial and can be taken away from the fury of high heat.
Effective Medium Theory of Diffusion and Chemical Reaction in the Presence of Stationary Sinks

We calculate the effective reaction rate constant k∗ and the effective diffusion constant D∗ for a system of randomly distributed imperfect spherical sinks. Imperfect means in this context that the surface reaction rate is finite. We use an effective medium theory presented in a previous paper (Physica A 166 (1990) 206). An application of our model to steady state fluorescence quenching shows perfect agreement with the experimental data reported by Peak et al. (J. Chem. Phys. 79 (1983) 3328).
Regular Solution Model for Asphaltene Precipitation from Bitumens and Solvents

A regular solution theory liquid-liquid equilibrium model was developed to predict asphaltene precipitation from Western Canadian bitumens. The input parameters for the model are the mole fraction, molar volume, and solubility parameters for each component. Bitumens were divided into four main pseudo-components corresponding to SARA fractions: saturates, aromatics, resins, and asphaltenes. Asphaltenes were divided into fractions of different associated molar mass based on a Schultz-Zimm molar mass distribution. Asphaltene self-association was accounted for through the average molar mass of the distribution. The molar volumes and solubility parameters of the pseudo-components were calculated using solubility, density, and molar mass measurements. The model successfully predicted the effect of solvent type and associated molar mass on asphaltene precipitation for model oil and n-alkane systems. The model also predicted the onset and amount of asphaltene precipitation from bitumens.
Development of New Analytical Method and Its Validation for the Determination of Tramadol Hydrochloride in Bulk and Marketed Formulations

Tramadol hydrochloride in presence of acidic medium reacts with excess amount of Chloramine-T and remaining Chloramine-T react with Crystal violet to produce blue colour. The final stock solution was made to produce 100μg/ml with methanol. The λmax was found to be 591 nm for assay. The linearity was found in concentration range of 5-30μg/ml. The correlation coefficient was found 0.999. The regression equation was found as Y= 0.025X + 0.001. The method was validated according to ICH Guidelines.
(2+2) Photocycloadditions with Chiral Uracil Derivatives: Access to All Four Stereoisomers of 2-Aminocyclobutanecarboxylic Acid

Starting from a single, chiral, bicyclic derivative of uracil, all four stereoisomers of 2-aminocyclobutanecarboxylic acid have been prepared in enantiomerically pure form, using a synthetic sequence which begins with a key photochemical (2+2) cycloaddi- tion reaction and includes a practical cis to trans b-amino acid isom- erisation procedure. The impact of b-amino acids and b-peptides in nature, 1 in medicinal chemistry, 2 and in the controlled design of pep- tide folding structures 3 is evident from the exponential in- crease in the volume of published research on these substances. 4 Commensurately, an increasing variety of methods have been described for the synthesis of b-amino acids in both racemic and enantiomerically enriched form. 5 A particular interest has developed for alicyclic b- amino acids; 6 these compounds are of biological interest in their own right, 6,7 while hybrid or homo-oligomers which contain these rigid cyclic motifs pre-organize in a well-defined manner leading to unique 'foldamer' struc- tures. Thus, stable helical motifs have been prepared using oligomers of trans-2-aminocyclohexanecarboxylic acid 8 and trans-2-aminocyclopentanecarboxylic acid, 8b,9 and some of these oligopeptides are bestowed with biological activities 10 or liquid crystal properties. 11 In marked con- trast, oligomers of cis-2-aminocyclopentanecarboxylic acid adopt a sheet-like structure. 12 Much less work has been done using small-ring b-amino acids, although initial results have been promising: for example, cis-2-aminocy- clopropanecarboxylic acid derived oligopeptides adopt stable helical conformations. 13 In the only studies involv-
Long‐Term Observations of Isotope Ratio Accuracy and Reproducibility Using Quadrupole ICP‐MS

High precision isotope ratio and trace element determination can be achieved with modern quadrupole ICP‐MS provided that short and long‐term instrument performance is accurately monitored. Here we present results for the isotope ratios 6Li/7Li, 147Sm/149Sm, 160Dy/161Dy, 207Pb/206Pb, 208Pb/206Pb, 206Pb/204Pb and 235U/238U with which we determined long‐term isotope ratio stability of relevance to both trace element and isotope determination. With respect to trace element determination, we first present long‐term observations regarding oxide formation rates of Ba and Nd on light REE and heavy REE, as well as Zr on Ag. These showed good correlations and could be used to correct effectively the interference. The efficacy of this correction was demonstrated with analyses of the rock reference material BHVO‐2 at both low and high oxide formation rates. Next, we studied the long‐term reproducibility of a Dy isotope ratio that was measured to correct for the isobaric interference on Gd. It was found that, regardless of tuning condition, the ratio reproduced very well (0.58% RSD, 1s) and that the estimate of the Gd concentration did not suffer from the large correction (> 10%) caused by the Dy isobar. Long‐term reproducibilities of Li, Sm and U isotope ratios, required for accurate mass bias correction when isotopically enriched internal standards of these elements are employed, were measured in the rock reference materials AGV‐2 and JA‐3 over a time period of up to 3 years. As expected, the Li isotope ratio showed the largest variability (RSD = 7%), but the other two ratios had relative external reproducibilities of only 1.01% (1s, U) and 0.67% (Sm). The mass bias‐induced scatter in measurements for Sm and U was so small that the internal standard correction was effective, even for samples with high concentrations of these elements. With regard to Pb‐isotope ratio determination, we also present long‐term reproducibility for NIST SRM 982, run as an unknown and two accuracy tests for Pb separated from granitoids and from meteorites. It is demonstrated that the obtained ratios, including those involving 204Pb, are accurate relative to MC‐ICP‐MS determinations and of comparable precision to conventional TIMS analysis. The excellent agreement between all data sets shows the potential of modern quadrupole ICP‐MS instrumentation for Pb‐isotope determination, particularly for samples with very low Pb content.
Comparison by X-ray Diffraction and Infrared Spectroscopy of Two Samples of α Quartz with the NIST SRM 1878a α Quartz

The aim of this study was to compare the X-ray diffraction and infrared spectrophotometric patterns of two samples of alpha quartz (QUIN1 and QUIN2) with that of NIST SRM 1878a alpha quartz certified 100% crystalline. As it is known that the intensity diffracted and the absorbance per mass unit for a given type of alpha quartz depend on its particle size, this factor was taken into account. To do this, different types of alpha quartz were sampled on filters using a Dorr-Oliver cyclone to select particle size. Variation in the flow rate of the cyclone in the range 1.2-2.8 l/min allowed the volume median diameter of the sampled particles to be varied. For the four strongest diffraction lines it was observed that the intensity per mass unit increased with the volume median diameter of the particles. For infrared spectrophotometry for analytical band wavelengths close to 12.5 micro m, it was observed that the absorbance per mass unit decreased as particle size increased. The opposite effect was noted for analytical band wavelengths >14.4 micro m. Compared with SRM 1878a alpha quartz, certified 100% crystalline, the purity of QUIN1 alpha quartz was 93.1% (confidence interval 92.4-93.8%) when measured by X-ray diffraction and 91.5% (confidence interval 90.1-92.9%) when measured by infrared spectrophotometry. In the case of QUIN2 alpha quartz the purity was globally lower.
Determination of polycyclic aromatic hydrocarbons on SMA-EGDMA polymeric mononlith column by capillary electrochromatography

In this study, a reversed-phase C18 polymeric monolith column of stearyl methacrylate-co-ethylene glycol dimethacrylate (SMA-EGDMA) was prepared and used to separate polycyclic aromatic hydrocarbons (PAHs) by capillary electrochromatography. The prepared column exhibits a good efficiency of 20,000 plates per m for naphthalene. The separation conditions for PAHs were systematically optimized. The optimized condition for the mobile phase was acetonitrile/10 mM ammonium acetate, pH 7 (80/20, v/v), and the applied voltage was set at 28 kV. Subsequently, an on-line concentration was employed to the CEC separation and by changing injection time a dramatic improvement was observed in the detection sensitivity up to 50-fold enhancement, achieving nanogram level with almost no loss of resolution. Six polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, benz[a]anthracene) showed good linearity with linear correlation coefficient R > 0.99. Reproducibility of the column was investigated. Relative standard deviations of migration time (n = 5) and peak area (n = 5) were in the range of 4.71–4.93% and 4.88–6.65%, respectively, for the six polycyclic aromatic hydrocarbons on the SMA-EGDMA polymeric monolith column. The percentage recoveries of six PAHs including naphthalene, fluorene, phenanthrene, fluoranthene, pyrene and benz[a]anthracene in East Lake water samples at three different concentrations are 93.7–102.5, 98.6–108.1, 92.6–105.9, 95.2–102.1, 91.8–105.4, and 100.9–103.7, respectively.
Trading Volume and Volatility in the US Stock Markets

This thesis investigates the relationship between trading volume and stock return volatility using GARCH model in the framework of Mixture of Distribution Hypothesis. Analysis is carried out for five well-known stocks selected from the American S&P500 stock index. Our approach was to extend the variance equation of the well known GARCH model on the trading volume which was split into three explanatory variables capturing different effects of volume on volatility. Apart from the relationship itself, we examined the changes of GARCH and ARCH parameters after the inclusion of volume, implicitly testing the Mixture of Distribution Hypothesis. Interesting results and implications for future research were identified. Firstly, we highlight the appropriateness of the volume decomposition into expected and unexpected volume, where all the volume parameters turned out to be statistically significant. General observation was that the increase of both expected and unexpected trading volume leads to the increase of volatility. On the other hand, negative volume shocks tend to decrease it. Eventhough we performed the analysis with lagged and also contemporaneous volume, we were not able to confirm that the inclusion of volume leads to insignificance of the ARCH and GARCH parameters, thus not confirming the Mixture of Distribution Hypothesis. However, we found that the volume models perform significantly better than the plain GARCH models according to AIC. Considering these findings, it is possible to conclude that there is positive relationship between the stock return volatility and trading volume. We also found that the volume models perform substantially better in modeling and predicting the future volatility. JEL Classification C22, C52, C55, G12
Comparison of methods for the estimation of the thickness of ultrathin tissue sections

For a number of quantitative electron microscopical techniques it is relevant to obtain an estimate of the thickness t‘ of the section which, in general, will differ from the actual distance t between the two cuts that generate the section. To estimate t’ of ultrathin sections, several techniques have been adopted in the past, both with and without the aid of the electron microscope and additional equipment, which are summarized in an appendix. In the present study five methods have been evaluated experimentally using sections of ten different interference colours: (a) the ‘small‐fold’ technique, (b) the ‘electron scattering’ method, (c) interference microscopy with (A) the Vicker's M86® scanning microinterferometer and (B) the Jenoptik Amplival Interphako® interference microscope and (d) the ‘re‐embedding’ method. Reliable, reproducible and comparable results were obtained with the small‐fold technique, with the Vickers M86® scanning microinterferometer and with the electron scattering method. For the last method, standard test lines for the different settings of the electron microscope were developed. The results obtained with the Jenoptik Amplival Interphako® interference microscope are reproducible, but show a constant difference, i.e. a factor of 1 “36, in thickness compared with the other three techniques. The possible cause of this ‘systematic error’ is discussed. The re‐embedding method proved to be more laborious and slightly less reliable than the other techniques.