Modified bentonites as adsorbents of hydrogen sulfide gases

Carbonate-rich bentonite was modified by iron and copper chlorides in order to synthesize effective and cheap adsorbents for neutralization of H₂S in low-concentrated exhaust gases. Bentonite and modified bentonite were analysed using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and BET surface area analysis. In addition, bentonite and modified bentonite were tested as hydrogen sulfide adsorbents. Iron-containing material showed a significant improvement in the capacity for H₂S removal. The longest time of effective protective action (before H₂S appears on the outlet of the column) was obtained for the bentonite modified with copper hydroxide. The results indicated that on the surface of modified samples hydrogen sulfide reacts with metal hydroxide forming sulfides. Sulfided iron-containing sample could be regenerated by exposing it to the air.     

XPS Structural Studies of Nano-composite Non-platinum Electrocatalysts for Polymer Electrolyte Fuel Cells

The chemical structure of non-platinum electrocatalysts obtained from cobalt porphyrins (CoTMPP or CoTPP) by pyrolysis is investigated by X-ray Photoelectron Spectroscopy (XPS). The catalysts represent highly dispersed, self-supported nano-composites that demonstrate electrocatalytic performance for oxygen reduction and practically no activity in methanol electro-oxidation. High-resolution Co2p, C1s, N1s and O1s XPS spectra acquired from precursors and electrocatalysts pyrolyzed at various experimental conditions were curve-fit using (a) individual peaks of constrained width and shape as well as (b) experimentally obtained photopeaks from the precursor with additional peaks required for a complete curve fit. Principal Component Analysis (PCA) applied to quantitative results from the curve-fits of both types of spectra facilitates visualization and identification of the chemical species that are formed or destroyed, and simplifies evaluation of critical correlations. As a result of these studies it is established that the catalyst is a nano-composite of highly dispersed pyropolymer with some remaining N _x -centers inserted into a graphite-like matrix. Approximately 50% of the metal is distributed as Co²⁺, associated with N₄-centers. The remaining cobalt is present in crystallites of metallic Co. A thin layer of CoO coats these metallic cobalt phases. The developed methodology, described herein, combines model curve-fits and principal component analysis (PCA), resulting in a quantitative and unambiguous understanding of the chemical composition and structure of complex electrocatalysts.     

Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by activated carbon adsorption

Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N2 and air plasmas treatments, O2 plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma discharge zone, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.     

Growth of phthalocyanine doped and undoped nanotubes using mild synthesis conditions for development of novel oxygen reduction catalysts

Precious metal alloys have been the predominant electrocatalyst used for oxygen reduction in fuel cells since the 1960s. Although performance of these catalysts is high, they do have drawbacks. The two main problems with precious metal alloys are catalyst passivation and cost. This is why new novel catalysts are being developed and employed for oxygen reduction. This paper details the low temperature solvothermal synthesis and characterization of carbon nanotubes that have been doped with both iron and cobalt centered phthalocyanine. The synthesis is a novel low-temperature, supercritical solvent synthesis that reduces halocarbons to form a metal chloride byproduct and carbon nanotubes. Perchlorinated phthalocyanine was added to the nanotube synthesis to incorporate the phthalocyanine structure into the graphene sheets of the nanotubes to produce doped nanotubes that have the catalytic oxygen reduction capabilities of the metallo-phthalocyanine and the advantageous material qualities of carbon nanotubes. The cobalt phthalocyanine doped carbon nanotubes showed a half wave oxygen reduction potential of -0.050 ± 0.005 V vs Hg\HgO, in comparison to platinum's half wave oxygen reduction potential of -0.197 ± 0.002 V vs Hg\HgO.     

Can alexithymia be assessed in adolescents? Psychometric properties of the 20-item Toronto Alexithymia Scale in younger, middle, and older adolescents.

The 20-item Toronto Alexithymia Scale (TAS-20; Bagby, Parker, & Taylor, 1994; Bagby, Taylor, & Parker, 1994) is the most widely used self-report measure of the alexithymia construct. The TAS-20 comprises 3 factors that assess difficulty identifying feelings, difficulty describing feelings, and externally oriented thinking. Although the instrument is being increasingly used with adolescent respondents, the psychometric properties of the TAS-20 have not been systematically evaluated in preadult populations. In the present study, we examined measurement invariance of the factor structure, internal reliability, and mean levels of responses on the TAS-20 in groups of younger adolescents (aged 13–14 years), middle adolescents (aged 15–16 years), and older adolescents (aged 17–18 years), as well as in a comparison group of young adults (aged 19–21 years). Formal readability analysis of the TAS-20 assessment was also conducted. Results revealed systematic age differences in the factor structure and psychometric properties of the TAS-20, with the quality of measurement progressively deteriorating with younger age. Much of this effect could be attributed to the reading difficulty of the scale. The use of the TAS-20 with teenage respondents is not recommended without appropriate adaptation and further psychometric validation. Several adaptation strategies are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulation of tumor-specific immunity using tumor cell plasma membrane antigen

An improved methodology is described for the separation of yolk IgG into subpopulations using immobilized metal ion (Fe3+) affinity chromatography. The yolk IgG was first extracted using a prechilled, pre-acidified method. After extraction, the yolk IgG was then fractionated using an Fe3+ column. Using an ascending pH gradient, four IgG containing peaks were well resolved based upon the elution pH, specific activity and the relative avidity index.     

Automatic ectopic beat elimination in short-term heart rate variability measurement

Our studies deal with fully automatic measurement of heart rate variability (HRV) in short term electrocardiograms. Presently, all existing HRV analysis programs require user intervention for ectopic beat identification, especially of supraventricular ectopic beats (SVE). This makes the HRV measurement in large, e.g. epidemiological studies problematic. In this paper, we present a fully automatic algorithm for the discrimination of the ventricular (VE) and SVE ectopic beats from the normal QRS complexes suited for a reliable HRV analysis. The QRS identification is based on the template matching method. The ectopic beats are identified based on several morphological and timing properties of the electrocardiogram (ECG) signal. The method incorporates several approaches and makes HRV analysis of large numbers of electrocardiograms feasible. It uses the template matching for the basic morphology check of the QRS complex and the P-wave, the timing information to avoid unnecessary ectopic beat checks and to adjust thresholds and it also looks for a special QRS morphology, which is common in VEs. We used a testing set of 69 electrocardiograms selected from a large number of recordings. The selected ECGs contained abnormalities including ectopic beats, right branch bundle block, respiratory arrhythmia, blocked atrial extrasystole, high amplitude and wide T-waves. The evaluation of our method showed a specificity of 0.99, supraventricular ectopic beat sensitivity of 0.99 and ventricular ectopic beat sensitivity of 0.98.     

Numerical Analysis of Hydrogen Sulphide Conversion to Hydrogen during Its Pyrolysis and Partial Oxidation

Production of hydrogen during pyrolysis and partial oxidation of hydrogen sulphide is analyzed on the basis of a detailed kinetic model of H₂S oxidation. It is shown that the H₂ yield in the case of H₂S pyrolysis in an adiabatic flow reactor with a residence time of ≈1 s is rather small. Even for the initial temperature of the mixture T₀ = 1400 K, the molar fraction of H₂ is only 12%, though the equilibrium value is reached within the reactor in this case. At T₀< 1200 K, there is no enough time for the chemical equilibrium inside the reactor to be established, and the H₂ concentration is lower than the equilibrium value. At T₀ < 1000 K, the pyrolysis reaction in the reactor practically does not occur. Addition of a small amount of air to H₂S leads to energy release, to an increase in temperature, and, as a consequence, to acceleration of H₂S conversion. The relative yield of H₂ can be increased by several times. For each value of T₀, there exists an optimal value of the fuel-to-air equivalence ratio φ that ensures the maximum H₂ yield in the H₂S–air mixture. The process of partial oxidation at high values of φ > φb and low values of T₀ is essentially nonequilibrium; as a result, the H₂ concentration at the exit from a finite-length reactor can be higher than its equilibrium value, e.g., the relative yield of H₂ can exceed the equilibrium value by 30–40% at T₀ = 800 K and φ = 6–10. The reasons responsible for reaching a “superequilibrium” concentration of H₂ at the flow reactor exit are determined.     

Formation of nanocrystalline and amorphous carbon by high fluence swift heavy ion irradiation of a plasma polymerized polyterpenol thin film precursor

This study aimed to produce graphitic‐polymer nanocomposite thin films via the swift heavy ion irradiation of polyterpenol thin films synthesized from an environmentally sustainable precursor by radio‐frequency plasma enhanced chemical vapor deposition. Atomic force microscopy and scanning electron microscopy revealed fluence‐dependent surface restructuring of the thin films leading to the formation of interconnected island structures, with no discernible delamination from the underlying aluminum substrate. Raman spectroscopy confirmed the development of D and G peaks associated with graphitic materials, whilst Fourier transform infrared spectroscopy indicated retention of the plasma polymer's chemical functionalities (including hydroxyl groups) within the material after irradiation. Graphitic‐polymer nanocomposite films prepared by this dry and solvent‐free process have numerous potential applications in biological assay, organic electronics, and membrane technology. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46498.     

Interfacial phase formation of Al-Cu bimetal by solid-liquid casting method

The solid-liquid method was used to prepare the continuous casting of copper cladding aluminium by liquid aluminum alloy and solid copper, and the interfacial phase formation of Al-Cu bimetal at different pouring temperatures (700, 750, 800 ℃) was investigated by means of metallograph, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods. The results showed that the pouring temperature of aluminum melt had an important influence on the element diffusion of Cu from the solid Cu to Al alloy melt and the reactions between Al and Cu, as well as the morphology of the Al-Cu interface. When the pouring temperature was 800 oC, there were abundant Al-Cu intermetallic compounds (IMCs) near the interface. However, a lower pouring temperature (700 ℃) resulted in the formation of cavities which was detrimental to the bonding and mechanical properties. Under the conditions in this study, the good metallurgical bonding of Al-Cu was achieved at a pouring temperature of 750 ℃.