Studies on artificial coal. 2. Thermogravimetry, plastometry and differential thermal analysis

The artificial coals (AC) or coal models were prepared from sawdust, lignite and cork by the method of hydrothermal carbonification. The specific techniques used to study their pyrolytic behaviour were thermogravimetry, Gieseler plastometry and differential thermal analysis (DTA). The principal conclusions drawn are:

1. (1) The initial stage of pyrolysis of AC can be considered to be governed by an overall reaction of first order, as in the case of natural coals.

2. (2) All caking types of AC showed quite low softening points (75–210 °C), the values for sawdust AC being lower than those for the cork AC. The latter showed fairly sharp peak values of the temperature of maximum fluidity, but the sawdust AC showed only a range of temperatures of maximum fluidity, the upper limit being less than the maximum fluidity temperature of the cork AC. However the temperatures of resolidification were consistently high, namely 425 °C and above, thus bringing in a significant point of similarity with natural caking coals.

3. (3) The value of maximum fluidity was very high for one AC sample, exceeding 27000 dial div./min. Such a high value is rare for natural caking coals. With the latter, no correlation could be observed between the caking properties and maximum fluidity. Hence the role played by the stability of the plastic mass may be the more dominant factor in the caking process.

4. (4) From the comparison of the softening temperatures and the temperatures of active decomposition of the AC, it is inferred that the process of initial softening of coal may be physical in nature.

5. (5) The AC indicated an overwhelming exothermicity in their primary pyrolysis, thus behaving like the natural coals studied under similar experimental conditions.

     

Effect of abrasive contaminants on scuffing

Four-ball machine tests have been performed to study the effect on scuffing of fine silica abrasive particles contained in the lubricant. The boundary lubrication zone that sets in after seizure recovery has been utilized in the study. The particles are found to increase abrasive wear but reduce adhesive wear and to cause scuffing at less severe conditions that with clean oil by contributing to frictional heating. When the heat generated cannot be dissipated from the contact zone the contact temperature is found to increase and lubricant desorption causes scuffing.     

Copolymerization of poly(1‐naphthylamine) with aniline and o‐toluidine

The commercial use of polyaniline has been impeded by its intractable nature and insolubility. The use of substituted polyaniline has been attempted mainly to increase the processibility of polyaniline, but this approach usually results in the lowering of the conductivity. This study reports the synthesis of poly(1‐naphthylamine), a fused ring derivative of polyaniline, and its copolymers with aniline and o‐toluidine via a chemical polymerization method. Spectral, thermal, morphological, and conductivity studies were carried out to elucidate the influence of the incorporation of aniline and o‐toluidine units into poly(1‐naphthylamine). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microencapsulation of Tender Coconut Water by Spray Drying: Effect of <Emphasis Type="Italic">Moringa oleifera</Emphasis> Gum,Maltodextrin Concentrations,and Inlet Temperature on Powder Qualities

The present study was aimed to evaluate the different proportions of carrier materials: Moringa oleifera gum (MG), maltodextrin (MD), and inlet temperature on the powder characteristics of encapsulated tender coconut water (TCW) by spray drying. The characterization of microparticle was studied as encapsulation efficiency, antioxidant activity, total phenolic content, moisture content, water activity, solubility, particle morphology, and encapsulation yield. The investigation was conducted using an experimental design of 2² mixes with five replicates at the center point. The encapsulation efficiency was affected by all tested variables and reached significantly (p < 0.05) higher value (94.86%) when higher MG concentration, and lower MD concentration, and inlet temperature were applied. The DPPH (53.66%) and ABTS radical scavenging activity (54.92%) was observed to be higher at the highest MG concentration (1.5%). The obtained powder retained a higher amount of phenol content (21.82 mg GAE/g) at increasing MG concentration, with decreasing MD concentration, and inlet temperature. X-ray diffraction (XRD) analysis revealed that TCW powder encapsulated with 1.5% MG exhibited higher crystalline nature as compared to microparticle encapsulated with 0.5 and 1% MG. The optimum wall material composition and inlet temperature were determined as follows: MD 30%, MG 1.5%, and 120 °C inlet temperature. Hence, our results suggest that the application of this technology could increase the use of TCW in various industrial applications and imply MG as a potent candidate for microencapsulation of food materials.     

Adhesion inhibition of F1C-fimbriated Escherichia coli and Pseudomonas aeruginosa PAK and PAO by multivalent carbohydrate ligands

In order to evaluate their inhibition of bacterial adhesion, the carbohydrate sequences GalNAcbeta1-->4Gal and GalNAcbeta1-->4Galbeta1-->4Glc were synthesized. The disaccharide was conjugated to dendrons based on the 3,5-di-(2-aminoethoxy)-benzoic acid branching unit to yield di- and tetravalent versions of these compounds. A divalent compound was also prepared that had significantly longer spacer arms. Relevant monovalent compounds were prepared for comparison. Their anti-adhesion properties against F1C-fimbriated uropathogenic Escherichia coli were evaluated in an ELISA-type assay by using a recombinant strain and also by using Pseudomonas aeruginosa strains PAO and PAK. Adhesion inhibition was observed in all cases, and multivalency effects of up to one order of magnitude were observed. The combination of spacer and multivalency effects led to a 38-fold increase in the potency of a divalent inhibitor with long spacer arms towards the PAO strain when compared with the free carbohydrate.     

Speciation and Electronic Structure of La<Subscript>1−x</Subscript>Sr<Subscript>x</Subscript>CoO<Subscript>3−δ</Subscript> During Oxygen Electrolysis

Cobalt-containing perovskite oxides are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, a lack of fundamental understanding of oxide surfaces impedes rational catalyst design for improved activity and stability. We couple electrochemical studies of epitaxial La_1?xSr_xCoO_3?δ films with in situ and operando ambient pressure X-ray photoelectron spectroscopy to investigate the surface stoichiometry, adsorbates, and electronic structure. In situ investigations spanning electrode compositions in a humid environment indicate that hydroxyl and carbonate affinity increase with Sr content, leading to an increase in binding energy of metal core levels and the valence band edge from the formation of a surface dipole. The maximum in hydroxylation at 40% Sr is commensurate with the highest OER activity, where activity scales with greater hole carrier concentration and mobility. Operando measurements of the 20% Sr-doped oxide in alkaline electrolyte indicate that the surface stoichiometry remains constant during OER, supporting the idea that the oxide electrocatalyst is stable and behaves as a metal, with the voltage drop confined to the electrolyte. Furthermore, hydroxyl and carbonate species are present on the electrode surface even under oxidizing conditions, and may impact the availability of active sites or the binding strength of adsorbed intermediates via adsorbate–adsorbate interactions. For covalent oxides with facile charge transfer kinetics, the accumulation of hydroxyl species with oxidative potentials suggests the rate of reaction could be limited by proton transfer kinetics. This operando insight will help guide modeling of self-consistent oxide electrocatalysts, and highlights the potential importance of carbonates in oxygen electrocatalysis.     

Recommended Practices and Benchmark Activity for Hydrogen and Oxygen Electrocatalysis in Water Splitting and Fuel Cells

Electrochemical energy storage by making H₂ an energy carrier from water splitting relies on four elementary reactions, i.e., the hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). Herein, the central objective is to recommend systematic protocols for activity measurements of these four reactions and benchmark activities for comparison, which is critical to facilitate the research and development of catalysts with high activity and stability. Details for the electrochemical cell setup, measurements, and data analysis used to quantify the kinetics of the HER, HOR, OER, and ORR in acidic and basic solutions are provided, and examples of state‐of‐the‐art specific and mass activity of catalysts to date are given. First, the experimental setup is discussed to provide common guidelines for these reactions, including the cell design, reference electrode selection, counter electrode concerns, and working electrode preparation. Second, experimental protocols, including data collection and processing such as ohmic‐ and background‐correction and catalyst surface area estimation, and practice for testing and comparing different classes of catalysts are recommended. Lastly, the specific and mass activity activities of some state‐of‐the‐art catalysts are benchmarked to facilitate the comparison of catalyst activity for these four reactions across different laboratories.     

VEDSDA: Voronoi Encryption and Decryption for Secure Data Aggregation in WSNs

Wireless Personal Communications - The various application in Wireless Sensor Networks fascinated towards minimal and secure data transmission. In this paper, VEDSDA protocol is proposed to achieve...     

Semi-supervised Weighted Ternary Decision Structure for Multi-category Classification

Neural Processing Letters - Semi-supervised learning has attracted researchers due to its advantages over supervised learning. In this paper, an extremely fast multi-category classification...