Influence of accelerated curing on the compressive strength of polymer-modified concrete

In recent building practice, rapid construction is one of the principal requisites. Furthermore, in designing concrete structures, compressive strength is the most significant of all parameters. While 3-d and 7-d compressive strength reflects the strengths at early phases, the ultimate strength is paramount. An effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate (EVA) at the later phases. Kolmogorov-Smirnov (KS) goodness-of-fit test was used to examine distribution of the data. The compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28, 56, 90, 120, 210, and 365 d. An accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression fit. Based on the results of KS goodness-of-fit test, it was concluded that KS test statistics value (D) in each case was lower than the critical value 0.521 for a significance level of 0.05, which demonstrated that the data was normally distributed. Based on the results of compressive strength test, it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16% concentration. Furthermore, it was concluded that predicted compressive strength values lies within a 6% difference from the actual strength values for all the mixes, which indicates the practicability of the regression equations. This research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.     

Fair‐Weather Friends: Evidence of Lipoxin Dysregulation in Neurodegeneration

Lipoxins (LXs) are autacoids, specialized proresolving lipid mediators (SPMs) acting locally in a paracrine or autocrine fashion. They belong to a complex superfamily of dietary small polyunsaturated fatty acid (PUFA)–metabolites, which direct potent cellular responses to resolve inflammation and restore tissue homeostasis. Together, these SPM activities have been intensely studied in systemic inflammation and acute injury or infection, but less is known about LX signaling and activities in the central nervous system. LXs are derived from arachidonic acid, an omega‐6 PUFA. In addition to well‐established roles in systemic inflammation resolution, they have increasingly become implicated in regulating neuroinflammatory and neurodegenerative processes. In particular, chronic inflammation plays a central role in Alzheimer's disease (AD) etiology, and dysregulated LX production and activities have been reported in a variety of AD rodent models and clinical tissue samples, yet with complex and sometimes conflicting results. In addition, reduced LX production following retinal injury has been reported recently by the authors, and an intriguing direct neuronal activity promoting survival and homeostasis in retinal and cortical neurons is demonstrated. Here, the authors review and clarify this growing literature and suggest new research directions to further elaborate the role of lipoxins in neurodegeneration.     

Pharmacotherapeutics and molecular docking studies of alpha-synuclein modulators as promising therapeutics for Parkinson’s disease

Parkinson’s disease (PD) is an age-related neurodegenerative ailment that affects dopamine-producing neurons in a specific area of the brain called the substantia nigra of the ventral midbrain. It is clinically characterized by movement disorder and marked with unusual synaptic protein alpha-synuclein accumulation in the brain. To date, only a few Food and Drug Administration (FDA) approved drugs are available on the market for the treatment of PD. Nonetheless, these drugs show parasympathomimetic related adverse events and remarkably higher toxicity; hence, it is important to find more efficacious molecules to treat PD. In our study, We chosen 22 natural compounds as inhibitors that potentially block the alpha-synuclein clump—the pathological hallmark of PD—and provide new avenues for its treatment. Most of these molecules exhibited good pharmacokinetic behaviors, making them decisively favorable drug candidates to cure PD. Molecular docking studies were performed to investigate the binding interactions between natural compounds and alpha-synuclein as anti-Parkinson drug targets. Among the examined compounds, curcumin and piperine emerged as promising phytochemicals with the highest binding affinity, key residual stable bindings and showed a good inhibitory features. Thus, the present study indicates that curcumin and piperine hold the potential to be developed as treatment options against PD. Experimental validations are needed for insights into their mechanism of action and potential clinical application.     

Cu-K/Al2O3 based catalysts for conversion of carbon dioxide to methane and carbon monoxide

Abstract

A series of Cu-K/Al₂O₃ catalysts were synthesized by wet impregnation technique. The reduced catalysts were further used for conversion of carbon dioxide to methane and carbon monoxide. Moreover, the fresh and used catalysts were characterized to investigate the changes in the surface morphology, metal dispersion, surface area, crystalline phases, and functional groups of studied catalysts. The SEM analysis of fresh and spent catalysts showed no remarkable difference in surface morphology with irregular shaped agglomerated particles. Furthermore, TEM micrographs presented the well distribution of metal catalyst over alumina support. The decrease in surface area from 115 to 77?m²/g for Cu_1.62-K_0.5/Al₂O₃ after reaction was related to sintering and oxidation of catalyst during reaction. XRD revealed the disappearance of some minor peaks which can be associated with the sintering of spent catalyst. FTIR also presented some new peak for spent catalyst which can be linked with metal oxides. Moreover, various reaction conditions of temperature (230, 400, and 600?°C), pressure (1 and 7?bar), and feed molar ratio of H₂/CO₂ (2:1 and 4:1) were investigated using different Cu loading (0, 1, 1.25, 1.62, and 4 weight percent). A maximum CO₂ conversion of 63% with 39% CH₄ selectivity was achieved by using Cu_1.62-K_0.5/Al₂O₃ at 600?°C, molar ratio of H₂/CO₂ 4 under 7?bar. The presence of K on the surface of synthesized catalyst increased the CO₂ conversion from 48% (Cu₁/Al₂O₃) to 55% (Cu₁-K_0.5/Al₂O₃) at above mentioned reaction conditions which suggested the promoter effect of K during conversion of carbon dioxide.     

On the prediction of the roundness error in BTA deep hole machining based on the stochastic description of the cutting tool motion

This paper presents a methodology of predicting the maximum possible out-of-roundness of the hole produced, in BTA deep hole machining, as a function of certain machining parameters. Based on the solutions of the stochastic differential equations representing the machine tool-workpiece system in BTA deep hole machining, and the true cutting tool motion, an index describing the upper bound of the roundness error is defined. A parametric analysis of the out-of-roundness index is carried out. This analysis points out that at a low length-to-diameter ratio of the cutting tool, the axial force is the predominant factor causing the tool-tip deviation from the ideal motion, and that the radial and tangential forces are the major causes for the tool tip deviation at high length-to-diameter ratio of the cutting tool. The experimental measurement of out-of-roundness of the specimens under different machining conditions shows that the roundness error obtained lies within the zone described by the theoretical prediction.     

An evaluation of Landsat Thematic Mapper (TM) digital data for discriminating coral reef zonation: Heron Reef (GBR)

Coral reefs exhibit patterns of zonation. In this study we have evaluated the usefulness of Landsat-TM digital data as a tool for discrimination and mapping of reef zones. Classification, on bands 1, 2 and 3, and grouping of classes into reef zones was carried out with the aid of canonical variate analysis and minimum spanning trees. Thirteen reef zones can be identified and mapped, at a spatial scale relevant to their dimensions, with confidence. These zones can be further subdivided and mapped as spatially coherent subzones, in order to provide detailed information regarding the density of coral cover on the reef flat. In addition, the canonical variate analysis provides the basis for the aggregation of classes into sub-zones on interpreted primary productivity gradients, which is of relevance to coral reef management, monitoring and research.     

Elastic buckling strength of corroded steel plates

Corrosion makes structures more vulnerable to buckling and yielding failures. It is common practice to assume a uniform thickness reduction for general corrosion. To estimate the remaining strength of corroded structures, typically a much higher level of accuracy is required, since the actual corroded structures have irregular surfaces. Elastic buckling of simply supported rectangular corroded plates are studied with one- and both-sided irregular surfaces. Eigenvalue analysis by using finite element method (FEM) is employed for computing Euler stress. The influence of various geometric and corrosion characteristics are investigated and it is found that the aspect ratio of the plate, the average thickness diminution, the standard deviation of thickness diminution and the amount of corrosion loss have influence on the reduction of buckling strength of the corroded plates. Buckling strength of one- and both-sided corroded plates are the same. In plates with low value of aspect ratio, reduction of buckling strength is negligible. Reduction of buckling strength is more prominent in plates with higher aspect ratio. Reduction of buckling strength is very sensitive to the amount of corrosion loss; the higher the amount of corrosion loss, the more reduction of buckling strength. Reduction of buckling strength is less sensitive to the standard deviation of thickness diminution.     

Effect of Gas Atmosphere Packaging on Psychrotrophic Growth and Succession on Steak Surfaces

The influence of gas atmosphere packaging (1) 15% CO₂, 40% 0₂, 45% N₂; (2) 60% CO₂ 40% 0₂ (3) 10% CO₂, 5% 0₂, 85% N₂; (4) film overwrap (control) on the microbial growth and succession on steaks was studied during storage. Treatment 3 was most effective in reducing psychrotrophic growth on steaks. Pseudomonas species dominated the microflora for all packaging treatments during early storage. In all gas atmospheres. Serratia liquefaciens increased with storage time and the 10% CO₂ atmosphere showed the greatest increase. Enterobacter aerogenes appeared late in the storage period in all atmospheres and Yersinia enterocolitica was isolated after 12 days of storage from steaks in atmosphere 1.     

Development of Unconventional Fabric from Banana (Musa Acuminata) Fibre for Industrial Uses

ABSTRACT

Banana fiber is a lingo-cellulosic under-exploited bast fiber, which obtained from the pseudo-stem of banana plant (Musa acuminata). In this study, an attempt has been made to explore the possibility of production of needle-punched nonwoven from fibrous material of biowaste for value addition and diversified uses. Mechanical processing for preparation of all banana, banana-jute (1:1), and banana-polypropylene (1:1) blended needle punched nonwoven has been optimized and processing parameters have been suggested. Softening treatment of banana fibre has been done successfully for better processing. Boiling in water with 1% nonionic detergent has been suggested as pre-processing for softening. Tenacity, elongation-at-break, initial modulus, breaking energy, stress relaxation, creep, compressibility, recovery-from-compression, bending load, electrical insulation, thermal insulation, sound insulation, air permeability, and frictional force have been evaluated and analyzed for all the above-mentioned samples. Based on those properties the probable use has been suggested as insulation (thermal and sound) and filter material.