Accuracy of Numerical Methods in Determination of Residual Stresses Due to Cold Expansion in Metallic Materials

Today more than ever, it was tried to reach the optimum usage of materials by applying various methods of manufacturing processes. Increasing the fatigue life of components is one of important aims. All parts of a machine must be connected together for incoming to service. Nonpermanent connections like bolt and nut joints must have hole on both components. Fatigue life was increased if these holes were reinforced by various methods. One of the ways is producing compressive residual stress in near fields of hole by cold expansion (CE) method. In this study the CE process was applied to plate was made from elastic–perfectly plastic material. Residual stresses distributions were obtained by analytical and numerical methods (using finite elements analysis). Results of these methods were compared together for determination the accuracy of numerical methods. In the next step, residual stress distribution due to the CE in real material (aluminum) was determined numerically. Three numerical methods were used: really simulation method (3D plate with punch), 2D and 3D model with internal pressure (using try and error, the amount of pressure that was needed to introduce the same CE ratio was determined) and finally, 2D and 3D model with radial displacement in internal surface of the hole. It was determined that the first and second methods have good agreement with experimental results so can be used for simulation of the CE process.     

Optimization of biohydrogen production by Clostridium butyricum EB6 from palm oil mill effluent using response surface methodology

Clostridium butyricum EB6 successfully produced hydrogen gas from palm oil mill effluent (POME). In this study, central composite design and response surface methodology were applied to determine the optimum conditions for hydrogen production (P_c) and maximum hydrogen production rate (R_max) from POME. Experimental results showed that the pH, temperature and chemical oxygen demand (COD) of POME affected both the hydrogen production and production rate, both individually and interactively. The optimum conditions for hydrogen production (P_c) were pH 5.69, 36 °C, and 92 g COD/l; with an estimated P_c value of 306 ml H₂/g carbohydrate. The optimum conditions for maximum hydrogen production rate (R_max) were pH 6.52, 41 °C and 60 g COD/l; with an estimated R_max value of 914 ml H₂/h. An overlay study was performed to obtain an overall model optimization. The optimized conditions for the overall model were pH 6.05, 36 °C and 94 g COD/l. The hydrogen content in the biogas produced ranged from 60% to 75%.     

Integration of GIS and multicriteria decision analysis for urban aquaculture development in Bangladesh

Site selection is a key factor in any aquaculture operation, affecting both success and sustainability as well as solving land or water use conflicts. This study was conducted to identify suitable sites for carp farming development in urban water bodies (UWBs) of Chittagong, Bangladesh using Geographical Information Systems (GIS) based MultiCriteria Evaluation (MCE) of water, soil and infrastructure database. ASTER imagery and 14 thematic layers were analyzed with ENVI and GIS capabilities, and developed a series of GIS models to identify and prioritize the appropriate UWBs for carp farming. The study identified 487 UWBs occupying 362 ha and revealed 280 ha (77%) is the most suitable, 36 ha (10%) is moderately suitable and 46 ha (13%) is not suitable which was consistent with field verification. The results are encouraging for extension of carp culture and diversify the economic activities of the urban dwellers.     

Structural and opto-electrical properties of pyrolized ZnO-CdO crystalline thin films

A series of ZnO-CdO thin films of different molar ratios of Zn and Cd have been deposited on glass substrate at substrate temperature ~ 360 ℃ by the spray pyrolysis technique at an ambient atmosphere. X-ray diffraction (XRD) studies confirmed the polycrystalline nature of the film and modulated crystal structures of wurtzite (ZnO) and cubic (CdO) are formed. The evaluated lattice parameters, and crystallite size are consistent with literature. Dislocation density and strain increased in the film as the grain sizes of ZnO and CdO are decreased. The band gap energy varies from 3.20 to 2.21 eV depending on the Zn/Cd ratios in the film. An incident photon intensity dependent I-V study confirmed that the films are highly photosensitive. Current increased with the increase of the intensity of the light beam. The optical conductivity and the optical constants, such as extinction coefficient, refractive index and complex dielectric constants are evaluated from transmittance and reflectance spectra of the films and these parameters are found to be sensitive to photon energy and displayed intermediate optical properties between ZnO and CdO, making it preferable for applications as the buffer and window layers in solar cells.     

The structure and photocatalytic performances of mechanically synthesized poly(3′,4′‐ethylenedioxy‐2,2′:5′,2″‐Terthiophene)/Zno composites

Poly(3′,4′‐ethylenedioxy‐2,2′:5′,2″‐terthiophene)/ZnO(poly(TET)/ZnO) composites with the ratio of poly(TET) and nano‐ZnO from 3:1 to 1:3 were synthesized by hand grinding and ball milling methods, respectively. The photocatalytic activities of the composites were examined through the degradation processes of methylene blue (MB) solution under UV light irradiation, and the possible mechanism for the photocatalytic activity enhancement by synergetic effects between nano‐ZnO and poly(TET) was proposed. The results showed that the strong interactions between the poly(TET) and nano‐ZnO occurred in the case of ball milling method. The results also proved that the crystallinity of ZnO was not disturbed in both of methods, and the nano‐ZnO was uniformly distributed in polymer matrix in the case of ball milling method. The comparative studies showed that the addition of the nano‐ZnO could enhance the photocatalytic activities of the composites. The highest degradation efficiency (100%) at 3 h under UV light irradiation occurred in the case of poly(TET)/ZnO(1:1) synthesized by ball milling method. Furthermore, the nanocompsosite displayed higher photocatalytic activity than nano‐ZnO, which was due to the holes (h⁺) transferring from the valence band of ZnO to the polymer backbone and the adsorption of MB molecules in polymer matrix via π–π conjugation between MB and aromatic regions of the poly(TET). POLYM. COMPOS., 36:1597–1605, 2015. © 2014 Society of Plastics Engineers     

Occurrence of two genotypes of tetracycline (TC) resistance gene tet(M) in the TC-resistant bacteria in marine sediments of Japan

The tetracycline (TC) resistance gene tet(M) was monitored in bacteria isolated from Japanese coastal and off-shore marine sediments. The high rate of occurrence of TC resistant (TC(r)) bacteria (120 microg mL(-1) TC) was observed at frequency ranges between 0.0-0.08% in Tokyo Bay, 1.67-1.82% in Sagami Bay and 0.0-4.35% in the open Pacific Ocean. The tet(M) gene was PCR amplified from the TC(r) isolates, showing 127 of 209 isolates (60.8%) as positive. The rate of occurrence of tet(M) was between 32.0-96.0%, 21.1 -28.0% and 0.0-83.3% in the isolates from Tokyo Bay, Sagami Bay and the open Pacific Ocean, respectively. The tet(M) positive isolates belonged to 4 orders of bacteria. Bacillales was the most dominant order (121 strains) among tet(M) possessing bacteria, followed by Actinomycetales (three strains), Flavobacteriales (one strain) and Pseudomonadales (one strain). This indicates that tet(M) is present in various bacterial species and suggests that marine sediments are a natural reservoir of the tet(M) gene. Nucleotide sequence of the tet(M) revealed that two genotypes of tet(M) were found in the bacteria. The two genotypes were placed in genetically distant branches of the phylogenetic tree, suggesting that the two tet(M)s have different origins.     

Mass balance of total mercury and monomethylmercury in coastal embayments of a volcanic island: significance of submarine groundwater discharge

To understand the contribution of submarine groundwater discharge (SGD) to the coastal mass budgets of Hg and monomethylmercury (MMHg), preliminary mass balance estimates were made for Hwasun and Bangdu Bays on Jeju Island, known to have large SGD due to the high permeability of the volcanic rocks. The mass balance results indicate that SGD is a main source of Hg in Hwasun Bay (23 ± 14 × 10(-2) mol yr(-1), 34%) and Bangdu Bay (23 ± 20 × 10(-2) mol yr(-1), 67%), although the contribution from atmospheric deposition was considerable (25% for Hwasun and 23% for Bangdu). MMHg was also discharged primarily from submarine groundwater at Hwasun (0.30 ± 0.17 × 10(-2) mol yr(-1), 55%) and Bangdu (0.65 ± 0.49 × 10(-2) mol yr(-1), 64%), which was higher than atmospheric deposition (6% for Hwasun and 2% for Bangdu) and sediment diffusion flux (5% for Hwasun and 3% for Bangdu). The overall mass balance results suggest that, although there are large spatial variations in SGD rates throughout the region, the coastal mass budgets of Hg and MMHg need to include SGD as well as atmospheric deposition and sediment diffusion as primary sources of Hg and MMHg.     

Effect of processing on the composition and oxidative stability of coconut oil

The effect of various processing procedures on the composition and oxidative stability of coconut oil has been studied. The crude oil is relatively stable but major reductions in oxidative stability occur during the bleaching of oil degummed with phosphoric acid; during alkali refining; during the deodorization of oil degummed with citric acid and bleached; and during the deodorization of oil processed with a combined phosphoric acid degumming and bleaching operation. The reasons for the loss of oxidative stability during processing are discussed with reference to changes in the composition of the oil. Residual traces of citric acid or phosphoric acid play an important role in stabilizing processed oils. The tocopherol content is also important, although no additional stabilization of the oil occurs on adding levels of tocopherol above those present naturally in the crude oil. A combined phosphoric acid degumming and bleaching process leads to smaller losses of tocopherols than sequential treatments.     

The effect of magnetic and optic field in water electrolysis

Hydrogen production via water electrolysis was studied under the effect of magnetic and optical field. A diode solid state laser at blue, green and red were utilized as optical field source. Magnetic bar was employed as external magnetic field. The green laser has shown a greatest effect in hydrogen production due to its non-absorbance properties in the water. Thus its intensity of electrical field is high enough to dissociation of hydronium and hydroxide ions during orientation toward polarization of water. The potential to break the autoprotolysis and generate the auto-ionization is the mechanism of optical field to reveal the hydrogen production in water electrolysis. The magnetic field effect is more dominant to enhance the hydrogen production. The diamagnetic property of water has repelled the present of magnetic in water. Consequently the water splitting occurs due to the repulsive force induced by the external magnetic field. The magnetic distributed more homogenous in the water to involve more density of water molecule. As a result hydrogen production due to magnetic field is higher in comparison to optical field. However the combination both fields have generated superior effect whereby the hydrogen yields nine times higher in comparison to conventional water electrolysis.     

Molecular Pathogenesis of Glioblastoma in Adults and Future Perspectives: A Systematic Review

Glioblastoma (GBM) is the most common and malignant tumour of the central nervous system. Recent appreciation of the heterogeneity amongst these tumours not only changed the WHO classification approach, but also created the need for developing novel and personalised therapies. This systematic review aims to highlight recent advancements in understanding the molecular pathogenesis of the GBM and discuss related novel treatment targets. A systematic search of the literature in the PubMed library was performed following the PRISMA guidelines for molecular pathogenesis and therapeutic advances. Original and meta-analyses studies from the last ten years were reviewed using pre-determined search terms. The results included articles relevant to GBM development focusing on the aberrancy in cell signaling pathways and intracellular events. Theragnostic targets and vaccination to treat GBM were also explored. The molecular pathophysiology of GBM is complex. Our systematic review suggests targeting therapy at the stemness, p53 mediated pathways and immune modulation. Exciting novel immune therapy involving dendritic cell vaccines, B-cell vaccines and viral vectors may be the future of treating GBM.