Synthesis and characterization of nanocomposite NiFe2O4@SalenSi and its application in efficient removal of Ni(II) from aqueous solution

In this work, nano ferrite spinel NiFe2O4 was synthesized by sol-gel method and characterized by SEM, XRD, FT-IR, and VSM. In second step Schiff base made from salicylaldehyde and amino propyl triethoxy silane was used for modification of the synthesized nano ferrit. In the third step removal of Ni(II) was done using modified adsorbent and 95% efficiency was achieved. The removal rate was determined by atomic absorption spectroscopy. These studies showed that the Freundlich isotherm model was fitted well with adsorption data. Moreover, the pseudo-second order kinetic model was fitted very well with experimental data. The results demonstrated that NiFe2O4@SalenSi nanoadsorbent can be used for the removal and recovery of metal ions from wastewater over a number of cycles, indicating its suitability for the design of a continuous process.               KEY WORDS: Nano ferrite, Sol-gel method, Schiff base, Removal of Ni(II), Magnetic nanocomposite Bull. Chem. Soc. Ethiop. 2018, 32(1), 77-88DOI: https://dx.doi.org/10.4314/bcse.v32i1.

Synthesis and crystallographic characterization of new heterotrinuclear oxo-centered complex

New oxo-centered trinuclear mixed-metal complex, of [Fe2ZnO(CHCl2CO2)6(CHCl2CO2)3].NO3 was synthesized by the direct reaction between metal nitrates and dichloroacetic acid. These compounds have a typical μ3-oxo trinuclear structure: (a) three metal atoms are situated in the apexes of the equilateral triangle; (b) μ3-oxygen atom and six dichloroacetate ligands fulfil the bridge functions and (c) the monodentate CHCl2CO2 ligands complete the octahedral geometry of the metal ions. This complex were characterized by elemental analyses (CHN), atomic absorption spectroscopy and spectral (IR, electronic) studies. This is new types of oxo-bridged mixed-metal complex in which the carboxylate ligand is dichloroacetic acid. The UV spectra of the complex exhibited strong bands in the region 213 and 257 nm which are related to the (π → π*) and (n → π*) transitions of the CHCl2CO2 ligands, respectively. The IR spectra of this compound showed two strong stretching vibrations bands, indicating a bridging coordination mode of the carboxylic group by presence of νasym (M2M'O) vibrations of the ligand in the infrared spectra.               KEY WORDS: Oxo-centered, Trinuclear complexes, Carboxylic ligand, Crystallographic data, IR spectra Bull. Chem. Soc. Ethiop. 2018, 32(3), 491-500.DOI: https://dx.doi.org/10.4314/bcse.v32i3.

Fabrication of Perovskite-type Oxide BaPbO3 Nanoparticles and their Efficiency in Photodegradation of Methylene Blue

BaPbO3 perovskite was prepared by the sol-gel method. The physical and chemical properties of catalyst were characterized by XRD, TEM, SEM, EDX and IR techniques. The photocatalytic activity of the sample was evaluated by photocatalytic decomposition of methylene blue (MB) dye under UV irradiation. The results of XRD indicate that the perovskite-type oxide (BaPbO3) is crystal at 700 °C. The XRD, TEM and SEM revealed that BaPbO3 particles are prepared in the nano-size regime. The results show that the degradation efficiency of methylene blue (MB) by BaPbO3 is higher than rutile under similar conditions.Keywords: Perovskite-type oxide, nanopowder, dye removal, methylene blue

Microwave-promoted solvent free one-pot synthesis of triazolo[1,2-a] indazole-triones catalyzed by silica-supported La0.5Ca 0.5CrO3 nanoparticles as a new and reusable perovskite-type oxide

Microwave assisted solvent free synthesis of triazolo[1,2-a]indazole-1,3,8-triones through one-pot three-component reaction of dimedone, phenyl urazole and aromatic aldehydes is presented. The reaction process was catalyzed by La0.5Ca0.5CrO3 and silica-supported La0.5Ca0.5CrO3 nanoparticles as new perovskite-type catalysts. The nano catalyst was studied by XRD, SEM and IR characterization tools. Some advantages of the proposed approach include high yield, being eco-friendly, procedure convenience and reusability of the catalyst.               KEY WORDS: One-pot reaction, Triazolo[1,2-a]indazole trione, Perovskite oxide, Nano catalyst, Microwave, Solvent-free Bull. Chem. Soc. Ethiop. 2018, 32(2), 239-248.DOI: https://dx.doi.org/10.4314/bcse.v32i2.

STR-944: EFFECTS OF FINITE ELEMENT MODELLING APPROACH FOR PRESTRESSING SYSTEM ON THE PRESSURE CAPACITY OF A CANDU CONTAINMENT STRUCTURE

The primary objective of this article is to investigate the response of a CANDU®1 nuclear power plant containment structure to a much higher internal pressure that could be encountered during a severe accident. In this study, for the prestressed containment structure, a detailed model is obtained by a full 3D model. Nonlinear finite element method is employed to predict the response of the structure using ANSYS software. The major challenges for modelling prestressing tendon elements are to accommodate parameters affecting prestressing forces. In previous research studies, the prestressing system is modelled using an equivalent pressure and tendon end forces, and tendons are modelled as smeared reinforcement in the concrete elements. In this study, the prestressing tendons are modelled using discrete elements. This method enables the capability of the model to update the prestressing forces accommodating the non-uniform losses. The difference in the response of the structure using the discrete model for the prestressing tendons and the smeared approach is 15 percent. It is observed that the containment structure, meets the design requirements of the current standards as it behaves linearly up to 1.5 times the design pressure, and the ultimate pressure capacity is estimated as 2.7 times the design pressure. The ultimate pressure capacity is reached when the prestressing tendon rupture at the dome

Extending the solid step fixed-charge transportation problem to consider two-stage networks and multi-item shipments

This paper develops a new mathematical model for a capacitated solid step fixed-charge transportation problem. The problem is formulated as a two-stage transportation network and considers the option of shipping multiple items from the plants to the distribution centers (DC) and afterwards from DCs to customers. In order to tackle such an NP-hard problem, we propose two meta-heuristic algorithms; namely, Simulated Annealing (SA) and Imperialist Competitive Algorithm (ICA). Contrary to the previous studies, new neighborhood strategies maintaining the feasibility of the problem are developed. Additionally, the Taguchi method is used to tune the parameters of the algorithms. In order to validate and evaluate the performances of the model and algorithms, the results of the proposed SA and ICA are compared. The computational results show that the proposed algorithms provide relatively good solutions in a reasonable amount of time. Furthermore, the related comparison reveals that the ICA generates superior solutions compared to the ones obtained by the SA algorithm

Fabrication and Antibacterial Performance of Nano-silver-Doped Monoliths by the Sol-Gel Method

The organic-inorganic hybrids of glycine, tetraethylortho silicate (TEOS) and triethylphosphate (TEP) doped with silver ions were prepared by the sol-gel method. After moulding and heating at 600 °C to remove organic compound, porous Ag/P2O5-SiO2 monoliths were obtained. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectrum, transmission electron microscopy (TEM), infrared spectroscopy (FT-IR) and scanning tunnelling microscopy (STM) were used to structurally study monoliths. Surface area, pore volume and swelling degree of the samples were adjusted with different contents of TEP in the starting composition. Ag ions were stably released into the water at 30 °C for 28 days. Antibacterial experimentation revealed that such materials, treated at 600 °C, could restrain Escherichia coli effectively.KEYWORDS Antibacterial effect, nano-silver, phosphorous, organic–inorganic hybrid, sol-gel.

Efficientone-pot synthesis of imidazoles catalyzed by silica-supported La0.5Pb0.5MnO3 nano particles as anovel and reusable perovskite oxide

Silica-supported La0.5Pb0.5MnO3 nanoparticles was prepared and used as a new perovskite-type catalyst for rapid and efficient synthesis of substituted imidazoles by an one-pot three-component condensation of [9,10]-phenanthraquinone, aryl aldehydes and ammonium acetate in excellent yield under reflux, and also solvent-free conditions

Global, Regional, and National Life Expectancy, All-Cause Mortality, and Cause-Specific Mortality for 249 Causes of Death, 1980-2015: A Systematic Analysis for the Global Burden of Disease Study 2015

Background Improving survival and extending the longevity of life for all populations requires timely, robust evidence on local mortality levels and trends. The Global Burden of Disease 2015 Study (GBD 2015) provides a comprehensive assessment of all-cause and cause-specific mortality for 249 causes in 195 countries and territories from 1980 to 2015. These results informed an in-depth investigation of observed and expected mortality patterns based on sociodemographic measures. Methods We estimated all-cause mortality by age, sex, geography, and year using an improved analytical approach originally developed for GBD 2013 and GBD 2010. Improvements included refinements to the estimation of child and adult mortality and corresponding uncertainty, parameter selection for under-5 mortality synthesis by spatiotemporal Gaussian process regression, and sibling history data processing. We also expanded the database of vital registration, survey, and census data to 14 294 geography-year datapoints. For GBD 2015, eight causes, including Ebola virus disease, were added to the previous GBD cause list for mortality. We used six modelling approaches to assess cause-specific mortality, with the Cause of Death Ensemble Model (CODEm) generating estimates for most causes. We used a series of novel analyses to systematically quantify the drivers of trends in mortality across geographies. First, we assessed observed and expected levels and trends of cause-specific mortality as they relate to the Socio-demographic Index (SDI), a summary indicator derived from measures of income per capita, educational attainment, and fertility. Second, we examined factors affecting total mortality patterns through a series of counterfactual scenarios, testing the magnitude by which population growth, population age structures, and epidemiological changes contributed to shifts in mortality. Finally, we attributed changes in life expectancy to changes in cause of death. We documented each step of the GBD 2015 estimation processes, as well as data sources, in accordance with Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). Findings Globally, life expectancy from birth increased from 61.7 years (95% uncertainty interval 61.4-61.9) in 1980 to 71.8 years (71.5-72.2) in 2015. Several countries in sub-Saharan Africa had very large gains in life expectancy from 2005 to 2015, rebounding from an era of exceedingly high loss of life due to HIV/AIDS. At the same time, many geographies saw life expectancy stagnate or decline, particularly for men and in countries with rising mortality from war or interpersonal violence. From 2005 to 2015, male life expectancy in Syria dropped by 11.3 years (3.7-17.4), to 62.6 years (56.5-70.2). Total deaths increased by 4.1% (2.6-5.6) from 2005 to 2015, rising to 55.8 million (54.9 million to 56.6 million) in 2015, but age-standardised death rates fell by 17.0% (15.8-18.1) during this time, underscoring changes in population growth and shifts in global age structures. The result was similar for non-communicable diseases (NCDs), with total deaths from these causes increasing by 14.1% (12.6-16.0) to 39.8 million (39.2 million to 40.5 million) in 2015, whereas age-standardised rates decreased by 13.1% (11.9-14.3). Globally, this mortality pattern emerged for several NCDs, including several types of cancer, ischaemic heart disease, cirrhosis, and Alzheimer\u27s disease and other dementias. By contrast, both total deaths and age-standardised death rates due to communicable, maternal, neonatal, and nutritional conditions significantly declined from 2005 to 2015, gains largely attributable to decreases in mortality rates due to HIV/AIDS (42.1%, 39.1-44.6), malaria (43.1%, 34.7-51.8), neonatal preterm birth complications (29.8%, 24.8-34.9), and maternal disorders (29.1%, 19.3-37.1). Progress was slower for several causes, such as lower respiratory infections and nutritional deficiencies, whereas deaths increased for others, including dengue and drug use disorders. Age-standardised death rates due to injuries significantly declined from 2005 to 2015, yet interpersonal violence and war claimed increasingly more lives in some regions, particularly in the Middle East. In 2015, rotaviral enteritis (rotavirus) was the leading cause of under-5 deaths due to diarrhoea (146 000 deaths, 118 000-183 000) and pneumococcal pneumonia was the leading cause of under-5 deaths due to lower respiratory infections (393 000 deaths, 228 000-532 000), although pathogen-specific mortality varied by region. Globally, the effects of population growth, ageing, and changes in age-standardised death rates substantially differed by cause. Our analyses on the expected associations between cause-specific mortality and SDI show the regular shifts in cause of death composition and population age structure with rising SDI. Country patterns of premature mortality (measured as years of life lost [YLLs]) and how they differ from the level expected on the basis of SDI alone revealed distinct but highly heterogeneous patterns by region and country or territory. Ischaemic heart disease, stroke, and diabetes were among the leading causes of YLLs in most regions, but in many cases, intraregional results sharply diverged for ratios of observed and expected YLLs based on SDI. Communicable, maternal, neonatal, and nutritional diseases caused the most YLLs throughout sub-Saharan Africa, with observed YLLs far exceeding expected YLLs for countries in which malaria or HIV/AIDS remained the leading causes of early death. Interpretation At the global scale, age-specific mortality has steadily improved over the past 35 years; this pattern of general progress continued in the past decade. Progress has been faster in most countries than expected on the basis of development measured by the SDI. Against this background of progress, some countries have seen falls in life expectancy, and age-standardised death rates for some causes are increasing. Despite progress in reducing age-standardised death rates, population growth and ageing mean that the number of deaths from most non-communicable causes are increasing in most countries, putting increased demands on health systems. Copyright (C) The Author(s). Published by Elsevier Ltd