65 research outputs found

    Electrophoretic deposition and corrosion behavior study of aluminum coating on AZ91D substrate

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    Aluminum coating was prepared on AZ91D magnesium alloy substrate using the electrophoretic deposition (EPD) method in absolute ethanol solvent. In order to determine the optimal concentration of AlCl3.6H2O additive, the zeta potential and size of particles in the suspension were measured in the presence of different concentrations of AlCl3.6H2O. The results showed that an appropriate coating is obtainable in the presence of  0.6 mM AlCl3.6H2O as an additive. The effects of applied voltage, deposition time, and additive concentration on deposition weight, deposition thickness, and coating morphology were also studied. A uniform coating with smaller pores and higher density was obtained at the additive concentration of 0.6 mM, deposition time of 18 min, and applied voltage of 70 V. The thickness of this coating was measured at about 256.91 µm. According to the results of corrosion behavior studies, the corrosion current density was measured at 29.16 and 12.85 µA/cm2 for uncoated and aluminum-coated AZ91D alloy, respectively

    Presenting an evaluation model of quantitative and qualitative indicators of green space in Mashhad

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    Urban green spaces are essential for the well-being of the population. However, due to various factors, the distribution of green spaces among city neighborhoods in quantitative and qualitative dimensions is often skewed. Hence, urban planners require effective tools to evaluate and analyze green spaces among the neighborhoods. The most common indicator used in green space assessment is the total area of green space to the total population, however, this index does not provide information on how green space is distributed in the city or region, as well as its ecosystem and ecological effects, which requires a more comprehensive study using new metrics. The aim of this study is to provide tools for a more comprehensive assessment to evaluate and plan better the location and quality of green spaces in the metropolis of Mashhad. For this a set of indicators for green spaces in a multidimensional framework was applied. The indicators considered (i) the total area of green spaces in relation to population and urban context, (ii) the quality of green spaces based on its size, density, the average Euclidean distance, and (iii) the accessibility of green spaces based on its shape, aggregation index, share of population supplied by GS, using the Geographic information system, Fragstats software. The proposed indicators were tested in seventeen municipalities of Mashhad. The results show that districts 17, 6 and 7 have the best and districts 15 and 16 which are among the least privileged areas of the city, have the worst situation of spatial distribution of green space in Mashhad

    4-(4-Pyrid­yl)pyridinium bis­(pyridine-2,6-dicarboxyl­ato)ferrate(III) tetra­hydrate

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    In the title compound, (C10H9N2)[Fe(C7H3NO4)2]·4H2O or (bpyH)[Fe(pydc)2]·4H2O, the asymmetric unit contains an [Fe(pydc)2]− (pydcH2= pyridine-2,6-dicarboxylic acid) anion, a protonated 4,4′-bipyridine as a counter-ion, (bpyH)+, and four uncoordinated water mol­ecules. The anion is a six-coordinate complex with a distorted octa­hedral geometry around the FeIII atom. A wide range of non-covalent inter­actions, i.e. O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, ion pairing, C—O⋯π [3.431 (2) Å] and C—H⋯π stacking inter­actions result in the formation of a three-dimensional network structure

    Fluid inclusion, zircon U-Pb geochronology, and O-S isotopic constraints on the origin and evolution of ore-forming fluids of the tashvir and varmazyar epithermal base metal deposits, NW Iran

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    Tashvir and Varmazyar deposits are part of the epithermal ore system in the Tarom–Hashtjin Metallogenic Belt (THMB), NW Iran. In both deposits, epithermal veins are hosted by Eocene volcanic-volcaniclastic rocks of the Karaj Formation and are spatially associated with late Eocene granitoid intrusions. The ore assemblages consist of pyrite, chalcopyrite, chalcocite, galena, and sphalerite (Fe-poor), with lesser amounts of bornite and minor psilomelane and pyrolusite. Fluid inclusion measurements from the Tashvir and Varmazyar revealed 182–287 and 194–285°C formation temperatures and 2.7–7.9 and 2.6–6.4 wt.% NaCl equivalent salinities, respectively. The oxygen isotope data suggested that the mineralizing fluids originated dominantly from a magmatic fluid that mixed with meteoric waters. The sulfur isotope data indicated that the metal and sulfur sources were largely a mixture of magma and surrounding sedimentary rocks. LA-ICP–MS zircon U–Pb dating of the granitoid intrusion at Tashvir and Varmazyar, yielded a weighted mean age of 38.34–38.31 and 40.85 Ma, respectively, indicating that epithermal mineralization developed between 40.85 and 38.31 Ma. Our data indicated that fluid mixing along with some fluid boiling were the main drives for hydrothermal alteration and mineralization at Tashvir and Varmazyar. All these characteristics suggested an intermediate-sulfidation epithermal style of mineralization. The THMB is proposed to be prospective for precious and base metal epithermal mineralization. Considering the extensional tectonic setting, and lack of advanced argillic lithocaps and hypersaline fluid inclusions, the THMB possibly has less potential for economically important porphyry mineralization

    Hydroxonium hydrate tris­(2,4,6-tri­amino-1,3,5-triazin-1-ium) bis­[bis­(pyri­dine-2,6-dicarboxyl­ato)cuprate(II)] pyridine-2,6-dicarboxylic acid hexa­hydrate

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    The reaction of copper(II) nitrate hexa­hydrate with pyridine-2,6-dicarboxylic acid (pydcH2) and 2,4,6-triamino-1,3,5-triazine (melamine) in aqueous solution in a 1:2:2 molar ratio gave the title compound, (H5O2)(C3H7N6)3[Cu(C7H3NO4)2]2·C7H5NO4·6H2O. The hydroxonium hydrate (H5O2)+, also known as the Zundel cation, resides on a twofold rotation axis. The O—H distance is 1.274 (14) Å, the O⋯O distance is 2.518 (5) Å, and the O—H—O angle is 162 (8)°. One of the melamine H+ cations, the uncoordinated pydcH2, and two water mol­ecules also reside on crystallographic twofold axes. The CuII atom has a tetra­gonally distorted octa­hedral coordination environment. The structure features extensive hydrogen bonding, with 21 distinct inter­actions. There is also a centrosymmetric C=O⋯π inter­action with an O⋯centroid distance of 3.288 (3) Å. The structure is similar to a mixed-valence manganese(II/III) structure but shows inter­esting differences in the metal-atom coordination. One of the water molecules is equally disordered with respect to a twofold axis

    A seromolecular study to determine the prevalence of cytomegalovirus in pregnant women referred to health centers in the north of Iran

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    Background and Objectives: Because of the controversial aspects of the CMV virus during pregnancy, it should be considered a serious health threat, especially in developing countries. The present seromolecular study aimed to determine cytomegalovirus prevalence in pregnant women referred to health centers in the north of Iran. Materials and Methods: One hundred and twenty-five pregnant women who were referred to health centers in Mazandaran province for regular health checks were randomly selected from Jan 2022 to Oct 2022. To detect the presence of the CMV genome and specific IgM and IgG antibodies against cytomegalovirus, the conventional PCR and ELISA tests were applied respectively. Results: All 125 pregnant women that attended the study were from Mazandaran province with a mean age of 30 years ranging from 20 to 42 years. The result showed that 2 (1.6%), 92 (73.6%), and 2 (1.6%) of the cases were positive for IgM, IgG, and IgM/IgG, respectively. The PCR test results indicated that the CMV DNA was present in 10 (8%) pregnant women. Our study shows that all PCR-positive cases were negative for the IgM test. Of the 10 PCR-positive samples 3 were positive and 1 was suspicious for the IgG test. Conclusion: Our study revealed that there is an urgent need for vaccination or other strategies to prevent and treat congenital CMV infection. Reducing the burden of congenital CMV infection requires global awareness. Further studies are recommended to obtain accurate estimates of the risk of congenital CMV infection

    Global, regional, and national prevalence of depression among cancer patients:A systematic review and meta-analysis

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    This systematic review and meta-analysis aimed to provide a summary of the existing evidence on the prevalence of depression among cancer patients worldwide to assist health policymakers in adopting appropriate measures to prevent and control depression in these patients. EMBASE, Google Scholar, Scopus, PubMed, and Web of Science databases were searched for original studies published in English from January 2000 to July 2019. The studies were screened on the basis of quality and relevance criteria. The statistical analyses were conducted in the R software. Out of 182,521 cancer patients examined in 183 studies, 49,280 (~27%) had depression (95% confidence interval [CI] = 24%-30%). The highest prevalence of depression was among patients with colorectal cancer with 32% (95% CI = 20%-47%). Among countries, Pakistan with 43% (95% CI = 26%-64%), and among continents, Africa with 36% (95% CI = 29%-43%) had the highest prevalence of reported depression in cancer patients. Adjusting for sample size, the prevalence of depression among female cancer patients, 31% (95% CI = 26%-36%), was higher than men, 26% (95% CI = 21%-31%). The prevalence of depression among cancer patients is increasing by an average of 0.6% per year. The findings show higher prevalence of depression among cancer patients in underdeveloped and developing countries compared to the developed nations and the global average

    Plasma nitriding of steels

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    This book focuses on the effect of plasma nitriding on the properties of steels. Parameters of different grades of steels are considered, such as structural and constructional steels, stainless steels and tools steels. The reader will find within the text an introduction to nitriding treatment, the basis of plasma and its roll in nitriding. The authors also address the advantages and disadvantages of plasma nitriding in comparison with other nitriding methods.

    Effect of Ceramic Surface Treatments after Machine Grinding on the Biaxial Flexural Strength of Different CAD/CAM Dental Ceramics

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    Objectives: This study aimed to evaluate the effect of different ceramic surface treatments after machining grinding on the biaxial flexural strength (BFS) of machinable dental ceramics with different crystalline phases. Materials and Methods: Disk-shape specimens (10mm in diameter and 1.3mm in thickness) of machinable ceramic cores (two silica-based and one zirconia-based ceramics) were prepared. Each type of the ceramic surfaces was then randomly treated (n=15) with different treatments as follows: 1) machined finish as control, 2) machined finish and sandblasting with alumina, and 3) machined finish and hydrofluoric acid etching for the leucite and lithium disilicate-based ceramics, and for the zirconia; 1) machined finish and post-sintered as control, 2) machined finish, post-sintered, and sandblasting, and 3) machined finish, post-sintered, and Nd;YAG laser irradiation. The BFS were measured in a universal testing machine. Data based were analyzed by ANOVA and Tukey's multiple comparisons post-hoc test (α=0.05). Results: The mean BFS of machined finish only surfaces for leucite ceramic was significantly higher than that of sandblasted (P=0.001) and acid etched surfaces (P=0.005). A significantly lower BFS was found after sandblasting for lithium disilicate compared with that of other groups (P<0.05). Sandblasting significantly increased the BFS for the zirconia (P<0.05), but the BFS was significantly decreased after laser irradiation (P<0.05).    Conclusions: The BFS of the machinable ceramics was affected by the type of ceramic material and surface treatment method. Sandblasting with alumina was detrimental to the strength of only silica-based ceramics. Nd:YAG laser irradiation may lead to substantial strength degradation of zirconia.
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