2,494 research outputs found
Elastic properties of Zr-based bulk metallic glasses studied by resonant ultrasound spectroscopy
No full textWe report measurements of the elastic properties of Zr-based bulk metallic glasses,
Zr52.5Cu17.9Ni14.6Al10Ti5, Zr50Cu30Ni10Al10, and Zr50Cu40Al10 between 5 K and
300 K. Both the shear and longitudinal modulus have been measured as a function of
temperature, allowing accurate determination of the Poisson’s ratio and the related
ratio of bulk modulus to shear modulus, K/G. These data make it possible to assess the
influence of the alloy’s composition on the mechanical properties and enable an
evaluation of the correlation between the elastic moduli and the ductility of the alloys
Homochiral BINAPDA-Zr-MOF for Heterogeneous Asymmetric Cyanosilylation of Aldehydes
No full textA new
homochiral BINAPDA-Zr-MOF was prepared by a new chiral
organic linker of (R)-4,4′-(6,6′-dichloro-2,2′-diethoxyl-[1,1′-binaphthalene]-4,4′-diyl)dibenzoic
acid (R-L) and ZrCl4 under
solvothermal conditions. Its structure was determined by Pawley refinement
on the basis of the measured PXRD pattern determined for BINAPDA-Zr-MOF, and it showed that the obtained chiral MOF crystallized in the F23 space group with the same topological structure
as that of UiO-66. The obtained BINAPDA-Zr-MOF can be
a very active catalyst to catalyze aldehyde cyanosilylation. In addition,
the chiral BINAPDA-Zr-MOF was a typical solid catalyst,
which was proved by a hot leaching test; moreover, it could be reused
at least five times without loss of its catalytic activity and enantioselectivity
Surface features of Zr-based and Ti-based metallic glasses by ion irradiation
No full textDue to a lack of crystalline structures and grain boundaries, metallic glasses exhibit extremely high strength and superior resistance to corrosion. They are also supposed to be resistant against displacive irradiation due to their inherent disordered structure, thereby are potential candidates for applications in irradiation environments. In this work, the irradiation effects of Zr- and Ti- based bulk metallic glasses (BMGs) under heavy ions irradiation were investigated. The results showed that the Zr-based BMG is more resistant to the Cl ion irradiation with no structural transition and distinct damage subjected to high irradiation fluence. In contrast, the Ti-based BMG exhibits unique damage morphology with respect to the Zr-based BMG and other reported metallic glasses material. Two kinds of damage pits in micrometer scale form on the irradiated surface, and distinct viscous flow takes place. The formation mechanism of the unique irradiation damage feature is discussed
Supplementary information files for "Recommended solutions for the disinfection of Ti-Zr-cu-pd bulk metallic glasses"
No full textSupplementary files for article "Recommended solutions for the disinfection of Ti-Zr-cu-pd bulk metallic glasses"Disinfection of medical devices is crucial to patient safety. Notably, an incorrect selection of disinfectant can damage the material surface and impact its performance. Ti-Zr-Cu-Pd bulk metallic glasses (BMGs) show considerable potential for biomedical use, however standard sterilisation protocols remain undeveloped. This study evaluates the effects of common clinical disinfection solutions, including NaOH, NaClO, and Virkon®, on Ti-Zr-Cu-Pd BMGs, to assess their impact on surface characteristics (chemical composition, surface free energy) and on biocompatibility (pre-osteoblast cells behaviour). The findings aim to inform practical guidelines for safe and effective cleaning and sterilisation of devices that contain these alloys.© The Author(s), CC BY 4.0</p
Microstructure of Zr-alloyed coating using pulsed laser
No full textCoatings were synthesized by laser alloying of zirconium (Zr) particles using a pulsed Nd:YAG laser on an austenite stainless steel. The distribution of Zr is uneven, in a depth of 18 mum just below the surface of the pool. The coating consisted of duplex microstructures, i.e. metallic glass (MG) and austenite. The MG formed in Zr-contained regions, with the Zr composition ranging from 7.6 to 16.8 at.%. The formation of the MG was attributed to an increase in glass-forming ability by Zr addition
Comparative study of the dry reforming of methane on fluidised aerogel and xerogel Ni/Al2O3 catalysts
No full textThe xerogel and aerogel Ni(20 wt %)/Al2O3 catalysts were prepared through incipient-wetness-impregnation and co-precipitation-supercritical drying (CP-SCD), respectively. All the fresh and used catalysts were well characterised using FESEM, BET, XRD, H2-TPR and H2-TPD techniques. Their properties and catalytic performance in dry reforming of CH4 in a fluidised bed reactor were comparatively investigated. In comparison with the xerogel catalyst, the aerogel catalyst possessed smaller crystallite size of nickel, larger specific surface area, higher nickel dispersion, lower bulky density and better fluidization quality. More importantly, the aerosol catalyst showed higher catalytic activity, stability and less carbon deposition in dry reforming, due to the excellent physicochemical properties of the aerogel catalyst and its enhanced fluidization quality
Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity
Get PDFBecause of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)
Elastic, mechanical, electronic, and defective properties of Zr-Al-C nanolaminates from first principles
No full textBy means of first principles calculations, Zr-Al-C nanolaminates have been studied in the aspects of chemical bonding, elastic properties, mechanical properties, electronic structures, and vacancy stabilities. Although the investigated Zr-Al-C nanolaminates show crystallographic similarities, their predicated properties are very different. For (ZrC)(n)Al3C2 (n=2, 3, 4), the Zr-C bond adjacent to the Al-C slab with the C atom intercalated in the Zr layers is the strongest, but the one with the C atom intercalated between the Zr layer and Al layer is the weakest. In contrast, the situation for (ZrC)(n)Al4C3 (n=2, 3) is just the opposite. For Zr-Al-C nanolaminates, the calculated bulk, shear and Young's modulus increase in the sequence of Zr2AlC<Zr3AlC2<Zr2Al4C5<Zr3Al4C6<Zr2Al3C4<Zr3Al3C5<Zr4Al3C6. The (ZrC)(n)Al3C2 (n=2, 3, 4) series exhibit the most outstanding elastic properties. In the presence of the external pressure, the bulk and shear moduli exhibit a linear response to the pressure, except for Zr2AlC and Zr3AlC2, both of which belong to the so-called MAX phases. The two materials also exhibit very distinct properties in the strain-stress relationship, electronic structures and vacancy stabilities. As the intercalated Al layers increase, the formation energy of V-Zr and V-Al increases, while the formation energy of V-C decreases
Simple synthesis, characterization and mechanism of Fe/Zr bimetallic-organic framework for Cr (VI) removal from wastewater
No full textIron-zirconium bimetallic metal-organic frameworks (MOFs) materials were synthesized by a one-step solvothermal method with abundant active sites for the efficient removal of Cr (VI) ions from wastewater. The as-prepared Fe/Zr-MOFs composites were analyzed by the XRD, FTIR, SEM, TEM, and XPS. The effects of temperature, pH, initial Cr (VI) ion concentration, and co-existing ions on the adsorption properties of the Fe/Zr-MOFs composites were verified. The best removal efficiency of the Fe/Zr-MOFs composites was observed at pH = 5, with the concentration of Cr (VI) ion 20 mg/L under 303 K. In addition, the adsorption process of Cr (VI) by Fe/Zr-MOFs materials consisted with the Langmuir isothermal adsorption model, indicating that the adsorption process is a predominantly uniform monolayer adsorption. Kinetic modelling confirmed that the adsorption process of the material is dual physical and chemical adsorption. The thermodynamic analysis confirmed that the adsorption of Cr (VI) by Fe/Zr-MOFs was a spontaneous feasible, heat-absorbing process. The removal rate was up to 82% after five cycle reused experiments, suggesting the potential practical application of the material. The outperformance of the as-prepared materials was attributed to the combination of the advantages of Fe-MOF and Zr-MOF. Of note, a possible adsorption mechanism was proposed. That is, the adsorption process of the material is a dual physical and chemical adsorption, which mainly includes electrostatic interactions, Chemical coordination, and redox reactions
The etiology of esophageal cancer in high- and low- risk areas of Jiangsu province, China
No full text [Background]Esophageal cancer (EC) remains one of the most common and fatal malignancies worldwide. The geographic variation in EC occurrence is striking, and China is an area with one of the highest incidences of EC. A number of epidemiological studies have been conducted toward EC in the past decades, results suggested that tobacco smoking, alcohol drinking, unhealthy dietary factors and chronic injuries of the esophageal mucosa are important in the development of this disease. Genetic polymorphisms in enzymes involved in metabolism of carcinogens may also influence individual susceptibility. However, the effects of major lifestyle and hereditary risk factors on the development of EC remain poorly understood in China. Moreover, little attention has been paid to the etiological heterogeneity between similar areas with great risk gradient. [Methods]From 2003 to 2007, a large population-based case-control study of EC has been conducted in a selected high-risk area and a selected low-risk area of Jiangsu Province, one of the highest cancer incidence areas in China. In total, 1,520 cases and 3,879 controls were recruited. In this thesis, we evaluated the role of major lifestyle factors such as tobacco smoking, alcohol drinking and dietary factors, as well as inherited determinants including family history of cancer and genetic polymorphisms of alcohol-metabolizing related genes on the risk of EC. In addition, we investigated how much of the risk gradient between two areas could be explained by variation in the distributions of major risk factors. [Results] Tobacco smoking and alcohol drinking moderately increased the risk of EC, while the positive associations were only found among men but not among women. Dietary factors were observed to play important roles in the development of EC. Specific dietary habits i.e., fast eating speed, and hot eating and/or drinking substantially elevated EC risk and could explain more than 20% of EC cases each. High intake of salty foods and fried foods, low consumption of raw garlic were also observed to increase the risk of EC. In addition to environmental and lifestyle factors, we confirmed that a positive family history can significantly increase EC risk, and found the inheritance may modify the effect of some unhealthy lifestyles. Moreover, we further explored the relationship between EC and single nucleotide polymorphismsof ADH1B, ADH1C and ALDH2 genes. Results showed that the slow metabolizing ADH1B G allele, ADH1C G allele and ALDH2 A allele significantly increased EC risk among moderate-to-heavy alcohol drinkers, and a significant interaction was observed between ALDH2 gene and alcohol consumption. Lastly, we found that more than 60% of EC cases could be attributable to major lifestyle risk factors in the study population; furthermore, dissimilar distribution of several lifestyle factors, together with variations of hereditary factors may be largely responsible for the incidence difference between two study areas. [Conclusion]The findings in this thesis confirm that unhealthy lifestyles including smoking, alcohol drinking and some dietary factors are the predominant risk factors of EC in China, and a large proportion of incidence difference between regions at varying risk could be attributed to the different prevalence of lifestyle factors. As most of the identified risk factors are modifiable, these could be translated into risk reduction prevention programs in China, and a substantial proportion of new EC cases are expected to be prevented by eliminating or avoiding these risk factors in the population. </p
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