Phase transfer of platinum nanoparticles from aqueous to organic solutions using fatty amine molecules

In this report we demonstrate a simple process based on amine chemistry for the phase transfer of platinum nanoparticles from an aqueous to an organic solution. The phase transfer was accomplished by vigorous shaking of a biphasic mixture of platinum nanoparticles synthesised in an aqueous medium and octadecylamine (ODA) in hexane. During shaking of the biphasic mixture, the aqueous platinum nanoparticles complex via either coordination bond formation or weak covalent interaction with the ODA molecules present in the organic phase. This process renders the nanoparticles sufficiently hydrophobic and dispersible in the organic phase. The ODA-stabilised platinum nanoparticles could be separated out from hexane in the form of a powder that is readily redispersible in weakly polar and non-polar organic solvents. The ODA-capped platinum nanoparticles show high catalytic activity in hydrogenation reactions and this is demonstrated in the efficient conversion of styrene to ethyl benzene. The nature of binding of the ODA molecules to the platinum nanoparticles surface was characterised by thermogravimetry, transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR)

NUMERICAL STUDY OF STRESSES IN DENTAL MATERIALS BY USING FINITE ELEMENT ANALYSIS

Dental tooth is made of different materials such as soft, hard and intermediate materials. PMMA is the softer material but it is associated with poor mechanical properties. It has been documented that the strength of PMMA is increased by incorporation of Zirconia as filler material. The objective of this study is to find out the optimum or best material which overcome the disadvantages of both PMMA and Zirconia and gives the optimum composition with increased mechanical properties. For this purpose 3D model of tooth is generated and for different materials as per there mechanical properties such as modulus of elasticity density and Poisson’s ratio this tooth model is analyzed in finite element analysis at constant loading conditio

IMPLEMENTATION OF TWO-CAVITY METHOD FOR MEASURING THE FLOW RESISTIVITY OF ACOUSTIC MATERIAL

Acoustic materials are characterized according to their macroscopic and microscopic properties. The sound absorption co-efficient and the air-flow resistivity are of paramount importance among those used to describe the acoustic behaviour of materials. There are several methods developed for measuring the air-flow resistivity of acoustic material. The aim of this paper is to study the existing static flow resistivity measurement methods and then accordingly implement a suitable indirect method based on standard impedance tube. The flow resistivity measurements are carried out for additive manufactured ABS (Acrylonitrile butadiene styrene) sample, foam and glass fibre using the two-cavity method. There are certain similarities observed in their results. Further analysis of the raw impedance data is carried out and conclusions are drawn pertaining to the performance and feasibility of the implemented method

Implementation of Two-cavity Method for Measuring the Flow Resistivity of Acoustic Material

Acoustic materials are characterized according to their macroscopic and microscopic properties. The sound absorption co-efficient and the air-flow resistivity are of paramount importance among those used to describe the acoustic behaviour of materials. There are several methods developed for measuring the air-flow resistivity of acoustic material. The aim of this paper is to study the existing static flow resistivity measurement methods and then accordingly implement a suitable indirect method based on standard impedance tube. The flow resistivity measurements are carried out for additive manufactured ABS (Acrylonitrile butadiene styrene) sample, foam and glass fibre using the two-cavity method. There are certain similarities observed in their results. Further analysis of the raw impedance data is carried out and conclusions are drawn pertaining to the performance and feasibility of the implemented method

Linear superclusters of colloidal gold particles by electrostatic assembly on DNA templates

The organization of nanoparticles into superstructures of predefined geometry is an important challenge in the area of nanoscale architecture. Attractive Coulombic interaction between positively charged amine groups on gold particle surfaces and negatively charged phosphate backbones of DNA molecules drives the self-assembly of gold nanoparticles into linear supercluster structures

Preparation, characterization and mechanistic features of zirconia films on bare and functionalized gold surfaces

Electrochemical synthesis of microcrystalline ZrO<SUB>2</SUB> at room temperature on bare and functionalized gold surfaces is reported to illustrate the biomimetic conditions of nucleation and growth. ZrO<SUB>2</SUB> films prepared on self-assembled monolayers (SAMs) of pentane-1,5-dithiol (PDT) on polycrystalline gold surfaces reveal a high degree of orientation and a distinct cleavage face, in contrast to monoclinic films, obtained on bare gold surfaces at room temperature. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), impedance measurement, current-transients, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to follow the monolayer formation, Zr-attachment on the SAM-modified surface and subsequent difference in nucleation conditions of ZrO<SUB>2</SUB> formation. The role of SAMs in controlling the size and habit during crystallization of ZrO<SUB>2</SUB> is discussed in terms of a proposed reaction mechanism

A highly selective ammonia gas sensor using surface-ruthenated zinc oxide

Preparation and characterisation of a highly selective surface-ruthenated zinc oxide sensor for ammonia in trace levels is demonstrated. The introduction of some RuO linkages on the surface of ZnO leads to a dramatic enhancement in the sensitivity (S) to 1000 ppm level of ammonia at 300°C (S=440) as compared to the similar response obtained for pure ZnO (S=1.5). A systematic study using various characterisation techniques such as EDAX, SEM, CV and XPS indicates the key role played by the amount and distribution of Ru species on the surface

A Performance Study on Indirect Static Flow Resistivity Measurement Methods for Acoustic Materials

Abstract: Various empirical models have emphasized the dependence of sound absorption coefficient on static airflow resistivity, and thus its measurement becomes essential. In this paper, the two-cavity and two-thickness indirect acoustic methods are implemented based on a standard impedance tube for evaluating the static flow resistivity of foam. A comparison is made between the resistivity results obtained by the two-cavity and two-thickness method, and later validated with results of an alternating air-flow test setup which is developed as per the ISO 9053 guidelines. Further, the empirical relations are utilized to estimate the absorption coefficient from measured values of flow resistivity and are compared with measured absorption coefficient in an impedance tube. The results discussed in this study presents the feasibility and suitability of the indirect acoustic methods for evaluating the flow resistivity