Fabrication of PZT-polymer composite materials having 3-3 connectivity for hydrophone applications

Lanthanum-modified lead zirconate titanate (PZT) powder and volatilisable polymethylmethacrylate (PMM) polymer particles have been used for fabrication of porous sintered ceramics of interconnected porosity varying from 25% to 59%. Sintered ceramics are converted into piezoelectric PZT-polymer composites by incorporating silicone rubber elastomer followed by electroding and poling. Influence of the variation of PZT-PMM ratio and sintering temperatures on the open and closed porosity of the sintered ceramics as well as volume fraction PZT in the composites has been studied and correlated for the optimization of piezoelectric properties. The PZT-polymer composites possess low density, considerably high piezoelectric voltage coefficient and considerably lower ageing characteristics and are therefore considered suitable for designing highly sensitive hydrophone systems.     

A study of the new K2NiF4-type solid solutions Sr2FexRu1−xO4 by Mőssbauer spectroscopy and other techniques

The magnetic and structural properties of the solid solutions Sr₂Fe_xRu_1?xO₄ (O ? x ? 0.5) have been studied using ⁵⁷Fe and ⁹⁹Ru Mőssbauer spectroscopy and other techniques. These phases, which are reported for the first time, have the K₂NiF₄-type structure with iron and ruthenium distributed at random on the B-site. As the ruthenium is replaced by iron the weakly-metallic conductivity and Pauli paramagnetism of Sr₂RuO₄ give way to localized-electron behaviour and long-range antiferromagnetic order despite the layer-type structure which is unfavourable for 180° Ru-O-M (M = Fe or Ru) magnetic exchange interactions in three dimensions. For x = 0.1-0.4 the iron is present almost entirely in the +3 oxidation state, but for x = 0.5 appreciable amounts of Fe^IV are also present, in conjunction with Fe^III, Ru^IV, and Ru^V.     

Mixed boundary value problem of an infinite thick elastic slab containing a flat annular crack under torsion

In the present paper we consider the problem of determining the stress distribution in an infinitely long isotropic, compressible, homogeneous elastic slab containing a flat annular crack which is opened by internal shear stress. The faces of the slab are assumed to be stress free and the crack is located in the middle plane of the slab. The problem is formulated in triple integral equations which reduce to an infinite system of simultaneous equations, which are solved numerically.     

The torsion of a microelastic half-space by a flat annular rigid stamp

The present paper seeks to solve the problem of an elastic half space under torsion by a flat annular rigid stamp in the linear micropolar elasticity. The problem is reduced to the solution of a system of four Fredholm integral equations of the second kind in four unknown functions. An iterative solution of these integral equations has been obtained for $\text{λ = a/b ? 1}$ for the case of simple rotation through a small angle $\text{ω}{}_0$ and the corresponding classical results have been obtained.     

Enhanced SO2 concentrations observed over northern India: role of long-range transport

The combustion of fossil fuels (coal and petroleum products) constitutes a source of continuous release of anthropogenic SO₂ into the atmosphere. Furthermore, natural sources such as volcanoes can inject large amounts of SO₂ directly into the troposphere and sometimes even into the stratosphere. These event-based volcanic eruptions provide solitary opportunities to study the transport and transformation of atmospheric constituents. In this study, we present an episode of high SO₂ concentration over northern India as a result of long-range transport from Africa using multiple satellite observations. Monthly averaged column SO₂ values over the Indo-Gangetic Plain (IGP) were observed in the range of 0.6–0.9 Dobson units (DU) during November 2008 using observations from the Ozone Monitoring Instrument (OMI). These concentrations were conspicuously higher than the background concentrations (<0.3 DU) observed during 2005–2010 over this region. The columnar SO₂ loadings were highest on 6 November over most of the IGP region and even exceeded 6 DU, a factor of 10–20 higher than background levels in some places. These enhanced SO₂ levels were not reciprocated in satellite-derived NO₂ or CO columns, indicating transport from a non-anthropogenic SO₂ source. As most of the local aerosols over the IGP region occur below 3 km, a well-separated layer at 4–5 km was observed from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. Wind fields and back-trajectory analysis revealed a strong flow originating from the Dalaffilla volcanic eruption in Ethiopia during 4–6 November 2008. Although volcanic SO₂ plumes have been extensively studied over many parts of Asia, Europe, and the USA, analysis of such events for the IGP region is being reported for the first time in this study.     

Congenital Y-type urethro-perineal fistula

A case of primary carcinoma of the urinary bladder associated with a primary retroperitoneal leiomyosarcoma is presented. Due to the lack of early symptoms, diagnosis of the retroperitoneal leiomyosarcoma was late and therefore the prognosis was poor. Twelve months after diagnosis the patient died not of the bladder tumor, but of the recurrent leiomyosarcoma.     

A conformal cylindrical microstrip array for producing omnidirectional radiation pattern

Radiation patterns of rectangular microstrip patches arranged circumferentially on a circular cylinder have been computed. Both the axial patches and circumferential patches have been used. It has been found that the number of circumferential patches required for a given ripple in gain pattern is considerably less, thus simplifying the feed network. Comparison with experimental measurements shows good agreement.     

The First Example of Saccharin‐Lithium Bromide Catalysis: Direct Synthesis of N‐Tosylimines from Alcohols

The first procedure to access N‐tosylimines directly from alcohols under mild and neutral conditions is reported. The protocol involves saccharin‐lithium bromide‐catalyzed oxidation of alcohols to aldehydes/ketones with chloramine‐T followed by their condensation with the in situ generated oxidation by‐product p‐toluenesulfonamide in the same reaction vessel to afford N‐tosylimines in 40–90% overall yields. The present work opens up a new and efficient synthetic route to N‐tosyimines directly from alcohols in a one‐pot procedure.