Sol-gel processing: A versatile concept for special glasses and ceramics

The various parameters related to sol-gel processing are discussed with special reference to those which usually attract less attention but depending on the final product in mind, can play important roles. The versatility of the sol-gel technique in materials preparation is demonstrated by discussing the various products developed at the author’s laboratory by using this processing method.     

Pixel rearrangement based statistical restoration scheme reducing embedding noise

In this paper, a block based steganographic algorithm has been proposed where a sequence of secret bits are embedded into a set of pixels by rearranging the pixel locations. This algorithm has been devised as an improvement over existing statistical restoration based algorithms in order to reduce the additive noise which occurs due to embedding. It is shown that the proposed scheme substantially reduces the additive noise compared to existing statistical restoration based schemes.     

Composite bending-dominated hollow nanolattices: A stiff,cyclable mechanical metamaterial

Manufacturing ultralight and mechanical reliable materials has been a long-time challenge. Ceramic-based mechanical metamaterials provide significant opportunities to reverse their brittle nature and unstable mechanical properties and have great potential as strong, ultralight, and ultrastiff materials. However, the failure of ceramics nanolattice and degradation of strength/modulus with decreasing density are caused by buckling of the struts and failure of the nodes within the nanolattices, especially during cyclic loading. Here, we explore a new class of 3D ceramic-based metamaterials with a high strength–density ratio, stiffness, recoverability, cyclability, and optimal scaling factor. Deformation mode of the fabricated nanolattices has been engineered through the unique material design and architecture tailoring. Bending-dominated hollow nanolattice (B-H-Lattice) structure is employed to take advantages of its flexibility, while a few nanometers of carbonized mussel-inspired bio-polymer (C-PDA) is coherently deposited on ceramics’ nanolayer to enable non-buckling struts and bendable nodes during deformation, resulting in reliable mechanical properties and outperforming the current bending-dominated lattices (B-Lattices) and carbon-based cellulose materials. Meanwhile, the structure has comparable stiffness to stretching-dominated lattices (S-Lattices) while with better cyclability and reliability. The B-H-Lattices exhibit high specific stiffness (>10⁶?Pa·kg^?1·m^?3), low-density (～30?kg/m³), buckling-free recovery at 55% strain, and stable cyclic loading behavior under up to 15% strain. As one of the B-Lattices, the modulus scaling factor reaches 1.27, which is lowest among current B-Lattices. This study suggests that non-buckling behavior and reliable nodes are the key factors that contribute to the outstanding mechanical performance of nanolattice materials. A new concept of engineering the internal deformation behavior of mechanical metamaterial is provided to optimize their mechanical properties in real service conditions.     

Rare-earth doped zirconia fibres by sol-gel processing

Polycrystalline zirconia fibres, doped with 2–8 mol% of oxides of trivalent lanthanum, praseodymium, neodymium, samarium, gadolinium, and dysprosium (in decreasing cation size), were prepared by spinning of acetate-derived sols and baking the gel fibres thus obtained at 900–1300 °C for 1 h. The larger sized dopants lanthanum, praseodymium and neodymium (Group A) gave rise to tetragonal zirconia, with or without cubic zirconia, at 900 °C which converted partly or fully to monoclinic zirconia, in certain cases accompanied by a cubic zirconate phase at higher temperatures. The smaller sized dopants samarium, gadolinium and dysprosium (Group B) generated only tetragonal or cubic, or both polymorphs of zirconia, depending on the cation type, concentration and temperature. This stabilization of higher symmetry polymorphs with Group B dopants was associated with relatively large crystallite size (especially when calcined at 1300 °C). The maximum tensile strength values of usable fibres calcined at 1300 °C were found to decrease with increasing size in dopant dysprosium > gadolinium > samarium > neodymium, praseodymium, lanthanum=0). Although all the dopant cations were larger in size than Zr⁴⁺ (in the same oxygen coordination), the relative closeness in size of Group B cations with Zr⁴⁺ was considered to be the reason behind the obtained differences in properties.     

A negative association of schizophrenia with an allele of the HLA DQB1 gene among African-Americans

The present study investigated the relationship between the time of nocturnal onset of urinary 6-sulfatoxymelatonin (aMT6s) secretion, and the timing of the steepest increase in nocturnal sleepiness ("sleep gate"), as determined by an ultrashort sleep-wake cycle test (7 min sleep, 13 min wake). Twenty-nine men (mean age 23.8 +/- 2.7 years) participated. The ultrashort sleep-wake paradigm started at 0700 hr after a night of sleep deprivation and continued for 24 hr until 0700 hr the next day. Electrophysiological recordings were carried out during the 7-min sleep trials, which were then scored conventionally for sleep stages. Urinary aMT6s was measured every 2 hr. The results showed that the timing of the sleep gate was significantly correlated with the onset of aMT6s secretion. These results are discussed in light of the possible role of melatonin in sleep-wake regulation.     

The political economy of metering agricultural tube wells in West Bengal,India

Unmetered electricity supply to agriculture has given rise to a unique and invidious water–energy–food nexus in India. Metering of agricultural consumers has been suggested as a way to break the nexus, but most states have not been able to meter farmers due to their opposition . The only exception is the state of West Bengal. Using primary data from a household survey conducted in 2010 when the metering process was still underway, this paper argues that farmers’ support for metering in West Bengal can be explained in terms of the economics of groundwater use and politics surrounding agriculture and groundwater in the state.     

A Clinical Trial to Test the Feasibility of a Telehealth Psychoeducational Intervention for Persons With Schizophrenia and Their Families: Intervention and 3-Month Findings.

Objective: To evaluate the feasibility of a telehealth psychoeducation intervention for persons with schizophrenia and their family members. Study Design: Randomized controlled trial. Participants: 30 persons with schizophrenia and 21 family members or other informal support persons. Interventions: Web-based psychoeducation program that provided online group therapy and education. Main Outcome Measures: Measures for persons with schizophrenia included perceived stress and perceived social support; for family members, they included disease-related distress and perceived social support. Results: At 3 months, participants with schizophrenia in the intervention group reported lower perceived stress (p = .04) and showed a trend for a higher perceived level of social support (p = .06). Conclusions: The findings demonstrate the feasibility and impact of providing telehealth-based psychosocial treatments, including online therapy groups, to persons with schizophrenia and their families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Li<Superscript>+</Superscript> ion conductivities in boro-tellurite glasses

Lithium ion conductivity has been investigated in a boro-tellurite glass system, LiCl.LiBO₂.TeO₂. In the absence of LiCl, the conductivity increases with increasing non-bridging oxygen (NBO) concentration. LiCl addition has little influence on total conductivity although the observed barriers are low. Formation of LiCl clusters appears evident. In the a.c. conductivity and dielectric studies, it is observed that the conductivity mechanism remains the same in all compositions and at all temperatures. A suggestion is made that Li⁺ ion transport may be driven by bridging oxygen ↔r non-bridging oxygen (BO ↔r NBO) switching, which is why the two different types of Li⁺ ions in the clusters and in the neighbourhood of NBOs, do not manifest in the conductivity studies.