Preparation of acoustic lenses by mechanochemical synthesis and electrophoretic deposition of lead zirconium titanate (PZT) films

PZT powders has been synthesized via reactive dry milling using PbZrO3 and PbTiO3 as starting materials. Stabel suspensions of the PZT particles in ethanol (d50(Vol) = 115 nm) were obtained by a chemomechanical dispersion step. Teh electrophoretic deposition has been optimized varying the cell voltage and the PZT solid content in the suspension. PZT films have been deposited on platinum coated saphire. After drying, the films are densely packed and free of cracks. By using lithium acetate and lead acetate as a sinter aid it was possible to reduce the sintering temperature to 1050°C. A good electrode has been sputtered onto the piezoelectric films which then have been poled by the corona method. The circular PZT dots (...) with a thickness of 1 µm show the expected oscillation resonance at about 2 GHz and can be used in acoustic lenses, for example in acoustic microscopes

One-dimensional oxide nanostructures : growth, applications and devices

One dimensional (1D) inorganic materials are gaining high attention due to their structural stability and unique structural fatures. Among them, oxides are widely studied due to their well established application potential and mechanical as well as chemical stability. We have developed a generic approach for size-selective and site-specific growth of oxide nanowires by combination of a catalyst assisted growth mechanism and a molecular precursor approach, which is a viable alternative to other gas phase and solution procedures and produces well-defined (morphology and composition) materials

Cubic exact solutions for the estimation of pairwise haplotype frequencies: implications for linkage disequilibrium analyses and a web tool 'CubeX'

<p>Abstract</p> <p>Background</p> <p>The frequency of a haplotype comprising one allele at each of two loci can be expressed as a cubic equation (the 'Hill equation'), the solution of which gives that frequency. Most haplotype and linkage disequilibrium analysis programs use iteration-based algorithms which substitute an estimate of haplotype frequency into the equation, producing a new estimate which is repeatedly fed back into the equation until the values converge to a maximum likelihood estimate (expectation-maximisation).</p> <p>Results</p> <p>We present a program, "CubeX", which calculates the biologically possible exact solution(s) and provides estimated haplotype frequencies, D', r²and <it>χ</it>²values for each. CubeX provides a "complete" analysis of haplotype frequencies and linkage disequilibrium for a pair of biallelic markers under situations where sampling variation and genotyping errors distort sample Hardy-Weinberg equilibrium, potentially causing more than one biologically possible solution. We also present an analysis of simulations and real data using the algebraically exact solution, which indicates that under perfect sample Hardy-Weinberg equilibrium there is only one biologically possible solution, but that under other conditions there may be more.</p> <p>Conclusion</p> <p>Our analyses demonstrate that lower allele frequencies, lower sample numbers, population stratification and a possible |D'| value of 1 are particularly susceptible to distortion of sample Hardy-Weinberg equilibrium, which has significant implications for calculation of linkage disequilibrium in small sample sizes (eg HapMap) and rarer alleles (eg paucimorphisms, q < 0.05) that may have particular disease relevance and require improved approaches for meaningful evaluation.</p

Mining unexpected patterns using decision trees and interestingness measures: a case study of endometriosis

[[abstract]]Because clinical research is carried out in complex environments, prior domain knowledge, constraints, and expert knowledge can enhance the capabilities and performance of data mining. In this paper we propose an unexpected pattern mining model that uses decision trees to compare recovery rates of two different treatments, and to find patterns that contrast with the prior knowledge of domain users. In the proposed model we define interestingness measures to determine whether the patterns found are interesting to the domain. By applying the concept of domain-driven data mining, we repeatedly utilize decision trees and interestingness measures in a closed-loop, in-depth mining process to find unexpected and interesting patterns. We use retrospective data from transvaginal ultrasound-guided aspirations to show that the proposed model can successfully compare different treatments using a decision tree, which is a new usage of that tool. We believe that unexpected, interesting patterns may provide clinical researchers with different perspectives for future research.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙本[[booktype]]電子

Genome-Wide Data-Mining of Candidate Human Splice Translational Efficiency Polymorphisms (STEPs) and an Online Database

Variation in pre-mRNA splicing is common and in some cases caused by genetic variants in intronic splicing motifs. Recent studies into the insulin gene (INS) discovered a polymorphism in a 5' non-coding intron that influences the likelihood of intron retention in the final mRNA, extending the 5' untranslated region and maintaining protein quality. Retention was also associated with increased insulin levels, suggesting that such variants--splice translational efficiency polymorphisms (STEPs)--may relate to disease phenotypes through differential protein expression. We set out to explore the prevalence of STEPs in the human genome and validate this new category of protein quantitative trait loci (pQTL) using publicly available data.Gene transcript and variant data were collected and mined for candidate STEPs in motif regions. Sequences from transcripts containing potential STEPs were analysed for evidence of splice site recognition and an effect in expressed sequence tags (ESTs). 16 publicly released genome-wide association data sets of common diseases were searched for association to candidate polymorphisms with HapMap frequency data. Our study found 3324 candidate STEPs lying in motif sequences of 5' non-coding introns and further mining revealed 170 with transcript evidence of intron retention. 21 potential STEPs had EST evidence of intron retention or exon extension, as well as population frequency data for comparison.Results suggest that the insulin STEP was not a unique example and that many STEPs may occur genome-wide with potentially causal effects in complex disease. An online database of STEPs is freely accessible at http://dbstep.genes.org.uk/

Second primary malignancies after treatment for malignant lymphoma

To determine the incidence and possible causes of second primary malignancies after treatment for Hodgkin's and Non-Hodgkin's lymphoma (HL and NHL). A cohort of 3764 consecutive patients diagnosed with HL or NHL between January 1970 and July 2001 was identified using the Sheffield Lymphoma Group database. A search was undertaken for all patients diagnosed with a subsequent primary malignancy. Two matched controls were identified for each case. Odds ratios were calculated to detect and quantify any risk factors in the cases compared to their matched controls. Mean follow-up for the cohort was 5.2 years. A total of 68 patients who developed second cancers at least 6 months after their primary diagnosis were identified, giving a crude incidence of 1.89% overall: 3.21% among the patients treated for HL, 1.32% in those treated for NHL. Most common were bronchial, breast, colorectal and haematological malignancies. High stage at diagnosis almost reached statistical significance in the analysis of just the NHL patients (odds ratio=3.48; P=0.068) after adjustment for other factors. Treatment modality was not statistically significant in any analysis. High stage at diagnosis of NHL may be a risk factor for developing a second primary cancer