Influence of Annealing on Properties of Spray Deposited ZnO Thin Films

Zinc Oxide (ZnO) thin films were deposited on glass substrates via the spray pyrolysis technique. The films were subsequently annealed in ambient air from 300°C to 500°C. The morphology and structural properties of the thin films were studied by field emission scanning electron microscope (FESEM), atomic force microscopy (AFM), and X-ray diffractometry (XRD) techniques. Electrical resistivity of the thin films was measured using a data acquisition unit. The optical properties of the films were characterized by UV-vis spectroscopy and photoluminescence (PL) technique. X-ray diffraction data showed that the films were grown in the (002) direction with a hexagonal wurtzite structure. The average grain size ranged from 15 to 27 nm. Increasing annealing temperatures resulted in larger grain sizes and higher crystallinity, with the surface roughness of annealed films being more than twice if compared to unannealed film. The electrical resistivity of the films decreased with the increasing annealing temperature. The UV and visible band emissions were observed in the photoluminescence spectra, due to exciton and defect-related emissions, respectively. The transmission values of the films were as high as 90% within the visible range (400–700 nm)

Consolidation of calcium phosphate powder through microwave sintering / Natasha Ahmad Nawawi, Ramesh Singh and Tan Chou Yong

In the last 50 years, the major drawback of HA ceramic usage in clinical applications is its inherent brittleness and lower mechanical strength than those of cortical bone. This is turn calls for the development of dense nanostructured HA with the major concern is to enhance densification while limiting its grain growth. Hence, a promising way to obtain this could be a fabrication of fully dense nanostructured materials through sintering process. In this work, eggshell derived hydroxyapatite (HA-Es) powder has been prepared via solid state sintering and its sinterability was investigated through microwave sintering at various sintering temperatures (950-1250 °C). The phase stability, microstructural evolution and relative density of HA-Es were deliberated. The results indicate that microwave sintering regime has been successfully employed and this short sintering regime did not promote extensive grain growth even when sintered at high temperature

Sinteran hidroksiapatit dalam atmosfera nitrogen untuk peningkatan sifat mikrokekerasan

Hidroksiapatit (HA) adalah sejenis kalsium fosfat yang merupakan komposisi kepada kebanyakan fasa mineral tulang dan enamel gigi. HA bersifat bioserasi dan berkonduksi osteo selain mempunyai afiniti biologi dan kimia yang bagus untuk tisu tulang. Dengan ciri tersebut, HA diguna secara luas sebagai graf tulang dan bahan salut bagi implan tisu keras manusia. Walau bagaimanapun, kerapuhan dan keliatan patah yang rendah HA tersinter menghadkan penggunaannya dalam aplikasi bebanan yang tinggi. Kajian ini tertumpu kepada mengenal pasti kesan atmosfera sinteran dengan gas nitrogen (N2) ke atas sifat mekanik HA untuk aplikasi pergigian. Serbuk nano HA dicirikan dengan menggunakan mikroskop elektron pancaran. Cakera silinder HA dihasilkan dengan kaedah penekanan ekapaksi. Kemudian, cakera silinder HA dikenakan tekanan isostatik sejuk dan disinter dalam dua atmosfera sinteran yang berbeza iaitu sinteran dalam gas N2 dan sinteran dalam udara pada suhu 1300°C. Ketumpatan, mikrostruktur, kestabilan fasa dan mikrokekerasan HA tersinter dicirikan. Secara keseluruhan, sinteran dengan menggunakan gas N2 menyebabkan pertumbuhan saiz butiran yang lebih besar dengan ketumpatan relatif dan mikrokekerasan yang lebih tinggi jika dibandingkan dengan atmosfera sinteran dalam udara. Dalam kajian ini, HA yang disinter dengan menggunakan gas N2 pada suhu 1300°C menunjukkan mikrostruktur yang lebih tumpat, ketumpatan relatif (94%) dan mikrokekerasan (4.07 GPa) yang lebih tinggi jika berbanding dengan sinteran dalam udara tanpa penguraian HA. Kesimpulannya, penggunaan atmosfera sinteran dengan menggunakan gas N2 pada suhu 1300°C dapat meningkatkan sifat kekerasan Vickers nanokomposit HA dengan mikrostruktur yang padat

Sintering behavior of hydroxyapatite ceramics prepared by different routes

The sintering behaviour of three different HA, i.e. a commercial HA(C) and synthesized HA by wet precipitation, HA(W) and mechanochemical method, HA(M) were investigated over the temperature range of 1000°C to 1350°C. In the present research, a wet chemical precipitation reaction was successfully employed to synthesize highly crystalline, high purity and single phase stoichiometric HA powder that is highly sinteractive particularly at low temperatures below 1100°C. It has been revealed that the sinterability and mechanical properties of the synthesized HA by this method was significantly higher than that of the commercial material and HA which was synthesized by mechanomical method. The optimum sintering temperature for the synthesized HA(W) was 1100°C with the following properties being recorded: 99.8% relative density, Vickers hardness of 7.04 GPa and fracture toughness of 1.22 MPam½. In contrast, the optimum sintering temperature for the commercial HA(C) and synthesized HA(M) was 1300°C with relative density of 98% and 95.5%, Vickers hardness of 5.47 GPa and 4.73 GPa, fracture toughness of 0.75 MPam½ and 0.82 MPam½ being measured, respectively

Urban coral reefs: Degradation and resilience of hard coral assemblages in coastal cities of East and Southeast Asia

© 2018 The Author(s) Given predicted increases in urbanization in tropical and subtropical regions, understanding the processes shaping urban coral reefs may be essential for anticipating future conservation challenges. We used a case study approach to identify unifying patterns of urban coral reefs and clarify the effects of urbanization on hard coral assemblages. Data were compiled from 11 cities throughout East and Southeast Asia, with particular focus on Singapore, Jakarta, Hong Kong, and Naha (Okinawa). Our review highlights several key characteristics of urban coral reefs, including “reef compression” (a decline in bathymetric range with increasing turbidity and decreasing water clarity over time and relative to shore), dominance by domed coral growth forms and low reef complexity, variable city-specific inshore-offshore gradients, early declines in coral cover with recent fluctuating periods of acute impacts and rapid recovery, and colonization of urban infrastructure by hard corals. We present hypotheses for urban reef community dynamics and discuss potential of ecological engineering for corals in urban areas

Genome-Wide Survey and Developmental Expression Mapping of Zebrafish SET Domain-Containing Genes

SET domain-containing proteins represent an evolutionarily conserved family of epigenetic regulators, which are responsible for most histone lysine methylation. Since some of these genes have been revealed to be essential for embryonic development, we propose that the zebrafish, a vertebrate model organism possessing many advantages for developmental studies, can be utilized to study the biological functions of these genes and the related epigenetic mechanisms during early development. To this end, we have performed a genome-wide survey of zebrafish SET domain genes. 58 genes total have been identified. Although gene duplication events give rise to several lineage-specific paralogs, clear reciprocal orthologous relationship reveals high conservation between zebrafish and human SET domain genes. These data were further subject to an evolutionary analysis ranging from yeast to human, leading to the identification of putative clusters of orthologous groups (COGs) of this gene family. By means of whole-mount mRNA in situ hybridization strategy, we have also carried out a developmental expression mapping of these genes. A group of maternal SET domain genes, which are implicated in the programming of histone modification states in early development, have been identified and predicted to be responsible for all known sites of SET domain-mediated histone methylation. Furthermore, some genes show specific expression patterns in certain tissues at certain stages, suggesting the involvement of epigenetic mechanisms in the development of these systems. These results provide a global view of zebrafish SET domain histone methyltransferases in evolutionary and developmental dimensions and pave the way for using zebrafish to systematically study the roles of these genes during development

Вихретоковый анизотропный термоэлектрический первичный преобразователь лучистого потока

Представлена оригинальная конструкция первичного преобразователя лучистого потока, который может служить основой для создания приемника неселективного излучения с повышенной чувствительностью

The 5p15.33 Locus Is Associated with Risk of Lung Adenocarcinoma in Never-Smoking Females in Asia

Genome-wide association studies of lung cancer reported in populations of European background have identified three regions on chromosomes 5p15.33, 6p21.33, and 15q25 that have achieved genome-wide significance with p-values of 10−7 or lower. These studies have been performed primarily in cigarette smokers, raising the possibility that the observed associations could be related to tobacco use, lung carcinogenesis, or both. Since most women in Asia do not smoke, we conducted a genome-wide association study of lung adenocarcinoma in never-smoking females (584 cases, 585 controls) among Han Chinese in Taiwan and found that the most significant association was for rs2736100 on chromosome 5p15.33 (p = 1.30×10−11). This finding was independently replicated in seven studies from East Asia totaling 1,164 lung adenocarcinomas and 1,736 controls (p = 5.38×10−11). A pooled analysis achieved genome-wide significance for rs2736100. This SNP marker localizes to the CLPTM1L-TERT locus on chromosome 5p15.33 (p = 2.60×10−20, allelic risk = 1.54, 95% Confidence Interval (CI) 1.41–1.68). Risks for heterozygote and homozygote carriers of the minor allele were 1.62 (95% CI; 1.40–1.87), and 2.35 (95% CI: 1.95–2.83), respectively. In summary, our results show that genetic variation in the CLPTM1L-TERT locus of chromosome 5p15.33 is directly associated with the risk of lung cancer, most notably adenocarcinoma