bluuebunny/crossref_metadata_2025 huggingface dataset:
Granzyme Gis expressed in the two-cell stage mouse embryo and is required for the maternal-zygotic transition
Authors: Tsai Tung-Chou , Lin William , Yang Shang-Hsun , Cheng Winston TK , Cheng En-Hui , Lee Maw-Sheng , Chong Kowit-Yu , Chen Chuan-Mu
Published: August 2010

Background

Detailed knowledge of the molecular and cellular mechanisms that direct spatial and temporal gene expression in pre-implantation embryos is critical for understanding the control of the maternal-zygotic transition and cell differentiation in early embryonic development. In this study, twenty-three clones, expressed at different stages of early mouse development, were identified using differential display reverse transcription polymerase chain reaction (DDRT-PCR). One of these clones, which is expressed in 2-cell stage embryos at 48 hr post-hCG injection, shows a perfect sequence homology to the gene encoding the granzyme G protein. The granzyme family members are serine proteases that are present in the secretory granules of cytolytic T lymphocytes. However, the pattern of granzyme G expression and its function in early mouse embryos are entirely unknown.

Results

Upon the introduction of an antisense morpholino (2 mM) against granzyme G to knock-down endogenous gene function, all embryos were arrested at the 2- to 4-cell stages of egg cleavage, and thede novosynthesis of zygotic RNAs was decreased. The embryonic survival rate was dramatically decreased at the late 2-cell stage when serine protease-specific inhibitors, 0.1 mM 3,4-dichloroisocoumarin (3,4-DCI), and 2 mM phenyl methanesulphonyl fluoride (PMSF), were added to thein vitroembryonic culture medium. Survival was not affected by the addition of 0.5 mM EDTA, a metalloproteinase inhibitor.

Conclusion

We characterized for the first time the expression and function ofgranzyme Gduring early stage embryogenesis. Our data suggest that granzyme G is an important factor in early mouse embryonic development and may play a novel role in the elimination of maternal proteins and the triggering of zygotic gene expression during the maternal-zygotic transition.
An evolutionary analysis of cAMP-specific Phosphodiesterase 4 alternative splicing
Authors: Johnson Keven R , Nicodemus-Johnson Jessie , Danziger Robert S
Published: August 2010

Background

Cyclic nucleotide phosphodiesterases (PDEs) hydrolyze the intracellular second messengers: cyclic adenosine monophosphate (cAMP) and cyclic guanine monophosphate (cGMP). The cAMP-specific PDE family 4 (PDE4) is widely expressed in vertebrates. Each of the four PDE4 gene isoforms (PDE4 A-D) undergo extensive alternative splicing via alternative transcription initiation sites, producing unique amino termini and yielding multiple splice variant forms from each gene isoform termed long, short, super-short and truncated super-short. Many species across the vertebrate lineage contain multiple splice variants of each gene type, which are characterized by length and amino termini.

Results

A phylogenetic approach was used to visualize splice variant form genesis and identify conserved splice variants (genome conservation with EST support) across the vertebrate taxa. Bayesian and maximum likelihood phylogenetic inference indicated PDE4 gene duplication occurred at the base of the vertebrate lineage and reveals additional gene duplications specific to the teleost lineage. Phylogenetic inference and PDE4 splice variant presence, or absence as determined by EST screens, were further supported by the genomic analysis of select vertebrate taxa. Two conserved PDE4 long form splice variants were found in each of the PDE4A, PDE4B, and PDE4C genes, and eight conserved long forms from the PDE4 D gene. Conserved short and super-short splice variants were found from each of the PDE4A, PDE4B, and PDE4 D genes, while truncated super-short variants were found from the PDE4C and PDE4 D genes. PDE4 long form splice variants were found in all taxa sampled (invertebrate through mammals); short, super-short, and truncated super-short are detected primarily in tetrapods and mammals, indicating an increasing complexity in both alternative splicing and cAMP metabolism through vertebrate evolution.

Conclusions

There was a progressive independent incorporation of multiple PDE4 splice variant forms and amino termini, increasing PDE4 proteome complexity from primitive vertebrates to humans. While PDE4 gene isoform duplicates with limited alternative splicing were found in teleosts, an expansion of both PDE4 splice variant forms, and alternatively spliced amino termini predominantly occurs in mammals. Since amino termini have been linked to intracellular targeting of the PDE4 enzymes, the conservation of amino termini in PDE4 splice variants in evolution highlights the importance of compartmentalization of PDE4-mediated cAMP hydrolysis.
Genetic validation of whole-transcriptome sequencing for mapping expression affected by cis-regulatory variation
Authors: Babak Tomas , Garrett-Engele Philip , Armour Christopher D , Raymond Christopher K , Keller Mark P , Chen Ronghua , Rohl Carol A , Johnson Jason M , Attie Alan D , Fraser Hunter B , Schadt Eric E
Published: August 2010

Background

Identifying associations between genotypes and gene expression levels using microarrays has enabled systematic interrogation of regulatory variation underlying complex phenotypes. This approach has vast potential for functional characterization of disease states, but its prohibitive cost, given hundreds to thousands of individual samples from populations have to be genotyped and expression profiled, has limited its widespread application.

Results

Here we demonstrate that genomic regions with allele-specific expression (ASE) detected by sequencing cDNA are highly enriched for cis- acting expression quantitative trait loci (cis- eQTL) identified by profiling of 500 animals in parallel, with up to 90% agreement on the allele that is preferentially expressed. We also observed widespread noncoding and antisense ASE and identified several allele-specific alternative splicing variants.

Conclusion

Monitoring ASE by sequencing cDNA from as little as one sample is a practical alternative to expression genetics for mapping cis-acting variation that regulates RNA transcription and processing.
A case-control analysis of common variants in GIP with type 2 diabetes and related biochemical parameters in a South Indian population
Authors: Sugunan Divya , Nair Anup K , Kumar Harish , Gopalakrishnapillai Anilkumar
Published: August 2010

Background

Glucose-dependent insulinotropic polypeptide (GIP) is one of the incretins, which plays a crucial role in the secretion of insulin upon food stimulus and in the regulation of postprandial glucose level. It also exerts an effect on the synthesis and secretion of lipoprotein lipase, from adipocytes, important for lipid metabolism. The aim of our study was to do a case-control association analysis of common variants in GIP in association with type 2 diabetes and related biochemical parameters.

Method

A total of 2000 subjects which includes 1000 (584M/416F) cases with type 2 diabetes and 1000 (470M/530F) normoglycemic control subjects belonging to Dravidian ethnicity from South India were recruited to assess the effect of single nucleotide polymorphisms (SNPs) in GIP (rs2291725, rs2291726, rs937301) on type 2 diabetes in a case-control manner. The SNPs were genotyped by using tetra primer amplification refractory mutation system-PCR (ARMS PCR). For statistical analysis, our study population was divided into sub-groups based on gender (male and female). Association analysis was carried out using chi-squared test and the comparison of biochemical parameters among the three genotypes were performed using analysis of covariance (ANCOVA).

Result

Initial analysis revealed that, out of the total three SNPs selected for the present study, two SNPs namely rs2291726 and rs937301 were in complete linkage disequilibrium (LD) with each other. Therefore, only two SNPs, rs2291725 and rs2291726, were genotyped for the association studies. No significant difference in the allele frequency and genotype distribution of any of the SNPs in GIP were observed between cases and controls (P > 0.05). Analysis of biochemical parameters among the three genotypes showed a significant association of total cholesterol (P = 0.042) and low density lipoprotein (LDL) with the G allele of the SNP rs2291726 in GIP (P = 0.004), but this was observed only in the case of female subjects. However this association does not remain significant after correction for multiple testing by Bonferroni's inequality method.

Conclusion

No statistically significant association was observed between any of the SNPs analysed and type 2 diabetes in our population. But the analysis of biochemical parameters indicates that the G allele in rs2291726 may be a putative risk allele for increased LDL cholesterol and further studies in other population needs to be carried out for ascertaining its role in cholesterol metabolism and subsequent cardiovascular risk.
Human Sulfatase 2 inhibits in vivo tumor growth of MDA-MB-231 human breast cancer xenografts
Authors: Peterson Sarah M , Iskenderian Andrea , Cook Lynette , Romashko Alla , Tobin Kristen , Jones Michael , Norton Angela , Gómez-Yafal Alicia , Heartlein Michael W , Concino Michael F , Liaw Lucy , Martini Paolo GV
Published: August 2010

Background

Extracellular human sulfatases modulate growth factor signaling by alteration of the heparin/heparan sulfate proteoglycan (HSPG) 6-O-sulfation state. HSPGs bind to numerous growth factor ligands including fibroblast growth factors (FGF), epidermal growth factors (EGF), and vascular endothelial growth factors (VEGF), and are critically important in the context of cancer cell growth, invasion, and metastasis. We hypothesized that sulfatase activity in the tumor microenvironment would regulate tumor growth in vivo.

Methods

We established a model of stable expression of sulfatases in the human breast cancer cell line MDA-MB-231 and purified recombinant human Sulfatase 2 (rhSulf2) for exogenous administration. In vitro studies were performed to measure effects on breast cancer cell invasion and proliferation, and groups were statistically compared using Student's t-test. The effects of hSulf2 on tumor progression were tested using in vivo xenografts with two methods. First, MDA-MB-231 cells stably expressing hSulf1, hSulf2, or both hSulf1/hSulf2 were grown as xenografts and the resulting tumor growth and vascularization was compared to controls. Secondly, wild type MDA-MB-231 xenografts were treated by short-term intratumoral injection with rhSulf2 or vehicle during tumor growth. Ultrasound analysis was also used to complement caliper measurement to monitor tumor growth. In vivo studies were statistically analyzed using Student's t test.

Results

In vitro, stable expression of hSulf2 or administration of rhSulf2 in breast cancer cells decreased cell proliferation and invasion, corresponding to an inhibition of ERK activation. Stable expression of the sulfatases in xenografts significantly suppressed tumor growth, with complete regression of tumors expressing both hSulf1 and hSulf2 and significantly smaller tumor volumes in groups expressing hSulf1 or hSulf2 compared to control xenografts. Despite significant suppression of tumor volume, sulfatases did not affect vascular density within the tumors. By contrast, transient exogenous treatment of MDA-MB-231 xenografts with rhSulf2 was not sufficient to inhibit or reverse tumor growth.

Conclusion

These data indicate that in vivo progression of human breast cancer xenografts can be inhibited with sulfatase expression, and therapeutic effect requires constant delivery at the tumor site. Our results support a direct effect of sulfatases on tumor growth or invasion, rather than an effect in the stromal compartment.
Asháninka medicinal plants: a case study from the native community of Bajo Quimiriki, Junín, Peru
Authors: Luziatelli Gaia , Sørensen Marten , Theilade Ida , Mølgaard Per
Published: August 2010

Background

The Asháninka Native Community Bajo Quimiriki, District Pichanaki, Junín, Peru, is located only 4 km from a larger urban area and is dissected by a major road. Therefore the loss of traditional knowledge is a main concern of the local headman and inhabitants. The present study assesses the state of traditional medicinal plant knowledge in the community and compares the local pharmacopoeia with the one from a related ethnic group.

Methods

Fieldwork was conducted between July and September 2007. Data were collected through semi-structured interviews, collection of medicinal plants in the homegardens, forest walks, a walk along the river banks, participant observation, informal conversation, cross check through voucher specimens and a focus group interview with children.

Results

Four-hundred and two medicinal plants, mainly herbs, were indicated by the informants. The most important families in terms of taxa were Asteraceae, Araceae, Rubiaceae, Euphorbiaceae, Solanaceae and Piperaceae. Eighty-four percent of the medicinal plants were wild and 63% were collected from the forest. Exotics accounted to only 2% of the medicinal plants. Problems related to the dermal system, digestive system, and cultural belief system represented 57% of all the medicinal applications. Some traditional healers received non-indigenous customers, using their knowledge as a source of income. Age and gender were significantly correlated to medicinal plant knowledge. Children knew the medicinal plants almost exclusively by their Spanish names. Sixteen percent of the medicinal plants found in this community were also reported among the Yanesha of the Pasco Region.

Conclusions

Despite the vicinity to a city, knowledge on medicinal plants and cultural beliefs are still abundant in this Asháninka Native Community and the medicinal plants are still available in the surroundings. Nevertheless, the use of Spanish names for the medicinal plants and the shift of healing practices towards a source of income with mainly non-indigenous customers, are signs of acculturation. Future studies on quantification of the use of medicinal plants, dynamics of transmission of ethno-medicinal knowledge to the young generations and comparison with available pharmacological data on the most promising medicinal plants are suggested.
Aplastic anemia associated with interferon alpha 2a in a patient with chronic hepatitis C virus infection: a case report
Authors: Ioannou Savvas , Hatzis Gregorios , Vlahadami Ioanna , Voulgarelis Michael
Published: August 2010

Introduction

Hepatitis-associated aplastic anemia is a common syndrome in patients with bone marrow failure. However, hepatitis-associated aplastic anemia is an immune-mediated disease that does not appear to be caused by any of the known hepatitis viruses including hepatitis C virus. In addition, to the best of our knowledge there are no reported cases of patients with chronic hepatitis C virus infection developing aplastic anemia associated with pegylated interferon alpha 2a treatment.

Case presentation

We report the case of a 46-year-old Greek man who developed severe aplastic anemia during treatment with pegylated interferon alpha 2a for chronic hepatitis C virus infection. He presented with generalized purpura and bruising, as well as pallor of the skin and mucous membranes. His blood tests showed pancytopenia. He underwent allogeneic bone marrow transplantation after completing two courses of immunosuppressive therapy with antithymocyte globulin and cyclosporin A.

Conclusions

The combination of a specific environmental precipitant represented by the hepatitis C virus infection, an altered metabolic detoxification pathway due to treatment with pegylated interferon alpha 2a and a facilitating genetic background such as polymorphism in metabolic detoxification pathways and specific human leukocyte antigen genes possibly conspired synergistically in the development of aplastic anemia in this patient. Our case clearly shows that the causative role of pegylated interferon alpha 2a in the development of aplastic anemia must not be ignored.
Defining the Epigenetic Actions of Growth Hormone: Acute Chromatin Changes Accompany GH-Activated Gene Transcription
Authors: Chia Dennis J. , Rotwein Peter
Published: August 2010

Many of the long-term physiological effects of GH require hormone-mediated changes in gene expression. The transcription factor signal transducer and activator of transcription 5b (Stat5b) plays a critical role in the actions of GH on growth and metabolism by regulating a large number of GH-dependent genes by incompletely understood mechanisms. Here we have assessed the impact of GH-initiated and Stat5b-mediated signaling on the chromatin landscape of hormone-regulated genes in the liver of pituitary-deficient young adult male rats. In the absence of GH there was minimal ongoing transcription at the Socs2, Cish, Igfals, and Spi 2.1 promoters, minimal occupancy of Stat5b at proximal promoter sites, and relatively closed chromatin, as evidenced by low levels of core histone acetylation. In contrast, transcriptionally silent Igf1 promoter 1 appeared poised to be activated, based on binding of coactivators p300 and Med1/Trap220, high levels of histone acetylation, and the presence of RNA polymerase II. GH treatment led to a 8- to 20-fold rise in transcriptional activity of all five genes within 30–60 min and was accompanied by binding of Stat5b to the proximal Socs2, Cish, Igfals, and Spi 2.1 promoters and to seven distal Igf1 Stat5b elements, by enhanced histone acetylation at all five promoters, by recruitment of RNA polymerase II to the Socs2, Cish, Igfals, and Spi 2.1 promoters, and by loss of the transcriptional repressor Bcl6 from Socs2, Cish, and Igfals Stat5b sites, but not from two Igf1 Stat5b domains. We conclude that GH actions induce rapid and dramatic changes in hepatic chromatin at target promoters and propose that the chromatin signature of Igf1 differs from other GH-and Stat5b-dependent genes.
Commentary—Do Bids Equal Values on eBay?
Authors: Hortaçsu Ali , Nielsen Eric R.
Published: August 2010

We argue that the Zeithammer and Adams paper [Zeithammer, R., C. Adams. 2010. The sealed-bid abstraction in online auctions. Marketing Sci. 29(6) 964–987] successfully documents consistent patterns in eBay bidding data that cast doubt on the common assumption that bidders in such auctions follow a “bid = value” strategy. These anomalies lend support to the authors' alternative model in which some bidders bid reactively and consequently bid below their valuation most of the time. The consistency of the authors' findings as well as the ability of their alternative explanation to account for all of their test results lends great support to their thesis. However, we think that several of their empirical tests examine ancillary assumptions about bidder behavior and do not test the bid = value assumption directly. Furthermore, although their reduced-form model incorporating “reactive” bidders is a good first attempt at expanding the canonical framework, we worry that their counterfactual pricing analysis using the reactive model is suspect because the parameters they estimate are not structural. Overall, the Zeithammer and Adams paper is a carefully argued critique of empirical methods used to study online auctions and provides valuable ideas to improve on these methods.
ThalassoChip, an array mutation and single nucleotide polymorphism detection tool for the diagnosis of β-thalassaemia
Authors: Shammas Christos , Papasavva Thessalia , Felekis Xenia , Christophorou Christos , Roomere Hanno , Synodinos Jan Traeger , Kanavakis Emmanuel , El-Khateeb Mohammed , Hamamy Hanan , Mahmoud Tamara , Shboul Mohammad , Beshlawy Amal El , Filon Dvora , Hussein Ibtessam R. , Galanello Renzo , Romeo Giovanni , Kleanthous Marina
Published: August 2010

Background: The detection and diagnosis of β-thalassaemia for populations with molecular heterogeneity, or diverse ethnic groups, has increased the need for the development of an array high-throughput diagnostic tool that can deliver large scale genetic detection. We report on the update and validation of the ThalassoChip, a β-thalassaemia genetic diagnostic tool which is based on arrayed primer extension (APEX) technology.

Methods: ThalassoChip slides with new and redesigned probes were prepared for testing the microarray. Six hundred and sixty DNA samples collected from eight Mediterranean countries were used for standardisation, optimisation and validation of the ThalassoChip. The β-globin gene region was amplified by PCR, the products were hybridised to the probes after fragmentation and the APEX reaction followed.

Results: The ThalassoChip was updated with new probes and now has the ability to detect 57 β-globin gene mutations and three single nucleotide polymorphisms (SNPs) in a single test. The ThalassoChip as well as the PCR and APEX reactions were standardised and optimised using 500 DNA samples that were previously genotyped using conventional diagnostic techniques. Some probes were redesigned in order to improve the specificity and sensitivity of the test. Validation of the ThalassoChip performed using 160 samples analysed in blinded fashion showed no error.

Conclusions: The updated version of the ThalassoChip is versatile, robust, cost-effective and easily adaptable, but most notably can provide comprehensive genetic diagnosis for β-thalassaemia and other haemoglobinopathies.

Clin Chem Lab Med 2010;48:1713–8.
Thermal stability of magnetite (Fe3O4) nanoparticles
Authors: Ong B.H. , Devaraj N. K. , Matsumoto M. , Abdullah M. H.
Published: August 2010

Magnetite (Fe3O4) nanoparticles are prime candidates for biomedical applications due to their biocompatibility and good magnetic properties. However, magnetite is highly susceptible to oxidation when exposed to the atmosphere. In order to preserve their properties, it is important for the particles to maintain their magnetite phase. In this study, magnetite nanoparticles were prepared using the conventional co3precipitation of ferrous (Fe2+) and ferric (Fe3+) chloride salt solutions with sodium hydroxide (NaOH). Thermogravimetric analysis (TGA) was subsequently carried out to identify the transition temperatures. Energy Dispersive X3Ray (EDX) spectrum shows the presence of impurities, such as sodium (Na) and chloride (Cl) ions in the as3synthesized magnetite nanoparticles. The as3synthesized samples were then calcined in a chamber furnace according to TGA data. The calcined samples were next characterised by X3ray Powder Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM) to determine the changes in phase and magnetic properties of the nanoparticles as a function of different calcination temperatures.
Magnetic and Transport Properties of Ni Doped Pr0.5Ca0.5Mn1-xNixO3-δ
Authors: Damari L. , Pelleg J. , Gorodetsky G. , Korn C. , Markovich V. , Shames A. , Wu X. , Mogilyansky D. , Fita I.
Published: August 2010

Structural, magnetic and transport properties of Pr0.5Ca0.5Mn1-xNixO3 (x =0, 0.04, 0.07, 0.1) series have been investigated. The substitution of Mn ions by Ni induces drastic changes in the magneto-transport properties of Pr0.5Ca0.5MnO3. The physical behavior depends drastically on O stoichiometry. For the low Ni doping x=0.04, 0.07, spin glass configuration is rather favored than ferromagnetism; while for x=0.10, the ferromagnetic phase is significantly suppressed. Pronounced irreversibility between zero-field cooled (ZFC) and field cooled (FC) magnetization and a kink in the ZFC curve observed for x=0.04 and 0.07 are indicative of spin-glass-like state. Applied hydrostatic pressure of about 10 kbar reduces the temperature of charge ordering in an x=0 sample by about 10 K indicating a pressure induced suppression of the Jahn-Teller distortions and of the electron-phonon coupling. Electron magnetic resonance (EMR) unambiguously evidences appearance of FM phase in Ni doped manganites. Temperature dependence of EMR spectra parameters allow us to speculate on the effect of magnetic inhomogeneities.
Fluorite and Pyrochlore Phases in the HfO2 -La2O3 -Gd2O3 Systems: Characterization and Calorimetric Study of Samples Quenched From Melts Formed by Laser Heating and Aerodynamic Levitation
Authors: Ushakov Sergey V. , Navrotsky Alexandra , Tangeman Jean A.
Published: August 2010

New experimental results on pyrochlore and defect fluorite phases in HfO2-La2O3 and HfO2-Gd2O3 systems are summarized. Fluorite Hf0.5Gd0.5O1.75 was formed by containerless melting and quenching. Melts with 25-65 mol% La2O3 did not produce any fluorite-type phases, but pyrochlores with cell parameters 10.74 to 10.86 Å. The fluorite phase of Hf0.5La0.5O1.75 can be formed on crystallization of an amorphous precursor from aqueous precipitation. Both La- and Gd- fluorite phases transform to ordered pyrochlore on annealing at 1450 °C. The enthalpies of formation from oxides are −107 ±5 kJ/mol for Hf2La2O7 and −49 ±5 kJ/mol for Hf2Gd2O7 as measured by high-temperature solution calorimetry. Further experiments are needed to elucidate the nature of stabilization of fluorite phase in thin films and powders. Occurrence of disordered phases in thin films, nanoparticles and radiation damaged materials is discussed.
Study of defects and structural transformations induced by ion irradiation of Y2O3 thin films deposited by Ion Beam Sputtering
Authors: Lacroix Bertrand , Paumier Fabien , Jublot Michael , Pacaud Jérôme , Gaboriaud Rolly J.
Published: August 2010

Y2O3 thin films deposited by Ion Beam Sputtering (IBS) deposition technique exhibit a particular disordered microstructure. In order to obtain a better knowledge on phase transition mechanisms occurring during irradiation, thin films with different microstructures have been implanted with xenon ions at different energies and different doses. This work established two types of transition (cubic-amorphous or cubic-monoclinic) depending mainly on the ion energy with a possibility to control the damaging kinetic via the pre-existing oxygen disorder.
Effects of Ion Irradiation on the Microstructure of an ODS/Fe12Cr Alloy
Authors: Castro V. de , Lozano-Perez S. , Jenkins M. L.
Published: August 2010

This study describes the microstructures of an ODS/Fe12Cr alloy before and after Fe+ irradiation at 500°C to a dose of 2.5 dpa and compares these microstructures with those of a reference Fe12Cr alloy produced following the same pulvimetallurgical route. The grain and dislocation structures of the alloys did not seem to change after irradiation. The main difference after irradiation was the appearance of small loops, which had similar sizes, distribution and densities in the ODS and reference alloys. The size distributions and chemical compositions of the ODS particles were similar to those found before irradiation.
Effect of growth rate on microstructure and microstructure evolution of directionally solidified Nb-Si alloys
Authors: Sekito Yoshihito , Miura Seiji , Ohkubo Kenji , Mohri Tetsuo , Sakaguchi Norihito , Watanabe Seiichi , Kimura Yoshisato , Mishima Yoshinao
Published: August 2010

In the present work, Nb-18.1Si-1.5Zr alloy rods are produced with a growth rate ranging from 1.5 to about 1500 mm/h using the optical floating zone (OFZ) furnace. A part of each specimen is heat-treated at 1650 oC for 100 h. The microstructure was observed using SEM and TEM and analyzed using EPMA and EBSD.

Eutectic-cells are observed in as-grown specimens with a growth rate of 150 mm/h or higher. It is found by EBSD analysis that the solidification direction of Nb is along <113> and that of Nb3Si is along <001], and {112} of Nb and {110) of Nb3Si are parallel. The present crystallographic orientation relationship between Nb and Nb3Si is different from that found in previous reports by several researchers. It was also confirmed that the heat-treated microstructure in the specimen grown by OFZ with a growth rate of 150 mm/h is similar to that in the heattreated specimen prepared by arc-melting.
Erbium Alloyed Aluminum Nitride Films for Piezoelectric Applications
Authors: Kabulski A. , Pagán V. R. , Korakakis D
Published: August 2010

Aluminum nitride (AlN) films have been explored for sensor and actuator applications, but the resultant piezoelectric coefficient is still too low to make the films more competitive with more commonly used piezoelectric materials such as lead zirconate titanate (PZT). While AlN does have the disadvantage of a lower piezoelectric response, it does have the ability to maintain its piezoelectric properties above 400°C, something that is not possible with other piezoelectric materials. It is desirable to achieve a larger piezoelectric response for AlN in order to facilitate the integration of nitride based devices into existing technologies but conventional methods of improving the response by growing higher quality film only result in slight improvements in the piezoelectric response. A method of improving the d33 piezoelectric coefficient beyond any values found in literature may be possible by exploring methods of improving PZT films.

Rare earth doping has been reported to improve the piezoelectric properties of PZT resulting in significant increases in the piezoelectric coefficient. Research has been conducted using rare earth dopants to improve upon the optical properties of AlN, but the impact on piezoelectric effect has never been considered.

Thin, 250-1000 nm, AlN:Er films have been reactively sputtered using erbium (Er)/aluminum alloyed targets to explore any improvement in piezoelectric properties of the AlN:Er films as compared to AlN films. AlN films with 0.5 and 1.5% Er concentrations have been found to have piezoelectric coefficients that are larger than comparable ‘Er-free’ AlN films. AlN films with only 0.5% Er quantities were found to increase the d33 coefficient compared to a similar AlN film depending on the thickness of the film. This increase results in d33,f values greater than 7pm/V which is larger than most values found in literature. By increasing the Er content to 1.5%, values of d33,f were found to be as large as 15 pm/V. This enhanced piezoelectric response is still lower than that of PZT, but can be used to create superior actuator devices than that of typical AlN films.
Ferroelectric Random Access Memory as a Non-Volatile Cache Solution in a Multimedia Storage System
Authors: Jung Dong Jin , Kim Kinam
Published: August 2010

We demonstrate that ferroelectric memory is very eligible to become a non-volatile cache solution, in particular, in a multimedia storage system such as solid-state disk. It could provide benefits both of performance and of reliability. In performance, a FRAM cache allows us to rid overhead of power-off recovery. Random WRITE performance has been improved by 250%. In assertion of endurance, we investigate acceleration factors to evaluate cycle-to-failure of the ferroelectric memory both in device-level and in capacitor-level. What has been found is that ferroelectric memory cells have 6.0×1014 of the cycle-to-failure at the operational condition of 85 o C and 2.0V. This cycle-to-failure is well above lifetime READ/WRITE cycles of 9.5×1013 in such system. From 2-dimensional stress simulation, it has also been concluded that the number of dummy cells plays a critical role in qualifying the high temperature life tests.
Piezoelectric Response of Lanthanum Doped Lead Zirconate Titanate Films for Micro Actuators Application
Authors: Iijima Takashi , Lee Bong-Yeon , Fukuyama Seiji
Published: August 2010

La doped lead zirconate titanate (PLZT) films are prepared using a chemical solution deposition process. The effect of La substitution on the piezoelectric response was investigated to clear the possibility of the micro actuator application for the PLZT films. Nominal compositions of the 10% Pb excess PLZT precursor solutions were controlled like La/Zr/Ti= 0/65/35, 3/65/35, 6/65/35, and 9/65/35. These precursor solutions were deposited on the Ir/Ti/SiO2/Si substrates, and the thickness of the PLZT films was 2μm. 10 to 20- μm- diameter Pt top electrodes are formed with a sputtering and a photolithography process. The polarization- field (P-E) hysteresis curves and the longitudinal displacement curves were measured with a twin beam laser interferometer connected with a ferroelectric test system. With increasing La substitution amount, theP-Ehysteresis curves became slim shape, and remnant polarization (Pr) decreased. The hysteresis of the piezoelectric longitudinal displacement curves also decreased with increasing La substitution amount. The amount of the displacement under unipolar electric field showed a peak at La/Zr/Ti= 3/65/35. The calculated effective longitudinal piezoelectric constant (d33eff) is 129.2 pm/V at 3/65/35. This amount was relatively higher than that of PZT films at morphotropic phase boundary (MPB: 0/53/47) composition prepared the same film preparation process.
Potential of Hot Wire CVD for Active Matrix TFT Manufacturing
Authors: Schropp Ruud E.I. , Houweling Zomer Silvester , Verlaan Vasco
Published: August 2010

Hot Wire Chemical Vapor Deposition (HWCVD) is a fast deposition technique with high potential for homogeneous deposition of thin films on large area panels or on continuously moving substrates in an in-line manufacturing system. As there are no high-frequency electromagnetic fields, scaling up is not hampered by finite wavelength effects or the requirement to avoid inhomogeneous electrical fields. Since 1996 we have been investigating the application of the HWCVD process for thin film transistor manufacturing. It already appeared then that these Thin Film Transistors (TFTs) were electronically far more stable than those with Plasma Enhanced (PE) CVD amorphous silicon. Recently, we demonstrated that very compact SiNx layers can be deposited at high deposition rates, up to 7 nm/s. The utilization of source gases in HWCVD of a-Si3N4 films deposited at 3 nm/s is 75 % and 7 % for SiH4 and NH3, respectively. Thin films of stoichiometric a-Si3N4 deposited at this rate have a high mass-density of 3.0 g/cm3. The dielectric properties have been evaluated further in order to establish their suitability for incorporation in TFTs. Now that all TFT layers, namely, the SiNx insulator, the a-Si:H or μc Si:H layers, and the n-type doped thin film silicon can easily be manufactured by HWCVD, the prospect of “all HWCVD” TFTs for active matrix production is within reach. We tested the 3 nm/s SiNx material combined with our protocrystalline Si:H layers deposited at 1 nm/s in ‘all HW’ TFTs. Results show that the TFTs are state of the art with a field-effect mobility of 0.4 cm2/Vs. In order to assess the feasibility of large area deposition we are investigating in-line HWCVD for displays and solar cells.
Correlation Between On/Off Ratio and Electron Traps in Hole-Only Carbon-Nanotube-Enabled Vertical Field Effect Transistors
Authors: McCarthy Mitchell Austin , Liu Bo , Rinzler Andrew Gabriel
Published: August 2010

Single wall carbon nanotube enabled vertical field effect transistors (VFETs) are studied and the dependence of the on/off ratio on the relative number of electron traps is investigated. Current versus voltage measurements on several VFETs with varying interfacial trap densities in the vicinity of the nanotube network/polymer active layer junction are taken. It is found that the on/off ratio of the VFET changes from 1600 to 20 for typical operational currents as the onset gate voltage in the off-to-on transfer curve shifts from 94 V to 72 V. Such a strong dependence on trapped charge motivates future work to uncover the mechanism of charge trapping.
Formation and Electrical Interfacing of Nanocrystal-Molecule Nanostructures
Authors: Barrett Claire , Lévêque Gaëtan , Doyle Hugh , Lydon Donocadh P , Redmond Gareth , Spalding Trevor R , Quinn Aidan J
Published: August 2010

The formation of nanocrystal-molecule-nanocrystal nanostructures via controlled mixing of Au nanocrystals and bifunctional Re linkers is reported. UV-visible absorbance data, coupled with histogram analysis of nanostructures measured using Scanning Electron Microscopy has shown a characteristic optical response at wavelengths close to 600 nm following formation of dimer and trimer nanostructures. Directed assembly processes based on dielectrophoretic trapping have also been developed for electrical interfacing of these nanostructures between top-down nanoelectrode pairs for electrical characterization.
Application of UV Irradiation in Removal of Post-etch 193 nm Photoresist
Authors: Le Quoc Toan , Kesters Els , Prager L , Lux Marcel , Marsik P , Vereecke Guy
Published: August 2010

This study focused on the effect of UV irradiation on modification of polymethyl methacrylate-based photoresist, and then on wet photoresist (PR) removal of patterned structure (single damascene structure). Three single-wavelength UV sources were considered for PR treatment, with λ = 172, 222, and 283 nm. Modification of blanket PR was characterized using Fourier-transform infrared spectroscopy (FTIR; chemical change), spectroscopic ellipsometry (SE; thickness change), and dissolution in organic solvent (solubility change). While for patterned samples, scanning electron microscopy (SEM) was used for evaluation of cleaning efficiency. In comparison to 172 nm, the PR film irradiated by 222 nm and 283 nm photons resulted in formation of higher concentration in C=C bond. Immersion tests using pure N-methyl pyrrolidone (NMP) at 60 °C for 2 min showed that some improvement in PR removal was only observed for PR films treated by 283 nm UV for short irradiation times. Irradiation by photons at the other two wavelengths did not result in an enhancement of removal efficiency.

The PR film treated by 222 nm photons was chosen for further study with O3/H2O vapor at 90°C. Experimental results showed a complete PR and BARC removal for UV-treated PR, which can be explained by C=C bond cleavage by the oxidizer.
VSS-induced NiSi2 Nanocrystal Memory
Authors: Li Bei , Liu Jianlin
Published: August 2010

NiSi2 nanocrystals were synthesized and used as the floating gate for nonvolatile memory application. Vapor-solid-solid mechanism was employed to grow the NiSi2 nanocrystals by introducing SiH4 onto the Ni catalysts-covered SiO2/Si substrate at 600°C. The average size and density of the NiSi2 nanocrystals are 7∼10nm and 3×1011 cm-2, respectively. Metal-oxide-semiconductor field-effect-transistor memory with NiSi2 nanocrystals was fabricated and characterized. Programming/erasing, retention and endurance measurements were carried out and good performances were demonstrated.
Development of Novel Multiferroic Composites Based on BaTiO3 and Hexagonal Ferrites
Authors: Karpinsky D. V. , Selezneva E. K. , Bdikin Igor , Figueiras F. , Kamentsev K. E. , Fetisov Yuri , Pullar R. C. , Krebbs J. , Alford N. M. , Kholkin A. L.
Published: August 2010

A new multiferroic composite ceramics with the general formula (x)Ba(Sr)Fe12O19-(1-x)BaTiO3 (x=0.1, 0.5) was synthesized via a simple solid-state reaction technique. Crystal structure analysis performed for both materials revealed the presence of two crystalline phases pertinent to the initial composite components. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to testify the crystallinity, microstructure, and local magnetoelectric interactions between ferroelectric and ferromagnetic grains. Magnetic measurements revealed that the saturation magnetization is proportional to the volume fraction of ferrite phase. Dielectric studies demonstrated strong frequency relaxation due to space charge polarization and high conductivity loss making macroscopic magnetoelectric measurements difficult. Novel nanoscale magnetoelectric effect observed by AFM is discussed.
Sharp Absorption and High Temperature Thermal Emission from Simple Metallic Photonic Crystals
Authors: Biswas Rana , Zhou Dayu , Puscasu Irina , Johnson Edward , Taylor Andrew , Zhao Weijun
Published: August 2010

We design and fabricate metallic photonic crystals with sharp absorption peaks in the infrared regime. We have fabricated a metallic photonic crystal consisting of a triangular lattice of holes in a silicon layer conformally coated with gold at a lattice pitch of 3.8 microns. Conventional lithographic and deep reactive ion etching was used. The photonic crystal exhibits a deep reflection minimum and sharp thermal emission peak near the lattice spacing. Measurements agree well with rigorous scattering matrix simulations. This simple single-layer structure with a single patterned exposure has no emission sidebands and can be scaled to other lattice spacings.
Impurity Study of Optical Properties in Fluorine-Doped Tin Oxide for Thin-Film Solar Cells
Authors: Li Xiaonan
Published: August 2010

Tin oxide (SnO2) is a durable, inexpensive transparent conducting oxide (TCO) material used for thin-film photovoltaic devices. However, the optical properties of conducting SnO2:F are generally not as good as in other conducting TCO materials such as ITO and ZnO:Al. Our previous analyses indicate that for thin-film solar cells, improving the optical properties of SnO2-coated glass could enhance photon collection and gain up to 10% additional photocurrent. Previously, we showed that some commercial SnO2 samples could have much higher optical absorption than others [2]. In this work, we continue our study on causes that could contribute to the high optical absorption of SnO2 films. The SnO2:F samples are fabricated by low-pressure metal-organic chemical vapor deposition or atmospheric-pressure chemical vapor deposition with tin precursors that includes different amounts of chlorine. Optical, electrical, and compositional analyses were performed. In addition to the free-carrier-introduced optical absorption, the non-active dopant also impacts the optical absorption. Among the SnO2 films fabricated with different precursors, the optical properties show a relationship based on the level of chlorine in the precursors and films. With a low-optical-absorption SnO2 layer, the solar cell could have better photon collection and a higher short-circuit current density.
Long-Term performance of a commercial Thermoelectric Power Generator
Authors: Hatzikraniotis Euripides , Zorbas Konstantinos , Kyratsi Theodora , Paraskevopoulos Konstantinos M
Published: August 2010

In this work, thermoelectric device was made, using a commercially available ThermoElectric Generator (TEG), in order to measure the gained power and efficiency for long-term performance. The module was subjected to sequential hot side heating at 200°C (392 0F), and cooling for 6000 cycles, in order to measure the TEG's power and EMF change. A 14% increase in the TEG’s material resistance was found, as well as a 5% reduction in the Seebeck coefficient. After the experiment, the module was disassembled and thermoelectric p- and n- legs were examined using IR spectroscopy.
InGaP Layers Grown on Different GaAs Surfaces for High Efficiency Solar Cells
Authors: Martínez Oscar , Hortelano Vanesa , Parra Vicente , Jimenez Juan , Prutskij Tatiana , Pelosi Claudio
Published: August 2010

InGaP layers grown on non-polar and polar GaAs substrate faces are investigated by Raman spectroscopy, microphotoluminescence and cathodoluminescence. The growth on polar faces benefits disorder respect to the layers grown on non polar (001) faces. It is shown that both (111)Ga and (111)As faces result in disordered InGaP layers. However, the layers grown on (111)As faces present inhomogeneous composition. The layers grown on (111)Ga faces present homogeneous composition close to lattice matching and are almost disordered.
Structural, Optical and Luminescent Properties of ZnO:Eu3+ Nanocrystals Prepared by Modified Sol-Gel Method
Authors: Jauregui-Rosas Segundo R. , Perales-Perez Oscar , Tomar M. S. , Jia Wei-Ji , Vasquez O. , Angelats-Silva Luis
Published: August 2010

Highly monodisperse ZnO:Eu3+ nanocrystals have been synthesized by modified sol-gel method from ethanolic solutions. The effect of Eu3+ ions (x=0.05-0.30) concentration on the structural, optical and luminescent properties has been evaluated. No other than the ZnO-wurtzite phase was observed at all dopant levels, which was confirmed by FT-IR and Raman spectroscopy techniques. A blue shift of the exciton peak and the increase on the corresponding band gap were observed at increasing Europium contents, which would indicate an interaction between Eu3+ ions and the development of the ZnO host structure. The luminescence properties were also dependent on Europium contents; a systematic blue shift and enhancement of the intensity of visible luminescence peak, attributed to an increment of surface defects, was observed by a rising Europium concentration. The red luminescence band, representing the 5D0→7F0 transition, was clearly observed in nanocrystals after annealing at 300OC for one hour. The presence of this band could be considered as an evidence of the effective energy transfer from ZnO to Eu3+ ions.
Improving the Near-Field Transmission Efficiency of Nano-Optical Transducers by Tailoring the Near-Field Sample
Authors: Sendur Kursat , Challener William
Published: August 2010

Despite research efforts to find a better nano-optical transducer for light localization and high transmission efficiency for existing and emerging plasmonic applications, there has not been much consideration on improving the near-field optical performance of the system by engineering the near-field sample. In this work, we demonstrate the impact of tailoring the near-field sample by studying an emerging plasmonic application, namely heat-assisted magnetic recording. Basic principles of Maxwell's and heat transfer equations are utilized to obtain a magnetic medium with superior optical and thermal performance compared to a conventional magnetic medium.
Near-Field Radiation from Nano-Particles and Nano-Antennas Illuminated with a Focused Beam of Light
Authors: Sendur Kursat , Sahinoz Ahmet , Unlu Eren , Yazici Serkan , Gulhan Mert
Published: August 2010

The interaction of photons with metallic nanoparticles and nanoantennas yields large enhancement and tight localization of electromagnetic fields in the vicinity of nanoparticles. In the first part of this study, the interaction of a spherical nanoparticle with focused beams of various angular spectra is investigated. This study demonstrates that the focused light can be utilized to manipulate the near-field radiation around nanoparticles. In the second part of this study, the interaction between linearly and radially polarized focused light with prolate spheroidal nanoparticles and nano-antennas is investigated. Strong and tightly localized longitudinal components of a radially polarized focused beam can excite strong plasmon modes on elongated nanoparticles such as prolate spheroids. The effect of a focused beam on parameters such as the numerical aperture of a beam and the wavelength of incident light, as well as particle geometry and composition are also studied.
The Structural Phase Transition in Individual Vanadium Dioxide Nanoparticles
Authors: Rivera Felipe , Davis Robert C. , Vanfleet Richard
Published: August 2010

Vanadium dioxide (VO2) single crystals undergo a structural first-order metal to insulator phase transition at approximately 68°C. This phase transition exhibits a resistivity change of up to 5 orders of magnitude in bulk specimens. We observe a 2-3 order of magnitude change in thin films of VO2. Individual particles with sizes ranging from 50 to 250 nm were studied by means of Transmission Electron Microscopy (TEM). The structural transition for individual particles was observed as a function of temperature. Furthermore, the interface between grains was also studied. We present our current progress in understanding this phase transition for polycrystalline thin films of VO2 from the view of individual particles.