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Sample records for a-to-i hyperediting substrates

  1. A Fluorescent Adenosine Analogue as a Substrate for an A-to-I RNA Editing Enzyme.

    PubMed

    Mizrahi, Rena A; Shin, Dongwon; Sinkeldam, Renatus W; Phelps, Kelly J; Fin, Andrea; Tantillo, Dean J; Tor, Yitzhak; Beal, Peter A

    2015-07-20

    Adenosine to inosine RNA editing catalyzed by ADAR enzymes is common in humans, and altered editing is associated with disease. Experiments using substrate RNAs with adenosine analogues at editing sites are useful for defining features of the ADAR reaction mechanism. The reactivity of ADAR2 was evaluated with RNA containing the emissive adenosine analogue thieno[3,4-d]-6-aminopyrimidine ((th)A). This nucleoside was incorporated into a mimic of the glutamate receptor B (GluR B) mRNA R/G editing site. We found that (th)A is recognized by AMV reverse transcriptase as A, and is deaminated rapidly by human ADAR2 to give (th)I. Importantly, ADAR reaction progress can be monitored by following the deamination-induced change in fluorescence of the (th)A-modified RNA. The observed high (th)A reactivity adds to our understanding of the structural features that are necessary for an efficient hADAR2 reaction. Furthermore, the new fluorescent assay is expected to accelerate mechanistic studies of ADARs.

  2. Dynamic hyper-editing underlies temperature adaptation in Drosophila

    PubMed Central

    Ashwal-Fluss, Reut; Pandey, Varun; Levanon, Erez Y.; Kadener, Sebastian

    2017-01-01

    In Drosophila, A-to-I editing is prevalent in the brain, and mutations in the editing enzyme ADAR correlate with specific behavioral defects. Here we demonstrate a role for ADAR in behavioral temperature adaptation in Drosophila. Although there is a higher level of editing at lower temperatures, at 29°C more sites are edited. These sites are less evolutionarily conserved, more disperse, less likely to be involved in secondary structures, and more likely to be located in exons. Interestingly, hypomorph mutants for ADAR display a weaker transcriptional response to temperature changes than wild-type flies and a highly abnormal behavioral response upon temperature increase. In sum, our data shows that ADAR is essential for proper temperature adaptation, a key behavior trait that is essential for survival of flies in the wild. Moreover, our results suggest a more general role of ADAR in regulating RNA secondary structures in vivo. PMID:28746393

  3. Dynamic hyper-editing underlies temperature adaptation in Drosophila.

    PubMed

    Buchumenski, Ilana; Bartok, Osnat; Ashwal-Fluss, Reut; Pandey, Varun; Porath, Hagit T; Levanon, Erez Y; Kadener, Sebastian

    2017-07-01

    In Drosophila, A-to-I editing is prevalent in the brain, and mutations in the editing enzyme ADAR correlate with specific behavioral defects. Here we demonstrate a role for ADAR in behavioral temperature adaptation in Drosophila. Although there is a higher level of editing at lower temperatures, at 29°C more sites are edited. These sites are less evolutionarily conserved, more disperse, less likely to be involved in secondary structures, and more likely to be located in exons. Interestingly, hypomorph mutants for ADAR display a weaker transcriptional response to temperature changes than wild-type flies and a highly abnormal behavioral response upon temperature increase. In sum, our data shows that ADAR is essential for proper temperature adaptation, a key behavior trait that is essential for survival of flies in the wild. Moreover, our results suggest a more general role of ADAR in regulating RNA secondary structures in vivo.

  4. Massive A-to-I RNA editing is common across the Metazoa and correlates with dsRNA abundance.

    PubMed

    Porath, Hagit T; Knisbacher, Binyamin A; Eisenberg, Eli; Levanon, Erez Y

    2017-10-02

    Adenosine to inosine (A-to-I) RNA editing is a post-transcriptional modification catalyzed by the ADAR (adenosine deaminase that acts on RNA) enzymes, which are ubiquitously expressed among metazoans. Technical requirements have limited systematic mapping of editing sites to a small number of organisms. Thus, the extent of editing across the metazoan lineage is largely unknown. Here, we apply a computational procedure to search for RNA-sequencing reads containing clusters of editing sites in 21 diverse organisms. Clusters of editing sites are abundant in repetitive genomic regions that putatively form double-stranded RNA (dsRNA) structures and are rarely seen in coding regions. The method reveals a considerable variation in hyper-editing levels across species, which is partly explained by differences in the potential of sequences to form dsRNA structures and the variability of ADAR proteins. Several commonly used model animals exhibit low editing levels and editing levels in primates is not exceptionally high, as previously suggested. Editing by ADARs is highly prevalent across the Metazoa, mostly targeting dsRNA structures formed by genomic repeats. The degree to which the transcriptome of a given species undergoes hyper-editing is governed by the repertoire of repeats in the underlying genome. The strong association of RNA editing with the long dsRNA regions originating from non-coding repetitive elements is contrasted by the almost non-existing signal seen in coding regions. Hyper-edited regions are rarely expressed in a non-edited form. These results support the notion that the main role of ADAR is to suppress the cellular response to endogenous dsRNA structures.

  5. A-to-I editing challenger or ally to the microRNA process.

    PubMed

    Ohman, M

    2007-10-01

    Adenosine to inosine (A-to-I) modification by the ADAR (adenosine deaminase that acts on RNA) enzymes perform the most common type of RNA editing in metazoans. ADARs use double stranded RNA as substrates but allow interruptions of bulges and loops in the structure. It is well known that these enzymes can use messenger RNA as targets for A-to-I editing and thereby recode the transcript. Both ADAR1 and ADAR2 have been proven to be able to also target short double stranded RNA molecules of the same size as a microRNA. However, it is not until recently shown that A-to-I editing occurs in microRNAs and its precursors. Since the editing activity is found both in the nucleus and the cytoplasm there are several steps during the microRNA maturation pathway that can be targeted for modification. This review will give an overview of what is known today about the interactions between the endogenous RNA interference process and RNA editing. It will also give some insight into the power of A-to-I modification in its ability to increase the variety of microRNA gene silencing.

  6. Altered A-to-I RNA Editing in Human Embryogenesis

    PubMed Central

    Mandel, Rachel; Ziskind, Anna; Nahor, Irit; Safran, Michal; Osenberg, Sivan; Sherf, Ofra; Rechavi, Gideon; Itskovitz-Eldor, Joseph

    2012-01-01

    Post-transcriptional events play an important role in human development. The question arises as to whether Adenosine to Inosine RNA editing, catalyzed by the ADAR (Adenosine Deaminase acting on RNA) enzymes, differs in human embryogenesis and in adulthood. We tested the editing of various target genes in coding (FLNA, BLCAP, CYFIP2) and non-coding sequences at their Alu elements (BRCA1, CARD11, RBBP9, MDM4, FNACC), as well as the transcriptional levels of the ADAR1 enzymes. This analysis was performed on five fetal and adult human tissues: brain, heart, liver, kidney, and spleen, as well as on human embryonic stem cells (hESCs), which represent the blastocyst stage in early human development. Our results show substantially greater editing activity for most adult tissue samples relative to fetal ones, in six of the eight genes tested. To test the effect of reduced A-to-I RNA editing activity in early human development we used human embryonic stem cells (hESCs) as a model and tried to generate hESC clones that overexpress the ADAR1–p110 isoform. We were unable to achieve overexpression of ADAR1–p110 by either transfection or lentiviral infection, though we easily generated hESC clones that expressed the GFP transgene and overexpressed ADAR1-p110 in 293T cells and in primary human foreskin fibroblast (HFF) cells. Moreover, in contrast to the expected overexpression of ADAR1-p110 protein following its introduction into hESCs, the expression levels of this protein decreased dramatically 24–48 hr post infection. Similar results were obtained when we tried to overexpress ADAR1-p110 in pluripotent embryonal carcinoma cells. This suggests that ADAR1 protein is substantially regulated in undifferentiated pluripotent hESCs. Overall, our data suggest that A-to-I RNA editing plays a critical role during early human development. PMID:22859999

  7. Altered A-to-I RNA editing in human embryogenesis.

    PubMed

    Shtrichman, Ronit; Germanguz, Igal; Mandel, Rachel; Ziskind, Anna; Nahor, Irit; Safran, Michal; Osenberg, Sivan; Sherf, Ofra; Rechavi, Gideon; Itskovitz-Eldor, Joseph

    2012-01-01

    Post-transcriptional events play an important role in human development. The question arises as to whether Adenosine to Inosine RNA editing, catalyzed by the ADAR (Adenosine Deaminase acting on RNA) enzymes, differs in human embryogenesis and in adulthood. We tested the editing of various target genes in coding (FLNA, BLCAP, CYFIP2) and non-coding sequences at their Alu elements (BRCA1, CARD11, RBBP9, MDM4, FNACC), as well as the transcriptional levels of the ADAR1 enzymes. This analysis was performed on five fetal and adult human tissues: brain, heart, liver, kidney, and spleen, as well as on human embryonic stem cells (hESCs), which represent the blastocyst stage in early human development. Our results show substantially greater editing activity for most adult tissue samples relative to fetal ones, in six of the eight genes tested. To test the effect of reduced A-to-I RNA editing activity in early human development we used human embryonic stem cells (hESCs) as a model and tried to generate hESC clones that overexpress the ADAR1-p110 isoform. We were unable to achieve overexpression of ADAR1-p110 by either transfection or lentiviral infection, though we easily generated hESC clones that expressed the GFP transgene and overexpressed ADAR1-p110 in 293T cells and in primary human foreskin fibroblast (HFF) cells. Moreover, in contrast to the expected overexpression of ADAR1-p110 protein following its introduction into hESCs, the expression levels of this protein decreased dramatically 24-48 hr post infection. Similar results were obtained when we tried to overexpress ADAR1-p110 in pluripotent embryonal carcinoma cells. This suggests that ADAR1 protein is substantially regulated in undifferentiated pluripotent hESCs. Overall, our data suggest that A-to-I RNA editing plays a critical role during early human development.

  8. Adaptation of A-to-I RNA editing in Drosophila.

    PubMed

    Duan, Yuange; Dou, Shengqian; Luo, Shiqi; Zhang, Hong; Lu, Jian

    2017-03-01

    Adenosine-to-inosine (A-to-I) editing is hypothesized to facilitate adaptive evolution by expanding proteomic diversity through an epigenetic approach. However, it is challenging to provide evidences to support this hypothesis at the whole editome level. In this study, we systematically characterized 2,114 A-to-I RNA editing sites in female and male brains of D. melanogaster, and nearly half of these sites had events evolutionarily conserved across Drosophila species. We detected strong signatures of positive selection on the nonsynonymous editing sites in Drosophila brains, and the beneficial editing sites were significantly enriched in genes related to chemical and electrical neurotransmission. The signal of adaptation was even more pronounced for the editing sites located in X chromosome or for those commonly observed across Drosophila species. We identified a set of gene candidates (termed "PSEB" genes) that had nonsynonymous editing events favored by natural selection. We presented evidence that editing preferentially increased mutation sequence space of evolutionarily conserved genes, which supported the adaptive evolution hypothesis of editing. We found prevalent nonsynonymous editing sites that were favored by natural selection in female and male adults from five strains of D. melanogaster. We showed that temperature played a more important role than gender effect in shaping the editing levels, although the effect of temperature is relatively weaker compared to that of species effect. We also explored the relevant factors that shape the selective patterns of the global editomes. Altogether we demonstrated that abundant nonsynonymous editing sites in Drosophila brains were adaptive and maintained by natural selection during evolution. Our results shed new light on the evolutionary principles and functional consequences of RNA editing.

  9. Adaptation of A-to-I RNA editing in Drosophila

    PubMed Central

    Zhang, Hong

    2017-01-01

    Adenosine-to-inosine (A-to-I) editing is hypothesized to facilitate adaptive evolution by expanding proteomic diversity through an epigenetic approach. However, it is challenging to provide evidences to support this hypothesis at the whole editome level. In this study, we systematically characterized 2,114 A-to-I RNA editing sites in female and male brains of D. melanogaster, and nearly half of these sites had events evolutionarily conserved across Drosophila species. We detected strong signatures of positive selection on the nonsynonymous editing sites in Drosophila brains, and the beneficial editing sites were significantly enriched in genes related to chemical and electrical neurotransmission. The signal of adaptation was even more pronounced for the editing sites located in X chromosome or for those commonly observed across Drosophila species. We identified a set of gene candidates (termed “PSEB” genes) that had nonsynonymous editing events favored by natural selection. We presented evidence that editing preferentially increased mutation sequence space of evolutionarily conserved genes, which supported the adaptive evolution hypothesis of editing. We found prevalent nonsynonymous editing sites that were favored by natural selection in female and male adults from five strains of D. melanogaster. We showed that temperature played a more important role than gender effect in shaping the editing levels, although the effect of temperature is relatively weaker compared to that of species effect. We also explored the relevant factors that shape the selective patterns of the global editomes. Altogether we demonstrated that abundant nonsynonymous editing sites in Drosophila brains were adaptive and maintained by natural selection during evolution. Our results shed new light on the evolutionary principles and functional consequences of RNA editing. PMID:28282384

  10. Regulatory factors governing adenosine-to-inosine (A-to-I) RNA editing.

    PubMed

    Hong, HuiQi; Lin, Jaymie Siqi; Chen, Leilei

    2015-03-31

    Adenosine-to-inosine (A-to-I) RNA editing, the most prevalent mode of transcript modification in higher eukaryotes, is catalysed by the adenosine deaminases acting on RNA (ADARs). A-to-I editing imposes an additional layer of gene regulation as it dictates various aspects of RNA metabolism, including RNA folding, processing, localization and degradation. Furthermore, editing events in exonic regions contribute to proteome diversity as translational machinery decodes inosine as guanosine. Although it has been demonstrated that dysregulated A-to-I editing contributes to various diseases, the precise regulatory mechanisms governing this critical cellular process have yet to be fully elucidated. However, integration of previous studies revealed that regulation of A-to-I editing is multifaceted, weaving an intricate network of auto- and transregulations, including the involvement of virus-originated factors like adenovirus-associated RNA. Taken together, it is apparent that tipping of any regulatory components will have profound effects on A-to-I editing, which in turn contributes to both normal and aberrant physiological conditions. A complete understanding of this intricate regulatory network may ultimately be translated into new therapeutic strategies against diseases driven by perturbed RNA editing events. Herein, we review the current state of knowledge on the regulatory mechanisms governing A-to-I editing and propose the role of other co-factors that may be involved in this complex regulatory process.

  11. Genome-wide A-to-I RNA editing in fungi independent of ADAR enzymes

    PubMed Central

    Liu, Huiquan; Wang, Qinhu; He, Yi; Chen, Lingfeng; Hao, Chaofeng; Jiang, Cong; Li, Yang; Dai, Yafeng; Kang, Zhensheng; Xu, Jin-Rong

    2016-01-01

    Yeasts and filamentous fungi do not have adenosine deaminase acting on RNA (ADAR) orthologs and are believed to lack A-to-I RNA editing, which is the most prevalent editing of mRNA in animals. However, during this study with the PUK1 (FGRRES_01058) pseudokinase gene important for sexual reproduction in Fusarium graminearum, we found that two tandem stop codons, UA1831GUA1834G, in its kinase domain were changed to UG1831GUG1834G by RNA editing in perithecia. To confirm A-to-I editing of PUK1 transcripts, strand-specific RNA-seq data were generated with RNA isolated from conidia, hyphae, and perithecia. PUK1 was almost specifically expressed in perithecia, and 90% of transcripts were edited to UG1831GUG1834G. Genome-wide analysis identified 26,056 perithecium-specific A-to-I editing sites. Unlike those in animals, 70.5% of A-to-I editing sites in F. graminearum occur in coding regions, and more than two-thirds of them result in amino acid changes, including editing of 69 PUK1-like pseudogenes with stop codons in ORFs. PUK1 orthologs and other pseudogenes also displayed stage-specific expression and editing in Neurospora crassa and F. verticillioides. Furthermore, F. graminearum differs from animals in the sequence preference and structure selectivity of A-to-I editing sites. Whereas A's embedded in RNA stems are targeted by ADARs, RNA editing in F. graminearum preferentially targets A's in hairpin loops, which is similar to the anticodon loop of tRNA targeted by adenosine deaminases acting on tRNA (ADATs). Overall, our results showed that A-to-I RNA editing occurs specifically during sexual reproduction and mainly in the coding regions in filamentous ascomycetes, involving adenosine deamination mechanisms distinct from metazoan ADARs. PMID:26934920

  12. Small RNA and A-to-I Editing in Autism Spectrum Disorders

    NASA Astrophysics Data System (ADS)

    Eran, Alal

    One in every 88 children is diagnosed with Autism Spectrum Disorders (ASDs), a set of neurodevelopmental conditions characterized by social impairments, communication deficits, and repetitive behavior. ASDs have a substantial genetic component, but the specific cause of most cases remains unknown. Understanding gene-environment interactions underlying ASD is essential for improving early diagnosis and identifying critical targets for intervention and prevention. Towards this goal, we surveyed adenosine-to-inosine (A-to-I) RNA editing in autistic brains. A-to-I editing is an epigenetic mechanism that fine-tunes synaptic function in response to environmental stimuli, shown to modulate complex behavior in animals. We used ultradeep sequencing to quantify A-to-I receding of candidate synaptic genes in postmortem cerebella from individuals with ASD and neurotypical controls. We found unexpectedly wide distributions of human A-to-I editing levels, whose extremes were consistently populated by individuals with ASD. We correlated A-to-I editing with isoform usage, identified clusters of correlated sites, and examined differential editing patterns. Importantly, we found that individuals with ASD commonly use a dysfunctional form of the editing enzyme ADARB1. We next profiled small RNAs thought to regulate A-to-I editing, which originate from one of the most commonly altered loci in ASD, 15q11. Deep targeted sequencing of SNORD115 and SNORD116 transcripts enabled their high-resolution detection in human brains, and revealed a strong gender bias underlying their expression. The consistent 2-fold upregulation of 15q11 small RNAs in male vs. female cerebella could be important in delineating the role of this locus in ASD, a male dominant disorder. Overall, these studies provide an accurate population-level view of small RNA and A-to-I editing in human cerebella, and suggest that A-to-I editing of synaptic genes may be informative for assessing the epigenetic risk for autism

  13. Discriminative Prediction of A-To-I RNA Editing Events from DNA Sequence

    PubMed Central

    Sun, Jiangming; Singh, Pratibha; Bagge, Annika; Valtat, Bérengère; Vikman, Petter; Spégel, Peter; Mulder, Hindrik

    2016-01-01

    RNA editing is a post-transcriptional alteration of RNA sequences that, via insertions, deletions or base substitutions, can affect protein structure as well as RNA and protein expression. Recently, it has been suggested that RNA editing may be more frequent than previously thought. A great impediment, however, to a deeper understanding of this process is the paramount sequencing effort that needs to be undertaken to identify RNA editing events. Here, we describe an in silico approach, based on machine learning, that ameliorates this problem. Using 41 nucleotide long DNA sequences, we show that novel A-to-I RNA editing events can be predicted from known A-to-I RNA editing events intra- and interspecies. The validity of the proposed method was verified in an independent experimental dataset. Using our approach, 203 202 putative A-to-I RNA editing events were predicted in the whole human genome. Out of these, 9% were previously reported. The remaining sites require further validation, e.g., by targeted deep sequencing. In conclusion, the approach described here is a useful tool to identify potential A-to-I RNA editing events without the requirement of extensive RNA sequencing. PMID:27764195

  14. A Role for A-to-I RNA Editing in Temperature Adaptation

    PubMed Central

    Garrett, Sandra C.; Rosenthal, Joshua J. C.

    2014-01-01

    A-to-I RNA editing can recode mRNAs, giving organisms the option to express diverse, functionally distinct protein isoforms. Here, we propose that RNA editing is inherently geared for temperature adaptation because it tends to recode to smaller, less stabilizing amino acids. Studies on how editing affects protein function support this idea. PMID:23223630

  15. Accurate identification of A-to-I RNA editing in human by transcriptome sequencing.

    PubMed

    Bahn, Jae Hoon; Lee, Jae-Hyung; Li, Gang; Greer, Christopher; Peng, Guangdun; Xiao, Xinshu

    2012-01-01

    RNA editing enhances the diversity of gene products at the post-transcriptional level. Approaches for genome-wide identification of RNA editing face two main challenges: separating true editing sites from false discoveries and accurate estimation of editing levels. We developed an approach to analyze transcriptome sequencing data (RNA-seq) for global identification of RNA editing in cells for which whole-genome sequencing data are available. We applied the method to analyze RNA-seq data of a human glioblastoma cell line, U87MG. Around 10,000 DNA-RNA differences were identified, the majority being putative A-to-I editing sites. These predicted A-to-I events were associated with a low false-discovery rate (∼5%). Moreover, the estimated editing levels from RNA-seq correlated well with those based on traditional clonal sequencing. Our results further facilitated unbiased characterization of the sequence and evolutionary features flanking predicted A-to-I editing sites and discovery of a conserved RNA structural motif that may be functionally relevant to editing. Genes with predicted A-to-I editing were significantly enriched with those known to be involved in cancer, supporting the potential importance of cancer-specific RNA editing. A similar profile of DNA-RNA differences as in U87MG was predicted for another RNA-seq data set obtained from primary breast cancer samples. Remarkably, significant overlap exists between the putative editing sites of the two transcriptomes despite their difference in cell type, cancer type, and genomic backgrounds. Our approach enabled de novo identification of the RNA editome, which sets the stage for further mechanistic studies of this important step of post-transcriptional regulation.

  16. REDIportal: a comprehensive database of A-to-I RNA editing events in humans

    PubMed Central

    Picardi, Ernesto; D'Erchia, Anna Maria; Lo Giudice, Claudio; Pesole, Graziano

    2017-01-01

    RNA editing by A-to-I deamination is the prominent co-/post-transcriptional modification in humans. It is carried out by ADAR enzymes and contributes to both transcriptomic and proteomic expansion. RNA editing has pivotal cellular effects and its deregulation has been linked to a variety of human disorders including neurological and neurodegenerative diseases and cancer. Despite its biological relevance, many physiological and functional aspects of RNA editing are yet elusive. Here, we present REDIportal, available online at http://srv00.recas.ba.infn.it/atlas/, the largest and comprehensive collection of RNA editing in humans including more than 4.5 millions of A-to-I events detected in 55 body sites from thousands of RNAseq experiments. REDIportal embeds RADAR database and represents the first editing resource designed to answer functional questions, enabling the inspection and browsing of editing levels in a variety of human samples, tissues and body sites. In contrast with previous RNA editing databases, REDIportal comprises its own browser (JBrowse) that allows users to explore A-to-I changes in their genomic context, empathizing repetitive elements in which RNA editing is prominent. PMID:27587585

  17. Comparative analysis of A-to-I editing in human and non-human primate brains reveals conserved patterns and context-dependent regulation of RNA editing.

    PubMed

    O'Neil, Richard T; Wang, Xiaojing; Morabito, Michael V; Emeson, Ronald B

    2017-04-06

    A-to-I RNA editing is an important process for generating molecular diversity in the brain through modification of transcripts encoding several proteins important for neuronal signaling. We investigated the relationships between the extent of editing at multiple substrate transcripts (5HT2C, MGLUR4, CADPS, GLUR2, GLUR4, and GABRA3) in brain tissue obtained from adult humans and rhesus macaques. Several patterns emerged from these studies revealing conservation of editing across primate species. Additionally, variability in the human population allows us to make novel inferences about the co-regulation of editing at different editing sites and even across different brain regions.

  18. Screening of human SNP database identifies recoding sites of A-to-I RNA editing

    PubMed Central

    Gommans, Willemijn M.; Tatalias, Nicholas E.; Sie, Christina P.; Dupuis, Dylan; Vendetti, Nicholas; Smith, Lauren; Kaushal, Rikhi; Maas, Stefan

    2008-01-01

    Single nucleotide polymorphisms (SNPs) are DNA sequence variations that can affect the expression or function of genes. As a result, they may lead to phenotypic differences between individuals, such as susceptibility to disease, response to medications, and disease progression. Millions of SNPs have been mapped within the human genome providing a rich resource for genetic variation studies. Adenosine-to-inosine RNA editing also leads to the production of RNA and protein sequence variants, but it acts on the level of primary gene transcripts. Sequence variations due to RNA editing may be misannotated as SNPs when relying solely on expressed sequence data instead of genomic material. In this study, we screened the human SNP database for potential cases of A-to-I RNA editing that cause amino acid changes in the encoded protein. Our search strategy applies five molecular features to score candidate sites. It identifies all previously known cases of editing present in the SNP database and successfully uncovers novel, bona fide targets of adenosine deamination editing. Our approach sets the stage for effective and comprehensive genome-wide screens for A-to-I editing targets. PMID:18772245

  19. Reduced levels of protein recoding by A-to-I RNA editing in Alzheimer's disease

    PubMed Central

    Khermesh, Khen; D'Erchia, Anna Maria; Barak, Michal; Annese, Anita; Wachtel, Chaim; Levanon, Erez Y.; Picardi, Ernesto; Eisenberg, Eli

    2016-01-01

    Adenosine to inosine (A-to-I) RNA editing, catalyzed by the ADAR enzyme family, acts on dsRNA structures within pre-mRNA molecules. Editing of the coding part of the mRNA may lead to recoding, amino acid substitution in the resulting protein, possibly modifying its biochemical and biophysical properties. Altered RNA editing patterns have been observed in various neurological pathologies. Here, we present a comprehensive study of recoding by RNA editing in Alzheimer's disease (AD), the most common cause of irreversible dementia. We have used a targeted resequencing approach supplemented by a microfluidic-based high-throughput PCR coupled with next-generation sequencing to accurately quantify A-to-I RNA editing levels in a preselected set of target sites, mostly located within the coding sequence of synaptic genes. Overall, editing levels decreased in AD patients’ brain tissues, mainly in the hippocampus and to a lesser degree in the temporal and frontal lobes. Differential RNA editing levels were observed in 35 target sites within 22 genes. These results may shed light on a possible association between the neurodegenerative processes typical for AD and deficient RNA editing. PMID:26655226

  20. Deciphering the functions and regulation of brain-enriched A-to-I RNA editing.

    PubMed

    Li, Jin Billy; Church, George M

    2013-11-01

    Adenosine-to-inosine (A-to-I) RNA editing, in which genomically encoded adenosine is changed to inosine in RNA, is catalyzed by adenosine deaminase acting on RNA (ADAR). This fine-tuning mechanism is critical during normal development and diseases, particularly in relation to brain functions. A-to-I RNA editing has also been hypothesized to be a driving force in human brain evolution. A large number of RNA editing sites have recently been identified, mostly as a result of the development of deep sequencing and bioinformatic analyses. Deciphering the functional consequences of RNA editing events is challenging, but emerging genome engineering approaches may expedite new discoveries. To understand how RNA editing is dynamically regulated, it is imperative to construct a spatiotemporal atlas at the species, tissue and cell levels. Future studies will need to identify the cis and trans regulatory factors that drive the selectivity and frequency of RNA editing. We anticipate that recent technological advancements will aid researchers in acquiring a much deeper understanding of the functions and regulation of RNA editing.

  1. A-to-I editing of coding and non-coding RNAs by ADARs

    PubMed Central

    Nishikura, Kazuko

    2016-01-01

    Adenosine deaminases acting on RNA (ADARs) convert adenosine to inosine in double-stranded RNA. This A-to-I editing occurs not only in protein-coding regions of mRNAs, but also frequently in non-coding regions that contain inverted Alu repeats. Editing of coding sequences can result in the expression of functionally altered proteins that are not encoded in the genome, whereas the significance of Alu editing remains largely unknown. Certain microRNA (miRNA) precursors are also edited, leading to reduced expression or altered function of mature miRNAs. Conversely, recent studies indicate that ADAR1 forms a complex with Dicer to promote miRNA processing, revealing a new function of ADAR1 in the regulation of RNA interference. PMID:26648264

  2. Principles Governing A-to-I RNA Editing in the Breast Cancer Transcriptome.

    PubMed

    Fumagalli, Debora; Gacquer, David; Rothé, Françoise; Lefort, Anne; Libert, Frederick; Brown, David; Kheddoumi, Naima; Shlien, Adam; Konopka, Tomasz; Salgado, Roberto; Larsimont, Denis; Polyak, Kornelia; Willard-Gallo, Karen; Desmedt, Christine; Piccart, Martine; Abramowicz, Marc; Campbell, Peter J; Sotiriou, Christos; Detours, Vincent

    2015-10-13

    Little is known about how RNA editing operates in cancer. Transcriptome analysis of 68 normal and cancerous breast tissues revealed that the editing enzyme ADAR acts uniformly, on the same loci, across tissues. In controlled ADAR expression experiments, the editing frequency increased at all loci with ADAR expression levels according to the logistic model. Loci-specific "editabilities," i.e., propensities to be edited by ADAR, were quantifiable by fitting the logistic function to dose-response data. The editing frequency was increased in tumor cells in comparison to normal controls. Type I interferon response and ADAR DNA copy number together explained 53% of ADAR expression variance in breast cancers. ADAR silencing using small hairpin RNA lentivirus transduction in breast cancer cell lines led to less cell proliferation and more apoptosis. A-to-I editing is a pervasive, yet reproducible, source of variation that is globally controlled by 1q amplification and inflammation, both of which are highly prevalent among human cancers.

  3. A-to-I RNA editing is developmentally regulated and generally adaptive for sexual reproduction in Neurospora crassa.

    PubMed

    Liu, Huiquan; Li, Yang; Chen, Daipeng; Qi, Zhaomei; Wang, Qinhu; Wang, Jianhua; Jiang, Cong; Xu, Jin-Rong

    2017-09-12

    Although fungi lack adenosine deaminase acting on RNA (ADAR) enzymes, adenosine to inosine (A-to-I) RNA editing was reported recently in Fusarium graminearum during sexual reproduction. In this study, we profiled the A-to-I editing landscape and characterized its functional and adaptive properties in the model filamentous fungus Neurospora crassa A total of 40,677 A-to-I editing sites were identified, and approximately half of them displayed stage-specific editing or editing levels at different sexual stages. RNA-sequencing analysis with the Δstc-1 and Δsad-1 mutants confirmed A-to-I editing occurred before ascus development but became more prevalent during ascosporogenesis. Besides fungal-specific sequence and secondary structure preference, 63.5% of A-to-I editing sites were in the coding regions and 81.3% of them resulted in nonsynonymous recoding, resulting in a significant increase in the proteome complexity. Many genes involved in RNA silencing, DNA methylation, and histone modifications had extensive recoding, including sad-1, sms-3, qde-1, and dim-2. Fifty pseudogenes harbor premature stop codons that require A-to-I editing to encode full-length proteins. Unlike in humans, nonsynonymous editing events in N. crassa are generally beneficial and favored by positive selection. Almost half of the nonsynonymous editing sites in N. crassa are conserved and edited in Neurospora tetrasperma Furthermore, hundreds of them are conserved in F. graminearum and had higher editing levels. Two unknown genes with editing sites conserved between Neurospora and Fusarium were experimentally shown to be important for ascosporogenesis. This study comprehensively analyzed A-to-I editing in N. crassa and showed that RNA editing is stage-specific and generally adaptive, and may be functionally related to repeat induced point mutation and meiotic silencing by unpaired DNA.

  4. The Landscape of A-to-I RNA Editome Is Shaped by Both Positive and Purifying Selection

    PubMed Central

    Kong, Yimeng; Pan, Bohu; Chen, Longxian; Wang, Hongbing; Hao, Pei; Li, Xuan

    2016-01-01

    The hydrolytic deamination of adenosine to inosine (A-to-I editing) in precursor mRNA induces variable gene products at the post-transcription level. How and to what extent A-to-I RNA editing diversifies transcriptome is not fully characterized in the evolution, and very little is known about the selective constraints that drive the evolution of RNA editing events. Here we present a study on A-to-I RNA editing, by generating a global profile of A-to-I editing for a phylogeny of seven Drosophila species, a model system spanning an evolutionary timeframe of approximately 45 million years. Of totally 9281 editing events identified, 5150 (55.5%) are located in the coding sequences (CDS) of 2734 genes. Phylogenetic analysis places these genes into 1,526 homologous families, about 5% of total gene families in the fly lineages. Based on conservation of the editing sites, the editing events in CDS are categorized into three distinct types, representing events on singleton genes (type I), and events not conserved (type II) or conserved (type III) within multi-gene families. While both type I and II events are subject to purifying selection, notably type III events are positively selected, and highly enriched in the components and functions of the nervous system. The tissue profiles are documented for three editing types, and their critical roles are further implicated by their shifting patterns during holometabolous development and in post-mating response. In conclusion, three A-to-I RNA editing types are found to have distinct evolutionary dynamics. It appears that nervous system functions are mainly tested to determine if an A-to-I editing is beneficial for an organism. The coding plasticity enabled by A-to-I editing creates a new class of binary variations, which is a superior alternative to maintain heterozygosity of expressed genes in a diploid mating system. PMID:27467689

  5. Construction of a guide-RNA for site-directed RNA mutagenesis utilising intracellular A-to-I RNA editing.

    PubMed

    Fukuda, Masatora; Umeno, Hiromitsu; Nose, Kanako; Nishitarumizu, Azusa; Noguchi, Ryoma; Nakagawa, Hiroyuki

    2017-02-02

    As an alternative to DNA mutagenesis, RNA mutagenesis can potentially become a powerful gene-regulation method for fundamental research and applied life sciences. Adenosine-to-inosine (A-to-I) RNA editing alters genetic information at the transcript level and is an important biological process that is commonly conserved in metazoans. Therefore, a versatile RNA-mutagenesis method can be achieved by utilising the intracellular RNA-editing mechanism. Here, we report novel guide RNAs capable of inducing A-to-I mutations by guiding the editing enzyme, human adenosine deaminase acting on RNA (ADAR). These guide RNAs successfully introduced A-to-I mutations into the target-site, which was determined by the reprogrammable antisense region. In ADAR2-over expressing cells, site-directed RNA editing could also be performed by simply introducing the guide RNA. Our guide RNA framework provides basic insights into establishing a generally applicable RNA-mutagenesis method.

  6. Construction of a guide-RNA for site-directed RNA mutagenesis utilising intracellular A-to-I RNA editing

    PubMed Central

    Fukuda, Masatora; Umeno, Hiromitsu; Nose, Kanako; Nishitarumizu, Azusa; Noguchi, Ryoma; Nakagawa, Hiroyuki

    2017-01-01

    As an alternative to DNA mutagenesis, RNA mutagenesis can potentially become a powerful gene-regulation method for fundamental research and applied life sciences. Adenosine-to-inosine (A-to-I) RNA editing alters genetic information at the transcript level and is an important biological process that is commonly conserved in metazoans. Therefore, a versatile RNA-mutagenesis method can be achieved by utilising the intracellular RNA-editing mechanism. Here, we report novel guide RNAs capable of inducing A-to-I mutations by guiding the editing enzyme, human adenosine deaminase acting on RNA (ADAR). These guide RNAs successfully introduced A-to-I mutations into the target-site, which was determined by the reprogrammable antisense region. In ADAR2-over expressing cells, site-directed RNA editing could also be performed by simply introducing the guide RNA. Our guide RNA framework provides basic insights into establishing a generally applicable RNA-mutagenesis method. PMID:28148949

  7. The Genomic Landscape and Clinical Relevance of A-to-I RNA Editing in Human Cancers | Office of Cancer Genomics

    Cancer.gov

    Adenosine-to-inosine (A-to-I) RNA editing is a widespread post-transcriptional mechanism, but its genomic landscape and clinical relevance in cancer have not been investigated systematically. We characterized the global A-to-I RNA editing profiles of 6,236 patient samples of 17 cancer types from The Cancer Genome Atlas and revealed a striking diversity of altered RNA-editing patterns in tumors relative to normal tissues. We identified an appreciable number of clinically relevant editing events, many of which are in noncoding regions.

  8. Abnormalities in A-to-I RNA editing patterns in CNS injuries correlate with dynamic changes in cell type composition

    PubMed Central

    Gal-Mark, Nurit; Shallev, Lea; Sweetat, Sahar; Barak, Michal; Billy Li, Jin; Levanon, Erez Y.; Eisenberg, Eli; Behar, Oded

    2017-01-01

    Adenosine to Inosine (A-to-I) RNA editing is a co- or post-transcriptional mechanism that modifies genomically encoded nucleotides at the RNA level. A-to-I RNA editing is abundant in the brain, and altered editing levels have been reported in various neurological pathologies and following spinal cord injury (SCI). The prevailing concept is that the RNA editing process itself is dysregulated by brain pathologies. Here we analyzed recent RNA-seq data, and found that, except for few mammalian conserved editing sites, editing is significantly higher in neurons than in other cell populations of the brain. We studied A-to-I RNA editing in stab wound injury (SWI) and SCI models and showed that the apparent under-editing observed after injury correlates with an approximately 20% reduction in the relative density of neurons, due to cell death and immune cell infiltration that may account for the observed under-editing. Studies of neuronal and astrocyte cultures and a computational analysis of SCI RNA-seq data further supported the possibility that a reduction in neuronal density is responsible for alterations in the tissue-wide editing patterns upon injury. Thus, our data suggest that the case for a mechanistic linkage between A-to-I RNA editing and brain pathologies should be revisited. PMID:28266523

  9. Abnormalities in A-to-I RNA editing patterns in CNS injuries correlate with dynamic changes in cell type composition.

    PubMed

    Gal-Mark, Nurit; Shallev, Lea; Sweetat, Sahar; Barak, Michal; Billy Li, Jin; Levanon, Erez Y; Eisenberg, Eli; Behar, Oded

    2017-03-07

    Adenosine to Inosine (A-to-I) RNA editing is a co- or post-transcriptional mechanism that modifies genomically encoded nucleotides at the RNA level. A-to-I RNA editing is abundant in the brain, and altered editing levels have been reported in various neurological pathologies and following spinal cord injury (SCI). The prevailing concept is that the RNA editing process itself is dysregulated by brain pathologies. Here we analyzed recent RNA-seq data, and found that, except for few mammalian conserved editing sites, editing is significantly higher in neurons than in other cell populations of the brain. We studied A-to-I RNA editing in stab wound injury (SWI) and SCI models and showed that the apparent under-editing observed after injury correlates with an approximately 20% reduction in the relative density of neurons, due to cell death and immune cell infiltration that may account for the observed under-editing. Studies of neuronal and astrocyte cultures and a computational analysis of SCI RNA-seq data further supported the possibility that a reduction in neuronal density is responsible for alterations in the tissue-wide editing patterns upon injury. Thus, our data suggest that the case for a mechanistic linkage between A-to-I RNA editing and brain pathologies should be revisited.

  10. Power electronics substrate for direct substrate cooling

    DOEpatents

    Le, Khiet [Mission Viejo, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA; Yankoski, Edward P [Corona, CA; Smith, Gregory S [Woodland Hills, CA

    2012-05-01

    Systems and apparatus are provided for power electronics substrates adapted for direct substrate cooling. A power electronics substrate comprises a first surface configured to have electrical circuitry disposed thereon, a second surface, and a plurality of physical features on the second surface. The physical features are configured to promote a turbulent boundary layer in a coolant impinged upon the second surface.

  11. A-to-I RNA Editing: Current Knowledge Sources and Computational Approaches with Special Emphasis on Non-Coding RNA Molecules

    PubMed Central

    Nigita, Giovanni; Veneziano, Dario; Ferro, Alfredo

    2015-01-01

    RNA editing is a dynamic mechanism for gene regulation attained through the alteration of the sequence of primary RNA transcripts. A-to-I (adenosine-to-inosine) RNA editing, which is catalyzed by members of the adenosine deaminase acting on RNA (ADAR) family of enzymes, is the most common post-transcriptional modification in humans. The ADARs bind double-stranded regions and deaminate adenosine (A) into inosine (I), which in turn is interpreted by the translation and splicing machineries as guanosine (G). In recent years, this modification has been discovered to occur not only in coding RNAs but also in non-coding RNAs (ncRNA), such as microRNAs, small interfering RNAs, transfer RNAs, and long non-coding RNAs. This may have several consequences, such as the creation or disruption of microRNA/mRNA binding sites, and thus affect the biogenesis, stability, and target recognition properties of ncRNAs. The malfunction of the editing machinery is not surprisingly associated with various human diseases, such as neurodegenerative, cardiovascular, and carcinogenic diseases. Despite the enormous efforts made so far, the real biological function of this phenomenon, as well as the features of the ADAR substrate, in particular in non-coding RNAs, has still not been fully understood. In this work, we focus on the current knowledge of RNA editing on ncRNA molecules and provide a few examples of computational approaches to elucidate its biological function. PMID:25859542

  12. Alu sequences in undifferentiated human embryonic stem cells display high levels of A-to-I RNA editing.

    PubMed

    Osenberg, Sivan; Paz Yaacov, Nurit; Safran, Michal; Moshkovitz, Sharon; Shtrichman, Ronit; Sherf, Ofra; Jacob-Hirsch, Jasmine; Keshet, Gilmor; Amariglio, Ninette; Itskovitz-Eldor, Joseph; Rechavi, Gideon

    2010-06-21

    Adenosine to Inosine (A-to-I) RNA editing is a site-specific modification of RNA transcripts, catalyzed by members of the ADAR (Adenosine Deaminase Acting on RNA) protein family. RNA editing occurs in human RNA in thousands of different sites. Some of the sites are located in protein-coding regions but the majority is found in non-coding regions, such as 3'UTRs, 5'UTRs and introns - mainly in Alu elements. While editing is found in all tissues, the highest levels of editing are found in the brain. It was shown that editing levels within protein-coding regions are increased during embryogenesis and after birth and that RNA editing is crucial for organism viability as well as for normal development. In this study we characterized the A-to-I RNA editing phenomenon during neuronal and spontaneous differentiation of human embryonic stem cells (hESCs). We identified high editing levels of Alu repetitive elements in hESCs and demonstrated a global decrease in editing levels of non-coding Alu sites when hESCs are differentiating, particularly into the neural lineage. Using RNA interference, we showed that the elevated editing levels of Alu elements in undifferentiated hESCs are highly dependent on ADAR1. DNA microarray analysis showed that ADAR1 knockdown has a global effect on gene expression in hESCs and leads to a significant increase in RNA expression levels of genes involved in differentiation and development processes, including neurogenesis. Taken together, we speculate that A-to-I editing of Alu sequences plays a role in the regulation of hESC early differentiation decisions.

  13. Trans and cis factors affecting A-to-I RNA editing efficiency of a noncoding editing target in C. elegans.

    PubMed

    Washburn, Michael C; Hundley, Heather A

    2016-05-01

    Adenosine-to-inosine RNA editing by ADARs affects thousands of adenosines in an organism's transcriptome. However, adenosines are not edited at equal levels nor do these editing levels correlate well with ADAR expression levels. Therefore, additional mechanisms are utilized by the cell to dictate the editing efficiency at a given adenosine. To examine cis-and trans-acting factors that regulate A-to-I editing levels specifically in neural cells, we utilized the model organism Caenorhabditis elegans We demonstrate that a double-stranded RNA (dsRNA) binding protein, ADR-1, inhibits editing in neurons, which is largely masked when examining editing levels from whole animals. Furthermore, expression of ADR-1 and mRNA expression of the editing target can act synergistically to regulate editing efficiency. In addition, we identify a dsRNA region within the Y75B8A.83' UTR that acts as acis-regulatory element by enhancing ADR-2 editing efficiency. Together, this work identifies mechanisms that regulate editing efficiency of noncoding A-to-I editing sites, which comprise the largest class of ADAR targets. © 2016 Washburn and Hundley; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  14. Transcript Diversification in the Nervous System: A to I RNA Editing in CNS Function and Disease Development

    PubMed Central

    Tariq, Aamira; Jantsch, Michael F.

    2012-01-01

    RNA editing by adenosine deaminases that act on RNA converts adenosines to inosines in coding and non-coding regions of mRNAs. Inosines are interpreted as guanosines and hence, this type of editing can change codons, alter splice patterns, or influence the fate of an RNA. A to I editing is most abundant in the central nervous system (CNS). Here, targets for this type of nucleotide modification frequently encode receptors and channels. In many cases, the editing-induced amino acid exchanges alter the properties of the receptors and channels. Consistently, changes in editing patterns are frequently found associated with diseases of the CNS. In this review we describe the mechanisms of RNA editing and focus on target mRNAs of editing that are functionally relevant to normal and aberrant CNS activity. PMID:22787438

  15. Ribbed electrode substrates

    DOEpatents

    Breault, Richard D.; Goller, Glen J.

    1983-01-01

    A ribbed substrate for an electrochemical cell electrode is made from a mixture of carbon fibers and carbonizable resin and has a mean pore size in the ribs which is 60-75% of the mean pore size of the web portions of the substrate which interconnect the ribs. Preferably the mean pore size of the web portion is 25-45 microns; and, if the substrate includes edge seals parallel to the ribs, the edge seals preferably have a mean pore size no greater than about ten microns. Most preferably the substrate has the same ratio of carbon fibers to polymeric carbon in all areas, including the ribs, webs, and edge seals. A substrate according to the present invention will have better overall performance than prior art substrates and minimizes the substrate thickness required for the substrate to perform all its functions well.

  16. Coated substrates and process

    DOEpatents

    Chu, Wei-kan; Childs, Charles B.

    1991-01-01

    Disclosed herein is a coated substrate and a process for forming films on substrates and for providing a particularly smooth film on a substrate. The method of this invention involves subjecting a surface of a substrate to contact with a stream of ions of an inert gas having sufficient force and energy to substantially change the surface characteristics of said substrate, and then exposing a film-forming material to a stream of ions of an inert gas having sufficient energy to vaporize the atoms of said film-forming material and to transmit the vaporized atoms to the substrate surface with sufficient force to form a film bonded to the substrate. This process is particularly useful commercially because it forms strong bonds at room temperature. This invention is particularly useful for adhering a gold film to diamond and forming ohmic electrodes on diamond, but also can be used to bond other films to substrates.

  17. Polished polymide substrate

    DOEpatents

    Farah, John; Sudarshanam, Venkatapuram S.

    2003-05-13

    Polymer substrates, in particular polyimide substrates, and polymer laminates for optical applications are described. Polyimide substrates are polished on one or both sides depending on their thickness, and single-layer or multi-layer waveguide structures are deposited on the polished polyimide substrates. Optical waveguide devices are machined by laser ablation using a combination of IR and UV lasers. A waveguide-fiber coupler with a laser-machined groove for retaining the fiber is also disclosed.

  18. Systematic characterization of A-to-I RNA editing hotspots in microRNAs across human cancers.

    PubMed

    Wang, Yumeng; Xu, Xiaoyan; Yu, Shuangxing; Kang, Kang Jin; Zhou, Zhicheng; Han, Leng; Tsang, Yiu Huen; Li, Jun; Chen, Hu; Mangala, Lingegowda S; Yuan, Yuan; Eterovic, A Karina; Lu, Yiling; Sood, Anil K; Scott, Kenneth L; Mills, Gordon B; Liang, Han

    2017-04-14

    RNA editing, a widespread posttranscriptional mechanism, has emerged as a new player in cancer biology. Recent studies have reported key roles for individual miRNA editing events, but a comprehensive picture of miRNA editing in human cancers remains largely unexplored. Here we systematically characterized the miRNA editing profiles of 8,595 samples across 20 cancer types from miRNA sequencing data of The Cancer Genome Atlas and identified 19 adenosine-to-inosine (A-to-I) RNA editing hotspots. We independently validated 15 of them by perturbation experiments in several cancer cell lines. These miRNA editing events show extensive correlations with key clinical variables (e.g., tumor subtype, disease stage and patient survival time) and other molecular drivers. Focusing on the RNA editing hotspot in miR-200b, a key tumor metastasis suppressor, we found that the miR-200b editing level correlates with patient prognosis opposite to that pattern for the wild-type miR-200b expression. We further experimentally demonstrated that in contrast to wild-type miRNA, the edited miR-200b can promote cell invasion and migration through its impaired ability to inhibit ZEB1/ZEB2 and acquired concomitant ability to repress new targets including LIFR, a well-characterized metastasis suppressor. Our study highlights the importance of miRNA editing in gene regulation and suggests its potential as biomarkers for cancer prognosis and therapy.

  19. A-to-I RNA editing promotes developmental stage-specific gene and lncRNA expression.

    PubMed

    Goldstein, Boaz; Agranat-Tamir, Lily; Light, Dean; Ben-Naim Zgayer, Orna; Fishman, Alla; Lamm, Ayelet T

    2017-03-01

    A-to-I RNA editing is a conserved widespread phenomenon in which adenosine (A) is converted to inosine (I) by adenosine deaminases (ADARs) in double-stranded RNA regions, mainly noncoding. Mutations in ADAR enzymes in Caenorhabditis elegans cause defects in normal development but are not lethal as in human and mouse. Previous studies in C. elegans indicated competition between RNA interference (RNAi) and RNA editing mechanisms, based on the observation that worms that lack both mechanisms do not exhibit defects, in contrast to the developmental defects observed when only RNA editing is absent. To study the effects of RNA editing on gene expression and function, we established a novel screen that enabled us to identify thousands of RNA editing sites in nonrepetitive regions in the genome. These include dozens of genes that are edited at their 3' UTR region. We found that these genes are mainly germline and neuronal genes, and that they are down-regulated in the absence of ADAR enzymes. Moreover, we discovered that almost half of these genes are edited in a developmental-specific manner, indicating that RNA editing is a highly regulated process. We found that many pseudogenes and other lncRNAs are also extensively down-regulated in the absence of ADARs in the embryo but not in the fourth larval (L4) stage. This down-regulation is not observed upon additional knockout of RNAi. Furthermore, levels of siRNAs aligned to pseudogenes in ADAR mutants are enhanced. Taken together, our results suggest a role for RNA editing in normal growth and development by regulating silencing via RNAi.

  20. A-to-I RNA editing promotes developmental stage–specific gene and lncRNA expression

    PubMed Central

    Goldstein, Boaz; Agranat-Tamir, Lily; Light, Dean; Ben-Naim Zgayer, Orna; Fishman, Alla; Lamm, Ayelet T.

    2017-01-01

    A-to-I RNA editing is a conserved widespread phenomenon in which adenosine (A) is converted to inosine (I) by adenosine deaminases (ADARs) in double-stranded RNA regions, mainly noncoding. Mutations in ADAR enzymes in Caenorhabditis elegans cause defects in normal development but are not lethal as in human and mouse. Previous studies in C. elegans indicated competition between RNA interference (RNAi) and RNA editing mechanisms, based on the observation that worms that lack both mechanisms do not exhibit defects, in contrast to the developmental defects observed when only RNA editing is absent. To study the effects of RNA editing on gene expression and function, we established a novel screen that enabled us to identify thousands of RNA editing sites in nonrepetitive regions in the genome. These include dozens of genes that are edited at their 3′ UTR region. We found that these genes are mainly germline and neuronal genes, and that they are down-regulated in the absence of ADAR enzymes. Moreover, we discovered that almost half of these genes are edited in a developmental-specific manner, indicating that RNA editing is a highly regulated process. We found that many pseudogenes and other lncRNAs are also extensively down-regulated in the absence of ADARs in the embryo but not in the fourth larval (L4) stage. This down-regulation is not observed upon additional knockout of RNAi. Furthermore, levels of siRNAs aligned to pseudogenes in ADAR mutants are enhanced. Taken together, our results suggest a role for RNA editing in normal growth and development by regulating silencing via RNAi. PMID:28031250

  1. Lightweight Substrates For Mirrors

    NASA Technical Reports Server (NTRS)

    Brown, D. Kyle

    1991-01-01

    New substrate uses conventional quasi-isotropic fabric laminate with surfacing layer of carbon-fiber paper consisting of randomly oriented chopped carbon fibers. Layered structure of fabric and paper relatively easy to manufacture. When impregnated with carbon, structure rigid and stable. Substrates of this type made quite thin, thus keeping areal weights to minimum. Mirrors of this type made faster, and cost less, than predecessors.

  2. Bonded semiconductor substrate

    DOEpatents

    Atwater, Jr.; Harry A. , Zahler; James M.

    2010-07-13

    Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

  3. Decontamination of metal substrates

    SciTech Connect

    Vincent, L.D.

    1998-12-31

    A brief look at the history of surface corrosion and contamination of steel is important for understanding the best approach to proper cleaning of substrates prior to surface preparation and application of coatings and linings, particularly in immersion conditions such as encountered in railroad hopper and tank cars. All contaminants contribute to reduction of the coating or lining`s capacity to either protect the substrate or prevent contamination of the liquid cargo. This paper will explore the types of tests available to determine the levels of contamination, particularly sulfides, sulfates and chlorides, along with suggested methods to reduce theses contaminants to acceptable levels.

  4. Biaxially textured composite substrates

    DOEpatents

    Groves, James R.; Foltyn, Stephen R.; Arendt, Paul N.

    2005-04-26

    An article including a substrate, a layer of a metal phosphate material such as an aluminum phosphate material upon the surface of the substrate, and a layer of an oriented cubic oxide material having a rock-salt-like structure upon the metal phosphate material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon a layer of a buffer material such as a SrTi.sub.x Ru.sub.1-x O.sub.3 layer.

  5. Enamides: valuable organic substrates.

    PubMed

    Carbery, David R

    2008-10-07

    Enamides display a fine balance of stability and reactivity, which is now leading to their increasing use in organic synthesis. Enamides offer multiple opportunities for the inclusion of nitrogen based functionality into organic systems. Recent examples of these compounds as substrates are discussed in this article.

  6. Multiple alternative substrate kinetics.

    PubMed

    Anderson, Vernon E

    2015-11-01

    The specificity of enzymes for their respective substrates has been a focal point of enzyme kinetics since the initial characterization of metabolic chemistry. Various processes to quantify an enzyme's specificity using kinetics have been utilized over the decades. Fersht's definition of the ratio kcat/Km for two different substrates as the "specificity constant" (ref [7]), based on the premise that the important specificity existed when the substrates were competing in the same reaction, has become a consensus standard for enzymes obeying Michaelis-Menten kinetics. The expansion of the theory for the determination of the relative specificity constants for a very large number of competing substrates, e.g. those present in a combinatorial library, in a single reaction mixture has been developed in this contribution. The ratio of kcat/Km for isotopologs has also become a standard in mechanistic enzymology where kinetic isotope effects have been measured by the development of internal competition experiments with extreme precision. This contribution extends the theory of kinetic isotope effects to internal competition between three isotopologs present at non-tracer concentrations in the same reaction mix. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment. Published by Elsevier B.V.

  7. Substrate system for spray forming

    DOEpatents

    Chu, Men G.; Chernicoff, William P.

    2002-01-01

    A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

  8. Substrate system for spray forming

    DOEpatents

    Chu, Men G.; Chernicoff, William P.

    2000-01-01

    A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

  9. Nitrification in a zeoponic substrate.

    PubMed

    McGilloway, R L; Weaver, R W; Ming, D W; Gruener, J E

    2003-10-01

    Clinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material. The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate. Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates. Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria. In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.). The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate. Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1. Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1. Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take. Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity.

  10. Nitrification in a zeoponic substrate

    NASA Technical Reports Server (NTRS)

    McGilloway, R. L.; Weaver, R. W.; Ming, D. W.; Gruener, J. E.

    2003-01-01

    Clinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material. The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate. Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates. Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria. In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.). The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate. Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1. Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1. Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take. Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity.

  11. Insulin-like growth factor-binding protein-7 (IGFBP7) transcript: A-to-I editing events in normal and cancerous human keratinocytes.

    PubMed

    Hochberg, Malka; Gilead, Leon; Markel, Gal; Nemlich, Yael; Feiler, Yulia; Enk, Claes David; Denichenko, Polina; Karni, Rotem; Ingber, Arieh

    2013-08-01

    Non-melanoma skin cancers (NMSC) are the most common malignancies in caucasians worldwide. Insulin-like growth factor-binding protein-7 (IGFBP7) was suggested to function as a tumor suppressor gene in several cancers, and to play a role in the proliferation of keratinocytes. A-to-I RNA editing is a post-transcriptional mechanism frequently used to expand and diversify transcriptome and proteome repertoire in eukaryotic cells. A-to-I RNA editing can alter codons, substitute amino acids and affect protein sequence, structure, and function. Two editing sites were identified within the IGFBP7 transcript. To evaluate the expression and editing of IGFBP7 mRNA in NMSC compared to normal epidermis. We examined the expression and mRNA editing level of IGFBP7 in 22 basal cell carcinoma (BCC), 15 squamous cell carcinoma (SCC), and 18 normal epidermis samples that were surgically removed from patients by the Mohs Micrographic Surgery procedure. We studied the effect of IGFBP7 editing on an immortalized HaCaT keratinocyte cell model. IGFBP7 mRNA is over expressed in BCC and SCC compared to normal epidermis. Moreover, the IGFBP7 transcript is highly edited in normal epidermis, but its editing is significantly reduced in BCC and SCC. The edited form of IGFBP7 can inhibit proliferation and induce senescence in cultured keratinocytes. This study describes for the first time A-to-I editing in the coding sequence of a tumor suppressor gene in humans, and suggests that IGFBP7 editing serves as a fine-tuning mechanism to maintain the equilibrium between proliferation and senescence in normal skin.

  12. Dewetting on microstructured substrates

    NASA Astrophysics Data System (ADS)

    Kim, Taehong; Kim, Wonjung

    2016-11-01

    A thin liquid film has an equilibrium thickness in such a way as to minimize the free energy. When a liquid film thickness is out of its equilibrium, the film seeks its equilibrium state, resulting in dynamics of liquid film, which are referred to as wetting and dewetting, depending on the flow direction. We here present a combined experimental and theoretical investigation of dewetting on a substrate with parallel microstructures. Our experiments show that residue may remain on the substrate after dewetting, and residue morphologies can be classified into three modes. Based on our experimental observations, we elucidate how the modes depend on the pattern morphology and contact angle, and develop a model for the contact line motion. Our results provide a basis for controlling the thickness film, which is important for many practical applications such as oil recovery, detergency, lithography, and cleaning. This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No.2015R1A2A2A04006181).

  13. Maintainable substrate carrier for electroplating

    DOEpatents

    Chen, Chen-An [Milpitas, CA; Abas, Emmanuel Chua [Laguna, PH; Divino, Edmundo Anida [Cavite, PH; Ermita, Jake Randal G [Laguna, PH; Capulong, Jose Francisco S [Laguna, PH; Castillo, Arnold Villamor [Batangas, PH; Ma,; Xiaobing, Diana [Saratoga, CA

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  14. Maintainable substrate carrier for electroplating

    DOEpatents

    Chen, Chen-An; Abas, Emmanuel Chua; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor; Ma, Diana Xiaobing

    2016-08-02

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  15. A-to-I RNA editing occurs at over a hundred million genomic sites, located in a majority of human genes.

    PubMed

    Bazak, Lily; Haviv, Ami; Barak, Michal; Jacob-Hirsch, Jasmine; Deng, Patricia; Zhang, Rui; Isaacs, Farren J; Rechavi, Gideon; Li, Jin Billy; Eisenberg, Eli; Levanon, Erez Y

    2014-03-01

    RNA molecules transmit the information encoded in the genome and generally reflect its content. Adenosine-to-inosine (A-to-I) RNA editing by ADAR proteins converts a genomically encoded adenosine into inosine. It is known that most RNA editing in human takes place in the primate-specific Alu sequences, but the extent of this phenomenon and its effect on transcriptome diversity are not yet clear. Here, we analyzed large-scale RNA-seq data and detected ∼1.6 million editing sites. As detection sensitivity increases with sequencing coverage, we performed ultradeep sequencing of selected Alu sequences and showed that the scope of editing is much larger than anticipated. We found that virtually all adenosines within Alu repeats that form double-stranded RNA undergo A-to-I editing, although most sites exhibit editing at only low levels (<1%). Moreover, using high coverage sequencing, we observed editing of transcripts resulting from residual antisense expression, doubling the number of edited sites in the human genome. Based on bioinformatic analyses and deep targeted sequencing, we estimate that there are over 100 million human Alu RNA editing sites, located in the majority of human genes. These findings set the stage for exploring how this primate-specific massive diversification of the transcriptome is utilized.

  16. A Novel Computational Strategy to Identify A-to-I RNA Editing Sites by RNA-Seq Data: De Novo Detection in Human Spinal Cord Tissue

    PubMed Central

    Picardi, Ernesto; Gallo, Angela; Galeano, Federica; Tomaselli, Sara; Pesole, Graziano

    2012-01-01

    RNA editing is a post-transcriptional process occurring in a wide range of organisms. In human brain, the A-to-I RNA editing, in which individual adenosine (A) bases in pre-mRNA are modified to yield inosine (I), is the most frequent event. Modulating gene expression, RNA editing is essential for cellular homeostasis. Indeed, its deregulation has been linked to several neurological and neurodegenerative diseases. To date, many RNA editing sites have been identified by next generation sequencing technologies employing massive transcriptome sequencing together with whole genome or exome sequencing. While genome and transcriptome reads are not always available for single individuals, RNA-Seq data are widespread through public databases and represent a relevant source of yet unexplored RNA editing sites. In this context, we propose a simple computational strategy to identify genomic positions enriched in novel hypothetical RNA editing events by means of a new two-steps mapping procedure requiring only RNA-Seq data and no a priori knowledge of RNA editing characteristics and genomic reads. We assessed the suitability of our procedure by confirming A-to-I candidates using conventional Sanger sequencing and performing RNA-Seq as well as whole exome sequencing of human spinal cord tissue from a single individual. PMID:22957051

  17. ADARs: allies or enemies? The importance of A-to-I RNA editing in human disease: from cancer to HIV-1.

    PubMed

    Gallo, Angela; Locatelli, Franco

    2012-02-01

    Adenosine deaminases acting on RNA (ADARs) are enzymes that convert adenosine (A) to inosine (I) in nuclear-encoded RNAs and viral RNAs. The activity of ADARs has been demonstrated to be essential in mammals and serves to fine-tune different proteins and modulate many molecular pathways. Recent findings have shown that ADAR activity is altered in many pathological tissues. Moreover, it has been shown that modulation of RNA editing is important for cell proliferation and migration, and has a protective effect on ischaemic insults. This review summarises available recent knowledge on A-to-I RNA editing and ADAR enzymes, with particular attention given to the emerging role played by these enzymes in cancer, some infectious diseases and immune-mediated disorders.

  18. PLZT capacitor on glass substrate

    DOEpatents

    Fairchild, Manuel Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine Wk; Ma, Beihai; Balachandran, Uthamalingam

    2016-03-29

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  19. PLZT capacitor on glass substrate

    DOEpatents

    Fairchild, M. Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine W. K.; Ma, Beihai; Balachandran, Uthamalingam

    2016-01-05

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  20. Sealed substrate carrier for electroplating

    DOEpatents

    Ganti, Kalyana Bhargava [Fremont, CA

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier includes a non-conductive carrier body on which the substrates are held, and conductive lines are embedded within the carrier body. A conductive bus bar is embedded into a top side of the carrier body and is conductively coupled to the conductive lines. A thermoplastic overmold covers a portion of the bus bar, and there is a plastic-to-plastic bond between the thermoplastic overmold and the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  1. Pedestal substrate for coated optics

    DOEpatents

    Hale, Layton C.; Malsbury, Terry N.; Patterson, Steven R.

    2001-01-01

    A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

  2. Graphene: Substrate preparation and introduction.

    PubMed

    Pantelic, Radosav S; Suk, Ji Won; Magnuson, Carl W; Meyer, Jannik C; Wachsmuth, Philipp; Kaiser, Ute; Ruoff, Rodney S; Stahlberg, Henning

    2011-04-01

    This technical note describes the transfer of continuous, single-layer, pristine graphene to standard Quantifoil TEM grids. We compare the transmission properties of pristine graphene substrates to those of graphene oxide and thin amorphous carbon substrates. Positively stained DNA imaged across amorphous carbon is typically indiscernible and requires metal shadowing for sufficient contrast. However, in a practical illustration of the new substrates properties, positively stained DNA is imaged across pristine graphene in striking contrast without the need of metal shadowing. We go onto discuss technical considerations and the potential applications of pristine graphene substrates as well as their ongoing development.

  3. Carbon nanotubes on a substrate

    DOEpatents

    Gao, Yufei [Kennewick, WA; Liu, Jun [West Richland, WA

    2002-03-26

    The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

  4. Photoresist substrate having robust adhesion

    DOEpatents

    Dentinger, Paul M.

    2005-07-26

    A substrate material for LIGA applications w hose general composition is Ti/Cu/Ti/SiO.sub.2. The SiO.sub.2 is preferably applied to the Ti/Cu/Ti wafer as a sputtered coating, typically about 100 nm thick. This substrate composition provides improved adhesion for epoxy-based photoresist materials, and particularly the photoresist material SU-8.

  5. Substrate With Low Secondary Emissions

    NASA Technical Reports Server (NTRS)

    Jensen, Kenneth A. (Inventor); Curren, Arthur N. (Inventor); Roman, Robert F. (Inventor)

    2000-01-01

    The present invention is directed to a method and apparatus for producing a highly -textured surface on a copper substrate -with only extremely small amounts of texture-inducing seeding or masking material. The texture-inducing seeding material is delivered to the copper substrate electrically switching the seeding material in and out of a circuit loop.

  6. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, B.; Bolstad, J.J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the present invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process. 4 figs.

  7. Electrospray Ionization on Solid Substrates

    PubMed Central

    So, Pui-Kin; Hu, Bin; Yao, Zhong-Ping

    2014-01-01

    Development of electrospray ionization on solid substrates (solid-substrate ESI) avoids the clogging problem encountered in conventional capillary-based ESI, allows more convenient sampling and permits new applications. So far, solid-substrate ESI with various materials, e.g., metals, paper, wood, fibers and biological tissue, has been developed, and applications ranging from analysis of pure compounds to complex mixtures as well as in vivo study were demonstrated. Particularly, the capability of solid-substrate ESI in direct analysis of complex samples, e.g., biological fluids and foods, has significantly facilitated mass spectrometric analysis in real-life applications and led to increasingly important roles of these techniques nowadays. In this review, various solid-substrate ESI techniques and their applications are summarized and the prospects in this field are discussed. PMID:26819900

  8. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, Bora; Bolstad, James J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the pesent invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process.

  9. The dsRBP and inactive editor ADR-1 utilizes dsRNA binding to regulate A-to-I RNA editing across the C. elegans transcriptome.

    PubMed

    Washburn, Michael C; Kakaradov, Boyko; Sundararaman, Balaji; Wheeler, Emily; Hoon, Shawn; Yeo, Gene W; Hundley, Heather A

    2014-02-27

    Inadequate adenosine-to-inosine editing of noncoding regions occurs in disease but is often uncorrelated with ADAR levels, underscoring the need to study deaminase-independent control of editing. C. elegans have two ADAR proteins, ADR-2 and the theoretically catalytically inactive ADR-1. Using high-throughput RNA sequencing of wild-type and adr mutant worms, we expand the repertoire of C. elegans edited transcripts over 5-fold and confirm that ADR-2 is the only active deaminase in vivo. Despite lacking deaminase function, ADR-1 affects editing of over 60 adenosines within the 3' UTRs of 16 different mRNAs. Furthermore, ADR-1 interacts directly with ADR-2 substrates, even in the absence of ADR-2, and mutations within its double-stranded RNA (dsRNA) binding domains abolish both binding and editing regulation. We conclude that ADR-1 acts as a major regulator of editing by binding ADR-2 substrates in vivo. These results raise the possibility that other dsRNA binding proteins, including the inactive human ADARs, regulate RNA editing through deaminase-independent mechanisms.

  10. The absence of A-to-I editing in the anticodon of plant cytoplasmic tRNAArgACG demands a relaxation of the wobble decoding rules

    PubMed Central

    Aldinger, Carolin A.; Leisinger, Anne-Katrin; Gaston, Kirk W.; Limbach, Patrick A.; Igloi, Gabor L.

    2012-01-01

    It is a prevalent concept that, in line with the Wobble Hypothesis, those tRNAs having an adenosine in the first position of the anticodon become modified to an inosine at this position. Sequencing the cDNA derived from the gene coding for cytoplasmic tRNAArgACG from several higher plants as well as mass spectrometric analysis of the isoacceptor has revealed that for this kingdom an unmodified A in the wobble position of the anticodon is the rule rather than the exception. In vitro translation shows that in the plant system the absence of inosine in the wobble position of tRNAArg does not prevent decoding. This isoacceptor belongs to the class of tRNA that is imported from the cytoplasm into the mitochondria of higher plants. Previous studies on the mitochondrial tRNA pool have demonstrated the existence of tRNAArgICG in this organelle. In moss the mitochondrial encoded distinct tRNAArgACG isoacceptor possesses the I34 modification. The implication is that for mitochondrial protein biosynthesis A-to-I editing is necessary and occurs by a mitochondrion-specific deaminase after import of the unmodified nuclear encoded tRNAArgACG. PMID:22922796

  11. The absence of A-to-I editing in the anticodon of plant cytoplasmic tRNA (Arg) ACG demands a relaxation of the wobble decoding rules.

    PubMed

    Aldinger, Carolin A; Leisinger, Anne-Katrin; Gaston, Kirk W; Limbach, Patrick A; Igloi, Gabor L

    2012-10-01

    It is a prevalent concept that, in line with the Wobble Hypothesis, those tRNAs having an adenosine in the first position of the anticodon become modified to an inosine at this position. Sequencing the cDNA derived from the gene coding for cytoplasmic tRNA (Arg) ACG from several higher plants as well as mass spectrometric analysis of the isoacceptor has revealed that for this kingdom an unmodified A in the wobble position of the anticodon is the rule rather than the exception. In vitro translation shows that in the plant system the absence of inosine in the wobble position of tRNA (Arg) does not prevent decoding. This isoacceptor belongs to the class of tRNA that is imported from the cytoplasm into the mitochondria of higher plants. Previous studies on the mitochondrial tRNA pool have demonstrated the existence of tRNA (Arg) ICG in this organelle. In moss the mitochondrial encoded distinct tRNA (Arg) ACG isoacceptor possesses the I34 modification. The implication is that for mitochondrial protein biosynthesis A-to-I editing is necessary and occurs by a mitochondrion-specific deaminase after import of the unmodified nuclear encoded tRNA (Arg) ACG.

  12. Sizing up soft substrate laminates

    NASA Astrophysics Data System (ADS)

    Woermbke, J. D.; Derencz, R. J.

    1985-02-01

    The basic performance parameters of several soft substrates for microwave and RF circuitry were evaluated experimentally with some custom built resonators. The trials were run with high and low dielectric constant substrates to quantify their variability over a wide range of operating temperatures. The low dielectric constant substrates were made of polytetrafluoroethylene (PTFE) loaded with either chopped or microfiber glass filler. The material was hot-pressed between a thin copper foil sheet and thick Al ground sheet. The high dielectric constant substrates were impregnated with a TiO2 ceramic powder. Tests measured insertion losses in 50 ohm lines from 1-18 GHz and the Q and dielectric constant at 3 GHz with half-wave resonators. The resonators were formed on the substrates with various conditioning treatments and were also examined for adhesion strength. The adhesion did not degrade until heated past 150 C. The substrate properties remained intact after numerous thermal cycles up to 250 C. High dielectric constant soft substrates did maintain good contact with the Cu foil up to 250 C.

  13. Method of processing a substrate

    DOEpatents

    Babayan, Steven E.; Hicks, Robert F.

    2008-02-12

    The invention is embodied in a plasma flow device or reactor having a housing that contains conductive electrodes with openings to allow gas to flow through or around them, where one or more of the electrodes are powered by an RF source and one or more are grounded, and a substrate or work piece is placed in the gas flow downstream of the electrodes, such that said substrate or work piece is substantially uniformly contacted across a large surface area with the reactive gases emanating therefrom. The invention is also embodied in a plasma flow device or reactor having a housing that contains conductive electrodes with openings to allow gas to flow through or around them, where one or more of the electrodes are powered by an RF source and one or more are grounded, and one of the grounded electrodes contains a means of mixing in other chemical precursors to combine with the plasma stream, and a substrate or work piece placed in the gas flow downstream of the electrodes, such that said substrate or work piece is contacted by the reactive gases emanating therefrom. In one embodiment, the plasma flow device removes organic materials from a substrate or work piece, and is a stripping or cleaning device. In another embodiment, the plasma flow device kills biological microorganisms on a substrate or work piece, and is a sterilization device. In another embodiment, the plasma flow device activates the surface of a substrate or work piece, and is a surface activation device. In another embodiment, the plasma flow device etches materials from a substrate or work piece, and is a plasma etcher. In another embodiment, the plasma flow device deposits thin films onto a substrate or work piece, and is a plasma-enhanced chemical vapor deposition device or reactor.

  14. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, Richard K.; Bystroff, Roman I.; Miller, Dale E.

    1987-01-01

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  15. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, R.K.; Bystroff, R.I.; Miller, D.E.

    1986-08-27

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  16. Direct cooled power electronics substrate

    DOEpatents

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Lowe, Kirk T [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  17. Region-specific alterations of A-to-I RNA editing of serotonin 2c receptor in the cortex of suicides with major depression

    PubMed Central

    Weissmann, D; van der Laan, S; Underwood, M D; Salvetat, N; Cavarec, L; Vincent, L; Molina, F; Mann, J J; Arango, V; Pujol, J F

    2016-01-01

    Brain region-specific abnormalities in serotonergic transmission appear to underlie suicidal behavior. Alterations of RNA editing on the serotonin receptor 2C (HTR2C) pre-mRNA in the brain of suicides produce transcripts that attenuate 5-HT2CR signaling by impairing intracellular G-protein coupling and subsequent intracellular signal transduction. In brain, the distribution of RNA-editing enzymes catalyzing deamination (A-to-I modification) shows regional variation, including within the cerebral cortex. We tested the hypothesis that altered pre-mRNA 5-HT2CR receptor editing in suicide is region-specific. To this end, we investigated the complete 5-HT2CR mRNA-editing profile in two architectonically distinct cortical areas involved in mood regulation and decision-making in a clinically well-characterized cohort of age- and sex-matched non-psychiatric drug-free controls and depressed suicides. By using an original biochemical detection method, that is, capillary electrophoresis single-stranded conformational polymorphism (CE-SSCP), we corroborated the 5-HT2CR mRNA-editing profile previously described in the dorsolateral prefrontal cortex (Brodmann area 9 (BA9)). Editing of 5-HT2CR mRNA displayed clear regional difference when comparing dorsolateral prefrontal cortex (BA9) and anterior cingulate cortex (BA24). Compared with non-psychiatric control individuals, alterations of editing levels of 5-HT2CR mRNA were detected in both cortical areas of depressed suicides. A marked increase in editing on 5-HT2CR was especially observed in the anterior cingulate cortex in suicides, implicating this cortical area in suicide risk. The results suggest that region-specific changes in RNA editing of 5-HT2CR mRNA and deficient receptor function likely contribute to the etiology of major depressive disorder or suicide. PMID:27576167

  18. Bitumen production and substrate stimulation

    SciTech Connect

    Mims, D. S.

    1985-04-16

    A well completion, having an injection end and a recovery end, and method for recovering heavy hydrocarbons or bitumen from a subterranean formation. The completion includes a well liner which lies in a generally horizontal disposition within a hydrocarbon holding substrate. Means for carrying a stream of a hot stimulating fluid from the well's injection end such that said fluid will migrate into the substrate surrounding the liner. A fluid impervious barrier is movably positioned within the well liner between the injection end and the production end thereof, and prompts establishment of a pressure differential across the said barrier. The barrier urges pressurized stimulating agent outwardly into the substrate, thereby creating a heated path along which the bitumen emulsion flows toward the well's lower pressure production end. The barrier is adapted to be repositioned within the liner to adjust the bitumen flow path through the substrate.

  19. Film Growth on Nanoporous Substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Joy, James; Zhao, Chenwei; Xu, J. M.; Valles, James

    Self-ordered nanoporous anodic aluminum oxide (AAO) provides an easy way to fabricate nano structured material, such as nano wires and nano particles. We employ AAO as substrates and focus on the thermally evaporated film growth on the surface of the substrate. With various materials deposited onto the substrate, we find the films show different structures, e,g. ordered array of nano particles for Lead and nanohoneycomb structure for Silver. We relate the differing behaviors to the difference of surface energy and diffusion constant. To verify this, the effect of substrate temperature on the film growth has been explored and the structure of the film has been successfully changed through the process. We are grateful for the support of NSF Grants No. DMR-1307290.

  20. Substrate channeling in proline metabolism

    PubMed Central

    Arentson, Benjamin W.; Sanyal, Nikhilesh; Becker, Donald F.

    2012-01-01

    Proline metabolism is an important pathway that has relevance in several cellular functions such as redox balance, apoptosis, and cell survival. Results from different groups have indicated that substrate channeling of proline metabolic intermediates may be a critical mechanism. One intermediate is pyrroline-5-carboxylate (P5C), which upon hydrolysis opens to glutamic semialdehyde (GSA). Recent structural and kinetic evidence indicate substrate channeling of P5C/GSA occurs in the proline catabolic pathway between the proline dehydrogenase and P5C dehydrogenase active sites of bifunctional proline utilization A (PutA). Substrate channeling in PutA is proposed to facilitate the hydrolysis of P5C to GSA which is unfavorable at physiological pH. The second intermediate, gamma-glutamyl phosphate, is part of the proline biosynthetic pathway and is extremely labile. Substrate channeling of gamma-glutamyl phosphate is thought to be necessary to protect it from bulk solvent. Because of the unfavorable equilibrium of P5C/GSA and the reactivity of gamma-glutamyl phosphate, substrate channeling likely improves the efficiency of proline metabolism. Here, we outline general strategies for testing substrate channeling and review the evidence for channeling in proline metabolism. PMID:22201749

  1. Microstrip antenna on tunable substrate

    NASA Astrophysics Data System (ADS)

    Jose, K. A.; Varadan, Vijay K.; Varadan, Vasundara V.; Mohanan, P.

    1995-05-01

    The tunable patch antenna configurations are becoming popular and attractive in many aspects. This was mainly due to the advent of ferrite thin film technology and tunable substrate materials. The integration of monolithic microwave circuits and antennas are becoming easy today. In the development of magnetic tuning of microstrip patch on ferrite substrate is presented by Rainville and Harackewiez. Radiation characteristics of such antennas are presented by Pozer. Band width and radiation characteristics of such tunable antennas are measured and compared. Usually the substrate losses are considered in the analysis and metallization losses are assumed to be ideal. The analysis of magnetic tunable radiator including metallization and ferrite substrate losses are presented. However, all such tuning and integration of circuits and antennas are mainly on ferrite substrate due to magnetic tuning. Recently, Varadan et al. established that the BaxSr1-xTiO3 series ferroelectric materials such as Barium Strontium Titanate (BST) are well suited for microwave phase shifter applications. It could be possible to change the dielectric constant of these materials more than 50% depending on the BST composition, by changing the applied bias voltage. Also, the porosity of BST can be controlled during processing to produce dielectric constants in the range of 15 to 1500, with some trade off in tunability. In this paper, we are presenting the possibility of designing a microstrip patch antenna on such tunable substrate. Such antennas are having the major advantage of electronic tunability and compact size.

  2. PREFACE: Cell-substrate interactions Cell-substrate interactions

    NASA Astrophysics Data System (ADS)

    Gardel, Margaret; Schwarz, Ulrich

    2010-05-01

    One of the most striking achievements of evolution is the ability to build cellular systems that are both robust and dynamic. Taken by themselves, both properties are obvious requirements: robustness reflects the fact that cells are there to survive, and dynamics is required to adapt to changing environments. However, it is by no means trivial to understand how these two requirements can be implemented simultaneously in a physical system. The long and difficult quest to build adaptive materials is testimony to the inherent difficulty of this goal. Here materials science can learn a lot from nature, because cellular systems show that robustness and dynamics can be achieved in a synergetic fashion. For example, the capabilities of tissues to repair and regenerate are still unsurpassed in the world of synthetic materials. One of the most important aspects of the way biological cells adapt to their environment is their adhesive interaction with the substrate. Numerous aspects of the physiology of metazoan cells, including survival, proliferation, differentiation and migration, require the formation of adhesions to the cell substrate, typically an extracellular matrix protein. Adhesions guide these diverse processes both by mediating force transmission from the cell to the substrate and by controlling biochemical signaling pathways. While the study of cell-substrate adhesions is a mature field in cell biology, a quantitative biophysical understanding of how the interactions of the individual molecular components give rise to the rich dynamics and mechanical behaviors observed for cell-substrate adhesions has started to emerge only over the last decade or so. The recent growth of research activities on cell-substrate interactions was strongly driven by the introduction of new physical techniques for surface engineering into traditional cell biological work with cell culture. For example, microcontact printing of adhesive patterns was used to show that cell fate depends

  3. Mapping protease substrates using a biotinylated phage substrate library.

    SciTech Connect

    Scholle, M. D.; Kriplani, U.; Pabon, A.; Sishtla, K.; Glucksman, M. J.; Kay, B. K.; Biosciences Division; Chicago Medical School

    2005-05-05

    We describe a bacteriophage M13 substrate library encoding the AviTag (BirA substrate) and combinatorial heptamer peptides displayed at the N terminus of the mature form of capsid protein III. Phages are biotinylated efficiently (> or = 50%) when grown in E. coli cells coexpressing BirA, and such viral particles can be immobilized on a streptavidin-coated support and released by protease cleavage within the combinatorial peptide. We have used this library to map the specificity of human Factor Xa and a neuropeptidase, neurolysin (EC3.4.24.16). Validation by analysis of isolated peptide substrates has revealed that neurolysin recognizes the motif hydrophobic-X-Pro-Arg-hydrophobic, where Arg-hydrophobic is the scissile bond.

  4. Mapping protease substrates by using a biotinylated phage substrate library.

    PubMed

    Scholle, Michael D; Kriplani, Ushma; Pabon, Amanda; Sishtla, Kamakshi; Glucksman, Marc J; Kay, Brian K

    2006-05-01

    We describe a bacteriophage M13 substrate library encoding the AviTag (BirA substrate) and combinatorial heptamer peptides displayed at the N terminus of the mature form of capsid protein III. Phages are biotinylated efficiently (> or = 50%) when grown in E. coli cells coexpressing BirA, and such viral particles can be immobilized on a streptavidin-coated support and released by protease cleavage within the combinatorial peptide. We have used this library to map the specificity of human Factor Xa and a neuropeptidase, neurolysin (EC3.4.24.16). Validation by analysis of isolated peptide substrates has revealed that neurolysin recognizes the motif hydrophobic-X-Pro-Arg-hydrophobic, where Arg-hydrophobic is the scissile bond.

  5. Substrate curvature regulates cell migration

    NASA Astrophysics Data System (ADS)

    He, Xiuxiu; Jiang, Yi

    2017-06-01

    Cell migration is essential in many aspects of biology. Many basic migration processes, including adhesion, membrane protrusion and tension, cytoskeletal polymerization, and contraction, have to act in concert to regulate cell migration. At the same time, substrate topography modulates these processes. In this work, we study how substrate curvature at micrometer scale regulates cell motility. We have developed a 3D mechanical model of single cell migration and simulated migration on curved substrates with different curvatures. The simulation results show that cell migration is more persistent on concave surfaces than on convex surfaces. We have further calculated analytically the cell shape and protrusion force for cells on curved substrates. We have shown that while cells spread out more on convex surfaces than on concave ones, the protrusion force magnitude in the direction of migration is larger on concave surfaces than on convex ones. These results offer a novel biomechanical explanation to substrate curvature regulation of cell migration: geometric constrains bias the direction of the protrusion force and facilitates persistent migration on concave surfaces.

  6. Substrate curvature regulates cell migration.

    PubMed

    He, Xiuxiu; Jiang, Yi

    2017-05-23

    Cell migration is essential in many aspects of biology. Many basic migration processes, including adhesion, membrane protrusion and tension, cytoskeletal polymerization, and contraction, have to act in concert to regulate cell migration. At the same time, substrate topography modulates these processes. In this work, we study how substrate curvature at micrometer scale regulates cell motility. We have developed a 3D mechanical model of single cell migration and simulated migration on curved substrates with different curvatures. The simulation results show that cell migration is more persistent on concave surfaces than on convex surfaces. We have further calculated analytically the cell shape and protrusion force for cells on curved substrates. We have shown that while cells spread out more on convex surfaces than on concave ones, the protrusion force magnitude in the direction of migration is larger on concave surfaces than on convex ones. These results offer a novel biomechanical explanation to substrate curvature regulation of cell migration: geometric constrains bias the direction of the protrusion force and facilitates persistent migration on concave surfaces.

  7. Coatings on reflective mask substrates

    SciTech Connect

    Tong, William Man-Wai; Taylor, John S.; Hector, Scott D.; Mangat, Pawitter J. S.; Stivers, Alan R.; Kofron, Patrick G.; Thompson, Matthew A.

    2002-01-01

    A process for creating a mask substrate involving depositing: 1) a coating on one or both sides of a low thermal expansion material EUVL mask substrate to improve defect inspection, surface finishing, and defect levels; and 2) a high dielectric coating, on the backside to facilitate electrostatic chucking and to correct for any bowing caused by the stress imbalance imparted by either other deposited coatings or the multilayer coating of the mask substrate. An film, such as TaSi, may be deposited on the front side and/or back of the low thermal expansion material before the material coating to balance the stress. The low thermal expansion material with a silicon overlayer and a silicon and/or other conductive underlayer enables improved defect inspection and stress balancing.

  8. Porous substrates filled with nanomaterials

    DOEpatents

    Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.; Stadermann, Michael

    2014-08-19

    A composition comprising: at least one porous carbon monolith, such as a carbon aerogel, comprising internal pores, and at least one nanomaterial, such as carbon nanotubes, disposed uniformly throughout the internal pores. The nanomaterial can be disposed in the middle of the monolith. In addition, a method for making a monolithic solid with both high surface area and good bulk electrical conductivity is provided. A porous substrate having a thickness of 100 microns or more and comprising macropores throughout its thickness is prepared. At least one catalyst is deposited inside the porous substrate. Subsequently, chemical vapor deposition is used to uniformly deposit a nanomaterial in the macropores throughout the thickness of the porous substrate. Applications include electrical energy storage, such as batteries and capacitors, and hydrogen storage.

  9. Nanostructured Substrates for Optical Sensing

    PubMed Central

    Kemling, Jonathan W.; Qavi, Abraham J.; Bailey, Ryan C.

    2011-01-01

    Sensors that change color have the advantages of versatility, ease of use, high sensitivity, and low cost. The recent development of optically based chemical sensing platforms has increasingly employed substrates manufactured with advanced processing or fabrication techniques to provide precise control over shape and morphology of the sensor micro- and nano-structure. New sensors have resulted with improved capabilities for a number of sensing applications, including the detection of biomolecules and environmental monitoring. This perspective focuses on recent optical sensor devices that utilize nanostructured substrates. PMID:22174955

  10. Replicated CdTe Substrates.

    DTIC Science & Technology

    1983-09-01

    2423/01/72 Watertown, MA 02172 11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Materials Lab (AFWAL/I4LPO) Sept. 1983 Wright Patterson APB...unsuccessful. Using the same technique utilized at Lincoln Labs i.e., baking the resist coated substrates in air at elevated temperatures, carbonization was...the effect of substrate orientation on the lateral to vertical growth rate of the films. Previous work at Lincoln Labs using GaAs and InP had shown a

  11. Cation exchange capacity of pine bark substrates

    USDA-ARS?s Scientific Manuscript database

    Cation exchange capacity (CEC) is an important soil and substrate chemical property. It describes a substrate's ability to retain cation nutrients. Higher CEC values for a substrate generally result in greater amounts of nutrients retained in the substrate and available for plant uptake, and great...

  12. Semiconductor films on flexible iridium substrates

    DOEpatents

    Goyal, Amit

    2005-03-29

    A laminate semiconductor article includes a flexible substrate, an optional biaxially textured oxide buffer system on the flexible substrate, a biaxially textured Ir-based buffer layer on the substrate or the buffer system, and an epitaxial layer of a semiconductor. Ir can serve as a substrate with an epitaxial layer of a semiconductor thereon.

  13. Substrate for thin silicon solar cells

    DOEpatents

    Ciszek, Theodore F.

    1998-01-01

    A substrate for a photovoltaic device wherein the substrate is the base upon which photosensitive material is to be grown and the substrate comprises an alloy having boron in a range from 0.1 atomic % of the alloy to 1.3 atomic % of the alloy and the substrate has a resistivity less than 3.times.10.sup.-3 ohm-cm.

  14. Synthetic substrates for enzyme analysis

    DOEpatents

    Bissell, E.R.; Mitchell, A.R.; Pearson, K.W.; Smith, R.E.

    1983-06-14

    Synthetic substrates are provided which may be represented as A-D. The A moiety includes an amino acid, polypeptide, or derivative. The D moiety includes 7-amino coumarin derivatives having an electron withdrawing substituent group at the 3 position carbon or fused between the 3 and 4 position carbons. No Drawings

  15. Flexible substrate for printed wiring

    NASA Technical Reports Server (NTRS)

    Asakura, M.; Yabe, K.; Tanaka, H.; Soda, A.

    1982-01-01

    A very flexible substrate for printed wiring is disclosed which is composed of a blend of phenoxy resin-polyisocyanate-brominated epoxy resin in which the equivalent ration of the functional groups is hydroxyl grouped: isocyanate group: epoxy group = 1:0.2 to 2:0.5 to 3. The product has outstanding solder resistance and is applied to metal without using adhesives.

  16. Enzymatic reactions on immobilised substrates.

    PubMed

    Gray, Christopher J; Weissenborn, Martin J; Eyers, Claire E; Flitsch, Sabine L

    2013-08-07

    This review gives an overview of enzymatic reactions that have been conducted on substrates attached to solid surfaces. Such biochemical reactions have become more important with the drive to miniaturisation and automation in chemistry, biology and medicine. Technical aspects such as choice of solid surface and analytical methods are discussed and examples of enzyme reactions that have been successful on these surfaces are provided.

  17. Sensor Technologies on Flexible Substrates

    NASA Technical Reports Server (NTRS)

    Koehne, Jessica

    2016-01-01

    NASA Ames has developed sensor technologies on flexible substrates integrated into textiles for personalized environment monitoring and human performance evaluation. Current technologies include chemical sensing for gas leak and event monitoring and biological sensors for human health and performance monitoring. Targeted integration include next generation EVA suits and flexible habitats.

  18. Synthetic substrates for enzyme analysis

    DOEpatents

    Bissell, Eugene R.; Mitchell, Alexander R.; Pearson, Karen W.; Smith, Robert E.

    1983-01-01

    Synthetic substrates are provided which may be represented as A-D. The A moiety thereof includes an amino acid, polypeptide, or derivative thereof. The D moiety thereof includes 7-amino coumarin derivatives having an electron withdrawing substituent group at the 3 position carbon or fused between the 3 and 4 position carbons.

  19. Cellulosic Substrates and Challenges Ahead

    USDA-ARS?s Scientific Manuscript database

    The cost of production of butanol (acetone-butanol-ethanol; or ABE) is determined by feedstock prices, fermentation, recovery, by-product credits and the waste water treatment. Along these lines, we have an intensive research program on the use of various agricultural substrates, fermentation strate...

  20. Substrate Specificity of Chlorophyllase 12

    PubMed Central

    McFeeters, Roger F.

    1975-01-01

    Apparent Km and Vmax values were obtained for hydrolysis of methyl and ethyl chlorophyllides a, methyl and ethyl pheophorbide a, and 9-hydroxymethyl pheophorbide a by chlorophyllase from Ailanthus altissima. Analysis of substrate specificity data for chlorophyllase indicates that the presence of a 9-keto group and a methyl alcohol group esterified at the 7-position in chlorophyll derivatives results in maximum binding affinity for substrates. Data on maximum reaction rates indicate that the rate-controlling step of hydrolysis occurs after release of the alcohol from the ester. Probable high affinity chlorophyllase inhibitors can be predicted on the basis of these specificity studies. An improved method for purification of chlorophyllase has been developed. PMID:16659086

  1. Methods of repairing a substrate

    NASA Technical Reports Server (NTRS)

    Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

    2011-01-01

    A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium boride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

  2. Graphene folding on flat substrates

    SciTech Connect

    Chen, Xiaoming; Zhao, Yadong; Ke, Changhong; Zhang, Liuyang; Wang, Xianqiao

    2014-10-28

    We present a combined experimental-theoretical study of graphene folding on flat substrates. The structure and deformation of the folded graphene sheet are experimentally characterized by atomic force microscopy. The local graphene folding behaviors are interpreted based on nonlinear continuum mechanics modeling and molecular dynamics simulations. Our study on self-folding of a trilayer graphene sheet reports a bending stiffness of about 6.57 eV, which is about four times the reported values for monolayer graphene. Our results reveal that an intriguing free sliding phenomenon occurs at the interlayer van der Waals interfaces during the graphene folding process. This work demonstrates that it is a plausible venue to quantify the bending stiffness of graphene based on its self-folding conformation on flat substrates. The findings reported in this work are useful to a better understanding of the mechanical properties of graphene and in the pursuit of its applications.

  3. Neurobiological Substrates of Tourette's Disorder

    PubMed Central

    Bloch, Michael H.; Smith, Megan E.; Larabi, Daouia; Hampson, Michelle

    2010-01-01

    Abstract Objective This article reviews the available scientific literature concerning the neurobiological substrates of Tourette's disorder (TD). Methods The electronic databases of PubMed, ScienceDirect, and PsycINFO were searched for relevant studies using relevant search terms. Results Neuropathological as well as structural and functional neuroimaging studies of TD implicate not only the sensorimotor corticostriatal circuit, but also the limbic and associative circuits as well. Preliminary evidence also points to abnormalities in the frontoparietal network that is thought to maintain adaptive online control. Evidence supporting abnormalities in dopaminergic and noradrenergic neurotransmission remains strong, although the precise mechanisms remain the subject of speculation. Conclusion Structural and functional abnormalities in multiple parallel corticostriatal circuits may underlie the behavioral manifestations of TD and related neuropsychiatric disorders over the course of development. Further longitudinal research is needed to elucidate these neurobiological substrates. PMID:20807062

  4. Cuprate superconductors on titanium substrates

    NASA Astrophysics Data System (ADS)

    Mitterbauer, Christina; Gritzner, Gerhard

    2007-09-01

    The applicability of titanium as substrate material for coated conductors was investigated. Titanium metal was rolled to a thickness of 1 mm and mechanically polished. The titanium sheets were oxidized in air at 1000 °C for 1 h. A dense oxide layer was formed. YBCO superconducting layers were applied to the oxidized titanium surface via screen printing from a suspension in acetone-terpineol. The YBCO layers were characterized by X-ray diffraction and by scanning electron microscopy.

  5. Substrate for silicon solar cells

    SciTech Connect

    Thomas, D.E.

    1982-08-10

    A substrate is made for silicon solar cells by heating a sheet of large-grained silicon steel at a temperature of at least about 1300* C. In an atmosphere of hydrogen and tungsten hexafluo (Or hexachloride) at a partial pressure ratio of hydrogen to tungsten hexafluoride of about 3 to about 6 to deposit an epitaxial layer of tungsten on said sheet of silicon steel. Epitaxial silicon can then be deposited in a conventional manner on the layer of epitaxial tungsten.

  6. Substrate binding modelling in barnase

    NASA Astrophysics Data System (ADS)

    Gordon-Beresford, R.; Coulombeau, C.; Wodak, S.

    1991-10-01

    The mechanism describing the guanine specific hydrolysis by the different microbial endoribonucleases which has been proposed cannot account in barnase (B. amyloliquefaciens) in the case of GpN dinucleotide hydrolysis, the observed preference for N being A≳G≳C≳U. Similarly the much higher activity toward long RNA molecules as compared to dinucleotides is not understood. A possible explanation for these observations is the existence in barnase of secondary substrate binding sites.

  7. Substrate analogues for isoprenoid enzymes

    SciTech Connect

    Stremler, K.E.

    1987-01-01

    Diphosphonate analogues of geranyl diphosphate, resistant to degradation by phosphatases, were found to be alternate substrates for the reaction with farnesyl diphosphate synthetase isolated from avian liver. The difluoromethane analogue was shown to be the better alternate substrate, in agreement with solvolysis results which indicate that the electronegativity of the difluoromethylene unit more closely approximates that of the normal bridging oxygen. The usefulness of the C/sub 10/ difluoro analogue, for detecting low levels of isoprenoid enzymes in the presence of high levels of phosphatase activity, was demonstrated with a cell-free preparation from lemon peel. A series of C/sub 5/ through C/sub 15/ homoallylic and allylic diphosphonates, as well as two 5'-nucleotide diphosphonates, was prepared in high overall yield using the activation-displacement sequence. Radiolabeled samples of several of the allylic diphosphonates were prepared with tritium located at C1. A series of geraniols, stereospecifically deuterated at C1, was prepared. The enantiomeric purities and absolute configurations were determined by derivatization as the mandelate esters for analysis by /sup 1/H NMR. The stereochemistry of the activation-displacement sequence was examined using C1-deuterated substrates.

  8. Carbon Nanotube Patterning on a Metal Substrate

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor)

    2016-01-01

    A CNT electron source, a method of manufacturing a CNT electron source, and a solar cell utilizing a CNT patterned sculptured substrate are disclosed. Embodiments utilize a metal substrate which enables CNTs to be grown directly from the substrate. An inhibitor may be applied to the metal substrate to inhibit growth of CNTs from the metal substrate. The inhibitor may be precisely applied to the metal substrate in any pattern, thereby enabling the positioning of the CNT groupings to be more precisely controlled. The surface roughness of the metal substrate may be varied to control the density of the CNTs within each CNT grouping. Further, an absorber layer and an acceptor layer may be applied to the CNT electron source to form a solar cell, where a voltage potential may be generated between the acceptor layer and the metal substrate in response to sunlight exposure.

  9. 40 CFR 230.20 - Substrate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Chemical Characteristics of the Aquatic Ecosystem § 230.20 Substrate. (a) The substrate of the aquatic ecosystem underlies open waters of the United States and constitutes the surface of wetlands. It consists of...

  10. 40 CFR 230.20 - Substrate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Chemical Characteristics of the Aquatic Ecosystem § 230.20 Substrate. (a) The substrate of the aquatic ecosystem underlies open waters of the United States and constitutes the surface of wetlands. It consists of...

  11. Substrate-associated microfauna. [Water pollution monitoring

    SciTech Connect

    Burton, G.A.; Lazorchak, J.M.

    1982-06-01

    A literature review of the ecology of substrate-associated microfauna is presented. Sampling procedures for these organisms include sieving, extraction, and coring. Microcosms were studied with silica substrates and sedimentary core. Topics discussed included those dealing with fouling communities and colonization of substrates, and the spatial and temporal distribution of substrate-associated microfauna. The toxicity of chlorination, oil spills, insecticide residues and other organic wastes on these attached organisms were also examined.(KRM)

  12. Patterned substrates and methods for nerve regeneration

    DOEpatents

    Mallapragada, Surya K.; Heath, Carole; Shanks, Howard; Miller, Cheryl A.; Jeftinija, Srdija

    2004-01-13

    Micropatterned substrates and methods for fabrication of artificial nerve regeneration conduits and methods for regenerating nerves are provided. Guidance compounds or cells are seeded in grooves formed on the patterned substrate. The substrates may also be provided with electrodes to provide electrical guidance cues to the regenerating nerve. The micropatterned substrates give physical, chemical, cellular and/or electrical guidance cues to promote nerve regeneration at the cellular level.

  13. Substrate for thin silicon solar cells

    DOEpatents

    Ciszek, T.F.

    1998-07-28

    A substrate is described for a photovoltaic device wherein the substrate is the base upon which photosensitive material is to be grown and the substrate comprises an alloy having boron in a range from 0.1 atomic % of the alloy to 1.3 atomic % of the alloy and the substrate has a resistivity less than 3{times}10{sup {minus}3} ohm-cm. 4 figs.

  14. Substrate for silicon solar cells

    SciTech Connect

    Thomas, D.E.

    1983-09-06

    A substrate is made for silicon solar cells by heating a sheet of large-grained silicon steel at a temperature of at least about 1300/sup 0/ C. in an atmosphere of hydrogen and tungsten hexafluoride (or hexachloride) at a partial pressure ratio of hydrogen to tungsten hexafluoride of about 3 to about 6 to deposit an epitaxial layer of tungsten on said sheet of silicon steel. Epitaxial silicon can then be deposited in a conventional manner on the layer of epitaxial tungsten.

  15. Combined plasma/liquid cleaning of substrates

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars

    2003-04-15

    Apparatus and method for cleaning substrates. A substrate is held and rotated by a chuck and an atmospheric pressure plasma jet places a plasma onto predetermined areas of the substrate. Subsequently liquid rinse is sprayed onto the predetermined areas. In one embodiment, a nozzle sprays a gas onto the predetermined areas to assist in drying the predetermined areas when needed.

  16. Synthetic surfaces as models for biomineralization substrates

    SciTech Connect

    Rieke, P.C.; Tarasevich, B.J.; Bentjen, S.B.; Autrey, T.S.; Nelson, D.A.

    1990-01-01

    Polyethylene and oxide substrates were derivatized with functional groups commonly associated with biomineralization substrates. These groups include carboxylate, phosphate, hydroxy, sulfonate, thiol, and amine. Fourier transform infrared spectroscopy and contact angle wetting were used to identify and characterize the products at each step. The efficacy of these groups toward inducing mineralization will be compared with naturally occurring substrates. 10 refs., 5 figs.

  17. A new lime material for container substrates

    USDA-ARS?s Scientific Manuscript database

    The primary component in greenhouse potting substrates is sphagnum peatmoss. Substrate solution pH of non-amended peatmoss ranges from 4.0 to 4.5. Ideal pH for most greenhouse floriculture crops ranges from 5.8 to 6.2. Dolomitic lime is most often used to elevate substrate pH in peatmoss-based me...

  18. Amending pine bark with alternative substrates

    USDA-ARS?s Scientific Manuscript database

    Due to a number of factors, pine bark supplies have significantly decreased over the past few years. While alternative substrates are being evaluated, many growers are asking if these alternative substrates can be used to stretch existing PB supplies. In this study, two alternative substrates, “Cl...

  19. Polycrystalline silicon on tungsten substrates

    NASA Technical Reports Server (NTRS)

    Bevolo, A. J.; Schmidt, F. A.; Shanks, H. R.; Campisi, G. J.

    1979-01-01

    Thin films of electron-beam-vaporized silicon were deposited on fine-grained tungsten substrates under a pressure of about 1 x 10 to the -10th torr. Mass spectra from a quadrupole residual-gas analyzer were used to determine the partial pressure of 13 residual gases during each processing step. During separate silicon depositions, the atomically clean substrates were maintained at various temperatures between 400 and 780 C, and deposition rates were between 20 and 630 A min. Surface contamination and interdiffusion were monitored by in situ Auger electron spectrometry before and after cleaning, deposition, and annealing. Auger depth profiling, X-ray analysis, and SEM in the topographic and channeling modes were utilized to characterize the samples with respect to silicon-metal interface, interdiffusion, silicide formation, and grain size of silicon. The onset of silicide formation was found to occur at approximately 625 C. Above this temperature tungsten silicides were formed at a rate faster than the silicon deposition. Fine-grain silicon films were obtained at lower temperatures.

  20. Polycrystalline silicon on tungsten substrates

    NASA Technical Reports Server (NTRS)

    Bevolo, A. J.; Schmidt, F. A.; Shanks, H. R.; Campisi, G. J.

    1979-01-01

    Thin films of electron-beam-vaporized silicon were deposited on fine-grained tungsten substrates under a pressure of about 1 x 10 to the -10th torr. Mass spectra from a quadrupole residual-gas analyzer were used to determine the partial pressure of 13 residual gases during each processing step. During separate silicon depositions, the atomically clean substrates were maintained at various temperatures between 400 and 780 C, and deposition rates were between 20 and 630 A min. Surface contamination and interdiffusion were monitored by in situ Auger electron spectrometry before and after cleaning, deposition, and annealing. Auger depth profiling, X-ray analysis, and SEM in the topographic and channeling modes were utilized to characterize the samples with respect to silicon-metal interface, interdiffusion, silicide formation, and grain size of silicon. The onset of silicide formation was found to occur at approximately 625 C. Above this temperature tungsten silicides were formed at a rate faster than the silicon deposition. Fine-grain silicon films were obtained at lower temperatures.

  1. Small droplets on superhydrophobic substrates.

    PubMed

    Gross, Markus; Varnik, Fathollah; Raabe, Dierk; Steinbach, Ingo

    2010-05-01

    We investigate the wetting behavior of liquid droplets on rough hydrophobic substrates for the case of droplets that are of comparable size to the surface asperities. Using a simple three-dimensional analytical free-energy model, we have shown in a recent letter [M. Gross, F. Varnik, and D. Raabe, EPL 88, 26002 (2009)] that, in addition to the well-known Cassie-Baxter and Wenzel states, there exists a further metastable wetting state where the droplet is immersed into the texture to a finite depth, yet not touching the bottom of the substrate. Due to this new state, a quasistatically evaporating droplet can be saved from going over to the Wenzel state and instead remains close to the top of the surface. In the present paper, we give an in-depth account of the droplet behavior based on the results of extensive computer simulations and an improved theoretical model. In particular, we show that releasing the assumption that the droplet is pinned at the outer edges of the pillars improves the analytical results for larger droplets. Interestingly, all qualitative aspects, such as the existence of an intermediate minimum and the "reentrant transition," remain unchanged. We also give a detailed description of the evaporation process for droplets of varying sizes. Our results point out the role of droplet size for superhydrophobicity and give hints for achieving the desired wetting properties of technically produced materials.

  2. Textured substrate tape and devices thereof

    DOEpatents

    Goyal, Amit

    2006-08-08

    A method for forming a sharply biaxially textured substrate, such as a single crystal substrate, includes the steps of providing a deformed metal substrate, followed by heating above the secondary recrystallization temperature of the deformed substrate, and controlling the secondary recrystallization texture by either using thermal gradients and/or seeding. The seed is selected to shave a stable texture below a predetermined temperature. The sharply biaxially textured substrate can be formed as a tape having a length of 1 km, or more. Epitaxial articles can be formed from the tapes to include an epitaxial electromagnetically active layer. The electromagnetically active layer can be a superconducting layer.

  3. Phonon scattering in graphene over substrate steps

    SciTech Connect

    Sevinçli, H.; Brandbyge, M.

    2014-10-13

    We calculate the effect on phonon transport of substrate-induced bends in graphene. We consider bending induced by an abrupt kink in the substrate, and provide results for different step-heights and substrate interaction strengths. We find that individual substrate steps reduce thermal conductance in the range between 5% and 47%. We also consider the transmission across linear kinks formed by adsorption of atomic hydrogen at the bends and find that individual kinks suppress thermal conduction substantially, especially at high temperatures. Our analysis show that substrate irregularities can be detrimental for thermal conduction even for small step heights.

  4. Automated cassette-to-cassette substrate handling system

    SciTech Connect

    Kraus, Joseph Arthur; Boyer, Jeremy James; Mack, Joseph; DeChellis, Michael; Koo, Michael

    2014-03-18

    An automated cassette-to-cassette substrate handling system includes a cassette storage module for storing a plurality of substrates in cassettes before and after processing. A substrate carrier storage module stores a plurality of substrate carriers. A substrate carrier loading/unloading module loads substrates from the cassette storage module onto the plurality of substrate carriers and unloads substrates from the plurality of substrate carriers to the cassette storage module. A transport mechanism transports the plurality of substrates between the cassette storage module and the plurality of substrate carriers and transports the plurality of substrate carriers between the substrate carrier loading/unloading module and a processing chamber. A vision system recognizes recesses in the plurality of substrate carriers corresponding to empty substrate positions in the substrate carrier. A processor receives data from the vision system and instructs the transport mechanism to transport substrates to positions on the substrate carrier in response to the received data.

  5. Stiff substrates enhance cultured neuronal network activity.

    PubMed

    Zhang, Quan-You; Zhang, Yan-Yan; Xie, Jing; Li, Chen-Xu; Chen, Wei-Yi; Liu, Bai-Lin; Wu, Xiao-an; Li, Shu-Na; Huo, Bo; Jiang, Lin-Hua; Zhao, Hu-Cheng

    2014-08-28

    The mechanical property of extracellular matrix and cell-supporting substrates is known to modulate neuronal growth, differentiation, extension and branching. Here we show that substrate stiffness is an important microenvironmental cue, to which mouse hippocampal neurons respond and integrate into synapse formation and transmission in cultured neuronal network. Hippocampal neurons were cultured on polydimethylsiloxane substrates fabricated to have similar surface properties but a 10-fold difference in Young's modulus. Voltage-gated Ca(2+) channel currents determined by patch-clamp recording were greater in neurons on stiff substrates than on soft substrates. Ca(2+) oscillations in cultured neuronal network monitored using time-lapse single cell imaging increased in both amplitude and frequency among neurons on stiff substrates. Consistently, synaptic connectivity recorded by paired recording was enhanced between neurons on stiff substrates. Furthermore, spontaneous excitatory postsynaptic activity became greater and more frequent in neurons on stiff substrates. Evoked excitatory transmitter release and excitatory postsynaptic currents also were heightened at synapses between neurons on stiff substrates. Taken together, our results provide compelling evidence to show that substrate stiffness is an important biophysical factor modulating synapse connectivity and transmission in cultured hippocampal neuronal network. Such information is useful in designing instructive scaffolds or supporting substrates for neural tissue engineering.

  6. Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates

    NASA Technical Reports Server (NTRS)

    Simpson, Joycely O. (Inventor); St.Clair, Terry L. (Inventor)

    1999-01-01

    A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers. acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors, in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors. weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 1000 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

  7. Substrate heater for thin film deposition

    DOEpatents

    Foltyn, Steve R.

    1996-01-01

    A substrate heater for thin film deposition of metallic oxides upon a target substrate configured as a disk including means for supporting in a predetermined location a target substrate configured as a disk, means for rotating the target substrate within the support means, means for heating the target substrate within the support means, the heating means about the support means and including a pair of heating elements with one heater element situated on each side of the predetermined location for the target substrate, with one heater element defining an opening through which desired coating material can enter for thin film deposition and with the heating means including an opening slot through which the target substrate can be entered into the support means, and, optionally a means for thermal shielding of the heating means from surrounding environment is disclosed.

  8. Substrate Effects in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Steel, Stephen Chris

    1990-01-01

    The self emptying beaker technique was used to study the superfluid properties of ^3He confined in the van der Waals film adsorbed on the surface of a metal beaker. The experimental cell was designed to minimize thermal gradients along the ^3 He film. In contrast to the results of an earlier experiment by Sachrajda et al, which suggested that film flow occurred at temperatures as high as 3.5 mK (SACH-85), no flow was observed above the bulk transition temperature T_sp{rm c}{rm B} = 0.93 mK. The transition temperatures measured using round rim beakers agreed with theory, giving the predicted normal-superfluid phase boundary 2 delta/xi(T) = pi, where delta is the film thickness and xi(T) is the temperature dependent coherence length. The ^3He film thickness was inferred from Atkins' oscillation measurements of ^4He films on the same substrate. When a ^4He monolayer was adsorbed on the surface of a copper beaker, it suppressed the diffuse scattering of ^3He quasiparticles at the copper wall, an effect first observed by Freeman et al using a mylar substrate (FRMN-88). With the ^4He monolayer in place, there was no measurable suppression of the transition temperature, even for films as thin as 100 nm. This suggests that the ^3 He quasiparticle scattering at the free liquid surface as well as the ^4He covered substrate was specular. This is the first evidence of the nature of the scattering at the free surface. After the ^3He level in the beaker had dropped between 15 and 85 mu m, the flow rate abruptly dropped by a factor to ten or more. This may be associated with the transition between the superfluid B-phase, expected in thick films, and the superfluid A-phase, expected in thin films. The observed critical currents are roughly an order of magnitude smaller than predicted by the pair breaking limit, suggesting some other dissipation mechanism is responsible for limiting the current.

  9. Superhydrophobicity enhancement through substrate flexibility.

    PubMed

    Vasileiou, Thomas; Gerber, Julia; Prautzsch, Jana; Schutzius, Thomas M; Poulikakos, Dimos

    2016-11-22

    Inspired by manifestations in nature, microengineering and nanoengineering of synthetic materials to achieve superhydrophobicity has been the focus of much work. Generally, hydrophobicity is enhanced through the combined effects of surface texturing and chemistry; being durable, rigid materials are the norm. However, many natural and technical surfaces are flexible, and the resulting effect on hydrophobicity has been largely ignored. Here, we show that the rational tuning of flexibility can work synergistically with the surface microtexture or nanotexture to enhance liquid repellency performance, characterized by impalement and breakup resistance, contact time reduction, and restitution coefficient increase. Reduction in substrate areal density and stiffness imparts immediate acceleration and intrinsic responsiveness to impacting droplets (∼350 × g), mitigating the collision and lowering the impalement probability by ∼60% without the need for active actuation. Furthermore, we exemplify the above discoveries with materials ranging from man-made (thin steel or polymer sheets) to nature-made (butterfly wings).

  10. Mosaic of Commemorative Microscope Substrate

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Written by electron beam lithography in the Microdevices Laboratory of NASA's Jet Propulsion Laboratory, this Optical Microscope substrate helps the Phoenix Mars Mission science team learn how to assemble individual microscope images into a mosaic by aligning rows of text.

    Each line is about 0.1 millimeter tall, the average thickness of a human hair. Except for the Mogensen twins, the names are of babies born and team members lost during the original development of MECA (the Microscopy, Electrochemistry and Conductivity Analyzer) for the canceled 2001 Mars lander mission. The plaque also acknowledges the MECA 2001 principal investigator, now retired.

    This image was taken by the MECA Optical Microscope on Sol 111, or the 111th day of the Phoenix mission (Sept. 16, 2008).

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by JPL, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

  11. Mosaic of Commemorative Microscope Substrate

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Written by electron beam lithography in the Microdevices Laboratory of NASA's Jet Propulsion Laboratory, this Optical Microscope substrate helps the Phoenix Mars Mission science team learn how to assemble individual microscope images into a mosaic by aligning rows of text.

    Each line is about 0.1 millimeter tall, the average thickness of a human hair. Except for the Mogensen twins, the names are of babies born and team members lost during the original development of MECA (the Microscopy, Electrochemistry and Conductivity Analyzer) for the canceled 2001 Mars lander mission. The plaque also acknowledges the MECA 2001 principal investigator, now retired.

    This image was taken by the MECA Optical Microscope on Sol 111, or the 111th day of the Phoenix mission (Sept. 16, 2008).

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by JPL, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

  12. Fundamentals of topographic substrate leveling

    SciTech Connect

    Stillwagon, L.E.; Larson, R.G.

    1988-06-01

    The leveling of 100--500-..mu..m-wide, 1-..mu..m-deep isolated holes and trenches on a silicon substrate by 1--3-..mu..m-thick silicone oil films was observed by measuring film thickness changes at the centers of the features using a noncontact, interferometric technique. The dependence of the leveling time t on feature width w, film viscosity eta, and the initial film thickness h/sub 0/ was investigated and compared to theoretical predictions. Experimental data were obtained for various values of w, eta, and h/sub 0/. Except when the film thickness was about 1 ..mu..m, the data for each different type of geometry fell on a single curve when the degree of leveling or planarization was plotted against Tequivalentt..gamma..h/sup 3//sub 0//etaw/sup 4/ where ..gamma.. is the surface tension of the film. At the same value of T, the degree of planarization of isolated holes was about twice that of isolated trenches. The planarization versus T curves should apply to all Newtonian liquids and may be used to predict the degree of planarization that will be achieved at specified leveling times by materials having specified values of eta, h/sub 0/, and ..gamma... Thus, the curves may be useful in selecting planarizing materials for semiconductor fabrication steps that require substrate topography leveling. Simulations of the leveling process based on capillarity-driven flow were performed and agreed well with the experimental data. The simulations predicted some interesting and unexpected behavior that was observed experimentally. At short times the planarization became worse before improving at longer times and bumps appeared in the film profiles that apparently were a first step in minimizing surface energy.

  13. Substrate effect in chemically amplified resist

    NASA Astrophysics Data System (ADS)

    Mori, Shigeyasu; Watanabe, Takeo; Adachi, Kouichirou; Fukushima, Takashi; Uda, Keichiro; Sato, Yuichi

    1996-06-01

    SiN substrate effect in chemically amplified (CA) resist has been investigated by surface analysis and evaluating the pattern profile of CA negative tone resist. Fine profile can be replicated on SiN substrate treated with oxygen plasma optimized condition. Undercut profile can be affected by adsorbed materials on SiN substrate from thermal desorption spectroscopy (TDS) analysis results. From the results of electron spectroscopy for chemical analysis (ESCA), it is found that Si-N bonding is replaced to Si-O bonding while SiN substrate is treated with oxygen plasma. Relations between footing length and oxygen plasma treatment condition suggest that undercut profile due to the concentration of nitrogen on the surface of SiN substrate. At the interface between the SiN substrate and the CA resist, the SiN substrate works as base existing water, and quenches photo-generated-acids. The mechanism of substrate effect of SiN is clarified. Reducing the SiN-substrate effect by treating the surface with oxygen plasma, fine resist pattern without undercut and footing is formed on SiN substrate.

  14. Non-permeable substrate carrier for electroplating

    DOEpatents

    Abas, Emmanuel Chua; Chen, Chen-An; Ma, Diana Xiaobing; Ganti, Kalyana Bhargava

    2012-11-27

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  15. Non-permeable substrate carrier for electroplating

    DOEpatents

    Abas, Emmanuel Chua; Chen, Chen-an; Ma, Diana Xiaobing; Ganti, Kalyana; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor

    2015-12-29

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  16. Substrates For High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.

    1988-01-01

    Proposed hot-dipping process prepares materials well suited to serve as substrates for high-temperature superconductors. Makes it possible to produce substrates combining properties needed for given application, such as flexibility, strength, long grains, and <001> crystal orientation. Properties favor growth of superconductive films carrying high current and fabricated in variety of useful shapes. Used in making solar cells, described in "Hot-Dipped Metal Films as Epitaxial Substrates" (NPO-15904).

  17. Removing bonded skin from a substrate

    NASA Technical Reports Server (NTRS)

    Chartier, E. N.

    1980-01-01

    Metal skin is peeled off like sardine-can cover with key. Method is useful in removing bonded skins from any substrate where substrate is strong enough not to buckle or tear when bonded skin is rolled free. Also, it is useful for removing sections of damaged skin where bladders of other equipment below substrate might be damaged if saw or router were used to cut completely through skin.

  18. Substrate for thin silicon solar cells

    DOEpatents

    Ciszek, Theodore F.

    1995-01-01

    A photovoltaic device for converting solar energy into electrical signals comprises a substrate, a layer of photoconductive semiconductor material grown on said substrate, wherein the substrate comprises an alloy of boron and silicon, the boron being present in a range of from 0.1 to 1.3 atomic percent, the alloy having a lattice constant substantially matched to that of the photoconductive semiconductor material and a resistivity of less than 1.times.10.sup.-3 ohm-cm.

  19. Substrate for thin silicon solar cells

    DOEpatents

    Ciszek, T.F.

    1995-03-28

    A photovoltaic device for converting solar energy into electrical signals comprises a substrate, a layer of photoconductive semiconductor material grown on said substrate, wherein the substrate comprises an alloy of boron and silicon, the boron being present in a range of from 0.1 to 1.3 atomic percent, the alloy having a lattice constant substantially matched to that of the photoconductive semiconductor material and a resistivity of less than 1{times}10{sup {minus}3} ohm-cm. 4 figures.

  20. High quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1994-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  1. High quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1994-02-01

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  2. Biological chiral recognition: the substrate's perspective.

    PubMed

    Sundaresan, Vidyasankar; Abrol, Ravinder

    2005-01-01

    A novel stereocenter-recognition (SR) model has been proposed recently for describing the stereoselectivity of biological and other macromolecules towards substrates that have multiple stereocenters, based on the topology of substrate stereocenters (Sundaresan and Abrol, Prot Sci 11:1330-1339, 2002). The SR model provides the minimum number of substrate locations interacting with receptor sites that need to be considered for understanding stereoselectivity characteristics. Interactions between substrate locations and receptor sites may be binding, nonbinding or repulsive in nature and may occur in a many-to-one or one-to-many fashion, but for a receptor to be stereoselective, its interactions with substrate stereoisomers have to involve a minimum number of locations, in the correct geometry. The SR model is topologically rigorous, explains several previous experimental observations, and is predictive in nature. It predicts that stereoselectivity towards a substrate with N stereocenters in a linear structure involves a minimum of N + 2 substrate locations, distributed over all stereocenters in the substrate, such that effectively at least three locations per stereocenter interact with one or more receptor sites. This article uses the SR model to provide an insight into the chiral recognition process from a substrate's perspective that is intuitive and simple, furnishing a rigorous stereochemical basis for explaining stereoselectivity characteristics of many biological systems.

  3. Photovoltaic cell with nano-patterned substrate

    DOEpatents

    Cruz-Campa, Jose Luis; Zhou, Xiaowang; Zubia, David

    2016-10-18

    A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

  4. Foam drainage placed on a porous substrate.

    PubMed

    Arjmandi-Tash, O; Kovalchuk, N; Trybala, A; Starov, V

    2015-05-14

    A model for drainage/imbibition of a foam placed on the top of a porous substrate is presented. The equation of liquid imbibition into the porous substrate is coupled with a foam drainage equation at the foam/porous substrate interface. The deduced dimensionless equations are solved using a finite element method. It was found that the kinetics of foam drainage/imbibition depends on three dimensionless numbers and the initial liquid volume fraction. The result shows that there are three different regimes of the process. Each regime starts after initial rapid decrease of a liquid volume fraction at the foam/porous substrate interface: (i) rapid imbibition: the liquid volume fraction inside the foam at the foam/porous substrate interface remains constant close to a final liquid volume fraction; (ii) intermediate imbibition: the liquid volume fraction at the interface with the porous substrate experiences a peak point and imbibition into the porous substrate is slower as compared with the drainage; (iii) slow imbibition: the liquid volume fraction at the foam/porous substrate interface increases to a maximum limiting value and a free liquid layer is formed between the foam and the porous substrate. However, the free liquid layer disappears after some time. The transition points between these three different drainage/imbibition regimes were delineated by introducing two dimensionless numbers.

  5. Dancing drops over vibrating substrates

    NASA Astrophysics Data System (ADS)

    Borcia, Rodica; Borcia, Ion Dan; Helbig, Markus; Meier, Martin; Egbers, Christoph; Bestehorn, Michael

    2017-04-01

    We study the motion of a liquid drop on a solid plate simultaneously submitted to horizontal and vertical harmonic vibrations. The investigation is done via a phase field model earlier developed for describing static and dynamic contact angles. The density field is nearly constant in every bulk region (ρ = 1 in the liquid phase, ρ ≈ 0 in the vapor phase) and varies continuously from one phase to the other with a rapid but smooth variation across the interfaces. Complicated explicit boundary conditions along the interface are avoided and captured implicitly by gradient terms of ρ in the hydrodynamic basic equations. The contact angle θ is controlled through the density at the solid substrate ρ S , a free parameter varying between 0 and 1 [R. Borcia, I.D. Borcia, M. Bestehorn, Phys. Rev. E 78, 066307 (2008)]. We emphasize the swaying and the spreading modes, earlier theoretically identified by Benilov and Billingham via a shallow-water model for drops climbing uphill along an inclined plane oscillating vertically [E.S. Benilov, J. Billingham, J. Fluid Mech. 674, 93 (2011)]. The numerical phase field simulations will be completed by experiments. Some ways to prevent the release of the dancing drops along a hydrophobic surface into the gas atmosphere are also discussed in this paper.

  6. Dancing drops over vibrating substrates

    NASA Astrophysics Data System (ADS)

    Borcia, Rodica; Borcia, Ion Dan; Helbig, Markus; Meier, Martin; Egbers, Christoph; Bestehorn, Michael

    2016-08-01

    We study the motion of a liquid drop on a solid plate simultaneously submitted to horizontal and vertical harmonic vibrations. The investigation is done via a phase field model earlier developed for describing static and dynamic contact angles. The density field is nearly constant in every bulk region (ρ = 1 in the liquid phase, ρ ≈ 0 in the vapor phase) and varies continuously from one phase to the other with a rapid but smooth variation across the interfaces. Complicated explicit boundary conditions along the interface are avoided and captured implicitly by gradient terms of ρ in the hydrodynamic basic equations. The contact angle θ is controlled through the density at the solid substrate ρS, a free parameter varying between 0 and 1 [R. Borcia, I.D. Borcia, M. Bestehorn, Phys. Rev. E 78, 066307 (2008)]. We emphasize the swaying and the spreading modes, earlier theoretically identified by Benilov and Billingham via a shallow-water model for drops climbing uphill along an inclined plane oscillating vertically [E.S. Benilov, J. Billingham, J. Fluid Mech. 674, 93 (2011)]. The numerical phase field simulations will be completed by experiments. Some ways to prevent the release of the dancing drops along a hydrophobic surface into the gas atmosphere are also discussed in this paper.

  7. Neural substrates underlying intentional empathy

    PubMed Central

    Wang, Gang; Yang, Xuedong; Wang, Xiaoying; Northoff, Georg; Han, Shihui

    2012-01-01

    Although empathic responses to stimuli with emotional contents may occur automatically, humans are capable to intentionally empathize with other individuals. Intentional empathy for others is even possible when they do not show emotional expressions. However, little is known about the neuronal mechanisms of this intentionally controlled empathic process. To investigate the neuronal substrates underlying intentional empathy, we scanned 20 healthy Chinese subjects, using fMRI, when they tried to feel inside the emotional states of neutral or angry faces of familiar (Asian) and unfamiliar (Caucasian) models. Skin color evaluation of the same stimuli served as a control task. Compared to a baseline condition, the empathy task revealed a network of established empathy regions, including the anterior cingulate cortex, bilateral inferior frontal cortex and bilateral anterior insula. The contrast of intentional empathy vs skin color evaluation, however, revealed three regions: the bilateral inferior frontal cortex, whose hemodynamic responses were independent of perceived emotion and familiarity and the right-middle temporal gyrus, whose activity was modulated by emotion but not by familiarity. These findings extend our understanding of the role of the inferior frontal cortex and the middle temporal gyrus in empathy by demonstrating their involvement in intentional empathy. PMID:21511824

  8. Cancer and the metastatic substrate

    PubMed Central

    Arvelo, Francisco; Sojo, Felipe; Cotte, Carlos

    2016-01-01

    Seventy percent of cancer patients have detectable metastases when they receive a diagnosis and 90% of cancer deaths result from metastases. These two facts emphasise the urgency for research to study the mechanisms and processes that enable metastasis. We need to develop a greater understanding of the cellular and molecular mechanisms that cause metastasis and also we need to do more. We must also consider the micro- and macro-environmental factors that influence this disease. Studying this environmental context has led us to update the ‘seed and soil’ hypothesis which dates back to the 19th century. This theory describes cancerous cells as seeds and the substrate as the soil in target organs though this may seem antiquated. Nonetheless, the tissue specificity that researchers have recently observed in metastatic colonisation supports the validity of the seed and soil theory. We now know that the metastatic potential of a tumour cell depends on multiple, reciprocal interactions between the primary tumour and distant sites. These interactions determine tumour progression. Studies of metastasis have allowed us to develop treatments that focus on therapeutic effectiveness. These new treatments account for the frequent metastasis of some tumours to target organs such as bones, lungs, brain, and liver. The purpose of this review is first to describe interactions between the cellular and molecular entities and the target organ tumour environment that enables metastasis. A second aim is to describe the complex mechanisms that mediate these interactions. PMID:28105072

  9. Surface Modification of Nanocellulose Substrates

    NASA Astrophysics Data System (ADS)

    Zoppe, Justin Orazio

    Cellulose fibers constitute an important renewable raw material that is utilized in many commercial applications in non-food, paper, textiles and composite materials. Chemical functionalization is an important approach for improving the properties of cellulose based materials. Different approaches are used to graft polymeric chains onto cellulose substrates, which can be classified by two principal routes, namely 'grafting onto' or 'grafting from' methods. Never-dried cellulose nanocrystals (CNCs) or nanowhiskers produced from sulfuric acid hydrolysis of ramie fibers were used as substrates for surface chemical functionalization with various macromolecules. In addition, the use of cellulose nanocrystals to reinforce poly(epsilon-caprolactone) (PCL) nanofibers was studied. Chemical grafting with low molecular weight polycaprolactone diol onto cellulose nanocrystals was carried out in an attempt to improve the interfacial adhesion with the fiber matrix. Significant improvements in the mechanical properties of the nanofibers after reinforcement with unmodified cellulose nanocrystals were confirmed. Fiber webs from PCL reinforced with 2.5% unmodified CNCs showed ca. 1.5-fold increase in Young's modulus and ultimate strength compared to PCL webs. The CNCs were also grafted with poly(N-isopropylacrylamide) (poly(NiPAAm)) brushes via surface-initiated single-electron transfer living radical polymerization (SI-SETLRP) under various conditions at room temperature. The grafting process depended on the initiator and/or monomer concentrations used. No observable damage occurred to the CNCs after grafting, as determined by X-ray diffraction. Size exclusion chromatography analyses of polymer chains cleaved from the cellulose nanocrystals indicated that a higher degree of polymerization was achieved by increasing initiator or monomer loading, most likely caused by local heterogeneities yielding higher rates of polymerization. In addition, the colloidal stability and thermo

  10. Microfabricated force-sensitive elastic substrates for investigation of mechanical cell substrate interactions

    NASA Astrophysics Data System (ADS)

    Petronis, Sarunas; Gold, Julie; Kasemo, Bengt

    2003-11-01

    Mechanical cell-substrate interactions affect many aspects of cellular functions. In order to investigate these interactions, we have microfabricated force-sensitive cell adhesion substrates. A new design of the substrates has been proposed, where force detection is based on monitoring deflection of close-packed standing cantilevers constituting the surface. Such a force-sensitive substrate may be used both for modulating substrates of different elasticity as well as for measuring local mechanical forces from the cell adhesion contacts. The substrates with different cantilever geometry and spatial arrangement have been microfabricated in oxidized silicon wafers using photolithography and deep reactive ion etching. Scanning electron microscopy and atomic force microscopy have been used to measure the dimensions of the cantilevers and to estimate their spring constants. Cell culture experiments on the microfabricated substrates have been performed to test the applicability of the substrates in different experimental setups.

  11. Resist Characterization On Reflecting Substrates

    NASA Astrophysics Data System (ADS)

    Hayes, John; Bell, William R.; Ferguson, Richard; Neureuther, Andrew R.

    1986-07-01

    The bottleneck of quantitative characterization of resist materials is being relieved by the introduction of a commercial system with multiple channel capabilities working directly on silicon wafers. This convenience for the process engineer comes at considerable inconvenience in data analysis, primarily due to exposure standing wave effects from substrate reflection. On silicon, for example, an exposure variation of a factor of 8 occurs over a vertical distance of 65 nm within the resist. Data from this very thin layer can span almost the entire range of exposure state M of the resist and two orders of magnitude change in development rates. Experimental and software techniques developed in a benchmark study of the well characterized Kodak 820 resist are reported. Several software techniques were established for data analysis. A depth-dependent filtering technique was used to improve the signal-to-noise ratio of the rate vs depth data from the slowly developing channels. This noise is due to the high sampling rates, which are necessary to simultaneously monitor the most rapidly developing areas. A post processor for SAMPLE was developed to process the normal output of exposure state M versus depth and generate M values for the exposures specified in the data from the measurement system. A three column vector of development rate R, exposure state M and depth z is then generated for plotting R(M,z) and numerically fitting algebraic models. Measurements and data reduction were made on silicon wafers with various thin film coatings. A hard-baked resist coating was sufficiently absorbing that very little oscillation in the development rate with depth was observed. For aluminum coatings, it was not possible to get good thickness vs time or rate data. The rate versus depth on bare silicon wafers could be made well behaved after filtering. The resulting R(M,z) curve for bare silicon was somewhat noisy. Thus the use of a hard-baked coating is indicated in practice for

  12. Buffer layers on biaxially textured metal substrates

    DOEpatents

    Shoup, Shara S.; Paranthamam, Mariappan; Beach, David B.; Kroeger, Donald M.; Goyal, Amit

    2001-01-01

    A method is disclosed for forming a biaxially textured buffer layer on a biaxially oriented metal substrate by using a sol-gel coating technique followed by pyrolyzing/annealing in a reducing atmosphere. This method is advantageous for providing substrates for depositing electronically active materials thereon.

  13. Direct transfer of graphene onto flexible substrates.

    PubMed

    Martins, Luiz G P; Song, Yi; Zeng, Tingying; Dresselhaus, Mildred S; Kong, Jing; Araujo, Paulo T

    2013-10-29

    In this paper we explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate transfer membrane, such as polymethylmethacrylate, which needs to be removed afterward. Various substrates of general interest in research and industry were studied in this work, including polytetrafluoroethylene filter membranes, PVC, cellulose nitrate/cellulose acetate filter membranes, polycarbonate, paraffin, polyethylene terephthalate, paper, and cloth. By comparing the properties of these substrates, two critical factors to ensure a successful transfer on bare substrates were identified: the substrate's hydrophobicity and good contact between the substrate and graphene. For substrates that do not satisfy those requirements, polymethylmethacrylate can be used as a surface modifier or glue to ensure successful transfer. Our results can be applied to facilitate current processes and open up directions for applications of chemical vapor deposition graphene on flexible substrates. A broad range of applications can be envisioned, including fabrication of graphene devices for opto/organic electronics, graphene membranes for gas/liquid separation, and ubiquitous electronics with graphene.

  14. Cellulose Nanofiber Composite Substrates for Flexible Electronics

    Treesearch

    Ronald Sabo; Jung-Hun Seo; Zhenqiang Ma

    2012-01-01

    Flexible electronics have a large number of potential applications including malleable displays and wearable computers. The current research into high-speed, flexible electronic substrates employs the use of plastics for the flexible substrate, but these plastics typically have drawbacks, such as high thermal expansion coefficients. Transparent films made from...

  15. Biaxially textured metal substrate with palladium layer

    DOEpatents

    Robbins, William B [Maplewood, MN

    2002-12-31

    Described is an article comprising a biaxially textured metal substrate and a layer of palladium deposited on at least one major surface of the metal substrate; wherein the palladium layer has desired in-plane and out-of-plane crystallographic orientations, which allow subsequent layers that are applied on the article to also have the desired orientations.

  16. Direct transfer of graphene onto flexible substrates

    NASA Astrophysics Data System (ADS)

    Pimenta, Luiz Gustavo; Song, Yi; Zeng, Tingying; Dresselhaus, Mildred; Kong, Jing; Araujo, Paulo

    2014-03-01

    We explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate transfer membrane, such as polymethylmethacrylate. Various substrates of general interest in research and industry were studied including polytetrafluoroethylene filter membranes, PVC, cellulose nitrate/cellulose acetate filter membranes, polycarbonate, paraffin, polyethylene terephthalate, paper, and cloth. By comparing the properties of these substrates, two critical factors to ensure a successful transfer on bare substrates were identified: the substrate's hydrophobicity and good contact between the substrate and graphene. For substrates that do not satisfy those requirements, polymethylmethacrylate can be used as a surface modifier or glue to ensure successful transfer. Our results can be applied to facilitate present processes and open up directions for applications of chemical vapor deposition (CVD) graphene on flexible substrates. A broad range of applications of CVD graphene can be envisioned, including fabrication of graphene devices for opto/organic electronics, graphene membranes for gas/liquid separation, and ubiquitous electronics with graphene.

  17. Butyrate as preferred substrate for polyhydroxybutyrate production.

    PubMed

    Marang, Leonie; Jiang, Yang; van Loosdrecht, Mark C M; Kleerebezem, Robbert

    2013-08-01

    In this study, the suitability of butyrate as substrate for polyhydroxyalkanoate (PHA) production by microbial enrichment cultures was assessed. Two sequencing batch reactors were operated under feast-famine conditions: one fed with butyrate, and another with mixed acetate and butyrate. The obtained results were compared to previous results with acetate as sole substrate. In all three reactors Plasticicumulans acidivorans dominated the enrichment culture. The carbon uptake rate and PHA yield were significantly higher on butyrate than on acetate, resulting in a higher PHA production rate. When both substrates were available the bacteria strongly preferred the uptake of butyrate. Only after butyrate depletion acetate was taken up at a high rate. The molar substrate uptake rate remained the same, suggesting that substrate uptake is the rate-limiting step. The results show that for optimized waste-based PHA production the pre-fermentation process should be directed towards butyrate production.

  18. Substrate Effects for Atomic Chain Electronics

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Saini, Subhash (Technical Monitor)

    1998-01-01

    A substrate for future atomic chain electronics, where adatoms are placed at designated positions and form atomically precise device components, is studied theoretically. The substrate has to serve as a two-dimensional template for adatom mounting with a reasonable confinement barrier and also provide electronic isolation, preventing unwanted coupling between independent adatom structures. For excellent structural stability, we demand chemical bonding between the adatoms and substrate atoms, but then good electronic isolation may not be guaranteed. Conditions are clarified for good isolation. Because of the chemical bonding, fundamental adatom properties are strongly influenced: a chain with group IV adatoms having two chemical bonds, or a chain with group III adatoms having one chemical bond is semiconducting. Charge transfer from or to the substrate atoms brings about unintentional doping, and the electronic properties have to be considered for the entire combination of the adatom and substrate systems even if the adatom modes are well localized at the surface.

  19. Substrate solder barriers for semiconductor epilayer growth

    DOEpatents

    Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

    1989-05-09

    During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

  20. Substrate solder barriers for semiconductor epilayer growth

    DOEpatents

    Drummond, Timothy J.; Ginley, David S.; Zipperian, Thomas E.

    1989-01-01

    During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

  1. Substrate Binding to Cytochromes P450

    PubMed Central

    Isin, Emre M.; Guengerich, F. Peter

    2016-01-01

    P450s have attracted tremendous attention due not only to their involvement in the metabolism of drug molecules and endogenous substrates but also the unusual nature of the reaction they catalyze, namely the oxidation of unactivated C-H bonds. The binding of substrates to P450s, which is usually viewed as the first step in the catalytic cycle, has been studied extensively via a variety of biochemical and biophysical approaches. These studies were directed towards answering different questions related to P450s including, mechanism of oxidation, substrate properties, unusual substrate oxidation kinetics, function, and active site features. Some of the substrate binding studies extending over a period of more than forty years of dedicated work has been summarized in this review and categorized by the techniques employed in the binding studies. PMID:18622598

  2. Thin Film Transistors On Plastic Substrates

    DOEpatents

    Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

    2004-01-20

    A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The silicon based thin film transistor produced by the process includes a low temperature substrate incapable of withstanding sustained processing temperatures greater than about 250.degree. C., an insulating layer on the substrate, a layer of silicon on the insulating layer having sections of doped silicon, undoped silicon, and poly-silicon, a gate dielectric layer on the layer of silicon, a layer of gate metal on the dielectric layer, a layer of oxide on sections of the layer of silicon and the layer of gate metal, and metal contacts on sections of the layer of silicon and layer of gate metal defining source, gate, and drain contacts, and interconnects.

  3. Substrate pH Affects Nutrient Availability in Fertilized Douglas Fir Bark Substrates

    USDA-ARS?s Scientific Manuscript database

    An experiment was conducted to determine how pH and nutrient availability in Douglas fir bark substrates respond to lime and sulfur (S) rates. The treatment design was a two by nine factorial arrangement with two substrate types and nine pH-altering amendments. The two substrates were 100% DFB or ...

  4. Method of forming fluorine-bearing diamond layer on substrates, including tool substrates

    DOEpatents

    Chang, R. P. H.; Grannen, Kevin J.

    2002-01-01

    A method of forming a fluorine-bearing diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-bearing plasma or other gas are then contacted under temperature and pressure conditions effective to nucleate fluorine-bearing diamond on the substrate. A tool insert substrate is treated prior to the diamond nucleation and growth operation by etching both the metal matrix and the hard particles using suitable etchants.

  5. A trans-splicing group I intron and tRNA-hyperediting in the mitochondrial genome of the lycophyte Isoetes engelmannii

    PubMed Central

    Grewe, Felix; Viehoever, Prisca; Weisshaar, Bernd; Knoop, Volker

    2009-01-01

    Plant mitochondrial genomes show much more evolutionary plasticity than those of animals. We analysed the first mitochondrial DNA (mtDNA) of a lycophyte, the quillwort Isoetes engelmannii, which is separated from seed plants by more than 350 million years of evolution. The Isoetes mtDNA is particularly rich in recombination events, and chloroplast as well as nuclear DNA inserts document the incorporation of foreign sequences already in this most ancestral vascular plant lineage. On the other hand, particularly small group II introns and short intergenic regions reveal a tendency of evolution towards a compact mitochondrial genome. RNA editing reaches extreme levels exceeding 100 pyrimidine exchanges in individual mRNAs and, hitherto unobserved in such frequency, also in tRNAs with 18 C-to-U conversions in the tRNA for proline. In total, some 1500 sites of RNA editing can be expected for the Isoetes mitochondrial transcriptome. As a unique molecular novelty, the Isoetes cox1 gene requires trans-splicing via a discontinuous group I intron demonstrating disrupted, but functional, RNAs for yet another class of natural ribozymes. PMID:19553190

  6. Electron mobility calculation for graphene on substrates

    SciTech Connect

    Hirai, Hideki; Ogawa, Matsuto; Tsuchiya, Hideaki; Kamakura, Yoshinari; Mori, Nobuya

    2014-08-28

    By a semiclassical Monte Carlo method, the electron mobility in graphene is calculated for three different substrates: SiO{sub 2}, HfO{sub 2}, and hexagonal boron nitride (h-BN). The calculations account for polar and non-polar surface optical phonon (OP) scatterings induced by the substrates and charged impurity (CI) scattering, in addition to intrinsic phonon scattering in pristine graphene. It is found that HfO{sub 2} is unsuitable as a substrate, because the surface OP scattering of the substrate significantly degrades the electron mobility. The mobility on the SiO{sub 2} and h-BN substrates decreases due to CI scattering. However, the mobility on the h-BN substrate exhibits a high electron mobility of 170 000 cm{sup 2}/(V·s) for electron densities less than 10{sup 12 }cm{sup −2}. Therefore, h-BN should be an appealing substrate for graphene devices, as confirmed experimentally.

  7. Direct transfer of graphene onto flexible substrates

    PubMed Central

    Martins, Luiz G. P.; Song, Yi; Zeng, Tingying; Dresselhaus, Mildred S.; Kong, Jing; Araujo, Paulo T.

    2013-01-01

    In this paper we explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate transfer membrane, such as polymethylmethacrylate, which needs to be removed afterward. Various substrates of general interest in research and industry were studied in this work, including polytetrafluoroethylene filter membranes, PVC, cellulose nitrate/cellulose acetate filter membranes, polycarbonate, paraffin, polyethylene terephthalate, paper, and cloth. By comparing the properties of these substrates, two critical factors to ensure a successful transfer on bare substrates were identified: the substrate’s hydrophobicity and good contact between the substrate and graphene. For substrates that do not satisfy those requirements, polymethylmethacrylate can be used as a surface modifier or glue to ensure successful transfer. Our results can be applied to facilitate current processes and open up directions for applications of chemical vapor deposition graphene on flexible substrates. A broad range of applications can be envisioned, including fabrication of graphene devices for opto/organic electronics, graphene membranes for gas/liquid separation, and ubiquitous electronics with graphene. PMID:24127582

  8. A new approach to modelling substrate inhibition.

    PubMed

    Meriç, S; Tünay, O; Ali, S H

    2002-02-01

    Substrate inhibition, which is one of the most frequently observed phenomena in the biological treatment of industrial wastewaters, has been the subject of numerous studies. Yet there are still cases which cannot be adequately described by the existing models. In this paper, a review of substrate inhibition approaches was made. A new model is proposed that assumes a common mechanism for substrate and product inhibition. The model is a continuous function having a maximum growth rate at the critical substrate concentration, beyond which the growth rate decreases as the substrate concentration is increased. The model also predicts the maximum substrate concentration where the growth ceases. The model was tested using existing data in the literature to assess the model response and predictability of critical points. The literature datahave been selected from the studies conducted on pure and mixed cultures in batch and continuous reactors for phenol and several phenolics as well as from the studies which employed the Haldane model. A curve fitting method was used to determine the model parameters. The fit of the model to the data was satisfactory, particularly for the substrate concentrations exceeding maximum growth rate.

  9. Substrate binding to mammalian 15-lipoxygenase

    NASA Astrophysics Data System (ADS)

    Toledo, Lea; Masgrau, Laura; Lluch, José M.; González-Lafont, Àngels

    2011-09-01

    Lipoxygenases (LOs) are implicated in the regulation of metabolic processes and in several human diseases. Revealing their exact role is hindered by an incomplete understanding of their activity, including substrate specificity and substrate alignment in the active site. Recently, it has been proposed that the change in substrate specificity for arachidonic acid (AA) or linoleic acid (LA) could be part of an auto-regulatory mechanism related to cancer grow. Kinetic differences between reactions of 15-hLO with AA and LA have also led to the suggestion that the two substrates could present mechanistic differences. In the absence of a crystal structure for the substrate:15-LO complex, here we present an atomic-level study of catalytically competent binding modes for LA to rabbit 15-LO (15-rLO-1) and compare the results to our previous work on AA. Docking calculations, molecular dynamics simulations, re-docking and cross-docking calculations are all used to analyze the differences and similarities between the binding modes of the two substrates. Interestingly, LA seems to adapt more easily to the enzyme structure and differs from AA on some dynamical aspects that could introduce kinetic differences, as observed experimentally. Still, our study concludes that, despite the different chain lengths and number of insaturations between these two physiological substrates of 15-rLO-1, the enzyme seems to catalyze their hydroperoxidation by binding them with a common binding mode that leads to similar catalytically competent complexes.

  10. Metallic coatings on silicon substrates, and methods of forming metallic coatings on silicon substrates

    DOEpatents

    Branagan, Daniel J.; Hyde, Timothy A.; Fincke, James R.

    2008-03-11

    The invention includes methods of forming a metallic coating on a substrate which contains silicon. A metallic glass layer is formed over a silicon surface of the substrate. The invention includes methods of protecting a silicon substrate. The substrate is provided within a deposition chamber along with a deposition target. Material from the deposition target is deposited over at least a portion of the silicon substrate to form a protective layer or structure which contains metallic glass. The metallic glass comprises iron and one or more of B, Si, P and C. The invention includes structures which have a substrate containing silicon and a metallic layer over the substrate. The metallic layer contains less than or equal to about 2 weight % carbon and has a hardness of at least 9.2 GPa. The metallic layer can have an amorphous microstructure or can be devitrified to have a nanocrystalline microstructure.

  11. Implantable biomedical devices on bioresorbable substrates

    DOEpatents

    Rogers, John A; Kim, Dae-Hyeong; Omenetto, Fiorenzo; Kaplan, David L; Litt, Brian; Viventi, Jonathan; Huang, Yonggang; Amsden, Jason

    2014-03-04

    Provided herein are implantable biomedical devices, methods of administering implantable biomedical devices, methods of making implantable biomedical devices, and methods of using implantable biomedical devices to actuate a target tissue or sense a parameter associated with the target tissue in a biological environment. Each implantable biomedical device comprises a bioresorbable substrate, an electronic device having a plurality of inorganic semiconductor components supported by the bioresorbable substrate, and a barrier layer encapsulating at least a portion of the inorganic semiconductor components. Upon contact with a biological environment the bioresorbable substrate is at least partially resorbed, thereby establishing conformal contact between the implantable biomedical device and the target tissue in the biological environment.

  12. Microstrip antennas and arrays on chiral substrates

    NASA Astrophysics Data System (ADS)

    Pozar, David M.

    1992-10-01

    Results are presented for isolated microstrip antennas and infinite arrays of microstrip antennas printed on chiral substrates, computed from full-wave spectral domain moment method solutions. Data for resonant length, impedance, directivity, efficiency, cross-polarization level, and scan performance are given, and compared to results obtained for a dielectric substrate of the same thickness and permittivity. It is concluded that, from the point of view of antenna characteristics, there does not seem to be any advantage to using chiral antenna substrates, while there are disadvantages in terms of increased cross-pol levels and losses due to surface wave excitation.

  13. Evaporation of droplets on strongly hydrophobic substrates.

    PubMed

    Stauber, Jutta M; Wilson, Stephen K; Duffy, Brian R; Sefiane, Khellil

    2015-03-31

    The manner in which the extreme modes of droplet evaporation (namely, the constant contact radius and the constant contact angle modes) become indistinguishable on strongly hydrophobic substrates is described. Simple asymptotic expressions are obtained which provide good approximations to the evolutions of the contact radius, the contact angle, and the volume of droplets evaporating in the extreme modes for a wide range of hydrophobic substrates. As a consequence, on strongly hydrophobic substrates it is appropriate to use the so-called "2/3 power law" to extrapolate the lifetimes of droplets evaporating in the constant contact radius mode as well as in the constant contact angle mode.

  14. Substrates for clinical applicability of stem cells

    PubMed Central

    Enam, Sanjar; Jin, Sha

    2015-01-01

    The capability of human pluripotent stem cells (hPSCs) to differentiate into a variety of cells in the human body holds great promise for regenerative medicine. Many substrates exist on which hPSCs can be self-renewed, maintained and expanded to further the goal of clinical application of stem cells. In this review, we highlight numerous extracellular matrix proteins, peptide and polymer based substrates, scaffolds and hydrogels that have been pioneered. We discuss their benefits and shortcomings and offer future directions as well as emphasize commercially available synthetic peptides as a type of substrate that can bring the benefits of regenerative medicine to clinical settings. PMID:25815112

  15. Wafer bonded virtual substrate and method for forming the same

    DOEpatents

    Atwater, Jr., Harry A.; Zahler, James M.; Morral, Anna Fontcuberta i

    2007-07-03

    A method of forming a virtual substrate comprised of an optoelectronic device substrate and handle substrate comprises the steps of initiating bonding of the device substrate to the handle substrate, improving or increasing the mechanical strength of the device and handle substrates, and thinning the device substrate to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. The handle substrate is typically Si or other inexpensive common substrate material, while the optoelectronic device substrate is formed of more expensive and specialized electro-optic material. Using the methodology of the invention a wide variety of thin film electro-optic materials of high quality can be bonded to inexpensive substrates which serve as the mechanical support for an optoelectronic device layer fabricated in the thin film electro-optic material.

  16. Wafer bonded virtual substrate and method for forming the same

    NASA Technical Reports Server (NTRS)

    Atwater, Jr., Harry A. (Inventor); Zahler, James M. (Inventor); Morral, Anna Fontcuberta i (Inventor)

    2007-01-01

    A method of forming a virtual substrate comprised of an optoelectronic device substrate and handle substrate comprises the steps of initiating bonding of the device substrate to the handle substrate, improving or increasing the mechanical strength of the device and handle substrates, and thinning the device substrate to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. The handle substrate is typically Si or other inexpensive common substrate material, while the optoelectronic device substrate is formed of more expensive and specialized electro-optic material. Using the methodology of the invention a wide variety of thin film electro-optic materials of high quality can be bonded to inexpensive substrates which serve as the mechanical support for an optoelectronic device layer fabricated in the thin film electro-optic material.

  17. Pressure-Sensitive Paint: Effect of Substrate

    PubMed Central

    Quinn, Mark Kenneth; Yang, Leichao; Kontis, Konstantinos

    2011-01-01

    There are numerous ways in which pressure-sensitive paint can be applied to a surface. The choice of substrate and application method can greatly affect the results obtained. The current study examines the different methods of applying pressure-sensitive paint to a surface. One polymer-based and two porous substrates (anodized aluminum and thin-layer chromatography plates) are investigated and compared for luminescent output, pressure sensitivity, temperature sensitivity and photodegradation. Two luminophores [tris-Bathophenanthroline Ruthenium(II) Perchlorate and Platinum-tetrakis (pentafluorophenyl) Porphyrin] will also be compared in all three of the substrates. The results show the applicability of the different substrates and luminophores to different testing environments. PMID:22247685

  18. Substrate Control in Stereoselective Lanthionine Biosynthesis

    PubMed Central

    Tang, Weixin; Jiménez-Osés, Gonzalo; Houk, K. N.; van der Donk, Wilfred A.

    2014-01-01

    Enzymes are typically highly stereoselective catalysts that enforce a reactive conformation on their native substrates. We report here a rare example where the substrate controls the stereoselectivity of an enzyme-catalyzed Michael-type addition during the biosynthesis of lanthipeptides. These natural products contain thioether crosslinks formed by cysteine attack on dehydrated Ser and Thr residues. We demonstrate that several lanthionine synthetases catalyze highly selective anti additions in which the substrate (and not the enzyme) determines whether the addition occurs from the Re or Si face. A single point mutation in the peptide substrate completely inverted the stereochemical outcome of the enzymatic modification. Quantum mechanical calculations reproduced the experimentally observed selectivity and suggest that conformational restraints imposed by the amino acid sequence on the transition states determine the face selectivity of the Michael-type cyclization. PMID:25515891

  19. Process for Coating Substrates with Catalytic Materials

    NASA Technical Reports Server (NTRS)

    Klelin, Ric J. (Inventor); Upchurch, Billy T. (Inventor); Schryer, David R. (Inventor)

    2004-01-01

    A process for forming catalysts by coating substrates with two or more catalytic components, which comprises the following sequence of steps. First, the substrate is infused with an adequate amount of solution having a starting material comprising a catalytic component precursor, wherein the thermal decomposition product of the catalytic component precursor is a catalytic component. Second, the excess of the solution is removed from the substrate. thereby leaving a coating of the catalytic component precursor on the surface of the substrate. Third, the coating of the catalytic component precursor is converted to the catalytic component by thermal decomposition. Finally, the coated substance is etched to increase the surface area. The list three steps are then repeated for at least a second catalytic component. This process is ideally suited for application in producing efficient low temperature oxidation catalysts.

  20. Off-axis silicon carbide substrates

    DOEpatents

    Edgar, James; Dudley, Michael; Kuball, Martin; Zhang, Yi; Wang, Guan; Chen, Hui; Zhang, Yu

    2014-09-02

    A method of epitaxial growth of a material on a crystalline substrate includes selecting a substrate having a crystal plane that includes a plurality of terraces with step risers that join adjacent terraces. Each terrace of the plurality or terraces presents a lattice constant that substantially matches a lattice constant of the material, and each step riser presents a step height and offset that is consistent with portions of the material nucleating on adjacent terraces being in substantial crystalline match at the step riser. The method also includes preparing a substrate by exposing the crystal plane; and epitaxially growing the material on the substrate such that the portions of the material nucleating on adjacent terraces merge into a single crystal lattice without defects at the step risers.

  1. Iron films deposited on porous alumina substrates

    NASA Astrophysics Data System (ADS)

    Yamada, Yasuhiro; Tanabe, Kenichi; Nishida, Naoki; Kobayashi, Yoshio

    2016-12-01

    Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 - 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.

  2. Substrate stress relaxation regulates cell spreading

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Ovijit; Gu, Luo; Darnell, Max; Klumpers, Darinka; Bencherif, Sidi A.; Weaver, James C.; Huebsch, Nathaniel; Mooney, David J.

    2015-02-01

    Studies of cellular mechanotransduction have converged upon the idea that cells sense extracellular matrix (ECM) elasticity by gauging resistance to the traction forces they exert on the ECM. However, these studies typically utilize purely elastic materials as substrates, whereas physiological ECMs are viscoelastic, and exhibit stress relaxation, so that cellular traction forces exerted by cells remodel the ECM. Here we investigate the influence of ECM stress relaxation on cell behaviour through computational modelling and cellular experiments. Surprisingly, both our computational model and experiments find that spreading for cells cultured on soft substrates that exhibit stress relaxation is greater than cells spreading on elastic substrates of the same modulus, but similar to that of cells spreading on stiffer elastic substrates. These findings challenge the current view of how cells sense and respond to the ECM.

  3. Substrate solder barriers for semiconductor epilayer growth

    DOEpatents

    Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

    1987-10-23

    During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In molecular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating. 1 tab.

  4. Graphene plasmon propagation on corrugated silicon substrates.

    PubMed

    Kong, Xiang-Tian; Bai, Bing; Dai, Qing

    2015-01-01

    The scheme of graphene on a silicon substrate is potentially compatible to the microelectronic technology. But the maintained plasmons have considerable ohmic loss because of silicon's large permittivity. We introduce air grooves in the silicon surface to reduce the optical thickness of substrate and hence decrease the propagation loss. The properties of graphene plasmons on the corrugated substrates are numerically investigated, in terms of the photon frequency and the geometrical parameters of the corrugated layer, considering both ohmic loss and scattering loss. The plasmons propagation lengths for the corrugated substrates can exceed twice of those for flat silicon in a broadband in mid-infrared. This study may be useful for designing of compact mid-infrared waveguides based on graphene for future photonic integrated circuits.

  5. Substrate-supported lipid nanotube arrays.

    SciTech Connect

    Smirnov, A. I.; Poluektov, O. G.; Chemistry; North Carolina State

    2003-07-16

    This Communication describes the self-assembly of phospholipids into lipid nanotubes inside nanoporous anodic aluminum oxide substrate. Orientations of the lipid molecules in such lipid nanoscale structures were verified by high-resolution spin labeling EPR at 95 GHz. The static order parameter of lipids in such nanotube arrays was determined from low-temperature EPR spectra and was found to be exceptionally high, S{sub static} {approx} 0.9. We propose that substrate-supported lipid nanotube arrays have potential for building robust biochips and biosensors in which rigid nanoporous substrates protect the bilayer surface from contamination. The total bilayer surface in the lipid nanotube arrays is much greater than that in the planar substrate-supported membranes. The lipid nanotube arrays seem to be suitable for developing patterned lipid deposition and could be potentially used for patterning of membrane-associated molecules.

  6. Substrate influences on CIS device performance

    SciTech Connect

    Dawson-Elli, D.F.; Moore, C.B.; Gay, R.R.; Jensen, C.L.

    1994-12-31

    It has been reported that the substrate plays an active role in copper indium diselenide (CIS) devices. The physical properties of the substrate, i.e., thermal expansion coefficient, chemical composition, strain point, surface quality and cleanliness may all play a role in device efficiency and process reproducibility. For example, sodium is known to influence the conductivity of CIS, and that soda lime glass (SLG) introduces sodium into the CIS. In the experiments reported here, the sodium level in the CIS was varied by (a) changing the substrate composition and (b) the use of SiO{sub x}N{sub y} and SiN{sub x} barrier layers. Cells were fabricated on the candidate substrate and barrier layer combinations. V{sub oc} was observed to drop with the addition of barrier layers to sodium containing glasses. The films were also analyzed for sodium by SIMS. The cell performance and SIMS analysis are presented and their significance is discussed.

  7. Laser/plasma chemical processing of substrates

    DOEpatents

    Gee, James M.; Hargis, Jr., Philip J.

    1986-01-01

    A process for the modification of substrate surfaces is described, wherein etching or deposition at a surface occurs only in the presence of both reactive species and a directed beam of coherent light.

  8. Substrate control in stereoselective lanthionine biosynthesis

    NASA Astrophysics Data System (ADS)

    Tang, Weixin; Jiménez-Osés, Gonzalo; Houk, K. N.; van der Donk, Wilfred A.

    2015-01-01

    Enzymes are typically highly stereoselective catalysts that enforce a reactive conformation on their native substrates. We report here a rare example in which the substrate controls the stereoselectivity of an enzyme-catalysed Michael-type addition during the biosynthesis of lanthipeptides. These natural products contain thioether crosslinks formed by a cysteine attack on dehydrated Ser and Thr residues. We demonstrate that several lanthionine synthetases catalyse highly selective anti-additions in which the substrate (and not the enzyme) determines whether the addition occurs from the re or si face. A single point mutation in the peptide substrate completely inverted the stereochemical outcome of the enzymatic modification. Quantum mechanical calculations reproduced the experimentally observed selectivity and suggest that conformational restraints imposed by the amino-acid sequence on the transition states determine the face selectivity of the Michael-type cyclization.

  9. An Acrobatic Substrate Metamorphosis Reveals a Requirement for Substrate Conformational Dynamics in Trypsin Proteolysis

    DOE PAGES

    Kayode, Olumide; Wang, Ruiying; Pendlebury, Devon F.; ...

    2016-11-03

    The molecular basis of enzyme catalytic power and specificity derives from dynamic interactions between enzyme and substrate during catalysis. While considerable effort has been devoted to understanding how conformational dynamics within enzymes affect catalysis, the role of conformational dynamics within protein substrates has not been addressed. Here in this paper, we examine the importance of substrate dynamics in the cleavage of Kunitz-BPTI protease inhibitors by mesotrypsin, finding that the varied conformational dynamics of structurally similar substrates can profoundly impact the rate of catalysis. A 1.4 Å crystal structure of a mesotrypsin-product complex formed with a rapidly cleaved substrate reveals amore » dramatic conformational change in the substrate upon proteolysis. Using long all-atom molecular dynamics simulations of acyl-enzyme intermediates with proteolysis rates spanning three orders of magnitude, we identify global and local dynamic features of substrates on the ns-μs timescale that correlate with enzymatic rates and explain differential susceptibility to proteolysis. By integrating multiple enhanced sampling methods for molecular dynamics, we model a viable conformational pathway between substratelike and product-like states, linking substrate dynamics on the ns-μs timescale with large collective substrate motions on the much slower timescale of catalysis. Our findings implicate substrate flexibility as a critical determinant of catalysis.« less

  10. An Acrobatic Substrate Metamorphosis Reveals a Requirement for Substrate Conformational Dynamics in Trypsin Proteolysis

    SciTech Connect

    Kayode, Olumide; Wang, Ruiying; Pendlebury, Devon F.; Cohen, Itay; Henin, Rachel D.; Hockla, Alexandra; Soares, Alexei S.; Papo, Niv; Caulfield, Thomas R.; Radisky, Evette S.

    2016-11-03

    The molecular basis of enzyme catalytic power and specificity derives from dynamic interactions between enzyme and substrate during catalysis. While considerable effort has been devoted to understanding how conformational dynamics within enzymes affect catalysis, the role of conformational dynamics within protein substrates has not been addressed. Here in this paper, we examine the importance of substrate dynamics in the cleavage of Kunitz-BPTI protease inhibitors by mesotrypsin, finding that the varied conformational dynamics of structurally similar substrates can profoundly impact the rate of catalysis. A 1.4 Å crystal structure of a mesotrypsin-product complex formed with a rapidly cleaved substrate reveals a dramatic conformational change in the substrate upon proteolysis. Using long all-atom molecular dynamics simulations of acyl-enzyme intermediates with proteolysis rates spanning three orders of magnitude, we identify global and local dynamic features of substrates on the ns-μs timescale that correlate with enzymatic rates and explain differential susceptibility to proteolysis. By integrating multiple enhanced sampling methods for molecular dynamics, we model a viable conformational pathway between substratelike and product-like states, linking substrate dynamics on the ns-μs timescale with large collective substrate motions on the much slower timescale of catalysis. Our findings implicate substrate flexibility as a critical determinant of catalysis.

  11. Superconducting thin films on potassium tantalate substrates

    DOEpatents

    Feenstra, Roeland; Boatner, Lynn A.

    1992-01-01

    A superconductive system for the lossless transmission of electrical current comprising a thin film of superconducting material Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7-x epitaxially deposited upon a KTaO.sub.3 substrate. The KTaO.sub.3 is an improved substrate over those of the prior art since the it exhibits small lattice constant mismatch and does not chemically react with the superconducting film.

  12. Composition containing aerogel substrate loaded with tritium

    DOEpatents

    Ashley, Carol S.; Brinker, C. Jeffrey; Ellefson, Robert E.; Gill, John T.; Reed, Scott; Walko, Robert J.

    1992-01-01

    The invention provides a process for loading an aerogel substrate with tritium and the resultant compositions. According to the process, an aerogel substrate is hydrolyzed so that surface OH groups are formed. The hydrolyzed aerogel is then subjected to tritium exchange employing, for example, a tritium-containing gas, whereby tritium atoms replace H atoms of surface OH groups. OH and/or CH groups of residual alcohol present in the aerogel may also undergo tritium exchange.

  13. Fabrication of novel plasmonics-active substrates

    NASA Astrophysics Data System (ADS)

    Dhawan, Anuj; Gerhold, Michael; Du, Yan; Misra, Veena; Vo-Dinh, Tuan

    2009-02-01

    This paper describes methodologies for fabricating of highly efficient plasmonics-active SERS substrates - having metallic nanowire structures with pointed geometries and sub-5 nm gap between the metallic nanowires enabling concentration of high EM fields in these regions - on a wafer-scale by a reproducible process that is compatible with large-scale development of these substrates. Excitation of surface plasmons in these nanowire structures leads to substantial enhancement in the Raman scattering signal obtained from molecules lying in the vicinity of the nanostructure surface. The methodologies employed included metallic coating of silicon nanowires fabricated by employing deep UV lithography as well as controlled growth of silicon germanium on silicon nanostructures to form diamond-shaped nanowire structures followed by metallic coating. These SERS substrates were employed for detecting chemical and biological molecules of interest. In order to characterize the SERS substrates developed in this work, we obtained SERS signals from molecules such as p-mercaptobenzoic acid (pMBA) and cresyl fast violet (CFV) attached to or adsorbed on the metal-coated SERS substrates. It was observed that both gold-coated triangular shaped nanowire substrates as well as gold-coated diamond shaped nanowire substrates provided very high SERS signals for the nanowires having sub-15 nm gaps and that the SERS signal depends on the closest spacing between the metal-coated silicon and silicon germanium nanowires. SERS substrates developed by the different processes were also employed for detection of biological molecules such as DPA (Dipicolinic Acid), an excellent marker for spores of bacteria such as Anthrax.

  14. Biaxially oriented film on flexible polymeric substrate

    DOEpatents

    Finkikoglu, Alp T.; Matias, Vladimir

    2009-10-13

    A flexible polymer-based template having a biaxially oriented film grown on the surface of a polymeric substrate. The template having the biaxially oriented film can be used for further epitaxial growth of films of interest for applications such as photovoltaic cells, light emitting diodes, and the like. Methods of forming such a flexible template and providing the polymeric substrate with a biaxially oriented film deposited thereon are also described.

  15. Fermentative hydrogen production from agroindustrial lignocellulosic substrates

    PubMed Central

    Reginatto, Valeria; Antônio, Regina Vasconcellos

    2015-01-01

    To achieve economically competitive biological hydrogen production, it is crucial to consider inexpensive materials such as lignocellulosic substrate residues derived from agroindustrial activities. It is possible to use (1) lignocellulosic materials without any type of pretreatment, (2) lignocellulosic materials after a pretreatment step, and (3) lignocellulosic materials hydrolysates originating from a pretreatment step followed by enzymatic hydrolysis. According to the current literature data on fermentative H2 production presented in this review, thermophilic conditions produce H2 in yields approximately 75% higher than those obtained in mesophilic conditions using untreated lignocellulosic substrates. The average H2 production from pretreated material is 3.17 ± 1.79 mmol of H2/g of substrate, which is approximately 50% higher compared with the average yield achieved using untreated materials (2.17 ± 1.84 mmol of H2/g of substrate). Biological pretreatment affords the highest average yield 4.54 ± 1.78 mmol of H2/g of substrate compared with the acid and basic pretreatment - average yields of 2.94 ± 1.85 and 2.41 ± 1.52 mmol of H2/g of substrate, respectively. The average H2 yield from hydrolysates, obtained from a pretreatment step and enzymatic hydrolysis (3.78 ± 1.92 mmol of H2/g), was lower compared with the yield of substrates pretreated by biological methods only, demonstrating that it is important to avoid the formation of inhibitors generated by chemical pretreatments. Based on this review, exploring other microorganisms and optimizing the pretreatment and hydrolysis conditions can make the use of lignocellulosic substrates a sustainable way to produce H2. PMID:26273246

  16. Fermentative hydrogen production from agroindustrial lignocellulosic substrates.

    PubMed

    Reginatto, Valeria; Antônio, Regina Vasconcellos

    2015-06-01

    To achieve economically competitive biological hydrogen production, it is crucial to consider inexpensive materials such as lignocellulosic substrate residues derived from agroindustrial activities. It is possible to use (1) lignocellulosic materials without any type of pretreatment, (2) lignocellulosic materials after a pretreatment step, and (3) lignocellulosic materials hydrolysates originating from a pretreatment step followed by enzymatic hydrolysis. According to the current literature data on fermentative H2 production presented in this review, thermophilic conditions produce H2 in yields approximately 75% higher than those obtained in mesophilic conditions using untreated lignocellulosic substrates. The average H2 production from pretreated material is 3.17 ± 1.79 mmol of H2/g of substrate, which is approximately 50% higher compared with the average yield achieved using untreated materials (2.17 ± 1.84 mmol of H2/g of substrate). Biological pretreatment affords the highest average yield 4.54 ± 1.78 mmol of H2/g of substrate compared with the acid and basic pretreatment - average yields of 2.94 ± 1.85 and 2.41 ± 1.52 mmol of H2/g of substrate, respectively. The average H2 yield from hydrolysates, obtained from a pretreatment step and enzymatic hydrolysis (3.78 ± 1.92 mmol of H2/g), was lower compared with the yield of substrates pretreated by biological methods only, demonstrating that it is important to avoid the formation of inhibitors generated by chemical pretreatments. Based on this review, exploring other microorganisms and optimizing the pretreatment and hydrolysis conditions can make the use of lignocellulosic substrates a sustainable way to produce H2.

  17. Improved Barrier Properties in Flexible Plastic Substrates

    DTIC Science & Technology

    2009-01-01

    PolyTetraFlouro Ethylene (PTFE), PolyEthylene Terephthalate (PET) and PolyEthylene Naphthalate (PEN), the permeation rates are typically >1x103g/m2day for...of such a combination of mica and a commonly used polymer substrate PEN (Poly Ethylene Naphthalate ) to reduce the permeability of 02 and H20. Mica... Naphthalate (PEN) was used as the substrate polymer. Mica layers were stacked with the aim to increase the diffusion path length of gas molecules. The

  18. Substrates and method for determining enzymes

    DOEpatents

    Smith, Robert E.; Bissell, Eugene R.

    1981-01-01

    A method is disclosed for determining the presence of an enzyme in a biological fluid, which includes the steps of contacting the fluid with a synthetic chromogenic substrate, which is an amino acid derivative of 7-amino-4-trifluoromethylcoumarin; incubating the substrate-containing fluid to effect enzymatic hydrolysis; and fluorometrically determining the presence of the free 7-amino-4-trifluoromethylcoumarin chromophore in the hydrolyzate.

  19. Substrates and method for determining enzymes

    DOEpatents

    Smith, R.E.; Bissell, E.R.

    1981-10-13

    A method is disclosed for determining the presence of an enzyme in a biological fluid, which includes the steps of contacting the fluid with a synthetic chromogenic substrate, which is an amino acid derivative of 7-amino-4-trifluoromethylcoumarin; incubating the substrate-containing fluid to effect enzymatic hydrolysis; and fluorometrically determining the presence of the free 7-amino-4-trifluoromethylcoumarin chromophore in the hydrolyzate. No Drawings

  20. Biomechanics of substrate boring by fig wasps.

    PubMed

    Kundanati, Lakshminath; Gundiah, Namrata

    2014-06-01

    Female insects of diverse orders bore into substrates to deposit their eggs. Such insects must overcome several biomechanical challenges to successfully oviposit, which include the selection of suitable substrates through which the ovipositor can penetrate without itself fracturing. In many cases, the insect may also need to steer and manipulate the ovipositor within the substrate to deliver eggs at desired locations before rapidly retracting her ovipositor to avoid predation. In the case of female parasitoid ichneumonid wasps, this process is repeated multiple times during her lifetime, thus testing the ability of the ovipositioning apparatus to endure fracture and fatigue. What specific adaptations does the ovipositioning apparatus of a female ichneumonoid wasp possess to withstand these challenges? We addressed this question using a model system composed of parasitoid and pollinator fig wasps. First, we show that parasitoid ovipositor tips have teeth-like structures, preferentially enriched with zinc, unlike the smooth morphology of pollinator ovipositors. We describe sensillae present on the parasitoid ovipositor tip that are likely to aid in the detection of chemical species and mechanical deformations and sample microenvironments within the substrate. Second, using atomic force microscopy, we show that parasitoid tip regions have a higher modulus compared with regions proximal to the abdomen in parasitoid and pollinator ovipositors. Finally, we use videography to film wasps during substrate boring and analyse buckling of the ovipositor to estimate the forces required for substrate boring. Together, these results allow us to describe the biomechanical principles underlying substrate boring in parasitoid ichneumonid wasps. Such studies may be useful for the biomimetic design of surgical tools and in the use of novel mechanisms to bore through hard substrates.

  1. HDAC8 substrates: Histones and beyond.

    PubMed

    Wolfson, Noah A; Pitcairn, Carol Ann; Fierke, Carol A

    2013-02-01

    The lysine deacetylase family of enzymes (HDACs) was first demonstrated to catalyze deacetylation of acetyllysine residues on histones. In subsequent years, HDACs have been shown to recognize a large pool of acetylated nonhistone proteins as substrates. Recently, thousands of acetylated proteins have been discovered, yet in most cases, the HDAC that catalyzes deacetylation in vivo has not been identified. This gap has created the need for better in vivo, in vitro, and in silico approaches for determining HDAC substrates. While HDAC8 is the best kinetically and structurally characterized HDAC, few efficient substrates have yet been substantiated in vivo. In this review, we delineate factors that may be important for determining HDAC8 substrate recognition and catalytic activity, including structure, complex formation, and post-translational modifications. This summary provides insight into the challenges of identifying in vivo substrates for HDAC8, and provides a good vantage point for understanding the variables important for predicting HDAC substrate recognition. Copyright © 2012 Wiley Periodicals, Inc.

  2. Virtual substrate method for nanomaterials characterization

    PubMed Central

    Da, Bo; Liu, Jiangwei; Yamamoto, Mahito; Ueda, Yoshihiro; Watanabe, Kazuyuki; Cuong, Nguyen Thanh; Li, Songlin; Tsukagoshi, Kazuhito; Yoshikawa, Hideki; Iwai, Hideo; Tanuma, Shigeo; Guo, Hongxuan; Gao, Zhaoshun; Sun, Xia; Ding, Zejun

    2017-01-01

    Characterization techniques available for bulk or thin-film solid-state materials have been extended to substrate-supported nanomaterials, but generally non-quantitatively. This is because the nanomaterial signals are inevitably buried in the signals from the underlying substrate in common reflection-configuration techniques. Here, we propose a virtual substrate method, inspired by the four-point probe technique for resistance measurement as well as the chop-nod method in infrared astronomy, to characterize nanomaterials without the influence of underlying substrate signals from four interrelated measurements. By implementing this method in secondary electron (SE) microscopy, a SE spectrum (white electrons) associated with the reflectivity difference between two different substrates can be tracked and controlled. The SE spectrum is used to quantitatively investigate the covering nanomaterial based on subtle changes in the transmission of the nanomaterial with high efficiency rivalling that of conventional core-level electrons. The virtual substrate method represents a benchmark for surface analysis to provide ‘free-standing' information about supported nanomaterials. PMID:28548114

  3. Virtual substrate method for nanomaterials characterization

    NASA Astrophysics Data System (ADS)

    da, Bo; Liu, Jiangwei; Yamamoto, Mahito; Ueda, Yoshihiro; Watanabe, Kazuyuki; Cuong, Nguyen Thanh; Li, Songlin; Tsukagoshi, Kazuhito; Yoshikawa, Hideki; Iwai, Hideo; Tanuma, Shigeo; Guo, Hongxuan; Gao, Zhaoshun; Sun, Xia; Ding, Zejun

    2017-05-01

    Characterization techniques available for bulk or thin-film solid-state materials have been extended to substrate-supported nanomaterials, but generally non-quantitatively. This is because the nanomaterial signals are inevitably buried in the signals from the underlying substrate in common reflection-configuration techniques. Here, we propose a virtual substrate method, inspired by the four-point probe technique for resistance measurement as well as the chop-nod method in infrared astronomy, to characterize nanomaterials without the influence of underlying substrate signals from four interrelated measurements. By implementing this method in secondary electron (SE) microscopy, a SE spectrum (white electrons) associated with the reflectivity difference between two different substrates can be tracked and controlled. The SE spectrum is used to quantitatively investigate the covering nanomaterial based on subtle changes in the transmission of the nanomaterial with high efficiency rivalling that of conventional core-level electrons. The virtual substrate method represents a benchmark for surface analysis to provide `free-standing' information about supported nanomaterials.

  4. Spectrophotometric determination of substrate-borne polyacrylamide.

    PubMed

    Lu, Jianhang; Wu, Laosheng

    2002-08-28

    Polyacrylamides (PAMs) have wide application in many industries and in agriculture. Scientific research and industrial applications manifested a need for a method that can quantify substrate-borne PAM. The N-bromination method (a PAM analytical technique based on N-bromination of amide groups and spectrophotometric determination of the formed starch-triiodide complex), which was originally developed for determining PAM in aqueous solutions, was modified to quantify substrate-borne PAM. In the modified method, the quantity of substrate-borne PAM was converted to a concentration of starch-triiodide complex in aqueous solution that was then measured by spectrophotometry. The method sensitivity varied with substrates due to sorption of reagents and reaction intermediates on the substrates. Therefore, separate calibration for each substrate was required. Results from PAM samples in sand, cellulose, organic matter burnt soils, and clay minerals showed that this method had good accuracy and reproducibility. The PAM recoveries ranged from 95.8% to 103.7%, and the relative standard deviations (n = 4) were <7.5% in all cases. The optimum range of PAM in each sample is 10-80 microg. The technique can serve as an effective tool in improving PAM application and facilitating PAM-related research.

  5. Virtual substrate method for nanomaterials characterization.

    PubMed

    Da, Bo; Liu, Jiangwei; Yamamoto, Mahito; Ueda, Yoshihiro; Watanabe, Kazuyuki; Cuong, Nguyen Thanh; Li, Songlin; Tsukagoshi, Kazuhito; Yoshikawa, Hideki; Iwai, Hideo; Tanuma, Shigeo; Guo, Hongxuan; Gao, Zhaoshun; Sun, Xia; Ding, Zejun

    2017-05-26

    Characterization techniques available for bulk or thin-film solid-state materials have been extended to substrate-supported nanomaterials, but generally non-quantitatively. This is because the nanomaterial signals are inevitably buried in the signals from the underlying substrate in common reflection-configuration techniques. Here, we propose a virtual substrate method, inspired by the four-point probe technique for resistance measurement as well as the chop-nod method in infrared astronomy, to characterize nanomaterials without the influence of underlying substrate signals from four interrelated measurements. By implementing this method in secondary electron (SE) microscopy, a SE spectrum (white electrons) associated with the reflectivity difference between two different substrates can be tracked and controlled. The SE spectrum is used to quantitatively investigate the covering nanomaterial based on subtle changes in the transmission of the nanomaterial with high efficiency rivalling that of conventional core-level electrons. The virtual substrate method represents a benchmark for surface analysis to provide 'free-standing' information about supported nanomaterials.

  6. Metal ion substrate inhibition of ferrochelatase.

    PubMed

    Hunter, Gregory A; Sampson, Matthew P; Ferreira, Gloria C

    2008-08-29

    Ferrochelatase catalyzes the insertion of ferrous iron into protoporphyrin IX to form heme. Robust kinetic analyses of the reaction mechanism are complicated by the instability of ferrous iron in aqueous solution, particularly at alkaline pH values. At pH 7.00 the half-life for spontaneous oxidation of ferrous ion is approximately 2 min in the absence of metal complexing additives, which is sufficient for direct comparisons of alternative metal ion substrates with iron. These analyses reveal that purified recombinant ferrochelatase from both murine and yeast sources inserts not only ferrous iron but also divalent cobalt, zinc, nickel, and copper into protoporphyrin IX to form the corresponding metalloporphyrins but with considerable mechanistic variability. Ferrous iron is the preferred metal ion substrate in terms of apparent k(cat) and is also the only metal ion substrate not subject to severe substrate inhibition. Substrate inhibition occurs in the order Cu(2+) > Zn(2+) > Co(2+) > Ni(2+) and can be alleviated by the addition of metal complexing agents such as beta-mercaptoethanol or imidazole to the reaction buffer. These data indicate the presence of two catalytically significant metal ion binding sites that may coordinately regulate a selective processivity for the various potential metal ion substrates.

  7. Palladium clusters deposited on the heterogeneous substrates

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Liu, Juanfang; Chen, Qinghua

    2016-07-01

    To improve the performance of the Pd composite membrane prepared by the cold spraying technology, it is extremely essential to give insights into the deposition process of the cluster and the heterogeneous deposition of the big Pd cluster at the different incident velocities on the atomic level. The deposition behavior, morphologies, energetic and interfacial configuration were examined by the molecular dynamic simulation and characterized by the cluster flattening ratio, the substrate maximum local temperature, the atom-embedded layer number and the surface-alloy formation. According to the morphology evolution, three deposition stages and the corresponding structural and energy evolution were clearly identified. The cluster deformation and penetrating depth increased with the enhancement of the incident velocity, but the increase degree also depended on the substrate hardness. The interfacial interaction between the cluster and the substrate can be improved by the higher substrate local temperature. Furthermore, it is found that the surface alloys were formed by exchanging sites between the cluster and substrate atoms, and the cluster atoms rearranged following as the substrate lattice arrangement from bottom to up in the deposition course. The ability and scope of the structural reconstruction are largely determined by both the size and incident energy of the impacted cluster.

  8. Substrate-targeting gamma-secretase modulators.

    PubMed

    Kukar, Thomas L; Ladd, Thomas B; Bann, Maralyssa A; Fraering, Patrick C; Narlawar, Rajeshwar; Maharvi, Ghulam M; Healy, Brent; Chapman, Robert; Welzel, Alfred T; Price, Robert W; Moore, Brenda; Rangachari, Vijayaraghavan; Cusack, Bernadette; Eriksen, Jason; Jansen-West, Karen; Verbeeck, Christophe; Yager, Debra; Eckman, Christopher; Ye, Wenjuan; Sagi, Sarah; Cottrell, Barbara A; Torpey, Justin; Rosenberry, Terrone L; Fauq, Abdul; Wolfe, Michael S; Schmidt, Boris; Walsh, Dominic M; Koo, Edward H; Golde, Todd E

    2008-06-12

    Selective lowering of Abeta42 levels (the 42-residue isoform of the amyloid-beta peptide) with small-molecule gamma-secretase modulators (GSMs), such as some non-steroidal anti-inflammatory drugs, is a promising therapeutic approach for Alzheimer's disease. To identify the target of these agents we developed biotinylated photoactivatable GSMs. GSM photoprobes did not label the core proteins of the gamma-secretase complex, but instead labelled the beta-amyloid precursor protein (APP), APP carboxy-terminal fragments and amyloid-beta peptide in human neuroglioma H4 cells. Substrate labelling was competed by other GSMs, and labelling of an APP gamma-secretase substrate was more efficient than a Notch substrate. GSM interaction was localized to residues 28-36 of amyloid-beta, a region critical for aggregation. We also demonstrate that compounds known to interact with this region of amyloid-beta act as GSMs, and some GSMs alter the production of cell-derived amyloid-beta oligomers. Furthermore, mutation of the GSM binding site in the APP alters the sensitivity of the substrate to GSMs. These findings indicate that substrate targeting by GSMs mechanistically links two therapeutic actions: alteration in Abeta42 production and inhibition of amyloid-beta aggregation, which may synergistically reduce amyloid-beta deposition in Alzheimer's disease. These data also demonstrate the existence and feasibility of 'substrate targeting' by small-molecule effectors of proteolytic enzymes, which if generally applicable may significantly broaden the current notion of 'druggable' targets.

  9. Substrate inhibition kinetics of phenol biodegradation

    SciTech Connect

    Goudar, C.T.; Ganji, S.H.; Pujar, B.G.; Strevett, K.A.

    2000-02-01

    Phenol biodegradation was studied in batch experiments using an acclimated inoculum and initial phenol concentrations ranging from 0.1 to 1.3 g/L. Phenol depletion an associated microbial growth were monitored over time to provide information that was used to estimate the kinetics of phenol biodegradation. Phenol inhibited biodegradation at high concentrations, and a generalized substrate inhibition model based on statistical thermodynamics was used to describe the dynamics of microbial growth in phenol. For experimental data obtained in this study, the generalized substrate inhibition model reduced to a form that is analogous to the Andrews equation, and the biokinetic parameters {micro}{sub max}, maximum specific growth; K{sub s}, saturation constant; and K{sub i}, inhibition constant were estimated as 0.251 h{sup {minus}1}, 0.011 g/L, and 0.348 g/L, respectively, using a nonlinear least squares technique. Given the wide variability in substrate inhibition models used to describe phenol biodegradation, an attempt was made to justify selection of particular model based on theoretical considerations. Phenol biodegradation data from nine previously published studies were used in the generalized substrate inhibition model to determine the appropriate form of the substrate inhibition model. In all nine cases, the generalized substrate inhibition model reduced to a form analogous to the Andrews equation suggesting the suitability of the Andrews equation to describe phenol biodegradation data.

  10. Effect of polymeric substrate on sludge settleability.

    PubMed

    Martins, António M P; Karahan, Ozlem; van Loosdrecht, Mark C M

    2011-01-01

    The study aims to evaluate the role of a polymeric substrate (starch) on sludge settleability. Despite being an important COD component of the wastewater, the relationship between polymeric substrates and bulking sludge has been hardly studied. The polymers are hydrolysed at a rate smaller than the consumption rate of monomers. This means that the soluble substrate resulting from hydrolysis is likely to be present at growth rate limiting concentrations. According to the kinetic selection theory this leads to bulking sludge. However, a recently postulated theory suggests that, strong diffusion limited micro-gradients of substrate concentration inside flocs lead to bulking sludge, and not a low substrate concentration as such. If the polymeric COD is first incorporated in the sludge floc and afterwards hydrolysed in the sludge floc then there is essentially no substrate gradient inside the biological flocs. The experiments showed that conditions leading to bulking sludge with monomers (glucose) did not lead to bulking when starch was used. A bulking sludge event was even cured just by substituting the monomer with starch. These results are clearly in line with a diffusion gradient--based theory for bulking sludge. Nevertheless, flocs growing on starch are more open, fluffy and porous than flocs formed on maltose or glucose, most likely because the starch needs to be hydrolysed at the surface of the micro-colonies forming the flocculated sludge. Some additional observations on occurrence of filamentous bacteria in oxygen diffusion limited systems are also discussed in this manuscript.

  11. Cells preferentially grow on rough substrates.

    PubMed

    Gentile, Francesco; Tirinato, Luca; Battista, Edmondo; Causa, Filippo; Liberale, Carlo; di Fabrizio, Enzo M; Decuzzi, Paolo

    2010-10-01

    Substrate nanotopography affects cell adhesion and proliferation and is fundamental to the rational design of bio-adhesives, to tissue engineering and to the development of assays for in-vitro screening. Cell behavior on rough substrates is still elusive, and the results presented in the open literature remain controversial. Here, the proliferation of cells on electrochemically etched silicon substrates with different roughness and nearly similar surface energy was studied over three days with confocal and atomic force microscopy. The surface profile of the substrates is a self-affine fractal with a roughness R(a) growing with the etching time from approximately 2 to 100 nm and a fractal dimension D ranging between about 2 (nominally flat surface) and 2.6. For four cell types, the number of adhering cells and their proliferation rates exhibited a maximum on moderately rough (R(a) approximately 10-45 nm) nearly Brownian (D approximately 2.5) substrates. The observed cell behavior was satisfactorily interpreted within the theory of adhesion to randomly rough solids. These findings demonstrated the importance of nanogeometry in cell stable adhesion and growth, suggesting that moderately rough substrates with large fractal dimension could selectively boost cell proliferation.

  12. Nanomechanics of hard films on compliant substrates.

    SciTech Connect

    Reedy, Earl David, Jr.; Emerson, John Allen; Bahr, David F.; Moody, Neville Reid; Zhou, Xiao Wang; Hales, Lucas; Adams, David Price; Yeager,John; Nyugen, Thao D.; Corona, Edmundo; Kennedy, Marian S.; Cordill, Megan J.

    2009-09-01

    Development of flexible thin film systems for biomedical, homeland security and environmental sensing applications has increased dramatically in recent years [1,2,3,4]. These systems typically combine traditional semiconductor technology with new flexible substrates, allowing for both the high electron mobility of semiconductors and the flexibility of polymers. The devices have the ability to be easily integrated into components and show promise for advanced design concepts, ranging from innovative microelectronics to MEMS and NEMS devices. These devices often contain layers of thin polymer, ceramic and metallic films where differing properties can lead to large residual stresses [5]. As long as the films remain substrate-bonded, they may deform far beyond their freestanding counterpart. Once debonded, substrate constraint disappears leading to film failure where compressive stresses can lead to wrinkling, delamination, and buckling [6,7,8] while tensile stresses can lead to film fracture and decohesion [9,10,11]. In all cases, performance depends on film adhesion. Experimentally it is difficult to measure adhesion. It is often studied using tape [12], pull off [13,14,15], and peel tests [16,17]. More recent techniques for measuring adhesion include scratch testing [18,19,20,21], four point bending [22,23,24], indentation [25,26,27], spontaneous blisters [28,29] and stressed overlayers [7,26,30,31,32,33]. Nevertheless, sample design and test techniques must be tailored for each system. There is a large body of elastic thin film fracture and elastic contact mechanics solutions for elastic films on rigid substrates in the published literature [5,7,34,35,36]. More recent work has extended these solutions to films on compliant substrates and show that increasing compliance markedly changes fracture energies compared with rigid elastic solution results [37,38]. However, the introduction of inelastic substrate response significantly complicates the problem [10,39,40]. As

  13. Influence of the laser pre-quenched substrate on an electroplated chromium coating/steel substrate

    NASA Astrophysics Data System (ADS)

    Chen, Xuejun; Yan, Qian; Ma, Qian

    2017-05-01

    The chromium coatings were electroplated onto a laser pre-quenched steel substrate to improve the interfacial adhesion properties of chromium coating/steel substrate system. The influence of laser pre-treatment on the substrate, coating as well as interface was investigated by using microstructure characterization, hardness testing, tensile testing and finite element analysis. An apparent boundary line instead of an interlayer was identified between chromium coating/pre-quenched steel substrate. The Vickers hardness and yield strength of steel substrate were significantly improved after laser pre-quenching. The fracture toughness of chromium coating was increased by about 28.6% compared to the un-treated counterpart. The energy release rate for an interfacial crack in the chromium coating/laser-quenched substrate was smaller than that in the untreated specimen. These results may help understand the life prolongation mechanism for the laser pre-quenched chromium/coated steel parts.

  14. Atomically flat single terminated oxide substrate surfaces

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Yang, Chan-Ho; Ramesh, Ramamoorthy; Jeong, Yoon H.

    2017-05-01

    Scientific interest in atomically controlled layer-by-layer fabrication of transition metal oxide thin films and heterostructures has increased intensely in recent decades for basic physics reasons as well as for technological applications. This trend has to do, in part, with the coming post-Moore era, and functional oxide electronics could be regarded as a viable alternative for the current semiconductor electronics. Furthermore, the interface of transition metal oxides is exposing many new emergent phenomena and is increasingly becoming a playground for testing new ideas in condensed matter physics. To achieve high quality epitaxial thin films and heterostructures of transition metal oxides with atomically controlled interfaces, one critical requirement is the use of atomically flat single terminated oxide substrates since the atomic arrangements and the reaction chemistry of the topmost surface layer of substrates determine the growth and consequent properties of the overlying films. Achieving the atomically flat and chemically single terminated surface state of commercially available substrates, however, requires judicious efforts because the surface of as-received substrates is of chemically mixed nature and also often polar. In this review, we summarize the surface treatment procedures to accomplish atomically flat surfaces with single terminating layer for various metal oxide substrates. We particularly focus on the substrates with lattice constant ranging from 4.00 Å to 3.70 Å, as the lattice constant of most perovskite materials falls into this range. For materials outside the range, one can utilize the substrates to induce compressive or tensile strain on the films and explore new states not available in bulk. The substrates covered in this review, which have been chosen with commercial availability and, most importantly, experimental practicality as a criterion, are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3, La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), Nd

  15. Substrate specificity of cytoplasmic N-glycosyltransferase.

    PubMed

    Naegeli, Andreas; Michaud, Gaëlle; Schubert, Mario; Lin, Chia-Wei; Lizak, Christian; Darbre, Tamis; Reymond, Jean-Louis; Aebi, Markus

    2014-08-29

    N-Linked protein glycosylation is a very common post-translational modification that can be found in all kingdoms of life. The classical, highly conserved pathway entails the assembly of a lipid-linked oligosaccharide and its transfer to an asparagine residue in the sequon NX(S/T) of a secreted protein by the integral membrane protein oligosaccharyltransferase. A few species in the class of γ-proteobacteria encode a cytoplasmic N-glycosylation system mediated by a soluble N-glycosyltransferase (NGT). This enzyme uses nucleotide-activated sugars to modify asparagine residues with single monosaccharides. As these enzymes are not related to oligosaccharyltransferase, NGTs constitute a novel class of N-glycosylation catalyzing enzymes. To characterize the NGT-catalyzed reaction, we developed a sensitive and quantitative in vitro assay based on HPLC separation and quantification of fluorescently labeled substrate peptides. With this assay we were able to directly quantify glycopeptide formation by Actinobacillus pleuropneumoniae NGT and determine its substrate specificities: NGT turns over a number of different sugar donor substrates and allows for activation by both UDP and GDP. Quantitative analysis of peptide substrate turnover demonstrated a strikingly similar specificity as the classical, oligosaccharyltransferase-catalyzed N-glycosylation, with NX(S/T) sequons being the optimal NGT substrates. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Substrate Specificity of Cytoplasmic N-Glycosyltransferase*

    PubMed Central

    Naegeli, Andreas; Michaud, Gaëlle; Schubert, Mario; Lin, Chia-Wei; Lizak, Christian; Darbre, Tamis; Reymond, Jean-Louis; Aebi, Markus

    2014-01-01

    N-Linked protein glycosylation is a very common post-translational modification that can be found in all kingdoms of life. The classical, highly conserved pathway entails the assembly of a lipid-linked oligosaccharide and its transfer to an asparagine residue in the sequon NX(S/T) of a secreted protein by the integral membrane protein oligosaccharyltransferase. A few species in the class of γ-proteobacteria encode a cytoplasmic N-glycosylation system mediated by a soluble N-glycosyltransferase (NGT). This enzyme uses nucleotide-activated sugars to modify asparagine residues with single monosaccharides. As these enzymes are not related to oligosaccharyltransferase, NGTs constitute a novel class of N-glycosylation catalyzing enzymes. To characterize the NGT-catalyzed reaction, we developed a sensitive and quantitative in vitro assay based on HPLC separation and quantification of fluorescently labeled substrate peptides. With this assay we were able to directly quantify glycopeptide formation by Actinobacillus pleuropneumoniae NGT and determine its substrate specificities: NGT turns over a number of different sugar donor substrates and allows for activation by both UDP and GDP. Quantitative analysis of peptide substrate turnover demonstrated a strikingly similar specificity as the classical, oligosaccharyltransferase-catalyzed N-glycosylation, with NX(S/T) sequons being the optimal NGT substrates. PMID:24962585

  17. Colloidal Drop Deposition on Porous Substrates

    NASA Astrophysics Data System (ADS)

    Sun, Ying; Pack, Min; Hu, Han; Kim, Dong-Ook; Yang, Xin

    2015-11-01

    Printable electronics and in particular paper and textile-based electronics have fueled research in inkjet printing on porous substrates. On nonporous substrates, the particle motion of the particles and evaporation of the solvent are the two main mechanisms that drive the final deposition morphology. For porous substrates another factor, mainly infiltration, adds a layer of complexity to the deposition patterns that has not yet been elucidated in literature. In this study, a high-speed camera was used to capture the imbibition of picoliter-sized polystyrene nanoparticles in water droplets into nano-porous anodic aluminum oxide substrates of various porosities and wettabilities. For water, the infiltration rate is much faster than both evaporation and particle motion and thus when the substrate fully imbibes the droplet, the well-known ``coffee ring'' is suppressed. However, when a residual droplet forms upon the termination of the infiltration regime, the competing particle motion and evaporation regimes, tP and tEI respectively, define the critical time scales for which the coffee ring will be formed (tP /tEI <1) or suppressed (tP /tEI >1). National Science Foundation under Grant No. CMMI-1401438.

  18. Multistructural biomimetic substrates for controlled cellular differentiation

    NASA Astrophysics Data System (ADS)

    Orza, Anamaria I.; Mihu, Carmen; Soritau, Olga; Diudea, Mircea; Florea, Adrian; Matei, Horea; Balici, Stefana; Mudalige, Thilak; Kanarpardy, Ganesh K.; Biris, Alexandru S.

    2014-02-01

    Multidimensional scaffolds are considered to be ideal candidates for regenerative medicine and tissue engineering based on their potential to provide an excellent microenvironment and direct the fate of the cultured cells. More recently, the use of stem cells in medicine has opened a new technological opportunity for controlled tissue formation. However, the mechanism through which the substrate directs the differentiation of stem cells is still rather unclear. Data concerning its specific surface chemistry, topology, and its signaling ability need to be further understood and analyzed. In our study, atomic force microscopy was used to study the stiffness, roughness, and topology of the collagen (Coll) and metallized collagen (MC) substrates, proposed as an excellent substrate for regenerative medicine. The importance of signaling molecules was studied by constructing a new hybrid signaling substrate that contains both collagen and laminin extracellular matrix (ECM) proteins. The cellular response—such as attachment capability, proliferation and cardiac and neuronal phenotype expression on the metallized and non-metallized hybrid substrates (collagen + laminin)—was studied using MTT viability assay and immunohistochemistry studies. Our findings indicate that such hybrid materials could play an important role in the regeneration of complex tissues.

  19. Wetting and electrowetting on corrugated substrates

    NASA Astrophysics Data System (ADS)

    Wang, Zhanlong; Zhao, Ya-Pu

    2017-06-01

    Wetting and electrowetting (EW) on corrugated substrates are studied experimentally and theoretically in this paper. On corrugated substrates, because of the anisotropy of surface morphology, the droplet shows an elliptical shape and the spreading velocities in different directions are different. Spreading of a droplet is usually controlled not only by the surface tensions but also by hemi-wicking. Our experimental results indicated that liquids along the grooves propagate much faster than those in the direction vertical to the grooves. However, spreading in both directions obeys the same scaling law of l ˜t4 /5. EW on corrugated substrates reveals some differences with that on smooth surfaces. The change of contact angles with an applied voltage follows a linear relationship in two stages instead of the smooth curve on flat surfaces. There exists a critical voltage which divides the two stages. The transition of a droplet from the Cassie state to the Wenzel state on corrugated substrates was also discussed. The extended EW equation was derived with the free energy minimization approach, and the anisotropic factor was introduced. From the extended equation, it is found that EW is affected by the anisotropic factor significantly. For the smooth surfaces, the extended EW equation will degenerate to the classical Lippmann-Young equation. Our research may help us to understand the wetting and EW of droplets on corrugated substrates and assist in their design for practical applications.

  20. Review of SERS Substrates for Chemical Sensing

    PubMed Central

    Mosier-Boss, Pamela A.

    2017-01-01

    The SERS effect was initially discovered in the 1970s. Early research focused on understanding the phenomenon and increasing enhancement to achieve single molecule detection. From the mid-1980s to early 1990s, research started to move away from obtaining a fundamental understanding of the phenomenon to the exploration of analytical applications. At the same time, significant developments occurred in the field of photonics that led to the advent of inexpensive, robust, compact, field-deployable Raman systems. The 1990s also saw rapid development in nanoscience. This convergence of technologies (photonics and nanoscience) has led to accelerated development of SERS substrates to detect a wide range of chemical and biological analytes. It would be a monumental task to discuss all the different kinds of SERS substrates that have been explored. Likewise, it would be impossible to discuss the use of SERS for both chemical and biological detection. Instead, a review of the most common metallic (Ag, Cu, and Au) SERS substrates for chemical detection only is discussed, as well as SERS substrates that are commercially available. Other issues with SERS for chemical detection have been selectivity, reversibility, and reusability of the substrates. How these issues have been addressed is also discussed in this review. PMID:28594385

  1. Modular composition predicts kinase/substrate interactions

    PubMed Central

    2010-01-01

    Background Phosphorylation events direct the flow of signals and metabolites along cellular protein networks. Current annotations of kinase-substrate binding events are far from complete. In this study, we scanned the entire human protein sequences using the PROSITE domain annotation tool to identify patterns of domain composition in kinases and their substrates. We identified statistically enriched pairs of strings of domains (signature pairs) in kinase-substrate couples presented in the 2006 version of the PTM database. Results The signature pairs enriched in kinase - substrate binding interactions turned out to be highly specific to kinase subtypes. The resulting list of signature pairs predicted kinase-substrate interactions in validation dataset not used in learning with high statistical accuracy. Conclusions The method presented here produces predictions of protein phosphorylation events with high accuracy and mid-level coverage. Our method can be used in expanding the currently available drafts of cell signaling pathways and thus will be an important tool in the development of combination drug therapies targeting complex diseases. PMID:20579376

  2. The Structural Basis of Sirtuin Substrate Affinity

    SciTech Connect

    Cosgrove,M.; Bever, K.; Avalos, J.; Muhammad, S.; Zhang, X.; Wolberger, C.

    2006-01-01

    Sirtuins comprise a family of enzymes that catalyze the deacetylation of acetyllysine side chains in a reaction that consumes NAD+. Although several crystal structures of sirtuins bound to non-native acetyl peptides have been determined, relatively little about how sirtuins discriminate among different substrates is understood. We have carried out a systematic structural and thermodynamic analysis of several peptides bound to a single sirtuin, the Sir2 homologue from Thermatoga maritima (Sir2Tm). We report structures of five different forms of Sir2Tm: two forms bound to the p53 C-terminal tail in the acetylated and unacetylated states, two forms bound to putative acetyl peptide substrates derived from the structured domains of histones H3 and H4, and one form bound to polypropylene glycol (PPG), which resembles the apoenzyme. The structures reveal previously unobserved complementary side chain interactions between Sir2Tm and the first residue N-terminal to the acetyllysine (position -1) and the second residue C-terminal to the acetyllysine (position +2). Isothermal titration calorimetry was used to compare binding constants between wild-type and mutant forms of Sir2Tm and between additional acetyl peptide substrates with substitutions at positions -1 and +2. The results are consistent with a model in which peptide positions -1 and +2 play a significant role in sirtuin substrate binding. This model provides a framework for identifying sirtuin substrates.

  3. Multifunctionality is affected by interactions between green roof plant species, substrate depth, and substrate type.

    PubMed

    Dusza, Yann; Barot, Sébastien; Kraepiel, Yvan; Lata, Jean-Christophe; Abbadie, Luc; Raynaud, Xavier

    2017-04-01

    Green roofs provide ecosystem services through evapotranspiration and nutrient cycling that depend, among others, on plant species, substrate type, and substrate depth. However, no study has assessed thoroughly how interactions between these factors alter ecosystem functions and multifunctionality of green roofs. We simulated some green roof conditions in a pot experiment. We planted 20 plant species from 10 genera and five families (Asteraceae, Caryophyllaceae, Crassulaceae, Fabaceae, and Poaceae) on two substrate types (natural vs. artificial) and two substrate depths (10 cm vs. 30 cm). As indicators of major ecosystem functions, we measured aboveground and belowground biomasses, foliar nitrogen and carbon content, foliar transpiration, substrate water retention, and dissolved organic carbon and nitrates in leachates. Interactions between substrate type and depth strongly affected ecosystem functions. Biomass production was increased in the artificial substrate and deeper substrates, as was water retention in most cases. In contrast, dissolved organic carbon leaching was higher in the artificial substrates. Except for the Fabaceae species, nitrate leaching was reduced in deep, natural soils. The highest transpiration rates were associated with natural soils. All functions were modulated by plant families or species. Plant effects differed according to the observed function and the type and depth of the substrate. Fabaceae species grown on natural soils had the most noticeable patterns, allowing high biomass production and high water retention but also high nitrate leaching from deep pots. No single combination of factors enhanced simultaneously all studied ecosystem functions, highlighting that soil-plant interactions induce trade-offs between ecosystem functions. Substrate type and depth interactions are major drivers for green roof multifunctionality.

  4. Silica substrate or portion formed from oxidation of monocrystalline silicon

    DOEpatents

    Matzke, Carolyn M.; Rieger, Dennis J.; Ellis, Robert V.

    2003-07-15

    A method is disclosed for forming an inclusion-free silica substrate using a monocrystalline silicon substrate as the starting material and oxidizing the silicon substrate to convert it entirely to silica. The oxidation process is performed from both major surfaces of the silicon substrate using a conventional high-pressure oxidation system. The resulting product is an amorphous silica substrate which is expected to have superior etching characteristics for microfabrication than conventional fused silica substrates. The present invention can also be used to convert only a portion of a monocrystalline silicon substrate to silica by masking the silicon substrate and locally thinning a portion the silicon substrate prior to converting the silicon portion entirely to silica. In this case, the silica formed by oxidizing the thinned portion of the silicon substrate can be used, for example, as a window to provide optical access through the silicon substrate.

  5. DNAJs: more than substrate delivery to HSPA

    PubMed Central

    Dekker, Suzanne L.; Kampinga, Harm H.; Bergink, Steven

    2015-01-01

    Proteins are essential components of cellular life, as building blocks, but also to guide and execute all cellular processes. Proteins require a three-dimensional folding, which is constantly being challenged by their environment. Challenges including elevated temperatures or redox changes can alter this fold and result in misfolding of proteins or even aggregation. Cells are equipped with several pathways that can deal with protein stress. Together, these pathways are referred to as the protein quality control network. The network comprises degradation and (re)folding pathways that are intertwined due to the sharing of components and by the overlap in affinity for substrates. Here, we will give examples of this sharing and intertwinement of protein degradation and protein folding and discuss how the fate of a substrate is determined. We will focus on the ubiquitylation of substrates and the role of Hsp70 co-chaperones of the DNAJ class in this process. PMID:26176011

  6. GENE REGULATION BY MAPK SUBSTRATE COMPETITION

    PubMed Central

    Kim, Yoosik; Andreu, María José; Lim, Bomyi; Chung, Kwanghun; Terayama, Mark; Jiménez, Gerardo; Berg, Celeste A.; Lu, Hang; Shvartsman, Stanislav Y.

    2011-01-01

    SUMMARY Developing tissues are patterned by coordinated activities of signaling systems, which can be integrated by a regulatory region of a gene that binds multiple transcription factors or by a transcription factor that is modified by multiple enzymes. Based on a combination of genetic and imaging experiments in the early Drosophila embryo, we describe a signal integration mechanism that cannot be reduced to a single gene regulatory element or a single transcription factor. This mechanism relies on an enzymatic network formed by Mitogen Activated Protein Kinase (MAPK) and its substrates. Specifically, anteriorly localized MAPK substrates, such as Bicoid, antagonize MAPK-dependent downregulation of Capicua, a repressor which is involved in gene regulation along the dorsoventral axis of the embryo. MAPK substrate competition provides a basis for ternary interaction of the anterior, dorsoventral, and terminal patterning systems. A mathematical model of this interaction can explain gene expression patterns with both anteroposterior and dorsoventral polarities. PMID:21664584

  7. On Substrate for Atomic Chain Electronics

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Bauschlicher, Charles W., Jr.; Partridge, Harry; Saini, Subhash (Technical Monitor)

    1998-01-01

    A substrate for future atomic chain electronics, where adatoms are placed at designated positions and form atomically precise device components, is studied theoretically. The substrate has to serve as a two-dimensional template for adatom mounting with a reasonable confinement barrier and also provide electronic isolation, preventing unwanted coupling between independent adatom structures. However, the two requirements conflict. For excellent electronic isolation, we may seek adatom confinement via van der Waals interaction without chemical bonding to the substrate atoms, but the confinement turns out to be very weak and hence unsatisfactory. An alternative chemical bonding scheme with excellent structural strength is examined, but even fundamental adatom chain properties such as whether chains are semiconducting or metallic are strongly influenced by the nature of the chemical bonding, and electronic isolation is not always achieved. Conditions for obtaining semiconducting chains with well-localized surface-modes, leading to good isolation, are clarified and discussed.

  8. Plasma jet printing for flexible substrates

    NASA Astrophysics Data System (ADS)

    Gandhiraman, Ram P.; Singh, Eric; Diaz-Cartagena, Diana C.; Nordlund, Dennis; Koehne, Jessica; Meyyappan, M.

    2016-03-01

    Recent interest in flexible electronics and wearable devices has created a demand for fast and highly repeatable printing processes suitable for device manufacturing. Robust printing technology is critical for the integration of sensors and other devices on flexible substrates such as paper and textile. An atmospheric pressure plasma-based printing process has been developed to deposit different types of nanomaterials on flexible substrates. Multiwalled carbon nanotubes were deposited on paper to demonstrate site-selective deposition as well as direct printing without any type of patterning. Plasma-printed nanotubes were compared with non-plasma-printed samples under similar gas flow and other experimental conditions and found to be denser with higher conductivity. The utility of the nanotubes on the paper substrate as a biosensor and chemical sensor was demonstrated by the detection of dopamine, a neurotransmitter, and ammonia, respectively.

  9. Printed electronic on flexible and glass substrates

    NASA Astrophysics Data System (ADS)

    Futera, Konrad; Jakubowska, Małgorzata; Kozioł, Grażyna

    2010-09-01

    Organic electronics is a platform technology that enables multiple applications based on organic electronics but varied in specifications. Organic electronics is based on the combination of new materials and cost-effective, large area production processes that provide new fields of application. Organic electronic by its size, weight, flexibility and environmental friendliness electronics enables low cost production of numerous electrical components and provides for such promising fields of application as: intelligent packaging, low cost RFID, flexible solar cells, disposable diagnostic devices or games, and printed batteries [1]. The paper presents results of inkjetted electronics elements on flexible and glass substrates. The investigations was target on characterizing shape, surface and geometry of printed structures. Variety of substrates were investigated, within some, low cost, non specialized substrate, design for other purposes than organic electronic.

  10. Ventricular tachycardia in ischemic heart disease substrates

    PubMed Central

    Ajijola, Olujimi A.; Tung, Roderick; Shivkumar, Kalyanam

    2014-01-01

    Advances in the treatment of myocardial infarction (MI) have improved survival after ischemic cardiac injury. Post-infarct structural and functional remodeling results in electrophysiologic substrates at risk for monomorphic ventricular tachycardia (MMVT). Characterization of this substrate using a variety of clinical and investigative tools has improved our understanding of MMVT circuits, and has accelerated the development of device and catheter-based therapies aimed at identification and elimination of this arrhythmia. This review will discuss the central role of the ischemic heart disease substrate in the development MMVT. Electrophysiologic characterization of the post-infarct myocardium using bipolar electrogram amplitudes to delineate scar border zones will be reviewed. Functional electrogram determinants of reentrant circuits such as isolated late potentials will be discussed. Strategies for catheter ablation of reentrant ventricular tachycardia, including structural and functional targets will also be examined, as will the role of the epicardial mapping and ablation in the management of recurrent MMVT. PMID:24568826

  11. Substrate recognition by ribonucleoprotein ribonuclease MRP.

    PubMed

    Esakova, Olga; Perederina, Anna; Quan, Chao; Berezin, Igor; Krasilnikov, Andrey S

    2011-02-01

    The ribonucleoprotein complex ribonuclease (RNase) MRP is a site-specific endoribonuclease essential for the survival of the eukaryotic cell. RNase MRP closely resembles RNase P (a universal endoribonuclease responsible for the maturation of the 5' ends of tRNA) but recognizes distinct substrates including pre-rRNA and mRNA. Here we report the results of an in vitro selection of Saccharomyces cerevisiae RNase MRP substrates starting from a pool of random sequences. The results indicate that RNase MRP cleaves single-stranded RNA and is sensitive to sequences in the immediate vicinity of the cleavage site requiring a cytosine at the position +4 relative to the cleavage site. Structural implications of the differences in substrate recognition by RNases P and MRP are discussed.

  12. Methods for patterned deposition on a substrate

    DOEpatents

    Rye, R.R.; Ricco, A.J.; Hampden-Smith, M.J.; Kodas, T.T.

    1995-01-10

    A method is described for patterned depositions of a material onto a substrate. A surface of a polymeric substrate is first etched so as to form an etched layer having enhanced adhesions characteristics and then selected portions of the etched layer are removed so as to define a pattern having enhanced and diminished adhesion characteristics for the deposition of a conductor onto the remaining etched layer. In one embodiment, a surface of a PTFE substrate is chemically etched so as to improve the adhesion of copper thereto. Thereafter, selected portions of the etched surface are irradiated with a laser beam so as to remove the etched selected portions of the etched surface and form patterns of enhanced and diminished adhesion of copper thereto. 5 figures.

  13. Methods for patterned deposition on a substrate

    DOEpatents

    Rye, Robert R.; Ricco, Antonio J.; Hampden-Smith, M. J.; Kodas, T. T.

    1995-01-01

    A method is described for patterned depositions of a material onto a substrate. A surface of a polymeric substrate is first etched so as to form an etched layer having enhanced adhesions characteristics and then selected portions of the etched layer are removed so as to define a pattern having enhanced and diminished adhesion characteristics for the deposition of a conductor onto the remaining etched layer. In one embodiment, a surface of a PTFE substrate is chemically etched so as to improve the adhesion of copper thereto. Thereafter, selected portions of the etched surface are irradiated with a laser beam so as to remove the etched selected portions of the etched surface and form patterns of enhanced and diminished adhesion of copper thereto.

  14. Holographic fabrication of gratings in metal substrates

    NASA Technical Reports Server (NTRS)

    Fletcher, R. M.; Wagner, D. K.; Ballantyne, J. M.

    1982-01-01

    A program for investigating the grain enlargement resulting from the laser recrystallization of a thin gallium arsenide film on a patterned substrate, a technique known as graphoepitaxy was evaluated. More specifically, the effects of recrystallizing an uncapped gallium arsenide film using a continuous wave neodymium YAG laser operating at 1.06 microns were studied. In an effort to minimize arsenic loss from the film, the specimens were held in an arsine atmosphere during recrystallization. Two methods for fabricating patterned substrates were developed, one using reactive ion etching of a molybdenum film on both sapphire and silicon substates and another by preferential wet etching of a silicon substrate onto which a film of molybdenum was subsequently deposited.

  15. Plasma jet printing for flexible substrates

    SciTech Connect

    Gandhiraman, Ram P.; Singh, Eric; Diaz-Cartagena, Diana C.; Koehne, Jessica; Meyyappan, M.; Nordlund, Dennis

    2016-03-21

    Recent interest in flexible electronics and wearable devices has created a demand for fast and highly repeatable printing processes suitable for device manufacturing. Robust printing technology is critical for the integration of sensors and other devices on flexible substrates such as paper and textile. An atmospheric pressure plasma-based printing process has been developed to deposit different types of nanomaterials on flexible substrates. Multiwalled carbon nanotubes were deposited on paper to demonstrate site-selective deposition as well as direct printing without any type of patterning. Plasma-printed nanotubes were compared with non-plasma-printed samples under similar gas flow and other experimental conditions and found to be denser with higher conductivity. The utility of the nanotubes on the paper substrate as a biosensor and chemical sensor was demonstrated by the detection of dopamine, a neurotransmitter, and ammonia, respectively.

  16. Attaching of strain gages to substrates

    NASA Astrophysics Data System (ADS)

    Lemcoe, M. M.; Pattee, H. E.

    1980-03-01

    A method and apparatus for attaching strain gages to substrates is described. A strain gage having a backing plate is attached to a substrate by using a foil of brazing material between the backing plate and substrate. A pair of electrodes that are connected to a current source, are applied to opposite sides of the backing plate, so that heating of the structure occurs primarily along the relatively highly conductive foil of brazing material. Field installations are facilitated by utilizing a backing plate with wings extending at an upward incline from either side of the backing plate, by attaching the electrodes to the wings to perform the brazing operation, and by breaking off the wings after the brazing is completed.

  17. Methods of selectively incorporating metals onto substrates

    DOEpatents

    Ernst; Richard D. , Eyring; Edward M. , Turpin; Gregory C. , Dunn; Brian C.

    2008-09-30

    A method for forming multi-metallic sites on a substrate is disclosed and described. A substrate including active groups such as hydroxyl can be reacted with a pretarget metal complex. The target metal attached to the active group can then be reacted with a secondary metal complex such that an oxidation-reduction (redox) reaction occurs to form a multi-metallic species. The substrate can be a highly porous material such as aerogels, xerogels, zeolites, and similar materials. Additional metal complexes can be reacted to increase catalyst loading or control co-catalyst content. The resulting compounds can be oxidized to form oxides or reduced to form metals in the ground state which are suitable for practical use.

  18. Attaching of strain gages to substrates

    NASA Technical Reports Server (NTRS)

    Lemcoe, M. M.; Pattee, H. E. (Inventor)

    1980-01-01

    A method and apparatus for attaching strain gages to substrates is described. A strain gage having a backing plate is attached to a substrate by using a foil of brazing material between the backing plate and substrate. A pair of electrodes that are connected to a current source, are applied to opposite sides of the backing plate, so that heating of the structure occurs primarily along the relatively highly conductive foil of brazing material. Field installations are facilitated by utilizing a backing plate with wings extending at an upward incline from either side of the backing plate, by attaching the electrodes to the wings to perform the brazing operation, and by breaking off the wings after the brazing is completed.

  19. Adhesion of polyimides to aluminum substrates

    SciTech Connect

    Weaver, S.T.; Dillingham, R.G.; Boerio, F.J.; Jayaraman, N.

    1996-12-31

    Numerous investigations have been reported of thin films formed by spin-coating the polyamic acid of PMDA/ODA onto metal surfaces and heat-treating the films to obtain the polyimide. Several reports have also appeared in which solventless polyimide films formed by vapor co-deposition of PMDA and ODA onto metallic and semiconductor substrates have been described. Considerable progress has been made in determining the structure of films formed by polyamic acids which are spin-coated onto metal substrates and thermally imidized. However, many key questions remain, particularly regarding the effect of processing variables on the molecular structure and properties of polyimide films. The goal of this investigation was to relate the interfacial fracture energy of polyimide films deposited onto aluminum substrates to the molecular structure of the films.

  20. Passivation coating for flexible substrate mirrors

    DOEpatents

    Tracy, C. Edwin; Benson, David K.

    1990-01-01

    A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate before metal deposition thereon to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors. Also, the silver or other reflective metal layer on mirrors comprising thin, lightweight, flexible substrates of metal or polymer sheets coated with glassy layers can be protected with silicon nitride according to this invention.

  1. Substrate ectodomain is critical for substrate preference and inhibition of γ-secretase

    PubMed Central

    Funamoto, Satoru; Sasaki, Toru; Ishihara, Seiko; Nobuhara, Mika; Nakano, Masaki; Watanabe-Takahashi, Miho; Saito, Takashi; Kakuda, Nobuto; Miyasaka, Tomohiro; Nishikawa, Kiyotaka; Saido, Takaomi C.; Ihara, Yasuo

    2013-01-01

    Understanding the substrate recognition mechanism of γ-secretase is a key step for establishing substrate-specific inhibition of amyloid β-protein (Aβ) production. However, it is widely believed that γ-secretase is a promiscuous protease and that its substrate-specific inhibition is elusive. Here we show that γ-secretase distinguishes the ectodomain length of substrates and preferentially captures and cleaves substrates containing a short ectodomain. We also show that a subset of peptides containing the CDCYCxxxxCxCxSC motif binds to the amino terminus of C99 and inhibits Aβ production in a substrate-specific manner. Interestingly, these peptides suppress β-secretase-dependent cleavage of APP, but not that of sialyltransferase 1. Most importantly, intraperitoneal administration of peptides into mice results in a significant reduction in cerebral Aβ levels. This report provides direct evidence of the substrate preference of γ-secretase and its mechanism. Our results demonstrate that the ectodomain of C99 is a potent target for substrate-specific anti-Aβ therapeutics to combat Alzheimer’s disease. PMID:24108142

  2. Nicastrin functions to sterically hinder γ-secretase–substrate interactions driven by substrate transmembrane domain

    PubMed Central

    Bolduc, David M.; Montagna, Daniel R.; Gu, Yongli; Selkoe, Dennis J.; Wolfe, Michael S.

    2016-01-01

    γ-Secretase is an intramembrane-cleaving protease that processes many type-I integral membrane proteins within the lipid bilayer, an event preceded by shedding of most of the substrate’s ectodomain by α- or β-secretases. The mechanism by which γ-secretase selectively recognizes and recruits ectodomain-shed substrates for catalysis remains unclear. In contrast to previous reports that substrate is actively recruited for catalysis when its remaining short ectodomain interacts with the nicastrin component of γ-secretase, we find that substrate ectodomain is entirely dispensable for cleavage. Instead, γ-secretase–substrate binding is driven by an apparent tight-binding interaction derived from substrate transmembrane domain, a mechanism in stark contrast to rhomboid—another family of intramembrane-cleaving proteases. Disruption of the nicastrin fold allows for more efficient cleavage of substrates retaining longer ectodomains, indicating that nicastrin actively excludes larger substrates through steric hindrance, thus serving as a molecular gatekeeper for substrate binding and catalysis. PMID:26699478

  3. Epitaxy on Substrates with Hexagonal Lattice Symmetry.

    NASA Astrophysics Data System (ADS)

    Braun, Max Willi Hermann

    A general description of epitaxy between thin films and substrates of general symmetry was developed from a model with rigid substrate and overgrowth and extended to include strain of the overgrowth. The overgrowth-substrate interaction was described by Fourier series, usually truncated, defined on the reciprocal lattice of the interface surfaces of the crystals. Energy considerations lead directly to a criterion that epitaxial configurations occur when a pair of surface reciprocal lattice vectors of the substrate and overgrowth coincide, equivalent to atomic row matching. This is analogous to the von Laue criterion and Bragg equations of diffraction theory, with a geometrical realization related to the Ewald construction. When generalized, misfit strain, the spacing, line sense and Burgers vectors of misfit dislocations and misfit verniers are obtained from the reciprocal lattices of crystals with any symmetry and misfit. The most general structures can be described with convenient unit cells by using structure factors. Homogeneous misfit strain, the interfacial atom positions after local relaxation and misfit and elastic (harmonic approximation) strain energies were obtained by direct minimization of the total interfacial energy of a large (1105 atoms), but finite, system. The local relaxation was calculated with a Finite Element formulation. Systems with fcc {111 } or bcc{ 110} overgrowths on fcc {111} or hcp{0001} substrates were studied with respect to substrate symmetry, overgrowth size and anisotropy of the overgrowth elastic constants. Configurations such as Kurdjumov-Sachs (KS), Nishiyama-Wassermann (NW) and a pseudomorphic phase (2DC) were explained, while several other higher order configurations were predicted. The inherent difference in nature between the KS and NW and their relationship to the 2DC were emphasized. Deviations from the ideal orientation of KS linked to anisotropy for systems undergoing misfit strain were discovered. Deviations were also

  4. Direct-Cooled Power Electronics Substrate

    SciTech Connect

    Wiles, R.; Ayers, C.; Wereszczak, A.

    2008-12-23

    The goal of the Direct-Cooled Power Electronics Substrate project is to reduce the size and weight of the heat sink for power electronics used in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). The concept proposed in this project was to develop an innovative power electronics mounting structure, model it, and perform both thermal and mechanical finite-element analysis (FEA). This concept involved integrating cooling channels within the direct-bonded copper (DBC) substrate and strategically locating these channels underneath the power electronic devices. This arrangement would then be directly cooled by water-ethylene glycol (WEG), essentially eliminating the conventional heat sink and associated heat flow path. The concept was evaluated to determine its manufacturability, its compatibility with WEG, and the potential to reduce size and weight while directly cooling the DBC and associated electronics with a coolant temperature of 105 C. This concept does not provide direct cooling to the electronics, only direct cooling inside the DBC substrate itself. These designs will take into account issues such as containment of the fluid (separation from the electronics) and synergy with the whole power inverter design architecture. In FY 2008, mechanical modeling of substrate and inverter core designs as well as thermal and mechanical stress FEA modeling of the substrate designs was performed, along with research into manufacturing capabilities and methods that will support the substrate designs. In FY 2009, a preferred design(s) will be fabricated and laboratory validation testing will be completed. In FY 2010, based on the previous years laboratory testing, the mechanical design will be modified and the next generation will be built and tested in an operating inverter prototype.

  5. Pentamines as substrate for human spermine oxidase

    PubMed Central

    Takao, Koichi; Shirahata, Akira; Samejima, Keijiro; Casero, Robert A.; Igarashi, Kazuei; Sugita, Yoshiaki

    2013-01-01

    Substrate activities of various linear polyamines to human spermine oxidase (hSMO) were investigated. The activities were evaluated by monitoring the amount of H2O2 released from sample polyamines by hSMO. H2O2 was measured by a HPLC method that analyzed fluorescent dimers derived from the oxidation of homovanillic acid in the presence of horseradish peroxidase. Six triamines were tested and were found not to be hSMO substrates. Of sixteen tetramines tested, spermine (Spm) was the most active substrate, followed by homospermine and N-butylated Spm. Pentamines showed a characteristic pattern of substrate activity. Of thirteen pentamines tested, 3343 showed higher substrate activity than Spm, and 4343 showed similar activity to Spm. The activities of the other pentamines were as follows: 3443, 4443, 4344, 3344, 4334, 4444, and 3334 (in decreasing order). Product amines released from these pentamines by hSMO were then analyzed by HPLC. Triamine was the only observed product, and the amount of triamine was nearly equivalent to that of released H2O2. A marked difference in the pH dependency curves between tetramines and pentamines suggested that hSMO favored reactions with a non-protonated secondary nitrogen at the cleavage site. The Km and Vmax values for Spm and 3343 at pH 7.0 and 9.0 were consistent with the higher substrate activity of 3343 compared to Spm, as well as with the concept of a non-protonated secondary nitrogen at the cleavage site being preferred, and 3343 was well degraded at a physiological pH by hSMO. PMID:23449327

  6. QM/MM Studies Reveal How Substrate-Substrate and Enzyme-Substrate Interactions Modulate Retaining Glycosyltransferases Catalysis and Mechanism.

    PubMed

    Gómez, Hansel; Mendoza, Fernanda; Lluch, José M; Masgrau, Laura

    2015-01-01

    Glycosyltransferases (GTs) catalyze the biosynthesis of glycosidic linkages by transferring a monosaccharide from a nucleotide sugar donor to an acceptor substrate, and they do that with exquisite regio- and stereospecificity. Retaining GTs act with retention of the configuration at the anomeric carbon of the transferred sugar. Their chemical mechanism has been under debate for long as conclusive experimental data to confirm the mechanism have been elusive. In the past years, quantum mechanical/molecular mechanical (QM/MM) calculations have shed light on the mechanistic discussion. Here, we review the work carried out in our group investigating three of these retaining enzymes (LgtC, α3GalT, and GalNAc-T2). Our results support the controversial front-side attack mechanism as the general mechanism for most retaining GTs. The latest structural data are in agreement with these findings. QM/MM calculations have revealed how enzyme-substrate and substrate-substrate interactions modulate the transfer reaction catalyzed by these enzymes. Moreover, they provide an explanation on why in some cases a strong nucleophilic residue is found on the β-face of the sugar, opening the door to a shift toward a double-displacement mechanism.

  7. RF Transmission Lines on Silicon Substrates

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.

    1999-01-01

    A review of RF transmission lines on silicon substrates is presented. Through measurements and calculated results, it is shown that attenuation is dominated by conductor loss if silicon substrates with a resistivity greater than 2500 Ohm-cm are used. Si passivation layers affect the transmission line attenuation; however, measured results demonstrate that passivation layers do not necessarily increase attenuation. If standard, low resistivity Si wafers must be used, alternative transmission lines such as thin film microstrip and Co-Planar Waveguide (CPW) on thick polyimide layers must be used. Measured results presented here show that low loss per unit length is achievable with these transmission lines.

  8. Hybrid stretchable circuits on silicone substrate

    SciTech Connect

    Robinson, A. Aziz, A.; Liu, Q.; Suo, Z.; Lacour, S. P.

    2014-04-14

    When rigid and stretchable components are integrated onto a single elastic carrier substrate, large strain heterogeneities appear in the vicinity of the deformable-non-deformable interfaces. In this paper, we report on a generic approach to manufacture hybrid stretchable circuits where commercial electronic components can be mounted on a stretchable circuit board. Similar to printed circuit board development, the components are electrically bonded on the elastic substrate and interconnected with stretchable electrical traces. The substrate—a silicone matrix carrying concentric rigid disks—ensures both the circuit elasticity and the mechanical integrity of the most fragile materials.

  9. Method of applying coatings to substrates

    DOEpatents

    Hendricks, Charles D.

    1991-01-01

    A method for applying novel coatings to substrates is provided. The ends of multiplicity of rods of different materials are melted by focused beams of laser light. Individual electric fields are applied to each of the molten rod ends, thereby ejecting charged particles that include droplets, atomic clusters, molecules, and atoms. The charged particles are separately transported, by the accelerations provided by electric potentials produced by an electrode structure, to substrates where they combine and form the coatings. Layered and thickness graded coatings comprised of hithereto unavailable compositions, are provided.

  10. Graphene nanoribbon electrical decoupling from metallic substrates.

    PubMed

    Borriello, Ivo; Cantele, Giovanni; Ninno, Domenico

    2013-01-07

    We address the structural and electronic properties of graphene nanoribbons (GNRs) covalently immobilized on a metallic substrate by means of an organic layer. The GNR-organic layer and organic layer-metal interfaces can be thought of as constituents of a nanodevice and have been accurately studied using large-scale density functional theory calculations. Our results demonstrate the possibility of combining nanopatterned metal-organic layer substrates with selected GNRs to obtain well ordered and stable structures while preserving the GNR energy band gap, an essential requirement for any switching nanodevice.

  11. Thin film photovoltaic device with multilayer substrate

    DOEpatents

    Catalano, Anthony W.; Bhushan, Manjul

    1984-01-01

    A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

  12. Cleaning process for EUV optical substrates

    SciTech Connect

    Weber, F.J.; Spiller, E.A.

    1999-09-28

    A cleaning process is disclosed for surfaces with very demanding cleanliness requirements, such as extreme-ultraviolet (EUV) optical substrates. Proper cleaning of optical substrates prior to applying reflective coatings thereon is very critical in the fabrication of the reflective optics used in EUV lithographic systems, for example. The cleaning process involves ultrasonic cleaning in acetone, methanol, and a pH neutral soap, such as FL-70, followed by rinsing in de-ionized water and drying with dry filtered nitrogen in conjunction with a spin-rinse.

  13. Cleaning process for EUV optical substrates

    DOEpatents

    Weber, Frank J.; Spiller, Eberhard A.

    1999-01-01

    A cleaning process for surfaces with very demanding cleanliness requirements, such as extreme-ultraviolet (EUV) optical substrates. Proper cleaning of optical substrates prior to applying reflective coatings thereon is very critical in the fabrication of the reflective optics used in EUV lithographic systems, for example. The cleaning process involves ultrasonic cleaning in acetone, methanol, and a pH neutral soap, such as FL-70, followed by rinsing in de-ionized water and drying with dry filtered nitrogen in conjunction with a spin-rinse.

  14. Polysilicon TFT fabrication on plastic substrates

    SciTech Connect

    Carey, P.G.; Smith, P.M.; Wickboldt, P.W.; Thompson, M.O.; Sigmon, T.W.

    1997-08-06

    Processing techniques utilizing low temperature depositions and pulsed lasers allow the fabrication of polysilicon thin film transistors (TFT`s) on plastic substrates. By limiting the silicon, SiO2, and aluminum deposition temperatures to 100(degrees)C, and by using pulsed laser crystallization and doping of the silicon, we have demonstrated functioning polysilicon TFT`s fabricated on polyester substrates with channel mobilities of up to 7.5 cm2/V-sec and Ion/Ioff current ratios of up to 1x10(to the 6th power).

  15. Spreading of liquid drops over porous substrates.

    PubMed

    Starov, V M; Zhdanov, S A; Kosvintsev, S R; Sobolev, V D; Velarde, M G

    2003-07-01

    The spreading of small liquid drops over thin and thick porous layers (dry or saturated with the same liquid) has been investigated in the case of both complete wetting (silicone oils of different viscosities) and partial wetting (aqueous SDS solutions of different concentrations). Nitrocellulose membranes of different porosity and different average pore size have been used as a model of thin porous layers, glass and metal filters have been used as a model of thick porous substrates. The first problem under investigation has been the spreading of small liquid drops over thin porous layers saturated with the same liquid. An evolution equation describing the drop spreading has been deduced, which showed that both an effective lubrication and the liquid exchange between the drop and the porous substrates are equally important. Spreading of silicone oils over different nitrocellulose microfiltration membranes was carried out. The experimental laws of the radius of spreading on time confirmed the theory predictions. The spreading of small liquid drops over thin dry porous layers has also been investigated from both theoretical and experimental points of view. The drop motion over a dry porous layer appears caused by the interplay of two processes: (a). the spreading of the drop over already saturated parts of the porous layer, which results in a growth of the drop base, and (b). the imbibition of the liquid from the drop into the porous substrate, which results in a shrinkage of the drop base and a growth of the wetted region inside the porous layer. As a result of these two competing processes the radius of the drop base goes through a maximum as time proceeds. A system of two differential equations has been derived to describe the time evolution of the radii of both the drop base and the wetted region inside the porous layer. This system includes two parameters, one accounts for the effective lubrication coefficient of the liquid over the wetted porous substrate, and

  16. Interfacial biocatalysis on charged and immobilized substrates: the roles of enzyme and substrate surface charge.

    PubMed

    Feller, Bob E; Kellis, James T; Cascão-Pereira, Luis G; Robertson, Channing R; Frank, Curtis W

    2011-01-04

    An enzyme charge ladder was used to examine the role of electrostatic interactions involved in biocatalysis at the solid-liquid interface. The reactive substrate consisted of an immobilized bovine serum albumin (BSA) multilayer prepared using a layer-by-layer technique. The zeta potential of the BSA substrate and each enzyme variant was measured to determine the absolute charge in solution. Enzyme adsorption and the rate of substrate surface hydrolysis were monitored for the enzyme charge ladder series to provide information regarding the strength of the enzyme-substrate interaction and the rate of interfacial biocatalysis. First, each variant of the charge ladder was examined at pH 8 for various solution ionic strengths. We found that for positively charged variants the adsorption increased with the magnitude of the charge until the surface became saturated. For higher ionic strength solutions, a greater positive enzyme charge was required to induce adsorption. Interestingly, the maximum catalytic rate was not achieved at enzyme saturation but at an invariable intermediate level of adsorption for each ionic strength value. Furthermore, the maximum achievable reaction rate for the charge ladder was larger for higher ionic strength values. We propose that diffusion plays an important role in interfacial biocatalysis, and for strong enzyme-substrate interaction, the rate of diffusion is reduced, leading to a decrease in the overall reaction rate. We investigated the effect of substrate charge by varying the solution pH from 6.1 to 8.7 and by examining multiple ionic strength values for each pH. The same intermediate level of adsorption was found to maximize the overall reaction rate. However, the ionic strength response of the maximum achievable rate was clearly dependent on the pH of the experiment. We propose that this observation is not a direct effect of pH but is caused by the change in substrate surface charge induced by changing the pH. To prove this

  17. Influence of substrate modulus on gecko adhesion

    NASA Astrophysics Data System (ADS)

    Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2017-03-01

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).

  18. Influence of substrate modulus on gecko adhesion

    PubMed Central

    Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2017-01-01

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics). PMID:28287647

  19. Analysis of microstrip antennas using magnetic substrates

    NASA Astrophysics Data System (ADS)

    Vakati, Venkata Jagadish Prasad

    The substrate materials play a major role in the design, production and, most importantly, the performance of the Microstrip antennas. The main goal of this thesis lies in performing a comprehensive and exhaustive study as well as an analysis of how magnetic substrates affect the performance indices of the Microstrip antennas. This project takes into consideration the fact that study of magnetic materials as substrates is a relatively uncharted territory and that a few studies into this field have shown many potential facts. This project narrows the antenna under study to a rectangular Microstrip antenna, due to both the simplicity and the versatility of this structure and the scalability of the study. The project was performed using simulation of Microstrip antenna in CST Microwave Studio with magnetic substrates, over a range of mur, and recording the performance indices of the antenna. The performance indices that were considered for the study were Directivity, Efficiency, Gain, Bandwidth, Resonant frequency and VSWR. The method followed in this study can be easily scaled further to accommodate more performance indices, if needed. The observations were later used to draw practical inferences. Also as an extension, wide band 2x2 Microstrip antenna is designed with an additional degree of freedom where changing the feed distance can cover different bands in GSM frequency.

  20. Do cellulose binding domains increase substrate accessibility?

    PubMed

    Esteghlalian, A R; Srivastava, V; Gilkes, N R; Kilburn, D G; Warren, R A; Saddle, J N

    2001-01-01

    This article provides an overview of various theories proposed during the past five decades to describe the enzymatic hydrolysis of cellulose highlighting the major shifts that these theories have undergone. It also describes the effect of the cellulose-binding domain (CBD) of an exoglucanase/xylanase from bacterium Cellulomonas fimi on the enzymatic hydrolysis of Avicel. Pretreatment of Avicel with CBDCex at 4 and 37 degrees C as well as simultaneous addition of CBDCex to the hydrolytic enzyme (Celluclast, Novo, Nordisk) reduced the initial rate of hydrolysis owing to irreversible binding of CBD proteins to the substrate's binding sites. Nonetheless, near complete hydrolysis was achieved even in the presence of CBDCex. Protease treatment of both pure and CBDCex-treated Avicel reduced the substrates' hydrolyzability, perhaps owing to proteolysis of the hydrolyzing enzyme (Celluclast) by the residual Proteinase K remaining in the substrate. Better protocols for complete removal of CBD proteins from the substrate need to be developed to investigate the effect of CBD adsorption on cellulose digestibility.

  1. Enzyme Substrate Reactions in High Magnetic Fields

    PubMed Central

    Maling, J. E.; Weissbluth, M.; Jacobs, E. E.

    1965-01-01

    The reaction rates of two enzyme substrate systems, ribonuclease-RNA and succinate-cytochrome c reductase, were followed as a function of magnetic field from zero to 48,000 gauss. The reaction rates remained constant to within 10 per cent. PMID:5884011

  2. Instabilities of soft films on compliant substrates

    NASA Astrophysics Data System (ADS)

    Holland, M. A.; Li, B.; Feng, X. Q.; Kuhl, E.

    2017-01-01

    Instabilities in bilayered systems can generate a wide variety of patterns ranging from simple folds, wrinkles, and creases to complex checkerboards, hexagons, and herringbones. Physics-based theories traditionally model these systems as a thin film on a thick substrate under confined compression and assume that the film is orders of magnitude stiffer than the substrate. However, instability phenomena in soft films on soft substrates remain insufficiently understood. Here we show that soft bilayered systems are highly sensitive to the stiffness ratio, boundary conditions, and mode of compression. In a systematic analysis over a wide range of stiffness ratios, from 0.1 < β < 1000 , for eight different compression modes including whole-domain compression, substrate prestretch, and film growth, we observe significantly different instability characteristics in the low-stiffness-contrast regime, for β < 10 . While systems with inverse stiffness ratios under whole-domain compression are unstable for a wide range of wrinkling modes, under film-only compression, the same systems display distinct wrinkling modes.Strikingly, these discrepancies disappear when using measures of effective strain, effective stiffness, and effective wavelength. Our study suggests that future instability studies should use these effective measures to standardize their findings. Our results have important applications in soft matter and living matter physics, where stiffness contrasts are low and small environmental changes can have large effects on morphogenesis, pattern tabselection, and the evolution of shape.

  3. Influence of substrate modulus on gecko adhesion.

    PubMed

    Klittich, Mena R; Wilson, Michael C; Bernard, Craig; Rodrigo, Rochelle M; Keith, Austin J; Niewiarowski, Peter H; Dhinojwala, Ali

    2017-03-13

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system's performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).

  4. Buckling Behavior of Substrate Supported Graphene Sheets

    PubMed Central

    Yang, Kuijian; Chen, Yuli; Pan, Fei; Wang, Shengtao; Ma, Yong; Liu, Qijun

    2016-01-01

    The buckling of graphene sheets on substrates can significantly degrade their performance in materials and devices. Therefore, a systematic investigation on the buckling behavior of monolayer graphene sheet/substrate systems is carried out in this paper by both molecular mechanics simulations and theoretical analysis. From 70 simulation cases of simple-supported graphene sheets with different sizes under uniaxial compression, two different buckling modes are investigated and revealed to be dominated by the graphene size. Especially, for graphene sheets with length larger than 3 nm and width larger than 1.1 nm, the buckling mode depends only on the length/width ratio. Besides, it is revealed that the existence of graphene substrate can increase the critical buckling stress and strain to 4.39 N/m and 1.58%, respectively, which are about 10 times those for free-standing graphene sheets. Moreover, for graphene sheets with common size (longer than 20 nm), both theoretical and simulation results show that the critical buckling stress and strain are dominated only by the adhesive interactions with substrate and independent of the graphene size. Results in this work provide valuable insight and guidelines for the design and application of graphene-derived materials and nano-electromechanical systems. PMID:28787831

  5. The Invisible Substrate of Information Science.

    ERIC Educational Resources Information Center

    Bates, Marcia J.

    1999-01-01

    Articulates key elements in the "invisible substrate" of information science. Emphasizes information science's role as a meta-science--conducting research and developing theory around documentary products of other disciplines and activities. Suggests that mental activities of information science center around "representation" and "organization" of…

  6. Spatially Selective Graphene Formation on Si Substrate

    NASA Astrophysics Data System (ADS)

    Yue, Naili; Zhang, Yong; Tsu, Raphael

    2012-02-01

    A uniform large area graphene is useful for applications such as electrode in a touch screen or substrate for growing another material. For applications where graphene is used either as active material (FET for instance) or electrode in a 2-D device array, to form a 2D (electronic) superlattice or photonic crystal, it is critically important to be able to form graphene at selective locations, in desirable size and shape on a substrate, without relying on mechanical cutting. It would be even more significant if the substrate is a Si wafer for coupling with the mature microelectronic technology. We have developed a technique that can achieve these goals. A thin SiC film is first deposited on a Si substrate using MBE. Then, at ambient condition, a focused laser beam is used to convert SiC to graphene at the selected location with the shape and size that can be defined by either a lithographic method or simply by a focused laser beam. The graphene conversion has been verified by structural characterization (TEM, SEM/EDS, etc.) and Raman spectroscopy.

  7. Rectangular microstrip antenna on a ferrite substrate

    NASA Astrophysics Data System (ADS)

    Das, S.; Chowdhury, S. K.

    1982-05-01

    The bandwidth and radiation characteristics of a simple quarter wave microstrip antenna on a typical ferrite substrate are measured and compared with the theoretical results in the lower range of ultrahigh frequency (UHF). A method has also been discussed for impedance matching of the antenna to the feed line.

  8. Hertzian Dipole Radiation over Isotropic Magnetodielectric Substrates

    DTIC Science & Technology

    2015-03-01

    public release; distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This report investigates dipole antennas printed on grounded...engineering of thin planar antennas . Since these materials often require complicated constitutive equations to describe their properties rigorously, the...material properties and substrate thickness. 15. SUBJECT TERMS Magnetodielectrics, planar antennas , boundary value problems, contour integration, branch

  9. Correlation of Cell and Substrate Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Setton, Tedhar; Levine, Joshua; Levine, Joseph; Guan, E.; Collazo, Lourdes; Ge, Shouren; Entcheva, Emilia; Rafailovich, Miriam

    2003-03-01

    The mechanical properties of neonatal rat ventricular fibroblasts plated onto elastomer surfaces were studied in vitro and correlated to the mechanical response of the substrate. In order to differentiate the response of the cells to mechanical as opposed to mechanical modifications in their environment, only the rheological properties of the substrates were modified. In the case of entangled polymers this can be accomplished either by varying the molecular weight or the thickness of polymer films spun cast onto rigid supports. Scanning lateral force microscopy, which has been shown to be an effective technique for measuring relative modulii of surfaces(1) was used to track the mechanical response of the substrates as a function of processing procedures, molecular weight, both in liquid, air, and following fibronectin incubation. The response of the living cells was then compared to that of the underlying substrate. The samples were then stained and the distribution of actin correlated to the mechanical response. 1. S. Ge et al. Phys. Rev. Lett. 11, (2000)2340

  10. Substrate reduction therapy for glycosphingolipid storage disorders.

    PubMed

    Lachmann, R H; Platt, F M

    2001-03-01

    Substrate reduction therapy is a novel approach to treating glycosphingolipid (GSL) lysosomal storage disorders. These diseases are caused by mutations in the genes coding for enzymes involved in GSL catabolism and are characterised by the accumulation of GSL substrates within the lysosomes of cells. The aim of substrate reduction therapy is to inhibit the rate of synthesis of GSLs to levels where the residual activity of the mutant catabolic enzyme is sufficient to prevent pathological storage. In this review we discuss the development of N-butyldeoxynojirimycin (NB-DNJ), an imino sugar that inhibits the ceramide-specific glucosyltransferase which catalyses the first committed step of GSL synthesis. This agent has been shown to slow accumulation of stored glycolipid in an in vitro model of Gaucher's disease and in knockout mouse models of Tay-Sachs and Sandhoff diseases. Furthermore, administration of NB-DNJ to Sandhoff mice delays the onset of neurological disease and also slows its progression. We discuss safety and efficacy data from the clinical trial of substrate reduction with NB-DNJ which has been undertaken in patients with Type 1 Gaucher's disease. This trial provides a proof-of-principle for the use of this approach in a wide range of GSL lysosomal storage diseases.

  11. Drosophila as an unconventional substrate for microfabrication

    NASA Astrophysics Data System (ADS)

    Shum, Angela J.; Parviz, Babak A.

    2007-02-01

    We present the application of Drosophila fruit flies as an unconventional substrate for microfabrication. Drosophila by itself represents a complex system capable of many functions not attainable with current microfabrication technology. By using Drosophila as a substrate, we are able to capitalize on these natural functions while incorporating additional functionality into a superior hybrid system. In the following, development of microfabrication processes for Drosophila substrates is discussed. In particular, results of a study on Drosophila tolerance to vacuum pressure during multiple stages of development are given. A remarkable finding that adult Drosophila may withstand up to 3 hours of exposure to vacuum with measurable survival is noted. This finding opens a number of new opportunities for performing fabrication processes, similar to the ones performed on a silicon wafer, on a fruit fly as a live substrate. As a model microfabrication process, it is shown how a collection of Drosophila can be made to self-assemble into an array of microfabricated recesses on a silicon wafer and how a shadow mask can be used to thermally evaporate 100 nm of indium on flies. The procedure resulted in the production of a number of live flies with a pre-designed metal micropattern on their wings. This demonstration of vacuum microfabrication on a live organism provides the first step towards the development of a hybrid biological/solid-state manufacturing process for complex microsystems.

  12. Plasmonic substrates for surface-enhanced spectroscopies

    NASA Astrophysics Data System (ADS)

    Le, F.; Hao, F.; Nordlander, P.

    2006-08-01

    Using the Plasmon Hybridization (PH) method and the Finite-Difference Time-Domain (FDTD) method, we investigate the plasmonic properties of finite metallic nanopartices interacting with extended metallic substrates such as thin films and wires. The results from the two computational methods are found to agree very well. We show that the plasmons of a metallic nanoparticle couple to the delocalized plasmons of extended substrates in the same manner as an electronic impurity level couples to an continuum of electronic states. The interaction can result in both localized plasmons and virtual states in the plasmonic continuum. The virtual states are composed of delocalized plasmons from the extended substrate and depend sensitively on the geometry of the system, the polarization of incident electromagnetic excitations as well as the background dielectric properties of the structures. We demonstrate that the virtual state can provide large electric field enhancements over a broad and tunable spectral regime. Our investigations show that plasmonic structures supporting virtual states are highly suitable as substrates for surface enhanced spectroscopic applications and may be useful in plasmonic waveguiding applications.

  13. Compliant substrate technology for dissimilar epitaxy

    SciTech Connect

    FLORO,JERROLD A.; LEE,STEPHEN R.; FOLLSTAEDT,DAVID M.; KLEM,JOHN F.

    2000-03-01

    Strained-layer semiconductor films offer tremendous potential with regards to optoelectronic applications for high speed communications, mobile communications, sensing, and novel logic devices. It is an unfortunate reality that many of the possible film/substrate combinations that could be exploited technologically are off limits because of large differences in lattice parameters, chemical compatibilities, or thermal expansion rates. These mechanical, chemical, and thermal incompatibilities manifest themselves primarily in terms of lattice defects such as dislocations and antiphase boundaries, and in some cases through enhanced surface roughness. An additional limitation, from a production point of view, is money. Device manufacturers as a rule want the cheapest substrate possible. Freeing the heteroepitaxial world of the bonds of (near) lattice matching would vastly expand the types of working devices that could be grown. As a result, a great deal of effort has been expended finding schemes to integrate dissimilar film/substrate materials while preserving the perfection of the film layer. One such scheme receiving significant attention lately is the so-called compliant substrate approach.

  14. Substrate radical intermediates in soluble methane monooxygenase.

    PubMed

    Liu, Aimin; Jin, Yi; Zhang, Jingyan; Brazeau, Brian J; Lipscomb, John D

    2005-12-09

    EPR spin-trapping experiments were carried out using the three-component soluble methane monooxygenase (MMO). Spin-traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), alpha-4-pyridyl-1-oxide N-tert-butylnitrone (POBN), and nitrosobenzene (NOB) were used to investigate the possible formation of substrate radical intermediates during catalysis. In contrast to a previous report, the NADH-coupled oxidations of various substrates did not produce any trapped radical species when DMPO or POBN was present. However, radicals were detected by these traps when only the MMO reductase component and NADH were present. DMPO and POBN were found to be weak inhibitors of the MMO reaction. In contrast, NOB is a strong inhibitor for the MMO-catalyzed nitrobenzene oxidation reaction. When NOB was used as a spin-trap in the complete MMO system with or without substrate, EPR signals from an NOB radical were detected. We propose that a molecule of NOB acts simultaneously as a substrate and a spin-trap for MMO, yielding the long-lived radical and supporting a stepwise mechanism for MMO.

  15. Drying of Pigment-Cellulose Nanofibril Substrates

    PubMed Central

    Timofeev, Oleg; Torvinen, Katariina; Sievänen, Jenni; Kaljunen, Timo; Kouko, Jarmo; Ketoja, Jukka A.

    2014-01-01

    A new substrate containing cellulose nanofibrils and inorganic pigment particles has been developed for printed electronics applications. The studied composite structure contains 80% fillers and is mechanically stable and flexible. Before drying, the solids content can be as low as 20% due to the high water binding capacity of the cellulose nanofibrils. We have studied several drying methods and their effects on the substrate properties. The aim is to achieve a tight, smooth surface keeping the drying efficiency simultaneously at a high level. The methods studied include: (1) drying on a hot metal surface; (2) air impingement drying; and (3) hot pressing. Somewhat surprisingly, drying rates measured for the pigment-cellulose nanofibril substrates were quite similar to those for the reference board sheets. Very high dewatering rates were observed for the hot pressing at high moisture contents. The drying method had significant effects on the final substrate properties, especially on short-range surface smoothness. The best smoothness was obtained with a combination of impingement and contact drying. The mechanical properties of the sheets were also affected by the drying method and associated temperature. PMID:28788220

  16. Scalable cell alignment on optical media substrates.

    PubMed

    Anene-Nzelu, Chukwuemeka G; Choudhury, Deepak; Li, Huipeng; Fraiszudeen, Azmall; Peh, Kah-Yim; Toh, Yi-Chin; Ng, Sum Huan; Leo, Hwa Liang; Yu, Hanry

    2013-07-01

    Cell alignment by underlying topographical cues has been shown to affect important biological processes such as differentiation and functional maturation in vitro. However, the routine use of cell culture substrates with micro- or nano-topographies, such as grooves, is currently hampered by the high cost and specialized facilities required to produce these substrates. Here we present cost-effective commercially available optical media as substrates for aligning cells in culture. These optical media, including CD-R, DVD-R and optical grating, allow different cell types to attach and grow well on them. The physical dimension of the grooves in these optical media allowed cells to be aligned in confluent cell culture with maximal cell-cell interaction and these cell alignment affect the morphology and differentiation of cardiac (H9C2), skeletal muscle (C2C12) and neuronal (PC12) cell lines. The optical media is amenable to various chemical modifications with fibronectin, laminin and gelatin for culturing different cell types. These low-cost commercially available optical media can serve as scalable substrates for research or drug safety screening applications in industry scales.

  17. Inverter power module with distributed support for direct substrate cooling

    DOEpatents

    Miller, David Harold [San Pedro, CA; Korich, Mark D [Chino Hills, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA

    2012-08-21

    Systems and/or methods are provided for an inverter power module with distributed support for direct substrate cooling. An inverter module comprises a power electronic substrate. A first support frame is adapted to house the power electronic substrate and has a first region adapted to allow direct cooling of the power electronic substrate. A gasket is interposed between the power electronic substrate and the first support frame. The gasket is configured to provide a seal between the first region and the power electronic substrate. A second support frame is adapted to house the power electronic substrate and joined to the first support frame to form the seal.

  18. Kinase-interacting substrate screening is a novel method to identify kinase substrates

    PubMed Central

    Amano, Mutsuki; Hamaguchi, Tomonari; Shohag, Md. Hasanuzzaman; Kozawa, Kei; Kato, Katsuhiro; Zhang, Xinjian; Yura, Yoshimitsu; Matsuura, Yoshiharu; Kataoka, Chikako; Nishioka, Tomoki

    2015-01-01

    Protein kinases play pivotal roles in numerous cellular functions; however, the specific substrates of each protein kinase have not been fully elucidated. We have developed a novel method called kinase-interacting substrate screening (KISS). Using this method, 356 phosphorylation sites of 140 proteins were identified as candidate substrates for Rho-associated kinase (Rho-kinase/ROCK2), including known substrates. The KISS method was also applied to additional kinases, including PKA, MAPK1, CDK5, CaMK1, PAK7, PKN, LYN, and FYN, and a lot of candidate substrates and their phosphorylation sites were determined, most of which have not been reported previously. Among the candidate substrates for Rho-kinase, several functional clusters were identified, including the polarity-associated proteins, such as Scrib. We found that Scrib plays a crucial role in the regulation of subcellular contractility by assembling into a ternary complex with Rho-kinase and Shroom2 in a phosphorylation-dependent manner. We propose that the KISS method is a comprehensive and useful substrate screen for various kinases. PMID:26101221

  19. Substrate binding and specificity of rhomboid intramembrane protease revealed by substrate-peptide complex structures.

    PubMed

    Zoll, Sebastian; Stanchev, Stancho; Began, Jakub; Skerle, Jan; Lepšík, Martin; Peclinovská, Lucie; Majer, Pavel; Strisovsky, Kvido

    2014-10-16

    The mechanisms of intramembrane proteases are incompletely understood due to the lack of structural data on substrate complexes. To gain insight into substrate binding by rhomboid proteases, we have synthesised a series of novel peptidyl-chloromethylketone (CMK) inhibitors and analysed their interactions with Escherichia coli rhomboid GlpG enzymologically and structurally. We show that peptidyl-CMKs derived from the natural rhomboid substrate TatA from bacterium Providencia stuartii bind GlpG in a substrate-like manner, and their co-crystal structures with GlpG reveal the S1 to S4 subsites of the protease. The S1 subsite is prominent and merges into the 'water retention site', suggesting intimate interplay between substrate binding, specificity and catalysis. Unexpectedly, the S4 subsite is plastically formed by residues of the L1 loop, an important but hitherto enigmatic feature of the rhomboid fold. We propose that the homologous region of members of the wider rhomboid-like protein superfamily may have similar substrate or client-protein binding function. Finally, using molecular dynamics, we generate a model of the Michaelis complex of the substrate bound in the active site of GlpG.

  20. Substrate limitation for methanogenesis in hypersaline environments.

    PubMed

    Kelley, Cheryl A; Poole, Jennifer A; Tazaz, Amanda M; Chanton, Jeffrey P; Bebout, Brad M

    2012-02-01

    Motivated by the increasingly abundant evidence for hypersaline environments on Mars and reports of methane in its atmosphere, we examined methanogenesis in hypersaline ponds in Baja California Sur, Mexico, and in northern California, USA. Methane-rich bubbles trapped within or below gypsum/halite crusts have δ¹³C values near -40‰. Methane with these relatively high isotopic values would typically be considered thermogenic; however, incubations of crust samples resulted in the biological production of methane with similar isotopic composition. A series of measurements aimed at understanding the isotopic composition of methane in hypersaline systems was therefore undertaken. Methane production rates, as well as the concentrations and isotopic composition of the particulate organic carbon (POC), were measured. Methane production was highest from microbial communities living within gypsum crusts, whereas POC content at gypsum/halite sites was low, generally less than 1% of the total mass. The isotopic composition of the POC ranged from -26‰ to -10‰. To determine the substrates used by the methanogens, ¹³C-labeled methylamines, methanol, acetate, and bicarbonate were added to individual incubation vials, and the methane produced was monitored for ¹³C content. The main substrates used by the methanogens were the noncompetitive substrates, the methylamines, and methanol. When unlabeled trimethylamine (TMA) was added to incubating gypsum/halite crusts in increasing concentrations, the isotopic composition of the methane produced became progressively lower; the lowest methane δ¹³C values occurred when the most TMA was added (1000 μM final concentration). This decrease in the isotopic composition of the methane produced with increasing TMA concentrations, along with the high in situ methane δ¹³C values, suggests that the methanogens within the crusts are operating at low substrate concentrations. It appears that substrate limitation is decreasing

  1. Silvering substrates after CO2 snow cleaning

    NASA Astrophysics Data System (ADS)

    Zito, Richard R.

    2005-09-01

    There have been some questions in the astronomical community concerning the quality of silver coatings deposited on substrates that have been cleaned with carbon dioxide snow. These questions center around the possible existence of carbonate ions left behind on the substrate by CO2. Such carbonate ions could react with deposited silver to produce insoluble silver carbonate, thereby reducing film adhesion and reflectivity. Carbonate ions could be produced from CO2 via the following mechanism. First, during CO2 snow cleaning, a small amount of moisture can condense on a surface. This is especially true if the jet of CO2 is allowed to dwell on one spot. CO2 gas can dissolve in this moisture, producing carbonic acid, which can undergo two acid dissociations to form carbonate ions. In reality, it is highly unlikely that charged carbonate ions will remain stable on a substrate for very long. As condensed water evaporates, Le Chatelier's principle will shift the equilibrium of the chain of reactions that produced carbonate back to CO2 gas. Furthermore, the hydration of CO2 reaction of CO2 with H20) is an extremely slow process, and the total dehydrogenation of carbonic acid is not favored. Living tissues that must carry out the equilibration of carbonic acid and CO2 use the enzyme carbonic anhydrase to speed up the reaction by a factor of one million. But no such enzymatic action is present on a clean mirror substrate. In short, the worst case analysis presented below shows that the ratio of silver atoms to carbonate radicals must be at least 500 million to one. The results of chemical tests presented here support this view. Furthermore, film lift-off tests, also presented in this report, show that silver film adhesion to fused silica substrates is actually enhanced by CO2 snow cleaning.

  2. Soil pore structure and substrate C mineralization

    NASA Astrophysics Data System (ADS)

    Sleutel, Steven; Maenhout, Peter; Vanhoorebeke, Luc; Cnudde, Veerle; De Neve, Stefaan

    2014-05-01

    Our aim was to investigate the complex interactions between soil pore structure, soil biota and decomposition of added OM substrates. We report on a lab incubation experiment in which CO2 respiration from soil cores was monitored (headspace GC analysis) and an X-ray CT approach yielded soil pore size distributions. Such combined use of X-ray CT with soil incubation studies was obstructed, until now, by many practical constraints such as CT-volume quality, limited resolution, scanning time and complex soil pore network quantification, which have largely been overcome in this study. We incubated a sandy loam soil (with application of ground grass or sawdust) in 18 small aluminium rings (Ø 1 cm, h 1 cm). Bulk density was adjusted to 1.1 or 1.3 Mg m-3 (compaction) and 6 rings were filled at a coarser Coarse Sand:Fine Sand:Silt+Clay ratio. While compaction induced a strong reduction in the cumulative C mineralization for both grass and sawdust substrates, artificial change to a coarser soil texture only reduced net C mineralization from the added sawdust. There thus appears to be a strong interaction effect between soil pore structure and substrate type on substrate decomposition. Correlation coefficients between the C mineralization rates and volumes of 7 pore size classes (from the X-ray CT data) also showed an increasing positive correlation with increasing pore size. Since any particulate organic matter initially present in the soil was removed prior to the experiment (sieving, ashing the >53µm fraction and recombining with the <53µm fraction), the added OM can be localized by means of X-ray CT. Through on-going image analysis the surrounding porosity of the added grass or sawdust particles is being quantified to further study the interaction between the soil pore structure and substrate decomposition.

  3. Graphene growth on coinage-metal substrates

    NASA Astrophysics Data System (ADS)

    McCarty, Kevin

    2012-02-01

    The low solubility of carbon in Cu and Au gives these coinage metals advantages as substrates for graphene growth. Namely, growth occurs exclusively by surface processes, avoiding the complications of C segregating from the bulk of the metal substrate. However, the relatively weak interactions of Cu and Au with graphene can lead to mosaic films having large ranges of in-plane orientations. This talk will emphasize understanding the relationship between the microstructure of graphene sheets and the mechanisms of island nucleation and growth. We use low-energy electron microscopy (LEEM) to observe growth. We find that bunches of substrate steps on Cu(111) can generate misorientation boundaries in a graphene sheet as it overgrows the steps [1]. Thus, growth on rough Cu(111) leads to large rotational disorder. Optimized growth on smooth Cu(111) and Au(111), however, produces islands all in close registry to a single in-plane orientation. On Cu(100), the most abundant grain orientation of commercial Cu foils, graphene islands align around two equivalent in-plane Cu directions [2]. This inherent source of disorder from symmetry mismatch is further compounded by large spreads of orientation around the equivalent directions. The substrate choice also affects the microscopic growth mechanism. The rate that C diffuses to the graphene islands limits growth on Cu(111) [and likely on Au(111)]. The sheet edges are then morphologically unstable, with dendritic islands at low temperature and six-fold loped islands at higher temperature. In contrast, growth on Cu(100) is limited by the rate of C attaching to the graphene edge. This mechanism, combined with the symmetry mismatch, produces two-fold islands. Finally, the coinage metals will be compared to other transition metal substrates. [4pt] [1] Phys. Rev. B 84, p. 155425 (2011). [0pt] [2] Nano Lett. 10, p. 4890 (2010).

  4. Substrate Stiffness Affects Human Keratinocyte Colony Formation

    PubMed Central

    Zarkoob, Hoda; Bodduluri, Sandeep; Ponnaluri, Sailahari V.; Selby, John C.; Sander, Edward A.

    2015-01-01

    Restoration of epidermal organization and function in response to a variety of pathophysiological insults is critically dependent on coordinated keratinocyte migration, proliferation, and stratification during the process of wound healing. These processes are mediated by the reconfiguration of both cell-cell (desmosomes, adherens junctions) and cell-matrix (focal adhesions, hemidesmosomes) junctions and the cytoskeletal filament networks that they serve to interconnect. In this study, we investigated the role of substrate elasticity (stiffness) on keratinocyte colony formation in vitro during the process of nascent epithelial sheet formation as triggered by the calcium switch model of keratinocyte culture. Keratinocytes cultured on pepsin digested type I collagen coated soft (nominal E = 1.2 kPa) polyacrylamide gels embedded with fluorescent microspheres exhibited (i) smaller spread contact areas, (ii) increased migration velocities, and (iii) increased rates of colony formation with more cells per colony than did keratinocytes cultured on stiff (nominal E = 24 kPa) polyacrylamide gels. As assessed by tracking of embedded microsphere displacements, keratinocytes cultured on soft substrates generated large local substrate deformations that appeared to recruit adjacent keratinocytes into joining an evolving colony. Together with the observed differences in keratinocyte kinematics and substrate deformations, we developed two ad hoc analyses, termed distance rank (DR) and radius of cooperativity (RC), that help to objectively ascribe what we perceive as increasingly cooperative behavior of keratinocytes cultured on soft versus stiff gels during the process of colony formation. We hypothesize that the differences in keratinocyte colony formation observed in our experiments could be due to cell-cell mechanical signaling generated via local substrate deformations that appear to be correlated with the increased expression of β4 integrin within keratinocytes positioned

  5. Unmasking tandem site interaction in human acetylcholinesterase. Substrate activation with a cationic acetanilide substrate.

    PubMed

    Johnson, Joseph L; Cusack, Bernadette; Davies, Matthew P; Fauq, Abdul; Rosenberry, Terrone L

    2003-05-13

    Acetylcholinesterase (AChE) contains a narrow and deep active site gorge with two sites of ligand binding, an acylation site (or A-site) at the base of the gorge, and a peripheral site (or P-site) near the gorge entrance. The P-site contributes to catalytic efficiency by transiently binding substrates on their way to the acylation site, where a short-lived acyl enzyme intermediate is produced. A conformational interaction between the A- and P-sites has recently been found to modulate ligand affinities. We now demonstrate that this interaction is of functional importance by showing that the acetylation rate constant of a substrate bound to the A-site is increased by a factor a when a second molecule of substrate binds to the P-site. This demonstration became feasible through the introduction of a new acetanilide substrate analogue of acetylcholine, 3-(acetamido)-N,N,N-trimethylanilinium (ATMA), for which a = 4. This substrate has a low acetylation rate constant and equilibrates with the catalytic site, allowing a tractable algebraic solution to the rate equation for substrate hydrolysis. ATMA affinities for the A- and P-sites deduced from the kinetic analysis were confirmed by fluorescence titration with thioflavin T as a reporter ligand. Values of a >1 give rise to a hydrolysis profile called substrate activation, and the AChE site-specific mutant W86F, and to a lesser extent wild-type human AChE itself, showed substrate activation with acetylthiocholine as the substrate. Substrate activation was incorporated into a previous catalytic scheme for AChE in which a bound P-site ligand can also block product dissociation from the A-site, and two additional features of the AChE catalytic pathway were revealed. First, the ability of a bound P-site ligand to increase the substrate acetylation rate constant varied with the structure of the ligand: thioflavin T accelerated ATMA acetylation by a factor a(2) of 1.3, while propidium failed to accelerate. Second, catalytic rate

  6. Multifunctional epitaxial systems on silicon substrates

    NASA Astrophysics Data System (ADS)

    Singamaneni, Srinivasa Rao; Prater, John Thomas; Narayan, Jagdish

    2016-09-01

    Multifunctional heterostructures can exhibit a wide range of functional properties, including colossal magneto-resistance, magnetocaloric, and multiferroic behavior, and can display interesting physical phenomena including spin and charge ordering and strong spin-orbit coupling. However, putting this functionality to work remains a challenge. To date, most of the work reported in the literature has dealt with heterostructures deposited onto closely lattice matched insulating substrates such as DyScO3, SrTiO3 (STO), or STO buffered Si(100) using concepts of lattice matching epitaxy (LME). However, strain in heterostructures grown by LME is typically not fully relaxed and the layers contain detrimental defects such as threading dislocations that can significantly degrade the physical properties of the films and adversely affect the device characteristics. In addition, most of the substrates are incompatible with existing CMOS-based technology, where Si (100) substrates dominate. This review discusses recent advances in the integration of multifunctional oxide and non-oxide materials onto silicon substrates. An alternative thin film growth approach, called "domain matching epitaxy," is presented which identifies approaches for minimizing lattice strain and unwanted defects in large misfit systems (7%-25% and higher). This approach broadly allows for the integration of multifunctional materials onto silicon substrates, such that sensing, computation, and response functions can be combined to produce next generation "smart" devices. In general, pulsed laser deposition has been used to epitaxially grow these materials, although the concepts developed here can be extended to other deposition techniques, as well. It will be shown that TiN and yttria-stabilized zirconia template layers provide promising platforms for the integration of new functionality into silicon-based computer chips. This review paper reports on a number of thin-film heterostructure systems that span a

  7. Multifunctional epitaxial systems on silicon substrates

    SciTech Connect

    Singamaneni, Srinivasa Rao; Prater, John Thomas; Narayan, Jagdish

    2016-09-15

    Multifunctional heterostructures can exhibit a wide range of functional properties, including colossal magneto-resistance, magnetocaloric, and multiferroic behavior, and can display interesting physical phenomena including spin and charge ordering and strong spin-orbit coupling. However, putting this functionality to work remains a challenge. To date, most of the work reported in the literature has dealt with heterostructures deposited onto closely lattice matched insulating substrates such as DyScO{sub 3}, SrTiO{sub 3} (STO), or STO buffered Si(100) using concepts of lattice matching epitaxy (LME). However, strain in heterostructures grown by LME is typically not fully relaxed and the layers contain detrimental defects such as threading dislocations that can significantly degrade the physical properties of the films and adversely affect the device characteristics. In addition, most of the substrates are incompatible with existing CMOS-based technology, where Si (100) substrates dominate. This review discusses recent advances in the integration of multifunctional oxide and non-oxide materials onto silicon substrates. An alternative thin film growth approach, called “domain matching epitaxy,” is presented which identifies approaches for minimizing lattice strain and unwanted defects in large misfit systems (7%–25% and higher). This approach broadly allows for the integration of multifunctional materials onto silicon substrates, such that sensing, computation, and response functions can be combined to produce next generation “smart” devices. In general, pulsed laser deposition has been used to epitaxially grow these materials, although the concepts developed here can be extended to other deposition techniques, as well. It will be shown that TiN and yttria-stabilized zirconia template layers provide promising platforms for the integration of new functionality into silicon-based computer chips. This review paper reports on a number of thin

  8. Self-Assembled Local Artificial Substrates of GaAs on Si Substrate

    PubMed Central

    2010-01-01

    We propose a self-assembling procedure for the fabrication of GaAs islands by Droplet Epitaxy on silicon substrate. Controlling substrate temperature and amount of supplied gallium is possible to tune the base size of the islands from 70 up to 250 nm and the density from 107 to 109 cm−2. The islands show a standard deviation of base size distribution below 10% and their shape evolves changing the aspect ratio from 0.3 to 0.5 as size increases. Due to their characteristics, these islands are suitable to be used as local artificial substrates for the integration of III–V quantum nanostructures directly on silicon substrate. PMID:21170400

  9. Use of Dominant-Negative/Substrate Trapping PTP Mutations to Search for PTP Interactors/Substrates.

    PubMed

    Radha, Vegesna

    2016-01-01

    Phosphorylation of proteins on tyrosine residues is the consequence of coordinated action of tyrosine kinases (TKs), and protein tyrosine phosphatases (PTPs). Together, they regulate intermolecular interactions, subcellular localization, and activity of a variety of proteins. The level of total protein-associated tyrosine phosphorylation in eukaryotic cells is only a small fraction of the total phosphorylation. PTPs, which have high specific activity compared to tyrosine kinases, play an important role in maintaining the tyrosine phosphorylation state of proteins and regulate signal transduction pathways and cellular responses. PTPs depend on specific invariant residues that enable binding to substrates phosphorylated at tyrosine and aid catalytic activity. Identification of PTP substrates has helped understand their role in distinct intracellular signaling pathways. Because of their high specific activity, the interaction between tyrosine phosphatases and their substrates is often very transient in the cellular context, and therefore identification of physiological substrates has been difficult. Single-site mutations in the enzymes stabilize interaction between the enzyme and its targets and have been used extensively to identify substrates. The mutations are either of the catalytic cysteine (Cys) residue or other invariant residues and have been classified as substrate-trapping mutants (STMs). These mutants often serve as dominant negatives that can inactivate effector functions of a specific PTP within cells. Considering their association with human disorders, inhibiting specific PTPs is important therapeutically. Since the catalytic domains are largely conserved, developing small-molecule inhibitors to a particular enzyme has proven difficult and therefore alternate strategies to block functions of individual enzymes are seriously being investigated. We provide a description of methods that will be useful to design strategies of using dominant-negative and

  10. Carbon nanotube substrates and catalyzed hot stamp for polishing and patterning the substrates

    DOEpatents

    Wang, Yuhuang [Evanston, IL; Hauge, Robert H [Houston, TX; Schmidt, Howard K [Houston, TX; Kim, Myung Jong [Houston, TX; Kittrell, W Carter [Houston, TX

    2009-09-08

    The present invention is generally directed to catalyzed hot stamp methods for polishing and/or patterning carbon nanotube-containing substrates. In some embodiments, the substrate, as a carbon nanotube fiber end, is brought into contact with a hot stamp (typically at 200-800.degree. C.), and is kept in contact with the hot stamp until the morphology/patterns on the hot stamp have been transferred to the substrate. In some embodiments, the hot stamp is made of material comprising one or more transition metals (Fe, Ni, Co, Pt, Ag, Au, etc.), which can catalyze the etching reaction of carbon with H.sub.2, CO.sub.2, H.sub.2O, and/or O.sub.2. Such methods can (1) polish the carbon nanotube-containing substrate with a microscopically smooth finish, and/or (2) transfer pre-defined patterns from the hot stamp to the substrate. Such polished or patterned carbon nanotube substrates can find application as carbon nanotube electrodes, field emitters, and field emitter arrays for displays and electron sources.

  11. Generation of Micropatterned Substrates Using Micro Photopatterning

    PubMed Central

    Doyle, Andrew D.

    2010-01-01

    Micro photopatterning (µPP) has been developed to rapidly test and generate different patterns for extracellular matrix adsorption without being hindered with the process of making physical stamps through nanolithography techniques. It uses two-photon excitation guided through a point-scanning confocal microscope to locally photoablate poly(vinyl) alcohol (PVA) thin films in user-defined computer-controlled patterns. PVA thin films are ideal for surface blocking, being hydrophilic substrates that deter protein adsorption and cell attachment. Because gold substrates are not used during µPP, all live-cell fluorescent imaging techniques including total internal reflection fluorescence microscopy of GFP–linked proteins can be performed with minimal loss of fluorescence signal. Furthermore, because µPP does not require physical stamps for pattern generation, multiple ECMs or other proteins can be localized within microns of each other. This unit details the setup of µPP as well as giving troubleshooting techniques. PMID:20013752

  12. Alkoxysilane adsorption on metal oxide substrates

    NASA Technical Reports Server (NTRS)

    Ramsier, R. D.; Zhuang, G. R.; Henriksen, P. N.

    1989-01-01

    Reflection-absorption infrared and inelastic electron tunneling spectroscopies have been used to study adsorption of liquid phase mono-, di-, and trialkoxysilanes on evaporated Al and Cu substrates. Spectral evidence shows that substrate properties influence the chemical and physical nature of trialkoxysilane films and that silane functionality plays a role in molecular orientation. Results show that dialkoxysilane films contain structural gradients, with adsorption at the monomolecular level influenced by surface morphology, and with organofunctionality and dosing procedure affecting the formation of thicker films. Evidence is presented that monoalkoxysilanes react with alumina surfaces, and a broad, multipeaked band from 1600 to 1900/cm has been interpreted as characteristic of the silylated AlO(x)Pb interface.

  13. Microorganisms detection on substrates using QCL spectroscopy

    NASA Astrophysics Data System (ADS)

    Padilla-Jiménez, Amira C.; Ortiz-Rivera, William; Castro-Suarez, John R.; Ríos-Velázquez, Carlos; Vázquez-Ayala, Iris; Hernández-Rivera, Samuel P.

    2013-05-01

    Recent investigations have focused on the improvement of rapid and accurate methods to develop spectroscopic markers of compounds constituting microorganisms that are considered biological threats. Quantum cascade lasers (QCL) systems have revolutionized many areas of research and development in defense and security applications, including his area of research. Infrared spectroscopy detection based on QCL was employed to acquire mid infrared (MIR) spectral signatures of Bacillus thuringiensis (Bt), Escherichia coli (Ec) and Staphylococcus epidermidis (Se), which were used as biological agent simulants of biothreats. The experiments were carried out in reflection mode on various substrates such as cardboard, glass, travel baggage, wood and stainless steel. Chemometrics statistical routines such as principal component analysis (PCA) regression and partial least squares-discriminant analysis (PLS-DA) were applied to the recorded MIR spectra. The results show that the infrared vibrational techniques investigated are useful for classification/detection of the target microorganisms on the types of substrates studied.

  14. A cellular glass substrate solar concentrator

    NASA Technical Reports Server (NTRS)

    Bedard, R.; Bell, D.

    1980-01-01

    The design of a second generation point focusing solar concentration is discussed. The design is based on reflective gores fabricated of thin glass mirror bonded continuously to a contoured substrate of cellular glass. The concentrator aperture and structural stiffness was optimized for minimum concentrator cost given the performance requirement of delivering 56 kWth to a 22 cm diameter receiver aperture with a direct normal insolation of 845 watts sq m and an operating wind of 50 kmph. The reflective panel, support structure, drives, foundation and instrumentation and control subsystem designs, optimized for minimum cost, are summarized. The use of cellular glass as a reflective panel substrate material is shown to offer significant weight and cost advantages compared to existing technology materials.

  15. Standard method for characterizing SERS substrates

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason A.; Hankus, Mikella E.; Christesen, Steven D.; Fountain, Augustus W., III; Pellegrino, Paul M.; Emmons, Erik D.; Tripathi, Ashish; Wilcox, Phillip; Emge, Darren

    2012-06-01

    We present the methodology and results of a standard assessment protocol to evaluate disparate SERS substrates that were developed for the Defense Advanced Research Programs Agency (DARPA) SERS Science and Technology Fundamentals Program. The results presented are a snapshot of a collaborative effort between the US Army Edgewood Chemical Biological Center, and the US Army Research Laboratory-Aldelphi Laboratory Center to develop a quantitative analytical method with spectroscopic figures of merit to unambiguously compare the sensitivity and reproducibility of various SERS substrates submitted by the program participants. We present the design of a common assessment protocol and the definition of a SERS enhancement value (SEV) in order to effectively compare SERS active surfaces.

  16. Signal Peptidase Enzymology and Substrate Specificity Profiling.

    PubMed

    Dalbey, R E; Pei, D; Ekici, Ö D

    2017-01-01

    Signal peptidases are membrane proteases that play crucial roles in the protein transport pathway of bacteria. They cleave off the signal peptide from precursor proteins that are membrane inserted by the SecYEG or Tat translocons. Signal peptide cleavage releases the translocated protein from the inner membrane allowing the protein to be exported to the periplasm, outer membrane, or secreted into the medium. Signal peptidases are very important proteins to study. They are unique serine proteases with a Ser-Lys dyad, catalyze cleavage at the membrane surface, and are promising potential antibacterial drug targets. This chapter will focus on the isolation of signal peptidases and the preprotein substrates, as well as describe a peptide library approach for characterizing the substrate specificity.

  17. Vertical-Substrate MPCVD Epitaxial Nanodiamond Growth.

    PubMed

    Tzeng, Yan-Kai; Zhang, Jingyuan Linda; Lu, Haiyu; Ishiwata, Hitoshi; Dahl, Jeremy; Carlson, Robert M K; Yan, Hao; Schreiner, Peter R; Vučković, Jelena; Shen, Zhi-Xun; Melosh, Nicholas; Chu, Steven

    2017-03-08

    Color center-containing nanodiamonds have many applications in quantum technologies and biology. Diamondoids, molecular-sized diamonds have been used as seeds in chemical vapor deposition (CVD) growth. However, optimizing growth conditions to produce high crystal quality nanodiamonds with color centers requires varying growth conditions that often leads to ad-hoc and time-consuming, one-at-a-time testing of reaction conditions. In order to rapidly explore parameter space, we developed a microwave plasma CVD technique using a vertical, rather than horizontally oriented stage-substrate geometry. With this configuration, temperature, plasma density, and atomic hydrogen density vary continuously along the vertical axis of the substrate. This variation allowed rapid identification of growth parameters that yield single crystal diamonds down to 10 nm in size and 75 nm diameter optically active center silicon-vacancy (Si-V) nanoparticles. Furthermore, this method may provide a means of incorporating a wide variety of dopants in nanodiamonds without ion irradiation damage.

  18. Atom chips on direct bonded copper substrates

    SciTech Connect

    Squires, Matthew B.; Stickney, James A.; Carlson, Evan J.; Baker, Paul M.; Buchwald, Walter R.; Wentzell, Sandra; Miller, Steven M.

    2011-02-15

    We present the use of direct bonded copper (DBC) for the straightforward fabrication of high power atom chips. Atom chips using DBC have several benefits: excellent copper/substrate adhesion, high purity, thick (>100 {mu}m) copper layers, high substrate thermal conductivity, high aspect ratio wires, the potential for rapid (<8 h) fabrication, and three-dimensional atom chip structures. Two mask options for DBC atom chip fabrication are presented, as well as two methods for etching wire patterns into the copper layer. A test chip, able to support 100 A of current for 2 s without failing, is used to determine the thermal impedance of the DBC. An assembly using two DBC atom chips is used to magnetically trap laser cooled {sup 87}Rb atoms. The wire aspect ratio that optimizes the magnetic field gradient as a function of power dissipation is determined to be 0.84:1 (height:width).

  19. Enhanced photoacoustic detection using photonic crystal substrate

    SciTech Connect

    Zhao, Yunfei; Liu, Kaiyang; McClelland, John; Lu, Meng

    2014-04-21

    This paper demonstrates the enhanced photoacoustic sensing of surface-bound light absorbing molecules and metal nanoparticles using a one-dimensional photonic crystal (PC) substrate. The PC structure functions as an optical resonator at the wavelength where the analyte absorption is strong. The optical resonance of the PC sensor provides an intensified evanescent field with respect to the excitation light source and results in enhanced optical absorption by surface-immobilized samples. For the analysis of a light absorbing dye deposited on the PC surface, the intensity of photoacoustic signal was enhanced by more than 10-fold in comparison to an un-patterned acrylic substrate. The technique was also applied to detect gold nanorods and exhibited more than 40 times stronger photoacoustic signals. The demonstrated approach represents a potential path towards single molecule absorption spectroscopy with greater performance and inexpensive instrumentation.

  20. Development of Mullite Substrates and Containers

    NASA Technical Reports Server (NTRS)

    Sibold, J. D.

    1979-01-01

    The mullite-molten silicon interaction was evaluated through fabrication of a series of bodies made with variations in density, alumina-silica ratio, and glass-crystalline ratio. The materials were tested in a sessile drop technique. None of the variations stood up to extended exposure to molten silicon sufficiently to be recommended as a container material. However, directional solidification experiments suggest that, under proper conditions, contamination of the silicon by mullite containers can be minimized. To improve an already good thermal expansion match between mullite and silicon, compositional variations were studied. Altering of the alumina-silica ratio was determined to give a continuously varying thermal expansion. A standard mullite composition was selected and substrates 40 x 4 x .040 inches were fabricated. Slotted substrates of various configurations and various compositions were also fabricated.

  1. Anisotropic artificial substrates for microwave applications

    NASA Astrophysics Data System (ADS)

    Shahvarpour, Attieh

    ) with very low-beam squint, which makes it particularly appropriate for applications in wide band point-to-point communication and radar systems. The antenna is constituted of a mushroom type anisotropic magneto-dielectric artificial grounded slab with uniaxially anisotropic permittivity and permeability tensors. A spectral transmission-line model based on Green functions approach is chosen for the analysis of the structure. A rigorous comparison between the isotropic and anisotropic leaky-wave antennas is performed which reveals that as opposed to anisotropic slabs, isotropic slabs show weak performance in leaky-wave antennas. The properties of planar antennas such as low profile, low cost, compatibility with integrated circuits and their conformal nature have made them appropriate antennas for communications systems. In parallel, bandwidth and miniaturization requirements have increased the demand for millimeter-wave wireless systems, such as radar, remote sensors and highspeed local area networks. However, as frequency increases towards millimeter-wave regime, the radiation efficiency of planar antennas becomes an important issue. This is due to the increased electrical thickness of the substrate and therefore increased number of the excited surface modes which carry part of the energy of the system in the substrate without any efficient contribution to radiation. Therefore, these antennas suffer from low radiation efficiency. This has motivated the third contribution of the thesis which is the interpretation and analysis of the radiation efficiency behavior of the planar antennas on electrically thick substrates. A novel substrate dipole approach is introduced for the explanation of the efficiency behavior. This dipole models the substrate and reduces the problem of the horizontal electric source on the substrate to an equivalent dipole radiating in the free-space. In addition, in this work, some efficiency enhancement solutions at the electrical thicknesses where

  2. Substrate Activation by Iron Superoxo Intermediates

    PubMed Central

    van der Donk, Wilfred A.; Krebs, Carsten; Bollinger, J. Martin

    2010-01-01

    A growing number of non-heme-iron oxygenases and oxidases catalyze reactions for which the well-established mechanistic paradigm involving a single C-H-bond cleaving intermediate of the Fe(IV)-oxo (ferryl) type [1] is insufficient to explain the chemistry. It is becoming clear that, in several of these cases, Fe(III)-superoxide complexes formed by simple addition of O2 to the reduced [Fe(II)] cofactor initiate substrate oxidation by abstracting hydrogen [2]. This substrate-oxidizing entry route into high-valent-iron intermediates makes possible an array of complex and elegant oxidation reactions without consumption of valuable reducing equivalents. Examples of this novel mechanistic strategy are discussed with the goal of bringing forth unifying principles. PMID:20951572

  3. Preparation of nickel substrates for coated conductors.

    SciTech Connect

    Truchan, T. G.; Rountree, F. H.; Lanagan, M. T.; McClellan, S. M.; Miller, D. J.; Goretta, K. C.; Tomsic, M.; Foley, R.

    2000-11-01

    Polycrystalline Ni has been used as a substrate for high-current, coated YBa{sub 2}Cu{sub 3}O{sub x} superconductors. For many conductors, Ni is rolled to large deformation and annealed to produce a cube texture. In this study, Ni was rolled to >95% reduction and annealed in 5% H{sub 2}/95% He at 300-1000 C for various times. The resulting substrates were examined by scanning electron microscopy, X-ray and electron diffraction, and surface interferometry. Key determinations for the Ni were extent of in-plane and out-of-plane texture, surface smoothness, and grain size. The extent of texture was approximately independent of annealing temperature and increased slightly with annealing time. Annealing at temperatures >600 C increased surface roughness, primarily due to grain-boundary grooving. Grain growth was fastest at 1000 C and was proportional to time to the 0.1 power.

  4. EUVL mask substrate specifications (wafer-type)

    SciTech Connect

    Tong, W

    1999-07-01

    The Extreme Ultraviolet Lithography (EUVL) program currently is constructing an alpha-class exposure tool known as the Engineering Test Stand (ETS) that will employ 200mm wafer format masks. This report lists and explains the current specifications for the EUVL mask substrates suitable for use on the ETS. The shape and size of the mask are the same as those of a standard 200mm Si wafer. The flatness requirements are driven by the potential image placement distortion caused by the non-telecentric illumination of EUVL. The defect requirements are driven by the printable-defect size and desired yield for mask blank fabrication. Surface roughness can cause both a loss of light throughput and image speckle. The EUVL mask substrate must be made of low-thermal-expansion material because 40% of the light is absorbed by the multilayers and causes some uncorrectable thermal distortion during printing.

  5. Rhombic preordering on a square substrate.

    PubMed

    Neuhaus, T; Marechal, M; Schmiedeberg, M; Löwen, H

    2013-03-15

    A competition of incommensurate symmetries occurs whenever a system is forced to conform to an ordering that is different from the intrinsically preferred structure of the system itself. As a model system of such a competition, we study the rivalry between the triangular ordering of hard disks and the square symmetry induced by a periodic square substrate. By using density functional theory as well as Monte Carlo computer simulations, we determine the full phase behavior for the case of one particle per minimum. We observe a rhombic preordering structure preceding the hexagonal solid as a direct consequence of the competing symmetries. Furthermore, the square-rhombic transition is reentrant with increasing substrate interaction. Our predictions can be verified in experiments of colloids in laser fields.

  6. Optical substrate materials for synchrotron radiation beamlines

    SciTech Connect

    Howells, M.R.; Paquin, R.A.

    1997-06-01

    The authors consider the materials choices available for making optical substrates for synchrotron radiation beam lines. They find that currently the optical surfaces can only be polished to the required finish in fused silica and other glasses, silicon, CVD silicon carbide, electroless nickel and 17-4 PH stainless steel. Substrates must therefore be made of one of these materials or of a metal that can be coated with electroless nickel. In the context of material choices for mirrors they explore the issues of dimensional stability, polishing, bending, cooling, and manufacturing strategy. They conclude that metals are best from an engineering and cost standpoint while the ceramics are best from a polishing standpoint. They then give discussions of specific materials as follows: silicon carbide, silicon, electroless nickel, Glidcop{trademark}, aluminum, precipitation-hardening stainless steel, mild steel, invar and superinvar. Finally they summarize conclusions and propose ideas for further research.

  7. Examination on Substrate Preheating Process in Cold Gas Dynamic Spraying

    NASA Astrophysics Data System (ADS)

    Yin, Shuo; Wang, Xiao-Fang; Li, Wen-Ya; Guo, Xue-Ping

    2011-06-01

    Substrate preheating always takes an important role in particle bonding and formation of the first layer coating in cold gas dynamic spraying (CGDS). In this study, a systemic investigation on substrate preheating process is conducted with Cu, Al, Steel, and Ti substrate by both numerical and experimental methods. The computational fluid dynamic (CFD) approach is adopted to simulate the heat exchange process between gas and solid substrate. The numerical results show that substrate can be significantly preheated by the high-temperature gas, especially by the gas at the near-wall zone behind the bow shock where the temperature is extremely high. Moreover, the comparison between different substrates implies that substrates with smaller thermal conductivity can achieve higher surface temperature and larger temperature gradient which may greatly contribute to the generation of residual stress, such as Ti substrate in this study. For the heat flux, Cu substrate obtains the largest value at the center zone of the substrate surface, followed by Al, Steel, and Ti substrate, but at the outer zone, the heat flux through the Cu substrate surface is smaller than the other three types of substrates. Besides, based on the experimental results, it is found that the substrate surface temperature amounts to the peak value only when the preheating time is sufficiently long.

  8. Thick crystalline films on foreign substrates

    DOEpatents

    Smith, Henry I.; Atwater, Harry A.; Geis, Michael W.

    1986-01-01

    To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 .mu.m) film on a foreign substrate, the film is formed so as to be thin (<1 .mu.m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns.

  9. Natural cellulose fiber as substrate for supercapacitor.

    PubMed

    Gui, Zhe; Zhu, Hongli; Gillette, Eleanor; Han, Xiaogang; Rubloff, Gary W; Hu, Liangbing; Lee, Sang Bok

    2013-07-23

    Cellulose fibers with porous structure and electrolyte absorption properties are considered to be a good potential substrate for the deposition of energy material for energy storage devices. Unlike traditional substrates, such as gold or stainless steel, paper prepared from cellulose fibers in this study not only functions as a substrate with large surface area but also acts as an interior electrolyte reservoir, where electrolyte can be absorbed much in the cellulose fibers and is ready to diffuse into an energy storage material. We demonstrated the value of this internal electrolyte reservoir by comparing a series of hierarchical hybrid supercapacitor electrodes based on homemade cellulose paper or polyester textile integrated with carbon nanotubes (CNTs) by simple solution dip and electrodeposited with MnO2. Atomic layer deposition of Al2O3 onto the fiber surface was used to limit electrolyte absorption into the fibers for comparison. Configurations designed with different numbers of ion diffusion pathways were compared to show that cellulose fibers in paper can act as a good interior electrolyte reservoir and provide an effective pathway for ion transport facilitation. Further optimization using an additional CNT coating resulted in an electrode of paper/CNTs/MnO2/CNTs, which has dual ion diffusion and electron transfer pathways and demonstrated superior supercapacitive performance. This paper highlights the merits of the mesoporous cellulose fibers as substrates for supercapacitor electrodes, in which the water-swelling effect of the cellulose fibers can absorb electrolyte, and the mesoporous internal structure of the fibers can provide channels for ions to diffuse to the electrochemical energy storage materials.

  10. Rhamnolipid surfactants: alternative substrates, new strategies.

    PubMed

    Benincasa, Maria; Marqués, AnaM; Pinazo, Aurora; Manresa, Angels

    2010-01-01

    This chapter concentrates on the various possibilities of using alternative substrates and new strategies. Such strategies include an integrated production system to reduce the environmental impact and an attempt to minimize residues, which reinforces socio-economic and region-structural development. Additionally, we offer an overview of the physicochemical and biological properties of rhamnolipid surfactants associated with the applications of these molecules in different circumstances.

  11. Microsphere coated substrate containing reactive aldehyde groups

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1984-01-01

    A synthetic organic resin is coated with a continuous layer of contiguous, tangential, individual microspheres having a uniform diameter preferably between 100 Angstroms and 2000 Angstroms. The microspheres are an addition polymerized polymer of an unsaturated aldehyde containing 4 to 20 carbon atoms and are covalently bonded to the substrate by means of high energy radiation grafting. The microspheres contain reactive aldehyde groups and can form conjugates with proteins such as enzymes or other aldehyde reactive materials.

  12. Thick crystalline films on foreign substrates

    DOEpatents

    Smith, H.I.; Atwater, H.A.; Geis, M.W.

    1986-03-18

    To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 [mu]m) film on a foreign substrate, the film is formed so as to be thin (<1 [mu]m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns. 2 figs.

  13. Hydrogenation of biomass-derived substrates

    DOEpatents

    Gordon, John C.; Waidmann, Christopher R.

    2016-06-07

    The .alpha.,.beta.-unsaturated ketone moiety of a substrate representative of non-food based biomass was hydrogenated to the corresponding saturated alcohol moiety using a composition including (1) a copper salt; (2) a phosphine; (3) a polar aprotic solvent such as acetonitrile, and (4) a compound suitable for providing hydrogen for the hydrogenation, such as a suitable silane material or a suitable siloxane material.

  14. Preparation of the Superconductor Substrate: Strontium Titanate

    DTIC Science & Technology

    1988-09-01

    single crystals of strontium titanate is derived from the original method developed by Verneuil . 16 The general procedure for the growth of single... crystals growth are reported. The growth direction was determined to be 5 degrees away from the [2111 direction. ICP-emission spectroscopy irdicates... Growth of Strontium Titanate Crystals 5 2.4 Preparation of Substrates 8 3. RESULTS AND CONCLUSIONS 8 REFERENCES 13 Illustrations 1. Schematic Diagram

  15. Purity of targets prepared on Cu substrates

    NASA Astrophysics Data System (ADS)

    Méens, A.; Rossini, I.; Sens, J. C.

    1993-09-01

    The purity of several elemental self-supporting targets usually prepared by evaporation onto soluble Cu substrates has been studied. The targets were analysed by Rutherford backscattering and instrumental neutron activation analysis. Because of the high percentage of Cu observed in some Si targets, further measurements, including transmission electron microscopy, have been performed on Si targets deposited by e-gun bombardment onto Cu and ion-beam sputtering onto betaine.

  16. Adhesive Electroless Metallization of Fluoropolymeric Substrates

    NASA Astrophysics Data System (ADS)

    Vargo, Terrence G.; Gardella, Joseph A., Jr.; Calvert, Jeffrey M.; Chen, Mu-San

    1993-12-01

    A process for producing patterned metal deposits on fluoropolymeric substrates is described. A metal ion-chelating organosilane is chemisorbed by self-assembly onto a fluoropolymer surface after radio-frequency glow discharge plasma surface hydroxylation. Positional modulation of the surface hydrophobicity is illustrated by wetting. The silane covalently binds an aqueous palladium catalyst and subsequent electroless deposition yields homogeneous or patterned metal deposits that exhibit excellent adhesion to the fluoropolymer.

  17. Hydrazones as substrates for cycloaddition reactions

    NASA Astrophysics Data System (ADS)

    Belskaya, N. P.; Eliseeva, A. I.; Bakulev, V. A.

    2015-12-01

    The [2+2]-, [4+2]- and [3+2]-cycloaddition reactions of hydrazones and 1,2-diazabuta-1,3-dienes, azomethine imines, nitrile imines and azomethine ylides formed upon hydrazone transformations with dienophiles, dipolarophiles and dienes are considered. The principal issues of structure and reactivity of active substrates and the influence of the reaction conditions and catalysts on the reaction regioselectivity and efficiency are discussed. The bibliography includes 288 references.

  18. [Caloric substrates in postoperative parenteral nutrition].

    PubMed

    De Salvo, L; Romairone, E; Ansaldo, G L; Mattioli, G

    1991-05-31

    The paper describes the carbohydrate, lipidic and nitrogen metabolism of the postoperative period which is subdivided into an early and a late phase. Since the metabolism of caloric substrates in the early postoperative period is a stress metabolism with glucose intolerance and wide protein catabolism, the authors emphasise that an insufficient caloric intake is worse than the fasting state and suggest that alternative caloric sources, such as branched chain amino acids, fatty acids and, even, ketonic bodies, should be used.

  19. Creatine supplementation influences substrate utilization at rest.

    PubMed

    Huso, M Erik; Hampl, Jeffrey S; Johnston, Carol S; Swan, Pamela D

    2002-12-01

    The influence of creatine supplementation on substrate utilization during rest was investigated using a double-blind crossover design. Ten active men participated in 12 wk of weight training and were given creatine and placebo (20 g/day for 4 days, then 2 g/day for 17 days) in two trials separated by a 4-wk washout. Body composition, substrate utilization, and strength were assessed after weeks 2, 5, 9, and 12. Maximal isometric contraction [1 repetition maximum (RM)] leg press increased significantly (P < 0.05) after both treatments, but 1-RM bench press was increased (33 +/- 8 kg, P < 0.05) only after creatine. Total body mass increased (1.6 +/- 0.5 kg, P < 0.05) after creatine but not after placebo. Significant (P < 0.05) increases in fat-free mass were found after creatine and placebo supplementation (1.9 +/- 0.8 and 2.2 +/- 0.7 kg, respectively). Fat mass did not change significantly with creatine but decreased after the placebo trial (-2.4 +/- 0.8 kg, P < 0.05). Carbohydrate oxidation was increased by creatine (8.9 +/- 4.0%, P < 0.05), whereas there was a trend for increased respiratory exchange ratio after creatine supplementation (0.03 +/- 0.01, P = 0.07). Changes in substrate oxidation may influence the inhibition of fat mass loss associated with creatine after weight training.

  20. Urate as a Physiological Substrate for Myeloperoxidase

    PubMed Central

    Meotti, Flavia C.; Jameson, Guy N. L.; Turner, Rufus; Harwood, D. Tim; Stockwell, Samantha; Rees, Martin D.; Thomas, Shane R.; Kettle, Anthony J.

    2011-01-01

    Urate and myeloperoxidase (MPO) are associated with adverse outcomes in cardiovascular disease. In this study, we assessed whether urate is a likely physiological substrate for MPO and if the products of their interaction have the potential to exacerbate inflammation. Urate was readily oxidized by MPO and hydrogen peroxide to 5-hydroxyisourate, which decayed to predominantly allantoin. The redox intermediates of MPO were reduced by urate with rate constants of 4.6 × 105 m−1 s−1 for compound I and 1.7 × 104 m−1 s−1 for compound II. Urate competed with chloride for oxidation by MPO and at hyperuricemic levels is expected to be a substantive substrate for the enzyme. Oxidation of urate promoted super-stoichiometric consumption of glutathione, which indicates that it is converted to a free radical intermediate. In combination with superoxide and hydrogen peroxide, MPO oxidized urate to a reactive hydroperoxide. This would form by addition of superoxide to the urate radical. Urate also enhanced MPO-dependent consumption of nitric oxide. In human plasma, stimulated neutrophils produced allantoin in a reaction dependent on the NADPH oxidase, MPO and superoxide. We propose that urate is a physiological substrate for MPO that is oxidized to the urate radical. The reactions of this radical with superoxide and nitric oxide provide a plausible link between urate and MPO in cardiovascular disease. PMID:21266577

  1. Ultrasonic wave propagation in multilayered piezoelectric substrates

    SciTech Connect

    Chien, H.T.; Sheen, S.H.; Raptis, A.C.

    1994-04-11

    Due to the increasing demand for higher operating frequency, lower attenuation, and stronger piezoelectricity, use of the layered structure has become necessary. Theoretical studies are carried out for ultrasonic waves propagating in the multilayered piezoelectric substrates. Each layer processes up to as low as monoclinic symmetry with various thickness and orientation. A plane acoustic wave is assumed to be incident, at varied frequency and incidence angle, from a fluid upon a multilayered substrate. Simple analytical expressions for the reflection and transmission coefficients are derived from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the multilayered piezoelectric substrates. Solutions are obtained for the individual layers which relate the field variables at the upper layer surfaces. The response of the total system proceeds by satisfying appropriate interfacial conditions across the layers. Based on the boundary conditions, two cases, {open_quotes}shorted{close_quotes} and {open_quotes}free{close_quotes}, are derived from which a so-called piezoelectric coupling factor is calculated to show the piezoelectric efficiency. Our results are rather general and show that the phase velocity is a function of frequency, layer thickness, and orientation.

  2. Multilayer deformation planarization by substrate pit suturing.

    PubMed

    Chai, Yingjie; Zhu, Meiping; Xing, Huanbin; Wang, Hu; Cui, Yun; Shao, Jianda

    2016-08-01

    In the pursuit of 1064 nm high-power laser resistance dielectric coatings in the nanosecond region, a group of HfO2/SiO2 high reflectors with and without suture layers were prepared on prearranged fused silica substrates with femtosecond laser pits. Surface morphology, global coating stress, and high-resolution cross sections were characterized to determine the effects of substrate pit suturing. Laser-induced damage resistance was investigated for samples with and without suture layers. Our results indicate considerable stability in terms of the nanosecond 1064 nm laser-induced damage threshold for samples having a suture layer, due to decreased electronic field (e-field) deformation with simultaneous elimination of internal cracks. In addition, a suture layer formed by plasma ion-assisted deposition could effectively improve global mechanical stress of the coatings. By effectively reducing the multilayer deformation using a suture layer, electron-beam high-reflective coatings, whose laser-induced damage resistance was not influenced by the substrate pit, can be prepared.

  3. Laminate articles on biaxially textured metal substrates

    DOEpatents

    Beach, David B.; Morrell, Jonathan S.; Paranthaman, Mariappan; Chirayil, Thomas; Specht, Eliot D.; Goyal, Amit

    2003-12-16

    A laminate article comprises a substrate and a biaxially textured (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer over the substrate, wherein 0substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  4. Cell-Substrate Adhesion by Amoeboid Cells

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Panta, Krishna

    Amoeboid migration is a rapid (10 μm min-1) mode of migration that some tumor cells exhibit. To permit such rapid movement, the adhesive contacts between the cell and the substrate must be relatively short-lived and weak. In this study, we investigate the basic adhesive character of amoeboid cells (D. discoideum) in contact with silanized glass substrates. We observe the initiation and spreading of the adhesive contacts that these cells establish as they settle under gravity onto the substrate and relax towards mechanical equilibrium. The use of interference reflection microscopy and cellular tethering measurements have allowed us to determine the basic adhesive properties of the cell: the membrane-medium interfacial energy; the bending modulus; the equilibrium contact angle; and the work of adhesion. We find the time scale on which settling occurs to be longer than expected. Implications of these results on adhesion and migration will be discussed. The authors are grateful for support from NSF (CBET-1451903) and NIH (1R21EY026392).

  5. Substrate dependence of graphene reactivity towards hydrogenation

    NASA Astrophysics Data System (ADS)

    Son, S.; Holroyd, C.; Clough, J.; Horn, A.; Koehler, S. P. K.; Casiraghi, C.

    2016-12-01

    The ability to functionalize graphene with several methods, such as radical reactions, cyclo-additions, hydrogenation, and oxidations, allows this material to be used in a large range of applications. In this framework, it is essential to be able to control the efficiency and stability of the functionalization process—this requires understanding how the graphene reactivity is affected by the environment, including the substrate. In this work we provide an insight on the substrate dependence of graphene reactivity towards hydrogenation by comparing three different substrates: silicon, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2). Although MoS2 and h-BN have flatter surfaces than silicon, we found that the H coverage of graphene on h-BN is about half of the H coverage on graphene on both silicon and MoS2. Therefore, graphene shows strongly reduced reactivity towards hydrogenation when placed on h-BN. The difference in hydrogenation reactivity between h-BN and MoS2 may indicate a stronger van der Waals force between graphene and h-BN, compared to MoS2, or may be related to the chemical properties of MoS2, which is a well-known catalyst for hydrogen evolution reactions.

  6. Improvement of mechanical properties of glass substrates

    NASA Astrophysics Data System (ADS)

    Karbay, Ismail Hakki Cengizhan; Budakoglu, Refika; Zayim, Esra Ozkan

    2015-12-01

    This paper aims to enhance the mechanical and optical properties of glass substrates with thin films by the sol-gel method. TiO2-SiO2 binary system and Ta2O5 were deposited on glass substrates with high transparency. Ring-on-ring flexure and scratch tests were the main mechanical characterization tests. Herein, we report that the thin films can be used to enhance the mechanical properties of the glass substrates efficiently and effectively. TiO2-SiO2 binary system shows more than two times and Ta2O5 thin films show nearly three times better ultimate strength in the ring-on-ring flexure test. Besides, Ta2O5 thin film samples show superior scratch resistance. Additionally, the finite element method was also used to check the conformity in the application of mechanical properties of composite materials. It is also worth noting that, the finite element method can be used to accurately analyze the mechanical stability of composite materials. The use of the finite element method can reduce the total number of experimental trials without losing reliability.

  7. Influence of Substrate Composition on Marine Microfouling †

    PubMed Central

    Marszalek, Donald S.; Gerchakov, Sol M.; Udey, Lanny R.

    1979-01-01

    Glass and metal substrates exposed to subtropical seawater exhibit a characteristic succession of periphytic microorganisms. Substrates which are biologically and physically inert (glass and stainless steel) fouled rapidly and produced a complex, two-tier microfouling layer. Characteristic microorganisms were bacteria, fungi, choanoflagellates, diatoms, ciliates, and microalgae. Active substrates (brass and copper-nickel alloys) were selective for bacteria which secrete extracellular mucoid material, fouled at a slower rate, and were characterized by a less diverse microfouling community. Substrate appears to influence microfouling at all stages of development, especially in the early stages of substrate conditioning, and primary film formation. Primary films may insulate periphytic microorganisms from toxic substrates. Images PMID:16345467

  8. Spectral Markers of Erythrocytes on Solid Substrate

    NASA Astrophysics Data System (ADS)

    Paiziev, Adkhamjon A.; Krakhmalev, V. A.

    Proposed in previous paper [1,2] the new nondestructive method of optical microscopy allows to examine the structures of living cells (human erythrocytes) in their natural colors without its staining by using a specially designed substrate for deposition of biological sample and observing a native blood smears in reflected light. Color interference contrast image is achieved due to special condition of experiment is connected with chose of angle of incidental light, wave length of light of reflected ray, chemical composition of sample, thickness of sample, refractive index of sample, refractive index of substrate, chemical composition of substrate [1,2]. We can identify chemical compounds of erythrocytes after calibration color scale by alternative methods. For comparison we used Synchrotron Radiation based Fourier Transformed Infrared (SR-FTIR) microspectroscopy. By focusing of infrared beam of FTIR microscope on cell surface we can screen and distinguish difference erythrocytes by its color. For example on Fig. 49.1 we can see two neighbored erythrocytes where one of them have red color (point 1) and other-green (point 5). To identify their spectral markers we measured IR absorption spectra of cells at different points (1,2,3,4 and 5). Intermediated area (points 3 and 4) correspond to substrate spectra (silicon substrate) and their spectra are same. The peaks at 2,850 and 2,920 cm-1 correspond mainly to the CH2 stretching modes of the methylene chains in membrane lipids. At 1,650 cm-1 the amide I band is observed, which results, principally, from the n(CO) stretching vibrations of the protein amide bonds; the amide II band, near 1,550 cm-1, is a combination of the d(N-H) bending and n(C-N) stretching vibrations of the amide bonds. The peaks at 2,850 and 2,920 cm-1 correspond mainly to the CH2 stretching modes of the methylene chains in membrane lipids [3. The intensities of the absorption bands at 2,920 and 2,850 cm-1 in green erythrocyte (point 5) were also

  9. Modeling substrate-bacteria-grazer interactions coupled to substrate transport in groundwater

    NASA Astrophysics Data System (ADS)

    Bajracharya, Bijendra M.; Lu, Chuanhe; Cirpka, Olaf A.

    2014-05-01

    Models of microbial dynamics coupled to solute transport in aquifers typically require the introduction of a bacterial capacity term to prevent excessive microbial growth close to substrate-injection boundaries. The factors controlling this carrying capacity, however, are not fully understood. In this study, we propose that grazers or bacteriophages may control the density of bacterial biomass in continuously fed porous media. We conceptualize the flow-through porous medium as a series of retentostats, in which the dissolved substrate is advected with water flow whereas the biomasses of bacteria and grazers are considered essentially immobile. We first model a single retentostat with Monod kinetics of bacterial growth and a second-order grazing law, which shows that the system oscillates but approaches a stable steady state with nonzero concentrations of substrate, bacteria, and grazers. The steady state concentration of the bacteria biomass is independent of the substrate concentration in the inflow. When coupling several retentostats in a series to mimic a groundwater column, the steady state bacteria concentrations thus remain at a constant level over a significant travel distance. The one-dimensional reactive transport model also accounts for substrate dispersion and a random walk of grazers influenced by the bacteria concentration. These dispersive-diffusive terms affect the oscillations until steady state is reached, but hardly the steady state value itself. We conclude that grazing, or infection by bacteriophages, is a possible explanation of the maximum biomass concentration frequently needed in bioreactive transport models. Its value depends on parameters related to the grazers or bacteriophages and is independent of bacterial growth parameters or substrate concentration, provided that there is enough substrate to sustain bacteria and grazers.

  10. Structural insights into substrate traffic and inhibition in acetylcholinesterase

    PubMed Central

    Colletier, Jacques-Philippe; Fournier, Didier; Greenblatt, Harry M; Stojan, Jure; Sussman, Joel L; Zaccai, Giuseppe; Silman, Israel; Weik, Martin

    2006-01-01

    Acetylcholinesterase (AChE) terminates nerve-impulse transmission at cholinergic synapses by rapid hydrolysis of the neurotransmitter, acetylcholine. Substrate traffic in AChE involves at least two binding sites, the catalytic and peripheral anionic sites, which have been suggested to be allosterically related and involved in substrate inhibition. Here, we present the crystal structures of Torpedo californica AChE complexed with the substrate acetylthiocholine, the product thiocholine and a nonhydrolysable substrate analogue. These structures provide a series of static snapshots of the substrate en route to the active site and identify, for the first time, binding of substrate and product at both the peripheral and active sites. Furthermore, they provide structural insight into substrate inhibition in AChE at two different substrate concentrations. Our structural data indicate that substrate inhibition at moderate substrate concentration is due to choline exit being hindered by a substrate molecule bound at the peripheral site. At the higher concentration, substrate inhibition arises from prevention of exit of acetate due to binding of two substrate molecules within the active-site gorge. PMID:16763558

  11. Does the Dirac cone of germanene exist on metal substrates?

    PubMed

    Wang, Yangyang; Li, Jingzhen; Xiong, Junhua; Pan, Yuanyuan; Ye, Meng; Guo, Ying; Zhang, Han; Quhe, Ruge; Lu, Jing

    2016-07-28

    Germanene, a germanium analogue of graphene and silicene, has been synthesized on metal substrates. It is predicted that the intrinsic germanene has a Dirac cone in its band structure, just like graphene and silicene. Using first-principles calculations, we investigate the geometrical structures and electronic properties of germanene on the Ag, Au, Cu, Al, Pt and Ir substrates. The Dirac cone of germanene is destroyed on the Al, Pt and Ir substrates but preserved on the Ag and Au substrates with a slight band hybridization. The upper part of the Dirac cone is destroyed for germanene on the Cu substrate while the lower part remains preserved. By contrast, the Dirac cone is always destroyed for silicene on these metal substrates because of a strong band hybridization. Our study suggests that it is possible to extract the intrinsic properties of germanene on the Ag and Au substrates although it appears impossible for silicene on these two substrates.

  12. Substrate effects on glass formation in simple monatomic supercooled liquids

    NASA Astrophysics Data System (ADS)

    Hoang, Vo Van; Thoa, Dao Kim; Odagaki, Takashi; Qui, Le Ngoc

    2015-02-01

    Glass formation in simple monatomic supercooled liquids on substrate is studied via molecular dynamics simulations. We find that glass formation in thin films on substrate exhibits a 'heterogeneous' behavior, i.e. solidlike atoms initiate/enhance simultaneously in the near substrate region and in the interior of the system, then solidlike domain grows outward to the free surface. Substrate causes strong layering of the near substrate region of liquid and glass. Layering is enhanced with decreasing temperature and layering region exhibits a glassy behavior instead of crystalline one. We find that structure and dynamics of liquid and glass in the near substrate region is different from those of the remaining part of thin films. This means that thin films formed on substrate can be divided into three distinct parts: near substrate region, interior and free surface region. We find a significant amount of liquidlike atoms even at T

  13. Silencer! A Tool for Substrate Noise Coupling Analysis

    DTIC Science & Technology

    2004-01-09

    high electric fields, electrons achieve high velocities and collide with silicon atoms in the substrate. Such collisions can create electron-hole...ports ( SC_Chip drawing ) ;Added substrate ports ( specres drawing ) ( tight

  14. Surface control alloy substrates and methods of manufacture therefor

    DOEpatents

    Fritzemeier, Leslie G.; Li, Qi; Rupich, Martin W.; Thompson, Elliott D.; Siegal, Edward J.; Thieme, Cornelis Leo Hans; Annavarapu, Suresh; Arendt, Paul N.; Foltyn, Stephen R.

    2004-05-04

    Methods and articles for controlling the surface of an alloy substrate for deposition of an epitaxial layer. The invention includes the use of an intermediate layer to stabilize the substrate surface against oxidation for subsequent deposition of an epitaxial layer.

  15. Association of endogenous substrate with solubilized bovine brain sialidase.

    PubMed

    Schengrund, C L; Repman, M A

    1986-01-01

    Nonidet P40 solubilized up to 90% of the sialidase, active towards added ganglioside substrate, that was associated with the total membrane fraction prepared from gray matter of bovine brains. Solubilized sialidase acted upon endogenous substrate (sialic acid containing compounds solubilized with the enzyme), hydrolyzing approximately 50% of the readily available sialosyl residues within 20 min. During a 2-hr reaction time 80% of the polysialylated gangliosides solubilized with the enzyme were acted upon. A 20-min lag was observed before sialidase acted upon added ganglioside substrate. The lag could be reduced to less than 2 min when the enzyme was allowed to act on endogenous substrate prior to exposure to exogenous substrate, suggesting that the solubilized enzyme acted preferentially on endogenous substrate. A protease inhibitor prevented much of the 86% loss of activity towards added substrate that was seen when the enzyme was stored at 4 degrees C for 6 days; activity towards endogenous substrate decreased only 34%.

  16. Substrate specificities of cutinases on aliphatic-aromatic polyesters and on their model substrates.

    PubMed

    Perz, Veronika; Bleymaier, Klaus; Sinkel, Carsten; Kueper, Ulf; Bonnekessel, Melanie; Ribitsch, Doris; Guebitz, Georg M

    2016-03-25

    The enzymatic hydrolysis of the biodegradable polyester ecoflex and of a variety of oligomeric and polymeric ecoflex model substrates was investigated. For this purpose, substrate specificities of two enzymes of typical compost inhabitants, namely a fungal cutinase from Humicola insolens (HiC) and a bacterial cutinase from Thermobifida cellulosilytica (Thc_Cut1) were compared. Model substrates were systematically designed with variations of the chain length of the alcohol and the acid as well as with varying content of the aromatic constituent terephthalic acid (Ta). HPLC/MS identification and quantification of the hydrolysis products terephthalic acid (Ta), benzoic acid (Ba), adipic acid (Ada), mono(4-hydroxybutyl) terephthalate (BTa), mono-(2-hydroxyethyl) terephthalate (ETa), mono-(6-hydroxyhexyl) terephthalate (HTa) and bis(4-hydroxybutyl) terephthalate (BTaB) indicated that these enzymes indeed hydrolyze the tested esters. Shorter terminal chain length acids but longer chain length alcohols in oligomeric model substrates were generally hydrolyzed more efficiently. Thc_Cut1 hydrolyzed aromatic ester bonds more efficiently than HiC resulting in up to 3-fold higher concentrations of the monomeric hydrolysis product Ta. Nevertheless, HiC exhibited a higher overall hydrolytic activity on the tested polyesters, resulting in 2-fold higher concentration of released molecules. Thermogravimetry and differential scanning calorimetry (TG-DSC) of the polymeric model substrates revealed a general trend that a lower difference between melting temperature (Tm) and the temperature at which the enzymatic degradation takes place resulted in higher susceptibility to enzymatic hydrolysis.

  17. Structural insights into Parkin substrate lysine targeting from minimal Miro substrates

    PubMed Central

    Klosowiak, Julian L.; Park, Sungjin; Smith, Kyle P.; French, Michael E.; Focia, Pamela J.; Freymann, Douglas M.; Rice, Sarah E.

    2016-01-01

    Hereditary Parkinson’s disease is commonly caused by mutations in the protein kinase PINK1 or the E3 ubiquitin ligase Parkin, which function together to eliminate damaged mitochondria. PINK1 phosphorylates both Parkin and ubiquitin to stimulate ubiquitination of dozens of proteins on the surface of the outer mitochondrial membrane. However, the mechanisms by which Parkin recognizes specific proteins for modification remain largely unexplored. Here, we show that the C-terminal GTPase (cGTPase) of the Parkin primary substrate human Miro is necessary and sufficient for efficient ubiquitination. We present several new X-ray crystal structures of both human Miro1 and Miro2 that reveal substrate recognition and ubiquitin transfer to be specific to particular protein domains and lysine residues. We also provide evidence that Parkin substrate recognition is functionally separate from substrate modification. Finally, we show that prioritization for modification of a specific lysine sidechain of the cGTPase (K572) within human Miro1 is dependent on both its location and chemical microenvironment. Activation of Parkin by phosphorylation or by binding of pUb is required for prioritization of K572 for modification, suggesting that Parkin activation and acquisition of substrate specificity are coupled. PMID:27605430

  18. Droplet wetting transitions on inclined substrates in the presence of external shear and substrate permeability

    NASA Astrophysics Data System (ADS)

    Espin, Leonardo; Kumar, Satish

    2016-11-01

    Understanding the gravity-driven motion of droplets on inclined substrates in the presence of external shear and substrate permeability is important for applications such as spray coating and filtration. In this work, we use a lubrication-theory-based model to study how external shear and substrate permeability affect droplet wetting transitions. A nonlinear evolution equation for the droplet height as a function of time and two spatial variables is derived and numerically solved. The contact-line region is described using a precursor film and disjoining pressure. Depending on its direction, external shear can either suppress or drive wetting transitions, but does not appear to significantly change the critical droplet speeds associated with these transitions. Substrate permeability generally suppresses wetting transitions due to liquid absorption and does appear to significantly affect these critical droplet speeds. The strong influence of substrate permeability and external shear on droplet wetting transitions indicates that it will be important to account for these effects when developing accurate models for industrial applications.

  19. Droplet wetting transitions on inclined substrates in the presence of external shear and substrate permeability

    NASA Astrophysics Data System (ADS)

    Espín, Leonardo; Kumar, Satish

    2017-01-01

    Understanding the gravity-driven motion of droplets on inclined substrates in the presence of external shear and substrate permeability is important for applications such as spray coating and filtration. In this paper, we use a lubrication-theory-based model to study how external shear and substrate permeability affect droplet wetting transitions. A nonlinear evolution equation for the droplet height as a function of time and two spatial variables is derived and numerically solved. The contact-line region is described using a precursor film and disjoining pressure. Depending on its direction, external shear can either suppress or drive wetting transitions, but does not appear to significantly change the critical droplet speeds associated with these transitions. Substrate permeability generally suppresses wetting transitions due to liquid absorption and does appear to significantly affect these critical droplet speeds. The strong influence of substrate permeability and external shear on droplet wetting transitions indicates that it will be important to account for these effects when developing accurate models for industrial applications.

  20. Report on EUVL Mask Substrate Development: Low-Expansion Substrate Finishing II

    SciTech Connect

    Tong, W.M.; Taylor, J.S.; Hector, S.D.; Shell, M.

    1999-12-08

    This report is a continuation of our assessment of the finishing of low thermal expansion material wafers obtained through three different commercial pathways. This quarter we have patterned and printed a ULE{reg_sign} wafer (Rodel 1) and saw no difference between its images and those from silicon wafer substrates. This further demonstrated that ULE{reg_sign} can be used as the EUVL mask substrate material. We have also evaluated substrates produced by three vendors: Hoya, General Optics, and Rodel. Consistent with our results reported last quarter, surface roughness of the bare substrates from all three companies does not depend on the position. For Hoya, the wafers it produced had a low roughness than those from last quarter. However, the cleanliness of the wafers needs to be improved. For General Optics, the wafer roughness has increased, and it was only able to deliver one wafer this quarter. General Optics will be replaced by Schott ML next quarter. For Rodel, one of its wafers (Rodel 1) that had been cleaned in-house showed excellent finishing and was selected to be patterned. We also observed that the sleeks on the substrates were smoothed by the ML coating. The other two Rodel wafers (Rodel 2 and Rodel 4) had too many defects and the roughness values derived from AFM are not reliable.

  1. Rich variety of substrates for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Nguyen, Bich Ha; Hieu Nguyen, Van; Nhung Tran, Hong

    2016-09-01

    The efficiency of the application of surface enhanced Raman spectroscopy (SERS) technique to each specified purpose significantly depends on the choice of the SERS substrate with an appropriate structure as well as on its performance. Until the present time a rich variety of SERS substrates was fabricated. They can be classified according to their structures. The present work is a review of main types of SERS substrates for using in the trace analysis application. They can be classified into 4 groups: (1) Substrates using gold nanoparticles (AuNPs) with spherical shape such as colloidal AuNPs, AuNPs fabricated by pulsed laser deposition, by sputtering or by capillary force assembly (CFA), substrates fabricated by electrospinning technique, substrates using metallic nanoparticle arrays fabricated by electron beam lithography combined with CFA method, substrates using silver nanoparticle (AgNP) arrays grain by chemical seeded method, substrates with tunable surface plasmon resonance, substrates based on precies subnanometer plasmonic junctions within AuNP assemblies, substrates fabricated by simultaneously immobilizing both AuNPs and AgNPs on the same glass sides etc. (2) Substrates using nanostructures with non-spherical shapes such as gold nanowire (NW), or highly anisotropic nickel NW together with large area, free-standing carpets, substrates with obviously angular, quasi-vertically aligned cuboid-shaped TiO2 NW arrays decorated with AgNPs, substrates using gold nanoprism monolayer films, substrates using silver nanocube dimmers or monodisperse close-packed gold nanotriangle monolayers. (3) Substrates using multiparticle complex nanostructure such as nanoparticle cluster arrays, gold nanoflowers and nanodendrites. (4) Flexible substrate such as paper-based swab with gold nanorods, adhesive polymer tapes fabricated by inkjet printing method and flexible and adhesive SERS tapes fabricated by decorating AuNPs via the conventional drop-dry method.

  2. Surface-grafted polypeptides on flat substrates

    NASA Astrophysics Data System (ADS)

    Wang, Yuli

    In this work, we improved the vapor deposition-polymerization (VDP) technique by re-designing a new vacuum chamber, and adding two heating plates to control the temperatures of the substrate and monomer evaporation. By optimizing the reaction parameters such as monomer amount, substrate temperature and reaction time, various polypeptides with sufficiently high molecular weight have been successfully grafted onto the solid substrates. The combination of VPD with photolithography has fabricated micro-patterned polypeptides, with geometry patternable in both lateral and vertical directions. Next, the conformations of the surface-grafted polypeptides were systematically examined. New ways have been found to switch their conformations between alpha-helix and beta-sheet, or between right-handed helix and left-handed helix. Two important ionic polypeptides, poly(L-glutamic acid) (PLGA) and poly(L-lysine) (PLL) were the focuses of this work. The conformational transitions of surface-grafted PLGA and PLL were successfully induced by pH, surfactants and ions. In addition, a surface-grafted PLGA-block-PLL copolypeptide was studied. Their unexpected pH-responsiveness was explained by the beta-sheet formation between the PLGA and PLL blocks. The orientation of the surface-grafted alpha-helical poly(gamma-benzyl L-glutamate) (PBLG) was greatly improved by a novel "solvent quenching" method, which involves treating the film sequentially with a good solvent and a poor solvent. The average tilt angle of the PBLG rods changed from 49° to 3° by applying this "quenching". Finally, a surface-grafted PLL film was used as the template to mimic the biosilicification. Silica was spontaneously synthesized from tetraethoxysilane inside the PLL film at room temperature and at neutral pH.

  3. Hetero epitaxial graphene on various substrates

    NASA Astrophysics Data System (ADS)

    Harris, Gary; Kaut, Gurpreet; Taylor, Crawford

    2015-03-01

    Large-scale production of graphene is pivotal for the development of graphene-based electronics. These results focus on the synthesis and characterization of graphene layers. Two methods were used to grow graphene films. First, graphene films were epitaxially grown on silicon carbide substrates by thermal decomposition of SiC at high temperature and low pressure. In-house built reactor consisting of induction furnace was used to form epitaxial films for electronic applications. Second, chemical vapor deposition method was used for direct graphene synthesis on 3C-SiC with the use of copper as a catalyst. In thermal CVD process, hydrogen and methane gases were used as precursors. Methane acts as a carbon source and annealing and cooling were done hydrogen environment. Different polytypes of silicon carbide (6H-SiC and 3C-SiC) and their crystal orientations were exploited as substrates to form epitaxial graphene. Hetero epitaxial 3C-SiC epilayer was first deposited on Si substrate using chemical vapor deposition technique in cold wall, low pressure, and horizontal CVD reactor. The reactor temperature, argon pressure, flow rates and concentration of different gases (propane, silane, hydrogen and argon) was investigated to control the growth of 3C-SiC and silicon sublimation rate. The resulting graphene films were confirmed using Raman spectroscopy. Further, graphene films have been characterized with the tools of atomic force microscopy (AFM) and scanning electron microscopy (SEM). Mobility, electrical resistivity and carrier density measurements were taken using hall measurements. NSF_PRDM

  4. Molybdenum protective coatings adhesion to steel substrate

    NASA Astrophysics Data System (ADS)

    Blesman, A. I.; Postnikov, D. V.; Polonyankin, D. A.; Teplouhov, A. A.; Tyukin, A. V.; Tkachenko, E. A.

    2017-06-01

    Protection of the critical parts, components and assemblies from corrosion is an urgent engineering problem and many other industries. Protective coatings’ forming on surface of metal products is a promising way of corrosionprevention. The adhesion force is one of the main characteristics of coatings’ durability. The paper presents theoretical and experimental adhesion force assessment for coatings formed by molybdenum magnetron sputtering ontoa steel substrate. Validity and reliability of results obtained by simulation and sclerometry method allow applying the developed model for adhesion force evaluation in binary «steel-coating» systems.

  5. Tunable dielectric liquid lens on flexible substrate

    PubMed Central

    Lu, Yen-Sheng; Tu, Hongen; Xu, Yong; Jiang, Hongrui

    2013-01-01

    We demonstrate the fabrication of a tunable-focus dielectric liquid lens (DLL) on a flexible substrate made of polydimethylsiloxane, which was wrapped onto a goggle surface to show its functionality. As a positive meniscus converging lens, the DLL has the focal length variable from 14.2 to 6.3 mm in 1.3 s when the driving voltage increases to 125 Vrms. The resolving power of the DLL is 17.95 line pairs per mm. The DLL on a flexible, curvilinear surface is promising for expanded field of view covered as well as in reconfigurable optical systems. PMID:24493877

  6. Graphene as a substrate for plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Polyushkin, Dmitry K.; Milton, James; Santandrea, Salvatore; Russo, Saverio; Craciun, Monica F.; Green, Stephen J.; Mahe, Laureline; Winolve, C. Peter; Barnes, William L.

    2013-11-01

    We report results from an investigation into the plasmonic properties of metallic nanoparticles supported by graphene fabricated using two different methods. In the first method we used electron-beam lithography to produce ordered arrays of metallic nanoparticles. In the second method we used a technique based on electrochemistry to produce random arrangements of metallic nanoparticles. Our results show that both pristine graphene and a more conducting intercalated variant are excellent substrates for plasmonic nanoparticles owing to their transparency and atomically thin nature, opening an interesting route for building plasmon-based bio- and chemical-sensors, and for developing transparent and flexible optoelectronics.

  7. Elastomeric silicone substrates for terahertz fishnet metamaterials

    NASA Astrophysics Data System (ADS)

    Khodasevych, I. E.; Shah, C. M.; Sriram, S.; Bhaskaran, M.; Withayachumnankul, W.; Ung, B. S. Y.; Lin, H.; Rowe, W. S. T.; Abbott, D.; Mitchell, A.

    2012-02-01

    In this work, we characterize the electromagnetic properties of polydimethylsiloxane (PDMS) and use this as a free-standing substrate for the realization of flexible fishnet metamaterials at terahertz frequencies. Across the 0.2-2.5 THz band, the refractive index and absorption coefficient of PDMS are estimated as 1.55 and 0-22 cm-1, respectively. Electromagnetic modeling, multi-layer flexible electronics microfabrication, and terahertz time-domain spectroscopy are used in the design, fabrication, and characterization of the metamaterials, respectively. The properties of PDMS add a degree of freedom to terahertz metamaterials, with the potential for tuning by elastic deformation or integrated microfluidics.

  8. Metallic substrates for high temperature superconductors

    DOEpatents

    Truchan, Thomas G.; Miller, Dean J.; Goretta, Kenneth C.; Balachandran, Uthamalingam; Foley, Robert

    2002-01-01

    A biaxially textured face-centered cubic metal article having grain boundaries with misorientation angles greater than about 8.degree. limited to less than about 1%. A laminate article is also disclosed having a metal substrate first rolled to at least about 95% thickness reduction followed by a first annealing at a temperature less than about 375.degree. C. Then a second rolling operation of not greater than about 6% thickness reduction is provided, followed by a second annealing at a temperature greater than about 400.degree. C. A method of forming the metal and laminate articles is also disclosed.

  9. Metal Enhanced Fluorescence on Silicon Wafer Substrates

    PubMed Central

    Gryczynski, I.; Matveeva, E.G.; Sarkar, P.; Bharill, S.; Borejdo, J.; Mandecki, W.; Akopova, I.; Gryczynski, Z.

    2008-01-01

    We report on the fluorescence enhancement induced by silver island film (SIF) deposited on a silicon wafer. The model immunoassay was studied on silvered and unsilvered wafers. The fluorescence brightness of Rhodamine Red X increased about 300% on the SIF, while the lifetime was reduced by several fold and the photostability increased substantially. We discuss potential uses of silicon wafer substrates in multiplex assays in which the fluorescence is enhanced due to the SIF, and the multiplexing is achieved by using micro transponders. PMID:19137060

  10. Thin film reactions on alloy semiconductor substrates

    SciTech Connect

    Olson, D.A.

    1990-11-01

    The interactions between Pt and In{sub .53}Ga{sub .47}As have been studied. In{sub .53}Ga{sub .47}As substrates with 70nm Pt films were encapsulated in SiO{sub 2}, and annealed up to 600{degree}C in flowing forming gas. The composition and morphology of the reaction product phases were studied using x-ray diffraction, Auger depth profiling, and transmission electron microscopy. The reaction kinetics were examined with Rutherford Backscattering. Results show that Pt/In{sub .53}Ga{sub .47}As reacts to form many of the reaction products encountered in the Pt/GaAs and Pt/InP reactions: PtGa, Pt{sub 3}Ga, and PtAs{sub 2}. In addition, a ternary phase, Pt(In:Ga){sub 2}, develops, which is a solid solution between PtIn{sub 2} and PtGa{sub 2}. The amount of Ga in the ternary phase increases with annealing temperature, which causes a decrease in the lattice parameter of the phase. The reaction products show a tendency to form layered structures, especially for higher temperatures and longer annealing times. Unlike the binary case, the PtAs{sub 2}, phase is randomly oriented on the substrate, and is intermingle with a significant amount of Pt(In:Ga){sub 2}. Following Pt/In{sub .53}Ga{sub .47}As reactions, two orientation relationships between the Pt(In:Ga){sub 2} product phase and the substrate were observed, despite the large mismatch with the substrate ({approximately}8%). For many metal/compound semiconductor interactions, the reaction rate is diffusion limited, i.e. exhibits a parabolic dependence on time. An additional result of this study was the development of an In-rich layer beneath the reacted layer. The Auger depth profile showed a substantial increase in the sample at this layer. This is a significant result for the production of ohmic contacts, as the Schottky barrier height in this system lower for higher In concentrations. 216 refs.

  11. Palladium on plastic substrates for plasmonic devices.

    PubMed

    Zuppella, Paola; Pasqualotto, Elisabetta; Zuccon, Sara; Gerlin, Francesca; Corso, Alain Jody; Scaramuzza, Matteo; De Toni, Alessandro; Paccagnella, Alessandro; Pelizzo, Maria Guglielmina

    2015-01-09

    Innovative chips based on palladium thin films deposited on plastic substrates have been tested in the Kretschmann surface plasmon resonance (SPR) configuration. The new chips combine the advantages of a plastic support that is interesting and commercially appealing and the physical properties of palladium, showing inverted surface plasmon resonance (ISPR). The detection of DNA chains has been selected as the target of the experiment, since it can be applied to several medical early diagnostic tools, such as different biomarkers of cancers or cystic fibrosis. The results are encouraging for the use of palladium in SPR-based sensors of interest for both the advancement of biodevices and the development of hydrogen sensors.

  12. Gas microstrip detectors on resistive plastic substrates

    SciTech Connect

    Dixit, M.S.; Oakham, F.G.; Armitage, J.C.

    1993-12-31

    Plastics are desirable as substrates for gas microstrip detectors (GMDs) because of their flexibility, low density and long radiation length. GMDs have been fabricated on white Tedlar which has bulk electrical conductivity and ion-implanted Upilex which has a thin electrically conductive layer on the surface of an insulator. The effect of back plane voltage on the gain of such GMDs is investigated. Three 200 {mu}m pitch, ion-implanted Upilex GMDs were recently tested in a high intensity beam at CERN. The anode signals were read out using fast, low noise, high gain amplifiers. Preliminary results of the test are presented.

  13. Substrate Binding Mechanism of a Type I Extradiol Dioxygenase*

    PubMed Central

    Cho, Hyo Je; Kim, Kyungsun; Sohn, Seo Yean; Cho, Ha Yeon; Kim, Kyung Jin; Kim, Myung Hee; Kim, Dockyu; Kim, Eungbin; Kang, Beom Sik

    2010-01-01

    A meta-cleavage pathway for the aerobic degradation of aromatic hydrocarbons is catalyzed by extradiol dioxygenases via a two-step mechanism: catechol substrate binding and dioxygen incorporation. The binding of substrate triggers the release of water, thereby opening a coordination site for molecular oxygen. The crystal structures of AkbC, a type I extradiol dioxygenase, and the enzyme substrate (3-methylcatechol) complex revealed the substrate binding process of extradiol dioxygenase. AkbC is composed of an N-domain and an active C-domain, which contains iron coordinated by a 2-His-1-carboxylate facial triad motif. The C-domain includes a β-hairpin structure and a C-terminal tail. In substrate-bound AkbC, 3-methylcatechol interacts with the iron via a single hydroxyl group, which represents an intermediate stage in the substrate binding process. Structure-based mutagenesis revealed that the C-terminal tail and β-hairpin form part of the substrate binding pocket that is responsible for substrate specificity by blocking substrate entry. Once a substrate enters the active site, these structural elements also play a role in the correct positioning of the substrate. Based on the results presented here, a putative substrate binding mechanism is proposed. PMID:20810655

  14. Simplified Treatment of Two-Substrate Enzyme Kinetics.

    ERIC Educational Resources Information Center

    Splittgerber, Allan G.

    1983-01-01

    Presented is a possible approach to the classroom treatment of enzyme kinetics at the two-substrate level. Areas discussed include single substrate cases, two substrate cases, Cleland's rules, dead end inhibition, inhibitor complexing with more than one enzyme form, and product inhibition. (JN)

  15. Simplified Treatment of Two-Substrate Enzyme Kinetics.

    ERIC Educational Resources Information Center

    Splittgerber, Allan G.

    1983-01-01

    Presented is a possible approach to the classroom treatment of enzyme kinetics at the two-substrate level. Areas discussed include single substrate cases, two substrate cases, Cleland's rules, dead end inhibition, inhibitor complexing with more than one enzyme form, and product inhibition. (JN)

  16. Graphene-on-semiconductor substrates for analog electronics

    DOEpatents

    Lagally, Max G.; Cavallo, Francesca; Rojas-Delgado, Richard

    2016-04-26

    Electrically conductive material structures, analog electronic devices incorporating the structures and methods for making the structures are provided. The structures include a layer of graphene on a semiconductor substrate. The graphene layer and the substrate are separated by an interfacial region that promotes transfer of charge carriers from the surface of the substrate to the graphene.

  17. Methods for both coating a substrate with aluminum oxide and infusing the substrate with elemental aluminum

    DOEpatents

    Choi, Jung-Pyung; Weil, Kenneth Scott

    2016-11-01

    Methods of aluminizing the surface of a metal substrate. The methods of the present invention do not require establishment of a vacuum or a reducing atmosphere, as is typically necessary. Accordingly, aluminization can occur in the presence of oxygen, which greatly simplifies and reduces processing costs by allowing deposition of the aluminum coating to be performed, for example, in air. Embodiments of the present invention can be characterized by applying a slurry that includes a binder and powder granules containing aluminum to the metal substrate surface. Then, in a combined step, a portion of the aluminum is diffused into the substrate and a portion of the aluminum is oxidized by heating the slurry to a temperature greater than the melting point of the aluminum in an oxygen-containing atmosphere.

  18. [Interaction of substrates and substrate-like inhibitors with the peptidyltransferase center from Escherichia coli ribosomes].

    PubMed

    Kukhanova, M K; Burd, S B; Viktorova, L S; Nechipurenko, Iu D; Gottikh, B P

    1984-01-01

    The binding isotherms of CACCA(3'NHPhe----Ac) and CACCA(3'NHPhe) to E. coli ribosomes and 50S subunits were measured. A theoretical model of adsorption for the case of cooperative interaction between two ligands adsorbed on a ribosome was designated. The analysis of the experimental binding isoterms leads to the following conclusions. A ribosome (or subunit) binds one CACCA (3'NHPhe----Ac) molecule to donor site of the peptidyl transferase center, but two CACCA (3'NHPhe) molecules to both donor and acceptor sites. The binding of CACCA (3'NHPhe) to ribosomes (or subunits) is a cooperative process, characterized by the cooperativity coefficient tau = 40 +/- 5 or more. When model substrates CACCA-Phe, CACCA-Leu and CACCA-Val were taken instead of CACCA (3'NHPhe) in the incubation mixture with ribosomes, dipeptides were obtained even in the case, when ratio [model substrate]: [ribosome] (in moles) was much lower than 1. Puromycin binding to acceptor site with constant (1-2) X 10(4) M-1 also stimulates CACCA(3'NHPhe----Ac) adsorption to the donor site of ribosomes with cooperativity coefficient being equal to 1.5-2.5. It is also shown that cytidine 5'-phosphate binding to the donor site increases kappa cat of the reaction of minimal donors with CACCA-Phe by 1.5 orders of magnitude but has no effect on Km of this reaction. These facts point out that cytidine 5'-phosphate being adsorbed on the corresponding area of the donor site leads to the conversion of low-productive complex [ribosome + minimal donor substrate + acceptor substrate] into high-productive complex [ribosome + minimal donor substrate + acceptor substrate + cytidine 5'-phosphate].

  19. Method of forming through substrate vias (TSVs) and singulating and releasing die having the TSVs from a mechanical support substrate

    SciTech Connect

    Okandan, Murat; Nielson, Gregory N

    2014-12-09

    Accessing a workpiece object in semiconductor processing is disclosed. The workpiece object includes a mechanical support substrate, a release layer over the mechanical support substrate, and an integrated circuit substrate coupled over the release layer. The integrated circuit substrate includes a device layer having semiconductor devices. The method also includes etching through-substrate via (TSV) openings through the integrated circuit substrate that have buried ends at or within the release layer including using the release layer as an etch stop. TSVs are formed by introducing one or more conductive materials into the TSV openings. A die singulation trench is etched at least substantially through the integrated circuit substrate around a perimeter of an integrated circuit die. The integrated circuit die is at least substantially released from the mechanical support substrate.

  20. Universal Common Communication Substrate (UCCS) Specification; Universal Common Communication Substrate (UCCS) Implementation

    SciTech Connect

    2014-08-22

    Universal Common Communication Substrate (UCCS) is a low-level communication substrate that exposes high-performance communication primitives, while providing network interoperability. It is intended to support multiple upper layer protocol (ULPs) or programming models including SHMEM,UPC,Titanium,Co-Array Fortran,Global Arrays,MPI,GASNet, and File I/O. it provides various communication operations including one-sided and two-sided point-to-point, collectives, and remote atomic operations. In addition to operations for ULPs, it provides an out-of-band communication channel required typically required to wire-up communication libraries.

  1. An Efficient and Accurate Method of Estimating Substrate Noise Coupling in Heavily Doped Substrates

    DTIC Science & Technology

    2005-08-24

    αij values obtained from the original contact sizes. The αij calculated using the model is the same for both the cases. The error from this model is...substrate resistances in large circuits,” in Proc. European Design and Test Conference, March 1996, pp. 560-565. [5] E. Charbon , R. Gharpurey, P. Miliozzi...and E. Charbon , “Substrate coupling: modeling, simulation and design perspectives,” in Proc. of Quality Electronic Design, March 2004, pp. 283-290. [8

  2. Periodic nanostructures for SERS-active substrate

    NASA Astrophysics Data System (ADS)

    Zou, Wenlong; Cai, Zhijian; Wu, Jianhong

    2015-08-01

    Raman spectroscopy has become a very important tool in many fields, including chemistry, material, environmental protecting and etc. While Raman scattering is a weak process, it is often hampered in background noise. Since surface enhanced Raman scattering (SERS) was observed for the first time in 1974, surface enhanced Raman spectroscopy has developed more and more rapidly. Periodic nanostructures have the advantage of reliable and reproducible Raman signal relative to the irregular nanostructures. In this paper, holographic gratings coated by metal are proposed to fabricate SERS-active substrate. The excitation light excite on the gratings with proper grating constant that will lead to plasmon resonant phenomena, which enhance local electric field for Raman scattering. The electric field enhancement of sinusoidal, rectangular and triangular gratings is simulated using a commercially available software finite-difference-time-domain (FDTD). Period, groove depth, duty cycle and coated metal thickness of gratings affecting the electric field enhancement are also discussed. The optimum grating structure for SERS-active substrate is obtained in theory.

  3. Droplet evaporation on a soluble substrate

    NASA Astrophysics Data System (ADS)

    Mailleur, Alexandra; Pirat, Christophe; Colombani, Jean; CNES Collaboration

    2015-11-01

    Stains left by evaporated droplets are ubiquitous in everyday life as well as in industrial processes. Whatever the composition of the evaporating liquid (colloidal suspensions, biological fluids...), the stains are mostly constituted by a deposit at the periphery of the dried drop, similar to a coffee stain (Deegan, 1997). All these studies have been carried with non-reacting solids. In this presentation, we focus on the behavior of a pure-water droplet evaporating on a soluble substrate which is more complex, since three phenomena are strongly interacting: the dissolution of the substrate, the diffusion/convection of the dissolved species into the drop and the evaporation of the liquid. NaCl and KCl single crystals have been chosen for this experimental study as they are fast-dissolving solids. We have observed that the dissolution induces a pinning of the triple line from the beginning of the evaporation, leading to a decrease of the contact angle in time. At the end of the evaporation, a peripheral deposit is always formed, proof of an outward flow inside the drop (coffee-ring effect). The authors would like to thank the CNES for the financial support.

  4. Coiling of elastic rods on rigid substrates

    PubMed Central

    Jawed, Mohammad K.; Da, Fang; Joo, Jungseock; Grinspun, Eitan; Reis, Pedro M.

    2014-01-01

    We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study. PMID:25267649

  5. Recognition memory: material, processes, and substrates.

    PubMed

    Brown, Malcolm W; Warburton, E Clea; Aggleton, John P

    2010-11-01

    The proposal that a system centering on the perirhinal cortex is responsible for familiarity discrimination, particularly for single items, whereas a system centering on the hippocampus is responsible for recollective and more complex associational aspects of recognition memory is reviewed in the light of recent findings. In particular, the proposal is reviewed in relation to recent animal work with rats and results from human clinical studies. Notably, progress has been made in determining potential neural memory substrate mechanisms within the perirhinal cortex in rats. Recent findings have emphasized the importance of specifying the type of material, the type of test, and the strategy used by subjects to solve recognition memory tests if substrates are to be accurately inferred. It is to be expected that the default condition is that both the hippocampal and perirhinal systems will contribute to recognition memory performance. Indeed, rat lesion experiments provide examples of where cooperation between both systems is essential. Nevertheless, there remain examples of the independent operation of the hippocampal and perirhinal systems. Overall, it is concluded that most, though not all, of the recent findings are in support of the proposal. However, there is also evidence that the systems involved in recognition memory need to include structures outside the medial temporal lobe: there are significant but as yet only partially defined roles for the prefrontal cortex and sensory association cortices in recognition memory processes. © 2010 Wiley-Liss, Inc.

  6. Thiols as myeloperoxidase-oxidase substrates.

    PubMed Central

    Svensson, B E

    1988-01-01

    Nine low-Mr thiols were compared with regard to their ability to function as myeloperoxidase-oxidase substrates under conditions where no auto-oxidation of the thiols could be observed. The methyl and ethyl esters of cysteine were found to be about twice as active as cysteamine at pH 7.0, in terms of increased O2 consumption. Cysteine itself was poorly active, whereas glutathione, N-acetylcysteine and penicillamine were completely inactive as myeloperoxidase-oxidase substrates under these conditions. The structure-activity relationships indicated that both a free thiol and free amino group were required for peroxidase-oxidase activity, and also that a free carboxy group abolished activity. In analogy with cysteamine, the activities of both cysteine esters were inhibited by superoxide dismutase (less than 5 micrograms/ml) and by catalase and not by the hydroxyl-radical scavenger mannitol. In contrast with cysteamine, the activities of both cysteine esters were stimulated more than 2-fold by high concentrations (greater than 5 micrograms/ml) of superoxide dismutase. The activities of both cysteine esters exhibited broad pH optima at pH 7. A mechanism for the myeloperoxidase-oxidase oxidation of the cysteine esters is proposed, which is partly different from that previously proposed for cysteamine. PMID:2845919

  7. Efficient thermophotovoltaic solar cells on bent substrates

    NASA Astrophysics Data System (ADS)

    Shmavonyan, Gagik; Zadoyan, Ovsanna

    2013-04-01

    Thermophotovoltaic devices show promise as a method of reclaiming waste industrial heat and may provide a competitive and quiet low output heat conversion power supply for remote rural areas. GaSb based devices are well matched to a 1500-2000^oC blackbody emission temperature as well as to the solar spectrum when paired with GaAs. The growth of GaSb on GaAs proceeds via the Stranski-Krastanow mechanism, resulting in rectangular islands of GaSb with their edges orientated along the 110directions. The size of the islands is dependent on the growth temperature with smaller islands being produced for lower temperatures. The rectification behavior of p-GaSb/n-GaAs heterojunctions is also strongly dependent on the growth temperature. Possible mechanisms for the rectification at low temperature include more rapid turnover of interface dislocations and a corresponding reduction in carrier generation/recombination processes or passivation of defect centres by greater incorporation of impurities such as hydrogen. By optimizing the growth conditions, efficient p-GaSb/n-GaAs thermophotovoltaic devices have been produced. A series of GaSb and GaAs epilayers grown onto substrates has been used to investigate the effect of bent substrate on external quantum efficiency and spectral response.

  8. Substrate utilization during exercise in active people.

    PubMed

    Coyle, E F

    1995-04-01

    When people walk at low intensity after fasting, the energy needed is provided mostly by oxidation of plasma fatty acids. As exercise intensity increases (eg, to moderate running), plasma fatty acid turnover does not increase and the additional energy is obtained by utilization of muscle glycogen, blood glucose, and intramuscular triglyceride. Further increases in exercise intensity are fueled mostly by increases in muscle glycogen utilization with some additional increase in blood glucose oxidation. Muscle glycogen and blood glucose contribute equally to carbohydrate energy production over 2-3 h of moderate-intensity exercise; fatigue develops when these substrates are depleted. Active people can deplete muscle glycogen with 30-60 min of high intensity, intermittent exercise. When the ingestion of dietary carbohydrate is optimal, it is possible to resynthesize muscle glycogen to high concentrations in approximately 24 h, which is the major factor in recovery of exercise tolerance. However, this requires that a 70-kg person eat at least 50 g carbohydrate per every 2 h, beginning soon after exercise, and ingest 500-600 g in 24 h (ie; approximately 7-9 g/kg body wt). Carbohydrate foods eliciting high glycemic and insulinemic responses promote more rapid glycogen resynthesis than do foods eliciting lower glycemic responses. Therefore, foods ingested for energy before, during, or after exercise should be classified according to their glycemic index. Although carbohydrate ingestion before and during exercise adds exogenous substrate to the body, it usually attenuates plasma fatty acid mobilization and oxidation.

  9. Adhesion of D. discoideum on Hydrophobic Substrate

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Ploscariu, Nicoleta

    2015-03-01

    Adhesion by amoeboid cells, such as D. discoideum, is poorly understood but critical for other behaviors such as phagocytosis and migration. Furthermore, both leucocytes and breast cancer cells employ the amoeboid mode of movement at various points in their life-cycles. Hence, improved knowledge of amoeboid adhesion may lead to be new strategies for controlling other important cellular processes. This study regards adhesion by D. discoideum on silanized glass substrates. Reflection interference contrast microscopy is used in conjunction with other methods to determine the contact angle, cell-medium interfacial energy, and adhesion energy of these cells. The contact angle of individual cells settling under gravity onto a substrate is observed to increase as the size of the contact patch increases. This behavior occurs on slower time-scales than expected for the settling of inert vesicles. The implications of this observation on the nature of the underlying forces will be discussed. This work was supported in part by NSF Grant PHY-646966.

  10. The neural substrate of gesture recognition.

    PubMed

    Villarreal, Mirta; Fridman, Esteban A; Amengual, Alejandra; Falasco, German; Gerschcovich, Eliana Roldan; Gerscovich, Eliana Roldan; Ulloa, Erlinda R; Leiguarda, Ramon C

    2008-01-01

    Previous studies have linked action recognition with a particular pool of neurons located in the ventral premotor cortex, the posterior parietal cortex and the superior temporal sulcus (the mirror neuron system). However, it is still unclear if transitive and intransitive gestures share the same neural substrates during action-recognition processes. In the present study, we used event-related functional magnetic resonance imaging (fMRI) to assess the cortical areas active during recognition of pantomimed transitive actions, intransitive gestures, and meaningless control actions. Perception of all types of gestures engaged the right pre-supplementary motor area (pre-SMA), and bilaterally in the posterior superior temporal cortex, the posterior parietal cortex, occipitotemporal regions and visual cortices. Activation of the posterior superior temporal sulcus/superior temporal gyrus region was found in both hemispheres during recognition of transitive and intransitive gestures, and in the right hemisphere during the control condition; the middle temporal gyrus showed activation in the left hemisphere when subjects recognized transitive and intransitive gestures; activation of the left inferior parietal lobe and intraparietal sulcus (IPS) was mainly observed in the left hemisphere during recognition of the three conditions. The most striking finding was the greater activation of the left inferior frontal gyrus (IFG) during recognition of intransitive actions. Results show that a similar neural substrate, albeit, with a distinct engagement underlies the cognitive processing of transitive and intransitive gestures recognition. These findings suggest that selective disruptions in these circuits may lead to distinct clinical deficits.

  11. Interaction of Drops on a Soft Substrate

    NASA Astrophysics Data System (ADS)

    Lubbers, Luuk A.; Weijs, Joost H.; Das, Siddhartha; Botto, Lorenzo; Andreotti, Bruno; Snoeijer, Jacco H.

    2013-11-01

    A sessile drop can elastically deform a substrate by the action of capillary forces. The typical size of the deformation is given by the ratio of surface tension and the elastic modulus, γ / E , which can reach up to 10-100 microns for soft elastomers. In this talk we theoretically show that the contact angles of drops on such a surface exhibit two transitions when increasing γ / E : (i) the microsocopic geometry of the contact line first develops a Neumann-like cusp when γ / E is of the order of few nanometers, (ii) the macroscopic angle of the drop is altered only when γ / E reaches the size of the drop. Using the same framework we then show that two neighboring drops exhibit an effective interaction, mediated by the deformation of the elastic medium. This is in analogy to the well-known Cheerios effect, where small particles at a liquid interface attract eachother due to the meniscus deformations. Here we reveal the nature of drop-drop interactions on a soft substrate by combining numerical and analytical calculations.

  12. Neural substrates of sublexical processing for spelling.

    PubMed

    DeMarco, Andrew T; Wilson, Stephen M; Rising, Kindle; Rapcsak, Steven Z; Beeson, Pélagie M

    2017-01-01

    We used fMRI to examine the neural substrates of sublexical phoneme-grapheme conversion during spelling in a group of healthy young adults. Participants performed a writing-to-dictation task involving irregular words (e.g., choir), plausible nonwords (e.g., kroid), and a control task of drawing familiar geometric shapes (e.g., squares). Written production of both irregular words and nonwords engaged a left-hemisphere perisylvian network associated with reading/spelling and phonological processing skills. Effects of lexicality, manifested by increased activation during nonword relative to irregular word spelling, were noted in anterior perisylvian regions (posterior inferior frontal gyrus/operculum/precentral gyrus/insula), and in left ventral occipito-temporal cortex. In addition to enhanced neural responses within domain-specific components of the language network, the increased cognitive demands associated with spelling nonwords engaged domain-general frontoparietal cortical networks involved in selective attention and executive control. These results elucidate the neural substrates of sublexical processing during written language production and complement lesion-deficit correlation studies of phonological agraphia.

  13. Patterned melt electrospun substrates for tissue engineering.

    PubMed

    Dalton, Paul D; Joergensen, Nanna T; Groll, Juergen; Moeller, Martin

    2008-09-01

    Tissue engineering scaffolds can be built with patterning techniques that allow discrete placement of structures. In this study, electrospun fibres are collected in focused spots; the patterning and drawing of a cell adhesive scaffold is shown. Blends of biodegradable poly(ethylene glycol)-block-poly(epsilon-caprolactone) (PEG-b-PCL) and PCL were melt electrospun onto glass collectors, and the optimal electrospinning parameters determined. The quality of the fibre was largely influenced by the flow rate of the melt to the spinneret; however, this can be adjusted with the voltage. A collection distance between 3 cm and 5 cm was optimal, and at 10 cm the fibres became unfocused in their deposition although the diameter remained similar (0.96 +/- 0.19 microm). Aligned lines of electrospun fibres 200-400 microm in width could be applied onto the slide with an x-y stage, continuously and discretely. Lines of electrospun fibres could be applied on top of one another and were very uniform in diameter. Fibroblasts adhered primarily in the fibre region, due to the poor cell adhesion to the PEG substrate. Improvements in depositing hydrophilic electrospun fibres that wet and adhere to in vitro substrates and the use of stage automation for the writing interface could provide scaffold-building devices suitable for tissue engineering applications.

  14. Bulk metallic glass coating of polymer substrates

    NASA Astrophysics Data System (ADS)

    Soinila, Erno; Sharma, Parmanand; Heino, Markku; Pischow, Kaj; Inoue, Akihisa; Hänninen, Hannu

    2009-01-01

    Bulk Metallic Glass (BMG) alloy with the composition of Zr55Cu30Al10Ni5 was deposited by sputtering as thin films on several different engineering polymers and polymer composites. Polycarbonate, polymethyl methacrylate, polyamide 12, polyarylamide (50GF=50 % glass fibers), polyphenylene sulfide (30GF) and polybutylene terephthalate (30GF) were used as substrates. The microstructure of the deposited BMG coatings was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of XRD and SEM studies were consistent with amorphous microstructure. Elemental compositions of the coatings were verified by energy dispersive spectroscopy (EDS). Mechanical properties of the coatings were compared to copper mould cast BMG using nano- indentation tests with similar results. According to the cross-cut tape tests good adhesion was achieved between the studied BMG alloy and all other polymer substrates except polycarbonate. Nano-indentation results showed similar mechanical properties for coating and cast BMG. The results of this study look promising as they open new opportunities for BMG- polymer composite applications.

  15. Substrates and Inhibitors of SAMHD1

    PubMed Central

    Tao, Sijia; Amiralaei, Sheida; Liu, Peng; Lu, Xiao; Goetze, Russell W.; Zhou, Longhu; Nettles, James H.; Schinazi, Raymond F.; Kim, Baek

    2017-01-01

    SAMHD1 hydrolyzes 2'-deoxynucleoside-5'-triphosphates (dNTPs) into 2'-deoxynucleosides and inorganic triphosphate products. In this paper, we evaluated the impact of 2' sugar moiety substitution for different nucleotides on being substrates for SAMHD1 and mechanisms of actions for the results. We found that dNTPs ((2'R)-2'-H) are only permissive in the catalytic site of SAMHD1 due to L150 exclusion of (2'R)-2'-F and (2'R)-2'-OH nucleotides. However, arabinose ((2'S)-2'-OH) nucleoside-5'-triphosphates analogs are permissive to bind in the catalytic site and be hydrolyzed by SAMHD1. Moreover, when the (2'S)-2' sugar moiety is increased to a (2'S)-2'-methyl as with the SMDU-TP analog, we detect inhibition of SAMHD1’s dNTPase activity. Our computational modeling suggests that (2'S)-2'-methyl sugar moiety clashing with the Y374 of SAMHD1. We speculate that SMDU-TP mechanism of action requires that the analog first docks in the catalytic pocket of SAMHD1 but prevents the A351-V378 helix conformational change from being completed, which is needed before hydrolysis can occur. Collectively we have identified stereoselective 2' substitutions that reveal nucleotide substrate specificity for SAMHD1, and a novel inhibitory mechanism for the dNTPase activity of SAMHD1. Importantly, our data is beneficial for understanding if FDA-approved antiviral and anticancer nucleosides are hydrolyzed by SAMHD1 in vivo. PMID:28046007

  16. Agaricus blazei production on non-composted substrates based on sunflower seed hulls and spent oyster mushroom substrate.

    PubMed

    González Matute, R; Figlas, D; Curvetto, N

    2011-06-01

    Agaricus blazei Murrill is usually cultivated using the same biphasic composting method employed for A. bisporus. Because cultivation of A. blazei on traditional A. bisporus composts poses some disadvantages, non-composted substrates were studied for A. blazei cultivation. Mycelial growth rate and productive performance of A. blazei were evaluated on substrates containing sunflower seed hulls, Pleurotus spp. spent mushroom substrate, or their combination, in the absence or in the presence of different supplements (vermicompost, peat or brewery residues). Substrates were prepared by initially soaking them and then they were sterilized (1 atm for 120 min). In addition, each substrate's degradation was measured after cultivation by obtaining the lignin, cellulose, hemicellulose, organic matter, total fiber, ash, carbon and nitrogen contents before spawn-run and at the end of two flushes of A. blazei. The cultivation of A. blazei on non-composted substrates is possible and with a low rate of contamination when using the spent mushroom substrate as the main component or combined 50:50 with sunflower seed hulls. In addition, the best yields were obtained on those substrates containing spent Pleurotus mushroom substrate with supplements and those mixtures with sunflower seed hulls and vermicompost. These yields were similar to those reported on composted substrates. Substrate changes in composition measured at the end of two flushes indicate that the lignin-hemicellulose fraction was preferentially used and that the substrates exhibiting the best yield showed greater biodegradation of lignin-hemicellulose fraction than the others did.

  17. Mean field theory studies of surface reactions on disordered substrates

    NASA Astrophysics Data System (ADS)

    Cortés, Joaquín.; Narváez, Ana; Puschmann, Heinrich; Valencia, Eliana

    2003-03-01

    A mean field theory (MFT) in the site and pair approximations of a surface reaction system on a disordered substrate showing geometric heterogeneity is proposed, characterizing the substrate completely through the set { qi} of probabilities that a surface site has i neighbours that belong to the substrate in the model. The MFT results allow the interpretation of the Monte Carlo (MC) simulations carried out for the ZGB algorithm at instantaneous and finite rates over a series heterogeneous substrates corresponding to percolation clusters. The change in the character of the irreversible phase transitions (IPT) with the degree of disorder or branching of the substrate and its theoretical interpretation are analyzed.

  18. Effect of substrate competition in kinetic models of metabolic networks.

    PubMed

    Schäuble, Sascha; Stavrum, Anne Kristin; Puntervoll, Pål; Schuster, Stefan; Heiland, Ines

    2013-09-02

    Substrate competition can be found in many types of biological processes, ranging from gene expression to signal transduction and metabolic pathways. Although several experimental and in silico studies have shown the impact of substrate competition on these processes, it is still often neglected, especially in modelling approaches. Using toy models that exemplify different metabolic pathway scenarios, we show that substrate competition can influence the dynamics and the steady state concentrations of a metabolic pathway. We have additionally derived rate laws for substrate competition in reversible reactions and summarise existing rate laws for substrate competition in irreversible reactions.

  19. Method for removing semiconductor layers from salt substrates

    DOEpatents

    Shuskus, Alexander J.; Cowher, Melvyn E.

    1985-08-27

    A method is described for removing a CVD semiconductor layer from an alkali halide salt substrate following the deposition of the semiconductor layer. The semiconductor-substrate combination is supported on a material such as tungsten which is readily wet by the molten alkali halide. The temperature of the semiconductor-substrate combination is raised to a temperature greater than the melting temperature of the substrate but less than the temperature of the semiconductor and the substrate is melted and removed from the semiconductor by capillary action of the wettable support.

  20. Assay for Lipolytic and Proteolytic Activity Using Marine Substrates

    PubMed Central

    Tom, Raymond A.; Crisan, Eli V.

    1975-01-01

    Nondestructive assay procedures for determining microbial lipolytic and proteolytic activity on marine substrates were developed and tested with 287 isolates of bacteria, filamentous fungi, and yeasts. A definite substrate specificity was noted when the enzymatic activities on marine and nonmarine substrates was compared. Of 170 lipolytic isolates, 14 were only active on menhaden oil, 11 could hydrolyze menhaden oil and Tween 80 and/or tributyrin, and 145 isolates could only hydrolyze one or both of the nonmarine lipids. Of the 198 proteolytic isolates, 10 were specific for codfish extract, 152 were active against the marine substrate plus casein and/or gelatin, and 36 were specific for nonmarine substrates. PMID:1167775

  1. Dynamics of a monolayer of microspheres on an elastic substrate

    NASA Astrophysics Data System (ADS)

    Wallen, S. P.; Maznev, A. A.; Boechler, N.

    2015-11-01

    We present a model for wave propagation in a monolayer of spheres on an elastic substrate. The model, which considers sagittally polarized waves, includes: horizontal, vertical, and rotational degrees of freedom; normal and shear coupling between the spheres and substrate, as well as between adjacent spheres; and the effects of wave propagation in the elastic substrate. For a monolayer of interacting spheres, we find three contact resonances, whose frequencies are given by simple closed-form expressions. For a monolayer of isolated spheres, only two resonances are present. The contact resonances couple to surface acoustic waves in the substrate, leading to mode hybridization and "avoided crossing" phenomena. We present dispersion curves for a monolayer of silica microspheres on a silica substrate, assuming adhesive Hertzian interactions, and compare calculations using an effective medium approximation (including elasticity of the substrate) to a discrete model of a monolayer on a rigid substrate. While the effective medium model does not describe discrete lattice effects occurring at short wavelengths, we find that it is well suited for describing the interaction between the monolayer and substrate in the long wavelength limit. We suggest that a complete picture of the dynamics of a monolayer adhered to an elastic substrate can be found by combining the dispersion curves generated with the effective medium model for the elastic substrate and the discrete model for the rigid substrate. This model is potentially scalable for use with nano- to macroscale systems, and offers the prospect of experimentally extracting contact stiffnesses from measurements of acoustic dispersion.

  2. Nemesia Root Hair Response to Paper Pulp Substrate for Micropropagation

    PubMed Central

    Labrousse, Pascal; Delmail, David; Decou, Raphaël; Carlué, Michel; Lhernould, Sabine; Krausz, Pierre

    2012-01-01

    Agar substrates for in vitro culture are well adapted to plant micropropagation, but not to plant rooting and acclimatization. Conversely, paper-pulp-based substrates appear as potentially well adapted for in vitro culture and functional root production. To reinforce this hypothesis, this study compares in vitro development of nemesia on several substrates. Strong differences between nemesia roots growing in agar or in paper-pulp substrates were evidenced through scanning electron microscopy. Roots developed in agar have shorter hairs, larger rhizodermal cells, and less organized root caps than those growing on paper pulp. In conclusion, it should be noted that in this study, in vitro microporous substrates such as paper pulp lead to the production of similar root hairs to those found in greenhouse peat substrates. Consequently, if agar could be used for micropropagation, rooting, and plant acclimatization, enhancement could be achieved if rooting stage was performed on micro-porous substrates such as paper pulp. PMID:22312323

  3. Method of Making Thermally Stable, Piezoelectric and Proelectric Polymeric Substrates

    NASA Technical Reports Server (NTRS)

    Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

    1999-01-01

    A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium: applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

  4. Method and apparatus for coating substrates using a laser

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I. (Inventor)

    1984-01-01

    Metal substrates, preferably of titanium and titanium alloys, are coated by alloying or forming TiN on a substrate surface. A laser beam strikes the surface of a moving substrate in the presence of purified nitrogen gas. A small area of the substrate surface is quickly heated without melting. This heated area reacts with the nitrogen to form a solid solution. The alloying or formation of TiN occurs by diffusion of nitrogen into the titanium. Only the surface layer of the substrate is heated because of the high power density of the laser beam and short exposure time. The bulk of the substrate is not affected, and melting of the substrate is avoided because it would be detrimental.

  5. Substrate heterogeneity and regeneration of a swamp tree, Nyssa aquatica

    SciTech Connect

    Huenneke, L.F.; Sharitz, R.R. )

    1990-03-01

    We investigated physical characteristics of several substrate types in a South Carolina riverine swamp forest, and the effect of those characteristics upon germination and seedling growth of the dominant swamp tree, Nyssa aquatica (water tupelo). Substrates were categorized as emergent (surfaces of trees, living cypress knees, stumps, or logs), protected (submerged sediment adjacent to an emergent object), or open (sediment > 50 cm from any emergent object and fully submerged during the growing season). Water tupelo seeds germinated best (> 25% in 16 days) on emergent substrates, but seed predation was extremely high on these same substrates. Substrate types differed significant in permanence and in rates of sediment loss or deposition. Growth rates of transplanted seedlings did not differ among substrate types. The result suggest that mortality due to erosional scour or impermanent rooting zones, superimposed on germination patterns, is responsible for the observed nonrandom distribution of woody plant seedlings among substrate types in the swamp forest.

  6. Fibroblast motility on substrates with different rigidities: modeling approach

    NASA Astrophysics Data System (ADS)

    Gracheva, Maria; Dokukina, Irina

    2009-03-01

    We develop a discrete model for cell locomotion on substrates with different rigidities and simulate experiments described in Lo, Wang, Dembo, Wang (2000) ``Cell movement is guided by the rigidity of the substrate'', Biophys. J. 79: 144-152. In these experiments fibroblasts were planted on a substrate with a step rigidity and showed preference for locomotion over stiffer side of the substrate when approaches the boundary between the soft and the stiff sides of the substrate. The model reproduces experimentally observed behavior of fibroblasts. In particular, we are able to show with our model how cell characteristics (such as cell length, shape, area and speed) change during cell crawling through the ``soft-stiff'' substrate boundary. Also, our model suggests the temporary increase of both cell speed and area in that very moment when cell leaves soft side of substrate.

  7. Cloning a neutral protease of Clostridium histolyticum, determining its substrate specificity, and designing a specific substrate.

    PubMed

    Maeda, Hiroshi; Nakagawa, Kanako; Murayama, Kazutaka; Goto, Masafumi; Watanabe, Kimiko; Takeuchi, Michio; Yamagata, Youhei

    2015-12-01

    Islet transplantation is a prospective treatment for restoring normoglycemia in patients with type 1 diabetes. Islet isolation from pancreases by decomposition with proteolytic enzymes is necessary for transplantation. Two collagenases, collagenase class I (ColG) and collagenase class II (ColH), from Clostridium histolyticum have been used for islet isolation. Neutral proteases have been added to the collagenases for human islet isolation. A neutral protease from C. histolyticum (NP) and thermolysin from Bacillus thermoproteolyicus has been used for the purpose. Thermolysin is an extensively studied enzyme, but NP is not well known. We therefore cloned the gene encoding NP and constructed a Bacillus subtilis overexpression strain. The expressed enzyme was purified, and its substrate specificity was examined. We observed that the substrate specificity of NP was higher than that of thermolysin, and that the protein digestion activities of NP, as determined by colorimetric methods, were lower than those of thermolysin. It seems that decomposition using NP does not negatively affect islets during islet preparation from pancreases. Furthermore, we designed a novel substrate that allows the measurement of NP activity specifically in the enzyme mixture for islet preparation and the culture broth of C. histolyticum. The activity of NP can also be monitored during islet isolation. We hope the purified enzyme and this specific substrate contribute to the optimization of islet isolation from pancreases and that it leads to the success of islet transplantation and the improvement of the quality of life (QOL) for diabetic patients.

  8. Anodic Bonding between LTCC Substrate and Si Substrate with Electrical Connections

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Sakae; Tanaka, Shuji; Esashi, Masayoshi

    This paper describes metal-metal electrical connection simultaneously established with anodic bonding between a LTCC (low temperature cofired ceramic) substrate and a Si substrate. Metal pads are composed of Sn on Cu. Sn melts during anodic bonding, absorbing the height margin of the metal pads to ensure good contact between the LTCC substrate and the Si substrate. This study first investigated formic acid vapor treatment before anodic bonding to remove an oxide layer on the Sn surface. The removal of the oxide layer proceeds at a process temperature of 150°C or higher. By the treatment at 250°C, the surface of the Sn layer is smoothed due to reflow effect, but the multilayer structure of the metal pads does not significantly change after 5 min treatment. The bonded metal pad is almost uniform in both structure and composition throughout its thickness. The composition of the bonded metal pads is approximately Sn : Cu = 1 : 1 in atomic ratio, and might have a remelting temperature of ca. 415°C, which is much higher than a reflow temperature in device mounting process.

  9. [Influence of substrate concentration on PHA production using fermented sugar cane as substrate].

    PubMed

    Chen, Zhi-Qiang; Deng, Yi; Huang, Long; Wen, Qin-Xue; Guo, Zi-Rui

    2013-06-01

    PHA was a kind of biodegradable polymer produced by mixed microorganisms. In recent years, 3-stage PHA synthesis process (including substrate hydrolysis, culture selection, and PHA synthesis) was commonly used for PHA production. In this kind of process, culture selection is the key stage, which directly affects the PHA production efficiency. In order to deal with sludge bulking occurred in the culture selection system, this paper analyzes the influence of substrate concentration on culture selection efficiency as well as operation stability. Under different influent substrate concentrations of 560 mg x L(-1), 1 120 mg x L(-1) and 1 680 mg x L(-1), we confirmed that influent substrate concentration (COD) of 1 120 mg x L(-1) is the most suitable parameter for the bacteria enriching process after a long period of time under short SRT. After 94 days of cultivation, we achieved 50% of PHA content, 0.7145 COD/COD of PHA conversion rate and 0.191 2 mg x (mg x h)(-1) of specific PHA storage rate at the end of batch tests with nutrient starvation. The study also confirmed that glycogen level in cells has a close relationship with its PHA synthesis ability, which shows its potential to predict the enrichment efficiency.

  10. Automatic classification of blank substrate defects

    NASA Astrophysics Data System (ADS)

    Boettiger, Tom; Buck, Peter; Paninjath, Sankaranarayanan; Pereira, Mark; Ronald, Rob; Rost, Dan; Samir, Bhamidipati

    2014-10-01

    Mask preparation stages are crucial in mask manufacturing, since this mask is to later act as a template for considerable number of dies on wafer. Defects on the initial blank substrate, and subsequent cleaned and coated substrates, can have a profound impact on the usability of the finished mask. This emphasizes the need for early and accurate identification of blank substrate defects and the risk they pose to the patterned reticle. While Automatic Defect Classification (ADC) is a well-developed technology for inspection and analysis of defects on patterned wafers and masks in the semiconductors industry, ADC for mask blanks is still in the early stages of adoption and development. Calibre ADC is a powerful analysis tool for fast, accurate, consistent and automatic classification of defects on mask blanks. Accurate, automated classification of mask blanks leads to better usability of blanks by enabling defect avoidance technologies during mask writing. Detailed information on blank defects can help to select appropriate job-decks to be written on the mask by defect avoidance tools [1][4][5]. Smart algorithms separate critical defects from the potentially large number of non-critical defects or false defects detected at various stages during mask blank preparation. Mechanisms used by Calibre ADC to identify and characterize defects include defect location and size, signal polarity (dark, bright) in both transmitted and reflected review images, distinguishing defect signals from background noise in defect images. The Calibre ADC engine then uses a decision tree to translate this information into a defect classification code. Using this automated process improves classification accuracy, repeatability and speed, while avoiding the subjectivity of human judgment compared to the alternative of manual defect classification by trained personnel [2]. This paper focuses on the results from the evaluation of Automatic Defect Classification (ADC) product at MP Mask

  11. Screening of thermophilic anaerobic bacteria for solid substrate cultivation on lignocellulosic substrates.

    PubMed

    Chinn, Mari S; Nokes, Sue E; Strobel, Herbert J

    2006-01-01

    Interest in solid substrate cultivation (SSC) techniques is gaining for biochemical production from renewable resources; however, heat and mass transfer problems may limit application of this technique. The use of anaerobic thermophiles in SSC offers a unique solution to overcoming these challenges. The production potential of nine thermophilic anaerobic bacteria was examined on corn stover, sugar cane bagasse, paper pulp sludge, and wheat bran in submerged liquid cultivation (SmC) and SSC. Production of acetate, ethanol, and lactate was measured over a 10 day period, and total product concentrations were used to compare the performance of different organism-substrate combinations using the two cultivation methods. Overall microbial activity in SmC and SSC was dependent on the organism and growth substrate. Clostridium thermocellum strains JW20, LQRI, and 27405 performed significantly better in SSC when grown on sugar cane bagasse and paper pulp sludge, producing at least 70 and 170 mM of total products, respectively. Growth of C. thermocellum strains in SSC on paper pulp sludge proved to be most favorable, generating at least twice the concentration of total products produced in SmC (p-value < 0.05). Clostridium thermolacticum TC21 demonstrated growth on all substrates producing 30-80 and 60-116 mM of total product in SmC and SSC, respectively. Bacterial species with optimal growth temperatures of 70 degrees C grew best on wheat bran in SmC, producing total product concentrations of 45-75 mM. For some of the organism-substrate combinations total end product concentrations in SSC exceeded those in SmC, indicating that SSC may be a promising alternative for microbial activity and value-added biochemical production.

  12. Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates

    PubMed Central

    Tang, Jun; Guo, Hao; Zhao, Miaomiao; Yang, Jiangtao; Tsoukalas, Dimitris; Zhang, Binzhen; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2015-01-01

    This paper demonstrates a fabrication technology of Ag wrinkled electrodes with application in highly stretchable wireless sensors. Ag wrinkled thin films that were formed by vacuum deposition on top of pre-strained and relaxed polydimethylsiloxane (PDMS) substrates which have been treated using an O2 plasma and a surface chemical functionalization process can reach a strain limit up to 200%, while surface adhesion area can reach 95%. The electrical characteristics of components such as resistors, inductors and capacitors made from such Ag conductors have remained stable under stretching exhibiting low temperature and humidity coefficients. This technology was then demonstrated for wireless wearable electronics using compatible processing with established micro/nano fabrication technology. PMID:26585636

  13. The structural neural substrate of subjective happiness.

    PubMed

    Sato, Wataru; Kochiyama, Takanori; Uono, Shota; Kubota, Yasutaka; Sawada, Reiko; Yoshimura, Sayaka; Toichi, Motomi

    2015-11-20

    Happiness is a subjective experience that is an ultimate goal for humans. Psychological studies have shown that subjective happiness can be measured reliably and consists of emotional and cognitive components. However, the neural substrates of subjective happiness remain unclear. To investigate this issue, we used structural magnetic resonance imaging and questionnaires that assessed subjective happiness, the intensity of positive and negative emotional experiences, and purpose in life. We found a positive relationship between the subjective happiness score and gray matter volume in the right precuneus. Moreover, the same region showed an association with the combined positive and negative emotional intensity and purpose in life scores. Our findings suggest that the precuneus mediates subjective happiness by integrating the emotional and cognitive components of happiness.

  14. Substrate cleaning for integrated optical waveguides.

    PubMed

    Brandt, G B; Supertzi, E P; Henningsen, T

    1973-12-01

    Losses in integrated optical waveguides depend upon the homogeneity of the guiding layer. Successful production of acceptable guides by sputtering or solution deposition depends critically on the methods used to clean the substrate. Cleaning methods that produce films adequate for ordinary coatings have proved inadequate for integrated optical films. The extreme cleanliness required to produce low-loss waveguides can be achieved by a process described in this paper, which utilizes a precleaning step in an ultrasonically agitated detergent bath followed by careful rinsing in an ultrasonically agitated bath of heated, deionized, and filtered water. In addition to the cleaning method, we discuss the design of a cleaning station that combines the necessary apparatus in a portable unit.

  15. Dancing droplets: Chemical space, substrates, and control

    NASA Astrophysics Data System (ADS)

    Cira, Nate; Benusiglio, Adrien; Prakash, Manu

    2015-11-01

    Previously we showed that droplets of propylene glycol and water display remarkable properties when placed on clean glass due to an interplay between surface tension and evaporation. (Cira, Benusiglio, Prakash: Nature, 2015). We showed that these mechanisms apply to a range of two-component mixtures of miscible liquids where one component has both higher surface tension and higher vapor pressure on a variety of high energy surfaces. We now show how this rule can be cheated using a simple trick. We go on to demonstrate applications for cleaning, and show how this system works on substrates prepared only with sunlight. We finish by demonstrating active control of droplets, allowing access to a host of new possibilities.

  16. Somatosensory Substrates of Flight Control in Bats

    PubMed Central

    Marshall, Kara L.; Chadha, Mohit; deSouza, Laura A.; Sterbing-D’Angelo, Susanne J.; Moss, Cynthia F.; Lumpkin, Ellen A.

    2015-01-01

    Summary Flight maneuvers require rapid sensory integration to generate adaptive motor output. Bats achieve remarkable agility with modified forelimbs that serve as airfoils while retaining capacity for object manipulation. Wing sensory inputs provide behaviorally relevant information to guide flight; however, components of wing sensory-motor circuits have not been analyzed. Here, we elucidate the organization of wing innervation in an insectivore, the big brown bat, Eptesicus fuscus. We demonstrate that wing sensory innervation differs from other vertebrate forelimbs, revealing a peripheral basis for the atypical topographic organization reported for bat somatosensory nuclei. Furthermore, the wing is innervated by an unusual complement of sensory neurons poised to report airflow and touch. Finally, we report that cortical neurons encode tactile and airflow inputs with sparse activity patterns. Together, our findings identify neural substrates of somatosensation in the bat wing and imply that evolutionary pressures giving rise to mammalian flight led to unusual sensorimotor projections. PMID:25937277

  17. Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates.

    PubMed

    Tang, Jun; Guo, Hao; Zhao, Miaomiao; Yang, Jiangtao; Tsoukalas, Dimitris; Zhang, Binzhen; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2015-11-20

    This paper demonstrates a fabrication technology of Ag wrinkled electrodes with application in highly stretchable wireless sensors. Ag wrinkled thin films that were formed by vacuum deposition on top of pre-strained and relaxed polydimethylsiloxane (PDMS) substrates which have been treated using an O2 plasma and a surface chemical functionalization process can reach a strain limit up to 200%, while surface adhesion area can reach 95%. The electrical characteristics of components such as resistors, inductors and capacitors made from such Ag conductors have remained stable under stretching exhibiting low temperature and humidity coefficients. This technology was then demonstrated for wireless wearable electronics using compatible processing with established micro/nano fabrication technology.

  18. The structural neural substrate of subjective happiness

    PubMed Central

    Sato, Wataru; Kochiyama, Takanori; Uono, Shota; Kubota, Yasutaka; Sawada, Reiko; Yoshimura, Sayaka; Toichi, Motomi

    2015-01-01

    Happiness is a subjective experience that is an ultimate goal for humans. Psychological studies have shown that subjective happiness can be measured reliably and consists of emotional and cognitive components. However, the neural substrates of subjective happiness remain unclear. To investigate this issue, we used structural magnetic resonance imaging and questionnaires that assessed subjective happiness, the intensity of positive and negative emotional experiences, and purpose in life. We found a positive relationship between the subjective happiness score and gray matter volume in the right precuneus. Moreover, the same region showed an association with the combined positive and negative emotional intensity and purpose in life scores. Our findings suggest that the precuneus mediates subjective happiness by integrating the emotional and cognitive components of happiness. PMID:26586449

  19. Palladium on Plastic Substrates for Plasmonic Devices

    PubMed Central

    Zuppella, Paola; Pasqualotto, Elisabetta; Zuccon, Sara; Gerlin, Francesca; Corso, Alain Jody; Scaramuzza, Matteo; De Toni, Alessandro; Paccagnella, Alessandro; Pelizzo, Maria Guglielmina

    2015-01-01

    Innovative chips based on palladium thin films deposited on plastic substrates have been tested in the Kretschmann surface plasmon resonance (SPR) configuration. The new chips combine the advantages of a plastic support that is interesting and commercially appealing and the physical properties of palladium, showing inverted surface plasmon resonance (ISPR). The detection of DNA chains has been selected as the target of the experiment, since it can be applied to several medical early diagnostic tools, such as different biomarkers of cancers or cystic fibrosis. The results are encouraging for the use of palladium in SPR-based sensors of interest for both the advancement of biodevices and the development of hydrogen sensors. PMID:25585102

  20. Nitrite, a new substrate for nitrogenase

    SciTech Connect

    Vaughn, S.A.; Burgess, B.K. )

    1989-01-24

    The authors have examined the reactivity of the purified component proteins of Azotobacter vinelandii nitrogenase (Av1 and Av2) toward nitrate and nitrite. Nitrate has no effect on H{sub 2} evolution or C{sub 2}H{sub 2} reduction by nitrogenase and thus is neither a substrate nor an inhibitor. Nitrite dramatically inhibits H{sub 2} evolution. This inhibition has two components, one irreversible and one reversible upon addition of CO. The irreversible inhibition is due to nitrite inactivation of the Fe protein. The rate of this inactivation is greatly enhanced by addition of MgATP, suggesting the (4Fe-4S) cluster is the site of nitrite attack. The reversible inhibition does not represent an inhibition of electron flow but rather a diversion of electrons away from H{sub 2} evolution and into the six-electron reduction of nitrite to ammonia. Thus, nitrogenase functions as a nitrite reductase.

  1. Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates

    NASA Astrophysics Data System (ADS)

    Tang, Jun; Guo, Hao; Zhao, Miaomiao; Yang, Jiangtao; Tsoukalas, Dimitris; Zhang, Binzhen; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2015-11-01

    This paper demonstrates a fabrication technology of Ag wrinkled electrodes with application in highly stretchable wireless sensors. Ag wrinkled thin films that were formed by vacuum deposition on top of pre-strained and relaxed polydimethylsiloxane (PDMS) substrates which have been treated using an O2 plasma and a surface chemical functionalization process can reach a strain limit up to 200%, while surface adhesion area can reach 95%. The electrical characteristics of components such as resistors, inductors and capacitors made from such Ag conductors have remained stable under stretching exhibiting low temperature and humidity coefficients. This technology was then demonstrated for wireless wearable electronics using compatible processing with established micro/nano fabrication technology.

  2. Influence of substrate micropatterning on biofilm growth

    NASA Astrophysics Data System (ADS)

    Koehler, Stephan; Li, Yiwei; Liu, Bi-Feng Liu; Weitz, David

    2015-11-01

    We culture triple reporter Bacillus Subtilis biofilm on micropatterned agar substrates. We track the biofilm development in terms of size, thickness, shape, and phenotype expression. For a tiling composed of elevated rectangles, we observe the biofilm develops an oval shape or triangular shape depending on the rectangle's aspect ratio and orientation. The motile cells are primarily located in the valleys between the rectangles and the matrix producing cells are mostly located on the rectangles. Wrinkles form at the edges of the elevated surfaces, and upon merging form channels centered on the elevated surface. After a few days, the spore-forming cells appear at the periphery. Since biofilms in nature grow on irregular surfaces, our work may provide insight into the complex patterns observed.

  3. Neural Substrates of Dynamic Object Occlusion

    PubMed Central

    Shuwairi, Sarah M.; Curtis, Clayton E.; Johnson, Scott P.

    2011-01-01

    In everyday environments, objects frequently go out of sight as they move and our view of them becomes obstructed by nearer objects, yet we perceive these objects as continuous and enduring entities. Here, we used functional MRI with an attentive tracking paradigm to clarify the nature of perceptual and cognitive mechanisms subserving this ability to fill in the gaps in perception of dynamic object occlusion. Imaging data revealed distinct regions of cortex showing increased activity during periods of occlusion relative to full visibility. These regions may support active maintenance of a representation of the target’s spatiotemporal properties ensuring that the object is perceived as a persisting entity when occluded. Our findings may shed light on the neural substrates involved in object tracking that give rise to the phenomenon of object permanence. PMID:17651002

  4. Synthesis of silver nanoclusters on zeolite substrates

    NASA Astrophysics Data System (ADS)

    Posada, Y.

    2009-06-01

    Silver nanoclusters were synthesized by reducing silver nitrate with ethylene glycol at 160 °C in the presence of zeolite. A one-pot procedure has rendered uniform size distributions of quasispherical silver clusters of average sizes of 100-200 nm synthesized on the surfaces of cubiclike zeolite substrates of ˜1 μm side. Bulk material microanalysis measurements showed samples with silver mass percentages of 20%-38%. Surface atomic composition analysis found silver concentrations of 3.1%-5.7%, zeolite compounds and nontraces of nitrogen were measured. The binding energy for the Ag 3d5/2 core electrons was shifted to higher energies at 368.6 eV compared to that of metallic silver. Herein, is presented a cost-effective technique for producing a narrow size distribution of silver nanocomposites with great potential for optoelectronics, catalysis, and nanobiotechnological applications.

  5. The neural substrates associated with inattentional blindness.

    PubMed

    Thakral, Preston P

    2011-12-01

    Inattentional blindness is the failure to perceive salient stimuli presented at unattended locations. Whereas the behavioral manifestation of inattentional blindness has been investigated, the neural basis of this phenomenon has remained elusive. In the current study, event-related fMRI was used to identify the neural substrates associated with inattentional blindness. During central fixation, participants named colored digits presented at a peripheral location. On a subset of trials, an unexpected checkerboard circle (the critical stimulus) was presented at the same eccentricity along with the colored digits (a post-scan questionnaire assessed participants' awareness of the critical stimulus). Neural activity during inattentional blindness was observed in the prefrontal cortex. Together with previous findings, these results call into question the widespread view that activity in the prefrontal cortex reflects conscious processing. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Water based adhesive primers on aluminum substrates

    SciTech Connect

    Wightman, J.P.; Mori, S.

    1996-12-31

    The number of aluminum alloy bonding applications has been increasing recently in the automobile industry. Primer coating of aluminum substrates is one of the main processes used to promote bond performance. Solvent based organic primers have been used for a long time but environmental regulations now require the substitution of volatile organic compounds (VOC) by alternate materials such as water based adhesive primers. However, the bond strengths obtained with many water based primers are generally lower than for solvent based ones. Water based primers which have some reactive functional groups have been proposed recently but such primers require special treatment. This paper describes a study conducted to optimize bond strength using a water based adhesive as a primer in the adhesive bonding of anodized aluminum.

  7. Vector assembly of colloids on monolayer substrates

    PubMed Central

    Jiang, Lingxiang; Yang, Shenyu; Tsang, Boyce; Tu, Mei; Granick, Steve

    2017-01-01

    The key to spontaneous and directed assembly is to encode the desired assembly information to building blocks in a programmable and efficient way. In computer graphics, raster graphics encodes images on a single-pixel level, conferring fine details at the expense of large file sizes, whereas vector graphics encrypts shape information into vectors that allow small file sizes and operational transformations. Here, we adapt this raster/vector concept to a 2D colloidal system and realize ‘vector assembly' by manipulating particles on a colloidal monolayer substrate with optical tweezers. In contrast to raster assembly that assigns optical tweezers to each particle, vector assembly requires a minimal number of optical tweezers that allow operations like chain elongation and shortening. This vector approach enables simple uniform particles to form a vast collection of colloidal arenes and colloidenes, the spontaneous dissociation of which is achieved with precision and stage-by-stage complexity by simply removing the optical tweezers. PMID:28594002

  8. Vector assembly of colloids on monolayer substrates

    NASA Astrophysics Data System (ADS)

    Jiang, Lingxiang; Yang, Shenyu; Tsang, Boyce; Tu, Mei; Granick, Steve

    2017-06-01

    The key to spontaneous and directed assembly is to encode the desired assembly information to building blocks in a programmable and efficient way. In computer graphics, raster graphics encodes images on a single-pixel level, conferring fine details at the expense of large file sizes, whereas vector graphics encrypts shape information into vectors that allow small file sizes and operational transformations. Here, we adapt this raster/vector concept to a 2D colloidal system and realize `vector assembly' by manipulating particles on a colloidal monolayer substrate with optical tweezers. In contrast to raster assembly that assigns optical tweezers to each particle, vector assembly requires a minimal number of optical tweezers that allow operations like chain elongation and shortening. This vector approach enables simple uniform particles to form a vast collection of colloidal arenes and colloidenes, the spontaneous dissociation of which is achieved with precision and stage-by-stage complexity by simply removing the optical tweezers.

  9. Screen printed UHF antennas on flexible substrates

    NASA Astrophysics Data System (ADS)

    Janeczek, Kamil; Młożniak, Anna; Kozioł, Grażyna; Araźna, Aneta; Jakubowska, Małgorzata; Bajurko, Paweł

    2010-09-01

    Printed electronics belongs to the most important developing electronics technologies. It provides new possibilities to produce low cost and large area devices. In its range several applications can be distinguished like printed batteries, OLED, biosensors, photovoltaic cells or RFID tags. In the presented investigation, antennas working in UHF frequency range were elaborated. It can be applied in the future for flexible RFID tags. To produce these antennas polymer paste with silver flakes was used. It was deposited on two flexible substrates (foil and photo paper) with screen printing techniques. After printing process surface profile, electrical and microwave parameters of performed antennas were measured using digital multimeter and network analyzer, relatively. Furthermore, a thickness of printed layers was measured.

  10. Substrate Deformation Predicts Neuronal Growth Cone Advance

    PubMed Central

    Athamneh, Ahmad I.M.; Cartagena-Rivera, Alexander X.; Raman, Arvind; Suter, Daniel M.

    2015-01-01

    Although pulling forces have been observed in axonal growth for several decades, their underlying mechanisms, absolute magnitudes, and exact roles are not well understood. In this study, using two different experimental approaches, we quantified retrograde traction force in Aplysia californica neuronal growth cones as they develop over time in response to a new adhesion substrate. In the first approach, we developed a novel method, to our knowledge, for measuring traction forces using an atomic force microscope (AFM) with a cantilever that was modified with an Aplysia cell adhesion molecule (apCAM)-coated microbead. In the second approach, we used force-calibrated glass microneedles coated with apCAM ligands to guide growth cone advance. The traction force exerted by the growth cone was measured by monitoring the microneedle deflection using an optical microscope. Both approaches showed that Aplysia growth cones can develop traction forces in the 100–102 nN range during adhesion-mediated advance. Moreover, our results suggest that the level of traction force is directly correlated to the stiffness of the microneedle, which is consistent with a reinforcement mechanism previously observed in other cell types. Interestingly, the absolute level of traction force did not correlate with growth cone advance toward the adhesion site, but the amount of microneedle deflection did. In cases of adhesion-mediated growth cone advance, the mean needle deflection was 1.05 ± 0.07 μm. By contrast, the mean deflection was significantly lower (0.48 ± 0.06 μm) when the growth cones did not advance. Our data support a hypothesis that adhesion complexes, which can undergo micron-scale elastic deformation, regulate the coupling between the retrogradely flowing actin cytoskeleton and apCAM substrates, stimulating growth cone advance if sufficiently abundant. PMID:26445437

  11. Substrates and products of eosinophil peroxidase.

    PubMed Central

    van Dalen, C J; Kettle, A J

    2001-01-01

    Eosinophil peroxidase has been implicated in promoting oxidative tissue damage in a variety of inflammatory conditions, including asthma. It uses H(2)O(2) to oxidize chloride, bromide and thiocyanate to their respective hypohalous acids. The aim of this study was to establish which oxidants eosinophil peroxidase produces under physiological conditions. By measuring rates of H(2)O(2) utilization by the enzyme at neutral pH, we determined the catalytic rate constants for bromide and thiocyanate as 248 and 223 s(-1) and the Michaelis constants as 0.5 and 0.15 mM respectively. On the basis of these values thiocyanate is preferred 2.8-fold over bromide as a substrate for eosinophil peroxidase. Eosinophil peroxidase catalysed substantive oxidation of chloride only below pH 6.5. We found that when eosinophil peroxidase or myeloperoxidase oxidized thiocyanate, another product besides hypothiocyanite was formed; it also converted methionine into methionine sulphoxide. During the oxidation of thiocyanate, the peroxidases were present as their compound II forms. Compound II did not form when GSH was included to scavenge hypothiocyanite. We propose that the unidentified oxidant was derived from a radical species produced by the one-electron oxidation of hypothiocyanite. We conclude that at plasma concentrations of bromide (20-120 microM) and thiocyanate (20-100 microM), hypobromous acid and oxidation products of thiocyanate are produced by eosinophil peroxidase. Hypochlorous acid is likely to be produced only when substrates preferred over chloride are depleted. Thiocyanate should be considered to augment peroxidase-mediated toxicity because these enzymes can convert relatively benign hypothiocyanite into a stronger oxidant. PMID:11485572

  12. Staining potential of sealants in/on exterior wall substrates

    SciTech Connect

    Chin, I.R.; Gorrell, T.A.; Scheffler, M.J.

    1996-12-31

    The investigation of dozens of exterior walls on buildings by the authors have revealed that certain sealants used to seal joints in exterior walls have caused the following conditions: 1. Local staining and discoloration of masonry wall substrates due to penetration of sealant into substrates. 2. Local change in absorption of masonry wall substrates due to penetration of sealant into the substrates which results in local discoloration of wall substrates after rains. 3. Surface discoloration of sealant due to dirt accumulation on sealant. 4. Stains in the form of streaks of direct on masonry and on metal wall substrates due to transfer by rain water of some of the dirt on the sealant surface onto the adjacent surface of the substrate. Laboratory and field testing of the major commercially available sealants by the authors to date have revealed that silicone sealants have the propensity to stain certain exterior wall substrates while polyurethane sealants do not; that silicone sealants in service discolor more significantly and faster due to dirt accumulation than polyurethane sealants; that sealant that has penetrated into masonry substrates cannot be entirely removed from the substrate by cleaning; and that preconstruction testing of sealants and proper material selection can help to avoid staining of sealant.

  13. Assessment of Alternative Substrates for Culturing Lumbriculus variegatus

    USGS Publications Warehouse

    Lasier, P.J.

    2007-01-01

    The freshwater oligochaete, Lumbriculus variegatus, is tank-cultured to provide organisms for aquatic-habitat assessments, regeneration research and as a clean source of live food for aquarium fishes. Shredded paper is the typical substrate in cultures used to rear L. variegatus for these purposes. However, the effort needed to separate large numbers from decomposing paper can be prohibitive. Burlap and nylon mesh material were compared to paper as potential alternatives that could reduce this effort. Oligochaete production and the amount of time needed to separate animals from substrate were compared for eight weeks among experimental cultures containing burlap, nylon mesh and paper. Cultures with paper substrate increased in number and weight two to three times faster than those with burlap or nylon mesh substrates. The time needed to separate animals from substrate was initially two to three times longer with paper substrate than with burlap or nylon mesh substrates, but this difference increased to between 10 and 40 times longer after six weeks as the paper substrate decomposed. Feeding rates varied by treatment and were based on average wet weight at the time of water replacement. Elevated ammonia and nitrite concentrations resulting from excess food may have reduced production in nylon mesh treatments and was lethal in paper treatments during the final phases of the study. The type of substrate recommended may depend on the desired production rate of oligochaetes, space available for cultures and the amount of effort available for substrate renewal and separating the animals from the cultures.

  14. A proteomic approach for the discovery of protease substrates.

    PubMed

    Bredemeyer, Andrew J; Lewis, Renate M; Malone, James P; Davis, Alan E; Gross, Julia; Townsend, R Reid; Ley, Timothy J

    2004-08-10

    Standardized, comprehensive platforms for the discovery of protease substrates have been extremely difficult to create. Screens for protease specificity are now frequently based on the cleavage patterns of peptide substrates, which contain small recognition motifs that are required for the cleavage of the scissile bond within an active site. However, these studies do not identify in vivo substrates, nor can they lead to the definition of the macromolecular features that account for the biological specificity of proteases. To use properly folded proteins in a proteomic screen for protease substrates, we used 2D difference gel electrophoresis and tandem MS to identify substrates of an apoptosis-inducing protease, granzyme B. We confirmed the cleavage of procaspase-3, one of the key substrates of this enzyme, and identified several substrates that were previously unknown, as well as the cleavage site for one of these substrates. We were also able to observe the kinetics of substrate cleavage and cleavage product accumulation by using the 2D difference gel electrophoresis methodology. "Protease proteomics" may therefore represent an important tool for the discovery of the native substrates of a variety of proteases.

  15. Periodic cracking of films supported on compliant substrates

    PubMed Central

    Thouless, M. D.; Li, Z.; Douville, N. J.; Takayama, S.

    2011-01-01

    When a tensile strain is applied to a film supported on a compliant substrate, a pattern of parallel cracks can channel through both the film and substrate. A linear-elastic fracture-mechanics model for the phenomenon is presented to extend earlier analyses in which cracking was limited to the film. It is shown how failure of the substrate reduces the critical strain required to initiate fracture of the film. This effect is more pronounced for relatively tough films. However, there is a critical ratio of the film to substrate toughness above which stable cracks do not form in response to an applied load. Instead, catastrophic failure of the substrate occurs simultaneously with the propagation of a single channel crack. This critical toughness ratio increases with the modulus mismatch between the film and substrate, so that periodic crack patterns are more likely to be observed with relatively stiff films. With relatively low values of modulus mismatch, even a film that is more brittle than the substrate can cause catastrophic failure of the substrate. Below the critical toughness ratio, there is a regime in which stable crack arrays can be formed in the film and substrate. The depth of these arrays increases, while the spacing decreases, as the strain is increased. Eventually, the crack array can become deep enough to cause substrate failure. PMID:21927507

  16. Palaeoecology and evolution of marine hard substrate communities

    NASA Astrophysics Data System (ADS)

    Taylor, P. D.; Wilson, M. A.

    2003-07-01

    Marine organisms have occupied hard substrates since the Archaean. Shells, rocks, wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments, but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space. Hard substrate communities are formed by organisms with a variety of strategies for adhering to and/or excavating the substrates they inhabit. While mobile grazers, organically attached and even soft-bodied organisms may leave evidence of their former presence in ancient hard substrate communities, a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils. Furthermore, encrusters and borers are preserved in situ, retaining their spatial relationships to one another and to the substrate. Spatial competition, ecological succession, oriented growth, and differential utilisation of exposed vs. hidden substrate surfaces can all be observed or inferred. Hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years. Here we review the research on modern and ancient hard substrate communities, and point to some changes that have affected them over geological time scales. Such changes include a general increase in bioerosion of hard substrates, particularly carbonate surfaces, through the Phanerozoic. This is, at least in part, analogous to the infaunalisation trends seen in soft substrate communities. Encrusting forms show an increase in skeletalisation from the Palaeozoic into the Mesozoic and Cenozoic, which may be a response to increasing levels of predation. Hard substrate communities, considering borers and encrusters together, show a rough increase in tiering through the Phanerozoic which again parallels trends seen in soft substrate communities. This extensive review of the literature on living and fossil hard substrate organisms shows that

  17. Substrate recognition by Escherichia coli MutY using substrate analogs.

    PubMed Central

    Chepanoske, C L; Porello, S L; Fujiwara, T; Sugiyama, H; David, S S

    1999-01-01

    The Escherichia coli adenine glycosylase MutY is involved in the repair of 7,8-dihydro-8-oxo-2"-deoxyguanosine (OG):A and G:A mispairs in DNA. Our approach toward understanding recognition and processing of DNA damage by MutY has been to use substrate analogs that retain the recognition properties of the substrate mispair but are resistant to the glycosylase activity of MutY. This approach provides stable MutY-DNA complexes that are amenable to structural and biochemical characterization. In this work, the interaction of MutY with the 2"-deoxyadenosine analogs 2"-deoxy-2"-fluoroadenosine (FA), 2"-deoxyaristeromycin (R) and 2"-deoxyformycin A (F) was investigated. MutY binds to duplexes containing the FA, R or F analogs opposite G and OG within DNA with high affinity; however, no enzymatic processing of these duplexes is observed. The specific nature of the interaction of MutY with an OG:FA duplex was demonstrated by MPE-Fe(II) hydroxyl radical footprinting experiments which showed a nine base pair region of protection by MutY surrounding the mispair. DMS footprinting experiments with an OG:A duplex revealed that a specific G residue located on the OG-containing strand was protected from DMS in the presence of MutY. In contrast, a G residue flanking the substrate analogs R, F or FA was observed to be hypersensitive to DMS in the presence of MutY. These results suggest a major conformational change in the DNA helix upon binding of MutY that exposes the substrate analog-containing strand. This finding is consistent with a nucleotide flipping mechanism for damage recognition by MutY. This work demonstrates that duplex substrates for MutY containing FA, R or F instead of A are excellent substrate mimics that may be used to provide insight into the recognition by MutY of damaged and mismatched base pairs within DNA. PMID:10454618

  18. Involvement of Tyr24 and Trp108 in substrate binding and substrate specificity of glycolate oxidase.

    PubMed

    Stenberg, K; Clausen, T; Lindqvist, Y; Macheroux, P

    1995-03-01

    Tyr24 and Trp108 are located in the active site of spinach glycolate oxidase. To elucidate their function in substrate binding and catalysis, they were replaced by phenylalanine and serine, respectively. The [Y24F]glycolate oxidase mutant enzyme showed a tenfold higher Km value for glycolate. L-lactate and DL-2-hydroxybutyrate also showed higher Km values, however, the substrate specificity was unchanged as compared to the wild-type enzyme (Km increases in the order glycolate < DL-2-hydroxybutyrate < L-lactate < L-mandelate). The turnover number and the rate of reduction, found to be rate limiting in catalysis, were only slightly affected by the deletion of the hydroxyl group. These findings suggest that Tyr24 is mostly involved in substrate binding. The spectral features of the [Y24F]glycolate oxidase suggest that a fraction (50-80%) of the protein bears a flavin N(5) adduct instead of the oxidized cofactor. Crystals obtained from the isolated [Y24F]glycolate oxidase mutant protein allowed the determination of the three-dimensional structure. Although the structure was low resolution (0.3 nm), it is evident that the structure determined is that of the N(5) adduct species. In addition to the lacking hydroxyl group of Tyr24, we also observed movements of the amino acid side chains of Arg164 and Trp108, the latter replacing a water molecule in the substrate-binding pocket. Other features predominantly found in the class of flavoprotein oxidases, such as stabilization of the covalent N(5)-sulfite adduct and of the paraquinoid form of 8-mercapto-FMN, were found to be conserved. [W108S]Glycolate oxidase, in contrast, showed dramatic effects on both the Km of substrates as well as the turnover number. The Km for glycolate was increased some hundred fold and the turnover number was decreased 500-fold. In addition, it was found that the higher homologs of glycolate, L-lactate and DL-2-hydroxybutyrate had turnover numbers similar to those found with the wild-type enzyme

  19. Wetting on a deformable substrate with finite deformations and asymmetrical substrate surface energies

    NASA Astrophysics Data System (ADS)

    Limat, Laurent; de Pascalis, Riccardo; Dervaux, Julien; Ionescu, Ioan; Perthame, Benoit

    2016-11-01

    Wetting on soft compounds is still imperfectly understood, especially when the dry and wetted parts of the substrate have two different values of surface energies (contact angle different than 90 degrees). The problem is made very complex by geometrical non-linearities arising from finite slope of the substrate and finite deformations, that must be absolutely considered, to distinguish at second order between Young law and Neuman equilibrium of surface tensions. We have developed a numerical, finite element, code that allows one to minimize surface and bulk energies, with finite deformations and asymmetry of the surface energies. The results are compared to a linear theory based on Green function theory and Fredholm integrals, and with recent experiments using X-ray visualization. The non-linear numerics reproduce very well the observed profiles, while the linear approach gives helpful analytical approximates.

  20. Design and isolation of ribozyme-substrate pairs using RNase P-based ribozymes containing altered substrate binding sites.

    PubMed Central

    Mobley, E M; Pan, T

    1999-01-01

    Substrate recognition and cleavage by the bacterial RNase P RNA requires two domains, a specificity domain, or S-domain, and a catalytic domain, or C-domain. The S-domain binds the T stem-loop region in a pre-tRNA substrate to confer specificity for tRNA substrates. In this work, the entire S-domain of the Bacillus subtilis RNase P RNA is replaced with an artificial substrate binding module. New RNA substrates are isolated by in vitro selection using two libraries containing random regions of 60 nt. At the end of the selection, the cleavage rates of the substrate library are approximately 0.7 min(-1)in 10 mM MgCl(2)at 37 degrees C, approximately 4-fold better than the cleavage of a pre-tRNA substrate by the wild-type RNase P RNA under the same conditions. The contribution of the S-domain replacement to the catalytic efficiency is from 6- to 22 000-fold. Chemical and nuclease mapping of two ribozyme-product complexes shows that this contribution correlates with direct interactions between the S-domain replacement and the selected substrate. These results demonstrate the feasibility of design and isolation of RNase P-based, matching ribozyme-substrate pairs without prior knowledge of the sequence or structure of the interactive modules in the ribozyme or substrate. PMID:10518624

  1. Light management of tandem solar cells on nanostructured substrates

    NASA Astrophysics Data System (ADS)

    Chin, Alan H.; Keshavarz, Majid; Wang, Guo; Yu, Rosaline; Niu, Xinwei; Yang, Liyou

    2017-04-01

    We report the use of nanostructured substrates as a simple approach to improve the performance of tandem micromorph silicon solar cells. In the proposed approach, nanostructured substrates are produced using a low-cost, self-assembled growth process. The use of a nanostructured substrate coated with a thick transparent conductive oxide electrode layer enables the conformal deposition of the tandem solar cell absorber layers while allowing the solar cell to exhibit a modified surface morphology caused by the underlying nanostructured morphology. Using this nanostructured substrate approach, we demonstrated a 78% relative enhancement in the conversion efficiency of a tandem micromorph silicon cell on a nanostructured substrate compared to a standard tandem micromorph cell deposited onto a flat substrate.

  2. Vitreous carbon mask substrate for X-ray lithography

    DOEpatents

    Aigeldinger, Georg; Skala, Dawn M.; Griffiths, Stewart K.; Talin, Albert Alec; Losey, Matthew W.; Yang, Chu-Yeu Peter

    2009-10-27

    The present invention is directed to the use of vitreous carbon as a substrate material for providing masks for X-ray lithography. The new substrate also enables a small thickness of the mask absorber used to pattern the resist, and this enables improved mask accuracy. An alternative embodiment comprised the use of vitreous carbon as a LIGA substrate wherein the VC wafer blank is etched in a reactive ion plasma after which an X-ray resist is bonded. This surface treatment provides a surface enabling good adhesion of the X-ray photoresist and subsequent nucleation and adhesion of the electrodeposited metal for LIGA mold-making while the VC substrate practically eliminates secondary radiation effects that lead to delamination of the X-ray resist form the substrate, the loss of isolated resist features, and the formation of a resist layer adjacent to the substrate that is insoluble in the developer.

  3. Determining the critical size of EUV mask substrate defects

    SciTech Connect

    Goldberg, Kenneth A.; Gullikson, Eric M.; Han, Hakseung; Cho, Wonil; Jeon, Chan-Uk; Wurm, Stefan

    2008-05-26

    Determining the printability of substrate defects beneath the extreme ultraviolet (EUV) reflecting multilayer stack is an important issue in EUVL lithography. Several simulation studies have been performed in the past to determine the tolerable defect size on EUV mask blank substrates but the industry still has no exact specification based on real printability tests. Therefore, it is imperative to experimentally determine the printability of small defects on a mask blanks that are caused by substrate defects using direct printing of programmed substrate defect in an EUV exposure tools. SEMATECH fabricated bump type program defect masks using standard electron beam lithography and performed printing tests with the masks using an EUV exposure tool. Defect images were also captured using SEMATECH's Berkeley Actinic Imaging Tool in order to compare aerial defect images with secondary electron microscope images from exposed wafers. In this paper, a comprehensive understanding of substrate defect printability will be presented and printability specifications of EUV mask substrate defects will be discussed.

  4. Determining the Critcial Size of EUV Mask Substrate Defects

    SciTech Connect

    Mccall, Monnikue M; Han, Hakseung; Cho, Wonil; Goldberg, Kenneth; Gullikson, Eric; Jeon, Chan-Uk; Wurm, Stefan

    2008-02-28

    Determining the printability of substrate defects beneath the extreme ultraviolet (EUV) reflecting multilayer stack is an important issue in EUVL lithography. Several simulation studies have been performed in the past to determine the tolerable defect size on EUV mask blank substrates but the industry still has no exact specification based on real printability tests. Therefore, it is imperative to experimentally determine the printability of small defects on a mask blanks that are caused by substrate defects using direct printing of programmed substrate defect in an EUV exposure tool. SEMATECH fabricated bump type program defect masks using standard electron beam lithography and performed printing tests with the masks using an EUV exposure tool. Defect images were also captured using SEMATECH's Berkeley Actinic Imaging Tool in order to compare aerial defect images with secondary electron microscope images from exposed wafers. In this paper, a comprehensive understanding of substrate defect printability will be presented and printability specifications of EUV mask substrate defects will be discussed.

  5. Substrate discrimination in burying beetles, Nicrophorus orbicollis (Coleoptera: Silphidae)

    USGS Publications Warehouse

    Muths, Erin Louise

    1991-01-01

    Burying beetles Nicrophorus orbicollis (Coleoptera: Silphidae) secure and bury small vertebrate carcasses as a food resource for their offspring and themselves. Burial may take place at the point of carcass discovery or at some distance from that site. Burying beetles were tested to determine if they discriminate between different substrates when burying a carcass. Three substrates were presented simultaneously. Substrate one contained soil from typical beetle habitat; substrates two and three contained 2:1 and 5:1 ratios, respectively, of soil and a senescent prairie grass (Panicum virgatum), which added a bulk structural component to the soil. Beetles generally moved and buried the carcass within 24 hours. Results for both paired and individual trials suggest that burying beetles discriminate between substrates, preferring substrates with added bulk over those without.

  6. Microwave GaAs Integrated Circuits On Quartz Substrates

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H.; Mehdi, Imran; Wilson, Barbara

    1994-01-01

    Integrated circuits for use in detecting electromagnetic radiation at millimeter and submillimeter wavelengths constructed by bonding GaAs-based integrated circuits onto quartz-substrate-based stripline circuits. Approach offers combined advantages of high-speed semiconductor active devices made only on epitaxially deposited GaAs substrates with low-dielectric-loss, mechanically rugged quartz substrates. Other potential applications include integration of antenna elements with active devices, using carrier substrates other than quartz to meet particular requirements using lifted-off GaAs layer in membrane configuration with quartz substrate supporting edges only, and using lift-off technique to fabricate ultrathin discrete devices diced separately and inserted into predefined larger circuits. In different device concept, quartz substrate utilized as transparent support for GaAs devices excited from back side by optical radiation.

  7. Substrate structures for InP-based devices

    DOEpatents

    Wanlass, Mark W.; Sheldon, Peter

    1990-01-01

    A substrate structure for an InP-based semiconductor device having an InP based film is disclosed. The substrate structure includes a substrate region having a lightweight bulk substrate and an upper GaAs layer. An interconnecting region is disposed between the substrate region and the InP-based device. The interconnecting region includes a compositionally graded intermediate layer substantially lattice-matched at one end to the GaAs layer and substantially lattice-matched at the opposite end to the InP-based film. The interconnecting region further includes a dislocation mechanism disposed between the GaAs layer and the InP-based film in cooperation with the graded intermediate layer, the buffer mechanism blocking and inhibiting propagation of threading dislocations between the substrate region, and the InP-based device.

  8. Heterogeneous crystallization of hard spheres on patterned substrates

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Sheng; Sun, Zhao-Yan; An, Li-Jia

    2010-04-01

    We report a numerical investigation of the crystallization of monodisperse hard spheres on different patterned substrates. We find that the duration of a metastable fluid state, which may last for relatively long time in the homogeneous crystallization, can be deeply reduced or almost eliminated when a substrate is used as the seed of crystallization. In the presence of the square patterned substrate, which has the basic character of the body-centered cubic (bcc) crystal structure, a transient bcc crystal phase was observed, suggesting that the bcc structure could be possible to be stabilized by the square patterned substrates. The process of crystallization becomes complicated when the patterned substrate is incommensurate with the bulk crystal. Furthermore, a purely face-centered cubic or hexagonal close packed crystal phase with stacking faults can be generated by using a certain patterned substrate without other factors such as gravity.

  9. Substrate size mediates thermal stress in the rocky intertidal.

    PubMed

    Gedan, Keryn B; Bernhardt, Joanna; Bertness, Mark D; Leslie, Heather M

    2011-03-01

    Variation in physical factors, such as slope, orientation, and wind exposure, shapes thermal conditions. Variation in substrate size is common in many habitats, but its thermal consequences for organisms are not well characterized. Larger substrates should remain more thermally stable and act as thermal refuges for associated organisms during short, thermally stressful periods such as midday temperature peaks or tidal exposure. In observations and a transplant and thermal integration experiment, we found that larger rock substrates stayed cooler and facilitated greater survival of the barnacle Semibalanus balanoides in the high intertidal relative to small substrates during the hot summer months in southern New England, USA. However, in thermally benign northern New England, rock substrate size had no effect on barnacle distributions, indicating that the thermal effects of substrate size are mediated by regional climate.

  10. Monitoring of changes in substrate characteristics during mushroom compost production.

    PubMed

    Lyons, Gary A; Sharma, H S Shekhar; Kilpatrick, Mairead; Cheung, Linda; Moore, Solveig

    2006-06-28

    Substrates from three mushroom compost facilities in Northern Ireland, employing similar production technologies, were examined to assess the quality of the compost produced. Biochemical investigation highlighted changes in substrates through each step of the production cycle. Thermogravimetric analysis (TGA) provided useful information on fiber fraction content and extent of substrate breakdown. A comparison of productivity, chemical, and thermal data permitted assessment of the degree of bioconversion that had occurred in the decomposition from raw materials to finished substrate for each composter. One of the composters consistently produced substrate of inferior quality compared to the other two, indicating production inefficiencies during composting. Results demonstrated that allied to chemical analyses, TGA is a useful tool, providing valuable information on substrate quality and, in particular, for studying the bioconversion of lignocellulosic materials in mushroom compost.

  11. Experimental analysis of green roof substrate detention characteristics.

    PubMed

    Yio, Marcus H N; Stovin, Virginia; Werdin, Jörg; Vesuviano, Gianni

    2013-01-01

    Green roofs may make an important contribution to urban stormwater management. Rainfall-runoff models are required to evaluate green roof responses to specific rainfall inputs. The roof's hydrological response is a function of its configuration, with the substrate - or growing media - providing both retention and detention of rainfall. The objective of the research described here is to quantify the detention effects due to green roof substrates, and to propose a suitable hydrological modelling approach. Laboratory results from experimental detention tests on green roof substrates are presented. It is shown that detention increases with substrate depth and as a result of increasing substrate organic content. Model structures based on reservoir routing are evaluated, and it is found that a one-parameter reservoir routing model coupled with a parameter that describes the delay to start of runoff best fits the observed data. Preliminary findings support the hypothesis that the reservoir routing parameter values can be defined from the substrate's physical characteristics.

  12. Generalized rate equation for single-substrate enzyme catalyzed reactions.

    PubMed

    Kargi, Fikret

    2009-04-24

    The most widely used rate expression for single-substrate enzyme catalyzed reactions, namely the Michaelis-Menten kinetics is based upon the assumption that enzyme concentration is in excess of the substrate in the medium and the rate is mainly limited by the substrate concentration according to saturation kinetics. However, this is only a special case and the actual rate expression varies depending on the initial enzyme/substrate ratio (E(0)/S(0)). When the substrate concentration exceeds the enzyme concentration the limitation is due to low enzyme concentration and the rate increases with the enzyme concentration according to saturation kinetics. The maximum rate is obtained when the initial concentrations of the enzyme and the substrate are equal. A generalized rate equation was developed in this study and special cases were discussed for enzyme catalyzed reactions.

  13. On the mechanism of substrate/non-substrate recognition by P-glycoprotein.

    PubMed

    Mukhametov, Azat; Raevsky, Oleg A

    2017-01-01

    P-Glycoprotein (P-gp, multi-drug resistance protein, MDR1) plays a gatekeeper role, interfering delivery of multiple pharmaceuticals to the target tissues and cells. We performed Molecular Dynamics (MD) simulations to generate fifty side-chain variants for P-gp (PDB ID: 4Q9H-L) followed by docking of 31 drugs (0.6≤ER≤22.7) to the whole surface except the ATPase domains and the extracellular part. A selection of the most negative energy complex for each ligand followed. All compounds docked to the two areas - the main binding cavity at the top of P-gp (12.5% of compounds with ER<1; 44.4% of 1≤ER≤2; and 100% of ER>2), and the binding sites in the middle of P-gp (87.5% of ER<1; 55.6% of 1≤ER≤2; and 0% of ER>2). Our results show that anti-substrates (ER<1), intermediate compounds (1≤ER≤2) and strong substrates (ER>2) might behave differently in relation to the P-gp. According to our calculations, the anti-substrates almost do not bind the main binding cavity (MBC) of P-gp and rather approach the other binding sites on the protein; the substrates preferably bind the MBC; the intermediate compounds with 1≤ER≤2 bind both MBC and other binding sites almost equally. The modelling results are in line with the known hypothesis that binding the MBC is prerequisite for the pumping the compound off the P-gp.

  14. Structural requirements for human inducible nitric oxide synthase substrates and substrate analogue inhibitors.

    PubMed

    Grant, S K; Green, B G; Stiffey-Wilusz, J; Durette, P L; Shah, S K; Kozarich, J W

    1998-03-24

    Inducible nitric oxide synthase (iNOS; EC 1.14.13.39) catalyzes the NADPH-dependent oxidation of one of the free guanidino nitrogens of L-Arg to form nitric oxide and L-citrulline. Analogues of L-Arg and the inhibitor, L-N6-(1-iminoethyl)lysine, were used to define structural elements required for the binding and catalysis of compounds. L-Arg analogues with sequentially shorter methylene spacing between the guanidino group and the amino acid portion of the molecule were not iNOS substrates but were reversible inhibitors. L-Arg analogues such as agmatine with a hydroxyl substitution at the 2-amino position were substrates. Desaminoarginine was not a substrate but a reversible inhibitor. Desaminoarginine, agmatine, and argininic acid bound to the enzyme to give type I difference spectra similar to that of L-Arg. The amidino compounds L-N6-(1-iminoethyl)lysine, L-N5-(1-iminoethyl)ornithine, and N5-(1-iminoethyl)cadaverdine, but not N6-(1-iminoethyl)-6-aminocaproic acid, were NADPH-dependent, irreversible inactivators of iNOS. For both the L-Arg and L-N6-(1-iminoethyl)lysine analogues, the 2-amino group appeared to play an important role in catalytic events leading to either substrate turnover or mechanism-based inactivation. Inactivation of iNOS by L-N6-(1-iminoethyl)lysine was NADPH- and dioxygen-dependent, but low incorporation of radiolabel with DL--4, 5-3H]-N6-(1-iminoethyl)lysine indicates that the mechanism of enzyme inactivation is not covalent modification of the protein.

  15. Microstrip Antenna Arrays on Multilayer LCP Substrates

    NASA Technical Reports Server (NTRS)

    Thompson, Dane; Bairavasubramanian, Ramanan; Wang, Guoan; Kingsley, Nickolas D.; Papapolymerou, Ioannis; Tenteris, Emmanouil M.; DeJean, Gerald; Li, RonglLin

    2007-01-01

    A research and development effort now underway is directed toward satisfying requirements for a new type of relatively inexpensive, lightweight, microwave antenna array and associated circuitry packaged in a thin, flexible sheet that can readily be mounted on a curved or flat rigid or semi-rigid surface. A representative package of this type consists of microwave antenna circuitry embedded in and/or on a multilayer liquid- crystal polymer (LCP) substrate. The circuitry typically includes an array of printed metal microstrip patch antenna elements and their feedlines on one or more of the LCP layer(s). The circuitry can also include such components as electrostatically actuated microelectromechanical systems (MEMS) switches for connecting and disconnecting antenna elements and feedlines. In addition, the circuitry can include switchable phase shifters described below. LCPs were chosen over other flexible substrate materials because they have properties that are especially attractive for high-performance microwave applications. These properties include low permittivity, low loss tangent, low water-absorption coefficient, and low cost. By means of heat treatments, their coefficients of thermal expansion can be tailored to make them more amenable to integration into packages that include other materials. The nature of the flexibility of LCPs is such that large LCP sheets containing antenna arrays can be rolled up, then later easily unrolled and deployed. Figure 1 depicts a prototype three- LCP-layer package containing two four-element, dual-polarization microstrip-patch arrays: one for a frequency of 14 GHz, the other for a frequency of 35 GHz. The 35-GHz patches are embedded on top surface of the middle [15-mil (approx.0.13-mm)-thick] LCP layer; the 14- GHz patches are placed on the top surface of the upper [9-mil (approx. 0.23-mm)-thick] LCP layer. The particular choice of LCP layer thicknesses was made on the basis of extensive analysis of the effects of the

  16. Self-Organized Si Dots On Ge Substrates

    SciTech Connect

    Pachinger, D.; Lichtenberger, H.; Schaeffler, F.

    2007-04-10

    The epitaxial growth conditions for silicon on germanium substrates were investigated as a function of growth temperature and monolayer coverage. Island formation was observed for the hole studied temperature range, although strong alloying with the substrate occurred for the highest temperatures. Carbon pre-deposition offers suitable nucleation centers for the Si island and reduction of alloying. pre-structured Ge substrates were prepared to enhance islanding and to achieve ordering.

  17. Polymer Substrates For Lightweight, Thin-Film Solar Cells

    NASA Technical Reports Server (NTRS)

    Lewis, Carol R.

    1993-01-01

    Substrates survive high deposition temperatures. High-temperature-resistant polymers candidate materials for use as substrates of lightweight, flexible, radiation-resistant solar photovoltaic cells. According to proposal, thin films of copper indium diselenide or cadmium telluride deposited on substrates to serve as active semiconductor layers of cells, parts of photovoltaic power arrays having exceptionally high power-to-weight ratios. Flexibility of cells exploited to make arrays rolled up for storage.

  18. [Use of 1- and 2-thionaphthylacetates as cholinesterase substrates].

    PubMed

    Zhukovskiĭ, Iu G; Kuznetsova, L P; Sochilina, E E; Veksler, K V

    2003-01-01

    1- and 2-thionaphthylacetates were tested as cholinesterase substrates. It was shown that the butyrilcholinesterase from horse serum can hydrolize these compounds. The hydrolysis velocity of 1-thionaphthylacetate was comparable with hydrolysis velocity of acetylthiocholine (the well known cholinesterase substrate), but 2-thionaphthylacetate was hydrolysed more slowly. The values of the kinetic parameters V and K(m) for butyrylcholinesterase hydrolysis of 1- and 2-thionaphthylacetates were determined. It was offered to use 1-thionaphthylacetates as the substrate for cholinesterases.

  19. Method for electrostatic deposition of graphene on a substrate

    NASA Technical Reports Server (NTRS)

    Sumanasekera, Gamini (Inventor); Sidorov, Anton N. (Inventor); Ouseph, P. John (Inventor); Yazdanpanah, Mehdi M. (Inventor); Cohn, Robert W. (Inventor); Jalilian, Romaneh (Inventor)

    2010-01-01

    A method for electrostatic deposition of graphene on a substrate comprises the steps of securing a graphite sample to a first electrode; electrically connecting the first electrode to a positive terminal of a power source; electrically connecting a second electrode to a ground terminal of the power source; placing the substrate over the second electrode; and using the power source to apply a voltage, such that graphene is removed from the graphite sample and deposited on the substrate.

  20. Method for producing high quality thin layer films on substrates

    DOEpatents

    Strongin, Myron; Ruckman, Mark; Strongin, Daniel

    1994-01-01

    A method for producing high quality, thin layer films of inorganic compounds upon the surface of a substrate is disclosed. The method involves condensing a mixture of preselected molecular precursors on the surface of a substrate and subsequently inducing the formation of reactive species using high energy photon or charged particle irradiation. The reactive species react with one another to produce a film of the desired compound upon the surface of the substrate.

  1. Some basic questions on mechanosensing in cell-substrate interaction

    NASA Astrophysics Data System (ADS)

    He, Shijie; Su, Yewang; Ji, Baohua; Gao, Huajian

    2014-10-01

    Cells constantly probe their surrounding microenvironment by pushing and pulling on the extracellular matrix (ECM). While it is widely accepted that cell induced traction forces at the cell-matrix interface play essential roles in cell signaling, cell migration and tissue morphogenesis, a number of puzzling questions remain with respect to mechanosensing in cell-substrate interactions. Here we show that these open questions can be addressed by modeling the cell-substrate system as a pre-strained elastic disk attached to an elastic substrate via molecular bonds at the interface. Based on this model, we establish analytical and numerical solutions for the displacement and stress fields in both cell and substrate, as well as traction forces at the cell-substrate interface. We show that the cell traction generally increases with distance away from the cell center and that the traction-distance relationship changes from linear on soft substrates to exponential on stiff substrates. These results indicate that cell adhesion and migration behaviors can be regulated by cell shape and substrate stiffness. Our analysis also reveals that the cell traction increases linearly with substrate stiffness on soft substrates but then levels off to a constant value on stiff substrates. This biphasic behavior in the dependence of cell traction on substrate stiffness immediately sheds light on an existing debate on whether cells sense mechanical force or deformation when interacting with their surroundings. Finally, it is shown that the cell induced deformation field decays exponentially with distance away from the cell. The characteristic length of this decay is comparable to the cell size and provides a quantitative measure of how far cells feel into the ECM.

  2. Mogul-Patterned Elastomeric Substrate for Stretchable Electronics.

    PubMed

    Lee, Han-Byeol; Bae, Chan-Wool; Duy, Le Thai; Sohn, Il-Yung; Kim, Do-Il; Song, You-Joon; Kim, Youn-Jea; Lee, Nae-Eung

    2016-04-01

    A mogul-patterned stretchable substrate with multidirectional stretchability and minimal fracture of layers under high stretching is fabricated by double photolithography and soft lithography. Au layers and a reduced graphene oxide chemiresistor on a mogul-patterned poly(dimethylsiloxane) substrate are stable and durable under various stretching conditions. The newly designed mogul-patterned stretchable substrate shows great promise for stretchable electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Method for producing high quality thin layer films on substrates

    DOEpatents

    Strongin, M.; Ruckman, M.; Strongin, D.

    1994-04-26

    A method for producing high quality, thin layer films of inorganic compounds upon the surface of a substrate is disclosed. The method involves condensing a mixture of preselected molecular precursors on the surface of a substrate and subsequently inducing the formation of reactive species using high energy photon or charged particle irradiation. The reactive species react with one another to produce a film of the desired compound upon the surface of the substrate. 4 figures.

  4. Biodegradable nanofibrous polymeric substrates for generating elastic and flexible electronics.

    PubMed

    Najafabadi, Alireza Hassani; Tamayol, Ali; Annabi, Nasim; Ochoa, Manuel; Mostafalu, Pooria; Akbari, Mohsen; Nikkhah, Mehdi; Rahimi, Rahim; Dokmeci, Mehmet R; Sonkusale, Sameer; Ziaie, Babak; Khademhosseini, Ali

    2014-09-03

    Biodegradable nanofibrous polymeric substrates are used to fabricate suturable, elastic, and flexible electronics and sensors. The fibrous microstructure of the substrate makes it permeable to gas and liquid and facilitates the patterning process. As a proof-of-principle, temperature and strain sensors are fabricated on this elastic substrate and tested in vitro. The proposed system can be implemented in the field of bioresorbable electronics and the emerging area of smart wound dressings.

  5. Study of composites as substrate materials in large space telescopes

    NASA Technical Reports Server (NTRS)

    Sharma, A. V.

    1979-01-01

    Nonmetallic composites such as the graphite/epoxy system were investigated as possible substrates for the primary mirror of the large space telescope. The possible use of fiber reinforced metal matrix composites was reviewed in the literature. Problems arising out of the use of composites as substrate materials such as grinding, polishing, adherence of reflective coatings, rigidity of substrate, hygrospcopici tendency of the composites, thermal and temporal stability and other related problems were examined.

  6. Cryogenically cooled multiple-substrate holder for high vacuum

    NASA Astrophysics Data System (ADS)

    Chaiken, A.; Honea, E. C.; Rupprecht, W. S.; Torres, S.; Michel, R. P.

    1994-12-01

    A novel design is presented for a cryogenically cooled multisubstrate sample holder for thin film deposition in high vacuum. The cryogen flows through tubing soldered onto a fixed copper plate, while the substrates are mounted on a separate tray that is supported by a linear/rotary-motion feedthrough. By lowering the substrate tray into firm contact with the copper plate, substrate temperatures as low as 120 K can be achieved.

  7. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1993-11-23

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  8. Corn Hybrid Polymer Media for Coatings Removal from Delicate Substrates

    DTIC Science & Technology

    2008-05-01

    Corn Hybrid Polymer Media for Coatings Removal from Delicate Substrates Brian Yallaly, NDCEE The NDCEE is operated by: NDCEE National Defense Center...3. DATES COVERED 00-00-2008 to 00-00-2008 4. TITLE AND SUBTITLE Corn Hybrid Polymer Media for Coatings Removal from Delicate Substrates 5a... Corn -based blasting media – Provides acceptable stripping rates – Does not damage delicate substrates – Generates biodegradable and recyclable

  9. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1993-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  10. Method for masking selected regions of a substrate

    DOEpatents

    Fusaro, Jr., Robert Anthony; Bethel, Timothy Francis

    2010-05-04

    Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

  11. Enhanced 3D fluorescence live cell imaging on nanoplasmonic substrate

    NASA Astrophysics Data System (ADS)

    Ranjan Gartia, Manas; Hsiao, Austin; Sivaguru, Mayandi; Chen, Yi; Logan Liu, G.

    2011-09-01

    We have created a randomly distributed nanocone substrate on silicon coated with silver for surface-plasmon-enhanced fluorescence detection and 3D cell imaging. Optical characterization of the nanocone substrate showed it can support several plasmonic modes (in the 300-800 nm wavelength range) that can be coupled to a fluorophore on the surface of the substrate, which gives rise to the enhanced fluorescence. Spectral analysis suggests that a nanocone substrate can create more excitons and shorter lifetime in the model fluorophore Rhodamine 6G (R6G) due to plasmon resonance energy transfer from the nanocone substrate to the nearby fluorophore. We observed three-dimensional fluorescence enhancement on our substrate shown from the confocal fluorescence imaging of chinese hamster ovary (CHO) cells grown on the substrate. The fluorescence intensity from the fluorophores bound on the cell membrane was amplified more than 100-fold as compared to that on a glass substrate. We believe that strong scattering within the nanostructured area coupled with random scattering inside the cell resulted in the observed three-dimensional enhancement in fluorescence with higher photostability on the substrate surface.

  12. A meta-substrate to enhance the bandwidth of metamaterials.

    PubMed

    Chen, Hongsheng; Wang, Zuojia; Zhang, Runren; Wang, Huaping; Lin, Shisheng; Yu, Faxin; Moser, Herbert O

    2014-06-12

    We propose the concept of a meta-substrate to broaden the bandwidth of left-handed metamaterials. The meta-substrate, which behaves like an inhomogeneous magnetic substrate, is composed of another kind of magnetic metamaterials like metallic closed rings. When conventional metamaterial rings are printed on this kind of meta-substrate in a proper way, the interaction of the metamaterials units can be greatly enhanced, yielding an increased bandwidth of negative permeability. An equivalent circuit analytical model is used to quantitatively characterize this phenomenon. Both numerical and experimental demonstrations are carried out, showing good agreement with theoretical predictions.

  13. A meta-substrate to enhance the bandwidth of metamaterials

    PubMed Central

    Chen, Hongsheng; Wang, Zuojia; Zhang, Runren; Wang, Huaping; Lin, Shisheng; Yu, Faxin; Moser, Herbert O.

    2014-01-01

    We propose the concept of a meta-substrate to broaden the bandwidth of left-handed metamaterials. The meta-substrate, which behaves like an inhomogeneous magnetic substrate, is composed of another kind of magnetic metamaterials like metallic closed rings. When conventional metamaterial rings are printed on this kind of meta-substrate in a proper way, the interaction of the metamaterials units can be greatly enhanced, yielding an increased bandwidth of negative permeability. An equivalent circuit analytical model is used to quantitatively characterize this phenomenon. Both numerical and experimental demonstrations are carried out, showing good agreement with theoretical predictions. PMID:24919678

  14. Does the Dirac Cone Exist in Silicene on Metal Substrates?

    PubMed Central

    Quhe, Ruge; Yuan, Yakun; Zheng, Jiaxin; Wang, Yangyang; Ni, Zeyuan; Shi, Junjie; Yu, Dapeng; Yang, Jinbo; Lu, Jing

    2014-01-01

    Absence of the Dirac cone due to a strong band hybridization is revealed to be a common feature for epitaxial silicene on metal substrates according to our first-principles calculations for silicene on Ir, Cu, Mg, Au, Pt, Al, and Ag substrates. The destroyed Dirac cone of silicene, however, can be effectively restored with linear or parabolic dispersion by intercalating alkali metal atoms between silicene and the metal substrates, offering an opportunity to study the intriguing properties of silicene without further transfer of silicene from the metal substrates. PMID:24969493

  15. Influence of substrate rocks on Fe-Mn crust composition

    USGS Publications Warehouse

    Hein, J.R.; Morgan, C.L.

    1999-01-01

    Principal Component and other statistical analyses of chemical and mineralogical data of Fe-Mn oxyhydroxide crusts and their underlying rock substrates in the central Pacific indicate that substrate rocks do not influence crust composition. Two ridges near Johnston Atoll were dredged repetitively and up to seven substrate rock types were recovered from small areas of similar water depths. Crusts were analyzed mineralogically and chemically for 24 elements, and substrates were analyzed mineralogically and chemically for the 10 major oxides. Compositions of crusts on phosphatized substrates are distinctly different from crusts on substrates containing no phosphorite. However, that relationship only indicates that the episodes of phosphatization that mineralized the substrate rocks also mineralized the crusts that grew on them. A two-fold increase in copper contents in crusts that grew on phosphatized clastic substrate rocks, relative to crusts on other substrate rock types, is also associated with phosphatization and must have resulted from chemical reorganization during diagenesis. Phosphatized crusts show increases in Sr, Zn, Ca, Ba, Cu, Ce, V, and Mo contents and decreases in Fe, Si, and As contents relative to non-phosphatized crusts. Our statistical results support previous studies which show that crust compositions reflect predominantly direct precipitation from seawater (hydrogenetic), and to lesser extents reflect detrital input and diagenetic replacement of parts of the older crust generation by carbonate fluorapatite.

  16. MILSTAR's flexible substrate solar array: Lessons learned, addendum

    NASA Technical Reports Server (NTRS)

    Gibb, John

    1990-01-01

    MILSTAR's Flexible Substrate Solar Array (FSSA) is an evolutionary development of the lightweight, flexible substrate design pioneered at Lockheed during the seventies. Many of the features of the design are related to the Solar Array Flight Experiment (SAFE), flown on STS-41D in 1984. FSSA development has created a substantial technology base for future flexible substrate solar arrays such as the array for the Space Station Freedom. Lessons learned during the development of the FSSA can and should be applied to the Freedom array and other future flexible substrate designs.

  17. Substrate effect on aperture resonances in a thin metal film.

    PubMed

    Kang, J H; Choe, Jong-Ho; Kim, D S; Park, Q-Han

    2009-08-31

    We present a simple theoretical model to study the effect of a substrate on the resonance of an aperture in a thin metal film. The transmitted energy through an aperture is shown to be governed by the coupling of aperture waveguide mode to the incoming and the outgoing electromagnetic waves into the substrate region. Aperture resonance in the energy transmission thus depends critically on the refractive index of a substrate. We explain the substrate effect on aperture resonance in terms of destructive interference among evanescent modes or impedance mismatch. Our model shows an excellent agreement with a rigorous FDTD calculation and is consistent with previous experimental observations.

  18. Surface-enhanced Raman spectroscopy: substrate-related issues.

    PubMed

    Lin, Xiu-Mei; Cui, Yan; Xu, Yan-Hui; Ren, Bin; Tian, Zhong-Qun

    2009-08-01

    After over 30 years of development, surface-enhanced Raman spectroscopy (SERS) is now facing a very important stage in its history. The explosive development of nanoscience and nanotechnology has assisted the rapid development of SERS, especially during the last 5 years. Further development of surface-enhanced Raman spectroscopy is mainly limited by the reproducible preparation of clean and highly surface enhanced Raman scattering (SERS) active substrates. This review deals with some substrate-related issues. Various methods will be introduced for preparing SERS substrates of Ag and Au for analytical purposes, from SERS substrates prepared by electrochemical or vacuum methods, to well-dispersed Au or Ag nanoparticle sols, to nanoparticle thin film substrates, and finally to ordered nanostructured substrates. Emphasis is placed on the analysis of the advantages and weaknesses of different methods in preparing SERS substrates. Closely related to the application of SERS in the analysis of trace sample and unknown systems, the existing cleaning methods for SERS substrates are analyzed and a combined chemical adsorption and electrochemical oxidation method is proposed to eliminate the interference of contaminants. A defocusing method is proposed to deal with the laser-induced sample decomposition problem frequently met in SERS measurement to obtain strong signals. The existing methods to estimate the surface enhancement factor, a criterion to characterize the SERS activity of a substrate, are analyzed and some guidelines are proposed to obtain the correct enhancement factor.

  19. Substrate-directed formation of small biocatalysts under prebiotic conditions.

    PubMed

    Kochavi, E; Bar-Nun, A; Fleminger, G

    1997-10-01

    One of the most debated issues concerning the origin of life, is how enzymes which are essential for existence of any living organism, evolved. It is clear that, regardless of the exact mechanism, the process should have been specific and reproducible, involving interactions between different molecules. We propose that substrate templating played a crucial role in maintaining reproducible and specific formation of prebiotic catalysts. This work demonstrates experimentally, for the first time, substrate-directed formation of an oligopeptide that possesses a specific catalytic activity toward the substrate on which it was formed. In our experiments we used the substrate O-nitrophenol-beta-D-galactopyranoside (ONPG) as a molecular template for the synthesis of a specific catalyst that is capable of cleaving the same substrate. This was achieved by incubation of the substrate with free amino acids and a condensing agent (dicyandiamide) at elevated temperatures. A linear increase with time of the reaction rate (d[product]/d2t), pointed to an acceleration regime, where the substrate generates the formation of the catalyst. The purified catalyst, produced by a substrate-directed mechanism, was analyzed, and identified as Cys2-Fe+2. The mechanism of substrate-directed formation of prebiotic catalysts provides a solution to both the specificity and the reproducibility requirements from any prebiotic system which should evolve into the biological world.

  20. Method For Making Selected Regions Of A Substrate

    DOEpatents

    Fusaro, Jr., Robert Anthony; Bethel, Timothy Francis

    2003-07-15

    Described herein is a method for providing a clean edge at the interface of a portion of a substrate coated with a coating system and an adjacent portion of the substrate which is uncoated. The method includes the step of forming a zone of non-adherence on the substrate portion which is to be uncoated, prior to application of the coating system. The zone of non-adherence is adjacent the interface, so that the coating system will not adhere to the zone of non-adherence, but will adhere to the portion of the substrate which is to be coated with the coating system.

  1. The status and promise of compliant substrate technology

    NASA Astrophysics Data System (ADS)

    Brown, April S.; Doolittle, W. Alan

    2000-10-01

    Compliant substrates offer significant promise as a new approach for strain management in semiconductors. The primary application is to produce device-quality highly mismatched materials on dissimilar substrates. Various implementations and processes for achieving substrate compliancy have been proposed and demonstrated. These include the use of twist-, glass-, and metal-bonds, and the use of engineered templates realized with laterally oxidized Al-containing alloys. A recent focus in our work has been on the growth of GaN on a novel and easily removable substrate — lithium gallate — for regrowth on a bonded GaN template.

  2. Substrate-dependent temperature sensitivity of soil organic matter decomposition

    NASA Astrophysics Data System (ADS)

    Myachina, Olga; Blagodatskaya, Evgenia

    2015-04-01

    Activity of extracellular enzymes responsible for decomposition of organics is substrate dependent. Quantity of the substrate is the main limiting factor for enzymatic or microbial heterotrophic activity in soils. Different mechanisms of enzymes response to temperature suggested for low and high substrate availability were never proved for real soil conditions. We compared the temperature responses of enzymes-catalyzed reactions in soils. Basing on Michaelis-Menten kinetics we determined the enzymes affinity to substrate (Km) and mineralization potential of heterotrophic microorganisms (Vmax) 1) for three hydrolytic enzymes: β-1,4-glucosidase, N-acetyl- β -D-glucosaminidase and phosphatase by the application of fluorogenically labeled substrates and 2) for mineralization of 14C-labeled glucose by substrate-dependent respiratory response. Here we show that the amount of available substrate is responsible for temperature sensitivity of hydrolysis of polymers in soil, whereas monomers oxidation to CO2 does not depend on substrate amount and is mainly temperature governed. We also found that substrate affinity of enzymes (which is usually decreases with the temperature) differently responded to warming for the process of depolymerisation versus monomers oxidation. We suggest the mechanism to temperature acclimation based on different temperature sensitivity of enzymes kinetics for hydrolysis of polymers and for monomers oxidation.

  3. Monolayer Contact Doping from a Silicon Oxide Source Substrate.

    PubMed

    Ye, Liang; González-Campo, Arántzazu; Kudernac, Tibor; Núñez, Rosario; de Jong, Michel; van der Wiel, Wilfred G; Huskens, Jurriaan

    2017-04-03

    Monolayer contact doping (MLCD) is a modification of the monolayer doping (MLD) technique that involves monolayer formation of a dopant-containing adsorbate on a source substrate. This source substrate is subsequently brought into contact with the target substrate, upon which the dopant is driven into the target substrate by thermal annealing. Here, we report a modified MLCD process, in which we replace the commonly used Si source substrate by a thermally oxidized substrate with a 100 nm thick silicon oxide layer, functionalized with a monolayer of a dopant-containing silane. The thermal oxide potentially provides a better capping effect and effectively prevents the dopants from diffusing back into the source substrate. The use of easily accessible and processable silane monolayers provides access to a general and modifiable process for the introduction of dopants on the source substrate. As a proof of concept, a boron-rich carboranyl-alkoxysilane was used here to construct the monolayer that delivers the dopant, to boost the doping level in the target substrate. X-ray photoelectron spectroscopy (XPS) showed a successful grafting of the dopant adsorbate onto the SiO2 surface. The achieved doping levels after thermal annealing were similar to the doping levels acessible by MLD as demonstrated by secondary ion mass spectrometry measurements. The method shows good prospects, e.g. for use in the doping of Si nanostructures.

  4. Substrate use and selection in sympatric intertidal hermit crab species.

    PubMed

    Turra, A; Denadai, M R

    2002-02-01

    Coexisting hermit crabs may competitively interact for shells and microhabitats, mainly when shell availability is habitat-related. Three species of Clibanarius (C. antillensis, C. sclopetarius, and C. vittatus) coexist in the intertidal region of Pernambuco Islet, Araçá Region, São Sebastião Channel, southeastern Brazil. This study evaluated crab preferences for four substrate types used by these species in nature (rocky shore, pebbles, sand, and mud) in allopatric (single species) and sympatric (three species) treatments in simulations of high tide and low tide. The substrate preference of the three hermit crabs did not vary between low and high tide situations. At low tide the crabs either moved into holes in the highly complex rocky substrate or buried themselves in mud. Substrate selection may explain the patterns of substrate use in nature only for C. vittatus. Clibanarius antillensis and C. sclopetarius showed closer similarities in the pattern of substrate selection in the sympatric treatment with the substrate use in nature than in allopatric treatment, indicating a positive influence (dependence) of the presence of one species on the presence of another. Use of sub-optimal substrates, mainly by C. antillensis, may be caused by other factors such as its low desiccation tolerances. If competition for space takes place among these species, it would be more intense between C. sclopetarius and C. vittatus given their higher overlap in substrate preference than between them and C. antillensis.

  5. Sol-gel derived ceramic electrolyte films on porous substrates

    SciTech Connect

    Kueper, T.W.

    1992-05-01

    A process for the deposition of sol-gel derived thin films on porous substrates has been developed; such films should be useful for solid oxide fuel cells and related applications. Yttria-stabilized zirconia films have been formed from metal alkoxide starting solutions. Dense films have been deposited on metal substrates and ceramic substrates, both dense and porous, through dip-coating and spin-coating techniques, followed by a heat treatment in air. X-ray diffraction has been used to determine the crystalline phases formed and the extent of reactions with various substrates which may be encountered in gas/gas devices. Surface coatings have been successfully applied to porous substrates through the control of substrate pore size and deposition parameters. Wetting of the substrate pores by the coating solution is discussed, and conditions are defined for which films can be deposited over the pores without filling the interiors of the pores. Shrinkage cracking was encountered in films thicker than a critical value, which depended on the sol-gel process parameters and on the substrate characteristics. Local discontinuities were also observed in films which were thinner than a critical value which depended on the substrate pore size. A theoretical discussion of cracking mechanisms is presented for both types of cracking, and the conditions necessary for successful thin formation are defined. The applicability of these film gas/gas devices is discussed.

  6. Polarimetric studies of polyethylene terephtalate flexible substrates

    NASA Astrophysics Data System (ADS)

    Stchakovsky, M.; Garcia-Caurel, E.; Warenghem, M.

    2008-12-01

    Polymer sheets are currently used worldwide in a wide range of applications. The manufacturing process of these sheets involves extruding machines that stretch the material in both lateral and longitudinal directions with respect to the machine direction, thus inducing birefringence. In most cases, the film obtained is optically biaxial. Polarimetric spectroscopy (Ellipsometry and Mueller Matrix) combined with conoscopic observation are the methods of choice to study these properties. In this work we report an analysis of commercially available polyethylene terephtalate (PET) films used as substrate for food packaging as well as for embedded electronic devices such as solar cells or flexible displays. Initial observation of these films through polarizing microscope in conoscopic mode reveals first the trace of optical axis plane with respect to the film surface and second, whether the optical axis is acute or not. This preliminary study allows optimal sample positioning for further polarimetric studies. The measurements and modelling are done in both reflection and transmission mode on several spectroscopic polarimetric setups from UV to NIR. The models give as a main result, the dielectric tensor of the film as well as its orientation with respect to the laboratory reference frame.

  7. Amylase activity in substrate deficiency aerobic granules.

    PubMed

    Lee, Chuen-Chi; Lee, Duu-Jong; Lai, Juin-Yih

    2009-01-01

    Immunohistochemical staining was applied together with the multicolor fluorescent scheme to demonstrate the amylase activity for polysaccharide hydrolysis in stored or starved aerobic granules that are in substrate deficiency. If sufficient nutrients were present, alpha-amylase and beta-amylase were found close to the surface layer of the original granules. Following storage or starvation during which most external nutrients were depleted, the alpha-amylase and beta-amylase were distributed over the entire granule interior, suggesting endogenous respiration at the core of the granule. In particular, the fluorescent intensities of alpha-amylase and beta-amylase were enriched 5-20 microm from the edge of the internal cavity, suggesting the strong correlation between polysaccharide hydrolysis and the formation of interior cavities. The secreted amylase was located near the living cells, suggesting that the polysaccharide hydrolysis is restricted to local environment that occurs near the functional strains. Internal hydrolysis within the core, for the case of both proteins and polysaccharides should correspond in principle to the loss of granule stability.

  8. Regulation of substrate use during the marathon.

    PubMed

    Spriet, Lawrence L

    2007-01-01

    The energy required to run a marathon is mainly provided through oxidative phosphorylation in the mitochondria of the active muscles. Small amounts of energy from substrate phosphorylation are also required during transitions and short periods when running speed is increased. The three inputs for adenosine triphosphate production in the mitochondria include oxygen, free adenosine diphosphate and inorganic phosphate, and reducing equivalents. The reducing equivalents are derived from the metabolism of fat and carbohydrate (CHO), which are mobilised from intramuscular stores and also delivered from adipose tissue and liver, respectively. The metabolism of fat and CHO is tightly controlled at several regulatory sites during marathon running. Slower, recreational runners run at 60-65% maximal oxygen uptake (VO(2max)) for approximately 3:45:00 and faster athletes run at 70-75% for approximately 2:45:00. Both groups rely heavily on fat and CHO fuels. However, elite athletes run marathons at speeds requiring between 80% and 90% VO(2max), and finish in times between 2:05:00 and 2:20:00. They are highly adapted to oxidise fat and must do so during training. However, they compete at such high running speeds, that CHO oxidation (also highly adapted) may be the exclusive source of energy while racing. Further work with elite athletes is needed to examine this possibility.

  9. Exploring the neural substrates of misinformation processing.

    PubMed

    Gordon, Andrew; Brooks, Jonathan C W; Quadflieg, Susanne; Ecker, Ullrich K H; Lewandowsky, Stephan

    2017-10-04

    It is well known that information that is initially thought to be correct but then revealed to be false, often continues to influence human judgement and decision making despite people being aware of the retraction. Yet little research has examined the underlying neural substrates of this phenomenon, which is known as the 'continued influence effect of misinformation' (CIEM). It remains unclear how the human brain processes critical information that retracts prior claims. To address this question in further detail, 26 healthy adults underwent functional magnetic resonance imaging (fMRI) while listening to brief narratives which either involved a retraction of prior information or not. Following each narrative, subjects' comprehension of the narrative, including their inclination to rely on retracted information, was probed. As expected, it was found that retracted information continued to affect participants' narrative-related reasoning. In addition, the fMRI data indicated that the continued influence of retracted information may be due to a breakdown of narrative-level integration and coherence-building mechanisms implemented by the precuneus and posterior cingulate gyrus. Copyright © 2017. Published by Elsevier Ltd.

  10. Spreading of Emulsions on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Mohammad Karim, Alireza; Kavehpour, Pirouz

    2012-11-01

    The wettability of emulsions is an important factor with explicit influence in an extensive variety of industrial applications ranging from the petroleum to food industries. Surprisingly, there is no comprehensive study of emulsion spreading to date; this is due to the complexity of the structure of the emulsions and non-homogeneity of the dispersed phase bubbles in size as well as distribution through the emulsion. The spreading of water/silicone oil emulsions on glass substrates was investigated. The emulsions were prepared with varying volume fractions of water dispersed in silicone oil, with addition of small amounts of surfactant to stabilize the emulsion structure. The time dependent variation of dynamic contact angle, base diameter, and the spreading rate of the droplets of an emulsion are different from a pure substance. The effect of water/silicone oil weight percentage as well as the droplet size and dispersed phase bubble size were also investigated. The weight percentage of water/silicone oil emulsion and droplet size did not have significant influence on the spreading dynamics; however the dispersed phase drop size affected the spreading dynamics substantially.

  11. Capillary forces between chemically different substrates.

    PubMed

    De Souza, E J; Brinkmann, M; Mohrdieck, C; Crosby, A; Arzt, E

    2008-09-16

    Motivated by experimental results, we present numerical and analytical calculations of the capillary force exerted by a capillary bridge spanning the gap between two parallel flat plates of asymmetric wettability. Depending on whether the sum of the two contact angles is smaller or larger than 180 degrees, the capillary force is either attractive or repulsive at small separations D between the plates. In either cases the magnitude of the force diverges as D approaches zero. The leading order of this divergence is captured by an analytical expression deduced from the geometry of the meniscus of a flat capillary bridge. The results for substrates with different wettability reveal an interesting behavior: with the sum of the contact angles fixed, the magnitude of the capillary force and the rupture separation decreases as the asymmetry in contact angles is increased. In addition, we present the rupture separation, i.e., the maximal extension of a capillary bridge, as a function of the contact angles. Our results provide an extensive picture of surface wettability effects on capillary adhesion.

  12. Thin film flows over Structured Substrates

    NASA Astrophysics Data System (ADS)

    Oron, Alex; Mukhopadhyay, Shomeek; Behringer, Robert

    2006-11-01

    The dynamics of liquids over patterned substrates has been of tremendous interest because of applications in microfluidics and in creating specially engineered `non -- stick' surfaces. We study both experimentally and numerically, the limiting case of completely wetting silicone oil (PDMS) on a silicone wafer on which is deposited a `step like' precursor layer of the oil. Step like precursors of PDMS are deposited ranging in viscosity from 50 centistokes to 10000 centistokes. Silicone oil is driven up an inclined plane against gravity by imposing a temperature gradient. As the contact line emerges from the reservoir it shows a `hyberbolic tamgent' shape near the step and the flat film near the front is non trivially modified in the presence of the step. We describe the formation and evolution of the perturbed contact line in the `lubrication theory' approximation. In this particular case the flow field is analyzed in three separate regions and then `matched' across the step. The presence of the `hyberbolic tangent' shape is markedly different from other corner flow problems in thin film flows.

  13. Dropwise condensation on a cold gradient substrate

    NASA Astrophysics Data System (ADS)

    Macner, Ashley; Daniel, Susan; Steen, Paul

    2012-11-01

    Distributions of drops that arise from dropwise condensation evolve by nucleation, growth, and coalescence of drops. An understanding of how surface-energy gradients applied to the substrate affect drop growth and coalescence is needed for design of effective surfaces for large-scale dropwise condensation. Transient dropwise condensation from a vapor phase onto a cold and chemically treated surface is reported. The surfaces were treated to deliver either a uniform contact-angle or a gradient of contact-angles by silanization. The time evolution of drop-size and number-density distributions is reported. For a typical condensation experiment, the drop distributions advance through two stages: an increase in drop density as a result of nucleation and a decrease in drop density as a result of larger scale coalescence events. Because the experiment is transient in nature, the shape of the distribution can be used to predict the number of drop generations and their stage of development. Preliminary results for gradient surfaces will be discussed and compared against observations of behavior on uniformly coated surfaces. NASA Space Technology Research Fellowship (NSTRF).

  14. Neural substrates underlying delusions in schizophrenia

    PubMed Central

    Zhu, Jiajia; Zhuo, Chuanjun; Liu, Feng; Xu, Lixue; Yu, Chunshui

    2016-01-01

    Delusions are cardinal positive symptoms in schizophrenia; however, the neural substrates of delusions remain unknown. In the present study, we investigated the neural correlates of delusions in schizophrenia using multi-modal magnetic resonance imaging (MRI) techniques. Diffusion, structural and perfusion MRIs were performed in 19 schizophrenia patients with severe delusions, 30 patients without delusions and 30 healthy controls. Fractional anisotropy (FA), gray matter volume (GMV) and cerebral blood flow (CBF) were voxel-wisely compared among the three groups. Although patients without delusions exhibited decreased FA in white matter regions and decreased GMV in gray matter regions relative to controls, patients with severe delusions demonstrated comparable FA in all of these white matter regions and similar GMV in most of these gray matter regions. Both patient subgroups had less GMV in the amygdala and anterior cingulate cortex than controls. Although two patient subgroups showed consistent CBF changes relative to controls, only CBF in the anterior cingulate cortex was lower in patients with severe delusions than in patients without delusions. These findings suggest that schizophrenia patients with severe delusions have relatively normal structural integrity. Importantly, the excessively reduced perfusion in the anterior cingulate cortex may be associated with the development of delusions in schizophrenia. PMID:27651212

  15. Single crystal complex oxide on flexible substrate

    NASA Astrophysics Data System (ADS)

    Bakaul, Saidur; Serrao, Claudy; Lee, Oukjae; Salahuddin, Sayeef

    Flexible ferroelectrics are needed for various applications such as biocompatible energy harvesting and flexible memory. In this sector, most of the current research is focused on organic piezoelectric materials which have advantage of flexibility but suffers severely from poor energy conversion and generation efficiency. On the contrary, owing to very high electromechanical coupling factor (representing energy conversion efficiency) complex oxides are the best choices as energy harvesting and transduction elements, especially for transforming mechanical energies into electronic energy. Still their usage in energy harvesting is very limited mainly due to the stringent growth conditions of single crystals, high temperature needed for crystallization and lack of flexibility and stretchability. We have shown that single crystal Pb0.8Zr0.2TiO3 can be epitaxially transferred on flexible plastic substrate. The transferred PZT shows 70 uC/cm2 remnant polarization and dielectric constant over 100 even when it is bent. These results suggest the possibility of single crystal complex oxide devices on flexible platform.

  16. Neural substrates of trait ruminations in depression

    PubMed Central

    Mandell, Darcy; Siegle, Greg; Shutt, Luann; Feldmiller, Josh; Thase, Michael E.

    2014-01-01

    Rumination in depression is a risk factor for longer, more intense, and harder-to-treat depressions. But there appear to be multiple types of depressive rumination – whether they all share these vulnerability mechanisms, and thus would benefit from the same types of clinical attention is unclear. In the current study, we examined neural correlates of empirically-derived dimensions of trait rumination in 35 depressed participants. These individuals and 29 never-depressed controls completed 17 self-report measures of rumination and an alternating emotion-processing/executive-control task during functional magnetic resonance imaging (fMRI) assessment. We examined associations of regions of interest—the amygdala and other cortical regions subserving a potential role in deficient cognitive control and elaborative emotion-processing—with trait rumination. Rumination of all types was generally associated with increased sustained amygdala reactivity. When controlling for amygdala reactivity, distinct activity patterns in hippocampus were also associated with specific dimensions of rumination. We discuss the possibly utility of targeting more basic biological substrates of emotional reactivity in depressed patients who frequently ruminate. PMID:24661157

  17. Mechanisms of fibrinogen adsorption at solid substrates.

    PubMed

    Adamczyk, Zbigniew; Bratek-Skicki, Anna; Żeliszewska, Paulina; Wasilewska, Monika

    2014-01-01

    The aim of this work was to critically review recent results pertinent to fibrinogen adsorption at solid/electrolyte interfaces with the emphasis focused on a quantitative analysis of these processes in terms of the electrostatic interactions. Accordingly, in the first part, the primary chemical structure of fibrinogen is analyzed. Physicochemical data pertinent to the bulk properties derived from hydrodynamic, dynamic light scattering and micro-electrophoretic measurements aided by theoretical modeling are discussed. Possible conformations and the effective charge distribution over the fibrinogen molecule for various pH an ionic strength are defined, especially the semi-collapsed conformation prevailing at physiological conditions. Adsorption kinetics of fibrinogen at hydrophilic and hydrophobic (polymer modified) substrates determined by various techniques is described. Adsorption at polymeric carrier particles, pertinent to immunological assays, studied in terms of electrokinetic and concentration depletion methods, are also considered. The reversibility of adsorption, fibrinogen molecule orientations and maximum coverages are thoroughly discussed. The stability of fibrinogen monolayers formed at these carrier particles in respect to pH and ionic strength cyclic changes is also discussed. In the final section interactions and deposition of model colloid particles on fibrinogen monolayers are analyzed which allows one to derive valuable information about molecule orientations. Based on the physicochemical data, adsorption kinetics and colloid particle deposition measurements, probable adsorption mechanisms of fibrinogen on solid/electrolyte interfaces are defined.

  18. Kink's dynamics for a deformable substrate potential

    NASA Astrophysics Data System (ADS)

    Tchofo Dinda, P.; Willis, C. R.

    1994-01-01

    We study the static and dynamic properties of a kink in a chain of harmonically coupled atoms subjected to a deformable double-well substrate potential. We treat intrinsically the lattice discreteness without approximation and show that in some deformation-parameter ranges each period of the PN (Peierls-Nabarro) potential consists of two wells whose minima are located respectively on a lattice site and midway between two adjacent sites of the chain. In some other parameter ranges each period of the PN potential posseses a single well whose minimum is located either on a lattice site or midway between two adjacent lattice sites. We examine the kink's dynamics by using a multiple-collective-variable treatment, that is, we derive the exact equations of motion for the collective variables X and Y - which describe respectively the center-of-mass mode and the internal mode of the kink. We numerically solve the collective variable equations of motion for the trapped and untrapped regimes of the discrete-kink motion, and show that the presence of a nonlinear internal mode makes a contribution of particular importance in the discrete-kink's dynamics. Indeed, we show that during its untrapped regime, the discrete kink can undergo one or more temporary trappings and even a reflection back over several PN wells, and relate such behaviours to the effects of the excitations of the internal mode of the kink.

  19. Specular steel surfaces for solar mirror substrates

    NASA Astrophysics Data System (ADS)

    Tracy, C. E.; Gross, G. E.

    1988-04-01

    The long-range objective is to develop a process for making a silvered stainless steel mirror that has the optical performance and service life of a mirror coupled with the mechanical durability, structural strength, and flexibility of sheet steel. Such reflectors are expected to minimize the cost handling, shipping, and fabrication into concentrators. Applications for helistats are assumed to require a lifetime average reflectance of 90 percent in a full-cone aperture angle of 8 mrad. Specifically, this work is designed to produce thin metal membranes with sufficiently fine surface finishes to serve as substrates for direct silver deposition or indirectly for silvered polymer films or silvered sol-gel coatings in heliostat, parabolic trough, and dish applications. Our focus is on the effect of the sheet metal finish on specularity and the ways to obtain the optimum surface finish by conventional manufacturing processes. This report addresses the relationship of optical quality to surface finish and the results of a cooperative research venture with a commercial sheet manufacturer to produce specular stainless steel surfaces by cold-rolling with highly polished rollers.

  20. Bimodal lipid substrate dependence of phosphatidylinositol kinase.

    PubMed

    Ganong, B R

    1990-07-24

    Phosphatidylinositol (PI) kinase activity was solubilized from rat liver microsomes and partially purified by chromatography on hydroxyapatite and Reactive Green 19-Superose. Examination of the ATP dependence using a mixed micellar assay gave a Km of 120 microM. The dependence of reaction rate on PI was more complicated. PI kinase bound a large amount of Triton X-100, and as expected for a micelle-associated enzyme utilizing a micelle-associated lipid substrate, the reaction rate was dependent on the micellar mole fraction, PI/(PI + Triton X-100), with a Km of 0.02 (unitless). Activity showed an additional dependence on bulk PI concentration at high micelle dilution. These results demonstrated two kinetically distinguishable steps leading to formation of a productive PI/enzyme(/ATP) complex. The rate of the first step, which probably represents exchange of PI from the bulk micellar pool into enzyme-containing micelles, depends on bulk PI concentration. The rate of the second step, association of PI with enzyme within a single micelle, depends on the micellar mole fraction of PI. Depression of the apparent Vmax at low ionic strength suggested that electrostatic repulsion between negatively charged PI/Triton X-100 mixed micelles inhibits PI exchange, consistent with a model in which intermicellar PI exchange depends on micellar collisions.

  1. Crystal Structure and Substrate Specificity of D-Galactose-6-Phosphate Isomerase Complexed with Substrates

    PubMed Central

    Lee, Jung-Kul; Pan, Cheol-Ho

    2013-01-01

    D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays. PMID:24015281

  2. Effect of substrate bias on the structural and electrical properties of sputtered Mo thin films on flexible substrates.

    PubMed

    Xu, Jiaxiong

    2016-07-04

    The metal molybdenum (Mo) thin films deposited on flexible substrates can act as the contact electrode of flexible Cu(In,Ga)Se2 or Cu2ZnSn(S,Se)4 solar cells. In this work, in order to enhance the structural and electrical characteristics of flexible Mo thin films, a negative substrate bias was applied during the direct current sputtering of Mo thin films. The flexible substrates used for growing the Mo films were stainless steel foils and polyimides. The characteristics of Mo thin films were studied by x-ray diffraction and sheet resistance measurements. The measured results reveal that an optimal value of negative substrate bias can be found for improving the electrical and structural characteristics of Mo thin films on flexible substrates. The minimum sheet resistances of Mo thin films are 2.50 Ω/sq and 2.73 Ω/sq for the stainless steel foil and polyimide substrates, respectively.

  3. Method of making carbon nanotubes on a substrate

    DOEpatents

    Gao, Yufei; Liu, Jun

    2006-03-14

    The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

  4. Oviposition Substrate of the Mountain Fly Drosophila nigrosparsa (Diptera: Drosophilidae).

    PubMed

    Kinzner, Martin-Carl; Tratter, Magdalena; Bächli, Gerhard; Kirchmair, Martin; Kaufmann, Rüdiger; Arthofer, Wolfgang; Schlick-Steiner, Birgit C; Steiner, Florian M

    2016-01-01

    The survival of insect larvae often depends on the mother's choice of oviposition substrate, and thus, this choice is an essential part of an insect species' ecology. Especially species with narrow substrate preferences may suffer from changes in substrate availability triggered by, for example, climate change. Recent climate warming is affecting species directly (e.g., physiology) but also indirectly (e.g., biological interactions) leading to mismatching phenologies and distributions. However, the preferred oviposition substrate is still unknown for many drosophilid species, especially for those at higher elevations. In this study, we investigated the oviposition-substrate preference of the montane-alpine fly Drosophila nigrosparsa in rearing and multiple-choice experiments using natural substrates in the laboratory. Insect emergence from field-collected substrates was tested. More than 650 insects were reared from natural substrates, among them 152 drosophilids but no individual of D. nigrosparsa. In the multiple-choice experiments, D. nigrosparsa preferred ovipositing on mushrooms (> 93% of eggs); additionally, a few eggs were laid on berries but none on other substrates such as cow faeces, rotten plant material, and soil. The flies laid 24 times more eggs per day when mushrooms were included in the substrates than when they were excluded. We infer that D. nigrosparsa is a mushroom breeder with some variation in oviposition choice. The flies favoured some mushrooms over others, but they were not specialised on a single fungal taxon. Although it is unclear if and how climate change will affect D. nigrosparsa, our results indicate that this species will not be threatened by oviposition-substrate limitations in the near future because of the broad altitudinal distribution of the mushrooms considered here, even if the flies will have to shift upwards to withstand increasing temperatures.

  5. Oviposition Substrate of the Mountain Fly Drosophila nigrosparsa (Diptera: Drosophilidae)

    PubMed Central

    Tratter, Magdalena; Bächli, Gerhard; Kirchmair, Martin; Kaufmann, Rüdiger; Arthofer, Wolfgang; Schlick-Steiner, Birgit C.; Steiner, Florian M.

    2016-01-01

    The survival of insect larvae often depends on the mother’s choice of oviposition substrate, and thus, this choice is an essential part of an insect species’ ecology. Especially species with narrow substrate preferences may suffer from changes in substrate availability triggered by, for example, climate change. Recent climate warming is affecting species directly (e.g., physiology) but also indirectly (e.g., biological interactions) leading to mismatching phenologies and distributions. However, the preferred oviposition substrate is still unknown for many drosophilid species, especially for those at higher elevations. In this study, we investigated the oviposition-substrate preference of the montane-alpine fly Drosophila nigrosparsa in rearing and multiple-choice experiments using natural substrates in the laboratory. Insect emergence from field-collected substrates was tested. More than 650 insects were reared from natural substrates, among them 152 drosophilids but no individual of D. nigrosparsa. In the multiple-choice experiments, D. nigrosparsa preferred ovipositing on mushrooms (> 93% of eggs); additionally, a few eggs were laid on berries but none on other substrates such as cow faeces, rotten plant material, and soil. The flies laid 24 times more eggs per day when mushrooms were included in the substrates than when they were excluded. We infer that D. nigrosparsa is a mushroom breeder with some variation in oviposition choice. The flies favoured some mushrooms over others, but they were not specialised on a single fungal taxon. Although it is unclear if and how climate change will affect D. nigrosparsa, our results indicate that this species will not be threatened by oviposition-substrate limitations in the near future because of the broad altitudinal distribution of the mushrooms considered here, even if the flies will have to shift upwards to withstand increasing temperatures. PMID:27788257

  6. Hydrological performance of dual-substrate-layer green roofs using porous inert substrates with high sorption capacities.

    PubMed

    Wang, Xiaoou; Tian, Yimei; Zhao, Xinhua; Peng, Chenrui

    2017-06-01

    Given that the common medium in existing green roofs is a single layer composed of organic and inorganic substrates, seven pilot-scale dual-substrate-layer extensive green roofs (G1-G7), which include nutrition and adsorption substrate layers, were constructed in this study. The effectiveness of porous inert substrates (activated charcoal, zeolite, pumice, lava, vermiculite and expanded perlite) used as the adsorption substrate for stormwater retention was investigated. A single-substrate-layer green roof (G8) was built for comparison with G1-G7. Despite the larger total rainfall depth (mm) of six types of simulated rains (43.2, 54.6, 76.2, 87.0, 85.2 and 86.4, respectively), the total percent retention of G1-G7 varied between 14% and 82% with an average of 43%, exhibiting better runoff-retaining capacity than G8 based on the maximum potential rainfall storage depth per unit height of adsorption substrate. Regression analysis showed that there was a logarithmic relationship between cumulative rainfall depth with non-zero runoff and stormwater retention for G1-G4 and a linear relationship for G5-G8. To enhance the water retention capacity and extend the service life of dual-substrate-layer extensive green roofs, the mixture of activated charcoal and/or pumice with expanded perlite and/or vermiculite is more suitable as the adsorption substrate than the mixture containing lava and/or zeolite.

  7. Development of SERS substrates for immunoassay applications

    NASA Astrophysics Data System (ADS)

    Celik, Okkes; Kahraman, Mehmet

    2016-03-01

    Surface-enhanced Raman scattering (SERS) is an emerging technique for the detection and identification of biological structures. SERS is based on immunoassay methods are mostly used for the specific detection and identification of bacteria. In this study, SERS substrates are developed with deposition of synthesized spherical 13 nm gold nanoparticles (AuNPs) and 50 nm silver nanoparticles (AgNPs) on regular glass slides with convective assembly method for SERS based immunoassay for the detection and identification of bacteria. The synthesized NPs are characterized by UV-vis absorption spectroscopy, dynamic light scattering (DLS) and atomic force microscopy (AFM). Colloidal suspensions are concentrated by centrifugation to obtain thin films by the deposition of NPs on a regular glass slide with the convective assembly. The experimental parameters for the convective assembly are optimized by changing of NP concentration, stage velocity and NPs volume dropped between two glass slides. Structural characterization of thin films is performed by AFM and SEM. SERS is also used for the optical characterization of the prepared thin films of NPs. In this study, 4- aminothiophenol (4-ATP) is used as probe molecules to evaluate SERS activity of the thin films depending on the type and concentration of NPs. The results demonstrate that, SERS performances of the thin films are dependent on not only the type of NPs but also it depends on the concentration of NPs which forms thin films. The thin film having highest SERS activity could be used for the SERS-based immunoassays for the detection and identification of bacteria.

  8. Psychoanatomical substrates of Bálint's syndrome

    PubMed Central

    Rizzo, M; Vecera, S

    2002-01-01

    Objectives: From a series of glimpses, we perceive a seamless and richly detailed visual world. Cerebral damage, however, can destroy this illusion. In the case of Bálint's syndrome, the visual world is perceived erratically, as a series of single objects. The goal of this review is to explore a range of psychological and anatomical explanations for this striking visual disorder and to propose new directions for interpreting the findings in Bálint's syndrome and related cerebral disorders of visual processing. Methods: Bálint's syndrome is reviewed in the light of current concepts and methodologies of vision research. Results: The syndrome affects visual perception (causing simultanagnosia/visual disorientation) and visual control of eye and hand movement (causing ocular apraxia and optic ataxia). Although it has been generally construed as a biparietal syndrome causing an inability to see more than one object at a time, other lesions and mechanisms are also possible. Key syndrome components are dissociable and comprise a range of disturbances that overlap the hemineglect syndrome. Inouye's observations in similar cases, beginning in 1900, antedated Bálint's initial report. Because Bálint's syndrome is not common and is difficult to assess with standard clinical tools, the literature is dominated by case reports and confounded by case selection bias, non-uniform application of operational definitions, inadequate study of basic vision, poor lesion localisation, and failure to distinguish between deficits in the acute and chronic phases of recovery. Conclusions: Studies of Bálint's syndrome have provided unique evidence on neural substrates for attention, perception, and visuomotor control. Future studies should address possible underlying psychoanatomical mechanisms at "bottom up" and "top down" levels, and should specifically consider visual working memory and attention (including object based attention) as well as systems for identification of object

  9. Superhydrophobic composite films produced on various substrates.

    PubMed

    Manoudis, Panagiotis N; Karapanagiotis, Ioannis; Tsakalof, Andreas; Zuburtikudis, Ioannis; Panayiotou, Costas

    2008-10-07

    Hydrophilic silica (SiO2) nanoparticles were dispersed in solutions of poly(methyl methacrylate) (PMMA) and in solutions of a commercial poly(alkyl siloxane) (Rhodorsil 224), and the suspensions were sprayed on glass surfaces. The effect of the particle concentration on the hydrophobic character of PMMA-SiO2 and Rhodorsil-SiO2 films was investigated and showed the following: (i) Static contact angles (theta s), measured on surfaces that were prepared from dilute dispersions (particle concentration <1% w/v), increase rapidly with particle concentration and reach maximum values (154 and 164 degrees for PMMA-SiO2 and siloxane-SiO2, respectively). Further increases in particle concentration do not have any effect on theta s. (ii) The effect of particle concentration on the contact angle hysteresis (thetaAlpha - thetaR) is more complicated: as the particle concentration increases, we first notice an increase in hysteresis, which then decreases and finally becomes constant at elevated particle concentrations. The lowest thetaAlpha - thetaR values were 5 degrees for PMMA-SiO2 and 3 degrees for siloxane-SiO2, respectively. (iii) SEM and AFM images show that a two-length-scale hierarchical structure is formed on the surface of the superhydrophobic films. It is demonstrated that superhydrophobicity can be achieved using various hydrophilic nanoparticles (alumina and tin oxide nanoparticles were successfully tested) and that the substrate has almost no effect on the hydrophobic character of the applied coatings, which were produced on silicon, concrete, aluminum, silk, wood, marble, and of course glass. The results are discussed in light of Wenzel and Cassie-Baxter models.

  10. Zeta potential orientation dependence of sapphire substrates.

    PubMed

    Kershner, Ryan J; Bullard, Joseph W; Cima, Michael J

    2004-05-11

    The zeta potential of planar sapphire substrates for three different crystallographic orientations was measured by a streaming potential technique in the presence of KCl and (CH3)4NCl electrolytes. The streaming potential was measured for large single crystalline C-plane (0001), A-plane (1120), and R-plane (1102) wafers over a full pH range at three or more ionic strengths ranging from 1 to 100 mM. The roughness of the epi-polished wafers was verified using atomic force microscopy to be on the order of atomic scale, and X-ray photoelectron spectroscopy (XPS) was used to ensure that the samples were free of silica and other contaminants. The results reveal a shift in the isoelectric point (iep) of the three samples by as much as two pH units, with the R-plane surface exhibiting the most acidic behavior and the C-plane samples having the highest iep. The iep at all ionic strengths was tightly centered around a single pH for each wafer. These values of iep are substantially different from the range of pH 8-10 consistently reported in the literature for alpha-Al2O3 particles. Particle zeta potential measurements were performed on a model powder using phase analysis light scattering, and the iep was confirmed to occur at pH 8. Modified Auger parameters (MAP) were calculated from XPS spectra of a monolayer of iridium metal deposited on the sapphire by electron beam deposition. A shift in MAP consistent with the observed differences in iep of the surfaces confirms the effect of surface structure on the transfer of charge between the Ir and sapphire, hence accounting for the changes in acidity as a function of crystallographic orientation.

  11. Growth of marine fungi on polymeric substrates.

    PubMed

    Wang, Yanming; Barth, Dorothee; Tamminen, Anu; Wiebe, Marilyn G

    2016-01-16

    Marine fungi are a diverse group of opportunistic and obligate organisms isolated from marine environments. These fungi are now often included in screens for novel metabolites, while less attention has been given to their production of hydrolytic enzymes. Most enzymes derived from marine microorganisms have been obtained from marine bacteria. The enzymes produced by marine fungi may have different properties than those derived from bacteria or from terrestrial fungi. Here we assess the growth of six filamentous marine fungi on a wide range of polymeric substrates as an indication of their general capacity to produce hydrolytic enzymes. Calcarisporium sp. KF525, Tritirachium sp. LF562, Bartalinia robillardoides LF550, Penicillium pinophilum LF458, Scopulariopsis brevicaulis LF580 and Pestalotiopsis sp. KF079 all grew on both casein and gelatin as N-source, indicating secretion of proteases. All species also grew on starch, laminarin, xylan, pectin and oil, indicating production of amylases, glucanases, xylanases, pectinases and lipases. Growth on cellulose occurred but was weaker than on xylan. All strains also grew to some extent on sulphated arabinogalactan, although only LF562 could utilise arabinose. Four strains grew on the sulphated ulvans, whereas only KF525 grew on agar or carrageenan. KF525 and LF562 showed limited growth on alginate. Although fucose was used as carbon source by several species, fucoidan did not support biomass production. Marine fungi could be excellent sources of a wide range of hydrolytic enzymes, including those able to hydrolyse various seaweed polymers. Although the native hosts may secrete only small amounts of these enzymes, the genes may provide a rich source of novel enzymes.

  12. Neural substrates of time perception and impulsivity.

    PubMed

    Wittmann, Marc; Simmons, Alan N; Flagan, Taru; Lane, Scott D; Wackermann, Jiří; Paulus, Martin P

    2011-08-11

    Several studies provide empirical evidence for the association between impulsivity and time perception. However, little is known about the neural substrates underlying this function. This investigation examined the influence of impulsivity on neural activation patterns during the encoding and reproduction of intervals with durations of 3, 9 and 18s using event-related functional magnetic resonance imaging (fMRI). Twenty-seven subjects participated in this study, including 15 high impulsive subjects that were classified based on their self-rating. FMRI activation during the duration reproduction task was correlated with measures of two self-report questionnaires related to the concept of impulsivity (Barratt Impulsiveness Scale, BIS; Zimbardo Time Perspective Inventory, ZTPI). Behaviorally, those individuals who under-reproduced temporal intervals also showed lower scores on the ZTPI future perspective subscale and higher scores on the BIS. FMRI activation revealed an accumulating pattern of neural activity peaking at the end of the 9- and 18-s intervals within right posterior insula. Activations of brain regions during the reproduction phase of the timing task, such as those related to motor execution as well as to the 'core control network' - encompassing the inferior frontal and medial frontal cortices, the anterior insula as well as the inferior parietal cortex - were significantly correlated with reproduced duration, as well as with BIS and ZTPI subscales. In particular, the greater activation in these regions the shorter were the reproduced intervals, the more impulsive was an individual and the less pronounced the future perspective. Activation in the core control network, thus, may form a biological marker for cognitive time management and for impulsiveness.

  13. Neural substrates of time perception and impulsivity

    PubMed Central

    Wittmann, Marc; Simmons, Alan N.; Flagan, Taru; Lane, Scott D.; Wackermann, Jiří; Paulus, Martin P.

    2011-01-01

    Several studies provide empirical evidence for the association between impulsivity and time perception. However, little is known about the neural substrates underlying this function. This investigation examined the influence of impulsivity on neural activation patterns during the encoding and reproduction of intervals with durations of 3, 9 and 18 seconds using event-related functional magnetic resonance imaging (fMRI). Twenty-seven subjects participated in this study, including 15 high impulsive subjects that were classified based on their self-rating. FMRI activation during the duration reproduction task was correlated with measures of two self-report questionnaires related to the concept of impulsivity (Barratt Impulsiveness Scale, BIS; Zimbardo Time Perspective Inventory, ZTPI). Behaviorally, those individuals who under-reproduced temporal intervals also showed lower scores on the ZTPI future perspective subscale and higher scores on the BIS. FMRI activation revealed an accumulating pattern of neural activity peaking at the end of the 9- and 18-s interval within right posterior insula. Activations of brain regions during the reproduction phase of the timing task, such as those related to motor execution as well as to the ‘core control network’ – encompassing the inferior frontal and medial frontal cortex, the anterior insula as well as the inferior parietal cortex – were significantly correlated with reproduced duration, as well as with BIS and ZTPI subscales. In particular, the greater activation in these regions the shorter were the reproduced intervals, the more impulsive was an individual and the less pronounced the future perspective. Activation in the core control network, thus, may form a biological marker for cognitive time management and for impulsiveness. PMID:21763642

  14. Shared neural substrates of apraxia and aphasia.

    PubMed

    Goldenberg, Georg; Randerath, Jennifer

    2015-08-01

    Apraxia is regularly associated with aphasia, but there is controversy whether their co-occurrence is the expression of a common basic deficit or results from anatomical proximity of their neural substrates. However, neither aphasia nor apraxia is an indivisible entity. Both diagnoses embrace diverse manifestations that may occur more or less independently from each other. Thus, the question whether apraxia is always accompanied by aphasia may lead to conflicting answers depending on which of their manifestations are considered. We used voxel based lesion symptom mapping (VLSM) for exploring communalities between lesion sites associated with aphasia and with apraxia. Linguistic impairment was assessed by the Aachen Aphasia Test (AAT) subtests naming, comprehension, repetition, written language, and Token Test. Apraxia was examined for imitation of meaningless hand and finger postures and for pantomime of tool use. There were two areas of overlap between aphasia and apraxia. Lesions in the anterior temporal lobe interfered with pantomime of tool use and with all linguistic tests. In the left inferior parietal lobe there was a large area where lesions were associated with defective imitation of hand postures and with poor scores on written language and the Token Test. Within this large area there were also two spots in supramarginal and angular gyrus where lesions were also associated with defective pantomime. We speculate that the coincidence of language impairment and defective pantomime after anterior temporal lesions is due to impaired access to semantic memory. The combination of defective imitation of hand postures with poor scores on Token Test and written language is not easily compatible with a crucial role of parietal regions for the conversion of concepts of intended actions into motor commands. It accords better with a role of left inferior parietal lobe regions for the categorical perception of spatial relationships.

  15. Diamond LED substrate and novel quantum dots.

    PubMed

    Sung, James C; Sung, Michael

    2009-02-01

    Nitride LED (e.g., GaN) has become the mainstream of blue light source. The blue light can be converted to white light by exciting a phosphor (e.g., Nichia's YAG or Osram's TAG) with the complementary yellow emission. However, GaN is typically deposited on sapphire (Al2O3) substrates formed by crystal pulling or hexagonal (e.g., 4 H or 6 H) SiC wafers condensed from SiC vapor. In either case, the nitride lattice is ridden (e.g., 10(9)/cm2) with dislocations. The high dislocation density with sapphire is due to the large (>13%) lattice mismatch; and with hexagonal SiC, because of intrinsic defects. Cubic (beta) SiC may be deposited epitaxially using a CVD reactor onto silicon wafer by diffusing the interface and by chemical gradation. A reactive echant (e.g., hydrogen or fluorine) can be introduced periodically to gasify mis-aligned atoms. In this case, large single crystal wafers would be available for the manufacture of high bright LED with superb electro-optical efficiency. The SiC wafer may be coated with diamond film that can eliminate heat in real time. As a result of lower temperature, the nitride LED can be brighter and it will last longer. The blue light of GaN LED formed on SiC on Diamond (SiCON) LED may also be scattered by using novel quantum dots (e.g., 33 atom pairs of CdSe) to form a broad yellow light that blend in with the original blue light to form sunlight-like white light. This would be the ideal source for general illumination (e.g., for indoor) or backlighting (e.g., for LCD).

  16. Development of the Enzyme-Substrate Interactions Concept Inventory

    ERIC Educational Resources Information Center

    Bretz, Stacey Lowery; Linenberger, Kimberly J.

    2012-01-01

    Enzyme function is central to student understanding of multiple topics within the biochemistry curriculum. In particular, students must understand how enzymes and substrates interact with one another. This manuscript describes the development of a 15-item Enzyme-Substrate Interactions Concept Inventory (ESICI) that measures student understanding…

  17. Use of neem cake as an organic substrate component

    USDA-ARS?s Scientific Manuscript database

    Nursery and greenhouse growers continue to seek materials to decrease costs of plant production while maintaining environmental stewardship. Incorporation of neem cake as a substrate component could potentially impact nitrogen release as a result of altering substrate bacterial activity. The study...

  18. Substrate effects on surface plasmons in single nanoholes.

    SciTech Connect

    Shuford, K. L.; Gray, S. K.; Ratner, M. A.; Schatz, G. C.; Chemistry; ORNL; Northwestern Univ.

    2007-01-01

    Light transmission and electric field enhancement are calculated for a cylindrical aperture in a silver slab resting on a glass substrate. We find that these properties are influenced significantly by the presence of the substrate. The results suggest that variations in the local dielectric alter the properties of localized surface plasmons that drive the field enhancement and transmission.

  19. Continuous columns for determining moisture characteristic curves of soilless substrates

    USDA-ARS?s Scientific Manuscript database

    Sound water management is essential for effectively producing nursery crops. Understanding substrate water availability is a critical component to managing irrigation properly. The objective of this paper is to report a method for generating moisture characteristic curves of soilless substrate tha...

  20. High-Efficiency Solar Cells on Low-Cost Substrates

    NASA Technical Reports Server (NTRS)

    Daiello, R. V.; Robinson, P. H.

    1982-01-01

    High-efficiency solar cells made in thin epitaxial films grown on low-cost commercial silicon substrates. Cost of cells is much less than if high-quality single-crystal silicon were used for substrates and performance of cells is almost as good.