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Sample records for cumulus cells electronic

  1. Protection of cumulus cells following dehydroepiandrosterone supplementation.

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    Lin, Li-Te; Wang, Peng-Hui; Chen, San-Nung; Li, Chia-Jung; Wen, Zhi-Hong; Cheng, Jiin-Tsuey; Tsui, Kuan-Hao

    2017-02-01

    Growing studies have demonstrated that dehydroepiandrosterone (DHEA) may improve fertility outcomes in poor ovarian responders (PORs). The aim of this study was to compare clinical outcomes and cumulus cell (CC) expression before and after DHEA treatment in PORs undergoing in vitro fertilization (IVF) cycles. Six patients with poor ovarian response were enrolled in the study according to Bologna criteria. DHEA was supplied at least 2 months before patients entered into the next IVF cycle. Expression of apoptosis-related genes in CCs was determined by quantitative real-time PCR. Mitochondrial dehydrogenase activity of CCs was assessed by cell counting kit-8 assay. Metaphase II oocytes, maturation rate, embryos at Day 3, and fertilization rate significantly increased following DHEA treatment. Expression of cytochrome c, caspase 9, and caspase 3 genes in CCs were significantly reduced after DHEA therapy. Additionally, increased mitochondrial activity of CCs was observed following DHEA supplementation. DHEA supplementation may protect CCs via improved mitochondrial activity and decreased apoptosis, leading to better clinical outcomes in PORs.

  2. Rhesus monkey cumulus cells revert to a mural granulosa cell state after an ovulatory stimulus.

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    Chaffin, Charles L; Lee, Young S; VandeVoort, Catherine A; Patel, Bela G; Latham, Keith E

    2012-11-01

    Follicular somatic cells (mural granulosa cells and cumulus cells) and the oocyte communicate through paracrine interactions and through direct gap junctions between oocyte and cumulus cells. Considering that mural and cumulus cells arise through a common developmental pathway and that their differentiation is essential to reproductive success, understanding how these cells differ is a key aspect to understanding their critical functions. Changes in global gene expression before and after an ovulatory stimulus were compared between cumulus and mural granulosa cells to test the hypothesis that mural and cumulus cells are highly differentiated at the time of an ovulatory stimulus and further differentiate during the periovulatory interval. The transcriptomes of the two cell types were markedly different (>1500 genes) before an ovulatory hCG bolus but converged after ovulation to become completely overlapping. The predominant transition was for the cumulus cells to become more like mural cells after hCG. This indicates that the differentiated phenotype of the cumulus cell is not stable and irreversibly established but may rather be an ongoing physiological response to the oocyte.

  3. Cumulus Cell Expansion, Its Role in Oocyte Biology and Perspectives of Measurement: A Review

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    Nevoral J.

    2015-01-01

    Full Text Available Cumulus expansion of the cumulus-oocyte complex is necessary for meiotic maturation and acquiring developmental competence. Cumulus expansion is based on extracellular matrix synthesis by cumulus cells. Hyaluronic acid is the most abundant component of this extracellular matrix. Cumulus expansion takes place during meiotic oocyte maturation under in vivo and in vitro conditions. Quantification and measurement of cumulus expansion intensity is one possible method of determining oocyte quality and optimizing conditions for in vitro cultivation. Currently, subjective methods of expanded area and more exact cumulus expansion measurement by hyaluronic acid assessment are available. Among the methods of hyaluronic acid measurement is the use of radioactively labelled synthesis precursors. Alternatively, immunological and analytical methods, including enzyme-linked immunosorbent assay (ELISA, spectrophotometry, and high-performance liquid chromatography (HPLC in UV light, could be utilized. The high sensitivity of these methods could provide a precise analysis of cumulus expansion without the use of radioisotopes. Therefore, the aim of this review is to summarize and compare available approaches of cumulus expansion measurement, respecting special biological features of expanded cumuli, and to suggest possible solutions for exact cumulus expansion analysis.

  4. Cumulus-specific genes are transcriptionally silent following somatic cell nuclear transfer in a mouse model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study investigated whether four cumulus-specific genes: follicular stimulating hormone receptor (FSHr), hyaluronan synthase 2 (Has2), prostaglandin synthase 2 (Ptgs2) and steroidogenic acute regulator protein (Star), were correctly reprogrammed to be transcriptionally silent following somatic cell nuclear transfer (SCNT) in a murine model. Cumulus cells of C57×CBA F1 female mouse were injected into enucleated oocytes, followed by activation in 10 μmol/L strontium chloride for 5 h and subsequent in vitro culture up to the blastocyst stage. Expression of cumulus-specific genes in SCNT-derived embryos at 2-cell, 4-cell and day 4.5 blastocyst stages was compared with corresponding in vivo fertilized embryos by real-time PCR. It was demonstrated that immediately after the first cell cycle, SCNT-derived 2-cell stage embryos did not express all four cumulus-specific genes, which continually remained silent at the 4-cell and blastocyst stages. It is therefore concluded that all four cumulus-specific genes were correctly reprogrammed to be silent following nuclear transfer with cumulus donor cells in the mouse model. This would imply that the poor preimplantation developmental competence of SCNT embryos derived from cumulus cells is due to incomplete reprogramming of other embryonic genes, rather than cumulus-specific genes.

  5. Cloned calves produced by nuclear transfer from cultured cumulus cells

    Institute of Scientific and Technical Information of China (English)

    AN; Xiaorong(安晓荣); GOU; Kemian(苟克勉); ZHU; Shien(朱士恩); GUAN; Hong(关宏); HOU; Jian(侯健); LIN; Aixing(林爱星); ZENG; Shenming(曾申明); TIAN; Jianhui(田见辉); CHEN; Yongfu(陈永福)

    2002-01-01

    Short-term cultured cumulus cell lines (1-5BCC) derived from 5 individual cows were used in nuclear transfer (NT) and 1188 enucleated bovine oocytes matured in vitro were used as nuclear recipients. A total of 931 (78.4%) cloned embryos were reconstructed, of which 763 (82%) cleaved, 627 (67.3%) developed to 8-cell stage, and 275 (29.5%) reached blastocyst stage. The average cell number of blastocysts was 124±24.5 (n=20). In this study, the effects of donor cell sources, serum starvation of donor cells, time interval from fusion to activation (IFA) were also tested on cloning efficiency. These results showed that blastocyst rates of embryos reconstructed from 5 different individuals cells were significantly different among them (14.1%, 45.2%, 27.3%, 34.3%, vs 1.5%, P0.05); and that blastocyst rate (20.3%) of the group with fusion/activation interval of 2-3 h, was significantly lower than that of the 3-6 h groups (31.0%), while not significantly different among 3-4 h (P < 0.05), 4-5 h, and 5-6 h groups (P ≥ 0.05). Sixty-three thawed NT blastocysts were transferred to 31 recipient cows, of which 4 pregnancies were established and two cloned calves were given birth. These results indicate that serum starvation of cumulus cells is not a key factor for successful bovine cloning, while IFA treatment and sources of donor cells have effects on cloning efficiency.

  6. BMP15 Prevents Cumulus Cell Apoptosis Through CCL2 and FBN1 in Porcine Ovaries

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    Bo Zhai

    2013-07-01

    Full Text Available Background: Bone morphogenetic protein-15 (BMP15 is a maternal gene necessary for mammalian reproduction. BMP15 expression increased in oocytes accompanied by follicle growth and development. The function and regulation mechanism of BMP15 in porcine cumulus cell apoptosis process is still unclear now. Methods: In this study, flow cytometry (FCM was used to analyze the effects of BMP15 with different concentrations to cumulus cell apoptosis. High-throughput sequencing technology was carried out to screen regulatory genes linked closely with BMP15. In order to confirm the function of (MCP-1/CCL2 and FBN1 in cumulus cell apoptosis, RNA interference (RNAi method was used to inhibit the expression of (MCP-1/CCL2 and FBN1. Apoptosis and proliferation of cumulus cell treated with siRNA transfection technology were measured by FCM, 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide, quantitative real time-PCR (RT-qPCR and western blotting. Results: The results showed that the apoptosis levels of cumulus cell treated by BMP15 decreased significantly in a dose-dependent manner. The expression of related genes protein 1 (MCP-1/CCL2 and fibrillin1 (FBN1 were both regulated by BMP15. After transfection, the proliferation of porcine cumulus cells increased significantly and apoptosis of cumulus cells was prevented while FBN1 was silenced after BMP15 treatment. The proliferation of cumulus cells decreased significantly and apoptosis rate of cumulus cells increased significantly while CCL2 was silenced. Conclusion: The results obtained in this study firstly demonstrated that CCL2 and FBN1 are important regulatory factors of BMP15 in preventing cumulus cell apoptosis in porcine ovaries.

  7. General features of certain RNA populations from gametes and cumulus cells.

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    Payton, Rebecca R; Rispoli, Louisa A; Edwards, J Lannett

    2010-12-01

    Results described herein provide insight regarding certain features of gamete RNA and how they compare to cumulus cell RNA. In particular, 28S/18S rRNA ratio and size distribution of RNA molecules differed in total RNA from oocytes versus surrounding cumulus cells. Specifically, oocyte total RNA had a lower rRNA ratio and an increased abundance of smaller RNA sizes compared to RNA from surrounding cumulus. Extensive efforts demonstrated that observed differences were repeatable whether oocyte maturation occurred in vitro or in vivo, and were similar between the nuclear stages examined. Features of oocyte RNA were conserved across six mammalian species, yet differed from surrounding cumulus. Profiles of sperm RNA were also examined but had no discernible ribosomal RNA peaks and were conserved across four mammalian species. Because the oocyte and spermatozoon are highly specialized cells representing unique molecular entities required for proper embryo development, dissimilarities described herein likely represent real gamete versus cumulus RNA differences.

  8. PTGS2 down-regulation in cumulus cells of infertile women with endometriosis.

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    da Luz, Caroline M; da Broi, Michele G; Donabela, Flávia Cappello; Paro de Paz, Cláudia Cristina; Meola, Juliana; Navarro, Paula A

    2017-07-10

    A deleterious effect of endometriosis on oocyte quality has been proposed. Evidence suggests that cumulus cells could be used as indirect biomarkers of oocyte quality. The PTGS2 gene, which encodes cyclooxygenase 2 (COX-2), is deregulated in endometriotic lesions and plays a crucial role in the acquisition of oocyte competence. To date, research evaluating PTGS2 expression in cumulus cells of infertile patients with endometriosis has not been conducted. The aim this study was to compare the expression levels of PTGS2 in cumulus cells of infertile women, with and without endometriosis, undergoing ovarian stimulation for intracytoplasmic sperm injection (ICSI). Therefore, a case-control study compared PTGS2 gene expression in the cumulus cells of 38 infertile patients with endometriosis and 40 without, using real-time polymerase chain reaction. For the first time, decreased expression of PTGS2 was found in cumulus cells of infertile women with endometriosis compared with controls (7.2 ± 10.5 versus 12.4 ± 15.7), which might be related to reduced levels of COX-2 in the cumulus cells of women with the disease. Consequently, we hypothesize that lower transcript levels of PTGS2 in cumulus cells may be involved in the impairment of oocyte quality, suggesting a possible mechanism involved in disease-related infertility. Copyright © 2017 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  9. Mouse cumulus-denuded oocytes restore developmental capacity completely when matured with optimal supplementation of cysteamine, cystine, and cumulus cells.

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    Zhou, Ping; Wu, Yan-Guang; Wei, De-Li; Li, Qing; Wang, Gang; Zhang, Jie; Luo, Ming-Jiu; Tan, Jing-He

    2010-04-01

    Our objectives were to study how cysteamine, cystine, and cumulus cells (CCs), as well as oocytes interact to increase oocyte intracellular glutathione (GSH) and thereby to establish an efficient in vitro maturation system for cumulus-denuded oocytes (DOs). Using M16 that contained no thiol as maturation medium, we showed that when supplemented alone, neither cystine nor cysteamine promoted GSH synthesis of mouse DOs, but they did when used together. Although goat CCs required either cysteamine or cystine to promote GSH synthesis, mouse CCs required both. In the presence of cystine, goat CCs produced cysteine but mouse CCs did not. Cysteamine reduced cystine to cysteine in cell-free M16. When TCM-199 that contained 83 microM cystine was used as maturation medium, supplementation with cysteamine alone had no effect, but supplementation with 100 microM cysteamine and 200 microM cystine increased blastulation of DOs matured with CC coculture to a level as high as achieved in cumulus-surrounded oocytes (COCs). Similar numbers of young were produced after two-cell embryos from mouse COCs or CC-cocultured DOs matured with optimal thiol supplementation were transferred to pseudopregnant recipients. It is concluded that 1) mouse CCs can use neither cysteamine nor cystine to promote GSH synthesis, but goat CCs can use either one; 2) goat CCs promote mouse oocyte GSH synthesis by reducing cystine to cysteine, but how they use cysteamine requires further investigation; and 3) mouse DOs can use neither cystine nor cysteamine for GSH synthesis, but they restore developmental capacity completely when matured in the presence of optimum supplementation of cysteamine, cystine, and CCs.

  10. Mitochondrial dysfunction and apoptosis in cumulus cells of type I diabetic mice.

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    Qiang Wang

    Full Text Available Impaired oocyte quality has been demonstrated in diabetic mice; however, the potential pathways by which maternal diabetes exerts its effects on the oocyte are poorly understood. Cumulus cells are in direct contact with the oocyte via gap junctions and provide essential nutrients to support oocyte development. In this study, we investigated the effects of maternal diabetes on the mitochondrial status in cumulus cells. We found an increased frequency of fragmented mitochondria, a decreased transmembrane potential and an aggregated distribution of mitochondria in cumulus cells from diabetic mice. Furthermore, while mitochondrial biogenesis in cumulus cells was induced by maternal diabetes, their metabolic function was disrupted as evidenced by lower ATP and citrate levels. Moreover, we present evidence suggesting that the mitochondrial impairments induced by maternal diabetes, at least in part, lead to cumulus cell apoptosis through the release of cytochrome c. Together the deleterious effects on cumulus cells may disrupt trophic and signaling interactions with the oocyte, contributing to oocyte incompetence and thus poor pregnancy outcomes in diabetic females.

  11. Proteomics-based systems biology modeling of bovine germinal vesicle stage oocyte and cumulus cell interaction.

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    Divyaswetha Peddinti

    Full Text Available BACKGROUND: Oocytes are the female gametes which establish the program of life after fertilization. Interactions between oocyte and the surrounding cumulus cells at germinal vesicle (GV stage are considered essential for proper maturation or 'programming' of oocytes, which is crucial for normal fertilization and embryonic development. However, despite its importance, little is known about the molecular events and pathways involved in this bidirectional communication. METHODOLOGY/PRINCIPAL FINDINGS: We used differential detergent fractionation multidimensional protein identification technology (DDF-Mud PIT on bovine GV oocyte and cumulus cells and identified 811 and 1247 proteins in GV oocyte and cumulus cells, respectively; 371 proteins were significantly differentially expressed between each cell type. Systems biology modeling, which included Gene Ontology (GO and canonical genetic pathway analysis, showed that cumulus cells have higher expression of proteins involved in cell communication, generation of precursor metabolites and energy, as well as transport than GV oocytes. Our data also suggests a hypothesis that oocytes may depend on the presence of cumulus cells to generate specific cellular signals to coordinate their growth and maturation. CONCLUSIONS/SIGNIFICANCE: Systems biology modeling of bovine oocytes and cumulus cells in the context of GO and protein interaction networks identified the signaling pathways associated with the proteins involved in cell-to-cell signaling biological process that may have implications in oocyte competence and maturation. This first comprehensive systems biology modeling of bovine oocytes and cumulus cell proteomes not only provides a foundation for signaling and cell physiology at the GV stage of oocyte development, but are also valuable for comparative studies of other stages of oocyte development at the molecular level.

  12. Effect of Acrylamide on Oocyte Nuclear Maturation and Cumulus Cells Apoptosis in Mouse In Vitro.

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    Shuzhen Liu

    Full Text Available Acrylamide (ACR is a chemical compound with severe neurotoxicity, genotoxicity, carcinogenicity and reproductive toxicity. Recent studies showed that ACR impairs the function of reproductive organs, e.g., epididymis and testes. In vitro maturation of mouse oocyte is a sensitive assay to identify potential chemical hazard to female fertility. The aim of this study was to evaluate the adverse effects of ACR on the nuclear maturation and cumulus cells apoptosis of mouse oocytes in vitro. Cumulus-oocyte complexes were incubated in a maturation medium containing 0, 5, 10 and 20 μM of ACR. Chromosome alignment and spindle morphology of oocytes was determined by immunofluorescence and confocal microscopy. Our results showed that oocytes exposed to different doses of ACR in vitro were associated with a significant decrease of oocyte maturation, significant increase of chromosome misalignment rate, occurrence of abnormal spindle configurations, and the inhibition of oocyte parthenogenetic activation. Furthermore, apoptosis of cumulus cells was determined by TUNEL and CASPASE-3 assay. Results showed that apoptosis in cumulus cells was enhanced and the expression of CASPASE-3 was increased after cumulus-oocyte complexes were exposed to ACR. Therefore, ACR may affect the nuclear maturation of oocytes via the apoptosis of cumulus cells in vitro.

  13. Embryo quality predictive models based on cumulus cells gene expression

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    Devjak R

    2016-06-01

    Full Text Available Since the introduction of in vitro fertilization (IVF in clinical practice of infertility treatment, the indicators for high quality embryos were investigated. Cumulus cells (CC have a specific gene expression profile according to the developmental potential of the oocyte they are surrounding, and therefore, specific gene expression could be used as a biomarker. The aim of our study was to combine more than one biomarker to observe improvement in prediction value of embryo development. In this study, 58 CC samples from 17 IVF patients were analyzed. This study was approved by the Republic of Slovenia National Medical Ethics Committee. Gene expression analysis [quantitative real time polymerase chain reaction (qPCR] for five genes, analyzed according to embryo quality level, was performed. Two prediction models were tested for embryo quality prediction: a binary logistic and a decision tree model. As the main outcome, gene expression levels for five genes were taken and the area under the curve (AUC for two prediction models were calculated. Among tested genes, AMHR2 and LIF showed significant expression difference between high quality and low quality embryos. These two genes were used for the construction of two prediction models: the binary logistic model yielded an AUC of 0.72 ± 0.08 and the decision tree model yielded an AUC of 0.73 ± 0.03. Two different prediction models yielded similar predictive power to differentiate high and low quality embryos. In terms of eventual clinical decision making, the decision tree model resulted in easy-to-interpret rules that are highly applicable in clinical practice.

  14. Interactions between oocytes and cumulus cells during in vitro maturation of porcine cumulus-oocyte complexes in a chemically defined medium: effect of denuded oocytes on cumulus expansion and oocyte maturation.

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    Appeltant, R; Somfai, T; Nakai, M; Bodó, S; Maes, D; Kikuchi, K; Van Soom, A

    2015-03-01

    The aim of the present study was to clarify interactions between oocytes and cumulus cells (CCs) on the level of cumulus expansion and oocyte maturation during IVM of cumulus-oocyte complexes (COCs) in a chemically defined medium using a system that allows individual tracking of oocytes. Especially, the influence of oocyte-secreted factors was investigated by the aid of addition of denuded oocytes (DOs) as a possible approach to improve the IVM system. The basic maturation medium was porcine oocyte medium with addition of gonadotropins only during the first 20 hours of IVM. During IVM, COCs were kept fixed to the bottom of culture dish by adhesive Cell-Tak coating, which enabled individual tracking of COCs during IVM. Size changes in COCs during IVM were measured by digital image analysis. Cumulus expansion in a porcine oocyte medium of intact COCs increased in a typical manner until 20 hours and decreased in size subsequently until 48 hours of IVM (P  0.05) but did enhance cumulus expansion of oocytectomized complexes (P medium: carbenoxolone repressed the expansion of COCs at 20 hours of IVM. In conclusion, the porcine oocyte enhances cumulus expansion both by gap junctional communications and presumably by oocyte-secreted factor production. Nevertheless, the presence of oocytes is not a prerequisite for this process. In return, CCs maintain meiotic arrest in cumulus-enclosed oocytes during the initial culture through gap junctions. On the basis of these findings, future research could investigate if coculture with DOs during IVM is beneficial for fertilization and embryo development. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Effect of Acrylamide on Oocyte Nuclear Maturation and Cumulus Cells Apoptosis in Mouse In Vitro

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    Liu, Shuzhen; Jiang, Ligang; Zhong, Tao; Kong, Shuhui; Zheng, Rongbin; Kong, Fengyun; Zhang, Cong; Zhang, Lei; An, Liguo

    2015-01-01

    Acrylamide (ACR) is a chemical compound with severe neurotoxicity, genotoxicity, carcinogenicity and reproductive toxicity. Recent studies showed that ACR impairs the function of reproductive organs, e.g., epididymis and testes. In vitro maturation of mouse oocyte is a sensitive assay to identify potential chemical hazard to female fertility. The aim of this study was to evaluate the adverse effects of ACR on the nuclear maturation and cumulus cells apoptosis of mouse oocytes in vitro. Cumulus–oocyte complexes were incubated in a maturation medium containing 0, 5, 10 and 20 μM of ACR. Chromosome alignment and spindle morphology of oocytes was determined by immunofluorescence and confocal microscopy. Our results showed that oocytes exposed to different doses of ACR in vitro were associated with a significant decrease of oocyte maturation, significant increase of chromosome misalignment rate, occurrence of abnormal spindle configurations, and the inhibition of oocyte parthenogenetic activation. Furthermore, apoptosis of cumulus cells was determined by TUNEL and CASPASE-3 assay. Results showed that apoptosis in cumulus cells was enhanced and the expression of CASPASE-3 was increased after cumulus–oocyte complexes were exposed to ACR. Therefore, ACR may affect the nuclear maturation of oocytes via the apoptosis of cumulus cells in vitro. PMID:26275143

  16. Effects of Mitochondrial Uncoupling Protein 2 Inhibition by Genipin in Human Cumulus Cells

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    Hongshan Ge

    2015-01-01

    Full Text Available UCP2 plays a physiological role by regulating mitochondrial biogenesis, maintaining energy balance, ROS elimination, and regulating cellular autophagy in numerous tissues. But the exact roles of UCP2 in cumulus cells are still not clear. Genipin, a special UCP2 inhibitor, was added into the cultural medium to explore the roles of UCP2 in human cumulus cells. There were no significant differences in ATP and mitochondrial membrane potential levels in cumulus cells from UCP2 inhibiting groups as compared with the control. The levels of ROS and Mn-SOD were markedly elevated after UCP2 inhibited Genipin. However, the ratio of reduced GSH to GSSG significantly declined after treatment with Genipin. UCP2 inhibition by Genipin also resulted in obvious increase in the active caspase-3, which accompanied the decline of caspase-3 mRNA. The level of progesterone in culture medium declined obviously after Genipin treatment. But there was no significant difference in estradiol concentrations. This study indicated that UCP2 is expressed in human cumulus cells and plays important roles on mediate ROS production, apoptotic process, and steroidogenesis, suggesting UCP2 may be involved in regulation of follicle development and oocyte maturation and quality.

  17. Estrogen Promotes the Development of Mouse Cumulus Cells in Coordination with Oocyte-Derived GDF9 and BMP15

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    Sugiura, Koji; Su, You-Qiang; Li, Qinglei; Wigglesworth, Karen; Matzuk, Martin M.; Eppig, John J.

    2010-01-01

    The differentiation and function of cumulus cells depend upon oocyte-derived paracrine factors, but studies on the estrogen receptor knockout mice suggested that estrogen also participates in these processes. This study investigates the possible coordination of estrogen and oocytes in the development and function of cumulus cells using cumulus expansion and the expression of transcripts required for expansion as functional endpoints. Preantral granulosa cell-oocyte complexes developed in vitro with 17β-estradiol (E2) exhibited increased levels of cumulus expansion and Has2 transcripts, encoding hyaluronan synthase 2, compared with those developed without E2. Moreover, cumulus cell-oocyte complexes (COCs) isolated from antral follicles and maintained in culture without E2 exhibited reduced cumulus expansion and Has2 mRNA levels compared with freshly isolated COCs. Exogenous E2, provided during the maintenance culture, alleviated these deficiencies. However, when oocytes were removed from COCs, E2 supplementation did not maintain competence to undergo expansion; the presence in culture of either fully grown oocytes or recombinant growth differentiation factor 9 (GDF9) was required. Recombinant bone morphogenetic protein 15, but not fibroblast growth factor 8, augmented the GDF9 effect. Oocytes or GDF9 suppressed cumulus cell levels of Nrip1 transcripts encoding nuclear receptor-interacting protein 1, a potential inhibitor of estrogen receptor signals. Therefore, E2 and oocyte-derived paracrine factors GDF9 and bone morphogenetic protein 15 coordinate to promote the development of cumulus cells and maintain their competence to undergo expansion. Furthermore, suppression of Nrip1 expression in cumulus cells by oocyte may be one mechanism mediating cross talk between oocyte and E2 signals that promotes follicular development. PMID:21047911

  18. Cumulus cell transcripts transit to the bovine oocyte in preparation for maturation

    DEFF Research Database (Denmark)

    Macaulay, Angus D.; Gilbert, Isabelle; Scantland, Sara

    2016-01-01

    , revealed transcripts common to all three fractions, suggesting the use of transferred transcripts for translation. Furthermore, the removal of potential RNA trafficking by stripping the cumulus cells caused a significant reduction in maturation rates, indicating the need for the cumulus cell RNA transfer...... that the somatic cells also contribute transcripts to the gamete. Here, we show that these transcripts can be visualized moving down the transzonal projections (TZPs) to the oocyte, and that a time course analysis revealed progressive RNA accumulation in the TZPs, indicating that RNA transfer occurs before......So far, the characteristics of a good quality egg have been elusive, similar to the nature of the physiological, cellular, and molecular cues leading to its production both in vivo and in vitro. Current understanding highlights a strong and complex interdependence between the follicular cells...

  19. Supplementation with cumulus cell masses improves the in vitro meiotic competence of porcine cumulus-oocytes complexes derived from small follicles.

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    Matsunaga, R; Funahashi, H

    2017-03-30

    The present study was conducted to examine the supplemented effect of cumulus cell masses (CCMs) derived from middle follicle (MF; 3-6 mm diameter) on the morphology and the meiotic or developmental competence of oocytes from small follicles (SF; 1-2 mm diameter). The number of cumulus cells surrounding oocytes just after collection was also lower in cumulus-oocyte complexes (COCs) from SF than MF. The ooplasmic diameter of oocytes was significantly smaller in SF-derived oocytes than MF-derived ones before and after in vitro maturation (IVM), whereas the diameter significantly increased during the culture. Co-culture of SF-derived COCs with MF-derived CCMs during IVM significantly improved the meiotic competence of the oocytes to the metaphase-II stage. Furthermore, the ooplasmic diameter of SF-derived COCs during IVM was increased to the similar size of MF-derived those in the presence of MF-derived CCMs. The abilities of oocytes to be penetrated, to form male pronuclear formation and to cleave or develop to the blastocyst stage were not affected by the co-culture with CCMs. Electrophoretic analysis of CCM secretions clearly showed the presence of more protein(s) approximately 27.6 kDa in the conditioned medium when supplemented with MF-derived CCMs. In conclusion, we demonstrate that supplementation with MF-derived CCMs improves the ooplasmic diameter and meiotic competence of SF-derived oocytes.

  20. Repeated superovulation may affect mitochondrial functions of cumulus cells in mice.

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    Xie, Juan-Ke; Wang, Qian; Zhang, Ting-Ting; Yin, Shen; Zhang, Cui-Lian; Ge, Zhao-Jia

    2016-10-04

    Controlled ovarian stimulation by exogenous gonadotrophins is a key procedure during the in vitro fertilization cycle to obtain a sufficient number of oocytes in humans. Previous studies demonstrated that repeated superovulation had deleterious effects on the ovaries. However, whether repeated superovulation adversely affects the mitochondrial functions of cumulus cells remains unclear. In this study, mice were divided into three groups: superovulation once (R1); superovulation three times (R3), and superovulation five times (R5). We evaluated the effects of repeated superovulation on mitochondrial DNA copies (mtDNA) and observed decreased mtDNA copies per cell with increasing number of superovulation cycles. Further, we investigated the DNA methylation status in exon 2 and the mRNA expression level of nuclear-encoded DNA polymerase gamma A (PolgA). The results showed that the DNA methylation levels of PolgA in R1 and R5 were slightly lower than in R3. Additionally, the altered DNA methylation in PolgA coincided with the changes in PolgA expression in cumulus cells. We also found that the mRNA expression of COX1, CYTB, ND2, and ND4 was altered by repeated superovulation in cumulus cells. Thus, repeated superovulation had adverse effects on mitochondrial function.

  1. Dynamic changes of connexin-43, gap junctional protein, in outer layers of cumulus cells are regulated by PKC and PI 3-kinase during meiotic resumption in porcine oocytes.

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    Shimada, M; Maeda, T; Terada, T

    2001-04-01

    Mammalian oocytes are surrounded by numerous layers of cumulus cells, and the loss of gap junctional communication in the outer layers of cumulus cells induces meiotic resumption in oocytes. In this study, we investigated the dynamic changes in the gap junctional protein connexin-43 in cumulus cells during the meiotic resumption of porcine oocytes. The amount of connexin-43 in all layers of cumulus cells recovered from cumulus-oocyte complexes was increased after 4-h cultivation. However, at 12-h cultivation, the positive signal for connexin-43 immunoreactivity was markedly reduced in the outer layers of cumulus cells. When these reductions of connexin-43 were blocked by protein kinase C (PKC) or phosphatidylinositol (PI) 3-kinase inhibitor, networks of filamentous bivalents (i.e., advanced chromosomal status) were undetectable in the germinal vesicle of the oocyte. After 28-h cultivation, when the majority of oocytes were reaching the metaphase I (MI) stage, the connexin-43 in the inner layers of cumulus cells was phosphorylated, regardless of mitogen-activated protein (MAP) kinase activation. These results suggest that the initiation of meiotic resumption, namely, the formation of networks of filamentous bivalents in germinal vesicle, is associated with the reduction of gap junctional protein connexin-43 in the outer layers of cumulus cells via the PKC and/or PI 3-kinase pathway. Moreover, the connexin-43 in the inner layers of cumulus cells is phosphorylated during meiotic progression beyond the MI stage, regardless of MAP kinase activation in cumulus cells surrounding the oocyte.

  2. The effects of roscovitine on cumulus cell apoptosis and the developmental competence of domestic cat oocytes.

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    Sananmuang, T; Techakumphu, M; Tharasanit, T

    2010-01-15

    The developmental competence of cat oocytes matured in vitro is relatively poor when compared with that of in vivo oocytes. The study aimed to investigate the effect of roscovitine on the developmental competence of cat Felis catus oocytes matured in vitro. Cumulus-oocyte complexes (COCs) were classified as Grade I and II to III. Groups of COCs were cultured in 0, 12.5, 25, 50, 100, and 200 microM roscovitine for 24h and were either fixed to assess the stages of nuclear maturation (Experiment 1) or additionally matured in vitro for 24h before fixation (Experiment 2). In Experiment 3, cumulus cells from the COCs treated with roscovitine were examined for apoptosis. Experiment 4 examined the developmental competence of cat oocytes after roscovitine treatment and in vitro fertilization in terms of cleavage and morula and blastocyst formation rates. Roscovitine reversibly arrested cat oocytes at an immature stage in a dose-dependent manner. Roscovitine at 12.5 and 25 microM demonstrated less efficiency compared with that of other doses. However, higher doses of roscovitine induced cumulus cell apoptosis and resulted in a high number of degenerated oocytes after in vitro maturation. Roscovitine at 12.5 and 25 microM were therefore used to evaluate their effect on embryo development. Pretreatment with 12.5 and 25 microM roscovitine prior to in vitro maturation decreased the developmental competence of cat oocytes compared with that of non-roscovitine-treated controls. In conclusion, roscovitine reversibly maintained cat oocytes at the germinal vesicle stage without detrimental effect on nuclear maturation. However, it negatively affected cumulus cell viability and developmental competence.

  3. Cumulus cells steroidogenesis is influenced by the degree of oocyte maturation

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    Barboni Barbara

    2003-05-01

    Full Text Available Abstract Background The possibility to predict the ability of a germ cell to properly sustain embryo development in vitro or in vivo as early as possible is undoubtedly the main problem of reproductive technologies. To date, only the achievement of nuclear maturation and cumulus expansion is feasible, as all the studies on cytoplasmic maturation are too invasive and have been complicated by the death of the cells analyzed. The authors studied the possibility to test the cytoplasmic quality of pig oocytes by evaluating their ability to produce steroidogenesis enabling factor(s. To this aim, oocytes matured under different culture conditions that allowed to obtain gradable level of cytoplasmic maturation, were used to produce conditioned media (OCM. The secretion of the factor(s in conditioned media was then recorded by evaluating the ability of the spent media to direct granulosa cells (GC steroidogenesis. Methods In order to obtain germ cells characterized by a different degree of developmental competence, selected pig oocytes from prepubertal gilts ovaries were cultured under different IVM protocols; part of the matured oocytes were used to produce OCM, while those remaining were submitted to in vitro fertilization trials to confirm their ability to sustain male pronuclear decondensation. The OCM collected were finally used on cumulus cells grown as monolayers for 5 days. The demonstration that oocytes secreted factor(s can influence GC steroidogenesis in the pig was confirmed in our lab by studying E2 and P4 production by cumulus cells monolayers using a radioimmunoassay technique. Results Monolayers obtained by growing GC surrounding the oocytes for five days represent a tool, which is practical, stable and available in most laboratories; by using this bioassay, we detected the antiluteal effect of immature oocytes, and for the first time, demonstrated that properly matured germ cells are able to direct cumulus cells steroidogenesis by

  4. Cumulus Cell Role on Mouse Germinal Vesicle Oocyte Maturation, Fertilization, and Subsequent Embryo Development to Blastocyst Stage In Vitro

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    Reza Mahmodi

    2009-01-01

    Full Text Available Objective: The purpose of this study is to investigate the effect of cumulus cells on maturation,fertilization and subsequent development of mouse germinal vesicle oocytes.Materials and Methods: A total of 470 germinal vesicle (GV oocytes were obtained from26 ovaries of 3- 4 week old ICR female mice 48 hours after injection of 5 IU pregnant mareserum gonadotropin (PMSG. Collected oocytes were divided into two groups; group I: GVoocytes without cumulus cells (denuded oocyte, group II: GV oocytes with cumulus cells(cumulus-oocyte complex. The oocytes in both groups were cultured in TCM-199 mediumsupplemented with 10% fetal bovine serum (FBS for 22- 24 hours in a humidified atmosphereof 5% CO2 in air at 37°C. Oocyte maturation was scored under inverted microscope.To do in vitro fertilization, matured oocytes from each group were placed in T6 mediumand capacitated spermatozoa were added. Then the fertilized oocytes were cultured andassessed for cleavage to the 2-cell stage 24 hours and production of blastocyst 120 hoursafter fertilization. Data was analyzed by chi-square test and differences in the values wereconsiderable significant when p<0.05.Results: Maturation, fertilization, cleavage and blastocyst rates in denuded oocytes were:76.32%, 57.49%, 51.15% and 19.14% respectively. In the cumulus-oocyte complex rateswere: 89.41%, 80.76%, 75.58% and 45.62% respectively; all in the cumulus-oocyte complexwere significantly higher than those of denuded oocytes (p<0.05.Conclusion: The present study indicates that cumulus cells have important role duringmaturation, fertilization and subsequent embryo development to the blastocyst stage.

  5. Specific genes are selectively expressed between cumulus and granulosa cells from individual human pre-ovulatory follicles

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    Grøndahl, M L; Andersen, C Yding; Bogstad, J;

    2012-01-01

    During folliculogenesis the granulosa cells differentiate into two cell types: Cumulus cells (CC) and mural granulosa cells (MGC). The objective of the study was to generate and compare the transcriptomes of MGC and CC from the pre-ovulatory follicle to characterize the detailed profile of the two...

  6. Detection of RUNX2 gene expression in cumulus cells in women undergoing controlled ovarian stimulation

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    Papamentzelopoulou Myrto

    2012-11-01

    Full Text Available Abstract Background RUNX2 is a transcription factor, whose expression has been recently identified in the mouse ovary. Regulation of RUNX2 expression and its function in the human ovary have not been determined yet. The aim of the present study is the investigation of the possible correlation between RUNX2 gene expression in cumulus cells and controlled ovarian stimulation and pregnancy outcomes after ART treatment. Methods A total of 41 patients undergoing ICSI treatment for male factor infertility were enrolled into a specific ART program, during which cumulus cells were collected. The expression of RUNX2 gene in cumulus cells was examined by real-time PCR. Results Concerning RUNX2 gene expression, 12 out of 41 women were detected with RUNX2 expression, with ratios ranging from 0.84 to 1.00, while 28 out of 41 women had no expression (ratio = 0. Only 1 woman presented a weak RUNX2 gene expression (ratio = 0.52. From 8 women that proceeded to pregnancy, 7 of them did not express RUNX2 gene in cumulus cells, while one was the woman with weak gene expression that also achieved pregnancy. The group of women without RUNX2 expression presented higher number of follicles (p = 0.013, higher number of retrieved oocytes (p = 0.016, higher basal LH serum levels (p = 0.016 and higher peak estradiol levels (p = 0.013, while the number of fertilized oocytes differed marginally between the two groups (p = 0.089. Moreover, RUNX2 expression was negatively associated with LH levels (OR = 0.22, p = 0.021 and E2 levels (OR = 0.25, p = 0.026. Conclusions Consequently, based on the preliminary findings of the present pilot study a potential inhibitory mechanism of RUNX2 gene is observed in the ovary when high mRNA levels are detected, suggesting that RUNX2 could possibly be used as a candidate genetic marker in the monitoring of the outcome of an ART treatment.

  7. The apoptotic profile of human cumulus cells changes with patient age and after exposure to sperm but not in relation to oocyte maturity.

    Science.gov (United States)

    Moffatt, Odette; Drury, Sarah; Tomlinson, Matthew; Afnan, Masoud; Sakkas, Denny

    2002-05-01

    To determine the expression of apoptosis-associated molecules on cumulus cells removed from individual oocytes of different maturity, inseminated oocytes and to investigate the possibility of an age-dependent expression. Analysis of apoptosis in cumulus cells isolated from oocytes of different stages of maturity. Assisted reproductive technology program of the Birmingham Women's Hospital, Birmingham, UK. Patients undergoing intracytoplasmic sperm injection or IVF cycles. Percentage of positive cumulus cells when assessed for nuclear DNA damage using the terminal deoxyuridine nucleotide end-labeling assay or stained with antibodies [Fas, Fas ligand, the antiapoptotic protein Bcl-xl, and the RNA-binding protein (TIAR)]. Cumulus cells collected from mature oocytes showed no significant difference in the percentage of apoptotic markers compared to those recovered from immature oocytes, whereas those from patients >/=38 years differed significantly. When cumulus cells were exposed to sperm the levels of apoptotic markers altered significantly from those not exposed to sperm. The results show that the cumulus cells of human oocytes are equipped with a mechanism to undergo apoptosis and that patient age and the exposure of cumulus cells to sperm can alter their profiles of apoptotic markers.

  8. Identification of Polycystic Ovary Syndrome (PCOS) Specific Genes in Cumulus and Mural Granulosa Cells

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    Aydos, Alp; Gurel, Aykut; Oztemur Islakoglu, Yasemin; Noyan, Senem; Gokce, Bagdagul; Ecemis, Tolga; Kaya, Cemil; Aksu, Arif Tarik

    2016-01-01

    Polycystic ovary syndrome (PCOS) is a metabolic and endocrine disorder which affects women of reproductive age with prevalence of 8–18%. The oocyte within the follicle is surrounded by cumulus cells (CCs), which connect with mural granulosa cells (MGCs) that are responsible for secreting steroid hormones. The main aim of this study is comparing gene expression profiles of MGCs and CCs in PCOS and control samples to identify PCOS-specific differentially expressed genes (DEGs). In this study, two microarray databases were searched for mRNA expression microarray studies performed with CCs and MGCs obtained from PCOS patients and control samples. Three independent studies were selected to be integrated with naive meta-analysis since raw meta-data from these studies were found to be highly correlated. DEGs in these somatic cells were identified for PCOS and control groups. This study enabled us to reveal dysregulation in MAPK (mitogen activated protein kinase), insulin and Wnt signaling pathways between CCs and MGCs in PCOS. The meta-analysis results together with qRT-PCR validations provide evidence that molecular signaling is dysregulated through MGCs and CCs in PCOS, which is important for follicle and oocyte maturation and may contribute to the pathogenesis of the syndrome. PMID:27997581

  9. Hyaluronidase alters the lipid profile of cumulus cells as detected by MALDI-TOF MS and multivariate analysis.

    Science.gov (United States)

    Montani, Daniela Antunes; Regiani, Thaís; Victorino, Amanda Begati; Camillo, Jacqueline; Pilau, Eduardo Jorge; Gozzo, Fábio Cesar; Zylbersztejn, Daniel Suslik; Ferreira, Christina Ramires; Lo Turco, Edson Guimarães

    2014-09-01

    This research aimed to study the changes in lipid composition in cumulus cells using hyaluronidase according to the intracytoplasmic sperm injection protocol commonly used in human reproduction clinics. The lipid extraction was performed by the Blight-Dyer protocol and the lipid profiles were obtained by MALDI-TOF MS in positive and negative modes. The mass spectra data were processed with MassLynx and the statistical analysis was performed using MetaboAnalyst 2.0. Fifteen ions were selected for each mode as potential markers for differences between the groups. These ions were identified in the human metabolome database as phosphatidylserine with and without treatment, phosphatidylethanolamine in the after treatment group and phosphatidylinositol in the before treatment group, which are lipids that may be involved in cell apoptosis and signaling. We concluded that MALDI-TOF MS coupled with multivariate analysis can be utilized as a strategy to obtain and study the lipid profiles of cumulus cells and as a tool to study the metabolic state of cumulus cells.

  10. Effect of Mitochondrial Transplantation from Cumulus Granular Cells to the Early Embryos of Aged Mice

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Objective To assess the role of mitochondria in the early embryonic development of ageing mice.Methods Mitochondria isolated from cumulus granular cells of aged mice were microinjected into oocytes or zygotes of aged mice. In the setting of oocyte injection, mitochondria were transferred via intracytoplasmic sperm injection (ICSI+MIT), and ICSI without mitochondrial transfer. In the setting of zygote injection, mitochondria were directly microinjected into fertilized oocytes (MIT), and those injected with buffer alone (mock injection) or not injected (uninjected) served as controls.Results Although the rates of oocyte cleavage between ICSI and ICSI+MIT groups were not statistically different (P>0.05), the rate of blastocyst in the ICSI+MIT group was significantly higher than that in ICSI group (P<0.05). Although both the cleavage and blastocyst rates of mock injection group were significantly lower than those of uninjected group (P<0.05), likely due to mechanical damages of the cells by microinjection, the decrease of these rates was prevented by mitochondrial transfer. After mitochondrial transfer, the rates of both cleavage and blastocyst were significantly improved over the mock-injection group (P<0.05).Conclusion Mitochondrial transplantation can improve the developmental potential of early embryos of aged mice.

  11. Nitric oxide acts through different signaling pathways in maturation of cumulus cell-enclosed mouse oocytes

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    M Abbasi

    2009-03-01

    Full Text Available ABSTRACT Background: Nitric oxide (NO have a dual action in mouse oocyte meiotic maturation which depends on its concentration, but the mechanisms by which it influences oocyte maturation has not been exactly clarified. In this study different signaling mechanisms which exist for in vitro maturation of meiosis was examined in cumulus cell-enclosed oocytes (CEOs after injection of pregnant mare's serum gonadotropin (PMSG to immature female mice. Methods: The CEOs were cultured in spontaneous maturation and hypoxanthine (HX arrested model. Results: Sodium nitroprusside (SNP, an NO donor, 10mM delayed germinal vesicle breakdown (GVBD significantly during the first 5 hrs of incubation and inhibited the formation of first polar body (PB1 at the end of 24 hrs of incubation. SNP (10-5M stimulated the meiotic maturation of oocytes significantly by overcoming the inhibition of HX. Sildenafil (a cGMP stimulator, 100 nM, had a significant inhibitory effects on both spontaneous meiotic maturation and HX-arrested meiotic maturation. Forskolin (an adenylate cyclase stimulator, 6µM and SNP (10mM had the same effects on GVBD. Forskolin reversed the SNP (10-5M stimulated meiotic maturation. Conclusion: These results suggest that differences in pathways are present between SNP-inhibited spontaneous meiotic maturation and SNP-stimulated meiotic maturation in mouse oocytes

  12. The effect of cumulus cells on domestic cat (Felis catus) oocytes during in vitro maturation and fertilization.

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    Sowińska, N; Frankowska, K; Filipczyk, A; Adamaszek, A; Nalik, K; Fic, K; Pietsch-Fulbiszewska, A

    2017-04-01

    The aim of this study was to evaluate the effect of co-culture of denuded oocytes with cumulus cells (CC) or cumulus-oocyte complexes (COCs) on in vitro maturation (IVM) and in vitro fertilization (IVF). Immature oocytes were collected from ovaries of domestic cats following a routine ovariectomy. Oocytes were matured in vitro for 24 hr within four groups: (i) denuded oocytes (DO), (ii) DO co-cultured with CC, (iii) DO co-cultured with COC and (iv) COC as a control group. In further experiments, COCs were matured in vitro for 24 hr, and then, oocytes were randomly divided into four groups as previously described and fertilized in vitro. Embryos were cultured for up to 7 days. At the end of each experiment, oocytes/embryos were stained with Hoechst 33342 solution and observed under an inverted fluorescence microscope. The results of oocyte maturation showed that their meiotic competence decreased significantly in all experimental groups, compared to the control group. The maturation rates were approximately 45%, 24%, 43% and 76% in experiment 1, and 21%, 14%, 33% and 50% in experiment 2 in groups (i), (ii), (iii) and (iv), respectively. Examination of in vitro fertilization revealed that embryos developed up to the morula stage in all experimental groups. DO and oocytes cultured with COC during fertilization showed a lower cleavage rate-36% and 25% as opposed to those co-cultured with loose CC and the control group-43% and 42%, respectively. Results of this study indicate that cumulus cells connected with an oocyte into a cumulus-oocyte complex are irreplaceable for the maturation of domestic cat oocyte, but that the addition of loose CC may be beneficial for IVF. © 2016 Blackwell Verlag GmbH.

  13. Decreased expression of tumor necrosis factor-alpha-stimulated gene 6 in cumulus cells of the cyclooxygenase-2 and EP2 null mice.

    Science.gov (United States)

    Ochsner, Scott A; Russell, Darryl L; Day, Anthony J; Breyer, Richard M; Richards, Joanne S

    2003-03-01

    Ovulation, the release of fertilizable oocytes from mature follicles, involves tissue remodeling and increased prostaglandin (PG) signaling. Cyclooxygenase (COX)-2 is the rate-limiting enzyme during PG synthesis. Female mice null for either COX-2 or the PGE(2) receptor EP2 are infertile, show decreased ovulation, and exhibit abnormal cumulus expansion. Cumulus expansion is the production of a complex extracellular matrix surrounding the cumulus-oocyte complex (COC). Matrix components consist of hyaluronan, proteoglycans, and proteins with hyaluronan binding domains. One such hyaluronan binding protein is TNFalpha-stimulated gene 6 (TSG-6). By various methods, we show induction of TSG-6 and hyaluronan synthase-2 mRNA in ovaries of mice treated with pregnant mare serum gonadotropin and human chorionic gonadotropin. By in situ hybridization, we show that both genes are expressed in periantral mural granulosa cells and cumulus cells of the mouse ovary. Notably, RT-PCR and in situ hybridization show that TSG-6 mRNA but not hyaluronan synthase-2 mRNA expression is selectively reduced in cumulus cells of COX-2 and EP2 null mice. Western analysis further confirms that TSG-6 protein is reduced in isolated COCs but remains covalently associated with inter alpha-trypsin inhibitor in COX-2 null mice. These observations identify TSG-6 as a target of PG action and show that its production in ovulatory follicles is associated with proper formation of the cumulus-derived extracellular matrix.

  14. Bovine cumulus-oocyte disconnection in vitro

    DEFF Research Database (Denmark)

    Maddox-Hyttel, Poul

    1987-01-01

    Cumulus-oocyte complexes were obtained from cows by aspiration of small (1-6 mm in diameter) antral follicles after slaughter. Complexes with a compact multilayered cumulus investment were cultured and processed for transmission electron microscopy after different periods of culture including a 0...

  15. Expression profiling of cumulus cells reveals functional changes during ovulation and central roles of prostaglandin EP2 receptor in cAMP signaling.

    Science.gov (United States)

    Tamba, Shigero; Yodoi, Rieko; Morimoto, Kazushi; Inazumi, Tomoaki; Sukeno, Mamiko; Segi-Nishida, Eri; Okuno, Yasushi; Tsujimoto, Gozoh; Narumiya, Shuh; Sugimoto, Yukihiko

    2010-06-01

    To understand the role of prostaglandin (PG) receptor EP2 (Ptger2) signaling in ovulation and fertilization, we investigated time-dependent expression profiles in wild-type (WT) and Ptger2(-/-) cumuli before and after ovulation by using microarrays. We prepared cumulus cells from mice just before and 3, 9 and 14 h after human chorionic gonadotropin injection. Key genes including cAMP-related and epidermal growth factor (EGF) genes, as well as extracellular matrix- (ECM-) related and chemokine genes were up-regulated in WT cumuli at 3 h and 14 h, respectively. Ptger2 deficiency differently affected the expression of many of the key genes at 3 h and 14 h. These results indicate that the gene expression profile of cumulus cells greatly differs before and after ovulation, and in each situation, PGE(2)-EP2 signaling plays a critical role in cAMP-regulated gene expression in the cumulus cells under physiological conditions.

  16. Transcriptome dynamics and molecular cross-talk between bovine oocyte and its companion cumulus cells

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    Looft C

    2011-01-01

    Full Text Available Abstract Background The bi-directional communication between the oocyte and its companion cumulus cells (CCs is crucial for development and functions of both cell types. Transcripts that are exclusively expressed either in oocytes or CCs and molecular mechanisms affected due to removal of the communication axis between the two cell types is not investigated at a larger scale. The main objectives of this study were: 1. To identify transcripts exclusively expressed either in oocyte or CCs and 2. To identify those which are differentially expressed when the oocyte is cultured with or without its companion CCs and vice versa. Results We analyzed transcriptome profile of different oocyte and CC samples using Affymetrix GeneChip Bovine Genome array containing 23000 transcripts. Out of 13162 genes detected in germinal vesicle (GV oocytes and their companion CCs, 1516 and 2727 are exclusively expressed in oocytes and CCs, respectively, while 8919 are expressed in both. Similarly, of 13602 genes detected in metaphase II (MII oocytes and CCs, 1423 and 3100 are exclusively expressed in oocytes and CCs, respectively, while 9079 are expressed in both. A total of 265 transcripts are differentially expressed between oocytes cultured with (OO + CCs and without (OO - CCs CCs, of which 217 and 48 are over expressed in the former and the later groups, respectively. Similarly, 566 transcripts are differentially expressed when CCs mature with (CCs + OO or without (CCs - OO their enclosed oocytes. Of these, 320 and 246 are over expressed in CCs + OO and CCs - OO, respectively. While oocyte specific transcripts include those involved in transcription (IRF6, POU5F1, MYF5, MED18, translation (EIF2AK1, EIF4ENIF1 and CCs specific ones include those involved in carbohydrate metabolism (HYAL1, PFKL, PYGL, MPI, protein metabolic processes (IHH, APOA1, PLOD1, steroid biosynthetic process (APOA1, CYP11A1, HSD3B1, HSD3B7. Similarly, while transcripts over expressed in OO + CCs

  17. Characterization of the effects of metformin on porcine oocyte meiosis and on AMP-activated protein kinase activation in oocytes and cumulus cells.

    Science.gov (United States)

    Bilodeau-Goeseels, Sylvie; Magyara, Nora; Collignon, Coralie

    2014-05-01

    The adenosine monophosphate-activated protein kinase (AMPK) activators 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR) and metformin (MET) inhibit resumption of meiosis in porcine cumulus-enclosed oocytes. The objective of this study was to characterize the inhibitory effect of MET on porcine oocyte meiosis by: (1) determining the effects of an AMPK inhibitor and of inhibitors of signalling pathways involved in MET-induced AMPK activation in other cell types on MET-mediated meiotic arrest in porcine cumulus-enclosed oocytes; (2) determining whether MET and AICAR treatments lead to increased activation of porcine oocyte and/or cumulus cell AMPK as measured by phosphorylation of its substrate acetyl-CoA carboxylase; and (3) determining the effects of inhibition of the AMPK kinase, Ca2+/calmodulin-dependent protein kinase kinase (CaMKK), and Ca2+ chelation on oocyte meiotic maturation and AMPK activation in porcine oocytes and cumulus cells. The AMPK inhibitor compound C (CC; 1 μM) did not reverse the inhibitory effect of AICAR (1 mM) and MET (2 mM) on porcine oocyte meiosis. Additionally, CC had a significant inhibitory effect on its own. eNOS, c-Src and PI-3 kinase pathway inhibitors did not reverse the effect of metformin on porcine oocyte meiosis. The level of acetyl-CoA carboxylase (ACC) phosphorylation in oocytes and cumulus cells did not change in response to culture in the presence of MET, AICAR, CC, the CaMKK inhibitor STO-609 or the Ca2+ chelator BAPTA-AM for 3 h, but STO-609 increased the percentage of porcine cumulus-enclosed oocytes (CEO) that remained at the germinal vesicle (GV) stage after 24 h of culture. These results indicate that the inhibitory effect of MET and AICAR on porcine oocyte meiosis was probably not mediated through activation of AMPK.

  18. Research Resources: Comparative MicroRNA Profiles in Human Corona Radiata Cells and Cumulus Oophorus Cells Detected by Next-Generation Small RNA Sequencing

    Science.gov (United States)

    Zhang, Yuan-Wei; Liu, Yu-Sheng; Ma, Chun-Hong

    2014-01-01

    During folliculogenesis, cumulus cells surrounding the oocyte differentiate into corona radiata cells (CRCs) and cumulus oophorus cells (COCs), which are involved in gonadal steroidogenesis and the development of germ cells. Several studies suggested that microRNAs (miRNAs) play an important regulatory role at the post-transcriptional level in cumulus cells. However, comparative miRNA profiles and associated processes in human CRCs and COCs have not been reported before. In this study, miRNA profiles were obtained from CRCs and COCs using next generation sequencing in women undergoing controlled ovarian stimulation for IVF. A total of 785 and 799 annotated miRNAs were identified in CRCs and COCs, while high expression levels of six novel miRNAs were detected both in CRCs and in COCs. In addition, different expression patterns in CRCs and COCs were detected in 72 annotated miRNAs. To confirm the miRNA profile in COCs and CRCs, quantitative real-time PCR was used to validate the expression of annotated miRNAs, differentially expressed miRNAs, and novel miRNAs. The miRNAs in the let-7 family were found to be involved in the regulation of a broad range of biological processes in both cumulus cell populations, which was accompanied by a large amount of miRNA editing. Bioinformatics analysis showed that amino acid and energy metabolism were targeted significantly by miRNAs that were differentially expressed between CRCs and COCs. Our work extends the current knowledge of the regulatory role of miRNAs and their targeted pathways in folliculogenesis, and provides novel candidates for molecular biomarkers in the research of female infertility. PMID:25188034

  19. Research resources: comparative microRNA profiles in human corona radiata cells and cumulus oophorus cells detected by next-generation small RNA sequencing.

    Directory of Open Access Journals (Sweden)

    Xian-Hong Tong

    Full Text Available During folliculogenesis, cumulus cells surrounding the oocyte differentiate into corona radiata cells (CRCs and cumulus oophorus cells (COCs, which are involved in gonadal steroidogenesis and the development of germ cells. Several studies suggested that microRNAs (miRNAs play an important regulatory role at the post-transcriptional level in cumulus cells. However, comparative miRNA profiles and associated processes in human CRCs and COCs have not been reported before. In this study, miRNA profiles were obtained from CRCs and COCs using next generation sequencing in women undergoing controlled ovarian stimulation for IVF. A total of 785 and 799 annotated miRNAs were identified in CRCs and COCs, while high expression levels of six novel miRNAs were detected both in CRCs and in COCs. In addition, different expression patterns in CRCs and COCs were detected in 72 annotated miRNAs. To confirm the miRNA profile in COCs and CRCs, quantitative real-time PCR was used to validate the expression of annotated miRNAs, differentially expressed miRNAs, and novel miRNAs. The miRNAs in the let-7 family were found to be involved in the regulation of a broad range of biological processes in both cumulus cell populations, which was accompanied by a large amount of miRNA editing. Bioinformatics analysis showed that amino acid and energy metabolism were targeted significantly by miRNAs that were differentially expressed between CRCs and COCs. Our work extends the current knowledge of the regulatory role of miRNAs and their targeted pathways in folliculogenesis, and provides novel candidates for molecular biomarkers in the research of female infertility.

  20. Recombinant fetuin-B protein maintains high fertilization rate in cumulus cell-free mouse oocytes.

    Science.gov (United States)

    Dietzel, E; Floehr, J; Van de Leur, E; Weiskirchen, R; Jahnen-Dechent, W

    2017-01-01

    Does fetuin-B inhibit premature zona pellucida (ZP) hardening in mouse oocytes in vitro and thus increase IVF rate? Supplementation of oocyte in vitro maturation (IVM) media with recombinant mouse fetuin-B (rmFetuB) increased fertilization rate without affecting mouse embryo development into blastocysts. Mice deficient in fetuin-B are infertile owing to premature ZP hardening. Premature ZP hardening also occurs during oocyte IVM leading to decreased fertilization rate. We fertilized batches of 20-30 mouse metaphase II (Mll) stage oocytes from C57BL/6 mice with fresh sperm, and studied early embryo development until blastocyst hatching. Oocytes were maintained with or without rmFetuB during IVM and IVF. Exogenous rmFetuB was added to media prior to oocyte isolation. ZP hardening was quantified by chymotrypsin digestion timing and by counting attached sperm. In the absence of cumulus cells, rmFetuB dose-dependently inhibited ZP hardening and increased IVF rate (P = 0.039). Fetuin-B at ≥0.03 mg/ml also inhibited physiological, fertilization-triggered ZP hardening (indicated by increased sperm binding, P = 0.0002), without increasing embryo death. Exogenous rmFetuB increased IVF rate for up to 5 hours of IVM (P = 0.02 at 1 hour, P = 0.01 at 5 hours of IVM). Mll stage oocytes in this study were isolated from the ampullae of fetuin-B expressing mice. Thus, oocytes were protected against premature ZP hardening by endogenous fetuin-B. In humans and livestock, oocytes are usually isolated by follicle puncture before ovulation. In this situation, the deprivation of endogenous fetuin-B would occur earlier and the effect of exogenous fetuin-B in the IVF medium may be even more pronounced. Fertilization-triggered ZP hardening is essential for embryo development but in this study the effect of fetuin-B supplementation was only studied to blastocyst stage. Any influence of added fetuin-B on later embryo development after transplantation remains to be determined. The astacin

  1. Low chronic ethanol consumption affects ovulation and PGE synthesis by the cumulus cell masses in mice.

    Science.gov (United States)

    Cebral, E; Motta, A; de Gimeno, M F

    1999-02-01

    Central and gonadal function can be affected by chronic consumption of high and moderate doses of ethanol. Few studies have been conducted to determine the effect of ethanol intake at ovarian and gamete level. Previously, we showed that fertilization rates of low chronic ethanol treated female mice were diminished. Also, our recent results indicated that moderate chronic intake of ethanol by immature females could alter the ovulatory quantity and produce morphological alterations in the superovulated oocytes. Furthermore, PGE production by oocyte cumulus complexes (OCCs) was reduced in the females treated with 10% (w/v) ethanol. In the present investigation, we studied the effects of 5% ethanol treatment given to immature mice for 30 days on the quality and quantity of oocytes superovulated at 16 h posthuman chronic gonadotrophin. Treated females had impaired ovulation rates (P < 0.05) as compared to the controls. The percentage of activated and morphologically abnormal oocytes was elevated in the ethanol-treated females (P < 0.05). PGE synthesis by the OCCs was higher than in the controls (P < 0.01). In summary, the administration of long-term ethanol at a relatively low dose to immature females produces decreased ovulation rates, abnormal oocyte morphology with high spontaneous activation and altered levels of PGE production by the oocytes' cumulus complexes. The relationship between the oocyte quality and abnormal synthesis of PGE is discussed.

  2. In vitro production of bovine embryos: cumulus/granulosa cell gene expression patterns point to early atresia as beneficial for oocyte competence

    DEFF Research Database (Denmark)

    Mazzoni, Gianluca; Razza, Eduardo; Pedersen, Hanne S.

    2017-01-01

    In vitro production (IW) of bovine embryos has become widespread technology implemented in cattle breeding and production. Here, we review novel data on cumulus/granulosa cell gene expression, as determined by RNAseq on cellular material from pooled follicular fluids at the single animal level...

  3. Theca cells and theca-cell conditioned medium inhibit the progression of FSH-induced meiosis of bovine oocytes surrounded by cumulus cells connected to membrana granulosa.

    Science.gov (United States)

    van Tol, H T; Bevers, M M

    1998-11-01

    The effect of follicular cells and their conditioned media on the FSH-induced oocyte maturation of oocytes surrounded by cumulus cells connected to the membrana granulosa (COCGs) was investigated. COCGs and cumulus oocyte complexes (COCs) were cultured for 22 hr in M199 supplemented with 0.05 IU FSH/ml in either the presence of pieces of theca cell layer or in the presence of pieces of membrana granulosa. COCGs and COCs were also cultured for 22 hr in either theca-cell conditioned medium (CMt) or in granulosa cell conditioned medium (CMg), both supplemented with 0.05 IU FSH/ml. To investigate the importance of cell-cell contacts between granulosa cells and cumulus cells, oocytes were cultured as COCs in CMt, as COCs in CMt supplemented with pieces of membrana granulosa, or as COCGs in CMt. In all groups the medium was supplemented with 0.05 IU FSH/ml. After culture the nuclear status of the oocytes was assessed using orcein staining. Culture of COCGs in the presence of theca cells as well as in CMt resulted in a significantly decreased proportion of oocytes that had undergone germinal vesicle breakdown (GVBD) at the end of the culture period as compared to the control. Of the oocytes that resumed meiosis in the presence of theca cells or in CMt, the proportion of oocytes that progressed up to the MII stage was significantly reduced. This indicates the production of a meiosis-inhibiting factor by theca cells. Culture with COCs instead of COCGs resulted in comparable results although the effect was less pronounced. The significant effect on the progression of meiosis of oocytes cultured as COCGs or as COCs, obtained in the presence of granulosa cells or in CMg, was much weaker than the effect of theca cells or culture in CMt. Culture of COCs in CMt supplemented with layers of membrana granulosa and 0.05 IU FSH/ml, resulted in significantly less oocytes that resumed meiosis as compared to culture of COCs in CMt. Of the oocytes that showed GVBD, the proportion that

  4. Epigenetic modification of long interspersed elements-1 in cumulus cells of mature and immature oocytes from patients with polycystic ovary syndrome.

    Science.gov (United States)

    Pruksananonda, Kamthorn; Wasinarom, Artisa; Sereepapong, Wisan; Sirayapiwat, Porntip; Rattanatanyong, Prakasit; Mutirangura, Apiwat

    2016-06-01

    The long interspersed elements (LINE-1, L1s) are a group of genetic elements found in large numbers in the human genome that can translate into phenotype by controlling genes. Growing evidence supports the role of epigenetic in polycystic ovary syndrome (PCOS). The purpose of this study is to evaluate the DNA methylation levels in LINE-1 in a tissue-specific manner using cumulus cells from patients with PCOS compared with normal controls. The study included 19 patients with PCOS and 22 control patients who were undergoing controlled ovarian hyperstimulation. After oocyte retrieval, cumulus cells were extracted. LINE-1 DNA methylation levels were analysed by bisulfite treatment, polymerase chain reaction, and restriction enzyme digestion. The Connection Up- and Down-Regulation Expression Analysis of Microarrays software package was used to compare the gene regulatory functions of intragenic LINE-1. The results showed higher LINE-1 DNA methylation levels in the cumulus cells of mature oocytes in PCOS patients, 79.14 (±2.66) vs. 75.40 (±4.92); p=0.004, but no difference in the methylation of cumulus cells in immature oocytes between PCOS and control patients, 70.33 (±4.79) vs. 67.79 (±5.17); p=0.155. However, LINE-1 DNA methylation levels were found to be higher in the cumulus cells of mature oocytes than in those of immature oocytes in both PCOS and control patients. These findings suggest that the epigenetic modification of LINE-1 DNA may play a role in regulating multiple gene expression that affects the pathophysiology and development of mature oocytes in PCOS.

  5. Anti-Müllerian hormone remains highly expressed in human cumulus cells during the final stages of folliculogenesis

    DEFF Research Database (Denmark)

    Grøndahl, M L; Nielsen, M Eilsø; Dal Canto, M B

    2011-01-01

    , AMH receptor 2, FSH receptor, aromatase and androgen receptor were performed in CC in IVM patients where cumulus-oocyte-complex had expanded, CC in IVM patients where cumulus-oocyte-complex remained compacted, GC from immature follicles and CC and GC from IVF patients. Microarray data on corresponding...

  6. Gene expression microarray profiles of cumulus cells in lean and overweight-obese polycystic ovary syndrome patients.

    Science.gov (United States)

    Kenigsberg, Shlomit; Bentov, Yaakov; Chalifa-Caspi, Vered; Potashnik, Gad; Ofir, Rivka; Birk, Ohad S

    2009-02-01

    The aim of this work was to study gene expression patterns of cultured cumulus cells from lean and overweight-obese polycystic ovary syndrome (PCOS) patients using genome-wide oligonucleotide microarray. The study included 25 patients undergoing in vitro fertilization and intra-cytoplasmic sperm injection: 12 diagnosed with PCOS and 13 matching controls. Each of the groups was subdivided into lean (body mass index (BMI) 27) subgroups. The following comparisons of gene expression data were made: lean PCOS versus lean controls, lean PCOS versus overweight PCOS, all PCOS versus all controls, overweight PCOS versus overweight controls, overweight controls versus lean controls and all overweight versus all lean. The largest number of differentially expressed genes (DEGs), with fold change (FC) |FC| >or= 1.5 and P-value lean PCOS versus lean controls comparison (487) with most of these genes being down-regulated in PCOS. The second largest group of DEGs originated from the comparison of lean PCOS versus overweight PCOS (305). The other comparisons resulted in a much smaller number of DEGs (174, 109, 125 and 12, respectively). In the comparison of lean PCOS with lean controls, most DEGs were transcription factors and components of the extracellular matrix and two pathways, Wnt/beta-catenin and mitogen-activated protein kinase. When comparing overweight PCOS with overweight controls, most DEGs were of pathways related to insulin signaling, metabolism and energy production. The finding of unique gene expression patterns in cumulus cells from the two PCOS subtypes is in agreement with other studies that have found the two to be separate entities with potentially different pathophysiologies.

  7. Bovine cumulus-oocyte disconnection in vitro

    DEFF Research Database (Denmark)

    Maddox-Hyttel, Poul

    1987-01-01

    Cumulus-oocyte complexes were obtained from cows by aspiration of small (1-6 mm in diameter) antral follicles after slaughter. Complexes with a compact multilayered cumulus investment were cultured and processed for transmission electron microscopy after different periods of culture including a 0...... frequency of gap junctions was maintained until 12-18 h of culture where the junctional contact was completely disrupted. This decrease in intercellular communication was parallelled by resumption of oocyte meiosis....

  8. Oocyte polarized light microscopy, assay of specific follicular fluid metabolites, and gene expression in cumulus cells as different approaches to predict fertilization efficiency after ICSI.

    Science.gov (United States)

    Revelli, Alberto; Canosa, Stefano; Bergandi, Loredana; Skorokhod, Oleksii A; Biasoni, Valentina; Carosso, Andrea; Bertagna, Angela; Maule, Milena; Aldieri, Elisabetta; D'Eufemia, Maria Diletta; Evangelista, Francesca; Colacurci, Nicola; Benedetto, Chiara

    2017-06-23

    The complex relationship between oocyte morphology, specific follicular fluid metabolites, gene expression in cumulus granulosa cells, and oocyte competence toward fertilization and embryo development still needs further clarification. Forty-six oocytes retrieved from the largest pre-ovulatory follicle of patients undergoing intra-cytoplasmic sperm injection (ICSI) were considered assessing: (a) oocyte morphological characteristics at polarized light microscopy (PLM), (b) specific follicular fluid (FF) metabolites previously suggested to influence oocyte competence (AMH, markers of redox status and of cytotoxicity), (c) transcription of AMH and AMH type II receptor genes in cumulus cells. Data were analyzed using mono-parametric tests and multivariable logistic analysis in order to correlate morphological and biochemical data with fertilization. Comparing normally fertilized oocytes (n = 29, F group) with unfertilized (n = 17, nF group) we observed that: (a) the meiotic spindle area and major axis were significantly higher in nF group and in fertilized oocytes undergoing an early embryo development arrest; (b) AMH level in FF was comparable in F and nF groups; (c) the FF of nF group contained significantly higher levels of cytotoxicity (lactate dehydrogenase) and oxidative stress (Cu,Zn-superoxide dismutase, catalase, 4-hydroxynonenal-protein conjugates) markers; (d) cumulus cells of nF group showed significantly higher AMH receptor type II gene expression. Taken together, these observations suggest that an excessive cytotoxicity level can alter AMH signal transduction within cumulus cells, in turn leading to partial inhibition of aromatase activity, altered cytoplasmic maturation and increased oxidative stress, factors able to impair oocyte fertilization competence and embryo growth.

  9. Steroidogenesis during in vitro maturation of bovine cumulus oocyte complexes and possible effects of tri-butyltin on granulosa cells.

    Science.gov (United States)

    Schoenfelder, M; Schams, D; Einspanier, R

    2003-02-01

    Steroids are known as important factors on the route of oocytes development and cumulus oocyte complexes (COC) as well as follicular granulosa cells (GC) are suggested to be themselves involved in steroidogenesis. The aim of this study was to characterize such a local sex steroidogenic system during in vitro maturation (IVM) of bovine COCs according to the production of estradiol (E), testosterone (T) and progesterone (P). The expression of two steroid-converting key-enzymes was measured in parallel by quantitative RT-PCR. Furthermore, possible effects of the environmental pollutant tri-butyltin (TBT) were elucidated for the first time on bovine COC and GC in vitro concerning that steroidogenic system. During IVM of bovine COCs concentrations of P increased continuously, corresponding with steady-state levels of 3-beta-hydroxy-steroid-dehydrogenase (HSD) transcripts. In contrast, E together with P450 aromatase mRNA (ARO) increased in the first hours of IVM but declining thereafter, whereas T reached almost balanced levels. However, TBT showed only slight effects during IVM of COC. In cultured GC, LH caused highest P- and E-production within 24h and treatment with 50pM TBT induced a significant decrease of E in contrast to 100pM TBT and the control. These results indicate, that (1) COCs were able to modulate their steroidogenic environment in vitro and that (2) TBT may possibly influence or disturb steroidogenesis in the cows reproductive tract shown here for GC.

  10. Influence of FSH and hCG on the resumption of meiosis of bovine oocytes surrounded by cumulus cells connected to membrana granulosa.

    Science.gov (United States)

    van Tol, H T; van Eijk, M J; Mummery, C L; van den Hurk, R; Bevers, M M

    1996-10-01

    Cumulus oocyte complexes (COCs) and cumulus oocyte complexes connected to a piece of the membrane granulosa (COCGs) were isolated from bovine antral follicles with a diameter of 2 to 8 mm. After culture of COCGs without gonadotrophic hormones for 22 hr approximately 50% of the oocytes were still in the germinal vesicle (GV) stage. Histology of the COCGs showed that the pieces of the membrana granulosa were free of thecal cells and parts of the basal membrane. This indicates that the membrana granulosa solely inhibits the progression of meiosis. To investigate the effect of gonadotropins on the resumption of meiosis of oocytes from small and medium sized antral follicles, COCs and COCGs were cultured with or without rec-hFSH or hCG. Addition of 0.05 IU rec-hFSH to the culture medium of COCGs resulted in germinal vesicle breakdown in 97.8% of the oocytes compared to 46% in the control group, and an increase of the diameter of the COCs (479 microns vs. 240 microns in the control group). Addition of 0.05 IU hCG to the culture medium had no effect on nuclear maturation (47.2% GV vs. 48.5% GV in the control group) nor on cumulus expansion (246 microns vs. 240 microns in the control group). RT-PCR on cDNA of the follicular wall, cumulus cells, granulosa cells, COCs, and oocytes revealed that mRNA for FSH receptor was present in all cell types except oocytes. mRNA of the LH receptor was detected exclusively in thecal cells. Nucleotide sequence analysis and alignment of the cloned PCR products showed the presence of two isoforms of the FSH receptor mRNA and two isoforms of the LH receptor mRNA. It is concluded that, in vitro, resumption of meiosis of oocytes, originating from small and medium sized antral follicles and meiotically arrested by the membrana granulosa, is triggered by FSH and not by LH. This is supported by the fact that receptors for FSH, but not for LH, are transcribed in the cumulus and granulosa cells of these follicles.

  11. In vitro and in vivo studies reveal that hamster oocyte meiotic arrest is maintained only transiently by follicular fluid, but persistently by membrana/cumulus granulosa cell contact.

    Science.gov (United States)

    Racowsky, C; Baldwin, K V

    1989-08-01

    Studies were carried out with the golden Syrian hamster to investigate the capacity of follicular fluid to maintain oocyte meiotic arrest and to determine the importance of cumulus-membrana granulosa cell contact in the regulation of meiotic status. The follicular fluid studies were conducted by cytological assessment of meiotic stage up to 6 hr after transferring cumulus-free oocytes into antra of explanted "host" follicles in vitro or into follicles of anesthetized animals prior to the gonadotropin surge at proestrus in vivo. The cumulus-membrana granulosa contact studies were undertaken with explanted follicles in which the oocyte-cumulus complex was dislodged from the underlying membrana granulosa, released into the antrum, and subsequently allowed to reestablish contact during 6 hr of incubation within the follicle. The extent of recontact of the dislodged complex with the underlying membrana granulosa was assessed visually at the end of incubation and was classified as close, moderate, or none. These various degrees of contact typically involved the following number of cumulus cells, as determined by serial sectioning of a representative sample of follicles after dislodgement and subsequent incubation: close, 32.7 +/- 1.78; moderate, 9.0 +/- 2.1; and no contact, 0. After 6 hr of incubation either in vitro or in vivo, few transferred oocytes remained at the germinal vesicle (GV) stage (18.8 +/- 8.7 and 17.3 +/- 4.0% GV, respectively). However, time course experiments revealed that meiotic resumption was significantly delayed in transferred oocytes compared with either liberated oocytes, spontaneously maturing oocytes, or follicle-enclosed oocytes induced to mature by luteinizing hormone in vitro (after 4 hr, transferred, 31.3 +/- 6.0% GV; liberated, 0% GV; follicle-enclosed, 0% GV; after 6 hr, 0% transferred oocytes exhibited a GV). In the dislodgement studies, after 6 hr of incubation, 26% of complexes reestablished close contact with the underlying membrana

  12. Fibroblast Growth Factors and Epidermal Growth Factor Cooperate with Oocyte-Derived Members of the TGFbeta Superfamily to Regulate Spry2 mRNA Levels in Mouse Cumulus Cells1

    Science.gov (United States)

    Sugiura, Koji; Su, You-Qiang; Li, Qinglei; Wigglesworth, Karen; Matzuk, Martin M.; Eppig, John J.

    2009-01-01

    Mouse oocytes produce members of the transforming growth factor beta (TGFbeta) superfamily, including bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9), as well as fibroblast growth factors (FGFs). These growth factors cooperate to regulate cumulus cell function. To identify potential mechanisms involved in these interactions, the ability of fully grown oocytes to regulate expression of BMP or FGF antagonists in cumulus cells was examined. Oocytes promoted cumulus cell expression of transcripts encoding antagonists to TGFbeta superfamily members, including Grem2, Htra1, Htra3, and Nog mRNAs. In contrast, oocytes suppressed cumulus cell expression of Spry2 mRNA, which encodes a regulator of receptor tyrosine kinase signals, such as FGF and epidermal growth factor (EGF) receptor signals. The regulation of Spry2 mRNA levels in cumulus cells was studied further as a model for analysis of potential mechanisms for cooperativity of FGF/EGF signaling with oocyte-derived members of the TGFbeta superfamily. Oocytes suppressed basal and FGF-stimulated Spry2 mRNA levels in cumulus cells but promoted EGF-stimulated levels. Furthermore, recombinant TGFbeta superfamily proteins, including BMP15 and GDF9, mimicked these effects of oocytes. Elevated expression of Spry2 mRNA in cumulus and mural granulosa cells correlated with human chorionic gonadotropin-induced expression of mRNAs encoding EGF-like peptides. Therefore, oocyte-derived members of the TGFbeta superfamily suppress FGF-stimulated Spry2 mRNA levels before the luteinizing hormone surge but promote Spry2 mRNA levels stimulated by EGF receptor-mediated signals after the surge. PMID:19553596

  13. miR-483-5p and miR-486-5p are down-regulated in cumulus cells of metaphase II oocytes from women with polycystic ovary syndrome.

    Science.gov (United States)

    Shi, Lin; Liu, Shan; Zhao, Wanqiu; Shi, Juanzi

    2015-10-01

    The aim of this study was to compare the expression of microRNAs (miRNAs) in cumulus cells from polycystic ovary syndrome (PCOS) and non-PCOS women. In the present study, miRNA expression profiles of the cumulus cell samples were determined by miRNA microarrays. Quantification of selected miRNAs and predicted target genes was performed using quantitative real-time PCR (qRT-PCR). The results showed that miR-483-5p and miR-486-5p are significantly decreased in cumulus cells of PCOS patients PCOS (fold change >2, false discovery rate <0.001). qRT-PCR found that four predicted genes, SOCS3, SRF, PTEN and FOXO1, were significantly increased in PCOS cumulus cells (all P < 0.001), and IGF2 (host gene of miR-483-5p) was significantly decreased in PCOS cumulus cells (P < 0.001). These results indicated that miR-483-5p might play an important role in reducing insulin resistance, and that miR-486-5p might promote cumulus cell proliferation through activation of PI3K/Akt. The findings from this study provided new insights into the complex molecular mechanisms involved in PCOS by revealing pathways possibly regulated by miRNAs. The differences in miRNAs (miR-483-5p, miR-486-5p) and their target gene expression in cumulus cells may provide clues for future research and help to explain aberrant follicular development and subfertility in women with PCOS.

  14. LH-receptor gene expression in human granulosa and cumulus cells from antral and preovulatory follicles

    DEFF Research Database (Denmark)

    Jeppesen, Janni Vikkelsø; Kristensen, Stine Gry; Nielsen, Maria Eilsø

    2012-01-01

    frozen and patients undergoing infertility treatment. Interventions: Cells and fluids were isolated from surgically excised ovaries or from aspirated preovulatory follicles. Main Outcome Measures: We evaluated gene expression of LHR, FSHR, androgen receptor (AR), aromatase (CYP19a1), and AMHR2 normalized...... to the GAPDH expression and associated with FF levels of anti-Mullerian hormone, inhibin-B, and steroids. Results: LHR expression was maximal in GC from preovulatory follicles before ovulation induction. A majority of 150 antral follicles (3-10 mm in diameter) showed LHR expression at approximately 10...

  15. Motility contrast imaging of live porcine cumulus-oocyte complexes

    Science.gov (United States)

    An, Ran; Turek, John; Machaty, Zoltan; Nolte, David

    2013-02-01

    Freshly-harvested porcine oocytes are invested with cumulus granulosa cells in cumulus-oocyte complexes (COCs). The cumulus cell layer is usually too thick to image the living oocyte under a conventional microscope. Therefore, it is difficult to assess the oocyte viability. The low success rate of implantation is the main problem for in vitro fertilization. In this paper, we demonstrate our dynamic imaging technique called motility contrast imaging (MCI) that provides a non-invasive way to monitor the COCs before and after maturation. MCI shows a change of intracellular activity during oocyte maturation, and a measures dynamic contrast between the cumulus granulosa shell and the oocytes. MCI also shows difference in the spectral response between oocytes that were graded into quality classes. MCI is based on shortcoherence digital holography. It uses intracellular motility as the endogenous imaging contrast of living tissue. MCI presents a new approach for cumulus-oocyte complex assessment.

  16. Participation of Mitogen-activated Protein Kinase in Luteinizing Hormone-induced Differential Regulation of Steroidogenesis and Steroidogenic Gene Expression in Mural and Cumulus Granulosa Cells of Mouse Preovulatory Follicles

    DEFF Research Database (Denmark)

    Su, You-Qiang; Nyegaard, Mette; Overgaard, Michael Toft;

    2006-01-01

    was to investigate whether these processes that commonly occur in mural granulosa cells (MGCs) also occur in cumulus cells, and whether they are mediated by the mitogen-activated protein kinase (MAPK), specifically MAPK3/1 (also commonly known as extracellular signal-regulated kinase 1&2, ERK1/2). The standard...

  17. Identification of altered microRNAs and mRNAs in the cumulus cells of PCOS patients: miRNA-509-3p promotes oestradiol secretion by targeting MAP3K8.

    Science.gov (United States)

    Huang, Xin; Liu, Chang; Hao, Cuifang; Tang, Qianqing; Liu, Riming; Lin, Shaoxia; Zhang, Luping; Yan, Wei

    2016-06-01

    Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women and is characterised by polycystic ovaries, hyperandrogenism and chronic anovulation. Although the clinical and biochemical signs of PCOS are typically heterogeneous, abnormal folliculogenesis is considered a common characteristic of PCOS. Our aim is to identify the altered miRNA and mRNA expression profiles in the cumulus cells of PCOS patients to investigate their molecular function in the aetiology and pathophysiology of PCOS. In this study, the miRNA expression profiles of the cumulus cell samples isolated from five PCOS and five control patients were determined by an miRNA microarray. At the same time, the altered mRNA profiles of the same cumulus cell samples were also identified by a cDNA microarray. From the microarray data, 17 miRNAs and 1263 mRNAs showed significantly different expression in the PCOS cumulus cells. The differentially expressed miRNA-509-3p and its potential target gene (MAP3K8) were identified from the miRNA and mRNA microarrays respectively. The expression of miRNA-509-3p was up-regulated and MAP3K8 was down-regulated in the PCOS cumulus cells. The direct interaction between miRNA-509-3p and MAP3K8 was confirmed by a luciferase activity assay in KGN cells. In addition, miRNA-509-3p mimics or inhibitor transfection tests in KGN cells further confirmed that miRNA-509-3p improved oestradiol (E2) secretion by inhibiting the expression of MAP3K8 These results help to characterise the pathogenesis of anovulation in PCOS, especially the regulation of E2 production.

  18. Cumulus cells gene expression profiling in terms of oocyte maturity in controlled ovarian hyperstimulation using GnRH agonist or GnRH antagonist.

    Directory of Open Access Journals (Sweden)

    Rok Devjak

    Full Text Available In in vitro fertilization (IVF cycles controlled ovarian hyperstimulation (COH is established by gonadotropins in combination with gonadotropin-releasing hormone (GnRH agonists or antagonists, to prevent premature luteinizing hormone (LH surge. The aim of our study was to improve the understanding of gene expression profile of cumulus cells (CC in terms of ovarian stimulation protocol and oocyte maturity. We applied Affymetrix gene expression profiling in CC of oocytes at different maturation stages using either GnRH agonists or GnRH antagonists. Two analyses were performed: the first involved CC of immature metaphase I (MI and mature metaphase II (MII oocytes where 359 genes were differentially expressed, and the second involved the two GnRH analogues where no differentially expressed genes were observed at the entire transcriptome level. A further analysis of 359 differentially genes was performed, focusing on anti-Müllerian hormone receptor 2 (AMHR2, follicle stimulating hormone receptor (FSHR, vascular endothelial growth factor C (VEGFC and serine protease inhibitor E2 (SERPINE2. Among other differentially expressed genes we observed a marked number of new genes connected to cell adhesion and neurotransmitters such as dopamine, glycine and γ-Aminobutyric acid (GABA. No differential expression in CC between the two GnRH analogues supports the findings of clinical studies where no significant difference in live birth rates between both GnRH analogues has been proven.

  19. Exposure of pig oocytes to PCBs during in vitro maturation: effects on developmental competence, cytoplasmic remodelling and communications with cumulus cells

    Directory of Open Access Journals (Sweden)

    TAL Brevini

    2009-06-01

    Full Text Available Polychlorinated biphenyls (PCBs are one of the most persistent and widespread groups of endocrine disrupting compounds in the ecosystem. These substances are present in sewage sludge that is spread in increasing amounts on arable land and pasture as fertilizer, and are ingested by farm animals with food and drinking water. This study investigated the effect of different PCB concentrations on pig oocyte in vitro maturation and developmental competence as well as examined the possible mechanisms involved. A concentration ranging from 0 to 1 ?g/mL of Aroclor 1254 (A1254, a pool of more than 60 PCB congeners, was added to the maturation medium, as its composition is considered environmentally relevant. A1254 had no effect on maturation of pig oocytes and on the number of oocytes that cleaved following parthenogenetic activation at any of the doses tested. By contrast, a significant decrease in the number of zygotes that developed to blastocyst stage became evident at a concentration of 10 ng/mL. The number of blastocysts obtained decreased significantly, and in a dose response manner with higher concentrations. Exposure to PCBs altered mitochondria relocation during maturation and this was associated with the lack of a cytoplasmic microtubule network. No effect on mitochondria activity was observed. A1254 exposure also perturbed gap-junction mediated communications between oocytes and cumulus cells. In conclusion, PCB exposure of pig oocytes during in vitro maturation significantly decreased oocyte developmental competence, altered both their cytoplasmic remodelling and the communication with the somatic compartment. These data indicated that accumulation of PCBs in the pig organism may have a detrimental effect on the reproductive efficiency in this species.

  20. Culture of porcine luteal cells as a substrate for in vitro maturation of porcine cumulus oocyte complexes. Establishment and characterization

    Directory of Open Access Journals (Sweden)

    Teplitz MA

    2016-12-01

    Full Text Available The aim of this study was to establish and characterize the porcine luteal cells (PLC culture for the subsequent coculture with porcine COC. The final purpose is to promote the oocyte maturation. The PLC was established using corpora lutea obtained from slaughterhouse ovaries. Corpora lutea were dissected and luteal tissue submitted to a mechanical and enzymatic digestion with collagenase IV. The cell suspension was filtered and centrifuged and the cells obtained were diluted in 15 mL of DMEM-F12 supplemented media. Diluted cells were seeded in 3 culture flasks T25, staying in a controlled environment and changing the medium every 2 days. For the analysis and characterization, the cells were assessed by the Nile red staining to detect intracellular lipids, immunocytochemistry (ICC for 3β-hydroxy steroid dehidrogenase (3β-HSD and ELISA for P4 determination. We observed the presence of lipid intracellular droplets. Also, we observed an increase of P4 concentration at 48, 96 y 144 h of primary culture and almost all the cells were positive to the ICC evaluation for 3β-HSD, showing the steroidogenic capacity of the culture cells.

  1. 人卵丘细胞与卵子发育潜能关系的研究进展%Research Progress of the Relationship between Human Cumulus Cells and Oocyte Developmental Potential

    Institute of Scientific and Technical Information of China (English)

    叶田

    2013-01-01

    人卵丘细胞与卵母细胞之间存在密切联系,前者可以直接影响后者的发育、成熟以及所形成胚胎的质量.在辅助生殖技术中,通过对卵丘细胞的研究,可以为胚胎选择提供更加客观、准确且无创的方法,提高妊娠率,推动选择性单胚胎移植的发展,减少高序多胎妊娠及其所带来的不良妊娠结局.目前,从基因及转录水平探讨卵丘细胞与卵子质量的关系已成为研究热点.研究表明,卵丘细胞中卵母细胞发育相关基因表达上调能够预测优质胚胎;细胞周期检测点及DNA修复相关基因与卵子质量有关;细胞凋亡、葡萄糖生成、抗氧化应激相关基因及核转录因子I/B是预测卵子发育潜能和妊娠结局的生物学指标.%There is a close relationship between human cumulus granulosa cells and oocytes,because the former could influence the development and maturation of oocytes and therefore the embryos quality.In assisted reproductive technology,study on cumulus granulosa cells may offer us more objective,accurate and noninvasive criteria for embryo selection so that the pregnancy rates can be increased and the elective single embryo transfer protocol can be promoted.On the other hand,the high order multiple pregnancy rates and the poor outcomes can be also decreased considerably.Nowadays,it is a hot area to explore the relationship between cumulus cells and oocyte developmental potential at the genetic and transcriptional levels.It was reported that the up-regulation of oogenesis-related genes in cumulus cells can predict good quality embryos.Checkpoints and DNA repair-related genes are associated with oocyte quality.Cell apoptosis,glucogenesis,antioxidative stressrelated genes and transcription factor NFIB are the biological parameters to predict the oocyte developmental potential and pregnancy outcome.

  2. Electron Transfer Pathways in Cell

    OpenAIRE

    Yan Liu

    2012-01-01

    Analysis of the electron salvation process data indicates that the electron transfer between the electron donor and acceptor is hindered by the electron salvation process. It is proposed that the electron transfer in the cell environment must be assisted by intermediate messenger called the “transport protein”.

  3. Visualizing Cumulus Clouds in Virtual Reality

    NARCIS (Netherlands)

    Griffith, E.J.

    2010-01-01

    This thesis focuses on interactively visualizing, and ultimately simulating, cumulus clouds both in virtual reality (VR) and with a standard desktop computer. The cumulus clouds in question are found in data sets generated by Large-Eddy Simulations (LES), which are used to simulate a small section

  4. Visualizing Cumulus Clouds in Virtual Reality

    NARCIS (Netherlands)

    Griffith, E.J.

    2010-01-01

    This thesis focuses on interactively visualizing, and ultimately simulating, cumulus clouds both in virtual reality (VR) and with a standard desktop computer. The cumulus clouds in question are found in data sets generated by Large-Eddy Simulations (LES), which are used to simulate a small section o

  5. 人卵丘细胞内基因表达与胚胎发育潜能的关系%Expressions of Some Genes in Human Cumulus Cell Related to Developmental Potential of Embryo

    Institute of Scientific and Technical Information of China (English)

    鲍晓; 徐家伟; 孙莹璞

    2015-01-01

    缺乏准确、客观、非侵入性的胚胎评估标准是目前体外受精-胚胎移植技术所面临的主要挑战之一。本文对卵丘细胞内基因表达与胚胎及卵子发育潜能之间的相关研究进行了总结,发现卵丘细胞内特定基因的表达与胚胎发育、成熟及发育潜能之间存在紧密的联系。近年来,通过实时定量逆转录聚合酶链反应(qRT-PCR)及微阵列技术筛选出一系列颗粒细胞中能够预测受精结局、胚胎形态学评分、妊娠结局等胚胎发育潜能的候选标记基因,这些基因主要涉及卵丘扩展、脂类代谢、细胞凋亡等过程。然而,卵母细胞及胚胎的发育受卵泡内、外多种因素的影响。欲确立一种全面、准确、非侵入性的胚胎发育潜能评估方法仍需更深入的研究。%One of the major challenges in in-vitro fertilization-embryo transfer (IVF-ET) technology is lack of an objective, accurate, noninvasive criteria for evaluating the developmental potential of embryo. We reviewed here the expressions of those genes in cumulus cells related to the developmental potential of oocyte, suggesting that there was a close relationship between the expression of some specific genes in human cumulus cells and oocyte development, maturation, and embryo developmental potential. Recently, using qRT-PCR and microarray technologies, a series of candidate genes in cumulus and granulosa cells were found to be possible markers to predict the developmental potential of embryo, such as those genes related to cumulus expansion, lipid metabolism, cell apoptosis and other aspects, which could be useful to predict fertilization outcomes, embryo morphology and pregnant outcomes. However, the development of oocyte and embryo could be affected by various factors. It is necessary to do more detailed study to develop a accurate, comprehensive and non-invasive test for evaluating the developmental potential of oocyte and embryo.

  6. Partial characterization of the factor in theca-cell conditioned medium that inhibits the progression of FSH-induced meiosis of bovine oocytes surrounded by cumulus cells connected to the membrana granulosa.

    Science.gov (United States)

    van Tol, H T; Bevers, M M

    2001-11-01

    A factor, secreted by theca cells, inhibits FSH induced resumption of meiosis in bovine oocytes that are surrounded by cumulus cells which are attached to a piece of the membrana granulosa (COCGs). In order to characterize this factor, theca cell conditioned medium (CMt) was heat-treated, filtered through a 5 kD spin off filter, charcoal treated, chloroform extracted and protease treated. To investigate whether the meiosis inhibiting factor produced by theca cells was also present in follicular fluid (FF), the same treatments were done with 50% bovine follicular fluid (bFF). COCGs, originating from 2 to 8 mm follicles of bovine ovaries collected at a slaughterhouse, were cultured in groups of 15 per 600 microl medium supplemented with 0.05 IU ml FSH for 22 hr at 39 degrees C in a humidified atmosphere of 5% CO(2). After culture the oocytes were denuded, stained with orcein, and the nuclear status assessed. Heat treatment did not affect the meiosis arresting capacity of CMt since a similar proportion of the oocytes remained at the GV stage after 22 hr of culture in heat treated CMt as compared to the proportion of oocytes in the GV stage after culture in untreated CMt. Filtering through a 5 kD spin-off filter revealed that the meiosis inhibiting action was maintained in the <5 kD fraction, although there was a significant (P < 0.05) loss of inhibiting activity compared to nonfiltered CMt. No significant decrease was observed in the meiosis arresting capacity of the <5 kD fraction after charcoal or protease treatment. Extraction of the <5 kD fraction with chloroform also did not affect the theca cell produced factor. The effect of the theca cell factor on the progression of meiosis of the oocytes that resumed meiosis, as demonstrated by a very low percentage of the oocytes that matured up to the M2 stage, was not affected following any of the treatments. With regard to bFF, the results show a lower percentage of the oocytes in the GV stage after culture in 50% bFF as

  7. Electronic Interfacing with Living Cells

    Science.gov (United States)

    Fleming, James T.

    The direct interfacing of living cells with inorganic electronic materials, components or systems has led to the development of two broad categories of devices that can (1) transduce biochemical signals generated by biological components into electrical signals and (2) transduce electronically generated signals into biochemical signals. The first category of devices permits the monitoring of living cells, the second, enables control of cellular processes. This review will survey this exciting area with emphasis on the fundamental issues and obstacles faced by researchers. Devices and applications that use both prokaryotic (microbial) and eukaryotic (mammalian) cells will be covered. Individual devices described include microbial biofuel cells that produce electricity, bioelectrical reactors that enable electronic control of cellular metabolism, living cell biosensors for the detection of chemicals and devices that permit monitoring and control of mammalian physiology.

  8. Liquid Cell Transmission Electron Microscopy

    Science.gov (United States)

    Liao, Hong-Gang; Zheng, Haimei

    2016-05-01

    Liquid cell transmission electron microscopy (TEM) has attracted significant interest in recent years. With nanofabricated liquid cells, it has been possible to image through liquids using TEM with subnanometer resolution, and many previously unseen materials dynamics have been revealed. Liquid cell TEM has been applied to many areas of research, ranging from chemistry to physics, materials science, and biology. So far, topics of study include nanoparticle growth and assembly, electrochemical deposition and lithiation for batteries, tracking and manipulation of nanoparticles, catalysis, and imaging of biological materials. In this article, we first review the development of liquid cell TEM and then highlight progress in various areas of research. In the study of nanoparticle growth, the electron beam can serve both as the illumination source for imaging and as the input energy for reactions. However, many other research topics require the control of electron beam effects to minimize electron beam damage. We discuss efforts to understand electron beam-liquid matter interactions. Finally, we provide a perspective on future challenges and opportunities in liquid cell TEM.

  9. Role of Fas-Mediated Apoptosis and Follicle-Stimulating Hormone on the Developmental Capacity of Bovine Cumulus Oocyte Complexes in Vitro

    NARCIS (Netherlands)

    Pomar, F.J.; Roelen, B.A.J.; Slot, K.A.; Tol, van H.T.A.; Colenbrander, B.; Teerds, K.J.

    2004-01-01

    Follicular atresia is believed to be largely regulated by apoptosis. To further understand how apoptosis can affect cumulus cells and oocytes we have evaluated the incidence and regulation of apoptosis affecting bovine cumulus oocyte complexes in vitro. Expression of components of the Fas signaling

  10. Time course of the meiotic arrest in sheep cumulus-oocyte complexes treated with roscovitine.

    Science.gov (United States)

    Crocomo, Letícia Ferrari; Marques Filho, Wolff Camargo; Ackermann, Camila Louise; Paschoal, Daniela Martins; Guastali, Midyan Daroz; Dias Maziero, Rosiára Rosária; Sudano, Mateus José; Landim-Alvarenga, Fernanda da Cruz; Bicudo, Sony Dimas

    2016-04-01

    Temporary meiosis arrest with cyclin-dependent kinases inhibitors has been proposed in order to improve the quality of in vitro matured oocytes. In sheep, however, this phenomenon has been rarely investigated. Therefore, the present study aimed to evaluate the effect of different incubation times with roscovitine on nuclear maturation and cumulus cell expansion of sheep cumulus-oocyte complexes (COCs). For this, COCs were cultured for 0, 6, 12 or 20 h in basic maturation medium (Control) containing 75 μM roscovitine (Rosco). After, they were in vitro matured (IVM) for 18 h in the presence of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). At the end of each treatment, cumulus cell expansion and nuclear maturation were assessed under a stereomicroscope and by Hoechst 33342 staining, respectively. In the Control and Rosco groups, the absence of cumulus cell expansion prevailed at 0, 6, 12 and 20 h. After IVM for 18 h, total cumulus cell expansion in the Rosco treatments was dependent on the exposure time to roscovitine. A significantly high percentage of oocytes treated with roscovitine for 6 h (87%), 12 h or 20 h (65%) were arrested at the germinal vesicle (GV) stage. In contrast, 23% GVBD, 54% metaphase I (MI) and 61% MII oocytes were observed in the Control groups at 6, 12 and 20 h, respectively. In all treatments, a significant percentage of oocytes reached MII after IVM for 18 h. Therefore, roscovitine reversibly arrested the meiosis of sheep oocytes during different culture times with the maximal efficiency of meiotic inhibition reached at 6 h. In addition, reversibility of its inhibitory action on cumulus cells was exposure-time dependent.

  11. Cumulus convection and the terrestrial water-vapor distribution

    Science.gov (United States)

    Donner, Leo J.

    1988-01-01

    Cumulus convection plays a significant role in determining the structure of the terrestrial water vapor field. Cumulus convection acts directly on the moisture field by condensing and precipitating water vapor and by redistributing water vapor through cumulus induced eddy circulations. The mechanisms by which cumulus convection influences the terrestrial water vapor distribution is outlined. Calculations using a theory due to Kuo is used to illustrate the mechanisms by which cumulus convection works. Understanding of these processes greatly aids the ability of researchers to interpret the seasonal and spatial distribution of atmospheric water vapor by providing information on the nature of sources and sinks and the global circulation.

  12. Sources of cumulus expansion enabling factor (CEEF) in porcine follicles

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    It was shown that expansion of porcine cumulus did not depend on oocyte-secreted factor(s), and it is therefore presumed that porcine CEEF may not be produced exclusively by the oocyte. In this experiment, we used mouse oocytectomized complexes (OOX), which were incapable of CEEF production, to assess the secretion of CEEF by evacuated zona, oocytes of different quality and somatic cells in the porcine follicles. The results showed that: (ⅰ) Evacuated zonae from both porcine and mouse oocytes did not produce CEEF. (ⅱ) Porcine oocytes of A, B and C types from 3 - 6 mm follicles were not significantly different in both production and activity of CEEF. (ⅲ) Both porcine OOX from 3 - 6 mm follicles and granulose cells from < 1 mm follicles secreted CEEF in a large quantity, independent of gonadotropins; mural granulose cells from 3-6 mm follicles, however, produced neglectable amount of CEEF. (ⅳ) The follicular fluid from 3-6 mm porcine follicles contained CEEF activity that was concentration-dependent, and thus it enabled cumulus expansion in 60% mouse OOX when used at 10% of concentration, but the expansion rate of mouse OOX decreased to 9% when the concentration was increased to 50%. (ⅴ) Mouse OOX cultured in porcine CEEF-containing M199 expanded only in the presence of gonadotropins, suggesting that the activity of porcine CEEF is hormone-de- pendent.

  13. Mouse Oocytes Enable LH-Induced Maturation of the Cumulus-Oocyte Complex via Promoting EGF Receptor-Dependent Signaling

    Science.gov (United States)

    Su, You-Qiang; Sugiura, Koji; Li, Qinglei; Wigglesworth, Karen; Matzuk, Martin M.; Eppig, John J.

    2010-01-01

    LH triggers the maturation of the cumulus-oocyte complex (COC), which is followed by ovulation. These ovarian follicular responses to LH are mediated by epidermal growth factor (EGF)-like growth factors produced by granulosa cells and require the participation of oocyte-derived paracrine factors. However, it is not clear how oocytes coordinate with the EGF receptor (EGFR) signaling to achieve COC maturation. The aim of the present study was to test the hypothesis that oocytes promote the expression of EGFR by cumulus cells, thus enabling them to respond to the LH-induced EGF-like peptides. Egfr mRNA and protein expression were dramatically reduced in cumulus cells of mutant mice deficient in the production of the oocyte-derived paracrine factors growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15). Moreover, microsurgical removal of oocytes from wild-type COCs dramatically reduced expression of Egfr mRNA and protein, and these levels were restored by either coculture with oocytes or treatment with recombinant GDF9 or GDF9 plus recombinant BMP15. Blocking Sma- and Mad-related protein (SMAD)2/3 phosphorylation in vitro inhibited Egfr expression in wild-type COCs and in GDF9-treated wild-type cumulus cells, and conditional deletion of Smad2 and Smad3 genes in granulosa cells in vivo resulted in the reduction of Egfr mRNA in cumulus cells. These results indicate that oocytes promote expression of Egfr in cumulus cells, and a SMAD2/3-dependent pathway is involved in this process. At least two oocyte-derived growth factors, GDF9 and BMP15, are required for EGFR expression by cumulus cells. PMID:20382892

  14. Participation of Mitogen-activated Protein Kinase in Luteinizing Hormone-induced Differential Regulation of Steroidogenesis and Steroidogenic Gene Expression in Mural and Cumulus Granulosa Cells of Mouse Preovulatory Follicles

    DEFF Research Database (Denmark)

    Su, You-Qiang; Nyegaard, Mette; Overgaard, Michael Toft

    2006-01-01

    superovulation model for premature female mice was used to obtain MGCs and cumulus-oocyte complexes (COCs), and sensitive real-time reverse transcription polymerase chain reaction was used to simultaneously detect the expression levels of transcripts encoding key steroidogenic enzymes in the same sample. We...

  15. ELECTRON BOMBARDMENT OF SILICON SOLAR CELLS,

    Science.gov (United States)

    DAMAGE, ELECTRON IRRADIATION, SOLAR CELLS , SILICON, PHOTOELECTRIC CELLS(SEMICONDUCTOR), QUARTZ, GLASS, SHIELDING, CRYSTAL DEFECTS, HEAT TREATMENT, ARTIFICIAL SATELLITES, SPACECRAFT, GRAPHICS, GRAPHICS.

  16. Roles of trifluoperazine and verapamil in the oocyte maturation and cumulus expansion of bovine cumulus—oocyte complexes

    Institute of Scientific and Technical Information of China (English)

    SunQingyuan; FengHuailiang; 等

    1994-01-01

    Bovine cumulus-oocyte complexes were cultured in the maturation medium containing 4 different concentrations of verapamil and trifluoperazine to testify the necessity of extracellular Ca2+ and Ca2+-calmodulin complex for the resumption and completion of meiosis as well as cumulus expansion.Ultrastructure of the treated oocytes was also observed to investigate the cytoplasm maturation.The results showed that verapamil didn't influence the cumulus expansion,meiosis resumption and completion and cytoplasm maturation significantly.TFP inhibited cumulus expansion in a dose-dependent manner.25um trifluoperazine significantly inhibited the GVBD and maturation (P<0.01),wherease 1um TFP had no effect,Both oocytes and cumulus cells treated with 25um TFP severely degenerated.Our observtions suggest that the resumption and completion of meiosis and cumulus expansion are Ca2+-CaM dependent and blocking membrane Ca2+ channel does not influence oocyte germinal vesicle breakdown,nuclear and cytoplasm maturation significantly in cattle.

  17. Sky cover from MFRSR observations: cumulus clouds

    Directory of Open Access Journals (Sweden)

    E. Kassianov

    2011-01-01

    Full Text Available The diffuse all-sky surface irradiances measured at two nearby wavelengths in the visible spectral range and their model clear-sky counterparts are two main components of a new method for estimating the fractional sky cover of different cloud types, including cumulus clouds. The performance of this method is illustrated using 1-min resolution data from ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR. The MFRSR data are collected at the US Department of Energy Atmospheric Radiation Measurement (ARM Climate Research Facility (ACRF Southern Great Plains (SGP site during the summer of 2007 and represent 13 days with cumulus clouds. Good agreement is obtained between estimated values of the fractional sky cover and those provided by a well-established independent method based on broadband observations.

  18. Impacts of Cumulus Momentum Transport on MJO Simulation

    Institute of Scientific and Technical Information of China (English)

    LING Jian; LI Chongyin; JIA Xiaolong

    2009-01-01

    Vertical cumulus momentum transport is an important physical process in the tropical atmosphere and plays a key role in the evolution of the tropical atmospheric system.This paper focuses on the impact of the vertical cumulus momentum transport on Madden-Julian Oscillation (MJO) simulation in two global climate models (GCMs).The Tiedtke cumulus parameterization scheme is applied to both GCMs [CAM2 and Spectral Atmospheric general circulation Model of LASG/IAP (SAMIL)].It is found that the MJO simulation ability might be influenced by the vertical cumulus momentum transport through the cumulus parameterization scheme.However,the use of vertical momentum transport in different models provides different results.In order to improve model's MJO simulation ability,we must introduce vertical cumulus momentum transport in a more reasonable way into models.Furthermore,the coherence of the parameterization and the underlying model also need to be considered.

  19. Relationship of Human Cumulus Cells and Oocyte during Oocyte Development or Maturation%人卵丘细胞与卵母细胞发育及成熟的关系

    Institute of Scientific and Technical Information of China (English)

    黄鑫; 郝翠芳

    2012-01-01

    卵丘细胞与卵母细胞共处于同一个卵泡液微环境中,卵丘细胞与卵母细胞之间复杂的“对话机制”调控着卵母细胞的成熟和卵丘细胞的增殖延伸.在窦卵泡阶段,卵丘细胞由颗粒细胞分化而来,通过缝隙连接与卵母细胞共同形成一个结构和功能上的合胞体.卵泡发育不同时期,卵丘细胞对卵母细胞的代谢调控主要表现为:在窦卵泡期,卵丘细胞为卵母细胞发育提供必需的营养,而卵母细胞分泌的信号因子亦调控着卵丘细胞的增殖和延伸;在排卵前卵泡中,卵丘细胞主要通过调控卵母细胞中cAMP水平,促使卵母细胞恢复减数分裂;在排卵后卵泡中,卵丘细胞亦影响着精-卵结合及胚胎发育的过程.另外,伴随卵泡内微环境的变化,卵丘细胞与卵母细胞间发生着复杂的信号传递,从而对卵母细胞的发育实现分子水平的调控,其中部分基因可能作为卵母细胞发育成熟、胚胎发育及妊娠结局的分子标志物.%The cumulus cells (CCs) share the same follicular microenvironment with oocyte, and the bidirectional communication between CCs and oocyte is controlling the oocyte maturation and CCs proliferation. CCs originate from granulose cells (GCs) which differentiate into mural GCs and CCs during follicular antrum formation. The signaling between the CCs and oocyte via gap junctions and then they were made up of a structural and functional unit. During the different phases of folliculogenesis, CCs controlled the oocyte development as follows: during the antral phase, CCs provided necessary nourishment to support oocyte development and oocyte secreted signal factors to control the proliferation of CCs; during the pre-ovulatory phase, CCs promoted the oocyte to resume meiosis by controlling the cAMP; during the post-ovulation, the CCs also affected fertilization or embryos development. Furthermore, as the follicular microenvironment was changing, the complex

  20. Cumulus cloud venting of mixed layer ozone

    Science.gov (United States)

    Ching, J. K. S.; Shipley, S. T.; Browell, E. V.; Brewer, D. A.

    1985-01-01

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon.

  1. Cumulus Parameterization: Those Who Can Remember the Past Are Condemned to Repeat It

    CERN Document Server

    Del Genio, Anthony D

    2016-01-01

    Moist convection plays a leading role in the dynamics and energy budget of Earth's tropics and influences the sensitivity of Earth's climate to greenhouse gas increases. Because individual convective cells are much smaller than the gridboxes of 3-dimensional global climate models (GCMs), these models parameterize the effects of an ensemble of moist convective updrafts and downdrafts on the environment. Cumulus parameterization has been a focus of the terrestrial meteorology community for half a century. Only in past decade, however, have GCMs with moist convective physics been applied to other planets. Given our lack of detailed knowledge about convective clouds except on Earth, planetary GCMs are often designed with very simple approaches to cumulus parameterization, adopted from the earliest generations of terrestrial GCMs. These parameterizations were based on breakthroughs in understanding of convection in their time. However, at the same time that planetary GCMs have begun to emerge, a quiet revolution i...

  2. Fast Electronic Solar Cell Tester

    Science.gov (United States)

    Lathrop, J. W.; Saylor, C. R.

    1983-01-01

    Microcomputer controlled system gather current and voltage data. System consists of light source, microcomputer, programable dc power supply, analog/ digital interface, and data storage display equipment. Applies series of test loads to cell via programable dc power supply to obtain I/V characteristic curve and key cell-peformance parameter. Apparatus and programming technique are applicable to devices such as batteries and sensors.

  3. Simulation of solar radiative transfer in cumulus clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.E.; Titov, G.A. [Institute of Atmospheric Optics, Tomsk (Russian Federation)

    1996-04-01

    This work presents a 3-D model of radiative transfer which is used to study the relationship between the spatial distribution of cumulus clouds and fluxes (albedo and transmittance) of visible solar radiation.

  4. Electron Microscopy of Nanostructures in Cells

    DEFF Research Database (Denmark)

    Købler, Carsten

    with cells is therefore increasingly more relevant from both an engineering and a toxicological viewpoint. My work involves developing and exploring electron microscopy (EM) for imaging nanostructures in cells, for the purpose of understanding nanostructure-cell interactions in terms of their possibilities...... in science and concerns in toxicology. In the present work, EM methods for imaging nanostructure-cell interactions have been explored, and the complex interactions documented and ordered. In particular the usability of the focused ion beam scanning electron microscope (FIB-SEM) was explored. Using EM...

  5. Electron Tomography in Plant Cell Biology

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This review focuses on the contribution of electron tomography-based techniques to our understanding of cellular processes in plant cells. Electron microscopy techniques have evolved to provide better three-dimensional resolution and improved preservation of the subcellular components. In particular, the combination of cryofixation/freeze substitution and electron tomography have allowed plant cell biologists to image organelles and macromolecular complexes in their native cellular context with unprecedented three-dimensional resolution (4-7 nm). Until now, electron tomography has been applied in plant cell biology for the study of cytokinesis, Golgi structure and trafficking, formation of plant endosome/prevacuolar compartments, and organization of photosynthetic membranes. We discuss in this review the new insights that these tomographic studies have brought to the plant biology field.

  6. Microphysical imprint of entrainment in warm cumulus

    Directory of Open Access Journals (Sweden)

    Jennifer D. Small

    2013-07-01

    Full Text Available We analyse the cloud microphysical response to entrainment mixing in warm cumulus clouds observed from the CIRPAS Twin Otter during the GoMACCS field campaign near Houston, Texas, in summer 2006. Cloud drop size distributions and cloud liquid water contents from the Artium Flight phase-Doppler interferometer in conjunction with meteorological observations are used to investigate the degree to which inhomogeneous versus homogeneous mixing is preferred as a function of height above cloud base, distance from cloud edge and aerosol concentration. Using four complete days of data with 101 cloud penetrations (minimum 300 m in length, we find that inhomogeneous mixing primarily explains liquid water variability in these clouds. Furthermore, we show that there is a tendency for mixing to be more homogeneous towards the cloud top, which we attribute to the combination of increased turbulent kinetic energy and cloud drop size with altitude which together cause the Damköhler number to increase by a factor of between 10 and 30 from cloud base to cloud top. We also find that cloud edges appear to be air from cloud centres that have been diluted solely through inhomogeneous mixing. Theory predicts the potential for aerosol to affect mixing type via changes in drop size over the range of aerosol concentrations experienced (moderately polluted rural sites to highly polluted urban sites. However, the observations, while consistent with this hypothesis, do not show a statistically significant effect of aerosol on mixing type.

  7. Environmental scanning electron microscopy in cell biology.

    Science.gov (United States)

    McGregor, J E; Staniewicz, L T L; Guthrie Neé Kirk, S E; Donald, A M

    2013-01-01

    Environmental scanning electron microscopy (ESEM) (1) is an imaging technique which allows hydrated, insulating samples to be imaged under an electron beam. The resolution afforded by this technique is higher than conventional optical microscopy but lower than conventional scanning electron microscopy (CSEM). The major advantage of the technique is the minimal sample preparation needed, making ESEM quick to use and the images less susceptible to the artifacts that the extensive sample preparation usually required for CSEM may introduce. Careful manipulation of both the humidity in the microscope chamber and the beam energy are nevertheless essential to prevent dehydration and beam damage artifacts. In some circumstances it is possible to image live cells in the ESEM (2).In the following sections we introduce the fundamental principles of ESEM imaging before presenting imaging protocols for plant epidermis, mammalian cells, and bacteria. In the first two cases samples are imaged using the secondary electron (topographic) signal, whereas a transmission technique is employed to image bacteria.

  8. IMPACTS OF CUMULUS PARAMETERIZATION AND RESOLUTION ON THE MJO SIMULATION

    Institute of Scientific and Technical Information of China (English)

    JIA Xiao-long; LI Chong-yin; LING Jian

    2009-01-01

    Madden-Julian Oscillations (MJO) in six integrations using an AGCM with different cumulus parameterization schemes and resolutions are examined to investigate their impacts on the MJO simulation.Results suggest that the MJO simulation can be affected by both resolution and cumulus parameterization,though the latter,which determines the fundamental ability of the AGCM in simulating the MJO and the characteristics of the simulated MJO,is more crucial than the former. Model resolution can substantially affect the simulated MJO in certain aspects. Increasing resolution cannot improve the simulated MJO substantially,but can significantly modulate the detailed character of the simulated MJO; meanwhile,the impacts of resolution are dependent on the cumulus parameterization,determining the basic features of the MJO. Changes in the resolution do not alter the nature of the simulated MJO but rather regulate the simulation itself,which is constrained by cumulus parameterization schemes. Theretbre,the vertical resolution needs to be increased simultaneously. The vertical profile of diabatic heating may be a crucial factor that is responsible for these different modeling results. To a large extent,it is determined by the cumulus parameterization scheme used.

  9. Advancing Models and Evaluation of Cumulus, Climate and Aerosol Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Gettelman, Andrew [University Corporation for Atmospheric Research (NCAR), Boulder, CO (United States)

    2015-10-27

    This project was successfully able to meet its’ goals, but faced some serious challenges due to personnel issues. Nonetheless, it was largely successful. The Project Objectives were as follows: 1. Develop a unified representation of stratifom and cumulus cloud microphysics for NCAR/DOE global community models. 2. Examine the effects of aerosols on clouds and their impact on precipitation in stratiform and cumulus clouds. We will also explore the effects of clouds and precipitation on aerosols. 3. Test these new formulations using advanced evaluation techniques and observations and release

  10. Semiprognostic tests of the Arakawa-Schubert cumulus parameterization using simulated data

    Science.gov (United States)

    Xu, Kuan-Man; Arakawa, Akio

    1992-01-01

    Semiprognostic tests are performed against data simulated by a cumulus ensemble model to evaluate the Arakawa-Schubert (A-S) cumulus parametrization. It is found that the A-S cumulus parametrization is generally valid despite the existence of mesoscale organization in cumulus convection. The nondiagnostic and nondeterministic aspects of the A-S cumulus parametrization are examined by testing the sensitivity of the parametrization to the horizontal grid resolution. It is also shown that the inclusion of convective-scale downdrafts improves the results of semiprognostic tests.

  11. Levels of cyclic-AMP and cyclic-GMP in porcine oocyte-cumulus complexes and cumulus-free oocytes derived from small and middle follicles during the first 24-hour period of in vitro maturation.

    Science.gov (United States)

    Okudaira, Yuichi; Wakai, Takuya; Funahashi, Hiroaki

    2017-02-23

    The objective of this study was to compare the cAMP and cGMP levels in cumulus-oocyte complexes (COCs) derived from the middle follicles (MFs, 3-6 mm in diameter) and small follicles (SFs, 1-3 mm in diameter) of pre-pubertal gilts during the first 24-h period of maturation in vitro (IVM). Both cAMP and cGMP levels in MF- and SF-derived oocytes did not change during this period. Although the cAMP levels increased in the COCs at 10 and 20 h after the start of IVM, the levels of cAMP were significantly higher in MF-derived COCs than in SF-derived COCs at 20 h after the start of IVM. On the other hand, the cGMP levels in COCs decreased to basal levels between 10 and 20 h after the start of the IVM, whereas cGMP levels were lower in SF-derived COCs than in MF-derived COCs during the first 10 h. The number of cumulus cells was larger in the MF-derived COCs than in the SF-derived COCs during the first 20-h period of IVM. The estimated cAMP level per cumulus cell at 10 h after the start of the IVM was higher in SF-derived COCs than in MF-derived COCs, whereas the estimated cGMP level per cumulus cell was no different between MF- and SF-derived COCs. From these results, we conclude that cAMP and cGMP levels in COCs, but not in oocytes, drastically change during the first 20-h period of IVM, and that both cAMP and cGMP levels significantly differ between MF- and SF-derived COCs.

  12. Fluctuations in a quasi-stationary shallow cumulus cloud ensemble

    Directory of Open Access Journals (Sweden)

    M. Sakradzija

    2014-08-01

    Full Text Available We propose an approach to stochastic parameterization of shallow cumulus clouds to represent the convective variability and its dependence on the model resolution. To collect the information about the individual cloud lifecycles and the cloud ensemble as a whole, we employ a Large-Eddy Simulation model (LES and a cloud tracking algorithm, followed by conditional sampling of clouds at the cloud-base level. In the case of a shallow cumulus ensemble, the cloud-base mass flux distribution is bimodal due to the different shallow cloud subtypes. Each distribution mode can be approximated with a Weibull distribution, explaining the deviation from a single-parameter exponential shape through the diversity in cloud lifecycles. The exponential distribution of cloud mass flux previously suggested for deep convection parameterization is a special case of the Weibull distribution, which opens a way towards unification of the statistical convective ensemble formalism of shallow and deep cumulus clouds. Based on the empirical and theoretical findings, a stochastic model has been developed to simulate a shallow convective cloud ensemble. It is formulated as a compound random process, with the number of convective elements drawn from a Poisson distribution, and the cloud mass flux sampled from a mixed Weibull distribution. Convective memory is accounted for through the explicit cloud lifecycles, making the model formulation consistent with the choice of the Weibull cloud mass flux distribution function. The memory of individual shallow clouds is required to capture the correct convective variability. The resulting distribution of the subgrid convective states in the considered shallow cumulus case is scale-adaptive – the smaller the grid size, the broader the distribution.

  13. Fluctuations in a quasi-stationary shallow cumulus cloud ensemble

    Directory of Open Access Journals (Sweden)

    M. Sakradzija

    2015-01-01

    Full Text Available We propose an approach to stochastic parameterisation of shallow cumulus clouds to represent the convective variability and its dependence on the model resolution. To collect information about the individual cloud lifecycles and the cloud ensemble as a whole, we employ a large eddy simulation (LES model and a cloud tracking algorithm, followed by conditional sampling of clouds at the cloud-base level. In the case of a shallow cumulus ensemble, the cloud-base mass flux distribution is bimodal, due to the different shallow cloud subtypes, active and passive clouds. Each distribution mode can be approximated using a Weibull distribution, which is a generalisation of exponential distribution by accounting for the change in distribution shape due to the diversity of cloud lifecycles. The exponential distribution of cloud mass flux previously suggested for deep convection parameterisation is a special case of the Weibull distribution, which opens a way towards unification of the statistical convective ensemble formalism of shallow and deep cumulus clouds. Based on the empirical and theoretical findings, a stochastic model has been developed to simulate a shallow convective cloud ensemble. It is formulated as a compound random process, with the number of convective elements drawn from a Poisson distribution, and the cloud mass flux sampled from a mixed Weibull distribution. Convective memory is accounted for through the explicit cloud lifecycles, making the model formulation consistent with the choice of the Weibull cloud mass flux distribution function. The memory of individual shallow clouds is required to capture the correct convective variability. The resulting distribution of the subgrid convective states in the considered shallow cumulus case is scale-adaptive – the smaller the grid size, the broader the distribution.

  14. Metabolic differences in bovine cumulus-oocyte complexes matured in vitro in the presence or absence of follicle-stimulating hormone and bone morphogenetic protein 15.

    Science.gov (United States)

    Sutton-McDowall, Melanie L; Mottershead, David G; Gardner, David K; Gilchrist, Robert B; Thompson, Jeremy G

    2012-10-01

    Bidirectional communication between cumulus cells and the oocyte is necessary to achieve oocyte developmental competence. The aim of the present study was to examine the effects of recombinant human bone morphogenetic protein 15 (rhBMP15) and follicle-stimulating hormone (FSH) supplementation on bovine cumulus-oocyte complex (COC) metabolism during maturation. Bovine COCs were matured in the presence of absence of FSH, rhBMP15, or both for 23 h. The addition of FSH and rhBMP15 increased blastocyst development (without rhBMP15 and FSH, 28.4% ± 7.4%; with FSH and rhBMP15, 51.5% ± 5.4%; P levels. rhBMP15 supplementation (regardless of FSH) significantly decreased ADP levels in COCs, leading to an increase in ATP:ADP ratios (P Indicators of mitochondrial activity and cellular REDOX, oxidized flavin adenine dinucleotide (FAD(++)) and reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H), levels within the oocyte of COCs were significantly higher with rhBMP15 alone, whereas the presence of FSH diminished the rhBMP15 effect. Regardless of treatment, no changes in REDOX state (FAD(++):NAD(P)H). The significant increase in FAD(++) and NAD(P)H in COCs with rhBMP15 was mediated via cumulus cells, because no differences were found in denuded oocytes cultured in the presence or absence of FSH, rhBMP15, or both. The present study demonstrates that a principal metabolic consequence of FSH supplementation of COCs is to alter the glycolytic rate of cumulus cells, whereas that of rhBMP15 is to regulate oxidative phosphorylation in the oocyte, even though it acts via cumulus cells. These effects are tempered when FSH and rhBMP15 are present together but, nonetheless, yield the best oocyte developmental competence.

  15. Influence of co-culture with denuded oocytes during in vitro maturation on fertilization and developmental competence of cumulus-enclosed porcine oocytes in a defined system.

    Science.gov (United States)

    Appeltant, Ruth; Somfai, Tamás; Kikuchi, Kazuhiro; Maes, Dominiek; Van Soom, Ann

    2016-04-01

    Co-culture of cumulus-oocyte complexes (COCs) with denuded oocytes (DOs) during in vitro maturation (IVM) was reported to improve the developmental competence of oocytes via oocyte-secreted factors in cattle. The aim of the present study was to investigate if addition of DOs during IVM can improve in vitro fertilization (IVF) and in vitro culture (IVC) results for oocytes in a defined in vitro production system in pigs. The maturation medium was porcine oocyte medium supplemented with gonadotropins, dbcAMP and β-mercaptoethanol. Cumulus-oocyte complexes were matured without DOs or with DOs in different ratios (9 COC, 9 COC+16 DO and 9 COC+36 DO). Consequently; oocytes were subjected to IVF as intact COCs or after denudation to examine if DO addition during IVM would affect cumulus or oocyte properties. After fertilization, penetration and normal fertilization rates of zygotes were not different between all tested groups irrespective of denudation before IVF. When zygotes were cultured for 6 days, no difference could be observed between all treatment groups in cleavage rate, blastocyst rate and cell number per blastocyst. In conclusion, irrespective of the ratio, co-culture with DOs during IVM did not improve fertilization parameters and embryo development of cumulus-enclosed porcine oocytes in a defined system.

  16. Relationship of telomere length in cumulus cells with oocytes maturation and outcome of IVF-ET in patients with different ages%不同年龄IVF-ET患者卵丘颗粒细胞端粒长度与卵母细胞成熟度及妊娠结局的关系

    Institute of Scientific and Technical Information of China (English)

    王兴玲; 蔡鹏飞; 张文娟; 肖雅琳

    2016-01-01

    目的:探讨体外受精-胚胎移植( IVF-ET)卵丘颗粒细胞的端粒长度与卵母细胞成熟度及妊娠结局的关系。方法:收集81例行体外受精-胚胎移植患者的卵丘颗粒细胞,根据患者的年龄,分为低龄(<35岁)组42例和高龄(≥35岁)组39例。应用qRT-PCR测量卵丘颗粒细胞端粒长度。结果:卵丘颗粒细胞端粒长度与年龄呈负相关(r=-0.267,P=0.021),低、高龄组内成熟卵母细胞的卵丘颗粒细胞端粒长度明显比未成熟卵母细胞的长(P<0.05)。高龄组妊娠者端粒长度较未妊娠者长(P<0.05)。结论:在IVF-ET中,卵丘颗粒细胞的相对端粒长度随年龄增长逐渐缩短,可反映卵母细胞的成熟度;端粒长度缩短可能会影响妊娠结局。%Aim:To investigate the relationship of the relative telomere length in cumulus cells (CCs) with oocytes at different mature stages and the outcome of in vitro fertilization and embryo transfer (IVF-ET).Methods:Oocyte-cumulus complex samples were collected from 81 patients undergoing IVF-ET and CCs were manually separated .A total of 42 women (<35 years,the younger group) and 39 women(≥35 years, the older group) were collected.The oocyte maturation and the result of clinical pregnancy were recorded in different groups .DNA was extracted from CCs and assessed for telomere length by real-time quantitative PCR .Results: There were negative correlation between relative telomere length of CCs with the patients′age (r=-0.267, P=0.021).The relative telomere length of CCs was higher in mature oocytes than immature oocytes in both groups (P<0.05).There was a significantly higher telomere length of CCs in the pregnant sub-group than in the non-pregnant subgroup among the older group (P<0.05).Conclusion:In IVF-ET, the relative telomere length of CCs gradually shortened with age .The telomere length of CCs could reflect the degree of oocyte maturation and may be

  17. Shallow Cumulus Variability at the ARM Eastern North Atlantic Site

    Science.gov (United States)

    Lamer, K.; Kollias, P.; Ghate, V. P.; Luke, E. P.

    2016-12-01

    Cumulus clouds play a critical role in modulating the radiative and hydrological budget of the lower troposphere. These clouds, which are ubiquitous in regions of large-scale subsidence over the oceans, tend to be misrepresented in global climate models. Island-based, long-term, high-resolution ground-based observations can provide valuable insights on the factors controlling their macroscopic and microphysical properties and subsequenlty assist in model evaluation and guidance. Previous studies, limited to fair-weather cumuli over land, revealed that their fractional coverage is only weakly correlated with several parameters; the best ones being complex dynamical characteristics of the subcloud layer (vertical velocity skewness and eddy coherence). Other studies noted a relationship between cumuli depth and their propensity to precipitate. The current study will expand on such analysis by performing detail characterization of the full spectrum of shallow cumulus fields from non-precipitating to precipitating in the context of the large-scale forcing (i.e. thermodynamic structure and subsidence rates). Two years of ground-based remote sensing observations collected at the Atmospheric Radiation Measurement (ARM) Eastern North Atlantic (ENA) site are used to document macroscopic (cloud depth, cord length, cover), microphysical (liquid water path, cloud base rain rate) and dynamical (cloud base mass flux, eddy dissipation rate) cumuli properties. The observed variability in shallow cumulus is examined in relation to the variability of the large-scale environment as captured by the humidity profile, the magnitude of the low-level horizontal winds and near-surface aerosol conditions.

  18. Solar electron source and thermionic solar cell

    Directory of Open Access Journals (Sweden)

    Parham Yaghoobi

    2012-12-01

    Full Text Available Common solar technologies are either photovoltaic/thermophotovoltaic, or use indirect methods of electricity generation such as boiling water for a steam turbine. Thermionic energy conversion based on the emission of electrons from a hot cathode into vacuum and their collection by an anode is also a promising route. However, thermionic solar conversion is extremely challenging as the sunlight intensity is too low for heating a conventional cathode to thermionic emission temperatures in a practical manner. Therefore, compared to other technologies, little has been done in this area, and the devices have been mainly limited to large experimental apparatus investigated for space power applications. Based on a recently observed “Heat Trap” effect in carbon nanotube arrays, allowing their efficient heating with low-power light, we report the first compact thermionic solar cell. Even using a simple off-the-shelf focusing lens, the device delivered over 1 V across a load. The device also shows intrinsic storage capacity.

  19. Sensitivity of the Simulated Tropical Intraseasonal Oscillation to Cumulus Parameterizations

    Institute of Scientific and Technical Information of China (English)

    JIA Xiaolong; LI Chongyin

    2008-01-01

    The sensitivity of the simulated tropical intraseasonal oscillation or MJO (Madden and Julian oscilla tion)to different cumulus parameterizations is studied by using an atmospheric general circulation model (GCM)-SAMIL(Spectral Atmospheric Model of IAP LASG).Results show that performance of the model in simulating the MJO alters widely when using two different cumulus parameterization schemes-the moist convective adjustment scheme(MCA)and the Zhang-McFarlane(ZM)scheme.MJO simulated by the MCA scheme was found to be more realistic than that simulated by the ZM scheme.MJO produced by the ZM scheme is too weak and shows little propagation characteristics.Weak moisture convergence at low levels simulated by the ZM scheme is not enough to maintain the structure and the eastward propagation of the oscillation.These two cumulus schemes produced different vertical structures of the heating profile.The heating profile produced by the ZM scheme is nearly uniform with height and the heating is too weak compared to that produced by the MCA,which maybe contributes greatly to the failure of simulating a reasonable MJO.Comparing the simulated MJO by these two schemes indicate that the MJO simulated by the GCM is highly sensitive to cumulus parameterizations implanted in.The diabatic heating profile plays an important role in the performance of the GCM.Three sensitivity experiments with different heating profiles are designed in which modified heating profiles peak respectively in the upper troposphere(UH), middle troposphere(MH),and lower troposphere(LH).Both the LH run and the MH run produce eastward propagating signals on the intraseasonal timescale,while it is interesting that the intraseasonal timescale signals produced by the UH run propagate westward.It indicates that a realistic intraseasonal oscillation is more prone to be excited when the maximum heating concentrates in the middle-low levels,especially in the middle levels,while westward propagating disturbances axe more

  20. Sensitivity of land surface and Cumulus schemes for Thunderstorm prediction

    Science.gov (United States)

    Kumar, Dinesh; Mohanty, U. C.; Kumar, Krishan

    2016-06-01

    The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL). How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme) and WSM-6 (Cumulus Scheme) have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6, and KF schemes

  1. Vastaanottovirkailijan ergonomian tutkimus ja kehitys: Cumulus Hotel Lappeenranta

    OpenAIRE

    Kokkonen, Teemu

    2017-01-01

    Opinnäytetyön tavoitteena oli tutkia ja löytää hyviä ergonomiaratkaisuja Cumulus Hotel Lappeenrannan vastaanottoon ennen syksyllä 2017 alkavaa remonttia. Ergonomia tarkoittaa ihmisen ja työn yhteensovittamista. Sen tehtävä on tutkia ihmisen ja tekniikan sekä ympäristön vuorovaikutusta ja saada aikaan ihmiselle mieluisa ja toimiva toimintaympäristö työntekoa varten. Teoriaosuudessa käsitellään ergonomiaa käsitteenä ja avataan sen alalajeja fyysistä sekä kognitiivista ergonomiaa. Lisäksi e...

  2. Sensitivity of land surface and Cumulus schemes for Thunderstorm prediction

    Directory of Open Access Journals (Sweden)

    D. Kumar

    2016-06-01

    Full Text Available The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL. How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme and WSM-6 (Cumulus Scheme have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6

  3. Interaction of a cumulus cloud ensemble with the large-scale environment. III - Semi-prognostic test of the Arakawa-Schubert cumulus parameterization

    Science.gov (United States)

    Lord, S. J.

    1982-01-01

    The verification of the Arakawa and Schubert (1974) cumulus parameterization is continued using a semiprognostic approach. Observed data from Phase III of GATE are used to provide estimates of the large-scale forcing of a cumulus ensemble at each observation time. Instantaneous values of the precipitation and the warming and drying due to cumulus convection are calculated using the parameterization. The results show that the calculated precipitation agrees very well with estimates from the observed large-scale moisture budget and from radar observations. The calculated vertical profiles of cumulus warming and drying also are quite similar to the observed. It is shown that the closure assumption adopted in the parameterization (the cloud-work function quasi-equilibrium) results in errors of generally less than 10% in the calculated precipitation. The sensitivity of the parameterization to some assumptions of the cloud ensemble model and the solution method for the cloud-base mass flux is investigated.

  4. Abortive expansion of the cumulus and impaired fertility in mice lacking the prostaglandin E receptor subtype EP2

    OpenAIRE

    Hizaki, Hiroko; Segi, Eri; Sugimoto, Yukihiko; Hirose, Masaya; Saji, Tomomi; Ushikubi, Fumitaka; Matsuoka, Toshiyuki; Noda, Yoichi; Tanaka, Takashi; Yoshida, Nobuaki; Narumiya, Shuh; Ichikawa, Atsushi

    1999-01-01

    Female mice lacking the gene encoding the prostaglandin (PG) E2 receptor subtype EP2 (EP2−/−) become pregnant and deliver their pups at term, but with a much reduced litter size. A decrease in ovulation number and a much reduced fertilization rate were observed in EP2−/− females without difference of the uterus to support implantation of wild-type embryos. Treatment with gonadotropins induced EP2 mRNA expression in the cumulus cells of ovarian follicles of wild-type mice. The immature cumuli ...

  5. Low impact to fixed cell processing aiming transmission electron microscopy

    Science.gov (United States)

    Barth, Ortrud Monika; da Silva, Marcos Alexandre Nunes; Barreto-Vieira, Debora Ferreira

    2016-01-01

    In cell culture, cell structures suffer strong impact due to centrifugation during processing for electron microscope observation. In order to minimise this effect, a new protocol was successfully developed. Using conventional reagents and equipments, it took over one week, but cell compression was reduced to none or the lowest deformation possible. PMID:27276186

  6. Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix.

    Science.gov (United States)

    Briggs, David C; Birchenough, Holly L; Ali, Tariq; Rugg, Marilyn S; Waltho, Jon P; Ievoli, Elena; Jowitt, Thomas A; Enghild, Jan J; Richter, Ralf P; Salustri, Antonietta; Milner, Caroline M; Day, Anthony J

    2015-11-27

    The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix.

  7. Structure of a bacterial cell surface decaheme electron conduit.

    Science.gov (United States)

    Clarke, Thomas A; Edwards, Marcus J; Gates, Andrew J; Hall, Andrea; White, Gaye F; Bradley, Justin; Reardon, Catherine L; Shi, Liang; Beliaev, Alexander S; Marshall, Matthew J; Wang, Zheming; Watmough, Nicholas J; Fredrickson, James K; Zachara, John M; Butt, Julea N; Richardson, David J

    2011-06-07

    Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along "nanowire" appendages. We present a 3.2-Å crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65-Å octaheme chain transects the length of the protein and is bisected by a planar 45-Å tetraheme chain that connects two extended Greek key split β-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g., minerals), soluble substrates (e.g., flavins), and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface.

  8. Solar cell evaluation using electron beam induced current with the large chamber scanning electron microscope

    Science.gov (United States)

    Wink, Tara; Kintzel, Edward; Marienhoff, Peter; Klein, Martin

    2012-02-01

    An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanning electron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanning electron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

  9. Observations of sulfur dioxide uptake and new particle formation in a midlatitude cumulus cloud

    OpenAIRE

    Peter, J. R.; S. T. Siems; Jensen, J.B.; Gras, J. L.; Ishizaka, Y.; Hacker, J. M.

    2006-01-01

    International audience; Airborne measurements, obtained during the Asian Aerosol Characterisation Experiment (ACE-Asia), of SO2 and condensation nuclei (CN) concentrations were made in the local environment of a cumulus cloud band. Conserved quantities, wet equivalent potential temperature ?q, and total water content Q, were used to identify the sources of air detrained on the downwind side of the cumulus band. It was found that ~65% of the detrained air originated from below cloud base and t...

  10. A Cloud-resolving Study on the Role of Cumulus Merger in MCS with Heavy Precipitation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The cumulus merging processes in generating the mesoscale convective system (MCS) on 23 August 2001 in the Beijing region are studied by using a cloud-resolving mesoscale model of MM5. The results suggest that the merger processes occurred among isolated convective cells formed in high mountain region during southerly moving process play critical role in forming MCS and severe precipitating weather events such as hailfall, heavy rain, downburst and high-frequency lightning in the region. The formation of the MCS experiences multi-scale merging processes from single-cell scale merging to cloud cluster-scale merging, and high core merging. The merger process can apparently alter cloud dynamical and microphysical properties through enhancing both low- and middle-level forcing. Also, lightning flash rates are enhanced by the production of more intense and deeper convective cells by the merger process, especially by which, the more graupel-like ice particles are formed in clouds. The explosive convective development and the late peak lightning flash rate can be found during merging process.

  11. An Overview of Electron Acceptors in Microbial Fuel Cells.

    Science.gov (United States)

    Ucar, Deniz; Zhang, Yifeng; Angelidaki, Irini

    2017-01-01

    Microbial fuel cells (MFC) have recently received increasing attention due to their promising potential in sustainable wastewater treatment and contaminant removal. In general, contaminants can be removed either as an electron donor via microbial catalyzed oxidization at the anode or removed at the cathode as electron acceptors through reduction. Some contaminants can also function as electron mediators at the anode or cathode. While previous studies have done a thorough assessment of electron donors, cathodic electron acceptors and mediators have not been as well described. Oxygen is widely used as an electron acceptor due to its high oxidation potential and ready availability. Recent studies, however, have begun to assess the use of different electron acceptors because of the (1) diversity of redox potential, (2) needs of alternative and more efficient cathode reaction, and (3) expanding of MFC based technologies in different areas. The aim of this review was to evaluate the performance and applicability of various electron acceptors and mediators used in MFCs. This review also evaluated the corresponding performance, advantages and disadvantages, and future potential applications of select electron acceptors (e.g., nitrate, iron, copper, perchlorate) and mediators.

  12. Particle-in-cell Simulations with Kinetic Electrons

    Energy Technology Data Exchange (ETDEWEB)

    J.L.V. Lewandowski

    2004-02-12

    A new scheme, based on an exact separation between adiabatic and nonadiabatic electron responses, for particle-in-cell (PIC) simulations of drift-type modes is presented. The (linear and nonlinear) elliptic equations for the scalar fields are solved using a multi-grid solver. The new scheme yields linear growth rates in excellent agreement with theory and it is shown to conserve energy well into the nonlinear regime. It is also demonstrated that simulations with few electrons are reliable and accurate, suggesting that large-scale, PIC simulations with electron dynamics in toroidal geometry (e.g., tokamaks and stellarators plasmas) are within reach of present-day massively parallel supercomputers.

  13. Aerosol Impacts on the Growth of Cumulus Congestus Clouds

    Science.gov (United States)

    Sheffield, A. M.; van den Heever, S. C.; Saleeby, S. M.

    2012-12-01

    Tropical convection has been observed to contain three modes of convection, the middle mode of which is cumulus congestus clouds. This study investigates the impacts of aerosol, specifically those aerosols that can serve as cloud condensation nuclei, on the growth and development of congestus clouds observed within idealized cloud-resolving model (CRM) simulations conducted under a state of radiative-convective equilibrium (RCE). The model employed here is the Regional Atmospheric Modeling System (RAMS). RAMS CRM simulations were completed using a large two-dimensional domain (7200 km) at fine resolution (1 km) and long duration (100 days). Results indicate that congestus in more polluted conditions extend to greater heights more frequently than those developing in clean cases. Greater cloud water mass and ice mass forms in more polluted conditions, though ice forms at a fraction of the rate of the cloud mass. The importance of vapor diffusional growth of cloud droplets in the more polluted conditions is highlighted as one such process contributing to congestus development through latent heat release.

  14. Organic photovoltaic cells based on unconventional electron donor fullerene and electron acceptor copper hexadecafluorophthalocyanine

    Science.gov (United States)

    Yang, J. L.; Sullivan, P.; Schumann, S.; Hancox, I.; Jones, T. S.

    2012-01-01

    We demonstrate organic discrete heterojunction photovoltaic cells based on fullerene (C60) and copper hexadecafluorophthalocyanine (F16CuPc), in which the C60 and F16CuPc act as the electron donor and the electron acceptor, respectively. The C60/F16CuPc cells fabricated with conventional and inverted architectures both exhibit comparable power conversion efficiencies. Furthermore, we show that the photocurrent in both cells is generated by a conventional exciton dissociation mechanism rather than the exciton recombination mechanism recently proposed for a similar C60/F16ZnPc system [Song et al., J. Am. Chem. Soc. 132, 4554 (2010)]. These results demonstrate that new unconventional material systems are a potential way to fabricate organic photovoltaic cells with inverted as well as conventional architectures.

  15. Electron Acceptor Materials Engineering in Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Liu, Huan

    2011-07-15

    Lead sulfide colloidal quantum dot (CQD) solar cells with a solar power conversion efficiency of 5.6% are reported. The result is achieved through careful optimization of the titanium dioxide electrode that serves as the electron acceptor. Metal-ion-doped sol-gel-derived titanium dioxide electrodes produce a tunable-bandedge, well-passivated materials platform for CQD solar cell optimization. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Electron microscopy in cell biology: integrating structure and function

    NARCIS (Netherlands)

    Koster, A.J.; Klumperman, J.

    2003-01-01

    Electron microscopy (EM) is at the highest-resolution limit of a spectrum of complementary morphological techniques. When combined with molecular detection methods, EM is the only technique with sufficient resolution to localize proteins to small membrane subdomains in the context of the cell. Recen

  17. Hydrogen peroxide inhibits photosynthetic electron transport in cells of cyanobacteria.

    Science.gov (United States)

    Samuilov, V D; Bezryadnov, D B; Gusev, M V; Kitashov, A V; Fedorenko, T A

    2001-06-01

    The effect of H2O2 on photosynthetic O2 evolution and photosynthetic electron transfer in cells of cyanobacteria Anabaena variabilis and Anacystis nidulans was studied. The following experiments were performed: 1) directly testing the effect of exogenous H2O2; 2) testing the effect of intracellular H2O2 generated with the use of methyl viologen (MV); 3) testing the effect of inhibiting intracellular H2O2 decomposition by salicylic acid (SA) and 3-amino-1,2,4-triazole (AT). H2O2 inhibited photosynthetic O2 evolution and light-induced reduction of p-benzoquinone (BQ) + ferricyanide (FeCy) in the Hill reaction. The I50 value for H2O2 was ~0.75 mM. Photosynthetic electron transfer in the cells treated with H2O2 was not maintained by H2O2, NH2OH, 1,5-diphenylcarbazide, tetraphenylboron, or butylated hydroxytoluene added as artificial electron donors for Photosystem (PS) II. The H2O --> CO2, H2O --> MV (involving PSII and PSI) and H2O --> BQ + FeCy (chiefly dependent on PSII) electron transfer reactions were inhibited upon incubation of the cells with MV, SA, or AT. The N,N,N,N-tetramethyl-p-phenylenediamine --> MV (chiefly dependent on PSI) electron transfer was inhibited by SA and AT but was resistant to MV. The results show that H2O2 inhibits photosynthetic electron transfer. It is unlikely that H2O2 could be a physiological electron donor in oxygenic photosynthesis.

  18. Effect of oil overlay on inhibition potential of roscovitine in sheep cumulus-oocyte complexes.

    Science.gov (United States)

    Crocomo, L F; Marques Filho, W C; Ulian, C M V; Branchini, N S; Silva, D T; Ackermann, C L; Landim-Alvarenga, F C; Bicudo, S D

    2015-06-01

    Inhibitors of cyclin-dependent kinases, as roscovitine, have been used to prevent the spontaneous resumption of meiosis in vitro and to improve the oocyte developmental competence. In this study, the interference of oil overlay on the reversible arrest capacity of roscovitine in sheep oocytes as well as its effects on cumulus expansion was evaluated. For this, cumulus-oocyte complexes (COCs) were cultured for 20 h in TCM 199 with 10% foetal bovine serum (Control) containing 75 μm roscovitine (Rosco). Subsequently, they were in vitro matured (IVM) for further 18 h in inhibitor-free medium with LH and FSH. The culture was performed in Petri dishes under mineral oil (+) or in 96 well plates without oil overlay (-) at 38.5°C and 5% CO2 . At 20 and 38 h, the cumulus expansion and nuclear maturation were evaluated under stereomicroscope and by Hoechst 33342 staining, respectively. No group presented cumulus expansion at 20 h. After additional culture with gonadotrophins, a significant rate of COCs from both Control groups (+/-) exhibited total expansion while in both Rosco groups (+/-) the partial expansion prevailed. Among the oocytes treated with roscovitine, 65.2% were kept at GV in the absence of oil overlay while 40.6% of them reached MII under oil cover (p roscovitine without affecting the cumulus expansion rate or the subsequent meiosis progression. © 2015 Blackwell Verlag GmbH.

  19. Analysis of cumulus solar irradiance reflectance (CSIR) events

    Science.gov (United States)

    Laird, John L.; Harshvardhan

    Clouds are extremely important with regard to the transfer of solar radiation at Earth's surface. This study investigates Cumulus Solar Irradiance Reflection (CSIR) using ground-based pyranometers. CSIR events are short-term increases in solar radiation observed at the surface as a result of reflection off the sides of convective clouds. When Sun-cloud observer geometry is favorable, these occurrences produce characteristic spikes in the pyranometer traces and solar irradiance values may exceed expected clear-sky values. Ultraviolet CSIR events were investigated during the summer of 1995 using UVA and UVB pyranometers. Observed data were compared to clear-sky curves which were generated using a third degree polynomial best-fit line technique. Periods during which the observed data exceeded this clear-sky curve were identified as CSIR events. The magnitude of a CSIR event was determined by two different quantitative calculations. The MAC (magnitude above clear-sky) is an absolute measure of the difference between the observed and clear-sky irradiances. Maximum MAC values of 3.4 Win -2 and 0.0169 Wm -2 were observed at the UV-A and UV-B wavelengths, respectively. The second calculation determined the percentage above clear-sky (PAC) which indicated the relative magnitude of a CSIR event. Maximum UV-A and UV-B PAC magnitudes of 10.1% and 7.8%, respectively, were observed during the study. Also of interest was the duration of the CSIR events which is a function of Sun-cloud-sensor geometry and the speed of cloud propagation over the measuring site. In both the UV-A and UV-B wavelengths, significant CSIR durations of up to 30 minutes were observed. C 1997 Elsevier Science B.V.

  20. Optical and electronic loss analysis of mesoporous solar cells

    Science.gov (United States)

    Kovalsky, Anton; Burda, Clemens

    2016-07-01

    We review the art of complete optical and electronic characterization of the popular mesoporous solar cell motif. An overview is given of how the mesoporous paradigm is applied to solar cell technology, followed by a discussion on the variety of techniques available for thoroughly probing efficiency leaching mechanisms at every stage of the energy transfer pathway. Some attention is dedicated to the rising importance of computational results to augment loss analysis due to the complexity of solar cell devices, which have emergent properties that are important to account for, but difficult to measure, such as parasitic absorption.

  1. Ultrasonographic-guided retrieval of cumulus oocyte complexes after super-stimulation in dromedary camel (Camelus dromedarius).

    Science.gov (United States)

    Wani, N A; Skidmore, J A

    2010-08-01

    In Experiment 1, studies were conducted to apply the transvaginal ultrasound guided ovum pick-up (OPU) technique in dromedary camels after their ovarian super-stimulation and in vivo oocyte maturation. In Experiment 2, the developmental potential of two commonly used oocyte types, i.e., in vivo matured oocytes collected by OPU and abattoir derived in vitro-matured oocytes was compared after their chemical activation. In Experiment 3, developmental competence of oocytes collected from super-stimulated camels by OPU, matured either in vivo or in vitro, was compared after their chemical activation. Mature female dromedary camels super-stimulated with a combination of eCG and pFSH were given an injection of 20 microg of the GnRH analogue, buserelin 24, 26, or 28 h before the scheduled OPU. For collection of cumulus oocyte complexes (COCs) the transducer was guided through the vulva into the cranial most portion of the vagina and 17-gauge, 55 cm single-lumen needle was placed in the needle guide of the ultrasound probe and advanced through the vaginal fornix and into the follicle. Follicular fluid was aspirated using a regulated vacuum pump into tubes containing embryo-flushing media. Aspirates were searched for COCs using a stereomicroscope, and they were then denuded of cumulus cells by hyaluronidase and repeated pipetting. The oocytes were classified as mature (with a visible polar body), immature (with no visible polar body), activated (with divided or fragmented ooplasm) and others (degenerated and abnormal). Overall an average of 12.12 +/- 7.9 COCs were aspirated per animal with an oocyte recovery rate from the aspirated follicles of about 77%. The majority (> 90%) of the collected COCs by OPU were with loose and expanded cumulus cells. The proportion of matured oocytes obtained at 28-29 h (91.2 +/- 4.1) and 26-27 h (82.1 +/- 3.4) were higher (P dromedary camels 26-28 h after GnRH administration. The developmental response, to chemical activation, of in vivo

  2. Electron tomography of HEK293T cells using scanning electron microscope-based scanning transmission electron microscopy.

    Science.gov (United States)

    You, Yun-Wen; Chang, Hsun-Yun; Liao, Hua-Yang; Kao, Wei-Lun; Yen, Guo-Ji; Chang, Chi-Jen; Tsai, Meng-Hung; Shyue, Jing-Jong

    2012-10-01

    Based on a scanning electron microscope operated at 30 kV with a homemade specimen holder and a multiangle solid-state detector behind the sample, low-kV scanning transmission electron microscopy (STEM) is presented with subsequent electron tomography for three-dimensional (3D) volume structure. Because of the low acceleration voltage, the stronger electron-atom scattering leads to a stronger contrast in the resulting image than standard TEM, especially for light elements. Furthermore, the low-kV STEM yields less radiation damage to the specimen, hence the structure can be preserved. In this work, two-dimensional STEM images of a 1-μm-thick cell section with projection angles between ±50° were collected, and the 3D volume structure was reconstructed using the simultaneous iterative reconstructive technique algorithm with the TomoJ plugin for ImageJ, which are both public domain software. Furthermore, the cross-sectional structure was obtained with the Volume Viewer plugin in ImageJ. Although the tilting angle is constrained and limits the resulting structural resolution, slicing the reconstructed volume generated the depth profile of the thick specimen with sufficient resolution to examine cellular uptake of Au nanoparticles, and the final position of these nanoparticles inside the cell was imaged.

  3. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy

    Science.gov (United States)

    Lerner, Thomas R.; Burden, Jemima J.; Nkwe, David O.; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L.; Peddie, Christopher J.; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G.

    2017-01-01

    ABSTRACT The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. PMID:27445312

  4. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy.

    Science.gov (United States)

    Russell, Matthew R G; Lerner, Thomas R; Burden, Jemima J; Nkwe, David O; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L; Peddie, Christopher J; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G; Collinson, Lucy M

    2017-01-01

    The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. © 2017. Published by The Company of Biologists Ltd.

  5. Probing Battery Chemistry with Liquid Cell Electron Energy Loss Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Aguiar, Jeffery A.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren L.

    2015-11-25

    We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn2O4 and Li4Ti5O12 battery electrodes within a battery solvent. The use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. Furthermore, we discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.

  6. Contributions to the implementation of the Arakawa-Schubert cumulus parameterization in the GLA GCM

    Science.gov (United States)

    Sud, Y. C.; Chao, Winston C.; Walker, G. K.

    1991-01-01

    The roles of the Critical Cloud Work Function (CCWF) data set and the upper and lower bounds on entrainment by cumulus plumes in the Arakawa-Schubert cumulus parameterization (ASCP) in the GLA GCM (Geller et al., 1988) were investigated in two sets of experiments. It was found that the horizontal and vertical distribution of cumulus heating can be altered in ASCP by adjusting these parameters. These changes can have a strong influence on the vertical structure of condensation heating, water vapor distribution, temperature, and rainfall. The CCWF is an important limiting parameter that controls the onset of different cloud types; increasing the threshold values of CCWF for all clouds tends to concentrate the rainfall into a narrower ITCZ and affects the rainfall during the initial adjustment period.

  7. Fullerene derivatives as electron acceptors for organic photovoltaic cells.

    Science.gov (United States)

    Mi, Dongbo; Kim, Ji-Hoon; Kim, Hee Un; Xu, Fei; Hwang, Do-Hoon

    2014-02-01

    Energy is currently one of the most important problems humankind faces. Depletion of traditional energy sources such as coal and oil results in the need to develop new ways to create, transport, and store electricity. In this regard, the sun, which can be considered as a giant nuclear fusion reactor, represents the most powerful source of energy available in our solar system. For photovoltaic cells to gain widespread acceptance as a source of clean and renewable energy, the cost per watt of solar energy must be decreased. Organic photovoltaic cells, developed in the past two decades, have potential as alternatives to traditional inorganic semiconductor photovoltaic cells, which suffer from high environmental pollution and energy consumption during production. Organic photovoltaic cells are composed of a blended film of a conjugated-polymer donor and a soluble fullerene-derivative acceptor sandwiched between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-coated indium tin oxide positive electrode and a low-work-function metal negative electrode. Considerable research efforts aim at designing and synthesizing novel fullerene derivatives as electron acceptors with up-raised lowest unoccupied molecular orbital energy, better light-harvesting properties, higher electron mobility, and better miscibility with the polymer donor for improving the power conversion efficiency of the organic photovoltaic cells. In this paper, we systematically review novel fullerene acceptors synthesized through chemical modification for enhancing the photovoltaic performance by increasing open-circuit voltage, short-circuit current, and fill factor, which determine the performance of organic photovoltaic cells.

  8. Cell filling in gravure printing for printed electronics.

    Science.gov (United States)

    Cen, Jialiang; Kitsomboonloha, Rungrot; Subramanian, Vivek

    2014-11-18

    Highly scaled direct gravure is a promising printing technique for printed electronics due to its large throughput, high resolution, and simplicity. Gravure can print features in the single micron range at printing speeds of ∼1 m/s by using an optimized cell geometry and optimized printing conditions. The filling of the cells on the gravure cylinder is a critical process, since the amount of ink in the cells strongly impacts printed feature size and quality. Therefore, an understanding of cell filling is crucial to make highly scaled gravure printed electronics viable. In this work we report a novel experimental setup to investigate the filling process in real time, coupled with numerical simulations to gain insight into the experimental observations. By varying viscosity and filling speed, we ensure that the dimensionless capillary number is a good indicator of filling regime in real gravure printing. In addition, we also examine the effect of cell size on filling as this is important for increasing printing resolution. In the light of experimental and simulation results, we are able to rationalize the dominant failure in the filling process, i.e., air entrapment, which is caused by contact line pinning and interface deformation over the cell opening.

  9. Transmission electron microscopic examination of phosphoric acid fuel cell components

    Science.gov (United States)

    Pebler, A.

    1986-01-01

    Transmission electron microscopy (TEM) was used to physically characterize tested and untested phosphoric acid fuel cell (PAFC) components. Those examined included carbon-supported platinum catalysts, carbon backing paper, and Teflon-bonded catalyst layers at various stages of fabrication and after testing in pressurized PAFC's. Applicability of electron diffraction and electron energy loss spectroscopy for identifying the various phases was explored. The discussion focuses on the morphology and size distribution of platinum, the morphology and structural aspects of Teflon in catalyst layers, and the structural evidence of carbon corrosion. Reference is made to other physical characterization techniques where appropriate. A qualitative model of the catalyst layer that emerged from the TEM studies is presented.

  10. Electron Microscopy of Staphylococcus aureus Cell Wall Lysis

    Science.gov (United States)

    Virgilio, R.; González, C.; Muñoz, Nubia; Mendoza, Silvia

    1966-01-01

    Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018–2024. 1966.—A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents. Images PMID:5939482

  11. Effects of Horizontal Resolution on Cumulus Cloud Simulations

    Science.gov (United States)

    Lindsey, L.; Randall, D. A.; Dazlich, D.

    2012-12-01

    The horizontal resolution of cumulus cloud simulations not only affects the computational cost of running a cloud resolving model (CRM), but it affects the results of the model as well. It is necessary to find the coarsest resolution that can be used without compromising the accuracy of the results. This study was carried out using the System for Atmospheric Modeling (SAM), a three-dimensional cloud resolving model. The forcing data used for the model came from two different field campaigns, the GARP Atlantic Tropical Experiment (GATE) and Atmospheric Radiation Measurement Program (ARM) at the Southern Great Plains site. GATE took place during the summer of 1974 over the tropical Atlantic Ocean. The ARM field campaign took place during the summer of 1997. A constant large scale forcing was applied to the temperature and moisture fields for the GATE case. The model was run until the atmospheric water content stabilized. With the ARM forcing data, a diurnal cycle of solar insolation was applied. The model was run until the soil moisture adjusted. For both GATE and ARM, a 20-day period was analyzed. The effects of horizontal grid spacing on rainfall rates, updraft and downdraft velocities, and cloud cover are presented in this study. Grid spacings of 8 km, 4 km, 2 km, and 500 m were studied for the GATE runs, and 4 km, 2 km, 1 km, and 500 m were studied for the ARM runs. For the GATE runs, resolution does not have a great impact on rainfall rates. A more radical effect is seen on updrafts and downdrafts, which intensify with higher resolutions. The overall cloud cover for the GATE runs decrease with increased resolution. The ARM runs are more sensitive to horizontal resolution than the GATE runs. Domain averaged rainfall rates decrease with increased resolution. Local rainfall rates, on the contrary, increase with increased resolution. In the ARM runs updrafts and downdrafts intensify with increased resolution. Cloud cover decreases with increased resolution. Grid

  12. A new view into prokaryotic cell biology from electron cryotomography.

    Science.gov (United States)

    Oikonomou, Catherine M; Jensen, Grant J

    2016-04-01

    Electron cryotomography (ECT) enables intact cells to be visualized in 3D in an essentially native state to 'macromolecular' (∼4 nm) resolution, revealing the basic architectures of complete nanomachines and their arrangements in situ. Since its inception, ECT has advanced our understanding of many aspects of prokaryotic cell biology, from morphogenesis to subcellular compartmentalization and from metabolism to complex interspecies interactions. In this Review, we highlight how ECT has provided structural and mechanistic insights into the physiology of bacteria and archaea and discuss prospects for the future.

  13. Electron Microscopy of Living Cells During in Situ Fluorescence Microscopy.

    Science.gov (United States)

    Liv, Nalan; van Oosten Slingeland, Daan S B; Baudoin, Jean-Pierre; Kruit, Pieter; Piston, David W; Hoogenboom, Jacob P

    2016-01-26

    We present an approach toward dynamic nanoimaging: live fluorescence of cells encapsulated in a bionanoreactor is complemented with in situ scanning electron microscopy (SEM) on an integrated microscope. This allows us to take SEM snapshots on-demand, that is, at a specific location in time, at a desired region of interest, guided by the dynamic fluorescence imaging. We show that this approach enables direct visualization, with EM resolution, of the distribution of bioconjugated quantum dots on cellular extensions during uptake and internalization.

  14. CIF2Cell: Generating geometries for electronic structure programs

    Science.gov (United States)

    Björkman, Torbjörn

    2011-05-01

    The CIF2Cell program generates the geometrical setup for a number of electronic structure programs based on the crystallographic information in a Crystallographic Information Framework (CIF) file. The program will retrieve the space group number, Wyckoff positions and crystallographic parameters, make a sensible choice for Bravais lattice vectors (primitive or principal cell) and generate all atomic positions. Supercells can be generated and alloys are handled gracefully. The code currently has output interfaces to the electronic structure programs ABINIT, CASTEP, CPMD, Crystal, Elk, Exciting, EMTO, Fleur, RSPt, Siesta and VASP. Program summaryProgram title: CIF2Cell Catalogue identifier: AEIM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL version 3 No. of lines in distributed program, including test data, etc.: 12 691 No. of bytes in distributed program, including test data, etc.: 74 933 Distribution format: tar.gz Programming language: Python (versions 2.4-2.7) Computer: Any computer that can run Python (versions 2.4-2.7) Operating system: Any operating system that can run Python (versions 2.4-2.7) Classification: 7.3, 7.8, 8 External routines: PyCIFRW [1] Nature of problem: Generate the geometrical setup of a crystallographic cell for a variety of electronic structure programs from data contained in a CIF file. Solution method: The CIF file is parsed using routines contained in the library PyCIFRW [1], and crystallographic as well as bibliographic information is extracted. The program then generates the principal cell from symmetry information, crystal parameters, space group number and Wyckoff sites. Reduction to a primitive cell is then performed, and the resulting cell is output to suitably named files along with documentation of the information source generated from any bibliographic information contained in the CIF

  15. An evaluation of mass flux closures for diurnal cycles of shallow cumulus

    NARCIS (Netherlands)

    Neggers, R.A.J.; Siebesma, A.P.; Lenderink, G.; Holtslag, A.A.M.

    2004-01-01

    Three closure methods for the mass flux at cloud base in shallow cumulus convection are critically examined for the difficult case of a diurnal cycle over land. The closure methods are first evaluated against large-eddy simulations (LESs) by diagnosing all parameters appearing in the closure equatio

  16. Impacts of different cumulus physics over south Asia region with case study tropical cyclone Viyaru

    CERN Document Server

    Fahad, Abdullah Al

    2015-01-01

    Tropical Cyclone Viyaru, formerly known as Cyclonic Storm Mahasen was a rapidly intensifying, category 01B storm that made landfall in Chittagong, Bangladesh on the 16th of May, 2013. In this study, the sensitivity of numerical simulations of tropical cyclone to cumulus physics parametrization is carried out with a view to determine the best cumulus physics option for prediction of the cyclones track, timing, and central pressure evolution in the Bay of Bengal. For this purpose, the tropical cyclone Viyaru has been simulated by WRF ARW in a nested domain with NCEP Global Final Analysis(FNL) data as initial and boundary conditions. The model domain consists of one parent domain and one nested domain. The resolution of the parent domain is 36 km while the nested domain has a resolution of 12 km. Five numerical simulations have been done with the same micro-physics scheme (WSM3), planetary boundary layer scheme,NOAH land surface scheme but different Cumulus Parametrization scheme. Four cumulus Parametrization sc...

  17. Temperature Variable and the efficiency of sperm mediated transfection of HPV16DNAinto cells

    Institute of Scientific and Technical Information of China (English)

    RuslanaKadze; PhilipJ·Chan

    2002-01-01

    To pretreat sperm at various temperatures before exposure to human papillomavirus(HPV)16DNA fragments and to assess the efficiency of HPV carrier sperm to transfect cumulus cells.Methods:Cumulus cells from follicular aspirates were obtained,pooled and divided into culture dishes containing Syby Gold-stainedHPVDNA carrying spern that were either pretreated at4℃,37℃or40℃(n=5).The cells were incubated in5%Co2in air mixture at 37℃for 24hours.The effeiciency of sperm to take up fluorescent HPVDNAwas determined at hour0.After incubation.cumulus cell viability was assessed using the eosin method and the percentages of fluorescent cumulus cells determined.Results:Ouver half of all the cumulus cells became fluorescent with the highest percentage in the 37℃group.Sperm pretreated at 4℃had the greatest amount of HPVDNAfragmen ts.Total spern motility was similar for the3pretreatment groups.There were no differences in cumulus viability among the groups.Conclusion:Sperm pretreated at37℃transferred the greatest amount of fluorescent HPVDNAfragments to the cumulus cells.The HPVDNAwas observed in the nuclear and cytoplasmic compartments.The data suggested the possibility of sperm as a vector for the transmission of HPVDNAto the cumulus cells surrounding ovulated oocytes,which might lead to early implantation failures.

  18. Telocytes and putative stem cells in the lungs: electron microscopy, electron tomography and laser scanning microscopy.

    Science.gov (United States)

    Popescu, Laurentiu M; Gherghiceanu, Mihaela; Suciu, Laura C; Manole, Catalin G; Hinescu, Mihail E

    2011-09-01

    This study describes a novel type of interstitial (stromal) cell - telocytes (TCs) - in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com ). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles.

  19. Extending prematuration with cAMP modulators enhances the cumulus contribution to oocyte antioxidant defence and oocyte quality via gap junctions.

    Science.gov (United States)

    Li, H J; Sutton-McDowall, M L; Wang, X; Sugimura, S; Thompson, J G; Gilchrist, R B

    2016-04-01

    Can bovine oocyte antioxidant defence and oocyte quality be improved by extending the duration of pre-in vitro maturation (IVM) with cyclic adenosine mono-phosphate (cAMP) modulators? Lengthening the duration of cAMP-modulated pre-IVM elevates intra-oocyte reduced glutathione (GSH) content and reduces hydrogen peroxide (H2O2) via increased cumulus cell-oocyte gap-junctional communication (GJC), associated with an improvement in subsequent embryo development and quality. Oocytes are susceptible to oxidative stress and the oocyte's most important antioxidant glutathione is supplied, at least in part, by cumulus cells. A temporary inhibition of spontaneous meiotic resumption in oocytes can be achieved by preventing a fall in cAMP, and cyclic AMP-modulated pre-IVM maintains cumulus-oocyte GJC and improves subsequent embryo development. This study consisted of a series of 10 experiments using bovine oocytes in vitro, each with multiple replicates. A range of pre-IVM durations were examined as the key study treatments which were compared with a control. The study was designed to examine if one of the oocyte's major antioxidant defences can be enhanced by pre-IVM with cAMP modulators, and to examine the contribution of cumulus-oocyte GJC on these processes. Immature bovine cumulus-oocyte complexes were treated in vitro without (control) or with the cAMP modulators; 100 µM forskolin (FSK) and 500 µM 3-isobutyl-1-methyxanthine (IBMX), for 0, 2, 4 or 6 h (pre-IVM phase) prior to IVM. Oocyte developmental competence was assessed by embryo development and quality post-IVM/IVF. Cumulus-oocyte GJC, intra-oocyte GSH and H2O2 were quantified at various time points during pre-IVM and IVM, in the presence and the absence of functional inhibitors: carbenoxolone (CBX) to block GJC and buthionine sulfoximide (BSO) to inhibit glutathione synthesis. Pre-IVM with FSK + IBMX increased subsequent blastocyst formation rate and quality compared with standard IVM (P benefits of c

  20. Fundamental electronic mechanisms limiting the performance of solar cells

    Science.gov (United States)

    Lindholm, F. A.; Sah, C.-T.

    1977-01-01

    Attention is focused on distortion in the energy band, and carrier recombination and generation rates (lifetimes), as the two dominant mechanisms. Spatial dependences associated with these two mechanisms, in the direction normal to the surface illuminated by the sun and in the direction tangential to that surface, are also emphasized as crucial factors in governing the efficiency of solar cells. Electronic parameters for the set of differential equations characterizing transport, recombination, and generation of carriers, and interband and band-bound transition rates, are studied.

  1. An experimental electronic model for a neuronal cell

    Science.gov (United States)

    Campos-Cantón, I.; Rangel-López, A.; Martel-Gallegos, G.; Zarazúa, S.; Vertiz-Hérnandez, A.

    2014-04-01

    Over the last two decades, the study of information transmission in living beings has acquired great relevance, because it regulates and conducts the functioning of all of the organs in the body. In information transmission pathways, the neuron plays an important role in that it receives, transmits, and processes electrical signals from different parts of the human body; these signals are transmitted as electrical impulses called action potentials, and they transmit information from one neuron to another. In this work, and with the aim of developing experiments for teaching biological processes, we implemented an electronic circuit of the neuron cell device and its mathematical model based on piecewise linear functions.

  2. Direct Methanol Fuel Cell Prototype Demonstration for Consumer Electronics Applications

    Energy Technology Data Exchange (ETDEWEB)

    Carlstrom, Charles, M., Jr.

    2009-07-07

    This report is the final technical report for DOE Program DE-FC36-04GO14301 titled “Direct Methanol Fuel Cell Prototype Demonstration for Consumer Electronics Applications”. Due to the public nature of this report some of the content reported in confidential reports and meetings to the DOE is not covered in detail in this report and some of the content has been normalized to not show actual values. There is a comparison of the projects accomplishments with the objectives, an overview of some of the key subsystem work, and a review of the three levels of prototypes demonstrated during the program. There is also a description of the eventual commercial product and market this work is leading towards. The work completed under this program has significantly increased the understanding of how Direct Methanol Fuel Cells (DMFC) can be deployed successfully to power consumer electronic devices. The prototype testing has demonstrated the benefits a direct methanol fuel cell system has over batteries typically used for powering consumer electronic devices. Three generations of prototypes have been developed and tested for performance, robustness and life. The technologies researched and utilized in the fuel cell stack and related subsystems for these prototypes are leveraged from advances in other industries such as the hydrogen fueled PEM fuel cell industry. The work under this program advanced the state of the art of direct methanol fuel cells. The system developed by MTI micro fuel cells aided by this program differs significantly from conventional DMFC designs and offers compelling advantages in the areas of performance, life, size, and simplicity. The program has progressed as planned resulting in the completion of the scope of work and available funding in December 2008. All 18 of the final P3 prototypes builds have been tested and the results showed significant improvements over P2 prototypes in build yield, initial performance, and durability. The systems have

  3. Sensing lymphoma cells based on a cell-penetrating/apoptosis-inducing/electron-transfer peptide probe

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, Kazuharu, E-mail: kzsuga@maebashi-it.ac.jp [Maebashi Institute of Technology, Gunma 371-0816 (Japan); Shinohara, Hiroki; Kadoya, Toshihiko [Maebashi Institute of Technology, Gunma 371-0816 (Japan); Kuramitz, Hideki [Department of Environmental Biology and Chemistry, Graduate School of Science and Engineering for Research, University of Toyama, Toyama 930-8555 (Japan)

    2016-06-14

    To electrochemically sense lymphoma cells (U937), we fabricated a multifunctional peptide probe that consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. Electron-transfer peptides derive from cysteine residue combined with the C-terminals of four tyrosine residues (Y{sub 4}). A peptide whereby Y{sub 4}C is bound to the C-terminals of protegrin 1 (RGGRLCYCRRRFCVCVGR-NH{sub 2}) is known to be an apoptosis-inducing agent against U937 cells, and is referred to as a peptide-1 probe. An oxidation response of the peptide-1 probe has been observed due to a phenolic hydroxyl group, and this response is decreased by the uptake of the peptide probe into the cells. To improve the cell membrane permeability against U937 cells, the RGGR at the N-terminals of the peptide-1 probe was replaced by RRRR (peptide-2 probe). In contrast, RNRCKGTDVQAWY{sub 4}C (peptide-3 probe), which recognizes ovalbumin, was constructed as a control. Compared with the other probes, the change in the peak current of the peptide-2 probe was the greatest at low concentrations and occurred in a short amount of time. Therefore, the cell membrane permeability of the peptide-2 probe was increased based on the arginine residues and the apoptosis-inducing peptides. The peak current was linear and ranged from 100 to 1000 cells/ml. The relative standard deviation of 600 cells/ml was 5.0% (n = 5). Furthermore, the membrane permeability of the peptide probes was confirmed using fluorescent dye. - Highlights: • We constructed a multifunctional peptide probe for the electrochemical sensing of lymphoma cells. • The peptide probe consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. • The electrode response of the peptide probe changes due to selective uptake into the cells.

  4. One-Dimensional Electron Transport Layers for Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Ujwal K. Thakur

    2017-04-01

    Full Text Available The electron diffusion length (Ln is smaller than the hole diffusion length (Lp in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D structures such as nanowires (NWs and nanotubes (NTs as electron transport layers (ETLs is a promising method of achieving high performance halide perovskite solar cells (HPSCs. ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs. This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.

  5. One-Dimensional Electron Transport Layers for Perovskite Solar Cells

    Science.gov (United States)

    Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik

    2017-01-01

    The electron diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280

  6. Aerosol and Trace Gas Processing by Clouds During the Cumulus Humilis Aerosol Processing Study (CHAPS)

    Science.gov (United States)

    Yu, X.; Berg, L.; Berkowitz, C.; Alexander, L.; Lee, Y.; Ogren, J.; Andrews, B.

    2008-12-01

    Clouds play an active role in the processing and cycling of atmospheric constituents. Gases and particles can partition to cloud droplets by absorption and condensation as well as activation and pact scavenging. The Cumulus Humilis Aerosol Processing Study (CHAPS) aimed at characterizing freshly emitted aerosols above, within and below fields of cumulus humilis (or fair-weather cumulus) in the vicinity of Oklahoma City. The experiment took place in June 2007. Evolution of aerosol and cloud properties downwind of the Oklahoma City is of particular interest in this project. These observations of a mid-size and mid-latitude city can be used in the development and evaluation of regional-scale and global climate model cumulus parameterizations that describes the transport and transformations of these aerosols by fair-weather cumulus. The Department of Energy (DOE) G-1 aircraft was one of the main platforms used in CHAPS. It carried a suite of instruments to measure properties of interstitial aerosols behind an isokinetic inlet and a set of duplicate instruments to determine properties of activated particles behind a counter-flow virtual impactor (CVI). The sampling line to the Aerodyne Aerosol Mass Spectrometer was switched between the isokinetic inlet and the CVI to allow characterization of interstitial particles out of clouds in contrast to particles activated in clouds. Trace gases including ozone, carbon monoxide, sulfur dioxide, and a series of volatile organic compounds (VOCs) were also measured as were key meteorological state parameters including liquid water content, cloud drop size, and dew point temperature were measured. This presentation will focus on results related to the transformation and transport of aerosols and trace gases observed in fair-weather cumulus and compare these results with concurrent observations made outside these clouds. Our interest will focus on the differences in particle size and composition under varying conditions. The role of

  7. Case studies of size resolved CCN composition and cloud properties in cumulus humilis

    Science.gov (United States)

    Yu, X.; Berg, L. K.; Berkowitz, C. M.; Lee, Y.; Alexander, L.; Ogren, J. A.; Andrews, B.

    2010-12-01

    The Cumulus Humilis Aerosol Processing Study (CHAPS) provided a unique opportunity to study cloud processing of aerosols. Clouds play an active role in the processing and cycling of atmospheric constituents. Within in a cloud, gases and particles can partition to cloud droplets by absorption and condensation as well as activation and impact scavenging. The Department of Energy (DOE) G-1 aircraft was used as one of the main platforms in CHAPS. G-1 flight tracks were designed to characterize aerosols at cloud top and cloud base as well as within individual cumulus humilis (or fair-weather cumulus), in the vicinity of Oklahoma City. Measurements of interstitial aerosols and residuals of activated condensation cloud nuclei were conducted simultaneously. The interstitial aerosols were measured downstream of an isokinetic inlet, and the activated particles downstream of a counter-flow virtual impactor (CVI). The sampling line to the Aerodyne Aerosol Mass Spectrometer (AMS) was switched between the isokinetic inlet and the CVI to allow characterization of non-activated particles outside of clouds in contrast to particles activated in clouds. Trace gases including ozone, carbon monoxide, sulfur dioxide, and a series of volatile organic compounds (VOCs) were measured. Key meteorological state parameters included liquid water content, cloud drop size, and dew point. In this presentation, we will focus on case studies of CCN properties in cumulus humilis. The first analysis summarizes three case studies of measurements made at cloud bottom and in-cloud by the AMS. The size-resolved composition is different between background and activated particles. The second analysis links in situ measurements of aerosol, trace gas, and VOCs to look into the sources of CCN. For instance, by comparing the characteristic m/z ratios by AMS and tracers like CO or isoprene, one can gain more insight into the role of primary and secondary organic aerosols in CCN and background aerosols. The third

  8. A new approach for the oocyte genotoxicity assay: adaptation of comet assay on mouse cumulus-oocyte complexes.

    Science.gov (United States)

    Greco, F; Perrin, J; Auffan, M; Tassistro, V; Orsière, T; Courbiere, B

    2015-07-01

    Conventional genotoxicity tests are technically difficult to apply to oocytes, and results obtained on somatic cells cannot be extrapolated to gametes. We have previously described a comet assay (original-CA) on denuded mouse oocytes, but, in vivo, oocytes are not isolated from their surrounding follicular cells. Our objective was to develop a comet assay on cumulus-oocyte complexes (COC-CA) for a more physiological approach to study the genotoxicity of environmental factors on oocytes. For COC-CA, whole COC were exposed directly to exogenous agents after ovulation and removal from oviducts. Three conditions were studied: a negative control group, and two positive control groups, one of which was exposed to hydrogen peroxide (H2O2) and the other group was incubated with cerium dioxide nanoparticles (CeO2 NPs). With both tests, DNA damage was significant in the presence of both H2O2 and CeO2 NPs compared with the negative control. COC-CA offers an interesting tool for assaying the genotoxicity of environmental agents towards germinal cells. Furthermore, COC-CA is less time-consuming and simplifies the protocol of the original-CA, because COC-CA is easier to perform without the washing-out procedure.

  9. Modelling microbial fuel cells with suspended cells and added electron transfer mediator

    NARCIS (Netherlands)

    Picoreanu, C.; Katuri, K.P.; Van Loosdrecht, M.C.M.; Head, I.M.; Scott, K.

    2009-01-01

    Derivation of a mathematical model for microbial fuel cells (MFC) with suspended biomass and added electron-transfer mediator is described. The model is based on mass balances for several dissolved chemical species such as substrate, oxidized mediator and reduced mediator. Biological, chemical and e

  10. A holder assembly for cooperating with an environmental cell and an electron microscope

    NARCIS (Netherlands)

    Zandbergen, H.W.; Pleun, D.; Van Veen, G.N.A.

    2013-01-01

    The invention relates to a holder assembly for cooperating with an environmental cell ( 101 ) and an electron microscope, the environmental cell showing a fluid inlet (103), the electron microscope showing a vacuum wall (110) for separating an evacuable part of the electron microscope from the

  11. A holder assembly for cooperating with an environmental cell and an electron microscope

    NARCIS (Netherlands)

    Zandbergen, H.W.; Pleun, D.; Van Veen, G.N.A.

    2013-01-01

    The invention relates to a holder assembly for cooperating with an environmental cell ( 101 ) and an electron microscope, the environmental cell showing a fluid inlet (103), the electron microscope showing a vacuum wall (110) for separating an evacuable part of the electron microscope from the outsi

  12. Modeling of electron-electron collisions for particle-in-cell simulations

    Energy Technology Data Exchange (ETDEWEB)

    Andrea, D. d' ; Munz, C.D.; Schneider, R.

    2006-09-15

    The modeling of the physics of pulsed plasma thrusters requires the numerical solution of the Boltzmann equation for rarefied plasma flows where continuum assumptions fail. To tackle this challenging task, a cooperation between several institutes has been formed with the goal to develop a hybrid code based on Particle-In-Cell and Direct Simulation Monte Carlo techniques. These development activities are bundled in the project ''Numerische Simulation und Auslegung eines instationaeren gepulsten magnetoplasmadynamischen Triebwerks fuer eine Mondsonde'' which is funded by the Landesstiftung Baden-Wuerttemberg within the subject area ''Modellierung und Simulation auf Hochleistungscomputern''. In the frame of this project, the IHM is in charge to develop suitable physical-mathematical and numerical models to include charged particle collisions into the simulation. which can significantly affect the Parameters of such plasma devices. The intention of the present report is to introduce the Fokker-Planck approach for electron-electron interaction in Standard charged particle simulations. where the impact Parameter is usually large resulting in a small deflection angle. The theoretical and applicative framework is discussed in detail paying particular attention to the Particle-In-Cell approach in velocity space. a new technique which allows the self-consistent computation of the friction and diffusion coefficients arising from the Fokker-Planck treatment of collisions. These velocity-dependent coefficients thernselves are responsible for the change in velocity of the simulation particles, which is determined by the numerical solution of a Langevin-type equation. Simulation results for typical numerical experiments computed with the new developed Fokker-Planck solver are presented. demonstrating the quality. property and reliability of the applied numerical methods. (orig.)

  13. Use of scanning electron microscopy to monitor nanofibre/cell interaction in digestive epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Millaku, Agron, E-mail: agron.mi@hotmail.com [Limnos-Company for Applied Ecology Ltd, Podlimbarskega 31, 1000 Ljubljana (Slovenia); Drobne, Damjana [University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1000 Ljubljana (Slovenia); Centre of Excellence, Advanced Materials and Technologies for the Future (CO NAMASTE), Jamova cesta 39, 1000 Ljubljana (Slovenia); Centre of Excellence, Nanoscience and Nanotechnology (Nanocentre), Jamova cesta 39, 1000 Ljubljana (Slovenia); Torkar, Matjaz [Institute of Metals and Technology IMT, Lepi pot 11, 1000 Ljubljana (Slovenia); Jožef Stefan Institute, Condensed Matter Physics Department, Jamova cesta 39, 1000 Ljubljana (Slovenia); Novak, Sara [University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1000 Ljubljana (Slovenia); Remškar, Maja [Jožef Stefan Institute, Condensed Matter Physics Department, Jamova cesta 39, 1000 Ljubljana (Slovenia); Pipan-Tkalec, Živa [University of Ljubljana, Biotechnical Faculty, Department of Biology, Večna pot 111, 1000 Ljubljana (Slovenia)

    2013-09-15

    Graphical abstract: Scanning electron microscopy is particularly well suited to the observation of nanofibre/cell interaction in the endothelial cells lining the hepatopancreas. (a) Tungsten oxide nanofibres, (b) test organism Porcellio scaber and schematic appearance of digestive tubes, (c) digestive tube (hepatopancreas) prepared for SEM investigation, (d) digestive gland cells (C) with nanofibres (NF) embedded in the cell membrane and (e) nanofibres inserted deeply in the cells and damaged nanofibres due to peristalsis. -- Highlights: • Tungsten oxide nanofibres react physically with digestive gland epithelial cells in Porcellio scaber. • Physical peristaltic forces of lead to insertion of nanofibres into the cells. • No toxic responses as measured by conventional toxicity biomarkers were detected. • Physical interactions were observed in a majority of the investigated animals. -- Abstract: We provide data obtained by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells.

  14. Effects of cumulus entrainment and multiple cloud types on a January global climate model simulation

    Science.gov (United States)

    Yao, Mao-Sung; Del Genio, Anthony D.

    1989-01-01

    An improved version of the GISS Model II cumulus parameterization designed for long-term climate integrations is used to study the effects of entrainment and multiple cloud types on the January climate simulation. Instead of prescribing convective mass as a fixed fraction of the cloud base grid-box mass, it is calculated based on the closure assumption that the cumulus convection restores the atmosphere to a neutral moist convective state at cloud base. This change alone significantly improves the distribution of precipitation, convective mass exchanges, and frequencies in the January climate. The vertical structure of the tropical atmosphere exhibits quasi-equilibrium behavior when this closure is used, even though there is no explicit constraint applied above cloud base.

  15. Shallow-cumulus cloud feedback: model uncertainties and perspectives of observational constraint

    Science.gov (United States)

    Bony, Sandrine

    2017-04-01

    Shallow-cumulus clouds constitute the most prominent cloud type on Earth, and their response to changing environmental conditions is critical for climate sensitivity. Research over the last decade has pointed out the importance of the interplay between clouds, convection, turbulence and circulation in controlling this response. Unfortunately, numerical models represent this interplay in diverse ways, which translates into different shallow-cumulus cloud feedbacks in climate change. Climate models predict that the cloud-base cloud fraction is very sensitive to changes in environmental conditions, while process models suggest that it is very resilient to such changes. To understand and solve this contradiction, a field campaign named EUREC4A (Elucidating the role of clouds-circulation coupling in climate) will be organized in the lower Atlantic trades in Jan-Fev 2020. The scientific objectives of this campaign will be presented, and the experimental strategy envisioned to reach these objectives will be discussed.

  16. Transmission electron microscope cells for use with liquid samples

    Energy Technology Data Exchange (ETDEWEB)

    Khalid, Waqas; Alivisatos, Paul A.; Zettl, Alexander K.

    2016-08-09

    This disclosure provides systems, methods, and devices related to transmission electron microscopy cells for use with liquids. In one aspect a device includes a substrate, a first graphene layer, and a second graphene layer. The substrate has a first surface and a second surface. The first surface defines a first channel, a second channel, and an outlet channel. The first channel and the second channel are joined to the outlet channel. The outlet channel defines a viewport region forming a though hole in the substrate. The first graphene layer overlays the first surface of the substrate, including an interior area of the first channel, the second channel, and the outlet channel. The second graphene layer overlays the first surface of the substrate, including open regions defined by the first channel, the second channel, and the outlet channel.

  17. Observations of rapid aerosol optical depth enhancements in the vicinity of polluted cumulus clouds

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Arola, A.; Ferrare, R. A.; Hostetler, C. A.; Crumeyrolle, S. N.; Berkoff, T. A.; Welton, E. J.; Lolli, S.; Lyapustin, A.; Wang, Y.; Schafer, J. S.; Giles, D. M.; Anderson, B. E.; Thornhill, K. L.; Minnis, P.; Pickering, K. E.; Loughner, C. P.; Smirnov, A.; Sinyuk, A.

    2014-11-01

    During the July 2011 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field experiment in Maryland, significant enhancements in Aerosol Robotic Network (AERONET) sun-sky radiometer measured aerosol optical depth (AOD) were observed in the immediate vicinity of non-precipitating cumulus clouds on some days. Both measured Ångström exponents and aerosol size distribution retrievals made before, during and after cumulus development often suggest little change in fine mode particle size; therefore, implying possible new particle formation in addition to cloud processing and humidification of existing particles. In addition to sun-sky radiometer measurements of large enhancements of fine mode AOD, lidar measurements made from both ground-based and aircraft-based instruments during the experiment also measured large increases in aerosol signal at altitudes associated with the presence of fair weather cumulus clouds. These data show modifications of the aerosol vertical profile as a result of the aerosol enhancements at and below cloud altitudes. The airborne lidar data were utilized to estimate the spatial extent of these aerosol enhancements, finding increased AOD, backscatter and extinction out to 2.5 km distance from the cloud edge. Furthermore, in situ measurements made from aircraft vertical profiles over an AERONET site during the experiment also showed large increases in aerosol scattering and aerosol volume after cloud formation as compared to before. The 15-year AERONET database of AOD measurements at the Goddard Space Flight Center (GSFC), Maryland site, was investigated in order to obtain a climatological perspective of this phenomenon of AOD enhancement. Analysis of the diurnal cycle of AOD in summer showed significant increases in AOD from morning to late afternoon, corresponding to the diurnal cycle of cumulus development.

  18. Grading of Mammalian Cumulus Oocyte Complexes using Machine Learning for in Vitro Embryo Culture

    OpenAIRE

    Sudarshan, Viswanath P; Weiser, Tobias; Chintala, Phalgun; Mandal, Subhamoy; Dutta, Rahul

    2016-01-01

    Visual observation of Cumulus Oocyte Complexes provides only limited information about its functional competence, whereas the molecular evaluations methods are cumbersome or costly. Image analysis of mammalian oocytes can provide attractive alternative to address this challenge. However, it is complex, given the huge number of oocytes under inspection and the subjective nature of the features inspected for identification. Supervised machine learning methods like random forest with annotations...

  19. Mechanisms and Model Diversity of Trade-Wind Shallow Cumulus Cloud Feedbacks: A Review

    Science.gov (United States)

    Vial, Jessica; Bony, Sandrine; Stevens, Bjorn; Vogel, Raphaela

    2017-07-01

    Shallow cumulus clouds in the trade-wind regions are at the heart of the long standing uncertainty in climate sensitivity estimates. In current climate models, cloud feedbacks are strongly influenced by cloud-base cloud amount in the trades. Therefore, understanding the key factors controlling cloudiness near cloud-base in shallow convective regimes has emerged as an important topic of investigation. We review physical understanding of these key controlling factors and discuss the value of the different approaches that have been developed so far, based on global and high-resolution model experimentations and process-oriented analyses across a range of models and for observations. The trade-wind cloud feedbacks appear to depend on two important aspects: (1) how cloudiness near cloud-base is controlled by the local interplay between turbulent, convective and radiative processes; (2) how these processes interact with their surrounding environment and are influenced by mesoscale organization. Our synthesis of studies that have explored these aspects suggests that the large diversity of model responses is related to fundamental differences in how the processes controlling trade cumulus operate in models, notably, whether they are parameterized or resolved. In models with parameterized convection, cloudiness near cloud-base is very sensitive to the vigor of convective mixing in response to changes in environmental conditions. This is in contrast with results from high-resolution models, which suggest that cloudiness near cloud-base is nearly invariant with warming and independent of large-scale environmental changes. Uncertainties are difficult to narrow using current observations, as the trade cumulus variability and its relation to large-scale environmental factors strongly depend on the time and/or spatial scales at which the mechanisms are evaluated. New opportunities for testing physical understanding of the factors controlling shallow cumulus cloud responses using

  20. Evaluating the performance of microbial fuel cells powering electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Dewan, Alim; Beyenal, Haluk [Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Center for Environmental, Sediment and Aquatic Research, Pullman, WA (United States); Donovan, Conrad; Heo, Deukhyoun [School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99163-2710 (United States)

    2010-01-01

    A microbial fuel cell (MFC) is capable of powering an electronic device if we store the energy in an external storage device, such as a capacitor, and dispense that energy intermittently in bursts of high-power when needed. Therefore its performance needs to be evaluated using an energy-storing device such as a capacitor which can be charged and discharged rather than other evaluation techniques, such as continuous energy dissipation through a resistor. In this study, we develop a method of testing microbial fuel cell performance based on storing energy in a capacitor. When a capacitor is connected to a MFC it acts like a variable resistor and stores energy from the MFC at a variable rate. In practice the application of this method to testing microbial fuel cells is very challenging and time consuming; therefore we have custom-designed a microbial fuel cell tester (MFCT). The MFCT evaluates the performance of a MFC as a power source. It uses a capacitor as an energy storing device and waits until a desired amount of energy is stored then discharges the capacitor. The entire process is controlled using an analog-to-digital converter (ADC) board controlled by a custom-written computer program. The utility of our method and the MFCT is demonstrated using a laboratory microbial fuel cell (LMFC) and a sediment microbial fuel cell (SMFC). We determine (1) how frequently a MFC can charge a capacitor, (2) which electrode is current-limiting, (3) what capacitor value will allow the maximum harvested energy from a MFC, which is called the ''optimum charging capacitor value,'' and (4) what capacitor charging potential will harvest the maximum energy from a MFC, which is called the ''optimum charging potential.'' Using a LMFC we find that (1) the time needed to charge a 3-F capacitor from 0 to 500 mV is 108 min, (2) the optimum charging capacitor value is 3 F, and (3) the optimum charging potential is 300 mV. Using a SMFC we find that (1

  1. Use of scanning electron microscopy to monitor nanofibre/cell interaction in digestive epithelial cells.

    Science.gov (United States)

    Millaku, Agron; Drobne, Damjana; Torkar, Matjaz; Novak, Sara; Remškar, Maja; Pipan-Tkalec, Živa

    2013-09-15

    We provide data obtained by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells.

  2. Prevention of electron beam transmittance for biological cell imaging using electron beam excitation-assisted optical microscope

    Science.gov (United States)

    Fukuta, Masahiro; Nawa, Yasunori; Inami, Wataru; Kawata, Yoshimasa

    2017-04-01

    We demonstrated the high-spatial-resolution imaging of label-free biological cells using an electron beam excitation-assisted optical (EXA) microscope without irradiation damage by the electron beam. An EXA microscope can be used to observe a specimen with a nanometric light source excited in the Si3N4 membrane by an electron beam. The incident electron beam penetrates the Si3N4 membrane and damages the specimen. To suppress the irradiation damage of the specimen, we prevented the transmittance of the electron beam by coating the Si3N4 membrane with a gold thin film. To obtain an electron beam transmittance through the Si3N4 of 0%, a gold film of 15 nm thickness was required. By adding the gold layer, a label-free cellular structure was observed with 135-nm spatial resolution.

  3. Comparison of gene expression patterns between porcine cumulus ...

    African Journals Online (AJOL)

    UPuser

    1 Department of Gene and Cell Engineering, Institute of Animal Science, ... The benefit of this method lies in the small quantities of total RNA required for ..... supported by the “863 Project” from the Science and Technology Ministry of China.

  4. Cloud Condensation Nuclei in Cumulus Humilis - Selected Case Study During the CHAPS Campaign

    Science.gov (United States)

    Yu, X.; Berg, L. K.; Berkowitz, C. M.; Alexander, M. L.; Lee, Y.; Laskin, A.; Ogren, J. A.; Andrews, B.

    2009-12-01

    The Cumulus Humilis Aerosol Processing Study (CHAPS) provided a unique opportunity to study aerosol and cloud processing. Clouds play an active role in the processing and cycling of atmospheric constituents. Gases and particles can partition to cloud droplets by absorption and condensation as well as activation and pact scavenging. The Department of Energy (DOE) G-1 aircraft was used as one of the main platforms in CHAPS. Flight tracks were designed and implemented to characterize freshly emitted aerosols on cloud top and cloud base as well as with cloud, i.e., cumulus humilis (or fair-weather cumulus), in the vicinity of Oklahoma City. Measurements of interstitial aerosols and residuals of activated condensation cloud nuclei were conducted simultaneously. The interstitial aerosols were determined downstream of an isokinetic inlet; and the activated particles downstream of a counter-flow virtual impactor (CVI). The sampling line to the Aerodyne Aerosol Mass Spectrometer was switched between the isokinetic inlet and the CVI to allow characterization of interstitial particles out of clouds in contrast to particles activated in clouds. Trace gases including ozone, carbon monoxide, sulfur dioxide, and a series of volatile organic compounds (VOCs) were also measured as were key meteorological state parameters including liquid water content, cloud drop size, and dew point temperature were measured. This work will focus on studying CCN properties in cumulus humilis. Several approaches will be taken. The first is single particle analysis of particles collected by the Time-Resolved Aerosol Sampler (TRAC) by SEM/TEM coupled with EDX. We will specifically look into differences in particle properties such as chemical composition and morphology between activated and interstitial ones. The second analysis will link in situ measurements with the snap shots observations by TRAC. For instance, by looking into the characteristic m/z obtained by AMS vs. CO or isoprene, one can gain

  5. Bio-batteries and bio-fuel cells: leveraging on electronic charge transfer proteins.

    Science.gov (United States)

    Kannan, A M; Renugopalakrishnan, V; Filipek, S; Li, P; Audette, G F; Munukutla, L

    2009-03-01

    Bio-fuel cells are alternative energy devises based on bio-electrocatalysis of natural substrates by enzymes or microorganisms. Here we review bio-fuel cells and bio-batteries based on the recent literature. In general, the bio-fuel cells are classified based on the type of electron transfer; mediated electron transfer and direct electron transfer or electronic charge transfer (ECT). The ECT of the bio-fuel cells is critically reviewed and a variety of possible applications are considered. The technical challenges of the bio-fuel cells, like bioelectrocatalysis, immobilization of bioelectrocatalysts, protein denaturation etc. are highlighted and future research directions are discussed leveraging on the use of electron charge transfer proteins. In addition, the packaging aspects of the bio-fuel cells are also analyzed and the found that relatively little work has been done in the engineering development of bio-fuel cells.

  6. Two years results of electronic brachytherapy for basal cell carcinoma

    Directory of Open Access Journals (Sweden)

    Rosa Ballester-Sánchez

    2017-06-01

    Full Text Available Purpose: The use of radiation therapy (RT for non-melanoma skin cancer (NMSC has been changing throughout the last century. Over the last decades, the use of radiotherapy has surged with the development of new techniques, applicators, and devices. In recent years, electronic brachytherapy (eBT devices that use small x-ray sources have been introduced as alternative to radionuclide dependence. Nowadays, several devices have been incorporated, with a few series reported, and with a short follow-up, due to the recent introduction of these systems. The purpose of this work is to describe the clinical results of our series after two years follow-up with a specific eBT system. Material and methods: This is a prospective single-center, non-randomized pilot study, to assess clinical results of electronic brachytherapy in basal cell carcinoma using the Esteya® system. In 2014, 40 patients with 60 lesions were treated. Patient follow-up on a regular basis was performed for a period of two years. Results: Twenty-six patients with 44 lesions achieved two years follow-up. A complete response was documented in 95.5% of cases. Toxicity was mild (G1 or G2 in all cases, caused by erythema, erosion, or alopecia. Cosmesis was excellent in 88.6% of cases, and good in the rest. Change in pigmentation was the most frequent cosmetic alteration. Conclusions : This work is special, since the equipment’s treatment voltage was 69.5 kV, and this is the first prospective study with long term follow-up with Esteya®. These preliminary report show excellent results with less toxicity and excellent cosmesis. While surgery has been the treatment of choice, certain patients might benefit from eBT treatment. These are elderly patients with comorbidities or undergoing anticoagulant treatment as well as those who simply refuse surgery or might have other contraindications.

  7. Numerical Modeling of Microbial Fuel Cell Based on Redox Electron Mediator

    Institute of Scientific and Technical Information of China (English)

    Nanqi Ren

    2015-01-01

    To investigate the behavior of redox electron mediator and its impact to power generation of microbial fuel cell ( MFC ) , this study carries out the numerical modeling of a typical two⁃chamber MFC based on assumption of interfacial electron transfer via redox electron mediator and acetate as sole electron donor. The model simulates the development of cell voltage, current, substrate concentration, redox electron mediator concentration, polarization and power density output under defined conditions. The results demonstrate that the developed models can fit the experimental results well on a qualitative basis, and concentration of electron reduced mediator plays a dominant role in electron transfer process, and the mass transfer may constitute the limiting step when its concentration is at a relatively low level. This study not only provides a better understanding of electron redox mediator behavior during power generation, but also suggests a strategy to improve electron transfer in the anode of MFC.

  8. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by scanning electron microscopy

    NARCIS (Netherlands)

    Hartsuiker, L.; Es, van P.; Petersen, W.; Leeuwen, van T.G.; Terstappen, L.W.M.M.; Otto, C.

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  9. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by Scanning Electron Microscopy

    NARCIS (Netherlands)

    Hartsuiker, Liesbeth; van Es, Peter; Petersen, Wilhelmina; van Leeuwen, Ton; Terstappen, Leonardus Wendelinus Mathias Marie; Otto, Cornelis

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  10. Uptake of betaine into mouse cumulus-oocyte complexes via the SLC7A6 isoform of y+L transporter.

    Science.gov (United States)

    Corbett, Hannah E; Dubé, Chantal D; Slow, Sandy; Lever, Michael; Trasler, Jacquetta M; Baltz, Jay M

    2014-04-01

    Betaine (N,N,N-trimethylglycine) has previously been shown to function in cell volume homeostasis in early mouse embryos and also to be a key donor to the methyl pool in the blastocyst. A betaine transporter (SLC6A20A or SIT1) has been shown to be activated after fertilization, but there is no saturable betaine uptake in mouse oocytes or eggs. Unexpectedly, the same high level of betaine is present in mature metaphase II (MII) eggs as is found in one-cell embryos despite the lack of transport in oocytes or eggs. Significant saturable betaine transport is, however, present in intact cumulus-oocyte complexes (COCs). This transport system has an affinity for betaine of ∼227 μM. The inhibition profile indicates that betaine transport by COCs could be completely blocked by methionine, proline, leucine, lysine, and arginine, and transport is dependent on Na(+) but not Cl(-). This is consistent with transport by a y+L-type amino acid transport system. Both transcripts and protein of one y+L isoform, SLC7A6 (y+LAT2), are present in COCs, with little or no expression in isolated germinal vesicle (GV)-stage oocytes, MII eggs, or one-cell embryos. Betaine accumulated by COCs is transferred into the enclosed GV oocyte, which requires functional gap junctions. Thus, at least a portion of the endogenous betaine in MII eggs could be derived from transport into cumulus cells and subsequent transfer into the enclosed oocyte before gap junction closure during meiotic maturation. The oocyte-derived betaine then could be regulated and supplemented by the SIT1 transporter that arises in the embryo after fertilization.

  11. Electronic Safety Resource Tools -- Supporting Hydrogen and Fuel Cell Commercialization

    Energy Technology Data Exchange (ETDEWEB)

    Barilo, Nick F.

    2014-09-29

    The Pacific Northwest National Laboratory (PNNL) Hydrogen Safety Program conducted a planning session in Los Angeles, CA on April 1, 2014 to consider what electronic safety tools would benefit the next phase of hydrogen and fuel cell commercialization. A diverse, 20-person team led by an experienced facilitator considered the question as it applied to the eight most relevant user groups. The results and subsequent evaluation activities revealed several possible resource tools that could greatly benefit users. The tool identified as having the greatest potential for impact is a hydrogen safety portal, which can be the central location for integrating and disseminating safety information (including most of the tools identified in this report). Such a tool can provide credible and reliable information from a trustworthy source. Other impactful tools identified include a codes and standards wizard to guide users through a series of questions relating to application and specific features of the requirements; a scenario-based virtual reality training for first responders; peer networking tools to bring users from focused groups together to discuss and collaborate on hydrogen safety issues; and a focused tool for training inspectors. Table ES.1 provides results of the planning session, including proposed new tools and changes to existing tools.

  12. Electronic control of gene expression and cell behaviour in Escherichia coli through redox signalling

    Science.gov (United States)

    Tschirhart, Tanya; Kim, Eunkyoung; McKay, Ryan; Ueda, Hana; Wu, Hsuan-Chen; Pottash, Alex Eli; Zargar, Amin; Negrete, Alejandro; Shiloach, Joseph; Payne, Gregory F.; Bentley, William E.

    2017-01-01

    The ability to interconvert information between electronic and ionic modalities has transformed our ability to record and actuate biological function. Synthetic biology offers the potential to expand communication `bandwidth' by using biomolecules and providing electrochemical access to redox-based cell signals and behaviours. While engineered cells have transmitted molecular information to electronic devices, the potential for bidirectional communication stands largely untapped. Here we present a simple electrogenetic device that uses redox biomolecules to carry electronic information to engineered bacterial cells in order to control transcription from a simple synthetic gene circuit. Electronic actuation of the native transcriptional regulator SoxR and transcription from the PsoxS promoter allows cell response that is quick, reversible and dependent on the amplitude and frequency of the imposed electronic signals. Further, induction of bacterial motility and population based cell-to-cell communication demonstrates the versatility of our approach and potential to drive intricate biological behaviours.

  13. Regulation of fatty acid oxidation in mouse cumulus-oocyte complexes during maturation and modulation by PPAR agonists.

    Directory of Open Access Journals (Sweden)

    Kylie R Dunning

    Full Text Available Fatty acid oxidation is an important energy source for the oocyte; however, little is known about how this metabolic pathway is regulated in cumulus-oocyte complexes. Analysis of genes involved in fatty acid oxidation showed that many are regulated by the luteinizing hormone surge during in vivo maturation, including acyl-CoA synthetases, carnitine transporters, acyl-CoA dehydrogenases and acetyl-CoA transferase, but that many are dysregulated when cumulus-oocyte complexes are matured under in vitro maturation conditions using follicle stimulating hormone and epidermal growth factor. Fatty acid oxidation, measured as production of ³H₂O from [³H]palmitic acid, occurs in mouse cumulus-oocyte complexes in response to the luteinizing hormone surge but is significantly reduced in cumulus-oocyte complexes matured in vitro. Thus we sought to determine whether fatty acid oxidation in cumulus-oocyte complexes could be modulated during in vitro maturation by lipid metabolism regulators, namely peroxisome proliferator activated receptor (PPAR agonists bezafibrate and rosiglitazone. Bezafibrate showed no effect with increasing dose, while rosiglitazone dose dependently inhibited fatty acid oxidation in cumulus-oocyte complexes during in vitro maturation. To determine the impact of rosiglitazone on oocyte developmental competence, cumulus-oocyte complexes were treated with rosiglitazone during in vitro maturation and gene expression, oocyte mitochondrial activity and embryo development following in vitro fertilization were assessed. Rosiglitazone restored Acsl1, Cpt1b and Acaa2 levels in cumulus-oocyte complexes and increased oocyte mitochondrial membrane potential yet resulted in significantly fewer embryos reaching the morula and hatching blastocyst stages. Thus fatty acid oxidation is increased in cumulus-oocyte complexes matured in vivo and deficient during in vitro maturation, a known model of poor oocyte quality. That rosiglitazone further

  14. 75 FR 64248 - Approval for Manufacturing Authority Foreign-Trade Zone 196 ATC Logistics & Electronics (Cell...

    Science.gov (United States)

    2010-10-19

    ... & Electronics (Cell Phone Kitting) Fort Worth, TX Pursuant to its authority under the Foreign-Trade Zones Act of... following Order: Whereas, ATC Logistics & Electronics (ATCLE), an operator of Foreign-Trade Zone 196, has... procedures within FTZ 196 on behalf of ATC Logistics & Electronics, as described in the application...

  15. The effects of discontinuities in the Betts Miller cumulus convection scheme on four-dimensional variational data assimilation

    Science.gov (United States)

    Zupanski, Dušanka

    1993-10-01

    A tangent linear and an adjoint of the large-scale precipitation and the cumulus convection processes in the National Meteorological Center's NMC/ETA regional forecast model are developed. The effects of discontinuities in the Betts Miller cumulus convection scheme are examined and applicability of derivative minimization methods in four-dimensional variational (4D VAR) data assimilation is considered. It is demonstrated that discontinuities present in the control Betts Miller cumulus convection scheme increase linearization errors to a large extent and have adverse effects on 4D VAR data assimilation. In the experiments performed, discontinuities in the cumulus convection scheme have the most serious effect in low layers. These problems can be reduced by modifying the scheme to make it more continuous in low layers. Positive effects of inclusion of cumulus convection in 4D VAR data assimilation are found in upper layers, especially in humidity fields. The "observations" used are optimal interpolation analyses of temperature, surface pressure, wind and specific humidity. By inclusion of other data, more closely related to the convective processes, such as precipitation and clouds, more benefits should be expected. Even with the difficulties caused by discontinuities, derivative minimization techniques appear to work for the data assimilation problems. In order to get more general conclusions, more experiments are needed with different synoptic situations. The inclusion of other important physical processes such as radiation, surface friction and turbulence in the forecast and the corresponding adjoint models could alter the results since they may reinforce the effects of discontinuities.

  16. cyclic GMP Mediated Inhibition of Spontaneous Germinal Vesicle Breakdown Both with and without Cumulus in Mouse Oocyte.

    Science.gov (United States)

    Hwang, Heekyung; Cheon, Yong-Pil

    2016-12-01

    Intact germinal vesicle (GV) arrest and release are essential for maintaining the fertility of mammals inducing human. Intact germinal vesicle release, maturation of oocytes is maintained by very complex procedures along with folliculogenesis and is a critical step for embryonic development. Cyclic guanosine monophosphate (cGMP) has been suggested a key factor for meiotic arrest but so far its mechanisms are controversy. In this study we examine the effects of cGMP on germinal vesicle breakdown in cumulus-enclosed oocytes and denuded oocytes. Spontaneous maturation was inhibited by a cGMP agonist, 8-Br-cGMP with concentration dependent manners both in cumulus-enclosed oocytes and denuded oocytes. The inhibitory effect was more severe in denuded oocytes than cumulus-enclosed oocytes. The Rp-8-Br-cGMP and Rp-pCPT-8-Br-cGMP did not severely block GVB compared to 8-Br-cGMP. The spontaneous GVB inhibitory effects were different by the existence of cumulus. Based on them it is suggested that the cumulus modulates the role of cGMP in GV arrest.

  17. Microtubules in Plant Cells: Strategies and Methods for Immunofluorescence, Transmission Electron Microscopy and Live Cell Imaging

    Science.gov (United States)

    Celler, Katherine; Fujita, Miki; Kawamura, Eiko; Ambrose, Chris; Herburger, Klaus; Wasteneys, Geoffrey O.

    2016-01-01

    Microtubules are required throughout plant development for a wide variety of processes, and different strategies have evolved to visualize and analyze them. This chapter provides specific methods that can be used to analyze microtubule organization and dynamic properties in plant systems and summarizes the advantages and limitations for each technique. We outline basic methods for preparing samples for immunofluorescence labelling, including an enzyme-based permeabilization method, and a freeze-shattering method, which generates microfractures in the cell wall to provide antibodies access to cells in cuticle-laden aerial organs such as leaves. We discuss current options for live cell imaging of MTs with fluorescently tagged proteins (FPs), and provide chemical fixation, high pressure freezing/freeze substitution, and post-fixation staining protocols for preserving MTs for transmission electron microscopy and tomography. PMID:26498784

  18. Structural characterization of PTX3 disulfide bond network and its multimeric status in cumulus matrix organization.

    Science.gov (United States)

    Inforzato, Antonio; Rivieccio, Vincenzo; Morreale, Antonio P; Bastone, Antonio; Salustri, Antonietta; Scarchilli, Laura; Verdoliva, Antonio; Vincenti, Silvia; Gallo, Grazia; Chiapparino, Caterina; Pacello, Lucrezia; Nucera, Eleonora; Serlupi-Crescenzi, Ottaviano; Day, Anthony J; Bottazzi, Barbara; Mantovani, Alberto; De Santis, Rita; Salvatori, Giovanni

    2008-04-11

    PTX3 is an acute phase glycoprotein that plays key roles in resistance to certain pathogens and in female fertility. PTX3 exerts its functions by interacting with a number of structurally unrelated molecules, a capacity that is likely to rely on its complex multimeric structure stabilized by interchain disulfide bonds. In this study, PAGE analyses performed under both native and denaturing conditions indicated that human recombinant PTX3 is mainly composed of covalently linked octamers. The network of disulfide bonds supporting this octameric assembly was resolved by mass spectrometry and Cys to Ser site-directed mutagenesis. Here we report that cysteine residues at positions 47, 49, and 103 in the N-terminal domain form three symmetric interchain disulfide bonds stabilizing four protein subunits in a tetrameric arrangement. Additional interchain disulfide bonds formed by the C-terminal domain cysteines Cys(317) and Cys(318) are responsible for linking the PTX3 tetramers into octamers. We also identified three intrachain disulfide bonds within the C-terminal domain that we used as structural constraints to build a new three-dimensional model for this domain. Previously it has been shown that PTX3 is a key component of the cumulus oophorus extracellular matrix, which forms around the oocyte prior to ovulation, because cumuli from PTX3(-/-) mice show defective matrix organization. Recombinant PTX3 is able to restore the normal phenotype ex vivo in cumuli from PTX3(-/-) mice. Here we demonstrate that PTX3 Cys to Ser mutants, mainly assembled into tetramers, exhibited wild type rescue activity, whereas a mutant, predominantly composed of dimers, had impaired functionality. These findings indicate that protein oligomerization is essential for PTX3 activity within the cumulus matrix and implicate PTX3 tetramers as the functional molecular units required for cumulus matrix organization and stabilization.

  19. Effects of cumulus parameterization closures on simulations of summer precipitation over the continental United States

    Science.gov (United States)

    Qiao, Fengxue; Liang, Xin-Zhong

    2016-09-01

    This study examines the effects of five cumulus closure assumptions on simulations of summer precipitation in the continental U.S. by utilizing an ensemble cumulus parameterization (ECP) that incorporates multiple alternate closure schemes into a single cloud model formulation. Results demonstrate that closure algorithms significantly affect the summer mean, daily frequency and intensity, and diurnal variation of precipitation, with strong regional dependence. Overall, the vertical velocity (W) closure produces the smallest summer mean biases, while the moisture convergence (MC) closure most realistically reproduces daily variability. Both closures have advantages over others in simulating U.S. daily rainfall frequency distribution, though both slightly overestimate intense rain events. The MC closure is superior at capturing summer rainfall amount, daily variability, and heavy rainfall frequency over the Central U.S., but systematically produces wet biases over the North American Monsoon (NAM) region and Southeast U.S., which can be reduced by using the W closure. The instability tendency (TD) and the total instability adjustment (KF) closures are better at capturing observed diurnal signals over the Central U.S. and the NAM, respectively. The results reasonably explain the systematic behaviors of several major cumulus parameterizations. A preliminary experiment combining two optimal closures (averaged moisture convergence and vertical velocity) in the ECP scheme significantly reduced the wet (dry) biases over the Southeast U.S. in the summer of 1993 (2003), and greatly improved daily rainfall correlations over the NAM. Further improved model simulation skills may be achieved in the future if optimal closures and their appropriate weights can be derived at different time scales based on specific climate regimes.

  20. Numerical Simulation of Chennai Heavy Rainfall Using MM5 Mesoscale Model with Different Cumulus Parameterization Schemes

    Science.gov (United States)

    Litta, A. J.; Chakrapani, B.; Mohankumar, K.

    2007-07-01

    Heavy rainfall events become significant in human affairs when they are combined with hydrological elements. The problem of forecasting heavy precipitation is especially difficult since it involves making a quantitative precipitation forecast, a problem well recognized as challenging. Chennai (13.04°N and 80.17°E) faced incessant and heavy rain about 27 cm in 24 hours up to 8.30 a.m on 27th October 2005 completely threw life out of gear. This torrential rain caused by deep depression which lay 150km east of Chennai city in Bay of Bengal intensified and moved west north-west direction and crossed north Tamil Nadu and south Andhra Pradesh coast on 28th morning. In the present study, we investigate the predictability of the MM5 mesoscale model using different cumulus parameterization schemes for the heavy rainfall event over Chennai. MM5 Version 3.7 (PSU/NCAR) is run with two-way triply nested grids using Lambert Conformal Coordinates (LCC) with a nest ratio of 3:1 and 23 vertical layers. Grid sizes of 45, 15 and 5 km are used for domains 1, 2 and 3 respectively. The cumulus parameterization schemes used in this study are Anthes-Kuo scheme (AK), the Betts-Miller scheme (BM), the Grell scheme (GR) and the Kain-Fritsch scheme (KF). The present study shows that the prediction of heavy rainfall is sensitive to cumulus parameterization schemes. In the time series of rainfall, Grell scheme is in good agreement with observation. The ideal combination of the nesting domains, horizontal resolution and cloud parameterization is able to simulate the heavy rainfall event both qualitatively and quantitatively.

  1. Effects of cumulus parameterization closures on simulations of summer precipitation over the continental United States

    Science.gov (United States)

    Qiao, Fengxue; Liang, Xin-Zhong

    2017-07-01

    This study examines the effects of five cumulus closure assumptions on simulations of summer precipitation in the continental U.S. by utilizing an ensemble cumulus parameterization (ECP) that incorporates multiple alternate closure schemes into a single cloud model formulation. Results demonstrate that closure algorithms significantly affect the summer mean, daily frequency and intensity, and diurnal variation of precipitation, with strong regional dependence. Overall, the vertical velocity (W) closure produces the smallest summer mean biases, while the moisture convergence (MC) closure most realistically reproduces daily variability. Both closures have advantages over others in simulating U.S. daily rainfall frequency distribution, though both slightly overestimate intense rain events. The MC closure is superior at capturing summer rainfall amount, daily variability, and heavy rainfall frequency over the Central U.S., but systematically produces wet biases over the North American Monsoon (NAM) region and Southeast U.S., which can be reduced by using the W closure. The instability tendency (TD) and the total instability adjustment (KF) closures are better at capturing observed diurnal signals over the Central U.S. and the NAM, respectively. The results reasonably explain the systematic behaviors of several major cumulus parameterizations. A preliminary experiment combining two optimal closures (averaged moisture convergence and vertical velocity) in the ECP scheme significantly reduced the wet (dry) biases over the Southeast U.S. in the summer of 1993 (2003), and greatly improved daily rainfall correlations over the NAM. Further improved model simulation skills may be achieved in the future if optimal closures and their appropriate weights can be derived at different time scales based on specific climate regimes.

  2. Investigating the scale-adaptivity of a shallow cumulus parameterization scheme with LES

    Science.gov (United States)

    Brast, Maren; Schemann, Vera; Neggers, Roel

    2017-04-01

    In this study we investigate the scale-adaptivity of a new parameterization scheme for shallow cumulus clouds in the gray zone. The Eddy-Diffusivity Multiple Mass-Flux (or ED(MF)n ) scheme is a bin-macrophysics scheme, in which subgrid transport is formulated in terms of discretized size densities. While scale-adaptivity in the ED-component is achieved using a pragmatic blending approach, the MF-component is filtered such that only the transport by plumes smaller than the grid size is maintained. For testing, ED(MF)n is implemented in a large-eddy simulation (LES) model, replacing the original subgrid-scheme for turbulent transport. LES thus plays the role of a non-hydrostatic testing ground, which can be run at different resolutions to study the behavior of the parameterization scheme in the boundary-layer gray zone. In this range convective cumulus clouds are partially resolved. We find that at high resolutions the clouds and the turbulent transport are predominantly resolved by the LES, and the transport represented by ED(MF)n is small. This partitioning changes towards coarser resolutions, with the representation of shallow cumulus clouds becoming exclusively carried by the ED(MF)n. The way the partitioning changes with grid-spacing matches the results of previous LES studies, suggesting some scale-adaptivity is captured. Sensitivity studies show that a scale-inadaptive ED component stays too active at high resolutions, and that the results are fairly insensitive to the number of transporting updrafts in the ED(MF)n scheme. Other assumptions in the scheme, such as the distribution of updrafts across sizes and the value of the area fraction covered by updrafts, are found to affect the location of the gray zone.

  3. Sensitivity of PBL and Cumulus schemes for Thunderstorm prediction over an Indian Region

    Science.gov (United States)

    Kumar, Dinesh; Charan Mohanty, Uma; Kumar, Krishan

    2015-04-01

    The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL). How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme) and WSM-6 (Cumulus Scheme) have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6, and KF schemes

  4. A case study of cumulus formation beneath a stratocumulus sheet: Its structure and effect on boundary layer budgets

    Science.gov (United States)

    Barlow, Roy W.; Nicholls, S.

    1990-01-01

    On several occasions during the FIRE Marine Stratocumulus IFO off the California coast, small cumulus were observed to form during the morning beneath the main stratocumulus (Sc) deck. This occurs in the type of situation described by Turton and Nicholls (1987) in which there is insufficient generation of turbulent kinetic energy (TKE) from the cloudtop or the surface to sustain mixing throughout the layer, and a separation of the surface and cloud layers occurs. The build up of humidity in the surface layer allows cumuli to form, and the more energetic of these may penetrate back into the Sc deck, reconnecting the layers. The results presented were collected by the UKMO C-130 aircraft flying in a region where these small cumulus had grown to the extent that they had penetrated into the main Sc deck above. The structure of these penetrative cumulus are examined and their implications on the layer flux and radiation budget discussed.

  5. An overview of electron acceptors in microbial fuel cells

    DEFF Research Database (Denmark)

    Ucar, Deniz; Zhang, Yifeng; Angelidaki, Irini

    2017-01-01

    as an electron acceptor due to its high oxidation potential and ready availability. Recent studies, however, have begun to assess the use of different electron acceptors because of the (1) diversity of redox potential, (2) needs of alternative and more efficient cathode reaction, and (3) expanding of MFC based...

  6. In Vitro Maturation of Cumulus-Oocyte Complexes for Efficient Isolation of Oocytes from Outbred Deer Mice

    Science.gov (United States)

    Choi, Jung Kyu; He, Xiaoming

    2013-01-01

    Background The outbred (as with humans) deer mice have been a useful animal model of research on human behavior and biology including that of the reproductive system. One of the major challenges in using this species is that the yield of oocyte isolation via superovulation is dismal according to the literature to date less than ∼5 oocytes per animal can be obtained so far. Objective The goal of this study is to improve the yield of oocyte isolation from outbred deer mice close to that of most laboratory mice by in vitro maturation (IVM) of cumulus-oocyte complexes (COCs). Methods Oocytes were isolated by both superovulation and IVM. For the latter, COCs were obtained by follicular puncture of antral follicles in both the surface and inner cortical layers of ovaries. Immature oocytes in the COCs were then cultured in vitro under optimized conditions to obtain metaphase II (MII) oocytes. Quality of the oocytes from IVM and superovulation was tested by in vitro fertilization (IVF) and embryo development. Results Less than ∼5 oocytes per animal could be isolated by superovulation only. However, we successfully obtained 20.3±2.9 oocytes per animal by IVM (16.0±2.5) and superovulation (4.3±1.3) in this study. Moreover, IVF and embryo development studies suggest that IVM oocytes have even better quality than that from superovulation The latter never developed to beyond 2-cell stage as usual while 9% of the former developed to 4-cells. Significance We have successfully established the protocol for isolating oocytes from deer mice with high yield by IVM. Moreover, this is the first ever success to develop in vitro fertilized deer mice oocytes beyond the 2-cell stage in vitro. Therefore, this study is of significance to the use of deer mice for reproductive biology research. PMID:23457518

  7. In vitro maturation of cumulus-oocyte complexes for efficient isolation of oocytes from outbred deer mice.

    Directory of Open Access Journals (Sweden)

    Jung Kyu Choi

    Full Text Available BACKGROUND: The outbred (as with humans deer mice have been a useful animal model of research on human behavior and biology including that of the reproductive system. One of the major challenges in using this species is that the yield of oocyte isolation via superovulation is dismal according to the literature to date less than ∼5 oocytes per animal can be obtained so far. OBJECTIVE: The goal of this study is to improve the yield of oocyte isolation from outbred deer mice close to that of most laboratory mice by in vitro maturation (IVM of cumulus-oocyte complexes (COCs. METHODS: Oocytes were isolated by both superovulation and IVM. For the latter, COCs were obtained by follicular puncture of antral follicles in both the surface and inner cortical layers of ovaries. Immature oocytes in the COCs were then cultured in vitro under optimized conditions to obtain metaphase II (MII oocytes. Quality of the oocytes from IVM and superovulation was tested by in vitro fertilization (IVF and embryo development. RESULTS: Less than ∼5 oocytes per animal could be isolated by superovulation only. However, we successfully obtained 20.3±2.9 oocytes per animal by IVM (16.0±2.5 and superovulation (4.3±1.3 in this study. Moreover, IVF and embryo development studies suggest that IVM oocytes have even better quality than that from superovulation The latter never developed to beyond 2-cell stage as usual while 9% of the former developed to 4-cells. SIGNIFICANCE: We have successfully established the protocol for isolating oocytes from deer mice with high yield by IVM. Moreover, this is the first ever success to develop in vitro fertilized deer mice oocytes beyond the 2-cell stage in vitro. Therefore, this study is of significance to the use of deer mice for reproductive biology research.

  8. Temperature and 8 MeV electron irradiation effects on GaAs solar cells

    Indian Academy of Sciences (India)

    Asha Rao; Sheeja Krishnan; Ganesh Sajeev; K Siddappa

    2010-06-01

    GaAs solar cells hold the record for the highest single band-gap cell efficiency. Successful application of these cells in advanced space-borne systems demand characterization of cell properties like dark current under different ambient conditions and the stability of the cells against particle irradiation in space. In this paper, the results of the studies carried out on the effect of 8 MeV electron irradiation on the electrical properties of GaAs solar cells are presented. The – (current–voltage) characteristics of the cells under dark and AM1.5 illumination condition are studied and 8 MeV electron irradiation was carried out on the cells where they were exposed to graded doses of electrons from 1 to 100 kGy. The devices were also characterized using capacitance measurements at various frequencies before and after irradiation. The effect of electron irradiation on the solar cell parameters was studied. It is found that only small changes were observed in the GaAs solar cell parameters up to an electron dose of 100 kGy, exhibiting good tolerance for electrons of 8 MeV energy.

  9. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by scanning electron microscopy.

    Science.gov (United States)

    Hartsuiker, L; VAN Es, P; Petersen, W; VAN Leeuwen, T G; Terstappen, L W M M; Otto, C

    2011-11-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample preparation protocol was developed to enable imaging of cells and gold nanoparticles with a conventional below lens scanning electron microscopes. The negative influence of 'charging' on the quality of scanning electron microscopes' images could be limited by deposition of biological cells on a conductive (gold) surface. The novel protocol enabled high-resolution scanning electron microscopes' imaging of small clusters and individual gold nanoparticles on uncoated cell surfaces. Gold nanoparticles could be counted on cancer cells with automated routines.

  10. Cell-level battery charge/discharge protection system. [electronic control techniques

    Science.gov (United States)

    Donovan, R. L.; Imamura, M. S.

    1977-01-01

    The paper describes three design approaches to individual cell monitoring and control for sealed secondary battery cells. One technique involves a modular strap-on single cell protector which contains all the electronics required for monitoring cell voltage, responding to external commands, and forming a bypass circuit for the cell. A second technique, the multiplexed cell protector, uses common circuitry to monitor and control each cell in a battery pack. The third technique, the computerized cell protector, by replacing the hard-wired logic of the multiplexed cell protector with a microprocessor, achieves greatest control flexibility and inherent computational capability with a minimum parts count implementation.

  11. NPPC/NPR2 signaling is essential for oocyte meiotic arrest and cumulus oophorus formation during follicular development in the mouse ovary.

    Science.gov (United States)

    Kiyosu, Chiyo; Tsuji, Takehito; Yamada, Kaoru; Kajita, Shimpei; Kunieda, Tetsuo

    2012-08-01

    Natriuretic peptide type C (NPPC) and its high affinity receptor, natriuretic peptide receptor 2 (NPR2), have been assumed to be involved in female reproduction and have recently been shown to play an essential role in maintaining meiotic arrest of oocytes. However, the overall role of NPPC/NPR2 signaling in female reproduction and ovarian function is still less clear. Here we report the defects observed in oocytes and follicles of mice homozygous for Nppc(lbab) or Npr2(cn), mutant alleles of Nppc or Npr2 respectively to clarify the exact consequences of lack of NPPC/NPR2 signaling in female reproductive systems. We found that: i) Npr2(cn)/Npr2(cn) female mice ovulated a comparable number of oocytes as normal mice but never produced a litter; ii) all ovulated oocytes of Npr2(cn)/Npr2(cn) and Nppc(lbab)/Nppc(lbab) mice exhibited abnormalities, such as fragmented or degenerated ooplasm and never developed to the two-cell stage after fertilization; iii) histological examination of the ovaries of Npr2(cn)/Npr2(cn) and Nppc(lbab)/Nppc(lbab) mice showed that oocytes in antral follicles prematurely resumed meiosis and that immediately before ovulation, oocytes showed disorganized chromosomes or fragmented ooplasm; and iv) ovulated oocytes and oocytes in the periovulatory follicles of the mutant mice were devoid of cumulus cells. These findings demonstrate that NPPC/NPR2 signaling is essential for oocyte meiotic arrest and cumulus oophorus formation, which affects female fertility through the production of oocytes with developmental capacity.

  12. Project Overview: Cumulus Humilis Aerosol Processing Study (CHAPS): Proposed Summer 2007 ASP Field Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, Carl M.; Berg, Larry K.; Ogren, J. A.; Hostetler, Chris A.; Ferrare, Richard

    2006-05-18

    This white paper presents the scientific motivation and preliminary logistical plans for a proposed ASP field campaign to be carried out in the summer of 2007. The primary objective of this campaign is to use the DOE Gulfstream-1 aircraft to make measurements characterizing the chemical, physical and optical properties of aerosols below, within and above large fields of fair weather cumulus and to use the NASA Langley Research Center’s High Spectral Resolution Lidar (HSRL) to make independent measurements of aerosol backscatter and extinction profiles in the vicinity of these fields. Separate from the science questions to be addressed by these observations will be information to add in the development of a parameterized cumulus scheme capable of including multiple cloud fields within a regional or global scale model. We will also be able to compare and contrast the cloud and aerosol properties within and outside the Oklahoma City plume to study aerosol processes within individual clouds. Preliminary discussions with the Cloud and Land Surface Interaction Campaign (CLASIC) science team have identified overlap between the science questions posed for the CLASIC Intensive Operation Period (IOP) and the proposed ASP campaign, suggesting collaboration would benefit both teams.

  13. China summer precipitation simulations using an optimal ensemble of cumulus schemes

    Institute of Scientific and Technical Information of China (English)

    Shuyan LIU; Wei GAO; Min XU; Xueyuan WANG; Xin-Zhong LIANG

    2009-01-01

    RegCM3 (REGional Climate Model) simulations of precipitation in China in 1991 and 1998 are very sensitive to the cumulus parameterization. Among the four schemes available, none has superior skills over the whole of China, but each captures certain observed signals in distinct regions. The Grell scheme with the FritschChappell closure produces the smallest biases over the North; the Grell scheme with the Arakawa-Schubert closure performs the best over the southeast of 100°E;the Anthes-Kuo scheme is superior over the northeast; and the Emanuel scheme is more realistic over the southwest of 100~E and along the Yangtze River Basin. These differences indicate a strong degree of independence and complementarity between the parameterizations. As such,an ensemble is developed from the four schemes, whose relative contributions or weights are optimized locally to yield overall minimum root-mean-square errors from observed daily precipitation. The skill gain is evaluated by applying the identical distribution of the weights in a different period. It is shown that the ensemble always produces gross biases that are smaller than the individual schemes in both 1991 and 1998. The ensemble, however,cannot eliminate the large rainfall deficits over the southwest of 100°E and along the Yangtze River Basin that are systematic across all schemes. Further improvements can be made by a super-ensemble based on more cumulus schemes and/or multiple models.

  14. Laboratory simulations show diabatic heating drives cumulus-cloud evolution and entrainment.

    Science.gov (United States)

    Narasimha, Roddam; Diwan, Sourabh Suhas; Duvvuri, Subrahmanyam; Sreenivas, K R; Bhat, G S

    2011-09-27

    Clouds are the largest source of uncertainty in climate science, and remain a weak link in modeling tropical circulation. A major challenge is to establish connections between particulate microphysics and macroscale turbulent dynamics in cumulus clouds. Here we address the issue from the latter standpoint. First we show how to create bench-scale flows that reproduce a variety of cumulus-cloud forms (including two genera and three species), and track complete cloud life cycles--e.g., from a "cauliflower" congestus to a dissipating fractus. The flow model used is a transient plume with volumetric diabatic heating scaled dynamically to simulate latent-heat release from phase changes in clouds. Laser-based diagnostics of steady plumes reveal Riehl-Malkus type protected cores. They also show that, unlike the constancy implied by early self-similar plume models, the diabatic heating raises the Taylor entrainment coefficient just above cloud base, depressing it at higher levels. This behavior is consistent with cloud-dilution rates found in recent numerical simulations of steady deep convection, and with aircraft-based observations of homogeneous mixing in clouds. In-cloud diabatic heating thus emerges as the key driver in cloud development, and could well provide a major link between microphysics and cloud-scale dynamics.

  15. Observations of sulfur dioxide uptake and new particle formation in a midlatitude cumulus cloud

    Science.gov (United States)

    Peter, J. R.; Siems, S. T.; Jensen, J. B.; Gras, J. L.; Ishizaka, Y.; Hacker, J. M.

    2006-08-01

    Airborne measurements, obtained during the Asian Aerosol Characterisation Experiment (ACE-Asia), of SO2 and condensation nuclei (CN) concentrations were made in the local environment of a cumulus cloud band. Conserved quantities, wet equivalent potential temperature θq, and total water content Q, were used to identify the sources of air detrained on the downwind side of the cumulus band. It was found that ~65% of the detrained air originated from below cloud base and the remainder was air that had been entrained from the free troposphere upwind of the cloud and subsequently been detrained. Calculation of the sources of the detrained air parcels enabled a prediction of the concentration of SO2 and CN, assuming that SO2 and CN experienced no processing within cloud. A comparison of the predicted concentration of SO2 and CN was made with those observed. The concentration of SO2 observed was less than predicted and the amount of SO2 scavenged within cloud was calculated. The CN concentration observed was also less than predicted and, moreover, inclusion of the loss of CN to cloud droplets due to Brownian scavenging resulted in an enhanced decrease of the number concentration of CN predicted. Clear air regions around the cloud exhibited no indication of being a major source of new particles. It was concluded that new particles were formed within cloud.

  16. Induction of retrovirus particles in human testicular tumor (Tera-1) cell cultures: an electron microscopic study.

    Science.gov (United States)

    Bronson, D L; Fraley, E E; Fogh, J; Kalter, S S

    1979-08-01

    The Tera-1 and Tera-2 cell lines, established from germ-cell tumors of the human testis, were examined by electron microscopy for particles with the morphology of retroviruses. Extracellular and budding particles were observed at low frequencies only in cultures of Tera-1 cells that had been treated with 5-iodo-2'-deoxyuridine and dexamethasone. No particles were detected in untreated cultures of Tera-1 cells or in any preparations of Tera-2 cells.

  17. Riboflavin-shuttled extracellular electron transfer from Enterococcus faecalis to electrodes in microbial fuel cells.

    Science.gov (United States)

    Zhang, Enren; Cai, Yamin; Luo, Yue; Piao, Zhe

    2014-11-01

    Great attention has been focused on Gram-negative bacteria in the application of microbial fuel cells. In this study, the Gram-positive bacterium Enterococcus faecalis was employed in microbial fuel cells. Bacterial biofilms formed by E. faecalis ZER6 were investigated with respect to electricity production through the riboflavin-shuttled extracellular electron transfer. Trace riboflavin was shown to be essential for transferring electrons derived from the oxidation of glucose outside the peptidoglycan layer in the cell wall of E. faecalis biofilms formed on the surface of electrodes, in the absence of other potential electron mediators (e.g., yeast extract).

  18. Enhanced Performance of Dye-Sensitized Solar Cells with Nanostructure Graphene Electron Transfer Layer

    Directory of Open Access Journals (Sweden)

    Chih-Hung Hsu

    2014-01-01

    Full Text Available The utilization of nanostructure graphene thin films as electron transfer layer in dye-sensitized solar cells (DSSCs was demonstrated. The effect of a nanostructure graphene thin film in DSSC structure was examined. The nanostructure graphene thin films provides a great electron transfer channel for the photogenerated electrons from TiO2 to indium tin oxide (ITO glass. Obvious improvements in short-circuit current density of the DSSCs were observed by using the graphene electron transport layer modified photoelectrode. The graphene electron transport layer reduces effectively the back reaction in the interface between the ITO transparent conductive film and the electrolyte in the DSSC.

  19. Survival of tumor and normal cells upon targeting with electron-emitting radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Rajon, Didier; Bolch, Wesley E.; Howell, Roger W. [Department of Neurosurgery, University of Florida, Gainesville, Florida 32611 (United States); Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States); Department of Radiology, Division of Radiation Research, UMDNJ-New Jersey Medical School Cancer Center, Newark, New Jersey 07103 (United States)

    2013-01-15

    Purpose: Previous studies have shown that the mean absorbed dose to a tissue element may not be a suitable quantity for correlating with the biological response of cells in that tissue element. Cell survival can depend strongly on the distribution of radioactivity at the cellular and multicellular levels. Furthermore, when cellular absorbed doses are examined, the cross-dose from neighbor cells can be less radiotoxic than the self-dose component. To better understand how the nonuniformity of activity among cells can affect the dose response, a computer model of a 3D tissue culture was previously constructed and showed that activity distribution among cells is significantly more relevant than the mean absorbed dose for low-energy-electron emitters. The present work greatly expands upon those findings. Methods: In the present study, we used this same computer model but restricted the number of labeled cells to a fraction of the whole cell population (50%, 10%, and 1%, respectively). The labeled cells were randomly distributed among the whole cell population. Results: While the activity distribution is an important factor in determining the tissue response for low-energy-electron emitters, the fraction of labeled cells has an even more pronounced effect on survival response. For all electron energies studied, reducing the percentage of cells labeled significantly increases the surviving fraction of the whole population. Conclusions: This study provides abundant information on killing tumor and normal cells under some conditions relevant to targeted radionuclide therapy of isolated tumor cells and micrometastases. The percentage of cells labeled, activity distribution among the labeled cells, and electron energy play key roles in determining their response. Most importantly, and not previously demonstrated, lognormal activity distributions can have a profound impact on the response of the tumor cells even when the radionuclide emits high-energy electrons.

  20. Interstitial cells of Cajal and Auerbach's plexus. A scanning electron microscopical study of guinea-pig small intestine

    DEFF Research Database (Denmark)

    Jessen, Harry; Thuneberg, Lars

    1991-01-01

    Anatomy, interstitial cells of Cajal, myenteric plexus, small intestine, guinea-pig, scanning electron microscopy......Anatomy, interstitial cells of Cajal, myenteric plexus, small intestine, guinea-pig, scanning electron microscopy...

  1. Electron microscopy localization and characterization of functionalized composite organic-inorganic SERS nanoparticles on leukemia cells

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Ai Leen [Department of Materials Science and Engineering, Stanford University, Durand Building Room 139, 496 Lomita Mall, Stanford, CA 94305 (United States); Stanford Nanocharacterization Laboratory, Stanford University, Stanford, CA 94305 (United States); Department of Mechanical Engineering, Stanford University, Stanford, CA 94305 (United States)], E-mail: alkoh@stanford.edu; Shachaf, Catherine M.; Elchuri, Sailaja; Nolan, Garry P. [Baxter Laboratory in Genetic Pharmacology, Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305 (United States); Sinclair, Robert [Department of Materials Science and Engineering, Stanford University, Durand Building Room 139, 496 Lomita Mall, Stanford, CA 94305 (United States); Stanford Nanocharacterization Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2008-12-15

    We demonstrate the use of electron microscopy as a powerful characterization tool to identify and locate antibody-conjugated composite organic-inorganic nanoparticle (COINs) surface enhanced Raman scattering (SERS) nanoparticles on cells. U937 leukemia cells labeled with antibody CD54-conjugated COINs were characterized in their native, hydrated state using wet scanning electron microscopy (SEM) and in their dehydrated state using high-resolution SEM. In both cases, the backscattered electron (BSE) detector was used to detect and identify the silver constituents in COINs due to its high sensitivity to atomic number variations within a specimen. The imaging and analytical capabilities in the SEM were further complemented by higher resolution transmission electron microscopy (TEM) images and scanning Auger electron spectroscopy (AES) data to give reliable and high-resolution information about nanoparticles and their binding to cell surface antigens.

  2. Non-fullerene organic solar cells based on diketopyrrolopyrrole polymers as electron donors and ITIC as an electron acceptor.

    Science.gov (United States)

    Jiang, Xudong; Xu, Yunhua; Wang, Xiaohui; Wu, Yang; Feng, Guitao; Li, Cheng; Ma, Wei; Li, Weiwei

    2017-03-15

    In this work, we provide systematic studies on the non-fullerene solar cells based on diketopyrrolopyrrole (DPP) polymers as electron donors and a well-known electron acceptor ITIC. ITIC has been widely reported in non-fullerene solar cells with high power conversion efficiencies (PCEs) above 10%, when it is combined with a wide band gap conjugated polymer, while its application in small band gap DPP polymers has never been reported. Herein, we select four DPP polymers containing different thienyl linkers, resulting in distinct absorption spectra, energy levels and crystalline properties. Non-fullerene solar cells based on DPP polymers as donors and ITIC as an acceptor show PCEs of 1.9-4.1% and energy loss of 0.55-0.82 eV. The PCEs are much lower than those of cells based on fullerene derivatives due to the poor miscibility between the DPP polymers and ITIC, as confirmed by the morphology and charge transport investigation. The results indicate that it is important to tune the miscibility between the donor and acceptor in order to realize optimized micro-phase separation, which can further enhance the performance of DPP polymer based non-fullerene solar cells.

  3. Nanoparticle Facilitated Extracellular Electron Transfer in Microbial Fuel Cells

    Science.gov (United States)

    2014-10-13

    tances.19 Nanoscale materials and devices, such as metal /semi- conductor nanoparticles, nanowires, and carbon nanotubes, have been widely exploited...redox centers. In addition, dissimilatory intermembrane and intramembrane reduction of metals into nanoparticles has been well-documented29,30...different length scales. Biomineralized iron sulfide was employed for the current studies because of the importance of sulfur-mediated electron

  4. 76 FR 56797 - United States v. Cumulus Media Inc., et al.; Proposed Final Judgment and Competitive Impact...

    Science.gov (United States)

    2011-09-14

    ... decline as a result of the transaction. Cumulus must divest: WRSR, WCAT, and the Federal Communications... is required to determine not whether a particular decree is the one that will best serve society, but.... Gillette Co., 406 F. Supp. 713, 716 (D. Mass. 1975) (noting that, in this way, the court is constrained...

  5. Electron transport in acceptor-sensitized polymer-oxide solar cells: the importance of surface dipoles and electron cascade effects.

    Science.gov (United States)

    Berhe, Seare A; Zhou, Joy Y; Haynes, Keith M; Rodriguez, Marco T; Youngblood, W Justin

    2012-06-27

    Fullerene and acenequinone compounds have been examined as electron mediators between a p-type semiconductive polymer and two n-type oxide semiconductors. Composite interlayer materials and photovoltaic test cells were assembled and studied for their fluorescence quenching, current-voltage, and quantum efficiency behavior to characterize the efficacy of the acceptor-sensitizers as electron-selective interlayers. The sensitizers are generally more effective with titanium dioxide than with zinc oxide, due to the difference in magnitude of dipole-induced vacuum level shifts at the respective oxide interfaces. In titanium dioxide-based solar cells, where dipole effects are weak, photovoltage and fill factor increase in a trend that matches the increase in the first reduction potential of the acceptor-sensitizers. Photosensitization of the oxide semiconductor by the acceptor-sensitizers is observed to operate either in parallel with the polymer as an alternate photosensitizer or in series with the polymer in a two-photon process, according to an acceptor-sensitizer's first reduction potential. In zinc oxide-based solar cells, where dipole effects are stronger, the acceptor-sensitizers impaired most devices, which is attributed to an upward shift of the oxide's conduction band edge caused by dipole-induced vacuum level shifts. These results have broad implications for designing electron-selective interlayers and solid-state photocells using sensitized oxide semiconductors.

  6. Conventional and 360 degree electron tomography of a micro-crystalline silicon solar cell

    DEFF Research Database (Denmark)

    Duchamp, Martial; Ramar, Amuthan; Kovács, András

    2011-01-01

    Bright-field (BF) and annular dark-field (ADF) electron tomography in the transmission electron microscope (TEM) are used to characterize elongated porous regions or cracks (simply referred to as cracks thereafter) in micro-crystalline silicon (μc-Si:H) solar cell. The limitations of inferring...

  7. Realization of an Electronic Load for Testing Low Power PEM Fuel Cells

    Directory of Open Access Journals (Sweden)

    Djordje Šaponjić

    2011-06-01

    Full Text Available A realized electronic load system intended for testing and characterization of hydrogen fuel sells is described. The system is based on microcontroller PIC16F877 by applying the concept of virtual instrumentation. The accomplished accuracy of the developed electronic system allows performing efficiently investigations of the electro-chemical phenomena involved in the process of designing hydrogen fuel cells.

  8. Macrophages and mast cells in dystrophic masseter muscle: a light and electron microscopic study

    DEFF Research Database (Denmark)

    Kirkeby, S; Mikkelsen, H

    1988-01-01

    Macrophages and mast cells in masseter muscle from normal and dystrophic mice were studied by light and electron microscopy. Acid phosphatase activity and FITC-dextran were used to identify and describe macrophages. Toluidine blue was used as a marker for mast cells. In dystrophic muscle, the num......Macrophages and mast cells in masseter muscle from normal and dystrophic mice were studied by light and electron microscopy. Acid phosphatase activity and FITC-dextran were used to identify and describe macrophages. Toluidine blue was used as a marker for mast cells. In dystrophic muscle...

  9. An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery

    OpenAIRE

    2007-01-01

    In this paper we present an inexpensive electronic measurement instrumentation developed in our laboratory, to measure and plot the impedance of a loaded fuel cell or battery. Impedance measurements were taken by using the load modulation method. This instrumentation has been developed around a VXI system stand which controls electronic cards. Software under Hpvee® was developed for automatic measurements and the layout of the impedance of the fuel cell on load. The measurement environment, l...

  10. Beam Dynamics in an Electron Lens with the Warp Particle-in-cell Code

    CERN Document Server

    Stancari, Giulio; Redaelli, Stefano

    2014-01-01

    Electron lenses are a mature technique for beam manipulation in colliders and storage rings. In an electron lens, a pulsed, magnetically confined electron beam with a given current-density profile interacts with the circulating beam to obtain the desired effect. Electron lenses were used in the Fermilab Tevatron collider for beam-beam compensation, for abort-gap clearing, and for halo scraping. They will be used in RHIC at BNL for head-on beam-beam compensation, and their application to the Large Hadron Collider for halo control is under development. At Fermilab, electron lenses will be implemented as lattice elements for nonlinear integrable optics. The design of electron lenses requires tools to calculate the kicks and wakefields experienced by the circulating beam. We use the Warp particle-in-cell code to study generation, transport, and evolution of the electron beam. For the first time, a fully 3-dimensional code is used for this purpose.

  11. Inhibitors of zinc-dependent metalloproteases hinder sperm passage through the cumulus oophorus during porcine fertilization in vitro.

    Science.gov (United States)

    Beek, J; Nauwynck, H; Maes, D; Van Soom, A

    2012-12-01

    In this study, we report for the first time on a possible contribution of metalloproteases in sperm passage through the cumulus matrix in pigs. The presence of 20 μM 1,10-phenanthroline (1,10-PHEN), inhibitor of zinc-dependent metalloproteases, strongly inhibited the degree of sperm penetration in cumulus-intact (CI), but not in cumulus-free (CF), porcine oocytes during IVF. The inhibitory effect of 1,10-PHEN was due to the chelation of metal ions as a non-chelating analog (1,7-PHEN) did not affect IVF rates. Furthermore, incubation with 1,10-PHEN did not affect sperm binding to the zona pellucida nor sperm motility, membrane integrity, or acrosomal status. These findings led to the assumption that 1,10-PHEN interacts with a sperm- or cumulus-derived metalloprotease. Metalloproteases are key players in physiological processes involving degradation or remodeling of extracellular matrix. In vivo, their proteolytic activity is regulated by tissue inhibitors of metalloproteases (TIMP1-TIMP4). We tested the effect of TIMP3 on fertilization parameters after porcine IVF. Similar to 1,10-PHEN, TIMP3 inhibited total fertilization rate of CI but not CF oocytes and did not influence sperm quality parameters. Although the inhibitory effect was stronger in CI oocytes, TIMP3 also reduced the degree of sperm penetration in CF oocytes, suggesting the involvement of a metalloprotease in a subsequent step during fertilization. In conclusion, our results indicate the involvement of TIMP3-sensitive, zinc-dependent metalloprotease activity in sperm passage through the cumulus oophorus in pigs. The results should provide the basis for further biochemical research toward the localization and identification of the metalloprotease involved.

  12. Electron migration and stability of dye solar cells

    CSIR Research Space (South Africa)

    Le Roux, Lukas J

    2008-07-01

    Full Text Available on the efficiency of the cells were investigated. Two physical properties of the solvents (viscosity and permittivity) were used in this comparison. Electrochemical impedance spectroscopy (Nyquist and Bode plots) was used for analysis of the charge transfer...

  13. High Energy Electron Radiation Degradation of Gallium Arsenide Solar Cells.

    Science.gov (United States)

    1986-03-01

    relative spectral output of the Kratos source was determined. This procedure may be algebraically verified since the cell output current, i, is equal...A (cm2), then a unique voltage may be calculated for given values of 0 and C. Algebraically , this equation may be written as ~q A 77e ____ __ 8) C...position as necessary to achieve proper voltage. (d) Place solar cell on test block using plastic tweezers. (e) Start test program by typing " BASICA

  14. Pt/Pd electrocatalyst electrons for fuel cells

    Science.gov (United States)

    Stonehart, P.

    1981-11-03

    This invention relates to improved electrochemical cells and to novel electrodes for use therein. In particular, the present invention comprises a fuel cell used primarily for the consumption of impure hydrogen fuels containing carbon monoxide or carbonaceous fuels where the electrode in contact with the fuel is not substantially poisoned by carbon monoxide. The anode of the fuel cell comprises a Pd/Pt alloy supported on a graphitized or partially graphitized carbon material. Fuel cells which comprise as essential elements a fuel electrode, an oxidizing electrode, and an electrolyte between said electrodes are devices for the direct production of electricity through the electrochemical combustion of a fuel and oxidant. These devices are recognized for their high efficiency as energy conversion units, since unlike conventional combustion engines, they are not subject to the limitations of the Carnot heat cycle. It is the primary object of the present invention to provide an electrode having high electrochemical activity for an electrochemical cell. It is another object of the present invention to provide an electrode having an electro-catalyst which is highly resistant to the corrosive environment of an electrochemical cell.

  15. Serial block face scanning electron microscopy--the future of cell ultrastructure imaging.

    Science.gov (United States)

    Hughes, Louise; Hawes, Chris; Monteith, Sandy; Vaughan, Sue

    2014-03-01

    One of the major drawbacks in transmission electron microscopy has been the production of three-dimensional views of cells and tissues. Currently, there is no one suitable 3D microscopy technique that answers all questions and serial block face scanning electron microscopy (SEM) fills the gap between 3D imaging using high-end fluorescence microscopy and the high resolution offered by electron tomography. In this review, we discuss the potential of the serial block face SEM technique for studying the three-dimensional organisation of animal, plant and microbial cells.

  16. A light- and electron microscopic study of primordial germ cells in the zebra fish (Danio rerio).

    Science.gov (United States)

    Deniz Koç, Nazan; Yüce, Rikap

    2012-01-01

    In sexually reproducing organisms, primordial germ cells (PGCs) give rise to the cells of the germ line, the gametes. In many animals, PGCs are set apart from somatic cells early during embryogenesis. This study explores the origin of primordial germ cells (PGCs) of the zebra fish and examines their morphology during early development (1st day-15th day). PGCs were selectively stained by the alkaline phosphatase histochemical reaction and viewed by light and electron microscopy from the time they are first detectable in the yolk sac endoderm. PGCs occurred in the subendodermal space on the syncytial periblast; differing from the surrounding endodermal cells. Later the PGCs moved to between the blastoderm and yolk sac and transferred to the dorsal mesentery where they formed gonadal anlage with mesoderm cells. PGCs were easily distinguished from somatic cells by their morphology and low electron density of their nuclei. Under light microscopy, PCGs were rounded with a distinct cytoplasmic membrane.

  17. Large-eddy simulation of organized precipitating trade wind cumulus clouds

    Directory of Open Access Journals (Sweden)

    A. Seifert

    2013-01-01

    Full Text Available Trade wind cumulus clouds often organize in along-wind cloud streets and across-wind mesoscale arcs. We present a benchmark large-eddy simulation which resolves the individual clouds as well as the mesoscale organization on scales of O(10 km. Different methods to quantify organization of cloud fields are applied and discussed. Using perturbed physics large-eddy simulations experiments the processes leading to the formation of cloud clusters and the mesoscale arcs are revealed. We find that both cold pools as well as the sub-cloud layer moisture field are crucial to understand the organization of precipitating shallow convection. Further sensitivity studies show that microphysical assumptions can have a pronounced impact on the onset of cloud organization.

  18. Grading of Mammalian Cumulus Oocyte Complexes using Machine Learning for in Vitro Embryo Culture

    CERN Document Server

    Sudarshan, Viswanath P; Chintala, Phalgun; Mandal, Subhamoy; Dutta, Rahul

    2016-01-01

    Visual observation of Cumulus Oocyte Complexes provides only limited information about its functional competence, whereas the molecular evaluations methods are cumbersome or costly. Image analysis of mammalian oocytes can provide attractive alternative to address this challenge. However, it is complex, given the huge number of oocytes under inspection and the subjective nature of the features inspected for identification. Supervised machine learning methods like random forest with annotations from expert biologists can make the analysis task standardized and reduces inter-subject variability. We present a semi-automatic framework for predicting the class an oocyte belongs to, based on multi-object parametric segmentation on the acquired microscopic image followed by a feature based classification using random forests.

  19. Parallelization of the NASA Goddard Cumulus Ensemble Model for Massively Parallel Computing

    Directory of Open Access Journals (Sweden)

    Hann-Ming Henry Juang

    2007-01-01

    Full Text Available Massively parallel computing, using a message passing interface (MPI, has been implemented into a three-dimensional version of the Goddard Cumulus Ensemble (GCE model. The implementation uses the domainresemble concept to design a code structure for both the whole domain and sub-domains after decomposition. Instead of inserting a group of MPI related statements into the model routine, these statements are packed into a single routine. In other words, only a single call statement to the model code is utilized once in a place, thus there is minimal impact on the original code. Therefore, the model is easily modified and/or managed by the model developers and/or users, who have little knowledge of massively parallel computing.

  20. Derivation of Cumulus Cloud Dimensions and Shape from the Airborne Measurements by the Research Scanning Polarimeter

    Science.gov (United States)

    Alexandrov, Mikhail D.; Cairns, Brian; Emde, Claudia; Ackerman, Andrew S.; Ottaviani, Matteo; Wasilewski, Andrzej P.

    2016-01-01

    The Research Scanning Polarimeter (RSP) is an airborne instrument, whose measurements have been extensively used for retrievals of microphysical properties of clouds. In this study we show that for cumulus clouds the information content of the RSP data can be extended by adding the macroscopic parameters of the cloud, such as its geometric shape, dimensions, and height above the ground. This extension is possible by virtue of the high angular resolution and high frequency of the RSP measurements, which allow for geometric constraint of the cloud's 2D cross section between a number of tangent lines of view. The retrieval method is tested on realistic 3D radiative transfer simulations and applied to actual RSP data.

  1. Clustering, randomness and regularity in cloud fields. I - Theoretical considerations. II - Cumulus cloud fields

    Science.gov (United States)

    Weger, R. C.; Lee, J.; Zhu, Tianri; Welch, R. M.

    1992-01-01

    The current controversy existing in reference to the regularity vs. clustering in cloud fields is examined by means of analysis and simulation studies based upon nearest-neighbor cumulative distribution statistics. It is shown that the Poisson representation of random point processes is superior to pseudorandom-number-generated models and that pseudorandom-number-generated models bias the observed nearest-neighbor statistics towards regularity. Interpretation of this nearest-neighbor statistics is discussed for many cases of superpositions of clustering, randomness, and regularity. A detailed analysis is carried out of cumulus cloud field spatial distributions based upon Landsat, AVHRR, and Skylab data, showing that, when both large and small clouds are included in the cloud field distributions, the cloud field always has a strong clustering signal.

  2. Pre-Cumulus zoning, Residual Porosity, and Impermeable Barriers in Igneous Cumulates

    Science.gov (United States)

    Morse, S. A.

    2009-12-01

    As Maaløe noted in 1976 the basal Skaergaard cumulates commonly contain plagioclase crystals with zoning and resorption that preceded their accumulation on the floor. This conclusion follows from the observation that neighboring grains are unassociated with each other in their zoning. Such crystals, he reasoned, have been tossed about from cooler to hotter regimes in a way that we might call a hailstone history. By contrast, associated grains zoned from trapped liquid have a common junction, easily signaled in troctolites by a scrap of augite or opaque oxide. In a compilation of the An-range (max - min) in Kiglapait grain mounts, samples sorted by increasing values when examined reveal a dominance of unassociated pre-cumulus grains up to values of 5.5 to 7.5 (median 6.65) mole % in the An range, beyond which increasing evidence for intercumulus growth sets in. The pre-cumulus samples occur among other types in stratigraphic levels from 10 to 83 PCS and include rare samples with cumulus augite. A conservative threshold for intercumulus growth is taken as 6 mole %, above which the An-range minus 6 defines residual porosity p(r) >0 (Morse, AGU JA Abstr. 2009). In the presence of pre-cumulus zoning, the threshold criterion for adcumulus growth rises even higher, for example to An range 8 or even 9 mole %, allowing for the fact that even imperfect adcumulates have had a major amount of isothermal adcumulus growth before or after trapping a small amount of residual liquid. At the conservative end of this range, 75 % of the Kiglapait cumulates are practical adcumulates, 17 % are mesocumulates, and 8% are orthocumulates, the latter dominating both lowermost and highest parts of the stratigraphy. From this intrusion-wide distribution, the overall probability that a given rock sample is an adcumulate is 0.75. But the scarcity of mesocumulates in the LZ above 30 PCS and in the UZ from 95 to 99.9 PCS means that the probability of finding an adcumulate is much greater

  3. Analysis of spatial inhomogeneities in cumulus clouds using high spatial resolution Landsat data

    Science.gov (United States)

    Parker, Lindsay; Welch, R. M.; Musil, D. J.

    1986-01-01

    Aircraft observations and high resolution Landsat MSS digital data are used to determine the sizes of spatial inhomogeneities ('holes') in cumulus clouds. The majority of holes are found near cloud edges, but the larger holes tend to be found in cloud interiors. Aircraft measurements show these cloud spatial inhomogeneities in the range of 100 to 500 m, while Landsat data show them in the range of 100 m to 3 km. The number of holes per cloud decreases exponentially with increasing hole diameter. Small clouds not only have smaller holes, but also fewer holes than large clouds. Large clouds have large holes in them, as well as large numbers of the smaller holes. The total cloud area occupied by holes increases with increasing cloud size.

  4. Derivation of Cumulus Cloud Dimensions and Shape from the Airborne Measurements by the Research Scanning Polarimeter

    Science.gov (United States)

    Alexandrov, Mikhail D.; Cairns, Brian; Emde, Claudia; Ackerman, Andrew S.; Ottaviani, Matteo; Wasilewski, Andrzej P.

    2016-01-01

    The Research Scanning Polarimeter (RSP) is an airborne instrument, whose measurements have been extensively used for retrievals of microphysical properties of clouds. In this study we show that for cumulus clouds the information content of the RSP data can be extended by adding the macroscopic parameters of the cloud, such as its geometric shape, dimensions, and height above the ground. This extension is possible by virtue of the high angular resolution and high frequency of the RSP measurements, which allow for geometric constraint of the cloud's 2D cross section between a number of tangent lines of view. The retrieval method is tested on realistic 3D radiative transfer simulations and applied to actual RSP data.

  5. A long way to the electrode: how do Geobacter cells transport their electrons?

    Science.gov (United States)

    Bonanni, Pablo Sebastián; Schrott, Germán David; Busalmen, Juan Pablo

    2012-12-01

    The mechanism of electron transport in Geobacter sulfurreducens biofilms is a topic under intense study and debate. Although some proteins were found to be essential for current production, the specific role that each one plays in electron transport to the electrode remains to be elucidated and a consensus on the mechanism of electron transport has not been reached. In the present paper, to understand the state of the art in the topic, electron transport from inside of the cell to the electrode in Geobacter sulfurreducens biofilms is analysed, reviewing genetic studies, biofilm conductivity assays and electrochemical and spectro-electrochemical experiments. Furthermore, crucial data still required to achieve a deeper understanding are highlighted.

  6. The nuclear and developmental competence of cumulus-oocyte complexes is enhanced by three-dimensional coculture with conspecific denuded oocytes during in vitro maturation in the domestic cat model.

    Science.gov (United States)

    Morselli, M G; Luvoni, G C; Comizzoli, P

    2017-04-01

    The objective of the study was to assess the efficacy of coculture with conspecific cumulus-denuded oocytes (CDOs) during in vitro maturation in a three-dimensional system of barium alginate microcapsules on the in vitro embryo development of domestic cat cumulus-oocyte complexes (COCs). In Experiment I, COCs were cocultured with conspecific CDOs or cultured separately in a 3D system for 24 hr of in vitro maturation, before assessing the meiotic progression. In Experiment II, the in vitro fertilization of COCs and CDOs was carried out with chilled epididymal spermatozoa and the presumptive zygotes were cultured in vitro separately for 7 days in 3D microcapsules before assesment of embryonic development. The results showed that the viability was maintained and that meiosis was resumed in the 3D culture system. The presence of CDOs during in vitro maturation improved the meiotic competence of the COCs, since the proportions of telophase I/metaphase II were higher than that in the groups cultured separately. The enrichment of the maturation system by companion oocytes also enhanced the ability of COCs to develop into embryos, and increased the percentages of morula and blastoycst stages. The COCs cocultured with CDOs developed at higher rates than the COCs cultured separately and the CDOs themselves. The beneficial effects of coculture with conspecific CDOs were presumably due to the paracrine action of some secreted factors that enhanced many molecular patterns related to the complex of cumulus oophorous cells. Further investigations to understand how the 3D microenvironment can influence the features of oocytes and embryos are required. © 2016 Blackwell Verlag GmbH.

  7. Nano particles play with electrons: Fundamental research into electron transport inside dye-sensitised solar cells

    NARCIS (Netherlands)

    Van Den Berg, R.

    2000-01-01

    Were stuck with a chicken-and-egg-problem: solar cells are expensive, so they dont get sold, which keeps the production volume low, so the price remains high.However, within a decade the price of electricity from a solar panel will be comparable to that of conventional mains power, says Dr. Albert

  8. Nano particles play with electrons: Fundamental research into electron transport inside dye-sensitised solar cells

    NARCIS (Netherlands)

    Van Den Berg, R.

    2000-01-01

    Were stuck with a chicken-and-egg-problem: solar cells are expensive, so they dont get sold, which keeps the production volume low, so the price remains high.However, within a decade the price of electricity from a solar panel will be comparable to that of conventional mains power, says Dr. Albert G

  9. Nano particles play with electrons: Fundamental research into electron transport inside dye-sensitised solar cells

    NARCIS (Netherlands)

    Van Den Berg, R.

    2000-01-01

    Were stuck with a chicken-and-egg-problem: solar cells are expensive, so they dont get sold, which keeps the production volume low, so the price remains high.However, within a decade the price of electricity from a solar panel will be comparable to that of conventional mains power, says Dr. Albert G

  10. Dynamics, thermodynamics, radiation, and cloudiness associated with cumulus-topped marine boundary layers

    Energy Technology Data Exchange (ETDEWEB)

    Ghate, Virendra P. [Argonne National Lab. (ANL), Argonne, IL (United States); Miller, Mark [Rutgers Univ., New Brunswick, NJ (United States)

    2016-11-01

    The overall goal of this project was to improve the understanding of marine boundary clouds by using data collected at the Atmospheric Radiation Measurement (ARM) sites, so that they can be better represented in global climate models (GCMs). Marine boundary clouds are observed regularly over the tropical and subtropical oceans. They are an important element of the Earth’s climate system because they have substantial impact on the radiation budget together with the boundary layer moisture, and energy transports. These clouds also have an impact on large-scale precipitation features like the Inter Tropical Convergence Zone (ITCZ). Because these clouds occur at temporal and spatial scales much smaller than those relevant to GCMs, their effects and the associated processes need to be parameterized in GCM simulations aimed at predicting future climate and energy needs. Specifically, this project’s objectives were to (1) characterize the surface turbulent fluxes, boundary layer thermodynamics, radiation field, and cloudiness associated with cumulus-topped marine boundary layers; (2) explore the similarities and differences in cloudiness and boundary layer conditions observed in the tropical and trade-wind regions; and (3) understand similarities and differences by using a simple bulk boundary layer model. In addition to working toward achieving the project’s three objectives, we also worked on understanding the role played by different forcing mechanisms in maintaining turbulence within cloud-topped boundary layers We focused our research on stratocumulus clouds during the first phase of the project, and cumulus clouds during the rest of the project. Below is a brief description of manuscripts published in peer-reviewed journals that describe results from our analyses.

  11. Entrainment rates at the tops of laboratory analogs of cumulus and stratocumulus clouds

    Science.gov (United States)

    Górska, Anna; Malinowski, Szymon P.; Fugal, Jacob

    2015-04-01

    We investigate entrainment at tops of laboratory analogs of convective clouds: cumulus and stratocumulus. Cloudy saturated moist air (T ~22 °C) containing droplets of diameters of ~3-10 μm, is introduced into a laboratory cloud chamber of dimensions of 1.0×1.0×1.8 through an opening in the bottom wall. Initialy cloudy air fills ~60 cm thick layer at the bottom. Mixing between the cloud and unsaturated air above (T ~22 °C, RH ~35 %) results in evaporative cooling triggering convection which, in turn, leads to formation of a well mixed layer capperd with a temperature inversion. The temperature jump is about 2 °C within ~30 cm deep layer. Then updrafts are forced through a 30cm high tube extending from the bottom of the chamber. "Strong' updrafts which penetrate the whole inversion layer mimic overshooting cumulus clouds while "weak' updrafts diverging under the inversion simulate stratocumulus clouds. We use a laser sheet technique to image two-dimensional cross sections through the clouds. A specially developed mutiscale Particle Image Velicimetry (PIV) algorithm allows to retrieve 2D velocity fields. Suitable image processing allows to determine cloud-clear air interface in the images. Extracting velocities of cloudy (ui) and environmental (ua) air on both sides of the interface allows us calculate entrainment / detrainment rates: E = -ρa(ua - ui) - entrainment rate D = ρa(ua - ui) - detrainment rate. On the poster we will present fine structures of entraimnet/dertaiment process and discuss similarities and differences in both investigated types of clouds.

  12. Improving Forecasts of Cumulus: An Intersection of the Renewable Energy and Climate Science Communities

    Science.gov (United States)

    Berg, L. K.; Gustafson, W. I., Jr.; Kassianov, E.; Long, C. N.

    2015-12-01

    Accurate forecasts of broken cloud fields and their associated impact on the downwelling solar irradiance has remained a challenge to the renewable energy industry. Likewise, shallow cumulus play an important role in the Earth's radiation budget and hydrologic cycle and are of interest to the weather forecasting and climate science communities. The main challenge associated with predicting these clouds are their relatively small size (on the order of a kilometer or less) relative to the model grid spacing. Recently, however, there have been significant efforts put into improving forecasts of shallow clouds and the associated temporal and spatial variability of the solar irradiance that they induce. As an example of these efforts, we will describe recent modifications to the standard Kain-Fritsch parameterization as applied within the Weather Research and Forecasting (WRF) model that are designed to improve predictions of the macroscale and microscale structure of shallow cumulus. These modifications are shown to lead to a realistic increase in the simulated cloud fraction and associated decrease in the solar irradiance. We will evaluate our results using data collected at the Department of Energy's Atmospheric Radiation Measurement (ARM) Southern Great Plains site, which is located in north-central Oklahoma. Our team has analyzed over 5 years of data collected at this site to document the macroscale structure of the clouds (including cloud fraction, cloud-base and cloud-top height) as well as their impact on the downwelling shortwave and longwave irradiance. One particularly interesting impact of shallow cumuli is the enhancement of the diffuse radiation, such that during periods in which the sun is not blocked, the observed irradiance can be significantly larger than the corresponding clear sky case. To date, this feature is not accurately represented by models that apply the plane-parallel assumption applied in the standard radiation parameterizations.

  13. Improving ENSO periodicity simulation by adjusting cumulus entrainment in BCC_CSMs

    Science.gov (United States)

    Lu, Bo; Ren, Hong-Li

    2016-12-01

    The simulation of El Niño-Southern Oscillation (ENSO) phenomenon is a challenging issue for coupled climate models. This study focuses on the ENSO periodicity simulated by Beijing Climate Center Climate System Models (BCC_CSM1.1 and BCC_CSM1.1m) which can reproduce reasonably well ENSO amplitude as observations. However, the major period of ENSO simulated by the BCC_CSMs is around 2.4 years, which is much shorter than that in observations. Compared with other 24 coupled models in Coupled Model Intercomparison Project Phase 5 (CMIP5), BCC_CSMs produce a very unrealistic ENSO peak period. Such a bias in simulating periodicity is suggested as a consequence of the severely underestimated air-sea coupling intensity in BCC_CSMs. To test this hypothesis, a quantitative method is developed to diagnose the linear ENSO frequency. As an effort to improve the ENSO simulation in BCC_CSMs, three experiments are performed with varying entrainment rates in the cumulus convection parameterization scheme of BCC_CSM1.1m. A more realistic ENSO period of about 3.3 years can be generated by the model with an inflated entrainment rate. When the cumulus entrainment is increased by 10%, the ENSO-related convective precipitation will enhance in the equatorial central to eastern Pacific. This anomalous convective heating induces an intensified surface westerly wind stress to the west of the anomalous convection center and as a result, the air-sea coupling intensity becomes larger, which contributes to a longer period of ENSO based on previous theories. In addition, the pronounced eastward extension of ENSO-related surface wind stress could also be the secondary factor to generate a lower frequency of ENSO in BCC_CSMs. Our study proposes a method to reduce the biases in ENSO periodicity simulation and puts more insights into the importance of adjusting atmospheric convection to reproduce ENSO properties in coupled model.

  14. Investigation of Aerosol Indirect Effects using a Cumulus Microphysics Parameterization in a Regional Climate Model

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Kyo-Sun; Fan, Jiwen; Leung, Lai-Yung R.; Ma, Po-Lun; Singh, Balwinder; Zhao, Chun; Zhang, Yang; Zhang, Guang; Song, Xiaoliang

    2014-01-29

    A new Zhang and McFarlane (ZM) cumulus scheme includes a two-moment cloud microphysics parameterization for convective clouds. This allows aerosol effects to be investigated more comprehensively by linking aerosols with microphysical processes in both stratiform clouds that are explicitly resolved and convective clouds that are parameterized in climate models. This new scheme is implemented in the Weather Research and Forecasting (WRF) model, which is coupled with the physics and aerosol packages from the Community Atmospheric Model version 5 (CAM5). A test case of July 2008 during the East Asian summer monsoon is selected to evaluate the performance of the new ZM scheme and to investigate aerosol effects on monsoon precipitation. The precipitation and radiative fluxes simulated by the new ZM scheme show a better agreement with observations compared to simulations with the original ZM scheme that does not include convective cloud microphysics and aerosol convective cloud interactions. Detailed analysis suggests that an increase in detrained cloud water and ice mass by the new ZM scheme is responsible for this improvement. To investigate precipitation response to increased anthropogenic aerosols, a sensitivity experiment is performed that mimics a clean environment by reducing the primary aerosols and anthropogenic emissions to 30% of that used in the control simulation of a polluted environment. The simulated surface precipitation is reduced by 9.8% from clean to polluted environment and the reduction is less significant when microphysics processes are excluded from the cumulus clouds. Ensemble experiments with ten members under each condition (i.e., clean and polluted) indicate similar response of the monsoon precipitation to increasing aerosols.

  15. Direct Numerical Simulation of Evaporative Cooling at the Lateral Boundary of Shallow Cumulus Clouds

    Science.gov (United States)

    Heus, T.; Abma, D.; Mellado, J.

    2012-12-01

    This study investigates the dynamics of a narrow region of subsiding air at the lateral boundary of cumulus clouds, focusing on the role of evaporative cooling. Previous observational and large-eddy simulations showed the relevance of this subsiding shell in cloud dynamics, but have also showed that the size of this shell is well below what large-eddy simulations can resolve. Therefore, we have performed direct numerical simulations of an idealized subsiding shell to investigate accurately the complete turbulent field. The system develops a self-similar, Reynolds number independent flow which allows for the determination of explicit scaling laws relating the characteristic length, time and velocity scales of the shell. In particular, it is found that the shell width grows quadratically in time, and linearly with decreasing height. The magnitude of these growth rates confirm the importance of the subsiding shell because of the relatively fast development of entrainment-determining scales: for typical thermodynamic conditions in cumulus clouds, a velocity of the order of 1~m~s-1 and a thickness of the order of 10 meters are established in about 2 minutes. This fits well within the typical cloud life time, suggesting that our idealization is an adequate framework for the analysis of relevant aspects in the subsiding shell associated with buoyancy reversal. It also indicates that the scaling laws derived here can be used to estimate the potential strength of a subsiding shell and the mean lateral entrainment associated with it, provided an estimate of the local thermodynamical state of the cloud boundary. It is shown that the dominant parameter of this system is the saturation buoyancy, whereas the effect of the saturation mixing fraction is minor.uoyancy field in the subsiding shell. Blue colors are low values, red colors are high values.

  16. Observational estimates of detrainment and entrainment in non-precipitating shallow cumulus

    Science.gov (United States)

    Norgren, M. S.; Small, J. D.; Jonsson, H. H.; Chuang, P. Y.

    2016-01-01

    Vertical transport associated with cumulus clouds is important to the redistribution of gases, particles, and energy, with subsequent consequences for many aspects of the climate system. Previous studies have suggested that detrainment from clouds can be comparable to the updraft mass flux, and thus represents an important contribution to vertical transport. In this study, we describe a new method to deduce the amounts of gross detrainment and entrainment experienced by non-precipitating cumulus clouds using aircraft observations. The method utilizes equations for three conserved variables: cloud mass, total water, and moist static energy. Optimizing these three equations leads to estimates of the mass fractions of adiabatic mixed-layer air, entrained air and detrained air that the sampled cloud has experienced. The method is applied to six flights of the CIRPAS Twin Otter during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) which took place in the Houston, Texas region during the summer of 2006 during which 176 small, non-precipitating cumuli were sampled. Using our novel method, we find that, on average, these clouds were comprised of 30 to 70 % mixed-layer air, with entrained air comprising most of the remainder. The mass fraction of detrained air was usually very small, less than 2 %, although values larger than 10 % were found in 15 % of clouds. Entrained and detrained air mass fractions both increased with altitude, consistent with some previous observational studies. The largest detrainment events were almost all associated with air that was at their level of neutral buoyancy, which has been hypothesized in previous modeling studies. This new method could be readily used with data from other previous aircraft campaigns to expand our understanding of detrainment for a variety of cloud systems.

  17. Graphene-enabled electron microscopy and correlated super-resolution microscopy of wet cells.

    Science.gov (United States)

    Wojcik, Michal; Hauser, Margaret; Li, Wan; Moon, Seonah; Xu, Ke

    2015-06-11

    The application of electron microscopy to hydrated biological samples has been limited by high-vacuum operating conditions. Traditional methods utilize harsh and laborious sample dehydration procedures, often leading to structural artefacts and creating difficulties for correlating results with high-resolution fluorescence microscopy. Here, we utilize graphene, a single-atom-thick carbon meshwork, as the thinnest possible impermeable and conductive membrane to protect animal cells from vacuum, thus enabling high-resolution electron microscopy of wet and untreated whole cells with exceptional ease. Our approach further allows for facile correlative super-resolution and electron microscopy of wet cells directly on the culturing substrate. In particular, individual cytoskeletal actin filaments are resolved in hydrated samples through electron microscopy and well correlated with super-resolution results.

  18. Scanning electron microscopy of cells and tissues under fully hydrated conditions.

    Science.gov (United States)

    Thiberge, Stephan; Nechushtan, Amotz; Sprinzak, David; Gileadi, Opher; Behar, Vered; Zik, Ory; Chowers, Yehuda; Michaeli, Shulamit; Schlessinger, Joseph; Moses, Elisha

    2004-03-09

    A capability for scanning electron microscopy of wet biological specimens is presented. A membrane that is transparent to electrons protects the fully hydrated sample from the vacuum. The result is a hybrid technique combining the ease of use and ability to see into cells of optical microscopy with the higher resolution of electron microscopy. The resolution of low-contrast materials is approximately 100 nm, whereas in high-contrast materials the resolution can reach 10 nm. Standard immunogold techniques and heavy-metal stains can be applied and viewed in the fluid to improve the contrast. Images present a striking combination of whole-cell morphology with a wealth of internal details. A possibility for direct inspection of tissue slices transpires, imaging only the external layer of cells. Simultaneous imaging with photons excited by the electrons incorporates data on material distribution, indicating a potential for multilabeling and specific scintillating markers.

  19. Electron Spin Resonance Study of Fuel Cell Polymer Membrane Degradation

    Institute of Scientific and Technical Information of China (English)

    Alexander Panchenko; Elena Aleksandrova; Emil Roduner

    2005-01-01

    @@ 1Introduction The long term stability of the membrane is an important factor limiting the fuel cell lifetime. During extended use the membrane degrades, probably via reaction with hydroxyl and superoxide radicals which are regular intermediates of the oxygen reduction at the cathode. Only extremely stable membranes can withstand the aggressive chemical and physical environment in an operating fuel cell. Within a given set of operating conditions, intrinsic chemical and mechanical properties of the membrane as well as its water content impact its durability dramatically.

  20. In SITU Transmission Electron Microscopy on Operating Electrochemical CELLS

    DEFF Research Database (Denmark)

    Gualandris, Fabrizio; Simonsen, Søren Bredmose; Mogensen, Mogens Bjerg

    2016-01-01

    Solid oxide cells (SOC) have the potential of playing a significant role in the future efficient energy system scenario. In order to become widely commercially available, an improved performance and durability of the cells has to be achieved [1]. Conventional scanning and transmission SEM and TEM...... have been often used for ex-situ post mortem characterization of SOFCs and SOECs [2,3]. However, in order to get fundamental insight of the microstructural development of SOFC/SOEC during operation conditions in situ studies are necessary [4]....

  1. In SITU Transmission Electron Microscopy on Operating Electrochemical CELLS

    DEFF Research Database (Denmark)

    Gualandris, Fabrizio; Simonsen, Søren Bredmose; Mogensen, Mogens Bjerg

    2016-01-01

    Solid oxide cells (SOC) have the potential of playing a significant role in the future efficient energy system scenario. In order to become widely commercially available, an improved performance and durability of the cells has to be achieved [1]. Conventional scanning and transmission SEM and TEM...... have been often used for ex-situ post mortem characterization of SOFCs and SOECs [2,3]. However, in order to get fundamental insight of the microstructural development of SOFC/SOEC during operation conditions in situ studies are necessary [4]....

  2. High-Resolution Transmission Electron Microscopy Observation of Colloidal Nanocrystal Growth Mechanisms using Graphene Liquid Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yuk, Jong Min; Park, Jungwon; Ercius, Peter; Kim, Kwanpyo; Hellebusch, Danny J.; Crommie, Michael F.; Lee, Jeong Yong; Zettl, A.; Alivisatos, A. Paul

    2011-12-12

    We introduce a new type of liquid cell for in-situ electron microscopy based upon entrapment of a liquid film between layers of graphene. We employ this cell to achieve high-resolution imaging of colloidal platinum nanocrystal growth. The ability to directly image and resolve critical steps at atomic resolution provides new insights into nanocrystal coalescence and reshaping during growth.

  3. Hexaazatrinaphthylene Derivatives: Efficient Electron-Transporting Materials with Tunable Energy Levels for Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Zhao, Dongbing; Zhu, Zonglong; Kuo, Ming-Yu; Chueh, Chu-Chen; Jen, Alex K-Y

    2016-07-25

    Hexaazatrinaphthylene (HATNA) derivatives have been successfully shown to function as efficient electron-transporting materials (ETMs) for perovskite solar cells (PVSCs). The cells demonstrate a superior power conversion efficiency (PCE) of 17.6 % with negligible hysteresis. This study provides one of the first nonfullerene small-molecule-based ETMs for high-performance p-i-n PVSCs.

  4. Micro-Fuel Cells{sup TM} for portable electronics

    Energy Technology Data Exchange (ETDEWEB)

    Hockaday, R.G.; DeJohn, M.; Navas, C.; Turner, P.S.; Vaz, H.L.; Vazul, L.L. [Energy Related Devices Inc., Los Alamos, NM (United States)

    2000-05-01

    The Micro-Fuel Cell{sup TM} is a new power supply which provides a superior alternative compared to rechargeable batteries. A prototype has been developed by Manhattan Scientifics Inc. in collaboration with Energy Related Devices Inc. This mass-producible high-energy power supply can be used for cellular telephones, portable computers and other portable devices. Instead of being recharged, it can be easily refueled with methanol. The approach taken in designing this product was to develop a competitive product with definite advantages over existing products. The Micro-Fuel Cell{sup TM} is based on the idea that a fuel cell can be built onto an engineered microplastic substrate. In this case, the integrated design makes use of thin film vacuum deposition techniques to coat patterned, etched-nuclear-particle-track plastic membranes. This process forms catalytically active surface area electrodes on either side of a single structured proton-exchange-membrane electrolyte. Methanol was the choice fuel for this system because compared to hydrogen and metal hydrides, it was considered to be safer and more compact. In addition, the theoretical specific energy of methanol is significantly higher than for lithium-ion batteries. The problem of crossover, whereby methanol fuel diffuses across the fuel cell from the anode to the cathode, has also been solved by using a selectively permeable membrane. 5 refs., 4 figs.

  5. Electron trapping in higher adduct fullerene-based solar cells

    NARCIS (Netherlands)

    Lenes, M.; Shelton, S.W.; Sieval, A.B.; Kronholm, D.F.; Hummelen, J.C.; Blom, P.W.M.

    2009-01-01

    Here, the performance of bulk-heterojunction solar cells based on a series of bisadduct analogues of commonly used derivatives of C60 and C 70, such PCBMs and theirthienyl versions, is investigated. Dueto their higher lowest unoccupied molecular orbital an increase in open-circuit voltage and thus p

  6. Increased electron photoemission from plasmonic nanoparticles and photoemission enhanced solar cells

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Uskov, Alexander; Gritti, Claudia;

    2011-01-01

    Numerical simulation shows possibility to enhance substantially (by one-two orders) the electron photoemission through surface of metal nanoparticles embedded into photovoltaic structures. This, in turn, can lead to increase of the solar cells efficiency due to efficient light-to-electricity tran......Numerical simulation shows possibility to enhance substantially (by one-two orders) the electron photoemission through surface of metal nanoparticles embedded into photovoltaic structures. This, in turn, can lead to increase of the solar cells efficiency due to efficient light......-to-electricity transformation below the solar cell semiconductor bandgap....

  7. A study on the key factors affecting the electronic properties of monocrystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ji-cheng; CHEN Yong-min; LI Li; LI Fei; ZHAO Bao-xing

    2009-01-01

    The model of monocrystalline silicon solar cells is established, and the effects of wafer parameters, such as the p-Si (100) substrate thickness, the defect density, and the doping concentration, on the electronic properties of monocrystalline silicon solar cells are analyzed. The results indicate that the solar cells with an A1 back-surface-field will have good electronic properties when the wafers meet the following three conditions: (i) the defect density is less than 1.0×1011 cm-3; (ii) the substrate thickness is in the range of 100 μm to 200 μm.

  8. Revealing 3D Ultrastructure and Morphology of Stem Cell Spheroids by Electron Microscopy.

    Science.gov (United States)

    Jaros, Josef; Petrov, Michal; Tesarova, Marketa; Hampl, Ales

    2017-01-01

    Cell culture methods have been developed in efforts to produce biologically relevant systems for developmental and disease modeling, and appropriate analytical tools are essential. Knowledge of ultrastructural characteristics represents the basis to reveal in situ the cellular morphology, cell-cell interactions, organelle distribution, niches in which cells reside, and many more. The traditional method for 3D visualization of ultrastructural components, serial sectioning using transmission electron microscopy (TEM), is very labor-intensive due to contentious TEM slice preparation and subsequent image processing of the whole collection. In this chapter, we present serial block-face scanning electron microscopy, together with complex methodology for spheroid formation, contrasting of cellular compartments, image processing, and 3D visualization. The described technique is effective for detailed morphological analysis of stem cell spheroids, organoids, as well as organotypic cell cultures.

  9. Non-primitive rectangular cells for tight-binding electronic structure calculations

    OpenAIRE

    Boykin, Timothy; Kharche, Neerav; Klimeck, Gerhard

    2009-01-01

    Rectangular non-primitive unit cells are computationally convenient for use in nanodevice electronic structure and transport calculations. When these cells are used for Calculations of structures with periodicity, the resulting bands are zone-folded and must be unfolded in order to identify important gaps and masses. Before the zone-unfolding method can be applied, one must first determine the allowed wavevectors for the specific non-primitive cell. Because most computationally convenient non...

  10. Non-Primitive Rectangular Cells for Tight-Binding Electronic Structure Calculations

    OpenAIRE

    Boykin, Timothy B.

    2008-01-01

    Rectangular non-primitive unit cells are computationally convenient for use in nanodevice electronic structure and transport calculations. When these cells are used for calculations of structures with periodicity, the resulting bands are zone-folded and must be unfolded in order to identify important gaps and masses. Before the zone-unfolding method can be applied, one must first determine the allowed wavevectors for the specific non-primitive cell. Because most computationally convenient ...

  11. Analysis of Vero cell growth behavior on microcarrier by means of environmental scanning electron microscopy

    Institute of Scientific and Technical Information of China (English)

    SHAO; Manjun(邵曼君); JIANG; Lei(姜蕾); CONG; Wei(丛威); OUYANG; Fan(欧阳藩)

    2002-01-01

    By using environmental scanning electron microscopy, the morphological changes of Vero cells attached to and grown on the microcarrier Cytodex-3 were observed, and their behavior of adhesion, spreading and proliferation was analyzed. The effect of exogenous fibronectin/ laminin on adhesion and spreading of MCC/Vero cell was studied. The images of ESEM showed that expansion of cell growth was directed toward vacancy space. The growth curve and cell concentration change during the whole culture process were obtained from the statistical counting method based on ESEM images and the crystal violet method. The growth rate of Vero cells increases with increasing the concentration of cell inoculation, that is, the specific growth rate increases quickly with increasing the concentration of cell inoculation. When serum concentration in medium #199 ranged from 5% to 10%, experimental results indicated that serum concentration is one of the important factors influencing cell growth, particularly in the cell adhesion and spreading stage.

  12. Electron Microscopy to Correlate Cell Structure and Biochemical Activity

    Science.gov (United States)

    1993-03-10

    Plasmodium coatneyi-infected rhesus monkeys: a primate model for human cerebral malaria. Memorias do Instituto Osvald Cruz (In Press). 24. Sim, K.L...P. coatney1 and found th.’t cvtoadherence of PRBC to ei.dothelial cells is a consistent feature of infections with this primate parasite. Cerebral ...Malaria; iaraunoe loct ror.-micros.’opy ; Chemotherapy; DFO; Cerebral malaria; HA 1 17 SECURITY CLASSIFICATION Of REPORT Unclass1 fled 1

  13. Electronic Interfacing Between a Living Cell and a Nanodevice: A Bio-Nano Hybrid System

    Energy Technology Data Exchange (ETDEWEB)

    Saraf, Ravi F. [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Chemical and Biomolecular Engineering

    2013-12-31

    The primary goal of this program was to couple physical electronics with live cells to leverage the highly sophisticated functions of a biological system to ultimately create advanced functionality. The study was built on a unique self-assembled architecture of nanoparticles that exhibits transport properties that are sensitive to single-electron charge modulation. At room temperature, the energy of switching due to single-electron charge modulation was in the range of 4 to 100 kT. The structure invented in the principal investigator’s lab is a two-dimensional (2D) network of one-dimensional (1D) necklaces of 10 nm Au nanoparticles. The electron transport through the necklace network is regulated by quantum mechanical single-electron traps. As a result of the single electron traps, the all metal nanoparticle network array displays a conduction band gap. Fundamental studies on the transport properties of the network in air and water were studied to regulate the band gap by tailoring the network structure to demonstrate the first electrochemical single electron transistor operating in water. Cells were interfaced with the network to observe electrochemical activity in a cell during photosynthesis and single viral infection.

  14. Electron Transfer Dynamics in Efficient Molecular Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Ke [Johns Hopkins Univ., Baltimore, MD (United States); Ward, William [Johns Hopkins Univ., Baltimore, MD (United States); Farnum, Byron H. [Johns Hopkins Univ., Baltimore, MD (United States); Taheri, Atefeh [Johns Hopkins Univ., Baltimore, MD (United States); Johansson, Patrik [Johns Hopkins Univ., Baltimore, MD (United States); Meyer, Gerald John [Johns Hopkins Univ., Baltimore, MD (United States)

    2014-10-01

    This research provided new mechanistic insights into surface mediated photochemical processes relevant to solar energy conversion. In this past three years our research has focused on oxidation photo-redox chemistry and on the role surface electric fields play on basic spectroscopic properties of molecular-semiconductor interfaces. Although this research as purely fundamental science, the results and their interpretation have relevance to applications in dye sensitized and photogalvanic solar cells as well as in the storage of solar energy in the form of chemical bonds.

  15. Correlation of live-cell imaging with volume scanning electron microscopy.

    Science.gov (United States)

    Lucas, Miriam S; Günthert, Maja; Bittermann, Anne Greet; de Marco, Alex; Wepf, Roger

    2017-01-01

    Live-cell imaging is one of the most widely applied methods in live science. Here we describe two setups for live-cell imaging, which can easily be combined with volume SEM for correlative studies. The first procedure applies cell culture dishes with a gridded glass support, which can be used for any light microscopy modality. The second approach is a flow-chamber setup based on Ibidi μ-slides. Both live-cell imaging strategies can be followed up with serial blockface- or focused ion beam-scanning electron microscopy. Two types of resin embedding after heavy metal staining and dehydration are presented making best use of the particular advantages of each imaging modality: classical en-bloc embedding and thin-layer plastification. The latter can be used only for focused ion beam-scanning electron microscopy, but is advantageous for studying cell-interactions with specific substrates, or when the substrate cannot be removed. En-bloc embedding has diverse applications and can be applied for both described volume scanning electron microscopy techniques. Finally, strategies for relocating the cell of interest are discussed for both embedding approaches and in respect to the applied light and scanning electron microscopy methods. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Sites of inhibition of mitochondrial electron transport in macrophage-injured neoplastic cells.

    Science.gov (United States)

    Granger, D L; Lehninger, A L

    1982-11-01

    Previous work has shown that injury of neoplastic cells by cytotoxic macrophages (CM) in cell culture is accompanied by inhibition of mitochondrial respiration. We have investigated the nature of this inhibition by studying mitochondrial respiration in CM-injured leukemia L1210 cells permeabilized with digitonin. CM-induced injury affects the mitochondrial respiratory chain proper. Complex I (NADH-coenzyme Q reductase) and complex II (succinate-coenzyme Q reductase) are markedly inhibited. In addition a minor inhibition of cytochrome oxidase was found. Electron transport from alpha-glycerophosphate through the respiratory chain to oxygen is unaffected and permeabilized CM-injured L1210 cells oxidizing this substrate exhibit acceptor control. However, glycerophosphate shuttle activity was found not to occur within CM-injured or uninjured L1210 cells in culture hence, alpha-glycerophosphate is apparently unavailable for mitochondrial oxidation in the intact cell. It is concluded that the failure of respiration of intact neoplastic cells injured by CM is caused by the nearly complete inhibition of complexes I and II of the mitochondrial electron transport chain. The time courses of CM-induced electron transport inhibition and arrest of L1210 cell division are examined and the possible relationship between these phenomena is discussed.

  17. Nanostructured Electron-Selective Interlayer for Efficient Inverted Organic Solar Cells.

    Science.gov (United States)

    Song, Jiyun; Lim, Jaehoon; Lee, Donggu; Thambidurai, M; Kim, Jun Young; Park, Myeongjin; Song, Hyung-Jun; Lee, Seonghoon; Char, Kookheon; Lee, Changhee

    2015-08-26

    We report a unique nanostructured electron-selective interlayer comprising of In-doped ZnO (ZnO:In) and vertically aligned CdSe tetrapods (TPs) for inverted polymer:fullerene bulkheterojunction (BHJ) solar cells. With dimension-controlled CdSe TPs, the direct inorganic electron transport pathway is provided, resulting in the improvement of the short circuit current and fill factor of devices. We demonstrate that the enhancement is attributed to the roles of CdSe TPs that reduce the recombination losses between the active layer and buffer layer, improve the hole-blocking as well as electron-transporting properties, and simultaneously improve charge collection characteristics. As a result, the power conversion efficiency of PTB7:PC70BM based solar cell with nanostructured CdSe TPs increases to 7.55%. We expect this approach can be extended to a general platform for improving charge extraction in organic solar cells.

  18. Tandem-structured, hot electron based photovoltaic cell with double Schottky barriers.

    Science.gov (United States)

    Lee, Young Keun; Lee, Hyosun; Park, Jeong Young

    2014-04-03

    We demonstrate a tandem-structured, hot electron based photovoltaic cell with double Schottky barriers. The tandem-structured, hot electron based photovoltaic cell is composed of two metal/semiconductor interfaces. Two types of tandem cells were fabricated using TiO2/Au/Si and TiO2/Au/TiO2, and photocurrent enhancement was detected. The double Schottky barriers lead to an additional pathway for harvesting hot electrons, which is enhanced through multiple reflections between the two barriers with different energy ranges. In addition, light absorption is improved by the band-to-band excitation of both semiconductors with different band gaps. Short-circuit current and energy conversion efficiency of the tandem-structured TiO2/Au/Si increased by 86% and 70%, respectively, compared with Au/Si metal/semiconductor nanodiodes, showing an overall solar energy conversion efficiency of 5.3%.

  19. Subcellular localization of Cd in the root cells of Allium sativum by electron energy loss spectroscopy

    Indian Academy of Sciences (India)

    Donghua Liu; Ingrid Kottke

    2003-06-01

    The ultrastructural investigation of the root cells of Allium sativum L. exposed to three different concentrations of Cd (100 M, 1 mM and 10 mM) for 9 days was carried out. The results showed that Cd induced several significant ultrastructural changes – high vacuolization in cytoplasm, deposition of electron-dense material in vacuoles and nucleoli and increment of disintegrated organelles. Data from electron energy loss spectroscopy (EELS) revealed that Cd was localized in the electron-dense precipitates in the root cells treated with 10 mM Cd. High amounts of Cd were mainly accumulated in the vacuoles and nucleoli of cortical cells in differentiating and mature root tissues. The mechanisms of detoxification and tolerance of Cd are briefly explained.

  20. Numerical Simulations of the 1 May 2012 Deep Convection Event over Cuba: Sensitivity to Cumulus and Microphysical Schemes in a High-Resolution Model

    Directory of Open Access Journals (Sweden)

    Yandy G. Mayor

    2015-01-01

    Full Text Available This paper evaluates the sensitivity to cumulus and microphysics schemes, as represented in numerical simulations of the Weather Research and Forecasting model, in characterizing a deep convection event over the Cuban island on 1 May 2012. To this end, 30 experiments combining five cumulus and six microphysics schemes, in addition to two experiments in which the cumulus parameterization was turned off, are tested in order to choose the combination that represents the event precipitation more accurately. ERA Interim is used as lateral boundary condition data for the downscaling procedure. Results show that convective schemes are more important than microphysics schemes for determining the precipitation areas within a high-resolution domain simulation. Also, while one cumulus scheme captures the overall spatial convective structure of the event more accurately than others, it fails to capture the precipitation intensity. This apparent discrepancy leads to sensitivity related to the verification method used to rank the scheme combinations. This sensitivity is also observed in a comparison between parameterized and explicit cumulus formation when the Kain-Fritsch scheme was used. A loss of added value is also found when the Grell-Freitas cumulus scheme was activated at 1 km grid spacing.

  1. Enhancing electron collection efficiency and effective diffusion length in dye-sensitized solar cells.

    Science.gov (United States)

    Wong, Daniel Kwan-Pang; Ku, Chen-Hao; Chen, Yen-Ru; Chen, Guan-Ren; Wu, Jih-Jen

    2009-10-19

    Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy are employed to measure the dynamics of electron transport and recombination in the ZnO nanowire (NW) array-ZnO/layered basic zinc acetate (LBZA) nanoparticle (NP) composite dye-sensitized solar cells (DSSCs). The roles of the vertical ZnO NWs and insulating LBZA in the electron collection and transport in DSSCs are investigated by comparing the results to those in the TiO(2)-NP, horizontal TiO(2)-NW and vertical ZnO-NW-array DSSCs. The electron transport rate and electron lifetime in the ZnO NW/NP composite DSSC are superior to those in the conventional TiO(2)-NP cell due to the existence of the vertical ZnO NWs and insulating LBZA. It indicates that the ZnO NW/NP composite anode is able to sustain efficient electron collection over much greater thickness than the TiO(2)-NP cell does. Consequently, a larger effective electron diffusion length is available in the ZnO composite DSSC.

  2. Particle-in-cell Simulations of Electron and Ion Dissipation by Whistler Turbulence: Variations with Electron β

    Science.gov (United States)

    Hughes, R. Scott; Gary, S. Peter; Wang, Joseph

    2017-01-01

    Two ensembles of three-dimensional particle-in-cell (PIC) simulations of the forward cascade of decaying whistler turbulence have been carried out on a model of collisionless, homogeneous, magnetized plasma with parameters similar to those of the solar wind near Earth. Initial, relatively isotropic, narrowband spectra of relatively long wavelength modes cascade to anisotropic, broadband spectra of magnetic fluctuations at shorter wavelengths. Electron and ion dissipation rates are computed as functions of the initial electron beta, βe, over the range 0.1 ≤ βe ≤ 5.0, where this quantity is varied by changes in the background magnetic field magnitude Bo. Ensemble One holds the value of the dimensionless initial magnetic fluctuation energy density ɛo ≡ Σk | δ {B}{{k}}{| }2/{B}{{o}}2 constant; Ensemble Two follows solar wind observations, imposing the initial condition ɛo = 0.20 βe. In both ensembles, the maximum dissipation rate of the electrons, Qe, and the maximum dissipation rate of the ions, Qi, satisfy Qe ≫ Qi. In Ensemble One, both dissipation rates scale approximately as {β }{{e}}-1, whereas over 0.1 ≤ βe ≤ 1.0 in Ensemble Two, Qe is approximately constant while Qi scales approximately as {β }{{e}}1/2. These results, when combined with conclusions from earlier PIC simulations, suggest that sufficiently long wavelength and sufficiently large-amplitude magnetosonic-whistler turbulence at sufficiently large βe may heat ions more rapidly than electrons.

  3. Effects of electron radiation on shielded space triple-junction GaAs solar cells

    Institute of Scientific and Technical Information of China (English)

    Gao Xin; Yang Sheng-Sheng; Xue Yu-Xiong; Li Kai; Li Dan-Ming; Wang Yi; Wang Yun-Fei; Feng Zhan-Zu

    2009-01-01

    The displacement damage dose methodology for analysing and modelling the performance of triple-junction InGaP_2/GaAs/Ge solar cells in an electron radiation environment is presented. Degradations at different electron energies are correlated with displacement damage dose (D_d). One particular electron radiation environment, relative to a geosynchronous earth orbit (GEO), is chosen to calculate the total D_d behind the different thicknesses coverglasses to predict the performance degradation at the end of the 15-year mission.

  4. Characterization of biofumigated Ralstonia solanacearum cells using micro-Raman spectroscopy and electron microscopy.

    Science.gov (United States)

    Paret, Mathews L; Sharma, Shiv K; Alvarez, Anne M

    2012-01-01

    Essential oils of palmarosa, lemongrass, and eucalyptus have shown promise as biofumigants for control of the bacterial wilt disease of edible ginger (Zingiber officinale) caused by Ralstonia solanacearum race 4 in previous potting medium studies. Biochemical changes in R. solanacearum cells were evaluated with micro-Raman spectroscopy following treatment with essential oils at different concentrations (0.04, 0.07, and 0.14% [vol/vol] of culture medium) and changes in cell structure were observed using electron microscopy. All treatments except palmarosa oil at 0.04% caused significant reductions in levels of amino acids, purine and pyrimidine bases of nucleic acids, carbohydrates, and lipids, as indicated by significant reduction in Raman peak heights at 621, 1,003, and 1,031 inverse centimeters (cm(-1)) (phenylalanine); 643, 827, 852, 1,158, and 1,172 cm(-1) (tyrosine); 758 cm(-1) (tryptophan); 725, 782, 1,337, and 1,578 cm(-1) (adenine, cytosine plus uracil, adenine, and adenine plus guanine, respectively); 1,097 cm(-1) (carbohydrates); and 1,127, 1,450, and 2,932 cm(-1) (lipids) compared with untreated controls. Lemongrass oil treatments were the most effective in degrading cellular components. Scanning electron microscopy of palmarosa and lemongrass-oil-treated cells showed rupture of cell walls and cell debris but no degradation was noted for eucalyptus-oil-treated cells. Palmarosa- and lemongrass-oil-treated cells were positively stained with uranyl acetate when viewed by transmission electron microscopy whereas controls and eucalyptus-oil-treated cells were negatively stained, indicating that the cell membranes were intact. The viability of eucalyptus-oil-treated cells was confirmed by cell culture following treatment. Micro-Raman spectroscopy is a powerful tool which can be further employed to better understand effects of fumigants and other bactericides on bacterial cells.

  5. A pre-in vitro maturation medium containing cumulus oocyte complex ligand-receptor signaling molecules maintains meiotic arrest, supports the cumulus oocyte complex and improves oocyte developmental competence.

    Science.gov (United States)

    Santiquet, Nicolas W; Greene, Alison F; Becker, John; Barfield, Jennifer P; Schoolcraft, William B; Krisher, Rebecca L

    2017-09-01

    Can a pre-in vitro maturation (pre-IVM) medium containing signaling molecules rather than chemical/pharmaceutical agents, sustain meiotic arrest and improve developmental competence of in vitro matured oocytes in CF1 outbred mice? A short 2 h period of pre-IVM prevents spontaneous meiotic resumption, improves mitochondria activity in subsequently matured oocytes, and increases developmental competence, pregnancy rate and implantation of resulting embryos. Spontaneous resumption of meiosis in vitro is detrimental for oocyte developmental competence. Pre-IVM systems that prevent spontaneous meiotic resumption with chemical/pharmaceutical agents are a promising approach to improving IVM oocyte competence; however, the success of these methods has proven to be inconsistent. This study consisted of a series of experiments using cumulus oocyte complexes (COC) derived from outbred mice following ovarian stimulation. The study was designed to examine if a novel, ligand/receptor-based pre-IVM treatment could sustain meiotic arrest in vitro and improve oocyte developmental competence, compared to control IVM. Two pre-IVM durations (2 h and 24 h) were evaluated, and the effect of the mitochondrial stimulator PQQ during 24 h pre-IVM was studied. Murine (outbred CF1) immature COC were cultured in vitro in the presence of C-type natriuretic peptide (CNP) (30 nM), estradiol (100 nM), FSH (1 × 10-4 IU/ml) and bone morphogenic protein 15 (BMP15) (100 ng/ml) for 2 h or 24 h prior to IVM. Meiotic status during pre-IVM and IVM was analyzed using orcein staining, and functionality of gap junction communication was confirmed using the functional gap junction inhibitor carbenoxolone (CBX). Oocytes exposed to pre-IVM treatment were compared to control oocytes collected on the same day from the same females and undergoing standard IVM. Developmental competence and embryo viability was assessed by oocyte mitochondrial activity and ATP concentration, in vitro embryo development following

  6. The Effect of Cumulus Cloud Field Anisotropy on Domain-Averaged Solar Fluxes and Atmospheric Heating Rates

    Science.gov (United States)

    Hinkelman, Laura M.; Evans, K. Franklin; Clothiaux, Eugene E.; Ackerman, Thomas P.; Stackhouse, Paul W., Jr.

    2006-01-01

    Cumulus clouds can become tilted or elongated in the presence of wind shear. Nevertheless, most studies of the interaction of cumulus clouds and radiation have assumed these clouds to be isotropic. This paper describes an investigation of the effect of fair-weather cumulus cloud field anisotropy on domain-averaged solar fluxes and atmospheric heating rate profiles. A stochastic field generation algorithm was used to produce twenty three-dimensional liquid water content fields based on the statistical properties of cloud scenes from a large eddy simulation. Progressively greater degrees of x-z plane tilting and horizontal stretching were imposed on each of these scenes, so that an ensemble of scenes was produced for each level of distortion. The resulting scenes were used as input to a three-dimensional Monte Carlo radiative transfer model. Domain-average transmission, reflection, and absorption of broadband solar radiation were computed for each scene along with the average heating rate profile. Both tilt and horizontal stretching were found to significantly affect calculated fluxes, with the amount and sign of flux differences depending strongly on sun position relative to cloud distortion geometry. The mechanisms by which anisotropy interacts with solar fluxes were investigated by comparisons to independent pixel approximation and tilted independent pixel approximation computations for the same scenes. Cumulus anisotropy was found to most strongly impact solar radiative transfer by changing the effective cloud fraction, i.e., the cloud fraction when the field is projected on a surface perpendicular to the direction of the incident solar beam.

  7. Electron-collecting oxide layers in inverted polymer solar cells via oxidation of thermally evaporated titanium

    Science.gov (United States)

    Zampetti, A.; Salamandra, L.; Brunetti, F.; Reale, A.; Di Carlo, A.; Brown, T. M.

    2016-10-01

    A simple and intuitive deposition technique is discussed to obtain titanium oxide used as an electron collecting layer in polymer solar cells based on the thermal evaporation of pristine titanium and further thermal treatment to convert the metal in oxide. Since the degradation of indium-doped tin oxide at high temperatures is an issue, we demonstrate that the combination of glass/fluorine tin oxide and high temperatures represents a promising approach in the fabrication of inverted polymer solar cells with such a titanium oxide electron collecting layer.

  8. Diarylindenotetracenes via a selective cross-coupling/C-H functionalization: electron donors for organic photovoltaic cells.

    Science.gov (United States)

    Gu, Xingxian; Luhman, Wade A; Yagodkin, Elisey; Holmes, Russell J; Douglas, Christopher J

    2012-03-16

    A direct synthesis of new donor materials for organic photovoltaic cells is reported. Diaryindenotetracenes were synthesized utilizing a Kumada-Tamao-Corriu cross-coupling of peri-substituted tetrachlorotetracene with spontaneous indene annulation via C-H activation. Vacuum deposited planar heterojunction organic photovoltaic cells incorporating these molecules as electron donors exhibit power conversion efficiencies exceeding 1.5% with open-circuit voltages ranging from 0.7 to 1.1 V when coupled with C(60) as an electron acceptor.

  9. Radiotoxicity induced by Auger electron emitters in human osteosarcoma cell line using comet assay

    Institute of Scientific and Technical Information of China (English)

    XU Yu-Jie; LI Qing-Nuan; ZHU Ran; ZHU Ben-Xing; ZHANG Yong-Ping; ZHANG Xiao-Dong; FAN Wo; HONG Cheng-Jiao; LI Wen-Xin

    2003-01-01

    The comet assay (single cell gel electrophoresis assay) was used to evaluate the radiotoxicity of Augerelectron emitters in the human osteosarcoma cell line (HOS-8603). After internal exposure to 67Ga-EDTMP, the sar-coma cell has been injured severely. The comet length was longer along with the increase of dose, the appearance ofcomet tail was different from that with respect to the 60Co γ-ray irradiation. DNA damage of cell was mainly due tothe radiation effect of Auger electrons. The 67Ga may be a therapeutic radionuclide with good prospect for tumortreatment and palliation of bone pain induced by metastasis.

  10. Intercomparison and evaluation of cumulus parametrizations under summertime midlatitude continental conditions

    Science.gov (United States)

    Xie, Shaocheng; Xu, Kuan-Man; Cederwall, Richard T.; Bechtold, Peter; del Genio, Anthony D.; Klein, Stephen A.; Cripe, Douglas G.; Ghan, Steven J.; Gregory, David; Iacobellis, Sam F.; Krueger, Steven K.; Lohmann, Ulrike; Petch, Jon C.; Randall, David A.; Rotstayn, Leon D.; Somerville, Richard C. J.; Sud, Yogesh C.; von Salzen, Knut; Walker, Gregory K.; Wolf, Audrey; Yio, J. John; Zhang, Guang Jun; Zhang, Minghua

    2002-04-01

    This study reports the Single-Column Model (SCM) part of the Atmospheric Radiation Measurement (ARM)/the Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) joint SCM and Cloud-Resolving Model (CRM) Case 3 intercomparison study, with a focus on evaluation of cumulus parametrizations used in SCMs. Fifteen SCMs are evaluated under summertime midlatitude continental conditions using data collected at the ARM Southern Great Plains site during the summer 1997 Intensive Observing Period. Results from ten CRMs are also used to diagnose problems in the SCMs. It is shown that most SCMs can generally capture well the convective events that were well-developed within the SCM domain, while most of them have difficulties in simulating the occurrence of those convective events that only occurred within a small part of the domain. All models significantly underestimate the surface stratiform precipitation. A third of them produce large errors in surface precipitation and thermodynamic structures. Deficiencies in convective triggering mechanisms are thought to be one of the major reasons. Using a triggering mechanism that is based on the vertical integral of parcel buoyant energy without additional appropriate constraints results in overactive convection, which in turn leads to large systematic warm/dry biases in the troposphere. It is also shown that a non-penetrative convection scheme can underestimate the depth of instability for midlatitude convection, which leads to large systematic cold/moist biases in the troposphere. SCMs agree well quantitatively with CRMs in the updraught mass fluxes, while most models significantly underestimate the downdraught mass fluxes. Neglect of mesoscale updraught and downdraught mass fluxes in the SCMs contributes considerably to the discrepancies between the SCMs and the CRMs. In addition, uncertainties in the diagnosed mass fluxes in the CRMs and deficiencies with cumulus parametrizations are not negligible. Similar

  11. Intensive radiosonde measurements of summertime convection over the Inner Mongolia grassland in 2014: Difference between shallow cumulus and other conditions

    Science.gov (United States)

    Shi, Hongrong; Chen, Hongbin; Xia, Xiang'ao; Fan, Xuehua; Zhang, Jinqiang; Li, Jun; Ling, Chao

    2017-06-01

    Using radiosonde measurements from 26 July to 30 July 2014 at Baiqi over the Inner Mongolia grassland of China, the vertical structure of shallow cumulus (SCu) clouds and associated environmental conditions were investigated. The cloud base height and the cloud top height of SCu was 3.4 km and 5 km, respectively. The temperature of the SCu layer was less than 0°C. The horizontal advection of specific humidity was smaller than the vertical transport in the atmosphere below 5 km. Above 5 km, the thermodynamic structure of the atmosphere remained stable. At the interface of the cloud layer and free air atmosphere, there was obvious wind shear and a temperature inversion ( 2.9°C). Comparisons of environmental parameters associated with cumulus congestus, rain and clear days, showed that the formation of SCu was characterized by a higher Bowen ratio (high sensible heat flux and low latent heat flux), which indicated intensive turbulence in the boundary layer. The formation of SCu was associated with the boundary layer height exceeding the lifting condensation level. The maintenance of SCu was likely associated with the lower convective available potential energy, weak wind shear, and weak subsidence of the synoptic system, which did not favor the dramatic vertical development of SCu and thereby the transformation of SCu to cumulus congestus.

  12. Biguanides sensitize leukemia cells to ABT-737-induced apoptosis by inhibiting mitochondrial electron transport

    Science.gov (United States)

    Velez, Juliana; Pan, Rongqing; Lee, Jason T.C.; Enciso, Leonardo; Suarez, Marta; Duque, Jorge Eduardo; Jaramillo, Daniel; Lopez, Catalina; Morales, Ludis; Bornmann, William; Konopleva, Marina; Krystal, Gerald; Andreeff, Michael; Samudio, Ismael

    2016-01-01

    Metformin displays antileukemic effects partly due to activation of AMPK and subsequent inhibition of mTOR signaling. Nevertheless, Metformin also inhibits mitochondrial electron transport at complex I in an AMPK-independent manner, Here we report that Metformin and rotenone inhibit mitochondrial electron transport and increase triglyceride levels in leukemia cell lines, suggesting impairment of fatty acid oxidation (FAO). We also report that, like other FAO inhibitors, both agents and the related biguanide, Phenformin, increase sensitivity to apoptosis induction by the bcl-2 inhibitor ABT-737 supporting the notion that electron transport antagonizes activation of the intrinsic apoptosis pathway in leukemia cells. Both biguanides and rotenone induce superoxide generation in leukemia cells, indicating that oxidative damage may sensitize toABT-737 induced apoptosis. In addition, we demonstrate that Metformin sensitizes leukemia cells to the oligomerization of Bak, suggesting that the observed synergy with ABT-737 is mediated, at least in part, by enhanced outer mitochondrial membrane permeabilization. Notably, Phenformin was at least 10-fold more potent than Metformin in abrogating electron transport and increasing sensitivity to ABT-737, suggesting that this agent may be better suited for targeting hematological malignancies. Taken together, our results suggest that inhibition of mitochondrial metabolism by Metformin or Phenformin is associated with increased leukemia cell susceptibility to induction of intrinsic apoptosis, and provide a rationale for clinical studies exploring the efficacy of combining biguanides with the orally bioavailable derivative of ABT-737, Venetoclax. PMID:27283492

  13. Nano-Bio Electrochemical Interfacing-Linking Cell Biology and Micro-Electronics

    Science.gov (United States)

    Shacham-Diamand, Y.; Popovtzer, R.; Rishpon, Y.

    Integration of biological substance within electronic devices is an innovative and challenging area combining recent progress in molecular biology and micro technology. First, we introduce the concept of integrating living cells with Micro Electro Mechanical Systems (MEMS). Following a brief overview on "whole cell based biosensors" we describe the design, fabrication, and process of a biocompatible electrochemical "Lab-on-a-Chip" system. Demonstrating the application of electrochemical interfacing based whole cell bio chips, we present two different configurations: a. integration of prokaryotic cells (bacteria) for water toxicity detection, and b. integration of eukaryotic cells (human colon cancer cells) for rapid evaluation of the effectiveness of drug treatments. Both applications, with either microbes or mammalian cells integrated onto MEMS based biochips with liquid volume in the range of 100 nL-1 μL, function well and yield a detectable signal much higher than noise level after few minutes.

  14. Universal electron injection dynamics at nanointerfaces in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei; Wang, Hai-Yu; Fang, Hong-Hua; Gao, Bing-Rong; Chen, Qi-Dai [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun (China); Wang, Hai; Yang, Zhi-Yong; Sun, Hong-Bo [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun (China); College of Physics, Jilin University, Changchun (China); Han, Wei [College of Physics, Jilin University, Changchun (China)

    2012-07-10

    Initial nanointerfacial electron transfer dynamics are studied in dye-sensitized solar cells (DSSCs) in which the free energy and kinetics vary over a broad range. Surprisingly, it is found that the decay profiles, reflecting the electron transfer behavior, show a universal shape despite the different kinds of dye and semiconductor nanocrystalline films, even across different device types. This renews intuitive knowledge about the electron injection process in DSSCs. In order to quantitatively comprehend the universal behavior, a static inhomogeneous electronic coupling model with a Gaussian distribution of local injection energetics is proposed in which only the electron injection rate is a variant. It is confirmed that this model can be extended to CdSe quantum dot-sensitized films. These unambiguous results indicate exactly the same physical distribution in electron injection process of different sensitization films, providing limited simple and important parameters describing the electron injection process including electronic coupling constant and reorganization energy. The results provide insight into photoconversion physics and the design of optimal metal-free organic dye-sensitized photovoltaic devices by molecular engineering. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. The electronic structure engineering of organic dye sensitizers for solar cells: The case of JK derivatives.

    Science.gov (United States)

    Zhang, Cai-Rong; Ma, Jin-Gang; Zhe, Jian-Wu; Jin, Neng-Zhi; Shen, Yu-Lin; Wu, You-Zhi; Chen, Yu-Hong; Liu, Zi-Jiang; Chen, Hong-Shan

    2015-11-05

    The design and development of novel dye sensitizers are effective method to improve the performance of dye-sensitized solar cells (DSSCs) because dye sensitizers have significant influence on photo-to-current conversion efficiency. In the procedure of dye sensitizer design, it is very important to understand how to tune their electronic structures and related properties through the substitution of electronic donors, acceptors, and conjugated bridges in dye sensitizers. Here, the electronic structures and excited-state properties of organic JK dye sensitizers are calculated by using density functional theory (DFT) and time dependent DFT methods. Based upon the calculated results, we investigated the role of different electronic donors, acceptors, and π-conjugated bridges in the modification of electronic structures, absorption properties, as well as the free energy variations for electron injection and dye regeneration. In terms of the analysis of transition configurations and molecular orbitals, the effective chromophores which are favorable for electron injection in DSSCs are addressed. Meanwhile, considering the absorption spectra and free energy variation, the promising electronic donors, π-conjugated bridges, and acceptors are presented to design dye sensitizers.

  16. In situ liquid-cell electron microscopy of silver-palladium galvanic replacement reactions on silver nanoparticles

    National Research Council Canada - National Science Library

    Sutter, E; Jungjohann, K; Bliznakov, S; Courty, A; Maisonhaute, E; Tenney, S; Sutter, P

    2014-01-01

    .... In situ observations by liquid-cell electron microscopy can provide insight into mechanisms, rates and possible modifications of galvanic replacement reactions in the native solution environment...

  17. Comet assay, cloning assay, and light and electron microscopy on one preselected cell

    Science.gov (United States)

    Koenig, Karsten; Oehring, Hartmut; Halbhuber, Karl-Juergen; Fiedler, Ursula; Bauer, Eckhard; Greulich, Karl-Otto

    1998-01-01

    In order to perform long-term studies up to one week on a preselected single cell after micromanipulation (e.g. UVA and NIR microbeam exposure) in comparison with non-treated neighbor cells (control cells) we applied a variety of single cell diagnostic techniques and developed a special comet assay for single preselected cells. For that purpose adherent cells were grown in low concentrations and maintained in special sterile centimeter-sized glass cell chambers. After preselection, a single cell was marked by means of diamond-produced circles on the outer cell chamber window. During exposure to microbeams, NADH-attributed autofluorescence of the chosen cell was detected by fluorescence imaging and spectroscopy. In addition, cell morphology was video-monitored (formation of pseudopodia, membrane blebbing,...). Maintaining the microchamber in the incubator, the irradiated cell was examined 24 h later for cell division (clone formation) and modifications in autofluorescence and morphology (including daughter cells). In the case that no division occurred the vitality of the light-exposed cell and of the control cells were probed by intranuclear propidium iodide accumulation. After fixation, either electron microscopy or single cell gel electrophoresis (comet assay) was performed. To monitor comet formation indicating photoinduced DNA damage in the preselected single cell in comparison with the non-exposed neighbor cells the chamber was filled with low-melting gel and lysis solution and exposed to an electric field. In contrast to the conventional comet assay, where only randomly chosen cells of a suspension are investigated, the novel optimized electrophoresis technique should enhance the possibilities of DNA damage detection to a true single (preselected) cell level. The single cell techniques applied to UVA microexposed Chinese hamster ovary cells (364 nm, 1 mW, 3.5 W/cm2) revealed significant cell damage for J/cm2 fluences such as modifications of intracellular

  18. New electron beam facility for irradiated plasma facing materials testing in hot cell

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, N.; Kawamura, H. [Oarai Research Establishment, Ibaraki-ken (Japan); Akiba, M. [Naka Research Establishment, Ibaraki-ken (Japan)

    1995-09-01

    Since plasma facing components such as the first wall and the divertor for the next step fusion reactors are exposed to high heat loads and high energy neutron flux generated by the plasma, it is urgent to develop of plasma facing components which can resist these. Then, we have established electron beam heat facility ({open_quotes}OHBIS{close_quotes}, Oarai Hot-cell electron Beam Irradiating System) at a hot cell in JMTR (Japan Materials Testing Reactor) hot laboratory in order to estimate thermal shock resistivity of plasma facing materials and heat removal capabilities of divertor elements under steady state heating. In this facility, irradiated plasma facing materials (beryllium, carbon based materials and so on) and divertor elements can be treated. This facility consists of an electron beam unit with the maximum beam power of 50kW and the vacuum vessel. The acceleration voltage and the maximum beam current are 30kV (constant) and 1.7A, respectively. The loading time of electron beam is more than 0.1ms. The shape of vacuum vessel is cylindrical, and the mainly dimensions are 500mm in inner diameter, 1000mm in height. The ultimate vacuum of this vessel is 1 x 10{sup -4}Pa. At present, the facility for thermal shock test has been established in a hot cell. And performance estimation on the electron beam is being conducted. Presently, the devices for heat loading tests under steady state will be added to this facility.

  19. Nanoscale imaging of whole cells using a liquid enclosure and a scanning transmission electron microscope.

    Directory of Open Access Journals (Sweden)

    Diana B Peckys

    Full Text Available Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7 were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM laboratory.

  20. Molecular helices as electron acceptors in high-performance bulk heterojunction solar cells.

    Science.gov (United States)

    Zhong, Yu; Trinh, M Tuan; Chen, Rongsheng; Purdum, Geoffrey E; Khlyabich, Petr P; Sezen, Melda; Oh, Seokjoon; Zhu, Haiming; Fowler, Brandon; Zhang, Boyuan; Wang, Wei; Nam, Chang-Yong; Sfeir, Matthew Y; Black, Charles T; Steigerwald, Michael L; Loo, Yueh-Lin; Ng, Fay; Zhu, X-Y; Nuckolls, Colin

    2015-09-18

    Despite numerous organic semiconducting materials synthesized for organic photovoltaics in the past decade, fullerenes are widely used as electron acceptors in highly efficient bulk-heterojunction solar cells. None of the non-fullerene bulk heterojunction solar cells have achieved efficiencies as high as fullerene-based solar cells. Design principles for fullerene-free acceptors remain unclear in the field. Here we report examples of helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces. Atomic force microscopy reveals a mesh-like network of acceptors with pores that are tens of nanometres in diameter for efficient exciton separation and charge transport. This study describes a new motif for designing highly efficient acceptors for organic solar cells.

  1. Integrated cumulus ensemble and turbulence (ICET): An integrated parameterization system for general circulation models (GCMs)

    Energy Technology Data Exchange (ETDEWEB)

    Evans, J.L.; Frank, W.M.; Young, G.S. [Pennsylvania State Univ., University Park, PA (United States)

    1996-04-01

    Successful simulations of the global circulation and climate require accurate representation of the properties of shallow and deep convective clouds, stable-layer clouds, and the interactions between various cloud types, the boundary layer, and the radiative fluxes. Each of these phenomena play an important role in the global energy balance, and each must be parameterized in a global climate model. These processes are highly interactive. One major problem limiting the accuracy of parameterizations of clouds and other processes in general circulation models (GCMs) is that most of the parameterization packages are not linked with a common physical basis. Further, these schemes have not, in general, been rigorously verified against observations adequate to the task of resolving subgrid-scale effects. To address these problems, we are designing a new Integrated Cumulus Ensemble and Turbulence (ICET) parameterization scheme, installing it in a climate model (CCM2), and evaluating the performance of the new scheme using data from Atmospheric Radiation Measurement (ARM) Program Cloud and Radiation Testbed (CART) sites.

  2. Isolation and Identification of Transforming Growth Factor β from In Vitro Matured Cumulus Oocyte Complexes

    Directory of Open Access Journals (Sweden)

    AULANI’AM

    2012-03-01

    Full Text Available Transforming growth factor-β (TGF-β is a two-chain polypeptide with molecular weight of 25 kDa which takes significant role in the steroidogenesis process. In the ovarian oocyte in particular, TGF-β has an important role in regulating reproductive function. TGF-β represents a key intrafollicular protein that regulates follicle development and aromatization process. The purpose of this research was to characterize and identify a protein fraction of TGF-β from the bovine isolated oocytes, which is synthesized during in vitro oocyte maturation process. Oocytes were collected from follicles with diameter of 3-8 mm. Oocytes were then matured in TCM 199 media supplemented with 5 μg/mg LH, 3% BSA, and 50 μg/ml gentamicin sulfate, and cultured in CO2 incubator (5%, 38.5 oC for 20 hours. TGF-β receptors were identified immunohistochemically. Characteristics of the TGF-β protein were determined using SDS PAGE and TGF-β specification was tested using Western Blotting. The results showed that TGF-β receptors were identified and found in cumulus oocyte complexes (COCs. TGF-β protein was isolated from bovine oocytes with molecular weight 25 kDa and it was identified by Western blotting methods in the same molecular weight.

  3. Effects of entrainment and mixing on droplet size distributions in warm cumulus clouds

    Science.gov (United States)

    Tölle, Merja H.; Krueger, Steven K.

    2014-06-01

    A long-standing problem in cloud physics is the broadening of the cloud droplet spectrum in warm cumulus clouds. To isolate the changes of the droplet size distribution (DSD) due to entrainment and turbulent mixing, we used the Explicit Mixing Parcel Model (EMPM). The EMPM explicitly represents spatial variability due to entrainment and turbulent mixing down to the smallest turbulence scales in a one-dimensional domain. Several thousand individual droplets evolve by condensation or evaporation according to their local environments. We used EMPM results to characterize the evolution of the DSD due to entrainment and isobaric mixing for a wide range of conditions in a 20 m domain, including variations in entrained environmental air fraction, the turbulence dissipation rate, the size of the entrained blobs, and the relative humidity of the entrained air. We found that the broadening of the DSD due to entrainment and isobaric mixing for a specific value of the entrained air relative humidity depends only on the eddy mixing time scale and the LWC after mixing. Broadening increases substantially as the evaporation time scale decreases due to decreasing relative humidity of the entrained air. Our results also show that it is possible to parameterize the effects of entrainment and mixing on the droplet number concentration. The comprehensive results obtained for one set of values of entrained air relative humidity, droplet size, and droplet concentration should be extended to other values.

  4. Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime

    Science.gov (United States)

    Pistone, Kristina; Praveen, Puppala S.; Thomas, Rick M.; Ramanathan, Veerabhadran; Wilcox, Eric M.; Bender, Frida A.-M.

    2017-04-01

    There are multiple factors which affect the micro- and macrophysical properties of clouds, including the atmospheric vertical structure and dominant meteorological conditions in addition to aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood. As bio- and fossil fuel combustion has increased in southeast Asia, corresponding increases in atmospheric aerosol pollution have been seen over the surrounding regions. These emissions notably include black carbon (BC) aerosols, which absorb rather than reflect solar radiation, affecting the atmosphere over the Indian Ocean through direct warming in addition to modifying cloud microphysical properties. The CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign was conducted during the winter monsoon season (February and March) of 2012 in the northern Indian Ocean, a region dominated by trade cumulus clouds. During CARDEX, small unmanned aircraft were deployed, measuring aerosol, radiation, cloud, water vapor fluxes, and meteorological properties while a surface observatory collected continuous measurements of atmospheric precipitable water vapor (PWV), water vapor fluxes, surface and total-column aerosol, and cloud liquid water path (LWP). We present observations which indicate a positive correlation between aerosol and cloud LWP only when considering cases with low atmospheric water vapor (PWV)

  5. From large-eddy simulation to multi-UAVs sampling of shallow cumulus clouds

    Science.gov (United States)

    Lamraoui, Fayçal; Roberts, Greg; Burnet, Frédéric

    2016-04-01

    In-situ sampling of clouds that can provide simultaneous measurements at satisfying spatio-temporal resolutions to capture 3D small scale physical processes continues to present challenges. This project (SKYSCANNER) aims at bringing together cloud sampling strategies using a swarm of unmanned aerial vehicles (UAVs) based on Large-eddy simulation (LES). The multi-UAV-based field campaigns with a personalized sampling strategy for individual clouds and cloud fields will significantly improve the understanding of the unresolved cloud physical processes. An extensive set of LES experiments for case studies from ARM-SGP site have been performed using MesoNH model at high resolutions down to 10 m. The carried out simulations led to establishing a macroscopic model that quantifies the interrelationship between micro- and macrophysical properties of shallow convective clouds. Both the geometry and evolution of individual clouds are critical to multi-UAV cloud sampling and path planning. The preliminary findings of the current project reveal several linear relationships that associate many cloud geometric parameters to cloud related meteorological variables. In addition, the horizontal wind speed indicates a proportional impact on cloud number concentration as well as triggering and prolonging the occurrence of cumulus clouds. In the framework of the joint collaboration that involves a Multidisciplinary Team (including institutes specializing in aviation, robotics and atmospheric science), this model will be a reference point for multi-UAVs sampling strategies and path planning.

  6. Grb10 characterization in bovine cumulus oocyte complexes from different follicle sizes

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Antunes da Rosa

    2015-05-01

    Full Text Available The objective of this study was to investigate the mRNA expression and protein localization of Grb10 gene in bovine cumulus-oocyte complexes (COCs from different follicle sizes. Firstly, it was investigated the mRNA expression to correlate with maturation rates. COCs from follicles at 1-3, 4-6, 6-8 and >8mm were used to evaluate Grb10 gene expression by qRT-PCR assay and nuclear maturation rates. It was observed that more competent oocytes (from follicles at 6-8 and >8mm; P>0.05, had lower Grb10 mRNA expression levels when compared to the oocytes from follicles at 1-3 and 4-6mm (P>0.05. After it was performed an immunofluorescence analysis in COCs from different follicle sizes (1-3, 4-6, 6-8 and >8mm to investigate Grb10 protein localization. Samples were incubated with primary antibody: Polyclonal rabbit anti-Grb10 (1:100. Primary antibody was detected using goat anti-rabbit IgG antibody conjugated with Alexa Fluor 488 (1:500. Positive fluorescence signal was detected in all analyzed samples but less evident in COCs from largest follicles. These results characterized Grb10 gene in bovine COC and provide evidences for its involvement during oocyte molecular maturation.

  7. Tumor cell death induced by the inhibition of mitochondrial electron transport: The effect of 3-hydroxybakuchiol

    Energy Technology Data Exchange (ETDEWEB)

    Jaña, Fabián [Clinical and Molecular Pharmacology Program, University of Chile, Santiago (Chile); Faini, Francesca [Department of Chemistry, Faculty of Sciences, University of Chile, Santiago (Chile); Lapier, Michel; Pavani, Mario [Clinical and Molecular Pharmacology Program, University of Chile, Santiago (Chile); Kemmerling, Ulrike [Anatomy and Developmental Biology Program, ICBM, Faculty of Medicine, University of Chile, Santiago (Chile); Morello, Antonio; Maya, Juan Diego; Jara, José [Clinical and Molecular Pharmacology Program, University of Chile, Santiago (Chile); Parra, Eduardo [Laboratory of Experimental Biomedicine, University of Tarapaca, Campus Esmeralda, Iquique (Chile); Ferreira, Jorge, E-mail: jferreir@med.uchile.cl [Clinical and Molecular Pharmacology Program, University of Chile, Santiago (Chile)

    2013-10-15

    Changes in mitochondrial ATP synthesis can affect the function of tumor cells due to the dependence of the first step of glycolysis on mitochondrial ATP. The oxidative phosphorylation (OXPHOS) system is responsible for the synthesis of approximately 90% of the ATP in normal cells and up to 50% in most glycolytic cancers; therefore, inhibition of the electron transport chain (ETC) emerges as an attractive therapeutic target. We studied the effect of a lipophilic isoprenylated catechol, 3-hydroxybakuchiol (3-OHbk), a putative ETC inhibitor isolated from Psoralea glandulosa. 3-OHbk exerted cytotoxic and anti-proliferative effects on the TA3/Ha mouse mammary adenocarcinoma cell line and induced a decrease in the mitochondrial transmembrane potential, the activation of caspase-3, the opening of the mitochondrial permeability transport pore (MPTP) and nuclear DNA fragmentation. Additionally, 3-OHbk inhibited oxygen consumption, an effect that was completely reversed by succinate (an electron donor for Complex II) and duroquinol (electron donor for Complex III), suggesting that 3-OHbk disrupted the electron flow at the level of Complex I. The inhibition of OXPHOS did not increase the level of reactive oxygen species (ROS) but caused a large decrease in the intracellular ATP level. ETC inhibitors have been shown to induce cell death through necrosis and apoptosis by increasing ROS generation. Nevertheless, we demonstrated that 3-OHbk inhibited the ETC and induced apoptosis through an interaction with Complex I. By delivering electrons directly to Complex III with duroquinol, cell death was almost completely abrogated. These results suggest that 3-OHbk has antitumor activity resulting from interactions with the ETC, a system that is already deficient in cancer cells. - Highlights: • We studied the anticancer activity of a natural compound, 3-OHbk, on TA3/Ha cells. • 3-OHbk inhibited mitochondrial electron flow by interacting with Complex I. • Complex I inhibition did

  8. Direct visualization of HIV-1 with correlative live-cell microscopy and cryo-electron tomography

    National Research Council Canada - National Science Library

    Jun, Sangmi; Ke, Danxia; Debiec, Karl; Zhao, Gongpu; Meng, Xin; Ambrose, Zandrea; Gibson, Gregory A; Watkins, Simon C; Zhang, Peijun

    2011-01-01

    Cryo-electron tomography (cryoET) allows 3D visualization of cellular structures at molecular resolution in a close-to-native state and therefore has the potential to help elucidate early events of HIV-1 infection in host cells...

  9. Developments in application of light and scanning electron microscopy techniques for cell wall degradation studies.

    NARCIS (Netherlands)

    Engels, F.M.

    1996-01-01

    The results of recent technological developments in light and scanning electron microscopy closely used for research on forage cell wall degradation in ruminants, are reviewed. The indigestibility of forages by rumen microorganisms used to be ascribed mainly to an overall presence of lignin in the p

  10. Mapping boron in silicon solar cells using electron energy-loss spectroscopy

    DEFF Research Database (Denmark)

    Duchamp, Martial; Boothroyd, Chris; Kovács, András

    2011-01-01

    Electron energy-loss spectroscopy (EELS) is used to study the B distribution in a p-i-n layered solar cell structure. The boron concentration in the p-doped Si layer is expected to be ~1021 cm−3 and should not exceed 1017 cm−3 in the neighbouring intrinsic layer. We show that B concentrations...

  11. More stable hybrid organic solar cells deposited on amorphous Si electron transfer layer

    Energy Technology Data Exchange (ETDEWEB)

    Samiee, Mehran; Modtland, Brian; Dalal, Vikram L., E-mail: vdalal@iastate.edu [Iowa State University, Dept. of Electrical and Computer Engineering, Ames, Iowa 50011 (United States); Aidarkhanov, Damir [Nazarbayev University, Astana (Kazakhstan)

    2014-05-26

    We report on defect densities, performance, and stability of organic/inorganic hybrid solar cells produced using n-doped inorganic amorphous silicon-carbide layers as the electron transport layer (ETL). The organic material was poly-3-hexyl-thiophene (P3HT) and heterojunction was formed using phenyl-C{sub 71}-Butyric-Acid-Methyl Ester (PCBM). For comparison, inverted solar cells fabricated using Cs{sub 2}CO{sub 3} as ETL were fabricated. Defect densities and subgap quantum efficiency curves were found to be nearly identical for both types of cells. The cells were subjected to 2xsun illumination and it was found that the cells produced using doped a-Si as ETL were much more stable than the cells produced using Cs{sub 2}CO{sub 3}.

  12. Molecular Understanding of Fullerene - Electron Donor Interactions in Organic Solar Cells

    KAUST Repository

    Ryno, Sean M.

    2016-09-13

    Organic solar cells hold promise of providing low-cost, renewable power generation, with current devices providing up to 13% power conversion efficiency. The rational design of more performant systems requires an in-depth understanding of the interactions between the electron donating and electron accepting materials within the active layers of these devices. Here, we explore works that give insight into the intermolecular interactions between electron donors and electron acceptors, and the impact of molecular orientations and environment on these interactions. We highlight, from a theoretical standpoint, the effects of intermolecular interactions on the stability of charge carriers at the donor/acceptor interface and in the bulk and how these interactions influence the nature of the charge transfer states as wells as the charge separation and charge transport processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Investigating the use of in situ liquid cell scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nguy, Amanda [Iowa State Univ., Ames, IA (United States)

    2016-02-19

    Engineering nanoparticles with desired shape-dependent properties is the key to many applications in nanotechnology. Although many synthetic procedures exist to produce anisotropic gold nanoparticles, the dynamics of growth are typically unknown or hypothetical. In the case of seed-mediated growth in the presence of DNA into anisotropic nanoparticles, it is not known exactly how DNA directs growth into specific morphologies. A series of preliminary experiments were carried out to contribute to the investigation of the possible mechanism of DNA-mediated growth of gold nanoprisms into gold nanostars using liquid cell scanning transmission electron microscopy (STEM). Imaging in the liquid phase was achieved through the use of a liquid cell platform and liquid cell holder that allow the sample to be contained within a “chip sandwich” between two electron transparent windows. Ex situ growth experiments were performed using Au-T30 NPrisms (30-base thymine oligonucleotide-coated gold nanoprisms) that are expected to grow into gold nanostars. Growth to form these nanostars were imaged using TEM (transmission electron microscopy) and liquid cell STEM (scanning transmission electron microscopy). An attempt to perform in situ growth experiments with the same Au-T30 nanoprisms revealed challenges in obtaining desired morphology results due to the environmental differences within the liquid cell compared to the ex situ environment. Different parameters in the experimental method were explored including fluid line set up, simultaneous and alternating reagent addition, and the effect of different liquid cell volumes to ensure adequate flow of reagents into the liquid cell. Lastly, the binding affinities were compared for T30 and A30 DNA incubated with gold nanoparticles using zeta potential measurements, absorption spectroscopy, and isothermal titration calorimetry (ITC). It was previously reported thymine bases have a lower binding affinity to gold surfaces than adenine

  14. Competence Classification of Cumulus and Granulosa Cell Transcriptome in Embryos Matched by Morphology and Female Age

    DEFF Research Database (Denmark)

    Borup, Rehannah; Thuesen, Lea Langhoff; Andersen, Claus Yding;

    2016-01-01

    prediction analysis using machine learning algorithms (support vector machines) with performance estimation by leave-one-out cross validation and independent validation on an external data set. RESULTS: We defined a signature of 30 genes expressed in CC predictive of live birth. This live birth prediction...

  15. Gene expression of cumulus cells in women with poor ovarian response after dehydroepiandrosterone supplementation

    Directory of Open Access Journals (Sweden)

    Kuan-Hao Tsui

    2014-12-01

    Conclusion: The study showed that DHEA therapy positively affected the gene expression of CCs in women with POR, and provided evidence to support the positive effect of DHEA supplementation on women with POR.

  16. Competence classification of cumulus and granulosa cell transcriptome in embryos matched by morphology and female age

    DEFF Research Database (Denmark)

    Helweg-Larsen, Rehannah Borup; Thuesen, Lea Langhoff; Andersen, Claus Yding

    2016-01-01

    prediction analysis using machine learning algorithms (support vector machines) with performance estimation by leave-one-out cross validation and independent validation on an external data set. RESULTS: We defined a signature of 30 genes expressed in CC predictive of live birth. This live birth prediction...

  17. Effects of Light and Electron Beam Irradiation on Halide Perovskites and Their Solar Cells.

    Science.gov (United States)

    Klein-Kedem, Nir; Cahen, David; Hodes, Gary

    2016-02-16

    Hybrid alkylammonium lead halide perovskite solar cells have, in a very few years of research, exceeded a light-to-electricity conversion efficiency of 20%, not far behind crystalline silicon cells. These perovskites do not contain any rare element, the amount of toxic lead used is very small, and the cells can be made with a low energy input. They therefore already conform to two of the three requirements for viable, commercial solar cells-efficient and cheap. The potential deal-breaker is their long-term stability. While reasonable short-term (hours) and even medium term (months) stability has been demonstrated, there is concern whether they will be stable for the two decades or more expected from commercial cells in view of the intrinsically unstable nature of these materials. In particular, they have a tendency to be sensitive to various types of irradiation, including sunlight, under certain conditions. This Account focuses on the effect of irradiation on the hybrid (and to a small degree, all-inorganic) lead halide perovskites and their solar cells. It is split up into two main sections. First, we look at the effect of electron beams on the materials. This is important, since such beams are used for characterization of both the perovskites themselves and cells made from them (electron microscopy for morphological and compositional characterization; electron beam-induced current to study cell operation mechanism; cathodoluminescence for charge carrier recombination studies). Since the perovskites are sensitive to electron beam irradiation, it is important to minimize beam damage to draw valid conclusions from such measurements. The second section treats the effect of visible and solar UV irradiation on the perovskites and their cells. As we show, there are many such effects. However, those affecting the perovskite directly need not necessarily always be detrimental to the cells, while those affecting the solar cells, which are composed of several other phases

  18. Patterned 3-dimensional metal grid electrodes as alternative electron collectors in dye-sensitized solar cells.

    Science.gov (United States)

    Chua, Julianto; Mathews, Nripan; Jennings, James R; Yang, Guangwu; Wang, Qing; Mhaisalkar, Subodh G

    2011-11-21

    We describe the application of 3-dimensional metal grid electrodes (3D-MGEs) as electron collectors in dye-sensitized solar cells (DSCs) as a replacement for fluorinated tin oxide (FTO) electrodes. Requirements, structure, advantages, and limitations of the metal grid electrodes are discussed. Solar conversion efficiencies of 6.2% have been achieved in 3D-MGE based solar cells, comparable to that fabricated on FTO (7.1%). The charge transport properties and collection efficiencies in these novel solar cells have been studied using electrochemical impedance spectroscopy.

  19. Transmission electron microscopy reveals distinct macrophage- and tick cell-specific morphological stages of Ehrlichia chaffeensis.

    Directory of Open Access Journals (Sweden)

    Sarah E Dedonder

    Full Text Available BACKGROUND: Ehrlichia chaffeensis is an emerging tick-borne rickettsial pathogen responsible for human monocytic ehrlichiosis. Despite the induction of an active host immune response, the pathogen has evolved to persist in its vertebrate and tick hosts. Understanding how the organism progresses in tick and vertebrate host cells is critical in identifying effective strategies to block the pathogen transmission. Our recent molecular and proteomic studies revealed differences in numerous expressed proteins of the organism during its growth in different host environments. METHODOLOGY/PRINCIPAL FINDINGS: Transmission electron microscopy analysis was performed to assess morphological changes in the bacterium within macrophages and tick cells. The stages of pathogen progression observed included the attachment of the organism to the host cells, its engulfment and replication within a morulae by binary fission and release of the organisms from infected host cells by complete host cell lysis or by exocytosis. E. chaffeensis grown in tick cells was highly pleomorphic and appears to replicate by both binary fission and filamentous type cell divisions. The presence of Ehrlichia-like inclusions was also observed within the nucleus of both macrophages and tick cells. This observation was confirmed by confocal microscopy and immunoblot analysis. CONCLUSIONS/SIGNIFICANCE: Morphological differences in the pathogen's progression, replication, and processing within macrophages and tick cells provide further evidence that E. chaffeensis employs unique host-cell specific strategies in support of adaptation to vertebrate and tick cell environments.

  20. Capacitance and conductance studies on silicon solar cells subjected to 8 MeV electron irradiations

    Science.gov (United States)

    Sathyanarayana Bhat, P.; Rao, Asha; Sanjeev, Ganesh; Usha, G.; Priya, G. Krishna; Sankaran, M.; Puthanveettil, Suresh E.

    2015-06-01

    The space grade silicon solar cells were irradiated with 8 MeV electrons with doses ranging from 5-100 k Gy. Capacitance and conductance measurements were carried out in order to investigate the anomalous degradation of the cells in the radiation harsh environments and the results are presented in this paper. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements were performed to extract the information about the interface trap states. The small increase in density of interface states was observed from the conductance-frequency measurements. The reduction in carrier concentration upon electron irradiation is due to the trapping of charge carriers by the radiation induced trap centres. The Drive Level Capacitance Profiling (DLCP) technique has been applied to study the properties of defects in silicon solar cells. A small variation in responding state densities with measuring frequency was observed and the defect densities are in the range 1015 -1016 cm-3.

  1. Validation of cell-free culture using scanning electron microscopy (SEM) and gene expression studies.

    Science.gov (United States)

    Yang, R; Elankumaran, Y; Hijjawi, N; Ryan, U

    2015-06-01

    A cell-free culture system for Cryptosporidium parvum was analysed using scanning electron microscopy (SEM) to characterise life cycle stages and compare gene expression in cell-free culture and cell culture using HCT-8 cells. Cryptosporidium parvum samples were harvested at 2 h, 8 h, 14 h, 26 h, 50 h, 74 h, 98 h, 122 h and 170 h, chemically fixed and specimens were observed using a Zeiss 1555 scanning electron microscope. The presence of sporozoites, trophozoites and type I merozoites were identified by SEM. Gene expression in cell culture and cell-free culture was studied using reverse transcriptase quantitative PCR (RT-qPCR) of the sporozoite surface antigen protein (cp15), the glycoprotein 900 (gp900), the Cryptosporidium oocyst wall protein (COWP) and 18S ribosomal RNA (rRNA) genes in both cell free and conventional cell culture. In cell culture, cp15 expression peaked at 74 h, gp900 expression peaked at 74 h and 98 h and COWP expression peaked at 50 h. In cell-free culture, CP15 expression peaked at 98 h, gp900 expression peaked at 74 h and COWP expression peaked at 122 h. The present study is the first to compare gene expression of C. parvum in cell culture and cell-free culture and to characterise life cycle stages of C. parvum in cell-free culture using SEM. Findings from this study showed that gene expression patterns in cell culture and cell-free culture were similar but in cell-free culture, gene expression was delayed for CP15 and COWP in cell free culture compared with the cell culture system and was lower. Although three life cycle stageswere conclusively identified, improvements in SEM methodology should lead to the detection of more life cycle stages.

  2. An overview of power electronics applications in fuel cell systems: DC and AC converters.

    Science.gov (United States)

    Ali, M S; Kamarudin, S K; Masdar, M S; Mohamed, A

    2014-01-01

    Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter.

  3. Performance evaluation of aluminum/phosphate cell for powering small electronic devices

    Directory of Open Access Journals (Sweden)

    Gymama Slaughter

    2015-12-01

    Full Text Available We report on an innovative membrane-free aluminum/phosphate cell based on the activation of aluminum (Al as anodic material using ZnO nanocrystal in phosphate rich electrolyte that is capable of generating sufficient power to power a light-emitting diode (LED, selected as a model of a small electronic device. The energy from the cell is periodically supplied in high power bursts due to the charge and discharge cycle of the capacitor. The entire process is controlled by a switched capacitor regulator. The Al/phosphate cell was studied in neutral 100 mM phosphate buffer solution (7.4 at a temperature of 25 °C. We demonstrate that two Al/phosphate cells connected in series can generate an open circuit voltage (Voc up to 1.66 V to continuously power a LED via a switched capacitor regulator circuit. The switched capacitor regulator circuit enabled the 1 μF capacitor to store the incoming power from the cell and discharge it in a large power burst to supply the necessary drive strength required by the LED. This new Al/phosphate cell configuration is a ‘green’ alternative to the use of glucose abiotic and biofuel cells for powering ultra-low power implantable electronic devices.

  4. Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells.

    Science.gov (United States)

    Havrdova, M; Polakova, K; Skopalik, J; Vujtek, M; Mokdad, A; Homolkova, M; Tucek, J; Nebesarova, J; Zboril, R

    2014-12-01

    When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine.

  5. Electron and hole drift mobility measurements on thin film CdTe solar cells

    Science.gov (United States)

    Long, Qi; Dinca, Steluta A.; Schiff, E. A.; Yu, Ming; Theil, Jeremy

    2014-07-01

    We report electron and hole drift mobilities in thin film polycrystalline CdTe solar cells based on photocarrier time-of-flight measurements. For a deposition process similar to that used for high-efficiency cells, the electron drift mobilities are in the range of 10-1-100 cm2/V s, and holes are in the range of 100-101 cm2/V s. The electron drift mobilities are about a thousand times smaller than those measured in single crystal CdTe with time-of-flight; the hole mobilities are about ten times smaller. Cells were examined before and after a vapor phase treatment with CdCl2; treatment had little effect on the hole drift mobility, but decreased the electron mobility. We are able to exclude bandtail trapping and dispersion as a mechanism for the small drift mobilities in thin film CdTe, but the actual mechanism reducing the mobilities from the single crystal values is not known.

  6. Scanning electron microscopic study of human neuroblastoma cells affected with Naegleria fowleri Thai strains.

    Science.gov (United States)

    Tiewcharoen, Supathra; Rabablert, Jundee; Chetanachan, Pruksawan; Junnu, Virach; Worawirounwong, Dusit; Malainual, Nat

    2008-10-01

    In order to understand the pathogenesis of Naegleria fowleri in primary amoebic meningoencephalitis, the human neuroblastoma (SK-N-MC) and African green monkey kidney (Vero) cells were studied in vitro. Amoeba suspension in cell-culture medium was added to the confluent monolayer of SK-N-MC and Vero cells. The cytopathic activity of N. fowleri trophozoites in co-culture system was elucidated by scanning electron microscope at 3, 6, 9, 12, and 24 h. Two strains of N. fowleri displayed well-organized vigorous pseudopods in Nelson's medium at 37 degrees C. In co-culture, the target monolayer cells were damaged by two mechanisms, phagocytosis by vigorous pseudopods and engulfment by sucker-like apparatus. N. fowleri trophozoites produced amoebostomes only in co-culture with SK-N-MC cells. In contrast, we could not find such apparatus in the co-culture with Vero cells. The complete destruction time (100%) at 1:1 amoeba/cells ratio of SK-N-MC cells (1 day) was shorter than the Vero cells (12 days). In conclusion, SK-N-MC cells were confirmed to be a target model for studying neuropathogenesis of primary amoebic meningoencephalitis.

  7. Comparative electron microscopy of basophils and mast cells, in vivo and in vitro.

    Science.gov (United States)

    Eguchi, M

    1991-01-01

    We compared the fine structure and electron microscopic cytochemical findings of basophils and mast cells from humans, guinea pigs, rabbits, mice and rats. The particulate structure was the most frequently observed and most typical structure of human and rabbit basophil granules and of guinea pig mast cell granules. The most prominent feature of guinea pig basophils and murine mast cells was that the fine structure of the granules was homogeneous. The fine structure of the granules in guinea pig basophils resembled that in murine mast cells, while the fine structure of the granules of guinea pig mast cells resembled those in human and rabbit mast cells. In mouse mast cells in culture, the majority of the granules contained small vesicles, which were also observed in human basophils in culture and in mouse basophils in vivo. The degrees of cytochemical reactivity of acid mucopolysaccharides among the species were different. Peroxidase activity was positive in most basophils and in human mast cells. Among mammals, the granules of basophils and mast cells present heterogeneous fine structure. It is of interest that the basophil granules of some species resemble the mast cell granules rather than the basophil granules of other species.

  8. Transmission electron microscopy and atomic force microscopy characterization of nickel deposition on bacterial cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Recently bacterial cells have become attractive biological templates for the fabrication of metal nano- structures or nanomaterials due to their inherent small size, various standard geometrical shapes and abundant source. In this paper, nickel-coated bacterial cells (gram-negative bacteria of Escherichia coli) were fabricated via electroless chemical plating. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) characterization results reveal evident morphological difference between bacterial cells before and after deposition with nickel. The bare cells with smooth surface presented transverse outspreading effect at mica surface. Great changes took place in surface roughness for those bacterial cells after metallization. A large number of nickel nanoparticles were observed to be equably distributed at bacterial surface after activation and subsequent metallization. Furthermore, ultra thin section analytic results validated the presence and uniformity of thin nickel coating at bacterial surface after metallization.

  9. Responses of indigenous microorganisms to soil incubation as viewed by transmission electron microscopy of cell thin sections.

    Science.gov (United States)

    Bae, h. C.; Casida, L. E., Jr.

    1973-01-01

    Indigenous soil microorganisms were cultivated in their soil habitat with 50% moisture capacity at 30 C for two weeks. Changes in microorganism cells were studied by electron microscopy during incubation, with particular attention to the dormant cell growth and to the ability of cystlike cells to germinate and reencyst. The responses of various cell species to incubation conditions are described and illustrated by photomicrographs.

  10. Electron Debye scale Kelvin-Helmholtz instability: Electrostatic particle-in-cell simulations

    Science.gov (United States)

    Lee, Sang-Yun; Lee, Ensang; Kim, Khan-Hyuk; Lee, Dong-Hun; Seon, Jongho; Jin, Ho

    2015-12-01

    In this paper, we investigated the electron Debye scale Kelvin-Helmholtz (KH) instability using two-dimensional electrostatic particle-in-cell simulations. We introduced a velocity shear layer with a thickness comparable to the electron Debye length and examined the generation of the KH instability. The KH instability occurs in a similar manner as observed in the KH instabilities in fluid or ion scales producing surface waves and rolled-up vortices. The strength and growth rate of the electron Debye scale KH instability is affected by the structure of the velocity shear layer. The strength depends on the magnitude of the velocity and the growth rate on the velocity gradient of the shear layer. However, the development of the electron Debye scale KH instability is mainly determined by the electric field generated by charge separation. Significant mixing of electrons occurs across the shear layer, and a fraction of electrons can penetrate deeply into the opposite side fairly far from the vortices across the shear layer.

  11. Three-dimensional visualization of virus-infected cells by serial sectioning: an electron microscopic study using resin embedded cells.

    Science.gov (United States)

    Schauflinger, Martin; Villinger, Clarissa; Walther, Paul

    2013-01-01

    In this paper we show how to obtain a three-dimensional model of virus-infected cells by serial sectioning of resin embedded samples and transmission electron microscopic imaging. The method bases on sample fixation by high pressure freezing and processing by freeze substitution with the goal to preserve the structures of interest close to the natural state, as previously described (Walther et al., High pressure freezing for scanning transmission electron tomography analysis of cellular organelles. In: Mossman BT, Taatjes DJ (eds) Cell imaging techniques, vol 931, Methods in molecular biology. Humana Press, Totowa, NJ, pp 525-535, 2013). Advantages of serial sectioning compared to that of other tomographic methods are as follows: No special and expensive additional equipment is required. Relatively large volumes, such as whole cells, can be three-dimensionally reconstructed in a reasonable amount of time. Serial sectioning is a non-destructive method; the sections can be stored, re-imaged, or processed for immunogold labeling when more specific data are requested or when new scientific questions are raised (e.g., higher magnifications, protein distributions). We have recently used this method to obtain a three-dimensional model of the complete assembly complex of an HCMV infected cell, which allowed a detailed insight into this virally induced compartment (Schauflinger et al., Cell Microbiol 15(2):305-314, 2013).

  12. Revealing dynamic processes of materials in liquids using liquid cell transmission electron microscopy.

    Science.gov (United States)

    Niu, Kai-Yang; Liao, Hong-Gang; Zheng, Haimei

    2012-12-20

    The recent development for in situ transmission electron microscopy, which allows imaging through liquids with high spatial resolution, has attracted significant interests across the research fields of materials science, physics, chemistry and biology. The key enabling technology is a liquid cell. We fabricate liquid cells with thin viewing windows through a sequential microfabrication process, including silicon nitride membrane deposition, photolithographic patterning, wafer etching, cell bonding, etc. A liquid cell with the dimensions of a regular TEM grid can fit in any standard TEM sample holder. About 100 nanoliters reaction solution is loaded into the reservoirs and about 30 picoliters liquid is drawn into the viewing windows by capillary force. Subsequently, the cell is sealed and loaded into a microscope for in situ imaging. Inside the TEM, the electron beam goes through the thin liquid layer sandwiched between two silicon nitride membranes. Dynamic processes of nanoparticles in liquids, such as nucleation and growth of nanocrystals, diffusion and assembly of nanoparticles, etc., have been imaged in real time with sub-nanometer resolution. We have also applied this method to other research areas, e.g., imaging proteins in water. Liquid cell TEM is poised to play a major role in revealing dynamic processes of materials in their working environments. It may also bring high impact in the study of biological processes in their native environment.

  13. Correlative scanning electron and confocal microscopy imaging of labeled cells coated by indium-tin-oxide

    KAUST Repository

    Rodighiero, Simona

    2015-03-22

    Confocal microscopy imaging of cells allows to visualize the presence of specific antigens by using fluorescent tags or fluorescent proteins, with resolution of few hundreds of nanometers, providing their localization in a large field-of-view and the understanding of their cellular function. Conversely, in scanning electron microscopy (SEM), the surface morphology of cells is imaged down to nanometer scale using secondary electrons. Combining both imaging techniques have brought to the correlative light and electron microscopy, contributing to investigate the existing relationships between biological surface structures and functions. Furthermore, in SEM, backscattered electrons (BSE) can image local compositional differences, like those due to nanosized gold particles labeling cellular surface antigens. To perform SEM imaging of cells, they could be grown on conducting substrates, but obtaining images of limited quality. Alternatively, they could be rendered electrically conductive, coating them with a thin metal layer. However, when BSE are collected to detect gold-labeled surface antigens, heavy metals cannot be used as coating material, as they would mask the BSE signal produced by the markers. Cell surface could be then coated with a thin layer of chromium, but this results in a loss of conductivity due to the fast chromium oxidation, if the samples come in contact with air. In order to overcome these major limitations, a thin layer of indium-tin-oxide was deposited by ion-sputtering on gold-decorated HeLa cells and neurons. Indium-tin-oxide was able to provide stable electrical conductivity and preservation of the BSE signal coming from the gold-conjugated markers. © 2015 Wiley Periodicals, Inc.

  14. Correlative scanning electron and confocal microscopy imaging of labeled cells coated by indium-tin-oxide.

    Science.gov (United States)

    Rodighiero, Simona; Torre, Bruno; Sogne, Elisa; Ruffilli, Roberta; Cagnoli, Cinzia; Francolini, Maura; Di Fabrizio, Enzo; Falqui, Andrea

    2015-06-01

    Confocal microscopy imaging of cells allows to visualize the presence of specific antigens by using fluorescent tags or fluorescent proteins, with resolution of few hundreds of nanometers, providing their localization in a large field-of-view and the understanding of their cellular function. Conversely, in scanning electron microscopy (SEM), the surface morphology of cells is imaged down to nanometer scale using secondary electrons. Combining both imaging techniques have brought to the correlative light and electron microscopy, contributing to investigate the existing relationships between biological surface structures and functions. Furthermore, in SEM, backscattered electrons (BSE) can image local compositional differences, like those due to nanosized gold particles labeling cellular surface antigens. To perform SEM imaging of cells, they could be grown on conducting substrates, but obtaining images of limited quality. Alternatively, they could be rendered electrically conductive, coating them with a thin metal layer. However, when BSE are collected to detect gold-labeled surface antigens, heavy metals cannot be used as coating material, as they would mask the BSE signal produced by the markers. Cell surface could be then coated with a thin layer of chromium, but this results in a loss of conductivity due to the fast chromium oxidation, if the samples come in contact with air. In order to overcome these major limitations, a thin layer of indium-tin-oxide was deposited by ion-sputtering on gold-decorated HeLa cells and neurons. Indium-tin-oxide was able to provide stable electrical conductivity and preservation of the BSE signal coming from the gold-conjugated markers.

  15. Aerosol effects on the development of cumulus clouds over the Tibetan Plateau

    Science.gov (United States)

    Zhou, Xu; Bei, Naifang; Liu, Hongli; Cao, Junji; Xing, Li; Lei, Wenfang; Molina, Luisa T.; Li, Guohui

    2017-06-01

    The aerosol-cloud interaction over the Tibetan Plateau has been investigated using a cloud-resolving weather research and forecasting model with a two-moment bulk microphysical scheme including aerosol effects on cloud condensation nuclei and ice nuclei. Two types of cumulus clouds with a similar convective available potential energy, occurring over the Tibetan Plateau (Cu-TP) and North China Plain (Cu-NCP) in August 2014, are simulated to explore the response of convective clouds to aerosols. A set of aerosol profiles is used in the simulations, with the surface aerosol number concentration varying from 20 to 9000 cm-3 and the sulfate mass concentration varying from 0.02 to 9.0 µg cm-3. Increasing aerosol concentrations generally enhances the cloud core updraft and maximum updraft, intensifying convections in Cu-TP and Cu-NCP. However, the core updraft is much stronger in Cu-TP than Cu-NCP, because of the early occurrence of the glaciation process in Cu-TP that is triggered at an elevation above 4000 m. The precipitation increases steadily with aerosol concentrations in Cu-NCP, caused by the suppression of the warm rain but occurrence of efficient mix-phased precipitation due to the reduced cloud droplet size. The precipitation in Cu-TP also increases with aerosol concentrations, but the precipitation enhancement is not substantial compared to that in Cu-NCP with high aerosol concentrations. The aerosol-induced intensification of convections in Cu-TP not only facilitates the precipitation but also transports more ice-phase hydrometeors into the upper troposphere to decrease the precipitation efficiency. Considering the very clean atmosphere over the Tibetan Plateau, elevated aerosol concentrations can remarkably enhance convections due to its specific topography, which not only warms the middle troposphere to influence the Asian summer monsoon but also delivers hydrometeors into the upper troposphere to allow more water vapor to travel into the lower stratosphere.

  16. Morphology and location of attached follicular cumulus-oocyte complexes in horses, cattle and llamas.

    Science.gov (United States)

    Del Campo, M R; Del Campo, C H; Mapletoft, R J; Ginther, O J

    1995-02-01

    Morphology and location of the attached cumulus-oocyte complex (COC) were studied in slaughter-house ovaries in horses (49 follicles, 9 to 44 mm), cattle (68 follicles, 6 to 18 mm), and llamas (38 follicles, 3 to 14 mm). The expected point of ovulation was marked, using the ovulation fossa in mares and the center of the projecting follicular surface in cattle and llamas. A follicle was dissected from an ovary, and tissue was removed from the follicle until the COC became visible by transillumination. However, most llama follicles protruded prominently from the ovarian surface so that dissection was not required to locate the COC. The COC was more readily recognized from the external follicular surface in mares and llamas than in cattle, primarily because of a dark oocyte. Compact COC's projected into the antrum with a smooth dome-shape in horses. The COC's in cattle were also dome-shaped but were more irregular and a few contained prominent processes. The mean diameter of the isolated follicle was calculated from 3 planes, except that in llamas the follicles were spherical so that the 3 dimensions were identical. The angle between a straight line connecting the expected ovulation site and the opposite pole and a straight line from the ovulation site to the COC was defined as the COC-location angle. This angle was chosen because it is unaltered by size of a sphere (45 degrees for a COC at the equator). The mean (+/-SEM) COC-location angle differed (P < 0.01) among horses (39.9 +/- 3.3), cattle (50.0 +/- 2.5), and llamas (64.8 +/- 2.1). In mares, the locations of the COC's did not differ from equality between follicular hemispheres, but in cattle and llamas the COC's were located with greater frequency (P < 0.05) in the hemisphere containing the expected ovulation site (cattle, 65%; llamas, 91%).

  17. Evaluation of the atmospheric transport in a GCM using radon measurements: sensitivity to cumulus convection parameterization

    Directory of Open Access Journals (Sweden)

    K. Zhang

    2008-05-01

    Full Text Available The radioactive species radon (222Rn has long been used as a test tracer for the numerical simulation of large scale transport processes. In this study, radon transport experiments are carried out using an atmospheric GCM with a finite-difference dynamical core, the van Leer type FFSL advection algorithm, and two state-of-the-art cumulus convection parameterization schemes. Measurements of surface concentration and vertical distribution of radon collected from the literature are used as references in model evaluation.

    The simulated radon concentrations using both convection schemes turn out to be consistent with earlier studies with many other models. Comparison with measurements indicates that at the locations where significant seasonal variations are observed in reality, the model can reproduce both the monthly mean surface radon concentration and the annual cycle quite well. At those sites where the seasonal variation is not large, the model is able to give a correct magnitude of the annual mean. In East Asia, where radon simulations are rarely reported in the literature, detailed analysis shows that our results compare reasonably well with the observations.

    The most evident changes caused by the use of a different convection scheme are found in the vertical distribution of the tracer. The scheme associated with weaker upward transport gives higher radon concentration up to about 6 km above the surface, and lower values in higher altitudes. In the lower part of the atmosphere results from this scheme does not agree as well with the measurements as the other scheme. Differences from 6 km to the model top are even larger, although we are not yet able to tell which simulation is better due to the lack of observations at such high altitudes.

  18. Evaluation of the atmospheric transport in a GCM using radon measurements: sensitivity to cumulus convection parameterization

    Directory of Open Access Journals (Sweden)

    K. Zhang

    2008-02-01

    Full Text Available The radioactive species radon (222Rn has long been used as a test tracer for the numerical simulation of large scale transport processes. In this study, radon transport experiments are carried out using an atmospheric GCM with a finite-difference dynamical core, the van Leer type FFSL advection algorithm and two state-of-the-art cumulus convection parameterization schemes. Measurements of surface concentration and vertical distribution of radon collected from literature are used as references in model evaluation.

    The simulated radon concentrations using both convection schemes turn out to be consistent with earlier studies with many other models. Comparison with measurements indicates that at the locations where significant seasonal variations are observed in reality, the model can reproduce both the monthly mean surface radon concentration and the annual cycle quite well. At those sites where the seasonal variation is not large, the model is able to give a correct magnitude of the annual mean. In East Asia, where radon simulations are rarely reported in literature, detailed analysis shows that our results compare reasonably well with the observations.

    The most evident changes caused by the use of a different convection scheme are found in the vertical distribution of the tracer. The scheme associated with a weaker upward transport gives higher radon concentration up to about 6 km above the surface, and lower values in higher altitudes. In the lower part of the atmosphere results from this scheme does not agree as well with the measurements as the other scheme. Differences from 6 km to the model top are even larger, although we are not yet able to tell which simulation is better due to the lack of observations at such high altitudes.

  19. Establishment of technical prerequisites for cell irradiation experiments with laser-accelerated electrons.

    Science.gov (United States)

    Beyreuther, E; Enghardt, W; Kaluza, M; Karsch, L; Laschinsky, L; Lessmann, E; Nicolai, M; Pawelke, J; Richter, C; Sauerbrey, R; Schlenvoigt, H P; Baumann, M

    2010-04-01

    In recent years, laser-based acceleration of charged particles has rapidly progressed and medical applications, e.g., in radiotherapy, might become feasible in the coming decade. Requirements are monoenergetic particle beams with long-term stable and reproducible properties as well as sufficient particle intensities and a controlled delivery of prescribed doses at the treatment site. Although conventional and laser-based particle accelerators will administer the same dose to the patient, their different time structures could result in different radiobiological properties. Therefore, the biological response to the ultrashort pulse durations and the resulting high peak dose rates of these particle beams have to be investigated. The technical prerequisites, i.e., a suitable cell irradiation setup and the precise dosimetric characterization of a laser-based particle accelerator, have to be realized in order to prepare systematic cell irradiation experiments. The Jena titanium:sapphire laser system (JETI) was customized in preparation for cell irradiation experiments with laser-accelerated electrons. The delivered electron beam was optimized with regard to its spectrum, diameter, dose rate, and dose homogeneity. A custom-designed beam and dose monitoring system, consisting of a Roos ionization chamber, a Faraday cup, and EBT-1 dosimetry films, enables real-time monitoring of irradiation experiments and precise determination of the dose delivered to the cells. Finally, as proof-of-principle experiment cell samples were irradiated using this setup. Laser-accelerated electron beams, appropriate for in vitro radiobiological experiments, were generated with a laser shot frequency of 2.5 Hz and a pulse length of 80 fs. After laser acceleration in the helium gas jet, the electrons were filtered by a magnet, released from the vacuum target chamber, and propagated in air for a distance of 220 mm. Within this distance a lead collimator (aperture of 35 mm) was introduced, leading

  20. Electron microscopic radioautographic studies on macromolecular synthesis in mitochondria of animal cells in aging

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Tetsuji, E-mail: nagata@kowagakuen.ac.j [Shinshu Univ. School of Medicine, Matsumoto (Japan). Dept. of Anatomy and Cell Biology

    2010-07-01

    Study aging changes of intramitochondrial DNA, RNA, protein synthesis of mouse organs during the development and aging, 30 groups of developing and aging mice (3 individuals each), from fetal day 19 to postnatal newborn at day 1, 3, 9, 14 and adult at month 1, 2, 6, 12 to 24, were injected with either {sup 3}H-thymidine, {sup 3}H-uriidine, or {sup 3}H-leucine, sacrificed 1 h later and liver, adrenal, lung and testis tissues observed by electron microscopic radioautography. Accordingly, numbers of mitochondria per cell profile area, numbers of labeled mitochondria and the mitochondrial labeling index labeled with {sup 3}H-labeled precursors showing DNA, RNA, protein synthesis in these cells (hepatocytes, 3 zones of the adrenal cortices - zona glomerulosa, fasciculata and reticularis -, adrenal medullary cells, pulmonary cells and testis cells) were counted per cells and compared among the respective developing and aging groups. The numbers of mitochondria in these cells increased from fetal day 19 to postnatal month 1 and 2. However, the numbers of labeled mitochondria and the labeling indices of intramitochondrial DNA, RNA, protein syntheses incorporating the {sup 3}H-labeled precursors in the described tissue cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. These data support that the activity of intramitochnodrial DNA, RNA, protein syntheses in cells of these tissues increased and decreased by development and aging in mice. The intramitochondrial DNA, RNA and protein syntheses in some other organs were also reviewed and discussed. (author)

  1. Investigating Ceria Nanocrystals Uptake by Glioblastoma Multiforme Cells and its Related Effects: An Electron Microscopy Study

    KAUST Repository

    Aloufi, Bader

    2017-01-22

    Cerium oxide nanoparticles have been utilized widely nowadays in cancer research. It has been suggested by many studies that these nanoparticles are capable of having dual antioxidant behavior in healthy and cancer microenvironment; where in physiological condition, they act as antioxidant and do not affect the healthy cells, while in tumor-like condition; they act as an oxidase, and result in a selective killing for the cancer cells. In this experiment, the interaction of nanoceria with glioblastoma and healthy astrocyte cells was examined, and further correlated with the in vitro cytotoxic effects of various nanoceria concentrations (100 and 300 µg/ml) and exposure times (12, 24, and 48 hours). Electron microscopes were used to investigate the cellular-NPs interactions, and to examine the related cytotoxic effects in combination with trypan blue and propidium iodide viability assays. Our data suggest the following results. First, the two cell lines demonstrated capability of taken up the ceria through endocytosis pathway, where the NPs were recognized engulfed by double membrane vesicles at various regions over the cellular cytoplasm. Secondly, cerium oxide nanoparticles were found to affect the glioblastoma cells, but not so severely the corresponding healthy astrocytes at the various concentrations and incubation times, as revealed by the viability assays and the electron microscopy analysis. Thirdly, the viability of the glioblastoma cells after the treatment displayed a declined trend when increasing the ceria concentrations, but did not show such dependency with regard to the different time points. In all cases, the healthy astrocyte cells showed slight alterations in mitochondrial shape which did not influence their viability. Among the various nanoceria concentrations and exposure times, the most efficient dose of treatment was found to be with a concentration of 300 µg/ml at a time point of 24-hour, where higher reduction on the viability of

  2. Nitrogen doped carbon nanoparticles enhanced extracellular electron transfer for high-performance microbial fuel cells anode.

    Science.gov (United States)

    Yu, Yang-Yang; Guo, Chun Xian; Yong, Yang-Chun; Li, Chang Ming; Song, Hao

    2015-12-01

    Nitrogen doped carbon nanoparticles (NDCN) were applied to modify the carbon cloth anodes of microbial fuel cells (MFCs) inoculated with Shewanella oneidensis MR-1, one of the most well-studied exoelectrogens. Experimental results demonstrated that the use of NDCN increased anodic absorption of flavins (i.e., the soluble electron mediator secreted by S. oneidensis MR-1), facilitating shuttle-mediated extracellular electron transfer. In addition, we also found that NDCN enabled enhanced contact-based direct electron transfer via outer-membrane c-type cytochromes. Taken together, the performance of MFCs with the NDCN-modified anode was enormously enhanced, delivering a maximum power density 3.5 times' higher than that of the MFCs without the modification of carbon cloth anodes.

  3. Effect of cathode electron acceptors on simultaneous anaerobic sulfide and nitrate removal in microbial fuel cell.

    Science.gov (United States)

    Cai, Jing; Zheng, Ping; Mahmood, Qaisar

    2016-01-01

    The current investigation reports the effect of cathode electron acceptors on simultaneous sulfide and nitrate removal in two-chamber microbial fuel cells (MFCs). Potassium permanganate and potassium ferricyanide were common cathode electron acceptors and evaluated for substrate removal and electricity generation. The abiotic MFCs produced electricity through spontaneous electrochemical oxidation of sulfide. In comparison with abiotic MFC, the biotic MFC showed better ability for simultaneous nitrate and sulfide removal along with electricity generation. Keeping external resistance of 1,000 Ω, both MFCs showed good capacities for substrate removal where nitrogen and sulfate were the main end products. The steady voltage with potassium permanganate electrodes was nearly twice that of with potassium ferricyanide. Cyclic voltammetry curves confirmed that the potassium permanganate had higher catalytic activity than potassium ferricyanide. The potassium permanganate may be a suitable choice as cathode electron acceptor for enhanced electricity generation during simultaneous treatment of sulfide and nitrate in MFCs.

  4. Influence of electron injection into 27 cm audio plasma cell on the plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Haleem, N. A.; Ragheb, M. S.; Zakhary, S. G. [Accelerators Department, Nuclear Research Center, AEA, Cairo 13759 (Egypt); El Fiki, S. A.; Nouh, S. A. [Faculty of Science, Ain Shams University, Cairo 11566 (Egypt); El Disoki, T. M. [Faculty of Girls, Ain Shams University, Cairo 11566 (Egypt)

    2013-08-15

    In this article, the plasma is created in a Pyrex tube (L = 27 cm, φ= 4 cm) as a single cell, by a capacitive audio frequency (AF) discharge (f = 10–100 kHz), at a definite pressure of ∼0.2 Torr. A couple of tube linear and deviating arrangements show plasma characteristic conformity. The applied AF plasma and the injection of electrons into two gas mediums Ar and N{sub 2} revealed the increase of electron density at distinct tube regions by one order to attain 10{sup 13}/cm{sup 3}. The electrons temperature and density strengths are in contrast to each other. While their distributions differ along the plasma tube length, they show a decaying sinusoidal shape where their peaks position varies by the gas type. The electrons injection moderates electron temperature and expands their density. The later highest peak holds for the N{sub 2} gas, at electrons injection it changes to hold for the Ar. The sinusoidal decaying density behavior generates electric fields depending on the gas used and independent of tube geometry. The effect of the injected electrons performs a responsive impact on electrons density not attributed to the gas discharge. Analytical tools investigate the interaction of the plasma, the discharge current, and the gas used on the electrodes. It points to the emigration of atoms from each one but for greater majority they behave to a preferred direction. Meanwhile, only in the linear regime, small percentage of atoms still moves in reverse direction. Traces of gas atoms revealed on both electrodes due to sheath regions denote lack of their participation in the discharge current. In addition, atoms travel from one electrode to the other by overcoming the sheaths regions occurring transportation of particles agglomeration from one electrode to the other. The electrons injection has contributed to increase the plasma electron density peaks. These electrons populations have raised the generated electrostatic fields assisting the elemental ions

  5. An Azaacene Derivative as Promising Electron-Transport Layer for Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Gu, Pei-Yang; Wang, Ning; Wu, Anyang; Wang, Zilong; Tian, Miaomiao; Fu, Zhisheng; Sun, Xiao Wei; Zhang, Qichun

    2016-08-05

    It is highly desirable to develop novel n-type organic small molecules as an efficient electron-transport layer (ETL) for the replacement of PCBM to obtain high-performance metal-oxide-free, solution-processed inverted perovskite solar cells (PSCs) because this type of solar cells with a low-temperature and solution-based process would make their fabrication more feasible and practical. In this research, the new azaacene QCAPZ has been synthesized and employed as non-fullerene ETL material for inverted PSCs through a solution-based process without the need for additional dopants or additives. The as-fabricated inverted PSCs show a power conversion efficiency up to 10.26 %. Our results clearly suggest that larger azaacenes could be promising electron-transport materials to achieve high-performance solution-processed inverted PSCs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Beneficial Role of Reduced Graphene Oxide for Electron Extraction in Highly Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Cho, Kyung Taek; Grancini, Giulia; Lee, Yonghui; Konios, Dimitrios; Paek, Sanghyun; Kymakis, Emmanuel; Nazeeruddin, Mohammad Khaja

    2016-11-09

    In this work we systematically investigated the role of reduced graphene oxide (rGO) in hybrid perovskite solar cells (PSCs). By mixing rGO within the mesoporous TiO2 (m-TiO2 ) matrix, highly efficient solar cells with power conversion efficiency values up to 19.54 % were realized. In addition, the boosted beneficial role of rGO with and without Li-treated m-TiO2 is highlighted, improving transport and injection of photoexcited electrons. This combined system may pave the way for further development and optimization of electron transport and collection in high efficiency PSCs. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Particle-in-cell simulations of plasma accelerators and electron-neutral collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bruhwiler, David L.; Giacone, Rodolfo E.; Cary, John R.; Verboncoeur, John P.; Mardahl, Peter; Esarey, Eric; Leemans, W.P.; Shadwick, B.A.

    2001-10-01

    We present 2-D simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented particle-in-cell code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low ({approx}10{sup 16} W/cm{sup 2}) and high ({approx}10{sup 18} W/cm{sup 2}) peak intensity laser pulses are conducted in slab geometry, showing agreement with theory and fluid simulations. Simulations of the E-157 beam wakefield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are conducted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications of XOOPIC required by this work, and summarize the issues relevant to modeling relativistic electron-neutral collisions in a particle-in-cell code.

  8. Silicon Based Solid Oxide Fuel Cell Chip for Portable Consumer Electronics -- Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Alan Ludwiszewski

    2009-06-29

    LSI’s fuel cell uses efficient Solid Oxide Fuel Cell (“SOFC”) technology, is manufactured using Micro Electrical Mechanical System (“MEMS”) fabrication methods, and runs on high energy fuels, such as butane and ethanol. The company’s Fuel Cell on a Chip™ technology enables a form-factor battery replacement for portable electronic devices that has the potential to provide an order-of-magnitude run-time improvement over current batteries. Further, the technology is clean and environmentally-friendly. This Department of Energy funded project focused on accelerating the commercialization and market introduction of this technology through improvements in fuel cell chip power output, lifetime, and manufacturability.

  9. Picoliter Drop-On-Demand Dispensing for Multiplex Liquid Cell Transmission Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Joseph P.; Parent, Lucas R.; Cantlon, Joshua; Eickhoff, Holger; Bared, Guido; Evans, James E.; Gianneschi, Nathan C.

    2016-05-03

    Abstract

    Liquid cell transmission electron microscopy (LCTEM) provides a unique insight into the dynamics of nanomaterials in solution. Controlling the addition of multiple solutions to the liquid cell remains a key hurdle in our ability to increase throughput and to study processes dependent on solution mixing including chemical reactions. Here, we report that a piezo dispensing technique allows for mixing of multiple solutions directly within the viewing area. This technique permits deposition of 50 pL droplets of various aqueous solutions onto the liquid cell window, before assembly of the cell in a fully controlled manner. This proof-of-concept study highlights the great potential of picoliter dispensing in combination with LCTEM for observing nanoparticle mixing in the solution phase and the creation of chemical gradients.

  10. One electron changes everything: a multispecies copper redox shuttle for dye-sensitized solar cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hoffeditz, William L.; Katz, Michael J.; Deria, Pravas; Cutsail, George E.; Pellin, Michael J.; Farha, Omar K.; Hupp, Joseph T.

    2016-02-25

    Dye-sensitized solar cells (DSCs) are an established alternative photovoltaic technology that offers numerous potential advantages in solar energy applications. However, this technology has been limited by the availability of molecular redox couples that are both noncorrosive/nontoxic and do not diminish the performance of the device. In an effort to overcome these shortcomings, a copper-containing redox shuttle derived from 1,8-bis(2'-pyridyl)-3,6-dithiaoctane (PDTO) ligand and the common DSC additive 4-tert-butylpyridine (TBP) was investigated. Electrochemical measurements, single-crystal X-ray diffraction, and absorption and electron paramagnetic resonance spectroscopies reveal that, upon removal of one metal-centered electron, PDTO-enshrouded copper ions completely shed the tetradentate PDTO ligand and replace it with four or more TBP ligands. Thus, the Cu(I) and Cu(II) forms of the electron shuttle have completely different coordination spheres and are characterized by widely differing Cu(II/I) formal potentials and reactivities for forward versus reverse electron transfer. Notably, the coordination-sphere replacement process is fully reversed upon converting Cu(II) back to Cu(I). In cells featuring an adsorbed organic dye and a nano- and mesoparticulate, TiO2-based, photoelectrode, the dual species redox shuttle system engenders performance superior to that obtained with shuttles based on the (II/I) forms of either of the coordination complexes in isolation.

  11. In situ liquid cell electron microscopy of Ag-Au galvanic replacement reactions.

    Science.gov (United States)

    Sutter, Eli A; Sutter, Peter W

    2017-01-19

    Galvanic replacement reactions are important as they transform nanoparticle templates into complex porous and hollow metal or alloy nanostructures with interesting properties for a variety of applications. Real-time liquid cell electron microscopy (LCEM) observations of the transformation of solid nanoparticles into hollow shell and cage bimetallic nanostructures are challenging because the high-energy electron beam strongly affects the galvanic process via species such as aqueous electrons and hydroxyl radicals generated through the radiolysis of water in the liquid cell. As a result the galvanic reactions are modified by the introduction of additional pathways that can decouple the oxidation of the nanoparticles from the reduction of the metal ion complexes in solution. Here we demonstrate that changing the pH of the solution provides an effective approach to alter the balance of radiolysis products. In situ observations of the transformation of Ag nanocubes in Au salt containing neutral and acidic aqueous solutions demonstrate that a lowering of the pH by addition of H2SO4 significantly lessens radical-induced modifications of redox reactions by avoiding the excessive reduction of metal-chloro complexes by aqueous electrons (eaq(-)) and making the process sufficiently slow to be observed. As a result, the different stages of galvanic replacement reactions on nanoparticles can be imaged in real-time by LCEM.

  12. Detection of electron emission as DLTS signal in CdTe solar cells

    Science.gov (United States)

    Ding, Y. M.; Cheng, Z.; Tan, X.; Misra, D.; Delahoy, A. E.; Chin, K. K.

    2016-10-01

    This work identifies an incongruity in the detection of the minority carrier signal in CdTe solar cells during the deep level transient spectroscopy (DLTS) measurement. Use of quasi-Fermi level instead of Fermi level of majority carriers to estimate the probability of emitting carriers seems to correct the ambiguity. During the experiment, signals from minority carrier traps (electron traps) were detected by using a long filling pulse time instead of an electron injection pulse. The DLTS measurements of CdTe solar cells observed a single electron trap with energy level EE1 = 0.47 eV, and two hole traps with energy levels, EH1 = 0.17 eV and EH2 = 0.27 eV. The possibility of any impact from the back contact was excluded, and the phenomenon was clarified by the simulation. It was further observed that when the condition of quasi-Fermi level is considered, the results of calculated probability were significantly different from that of the results that used only Fermi level of majority carriers. The simulations further aided the explanation of the defect behavior in DLTS measurements and the overlapping phenomenon of the capacitance spectrum of hole and electron traps.

  13. CTS and CZTS for solar cells made by pulsed laser deposition and pulsed electron deposition

    DEFF Research Database (Denmark)

    Ettlinger, Rebecca Bolt

    , which make them promising alternatives to the commercially successful solar cell material copper indium gallium diselenide (CIGS). Complementing our group's work on pulsed laser deposition of CZTS, we collaborated with IMEM-CNR in Parma, Italy, to deposit CZTS by pulsed electron deposition for the first...... time. We compared the results of CZTS deposition by PLD at DTU in Denmark to CZTS made by PED at IMEM-CNR, where CIGS solar cells have successfully been fabricated at very low processing temperatures. The main results of this work were as follows: Monoclinic-phase CTS films were made by pulsed laser...

  14. Electron Transfer Mediators for Photoelectrochemical Cells Based on Cu(I Metal Complexes

    Directory of Open Access Journals (Sweden)

    Michele Brugnati

    2007-01-01

    Full Text Available The preparation and the photoelectrochemical characterization of a series of bipyridine and pyridyl-quinoline Cu(I complexes, used as electron transfer mediators in regenerative photoelectrochemical cells, are reported. The best performing mediators produced maximum IPCEs of the order of 35–40%. The J-V curves recorded under monochromatic light showed that the selected Cu(I/(II couples generated higher Vocs and fill factors compared to an equivalent I-/I3- cell, due to a decreased dark current.

  15. Unravelling the structural-electronic impact of arylamine electron-donating antennas on the performances of efficient ruthenium sensitizers for dye-sensitized solar cells

    Science.gov (United States)

    Chen, Wang-Chao; Kong, Fan-Tai; Ghadari, Rahim; Li, Zhao-Qian; Guo, Fu-Ling; Liu, Xue-Peng; Huang, Yang; Yu, Ting; Hayat, Tasawar; Dai, Song-Yuan

    2017-04-01

    We report a systematic research to understand the structural-electronic impact of the arylamine electron-donating antennas on the performances of the ruthenium complexes for dye-sensitized solar cells. Three ruthenium complexes functionalized with different arylamine electron-donating antennas (N,N-diethyl-aniline in RC-31, julolidine in RC-32 and N,N-dibenzyl-aniline in RC-36) are designed and synthesized. The photoelectric properties of RC dyes exhibit apparent discrepancy, which are ascribed to different structural nature and electronic delocalization ability of these arylamine electron-donating system. In conjunction with TiO2 microspheres photoanode and a typical coadsorbent DPA, the devices sensitized by RC-36 achieve the best conversion efficiency of 10.23%. The UV-Vis absorption, electrochemical measurement, incident photon-to-current conversion efficiency and transient absorption spectra confirm that the excellent performance of RC-36 is induced by synergistically structural-electronic impacts from enhanced absorption capacity and well-tuned electronic characteristics. These observations provide valuable insights into the molecular engineering methodology based on fine tuning structural-electronic impact of electron-donating antenna in efficient ruthenium sensitizers.

  16. TiO2 Electron Transport Bilayer for Highly Efficient Planar Perovskite Solar Cell.

    Science.gov (United States)

    Lu, Hao; Tian, Wei; Gu, Bangkai; Zhu, Yayun; Li, Liang

    2017-08-22

    In planar perovskite solar cells, it is vital to engineer the extraction and recombination of electron-hole pairs at the electron transport layer/perovskite interface for obtaining high performance. This study reports a novel titanium oxide (TiO2 ) bilayer with different Fermi energy levels by combing atomic layer deposition and spin-coating technique. Energy band alignments of TiO2 bilayer can be modulated by controlling the deposition order of layers. The TiO2 bilayer based perovskite solar cells are highly efficient in carrier extraction, recombination suppression, and defect passivation, and thus demonstrate champion efficiencies up to 16.5%, presenting almost 50% enhancement compared to the TiO2 single layer based counterparts. The results suggest that the bilayer with type II band alignment as electron transport layers provides an efficient approach for constructing high-performance planar perovskite solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Modeling particle-induced electron emission in a simplified plasma Test Cell

    Energy Technology Data Exchange (ETDEWEB)

    Giuliano, Paul N.; Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2013-03-21

    Particle-induced electron emission (PIE) is modeled in a simplified, well-characterized plasma Test Cell operated at UCLA. In order for PIE to be a useful model in this environment, its governing equations are first reduced to lower-order models which can be implemented in a direct simulation Monte Carlo and Particle-in-Cell framework. These reduced-order models are described in full and presented as semi-empirical models. The models are implemented to analyze the interaction of low- and high-energy ({approx}1-2 keV) xenon ions and atoms with the stainless steel electrodes of the Test Cell in order to gain insight into the emission and transport of secondary electrons. Furthermore, there is a lack of data for xenon-stainless steel atom- and ion-surface interactions for similar environments. Using experimental data as a reference, both total yields and emitted electron energy distribution functions can be deduced by observing sensitivities of current collection results to these numerical models and their parameters.

  18. Enhancing Intrinsic Stability of Hybrid Perovskite Solar Cell by Strong, yet Balanced, Electronic Coupling

    Science.gov (United States)

    El-Mellouhi, Fedwa; Bentria, El Tayeb; Rashkeev, Sergey N.; Kais, Sabre; Alharbi, Fahhad H.

    2016-07-01

    In the past few years, the meteoric development of hybrid organic–inorganic perovskite solar cells (PSC) astonished the community. The efficiency has already reached the level needed for commercialization; however, the instability hinders its deployment on the market. Here, we report a mechanism to chemically stabilize PSC absorbers. We propose to replace the widely used methylammonium cation (CH3NH3+) by alternative molecular cations allowing an enhanced electronic coupling between the cation and the PbI6 octahedra while maintaining the band gap energy within the suitable range for solar cells. The mechanism exploits establishing a balance between the electronegativity of the materials’ constituents and the resulting ionic electrostatic interactions. The calculations demonstrate the concept of enhancing the electronic coupling, and hence the stability, by exploring the stabilizing features of CH3PH3+, CH3SH2+, and SH3+ cations, among several other possible candidates. Chemical stability enhancement hence results from a strong, yet balanced, electronic coupling between the cation and the halides in the octahedron. This shall unlock the hindering instability problem for PSCs and allow them to hit the market as a serious low-cost competitor to silicon based solar cell technologies.

  19. Enhancing Intrinsic Stability of Hybrid Perovskite Solar Cell by Strong, yet Balanced, Electronic Coupling

    Science.gov (United States)

    El-Mellouhi, Fedwa; Bentria, El Tayeb; Rashkeev, Sergey N.; Kais, Sabre; Alharbi, Fahhad H.

    2016-01-01

    In the past few years, the meteoric development of hybrid organic–inorganic perovskite solar cells (PSC) astonished the community. The efficiency has already reached the level needed for commercialization; however, the instability hinders its deployment on the market. Here, we report a mechanism to chemically stabilize PSC absorbers. We propose to replace the widely used methylammonium cation (CH3NH3+) by alternative molecular cations allowing an enhanced electronic coupling between the cation and the PbI6 octahedra while maintaining the band gap energy within the suitable range for solar cells. The mechanism exploits establishing a balance between the electronegativity of the materials’ constituents and the resulting ionic electrostatic interactions. The calculations demonstrate the concept of enhancing the electronic coupling, and hence the stability, by exploring the stabilizing features of CH3PH3+, CH3SH2+, and SH3+ cations, among several other possible candidates. Chemical stability enhancement hence results from a strong, yet balanced, electronic coupling between the cation and the halides in the octahedron. This shall unlock the hindering instability problem for PSCs and allow them to hit the market as a serious low-cost competitor to silicon based solar cell technologies. PMID:27457130

  20. A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Gleb Sorohhov

    2015-06-01

    Full Text Available Two new photosensitizers featured with a cyanoacrylic acid electron acceptor (A and a hybrid electron donor (D of cyclopentadithiophene and dithiafulvenyl, either directly linked or separated by a phenyl ring, were synthesized and characterized. Both of them undergo two reversible oxidations and strongly absorb in the visible spectral region due to a photo-induced intramolecular charge-transfer (ICT transition. To a great extent, the electronic interaction between the D and A units is affected by the presence of a phenyl spacer. Without a phenyl ring, the D unit appears more difficult to oxidize due to a strong electron-withdrawing effect of the A moiety. In sharp contrast, the insertion of the phenyl ring between the D and A units leads to a broken π-conjugation and therefore, the oxidation potentials remain almost unchanged compared to those of an analogue without the A group, suggesting that the electronic coupling between D and A units is relatively weak. As a consequence, the lowest-energy absorption band shows a slight hypsochromic shift upon the addition of the phenyl spacer, indicative of an increased HOMO–LUMO gap. In turn, the direct linkage of D and A units leads to an effective π-conjugation, thus substantially lowering the HOMO–LUMO gap. Moreover, the application in dye-sensitized solar cells was investigated, showing that the power conversion efficiency increases by the insertion of the phenyl unit.

  1. A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells.

    Science.gov (United States)

    Sorohhov, Gleb; Yi, Chenyi; Grätzel, Michael; Decurtins, Silvio; Liu, Shi-Xia

    2015-01-01

    Two new photosensitizers featured with a cyanoacrylic acid electron acceptor (A) and a hybrid electron donor (D) of cyclopentadithiophene and dithiafulvenyl, either directly linked or separated by a phenyl ring, were synthesized and characterized. Both of them undergo two reversible oxidations and strongly absorb in the visible spectral region due to a photo-induced intramolecular charge-transfer (ICT) transition. To a great extent, the electronic interaction between the D and A units is affected by the presence of a phenyl spacer. Without a phenyl ring, the D unit appears more difficult to oxidize due to a strong electron-withdrawing effect of the A moiety. In sharp contrast, the insertion of the phenyl ring between the D and A units leads to a broken π-conjugation and therefore, the oxidation potentials remain almost unchanged compared to those of an analogue without the A group, suggesting that the electronic coupling between D and A units is relatively weak. As a consequence, the lowest-energy absorption band shows a slight hypsochromic shift upon the addition of the phenyl spacer, indicative of an increased HOMO-LUMO gap. In turn, the direct linkage of D and A units leads to an effective π-conjugation, thus substantially lowering the HOMO-LUMO gap. Moreover, the application in dye-sensitized solar cells was investigated, showing that the power conversion efficiency increases by the insertion of the phenyl unit.

  2. Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics.

    Science.gov (United States)

    Woehl, T J; Abellan, P

    2017-02-01

    We present a critical review of methods for defining the chemical environment during liquid cell electron microscopy investigation of electron beam induced nanomaterial growth and degradation. We draw from the radiation chemistry and liquid cell electron microscopy literature to present solution chemistry and electron beam-based methods for selecting the radiolysis products formed and their relative amount during electron irradiation of liquid media in a transmission electron microscope. We outline various methods for establishing net oxidizing or net reducing reaction environments and propose solvents with minimal overall production of radicals under the electron beam. Exemplary liquid cell electron microscopy experiments in the fields of nanoparticle nucleation, growth, and degradation along with recommendations for best practices and experimental parameters are reported. We expect this review will provide researchers with a useful toolkit for designing general chemistry and materials science liquid cell electron microscopy experiments by 'directing' the effect of the electron beam to understand fundamental mechanisms of dynamic nanoscale processes as well as minimizing radiation damage to samples. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  3. Outward electron transfer by Saccharomyces cerevisiae monitored with a bi-cathodic microbial fuel cell-type activity sensor.

    Science.gov (United States)

    Ducommun, Raphaël; Favre, Marie-France; Carrard, Delphine; Fischer, Fabian

    2010-03-01

    A Janus head-like bi-cathodic microbial fuel cell was constructed to monitor the electron transfer from Saccharomyces cerevisiae to a woven carbon anode. The experiments were conducted during an ethanol cultivation of 170 g/l glucose in the presence and absence of yeast-peptone medium. First, using a basic fuel-cell type activity sensor, it was shown that yeast-peptone medium contains electroactive compounds. For this purpose, 1% solutions of soy peptone and yeast extract were subjected to oxidative conditions, using a microbial fuel cell set-up corresponding to a typical galvanic cell, consisting of culture medium in the anodic half-cell and 0.5 M K(3)Fe(CN)(6) in the cathodic half-cell. Second, using a bi-cathodic microbial fuel cell, it was shown that electrons were transferred from yeast cells to the carbon anode. The participation of electroactive compounds in the electron transport was separated as background current. This result was verified by applying medium-free conditions, where only glucose was fed, confirming that electrons are transferred from yeast cells to the woven carbon anode. Knowledge about the electron transfer through the cell membrane is of importance in amperometric online monitoring of yeast fermentations and for electricity production with microbial fuel cells.

  4. Particle-in-cell simulation of electron trajectories and irradiation uniformity in an annular cathode high current pulsed electron beam source

    Science.gov (United States)

    Jiang, Wei; Wang, Langping; Zhou, Guangxue; Wang, Xiaofeng

    2017-02-01

    In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 mm and -15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source.

  5. An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery

    Science.gov (United States)

    Aglzim, El-Hassane; Rouane, Amar; El-Moznine, Reddad

    2007-01-01

    In this paper we present an inexpensive electronic measurement instrumentation developed in our laboratory, to measure and plot the impedance of a loaded fuel cell or battery. Impedance measurements were taken by using the load modulation method. This instrumentation has been developed around a VXI system stand which controls electronic cards. Software under Hpvee® was developed for automatic measurements and the layout of the impedance of the fuel cell on load. The measurement environment, like the ambient temperature, the fuel cell temperature, the level of the hydrogen, etc…, were taken with several sensors that enable us to control the measurement. To filter the noise and the influence of the 50Hz, we have implemented a synchronous detection which filters in a very narrow way around the useful signal. The theoretical result obtained by a simulation under Pspice® of the method used consolidates the choice of this method and the possibility of obtaining correct and exploitable results. The experimental results are preliminary results on a 12V vehicle battery, having an inrush current of 330A and a capacity of 40Ah (impedance measurements on a fuel cell are in progress, and will be the subject of a forthcoming paper). The results were plotted at various nominal voltages of the battery (12.7V, 10V, 8V and 5V) and with two imposed currents (0.6A and 4A). The Nyquist diagram resulting from the experimental data enable us to show an influence of the load of the battery on its internal impedance. The similitude in the graph form and in order of magnitude of the values obtained (both theoretical and practical) enables us to validate our electronic measurement instrumentation. One of the future uses for this instrumentation is to integrate it with several control sensors, on a vehicle as an embedded system to monitor the degradation of fuel cell membranes.

  6. Electron drift-mobility measurements in polycrystalline CuIn1-xGaxSe2 solar cells

    Science.gov (United States)

    Dinca, S. A.; Schiff, E. A.; Shafarman, W. N.; Egaas, B.; Noufi, R.; Young, D. L.

    2012-03-01

    We report photocarrier time-of-flight measurements of electron drift mobilities for the p-type CuIn1-xGaxSe2 films incorporated in solar cells. The electron mobilities range from 0.02 to 0.05 cm2/Vs and are weakly temperature-dependent from 100-300 K. These values are lower than the range of electron Hall mobilities (2-1100 cm2/Vs) reported for n-type polycrystalline thin films and single crystals. We propose that the electron drift mobilities are properties of disorder-induced mobility edges and discuss how this disorder could increase cell efficiencies.

  7. Reversible electron-hole separation in a hot carrier solar cell

    Science.gov (United States)

    Linke, Heiner

    Hot-carrier solar cells are envisioned to utilize energy filtering to extract power from photogenerated electron-hole pairs before they thermalize with the lattice, and thus potentially offer higher power conversion efficiency compared to conventional, single absorber solar cells. The efficiency of hot-carrier solar cells can be expected to strongly depend on the details of the energy filtering process, a relationship which to date has not been satisfactorily explored. Here, we establish the conditions under which electron-hole separation in hot-carrier solar cells can occur reversibly, that is, at maximum energy conversion efficiency. We find that, under specific conditions, the energy conversion efficiency of a hot-carrier solar cell can exceed the Carnot limit set by the intra-device temperature gradient alone, due to the additional contribution of the quasi-Fermi level splitting in the absorber. To achieve this, we consider a highly selective energy filter such as a quantum dot embedded into a one-dimensional conductor. We also establish that the open-circuit voltage of a hot-carrier solar cell is not limited by the band gap of the absorber, due to the additional thermoelectric contribution to the voltage. Additionally, we find that a hot-carrier solar cell can be operated in reverse as a thermally driven solid-state light emitter. In addition this theoretical analysis, I will also report on first experimental results in a nanowire-based energy filter device. Ref: S Limpert, S Bremner, and H Linke, New J. Phys 17, 095004 (2015)

  8. Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines

    Science.gov (United States)

    Yu, Vicky; Rahimy, Mehran; Korrapati, Avinaash; Xuan, Yinan; Zou, Angela E.; Krishnan, Aswini R.; Tsui, Tzuhan; Aguilera, Joseph A.; Advani, Sunil; Crotty Alexander, Laura E.; Brumund, Kevin T.; Wang-Rodriguez, Jessica

    2016-01-01

    Objectives Evaluate the cytotoxicity and genotoxicity of short- and long-term e-cigarette vapor exposure on a panel of normal epithelial and head and neck squamous cell carcinoma (HNSCC) cell lines. Materials and Methods HaCaT, UMSCC10B, and HN30 were treated with nicotine-containing and nicotine-free vapor extract from two popular e-cigarette brands for periods ranging from 48 hours to 8 weeks. Cytotoxicity was assessed using Annexin V flow cytometric analysis, trypan blue exclusion, and clonogenic assays. Genotoxicity in the form of DNA strand breaks was quantified using the neutral comet assay and γ-H2AX immunostaining. Results E-cigarette-exposed cells showed significantly reduced cell viability and clonogenic survival, along with increased rates of apoptosis and necrosis, regardless of e-cigarette vapor nicotine content. They also exhibited significantly increased comet tail length and accumulation of γ-H2AX foci, demonstrating increased DNA strand breaks. Conclusion E-cigarette vapor, both with and without nicotine, is cytotoxic to epithelial cell lines and is a DNA strand break-inducing agent. Further assessment of the potential carcinogenic effects of e-cigarette vapor is urgently needed. PMID:26547127

  9. Native immunogold labeling of cell surface proteins and viral glycoproteins for cryo-electron microscopy and cryo-electron tomography applications.

    Science.gov (United States)

    Yi, Hong; Strauss, Joshua D; Ke, Zunlong; Alonas, Eric; Dillard, Rebecca S; Hampton, Cheri M; Lamb, Kristen M; Hammonds, Jason E; Santangelo, Philip J; Spearman, Paul W; Wright, Elizabeth R

    2015-10-01

    Numerous methods have been developed for immunogold labeling of thick, cryo-preserved biological specimens. However, most of the methods are permutations of chemical fixation and sample sectioning, which select and isolate the immunolabeled region of interest. We describe a method for combining immunogold labeling with cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET) of the surface proteins of intact mammalian cells or the surface glycoproteins of assembling and budding viruses in the context of virus-infected mammalian cells cultured on EM grids. In this method, the cells were maintained in culture media at physiologically relevant temperatures while sequentially incubated with the primary and secondary antibodies. Subsequently, the immunogold-labeled specimens were vitrified and observed under cryo-conditions in the transmission electron microscope. Cryo-EM and cryo-ET examination of the immunogold-labeled cells revealed the association of immunogold particles with the target antigens. Additionally, the cellular structure was unaltered by pre-immunolabeling chemical fixation and retained well-preserved plasma membranes, cytoskeletal elements, and macromolecular complexes. We think this technique will be of interest to cell biologists for cryo-EM and conventional studies of native cells and pathogen-infected cells.

  10. Unconventional Specimen Preparation Techniques Using High Resolution Low Voltage Field Emission Scanning Electron Microscopy to Study Cell Motility, Host Cell Invasion, and Internal Cell Structures in Toxoplasma gondii

    Science.gov (United States)

    Schatten, Heide; Ris, Hans

    2002-04-01

    Apicomplexan parasites employ complex and unconventional mechanisms for cell locomotion, host cell invasion, and cell division that are only poorly understood. While immunofluorescence and conventional transmission electron microscopy have been used to answer questions about the localization of some cytoskeletal proteins and cell organelles, many questions remain unanswered, partly because new methods are needed to study the complex interactions of cytoskeletal proteins and organelles that play a role in cell locomotion, host cell invasion, and cell division. The choice of fixation and preparation methods has proven critical for the analysis of cytoskeletal proteins because of the rapid turnover of actin filaments and the dense spatial organization of the cytoskeleton and its association with the complex membrane system. Here we introduce new methods to study structural aspects of cytoskeletal motility, host cell invasion, and cell division of Toxoplasma gondii, a most suitable laboratory model that is representative of apicomplexan parasites. The novel approach in our experiments is the use of high resolution low voltage field emission scanning electron microscopy (LVFESEM) combined with two new specimen preparation techniques. The first method uses LVFESEM after membrane extraction and stabilization of the cytoskeleton. This method allows viewing of actin filaments which had not been possible with any other method available so far. The second approach of imaging the parasite's ultrastructure and interactions with host cells uses semithick sections (200 nm) that are resin de-embedded (Ris and Malecki, 1993) and imaged with LVFESEM. This method allows analysis of structural detail in the parasite before and after host cell invasion and interactions with the membrane of the parasitophorous vacuole as well as parasite cell division.

  11. Electron transfer at the cell-uranium interface in Geobacter spp.

    Science.gov (United States)

    Reguera, Gemma

    2012-12-01

    The in situ stimulation of Fe(III) oxide reduction in the subsurface stimulates the growth of Geobacter spp. and the precipitation of U(VI) from groundwater. As with Fe(III) oxide reduction, the reduction of uranium by Geobacter spp. requires the expression of their conductive pili. The pili bind the soluble uranium and catalyse its extracellular reductive precipitation along the pili filaments as a mononuclear U(IV) complexed by carbon-containing ligands. Although most of the uranium is immobilized by the pili, some uranium deposits are also observed in discreet regions of the outer membrane, consistent with the participation of redox-active foci, presumably c-type cytochromes, in the extracellular reduction of uranium. It is unlikely that cytochromes released from the outer membrane could associate with the pili and contribute to the catalysis, because scanning tunnelling microscopy spectroscopy did not reveal any haem-specific electronic features in the pili, but, rather, showed topographic and electronic features intrinsic to the pilus shaft. Pili not only enhance the rate and extent of uranium reduction per cell, but also prevent the uranium from traversing the outer membrane and mineralizing the cell envelope. As a result, pili expression preserves the essential respiratory activities of the cell envelope and the cell's viability. Hence the results support a model in which the conductive pili function as the primary mechanism for the reduction of uranium and cellular protection in Geobacter spp.

  12. Cooperative Tin Oxide Fullerene Electron Selective Layers for High-Performance Planar Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Weijun; Zhao, Dewei; Xiao, Chuanxiao; Wang, Changlei; Cimaroli, Alexander J.; Grice, Corey R.; Yang, Mengjin; Li, Zhen; Jiang, Chun-Sheng; Al-Jassim, Mowafak; Zhu, Kai; Kanatzidis, Mercouri G.; Fang, Guojia; Yan, Yanfa

    2016-10-07

    Both tin oxide (SnO2) and fullerenes have been reported as electron selective layers (ESLs) for producing efficient lead halide perovskite solar cells. Here, we report that SnO2 and fullerenes can work cooperatively to further boost the performance of perovskite solar cells. We find that fullerenes can be redissolved during perovskite deposition, allowing ultra-thin fullerenes to be retained at the interface and some dissolved fullerenes infiltrate into perovskite grain boundaries. The SnO2 layer blocks holes effectively; whereas, the fullerenes promote electron transfer and passivate both the SnO2/perovskite interface and perovskite grain boundaries. With careful device optimization, the best-performing planar perovskite solar cell using a fullerene passivated SnO2 ESL has achieved a steady-state efficiency of 17.75% and a power conversion efficiency of 19.12% with an open circuit voltage of 1.12 V, a short-circuit current density of 22.61 mA cm-2, and a fill factor of 75.8% when measured under reverse voltage scanning. We find that the partial dissolving of fullerenes during perovskite deposition is the key for fabricating high-performance perovskite solar cells based on metal oxide/fullerene ESLs.

  13. Hepatic progenitor cells in human liver cirrhosis:Immunohistochemical,electron microscopic and immunofluorencence confocal microscopic findings

    Institute of Scientific and Technical Information of China (English)

    Jia-Cheng Xiao; Xiao-Long Jin; Peter Ruck; Anne Adam; Edwin Kaiserling

    2004-01-01

    AIM: To investigate whether hepatic progenitor cells (HPC),that reveal the features of oval cells in rodents and small epithelial cells (SEC) in certain human liver disease, were also found in human liver cirrhosis (HLC).METHODS: Surgical liver specimens from 20 cases of hepatitis B virus-positive HLC (15 cases containing hepatocellular carcinoma) were investigated by light microscopic immunohistochemistry (LM-IHC). Among them specimens from 15 cases were investigated by electron microscopy (EM)and those from 5 cases by immunofluorencence confocal laser scanning microscopy (ICLSM). Antibodies against cytokeratin 7 and albumin were used and single and/or double labelling were performed respectively.RESULTS: LM-IHC showed that at the margins of regenerating nodules and in the fibrous septae, a small number of cells in the proliferating bile ductules were positive for CK7 and albumin. At the EM level these HPC were morphologically similar to the SEC described previously, and also similar to the oval cells seen in experimental hepatocarcinogenesis.They were characterized by their small size, oval shape, a high nucleus/cytoplasm ratio, a low organelle content in cytoplasm, and existence of tonofilaments and intercellular junctions. ICLSM revealed that HPC expressed both cytokeratin 7 and albumin.CONCLUSION: HPC with ultrastructural and immunophenotypical features of oval cells, i.e., hepatic stem cell-like cells as noted in other liver diseases, were found in HLC. These findings further support the hypothesis that bipotent hepatic stem cells, that may give rise to biliary epithelial cells and hepatocytes, exist in human livers.

  14. Advantages of indium-tin oxide-coated glass slides in correlative scanning electron microscopy applications of uncoated cultured cells.

    NARCIS (Netherlands)

    Pluk, H.; Stokes, D.J.; Lich, B.; Wieringa, B.; Fransen, J.A.M.

    2009-01-01

    A method of direct visualization by correlative scanning electron microscopy (SEM) and fluorescence light microscopy of cell structures of tissue cultured cells grown on conductive glass slides is described. We show that by growing cells on indium-tin oxide (ITO)-coated glass slides, secondary elect

  15. High-speed counting and sizing of cells in an impedance flow microcytometer with compact electronic instrumentation

    DEFF Research Database (Denmark)

    Castillo-Fernandez, Oscar; Rodriguez-Trujíllo, Romén; Gomila, Gabriel

    2014-01-01

    Here we describe a high-throughput impedance flow cytometer on a chip. This device was built using compact and inexpensive electronic instrumentation. The system was used to count and size a mixed cell sample containing red blood cells and white blood cells. It demonstrated a counting capacity of...

  16. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Sathyanarayana, E-mail: asharao76@gmail.com; Rao, Asha, E-mail: asharao76@gmail.com [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  17. Ice formation and development in aged, wintertime cumulus over the UK: observations and modelling

    Science.gov (United States)

    Crawford, I.; Bower, K. N.; Choularton, T. W.; Dearden, C.; Crosier, J.; Westbrook, C.; Capes, G.; Coe, H.; Connolly, P. J.; Dorsey, J. R.; Gallagher, M. W.; Williams, P.; Trembath, J.; Cui, Z.; Blyth, A.

    2012-06-01

    In situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of a line of small cumulus clouds, using Radar and Lidar, as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE) project. A narrow but extensive line (~100 km long) of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than -8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN) numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed, near cloud top, temperatures (-7.5 °C). The role of mineral dust particles, consistent with concentrations observed near the surface, acting as high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L-1) could be produced by secondary ice particle production providing the observed small amount of primary ice (about 0.01 L-1) was present to initiate it. This emphasises the need to understand primary ice formation in slightly supercooled clouds. It is shown using simple calculations that the Hallett-Mossop process (HM) is the likely source of the secondary ice. Model simulations of the case study were performed with the Aerosol Cloud and Precipitation Interactions Model (ACPIM). These parcel model investigations confirmed the HM process to be a very important mechanism for producing the observed high ice concentrations. A key step in generating the high concentrations was the process of collision and coalescence of rain drops, which once formed fell rapidly through the cloud, collecting ice particles which caused them to freeze and form instant large riming particles. The

  18. Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime

    Directory of Open Access Journals (Sweden)

    K. Pistone

    2015-10-01

    Full Text Available There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood, as changes in atmospheric conditions due to aerosol may change the expected magnitude of indirect effects by altering cloud properties in unexpected ways. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season. In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements of atmospheric precipitable water vapor and the liquid water path (LWP of trade cumulus clouds were made, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol. Here we present evidence of a positive correlation between aerosol and cloud LWP which becomes clear after the data are filtered to control for the natural meteorological variability in the region. We then use the aircraft and ground observatory measurements to explore the mechanisms behind the observed aerosol–LWP correlation. We determine that increased boundary-layer humidity lowering the cloud base is responsible for the observed increase in cloud liquid water. Large-scale analysis indicates that high pollution cases originate with a highly-polluted boundary layer air mass approaching the observatory from a northwesterly direction. This polluted mass exhibits higher temperatures and humidity than the clean case, the former of which may be attributable to heating due to aerosol absorption of solar radiation over the subcontinent. While high temperature conditions dispersed along

  19. A Regulation of Tropical Climate by Radiative Cooling as Simulated in a Cumulus Ensemble Model

    Science.gov (United States)

    Sui, Chung-Hsiung; Lau, K.-M.; Li, X.; Chou, M.-D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Responses of tropical atmosphere to low-boundary forcing are investigated in a 2-D cumulus ensemble model (CEM) with an imposed warm-pool and cold-pool SST contrast (deltaSST). The domain-mean vertical motion is constrained to produce heat sink and moisture source as in the observed tropical climate. In a series of experiments, the warm pool SST is specified at different values while the cold pool SST is specified at 26 C. The strength of the circulation increases with increasing deltaSST until deltaSST reaches 3.5 C, and remains unchanged as deltaSST exceeds 3.5 C. The regulation of tropical convection by zonal SST gradient is constrained by the radiative cooling over the cold pool. For deltaSST less than 3.5 C, an enhanced subsidence warming is balanced by a reduced condensation heating over the cold pool. For deltaSST greater than 3.5 C, the subsidence regime expands over the entire cold pool where no condensation heating exist so that a further enhanced subsidence warming can no longer be sustained. The above regulation mechanism is also evident in the change of energy at the top of the atmosphere (TOA) that is dominated by cloud and water vapor greenhouse effect (c (sub LW)) and G (sub clear). The change in shortwave radiation at TOA is largely cancelled between the warm pool and cold pool, likely due to the same imposed vertical motion in our experiments. For deltaSST less than 3.5 C, an increase of deltaSST is associated with a large increase in c (sub Lw) due to increased total clouds in response to enhanced SST-induced circulation. For deltaSST greater than 3.5 C, clouds over the warm pool decrease with increasing SST, and the change in c (sub LW) is much smaller. In both dSST regimes, the change in CLW is larger than the change in G(sub clear) which is slightly negative. However, in the case of uniform warming (deltaSST=0), DeltaG(sub clear), is positive, approximately 5 W per square meters per degree change of SST.

  20. Sensitivity of Precipitation over China to Diff erent Cumulus Parameterization Schemes in RegCM4

    Institute of Scientific and Technical Information of China (English)

    张少波; 吕世华; 鲍艳; 马迪

    2015-01-01

    The eff ect of diff erent cumulus parameterization schemes (CPSs) on precipitation over China is investi-gated by using the International Centre for Theoretical Physics (ICTP) Regional Climate Model version 4.3 (RegCM-4.3) coupled with the land surface model BATS1e (Biosphere-Atmosphere Transfer Scheme version 1e). The ERA-interim data are utilized to drive a group of simulations over a 31-yr period from September 1982 to December 2012. Two typically sensitive regions, i.e., the eastern Tibetan Plateau (TP; 29◦–38◦N, 90◦–100◦E) and eastern China (EC; 26◦–32◦N, 110◦–120◦E), are focused on. The results show that all the CPSs have well reproduced the spatial distribution of annual precipitation in China. The simulation with the Emanuel scheme shows an overall overestimation of precipitation in China, diff erent from the other three CPSs which only overestimate over northern and northwestern China but underestimate over southern China. Seasonally, the Tiedtke scheme shows the smallest overestimation in winter and summer, and the best simulation of the annual variance of precipitation. Interannual variations of precipitation among the four CPSs are generally simulated better in summer than in winter, and better for entire China than in the subregions of TP and EC. The precipitation trend is simulated better over EC than over TP, and better in summer than in winter. An overestimate (underestimate) of the East Asian summer monsoon index (EASMI) exists in the simulations with the Grell and the Emanuel (the Kuo and the Tiedtke) schemes. The smallest EASMI bias in the Tiedtke simulation could explain its small precipitation bias. A negative correlation between the EASMI and summer precipitation over the middle and lower reaches of Yangtze River is found in the Grell and the Emanuel simulations, but was missed by the simulations using the Kuo and the Tiedtke schemes.

  1. The Goddard Cumulus Ensemble Model (GCE): Improvements and Applications for Studying Precipitation Processes

    Science.gov (United States)

    Tao, Wei-Kuo; Lang, Stephen E.; Zeng, Xiping; Li, Xiaowen; Matsui, Toshi; Mohr, Karen; Posselt, Derek; Chern, Jiundar; Peters-Lidard, Christa; Norris, Peter M.; Kang, In-Sik; Choi, Ildae; Hou, Arthur; Lau, K.-M.; Yang, Young-Min

    2014-01-01

    Convection is the primary transport process in the Earth's atmosphere. About two-thirds of the Earth's rainfall and severe floods derive from convection. In addition, two-thirds of the global rain falls in the tropics, while the associated latent heat release accounts for three-fourths of the total heat energy for the Earth's atmosphere. Cloud-resolving models (CRMs) have been used to improve our understanding of cloud and precipitation processes and phenomena from micro-scale to cloud-scale and mesoscale as well as their interactions with radiation and surface processes. CRMs use sophisticated and realistic representations of cloud microphysical processes and can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems. CRMs also allow for explicit interaction between clouds, outgoing longwave (cooling) and incoming solar (heating) radiation, and ocean and land surface processes. Observations are required to initialize CRMs and to validate their results. The Goddard Cumulus Ensemble model (GCE) has been developed and improved at NASA/Goddard Space Flight Center over the past three decades. It is amulti-dimensional non-hydrostatic CRM that can simulate clouds and cloud systems in different environments. Early improvements and testing were presented in Tao and Simpson (1993) and Tao et al. (2003a). A review on the application of the GCE to the understanding of precipitation processes can be found in Simpson and Tao (1993) and Tao (2003). In this paper, recent model improvements (microphysics, radiation and land surface processes) are described along with their impact and performance on cloud and precipitation events in different geographic locations via comparisons with observations. In addition, recent advanced applications of the GCE are presented that include understanding the physical processes responsible for diurnal variation, examining the impact of aerosols (cloud condensation nuclei or CCN and ice nuclei or IN) on

  2. Mapping boron in silicon solar cells using electron energy-loss spectroscopy

    DEFF Research Database (Denmark)

    Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p...... in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Schönbächler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. Büchel, M....... Hashikawa, K. Kajiwara, T. Yaguchi, M. Konno, H. Mori, Applied Physics Express 1 (2008) 074001 [5] V. Olevano, L. Reining, Physical Review Letters 86 (2001) 5962...

  3. Interfacial electron transfer of Shewanella putrefaciens enhanced by nanoflaky nickel oxide array in microbial fuel cells

    Science.gov (United States)

    Qiao, Yan; Wu, Xiao-Shuai; Li, Chang Ming

    2014-11-01

    A uniform nanoflaky nickel oxide (NiO) array is constructed on carbon cloth via optimized conditions, and further employed as an anode in Shewanella putrefaciens (S. putrefaciens) microbial fuel cells (MFCs). Results indicate that the NiO nanoflakes/carbon cloth anode significantly improves the MFC performance in comparison to the unmodified carbon cloth, delivering about three times higher power density. This attributes to an enhanced interfacial electron transfer rate between bacteria cell and nanoflaky NiO array-modified carbon fiber and improved adhesion of bacteria cells on the modified carbon fiber for more active reaction centers. Considering the facile synthesis process, low cost and long discharging lifetime, this NiO/carbon cloth anode could be very promising to be applied for high performance, large scale MFCs.

  4. Detecting particles with cell phones: the Distributed Electronic Cosmic-ray Observatory

    CERN Document Server

    Vandenbroucke, Justin; Karn, Peter; Meehan, Matthew; Plewa, Matthew; Ruggles, Tyler; Schultz, David; Peacock, Jeffrey; Simons, Ariel Levi

    2015-01-01

    In 2014 the number of active cell phones worldwide for the first time surpassed the number of humans. Cell phone camera quality and onboard processing power (both CPU and GPU) continue to improve rapidly. In addition to their primary purpose of detecting photons, camera image sensors on cell phones and other ubiquitous devices such as tablets, laptops and digital cameras can detect ionizing radiation produced by cosmic rays and radioactive decays. While cosmic rays have long been understood and characterized as a nuisance in astronomical cameras, they can also be identified as a signal in idle camera image sensors. We present the Distributed Electronic Cosmic-ray Observatory (DECO), a platform for outreach and education as well as for citizen science. Consisting of an app and associated database and web site, DECO harnesses the power of distributed camera image sensors for cosmic-ray detection.

  5. Understanding the Role of the Electron-Transport Layer in Highly Efficient Planar Perovskite Solar Cells.

    Science.gov (United States)

    Liu, Jiang; Wang, Gang; Luo, Kun; He, Xulin; Ye, Qinyan; Liao, Cheng; Mei, Jun

    2017-03-17

    Solar cells based on perovskite absorbers are rapidly emerging as attractive candidates for photovoltaics development. Understanding the role of the electron-transport layer (ETL) is very important to obtain highly efficient perovskite solar cells. Herein, the effect of the ETL on device performance in planar perovskite solar cells is investigated in detail, and the band bending in different situations is discussed. The ET barrier is shown to be responsible for the poor fill factor (FF) of J-V curves. Introduction of a thin bathocuproine interlayer increases the interface inversion and results in an increase of FF from 56 to 76 %. Some experimental and theoretical results verify these conclusions. Furthermore, this study can provide an interface-engineering strategy to improve device performance.

  6. Follicular fluid oocyte/cumulus-free DNA concentrations as a potential biomolecular marker of embryo quality and IVF outcome.

    Science.gov (United States)

    Dimopoulou, M; Anifandis, G; Messini, C I; Dafopoulos, K; Kouris, S; Sotiriou, S; Satra, M; Vamvakopoulos, N; Messinis, I E

    2014-01-01

    The present prospective study examined the follicular fluid oocyte/cumulus-free DNA concentrations (ff o/c-free DNA) during ovarian stimulation and the possible association between ff o/c-free DNA and embryological results such as embryo quality and pregnancy rate. Eighty-three women undergoing IV/ICSI-ET treatments were prospectively included in this study. ff o/c-free DNA was determined by conventional quantitative real time PCR-Sybr green detection approach. The 83 ff samples were categorized in two groups: group 1 (n = 62) with cumulus oocytes complexes (CoCs) ≥2 and group 2 (n = 21) with CoCs = 1. Group 1 revealed significant higher embryo quality in terms of mean score of embryo transfer (MSET), but lower ff o/c-free DNA concentrations compared to group 2. The two groups showed comparable pregnancy rates (positive hCG and clinical pregnancy). The higher the ff o/c-free DNA concentration, the lower the number of produced oocytes. ff o/c-free DNA did not seem to have any direct role in the IVF outcome. Further research is required to clarify whether ff o/c-free DNA is a biomolecular marker of embryo quality and IVF outcome.

  7. Microphysical, Macrophysical and Radiative Signatures of Volcanic Aerosols in Trade Wind Cumulus Observed by the A-Train

    Science.gov (United States)

    Yuan, T.; Remer, L. A.; Yu, H.

    2011-01-01

    Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-tem1 degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount. is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  8. Microphysical, macrophysical and radiative signatures of volcanic aerosols in trade wind cumulus observed by the A-Train

    Directory of Open Access Journals (Sweden)

    T. Yuan

    2011-07-01

    Full Text Available Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-term degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount, is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  9. Microphysical, macrophysical and radiative signatures of volcanic aerosols in trade wind cumulus observed by the A-Train

    Directory of Open Access Journals (Sweden)

    T. Yuan

    2011-02-01

    Full Text Available Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-term degassing of a low-lying volcano and use of A-Train satellite observations, we show aerosols are associated strongly with modification of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount. We also demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcing", resulting from direct and indirect forcings including both cloud albedo and cloud amount, is almost an order of magnitude higher than aerosol direct forcing alone. The precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  10. Okadaic acid inhibits cell growth and photosynthetic electron transport in the alga Dunaliella tertiolecta

    Energy Technology Data Exchange (ETDEWEB)

    Perreault, Francois; Matias, Marcelo Seleme; Oukarroum, Abdallah [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada); Matias, William Gerson [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada); Laboratorio de Toxicologia Ambiental, LABTOX, Depto. de Engenharia Sanitaria e Ambiental, Universidade Federal de Santa Catarina, Campus Universitario, CEP: 88040-970, Florianopolis, SC (Brazil); Popovic, Radovan, E-mail: popovic.radovan@uqam.ca [Department of Chemistry, Universite du Quebec a Montreal, 2101, Rue Jeanne Mance, Montreal, QC, Canada H2X 2J6 (Canada)

    2012-01-01

    Okadaic acid (OA), which is produced by several dinoflagellate species, is a phycotoxin known to induce a decrease of biomass production in phytoplankton. However, the mechanisms of OA cytotoxicity are still unknown in microalgae. In this study, we exposed the green microalga Dunaliella tertiolecta to OA concentrations of 0.05 to 0.5 {mu}M in order to evaluate its effects on cell division, reactive oxygen species production and photosynthetic electron transport. After 72 h of treatment under continuous illumination, OA concentrations higher than 0.10 {mu}M decreased culture cell density, induced oxidative stress and inhibited photosystem II electron transport capacity. OA effect in D. tertiolecta was strongly light dependent since no oxidative stress was observed when D. tertiolecta was exposed to OA in the dark. In the absence of light, the effect of OA on culture cell density and photosystem II activity was also significantly reduced. Therefore, light appears to have a significant role in the toxicity of OA in microalgae. Our results indicate that the site of OA interaction on photosynthetic electron transport is likely to be at the level of the plastoquinone pool, which can lead to photo-oxidative stress when light absorbed by the light-harvesting complex of photosystem II cannot be dissipated via photochemical pathways. These findings allowed for a better understanding of the mechanisms of OA toxicity in microalgae. - Highlights: Black-Right-Pointing-Pointer Exposition of Dunaliella tertiolecta to okadaic acid in light conditions results in reactive oxygen species formation. Black-Right-Pointing-Pointer Inhibition of photosystem II is dependent on oxidative stress and effects of okadaic acid on the plastoquinone pool. Black-Right-Pointing-Pointer Oxidative stress and inhibition of photosynthesis increase okadaic acid effect on cell density in light conditions. Black-Right-Pointing-Pointer Okadaic acid induces toxicity in algae via both light-dependent and light

  11. Stability and Electronic Structures of CuxS Solar Cell Absorbers: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wei, S. H.; Xu, Q.; Huang, B.; Zhao, Y.; Yan, Y.; Noufi, R.

    2012-07-01

    Cu{sub x}S is one of the most promising solar cell absorber materials that has the potential to replace the leading thin-film solar cell material Cu(In,Ga)Se{sub 2} for high efficiency and low cost. In the past, solar cells based on Cu{sub x}S have reached efficiency as high as 10%, but it also suffers serious stability issues. To further improve its efficiency and especially the stability, it is important to understand the stability and electronic structure of Cu{sub x}S. However, due to the complexity of their crystal structures, no systematic theoretical studies have been carried out to understand the stability and electronic structure of the Cu{sub x}S systems. In this work, using first-principles method, we have systematically studied the crystal and electronic band structures of Cu{sub x}S (1.25 < x {le} 2). For Cu{sub 2}S, we find that all the three chalcocite phases, i.e., the low-chalcocite, the high-chalcocite, and the cubic-chalcocite phases, have direct bandgaps around 1.3-1.5 eV, with the low-chalcocite being the most stable one. However, Cu vacancies can form spontaneously in these compounds, causing instability of Cu{sub 2}S. We find that under Cu-rich condition, the anilite Cu{sub 1.75}S is the most stable structure. It has a predicted bandgap of 1.4 eV and could be a promising solar cell absorber.

  12. Electron Transfer in D-B-A Model Systems and Dye-Sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Wiberg, Joanna

    2010-01-15

    This Thesis presents a thorough study of the electron transfer (ET) processes, both inter-molecular - between dyes for dye-sensitized solar cells (DSSCs), and intra-molecular - in porphyrin based electron donor-bridge-electron acceptor model systems. The focus has been on charge separation and subsequent re-combination in the femtosecond-nanosecond range in both systems. Studying these processes on nanocrystalline mesoporous films in rather heterogeneous systems for solar cell application is quite a challenge. Therefore, the knowledge gained by studying the same type of processes in designed model systems is in-valuable. To this end, ET has been verified and studied in a series of donor-bridge-acceptor (D-B-A) model systems using femtosecond transient absorption. The D-B-A series show photo-induced ET with exponential distance dependence via superexchange interactions. The attenuation factor of the ET rate, beta, was shown to be direction specific, which is in accordance with the McConnell model. A parallel study of the influence of the barrier height showed that the decrease in electronic coupling for the charge recombination (CR) reaction could be correlated to the impact of charge location. The importance of charge location was also used to explain the large differences in energy conversion efficiency found for two solar cell dyes with differently conjugated anchoring groups adsorbed on TiO{sub 2}. The disparity in energy conversion efficiency for these two dyes was ascribed to the effect of differences in electron density on the binding oxygens, rather than efficiency variations in the injection process. An exponential distance dependence for CR was found also for dyes adsorbed on TiO{sub 2}, with attenuation factors similar to those found for the D-B-A system. In addition, the hole transfer to and from NiO films was studied for two p-type dyes that had shown great differences in current generation. The CR was found to be slower for the dye with the strongest

  13. Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research.

    Science.gov (United States)

    Hodnik, Nejc; Dehm, Gerhard; Mayrhofer, Karl J J

    2016-09-20

    The foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like electrolyzers or fuel cells. Transmission electron microscopy (TEM) and scanning transmission electron microscope (STEM) are to a great extent nondestructive characterization tools that provide structural, morphological, and compositional information with nanoscale or even atomic resolution. Due to recent marked advancement in electron microscopy equipment such as aberration corrections and monochromators, such insightful information is now accessible in many institutions around the world and provides huge benefit to everyone using electron microscopy characterization in general. Classical ex situ TEM characterization of random catalyst locations however suffers from two limitations regarding catalysis. First, the necessary low operation pressures in the range of 10(-6) to 10(-9) mbar for TEM are not in line with typical reaction conditions, especially considering electrocatalytic solid-liquid interfaces, so that the active state cannot be assessed. Second, and somewhat related, is the lack of time resolution for the

  14. Particle-in-cell Simulation of Electron Acceleration in Solar Coronal Jets

    Science.gov (United States)

    Baumann, G.; Nordlund, Å.

    2012-11-01

    We investigate electron acceleration resulting from three-dimensional magnetic reconnection between an emerging, twisted magnetic flux rope and a pre-existing weak, open magnetic field. We first follow the rise of an unstable, twisted flux tube with a resistive MHD simulation where the numerical resolution is enhanced by using fixed mesh refinement. As in previous MHD investigations of similar situations, the rise of the flux tube into the pre-existing inclined coronal magnetic field results in the formation of a solar coronal jet. A snapshot of the MHD model is then used as an initial and boundary condition for a particle-in-cell simulation, using up to half a billion cells and over 20 billion charged particles. Particle acceleration occurs mainly in the reconnection current sheet, with accelerated electrons displaying a power law in the energy probability distribution with an index of around -1.5. The main acceleration mechanism is a systematic electric field, striving to maintaining the electric current in the current sheet against losses caused by electrons not being able to stay in the current sheet for more than a few seconds at a time.

  15. A genetically encoded tag for correlated light and electron microscopy of intact cells, tissues, and organisms.

    Directory of Open Access Journals (Sweden)

    Xiaokun Shu

    2011-04-01

    Full Text Available Electron microscopy (EM achieves the highest spatial resolution in protein localization, but specific protein EM labeling has lacked generally applicable genetically encoded tags for in situ visualization in cells and tissues. Here we introduce "miniSOG" (for mini Singlet Oxygen Generator, a fluorescent flavoprotein engineered from Arabidopsis phototropin 2. MiniSOG contains 106 amino acids, less than half the size of Green Fluorescent Protein. Illumination of miniSOG generates sufficient singlet oxygen to locally catalyze the polymerization of diaminobenzidine into an osmiophilic reaction product resolvable by EM. MiniSOG fusions to many well-characterized proteins localize correctly in mammalian cells, intact nematodes, and rodents, enabling correlated fluorescence and EM from large volumes of tissue after strong aldehyde fixation, without the need for exogenous ligands, probes, or destructive permeabilizing detergents. MiniSOG permits high quality ultrastructural preservation and 3-dimensional protein localization via electron tomography or serial section block face scanning electron microscopy. EM shows that miniSOG-tagged SynCAM1 is presynaptic in cultured cortical neurons, whereas miniSOG-tagged SynCAM2 is postsynaptic in culture and in intact mice. Thus SynCAM1 and SynCAM2 could be heterophilic partners. MiniSOG may do for EM what Green Fluorescent Protein did for fluorescence microscopy.

  16. Direct monitoring of ultrafast electron and hole dynamics in perovskite solar cells.

    Science.gov (United States)

    Piatkowski, Piotr; Cohen, Boiko; Javier Ramos, Francisco; Di Nunzio, Maria; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Ahmad, Shahzada; Douhal, Abderrazzak

    2015-06-14

    Organic-inorganic hybrid perovskite solar cells have emerged as cost effective efficient light-to-electricity conversion devices. Unravelling the time scale and the mechanisms that govern the charge carrier dynamics is of paramount importance for a clear understanding and further optimization of the perovskite based devices. For the classical FTO/bulk titania blocking layer/mesoporous titania/perovskite/Spiro-OMeTAD (FTO/TPS) cell, further detailed and systematic studies of the ultrafast events related to exciton generation, electron and hole transfer, ultrafast relaxation are still needed. We characterize the initial ultrafast processes attributed to the exciton-perovskite lattice interactions influenced by charge transfer to the electron and hole transporters that precede the exciton diffusion into free charge carriers occurring in the sensitizer. Time-resolved transient absorption studies of the FTO/perovskite and FTO/TPS samples under excitation at different wavelengths and at low fluence 2 (μJ cm(-2)) indicate the sub-picosecond electron and hole injection into titania and Spiro-OMeTAD, respectively. Furthermore, the power-dependent femtosecond transient absorption measurements support the ultrafast charge transfer and show strong Auger-type multiparticle interactions at early times. We reveal that the decays of the internal trap states are the same for both films, while those at surfaces differ. The contribution of the former in the recombination is small, thus increasing the survival probability of the charges in the excited perovskite.

  17. Kalkitoxin Inhibits Angiogenesis, Disrupts Cellular Hypoxic Signaling, and Blocks Mitochondrial Electron Transport in Tumor Cells

    Directory of Open Access Journals (Sweden)

    J. Brian Morgan

    2015-03-01

    Full Text Available The biologically active lipopeptide kalkitoxin was previously isolated from the marine cyanobacterium Moorea producens (Lyngbya majuscula. Kalkitoxin exhibited N-methyl-d-aspartate (NMDA-mediated neurotoxicity and acted as an inhibitory ligand for voltage-sensitive sodium channels in cultured rat cerebellar granule neurons. Subsequent studies revealed that kalkitoxin generated a delayed form of colon tumor cell cytotoxicity in 7-day clonogenic cell survival assays. Cell line- and exposure time-dependent cytostatic/cytotoxic effects were previously observed with mitochondria-targeted inhibitors of hypoxia-inducible factor-1 (HIF-1. The transcription factor HIF-1 functions as a key regulator of oxygen homeostasis. Therefore, we investigated the ability of kalkitoxin to inhibit hypoxic signaling in human tumor cell lines. Kalkitoxin potently and selectively inhibited hypoxia-induced activation of HIF-1 in T47D breast tumor cells (IC50 5.6 nM. Mechanistic studies revealed that kalkitoxin inhibits HIF-1 activation by suppressing mitochondrial oxygen consumption at electron transport chain (ETC complex I (NADH-ubiquinone oxidoreductase. Further studies indicate that kalkitoxin targets tumor angiogenesis by blocking the induction of angiogenic factors (i.e., VEGF in tumor cells.

  18. Efficiency Enhancement of Inverted Structure Perovskite Solar Cells via Oleamide Doping of PCBM Electron Transport Layer.

    Science.gov (United States)

    Xia, Fei; Wu, Qiliang; Zhou, Pengcheng; Li, Yi; Chen, Xiang; Liu, Qing; Zhu, Jun; Dai, Songyuan; Lu, Yalin; Yang, Shangfeng

    2015-06-24

    An amphiphilic surfactant, oleamide, was applied to dope the PCBM electron transport layer (ETL) of inverted structure perovskite solar cells (ISPSCs), resulting in a dramatic efficiency enhancement. Under the optimized oleamide doping ratio of 5.0 wt %, the power conversion efficiency of the CH3NH3PbIxCl(3-x) perovskite-based ISPSC device is enhanced from 10.05% to 12.69%, and this is primarily due to the increases of both fill factor and short-circuit current. According to the surface morphology study of the perovskite/PCBM bilayer film, oleamide doping improves the coverage of PCBM ETL onto the perovskite layer, and this is beneficial for the interfacial contact between the perovskite layer and the Ag cathode and consequently the electron transport from perovskite to the Ag cathode. Such an improved electron transport induced by oleamide doping is further evidenced by the impedance spectroscopic study, revealing the prohibited electron-hole recombination at the interface between the perovskite layer and the Ag cathode.

  19. Design of aromatic-containing cell-penetrating peptide mimics with structurally modified π electronics.

    Science.gov (United States)

    deRonde, Brittany M; Birke, Alexander; Tew, Gregory N

    2015-02-09

    Cell-penetrating peptides (CPPs) and their synthetic mimics (CPPMs) represent a class of molecules that facilitate the intracellular delivery of various cargo. Previous studies indicated that the presence of aromatic functionalities improved CPPM activity. Given that aromatic functionalities play prominent roles in membrane biology and participate in various π interactions, we explored whether these interactions could be optimized for improved CPPM activity. CPPMs were synthesized by ring-opening metathesis polymerization by using monomers that contained aromatic rings substituted with electron-donating and electron-withdrawing groups and covered an electrostatic potential range from -29.69 to +15.57 kcal mol(-1) . These groups altered the quadrupole moments of the aromatic systems and were used to test if such structural modifications changed CPPM activity. CPPMs were added to dye-loaded vesicles and the release of carboxyfluorescein was monitored as a function of polymer concentration. Changes in the effective polymer concentration to release 50% of the dye (effective concentration, EC50 ) were monitored. Results from this assay showed that the strength of the electron-donating and electron-withdrawing groups incorporated in the CPPMs did not alter polymer EC50 values or activity. This suggests that other design parameters may have a stronger impact on CPPM activity. In addition, these results indicate that a wide range of aromatic groups can be incorporated without negatively impacting polymer activity.

  20. Geminate electron-hole recombination in organic photovoltaic cells. A semi-empirical theory

    Science.gov (United States)

    Wojcik, Mariusz; Nowak, Artur; Seki, Kazuhiko

    2017-02-01

    We propose a semi-empirical theory which describes the geminate electron-hole separation probability in both homogeneous systems and donor-acceptor heterojunction systems applicable in organic photovoltaics. The theory is based on the results of extensive simulation calculations, which were carried out using various lattice models of the medium and different charge-carrier hopping mechanisms, over the parameter ranges typical for organic solar cells. It is found that the electron-hole separation probability can be conveniently described in terms of measurable parameters by a formula whose functional form is derived from the existing recombination theories, and which contains only one empirical parameter. For homogeneous systems, this parameter is determined by the structure of the medium and only weakly depends on the charge-carrier hopping mechanism. In the case of donor-acceptor heterojunction systems, this empirical parameter shows a simple power-law dependence on the product of the dielectric constant and inter-molecular contact distance. We also study the effect of heterojunction structure on the electron-hole separation probability and show that this probability decreases with increasing roughness of the heterojunction. By analyzing the simulation results obtained for systems under the influence of an external electric field, we find that the field effect on the electron-hole separation probability in donor-acceptor heterojunction systems is weaker than in homogeneous systems. We also describe this field effect by a convenient empirical formula.

  1. Geminate electron-hole recombination in organic photovoltaic cells. A semi-empirical theory.

    Science.gov (United States)

    Wojcik, Mariusz; Nowak, Artur; Seki, Kazuhiko

    2017-02-07

    We propose a semi-empirical theory which describes the geminate electron-hole separation probability in both homogeneous systems and donor-acceptor heterojunction systems applicable in organic photovoltaics. The theory is based on the results of extensive simulation calculations, which were carried out using various lattice models of the medium and different charge-carrier hopping mechanisms, over the parameter ranges typical for organic solar cells. It is found that the electron-hole separation probability can be conveniently described in terms of measurable parameters by a formula whose functional form is derived from the existing recombination theories, and which contains only one empirical parameter. For homogeneous systems, this parameter is determined by the structure of the medium and only weakly depends on the charge-carrier hopping mechanism. In the case of donor-acceptor heterojunction systems, this empirical parameter shows a simple power-law dependence on the product of the dielectric constant and inter-molecular contact distance. We also study the effect of heterojunction structure on the electron-hole separation probability and show that this probability decreases with increasing roughness of the heterojunction. By analyzing the simulation results obtained for systems under the influence of an external electric field, we find that the field effect on the electron-hole separation probability in donor-acceptor heterojunction systems is weaker than in homogeneous systems. We also describe this field effect by a convenient empirical formula.

  2. Comparison of oxygen and hypochlorite as cathodic electron acceptor in microbial fuel cells.

    Science.gov (United States)

    Jadhav, D A; Ghadge, A N; Mondal, Debika; Ghangrekar, M M

    2014-02-01

    Effect of oxygen and sodium hypochlorite (NaOCl) as cathodic electron acceptors on performance of a clayware microbial fuel cell (MFC) was evaluated in this study. Maximum power density of 6.57 W/m(3) was obtained with NaOCl as catholyte, which is about 9 times higher than oxygen being used as an electron acceptor. Voltammetry and Tafel analysis further supported the faster reduction kinetics lead to increase in power output and reduction in internal resistance of MFC operated with NaOCl as an electron acceptor. Using NaOCl as catholyte, higher exchange current density of 10.91 and 11.52 mA/m(2) and lower charge transfer resistance of 0.58 and 0.56 kΩ m(2) was observed for anode and cathode, respectively. Higher organic matter removal of about 90% with 25% Coulombic efficiency was achieved using NaOCl as catholyte. Higher internal resistance, lower cathode potential and slow reduction kinetics deteriorated performance of MFC using oxygen as cathodic electron acceptor.

  3. Efficient inverted polymer solar cells integrated with a compound electron extraction layer

    Science.gov (United States)

    Ma, Zhong-Sheng; Wang, Qian-Kun; Li, Chi; Li, Yan-Qing; Zhang, Dan-Dan; Liu, Weimin; Wang, Pengfei; Tang, Jian-Xin

    2015-12-01

    We constructed an effective electron extraction layer (EEL) used for polymer solar cells by integrating one new kind of organic material of 4,4‧-(1,4-phenylene) bis(2-phenyl-6-p-tolylnicotinonitrile) (p-PPtNT) and cesium carbonate (Cs2CO3) used as a compound EEL (CEEL). The CEEL based device exhibits an ideal PCE of 4.15%, corresponding to an enhancement 220% in contrast to that of control device without EEL, which is also comparable to that of ZnO based device. Our analyses indicated that the remarkably improved PCE for CEEL based device is mainly ascribed to the Ohmic contact and the negligible electron extraction barrier at cathode/active layer by inserting CEEL.

  4. Electron and Hole Drift Mobility Measurements on Methylammonium Lead Iodide Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Maynard, Brian; Long, Qi; Schiff, Eric A.; Yang, Mengjin; Zhu, Kai; Kottokkaran, Ranjith; Abbas, Hisham; Dalal, Vikram L.

    2016-04-25

    We report nanosecond domain time-of-flight measurements of electron and hole photocarriers in methylammonium lead iodide perovskite solar cells. The mobilities ranged from 0.06 to 1.4 cm2/Vs at room temperature, but there is little systematic difference between the two carriers. We also find that the drift mobilities are dispersive (time-dependent). The dispersion parameters are in the range of 0.4-0.7, and they imply that terahertz domain mobilities will be much larger than nanosecond domain mobilities. The temperature-dependences of the dispersion parameters are consistent with confinement of electron and hole transport to fractal-like spatial networks within nanoseconds of their photogeneration.

  5. Electron temperature anisotropy in an expanding plasma: Particle-in-Cell simulations

    CERN Document Server

    Camporeale, Enrico; 10.1088/0004-637X/710/2/1848

    2010-01-01

    We perform fully-kinetic particle-in-cell simulations of an hot plasma that expands radially in a cylindrical geometry. The aim of the paper is to study the consequent development of the electron temperature anisotropy in an expanding plasma flow as found in a collisionless stellar wind. Kinetic plasma theory and simulations have shown that the electron temperature anisotropy is controlled by fluctuations driven by electromagnetic kinetic instabilities. In this study the temperature anisotropy is driven self-consistently by the expansion. While the expansion favors an increase of parallel anisotropy ($T_\\parallel>T_\\perp$), the onset of the firehose instability will tend to decrease it. We show the results for a supersonic, subsonic, and static expansion flows, and suggest possible applications of the results for the solar wind and other stellar winds.

  6. Heptachlor induced mitochondria-mediated cell death via impairing electron transport chain complex III

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seokheon; Kim, Joo Yeon; Hwang, Joohyun [Department of Molecular Biology, Sejong University, Seoul 143-747 (Korea, Republic of); Shin, Ki Soon [Department of Biology, Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kang, Shin Jung, E-mail: sjkang@sejong.ac.kr [Department of Molecular Biology, Sejong University, Seoul 143-747 (Korea, Republic of)

    2013-08-09

    Highlights: •Heptachlor inhibited mitochondrial electron transport chain complex III activity. •Heptachlor promoted generation of reactive oxygen species. •Heptachlor induced Bax activation. •Heptachlor induced mitochondria-mediated and caspase-dependent apoptosis. -- Abstract: Environmental toxins like pesticides have been implicated in the pathogenesis of Parkinson’s disease (PD). Epidemiological studies suggested that exposures to organochlorine pesticides have an association with an increased PD risk. In the present study, we examined the mechanism of toxicity induced by an organochlorine pesticide heptachlor. In a human dopaminergic neuroblastoma SH-SY5Y cells, heptachlor induced both morphological and functional damages in mitochondria. Interestingly, the compound inhibited mitochondrial electron transport chain complex III activity. Rapid generation of reactive oxygen species and the activation of Bax were then detected. Subsequently, mitochondria-mediated, caspase-dependent apoptosis followed. Our results raise a possibility that an organochlorine pesticide heptachlor can act as a neurotoxicant associated with PD.

  7. Efficient Regular Perovskite Solar Cells Based on Pristine [70]Fullerene as Electron-Selective Contact.

    Science.gov (United States)

    Collavini, Silvia; Kosta, Ivet; Völker, Sebastian F; Cabanero, German; Grande, Hans J; Tena-Zaera, Ramón; Delgado, Juan Luis

    2016-06-08

    [70]Fullerene is presented as an efficient alternative electron-selective contact (ESC) for regular-architecture perovskite solar cells (PSCs). A smart and simple, well-described solution processing protocol for the preparation of [70]- and [60]fullerene-based solar cells, namely the fullerene saturation approach (FSA), allowed us to obtain similar power conversion efficiencies for both fullerene materials (i.e., 10.4 and 11.4 % for [70]- and [60]fullerene-based devices, respectively). Importantly, despite the low electron mobility and significant visible-light absorption of [70]fullerene, the presented protocol allows the employment of [70]fullerene as an efficient ESC. The [70]fullerene film thickness and its solubility in the perovskite processing solutions are crucial parameters, which can be controlled by the use of this simple solution processing protocol. The damage to the [70]fullerene film through dissolution during the perovskite deposition is avoided through the saturation of the perovskite processing solution with [70]fullerene. Additionally, this fullerene-saturation strategy improves the performance of the perovskite film significantly and enhances the power conversion efficiency of solar cells based on different ESCs (i.e., [60]fullerene, [70]fullerene, and TiO2 ). Therefore, this universal solution processing protocol widens the opportunities for the further development of PSCs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Fulleropyrrolidinium Iodide As an Efficient Electron Transport Layer for Air-Stable Planar Perovskite Solar Cells.

    Science.gov (United States)

    Huang, Jiabin; Yu, Xuegong; Xie, Jiangsheng; Li, Chang-Zhi; Zhang, Yunhai; Xu, Dikai; Tang, Zeguo; Cui, Can; Yang, Deren

    2016-12-21

    Organic-inorganic halide perovskite solar cells have attracted great attention in recent years. But there are still a lot of unresolved issues related to the perovskite solar cells such as the phenomenon of anomalous hysteresis characteristics and long-term stability of the devices. Here, we developed a simple three-layered efficient perovskite device by replacing the commonly employed PCBM electrical transport layer with an ultrathin fulleropyrrolidinium iodide (C60-bis) in an inverted p-i-n architecture. The devices with an ultrathin C60-bis electronic transport layer yield an average power conversion efficiency of 13.5% and a maximum efficiency of 15.15%. Steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements show that the high performance is attributed to the efficient blocking of holes and high extraction efficiency of electrons by C60-bis, due to a favorable energy level alignment between the CH3NH3PbI3 and the Ag electrodes. The hysteresis effect and stability of our perovskite solar cells with C60-bis become better under indoor humidity conditions.

  9. Comparison between electron-beam and furnace rapid isothermal anneals of phosphorus-implanted solar cells

    Science.gov (United States)

    Lulli, G.; Merli, P. G.; Negrini, P.; Ostoja, P.; Solmi, S.

    1983-07-01

    Solar cells have been fabricated using single crystal silicon wafers, implanted at 10-keV energy with 10 to the 15th P(+)/sq cm. Rapid isothermal heat treatments at temperatures ranging between 500 and 1000 C were used to anneal the implanted damage. Two different methods have been used: electron-beam and furnace annealing for times ranging between 0.5 and 5 min, and between 2 and 5 min, respectively. Characterization of P(+)-implanted layers and of completed solar cells allowed us to demonstrate that rapid isothermal anneals with furnace and electron beam give equivalent results. The efficiency of solar cells which are annealed using these rapid isothermal processes is fairly good (13.5 percent), even if slightly lower than that obtained with conventional aneals (750 C for 30 min). The reduced efficiency is a consequence of the lower value of the open circuit voltage. It is demonstrated that this effect is caused by residual defects in the space-charge region, produced by ion implantation.

  10. Co-cultivation of conjunctival epithelial cells and Chlamydia trachomatis: electron microscopic findings.

    Science.gov (United States)

    Kim, D S; Ko, M K; Kang, K T

    1998-06-01

    This study used primary culture of rabbit conjunctival epithelial cells to investigate the infection process of chlamydia. The epithelial cells isolated from conjunctiva of rabbit were initially cultured for three weeks. After attaining confluence they were infected with Chlamydia trachomatis (C. trachomatis) serotype D, and after co-cultivation for 24, 48, and 96 hours, electron microscopic study was performed. An inclusion body, a characteristic finding of chlamydial infection, was observed in the vicinity of the nucleus after 24 hours of co-cultivation. It contained a large number of elementary and reticulate bodies and their intermediate forms. Infectious particles known as elementary bodies were noted in the inclusion as 20 to 30 microns sized round bodies with an electron dense core. Reticulate bodies were also noted; they too were round but somewhat pleomorphic and larger than elementary bodies. Some reticulate bodies multiplied actively by means of binary fission. In this study, we observed the characteristic changes of C. trachomatis-infected cells; this in-vitro system might provide a suitable model for the study of some aspects of the pathogenesis of ocular chlamydia infection.

  11. A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

    Science.gov (United States)

    Hao, Yan; Yang, Wenxing; Zhang, Lei; Jiang, Roger; Mijangos, Edgar; Saygili, Yasemin; Hammarström, Leif; Hagfeldt, Anders; Boschloo, Gerrit

    2016-12-01

    Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy--by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte--to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system.

  12. Fatty acid composition of porcine cumulus oocyte complexes (COC) during maturation: effect of the lipid modulators trans-10, cis-12 conjugated linoleic acid (t10,c12 CLA) and forskolin.

    Science.gov (United States)

    Prates, E G; Alves, S P; Marques, C C; Baptista, M C; Horta, A E M; Bessa, R J B; Pereira, R M

    2013-05-01

    The effect of maturation and of two lipid modulators supplementation along in vitro maturation (IVM) on fatty acid (FA) and dimethylacetal (DMA) composition of porcine cumulus oocyte complexes (COC) were studied. Abattoir-derived immature COC were analyzed for FA and DMA or submitted to IVM as follows: control group; t10,c12 CLA group, t10,c12 CLA supplementation for 44 h; Forskolin group, forskolin supplementation during the initial 2 h; t10,c12 CLA + forskolin group, t10,c12 CLA for 44 h and forskolin for just 2h. Each experimental group had five replicates. FA analysis of oocytes, cumulus cells (CC), follicular fluid, and culture media were performed by gas-liquid chromatography. Oocytes and their CC had different FA composition. Oocytes were richer in saturated FA (SFA) preferentially maintaining their FA profile during maturation. Mature CC had the highest polyunsaturated FA (PUFA) content. Five individual and total SFA, and monounsaturated FA (MUFA), notably oleic acid (c9-18:1), percentages were lower (P ≤ 0.023) in mature than in immature CC. t10,c12 CLA was accumulated by COC from t10,c12 CLA and t10,c12 CLA + forskolin groups, mostly in CC where MUFA and an eicosatrienoic isomer decreased (P ≤ 0.043). Nevertheless, PUFA or FA and DMA total content were not affected. Arachidonic acid was reduced in t10,c12 CLA + forskolin CC and hexadecanal-DMA-16:0 in t10,c12 CLA CC. Forskolin alone increased (P ≤ 0.043) c9-18:1 in oocytes. In conclusion, maturation process clearly changed porcine COC FA and DMA profiles, mostly of CC, also more susceptible to modifications induced by t10,c12 CLA. This possibility of manipulating COC lipid composition during IVM could be used to improve oocyte quality/cryopreservation efficiency.

  13. An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery

    Directory of Open Access Journals (Sweden)

    Reddad El-Moznine

    2007-10-01

    Full Text Available In this paper we present an inexpensive electronic measurement instrumentationdeveloped in our laboratory, to measure and plot the impedance of a loaded fuel cell orbattery. Impedance measurements were taken by using the load modulation method. Thisinstrumentation has been developed around a VXI system stand which controls electroniccards. Software under Hpvee® was developed for automatic measurements and the layout ofthe impedance of the fuel cell on load. The measurement environment, like the ambienttemperature, the fuel cell temperature, the level of the hydrogen, etc..., were taken withseveral sensors that enable us to control the measurement. To filter the noise and theinfluence of the 50Hz, we have implemented a synchronous detection which filters in a verynarrow way around the useful signal. The theoretical result obtained by a simulation underPspice® of the method used consolidates the choice of this method and the possibility ofobtaining correct and exploitable results. The experimental results are preliminary results ona 12V vehicle battery, having an inrush current of 330A and a capacity of 40Ah (impedancemeasurements on a fuel cell are in progress, and will be the subject of a forthcoming paper.The results were plotted at various nominal voltages of the battery (12.7V, 10V, 8V and 5Vand with two imposed currents (0.6A and 4A. The Nyquist diagram resulting from theexperimental data enable us to show an influence of the load of the battery on its internalimpedance. The similitude in the graph form and in order of magnitude of the valuesobtained (both theoretical and practical enables us to validate our electronic measurementinstrumentation. One of the future uses for this instrumentation is to integrate it with several control sensors, on a vehicle as an embedded system to monitor the degradation of fuel cell membranes.

  14. Probing Electron Transfer Mechanisms in Shewanella oneidensis MR-1 using a Nanoelectrode Platform and Single-Cell Imaging

    Science.gov (United States)

    2010-01-01

    nanowires The capability of bacteria, such as Shewanella and Geobacter ,to transfer electrons from metabolism of organic sources to electrodes without...filamentous pili growth from Shewanella and Geobacter cells report a third mechanism for extracellular electron transfer through biological nanowires (12

  15. New conjugated molecular scaffolds based on [2,2]paracyclophane as electron acceptors for organic photovoltaic cells.

    Science.gov (United States)

    Yang, Yang; Zhang, Guanxin; Yu, Chenmin; He, Chang; Wang, Jianguo; Chen, Xin; Yao, Jingjing; Liu, Zitong; Zhang, Deqing

    2014-09-07

    Two conjugated molecules with a [2,2]paracyclophane core were designed as non-fullerene electron acceptors for photovoltaic cells. Using as the donor, a high power conversion efficiency (2.69%) is achieved for the blending thin film of with , which is relatively high for solution-processed OPVs based on small molecular non-fullerene acceptors and as the electron donor.

  16. Universal Features of Electron Dynamics in Solar Cells with TiO2 Contact: From Dye Solar Cells to Perovskite Solar Cells.

    Science.gov (United States)

    Todinova, Anna; Idígoras, Jesús; Salado, Manuel; Kazim, Samrana; Anta, Juan A

    2015-10-01

    The electron dynamics of solar cells with mesoporous TiO2 contact is studied by electrochemical small-perturbation techniques. The study involved dye solar cells (DSC), solid-state perovskite solar cells (SSPSC), and devices where the perovskite acts as sensitizer in a liquid-junction device. Using a transport-recombination continuity equation we found that mid-frequency time constants are proper lifetimes that determine the current-voltage curve. This is not the case for the SSPSC, where a lifetime of ∼1 μs, 1 order of magnitude longer, is required to reproduce the current-voltage curve. This mismatch is attributed to the dielectric response on the mid-frequency component. Correcting for this effect, lifetimes lie on a common exponential trend with respect to open-circuit voltage. Electron transport times share a common trend line too. This universal behavior of lifetimes and transport times suggests that the main difference between the cells is the power to populate the mesoporous TiO2 contact with electrons.

  17. Evolution of electron transfer out of the cell: comparative genomics of six Geobacter genomes

    Directory of Open Access Journals (Sweden)

    Young Nelson D

    2010-01-01

    Full Text Available Abstract Background Geobacter species grow by transferring electrons out of the cell - either to Fe(III-oxides or to man-made substances like energy-harvesting electrodes. Study of Geobacter sulfurreducens has shown that TCA cycle enzymes, inner-membrane respiratory enzymes, and periplasmic and outer-membrane cytochromes are required. Here we present comparative analysis of six Geobacter genomes, including species from the clade that predominates in the subsurface. Conservation of proteins across the genomes was determined to better understand the evolution of Geobacter species and to create a metabolic model applicable to subsurface environments. Results The results showed that enzymes for acetate transport and oxidation, and for proton transport across the inner membrane were well conserved. An NADH dehydrogenase, the ATP synthase, and several TCA cycle enzymes were among the best conserved in the genomes. However, most of the cytochromes required for Fe(III-reduction were not, including many of the outer-membrane cytochromes. While conservation of cytochromes was poor, an abundance and diversity of cytochromes were found in every genome, with duplications apparent in several species. Conclusions These results indicate there is a common pathway for acetate oxidation and energy generation across the family and in the last common ancestor. They also suggest that while cytochromes are important for extracellular electron transport, the path of electrons across the periplasm and outer membrane is variable. This combination of abundant cytochromes with weak sequence conservation suggests they may not be specific terminal reductases, but rather may be important in their heme-bearing capacity, as sinks for electrons between the inner-membrane electron transport chain and the extracellular acceptor.

  18. Amyloid plaque structure and cell surface interactions of β-amyloid fibrils revealed by electron tomography

    Science.gov (United States)

    Han, Shen; Kollmer, Marius; Markx, Daniel; Claus, Stephanie; Walther, Paul; Fändrich, Marcus

    2017-01-01

    The deposition of amyloid fibrils as plaques is a key feature of several neurodegenerative diseases including in particular Alzheimer’s. This disease is characterized, if not provoked, by amyloid aggregates formed from Aβ peptide that deposit inside the brain or are toxic to neuronal cells. We here used scanning transmission electron microscopy (STEM) to determine the fibril network structure and interactions of Aβ fibrils within a cell culture model of Alzheimer’s disease. STEM images taken from the formed Aβ amyloid deposits revealed three main types of fibril network structures, termed amorphous meshwork, fibril bundle and amyloid star. All three were infiltrated by different types of lipid inclusions from small-sized exosome-like structures (50–100 nm diameter) to large-sized extracellular vesicles (up to 300 nm). The fibrils also presented strong interactions with the surrounding cells such that fibril bundles extended into tubular invaginations of the plasma membrane. Amyloid formation in the cell model was previously found to have an intracellular origin and we show here that it functionally destroys the integrity of the intracellular membranes as it leads to lysosomal leakage. These data provide a mechanistic link to explain why intracellular fibril formation is toxic to the cell. PMID:28240273

  19. The electron affinity difference in CdS/CuInSe{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Al Kuhaimi, Siham A. [Physics Department, Faculty of Education, Siteen St. Malaz, Riyadh-Saudi Arabia, Riyadh (Saudi Arabia)

    1998-03-16

    The electron affinity difference {Delta}E{sub c}={chi}{sub 1}-{chi}{sub 2}, in CdS/CuInSe{sub 2} solar cells fabricated by four different processes has been measured from observations of the variations of open-circuit voltages with temperature. For CdS/CuInSe{sub 2} cells the values of {Delta}E{sub c} lie between 0.20 and 0.30 eV and are found to be independent of the process of cell fabrication. The use of CdZnS in place of CdS reduces the value of {Delta}E{sub c} to slightly less than 0.1 eV. The method used for the measurement of {Delta}E{sub c} is very simple. The values of the saturation current I{sub 0} for the different types of cells have been estimated from the slopes of qV{sub oc} versus kT characteristics and compared with those obtained from ln I versus V curves. The values of I{sub 0} found for each cell by the two methods are in fair agreement

  20. Remarks on the radiation chemistry of radiation damage in cells. [X radiation, electrons

    Energy Technology Data Exchange (ETDEWEB)

    Powers, E.L.

    1975-01-01

    Several models of the actions of compounds that sensitize cells to x-irradiation are reviewed and commented on. The electron sequestration model is described in detail and typical experimental results upon which it is based are reviewed. The varieties of responses induced by a number of sensitizers and their antagonists are stressed; there is no single, simple chemical explanation that can account for all the results. However, the importance of the e/sup -//sub aq/ -- .OH relation is evident in all the experimental results with the compounds tested to date.

  1. Pleomorphic (giant cell) carcinoma of the intestine. An immunohistochemical and electron microscopic study

    DEFF Research Database (Denmark)

    Bak, Martin; Teglbjaerg, P S

    1989-01-01

    reaction for neuron-specific enolase (NSE) was found in three tumors and a positive reaction for chromogranin was found in one tumor. On electron microscopic study, intracytoplasmic whorls of intermediate filaments were seen in the perinuclear area. Dense core "neurosecretory" granules were rarely seen......Pleomorphic (giant cell) carcinomas have been described in the lungs, thyroid, pancreas, and gallbladder. Two pleomorphic carcinomas of the small bowel and two of the large bowel are presented. On light microscopic study, the carcinomas were solid, without squamous or glandular differentiation...

  2. A review and design of power electronics converters for fuel cell hybrid system applications

    DEFF Research Database (Denmark)

    Zhang, Zhe; Pittini, Riccardo; Andersen, Michael A. E.

    2012-01-01

    This paper presents an overview of most promising power electronics topologies for a fuel cell hybrid power conversion system which can be utilized in many applications such as hybrid electrical vehicles (HEV), distributed generations (DG) and uninterruptible-power-supply (UPS) systems. Then......, a multiple-input power conversion system including a decoupled dual-input converter and a three-phase neutral-point-clamped (NPC) inverter is proposed. The system can operate in both stand-alone and grid-connected modes. Simulation and experimental results are provided to show the feasibility of the proposed...

  3. Effects of Electron-Beam Irradiation on Buccal-Cell DNA

    OpenAIRE

    2003-01-01

    Buccal cells were collected from 29 participants, by use of mouthwash rinses, and were split into equal aliquots, with one aliquot irradiated by electron-beam (E-beam) irradiation equivalent to the sterilizing dosage used by the U.S. Postal Service and the other left untreated. Aliquots were extracted and tested for DNA yields (e.g., TaqMan assay for quantifying human genomic DNA), genomic integrity, and amplification-based analysis of genetic variants (e.g., single-nucleotide polymorphisms [...

  4. Improving High-resolution Weather Forecasts using the Weather Research and Forecasting (WRF) Model with Upgraded Kain-Fritsch Cumulus Scheme

    Science.gov (United States)

    High-resolution weather forecasting is affected by many aspects, i.e. model initial conditions, subgrid-scale cumulus convection and cloud microphysics schemes. Recent 12km grid studies using the Weather Research and Forecasting (WRF) model have identified the importance of inco...

  5. RACORO Continental Boundary Layer Cloud Investigations: 3. Separation of Parameterization Biases in Single-Column Model CAM5 Simulations of Shallow Cumulus

    Science.gov (United States)

    Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; Fridlind, Ann; Endo, Satoshi; Song, Hua; Feng, Sha; Toto, Tami; Li, Zhijin; Zhang, Minghua

    2015-01-01

    Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) Project has constructed case studies from the Atmospheric Radiation Measurement Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only a relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.

  6. Relationship between the peripheral concentrations of estradiol-17β (E2) and preovulatory characteristics of cumulus-oocyte complexes (COCs) during superovulation treatment in Japanese Black cows.

    Science.gov (United States)

    Kitahara, Go; Kamimura, Shunichi; Hamana, Katsumi

    2011-02-01

    The relationship between the peripheral concentrations of estradiol-17β (E(2)) and the preovulatory characteristics of cumulus oocyte complexes (COCs) during superovulation treatment was investigated in Japanese Black cows. A superovulation regimen with FSH treatment in a descending manner was commenced on day 7 (n=3) or day 10 (n=2) of the estrous cycle (day 0=estrus). Peripheral blood was collected to measure E(2) concentrations twice a day throughout the treatment. Ovariectomies were performed at 100 h after the initial FSH treatment in five cows. Every follicle more than 8 mm in diameter was isolated from the ovaries, and cumulus-oocyte complexes (COCs) were gently aspirated. The COCs were then separated into three groups based on the characteristics of the cumulus (compact, expanded and denuded) and subgrouped based on the stage of the nucleus in the oocytes (GV, GVBD). Plasma E(2) concentrations tended to increase gradually and reached the peak level at around 84 h (E(2)-84: n=3) or 96 h (E(2)-96: n=2) after the initial FSH treatment. The ratio of COCs with expanded cumulus was significantly higher in E(2)-84 than in E(2)-96 (Psuperovulation treatment in Japanese Black cows.

  7. Altered theca and cumulus oocyte complex gene expression, follicular arrest and reduced fertility in cows with dominant follicle follicular fluid androgen excess.

    Directory of Open Access Journals (Sweden)

    Adam F Summers

    Full Text Available Aspiration of bovine follicles 12-36 hours after induced corpus luteum lysis serendipitously identified two populations of cows, one with High androstenedione (A4; >40 ng/ml; mean = 102 and another with Low A4 (<20 ng/ml; mean = 9 in follicular fluid. We hypothesized that the steroid excess in follicular fluid of dominant follicles in High A4 cows would result in reduced fertility through altered follicle development and oocyte maternal RNA abundance. To test this hypothesis, estrous cycles of cows were synchronized and ovariectomy was performed 36 hours later. HPLC MS/MS analysis of follicular fluid showed increased dehydroepiandrosterone (6-fold, A4 (158-fold and testosterone (31-fold in the dominant follicle of High A4 cows. However, estrone (3-fold and estradiol (2-fold concentrations were only slightly elevated, suggesting a possible inefficiency in androgen to estrogen conversion in High A4 cows. Theca cell mRNA expression of LHCGR, GATA6, CYP11A1, and CYP17A1 was greater in High A4 cows. Furthermore, abundance of ZAR1 was decreased 10-fold in cumulus oocyte complexes from High A4 cows, whereas NLRP5 abundance tended to be 19.8-fold greater (P = 0.07. There was a tendency for reduction in stage 4 follicles in ovarian cortex samples from High A4 cows suggesting that progression to antral stages were impaired. High A4 cows tended (P<0.07 to have a 17% reduction in calving rate compared with Low A4 cows suggesting reduced fertility in the High A4 population. These data suggest that the dominant follicle environment of High A4 cows including reduced estrogen conversion and androgen excess contributes to infertility in part through altered follicular and oocyte development.

  8. Organic Film Photovoltaic Cells with Gadolinium Complex as an Electron Acceptor

    Institute of Scientific and Technical Information of China (English)

    范镝; 初蓓; 李文连; 洪自若

    2004-01-01

    A series of organic photovoltaic (PV) cells in which the electron acceptor and donor are gadolinium (dibenzoylmethanato)3(bathophenanthroline) [Gd(DBM)3bath] and N,N′-diphenyl-N,N′bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine [TPD], respectively, were fabricated. Although TPD acts as an active layer in the bilayered cells, insertion of a Gd-complex film between TPD and the alloy cathode is necessary for efficient carrier photogeneration. Open-circuit voltage of 3.2 V was obtained due to efficient exciton dissociation near the interface between Gd(DBM)3bath and TPD. By incorporating an ultrathin mixed layer of Gd-complex and TPD, external quantum efficiency is improved significantly. Photovoltaic performance of the devices has a common origin, exciplex formation, which results in broadband emission during both photoluminescent and the electroluminescent processes.

  9. A direct electron transfer-based glucose/oxygen biofuel cell operating in human serum

    Energy Technology Data Exchange (ETDEWEB)

    Coman, V.; Gorton, L. [Department of Analytical Chemistry/Biochemistry, Lund University, 22100 Lund (Sweden); Ludwig, R. [Research Centre Applied Biocatalysis, 8010 Graz (Austria); Department of Food Sciences and Technology, BOKU-University of Natural Resources and Applied Life Sciences, 1190 Wien (Austria); Harreither, W.; Haltrich, D. [Department of Food Sciences and Technology, BOKU-University of Natural Resources and Applied Life Sciences, 1190 Wien (Austria); Ruzgas, T. [Biomedical Laboratory Science, Health and Society, Malmoe University, 20506 Malmoe (Sweden); Laboratory of Chemical Enzymology, A.N. Bach Institute of Biochemistry, 119071 Moscow (Russian Federation); Shleev, S.

    2010-02-15

    We report on the fabrication and characterisation of the very first direct electron transfer-based glucose/oxygen biofuel cell (BFC) operating in neutral glucose-containing buffer and human serum. Corynascus thermophilus cellobiose dehydrogenase and Myrothecium verrucaria bilirubin oxidase were used as anodic and cathodic bioelements, respectively. The following characteristics of the mediator-, separator- and membrane-less, a priori, non-toxic and simple miniature BFC, was obtained: an open-circuit voltage of 0.62 and 0.58 V, a maximum power density of ca. 3 and 4 {mu}W cm{sup -2} at 0.37 and 0.19 V of cell voltage, in phosphate buffer and human serum, respectively. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells.

    Science.gov (United States)

    Brinkmann, K O; Zhao, J; Pourdavoud, N; Becker, T; Hu, T; Olthof, S; Meerholz, K; Hoffmann, L; Gahlmann, T; Heiderhoff, R; Oszajca, M F; Luechinger, N A; Rogalla, D; Chen, Y; Cheng, B; Riedl, T

    2017-01-09

    The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and-more importantly-it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.

  11. Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells

    Science.gov (United States)

    Brinkmann, K.O.; Zhao, J.; Pourdavoud, N.; Becker, T.; Hu, T.; Olthof, S.; Meerholz, K.; Hoffmann, L.; Gahlmann, T.; Heiderhoff, R.; Oszajca, M. F.; Luechinger, N. A.; Rogalla, D.; Chen, Y.; Cheng, B.; Riedl, T

    2017-01-01

    The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and—more importantly—it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability. PMID:28067308

  12. A one-compartment fructose/air biological fuel cell based on direct electron transfer.

    Science.gov (United States)

    Wu, Xuee; Zhao, Feng; Varcoe, John R; Thumser, Alfred E; Avignone-Rossa, Claudio; Slade, Robert C T

    2009-10-15

    The construction and characterization of a one-compartment fructose/air biological fuel cell (BFC) based on direct electron transfer is reported. The BFC employs bilirubin oxidase and d-fructose dehydrogenase adsorbed on a cellulose-multiwall carbon nanotube (MWCNT) matrix, reconstituted with an ionic liquid, as the biocathode and the bioanode for oxygen reduction and fructose oxidation reactions, respectively. The performance of the bioelectrode was investigated by chronoamperometric and cyclic voltammetric techniques in a standard three-electrode cell, and the polarization and long-term stability of the BFC was tested by potentiostatic discharge. An open circuit voltage of 663 mV and a maximum power density of 126 microWcm(-2) were obtained in buffer at pH 5.0. Using this regenerated cellulose-MWCNT matrix as the immobilization platform, this BFC has shown a relatively high performance and long-term stability compared with previous studies.

  13. Shape engineering for electronic and optoelectronic properties of Si nanostructure solar cells

    Science.gov (United States)

    He, Yan; Zhao, Yipeng; Quan, Jun; Ouyang, Gang

    2016-10-01

    An analytical model is developed to explore the shape-dependent electronic and optoelectronic properties of silicon nanostructure solar cells, including nanocones (NCs), nanowires (NWs), and truncated-nanocones (TNCs), on the basis of atomic-bond-relaxation consideration and detailed balance principle. It is found that the inhomogeneous NCs can not only make the band gap shrink gradually from the top to the bottom, but also suppress the surface recombination and enhance light absorption. Moreover, the optimal performance of silicon nanostructures can be achieved through modulating the geometrical parameters. Strikingly, the SiNCs show the highest solar conversion efficiency compared with that of NWs and TNCs under identical conditions, which suggest that this kind of nanostructures could be expected to be applicable for the new-typed and friendly alternative solar cell unit.

  14. Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells

    Science.gov (United States)

    Brinkmann, K. O.; Zhao, J.; Pourdavoud, N.; Becker, T.; Hu, T.; Olthof, S.; Meerholz, K.; Hoffmann, L.; Gahlmann, T.; Heiderhoff, R.; Oszajca, M. F.; Luechinger, N. A.; Rogalla, D.; Chen, Y.; Cheng, B.; Riedl, T.

    2017-01-01

    The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and--more importantly--it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.

  15. Planar heterojunction perovskite solar cell based on CdS electron transport layer

    KAUST Repository

    Abulikemu, Mutalifu

    2017-07-02

    We report on planar heterojunction perovskite solar cells employing a metal chalcogenide (CdS) electron transport layer with power conversion efficiency up to 10.8%. The CdS layer was deposited via solution-process chemical bath deposition at low-temperature (60°C). Pinhole-free and uniform thin films were obtained with good structural, optical and morphological properties. An optimal layer thickness of 60nm yielded an improved open-circuit voltage and fill factor compared to the standard TiO2-based solar cells. Devices showed a higher reproducibility of the results compared to TiO2-based ones. We also tested the effect of annealing temperature on the CdS film and the effect of CdCl2 treatment followed by high temperature annealing (410°C) that is expected to passivate the surface, thus eliminating eventual trap-states inducing recombination.

  16. Mitochondrial structure in steroid-producing cells: three-dimensional reconstruction of human Leydig cell mitochondria by electron microscopic tomography.

    Science.gov (United States)

    Prince, Frederick P; Buttle, Karolyn F

    2004-05-01

    Mitochondria of human Leydig cells were reconstructed in three dimension utilizing the technique of electron microscopic tomography to obtain a better understanding of the topology of the internal membrane system and the relationship of these cristae to the inner boundary membrane (IBM). Cristae structure, in many respects, is consistent with previous tomographic studies from typical mitochondria, i.e., mitochondria from nonsteroid-producing cells. Cristae are diverse in form, with well-defined lamellar cristae interconnected to pleomorphic and tubular regions. Occasional fenestrations are present in the lamellar regions. Also consistent with other mitochondria studied by tomography, the openings of the cristae to the IBM (referred to as crista junctions) are roughly circular or elliptical and approximately 20-25 nm in diameter. Morphological contact sites between the outer mitochondrial membrane and IBM are also present. Cristae membranes in these steroid-producing mitochondria are often found in close proximity to the IBM. Unique to steroid-producing mitochondria is a form of the cristae in which multiple lamellae are in very close apposition, previously defined as the lamellar association. Tomographic reconstructions of the lamellar association reveal that these well-organized membranes also open to the IBM via crista junctions. These regions of closely apposed lamellar cristae are also interconnected and display small tubular extensions from the lamellae. The current study is the first electron microscopic tomography study of mitochondria from steroid-producing cells. The results show the cristae interconnect to form an extensive internal membrane system, which is perhaps better termed the cristae compartment. This internal membrane system is notable due to the high surface area with few small openings to the IBM. Such a morphology is more analogous to the thylakoid membrane system of chloroplasts than the long-standing view of mitochondrial cristae. The

  17. Ice formation and development in aged, wintertime cumulus over the UK: observations and modelling

    Directory of Open Access Journals (Sweden)

    I. Crawford

    2012-06-01

    Full Text Available In situ high resolution aircraft measurements of cloud microphysical properties were made in coordination with ground based remote sensing observations of a line of small cumulus clouds, using Radar and Lidar, as part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate (APPRAISE project. A narrow but extensive line (~100 km long of shallow convective clouds over the southern UK was studied. Cloud top temperatures were observed to be higher than −8 °C, but the clouds were seen to consist of supercooled droplets and varying concentrations of ice particles. No ice particles were observed to be falling into the cloud tops from above. Current parameterisations of ice nuclei (IN numbers predict too few particles will be active as ice nuclei to account for ice particle concentrations at the observed, near cloud top, temperatures (−7.5 °C.

    The role of mineral dust particles, consistent with concentrations observed near the surface, acting as high temperature IN is considered important in this case. It was found that very high concentrations of ice particles (up to 100 L−1 could be produced by secondary ice particle production providing the observed small amount of primary ice (about 0.01 L−1 was present to initiate it. This emphasises the need to understand primary ice formation in slightly supercooled clouds. It is shown using simple calculations that the Hallett-Mossop process (HM is the likely source of the secondary ice.

    Model simulations of the case study were performed with the Aerosol Cloud and Precipitation Interactions Model (ACPIM. These parcel model investigations confirmed the HM process to be a very important mechanism for producing the observed high ice concentrations. A key step in generating the high concentrations was the process of collision and coalescence of rain drops, which once formed fell rapidly through the cloud, collecting ice particles which caused them

  18. Biofuel Cells Select for Microbial Consortia That Self-Mediate Electron Transfer

    Science.gov (United States)

    Rabaey, Korneel; Boon, Nico; Siciliano, Steven D.; Verhaege, Marc; Verstraete, Willy

    2004-01-01

    Microbial fuel cells hold great promise as a sustainable biotechnological solution to future energy needs. Current efforts to improve the efficiency of such fuel cells are limited by the lack of knowledge about the microbial ecology of these systems. The purposes of this study were (i) to elucidate whether a bacterial community, either suspended or attached to an electrode, can evolve in a microbial fuel cell to bring about higher power output, and (ii) to identify species responsible for the electricity generation. Enrichment by repeated transfer of a bacterial consortium harvested from the anode compartment of a biofuel cell in which glucose was used increased the output from an initial level of 0.6 W m−2 of electrode surface to a maximal level of 4.31 W m−2 (664 mV, 30.9 mA) when plain graphite electrodes were used. This result was obtained with an average loading rate of 1 g of glucose liter−1 day−1 and corresponded to 81% efficiency for electron transfer from glucose to electricity. Cyclic voltammetry indicated that the enhanced microbial consortium had either membrane-bound or excreted redox components that were not initially detected in the community. Dominant species of the enhanced culture were identified by denaturing gradient gel electrophoresis and culturing. The community consisted mainly of facultative anaerobic bacteria, such as Alcaligenes faecalis and Enterococcus gallinarum, which are capable of hydrogen production. Pseudomonas aeruginosa and other Pseudomonas species were also isolated. For several isolates, electrochemical activity was mainly due to excreted redox mediators, and one of these mediators, pyocyanin produced by P. aeruginosa, could be characterized. Overall, the enrichment procedure, irrespective of whether only attached or suspended bacteria were examined, selected for organisms capable of mediating the electron transfer either by direct bacterial transfer or by excretion of redox components. PMID:15345423

  19. Fluorinated copper phthalocyanine nanowires for enhancing interfacial electron transport in organic solar cells.

    Science.gov (United States)

    Yoon, Seok Min; Lou, Sylvia J; Loser, Stephen; Smith, Jeremy; Chen, Lin X; Facchetti, Antonio; Marks, Tobin J; Marks, Tobin

    2012-12-12

    Zinc oxide is a promising candidate as an interfacial layer (IFL) in inverted organic photovoltaic (OPV) cells due to the n-type semiconducting properties as well as chemical and environmental stability. Such ZnO layers collect electrons at the transparent electrode, typically indium tin oxide (ITO). However, the significant resistivity of ZnO IFLs and an energetic mismatch between the ZnO and the ITO layers hinder optimum charge collection. Here we report that inserting nanoscopic copper hexadecafluorophthalocyanine (F(16)CuPc) layers, as thin films or nanowires, between the ITO anode and the ZnO IFL increases OPV performance by enhancing interfacial electron transport. In inverted P3HT:PC(61)BM cells, insertion of F(16)CuPc nanowires increases the short circuit current density (J(sc)) versus cells with only ZnO layers, yielding an enhanced power conversion efficiency (PCE) of ∼3.6% vs ∼3.0% for a control without the nanowire layer. Similar effects are observed for inverted PTB7:PC(71)BM cells where the PCE is increased from 8.1% to 8.6%. X-ray scattering, optical, and electrical measurements indicate that the performance enhancement is ascribable to both favorable alignment of the nanowire π-π stacking axes parallel to the photocurrent flow and to the increased interfacial layer-active layer contact area. These findings identify a promising strategy to enhance inverted OPV performance by inserting anisotropic nanostructures with π-π stacking aligned in the photocurrent flow direction.

  20. Electron microscopy of primary cell cultures in solution and correlative optical microscopy using ASEM

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Kazumi; Kinoshita, Takaaki [Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577 (Japan); Uemura, Takeshi [Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Motohashi, Hozumi [Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-cho, Aoba-ku, Sendai 980-8575 (Japan); Watanabe, Yohei; Ebihara, Tatsuhiko [Biomedical Research Institute, National Institute of Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566 (Japan); Nishiyama, Hidetoshi [JEOL Ltd., 1-2 Musashino 3-chome, Akishima, Tokyo 196-8558 (Japan); Sato, Mari [Biomedical Research Institute, National Institute of Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566 (Japan); Suga, Mitsuo [JEOL Ltd., 1-2 Musashino 3-chome, Akishima, Tokyo 196-8558 (Japan); Maruyama, Yuusuke; Tsuji, Noriko M. [Biomedical Research Institute, National Institute of Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566 (Japan); Yamamoto, Masayuki [Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai 980-8575 (Japan); Nishihara, Shoko, E-mail: shoko@soka.ac.jp [Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577 (Japan); Sato, Chikara, E-mail: ti-sato@aist.go.jp [Biomedical Research Institute, National Institute of Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566 (Japan)

    2014-08-01

    Correlative light-electron microscopy of cells in a natural environment of aqueous liquid facilitates high-throughput observation of protein complex formation. ASEM allows the inverted SEM to observe the wet sample from below, while an optical microscope observes it from above quasi-simultaneously. The disposable ASEM dish with a silicon nitride (SiN) film window can be coated variously to realize the primary-culture of substrate-sensitive cells in a few milliliters of culture medium in a stable incubator environment. Neuron differentiation, neural networking, proplatelet-formation and phagocytosis were captured by optical or fluorescence microscopy, and imaged at high resolution by gold-labeled immuno-ASEM with/without metal staining. Fas expression on the cell surface was visualized, correlated to the spatial distribution of F-actin. Axonal partitioning was studied using primary-culture neurons, and presynaptic induction by GluRδ2-N-terminus-linked fluorescent magnetic beads was correlated to the presynaptic-marker Bassoon. Further, megakaryocytes secreting proplatelets were captured, and P-selectins with adherence activity were localized to some of the granules present by immuno-ASEM. The phagocytosis of lactic acid bacteria by dendritic cells was also imaged. Based on these studies, ASEM correlative microscopy promises to allow the study of various mesoscopic-scale dynamics in the near future. - Highlights: • In situ correlative light electron microscopy of samples in open solution by ASEM. • Primary cultures for in-solution CLEM by developing SiN-film coating methods • First visualization of fluorescent magnetic beads in aqueous solution by CLEM. • Presynaptic induction of neurons by GluRδ2-N-terminus-coated beads studied by CLEM. • Axonal partitioning, bacterial phagocytosis, platelet formation imaged by CLEM.

  1. Different Cell Types In the Lower Respiratory Tract of the Reindeer (Rangifer tarandus tarandus L. - A Transmission Electron Microscopical Study

    Directory of Open Access Journals (Sweden)

    Seppo A.m. Saari

    1997-02-01

    Full Text Available The epithelium of the trachea and distal airways of 12 healthy adult reindeer were studied with transmission electron microscopy. The ultrastructure of the reindeer respiratory tract corresponded to the findings of previous investigators studying other mammalian species. The epithelium of the trachea and bronchi, down to the level of the distal bronchioli, was composed of three main types of cell: ciliated, goblet, and basal. In the distal brochioli, non-ciliated cells similar to those known as Clara cells were predominant. Numerous electron-dense granules and the cell organelle pattern resembled the Clara cell type observed in laboratory rodents, rabbit, sheep, pig, horse, and llama. Pneumocyte 1 and pneumocyte 2 cells were readily identified in the alveoli. The pneumocyte 2 cells possessed short microvilli and granules with lamellar content. Micropinocytotic vesicles were very numerous in the alveolar wall, and a small number of alveolar macrophages occasionally seen in the alveolar lumen.

  2. Correlative fluorescence and scanning transmission electron microscopy of quantum dot-labeled proteins on whole cells in liquid.

    Science.gov (United States)

    Peckys, Diana B; Bandmann, Vera; de Jonge, Niels

    2014-01-01

    Correlative fluorescence microscopy combined with scanning transmission electron microscopy (STEM) of cells fully immersed in liquid is a new methodology with many application areas. Proteins, in live cells immobilized on microchips, are labeled with fluorescent quantum dot nanoparticles. In this protocol, the epidermal growth factor receptor (EGFR) is labeled. The cells are fixed after a selected labeling time, for example, 5 min as needed to form EGFR dimers. The microchip with cells is then imaged with fluorescence microscopy. Thereafter, STEM can be accomplished in two ways. The microchip with the labeled cells and one microchip with a spacer are assembled into a special microfluidic device and imaged with dedicated high-voltage STEM. Alternatively, thin edges of cells can be studied with environmental scanning electron microscopy with a STEM detector, by placing a microchip with cells in a cooled wet environment.

  3. Porous cathode optimization for lithium cells: Ionic and electronic conductivity, capacity, and selection of materials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.-H.; Wang, C.-W.; Zhang, X. [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125 (United States); Sastry, A.M. [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125 (United States); Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2125 (United States); Department of Material Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2125 (United States)

    2010-05-01

    Narrowing the gap between theoretical and actual capacity in key Li-based battery systems can be achieved through improvements in both electronic and ionic conductivities of materials, via addition of conductive species. Additives do, however, penalize both volumetric and gravimetric properties, and also limit liquid transport and high rate performance. In this work, we developed a technique to design and optimize cathode system based directly on the relationships among ionic and electronic conductivities and specific energy, for a range of commercially viable cathode electrochemistries and additives. Our results quantify trade-offs among ionic and electronic conductivity, and conductivity and specific energy. We also provide quantitative relationships for improved utilization and specific power, with higher specific energy. Finally, we provide quantitative guidance for the design of high energy density Li(Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3})O{sub 2} cells using conductive additives, and also provide guidelines for the design of cathode systems, based directly on solid and liquid phase transport limitations. Future work will focus on higher rates of performance, and will be based on analyses here. (author)

  4. Optimizing electronic standard cell libraries for variability tolerance through the nano-CMOS grid.

    Science.gov (United States)

    Walker, James Alfred; Sinnott, Richard; Stewart, Gordon; Hilder, James A; Tyrrell, Andy M

    2010-08-28

    The project Meeting the Design Challenges of nano-CMOS Electronics (http://www.nanocmos.ac.uk) was funded by the Engineering and Physical Sciences Research Council to tackle the challenges facing the electronics industry caused by the decreasing scale of transistor devices, and the inherent variability that this exposes in devices and in the circuits and systems in which they are used. The project has developed a grid-based solution that supports the electronics design process, incorporating usage of large-scale high-performance computing (HPC) resources, data and metadata management and support for fine-grained security to protect commercially sensitive datasets. In this paper, we illustrate how the nano-CMOS (complementary metal oxide semiconductor) grid has been applied to optimize transistor dimensions within a standard cell library. The goal is to extract high-speed and low-power circuits which are more tolerant of the random fluctuations that will be prevalent in future technology nodes. Using statistically enhanced circuit simulation models based on three-dimensional atomistic device simulations, a genetic algorithm is presented that optimizes the device widths within a circuit using a multi-objective fitness function exploiting the nano-CMOS grid. The results show that the impact of threshold voltage variation can be reduced by optimizing transistor widths, and indicate that a similar method could be extended to the optimization of larger circuits.

  5. Particle-in-cell study of the ion-to-electron sheath transition

    CERN Document Server

    Scheiner, Brett; Hopkins, Matthew M; Yee, Benjamin T; Barnat, Edward V

    2016-01-01

    The form of a sheath near a small electrode, with bias changing from below to above the plasma potential is studied using 2D particle-in-cell (PIC) simulations. Five cases are studied: (A) an electrode biased more than the electron temperature ($T_e/e$) below the plasma potential, (B) an electrode biased less than $T_e/2e$ below the plasma potential, (C) an electrode biased nearly at the plasma potential, (D) an electrode biased more than $T_i/2e$ but less than $T_e/2e$ above the plasma potential, and (E) an electrode biased much greater than $T_e/2e$ above the plasma potential. In case (A), the electron velocity distribution function (EVDF) is observed to be Maxwellian with a Boltzmann-type exponential density decay through the ion sheath and presheath. In cases (B) and (C), the EVDFs exhibit a loss-cone type truncation due to fast electrons overcoming the small potential difference between the electrode and plasma. No sheath is present in this regime, and the plasma remains quasineutral up to the electrode....

  6. Grafted organic monolayer for single electron transport and for quantum dots solar cells

    Science.gov (United States)

    Caillard, Louis Marie

    Functionalization of oxide-free silicon and silicon oxide surfaces is important for a number of applications. In this work, organic monolayers are grafted (GOM) on oxide-free silicon surfaces using thermal and ultraviolet-activated hydrosilylation of hydrogen-terminated silicon surfaces, primarily using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy for characterization. The resulting amine-terminated GOM have been used for depositing nanoparticles, selecting the end group for two very specific applications: single electron devices and nano-quantum-dot (NQD) enhanced Si photovoltaic cells. To perform single-electron transport measurements, colloidal gold nanoparticles have been deposited on amine-functionalized silicon surfaces and tunneling measurements performed with a scanning tunneling microscope in an ultra-high vacuum chamber. Using a double-barrier tunneling junction (with the GOM as the first barrier and the vacuum between the scanning tip and the gold nanoparticle as the second one), single-electron transport was observed at 30K through a Coulomb staircase phenomenon. The critical parameters were identified to improve reproducibility. Finally, recently developed advanced modeling, based on traditional "orthodox" theory, was optimized to account for the observations (e.g. I-V dependence on band bending). This work provides a basis for the development of single-electron transistors that are compatible with current silicon based technology. To enhance standard silicon-based solar cells, GOM is also needed to graft strongly absorbing II-VI NQDs and optimize their energy transfer to the silicon substrate. Recent photoluminescence spectroscopy has demonstrated that energy transfer occurs through both radiative and non-radiative mechanisms between NQDs and the substrate. With grafting technology, the aim was to optimize absorption, as probed by photoluminescence, in two ways. First, silicon nanopillars were fabricated to increase the

  7. Solution-Processed Nb:SnO2 Electron Transport Layer for Efficient Planar Perovskite Solar Cells.

    Science.gov (United States)

    Ren, Xiaodong; Yang, Dong; Yang, Zhou; Feng, Jiangshan; Zhu, Xuejie; Niu, Jinzhi; Liu, Yucheng; Zhao, Wangen; Liu, Shengzhong Frank

    2017-01-25

    Electron transport layer (ETL), facilitating charge carrier separation and electron extraction, is a key component in planar perovskite solar cells (PSCs). We developed an effective ETL using low-temperature solution-processed Nb-doped SnO2 (Nb:SnO2). Compared to the pristine SnO2, the power conversion efficiency of PSCs based on Nb:SnO2 ETL is raised to 17.57% from 15.13%. The splendid performance is attributed to the excellent optical and electronic properties of the Nb:SnO2 material, such as smooth surface, high electron mobility, appropriate electrical conductivity, therefore making a better growth platform for a high quality perovskite absorber layer. Experimental analyses reveal that the Nb:SnO2 ETL significantly enhances the electron extraction and effectively suppresses charge recombination, leading to improved solar cell performance.

  8. Preparation of electron buffer layer with crystalline ZnO nanoparticles in inverted organic photovoltaic cells

    Science.gov (United States)

    Lee, Donghwan; Kang, Taeho; Choi, Yoon-Young; Oh, Seong-Geun

    2017-06-01

    Zinc oxide (ZnO) nanoparticles synthesized through sol-gel method were used to fabricate the electron buffer layer in inverted organic photovoltaic cells (OPVs) after thermal treatment. To investigate the effect of thermal treatment on the formation of crystalline ZnO nanoparticles, the amorphous ZnO nanoparticles were treated via hydrothermal method. The crystalline phase of ZnO with well-ordered structure could be obtained when the amorphous phase of ZnO was processed under hydrothermal treatment at 170 °C. The crystalline structure of ZnO thin film in inverted organic solar cell could be obtained under relatively low annealing temperature by using thermally treated ZnO nanoparticles. The OPVs fabricated by using crystalline ZnO nanoparticles for electron buffer layer exhibited higher efficiency than the conventional ZnO nanoparticles. The best power conversion efficiency (PCE) was achieved for 7.16% through the ZnO film using the crystalline ZnO nanoparticles. The proposed method to prepared ZnO nanoparticles (NPs) could effectively reduce energy consumption during the fabrication of OPVs, which would greatly contribute to advantages such as lower manufacturing costs, higher productivity and application on flexible substrates.

  9. Electrical performance of the InGaP solar cell irradiated with low energy electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, Yasuki; Okuda, Shuichi; Kojima, Takeo; Oka, Takashi [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai City, Osaka (Japan); Kawakita, Shirou; Imaizumi, Mitsuru; Kusawake, Hiroaki [Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba, Ibaraki (Japan)

    2015-06-15

    The investigation of the radiation degradation characteristics of InGaP space solar cells is important. In order to understand the mechanism of the degradation by radiation the samples of the InGaP solar cell were irradiated in vacuum and at ambient temperature with electron beams from a Cockcroft-Walton type accelerator at Osaka Prefecture University. The threshold energies for recoil were obtained by theoretical calculation. The energies and the fluences of the electron beams were from 60 to 400 keV and from 3 x 10{sup 14} to 3 x 10{sup 16} cm{sup -2}, respectively. The light-current-voltage measurements were performed. The degradation of Isc caused by the defects related to the phosphorus atoms was observed and the degradation was suppressed by irradiation at an energy higher than the threshold energy for recoiling Indium atoms. At an energy of 60 keV, where the recoil does not occur, the V{sub oc} was degraded. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Particle-In-Cell Simulation of Electron Acceleration in Solar Coronal Jets

    CERN Document Server

    Baumann, G

    2012-01-01

    We investigate electron acceleration resulting from 3D magnetic reconnection between an emerging, twisted magnetic flux rope and a pre-existing weak, open magnetic field. We first follow the rise of an unstable, twisted flux tube with a resistive MHD simulation where the numerical resolution is enhanced by using fixed mesh refinement. As in previous MHD investigations of similar situations the rise of the flux tube into the pre-existing inclined coronal magnetic field results in the formation of a solar coronal jet. A snapshot of the MHD model is then used as an initial and boundary condition for a particle-in-cell simulation, using up to half a billion cells and over 20 billion charged particle. Particle acceleration occurs mainly in the reconnection current sheet, with accelerated electrons displaying a power law dN/dE distribution with an index of about -1.65. The main acceleration mechanism is a systematic electric field, striving to maintaining the electric current in the current sheet against losses cau...

  11. Mesoporous SnO₂ single crystals as an effective electron collector for perovskite solar cells.

    Science.gov (United States)

    Zhu, Zonglong; Zheng, Xiaoli; Bai, Yang; Zhang, Teng; Wang, Zilong; Xiao, Shuang; Yang, Shihe

    2015-07-28

    Mesoporous single crystals are prized for their fast electron transport and high surface area. Here we report the first synthesis of mesoporous SnO2 single crystals (SnO2 MSCs) by a simple silica-templated hydrothermal method, and its application in solution-processed perovskite solar cells (PSCs). A relatively low efficiency (3.76%) was obtained due to the strong charge recombination at the SnO2/perovskite interface. However, by coating a thin TiO2 barrier layer on SnO2via TiCl4 treatment, we were able to achieve an 8.54% power conversion efficiency (PCE). A dynamics study using impedance spectroscopy revealed a much lower transport resistance for the SnO2 MSC-based solar cells than for the TiO2 nanocrystal PSCs, but a stronger recombination. Significantly, the thin TiO2 coating layer on SnO2 considerably reduced the recombination while largely maintaining the superior electron-transport properties.

  12. Decellularized human Schneiderian membrane: electron microscopic study as a bioscaffold and preliminary cell seeding.

    Science.gov (United States)

    Rahpeyma, Amin; Khajehahmadi, Saeedeh; Khalife, Hussein H

    2014-12-01

    Perforation of maxillary sinus mucous membrane is one of the most prevalent complications during open sinus lift surgery. Moreover, such complication can usually be managed by an absorbable membrane. As far as absorbable membranes are concerned, decellularized maxillary sinus mucous membrane, which is an extracellular matrix, can be used as a biologic scaffold and an insulating membrane in sinus lifting surgery. The decellularization process of the maxillary sinus membrane was performed by means of physical and chemical procedures (liquid nitrogen and sodium dodecyl sulfate). Then this membrane was used as a bioscaffold for culturing with adult mesenchymal stem cells, which were derived from adipose tissue. Histologic evaluation of the decellularized scaffold revealed that cells of the Schneiderian membrane were compatibly removed via SDS 1%. Moreover, the scan with electron microscope (S6N - Leo vp1450, Germany) of the scaffold indicated that the collagen fibers of the decellularized maxillary sinus membrane were intact. Furthermore, the culture studies carried out showed that this scaffold supported cell seeding. The decellularized human maxillary Schneiderian membrane has a 3D structure similar to that of the extracellular matrix of human normal tissues. As a matter of fact, it can be used as a bioscaffold to support cell seeding. Copyright © 2014 Elsevier GmbH. All rights reserved.

  13. Multi-resolution correlative focused ion beam scanning electron microscopy: applications to cell biology.

    Science.gov (United States)

    Narayan, Kedar; Danielson, Cindy M; Lagarec, Ken; Lowekamp, Bradley C; Coffman, Phil; Laquerre, Alexandre; Phaneuf, Michael W; Hope, Thomas J; Subramaniam, Sriram

    2014-03-01

    Efficient correlative imaging of small targets within large fields is a central problem in cell biology. Here, we demonstrate a series of technical advances in focused ion beam scanning electron microscopy (FIB-SEM) to address this issue. We report increases in the speed, robustness and automation of the process, and achieve consistent z slice thickness of ∼3 nm. We introduce "keyframe imaging" as a new approach to simultaneously image large fields of view and obtain high-resolution 3D images of targeted sub-volumes. We demonstrate application of these advances to image post-fusion cytoplasmic intermediates of the HIV core. Using fluorescently labeled cell membranes, proteins and HIV cores, we first produce a "target map" of an HIV infected cell by fluorescence microscopy. We then generate a correlated 3D EM volume of the entire cell as well as high-resolution 3D images of individual HIV cores, achieving correlative imaging across a volume scale of 10(9) in a single automated experimental run.

  14. Perspectives on low voltage transmission electron microscopy as applied to cell biology.

    Science.gov (United States)

    Bendayan, Moise; Paransky, Eugene

    2014-12-01

    Low voltage transmission electron microscopy (LVTEM) with accelerating voltages as low as 5 kV was applied to cell biology. To take advantage of the increased contrast given by LVTEM, tissue preparation was modified omitting all heavy metals such as osmium, uranium, and lead from the fixation, on block staining and counterstaining. Nonstained ultra-thin tissue sections (40 nm thick) generated highly contrasted images. While the aspect of the cells remains similar to that obtained by conventional TEM, some new substructures were revealed. The pancreatic acinar cells granules present a heterogeneous matrix with partitions corresponding to segregation of their different secretory proteins. Microvilli display their core of microfilaments anchored to the dense top membrane. Mitochondria revealed the presence of distinct particles along their cristea membranes that may correspond to the ATP synthase complexes or oxysomes. The dense nuclear chromatin displays a honey-comb appearance while distinct beads aligned along thin threads were seen in the dispersed chromatin. These new features revealed by LVTEM correlate with structures described or predicted through other approaches. Masking effects due to thickness of the tissue sections and to the presence of heavy metals must have prevented their observation by conventional TEM. Furthermore, the immunogold was adapted to LVTEM revealing nuclear lamin-A at the edge of the dense chromatin ribbons. Combining cytochemistry with LVTEM brings additional advantages to this new approach in cell biology.

  15. Electron tomography of fusiform vesicles and their organization in urothelial cells.

    Directory of Open Access Journals (Sweden)

    Samo Hudoklin

    Full Text Available The formation of fusiform vesicles (FVs is one of the most distinctive features in the urothelium of the urinary bladder. FVs represent compartments for intracellular transport of urothelial plaques, which modulate the surface area of the superficial urothelial (umbrella cells during the distension-contraction cycle. We have analysed the three-dimensional (3D structure of FVs and their organization in umbrella cells of mouse urinary bladders. Compared to chemical fixation, high pressure freezing gave a new insight into the ultrastructure of urothelial cells. Electron tomography on serial sections revealed that mature FVs had a shape of flattened discs, with a diameter of up to 1.2 µm. The lumen between the two opposing asymmetrically thickened membranes was very narrow, ranging from 5 nm to 10 nm. Freeze-fracturing and immunolabelling confirmed that FVs contain two opposing urothelial plaques connected by a hinge region that made an omega shaped curvature. In the central cytoplasm, 4-15 FVs were often organized into stacks. In the subapical cytoplasm, FVs were mainly organized as individual vesicles. Distension-contraction cycles did not affect the shape of mature FVs; however, their orientation changed from parallel in distended to perpendicular in contracted bladder with respect to the apical plasma membrane. In the intermediate cells, shorter and more dilated immature FVs were present. The salient outcome from this research is the first comprehensive, high resolution 3D view of the ultrastructure of FVs and how they are organized differently depending on their location in the cytoplasm of umbrella cells. The shape of mature FVs and their organization into tightly packed stacks makes them a perfect storage compartment, which transports large amounts of urothelial plaques while occupying a small volume of umbrella cell cytoplasm.

  16. Particle-in-cell simulations of the relaxation of electron beams in inhomogeneous solar wind plasmas

    Science.gov (United States)

    Thurgood, Jonathan O.; Tsiklauri, David

    2016-12-01

    Previous theoretical considerations of electron beam relaxation in inhomogeneous plasmas have indicated that the effects of the irregular solar wind may account for the poor agreement of homogeneous modelling with the observations. Quasi-linear theory and Hamiltonian models based on Zakharov's equations have indicated that when the level of density fluctuations is above a given threshold, density irregularities act to de-resonate the beam-plasma interaction, restricting Langmuir wave growth on the expense of beam energy. This work presents the first fully kinetic particle-in-cell (PIC) simulations of beam relaxation under the influence of density irregularities. We aim to independently determine the influence of background inhomogeneity on the beam-plasma system, and to test theoretical predictions and alternative models using a fully kinetic treatment. We carry out one-dimensional (1-D) PIC simulations of a bump-on-tail unstable electron beam in the presence of increasing levels of background inhomogeneity using the fully electromagnetic, relativistic EPOCH PIC code. We find that in the case of homogeneous background plasma density, Langmuir wave packets are generated at the resonant condition and then quasi-linear relaxation leads to a dynamic increase of wavenumbers generated. No electron acceleration is seen - unlike in the inhomogeneous experiments, all of which produce high-energy electrons. For the inhomogeneous experiments we also observe the generation of backwards-propagating Langmuir waves, which is shown directly to be due to the refraction of the packets off the density gradients. In the case of higher-amplitude density fluctuations, similar features to the weaker cases are found, but also packets can also deviate from the expected dispersion curve in -space due to nonlinearity. Our fully kinetic PIC simulations broadly confirm the findings of quasi-linear theory and the Hamiltonian model based on Zakharov's equations. Strong density fluctuations

  17. Highly efficient uniform ZnO nanostructures for an electron transport layer of inverted organic solar cells.

    Science.gov (United States)

    Kim, Sarah; Kim, Chul-Hyun; Lee, Sang Kyu; Jeong, Jun-Ho; Lee, Jihye; Jin, Sung-Ho; Shin, Won Suk; Song, Chang Eun; Choi, Jun-Hyuk; Jeong, Jong-Ryul

    2013-07-11

    A highly uniform and predesigned ZnO nanostructure fabricated by single step direct nanoimprinting was used as the efficient electron transport layer (ETL) in inverted bulk heterojunction organic solar cells. Improved photovoltaic cell efficiency with long-term stability can be observed due to the large interface between the active layer and nanostructured ZnO ETL.

  18. Organ-to-Cell-Scale Health Assessment Using Geographical Information System Approaches with Multibeam Scanning Electron Microscopy.

    Science.gov (United States)

    Knothe Tate, Melissa L; Zeidler, Dirk; Pereira, André F; Hageman, Daniel; Garbowski, Tomasz; Mishra, Sanjay; Gardner, Lauren; Knothe, Ulf R

    2016-07-01

    This study combines novel multibeam electron microscopy with a geographical information system approach to create a first, seamless, navigable anatomic map of the human hip and its cellular inhabitants. Using spatial information acquired by localizing relevant map landmarks (e.g. cells, blood vessels), network modeling will enable disease epidemiology studies in populations of cells inhabiting tissues and organs.

  19. Structural Integration of Silicon Solar Cells and Lithium-ion Batteries Using Printed Electronics

    Science.gov (United States)

    Kang, Jin Sung

    Inkjet printing of electrode using copper nanoparticle ink is presented. Electrode was printed on a flexible glass epoxy composite substrate using drop on demand piezoelectric dispenser and was sintered at 200°C in N 2 gas condition. The printed electrodes were made with various widths and thicknesses. Surface morphology of electrode was analyzed using scanning electron microscope (SEM) and atomic force microscope (AFM). Reliable dimensions for printed electronics were found from this study. Single-crystalline silicon solar cells were tested under four-point bending to find the feasibility of directly integrating them onto a carbon fiber/epoxy composite laminate. These solar cells were not able to withstand 0.2% strain. On the other hand, thin-film amorphous silicon solar cells were subjected to flexural fatigue loadings. The current density-voltage curves were analyzed at different cycles, and there was no noticeable degradation on its performance up to 100 cycles. A multifunctional composite laminate which can harvest and store solar energy was fabricated using printed electrodes. The integrated printed circuit board (PCB) was co-cured with a carbon/epoxy composite laminate by the vacuum bag molding process in an autoclave; an amorphous silicon solar cell and a thin-film solid state lithium-ion (Li-ion) battery were adhesively joined and electrically connected to a thin flexible PCB; and then the passive components such as resistors and diodes were electrically connected to the printed circuit board by silver pasting. Since a thin-film solid state Li-ion battery was not able to withstand tensile strain above 0.4%, thin Li-ion polymer batteries were tested under various mechanical loadings and environmental conditions to find the feasibility of using the polymer batteries for our multifunctional purpose. It was found that the Li-ion polymer batteries were stable under pressure and tensile loading without any noticeable degradation on its charge and discharge

  20. Hydrostatic Pressure Affects In Vitro Maturation of Oocytes and Follicles and Increases Granulosa Cell Death

    Directory of Open Access Journals (Sweden)

    Isac Karimi

    2013-01-01

    Full Text Available Objective: This study examines the effects of hydrostatic pressure on in vitro maturation (IVM of oocytes derived from in vitro grown follicles.Materials and Methods: In this experimental study, preantral follicles were isolated from 12-day-old female NMRI mice. Each follicle was cultured individually in Alpha Minimal Essential Medium (α-MEM under mineral oil for 12 days. Then, follicles were induced for IVM and divided into two groups, control and experiment. In the experiment group follicles were subjected to 20 mmHg pressure for 30 minutes and cultured for 24-48 hours. We assessed for viability and IVM of the oocytes. The percentage of apoptosis in cumulus cells was determined by the TUNEL assay. A comparison between groups was made using the student’s t test.Results: The percentage of metaphase II oocytes (MII increased in hydrostatic pressure-treated follicles compared to controls (p<0.05. Cumulus cell viability reduced in hydrostatic pressure-treated follicles compared to controls (p<0.05. Exposure of follicles to pressure increased apoptosis in cumulus cells compared to controls (p<0.05.Conclusion: Hydrostatic pressure, by inducing apoptosis in cumulus cells, participates in the cumulus oocyte coupled relationship with oocyte maturation.

  1. Impact of Horizontal Resolution and Cumulus Parameterization Scheme on the Simulation of Heavy Rainfall Events over the Korean Peninsula

    Institute of Scientific and Technical Information of China (English)

    Seung-Woo LEE; Dong-Kyou LEE; Dong-Eon CHANG

    2011-01-01

    In this paper, we present the results from high-resolution numerical simulations of three heavy rainfall events over the Korean Peninsula. The numerical results show that the prediction accuracy for heavy rainfall events improved as horizontal resolution increased. The fine-grid precipitation fields were much closer to the real precipitation fields in the case of large synoptic forcing over the Korean Peninsula. In the case of large convective available potential energy and weak synoptic forcing, it seems that even when using a high resolution, the models still showed poor performance in reproducing the observed high precipitation amounts. However, activation of the cumulus parameterization scheme in the intermediate resolution of 9 km, even at a grid spacing of 3 km, had a positive impact on the simulation of the heavy rainfall event.

  2. Impact of subgrid-scale radiative heating variability on the stratocumulus-to-trade cumulus transition in climate models

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Heng; Gustafson, William I.; Wang, Hailong

    2014-04-29

    Subgrid-scale interactions between turbulence and radiation are potentially important for accurately reproducing marine low clouds in climate models. To better understand the impact of these interactions, the Weather Research and Forecasting (WRF) model is configured for large eddy simulation (LES) to study the stratocumulus-to-trade cumulus (Sc-to-Cu) transition. Using the GEWEX Atmospheric System Studies (GASS) composite Lagrangian transition case and the Atlantic Trade Wind Experiment (ATEX) case, it is shown that the lack of subgrid-scale turbulence-radiation interaction, as is the case in current generation climate models, accelerates the Sc-to-Cu transition. Our analysis suggests that in cloud-topped boundary layers subgrid-scale turbulence-radiation interactions contribute to stronger production of temperature variance, which in turn leads to stronger buoyancy production of turbulent kinetic energy and helps to maintain the Sc cover.

  3. The potential impact of turbulent velocity fluctuations on drizzle formation in Cumulus clouds in an idealized 2D setup

    CERN Document Server

    Andrejczuk, M; Blyth, A

    2015-01-01

    This article discusses a potential impact of turbulent velocity fluctuations of the air on a drizzle formation in Cumulus clouds. Two different representations of turbulent velocity fluctuations for a microphysics formulated in a Lagrangian framework are discussed - random walk model and the interpolation, and its effect on microphysical properties of the cloud investigated. Turbulent velocity fluctuations significantly enhances velocity differences between colliding droplets, especially those having small sizes. As a result drizzle forms faster in simulations including a representation of turbulence. Both representations of turbulent velocity fluctuations, random walk and interpolation, have similar effect on droplet spectrum evolution, but interpolation of the velocity does account for a possible anisotropy in the air velocity. All discussed simulations show relatively large standard deviation ($\\sim$1${\\mu}m$) of the cloud droplet distribution from the onset of cloud formation is observed. Because coalesen...

  4. Acinic cell carcinoma arising in the glossopalatine glands: a report of two cases with electron microscopic observations.

    Science.gov (United States)

    Inoue, T; Shimono, M; Yamamura, T; Saito, I; Watanabe, O; Kawahara, H

    1984-04-01

    Two cases of acinic cell carcinoma arising in the glossopalatine glands were examined with the electron microscope by means of conventional thin sectioning and freeze-fracturing. Light and electron microscopic observation revealed that the tumors consisted of three types of cells: serous-type, ductlike, and vacuolated cells. Serous-type cells had numerous secretory granules, some of which were discharged into the intercellular spaces. Ductlike cells were smaller, usually lacked secretory granules, and were similar to intercalated duct cells. Vacuolated cells had electron-opaque vacuoles in the cytoplasm. Our findings supported the hypothesis that acinic cell carcinoma may represent a neoplasm of multipotential duct cells which have differentiated mainly into granulated serous cells. Freeze-fracture images of this tumor revealed that tight junctions were composed of ten or more interlinked strands with elongation of basal frontier strands. These findings suggested that the junctional morphology of the tumor resembled that of developing salivary glands and was associated with the degree of cellular differentiation.

  5. High-resolution, label-free imaging of living cells with direct electron-beam-excitation-assisted optical microscopy.

    Science.gov (United States)

    Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

    2015-06-01

    High spatial resolution microscope is desired for deep understanding of cellular functions, in order to develop medical technologies. We demonstrate high-resolution imaging of un-labelled organelles in living cells, in which live cells on a 50 nm thick silicon nitride membrane are imaged by autofluorescence excited with a focused electron beam through the membrane. Electron beam excitation enables ultrahigh spatial resolution imaging of organelles, such as mitochondria, nuclei, and various granules. Since the autofluorescence spectra represent molecular species, this microscopy allows fast and detailed investigations of cellular status in living cells.

  6. Role of Cumulus Parameterization Scheme on the Diurnal Cycle of Precipitation over Southeast Asia in RegCM4

    Science.gov (United States)

    Lui, Yuk Sing; Tam, Chi Yung Francis; Au-Yeung, Yee Man

    2017-04-01

    This study examines the sensitivity of precipitation simulations over the CORDEX-Southeast Asia (SEA) domain to the cumulus convection scheme used in the Regional Climate Model version 4 (RegCM4). With the ERA-interim reanalysis as lateral boundary conditions, model integrations using the MIT-Emanuel cumulus parameterization scheme, and those using a "mixed convection scheme" (namely with the MIT-Emanuel scheme over ocean and the Grell scheme with Arakawa Schubert-type closure over land), have been carried out for the 2001-2010 period. On the seasonal average, the use of the mixed convection scheme, in comparison to MIT-Emanuel scheme everywhere, improves rainfall simulations over the South China Sea (SCS) by reducing the summer-time wet bias there. On the other hand, runs with the mixed convection scheme under(over)-estimate rainfall over land in Southeastern China (western coastlines of Indochina and the Philippines). For the diurnal variation of precipitation, it is found that the RegCM4 can reproduce well the characteristics of the diurnal cycle (DC) in SEA. Compared with the mixed convection scheme, the MIT-Emanual scheme performs better in reproducing the amplitude and phase of DC over the landside coastal area of Indochina during summer. Empirical Orthogonal Function (EOF) analysis indicates that switching from the MIT-Emanuel scheme to the mixed convection scheme leads to a reduction in importance of the second EOF mode, which corresponds to rainfall peaked in the afternoon (local time). Further analyses reveal that such underestimation is related to increased cloud cover in RegCM4 using the mixed convection scheme; enhanced cloudiness in turn leads to reduced surface air temperature over land and thus reduced convective instability at 1200 and 1500 local time in the model simulations.

  7. Cryo-electron tomography of Marburg virus particles and their morphogenesis within infected cells.

    Science.gov (United States)

    Bharat, Tanmay A M; Riches, James D; Kolesnikova, Larissa; Welsch, Sonja; Krähling, Verena; Davey, Norman; Parsy, Marie-Laure; Becker, Stephan; Briggs, John A G

    2011-11-01

    Several major human pathogens, including the filoviruses, paramyxoviruses, and rhabdoviruses, package their single-stranded RNA genomes within helical nucleocapsids, which bud through the plasma membrane of the infected cell to release enveloped virions. The virions are often heterogeneous in shape, which makes it difficult to study their structure and assembly mechanisms. We have applied cryo-electron tomography and sub-tomogram averaging methods to derive structures of Marburg virus, a highly pathogenic filovirus, both after release and during assembly within infected cells. The data demonstrate the potential of cryo-electron tomography methods to derive detailed structural information for intermediate steps in biological pathways within intact cells. We describe the location and arrangement of the viral proteins within the virion. We show that the N-terminal domain of the nucleoprotein contains the minimal assembly determinants for a helical nucleocapsid with variable number of proteins per turn. Lobes protruding from alternate interfaces between each nucleoprotein are formed by the C-terminal domain of the nucleoprotein, together with viral proteins VP24 and VP35. Each nucleoprotein packages six RNA bases. The nucleocapsid interacts in an unusual, flexible "Velcro-like" manner with the viral matrix protein VP40. Determination of the structures of assembly intermediates showed that the nucleocapsid has a defined orientation during transport and budding. Together the data show striking architectural homology between the nucleocapsid helix of rhabdoviruses and filoviruses, but unexpected, fundamental differences in the mechanisms by which the nucleocapsids are then assembled together with matrix proteins and initiate membrane envelopment to release infectious virions, suggesting that the viruses have evolved different solutions to these conserved assembly steps.

  8. Cryo-electron tomography of Marburg virus particles and their morphogenesis within infected cells.

    Directory of Open Access Journals (Sweden)

    Tanmay A M Bharat

    2011-11-01

    Full Text Available Several major human pathogens, including the filoviruses, paramyxoviruses, and rhabdoviruses, package their single-stranded RNA genomes within helical nucleocapsids, which bud through the plasma membrane of the infected cell to release enveloped virions. The virions are often heterogeneous in shape, which makes it difficult to study their structure and assembly mechanisms. We have applied cryo-electron tomography and sub-tomogram averaging methods to derive structures of Marburg virus, a highly pathogenic filovirus, both after release and during assembly within infected cells. The data demonstrate the potential of cryo-electron tomography methods to derive detailed structural information for intermediate steps in biological pathways within intact cells. We describe the location and arrangement of the viral proteins within the virion. We show that the N-terminal domain of the nucleoprotein contains the minimal assembly determinants for a helical nucleocapsid with variable number of proteins per turn. Lobes protruding from alternate interfaces between each nucleoprotein are formed by the C-terminal domain of the nucleoprotein, together with viral proteins VP24 and VP35. Each nucleoprotein packages six RNA bases. The nucleocapsid interacts in an unusual, flexible "Velcro-like" manner with the viral matrix protein VP40. Determination of the structures of assembly intermediates showed that the nucleocapsid has a defined orientation during transport and budding. Together the data show striking architectural homology between the nucleocapsid helix of rhabdoviruses and filoviruses, but unexpected, fundamental differences in the mechanisms by which the nucleocapsids are then assembled together with matrix proteins and initiate membrane envelopment to release infectious virions, suggesting that the viruses have evolved different solutions to these conserved assembly steps.

  9. Cryo-Electron Tomography of Marburg Virus Particles and Their Morphogenesis within Infected Cells

    Science.gov (United States)

    Kolesnikova, Larissa; Welsch, Sonja; Krähling, Verena; Davey, Norman; Parsy, Marie-Laure; Becker, Stephan; Briggs, John A. G.

    2011-01-01

    Several major human pathogens, including the filoviruses, paramyxoviruses, and rhabdoviruses, package their single-stranded RNA genomes within helical nucleocapsids, which bud through the plasma membrane of the infected cell to release enveloped virions. The virions are often heterogeneous in shape, which makes it difficult to study their structure and assembly mechanisms. We have applied cryo-electron tomography and sub-tomogram averaging methods to derive structures of Marburg virus, a highly pathogenic filovirus, both after release and during assembly within infected cells. The data demonstrate the potential of cryo-electron tomography methods to derive detailed structural information for intermediate steps in biological pathways within intact cells. We describe the location and arrangement of the viral proteins within the virion. We show that the N-terminal domain of the nucleoprotein contains the minimal assembly determinants for a helical nucleocapsid with variable number of proteins per turn. Lobes protruding from alternate interfaces between each nucleoprotein are formed by the C-terminal domain of the nucleoprotein, together with viral proteins VP24 and VP35. Each nucleoprotein packages six RNA bases. The nucleocapsid interacts in an unusual, flexible “Velcro-like” manner with the viral matrix protein VP40. Determination of the structures of assembly intermediates showed that the nucleocapsid has a defined orientation during transport and budding. Together the data show striking architectural homology between the nucleocapsid helix of rhabdoviruses and filoviruses, but unexpected, fundamental differences in the mechanisms by which the nucleocapsids are then assembled together with matrix proteins and initiate membrane envelopment to release infectious virions, suggesting that the viruses have evolved different solutions to these conserved assembly steps. PMID:22110401

  10. Enhanced interfacial electron transfer of inverted perovskite solar cells by introduction of CoSe into the electron-transporting-layer

    Science.gov (United States)

    Chen, Shanshan; Yang, Songwang; Sun, Hong; Zhang, Lu; Peng, Jiajun; Liang, Ziqi; Wang, Zhong-Sheng

    2017-06-01

    To improve the electron transfer at the interface between the perovskite film and the electron-transporting-material (ETM) layer, CoSe doped [6,6]-phenyl C61-butyric acid methyl ester (PCBM) is employed as the ETM layer for the inverted planar perovskite solar cell with NiO as the hole-transporting-material layer. Introduction of CoSe (5.8 wt%) into the PCBM layer improves the conductivity of the ETM layer and decreases the photoluminescence intensity, thus enhancing the interfacial electron extraction and reducing the electron transfer resistance at the perovskite/ETM interface. As a consequence, the power conversion efficiency is enhanced from 11.43% to 14.91% by 30% due to the noted increases in short-circuit current density from 17.95 mA cm-2 to 19.85 mA cm-2 and fill factor from 0.60 to 0.70. This work provides a new strategy to improve the performance of inverted perovskite solar cells.

  11. An Efficient, "Burn in" Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor.

    Science.gov (United States)

    Cha, Hyojung; Wu, Jiaying; Wadsworth, Andrew; Nagitta, Jade; Limbu, Saurav; Pont, Sebastian; Li, Zhe; Searle, Justin; Wyatt, Mark F; Baran, Derya; Kim, Ji-Seon; McCulloch, Iain; Durrant, James R

    2017-09-01

    A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'″-di(2-octyldodecyl)-2,2';5',2″;5″,2'″-quaterthiophen-5,5'″-diyl)] (PffBT4T-2OD) as a donor polymer blended with either the nonfullerene acceptor EH-IDTBR or the fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) as electron acceptors is reported. Inverted PffBT4T-2OD:EH-IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH-IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T-2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T-2OD:PC71 BM solar cells show significant efficiency loss under simulated solar irradiation ("burn in" degradation) due to the trap-assisted recombination through increased photoinduced trap states, PffBT4T-2OD:EH-IDTBR solar cell shows negligible burn in efficiency loss. Furthermore, PffBT4T-2OD:EH-IDTBR solar cells are found to be substantially more stable under 85 °C thermal stress than PffBT4T-2OD:PC71 BM devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Discovery of a new RNA-containing nuclear structure in UVC-induced apoptotic cells by integrated laser electron microscopy.

    Science.gov (United States)

    Karreman, Matthia A; Agronskaia, Alexandra V; Verkleij, Arie J; Cremers, Fons F M; Gerritsen, Hans C; Humbel, Bruno M

    2009-05-01

    Treatment of cells with UVC radiation leads to the formation of DNA cross-links which, if not repaired, can lead to apoptosis. gamma-H2AX and cleaved caspase 3 are proteins formed during UVC-induced DNA damage and apoptosis respectively. The present study sets out to identify early morphological markers of apoptosis using a new method of correlative microscopy, ILEM (integrated laser electron microscopy). Cleaved caspase 3 and gamma-H2AX were immunofluorescently labelled to mark the cells of interest. These cells were subsequently searched in the fluorescence mode of the ILEM and further analysed at high resolution with TEM (transmission electron microscopy). Following the treatment of HUVECs (human umbilical vein endothelial cells) with UVC radiation, in the majority of the cells gamma-H2AX was formed, whereas only in a subset of cells caspase 3 was activated. In severely damaged cells with high levels of gamma-H2AX a round, electron-dense nuclear structure was found, which was hitherto not identified in UV-stressed cells. This structure exists only in nuclei of cells containing cleaved caspase 3 and is present during all stages of the apoptotic process. Energy-loss imaging showed that the nuclear structure accumulates phosphorus, indicating that it is rich in nucleic acids. Because the nuclear structure did not label for DNA and was not affected by regressive EDTA treatment, it is suggested that the UV-induced nuclear structure contains a high amount of RNA. Because the UV-induced nuclear structure was only found in cells labelled for cleaved caspase 3 it is proposed as an electron microscopic marker for all stages of apoptosis. Such a marker will especially facilitate the screening for early apoptotic cells, which lack the well-known hallmarks of apoptosis within a cell population. It also raises new questions on the mechanisms involved in the UV-induced apoptotic pathway.

  13. Visualization of Mesenchymal Stromal Cells in 2Dand 3D-Cultures by Scanning Electron Microscopy with Lanthanide Contrasting.

    Science.gov (United States)

    Novikov, I A; Vakhrushev, I V; Antonov, E N; Yarygin, K N; Subbot, A M

    2017-02-01

    Mesenchymal stromal cells from deciduous teeth in 2D- and 3D-cultures on culture plastic, silicate glass, porous polystyrene, and experimental polylactoglycolide matrices were visualized by scanning electron microscopy with lanthanide contrasting. Supravital staining of cell cultures with a lanthanide-based dye (neodymium chloride) preserved normal cell morphology and allowed assessment of the matrix properties of the carriers. The developed approach can be used for the development of biomaterials for tissue engineering.

  14. Aluminum-Doped Zinc Oxide as Highly Stable Electron Collection Layer for Perovskite Solar Cells.

    Science.gov (United States)

    Zhao, Xingyue; Shen, Heping; Zhang, Ye; Li, Xin; Zhao, Xiaochong; Tai, Meiqian; Li, Jingfeng; Li, Jianbao; Li, Xin; Lin, Hong

    2016-03-01

    Although low-temperature, solution-processed zinc oxide (ZnO) has been widely adopted as the electron collection layer (ECL) in perovskite solar cells (PSCs) because of its simple synthesis and excellent electrical properties such as high charge mobility, the thermal stability of the perovskite films deposited atop ZnO layer remains as a major issue. Herein, we addressed this problem by employing aluminum-doped zinc oxide (AZO) as the ECL and obtained extraordinarily thermally stable perovskite layers. The improvement of the thermal stability was ascribed to diminish of the Lewis acid-base chemical reaction between perovskite and ECL. Notably, the outstanding transmittance and conductivity also render AZO layer as an ideal candidate for transparent conductive electrodes, which enables a simplified cell structure featuring glass/AZO/perovskite/Spiro-OMeTAD/Au. Optimization of the perovskite layer leads to an excellent and repeatable photovoltaic performance, with the champion cell exhibiting an open-circuit voltage (Voc) of 0.94 V, a short-circuit current (Jsc) of 20.2 mA cm(-2), a fill factor (FF) of 0.67, and an overall power conversion efficiency (PCE) of 12.6% under standard 1 sun illumination. It was also revealed by steady-state and time-resolved photoluminescence that the AZO/perovskite interface resulted in less quenching than that between perovskite and hole transport material.

  15. An Efficient, “Burn in” Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor

    KAUST Repository

    Cha, Hyojung

    2017-06-28

    A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3\\'″-di(2-octyldodecyl)-2,2\\';5\\',2″;5″,2\\'″-quaterthiophen-5,5\\'″-diyl)] (PffBT4T-2OD) as a donor polymer blended with either the nonfullerene acceptor EH-IDTBR or the fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) as electron acceptors is reported. Inverted PffBT4T-2OD:EH-IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH-IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T-2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T-2OD:PC71 BM solar cells show significant efficiency loss under simulated solar irradiation (

  16. Power sources for portable electronics and hybrid cars: lithium batteries and fuel cells.

    Science.gov (United States)

    Scrosati, Bruno

    2005-01-01

    The activities in progress in our laboratory for the development of batteries and fuel cells for portable electronics and hybrid car applications are reviewed and discussed. In the case of lithium batteries, the research has been mainly focused on the characterization of new electrode and electrolyte materials. Results related to disordered carbon anodes and improved, solvent-free, as well as gel-type, polymer electrolytes are particularly stressed. It is shown that the use of proper gel electrolytes, in combination with suitable electrode couples, allows the development of new types of safe, reliable, and low-cost lithium ion batteries which appear to be very promising power sources for hybrid vehicles. Some of the technologies proven to be successful in the lithium battery area are readapted for use in fuel cells. In particular, this approach has been followed for the preparation of low-cost and stable protonic membranes to be proposed as an alternative to the expensive, perfluorosulfonic membranes presently used in polymer electrolyte membrane fuel cells (PEMFCs). Copyright 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc

  17. Hypoxia-selective radiosensitization of mammalian cells by nitracrine, an electron-affinic DNA intercalator

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, P.B.; Anderson, R.F.; Wilson, W.R.

    1987-04-01

    NC (1-nitroacridine nitracine) radiosensitization was evaluated in CHO cultures at 4/sup 0/C. Under hypoxia, submicromolar concentrations resulted in sensitization (SER=1.6 at ..mu.. mol dm/sup -3/). In aerobic conditions, a concentration more than 10-fold higher was required. In aerobic cultures, NC radiosensitization was independent of time of exposure. Postirradiation sensitization was not observed under hypoxia. Time dependence of NC uptake and development of radiosensitization were similar, suggesting that sensitization is due to unmetabolized drug. NC was about 1700 times more potent than misonidazole, (accounted for by the electron affinity of NC (E(1) value at pH 7 of -275 mV versus NHE) and by its accumulation in cells to give intracellular concentrations approximately 30 times greater than in the medium. Concentrations of free NC appear to be low in AA8 cells, presumably due to DNA binding. If radioisensitization by NC is due to bound rather than free drug, it is suggested that intercalated NC can interact efficiently with DNA target radicals, despite a binding ratio in the cell, estimated as less than 1 NC molecule/400 base pairs under conditions providing efficient sensitization. (U.K.).

  18. Power electronics for local fuel cell/-battery plants; Leistungselektronik fuer dezentrale Brennstoffzellen/-Batterieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Krykunov, Oleksandr

    2009-10-13

    With their high efficiency and modular structure, fuel cells are an attractive option for decentral power supply. An important component of decentral power supply systems is the power-electronic control element for supply of electric power from the fuel cell to the three-phase electricity grid. Control elements can be constructed of a unidirectional DC/DC converter with a current inverter connnected in series. The investigation focused on the development of the DC/DC converter with minimum constructional and control requirements and optimum adaption of the DC/DC converter to the characteristics of the fuel cell. (orig.) [German] Die Brennstoffzelle stellt mit ihrem hohen Wirkungsgrad und ihrem modularen Aufbau eine attraktive Option fuer die Verwendung in einem dezentralen Energieversorgungssystem dar. Eine wichtige Komponente des dezentralen Energieversorgungssystems sind die leistungselektronischen Stellglieder fuer die Einspeisung der elektrischen Energie aus der Brennstoffzelle in das dreiphasige Netz. Die leistungselektronischen Stellglieder koennen aus einem undirektionalen DC/DC-Wandler und einem nachgeschalteten Wechselrichter realisiert werden. Die Entwicklung des DC/DC-Wandlers mit einem moeglichst geringeren Bauelemente- und Steuerungsaufwand fuer diese leistungselektronischen Stellglieder und die Anpassung des DC/DC-Wandlers an die Eigenschaften der Brennstoffzelle war das Ziel dieser Arbeit. (orig.)

  19. Push–pull effect on the geometries, electronic and optical properties of thiophene based dye-sensitized solar cell materials

    Directory of Open Access Journals (Sweden)

    Ahmad Irfan

    2014-12-01

    Full Text Available Geometries, electronic structure and electronic absorption spectra of thiophene based dye-sensitized solar cells were performed using Density Functional Theory (DFT and time dependent density functional theory (TD-DFT. Different electron donating and electron withdrawing groups have been substituted. Geometries and electronic properties have been computed at B3LYP/6-31G∗∗ and absorption spectra at TD-B3LYP/6-31G∗∗ level of theory. Major change in bond lengths and bond angles occurs in the system where there is electron withdrawing or electron donating groups have been substituted. In SYSTEM-2 and SYSTEM-3 intra charge transfer has been observed. HOMO of SYSTEM-2 and SYSTEM-3 is delocalized on left side while LUMO on right side of the molecule. In SYSTEM-1, HOMO is on left side while LUMO is in the center. The designed systems show two absorption peaks for each of the system. In short, choice of appropriate electron withdrawing and donating groups is very important for improving the performance of dye-sensitized solar cells.

  20. 2D particle-in-cell simulations of the electron drift instability and associated anomalous electron transport in Hall-effect thrusters

    Science.gov (United States)

    Croes, Vivien; Lafleur, Trevor; Bonaventura, Zdeněk; Bourdon, Anne; Chabert, Pascal

    2017-03-01

    In this work we study the electron drift instability in Hall-effect thrusters (HETs) using a 2D electrostatic particle-in-cell (PIC) simulation. The simulation is configured with a Cartesian coordinate system modeling the radial-azimuthal (r{--}θ ) plane for large radius thrusters. A magnetic field, {{B}}0, is aligned along the Oy axis (r direction), a constant applied electric field, {{E}}0, along the Oz axis (perpendicular to the simulation plane), and the {{E}}0× {{B}}0 direction is along the Ox axis (θ direction). Although electron transport can be well described by electron–neutral collisions for low plasma densities, at high densities (similar to those in typical HETs), a strong instability is observed that enhances the electron cross-field mobility; even in the absence of electron–neutral collisions. The instability generates high frequency (of the order of MHz) and short wavelength (of the order of mm) fluctuations in both the azimuthal electric field and charged particle densities, and propagates in the {{E}}0× {{B}}0 direction with a velocity close to the ion sound speed. The correlation between the electric field and density fluctuations (which leads to an enhanced electron–ion friction force) is investigated and shown to be directly responsible for the increased electron transport. Results are compared with a recent kinetic theory, showing good agreement with the instability properties and electron transport.

  1. Effect of Energy Alignment, Electron Mobility, and Film Morphology of Perylene Diimide Based Polymers as Electron Transport Layer on the Performance of Perovskite Solar Cells.

    Science.gov (United States)

    Guo, Qiang; Xu, Yingxue; Xiao, Bo; Zhang, Bing; Zhou, Erjun; Wang, Fuzhi; Bai, Yiming; Hayat, Tasawar; Alsaedi, Ahmed; Tan, Zhan'ao

    2017-03-29

    For organic-inorganic perovskite solar cells (PerSCs), the electron transport layer (ETL) plays a crucial role in efficient electron extraction and transport for high performance PerSCs. Fullerene and its derivatives are commonly used as ETL for p-i-n structured PerSCs. However, these spherical small molecules are easy to aggregate with high annealing temperature and thus induce morphology stability problems. N-type conjugated polymers are promising candidates to overcome these problems due to the tunable energy levels, controllable aggregation behaviors, and good film formation abilities. Herein, a series of perylene diimide (PDI) based polymers (PX-PDIs), which contain different copolymeried units (X), including vinylene (V), thiophene (T), selenophene (Se), dibenzosilole (DBS), and cyclopentadithiophene (CPDT), are introduced as ETL for p-i-n structured PerSCs. The effect of energy alignment, electron mobility, and film morphology of these ETLs on the photovoltaic performance of the PerSCs are fully investigated. Among the PX-PDIs, PV-PDI demonstrates the deeper LUMO energy level, the highly delocalized LUMO electron density, and a better planar structure, making it the best electron transport material for PerSCs. The planar heterojunction PerSC with PV-PDI as ETL achieves a power conversion efficiency (PCE) of 10.14%, among the best values for non-fullerene based PerSCs.

  2. Efficient planar Sb2S3 solar cells using a low-temperature solution-processed tin oxide electron conductor.

    Science.gov (United States)

    Lei, Hongwei; Yang, Guang; Guo, Yaxiong; Xiong, Liangbin; Qin, Pingli; Dai, Xin; Zheng, Xiaolu; Ke, Weijun; Tao, Hong; Chen, Zhao; Li, Borui; Fang, Guojia

    2016-06-28

    Efficient planar antimony sulfide (Sb2S3) heterojunction solar cells have been made using chemical bath deposited (CBD) Sb2S3 as the absorber, low-temperature solution-processed tin oxide (SnO2) as the electron conductor and poly (3-hexylthiophene) (P3HT) as the hole conductor. A solar conversion efficiency of 2.8% was obtained at 1 sun illumination using a planar device consisting of F-doped SnO2 substrate/SnO2/CBD-Sb2S3/P3HT/Au, whereas the solar cells based on a titanium dioxide (TiO2) electron conductor exhibited a power conversion efficiency of 1.9%. Compared with conventional Sb2S3 sensitized solar cells, the high-temperature processed mesoscopic TiO2 scaffold is no longer needed. More importantly, a low-temperature solution-processed SnO2 layer was introduced for electron transportation to substitute the high-temperature sintered dense blocking TiO2 layer. Our planar solar cells not only have simple geometry with fewer steps to fabricate but also show enhanced performance. The higher efficiency of planar Sb2S3 solar cell devices based on a SnO2 electron conductor is attributed to their high transparency, uniform surface, efficient electron transport properties of SnO2, suitable energy band alignment, and reduced recombination at the interface of SnO2/Sb2S3.

  3. Investigation of solar cells fabricated on low-cost silicon sheet materials using 1 MeV electron irradiation

    Science.gov (United States)

    Kachare, A. H.; Hyland, S. L.; Garlick, G. F. J.

    1981-01-01

    The use of high energy electron irradiation is investigated as a controlled means to study in more detail the junction depletion layer processes of solar cells made on various low-cost silicon sheet materials. Results show that solar cells made on Czochralski grown silicon exhibit enhancement of spectral response in the shorter wavelength region when irradiated with high energy electrons. The base region damage can be reduced by subsequent annealing at 450 C which restores the degraded longer wavelength response, although the shorter wavelength enhancement persists. The second diode component of the cell dark forward bias current is also reduced by electron irradiation, while thermal annealing at 450 C without electron irradiation can also produce these same effects. Electron irradiation produces small changes in the shorter wavelength spectral responses and junction improvements in solar cells made on WEB, EFG, and HEM silicon. It is concluded that these beneficial effects on cell characteristics are due to the reduction of oxygen associated deep level recombination centers in the N(+) diffused layer and in the junction.

  4. Investigation of solar cells fabricated on low-cost silicon sheet materials using 1 MeV electron irradiation

    Science.gov (United States)

    Kachare, A. H.; Hyland, S. L.; Garlick, G. F. J.

    1981-01-01

    The use of high energy electron irradiation is investigated as a controlled means to study in more detail the junction depletion layer processes of solar cells made on various low-cost silicon sheet materials. Results show that solar cells made on Czochralski grown silicon exhibit enhancement of spectral response in the shorter wavelength region when irradiated with high energy electrons. The base region damage can be reduced by subsequent annealing at 450 C which restores the degraded longer wavelength response, although the shorter wavelength enhancement persists. The second diode component of the cell dark forward bias current is also reduced by electron irradiation, while thermal annealing at 450 C without electron irradiation can also produce these same effects. Electron irradiation produces small changes in the shorter wavelength spectral responses and junction improvements in solar cells made on WEB, EFG, and HEM silicon. It is concluded that these beneficial effects on cell characteristics are due to the reduction of oxygen associated deep level recombination centers in the N(+) diffused layer and in the junction.

  5. Pristine fullerenes mixed by vacuum-free solution process: Efficient electron transport layer for planar perovskite solar cells

    Science.gov (United States)

    Dai, Si-Min; Tian, Han-Rui; Zhang, Mei-Lin; Xing, Zhou; Wang, Lu-Yao; Wang, Xin; Wang, Tan; Deng, Lin-Long; Xie, Su-Yuan; Huang, Rong-Bin; Zheng, Lan-Sun

    2017-01-01

    Discovery of organic-inorganic hybrid perovskites ignites the dream of next-generation solar cells fabricated by low-cost solution processing. To date, fullerene derivative [6,6]-phenyl-C61- butyric acid methyl ester (PC61BM), is the most prevalently used electron transport layer for high efficiency p-i-n planar heterojunction perovskite solar cells. Compared with PC61BM, pristine fullerenes, such as C60 and C70, have shown superiority of higher electron mobility and much lower costs. Due to the poor solubility and strong tendency to crystallize for pristine fullerenes in solution process, it is still a challenge to deposit compact and continuous film of pristine fullerenes for p-i-n type perovskite solar cells by solution processing. Herein, solution processed pristine fullerenes (C60 and C70) were used as electron transport layers to replace PC61BM in perovskite solar cells with high performance and enhanced stability. Power conversion efficiency of 14.04% was obtained by using mixture of C60 and C70 as electron transport layer, which is comparable to that of PC61BM based device (13.74%). We demonstrated that the strong tendency of pristine fullerenes to crystallize during solvent removal can be largely mitigated by mixing different kinds of pristine fullerenes. These findings implicate pristine fullerenes as promising electron transport layers for high performance perovskite solar cells.

  6. Minority Carrier Electron Traps in CZTSSe Solar Cells Characterized by DLTS and DLOS

    Energy Technology Data Exchange (ETDEWEB)

    Kheraj, V.; Lund, E. A.; Caruso, A. E.; Al-Ajmi, K.; Pruzan, D.; Miskin, C.; Agrawal, R.; Beall, Carolyn; Repins, Ingrid; Scarpulla, M. A.

    2016-11-21

    We report observations of minority carrier interactions with deep levels in 6-8% efficient Cu2ZnSn(S, Se)4 (CZTSSe) devices using conventional and minority deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS). Directly observing defect interactions with minority carriers is critical to understanding the recombination impact of deep levels. In devices with Cu2ZnSn(S, Se)4 nanoparticle ink absorber layers we identify a mid-gap state capturing and emitting minority electrons. It is 590+/-50 meV from the conduction band mobility edge, has a concentration near 1015/cm3, and has an apparent electron capture cross section ~10-14 cm2. We conclude that, while energetically positioned nearly-ideally to be a recombination center, these defects instead act as electron traps because of a smaller hole cross-section. In CZTSe devices produced using coevaporation, we used minority carrier DLTS on traditional samples as well as ones with transparent Ohmic back contacts. These experiments demonstrate methods for unambiguously probing minority carrier/defect interactions in solar cells in order to establish direct links between defect energy level observations and minority carrier lifetimes. Furthermore, we demonstrate the use of steady-state device simulation to aid in the interpretation of DLTS results e.g. to put bounds on the complimentary carrier cross section even in the absence its direct measurement. This combined experimental and theoretical approach establishes rigorous bounds on the impact on carrier lifetime and Voc of defects observed with DLTS as opposed to, for example, assuming that all deep states act as strong recombination centers.

  7. Bio-Electron-Fenton (BEF) process driven by microbial fuel cells for triphenyltin chloride (TPTC) degradation

    Energy Technology Data Exchange (ETDEWEB)

    Yong, Xiao-Yu; Gu, Dong-Yan; Wu, Yuan-Dong [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Bioenergy Research Institute, Nanjing TECH University, Nanjing 211816 (China); Yan, Zhi-Ying [Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology, Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Science, Chengdu 610041 (China); Zhou, Jun; Wu, Xia-Yuan [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Bioenergy Research Institute, Nanjing TECH University, Nanjing 211816 (China); Wei, Ping [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Jia, Hong-Hua [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Bioenergy Research Institute, Nanjing TECH University, Nanjing 211816 (China); Zheng, Tao, E-mail: zhengtao@ms.giec.ac.cn [Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Nengyuan Road, Guangzhou 510640 (China); Yong, Yang-Chun, E-mail: ycyong@ujs.edu.cn [Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2017-02-15

    Graphical abstract: Schematic diagram of the Bio-Electron-Fenton (BEF) process for TPTC degradation. - Highlights: • A Bio-Electro-Fenton process was performed for TPTC degradation. • TPTC removal efficiency achieved 78.32 ± 2.07% within 100 h. • The TPTC degradation rate (0.775 ± 0.021 μmol L{sup −1} h{sup −1}) was much higher than previous reports. - Abstract: The intensive use of triphenyltin chloride (TPTC) has caused serious environmental pollution. In this study, an effective method for TPTC degradation was proposed based on the Bio-Electron-Fenton process in microbial fuel cells (MFCs). The maximum voltage of the MFC with graphite felt as electrode was 278.47% higher than that of carbon cloth. The electricity generated by MFC can be used for in situ generation of H{sub 2}O{sub 2} to a maximum of 135.96 μmol L{sup −1} at the Fe@Fe{sub 2}O{sub 3(*)}/graphite felt composite cathode, which further reacted with leached Fe{sup 2+} to produce hydroxyl radicals. While 100 μmol L{sup −1} TPTC was added to the cathodic chamber, the degradation efficiency of TPTC reached 78.32 ± 2.07%, with a rate of 0.775 ± 0.021 μmol L{sup −1} h{sup −1}. This Bio-Electron-Fenton driving TPTC degradation might involve in Sn−C bonds breaking and the main process is probably a stepwise dephenylation until the formation of inorganic tin and CO{sub 2}. This study provides an energy saving and efficient approach for TPTC degradation.

  8. Electron accumulation on metal nanoparticles in plasmon-enhanced organic solar cells.

    Science.gov (United States)

    Salvador, Michael; MacLeod, Bradley A; Hess, Angela; Kulkarni, Abhishek P; Munechika, Keiko; Chen, Jennifer I L; Ginger, David S

    2012-11-27

    Plasmonic metal nanoparticles have been used to enhance the performance of thin-film devices such as organic photovoltaics based on polymer/fullerene blends. We show that silver nanoprisms accumulate long-lived negative charges when they are in contact with a photoexcited bulk heterojunction blend composed of poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM). We report both the charge modulation and electroabsorption spectra of silver nanoprisms in solid-state devices and compare these spectra with the photoinduced absorption spectra of P3HT/PCBM blends containing silver nanoprisms. We assign a previously unidentified peak in the photoinduced absorption spectra to the presence of photoinduced electrons on the silver nanoprisms. We show that coating the nanoprisms with a 2.5 nm thick insulating layer can completely inhibit this charging. These results may inform methods for limiting metal-mediated losses in plasmonic solar cells.

  9. Analysis of electronic models for solar cells including energy resolved defect densities

    Energy Technology Data Exchange (ETDEWEB)

    Glitzky, Annegret

    2010-07-01

    We introduce an electronic model for solar cells including energy resolved defect densities. The resulting drift-diffusion model corresponds to a generalized van Roosbroeck system with additional source terms coupled with ODEs containing space and energy as parameters for all defect densities. The system has to be considered in heterostructures and with mixed boundary conditions from device simulation. We give a weak formulation of the problem. If the boundary data and the sources are compatible with thermodynamic equilibrium the free energy along solutions decays monotonously. In other cases it may be increasing, but we estimate its growth. We establish boundedness and uniqueness results and prove the existence of a weak solution. This is done by considering a regularized problem, showing its solvability and the boundedness of its solutions independent of the regularization level. (orig.)

  10. Evaluation on direct interspecies electron transfer in anaerobic sludge digestion of microbial electrolysis cell.

    Science.gov (United States)

    Zhao, Zisheng; Zhang, Yaobin; Quan, Xie; Zhao, Huimin

    2016-01-01

    Increase of methanogenesis in methane-producing microbial electrolysis cells (MECs) is frequently believed as a result of cathodic reduction of CO2. Recent studies indicated that this electromethanogenesis only accounted for a little part of methane production during anaerobic sludge digestion. Instead, direct interspecies electron transfer (DIET) possibly plays an important role in methane production. In this study, anaerobic digestion of sludge were investigated in a single-chamber MEC reactor, a carbon-felt supplemented reactor and a common anaerobic reactor to evaluate the effects of DIET on the sludge digestion. The results showed that adding carbon felt into the reactor increased 12.9% of methane production and 17.2% of sludge reduction. Imposing a voltage on the carbon felt further improved the digestion. Current calculation showed that the cathodic reduction only contributed to 27.5% of increased methane production. Microbial analysis indicated that DIET played an important role in the anaerobic sludge digestion in the MEC.

  11. Three-dimensional architecture of hair-cell linkages as revealedby electron-microscopic tomography

    Energy Technology Data Exchange (ETDEWEB)

    Auer, Manfred; Koster, Bram; Ziese, Ulrike; Bajaj, Chandrajit; Volkmann, Niels; Wang, Da Neng; Hudspeth, A. James

    2006-07-28

    The senses of hearing and balance rest upon mechanoelectrical transduction by the hair bundles of hair cells in the inner ear. Located at the apical cellular surface, each hair bundle comprises several tens of stereocilia and a single kinocilium that are interconnected by extracellular proteinaceous links. Using electron-microscopic tomography of bullfrog saccular sensory epithelia, we examined the three-dimensional structures of ankle or basal links, kinociliary links, and tip links. We observed clear differences in the dimensions and appearances of the three links. We found two distinct populations of tip links suggestive of the involvement of two proteins or splice variants. We noted auxiliary links connecting the upper portions of tip links to the taller stereocilia. Tip links and auxiliary links show a tendency to adopt a globular conformation when disconnected from the membrane surface.

  12. Electron microscopy of single-stranded structures in the DNA of competent Haemophilus influenzae cells

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, D.; Kupfer, D.M.

    1987-02-01

    Chromosomal DNAs from exponential-phase and competent cells of Haemophilus influenzae were examined by electron microscopy to determine whether the chromosome undergoes structural changes during competence development. Single-stranded gaps and single-stranded tails formed in chromosomal DNA during competence development. The generation of gaps was dependent on the rec-2 function. Since the rec-2 mutant is defective in the translocation of donor DNA, it was inferred that the gaps were involved in the translocation step of transformation. The generation of single-stranded tails was independent of the rec-1 and rec-2 genes. Therefore, these structures were assumed to play no direct role in the interaction of donor and recipient DNAs during transformation. Gaps were preferentially associated with a readily denaturable, possible A + T-rich fraction of the genome. This finding raised the possibility that hot spots for transformation might be associated with A + T-rich DNA.

  13. Electron transfer mechanisms, new applications, and performance of biocathode microbial fuel cells

    KAUST Repository

    Huang, Liping

    2011-01-01

    Broad application of microbial fuel cells (MFCs) requires low cost and high operational sustainability. Microbial-cathode MFCs, or cathodes using only bacterial catalysts (biocathodes), can satisfy these demands and have gained considerable attention in recent years. Achievements with biocathodes over the past 3-4. years have been particularly impressive not only with respect to the biological aspects but also the system-wide considerations related to electrode materials and solution chemistry. The versatility of biocathodes enables us to use not only oxygen but also contaminants as possible electron acceptors, allowing nutrient removal and bioremediation in conjunction with electricity generation. Moreover, biocathodes create opportunities to convert electrical current into microbially generated reduced products. While many new experimental results with biocathodes have been reported, we are still in the infancy of their engineering development. This review highlights the opportunities, limits, and challenges of biocathodes. © 2010 Elsevier Ltd.

  14. Electron and Hole Transport Layers: Their Use in Inverted Bulk Heterojunction Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Sandro Lattante

    2014-03-01

    Full Text Available Bulk heterojunction polymer solar cells (BHJ PSCs are very promising organic-based devices for low-cost solar energy conversion, compatible with roll-to-roll or general printing methods for mass production. Nevertheless, to date, many issues should still be addressed, one of these being the poor stability in ambient conditions. One elegant way to overcome such an issue is the so-called “inverted” BHJ PSC, a device geometry in which the charge collection is reverted in comparison with the standard geometry device, i.e., the electrons are collected by the bottom electrode and the holes by the top electrode (in contact with air. This reverted geometry allows one to use a high work function top metal electrode, like silver or gold (thus avoiding its fast oxidation and degradation, and eliminates the need of a polymeric hole transport layer, typically of an acidic nature, on top of the transparent metal oxide bottom electrode. Moreover, this geometry is fully compatible with standard roll-to-roll manufacturing in air and is less demanding for a good post-production encapsulation process. To date, the external power conversion efficiencies of the inverted devices are generally comparable to their standard analogues, once both the electron transport layer and the hole transport layer are fully optimized for the particular device. Here, the most recent results on this particular optimization process will be reviewed, and a general outlook regarding the inverted BHJ PSC will be depicted.

  15. Energy and Electron Transfer Cascade in Self-Assembled Bilayer Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Ogunsolu, Omotola Olukemi; Murphy, Ian A; Wang, Jamie C; Das, Anjan; Hanson, Kenneth

    2016-10-04

    Current high efficiency dye-sensitized solar cells (DSSCs) rely on the incorporation of multiple chromophores, via either co-deposition or pre-formed assemblies, as a means of increasing broad band light absorption. These strategies have some inherent limitations including decreased total light absorption by each of the dyes, low surface loadings, and complex synthetic procedures. In this report, we introduce an alternative strategy, self-assembled bilayers, as a simple, step-wise method of incorporating two complementary chromophores into a DSSC. The bilayer devices exhibit a 10% increase in Jsc, Voc and η over the monolayer devices due to increased incident photon-to-electron conversion efficiency across the entire visible spectrum and slowed recombination losses at the interface. Directional energy and electron transfer towards the metal oxide surface are key steps in the bilayer photon-to-current generation process. These results are important as they open the door to a new architecture for harnessing broad band light in dye-sensitized devices.

  16. Percolation Theory in Solid Oxide Fuel Cell Composite Electrodes with a Mixed Electronic and Ionic Conductor

    Directory of Open Access Journals (Sweden)

    Meng Ni

    2013-03-01

    Full Text Available Percolation theory is generalized to predict the effective properties of specific solid oxide fuel cell composite electrodes, which consist of a pure ion conducting material (e.g., YSZ or GDC and a mixed electron and ion conducting material (e.g., LSCF, LSCM or CeO2. The investigated properties include the probabilities of an LSCF particle belonging to the electron and ion conducting paths, percolated three-phase-boundary electrochemical reaction sites, which are based on different assumptions, the exposed LSCF surface electrochemical reaction sites and the revised expressions for the inter-particle ionic conductivities among LSCF and YSZ materials. The effects of the microstructure parameters, such as the volume fraction of the LSCF material, the particle size distributions of both the LSCF and YSZ materials (i.e., the mean particle radii and the non-dimensional standard deviations, which represent the particle size distributions and the porosity are studied. Finally, all of the calculated results are presented in non-dimensional forms to provide generality for practical application. Based on these results, the relevant properties can be easily evaluated, and the microstructure parameters and intrinsic properties of each material are specified.

  17. Indium-Free Perovskite Solar Cells Enabled by Impermeable Tin-Oxide Electron Extraction Layers.

    Science.gov (United States)

    Hu, Ting; Becker, Tim; Pourdavoud, Neda; Zhao, Jie; Brinkmann, Kai Oliver; Heiderhoff, Ralf; Gahlmann, Tobias; Huang, Zengqi; Olthof, Selina; Meerholz, Klaus; Többens, Daniel; Cheng, Baochang; Chen, Yiwang; Riedl, Thomas

    2017-07-01

    Corrosive precursors used for the preparation of organic-inorganic hybrid perovskite photoactive layers prevent the application of ultrathin metal layers as semitransparent bottom electrodes in perovskite solar cells (PVSCs). This study introduces tin-oxide (SnOx ) grown by atomic layer deposition (ALD), whose outstanding permeation barrier properties enable the design of an indium-tin-oxide (ITO)-free semitransparent bottom electrode (SnOx /Ag or Cu/SnOx ), in which the metal is efficiently protected against corrosion. Simultaneously, SnOx functions as an electron extraction layer. We unravel the spontaneous formation of a PbI2 interfacial layer between SnOx and the CH3 NH3 PbI3 perovskite. An interface dipole between SnOx and this PbI2 layer is found, which depends on the oxidant (water, ozone, or oxygen plasma) used for the ALD growth of SnOx . An electron extraction barrier between perovskite and PbI2 is identified, which is the lowest in devices based on SnOx grown with ozone. The resulting PVSCs are hysteresis-free with a stable power conversion efficiency (PCE) of 15.3% and a remarkably high open circuit voltage of 1.17 V. The ITO-free analogues still achieve a high PCE of 11%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Relativistic magnetic reconnection in collisionless ion-electron plasmas explored with particle-in-cell simulations

    CERN Document Server

    Melzani, Mickaël; Folini, Doris; Winisdoerffer, Christophe; Favre, Jean M

    2014-01-01

    Magnetic reconnection is a leading mechanism for magnetic energy conversion and high-energy non-thermal particle production in a variety of high-energy astrophysical objects, including ones with relativistic ion-electron plasmas (e.g., microquasars or AGNs) - a regime where first principle studies are scarce. We present 2D particle-in-cell (PIC) simulations of low $\\beta$ ion-electron plasmas under relativistic conditions, i.e., with inflow magnetic energy exceeding the plasma rest-mass energy. We identify outstanding properties: (i) For relativistic inflow magnetizations (here