Electro-exfoliating graphene from graphite for direct fabrication of supercapacitor

A facile production of graphene via electro-exfoliation is demonstrated using different types of oxidizing agent (HNO3, NaNO3, H2SO4 and H2O2) in the presence of sodium dodecylbenzenesulfonate as a surfactant. Different types of surfactant–oxidizing agent solutions in different concentrations significantly influenced the electrochemical exfoliation of graphite rod. The surface morphology, layer thickness and defects of the as-produced graphene are further evaluated. Additionally, the as-produced graphene is fabricated as a supercapacitor electrode via direct vacuum filtration. Nylon membrane and polymer gel, each containing 2.0 M of potassium hydroxide, are utilized to investigate the influence of the electrolyte type on the capacitance performance. Upon 1000 charge/discharge cycles, the nylon membrane electrolyte recorded capacitance retention of 94%, whereas the polymer gel electrolyte recorded an impressive capacitance retention that exceeded 100%. The potential of the fabricated supercapacitor for real applications is manifested by its ability to light up a light-emitting diode upon charging

Enhanced enforcement of the foreign corrupt practices act: Improving the ethics of U.S. business practices abroad

Empirical research demonstrates that bribery has a detrimental impact on investment, economic growth, trade, and democratic governments. In response to rising bribery activity and the additional burdens placed on corporate officials by the Sarbanes-Oxley Act of 2002, enforcement of the Foreign Corrupt Practices Act (FCPA) of 1977 has reached an all-time high. Although many managers, financial officers, entrepreneurs, and auditors are aware of the FCPA\u27s objectives and mandates, many do not do an adequate job of protecting their firms, employees, and/or clients from fines and prison sentences. The purposes of this paper are to (1) analyze and describe bribery and FCPA case filings, sanctions, payments (bribes), and value of business to be obtained; (2) describe and analyze the important provisions of the FCPA; (3) discuss vicarious liability or the liability of U.S. firms and others for the acts of third parties; and (4) make recommendations to help firms improve their compliance with the FCPA. © 2012 by Emerald Group Publishing Limited

Prevalence and predictors of HIV-related stigma among institutional- and community-based caregivers of orphans and vulnerable children living in five less-wealthy countries

<p>Abstract</p> <p>Background</p> <p>In the face of the HIV/AIDS epidemic that has contributed to the dramatic increase in orphans and abandoned children (OAC) worldwide, caregiver attitudes about HIV, and HIV-related stigma, are two attributes that may affect caregiving. Little research has considered the relationship between caregiver attributes and caregiver-reported HIV-related stigma. In light of the paucity of this literature, this paper will describe HIV-related stigma among caregivers of OAC in five less wealthy nations.</p> <p>Methods</p> <p>Baseline data were collected between May 2006 through February 2008. The sample included 1,480 community-based and 192 institution-based caregivers. Characteristics of the community-based and institution-based caregivers are described using means and standard deviations for continuous variables or counts and percentages for categorical variables. We fit logistic regression models, both for the full sample and separately for community-based and institution-based caregivers, to explore predictors of acceptance of HIV.</p> <p>Results</p> <p>Approximately 80% of both community-based and institution-based caregivers were female; and 84% of institution-based caregivers, compared to 66% of community-based caregivers, said that they would be willing to care for a relative with HIV. Similar proportions were reported when caregivers were asked if they were willing to let their child play with an HIV-infected child. In a multivariable model predicting willingness to care for an HIV-infected relative, adjusted for site fixed effects, being an institution-based caregiver was associated with greater willingness (less stigma) than community-based caregivers. Decreased willingness was reported by older respondents, while willingness increased with greater formal education. In the adjusted models predicting willingness to allow one's child to play with an HIV-infected child, female gender and older age was associated with less willingness. However, willingness was positively associated with years of formal education.</p> <p>Conclusions</p> <p>The caregiver-child relationship is central to a child's development. OAC already face stigma as a result of their orphaned or abandoned status; the addition of HIV-related stigma represents a double burden for these children. Further research on the prevalence of HIV-related acceptance and stigma among caregivers and implications of such stigma for child development will be critical as the policy community responds to the global HIV/AIDS orphan crisis.</p

Gene expression profiling of rat spermatogonia and Sertoli cells reveals signaling pathways from stem cells to niche and testicular cancer cells to surrounding stroma

Background: Stem cells and their niches are studied in many systems, but mammalian germ stem cells (GSC) and their niches are still poorly understood. In rat testis, spermatogonia and undifferentiated Sertoli cells proliferate before puberty, but at puberty most spermatogonia enter spermatogenesis, and Sertoli cells differentiate to support this program. Thus, pre-pubertal spermatogonia might possess GSC potential and pre-pubertal Sertoli cells niche functions. We hypothesized that the different stem cell pools at pre-puberty and maturity provide a model for the identification of stem cell and niche-specific genes. We compared the transcript profiles of spermatogonia and Sertoli cells from pre-pubertal and pubertal rats and examined how these related to genes expressed in testicular cancers, which might originate from inappropriate communication between GSCs and Sertoli cells. Results: The pre-pubertal spermatogonia-specific gene set comprised known stem cell and spermatogonial stem cell (SSC) markers. Similarly, the pre-pubertal Sertoli cell-specific gene set comprised known niche gene transcripts. A large fraction of these specifically enriched transcripts encoded trans-membrane, extra-cellular, and secreted proteins highlighting stem cell to niche communication. Comparing selective gene sets established in this study with published gene expression data of testicular cancers and their stroma, we identified sets expressed genes shared between testicular tumors and pre-pubertal spermatogonia, and tumor stroma and pre-pubertal Sertoli cells with statistic significance. Conclusions: Our data suggest that SSC and their niche specifically express complementary factors for cell communication and that the same factors might be implicated in the communication between tumor cells and their micro-enviroment in testicular cancer

Chronic Obstructive Pulmonary Disease and Lung Cancer: Underlying Pathophysiology and New Therapeutic Modalities

Chronic obstructive pulmonary disease (COPD) and lung cancer are major lung diseases affecting millions worldwide. Both diseases have links to cigarette smoking and exert a considerable societal burden. People suffering from COPD are at higher risk of developing lung cancer than those without, and are more susceptible to poor outcomes after diagnosis and treatment. Lung cancer and COPD are closely associated, possibly sharing common traits such as an underlying genetic predisposition, epithelial and endothelial cell plasticity, dysfunctional inflammatory mechanisms including the deposition of excessive extracellular matrix, angiogenesis, susceptibility to DNA damage and cellular mutagenesis. In fact, COPD could be the driving factor for lung cancer, providing a conducive environment that propagates its evolution. In the early stages of smoking, body defences provide a combative immune/oxidative response and DNA repair mechanisms are likely to subdue these changes to a certain extent; however, in patients with COPD with lung cancer the consequences could be devastating, potentially contributing to slower postoperative recovery after lung resection and increased resistance to radiotherapy and chemotherapy. Vital to the development of new-targeted therapies is an in-depth understanding of various molecular mechanisms that are associated with both pathologies. In this comprehensive review, we provide a detailed overview of possible underlying factors that link COPD and lung cancer, and current therapeutic advances from both human and preclinical animal models that can effectively mitigate this unholy relationship

Approches pour une distribution de données à large échelle sur l'Internet

Dans cette thèse, nous étudions le problème de la distribution de contenu de grande taille sur Internet. Nous nous concentrons essentiellement sur deux services majeurs : la vidéo à la demande (VoD) et la réplication de fichiers (service de partage). Nous étudions en premier lieu comment fournir le service VoD à un grand nombre de clients dans un réseau dédié (par example Akamai). Nous proposons une nouvelle architecture très efficace à large échelle et développons un nouveau modèle analytique permettant le calcul du coût minimal pour transmettre la vidéo. Notre modèle analytique nous permet d'étude plusieurs scénarios intéressants comme le problème de dimensionnement d'un système VoD ou l'évaluation des choix architecturaux, tels que la transmission partielle de la vidéo par satellite. En second lieu, nous nous intéressons à la VoD dans un réseau pair-à-pair. Alors que la plupart des solutions actuelles utilise des arbres multicast pour transmettre la vidéo aux clients, nous montrons que nous pouvons atteindre une efficacité similaire et d'une façon plus simple en introduisant une nouvelle approche nommée PBA. Enfin, nous étudions la réplication des fichiers dans les réseaux pair-à-pair. Les solutions actuelles peuvent être classées en deux catégories, selon que les clients soient organisés en arbre ou en maille. Notre première contribution consiste à démontrer que les architectures en maille sont au moins aussi efficaces que celles en arbre, tout en restant plus simples et plus dynamiques. Nous élaborons ensuite une analyse complète des approches en maille en identifiant les principaux paramètres qui influent sur la performance du système.In this thesis, we address the problem of distributing large contents in the Internet. We focus on two interesting and very common services, video on demand (VoD) and file replication. We first investigate how to provide an efficient VoD service to a large number of clients in a dedicated overlay network (e.g. Akamai). Our contribution here is a new video distribution architecture that is highly scalable and very cost effective. The novelty of our architecture is an analytical cost model that allows us to find the minimum delivery cost of the video. Using the cost model, we study many interesting scenarios like the dimensioning problem of a VoD system from scratch or the evaluation of architectural choices. One architectural choice that we consider is the use of satellite to broadcast a part of the video. We then continue our work on VoD but in a P2P network (rather than overlay network). While previous work constructs multicast trees to deliver the video to clients, we prove that we can achieve a similar efficiency in a simpler way. To this purpose, we introduce a new approach, called PBA, where clients perform locally an algorithm to find available servants from which they retrieve the video. Finally, we study the use of P2P networks for file replication. Existing solutions for this service can be largely classified into tree-based and mesh-based approaches. Our first contribution here is to prove that mesh approaches can be at least as efficient as tree ones. Our second contribution is a complete analysis of mesh approaches where we identify the main parameters that that influence their performance.NICE-BU Sciences (060882101) / SudocSudocFranceF