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1.
medRxiv ; 2023 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-37808671

RESUMEN

Background: The impact of migration on HIV risk among non-migrating household members is poorly understood. We measured HIV incidence among non-migrants living in households with and without migrants in Uganda. Methods: We used four survey rounds of data collected from July 2011-May 2018 from non-migrant participants aged 15-49 years in the Rakai Community Cohort Study, an open, population-based cohort. Non-migrants were individuals with no evidence of migration between surveys or at the prior survey. The primary exposure, household migration, was assessed using census data and defined as ≥1 household member migrating in or out of the house from another community between surveys (∼18 months). Incident HIV cases tested positive following a negative result at the preceding visit. Incidence rate ratios (IRR) with 95% confidence intervals were estimated using Poisson regression with generalized estimating equations and robust standard errors. Analyses were stratified by gender, migration into or out of the household, and the relationship between non-migrants and migrants (i.e., any household migration, spouse, child). Findings: Overall, 11,318 non-migrants (5,674 women) were followed for 37,320 person-years. 28% (6,059/21,370) of non-migrant person-visits had recent migration into or out of the household, and 240 HIV incident cases were identified in non-migrating household members. Overall, non-migrants in migrant households were not at greater risk of acquiring HIV. However, HIV incidence among men was significantly higher when the spouse had recently migrated in (adjIRR:2·12;95%CI:1·05-4·27) or out (adjIRR:4·01;95%CI:2·16-7·44) compared to men with no spousal migration. Women with in- and out-migrant spouses also had higher HIV incidence, but results were not statistically significant. Interpretation: HIV incidence is higher among non-migrating persons with migrant spouses, especially men. Targeted HIV testing and prevention interventions such as pre-exposure prophylaxis could be considered for those with migrant spouses. Funding: National Institutes of Health, US Centers for Disease Control and Prevention. Research in context: We searched PubMed for studies focused on HIV acquisition, prevalence or sexual behaviors among non-migrants who lived with migrants in sub-Saharan Africa (SSA) using search terms such as "HIV", "Emigration and Immigration", "family", "spouses", "household", "parents", and "children". Despite high levels of migration and an established association with HIV risk in SSA, there is limited data on the broader societal impacts of migration on HIV acquisition risk among non-migrant populations directly impacted by it.There has been only one published study that has previously evaluated impact of migration on HIV incidence among non-migrating persons in sub-Saharan Africa. This study, which exclusively assessed spousal migration, was conducted in Tanzania more than two decades earlier prior to HIV treatment availability and found that non-migrant men with long-term mobile partners were more than four times as likely to acquire HIV compared to men who had partners that were residents. To the best of our knowledge, this is the first study to examine the effect of non-spousal migration, including any household migration and child migration, on HIV incidence among non-migrants. Added value of this study: In this study, we used data from the Rakai Community Cohort Study (RCCS), a population-based HIV surveillance cohort to measure the impact of migration on HIV incidence for non-migrant household members. The RCCS captures HIV incident events through regular, repeat HIV testing of participants and migration events through household censuses. Our study adds to the current literature by examining the general effect of migration in the household on HIV incidence in addition to child, and spousal migration. Using data from over 11,000 non-migrant individuals, we found that spousal, but not other types of household migration, substantially increased HIV risk among non-migrants, especially among men. Taken together, our results suggest that spousal migration may be associated with an increased risk of HIV acquisition in the period surrounding and immediately after spousal migration. Implications of all the available evidence: Our findings suggest that spousal migration in or out of the household is associated with greater HIV incidence. Targeted HIV testing and prevention interventions such as pre-exposure prophylaxis could be considered for men with migrant spouses.

2.
Int J Tuberc Lung Dis ; 23(9): 980-988, 2019 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-31615604

RESUMEN

BACKGROUND: Achieving the 90-90-90 targets for tuberculosis (TB) will require interventions that enhance diagnosis, linkage, treatment and adherence to care. As a first step in the process, our team designed a suite of smartphone applications known as miLINC to improve time from diagnosis to treatment initiation in drug-resistant TB patients.SETTING: Three clinical locations in a large, peri-urban district in KwaZulu-Natal, South Africa.OBJECTIVE: To assess the acceptability, feasibility and impact of the miLINC mobile health applications as a solution to reducing the time from presentation to treatment initiation of rifampicin-resistant (RR) TB patients.METHODS: We used a prospective, observational quality improvement evaluation of miLINC's impact among newly diagnosed patients with RR-TB.RESULTS: A convenience sample comprising details of 6341 patients with presumptive TB were entered into miLINC. Of the 631 TB-positive sputum specimens, 41 (6.5%) were found to be RR-TB. The mean time from clinical presentation to RR-TB treatment initiation was 3 days, 21 h, 17 min.CONCLUSION: This is the first study to suggest that the time from presentation to diagnosis and to treatment initiation for patients with RR-TB can be significantly improved using an integrated approach combining technology with appropriate human resources.


Asunto(s)
Antituberculosos/administración & dosificación , Aplicaciones Móviles , Teléfono Inteligente , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/efectos de los fármacos , Mycobacterium tuberculosis/aislamiento & purificación , Estudios Prospectivos , Rifampin/administración & dosificación , Sudáfrica , Tiempo de Tratamiento , Tuberculosis Resistente a Múltiples Medicamentos/diagnóstico , Adulto Joven
3.
Intern Med J ; 45(10): 1037-43, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26178306

RESUMEN

BACKGROUND: Carbapenems are traditionally reserved as the last line of defence for treatment of serious infections with multiresistant Gram-negative bacilli. Reports of Klebsiella pneumoniae carbapenemase (KPC)-producing organisms have been emerging globally, but rare in Australasia to date. We describe an outbreak of KPC-2 producing K. pneumoniae at an Australian hospital. METHODS: After initial detection in October 2012, a retrospective review of patients with meropenem-resistant K. pneumoniae to June 2012, and ongoing prospective surveillance, was undertaken. Included patients were admitted to the hospital after June 2012 and had meropenem-resistant K. pneumoniae isolated from any site. Available isolates underwent detection of the KPC-2 gene by polymerase chain reaction and molecular typing was performed to determine genetic relatedness between isolates. Point-prevalence screening was performed on selected wards to detect asymptomatic carriage. Infection control procedures were implemented to contain the outbreak. RESULTS: Ten cases were identified in the initial cluster. Eight were localised to a single inpatient ward. Point-prevalence screening revealed one extra case. After temporary containment, re-emergence of KPC-producing isolates was observed post October 2013 with 18 further cases identified. Four K. pneumoniae isolates in the 2012 cluster and 16 from the 2013-2014 cluster were referred for further testing. All carried the KPC-2 beta-lactamase gene. The 2012 isolates were genetically similar to the 2014 isolates. CONCLUSION: KPC-2 mediated resistance is an emerging threat in Australia. The re-emergence of KPC despite initial containment emphasises the need for constant vigilance in the microbiology laboratory and ongoing maintenance of infection control and antimicrobial stewardship activity.


Asunto(s)
Infección Hospitalaria/tratamiento farmacológico , Mortalidad Hospitalaria , Infecciones por Klebsiella/tratamiento farmacológico , Klebsiella pneumoniae/aislamiento & purificación , Resistencia betalactámica/genética , beta-Lactamasas/genética , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/uso terapéutico , Australia/epidemiología , Carbapenémicos/uso terapéutico , Brotes de Enfermedades , Femenino , Humanos , Control de Infecciones , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Estudios Retrospectivos , Adulto Joven
5.
Proc Biol Sci ; 280(1764): 20130502, 2013 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-23782876

RESUMEN

Neutral and niche theories give contrasting explanations for the maintenance of tropical tree species diversity. Both have some empirical support, but methods to disentangle their effects have not yet been developed. We applied a statistical measure of spatial structure to data from 14 large tropical forest plots to test a prediction of niche theory that is incompatible with neutral theory: that species in heterogeneous environments should separate out in space according to their niche preferences. We chose plots across a range of topographic heterogeneity, and tested whether pairwise spatial associations among species were more variable in more heterogeneous sites. We found strong support for this prediction, based on a strong positive relationship between variance in the spatial structure of species pairs and topographic heterogeneity across sites. We interpret this pattern as evidence of pervasive niche differentiation, which increases in importance with increasing environmental heterogeneity.


Asunto(s)
Ecosistema , Modelos Teóricos , Árboles/fisiología , Agricultura Forestal , Clima Tropical
6.
Nano Lett ; 13(6): 2553-7, 2013 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-23679003

RESUMEN

In specific solid-state materials, under the right conditions, collections of magnetic dipoles are known to spontaneously form into a variety of rather complex geometrical patterns, exemplified by vortex and skyrmion structures. While theoretically, similar patterns should be expected to form from electrical dipoles, they have not been clearly observed to date: the need for continued experimental exploration is therefore clear. In this Letter we report the discovery of a rather complex domain arrangement that has spontaneously formed along the edges of a thin single crystal ferroelectric sheet, due to surface-related depolarizing fields. Polarization patterns are such that nanoscale "flux-closure" loops are nested within a larger mesoscale flux closure object. Despite the orders of magnitude differences in size, the geometric forms of the dual-scale flux closure entities are rather similar.

7.
J Phys Condens Matter ; 24(2): 024204, 2012 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-22172983

RESUMEN

As part of an ongoing programme to evaluate the extent to which external morphology alters domain wall mobility in ferroelectrics, the electrical switching characteristics of single-crystal BaTiO(3) nanorods and thin film plates have been measured and compared. It was found that ferroelectric nanorods were more readily switched than thin plates; increasing the shape constraint therefore appears to enhance switchability. This observation is broadly consistent with previous work, in which local notches patterned along the length of nanorods enhanced switching (McMillen et al 2010 Appl. Phys. Lett. 96 042904), while antinotches had the opposite effect (McQuaid et al 2010 Nano Lett. 10 3566). In this prior work, local enhancement and denudation of the electric field was expected at the notch and antinotch sites, respectively, and this was thought to be the reason for the differences in switching behaviour observed. However, for the simple nanorods and plates investigated here, no differences in the electric field distributions are expected. To rationalise the functional measurements, domain development during switching was imaged directly by piezoresponse force microscopy. A two-stage process was identified, in which narrow needle-like reverse domains initially form across the entire interelectrode gap and then subsequently coarsen through domain wall propagation perpendicular to the applied electric field. To be consistent with the electrical switching data, we suggest that the initial formation of needle domains occurs more readily in the nanorods than in the plates.

8.
IET Nanobiotechnol ; 5(2): 52, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21495781

RESUMEN

In this study, the authors demonstrate the synthesis of various gold nanostructures through a one-step, green and complete bio-modulation approach. Nanoparticles were successfully synthesised by the addition of gold aqueous solution to fruit extracts, including orange, papaya, peach or lemon. The particles were of various shapes and sizes with high abundance, such as sphere, marigold, triangle and hexagon. The biocompatibility of the presented gold nanostructures was examined; haemolysis tests revealed a non-toxicity result in blood cell uptake of such gold nanostructures. This study opens the exciting possibility of synthesising various multi-shaped nanoparticles through a simple and green approach, as well as paving the way for future bio-applications.


Asunto(s)
Frutas/química , Compuestos de Oro/síntesis química , Nanopartículas del Metal/química , Extractos Vegetales/química , Carica , Cloruros , Citrus , Eritrocitos/química , Eritrocitos/efectos de los fármacos , Compuestos de Oro/química , Compuestos de Oro/farmacología , Hemólisis/efectos de los fármacos , Humanos , Nanopartículas del Metal/ultraestructura , Microscopía Electrónica de Transmisión , Tamaño de la Partícula , Prunus , Espectroscopía Infrarroja por Transformada de Fourier
9.
Nano Lett ; 10(9): 3566-71, 2010 Sep 08.
Artículo en Inglés | MEDLINE | ID: mdl-20715806

RESUMEN

Changes in domain wall mobility, caused by the presence of antinotches in single crystal BaTiO(3) nanowires, have been investigated. While antinotches appeared to cause a slight broadening in the distribution of switching events, observed as a function of applied electric field (inferred from capacitance-voltage measurements), the effect was often subtle. Greater clarity of information was obtained from Rayleigh analysis of the capacitance variation with ac field amplitude. Here the magnitude of the domain wall mobility parameter (alpha) associated with irreversible wall movements was found to be reduced by the presence of antinotches--an effect which became more noticeable on heating toward the Curie temperature. The reduction in this domain wall mobility was contrasted with the noticeable enhancement found previously in ferroelectric wires with notches. Finite element modeling of the electric field, developed in the nanowires during switching, revealed regions of increased and decreased local field at the center of the notch and antinotch structures, respectively; the absolute magnitude of field enhancement in the notch centers was considerably greater than the field reduction in the center of the antinotches and this was commensurate with the manner in, and degree to, which domain wall mobility appeared to be affected. We therefore conclude that the main mechanism by which morphology alters the irreversible component of the domain wall mobility in ferroelectric wire structures is via the manner in which morphological variations alter the spatial distribution of the electric field.

10.
Glob Public Health ; 5(4): 395-412, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20155547

RESUMEN

Many guidelines, including those produced by the World Health Organisation (WHO), have failed to adhere to rigorous methodological standards. Operational examples of guideline development processes may provide important lessons learned to improve the rigour and quality of future guidelines. To this end, this paper describes the process of developing WHO guidelines on prevention and care interventions for adults and adolescents living with HIV. Using a pragmatic, structured, evidence-based approach, we created an organising committee, identified topics, conducted systematic reviews, identified experts and distributed evidence summaries. Subsequently, 55 global HIV experts drafted and anonymously submitted guideline statements at the beginning of a conference. During the conference, participants voted on statements using scales evaluating appropriateness of the statements, strength of recommendation and level of evidence. After review of voting results, open discussion, re-voting and refinement of statements, a draft version of the guidelines was completed. A post-conference writing team refined the guidelines based on pre-determined guideline writing principles and incorporated external comments into a final document. Successes and challenges of the guideline development process were identified and are used to highlight current issues and debates in developing guidelines with a focus on implications for future guideline development at WHO.


Asunto(s)
Guías como Asunto , Infecciones por VIH/terapia , Política de Salud , Organización Mundial de la Salud , Adolescente , Adulto , Medicina Basada en la Evidencia , Infecciones por VIH/prevención & control , Humanos , Estudios de Casos Organizacionales , Desarrollo de Programa/métodos
11.
Eur Respir J ; 35(3): 667-75, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19797125

RESUMEN

Cooking oil fumes (COF) are known to be associated with respiratory diseases and risk of lung cancer. Involvement of trans,trans-2,4-decadienal (tt-DDE), a major component in COF, is suspected. Male CD-1(R) (ICR) mice were intratracheally instilled with either 8 or 24 mg.kg(-1) tt-DDE weekly for 8 weeks. Total numbers and types of cells in bronchoalveolar lavage fluid (BALF), as well as pathological changes, and inflammatory gene modulations in the lung tissues were assessed. We demonstrated that the number of alveolar macrophages in the BALF was significantly increased in tt-DDE-exposed animals. Histologically, there was a dose-correlated increase in epithelial hyperplasia and granulomatous nodules at the bronchioloalveolar junctions (BAJ). Although both Clara and alveolar type II cells were present in the BAJ lesion, only Clara cells were actively proliferative. However, only alveolar type II cells were found in the BAJ granulomatous nodules. Enhanced accumulation of phosphorylated signal transducer and activator of transcription 3 (pSTAT3), a known pro-carcinogenic factor, was also detected in many alveolar type II cells at the BAJ lesions. As both BAJ hyperplasia and enhanced pSTAT3 accumulation are known risk factors associated with increased lung adenocarcinoma development, these findings suggest that tt-DDE may pose a risk in lung carcinogenesis.


Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Aldehídos/efectos adversos , Bronquiolos/efectos de los fármacos , Macrófagos Alveolares/efectos de los fármacos , Mucosa Respiratoria/efectos de los fármacos , Aldehídos/administración & dosificación , Animales , Bronquiolos/patología , Líquido del Lavado Bronquioalveolar , Grasas Insaturadas en la Dieta/administración & dosificación , Grasas Insaturadas en la Dieta/efectos adversos , Hiperplasia/inducido químicamente , Instilación de Medicamentos , Macrófagos Alveolares/patología , Masculino , Ratones , Ratones Endogámicos ICR , Estrés Oxidativo , Factor de Transcripción STAT3/efectos de los fármacos , Compuestos Orgánicos Volátiles
12.
J Nanosci Nanotechnol ; 8(6): 2979-82, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18681034

RESUMEN

The weak second harmonic light generating from carbon nanotubes are detected. The signal intensity closely related to the density of pi-bonds attributed to the defects in the rolled graphene sheets, which is stimulated to have anharmonic oscillation as strongly affected by the environment. The intensities of SHG are diminished in order of well-aligned multi-wall carbon nanotubes (MWCNTs), randomly-aligned MWCNTs, and then to single-wall CNTs.

13.
Osteoarthritis Cartilage ; 16(12): 1560-71, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18565769

RESUMEN

OBJECTIVE: To provide a more complete picture of the effect of interleukin-1 beta (IL-1beta) on adult human articular chondrocyte gene expression, in contrast to the candidate gene approach. DESIGN: Chondrocytes from human knee cartilage were cultured in medium containing IL-1beta. Changes in gene expression were analyzed by microarray and reverse transcriptase-polymerase chain reaction analysis. The ability of transforming growth factor beta-1 (TGF-beta1), fibroblast growth factor (FGF)-18, and bone morphogenetic protein 2 (BMP-2) to alter the effects of IL-1beta was analyzed. Computational analysis of the promoter regions of differentially expressed genes for transcription factor binding motifs was performed. RESULTS: IL-1beta-treated human chondrocytes showed significant increases in the expression of granulocyte colony stimulating factor-3, endothelial leukocyte adhesion molecule 1 and leukemia inhibitory factor as well as for a large group of chemokines that include CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL8, CCL2, CCL3, CCL4, CCL5, CCL8, CCL20, CCL3L1, CX3CL1 and the cytokine IL-6. As expected, the mRNA for matrix metalloproteinase (MMP)-13 and BMP-2 also increased while mRNA for the matrix genes COL2A1 and aggrecan was down-regulated. A subset of chemokines increased rapidly at very low levels of IL-1beta. The phenotype induced by IL-1beta was partially reversed by TGF-beta1, but not by BMP-2. In the presence of IL-1beta, FGF-18 increased expression of ADAMTS-4, aggrecan, BMP-2, COL2A1, CCL3, CCL4, CCL20, CXCL1, CXCL3, CXCL6, IL-1beta, IL-6, and IL-8 and decreased ADAMTS-5, MMP-13, CCL2, and CCL8. Computational analysis revealed a high likelihood that the most up-regulated chemokines are regulated by the transcription factors myocyte enhancer binding factor-3 (MEF-3), CCAAT/enhancer binding protein (C/EBP) and nuclear factor-kappa B (NF-kappaB). CONCLUSION: IL-1beta has a diverse effect on gene expression profile in human chondrocytes affecting matrix genes as well as chemokines and cytokines. TGF-beta1 has the ability to antagonize some of the phenotype induced by IL-1beta.


Asunto(s)
Artritis/metabolismo , Cartílago Articular/metabolismo , Condrocitos/metabolismo , Factores de Crecimiento de Fibroblastos/antagonistas & inhibidores , Interleucina-1beta/antagonistas & inhibidores , Factor de Crecimiento Transformador beta/antagonistas & inhibidores , Artritis/genética , Células Cultivadas , Quimiocinas/metabolismo , Quimiocinas/farmacología , Regulación de la Expresión Génica/genética , Humanos , Interleucina-1beta/farmacología , FN-kappa B/metabolismo , Factor de Crecimiento Transformador beta/farmacología , Regulación hacia Arriba
14.
Cochrane Database Syst Rev ; (3): CD004773, 2005 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-16034947

RESUMEN

BACKGROUND: Cryptococcal disease is an opportunistic infection that causes significant morbidity and mortality in adults with HIV. Primary prophylaxis with antifungal interventions may decrease cryptococcal disease incidence and associated mortality. OBJECTIVES: To assess the efficacy of antifungal interventions for the primary prevention of cryptococcal disease in adults with HIV. SEARCH STRATEGY: We searched the following databases: MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), ClinicalTrials.gov, Database of Abstracts of Reviews of Effectiveness (DARE), Latin American and Caribbean Literature on the Health Sciences (LILACS), and the Cochrane Controlled Trials Register (CCTR). We reviewed abstracts from the following relevant conferences: International AIDS Conference, International AIDS Society Conference on HIV Pathogenesis and Treatment, and Conference on Retroviruses and Opportunistic Infections. We searched reference lists for all primary and other pertinent articles identified. We attempted to contact experts in the field, particularly primary authors of included studies, to better ensure completeness of included studies. We also approached pharmaceutical companies for any available and relevant unpublished data. The time period searched was from 1980 to August 2004. We placed no language restrictions on the search. Key words used include: meningitis, cryptococcal, cryptococcus, cryptococcosis, acquired immunodeficiency syndrome, human immunodeficiency virus, prophylaxis, chemoprevention, antifungal agents, and the Cochrane screen for randomized controlled trials. SELECTION CRITERIA: Randomized controlled trials using antifungal interventions for the primary prevention of cryptococcal disease in adults with HIV were selected. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial eligibility and quality. Trial authors, experts, and pharmaceutical companies were contacted for additional and/or missing information. Data were abstracted by two reviewers. Data were pooled, where appropriate, to yield summary estimates. MAIN RESULTS: Five studies (N=1316) were identified. All study patients had CD4 cell counts <300 cells/microl, and the majority of patients had CD4 cell counts <150 cells/microl. When all five studies are analyzed as a single group (N=1316), the incidence of cryptococcal disease was decreased in those taking primary prophylaxis (RR 0.21, 95% CI 0.09, 0.46) compared to those taking placebo. However, there was no significant difference in overall mortality observed (RR 1.01, 95% CI 0.71, 1.44). When the three studies using itraconazole as the intervention were analyzed together (N=798), the incidence of cryptococcal disease was decreased in those taking itraconazole for primary prophylaxis (RR 0.12, 95% CI 0.03, 0.51) compared to those taking placebo; however, there was no significant difference in overall mortality (RR 1.12, 95% CI 0.70, 1.80). When the two studies using fluconazole as the intervention were analyzed together (N=518), the incidence of cryptococcal disease was decreased in those taking fluconazole for primary prophylaxis (RR 0.25, 95% CI 0.07, 0.87) compared to those taking placebo; however, there was no significant difference in overall mortality (RR 0.59, 95% CI 0.14, 2.62). AUTHORS' CONCLUSIONS: Antifungal primary prophylaxis with either itraconazole or fluconazole is effective in reducing the incidence of cryptococcal disease in adults with advanced HIV disease. However, neither of these interventions has a clear effect on overall mortality. Further research is needed to better understand these interventions and the populations in which they may be most effective.


Asunto(s)
Infecciones Oportunistas Relacionadas con el SIDA/prevención & control , Antifúngicos/uso terapéutico , Criptococosis/prevención & control , Adulto , Fluconazol/uso terapéutico , Humanos , Itraconazol/uso terapéutico , Meningitis Criptocócica/prevención & control , Ensayos Clínicos Controlados Aleatorios como Asunto
15.
J Nanosci Nanotechnol ; 5(11): 1887-92, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16433426

RESUMEN

A solo carbon nanotube (CNT) was successfully grown on nickel electrodes by a microwave plasma enhanced chemical vapor deposition (MPECVD) method equipped with an impedance-matched substrate holder with the reaction gases composed of hydrogen (H2), carbon dioxide (CO2), and methane (CH4) mixtures. An introduction of carbon dioxide gas before CNTs growth, the substrate temperature can easily be reached above 610 degrees C even heated at a low microwave power. This can be enunciated from fact that carbon dioxide inherits with higher bond energy for molecular dissociation, lower thermal conductivity, and higher heat capacity in comparing to other gases. The electron field emissions for randomly aligned CNTs and well-aligned CNTs grown by MPECVD and by radio frequency assisted hot-filament methods, respectively, are measured and compared. The higher field emission characteristic of the randomly aligned CNTs is presumed to be due to the protruded CNTs, which inheriting with less screening effect and manifesting with defects are crucial to play the effective emission sites.


Asunto(s)
Nanoestructuras/química , Nanotecnología/métodos , Nanotubos de Carbono/química , Dióxido de Carbono/química , Cristalización , Conductividad Eléctrica , Impedancia Eléctrica , Electroquímica , Electrodos , Gases , Calor , Hidrógeno/química , Ensayo de Materiales , Metano/química , Microscopía Electrónica de Rastreo , Microondas , Modelos Químicos , Nanotubos , Níquel/química , Temperatura
17.
Nature ; 417(6885): 139, 2002 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-12000951

RESUMEN

In the electrodeposition of metals, a widely used industrial technique, bubbles of gas generated near the cathode can adversely affect the quality of the metal coating. Here we use phase-contrast radiology with synchrotron radiation to witness directly and in real time the accumulation of zinc on hydrogen bubbles. This process explains the origin of the bubble-shaped defects that are common in electrodeposited coatings.

18.
Med Biol Eng Comput ; 40(1): 128-36, 2002 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11954700

RESUMEN

Pain control in conscious patients was investigated using a push-button, demand-driven supply of drugs. A fuzzy logic patient-controlled analgesia (PCA) algorithm was compared with a conventional algorithm, for alfentanil administration in extracorporeal shock-wave lithotripsy. The conventional PCA algorithm used an initial dose of 0.25mg, a fixed infusion rate of 60 mg h(-1) and a fixed bolus size of 0.2 mg with a 1 min lockout. The fuzzy logic PCA algorithm used an initial dose of 0.25 mg, a changeable infusion rate and a bolus size of 0.1 or 0.05 mg. The infusion rate was adjusted according to a look-up table that accepted the button-pressing history over the last three lockout intervals. The look-up table was designed using fuzzy logic. The bolus size was adjusted according to the button-pressing history over the past two lockout intervals. Twelve patients were treated using conventional PCA, and thirteen were treated with PCA + fuzzy logic control (FLC). PCA + FLC patients consumed 45% less drug. Also, PCA + FLC patients had a mean delivery/demand ratio of 82%, compared with 60% in conventional PCA. When the pain intensity scale was analysed, PCA + FLC patients had acceptable pain intensity at 62%, compared with 44% in conventional PCA.


Asunto(s)
Analgesia Controlada por el Paciente/métodos , Lógica Difusa , Cálculos Renales/terapia , Litotricia , Adulto , Anciano , Alfentanilo/administración & dosificación , Algoritmos , Analgésicos Opioides/administración & dosificación , Esquema de Medicación , Femenino , Humanos , Masculino , Persona de Mediana Edad
19.
Cell Mol Life Sci ; 59(11): 1972-82, 2002 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-12530527

RESUMEN

The cellular response and detoxification mechanisms in porcine endothelial cells (PAECs) to arsenic trioxide (As2O3), sodium arsenite (NaAsO2) and sodium arsenate (Na2HAsO4) were investigated. NaAsO2 at 20 microM for 72 h increased Cu/Zn superoxide dismutase activity resulting in elevated intracellular hydrogen peroxide levels, but As2O3 and Na2HAsO4 did not. Trivalent arsenic compounds increased intracellular oxidized glutathione (GSSG) and total glutathione (GSH) and cellular glutathione peroxidase (cGPX) and glutathione S-transferase (GST) activity, but not glutathione reductase activity. The increased cGPX activity resulted in an elevated cellular GSSG content. Na2HAsO4 increased the cellular GSSG level at 72 h compared to controls. These results imply that the increased GSH content responding to the oxidative stress by trivalent arsenic compounds may be mainly related to the regulation of GSH turnover. The increased GST activity implies that the elevated intracellular GSH level responding to the oxidative stress may be used to conjugate arsenic in PAECs and facilitate arsenic efflux.


Asunto(s)
Antioxidantes/metabolismo , Arsenicales/farmacología , Glutatión/metabolismo , Reactivos de Sulfhidrilo/farmacología , Animales , Aorta Torácica/efectos de los fármacos , Aorta Torácica/metabolismo , Arsénico/metabolismo , Western Blotting , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Disulfuro de Glutatión/efectos de los fármacos , Peróxido de Hidrógeno/metabolismo , Oxidación-Reducción/efectos de los fármacos , Superóxido Dismutasa/efectos de los fármacos , Porcinos
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