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1.
Pediatr Nephrol ; 35(4): 677-685, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31845058

RESUMEN

BACKGROUND: Data on long-term outcomes in children who have received renal replacement therapy (RRT) for end-stage renal disease are limited. METHODS: We studied long-term survival and incidence of fatal and nonfatal cardiovascular disease (CVD) events and determinants of these outcomes in children who initiated RRT between 1961 and 2013 using data from the Scottish Renal Registry (SRR). Linkage to morbidity records was available from 1981. RESULTS: A total of 477 children of whom 55% were boys, almost 50% had congenital urinary tract disease (CAKUT), 10% received a transplant as the first mode of RRT and almost 60% were over 11 years of age at start of RRT were followed for a median of 17.8 years (interquartile range (IQR) 8.7-26.6 years). Survival was 87.3% (95% confidence interval (CI) 84.0-90.1) at 10 years and 77.6% (95% CI 73.3-81.7) at 20 years. During a median follow-up of 14.96 years (IQR 7.1-22.9), 20.9% of the 381 patients with morbidity data available had an incident of CVD event. Age < 2 years at start of RRT, receiving dialysis rather than a kidney transplant and primary renal disease (PRD) other than CAKUT or glomerulonephritis (GN), were associated with a higher risk of all-cause mortality. Male sex, receiving dialysis rather than a kidney transplant and PRD other than CAKUT or GN, was associated with a higher risk of CVD incidence. CONCLUSIONS: Mortality and CVD incidence among children receiving RRT are high. PRD and RRT modality were associated with increased risk of both all-cause mortality and CVD incidence.


Asunto(s)
Enfermedades Cardiovasculares/mortalidad , Fallo Renal Crónico/mortalidad , Diálisis Renal/efectos adversos , Adolescente , Enfermedades Cardiovasculares/etiología , Niño , Preescolar , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Fallo Renal Crónico/terapia , Trasplante de Riñón/mortalidad , Estudios Longitudinales , Masculino , Sistema de Registros , Diálisis Renal/estadística & datos numéricos , Escocia/epidemiología
2.
Environ Sci Technol ; 52(5): 2735-2741, 2018 03 06.
Artículo en Inglés | MEDLINE | ID: mdl-29400458

RESUMEN

Predicting the transport of contaminants in porous media is crucial to protecting public health and remediating contaminated soil and groundwater. However, the prediction of contaminant transport is challenging due to the presence of mobile and immobile colloids. The work performed in this experimental investigation quantified the role of immobile clay colloids on metal transport through sets of column breakthrough experiments under varying solution chemistry, clay content, and flow rate. Georgia kaolinite was chosen as the colloidal material, and Pb(II) was chosen as the dissolved contaminant. The silica sand used as the bed material was sized to ensure that the kaolinite colloids remained stationary during the column experiments. Results indicated that retardation of the Pb(II) breakthrough curve was observed as ionic strength decreased and kaolinite content and pH increased, while no significant variation of Pb(II) breakthrough was observed at any kaolinite content as flow rate decreased. This work demonstrated that, in the presence of immobile kaolinite colloids, Pb(II) breakthrough curves strongly depended on the pH and ionic strength, which controlled the charge on the surface functional groups and the surface availability of metal adsorption sites on immobile kaolinite colloids. In addition, the evaluation of unknown first-order coefficients in the continuum governing equation, bed efficiency, and Pb(II) saturation provided a quantitative description of Pb(II) breakthrough curves.


Asunto(s)
Caolín , Metales Pesados , Adsorción , Coloides , Georgia
3.
Chemosphere ; 355: 141758, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38518922

RESUMEN

The unsaturated behavior of permeable reactive barriers (PRB) is a critical component in predicting the removal efficiency through the adsorption of contaminants. This study investigates the framework to estimate the soil water characteristic curve (SWCC) and hydraulic conductivity function (HCF) for iron oxide-coated sand (IOCS) and zeolite, which are common materials used in PRBs. A multistep outflow (MSO) experiment was performed and the results of the MSO experiment were used to optimize associated parameters in Kosugi's SWCC and HCF. In addition, three scenarios of optimization analysis were investigated to evaluate the best-fitting model for estimating SWCC and HCF. The low root mean square error (RMSE) of fitted parameters indicates the Kosugi model well described the observed suction profiles in MSO experiments. In addition, the lowest RMSE and coefficient of variation suggested the inclusion of the additional parameter ß provided the best estimation of the three materials (clean sand, IOCS, and zeolite). The physically reasonable estimation of SWCC and HCF of the three materials from the optimized parameters suggests the proposed framework is a reasonable model for the unsaturated behavior of PRBs.


Asunto(s)
Compuestos Férricos , Contaminantes Químicos del Agua , Zeolitas , Agua , Suelo , Arena , Contaminantes Químicos del Agua/análisis
4.
Epidemiology ; 24(6): 845-53, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24045718

RESUMEN

BACKGROUND: Studies of health risks associated with recreational water exposure require investigators to make choices about water quality indicator averaging techniques, exposure definitions, follow-up periods, and model specifications; however, investigators seldom describe the impact of these choices on reported results. Our objectives are to report illness risk from swimming at a marine beach affected by nonpoint sources of urban runoff, measure associations between fecal indicator bacteria levels and subsequent illness among swimmers, and investigate the sensitivity of results to a range of exposure and outcome definitions. METHODS: In 2009, we enrolled 5674 people in a prospective cohort at Malibu Beach, a coastal marine beach in California, and measured daily health symptoms 10-19 days later. Concurrent water quality samples were analyzed for indicator bacteria using culture and molecular methods. We compared illness risk between nonswimmers and swimmers, and among swimmers exposed to various levels of fecal indicator bacteria. RESULTS: Diarrhea was more common among swimmers than nonswimmers (adjusted odds ratio = 1.88 [95% confidence interval = 1.09-3.24]) within 3 days of the beach visit. Water quality was generally good (fecal indicator bacteria levels exceeded water quality guidelines for only 7% of study samples). Fecal indicator bacteria levels were not consistently associated with swimmer illness. Sensitivity analyses demonstrated that overall inference was not substantially affected by the choice of exposure and outcome definitions. CONCLUSIONS: This study suggests that the 3 days following a beach visit may be the most relevant period for health outcome measurement in recreational water studies. Under the water quality conditions observed in this study, fecal indicator bacteria levels were not associated with swimmer illness.


Asunto(s)
Playas , Diarrea/etiología , Exposición a Riesgos Ambientales/efectos adversos , Natación , Microbiología del Agua/normas , Calidad del Agua/normas , Adolescente , Adulto , California/epidemiología , Niño , Preescolar , Diarrea/epidemiología , Femenino , Estudios de Seguimiento , Humanos , Lactante , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Recreación , Riesgo , Factores de Tiempo , Adulto Joven
5.
Environ Sci Technol ; 47(6): 2769-76, 2013 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-23413980

RESUMEN

Organoclays are highly sorptive engineered materials that can be used as amendments in barrier systems or geosynthetic liners. The performance of confining and isolating the nonpolar organic contaminants by those barrier/lining systems is essentially controlled by the process of organic contaminant mass transport in nanopores of organoclays. In this article, we use molecular dynamics (MD) simulations to study the sorption and diffusion of organic sorbates in interlayers of sodium montmorillonite and hexadecyltrimethylammonium (HDTMA(+))-modified montmorillonite clays. Simulated system consisted of the clay framework, interlayer organic cation, water, and organic sorbate. Their interactions were addressed by the combined force field of ClayFF, constant-valence force field, and SPC water model. Simulation results indicated that in HDTMA coated clay nanopores, diffusion of nonpolar species benzene was slowed because they were subjected to influence of both the pore wall and the HDTMA surfactant. This suggested the nonpolar organic compound diffusion in organophilic clays can be affected by molecular size of diffusive species, clay pore size, and organic surfactant loading. Additionally, a model that connected the diffusion rate of organic compounds in the bulk organoclay matrix with macropores and nanopores was established. The impact of intercalated organic cations on the diffusion dominated mass transport of organic compounds yielded insight into the prediction of the apparent diffusion behavior of organic compounds in organic-modified clays.


Asunto(s)
Silicatos de Aluminio/química , Bentonita/química , Simulación de Dinámica Molecular , Nanoporos/ultraestructura , Compuestos de Amonio Cuaternario/química , Adsorción , Arcilla , Difusión
6.
Langmuir ; 28(47): 16393-400, 2012 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-23126472

RESUMEN

This study uses molecular dynamics (MD) modeling to examine the interlayer microstructures of montmorillonite intercalated with single chain QACs. Three types of QACs-tetramethylammonium (TMA), decyltrimethylammonium (DTMA), and hexadecyltrimethylammonium (HDTMA)-were selected to synthesize the organoclay complex, and the surfactant arrangement was analyzed quantitatively in systems in the absence of water. A series of arrangement patterns of interlayer QAC surfactant were observed, including lateral monolayers, lateral bilayers, pseudotrilayers, and paraffin monolayers, in agreement with previous experimental results. The effects of increasing one carbon chain length and amount of loading of QAC on the resultant QAC arrangement are summarized, yielding a model that provides insight into the prediction of synthesized QAC-clay microstructure and engineering behavior in practice.

7.
Environ Sci Technol ; 46(7): 3999-4007, 2012 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-22364194

RESUMEN

Organoclays synthesized from single chain quaternary ammonium cations (QAC) ((CH(3))(3)NR(+)) exhibit different mechanisms for the sorption of nonpolar organic compounds as the length of the carbon chain is increased. The interaction between a nonpolar sorbate and an organoclay intercalated with small QACs has been demonstrated to be surface adsorption, while partitioning is the dominant mechanism in clays intercalated with long chain surfactants. This study presents the results of a molecular dynamics (MD) simulation performed to examine the sorption mechanisms of benzene in the interlayer of three organoclays with chain lengths ranging from 1 to 16 carbons: tetramethylammonium (TMA) clay; decyltrimethylammonium (DTMA) clay; and hexadecyltrimethylammonium (HDTMA) clay. The basis of the overall simulation was a combined force field of ClayFF and CVFF. In the simulations, organic cations were intercalated and benzene molecules were introduced to the interlayer, followed by whole system NPT and NVT time integration. Trajectories of all the species were recorded after the system reached equilibrium and subsequently analyzed. Simulation results confirmed that the arrangement of the surfactants controlled the sorption mechanism of organoclays. Benzene molecules were observed to interact directly with the clay surface in the presence of TMA cations, but tended to interact with the aliphatic chain of the HDTMA cation in the interlayer. The simulation provided insight into the nature of the adsorption/partitioning mechanisms in organoclays, and explained experimental observations of decreased versus increased uptake capacities as a function of increasing total organic carbon (TOC) for TMA clay and HDTMA clay, respectively. The transition of sorption mechanisms was also quantified with simulation of DTMA clay, with a chain length between that of TMA and HDTMA. Furthermore, this study suggested that at the molecular level, the controlling factor for the ultimate sorption capacity is available surface sites in the case of TMA clay, and density of aliphatic chains within the interlayer space for HDTMA clay.


Asunto(s)
Bentonita/química , Compuestos de Cetrimonio/química , Simulación de Dinámica Molecular , Compuestos de Amonio Cuaternario/química , Adsorción , Silicatos de Aluminio/química , Benceno/química , Cationes , Arcilla , Difusión , Tensoactivos/química , Termodinámica
8.
J Environ Manage ; 113: 128-36, 2012 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-23017584

RESUMEN

A laboratory-scale study was conducted to assess the feasibility of the production of fired bricks from sediments dredged from the Savannah Harbor (Savannah, GA, USA). The dredged sediment was used as the sole raw material, or as a 50% replacement for natural brick-making clay. Sediment bricks were prepared using the stiff mud extrusion process from raw mixes consisted of 100% dredged sediment, or 50% dredged sediment and 50% brick clay. The bricks were fired at temperatures between 900 and 1000 °C. Physical and mechanical properties of the dredged sediment brick were found to generally comply with ASTM criteria for building brick. Water absorption of the dredged sediment bricks was in compliance with the criteria for brick graded for severe (SW) or moderate (MW) weathering. Compressive strength of 100% dredged sediment bricks ranged from 8.3 to 11.7 MPa; the bricks sintered at 1000 °C met the requirements for negligible weathering (NW) building brick. Mixing the dredged sediment with natural clay resulted in an increase of the compressive strength. The compressive strength of the sediment-clay bricks fired at 1000 °C was 29.4 MPa, thus meeting the ASTM requirements for the SW grade building brick. Results of this study demonstrate that production of fired bricks is a promising and achievable productive reuse alternative for Savannah Harbor dredged sediments.


Asunto(s)
Materiales de Construcción , Sedimentos Geológicos , Silicatos de Aluminio , Arcilla , Fuerza Compresiva , Conservación de los Recursos Naturales , Georgia , Ríos
9.
J Patient Saf ; 17(1): 30-35, 2021 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-27811588

RESUMEN

BACKGROUND: Although attention to patient safety issues in the home care setting is growing, few studies have highlighted health system-level concerns that contribute to patient safety incidents in the home. Found-on-floor (FOF) incidents are a key patient safety issue that is unique to the home care setting and highlights a number of opportunities for system-level improvements to drive enhanced patient safety. METHODS: We completed a multi-incident analysis of FOF incidents documented in the electronic record system of a home health care agency in Toronto, Canada, for the course of 1 year between January 2012 and February 2013. RESULTS: Length of stay (LOS) was identified as the cross-cutting theme, illustrating the following 3 key issues: (1) in the short LOS group, a lack of information continuity led to missed fall risk information by home care professionals; (2) in the medium LOS group, a lack of personal support worker/carer training in fall prevention led to inadequate fall prevention activity; and (3) in the long LOS group, a lack of accountability policy at a system level led to a lack of fall risk assessment follow-up. CONCLUSIONS: Our study suggests that considering LOS in the home care sector helps expose key system-level issues enabling safety incidents such as FOF to occur. Our multi-incident analysis identified a number of opportunities for system-level changes that might improve fall prevention practice and reduce the likelihood of FOF incidents in the home. Specifically, investment in electronic health records that are functional across the continuum of care, further research and understanding of the training and skills of personal support workers, and enhanced incentives or more punitive approaches (depending on the circumstances) to ensure accountability in home safety will strengthen the home care sector and help prevent FOF incidents among older people.


Asunto(s)
Accidentes por Caídas/estadística & datos numéricos , Seguridad del Paciente/normas , Anciano , Anciano de 80 o más Años , Canadá , Femenino , Humanos , Masculino
10.
Waste Manag ; 135: 122-129, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34492605

RESUMEN

Recently, sustainable energy portfolios have added biomass combustion and coal/biomass co-combustion as alternative fuel sources for generation of electricity. Fly ashes that result from combustion of biomass or its co-combustion with coal contain relatively high contents of unburned carbon, while increasingly stringent air quality regulations have also increased the residual carbon content in fly ash produced by coal combustion alone. While previous studies documented the mechanical and chemical behavior of fly ash relatively well, the thermal characteristics of those fly ashes have not been well studied. Therefore, this study evaluated the thermal conductivity of fly ashes with varied carbon and initial biomass contents to quantify the impact of unburned carbon particles and biomass-fired fly ash on thermal conductivity. Observed results demonstrated that the thermal conductivity of fly ashes almost linearly decreased as biomass content increased while the variation of thermal conductivity of fly ashes caused by unburned carbon content was relatively low. In addition, the thermal conductivity of fly ashes was lower than that of natural soils mainly because of the microporous structures of fly ash particles. The trend of thermal conductivity of fly ashes as a function of dry density was consistent with that of natural soils, due to the similar mineralogy of fly ash with that of natural soils. The developed stepwise regression model indicated that the porosity and the specific gravity was the most critical factor in predicting the thermal conductivity of fly ash.


Asunto(s)
Carbono , Ceniza del Carbón , Biomasa , Carbón Mineral/análisis , Ceniza del Carbón/análisis , Material Particulado/análisis , Conductividad Térmica
11.
J Hazard Mater ; 373: 476-482, 2019 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-30947037

RESUMEN

Cotransport of heavy metals, Pb, Cu and Zn (multi-metal system), and transport of those metals (single-metal system) were investigated by performing laboratory soil column experiment under the presence of kaolinite colloids. Preequilibrated kaolinite colloids with heavy metal solution was injected to the column until 10 pore volumes under two different flow rates and three different concentration of kaolinite colloids. Heavy metal concentration in effluent showed that the mobility of Pb was facilitated as kaolinite colloids concentration (Cc0) increases under high flow rate while the mobility of Pb and Cu were retarded as Cc0 increases under low flow rate. In addition, optimized first order rate coefficient related to sand-heavy metal interaction and estimated bed efficiency of experimental breakthrough curves demonstrated that the presence of mobile kaolinite colloids delayed the adsorption of heavy metals to the sand and facilitated the transport. Colloid associated contaminant transport model used in this study was found to be well fitted to the experimental breakthrough curves with the parameters associated with observed heavy metal transport without kaolinite colloids and adsorption/desorption between the heavy metals and the mobile kaolinite colloids.

12.
J Rural Health ; 24(1): 55-9, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18257871

RESUMEN

CONTEXT: The obesity epidemic threatens the present and future health of adolescents in the United States. Yet, health care providers lack specific training for pediatric obesity assessment and management. PURPOSE: This study examined the adherence of rural Georgia primary care practitioners to an overweight adolescent management protocol. The study also documented the prevalence of obesity-associated physiological and behavioral risk factors among overweight adolescent patients. METHODS: Ten rural clinics (58 providers) were recruited and received a 90-minute adolescent overweight assessment and management training session. Select biochemical, dietary, physical activity, and physical inactivity behaviors were assessed in overweight adolescent patients. Medical charts were abstracted to assess practitioner compliance with an overweight assessment protocol and patient adherence to a 16-week follow-up visit. FINDINGS: Providers were receptive to training and complied with the recommended protocol. Eighty-five overweight adolescents were assessed, but only 49 (57%) completed the scheduled 16-week follow-up visit. Physical, biochemical, and behavioral assessments revealed that 13%-27% of the participants had abnormal levels of lipids, fasting glucose, and glucose/insulin ratio, and 80.5% had waist circumferences above the 90th percentile. CONCLUSIONS: Practitioners complied with the assessment and follow-up protocol, leading to the discovery of previously unrecognized risk factors in many overweight adolescent patients. Lack of patient adherence to follow-up was the greatest limiting factor for obesity management. Further efforts are needed to implement and evaluate training to improve the management of adolescent overweight, especially in rural communities.


Asunto(s)
Personal de Salud/educación , Sobrepeso/prevención & control , Población Rural , Adolescente , Antropometría , Presión Sanguínea , Femenino , Georgia , Conductas Relacionadas con la Salud , Humanos , Masculino , Evaluación de Programas y Proyectos de Salud/métodos , Factores de Riesgo , Encuestas y Cuestionarios
13.
Malar J ; 6: 14, 2007 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-17274810

RESUMEN

BACKGROUND: Coverage of vulnerable groups with insecticide-treated nets (ITNs) in Ghana, as in the majority of countries of sub-Saharan Africa is currently low. A voucher scheme was introduced in Volta Region as a possible sustainable delivery system for increasing this coverage through scale-up to other regions. Successful scale-up of public health interventions depends upon optimal delivery processes but operational research for delivery processes in large-scale implementation has been inadequate. METHODS: A simple tool was developed to monitor numbers of vouchers given to each health facility, numbers issued to pregnant women by the health staff, and numbers redeemed by the distributors back to the management agent. Three rounds of interviews were undertaken with health facility staff, retailers and pregnant women who had attended antenatal clinic (ANC). RESULTS: During the one year pilot 25,926 vouchers were issued to eligible women from clinics, which equates to 50.7% of the 51,658 ANC registrants during this time period. Of the vouchers issued 66.7% were redeemed by distributors back to the management agent. Initially, non-issuing of vouchers to pregnant women was mainly due to eligibility criteria imposed by the midwives; later in the year it was due to decisions of the pregnant women, and supply constraints. These in turn were heavily influenced by factors external to the programme: current household ownership of nets, competing ITN delivery strategies, and competition for the limited number of ITNs available in the country from major urban areas of other regions. CONCLUSION: Both issuing and redemption of vouchers should be monitored as factors assumed to influence voucher redemption had an influence on issuing, and vice versa. More evidence is needed on how specific contextual factors influence the success of voucher schemes and other models of delivery of ITNs. Such an evidence base will facilitate optimal strategic decision making so that the delivery model with the best probability of success within a given context is implemented. Rigorous monitoring has an important role to play in the successful scaling-up of delivery of effective public health interventions.


Asunto(s)
Ropa de Cama y Ropa Blanca , Atención a la Salud , Insecticidas , Malaria/prevención & control , Complicaciones Parasitarias del Embarazo/prevención & control , Sector Privado , Sector Público , Animales , Ropa de Cama y Ropa Blanca/provisión & distribución , Atención a la Salud/métodos , Atención a la Salud/organización & administración , Atención a la Salud/estadística & datos numéricos , Femenino , Ghana , Instituciones de Salud , Personal de Salud , Humanos , Insecticidas/farmacología , Entrevistas como Asunto , Control de Mosquitos , Embarazo
14.
J Colloid Interface Sci ; 313(2): 405-13, 2007 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-17511998

RESUMEN

This work describes the role of quaternary alkylammonium amendment length on sorption mechanisms of modified bentonites for four nonionic organic compounds; benzene, carbon tetrachloride, TCE, and 1,2-DCB. Tetramethyl to tetrabutyl alkyl amendments were studied and an important mechanistic shift occurred at the propyl chain length for all four solutes studied. Three- and four-carbon-chain functional groups on the ammonium cation resulted in a linear, rather than a curvilinear isotherm. The uptake on tetrapropyl and tetrabutylammonium clays was noncompetitive in binary systems and showed negligible sensitivity to temperature variations, indicating the linear isotherms describe a partitioning uptake mechanism for these organoclays. The adsorptive organoclays (tetramethyl and tetraethylammonium clays) were fit with the Dubinin-Radushkevich equation to investigate the application of the Polanyi-Manes potential theory to organoclay adsorption. It was found that TCE and carbon tetrachloride, with similar physical and chemical characteristics, behaved according to the Polanyi-Manes theory. Benzene showed an anomalously high adsorption volume limit, possibly due to dense packing in the adsorption space or chemisorption to the short chain alkyl groups.

15.
Lab Med ; 46(2): 84-9; quiz e28-9, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25918186

RESUMEN

OBJECTIVE: To assess the false-positive and false-negative rates of a 4th-generation human immunodeficiency virus (HIV) assay, the Abbott ARCHITECT, vs 2 HIV 3rd-generation assays, the Siemens Centaur and the Ortho-Clinical Diagnostics Vitros. METHODS: We examined 123 patient specimens. In the first phase of the study, we compared 99 specimens that had a positive screening result via the 3rd-generation Vitros assay (10 positive, 82 negative, and 7 indeterminate via confirmatory immunofluorescent assay [IFA]/Western blot [WB] testing). In the second phase, we assessed 24 HIV-1 RNA-positive (positive result via the nuclear acid amplification test [NAAT] and negative/indeterminate results via the WB test) specimens harboring acute HIV infection. RESULTS: The 4th-generation ARCHITECT assay yielded fewer false-positive results (n = 2) than the 3rd-generation Centaur (n = 9; P = .02) and Vitros (n = 82; P <.001) assays. One confirmed positive case had a false-negative result via the Centaur assay. When specimens from the 24 patients with acute HIV-1 infection were tested, the ARCHITECT assay yielded fewer false-negative results (n = 5) than the Centaur (n = 10) (P = .13) and the other 3rd-generation tests (n = 16) (P = .002). CONCLUSIONS: This study indicates that the 4th-generation ARCHITECT HIV assay yields fewer false-positive and false-negative results than the 3rd-generation HIV assays we tested.


Asunto(s)
Pruebas Diagnósticas de Rutina/métodos , Anticuerpos Anti-VIH/sangre , Antígenos VIH/sangre , Infecciones por VIH/diagnóstico , VIH-1/inmunología , Reacciones Falso Positivas , Femenino , Humanos , Inmunoensayo/métodos , Masculino , Pruebas Serológicas/métodos
16.
J Colloid Interface Sci ; 266(2): 251-8, 2003 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-14527447

RESUMEN

Sorption of three nonionic organic solutes (benzene, trichloroethene, and 1,2-dichlorobenzene) to hexadecyltrimethylammonium bentonite (HDTMA bentonite) and benzyltriethylammonium bentonite (BTEA bentonite) was measured as a function of total organic-carbon content at quaternary ammonium cation loadings ranging from 30 to 100% of the clay's cation-exchange capacity. Sorption of all three solutes to HDTMA bentonite was linear and sorption of all three solutes by the HDTMA bentonite increased as the organic-carbon content of the clay increased. 1,2-Dichlorobenzene sorbed most strongly to HDTMA bentonite, followed by benzene and TCE. The stronger sorption of benzene to HDTMA bentonite compared to TCE was unexpected based on a partition mechanism of sorption and consideration of solute solubility. LogK(oc) values for all three solutes increased with organic-carbon content. This suggests that the increased organic-carbon content alone may not explain the observed increase in sorption capacity. Sorption of the three solutes to BTEA bentonite was nonlinear and solute sorption increased with decreasing organic-carbon content, with a peak in the magnitude of solute sorption occurring at an organic-carbon content corresponding to 50% of CEC. Below 50% of CEC, sorption of all three solutes to BTEA bentonite decreased with decreasing organic-carbon content. Surface area measurements indicate that the surface area of both organobentonites generally decreased with increasing organic-carbon content. Since nonionic organic solute sorption to BTEA bentonite occurs by adsorption, the reduced sorption is likely caused by the reduction in surface area corresponding to increased organic-cation loading.

17.
J Hazard Mater ; 96(1): 91-7, 2003 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-12475481

RESUMEN

We investigate the use of organobentonites as liners for underground gasoline storage tanks to reduce the risk of subsurface contamination. A series of permeability measurements were conducted on two types of organobentonites: benzyltriethylammonium-bentonite (BTEA-bentonite) and hexadecyltrimethylammonium-bentonite (HDTMA-bentonite). Both water and commercial unleaded gasoline were used as the permeant liquids. Results of these measurements indicate that the intrinsic permeability of the organobentonite decreases by one to two orders of magnitude when the permeant liquid is changed from water to gasoline. Results of batch sorption measurements reveal that benzene sorption to both organobentonites from water is greater than benzene sorption to conventional bentonite. The magnitude of benzene sorption is related to the loading of the organic quaternary ammonium cation on the clay. As the HDTMA cation loading increases from 25% of cation exchange capacity (CEC) to 120% of CEC, benzene sorption increases. However, as the BTEA cation loading increases from 40 to 120% of CEC, benzene sorption decreases. Collectively, these results suggest that organobentonites can be used effectively to reduce hydrocarbon migration rates beneath leaking underground gasoline storage tanks, and that the optimal organic cation loading with respect to pollutant sorption may be less than 50% of cation exchange capacity for some organobentonite-solute combinations.


Asunto(s)
Bentonita/química , Gasolina , Hidrocarburos/química , Contaminación del Agua/prevención & control , Adsorción , Permeabilidad
18.
AANA J ; 70(1): 53-6, 2002 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11887545

RESUMEN

The purpose of this study was to determine the amount of microbial growth that develops on the anesthesia machine after a full day's use in the operating room. This descriptive bacteriology study is relevant to anesthesia practice because of the proximity of the oropharynx and multiple body fluids to anesthesia equipment and the potential for cross-contamination to patients and staff. The Wilcoxon signed rank test was used to evaluate the change in colony-forming units (CFUs) before and after use of equipment. The resulting P value of 0.12 indicated that the observed CFU increase was not statistically significant at the .05 level. The study identified many organisms that survive on the anesthesia machine tabletop, namely, coagulase-negative Staphylococcus, Bacillus, alpha Streptococcus, Acinetobacter, Staphylococcus aureus, and gram-negative rods. Several were expected to be found; however, alpha Streptococcus, Acinetobacter, S aureus, and gram-negative rods are pathogenic organisms causing respiratory infections and bacteremia, especially in patients with compromised conditions. Terminal cleaning methods may have changed during the course of the study, thereby contributing to the volume of microbes present before use and distorting the change in the number of CFUs before and after use.


Asunto(s)
Anestesiología/instrumentación , Infección Hospitalaria/prevención & control , Contaminación de Equipos , Control de Infecciones , Acinetobacter/aislamiento & purificación , Humanos , Staphylococcus aureus/aislamiento & purificación , Streptococcus/aislamiento & purificación
19.
Water Res ; 59: 23-36, 2014 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-24776951

RESUMEN

Use of fecal indicator bacteria (FIB) for monitoring beach water quality is based on their co-occurrence with human pathogens, a relationship that can be dramatically altered by fate and transport processes after leaving the human intestine. We conducted a prospective cohort study at Avalon Beach, California (USA), where the indicator relationship is potentially affected by the discharge of sewage-contaminated groundwater and by solar radiation levels at this shallow, relatively quiescent beach. The goals of this study were to determine: 1) if swimmers exposed to marine water were at higher risk of illness than non-swimmers; 2) if FIB measured in marine water were associated with swimmer illness, and; 3) if the associations between FIB and swimmer health were modified by either submarine groundwater discharge or solar radiation levels. There were 7317 individuals recruited during the summers of 2007-08, 6165 (84%) of whom completed follow-up within two weeks of the beach visit. A total of 703 water quality samples were collected across multiple sites and time periods during recruitment days and analyzed for FIB using both culture-based and molecular methods. Adjusted odds ratios (AOR) indicated that swimmers who swallowed water were more likely to experience Gastrointestinal Illness (GI Illness) within three days of their beach visit than non-swimmers, and that this risk was significantly elevated when either submarine groundwater discharge was high (AOR [95% CI]:2.18 [1.22-3.89]) or solar radiation was low (2.45 [1.25-4.79]). The risk of GI Illness was not significantly elevated for swimmers who swallowed water when groundwater discharge was low or solar radiation was high. Associations between GI Illness incidence and FIB levels (Enterococcus EPA Method 1600) among swimmers who swallowed water were not significant when we did not account for groundwater discharge, but were strongly associated when groundwater discharge was high (1.85 [1.06, 3.23]) compared to when it was low (0.77 [0.42, 1.42]; test of interaction: P = 0.03). These results demonstrate the need to account for local environmental conditions when monitoring for, and making decisions about, public health at recreational beaches. The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.


Asunto(s)
Agua Subterránea/química , Agua Subterránea/microbiología , Adolescente , Adulto , Playas , California , Niño , Preescolar , Monitoreo del Ambiente/métodos , Heces/microbiología , Femenino , Enfermedades Gastrointestinales/etiología , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Factores de Riesgo , Aguas del Alcantarillado , Luz Solar , Natación , Factores de Tiempo , Eliminación de Residuos Líquidos/métodos , Microbiología del Agua , Contaminantes del Agua , Adulto Joven
20.
Am J Med Qual ; 27(6): 518-23, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22539797

RESUMEN

The objective of this study was to evaluate the effectiveness of a health communication campaign designed to reduce the rate of serious warfarin-related drug interactions. The B-SAFE campaign was conducted in 2009 to educate patients located in a Michigan hospital's service area about the risk of serious adverse drug events associated with warfarin. The rate of warfarin-related drug interactions among Medicare fee-for-service (FFS) patients admitted to the exposed hospital with hemorrhagic complications was compared with the rate of warfarin-related drug interactions among a similar cohort admitted to a control hospital before and after the campaign. The χ(2) test and logistic regression were used to analyze differences. The authors observed a marginally significant decline in the rate of warfarin-related drug interactions (odds ratio [OR] = 0.66; 95% confidence interval [CI] = 0.33-1.29) among FFS Medicare patients admitted for bleeding complications to the hospital targeted by the B-SAFE campaign. The same association was not observed in the control hospital (OR = 1.15; CI = 0.42-3.14). These findings suggest that patient exposure to the B-SAFE campaign may have resulted in a decrease in the rate of clinically significant warfarin-related drug interactions.


Asunto(s)
Anticoagulantes/efectos adversos , Promoción de la Salud , Educación del Paciente como Asunto/métodos , Warfarina/efectos adversos , Anciano , Anciano de 80 o más Años , Anticoagulantes/administración & dosificación , Interacciones Farmacológicas , Planes de Aranceles por Servicios , Femenino , Humanos , Masculino , Medicare , Evaluación de Programas y Proyectos de Salud , Estados Unidos , Warfarina/administración & dosificación
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