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1.
Environ Sci Technol ; 52(15): 8588-8595, 2018 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-29916696

RESUMO

Reverse osmosis (RO)-based desalination and advanced water purification facilities have inherent challenges associated with concentrate management and disposal. Although enhanced permeate recovery and concentrate minimization are desired, membrane scaling due to inorganic constituents, such as silica, calcium, phosphate, and iron, hinders the process. To solve this problem, a new diatom-based photobiological process has been developed to remove these scaling constituents by biological uptake and precipitation. In this study, RO concentrate samples were collected from a full-scale advanced water reclamation facility in California and were treated in 3.8 and 57 L photobioreactors inoculated with a brackish water diatom  Pseudostaurosira trainorii PEWL001 using light-emitting diode bulbs or natural sunlight as a light source. The photobiological treatment removed 95% of reactive silica and 64% of calcium and enabled additional water recovery using a secondary RO at a recovery rate up to 66%. This represents 95% overall recovery, including 85% recovery in the primary RO unit. In addition to the scaling constituents, the photobiological treatment removed 12 pharmaceuticals and personal care products, as well as N-nitrosodimethylamine, from RO concentrate samples primarily via photolysis. This novel approach has a strong potential for application to brackish water desalination and advanced water purification in arid and semiarid areas.


Assuntos
Purificação da Água , California , Membranas Artificiais , Osmose , Eliminação de Resíduos Líquidos , Água
2.
Development ; 139(16): 2945-54, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22764052

RESUMO

Dynein, a microtubule motor complex, plays crucial roles in cell-cycle progression in many systems. The LIS1 accessory protein directly binds dynein, although its precise role in regulating dynein remains unclear. Mutation of human LIS1 causes lissencephaly, a developmental brain disorder. To gain insight into the in vivo functions of LIS1, we characterized a male-sterile allele of the Drosophila homolog of human LIS1. We found that centrosomes do not properly detach from the cell cortex at the onset of meiosis in most Lis-1 spermatocytes; centrosomes that do break cortical associations fail to attach to the nucleus. In Lis-1 spermatids, we observed loss of attachments between the nucleus, basal body and mitochondria. The localization pattern of LIS-1 protein throughout Drosophila spermatogenesis mirrors that of dynein. We show that dynein recruitment to the nuclear surface and spindle poles is severely reduced in Lis-1 male germ cells. We propose that Lis-1 spermatogenesis phenotypes are due to loss of dynein regulation, as we observed similar phenotypes in flies null for Tctex-1, a dynein light chain. We have previously identified asunder (asun) as another regulator of dynein localization and centrosome positioning during Drosophila spermatogenesis. We now report that Lis-1 is a strong dominant enhancer of asun and that localization of LIS-1 in male germ cells is ASUN dependent. We found that Drosophila LIS-1 and ASUN colocalize and coimmunoprecipitate from transfected cells, suggesting that they function within a common complex. We present a model in which Lis-1 and asun cooperate to regulate dynein localization and centrosome positioning during Drosophila spermatogenesis.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas de Drosophila/metabolismo , Dineínas/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Espermatogênese/fisiologia , Animais , Animais Geneticamente Modificados , Proteínas de Ciclo Celular/genética , Centrossomo/metabolismo , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Complexo Dinactina , Dineínas/genética , Humanos , Masculino , Proteínas Associadas aos Microtúbulos/genética , Modelos Biológicos , Fenótipo , Espermátides/metabolismo , Espermátides/ultraestrutura , Espermatócitos/metabolismo , Espermatócitos/ultraestrutura , Espermatogênese/genética
3.
Healthc Pap ; 20(4): 77-81, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-36433913

RESUMO

The constraints of the COVID-19 pandemic accelerated the adoption of virtual care. The role of virtual care in the mix of healthcare services is being re-examined as the pandemic evolves. For many diverse Indigenous communities (rural, remote, urban), virtual care has the potential to increase access to healthcare and improv health outcomes, or to worsen existing inequities. Thoughtful co-design of virtual care programs, attention to user experience and enabling policy decisions can unlock the potential of virtual care for Indigenous individuals and communities.


Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , Pandemias , População Rural , Canadá/epidemiologia
4.
ACS Appl Mater Interfaces ; 14(38): 43558-43567, 2022 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-36099398

RESUMO

Roll-to-roll coating of conventional organic photovoltaic architectures in air necessitates low work function, electron-harvesting interlayers as the top interface, termed cathode interlayers. Traditional materials based on metal oxides are often not compatible with coating in air and/or green solvents, require thermal annealing, and are limited in feasibility due to interactions with underlying layers. Alternatively, perylene diimide materials offer easily tunable redox properties, are amenable to air coating in green solvents, and are considered champion organic-based cathode interlayers. However, underlying mechanisms of the extraction of photogenerated electrons are less well understood. Herein, we demonstrate the utilization of two N-annulated perylene diimide materials, namely, PDIN-H and CN-PDIN-H, in air-processed conventional organic photovoltaic devices, using the now standard PM6:Y6 photoactive layer. The processing ink formulation using cesium carbonate as a processing agent to solubilize the perylene diimides in suitable green solvents (1-propanol and ethyl acetate) for uniform film formation using spin or slot-die coating on top of the photoactive layer is critical. Cesium carbonate remains in the film, creating hybrid organic/metal salt cathode interlayers. Best organic photovoltaic devices have power conversion efficiencies of 13.2% with a spin-coated interlayer and 13.1% with a slot-die-coated interlayer, superior to control devices using the classic conjugated polyelectrolyte PFN-Br as an interlayer (ca. 12.8%). The cathode interlayers were found to be semi-insulating in nature, and the device performance improvements were attributed to beneficial interfacial effects and electron tunneling through sufficiently thin layers. The efficiencies beyond 13% achieved in air-processed organic photovoltaic devices utilizing slot-die-coated cathode interlayers are among the highest reported so far, opening new opportunities for the fabrication of large-area solar cell modules.

5.
ACS Appl Mater Interfaces ; 13(37): 44641-44655, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34496216

RESUMO

State-of-the-art organic photovoltaic (OPV) materials are composed of complex, chemically diverse polymeric and molecular structures that form highly intricate solid-state interactions, collectively yielding exceptional tunability in performance and aesthetics. These properties are especially attractive for semitransparent power-generating windows or shades in living environments, greenhouses, or other architectural integrations. However, before such a future is realized, a broader and deeper understanding of property stability must be acquired. Stability during operating and environmental conditions is critical, namely, material color steadfastness, optoelectronic performance retention, morphological rigidity, and chemical robustness. To date, no single investigation encompasses all four distinct, yet interconnected, metrics. Here, we present a multimodal strategy that captures a dynamic and interconnected evolution of each property during the course of an accelerated photobleaching experiment. We demonstrate this approach across relevant length scales (from molecular to visual macroscale) using X-ray photoelectron spectroscopy, grazing-incidence X-ray scattering, microwave conductivity, and time-dependent photobleaching spectroscopies for two high-performance semitransparent OPV blends-PDPP4T:PC60BM and PDPP4T:IEICO-4F, with comparisons to the stabilities of the individual components. We present direct evidence that specific molecular acceptor (fullerene vs nonfullerene) designs and the resulting donor-acceptor interactions lead to distinctly different mechanistic routes that ultimately arrive at what is termed "OPV degradation." We directly observe a chemical oxidation of the cyano endcaps of the IEICO-4F that coincides with a morphological change and large loss in photoconductivity while the fullerene acceptor-containing blend demonstrates a significantly greater fraction of oxygen uptake but retains 55% of the photoconductivity. This experimental roadmap provides meaningful guidance for future high-throughput, multimodal studies, benchmarking the sensitivity of the different analytical techniques for assessing stability in printable active layers, independent of complete device architectures.

6.
ACS Appl Mater Interfaces ; 13(41): 49096-49103, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34636554

RESUMO

In this work, we report the formation of perylene diimide films, from green solvents, for use as electron transporting layers, when combined with ZnO, in inverted-type organic photovoltaics. A modified N-annulated PDI was functionalized with a tert-butyloxycarbonyl protecting group to solubilize the material, enabling solution processing from green solvents. Post-deposition treatment of films via thermal annealing cleaves the protecting group yielding the known PDIN-H material, rendering films solvent-resistant. The PDIN-H films were characterized by optical absorption spectroscopy, contact angle measurements, and atomic force microscopy. When used to modify the surface of ZnO in inverted-type organic photovoltaics (air-processed and tested) based on the PM6:Y6 and PTQ10:Y6 bulk-heterojunctions, the device power conversion efficiency increases from 9.8 to 11.0% and 7.2 to 9.8%, respectively.

7.
MicroPubl Biol ; 20212021 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-33474526

RESUMO

Genetic screens have been used to identify genes involved in the regulation of different biological processes. We identified growth mutants in a Flp/FRT screen using the Drosophila melanogaster eye to identify conditional regulators of cell growth and cell division. One mutant identified from this screen, B.2.16, was mapped and characterized by researchers in undergraduate genetics labs as part of the Fly-CURE. We find that B.2.16 is a non-lethal genetic modifier of the Dark82 mosaic eye phenotype.

8.
Dev Cell ; 8(3): 435-42, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15737938

RESUMO

Although traditional organism-based mutational analysis is powerful in identifying genes involved in specific biological processes, limitations include incomplete coverage and time required for gene identification. Biochemical screens using cell transfection or yeast two-hybrid methods are rapid, but they are limited by cDNA library quality. The recent establishment of "uni-gene sets" has made it feasible to biochemically screen an organism's entire genome. Radiolabeled protein pools prepared from the Drosophila Gene Collection were used in a Drosophila in vitro expression cloning ("DIVEC") screen for substrates of PAN GU kinase, which is crucial for S-M embryonic cell cycles. Ablation of one identified substrate, Mat89Bb, by RNAi produces a polyploid phenotype similar to that of pan gu mutants. Xenopus embryos injected with Mat89Bb morpholinos arrest with polyploid nuclei, and Mat89Bb RNAi in HeLa cells gives rise to multinucleated cells. Thus, Mat89Bb plays an evolutionarily conserved role as a crucial regulator of both cell cycle and development.


Assuntos
Ciclo Celular/fisiologia , Proteínas de Drosophila/metabolismo , Embrião não Mamífero/enzimologia , Desenvolvimento Embrionário/fisiologia , Genoma , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Clonagem Molecular , Drosophila/embriologia , Drosophila/enzimologia , Proteínas de Drosophila/genética , Embrião não Mamífero/citologia , Células HeLa , Humanos , Proteínas Serina-Treonina Quinases/genética , Especificidade por Substrato/genética , Xenopus/embriologia , Xenopus/metabolismo
9.
ACS Appl Mater Interfaces ; 12(39): 43684-43693, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32946216

RESUMO

Efficient organic photovoltaics (OPVs) based on slot-die-coated (SD) ternary blends were developed for low-intensity indoor light harvesting. For active layers processed in air and from eco-friendly solvents, our device performances (under 1 sun and low light intensity) are the highest reported values for fluoro-dithiophenyl-benzothiadiazole donor polymer-based OPVs. The N-annulated perylene diimide dimer acceptor was incorporated into a blend of donor polymer (FBT) and fullerene acceptor (PC61BM) to give ternary bulk heterojunction blends. SD ternary-based devices under 1 sun illumination showed enhanced power conversion efficiency (PCE) from 6.8 to 7.7%. We observed enhancement in the short-circuit current density and open-circuit voltage of the devices. Under low light intensity light-emitting device illumination (ca. 2000 lux), the ternary-based devices achieved a PCE of 14.0% and a maximum power density of 79 µW/cm2 compared to a PCE of 12.0% and a maximum power density of 68 µW/cm2 for binary-based devices. Under the same illumination conditions, the spin-coated (SC) devices showed a PCE of 15.5% and a maximum power density of 88 µW/cm2. Collectively, these results demonstrate the exceptional promise of a SD ternary blend system for indoor light harvesting and the need to optimize active layers based on industry-relevant coating approaches toward mini modules.

10.
Vet Microbiol ; 128(1-2): 204-6, 2008 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-18006252

RESUMO

Diagnosis of Clostridium difficile-associated disease (CDAD) in neonatal pigs is accomplished, in part, by detection of toxins A (TcdA) and B (TcdB) in feces or colonic contents. Samples (n=115) were tested simultaneously with two toxin assays (Clostridium difficile Tox A/B II, TechLab, Blacksburg, VA; Gastro-tect Clostridium difficile Toxin A+B, Medical Chemical Corporation). Previous comparison of the Tox A/B II assay to the reference method (toxicity in CHO cell monolayers) revealed an overall correlation of 88%, with 91% sensitivity and 86% specificity, a positive predictive value of 86 and a negative predictive value of 84. In comparing the two EIAs, a group of nine samples were positive in both assays and a group of 92 were negative in both. However, 14 samples positive in the Tox A/B II were negative in the Gastro-tect assay. Thus, in comparison to the Tox A/B II assay, the Gastro-tect assay was 100% specific but only 39% sensitive. Its negative predictive value was 87, but its positive predictive value was 100. Thus, the Tox A/B II kit is apparently superior to the Gastro-tect Toxin A+B test for diagnosis of CDAD in neonatal pigs.


Assuntos
Proteínas de Bactérias/análise , Toxinas Bacterianas/análise , Clostridioides difficile/isolamento & purificação , Enterocolite Pseudomembranosa/veterinária , Enterotoxinas/análise , Técnicas Imunoenzimáticas/veterinária , Doenças dos Suínos/diagnóstico , Animais , Anticorpos Antibacterianos/análise , Anticorpos Antibacterianos/metabolismo , Clostridioides difficile/imunologia , Colo/química , Enterocolite Pseudomembranosa/diagnóstico , Enterocolite Pseudomembranosa/imunologia , Fezes/química , Conteúdo Gastrointestinal/química , Técnicas Imunoenzimáticas/métodos , Técnicas Imunoenzimáticas/normas , Valor Preditivo dos Testes , Suínos , Doenças dos Suínos/imunologia
11.
Sci Total Environ ; 406(1-2): 205-18, 2008 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-18760446

RESUMO

The Salton Sea is a large shallow saline lake located in southern California that is noted for high sulfate concentrations, substantial algal productivity, and very warm water column temperatures. These conditions are well-suited for sulfide production, and sulfide has been implicated in summer fish kills, although no studies have been conducted to specifically understand hydrogen sulfide production and volatilization there. Despite polymictic mixing patterns and relatively short accumulation periods, the amount of sulfide produced is comparable to meromictic lakes. Sulfide levels in the Salton Sea reached concentrations of 1.2 mmol L(-1) of total free sulfide in the hypolimnion and 5.6 mmol L(-1) in the sediment pore water. Strong winds in late July mixed H2S into the surface water, where it depleted the entire water column of dissolved oxygen and reached a concentration of 0.1 mmol L(-1). Sulfide concentrations exceeded the toxicity threshold of tilapia (Oreochromis mossambicus) and combined with strong anoxia throughout the water column, resulted in a massive fish kill. The mixing of sulfide into the surface waters also increased atmospheric H2S concentrations, reaching 1.0 micromol m(-3). The flux of sulfide from the sediment into the water column was estimated to range from 2-3 mmol m(-2) day(-1) during the winter and up to 8 mmol m(-2) day(-1) during the summer. Application of the two-layer model for volatilization indicates that up to 19 mmol m(-2) day(-1) volatilized from the surface during the mixing event. We estimate that as much as 3400 Mg year(-1) or approximately 26% of sulfide that diffused into the water column from the deepest sediments may have been volatilized to the atmosphere.


Assuntos
Monitoramento Ambiental/métodos , Água Doce/química , Sedimentos Geológicos/análise , Sulfeto de Hidrogênio/análise , Cloreto de Sódio/química , Poluentes Químicos da Água/análise , Animais , California , Eutrofização , Sedimentos Geológicos/química , Sulfeto de Hidrogênio/química , Hipóxia , Porosidade , Estações do Ano , Sulfatos/análise , Sulfatos/química , Temperatura , Tilápia/fisiologia , Fatores de Tempo , Volatilização , Poluentes Químicos da Água/química
12.
Chemosphere ; 192: 244-249, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29107875

RESUMO

Monochloramine is a secondary disinfectant used in drinking water and is also formed in chlorinated wastewater. While known to hydrolyze over time and react with dissolved organic matter, its partitioning between the aqueous and gas phase has not been extensively studied. Preliminary experiments demonstrated that monochloramine concentrations in solutions open to the atmosphere or actively aerated decreased more rapidly than in sealed solutions, indicating significant losses to the atmosphere. For example, a monochloramine solution open to the atmosphere yielded a loss rate constant of 0.08 d-1, a value twice that for sealed samples without headspace (0.04 d-1) where loss occurs exclusively as a result of hydrolysis. A solution aerated at 10 mL s-1 had a loss rate constant nearly 10× greater than that for hydrolysis alone (0.35 d-1). To better understand partitioning of monochloramine to the gas phase and potential for volatilization, the dimensionless Henry's law constants of monochloramine (KH) were determined using an equilibrium headspace technique at five different temperatures (11, 16, 21, 27, and 32 °C). The resulting values ranged from 8 × 10-3 to 4 × 10-2, indicating a semi-volatile compound, and were found to be consistent with quantitative structure activity relationship predictions. At 20 °C, monochloramine exhibits a dimensionless Henry's constant of about 1.7 × 10-2 which is 35 times greater than ammonia but comparable to the Henry's constant of inorganic semi-volatile compounds such sulfur dioxide. The Henry's constant values for monochloramine suggests that volatilization could be a relevant loss process in open systems such as rivers receiving chlorinated wastewater effluent, swimming pools and cooling towers.


Assuntos
Algoritmos , Cloraminas/química , Desinfetantes/química , Água Potável/análise , Atmosfera , Cloraminas/análise , Desinfetantes/análise , Água Potável/química , Volatilização
13.
Vet Microbiol ; 124(3-4): 358-61, 2007 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-17493774

RESUMO

Clostridium difficile is widely known as a cause of disease in humans, and has emerged as an important problem in neonatal swine. No commercial product is available for immunoprophylaxis of C. difficile-associated disease, but success in preventing experimental infections in hamsters by use of nontoxigenic strains to competitively exclude toxigenic strains led us to try this method in neonatal pigs. Spores were administered orally to newborn pigs or were sprayed onto perineum and teats of dams. Significantly more piglets were weaned among litters receiving spores orally, and average weaning weights were significantly higher for both treatment groups than for controls. Toxins A and B were detected in 44.8% of litters and 16.5% of piglets born to sprayed sows and 58.3% of litters and 15.4% of piglets in the control group. However, toxins were detected in only 13.8% of litters and 3.4% of piglets given spores orally. These data support a contention that precolonization by a nontoxigenic strain can ameliorate the pre-weaning growth retardation associated with C. difficile infection in piglets.


Assuntos
Toxinas Bacterianas/metabolismo , Clostridioides difficile , Enterocolite Pseudomembranosa/veterinária , Probióticos , Doenças dos Suínos/prevenção & controle , Animais , Animais Recém-Nascidos , Aderência Bacteriana , Clostridioides difficile/crescimento & desenvolvimento , Clostridioides difficile/patogenicidade , Clostridioides difficile/fisiologia , Enterocolite Pseudomembranosa/microbiologia , Enterocolite Pseudomembranosa/prevenção & controle , Feminino , Gravidez , Distribuição Aleatória , Esporos Bacterianos , Suínos , Doenças dos Suínos/microbiologia , Desmame , Aumento de Peso
14.
J Contin Educ Health Prof ; 27(4): 214-9, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18085600

RESUMO

INTRODUCTION: Many physicians seek information from colleagues over other sources, highlighting the important role of interaction in continuing professional development (CPD). To guide the development of CPD opportunities, this study explored the nature of cancer-related questions faced by general surgeons, and how interaction with colleagues addressed those questions. METHODS: This study involved thematic analysis of field notes collected through observation and transcripts of telephone interviews with 20 surgeons, two pathologists, one medical oncologist, and one radiation oncologist affiliated with six community hospitals participating in multidisciplinary cancer conferences by videoconference in one region of Ontario, Canada. RESULTS: Six multidisciplinary cancer conferences (MCCs) were observed between April and September 2006, and 11 interviews were conducted between December 2006 and January 2007. Sharing of clinical experience made possible collective decision making for complex cancer cases. Physicians thought that collegial interaction improved awareness of current evidence, patient satisfaction with treatment plans, appropriate care delivery, and continuity. By comparing proposed treatment with that of the group and gaining exposure to decision making for more cases than they would see in their own practices, physicians developed clinical expertise that could be applied to future cases. Little collegial interaction occurred outside these organized sessions. DISCUSSION: These findings highlight the role of formally coordinated collegial interaction as an important means of CPD for general surgeons. Investment may be required for infrastructure to support such efforts and for release of health professional time for participation. Further research is required to examine direct and indirect outcomes of collegial interaction.


Assuntos
Educação Médica Continuada , Disseminação de Informação , Relações Interprofissionais , Médicos , Protocolos Clínicos , Tomada de Decisões , Humanos , Entrevistas como Assunto , Neoplasias/terapia , Ontário , Comunicação por Videoconferência
15.
Water Res ; 41(19): 4457-67, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17624395

RESUMO

A 3-year study was conducted to quantify the effectiveness of a destratification system on weakening thermal stratification and increasing dissolved oxygen (DO) levels in Lake Elsinore, California. Biweekly measurements of temperature, DO, and other parameters were made at 14 sites across the lake beginning in July 2003. A destratification system consisting of 20 axial flow pumps fitted with 3 HP electric motors and 1.8m diameter impellers mounted 2m below the water surface was installed in the spring of 2004 and made fully operational in July 2004. An unusually wet winter of 2005 raised the summer mean depth from 3.0m in 2004 to 6.7 m in 2005. This study thus allowed us to quantify the influence of axial flow pump operation on water column properties under shallow water conditions (i.e., before and after axial flow pump installation), and also to compare the effectiveness of the destratification system at two strongly different lake levels. Transparencies increased substantially after the winter storms in 2005 and thermal stability was shown to be strongly dependent upon lake level. Stratification and a large area of anoxic sediments persisted despite pump operation in the summers of 2004 and 2005. Acoustic Doppler current profiler (ADCP) measurements showed that mixing energy was not being efficiently transmitted laterally into the water column.


Assuntos
Água/normas , California , Água Doce , Conceitos Meteorológicos , Oxigênio/análise , Temperatura
16.
Water Res ; 40(5): 911-6, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16480755

RESUMO

Alum is often added to eutrophic lakes to limit the release of phosphorus from sediments. This study quantified the effect of age and extent of crystallization on the phosphate (PO4-P) sorption capacity of alum floc. Aluminum hydroxide flocs were formed from alum addition at a dose of 25 mg/L of Al3+ to Big Bear Lake waters returned to the laboratory; flocs were then aged for 4, 20, 50, 120, and 180 days in the treated lake waters. The physical and mineralogical properties of the alum floc were characterized using surface area and thermal analyses. Phosphate sorption to the floc was evaluated using filtered lake water and NaCl/NaHCO3 solutions spiked with PO4-P concentrations ranging from 0 to 100 mg/L. The Langmuir model provided reasonable fits to data (r2 = 0.97-1.00), from which sorption constants and sorption maxima were determined. Phosphate sorption decreased with increased floc age and crystallinity and decreased surface area. Phosphate sorption maximum of the alum floc aged for 6 months was about 50% lower than freshly precipitated floc, while the binding constant, Kads, decreased approximately 65% over this same time period.


Assuntos
Compostos de Alúmen/química , Hidróxido de Alumínio/química , Água Doce/química , Fósforo/química , Adsorção , Fatores de Tempo , Poluentes Químicos da Água/análise
17.
Water Res ; 39(16): 3918-28, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16139325

RESUMO

Water samples from two southern California lakes adversely affected by internal nutrient loading were treated with a 20 mg/L dose of Al3+ in laboratory studies to examine Al solubility and solid-phase speciation over time. Alum [Al2(SO4)3 . 18 H2O] applications to water samples from Big Bear Lake and Lake Elsinore resulted in a rapid initial decrease in pH and alkalinity followed by a gradual recovery in pH over several weeks. Dissolved Al concentrations increased following treatment, reaching a maximum of 2.54 mg/L after 17 days in Lake Elsinore water and 0.91 mg/L after 48 days in Big Bear Lake water; concentrations in both waters then decreased to <0.25 mg/L after 150 days. The solid phase was periodically collected and analyzed using X-ray diffraction (XRD), differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), scanning electron microscopy (SEM), and surface area analyses to investigate the nature of the reaction products and crystallinity development over time. Poorly ordered, X-ray amorphous solid phases transformed over time to relatively well-ordered gibbsite, with strong diffraction peaks at 4.8 and 4.3 A. XRD also indicated the formation of a second (possibly aluminosilicate) crystalline phase after 150 days in Lake Elsinore water. Surface areas also decreased over time as crystals reordered to form gibbsite/microcrystalline gibbsite species. DSC-TGA results suggested that the initially formed amorphous Al(OH)3 underwent transformation to >45% gibbsite. These results were supported by geochemical modeling using Visual MINTEQ, with Al solubility putatively controlled by amorphous Al(OH)3 shortly after treatment and approaching that of microcrystalline gibbsite after about 150 days. These findings indicate that Al(OH)3 formed after alum treatment undergoes significant chemical and mineralogical changes that may alter its effectiveness as a reactive barrier to phosphorus release from lake sediments.


Assuntos
Compostos de Alúmen/química , Alumínio/química , California , Monitoramento Ambiental , Microscopia Eletrônica de Varredura , Solubilidade , Abastecimento de Água , Difração de Raios X
18.
Water Res ; 39(7): 1277-88, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15862327

RESUMO

The spatial and temporal distributions of indicator bacteria in a small, multiple-use source drinking water reservoir in Southern California, USA were quantified over the period August 2001-July 2002. High levels of total and fecal coliform bacteria were present in Canyon Lake (annual geometric mean concentrations+/-SEM of 3.93+/-0.02 and 3.02+/-0.03 log cfu/100mL, respectively), while comparatively low levels of enterococci and E. coli were found (1.16+/-0.02 log cfu/100mL and 0.30+/-0.03 log MPN/100mL, respectively). As a result, these different indicator bacteria yielded quite divergent indices of water quality, with 72.1% of all surface samples (n=294) exceeding the USEPA single-sample limit of 400 cfu/100mL fecal coliform bacteria, while none (0%) of the samples exceeded the single-sample limit for E. coli (n=194). Regression analyses found a positive correlation between total and fecal coliform bacteria (R=0.50, significant at p<0.001) and between enterococci and E. coli (R=0.51, significant at p<0.001), but no correlation or inverse correlations were found between coliform concentrations and enterococci and E. coli levels. External sources responsible for the high total and fecal coliform bacteria were not identified, although laboratory studies demonstrated growth of the coliform bacteria in lake water samples. Enterococci and E. coli were not observed to grow, however. Bacteria concentrations varied relatively little laterally across the lake, although strong vertical gradients in fecal coliform and enterococcus bacteria concentrations were present during summer stratification, with concentrations about 10x higher above the thermocline when compared with surface concentrations. In contrast, total bacteria, total virus and total coliform bacteria levels were unchanged with depth. Seasonal trends in bacteria concentrations were also present. This study shows that the choice of indicator bacteria and sampling depth can both strongly affect the apparent microbial water quality of a lake or reservoir.


Assuntos
Enterobacteriaceae/isolamento & purificação , Microbiologia da Água , Abastecimento de Água , California , Contagem de Colônia Microbiana , Enterobacteriaceae/crescimento & desenvolvimento , Enterococcus/isolamento & purificação , Escherichia coli/isolamento & purificação , Fezes/microbiologia , Água Doce/microbiologia , Água Doce/virologia , Estações do Ano , Vírus/isolamento & purificação
19.
Aust Orthod J ; 21(1): 11-8, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-16433076

RESUMO

BACKGROUND: Most patients and their parents experience difficulty in fully appreciating the implications and demands of orthodontic treatment. This is largely because of inadequate understanding of the process of treatment or the commitment required. OBJECTIVES: To determine if a specifically developed video information package could significantly increase patient awareness of the implications of a full course of orthodontic treatment. Changes in attitude to orthodontic treatment after viewing the package were also measured. METHODS: Year 7 (12 year-old) students in two primary schools in the City of Gold Coast, Australia were randomly allocated to either a study group or a control group. Knowledge of and attitude to orthodontic treatment were measured with self-administered questionnaires before and after viewing the information package. RESULTS: The intervention group showed a 15 per cent gain in knowledge (p < 0.001). There was no gain in knowledge for the 45 students in the control group. There was no measured change in perception of need for orthodontic treatment in the study group. There was, however, an increase in potential compliance and positive attitude to the appearance of orthodontic appliances. There was a small increase in willingness to undertake treatment, but this was not statistically significant. CONCLUSIONS: The information package developed for this study increased awareness of the implications and practical difficulties which may be encountered during a course of orthodontic treatment, and produced some changes in attitude to treatment.


Assuntos
Atitude Frente a Saúde , Conhecimentos, Atitudes e Prática em Saúde , Ortodontia Corretiva , Educação de Pacientes como Assunto/métodos , Conscientização , Criança , Feminino , Humanos , Masculino , Aparelhos Ortodônticos , Ortodontia Corretiva/psicologia , Cooperação do Paciente , Queensland , Classe Social , Materiais de Ensino , Gravação de Videoteipe
20.
Mil Med ; 167(11): 944-9, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12448624

RESUMO

Suicide, violence, and unintentional injury have many risk factors in common, such as stress, emotional illness, and substance abuse, among others. Unfortunately, commanders and supervisors may be inadvertently overlooking behavioral risks military personnel engage in. Behavioral health force protection is defined as guarding military personnel from injury comprehensively by identifying shared risk factors and implementing protective factors. This approach broadens the arena of preventive health by addressing unintentional injuries, which may be overlooked as preventable. This paper highlights the relevance of clinicians, commanders, and supervisors being attentive to shared risk factors in the etiology of injury along a continuum encompassing suicide, unintentional injury, and violence. Leadership responsibility is discussed in the context of a military community network that provides a framework of support from both within the unit and external helping agencies as well.


Assuntos
Medicina Militar , Militares , Assunção de Riscos , Prevenção do Suicídio , Violência/prevenção & controle , Ferimentos e Lesões/prevenção & controle , Humanos , Liderança , Modelos Teóricos , Fatores de Risco
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