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J Am Chem Soc ; 141(34): 13487-13496, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31379152


In contrast to molecular systems, which are defined with atomic precision, nanomaterials generally show some heterogeneity in size, shape, and composition. The sample inhomogeneity translates into a distribution of energy levels, band gaps, work functions, and other characteristics, which detrimentally affect practically every property of functional nanomaterials. We discuss a novel synthetic strategy, colloidal atomic layer deposition (c-ALD) with stationary reactant phases, which largely circumvents the limitations of traditional colloidal syntheses of nano-heterostructures with atomic precision. This approach allows for significant reduction of inhomogeneity in nanomaterials in complex nanostructures without compromising their structural perfection and enables the synthesis of epitaxial nano-heterostructures of unprecedented complexity. The improved synthetic control ultimately enables bandgap and strain engineering in colloidal nanomaterials with close to atomic accuracy. To demonstrate the power of the new c-ALD method, we synthesize a library of complex II-VI semiconductor nanoplatelet heterostructures. By combining spectroscopic and computational studies, we elucidate the subtle interplay between quantum confinement and strain effects on the optical properties of semiconductor nanostructures.

Environ Sci Process Impacts ; 17(11): 1892-903, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26420634


This study examined the kinetics of photoreduction of Hg(ii) and photodemethylation of methylmercury (MeHg(+)) attached to, or in the presence of, dissolved organic matter (DOM). Both Hg(ii) and MeHg(+) are principally bound to reduced sulfur groups associated with DOM in many freshwater systems. We propose that a direct photolysis mechanism is plausible for reduction of Hg(ii) bound to reduced sulfur groups on DOM while an indirect mechanism is supported for photodemethylation of MeHg(+) bound to DOM. UV spectra of Hg(ii) and MeHg(+) bound to thiol containing molecules demonstrate that the Hg(ii)-S bond is capable of absorbing UV-light in the solar spectrum to a much greater extent than MeHg(+)-S bonds. Experiments with chemically distinct DOM isolates suggest that concentration of DOM matters little in the photochemistry if there are enough reduced S sites present to strongly bind MeHg(+) and Hg(ii); DOM concentration does not play a prominent role in photodemethylation other than to screen light, which was demonstrated in a field experiment in the highly colored St. Louis River where photodemethylation was not observed at depths ≥ 10 cm. Experiments with thiol ligands yielded slower photodegradation rates for MeHg(+) than in experiments with DOM and thiols; rates in the presence of DOM alone were the fastest supporting an intra-DOM mechanism. Hg(ii) photoreduction rates, however, were similar in experiments with only DOM, thiols plus DOM, or only thiols suggesting a direct photolysis mechanism. Quenching experiments also support the existence of an intra-DOM photodemethylation mechanism for MeHg(+). Utilizing the difference in photodemethylation rates measured for MeHg(+) attached to DOM or thiol ligands, the binding constant for MeHg(+) attached to thiol groups on DOM was estimated to be 10(16.7).

Mercúrio/química , Modelos Químicos , Poluentes Químicos da Água/química , Monitoramento Ambiental , Compostos de Metilmercúrio/química , Fotólise , Compostos de Sulfidrila/química , Luz Solar
Compend Contin Educ Vet ; 32(5): E1-7; quiz E8, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20949419


Prevention of nosocomial infection begins with the hospital layout and identification of special considerations for particular patients. The construction of a new hospital or renovation of an existing hospital requires careful planning and consideration of the needs of the expected patient population and hospital staff. This article discusses considerations for preventing cross-contamination of pathogens through hospital design, as well as special considerations for particular patients, specifically those in isolation areas and surgical suites.

Infecção Hospitalar/veterinária , Arquitetura de Instituições de Saúde/normas , Hospitais Veterinários/normas , Higiene , Animais , Infecção Hospitalar/prevenção & controle , Guias como Assunto , Humanos
Compend Contin Educ Vet ; 32(5): E1-11; quiz E12, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20949420


Antibiotic resistance is a growing problem in the hospital setting. Organisms that cause hospital-acquired infections are generally highly resistant, requiring expensive antibiotics and further hospitalization. As a result, many owners of infected pets choose euthanasia. Appropriate hospital disinfection and staff hygiene practices can prevent such infections by reducing the pathogen load in a facility in accordance with the "nosocomial prevention triad"-appropriate antibiotic usage, staff and patient hygiene, and hospital maintenance and disinfection. This review outlines the development and implementation of hospital disinfection protocols and hand hygiene practices in small animal veterinary hospitals.

Infecção Hospitalar/veterinária , Arquitetura de Instituições de Saúde/normas , Desinfecção das Mãos/normas , Hospitais Veterinários/normas , Higiene , Animais , Infecção Hospitalar/prevenção & controle , Resistência a Medicamentos , Humanos , Guias de Prática Clínica como Assunto