472 research outputs found

    In-vitro antimicrobial efficacy of Sri Lankan bee honey against microorganisms causing chronic wounds

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    Objectives: To evaluate the in-vitro efficacy of Sri Lankan bee honey as an antimicrobial agent againstpathogens causing chronic wounds.Methods: Standard strains of 4 bacterial and 4 fungal species and fourteen bacterial isolates fromchronic wounds were tested against twelve honey types belonging to seven Agro Ecological Regions(AERs). Antibacterial activity was determined by agar well diffusion, phenol equivalent methods andMinimum Inhibitory Concentration (MIC) by agar dilution.Results: 6/12, 5/12, 11/12 and 11/12 honeys gave inhibitory zones ranging 12.5-19.5 mm forStaphylococcus aureus (ATCC-25923), Escherichia coli (ATCC-25922), Pseudomonas aeruginosa(ATCC-27853) and Klebsiella pneumoniae (ATCC-700603) respectively. All ATCC strains had MICof 10-20%. Out of six selected honeys, four gave therapeutic level activity for all tested clinical isolatesexcept for Pseudomonas aeruginosa. Phenol equivalence values ranged 12-18% and 14-28% (w/v) fortested gram negative and positive bacterial species respectively. Honey originated from low countryregions reported phenol equivalence of 11-20% and superior activity against multidrug resistantbacteria. Commercially available honey reported lowest antibacterial activity with 5-10% phenolequivalence against 11/14 isolates. No inhibitory zones were observed for fungal species and MIC was>40% for all types of honey.Conclusions: Sri Lankan bee honey exhibits significant antibacterial activity against both gram positiveand negative bacteria including multidrug resistant organisms in-vitro. Antibacterial potency varies indifferent types of honey from different AERs. Low country honey was superior to others whileantibacterial activity of commercially available honey was negligible. None of the honeys hadantifungal activity against Candida species

    Evaluation of in-vivo and in-vitro microbiological methods for testing the efficacy of parenteral antibiotics: A Review

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    Antibiotics are available as innovators and generics. An innovator or branded drug is a medicine that is discovered, developed and marketed by a pharmaceutical company which also holds the patent for that drug. Generics only become available after the patent on the innovator expires. Generic drugs are required to have the same active ingredient, strength, dosage form, and route of administration as the innovator product. Generics should be bioequivalent to the innovator and when used, should have the same efficacy and safety profile. This is crucial for parenteral antibiotics because according to the World Health Organization and U.S. Food and Drug Administration criteria, parenteral generic products do not need to provide evidence for in-vivo bioavailability or bioequivalence before they can be marketed. Published evidence shows that there is a disparity in the efficacy of different generic antibiotic products. In-vitro microbiological methods of efficacy testing have been recognized as a standardized and cost-effective approach to clarify doubts regarding the efficacy of generic parenteral antibiotics. However, in-vitro methods used alone, might not be a good measurement of antibiotic efficacy as several studies have shown disparities between in-vitro and in-vivo efficacy of parenteral antibiotics.</p

    Monte-Carlo simulations of the recombination dynamics in porous silicon

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    A simple lattice model describing the recombination dynamics in visible light emitting porous Silicon is presented. In the model, each occupied lattice site represents a Si crystal of nanometer size. The disordered structure of porous Silicon is modeled by modified random percolation networks in two and three dimensions. Both correlated (excitons) and uncorrelated electron-hole pairs have been studied. Radiative and non-radiative processes as well as hopping between nearest neighbor occupied sites are taken into account. By means of extensive Monte-Carlo simulations, we show that the recombination dynamics in porous Silicon is due to a dispersive diffusion of excitons in a disordered arrangement of interconnected Si quantum dots. The simulated luminescence decay for the excitons shows a stretched exponential lineshape while for uncorrelated electron-hole pairs a power law decay is suggested. Our results successfully account for the recombination dynamics recently observed in the experiments. The present model is a prototype for a larger class of models describing diffusion of particles in a complex disordered system.Comment: 33 pages, RevTeX, 19 figures available on request to [email protected]

    The clinical presentation of monkeypox: a retrospective case-control study of patients with possible or probable monkeypox in a West London cohort

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    Objectives: Since May 2022, cases of human monkeypox virus (hMPXV) with human-to-human cross-transmission have significantly increased in non-endemic countries. Our aim was to characterise diagnostic features of patients with confirmed and possible monkeypox to guide future risk stratification, and to describe a virtual care model. Methods: We performed a retrospective case-control study of 140 patients assessed and screened for suspected monkeypox; on hMPXV PCR testing, 70 were confirmed positive and 70 negative. Data were compared to generate odds ratios of demographic and clinical features. Results: Positive patients were predominantly cis-male (99%) and self-identified as gay, bisexual and other men who have sex with men (GBMSM) (94%). Lymphadenopathy at presentation was associated with a higher likelihood of a positive result (OR 7.69 [95% CI 3.58, 16.51]). Positive patients were more likely to have a rash affecting the genital (OR 5.38 [95% CI 2.57, 11.23]) or buttocks/perianal region (OR 3.79 [1.70, 8.45]) compared with negative controls. 79% of patients engaged with virtual ward follow-up. Conclusions: These data can inform a risk-based approach to management of suspected monkeypox in GBMSM populations. Lymphadenopathy at presentation and the location of the rash were more associated with a positive hMPXV result. Health authorities can consider a virtual ward approach in the hMPXV outbreak

    Dynamics of live oil droplets and natural gas bubbles in deep water

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    Explaining the dynamics of gas-saturated live petroleum in deep water remains a challenge. Recently, Pesch et al. (Environ. Eng. Sci. 2018, 35, 289−299) reported laboratory experiments on methane-saturated oil droplets under emulated deep-water conditions, providing an opportunity to elucidate the underlying dynamical processes. We explain these observations with the Texas A&M Oil spill/Outfall Calculator (TAMOC), which models the pressure-, temperature-, and composition-dependent interactions between: oil-gas phase transfer; aqueous dissolution; and densities and volumes of liquid oil droplets, gas bubbles, and two-phase droplet-bubble pairs. TAMOC reveals that aqueous dissolution removed >95% of the methane from ~3.5-mm live oil droplets within 14.5 min, prior to gas bubble formation, during the experiments of Pesch et al. Additional simulations indicate that aqueous dissolution, fluid density changes, and gas-oil phase transitions (ebullition, condensation) may all contribute to the fates of live oil and gas in deep water, depending on the release conditions. Illustrative model scenarios suggest that 5-mm diameter gas bubbles released at <470 m water depth can transport methane, ethane, and propane to the water surface. Ethane and propane can reach the water surface from much deeper releases of 5-mm diameter live oil droplets, during which ebullition occurs at water depths of <70 m

    Electrochemical integration of graphene with light absorbing copper-based thin films

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    We present an electrochemical route for the integration of graphene with light sensitive copper-based alloys used in optoelectronic applications. Graphene grown using chemical vapor deposition (CVD) transferred to glass is found to be a robust substrate on which photoconductive Cu_{x}S films of 1-2 um thickness can be deposited. The effect of growth parameters on the morphology and photoconductivity of Cu_{x}S films is presented. Current-voltage characterization and photoconductivity decay experiments are performed with graphene as one contact and silver epoxy as the other

    Progress in operational modeling in support of oil spill response

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    Following the 2010 Deepwater Horizon accident of a massive blow-out in the Gulf of Mexico, scientists from government, industry, and academia collaborated to advance oil spill modeling and share best practices in model algorithms, parameterizations, and application protocols. This synergy was greatly enhanced by research funded under the Gulf of Mexico Research Initiative (GoMRI), a 10-year enterprise that allowed unprecedented collection of observations and data products, novel experiments, and international collaborations that focused on the Gulf of Mexico, but resulted in the generation of scientific findings and tools of broader value. Operational oil spill modeling greatly benefited from research during the GoMRI decade. This paper provides a comprehensive synthesis of the related scientific advances, remaining challenges, and future outlook. Two main modeling components are discussed: Ocean circulation and oil spill models, to provide details on all attributes that contribute to the success and limitations of the integrated oil spill forecasts. These forecasts are discussed in tandem with uncertainty factors and methods to mitigate them. The paper focuses on operational aspects of oil spill modeling and forecasting, including examples of international operational center practices, observational needs, communication protocols, and promising new methodologies
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