Toxicity of a polymer-graphene oxide composite against bacterial planktonic cells, biofilms, and mammalian cells

It is critical to develop highly effective antimicrobial agents that are not harmful to humans and do not present adverse effects on the environment. Although antimicrobial studies of graphene-based nanomaterials are still quite limited, some researchers have paid particular attention to such nanocomposites as promising candidates for the next generation of antimicrobial agents. The polyvinyl-N-carbazole (PVK)-graphene oxide (GO) nanocomposite (PVK-GO), which contains only 3 wt% of GO well-dispersed in a 97 wt% PVK matrix, presents excellent antibacterial properties without significant cytotoxicity to mammalian cells. The high polymer content in this nanocomposite makes future large-scale material manufacturing possible in a high-yield process of adiabatic bulk polymerization. In this study, the toxicity of PVK-GO was assessed with planktonic microbial cells, biofilms, and NIH 3T3 fibroblast cells. The antibacterial effects were evaluated against two Gram-negative bacteria: Escherichia coli and Cupriavidus metallidurans; and two Gram-positive bacteria: Bacillus subtilis and Rhodococcus opacus. The results show that the PVK-GO nanocomposite presents higher antimicrobial effects than the pristine GO. The effectiveness of the PVK-GO in solution was demonstrated as the nanocomposite "encapsulated" the bacterial cells, which led to reduced microbial metabolic activity and cell death. The fact that the PVK-GO did not present significant cytotoxicity to fibroblast cells offers a great opportunity for potential applications in important biomedical and industrial fields.     

Development of fragmentation models for solid fuel combustion and gasification as subroutines for inclusion in CFD codes

This work arises from substantial problems found in the modelling of the gasification and combustion of solid fuel, both coal and biomass in the following different systems:

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Coal fired non-slagging cyclone combustors.

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Pre-calciners on cement plant.

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Fuel rich inverted cyclone combustors used to simulate the time temperature history of large utility boilers.

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Cyclonic gasifiers for sawdust and direct firing of small gas turbines.

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Deposition studies for slagging and fouling in large utility boilers.

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Prediction of final carbon in ash from pulverised coal systems.

Commercial CFD codes such as Fluent are well developed and have well proven routines for lagrangian tracking of burning particles through complex flow fields. However what has become apparent in numerous studies is that existing models for solid fuel combustion can be adjusted to predict the initial flow field aerodynamics, sometimes the temperature, but fall down when particles have to be followed completely through a system. This is manifested with cyclone combustors and gasifiers via enhanced retention of burning particles in centrifugal force fields, which can only be resolved by changes in the particle size distribution and thus fragmentation as the particle gasify or burn. This problem also becomes apparent in studies of processes in pre-calciners and in deposition in large utility boilers and furnaces.The paper will review the literature of the fragmentation of pulverised coal and biomass during gasification, devolatilisation and combustion and relate it to observed phenomena in the type of system under consideration. The difficulties of incorporating models of fragmentation in CFD codes such as Fluent are discussed. Then the implementation of such a model in Fluent is described, together with results from a number of different systems. It is concluded that the model so implemented shows improved prediction in many difficult areas, but still needs development to better reflect actual fragmentation conditions in different experimental systems.It is concluded that the model needs to be further extended beyond the single step fragmentation at present used, especially to include many of the fine particles known to be generated in such systems.     

Pulp exposure after stepwise versus direct complete excavation of deep carious lesions in young posterior permanent teeth

Serum levels of alpha 1-antichymotrypsin (alpha 1-ACT), macroglobulin, alpha 1-antitrypsin, ceruloplasmin, acid glycoprotein, transferrin, and C-reactive protein were measured in patients with probable late onset dementia of Alzheimer type (I-AD), patients with vascular dementia (VD), healthy elderly (HC), and patients with chronic or acute inflammation. Three blood samples were taken at 10-15 day intervals. Serum alpha 1-ACT levels from first and second serum samples were elevated in one out of 11 I-AD patients. Serpin serum levels from the third sample were increased in four out of 11 I-AD patients. None of these patients showed increased levels of other acute phase proteins measured in the three serum samples. VD patients did not show abnormal serum levels of alpha 1-ACT. Serum levels of alpha 1-ACT along with those of other acute phase proteins were altered in patients with inflammation. This investigation showed that in I-AD patients with increased alpha 1-ACT and no concomitant elevation of other acute phase proteins, serum levels of alpha 1-ACT varied with time. Based on our results, serum alpha 1-ACT does not appear to be a useful biomarker for clinical diagnosis of probable I-AD, but it might be associated with the clinical history of the disease.     

Child health policy: Next steps for psychology.

Indicates that developments within pediatric psychology and health psychology, as well as increased focus on prevention in psychology and allied health fields, have enhanced the engagement of psychologists in the child and adolescent health care field. Psychologists committed to the promotion of children's health should look toward a broader social context and identify organizational arrangements that will achieve a better integration of mental and general health care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultra-miniature coupled resonator filter with single-layer acoustic coupler

Coupled resonator filters designed using a singlelayer coupler require coupling materials with an acoustic impedance less than 5.0 MRayl. Carbon-doped oxide, with an acoustic impedance of 4.8 MRayl and an acoustic attenuation of 200 to 600 dB/cm at 1 GHz, can be used as a single-layer coupler to produce a competitive 2-stage coupled resonator filter for cellular handset applications in the gigahertz frequency range. The electrical response of our filter is superior to that of coupled resonator filters using a traditional acoustic mirror as the coupling element. We present an ultra-miniature 0.58 mm x 0.38 mm coupled resonator filter operating at a frequency of 2.15 GHz.     

The chemo-protector effects of tea and its components

Tea has been consumed worldwide since ancient times to maintain and improve health. Its main active components are a type of polyphenols known as flavonoids, which include catechins and theaflavins. Several epidemiological studies suggest that the consumption of green tea could prevent cancer development in humans. Likewise, animal studies have shown that green tea consumption may inhibit the development of prostate and breast cancer. It has been shown that, through several mechanisms, tea polyphenols present antioxidant and anticarcinogenic activities, thus affording several health benefits. It is important to better characterize tea components, to study their bio-availability and bio-transformation in vivo and to conduct clinical studies of its main active compounds.     

Anisotropic pure-phase plates for quality improvement of partially coherent,partially polarized beams

From a theoretical point of view, the use of anisotropic pure-phase plates (APP) is considered in order to improve the quality parameter of certain partially coherent, partially polarized beams. It is shown that, to optimize the beam-quality parameter, the phases of the two Cartesian components of the field at the output of the APP plate should be identical and should exhibit a quadratic dependence on the radial polar coordinate.     

Bioconversion of poly(vinyl alcohol) to vanillin in a <Emphasis Type="Italic">Phanerochaete chrysosporum</Emphasis> culture medium

The bioconversion of Phanerochaete chrysosporium cultures in aqueous poly(vinyl alcohol) – PVAL – solutions was studied. A 50% weight loss was observed within 20 days, caused by a ligninperoxidase – LiP – enzyme which is produced during the secondary metabolism of Phanerochaete chrysosporium. The changes of the chemical structure of PVAL were studied by UV- and IR-spectroscopy. The presence of vanillin – the major metabolic reaction product, benzaldehyde, and veratrylalcohol was determined chromatographically (HPLC) in the extra cellular medium after different reaction times. A possible mechanism of the biological degradation is outlined.     

Fabrication and modeling of uniform-waist single-mode tapered optical fiber sensors

We report the fabrication and modeling of single-mode tapered optical fiber sensors. The fabrication technique consist of stretching a section of fiber with an oscillating flame torch. Such a process allows controllable fabrication of lossless tapered fibers with a uniform waist. The sensor transmittance is modeled with a simple ray optics approach. In the model, all the taper parameters are taken into account. Our results indicate that sensor sensitivity can be adjusted with the taper waist diameter. As an example a gold-coated tapered fiber is theoretically and experimentally analyzed.