High optical efficiency of ZnO nanoparticles

We develop optically efficient photocatalytic ZnO nanoparticles that we chemically embed and well disperse into host PVAc thin films and experimentally demonstrate the highest optical efficiency of ∼70% in ZnO nanoparticle films, with increasing optical spectral efficiency as the excitation wavelength is swept from 370 nm to 290 nm. ©2007 Optical Society of America

Size effect in optical activation of TiO2 nanoparticles in photocatalytic process

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Comparative study of optically activated nanocomposites with photocatalytic TiO2 and ZnO nanoparticles for massive environmental decontamination

Nanocomposites that incorporate TiO2 and ZnO nanoparticles separately in three-dimensional solgel matrices through full chemical integration are prepared to perform highly efficient photocatalytic activities for applications of environmental decontamination. Spectral responses of photocatalytic TiO2 and ZnO nanoparticles exposed to UV activation for self-cleaning process were obtained as also their optical relative spectral efficiency curves from 270 to 370 nm in the UV regime. Our investigations of the optimal conditions to increase their spectral photocatalytic efficiencies resulted in remarkably high levels of optical recovery and efficiency

Killing by type VI secretion drives genetic phase separation and correlates with increased cooperation

By nature of their small size, dense growth and frequent need for extracellular metabolism, microbes face persistent public goods dilemmas. Genetic assortment is the only general solution stabilizing cooperation, but all known mechanisms structuring microbial populations depend on the availability of free space, an often unrealistic constraint. Here we describe a class of self-organization that operates within densely packed bacterial populations. Through mathematical modelling and experiments with Vibrio cholerae, we show how killing adjacent competitors via the Type VI secretion system (T6SS) precipitates phase separation via the ‘Model A' universality class of order-disorder transition mediated by killing. We mathematically demonstrate that T6SS-mediated killing should favour the evolution of public goods cooperation, and empirically support this prediction using a phylogenetic comparative analysis. This work illustrates the twin role played by the T6SS, dealing death to local competitors while simultaneously creating conditions potentially favouring the evolution of cooperation with kin

The Effect Of Acute Normovolemic Hemodilution And Acute Hypervolemic Hemodilution On Coagulation And Allogeneic Transfusion

Objective: In this study, acute normovolemic hemodilution (ANH) and hypervolemic hemodilution (HHD) were compared with no hemodilution with regards to the effectiveness in blood usage and coagulation parameters. Methods: The study was performed from February to August 2001 at Hacettepe University Hospital, Ankara, Turkey. Thirty patients undergoing hip arthroplasty surgery were prospectively randomized into: ANH group [autologous blood 15 mL kg(-1) was withdrawn and replaced by 6% hydroxyethyl starch (HES)] or HHD group (HES was administered without removal of any autologous blood) or the control group (no hemodilution). In all groups, blood was given when hemoglobin concentration was <9 g dl(-1). Results: Three groups were clinically similar regarding blood loss, mean arterial pressures and coagulation parameters. But allogeneic transfusion requirements were significantly less in hemodilution groups (20% in ANH, 40% in HHD) compared to the control group (100% of patients). Conclusion: We conclude that hemodilution (both ANH and HHD) decreases the demand for homologous blood without adversely affecting hemodynamics or coagulation parameters and HHD seems to be a simple and valuable alternative to ANH in orthopedic patient undergoing hip replacement.Wo

Effects Of Low And High Intra-Abdominal Pressure On Immune Response In Laparoscopic Cholecystectomy

Objective: Immunosuppression is directly related to the degree of trauma. The aim of this study is to compare the effects of low and high intra-abdominal pressure on immune response in moderate surgical trauma. Methods: Twenty-two patients, scheduled for laparoscopic cholecystectomy, were randomly allocated to one of 2 groups according to intra-abdominal pressure: low and high intra-abdominal pressure. This study was conducted in the Hacettepe University Faculty of Medicine, Operation Room, Ankara, Turkey. Serum interleukin (IL)-2 and IL-6 levels were measured. Results: Serum IL-2 showed a significant decrease before the incision in high intra-abdominal pressure group. The increase in serum IL-6 at the end of surgery and postoperatively was lower in low intra-abdominal pressure group. Conclusion: These results, can be interpreted as the immune system, are less depressed when there is lower intra-abdominal pressure. This may have clinical implications in immunocompromised patients.Wo

Photocatalytic hybrid nanocomposites of metal oxide nanoparticles enhanced towards the visible spectral range

Cataloged from PDF version of article.We propose and demonstrate photocatalytic hybrid nanocomposites that co-integrate TiO(2) and ZnO nanoparticles in the same host resin to substantially enhance their combined photocatalytic activity in the near-UV and visible spectral ranges, where the intrinsic photocatalytic activity of TiO2 nanoparticles or that of ZnO nanoparticles is individually considerably weak For a comparative study, by embedding TiO(2) nanoparticles of ca. 6 nm and ZnO nanoparticles of ca. 40 nm in the sol-gel matrix of acrylic resin, we make thin film coatings of TiO(2)-ZnO nanoparticles (combination of TiO2 and ZnO, each with a mass ratio of 8.5%), as well as the composite films of TiO(2) nanoparticles alone (17.0%), and ZnO nanoparticles alone (17.0%), and a negative control group with no nanoparticles. For all of these thin films coated on polyvinyl chloride (PVC) polyester, we experimentally study photocatalytic activity and systematically measure spectral degradation (recovery obtained by photocatalytic reactions). This spectral characterization exhibits photodegradation levels of the contaminant at different excitation wavelengths (in the range of 310-469 nm) to distinguish different parts of optical spectrum where TiO(2) and ZnO nanopartides are individually and concurrently active. We observe that the photocatalytic activity is significantly improved towards the visible range with the use of TiO(2)-ZnO combination compared to the individual cases. Particularly for the excitation wavelengths of photochemical reactions longer than 400 nm, where the negative control group and ZnO nanoparticles alone yield no observable photodegradation level and TiO2 nanoparticles alone lead to a low photodegradation level of 14%, the synergic combination of TiO(2)-ZnO nanoparticles achieves a photodegradation level as high as 30%. Investigating their scanning electron microscopy (SEM), X-ray diffraction (XRD), and high resolution transmission electron microscopy (HRTEM), we present evidence of the heterostructure, crystallography, and chemical bonding states for the hybrid TiO(2)-ZnO nanocomposite films, in comparison to the films of only TiO(2) nanoparticles, only ZnO nanoparticles, and no nanoparticles. (C) 2011 Elsevier B.V. All rights reserved