In situ interface engineering for probing the limit of quantum dot photovoltaic devices.

Quantum dot (QD) photovoltaic devices are attractive for their low-cost synthesis, tunable band gap and potentially high power conversion efficiency (PCE). However, the experimentally achieved efficiency to date remains far from ideal. Here, we report an in-situ fabrication and investigation of single TiO2-nanowire/CdSe-QD heterojunction solar cell (QDHSC) using a custom-designed photoelectric transmission electron microscope (TEM) holder. A mobile counter electrode is used to precisely tune the interface area for in situ photoelectrical measurements, which reveals a strong interface area dependent PCE. Theoretical simulations show that the simplified single nanowire solar cell structure can minimize the interface area and associated charge scattering to enable an efficient charge collection. Additionally, the optical antenna effect of nanowire-based QDHSCs can further enhance the absorption and boost the PCE. This study establishes a robust 'nanolab' platform in a TEM for in situ photoelectrical studies and provides valuable insight into the interfacial effects in nanoscale solar cells

Minimising barriers to dental care in older people

<p>Abstract</p> <p>Background</p> <p>Older people are increasingly retaining their natural teeth but at higher risk of oral disease with resultant impact on their quality of life. Socially deprived people are more at risk of oral disease and yet less likely to take up care. Health organisations in England and Wales are exploring new ways to commission and provide dental care services in general and for vulnerable groups in particular. This study was undertaken to investigate barriers to dental care perceived by older people in socially deprived inner city area where uptake of care was low and identify methods for minimising barriers in older people in support of oral health.</p> <p>Methods</p> <p>A qualitative dual-methodological approach, utilising both focus groups and individual interviews, was used in this research. Participants, older people and carers of older people, were recruited using purposive sampling through day centres and community groups in the inner city boroughs of Lambeth, Southwark and Lewisham in South London. A topic guide was utilised to guide qualitative data collection. Informants' views were recorded on tape and in field notes. The data were transcribed and analysed using Framework Methodology.</p> <p>Results</p> <p>Thirty-nine older people and/or their carers participated in focus groups. Active barriers to dental care in older people fell into five main categories: cost, fear, availability, accessibility and characteristics of the dentist. Lack of perception of a need for dental care was a common 'passive barrier' amongst denture wearers in particular. The cost of dental treatment, fear of care and perceived availability of dental services emerged to influence significantly dental attendance. Minimising barriers involves three levels of action to be taken: individual actions (such as persistence in finding available care following identification of need), system changes (including reducing costs, improving information, ensuring appropriate timing and location of care, and good patient management) and societal issues (such as reducing isolation and loneliness). Older people appeared to place greater significance on system and societal change than personal action.</p> <p>Conclusion</p> <p>Older people living within the community in an inner city area where NHS dental care is available face barriers to dental care. Improving access to care involves actions at individual, societal and system level. The latter includes appropriate management of older people by clinicians, policy change to address NHS charges; consideration of when, where and how dental care is provided; and clear information for older people and their carers on available local dental services, dental charges and care pathways.</p

How to calculate the dose of chemotherapy

Body surface area-dosing does not account for the complex processes of cytotoxic drug elimination. This leads to an unpredictable variation in effect. Overdosing is easily recognised but it is possible that unrecognised underdosing is more common and may occur in 30% or more of patients receiving standard regimen. Those patients who are inadvertently underdosed are at risk of a significantly reduced anticancer effect. Using published data, it can be calculated that there is an almost 20% relative reduction in survival for women receiving adjuvant chemotherapy for breast cancer as a result of unrecognised underdosing. Similarly, the cure rate of cisplatin-based chemotherapy for advanced testicular cancer may be reduced by as much as 10%. The inaccuracy of body surface area-dosing is more than an inconvenience and it is important that methods for more accurate dose calculation are determined, based on the known drug elimination processes for cytotoxic chemotherapy. Twelve rules for dose calculation of chemotherapy are given that can be used as a guideline until better dose-calculation methods become available. Consideration should be given to using fixed dose guidelines independent of body surface area and based on drug elimination capability, both as a starting dose and for dose adjustment, which may have accuracy, safety and financial advantages

3D nanoscale analysis of zeolite catalysts by electron tomography and image processing

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Multiple-signaling pathways are involved in the inhibitory effects of galangin on urinary bladder contractility

Aims: Flavonoids comprise a large group of natural polyphenolic compounds, which possess a wide spectrum of physiological and pharmacological effects. Recently, the flavonoid galangin was found to modulate smooth muscle contractility. The aim of the present study was to investigate the mechanism of actions of galangin on pig bladder smooth muscle and to characterize its potential as an alternative inhibitor of bladder smooth muscle contraction. Materials and Methods: Strips of pig detrusor muscle were mounted in separate 6-ml organ baths containing Krebs solution. The contractile response to carbachol (10(-8)- 10(-4) M), potassium (2 X 10(-2) -10(-1)M), and electrical field stimulation-EFS (2-32 Hz) were determined before and after the addition of galangin (3 X 10(-5) M). The contractile responses to carbachol in calcium-free Krebs' solution plus EGTA and L-type channel blocker were determined in the absence and presence of the flavonoid. Furthermore, the effect of galangin was also evaluated after the administration in the bath of a number of antagonists/inhibitors including a combination of propranolol, phentolamine, capsazepine, and verapamil. Student's t-test and one factor ANOVA were used to determine the statistical significance of the effects. Results: Galangin inhibited the maximal contractile response to carbachol and potassium by 57.41% (P 0.05), respectively. The inhibitory effect of galangin was unaffected by a combination of propranolol, phentolamine, and capsazepine (P > 0.05). However, when verapamil was added to the medium, the inhibitory effects of galangin were partially blocked. Conclusions: Galangin, at high concentrations, exerts an inhibitory effect on pig bladder smooth muscle contractility through the inhibition of calcium influx and the modulation of intracellular calcium movement. Furthermore, we have demonstrated that the inhibitory effect of galangin involves, at least in part, L-type calcium channels pathways. Neurourol. Urodynam. 24369-373, 2005. (c) 2005 Wiley-Liss, Inc.24436937

From qualitative to quantitative understanding of support effects on the selectivity in silver catalyzed ethylene epoxidation

\u3cp\u3e In the epoxidation of ethylene, catalyzed by supported Ag particles, the support plays not only a beneficial role, but can also negatively impact the selectivity to ethylene oxide. Especially high surface area supports, and supports containing acid groups, seem detrimental for the selectivity, which is attributed to secondary reactions on the support surface. We prepared Ag nanoparticles on supports with a wide range of specific surface areas and different chemical nature, but with similar Ag metal loading and particle size. Indeed, a strong dependence of selectivity on both the specific surface area, and the chemical nature of the oxide support was found, with α-Al \u3csub\u3e2\u3c/sub\u3e O \u3csub\u3e3\u3c/sub\u3e giving much more selective catalysts than SiO \u3csub\u3e2\u3c/sub\u3e . Furthermore, the conversion was an important factor in determining the selectivity, while on the other hand the support had no influence at all on the ethylene conversion. We described our experimental selectivities with a reaction model that used the rate constant for the secondary reaction of oxidation of ethylene oxide to carbon dioxide and water as the only variable parameter. The model was able to adequately describe the experimental results. It gave insight into the dependence of selectivity on conversion, how the secondary reaction depended on the chemical nature of the support, and how its rate scaled linearly with the support's specific surface area. Building on this insight we modified a SiO \u3csub\u3e2\u3c/sub\u3e support to passivate its OH-groups, which indeed yielded a 94% decrease in the rate of the secondary reaction, performing even better than α-Al \u3csub\u3e2\u3c/sub\u3e O \u3csub\u3e3\u3c/sub\u3e with similar specific surface area would. We have shown that the selectivity towards ethylene oxide is dependent on a metal specific, intrinsic selectivity, and the decrease in selectivity with conversion to be support dependent. This decrease is caused by the isomerization of ethylene oxide, which is found to be first order in ethylene oxide and the active sites on the catalyst support. \u3c/p\u3