Biomedical subjects
Publications and source records attributed to Paul O'Brien.
We report a simple and rapid aqueous route to crystalline nanoparticles of PbS and CdS using single-source precursors and a conventional household pressure cooker.
For the first time, we describe a simple, room-temperature surfactant-mediated route to inorganic mesocrystals of NH(4)TiOF(3) and their remarkable topotaxial conversion by washing or annealing to TiO(2) as anatase mesocrystals.
A series of N-alkyldithiocarbamato complexes [M(S2CNHR)2] (M=Cd(II), Zn(II); R=C2H5, C4H9, C6H13, C12H25) have been synthesised and characterized. The decomposition of these complexes to sulfates has been investigated, and a mechanism proposed. The structures of [Zn(S2CNHHex)2], [Cd(SO4)2(NC5H5)4)]n and [Cd(SO4)2(NC5H5)2(H2O)2)]n have been determined by X-ray single crystal method. The cadmium complex [Cd(S2CNHC12H25)2] and zinc complex [Zn(S2CNHC6H13)2] were used as single-source precursors to synthesize CdS and ZnS nanoparticles, respectively. The synthesis of CdS nanoparticles was carried under various thermolysis conditions and changes in the shape of derived nanoparticles were studied by transmission electron microscope (TEM).
The Fertility Regulation Group of the Cochrane Collaboration has been assessing the best available evidence on fertility regulation, family size and birth spacing. By the end of 2005, this group had published 32 systematic reviews and 12 protocols; most reviews were on contraception. Because of suboptimal trial quality, firm conclusions could be made in only five reviews. Threats to internal validity in published trials include the absence of description of allocation concealment, intentional exclusion of participants after randomization, failure to use intention-to-treat analyses and lack of treatment blinding. The precision of results has been limited by small sample sizes. The finding that most trials of oral contraceptives were conducted by pharmaceutical companies raises concerns about potential commercial bias. Of necessity, most information about fertility regulation effectiveness and adverse effects comes from observational studies, which vary widely in quality. Systematic reviews of evidence, with an emphasis on randomized controlled trials when available, will continue to improve fertility regulation in the years ahead.
Synthetic schemes yielding monodisperse nanocrystalline particulates in the form of tetrapods, rods, and prisms have been recently discovered. Conditions promoting growth of different shapes of particulates have been defined. However, the rationale for anisotropic growth and the evolution of specific shapes, such as tetrapods, is as yet unknown. On the basis of simple numerical calculations, we suggest that the need to conserve the surface atoms plays a vital role in the growth of nanocrystals in the formation of tetrapods and correctly predicts the size regime in which such structures are obtained.
Facile and reproducible methods for the syntheses of bis(di-iso-propylselenophosphinyl)selenide ((i)Pr2PSe)2Se (1), bis(di-iso-propylselenophosphinyl)diselenide ((i)Pr2PSe)2Se2 (2) and bis(di-phenylselenophosphinyl)selenide (Ph2PSe)2Se (3) is reported.
The reactions of bis(dialkylselenophosphinyl)selenide with a series of metals have been investigated: synthesis of several metal selenophosphinate complexes and their structures are reported.
Aerosol-assisted chemical vapor deposition (AACVD) of Sb[(TePiPr2)2N]3 results in pure hexagonal Sb2Te3 nanoplates between 375 and 475 degrees C on glass substrates, with a potential for enhanced thermoelectric properties for novel nanodevices.
A simple one-pot method has been used to prepare uniform single-crystalline CoP nanowires with a high aspect ratio by the thermal-decomposition reaction of cobalt(II) acetylacetone with long-chain alkylphosphonic acid in the presence of hexadecylamine (HDA) and trioctylphosphine oxide (TOPO) at high temperature. The crystal morphology of the resulting nanowires can be influenced by the ratio of HDA and TOPO.
We report the photorefractive performance of a polymer composite sensitized by CdSe/ZnS core/shell nanoparticles, and also comprising poly(N-vinylcarbazole) and an electro-optic chromophore. The nanoparticles are characterized by absorption and photoluminescence spectroscopy, elemental analysis, transmission electron microscopy, and powder x-ray diffraction. The electro-optic response of the composite is measured independently of the photorefractive effect by transmission ellipsometry. An asymmetric two-beam coupling gain of 30.6+/-0.4 cm(-1) is obtained, confirming photorefractivity. Degenerate four-wave mixing is used to assess photorefractive performance and, at a poling field of 70 V microm(-1), yields a diffraction efficiency of 4.21%+/-0.03%, a holographic contrast of 3.05 x 10(-4)+/-1 x 10(-6), a space-charge rise time of 25+/-2 s, and a sensitivity of 4.7 x 10(-5)+/-4 x 10(-6) cm3 J(-1). These results constitute a significant improvement on the performance of previous nanoparticle-sensitized photorefractive polymer composites.
We report a novel synthesis of luminescent CdS nanorods which, unusually, are predominantly of the cubic phase.
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EuS nanocrystals, with an average diameter of 9 nm, have been synthesized by the photolysis of Na[Eu(S2CEt2)4].3.5H2O; the first quantum confined particles of EuS to be reported.
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Metal-containing granules were isolated from specimens of the barnacle Tetraclita squamosa collected from a metal contaminated site in Hong Kong. The chemical composition, crystallographic and morphological properties of the deposits were analysed by X-ray powder diffraction, electron microscopy, energy dispersive analysis by X-rays and infrared spectroscopy. The most abundant metals were iron, calcium and zinc and the major anion was phosphate. Oxalates, carbonates and sulfur derivates were also found in small amounts. The deposits were amorphous to X-ray and electron diffraction and were approximately spherical in shape with diameters between 100 and 500 nm.
BACKGROUND: We attempted to compare the safety and efficacy of laparoscopic adjustable gastric banding with vertical-banded gastroplasty and gastric bypass. Morbid obesity presents a serious health issue for Western countries, with a rising incidence and a strong association with increased mortality and serious comorbidities, such as diabetes, hyperlipidemia, and cardiovascular disease. Unfortunately, conservative treatment options have proven ineffective. Surgical interventions, such as vertical-banded gastroplasty (stomach stapling), Roux-en-Y gastric bypass, and, more recently, laparoscopic gastric banding have been developed with the aim of providing a laparoscopically placed device that is safe and effective in generating substantial weight loss. METHODS: Electronic databases were systematically searched for references relating to obesity surgery by (1) laparoscopic adjustable gastric banding (LAGB), (2) vertical banded gastroplasty (VBG), and (3) Roux-en-Y gastric bypass (RYGB). RESULTS: Only 6 studies reported comparative results for laparoscopic gastric banding and other surgical procedures. One study reported comparative results for all 3 surgical procedures, and this study was only of moderate quality. In total, 64 studies were found that reported results for LAGB and 57 studies reported results on the comparative procedures. LAGB was associated with a mean short-term mortality rate of approximately 0.05% and an overall median morbidity rate of approximately 11.3%, compared with 0.50% and 23.6% for RYGB, and 0.31% and 25.7% for VBG. Overall, all 3 procedures produced considerable weight loss in patients up to 4 years in the case of LAGB (the maximum follow-up available at the time of the review), and more than 10 years in the case of the comparator procedures. CONCLUSIONS: The Australian Safety and Efficacy Register of New Interventional Procedures-Surgical Review Group concluded that the evidence base was of average quality up to 4 years for LAGB. Laparoscopic gastric banding is safer than VBG and RYGB, in terms of short-term mortality rates. LAGB is effective, at least up to 4 years, as are the comparator procedures. Up to 2 years, LAGB results in less weight loss than RYGB; from 2 to 4 years there is no significant difference between LAGB and RYGB, but the quality of data is only moderate. The long-term efficacy of LAGB remains unproven, and evaluation by randomized controlled trials is recommended to define its merits relative to the comparator procedures.
This Guidance provides information for clinicians providing women with copper-bearing intrauterine devices as long-term contraception. A key to the grades of recommendations, based on levels of evidence, is given at the end of this document. Details of the methods used by the Clinical Effectiveness Unit (CEU) in developing this Guidance and evidence tables summarising the research basis of the recommendations are available on the Faculty website (www.ffprhc.org.uk). Abbreviations (in alphabetical order) used include: acquired immune deficiency syndrome (AIDS); actinomyces-like organisms (ALOs); automated external defibrillator (AED); blood pressure (BP); British National Formulary (BNF); confidence interval (CI); copper-bearing intrauterine contraceptive device (IUD); emergency contraception (EC); Faculty Aid to Continuing Professional Development Topic (FACT); levonorgestrel-releasing intrauterine system (IUS); human immunodeficiency virus (HIV); Medicines and Healthcare products Regulatory Agency (MHRA); non-steroidal antiinflammatory drugs (NSAIDs); odds ratio (OR); pelvic inflammatory disease (PID); relative risk (RR); Royal College of Obstetricians and Gynaecologists (RCOG); Scottish Intercollegiate Guidelines Network (SIGN); sexually transmitted infection (STI); termination of pregnancy (TOP); World Health Organization (WHO); WHO Medical Eligibility Criteria (WHOMEC); WHO Selected Practice Recommendations (WHOSPR).
CdSe quantum dots with polymerisable ligands have been incorporated into polystyrene beads, via a suspension polymerisation reaction, as a first step towards the optical encoding of solid supports for application in solid phase organic chemistry.