Variance decomposition: a tool enabling strategic improvement of the precision of analytical recovery and concentration estimates associated with microorganism enumeration methods.

Concentrations of particular types of microorganisms are commonly measured in various waters, yet the accuracy and precision of reported microorganism concentration values are often questioned due to the imperfect analytical recovery of quantitative microbiological methods and the considerable variation among fully replicated measurements. The random error in analytical recovery estimates and unbiased concentration estimates may be attributable to several sources, and knowing the relative contribution from each source can facilitate strategic design of experiments to yield more precise data or provide an acceptable level of information with fewer data. Herein, variance decomposition using the law of total variance is applied to previously published probabilistic models to explore the relative contributions of various sources of random error and to develop tools to aid experimental design. This work focuses upon enumeration-based methods with imperfect analytical recovery (such as enumeration of Cryptosporidium oocysts), but the results also yield insights about plating methods and microbial methods in general. Using two hypothetical analytical recovery profiles, the variance decomposition method is used to explore 1) the design of an experiment to quantify variation in analytical recovery (including the size and precision of seeding suspensions and the number of samples), and 2) the design of an experiment to estimate a single microorganism concentration (including sample volume, effects of improving analytical recovery, and replication). In one illustrative example, a strategically designed analytical recovery experiment with 6 seeded samples would provide as much information as an alternative experiment with 15 seeded samples. Several examples of diminishing returns are illustrated to show that efforts to reduce error in analytical recovery and concentration estimates can have negligible effect if they are directed at trivial error sources.

Molecular assessment of heterotrophy and prey digestion in zooxanthellate cnidarians.

Zooxanthellate cnidarians are trophically complex, relying on both autotrophy and heterotrophy. Although several aspects of heterotrophy have been studied in these organisms, information linking prey capture with digestion is still missing. We used prey-specific PCR-based tools to assess feeding and prey digestion of two zooxanthellate cnidarians - the tropical sea anemone Aiptasia sp. and the scleractinian coral Oculina arbuscula. Prey DNA disappeared rapidly for the initial 1-3 days, whereas complete digestion of prey DNA required up to 10 days in O. arbuscula and 5 or 6 days in Aiptasia sp. depending on prey species. These digestion times are considerably longer than previously reported from microscopy-based examination of zooxanthellate cnidarians and prey DNA breakdown in other marine invertebrates, but similar to prey DNA breakdown reported from terrestrial invertebrates such as heteroptera and spiders. Deprivation of external prey induced increased digestion rates during the first days after feeding in O. arbuscula, but after 6 days of digestion, there were no differences in the remaining prey levels in fed and unfed corals. This study indicates that prey digestion by symbiotic corals may be slower than previously reported and varies with the type of prey, the cnidarian species and its feeding history. These observations have important implications for bioenergetic and trophodynamic studies on zooxanthellate cnidarians.

Analytical recovery of protozoan enumeration methods: have drinking water QMRA models corrected or created bias?

Quantitative microbial risk assessment (QMRA) is a tool to evaluate the potential implications of pathogens in a water supply or other media and is of increasing interest to regulators. In the case of potentially pathogenic protozoa (e.g. Cryptosporidium oocysts and Giardia cysts), it is well known that the methods used to enumerate (oo)cysts in samples of water and other media can have low and highly variable analytical recovery. In these applications, QMRA has evolved from ignoring analytical recovery to addressing it in point-estimates of risk, and then to addressing variation of analytical recovery in Monte Carlo risk assessments. Often, variation of analytical recovery is addressed in exposure assessment by dividing concentration values that were obtained without consideration of analytical recovery by random beta-distributed recovery values. A simple mathematical proof is provided to demonstrate that this conventional approach to address non-constant analytical recovery in drinking water QMRA will lead to overestimation of mean pathogen concentrations. The bias, which can exceed an order of magnitude, is greatest when low analytical recovery values are common. A simulated dataset is analyzed using a diverse set of approaches to obtain distributions representing temporal variation in the oocyst concentration, and mean annual risk is then computed from each concentration distribution using a simple risk model. This illustrative example demonstrates that the bias associated with mishandling non-constant analytical recovery and non-detect samples can cause drinking water systems to be erroneously classified as surpassing risk thresholds.

Acupuncturist perceptions of serving as a clinical trial practitioner.

OBJECTIVE: This article describes the experience of four acupuncturists in terms of what it meant for them to be a practitioner in a recently completed sham-controlled acupuncture randomized control trial (RCT) with a standardized protocol. DESIGN: At the completion of the RCT for women with ovarian dysfunction, study acupuncturists (2 male MD/acupuncturists and 2 female professional acupuncturists) were queried about their perceptions of participating in the RCT using both written responses to 5 open-ended questions and a focus group interview. Data was analyzed to categorize responses and identify themes. SETTING: Virginia, USA. RESULTS: The acupuncturists' experience of participating in a RCT was generally very positive, including: usual practitioner/participant relationships, collegial sharing, and increased patient volume and diversity. There was angst expressed about the unknown RCT results. While there were concerns about standardizing the acupuncture session ("dilutes the power of acupuncture therapeutics"), the acupuncturists' were supportive of the pre-established protocol. The acupuncturists overall did not have concerns with a sham intervention arm because the sham recipients did not know their treatment arm and felt as satisfied with study participation as the true acupuncture recipients. CONCLUSIONS: Despite initial misgivings about both a standardized protocol and a sham arm, all practitioners discovered positive aspects of being a study acupuncturist. The analysis highlights the need for communication before, during and after a clinical trial between the study investigators and the intervention practitioners. As stake holders in the perception of CAM therapies with the public and with conventional medicine practitioners, it would benefit future research on CAM to similarly assess experiences of being a CAM study practitioner in order to enhance provider recruitment and reduce provider drop-out.

Psychometric value of the Center for Epidemiologic Studies Depression (CES-D) scale for screening of depressive symptoms in Armenian population.

BACKGROUND: This study examined the psychometric value of the Center for Epidemiologic Studies Depression Scale (CES-D) translated for use with an Armenian population. METHODS: Using data obtained from a country-wide health survey of 2310 households involving female and male respondents aged 18 and over, we investigated the response pattern to the CES-D items, the factor structure, internal consistency, inter-item correlations of the total scale and its negatively and positively formulated subscales. We used logistic regression analysis to relate the constructs measured by the CES-D and its subscales to known determinants of depression. RESULTS: Armenian respondents of both genders significantly suppressed their positive emotions, thus over-endorsing positively formulated (reverse-coded) items, therefore producing artificially high depression scores. Factor analysis of the scale yielded a three-factor structure (combined Depressed/Somatic, Positive Affect, and Interpersonal). The Positive Affect factor correlated weakly with the other two factors, and its inclusion reduced the internal consistency of the whole scale. Unlike the 16-item subscale of negatively formulated items, Positive Affect was not related to several known determinants of depression and did not reflect known depression-specific differences between genders. The set of determinants of Positive Affect included mainly lifestyle and attitudinal variables. LIMITATIONS: This study did not assess the concurrent and discriminate validity of the Armenian CES-D. CONCLUSIONS: For Armenians, the construct measured by the four Positive Affect items of CES-D is not related to depressive symptoms as measured by the other items. It introduces ethnical/cultural response bias in CES-D score and reduces the cross-cultural comparability of the latter.

The reliability and predictive validity of the Heaviness of Smoking Index and its two components: findings from the International Tobacco Control Four Country study.

BACKGROUND: There is increasing recognition that the two measures in the Heaviness of Smoking Index (HSI), time to first cigarette of the day (TTFC) and daily consumption (cigarettes per day [CPD]), are strong predictors of quitting behavior. METHODS: Use of Waves 1-4 of International Tobacco Control cohort with around 8,000 respondents per wave and 6,000 for prediction of quit outcomes at the next wave. We measured TTFC and CPD at each wave and quit outcomes at the next wave. We also looked at the relative utility of the standard categorical scoring compared with a continuous score using the square root of CPD minus the natural log of TTFC in minutes. RESULTS: We found considerable consistency of the measures across years with a small decrease as duration between measurements increased. For a 3-year gap, the correlations were .72 and .70 for the continuous and categorical composite HSI measures, respectively, and were at least .63 for the individual components. Both TTFC and CPD independently predicted maintenance of quit attempts (for at least 1 month) in each of the three wave-to-wave replications, and these effects were maintained when controlling for demographic factors. CPD also predicted making attempts consistently, but the results for TTFC was not consistently significant. DISCUSSION: Both TTFC and CPD are fairly reliable over time and are important predictors of quitting. There are only small effects of mode of computing the scores, and the two items can be used either individually or combined as the HSI.

Reported awareness of tobacco advertising and promotion in China compared to Thailand, Australia and the USA.

BACKGROUND: China currently does not have comprehensive laws or regulations on tobacco advertising and promotion, although it ratified the World Health Organization (WHO) Framework Convention on Tobacco Control (FCTC) in October 2005 and promised to ban all tobacco advertising by January 2011. Much effort is needed to monitor the current situation of tobacco advertising and promotion in China. OBJECTIVE: This study aims to examine levels of awareness of tobacco advertising and promotion among smokers in China as compared to other countries with different levels of restrictions. METHODS: One developing country (Thailand) and two developed countries (Australia and the USA) were selected for comparison. All four countries are part of the International Tobacco Control (ITC) Policy Evaluation Survey project. Between 2005 and 2006, parallel ITC surveys were conducted among adult smokers (at least smoked weekly) in China (n = 4763), Thailand (n = 2000), Australia (n = 1767) and the USA (n = 1780). Unprompted and prompted recall of noticing tobacco advertising and promotion were measured. RESULTS: Chinese respondents reported noticing tobacco advertisements in a range of channels and venues, with highest exposure levels on television (34.5%), billboards (33.4%) and in stores (29.2%). A quarter of respondents noticed tobacco sponsorships, and a high level of awareness of promotion was reported. Cross-country comparison reveals that overall reported awareness was significantly higher in China than in Thailand (particularly) and Australia, but lower than in the USA. CONCLUSIONS: There is a big gap between China and the better-performing countries such as Thailand and Australia regarding tobacco promotion restrictions. China needs to do more, including enhanced policy and more robust enforcement.

Characterization of melamine-containing and calcium oxalate crystals in three dogs with suspected pet food-induced nephrotoxicosis.

The histomorphologic characteristics and chemical composition of the crystals associated with suspected pet food-induced nephrotoxicosis in 3 dogs are described. Kidney specimens from 2 dogs, a 3-year-old Parson Russell Terrier and a 3-year-old Bernese Mountain Dog, were examined. Both developed acute renal failure after eating canned pet food on the 2007 Menu Foods recall list. The third case was a kidney specimen from a 1-year-old mixed-breed dog from a similar 2004 outbreak of canine renal failure in Taiwan, which occurred after eating a commercial dog food. Hematoxylin and eosin (HE), 72-hour Oil Red O (ORO72h), Alizarin Red S (pH 4.1-4.3), and Von Kossa stains; infrared (IR) spectroscopy; and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDXA) were performed to determine the histomorphologic characteristics and chemical composition of the crystals observed in each case. Histomorphologic findings in each case included acute, marked tubular degeneration and necrosis with many intratubular birefringent crystals, and lymphoplasmacytic interstitial nephritis. In each case, most of the crystals were rough, pale brown, and stained with ORO72h but did not stain with Alizarin Red S (pH 4.1-4.3) or Von Kossa stains; these features were consistent with a plastic or lipid. IR spectroscopy and SEM/EDXA results were consistent with melamine-containing crystals. A second crystal type identified in each case was smooth and platelike with staining characteristics and IR spectroscopy and SEM/EDXA results consistent with calcium oxalate crystals. Melamine-containing crystals have distinct light microscopic, histochemical, and SEM/EDXA characteristics that facilitate their identification in tissue.

Reactive arthritis following culture-confirmed infections with bacterial enteric pathogens in Minnesota and Oregon: a population-based study.

OBJECTIVE: To describe the epidemiology and clinical spectrum of reactive arthritis (ReA) following culture-confirmed infection with bacterial enteric pathogens in a population-based study in the USA. METHODS: We conducted telephone interviews of persons age>1 year with culture confirmed Campylobacter, Escherichia coli O157, Salmonella, Shigella and Yersinia infections reported to FoodNet (http://www.cdc.gov/FoodNet/) in Minnesota, USA and Oregon, USA between 2002 and 2004. SUBJECTS: with new onset joint pain, joint swelling, back pain, heel pain and morning stiffness lasting >or=3 days within 8 weeks of culture (possible ReA) were invited to complete a detailed questionnaire and physical examination. RESULTS: A total of 6379 culture-confirmed infections were reported; 70% completed screening interviews. Of these, 575 (13%) developed possible ReA; incidence was highest following Campylobacter (2.1/100,000) and Salmonella (1.4/100,000) infections. Risk was greater for females (relative risk (RR) 1.5, 95% CI, 1.3 to 1.7), adults (RR 2.5, 95% CI, 2.0 to 3.1) and subjects with severe acute illness (eg, fever, chills, headache, persistent diarrhoea). Risk was not associated with antibiotic use or human leukocyte antigen (HLA)-B27. A total of 54 (66%) of 82 subjects examined had confirmed ReA. Enthesitis was the most frequent finding; arthritis was less common. The estimated incidence of ReA following culture-confirmed Campylobacter, E coli O157, Salmonella, Shigella and Yersinia infections in Oregon was 0.6-3.1 cases/100,000. CONCLUSIONS: This is the first population-based study of ReA following infections due to bacterial enteric pathogens in the USA. These data will help determine the burden of illness due to these pathogens and inform clinicians about potential sequelae of these infections.

Methods of the International Tobacco Control (ITC) Four Country Survey.

This paper outlines the design features, data collection methods and analytic strategies of the International Tobacco Control (ITC) Four Country Survey, a prospective study of more than 2000 longitudinal respondents per country with yearly replenishments. This survey possesses unique features that sets it apart among surveys on tobacco use and cessation. One of these features is the use of theory-driven conceptual models. In this paper, however, the focus is on the two key statistical features of the survey: longitudinal and "quasi-experimental" designs. Although it is often possible to address the same scientific questions with a cross-sectional or a longitudinal study, the latter has the major advantage of being able to distinguish changes over time within individuals from differences among people at baseline (that is, differences between age and cohort effects). Furthermore, quasi-experiments, where countries not implementing a given new tobacco control policy act as the control group to which the country implementing such a policy will be compared, provide much stronger evidence than observational studies on the effects of national-level tobacco control policies. In summary, application of rigorous research methods enables this survey to be a rich data resource, not only to evaluate policies, but also to gain new insights into the natural history of smoking cessation, through longitudinal analyses of smoker behaviour.

The conceptual framework of the International Tobacco Control (ITC) Policy Evaluation Project.

This paper describes the conceptual model that underlies the International Tobacco Control Policy Evaluation Project (ITC Project), whose mission is to measure the psychosocial and behavioural impact of key policies of the Framework Convention on Tobacco Control (FCTC) among adult smokers, and in some countries, among adult non-smokers and among youth. The evaluation framework utilises multiple country controls, a longitudinal design, and a pre-specified, theory-driven conceptual model to test hypotheses about the anticipated effects of specific policies. The ITC Project consists of parallel prospective cohort surveys of representative samples of adult smokers currently in nine countries (inhabited by over 45% of the world's smokers), with other countries being added in the future. Collectively, the ITC Surveys constitute the first-ever international cohort study of tobacco use. The conceptual model of the ITC Project draws on the psychosocial and health communication literature and assumes that tobacco control policies influence tobacco related behaviours through a causal chain of psychological events, with some variables more closely related to the policy itself (policy-specific variables) and other variables that are more downstream from the policy, which have been identified by health behaviour and social psychological theories as being important causal precursors of behaviour (psychosocial mediators). We discuss the objectives of the ITC Project and its potential for building the evidence base for the FCTC.

Reductions in tobacco smoke pollution and increases in support for smoke-free public places following the implementation of comprehensive smoke-free workplace legislation in the Republic of Ireland: findings from the ITC Ireland/UK Survey.

OBJECTIVE: To evaluate the psychosocial and behavioural impact of the first ever national level comprehensive workplace smoke-free law, implemented in Ireland in March 2004. DESIGN: Quasi-experimental prospective cohort survey: parallel cohort telephone surveys of national representative samples of adult smokers in Ireland (n = 769) and the UK (n = 416), surveyed before the law (December 2003 to January 2004) and 8-9 months after the law (December 2004 to January 2005). MAIN OUTCOME MEASURES: Respondents' reports of smoking in key public venues, support for total bans in those key venues, and behavioural changes due to the law. RESULTS: The Irish law led to dramatic declines in reported smoking in all venues, including workplaces (62% to 14%), restaurants (85% to 3%), and bars/pubs (98% to 5%). Support for total bans among Irish smokers increased in all venues, including workplaces (43% to 67%), restaurants (45% to 77%), and bars/pubs (13% to 46%). Overall, 83% of Irish smokers reported that the smoke-free law was a "good" or "very good" thing. The proportion of Irish homes with smoking bans also increased. Approximately 46% of Irish smokers reported that the law had made them more likely to quit. Among Irish smokers who had quit at post-legislation, 80% reported that the law had helped them quit and 88% reported that the law helped them stay quit. CONCLUSION: The Ireland smoke-free law stands as a positive example of how a population-level policy intervention can achieve its public health goals while achieving a high level of acceptance among smokers. These findings support initiatives in many countries toward implementing smoke-free legislation, particularly those who have ratified the Framework Convention on Tobacco Control, which calls for legislation to reduce tobacco smoke pollution.

Ill-health retirement: national rates and updated guidance for occupational physicians.

BACKGROUND: Advising on ill-health retirement is an important role of most practising occupational physicians. In recent years, the eligibility criteria and process for gaining early retirement benefits have changed in many pension schemes in the UK. AIM: To investigate the variation in rates of retirement due to ill-health in National Health Service (NHS) Trusts and Local Authorities and to update previously published guidance on ill-health retirement with specific reference to pension schemes with eligibility criteria that include permanence of incapacity due to ill-health. METHODS: Rates of retirement were calculated for 222 NHS Trusts and 132 Local Authorities with more than 1500 employees. Literature searches and consensus statements by the authors. RESULTS: Rates of retirement were widely distributed in the NHS Trusts and Local Authorities. The median rates of retirement were 2.11 (IQR 1.37-2.91)/1000 active members and 4.10 (IQR 3.01-6.10)/1000 employees, respectively (P<0.001). Difficulties in the doctor-patient relationship and in ascertaining the true functional ability of some patients were identified. CONCLUSION: There continues to be marked variation in rates of early retirement due to ill-health within and between organizations that warrants further investigation. The general and specific guidance that appears as an appendix in Supplementary data to this paper should help occupational physicians to make equitable recommendations when assessing applications for early retirement benefits and fitness to work.

Allatostatin in ovaries, oviducts, and young embryos in the cockroach Diploptera punctata.

The quantity and localization of -Phe-Gly-Leu-amide allatostatins (-F-G-L-amide AST) was determined by ELISA and immunohistochemistry in ovaries and oviducts and in pre-dorsal closure embryos. AST in the cytoplasm of basal oocytes gradually increased from 4 to 35 fmol/ovary pair from the start (day 2) to the completion of vitellogenesis (day 6), then rapidly increased to 121 fmol/ovary pair during choriogenesis. In oviducts, AST-immunoreactivity was found in nerves to the muscle layer and in epithelial cells. AST-immunoreactivity in oviduct epithelial cells increased during vitellogenesis. A marked increase in quantity of AST in oviduct tissue between completion of chorion formation and immediately after ovulation appears to result from AST released from oocytes as they travel down the oviducts because AST content of newly ovulated eggs was 40% lower than late stage chorionated oocytes, and these oocytes released AST when incubated in saline. AST in embryos, localized in yolk cells, decreased as embryos approached dorsal closure. That this material in ovaries and embryos is AST was confirmed by its ability to inhibit JH synthesis in vitro and identification by MALDI-TOF mass spectrometry of a peptide with a mass corresponding to that of a Diploptera punctata AST. These findings indicate likely novel functions for ASTs: facilitation of ovulation and utilization of yolk.

Highly phosphorescent bis-cyclometalated iridium complexes: synthesis, photophysical characterization, and use in organic light emitting diodes.

The synthesis and photophysical study of a family of cyclometalated iridium(III) complexes are reported. The iridium complexes have two cyclometalated (C(**)N) ligands and a single monoanionic, bidentate ancillary ligand (LX), i.e., C(**)N2Ir(LX). The C(**)N ligands can be any of a wide variety of organometallic ligands. The LX ligands used for this study were all beta-diketonates, with the major emphasis placed on acetylacetonate (acac) complexes. The majority of the C(**)N2Ir(acac) complexes phosphoresce with high quantum efficiencies (solution quantum yields, 0.1-0.6), and microsecond lifetimes (e.g., 1-14 micros). The strongly allowed phosphorescence in these complexes is the result of significant spin-orbit coupling of the Ir center. The lowest energy (emissive) excited state in these C(**)N2Ir(acac) complexes is a mixture of (3)MLCT and (3)(pi-pi) states. By choosing the appropriate C(**)N ligand, C(**)N2Ir(acac) complexes can be prepared which emit in any color from green to red. Simple, systematic changes in the C(**)N ligands, which lead to bathochromic shifts of the free ligands, lead to similar bathochromic shifts in the Ir complexes of the same ligands, consistent with "C(**)N2Ir"-centered emission. Three of the C(**)N2Ir(acac) complexes were used as dopants for organic light emitting diodes (OLEDs). The three Ir complexes, i.e., bis(2-phenylpyridinato-N,C2')iridium(acetylacetonate) [ppy2Ir(acac)], bis(2-phenyl benzothiozolato-N,C2')iridium(acetylacetonate) [bt2Ir(acac)], and bis(2-(2'-benzothienyl)pyridinato-N,C3')iridium(acetylacetonate) [btp2Ir(acac)], were doped into the emissive region of multilayer, vapor-deposited OLEDs. The ppy2Ir(acac)-, bt2Ir(acac)-, and btp2Ir(acac)-based OLEDs give green, yellow, and red electroluminescence, respectively, with very similar current-voltage characteristics. The OLEDs give high external quantum efficiencies, ranging from 6 to 12.3%, with the ppy2Ir(acac) giving the highest efficiency (12.3%, 38 lm/W, >50 Cd/A). The btp2Ir(acac)-based device gives saturated red emission with a quantum efficiency of 6.5% and a luminance efficiency of 2.2 lm/W. These C(**)N2Ir(acac)-doped OLEDs show some of the highest efficiencies reported for organic light emitting diodes. The high efficiencies result from efficient trapping and radiative relaxation of the singlet and triplet excitons formed in the electroluminescent process.

Synthesis and characterization of phosphorescent cyclometalated iridium complexes.

The preparation, photophysics, and solid state structures of octahedral organometallic Ir complexes with several different cyclometalated ligands are reported. IrCl3.nH2O cleanly cyclometalates a number of different compounds (i.e., 2-phenylpyridine, 2-(p-tolyl)pyridine, benzoquinoline, 2-phenylbenzothiazole, 2-(1-naphthyl)benzothiazole, and 2-phenylquinoline), forming the corresponding chloride-bridged dimers, CwedgeN2Ir(mu-Cl)2IrCwedgeN2 (CwedgeNis a cyclometalated ligand) in good yield. These chloride-bridged dimers react with acetyl acetone (acacH) and other bidentate, monoanionic ligands such as picolinic acid (picH) and N-methylsalicylimine (salH), to give monomeric CwedgeN2Ir(LX) complexes (LX = acac, pic, sal). The emission spectra of these complexes are largely governed by the nature of the cyclometalating ligand, leading to lambda(max) values from 510 to 606 nm for the complexes reported here. The strong spin-orbit coupling of iridium mixes the formally forbidden 3MLCT and 3pi-pi* transitions with the allowed 1MLCT, leading to a strong phosphorescence with good quantum efficiencies (0.1-0.4) and room temperature lifetimes in the microsecond regime. The emission spectra of the CwedgeN2Ir(LX) complexes are surprisingly similar to the fac-IrCwedgeN3 complex of the same ligand, even though the structures of the two complexes are markedly different. The crystal structures of two of the CwedgeN2Ir(acac) complexes (i.e., CwedgeN = ppy and tpy) have been determined. Both complexes show cis-C,C', trans-N,N' disposition of the two cyclometalated ligands, similar to the structures reported for other complexes with a "CwedgeN2Ir" fragment. NMR data (1H and 13C) support a similar structure for all of the CwedgeN2Ir(LX) complexes. Close intermolecular contacts in both (ppy)2Ir(acac) and (tpy)2Ir(acac) lead to significantly red shifted emission spectra for crystalline samples of the ppy and tpy complexes relative to their solution spectra.

Poly(p-hydroxystyrene) grafted polystyrene nanospheres: excellent hosts for silver and ruthenium nanoparticles.

A novel approach is described for the preparation of surface functionalized micro- and nanobeads using one pot synthesis by a core-shell method. Monodisperse poly(p-hydroxystyrene) is successfully prepared by grafting the p-acetoxystyrene monomer during the last 30 min of the fabrication of polystyrene bead core by emulsifier-free emulsion polymerization followed by hydrolysis of the acetoxy group by a base. The size of the resulting beads is dictated mostly by the size of the core. Hydroxyl derivatized polystyrene microspheres have been found useful as a high surface area and stable support for anchoring catalytically active silver and ruthenium nanoparticles. The bead formation, surface functionalization, and coating with metal nanoparticles have been studied using scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectrometry, Fourier transform infrared spectrometry, and Auger analysis.