947 research outputs found

    Thin film nanocomposite membrane incorporated with polymethyl metharcylate grafted multi-walled carbon nanotubes for gas separation

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    Membrane technology is an appealing alternative to the conventional carbon dioxide (CO2) separation processes due to its design simplicity, energy efficiency and environmentally benign approach. Nanocomposite membrane, especially the thin film nanocomposite (TFN) is a relatively new class of membrane which features good separation performance and practical processing. Yet, the challenge of achieving good dispersion of the nanosized fillers within the polymer matrix remains unsolved. This study investigated on the potential of TFN containing modified multi-walled carbon nanotubes (MWNTs) for gas separation. Mixed acid oxidation, micro-emulsion polymerization and ball milling have been employed to improve the dispersibility of MWNTs. The TFNs were fabricated via interfacial polymerization technique to allow control over the distribution of the fillers. The effects of modification, incorporation scheme and loading of MWNTs on the gas separation performance have been investigated. The results suggested that grafting MWNTs with polymethyl methacrylate (PMMA) allowed good dispersion of the fillers which can be further enhanced by the physical milling to suppress the formation of aggregates. TFN produced by incorporating the milled PMMA-MWNTs (m-PMMA-MWNTs) within the coating layer showed the best separation performance compared to other incorporation scheme. The performance enhancement of the TFN compared to the thin film composite counterpart was endowed by the addition of well-dispersed MWNTs that served as rapid diffusion channels and the formation defect-free skin. The optimum fillers loading is 0.25 g/L which gives TFN with CO2 permeance of 53.5 gas permeation unit (12% increment), CO2/nitrogen selectivity of 61.0 (1% increment) and CO2/methane selectivity of 35.2 (54% increment). TFN embedded with m- PMMA-MWNTs could potentially be used for low pressure carbon capture and storage application with further developmen

    Effectiveness of a denture hygiene intervention programme among institutionalized elders

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    Objectives: To evaluate the effectiveness of a denture hygiene intervention programme in terms of improving denture cleanliness and denture stomatitis. Methods: Residents at seven elderly care homes were invited to participate in a denture hygiene programme. Clinical assessment of denture stomatitis was undertaken and denture cleanliness assessed: (i) qualitatively by the Denture Cleanliness Index ratings and (ii) quantitatively by planimetric assessments of plaque coverage from digital images using Adobe Photoshop®. Individual denture hygiene instruction was provided and denture cleanser (Polident®) supplied. Six weeks later assessments of denture stomatitis and denture cleanliness were undertaken. Results: Fifty-six participants were recruited; most had evidence of denture stomatitis (82.1%, 46) and 62.5% (35) of dentures were classified as ‘very poorly cleaned’. The mean percentage of plaque coverage was 28.11 (SD 19.64) and 37.5% (21) had evidence of plaque covering more than a third of the denture surface. Denture cleanliness was associated with denture stomatitis (P0.05).Conclusion: A 6-week denture hygiene intervention programme was effective at improving denture stomatitis and denture cleanliness among residents of elderly care homes. However, persistence of problems in denture cleanliness and denture stomatitis existed and this warrants further consideration.published_or_final_versio

    Effectiveness of a denture hygiene intervention programme among institutionalized elders

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    Objectives: To evaluate the effectiveness of a denture hygiene intervention programme in terms of improving denture cleanliness and denture stomatitis. Methods: Residents at seven elderly care homes were invited to participate in a denture hygiene programme. Clinical assessment of denture stomatitis was undertaken and denture cleanliness assessed: (i) qualitatively by the Denture Cleanliness Index ratings and (ii) quantitatively by planimetric assessments of plaque coverage from digital images using Adobe Photoshop®. Individual denture hygiene instruction was provided and denture cleanser (Polident®) supplied. Six weeks later assessments of denture stomatitis and denture cleanliness were undertaken. Results: Fifty-six participants were recruited; most had evidence of denture stomatitis (82.1%, 46) and 62.5% (35) of dentures were classified as ‘very poorly cleaned’. The mean percentage of plaque coverage was 28.11 (SD 19.64) and 37.5% (21) had evidence of plaque covering more than a third of the denture surface. Denture cleanliness was associated with denture stomatitis (P0.05).Conclusion: A 6-week denture hygiene intervention programme was effective at improving denture stomatitis and denture cleanliness among residents of elderly care homes. However, persistence of problems in denture cleanliness and denture stomatitis existed and this warrants further consideration.published_or_final_versio

    Age, period, and cohort analysis of regular dental care behavior and edentulism: A marginal approach

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    <p>Abstract</p> <p>Background</p> <p>To analyze the regular dental care behavior and prevalence of edentulism in adult Danes, reported in sequential cross-sectional oral health surveys by the application of a marginal approach to consider the possible clustering effect of birth cohorts.</p> <p>Methods</p> <p>Data from four sequential cross-sectional surveys of non-institutionalized Danes conducted from 1975-2005 comprising 4330 respondents aged 15+ years in 9 birth cohorts were analyzed. The key study variables were seeking dental care on an annual basis (ADC) and edentulism. For the analysis of ADC, survey year, age, gender, socio-economic status (SES) group, denture-wearing, and school dental care (SDC) during childhood were considered. For the analysis of edentulism, only respondents aged 35+ years were included. Survey year, age, gender, SES group, ADC, and SDC during childhood were considered as the independent factors. To take into account the clustering effect of birth cohorts, marginal logistic regressions with an independent correlation structure in generalized estimating equations (GEE) were carried out, with PROC GENMOD in SAS software.</p> <p>Results</p> <p>The overall proportion of people seeking ADC increased from 58.8% in 1975 to 86.7% in 2005, while for respondents aged 35 years or older, the overall prevalence of edentulism (35+ years) decreased from 36.4% in 1975 to 5.0% in 2005. Females, respondents in the higher SES group, in more recent survey years, with no denture, and receiving SDC in all grades during childhood were associated with higher probability of seeking ADC regularly (<it>P </it>< 0.05). The interaction of SDC and age (<it>P </it>< 0.0001) was significant. The probabilities of seeking ADC were even higher among subjects with SDC in all grades and aged 45 years or older. Females, older age group, respondents in earlier survey years, not seeking ADC, lower SES group, and not receiving SDC in all grades were associated with higher probability of being edentulous (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>With the use of GEE, the potential clustering effect of birth cohorts in sequential cross-sectional oral health survey data could be appropriately considered. The success of Danish dental health policy was demonstrated by a continued increase of regular dental visiting habits and tooth retention in adults because school dental care was provided to Danes in their childhood.</p

    Value of a UK medical degree for international students (VISION): a cross-sectional study

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    Objectives: It is estimated that NHS staff consist of over 200 different nationalities, with a reported 30.7% of doctors holding a nationality other than British. Despite this, international medical students represent 7.5% of all medical students studying in the UK and pay on average, 4–6 times more in tuition fees when compared with the £9250 per annum (Great British Pounds (£) in 2021) paid by home students. This study’s aim and objective are to evaluate the perception of the financial cost and value of the UK medical degree for international students and their motivations for pursuing such a degree. Methods: This is a cross-sectional observational study enquiring about international premedical, medical and medical school graduates’ perception of the value of the UK medical degree and factors influencing their decision to study in the UK. A questionnaire was developed and distributed to 24 medical schools and 64 secondary schools both internationally and across the UK. Results: A total of 352 responses from 56 nationalities were recorded. 96% of international students identified clinical and academic opportunities as the most important factors to study medicine in the UK, closely followed by quality of life (88%). The least important factor was family reasons, with 39% of individuals identifying this factor. Only 4.82% of graduates in our study considered leaving the UK after training. Overall, 54% of students felt the UK degree was value for money. This belief was significantly higher in premedical students compared with existing students and graduates (71% vs 52% and 20%, p<0.001 for all comparisons). Conclusion: The quality of medical education and international prestige are attractive factors for international students to study medicine in the UK. However, further work is needed to ascertain reasons for the differing perceptions of the value by international students at different stages in their clinical training

    Robust estimation of bacterial cell count from optical density

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    Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

    Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

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    Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P &lt; 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV
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