Publications by authors named "Wickramasinghe R"

The spatial distribution of organics in geological samples can be used to determine when and how these organics were incorporated into the host rock. Mass spectrometry (MS) imaging can rapidly collect a large amount of data, but ions produced are mixed without discrimination, resulting in complex mass spectra that can be difficult to interpret. Here, we apply unsupervised and supervised machine learning (ML) to help interpret spectra from time-of-flight-secondary ion mass spectrometry (ToF-SIMS) of an organic-carbon-rich mudstone of the Middle Jurassic of England (UK).

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Introduction And Objectives: Sri Lankans do not have a specific cardiovascular (CV) risk prediction model and therefore, World Health Organization(WHO) risk charts developed for the Southeast Asia Region are being used. We aimed to develop a CV risk prediction model specific for Sri Lankans using machine learning (ML) of data of a population-based, randomly selected cohort of Sri Lankans followed up for 10 years and to validate it in an external cohort.

Material And Methods: The cohort consisted of 2596 individuals between 40-65 years of age in 2007, who were followed up for 10 years.

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Adolescence is a crucial phase of growth and development in the life course, and healthy nutrition is essential during this period. The objective of this study was to explore the perceptions regarding the implementation of relevant nutrition policies for adolescents in Sri Lanka. The study is qualitative, employing a "phenomenology" approach.

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Elevated right ventricular pacing (RVP) burdens are associated with the development of pacing-induced cardiomyopathy. This association is alluded to in the recent European and American pacing guidelines where anticipated pacing burden forms part of the indications for conduction system pacing. Understanding the temporal pattern of RVP burden is important with respect to anticipating future burden and ensuring that the most appropriate pacing modality is selected for patients.

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The ability to detect and map lipids, including potential lipid biomarkers, within a sedimentary matrix using mass spectrometry (MS) imaging may be critical to determine whether potential lipids detected in samples returned from Mars are indigenous to Mars or are contaminants. Here, we use gas chromatography-mass spectrometry (GC-MS) and time-of-flight-secondary ion mass spectrometry (ToF-SIMS) datasets collected from an organic-rich, thermally immature Jurassic geologic sample to constrain MS imaging analysis of indigenous lipid biomarkers in geologic samples. GC-MS data show that the extractable fractions are dominated by C-C steranes and sterenes as well as isorenieratene derivatives.

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Strokes are among the leading causes of death worldwide. Ischemic stroke, due to plaque or other buildup blocking blood flow to the brain, is the most common type. Although ischemic stroke is treatable, current methods have severe shortcomings with high mortality rates.

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Background: Since the outbreak of the coronavirus (SARS-Cov-2), wearing personal protective equipment (PPE) has become necessary. Patients' ability to recognize staff is disrupted impacting on the relationship between healthcare worker and patient.

Objective: Assess the patients' perspective of healthcare workers wearing PPE and its effect on communication.

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The study of lipid molecular fossils by traditional biomarker analysis requires bulk sample crushing, followed by solvent extraction, and then the analysis of the extract by gas chromatography-mass spectrometry (GC-MS). This traditional analysis mixes all organic compounds in the sample regardless of their origins, with a loss of information on the spatial distribution of organic molecules within the sample. These shortcomings can be overcome using the chemical mapping of intact samples.

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Although covalent organic frameworks (COFs) have earned significant interest in separation applications, the use of COFs in biomolecule separation remains unexplored. We examined the ionic COF Py-BPy-COF as an ion exchange material for biomolecule separation. After characterizing the properties of the synthesized COF with a variety of techniques, binding experiments with both large and small biomolecules were performed.

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Femtosecond laser desorption postionization mass spectrometry using 7.9 eV single-photon ionization (7.9 eV fs-LDPI-MS) detected three of four drug compounds previously found to have very low ionization efficiencies by secondary ion mass spectrometry.

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Nanofiltration membranes have evolved as a promising solution to tackle the clean water scarcity and wastewater treatment processes with their low energy requirement and environment friendly operating conditions. Thin film composite nanofiltration membranes with high permeability, and excellent antifouling and antibacterial properties are important component for wastewater treatment and clean drinking water production units. In the scope of this study, thin film composite nanofiltration membranes were fabricated using polyacrylonitrile (PAN) support and fast second interfacial polymerization modification methods by grafting polyethylene amine and zwitterionic sulfobutane methacrylate moieties.

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Objective: To compare the safety of keeping an intrauterine Foley catheter for 48 hours versus 24 hours for cervical ripening.

Methods: A randomized controlled trial was conducted at the De Soysa Hospital for Women, Sri Lanka from April 1 to December 31, 2014 (trial registration: SLCTR/2014/006). Low-risk women with a Bishop score ≤5 at 40 weeks + 5 days of gestation were allocated to either 24-hour (n=107; Group A) or 48-hour (n=94; Group B) groups.

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Background: The metabolic syndrome (MetS) is a clustering of abdominal obesity, diabetes and prediabetes, high cholesterol and high blood pressure, that confers an increased risk of cardiovascular disease. There is limited data on incidence of MetS from South Asia. This study investigated incidence and risk factors for new onset MetS in an urban adult Sri Lankan population.

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A combined pore blockage and cake filtration model was applied to the virus filtration of an Fc-fusion protein using the three commercially available filters, F-1, F-2, and F-3 in a range of buffer conditions including sodium-phosphate and tris-acetate buffers with and without 200 mM NaCl at pH 7.5. The fouling behaviors of the three filters for the feed solutions spiked with minute virus of mice were described well by this combined model for all the solution conditions.

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Direct contact membrane distillation (DCMD) has been conducted to treat hydraulic fracturing-produced water using polyvinylidenedifluoride (PVDF) membranes. Tailoring the surface properties of the membrane is critical in order to reduce the rate of adsorption of dissolved organic species as well as mineral salts. The PVDF membranes have been modified by grafting zwitterion and polyionic liquid-based polymer chains.

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Lasers with pulse lengths from nanoseconds to femtoseconds and wavelengths from the mid-infrared to extreme ultraviolet (UV) have been used for desorption or ablation in mass spectrometry. Such laser sampling can often benefit from the addition of a second laser for postionization of neutrals. The advantages offered by laser postionization include the ability to forego matrix application, high lateral resolution, decoupling of ionization from desorption, improved analysis of electrically insulating samples, and potential for high sensitivity and depth profiling while minimizing differential detection.

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This article presents the synthesis of poly(methacrylic acid)-b-poly(methyl methacrylate) diblock copolymer via polymerization-induced self-assembly in the presence of iron-oxide nanoparticles. Detailed phase diagrams with and without inorganic nanoparticles were constructed. Scanning transmission electron microscopy and energy dispersive X-ray photometry studies confirme the decoration of the polymeric nanoparticles with the iron-oxide nanoparticles.

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A hand-held diode laser is implemented for solid sampling in portable ambient mass spectrometry (MS). Specifically, a pseudocontinuous wave battery-powered surgical laser diode is employed for portable laser diode thermal desorption (LDTD) at 940 nm and compared with nanosecond pulsed laser ablation at 2940 nm. Postionization is achieved in both cases using atmospheric pressure photoionization (APPI).

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Background: This study investigated incidence and risk factors for NAFLD among an adult cohort with 7-year follow-up.

Methods: The study population (age-stratified random sampling, Ragama MOH area) was screened initially in 2007 (aged 35-64 years) and re-evaluated in 2014 (aged 42-71 years). On both occasions assessed by structured interview, anthropometric measurements, liver ultrasound, biochemical and serological tests.

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Background: Extended Spectrum Beta- Lactamase producing organisms causing urinary tract infections (ESBL-UTI) are increasing in incidence and pose a major burden to health care. While ESBL producing Klebsiella species seem to account for most nosocomial outbreaks, ESBL-producing E. coli have been isolated from both hospitalized and non-hospitalized patients.

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Background: Thyrotoxic crisis is a medical emergency requiring early diagnosis and urgent management, which can be challenging due to its diverse clinical presentations. While common presentations include fever, sweating, palpitations, tremors and confusion, presence of jaundice is rare.

Case Presentation: We report a 35-year-old male who presented with jaundice due to cholestasis along with other features of thyrotoxic crisis due to Graves' disease.

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The presence of thoracic aortic aneurysms, particularly in the ascending aorta and arch, presents a challenge to transcatheter aortic valve replacement. We present a case of TAVR in the presence of a chronic ascending aortic aneurysm. doi: 10.

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Background: Leptospirosis is diagnosed on clinical grounds, and confirmed by microscopic agglutination test (MAT). IgM-ELISA (Serion-Virion) and immunochromatography test (Leptocheck-WB) are two immunodiagnostic assays for leptospirosis. Their sensitivity, specificity and applicability in Sri Lanka have not been systematically evaluated.

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Pruritus is an important symptom in psoriasis with no targeted treatment. Tropomyosin-receptor kinase A (TrkA) is associated with pruritus and psoriatic plaque formation. We report the efficacy of a TrkA inhibitor, CT327, on pruritus in psoriasis.

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