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1.
J Colloid Interface Sci ; 648: 418-426, 2023 Oct 15.
Article in English | MEDLINE | ID: mdl-37302225

ABSTRACT

By virtue of their low density and thermal conductivity, aerogels constitute attractive thermal insulators. Of those, aerogel films are best suited for thermal insulation in microsystems. Processes for the synthesis of aerogel films with thicknesses smaller than 2 µm or thicker than 1 mm are well established. However, for microsystems films in the range of a few microns and up to several hundred microns would be beneficial. To circumvent the present limitations, we describe a liquid mold made of two immiscible liquids, used here to produce aerogel films thicker than 2 µm in a single molding step. Following gelation and aging, the gels were removed from the liquids and dried using supercritical carbon dioxide. In contrast to spin/dip coating, liquid molding avoids solvent evaporation from the gel's outer surface during gelation and aging, films are free-standing and have smooth surfaces. The choice of liquids determines the aerogel film thickness. As a proof of concept, 130 µm thick homogeneous and high porosity (>90%) silica aerogel films were synthesized in a liquid mold with fluorine oil and octanol. The resemblance of the liquid mold approach to the float glass technique offers the prospect of mass production of large sheets of aerogel films.

2.
ACS Appl Mater Interfaces ; 15(5): 7466-7484, 2023 Feb 08.
Article in English | MEDLINE | ID: mdl-36705276

ABSTRACT

Increasing the security of anticounterfeiting materials has been the most important challenge in recent years, and the development of dual-color photoluminescent inks with multi-level security, static/dynamic emission, and dynamic color change is an important solution to overcome this problem. In this study, the multi-functionalized copolymer nanoparticles containing different functional groups (with a concentration of 20 wt %), including ester, carboxylic acid, hydroxyl, epoxide, amide, and amine groups were synthesized successfully by the emulsion polymerization method. The results showed that the particle size and morphology of nanoparticles are affected by the polarity of functional groups. The prepared multi-functionalized copolymer nanoparticles were modified physically with spiropyran (photochromic and red fluorescence emission) and coumarin (cyan emission) derivatives to develop dual-color photoluminescent polymer nanoparticles with application in static-dynamic photoluminescent anticounterfeiting inks, which have multi-level security. The investigation of optical properties indicates that the kinetics of photochromism and photoluminescence properties of samples containing spiropyran is dependent on the local polarity on the surface of polymer nanoparticles. Hence, an increase in the polarity (functionalization with amide, carboxylic acid, and hydroxyl groups) has resulted in fast photochromism, high-intensity photoluminescence emission and increased the efficiency of the photoswitchable color change of emission from cyan to pink. Dual-color photoluminescent anticounterfeiting inks were prepared by mixing polymer nanoparticles containing spiropyran with polymer nanoparticles containing coumarin, in different ratios (1:1, 1:3, 1:5, 1:8, and 1:10). Obtained results showed that prepared samples have cyan emission under UV light of 254 nm (static mode), and a dynamic photoswitching of fluorescence emission from cyan to pink (as a function of irradiation time) was also observed under UV-light irradiation of 365 nm, which is well known as a dynamic mode of emission. The responsivity and intensity of dynamic photoluminescence emission are dependent on the local polarity of the surface functional groups, in which the samples based on amide functionalized copolymer nanoparticles displayed high-intensity emission in the static mode and high-intensity photoswitchable dual-color emission in the dynamic mode, in the case of all ratios of colloid solution mixtures. Printing security tags on cellulose paper by dual-color photoluminescent inks indicates advantages such as maximum printability, resolution, brightness, and static-dynamic photoluminescence emission with high intensity for inks based on amide functionalized nanoparticles. The static-dynamic dual-color photoluminescent anticounterfeiting ink with unique properties and multi-level security was reported for the first time by the collaboration of spiropyran and coumarin. This study can open a new approach and window to the future of advanced and high-security anticounterfeiting technologies.

3.
J Chem Phys ; 158(3): 034702, 2023 Jan 21.
Article in English | MEDLINE | ID: mdl-36681626

ABSTRACT

Silica-based aerogels are a promising low-cost solution for improving the insulation efficiency of single-pane windows and reducing the energy consumption required for space heating and cooling. Two key material properties required are high porosity and small pore sizes, which lead to low thermal conductivity and high optical transparency, respectively. However, porosity and pore size are generally directly linked, where high porosity materials also have large pore sizes. This is unfavorable as large pores scatter light, resulting in reduced transmittance in the visible regime. In this work, we utilized preformed silica colloids to explore methods for reducing pore size while maintaining high porosity. The use of preformed colloids allows us to isolate the effect of solution conditions on porous gel network formation by eliminating simultaneous nanoparticle growth and aggregation found when using typical sol-gel molecular-based silica precursors. Specifically, we used in situ synchrotron-based small-angle x-ray scattering during gel formation to better understand how pH, concentration, and colloid size affect particle aggregation and pore structure. Ex situ characterization of dried gels demonstrates that peak pore widths can be reduced from 15 to 13 nm, accompanied by a narrowing of the overall pore size distribution, while maintaining porosities of 70%-80%. Optical transparency is found to increase with decreasing pore sizes while low thermal conductivities ranging from 95 +/- 13 mW/m K are maintained. Mechanical performance was found to depend primarily on effective density and did not show a significant dependence on solution conditions. Overall, our results provide insights into methods to preserve high porosity in nanoparticle-based aerogels while improving optical transparency.


Subject(s)
Nanoparticles , Silicon Dioxide , Silicon Dioxide/chemistry , X-Rays , Gels/chemistry , Colloids , Porosity
4.
J Colloid Interface Sci ; 630(Pt A): 242-256, 2023 Jan 15.
Article in English | MEDLINE | ID: mdl-36242884

ABSTRACT

Photoluminescent polymer nanoparticles based on organic compounds are a new category of advanced materials with potential applications in various fields such as chemosensors, optical devices, drug-delivery systems, anticounterfeiting inks and bioimaging. Herein, amide functionalized copolymer nanoparticles with a particle size in the range of 42-139 nm were synthesized by emulsion copolymerization of methylmathacrylate (MMA) and methacrylamide (MAAm) with different concentrations in the range of 0-20 wt%. Afterward, the photoluminescent copolymer nanoparticles (PLCNPs) were prepared by physical modification of amide functionalized copolymer nanoparticles with 5 wt% of oxazolidine derivative (OXOH). Investigation of optical properties include of photoluminescence and UV-vis spectra displayed significant dependency of emission and absorbance bands to the local polarity or the concentration of the amide groups on the surface of the nanoparticles. Study of Commission Internationale de l'Eclairage (CIE) colorimetric diagrams for PLCNPs samples confirmed the results of photoluminescence and UV-vis spectra, which a logical shift in color of the photoluminescence emission was observed by an increase in the concentration of the amide groups. The PLCNPs samples have remarkable stability (in physical and optical properties) when applied on polar substrates such as polymer sheet and cellulose paper. Therefore, the PLCNPs samples were used for development of eco-friendly water based anticounterfeiting inks, photoluminescence organic light emitting diodes (OLEDs), and also the photodetection of scratches in a fast and facile manner. The printed security tags and hand-written phrases on cellulosic papers have orange fluorescent emission with maximum intensity because nanoscale size of particles, which reduced the light scattering and increased the accessible concentration of OXOH for light absorption. A coating of poly(vinyl alcohol) (PVA)/PLCNPs solution onto a blue LED (365 nm) was led to a change in the color of emission from blue to purple, because of the excitation of OXOH molecules at 365 nm with the subsequent emission of purple light. The photodetection of created scratch on polycarbonate sheet was carried out by spray of PLCNPs solution on sheet and then illumination with UV irradiation (365 nm). Developed water based PLCNPs samples have interesting optical properties, high stability on different surfaces and nanoscale particle size which are applicable in multiple applications such as eco-friendly photoluminescent inks for anticounterfeiting technologies, photoluminescence OLEDs, and also optical detector for monitoring of scratches on different substrates.


Subject(s)
Nanoparticles , Polymers , Polymers/chemistry , Nanoparticles/chemistry , Water , Amides
5.
Front Med (Lausanne) ; 9: 933996, 2022.
Article in English | MEDLINE | ID: mdl-35860742

ABSTRACT

Introduction: Few data exist regarding the immunogenicity of the third dose of BNT162b2 relative to the second dose in patients with inflammatory bowel disease (IBD) on different immunosuppressive therapies. We investigated the immunogenicity of BNT162b2 vaccine booster dose in patients with IBD on infliximab combination therapy. Method: This is a prospective single-center observational study conducted from January 1, 2022 to February 28, 2022. Patients were recruited at the time of attendance at the infusion center. Eligibility criteria included patients with a confirmed diagnosis of IBD who are receiving infliximab with azathioprine or 6-mercaptopurine. Patients who received two doses of BNT162b2 vaccine (second dose group) were compared to patients who had received three doses of BNT162b2 vaccine [third dose (booster) group]. Patients were excluded if they were infected or had symptoms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) previously since the start of the pandemic or received other vaccines than the BNT162b2. Our primary outcome was the concentrations of SARS-CoV-2 antibodies Immunoglobulin G (IgG) and neutralizing antibodies 40-45 weeks from the first dose of BNT162b2 vaccine in patients with IBD receiving infliximab combination therapy. Medians with interquartile range (IQR) were calculated. Results: In total, 162 patients with IBD and receiving infliximab combination therapy were recruited, and the number of patients in both the second dose group and third dose (booster) group was 81. Mean age was 35 years old in both groups. Median (IQR) SARS-CoV-2 IgG levels were significantly lower after the second dose [125 BAU/ml (43, 192)] compared to patients who received the third booster dose [207 BAU/ml (181, 234)] (P = 0.003). Neutralizing antibody levels were also lower after the second dose [80% (21, 95)] compared to patients who received the third booster dose [96% (93, 99)] (P ≤ 0.001). The percentage of patients who achieved positive SARS-CoV-2 IgG levels in the third (booster) dose group was 96.3%, whereas it was 86.4% in the second dose group. The percentage of participants who received the third (booster) dose and achieved a positive SARS-CoV-2-neutralizing antibody level was 100%, whereas it was 88.9% in the participants who received the second dose only. Conclusion: Most patients with IBD on infliximab combination therapy had positive SARS-CoV-2 IgG and neutralizing antibody concentrations 40-45 weeks post BNT162b2 vaccination. However, SARS-CoV-2 IgG and neutralizing antibody concentrations were lower in patients who received two doses only compared to patients who received a third dose. A longer follow-up study is needed to evaluate decay in antibodies over time.

6.
J Colloid Interface Sci ; 606(Pt 1): 884-897, 2022 Jan 15.
Article in English | MEDLINE | ID: mdl-34454313

ABSTRACT

This paper presents a novel sol-gel method to synthesize large and thick silica aerogel monoliths at near ambient conditions using a commercial aqueous solution of colloidal silica nanoparticles as building blocks. To achieve slabs with high visible transmittance and low thermal conductivity, the method combines the strategies of (i) synthesizing gels on an omniphobic perfluorocarbon liquid substrate, (ii) aging at temperatures above room temperature, and (iii) performing solvent exchange with a low-surface-tension organic solvent prior to ambient drying. The omniphobic liquid substrates were used to prevent cracking and ensure an optically-smooth surface, while nanoparticle building blocks were small (<10 nm) to limit volumetric light scattering. Gels were aged at temperatures between 25 and 80 °C for up to 21 days to make them stronger and stiffer and to reduce shrinkage and cracking during ambient drying. Ambient drying was achieved by first exchanging water in the gel pores for octane, followed by drying in an octane-rich atmosphere to decrease capillary forces. The synthesized nanoparticle-based silica aerogel monoliths had thicknesses up to 5 mm, diameters up to 10 cm, porosities exceeding 80%, and thermal conductivities as low as 0.08 W m-1 K-1. Notably, the slabs featured visible transmittance exceeding 75% even for slabs as thick as 5 mm. The as-synthesized aerogel monoliths were exposed to TMCS vapor to induce hydrophobic properties resulting in a water contact angle of 140° that prevented water infiltration into the pores and protected the aerogels from water damage. This simple synthesis route conducted at near ambient conditions produces hydrophobic aerogel monoliths with promising optically transparent and thermally insulating properties that can be adhered to glass panes for window insulation and solar-thermal energy conversion applications.


Subject(s)
Nanoparticles , Silicon Dioxide , Gels , Suspensions , Thermal Conductivity
7.
Front Public Health ; 9: 778243, 2021.
Article in English | MEDLINE | ID: mdl-34926392

ABSTRACT

Background: The emergence of new COVID-19 variants of concern coupled with a global inequity in vaccine access and distribution has prompted many public health authorities to circumvent the vaccine shortages by altering vaccination protocols and prioritizing persons at high risk. Individuals with previous COVID-19 infection may not have been prioritized due to existing humoral immunity. Objective: We aimed to study the association between previous COVID-19 infection and antibody levels after COVID-19 vaccination. Methods: A serological analysis to measure SARS-CoV-2 immunoglobulin (Ig)G, IgA, and neutralizing antibodies was performed on individuals who received one or two doses of either BNT162b2 or ChAdOx1 vaccines in Kuwait. A Student t-test was performed and followed by generalized linear regression models adjusted for individual characteristics and comorbidities were fitted to compare the average levels of IgG and neutralizing antibodies between vaccinated individuals with and without previous COVID-19 infection. Results: A total of 1,025 individuals were recruited. The mean levels of IgG, IgA, and neutralizing antibodies were higher in vaccinated subjects with previous COVID-19 infections than in those without previous infection. Regression analysis showed a steeper slope of decline for IgG and neutralizing antibodies in vaccinated individuals without previous COVID-19 infection compared to those with previous COVID-19 infection. Conclusion: Previous COVID-19 infection appeared to elicit robust and sustained levels of SARS-CoV-2 antibodies in vaccinated individuals. Given the inconsistent supply of COVID-19 vaccines in many countries due to inequities in global distribution, our results suggest that even greater efforts should be made to vaccinate more people, especially individuals without previous COVID-19 infection.


Subject(s)
COVID-19 Vaccines , COVID-19 , BNT162 Vaccine , Humans , SARS-CoV-2 , Vaccination
8.
ACS Appl Mater Interfaces ; 13(37): 44878-44892, 2021 Sep 22.
Article in English | MEDLINE | ID: mdl-34506114

ABSTRACT

Investigation of developed photoactive security inks and anticounterfeiting technologies in recent years indicates significant challenges for future of this research area, such as increase of security, fast responsivity, and facile authentication. Here, amine-functionalized latex nanoparticles were synthesized by emulsion copolymerization of methyl methacrylate (MMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). Size of the latex nanoparticles was increased as a function of poly(dimethylaminoethyl acrylate) (PDMAEMA) contents, and also a decrease of particle size was obtained in response to an increase of temperature from 25 to 70 °C, above the lower critical solution temperature (LCST) of PDMAEMA. Surface physical modification of the functional latex nanoparticle with spiropyran photoswitches led to the development of anticounterfeiting nanoinks that have multilevel security and photochromic/fluorescence properties with a higher intensity and also brightness. The photoluminescent nanoinks were made of spiropyran latex nanoparticles and used for printing of the encoded optical security tags on cellulosic papers and banknotes. The results displayed that an increase of the particle size above 100 nm and an increase of the PDMAEMA contents led to a remarkable decrease of printability, fluorescent emission, brightness, intensity of photochromism, and also resolution of the printed security tags. As a significant advantage of the developed security inks, the printed security tags could be authenticated easily and fast upon sunlight irradiation by means of photochromism. The responsivity of encoded tags from the invisible to visible state is immediate upon sunlight irradiation for some seconds, whose intensity of coloration is appropriate and detectable clearly by naked eyes. The security anticounterfeiting inks based on spiropyran with multilevel security have been reported for the first time for applying in printing of encoded security tags on cellulosic papers, banknotes, and other documents, where the printed marks are detectable on sunlight exposure.

9.
Sci Rep ; 11(1): 12190, 2021 Jun 09.
Article in English | MEDLINE | ID: mdl-34108492

ABSTRACT

Mahallat Geothermal Region, located in the central part of Iran, is known as one of the largest low-temperature geothermal fields. In this study, Mahallat geothermal resource has been evaluated based on integrated geological, geochemical and geophysical analyses. Gravity data revealed three major negative anomaly zones. Based on the geochemical analyses, quartz geothermometers are more reliable than others and confirmed that the reservoir is about 90 °C. Lithological properties of Jurassic layers and high sulphate content observed in geochemical data showed traces of the coal-rich layers on the hot fluids. Measured temperatures in 7 boreholes with the depths ranging from 50 to 100 m, have proposed that expected geothermal gradient will be about 81.5 °C/km. Among all drilled boreholes, the data coming from only one resulted in this almost reliable gradient. Other boreholes are clearly too shallow or affected by upflow or downflow of water along existing faults. Geological, geochemical, gravity and measurements of drilled boreholes suggested the existence of a shallow reservoir with an approximate temperature of 90 °C. Regarding gravity and observed faults, geothermal reservoir is elongated parallel to one of the main faults of the region with NE-SW strike.

10.
Heliyon ; 7(4): e06706, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33842709

ABSTRACT

BACKGROUND: COVID-19 has a highly variable clinical presentation, ranging from asymptomatic to severe respiratory symptoms and death. Diabetes seems to be one of the main comorbidities contributing to a worse COVID-19 outcome. OBJECTIVE: In here we analyze the clinical characteristics and outcomes of diabetic COVID-19 patients Kuwait. METHODS: In this single-center, retrospective study of 417 consecutive COVID-19 patients, we analyze and compare disease severity, outcome, associated complications, and clinical laboratory findings between diabetic and non-diabetic COVID-19 patients. RESULTS: COVID-19 patients with diabetes had more ICU admission than non-diabetic COVID-19 patients (20.1% vs. 16.8%, p < 0.001). Diabetic COVID-19 patients also recorded higher mortality in comparison to non-diabetic COVID-19 patients (16.7% vs. 12.1%, p < 0.001). Diabetic COVID-19 patients had significantly higher prevalence of comorbidities, such as hypertension. Laboratory investigations also highlighted notably higher levels of C-reactive protein in diabetic COVID019 patients and lower estimated glomerular filtration rate. They also showed a higher incidence of complications. logistic regression analysis showed that every 1 mmol/L increase in fasting blood glucose in COVID-19 patients is associated with 1.52 (95% CI: 1.34-1.72, p < 0.001) times the odds of dying from COVID-19. CONCLUSION: Diabetes is a major contributor to worsening outcomes in COVID-19 patients. Understanding the pathophysiology underlining these findings could provide insight into better management and improved outcome of such cases.

11.
PLoS One ; 15(11): e0242768, 2020.
Article in English | MEDLINE | ID: mdl-33216801

ABSTRACT

This is a retrospective single-center study of 417 consecutive patients with coronavirus disease 2019 (COVID-19) admitted to Jaber Al-Ahmad Hospital in Kuwait between February 24, 2020 and May 24, 2020. In total, 39.3% of patients were asymptomatic, 41% were symptomatic with mild/moderate symptoms, 19.7% were admitted to the intensive care unit (ICU). Most common symptoms in cohort patients were fever (34.3%) and dry cough (32.6%) while shortness in breath was reported in (75.6%) of ICU admissions. Reported complications requiring ICU admission included Sepsis (68.3%), acute respiratory distress syndrome (95.1%) and heart failure (63.4%). ICU patients were more likely to have comorbidities, in comparison to non-ICU patients, including diabetes (35.4% vs 20.3%) and hypertension (40.2% vs 26.9%). Mortality rate of cohort was 14.4% and mean age of death was 54.20 years (± 11.09) and 90% of death cases were males. Chest high-resolution computed tomography for ICU cases reveled multifocal large patchy areas of ground glass opacification mixed with dense consolidation. Cases admitted to ICU showed abnormal levels of markers associated with infection, inflammation, abnormal blood clotting, heart problems and kidney problems. Mean hospital stay for asymptomatic cases was 20.69 days ±8.57 and for mild/moderate cases was 21.4 days ±8.28. Mean stay in ICU to outcome for survivors was 11.95 days ±8.96 and for death cases 13.15 days ±10.02. In this single-center case series of 417 hospitalized COVID-19 patients in Kuwait 39.3% were asymptomatic cases, 41% showed mild/moderate symptoms and 18.7% were admitted to ICU with a mortality rate of 14.4%.


Subject(s)
Coronavirus Infections/epidemiology , Pneumonia, Viral/epidemiology , Adolescent , Adult , Aged , Aged, 80 and over , Asymptomatic Infections/epidemiology , Betacoronavirus , COVID-19 , Child , Child, Preschool , Comorbidity , Female , Humans , Infant , Infant, Newborn , Intensive Care Units , Kuwait/epidemiology , Male , Middle Aged , Pandemics , Retrospective Studies , SARS-CoV-2 , Young Adult
12.
Nat Commun ; 11(1): 4734, 2020 09 18.
Article in English | MEDLINE | ID: mdl-32948759

ABSTRACT

A primary reason for the intense interest in structural biology is the fact that knowledge of structure can elucidate macromolecular functions in living organisms. Sustained effort has resulted in an impressive arsenal of tools for determining the static structures. But under physiological conditions, macromolecules undergo continuous conformational changes, a subset of which are functionally important. Techniques for capturing the continuous conformational changes underlying function are essential for further progress. Here, we present chemically-detailed conformational movies of biological function, extracted data-analytically from experimental single-particle cryo-electron microscopy (cryo-EM) snapshots of ryanodine receptor type 1 (RyR1), a calcium-activated calcium channel engaged in the binding of ligands. The functional motions differ substantially from those inferred from static structures in the nature of conformationally active structural domains, the sequence and extent of conformational motions, and the way allosteric signals are transduced within and between domains. Our approach highlights the importance of combining experiment, advanced data analysis, and molecular simulations.


Subject(s)
Calcium Channel Agonists/chemistry , Macromolecular Substances/chemistry , Ryanodine Receptor Calcium Release Channel/chemistry , Binding Sites , Cryoelectron Microscopy , Ligands , Molecular Conformation , Molecular Dynamics Simulation , Ryanodine Receptor Calcium Release Channel/metabolism
13.
Lancet Digit Health ; 2(7): e368-e375, 2020 07.
Article in English | MEDLINE | ID: mdl-32617525

ABSTRACT

Background: Preterm birth is a major global health challenge, the leading cause of death in children under 5 years of age, and a key measure of a population's general health and nutritional status. Current clinical methods of estimating fetal gestational age are often inaccurate. For example, between 20 and 30 weeks of gestation, the width of the 95% prediction interval around the actual gestational age is estimated to be 18-36 days, even when the best ultrasound estimates are used. The aims of this study are to improve estimates of fetal gestational age and provide personalised predictions of future growth. Methods: Using ultrasound-derived, fetal biometric data, we developed a machine learning approach to accurately estimate gestational age. The accuracy of the method is determined by reference to exactly known facts pertaining to each fetus-specifically, intervals between ultrasound visits-rather than the date of the mother's last menstrual period. The data stem from a sample of healthy, well-nourished participants in a large, multicentre, population-based study, the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st). The generalisability of the algorithm is shown with data from a different and more heterogeneous population (INTERBIO-21st Fetal Study). Findings: In the context of two large datasets, we estimated gestational age between 20 and 30 weeks of gestation with 95% confidence to within 3 days, using measurements made in a 10-week window spanning the second and third trimesters. Fetal gestational age can thus be estimated in the 20-30 weeks gestational age window with a prediction interval 3-5 times better than with any previous algorithm. This will enable improved management of individual pregnancies. 6-week forecasts of the growth trajectory for a given fetus are accurate to within 7 days. This will help identify at-risk fetuses more accurately than currently possible. At population level, the higher accuracy is expected to improve fetal growth charts and population health assessments. Interpretation: Machine learning can circumvent long-standing limitations in determining fetal gestational age and future growth trajectory, without recourse to often inaccurately known information, such as the date of the mother's last menstrual period. Using this algorithm in clinical practice could facilitate the management of individual pregnancies and improve population-level health. Upon publication of this study, the algorithm for gestational age estimates will be provided for research purposes free of charge via a web portal. Funding: Bill & Melinda Gates Foundation, Office of Science (US Department of Energy), US National Science Foundation, and National Institute for Health Research Oxford Biomedical Research Centre.


Subject(s)
Data Accuracy , Fetal Development/physiology , Machine Learning , Algorithms , Biometry , Female , Gestational Age , Humans , Internationality , Pregnancy , Prospective Studies , Ultrasonography
14.
Preprint in English | medRxiv | ID: ppmedrxiv-20098954

ABSTRACT

The Covid-19 first occurs in Wuhan, China in December 2019. After that the virus spread all around the world and at the time of writing this paper the total number of confirmed cases are above 4.7 million with over 315000 deaths. Machine learning algorithms built on radiography images can be used as a decision support mechanism to aid radiologists to speed up the diagnostic process. The aim of this work is to conduct a critical analysis to investigate the applicability of convolutional neural networks (CNNs) for the purpose of COVID-19 detection in chest X-ray images and highlight the issues of using CNN directly on the whole image. To achieve this task, we first use 12-off-the-shelf CNN architectures in transfer learning mode on 3 publicly available chest X-ray databases together with proposing a shallow CNN architecture in which we train it from scratch. Chest X-ray images fed into CNN models without any preprocessing to follow the many of researches using chest X-rays in this manner. Next, a qualitative investigation performed to inspect the decisions made by CNNs using a technique known as class activation maps (CAM). Using CAMs, one can map the activations contributed most to the decision of CNNs back to the original image to visualize the most discriminating regions on the input image. We conclude that CNN decisions should not be taken into consideration, despite their high classification accuracy, until clinicians can visually inspect, and approve, the region(s) of the input image used by CNNs that lead to its prediction.

15.
J Chem Inf Model ; 60(5): 2484-2491, 2020 05 26.
Article in English | MEDLINE | ID: mdl-32207941

ABSTRACT

Recent approaches to the study of biological molecules employ manifold learning to single-particle cryo-EM data sets to map the continuum of states of a molecule into a low-dimensional space spanned by eigenvectors or "conformational coordinates". This is done separately for each projection direction (PD) on an angular grid. One important step in deriving a consolidated map of occupancies, from which the free energy landscape of the molecule can be derived, is to propagate the conformational coordinates from a given choice of "anchor PD" across the entire angular space. Even when one eigenvector dominates, its sign might invert from one PD to the next. The propagation of the second eigenvector is particularly challenging when eigenvalues of the second and third eigenvector are closely matched, leading to occasional inversions in their ranking as we move across the angular grid. In the absence of a computational approach, this propagation across the angular space has been done thus far "by hand" using visual clues, thus greatly limiting the general use of the technique. In this work we have developed a method that is able to solve the propagation problem computationally, by using optical flow and a probabilistic graphical model. We demonstrate its utility by selected examples.


Subject(s)
Cryoelectron Microscopy , Molecular Conformation
16.
Cell Stress Chaperones ; 23(5): 955-965, 2018 09.
Article in English | MEDLINE | ID: mdl-29752628

ABSTRACT

Type 2 diabetes mellitus (T2DM) features insulin resistance, hyperglycemia, dyslipidemia, overproduction of inflammatory cytokines, and systemic oxidative stress. Here, heat shock proteins Hsp70 and Hsp 90, adiponectin, and heme oxygenase-1 (HO-1, Hsp32) are profiled in peripheral blood mononuclear cells (PBMC) and serum from 25 T2DM patients and 25 healthy control subjects. Cells cultured with phorbol 12-myristate 13-acetate/ionomycin were evaluated by three-color flow cytometry for immunophenotypic biomarkers. Plasma HO-1, Hsp, and adiponectin levels were assayed by enzyme-linked immunosorbent assay (ELISA). Relative to healthy controls, T2DM patients exhibited significantly elevated plasma Hsp70, and representation of T helper immunophenotypes activated to express inflammatory cytokines, including CD4+ IFN-γ+, CD4+ TNF-α+, CD4+ IL-6+, CD4+ IL-1ß+ T cells, significantly lower representation of CD4+ IL-10+ T cells, plasma adiponectin and cell-associated HO-1 expression-with no significant differences in plasma Hsp90 between T2DM and healthy controls. Plasma HO-1 and adiponectin in T2DM patients inversely correlated with TNF-α and showed inverse correlation between serum LDL and plasma HO-1. Moreover, TNF-α and Hsp90 in T2DM patients correlated positively with fasting blood glucose (FBG). These results demonstrate correlation between potentially pathogenic T cells, HO-1, and adiponectin, additionally revealing a T helper (Th)1-related character of T2DM immunopathogenesis, suggesting potential for novel T cell-related management strategies for T2DM and related co-morbidities.


Subject(s)
Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/immunology , Adiponectin/blood , CD3 Complex/analysis , CD4-Positive T-Lymphocytes/immunology , Cells, Cultured , Correlation of Data , Cytokines/blood , Female , HSP70 Heat-Shock Proteins/blood , HSP90 Heat-Shock Proteins/blood , Heme Oxygenase-1/blood , Humans , Male , Middle Aged
17.
J Med Microbiol ; 67(6): 846-853, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29664716

ABSTRACT

PURPOSE: The molecular epidemiology and resistance mechanisms of carbapenem-resistant Pseudomonas aeruginosa (CRPA) were determined in hospitals in the countries of the Gulf Cooperation Council (GCC), namely, Saudi Arabia, the United Arab Emirates, Oman, Qatar, Bahrain and Kuwait. METHODOLOGY: Isolates were screened for common carbapenem-resistance genes by PCR. Relatedness between isolates was assessed using previously described genotyping methods: an informative-single nucleotide polymorphism MassARRAY iPLEX assay (iPLEX20SNP) and the enterobacterial repetitive intergenic consensus (ERIC)-PCR assay, with selected isolates being subjected to multilocus sequence typing (MLST). Ninety-five non-repetitive isolates that were found to be resistant to carbapenems were subjected to further investigation.Results/Key findings. The most prevalent carbapenemase-encoding gene, blaVIM-type, was found in 37/95 (39 %) isolates, while only 1 isolate (from UAE) was found to have blaIMP-type. None of the CRPA were found to have blaNDM-type or blaKPC-type. We found a total of 14 sequence type (ST) clusters, with 4 of these clusters being observed in more than 1 country. Several clusters belonged to the previously recognized internationally disseminated high-risk clones ST357, ST235, ST111, ST233 and ST654. We also found the less predominant ST316, ST308 and ST823 clones, and novel MLST types (ST2010, ST2011, ST2012 and ST2013), in our collection. CONCLUSION: Overall our data show that 'high-risk' CRPA clones are now detected in the region and highlight the need for strategies to limit further spread of such organisms, including enhanced surveillance, infection control precautions and further promotion of antibiotic stewardship programmes.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Bacterial Proteins/genetics , Carbapenems/therapeutic use , Pseudomonas Infections/epidemiology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/genetics , beta-Lactamases/genetics , Bahrain/epidemiology , DNA, Bacterial/genetics , Hospitals , Kuwait/epidemiology , Microbial Sensitivity Tests , Molecular Epidemiology , Oman/epidemiology , Polymerase Chain Reaction , Polymorphism, Single Nucleotide/genetics , Pseudomonas Infections/drug therapy , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/isolation & purification , Qatar/epidemiology , Risk , Saudi Arabia/epidemiology , United Arab Emirates/epidemiology
18.
Front Microbiol ; 8: 1359, 2017.
Article in English | MEDLINE | ID: mdl-28775716

ABSTRACT

The objective of this investigation was to identify the lineages of MRSA and MSSA with reduced susceptibility to chlorhexidine in Kuwaiti hospitals. 121 clinical MRSA and 56 MSSA isolates were included in this study. Antimicrobial susceptibility testing was performed for a selection of agents including chlorhexidine and resistance genes were amplified and sequenced. PFGE, spa typing, and MLST were completed for a selection of isolates. The results showed SCCmec II, III, IV, and V were present in 0.8, 21.5, 69.4, and 8.3% of the MRSA isolates. agr-1Sa was the most prevalent type in both MSSA (48%) and MRSA (54%). Forty-five percentage of MRSA contained pvl and 39% contained lukE-lukD, however, as many as 86% of MSSA contained pvl and 96.4% contained lukE-lukD. qac A-C genes were identified in 12.3% of MRSA, norA was present in 82.6% and blaZ in 94.2%. Among MSSA only 5.4% harbored qacA, 83% contained norA, and 91% blaZ. Multi-drug resistant ST239/t945 lineage containing a qac gene was the most identified S. aureus. However, other lineages, including ST772-MRSA-V/t4867/pvl(+)qacC/smr and non-qac harboring lineages of ST217-MRSAIV/t3244/pvl(-), ST34-MSSA/t161/pvl(+), ST5-MSSA/t688/pvl(+), ST5-MSSA/t4867/norA(+), and ST672-MSSA/t003/pvl(-), also showed reduced susceptibility to chlorhexidine. The observed reduced susceptibility of non-qac dependent MSSA isolates to chlorhexidine suggests the involvement of other elements in promoting higher MBC (≥30 mg/L). Our results confirm that monitoring MSSA is essential as they may have the potential to survive low level biocide exposure.

19.
Nat Methods ; 14(9): 877-881, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28805793

ABSTRACT

Using a manifold-based analysis of experimental diffraction snapshots from an X-ray free electron laser, we determine the three-dimensional structure and conformational landscape of the PR772 virus to a detector-limited resolution of 9 nm. Our results indicate that a single conformational coordinate controls reorganization of the genome, growth of a tubular structure from a portal vertex and release of the genome. These results demonstrate that single-particle X-ray scattering has the potential to shed light on key biological processes.


Subject(s)
Algorithms , Bacteriophages/ultrastructure , Crystallography, X-Ray/methods , DNA, Viral/ultrastructure , Imaging, Three-Dimensional/methods , Scattering, Small Angle , Molecular Conformation , Reproducibility of Results , Sensitivity and Specificity
20.
J Ethnopharmacol ; 194: 1069-1077, 2016 Dec 24.
Article in English | MEDLINE | ID: mdl-27989874

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetea tea™ (DT) is an anti-diabetic alternative medicine in some Asian countries. The main constituent of DT is black tea originating from Camellia sinensis that is supplemented by 12 other medicinal plants. Black tea contains a large amount of the flavonoids catechins especially epigallocatechin gallate (EGCG) which has anti-inflammatory and antioxidative capacity. This study was undertaken to evaluate the possible effects of DT intake on inflammatory cytokines, regulatory T cells (Tregs) and metabolic biomarkers in T2DM. MATERIALS AND METHODS: The study included 50 patients with T2DM. The patients had received 3 cups (600ml) of DT extract or placebo (PL) extract per day during a period of 12 weeks. Intracellular cytokine expression in peripheral blood mononuclear cell (PBMC) as well as the glycemic and lipid profiles were measured at baseline and after the treatment period. The active constituents of the medicinal plants included in DT were investigated by gas chromatography-mass spectrometry (GC/MS). RESULTS: Ingestion of DT suppressed CD4+ T cell expression of IL-1ß and Il-8 (p<0.05) and up-regulated the expression of IL-10 and the Treg/IL-17 ratio (p<0.05) which was not shown in PL. A significant decrease in HbA1c and LDL was observed at the end of the study period (p<0.05) in DT. The GC/MS analyses of DT indicated the presence of lupeol, ß-Amyrin and ß-sitosterol. Also analyses of individual herbs showed the presence of higher levels of lupeol and ß-Amyrin in Nuga Ficus bengalensis and ß-sitosterol in the Attikka Ficus racemosa, indicating that the active ingredients of DT are concentrated in these two herbs. CONCLUSION: The present study provides evidence that DT has hypoglycemic and antihyperlipidemic properties. Interestingly, DT has anti-inflammatory effects. These properties are attributed to the flavonoids, triterpenes and phytosterol contents of the tea. We suggest that DT protects against diabetes complications in the long term.


Subject(s)
Beverages/analysis , Cytokines/metabolism , Diabetes Mellitus, Type 2/metabolism , Inflammation/drug therapy , Plant Extracts/pharmacology , Biomarkers , Cytokines/genetics , Double-Blind Method , Female , Gene Expression Regulation/drug effects , Humans , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/therapeutic use , Inflammation/metabolism , Male , Plant Extracts/chemistry , Plants, Medicinal
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