Cardiac Muscle Injury and Echocardiographic Plus Electrocardiographic Findings in Patients With 2019 Novel Coronavirus (COVID-19): A Retrospective Cohort Study.

Background: Myocardial injury has been described in coronavirus-2019 (COVID-19). Few studies have reported cardiovascular imaging data with transthoracic echocardiography (TTE) and electrocardiography (ECG) findings in COVID-19 patients, and their correlation with mortality. Methods: We conducted a retrospective cohort study that included COVID-19 patients from March 2020 through February 2021 who had TTE and ECG during hospital admission. Myocardial injury was defined by an elevated high-sensitivity troponin T level > 20 ng/L. Bivariate analysis was used to compare patients with myocardial injury and those without. Multivariate logistic regression analysis was performed to identify the variables associated with mortality. Results: A total of 438 patients were included. The mean age was 62.1 ± 14.9 years, and 58.9% were male. A total of 149 patients died, with a mortality rate of 34%. A total of 260 patients (59.4%) had myocardial injury. The average left ventricular ejection fraction was 59.8% ± 11.2%, with 30 patients (6.8%) having an ejection fraction of < 40%. Patients with myocardial injury had higher mortality than those without (P < 0.05, χ2 test). A multiple regression analysis model indicated that age, race and/or ethnicity, the development of acute respiratory distress syndrome, shock, the need for vasopressors, mechanical ventilation, and hemodialysis were the variables significantly associated with mortality. Conclusion: COVID-19 patients with myocardial injury had higher mortality than those without. Age, race and/or ethnicity, acute respiratory distress syndrome, shock, the need for vasopressors, mechanical ventilation, and hemodialysis were the clinical variables associated with mortality. The TEE and ECG variables studied were not significantly associated with mortality.

Contexte: Des atteintes myocardiques ont été décrites en présence d'une infection par le coronavirus 2019 (COVID-19). Quelques études ont rapporté des données d'imagerie cardiovasculaire obtenues par échocardiographie transthoracique (ETT) et électrocardiographie (ECG) chez des patients atteints de la COVID-19, et leur corrélation avec la mortalité. Méthodologie: Nous avons mené une étude de cohorte rétrospective comprenant des patients atteints de la COVID-19 entre mars 2020 et février 2021 qui ont été soumis à une ETT ou à une ECG pendant leur hospitalisation. L'atteinte myocardique était définie comme un taux élevé de troponine T de haute sensibilité > 20 ng/L. Une analyse à deux variables a été utilisée pour comparer les patients présentant une atteinte myocardique et ceux qui n'en présentaient pas. Une analyse de régression logistique à multiples variables a été menée pour définir les variables qui étaient associées à la mortalité. Résultats: L'étude comptait un total de 438 patients. L'âge moyen était de 62,1 ± 14,9 ans; 58,9 % étaient des hommes. Un total de 149 patients sont décédés, soit un taux de mortalité de 34 %. Un total de 260 patients (59,4 %) présentaient une atteinte myocardique. La fraction d'éjection ventriculaire gauche moyenne était de 59,8 % ± 11,2 %, alors que 30 patients (6,8 %) affichaient une fraction d'éjection inférieure à 40 %. Le taux de mortalité était plus élevé chez les patients qui présentaient une atteinte myocardique que chez ceux qui n'en présentaient pas (p < 0,05, test χ2). Selon un modèle d'analyse de régression multiple, l'âge, la race et/ou l'ethnicité, l'apparition du syndrome de détresse respiratoire aiguë, l'état de choc, le besoin de vasopresseurs, la ventilation artificielle et l'hémodialyse étaient les variables fortement liées à la mortalité. Conclusion: Parmi les patients atteints de la COVID-19, la mortalité était plus élevée chez ceux qui présentaient une atteinte myocardique que chez ceux qui n'en présentaient pas. L'âge, la race et/ou l'ethnicité, le syndrome de détresse respiratoire aiguë, l'état de choc, le besoin de vasopresseurs, la ventilation artificielle et l'hémodialyse étaient les variables cliniques liées à la mortalité. Les variables d'ETT et d'ECG étudiées n'avaient pas de lien important avec la mortalité.

Optimization Conditions to Obtain Cationic Polyacrylamide Emulsion Copolymers with Desired Cationic Degree for Different Wastewater Treatments.

The synthesis of cationic polyacrylamides (CPAMs) with the desired cationic degree and molecular weight is essential for various industries, including wastewater treatment, mining, paper, cosmetic chemistry, and others. Previous studies have already demonstrated methods to optimize synthesis conditions to obtain high-molecular-weight CPAM emulsions and the effects of cationic degrees on flocculation processes. However, the optimization of input parameters to obtain CPAMs with the desired cationic degrees has not been discussed. Traditional optimization methods are time-consuming and costly when it comes to on-site CPAM production because the input parameters of CPAM synthesis are optimized using single-factor experiments. In this study, we utilized the response surface methodology to optimize the synthesis conditions, specifically the monomer concentration, the content of the cationic monomer, and the content of the initiator, to obtain CPAMs with the desired cationic degrees. This approach overcomes the drawbacks of traditional optimization methods. We successfully synthesized three CPAM emulsions with a wide range of cationic degrees: low (21.85%), medium (40.25%), and high (71.17%) levels of cationic degree. The optimized conditions for these CPAMs were as follows: monomer concentration of 25%, content of monomer cation of 22.5%, 44.41%, and 77.61%, respectively, and initiator content of 0.475%, 0.48%, and 0.59%, respectively. The developed models can be utilized to quickly optimize conditions for synthesizing CPAM emulsions with different cationic degrees to meet the demands of wastewater treatment applications. The synthesized CPAM products performed effectively in wastewater treatment, with the treated wastewater meeting the technical regulation parameters. 1H-NMR, FTIR, SEM, BET, dynamic light scattering, and gel permeation chromatography were employed to confirm the structure and surface of the polymers.

Dioctyl Phthalate-Modified Graphene Nanoplatelets: An Effective Additive for Enhanced Mechanical Properties of Natural Rubber.

Graphene has been extensively considered an ideal additive to improve the mechanical properties of many composite materials, including rubbers, because of its novel strength, high surface area, and remarkable thermal and electron conductivity. However, the pristine graphene shows low dispersibility in the rubber matrix resulting in only slightly enhanced mechanical properties of the rubber composite. In this work, graphene nanoplatelets (GNPs) were modified with dioctyl phthalate (DOP) to improve the dispersibility of the graphene in the natural rubber (NR). The distribution of the DOP-modified GNPs in the NR matrix was investigated using scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The effect of the modified GNPs' contents on the mechanical properties of the GNPs/NR composite was studied in detail. The results showed that the abrasion resistance of the graphene-reinforced rubber composite significantly improved by 10 times compared to that of the rubber without graphene (from 0.3 to 0.03 g/cycle without and with addition of the 0.3 phr modified GNPs). The addition of the modified GNPs also improved the shear and tensile strength of the rubber composite. The tensile strength and shear strength of the NR/GNPs composite with a GNPs loading of 0.3 phr were determined to be 23.63 MPa and 42.69 N/mm, respectively. Even the presence of the graphene reduced the other mechanical properties such as Shore hardness, elongation at break, and residual elongation; however, these reductions were negligible, which still makes the modified GNPs significant as an effective additive for the natural rubber in applications requiring high abrasion resistance.

Optimizing the Conditions of Cationic Polyacrylamide Inverse Emulsion Synthesis Reaction to Obtain High-Molecular-Weight Polymers.

Cationic polyacrylamide (CPAM) emulsifier is widely applied in the wastewater treatment industry, mining industry, paper industry, cosmetic chemistry, etc. However, optimization of input parameters in the synthesis of CPAM by using the traditional approach (i.e., changing one factor while leaving the others fixed at a particular set of conditions) would require a long time and a high cost of input materials. Onsite mass production of CPAM requires fast optimization of input parameters (i.e., stirring speed, reaction temperature and time, the amount of initiator, etc.) to minimize the production cost of specific-molecular-weight CPAM. Therefore, in this study, we synthesized CPAM using reverse emulsion copolymerization, and proposed response surface models for predicting the average molecular weight and reaction yield based on those input parameters. This study offers a time-saving tool for onsite mass production of specific-molecular-weight CPAM. Based on our response surface models, we obtained the optimal conditions for the synthesis of CPAM emulsions, which yielded medium-molecular-weight polymers and high conversion, with a reaction temperature of 60-62 °C, stirring speed of 2500-2600 rpm, and reaction time of 7 h. Quadratic models showed a good fit for predicting molecular weight (Adj.R2 = 0.9888, coefficient of variation = 2.08%) and reaction yield (Adj.R2 = 0.9982, coefficient of variation = 0.50%). The models suggested by our study would benefit the cost-minimization of CPAM mass production, where one could find optimal conditions for synthesizing different molecular weights of CPAM more quickly than via the traditional approach.

COVID-19 and the cardiovascular system: A review of current data, summary of best practices, outline of controversies, and illustrative case reports.

As the severe acute respiratory syndrome coronavirus 2 virus pandemic continues to grow globally, an association is apparent between patients with underlying cardiovascular disease comorbidities and the risk of developing severe COVID-19. Furthermore, there are potential cardiac manifestations of severe acute respiratory syndrome coronavirus 2 including myocyte injury, ventricular dysfunction, coagulopathy, and electrophysiologic abnormalities. Balancing management of the infection and treatment of underlying cardiovascular disease requires further study. Addressing the increasing reports of health care worker exposure and deaths remains paramount. This review summarizes the most contemporary literature on the relationship of the cardiovascular system and COVID-19 and society statements with relevance to protection of health care workers, and provides illustrative case reports in this context.

Development of a Solar-Powered IoT-Based Instrument for Automatic Measurement of Water Clarity.

Water clarity is the most common indicator of water quality. The purpose of the study was to develop an instrument which can automatically measure water clarity in place of manual measurement by Secchi disk. The instrument is suspended by buoys at the water surface and uses solar energy to measure the light intensity of LED bulbs after passing through a water column; the result is then converted to Secchi depth by using a regression function. Measurement data are stored in a cloud server so that mobile users can access via an Internet connection. Three experiments were conducted to examine the instrument performance: (i) to ensure light intensity of the LED bulbs is strong enough to pass through the water column; (ii) to determine the regression relationship between the measured light intensity of the instrument and Secchi depth; and (iii) to evaluate the coefficient of variation (CV) of the measured water clarity when using our instrument and a conventional Secchi disk. Experiment results show that the measured values of light intensity are stable with the average CV = 5.25%. Moreover, although there are slight differences between the Secchi depth measured by our instrument and those measured by Secchi disk, the measurements by our instrument can efficiently replace the measurements by conventional Secchi disk, which can be affected by weather conditions as well as by human subjectivity.