Nonstatistical Unimolecular Decay of the CH2OO Criegee Intermediate in the Tunneling Regime.

Unimolecular decay of the formaldehyde oxide (CH2OO) Criegee intermediate proceeds via a 1,3 ring-closure pathway to dioxirane and subsequent rearrangement and/or dissociation to many products including hydroxyl (OH) radicals that are detected. Vibrational activation of jet-cooled CH2OO with two quanta of CH stretch (17-18 kcal mol-1) leads to unimolecular decay at an energy significantly below the transition state barrier of 19.46 ± 0.25 kcal mol-1, refined utilizing a high-level electronic structure method HEAT-345(Q)Λ. The observed unimolecular decay rate of 1.6 ± 0.4 × 106 s-1 is 2 orders of magnitude slower than that predicted by statistical unimolecular reaction theory using several different models for quantum mechanical tunneling. The nonstatistical behavior originates from excitation of a CH stretch vibration that is orthogonal to the heavy atom motions along the reaction coordinate and slow intramolecular vibrational energy redistribution due to the sparse density of states.

The impact of COVID-19 and other factors on the usage status of the biologic drug therapies for rheumatoid arthritis: A study from Vietnam.

OBJECTIVES: To describe the status of using biological Disease Modifying Anti Rheumatic Drugs (bDMARDs) to treat rheumatoid arthritis (RA) and related factors. In addition, the study determined the impact of COVID-19 on the usage of bDMARDs. METHODS: This is a cross-sectional study and included 219 RA patients over 18 years old. The Kaplan-Meier method and the log-rank test (p<0.05) were used to estimate the retention time and compare between different times. Cox regression analysis was used to determine the factors affecting the retention time of biological drugs (p<0.05). RESULTS: Out of 1967 courses of treatment, there were 149 (7.6%) drug discontinuations, 760 (38.6%) doses extensions and 64 (3.3%) drug switch. Moderate disease level and choosing tumor necrosis factor (TNF) inhibitors initially were associated with retention time of COVID-19. Drug discontinuations and dose extensions increased after COVID-19 emergence. The retention time during COVID-19 was significantly different from that of pre-COVID-19. Gender, type of first-used bDMARD, conventional synthetic DMARDs (csDMARDs) and corticoid usage status, disease activity levels were associated with retention time. CONCLUSION: The presence of COVID-19 has a significant effect on usage status of the biologic drug. Further longitudinal studies are needed to clarify the relationship between COVID-19 and drug usage as well as related factors.

The impact of COVID-19 and other factors on the usage status of the biologic drug therapies for rheumatoid arthritis: A study from Vietnam / El impacto de COVID-19 y otros factores en el estado de uso de las terapias farmacológicas biológicas para la artritis reumatoide: un estudio de Vietnam

Objectives: To describe the status of using biological Disease Modifying Anti Rheumatic Drugs (bDMARDs) to treat rheumatoid arthritis (RA) and related factors. In addition, the study determined the impact of COVID-19 on the usage of bDMARDs. Methods: This is a cross-sectional study and included 219 RA patients over 18 years old. The Kaplan–Meier method and the log-rank test (p<0.05) were used to estimate the retention time and compare between different times. Cox regression analysis was used to determine the factors affecting the retention time of biological drugs (p<0.05). Results: Out of 1967 courses of treatment, there were 149 (7.6%) drug discontinuations, 760 (38.6%) doses extensions and 64 (3.3%) drug switch. Moderate disease level and choosing tumor necrosis factor (TNF) inhibitors initially were associated with retention time of COVID-19. Drug discontinuations and dose extensions increased after COVID-19 emergence. The retention time during COVID-19 was significantly different from that of pre-COVID-19. Gender, type of first-used bDMARD, conventional synthetic DMARDs (csDMARDs) and corticoid usage status, disease activity levels were associated with retention time. Conclusion: The presence of COVID-19 has a significant effect on usage status of the biologic drug. Further longitudinal studies are needed to clarify the relationship between COVID-19 and drug usage as well as related factors.(AU)

Objetivos: Describir el estado del uso de fármacos antirreumáticos modificadores de la enfermedad biológica (bDMARD) para tratar la artritis reumatoide (AR) y los factores relacionados. Además, el estudio determinó el impacto de COVID-19 en el uso de bDMARD. Métodos: Este es un estudio transversal que incluyó a 219 pacientes con AR mayores de 18 años. El método Kaplan-Meier y la prueba Log-rank (p<0,05) se usaron para estimar el tiempo de retención y compararlo entre diferentes tiempos. El análisis de regresión de Cox se utilizó para determinar los factores que afectan el tiempo de retención de los medicamentos biológicos (p<0,05). Resultados: De 1.967 cursos de tratamiento, hubo 149 (7,6%) interrupciones del fármaco, 760 (38,6%) extensiones de dosis y 64 (3,3%) cambios de fármaco. Nivel de enfermedad moderado y elección del factor de necrosis tumoral (TNF) inhibidores inicialmente se asociaron con el tiempo de retención de COVID-19. Las discontinuaciones de los medicamentos y las extensiones de las dosis aumentaron después de la aparición de COVID-19. El tiempo de retención durante COVID-19 fue significativamente diferente del pre-COVID-19. Género, tipo de bDMARD de primer uso, convencional DMARD sintéticos (csDMARDs) y el estado de uso de corticoides, los niveles de actividad de la enfermedad se asociaron con el tiempo de retención. Conclusión: La presencia de COVID-19 tiene un efecto significativo en el estado de uso del medicamento biológico. Se necesitan más estudios longitudinales para aclarar la relación entre COVID-19 y el uso de fármacos, así como los factores relacionados.(AU)

Methanediol from cloud-processed formaldehyde is only a minor source of atmospheric formic acid.

Atmospheric formic acid is severely underpredicted by models. A recent study proposed that this discrepancy can be resolved by abundant formic acid production from the reaction (1) between hydroxyl radical and methanediol derived from in-cloud formaldehyde processing and provided a chamber-experiment-derived rate constant, k1 = 7.5 × 10-12 cm3 s-1. High-level accuracy coupled cluster calculations in combination with E,J-resolved two-dimensional master equation analyses yield k1 = (2.4 ± 0.5) × 10-12 cm3 s-1 for relevant atmospheric conditions (T = 260-310 K and P = 0-1 atm). We attribute this significant discrepancy to HCOOH formation from other molecules in the chamber experiments. More importantly, we show that reversible aqueous processes result indirectly in the equilibration on a 10 min. time scale of the gas-phase reaction [Formula: see text] (2) with a HOCH2OH to HCHO ratio of only ca. 2%. Although HOCH2OH outgassing upon cloud evaporation typically increases this ratio by a factor of 1.5-5, as determined by numerical simulations, its in-cloud reprocessing is shown using a global model to strongly limit the gas-phase sink and the resulting production of formic acid. Based on the combined findings in this work, we derive a range of 1.2-8.5 Tg/y for the global HCOOH production from cloud-derived HOCH2OH reacting with OH. The best estimate, 3.3 Tg/y, is about 30 times less than recently reported. The theoretical equilibrium constant Keq (2) determined in this work also allows us to estimate the Henry's law constant of methanediol (8.1 × 105 M atm-1 at 280 K).

Willingness and attitudes of parents towards COVID-19 vaccines for children in Vietnam.

BACKGROUND: With an increasing need for COVID-19 vaccination around the globe, we aim to investigate willingness and attitudes of parents regarding COVID-19 vaccines for children in Vietnam. METHOD: A 24-item online survey was conducted among 602 parents and legal guardians of children under 18 years of age. RESULTS: There were 82.6% of parents willing to vaccinate their children. The principal reasons for willingness were: the need for vaccination to control the COVID-19 pandemic and to reduce the risk of SARS-CoV-2 transmission when children return to school. The most common reason for refusing COVID-19 vaccine was the concern about vaccine side effects in children (73.3%), followed by perceived lack of scientific research on COVID-19 vaccines in children (31.4%). The main associated factors with increased willingness of parents towards childhood COVID-19 vaccine were: willingness to allow children to participate in a clinical vaccine trial (aOR = 3.58); possible increase in COVID-19-related mortality (aOR = 3.69); and positive media information regarding COVID-19 vaccine (aOR = 2.04). Noteworthy, higher educational status of parents was associated with decreased willingness for childhood COVID-19 vaccine (aOR = 0.26). CONCLUSION: Understanding reasons of parents to accept childhood COVID-19 vaccines will help future plans in COVID-19 vaccination program. A larger sample size study at a national level is needed to verify the results.

Frizzled receptors and SFRP5 in lipid metabolism: Current findings and potential applications.

Lipid metabolism plays a very important role as the central metabolic process of the body. Lipid metabolism interruptions may cause many chronic diseases, for example, non-alcoholic fatty liver disease (NAFLD), diabetes, and obesity. Secreted Frizzled Related Protein 5 (SFRP5) and Frizzled receptors (FZD) are two newly discovered adipokines that are involved in lipid metabolism as well as lipogenesis. Both of these adipokines affect lipid metabolism and adipogenesis through three WNT signaling pathways (WNTSP): WNT/ß-catenin, WNT/Ca2+, and WNT/JNK. FZD consists of 10 species, which have a cysteine-rich domain (CRD) to bind to the WNT protein for signal transduction. Depending on the type of ligand or co-receptor, they can stimulate or inhibit adipogenesis. In lipid metabolism, they play a role in recognizing fatty acids. In obesity, gene expression of the WNT/FZD receptors is significantly increased. In contrast, SFPR5 serves as an antagonist that can compete with FZD for inhibition of WNTSP. It is believed to have anti-inflammatory potential in obesity and diseases related to abnormal lipid metabolism. In these cases, the expression of SFRP5 is found to be very low leading to the promoted production of proinflammatory cytokines (PICS). Some methods that include using recombinant SFRP5 to improve non-alcoholic steatohepatitis (NASH), using secreted Ly-6/uPAR-related protein 1 (Slurp1) to regulate fat accumulation in the liver through SFRP5, and dietary and lifestyle interventions to improve overweight/obesity have been studied. However, understandings of the molecular mechanisms of these two adipokines and their interactions are very limited. Therefore, more in-depth studies are needed in the future.

High-accuracy first-principles-based rate coefficients for the reaction of OH and CH3OOH.

The ˙OH-initiated oxidation of methyl hydroperoxide, which plays an important role in the atmospheric chemistry of methane, was theoretically characterized using high-accuracy composite amHEAT-345(Q) coupled-cluster calculations followed by a two-dimensional E,J resolved master equation analysis. The reaction is found to proceed through two distinct hydrogen-bonded pre-reactive complexes leading to two product channels, in accord with the experimental observations: (i) ˙OH + CH3OOH → CH3OO˙ + H2O with a yield of 0.8 ± 0.1, and (ii) ˙OH + CH3OOH → HCHO + ˙OH + H2O with a yield of 0.2 ± 0.1. The calculated reaction enthalpies are within 0.2 kcal mol-1 of the benchmark ATcT values. Overall thermal rate coefficients obtained from first principles are found to be in the low-pressure limit at atmospheric pressure; the total rate coefficient can be expressed over the T = 200-450 K range as k(T) = 5.0 × 10-12 × T-0.152 × exp(287/T) cm3 s-1, strongly supporting the experimental results of Vaghjiani and Ravishankara (J. Phys. Chem. 1989, 93, 1948), with which this expression agrees within ca. 15%. The current results show that (i) is the principal reaction channel and support the view that, due to its inherently fast transformations, CH3OOH is an important redistribution species for HOx˙ radicals in the Earth's atmosphere.

Mechanism, thermochemistry, and kinetics of the reversible reactions: C2H3 + H2 ⇌ C2H4 + H ⇌ C2H5.

High-level coupled cluster theory, in conjunction with Active Thermochemical Tables (ATcT) and E,J-resolved master equation calculations, was used in a study of the title reactions, which play an important role in the combustion of hydrocarbons. In the set of radical/radical reactions leading to soot formation in flames, the addition of H-atoms to alkenes is likely a common reaction, triggering the isomerization of complex hydrocarbons to aromatics. The heats of formation of C2H3, C2H4, and C2H5 are established to be 301.26 ± 0.30 at 0 K (297.22 ± 0.30 at 298 K), 60.89 ± 0.11 (52.38 ± 0.11), and 131.38 ± 0.22 (120.63 ± 0.22) kJ mol-1, respectively. The calculated rate constants from first principles agree well with experiments where they are available. Under conditions typical of high temperature combustion - where experimental work is very challenging with a consequent dearth of accurate data - we provide high-level theoretical results for kinetic modeling.

Reaction of Methylidyne with Ethane: The C-C Insertion Is Unimportant.

High-accuracy coupled-cluster calculations in combination with the E,J-resolved master-equation analysis are used to study the reaction mechanism and kinetics of methylidyne with ethane. This reaction plays an important role in the combustion of hydrocarbon fuels and in interstellar chemistry. Two distinct mechanisms, the C-C and the C-H insertions of CH in C2H6, are characterized. The C-C insertion pathway is identified to have a large barrier of 34.5 kcal mol-1 and hence plays no significant role in kinetics. The C-H insertion pathway is found to have no barrier, leading to a highly vibrationally excited n-C3H7 radical, which rapidly dissociates (within 50 ps) to yield CH3 + C2H4 and H + C3H6 in a roughly 7:3 ratio. These findings are in good agreement with an experimental result that indicates that about 20% of the reaction goes to H + C3H6. The reaction of the electronically excited quartet state of the CH radical with C2H6 is examined for the first time and found to proceed as a direct H-abstraction via a small barrier of 0.4 kcal mol-1 to yield triplet CH2 and C2H5. The reaction on the quartet state surface is negligibly slow at low temperatures characteristic of interstellar environments but becomes important at high combustion temperatures.

Probing the Exit Channel of the OH + CH3OH → H2O + CH3O Reaction by Photodetachment of CH3O-(H2O).

Transition state dynamics of bimolecular reactions can be probed by photodetachment of a precursor anion when the Franck-Condon region of the corresponding neutral potential energy surface is near a saddle point. In this study, photodetachment of anions at m/z = 49 enabled investigation of the exit channel of the OH + CH3OH → H2O + CH3O reaction using photoelectron-photofragment coincidence spectroscopy. High-level coupled-cluster calculations of the stationary points on the anion surface show that the methoxide-water cluster CH3O-(H2O) is the stable minimum on the anion surface. Photodetachment at a 3.20 eV photon energy leads to long-lived H2O(CH3O) complexes and H2O + CH3O products consistent with both direct dissociative photodetachment and resonance mediated processes on the neutral surface. The partitioning of total kinetic energy in the system indicates that water stretch and bend excitation is induced in dissociative photodetachment and evidence for long-lived complexes consistent with vibrational Feshbach resonances is reported.

Transmission of SARS-CoV-2 infections and exposure in surfaces, points and wastewaters: A global one health perspective.

The persistence of SARS-CoV-2 or its RNA on surfaces, points, or wastewaters may increase the risk of transmission of this virus. Therefore, we conducted this review to discuss the places and surfaces with the highest potential for infection and spread of the SARS-CoV-2 virus. Several common and public areas, hospitals, elevators, public transport, local markets, and surfaces such as public toilets, door handles, untreated and treated wastewaters, wastewater plants, and public washrooms are also considered major points for spreading of SARS-CoV-2. Highly contaminated surfaces or places often have materials or contain items made of materials on which the SARS-CoV-2 virus can persist (e.g., metal, wood, and plastic). For example, SARS-CoV-2 can exist up to 4 days on doorknobs made by those materials. For public places such as public transports, elevators, and local markets, crowding and enclosed spaces are major source for transmission. Several measures such as using copper alloy surfaces instead of metal surfaces, disinfectants, and suitable personal protective equipment have been suggested. Our research could be the basis to help develop studies on the existence and transmissibility of SARS-CoV-2 as well as its RNA to take measures to prevent and limit the harmful effects of COVID-19 pandemic.

COVID-19 and environmental health: A systematic analysis for the global burden of biomedical waste by this epidemic.

Since the beginning of this outbreak, much evidence stated that the climb in the amount of biomedical waste harmed human health and had adverse effects on the environment. With the increase of cases of COVID-19 all around the globe, the amount of biomedical waste was also constantly rising. Also, many solutions regarding either reducing or recycling biomedical waste. However, the potential global burden of biomedical waste during this pandemic was not yet been analyzed. Herein, we perform a systematic review of literature on these modalities, including mentioning types of biomedical waste, the effect on health, the environment, and methods of handling biomedical waste during this pandemic. A total of 3551 published papers were identified by two databases. In the end, 15 references were selected for this systematic analysis. Most of the included studies focus on research on the impact of medical waste caused by the COVID-19 pandemic on the environment. The total biomedical waste during the COVID-19 pandemic was approximately 16,649.48 tons/day. Most publications agreed that the amount of waste has also increased due to the rapidly rising number of COVID-19 patients. In 15 articles, we identified 2 mentioning the COVID-19 biomedical waste on health. 9 out of 15 gave out the context related to the solution of BMW by COVID-19. More studies, including meta-analyses, are recommended to shed more light on the effects of medical waste on environmental health during the COVID-19 pandemic.

Thermal Decomposition of CH3O: A Curious Case of Pressure-Dependent Tunneling Effects.

The thermal unimolecular decomposition of a methoxy radical (CH3O), a key intermediate in the combustion of methane, methanol, and other hydrocarbons, was studied using high-level coupled-cluster calculations, followed by E,J-resolved master equation analyses. The experimental results available for a wide range of temperature and pressure are in striking agreement with the calculations. In line with a previous theoretical study that used a one-dimensional master equation, the tunneling correction is found to exhibit a marked pressure dependence, being the largest at low pressure. This curious effect on the tunneling enhancement also affects the calculated kinetic isotope effect, which falls initially with pressure but is predicted to rise again at high pressures. These findings serve to reconcile a set of conflicting results regarding the importance of tunneling in this prototype unimolecular reaction and also motivate further experimental investigation. This study also exemplifies how changes in the energy redistribution due to collisions manifest in the tunneling rates.

The CH(X2Π) + H2O reaction: two transition state kinetics.

The reaction of ground state methylidyne (CH) with water vapor (H2O) is theoretically re-investigated using high-level coupled cluster computations in combination with semi-classical transition state theory (SCTST) and two-dimensional master equation simulations. Insertion of CH into a H-O bond of H2O over a submerged barrier via a well-skipping mechanism yielding solely H and CH2O is characterized. The reaction kinetics is effectively determined by the formation of a pre-reaction van der Waals complex (PRC, HC-OH2) and its subsequent isomerization to activated CH2OH in competition with PRC re-dissociation. The tunneling effects are found to be minor, while variational effects in the PRC → CH2OH step are negligible. The calculated rate coefficient k(T) is nearly pressure-independent, but strongly depends on temperature with pronounced down-up behavior: a high value of 2 × 10-10 cm3 s-1 at 50 K, followed by a fairly steep decrease down to 8 × 10-12 cm3 s-1 at 900 K, but increasing again to 5 × 10-11 cm3 s-1 at 3500 K. Over the T-range of this work, k(T) can be expressed as: k(T, P = 0) = 2.31 × 10-11 (T/300 K)-1.615 exp(-38.45/T) cm3 s-1 for T = 50-400 K k(T, P = 0) = 1.15 × 10-12 (T/300 K)0.8637 exp(892.6/T) cm3 s-1 for T = 400-1000 K k(T, P = 0) = 4.57 × 10-15 (T/300 K)3.375 exp(3477.4/T) cm3 s-1 for T = 1000-3500 K.

Pressure-Dependent Rate Constant Caused by Tunneling Effects: OH + HNO3 as an Example.

Tunneling effects on chemical reactions are well-known and have been unambiguously demonstrated by processes that involve the motion of hydrogen atoms at low temperature. However, the process by which tunneling effects cause a falloff curve (i.e., how reaction rate constants depend on pressure) has apparently not been previously documented. This work points out that falloff curves can indeed be caused by tunneling and explains the effect in simple terms. This is an interesting feature of quantum tunneling, which can appear in low temperature chemistry (such as in atmospheric or interstellar environments). In this Letter, we use high-level coupled-cluster calculations in combination with master-equation methods on the well-studied reaction of OH with HNO3, which plays an important role in the upper troposphere and lower stratosphere. Our results in combination with available experimental data clearly demonstrate that the tunneling correction depends on not just temperature, but also pressure.