•Dy addition reduces Ni crystallite size and improve its dispersion on Ni/SiC-SiO2.•0.5 %Dy-10 %Ni/SiC-SiO2 achieves 100 % CH4 selectivity and 73.9 % CO2 conversion at 350 °C.•Microwave heating ...outperforms electric, yielding higher CO2 conversion.•Extreme SiC dilution hampers CO2 conversion and CH4 selectivity in both reactors.•Carbon formation in the microwave reactor quantified at only 0.0099 mgC/gcat/h.
In this work, Dy-promoted Ni/SiC-SiO2 catalysts with varied Dy loadings (0–1 %) were developed using the wet impregnation method and evaluated for their effectiveness in CO2 methanation. The characterization results reveal that Dy addition can reduce the Ni crystallite size, enhance the dispersion of active phase and increase the catalyst’s reducibility. Among the prepared catalysts, the 0.5 %Dy-10 %Ni/SiC-SiO2 demonstrated the highest CH4 selectivity (100 %) and CO2 conversion (73.9 %) at 350 °C owing to its highest basic sites and H2 chemisorption capacity. The performance of this Dy-promoted catalyst diluted with different amounts of SiC, which was employed as a microwave susceptor and high thermal conductive dilution material, was also investigated in both microwave and electric reactor. Microwave heating leads to higher CO2 conversion compared to electric heating, regardless of reaction temperature and dilution factor due to selective heating and the random occurrence of hot spots, which are usually considered as micro-plasmas in the catalyst bed. However, further increase quantity of SiC decreased both CO2 conversion and CH4 selectivity regardless of heating method. This may be attributed to the appearance of extreme overheating and the absence of gentle overheating with increased amount of SiC in the microwave and electric reactors, respectively. The temperature-programmed oxidation results demonstrated that carbon deposition on the 0.5 %Dy-10 %Ni/SiC-SiO2 catalyst during 30 h of reaction can be significantly suppressed by microwave.
The self-regeneration of Ni-based catalysts has been considered as a promising approach to maintain not only a continuous but also economical process. However, the effect of catalyst nature, ...operating temperature, amount and types of carbon deposits on the effectiveness of the in-situ regeneration is still not well-investigated. Therefore, in this work, the self-regeneration ability of the undoped and Dy-doped Ni/SiO2 catalysts, which were prepared by the same impregnation method, were examined in the dry reforming of methanol. The physicochemical properties of the fresh and spent catalysts were analyzed by various techniques such as X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), oxygen temperature-programmed desorption (O2-TPD), transmission electron microscopy (TEM), N2-BET isothermal adsorption. The nature and chemical reactivity of coke deposits formed during dry reforming at various temperatures (550, 600, and 650 °C) and the regeneration possibility of used catalysts through CO2 gasification at these temperatures were investigated by the in-situ temperature-programmed gasification by CO2 (TPCO2). The Dy additive significantly improves the dispersion of the nickel active sites of Ni/SiO2 catalyst, as demonstrated by the decreased Ni crystal size as well as the increased specific surface area and reduction degree of the catalyst. Furthermore, Dy promotion increases the quantity of oxygen vacancies and the nature of oxygen species, thereby improving the catalyst activity and stability. Specifically, methanol conversion dropped from 93% to 96%–61% and 31% for undoped Ni/SiO2 at 600 °C and 650 °C, respectively and from about 99% to 87% (at 600 °C) and 52% (at 650 °C) for Dy-doped catalyst.
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•Self-regeneration ability of Ni-catalysts for CO2 reforming of methanol was studied.•Dy additive significantly improves the performance of Ni/SiO2 catalyst.•Carbon deposits on Dy–Ni/SiO2 were completely removed by CO2 reactant at 600°C.•Activity of Dy–Ni/SiO2 was fully restored after 60 min of turning off methanol.
Extracorporeal membrane oxygenation (ECMO) support can be life-saving in critically ill COVID-19 patients. However, there are many complications associated with this procedure, including ...Heparin-induced thrombocytopenia (HIT.) Despite its rarity in ECMO cases, HIT can lead to devastating consequences and is difficult to manage.
In this report, we present a case of a COVID-19 patient on ECMO support who was diagnosed with HIT and required intensive treatment. Initially, HIT was only suspected due to newly-developed thrombocytopenia and oxygenator dysfunction, with thrombi observed later. Regarding his treatment, since there was no recommended replacement to heparin available to us at the time of diagnosis, we decided to use rivaroxaban temporarily. No adverse events were recorded during that period. The patient was able to make a full recovery.
HIT may jeopardize patient's care during ECMO. As COVID-19 may bring about a surge in the number of patients requiring ECMO support, we need consented guidance to optimize treatment in this specific situation.
Patients with immune thrombocytopenic purpura (ITP) often present with a severe reduction in platelet counts and suffer from an increased risk of bleeding. However, platelet counts do not accurately ...predict bleeding risk in these patients.
We thereby conducted a case series prospective study to compare the ability to predict hemorrhage in ITP patients between platelet counts and various rotational thromboelastometry (ROTEM) parameters.
The inclusion criteria for patients diagnosed with acute, persistent, and chronic ITP were platelet counts of <30 × 109/L and no clinically significant bleeding (grade ≥ 2 according to the WHO Bleeding Scale) at the beginning of the study. After 24 hours of follow-up, of the 45 enrolled patients, 14 (31.1%) experienced clinically significant bleeding. The mean platelet counts of patients with and without clinically significant bleeding were not statistically different (p = .09). However, the mean EXTEM maximum clot firmness (MCF), EXTEM A10, EXTEM area under the curve (AUC), and platelet maximum clot elasticity (MCE) values of the two groups were statistically different (p < .05). There was also a significant difference in IPF values between these two groups (p < .05.)
Results obtained from this preliminary study demonstrate that ROTEM parameters might be useful in predicting factors for hemorrhage in ITP patients. Future studies with a larger sample size is warranted to confirm our findings, which will allow prompt and effective bleeding management in ITP patients.
Mutation and reassortment of highly pathogenic avian influenza A(H5N1) viruses at the animal–human interface remain a major concern for emergence of viruses with pandemic potential. To understand the ...relationship of H5N1 viruses circulating in poultry and those isolated from humans, comprehensive phylogenetic and molecular analyses of viruses collected from both hosts in Vietnam between 2003 and 2010 were performed. We examined the temporal and spatial distribution of human cases relative to H5N1 poultry outbreaks and characterized the genetic lineages and amino acid substitutions in each gene segment identified in humans relative to closely related viruses from avian hosts. Six hemagglutinin clades and 8 genotypes were identified in humans, all of which were initially identified in poultry. Several amino acid mutations throughout the genomes of viruses isolated from humans were identified, indicating the potential for poultry viruses infecting humans to rapidly acquire molecular markers associated with mammalian adaptation and antiviral resistance.
The catalytic methanation of carbon dioxide, which is a promising process for CO2 to fuels, has been extensively investigated using Ni-based catalysts due to their high CH4 selectivity, high CO2 ...conversion, and affordability. However, owing to its highly exothermic nature, CO2 methanation can cause severe carbon deposition and sintering effects, resulting in catalyst deactivation. This is where high thermal conductivity SiC presents itself as a viable alternative support to enhance the performance of Ni-based catalysts. In this work, Ni catalysts supported on a cheap commercial SiC were prepared by wet impregnation method with different Ni loadings and calcination temperatures. The as-prepared and spent catalysts were characterized using N2 physisorption, X-ray diffraction, H2 temperature-programmed reduction (H2-TPR), temperature-programmed oxidation (TPO) and transmission electron microscopy. H2-TPR analysis revealed that reduction at 400 °C for 15 min is enough to convert most of NiO to active Ni0 to archive the highest activity toward CO2 methanation. The catalytic performance and long-term stability of the as-prepared Ni/SiC catalysts were evaluated for CO2 methanation at stoichiometric CO2/H2 ratio of 1/4, different gas hourly space velocities, reaction temperatures, and reduction conditions. Among the synthesized catalysts, the 10%Ni/SiC-500 exhibited highest CO2 conversion (70%) and CH4 selectivity (98%) as well as stable catalytic performance for 30 h on stream at a GHSV of 20,000 h−1 and reaction temperature of 400 °C.
•Coke-resistant and easily reducible Ni/SiC catalyst was prepared for CO2 methanation.•Ni/SiC reduced at 400 °C for 15 min and 500 °C for 1 h showed similar performance.•Neither oxidation nor significant carbon deposition occurred during the stability test.•Carbon formation was quantitatively determined to be only 0.075 mg/(gcat.•h).
Objectives:
We explored the association of underlying health conditions (UHC) with depression and anxiety, and examined the modification effects of suspected COVID-19 symptoms (S-COVID-19-S), ...health-related behaviors (HB), and preventive behaviors (PB).
Methods:
A cross-sectional study was conducted on 8,291 outpatients aged 18–85 years, in 18 hospitals and health centers across Vietnam from 14th February to May 31, 2020. We collected the data regarding participant's characteristics, UHC, HB, PB, depression, and anxiety.
Results:
People with UHC had higher odds of depression (OR = 2.11;
p
< 0.001) and anxiety (OR = 2.86;
p
< 0.001) than those without UHC. The odds of depression and anxiety were significantly higher for those with UHC and S-COVID-19-S (
p
< 0.001); and were significantly lower for those had UHC and interacted with “unchanged/more” physical activity (
p
< 0.001), or “unchanged/more” drinking (
p
< 0.001 for only anxiety), or “unchanged/healthier” eating (
p
< 0.001), and high PB score (
p
< 0.001), as compared to those without UHC and without S-COVID-19-S, “never/stopped/less” physical activity, drinking, “less healthy” eating, and low PB score, respectively.
Conclusion:
S-COVID-19-S worsen psychological health in patients with UHC. Physical activity, drinking, healthier eating, and high PB score were protective factors.
ABSTRACT Unsustainable exploitation activities (UEAs), combined with the increasing impacts of global climate change are the key causes that lead to soil erosion in the North-Central Vietnam. ...Mountainous areas in the North-Central Vietnam commonly have steep slopes and sandy clay in the surface soil layer, which contribute to enhancing the soil erosion, resulting in a serious loss of life and property. This study investigates the land cover change (LCC) across the Thanh Chuong district by combining Remote Sensing Technique (RST) data with Geographic Information System (GIS) and further, establishing erosion risk hazard maps based on the RUSLE model simulation. To achieve these objectives, Sentinel and Landsat satellite images from the period 2010_2021 were acquired. It was verified that the forest area gradually decreased from 2010_2021, and the average annual soil loss was approximately 25 t per year. The amount of erosion that led to a soil loss of up to 18% of the total land area is related to weather conditions, terrain features, and the soil texture. The decline in the vegetation cover is expected to be the main cause of increasing trends in erosion and soil loss.
RESUMO Atividades de exploração insustentáveis (UEAs), combinadas com os crescentes impactos das mudanças climáticas globais são as principais causas que levam à erosão do solo no centro-norte do Vietnã. As áreas montanhosas no centro-norte do Vietnã geralmente têm encostas íngremes e argila arenosa na camada superficial do solo, o que contribui para aumentar a erosão do solo, resultando em uma séria perda de vidas e propriedades. Este estudo investiga a mudança de cobertura da terra (LCC) em todo o distrito de Thanh Chuong combinando dados da técnica de sensoriamento remoto (RST) com o Sistema de Informação Geográfica (GIS) e, além disso, estabelecendo mapas de risco de erosão com base na simulação do modelo RUSLE. Para atingir estes objetivos, foram adquiridas imagens dos satélites Sentinel e Landsat do período 2010-2021. Verificou-se que a área florestal diminuiu gradualmente de 2010-2021, e a perda média anual de solo foi de aproximadamente 25 t por ano. A quantidade de erosão que levou a uma perda de solo de até 18% da área total da terra está relacionada às condições climáticas, características do terreno e textura do solo. Espera-se que o declínio da cobertura vegetal seja a principal causa das tendências crescentes de erosão e perda de solo.
Background: The COVID-19 pandemic causes a huge burden for affected countries. Several public health interventions were applied to contain the infection. However, the pandemic itself and the lockdown ...measure negatively influence people's lifestyles and psychological health. Purpose: To explore determinants of healthy dietary intake and depression, and examine the interaction between healthy dietary intake and COVID-19 lockdown on depression. Methods: A cross-sectional study was conducted at 18 hospitals and health centers from February 14 to May 31, 2020. Data of 8,291 outpatients were collected including patients' characteristics, clinical parameters, health literacy, healthy dietary intake (using the healthy eating score, HES), other health-related behaviors, and depression (using the patient health questionnaire, PHQ). Depression was defined as PHQ score ≥ 10. Results: Protective factors of healthy dietary intake and depression were higher education, better medication payment ability, higher social status, more physical activity, and higher health literacy, whereas older age, ever married, own business or other types of occupation, lockdown, suspected COVID-19 symptoms, and comorbidity were associated with lower HES scores and a higher depression likelihood. Besides, overweight/obesity and alcohol drinking were associated with lower HES scores. As compared with patients not under lockdown and with lowest HES score, those who were under lockdown and with lowest HES score had 10.6 times higher depression likelihood (odds ratio, OR, 10.60; 95% CI 6.88, 16.32; p < 0.001), whereas people with higher HES score had 15% lower depression likelihood (OR 0.85; 95% CI 0.82, 0.89; p < 0.001). Conclusions: Healthy dietary intake and depression were determined by several sociodemographic, clinical, and behavioral factors. Lockdown measure affects people's dietary intake behavior and depression. Importantly, healthy dietary intake potentially modifies the negative effect of lockdown on depression.
Seasonal and subseasonal variations in the ozone mixing ratio (OMR) are investigated by using continuous 7 year ozonesonde data from Hanoi (21°N, 106°E), Vietnam. The mean seasonal variations for the ...7 years show large amplitude at the upper troposphere and lower stratosphere (UTLS) region (10–18 km) and at the lower troposphere (around 3 km) with standard deviations normalized by the annual mean value of about 30% for both regions. In the UTLS region, the seasonal variation in the OMR shows a minimum in winter and a maximum in spring to summer. The variation seems to be caused by the seasonal change in horizontal transport. Low OMR air masses are transported from the equatorial troposphere in winter by the anticyclonic flow associated with the equatorial convections, and high OMR air masses are transported from the midlatitude stratosphere in summer possibly due to Rossby wave breakings in the UT region and anticyclonic circulation associated with the Tibetan High in the LS region. In the lower troposphere, a spring maximum is found at 3 km height. Biomass burning and tropopause foldings are suggested as possible causes of this maximum. Subseasonal variations in the OMR show large amplitude in the UTLS region (at around 15 km) and in the boundary layer (below 1 km) with the standard deviations normalized by the annual mean larger than 40%. The OMR variations in the winter UTLS region have a negative correlation with the meridional wind. This relation indicates that the low OMRs observed at Hanoi has been transported from the equatorial region.
Key PointsWe have conducted continuous ozonesonde observations at Hanoi since Sep 2004.Seasonal cycle in UTLS ozone with a winter minimum and a summer maximum.A spring maximum is found at 3 km height in the lower troposphere.
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