Numerical Stability and Accuracy of Contact Angle Schemes in Pseudopotential Lattice Boltzmann Model for Simulating Static Wetting and Dynamic Wetting

There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity scheme(IVD scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the fluid layer density above the wall(MPB-C scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the weighted average density of surrounding fluid nodes(MPB-W scheme)and the geometric formulation scheme(GF scheme).But the numerical stability and accuracy of the schemes for wetting simulation remain unclear in the past.In this paper,the numerical stability and accuracy of these schemes are clarified for the first time,by applying the five widely used contact angle schemes to simulate a two-dimensional(2D)sessile droplet on wall and capillary imbibition in a 2D channel as the examples of static wetting and dynamic wetting simulations respectively.(i)It is shown that the simulated contact angles by the GF scheme are consistent at different density ratios for the same prescribed contact angle,but the simulated contact angles by the PB scheme,IVD scheme,MPB-C scheme and MPB-W scheme change with density ratios for the same fluid-solid interaction strength.The PB scheme is found to be the most unstable scheme for simulating static wetting at increased density ratios.(ii)Although the spurious velocity increases with the increased liquid/vapor density ratio for all the contact angle schemes,the magnitude of the spurious velocity in the PB scheme,IVD scheme and GF scheme are smaller than that in the MPB-C scheme and MPB-W scheme.(iii)The fluid density variation near the wall in the PB scheme is the most significant,and the variation can be diminished in the IVD scheme,MPB-C scheme andMPBWscheme.The variation totally disappeared in the GF scheme.(iv)For the simulation of capillary imbibition,the MPB-C scheme,MPB-Wscheme and GF scheme simulate the dynamics of the liquid-vapor interface well,with the GF scheme being the most accurate.The accuracy of the IVD scheme is low at a small contact angle(44 degrees)but gets high at a large contact angle(60 degrees).However,the PB scheme is the most inaccurate in simulating the dynamics of the liquid-vapor interface.As a whole,it is most suggested to apply the GF scheme to simulate static wetting or dynamic wetting,while it is the least suggested to use the PB scheme to simulate static wetting or dynamic wetting.

An Isolable Phosphinogermylyne as a Synthon of One-Coordinate GeⅠRadical

Reduction of chlorogermylene MsFluindtBu-GeCl 1 with potassium graphite(KC8)afforded putative germylyne radical MsFluindtBu-Ge 2 as confirmed by electron paramagnetic resonance(EPR)spectroscopy.However,it slowly decayed via C—H bond activation at the fluorenyl moiety to yield a bis(germylene)3 at room temperature.By using a Lewis base to stabilize the unoccupied p orbital at the GeⅠradical center,acyclic two-coordinate GeⅠradicals MsFluindtBu-Ge(IMe4)4(IMe4=1,3,4,5-tetramethyl-imidazolin-2-ylidene),MsFluindtBu-Ge(IiPr)5(IiPr=1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene),MsFluindtBu-Ge(PMe3)6 were isolated in crystalline forms.The unpaired electron in 4-6 mainly resides at the Ge 4p orbital as revealed by EPR spectroscopic studies and theoretical calculations.Interestingly,facile ligand exchange of PMe3 in 6 with IMe4 and IiPr was observed to afford 4 and 5,respectively.Moreover,phosphinogermylyne 6 reacted with PhEEPh(E=S,Se),4-tetrabutylphenylacetylene(Ar'CCH),[CpMo(CO)3]2 and nBu3SnH to furnish germylenes MsFluindtBu-GeEPh(E=S 7,Se 8),MsFluindtBu-GeCH=CHAr'9,a germylyne complex MsFluindtBu-Ge≡Mo(CO)2Cp 10 and a Ge(Ⅳ)compound MsFluindtBu-GeH2SnnBu311,respectively.The reactivity studies demonstrate that 6 can act as a synthon of one-coordinate germylyne radical attributing to labile coordination of trimethylphosphine.

Roles of hydroxyl and oxygen vacancy of CeO_(2)·xH_(2)O in Pd-catalyzed ethanol electro-oxidation

In the field of noble metal-catalyzed alcohol electro-oxidation reaction(AOR),huge attention is paid on the composition,size,facet,and structure of the metals,while the support engineering should also be emphasized.CeO_(2)has been widely used as a unique support in AOR,primarily due to its abundant oxygen vacancies(O_(v)).Herein,we report CeO_(2)·xH_(2)O nanoparticles with both massive hydroxyl groups(OH)and O_(v)remarkably enhance the catalytic activity and stability of Pd toward ethanol oxidation reaction(EOR).The CO striping experiments and density functional theory(DFT)calculations suggest that OH and O_(v)on CeO_(2)·xH_(2)O surface bring about a large downshift of Pd d-band center and a significant weakening of CO absorption on Pd.Moreover,OH and O_(v)also play synergic roles in the removal of toxic intermediates.Consequently,the important roles of OH and O_(v)of CeO_(2)·xH_(2)O are confirmed in Pd-catalyzed EOR.The facile CeO_(2)·xH_(2)O-enhanced strategy can contribute to the catalyst design for other energy conversion reactions.

Functional outcomes of Tai Chi exercise prescription in women with knee osteoarthritis

Knee Osteoarthritis(KOA)is the most common type of knee joint injury and also a risk factor for multiple health consequences and is prevalent among older women.The updated clinical guidelines for KOA treatment by the American Rheumatism Association recommend Tai Chi exercise.However,a literature review outlined limitations in Tai Chi intervention implementations.This study aimed to address some of the gaps.This study selected thirty female patients to participate in Tai Chi exercises and undergo relevant tests.The subjects were randomly assigned to Tai Chi or education groups.Independent sample t-tests were conducted to compare the difference in health indicators between the two groups after the intervention.The difference-in-differences(DID)regression was performed to assess the difference in the health outcomes between the two groups at baseline and follow-up and the difference in the differences.After the completion of the intervention,the Tai Chi group reported significantly improved KOA symptoms,physical fitness,and health status indicators than the control group.Specifically,the group differences were significantly larger at the baseline than at the follow-up.Our findings provide compelling evidence of the effects of the innovative Tai Chi exercise prescription specifically designed for KOA patients.The empirical evidence on its effectiveness in alleviating KOA symptoms and improving the overall health of middle-aged and elderly women with KOA suggested that Tai Chi intervention exercise has huge prospects for integration in KOA rehabilitation therapy.

Association Between Physical Activity and Physical Fitness Among Adults Aged 40 to 79 Years—Beijing,China,2020–2021

Summary What is already known about this topic?Physical fitness is well documented to be associated with physical activity among adults in the United States.In China,research on this association places a heavier emphasis on the populations of children and adolescents.What is added by this report?Physical fitness was shown to be positively associated with physical activity among adults aged 40 to 79 years in China.In populations with lower levels of physical fitness,this association was stronger.The coefficients of the log-transformed metabolic equivalent value of physical activity(logPA)in quantile regression models at the 25th,50th,75th,and 90th percentile of the physical fitness indicators were 1.14,1.04,0.89,and 0.84,respectively.

The Distribution and Potential Exposure Factors of Physical Activity Level Among Middle-Aged and Elderly Population—Six Communities,Beijing,China,October 2020 to January 2021

Summary What is already known about this topic?Available evidence suggested that 31%of the world’s population do not meet the minimum recommendations for physical activity.What is added by this report?The latest findings showed that physical activity level(PAL),metabolic equivalents(MET)in min/week with<4,500(low),4,500–6,000(moderate)and≥6,000(high)accounted for 45.72%,25.62%,and 28.66%of middle-aged and elderly population in Changchunyuan Community,Weixiuyuan Community,Zhongguanyuan Community,Yanbeiyuan Community,Kangzeyuan Community,and Xima Community,respectively.The moderate and high PAL was associated with a decreased risk of hypertension,cardiovascular disease,dyslipidemia,and poor sleep.What are the implications for public health practice?More attention should be given to the middle-aged population who may be at high risk of insufficient physical activity in urban environments as it is of public health significance for improving the community population health.

Fall Injuries and Depressive Symptoms Among Older Adults and the Mediating Effects of Social Participation—China,2011–2018

Summary What is already known on this topic?Prior studies found that fall events were associated with a higher level of depressive symptoms and a lower level of social functioning and social participation.In addition,social participation has also been significantly associated with better conditions of depressive symptoms.What is added by this report?