Influence of geological factors on coal permeability in the Sihe coal mine

Permeability of coal reservoirs influence the extraction of coal gas from coal seams.Twelve coal samples were collected at an anticline and a syncline of the No.3 coal seam in the Sihe coal mine.Porosity,permeability,pore size,vitrinite reflectance,and liquid nitrogen adsorption of the samples were evaluated.Structural curvatures at the sample locations,and the distance between the sampling locations and the nearest faults were calculated based on seismic data.The influences of the evaluated parameters on permeability were analyzed.Major factors that influence permeability of the No.3 coal seam were extracted using principal component analysis(PCA).Based on the porosity–permeability model derived from the Archie formula and classic Kozeny–Carman equation,we deduced that the permeability of coal increased with an increase in porosity.With an increase in average vitrinite reflectance,permeability decreases first and then increases.PCA results showed that coal permeability was regulated by three key components representing three modes.The first component included pore size,depth,and pore complexity accounting for 52.59%of the variability indicating that it was the most important in controlling permeability.The second component included specific surface area,structural curvature,and porosity,and the third component comprised of specific surface area,porosity,and average vitrinite reflectance.Overall,pore diameter and complexity had significant effects on coal permeability.The results show that researchers and stakeholders must consider the interactions among multiple factors rather than single factors to understand the influences on permeability to facilitate efficient utilization of coalbed methane resources.

N,O-Bidentated difluoroboron complexes based on pyridine-ester enolates:Facile synthesis,post-complexation modification,optical properties,and applications

An array of pyridine-ester enolate based organoboron complexes has been designed and synthesized via a one-pot cascade of Pd-catalyzedα-arylation and BF2complexation.The rapid structure-activity relationship(SAR)studies indicated that unsymmetrical N,O-chelated BF2complexes were highly fluorescent in solid state,and exhibited large Stokes shifts,excellent photostability,along with insensitivity to p H.Theα-aryl group could not only modulate the electronic effect but also inhibit the intermolecularπ-πstacking to promote the aggregation-induced emission(AIE)effect.DFT calculations and experiments identified that the intramolecular charge transfer properties of these N,O-chelates could be switched by the modification of substituents,resulting tunable fluorescence wavelengths.Furthermore,post-complexation modification was accomplished,including Suzuki-Miyaura cross-coupling,Buchwald-Hartwig amination,oxidative cleavage,along with a unique triple substitution reaction involving propargyl Grignard reagents.The exemplificative application of dimethylamine substituted boron complex as a reversible acidic vapor sensor was also demonstrated.

Direct benzylic functionalization of pyridines:Palladium-catalyzed mono-α-arylation of α-(2-pyridinyl)acetates with heteroaryl halides

Herein,we report a Pd-catalyzed mono-a-arylation reaction for pyridine benzylic functionalization.This approach serves as an efficient alternative to synthesize di-heteroaryl acetates in good yields and selectivities.Moreover,the method is applicable to heteroa ryl substrate combinations,and exhibits great functional group tolerance.A streamlined protocol also enables the rapid synthesis of diheteroaryl ketones.The synthetic value was also demonstrated by scale-up experiments.

Clinical significance of serum IgM and IgG levels in COVID-19 patients in Hubei Province,China

Background:There have been many studies about coronavirus disease 2019(COVID-19),but the clinical signifi-cance of quantitative serum severe acute respiratory syndrome-coronavirus-2(SARS-CoV-2)-specific IgM and IgG levels of COVID-19 patients have not been exhaustively analyzed.We aimed to investigate the time profiles of these IgM/IgG levels in COVID-19 patients and their correlations with clinical features.Methods:A multicenter clinical study was conducted from February 20 to March 52020.It involved 179 COVID-19 patients(108 males and 71 females)from five hospitals in Huangshi in Hubei Province,China.To detect SARS-CoV-2-specific IgM/IgG,quantitative antibody assays(two-step indirect immunoassays with direct chemilu-minescence technology)based on the nucleocapsid protein(NP)and spike protein 1(S1)were used.For normally distributed data,means were compared using the t-test,𝜒2-test,or exact probability method.For categorical data,medians were compared using Mann-Whitney U test.Results:The median age was 57(44-69)years(58[38-69]for males and 57[49-68]for females).The median duration of positive nucleic acid test was 22.32(17.34-27.43)days.The mortality rate was relatively low(3/179,1.68%).Serum SARS-CoV-2-specific IgG was detected around week 1 after illness onset,gradually increased until peaking in weeks 4 and 5,and then declined.Serum IgM peaked in weeks 2 and 3,then gradually declined and returned to its normal range by week 7 in all patients.Notably,children had milder respiratory symptoms with lower SARS-CoV-2-specific IgM/IgG levels.The duration of positive nucleic acid test in the chronic obstructive pulmonary disease(COPD)group was 30.36(18.99-34.76)days,which was significantly longer than that in the non-COPD group(21.52[16.75-26.51]days;P=0.025).The peak serum SARS-CoV-2-specific IgG was sig-nificantly positively correlated with the duration of positive nucleic acid test.The incidence rate of severe and critical cases in the IgM hi group(using the median IgM level of 29.95 AU/mL as the cutofffor grouping)was about 38.0%(19/50),which was twice as much as that in the IgM lo group(18.4%;9/49).The patients with positive chest imaging and lymphocytopenia(<1×10^(9)/L)had a higher SARS-CoV-2-specific IgM level.Conclusions: Quantitative SARS-CoV-2-specific IgM and IgG levels are helpful for the diagnosis, severity classifi- cation, and management of COVID-19 patients, and they should be monitored in each stage of this disease.