Search

CC-DMP CCTF@SiO2 core–shell composite microspheres for chiral separation.

PurposeThe purpose of this study is to reveal a sequential mediating process of the impact of shared leadership on team performance by studying the sequential mediating effect of team trust and team learning behavior.Design/methodology/approachThis study develops and examines a sequential mediation model using the meta-analytic structural equation modeling (MASEM) method. The sample adopted consists of 347 independent effect sizes extracted from 280 empirical papers (288 independent studies, N = 21,888 groups).FindingsThe results indicate that team trust and team learning behavior play a sequential mediating effect in the shared leadership–team performance relationship.Practical implicationsThe findings suggest that practitioners should share leadership functions and responsibilities among talented team members. Furthermore, practitioners should strengthen the emotional interaction among team members and give positive feedback to the team's intensive learning behaviors.Originality/valueBy identifying the sequential mediating effect of team trust and team learning behavior, this study not only advances the understandings of a comprehensive mediating process through which shared leadership enhances team performance, but also offers new insights into the interrelationship of different types of mediating mechanisms (i.e. team emergent state and team process) in the shared leadership–team performance relationship.

Background N6-methyladenosine (m6A) methylation is the most abundant chemical posttranscriptional modification of mRNA, and it is associated with the regulation of the immune response to tumors. However, the function of m6A modification in the immune response to endometrial cancer (EC) remains unknown. Our study investigated the immunological role of methyltransferase-like 3 (METTL3) in EC and the underlying molecular mechanism. Methods We investigated the correlation between the expression of METTL3 and CD8 by using an endometrial tissue microarray cohort. Next, we investigated the role and mechanism of METTL3 in the immune response to EC using a mouse tumor model and a CD8+ T cell-EC cell coculture system after METTL3 overexpression or depletion. Additionally, RNA immunoprecipitation (RIP), methylated RIP, and RNA stability experiments were used to investigate the mechanism underlying the function of METTL3 in immunosurveillance of EC. Results METTL3 levels were downregulated in EC patients, low levels of METTL3 were correlated with poor prognosis in EC patients. There was a positive correlation between METTL3 expression and CD8 expression. Overexpression of METTL3 in the EC cell and CD8+ T cell coculture system inhibited EC cell proliferation, migration, and promoted CD8+ T-cell proliferation, and in vivo, METTL3 overexpression increased CD8+ T cell proportions and inhibited EC progression; however, genetic depletion of METTL3 exerted the opposite effects. NLR family CARD domain-containing 5 (NLRC5) was identified as a target of METTL3-mediated m6A modification. The degradation of NLRC5 was increased by YTH domain-containing family 2 (YTHDF2). Conclusions Overall, METTL3, YTHDF2, and NLRC5 have potential to be the diagnostic and prognostic biomarkers for EC. METTL3 facilitated the m6A modifications of NLRC5 and inhibited its degradation through a YTHDF2-dependent mechanism in EC. Genetic overexpression of METTL3 attenuated the immune evasion of EC by promoting NLRC5-mediated immunosurveillance, suggesting that the METTL3/YTHDF2/NLRC5 axis is a promising target of immunotherapy in EC.

Porous organic cages (POCs) are a new subclass of porous materials, which are constructed from discrete cage molecules with permanent cavities via weak intermolecular forces. In this study, a novel chiral stationary phase (CSP) has been prepared by chemically binding a [4 + 6]-type chiral POC (C120H96N12O4) with thiol-functionalized silica gel using a thiol-ene click reaction and applied to HPLC separations. The column packed with this CSP presented good separation capability for chiral compounds and positional isomers. Thirteen racemates have been enantioseparated on this column, including alcohols, diols, ketones, amines, epoxides, and organic acids. Upon comparison with a previously reported chiral POC NC1-R-based column, commercial Chiralpak AD-H, and Chiralcel OD-H columns, this column is complementary to these three columns in terms of its enantiomeric separation; and can also separate some racemic compounds that cannot be separated by the three columns. In addition, eight positional isomers (iodoaniline, bromoaniline, chloroaniline, dibromobenzene, dichlorobenzene, toluidine, nitrobromobenzene, and nitroaniline) have also been separated. The influences of the injection weight and column temperature on separation have been explored. After the column has undergone multiple injections, the relative standard deviations (RSDs) for the retention time and selectivity were below 1.0 and 1.5%, respectively, indicating the good reproducibility and stability of the column for separation. This work demonstrates that POCs are promising materials for HPLC separation.

Porous organic cages (POCs) are an emerging class of porous materials that have aroused considerable research interest because of their unique characteristics, including good solubility and a well-defined intrinsic cavity. However, there have so far been no reports of chiral POCs as chiral stationary phases (CSPs) for enantioseparation by high-performance liquid chromatography (HPLC). Herein, we report the first immobilization of a chiral POC, NC1-R, on thiol-functionalized silica using a mild thiol-ene click reaction to prepare novel CSPs for HPLC. Two CSPs (CSP-1 and CSP-2) with different spacers have been prepared. CSP-1, with a cationic imidazolium spacer, exhibited excellent enantioselectivity for the resolution of various racemates. Twenty-three and 12 racemic compounds or chiral drugs were well enantioseparated on the CSP-1-packed column under normal-phase and reversed-phase conditions, respectively, including alcohols, diols, esters, ethers, ketones, epoxides, organic acids, and amines. In contrast, chiral resolution using CSP-2 (without a cationic imidazolium spacer)-packed column B was inferior to that of column A, demonstrating the important role of the cationic imidazolium spacer for chiral separation. The chiral separation capability of column A was also compared with that of two most popular commercial chiral columns, Chiralpak AD-H and Chiralcel OD-H, which exhibits good chiral recognition complementarity with the two commercial chiral columns. In addition, five positional isomers dinitrobenzene, nitroaniline, chloroaniline, bromoaniline, and iodoaniline were also well separated on column A. The effects of temperature, mobile phase composition, and injected analyte mass for separation on column A were investigated. Column A also showed good stability and reproducibility after repeated injections. This work demonstrates that chiral POCs are promising chiral materials for HPLC enantioseparation.

ContextPrimary ovarian insufficiency (POI) is a heterogeneous disease with an unknown underlying trigger or root cause. Recently many studies evaluated noncoding RNAs (ncRNAs), especially microRNAs (miRNAs), long noncoding RNA (lncRNAs), circular RNAs (circRNAs), and small interfering RNAs (siRNAs) for their associations with POI.Evidence acquisitionIn this review, we outline the biogenesis of various ncRNAs relevant to POI and summarize the evidence for their roles in the regulation of disease occurrence and progression. Articles from 2003 to 2022 were selected for relevance, validity, and quality from results obtained in PubMed and Google Scholar using the following search terms: noncoding RNAs; primary ovarian insufficiency; premature ovarian failure; noncoding RNAs and primary ovarian insufficiency/premature ovarian failure; miRNAs and primary ovarian insufficiency/premature ovarian failure; lncRNAs and primary ovarian insufficiency/premature ovarian failure; siRNAs and primary ovarian insufficiency/premature ovarian failure; circRNAs and primary ovarian insufficiency/premature ovarian failure; pathophysiology; and potential treatment. All articles were independently screened for eligibility by the authors.Evidence synthesisThis review summarizes the biological functions and synthesis of miRNAs, lncRNAs, siRNAs, and circRNAs in POI and discusses the findings of clinical and in vitro and in vivo studies. Although there is variability in the findings of individual studies, overall the available literature justifies the conclusion that dysregulated ncRNAs play significant roles in POI.ConclusionThe potential of ncRNAs in the treatment of POI requires further investigation, as ncRNAs derived from mesenchymal stem cell–secreted exosomes play pivotal roles and have considerable therapeutic potential in a multitude of diseases.

Separations and analyses of chiral compounds are important in many fields, including pharmaceutical production, preparation of chemical intermediates, and biochemistry. High-performance liquid chromatography using a chiral stationary phase is regarded as one of the most valuable methods for enantiomeric separation and analysis because it is highly efficient, is broadly applicable, and has powerful separation capability. The focus for development of this method is the identification of novel chiral stationary phases with superior recognition performance and good stability. The present article reviews recent progress in the development of new chiral stationary phases for high-performance liquid chromatography between January 2018 and June 2021. These newly reported chiral stationary phases are divided into three categories: small organic molecule-based (cyclodextrin and its derivatives, macrocyclic antibiotics, cinchona alkaloids, and other low molecular weight chiral molecules), macromolecule-based (cellulose and amylose derivatives, chitin and chitosan derivatives, and synthetic helical polymers) and chiral porous material-based (chiral metal-organic frameworks, chiral covalent organic frameworks, and chiral inorganic mesoporous silicas). Each type of chiral stationary phase is discussed in detail.

There is currently no effective analytical method in colorectal image analysis, which leads to certain errors in colorectal image analysis. In order to improve the accuracy of colorectal imaging detection, this study used a genetic algorithm as the data mining algorithm and combined it with image processing technology to perform image analysis. At the same time, combined with the actual requirements of image detection, the gray theory model is used as the basic theory of image processing, and the image detection prediction model is constructed to predict the data. In addition, in order to study the effectiveness of the algorithm, the experiment is carried out to analyze the validity of the data of the study, and the predicted value is compared with the actual value. The research shows that the proposed algorithm has certain accuracy and can provide theoretical reference for subsequent related research.

The unique features of uniform and adjustable cavities, abundant chiral active sites, and high enantioselectivity make chiral metal-organic frameworks popular as an emerging candidate for enantioselective separation. However, the wide particle size distribution and irregular shape of as-synthesized metal-organic frameworks result in low column efficiency, undesired chromatographic peak shape, and high column backpressure of such metal-organic frameworks packed columns. Herein, we report the fabrication of chiral core-shell microspheres [Cu2 (d-Cam)2 (4,4'-bpy)]n @SiO2 composite for high-performance liquid chromatography enantioseparation to overcome the above-mentioned problems. The [Cu2 (d-Cam)2 (4,4'-bpy)]n @SiO2 packed column gave high-resolution separation of racemates under low column backpressure (10-22 bar), indicating its synergistic effect of the good column packing property of the SiO2 microspheres and the chiral recognition ability of [Cu2 (d-Cam)2 (4,4'-bpy)]n crystals. Thirteen kinds of chiral compounds including alcohols, amines, ketones, epoxides, and organic bases were well separated with good peak shapes and high column efficiency (18200 plates/m for 1-(9-anthryl)-2,2,2-trifluoroethanol) on the [Cu2 (d-Cam)2 (4,4'-bpy)]n @SiO2 packed column. Among them, seven pairs of enantiomers achieved baseline separation and the resolution value for 1-(9-anthryl)-2,2,2-trifluoroethanol reached 11.22. Some effects such as column temperature, and analytes mass on the enantioseparations have been investigated. In addition, the [Cu2 (d-Cam)2 (4,4'-bpy)]n @SiO2 packed column exhibited good stability and repeatability for the separation of chiral compounds. The relative standard deviations for five replicate separations of 1-phenylethanol were less than 1.0, 1.5, 3.0, and 2.0% for the retention time, peak area, number of theoretical plates, and resolution, respectively. The research results demonstrated the development of chiral metal-organic frameworks core-shell microspheres composite provide a promising platform for their practical application in chiral separation fields.

To investigate the effect of open wedge tibial high osteotomy on patella position, anterior knee pain and joint function.From June 2016 to June 2021, 109 patients (111 knees) with medial knee osteoarthropathy treated by open wedge tibial high osteotomy were included according to the inclusion and exclusion criteria, including 41 males and 68 females;the age ranged from 38 to 78 years old with an average of(57.98±7.07) years;the course of disease ranged from 1 to 36 months with an average of (8.58±6.91) months. The femoral tibial angle(FTA), medial proximal tibial angle(MPTA), weight bearing line(WBL) percentage, Caton Deschamps index (CD index), lateral patella tilt angle (LPTA) and lateral patella shift (LPS) were observed and compared before and after operation. Lysholm score was used to evaluate the knee function, visual analogue scale(VAS) was used to evaluate the degree of anterior knee pain, and Kellgren Lawrence(K-L) grading system was used to evaluate the progress of patellofemoral osteoarthritis.All patients were followed up for 6 to 38 months with an average of (12.41±2.40) months. The preoperative FTA, MPTA, WBL percentage, CD index, and LPTA were significantly different from those at the last follow-up(After open wedge tibial high osteotomy, the position of patella is lowered and the patella is tilted outward, but the knee function and anterior knee pain are significantly improved. Adverse changes in patella position caused by open wedge tibial high osteotomy may not affect clinical outcomes.

As a new type of multifunctional material, metal−organic frameworks (MOFs) have a wide application prospect in the field of chiral separation. In this study, a homochiral MOF [Ni(S-mal)(bpy)]n was synthesized by the reaction of S-malic acid (S-mal) and 4,4′-bipyridine (bpy) with nickel acetate. The homochiral MOF [Ni(S-mal)(bpy)]n was explored as a new chiral stationary phase for HPLC separation of racemic compounds using n-hexane−isopropanol as a mobile phase. A series of racemic compounds were separated on this column. The results showed that the homochiral MOF column exhibited good chiral recognition ability toward six racemic compounds including amlodipine, ibuprofen, flurbiprofen, propranolol hydrochloride, chlorphenamine maleate and 1-p-chlorobenzyl−ethanol. The homochiral MOF column also offered good reproducibility and stability for the enantioseparation.

Chiral metal-organic frameworks have shown great potential in enantioselective separation and asymmetric catalysis due to their diverse and adjustable structures with abundant chiral recognition sites. Herein, a new chiral post-synthetic modification was used for preparing an achiral@chiral metal-organic frameworks core-shell composite [Cu

In order to reveal the changing law of the mechanical response of asphalt pavements under the action of vehicle load and provide references for the design of durable pavements, three typical asphalt pavement structures with flexible base (S1), combined base (S2), and semi-rigid base (S3) were selected to perform field strain tests under static and dynamic load using the fiber Bragg grating optical sensing technology. The changing characteristics of the strain field along the horizontal and depth directions of pavements were analyzed. The results indicate that the most unfavorable asphalt pavement layers were the upper-middle surface layer and the lower base layer. In addition, the most unfavorable loading positions on the surface layer and the base layer were the center of wheel load and the gap center between two wheels, respectively. The most unfavorable layer of the surface layers gradually moved from the lower layer to the upper layer with the increase of base layer modulus. The power function relationships between structural layer strain and vehicle speed were revealed. The semi-rigid base asphalt pavement was the most durable pavement type, since its strain value was lower compared to those of the other structures.

A homochiral metal–organic framework (MOF) comprising [Co(L)(bpe)2(H2O)2]·H2O was prepared using (1R,2R)-(−)-1,2-cyclohexanedicarboxylic acid (H2L) and 1,2-bis(4-pyridyl)-ethylene as organic ligands. The homochiral MOF [Co(L)(bpe)2(H2O)2]·H2O was explored as chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) separation of racemates. Nine racemates including naphthol, alcohol, diol, amine, ketone, ether and organic acid were well separated on the homochiral MOF [Co(L)(bpe)2(H2O)2]·H2O column (250 mm long × 4.6 mm i.d.). The relative standard deviation for five replicate separations of 1,1′-bi-2-naphthol is 0.69% for the retention time, indicating that the good reproducibility and stability of the homochiral MOF column for HPLC enantioseparation. The results indicated that the homochiral MOF as CSP is practical, which promotes the application of homochiral MOFs in HPLC.

Metal-organic cages (MOCs), as a promising class of crystalline porous materials with well-defined cavities, have attracted wide attention due to their multifarious potential applications in gas storage, host-guest chemistry, molecular recognition, separation, catalysis, sensing, and drug delivery and so on. Herein, we report that a chiral MOC [Fe

A spherical chiral porous organic polymer (POPs) COP-1 is synthesized by the Friedel-Crafts alkylation reaction of Boc-3-(4-biphenyl)-L-alanine (BBLA) and 4,4'-bis(chloromethyl)-1,1'-biphenyl (BCMBP), which was used as a novel chiral stationary phase (CSPs) for mixed-mode high-performance liquid chromatography (HPLC) enantioseparation. The racemic compounds were resolved in normal-phase liquid chromatography (NPLC) using n-hexane/isopropanol as mobile phase and reversed-phase liquid chromatography (RPLC) using methanol/water as mobile phase. The COP-1-packed column exhibited excellent separation performance toward various racemic compounds including alcohols, amines, ketones, esters, epoxy compounds, organic acids, and amino acids in NPLC and RPLC modes. The effects of analyte mass and column temperature on the separation efficiency of racemic compounds were investigated. In addition, the chiral resolution ability of the COP-1-packed column not only can be complementary in RPLC/NPLC modes but also exhibit a good chiral recognition complementarity with Chiralpak AD-H column and chiral porous organic cage (POC) NC1-R column. The relative standard deviations (RSD) (n = 5) of the retention time, resolution value, and peak area by repeated separation of 1-(4-chiorophenyl)ethanol are all below 3.0%. The COP-1 column shows high column efficiency (e.g., 17,320 plates m

Porous organic cages (POCs) are an emerging class of porous molecular materials which self-assembled by discrete, shape-persistent, cage-like molecules and have recently received intensive interest in diverse fields. In this work, a hydroxyl-functionalized homochiral POC was synthesized by [4 + 6] condensation of 2-hydroxy-1,3,5-triformylbenzene with (1R, 2R)-diaminocyclohexane and coated on a capillary column for gas chromatography (GC) separations. Forty-one pairs of enantiomers belonging to various classes have been resolved on the column, including alcohols, diols, esters, lactones, halohydrocarbons, ethers, epoxides, ketones and sulfoxides. Compared with β-cyclodextrin derivative-based commercial β-DEX 120 column, previously reported chiral POCs- (CC9 and CC10) based columns, there are 12, 27 and 19 pairs of studied enantiomers cannot be resolved on β-DEX 120 column, CC9 column and CC10 column, respectively. Besides, both separation factors and resolution values of some racemates are higher on this column than those on β-DEX 120 column, CC9 column and CC10 column. The results demonstrate that the column exhibits good chiral recognition complementarity or superior chiral resolution capability to those columns which used for comparison, and the introduction of hydroxyl group enhances hydrogen-bonding interaction to some racemates, leading to better enantioselectivity. The column also shows excellent separation performance toward positional isomers of dichlorobenzene, dibromobenzene, nitrotoluene, chlorotoluene, nitrobromobenzene and nitrochlorobenzene. The retention time and selectivity of analytes have no significant changes after more than 500 injections and 260 °C conditioned for 6 h, showing the good repeatability and thermal stability of the column. This work indicates the promising prospect of POCs for GC separation, especially for the separation of enantiomers and also demonstrates the significance of design and synthesis of more functionalized chiral POCs for GC enantioseparation that broaden the enantiomer separation scope and applicability of POCs-based columns through their chiral recognition complementarities.

Chiral metal-organic frameworks (MOFs) have aroused great attention in the chiral separation field based on their excellent characteristics, including abundant topological structures, large surface area, adjustable pore/channel sizes, multiple active sites, and good chemical stability. However, the irregular morphology and nonuniformity of the synthesized MOF particles cause low column efficiency and high column backpressure for MOF-packed columns, which significantly affects their separation performance. Herein, we prepared a homochiral d-his-ZIF-8@SiO2 composite by growing of d-his-ZIF-8 on the carboxylic-functionalized SiO2 microspheres via a simple one-pot synthesis approach. The d-his-ZIF-8@SiO2 core-shell microspheres with uniform particles and narrow size distribution were applied as the chiral stationary phase (CSP) for enantioseparations in HPLC. Various racemates were separated on the d-his-ZIF-8@SiO2-packed columns with n-hexane/isopropanol as the mobile phase. Eighteen racemates including alcohol, phenol, amine, ketone, and organic acid were well resolved on the homochiral d-his-ZIF-8@SiO2 CSP. The d-his-ZIF-8@SiO2 core-shell microspheres' CSP possesses an excellent chiral resolution ability toward various racemic compounds with good reproducibility and stability. Hence, the fabrication of chiral MOF@SiO2 core-shell microspheres is an effective strategy to improve the application of homochiral MOFs as CSPs in the field of chromatography.

Background China has experienced a continuous decreasing trend in the incidence of hepatitis A in recent years. Temporal trend analyses are helpful in exploring the reasons for the changing trend. Thus, this study aims to analyse the incidence trend of viral hepatitis A by region and age group in mainland China from 2004 to 2017 to evaluate the effectiveness of prevention and control measures. Methods Data on hepatitis A and population information were collected and analysed with a joinpoint regression model. Annual percentage changes (APCs) and average annual percentage changes (AAPCs) were estimated for the whole country and for each region and age group. Results From 2004 to 2017, the seasonality and periodicity of hepatitis A case numbers were obvious before 2008 but gradually diminished from 2008 to 2011 and disappeared from 2012–2017. The national incidence of hepatitis A (AAPC = − 12.1%) and the incidence rates for regions and age groups showed decreasing trends, with differences in the joinpoints and segments. Regarding regions, the hepatitis A incidence in the western region was always the highest among all regions, while a nonsignificant rebound was observed in the northeastern region from 2011 to 2017 (APC = 14.2%). Regarding age groups, the hepatitis A incidence showed the fastest decrease among children (AAPC = − 15.3%) and the slowest decrease among elderly individuals (AAPC = − 6.6%). Among all segments, the hepatitis A incidence among children had the largest APC value in 2007–2017, at − 20.4%. Conclusion The national annual incidence of hepatitis A continually declined from 2004 to 2017 and the gaps in hepatitis A incidence rates across different regions and age groups were greatly narrowed. Comprehensive hepatitis A prevention and control strategies, including the use of routine vaccination during childhood in mainland China, especially the implementation of the national Expanded Program on Immunization (EPI) in 2008, resulted in substantial progress from 2004 to 2017. However, gaps remain. Regular monitoring and analysis of hepatitis A epidemic data and prompt adjustment of hepatitis A prevention and control strategies focusing on children, elderly individuals and those living in certain regions are recommended.

The fascinating framework structures and unique properties of chiral covalent organic frameworks (COFs) make them promising candidates as novel separation medium for high-performance liquid chromatography (HPLC). However, the irregular morphology, inhomogeneous particle size, and low density of conventional COF particles will lead to a low column efficiency, undesirable chromatographic peak shape, and high column backpressure of such COF-packed columns. In this work, a chiral COF CTpBD was synthesized by the Schiff base reaction between benzidine (BD) and chiral organic monomer CTp obtained through the reaction of 1,3,5-triformylphoroglucinol (Tp) and (+)-diacetyl-L-tartaric anhydride ((+)-Ac-L-Ta). The chiral COF CTpBD was immobilized on the surface of amino functionalized silica (SiO2-NH2) by an in situ growth approach to prepare the chiral COF core-shell microsphere composite CTpBD@SiO2, which was used as a novel chiral stationary phase (CSP) for HPLC enantioseparation. Various kinds of racemates were separated on the CTpBD@SiO2-packed column with a low column backpressure (8–11 bar). Some effects such as the analyte mass and column temperature on the HPLC enantioseparation have been studied in detail. The fabricated CTpBD@SiO2-packed column exhibited high column efficiency (e.g., 16,800 plates m−1 for atenolol), high enantioselectivity, and good reproducibility toward various racemates. The highest resolution value, retention factor, and separation factor reach to 2.11, 2.85, and 3.73, respectively. The relative standard deviations (RSD) of peak area, peak height, half-peak width, and retention time of atenolol were all below 3.0%.

Since some metal-organic cages (MOCs) have been synthesized in past several years, the applications of MOCs such as drug delivery, molecular recognition, separation, catalysis, and gas storage, etc. have been witnessed with a significant increase. However, to the best of our knowledge, so far no one has used MOCs as chiral stationary phase to separate chiral compounds in CEC. In this study, three MOCs were developed as the stationary phase for CEC separation of enantiomers. The MOCs coated capillary column showed good chiral recognition ability for some chiral compounds, including amine, alcohols, ketone, etc. The influence of buffer concentration, applied voltage, pH of buffer solution on the chiral separations was also investigated. The RSDs of run-to-run, day-to-day, and column-to-column for retention time were 2.1-4.67%, 1.2-4.36%, and 3.62-6.43%, respectively. This work reveals that the chiral MOCs material is feasible for the enantioseparation in CEC.