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In this work, experiments and comprehensive insights into the proposed covering liquid method to intensify self-preservation effect for methane (CH4) storage are presented. The CH4 hydrate decomposition percentage was 17.6% with the pressure of 0.61 MPa after 12 h at 266.0 K without a covering liquid, which can be reduced to 12.4%, 13.8%, 13.0%, and 8.3% with the pressure of 0.26 MPa, 0.33 MPa, 0.51 MPa, and 0.37 MPa by covering with tetrahydrofuran (THF), cyclopentane (CP), cyclohexane, and n-tetradecane, respectively. When the temperature for CH4 hydrate decomposition was 274.2 K, covering with THF, CP, cyclohexane, and n-tetradecane failed to inhibit CH4 hydrate decomposition. The results suggested that the covering liquid may form a new solid layer (a hydrate layer or other solidified layer) around the CH4 hydrate, which inhibit CH4 transfer below the freezing point of water. However, the new solid layer cannot resist the fast transfer of CH4 from decomposed CH4 hydrate above the freezing point of water. The same phenomenon was also observed in a sodium dodecyl sulfonate (SDS)-dry solution CH4 hydrate formation system. Therefore, the covering method can only intensify the self-preservation effect below the freezing point of water, but cannot generate a self-preservation effect.

Two bipolar molecules CzT2.1 and CzT2.2 are examined as electron acceptors to form exciplexes with electron donors 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 4,4’,4’’-tris(carbazol-9-yl)-triphenylamine (TCTA), respectively. The bipolar structural feature endows 1-(4-(9H-carbazol-9-yl)phenyl)-9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9H-carbazole (CzT2.1) and 1-(4-(9H-carbazol-9-yl)phenyl)-9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9H-carbazole (CzT2.2) with hole- and electron-transporting properties, as well as the possibility of forming charge transfer emissive states. An aggregation-induced emission (AIE) protocol was employed to quickly screen the feasibility of exciplex formation of four donor (D):acceptor (A) blends as nanoparticles dispersed in tetrahydrofuran (THF) solution containing a high portion of water. Then, the vacuum-deposited D:A blended films were analyzed with steady and dynamic photophysical characterizations. The observed results indicate that the emissions of the D:A blends are contributed from the bipolar acceptor as well as the exciplex system. The proportion for each contribution relies on the exciplex formation efficiency and the intrinsic relaxation behavior of the bipolar acceptor. The D:A blends employing a stronger donor (TAPC) give a higher propensity of forming exciplexes as compared to those of counterparts with a weaker donor TCTA. The green device (EL λmax = 537 nm) with TAPC:CzT2.1 exciplex-forming blend as the emitting layer exhibits a high maximum external quantum efficiency (EQE) of 12.5% (39.2 cd A−1, 41.4 lm W−1) and limited efficiency roll-off (12.5%, 34.8 cd A−1, 39.1 lm W−1 at 100 cd m−2) owing to the fast decay lifetimes of the exciplex. The green exciplex-based device (EL λmax = 514 nm) adopting TAPC:CzT2.2 blend as the emitting layer offers an even higher EQE of 15.0% (45.7 cd A−1, 50.0 lm W−1), yet suffers a limited efficiency roll-off (14.3%, 43.6 cd A−1, 45.0 lm W−1 at 100 cd m−2) due to the prolonged decay lifetimes of the emissive components. This works highlights the use of emissive bipolar acceptors to create exciplex emission channels working together with the inherent acceptor emission for enhancing the organic light-emitting diode (OLED) device performance.

Introduction: The amentoflavone (AMF) loaded polymeric sub-micron particles were prepared using supercritical antisolvent (SAS) technology with the aim of improving the anticancer activity of AMF. Methods: Zein and phospholipid mixtures composed of Hydrogenated Phosphatidylcholine (HPC) and egg lecithin (EPC) were used as carrier materials and, the effects of carrier composition on the product morphology and drug release behavior were investigated. When the mass ratio of Zein/HPC/ EPC was 7/2/1, the AMF loaded particles were spherical shape and sub-micron sized around 400 nm, with a drug load of 4.3±0.3 w% and entrapment efficacy of 87.8±1.8%. The in vitro drug release assay showed that adding EPC in the wall materials could improve the dispersion stability of the released AMF in an aqueous medium, and the introduction of HPC could accelerate the drug release speed. Results: MTT assay demonstrated that AMF-loaded micron particles have an improved inhibitory effect on A375 cells, whose IC50 was 37.39μg/ml, compared with that of free AMF(130.2μg/ml). Conclusion: It proved that the AMF loaded sub-micron particles prepared by SAS were a prospective strategy to improve the antitumor activity of AMF, and possibly promote the clinical use of AMF preparations.

Compared with the traditional suspension fermentation, immobilised biofilm fermentation has advantages of strong resistance, high yield and continuous fermentation and is conducive to improving the industrial fermentation methods. The formation of a biofilm on correct supports is critical to immobilised fermentation. In this study, Pichia pastoris was used to understand and control the modification of surface properties of supports and cells. Following deletion of gene PAS_chr2-1_0773, in P. pastoris △0773, the cell-surface negative charge density decreased and hydrophobicity improved, which was conducive to adhesion. Therefore, according to the changing trend of cell surface properties, cotton fibre was used with succinic anhydride (SA) to modify the carrier for changing the surface properties for efficient conduction of immobilised fermentation. In the fermentation process, the adhesion between the modified cotton fibre and yeast was better than that between an unmodified cotton fibre and yeast, and the additive amount increased by ∼25 %. The enzyme activity of the △0773-cotton-SA fermentation system reached 302.7 U/mL, which was 39.6 % higher than that of the original fermentation system. Therefore, this study provides a guide for significant improvement of immobilised fermentation of fungi.

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.

The first total synthesis of (±)-furanether A, which exhibits good antifeedant activity, has been concisely achieved in 13 linear steps. Notably, the key rigid tetracyclic skeleton containing a 1-methyl-8-oxabicyclo[3.2.1]octane moiety with two vicinal quaternary carbon centers was rapidly constructed in one step through a unique tandem C-H oxidation/oxa-[3,3] Cope rearrangement/aldol cyclization sequence.

To effectively immobilize an enzyme while maintaining its high activity and stability, the design of supports with controlled geometric structures and heterogeneous surface properties is desirable. Towards this goal, heterogeneous titanium dioxide (TiO2) surfaces with controlled pore sizes were synthesized in this study and used to efficiently immobilize lipase. The immobilized lipase activity increased by a factor of 1.31 with an increase in the TiO2 pore size from 11.46 to 21.14 nm. The highest protein loading of 15.52 mg/g was achieved in ethenyl triethoxy silane (ETS)-modified TiO2 (E-P25) after immobilizing the enzymes at 30 ℃, pH 7.33 for 3 h and using a protein concentration in solution of 0.176 mg/mL. Among the different surface functionalities, the highest activity yield of 428.04 % was accomplished by using TiO2 calcinated at 650 ℃ and modified by ETS as immobilization support. The immobilized enzymes showed excellent storage stability and retained almost 95 % of their activity after being stored at 4 ℃ for 8 weeks. This research provides experimental evidence that highlights the importance of studying of enzyme immobilization on the supports with synergistically designed geometric structures and surface chemical properties.

A new paraherquamide named aculeaquamide A (1) was isolated from an EtOAc extract of Aspergillus aculeatinus WHF0198 culture media together with five known compounds. The structures of the isolated compounds were elucidated by analysis of NMR and MS data, and the absolute configurations of compound 1 was confirmed by CD spectroscopic methods. All isolated compounds were evaluated for their cytotoxicity against three human cancer cell lines, Bel-7402, A549, and HCT-116. Compounds 1 and 2 showed cytotoxicity against Bel-7402 with IC50 values of 3.3 and 1.9 μM, respectively.

Crystalline solids that exhibit inherently low lattice thermal conductivity (κlat) have attracted a great deal of attention because they offer the only independent control for pursuing a high thermoelectric figure of merit (ZT). Herein, we report the successful preparation of CsCu4Q3 (Q = S (compound 1), Se (compound 2)) with the aid of a safe and facile boron-chalcogen method. The single-crystal diffraction data confirm the P4/mmm hierarchical structures built up by the mixed-valence [(Cu+)4(Q2-)2](Q-) double anti-CaF2 layer and the NaCl-type Cs+ sublattice involving multiple bonding interactions. The electron-poor compound CsCu4Q3 features Cu-Q antibonding states around EF that facilitates a high σ value of 3100 S/cm in 2 at 323 K. Significantly, the ultralow κlat value of 2, 0.20 W/m/K at 650 K (70% lower than that of Cu2Se), is mainly driven by the vibrational coupling of the rigid double anti-CaF2 layer and the soft NaCl-type sublattice. The hierarchical structure increases the bond multiplicity, which eventually leads to a large phonon anharmonicity, as evidenced by the effective scattering of the low-lying optical phonons to the heat-carrying acoustic phonons. Consequently, the acoustic phonon frequency in 2 drops sharply from 118 cm-1 (of Cu2Se) to 48 cm-1. In addition, the elastic properties indicate that the hierarchical structure largely inhibits the transverse phonon modes, leading to a sound velocity (1571 m/s) and a Debye temperature (189 K) lower than those of Cu2Se (2320 m/s; 292 K).

Microbial phosphate removal from wastewater sewage is a promising and feasible technique that increases the ability of a sewage treatment system to remove phosphate from wastewater. Maintaining a healthy population of phosphate-solubilizing bacteria is the key premise of biological sewage treatment. Chitosan is used to remove dissolved phosphorus from the water column during wastewater treatment. The present study found that chitosan has another function in phosphorus removal, affecting the diversity and community composition of phosphate-solubilizing bacteria. We obtained 16S rRNA genetic data by using a shotgun metagenomic sequencing method. Data indicated that phosphate-solubilizing Pseudomonadaceae was the dominant bacteria population, after adding chitosan to the dynamic water treatment process. In chitosan-enhanced treatments, populations were 35.11% larger than the control group. Chitosan addition also caused some increases in the population sizes of Rhodocyclaceae, Bacillaceae, and Enterobacteriaceae, but the addition of chitosan had little effect on Hyphomicrobiaceae and Sphingomonadaceae in the activated sludge. Moreover, the Chao1 estimator, the abundance-based coverage estimator (ACE), and Shannon index all indicated a very high diversity of bacteria when chitosan was added. Finally, we determined that chitosan increased the activity of the enzymes phytase, dehydrogenase, and phosphatase, which enhance the degradation rate of phosphorus in the activated sludge of a D-A2O system. We suggest that chitosan plays an important role in dissolving organophosphorus during sewage treatment. HIGHLIGHTS We report that we found another function of chitosan, that is, chitosan could affect the bacterial diversity and community composition in wastewater treatment.; We solved the problem that to increase the total phosphorus removal efficiency of biological nutrient removal process for wastewater treatment in low temperatures.

Due to the booming development of the automation industry and the transportation industry, the mechanical components are prone to wear under long-term operating conditions. To improve the wear resistance, effects of the rolling directions on wear of the aluminum alloys are studied. An optical microscope is used to analyze the crystal phase, and the correlation between the crystal grains and the rolling direction is studied. This study can therefore establish a key technology for improving the wear resistance of aluminum alloys.

Hard carbons (HC) derived from biomass material are most promising anodes for lithium-ion batteries (LIBs) because of their cost effectiveness and environmental friendliness. However, the low initial Coulombic efficiency (ICE) of HC anodes reduces the energy density of full cells, which seriously impedes their practical applications. Herein, we demonstrate that the ICE of HC anodes can be significantly improved by modulating the work function of a model HC derived from cotton and deliberately treated to form C-Cl bonds on its surface. By X-ray absorption near-edge structure and density functional theory (DFT) calculation studies, it is verified that the introduction of the C-Cl bond leads to the electron transfer from C to Cl and enhances the work function of the system. In addition, this Cl-doped HC anode can inhibit the reduction of solvent molecules in the electrolyte and reduce the formation of a solid electrolyte interface (SEI) film. Consequently, the ICE is improved from 64.8 to 78.1%. This study provides an effective route to reduce the formation of the SEI film and improve the ICE of hard carbon anodes for LIBs.

An efficient preparation and local coordination environment regulation of isolated single-atom sites catalysts (ISASC) for improved activity is still challenging. Herein, we develop a solid phase thermal diffusion strategy to synthesize Mn ISASC on highly uniform nitrogen-doped carbon nanotubes by employing MnO2 nanowires@ZIF-8 core-shell structure. Under high-temperature, the Mn species break free from core-MnO2 lattice, which will be trapped by carbon defects derived from shell-ZIF-8 carbonization, and immobilized within carbon substrate. Furthermore, the poly-dispersed Mn sites with two nitrogen-coordinated centers can be controllably renovated into four-nitrogen-coordinated Mn sites using NH3 treatment technology. Both experimental and computational investigations indicate that the symmetric coordinated Mn sites manifest outstanding oxygen reduction activity and superior stability in alkaline and acidic solutions. This work not only provides efficient way to regulate the coordination structure of ISASC to improve catalytic performance but also paves the way to reveal its significant promise for commercial application.

Designing and modulating the local structure of metal sites is the key to gain the unique selectivity and high activity of single metal site catalysts. Herein, we report strain engineering of curved single atomic iron-nitrogen sites to boost electrocatalytic activity. First, a helical carbon structure with abundant high-curvature surface is realized by carbonization of helical polypyrrole that is templated from self-assembled chiral surfactants. The high-curvature surface introduces compressive strain on the supported Fe-N4 sites. Consequently, the curved Fe-N4 sites with 1.5 % compressed Fe-N bonds exhibit downshifted d-band center than the planar sites. Such a change can weaken the bonding strength between the oxygenated intermediates and metal sites, resulting a much smaller energy barrier for oxygen reduction. Catalytic tests further demonstrate that a kinetic current density of 7.922 mA cm-2 at 0.9 V vs. RHE is obtained in alkaline media for curved Fe-N4 sites, which is 31 times higher than that for planar ones. Our findings shed light on modulating the local three-dimensional structure of single metal sites and boosting the catalytic activity via strain engineering.

Improving carbon emission efficiency (CEE) would promote the development of the green and low-carbon economy in the Beijing-Tianjin-Hebei (BTH) region, China. This paper uses the EBM model of unexpected output to measure the city-level CEE of the BTH region from 2007 to 2016. The spatial distribution characteristics and evolution law of CEE are analyzed with respect to overall and local aspects, and the spatial quantile regression model is used to verify the influencing factors of CEE. The main findings are as follows: (1) The carbon emission in the BTH region is considered to be of medium efficiency, and there are eight cities within the region at middle- and high-efficiency levels. The overall efficiency values show a downward trend. Beijing, Cangzhou, Baoding have high-CEE values, whereas Handan, Tangshan, and Zhangjiakou have low-CEE values. (2) The CEE values for BTH show significant spatial agglomeration characteristics at both the global and local levels. The “H–H” agglomeration areas are primarily distributed in the central region, and the “L-L” agglomeration areas are chiefly distributed in the southern and northern regions. The spatial pattern change is generally stable. (3) The selected factors, URB, PGDP, DS, ISG, FDI, and TEL, have different regression coefficients on CEE at different quantiles.

The lockdown due to COVID-19 created a rare opportunity to examine the nonlinear responses of secondary aerosols, which are formed through atmospheric oxidation of gaseous precursors, to intensive precursor emission reductions. Based on unique observational data sets from six supersites in eastern China during 2019-2021, we found that the lockdown caused considerable decreases (32-61%) in different secondary aerosol components in the study region because of similar-degree precursor reductions. However, due to insufficient combustion-related volatile organic compound (VOC) reduction, odd oxygen (Ox = O3 + NO2) concentration, an indicator of the extent of photochemical processing, showed little change and did not promote more decreases in secondary aerosols. We also found that the Chinese provinces and international cities that experienced reduced Ox during the lockdown usually gained a greater simultaneous PM2.5 decrease than other provinces and cities with an increased Ox. Therefore, we argue that strict VOC control in winter, which has been largely ignored so far, is critical in future policies to mitigate winter haze more efficiently by reducing Ox simultaneously.

To use vanadium–titanium magnetite (VTM) resources for sintering, a composite agglomeration process (CAP) is applied. This paper studies the effects of pelletizing parameters, including particle si...

An efficient synthesis of indolo[2,1-a]benzazepinones through rhodium-catalyzed cascade reactions of 2-arylindoles with allyl alcohols has been developed. This work expands the scope of products that are available through C-H activation/intramolecular annulation reactions of 2-arylindoles in organic synthesis.

The Rh(III)-catalyzed dual directing group assisted C-H activation/annulation of 3-arylisoxazolones with propargyl alcohols has been developed, which expands the application scope of isoxazolones in organic synthesis. This protocol also worked well with 3-aryl-1,4,2-dioxazol-5-ones to produce synthetically and biologically important 4-arylisoquinolones.

Industrially, lignin in pulp liquor not only obstructed the realization of value-added products, but also threatened the aquatic ecosystem. A magnetic composite Ca(OH)2/Fe3O4, combining the eco-friendliness of Ca-based flocculants with the convenience of magnetic flocculation, was simply compounded to efficiently flocculate lignin from papermaking black liquor. Morphologic and structural features of the flocculant before and after flocculation were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). The flocculant Ca(OH)2/Fe3O4 presented mesoporous and core-shell structure, which acted directly in the sodium lignin aqueous solution without pH neutralization, maintaining high lignin removal between 91% and 95%. Ca(OH)2/Fe3O4 showed a wider salts (0–1 mol/L NaCl) and pH (9–12.5) tolerance. In actual pulp black liquor, Ca(OH)2/Fe3O4 exhibited high removal of 90.16% and 85.93% for lignin and chemical oxygen demand (COD), respectively. The flocculation performance of Ca(OH)2/Fe3O4 outdistanced that of the traditional flocculant polyacrylamide (PAM). It displayed magnetically separable with a good reusability. The removal of lignin could attain 90.54% even after 6 cycles. Charge neutralization, micro-bridging, destabilization and sedimentation were involved in the process of lignin flocculation. Consequently, Ca(OH)2/Fe3O4 presented huge potential in papermaking black liquor treatment.

In the ironmaking process, the addition of an organic binder to replace a portion of bentonite has the potential to improve the performance of pellets. The interaction between original bentonite (OB) and organic binder was investigated. Results indicated that the micromorphology of organic composite bentonite (OCB) became porous and the infrared difference spectrum exhibited a curved shape. In addition, the residual burning rates of OB and organic binder were determined to be 82.72% and 2.30%, respectively. Finally, the influence of OCB on the properties of pellets was investigated. The compressive strength of OCB-added green pellets (14.7 N per pellet) was better than that of OB-added pellets (10.3 N per pellet). Moreover, the range of melting temperature of OCB-added green pellets (173°C) was narrower than that of OB-added pellets (198°C). The compressive strength of OCB-added green pellets increased from 2156 to 3156 N per pellet with the increase in roasting temperature from 1200 to 1250°C.

Shoot-tip abortion is a very common phenomenon in some perennial woody plants and it affects the height, architecture, and branch orientation of trees; however, little is currently known about the underlying mechanisms. In this study, we identified a gene in sweet orange (Citrus sinensis) encoding a KNAT-like protein (CsKN1) and found high expression in the shoot apical meristem (SAM). Overexpression of CsKN1 in transgenic plants prolonged the vegetative growth of SAMs, whilst silencing resulted in either the loss or inhibition of SAMs. Yeast two-hybrid analysis revealed that CsKN1 interacted with another citrus KNAT-like protein (CsKN2), and overexpression of CsKN2 in lemon and tobacco caused an extreme multiple-meristem phenotype. Overexpression of CsKN1 and CsKN2 in transgenic plants resulted in the differential expression of numerous genes related to hormone biosynthesis and signaling. Yeast one-hybrid analysis revealed that the CsKN1-CsKN2 complex can bind to the promoter of citrus floral meristem gene LEAFY (CsLFY) and inhibit its expression. These results indicated that CsKN1 might prolong the vegetative growth period of SAMs by delaying flowering. In addition, an ethylene-responsive factor (CsERF) was found to bind to the CsKN1 promoter and suppresses its transcription. Overexpression of CsERF in Arabidopsis increased the contents of ethylene and reactive oxygen species, which might induce the occurrence of shoot-tip abscission. On the basis of our results, we conclude that CsKN1 and CsKN2 might work cooperatively to regulate the shoot-tip abscission process in spring shoots of sweet orange.

Herein, the catalytic properties and reaction mechanisms of the 3d, 4d, and 5d transition metals embedded in 2D rectangular tetracyanoquinodimethane (TM-rTCNQ) monolayers as single-atom catalysts (SACs) for the electrocatalytic N2 reduction reaction (NRR) were systematically investigated, using first-principles calculations. A series of high-throughput screenings were carried out on 30 TM-rTCNQ monolayers, and all possible NRR pathways were explored. Three TM-rTCNQ (TM = Mo, Tc, and W) SACs were selected as promising new NRR catalyst candidates because of their high structural stability and good catalytic performance (low onset potential and high selectivity). Our results show that the Mo-rTCNQ monolayer can catalyze NRR through a distal mechanism with an onset potential of -0.48 V. Surprisingly, the NH3 desorption energy on the Mo-rTCNQ monolayer is only 0.29 eV, the lowest one reported in the literature so far, which makes the Mo-rTCNQ monolayer a good NRR catalyst candidate. In-depth research studies on the structures of N2-TM-rTCNQ (TM = Mo, Tc, and W) found that strong adsorption and activation performance of TM-rTCNQ for N2 may be due to the strong charge transfer and orbital hybridization between the TM-rTCNQ catalyst and the N2 molecules. Our work provides new ideas for achieving N2 fixation under environmental conditions.

Inflammatory bowel disease (IBD), which mainly includes ulcerative colitis (UC) and Crohn's disease (CD), is a group of chronic bowel diseases that are characterized by abdominal pain, diarrhea, and bloody stools. IBD is strongly associated with depression, and its patients have a higher incidence of depression than the general population. Depression also adversely affects the quality of life and disease prognosis of patients with IBD. The tryptophan-kynurenine metabolic pathway degrades more than 90% of tryptophan (TRP) throughout the body, with indoleamine 2,3-dioxygenase (IDO), the key metabolic enzyme, being activated in the inflammatory environment. A series of metabolites of the pathway are neurologically active, among which kynerunic acid (KYNA) and quinolinic acid (QUIN) are molecules of great interest in recent studies on the mechanisms of inflammation-induced depression. In this review, the relationship between depression in IBD and the tryptophan-kynurenine metabolic pathway is overviewed in the light of recent publications.

Inorganic mesoporous silica gel spheres, which possess sufficient mechanical strength, thermal stability, and mobile phase endurance, are the most important and widely used materials for column packing in high performance liquid chromatography (HPLC). However, amorphous silica gel is generally reported as an inorganic chiral silica gel, and spherical all-inorganic chiral silica gel has not been reportedly used as the chiral stationary phase for HPLC. In this paper, inorganic spherical mesoporous silica gel was used in the method of polymerization-induced colloid aggregation (PICA), with silica sol as the raw material and L-glutamic acid (L-Glu) as the chiral monomer, to obtain mixed spheres of urea-formaldehyde resin and colloidal silica in a chiral environment. After high-temperature calcination (at 550 ℃) to remove the resin, inorganic mesoporous silica gel spheres based on L-Glu were prepared. Elemental analysis revealed that the prepared L-Glu chiral silica gel spheres were calcined completely, indicating that there were no organic constituents. Scanning electron microscopy (SEM) images of the silica gel spheres showed that the surface of the silica gel spheres was not smooth, with a uniform particle size of 3.0-4.5 μm. Transmission electron microscopy (TEM) images showed that the pore size distribution of the synthetic silica gel spheres was uniform due to the accumulation of pores. Nitrogen adsorption tests revealed that the specific surface area of L-Glu chiral silica gel spheres was 117.844 m2/g, the pore volume was 0.411 cm3/g, and the average pore size was 12.312 nm. All the characterizations indicated that the inorganic chiral mesoporous silicon had a regular spherical shape. The silica gel spheres possess frameworks and pore structures, providing a chiral microenvironment that is suitable as a chiral stationary phase for separating racemic compounds by HPLC. Because of the chiral pore structure and frameworks, the enantiomers were retained to different degrees and separation was achieved. The porous structure also increased the contact surface between the racemates and the active sites of the inner wall and improved the separation efficiency. Hydrogen bonding between the chiral stationary phase and the racemates, dipole interactions, and van der Waals forces were also involved in enantiomer resolution. An HPLC column was prepared with L-Glu chiral silica gel as the stationary phase and n-hexane-isopropanol (9∶1, v/v) as the mobile phase. Fifteen racemic compounds were successfully separated on the chiral HPLC column, including seven racemic compounds for baseline separation, at a flow rate of 0.1 mL/min using 254 nm as the detection wavelength at 25 ℃. The separation of 10 benzene position isomers was successfully achieved, and eight of the benzene position isomers reached baseline separation. Experimental results showed that the chiral silica gel spheres possess sufficient mechanical strength and thermal stability, along with good chiral recognition ability and the ability to separate positional isomers. Compared with ordinary silica gel, these chiral silica gel spheres afforded better chiral separation and better separation of benzene position isomers, without further modification. The preparation of this chiral stationary phase also has the advantages of being cheap, convenient, and feasible.

To increase the drug loading and prolong the drug release time, novel hollow organic/inorganic hybrid nanoparticles based on dextran-b-poly(L-glutamate-graft-3-mercaptopropyltrimethoxysilane) (Dex-b-P(ALG-g-MTPMS)) were prepared. First, a polysaccharide block polypeptide diblock copolymer, dextran-block-poly(γ-allyl-L-glutamate) (Dex-b-PALG) bearing allyl side-groups, has been synthesized by the combination of ring-opening polymerization and alkyne-azide [2 + 3] Huisgen's cycloaddition. Next, the allyl side-groups residing in the poly(γ-allyl-L-glutamate) block were further functionalized with 3-mercaptopropyltrimethoxysilane(MPTMS) by radical "thiol-ene" addition reactions. Finally, after a sol-gel process of the obtained copolymers, the novel organic/inorganic hybrid nanoparticles were prepared. The molecular structures, physicochemical, and self-assembly of these copolymers were characterized through FTIR, 1H NMR, dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The cross-linked hybrid nanoparticles have a higher drug loading ability and slower release rate as compared to the uncross-linked counterparts. The MTT evaluation demonstrated that the organic/inorganic hybrid nanoparticles with good biocompatibility.

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.