Super-Assembled Chiral Mesostructured Heteromembranes for Smart and Sensitive Couple-Accelerated Enantioseparation.

In the context of sustainable development, chirality, especially chiral drugs, has attracted great interest in the pharmaceutical industry, yet the smart and sensitive separation of enantiomers still presents a major scientific challenge. Herein, inspired by supramolecular templating via chiral transcription nanoparticles, an artificial chiral nanochannel membrane with asymmetric structure, porosity, and abundant chiral surface is fabricated for smart and sensitive enantiomer recognition and separation. Constructed from chiral transcript mesoporous silica (CMS) super-assembled on a porous anode alumina oxide (AAO) support, the obtained heterostructured chiral membrane (CMS/AAO) exhibits enhanced enantioseparation (approximately 170% compared to the supramolecular-templated nanoparticles) among a series of amino acids with various isoelectric points (PIs). Especially for amino acids with a PI greater than 7, the couple-accelerated enantioseparation (CAE) can be achieved for the first time. Further analysis using an osmotic energy conversion test and simulations based on the Poisson-Nernst-Planck (PNP) equations confirm that the heterostructure and charge polarity are the key to achieve chiral amino acids and ion separation. We expect this work will inspire the development of multifunctional membrane systems for more sustainable and energy-efficient enantioseparation.

Enhancing light emission of Si nanocrystals by means of high-pressure hydrogenation.

High-density Si nanocrystal thin film composed of Si nanocrystals and SiO2, or Si-NCs:SiO2, was prepared by annealing hydrogen silsesquioxane (HSQ) in a hydrogen and nitrogen (H2:N2=5%:95%) atmosphere at 1100°C. Conventional normal-pressure (1-bar) hydrogenation failed to enhance the light emission of the Si-NCs:SiO2 sample made from HSQ. High-pressure hydrogenation was then applied to the sample in a 30-bar hydrogen atmosphere for this purpose. The light emission of Si-NCs increased steadily with increasing hydrogenation time. The photoluminescence (PL) intensity, the PL quantum yield, the maximal electroluminescence intensity, and the optical gain were increased by 90%, 114%, 193% and 77%, respectively, after 10-day high-pressure hydrogenation, with the PL quantum yield as high as 59%, under the current experimental condition.

Rational design of covalent organic frameworks/NaTaO3 S-scheme heterostructure for enhanced photocatalytic hydrogen evolution.

As a typical perovskite material, NaTaO3 has been regarded as a potential catalyst for photocatalytic hydrogen evolution (PHE) process, due to its excellent photoelectric property and superior chemical stability. However, the photocatalytic activity of pure NaTaO3 was largely restricted by its poor visible-light absorption ability and rapid recombination of photogenerated charge carriers. Therefore, a covalently bonded TpBpy covalent organic framework (COF)/NaTaO3 (TpBpy/NaTaO3) heterostructure was designed and synthesized by the post modification strategy with (3-aminopropyl) triethoxysilane (APTES) and the in situ solvothermal process. Benefiting from the enhanced built-in electric field by the interfacial covalent bonds and the formation of S-scheme heterostructure between TpBpy and NaTaO3, which were proved by the Ar+-cluster depth profile and X-ray photoelectron spectroscopy (XPS), as well as density functional theory (DFT) calculation results, both the charge transfer efficiency and the PHE performance of the TpBpy/NaTaO3 composites were significantly improved. Additionally, the composites exhibited an excellent absorption performance in the visible region, which was also beneficial for the photocatalytic process. As expected, the optimal TpBpy/20%NaTaO3 composite achieved a remarkable hydrogen evolution rate of 17.3 mmol·g-1·h-1 (10 mg of catalyst) under simulated sunlight irradiation, which was about 173 and 2.4 times higher than that of pure NaTaO3 and TpBpy, respectively. This work provided a novel strategy for constructing highly effective and stable semiconductor/COFs heterostructures with strong interfacial interaction for photocatalytic hydrogen evolution.

pH Modulation of Super-Assembled Heteromembranes for Sustainable Chiral Sensing.

Enantioselective sensing and separation represent formidable challenges across a diverse range of scientific domains. The advent of hybrid chiral membranes offers a promising avenue to address these challenges, capitalizing on their unique characteristics, including their heterogeneous structure, porosity, and abundance of chiral surfaces. However, the prevailing fabrication methods typically involve the initial preparation of achiral porous membranes followed by subsequent modification with chiral molecules, limiting their synthesis flexibility and controllability. Moreover, existing chiral membranes struggle to achieve coupled-accelerated enantioseparation (CAE). Here, we report a replacement strategy to controllably produce mesoscale and chiral silica-carbon (MCSC) hybrid membranes that comprise chiral pores by interfacial superassembly on a macroporous alumina (AAO) membrane, in which both ion- and enantiomers can be effectively and selectively transported across the membrane. As a result, the heterostructured hybrid membrane (MCSC/AAO) exhibits enhanced selectivity for cations and enantiomers of amino acids, achieving CAE for amino acids with an isoelectric point (pI) exceeding 7. Interestingly, the MCSC/AAO system demonstrates enhanced pH-sensitive enantioseparation compared to chiral mesoporous silica/AAO (CMS/AAO) with significant improvements of 78.14, 65.37, and 14.29% in the separation efficiency, separation factor, and permeate flux, respectively. This work promises to advance the synthesis of two or more component-integrated chiral nanochannels with multifunctional properties and allows a better understanding of the origins of the homochiral hybrid membranes.

De novo design of DNA aptamers that target okadaic acid (OA) by docking-then-assembling of single nucleotides.

Okadaic acid (OA) is a diarrhetic shellfish poison widespread in ocean, so its detection is of great significance to seafood safety. Because of good sensitivity and low cost, biosensors using nucleic-acid aptamers as the recognition molecules are emerging as an important detection tool. However, the traditional SELEX screening method for acquiring OA high-affinity aptamers is time- and resource-intensive. Alternatively, here we developed a de novo design method based on the 3D structure of a target molecule, such as OA. Without experimental screening, this method designs OA aptamers by a computational approach of docking-then-assembling (DTA) of single nucleotides (A, C, G and T) as: (1) determining the high-affinity nucleotide binding sites of the target molecule via saturated molecular docking; (2) assembling the bound nucleotides into binding units to the target molecule; (3) constructing full-length aptamers by introducing stabilizing units to connect these binding units. In this way, five OA aptamers were designed, and microscale thermophoresis (MST) experiments verified that their Kd values are in the range of 100-600 nM; and one of them (named 9CGAT_4_a) could specifically bind to OA with low affinities for the other three marine biotoxins. Therefore, this study provides high-affinity and specific aptamers for the development of OA biosensors, and presents a promising de novo design method applicable to other target molecules.

Repurposing of thermally stable nucleic-acid aptamers for targeting tetrodotoxin (TTX).

Tetrodotoxin (TTX) is a lethal neurotoxin produced by the endosymbiotic bacteria in the gut of puffer fish. Currently, there is no effective and economical method to detect TTX, so it is very interesting to develop low-cost and high-sensitivity detection methods by using nucleic-acid aptamers as the recognition molecules. However, traditional SELEX screening of aptamers for targeting small molecules such as TTX is labor-intensive, and usually the success rate is low. Here, we employed a strategy of "repurposing old aptamers for new uses" to develop high-affinity aptamers for TTX. To this end, we first collected thermally stable DNA aptamers and predicted their affinities for TTX by molecular docking; then, we identified high-affinity candidates and verified them by microscale thermophoresis (MST) experiments. In this way, two thermally stable aptamers (Tv-51 and AI-57) were found to possess nanomolar affinities for TTX. Moreover, we performed spontaneous binding simulations to reveal their binding mechanisms to TTX and thereby identified the key bases for the binding. Guided by these, two variants (Tv-46 and AI-52) with higher affinities and specificities were subsequently engineered and confirmed by the MST experiments. So, this study not only provides potential recognition molecules for the technology developments of TTX detection, but also demonstrates an effective repurposing approach to the discovery of high-affinity aptamers for new target molecules.

Cardio-protective and Anti-atherosclerosis Effect of Crocetin on Vitamin D3 and HFD-induced Atherosclerosis in Rats.

Cardiovascular disease (CVD) is a chronic disease and causes the highest rate of death globally. CVD-related deaths account for 80% of all deaths in low and middle-income countries, such as China. Crocetin (CT), a carotenoid phytoconstituent already confirm their anti-inflammatory and antioxidant effects in various diseases animal models. In the study, we make effort to access the cardio-protective effect of Crocetin against vitamin D3 and high fat induced atherosclerosis in rats and scrutinize the underlying mechanism. Sprague Dawley (SD) rats were used in this study and rats were divided into different groups and high fat diet and vitamin D was used for induction the atherosclerosis. The rats were received oral administration of crocetin (5, 10 and 15 mg/kg) and simvastatin (0.5 mg/kg) until 30 days. At the end of the experimental period, lipid, cardiac markers, anti-inflammatory, antioxidant, pro-inflammatory cytokines and atherogenic index were estimated. The mRNA expression of Intercellular adhesion molecule-1 (ICAM-1), Monocyte Chemoattractant Protein-1 (MCP-1) and vascular cell adhesion molecule 1 (VCAM-1) in aortic tissue of the atherosclerotic rats. Crocetin significantly reduced the aortic membrane thickness and platelet aggregation rates. Crocetin also dose-dependently reduced total cholesterol (TC), very low-density lipoprotein (VLDL), triacylglycerol (TG), low-density lipoprotein (LDL) and augmented the level of high-density lipoprotein (HDL) level. Additionally, Crocetin significantly (p < 0.001) abridged the level of malonaldehyde (MDA) and augmented the level of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and glutathione peroxidase (GPx). Furthermore, Crocetin significantly (p < 0.001) dose-dependently reduced the levels of pro-inflammatory cytokines and inflammatory mediators. Crocetin attenuated mRNA expression of VCAM-1, ICAM-1 and MCP-1. Crocetin had anti-atherosclerosis and cardio-protective effects on vitamin D3 and high fat induced atherosclerosis in rats through anti-inflammatory and antioxidant mechanisms.

[Role of macrophages in mouse uterine during the peri-implantation period].

OBJECTIVE: To investigate the effect of macrophages on embryo implantation by observing the distribution of macrophages in mouse uterine tissues during the peri-implantation period. METHODS: Uterine tissues were collected from pregnant (n=30) and pseudopregnant mice (n=30) during the peri-implantation period. The distributions of macrophages, iNOS and leukemia inhibitory factor (LIF) were determined by immunohistochemistry and the correlations of macrophages with iNOS and LIF were analyzed. RESULTS: Macrophages were located mainly in the endometrium before D4.5 in the pregnant rats with D0.5 defined as the morning when a vaginal plug was observed. After D4.5, the macrophages was significantly reduced in number (P<0.05) in the endometrium and gradually migrated to the perimetrium. In the psudopregnant mice, macrophages were located mainly in the endometrium. Before D4.5, iNOS-positive cells were detected mainly in the endometrium and the myometrium in the pregnant rats and became significantly reduced on D4.5 (P<0.05); in the pseudopregnant mice, the positive cells were mostly detected in the endometrium. Significant differences were found in the distribution of the macrophages and LIF between the implantation and non-implantation sites (P=0.013). LIF was mostly located in the endometrium in the pregnant mice but scarcely detected in the pseudopregnant mice. CONCLUSION: Macrophages are located mainly in the endometrium and the implantation site where iNOS and LIF are expressed, suggesting the important role of macrophages in the determination of implantation.

Coke- and sintering-resistant monolithic catalysts derived from in situ supported hydrotalcite-like films on Al wires for dry reforming of methane.

Monolithic catalysts derived from in situ supported hydrotalcite-like films on Al wires display high resistance to coke formation and sintering in the dry reforming of methane due to their hierarchical porous structure, well dispersed metallic nickel species, more basic sites and strong metal-support interaction effect.

Design of modular catalysts derived from NiMgAl-LDH@m-SiO2 with dual confinement effects for dry reforming of methane.

The modular catalysts were fabricated via the combination of the Ni-MgO-Al2O3 mixed oxide nanoplates and the mesoporous SiO2 coating. Due to the dual confinements, the catalysts show high catalytic activity with enhanced coke- and sintering-resistance in the dry reforming of methane reaction.

In situ supported MnO(x)-CeO(x) on carbon nanotubes for the low-temperature selective catalytic reduction of NO with NH3.

The MnO(x) and CeO(x) were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH(3). X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H(2) temperature-programmed reduction (H(2)-TPR) and NH(3) temperature-programmed desorption (NH(3)-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H(2)-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH(3)-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO(2)-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.

Low-temperature selective catalytic reduction of NO with NH3 over nanoflaky MnOx on carbon nanotubes in situ prepared via a chemical bath deposition route.

Nanoflaky MnO(x) on carbon nanotubes (nf-MnO(x)@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH3. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD). The SEM, TEM, XRD results and N2 adsorption-desorption analysis indicated that the CNTs were surrounded by nanoflaky MnO(x) and the obtained catalyst exhibited a large surface area as well. Compared with the MnO(x)/CNT and MnO(x)/TiO2 catalysts prepared by an impregnation method, the nf-MnO(x)@CNTs presented better NH3-SCR activity at low temperature and a more extensive operating temperature window. The XPS results showed that a higher atomic concentration of Mn(4+) and more chemisorbed oxygen species existed on the surface of CNTs for nf-MnO(x)@CNTs. The H2-TPR and NH3-TPD results demonstrated that the nf-MnO(x)@CNTs possessed stronger reducing ability, more acid sites and stronger acid strength than the other two catalysts. Based on the above mentioned favourable properties, the nf-MnO(x)@CNT catalyst has an excellent performance in the low-temperature SCR of NO to N2 with NH3. In addition, the nf-MnO(x)@CNT catalyst also presented favourable stability and H2O resistance.

Design of meso-TiO2@MnO(x)-CeO(x)/CNTs with a core-shell structure as DeNO(x) catalysts: promotion of activity, stability and SO2-tolerance.

Developing low-temperature deNOx catalysts with high catalytic activity, SO2-tolerance and stability is highly desirable but remains challenging. Herein, by coating the mesoporous TiO2 layers on carbon nanotubes (CNTs)-supported MnOx and CeOx nanoparticles (NPs), we obtained a core-shell structural deNOx catalyst with high catalytic activity, good SO2-tolerance and enhanced stability. Transmission electron microscopy, X-ray diffraction, N2 sorption, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction and NH3 temperature-programmed desorption have been used to elucidate the structure and surface properties of the obtained catalysts. Both the specific surface area and chemisorbed oxygen species are enhanced by the coating of meso-TiO2 sheaths. The meso-TiO2 sheaths not only enhance the acid strength but also raise acid amounts. Moreover, there is a strong interaction among the manganese oxide, cerium oxide and meso-TiO2 sheaths. Based on these favorable properties, the meso-TiO2 coated catalyst exhibits a higher activity and more extensive operating-temperature window, compared to the uncoated catalyst. In addition, the meso-TiO2 sheaths can serve as an effective barrier to prevent the aggregation of metal oxide NPs during stability testing. As a result, the meso-TiO2 overcoated catalyst exhibits a much better stability than the uncoated one. More importantly, the meso-TiO2 sheaths can not only prevent the generation of ammonium sulfate species from blocking the active sites but also inhibit the formation of manganese sulfate, resulting in a higher SO2-tolerance. These results indicate that the design of a core-shell structure is effective to promote the performance of deNOx catalysts.

Shape-controlled synthesis and catalytic application of ceria nanomaterials.

Because of their excellent properties and extensive applications, ceria nanomaterials have attracted much attention in recent years. This perspective provides a comprehensive review of current research activities that focus on the shape-controlled synthesis methods of ceria nanostructures. We elaborate on the synthesis strategies in the following four sections: (i) oriented growth directed by the crystallographic structure of cerium-based materials; (ii) oriented growth directed by the use of an appropriate capping reagent; (iii) growth confined or dictated by various templates; (iv) other potential methods for generating CeO(2) nanomaterials. In this perspective, we also discuss the catalytic applications of ceria nanostructures. They are often used as active components or supports in many catalytic reactions and their catalytic activities show morphology dependence. We review the morphology dependence of their catalytic performances in carbon monoxide oxidation, water-gas shift, nitric oxide reduction, and reforming reactions. At the end of this review, we give a personal perspective on the probable challenges and developments of the controllable synthesis of CeO(2) nanomaterials and their catalytic applications.

In situ synthesis of 3D flower-like NiMnFe mixed oxides as monolith catalysts for selective catalytic reduction of NO with NH3.

Novel 3D flower-like NiMnFe mixed oxides as monolith catalysts prepared by an in situ hydrothermal method show enhanced performance for the selective catalytic reduction of NO with NH(3).

[Value of serum estradiol concentration in predicting the clinical outcome of IVF-ET in patients receiving long protocol of GnRHa].

OBJECTIVE: To investigate the value of serum estradiol increment and serum estradiol/follicles on the day of hCG administration in predicting the clinical outcomes of in vitro fertilization-embryo transfer (IVF-ET). METHODS: A retrospective analysis of the IVF-ET data was conducted involving 121 patients who received a long gonadotrophin-releasing hormone agonist (GnRHa) protocol. According to the increment of serum estradiol on the day of hCG administration (relative to the level on the day before hCG administration), the patients were divided into 3 groups (A1, A2 and A3) with a increment ratio below 30%, between 30% and 50%, and over 50%, respectively. In addition, according to the ratio of serum estradiol level on hCG day to mature follicle (diameter ≥ 14 mm) number, these patients were divided into three groups (B1, B2 and B3) with the ratio below 250 pg/ml, between 250 and 350 gp/ml, and over 350 pg/ml, respectively. The hormonal characteristics and clinical outcomes of the IVF-ET cycles were analyzed comparatively. RESULTS: Both the clinical pregnancy rate (71.05%) and embryo implantation rate (52.63%) were significantly higher in group A3 than in groups A1 and A2 (P<0.05). The best clinical pregnancy rate (67.86%) and embryo implantation rate (49.14%) were significantly higher in group B2 than in groups B1 and B3 (P<0.05). CONCLUSION: The variation of serum estradiol shows an important impact on the clinical outcomes of IVF-ET in patients receiving long GnRH-a protocol. Favorable outcomes can be expected with a hCG day serum estradiol increment ratio above 50% and E(2)/follicle ratio between 250 and 350 pg/ml.

[Analysis of the clinical outcomes of 160 patients undergoing repeated IVF/ICSI-ET treatment].

OBJECTIVE: To study the clinical factors affecting the outcomes of repeated assisted reproductive technology (ART) cycles. METHODS: A retrospective analysis of the clinical data and outcomes was conducted among 160 patients undergoing repeated IVF/ICSI-ET treatment between January 2006 and April 2009. RESULTS: The patients with successful clinical pregnancy after two ART cycles (group A) had a younger age and shorter duration of infertility, and had more antral follicles (AFC), more eggs and good-quality embryos with more transferred embryos available and higher good-quality embryo rate (P<0.05) than those who failed to have pregnancy after the cycles (group B). In the second cycle, the patients in group A had higher doses of short-acting GnRHa, r-HCG and HMG and at the same time more good eggs and embryos than in the first cycle. CONCLUSIONS: Female age is one of the most important factors affecting the pregnancy rate after repeated ART cycles. The clinical pregnancy rate can be enhanced by administering short-acting GnRHa, HMG, oral contraceptives and adjusting the dose of Gn as well as changing the culture medium of embryos.