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At present, the separation of racemates is still a great challenge due to their similarity in chemical structures and physicochemical properties. Here, we proposed a new strategy to improve the enantioseparation performances of graphene oxide (GO) based membranes via controlling the degree of functionalization (DF) of GO by the aid of an epoxide ring-opening reaction with a carboxyl-terminated ionic liquid (IL-COOH) as a spacer, followed by an amidation reaction of the l-glutamic acid (GO-IL-Glu) as chiral selectors. Results show that: i) these membranes are superior in the enantioselectivity and 1–3 orders of magnitude higher in the flux than traditional chiral separation membranes; ii) compared with l-glutamic acid modified GO membranes and their complex membranes with polypeptides in our previous work, they afford a ca. 40–80% increase in enantioselectivities and an order of magnitude increase in fluxes. Herein, IL-COOH groups can not only serve as a spacer, which is propitious to expanding the interlayer spacing of GO-IL-Glu nanosheets, thereby achieving high throughput of enantiomers, but also function as an active site to improve the grafting amount of chiral selectors (l-Glu), helpful for enhancing enantioselectivities. In particular, the flux is not compromised by the improved enantioselectivity in such membranes; on the contrary, it has an order of magnitude increase. Our findings suggest that the strategy used in this work, i.e., combining more chiral selectors with a wider interlayer spacing, could provide new opportunities for simultaneously facilitating high-flux and high-selectivity and a potential application in a great many enantio- and bio-separations.

At present, the separation of racemates is still a great challenge, since they are enantiomers, having similar chemical structures and physical properties. Here, we proposed a new strategy for efficiently separating chiral compounds, i.e., stereoselectively hydrolyzing the individual enantiomer of racemates via enzyme, followed by a simple magnetic separation using Fe3O4 nanoparticles, may implement a complete resolution of racemates. In this work, d-aminoacylase was selected as enzyme, and phenylalanine and methionine as chiral models. The use of d-aminoacylase can hydrolyze d-enantiomer, while l-enantiomer cannot. Magnetic nanoparticles of Fe3O4@SiO2-NH2-COOH composites were designed and synthesized for the amidation reaction with the hydrolyzed d-amino acids from the mixture. With the help of a magnetic field, d-form amino acids can be readily separated at a large scale and the resultant resolving performances indicated that this method exhibited a higher selectivity, compared with common chiral separation techniques. The enantiomeric excess (e.e.) values are 75% and 98% for racemic N-acyl-phenylalanine and methionine, respectively, which solely rely on the hydrolysis capability of used enzymes. This result suggests that our method is feasible, simple, easy to scale-up and high-efficient for the chiral resolution. These findings demonstrate that this strategy could provide new opportunities for improving enantioseparation performances for a host of enantio- and bio-substance with both high-yield and high-selectivity.

Along with its outstanding antidepressant effect, electroconvulsive shock (ECS) can induce learning and memory impairment. Propofol and ketamine have shown to be useful in alleviating the learning and memory impairment. Nevertheless, the mechanism still remains unclear. This study investigated the role of NMDA receptor (NMDAR)-mediated metaplasticity in the learning and memory impairment induced by ECS, as well as the neuroprotective effect of propofol and ketamine in depressive rats. Rats received ECS or ECS under anesthetics after chronic unpredictable mild stress procedure. Long-term potentiation (LTP) was tested by extracellular recording. LTD/LTP threshold was assessed by stimulation of different frequencies. Additionally, NMDAR-mediated field excitatory postsynaptic potential (fEPSP) and NMDAR input/output relationship were detected under hippocampal slice perfusion. Results showed that propofol or low-dose ketamine could partially alleviate ECS-induced LTP impairment, while propofol combined with low-dose ketamine almost reversed the LTP impairment. LTP under ECS was increased by stronger stimulation. ECS could up-regulated LTD/LTP threshold, while propofol or ketamine could down-regulate it. Moreover, ECS activated NMDAR, while propofol and ketamine could inhibit the activation of NMDAR. NMDAR input/output relationship decrease was induced by preconditioning (an analog of ECS in hippocampal slice), however, NMDAR input/output relationship increased by propofol or ketamine. In conclusion, ECS-induced cognitive impairment is caused by NMDAR-mediated metaplasticity via up-regulation of LTD/LTP threshold. Propofol or ketamine alleviates the cognitive impairment, possibly by down-regulating the threshold via inhibition of NMDAR activation induced by ECS.

Electroconvulsive therapy (ECT) is one of the most effective treatments for depressive disorder. Sub-anesthetic dose of ketamine exerts a rapid and robust antidepressive effect. However, it is still unclear whether ketamine usage in ECT is efficacious as an antidepressant. We aimed to conduct a systematic review and meta-analysis on the effects of ketamine in ECT among patients with depressive disorder. MEDLINE, EMBASE, the CENTRAL and PsycINFO for randomized controlled trials were searched to assess the effects of ketamine used in ECT until 31 Mar 2018 (PROSPERO: CRD42018081024). Sixteen studies including 928 patients were enrolled. At the end of ECT, no significant standardized mean difference (SMD) was observed in favor of the ketamine group. Depressive scores were lower in the ketamine group after 1st ECT and 3rd to 6th ECTs. The depressive scores were lower after 2nd, 3rd, 4th and 6th ECTs when the ketamine was used as an add-on anesthetic, while the depressive scores were lower after 1st ECT when ketamine alone was used. Ketamine in ECT showed no better response and remission rate, while increased adverse events, especially related to cardiovascular and psychiatric systems, during the whole ECT course. In conclusion, although ketamine used in ECT cannot reduce the depressive symptoms at the end of treatment, it could accelerate the antidepressive effect in depressive patients receiving ECT, especially in those who used ketamine as an add-on anesthetic. However, ketamine cautiously needs to be administered in ECT due to the possibility of increased risk of side effects.

A new type of porous carbon/MnO2 composites, having bicontinuous structures, i.e., continuous channels and carbon skeletons, was prepared using a phase separation method, followed by a carbonization procedure and a subsequent redox reaction. In this work, such composite electrodes show a high specific capacitance of ca. 260 F g−1 at 0.5 A g−1 in 1 M Na2SO4 aqueous solution, a superior cycling stability (~80% retention after 2000 cycles) and a distinctive high-rate performance. Especially, unique bicontinuous structures endow such composites with a great specific capacitance of the constituent MnO2 (~1100 F g−1), very close to the theoretical value. These excellent electrochemical behaviors may render this material a promising candidate as high-performance electrodes in supercapacitors. Therefore, our findings suggest that the strategy for constructing bicontinuous hybrid electrodes represents an exciting direction for designing next-generation supercapacitors.

A new type of the dimeric imidazolium-type amphiphile, BDBCmIB (m = 1, 4 and 8), was synthesized using the bipyridiyl as the spacer, and its inhibition performance and mechanism for the corrosion of N80 carbon steel in 1.0 mol·L−1 HCl were evaluated using chemical and electrochemical measurements, surface analyses and density functional theory (DFT) calculations. Results show that the inhibition efficiency of BDBCmIBs increases with their concentrations and the length of tail chains. BDBC8IB exhibits the best inhibition performance among them and its inhibition efficiency almost exceeds 90% in a wide concentration range from 1.0 × 10−6 to 5.0 × 10−4 mol·L−1 mol·L−1 at 25.0 °C, which attains the maximum over 95% at 5.0 × 10−4 mol·L−1. Moreover, three BDBCmIBs all display the high inhibition efficiency at 5.0 × 10−4 mol·L−1, nearly exceeding 90%, in the temperature range from 25.0 to 55.0 °C. As a mixed-type inhibitor, BDBCmIBs can retard both cathodic hydrogen evolution and anodic metal dissolution processes, since BDBCmIB molecules bear the imidazolium-based heterocycle with the electron-donating ability and the bipyridine with the electron-accepting ability, thereby facilitating the formation of a protective film on the surface of N80 carbon steel via electrostatic interactions, coordinated and back-donating bonds. The adsorption of BDBCmIBs obeys the Langmuir isothermal model. Our finding demonstrates that the introduction of the bipyridiyl at the spacer does favor improving the inhibition efficiency of such dimeric imidazolium-type amphiphiles, and meanwhile, the proper increase in the number of carbon atoms in the substituents on the imidazole rings can also enhance the inhibition efficiency.

The separation of racemates remains a great challenge as they are enantiomers with similar chemical structures and physicochemical properties in achiral environments. Recently, graphene oxide (GO) based membranes modified with various chiral selectors had been proved to allow for both high permeation flux and enantioselectivity. Herein, mono(6-amino-6-deoxy)-beta-cyclodextrin (β-CD) was selected to serve as chiral selector in GO-based membranes for separating racemates, since it potentially forms specific inclusion complexes with guests. Results show that β-CD displays a much stronger enantioselective affinity toward l -enantiomer than d -enantiomer, so that such β-CD modified GO membrane (β-CD-GOM) exhibits a retarded transport mechanism, having exceptional enantioselectivities with the enantiomeric excess value of nearly 100%. Moreover, β-CD-GOMs are 1-2 orders of magnitude higher in flux than traditional enantioseparation membranes. These findings demonstrate that β-CD-GOMs could provide new opportunities for improving enantioseparation performances with both high permeability and high permselectivity and for the large-scale production of various enantiomers.

The primary aim of this investigation was to achieve chiral separations via fabricating graphene oxide (GO) based membranes with high separation performances, derived from incorporating a chiral selector ( L -Glutamic acid) into GO flakes, based on considerations of GO membranes having the inherently high throughput nature. The GO membrane was fabricated via a simple vacuum filtration method, in which L -Glutamic acid not only provided the stacked GO nanosheets with the necessary stability to overcome their inherent dispensability in water environment but also finely tuned spacing of the GO nanosheets and the resulting performance. The corresponding membrane structure together with GO and amino acid modified GO nanosheets was systematically characterized by SEM, TEM, AFM, XPS, XRD, FT-IR and so on. Finally, enantioseparation performances of amino acid modified GO membranes toward 3, 4-Dihydroxy-D, L -phenylalanine were detected. Results show that such membranes exhibit extraordinary chiral resolution properties, which are 1−2 orders of magnitude higher in the flux and greater in selectivity, compared to common chiral separation membranes. Our findings demonstrate that the modified GO membranes might provide another general approach to simultaneously facilitate high-flux and high-selectivity for a host of enantio- and bio-separations.

Two new alkaloids, nigellisoquinomine (1) with a novel pyrrolo-isoquinoline skeleton, and nigellapyrrolidine (2) possessing a rare glycosylated pyrrolidine moiety, together with two known alkaloids, agrocybenine (3) and 4,6,6-trimethyl-3,4-epoxypiperidin-2-one (4), were isolated from the seeds of Nigella glandulifera Freyn. Their structures were identified by extensive NMR and HR-ESIMS analysis. Compound 1 exhibited potent protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with an IC50 value of 3.65 ± 0.08 μM.

Diabetes is a metabolic disease with the characteristic of high blood glucose (hyperglycemia). In our previous study, we found that nigelladines A – C (compounds A – C ), three norditerpenoid alkaloids from the seeds of Nigella glandulifera Freyn (Ranunculaceae) exhibited protein of tyrosine phosphatase 1B (PTP1B) inhibitory activity in vitro . In the present study, we further investigated their anti-diabetes activities in L6 moytubes and illuminated the mechanisms of action of compounds A – C . Several parameters of glucose metabolism such as glucose consumption, glycogen content and hexokinase activity were increased by compounds A – C . The results suggested that compounds A–C improved glucose metabolism through promoting synthesis of glycogen. Expression of PTP1B protein was inhibited by compounds A – C in L6 moytubes. PI3K-dependent Akt phosphorylation was found to be activated by compounds A - C and completely blocked by wortmannin (a PI3K inhibitor). Moreover, the insulin-mediated induction of insulin receptor substrate-1 (IRS-1) and glycogen synthase kinase-3β (GSK-3β) were also suppressed by wortmannin. Western blot results indicated that compounds A – C -induced IRS-1/Akt activation was likely a consequence of PTP1B inhibition. Compounds A – C promoted glycogen synthesis through Akt-mediated GSK3 phosphorylation. Therefore, activation of PI3 K/Akt insulin signaling pathway and suppression of PTP1B is the molecular mechanism that contributes to the anti-diabetic effect of compounds A–C in cellular models. The three alkaloids potentially serve as lead compounds for the development of antidiabetic drugs.

Recently, graphene oxide (GO)-based membranes have been demonstrated to be a potential candidate for gas purification and liquid separation techniques owing to their large surface area, tunable interactive sites, and adjustable interlayer spacing. Notably, GO-based membranes functionalized with chiral selectors have been demonstrated to possess high enantiomer permeability and impressive permeation selectivity toward enantiomeric target guests. However, the influence of the GO sheet size on the separation performance remains unclear. Here, we investigated the effect of the lateral size on the enantioseparation performances by modifying a chiral selector onto GO flakes with different sizes, considering that GO membranes possess an inherently high throughput character. In this work, three GO sheets with mean lateral sizes (~60, 650 and 4100 nm) were prepared, hereafter defined as GO1, GO2, and GO3, respectively. Then, a chemical modification of GO1, GO2 and GO3 with a chiral selector, L -Phenylalanine ( L -Phe), yielded the corresponding L -Phe grafted GO sheets, L -Phe-GO1, L -Phe-GO2 and L -Phe-GO3. Finally, L -Phe-GO1, L -Phe-GO2 and L -Phe-GO3 membranes derived from a simple vacuum filtration method were employed to separate D-/ L -phenylalanine. Results show that the L -Phe-GO3 based membrane allows for a remarkable chiral separation capacity, having a greatest enantioselectivity among three L -Phe-GO membranes with different lateral GO sizes. Our findings illustrate that the sheet size of GOs plays a dominant role in the enantioselectivity of membrane separation.

A mesoporous hypercrosslinked polymer (HCP), derived from a Friedel-Crafts alkylation reaction of 1,4-bis(chloromethyl)benzene and a precursor contained heterocyclic ionic liquids, was synthesized, having a high specific surface area with abundant mesopore and specific porosity. In order to reduce 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), a new bismuth nanoparticle/HCP composite (Bi/HCP) as a catalyst was prepared, where the HCP was used as a catalyst carrier. Herein, the HCP was firstly impregnated into a BiCl3 solution to adsorb the Bi3+ ions. After that, these Bi3+ ions adsorbed were then reduced in situ using KBH4, affording the ultimate Bi/HCP composite. In such Bi/HCPs, Bi nanoparticles with a small diameter of 1–3 nm were evenly dispersed. In this work, the Bi/HCPs exhibit an excellent catalytic performance toward the reduction of 4-NP with a low loading, the reaction rate constant k is calculated to be 2.2 min−1, and the catalytic activity did not decrease even after 8 reaction cycles.

CO2 capture and biogas stream purification are of significance to minimize their effect on the global climate change. Usually, flexible metal-organic frameworks (MOFs) could show responsive adsorption for a specific guest. However, in this work, a flexible microporous organic polymer (MOP), BOP-1, was synthesized via intentionally selecting two functional groups (Cl and NH2 moieties). Results show that BOP-1 has a higher uptake of CO2 under 1 bar, i.e., 3.94 and 1.60 mmol/g at 273 and 298 K, respectively. Especially, at 273 K, BOP-1 shows an abrupt transformation over CO2 adsorption and exhibits a high CO2/CH4 selectivity of 568 at 0.02 bar. Both experimental and theoretical methods reveal that the flexible –CH2–NH– linker within the framework plays a critical role in dominating CO2 binding and contributing the flexibility of host frameworks. Our findings could open a new possibility to tailor the function and flexibility of MOPs and to achieve their specific response to targets for the practical application in adsorption.

The pore size of porous materials is of great importance for controlling chiral separation of enantiomers. However, the roles of the porous dimension in determining the separating performance are still unclear, especially when pores are comparable with or slightly larger than the target enantiomers in size. Here, we detected the effect of the pore dimension on the chiral separation performances using organic-inorganic hybrid materials with the different porous sizes at the nanometric level, which bore a chiral selector and thus can selectively bind one of enantiomers. In this work, mesoporous molecular sieves, i.e., SBA-15, KIT-6 and MCM-41, chemically modified with a chiral selector, N-acyl-protected d-glutamic acid, were used to separate d- and l-phenylalanine, as the chiral probes. The structure of hybrid materials, together with raw materials and intermediates, were systematically characterized by TEM, EA, TGA, XRD, FT-IR, and so on. The influence of porous size on enantioseparation behaviors can be defined by comparing enantioseparation results among SBA-15, KIT-6 and MCM-41 based hybrid materials, since they have different inner diameters. Results show that the MCM-41 based hybrid material with a ˜1.1 nm inner diameter exhibits an extraordinary chiral resolution performance, having a greater enantioselectivity, compared with KIT-6 and SBA-15 based hybrid material with the diameter of ˜4.0 and 7.8 nm. Our findings demonstrate that the pore size plays an important role in the enantioselectivity of porous materials.

A sample pretreatment method using acid-base extraction was established for pH-zone-refining counter-current chromatography (CCC) to increase the yield of the target compound. As the most important step, selection of two-phase solvent system for pH-zone-refining CCC should follow some rules. One of these rules is that when pH of two-phase solvent system is around 2 (for an acidic analyte) or 10 (for a basic analyte), partition coefficient values of K(acid) or K(base) should be much greater than 1. According to this rule, a new pretreatment method was developed that could substantially increase the yield of the target compound in pH-zone-refining CCC. The separation of the crude alkaloids extracted from the seeds of Sophora alopecuroides was selected as an example to show the advantage of this method. Before CCC separation, 20 g of crude sample was extracted 3 times with the selected two-phase solvent system composed of MtBE-CH₃CN-H₂O (2:2:3, v/v), where pH of the upper phase was adjusted with triethylamine to 10. A 10 g amount of the second basic extract thus obtained was subjected to pH-zone-refining CCC separation. As a result, 169 mg of sophoramin and 696 mg of sophoearpin were isolated from the second basic extract, where the yields have been doubled compared with those of the untreated sample (crude sample). Experimental results showed that the present method for pretreating the crude sample could produce substantially higher yields of target compounds in pH-zone-refining CCC.

We have synthesized four atropisomers of the pivalamido phenyl substituted porphyrins, α,α,α,β-PivPP (abbreviation of meso-α,α,α,β-tetra(o-pivalamidophenyl)porphyrin), α,β,α,β-PivPP, α,α,β,β-PivPP and α,α,α,α-PivPP. The latter one is usually called the “picket-fence” substituted porphyrin. The interfacial behaviors of the four compounds have been studied by using Langmuir–Blodgett (LB) technique, Ultraviolet–visible (UV–vis) and Atomic Force Microscopy (AFM). The obtained π–A isotherms show that the Langmuir monolayers of PivPPs are formed at the air/water interface except that of α,α,β,β-PivPP which exhibits a platform at the surface pressure in the range of 11–14 mN/m indicating a monolayer transition. The UV–vis spectra disclose that the red-shift happens in the porphyrin Soret bands of the four atropisomer LB films deposited on quartz slides compared with the corresponding absorption bands in the diluted chloroform solution, which results from the strong π–π interaction between porphyrin rings. Except for α,α,β,β-PivPP, AFM images also suggest that the LB films formed by atropisomers of the substituted porphyrin are homogeneous monolayer. Generally, film-forming molecules pack more tightly during compressing the mononlayers, which is consistent with the UV–vis spectra results that the absorption intensities of LB films enhance and the Soret band varies with the increase of surface pressure. On the other hand, AFM morphologies of α,α,β,β-PivPP at higher surface pressure reveal that bilayers are formed, which coincides with the presence of a platform in the π–A isotherm.

Surface properties of the insoluble cationic bis-(quaternary ammonium halide) surfactants (Gemini) with polymethylene spacer at the air/water interface were investigated. The monolayers were transferred onto mica by the Langmuir–Blodgett (LB) technique and the corresponding LB films were characterized by the atomic force microscopy (AFM) and the contact angle of water. For the Gemini surfactants with the different spacer length, it was found that the surface pressure-molecular area isotherms resemble to each other. The limiting area increases rapidly and almost linearly with the increase of spacer length for the short spacers, but reaches a maximum at s = 10 and decreases slightly at s > 10. The AFM images show that the surface micelles and the multilayer aggregates gradually appear with the increase of surface pressure. No matter what the surface pressures are, the main structure of the monolayer almost keeps the same, which suggested that the major molecules lie nearly flat on the water surface, while the increase of surface pressure forces the minor alkyl chains to turn only partly or completely vertical to the water surface and even to overturn. This is the cause that the contact angle of water on LB film increases slightly with the surface pressure.

Two kinds of Gemini surfactant monolayer, which showed different hydrophobic property, were selected as adsorption substrates for collagen. The topographic images of collagen were investigated by using an atomic force microscopy (AFM). Their auto-organized nano-structures were influenced by the property of substrate and the process of sample preparation, such as concentration of collagen solution, adsorption time and drying condition. Network-like structures formed on the both Gemini monolayers. With increasing concentration of collagen solution and adsorption time, the density of the network-like structure increased and their strands became wider and the mesh sizes decreased apparently. Contrary to the reference, the network-like structures of collagen also formed on the less hydrophobic Gemini surfactant monolayer even after very short adsorption time, which was considered to result from the more hydrophobic patch on it.