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Methane dehydroaromatization (MDA) on Mo/ZSM-5 zeolite catalyst provides a promising route for the direct transformation of natural gas into high-valued chemicals. Understanding the nature of active sites on Mo/ZSM-5 represents one of the challenges to be resolved for technical application of this process. Herein, by using (1)H{(95)Mo} double-resonance solid-state NMR spectroscopy, we identify proximate dual active sites on Mo/ZSM-5 catalyst by direct observation of internuclear spatial interaction between Brønsted acid site and Mo species in zeolite channels. The acidic proton-Mo spatial interaction is correlated with methane conversion and aromatics formation in the MDA process, which is demonstrated to be an important factor in determining the catalyst activity and lifetime. The evolution of olefins and aromatics in Mo/ZSM-5 channels is monitored by detecting their host-guest interactions with both active Mo sites and Brønsted acid sites via (1)H{(95)Mo} double-resonance and two-dimensional (1)H-(1)H correlation NMR spectroscopy, which reveals the intermediate role of olefins in hydrocarbon pool process during the MDA reaction.

The harpin protein Hpa1 has various beneficial effects in plants, such as promoting plant growth and inducing pathogen resistance. Our previous study found that Hpa1 could significantly alleviate the mosaic symptoms of tobacco mosaic virus (TMV) in Pinellia ternata, indicating that Hpa1 can effectively stimulate resistance. Here, the potential mechanism of disease resistance and field applicability of Hpa1 against TMV in P. ternata were further investigated. The results showed that 15 µg ml−1 Hpa1 had stronger antiviral activity than the control, and its protective effect was better than its curative effect. Furthermore, Hpa1 could significantly induce an increase in defense-related enzyme activity, including polyphenol oxidase, peroxidase, catalase, and superoxide dismutase, as well as increase the expression of disease resistance-related genes (PR1, PR3, PR5, and PDF1.2). Concurrently, Hpa1 significantly increased the content of some disease resistance-related substances, including hydrogen peroxide, phenolics, and callose, whereas the content of malondialdehyde was reduced. In addition, field application analysis demonstrated that Hpa1 could effectively elicit a defense response against TMV in P. ternata. Our findings propose a mechanism by which Hpa1 can prevent TMV infection in Pinellia by inducing systemic resistance, thereby providing an environmentally friendly approach for the use of Hpa1 in large-scale applications to improve TMV resistance in Pinellia.

Liver cancer is one of the most common malignancies worldwide and poses a serious threat to human health. The most important treatment method, liver cancer chemotherapy, is limited due to its high toxicity and poor specificity. Targeted drug delivery systems have emerged as novel therapeutic strategies that deliver precise, substantial drug doses to target sites via targeting vectors and enhance the therapeutic efficacy. In the present study, glycyrrhetinic acid-modified hyaluronic acid (GA-HA) was used as a carrier for the model drug docetaxel (DTX) to prepare DTX-loaded GA-HA nanoparticles (DTX/GA-HA-NPs). The results indicated that the DTX/GA-HA-NPs exhibited high monodispersity (particle dispersity index, 0.209±0.116) and desirable particle size (208.73±5.0 nm) and zeta potential (-27.83±3.14 mV). The drug loading capacity and encapsulation efficiency of the NPs were 12.59±0.68 and 85.38±4.62%, respectively. Furthermore, it was determined that FITC-GA-HA was taken up by cells and distributed in the cytoplasm. DTX and DTX/GA-HA (just the DTX delivered by the nanoparticle) aggregated and altered the structure of cellular microtubules. Compared with DTX alone, DTX/GA-HA-NPs had a stronger inhibitory effect on HepG2 cell proliferation and promoted apoptosis of HepG2 cells. All experimental results indicated that DTX/GA-HA-NPs were successfully prepared and had liver-targeting and antitumor activities in vitro, which provided a foundation for future in vivo studies of the antitumor effects of DTX/GA-HA-NPs.

Monodispersed hairy nanocomposites with typical 2 nm (isophthalic acid)24 Cu24 metal-organic polyhedra (MOP) as a core protected by 24 polymer chains with controlled narrow molecular weight distribution has been probed by imaging and scattering studies for the heterogeneity of polymers in the nanocomposites and the confinement effect the MOPs imposing on anchored polymers. Typical confined-extending surrounded by one entanglement area is proposed to describe the physical states of the polymer chains. This model dictates the counterintuitive thermal and rheological properties and prohibited solvent exchange properties of the nanocomposites, whilst those polymer chain states are tunable and deterministic based on their component inputs. From the relationship between the structure and behavior of the MOP nanocomposites, a MOP-composited thermoplastic elastomer was obtained, providing practical solutions to improve mechanical/rheological performances and processabilities of inorganic MOPs.

We carried out a large set of tests to establish a correlation between the molecular (network) structure (influenced by molecular weight, molecular weight distribution, and melt predeformation) and mechanical responses of several glassy polymers to uniaxial compression at different temperatures and different compression speeds. The experimental results show that to have ductile responses there must be an adequate chain network, afforded by the interchain uncrossability among sufficiently long chains. Specifically, polystyrene (PS) and poly(methyl methacrylate) of sufficiently low molar mass do not have chain network and are found to be very brittle. Binary PS mixtures are brittle at room temperature when the volume fraction of the high‐molecular‐weight component is sufficiently low (e.g., at and below 27.5%). Moreover, sufficiently melt‐stretched PS mixtures show brittle fracture when compressed along the same direction, along which melt stretching was made. All the experimental findings confirm that a robust chain network is also a prerequisite for yielding and ductile cold compression of polymer glasses, as is for extension. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 758–770

Hepatocellular carcinoma (HCC), a common malignancy in China and globally, is primarily treated through surgical resection and liver transplantation, with chemotherapy as a significant synergistic option. Adenine (Ade), a nucleobase, exhibits antitumor effects by blocking human hepatic carcinoma cells in S phase and inhibiting tumor cell proliferation. However, its use is limited owing to its low solubility, poor targeting ability, and nephrotoxicity. Therefore, liver-targeting drug delivery systems have attracted considerable attention for the treatment of HCC. In this study, we explored the liver-targeting efficacy and antitumor effect of adenine-loaded glycyrrhetinic acid-modified hyaluronic acid (Ade/GA-HA) nanoparticles in vitro and in vivo. The GA-HA nanoparticles possessed obvious targeting specificity toward liver cancer cells, which was mainly achieved by the specific binding of the GA ligand to the GA receptor that was highly expressed on the liver cell membrane. In vitro and in vivo results showed that Ade/GA-HA nanoparticles could inhibit liver cancer cell proliferation and migration, promote apoptosis, and significantly inhibit the growth of tumor tissues. Altogether, this study is the first to successfully demonstrate that the targeting activity and antitumor effect of Ade against HCC are enhanced by using GA-HA nanoparticles in vitro and in vivo.

The morphologies of ABC miktoarm star terpolymer consisting of polystyrene (PS), polyisoprene (PI), and poly(2-vinylpyridine) (P2VP) were studied by combining small-angle neutron and X-ray scattering (SANS and SAXS) and transmission electron microscopy. We find that this system displays a rich morphological behavior including an alternate lamellar (ALT.LAM), cylinder in undulated lamellar (CYLULAM), and 3-lamellar (LAM-3) phase. While the SAXS data alone were insufficient to conclusively differentiate between possible phases, we show that the use of selective deuteration and SANS is essential to unambiguously identify the morphology. In particular, the primary peak in SANS for the miktoarm polymer containing deuterated PS was found to be lower than the next two higher order peaks. Such an unusual scattering pattern for a lamellar morphology was verified by self-consistent field theory calculations when the relative strength of the interaction between PI–P2VP over PS–PI is equal to or greater than 2 (χIV/χ...

Advanced glycation end products (AGEs) are complex and heterogeneous compounds, which play an important role in diabetic-related vascular complications, especially in atherosclerosis. In this study, the effects of ferulic acid (FA) on glucose-related protein glycation were investigated in vitro by various spectroscopic techniques and molecular docking methods. In order to study the protective effects of FA on AGEs-induced HUVEC cells damage, the mRNA expression of Caspase-1, NLRP3, CRP, ICAM-1, VCAM-1, IL-18 and IL-1β were detected. Moreover, NF-κB and p38 MAPK signaling pathways were analyzed. These results manifested that FA could effectively inhibit the AGEs formation, decrease the AGEs-induced mRNA expression of Caspase-1, NLRP3, CRP, ICAM-1, VCAM-1, IL-18 and IL-1β, and reduce intracellular ROS. FA could mitigate the AGEs-induced inflammatory response in HUVEC cells by suppressing the activation of NF-κB and p38 MAPK signaling pathways. These results suggested that FA might prevent and mitigate the development of atherosclerosis in diabetic patients.

Highly efficient proton conductors, polyoxometalate-poly(ethylene glycol) (POM-PEG) hybrid nanocomposites, have been synthesized by encapsulating a single PEG chain inside the 1D nanochannel defined by the frameworks of POMs. By employing two types of neutron scattering techniques complemented by thermal analysis, we prove that in a nanochannel a single PEG chain stays as a distorted helix. More importantly, we reveal that the PEG segments perform a localized longitudinal random walk and quantitatively show the strong correlation between the local motion of PEG and the macroscopic proton conduction of the material. On the basis of these spatial-temporal characteristics, a microscopic picture for the proton conduction process of POM-PEG hybrid materials is proposed.

Broadband dielectric spectroscopy (BDS) is used to probe the chain and segmental dynamics of A2B2 and AB2 miktoarm star copolymers based on polystyrene (PS, A block) and polyisoprene (PI, B block) that display lamellar morphologies as determined using small-angle X-ray scattering (SAXS). While no changes in the distribution of PI segmental relaxation times are observed with variation of the molecular architecture, an unexpected increase in the normalized PI chain relaxation intensity is realized for AB2 miktoarm star copolymers as well as a change in the distribution of chain relaxation rates as compared to A2B2 and AB diblock copolymer systems. This result is attributed to asymmetry in the molecular architecture near the junction point, which affects the osmotic constraint of the tethered PI chains within the interfacial region of the lamellae. The results highlight the importance of macromolecular design on fundamental chain dynamics in phase-separated thermoplastic elastomers.

The heterogeneous hydrogenation of propene over supported Pd–Au bimetallic nanoparticles was investigated using NMR and the parahydrogen-induced polarization (PHIP) technique. The composition and structure of Pd–Au/TiO2 catalysts were correlated to both catalytic activity and pairwise hydrogen addition. Sol-immobilization, impregnation, and deposition–precipitation methods were used for preparation of the Pd–Au bimetallic catalysts. A strong signal enhancement was observed on the bimetallic catalyst prepared through the sol-immobilization method, up to 24-fold higher than that with the other two methods. The polyvinyl alcohol (PVA) stabilizer bound to the metal surface was responsible for the enhanced PHIP effect. The removal of the PVA ligands by water washing and calcination treatments shows a significant effect on the hydrogen pairwise addition. Increasing the Au content in the bimetallic alloy led to a promotion of the pairwise selectivity due to the ensemble effect. The pairwise selectivity could be ...

A general strategy has been developed here to co-assemble polyoxometalates (POMs) and polymers into core–shell hybrid nanoparticles via hydrogen bonding interaction. Due to the hydrogen bonds between the pyridine groups of poly(4-vinyl pyridine) (P4VP) and the hydrogen bonding donor groups on the POM surface, P4VP is stabilized by the POMs and dispersed as discrete hybrid core–shell nanoparticles in aqueous solution. For these thermodynamically stable nanoparticles, the P4VP cores are covered with hexagonal close-packed POMs. The size of the core–shell particles is controlled by the electrostatic repulsive interaction among the POMs. The introduction of extra salts screens the repulsive force among the POMs, thus increasing the size of the core–shell structures.

All-acrylic multigraft copolymers, poly(butyl acrylate)-g-poly(methyl methacrylate), synthesized using a facile grafting-through methodology, exhibit elongation at break (>1700%) and strain recovery behavior far exceeding those of any commercial acrylic (∼500%) and styrenic (∼1000%) triblock copolymers to date. One-batch anionic polymerization of methyl methacrylate (MMA) using the sec-butyl lithium/N-isopropyl-4-vinylbenzylamine (sec-BuLi/PVBA) initiation system gives PMMA macromonomers with quantitative yield, short reaction time, and using simple synthetic procedures. These new all-acrylic superelastomers and the simple synthetic approach greatly expand the range of potential applications of all-acrylic thermoplastic elastomers (TPEs).

A novel class of ortho, para-alternating linked polyarenes is synthesized via catalyst-transfer Suzuki coupling polymerization with Pd2(dba)3/t-Bu3P/p-BrC6H4COPh as initiator. Through a series of kinetic studies and MALDI-TOF analysis, the polymerization is shown to proceed in a chain-growth manner. The optical and thermal properties for the ortho, para-alternating linked polyarenes exhibit unusual molecular weight dependence. Thus, the polymer with lower molecular weight (Mn = 6300 g mol−1) emits green fluorescence whereas the one with higher molecular weight (Mn = 13 800 g mol−1) emits blue fluorescence under UV (λ = 360 nm) irradiation. Furthermore, an all-conjugated block copolymer containing a polyfluorene block and the ortho, para-alternating linked block is also successfully prepared, in a one-pot procedure. These results can provide a pathway to obtain polyarenes with precisely controlled structures, hence, desirable properties.

The hydrocarbon pool (HP) species in methanol-to-olefins (MTO) reactions over zeolite H-ZSM-5 were investigated by solid-state NMR spectroscopy and GC–MS. The distribution and reactivity of retained HP species such as carbocations and methylbenzenes (MBs) were found to evolve with reaction time and their positions in the catalyst bed. The underlying mechanism of the typical S-shaped methanol conversion curve was revealed, in which the dominating reaction route was found to be dependent on the formation and reactivity of different HP species that were varied at different reaction time. During the induction period, cyclopentenyl cations served as the precursor to MBs and exhibited higher reactivity than the latter. The reaction was accelerated by the accumulation of alkenes and further enhanced by consequent involvement of the cyclopentenyl cations and aromatics, which eventually led to a steady state reaction. The interconversions of the reaction cycles based on alkenes, cyclopentenyl cations, and MBs were proposed for the formation of light olefins. The co-catalysis of HP species in the MTO reactions showed that the cyclopentenyl cations and alkenes favored propene formation, while the light MBs such as xylene and triMB facilitated ethene formation. Within the catalyst bed, both cyclopentenyl cations and MBs were dominantly formed in the upper catalyst layers. The experiments indicated that both cyclopentenyl cations and alkenes maintained high reactivity throughout the catalytic bed, while MBs exhibited high reactivity only in the upper catalyst position.

Poly(1-adamantyl acrylate) (PAdA) exhibits much higher glass transition and degradation temperatures than other polyacrylates. However, the quantitative evaluation of the stiffness of this polymer chain has not been reported previously. In this study, the dilute solution properties and conformational characteristics of PAdA were evaluated using viscometry and scattering techniques. The unperturbed dimensions of this polymer were evaluated using the Burchard–Stockmayer–Fixman extrapolation and the touched-bead wormlike chain model. The PAdA chain has a comparable persistence length, diameter per bead and characteristic ratio to poly(methyl methacrylate) and polystyrene. All these results indicate that PAdA is less flexible than common polyacrylates. In addition, the second virial coefficients (A2) of PAdA in different solvents obtained by static light scattering were compared. Among the solvents investigated, tetrahydrofuran is a moderate solvent. Radius of gyration of a polymer sample in the various solvents ranged from 16.8 to 30.3 nm. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017

Single-ion conducting polymer electrolytes (SCPE) are attractive candidates for high-performance energy storage devices. A star-shaped single lithium-ion conducting polymer electrolyte was synthesized by combining the “grafting to” and “grafting from” strategy utilizing a polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the core. Carboxylic acid terminated polyethylene oxide (PEO) and Reversible Addition Fragmentation Chain Transfer Agent (RAFT-CTA) were attached to the POSS nanoparticle to form a POSS-cored macro RAFT CTA (PMR-CTA). The PMR-CTA was used to mediate the polymerization of potassium (styrene-4-sulfonyltrifluoromethyl-sulfonyl)imide (STF-K+) and subsequent counter ion exchange resulted in a star-shaped single lithium-ion conducting copolymer (SSCP-Li+). The grafting ratio of poly(STF-Li+) and PEO per POSS nanoparticle can be tuned by modifying the feed ratio of the two polymer components. The synthesized star-shaped SCPE-Li+ are characterized by 1H NMR, FT-IR, UV-Vis, DLS, GPC and DSC, and their ionic conductivity is studied by broadband dielectric spectroscopy. The obtained results are compared to a conventional linear homopolymer poly(STF-Li+) and block copolymer PEO-b-poly(STF-Li+), and reveal a significant “decoupling” of ion conductivity from segmental dynamics for all of the studied SCPE-Li+. Blending extra PEOs with SCPE-Li+ was also performed to improve the ionic conductivity.

In this study, four fusion proteins were designed, in which the N-terminal cellulose-binding module as the affinity tag was immobilized on the regenerated amorphous cellulose (RAC), and the release of the C-terminal colored proteins was detected easily and rapidly after on-resin cleavage using the free tobacco etch virus protease (TEVp) variant, or the immobilized cognate protease with a binding capacity of up to 220 mg protein per gram of RAC. The enhanced stability and repetitive use of the immobilized TEVp compensated slight loss of the catalytic efficiency toward the soluble protein substrate. On-resin cleavage and purity of the released target proteins are related to the context of the fusion tag, the incorporated linker composition, and the colored protein. Owing to low cost and high binding capacity of the RAC, the TEVp immobilized on the resin is an ideal alternative for removing fusion tag. The colored proteins are easily monitored in the on-resin process of fusion proteins, and rapid separation from RAC.

All acrylic-based thermoplastic elastomers (TPEs) offer potential alternatives to the widely-used styrenic TPEs. However, the high entanglement molecular weight (Me) of polyacrylates, as compared to polydienes, leads to “disappointing” mechanical performance as compared to styrenic TPEs. In this study, triblock copolymers composed of alkyl acrylates with different pendant groups and different glass transition temperatures (Tgs), i.e. 1-adamatyl acrylate (AdA) and tetrahydrofurfuryl acrylate (THFA), were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. Thermal characterization of the resulting polymers was performed using differential scanning calorimetry (DSC), and the Tgs of both segments were observed for the block copolymers. This indication of microphase separation behavior was further demonstrated using atomic-force microscopy (AFM) and small angle X-ray scattering (SAXS). Dynamic mechanical analysis (DMA) showed that the softening temperature of the PAdA domains is 123 °C, which is higher than that of both styrenic TPEs and commercial acrylic based TPEs with poly(methyl methacrylate) (PMMA) hard block. The resulting triblock copolymers also exhibited stress–strain behavior superior to that of conventional all acrylic-based TPEs composed of PMMA and poly(n-butyl acrylate) (PBA) made by controlled radical processes, while the tensile strength was lower than for products made by living anionic polymerization.

The carbonylation reaction of ethane with CO to produce carboxylic acid was studied over zinc-modified ZSM-5 zeolite (denoted as Zn/ZSM-5) using in situ solid-state NMR spectroscopy. 13C-isotope-labeled reactants were alternatively used to monitor the co-reaction at temperatures of 298–623 K. The NMR experimental results demonstrated that surface zinc-ethyl and methoxy species were formed and identified as key intermediates in the reaction. The reactivity of these intermediates was further explored under both oxidizing and reducing conditions by adding O2 and H2 into the reaction system. It was found that ethane was initially activated into zinc–ethyl species that show reactivity similar to that of organometallic compounds such as diethyl zinc. The interaction of zinc–ethyl species with CO2 resulting from the oxidation of CO produces propanoic acid. Side products such as aromatics were formed by dehydrogenation of zinc–ethyl species via the formed ethene intermediates. We also found that hydrogenolysis of ethane occurred and gave rise to byproduct methane, which led to the formation of acetic acid by carboxylation with CO2. Additionally, CO was converted into surface methoxy species, which could react with CO to produce acetic acid via a Koch-type carbonylation reaction.

Fast deformation of entangled melts is known to cause chain stretching due to affinelike straining of the entanglement network. Since the chain deformation may also result in perturbations of covalent bond angles and bond length, there are always possible enthalpic effects. In this study, we first subject polystyrene and PMMA of different molecular weights to either uniaxial melt extension or planar extension and subsequently impose rapid thermal quenching to preserve the chain deformation. Then, such pre-melt-deformed samples are annealed at various temperatures below the glass transition temperature Tg. During annealing, these samples can undergo appreciable contraction on a time scale much shorter than the alpha relaxation time. Significant retractive stress is observed when such contracting samples are held fixed during the annealing. The stress level can be nearly as high as the Cauchy stress produced during melt stretching. These observations not only allowed us to investigate glassy chain dynamics as well as the molecular nature of mechanical stress but may also suggest that pre-melt-stretched polymers can cause segmental mobilization in the glassy state. The available evidence indicates that the retractive stress is enthalpic in origin, associated with the conformational distortion at the bond level produced by melt stretching.

The advanced glycation end products (AGEs) are the compounds produced by non-enzymatic glycation reaction of proteins and sugars, which can induce the generation of free radicals and the expression of inflammatory factors, thereby playing an important role in vascular dysfunction in diabetes. To investigate the effects of caffeic acid (CA) on glycation formed by glucose and protein, various spectroscopic techniques and molecular docking methods were carried out. Furthermore, the protective effects of CA on human umbilical vein endothelial cells (HUVECs) damaged by AGEs were detected. The results indicated that CA inhibited AGEs formation in vitro, decreased the expression of IL-1β, IL-18, ICAM-1, VCAM-1, NLRP3, Caspase-1 and CRP (C-reactive protein) and reduced the ROS in HUVECs exposed to AGEs. Our findings suggested that the supplementation with dietary CA could prevent and delay the AGEs-induced vascular dysfunction in diabetes.

The unique properties of ionic liquids (ILs) have made them promising candidates for electrochemical applications. Polymerization of the corresponding ILs results in a new class of materials called polymerized ionic liquids (PolyILs). Though PolyILs offer the possibility to combine the high conductivity of ILs and the high mechanical strength of polymers, their conductivities are typically much lower than that of the corresponding small molecule ILs. In the present work, seven PolyILs were synthesized having degrees of polymerization ranging from 1 to 333, corresponding to molecular weights (MW) from 482 to 160 400 g/mol. Depolarized dynamic light scattering, broadband dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to systematically study the influence of MW on the mechanism of ionic transport and segmental dynamics in these materials. The modified Walden plot analysis reveals that the ion conductivity transforms from being closely coupled with structural relaxation...

Terpenoids are one of the main components of plant aromas. In the present study we investigated these compounds in Osmanthus fragrans Lour., which is a fragrant plant widely used for the production of essential oils. Quantitative real-time PCR (qRT-PCR) results of enzymes associated with the 2-C-methylerythritol-4-phosphate pathway confirmed that the TPS is a key enzyme for terpenoid synthesis in O. fragrans. In a series of experiments, we identified the TPS candidate genes in O. fragrans and revealed the underlying catalytic activity and subcellular localisation of the encoded proteins. Because there is no available O. fragrans reference genome, we sequenced and analysed its transcriptome and identified two putative TPS genes, OfTPS1 and OfTPS2. According to qRT-PCR analysis, both genes were most highly expressed at the full-bloom stage, suggesting that OfTPS1 and OfTPS2 contribute to O. fragrans terpenoid synthesis. To verify this hypothesis, we constructed prokaryotic expression vectors to obtain protein. In order to study the function of OfTPS1 and OfTPS2 in the synthesis of monoterpenes, the obtained proteins were reacted with geranyl pyrophosphate. As a result, two kinds of monoterpenes, (E)-β-ocimene and linalool, were detected from reaction products, respectively. In conclusion, OfTPS1 and OfTPS2 are both monoterpene synthases.

In this study, we analyzed and compared the properties of yeast Ulp1 protease in active inclusion bodies (IBs) as special protein immobilizate, and the soluble Ulp1 via oriented immobilization. Fusion of the N-terminal self-assembling peptide GFIL8 to the Ulp1 increased production of active IBs in Escherichia coli. Attachment of the N-terminal cellulose-binding module facilitated the constructed protein immobilized on the regenerated amorphous cellulose (RAC) with a binding capacity up to about 235 mg protein per gram of RAC. Compared with the immobilized soluble construct, the insoluble Ulp1 showed higher resistance to limited proteolysis with trypsin digestion, lower leaky amount at different storage temperatures, but more rapid decrease in cleavage activity after stored at 4°C for 8 days. The immobilized soluble Ulp1 maintained about 42% initial cleavage activity with repetitive use successively, whereas the aggregated Ulp1 lost its cleavage capacity after cleaving the protein substrate once. Crosslinking of IBs mediated by glutaraldehyde inactivated the Ulp1. Freshly prepared and used IBs showed similar resistance to protease-K digestion, and comparable binding capacity of Congo red and thioflavin T. Taken together, due to different advantages, the Ulp1 constructs as carrier-free and carrier-dependent immobilizates are used under different conditions.

The formation and reactivity of a methylbenzenes (MBs) hydrocarbon pool in the induction period of the methanol-to-olefins (MTO) reaction over zeolite H-ZSM-5 was investigated and the mechanistic link of MBs to ethene and propene was revealed. Time evolution analysis of the formed MBs and C-12/C-13 methanol-switching experiments indicate that in the induction period bulkier compounds such as tetraMB and pentaMB have higher reactivity than their lighter counterparts such as p/m-diMB and triMB. By correlating the distribution of MBs trapped on H-ZSM-5 with ethene and propene, we found that tetraMB and pentaMB favor the formation of propene, while p/m-diMB and triMB mainly contribute to the formation of ethene. On the basis of this relationship, the olefin (ethene and propene) selectivity can be controlled by regulating the distribution of trapped MBs by varying the silicon-to-aluminum ratio of ZSM-5, reaction temperature, and space velocity. The reactivity of MBs and the correlation of MBs with olefins were also verified under steady-state conditions. By observation of key cyclopentenyl and pentamethylbenzenium cation intermediates using in situ solid-state NMR spectroscopy, a paring mechanism was proposed to link MBs with ethene and propene. P/M-diMB and triMB produce ethylcyclopentenyl cations followed by splitting off of ethene, while tetraMB and pentaMB generate propyl-attached intermediates, which eventually produce propene. This work provides new insight into the MBs hydrocarbon pool in MTO chemistry. (C) 2015 Elsevier Inc. All rights reserved.

We present the synthesis of poly(n-butyl acrylate)-g-poly(methyl methacrylate) (PnBA-g-PMMA) multigraft copolymers via a grafting-through (macromonomer) approach. The synthesis was performed using two controlled polymerization techniques. The PMMA macromonomer was obtained by high-vacuum anionic polymerization followed by the copolymerization of n-butyl acrylate and PMMA macromonomer using reversible addition–fragmentation chain transfer (RAFT) polymerization to yield the desired all-acrylic multigraft structures. The PnBA-g-PMMA multigraft structures exhibit randomly spaced branch points with various PMMA contents, ranging from 15 to 40 vol %, allowing an investigation into how physical properties vary with differences in the number of branch points and molecular weight of grafted side chains. The determination of molecular weight and polydispersity indices of both the PMMA macromonomer and the graft copolymers was carried out using size exclusion chromatography with triple detection, and the structural ...

Polystyrene of different molecular weights and their binary mixtures are studied in terms of their various mechanical responses to uniaxial compression at different temperatures. PS of Mw = 25 kg/mol is completely brittle until it is above its glass transition temperature Tg. In contrast, upon incorporation of a high molecular weight component, PS mixtures turn from barely ductile a few degrees below its Tg to ductile over 40° below Tg. In the upper limit, a PS of Mw = 319 kg/mol yields and undergoes plastic flow, even at T = −70 °C. The observed dependence of mechanical responses on molecular weight and molecular weight distribution can be adequately rationalized by the idea that yielding and plastic compression are caused by chain networking.

The methanol to olefins conversion over zeolite catalysts is a commercialized process to produce light olefins like ethene and propene but its mechanism is not well understood. We herein investigated the formation of ethene in the methanol to olefins reaction over the H-ZSM-5 zeolite. Three types of ethylcyclopentenyl carbocations, that is, the 1-methyl-3-ethylcyclopentenyl, the 1,4-dimethyl-3-ethylcyclopentenyl, and the 1,5-dimethyl-3-ethylcyclopentenyl cation were unambiguously identified under working conditions by both solid-state and liquid-state NMR spectroscopy as well as GC-MS analysis. These carbocations were found to be well correlated to ethene and lower methylbenzenes (xylene and trimethylbenzene). An aromatics-based paring route provides rationale for the transformation of lower methylbenzenes to ethene through ethylcyclopentenyl cations as the key hydrocarbon-pool intermediates.

In this work, high molecular weight “comb-shaped” graft copolymers, poly(isoprene-g-styrene), with polyisoprene as the backbone and polystyrene as side chains, were synthesized via free radical emulsion polymerization by copolymerization of isoprene with a polystyrene macromonomer synthesized using anionic polymerization. A small amount of toluene was used in order to successfully disperse the macromonomer. Both a redox and thermal initiation system were used in the emulsion polymerization, and the latex particle size and distribution were investigated by dynamic light scattering. The structural characteristics of the macromonomer and comb graft copolymers were investigated through use of size exclusion chromatography, spectroscopy, microscopy, thermal analysis, and rheology. While the macromonomer was successfully copolymerized to obtain the desired multigraft copolymers, small amounts of unreacted macromonomer remained in the products, reflecting its reduced reactivity due to steric effects. Nevertheles...

Multigraft copolymer superelastomers consisting of a poly(n-butyl acrylate) backbone and polystyrene side chains were synthesized and the viscoelastic properties of the non-sulfonated and sulfonated final materials were investigated using extensional rheology (SER3). The non-linear viscoelastic experiments revealed significantly increased true stresses (up to 10 times higher) after sulfonating only 2–3% of the copolymer while the materials maintained high elongation (

Comb and centipede multigraft copolymers, poly(n-butyl acrylate)-g-polystyrene (PnBA-g-PS) with PnBA backbones and PS side chains, were synthesized via high-vacuum anionic polymerization and miniemulsion polymerization. Single-tailed and double-tailed PS macromonomers were synthesized by anionic polymerization and Steglich esterification. Subsequently, the copolymerization of each macromonomer and nBA was carried out in miniemulsion, and multigraft copolymers were obtained. The latex particles of multigraft copolymers were characterized using dynamic light scattering. The molecular weights of macromonomers and multigraft copolymers were analyzed by size exclusion chromatography. Moreover, the molecular weights and structures of macromonomers were investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 1H nuclear magnetic resonance spectroscopy. The weight contents of PS in comb and centipede multigraft copolymers were calculated by 1H nuclear magnetic resonance spe...

The development of multianalyte immunoassays with an emphasis on food safety has attracted increasing interest, due to its high target throughput, short detection time, reduced sample consumption, and low overall cost. In this study, a superior polyclonal antibody (pAb) against sulfonamides (SAs) was raised by using a bioconjugate of bovine serum albumin with a rationally designed hapten 4-[(4-aminophenyl) sulfonyl-amino]-2-methoxybenzoic acid (SA10-X). The results showed that the pAb could recognize 19 SAs with 50% inhibition (IC50) below 100 &micro, g L&minus, 1 and a recognition profile for SAs containing, either a five-atom ring or a six-atom ring, with highly uniform affinity. A three-dimensional quantitative structure-activity relationship analysis indicated that the electrostatic features of SAs play a considerably important role, during recognition with pAb than stereochemical effects. Skimmed milk samples were directly diluted five times before analysis. After optimization, the limit of detection for sulfamonomethoxine, sulfamethoxazole, sulfaquinoxaline, sulfadimethoxine, and sulfamethazine were 1.00, 1.25, 2.95, 3.35, and 6.10 &micro, 1, respectively. The average recoveries for these 5 SAs were 72.0&ndash, 107.5% with coefficients of variation less than 14.1%. The established method, based on pAb, with broad specificity and uniform affinity, offered a simple, sensitive, and high-throughput screening tool for the detection of multi-SAs in milk samples.

The disruption of the delicate balance between the generation of reactive oxygen species (ROS) and antioxidant scavenging systems can lead to many health problems. Polysaccharides extracted from fungi fruit body and myceliums have several potential health benefits. In this study, the antioxidant capacity and cell protective effects of a polysaccharide isolated from Lentinus edodes mycelia (LMP) were investigated. The antioxidant properties of LMP were screened using radical scavenging (1, 1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, and superoxide anion), reducing power and inhibition of lipid peroxidation assays. Intracellular reactive oxygen species (ROS), in response to H 2 O 2 , was determined by the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. Rat insulinoma (INS-1) cells apoptosis was detected using flow cytometry analysis. The results showed that LMP exhibited significantly strong radical scavenging activity. At the concentration of 2.0 mg mL -1 , DPPH radical, hydroxyl radical, and superoxide anion radical scavenging rates are 80.32 ± 2.58%, 92.56 ± 3.11% and 93.73 ± 2.82%, respectively. The reducing power and inhibition of lipid peroxidation activity of LMP were as strong as the positive control. LMP alleviated the intracellular reactive oxygen species level and inhibited islet cell apoptosis significantly. The results open perspectives for studies of LMP in the treatment of diabetes.

Heat stress (HS) damages the global dairy industry by reducing milk yields and quality, harming health, and damaging the reproduction of dairy cows, causing huge economic losses each year. However, an understanding of the physiological mechanism of HS lactating dairy cows remains elusive. Here, a metabolomics study using LC-MS and 1H NMR spectroscopy was performed to analyze the metabolomic differences in the milk between HS-free and HS dairy cows, and discover diagnostic biomarkers and changes in the metabolic pathway. A total of 53 discriminating metabolites were significantly up- or down-regulated in the HS group compared with the HS-free group (P

We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene polyisoprene polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (T-g) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 +/- 1.3 MPa and strain at break of 1390 +/- 66% from tensile tests. The stress strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffine tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis that the softening temperature of PBF in FIF was 145 degrees C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. In addition, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.

We report the preparation of water-soluble, surface-enhanced Raman scattering (SERS)-tagged Au nanorod (NR) probes. That was accomplished by direct ligand exchange of the initial stabilizer with a synthesized Raman-active poly(ethylene glycol) (PEG). The SERS-tagged Au NR probes were characterized by transmission electron microscopy, SERS, and UV–Vis spectroscopy. The Au NR probes exhibited optimized SERS signals due to the coupling of the longitudinal surface plasmon resonance of the Au NRs with the excitation wavelength. Furthermore, they were stable in adverse conditions because the outer PEG protecting layer provided steric stability to them. These multifunctional nanoprobes are expected to have wide applications in biological analysis and biomedicine.

A simple, reliable, economical method was developed using HPLC with a diode-array detector for determination of total flavonoids in plasma after introvenous administration of ginkgo biloba extract. The method simultaneously detects quercetin, kaempferol, and isorhamnetin after acid hydrolysis and recalculation. The hydrolysis and extraction conditions were optimized in an orthogonal test. The specificity was tested by comparing the retention time, UV spectra, and peak purity indices with standards. The detection limits were 20 ng/mL for quercetin, 20 ng/mL for kaempferol, and 50 ng/mL for isorhamnetin. The calibration curve ranges were 75–2400, 71–2280, and 70–2240 ng/mL. The pharmacokinetic characteristics of ginkgo biloba flavonoids after venous administration of 50 mg/kg ginkgo biloba extract to rats were analyzed using a two-compartment model. The initial plasma concentration was 171.22 μg/mL. The half-life of flavonoids in the first compartment (distribution) was 0.07 h and at the second compartment (elimination) was 4.51 h, while the AUC(0-∞) was 1711.06 μg·min/mL. The apparent volume of distribution was 0.11 L/kg. The total body clearance is 10.52 mL/(min·kg). The result shows the method is suitable for pharmacokinetic studies.

The fast separation capability of a capillary electrophoresis with electrochemical detection (CE-ED) system was demonstrated by determining five beta-agonists including clenbuterol, metoprolol, ractopamine, isoxsuprine and salbutamol in several real samples. Factors influencing the separation and detection were examined and optimized. Under the optimum conditions, the five beta-agonists could be well separated within 15min at a separation voltage of 14kV in a 100mmoL H(3)BO(3)-Na(2)B(4)O(7) running buffer (pH 9.0). This method was successfully used in the analysis of clenbuterol, metoprolol, ractopamine, isoxsuprine and salbutamol in pig feed, pig urine and pig liver, providing a useful method for monitoring the illegal use of beta-agonists from growth promotion in food-producing animals.

Diethylene glycol (DEG) can be determined in toothpaste via capillary electrophoresis at 16 kV using a fused silica capillary of 75 cm length and of 25 μm diameter along with a copper disc electrode detector operated at + 0.65 V (vs. SCE). DEG, propylene glyco1 and glycerol in a running buffer of pH 9.2 were separated within 17 min. The linear range for DEG is from 840 to to 4.2 μg·mL−1, and the detection limit (at S/N = 3) is 1.6 μg·mL−1 which therefore meets the safety limit. When applied to the analysis of DEG in toothpaste, the recoveries are between 96.9 and 103.0% for spiked samples and thus are quite satisfactory.

A secondary amino group modified MCM-41 (mobile crystalline material number 41) was synthesized and used as a support for the immobilization of a salen oxovanadium complex via a multi-grafting method. The immobilized complex was characterized by UV–Vis spectroscopy, X-ray diffraction (XRD), N2 adsorption and ICP analysis techniques. The immobilized complex was found to be an effective catalyst for oxidation of cyclohexane using H2O2 as an oxidant under mild conditions. A conversion of 45.5% of cyclohexane was obtained with a selectivity of 100% of the cyclohexanone/cyclohexanol mixture when the reaction was run at 60 °C for 12 h in acetonitrile. Decomposition of the complex, which leads to the deactivation of the catalyst, is observed and a decomposition mechanism is discussed.

Capillary-zone electrophoresis with electrochemical detection has been used for the separation and determination of (-)-epicatechin, rutin, hyperin, chlorogenic acid, and quercetin in hawthorn and hawthorn piece. The effects of several important factors, including the running buffer acidity, the separation voltage, and the working electrode potential, were evaluated to acquire the optimum analytical conditions. The working electrode was a 300-μm carbon-disk electrode at a working potential of +0.95 V (vs. SCE). Under the optimum conditions, the analytes can be well separated within 16 min in a 75-cm-long fused-silica capillary. The current response was linear over two orders of magnitude with detection limits (S/N = 3) ranging from 6.00 × 10−8 to 3.75 × 10−7 g/mL for all analytes. The method was successfully used in the analysis of hawthorn and hawthorn piece and the assay results were satisfactory.

A method based on capillary zone electrophoresis with electrochemical detection (CE-ED) has been employed for the separation and determination of epicatechin, scopoletin, quercetin and gallic acid in Toona sinensis (A. Juss) Roem leaves. Seasonal variations of these ingredients in T. sinensis (A. Juss) Roem leaves collected in April, June and August, were discussed. Several important factors including running buffer acidity, separation voltage, working electrode potential and etc., were evaluated to acquire optimum analysis conditions. Under the selected optimum conditions, these analytes could be well separated. Good linear relationship was established between the peak current and the concentration of each analyte over 2–3 orders of magnitude with detection limits (S/N = 3) ranging from 4.00 × 10−8 to 1.73 × 10−7g mL−1. The proposed method has been successfully applied for the evaluation of the seasonal content variation of these four active ingredients in T. sinensis (A. Juss) Roem leaves with satisfactory results.

A chiral Manganese (III) salen complex was immobilized on the walls of MCM-41 (mobile crystalline material) through the multi-grafting method. The immobilized complex was characterized by XRD, FTIR, UV-Vis, ICP and Nitrogen sorption, and was applied to the asymmetric epoxidation of unfuctionalized alkenes including 1,2-dihydronaphthalene, α-methylstyrene, cis-β-methylstyrene, styrene using NaClO and m-chloroperbenzoic acid (m-CPBA) as oxidants respectively. The immobilized complex showed good activity and enantioselectivity in the epoxidation of 1,2-dihydronaphthalene by using NaClO as oxidant. It could also be run for 4 times in the epoxidation of α-methylstyrene without obvious loss of activity or enantiomeric excess.

Self-assembly of semi-flexible/flexible block copolymers in a selective solvent is examined using a set of diblock copolymers where the chain microstructure of the semi-flexible block is manipulated in order to tune chain stiffness. Conceptually, the reduced conformational space of the semi-flexible block is anticipated to alter the way the chains pack, potentially changing the structure of self-assembled aggregates in comparison to flexible diblock copolymer analogs. Semi-flexible/flexible diblock copolymers comprised of poly(styrene)-block-poly(1,3-cyclohexadiene) (PS-b-PCHD) having systematic changes in chain microstructure, as captured by the ratio of 1,4/1,2-linkages between cyclohexenyl repeat units, and molecular weight of the PCHD blocks were synthesized using anionic polymerization. These diblocks were dissolved in tetrahydrofuran (THF), which is a preferential solvent for PS, and the structures formed were examined using laser light scattering and complementary imaging techniques. Results show that PS-b-PCHD copolymers with a chain microstructure of 90% 1,4/10% 1,2 linkages between cyclohexenyl repeat units (referred to simply as 90/10) are able to micellize, forming spherical structures, while diblocks of 70/30 and 50/50 1,4-to-1,2 ratios remain as single chains and ill-defined aggregates, respectively, when dissolved in THF. With inferences drawn from simple structural models, we speculate that this self-assembly behavior arises due to the change in the chain configuration with increasing content of 1,2-links in the backbone. This renders the chain with higher 1,2 content incapable of swelling in response to solvent and unable to pack into well-defined self-assembled structures.

A novel capillary electrophoresis and amperometric detection method was achieved by adding an electroactive additive (3,4-dihydroxybenzylamine, 3,4-DHBA) to the running buffer, so that both electroactive and non-electroactive food preservatives were simultaneously determined. Under the selected optimum conditions, four electroactive preservatives (methylparaben, ethylparaben, propylparaben and butylparaben) and two non-electroactive preservatives (potassium sorbate and sodium lactate) were well separated and sensitively detected with detection limits (S/N = 3) ranging from 1.06 × 10 −8 to 2.73 × 10 −6 g mL −1 . This method has been successfully employed for the determination of both electroactive and non-electroactive preservatives in several food commodities.