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Bismuth titanate (Bi4Ti3O12, BIT) exhibits a high Curie temperature and anisotropic electrical performance owing to its layered perovskite structure, and hence, it is an important ferroelectric material for high-temperature piezoelectric applications. It is crucial to understand the effects of the anisotropy in BIT-based ferroelectrics for developing novel high-temperature piezoelectric materials. In this study, a highly textured BIT ceramic was fabricated using the tape-casting technique from highly grain-oriented BIT platelets prepared by the molten salt method. The textured BIT ceramic showed a dense microstructure and high grain orientation along the (00l) plane with a texturing degree F00l = 0.86. It exhibited significant anisotropy in the electrical properties along the directions parallel and perpendicular to the axis of the tape-casting plane. Double ferroelectric hysteresis P–E loops and normal ferroelectric P–E loops were observed in the parallel and perpendicular samples, respectively. In addition to the layered crystal structure and domains, the anisotropy in the arrangement of the oxygen vacancy defects and their transport in the structure led to a significant anisotropy in the ferroelectric properties of the textured BIT ceramics. This work demonstrates the anisotropic arrangement of the oxygen vacancy defects and its effect on the electrical properties of high-temperature bismuth layer-structured ferroelectrics.

We present a facile approach for the direct attachment of cross-linked poly(2-thiopheneacetic acid) onto the surface of magnetite nanoparticles with one single carbon layer (Fe3O4@1C NPs) via self-assembly oxidative polymerization. The functional Fe3O4@1C NPs combined with poly(2-thiopheneacetic acid) [Fe3O4@1C@ poly(Th) NPs] was successfully prepared and used for magnetic solid-phase extraction (MSPE). The influence of the preparation conditions and extraction conditions were investigated in detail. The morphology and size distribution of the monolithic materials were characterized by transmission electron microscopy. Under the optimized experimental conditions, the prepared Fe3O4@1C@ poly(Th) NPs showed good extraction efficiency for canthin-6-one alkaloids. Furthermore, the results indicated that the binding specificity and selectivity of the Fe3O4@1C@ poly(Th) NPs might be attributed to electrostatic interactions and pore structure. A MSPE–HPLC method was also developed for quantitative analysis of canthin-6-one alkaloids. The developed method showed good linearity, low limit of detections, low limit of quantifications, and good reproducibility over a wide linear range. To further prove the utility, Fe3O4@1C@ poly(Th) NPs-MSPE was also used to extract canthin-6-one alkaloids from Eurycoma longifolia stems, with a recovery rate of 87.9–114%. Thus, this method is potentially applicable for the extraction of similar alkaloid compounds from medicinal herb samples.

Sulfur poisoning of cathode materials is one of the important factors to cause cathode performance degradation resulting in shortening lifetime of SOFC. The sulfur attacks alkali earth components of the rare earth-transition metal perovskite oxides, such as Ba, Ca, Sr, which reacts with SO2 to form sulfates. In this work, the La(Ni0.6Fe0.4)O3 (LNF) cathode material without alkali earth elements was employed to investigate the sulfur poisoning behavior by flowing 30 ppm SO2 at different temperatures of 500 °C–800 °C. It was found that SO2 readily reacts with the La2O3 component in LNF to form La2O2SO4 at 700 °C and 800 °C. The extent of the chemical reaction is temperature dependent. These results confirm that sulfur poisoning also occurs in cathode materials free of alkali earth components. The study prompts the exploration of new materials and new strategies for the developing new cathode materials with high sulfur tolerance.

Insects are exposed to cadmium stress since cadmium pollution has increasingly become a serious global environmental issue. However, until now few studies have paid attention to the effect of heavy metals on insect reproductive behaviors. In our study, the courtship behaviors, mating behaviors and fecundity of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) exposed to different concentrations of cadmium in artificial diets at larval stage were studied. The results showed that cadmium stress changed the courtship rhythm by significantly advancing or delaying the courtship starting time. Low dose of cadmium (0.2 mg/kg) increased the courtship frequency in the first two scotophases, but in the fourth phase, the two cadmium treatments reduced the frequency. The total courtship duration was significantly shortened in the first six scotophases except high dose of cadmium treatment (51.2 mg/kg) in the sixth dark phase. Paired adults did not mate after the seventh scotophase under low cadmium exposure, while high cadmium stress made the paired adults just copulate in the first four scotophases. The daily mating rate and total mating rate decreased with the increase in cadmium concentration. The number of eggs of low cadmium treatment was higher than that of control, but the difference was not significant; the number of eggs in high cadmium treatment was lower than that of control and low cadmium treatment. Our results indicate that cadmium exposure can disrupt the courtship rhythm for females and has negative influences on copulation behavior and high cadmium stress can reduce fecundity. Hence, the insect population increase will be affected by heavy metal pollution. Our study will provide scientific reference for environmental risk assessment of heavy metal pollution.

In the riveting-welding hybrid bonding of aluminum alloy and the Carbon Fiber Reinforced Polymer (CFRP), the welding joint morphology was one of the most important factors for the welding property. In the hybrid bonding process, laser-induced tungsten inert gas hybrid welding technology was used as the welding source, which had a plurality of parameters, such as laser power, arc current, defocused distance and welding speed and etc. The variation of each parameter could directly influence the welding properties. The prediction model of the laser power, welding current, defocused distance and welding speed on the profile of the welding joint morphology was established by using the BP neural network optimized through the genetic algorithm (GA-BP). The contour data of the welding joint was acquired by establishing the polar coordinate system. The geometric morphology of the welding joint was ideally fitted by using the cubic interpolation fitting in MATLAB. The results showed that the fitting line was close to the actual profile of the welding joint, and the prediction accuracy of the GA-BP was favorable. The mean absolute percentage error (MAPE) of each group of data did not exceed 3% while the standard deviation (STD) of that was less than 0.1. The study provided a new method to grope for energy transfer and real-time monitoring of laser induced TIG hybrid welding quality.

Carbon materials have been widely used for electrochemical analysis and include carbon nanotubes, graphene, and boron-doped diamond electrodes in addition to conventional carbon electrodes, such as those made of glassy carbon and graphite. Of the carbon-based electrodes, carbon film has advantages because it can be fabricated reproducibly and micro- or nanofabricated into electrodes with a wide range of shapes and sizes. Here, we report two categories of hybrid-type carbon film electrodes for mainly electroanalytical applications. The first category consists of carbon films doped or surface terminated with other atoms such as nitrogen, oxygen and fluorine, which can control surface hydrophilicity and lipophilicity or electrocatalytic performance, and are used to detect various electroactive biochemicals. The second category comprises metal nanoparticles embedded in carbon film electrodes fabricated by co-sputtering, which exhibits high electrocatalytic activity for environmental and biological samples including toxic heavy metal ions and clinical sugar markers, which are difficult to detect at pure carbon-based electrodes.

Photo-sensitive probes based on coumarin deserve extensive attention because of their high biocompatibility, quantum yield, and stability. The synthesis of coumarin and its derivatives is mainly based on four classical methods: Perkin synthesis, Knoevenagel synthesis, Wittig synthesis, and Pechmann synthesis. As everyone knows, fluorescent probes consist of a recognition group, a bridging group, and a luminescent group. Mechanism of fluorescent probes can be roughly summarized into four models: Chelation-induced enhanced fluorescence (CHEF), intramolecular charge transfer (ICT), photoinduced electron transfer (PET), and aggregation-induced luminescence (AIE), which can instruct the design of coumarin-based photo-sensitive probes. Since the fluorescence-based probe was first reported, probes based on coumarin have found widespread application in analytical chemistry, proving to be a selective, efficient, and convenient tool in ion monitoring, molecular monitoring, cell imaging, drug delivery, and many other fields. In this critical review, the synthetic routes of these compounds and the design for fluorescent probes were reported. Furthermore, the recent researches on the employment of coumarin in analytical chemistry were also introduced. Finally, the future research trends and application foreground of coumarin derivatives were forecasted herein.

In this paper, a series of novel tri(4-benzoylphenyl) phosphate derivatives with unique precipitation-inducing properties were synthesized and used as C-terminal supports for peptide synthesis. Mediated and assisted by tri(4-benzoylphenyl) phosphate derivatives, intermediate and target peptides could be separated conveniently via precipitation, which was likely to occur and was conducive to the rapid purification of the intermediates of peptide synthesis without the time-consuming and high-cost process of chromatographic separation and/or recrystallization. Based on these small-molecule supports, both Fmoc and Boc strategies for efficient peptide synthesis via the processes of liquid reaction and solid precipitation were proposed and demonstrated. Due to the peptide synthesis supports developed herein combined with the higher loading performance (loading value 3 mol/1 mol support) and the easily recyclable nature, and the processes of liquid reaction and solid precipitation combining the merits of both liquid-phase peptide synthesis and solid-phase peptide synthesis, a high-yielding, scalable, atom-economical and environment-friendly method of peptide synthesis was developed. The innovative method holds great promise in the fields of organic chemistry and chemical biology research, especially in peptide-based biomedical material and drug synthesis.

A high-efficiency strategy for resin-free and large scale liquid phase synthesis of the anti-SARS octapeptide AVLQSGFR is described. Herein, tri(4'-diphenylphosphonyloxylbenzoyl phenyl)phosphate (TDPBP) derivatives were designed as C-terminal supports to aid octapeptide intermediate purification without the need for chromatographic separation. Furthermore, the ACE inhibitory structure-activity relationship (SAR) of the anti-SARS octapeptide and its alanine-scanning analogues was systematically studied by in vitro assay and 3D-QSAR via molecular docking. This paper provides a new strategy for the development of peptide-based drugs. Simultaneously, a study on the ACE inhibition and structure-activity relationship of the anti-SARS octapeptide also lays a foundation for further understanding how the anti-SARS octapeptide acts as an ACE inhibitor.

Based on laser-induced tungsten inert gas hybrid welding source, the riveting–welding hybrid joining technology was applied to join Q460 high-strength steel and 6061 Al alloy. The mechanism...

There is a high need for covered esophageal stents as part of the palliative treatment for patients suffering from esophageal obstruction, a common symptom of esophageal cancer. This paper describes the development of a soft and flexible multi-functional bilayer membrane carrying paclitaxel, and the use of solution-casting and electrospinning to form this material into an esophageal stent coating. FDA-approved materials and established methods were used to shorten the certification process. A protective layer consisting of a polycaprolactone casting film and an electrospunpoly(lactide-coglycolide)/polycaprolactone/gelatin membrane was employed as a functional layer to enhance the material's hydrophilicity and cytocompatibility, as well as to control drug delivery behaviors. In vitro cytocompatibility indicated that cancer cells adhered and grew better than normal cells when competing for attachment on the surface of fibrous membranes. Cytotoxicity comparisons of paclitaxel-loaded membranes with various paclitaxel concentrations and corresponding paclitaxel solutions indicated that cancer cells were more sensitive than normal cells, and the controlled delivery of paclitaxel from drug-loaded membranes could maintain a sustained antitumor effect and cause less damage to normal cells. Animal experiments showed that the bilayered membrane increased the concentration of drug aggregation at the tumor, achieved efficient antitumor effects and reduced the side-effects of PTX. Bilayered membranes could be a promising stent coating to relieve dysphagia and improve the quality of life for esophageal cancer patients.

Uric acid (UA) is the final product of purine metabolism in humans. Elevated serum UA levels lead to the development of hyperuricemia, gout, kidney diseases, and metabolic syndrome. Accurate determination of UA plays a critical role in clinical diagnosis and laboratory investigation. An ultra-performance liquid chromatography (UPLC) with ultraviolet detection method has been developed and validated for UA analysis. Separation was achieved by a Waters ethylene bridged hybrid (BEH) Amide column (50 mm × 2.1 mm i.d., 1.7 μm) with acetonitrile and 0.1% acetic acid in deionized water in the proportion of 90 to 10 (v/v) as the mobile phase. The limit of detection and limit of quantification were 0.09 and 0.18 μmol/L, respectively. The method was validated by evaluating recovery (98.37–104.20%), accuracy (0.47–0.90%), and precision (1.24–1.81% for intra-batch and 1.76–3.98% for inter-batch). This method was then applied to UA determination in rat serum of hyperuricemia model. The results from UPLC, high-performa...

Detection and identification of the in vivo metabolites of traditional Chinese medicine by untargeted profiling strategies are often confronted with severe interference from complex endogenous substances. Here we developed an integral approach, by combining untargeted data-dependent MS2 (dd-MS2) of Q-Orbitrap mass spectrometry and predictive multiple reaction monitoring-information dependent acquisition-enhanced product ion scan (pMRM-IDA-EPI) of triple quadrupole-linear ion trap (QTRAP) mass spectrometry, aiming to detect and identify more extensive metabolites in bio-samples. Ecliptae Herba (EH) is a widely consumed medicinal herb with the effects of nourishing liver/kidney, but its metabolites in vivo have not been fully elucidated. Firstly, after UHPLC separation on an HSS T3 column, chemical fingerprinting of 70% ethanolic extract of EH was performed by untargeted dd-MS2 in negative ion mode. We could characterize 41 compounds from EH, and 24 were detectable in the plasma of rats (prototypes) after oral administration of EH extract (1 g/kg). Secondly, using echinocystic acid (triterpene), wedelolactone (coumarin), and apigenin (flavonoid) as the different parent templates, an MRM list containing 150 predicted ion-pairs was established to enhance MS2 scan by pMRM-IDA-EPI, which enabled the primary identification of up to 200 metabolites. The biotransformations mainly involve oxidation, hydrogenation, methylation, glucuronidation, sulfonation etc. Thirdly, the rat plasma samples obtained after oral administration of three pure compounds (echinocystic acid, wedelolactone and apigenin) were analyzed to verify the reliability of metabolites identification, and 11, 4, and 10 metabolites were found individually. This is the first comprehensive research on the metabolism of EH in vivo.

To achieve the synthesis of head-to-tail cyclic peptides via the liquid-phase on-support cyclization and synergistic self-cleavage strategy, 4,4’-bis(diphenylphosphinyloxyl) diphenyl ketoxime (BDKO) and 4-diphenyl phospholoxy benzyl alcohol (DPBA) were designed and prepared as small-molecular supports for greener peptide synthesis. During liquid-phase peptide synthesis on BDKO (or DPBA) support for peptide chain extension by Boc protocol, the last amino acid at the N-terminus of the peptide chain ends with a Fmoc protected amino acid. With the removal of the Fmoc group, head-to-tail cyclization and self-cleavage of the peptide chain synchronously occurred on BDKO (or DPBA) support to release the target cyclic peptide and the original support itself. They can be easily separated and purified, and the support can be recycled for reusing directly. The total synthesis of naturally occurring cyclic peptides such as Mortiamide A-E, Gramicidin S and cyclo(Phe-Pro) on BDKO (or DPBA) support in a resin-free manner was successfully demonstrated.

The tri(4'-diphenylphosphonyloxylbenzoyl phenyl) phosphate (TDPBP) derivatives were designed and developed as C-terminal supports to aid the greener and highefficient liquid-phase peptide synthesis (LPPS) without the need of unrecyclable resin and chromatographic separation, whereby the anti-SARS octapeptide (2) (AVLQSGFR) was synthesized with TDPBP-OH support via Fmoc chemistry and support-aided precipitation (SAP) technology. Furthermore, the ACE inhibition and the inhibitory structure-activity relationship (SAR) between the synthetic C-terminal amidated derivate (1), anti-SARS octapeptide (2) and its alanine-scanning sequence analogues (3) to (9) were systematically studied by HPLC analysis and 3D-QSAR via molecular docking.

Yucca schidigera Roezl (Mojave), a kind of ornamental plant belonging to the Yucca genus (Agavaceae), whose extract exhibits important roles in food, beverage, cosmetic and feed additives owing to its rich spirostanol saponins. To provide a comprehensive chemical profiling of the spirostanol saponins in it, this study was performed by using a multi-phase liquid chromatography method combining a reversed phase chromatography T3 column with a normal phase chromatography silica column for the separation and an ESI-Q-Exactive-Orbitrap MS in positive ion mode as the detector. By comparing the retention time and ion fragments with standards, thirty-one spirostanol saponins were identified. In addition, according to the summary of the chromatographic retention behaviors and the MS/MS cleavage patterns and biosynthetic pathway, another seventy-nine spirostanol saponins were speculatively identified, forty ones of which were potentially new ones. Moreover, ten novel spirostanol saponins (three pairs of (25R/S)-spirostanol saponin isomer mixtures) were targeted for isolation to verify the speculation. Then, the comprehensive chemical profiling of spirostanol saponins from Y. schidigera was reported here firstly.

Tomato (Solanum lycopersicum) is a major horticultural crop worldwide and has emerged as a preeminent model for metabolic research. Although many research efforts have focused on the analysis of metabolite differences between varieties and species, the dynamics of metabolic changes during the tomato growth cycle and the regulatory networks that underlie these changes are poorly understood. In this study, we integrated high-resolution spatio-temporal metabolome and transcriptome data to systematically explore the metabolic landscape across 20 major tomato tissues and growth stages. In the resulting MicroTom Metabolic Network, the 540 detected metabolites and their co-expressed genes could be divided into 10 distinct clusters based on their biological functions. Using this dataset, we constructed a global map of the major metabolic changes that occur throughout the tomato growth cycle and dissected the underlying regulatory network. In addition to verifying previously well-established regulatory networks for important metabolites, we identified novel transcription factors that regulate the biosynthesis of important secondary metabolites such as steroidal glycoalkaloids and flavonoids. Our findings provide insights into spatio-temporal changes in tomato metabolism and generate a valuable resource for the study of metabolic regulatory processes in model plants. High-resolution metabolome and transcriptome data were used to explore the metabolic landscape of 20 major tissues and developmental stages of MicroTom tomato. The MicroTom Metabolic Network dataset provides a global map of the tomato metabolic regulatory network throughout its life cycle and can be used to identify novel transcription factors that regulate important metabolic pathways.

Chrysanthemum (Chrysanthemum morifolium) is an ideal model species for studying petal morphogenesis because of the diversity in the flower form across varieties; however, the molecular mechanisms underlying petal development are poorly understood. Here, we show that the brassinosteroid transcription factor BRI1-EMS-SUPPRESSOR 1 (CmBES1) in chrysanthemum (C. morifolium cv. Jinba) is important for organ boundary formation because it represses organ boundary identity genes. Chrysanthemum plants overexpressing CmBES1 displayed increased fusion of the outermost ray florets due to the loss of differentiation of the two dorsal petals, which developed simultaneously with the ventral petals. RNA-seq analysis of the overexpression lines revealed potential genes and pathways involved in petal development, such as CUP-SHAPED COTYLEDON (CUC2), CYCLOIDEA 4 (CYC4), genes encoding MADS-box transcription factors and homeodomain-leucine zippers (HD-Zips) and auxin pathway-related genes. This study characterizes the role of CmBES1 in ray floret development by its modulation of flower development and boundary identity genes in chrysanthemum.

The most severe problem in bone regeneration is the defect in the interface. We prepared four types of implantation scaffolds of crosslinked gelatin (GE)/hydroxyapatite (HAp) to study the factors influencing interface interactions, they are film-crosslinked GE scaffold, gel-crosslinked GE scaffold, solid-crosslinked GE/HAp scaffold and gel-crosslinked GE/HAp scaffold. HAp could penetrate the entire GE matrix completely in four successive steps: physical preparation of a gel; chemical crosslinking; incubation in modified simulated body fluid (m-SBF) and freeze-drying. The penetrative nucleation and growth of HAp and the influencing factors in the GE matrix were investigated to ameliorate the interface interactions between organic and inorganic layers. During development of penetrative nucleation and growth, a tight connection was built between organic and inorganic layers, B-type carbonated HAp was formed after incubation with m-BSF, and the apatite content could be controlled. In summary, enhanced interface relies on not only the pre-seeded hydroxyapatite (HAp) as crystal nuclei but also the sufficient space for ions with high concentration to diffuse in.

To seek the novel application of organophosphorus compounds, the designed tri(4-formylphenyl) phosphonate (TFP) derivatives were successfully synthesized herein, which were used as C-terminal protecting groups of amino acid or greener triple-equivalent supports in liquid-phase peptide synthesis (LPPS). Through the support-aided precipitation effect of TFP derivatives, the peptide intermediates during peptide synthesis were separated and collected via rapid precipitation and facile filtration without chromatographic purification. Furthermore, the TFP derivative support can be directly recycled for reuse without further regeneration after being sheared from the target peptide.

Plecanatide is an oral guanylate cyclase-C agonist for the treatment of gastrointestinal disorders. The large-scale supply of plecanatide is restrained primarily by its industrial manufacture. Herein we developed diphenylphosphinyloxyl diphenyl ketone (DDK) derivatives as greener supports with unique precipitation-inducing properties to aid the liquid-phase total synthesis of plecanatide without the use of chromatography. Plecanatide could be obtained in high yield, and the ultimately sheared DDK derivative residue could be directly recycled or regenerated for reuse.

RNA-Seq was applied to capture the transcriptome of the leaf and root of non-treated and salinity-treated chrysanthemum cv. ‘Jinba’ plants. A total of 206,868 unigenes of mean length 849 nt and of N50 length 1363 nt was identified; of these about 64% (> 132,000) could be functionally assigned. Depending on the severity of the salinity stress, differential transcription was observed for genes encoding proteins involved in osmotic adjustment, in ion transport, in reactive oxygen species scavenging and in the regulation of abscisic acid (ABA) signaling. The root stress response was dominated by the up-regulation of genes involved in ion transport, while that of the leaf reflected the plant's effort to make osmotic adjustments and to regulate Ca2+ transport. An array of known transcription factors (WRKY, AP2/ERF, MYB, bHLH and NAC) were differentially transcribed.

CmBBX22, a transcription factor of chrysanthemum, was verified to confer drought tolerance in Arabidopsis thaliana. The BBX proteins are known to operate as regulators of plant growth and development, but as yet their contribution to the abiotic stress response has not been well defined. Here, the chrysanthemum BBX family member CmBBX22, an ortholog of AtBBX22, was found to be transcribed throughout the plant, although at varying intensity, and was induced by imposing moisture deficiency via exposure to polyethylene glycol. The heterologous, constitutive expression of this gene in Arabidopsis thaliana compromised germination and seedling growth, but enhanced the plants' ability to tolerate drought stress. In transgenic plants challenged with abscisic acid, leaf senescence was delayed and the senescence-associated genes and chlorophyll catabolic genes SAG29, NYE1, NYE2 and NYC1 were down-regulated. We speculated that CmBBX22 may serves as a regulator in mediating drought stress tolerance and delaying leaf senescence.

Background Drug delivery systems based on electrospun fibers have been under development for many years. However, studies of controllable long-term drug release from electrospun membrane systems and the underlying release mechanisms have seldom been reported. Methods In this study, electrospun membrane drug delivery systems consisting of the antibiotic ciprofloxacin hydrochloride and FDA-approved polymers are fabricated. Different second-component polymers are introduced to change the properties of a poly( d , l -lactide-co-glycolide) (PLGA) matrix, thereby altering the drug release behavior. On the basis of observations of morphology, cumulative release profiles, and determinations of release duration, the drug release kinetics and critical characteristics influencing drug release behavior are discussed. Results It is found that the drug release profiles can be divided into three stages according to the rate of drug release. Stage I is controlled by fiber swelling and diffusion according to Fick's second law. Stage II is controlled by diffusion through a fused membrane structure, which results in very slow drug release. Stage III is controlled by polymer degradation and involves release of the remaining drug. Conclusions The results of this study of release mechanisms should provide a basis for adjustments of drug release dosage and duration, thereby contributing to the development of drug delivery systems satisfying clinical requirements.

The Na+ /H+ antiporter SOS1 enhances the salinity tolerance of a number of plant species, but its involvement in the response to hypoxia is less well known. We presented chrysanthemum homologs CmSOS1 and CmRCD1 coordinately mediate waterlogging tolerance by maintaining membrane integrity and minimizing the level of reactive oxygen species.

Quassinoids, one kind of triterpenoids with multiple bioactivities such as anti-cancer, anti-malarial, anti-oxidative, anti-microbial, anti-diabetic, anti-viral, and anti-inflammatory effects, have drawn much attention in recent years. Between 2004 and 2018, the structural characteristics and plant sources of 190 quassinoids were reported. Herein, the structure-activity relationships (SARs) of quassinoids along with the anti-cancer mechanisms of four representative quassinoids, eurycomanone, bruceine D, dehydrobruceine B, and brusatol are discussed. This review might be useful for further research and development of quassinoids.

Recently, the amount of carnitine in saliva has been considered a biomarker for pancreatic cancer. Traditional analytical instrument such as liquid chromatography and mass-spectroscopy (MS) has been employed for carnitine detection. Only FET based biosensor was reported for carnitine, but the limit of detection was far above the required concentration. Here, we describe a highly sensitive and selective enzyme biosensor that we have developed for carnitine by using an enzyme-modified electrode combined with cathodic stripping voltammetry. The biosensor exhibits high sensitivity because of the preconcentration on the gold electrode of CoA, which was generated by the enzymatic reaction between carnitine and acetyl coenzyme A (acetyl-CoA) with carnitine acetyltransferase. Although both acetyl-CoA and CoA can adsorb on the gold electrode, the potential difference of reductive desorption detects CoA selectively. Under optimized conditions, the biosensor exhibited a linear range from 0.025 to 25 μM with a detection limit (S/N = 3) of 0.025 μM for carnitine determination. Moreover, the recovery experiments determination results show a stable range from 96.6 to 97.2 %. This developed carnitine biosensor has a potential in clinical detection due to the excellent performance.

Placing a physical barrier between the injured site and the adjacent tissues is a very common and highly effective approach to prevent abdominal adhesions in these days. A biodegradable trilayered barrier was fabricated to prevent formation of abdominal adhesions, in which a poly(lactide-co-glycolide)/poly(lactide)-b-poly(ethylene glycol) (PLGA/PLA-b-PEG) electrospun layer was sandwiched between layers of carboxymethyl chitosan (CMCS) sponge. The hydrophilic CMCS sponge layers with glycerin (GL) could adhere to the surface of wound easily, and present great hemostatic capability. The mechanism of the formation of adhesion related to blood clots acting with fibroblast cells was evaluated in detail. The blood clot acted as a "medium" inducing the fibroblast cells growth and proliferation, but had no special attraction on epithelial cells. CMCS sponge layer took away the blood clots during the swelling and dissolution stages. The electrospun layer promoted the growth of epithelial cells, but exhibited inhibition on the adhesion and spread of fibroblast cells, which ensured excellent effect of adhesion prevention. Evaluated by a rat model of sidewall defect-bowel abrasion, significant reductions of postoperative adhesion in its level and occurrence were observed in animals treated by the trilayered barrier.

Stainless steel wire (SSW) is a good substrate for stir bar sorptive extraction (SBSE). However, it is still a challenge to immobilize commonly used cross-linked polymers onto SSW. In this work, we present a new approach for immobilization of the cross-linked organic polymer onto SSW for jacket-free SBSE. A dopamine derivative was firstly synthesized; by introducing a mussel-inspired polydopamine process, a stable coating layer was finally generated on the surface of SSW. Secondly, the cross-linked polymer was synthesized on the polydopamine-modified SSW by using acetonitrile as the porogen, acrylamide (AA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and 2,2′-azobis (2-methylpropionitrile) as the initiator. A diluted pre-polymerization solution was carefully prepared to generate a thin layer of the polymer. The prepared poly(EGDMA-AA)-modified stir bar showed high stability and good tolerance toward stirring, ultrasonication, organic solvents, and strong acidic and basic conditions. Morphology and structure characterization of coatings were performed by scanning electron microscopy and Fourier transform infrared spectra, respectively. The prepared poly(EGDMA-AA)-modified stir bar showed great extraction efficiency toward protoberberines, with enrichment factors of 19–42. An SBSE-HPLC method was also developed for quantitative analysis of protoberberines. The method showed low limits of detection (0.06–0.15 ng mL−1), wide linear range (0.5–400 ng mL−1), good linearity (R ≥ 0.9980) and good reproducibility (RSD ≤ 3.60% for intra-day, RSD ≤ 4.73% for inter-day). The developed method has been successfully applied to determine protoberberines in herb and rat plasma samples, with recoveries of 88.53–114.61%.

Theoretical ternary phase diagrams in good agreement with experiment cloud point data of water/N,N-dimethylacetamide (DMAc)/polyamic acid (PAA), ethylene glycol (EG)/DMAc/PAA and ethanol/DMAc/PAA systems were constructed based on the extended Flory–Huggins theory of the polymer solutions. Binary interaction parameters were calculated and optimized accurately to construct the theoretical phase diagrams. The surface and cross-section microstructures of the as-spun fibers were analyzed by the dual diffusion theory and phase separation mechanism based on the ternary diagrams. With the concentration of DMAc in coagulation increasing, sponge-like and less skin–core structures with rougher surface were observed for fibers prepared from water/DMAc/PAA system, as the homogeneous region and metastable two-phase region enlarged in this case and it favors the nucleation and growth demixing mechanism. Further increasing concentration of DMAc in coagulation resulted in the formation of porous structures. On the other aspect, fibers prepared from EG/DMAc/PAA system exhibited a noncircular cross-section and an obvious skin–core structure, while circular cross-section and dense structures were obtained in fibers from ethanol/DMAc/PAA system. The results are in accordance with predicted ones based on theoretical ternary phase diagram.

Surface texturing was applied to flexible friction couples to improve their tribological behavior. Spherical convex texture was fabricated on the surface of photosensitive resin by stereolithography (SLA), the friction coefficient between the textured resin sample and smooth polydimethylsiloxane (PDMS) under the conditions of low sliding speed and dry friction was measured using a self-made frictional test bench. It was found that surface texture is capable of reducing friction at low applied normal load compared with the non textured friction couple, as well as increasing friction at high load, in addition, smaller texture radii tend to increase friction. At last, the friction mechanism of the textured flexible friction couple was discussed by establishing a mechanical model.

Co-polyimide (co-PI) fibers with outstanding mechanical properties were fabricated via thermal imidization of polyamic acids, derived from a new design of combining the amide and benzimidazole diamine monomers, 4-amino-N-(4-aminophenyl)benzamide (DABA) and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA), with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA). The crystalline structure and micromorphology of the prepared co-PI fibers were investigated by synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). The two-dimensional WAXD spectra imply that the co-PI fibers possess a structure between smectic-like and three-dimensionally ordered crystalline phase, and all the obtained fibers are highly oriented along the fiber axis. SAXS patterns exhibit a pair of meridional scattering streaks for the homo-PI (BPDA/BIA) fiber, suggesting the presence of periodic lamellar structure. The incorporation of DABA into the polymer chains destroyed the lamellar structure but led to smaller size of microvoids upon increasing DABA moiety, based on SAXS analysis. The co-PI fibers, with the molar ratio of BIA/DABA being 7/3, exhibited the optimum tensile strength and modulus of 1.96 and 108.3 GPa, respectively, attributed to the well-defined ordered and dense structure. The chemical structure and molecular packing significantly affected the thermal stability of fibers, resulting in the different glass transition temperatures (T-g) from 350 to 380 degrees C. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 183-191

In this work, we interestingly happened to observe the adsorption of stainless steel sample loop of HPLC. The adsorptive behaviors of the stainless steel loop toward different kinds of compounds were studied, including polycyclic aromatic hydrocarbons (PAHs), halogeno benzenes, aniline derivatives, benzoic acid derivatives, phenols, benzoic acid ethyl ester, benzaldehyde, 1-phenyl-ethanone and phenethyl alcohol. The adsorptive mechanism was probably related to hydrophobic interaction, electron-rich element–metal interaction and hydrogen bond. Universal adsorption of stainless steels was also testified. Inspired by its strong adsorptive capability, bare stainless steel loop was developed as a modification-free in-tube device for solid-phase microextraction (SPME), which served as both the substrate and sorbent and possessed ultra-high strength and stability. Great extraction efficiency toward PAHs was obtained by stainless steel loop without any modification, with enrichment factors of 651–834. By connecting the stainless steel loop onto a six-port valve, an online SPME–HPLC system was set up and an SPME–HPLC method has been validated for determination of PAHs. The method has exceptionally low limits of detection of 0.2–2 pg/mL, which is significantly lower than that of reported methods with different kinds of sorbents. Wide linear range (0.5–500 and 2–1000 pg/mL), good linearity (R2 ≥ 0.9987) and good reproducibility (RSD ≤ 2.9%) were also obtained. The proposed method has been applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 88.5% to 93.8%.

Stainless steel wire is a good substrate for jacket-free stir bar sorptive extraction (SBSE). In this work, we present the first example of chemical modification of graphene on stainless steel wire (SSW) for SBSE. Bio-inspired polydopamine was firstly modified on the SSW covalently; then graphene oxide was introduced and reacted with amino groups of polydopamine layer. The modification of polydopamine and graphene can be repeated by a layer-by-layer strategy, resulting in control of the thickness of graphene layer and increase of extraction capability. The prepared covalently immobilized graphene-stainless steel wire (G-SSW) exhibited good stability under stirring, ultrasonication and treatment with commonly used organic solvents, basic and acidic solutions. Application as stir bar for SBSE, G-SSW was found to possess good extraction efficiency towards pollutant polyaromatic hydrocarbons (PAHs), with enrichment factors from 10086 to 16896. After optimization of conditions, G-SSW based SBSE was coupled HPLC for determination of PAHs in environmental and food samples. The quantitative method has low limits of detection of 0.2-50pg/mL, which is better than some reported SBSE-HPLC methods. The method shows wide linear range (200-5000, 10-1000 and 1-1000pg/mL), good linearity (r≥0.9950) and good reproducibility (RSD≤4.97%). The method has been applied to soil and food samples, with good selectivity and good recoveries ranging from 88.5-113.6%.

The rheological behaviour of polyamic acid (PAA) solution was studied using N,N-dimethylacetamide (DMAc) as a solvent. The results showed that the PAA/DMAc solution with solid contents of 11–15 wt-% was a shear-thinning fluid. The non-Newtonian behaviour of the solution increased with increasing PAA concentration and decreasing temperature. The complex viscosity (η*) increases upon the concentration of PAA solution. Storage modulus and loss modulus increase with increasing frequency and an obvious plateau modulus appears, exhibiting a typical solid-like behaviour at high frequencies. The PAA solution with higher solid content shows lower tangent loss angle (tan δ), higher storage modulus and loss modulus. Increasing temperature plays an opposite role in increasing polymer concentration on complex viscosity, storage modulus, loss modulus and tan δ.

Rigid-rod polyimides (PI) containing benzimidazole moieties were synthesized and spun into fibers by a wet-spinning method. The resultant fibers exhibited an optimum tensile strength of 2.15 GPa and an initial modulus of 105 GPa with a low elongation of 2.2%. The PI fibers consisting of various ratios of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB) and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) were investigated by Fourier transform infrared spectroscopy and two-dimensional wide angle X-ray diffraction (2D WAXD). Direct evidence of hydrogen-bonding involving the NH groups of BIA and the imide carbonyls is presented. Qualitative and quantitative information of this molecular interaction was obtained and discussed. This has been considered as a main factor responsible for the significantly improved mechanical properties of the PI fibers. 2D WAXD and molecular mechanics modeling were used to simulate the structure of the aromatic PI fibers. As a result, the addition of BIA in the main chains is to increase the regularity of the molecule packing, which plays an important role in the enhanced strength of the PI fibers with more BIA loadings.

Functionalized multiwalled carbon nanotubes (f-MWNTs)/polyamic acid (PAA) solution was prepared via in situ polymerization. Transmission electron microscopy conformed the homogeneous dispersion of f-MWNTs in the polymer matrix. The diffusion rate of N,N-dimethylacetamide in f-MWNT/PAA solution into water shows a significant acceleration upon f-MWNT loadings. PAA composite fibers containing various loadings of f-MWNTs were produced by traditional wet-spinning process, and then the precursor fibers were converted to corresponding polyimide fibers via thermal imidization. Scanning electron microscopy, atomic force microscopy and X-ray scattering were employed to characterize the composite fibers. The thermal stability of polyimide fibers shows an obvious improvement with the incorporation of f-MWNTs. Meanwhile, f-MWNTs hinder the motivation of macromolecular chains, resulting in a reduced heat-shrinkage of the composite fibers. Exceptional enhanced mechanical properties of composite fibers were obtained due to the introduction of f-MWNT nanofillers.

Implantation of sustained antibacterial system after abdominal surgery could effectively prevent complicated intra-abdominal infection. In this study, a simple blended electrospun membrane made of poly(D,L-lactic-co-glycolide) (PLGA)/poly(dioxanone) (PDO)/Ciprofloxacin hydrochloride (CiH) could easily result in approximately linear drug release profile and sustained antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The addition of PDO changed the stack structure of PLGA, which in turn influenced the fiber swelling and created drug diffusion channels. It could be a good candidate for reducing postoperative infection or be associated with other implant to resist biofilm formation.

A series of co-polyimide fibers were prepared by thermal imidization of copolyamic acids derived from 3,3′,4,4′-biphenyltertracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) in various molar ratios with 2-(4-aminophenyl)−5-aminobenzimidazole (BIA). The dynamic mechanical behaviors of these polyimide (PI) fibers revealed that the glass transition temperature (Tg) was significantly improved upon increasing PMDA content. Heat-drawing process led to dramatic change on the glass transition behavior of BPDA/BIA system, but had a small impact on BPDA/PMDA/BIA co-polyimide fibers. This difference for PI fibers is attributed to the different degree of ordered structure of the fibers affected by heat-drawing. The incorporation of PMDA obviously improved the dimensional stability against high temperature, due to the restricted movement of polymer chains. In addition, the obtained fibers show excellent mechanical and thermal properties because of the strong hydrogen bonding due to the incorporation of benzimidazole moieties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41474.