Facile design of structurally robust, highly conductive and well-flexible hybrid film based on MXene, cellulose nanofiber and poly (3,4-ethylenedioxythiphoenes):polystyrene sulfonate for supercapacitors.

Robust, conductive and flexible electrode materials have been the focus of attention in portable, wearable electronics. However, it is still a significant challenge to achieve synergistic development of multiple properties simultaneously. Herein, we propose a combination of microscale design and nanostructures strategy to prepare MXene/cellulose nanofiber-poly (3,4-ethylenedioxythiphoenes):polystyrene sulfonate (Ti3C2Tx/CNF-PEDOT:PSS, TC-P) hybrid film by a simple in-situ polymerization and vacuum filtration process. CNF serves as the supporting skeleton of PEDOT:PSS, effectively mitigating its self-aggregation and structural deformation due to the expansion/contraction of the polymer network. And the CNF-PEDOT:PSS composite is capable to open up the interlayer space of Ti3C2Tx, which reduces the self-stacking of Ti3C2Tx nanosheets. The strong interactions among the three components enable the hybrid film electrode to possess both flexibility and high electrochemical properties. As a result, the film electrode exhibits a remarkable tensile strength of 77.4 MPa and an excellent conductivity of 162.5 S cm-1, as well as an outstanding areal specific capacitance of 896 mF cm-2 at 4 mA cm-2. Moreover, the assembled symmetric supercapacitor (SSC) device displays a large areal energy density of 62 µWh cm-2 at a power density of 800 µW cm-2 and demonstrates a long cycle life with 85.1 % capacitance retention after 10,000 GCD cycles. This study provides an effective strategy to balance mechanical flexibility and electrochemical properties, providing an inspiration to prepare flexible electrodes that are widely applied in a new generation of portable, wearable electronics.

High stretchable and tough xylan-g-gelatin hydrogel via the synergy of chemical cross-linking and salting out for strain sensors.

Stretchable and tough hydrogels have been extensively used in tissue engineering scaffolds and flexible electronics. However, it is still a significant challenge to prepare hydrogels with both tensile strength and toughness by utilizing xylan, which is abundant in nature. Herein, we present a novel hydrogel of carboxymethyl xylan(CMX) graft gelatin (G) and doped with conductive hydroxyl carbon nanotubes (OCNT). CMX and G are combined through amide bonding as well as intermolecular hydrogen bonding to form a semi-interpenetrating hydrogel network. The hydrogel was further subjected to salting-out treatment, which induced the aggregation of the CMX-g-G molecular chain and the formation of chain bundles to toughen the hydrogel, the tensile strain, tensile stress, and toughness of CMX-g-G hydrogels were 1.547 MPa, 324 %, and 2.31 MJ m-3, respectively. In addition, OCNT was used as a conductive filler to impart electrical conductivity and further improve the mechanical properties of CMX-g-G/OCNT hydrogel, and a tensile strength of 1.62 MPa was obtained. Thus, the synthesized CMX-g-G/OCNT hydrogel can be used as a reliable and sensitive strain sensor for monitoring human activity. This study opens up new horizons for the preparation of xylan-based high-performance hydrogels.

Artificial intelligence-based diagnosis of standard endoscopic ultrasonography scanning sites in the biliopancreatic system: a multicenter retrospective study.

BACKGROUND: There are challenges for beginners to identify standard biliopancreatic system anatomical sites on endoscopic ultrasonography (EUS) images. Therefore, the authors aimed to develop a convolutional neural network (CNN)-based model to identify standard biliopancreatic system anatomical sites on EUS images. METHODS: The standard anatomical structures of the gastric and duodenal regions observed by EUS was divided into 14 sites. The authors used 6230 EUS images with standard anatomical sites selected from 1812 patients to train the CNN model, and then tested its diagnostic performance both in internal and external validations. Internal validation set tests were performed on 1569 EUS images of 47 patients from two centers. Externally validated datasets were retrospectively collected from 16 centers, and finally 131 patients with 85 322 EUS images were included. In the external validation, all EUS images were read by CNN model, beginners, and experts, respectively. The final decision made by the experts was considered as the gold standard, and the diagnostic performance between CNN model and beginners were compared. RESULTS: In the internal test cohort, the accuracy of CNN model was 92.1-100.0% for 14 standard anatomical sites. In the external test cohort, the sensitivity and specificity of CNN model were 89.45-99.92% and 93.35-99.79%, respectively. Compared with beginners, CNN model had higher sensitivity and specificity for 11 sites, and was in good agreement with the experts (Kappa values 0.84-0.98). CONCLUSIONS: The authors developed a CNN-based model to automatically identify standard anatomical sites on EUS images with excellent diagnostic performance, which may serve as a potentially powerful auxiliary tool in future clinical practice.

Sodium carboxymethylcellulose/MXene/zeolite imidazolium framework-67-derived 3D porous carbon aerogel for high-performance asymmetric supercapacitors.

Herein, we propose a carbon/TiO2/Co3O4 (CTC) composite carbon aerogel with a 3D porous conductive network structure derived from sodium carboxymethylcellulose (CMC)/Mxene (Ti3C2Tx)/zeolite imidazolium framework-67 (ZIF-67). Among them, CMC is used as the carbon skeleton, which can reduce the powdering caused by volume change and improve the cycle stability. Ti3C2Tx acts as the conductive agent and dispersant for ZIF-67, exposing more reactive sites while constructing fast conductive channels to enhance electrochemical performance. The microstructure of the CTC carbon aerogel is modulated by controlling the mass ratio of Ti3C2Tx to ZIF-67, and the carbon aerogel with a mass ratio of 2:3 (CTC-2:3) is experimentally demonstrated to have the best electrochemical performance. The CTC-2:3 electrode exhibits a high specific capacitance of 481.7 F g-1 at 1 A g-1 and possesses a rate performance of 78.9 % at 10 A g-1. The assembled asymmetric supercapacitor (ASC, CTC-2:3//Ti3C2Tx) delivers an energy density of 48.4 Wh kg-1 at a power density of 699.8 W kg-1. Moreover, the ASC device maintains 85.3 % initial capacitance and 99.1 % coulombic efficiency after 10,000 GCD cycles, indicating good cycling stability. This facile design pathway provides a new insight for the development of high-performance electrode materials.

Carboxymethylcellulose/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate membrane after dimethyl sulfoxide treatment for flexible and high electrochemical performance asymmetric supercapacitors.

As the requirements for wearable electronic devices continue to increase, the development of bendable and foldable supercapacitors is becoming critical. However, it is still challenging to design free-standing electrodes with flexibility and high electrical conductivity. Herein, using carboxymethylcellulose (CMC) as the biological template and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as the electroactive material, a flexible CMC/PEDOT:PSS membrane with a cross-linked mesh structure was firstly synthesized by a facile in-situ polymerization and vacuum filtration process. Subsequently, the CMC/PEDOT:PSS membrane was further treated with dimethyl sulfoxide (DMSO) to remove the excess PSS, thereby enhancing their electrochemical performance. The results showed that the best performing hybrid membrane had good mechanical properties (tensile strength of 48.1 MPa) and high electrical conductivity (45.1 S cm-1). The assembled asymmetric supercapacitor (ASC) is capable of delivering an energy density of 181.9 µW h cm-2 at a power density of 750 µW cm-2 and maintains an initial capacitance of 93.4 % and a coulombic efficiency of 100 % after 10,000 GCD cycles, demonstrating an ultra-long cycle life. Moreover, good electrochemical properties can be retained even in the bent and folded state. Therefore, the hybrid membrane electrode with both flexibility and high electrochemical performance has great potential for application in wearable electronics.

Flexible and alternately layered high electrochemical active electrode based on MXene, carboxymethylcellulose, and carbon nanotube for asymmetric micro-supercapacitors.

Recent studies have shown that Ti-based MXene has great potential for electrochemical energy storage applications, including Li-ion batteries and micro-supercapacitors. However, self-stacking and weak interlayer interactions lead to poor electrochemical properties. Herein, a simple one-step vacuum filtration method was used to prepare a MXene/carboxymethylcellulose/carbon nanotube (Ti3C2Tx/CMC/CNT) hybrid membrane. Due to the unique adhesion and flexibility of CMC, it can be interwoven with CNT to form an interconnected mesh structure, which on the one hand mitigates the self-aggregation of CNT, and on the other hand, the CNT entangled on the surface of CMC imparts its electrical conductivity. Moreover, the -OH of CMC can form hydrogen bonds with the reactive terminal groups (-O, -OH, -F) of Ti3C2Tx, resulting in the tight anchoring of CMC and CNT to Ti3C2Tx nanosheet layers and bridging adjacent Ti3C2Tx nanosheets to form a complete conductive pathway. As a result, the mechanical property test indicates that the Ti3C2Tx/CMC/CNT hybrid film could achieve a maximum tensile strength of 64.9 MPa. Furthermore, an asymmetric micro-supercapacitor (MSC) using Ti3C2Tx/CMC/CNT as the cathode and reduced graphene oxide/carboxymethylcellulose/polypyrrole (RGO/CMC/PPy) as the anode was fabricated, which exhibited a high energy density of 258.8 µWh cm-2 at a power density of 750 µW cm-2, and an ultra-long cycle life (93.2% capacitance retention after 15,000 GCD cycles). The simple and scalable preparation process makes this MSC device very promising for commercial electronics applications.

Enrichment of miR-17-5p enhances the protective effects of EPC-EXs on vascular and skeletal muscle injury in a diabetic hind limb ischemia model.

BACKGROUND/AIMS: Diabetes mellitus (DM) is highly susceptible to diabetic hind limb ischemia (DHI). MicroRNA (MiR)-17-5p is downregulated in DM and plays a key role in vascular protection. Endothelial progenitor cell (EPC)-released exosomes (EPC-EXs) contribute to vascular protection and ischemic tissue repair by transferring their contained miRs to target cells. Here, we investigated whether miR-17-5p-enriched EPC-EXs (EPC-EXsmiR-17-5p) had conspicuous effects on protecting vascular and skeletal muscle in DHI in vitro and in vivo. METHODS: EPCs transfected with scrambled control or miR-17-5p mimics were used to generate EPC-EXs and EPC-EXsmiR-17-5p. Db/db mice were subjected to hind limb ischemia. After the surgery, EPC-EXs and EPC-EXsmiR-17-5p were injected into the gastrocnemius muscle of the hind limb once every 7 days for 3 weeks. Blood flow, microvessel density, capillary angiogenesis, gastrocnemius muscle weight, structure integrity, and apoptosis in the hind limb were assessed. Vascular endothelial cells (ECs) and myoblast cells (C2C12 cells) were subjected to hypoxia plus high glucose (HG) and cocultured with EPC-EXs and EPC-EXsmiR-17-5p. A bioinformatics assay was used to analyze the potential target gene of miR-17-5p, the levels of SPRED1, PI3K, phosphorylated Akt, cleaved caspase-9 and cleaved caspase-3 were measured, and a PI3K inhibitor (LY294002) was used for pathway analysis. RESULTS: In the DHI mouse model, miR-17-5p was markedly decreased in hind limb vessels and muscle tissues, and infusion of EPC-EXsmiR-17-5p was more effective than EPC-EXs in increasing miR-17-5p levels, blood flow, microvessel density, and capillary angiogenesis, as well as in promoting muscle weight, force production and structural integrity while reducing apoptosis in gastrocnemius muscle. In Hypoxia plus HG-injured ECs and C2C12 cells, we found that EPC-EXsmiR-17-5p could deliver their carried miR-17-5p into target ECs and C2C12 cells and subsequently downregulate the target protein SPRED1 while increasing the levels of PI3K and phosphorylated Akt. EPC-EXsmiR-17-5p were more effective than EPC-EXs in decreasing apoptosis and necrosis while increasing viability, migration, and tube formation in Hypoxia plus HG-injured ECs and in decreasing apoptosis while increasing viability and myotube formation in C2C12 cells. These effects of EPC-EXsmiR-17-5p could be abolished by a PI3K inhibitor (LY294002). CONCLUSION: Our results suggest that miR-17-5p promotes the beneficial effects of EPC-EXs on DHI by protecting vascular ECs and muscle cell functions.

Advances in the application of molecular diagnostic techniques for the detection of infectious disease pathogens (Review).

Infectious diseases are a major global cause of morbidity and mortality, seriously affecting public health and socioeconomic stability. Since infectious diseases can be caused by a wide variety of pathogens with similar clinical manifestations and symptoms that are difficult to accurately distinguish, selecting the appropriate diagnostic techniques for the rapid identification of pathogens is crucial for clinical disease diagnosis and public health management. However, traditional diagnostic techniques have low detection rates, long detection times and limited automation, which means that they do not meet the requirements for rapid diagnosis. Recent years have seen continuous developments in molecular detection technology, which has a higher sensitivity and specificity, shorter detection time and increased automation, and performs an important role in the early and rapid detection of infectious disease pathogens. The present study summarizes recent progress in molecular diagnostic technologies such as PCR, isothermal amplification, gene chips and high­throughput sequencing for the detection of infectious disease pathogens, and compares the technical principles, advantages and disadvantages, applicability and costs of these diagnostic techniques.

MiR-17-5p Mediates the Effects of ACE2-Enriched Endothelial Progenitor Cell-Derived Exosomes on Ameliorating Cerebral Ischemic Injury in Aged Mice.

Aging is one of the key mechanisms of vascular dysfunction and contributes to the initiation and progression of ischemic stroke (IS). Our previous study demonstrated that ACE2 priming enhanced the protective effects of exosomes derived from endothelial progenitor cells (EPC-EXs) on hypoxia-induced injury in aging endothelial cells (ECs). Here, we aimed to investigate whether ACE2-enriched EPC-EXs (ACE2-EPC-EXs) could attenuate brain ischemic injury by inhibiting cerebral EC damage through their carried miR-17-5p and the underlying molecular mechanisms. The enriched miRs in ACE2-EPC-EXs were screened using the miR sequencing method. EPC-EXs, ACE2-EPC-EXs, and ACE2-EPC-EXs with miR-17-5p deficiency (ACE2-EPC-EXsantagomiR-17-5p) were administered to transient middle cerebral artery occlusion (tMCAO)-operated aged mice or coincubated with hypoxia/reoxygenation (H/R)-treated aging ECs. The results showed that (1) the level of brain EPC-EXs and their carried ACE2 were significantly decreased in aged mice compared to in young mice, and (2) after tMCAO, aged mice displayed increases in brain cell senescence, infarct volume, and neurological deficit score (NDS) and a decrease in cerebral blood flow (CBF). (3) Compared with EPC-EXs, ACE2-EPC-EXs were enriched with miR-17-5p and more effective in increasing ACE2 and miR-17-5p expression in cerebral microvessels, accompanied by obvious increases in cerebral microvascular density (cMVD) and cerebral blood flow (CBF) and decreases in brain cell senescence, infarct volume, neurological deficit score (NDS), cerebral EC ROS production, and apoptosis in tMCAO-operated aged mice. Moreover, silencing of miR-17-5p partially abolished the beneficial effects of ACE2-EPC-EXs. (4) In H/R-treated aging ECs, ACE2-EPC-EXs were more effective than EPC-EXs in decreasing cell senescence, ROS production, and apoptosis and increasing cell viability and tube formation. In a mechanistic study, ACE2-EPC-EXs more effectively inhibited PTEN protein expression and increased the phosphorylation of PI3K and Akt, which were partially abolished by miR-17-5p knockdown. Altogether, our data suggest that ACE-EPC-EXs have better protective effects on ameliorating aged IS mouse brain neurovascular injury by inhibiting cell senescence, EC oxidative stress, apoptosis, and dysfunction by activating the miR-17-5p/PTEN/PI3K/Akt signaling pathway.

Free-standing reduced graphene oxide/carboxymethylcellulose-polyaniline (RGO/CMC-PANI) hybrid film electrode for high-performance asymmetric supercapacitor device.

This work demonstrates a facile and effective strategy for the preparation of a reduced graphene oxide/carboxymethylcellulose-polyaniline (RGO/CMC-PANI) hybrid film electrode. Specifically, through the hydrogen bonding interaction between -OH of CMC molecules and -NH2 of aniline monomer, PANI grows in an ordered manner on the surface of CMC, which effectively alleviates the structural collapse of PANI during the continuous charge/discharge process. After compounding with RGO, CMC-PANI bridges adjacent RGO sheets to form a complete conductive path, and opens the gap between RGO sheet layers to obtain fast ion channels. As a result, the RGO/CMC-PANI electrode exhibits excellent electrochemical performance. Moreover, an asymmetric supercapacitor was fabricated using RGO/CMC-PANI as the anode and Ti3C2Tx as the cathode. The results show that the device has a large specific capacitance of 450 mF cm-2 (81.8 F g-1) at 1 mA cm-2 and a high energy density of 140.6 µWh cm-2 at a power density of 749.9 µW cm-2. Besides, 87.3 % initial capacitance and 100 % good coulombic efficiency can be maintained even after 20,000 GCD cycles. Therefore, the device has a broad application prospect in the field of new-generation microelectronic energy storage.

Establishment and Evaluation of Recombinant Expression of HCV Transmembrane Protein (p7) and Detection of Anti-p7 Antibody in Serum of HCV-Infected Patients by Chemiluminescence.

OBJECTIVE: Our aim was to establish a chemiluminescence method for detecting anti-transmembrane protein (p7) antibody in the serum of patients with hepatitis C virus (HCV) infection. METHODS: The p7 gene was amplified by polymerase chain reaction using the plasmid PUC-p7 containing the p7 nucleic acid sequence of the HCV 1b genotype as the template, and recombinant plasmid pGEX-KG-p7 was constructed. After p7 fusion, the protein was induced and expressed in the prokaryote, extracted, and purified; the anti-p7 antibody detection kit was prepared, and its efficacy was evaluated. RESULTS: The plasmid pGEX-KG-p7 was constructed correctly, and p7 fusion protein was obtained. The methodological indexes of the kit, the precision test, blank limit and detection limit, etc, met the requirements. The positive rate of serum anti-p7 antibody in 45 patients with HCV infection was 20%. CONCLUSIONS: The kit can be used in screening diagnosis, condition monitoring, prognosis, and disease mechanism and epidemiological study of HCV infection. The p7 protein has immune response in HCV-infected patients.

Enrichment of miR-17-5p enhances the protective effects of EPC-EXs on vascular and skeletal muscle injury in a diabetic hind limb ischemia model

BACKGROUND/AIMS: Diabetes mellitus (DM) is highly susceptible to diabetic hind limb ischemia (DHI). MicroRNA (MiR)-17-5p is downregulated in DM and plays a key role in vascular protection. Endothelial progenitor cell (EPC)-released exosomes (EPC-EXs) contribute to vascular protection and ischemic tissue repair by transferring their contained miRs to target cells. Here, we investigated whether miR-17-5p-enriched EPC-EXs (EPC-EXsmiR-17-5p) had conspicuous effects on protecting vascular and skeletal muscle in DHI in vitro and in vivo. METHODS: EPCs transfected with scrambled control or miR-17-5p mimics were used to generate EPC-EXs and EPC-EXsmiR-17-5p. Db/db mice were subjected to hind limb ischemia. After the surgery, EPC-EXs and EPC-EXsmiR-17-5p were injected into the gastrocnemius muscle of the hind limb once every 7 days for 3 weeks. Blood flow, microvessel density, capillary angiogenesis, gastrocnemius muscle weight, structure integrity, and apoptosis in the hind limb were assessed. Vascular endothelial cells (ECs) and myoblast cells (C2C12 cells) were subjected to hypoxia plus high glucose (HG) and cocultured with EPC-EXs and EPC-EXsmiR-17-5p. A bioinformatics assay was used to analyze the potential target gene of miR-17-5p, the levels of SPRED1, PI3K, phosphorylated Akt, cleaved caspase-9 and cleaved caspase-3 were measured, and a PI3K inhibitor (LY294002) was used for pathway analysis. RESULTS: In the DHI mouse model, miR-17-5p was markedly decreased in hind limb vessels and muscle tissues, and infusion of EPC-EXsmiR-17-5p was more effective than EPC-EXs in increasing miR-17-5p levels, blood flow, microvessel density, and capillary angiogenesis, as well as in promoting muscle weight, force production and structural integrity while reducing apoptosis in gastrocnemius muscle. In Hypoxia plus HG-injured ECs and C2C12 cells, we found that EPC-EXsmiR-17-5p could deliver their carried miR-17-5p into target ECs and C2C12 cells and subsequently downregulate the target protein SPRED1 while increasing the levels of PI3K and phosphorylated Akt. EPC-EXsmiR-17-5p were more effective than EPC-EXs in decreasing apoptosis and necrosis while increasing viability, migration, and tube formation in Hypoxia plus HG-injured ECs and in decreasing apoptosis while increasing viability and myotube formation in C2C12 cells. These effects of EPC-EXsmiR-17-5p could be abolished by a PI3K inhibitor (LY294002). CONCLUSION: Our results suggest that miR-17-5p promotes the beneficial effects of EPC-EXs on DHI by protecting vascular ECs and muscle cell functions.

Carboxymethylcellulose-polyaniline/carbon nanotube (CMC-PANI/CNT) film as flexible and highly electrochemical active electrode for supercapacitors.

Herein, we demonstrate a flexible, structural robust and highly electrochemical active film electrode based on evenly distributed carboxymethylcellulose-polyaniline/carbon nanotube (CMC-PANI/CNT) for supercapacitors. In this process, vertically aligned PANI nanoparticles grow in an orderly manner on CMC fibers. The highly dispersed CNT nanomaterials are then introduced by simple layer-by-layer assembly, eventually forming an interwoven network structure. Mechanical tests have shown that the obtained CMC-PANI/CNT film exhibit excellent robustness and flexibility, and can be used directly as electrodes without any conductive additives and binders. The CMC-PANI/CNT electrode with optimal CMC, PANI and CNT contents demonstrates an excellent area specific capacitance of 3106.3 mF cm-2 at 5 mA cm-2 and a gravimetric specific capacitance of 348.8 F g-1 at 0.5 A g-1. Furthermore, the symmetric supercapacitor (SSC) assembled with CMC-PANI/CNT exhibits a high energy density of 99.89 µW h cm-2 at a power density of 400.02 µW cm-2, and a good cycling stability (with capacitance retention of 89.2 % after 5000 cycles). The cost-effective and eco-friendly preparation method of free-standing CMC-PANI/CNT film electrodes provide a novel insight for developing flexible energy storage devices.

In situ growth of chrysanthemum-like NiCo2S4 on MXenes for high-performance supercapacitors and a non-enzymatic H2O2 sensor.

In this work, we developed a novel strategy to couple chrysanthemum-like NiCo2S4in situ-grown MXene hybrids into a three-dimensional (3D) sandwich architecture hybrid as an electrode material for high-performance asymmetric supercapacitors and non-enzymatic H2O2 sensors. In the 3D sandwich architecture hybrid, the NiCo2S4 particles were encapsulated by MXene layers, which enhanced the interlayer space of MXene, significantly improving the electrochemical properties. In particular, the MXene/NiCo2S4 1 : 2 electrode achieved a specific capacitance of 1266 F g-1 at 0.5 A g-1 and maintained 95.21% of its initial value after 10 000 cycles. Furthermore, an asymmetrical supercapacitor was also fabricated using MXene/NiCo2S4 1 : 2 as the positive electrode and activated carbon (AC) as the negative electrode (MXene/NiCo2S4 1 : 2//AC), which exhibited exceptional electrochemical performance. MXene/NiCo2S4 1 : 2//AC exhibited a large specific capacitance of 621 F g-1 at 0.5 A g-1 and energy density of 72.82 W h kg-1 at a power density of 0.635 kW kg-1. In addition, MXene/NiCo2S4 1 : 2 was employed as a non-enzymatic sensor for the electrochemical detection of H2O2, which exhibited a high sensitivity of 0.267 µA µM-1 cm-2 and noteworthy low detection limit of 0.193 µM based on 3 signal-noise ratios. This research provides a facile route for the in situ growth of bimetallic sulfides on MXenes as electrode materials for energy storage and electrochemical detection.

The effects of deposition time and current density on the electrochemical performance of flexible and high-performance MnO2@PFG composite electrodes.

A novel composite electrode has been fabricated by the direct deposition of MnO2 onto graphene networks surrounding a paper fiber (PFG). The paper fiber between graphene sheets could be used as a flexible substrate for MnO2 nanoparticles, and the microscopic morphologies and electrochemical performances of the MnO2@PFG electrodes were tuned via regulating the deposition current densities and deposition times. 3D graphene on PFG served as a highly conductive backbone with a high surface area for the deposition of the MnO2 nanoparticles, which provided high accessibility to electrolyte ions for shortening the diffusion paths. The MnO2-10-600 s@PFG composite electrode achieved a maximum specific capacitance of 878.6 mF cm-2 with an MnO2 loading mass of 3.62 mg cm-2 (specific capacitance of 187.7 F g-1) at a current density of 0.5 mA cm-2 in a 1 M NaSO4 aqueous solution. Additionally, the MnO2-10-600 s@PFG composite material with the most favorable composite ratio exhibited the highest energy density of 61.01 mW h cm-2, maximum power density of 1249.78 mW cm-2, excellent capacitance retention with no more than 7% capacitance loss after 10 000 cycles and good mechanical flexibility (about 91.06% of its original capacitance after 500 bending times). By combining the electric double layer capacitance of graphene networks with the pseudocapacitance of the MnO2 nanostructures, the flexible electrode showed much enhanced electrochemical capacitance behaviors with robust tolerance to mechanical deformation; thus, it is promising for being woven into textiles for wearable electronics.

Self-assembly of flexible graphene hydrogel electrode based on crosslinked pectin-cations.

Pectin, natural polysaccharide biopolymer, was chelated with cations (Mg2+/Ca2+) to form an interwoven framework. Herein, the graphene hydrogel electrodes were self-assembled by the synergistic effects of pectin-cations. The optimum combination proportion was determined, the Mg2+/Ca2+-pectin matrix cross-linked graphene hydrogel (Mg2+/Ca2+-PGH) electrodes exhibited a large specific capacitance of about 839.2 F g-1 with high coulombic efficiency of 191.8% at a current density of 1 A g-1. The assembled flexible supercapacitor displayed excellent stability (capacitance retention of 98.5% after 2000 charge/discharge cycles) and flexibility (the specific capacitance remained 98.4% of its original value after 500 folding/unfolding cycles). Such flexible and high-performance Mg2+/Ca2+-PGH electrodes are attractive in the field of lightweight, miniature and wearable energy storage devices.

High-performance MnO2-deposited graphene/activated carbon film electrodes for flexible solid-state supercapacitor.

High theoretical capacitance of MnO2 nanoparticles were successfully electrodeposited on the conductive graphene/activated carbon (GN/AC) composite film, and the urchin type MnO2 microspheres were controlled by adjusting the electro-deposition reaction times. The GN/AC/MnO2-1200s composite electrodes exhibited a maximum specific capacitance of 1231 mF/cm2 (MnO2 loading mass of 7.65 mg/cm2 and the mass specific capacitance of 123 F/g) at a current density of 0.5 mA/cm2. The assembled flexible solid-state symmetric supercapacitor had a good mechanical flexibility (about 88.6% of its original capacitance after 500 bending times) and prominent cycling stability (about 82.8% retention in capacitance over 10000 cycles). More importantly, the device could possess a maximum energy density of 0.27 mW h/cm3 and a maximum power density of 0.02 W/cm3. These results well demonstrate a great potential for applications of GN/AC/MnO2 composite electrodes in flexible energy storage devices.

Automated multi-filtration cleanup with nitrogen-enriched activated carbon material as pesticide multi-residue analysis method in representative crop commodities.

An automated multi-filtration cleanup (Auto m-FC) method with nitrogen-enriched activated carbon material based on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. It was applied to pesticide multi-residue analysis in six representative crop commodities. The automatic device was aimed to improve the cleanup efficiency and reduce manual operation workload in cleanup step. By controlling extracts volume, flow rate and Auto m-FC cycles, the device could finish cleanup process accurately. In this work, nitrogen-enriched activated carbon mixed with alternative sorbents and anhydrous magnesium sulfate (MgSO4) was packed in a column for Auto m-FC and followed by liquid chromatography with tandem mass spectrometric (LC-MS/MS) detection. This newly developed carbon material showed excellent cleanup performance. It was validated by analyzing 23 pesticides in six representative matrices spiked at two concentration levels of 10 and 100µg/kg. Water addition volume, salts, sorbents, Auto m-FC procedure including the flow rate and the Auto m-FC cycles for each matrix were optimized. Then, three general Auto m-FC methods were introduced to high water content, high oil and starch content, difficult commodities. Spike recoveries were within 82 and 106% and 1-14% RSD for all analytes in the tested matrices. Matrix-matched calibrations were performed with the coefficients of determination over 0.997 between concentration levels of 10 and 1000µg/kg. The developed method was successfully applied to the determination of pesticide residues in market samples.

[The influence of reference data noise on the NIR prediction results].

This article used hemicelluloses content in acacia spp. wood as a case study to demonstrate the influence of noise in the reference data on the results of NIR calibration model. The results indicated that the accuracy of NIR calibration model was affected by the reference data noise. The less noisy data was used in calibration model, the better result could be obtained. But when the noise was larger, NIR calibration model which was built by using regression mathematics methods can perform better than using primary reference data.

Influence of polymorphism of glutathione S-transferase T1 on Chinese infertile patients with varicocele.

To investigate the influence of glutathione S-transferase T1 (GSTT1) gene polymorphism on Chinese infertile patients with varicocele, 63 infertile patients with varicocele and 54 healthy fertile controls were recruited in this case-control study. Our results show that oxidative damage may be the cause of infertility in patients with varicocele, and GSTT1 null genotype predisposes to over oxidative damage to spermatocytes of infertile patients with varicocele.