Copper and Zirconium Codoped O3-Type Sodium Iron and Manganese Oxide as the Cobalt/Nickel-Free High-Capacity and Air-Stable Cathode for Sodium-Ion Batteries.

Considering the abundance of iron and manganese within the Earth's crust, the cathode O3-NaFe0.5Mn0.5O2 has shown great potential for large-scale energy storage. Following the strategy of introducing specific heteroelements to optimize the structural stability for energy storage, the work has obtained an O3-type NaFe0.4Mn0.49Cu0.1Zr0.01O2 that exhibits enhanced electrochemical performance and air stability. It displays an initial reversible capacity of 147.5 mAh g-1 at 0.1C between 2 and 4.1 V, a capacity retention ratio exceeding 69.6% after 100 cycles at 0.2C, and a discharge capacity of 70.8 mAh g-1 at a high rate of 5C, which is superior to that of O3-NaFe0.5Mn0.5O2. The codoping of Cu/Zr reserves the layered O3 structure and enlarges the interlayer spacing, promoting the diffusion of Na+. In addition, the structural stability and air stability observed by Cu-doping is well maintained via the incorporation of extra Zr favoring a highly reversible phase conversion process. Thus, this work has demonstrated an efficient strategy for developing cobalt/nickel-free high-capacity and air-stable cathodes for sodium-ion batteries.

The critical role of titanium cation in the enhanced performance of P2-Na0.5Ni0.25Mn0.60Ti0.15O2 cathode material for sodium-ion batteries.

Tremendous effort has been devoted to develop durable electrode materials for sodium ion batteries. This work focuses on enhancing the reversibility of a cathode material Na0.5Ni0.25Mn0.75O2 by adopting the titanium cation doping strategy. The obtained P2-Na0.5Ni0.25Mn0.60Ti0.15O2 material shows smooth charge-discharge curves upon suppressing the Na+/vacancy ordering effect via the partial substitution of Mn4+ for Ti4+, and enhanced cycling performance. It exhibits a reversible capacity of 138 mA h g-1 at 0.5C, as well as a high rate capacity of 81 mA h g-1 at 5C between a cut-off voltage of 2 and 4 V, while long-term cycling stability is demonstrated with a capacity retention of 84% over 200 cycles. An enhanced cycling stability is also observed when the voltage is between 2 and 4.2 V. The feasibility of constructing a symmetrical Na-ion full cell with Na0.5Ni0.25Mn0.60Ti0.15O2 as cathode and anode electrodes is also demonstrated. The titanium cation doping results in reduced charge transfer impedance and an enhanced sodium cation diffusion coefficient, thus suggesting an efficient strategy to obtain a durable cathode material for sodium ion batteries.

Low-Strain Reticular Sodium Manganese Oxide as an Ultrastable Cathode for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are recognized as attractive alternatives for grid-scale electrochemical energy storage applications. Transition metal oxide cathodes represent one of the most dynamic materials for industrialization among the various cathodes for SIBs. Here, a cation-doped cathode Na0.44Mn0.89Ti0.11O2 with a tunnel structure is introduced, which undergoes a lowered volume change of only 5.26% during the Na+ insertion/extraction process. Moreover, the average Na+ diffusion coefficients are enhanced by more than 3-fold upon the doping of the Ti cation. The obtained cathode delivers a practically usable capacity of 119 mAh g-1 at 0.1 C as well as an enhanced discharge capacity of 96 mAh g-1 at 5 C. Durability is demonstrated by the retained 71 mAh g-1 after 1000 cycles, corresponding to a capacity retention of 74%. This work demonstrates that the reticular Na0.44Mn0.89Ti0.11O2 is a promising ultrastable cathode material for the development of long-life sodium-ion batteries.

[Effect of application of herbal medicine paste to "Tianshu" (ST25)on intestinal mobility and expression of vasoactive intestinal peptide and substance P in colonic myenteric plexus in rats with functional constipation].

OBJECTIVE: To observe the effect of acupoint application at bilateral "Tianshu" (ST25) on intestinal mobility and immunoactivity of vasoactive intestinal peptide (VIP) and substance P (SP) in colonic myenteric plexus of rats with functional constipation (FC), so as to analyze its mechanisms underlying improving FC. METHODS: Forty male SD rats were randomly divided into 4 groups, namely normal control, model, acupoint application and medication, with 10 rats in each group. The FC model was established by gavage of Loperamide Hydrochloride suspension fluid (0.5 mg/mL, 3 mg·kg-1·d-1) for 7 days. Herbal medicine paste (composed of Rheum Officinale, Sodium Sulfate, Mangnolia Officinalis, etc.) was applied to bilateral ST25 for 6 h, once daily for 4 weeks. Rats of the medication group were treated by gavage of Mosapride suspension fluid (0.15 mg/mL, 1.58 mg·kg-1·d-1) for 4 weeks. After the treatment, the rats were deprived of water for 12 hours, and then treated by gavage of 2 mL of activated carbon suspension, followed by recording the first black defecation time and the number of fecal particles and water content of feces within 6 h so as to assess the intestinal mobility. The immunoactivity and average surface density of VIP and SP positive granules in the colonic myenteric plexus were detected by immunohistochemistry. RESULTS: Compared with the normal control group, the first black defecation time was significantly prolonged, and the number and water content of fecal particles within 6 h, and the expression and the average surface density of VIP and SP were significantly reduced in the model group (P<0.01). After the treatment and compared with the model group, the first black defecation time was shortened, and the fecal water content and fecal particle number within 6 h, as well as the expression and the average surface density of VIP and SP were considerably increased in both acupoint application and medication groups (P<0.01). There were no significant differences between the acupoint application and medication groups in all the indexes mentioned above after the interventions (P>0.05). CONCLUSION: Acupoint application may improve the intestinal motility in FC rats, which may be asso-ciated with its effects in up-regulating the immunoactivity of VIP and SP in colonic myenteric plexus of the large intestine.

A rapid and effective approach for on-site assessment of total carotenoid content in wolfberry juice during processing.

BACKGROUND: Carotenoid content analysis in wolfberry processed products has mainly focused on the determination of zeaxanthin or zeaxanthin dipalmitate, which cannot indicate the total carotenoid content (TCC) in wolfberries. RESULTS: We have exploited an effective approach for rapid extraction of carotenoid from wolfberry juice and determined TCC using UV-visible spectrophotometry. Several solvent mixtures, adsorption wavelengths of carotenoid extracts and extraction procedures were investigated. The optimal solvent mixture with broad spectrum polarity was hexane-ethanol-acetone (2:1:1) and optimal wavelength was 456 nm. There was no significant difference of TCC in wolfberry juice between direct extraction and saponification extraction. CONCLUSION: The developed method for assessment of TCC has been successfully employed in quality evaluation of wolfberry juice under different processing conditions. This measurement approach has inherent advantages (simplicity, rapidity, effectiveness) that make it appropriate for obtaining on-site information of TCC in wolfberry juice during processing.

Electrochemical determination of microRNA-21 based on bio bar code and hemin/G-quadruplet DNAenzyme.

A simple and novel microRNA (miRNA) biosensor was developed using DNA-Au bio bar code (DNA-Au) and G-quadruplex-based DNAenzyme. DNA-Au increased the amount of miRNA-21 participating in hybridization. Hemin/G-quadruplex DNAenzyme significantly improved the catalysis of H(2)O(2) by oxidation of hydroquinone, resulting in an obvious reduction current of benzoquinone for miRNA-21 indirect detection. Under optimum conditions, the linear relationship between miRNA-21 concentration and reduction response was obtained with the detection limit of 0.006 pM, which showed a good sensitivity. Besides, selectivity of the biosensor was investigated by detecting the base mismatched miRNAs. This proposed method was further applied to detect miRNA-21 extracted from human hepatocarcinoma BEL-7402 cells and human mastocarcinoma MCF-7 cells. The influence of bisphenol A (BPA) on the expression of miRNA-21 in cells was also investigated. The biosensor performs well in practical applications, which suggests it may provide a new platform for gene diagnosis.

Electrochemical determination of theophylline in foodstuff, tea and soft drinks based on urchin-like CdSe microparticles modified glassy carbon electrode.

A simply electrochemical method based on CdSe microparticles modified glassy carbon electrode (GCE) was developed to determine theophylline using cyclic voltammetry and differential pulse voltammetry. Theophylline showed a well-defined oxidation peak at the fabricated electrode in phosphate buffer solution and the oxidation peak current is much higher than that at the bare GCE, indicating that CdSe can effectively improve the oxidation of theophylline. Several effect factors on theophylline determination were optimised, such as CdSe amount, solution pH, scan rate and accumulation time. Under the optimal conditions, the oxidation peak current of theophylline was proportional to its concentration in the range of 1.0-40 and 40-700 µM with a correlation coefficient of 0.9974 and 0.9956, respectively. The limit of detection was estimated to be 0.4 µM (S/N=3). The developed method showed good reproducibility and excellent selectivity. The fabricated electrode was successfully used to determine theophylline in tea, carbonated cola drink, fruit juice drink, fermented milk drink and preserved fruit with acceptable recovery.

Multifunctional Fe3O4 core/Ni-Al layered double hydroxides shell nanospheres as labels for ultrasensitive electrochemical immunoassay of subgroup J of avian leukosis virus.

A novel electrochemical immunosensor for ultrasensitive detection of subgroup J of avian leukosis virus (ALVs-J) was designed by using graphene sheets (GS)-layered double hydroxides (LDHs) composites modified electrode with multifunctional Fe(3)O(4) core/Ni-Al LDHs shell (LDHs@Fe(3)O(4)) nanospheres as labels. At first, the GS-LDHs were used for the immunosensor platform for improving the electronic transmission rate as well as increasing the surface area to capture a large amount of primary antibodies (Ab(1)). After that, ferrocene (Fc), secondary antibodies (Ab(2)) and horseradish peroxidase (HRP) multifunctional LDHs@Fe(3)O(4) nanospheres were used as labels with high load amount and good biological activity. Subsequently, in presence of H(2)O(2), amplified signals were obtained by an electrochemical sandwich immunoassay protocol. To embody the signal amplification property of the protocol, the analytical properties of various immunosensor platform and labels were compared in detail. Under optimal conditions, the reduction peak currents of the electrochemical immunosensor were proportional to the ALVs-J concentration over the range from 10(2.32) to 10(5.50) TCID(50)/mL with a low detection limit (180 TCID(50)/mL, S/N=3). The resulting immunosensor also displayed a good selectivity, reproducibility and stability.

Electrochemical determination of microRNA-21 based on graphene, LNA integrated molecular beacon, AuNPs and biotin multifunctional bio bar codes and enzymatic assay system.

MicroRNAs (miRNAs), a kind of small, endogenous, noncoding RNAs (∼22 nucleotides), might play a crucial role in early cancer diagnose due to its abnormal expression in many solid tumors. As a result, label-free and PCR-amplification-free assay for miRNAs is of great significance. In this work, a highly sensitive biosensor for sequence specific miRNA-21 detection without miRNA-21 labeling and enrichment was constructed based on the substrate electrode of dendritic gold nanostructure (DenAu) and graphene nanosheets modified glassy carbon electrode. Sulfydryl functionalized locked nucleic acid (LNA) integrated hairpin molecule beacon (MB) probe was used as miRNA-21 capture probe. After hybridized with miRNA-21 and reported DNA loading in gold nanoparticles (AuNPs) and biotin multi-functionalized bio bar codes, streptavidin-HRP was brought to the electrode through the specific interaction with biotin to catalyze the chemical oxidation of hydroquinone by H(2)O(2) to form benzoquinone. The electrochemical reduction signal of benzoquinone was utilized to monitor the miRNA-21 hybridization event. The effect of experimental variables on the amperometric response was investigated and optimized. Based on the specific confirmation of probe and signal amplification, the biosensor showed excellent selectivity and high sensitivity with low detection limit of 0.06 pM. Successful attempts are made in miRNA-21 expression analysis of human hepatocarcinoma BEL-7402 cells and normal human hepatic L02 cells.

One-step "green" preparation of graphene nanosheets and carbon nanospheres mixture by electrolyzing graphite rob and its application for glucose biosensing.

The graphene nanosheets and carbon nanospheres mixture (GNS-CNS) was prepared by electrolyzing graphite rob in KNO(3) solution under constant current, which was characterized by TEM, AFM, SEM, FT-IR, XRD, XPS, TGA and UV-vis. The nano-mixture can keep stable in water for more than one month. Based on this kind of mixture material, a novel electrochemical biosensing platform for glucose determination was developed. Cyclic voltammetry of glucose oxidase (GOD) immobilized on GNS-CNS/GCE exhibited a pair of well-defined quasi-reversible redox peaks at -0.488 V (E(pa)) and -0.509 V (E(pc)) by direct electron transfer between the protein and the electrode. The charge-transfer coefficient (α) was 0.51, the electron transfer rate constant was 2.64 s(-1) and the surface coverage of HRP was 3.18×10(-10) mol cm(-2). The immobilized GOD could retain its bioactivity and catalyze the reduction of dissolved oxygen. The glucose biosensor has a linear range from 0.4 to 20 mM with detection limit of 0.1 mM. Moreover, the biosensor exhibits acceptable reproducibility and storage stability. The fabricated biosensor was further used to determine glucose in human plasma sample with the recoveries from 96.83% to 105.52%. Therefore, GOD/GNS-CNS/GCE could be promisingly applied to determine blood sugar concentration in the practical clinical analysis.

Electrochemical behaviour of Sudan I at Fe3O4 nanoparticles modified glassy carbon electrode and its determination in food samples.

In this work, a simple and sensitive electrochemical method was developed to determine Sudan I based on magnetic Fe3O4 nanoparticles modified glassy carbon electrode using cyclic voltammetry and differential pulse voltammetry. The sensor exhibited an obviously electrocatalytic activity towards the oxidation of Sudan I, which can be confirmed by the increased oxidation peak current and the decreased oxidation peak potential when compared with the bare GCE. The determination conditions, such as pH, modifier amount, accumulation time and accumulation potential, were optimised. And some kinetic parameters were calculated. Under the optimum experimental conditions, the oxidation current of Sudan I was proportional to its concentration from 0.01 to 1µM and 1 to 20µM. The detection limit was estimated to be 0.001µM (S/N=3). The developed method was successfully applied to determine Sudan I content in food samples with satisfactory results.