Xanthones with multiple roles against diabetes: their synthesis, structure-activity relationship, and mechanism studies.

A four-step synthetic process has been developed to prepare 1,3,5,8-tetrahydroxyxanthone (2a) and its isomer 1,3,7,8-tetrahydroxyxanthone (2b). 25 more xanthones were also synthesized by a modified scheme. Xanthone 2a was identified as the most active inhibitor against both α-glucosidase and aldose reductase (ALR2), with IC50 values of 7.8 ± 0.5 µM and 63.2 ± 0.6 nM, respectively, which was far active than acarbose (35.0 ± 0.1 µM), and a little more active than epalrestat (67.0 ± 3.0 nM). 2a was also confirmed as the most active antioxidant in vitro with EC50 value of 8.9 ± 0.1 µM. Any structural modification including methylation, deletion, and position change of hydroxyl group in 2a will cause an activity loss in inhibitory and antioxidation. By applying a H2 O2 -induced oxidative stress nematode model, it was confirmed that xanthone 2a can be absorbed by Caenorhabditis elegans and is bioavailable to attenuate in vivo oxidative stress, including the effects on lifespan, superoxide dismutase, Catalase, and malondialdehyde. 2a was verified with in vivo hypoglycemic effect and mitigation of embryo malformations in high glucose. All our data support that xanthone 2a behaves triple roles and is a potential agent to treat diabetic mellitus, gestational diabetes mellitus, and diabetic complications.

An Improved Weighted and Location-Based Clustering Scheme for Flying Ad Hoc Networks.

Flying ad hoc networks (FANETs) have been gradually deployed in diverse application scenarios, ranging from civilian to military. However, the high-speed mobility of unmanned aerial vehicles (UAVs) and dynamically changing topology has led to critical challenges for the stability of communications in FANETs. To overcome the technical challenges, an Improved Weighted and Location-based Clustering (IWLC) scheme is proposed for FANET performance enhancement, under the constraints of network resources. Specifically, a location-based K-means++ clustering algorithm is first developed to set up the initial UAV clusters. Subsequently, a weighted summation-based cluster head selection algorithm is proposed. In the algorithm, the remaining energy ratio, adaptive node degree, relative mobility, and average distance are adopted as the selection criteria, considering the influence of different physical factors. Moreover, an efficient cluster maintenance algorithm is proposed to keep updating the UAV clusters. The simulation results indicate that the proposed IWLC scheme significantly enhances the performance of the packet delivery ratio, network lifetime, cluster head changing ratio, and energy consumption, compared to the benchmark clustering methods in the literature.

Update on techniques for cryopreservation of human spermatozoa.

In the 1960s, sperm cryopreservation was developed as a method to preserve fertility. Currently, techniques for the cryopreservation of human spermatozoa have been widely used in assisted reproduction. However, although sperm cryobiology has made notable achievements, the optimal method for the recovery of viable spermatozoa after cryopreservation remains elusive. Postthawing sperm quality can be affected by cryoprotectants, ice formation, storage conditions, and osmotic stress during the freezing process. This review discusses recent advances in different cryopreservation techniques, cryoprotectants, and freezing and thawing methods during cryopreservation and new indications for the use of cryopreserved spermatozoa.

Novel hierarchical Sn3O4/BiOX (X = Cl, Br, I) p-n heterostructures with enhanced photocatalytic activity under simulated solar light irradiation.

Sn3O4/BiOX (X = Cl, Br, I), a series of p-n-heterojunction-based photocatalysts, were prepared by a combination of an ultrasonic-assisted precipitation-deposition method and hydrothermal method. The photodegradation of Rhodamine B among all the materials, under simulated solar light irradiation, was investigated in detail. The photocatalyst test showed that the novel composite, Sn3O4/BiOCl, was able to degrade 99% of Rhodamine B (RhB) and its intermediates in 9 minutes, which is faster than Sn3O4/BiOBr (21 min) and Sn3O4/BiOI (12 min). Moreover, the degradation rate of RhB for Sn3O4/BiOCl samples (Sn : Bi = 1/4) was the highest, about 99%, slightly higher than that of Sn3O4/BiOCl-1/8 (95%), which was significantly higher than those of Sn3O4/BiOCl-1/2 (78%), BiOCl (77%), P25 (62%) and Sn3O4 (16%) after nine minutes of irradiation under a xenon lamp. It can be inferred that when the bismuth/tin ratio was optimum, BiOCl enabled the formation of the enough space charge regions on the surface of Sn3O4, which promoted the separation of photogenerated electron-hole pairs. This implied that high-quality interfaces in the heterostructure catalysts play a key role in improving the photocatalytic performance. The enhanced photocatalytic performance can be attributed to the synergistic effects from two main factors: (1) the layered multi-stage structure increases the scattering of light on the catalyst surface, which proves to be beneficial in enhancing the absorption of the visible light; (2) the p-n heterojunctions between Sn3O4 and BiOX (X = Cl, Br, I) efficiently promote the separation of photogenerated carriers and accelerate the migration of photogenerated carriers. In addition, the results of the 'active species trapping' experiment illustrated that in the Sn3O4/BiOCl composite, holes contribute more to the high photocatalytic performance, while hydroxyl radicals show less importance to degrade RhB. Moreover, the photocatalytic mechanism was also discussed based on the investigation of reactive species and the band structure of Sn3O4/BiOCl.

Electrochemical Properties of Controlled Size Mn3O4 Nanoparticles for Supercapacitor Applications.

A simple and controlled strategy has been used to synthesise Mn3O4 nanoparticles (NPs) via hydrothermal method. The Mn3O4 nanoparticles were further applied for supercapacitor electrode materials. The unique squared-shape Mn3O4 nanoparticles exhibited excellent electrochemical performance due to the small size and porous architecture. After electrochemical testing, the Mn3O4 NPs based electrode showed a large specific capacitance (380 F g-1, 1.0 mAcm-2) and good cycling stability (88.6%) of the initial capacitance after 5000 cycles in 1.0 M Na2SO4 solution. These results may provide useful guidelines for materials selection, synthesis, size and configuration designs for the novel energy storage devices based on transitional metal oxides.

Enhanced UV-Visible Light Photocatalytic Activity by Constructing Appropriate Heterostructures between Mesopore TiO2 Nanospheres and Sn3O4 Nanoparticles.

Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping photoluminescence experiments under ultraviolet (UV) and visible light irradiation, respectively. Especially under the visible light, the TiO2/Sn3O4 nanocomposites demonstrated a superb photocatalytic activity, with 81.2% of methyl orange (MO) decomposed at 30 min after irradiation, which greatly exceeded that of the P25 (13.4%), TiO2 (0.5%) and pure Sn3O4 (59.1%) nanostructures. This enhanced photocatalytic performance could be attributed to the mesopore induced by the monodispersed TiO2 cores that supply sufficient surface areas and accessibility to reactant molecules. This exquisite hetero-architecture facilitates extended UV-visible absorption and efficient photoexcited charge carrier separation.

Effects of circuit residual volume salvage reinfusion on the postoperative clinical outcome for pediatric patients undergoing cardiac surgery.

This study aimed to evaluate the effects of washed cardiopulmonary (CPB) circuit residual blood reinfusion on the postoperative clinical outcome for pediatric patients undergoing cardiac surgery. A total of 309 consecutive Chinese cardiac patients receiving CPB between October 2010 and April 2011 were prospectively analyzed. For 217 patients, CPB circuit residual blood was reinfused after the cell-saving procedure [cell-salvage group (CS)]. The remaining 92 patients were directly transfused with allogenic red blood cells (RBCs) after their operation [control group (CON)]. Assessment included perioperative transfusion of RBCs, postoperative hematocrit (HCT), chest tube drainage during the first 24 h after the operation, intrahospital mortality, respiratory morbidity, and renal dysfunction. The two groups were well matched in terms of demographics, CPB data, and complexity of surgical procedure. The patients in the CS group had a significantly higher HCT level postoperatively (p = 0.018) and a less allogenic RBCs transfusion (p = 0.000). The two groups did not differ in terms of chest tube drainage during the first 24 h postoperatively, intrahospital mortality, or respiratory morbidity. The incidence of serum creatinine (≥ 2-folds) during the first 72 h after the operation was significantly lower in the CS group (2.3 %) than in the CON group (8.7 %) (p = 0.010). Reinfusion of washed CPB circuit residual blood significantly raised the postoperative HCT level, reduced the allogeneic blood transfusion, decreased the incidence of early postoperative renal dysfunction, and did not increase the chest tube drainage after the operation in pediatric cardiac surgery.