Size-Controlled Boron-Based Bifunctional Photocathodes for High-Efficiency Photo-Assisted Li-O2 Batteries.

Photo-assisted Li-O2 batteries are introduced as a promising strategy for reducing severe overpotential by directly employing photocathodes. Herein, a series of size-controlled single-element boron photocatalysts are prepared by the meticulous liquid phase thinning methods by combining probe and water bath sonication, and their bifunctional photocathodes in the photo-assisted Li-O2 batteries are systematically investigated. The boron-based Li-O2 batteries have shown incremental round-trip efficiencies as the sized reduction of boron under illumination. It is noteworthy that the completely amorphous boron nanosheets (B4 ) photocathode not only delivers an optimizing round-trip efficiency of 190% on the basis of the ultra-high discharge voltage (3.55 V) and ultra-low charge voltage (1.87 V) but also gives a high rate performance and ultralong durability with a round-trip efficiency of 133% after 100 cycles (200 h) compared with the other-sized boron photocathodes. This remarkable photoelectric performance of the B4 sample can be attracted to the synergistic effect on the suitable semiconductor property, high conductivity, and strengthened catalytic ability of boron nanosheets coated with ultrathin amorphous boron-oxides overlayer. This research can open a new avenue to facilitate the rapid development of high-efficiency photo-assisted Li-O2 batteries.

All-solid-state Ti3C2Tx neutral symmetric fiber supercapacitors with high energy density and wide temperature range.

All-solid-state Ti3C2Tx neutral symmetric fiber supercapacitors (PVA EGHG Ti3C2Tx FSCs) with high energy density and wide temperature range are constructed by using polyvinyl alcohol (PVA)-ethylene glycol hydrogel (EGHG)-sodium perchlorate (NaClO4) as electrolyte and separator, and Ti3C2Tx fiber as electrodes. Ti3C2Tx fiber is prepared using 130 mg mL-1 Ti3C2Tx nanosheet ink as an assembly unit in a coagulation bath of isopropyl alcohol (IPA) and distilled water with 5 wt% CaCl2 by a wet spinning method. The prepared Ti3C2Tx fiber exhibits a specific capacity of 385 F cm-3 and a capacitance retention of 94 % after 10,000 cycles in 1 M NaClO4 electrolyte. The assembled PVA EGHG Ti3C2Tx FSCs deliver a specific capacitance of 41 F cm-3, a volumetric energy density of 5 mWh cm-3, and a capacitance retention of 92 % after 500 times continuous bending. Furthermore, it shows good flexibility and excellent capacitance over a wide temperature range of -40 to 40 °C and maintains its electrochemical performance under varying degrees of bending. This study provides a viable strategy for designing and assembling all-solid-state neutral symmetric fiber supercapacitors with high energy density and wide temperature range.

Bifunctional Photoassisted Li-O2 Battery with Ultrahigh Rate-Cycling Performance Based on Siloxene Size Regulation.

Directly integrating the bifunctional photoelectrode into Li-O2 batteries has been considered an effective way to reduce the overpotential and promote electric energy saving. However, more regular investigations on various bifunctional photocatalysts have still been desired for high-performance photoassisted Li-O2 batteries. Herein, a systematic exploration of various-sized siloxene photocatalysts affected by Li-O2 batteries has been introduced. Compared with the utilization of larger-sized siloxene nanosheets (SNSs), the photoassisted Li-O2 battery with a siloxene quantum dot (SQD) photoelectrode delivers a superior round-trip efficiency of 230% based on the highest discharge potential up to 3.72 V and lowest charge potential of 1.60 V and enables the maintenance of a long-term cycling life with only 13% efficiency attenuation after 200 cycles at 0.075 mA/cm2. Furthermore, this system exhibits a record-high rate-cycling performance (162% round-trip efficiency, even at 3 mA/cm2) and a high discharge capacity of 2212 mAh/g at 1 mA/cm2. These ground-breaking performances could be attributed to the synergistic effect of the photocatalytic and electrocatalytic activities of SQD photocatalysts with the ideal conduction band/valence band values, the abundant defective sites, and the stronger O2 and lower LiO2 adsorption strengths of SQD photocatalysts. These systematic research studies highlight the significance of SQD bifunctional photocatalysts and could be extended to other photocatalysts for further high-efficiency photoelectric conversion and storage.

Highly sensitive soft optical fiber tactile sensor.

A soft highly sensitive tactile sensor based on an in-fiber interferometer embedded in polydimethylsiloxane (PDMS) structure is studied. Theoretical simulation obtains that the high order sensing modes and PDMS can improve the sensitivity. Experiments show that different order sensing modes, derived by fast Fourier transform (FFT) and inverse FFT methods, present different sensing performance. Corresponding to high order mode, 1.3593 nm/kPa sensitivity and 37 Pa (0.015 N) detection limit is obtained. Meanwhile, it also shows very good stability, reproducibility, and response time. This study not only demonstrates a tactile sensor with high sensitivity but also provides a novel sensing modes analysis method.

Few-layer Mg-deficient borophene nanosheets: I2 oxidation and ultrasonic delamination from MgB2.

By using I2 as an oxidant and CH3CN as a reaction medium, few-layer Mg-deficient borophene nanosheets (FBN) with a stoichiometric ratio of Mg0.22B2 are prepared by oxidizing MgB2 in a mixture of CH3CN and HCl for 14 days under nitrogen protection and followed by ultrasonic delaminating in CH3CN for 2 h. The prepared FBN possess a two-dimensional flake morphology, and they show a clear interference fringe with a d-spacing of 0.251 nm corresponding to the (208) plane of rhombohedral boron. While maintaining the hexagonal boron networks of MgB2, the FBN have an average thickness of about 4.14 nm (four monolayer borophene) and a lateral dimension of 500 nm, and the maximum Mg deintercalation rate can reach 78%. The acidity of the reaction system plays an important role; the HCl reaction system not only facilitates the oxidation of MgB2 by I2, but also increases the deintercalation ratio of Mg atoms. Etching of the Mg atom layer with HCl, the negative charge decrease of the boron layer by I2 oxidation, and the Mg chelating effect from CH3COOH due to the hydrolysis of CH3CN in an HCl environment led to a high deintercalation rate of the Mg atom. Density functional theory (DFT) calculations further support the result that the maximum deintercalation rate of Mg atoms is about 78% while maintaining the hexagonal layer structure of boron. This research solves the problems of low Mg atom deintercalation rate and hexagonal boron structure destruction when using the precursor MgB2 to produce borophene nanosheets, which is of great significance for large-scale novel preparation and application of borophene nanosheets.

Ultrahigh-energy sodium ion capacitors enabled by the enhanced intercalation pseudocapacitance of self-standing Ti2Nb2O9/CNF anodes.

In order to increase the capacity and improve the sluggish Na+-reaction kinetics of anodes as sodium ion capacitors (SICs), a Ti2Nb2O9/CNF self-standing film electrode comprised of Ti2Nb2O9 nanosheets and carbon nanofibers has been fabricated via electrospinning HTiNbO5 nanosheets with PAN and subsequent carbonization treatment. The as-prepared Ti2Nb2O9/CNF film electrode possesses fast Na-ion intercalation kinetics and high conductivity during Na-ion storage, and it displays a high reversible capacity of 324 mA h g-1 at 0.1 A g-1. Additionally, it also delivers a superior rate capability of 204 mA h g-1 at a high current density of 4 A g-1, as well as an excellent cycling stability of 97% retention after 2000 cycles at 1 A g-1 in a half-cell test. A prototype Ti2Nb2O9/CNF//AC SIC full device was assembled by employing the presodiated Ti2Nb2O9/CNF anode and AC cathode, and it exhibits an high energy density of 129 W h kg-1 at a power density of 75 W kg-1 and a high power density (7560 W kg-1 with 63 W h kg-1), a good cycling performance of 85% capacitance retention after 10 000 cycles at 1 A g-1, suggesting that the Ti2Nb2O9/CNF electrode with excellent performance would be a very promising candidate as the anode for high-performance SICs.

Ultra-Large Sized Siloxene Nanosheets as Bifunctional Photocatalyst for a Li-O2 Battery with Superior Round-Trip Efficiency and Extra-Long Durability.

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O2 batteries. Herein, a novel bifunctional photo-assisted Li-O2 system is constructed by using siloxene nanosheets with ultra-large size and few-layers due to its superior light harvesting, semiconductor characteristic, and low recombination rate. An ultra-low charge potential of 1.90 V and ultra-high discharge of 3.51 V have been obtained due to the introduction of this bifunctional photocatalyst into Li-O2 batteries, and these results have realized the round-trip efficiency up to 185 %. In addition, this photo-assisted Li-O2 batteries exhibits a high rate (129 % round-trip efficiency at 1 mA cm-2 ), a prolonged cycling life with 92 % efficiency retention after 100 cycles, and the highly reversible capacity of 1170 mAh g-1 at 0.75 mA cm-2 . This work will open the vigorous opportunity for high-efficiency utilization of solar energy into electric system.

Electrospun Nb2O5 nanorods/microporous multichannel carbon nanofiber film anode for Na+ ion capacitors with good performance.

For the disadvantages of both the slow reaction kinetics and the poor conductivity for Nb2O5 electrode materials as sodium-ion capacitors (SICs), Nb2O5 NRs/NMMCNF film electrode with good flexibility and high electrochemical property has been fabricated by electrospinning PAN/PMMA/H2Nb2O6·H2O homogeneous viscous suspension and followed by an annealing treatment, in which the precursor H2Nb2O6·H2O nanorods are obtained by grinding H2Nb2O6·H2O nanowires, and Nb2O5 nanorods are uniformly embedded in nitrogen doped microporous multichannel carbon nanofiber. Benefiting from the multichannel network structure, Nb2O5 NRs/NMMCNF film electrode delivers the fast kinetics of Na+-storage and the superior Na-ion storage performance, it delivers outstanding rate capability (101 mAh g-1 at 4 A g-1) and ultralong lifespan (91% capacity retention after 10,000 cycles at 2 A g-1). A Nb2O5 NRs/NMMCNF//AC SIC based on the Nb2O5 NRs@NMMCNF fiber film anode and the AC cathode is assembled. The energy density of the as-assembled device is as high as 91 Wh kg-1 and its maximum power density is 7499 W kg-1. This work offers a new structure design strategy toward intercalation-type metal oxide electrodes for application in SICs.

Few-layer and large flake size borophene: preparation with solvothermal-assisted liquid phase exfoliation.

The preparation of two-dimensional boron (B) nanosheets, especially for borophene, is still a challenge because of its unique structure and complex B-B bonds in bulk boron. In the present work, a novel preparation technology for borophene with only a few layers and large flake sizes is developed by a solvothermal-assisted liquid phase exfoliation process, consisting of ball milling-thinning, solvothermal swelling, and probe ultrasonic delamination. The exfoliation effect of the bulk B precursors is related to the surface tension and Hildebrand parameter of the selected solvents such as acetone, N,N-dimethyl formamide (DMF), acetonitrile, ethanol, and N-methyl pyrrolidone (NMP), and a relative small surface tension when using solvents is favorable for the exfoliation of bulk B. Four-layer thick borophene and an average lateral size of 5.05 µm can be obtained in acetone as the exfoliating solvent. The surface composition of the exfoliated few-layer borophene with large flake size hardly changes, while the chemical state of B changes to some extent because they are partly oxidized on the surface by contaminates before and after exfoliation. This acetone solvothermal-assisted liquid phase exfoliation technique can be used to prepare high quality borophene with large horizontal sizes, and it will provide the basis to study few-layer borophene with large sizes further.

[Investigation of intestinal nematode infections in Hongze County, Jiangsu Province].

OBJECTIVE: To understand the situation of intestinal nematode infections and assess the preventive effects, so as to provide the evidence for formulating the further measures of prevention. METHODS: Five villages from 5 townships of different geographical locations were selected and 500 residents of each village were surveyed. The eggs of intestinal nematodes were detected by the Kato-Katz technique, and 50 students and 50 residents per village were investigated by questionnaires about health education. RESULTS: Among 3 011 people detected, 17 persons were infected with intestinal nematodes and the total infection rate was 0.56%. The rates of Ascaris lumbricoides, hookworm, Trichuris trichiura, Enterobius vermicularis, and Trichostrongylus were 0.10%, 0.33%, 0.03%, 0.03% and 0.07%, respectively. The awareness rate of health knowledge was 97.80% and the formation rate of health behavior was 97.00%. CONCLUSION: The infection rates of intestinal nematodes, the awareness rate of health knowledge and the formation rate of health behavior in the population of Hongze County have achieved the criteria of effective control of intestinal parasitic diseases.

[Analysis of malaria situation and discussion of control strategies in Huai'an City, 2014].

OBJECTIVE: To understand the malaria epidemic situation in Huai'an City in 2014, so as to provide the evidence for formulating and adjusting effective strategies and measures to eliminate malaria. METHODS: The reported malaria cases from the Internet Reporting System and the epidemiological data of malaria of Huai'an City in 2014 were collected and analyzed statistically. RESULTS: A total of 56 malaria cases were reported in Huai'an City in 2014 with the incidence of 0.12/10,000, and 43.59% of increasing rate compared with the previous year (39 cases). All these cases were imported from African countries. There were 50 cases of falciparum malaria, 4 cases of ovale malaria, 1 case of quartan malaria and 1 case of mixed infections. All the patients were male and aged 24-59 years. Totally 96.43% of the patients (54 cases) were peasants and 69.64% of them (39 cases) only received junior high school education. The malaria cases were mainly distributed in Huai'an District (32 cases), Xuyi County (8 cases) and Huaiyin District (6 cases), totally accounting for 82.14%. There was no significant seasonal variation in the reporting time of the cases. The median time from onset to seeing a doctor was 2 days and the median time from seeing a doctor to being diagnosed was 1 day. Totally 16.67% of the patients (8 cases) were misdiagnosed when they first visited a doctor. All the patients were laboratory confirmed and all of them received the standard treatment after diagnosis. CONCLUSIONS: There have been no local malaria cases reported from Huai'an City in the last three years. However, the situation of imported malaria is more serious and the species of infected Plasmodium are more diverse. Therefore, to accomplish the aim of malaria elimination in the whole city, it is necessary to further strengthen the multi-sectoral cooperation, health education, malaria screening and professional training to control the imported malaria.

[Cost-benefit analysis of netting cultivation to block the spread of Oncomelania snails in lake regions].

OBJECTIVE: To evaluate the cost-benefit of netting cultivation to block the spread of Oncomelania snails in lake regions. METHODS: The cost-benefit of netting cultivation was investigated by interviewing in the field, the cost of Oncomelania snail survey and control was investigated by retrospective review in Gaoyou Lake regions of Jinhu County from 2009 to 2011. The benefit of netting cultivation to block the spread of snails in lake regions was calculated by the benefit-cost ratio (BCR), and then the cost-benefit of them was calculated. RESULTS: The area of netting cultivation in Gaoyou Lake regions was 70.77 hm2, the average cost of netting cultivation was 495,595 yuan every year, the average income was 962,000 yuan every year, and the average benefit of netting cultivation was 466 405 yuan. The average cost of Oncomelania snail survey and control from 2009 to 2011 was 85,047.87 yuan in Gaoyou Lake regions. The ratio of cost-benefit was 1.11:1. The benefit was more than the cost. CONCLUSION: There is a well benefit in lake regions during blocking the spread of snails by netting cultivation.