Carbon Corrosion Induced by Surface Defects Accelerates Degradation of Platinum/Graphene Catalysts in Oxygen Reduction Reaction.

Graphene supported electrocatalysts have demonstrated remarkable catalytic performance for oxygen reduction reaction (ORR). However, their durability and cycling performance are greatly limited by Oswald ripening of platinum (Pt) and graphene support corrosion. Moreover, comprehensive studies on the mechanisms of catalysts degradation under 0.6-1.6 V versus RHE (Reversible Hydrogen Electrode) is still lacking. Herein, degradation mechanisms triggered by different defects on graphene supports are investigated by two cycling protocols. In the start-up/shutdown cycling (1.0-1.6 V vs. RHE), carbon oxidation reaction (COR) leads to shedding or swarm-like aggregation of Pt nanoparticles (NPs). Theoretical simulation results show that the expansion of vacancy defects promotes reaction kinetics of the decisive step in COR, reducing its reaction overpotential. While under the load cycling (0.6-1.0 V vs. RHE), oxygen containing defects lead to an elevated content of Pt in its oxidation state which intensifies Oswald ripening of Pt. The presence of vacancy defects can enhance the transfer of electrons from graphene to the Pt surface, reducing the d-band center of Pt and making it more difficult for the oxidation state of platinum to form in the cycling. This work will provide comprehensive understanding on Pt/Graphene catalysts degradation mechanisms.

Regulating the Pore Structure of Activated Carbon by Pitch for High-Performance Sodium-Ion Storage.

The pore structure of carbon anodes plays a crucial role in enhancing the sodium storage capacity. Designing more confined pores in carbon anodes is accepted as an effective strategy. However, current design strategies for confined pores in carbon anodes fail to achieve both high capacity and initial Coulombic efficiency (ICE) simultaneously. Herein, we develop a strategy for utilizing the repeated impregnation and precarbonization method of liquid pitch to regulate the pore structure of the activated carbon (AC) material. Driven by capillary coalescence, the pitch is impregnated into the pores of AC, which reduces the specific surface area of the material. During the carbonization process, numerous pores with diameters less than 1 nm are formed, resulting in a high capacity and improved ICE of the carbon anode. Moreover, the ordered carbon layers derived from the liquid pitch also enhance the electrical conductivity, thereby improving the rate capability of as-obtained carbon anodes. This enables the fabricated material (XA-4T-1300) to have a high ICE of 91.1% and a capacity of 383.0 mA h g-1 at 30 mA g-1. The capacity retention is 95.5% after 300 cycles at 1 A g-1. This study proposes a practical approach to adjust the microcrystalline and pore structures to enhance the performance of sodium-ion storage in materials.

Constructing Ni12P5/Ni2P Heterostructures to Boost Interfacial Polarization for Enhanced Microwave Absorption Performance.

Heterostructures with a rich phase boundary are attractive for surface-mediated microwave absorption (MA) materials. However, understanding the MA mechanisms behind the heterogeneous interface remains a challenge. Herein, a phosphine (PH3) vapor-assisted phase and structure engineering strategy was proposed to construct three-dimensional (3D) porous Ni12P5/Ni2P heterostructures as microwave absorbers and explore the role of the heterointerface in MA performance. The results indicated that the heterogeneous interface between Ni12P5 and Ni2P not only creates sufficient lattice defects for inducing dipolar polarization but also triggers uneven spatial charge distribution for enhancing interface polarization. Furthermore, the porous structure and proper component could provide an abundant heterogeneous interface to strengthen the above polarization relaxation process, thereby greatly optimizing the electromagnetic parameters and improving the MA performance. Profited by 3D porous heterostructure design, P400 could achieve the maximum reflection loss of -50.06 dB and an absorption bandwidth of 3.30 GHz with an ultrathin thickness of 1.20 mm. Furthermore, simulation results confirmed its superior ability (14.97 dB m2 at 90°) to reduce the radar cross section in practical applications. This finding may shed light on the understanding and design of advanced heterogeneous MA materials.

Prospects and Problems for Identification of Poisonous Plants in China using DNA Barcodes.

OBJECTIVE: Poisonous plants are a deadly threat to public health in China. The traditional clinical diagnosis of the toxic plants is inefficient, fallible, and dependent upon experts. In this study, we tested the performance of DNA barcodes for identification of the most threatening poisonous plants in China. METHODS: Seventy-four accessions of 27 toxic plant species in 22 genera and 17 families were sampled and three DNA barcodes (matK, rbcL, and ITS) were amplified, sequenced and tested. Three methods, Blast, pairwise global alignment (PWG) distance, and Tree-Building were tested for discrimination power. RESULTS: The primer universality of all the three markers was high. Except in the case of ITS for Hemerocallis minor, the three barcodes were successfully generated from all the selected species. Among the three methods applied, Blast showed the lowest discrimination rate, whereas PWG Distance and Tree-Building methods were equally effective. The ITS barcode showed highest discrimination rates using the PWG Distance and Tree-Building methods. When the barcodes were combined, discrimination rates were increased for the Blast method. CONCLUSION: DNA barcoding technique provides us a fast tool for clinical identification of poisonous plants in China. We suggest matK, rbcL, ITS used in combination as DNA barcodes for authentication of poisonous plants.

[Evaluation of the capacity of personal protection on poison emergency items in Chinese disease control and prevention institutes].

OBJECTIVE: To analyze the capacity of personal protection on poison emergency items in Chinese disease control and prevention institutes. METHODS: Evaluation analysis based on data obtained from investigating personal protection equipments and professional knowledge quizzing about personal protection in poisoning control of 57 different level centers for disease control and prevention selected from China by a multi-stage stratified sampling. RESULTS: All 80.70% of the institutes possessed the protection equipments, provincial, municipal, county level institutes were 100.00%, 95.24%, 66.67%, respectively, with significant statistical difference (H = 7.94, P < 0.05). The average level of the type of individual protective equipments in disease control and prevention institutes was (5.42 +/- 4.00) kinds, the average points in category of provincial, municipal, county level institutes were (11.33 +/- 3.67), (6.52 +/- 3.16), (3.47 +/- 3.10) kinds, being statistically significant (F = 17.30, P < 0.05); type difference counts of disease control and prevention institutes in economic development, secondary, less-developed regions were (6.41 +/- 4.03), (3.55 +/- 3.35), (6.45 +/- 4.07) kinds, with statistical significance (F = 3.70, P < 0.05). Protection equipments chiefly possessed were latex gloves, gauze masks and C-protective clothing. Protective clothing and respiratory protective equipments were insufficient evidently. The average points in testing personal protection basic knowledge were (71.39 +/- 12.52) points; there were no differences between different institutes with different economic regions, levels, technical posts and title degrees. CONCLUSION: Certain advances have been achieved in recent years in personal protection capacity of institutes for disease control and prevention, but far from the actual demands, and maybe no enough effective response on emergency occurred.

[Development and application of poison databank and poisonous animal and plants sample databank].

OBJECTIVE: To establish a comprehensive,easily approached, operated, and searched internet poison databank as to providing professional poison data and knowledge of effective treatment for those consented such as medical staff, and emergency response team in the shortest time. METHODS: We established a computer poison databank, by adopting B/S structure, using SQL Server databank, and explore technology, in which all information may easily be explored and obtained by users. RESULTS: The database integrated the information in relating to the substances identifiers, physical and chemical properties, toxicology data, clinical manifestation while intoxication, emergency response guides, effective treatment, anything related to the special antidotes, preventive measures, poison analysis, and manufacturers of chemicals, pharmaceuticals, herbs, pesticides, animal, plant, bacteria, fungi, productions and toxins. Otherwise some information about poison control organizations and experts, literatures about poison case reports, poison incidents, were also involved in the system, which can also provide a shortcut, convenient, and exact search. CONCLUSIONS: The databank might be easily used on several fields, providing important information with acute poison incidents disposal and clinic treatment.

Multiple biomarkers response in maize (Zea mays L.) during exposure to copper.

Biomarkers in higher plants played an important role to estimate exposure effects of pollutants in soil ecosystem and have received increasing attention in recent years. The qualitative and quantitative modifications arising in amplified fragment length polymorphism (AFLP) profiles as a measure of DNA effects were compared with a number of parameters, namely, the root length, total soluble protein content in root tips, chlorophylls content and shoot size to select the most sensitive biomarker responding to copper stress in the range of 0-600 mg/kg. The changes occurring in AFLP profiles of root tips following Cu treatment included loss of normal bands and appearance of new bands and variation in band intensity in comparison to that of the normal seedlings. A reduction in root length was observed at the 200 mg/kg of copper, which was accompanied with a decrease in total soluble protein content. According to their sensitivity to the copper toxicity, the above indicator rank in the following order: AFLP profiles > total soluble protein content > root length > chlorophylls content > shoot. We concluded that the AFLP offered a useful alternative biomarker assay for the detection of genotoxic effects of environmental pollutants.