Eco-friendly preparation and characterization of high-performance electrothermal graphene-AgNPs/lignocellulose composites.

Graphene-based (Gr-based) electrothermal heaters, due to their light weight, low electrical resistance, high thermal conductivity, and easy accessibility, have attracted widespread attention in the field of electrothermal heating. To achieve a high steady-state temperature in electrothermal heaters under low voltage, here we constructed a Gr-based film with low electrical resistance. Firstly, we employed non-toxic vitamin C to reduce silver nitrate for the in situ chemical deposition of silver nanoparticles (AgNPs) on the Gr surface. The SEM results confirmed that the AgNPs were uniformly deposited on the Gr surface. The synergistic interaction between AgNPs and Gr provided high-speed electrons transport paths for the film. On the other hand, we employed biodegradable lignocellulose fiber (LCF) as a dispersant and film-forming agent. The aromatic ring structure of LCF interacts with Gr via π-π interactions, aiding the dispersion of Gr in aqueous solutions. SEM results revealed that LCF permeated through the surfaces and interstices of the two-dimensional Gr sheets, providing mechanical support for the composite film. This approach enables the creation of freestanding Gr-AgNPs/LCF electrothermal composites. The resistivity and electrothermal results demonstrated that the obtained 20 wt% Gr-based composite film possessed low electrical resistance (5.4 Ω sq-1) and exhibited an outstanding saturated temperature of 214 °C under a very low input voltage of 7 V. The preparation method of this Gr-based composite film is simple, easy to operate, and environmentally friendly, providing a new reference for the preparation of eco-friendly and high-performance resistance heating electronics.

Victimization and depressive symptoms among Chinese adolescents: A moderated mediation model.

BACKGROUND: Victimization as an inducing factor of depressive symptoms has been confirmed in previous studies. However, little is known about how and when it induces depressive symptoms in adolescents. METHODS: In total, 1174 Chinese adolescents were recruited to complete the Juvenile Victimization Questionnaire, Security Questionnaire, Positive Psychological Capital Questionnaire, and the Chinese version of the Center for Epidemiologic Studies Depression Scale. RESULTS: After controlling for gender and school type, the sense of security partially mediated the association between victimization and depressive symptoms. Moreover, direct association and the mediating effect of the sense of security were moderated by psychological capital. The moderating effect occurred in the second half of the mediating effect. LIMITATIONS: Causal conclusions cannot be drawn based on cross-sectional research design. All measures were based on participant self-report. CONCLUSIONS: The mediating model constructed in this study emphasized the important influence of stress, emotion, and psychological diathesis on adolescent depressive symptoms.

Bacillus aquiflavi sp. nov., isolated from yellow water of strongly flavored Chinese baijiu.

A Gram-stain-positive, strictly aerobic and rod-shaped bacterium, designated as 3 H-10T, was isolated from a yellow water sample collected from the manufacturing process of strong flavor Chinese baijiu in Yibin region of Sichuan province (PR China). Oval endospores were formed at the subtermini of cells with swollen sporangia. The isolate was able to grow at temperatures of 20-45 °C (optimum growth at 37 °C), at pH 6.0-10.0 (optimum growth at pH 8.0) and in the presence of 0-2 % (w/v) NaCl (optimum growth with 0 % NaCl). Ribose was the major cell-wall sugar, and meso-diaminopimelic acid (meso-DAP) was the diagnostic amino acid. The main polar lipids of 3 H-10T included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). MK-7 was predominant menaquinone and iso-C15 : 0 (60.7 %) was the major fatty acid. Comparisons of 16S rRNA gene sequence indicated that 3 H-10T was most closely related to Bacillus mesophilus SA4T (96.30 %), Bacillus ginsengihumi Gsoil 114T (96.27 %) and Bacillus shackletonii LMG 18435T (96.27 %). The average nucleotide identity (ANI) values between strain 3 H-10T and the three type strains mentioned above were 69.56, 70.19 and 70.67 %, respectively. The genomic DNA G+C content was 35.4 mol%. On the basis of its phenotypic, chemotaxonomic and phylogenetic properties, strain 3 H-10T represents a novel species of the genus Bacillus, for which the name Bacillus aquiflavi sp. nov. is proposed. The type strain is Bacillus aquiflavi 3 H-10T (=CICC 24755T=JCM 33703T).

Sonochemistry-enabled uniform coupling of SnO2 nanocrystals with graphene sheets as anode materials for lithium-ion batteries.

SnO2/graphene nanocomposite was successfully synthesized by a facile sonochemical method from SnCl2 and graphene oxide (GO) precursors. In the sonochemical process, the Sn2+ is firstly dispersed homogeneously on the GO surface, then in situ oxidized to SnO2 nanoparticles on both sides of the graphene nanosheets (RGO) obtained by the reduction of GO under continuous ultrasonication. Graphene not only provides a mechanical support to alleviate the volume changes of the SnO2 anode and prevent nanoparticle agglomeration, but also serves as a conductive network to facilitate charge transfer and Li+ diffusion. When used as a lithium ion battery (LIB) anode, the SnO2/graphene nanocomposite exhibits significantly improved specific capacity (1610 mA h g-1 at 100 mA g-1), good cycling stability (retaining 87% after 100 cycles), and competitive rate performance (273 mA h g-1 at 500 mA g-1) compared to those of bare SnO2. This sonochemical method can be also applied to the synthesis of other metal-oxide/graphene composites and this work provides a large-scale preparation route for the practical application of SnO2 in lithium ion batteries.

Rational Design of Cathode Structure for High Rate Performance Lithium-Sulfur Batteries.

Practical applications of Li-S batteries require not only high specific capacities and long cycle lifetimes but also high rate performance. We report a rationally designed Li-S cathode, which consists of a freestanding composite thin film assembled from S nanoparticles, reduced graphene oxide (rGO), and a multifunctional additive poly(anthraquinonyl sulfide) (PAQS). The S nanoparticles provide a high initial specific capacity, and the layered and porous rGO structure provides electron and ion transport paths and restricts polysulfide shuttling. PAQS is not only a highly efficient sulfide trapping agent but also an excellent Li(+) conductor, which benefits the battery reaction kinetics at a high rate. The resulting cathode exhibits an initial specific capacity of 1255 mAh g(-1) with a decay rate as low as 0.046% per cycles over 1200 cycles. Importantly, it displays a reversible capacity of 615 mAh g(-1) when discharged at a high rate of 8 C (13.744 A g(-1)).

Powder, paper and foam of few-layer graphene prepared in high yield by electrochemical intercalation exfoliation of expanded graphite.

A facile and high-yield approach to the preparation of few-layer graphene (FLG) by electrochemical intercalation exfoliation (EIE) of expanded graphite in sulfuric acid electrolyte is reported. Stage-1 H2SO4-graphite intercalation compound is used as a key intermediate in EIE to realize the efficient exfoliation. The yield of the FLG sheets (<7 layers) with large lateral sizes (tens of microns) is more than 75% relative to the total amount of starting expanded graphite. A low degree of oxygen functionalization existing in the prepared FLG flakes enables them to disperse effectively, which contributes to the film-forming characteristics of the FLG flakes. These electrochemically exfoliated FLG flakes are integrated into several kinds of macroscopic graphene structures. Flexible and freestanding graphene papers made of the FLG flakes retain excellent conductivity (≈24,500 S m(-1)). Three-dimensional (3D) graphene foams with light weight are fabricated from the FLG flakes by the use of Ni foams as self-sacrifice templates. Furthermore, 3D graphene/Ni foams without any binders, which are used as supercapacitor electrodes in aqueous electrolyte, provide the specific capacitance of 113.2 F g(-1) at a current density of 0.5 A g(-1), retaining 90% capacitance after 1000 cycles.

High-density three-dimension graphene macroscopic objects for high-capacity removal of heavy metal ions.

The chemical vapor deposition (CVD) fabrication of high-density three-dimension graphene macroscopic objects (3D-GMOs) with a relatively low porosity has not yet been realized, although they are desirable for applications in which high mechanical and electrical properties are required. Here, we explore a method to rapidly prepare the high-density 3D-GMOs using nickel chloride hexahydrate (NiCl2·6H2O) as a catalyst precursor by CVD process at atmospheric pressure. Further, the free-standing 3D-GMOs are employed as electrolytic electrodes to remove various heavy metal ions. The robust 3D structure, high conductivity (~12 S/cm) and large specific surface area (~560 m²/g) enable ultra-high electrical adsorption capacities (Cd²âº ~ 434 mg/g, Pb²âº~ 882 mg/g, Ni²âº ~ 1,683 mg/g, Cu²âº ~ 3,820 mg/g) from aqueous solutions and fast desorption. The current work has significance in the studies of both the fabrication of high-density 3D-GMOs and the removal of heavy metal ions.

[Serum myeloperoxidase activity and serum paraoxonase-1 activity in patients with silicosis and observation subjects and their clinical significance].

OBJECTIVE: To investigate the serum myeloperoxidase (MPO) activity and serum paraoxonase-1 (PON-1) activity in patients with silicosis and observation subjects and their clinical significance. METHODS: Seventy-two patients with silicosis (stage I: 30 cases, stage II: 22 cases, stage III: 20 cases) and 37 observation subjects were selected as a case group, and 110 healthy men were selected as a control group. Serum MPO activity was measured by double-antibody sandwich enzyme-linked immunosorbent assay, and serum PON-1 activity was measured by chemical spectrophotometry. RESULTS: Serum MPO activity was significantly higher in the case group than in the control group [(102.1 ± 15.7) U/L vs. (62.4 ± 11.4) U/L, P < 0.01], but serum PON-1 activity was significantly lower in the case group than in the control group [(85.4 ± 15.7) U/ml vs. (125.4 ± 13.7) U/ml, P < 0.01]. Serum MPO activity was significantly lower in patients with stages I, II, and III silicosis than in the observation subjects [(91.3 ± 13.5) U/L, (85.7 ± 14.4) U/L, and (88.6 ± 14.5) U/L vs. (128.4 ± 16.4) U/L, P < 0.01]. Serum PON-1 activity declined as the stage of silicosis increased; serum PON-1 activity was significantly lower in the patients with stages II and III silicosis than in the observation subjects and the patients with stage I silicosis [(70.4 ± 11.4) U/ml and (67.6 ± 13.7) U/ml vs. (101.5 ± 14.0) U/ml and (89.1 ± 10.1) U/ml, P < 0.01]. CONCLUSION: Serum MPO activity and serum PON-1 activity are valuable for early diagnosis of silicosis and evaluation of patient's condition.

Interlayer catalytic exfoliation realizing scalable production of large-size pristine few-layer graphene.

Mass production of reduced graphene oxide and graphene nanoplatelets has recently been achieved. However, a great challenge still remains in realizing large-quantity and high-quality production of large-size thin few-layer graphene (FLG). Here, we create a novel route to solve the issue by employing one-time-only interlayer catalytic exfoliation (ICE) of salt-intercalated graphite. The typical FLG with a large lateral size of tens of microns and a thickness less than 2 nm have been obtained by a mild and durative ICE. The high-quality graphene layers preserve intact basal crystal planes owing to avoidance of the degradation reaction during both intercalation and ICE. Furthermore, we reveal that the high-quality FLG ensures a remarkable lithium-storage stability (>1,000 cycles) and a large reversible specific capacity (>600 mAh g(-1)). This simple and scalable technique acquiring high-quality FLG offers considerable potential for future realistic applications.