Synthesis and evaluation of the SERS effect of Fe3O4–Ag Janus composite materials for separable, highly sensitive substrates

Fe3O4–Ag Janus composites were synthesized using a two-step solvothermal method. The optimal growth process was determined by investigating the relationship between the particle morphologies and reaction time. Magnetic and Raman spectroscopic measurements showed that the as-synthesized Janus composites have both good magnetic response and significant surface-enhanced Raman scattering (SERS) effects, as well as reproducibility. The calculated Raman enhancement factor reached an unprecedented magnitude of 109 compared with the values of other Fe3O4–Ag compounds. Furthermore, the SERS effect was exhibited even at a concentration of probe molecules as low as 10−13 M. This demonstrates that the as-synthesized Fe3O4–Ag Janus composite particles have promise for application as separable, highly sensitive SERS substrates

Residue Behavior and Dietary Exposure Risk Assessment of Acetamiprid and Pyriproxyfen in Citrus Fruit

Objective: Field trials were conducted in 13 citrus production regions including Hunan and Hubei provinces to evaluate the safety of the application of acetamiprid and pyriproxyfen on citrus. The residue, dissipation dynamics and dietary risk assessment of acetamiprid and pyriproxyfen in citrus fruit were investigated. Methods: The samples were extracted with 1% acetic acid in acetonitrile, purified using a mixture of primary secondary amine and graphitized carbon black, and detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Results: Excellent linearity (R2 > 0.99) was observed between the response peak area and the concentration of acetamiprid and pyriproxyfen in the range of 0.001–0.5 mg/L. In whole citrus fruit and flesh spiked at 0.01, 0.5 and 2.5 mg/kg, the recoveries of acetamiprid and pyriproxyfen ranged from 83.0% to 104.3% and from 74.8% to 98.7% with relative standard deviation (RSDs) of 3.8% to 10.0% and 2.0 to 6.0%, respectively. The limits of quantification (LOQs) for the analytes were both 0.01 mg/kg. The dissipation dynamics of acetamiprid and pyriproxyfen in whole citrus fruit was fitted to a first-order kinetics model. The degradation half-lives of acetamiprid and pyriproxyfen in whole citrus fruit were 5.1–15.8 days and 4.5–21.2 days, respectively. Twenty-seven percent acetamiprid-pyriproxyfen dispersible concentrate was sprayed twice on citrus at the recommended dosage of 500 g/hm2 (2 000 × dilution). At a 7-day safety interval, the residues of acetamiprid and pyriproxyfen in citrus fruit ranged from less than 0.01 mg/kg to 0.45 mg/kg and to 0.68 mg/kg, respectively. At a 10-day safety interval, the residues of acetamiprid and pyriproxyfen in citrus fruit ranged from less than 0.01 mg/kg to 0.40 mg/kg and to 0.56 mg/kg, respectively and were both lower than the maximum residue limits (MRLs) for acetamiprid (0.5 mg/kg) and pyriproxyfen (2.0 mg/kg) according to the Chinese national standard. The risk assessment results showed that the acute and chronic dietary exposure risk of acetamiprid and pyriproxyfen ranged from 0.0% to 53.0% (much lower than 100%) for people in different age groups, which was at an acceptable level. Conclusion: This study can provide guidance for the safety evaluation and rational application of acetamiprid and pyriproxyfen in citrus

Research Progress on Diapause in Flies (Diptera)

Diapause is a physiological process in which insects can survive in a natural environment that is not conducive to their survival, which is the result of long-term adaptation to environmental conditions. It provides a great adaptive advantage for insects, allowing insects to survive in unsuitable seasonal environments to synchronize their life cycles with those suitable for growth, development, and reproduction. The process of regulating insect diapause is a complex process interacting with multiple mechanisms. In this chapter, a review is given of the current knowledge of diapause types, environmental inducing factors, sensitive states, and the endogenous molecular mechanism associated with diapause in flies (Diptera). Research regarding both the diapause process and intrinsic mechanism is reviewed

Revision of the Subgenus Burlinius Lopatin (Coleoptera, Chrysomelidae, Cryptocephalinae) from China and Description of Four New Species

This study revised the subgenus Burlinius Lopatin, 1965, of the genus Cryptocephalus Geoffroy, 1762 (Coleoptera, Chrysomelidae, Cryptocephalinae, Cryptocephalini), and describes four new species, namely, Cryptocephalus (Burlinius) longchiensis sp. nov., C. (Burlinius) baowenzhengi sp. nov., C. (Burlinius) tomurensis sp. nov., and C. (Burlinius) glabrelegantulus sp. nov. The species C. (Burlinius) turpis Chen, 1942, and C. (Burlinius) yangweii Chen, 1942, were revalidated and treated as distinct species. Another four species were transferred into this subgenus from the subgenus Cryptocephalus, namely, C. (Burlinius) flavolimbatus Pic, 1920 (stat. nov.), C. (Burlinius) pusus Schöller, 2009 (stat. nov.), C. (Burlinius) scutemaculatus Tan, 1992 (stat. nov.), and C. (Burlinius) shaowuanus Gressitt & Kimoto, 1961 (stat. nov.). Two species (including one more subspecies) were removed out of this subgenus, namely, C. (Burlinius) nigrolimbatus Jacoby, 1890, C. (Burlinius) pallidipes Pic, 1927, and C. (Burlinius) pallidipes nakatae Gressitt & Kimoto, 1961; they were transferred into the subgenus Cryptocephalus. Thus, the subgenus Burlinius Lopatin includes now a total of 26 species in China according to our revision. A key to all the Chinese species of this subgenus is provided as well as color illustrations and line drawings for the general habitus and genital structures

Taxonomy of the Cryptocephalus heraldicus Group (Coleoptera: Chrysomelidae, Cryptocephalinae) from China

This is a study on the leaf beetle subgenus Cryptocephalus Geoffroy, 1762 from China, with the particular emphasis upon the species-group classification of the subgenus and the taxonomy of the Cryptocephalus heraldicus species group. A new key is compiled to all the species groups found in China. Four new species are described from China: Cryptocephalus (Cryptocephalus) biordopunctatus sp. nov. from Yunnan, C. hani sp. nov. from Shanxi, Hubei, Shaanxi and Gansu, C. incisodentatus sp. nov. from Sichuan and Yunnan, and C. nigroflavusiventerus sp. nov. from Yunnan. Three species are found for the first time in China: C. lacosus Pic, 1922, C. nigriceps Allard, 1891 and C. rajah Jacoby, 1908. The species C. nigrolimbatus Jacoby, 1890 is transferred from the subgenus Burlinius Lopatin to this subgenus and assigned to the Cryptocephalus heraldicus group. The species number of this group is now 30 in total according to our result of taxonomic review. A key to all the mainland China species of this species group is provided as well as high quality color images and line drawings of adult habitus, aedeagus, and other important structures. All the types of the new species are deposited in the collection of Institute of Zoology, Chinese Academy of Sciences (IZ-CAS)

Low Model Analysis and Synchronous Simulation of the Wave Mechanics

The dynamic behavior of a chaotic system in the internal wave dynamics and the problem of the tracing and synchronization are investigated, and the numerical simulation is carried out in this paper. The globally exponentially attractive set and positive invariant set of the chaotic system are studied via constructing the positive definite and radial unbounded Lyapunov function. There are no equilibrium positions, periodic solutions, quasi-period motions, wandering recovering motions, and other chaotic attractors of the system out of the globally exponentially attractive set. Strange attractors can only locate in the globally exponentially attractive set. A feedback controller is designed for the chaotic system to realize the control of the unstable point. The second method of Lyapunov is used to discuss theoretically the rationality of the design of the controller. The driving-response synchronization method is used to realize the globally exponential synchronization. The numerical simulation is carried out by MATLAB software, and the simulation results show that the method is effective

LiF-MO (M=Co, Fe, Ni) Nanocomposite Thin Film as Anode Materials for Lithium-ion Battery

To investigate the electrochemical performance of MO (M=Co, Fe, Ni) nanostructures on lithium insertion and extraction, size-controlled LiF-MO nanocomposite thin-film electrodes, consisting of metallic M and M oxide (MO) nanoparticles in an amorphous, inert LiF matrix, were designed and fabricated using a RF sputtering system with metallic M and LiF mixture targets. The structural and electrochemical properties of nanocomposite thin-film electrodes were characterized using TEM, SAED, XRD, XPS, and electrochemical measurements. The results showed that MO particles with average particle sizes of ca.10nm were well-dispersed in LiF matrix to form a kind of homogeneous LiF-MO nanocomposite by the sputtering method. The inert medium of LiF provides an effective matrix to prevent the crystallization and agglomeration of MO during the deposition and electrochemical cycling of the thin film electrode, and then the well-formed nanophase structure in the nanocomposite thin-film electrodes leads to an excellent electrochemical cycling performance with the stable discharge specific capacity above 300mAh/g.</p

Molecular Docking Characterization of a Four-Domain Segment of Human Fibronectin Encompassing the RGD Loop with Hydroxyapatite

Fibronectin adsorption on biomaterial surfaces plays a key role in the biocompatibility of biomedical implants. In the current study, the adsorption behavior of the 7–10th type III modules of fibronectin (FN-III7–10) in the presence of hydroxyapatite (HAP) was systematically investigated by using molecular docking approach. It was revealed that the FN-III10 is the most important module among FN-III7–10 in promoting fibronectin binding to HAP by optimizing the interaction energy; the arginine residues were observed to directly interact with the hydroxyl group of HAP through electrostatic forces and hydrogen bonding. Moreover, it was found that the HAP-binding sites on FN-III10 are mainly located at the RGD loop region, which does not affect the interaction between the fibronectin protein and its cognate receptors on the cell surface