Multifunctional metamaterial device based on VO2 and the equivalent diode.

This paper proposes a switchable multifunctional metamaterial device operating in the terahertz (THz) band. The device is loaded with an equivalent diode and utilizes vanadium dioxide (V O 2). The middle layer of the whole device, a metal layer, divides the device into the I side and the II side. When the diode is ON, the I side can achieve dual-band absorption at 1.975 and 4.345 THz. When the diode is OFF, the I side can achieve single-band absorption at 4.28 THz. In the case of V O 2 being insulating, the II side can achieve linear-to-linear (LTL) polarization conversion at 2.342-4.18 THz. In the case of V O 2 being conductive, the II side can realize linear-to-circular (LTC) polarization conversion at 2.105-3.283 THz. The device provides a new strategy for the subsequent combination of multiple functions. The device can be used in electromagnetic stealth, intelligent applications, radiometers, and sensors and has relatively large application potential in miniaturized multifunctional metamaterials and THz band research.

Cefotaxime Exposure-Caused Oxidative Stress, Intestinal Damage and Gut Microbial Disruption in Artemia sinica.

Cefotaxime (CTX) is an easily detectable antibiotic pollutant in the water environment, but little is known about its toxic effects on aquatic invertebrates, especially on the intestine. Here, we determined the oxidative stress conditions of A. sinica under CTX exposure with five concentrations (0, 0.001, 0.01, 0.1 and 1 mg/L) for 14 days. After that, we focused on changes in intestinal tissue morphology and gut microbiota in A. sinica caused by CTX exposure at 0.01 mg/L. We found malondialdehyde (MDA) was elevated in CTX treatment groups, suggesting the obvious antibiotic-induced oxidative stress. We also found CTX exposure at 0.01 mg/L decreased the villus height and muscularis thickness in gut tissue. The 16S rRNA gene analysis indicated that CTX exposure reshaped the gut microbiota diversity and community composition. Proteobacteria, Actinobacteriota and Bacteroidota were the most widely represented phyla in A. sinica gut. The exposure to CTX led to the absence of Verrucomicrobia in dominant phyla and an increase in Bacteroidota abundance. At the genus level, eleven genera with an abundance greater than 0.1% exhibited statistically significant differences among groups. Furthermore, changes in gut microbiota composition were accompanied by modifications in gut microbiota functions, with an up-regulation in amino acid and drug metabolism functions and a down-regulation in xenobiotic biodegradation and lipid metabolism-related functions under CTX exposure. Overall, our study enhances our understanding of the intestinal damage and microbiota disorder caused by the cefotaxime pollutant in aquatic invertebrates, which would provide guidance for healthy aquaculture.

Sequence analysis of the ATP synthase of subunits (ATP8 and ATP6) genes of mitochondrial DNA genome from Ailuropoda melanoleuca.

To explore the effects of the mutations of ATP6 and ATP8 genes on energy metabolism and genetic structure, we sequenced the ATP6 and ATP8 genes of Ailuropoda melanoleuca. Our results showed that ATP8 is a conserved gene and ATP6 gene is positively selected during the evolution of the giant panda population with a low genetic diversity. Population expansion was observed in the giant panda group. The T179C mutation on Haplotype7 made the production of a potential phosphorylation site. This non-synonymous mutation may occur at the post-translational modification site that have a potential effect on the function of ATP synthase, related to the maintenance of body temperature of pandas at low metabolic rates.

Complete mitochondrial genome sequence of Jianmen-guan phasianus colchicus (Aves, Gallifoemes, phasianidae) and its phylogenetic analysis.

Jianmen-guan phasianus colchicusare one of the most important and be cherished uncultivated animals, although, origins of the most J. phasianus colchicus remain unknown. Therefore, the complete mitochondrial genome of the J. phasianus colchicus (also named seven-colours J. phasianus colchicus, one of the oldest wild birds in China known for their preciousness) was obtained for the first time, the mitogenome is 166,786 bp in length, and it harbours 2rRNA genes, 13 protein-coding genes, 22tRNA genes, and a D-loop region. According to the phylogenetic tree, we can assume that Jianmen-guan and Xianju are within the same lineage, and J. phasianus colchicus is a different group with Red Jungle.

Analysis of the cytochrome c oxidase subunit 1 (COX1) gene reveals the unique evolution of the giant panda.

As the rate-limiting enzyme of the mitochondrial respiratory chain, cytochrome c oxidase (COX) plays a crucial role in biological metabolism. "Living fossil" giant panda (Ailuropoda melanoleuca) is well-known for its special bamboo diet. In an effort to explore functional variation of COX1 in the energy metabolism behind giant panda's low-energy bamboo diet, we looked at genetic variation of COX1 gene in giant panda, and tested for its selection effect. In 1545 base pairs of the gene from 15 samples, 9 positions were variable and 1 mutation leaded to an amino acid sequence change. COX1 gene produces six haplotypes, nucleotide (pi), haplotype diversity (Hd). In addition, the average number of nucleotide differences (k) is 0.001629±0.001036, 0.8083±0.0694 and 2.517, respectively. Also, dN/dS ratio is significantly below 1. These results indicated that giant panda had a low population genetic diversity, and an obvious purifying selection of the COX1 gene which reduces synthesis of ATP determines giant panda's low-energy bamboo diet. Phylogenetic trees based on the COX1 gene were constructed to demonstrate that giant panda is the sister group of other Ursidae.

Anti-methicillin-resistant Staphylococcus aureus assay of azalomycin F5a and its derivatives.

AIM: To discover anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) microbial natural products or their derivatives. METHOD: Azalomycin F5a (1) was prepared through fermentation of Streptomyces hygroscopicus var. azalomyceticus, and its derivatives were synthesized through hydrocarbylation in hydrocarbyl alcoholic-AcOH (4 : 1) and subsequent demalonylation with 2 mol·L(-1) KOH in MeOH-H2O (7 : 3). Their activities against MRSA ATCC 33592 and three clinical MRSA isolates were evaluated by the agar diffusion and broth microdilution methods. RESULTS: Four demalonylazalomycin F5a derivatives 2 to 5 were synthesized. The anti-MRSA activity assay indicated that compounds 1 to 5 showed remarkable activity against MRSA, and their minimum inhibitory concentrations (MICs) were respectively 3.0-4.0, 0.5-1.0, 0.67-1.0, 0.67-0.83, and 0.5-0.83 µg·mL(-1). CONCLUSION: Azalomycin F5a and the demalonylazalomycin F5a derivatives 2-5 showed remarkable anti-MRSA activity, and the anti-MRSA activities of 2 to 5 were higher than that of 1, while the anti-MRSA activities of 2 to 5 showed no obvious differences. It was also shown that the malonyl monoester group of azalomycin F5a was less important for its anti-MRSA activity.

Hemolymph juvenile hormone titers in worker honey bees under normal and preswarming conditions.

Swarming is an important mechanism by which honey bee, Apis mellifera L., colonies reproduce, yet very little is known about the physiological changes in workers that are preparing to swarm. In this study, we determined the endocrine status of worker honey bees in preswarming colonies and in normal (nonswarming) colonies. Juvenile hormone (JH) titers in worker bees were similar in both groups before queen cells were present, but they became significantly lower in preswarming colonies compared with normal colonies when queen cells occurred in preswarming colonies. The lower JH titers in the preswarming colonies suggest that behavioral development is delayed in these colonies, consistent with previous reports that preswarming colonies have reduced foraging activities. Understanding the endocrine status of bees preparing for swarming will help us to better understand the biology of swarming.