Decoding the mechanical conductance switching behaviors of dipyridyl molecular junctions.

Dipyridyl molecular junctions often show intriguing conductance switching behaviors with mechanical modulations, but the mechanisms are still not completely revealed. By applying the ab initio-based adiabatic simulation method, the configuration evolution and electron transport properties of dipyridyl molecular junctions in stretching and compressing processes are systematically investigated. The numerical results reveal that the dipyridyl molecular junctions tend to form specific contact configurations during formation processes. In small electrode gaps, the pyridyls almost vertically adsorb on the second Au layers of the tip electrodes by pushing the top Au atoms aside. These specific contact configurations result in stronger molecule-electrode couplings and larger electronic incident cross-sectional areas, which consequently lead to large breaking forces and high conductance. On further elongating the molecular junctions, the pyridyls shift to the top Au atoms of the tip electrodes. The additional scattering of the top Au atoms dramatically decreases the conductance and switches the molecular junctions to the lower conductive states. Perfect cyclical conductance switches are obtained as observed in the experiments by repeatedly stretching and compressing the molecular junctions. The O atom in the side-group tends to hinder the pyridyl from adsorbing on the second Au layer and further inhibits the conductance switch of the dipyridyl molecular junction.

Attenuation of veterinary antibiotics in full-scale vermicomposting of swine manure via the housefly larvae (Musca domestica).

Animal waste from concentrated swine farms is widely considered to be a source of environmental pollution, and the introduction of veterinary antibiotics in animal manure to ecosystems is rapidly becoming a major public health concern. A housefly larvae (Musca domestica) vermireactor has been increasingly adopted for swine manure value-added bioconversion and pollution control, but few studies have investigated its efficiency on antibiotic attenuation during manure vermicomposting. In this study we explored the capacity and related attenuation mechanisms of antibiotic degradation and its linkage with waste reduction by field sampling during a typical cycle (6 days) of full-scale larvae manure vermicomposting. Nine antibiotics were dramatically removed during the 6-day vermicomposting process, including tetracyclines, sulfonamides, and fluoroquinolones. Of these, oxytetracycline and ciprofloxacin exhibited the greater reduction rate of 23.8 and 32.9 mg m(-2), respectively. Environmental temperature, pH, and total phosphorus were negatively linked to the level of residual antibiotics, while organic matter, total Kjeldahl nitrogen, microbial respiration intensity, and moisture exhibited a positive effect. Pyrosequencing data revealed that the dominant phyla related to Firmicutes, Bacteroidetes, and Proteobacteria accelerated manure biodegradation likely through enzyme catalytic reactions, which may enhance antibiotic attenuation during vermicomposting.

Insight into the effect of hydrogenation on efficiency of hydrothermal liquefaction and physico-chemical properties of biocrude oil.

Hydrothermal liquefaction of Nannochloropsis salina (N. salina) and larvae-vermicompost were conducted under both non-hydrogenating and hydrogenating subcritical conditions using H2 and Ni-Mo/Al2O3. Hydrogenation raised biocrude yields from 33.2% to 43.5% (vermicompost) and 55.6% to 78.5% (N. salina), whereas high heat values increased from 32.89 to 34.24 MJ/kg (vermicompost) and 36.30 to 37.53 MJ/kg (N. salina). Compared with the non-hydrogenated HTL process, the contents of acids, amides, phenols, and alcohols decreased, whereas hydrocarbons content increased. More branched cyclic nitrogenous compounds were detected in the hydrogenated biocrudes, whereas the aromatic/hetero-aromatic functionality was somewhat decreased. Smaller molecular weights and polydispersity index of the hydrogenated biocrudes were also detected. Results show that hydrogenation enhanced the removal of hydrophilic functional groups and the stabilization of radicals, thereby leading to the inhibition of loss of mass toward liquid and gaseous products and the upgrading of oil quality.

Cloning and characterization of a surface antigen CiSA-32.6 from Cryptocaryon irritans.

Cryptocaryon irritans is a ciliated parasite causing cryptocaryosis in marine fish. To isolate functional genes, a cDNA library of C. irritans trophonts was constructed and a gene designated CiSA-32.6 (GenBank ID: JF812643) was cloned and characterized. The full-length cDNA (1158 bp) encoded a deduced polypeptide of 330 amino-acid (aa) with a signal peptide of 22 aa. To express the ciliate gene, a truncated open reading frame (CiSA-32.6t) was synthesized to remove fragments encoding the signal peptide and hydrophobic C-terminal and to modify non-universal genetic codes. CiSA-32.6t was subcloned into Escherichia coli DH5α strain using the pGEX-4T-1 vector and then expressed as a glutathione S transferase fusion protein (rCiSA-32.6t). Western blotting analysis showed that sera from mice immunized with rCiSA-32.6t reacted specifically with a native protein (32.6 kDa) in parasite lysates. Moreover, rCiSA-32.6t reacted specifically with sera from mice immunized with a C. irritans trophont lysate. Expression of the CiSA-32.6 gene in C. irritans was detected at all developmental stages by reverse transcriptase PCR and Western blotting analysis. This study provides the basis of further investigations into the pathogenic biology of C. irritans and the control of cryptocaryosis.