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This paper investigates the long-term influence of aged asphalt in reclaimed asphalt pavement (RAP) on the mechanical properties of the cold recycled mixture (CRM) with emulsified asphalt. Firstly, RAP was simulated by the long-term aging method. On this basis, indirect tensile strength tests were conducted to discern the long-term strength with different aged asphalt dosages (0%, 2%, and 4%) and aging degrees (0, 4, 8, and 15 h) of RAP. After accelerated curing, the indirect tensile strength (ITS) and fracture energy ( E f ) were measured and the area ratio of uncoated aggregates of the fractured surface (Ra) was established by image processing to reflect the long-term growth mechanism of strength. Considering the unfavourable states, interfacial drawing and shear tests were executed with different aging degree, load, interfacial contact and thickness of aged asphalt films. Results indicated that the strength increased with aged asphalt dosages of RAP, whereas aging degree had the opposite effect. Moreover, aging degrees, clean surface and external load are all salutary to the long-term adhesion of CRM, obviously. Therefore, it is proved that RAP makes contributions to the long-term growth in mechanical properties of CRM, which is also significant to sustainable asphalt pavement maintenance. [ABSTRACT FROM AUTHOR]

In the present study, chitosan-coated octadecyl-functionalized magnetite nanoparticles ([Fe.sub.3][O.sub.4]-[C.sub.18]-chitosan MNPs) are synthesized and used as an adsorbent to extract trace analytes from environmental water samples. The magnetic nanoparticles, 20 nm in diameter, are of uniform size and have a high magnetic saturation value of 52 emu [g.sup.1], which endue the adsorbent with a large surface area and convenience of isolation. The anionic pollutants, perfluorinated compounds (PFCs), are trapped by the octadecyl group of the interior hydrophobic layer. The positively charged chitosan polymer coating also contributes to PFC enrichment. At the same time, the coating improves the dispersibility of MNPs in aqueous solution and enhances the anti-interference ability of the adsorbent to natural organic macromolecules in complex samples by size exclusion or electrostatic repulsion. A liquid chromatography tandem mass spectrometry system is employed in the determination of PFCs after preconcentration with the MNP adsorbent. The predominant factors affecting preconcentration are investigated and optimized. Under the selected conditions, concentration factors of 1000 are achieved by extracting the analytes from 500 mL of several environmental water samples and concentrating the eluants to 0.5 mL with a nitrogen flow. The method detection limits obtained for perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), and perfluorotetradecanoic acid (PFTA) in Gaobeidian wastewater are 0.24, 0.093, 0.24, 0.14, 0.075, 0.24, and 0.17 ng [L.sup.1], respectively. Recoveries of PFOA, PFOS, PFNA, PFDA, PFUnDA, PFDoDA, and PFTA are in the ranges of 88-108%, 63-112%, 79-109%, 56-107%, 66-106%, 56-106%, and 66-103% for four spiked water samples with low relative standard deviation (2-8%), which indicates good method precision. The advantages of this novel adsorbent are high extraction efficiency, anti-interference, and convenient operation. 10.1021/ac902589t

Streptomyces ansochromogenes SanG is a pathway-specific regulator that mainly controls the transcription of two transcriptional units involved in nikkomycin biosynthesis. SanG consists of three major functional domains: an N-terminal Streptomyces antibiotic regulatory protein (SARP) domain, a central ATPase domain, and a C-terminal half homologous to guanylate cyclases belonging to the LuxR family. SanG was expressed in Escherichia coil as a C-terminally [His.sub.6]tagged protein. The purified SanG-[His.sub.6] was shown to be a dimer in solution by dynamic light scattering. An electrophoretic mobility-shift assay showed that the purified SanG protein could bind to the DNA fragment containing the bidirectional sanN--sanQ promoter region. The SanG-binding sites within the bidirectional sanN--sanQ promoter region were determined by footprinting analysis and identified a consensus-directed repeat sequence 5'-CGGCAAG-3'. SanG showed significant ATPase/GTPase activity in vitro, and addition of ATP/GTP enhanced the affinity of SanG for target DNA, but ATP/GTP hydrolysis was not essential for SanG binding to the target DNA. However, real-time reverse transcription PCR showed that mutation of the ATPase/GTPase domain of Sang significantly decreased the transcriptional level of sanN--I and sanO--V. These results indicated that the ATPase/GTPase activity of SanG modulated the transcriptional activation of SanG target genes during nikkomycin biosynthesis. DOI 10.1099/mic.0.033605-0

Summary: Heterologous expression of the biosynthetic gene cluster (BGC) is important for studying the microbial natural products (NPs), especially for those kept in silent or poorly expressed in their original strains. Here, we cloned the spinosad BGC through the Cas9‐Assisted Targeting of Chromosome segments and amplified it to five copies through a ZouA‐dependent DNA amplification system in Streptomyces coelicolor M1146. The resulting strain produced 1253.9 ± 78.2 μg l−1 of spinosad, which was about 224‐fold compared with that of the parent strain carrying only one copy of the spinosad BGC. Moreover, we further increased spinosad to 1958.9 ± 73.5 μg l−1 by the dynamic regulation of intracellular triacylglycerol degradation. Our study indicates that tandem amplification of the targeted gene cluster is particularly suitable to enhance the heterologous production of valuable NPs with efficiency and simplicity. [ABSTRACT FROM AUTHOR]

Forests play an important role in sequestrating carbon from the atmosphere. Since the 1980s, reforestation activities have been implemented in the area surrounding the Qianyanzhou Forest Experimental Station in Jiangxi Province, China. Farmland and heavily eroded waste land were replanted with fruit, orchards and forest plantations. The area surrounding the Qianyanzhou Forest Experimental Station was selected as research site to analyze the potential of reforestation in carbon sequestration. This study evaluates the variation of soil organic carbon storage under the different land use types. Soil organic carbon storage varied greatly with land use types. From 1984 to 2002, soil organic carbon storage increased 2.45 x [10.sup.6] kg across eight land use types. This study demonstrates the potential for carbon sequestration in soils from reforestation. However, a complete understanding of soil carbon fluxes at the landscape scale will depend on the potential and retention period of soil organic carbon.