Laboratory pull-out tests were conducted on the following rock bolts and cable bolts:steel rebars,smooth steel bars,fiberglass reinforced polymer threaded bolts,flexible cable bolts,IR5/IN special cable bolts and Mini...Laboratory pull-out tests were conducted on the following rock bolts and cable bolts:steel rebars,smooth steel bars,fiberglass reinforced polymer threaded bolts,flexible cable bolts,IR5/IN special cable bolts and Mini-cage cable bolts.The diameter of the tested bolts was between 16 mm and 26 mm.The bolts were grouted in a sandstone sample using resin or cement grouts.The tests were conducted under either constant radial stiffness or constant confining pressure boundary conditions applied on the outer surface of the rock sample.In most tests,the rate of displacement was about 0.02 mm/s.The tests were performed using a pull-out bench that allows testing a wide range of parameters.This paper provides an extensive database of laboratory pull-out test results and confirms the influence of the confining pressure and the embedment length on the pull-out response(rock bolts and cable bolts).It also highlights the sensitivity of the results to the operating conditions and to the behavior of the sample as a whole,which cannot be neglected when the test results are used to assess the bolt-grout or the grouterock interface.展开更多
The haloarchaea Haloferax mediterranei and Haloarcula hispanica are both polyhydroxyalkanoate producers in the domain Archaea, and they are becoming increasingly attractive for research and biotechnology due to their ...The haloarchaea Haloferax mediterranei and Haloarcula hispanica are both polyhydroxyalkanoate producers in the domain Archaea, and they are becoming increasingly attractive for research and biotechnology due to their unique genetic and metabolic features. To accelerate their genome-level genetic and metabolic analyses, we have developed specific and highly efficient gene knockout systems for these two haloarchaea. These gene knockout systems consist of a suicide plasmid vector with the pyrF gene as the selection marker and a uracil auxotrophic haloarchaeon （apyrF） as the host. For in-frame deletion of a target gene, the suicide plasmid carrying the flanking region of the target gene was transferred into the corresponding apyrF host. After positive selection of the single-crossover integration recombinants （pop-in） on AS-168SY medium without uracil and counterselection of the double-crossover pyrF-excised recombinants （pop-out） with 5-fluoroorotic acid （5-FOA）, the target gene knockout mutants were confirmed by PCR and Southern blot analysis. We have demonstrated the effectiveness of these systems by knocking out the crtB gene which encodes a phytoene synthase in these haloarchaea. In conclusion, these well-developed knockout systems would greatly accelerate the functional genomic research of these halophilic archaea.展开更多
基金supported by the European Research Fund for Coal and Steel in the AMSSTED Programme RFCR-CT-2013-00001
文摘Laboratory pull-out tests were conducted on the following rock bolts and cable bolts:steel rebars,smooth steel bars,fiberglass reinforced polymer threaded bolts,flexible cable bolts,IR5/IN special cable bolts and Mini-cage cable bolts.The diameter of the tested bolts was between 16 mm and 26 mm.The bolts were grouted in a sandstone sample using resin or cement grouts.The tests were conducted under either constant radial stiffness or constant confining pressure boundary conditions applied on the outer surface of the rock sample.In most tests,the rate of displacement was about 0.02 mm/s.The tests were performed using a pull-out bench that allows testing a wide range of parameters.This paper provides an extensive database of laboratory pull-out test results and confirms the influence of the confining pressure and the embedment length on the pull-out response(rock bolts and cable bolts).It also highlights the sensitivity of the results to the operating conditions and to the behavior of the sample as a whole,which cannot be neglected when the test results are used to assess the bolt-grout or the grouterock interface.
基金supported by the National Natural Science Foundation of China(Nos.30830004,30925001)the National 863 Program of China(No.2009AA09Z401)the Chinese Academy of Sciences(No.KSCX2-EW-G-2)
文摘The haloarchaea Haloferax mediterranei and Haloarcula hispanica are both polyhydroxyalkanoate producers in the domain Archaea, and they are becoming increasingly attractive for research and biotechnology due to their unique genetic and metabolic features. To accelerate their genome-level genetic and metabolic analyses, we have developed specific and highly efficient gene knockout systems for these two haloarchaea. These gene knockout systems consist of a suicide plasmid vector with the pyrF gene as the selection marker and a uracil auxotrophic haloarchaeon （apyrF） as the host. For in-frame deletion of a target gene, the suicide plasmid carrying the flanking region of the target gene was transferred into the corresponding apyrF host. After positive selection of the single-crossover integration recombinants （pop-in） on AS-168SY medium without uracil and counterselection of the double-crossover pyrF-excised recombinants （pop-out） with 5-fluoroorotic acid （5-FOA）, the target gene knockout mutants were confirmed by PCR and Southern blot analysis. We have demonstrated the effectiveness of these systems by knocking out the crtB gene which encodes a phytoene synthase in these haloarchaea. In conclusion, these well-developed knockout systems would greatly accelerate the functional genomic research of these halophilic archaea.
