Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.T...Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.The acoustic local effect in slender columnar structure with two layers of rings in air is investigated.Results prove that when the plane acoustic wave is incident into the model,complex interference and diffraction occur.And at different frequencies,multipolar acoustic local effect existes and cycle distribution phenomenon is observed.It is noteworthy that this phenomenon has very weak relatedness with the materials and acoustic parameters of the model.The research of this metamaterial design in this paper has definite reference significance in the acoustic communication and amplification of the acoustic signal detection.展开更多
The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM)...The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.展开更多
The behavior of slender columns under the effect of eccentric loading has always taken the attention of researchers. When investigating the strengthening of reinforced concrete columns, mainly short and circular colum...The behavior of slender columns under the effect of eccentric loading has always taken the attention of researchers. When investigating the strengthening of reinforced concrete columns, mainly short and circular columns are the targeted elements. This is why the data about slender columns with rectangular sections is limited and infrequent specially when loaded eccentrically. This paper aims to increase the available experimental data in this specific area. The experimental program consisted of twenty seven specimens. The specimens were divided into three groups; one control group and two groups strengthened using two strengthening schemes. Scheme 1 implied the use of near surface mounted (NSM) longitudinal steel bars, while in scheme 2, NSM longitudinal steel bars partially wrapped with one ply of carbon fibers reinforced polymers (CFRP) sheets was used. The test specimen had an overall length of 2000 mm and a 100 x 200 mm rectangular cross section. In addition to the strengthening schemes, the test parameters included three ratios for the internal longitudinal steel bars "μ" 1%, 1.57% and 2.26%. The parameters were extended to cover three stirrups' volumetric ratio "ρv" 0.73%, 0.49% and 0.37%. The specimens were tested under the effect of eccentric loading with eccentricity-to-section height e/h equals 0.25. The research revealed that the strength gain in specimens strengthened with scheme 2 was higher than with scheme 1. Analytical modeling of the stress strain relation of the strengthened RC columns considering the effect of strengthening scheme, internal reinforcement ratio μ, and stirrups' volumetric ratio "ρv" was proposed. Verification was made using available experimental data. The proposed model showed a reasonable agreement with the experimental results.展开更多
This study described a new species of free-living nematode discovered in the intertidal mudflat of Ximen Island,East China Sea.The new species,designated Parodontophora longiamphidata sp.nov.,was characterized by a cy...This study described a new species of free-living nematode discovered in the intertidal mudflat of Ximen Island,East China Sea.The new species,designated Parodontophora longiamphidata sp.nov.,was characterized by a cylindrical body with tapering extremeties;cuticle smooth without somatic setae;four short cephalic setae;cylindrical buccal cavity with six clawlike teeth at the top of stoma;pharynx cylindrical with widened base;amphidial fovea crook-shaped with elongated scalariform branch extending past level of base of pharynx and ventral gland;ventral gland cell long-oval shaped located posterior to pharyngo-intestinal junction;excretory pore at level of middle of buccal cavity;tail conico-cylindrical with enlarged tip;three caudal gland cells,male spicules arched with cephalic proximal end and tapered distal end;gubernaculum with dorso-caudal apophysis;female with two opposed outstretched ovaries;and vulva at slightly post-midpoint of body length.This new species was close to P.wuleidaowanensis Zhang,2005 and P.polita Gerlach,1955 in terms of long amphidial fovea branch.The newly found species was easily distinguishable from the two documented;its amphidial fovea branch(255–290 μm versus 72–106 and 125–150 μm) was obviously longer.Key to the Parodontophora species with a longer amphidial fovea branch was given.展开更多
基金National Natural Science Foundation of China(No.61671414)Natural Science Foundation for Young Scientists of Shanxi Province,China(No.201601D202035)
文摘Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.The acoustic local effect in slender columnar structure with two layers of rings in air is investigated.Results prove that when the plane acoustic wave is incident into the model,complex interference and diffraction occur.And at different frequencies,multipolar acoustic local effect existes and cycle distribution phenomenon is observed.It is noteworthy that this phenomenon has very weak relatedness with the materials and acoustic parameters of the model.The research of this metamaterial design in this paper has definite reference significance in the acoustic communication and amplification of the acoustic signal detection.
基金financial supports from the National Key R&D Program of China(No.2018YFC1801804)the Shandong Provincial Natural Science Foundation,China(Nos.ZR2020QD120 and ZR2018LD001)Project of Introducing and Cultivating Young Talent in the Universities of Shandong Province,China(No.QC2019YY144)。
文摘The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.
文摘The behavior of slender columns under the effect of eccentric loading has always taken the attention of researchers. When investigating the strengthening of reinforced concrete columns, mainly short and circular columns are the targeted elements. This is why the data about slender columns with rectangular sections is limited and infrequent specially when loaded eccentrically. This paper aims to increase the available experimental data in this specific area. The experimental program consisted of twenty seven specimens. The specimens were divided into three groups; one control group and two groups strengthened using two strengthening schemes. Scheme 1 implied the use of near surface mounted (NSM) longitudinal steel bars, while in scheme 2, NSM longitudinal steel bars partially wrapped with one ply of carbon fibers reinforced polymers (CFRP) sheets was used. The test specimen had an overall length of 2000 mm and a 100 x 200 mm rectangular cross section. In addition to the strengthening schemes, the test parameters included three ratios for the internal longitudinal steel bars "μ" 1%, 1.57% and 2.26%. The parameters were extended to cover three stirrups' volumetric ratio "ρv" 0.73%, 0.49% and 0.37%. The specimens were tested under the effect of eccentric loading with eccentricity-to-section height e/h equals 0.25. The research revealed that the strength gain in specimens strengthened with scheme 2 was higher than with scheme 1. Analytical modeling of the stress strain relation of the strengthened RC columns considering the effect of strengthening scheme, internal reinforcement ratio μ, and stirrups' volumetric ratio "ρv" was proposed. Verification was made using available experimental data. The proposed model showed a reasonable agreement with the experimental results.
基金supported by the National Natural Science Foundation of China (No.41176107)
文摘This study described a new species of free-living nematode discovered in the intertidal mudflat of Ximen Island,East China Sea.The new species,designated Parodontophora longiamphidata sp.nov.,was characterized by a cylindrical body with tapering extremeties;cuticle smooth without somatic setae;four short cephalic setae;cylindrical buccal cavity with six clawlike teeth at the top of stoma;pharynx cylindrical with widened base;amphidial fovea crook-shaped with elongated scalariform branch extending past level of base of pharynx and ventral gland;ventral gland cell long-oval shaped located posterior to pharyngo-intestinal junction;excretory pore at level of middle of buccal cavity;tail conico-cylindrical with enlarged tip;three caudal gland cells,male spicules arched with cephalic proximal end and tapered distal end;gubernaculum with dorso-caudal apophysis;female with two opposed outstretched ovaries;and vulva at slightly post-midpoint of body length.This new species was close to P.wuleidaowanensis Zhang,2005 and P.polita Gerlach,1955 in terms of long amphidial fovea branch.The newly found species was easily distinguishable from the two documented;its amphidial fovea branch(255–290 μm versus 72–106 and 125–150 μm) was obviously longer.Key to the Parodontophora species with a longer amphidial fovea branch was given.