Search

In order to investigate the effects of steel fiber, polyvinyl alcohol (PVA) fiber and mineral powder contnet on permeability resistance of steel-PVA hybrid fiber high performance concrete (HFHPC). The orthogonal experiment was designed to conduct the permeability resistance test of steel-PVA HFHPC, and the test results were analyzed through range analysis, variance analysis and regression analysis. The results show that the influence degree on the impermeability of HFHPC is steel fiber, mineral powder and PVA fiber from high to low. In the range of test level, the optimal horizontal combination of impermeability of concrete specimens is as follows: steel fiber volume fraction of 1.0%, PVA fiber volume fraction of 0.7% and slag powder mass replacement rate 20% . When the steel fiber volume fraction exceeds 1.0%, the impermeability of HFHPC decreases slightly, but it is still higher than that of standard plain concrete. Finally, multiple regression analysis is used to establish the prediction model of HFHPC permeability and steel fiber, PVA fiber and mineral powder. [ABSTRACT FROM AUTHOR]

Based on the corridor channel curtain wall reconstruction project at Wuhan Tianhe airport T2-T3 terminal building, the structural system of point supported glass curtain wall with cable structure 18 years ago was analyzed, the technical difficulties of curtain wall glass panel removal and bearing cable removal were studied, and technical measures for the dismantlement and reconstruction of point supported glass curtain wall with cable structure were reasonably proposed. During the construction process of the dismantlement and reconstruction, the curtain wall structure was dynamically monitored, the deformation of the monitoring points were small, and the construction process was in a safe state. Due to the success in the dismantlement and reconstruction control technology of the point supported glass curtain wall with cable structure in this project, it not only ensured the construction safety, but also improved the construction quality, which could provide a reference for other similar projects.

The influence of various seismic parameters on the seismic performance of rectangular reinforced recycled concrete columns was comprehensively revealed through collecting and screening experimental data from 53 rectangular recycled aggregate concrete columns. The research results showed that the bearing capacity of the specimens decreased and the ductility performance increased, which were attributed to the following factors. a. The increase in the replacement ratio and slenderness ratio of recycled coarse aggregate, and b. the reduction in the axial compression ratio and the strength of recycled aggregate concrete. The seismic design limitations and boundary conditions of this study are γ ∈ [0, 100%], n0 ∈ [0, 0.9], λ0 ∈ [5.06, 18.479], λ ∈ [1.09, 3.93], ρsl ∈ [1.01%, 2.45%], ρsv ∈ [1.4%, 5.33%], and f ∈ [C30, C50]. Thus, it is recommended that for the seismic design value of rectangular recycled aggregate concrete columns, the optimal longitudinal reinforcement rate be set at 1.59%. [ABSTRACT FROM AUTHOR]

This paper investigates the seismic behavior of a seismic-damaged double-deck viaduct frame pier (DVFP) strengthened with CFRP and enveloped steel, four strengthened DVFP specimens with different degrees of initial damage were tested under quasi-static cyclic loading. Based on the test results, the hysteretic behavior, the stiffness and strength degradation, crack propagation, and failure mechanism were firstly analyzed. Then, the damage indexes of the tested specimens were calculated with different models to evaluate the seismic strengthening performance. Results of this study show that CFRP and enveloped steel strengthening could effectively improve the strength and ductility of pre-damaged DVFPs. The ultimate load, the failure displacement and the displacement ductility of the moderately damaged specimen after being strengthened were found to increase by 120.74%, 35% and 32.33%, respectively. For the severely damaged specimens with CFRP and enveloped steel strengthening, the figures were 105.36%, 25.98% and 31.41%, respectively. The research results can provide reference for the hybrid strengthening application of seismic-damaged DVFP. [ABSTRACT FROM AUTHOR]

In this paper, an absorber with a resistive film is proposed, which holds stable polarization absorption characteristics at large angles by exploring the principle of absorption structure. The absorber contains three layers: the top layer is a metal patch with a resistive film, and the middle layer is covered with a metal patch. The thickness of the absorber structure is only 0.5 mm, and the absorber can be perfectly attached to the trihedral corner reflector (TCR) without affecting the characteristics of the reflector. By laying the absorber on the TCR, the TCR is stabilized at 8–40 GHz in the range of the incident angle ±20°, and the radar cross-section (RCS) reduction value of the TCR fluctuates around 1 dBsm. Thus, the RCS values of the three frequency points of 10 GHz, 15 GHz, and 35 GHz are consistent to achieve the accurate regulation of RCS. The stability of the absorber at different frequencies can be achieved, which is essential for the precise RCS regulation of complex scatterer structures. The effectiveness of the method was verified in experiments using a TCR metamaterial absorbing unit with resistive film. [ABSTRACT FROM AUTHOR]

The combination of superelastic shape memory alloy fibers and ECC materials can form a new SMA fiber reinforced ECC composite material (SMAF-ECC) with good self-centering performance. In order to study the self-centering performance of the new composite material, 6 groups of pre-notch beam specimens were made for three-point bending cyclic loading tests, and the failure phenomenon, hysteresis curve, self-centering effect and influencing factors of the specimens were analyzed. The research results show that when the SMA fibers are effectively anchored in the ECC matrix, the SMA fibers can exert the superelastic properties to provide the ECC beams with recoverying force, and realize the crack self-closure and deflection self-recovery function for the beams, with the minimum residual crack width and deflection is only 0.9 mm and 1.3 mm respectively. Increasing fiber content can cause a small increase in the self-centering ability of the beams. However, only when the fiber diameter is appropriate, better self-centering effect can be achieved, but the difference caused by fiber diameter in the test was only 5%. SMA Fiber end forms have significant influence on self-centering performance. The knotted end beam can get a more than 70% self-centering ratio, while the straight end beams and bended end beams have no self-centering ability. The research results provide important reference for the research and application of this new self-centering materials and their structures. [ABSTRACT FROM AUTHOR]

It has been partially shown that salicylic acid (SA) as an imprinting molecule can produce better photocatalytic effect, while the contribution of SA as a molecular imprinting and degradation substrate is not clear. Herein, SA-TiO2 was prepared by a one-step molecular imprinting method using SA as the imprinting molecule and tetra-n-butyl titanate as the precursor, which was analyzed by XRD, UV–Vis, SEM, TEM-EDS, XPS, PL, FT-IR, EIS, and photocurrent response. The results shown that 1.5SA-TiO2 had the best electrochemical properties and therefore the best photoelectric effect. Moreover, the decolorization rates of SA within 30 min were 49.25% and 62.69% for TiO2 and SA-TiO2, respectively, indicating that the synthesized SA-TiO2 had better photocatalytic performance and could be applied in future scenarios for the efficient degradation of SA wastewater. [ABSTRACT FROM AUTHOR]

In order to understand the heavy metal content and health risk level in water of kasrt cave in Libo, Guizhou Province, the concentration of 8 heavy metals in water from 13 caves was analyzed and detected, and the health risk assessment model recommended by US EPA was used to estimate the health hazard risk level of heavy metal pollutants in drinking water. The results showed that the average concentration of heavy metals is Zn>Cr>Cu>As>Ni>Cd>Pb>Hg, which did not exceed the class III water standard of Quality Standard for Ground Water (GB/T 14848-2017). The content of heavy metals in cave water in Libo is generally lower than (or only a little close to) surface water and groundwater outside the cave. Spearman correlation analysis showed that Zn was significant positive correlation between Pb and Cu, Cd was significant positive correlation with Hg, As was significant negative correlation with Cr and Hg. The health risk assessment showed that the mean values of the total health risk of adults and children caused by heavy metals in cave water were Cr>As>Cd>Cu>Hg>Ni>Pb>Zn. The average annual health risk for both adults and children caused by Cr and As (85% of caves) exceed the maximum acceptable risk for the Swedish Environmental Protection Agency, the Dutch Construction Environmental Protection Agency and the Royal Society of the United Kingdom. This indicates that drinking cave water for a long period of time may lead to a certain risk of carcinogenesis. The average contribution rate of Cr and As to the total health risk of adults and children is 99.60%, so Cr and As should be regarded as the priority control and management of pollutants of cave water in Libo. The total health risks of adults and children were 4.80x10-6~3.51x10-5 a-1 and 5.46x10-6~3.97x10-5 a-1, respectively, indicating that children are more sensitive risk receptors than adults, and the control and management of children's drinking water safety should be strengthened. [ABSTRACT FROM AUTHOR]

The experimental and shear strength analytical investigations carried out on seismic-damaged steel reinforced concrete (SRC) columns strengthened with enveloped steel jacket subjected to cyclic loading are presented in this paper. Four 1/2-scale SRC columns were designed and manufactured and the postearthquake damage, enveloped steel jacket-confined, and destructive tests were carried out under lateral cyclic loading. The effects of postearthquake damage degree and enveloped steel jacket-confined on shear capacity and ductility capacity were all well examined. Test results indicate that the ductility of seismic-damaged SRC columns strengthened with enveloped steel jacket increases with the reduction of the postearthquake damage degree. The results indicate that the calculation formula of shear bearing capacity of SRC columns is feasible. Based on GB50010-2010, ACI318-08, and CSA-04, three different shear models were established, and the calculated values of shear capacity are quite different, and the analysis of the shear strength of RC in the strengthened seismic-damaged SRC column cannot be ignored. The formula is verified, and the calculated results are consistent well with the experimental results. [ABSTRACT FROM AUTHOR]

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto the tubes. Static-loading tests were conducted to study the compression behavior of square thin-walled CFST columns with steel bar stiffeners placed inside or outside the tube. The effect and feasibility of steel bar stiffeners were studied through the analysis of failure mode, load–displacement relationship, ultimate load, ductility, and local buckling. Different setting methods of steel bars were compared as well. The results showed that steel-bar stiffeners proposed in this paper can be effective in delaying local buckling as well as increasing the bearing capacity of the columns, but will decrease the ductility of the columns. In order to obtain a higher bearing capacity of columns, steel bars with low stiffness should be placed inside and steel bars with high stiffness should be placed outside of the steel tubes. The study is helpful in providing reference to the popularization and application of this new structural measure to avoid or delay the local buckling of thin-walled CFST columns. [ABSTRACT FROM AUTHOR]

Gonggan' (Citrus reticulata) is a famous, high-quality and special citrus cultivar in the Xijiang River valley, Guangdong Province. However, it easily suffers from postharvest diseases, and thus is not tolerant to storage. Based on the preliminary test results, prochloraz-manganese chloride complex was selected as the disinfectant, and prepared into different concentrations for carrying out preservation test by dipping fruits. The fruit weight loss, soluble solids content and decay rate were analyzed, and the application security and sensory evaluation for fruit freshness and flavor were observed. The results showed that dipping fruits with prochloraz-manganese chloride complex solution had significant preservation effect on 'Gonggan' fruits in postharvest storage; the suitable concentration was 2.0 - 3.0 g / L, and the decay rates of fruits stored at room temperature for 30, 60 and 90 d were below 5%, 10% and 15%, respectively. Plate inoculation test further revealed that the pathogen of 'Gonggan' was sensitive to prochloraz-manganese chloride complex, and the concentration of 1.0 g/L was enough to produce significant antimicrobial effect. Other technical links related to postharvest preservation of 'Gonggan' with prochloraz-manganese chloride complex were discussed. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to solve the weakness of heavy postharvest diseases and non-endurable storage of 'Shatangju' , to improve the preservation effect of 'Shatangju'. [Method] Fruits were dipped in different concentrations of prochloraz-manganese chloride complex solutions. The postharvest weight loss rate, soluble solids content and decay rate of fruits wrere determined, and the safety of chemical agents was observed and evaluated. [Result] Prochloraz-manganese chloride complex had significant preservation effect on postharvest 'Shatangju' fruits, and the appropriate concentration was 0. 15%-0.20% (effective content) ; the decay rates of fruits stored at room temperature for 15 , 30 , 45 , 60 and 90 d wereO, 5% , < 10% , < 10% and <30% ; there was no specific changes in smell and flavor of non-decayed fruits. [Conclusion] Prochloraz-manganese chloride complex solution had significant preservation effect on ' Shatangju ' by inhibiting and reducing the growth and development of pathogenic bacteria, and the effect was much belter under refrigeration condition. [ABSTRACT FROM AUTHOR]

Lou-temperature stress is a major abiotic stress influencing plant growth, economic yield and quality worldwide. Precise and reliable identification and test of plant cold resistance is a foundation for exploring low-temperature damages, cold resistance mechanism of plants, cultivating and innovating quality cold-resistant germplasm resources, which is rather important for woody plants because their perennial and large-sized characteristics. Generally, most researches on plant cold-resistant physiology focused on identification and utilization of cold resistance worldwide, and a few on test methods of cold resistance, but cold resistance mechanism has been less reported. Therefore, researches on methods of identifying and testing plant resistance have achieved considerable progress, accumulated much experience and formed characteristics gradually in terms of methodology. Current methods of identifying plant cold resistance include open field/outdoor cultivation evaluation, cold and frost damage investigation, simulated cold weather, and mathematical model forecast. And the methods of testing plant cold resistance include growth condition test, frozen index investigation, electrolyte leakage, bioelectrical impedance mapping and so on. Synthesizing the methods of identifying and testing plant cold resistance should be a key matter in the present and future researches and application of plant cold resistance physiology, improvement and innovation of the identification and test will be an important direction of the future researches. Identification and test of plant cold resistance based on genomics, meta-bonomics and proteomics should be the new trend of the researches on physiology and ecology of plant cold resistance. [ABSTRACT FROM AUTHOR]

In order to study the seismic behavior of CFRP-reinforced seismic-damaged joints in composite frame consisting of concrete-filled square steel tubular (CFSST) columns and steel beams, four one half scaled models of exterior joints in composite frame consisting of CFSST columns and steel beams were designed and manufactured. The test consisted of pre-damage loading, rehabilitation with CFRP and destruction tests under lateral cyclic loading. The effectiveness of CFRP-strengthened seismic-damaged joints and the reinforcement effect on different levels of seismic damage were studied. Based on the test data, the hysteretic loops, skeleton curves, the CFRP strain, ductility, dissipative ability, ultimate strength and stiffness degradation, etc. were obtained. Results show that CFRP-strengthened seismic-damaged exterior joints in composite frame consisting of CFSST columns and steel beams meets the strong column-weak beam requirement of seismic design, and the failure modes of all joints are bending failure of beam. The reinforcement with CFRP has a significant on increasing the ultimate capacity and the seismic behaviors of the joints. The study indicates the rehabilitated joints can reach or even exceed the level of their original seismic performances before seismic damage in a certain extent of damage level. [ABSTRACT FROM AUTHOR]

Propagation and cultivation results showed that grafting southern highbush blueberry cultivar ʽSharpblueʼ taking Wufanshu ( Vaccinium bracteatum Thunb.) as rootstock has much high survival rate, and inlaid bud-grafting and one-bud cut-grafting were both suitable for application. The grafted blueberry saplings integrated the excellent biological traits of rootstock species and scion cultivar, growth vigor was markedly stronger than that of the same-aged none-grafted blueberry in field planting. Further more, early bearing and productivity and fruit quality of grafted blueberry were also significantly improved. Grafting is a practical and efficient technology innovation in blueberry production. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) photocatalysis is a popular and promising technology in water treatment, but the performance evaluation usually depends on expensive equipment. In this study, using a smartphone for colorimetric detection, a self-invented method based on paper and microtubes (PMTs) is proposed to test the photocatalytic performance of TiO2. Firstly, the study has identified that PMTs achieved a correlation coefficient of above 0.9 between the greyscale values and concentrations during the physical process of different color dyes (i.e., rhodamine B (RhB), reactive yellow (RY), methylene blue (MB), and mixtures of the two or three dyes). The results indicate that when the principle of solution color follows the CMYK (Cyan, Magenta, Yellow, Black) color model, its photo color on white paper background conforms to the RGB (Red, Green, Blue) color model. Compared to the results obtained from the absorbance method, the PMTs method showed high reliabilities up to 99.36% on the monitoring of the photocatalytic process of the different dye solutions. Interestingly, the colorless solution of salicylic acid (SA) could also be analyzed by the PMTs after complexed with Fe(III) ion to develop a purple solution. These results suggest that the PMTs could be an alternative analysis method to evaluating physical and chemical reaction processes when the high-tech analysis equipment is unviable. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tubular columns have been studied extensively worldwide. Such columns provide stable energy dissipation, which is ideal for earthquake engineering application. However, most applications use rectangular steel tubular sections. In the location of wall intersections, these sections often create sharp corners, which are architecturally displeasing. In some facilities such as schools and correctional facilities, sharp corners are even prohibited due to their potential hazard to occupants. To resolve the issue, concrete-filled crisscross steel tubular columns (CCSTCs) have been proposed. Three half-scaled specimens were constructed and tested under cyclic displacement loading history. The experimental results were used to calibrate numerical models of the components and further used to examine the seismic behavior of a three-story prototype office building located in Los Angeles. The results showed the proposed CCSTC has excellent energy dissipation and postearthquake performance, and hence it can be used as an alternative lateral force resisting system for seismic applications. [ABSTRACT FROM AUTHOR]

To study the seismic behavior of unsymmetrical steel reinforced concrete column, cyclic loading tests were carried out on 12 columns with T-shaped section steel and 12 columns with L-shaped section steel. The test parameters included shear span ratio, axial compression ratio, stirrup ratio and presence of cross tie. Mechanical process, failure mode, hysteretic characteristics, skeleton curves, ductility and energy dissipation ability were taken into comparison. The result indicates that unsymmetrical steel reinforced concrete column possesses good seismic performance under constant axial compression and cyclic horizontal load. The failure modes include bonding failure, shear-bond failure, shear compression failure and shear-composition failure. Obvious asymmetry phenomenon of positive and negative hysteresis loop are shown. The span ratio has great influence on failure mode and shear-composition failure usually takes place in L-shaped steel section column. With the increase of axial compression ratio, the ductility decreases, which is obvious in L-shaped steel section column. The ductility and bearing capacity of the T-shaped steel section columns are improved greatly with the increase of stirrup ratio, but not obvious for T-shaped steel section column with smaller span ratio. Cross ties can improve bearing capacity, limit strength and stiffness degradation and enhance deformation capacity of L-shape steel section columns clearly. [ABSTRACT FROM AUTHOR]

The paper microzones method (PMZs) is a green chemical method that uses the principle of the three primary colors of red, green and blue (RGB) to detect the water quality of the droplets on white paper. However, this method is rarely used in the performance evaluation of photocatalysts. The paper details the first use of paper microzones utilized in the evaluation of photocatalyst performance. A sol-gel method was used to prepare molecularly imprinted modified TiO 2 photocatalysts for the treatment of different wastewaters, and characterized the catalysts using XRD and several other methods. The reliability of PMZs on the evaluation of photocatalytic activity and selectivity was also analyzed. The following results were obtained: EP-TiO 2 catalysts (EP, ethyl paraben, the imprinting molecule) with different S doping levels were synthesized using a one-step sol-gel method, and the best S doping ratio was found to be n(Ti):n(S) 3:1. S-EP-TiO 2 was found to be 100% anatase and showed excellent photocatalytic performance, while the PMZs method accurately determined changes in RGB levels for the photocatalytic degradation process of pollutants using S-EP-TiO 2 as the photocatalyst. A photocatalytic kinetic analysis showed the PMZs method was quite suitable for the evaluation of photocatalyst activity, but the evaluation of selectivity needs improvement. This method is a promising green chemistry way to evaluate photocatalyst performance and the rapid detection of outdoor sewage water quality. [Display omitted] • Innovative application of Paper microzones in the evaluation of photocatalytic performance. • Paper microzones method is compared with the traditional spectroscopic method. • Simple operation and green chemistry for environmental research. [ABSTRACT FROM AUTHOR]

This paper reports a study of the effects of different concealed bracing materials on the seismic performance of short-legged shear walls and presents the results of low-frequency cyclic loading tests on three L-shaped short-leg shear walls—one wall without concealed bracing and the other two with concealed bracing materials of steel bars and SMA bars, respectively. The tests were aimed mainly at analyzing the effects of different concealed bracing materials on seismic performance indicators such as crack pattern, bearing capacity, ductility, hysteresis performance, stiffness, and energy dissipation of the L-shaped short-leg shear walls. The results revealed that their seismic performance with concealed bracing was better than without concealed bracing. The short-leg shear walls with SMA bar concealed bracing had the lowest number of cracks and the smallest crack width, and the effect of delaying the development of cracks was more evident. The short-leg shear walls with steel reinforcement and SMA-bar concealed bracing were better in bearing capacity, ductility, and energy dissipation capacity, with, respectively, 11% and 26.3% increase in ultimate load, 4% and 18.6% increase in ultimate displacement, and 12% and 28% increase in energy dissipation. It can be seen that setting concealed bracing effectively enhances the seismic performance of short-leg shear walls, and that short-leg shear walls with concealed SMA bar bracing have the most significant improvement in seismic performance. • The low-frequency cyclic loading tests on three L-shaped short-leg shear walls with different concealed bracing materials were conducted. • The effects of different concealed bracing materials on seismic performance indicators of the L-shaped short-leg shear walls were explored. • The short-leg shear walls with concealed SMA bar bracing have the most significant improvement in seismic performance. [ABSTRACT FROM AUTHOR]

Little is known about the bioaccumulation and trophic transfer of total mercury (THg) and methylmercury (MeHg) via food webs in terrestrial ecosystems, especially in subtropical forest ecosystems. In the present study, THg and MeHg were determined as well as the carbon (δ13C) and nitrogen (δ15N) isotope composition in samples of soils, plants, invertebrates, and songbird feathers to construct food webs in a remote subtropical montane forest in Mt. Ailao, southwest China and assess the bioaccumulation, biomagnification, and trophic transfer of Hg. Results showed that the trophic levels (TLs) of all consumers ranged from 0.8 to 3.3 and followed the order of songbirds > spiders > omnivorous insects > herbivorous insects > plants, and THg and MeHg exhibited a clear biomagnification up the food chain from plants-herbivorous/omnivorous insects-spiders-songbirds. The lowest MeHg concentration was observed in pine needles ranged from 0.104 to 0.949 ng g−1 with only a 1.6% ratio of MeHg to THg (MeHg%), while the highest MeHg concentrations ranged from 425 to 5272 ng g−1 in songbirds with MeHg% values of up to 96%. High values of trophic magnification slope (TMS) for THg (0.22) and MeHg (0.38) were observed in plant-invertebrate-songbird food chain, verifying the significant bioaccumulation of Hg, particularly MeHg, in the remote subtropical forest ecosystem. This study confirmed the production and efficient biomagnification of MeHg in remote subtropical montane forest and the significant bioaccumulation of MeHg in terrestrial top predators. [Display omitted] • THg and MeHg increased with trophic positions in forest food webs. • THg exceeded adverse effect thresholds in insectivorous songbirds. • MeHg significantly biomagnified in subtropical forest food webs. Significant biomagnification of methylmercury exists in a remote subtropical forest food web. [ABSTRACT FROM AUTHOR]

Floroniahuishuiensis Zhou & Xu, sp. nov. (♂♀) is the first species in the genus Floronia to be described from Baiyan Cave in Guizhou Province, China. The new species is similar to F.zhejiangensis Zhu, Chen & Sha, 1987 but differs in structural details of the genital organs, primarily by the presence of a well-developed retrolateral tibial apophysis, a hook-shaped distal end of the radix in the male palp, and the rectangular posterior median plate in the epigyne. The illustration of copulatory organs of F.bucculenta (Clerck, 1757) and F.zhejiangensis Zhu, Chen & Sha, 1987 were reproduced here for comparison. A detailed description, photographs of the habitus and copulatory organs of the new species and a distribution map is provided., Competing Interests: The authors have declared that no competing interests exist., (Guchun Zhou, Weifeng Du, Chengxiang Xu, Muhammad Irfan.)