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Foxtail millet (Setaria italica L.) is one of the most economically valuable drought-resistant crops in arid and semi-arid regions as a nutrition health crop, which has garnered considerable research attention. We evaluated the effects of replacing chemical nitrogen fertilizers with organic fertilizers on two primary plant accessions of foxtail millet (Dungu and Jinfen no. 2). Nitrogen in a standard fertilizer was replaced with organic fertilizer at application levels of 0, 25, 50, 75, and 100%, with effects on crop yield, quality (appearance, taste, and nutritional value), and soil microbiome, assessed using field cultivation experiments. Our results indicate that partial replacement of conventional fertilizers with organic fertilizers improved both yield and quality. Specifically, the 75% replacement significantly improved the appearance (yellow pigment content and grain diameter) and taste (amylose content and soluble sugar content) of foxtail millet, while the 50% replacement significantly improved the taste (gel consistency) and nutritional qualities (crude protein content and seven amino acids’ content). The 50% replacement of organic fertilizer regulated amino acid content more significantly than starch content. Increased ratios of organic fertilizer significantly reduced the soil pH by 0.03–0.36 and increased the relative abundance of Chloroflexi as well as that of Basidiomycota and Cercozoa in the soil microbiome. Our findings provide a solid theoretical foundation for subsequent studies on fertilizer use for foxtail millet and contribute to developing functional nutritional foods in the foxtail millet industry.

CFRP tendons with smooth surface conditions have good applicability in prestressed structures and structural reinforcement because of their high load-carrying capacity and simple production. However, they are difficult to anchor reliably. This paper developed an improved wedge-type anchor for large-diameter CFRP tendons. The mechanical behavior analysis theories of wedge-type anchors, including the load-carrying capacity evaluation model, were presented. The friction behavior of the sand-coated sleeve-tendon, which was used to evaluate the load-carrying capacity of the anchor, was experimentally investigated. The influence laws of the main wedge-type anchor parameters on the mechanical behavior of the anchor were obtained through theoretical analysis. Then, the optimal anchorage system design method was proposed, and the optimal anchor designs for smooth CFRP tendons with various diameters were presented. The anchor performance was experimentally evaluated, and the sleeve-tendon interface friction coefficient was approximately doubled after optimization, reaching 0.475. The wedge and barrel cone angles, preset load and anchor length had significant effects on the mechanical behavior of the anchor. The optimal design anchors for smooth CFRP tendons with diameters of 10 mm and 12.7 mm and spiral-wrapped CFRP tendons with diameters of 10 mm reached failure loads up to 93.8, 91.2 and 95.4% of the tensile capacity of the tendons, respectively.

In this study, the safe critical temperature that can be tolerated by CFRP tendons under normal working conditions was derived through tensile tests at room and high temperatures. Next, the times required to reach a safe critical temperature for CFRP cables protected with different types of fire-retardant materials of various thicknesses were determined through fire resistance tests, Finally, fitting the surface of the finite element simulation results allowed the establishment of the temperature rise calculation model of CFRP tendons under the protection of fire-retardant materials. The results showed that 300 °C can be regarded as the safe critical temperature. Both high-silica needled felt and ceramic fiber felt exhibited high fireproof performance. With an increase in the thickness of the fire-retardant material, the time for the CFRP tendon to reach the inflection point of the heating rate increased, and the safe fire resistance time increased exponentially. According to the HC temperature rise curve, the fire resistance time of CFRP tendons protected by 24 mm thick high-silica needled felt was 45 min, and that for CFRP tendons protected by 24 mm thick ceramic fiber felt was 39.5 min. Under the action of fire corresponding to the hydrocarbon temperature rise model, the safe fire resistance time of CFRP tendons protected by 45 mm high-silica needled felt or 50 mm ceramic fiber felt was more than 2 h, sufficient to meet the specification. The proposed model of fire resistance performance enables the determination of the thickness of the fire resistance material required to obtain different degrees of fire resistance for CFRP cables for structural use.

To expand the application scope of prestressed carbon fiber-reinforced polymer (CFRP) cables in civil engineering, the ultimate tensile strength of these cables was tested and evaluated under bending conditions. First, the study analyzed the tensile failure mechanism of CFRP cables under bending conditions based on elastic bending analysis theory. Thereafter, the ultimate stress state of individual tendons and cables was derived and a calculation model for the tensile strength of bent CFRP cables was established. Second, 14 sets of test conditions were created for CFRP cables under bending angles of 20–40° and bending radii of 1.5–3 m. Then, bending tensile tests were conducted to evaluate the effects of the above factors on the ultimate tensile strength, and the correctness of the computational model was verified using experiments. Finally, the ultimate performance of CFRP cables was theoretically predicted using the established model. The results showed that the cable bending tensile strength was associated with the radius r, tensile strength f, and elastic modulus E of the reinforced material and the bending radius R, but was not correlated with the interface buffer material or the bending angle of the steering system. Moreover, the flexural tensile residual strength was only affected by R/r and E/f. When E/f involved conventional material parameters, the residual strength increased nonlinearly with increased R/r. When R/r ≥ 600, the residual strength reached more than 80%. Therefore, R/r at 600 could be used as the design basis for a safe critical radius.

This paper aimed to study the electrical and mechanical performances of carbon nanofibers (CNFs) mortar. In this research, quartz sand was used as aggregate. The dosage of CNFs ranged from 0 to 2.4% by volume of cement, and water–cement (w/c) ratio in this study was 0.35. Electrical resistance of CNFs mortar was tested with curing time from 1 to 28 days. In addition, the flexural strength, the compressive strength and the piezoresistivity of CNFs mortar with monotonic compressive loading and cyclic compressive loading after curing for 28 days were determined. Results indicated that CNFs volume (V) of 0.3–1.8% was the percolation zone of CNFs mortar with quartz sand. When CNFs volume was in the percolation zone, the resistance decreased obviously; meanwhile, the resistivity of CNFs mortar was in a linear function of V−1/3. Moreover, the resistance of CNFs mortar with CNFs dosages of 0–1.8% tended to increase with curing time. While, as CNFs content ranged from 1.8 to 2.4%, the resistance had little change with curing time. When CNFs contents were 0.6% and 1.2%, respectively, the samples performed the optimal mechanical strengths and piezoresistive property. CNFs mortar with quartz sand presented more sensitive than CNFs mortar with river sand under monotonic compressive loading and cyclic compressive loading.

The epoxy resin used as a load-transfer medium (LTM) to fill the bond-type anchors of carbon fiber reinforced polymer (C225FRP) will creep under three-dimensional compressional conditions, thereby decreasing the carrying capacity of the anchorage. In this paper, a shear stress distribution model is proposed for the tendon–LTM bonding interface in the anchorage zone of CFRP tendon bond-type anchors. Based on this distribution model, a model for evaluating the load-carrying capacity of such anchorages is established after considering LTM creep. Creep deformation data were obtained via model tests of an anchorage epoxy resin LTM subjected to three compressive magnitudes of stress under lateral restraint conditions for 3 years. The influence of LTM creep on the load-carrying capacity of the anchors is evaluated, and theoretical methods for eliminating the negative effect of the LTM creep of the anchor were proposed. The two load-carrying capacity prediction models established before and after considering LTM creep were verified by experiments. The experimental results pertaining to load-carrying capacity are in good agreement with the theoretical prediction; the creep strain of the LTM will reach 0.004 and 0.038 under axial compressive stresses of 50 MPa and 250 MPa, respectively, and lateral restraint conditions. LTM creep will lead to an obvious reduction in the radial compressive stress of the bonding interface, and the loss of the load-carrying capacity of the anchorage can reach 12%. Increasing the axial preset load acting on the LTM or extending the length of the anchor can counteract the adverse effects of creep.

An approach based on continuum damage mechanics (CDM) is applied to predict the fatigue life of welded joints with artificial corrosion pits. Full penetration load-carrying fillet cruciform welded joints with a 45° inclined angle were constructed, and artificial corrosion tests and fatigue tests of the welded joints were carried out. A new damage variable based on the crack size was defined to assess the stiffness degradation. Material parameters in the damage evolution equations were obtained from the fatigue experimental data. The CDM model combined with numerical simulations was used to describe the fatigue damage evolution process. A comparison between the fatigue life predicted results and the test results was made. The results show that fatigue life decreases with the increase of pit depth, decreasing by approximately 50% from d = 0 mm to 2 mm at the same stress range. The fatigue damage curves can be divided into three stages: the crack initial growth stage (D 0.8). The fatigue damage curves for different stress ranges are nearly the same under the same pit depth. In addition to the material and loading conditions, the corrosive environment also has an effect on the material parameters in the fatigue damage evolution process. The fatigue life predicted results agree well with the test results, and the maximum relative error is 10.6%. The crack size can be used to describe the fatigue damage evolution of welded joints with artificial corrosion pits.

To explore the effects of biogas slurry coordinating chemical fertilizer on growth promotion of tomato, we used three kinds of typical biogas slurry as concentrated nutrient solution, respectively fermented from raw duck manure, pig manure, cow dung, while urea, monocalcium phosphate and potassium sulphate as auxiliary nutrition to balance the nutrient difference between different dilution ratios of biogas slurry. The results showed the biogas slurry partially substituting chemical fertilizer could significantly improve soil fertility, including available nitrogen, phospho-rus, and potassium. As for water soluble calcium, magnesium, iron, manganese and zinc in soil, biogas slurry application could activate their availability, with the magnitude of such effects depended on the fermentation level of raw materials and dilution ratio. Compared with chemical fertilizer, coordinating biogas liquid fertilizer significantly promoted the growth of tomato, with the yield increased by 55.9%-232.8% and the chemical fertilizer dosage decreased by 18.2%-85.0%. Furthermore, such effects became more prominent along with prolonged time. The fruit quality was significantly improved with the increases of lycopene, ascorbic acid and total sugar, and the decreases of acidity and nitrite concentration, and the decrease of NO为探索沼液和化肥协同促生的效果,以3种常见禽畜粪便(鸭粪、猪粪、牛粪)作为发酵原料的沼液为母液,以氮磷钾镁肥作为化学肥料辅助,平衡不同稀释比例之间的养分差异,研究沼液配施对番茄生长发育的影响. 结果表明: 沼液部分替代化肥可以显著改善土壤速效氮、磷、钾的肥力状况,依发酵原料和稀释比例不同,沼液对土壤水溶性钙、镁和有效铁、锰、铜、锌有不同程度的活化作用. 与完全施用化肥相比,沼液配施化肥可显著促进番茄生长,且随生育期的延长,沼液的促生作用愈发凸显,最终增产幅度达55.9%～232.8%,化肥用量减少18.2%～85.0%;番茄果实品质显著改善,番茄红素、Vc、总糖含量均显著提高,果实酸度显著降低,NO

To overcome the drawbacks of bond-type anchors for carbon fiber–reinforced polymer (CFRP) cables, an innovative bonded anchor with steel wedges at the free end is developed in this study. T...

In order to investigate the strengthening effect of carbon fiber reinforced polymer (CFRP) on the fatigue performance of cracked cruciform welded joints, numerical analyses and fatigue tests were presented. Considering the effects of initial crack depth, CFRP modulus, and CFRP thickness, three different methods were employed to assess the SIF ranges of unrepaired and CFRP sheets repaired cruciform welded joints, and a new formula to calculate the SIF range was fitted via numerical results. Two different welding residual stresses obtained from literatures were taken into account to evaluate the effective SIF range. Fatigue life predicted results were determined via the modified Paris equation considering two different crack closure factors. The results demonstrate that the SED method can be successfully and conveniently used to estimate the SIF range, the accuracy of the new equation is verified. CFRP sheets can decrease the SIF range of the crack tip and extend the fatigue life, and the maximum increase in the fatigue life reaches 66%. The effect of different CFRP sheets is nearly the same owing to a small stiffness ratio. Fatigue strength of cracked cruciform welded joints strengthening with CFRP sheets at 2 million cycles increases by 26% compared to that of specimens without CFRP. Good agreement with experimental results indicates that the residual stress B and the Schijve model are recommended to predict the fatigue life of cruciform joints.

Nitric oxide (NO) is a well-known signaling molecular that plays a significant role in stress tolerance of plants to heavy metals. However, the detoxification mechanism of NO has not been well studied. Here, we examined the absorbing and transporting characteristics of copper (Cu) and cadmium (Cd) in tomato seedlings through nutrient solution culture and its response to exogenous NO under Cu and/or Cd stress. Results showed that Cu and Cd with the concentration of 50Mgr;mol·L一氧化氮(NO)作为信号分子,在抵御重金属胁迫中起重要作用,但对不同离子胁迫下的解毒机制尚缺乏研究.本研究采用营养液培养法,研究了铜(Cu)、镉(Cd)单一或复合胁迫下,番茄幼苗对Cu、Cd的吸收转运特性及对外源NO的响应机制.结果表明: 50 μmol·L

Based on the long-term field fertilization experiment in yellow fluvo-aquic soil, this study selected 2 types of soil physical, 8 items of soil chemical, and 5 soil biological properties for principal component-cluster analysis to valuate comprehensively effects of long-term fertilization on soil fertility. Results showed that significant differences of soil properties were found among the fertilization treatments. Compared with no organic manure treatment (NPK), all treatments of organic manure (M) or its combination with inorganic fertilizers (MN, MNP, MNPK) significantly reduced soil bulk density, and increased soil total porosity, the contents of soil organic carbon, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, microbial biomass, and activities of catalase, urease, alkaline phosphatase and invertase. Two principal components that could reflect 85.5% of the original information quantity without losing any original variables were extracted from the initial 15 indices. Within the primary group of principal components, bulk density, total porosity, organic matter, total nitrogen, alkali-hydrolyzable nitrogen, total phosphorous, available phosphorus, available potassium,microbial biomass, catalase, urease, alkaline phosphatase and inver-tase were the major contributors, while among the secondary group of principal components, total potassium and pH were the major ones. Hierarchical cluster analysis of the new indices extracted based on scores of the two principal components revealed the effects of different patterns of long-term fertilization displayed an order of MNPK＞MNP＞M, MN＞NPK＞N, NP＞CK. In conclusion, organic fertilizer has the positive effect on improving soil fertility, and combined application of organic and N, P, K fertilizer is the best fertilizing model.依托黄潮土35 年长期定位试验,以2种土壤物理肥力指标、8种土壤化学肥力指标和5种土壤生物肥力指标进行主成分分析,最后将各主成分得分系统进行聚类分析.结果表明: 不同施肥方式对土壤肥力指标影响显著.施用有机肥处理(M、MN、MNP、MNPK)与NPK处理相比,土壤容重显著降低,而土壤孔隙度、有机质、全氮、碱解氮、全磷、有效磷、微生物生物量和过氧化氢酶、脲酶、碱性磷酸酶活性均显著增加;通过主成分分析可将原15个土壤指标降维,提取出2个主成分,反映了原信息量的85.5%,且无原变量丢失.土壤容重、孔隙度、有机质、全氮、碱解氮、全磷、有效磷、速效钾、微生物生物量、过氧化氢酶、脲酶、碱性磷酸酶、蔗糖酶活性在第1主成分上有较高因子负荷,全钾和pH在第2主成分上有较高因子负荷;以2个主成分得分为新指标进行聚类,得到长期不同施肥方式对黄潮土的培肥效果排序为MNPK＞MNP＞M、MN＞NPK＞N、NP＞CK.可见施用有机肥对黄潮土培肥效果更显著,以有机肥配施氮磷钾化肥方式效果最优.

In order to improve designing and well understanding the working mechanism for fiber reinforced polymer (FRP) tendon wedge anchorage system (FWAS), a theory for solving the anchorage system was presented in this paper. A designing guidelines of anchorage system was established. The theory was checked by comparing the analytical and test results of a Carbon FRP tendon anchrage system. Effect of presetting load and friction coefficient of sleeve-FRP tendon interface on anchorage performance were evaluated by the theory. The results show that, The theory was proved to be correct, it can be used to predict the carrying capacity of FWAS, and it can calculate the stress and transverse displacement of any point of the anchorage system. The presetting load and friction coefficient of sleeve-FRP tendon interface have great impact to anchorage performance.

This paper studied the effects of applying different concentration (0, 0.30, 0.60, and 0.90 mg x kg(-1)) tetracycline on the soil enzyme activities and rape quality. The results showed that soil urease activity after applied 0.30, 0.60, and 0.90 mg x kg(-1) of tetracycline and soil suerase activity after applied 0.90 mg x kg(-1) of tetracycline were inhibited in the whole cultivating period, while the soil sucrase activity after applied 0.30 and 0.60 mg x kg(-1) of tetracycline showed a trend of activation-inhibition-activation. Soil proteinase activity showed a trend of inhibition-activation, and the extent and duration of the inhibition and activation had significant positive correlations with tetracycline concentration (r = 0.950 * *). Soil catalase activity showed activation first and turned to irregular then. The action duration of tetracycline on the activities of soil urease, catalase, sucrase and proteinase were 7 weeks, 6-8 weeks, 7 weeks, and 6-7 weeks, respectively. At harvest time, the soluble sugar contents in rape leaves after applying 0.30, 0.60, and 0.90 mg x kg(-1) of tetracycline decreased dramatically by 91.99%, 87.92%, 90.12%, while the soluble protein content increased by 26.47%, 28.13%, and 23.22%, respectively, compared to the control.