Increased dependence on nitrogen-fixation of a native legume in competition with an invasive plant

Suppression of roots and/or their symbiotic microorganisms,such as mycorrhizal fungi and rhizobia,is an effective way for alien plants to outcompete native plants.However,little is known about how invasive and native plants interact with the quantity and activity of nutrient-acquisition agents.Here a pot experiment was conducted with monoculture and mixed plantings of an invasive plant,Xanthium strumarium,and a common native legume,Glycine max.We measured traits related to root and nodule quantity and activity and mycorrhizal colonization.Compared to the monoculture,fine root quantity(biomass,surface area)and activity(root nitrogen(N)concentration,acid phosphatase activity)of G.max decreased in mixed plantings;nodule quantity(biomass)decreased by 45%,while nodule activity in Nfixing via rhizobium increased by 106%;mycorrhizal colonization was unaffected.Contribution of N fixation to leaf N content in G.max increased in the mixed plantings,and this increase was attributed to a decrease in the rhizosphere soil N of G.max in the mixed plantings.Increased root quantity and activity,along with a higher mycorrhizal association was observed in X.strumarium in the mixed compared to monoculture.Together,the invasive plant did not directly scavenge N from nodule-fixed N,but rather depleted the rhizosphere soil N of the legume,thereby stimulating the activity of N-fixation and increasing the dependence of the native legume on this N source.The quantity-activity framework holds promise for future studies on how native legumes respond to alien plant invasions.

Biology of Hippo signaling pathway:Skeletal muscle development and beyond

Global demand for farm animals and their meat products i.e.,pork,chicken and other livestock meat,is steadily incresing.With the ongoing life science research and the rapid development of biotechnology,it is a great opportunity to develop advanced molecular breeding markers to efficiently improve animal meat production traits.Hippo is an important study subject because of its crucial role in the regulation of organ size.In recent years,with the increase of research on Hippo signaling pathway,the integrative application of multi-omics technologies such as genomics,transcriptomics,proteomics,and metabolomics can help promote the in-depth involvement of Hippo signaling pathway in skeletal muscle development research.The Hippo signaling pathway plays a key role in many biological events,including cell division,cell migration,cell proliferation,cell differentiation,cell apoptosis,as well as cell adhesion,cell polarity,homeostasis,maintenance of the face of mechanical overload,etc.Its influence on the development of skeletal muscle has important research value for enhancing the efficiency of animal husbandry production.In this study,we traced the origin of the Hippo pathway,comprehensively sorted out all the functional factors found in the pathway,deeply analyzed the molecular mechanism of its function,and classified it from a novel perspective based on its main functional domain and mode of action.Our aim is to systematically explore its regulatory role throughout skeletal muscle development.We specifically focus on the Hippo signaling pathway in embryonic stem cell development,muscle satellite cell fate determination,myogenesis,skeletal muscle meat production and organ size regulation,muscle hypertrophy and atrophy,muscle fiber formation and its transformation between different types,and cardiomyocytes.The roles in proliferation and regeneration are methodically summarized and analyzed comprehensively.The summary and prospect of the Hippo signaling pathway within this article will provide ideas for further improving meat production and muscle deposition and developing new molecular breeding technologies for livestock and poultry,which will be helpful for the development of animal molecular breeding.

Effects of T-S wave amplitude on the control of boundary layer transition by streaks

The effects of streaks on boundary layer transition depend on the initial amplitude of T-S waves introduced to excite the transition. This problem was studied in a flat-plate boundary layer in water tunnel by using hydrogen bubble method. Three T-S wave initial amplitudes were tested. The results show that both narrow and wide-spacing streaks depress the transition excited by T-S waves with lower initial amplitude. However, when transition is excited by T-S waves of higher initial amplitude, the narrow-spacing streaks depress the transition, while the wide-spacing streaks promote the transition. Futrther the underlying mechanisms were also analyzed.

Design and experiment of a Chinese chive harvester

Recognizing the labor intensity of current domestic Chinese chive harvesting and the need for its mechanized harvesting,a self-propelled electric Chinese chive harvester is designed.The machine is composed of a control system,supporting mechanism,cutting parts,conveying and clamping mechanisms,frame,and collection system.It can complete Chinese chive feeding,cutting,transmission,and binning operations at one time.It has a cutting width of 0.25 m and wheelbases of 260 mm and 460 mm.Two 12 V,42 Ah lead-acid batteries were used in series as the power supply.The mechanical properties of Chinese chive were analyzed,and shear and compression tests were carried out to determine that the average value of the maximum shear force on the chives is 129 N.Up to a compressive force of 225 N,Chinese chives are not damaged.According to the physical characteristics of Chinese chives and the requirements of the harvesting operations,design and calculation of the key components of the harvester’s transmission mechanism and the strength of the whole machine frame were completed.An embedded control system and Cortex-M3 microprocessor were used to control the harvester and realize its functions of rolling and harvesting while regulating its speed and protecting its motor.Using the Box-Behnken test design method,the machine’s operating speed,cutter speed,and cutter height were selected as influencing factors,and the lodging rate and loss rate were evaluated as a test.A mathematical regression model of influencing factors and evaluation indexes was established to analyze the influence of these factors and indexes and optimize test parameters.The optimal parameter combination is determined to be:operating speed,1.1 km/h;cutter speed,220 r/min;cutter height 2.0 cm.The parameters were verified from field tests and the results showed that under the optimized parameter combination,the average lodging rate was 3.96% and the average loss rate was 3.23%,indicating that the Chinese chive harvester meets the agronomic requirements of Chinese chive harvesting.This harvester could be modified to harvest other crops such as chrysanthemums and Mongolian Chinese chive.

Seismic performance of HWBBF considering different design methods and structural heights

Previous research has shown that using buckling-restrained braces(BRBs)at hinged wall(HW)base(HWBB)can effectively mitigate lateral deformation of steel moment-resisting frames(MRFs)in earthquakes.Forcebased and displacement-based design methods have been proposed to design HWBB to strengthen steel MRF and this paper comprehensively compares these two design methods,in terms of design steps,advantages/disadvantages,and structure responses.In addition,this paper investigates the building height below which the HW seismic moment demand can be properly controlled.First,3-story,9-story,and 20-story steel MRFs in the SAC project are used as benchmark steel MRFs.Secondly,HWs and HWBBs are designed to strengthen the benchmark steel MRFs using force-based and displacement-based methods,called HWFs and HWBBFs,respectively.Thirdly,nonlinear time history analyses are conducted to compare the structural responses of the MRFs,HWBBFs and HWFs in earthquakes.The results show the following.1)HW seismic force demands increase as structural height increases,which may lead to uneconomical HW design.The HW seismic moment demand can be properly controlled when the building is lower than nine stories.2)The displacement-based design method is recommended due to the benefit of identifying unfeasible component dimensions during the design process,as well as better achieving the design target displacement.

Flexural behavior of high-strength,steel-reinforced,and prestressed concrete beams

To study the flexural behavior of prestressed concrete beams with high-strength steel reinforcement and high-strength concrete and improve the crack width calculation method for flexural components with such reinforcement and concrete,12 specimens were tested under static loading.The failure modes,flexural strength,ductility,and crack width of the specimens were analyzed.The results show that the failure mode of the test beams was similar to that of the beams with normal reinforced concrete.A brittle failure did not occur in the specimens.To further understand the working mechanism,the results of other experimental studies were collected and discussed.The results show that the normalized reinforcement ratio has a greater effect on the ductility than the concrete strength.The cracking-and peak-moment formulas in the code for the design of concrete(GB 50010-2010)applied to the beams were both found to be acceptable.However,the calculation results of the maximum crack width following GB 50010-2010 and EN 1992-1-1:2004 were considerably conservative.In the context of GB 50010-2010,a revised formula for the crack width is proposed with modifications to two major factors:the average crack spacing and an amplification coefficient of the maximum crack width to the average spacing.The mean value of the ratio of the maximum crack width among the 12 test results and the relative calculation results from the revised formula is 1.017,which is better than the calculation result from GB 50010-2010.Therefore,the new formula calculates the crack width more accurately in high-strength concrete and high-strength steel reinforcement members.Finally,finite element models were established using ADINA software and validated based on the test results.This study provides an important reference for the development of high-strength concrete and highstrength steel reinforcement structures.