Biomechanical behavior of grass roots at different gauge lengths

Gauge length influences the biomechanical properties of herbaceous roots such as tensile resistance,tensile strength and Young’s modulus.However,the extent to which and how these biomechanical properties of herbaceous roots are influenced remain unknown.To better understand the behavior of roots in tension under different conditions and to illustrate these behaviors,uniaxial tensile tests were conducted on the Poa araratica roots as the gauge length increased from 20 mm to 80 mm.Subsequently,ANOVA was used to test the impact of the significant influences of gauge length on the biomechanical properties,nonlinear regression was applied to establish the variation in the biomechanical properties with gauge length to answer the question of the extent to which the biomechanical properties are influenced,and Weibull models were subsequently introduced to illustrate how the biomechanical properties are influenced by gauge length.The results reveal that(1)the variation in biomechanical properties with root diameter depends on both the gauge length and the properties themselves;(2)the gauge length significantly impacts most of the biomechanical properties;(3)the tensile resistance,tensile strength,and tensile strain at cracks decrease as the gauge length increases,with values decreasing by 20%-300%,while Young’s modulus exhibits the opposite trend,with a corresponding increase of 30%;and(4)the Weibull distribution is suitable for describing the probability distribution of these biomechanical properties;the Weibull modulus for both tensile resistance and tensile strain at cracks linearly decrease with gauge length,whereas those for tensile strength and Young’s modulus exhibit the opposite trend.The tensile resistance,tensile strength,and tensile strain at the cracks linearly decrease with increasing gauge length,while the tensile strength and Young’s modulus linearly increase with increasing gauge length.

Effects of loading rate on root pullout performance of two plants in the eastern Loess Plateau,China

Root pullout performance of plants is an important mechanical basis for soil reinforcement by plant roots in the semi-arid areas.Studies have shown that it is affected by plant factors(species,ages,root geometry,etc.)and soil factors(soil types,soil moisture,soil bulk densities,etc.).However,the effects of loading rates on root pullout performance are not well studied.To explore the mechanical interactions under different loading rates,we conducted pullout tests on Medicago sativa L.and Hippophae rhamnoides L.roots under five loading rates,i.e.,5,50,100,150,and 200 mm/min.In addition,tensile tests were conducted on the roots in diameters of 0.5-2.0 mm to compare the relationship between root tensile properties and root pullout properties.Results showed that two root failure modes,slippage and breakage,were observed during root pullout tests.All M.sativa roots were pulled out,while 72.2%of H.rhamnoides roots were broken.The maximum fracture diameter and fracture root length of H.rhamnoides were 1.22 mm and 7.44 cm under 100 mm/min loading rate,respectively.Root displacement values were 4.63%(±0.43%)and 8.91%(±0.52%)of the total root length for M.sativa and H.rhamnoides,respectively.The values of maximum pullout force were 14.6(±0.7)and 17.7(±1.8)N under 100 mm/min for M.sativa and H.rhamnoides,respectively.Values of the maximum pullout strength for M.sativa and H.rhamnoides were 38.38(±5.48)MPa under 150 mm/min and 12.47(±1.43)MPa under 100 mm/min,respectively.Root-soil friction coefficient under 100 mm/min was significantly larger than those under other loading rates for both the two species.Values of the maximum root pullout energy for M.sativa and H.rhamnoides were 87.83(±21.55)mm•N under 100 mm/min and 173.53(±38.53)mm•N under 200 mm/min,respectively.Root pullout force was significantly related to root diameter(P<0.01).Peak root pullout force was significantly affected by loading rates when the effect of root diameter was included(P<0.01),and vice versa.Except for the failure mode and peak pullout force,other pullout parameters,including root pullout strength,root displacement,root-soil friction coefficient,and root pullout energy were not significantly affected by loading rates(P>0.05).Root pullout strength was greater than root tensile strength for the two species.The results suggested that there was no need to deliberately control loading rate in root pullout tests in the semi-arid soil,and root pullout force and pullout strength could be better parameters for root reinforcement model compared with root tensile strength as root pullout force and pullout strength could more realistically reflect the working state of roots in the semi-arid soil.

A PROPERTY OF HERMITE-PADE INTERPOLATION ON THE ROOTS OF UNITY

We extend a theorem of Ivanev and Saff to show that for the Hermite-Pade interpolant at the roots of unity to a function meromorphic in the unit disc, its leading coefficients vanish if and only if the corresponding interpolani to a related function vanishes at given points outside the unit disc. The result is then extended to simultaneous Hermite-Pade interpolation to a finite set of functions.

Green synthesis,characterization and antimicrobial activity of silver nanoparticles using methanolic root extracts of Diospyros sylvatica

The current research study focuses to formulate the biosynthesized silver nanoparticles for the first time from silver acetate using methanolic root extracts of Diospyros sylvatica,a member of family Ebenaceae. TEM analysis revealed the average diameter of Ag NPs around 8 nm which is in good agreement with the average crystallite size（10 nm）calculated from X-ray Diffraction（XRD）analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram（＋）ve,Gram（-）ve bacterial and fungal strains. The bioinspired Ag-NP showed promising activity against all the tested bacterial strains and the activity was enhanced with increased dosage levels

ON THE EXISTENCE OF GLOBAL GENERAL SOLUTIONS OF POLYNOMIAL SYSTEMS

We discuss the general solutions of polynomial systems in complex domain and prove the existence of global general solutions by applying the generalized Strong Rooted Theorem of complex polynomial systems.