Germination inhibitors detected in Sapium sebiferum seeds

This study identifies endogenous inhibitors of germination associated with seed dormancy in Sapium sebiferum,Chinese tallow.Seed extracts were separated into five distinct fractions(petroleum ether,ether,ethyl acetate,methanol,and aqueous)and tested for their effect on germination of cabbage seeds.There were no significant differences in germination percentages and germination index(GI)between the solvents and the control.The five fractions differentially reduced germination percentage and GI values of cabbage seeds.According to the GI results,the greatest inhibition was with the ether fraction followed by methanol,ethyl acetate,petroleum ether,and aqueous fractions.Gas chromatography–mass spectrometry identified the constituents of the four organic fractions.Compared with the mass spectrum of the National Institute of Standards and Technology library,a compound was confirmed,provided it was more than 85%similar.Analysis of ether extracts identified four compounds:butylated hydroxytoluene(BHT;19.7%),1,2-benzenediol(4.1%),phydroxycinnamic acid,ethyl ester(2.8%),and n-hexadecanoic acid(1.4%).Fourteen,20,and 9 compounds were identified in methanol,ethyl acetate,and petroleum ether extracts,respectively.The IC50 of BHT(the concentration at which BHT inhibits radicle growth by 50%)was 54.8 mg/L,indicating that the presence of BHT might be the primary cause of dormancy in S.sebiferum seeds.

A Method for Assessing Customer Harmonic Emission Level Based on the Iterative Algorithm for Least Square Estimation

With the power system harmonic pollution problems becoming more and more serious, how to distinguish the harmonic responsibility accurately and solve the grid harmonics simply and effectively has become the main development direction in harmonic control subjects. This paper, based on linear regression analysis of basic equation and improvement equation, deduced the least squares estimation (LSE) iterative algorithm and obtained the real-time estimates of regression coefficients, and then calculated the level of the harmonic impedance and emission estimates in real time. This paper used power system simulation software Matlab/Simulink as analysis tool and analyzed the user side of the harmonic amplitude and phase fluctuations PCC (point of common coupling) at the harmonic emission level, thus the research has a certain theoretical significance. The development of this algorithm combined with the instrument can be used in practical engineering.

Orbital Elements Ephemerides and Interfaces Design of LEO Satellites

Low earth orbit satellites,with unique advantages,are prosperous types of navigation augmentation satellites for the GNSS satellites constellations.The broadcast ephemeris element needs to be designed as an important index of the augmented LEOs.The GPS ephemerides of 16/18 elements cannot be directly applied to the LEOs because of the poor fitting accuracies in along-track positional component.Besides,the ill-conditioned problem of the normal-matrix exists in fitting algorithm due to the small eccentricity of the LEO orbits.Based on the nonsingular orbital elements,5 sets of ephemerides with element numbers from 16 to 19 were designed respectively by adding or modifying orbital elements magnifying the along-track and radial positional components.The fitting experiments based on the LEO of 300 to 1500 km altitudes show that the fitting UREs of the proposed 16/17/18/18*/19-element ephemerides are better than 10/6/4/5/2.5 cm,respectively.According to the dynamical range of the fitting elements,the interfaces were designed for the 5 sets of ephemerides.The effects of data truncation on fitting UREs are at millimeter level.The total bits are 329/343/376/379/396,respectively.29/15 bits are saved for the 16/17-element ephemerides compared with the GPS16 ephemeris,while 64/61/41 bits can be saved for the 18/18*/19-element ephemerides compared with the GPS18 elements ephemeris.

Blast damage zone strength reduction method for deep cavern excavation and its application

The drill and blast(D&B)method is widely used to excavate underground spaces,but explosions generally cause damage to the rock.Still,no blast simulation method can provide computational accuracy and efficiency.In this paper,a blast equivalent simulation method called the blast damage zone strength reduction(BDZSR)method is proposed.This method first calculates the range of the blast-induced damage zone(BDZ)by formulae,then reduces the strength and deformation parameters of the rock within the BDZ ahead of excavation,and finally calculates the excavation damage zone(EDZ)for the D&B method by numerical simulation.This method combines stress wave attenuation,rock damage criteria and stress path variation to derive the BDZ depth calculation formulae.The formulae consider the initial geo-stress,and the reliability is verified by numerical simulations.The calculation of BDZ depth with these formulae allows the corresponding numerical simulation to avoid the time-consuming dynamic calculation process,thus greatly enhancing the calculation efficiency.The method was applied to the excavation in Jinping Class II hydropower station to verify its feasibility.The results show that the BDZSR method can be applied to blast simulation of underground caverns and provide a new way to study blast-induced damage.