A review of rock macro-indentation:Theories,experiments,simulations,and applications

Rock macro-indentation plays a fundamental role in mechanical rock breaking for various rock engineering application,such as drilling,tunneling,cutting,and sawing.Over the past decades,extensive research has been conducted to understand the indentation mechanisms and responses through various approaches.This review aims to provide an overview of the current status and recent advancements in theories,experiments,numerical simulations,and applications of macro-indentation in rock engineering.It starts with elaborating on the mechanisms of macro-indentation,followed by a discussion of the merits and limitations of commonly used models.Influence factors and their effects on indentation test results are then summarized.Various numerical simulation methods for rock macro-indentation are highlighted,along with their advantages and disadvantages.Subsequently,the applications of indentation tests and indentation indices in characterizing rock properties are explored.It reveals that compression-tension,compression-shear,and composite models are widely employed in rock macroindentation.While the compression-tension model is straightforward to use,it may overlook the anisotropic properties of rocks.On the other hand,the composite model provides a more comprehensive description of rock indentation but requires complex calculations.Additionally,factors,such as indentation rate,indenter geometry,rock type,specimen size,and confining pressure,can significantly influence the indentation results.Simulation methods for macro-indentation encompass continuous medium,discontinuous medium,and continuous-discontinuous medium methods,with selection based on their differences in principle.Furthermore,rock macro-indentation can be practically applied to mining engineering,tunneling engineering,and petroleum drilling engineering.Indentation indices serve as valuable tools for characterizing rock strength,brittleness,and drillability.This review sheds light on the development of rock macro-indentation and its extensive application in engineering practice.Specialists in the field can gain a comprehensive understanding of the indentation process and its potential in various rock engineering endeavors.

Effects of Gibberellin and Ultrasonic on Seed Germination Characteristics of Different Strawberry Cultivars

Four kinds of strawberry(Benihoppe, Akihime, Tuscany and Qianmei) seeds were taken as the materials, to study the effects of gibberellin in different concentrations and ultrasonic treatment on seed germination. The results showed that thousand kernel weights of seeds from different strawberry varieties had significant difference, and the sequence was Benihoppe=Akihime>Qianmei>Tuscany. Gibberellin treatment could improve germination rate of strawberry seed, and the optimal gibberellin concentrations for Benihoppe, Tuscany, Qianmei and Akihime were 5, 5, 5 and 10 mol/L. Gibberellin treatment could improve germination potential of Tuscany and Qianmei, and germination potential rose with gibberellin concentration increased within certain range, while ultrasonic treatment obviously inhibited germination of strawberry seed.

Prognostic value of negative lymph node count in patients with jejunoileal neuroendocrine tumors

A negative lymph node(NLN)count has been shown to have a significant impact on the prognosis of many types of cancer.However,its prognostic value for jejunoileal neuroendocrine tumors(NETs)remains unclear.In this study,we investigated the prognostic value of NLN count in patients with resected jejunoileal NETs diagnosed between 1988 and 2014.The data were retrieved from the Surveillance,Epidemiology and End Results database.The X-tile program was used to determine the cutoff value of the NLN count.Univariate and multivariate Cox proportional hazards models were used to assess the prognostic value of NLN count on survival.Harrell concordance index was used to compare the prognostic validity of NLN count with 2 current prognostic systems.The optimal cutoff point of the NLN count was 8.Kaplan-Meier analysis revealed a progressively worse overall survival(OS)with an NLN count≤8 compared with an NLN count>8(P<0.001).Univariate analysis showed that the NLN count,age,tumor site,tumor size and T classification were significant prognostic factors for the OS of jejunoileal NETs,while the number of positive lymph nodes had no significant impact on OS(P=0.513).Multivariate analysis indicated that the NLN count was an independent prognostic factor for OS of jejunoileal NETs.A higher NLN count was associated with better OS(hazards ratio:0.641;95%confidence interval:0.519-0.793;P<0.001).Compared with 2 other prognostic systems,the NLN counts in this study had similar prognostic value in patients with jejunoileal NETs.Our findings suggest that the NLN count is an important independent prognostic factor for patients with jejunoileal NETs,and that it is a good adjunct for disease staging.