Earth Pressure of the Trapdoor Problem Using Three-Dimensional Discrete Element Method

Load transformation from the yielding part of the soil to the adjacent part is known as the soil arching effect,which plays an important role in the design of various geotechnical infrastructures.Terzaghi’s trapdoor test was an importantmilestone in the development of theories on soil arching.The research on earth pressure of the trapdoor problem is presented in this paper using the three-dimensional(3D)discrete element method(DEM).Five 3D trapdoor models with different heights are established by 3DDEMsoftware PFC 3D.The variation of earth pressure on the trapdoor with the downward movement of the trapdoor,the distribution of vertical earth pressure along the horizontal direction,the distribution of vertical earth pressure along the vertical direction,the distribution of lateral earth pressure coefficient along the depth direction,the magnitude and direction of contact force chain are studied,respectively.Related research results show that the earth pressure on the trapdoor decreases rapidly after the downward movement of the trapdoor,and then reaches the minimum earth pressure.After that,the earth’s pressure will rise slightly,and whether this phenomenon occurs depends on the depth ratio.For the bottom soil,due to the stress transfer caused by the soil arching effect,the ratio of earth pressure in the loose area decreases,while the ratio of earth pressure in the stable area increases.With the trapdoor moving down,the vertical earth pressure along the depth in the stable zone is basically consistent with the initial state,which shows an approximate linear distribution.After the trapdoor moves down,the distribution of earth pressure along with the depth in the loose area changes,which is far less than the theoretical value of vertical earth pressure of its self-weight.Because of the compression of the soil on both sides,the lateral earth pressure coefficient of most areas on the central axis of the loose zone is close to the passive earth pressure coefficient Kp.The existence of a‘soil arch’can be observed intuitively from the distribution diagram of the contact force chain in the loose zone.

MYB41,MYB107,and MYC2 promote ABA-mediated primary fatty alcohol accumulation via activation of AchnFAR in wound suberization in kiwifruit

Wound damage triggers the accumulation of abscisic acid(ABA),which induces the expression of a large number of genes involved in wound suberization in plants.Fatty acyl-CoA reductase(FAR)catalyzes the generation of primary fatty alcohols by the reduction of fatty acids in suberin biosynthesis.However,the regulatory effects of transcription factors(TFs)on AchnFAR in response to ABA are unexplored.In this study,kiwifruit AchnFAR displayed a biological function analogous to that of FAR in transiently overexpressed tobacco(Nicotiana benthamiana)leaves.The positive role of TFs,including AchnMYB41,AchnMYB107,and AchnMYC2,in the regulation of AchnFAR was identified.The three TFs could individually bind to the AchnFAR promoter to activate gene transcription in yeast one-hybrid and dualluciferase assays.Transient overexpression of TFs in tobacco leaves resulted in the upregulation of aliphatic synthesis genes(including FAR)and the increase in aliphatics,including primary alcohols,α,ω-diacids,ω-hydroxyacids,and fatty acids.Moreover,exogenous ABA treatment elevated TF-mediated AchnFAR expression and the accumulation of primary alcohols.Conversely,fluridone,an inhibitor of ABA biosynthesis,suppressed the expression of AchnFAR and TF genes and reduced the formation of primary alcohols.The results indicate that AchnMYB41,AchnMYB107,and AchnMYC2 activate AchnFAR transcription to promote ABA-mediated primary alcohol formation in wound suberization in kiwifruit.

Naringin,neohesperidin and their corresponding dihydrochalcones as bioactive substances:a symphony of bitter–sweet

Bitter is generally undesirable,although it is an important part of flavor.Bitter substances exhibit diverse health-promoting activities,which is in line with the famous Chinese saying‘a good medicine tastes bitter’.Naringin(NAG)and neohesperidin(NHP),two important flavanones that give bitterness to citrus fruits,show various pharmacological activities.Interestingly,their hydrogenation products,i.e.naringin dihydrochalcone(NDC)and neohesperidin dihydrochalcone(NHDC),undergo a dramatic taste shift from bitter to intensely sweet,which can be 300 and 1000 times sweeter than sucrose,respectively.Such sweeteners not only provide a sweet taste without the burden of increased calorie intake and glycemia,but also may exert multiple bioactivities.This review summarizes common dietary bitter and sweet compounds with sensory scores.Taste conversions induced by structural changes from bitter NAG and NHP to sweet NDC and NHDC are particularly discussed.In addition,the taste-sensing mechanisms,pharmacological characteristics,dietary distribution,synthesis,and food industry applications of these bitter–sweet interchangeable compounds are outlined.In conclusion,the bitter NAG and NHP are promising therapeutic candidates for management of diverse etiologically complex diseases while their corresponding dihydrochalcones NDC and NHDC are promising sweeteners,which might be a blessing for those who need to control sugar intake.