Hydraulic fracture growth is significantly influenced by the minimum horizontal principal stress gradient and the fracturing fluid pressure gradient.However,these gradients are often neglected in scaled physical model...Hydraulic fracture growth is significantly influenced by the minimum horizontal principal stress gradient and the fracturing fluid pressure gradient.However,these gradients are often neglected in scaled physical modeling experiments due to difficulties in reproducing them.This study uses centrifugal hypergravity to simulate both gradients and investigate their effects on fracture propagation.Artificial mortar specimens(ϕ200 mm×400 mm)are fractured under 1g(normal gravity),50g,and 100g.Results show that compared to 1g,fractures under 50g and 100g exhibit increasingly uneven propagation,with higher g-values leading to greater asymmetry.To interpret this,a theoretical analysis based on fracture mechanics is conducted.When the fluid pressure gradient exceeds the stress gradient,a positive net gradient is generated,increasing net pressure at the lower fracture tip.This raises the stress intensity factor at the lower tip,promoting downward growth.As g increases,the disparity becomes more significant,resulting in greater fracture deviation.In conclusion,this study,for the first time,has verified and explained that the net gradient can change the propagation of hydraulic fractures,providing important guidance for wellbore placement under stress gradients.展开更多
We herein described an efficient and practical protocol for radical cyclization of aryl alkynoates to access 3-fluoroalkyl-substituted coumarins using readily available,easy-to-handle and low-cost fluoroalkyl carboxyl...We herein described an efficient and practical protocol for radical cyclization of aryl alkynoates to access 3-fluoroalkyl-substituted coumarins using readily available,easy-to-handle and low-cost fluoroalkyl carboxylic anhydride as fluoroalkyl source.This method is featured by its generally applicable to several kinds of fluoroalkyl carboxylic anhydrides including difluoromethy1,trifluoromethyl,pentafluoroethyl,heptafluoropropyl and chlorodifluoromethyl,as well as a good functional group tolerance with respect to a wide variety of aryl alkynoates.This reaction was triggered by addition of fluoroalkyl radical to the triple bond of alkynoates,followed by a cascade 5-exo cyclization/oxidization/1,2-ester migration/rearomatization process.展开更多
Therapeutic nanoparticles （NPs） based on the donor-acceptor-donor structured small organic molecule diketopyrrolopyrrole （SDPP） were prepared using a simple reprecipitation approach. These near-infrared radiation-...Therapeutic nanoparticles （NPs） based on the donor-acceptor-donor structured small organic molecule diketopyrrolopyrrole （SDPP） were prepared using a simple reprecipitation approach. These near-infrared radiation-absorbing NPs have high photothermal conversion efficiency and are able to selectively target cancer tissues through the enhanced permeability and retention effect. Benefiting from these advantages, SDPP NPs can serve as an excellent therapeutic agent for highly efficient and noninvasive photoacoustic imaging-guided photothermal therapy. Experiments using mouse tumor models showed that the SDPP NPs exhibited exceptional tumor ablation ability under laser irradiation （660 nm, 1.0 W.cm 2）, even at a low dose （0.16 mg.kg^-1）.展开更多
基金supports of Basic Science Center Program for Multiphase Evolution in Hyper-gravity of the National Natural Science Foundation of China(No.51988101)National Natural Science Foundation of China(Nos.52109138 and 52122403)Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001).
文摘Hydraulic fracture growth is significantly influenced by the minimum horizontal principal stress gradient and the fracturing fluid pressure gradient.However,these gradients are often neglected in scaled physical modeling experiments due to difficulties in reproducing them.This study uses centrifugal hypergravity to simulate both gradients and investigate their effects on fracture propagation.Artificial mortar specimens(ϕ200 mm×400 mm)are fractured under 1g(normal gravity),50g,and 100g.Results show that compared to 1g,fractures under 50g and 100g exhibit increasingly uneven propagation,with higher g-values leading to greater asymmetry.To interpret this,a theoretical analysis based on fracture mechanics is conducted.When the fluid pressure gradient exceeds the stress gradient,a positive net gradient is generated,increasing net pressure at the lower fracture tip.This raises the stress intensity factor at the lower tip,promoting downward growth.As g increases,the disparity becomes more significant,resulting in greater fracture deviation.In conclusion,this study,for the first time,has verified and explained that the net gradient can change the propagation of hydraulic fractures,providing important guidance for wellbore placement under stress gradients.
基金supported by the Natural Science Foundation of Fujian Province(No.2022J01500)the National Natural Science Foundation of China(No.22071241)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZZ105).
文摘We herein described an efficient and practical protocol for radical cyclization of aryl alkynoates to access 3-fluoroalkyl-substituted coumarins using readily available,easy-to-handle and low-cost fluoroalkyl carboxylic anhydride as fluoroalkyl source.This method is featured by its generally applicable to several kinds of fluoroalkyl carboxylic anhydrides including difluoromethy1,trifluoromethyl,pentafluoroethyl,heptafluoropropyl and chlorodifluoromethyl,as well as a good functional group tolerance with respect to a wide variety of aryl alkynoates.This reaction was triggered by addition of fluoroalkyl radical to the triple bond of alkynoates,followed by a cascade 5-exo cyclization/oxidization/1,2-ester migration/rearomatization process.
基金The work was supported by the National Basic Research Program of China （No. 2014CB660808）, the National Natural Science Foundation of China （Nos. 61525402 and 21275076）, Key University Science Research Project of Jiangsu Province （No. 15KJA430006）, Program for New Century Excellent Talents in University （No. NCET-13-0853）, QingLan Project, Jiangsu Province Science Foundation for Six Great Talent Peak （No. XCL-018）.
文摘Therapeutic nanoparticles （NPs） based on the donor-acceptor-donor structured small organic molecule diketopyrrolopyrrole （SDPP） were prepared using a simple reprecipitation approach. These near-infrared radiation-absorbing NPs have high photothermal conversion efficiency and are able to selectively target cancer tissues through the enhanced permeability and retention effect. Benefiting from these advantages, SDPP NPs can serve as an excellent therapeutic agent for highly efficient and noninvasive photoacoustic imaging-guided photothermal therapy. Experiments using mouse tumor models showed that the SDPP NPs exhibited exceptional tumor ablation ability under laser irradiation （660 nm, 1.0 W.cm 2）, even at a low dose （0.16 mg.kg^-1）.
