To simplify the complicated design process of deployable/retractable structures, a new design process is developed. The process is divided into three phases： the concept design phase, the model phase and the optimiza...To simplify the complicated design process of deployable/retractable structures, a new design process is developed. The process is divided into three phases： the concept design phase, the model phase and the optimization phase. In each phase, different parameter targets have to be fulfilled. According to three phases, a deployable/retractable mast composed of four right triangle prism modules in the longitudinal direction is designed. It can be deployed and folded simultaneously by the linear movements of sleeve-joints. The deployable and retractable movement of the mast is analyzed and key joint forms are designed. Then bar diameters and joint forms are modified based on mast structural mechanics characteristics in the optimization phase. Finally a 1：1 scaled model mast is built to verify the design and the optimization. Analytical results show that the model mast has the advantages of simple locking mechanism, fewer types of joints and bars, so it can be easily manufactured.展开更多
Deployable/retractable damped cantilever beams are a class of time-varying parametric structures which have attracted considerable research interest due to their many potential applications in the intelligent robot fi...Deployable/retractable damped cantilever beams are a class of time-varying parametric structures which have attracted considerable research interest due to their many potential applications in the intelligent robot field and aerospace.In the present work,the dynamic characteristics of a deployable/retractable damped cantilever beam are investigated experimentally and theoretically.The time-varying damping,as a function of the beam length,is obtained by both the enveloped fitting method and the period decrement method.Furthermore,the governing equation of the deployable/retractable damped cantilever beam is derived by introducing the time-varying damping parameter,and the corresponding closed-form solution and vibration principles are investigated based on the averaged method.The theoretical predictions for transient dynamic responses are in good agreement with the experimental results.The dynamic mechanism analysis on time-varying damping offers flexible technology in mechanical and aerospace fields.展开更多
To solve the problem that the overlapping parts of a retractable pier column are prone to damage,this paper proposed the reinforcing measure of setting a stiffener ring at the bottom of the steel pipe.To study how the...To solve the problem that the overlapping parts of a retractable pier column are prone to damage,this paper proposed the reinforcing measure of setting a stiffener ring at the bottom of the steel pipe.To study how the stiffener-ring parameters influence the mechanical properties of the pier column.12 scale model specimens(including nine specimens with stiffener-ring widths of 40,50,and 60 mm and three unstiffened comparison specimens)were tested under axial compression.Based on the test results,the specimen load-displacement,load-deflection,and load-strain curves were analyzed,and a finite-element model of a pier column under axial compression was established to determine the optimal stiffener size.The results show that setting a stiffener ring enhances the cooperative working ability between the steel pipe and the internal filling material and restrains the lateral deformation of the pier column,thereby improving the ultimate bearing capacity and overall stability of the pier column.The ultimate bearing capacity of the pier column is related to the width and thickness of the stiffener ring.The optimal size of the stiffener ring of the model pier column is 70 mm in width and 4 mm in thickness.The present research results provide a reference for designing compressible pier columns and column stiffening in mines and have important practical significance.展开更多
The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is ...The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is driven by the expanding or contracting walls with different permeability. The velocities of the asymmetric flow at the upper and lower walls are different in not only the magnitude but also the direction. The asymptotic solutions are well constructed with the method of boundary layer correction in two cases with large Reynolds numbers, i.e., both walls of the channel are with suction, and one of the walls is with injection while the other one is with suction. For small Reynolds number cases, the double perturbation method is used to construct the asymptotic solution. All the asymptotic results are finally verified by numerical results.展开更多
In this paper we introduce a class of right S-acts called retractable S-acts which are right S-acts with homomorphisms into their all subacts. We also give some classifications of monoids by comparing such acts with f...In this paper we introduce a class of right S-acts called retractable S-acts which are right S-acts with homomorphisms into their all subacts. We also give some classifications of monoids by comparing such acts with flatness properties.展开更多
Casing-while-drilling(CWD)with down the hole(DTH)hammer drilling technology has been widely used in unconsolidated formations,due to its advantages in protecting the borehole wall,excellent rock cuttings capacity,and ...Casing-while-drilling(CWD)with down the hole(DTH)hammer drilling technology has been widely used in unconsolidated formations,due to its advantages in protecting the borehole wall,excellent rock cuttings capacity,and fast penetration rate in hard rock.As an important component of the CWD system,the structure of the retractable drill bit needs not only to ensure to form stronger reverse circulation,but also to be expandable or retractable as needed,otherwise the drill bit cannot be lift and put down smoothly in the casing,and may lead to drilling accidents.This paper developed a new type of reverse circulation DTH hammer drill bit used for CWD drilling technology.The retractable performance of this type of drill bit is studied using ADAMS software.The results show that it is smoothly expandable and retractable as designed under the conditions of the weight of the bit(WOB)of 0.5–2.0 t and the rotation speed of 30–60 r/min.To investigate the reverse circulation effect of the drill bit,Fluent software was used to simulate the flow characteristic inside it.The simulation results indicated that it can form strong reverse circulation,and the entrainment ratio h can reach 9.5%.展开更多
A novel structure of a spherical robot with retractable arms was presented in order to fulfill the requirements of omni-direction movement and operation mission. Under the assumption of rolling without slipping, nonho...A novel structure of a spherical robot with retractable arms was presented in order to fulfill the requirements of omni-direction movement and operation mission. Under the assumption of rolling without slipping, nonholonomic constraints were revealed and a dynamics model of the proposed robot was constructed by use of Kane＇s method. Numerical simulations about rectilinear motion and sigmoid curve motion of the system were carried out in Matlab, and as a comparison, the same trajectories were also implemented by a virtual prototype in ADAMS, which validate the derived dynamical model accordingly. With the derived dynamical model, torques/forces of joints were analyzed. The results indicate the disturbance forces or torques on each joint are not zero under the state of sphere moving, and with rational planning for the trajectory of the robot, there will be a great decrease of the disturbance forces or torques acting on the spherical caps and arms.展开更多
Landing gears are one of the key components for large or middle unmanned aerial vehicles,and their working performances directly affect flying security and aircraft taking-off and landing performance.Thus,it is meanin...Landing gears are one of the key components for large or middle unmanned aerial vehicles,and their working performances directly affect flying security and aircraft taking-off and landing performance.Thus,it is meaningful to study the retraction system.Based on CATIA and ADAMS software platforms,a virtual model of landing gear retraction system is built for performance test,and then dynamic simulation is carried out.Afterwards,a test system for landing gear retraction is established,and the test data are compared with the results acquired from dynamics simulation.The main factors which affect the dynamic performance of retractable landing gear are analyzed emphatically.The simulation results show that aerodynamic load has an impact on retraction time,the mass force affects extension process,and the oil hole size of hydraulic actuator has an effect on both retraction time and extension time.展开更多
The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong ...The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong Tennis Center.By elasto-plastic finite element analysis and shaking table test,the following were investigated:the effects of roof configurations in opening and closing,the effect of pre-stress on the structural seismic response,and the failure mechanism of the spatial stand frame systems featured with circularly arranged columns and inverse-cone type stands.It was found thatthe roof status has great effect on the natural period,vibration modes,and seismic response of the whole structure,the stand response to horizontal seismic excitation is stronger in roof opening configuration than in closing state,and the response mode is dominantly translational rather than rotational,though the stand is characterized by its fundamentally torsional vibration mode.The study indicated that the pre-stressed inversecone stands can keep the system from global side-sway collapse under gravity loads,even in the case that most columns loose moment capacity.展开更多
AIM:To investigate the effect of pentagonal conjunctival autograft on reducing graft retraction following pterygium surgery.METHODS:This retrospective comparative study included patients who underwent primary pterygiu...AIM:To investigate the effect of pentagonal conjunctival autograft on reducing graft retraction following pterygium surgery.METHODS:This retrospective comparative study included patients who underwent primary pterygium excision with either pentagonal(created by shaping the junction with the recipient conjunctiva into a wedge)or quadrangular conjunctival autograft transplantation.All patients completed a 6mo postoperative follow-up.The primary outcome measure was the incidence of graft retraction;secondary outcomes included graft displacement requiring re-suturing and pterygium recurrence rate.RESULTS:The study enrolled 58 participants,comprising 26(15 males,11 females)in the pentagonal graft group(mean age:54.9±13.1y),and 32(17 males,15 females)in the quadrangular graft group(mean age:57.6±10.4y).Graft retraction occurred in only 1 eye(3.8%)in the pentagonal autograft group,compared to 9 eyes(28.1%)in the quadrangular autograft group.No cases of graft displacement requiring re-suturing were reported in the pentagonal autograft group.Although graft displacement and recurrence requiring re-suturing were observed less frequently in surgeries with a pentagonal graft,the difference was not statistically significant(P>0.05).CONCLUSION:Designing the conjunctival autograft in a pentagonal shape—mimicking geodesic dome architecture and conforming to the eye’s spherical structure—enhances compatibility with the recipient conjunctiva and improves resistance to physical traction forces.This design effectively reduces the incidence of graft retraction and other related complications,providing a more favorable surgical option for pterygium treatment.展开更多
Taking domains in the one hand and actions of a semigroup （automaton） on the other, as two crucial notions in mathematics as well as in computer science, we consider the notion of compact directed complete poset （a...Taking domains in the one hand and actions of a semigroup （automaton） on the other, as two crucial notions in mathematics as well as in computer science, we consider the notion of compact directed complete poset （acts）, and investigate the interesting notion of absolute retractness for such ordered structures. As monomorphisms and embeddings for domain acts are different notions, we study absolute retractness with respect to both the class of monomorphisms and that of embed- dings for compact directed complete poset （acts）. We characterize the absolutely retract compact dcpos as complete compact chains. Also, we give some examples of compact di- rected complete poset acts which are （g-）absolutely retract （with respect to embeddings） and show that completeness is not a sufficient condition for （g-）absolute retractness.展开更多
BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,sli...BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,slight postoperative pain,faster recovery.Despite the advantages mentioned above,the currently available specialized single-port laparoscopic instruments are hindered by high costs and limited applications,challenging their widespread use in medical facilities.AIM To design a two-point lifting/retracting(TPLR)technique for transumbilical single-port LC(TUSPLC)based on the anatomical features of the Calot's triangle(or cystohepatic triangle)and investigate its surgical feasibility.METHODS The clinical data of 103 patients who underwent TUSPLC utilizing the TPLR technique in the Department of Hepatobiliary Surgery at our hospital between June 2023 and June 2024 were retrospectively analyzed.The patient cohort included 82 cases of cholelithiasis,11 cases of gallbladder polyps,6 cases of concurrent gallstones and polyps,and 4 cases of gallbladder adenomyomatosis.RESULTS All the surgical procedures were conducted using standard laparoscopic instruments.Surgery was successful in 98(95.14%)patients using the TPLR method,which effectively exposed the Calot's triangle during surgery.The operative time ranged from 35 to 70 minutes,with an average of 42.4±26.8 minutes.In 3 cases,an additional operative port was required below the xiphoid process,and 2 cases were converted to conventional three-port LC.No complications such as abdominal pain,fever,bile leakage,hemorrhage,or incisional infection were noted postoperatively.No discernible surgical scars were observed at the 2-week postoperative reexamination.Additionally,a 3-month follow-up period revealed no complications.CONCLUSION The TPLR technique,developed based on the anatomical features of the Calot's triangle,facilitates exposure of the Calot's triangle during surgery.It is a simple,safe,feasible,and cost-effective method,and a promising approach for single-port LC.展开更多
The retraction note addresses allegations concerning the published article titled“Efficacy and safety analysis of transarterial chemoembolization and transarterial radioembolization in advanced hepatocellular carcino...The retraction note addresses allegations concerning the published article titled“Efficacy and safety analysis of transarterial chemoembolization and transarterial radioembolization in advanced hepatocellular carcinoma descending hepatec-tomy”.World J Gastrointest Surg 2023;15:687-697.To preserve academic integrity and avoid misleading the readers,the authors agreed to retract the article,due to significant concerns regarding the reliability of the transarterial radioembolization data obtained by exploratory,non-standardized interventional procedures and ethical compliance in this study,which severely damaged the conclusion in this study.The authors sincerely apologize to the readers,reviewers and editors for these errors and for any inconvenience caused by this retraction.展开更多
Purpose:This study examines the impact of research policy changes on scientific retractions of publications authored by Romanian authors,focusing on national trends and the interplay between policy reforms and publish...Purpose:This study examines the impact of research policy changes on scientific retractions of publications authored by Romanian authors,focusing on national trends and the interplay between policy reforms and publishing practices.Design/methodology/approach:Using data from the Retraction Watch Database and Web of Science(WoS),188 unique retractions involving Romanian authors(2000-2022)were analyzed.The study compared retraction patterns before and after the 2016 reforms,which prioritized the publication of articles in WoS-indexed journals over non-WoS outputs.Findings:The analysis identified two key trends:(1)before the 2016 reforms,retractions predominantly involved non-WoS journals(99 non-WoS retractions to 38 WoS retractions),a trend that reversed post-reform(16 non-WoS to 35 WoS),and(2)while the total number of WoS-indexed retractions increased after the reforms,the retraction rates for WoS articles remained stable.Post-reform reliance on MDPI journals,which have low retraction rates,partially explains this stability.Excluding MDPI publications,retraction rates for articles and reviews increase by 14.91%,aligning with patterns seen elsewhere.Research limitations:The study focuses on retractions involving Romanian authors,limiting its generalizability.Furthermore,reliance on database records may not fully capture all retractions.Practical implications:These findings underscore the need for research policy reforms to consider a broader range of effects,and the need for nuanced interpretations of retraction data,which are influenced by a complex range of factors,including specific publisher practices.Originality/value:This research is the first to investigate the complex relationship between research policy reforms,publisher behavior,and retraction trends.展开更多
Following the publication,concerns have been raised about a number of figures in this article.The western blots in this article were presented with atypical,unusually shaped and possibly anomalous protein bands in man...Following the publication,concerns have been raised about a number of figures in this article.The western blots in this article were presented with atypical,unusually shaped and possibly anomalous protein bands in many cases.展开更多
The published article titled“MicroRNA-33b Inhibits the Proliferation andMigration of Osteosarcoma Cells via TargetingHypoxia-Inducible Factor-1α”has been retracted from Oncology Research,Vol.25,No.3,2017,pp.397–405.
Following the publication,concerns have been raised about a number of figures in this article.An unexpected area of similarity was identified in terms of the cellular data,where the results from differently performed ...Following the publication,concerns have been raised about a number of figures in this article.An unexpected area of similarity was identified in terms of the cellular data,where the results from differently performed experiments were intended to have been shown,although the areas immediately surrounding this area featured comparatively different distributions of cells.In addition,the western blots in this article were presented with atypical,unusually shaped and possibly anomalous protein bands in many cases.展开更多
The published article titled“UCA1 Regulates the Growth and Metastasis of Pancreatic Cancer by Sponging miR-135a”has been retracted from Oncology Research,Vol.25,No.9,2017,pp.1529–1541.DOI:10.3727/096504017X14888987...The published article titled“UCA1 Regulates the Growth and Metastasis of Pancreatic Cancer by Sponging miR-135a”has been retracted from Oncology Research,Vol.25,No.9,2017,pp.1529–1541.DOI:10.3727/096504017X14888987683152 URL:https://www.techscience.com/or/v25n9/56938 Following the publication,concerns have been raised about a number of figures in this article.An unexpected area of similarity was identified in terms of the cellular data,where the results from differently performed experiments were intended to have been shown,although the areas immediately surrounding this area featured comparatively different distributions of cells.展开更多
Traditionally,liver retraction for laparoscopic gastrectomy is done via manual methods,such as the placement of retractors through the accessory ports and using a Nathanson retractor.However,these techniques often pos...Traditionally,liver retraction for laparoscopic gastrectomy is done via manual methods,such as the placement of retractors through the accessory ports and using a Nathanson retractor.However,these techniques often posed issues including extra abdominal incisions,risk of liver injury or ischaemia,and the potential for compromised visualization.Over the years,the development of innovative liver retraction techniques has significantly improved the safety and efficacy of laparoscopic gastrectomy and similar other hiatal procedures.This editorial will comment on the article by Lin et al,and compare this to the other liver retractor techniques available for surgeons and highlight the pros and cons of each technique of liver retraction.展开更多
文摘To simplify the complicated design process of deployable/retractable structures, a new design process is developed. The process is divided into three phases： the concept design phase, the model phase and the optimization phase. In each phase, different parameter targets have to be fulfilled. According to three phases, a deployable/retractable mast composed of four right triangle prism modules in the longitudinal direction is designed. It can be deployed and folded simultaneously by the linear movements of sleeve-joints. The deployable and retractable movement of the mast is analyzed and key joint forms are designed. Then bar diameters and joint forms are modified based on mast structural mechanics characteristics in the optimization phase. Finally a 1：1 scaled model mast is built to verify the design and the optimization. Analytical results show that the model mast has the advantages of simple locking mechanism, fewer types of joints and bars, so it can be easily manufactured.
基金Project supported by the National Natural Science Foundation of China(Nos.11672007 and 11832002)the Graduate Technological Innovation Project of Beijing Institute of Technology(No.2017CX10037)。
文摘Deployable/retractable damped cantilever beams are a class of time-varying parametric structures which have attracted considerable research interest due to their many potential applications in the intelligent robot field and aerospace.In the present work,the dynamic characteristics of a deployable/retractable damped cantilever beam are investigated experimentally and theoretically.The time-varying damping,as a function of the beam length,is obtained by both the enveloped fitting method and the period decrement method.Furthermore,the governing equation of the deployable/retractable damped cantilever beam is derived by introducing the time-varying damping parameter,and the corresponding closed-form solution and vibration principles are investigated based on the averaged method.The theoretical predictions for transient dynamic responses are in good agreement with the experimental results.The dynamic mechanism analysis on time-varying damping offers flexible technology in mechanical and aerospace fields.
文摘To solve the problem that the overlapping parts of a retractable pier column are prone to damage,this paper proposed the reinforcing measure of setting a stiffener ring at the bottom of the steel pipe.To study how the stiffener-ring parameters influence the mechanical properties of the pier column.12 scale model specimens(including nine specimens with stiffener-ring widths of 40,50,and 60 mm and three unstiffened comparison specimens)were tested under axial compression.Based on the test results,the specimen load-displacement,load-deflection,and load-strain curves were analyzed,and a finite-element model of a pier column under axial compression was established to determine the optimal stiffener size.The results show that setting a stiffener ring enhances the cooperative working ability between the steel pipe and the internal filling material and restrains the lateral deformation of the pier column,thereby improving the ultimate bearing capacity and overall stability of the pier column.The ultimate bearing capacity of the pier column is related to the width and thickness of the stiffener ring.The optimal size of the stiffener ring of the model pier column is 70 mm in width and 4 mm in thickness.The present research results provide a reference for designing compressible pier columns and column stiffening in mines and have important practical significance.
基金Project supported by the National Natural Science Foundation of China(Nos.91430106 and11771040)the Fundamental Research Funds for the Central Universities of China(No.06500073)
文摘The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is driven by the expanding or contracting walls with different permeability. The velocities of the asymmetric flow at the upper and lower walls are different in not only the magnitude but also the direction. The asymptotic solutions are well constructed with the method of boundary layer correction in two cases with large Reynolds numbers, i.e., both walls of the channel are with suction, and one of the walls is with injection while the other one is with suction. For small Reynolds number cases, the double perturbation method is used to construct the asymptotic solution. All the asymptotic results are finally verified by numerical results.
文摘In this paper we introduce a class of right S-acts called retractable S-acts which are right S-acts with homomorphisms into their all subacts. We also give some classifications of monoids by comparing such acts with flatness properties.
基金the National Key Research and Development Program of China(No.2018YFC1505303).
文摘Casing-while-drilling(CWD)with down the hole(DTH)hammer drilling technology has been widely used in unconsolidated formations,due to its advantages in protecting the borehole wall,excellent rock cuttings capacity,and fast penetration rate in hard rock.As an important component of the CWD system,the structure of the retractable drill bit needs not only to ensure to form stronger reverse circulation,but also to be expandable or retractable as needed,otherwise the drill bit cannot be lift and put down smoothly in the casing,and may lead to drilling accidents.This paper developed a new type of reverse circulation DTH hammer drill bit used for CWD drilling technology.The retractable performance of this type of drill bit is studied using ADAMS software.The results show that it is smoothly expandable and retractable as designed under the conditions of the weight of the bit(WOB)of 0.5–2.0 t and the rotation speed of 30–60 r/min.To investigate the reverse circulation effect of the drill bit,Fluent software was used to simulate the flow characteristic inside it.The simulation results indicated that it can form strong reverse circulation,and the entrainment ratio h can reach 9.5%.
文摘A novel structure of a spherical robot with retractable arms was presented in order to fulfill the requirements of omni-direction movement and operation mission. Under the assumption of rolling without slipping, nonholonomic constraints were revealed and a dynamics model of the proposed robot was constructed by use of Kane＇s method. Numerical simulations about rectilinear motion and sigmoid curve motion of the system were carried out in Matlab, and as a comparison, the same trajectories were also implemented by a virtual prototype in ADAMS, which validate the derived dynamical model accordingly. With the derived dynamical model, torques/forces of joints were analyzed. The results indicate the disturbance forces or torques on each joint are not zero under the state of sphere moving, and with rational planning for the trajectory of the robot, there will be a great decrease of the disturbance forces or torques acting on the spherical caps and arms.
文摘Landing gears are one of the key components for large or middle unmanned aerial vehicles,and their working performances directly affect flying security and aircraft taking-off and landing performance.Thus,it is meaningful to study the retraction system.Based on CATIA and ADAMS software platforms,a virtual model of landing gear retraction system is built for performance test,and then dynamic simulation is carried out.Afterwards,a test system for landing gear retraction is established,and the test data are compared with the results acquired from dynamics simulation.The main factors which affect the dynamic performance of retractable landing gear are analyzed emphatically.The simulation results show that aerodynamic load has an impact on retraction time,the mass force affects extension process,and the oil hole size of hydraulic actuator has an effect on both retraction time and extension time.
文摘The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong Tennis Center.By elasto-plastic finite element analysis and shaking table test,the following were investigated:the effects of roof configurations in opening and closing,the effect of pre-stress on the structural seismic response,and the failure mechanism of the spatial stand frame systems featured with circularly arranged columns and inverse-cone type stands.It was found thatthe roof status has great effect on the natural period,vibration modes,and seismic response of the whole structure,the stand response to horizontal seismic excitation is stronger in roof opening configuration than in closing state,and the response mode is dominantly translational rather than rotational,though the stand is characterized by its fundamentally torsional vibration mode.The study indicated that the pre-stressed inversecone stands can keep the system from global side-sway collapse under gravity loads,even in the case that most columns loose moment capacity.
文摘AIM:To investigate the effect of pentagonal conjunctival autograft on reducing graft retraction following pterygium surgery.METHODS:This retrospective comparative study included patients who underwent primary pterygium excision with either pentagonal(created by shaping the junction with the recipient conjunctiva into a wedge)or quadrangular conjunctival autograft transplantation.All patients completed a 6mo postoperative follow-up.The primary outcome measure was the incidence of graft retraction;secondary outcomes included graft displacement requiring re-suturing and pterygium recurrence rate.RESULTS:The study enrolled 58 participants,comprising 26(15 males,11 females)in the pentagonal graft group(mean age:54.9±13.1y),and 32(17 males,15 females)in the quadrangular graft group(mean age:57.6±10.4y).Graft retraction occurred in only 1 eye(3.8%)in the pentagonal autograft group,compared to 9 eyes(28.1%)in the quadrangular autograft group.No cases of graft displacement requiring re-suturing were reported in the pentagonal autograft group.Although graft displacement and recurrence requiring re-suturing were observed less frequently in surgeries with a pentagonal graft,the difference was not statistically significant(P>0.05).CONCLUSION:Designing the conjunctival autograft in a pentagonal shape—mimicking geodesic dome architecture and conforming to the eye’s spherical structure—enhances compatibility with the recipient conjunctiva and improves resistance to physical traction forces.This design effectively reduces the incidence of graft retraction and other related complications,providing a more favorable surgical option for pterygium treatment.
文摘Taking domains in the one hand and actions of a semigroup （automaton） on the other, as two crucial notions in mathematics as well as in computer science, we consider the notion of compact directed complete poset （acts）, and investigate the interesting notion of absolute retractness for such ordered structures. As monomorphisms and embeddings for domain acts are different notions, we study absolute retractness with respect to both the class of monomorphisms and that of embed- dings for compact directed complete poset （acts）. We characterize the absolutely retract compact dcpos as complete compact chains. Also, we give some examples of compact di- rected complete poset acts which are （g-）absolutely retract （with respect to embeddings） and show that completeness is not a sufficient condition for （g-）absolute retractness.
文摘BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,slight postoperative pain,faster recovery.Despite the advantages mentioned above,the currently available specialized single-port laparoscopic instruments are hindered by high costs and limited applications,challenging their widespread use in medical facilities.AIM To design a two-point lifting/retracting(TPLR)technique for transumbilical single-port LC(TUSPLC)based on the anatomical features of the Calot's triangle(or cystohepatic triangle)and investigate its surgical feasibility.METHODS The clinical data of 103 patients who underwent TUSPLC utilizing the TPLR technique in the Department of Hepatobiliary Surgery at our hospital between June 2023 and June 2024 were retrospectively analyzed.The patient cohort included 82 cases of cholelithiasis,11 cases of gallbladder polyps,6 cases of concurrent gallstones and polyps,and 4 cases of gallbladder adenomyomatosis.RESULTS All the surgical procedures were conducted using standard laparoscopic instruments.Surgery was successful in 98(95.14%)patients using the TPLR method,which effectively exposed the Calot's triangle during surgery.The operative time ranged from 35 to 70 minutes,with an average of 42.4±26.8 minutes.In 3 cases,an additional operative port was required below the xiphoid process,and 2 cases were converted to conventional three-port LC.No complications such as abdominal pain,fever,bile leakage,hemorrhage,or incisional infection were noted postoperatively.No discernible surgical scars were observed at the 2-week postoperative reexamination.Additionally,a 3-month follow-up period revealed no complications.CONCLUSION The TPLR technique,developed based on the anatomical features of the Calot's triangle,facilitates exposure of the Calot's triangle during surgery.It is a simple,safe,feasible,and cost-effective method,and a promising approach for single-port LC.
文摘The retraction note addresses allegations concerning the published article titled“Efficacy and safety analysis of transarterial chemoembolization and transarterial radioembolization in advanced hepatocellular carcinoma descending hepatec-tomy”.World J Gastrointest Surg 2023;15:687-697.To preserve academic integrity and avoid misleading the readers,the authors agreed to retract the article,due to significant concerns regarding the reliability of the transarterial radioembolization data obtained by exploratory,non-standardized interventional procedures and ethical compliance in this study,which severely damaged the conclusion in this study.The authors sincerely apologize to the readers,reviewers and editors for these errors and for any inconvenience caused by this retraction.
文摘Purpose:This study examines the impact of research policy changes on scientific retractions of publications authored by Romanian authors,focusing on national trends and the interplay between policy reforms and publishing practices.Design/methodology/approach:Using data from the Retraction Watch Database and Web of Science(WoS),188 unique retractions involving Romanian authors(2000-2022)were analyzed.The study compared retraction patterns before and after the 2016 reforms,which prioritized the publication of articles in WoS-indexed journals over non-WoS outputs.Findings:The analysis identified two key trends:(1)before the 2016 reforms,retractions predominantly involved non-WoS journals(99 non-WoS retractions to 38 WoS retractions),a trend that reversed post-reform(16 non-WoS to 35 WoS),and(2)while the total number of WoS-indexed retractions increased after the reforms,the retraction rates for WoS articles remained stable.Post-reform reliance on MDPI journals,which have low retraction rates,partially explains this stability.Excluding MDPI publications,retraction rates for articles and reviews increase by 14.91%,aligning with patterns seen elsewhere.Research limitations:The study focuses on retractions involving Romanian authors,limiting its generalizability.Furthermore,reliance on database records may not fully capture all retractions.Practical implications:These findings underscore the need for research policy reforms to consider a broader range of effects,and the need for nuanced interpretations of retraction data,which are influenced by a complex range of factors,including specific publisher practices.Originality/value:This research is the first to investigate the complex relationship between research policy reforms,publisher behavior,and retraction trends.
文摘Following the publication,concerns have been raised about a number of figures in this article.The western blots in this article were presented with atypical,unusually shaped and possibly anomalous protein bands in many cases.
文摘The published article titled“MicroRNA-33b Inhibits the Proliferation andMigration of Osteosarcoma Cells via TargetingHypoxia-Inducible Factor-1α”has been retracted from Oncology Research,Vol.25,No.3,2017,pp.397–405.
文摘Following the publication,concerns have been raised about a number of figures in this article.An unexpected area of similarity was identified in terms of the cellular data,where the results from differently performed experiments were intended to have been shown,although the areas immediately surrounding this area featured comparatively different distributions of cells.In addition,the western blots in this article were presented with atypical,unusually shaped and possibly anomalous protein bands in many cases.
文摘The published article titled“UCA1 Regulates the Growth and Metastasis of Pancreatic Cancer by Sponging miR-135a”has been retracted from Oncology Research,Vol.25,No.9,2017,pp.1529–1541.DOI:10.3727/096504017X14888987683152 URL:https://www.techscience.com/or/v25n9/56938 Following the publication,concerns have been raised about a number of figures in this article.An unexpected area of similarity was identified in terms of the cellular data,where the results from differently performed experiments were intended to have been shown,although the areas immediately surrounding this area featured comparatively different distributions of cells.
文摘Traditionally,liver retraction for laparoscopic gastrectomy is done via manual methods,such as the placement of retractors through the accessory ports and using a Nathanson retractor.However,these techniques often posed issues including extra abdominal incisions,risk of liver injury or ischaemia,and the potential for compromised visualization.Over the years,the development of innovative liver retraction techniques has significantly improved the safety and efficacy of laparoscopic gastrectomy and similar other hiatal procedures.This editorial will comment on the article by Lin et al,and compare this to the other liver retractor techniques available for surgeons and highlight the pros and cons of each technique of liver retraction.
