Hot torsion tests for AZ80 magnesium alloy were carried out in the temperature range of 380℃-260℃,with a constant decreasing temperature rate of 10℃/s in order to weaken the basal texture and refine the grains.The ...Hot torsion tests for AZ80 magnesium alloy were carried out in the temperature range of 380℃-260℃,with a constant decreasing temperature rate of 10℃/s in order to weaken the basal texture and refine the grains.The results indicated that the average grain sizes were refined forming gradient structure with increasing specimen radial position from center(12.2-5.4μm),and that the initial basal texture intensity of the extruded magnesium alloy was weakened from 46.2 to 8.3.Furthermore,the extension twins(ETs)could be disintegrated from the twins forming separated twins with smaller sizes.Interestingly,ETs with the same twin variant intersecting with each other could be coalesced forming grains with similar orientation,while ETs with different twin variants were separated by twins boundaries contributing to grain refinement.Moreover,in addition to the conventional continuous dynamic recrystallized(CDRX)grains with 30˚orientation rotated around C-axis of the parent grains,CDRXed grains with 30˚rotation around a-axis and random rotation axis were also discerned.Besides,the CDRX evolution induced twins were also elaborated,exhibiting the complex competition between CDRX and twining.Hot torsion deformation with constant decreasing temperatures rate is an effective way of grain refinement and texture modification.展开更多
BACKGROUND Testicular torsion is the most common acute scrotum worldwide and mainly occurs in children and adolescents.Studies have demonstrated that the duration of symptoms and torsion grade lead to different outcom...BACKGROUND Testicular torsion is the most common acute scrotum worldwide and mainly occurs in children and adolescents.Studies have demonstrated that the duration of symptoms and torsion grade lead to different outcomes in children diagnosed with testicular torsion.AIM To predict the possibility of testicular salvage(TS)in patients with testicular torsion in a tertiary center.METHODS We reviewed the charts of 75 pediatric patients with acute testicular torsion during a 12-year period from November 2011 to July 2023 at the Suzhou Hospital of Anhui Medical University.Univariate and multivariate logistic regression analyses were used to determine independent predictors of testicular torsion.The data included clinical findings,physical examinations,laboratory data,color Doppler ultrasound findings,operating results,age,presenting institution status,and follow-up results.RESULTS Our study included 75 patients.TS was possible in 57.3%of all patients;testicular torsion occurred mostly in winter,and teenagers aged 11-15 years old accounted for 60%.Univariate logistic regression analyses revealed that younger age(P=0.09),body mass index(P=0.004),torsion angle(P=0.013),red blood cell count(P=0.03),neutrophil-to-lymphocyte ratio(P=0.009),and initial presenting institution(P<0.001)were associated with orchiectomy.In multivariate analysis,only the initial presenting institution predicted TS(P<0.05).CONCLUSION The initial presenting institution has a predictive value for predicting TS in patients with testicular torsion.Children with scrotal pain should be admitted to a tertiary hospital as soon as possible.展开更多
Purpose – This study aims to reduce the redundant weight of the anti-roll torsion bar brought by thetraditional empirical design and improving its strength and stiffness.Design/methodology/approach – Based on the fi...Purpose – This study aims to reduce the redundant weight of the anti-roll torsion bar brought by thetraditional empirical design and improving its strength and stiffness.Design/methodology/approach – Based on the finite element approach coupled with the improved belugawhale optimization (IBWO) algorithm, a collaborative optimization method is suggested to optimize the designof the anti-roll torsion bar structure and weight. The dimensions and material properties of the torsion bar weredefined as random variables, and the torsion bar’s mass and strength were investigated using finite elements.Then, chaotic mapping and differential evolution (DE) operators are introduced to improve the beluga whaleoptimization (BWO) algorithm and run case studies.Findings – The findings demonstrate that the IBWO has superior solution set distribution uniformity,convergence speed, solution correctness and stability than the BWO. The IBWO algorithm is used to optimizethe anti-roll torsion bar design. The error between the optimization and finite element simulation results wasless than 1%. The weight of the optimized anti-roll torsion bar was lessened by 4%, the maximum stress wasreduced by 35% and the stiffness was increased by 1.9%.Originality/value – The study provides a methodological reference for the simulation optimization process ofthe lateral anti-roll torsion bar.展开更多
BACKGROUND Cystic lymphangioma is a rare benign tumor that affects the lymphatic system.Mesenteric lymphangiomas in the small bowel are extremely uncommon.CASE SUMMARY We present a 21-year-old female patient who compl...BACKGROUND Cystic lymphangioma is a rare benign tumor that affects the lymphatic system.Mesenteric lymphangiomas in the small bowel are extremely uncommon.CASE SUMMARY We present a 21-year-old female patient who complained of abdominal pain.The diagnosis of ovarian torsion was suspected after abdominopelvic unenhanced computed tomography and ultrasound revealed a large cyst in contact with the bladder,ovary,and uterus.The patient underwent emergency laparotomy per-formed by gynecologists,but it was discovered that the cystic tumor originated from the jejunum.Gastrointestinal surgeons were then called in to perform a cystectomy.Pathological examination confirmed the diagnosis of cystic lymphangioma of the mesentery.The patient had an uneventful postoperative recovery.CONCLUSION Mesenteric lymphangiomas can cause abdominal pain,and imaging techniques can help determine their characteristics,location,and size.Complete surgical excision and pathological examination are considered the standard treatment and diagnostic method.展开更多
This paper aims to comprehensively analyze the influence of the principal stress angle rotation and intermediate principal stress on loess's strength and deformation characteristics.A hollow cylinder torsional she...This paper aims to comprehensively analyze the influence of the principal stress angle rotation and intermediate principal stress on loess's strength and deformation characteristics.A hollow cylinder torsional shear apparatus was utilized to conduct tests on remolded samples under both normal and frozen conditions to investigate the mechanical properties and deformation behavior of loess under complex stress conditions.The results indicate significant differences in the internal changes of soil particles,unfrozen water,and relative positions in soil samples under normal and frozen conditions,leading to noticeable variations in strength and strain development.In frozen state,loess experiences primarily compressive failure with a slow growth of cracks,while at normal temperature,it predominantly exhibits shear failure.With the increase in the principal stress angle,the deformation patterns of the soil samples under different conditions become essentially consistent,gradually transitioning from compression to extension,accompanied by a reduction in axial strength.The gradual increase in the principal stress axis angle(α)reduces the strength of the generalized shear stress and shear strain curves.Under an increasingα,frozen soil exhibits strain-hardening characteristics,with the maximum shear strength occurring atα¼45.The intermediate principal stress coefficient(b)also significantly impacts the strength of frozen soil,with an increasing b resulting in a gradual decrease in generalized shear stress strength.This study provides a reference for comprehensively exploring the mechanical properties of soil under traffic load and a reliable theoretical basis for the design and maintenance of roadbeds.展开更多
Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under trans...Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress due to bending and axial stress arising from constrained warping displacements at the fixing. The net shear stress distribution overlays the distributions from axial torsion and that from flexural shear under transverse loading. Both arise when transverse forces are displaced from the shear centre.展开更多
In this work,an as-rolled AZ31 square bar with c-axis//ND(normal direction)texture was used.Side-rolling and reciprocating torsion were performed to treat the bar.Microstructure evolution and tensile-compressive prope...In this work,an as-rolled AZ31 square bar with c-axis//ND(normal direction)texture was used.Side-rolling and reciprocating torsion were performed to treat the bar.Microstructure evolution and tensile-compressive properties were investigated in detail.Initial rolled AZ31 bar exhibits a large yield asymmetry along the rolling direction(RD).Reciprocating torsion can generate extension twins to introduce twin boundaries and twin-texture.The twin structure can reduce yield asymmetry.However,only limited regions in the rolled AZ31 bar can be twinned during torsion.Pre-side-rolling along the transverse direction(TD)can generate two texture components(c-axis//TD texture and c-axis//ND texture)by introducing profuse{10–12}twins.Such dual texture components help increase the regions which are favorable for twinning during torsion.Finally,combining side-rolling and reciprocating torsion generates hybrid{10–12}twins structure on the entire cross-section,resulting in a remarkably low yield asymmetry.The relevant mechanisms were discussed in detail.展开更多
Hydroformed parts are widely used in industrial automotive parts because of their higher stiffness and fatigue strength and reduced weight relative to their corresponding cast and welded parts.This paper reports a hyd...Hydroformed parts are widely used in industrial automotive parts because of their higher stiffness and fatigue strength and reduced weight relative to their corresponding cast and welded parts.This paper reports a hydraulicforming experimental platform for rectangular tube fittings that was constructed to conduct an experiment on the hydraulic forming of rectangular tube fittings.A finite element model was established on the basis of the fluid–solid coupling method and simulation analysis.The correctness of the simulation analysis and the feasibility of the fluid–solid coupling method for hydraulic forming simulation analysis were verified by comparing the experimental results with the simulation results.On the basis of the simulation analysis of the hydraulic process of the torsion beam using the fluid–solid coupling method,a sliding mold suitable for the hydroforming of torsion beams was designed for its structural characteristics.The effects of fluid characteristics,shaping pressure,axial feed rate,and friction coefficient on the wall thicknesses of torsions beams during formation were investigated.Fluid movement speed was related to tube deformation.Shaping pressure had a significant effect on rounded corners and straight edges.The axial feed speed was increased,and the uneven distribution of wall thicknesses was effectively improved.Although the friction coefficient had a nonsignificant effect on the wall thickness of the ladder-shaped region,it had a significant influence on a large deformation of wall thickness in the V-shaped area.In this paper,a method of fluid-solid coupling simulation analysis and sliding die is proposed to study the high pressure forming law in torsion beam.展开更多
As key components connecting offshore floating production platforms and subsea imports, offshore flexible pipes play significant roles in oil, natural gas, and water injection. It is found that torsional failure is on...As key components connecting offshore floating production platforms and subsea imports, offshore flexible pipes play significant roles in oil, natural gas, and water injection. It is found that torsional failure is one of the failure modes of flexible pipes during transportation and laying. In this paper, a theoretical model(TM) of a flexible pipe section mechanics is established, in which the carcass layer and the pressure armor layer are equivalent to the orthogonal anisotropic layers due to its complex cross-section structure. The calculation results of the TM are consistent with those of a finite element model(FEM), which can accurately describe the torsional response of the flexible pipe.Subsequently, the TM and FEM are used to discuss the influence of boundary conditions on the torsional response.The structure of the flexible pipe is stable when twisted counterclockwise. However, limiting the top axial displacement can improve the axial and radial instability of the tensile armor layer when twisted clockwise. Finally, it is recommended that the flexible pipe can be kept under top fixation during service or installation to avoid torsional failure.展开更多
Introduction: Torsion of the spermatic cord (TSC) is a serious surgical emergency because it is responsible for acute ischemia that can lead to the loss of the testicle. Very few studies have been carried out in C?te ...Introduction: Torsion of the spermatic cord (TSC) is a serious surgical emergency because it is responsible for acute ischemia that can lead to the loss of the testicle. Very few studies have been carried out in C?te d’Ivoire and particularly in Bouaké, on torsion of the testicle. The general objective of this work was to describe the epidemiological, diagnostic and therapeutic aspects of testicular torsion in our context. Materials and Methods: This is a retrospective study on 46 patients received urgently at the Teaching Hospital of Bouaké over a period of nine (9) years from December 01, 2010 to November 30, 2019 for torsion of the spermatic cord in adults. Results: The mean age of patients was 26.6 years with extremes of 17 to 41 years. 33 patients were seen before the sixth hour and 13 beyond. Scrotal pain, swelling of the hemibursa and testicular ascent were the dominant physical signs. Orchiectomy + contralateral testicular fixation was performed in 11 patients (23.9%). The average length of hospital stay was three (3) days. The immediate post-operative follow-up was simple. Late complications were marked by two testicular atrophy. Conclusion: Our series was marked by a high rate of orchiectomy. Actions to raise caregivers’ awareness of the population must be carried out so that they consult quickly in front of any painful stock market board to avoid the delay in diagnosis and management detrimental to the vitality of the torsional testicle.展开更多
In Tian Qin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic pro...In Tian Qin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic properties. Here we present a single frequency modulation method based on a torsion pendulum to measure the remanent magnetic moment mr of 1.1 kg dummy copper test mass, and the measurement result is(6.45 ± 0.04(stat) ± 0.07(syst)) × 10^(-8)A · m^(2). The measurement precision of the mr is about 0.9 n A · m^(2), well below the present measurement requirement of Tian Qin. The method is particularly useful for measuring extremely low magnetic properties of the materials for use in the construction of space-borne gravitational wave detection and other precision scientific apparatus.展开更多
Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with exc...Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with excellent lattice torsions and grain boundaries for highly efficient water splitting.According to the microstructural investigations and theoretical calculations,the lattice torsion interface not only contributes to the exposure of more active sites but also effectively tunes the adsorption energy of hydrogen/oxygen intermediates via the accumulation of charge redistribution.As a result,the Fe_(2)P-Co_(2)P heterostructure nanowire array exhibits exceptional bifunctional catalytic activity with overpotentials of 65 and 198 mV at 10 mA cm^(-2) for hydrogen and oxygen evolution reactions,respectively.Moreover,the Fe_(2)P-Co_(2)P/NF-assembled electrolyzer can deliver 10 mA cm^(-2) at an ultralow voltage of1.51 V while resulting in a high solar-to-hydrogen conversion efficiency of 19.8%in the solar-driven water electrolysis cell.展开更多
Introduction: Torsion of the spermatic cord is an emergency whose delay in treatment conditions the functional prognosis of the testicle. The aim of this study was to analyze the management of spermatic cord torsion i...Introduction: Torsion of the spermatic cord is an emergency whose delay in treatment conditions the functional prognosis of the testicle. The aim of this study was to analyze the management of spermatic cord torsion in the Urology Andrology Department of the Ignace Deen National Hospital in Conakry. Material and methods: This was a ten-year retrospective descriptive study from January 1, 2012 to December 31, 2021. It involved all patients admitted for torsion of the spermatic cord, confirmed at surgical exploration. Results: We identified 21 cases of torsion of the spermatic cord. The mean age of the patients was 17.9 ± 4.4 years. The average consultation time was 19.2 ± 21.4 hours with extremes of [2 h and 98 h]. Only 6 patients (28.6%) consulted before the sixth hour. All patients presented with scrotal swelling. At scrototomy, all torsions were intravaginal with two turns of spiral in 13 cases and three turns in 8 cases. Orchiectomy followed by contralateral orchidopexy was performed in 6 cases. In the other cases, bilateral orchidopexy was performed after detorsion. The average hospital stay was 4.5 days. We recorded 4 cases of testicular atrophy after orchidopexy. Conclusion: Spermatic cord torsion is an infrequent emergency in our department. The delay in consultation remains the main predictive factor of testicular necrosis. Emergency exploratory scrotomy should be the rule.展开更多
The design of hydro-bulge molds,able to provide hollow parts with special-shaped cross-sections,is still a pretty complicated task(especially for what concerns the design of the related hydraulic system and its“synch...The design of hydro-bulge molds,able to provide hollow parts with special-shaped cross-sections,is still a pretty complicated task(especially for what concerns the design of the related hydraulic system and its“synchronization”).In the present work,this task is addressed through the introduction of a new type of overhead cylinder hydraulic synchronization system,able to correct automatically any deviation from the optimal process.Using the AMESim software,the displacement synchronization curve of the piston rods of the two cylinders is obtained and it is verified that the system is able to implement an automatic deviation correction function by adjusting the bidirectional servo valve.A mathematical model for the synchronization system is presented,and the transfer function of the closed-loop control system is determined accordingly.The results show that the system response is generated at about 0.1∼0.2 s with the system reaching an equilibrium state at about 0.2 s.展开更多
A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt.%) alloy is processed by solution treatment and high pressure torsion(HPT) at room temperature to produce a nanostructured light material with high hardness. The stability of this alloy ...A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt.%) alloy is processed by solution treatment and high pressure torsion(HPT) at room temperature to produce a nanostructured light material with high hardness. The stability of this alloy is subsequently tested through isochronal annealing for 0.5 h at 373 K to 673 K. The results reveal a thermal stability that is vastly superior to that of conventional Mg-based alloys processed by severe plastic deformation: the grain size remains at around 50 nm on heating to 573 K, and as the temperature is increased to 673 K,grain growth is restricted to within 500 nm. The stability of grain refinement of the present alloy/processing combination allowing grain size to be limited to 55 nm after exposure at 573 K, appears to be nearly one order of magnitude better than for the other SPD processed Mg-RE type alloys, and 2 orders of magnitude better than those of SPD processed RE-free Mg alloys. This superior thermal stability is attributed to formation of co-clusters near and segregation at grain boundaries, which cause a thermodynamic stabilization of grain size, as well as formation of β-Mg_(5)RE equilibrium phase at grain boundaries, which impede grain growth by the Zener pinning effect. The hardness of the nanostructured Mg-Gd-Y-Zn-Zr alloy increases with increasing annealing temperature up to 573 K, which is quite different from the other SPD-processed Mg-based alloys. The high hardness of 136 HV after annealing at 573 K is mainly due to solute segregation and solute clustering at or near grain boundaries.展开更多
Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented ...Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented in this study.In the thickness direction,the GEC layers of the conical shell are ordered in a piece-wise arrangement of functionally graded(FG)distribution,with each layer containing a variable volume fraction for graphene reinforcement.To calculate the properties of temperaturedependent material of GEC layers,the extended Halpin-Tsai micromechanical framework is used.The FEM model is verified via comparing the current results obtained with the theoretical estimates for homogeneous,laminated cylindrical,and conical shells,the FEM model is validated.The computational results show that a piece-wise FG graphene volume fraction distribution can improve the torque of critical buckling and torsional postbuckling strength.Also,the geometric parameters have a critical impact on the stability of the conical shell.However,a temperature rise can reduce the crucial torsional buckling torque as well as the GEC laminated truncated conical shell’s postbuckling strength.展开更多
BACKGROUND Testicular torsion is an emergent disease in urology,and there has been discussion of the treatment of testicular torsion.Testicular decompression has been established as a critical treatment for testicular...BACKGROUND Testicular torsion is an emergent disease in urology,and there has been discussion of the treatment of testicular torsion.Testicular decompression has been established as a critical treatment for testicular compartment syndrome(TCS),which occurs after detorsion in a patient who is diagnosed with testis torsion.Until now,testicular fasciotomy and incision of tunica albuginea with tunica vaginalis flap(TVF)graft have been suggested for decompression,and some studies about the efficacy of TVF were reported.However,this method is time consuming and needs meticulous technique,so other methods such as orchio-septopexy are suggested.The objective of this clinical case report was to propose new surgical method using collagen fleece(Tachosil®)instead of tunica vagina flap.CASE SUMMARY A 5-year-old boy with scrotal pain visited our hospital 24 h after symptom onset.After history taking,physical examination,and scrotum ultrasonography,he was diagnosed with testis torsion.Emergency surgery was performed after diagnosis.Following the incision of scrotum and fasciotomy,we covered his tunica albuginea with collagen fleece called Tachosil®instead of covering with TVF.CONCLUSION Short-term follow-up showed normal blood flow in testis without a TCS.This is the first case report of using Tachosil®in testicular torsion surgery,and its advantages were already reported in other surgeries like Peyronie’s disease.Our case suggests this new technique is an appropriate method because of its advantages including its cost-effective and time-saving characteristics.The main limitation is the short follow-up,so more studies are needed to provide a high level of evidence about its efficacy and safety.展开更多
BACKGROUND Wandering spleen is rare clinically.It is characterized by displacement of the spleen in the abdominal and pelvic cavities and can have congenital or acquired causes.Wandering spleen involves serious compli...BACKGROUND Wandering spleen is rare clinically.It is characterized by displacement of the spleen in the abdominal and pelvic cavities and can have congenital or acquired causes.Wandering spleen involves serious complications,such as spleen torsion.The clinical symptoms range from asymptomatic abdominal mass to acute abdominal pain.Surgery is required after diagnosis.Cases of wandering spleen torsion with portal vein thrombosis(PVT)are rare.There is no report on how to eliminate PVT in such cases.CASE SUMMARY Ultrasound and computed tomography revealed a diagnosis of wandering spleen torsion with PVT in a 31-year-old woman with a history of childbirth 16 mo previously who received emergency treatment for upper abdominal pain.She recovered well after splenectomy and portal vein thrombectomy combined with continuous anticoagulation,and the PVT disappeared.CONCLUSION Rare and nonspecific conditions,such as wandering splenic torsion with PVT,must be diagnosed and treated early.Patients with complete splenic infarction require splenectomy.Anticoagulation therapy and individualized management for PVT is feasible.展开更多
Let 0<γ<π be a fixed pythagorean angle. We study the abelian group Hr of primitive integral triangles (a,b,c) for which the angle opposite side c is γ. Addition in Hr is defined by adding the angles β opposi...Let 0<γ<π be a fixed pythagorean angle. We study the abelian group Hr of primitive integral triangles (a,b,c) for which the angle opposite side c is γ. Addition in Hr is defined by adding the angles β opposite side b and modding out by π-γ. The only Hr for which the structure is known is Hπ/2, which is free abelian. We prove that for generalγ, Hr has an element of order two iff 2(1- cosγ) is a rational square, and it has elements of order three iff the cubic (2cosγ)x3-3x2+1=0 has a rational solution 0<x<1. This shows that the set of values ofγ for which Hr has two-torsion is dense in [0, π], and similarly for three-torsion. We also show that there is at most one copy of either Z2 or Z3 in Hr. Finally, we give some examples of higher order torsion elements in Hr.展开更多
基金supported by key technology research and development project of ShanXi province(20201102019)Natural science foundation of Shanxi Province(201901D111167)+2 种基金Shanxi Scholarship Council of China(2020-117)JCKY2018408B003Magnesium alloy high-performance XXX multi-directional extrusion technologyXX supporting scientific research project(xxxx-2019-021).
文摘Hot torsion tests for AZ80 magnesium alloy were carried out in the temperature range of 380℃-260℃,with a constant decreasing temperature rate of 10℃/s in order to weaken the basal texture and refine the grains.The results indicated that the average grain sizes were refined forming gradient structure with increasing specimen radial position from center(12.2-5.4μm),and that the initial basal texture intensity of the extruded magnesium alloy was weakened from 46.2 to 8.3.Furthermore,the extension twins(ETs)could be disintegrated from the twins forming separated twins with smaller sizes.Interestingly,ETs with the same twin variant intersecting with each other could be coalesced forming grains with similar orientation,while ETs with different twin variants were separated by twins boundaries contributing to grain refinement.Moreover,in addition to the conventional continuous dynamic recrystallized(CDRX)grains with 30˚orientation rotated around C-axis of the parent grains,CDRXed grains with 30˚rotation around a-axis and random rotation axis were also discerned.Besides,the CDRX evolution induced twins were also elaborated,exhibiting the complex competition between CDRX and twining.Hot torsion deformation with constant decreasing temperatures rate is an effective way of grain refinement and texture modification.
基金Supported by Anhui Province Translational Medicine Research Fund Project,No.2021zhyx-C59 and No.2021zhyx-C75.
文摘BACKGROUND Testicular torsion is the most common acute scrotum worldwide and mainly occurs in children and adolescents.Studies have demonstrated that the duration of symptoms and torsion grade lead to different outcomes in children diagnosed with testicular torsion.AIM To predict the possibility of testicular salvage(TS)in patients with testicular torsion in a tertiary center.METHODS We reviewed the charts of 75 pediatric patients with acute testicular torsion during a 12-year period from November 2011 to July 2023 at the Suzhou Hospital of Anhui Medical University.Univariate and multivariate logistic regression analyses were used to determine independent predictors of testicular torsion.The data included clinical findings,physical examinations,laboratory data,color Doppler ultrasound findings,operating results,age,presenting institution status,and follow-up results.RESULTS Our study included 75 patients.TS was possible in 57.3%of all patients;testicular torsion occurred mostly in winter,and teenagers aged 11-15 years old accounted for 60%.Univariate logistic regression analyses revealed that younger age(P=0.09),body mass index(P=0.004),torsion angle(P=0.013),red blood cell count(P=0.03),neutrophil-to-lymphocyte ratio(P=0.009),and initial presenting institution(P<0.001)were associated with orchiectomy.In multivariate analysis,only the initial presenting institution predicted TS(P<0.05).CONCLUSION The initial presenting institution has a predictive value for predicting TS in patients with testicular torsion.Children with scrotal pain should be admitted to a tertiary hospital as soon as possible.
基金funded by the National Natural Science Foundation of China(No:51875073)China RAILWAY(No:K2021J042).
文摘Purpose – This study aims to reduce the redundant weight of the anti-roll torsion bar brought by thetraditional empirical design and improving its strength and stiffness.Design/methodology/approach – Based on the finite element approach coupled with the improved belugawhale optimization (IBWO) algorithm, a collaborative optimization method is suggested to optimize the designof the anti-roll torsion bar structure and weight. The dimensions and material properties of the torsion bar weredefined as random variables, and the torsion bar’s mass and strength were investigated using finite elements.Then, chaotic mapping and differential evolution (DE) operators are introduced to improve the beluga whaleoptimization (BWO) algorithm and run case studies.Findings – The findings demonstrate that the IBWO has superior solution set distribution uniformity,convergence speed, solution correctness and stability than the BWO. The IBWO algorithm is used to optimizethe anti-roll torsion bar design. The error between the optimization and finite element simulation results wasless than 1%. The weight of the optimized anti-roll torsion bar was lessened by 4%, the maximum stress wasreduced by 35% and the stiffness was increased by 1.9%.Originality/value – The study provides a methodological reference for the simulation optimization process ofthe lateral anti-roll torsion bar.
文摘BACKGROUND Cystic lymphangioma is a rare benign tumor that affects the lymphatic system.Mesenteric lymphangiomas in the small bowel are extremely uncommon.CASE SUMMARY We present a 21-year-old female patient who complained of abdominal pain.The diagnosis of ovarian torsion was suspected after abdominopelvic unenhanced computed tomography and ultrasound revealed a large cyst in contact with the bladder,ovary,and uterus.The patient underwent emergency laparotomy per-formed by gynecologists,but it was discovered that the cystic tumor originated from the jejunum.Gastrointestinal surgeons were then called in to perform a cystectomy.Pathological examination confirmed the diagnosis of cystic lymphangioma of the mesentery.The patient had an uneventful postoperative recovery.CONCLUSION Mesenteric lymphangiomas can cause abdominal pain,and imaging techniques can help determine their characteristics,location,and size.Complete surgical excision and pathological examination are considered the standard treatment and diagnostic method.
基金This work was supported by the National Natural Science Foundation of China(Nos.42161026&41801046)the Natural Science Foundation of Qinghai Province(No.2023-ZJ-934M)the Youth Research Foundation of Qinghai University(No.2022-QGY-5).
文摘This paper aims to comprehensively analyze the influence of the principal stress angle rotation and intermediate principal stress on loess's strength and deformation characteristics.A hollow cylinder torsional shear apparatus was utilized to conduct tests on remolded samples under both normal and frozen conditions to investigate the mechanical properties and deformation behavior of loess under complex stress conditions.The results indicate significant differences in the internal changes of soil particles,unfrozen water,and relative positions in soil samples under normal and frozen conditions,leading to noticeable variations in strength and strain development.In frozen state,loess experiences primarily compressive failure with a slow growth of cracks,while at normal temperature,it predominantly exhibits shear failure.With the increase in the principal stress angle,the deformation patterns of the soil samples under different conditions become essentially consistent,gradually transitioning from compression to extension,accompanied by a reduction in axial strength.The gradual increase in the principal stress axis angle(α)reduces the strength of the generalized shear stress and shear strain curves.Under an increasingα,frozen soil exhibits strain-hardening characteristics,with the maximum shear strength occurring atα¼45.The intermediate principal stress coefficient(b)also significantly impacts the strength of frozen soil,with an increasing b resulting in a gradual decrease in generalized shear stress strength.This study provides a reference for comprehensively exploring the mechanical properties of soil under traffic load and a reliable theoretical basis for the design and maintenance of roadbeds.
文摘Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress due to bending and axial stress arising from constrained warping displacements at the fixing. The net shear stress distribution overlays the distributions from axial torsion and that from flexural shear under transverse loading. Both arise when transverse forces are displaced from the shear centre.
基金supported by the National Natural Science Foundation of China,No.51601154。
文摘In this work,an as-rolled AZ31 square bar with c-axis//ND(normal direction)texture was used.Side-rolling and reciprocating torsion were performed to treat the bar.Microstructure evolution and tensile-compressive properties were investigated in detail.Initial rolled AZ31 bar exhibits a large yield asymmetry along the rolling direction(RD).Reciprocating torsion can generate extension twins to introduce twin boundaries and twin-texture.The twin structure can reduce yield asymmetry.However,only limited regions in the rolled AZ31 bar can be twinned during torsion.Pre-side-rolling along the transverse direction(TD)can generate two texture components(c-axis//TD texture and c-axis//ND texture)by introducing profuse{10–12}twins.Such dual texture components help increase the regions which are favorable for twinning during torsion.Finally,combining side-rolling and reciprocating torsion generates hybrid{10–12}twins structure on the entire cross-section,resulting in a remarkably low yield asymmetry.The relevant mechanisms were discussed in detail.
基金Natural Science Foundation of China(Grant No.81960332)Guangxi Provincial Innovation driven Development Project(Grant No.GKAA17204062)+1 种基金Guangxi Provincial Natural Science Foundation(Grant No.2016GXNSFAA380211)Liuzhou Municipal Scientific Research and Technology Development Plan(Grant No.2016C050203)。
文摘Hydroformed parts are widely used in industrial automotive parts because of their higher stiffness and fatigue strength and reduced weight relative to their corresponding cast and welded parts.This paper reports a hydraulicforming experimental platform for rectangular tube fittings that was constructed to conduct an experiment on the hydraulic forming of rectangular tube fittings.A finite element model was established on the basis of the fluid–solid coupling method and simulation analysis.The correctness of the simulation analysis and the feasibility of the fluid–solid coupling method for hydraulic forming simulation analysis were verified by comparing the experimental results with the simulation results.On the basis of the simulation analysis of the hydraulic process of the torsion beam using the fluid–solid coupling method,a sliding mold suitable for the hydroforming of torsion beams was designed for its structural characteristics.The effects of fluid characteristics,shaping pressure,axial feed rate,and friction coefficient on the wall thicknesses of torsions beams during formation were investigated.Fluid movement speed was related to tube deformation.Shaping pressure had a significant effect on rounded corners and straight edges.The axial feed speed was increased,and the uneven distribution of wall thicknesses was effectively improved.Although the friction coefficient had a nonsignificant effect on the wall thickness of the ladder-shaped region,it had a significant influence on a large deformation of wall thickness in the V-shaped area.In this paper,a method of fluid-solid coupling simulation analysis and sliding die is proposed to study the high pressure forming law in torsion beam.
基金financially supported by the Natural Science Starting Project of SWPU (Grant No. 2022QHZ002)Sichuan Natural Science Foundation Youth Fund Project (Grant No. 2023NSFC0918)。
文摘As key components connecting offshore floating production platforms and subsea imports, offshore flexible pipes play significant roles in oil, natural gas, and water injection. It is found that torsional failure is one of the failure modes of flexible pipes during transportation and laying. In this paper, a theoretical model(TM) of a flexible pipe section mechanics is established, in which the carcass layer and the pressure armor layer are equivalent to the orthogonal anisotropic layers due to its complex cross-section structure. The calculation results of the TM are consistent with those of a finite element model(FEM), which can accurately describe the torsional response of the flexible pipe.Subsequently, the TM and FEM are used to discuss the influence of boundary conditions on the torsional response.The structure of the flexible pipe is stable when twisted counterclockwise. However, limiting the top axial displacement can improve the axial and radial instability of the tensile armor layer when twisted clockwise. Finally, it is recommended that the flexible pipe can be kept under top fixation during service or installation to avoid torsional failure.
文摘Introduction: Torsion of the spermatic cord (TSC) is a serious surgical emergency because it is responsible for acute ischemia that can lead to the loss of the testicle. Very few studies have been carried out in C?te d’Ivoire and particularly in Bouaké, on torsion of the testicle. The general objective of this work was to describe the epidemiological, diagnostic and therapeutic aspects of testicular torsion in our context. Materials and Methods: This is a retrospective study on 46 patients received urgently at the Teaching Hospital of Bouaké over a period of nine (9) years from December 01, 2010 to November 30, 2019 for torsion of the spermatic cord in adults. Results: The mean age of patients was 26.6 years with extremes of 17 to 41 years. 33 patients were seen before the sixth hour and 13 beyond. Scrotal pain, swelling of the hemibursa and testicular ascent were the dominant physical signs. Orchiectomy + contralateral testicular fixation was performed in 11 patients (23.9%). The average length of hospital stay was three (3) days. The immediate post-operative follow-up was simple. Late complications were marked by two testicular atrophy. Conclusion: Our series was marked by a high rate of orchiectomy. Actions to raise caregivers’ awareness of the population must be carried out so that they consult quickly in front of any painful stock market board to avoid the delay in diagnosis and management detrimental to the vitality of the torsional testicle.
基金supported by the National Key R&D Program of China (Grant No. 2020YFC2200500)the National Natural Science Foundation of China (Grant Nos. 12075325, 12005308, and 11605065)。
文摘In Tian Qin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic properties. Here we present a single frequency modulation method based on a torsion pendulum to measure the remanent magnetic moment mr of 1.1 kg dummy copper test mass, and the measurement result is(6.45 ± 0.04(stat) ± 0.07(syst)) × 10^(-8)A · m^(2). The measurement precision of the mr is about 0.9 n A · m^(2), well below the present measurement requirement of Tian Qin. The method is particularly useful for measuring extremely low magnetic properties of the materials for use in the construction of space-borne gravitational wave detection and other precision scientific apparatus.
基金financially supported by the National Natural Science Foundation of China(U2002213)the Creative Project of Engineering Research Center of Alternative Energy Materials&Devices,Ministry of Education,Sichuan University(AEMD202207)+7 种基金the Open Foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials of Guangxi University(2022GXYSOF10)the Guangdong Colleges&Universities Characteristic Innovation Project(2021KTSCX263)the Guangdong Education&Scientific Research Project(2021GXJK535)the Guangzhou Panyu Polytechnic Science&Technology Project(2021KJ01)the East-Land Middle-aged and Young Backbone Teacher of Yunnan University(C176220200)the Yunnan Applied Basic Research Projects(202001BB050006,202001BB050007)the Double Tops Joint Fund of the Yunnan Science and Technology Bureau and Yunnan University(2019FY003025)the Double First Class University Plan(C176220100042)。
文摘Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with excellent lattice torsions and grain boundaries for highly efficient water splitting.According to the microstructural investigations and theoretical calculations,the lattice torsion interface not only contributes to the exposure of more active sites but also effectively tunes the adsorption energy of hydrogen/oxygen intermediates via the accumulation of charge redistribution.As a result,the Fe_(2)P-Co_(2)P heterostructure nanowire array exhibits exceptional bifunctional catalytic activity with overpotentials of 65 and 198 mV at 10 mA cm^(-2) for hydrogen and oxygen evolution reactions,respectively.Moreover,the Fe_(2)P-Co_(2)P/NF-assembled electrolyzer can deliver 10 mA cm^(-2) at an ultralow voltage of1.51 V while resulting in a high solar-to-hydrogen conversion efficiency of 19.8%in the solar-driven water electrolysis cell.
文摘Introduction: Torsion of the spermatic cord is an emergency whose delay in treatment conditions the functional prognosis of the testicle. The aim of this study was to analyze the management of spermatic cord torsion in the Urology Andrology Department of the Ignace Deen National Hospital in Conakry. Material and methods: This was a ten-year retrospective descriptive study from January 1, 2012 to December 31, 2021. It involved all patients admitted for torsion of the spermatic cord, confirmed at surgical exploration. Results: We identified 21 cases of torsion of the spermatic cord. The mean age of the patients was 17.9 ± 4.4 years. The average consultation time was 19.2 ± 21.4 hours with extremes of [2 h and 98 h]. Only 6 patients (28.6%) consulted before the sixth hour. All patients presented with scrotal swelling. At scrototomy, all torsions were intravaginal with two turns of spiral in 13 cases and three turns in 8 cases. Orchiectomy followed by contralateral orchidopexy was performed in 6 cases. In the other cases, bilateral orchidopexy was performed after detorsion. The average hospital stay was 4.5 days. We recorded 4 cases of testicular atrophy after orchidopexy. Conclusion: Spermatic cord torsion is an infrequent emergency in our department. The delay in consultation remains the main predictive factor of testicular necrosis. Emergency exploratory scrotomy should be the rule.
基金projects of“The University Synergy Innovation Program of Anhui Province(GXXT-2019-004)Teaching Research Project of Anhui Education DepartmentScience and Technology Planning Project of Wuhu City(2021YF58).”。
文摘The design of hydro-bulge molds,able to provide hollow parts with special-shaped cross-sections,is still a pretty complicated task(especially for what concerns the design of the related hydraulic system and its“synchronization”).In the present work,this task is addressed through the introduction of a new type of overhead cylinder hydraulic synchronization system,able to correct automatically any deviation from the optimal process.Using the AMESim software,the displacement synchronization curve of the piston rods of the two cylinders is obtained and it is verified that the system is able to implement an automatic deviation correction function by adjusting the bidirectional servo valve.A mathematical model for the synchronization system is presented,and the transfer function of the closed-loop control system is determined accordingly.The results show that the system response is generated at about 0.1∼0.2 s with the system reaching an equilibrium state at about 0.2 s.
基金supported by National Natural Science Foundation of China (No.U21A2047 and 51971076)China Postdoctoral Science Foundation (Grant No.2019M653599)Guangdong Basic and Applied Basic Research Foundation (No.2019A1515110289)。
文摘A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt.%) alloy is processed by solution treatment and high pressure torsion(HPT) at room temperature to produce a nanostructured light material with high hardness. The stability of this alloy is subsequently tested through isochronal annealing for 0.5 h at 373 K to 673 K. The results reveal a thermal stability that is vastly superior to that of conventional Mg-based alloys processed by severe plastic deformation: the grain size remains at around 50 nm on heating to 573 K, and as the temperature is increased to 673 K,grain growth is restricted to within 500 nm. The stability of grain refinement of the present alloy/processing combination allowing grain size to be limited to 55 nm after exposure at 573 K, appears to be nearly one order of magnitude better than for the other SPD processed Mg-RE type alloys, and 2 orders of magnitude better than those of SPD processed RE-free Mg alloys. This superior thermal stability is attributed to formation of co-clusters near and segregation at grain boundaries, which cause a thermodynamic stabilization of grain size, as well as formation of β-Mg_(5)RE equilibrium phase at grain boundaries, which impede grain growth by the Zener pinning effect. The hardness of the nanostructured Mg-Gd-Y-Zn-Zr alloy increases with increasing annealing temperature up to 573 K, which is quite different from the other SPD-processed Mg-based alloys. The high hardness of 136 HV after annealing at 573 K is mainly due to solute segregation and solute clustering at or near grain boundaries.
文摘Buckling and postbuckling characteristics of laminated graphene-enhanced composite(GEC)truncated conical shells exposed to torsion under temperature conditions using finite element method(FEM)simulation are presented in this study.In the thickness direction,the GEC layers of the conical shell are ordered in a piece-wise arrangement of functionally graded(FG)distribution,with each layer containing a variable volume fraction for graphene reinforcement.To calculate the properties of temperaturedependent material of GEC layers,the extended Halpin-Tsai micromechanical framework is used.The FEM model is verified via comparing the current results obtained with the theoretical estimates for homogeneous,laminated cylindrical,and conical shells,the FEM model is validated.The computational results show that a piece-wise FG graphene volume fraction distribution can improve the torque of critical buckling and torsional postbuckling strength.Also,the geometric parameters have a critical impact on the stability of the conical shell.However,a temperature rise can reduce the crucial torsional buckling torque as well as the GEC laminated truncated conical shell’s postbuckling strength.
基金Supported by The Soonchunhyang University Research Fund,No.20230029.
文摘BACKGROUND Testicular torsion is an emergent disease in urology,and there has been discussion of the treatment of testicular torsion.Testicular decompression has been established as a critical treatment for testicular compartment syndrome(TCS),which occurs after detorsion in a patient who is diagnosed with testis torsion.Until now,testicular fasciotomy and incision of tunica albuginea with tunica vaginalis flap(TVF)graft have been suggested for decompression,and some studies about the efficacy of TVF were reported.However,this method is time consuming and needs meticulous technique,so other methods such as orchio-septopexy are suggested.The objective of this clinical case report was to propose new surgical method using collagen fleece(Tachosil®)instead of tunica vagina flap.CASE SUMMARY A 5-year-old boy with scrotal pain visited our hospital 24 h after symptom onset.After history taking,physical examination,and scrotum ultrasonography,he was diagnosed with testis torsion.Emergency surgery was performed after diagnosis.Following the incision of scrotum and fasciotomy,we covered his tunica albuginea with collagen fleece called Tachosil®instead of covering with TVF.CONCLUSION Short-term follow-up showed normal blood flow in testis without a TCS.This is the first case report of using Tachosil®in testicular torsion surgery,and its advantages were already reported in other surgeries like Peyronie’s disease.Our case suggests this new technique is an appropriate method because of its advantages including its cost-effective and time-saving characteristics.The main limitation is the short follow-up,so more studies are needed to provide a high level of evidence about its efficacy and safety.
基金Supported by CACMS Innovation Fund,No.CI2021A03317.
文摘BACKGROUND Wandering spleen is rare clinically.It is characterized by displacement of the spleen in the abdominal and pelvic cavities and can have congenital or acquired causes.Wandering spleen involves serious complications,such as spleen torsion.The clinical symptoms range from asymptomatic abdominal mass to acute abdominal pain.Surgery is required after diagnosis.Cases of wandering spleen torsion with portal vein thrombosis(PVT)are rare.There is no report on how to eliminate PVT in such cases.CASE SUMMARY Ultrasound and computed tomography revealed a diagnosis of wandering spleen torsion with PVT in a 31-year-old woman with a history of childbirth 16 mo previously who received emergency treatment for upper abdominal pain.She recovered well after splenectomy and portal vein thrombectomy combined with continuous anticoagulation,and the PVT disappeared.CONCLUSION Rare and nonspecific conditions,such as wandering splenic torsion with PVT,must be diagnosed and treated early.Patients with complete splenic infarction require splenectomy.Anticoagulation therapy and individualized management for PVT is feasible.
文摘Let 0<γ<π be a fixed pythagorean angle. We study the abelian group Hr of primitive integral triangles (a,b,c) for which the angle opposite side c is γ. Addition in Hr is defined by adding the angles β opposite side b and modding out by π-γ. The only Hr for which the structure is known is Hπ/2, which is free abelian. We prove that for generalγ, Hr has an element of order two iff 2(1- cosγ) is a rational square, and it has elements of order three iff the cubic (2cosγ)x3-3x2+1=0 has a rational solution 0<x<1. This shows that the set of values ofγ for which Hr has two-torsion is dense in [0, π], and similarly for three-torsion. We also show that there is at most one copy of either Z2 or Z3 in Hr. Finally, we give some examples of higher order torsion elements in Hr.