Dynamic compressive response of porcine muscle measured using a split Hopkinson bar system with a pair of PVDF force transducers

The classic metallic Split Hopkinson Pressure Bar(SHPB)cannot capture the transmitted signal accurately when measuring soft biological tissue,because of the very low wave impedance and strength of this material.So the dynamic compressive response of porcine muscle has been investigated by using a modified SHPB.The forces on both ends of the sample measured using Polyvinylidene fluor(PVDF)transducers were applied to calculate the stress in the specimen instead of the strain gauge signal on the transmitted bar.Moreover,a circular cardboard disk pulse shaper was applied for generating a suitable incident pulse to achieve stress equilibrium and constant strain rates in the specimens.Then,the dynamic mechanical properties of porcine muscle parallel and perpendicular to the fiber directions were measured,and the stress equilibrium process during loading was analyzed,as well as the inertia-induced extra stress being corrected.Furthermore,quasi-static tests were conducted at two different strain rates to investigate the strain rate dependence using a universal material testing machine.The results show that the stress-strain curves are sensitive to strain rate in the two different loading directions.The compressive stress perpendicular to the fiber direction is stiffer than that parallel to the fiber direction.In addition,a strain rate-dependent constitutive model was developed based on the mechanical response of the muscle at different strain rates and fitted to the experimental data.The results show that the overall fit is good,and the constitutive model could describe the muscle's dynamic mechanical properties.

Risk factors related to postoperative recurrence of dermatofibrosarcoma protuberans: A retrospective study and literature review

BACKGROUND Dermatofibrosarcoma protuberans(DFSP)is a rare low-grade malignant soft tissue tumor characterized by rosette-like infiltrative growth.Postoperative recurrence of this tumor is very common.AIM To evaluate the risk factors related to recurrence after wide local excision(WLE)of DFSP and to guide clinical diagnosis and treatment.METHODS The medical records of 44 DFSP patients confirmed by pathology at our hospital from 2012 to 2019 were retrospectively reviewed.The relationship between clinical features,tumor characteristics,treatment,and recurrence risk were analyzed,and the possible risk factors for postoperative tumor recurrence were evaluated.RESULTS There were 44 patients in total,including 21 males and 23 females.The median progression free survival was 36 mo(range,1-240 mo).Twenty patients were treated for the first time,while 24 had previous treatment experience.Forty-two cases were followed for 25.76±22.0 mo,among whom four(9.52%)experienced recurrence after WLE(rate was 9.52%).The recurrence rate in the recurrent group was higher than that in the patients with primary tumor(19.05%vs 0%,P=0.028).Eighteen cases had a history of misdiagnosis(rate was 40.91%).The recurrence rate among patients with previous experience of misdiagnosis was significantly higher than in patients without(68%vs 36.84%,P=0.04).The tumor diameter in patients with a history of treatment was larger than in patients treated for the first time(4.75±0.70 cm vs 2.25±0.36 cm,P=0.004).CONCLUSION To sum up,the clinical manifestations of DFSP are not specific and are easily misdiagnosed,thus commonly causing the recurrence of DFSP.After incomplete resection,the tumor may rapidly grow.Previous recurrence history may be a risk factor for postoperative recurrence,and tumor location may have an indirect effect on postoperative recurrence;however,we found no significant correlation between sex,age,course of the disease,or tumor size and postoperative recurrence.

Experimental and numerical investigation on penetration of clay masonry by small high-speed projectile

This study investigates a kind of masonry consisting of clay-fired brick(f_(c)=10 MPa;r=1:38 g/cm^(3))and mortar(f_(c)=10 MPa;r=1:8 g/cm^(3)).Clay-fired brick masonry connotes a traditional construction material of old architecture and public buildings.We carried out penetration experiments in which four clay-fired brick walls employing two different patterns were subjected to impact from small high-speed projectile,i.e.12.7 mm armor-piercing explosive incendiary projectile and material tests in which the static and dynamic compressive strengths of clay-fired brick and mortar were determined by quasi-static and SHPB(Split Hopkinson Pressure Bar)tests.The experimental data include hit and exit velocities,damage configuration of clay brick masonry and mechanical properties of material at low and high strain rates,though which influence of thickness and bonding patterns of wall on kinetic loss of bullet,the damage patterns of masonry observed experimentally and dynamic increase of material strengths are analyzed.To keep minimum boundary inconsistency with reality,full 3D detailed finite element model consisting of two different material is established.Sharing common nodes and employing automatic tiebreak contact are combined to reduce computational time usage of large-scale model.For description of clay-fired brick and mortar RiedeleHiermaiereThoma(RHT)material model is employed.Material parameter set is derived based on experimental data,available literature and engineering assumptions.The numerical simulations study the mesh resolution dependency of material model,reproduce the crucial phenomena of masonry in experiment acceptably and offer more time-resolved insight into motion of bullet in the process of penetration.The feasibility of means of constructing finite element model and applying RHT model to the masonry herein and analogous constructions is explored through numerical investigation.

Chinese Expert Consensus on the Diagnosis and Treatment of Adult Dermatomyositis (2022)

Dermatomyositis,an idiopathic inflammatory myopathy,is characterized by distinctive skin manifestations,proximal muscle weakness,and multiple organ involvement and can be accompanied by malignancies.To provide a reference for dermatologists and clinicians in other relevant fields of clinical practice,experts from the Dermatology Branch of the China International Exchange and Promotion Association for Medical and Health Care and the National Clinical Research Center for Dermatologic and Immunologic Diseases developed this consensus on the diagnosis and treatment of adult dermatomyositis using Chinese and international literature and expert advice.

Expert Consensus on the Treat-to-Target Strategy for Psoriasis With Biological Agents in China(Simplified Edition)

Psoriasis is a chronic,recurrent,inflammatory systemic disease that is not only characterized by skin manifestations but may also be accompanied by various comorbidities,imposing a heavy burden on patients’physical and mental health and affecting their quality of life.Although the continuous approval of various biological agents for clinical use has provided more effective treatment options to patients with psoriasis,no consensus on the evaluation of comprehensive treatment goals has yet been established.The treat-to-target(T2T)strategy requires consideration of multiple dimensions of treatment outcomes,the development of long-term management goals,and regular assessments of treatment conditions,which are often used in the management of chronic diseases.Therefore,based on the latest consensuses and guidelines,research data,and clinical experience as well as the combination of survey results and expert group discussions,the present consensus focuses on 4 dimensions of short-and long-term integrated management goals for biological agents:alleviating skin lesions,improving quality of life,screening and managing psoriasis comorbidities,and ensuring drug safety.The implementation methods,evaluation time,treatment monitoring,and program adjustments are also herein described to achieve comprehensive management of psoriasis to the maximum extent.This consensus provides a reference for clinical practice.

A high-Nb-TiAl alloy with ultrafine-grained structure fabricated by cryomilling and spark plasma sintering

In this work,an ultrafine-grained high-Nb-TiAl alloy with a nominal composition of Ti-45Al-8Nb-0.2W-0.2B(at%)was prepared by cryomilling and subsequent spark plasma sintering(SPS)technique.The chemical composition,particle size,morphology and crystallite size of cryomilled powder were studied.It is found that cryomilling can effectively reduce the particle size and enhance grain refinement.The ingots sintered at 900 and 1000℃ show an equiaxed near-γmicrostructure with grain sizes<700 nm,while the sample sintered at 1100℃exhibits duplex microstructure.Especially,the one sintered at 1000℃ has excellent mechanical properties,whose compression yield strength,fracture strength,bending strength and plastic strain achieve 1310,2174,578 MPa and 16.8%,respectively.The reasons for the effect of cryomilling and the mechanical behavior of sintered ingots were discussed.It is suggested that cryomilling in combination with SPS is an effective way to synthesize high-NbTiAl alloy with ultrafine-grained structure.

Assessment of skin care behavior and cognition of patients with acne vulgaris in China

To the Editor:Acne vulgaris(AV)is a common skin disease mainly among adolescents with varying incidences around.the world,significantly affecting patients'facial appear:ance,psychology,social activity,and quality of life.[1]Many factors including genetic components,environmental elements,hormone levels,treatments,diets,and skin care-behavior are associated with an increased risk of AV.[2] Herein,we investigated AV patients'skin care behavior and cognition to predisposing factors with a designed clectronic questionnaire.