Surgical treatment of metastatic bone disease of the distal extremities

Metastatic bone disease of the distal extremities,also known as acrometastasis,is very rare.Thus,there is very limited information regarding the clinical manifestations and methods of surgical treatment.The current available literature shows that acrometastases are often encountered in the context of advanced disease and are thus associated with poor patient survival.As metastatic bone disease is generally uncurable,the goal of surgical treatment is to provide the patient with good function with as few complications as possible.In this article,we discuss the clinical manifestation of acrometastases,the methods of surgical intervention,and the expected clinical outcome.Non-surgically managed pathological fractures generally remain ununited;therefore,conservative treatment is reserved for patients with poor general condition or dismal prognosis.The current evidence suggests that in lesions of the lower arm and leg,osteosynthesis(plate and screw fixation or intramedullary nail)is the most common method of reconstruction,whereas local excision or amputation are more commonly used in cases of more distal lesions(such as ankle,foot and hand).Following surgery most patients receive adjuvant radiotherapy,even though its role is poorly documented.Close collaboration between orthopedic surgeons and medical oncologists is necessary to improve patient care and treatment outcome.Further studies are needed in order to provide stronger clinical evidence and improve decision-making,in an effort to optimize the patients’quality of life and avoid the need for revision surgery.

Motor relearning program and Bobath method improve motor function of the upper extremities in patients with stroke

BACKGROUND: In the natural evolution of cerebrovascular disease, unconscious use of affected extremity during drug treatment and daily life can improve the function of affected upper extremity partially, but it is very slow and also accompanied by the formation of abnormal mode. Therefore, functional training should be emphasized in recovering the motor function of extremity. OBJECTIVE: To observe the effects of combination of motor relearning program and Bobath method on motor function of upper extremity of patients with stroke. DESIGN: Comparison of therapeutic effects taking stroke patients as observation subjects. SETTING: Department of Neurology, General Hospital of Beijing Jingmei Group. PARTICIPANTS: Totally 120 stroke patients, including 60 males and 60 females, averaged (59±3) years, who hospitalized in the Department of Neurology, General Hospital of Beijing Jingmei Group between January 2005 and June 2006 were recruited. The involved patients met the following criteria: Stroke attack within 2 weeks; diagnosis criteria of cerebral hemorrhage or infarction made in the 4th National Cerebrovascular Disease Conference; confirmed by skull CT or MRI; Informed consents of therapeutic regimen were obtained. The patients were assigned into 2 groups according to their wills: rehabilitation group and control group, with 30 males and 30 females in each group. Patients in rehabilitation group averaged (59±2)years old, and those in the control group averaged (58±2)years old. METHODS: ① Patients in two groups received routine treatment in the Department of Neurology. When the vital signs of patients in the rehabilitation group were stable, individualized treatment was conducted by combined application of motor relearning program and Bobath method. Meanwhile, training of activity of daily living was performed according to the disease condition changes of patients at different phases, including the nursing and instruction of body posture, the maintenance of good extremity position, bed exercise, bedside sit up and sitting position balance, sit up exercise, dynamic and static balance exercise, walking exercise, active training and passive training. The strength, time and speed of training were increased gradually according to their physical abilities. Patients were trained 45 to 60 minutes once, 5 times a week, within 2 weeks. ② Evaluation criteria of therapeutic effect: The motor function of upper extremity was evaluated by Fugl-Meyer method on the day of beginning and end of treatment. Higher points indicated better function of upper extremity. ③ t test and paired t test were used for comparing the difference of intergroup and intragroup measurement data, respectively. MAIN OUTCOME MEASURES: Changes in Fugl-Meyer scoring of two groups before and after treatment. RESULTS: Totally 120 stroke patients participated in the final analysis. Before treatment, Fugl-Meyer scoring was close between rehabilitation group and control group [(14.47±2.38),(14.16±2.39) points, P > 0.05]; Fugl-Meyer scoring of rehabilitation group after treatment was significantly higher than that before treatment and that of control group[(37.93±2.67),(18.36±2.43) points, t =11.053, 5.408, P < 0.01]; There were no significant differences in Fugl-Meyer scoring between before treatment in the control group and control group (P > 0.05). CONCLUSION: Combined application of motor relearning program and Bobath method can significantly improve the motor function of upper extremity of patients with stroke.

Kinematic Analysis of the Neck and Upper Extremities During Walking in Healthy Young Adults

The objective of this paper is to quantify the local stabilities of the neck and upper extremities （right/left shoulders and right/left elbows）, and investigate differences between linear and nonlinear measurements of the associated joint motions and differences in the local stability between the upper and lower extremities. This attempt involves the calculation of a nonlinear parameter, Lyapunov Exponent （LE）, and a linear parameter, Range of Motion （ROM）, during treadmill walking in conj unction with a large population of healthy subjects. Joint motions of subjects were captured using a three-dimensional motion-capture system. Then mathematical chaos theory and the Rosenstein algorithm were employed to calculate LE of joints as the extent of logarithmic divergence between the neighboring state-space trajectories of flexion-extension angles. LEs computed over twenty males and twenty females were 0.037~0.023 for the neck, 0.043＋0.021 for the right shoulder, 0.045i0.030 for the left shoulder, 0.032i0.021 for the right elbow, and 0.034~0.026 for the left elbow. Although statistically significant difference in the ROM was observed between all pairs of the neck and upper extremity joints, differences in the LE between all pairs of the joints as well as between males and females were not statistically significant. Between the upper and lower extremities, LEs of the neck, shoulder, and elbow were significantly smaller than those of the hip （-0.064） and the knee （-0,062）. These results indicate that a statistical difference in the local stability between the upper extremity joints is not significant. However, the different result between the ROM and LE gives a strong rationale for applying both linear and nonlinear tools together to the evaluation of joint movement. The LEs of the joints calculated from a large population of healthy subjects could provide normative values for the associated joints and can be used to evaluate the recovery progress of patients with joint related diseases.

Clinical outcome after surgery on schwannomas in the extremities

BACKGROUND Schwannoma is a benign,encapsulated and slowly growing tumor originating from Schwann cells and is rarely seen in the peripheral nerve system.Typical symptoms are soreness,radiating pain and sensory loss combined with a soft tissue mass.AIM To evaluate pre-and postoperative symptoms in patients operated for schwannomas in the extremities and investigate the rate of malignant transformation.METHODS In this single center retrospective study design,all patients who had surgery for a benign schwannoma in the extremities from May 1997 to January 2018 were included.The location of the tumor in the extremities was divided into five groups;forearm,arm,shoulder,thigh and leg including foot.The locations of the tumor in the nerves were also categorized as either;proximal,distal,minor or major nerve.During the pre-and postoperative clinical evaluation,symptoms were classified as paresthesia,local pain,radiating pain,swelling,impairment of mobility/strength and asymptomatic tumors that were found incidentally(with magnetic resonance imaging).The patients were evaluated after surgery using the following categories:Asymptomatic or symptomatic patients(radiating and/or local pain)and those with complications.The follow up period was from the time of surgery until last examination of the particular physician.Multivariate logistic regression analysis was performed to identify independent prognostic factors for postoperative significant symptoms at follow-up.RESULTS We identified 858 cases from the institutional pathology register.We excluded cases with duplicate diagnoses(n=407),pathology not including schwannomas(n=157),lesions involving the torso,spine and neck(n=150)leaving 144 patients for further analysis.In this group 99 patients underwent surgery and there were five complications recorded:2 infections(treated with antibiotics)and 3 nerve palsies(2 involving the radial nerve and one involving the median nerve)that recovered spontaneously.At the end of follow-up,1.4 mo(range 0.5-76)postoperatively,we recorded a post-operative decrease in clinical symptoms:Local pain 76%(6/25),radiating pain 97%(2/45),swelling 20%(8/10).Symptoms of paresthesia increased by 2.8%(37/36)and there was no change in motor weakness before and after surgery 1%(1/1).Multivariate analysis showed that tumors located within minor nerves had a significantly higher prevalence of postoperative symptoms compared with tumors in major nerves(odds ratio:2.63;confidence intervals:1.22-6.42,P=0.029).One patient with schwannoma diagnosed by needle biopsy was diagnosed to have malignant transformation diagnosed in the surgically removed tumor.No local recurrences were reported.CONCLUSION Surgery of schwannomas can be conducted with low risk of postoperative complications,acceptable decrease in clinical symptoms and risk of malignant transformation is low.

Clinical and imaging features of desmoid tumors of the extremities

BACKGROUND Desmoid fibroma is a rare soft tissue tumor originating from the aponeurosis,fascia,and muscle,and it is also known as aponeurotic fibroma,invasive fibroma,or ligamentous fibroma.AIM To investigate the clinical and imaging features of desmoid tumors of the extremities.METHODS Thirteen patients with desmoid fibroma of the extremities admitted to our hospital from October 2016 to March 2021 were included.All patients underwent computed tomography(CT),magnetic resonance imaging(MRI),and pathological examination of the lesion.Data on the diameter and distribution of the lesion,the relationship between the lesion morphology and surrounding structures,MRI and CT findings,and pathological features were statistically analyzed.RESULTS The lesion diameter ranged from 1.7 to 8.9 cm,with an average of 5.35±2.39 cm.All lesions were located in the deep muscular space,with the left and right forearm each accounting for 23.08%of cases.Among the 13 patients with desmoid fibroma of the extremities,the lesions were"patchy"in 1 case,irregular in 10,and quasi-round in 2.The boundary between the lesion and surrounding soft tissue was blurred in 10 cases,and the focus infiltrated along the tissue space and invaded the adjacent structures.Furthermore,the edge of the lesion showed"beard-like"infiltration in 2 cases;bone resorption and damage were found in 8,and bending of the bone was present in 2;the boundary of the focus was clear in 1.According to the MRI examination,the lesions were larger than 5 cm(61.54%),round or fusiform in shape(84.62%),had an unclear boundary(76.92%),showed uniform signal(69.23%),inhomogeneous enhancement(84.62%),and"root"or"claw"infiltration(69.23%).Neurovascular tract invasion was present in 30.77%of cases.CT examination showed that the desmoid tumors had slightly a lower density(69.23%),higher enhancement(61.54%),and unclear boundary(84.62%);a CT value<50 Hu was present in 53.85%of lesions,and the enhancement was uneven in 53.85%of cases.Microscopically,fibroblasts and myofibroblasts were arranged in strands and bundles,without obvious atypia but with occasional karyotyping;cells were surrounded by collagen tissue.There were disparities in the proportion of collagen tissue in different regions,with abundant collagen tissue and few tumor cells in some areas,similar to the structure of aponeuroses or ligaments,and tumor cells invading the surrounding tissues.CONCLUSION Desmoid tumors of the extremities have certain imaging features on CT and MRI.The two imaging techniques can be combined to improve the diagnostic accuracy,achieve a comprehensive diagnosis of the disease in the clinical practice,and reduce the risk of missed diagnosis or misdiagnosis.In addition,their use can ensure timely diagnosis and treatment.

Meta analysis of clinical efficacy of combination of traditional Chinese and western medicine in the treatment of venous ulcer of lower extremities

Objective: To test the therapeutic effect of integrated traditional Chinese and western medicine on venous ulcer of lower limbs by Meta analysis method, and then to propose the best clinical treatment scheme. Methods: Domestic databases in the past 20 years (January 1999-December 2019) were searched by computer, including China Journal Full-text Database (CNKI), VIP, Wanfang and CBM. Literature was screened according to inclusion and exclusion criteria. Cochrane risk assessment tool was used to evaluate the quality of the included literature. Two-classification method was used to extract data. RevMan 5.3 software was used to make statistical analysis of the data. Results: Eleven articles were finally included, totaling 1,576 patients, 804 cases in the treatment group and 772 cases in the control group. Meta-analysis results show that there is no difference in heterogeneity and bias among the included literatures. The total effective rate (risk ratio [RR]=1.12, 95% confidence interval [CI]=1.09-1.15) of integrated traditional Chinese and western medicine in treating venous ulcer of lower limbs is higher, which is obviously better than that of western medicine alone. Conclusion: Through data analysis, it is concluded that in the study population, the treatment of integrated traditional Chinese and western medicine has a significant effect on venous ulcer of lower limbs. Make up for the deficiency of simple western medicine treatment, improve the cure rate and reduce the recurrence rate. However, there is currently a lack of relevant high-quality literature, so a large sample size, rigorous and standardized experimental design and randomized double-blind clinical study are needed to further test the conclusions.

Effect of Motor Relearning Combined with t DCS on Motor Function of Lower Extremities and Gait in Patients with Cerebral Infarction and 3D Gait Analysis

[Objectives]To observe the effect of motor relearning combined with transcranial direct current stimulation on the motor function of lower extremities in patients with cerebral infarction,and to observe its effect on gait by 3D gait analysis.[Methods]60 patients with cerebral infarction who met the inclusion criteria were randomly divided into 3 groups according to the order of treatment(n=20).Group A received motor relearning treatment,group B received transcranial direct current stimulation treatment,group C received motor relearning combined with transcranial direct current stimulation,and the curative effect was observed after 5 courses of treatment.[Results]Before treatment,FMA,MBI,spatio-temporal parameters for 3D gait analysis(gait frequency,gait cycle,stride length,gait speed,stride length deviation,double support)and lower limb joint motion parameters(affected side stride length,maximum hip flexion,maximum hip extension,maximum knee flexion,maximum knee extension,stance phase,swing phase)were compared among the three groups.After treatment,the FMA and MBI of the three groups increased,and the spatio-temporal parameters for 3D gait analysis(gait frequency,gait cycle,gait speed,double support)and the lower limb joint motion parameters(affected side stride length,maximum hip flexion,maximum hip extension,maximum knee flexion,swing phase)were all improved,while the spatio-temporal parameters(stride length and stride length deviation)and the lower limb joint motion parameters(maximum knee extension and stance phase)decreased.Compared with those before treatment,there were significant differences among the three groups(P<0.05).Through the comparison between groups,it was found that the FMA,MBI,spatio-temporal parameters for 3D gait analysis(gait frequency,gait cycle,gait speed,double support)and lower limb joint motion parameters(affected side stride length,maximum hip flexion,maximum hip extension,maximum knee flexion,swing phase)in group C were significantly higher than those in group A and B,while the spatio-temporal parameters(stride length and stride length deviation)and lower limb joint motion parameters(maximum knee extension and stance phase)in group C were significantly lower than those in group A and group B,and the difference was statistically significant(P<0.05).[Conclusions]Motor relearning combined with transcranial direct current stimulation could increase MBI and FMA,improve gait spatio-temporal parameters and lower limb joint motion parameters,and correct abnormal gait in patients with cerebral infarction.

Ongoing Blood Pressure Change in Both Upper Extremities: An Unusual Presentation of Aortic Dissection

Aortic dissection is a critical condition requiring immediate assessment and management. Patients with this condition usually present with severe chest pain and high blood pressure. However, because of the variety of presenting symptoms and features, it is a challenge to identify this condition, and patients are frequently misdiagnosed. The potentially critical course of aortic dissection can result in tragedy. We present the case of a 46-year-old woman who initially presented with a light headache and sensory loss in her right upper limb. She had a medical history of hypertension without regular medication, and her blood pressure (BP) was 110/67 mmHg on arrival. Four days later, she was sent to the emergency department again because she experienced transient loss of consciousness lasting for a few minutes. Her BP was 94/57 mmHg in the right arm and 89/54 in the left arm. She was admitted to the hospital, and the pulses in both upper limbs were impalpable on the following day. Chest magnetic resonance imaging (MRI) was arranged, and subsequently, aortic dissection was diagnosed. The case presented with unusual characteristics, which increased the difficulty in immediate correct diagnosis.

Functional magnetic resonance imaging evidence for activated functional brain areas following acupoint needling in the extremities

Totally three articles focusing on functional magnetic resonance imaging features of brain function in the activated brain regions of stroke patients undergoing acupuncture on the healthy limbs and healthy controls undergoing acupuncture on the lower extremities are published in three issues. We hope that our readers find these papers useful to their research.

Upper Extremities Injuries in Children Attending Pediatric Emergency Department-SFH, Riyadh-Saudi

Trauma is a physical injury caused by violence or other forces;in serious trauma, the patient will be at risk of death or loss of function. Trauma is a leading cause of morbidity and mortality among all age groups. Objective: To study the pattern and outcome of upper limbs trauma in children attending the pediatric emergency department. Methodology: This was a retrospective cross-sectional study conducted in the Department of Pediatrics at Security Forces Hospital-Al-Riyadh. Result: Total number of patients seen during the study period was 343 patients, their age range between 6 months and 13 years old with a mean age of 5.473 (±3.8572);also, results showed boys were 187 (54.5%) patients and girls were 156 (45.5%) patients. Based on the site of trauma in the upper limbs, lacerations were in 114 (33.2%), Hand and/or wrist fracture in 67 (19.5%), Nursemaid Elbow in 43 (12.5%), both Radius and Ulnar bones fracture in 33 (9.6%), Radius bone fracture in 29 (8.5%), supracondylar fracture in 22 (6.4%), Clavicle bone fracture in 20 (5.8%), Humorous bone fracture in 7 (2%), Condylar bone fracture 6 (1.7%), and there was 1 (0.3%) patient with Scapulae and Ulna fracture.

The Effects of Absorbable Materials in the Treatment for Non-Weight-Bearing Bone Fractures of Extremities

Objective:To study the effects of absorbable materials in non-weight-bearing bone fractures of extremities.Methods:After 66 patients with nonweight-bearing bone fractures of extremities were selected,absorbable materials were used in the observation group and metal materials were used in the control group.Results:After treatment,the bone healing in the observation group was significantly improved(P<0.05).Conclusion:the application of absorbable materials in non-weight-bearing bone fractures of extremities is effective.

Sensory reinnervation of free flaps in reconstruction of the breast and the upper and lower extremities

There is long-standing debate about sensate versus non-sensate free microvascular flaps among microsurgeons. The principle of connecting not only the vascular supply, but also sensitive nerves, in free tissue transfer is attractive. However, increased operating time and partial spontaneous innervation led to the common decision to restrict microsurgical tissue transfer to the vascular anastomosis and to leave the nerves ＂untreated＂. Nevertheless, in special cases such as breast reconstruction or extremity reconstruction, the question about sensory nerve coaptation of the flaps remains open. We present our experience with free microvascular tissue transfer for breast and extremity reconstruction and compare the data with previous literature and conclude that most free flap surgeries do not benefit from nerve coaptation.

Subcutaneous sarcoidosis of the upper and lower extremities: A case report and review of the literature

BACKGROUND Sarcoidosis is a granulomatous disease of unknown etiology that most often impacts the lungs.Cutaneous manifestations of sarcoidosis are seen among 9%- 37% of patients.Subcutaneous sarcoidosis is a rare presentation of cutaneous sarcoidosis with estimates of frequency ranging from 1.4%-16%.To date,very few articles and case reports have been written about this subject.In this paper,we describe a case of subcutaneous sarcoidosis and perform a review of the literature to determine if there are commonalities among patients who present with subcutaneous sarcoidosis.CASE SUMMARY A 38-year-old female,with a past medical history of arthritis and recurrent nephrolithiasis,presents with an 8-mo history of 4 firm,asymptomatic,skincolored nodules on her left and right upper extremities and neck.Needle biopsy and post-excisional pathology report both revealed well-formed,dense,noncaseating granulomas localized to the subcutaneous tissue.Chest computed tomography revealed mild mediastinal lymphadenopathy.A diagnosis of subcutaneous sarcoidosis was made,and the lesions were surgically removed.CONCLUSION Commonalities among patients presenting with subcutaneous sarcoidosis include: middle-aged female,lesions localizing to the upper or lower limbs,lymphadenopathy or pulmonary infiltration on chest imaging,elevated serum angiotensin-converting enzyme.

Magnetic resonance imaging of soft-tissue tumors of the extremities: A practical approach

Diagnosis of extremity soft-tissue tumors can be challenging.Characteristics of tumor margins can help precisely identify locally aggressive or non-aggressive behavior for surgical planning,but cannot differentiate benign from malignant lesions.Most malignant tumors can have inhomogeneous signals on T2-weighted images.Although a uniform signal on T2-weighted images can be a reliable indication of a benign lesion,a well-defined mass with homogeneous internal signal intensity does not definitively identify a benign lesion.Some common and distinctive soft-tissue lesions can have specific clinical and imaging features allowing a diagnosis without biopsy.These are known as determinate lesions.This illustrative report presents a diagnostic guide for extremity soft-tissue tumors based on tissue signal and morphological characteristics on magnetic resonance images.It is important for clinicians to be familiar with the imaging characteristics of common determinate lesions.

Update in combined musculoskeletal and vascular injuries of the extremities

Combined musculoskeletal and vascular injuries of the extremities are conditions in which a multidisciplinary approach is a sine qua non to ensure life initially and limb viability secondarily.Vascular injuries as part of musculoskeletal trauma are usually the result of the release of a high energy load in the wound site so that the prognosis is determined by the degree of soft-tissue damage,duration of limb ischemia,patient’s medical status and presence of associated injuries.The management of these injuries is challenging and requires a specific algorithm of action,because they are usually characterized by increased morbidity,amputation rate,infection,neurological and functional deficits,and they could be life threatening.Although vascular injuries are rare and occur either isolated or in the context of major combined musculoskeletal trauma,the high index of suspicion,imaging control,and timely referral of the patient to organized trauma centers ensure the best functional outcome of the extremity in such challenging cases.Even after a successful initial treatment of a combined trauma pattern,long-term follow-up is crucial to prevent and detect early possible complications.The purpose of this manuscript is to provide an update on diagnosis and treatment of combined musculoskeletal and vascular injuries of the extremities,from an orthopedic point of view.

Uncommon Tissue Defects of Upper Extremities: Bacillus Antracis

Introduction: Anthrax is a zoonotic disease caused by Bacillus anthracis spores. Cutaneous form is the most common and the least fatal form of the disease, however the disease is uncommon in Europe and U.S. and the reports in the literature are mostly case reports for upper extremity. Case Series: 7 patients, who were treated between 1999 and 2015 in our clinic with the diagnosis of cutaneous anthrax in their upper extremity, were included to our study. 3 patients applied directly to plastic surgery, others were consulted from the infectious disease clinics. Reconstructions were done with skin grafts or secondarily. Discussion: Anthrax causes cutaneous, gastrointestinal and inhalation forms of the disease. Despite being very rare in Europe and US, in Turkey there are many reported anthrax cases. However, cutaneous anthrax of upper extremity is reported rarely in the literature. Painless papule and vesicles are well defined as clinical findings. In anthrax, the excision of skin lesions or biopsies is contraindicated because of the risk of systemic spread. Conclusion: Despite cutaneous anthrax of the hand and upper extremity is very rare, the diagnosis is easy because of the typical presentation and history. Once the definitive diagnosis is set, the treatment is effortless with the antibiotherapy and first steps of the reconstruction ladder.

Clinical Effectiveness of the Plate Screw Internal Fixation Technique in the Treatment of Patients with Traumatic Fractures of Long Bones in the Lower Extremities

Objective: To investigate the effectiveness of the plate screw internal fixation technique on the clinical outcomes of patients with traumatic fractures of long bones in the lower extremities. Methods: From January 2022 to December 2023, 70 patients with traumatic fractures of long bones in the lower extremities were admitted to the hospital and randomly divided into two groups: the control group and the observation group, each consisting of 35 cases. The control group underwent traditional closed interlocking intramedullary nailing, while the observation group received internal fixation with steel plates and screws. Relevant surgical indicators, treatment effectiveness, and postoperative complication rates were compared between the two groups. Results: The observation group exhibited significantly short surgical duration (80.65 ± 5.01 vs. 88.36 ± 5.26 minutes), fracture healing time (13.27 ± 0.32 vs. 15.52 ± 0.48 weeks), and hospitalization days (10.49 ± 1.13 vs. 16.57 ± 1.15 days) compared to the control group (P = 0.000). The effective treatment rate was significantly higher in the observation group (29/82.86%) than in the control group (21/60.00%), with a significant difference observed (χ2 = 4.480, P = 0.034). Additionally, the complication rate in the observation group (2/5.71%) was significantly lower than that in the control group (8/22.86%), with a correlated difference (χ2 = 4.200, P = 0.040). Conclusion: The plate screw internal fixation technique demonstrates significant clinical efficacy in treating traumatic fractures of long bones in the lower extremities. It improves the healing rate, reduces complications, and represents a safe and effective treatment strategy worthy of widespread use and application.

结合机器学习的SA湍流模型闭合系数修正

将修正Morris分类筛选法与极端梯度提升(extreme gradient boosting,XGBoost)相结合,在计算流体动力学(computational fluid dynamics,CFD)数据驱动下,用于SA(Spalart-Allmaras)湍流模型闭合系数的修正.利用分类筛选法有效缩小闭合系数研究范围,同时依据XGBoost方法在小规模数据集下取得精度较高的拟合模型,有效提升系数修正效率.在三维DLR-F6-WB构型下进行了数值实验,实验结果显示利用本方法能够在三维复杂模型上基于小样本数据进行系数修正,修正后的升阻力系数计算精度得到了显著提升.

Competitive oxidation behavior of Ni-based superalloy GH4738 at extreme temperature

A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isothermal experiments. As a result of the competitive diffusion of alloying elements, the oxide scale included an outermost porous oxide layer (OOL), an inner relatively dense oxide layer (IOL), and an internal oxide zone (IOZ), depending on the temperature and time. A high temperature led to the formation of large voids at the IOL/IOZ interface. At 1200℃, the continuity of the Cr-rich oxide layer in the IOL was destroyed, and thus, spallation occurred. Extension of oxidation time contributed to the size of Al-rich oxide particles with the increase in the IOZ. Based on this finding,the oxidation kinetics of GH4738 was discussed, and the corresponding oxidation behavior at 900-1100℃ was predicted.

2023: Weather and Climate Extremes Hitting the Globe with Emerging Features

Globally,2023 was the warmest observed year on record since at least 1850 and,according to proxy evidence,possibly of the past 100000 years.As in recent years,the record warmth has again been accompanied with yet more extreme weather and climate events throughout the world.Here,we provide an overview of those of 2023,with details and key background causes to help build upon our understanding of the roles of internal climate variability and anthropogenic climate change.We also highlight emerging features associated with some of these extreme events.Hot extremes are occurring earlier in the year,and increasingly simultaneously in differing parts of the world(e.g.,the concurrent hot extremes in the Northern Hemisphere in July 2023).Intense cyclones are exacerbating precipitation extremes(e.g.,the North China flooding in July and the Libya flooding in September).Droughts in some regions(e.g.,California and the Horn of Africa)have transitioned into flood conditions.Climate extremes also show increasing interactions with ecosystems via wildfires(e.g.,those in Hawaii in August and in Canada from spring to autumn 2023)and sandstorms(e.g.,those in Mongolia in April 2023).Finally,we also consider the challenges to research that these emerging characteristics present for the strategy and practice of adaptation.