A stable liquid-solid interface of a lithium metal anode enabled by micro-region meshing.

Although lithium metal is regarded as the most promising anode for high energy density lithium ion batteries, the unstable solid-liquid interface during cycling severely shortens the battery lifetime. The Li deposition behavior is greatly influenced by the current density distribution on the surface of the electrode, which is significantly associated with the electrode structure. A well-designed electrode structure plays a key role in stabilizing the solid-liquid interface of the Li metal anode. In this work, a lithiophilic honeycomb-like Ni3N nanosheet array modified Ni foam (Ni3N@NF) is prepared to stabilize the lithium metal anode. The honeycomb-like Ni3N nanosheet arrays divide the surface of Ni foam into numerous micro-regions, enabling Li to independently deposit in each mesh. Besides, Li3N is generated resulting from the in situ reaction between Li and Ni3N, improving the transportation of Li-ions. Consequently, a symmetrical cell of Ni3N@NF-Li||Ni3N@NF-Li achieves stable Li plating/stripping behavior for over 1500 h at a current density of 1 mA cm-2. Besides, a full cell of Ni3N@NF-Li||LiFePO4 exhibits enhanced cycling stability and outstanding rate performance.

An amorphous hierarchical MnO2/acetylene black composite with boosted rate performance as an anode for lithium-ion batteries.

Amorphization is considered to be an effective way to enhance the electrochemical performances of electrode materials due to the existence of isotropy and numerous defects. Herein, an amorphous hierarchically structured MnO2/acetylene black (a-MnO2/AB) composite is successfully fabricated via a redox method and subsequent mechanical ball milling. The a-MnO2/AB composite is composed of approximately 300 nm flower-like amorphous MnO2 submicron spheres and acetylene black particles with a diameter of about 50 nm. The a-MnO2/AB electrode exhibits an initial coulombic efficiency of 73.2%, excellent rate capabilities of 318 mA h g-1 at 9.6 A g-1, and high specific capacity retention of 1300 mA h g-1 after 300 cycles at 1 A g-1. The amorphous structure can provide more channels for rapid lithium-ion transmission due to the disorder and defects, and the ion-diffusion coefficient (∼5 × 10-7 cm2 s-1) is higher than those of crystalline materials. Due to the strong interactions (Mn-O-C bonds) between MnO2 and AB as a result of the ball milling, the composite shows low charge transport resistance and small volume changes during the discharging/charging process. This work provides a facile route for the construction of amorphous hierarchically structured Mn-based oxides as anodes for lithium-ion batteries (LIBs).

Thermal Positioning Error Modeling of Servo Axis Based on Empirical Modeling Method.

In order to investigate the thermal effect of a servo axis' positioning error on the accuracy of machine tools, an empirical modeling method was proposed, which considers both the geometric and thermal positioning error. Through the analysis of the characteristics of the positioning error curves, the initial geometric positioning error was modeled with polynomial fitting, while the thermal positioning error was built with an empirical modeling method. Empirical modeling maps the relationship between the temperature points and thermal error directly, where the multi-collinearity among the temperature variables exists. Therefore, fuzzy clustering combined with principal component regression (PCR) is applied to the thermal error modeling. The PCR model can preserve information from raw variables and eliminate the effect of multi-collinearity on the error model to a certain degree. The advantages of this modeling method are its high-precision and strong robustness. Experiments were conducted on a three-axis machine tool. A criterion was also proposed to select the temperature-sensitivity points. The fitting accuracy of the comprehensive error modeling could reach about 89%, and the prediction accuracy could reach about 86%. The proposed modeling method was proven to be effective and accurate enough to predict the positioning error at any time during the machine tool operation.

Petal-like metal-organic framework stabilized Si@C with long cycle life and excellent kinetics.

Poor electrochemical kinetics caused by the unstable structure for the dramatically volumetric expansion (>300%) hinders the application of silicon in rechargeable lithium ion batteries. Si@C-Ni-MOF composites with petal-like Ni-MOFs as the skeleton and Si@C nanoparticles as the active center were synthesized via facile solvothermal process. The resulting Ni-MOF-Si@C material maintains admirable stability on cycling, and its capacity remains 1545.3 mAh g-1 with a high capacity retention rate of 99.79% after 300 cycles at the current density of 200 mA g-1. The enhancement on the kinetics is obtained, attributing to the porous structure created by the petal-like Ni-MOFs and the strong interface bonding between Si@C and Ni-MOFs.

A study on autonomous suturing task assignment in robot-assisted minimally invasive surgery.

BACKGROUND: Sutures are a set of standard actions which are accomplished by multi-instruments, researchers studied the robot autonomy of suturing, which was based on movement planning completed by a single instrument, but did not consider the assignment of suturing tasks to instruments. METHOD: A method was proposed for the autonomous suturing task assignment to instruments, which built a comprehensive evaluation index under some constraint conditions to determine the optimal scheme of the suturing task assignment to instruments. RESULTS: An experiment of duodenal ulcer repair with a suturing operation was conducted under the guidance of a surgeon, and the results showed that the optimal scheme of the suturing task assignment was obtained by using the proposed method. CONCLUSIONS: The proposed method can be used for autonomous suturing task assignment, which is beneficial for improving the intelligence of robot operation.

Ultra-Precision Machining of a Compound Sinusoidal Grid Surface Based on Slow Tool Servo.

Compound sinusoidal grid surface with nanometric finish plays a significant role in modern systems and precision calibrator, which can make the systems smaller, the system structure more simple, reduce the cost, and promote the performance of the systems, but it is difficult to design and fabricate by traditional methods. In this paper, a compound freeform surface constructed by a paraboloidal base surface and sinusoidal grid feature surface is designed and machined by slow tool servo (STS) assisted with single point diamond turning (SPDT). A novel combination of the constant angle and constant arc-length method is presented to optimize the cutting tool path. The machining error prediction model is analyzed for fabricating the compound sinusoidal grid surface. A compound sinusoidal grid surface with 0.03 mm amplitude and period of 4 is designed and cutting process is simulated by use of MATLAB software, machining experiment is done on ultra-precision machine tool, the surface profile and topography are measured by Taylor Hobson and Keyence VR-3200, respectively. After dealing with the measurement data of compound freeform surface, form accuracy 4.25 μm in Peak Village value (PV), and surface roughness 89 nm in Ra are obtained for the machined surface. From the theoretical analysis and experimental results, it can be seen that the proposed method is a reasonable choice for fabricating the compound sinusoidal grid surface.

Can Computed Tomography Accurately Measure Acetabular Anterversion in Developmental Dysplasia of the Hip? Verification and Characterization Using 3D Printing Technology.

BACKGROUND: One of the important pathologic changes in developmental dysplasia of the hip (DDH) is increased acetabular version angle (AA). Reasonable correction for excessive AA is an important step in the treatment of DDH, making accurate AA measurement very crucial. However, the results of different AA measurement methods vary. Thus, this study aimed to compare the difference in AA measurements between 2-dimensional computed tomography (2D-CT) and 3-dimensional computed tomography (3D-CT) in children with DDH and to identify the AA degree in children with DDH to guide treatment. METHODS: AA was measured by 2D-CT and 3D-CT in 186 children with DDH, and the measurement results were compared with the physical measurement result in the 3D-printed pelvis (3D-PP) model. The 3D-PP was a 1:1 model identical to the human pelvis. All patients were unilaterally affected. RESULTS: The results of AA measurement through 2D-CT, 3D-CT, and 3D-PP of normal hips were 14.0±6.6, 11.9±5.3, and 11.9±3.4 degrees, respectively, whereas those of the dislocated hips were 24.9±8.9, 19.8±5.2, and 19.5±4.3 degrees, respectively. In both the normal and dislocated hip groups, the results between 2D-CT and 3D-CT was significantly different (P<0.05), but there was no difference between the results of 3D-CT and 3D-PP (P>0.05). The AA of the normal and dislocated hips as measured by 3D-PP was 11.9±3.6 and 19.6±4.3 degrees, respectively, with statistically significant difference (P<0.05). In the dislocated hips, a significant positive correlation was found between age and AA (r=0.756, P<0.05) and between AA and degree of dislocation (r=0.837, P<0.05). CONCLUSIONS: 3D-CT is more accurate than 2D-CT for AA measurement, and compared with normal hips, AA in dislocated hips increased by ∼7.7 degrees on average. AA increases as age and degree of dislocation increase. LEVEL OF EVIDENCE: Level II.

Study about Mechanical Property and Machinability of Polyimide.

Polyimide (PI) is a kind of polymer material with properties of high heat-resistance and good mechanical strength. As a special engineering material, it has been widely used in the fields of aviation, nanotechnology, etc. PI has been regarded as one of the most promising engineering plastics in the future. Therefore, further research must be made on its mechanical properties and machinability of the PI, especially in ultra-precision machining. In this paper, both of the mechanical properties and machinability have been studied respectively. Through the nanoindentation experiment, the nanoindentation hardness and elastic modulus of PI are analyzed. Also, the single point diamond turning (SPDT) experiment is conducted to show that the form accuracy and surface roughness of PI surface can reach a submicron degree in peak-to-valley (PV) and a nanometer scale in surface roughness (Ra) respectively. The results demonstrate that the PI possesses good mechanical properties and machinability.

Dynamic long leg casting fixation for treating 12- to 18-month-old infants with developmental dysplasia of the hip.

Objective To evaluate the effect of dynamic long leg casting in paediatric patients with developmental dysplasia of hip (DDH) diagnosed at 12-18 months. Methods The adductor tenotomy, closed reduction, and dynamic long leg casting method was adopted to treat paediatric patients with DDH. The hips were divided into four groups according to the Tonnis radiographic dislocation classification. Groups were also classified according to the baseline acetabular index (AI): 30°-35°, 36°-40°, and > 40°. The outcomes of the reductions were evaluated according to McKay's hip function criteria and Severin's radiological criteria. Results A total of 246 patients (339 hips) had complete follow-up data. After 3 months of orthosis fixation, the results were satisfactory in 264 hips (77.88%). Hip function was rated as 'excellent' or 'good' in 43 of 51 (84.31%) Tonnis type 1 hips, 125 of 155 (80.65%) type 2 hips, 70 of 90 (77.78%) type 3 hips, and 34 of 43 (79.07%) type 4 hips. The higher the baseline AI, the lower the rates of 'excellent' and 'good' hip function. Favourable radiological results (Severin types I and II) were found in 266 of 339 (78.47) hips. Conclusions Dynamic long leg casting is an effective method for treating patients with DDH aged 12-18 months at diagnosis.

Comparison and Analysis on Mechanical Property and Machinability about Polyetheretherketone and Carbon-Fibers Reinforced Polyetheretherketone.

The aim of this paper is to compare the mechanical property and machinability of Polyetheretherketone (PEEK) and 30 wt% carbon-fibers reinforced Polyetheretherketone (PEEK CF 30). The method of nano-indentation is used to investigate the microscopic mechanical property. The evolution of load with displacement, Young's modulus curves and hardness curves are analyzed. The results illustrate that the load-displacement curves of PEEK present better uniformity, and the variation of Young's modulus and hardness of PEEK both change smaller at the experimental depth. The machinability between PEEK and PEEK CF 30 are also compared by the method of single-point diamond turning (SPDT), and the peak-to-valley value (PV) and surface roughness (Ra) are obtained to evaluate machinability of the materials after machining. The machining results show that PEEK has smaller PV and Ra, which means PEEK has superior machinability.

Evaluation of femoral head coverage following Chiari pelvic osteotomy in adolescents by three-dimensional computed tomography and conventional radiography.

INTRODUCTION: Currently, the cover of the femoral head was mainly assessed using conventional plain films after Chiari pelvic osteotomy in most studies. The purpose of the current study was to observe whether the femoral head coverage measured by three-dimensional computed tomography (3D-CT) was consistent with the radiographic findings. PATIENTS AND METHODS: A total of 24 patients (24 hips) with an average age of 11.5 years, underwent Chiari osteotomy due to acetabular dysplasia, and 15 subjects (30 hips) of normal control with a mean age of 12 years were involved in the study. The pre- and postoperative coverage of femoral head was measured by using conventional plain film and 3D-CT on the anterior 1/4, middle 1/2, and posterior 1/4 coronal plane. The anterolateral, mediolateral and posterolateral coverage measured by 3D-CT were compared with the coverage measured by plain radiograph, and which were also compared with the normal control individuals. RESULTS: The postoperative anterolateral, mediolateral coverage measured by 3D-CT was significantly smaller than that measured by radiography (P < 0.01). No significant difference was found between the 3D-CT measurements on the posterolateral coverage and the radiographic results. The anterolateral femoral head coverage in the patients following Chiari pelvic osteotomy was also smaller than that in the normal control individuals (P = 0.026). In contrast, the postoperative posterolateral coverage in the patients was more excessive than that in the normal control individuals (P = 0.001). CONCLUSION: Conventional radiographs may show sufficient cover of the femoral head after Chiari osteotomy, whereas in fact, the cover may be not perfect, especially on the anterolateral part. Therefore, the postoperative 3D-CT is beneficial for evaluating the outcome of Chiari osteotomy, especially when the anterolateral coverage o

Evaluation of the modified Albee arthroplasty for femoral head loss secondary to septic arthritis in young children: surgical technique.

BACKGROUND: Surgical treatment options for femoral head deficiency in infants secondary to septic arthritis of the hip are varied and associated with uncertain long-term outcomes. The modified Albee arthroplasty has been considered an acceptable procedure; however, the long-term outcomes of this procedure have not been reported, to our knowledge. We evaluated the long-term outcomes of the modified Albee arthroplasty in young patients with severe sequelae of septic arthritis of the hip. METHODS: We retrospectively studied twenty-one children (twenty-one hips) in whom Choi type-IVB sequelae of septic arthritis of the hip had been treated with a modified Albee arthroplasty and six patients with the same sequelae who had been managed with simple observation. The Trendelenburg sign, pain, the range of motion, hip function, the Harris hip score, and limb-length discrepancy were assessed clinically. Remodeling of the femoral head, hip stability, and arthritic changes in the hip were evaluated radiographically. RESULTS: The twenty-one patients with the modified Albee arthroplasty were followed for an average of 121.2 ± 38.6 months and had better outcomes, in terms of the Trendelenburg sign, the Harris hip score, pain, the hip range of motion, and limb-length discrepancy, than the six patients who underwent simple observation. Patients who were two years of age or younger at the time of the arthroplasty exhibited a significantly less severe limb-length discrepancy and less loss of motion than those who were older than two at the time of the surgery. Furthermore, limb-length discrepancy was positively correlated and the range of motion of the hip and the Harris hip scores were negatively correlated with the patient's age at the time of the surgery, suggesting that early surgery in patients with severe sequelae of septic arthritis of the hip is associated with a better clinical outcome. CONCLUSIONS: The modified Albee arthroplasty is a feasible and clinically useful procedure for the treatment of severe sequelae of septic arthritis of the hip, particularly in children who are two years of age or younger.

Psoas abscess with associated septic arthritis of the hip in infants.

We describe psoas abscess with concomitant septic hip arthritis in 2 infants, 3 and 7 months old. The common clinical features were a palpable mass in the inguinal region, irritable hip, and delayed treatment. The diagnosis of septic hip was delayed in one child, and they both had residual hip deformity at follow-up. It is possible that initial delay in diagnoses resulted in the concurrent pathologic condition because of spread of infection. These 2 cases demonstrate the first known reports of concurrent psoas abscess and septic hip arthritis in infancy. Magnetic resonance imaging is a valuable method to identify these concurrent pathologic conditions. A proposed etiologic mechanism is also discussed in the article.

[Evaluation of mid-term follow-up after Salter innominate osteotomy in developmental dysplasia of the hip].

OBJECTIVES: To evaluate the mid-term outcome after Salter innominate osteotomy in developmental dysplasia of the hip (DDH), and to observe the developmental characteristics of the hip after operation and the relationships between the mid-term outcome and radiographic parameters as well as age at operation. METHODS: : Forty-four patients with 61 treated hips were selected. The patients were treated with Salter innominate osteotomy and followed-up for at least three years with intact serial radiographs. Radiographs taken before operation, 6 weeks, 1 year and 2 - 3 years after operation and in the latest follow-up were selected. Acetabular index (AI), Sharp acetabular angle (SAA) and center-edge angle of Wiberg (CEA) were measured and Severin classification was done according to radiographs taken in the latest follow-up. RESULTS: The average correction of AI was 14° postoperatively. The acetabulum remodels best at 2-3 years after operation when the average AI became very close to normal. In the latest follow-up the SAA was 41° which could be regarded as normal. Postoperative CEA was on average 23° which increased to 25° 2-3 years later. In the latest follow-up, the average CEA was 26°. The ratio of excellent and good outcomes (Severin I, II) was 84%, while the ratio of moderate and poor outcomes (Severin III, IV, V, VI) was 16%. Age at operation had a negative effect on outcomes. Although 70% patients operated after age 6 had satisfactory outcomes. The Severin I, II group showed no difference in AI from III, IV, V, VI group 6 weeks after operation, but the AI of the former obviously improved 2-3 years after operation while that of the latter deteriorated. Significant difference in SAA and the CEA could be observed in the latest follow-up. CONCLUSIONS: Salter innominate osteotomy focuses on normalizing the abnormal acetabular direction in DDH children as well as stimulating the remodeling of the acetabulum, which provides a satisfactory middle-term outcome. The acetabulum remodels rapidly during the first three years after operation when AI and CEA develops into normal. Interference should be adopted if these changes have not appeared in the first three years.

Evaluation of the modified Albee arthroplasty for femoral head loss secondary to septic arthritis in young children.

BACKGROUND: Surgical treatment options for femoral head deficiency in infants secondary to septic arthritis of the hip are varied and associated with uncertain long-term outcomes. The modified Albee arthroplasty has been considered an acceptable procedure; however, the long-term outcomes of this procedure have not been reported, to our knowledge. We evaluated the long-term outcomes of the modified Albee arthroplasty in young patients with severe sequelae of septic arthritis of the hip. METHODS: We retrospectively studied twenty-one children (twenty-one hips) in whom Choi type-IVB sequelae of septic arthritis of the hip had been treated with a modified Albee arthroplasty and six patients with the same sequelae who had been managed with simple observation. The Trendelenburg sign, pain, the range of motion, hip function, the Harris hip score, and limb-length discrepancy were assessed clinically. Remodeling of the femoral head, hip stability, and arthritic changes in the hip were evaluated radiographically. RESULTS: The twenty-one patients with the modified Albee arthroplasty were followed for an average of 121.2 +/- 38.6 months and had better outcomes, in terms of the Trendelenburg sign, the Harris hip score, pain, the hip range of motion, and limb-length discrepancy, than the six patients who underwent simple observation. Patients who were two years of age or younger at the time of the arthroplasty exhibited a significantly less severe limb-length discrepancy and less loss of motion than those who were older than two at the time of the surgery. Furthermore, limb-length discrepancy was positively correlated and the range of motion of the hip and the Harris hip scores were negatively correlated with the patient's age at the time of the surgery, suggesting that early surgery in patients with severe sequelae of septic arthritis of the hip is associated with a better clinical outcome. CONCLUSIONS: The modified Albee arthroplasty is a feasible and clinically useful procedure for the treatment of severe sequelae of septic arthritis of the hip, particularly in children who are two years of age or younger.

The mechanism of acute elbow flexion contracture in children with congenital proximal radioulnar synostosis.

We have evaluated and treated 3 cases of acute onset elbow flexion contracture in children ranging in age from 6 to 13 years, with type-IV (Cleary and Omer) congenital proximal radioulnar synostosis. All were resolved by manipulative traction under general anesthesia during which an audible elbow "snap" was noted. Two of the cases required surgical treatment of a deformed radial head with good results after a 2 to 4-year follow-up. Our clinical radiographic and intraoperative evidence suggests that the acute onset fixed-flexion contracture results from an anterosuperiorly overgrown dislocated radial head becoming trapped under hypertrophied annular ligament-type tissue after elbow hyperflexion. Excision of the dislocated radial head after release from its entrapment was effective in 2 of the 3 patients in this report, and should be considered.

The split-heel technique in the management of chronic calcaneal osteomyelitis in children.

The split-heel technique has distinct advantages over the conventional medial or lateral approach in the operative debridement of extensive and predominantly plantar chronic calcaneal osteomyelitis in children above 5 years of age. We report three cases (age 5.5-11 years old) of chronic calcaneal osteomyelitis in children treated using the split-heel approach with 3-10 years follow-up showing excellent functional and cosmetic results.

[Association study between mutations of transcription regulator sequences of COL1A1 gene and idiopathic con-genital talipes equinovarus].

RT-PCR was used to detect the expressions of COL1A1 mRNA in 20 patients with idiopathic congenital talipes equinovarus (ICTEV). The primers were designed by Primer 5 according to sequences of -1 031 bp~ +30 bp and the first intron of COL1A1. PCR-DGGE was used to screen the mutations in COL1A1 gene. Expression of COL1A1 on mRNA levels showed significantly higher in patients with ICTEV than in normal persons (t=12.680, P < 0.05). By DNA sequencing, a -161(T--> C) heterozygous mutation and a+ 274(C-->G) homozygous mutation were detected, and both were new identified mutations. These results indicated that the mutations in transcription regulator sequences of COL1A1 could cause ICTEV.

[Proteomic analysis of the ankle joint bone, ankle joint tissue and spinal cord of clubfoot-like deformity in rat fetuses].

OBJECTIVE: To explore the etiology of idiopathic talipes equinovarus (ITEV) in all-trans retinoic acid (ATRA) induced clubfoot-like deformity in rat fetuses with two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). METHODS: Clubfoot-like deformity model in rat fetuses was induced with ATRA (135 mg/kg) in gestation day (GD10) pregnant Wistar rats. 2-DE was applied to separate the total proteins of ankle joint tissue, ankle joint bone and spinal cord of the animal models. The Coomassie Brilliant Blue staining gels were analyzed by 2-DE software PDQuest 7.1.0. Selected differential protein spots were identified with peptide mass fingerprinting based on matrix-assisted laser adsorption/ionization time-of-flight mass spectrometry and database searching. xiap, tnnt1 and col2 alpha 1, three genes of the differential proteins, were identified furthermore. Apoptosis study was made in terminal deoxynucleotidyl transferase nick end labeling. RESULTS: There were many differential expressed proteins in the clubfoot-like deformity model. Out of the differentially expressed proteins,16 protein spots were identified to be differentially expressed in the clubfoot-like deformity model with MS. Three of the 16 protein spots, xiap, tnnt1 and col2 alpha 1 were confirmed to be significantly down-regulated by the RT-PCR, and Xiap was further confirmed to be significantly down-regulated with immunohistochemistry. Another randomly selected gene, ngfr, did not express differently in ATRA-induced clubfoot-like deformity in rat fetuses. The rates of the apoptosis in the spinal, bone of the clubfoot-like deformity fetuses was 5.4 and 10 times of those of the normal fetuses respectively. CONCLUSION: The results suggest that there are certain differently expressed proteins in ankle joint tissue, ankle joint bone and spinal cord of the ATRA-induced clubfoot-like deformity in rat fetuses, and Xiap, sTnT, and Col2 alpha 1 show a significant correlation with ITEV. Ngfr is not correlation with ITEV. Apoptosis plays a key role in the development of ITEV and related to the decreased expression of the Xiap.

[Association and mutation analysis of GLI3 gene in idiopathic congenital talipes equinovarus].

OBJECTIVE: To explore the association and mutation of GLI3 gene in idiopathic congenital talipes equinovarus(ICTEV). METHODS: (1) Genotype of 2 single nucleotide polymorphism (SNP) in 84 idiopathic congenital talipes equinovarus nuclear pedigree were analyzed by restriction fragment length polymorphism. Association analysis was directed between single SNP locus and ICTEV through ETDT software, respectively.(2) Mutation sites in exon 9,10,11,12 of GLI3 gene were detected in 103 patients with ICTEV by denaturing gradient gel electrophoresis technique. RESULTS: rs929387ls located in exon 14 of GLI3 gene have transmission disequilibrium in 84 nuclear pedigrees (P<0.05), and rs846266 located in exon 4 have no transmission disequilibrium (P>0.05). A synonymous mutation in exon 9 was detected in one patient and his mother. CONCLUSION: There is an association between GLI3 gene and ICTEV, and exons 9,10,11,12 are not its mutation hot spots.