Nano-cutting mechanism of ion implantation-modified SiC: reducing subsurface damage expansion and abrasive wear.

This study utilized ion implantation to modify the material properties of silicon carbide (SiC) to mitigate subsurface damage during SiC machining. The paper analyzed the mechanism of hydrogen ion implantation on the machining performance of SiC at the atomic scale. A molecular dynamics model of nanoscale cutting of an ion-implanted SiC workpiece using a non-rigid regular tetrakaidecahedral diamond abrasive grain was established. The study investigated the effects of ion implantation on crystal structure phase transformation, dislocation nucleation, and defect structure evolution. Results showed ion implantation modification decreased the extension depth of amorphous structures in the subsurface layer, thereby enhancing the surface and subsurface integrity of the SiC workpiece. Additionally, dislocation extension length and volume within the lattice structure were lower in the ion-implanted workpiece compared to non-implanted ones. Phase transformation, compressive pressure, and cutting stress of the lattice in the shear region per unit volume were lower in the ion-implanted workpiece than the non-implanted one. Taking the diamond abrasive grain as the research subject, the mechanism of grain wear under ion implantation was explored. Grain expansion, compression, and atomic volumetric strain wear rate were higher in the non-implanted workpiece versus implanted ones. Under shear extrusion of the SiC workpiece, dangling bonds of atoms in the diamond grain were unstable, resulting in graphitization of the diamond structure at elevated temperatures. This study established a solid theoretical and practical foundation for realizing non-destructive machining at the atomic scale, encompassing both theoretical principles and practical applications.

A comparison between transforaminal lumbar epidural injection performed under picture archiving and communication systems-based magnetic resonance imaging planning and injection under immediate X-ray guidance.

OBJECTIVES: The study aimed to compare the treatment cost, operation time, clinical effect, and complications between punctures done under magnetic resonance imaging (MRI) planning based on picture archiving and communication systems (PACS) and punctures done under immediate X-ray fluoroscopy guidance in the treatment of lumbar disc herniation by transforaminal lumbar epidural injection. PATIENTS AND METHODS: In this prospective study conducted between October 2016 and June 2021, 128 patients were randomly divided into Groups A and B by the random number table method. In Group A (n=66; 36 males, 30 females; mean age: 64.5±2.4 years, range, 50 to 72 years), puncture was performed by planning with PACS-based MRI; in Group B (n=62; 34 males, 28 females; mean age: 65.3±2.6 years; range, 48 to 73 years), puncture was performed under immediate X-ray guidance. The cost of treatment, duration of procedure, clinical outcome, and complications were compared between the two groups. RESULTS: The difference in treatment cost in Groups A and B was statistically significant (p<0.001), with 755.67±29.45 yuan and 1.158.08±43.92 yuan, respectively. The mean treatment time was statistically significant (p<0.001) between the groups, with 21.16±1.91 min in Group A and 37.26±2 min in Group B. However, there was no significant difference between Group A and Group B in terms of improvement in pain scores and Oswestry disability index (both p>0.05). There was also no significant difference between Group A and Group B in terms of complication rates (both p>0.05). CONCLUSION: Compared to immediate X-ray guided puncture, the puncture method using PACS for MRI planning shortened the transforaminal lumbar epidural injection procedure time and reduced the treatment costs without exposing the physician or patient to additional radiation, while there was no significant difference in the short-term clinical outcome or complication rate.

Fabrication of the high-precision micro-structure array using a phase shift modulation of superimposed oscillation in ultra-precision grinding.

Various micro-structure surface texturing methods have been used to produce optical functional surface in the grinding, such as the textured grinding wheel, wheel path control and off-spindle-axis grinding. However, those grinding technologies are inherently challenged to employ in large-scale surface grinding due to the extremely high requirement for wheel cutting profile dressing. In this study, a novel phase shift modulation based on wheel oscillation motion was proposed to generate the micro-structure array in ultra-precision grinding. The phase shift effect involved in the surface micro-structure generation is investigated, in which the role of the second phase shift on superimposed mode and micro-waviness forms is discussed. A theoretical model based on the tool superimposed oscillation is established to study the micro-structure texture generation mechanism by considering the second phase shift. The influence of modulation frequency in the case of phase shift and out of phase shift on the surface texture generation both for the striation pattern and micro-structure is compared to clarify the transition between the continuous grooves and the discrete micro-structure array. The study indicates that the phase shift modulation represents a novel paradigm for fabricating micro-structure array with considerable capability and high efficiency in ultra-precision grinding.

Streptococcus gordonii finger infection: Case report and a review of the literature.

RATIONALE: Streptococcus gordonii is a rare cause of finger suppurative infection. Very few cases have been reported of its treatment. PATIENT CONCERNS: A 68-year-old male of severe finger infection. Bacterial culture of synovial fluid revealed S gordonii.According to the patient's history and auxiliary examination, the patient was diagnosed with S gordonii infection. Here, we review the diagnosis and treatment of this patient and describe the clinical and epidemiological characteristics of the patient. DIAGNOSES: Streptococcus gordonii finger infection.Interventions: In the case of ineffective oral antibiotics, this patient chose to pursue an abscess incision, but in the course of treatment,the flexor digitorum tendon dissolved and eventually ruptured. OUTCOMES: The infection was controlled after intravenous injection of vancomycin. The incision was sutured 2 weeks later. No recurrence of infection was found after 3 months of follow-up. LESSONS: The treatment included antibacterial and abscess treatments. In the absence of drug sensitivity results, antibiotics can be used empirically. If empirical anti-microbial treatment fails, the antibiotic regimen should be changed in a timely manner, Vancomycin may be an antibiotic choice.

Precision micro-milling process: state of the art.

Micro-milling is a precision manufacturing process with broad applications across the biomedical, electronics, aerospace, and aeronautical industries owing to its versatility, capability, economy, and efficiency in a wide range of materials. In particular, the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain, as well as for rapid micro-texturing and micro-patterning, which will have great importance in the near future in bio-implant manufacturing. This is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant industries. However, inherent physical process constraints of machining arise as macro-milling is scaled down to the microdomain. This leads to some physical phenomena during micro-milling such as chip formation, size effect, and process instabilities. These dynamic physical process phenomena are introduced and discussed in detail. It is important to remember that these phenomena have multifactor effects during micro-milling, which must be taken into consideration to maximize the performance of the process. The most recent research on the micro-milling process inputs is discussed in detail from a process output perspective to determine how the process as a whole can be improved. Additionally, newly developed processes that combine conventional micro-milling with other technologies, which have great prospects in reducing the issues related to the physical process phenomena, are also introduced. Finally, the major applications of this versatile precision machining process are discussed with important insights into how the application range may be further broadened.

Performance Analysis of Surface Reconstruction Algorithms in Vertical Scanning Interferometry Based on Coherence Envelope Detection.

Optical interferometry plays an important role in the topographical surface measurement and characterization in precision/ultra-precision manufacturing. An appropriate surface reconstruction algorithm is essential in obtaining accurate topography information from the digitized interferograms. However, the performance of a surface reconstruction algorithm in interferometric measurements is influenced by environmental disturbances and system noise. This paper presents a comparative analysis of three algorithms commonly used for coherence envelope detection in vertical scanning interferometry, including the centroid method, fast Fourier transform (FFT), and Hilbert transform (HT). Numerical analysis and experimental studies were carried out to evaluate the performance of different envelope detection algorithms in terms of measurement accuracy, speed, and noise resistance. Step height standards were measured using a developed interferometer and the step profiles were reconstructed by different algorithms. The results show that the centroid method has a higher measurement speed than the FFT and HT methods, but it can only provide acceptable measurement accuracy at a low noise level. The FFT and HT methods outperform the centroid method in terms of noise immunity and measurement accuracy. Even if the FFT and HT methods provide similar measurement accuracy, the HT method has a superior measurement speed compared to the FFT method.

Pseudotear Sign of the Anterior Horn of the Meniscus.

PURPOSE: To observe the morphology of the transverse geniculate ligament of the knee (TGL) by magnetic resonance imaging (MRI) and to analyze the cause of the pseudotear sign of the anterior horn of the meniscus caused by the TGL. METHODS: Patients who underwent MRI examination of the knee joint in the orthopaedics department of our hospital from July 2016 to August 2019 were identified. The occurrence rate, length, width, thickness, cross-sectional shape, pattern, appearance, and position relative to the anterior horn of the lateral and medial meniscus and anatomical variations were observed by multiplane and multisequence MRI. The frequency and cause of the pseudotear sign also were observed. RESULTS: The data of 101 patients were analyzed. Among them, 60 were male, and 41 were female. The average age was 42.01 (18-75) years. The occurrence rate of the TGL was 67.3% (68/101), the average length was 38.75 ± 3.56 mm, the median coronal diameter was 1.79 ± 0.60 mm, the median sagittal diameter was 1.88 ± 0.35 mm, and the cross-sectional morphology was mostly oval and round. There were 5 types of TGL connection to the anterior horn of the medial meniscus: type 1, located at the front edge; type 2, located at the upper front edge; type 3, located at the upper edge; type 4, located at the back upper edge; and type 5, was located at the back edge of the anterior horn of the medial meniscus. There was only one type of TGL insertion into the anterior horn of the lateral meniscus, located at the anterior superior edge of the anterior horn of the lateral meniscus. There were 4 cases of the pseudotear sign in the anterior horn of the meniscus, 3 in the lateral meniscus and 1 in the medial meniscus. The pseudotear sign of the anterior horn of the meniscus caused by the TGL was observed at a rate of 5.88% (4/68). CONCLUSIONS: In MRI examination of the knee, the anterior horn of the meniscus sometimes shows a pseudotear sign. According to the shape and route of the TGL on MRI and the direction and position of the pseudotear sign of the anterior horn of the meniscus, true and false tears of the anterior horn of the meniscus can be identified. LEVEL OF EVIDENCE: Level III, diagnostic study (retrospective, noncomparative, observational case series without a consistently applied reference "gold" standard).

Biometric Measurement of Anterior Segment: A Review.

Biometric measurement of the anterior segment is of great importance for the ophthalmology, human eye modeling, contact lens fitting, intraocular lens design, etc. This paper serves as a comprehensive review on the historical development and basic principles of the technologies for measuring the geometric profiles of the anterior segment. Both the advantages and drawbacks of the current technologies are illustrated. For in vivo measurement of the anterior segment, there are two main challenges that need to be addressed to achieve high speed, fine resolution, and large range imaging. One is the motion artefacts caused by the inevitable and random human eye movement. The other is the serious multiple scattering effects in intraocular turbid media. The future research perspectives are also outlined in this paper.

PLA2G10 facilitates the cell-cycle progression of soft tissue leiomyosarcoma cells at least by elevating cyclin E1/CDK2 expression.

Soft tissue leiomyosarcoma (STLMS) is a major histological subtype of adult sarcoma. Although the molecular mechanisms ofLMS have been gradually revealed, no valid therapeutic targets have been identified. In this study, we performed a systematic screening to explore relapse-associated genes in STLMS, using data from The Cancer Genome Atlas-Sarcoma (TCGA-SARC). Then, we investigated the functional role of the gene with the best relapse-prediction value in STLMS by both in-vitro and in-vivo studies. Results showed that AMH and PLA2G10 were two genes with area under curve (AUC) values higher than 0.80 in ROC analysis when detecting relapse. Patients in the high AMH or PLA2G10 expression group had significantly worse relapse-free survival (RFS) compared to the respective low expression group. PLA2G10 was highly expressed in STLMS, but not in other sarcoma subtypes. PLA2G10 overexpression promoted SK-LMS-1 cell growth and G1/S transition, while PLA2G10 knockdown slowed the growth and resulted in G1 phase arrest. PLA2G10 overexpression markedly increased the expression of CDK2 and cyclin E1, but did not influence CDK4, CDK6, cyclin D1, CDK1 or cyclin A expression. PLA2G10 overexpression enhanced SK-LMS-1 cell-derived xenograft tumor growth in nude mice, while PLA2G10 inhibition slowed the growth. Mutation of two critical catalyzing amino acid residues (p.H88A and p.D89A) abrogated the capability of PLA2G10 to catalyze the production of arachidonic acid (AA), and also canceled the regulatory effects on cyclin E1 and CDK2 expression, as well as G1/S transition. In conclusion, PLA2G10 was a specific relapse-associated gene in STLMS. It facilitated the cell-cycle progression of STLMS cells at least by elevating the expression of cyclin E1 and CDK2. The hydrolytic activity was crucial for its oncogenic properties.