[Research on Locating Device for the Entry Point of Intramedullary Nail Based on Inertial Navigation].

Objective: To introduce a locating device for the entry point of intramedullary nail based on the inertial navigation technology, which utilizes multi-dimensional angle information to assist in rapid and accurate positioning of the ideal direction of femoral anterograde intramedullary nails' entry point, and to verify its clinical value through clinical tests. Methods: After matching the locating module with the developing board, which are the two components of the locating device, they were placed on the skin surface of the proximal femur of the affected side. Anteroposterior fluoroscopy was performed. The developing angle corresponding to the ideal direction of entry point was selected based on the X-ray image, and then the yaw angle of the locating module was reset to zero. After resetting, the locating module was combined with the surgical instrument to guide the insertion angle of the guide wire. The ideal direction of entry point was accurately located based on the angle guidance. By setting up an experimental group and a control group for clinical surgical operations, the number of guide wire insertion times, surgical time, fluoroscopy frequency, and intraoperative blood loss with or without the locating device was recorded. Results: Compared to the control group, the experimental group showed significant improvement in the number of guide wire insertion times, surgical time, fluoroscopy frequency, and intraoperative blood loss, with a statistically significant difference (P<0.01). Conclusion: The locating device can assist doctors in quickly locating the entry point of intramedullary nail, effectively reducing the fluoroscopy frequency and surgical time by improving the success rate of the guide wire insertion with one shot, improving surgical efficiency, and possessing certain clinical value.

Unveiling orientation dependence of anisotropic plasticity in polycrystalline copper by nanoindentation.

The mechanical properties of crystalline materials are influenced by their deformation behavior, which is associated with their microstructural characteristics. Specifically, crystallographic orientation greatly affects the microscale plastic deformation of individual grains. In this study, experiments and finite element simulations of Berkovich nanoindentations are conducted to investigate the impact of crystallographic orientation in polycrystalline copper. A crystal plasticity constitutive model is developed for copper materials, which accurately captures their indentation mechanical response. The results showed that the indentation behavior of polycrystalline copper exhibits a high degree of anisotropy due to significant variation in slip systems for different crystallographic orientations. This results in different mechanical responses of individual grains and distinct material pileup morphologies on the indented surface. Additionally, the study revealed that crystallographic orientation plays a critical role in determining the indentation size effect. These findings have important implications for the design of materials where plasticity is a crucial factor.

Pollutant Degrading Enzyme: Catalytic Mechanisms and Their Expanded Applications.

The treatment of environmental pollution by microorganisms and their enzymes is an innovative and socially acceptable alternative to traditional remediation approaches. Microbial biodegradation is often characterized with high efficiency as this process is catalyzed via degrading enzymes. Various naturally isolated microorganisms were demonstrated to have considerable ability to mitigate many environmental pollutants without external intervention. However, only a small fraction of these strains are studied in detail to reveal the mechanisms at the enzyme level, which strictly limited the enhancement of the degradation efficiency. Accordingly, this review will comprehensively summarize the function of various degrading enzymes with an emphasis on catalytic mechanisms. We also inspect the expanded applications of these pollutant-degrading enzymes in industrial processes. An in-depth understanding of the catalytic mechanism of enzymes will be beneficial for exploring and exploiting more degrading enzyme resources and thus ameliorate concerns associated with the ineffective biodegradation of recalcitrant and xenobiotic contaminants with the help of gene-editing technology and synthetic biology.

Digital virtual reduction combined with individualized guide plate of lateral tibial condyle osteotomy for the treatment of tibial plateau fracture.

BACKGROUND: Current treatments do not support direct exposure of fracture fragments, resulting in the inability to directly observe the articular surface during surgery for accurate reduction and firm fixation. OBJECTIVE: The aim of the study was to explore the treatment effect of digital virtual reduction combined with individualized guide plate of lateral tibial condyle osteotomy on tibial plateau fracture involving the lateral posterior condyle collapse. METHODS: 41 patients with tibial plateau fracture involving the lateral posterior condyle collapse were recruited in the trial. All patients underwent Computed Tomography (CT) scanning before operation. After operation, fracture reduction was evaluated using Rasmussen score and function of knee joint was assessed using hospital for special surgery (HSS) score. RESULTS: 41 patients were followed-up 6-26 months (mean, 15.2 months). Fracture reduction was good after operation, with an average of 13.3 weeks of fracture healing without serious complications. The excellent and good rate was 97.6%. The joint movement degree was -5∘∼0∘∼135∘ with an average of 125.5∘. CONCLUSIONS: Digital virtual reduction combined with individualized guide plate of lateral tibial condyle osteotomy was effectively for treating tibial plateau fracture involving the lateral posterior condyle collapse.

Utilization of cannulated screw fixation of Jail and TiRobot-assisted percutaneous indirect reduction technique for AO/OTA type 41B2 tibial plateau fracture treatment.

PURPOSE: The present study was designed to investigate the precise procedure and effectiveness of percutaneous minimally invasive fixation assisted by TiRobot in managing AO/OTA type 41B2 tibial plateau fracture to provide an alternative solution for clinical application. METHODS: In total, 10 participants with AO/OTA type 41B2 tibial plateau fractures diagnosed by preoperative imaging examinations were enrolled in this study between May 2019 and May 2022. They were 5 males and 5 females, with an average age of 45.6 ± 11.3 years old (range 27-62 years old). All of them had closed fractures, including 6 cases with anterior cruciate ligament (ACL) tibial insertion avulsion fractures, 1 case with medial collateral ligament (MCL) tear, and 4 cases with a lateral meniscus tear. From injury through surgery, the entire time frame was 4.0 ± 1.5 days (range, 2-7 days). Following indirect percutaneous reduction assisted by TiRobot, the Jail method was used to treat all patients with minimally invasive internal fixation. Patients with ligament or meniscus injurieswere treated with arthroscopic surgery in one stage. The standardized functional exercise was performed postoperatively. The knee function was measured using the Hospital for Special Surgery (HSS) score, and the fracture reduction was assessed through the Rasmussen radiology score. RESULTS: All patients were followed up for 12.7 ± 6.8 months (6-24 months).The fracture healing time was 11.8 ± 0.8 weeks (10-13 weeks), and the X-rays revealed satisfactory fracture reduction.The knee joint's Rasmussen score was 17.8 ± 0.4 (in the range of 17-18) a year after the procedure, with 8 patients receiving outstanding ratings and 2 cases receiving satisfactory scores. The HSS score was 93.8 ± 2.3 (range, 89 to 96), of which 10 cases were excellent. The motion range of the kneewas 138.7°±2.7° (range, -5° to 0° to 135°). No adverse effects or serious complications, such as internal fixation failure, postoperative infection, popliteal vascular injury, and common peroneal nerve injury, were observed during the last follow-up visit. CONCLUSIONS: The intelligent assistance and accurate guidance of TiRobot can simplify and standardize procedures of percutaneous minimally invasive fixation in theSchatzker type Ⅲ tibial plateau fracture treatment. This technique increases the precision of indirect percutaneous reduction and screw fixation while minimizing bone grafting.

Er:YAG laser combined with botulinum toxin A for patients with local syringomas: A preliminary report.

Syringoma is a common but refractory benign skin tumor. Conventional treatment, such as ultra-pulsed carbon dioxide (CO2 ) laser or cryotherapy, often requires multiple treatment and can easily cause prolonged erythema, scarring, or depression, which are frustrating, so there is an urgent need to seek a safer and more effective method. In this article, we tried to demonstrate the Er:YAG laser combined with botulinum toxin A (BTXA) as a safer and more efficacious method for treating syringomas. MATERIALS AND METHODS: Twenty-one patients with local syringomas were treated with erbium laser ablation. Immediately after laser treatment, approximately 10 units of BTXA were sprayed on the wound for 10 min. RESULT: In total, 21 patients underwent 1.62 ± 0.74 treatments; their Periorbital Syringoma Severity Index (PSSI) score declined from 4.19 (before treatment) to 1.10 (after treatment), and the number of treatments was significantly lower than those reported in previous literature using the erbium laser alone. CONCLUSION: The Er:YAG laser combined with botulinum toxin A for the treatment of syringoma is a safer and more effective treatment than traditional treatment methods.

Bioengineering Comamonas testosteroni CNB-1: a robust whole-cell biocatalyst for efficient PET microplastic degradation.

The escalating crisis of polyethylene terephthalate (PET) microplastic contamination in biological wastewater treatment systems is a pressing environmental concern. These microplastics inevitably accumulate in sewage sludge due to the absence of effective removal technologies. Addressing this urgent issue, this study introduces a novel approach using DuraPETase, a potent enzyme with enhanced PET hydrolytic activity at ambient temperatures. Remarkably, this enzyme was successfully secreted from Comamonas testosteroni CNB-1, a dominant species in the active sludge. The secreted DuraPETase showed significant hydrolytic activity toward p-NPB and PET nanoplastics. Furthermore, the CNB-1 derived whole-cell biocatalyst was able to depolymerize PET microplastics under ambient temperature, achieving a degradation efficiency of 9% within 7 days. The CNB-1-based whole biocatalysts were also capable of utilizing PET degradation intermediates, such as terephthalic acid (TPA) and ethylene glycol (EG), and bis(2-hydroxyethyl)-TPA (BHET), for growth. This indicates that it can completely mineralize PET, as opposed to merely breaking it down into smaller molecules. This research highlights the potential of activated sludge as a potent source for insitu microplastic removal.

A Substructure Condensed Approach for Kinetostatic Modeling of Compliant Mechanisms with Complex Topology.

Compliant mechanisms with complex topology have previously been employed in various precision devices due to the superiorities of high precision and compact size. In this paper, a substructure condensed approach for kinetostatic analysis of complex compliant mechanisms is proposed to provide concise solutions. In detail, the explicit relationships between the theoretical stiffness matrix, element stiffness matrix, and element transfer matrix for the common flexible beam element are first derived based on the energy conservation law. The transfer matrices for three types of serial-parallel substructures are then developed by combining the equilibrium equations of nodal forces with the transfer matrix approach, so that each branch chain can be condensed into an equivalent beam element. Based on the derived three types of transfer matrices, a kinetostatic model describing only the force-displacement relationship of the input/output nodes is established. Finally, two typical precision positioning platforms with complex topology are employed to demonstrate the conciseness and efficiency of this modeling approach. The superiority of this modeling approach is that the input/output stiffness, coupling stiffness, and input/output displacement relations of compliant mechanisms with multiple actuation forces and complex substructures can be simultaneously obtained in concise and explicit matrix forms, which is distinct from the traditional compliance matrix approach.

[Microplastics in wastewater treatment: current status and future trends].

Microplastics (MPs) have been detected in many ecosystems, such as the ocean, land and the atmosphere. A large number of MPs in urban sewage are trapped in the activated sludge by sewage treatment plants, but tens of thousands of MPs 'escape' the treatment and are discharged into the nature. Meanwhile, most of the MPs are transferred into the activated sludge during sewage treatment, and the sludge will be further used in agriculture, leading to secondary pollution of the MPs. Through literature research, we summarized the sources, distribution and hazards of MPs in the environment, the treatment of MPs with activated sludge, and the treatment methods of residual MPs in activated sludge, and summed up the potentials of biotechnology and synthetic biology in the genetic modification of key bacteria in activated sludge to endow them with MPs-degrading ability. The conclusion is expected to serve as a reference for optimizing the biodegradation of MPs in wastewater treatment plants.

Analytical Compliance Equations of Generalized Elliptical-Arc-Beam Spherical Flexure Hinges for 3D Elliptical Vibration-Assisted Cutting Mechanisms.

Elliptical vibration-assisted cutting technology has been widely applied in complicated functional micro-structured surface texturing. Elliptical-arc-beam spherical flexure hinges have promising applications in the design of 3D elliptical vibration-assisted cutting mechanisms due to their high motion accuracy and large motion ranges. Analytical compliance matrix formulation of flexure hinges is the basis for achieving high-precision positioning performance of these mechanisms, but few studies focus on this topic. In this paper, analytical compliance equations of spatial elliptic-arc-beam spherical flexure hinges are derived, offering a convenient tool for analysis at early stages of mechanism design. The mechanical model of a generalized flexure hinge is firstly established based on Castigliano's Second Theorem. By introducing the eccentric angle as the integral variable, the compliance matrix of the elliptical-arc-beam spherical flexure hinge is formulated. Finite element analysis is carried out to verify the accuracy of the derived analytical compliance matrix. The compliance factors calculated by the analytical equations agree well with those solved in the finite element analysis for the maximum error; average relative error and relative standard deviation are 8.25%, 1.83% and 1.78%, respectively. This work lays the foundations for the design and modeling of 3D elliptical vibration-assisted cutting mechanisms based on elliptical-arc-beam spherical flexure hinges.

Preparation and characterization of biodegradable trilayer films based on starch and polyester.

The trilayer films of polyester/starch/polyester with different starch/polyester layer thickness ratios were prepared by co-extrusion blowing. FTIR and SEM results showed the successful fabrication of trilayer films. The crystallinity of trilayer films gradually increased as the thickness of polyester layer increased. Dynamic mechanical analysis was used to investigate the compatibility between starch and polyester. The presence of polyester layer significantly increased the tensile strength and water contact angle of starch film. All trilayer films had lower water vapor permeability than the starch film, and lower oxygen permeability than the polyester film. The trilayer films were degraded to a much greater extent compared with the polyester film. The weight loss of P10 trilayer film in 120 days is about 80% through degradation test. These results suggested that the polyester/starch/polyester films with excellent mechanical and hydrophobic properties could serve as packaging material for wider applications.

Iron overload induced death of osteoblasts in vitro: involvement of the mitochondrial apoptotic pathway.

BACKGROUND: Iron overload is recognized as a new pathogenfor osteoporosis. Various studies demonstrated that iron overload could induce apoptosis in osteoblasts and osteoporosis in vivo. However, the exact molecular mechanisms involved in the iron overload-mediated induction of apoptosis in osteoblasts has not been explored. PURPOSE: In this study, we attempted to determine whether the mitochondrial apoptotic pathway is involved in iron-induced osteoblastic cell death and to investigate the beneficial effect of N-acetyl-cysteine (NAC) in iron-induced cytotoxicity. METHODS: The MC3T3-E1 osteoblastic cell line was treated with various concentrations of ferric ion in the absence or presence of NAC, and intracellular iron, cell viability, reactive oxygen species, functionand morphology changes of mitochondria and mitochondrial apoptosis related key indicators were detected by commercial kits. In addition, to further explain potential mechanisms underlying iron overload-related osteoporosis, we also assessed cell viability, apoptosis, and osteogenic differentiation potential in bone marrow-derived mesenchymal stemcells(MSCs) by commercial kits. RESULTS: Ferric ion demonstrated concentration-dependent cytotoxic effects on osteoblasts. After incubation with iron, an elevation of intracelluar labile iron levels and a concomitant over-generation of reactive oxygen species (ROS) were detected by flow cytometry in osteoblasts. Nox4 (NADPH oxidase 4), an important ROS producer, was also evaluated by western blot. Apoptosis, which was evaluated by Annexin V/propidium iodide staining, Hoechst 33258 staining, and the activation of caspase-3, was detected after exposure to iron. Iron contributed to the permeabilizatio of mitochondria, leading to the release of cytochrome C (cyto C), which, in turn, induced mitochondrial apoptosis in osteoblasts via activation of Caspase-3, up-regulation of Bax, and down-regulation of Bcl-2. NAC could reverse iron-mediated mitochondrial dysfunction and blocked the apoptotic events through inhibit the generation of ROS. In addition, iron could significantly promote apoptosis and suppress osteogenic differentiation and mineralization in bone marrow-derived MSCs. CONCLUSIONS: These findings firstly demonstrate that the mitochondrial apoptotic pathway involved in iron-induced osteoblast apoptosis. NAC could relieved the oxidative stress and shielded osteoblasts from apoptosis casused by iron-overload. We also reveal that iron overload in bone marrow-derived MSCs results in increased apoptosis and the impairment of osteogenesis and mineralization.

[Forest lighting fire forecasting for Daxing'anling Mountains based on MAXENT model].

Daxing'anling Mountains is one of the areas with the highest occurrence of forest lighting fire in Heilongjiang Province, and developing a lightning fire forecast model to accurately predict the forest fires in this area is of importance. Based on the data of forest lightning fires and environment variables, the MAXENT model was used to predict the lightning fire in Daxing' anling region. Firstly, we studied the collinear diagnostic of each environment variable, evaluated the importance of the environmental variables using training gain and the Jackknife method, and then evaluated the prediction accuracy of the MAXENT model using the max Kappa value and the AUC value. The results showed that the variance inflation factor (VIF) values of lightning energy and neutralized charge were 5.012 and 6.230, respectively. They were collinear with the other variables, so the model could not be used for training. Daily rainfall, the number of cloud-to-ground lightning, and current intensity of cloud-to-ground lightning were the three most important factors affecting the lightning fires in the forest, while the daily average wind speed and the slope was of less importance. With the increase of the proportion of test data, the max Kappa and AUC values were increased. The max Kappa values were above 0.75 and the average value was 0.772, while all of the AUC values were above 0.5 and the average value was 0. 859. With a moderate level of prediction accuracy being achieved, the MAXENT model could be used to predict forest lightning fire in Daxing'anling Mountains.