Enhancing the SCC Resistance of the Anchor Steel with Microalloying in a Simulated Mine Environment.

This work explored a new idea for enhancing the resistance to stress corrosion cracking (SCC) of mining anchor steel through microalloying. Microalloyed anchor steels with Nb, Cu, Ni, Sb, and C were prepared through vacuum smelting and hot rolling. Electrochemical measurements, slow strain rate tensile (SSRT) tests, and fracture morphology observations were used to study the electrochemical and SCC behavior in the simulated mine environment. The results proved that the microstructure of microalloyed steels varies slightly. Adding Ni, Cu, and Sb can improve the mechanical properties of the anchor steel, while reducing C content decreases tensile strength as a result of loss of the solution-strengthening effect. The addition of Sb, Cu, Ni, and reducing the content of C enhances the resistance to corrosion and SCC by mitigating anodic dissolution (AD), while adding Nb improves SCC resistance by inhibiting hydrogen embrittlement (HE). The combined addition of 1% Ni, 0.5% Cu, 0.05% Nb, 0.1% Sb, and 0.5% C presented the highest SCC resistance, which is a promising prospect for the development of high-performance, low-alloy anchor steels. The combined addition of 1% Ni, 0.5% Cu, 0.05% Nb, and 0.1% Sb resulted in the inhibition of electrochemical reactions and corrosion. As a result of the synergistic effect of the microalloy, both AD and HE mechanisms were simultaneously inhibited, which greatly enhanced SCC resistance.

Application of Spinal Robotic Navigation Technology to Minimally Invasive Percutaneous Treatment of Spinal Fractures: A Clinical, Non-Randomized, Controlled Study.

OBJECTIVE: To introduce a new robotic navigation system that assists pedicle screw implantation and verify the accuracy and stability of the system. METHODS: Pedicle screw placements were performed on the thoracic vertebrae (T)9-Lumbar vertebrae (L)5 thoracolumbar vertebrae of cadavers using robotic guidance. The operative duration, puncture success, correction, and correction time were assessed. Additionally, a total of 30 thoracolumbar fractures from September 2017 until June 2019 were included in a clinical study. Two groups were evaluated: the robotic guidance group and freehand group. Both sexes were evaluated. Mean ages were 47.0 and 49.1 years, respectively, in the robotic and freehand groups. Inclusion criteria was age >18 years and a thoracolumbar fracture. Intervention was the operative treatment of thoracolumbar fractures. Outcome parameters were the operation time, intraoperative bleeding, and fluoroscopic data. The accuracy of the pedicle screw placement and screw penetration rate of the two groups were compared using intraoperative fluoroscopic axial images. RESULTS: The success rate for 108 one-time nail placements in cadavers was 88% and two-time nail placement was 100%. Vertebral punctures at L5 took the longest to perform and achieve correction. Clinically, there were no significant differences in patients' sex, body mass index, age distribution, or intraoperative bleeding between the groups. The average X-ray exposure time for patients and operators were 37.69 ± 9.24 s and 0 s in the robotic group (significantly lower than in the freehand group: 81.24 ± 6.97 s vs 56.29 ± 7.93 s, respectively). Success rates for one-time screw placements were 98.64 and 88.46% in the robotic and freehand groups, respectively, which is significant. Screw penetration rates (1.36% vs 11.54%, robotic vs freehand), were significantly different. CONCLUSIONS: The robotic system improved the accuracy and safety of pedicle screw internal fixation and reduced patients' and operators' intraoperative radiation exposure.

Neuroprotective effect of hydrogen sulfide against glutamate-induced oxidative stress is mediated via the p53/glutaminase 2 pathway after traumatic brain injury.

Several reports suggest that hydrogen sulfide (H2S) exerts multiple biological and physiological effects on the pathogenesis of traumatic brain injury (TBI). However, the exact molecular mechanism involved in this effect is not yet fully known. In this study, we found that H2S alleviated TBI-induced motor and spatial memory deficits, brain pathology, and brain edema. Moreover, sodium hydrosulfide (NaHS), an H2S donor, treatment markedly increased the expression of Bcl-2, while inhibited the expression of Bax and Cleaved caspase-3 in TBI-challenged rats. Tunnel staining also demonstrated these results. Treatment with NaHS significantly reduced the glutamate and glutaminase 2 (GLS-2) protein levels, and glutamate-mediated oxidative stress in TBI-challenged rats. Furthermore, we demonstrated that H2S treatment inhibited glutamate-mediated oxidative stress through the p53/GLS-2 pathway. Therefore, our results suggested that H2S protects brain injury induced by TBI through modulation of the glutamate-mediated oxidative stress in the p53/GLS-2 pathway-dependent manner.

Robot-assisted percutaneous vertebroplasty under local anaesthesia for osteoporotic vertebral compression fractures: a retrospective, clinical, non-randomized, controlled study.

RESEARCH AND DESIGN: A retrospective, clinical, non-randomized, controlled study. OBJECTIVE: To evaluate the application of a new spinal navigation robot on percutaneous vertebroplasty (PVP) under local anaesthesia. METHODS: The result of inserting the puncture needle into the simulated pedicle was observed in vitro. Thirty patients with thoracolumbar fractures were enrolled. The basic data, operation-related data and clinical effect scores were recorded. The learning curve of robot-guided surgery was analysed. RESULTS: The maximum yaw angle of the puncture needle implanting into the simulated pedicle is 0.5°. The operation time (33.93 ± 5.97 min vs. 53.75 ± 14.08 min, p = 0.000) and the average X-ray exposure time (31.43 ± 4.93 s vs. 54.69 ± 2.15 s, p = 0.000) was significantly less in the robot group. The surgeons quickly mastered the technique of robot-guided pedicle puncture after three surgeries. CONCLUSIONS: Robot-assisted PVP could performed under local anaesthesia with the new robot.

Application of binocular visual navigation technique in diaphyseal fracture reduction.

BACKGROUND: Computer-assisted surgical navigation techniques have shown promise; however, currently popular systems have limitations. This paper presents the characterization and application of a binocular visual navigation technique in diaphyseal fracture reduction. METHODS: A binocular visual tracker (MicronTracker) was introduced to reduce diaphyseal fractures. A transformation matrix was used to acquire the reduction parameters. A transverse diaphyseal fracture was used as a control group. RESULTS: Precision tests were performed with the binocular system using a simulation femoral model with a transverse fracture 12 times. All residual deformations were compared and P < 0.01. CONCLUSIONS: The binocular visual navigation technique produces good results with advantages of flexibility and high positional accuracy and shows promise. The MicronTracker might lead to further application in the remote navigation field.

The carbon footprint of large- and mid-scale hydropower in China: Synthesis from five China's largest hydro-project.

The past two decades have witnessed growing global concern about excessive greenhouse gas (GHG) emissions by reservoirs and the development of hydropower. Literature review showed that life cycle GHG emissions per energy production of collected global dataset ranged from 0.04 to 237.0 gCO2eq/kW⋅h, with a mean of 25.8 ±â€¯3.0 gCO2eq/kW⋅h. Synthesis from the China's five largest hydro-projects and other publications estimated that the large- and mid-scale hydro-projects in China had a carbon footprint between 6.2 gCO2eq/kWh and 34.6 gCO2eq/kWh, with a mean value of 19.2 ±â€¯6.8 gCO2eq/kWh (mean ±â€¯sd.). Over 80% of the carbon footprint of the hydro-projects could be conservatively allocated to hydroelectricity generation, while the rest could then be allocated to flood control services. In the Three Gorges Dam Project, the allocated life cycle GHG emissions per energy production of its hydroelectricity production was estimated to be 17.8 gCO2eq/kW⋅h. GHG emissions from reservoir sediments and in the phase of operation and maintenance were still uncertain. There is still a need of in-depth research on reservoir carbon cycling to quantify net reservoir GHG emissions.

Natural variation in GmGBP1 promoter affects photoperiod control of flowering time and maturity in soybean.

The present study screened for polymorphisms in coding and non-coding regions of the GmGBP1 gene in 278 soybean accessions with variable maturity and growth habit characteristics under natural field conditions in three different latitudes in China. The results showed that the promoter region was highly diversified compared with the coding sequence of GmGBP1. Five polymorphisms and four haplotypes were closely related to soybean flowering time and maturity through association and linkage disequilibrium analyses. Varieties with the polymorphisms SNP_-796G, SNP_-770G, SNP_-307T, InDel_-242normal, SNP_353A, or haplotypes Hap-3 and Hap-4 showed earlier flowering time and maturity in different environments. The shorter growth period might be largely due to higher GmGBP1 expression levels in soybean that were caused by the TCT-motif with SNP_-796G in the promoter. In contrast, the lower expression level of GmGBP1 in soybean caused by RNAi interference of GmGBP1 resulted in a longer growth period under different day lengths. Furthermore, the gene interference of GmGBP1 also caused a reduction in photoperiod response sensitivity (PRS) before flowering in soybean. RNA-seq analysis on GmGBP1 underexpression in soybean showed that 94 and 30 predicted genes were significantly upregulated and downregulated, respectively. Of these, the diurnal photoperiod-specific expression pattern of three significant flowering time genes GmFT2a, GmFT5a, and GmFULc also showed constantly lower mRNA levels in GmGBP1-i soybean than in wild type, especially under short day conditions. Together, the results showed that GmGBP1 functioned as a positive regulator upstream of GmFT2a and GmFT5a to activate the expression of GmFULc to promote flowering on short days.

A computer aided measurement method for unstable pelvic fractures based on standardized radiographs.

BACKGROUND: To set up a method for measuring radiographic displacement of unstable pelvic ring fractures based on standardized X-ray images and then test its reliability and validity using a software-based measurement technique. METHODS: Twenty-five patients that were diagnosed as AO/OTA type B or C pelvic fractures with unilateral pelvis fractured and dislocated were eligible for inclusion by a review of medical records in our clinical centre. Based on the input pelvic preoperative CT data, the standardized X-ray images, including inlet, outlet, and anterior-posterior (AP) radiographs, were simulated using Armira software (Visage Imaging GmbH, Berlin, Germany). After representative anatomic landmarks were marked on the standardized X-ray images, the 2-dimensional (2D) coordinates of these points could be revealed in Digimizer software (Model: Mitutoyo Corp., Tokyo, Japan). Subsequently, we developed a formula that indicated the translational and rotational displacement patterns of the injured hemipelvis. Five separate observers calculated the displacement outcomes using the established formula and determined the rotational patterns using a 3D-CT model based on their overall impression. We performed 3D reconstruction of all the fractured pelvises using Mimics (Materialise, Haasrode, Belgium) and determined the translational and rotational displacement using 3-matic suite. The interobserver reliability of the new method was assessed by comparing the continuous measure and categorical outcomes using intraclass correlation coefficient (ICC) and kappa statistic, respectively. RESULT: The interobserver reliability of the new method for translational and rotational measurement was high, with both ICCs above 0.9. Rotational outcome assessed by the new method was the same as that concluded by 3-matic software. The agreement for rotational outcome among orthopaedic surgeons based on overall impression was poor (kappa statistic, 0.250 to 0.426). Compared with the 3D reconstruction outcome, the interobserver reliability of the formula method for translational and rotational measures was perfect with both ICCs more than 0.9. CONCLUSIONS: The new method for measuring displacement using a formula was reliable, and could minimise the measurement errors and maximise the precision of pelvic fracture description. Furthermore, this study was useful for standardising the operative plan and establishing a theoretical basis for robot-assisted pelvic fracture surgery based on 2-D radiographs.

Robot-musculoskeletal dynamic biomechanical model in robot-assisted diaphyseal fracture reduction.

A number of issues that exist in common fracture reduction surgeries can be mitigated by robot-assisted fracture reduction. However, the safety of patients and the performance of the robot, which are closely related to the muscle forces, are important indexes that restrict the development of robots. Though researchers have done a great deal of work on the biomechanics of the musculoskeletal system, the dynamics of the musculoskeletal system, particularly the aspects related to the function of the robot, is not well understood. For this reason, we represent the complex biological system by establishing a dynamic biomechanical model based on the Hill muscle model and the Kane method for the robot that we have developed and the musculoskeletal system. We analyzed the relationship between the motion and force of the bone fragments and the robot during a simulation of a robot-assisted fracture reduction. The influence of the muscle force on the robot system was predicted and managed. The simulation results provide a basis for a fracture reduction path plan that ensures patient safety and a useful reference for the mechanical design of the robot.

A visual servo-based teleoperation robot system for closed diaphyseal fracture reduction.

Common fracture treatments include open reduction and intramedullary nailing technology. However, these methods have disadvantages such as intraoperative X-ray radiation, delayed union or nonunion and postoperative rotation. Robots provide a novel solution to the aforementioned problems while posing new challenges. Against this scientific background, we develop a visual servo-based teleoperation robot system. In this article, we present a robot system, analyze the visual servo-based control system in detail and develop path planning for fracture reduction, inverse kinematics, and output forces of the reduction mechanism. A series of experimental tests is conducted on a bone model and an animal bone. The experimental results demonstrate the feasibility of the robot system. The robot system uses preoperative computed tomography data to realize high precision and perform minimally invasive teleoperation for fracture reduction via the visual servo-based control system while protecting surgeons from radiation.

Intramedullary nailing versus plating for distal tibia fractures without articular involvement: a meta-analysis.

BACKGROUND: The choice between intramedullary (IM) nailing or plating of distal tibia fractures without articular involvement remains controversial. A meta-analysis of randomized controlled trials (RCTs) and observational studies was performed to compare IM nailing with plating for distal tibia fractures without articular involvement and to determine the dominant strategy. MATERIALS AND METHODS: The PubMed, Embase, Cochrane Library databases, Chinese Wan-Fang Database, and China National Knowledge Infrastructure were searched. RESULTS: Twenty-eight studies, which included 1863 fractures, met the eligible criteria. The meta-analysis did not identify a statistically significant difference between the two treatments in terms of the rate of deep infection, delayed union, removal of instrumentation, or secondary procedures either in the RCT or retrospective subgroups. IM nailing was associated with significantly more malunion events and a higher incidence of knee pain in the retrospective subgroup and across all the studies, but not significantly in the RCT subgroup, and a lower rate of delayed wound healing and superficial infection both in the RCT and retrospective subgroups relative to plating. A meta-analysis of the functional scores or questionnaires was not possible because of the considerable variation among the included studies, and no significant differences were observed. CONCLUSIONS: Evidence suggests that both IM nailing and plating are appropriate treatments as IM nailing shows lower rate of delayed wound healing and superficial infection and plating may avoid malunion and knee pain. These findings should be interpreted with caution, however, because of the heterogeneity of the study designs. Large, rigorous RCTs are required.

Advancing computer-assisted orthopaedic surgery using a hexapod device for closed diaphyseal fracture reduction.

BACKGROUND: Surgical complications such as healing problems, in fractures treated using the Arbeitsgemeinschaft für Osteosynthesefragen (AO) technique, present functional and economic challenges to patients and treatment dilemmas for surgeons. Computer-assisted orthopaedic surgery using minimally invasive techniques focused on biological osteosynthesis is a novel direction for fracture treatment. METHOD: We modified the hexapod computer-assisted fracture reduction system by introducing a new reduction strategy, building a new system configuration and upgrading the corresponding software. We then validated the entire system, using a fracture model of bovine femur. RESULTS: Precision tests were performed seven times on a bovine femur with a transverse fracture. Residual deviation was 1.23 ± 0.60 mm in axial deflection, 1.04 ± 0.47 mm in translation, 2.34 ± 1.79° in angulation and 2.83 ± 0.96° in rotation. CONCLUSION: Our new reduction system described here is detachable, flexible and more precise in coordinate transformations. The detachable, modular design will allow for more analogous applications in the future. Copyright © 2014 John Wiley & Sons, Ltd.

Preoperative trajectory planning for closed reduction of long-bone diaphyseal fracture using a computer-assisted reduction system.

BACKGROUND: Balancing reduction accuracy with soft-tissue preservation is a challenge in orthopaedics. Computer-assisted orthopaedic surgery (CAOS) can improve accuracy and reduce radiation exposure. However, previous reports have not summarized the fracture patterns to which CAOS has been applied. METHODS: We used a CAOS system and a stereolithography model to define a new fracture classification. Twenty reduction tests were performed to evaluate the effectiveness of preoperative trajectory planning. RESULTS: Twenty tests ran automatically and smoothly. Only three slight scratches occurred. Seventy-six path points represented displacement deviations of < 2 mm (average < 1 mm) and angulation deviation of < 1.5°. DISCUSSION: Because of the strength of muscles, mechanical sensors are used to prevent iatrogenic soft-tissue injury. Secondary fractures are prevented mainly through preoperative trajectory planning. Based on our data, a 1 mm gap between the edges of fractures spikes is sufficient to avoid emergency braking from spike interference.

Acute spinal cord injury in rats induces autophagy activation.

AIM: Autophagy is an important process that balances cellular protein synthesis and degradation and is involved in many physiological and pathological conditions. However, the precise role of autophagy has not yet been defined in the model of spinal cord injury (SCI). MATERIAL AND METHODS: Here, we utilized a hemisection model of acute SCI to elucidate the role of autophagy in the pathological processes underlying SCI. RESULTS: LC3B-II, a well-known marker of autophagy, was immunohistochemically detected 4H after SCI, peaked at 3D, and decreased at 21D. Hematoxylin-eosin (HE) staining confirmed accurate spinal cord hemisection, which was accompanied by both neuronal swelling and shrunken neurons with darkly stained, condensed nuclei. These findings suggest that the process of autophagy is related with pathological changes following SCI. CONCLUSION: Our results indicate autophagy is involved in the pathological changes after SCI, and potential therapies to promote neuronal regeneration following SCI should target the mechanism of autophagy.

Negative-pressure wound therapy enhances local inflammatory responses in acute infected soft-tissue wound.

Clinical studies found that negative-pressure wound therapy (NPWT) displayed significant clinical benefits in the healing of infected wounds. However, the effect of NPWT on local inflammatory responses in acute infected soft-tissue wound has not been investigated thoroughly. The purpose of this study was to test the impact of NPWT on local expression of proinflammatory cytokines, amount of neutrophils, and bacterial bioburden in wound from acute infected soft-tissue wounds. Full-thickness wounds were created on the back of rabbits, and were inoculated with Staphylococcus aureus strain ATCC29213. The wounds were treated with sterile saline-moistened gauze dressings and NPWT with continuous negative pressure (-125 mmHg). Wound samples were harvested on days 0 (6 h after bacterial inoculation), 2, 4, 6, and 8 at the center of wound beds before irrigation for real-time PCR analysis of gene expression of IL-1ß, IL-8, and TNF-α. Wound biopsies were examined histologically for neutrophil quantification in different layers of tissue. Quantitative bacterial cultures at the same time point were analyzed for bacterial clearance. Application of NPWT to acute infected wounds in rabbits was compared with treatment with sterile saline-moistened gauze, over an 8-day period. NPWT-treated wounds exhibited earlier and greater peaking of IL-1ß and IL-8 expression and decrease in TNF-α expression over the early 4 days (P < 0.05). Furthermore, histologic examination revealed that significantly increased neutrophil count was observed in the shallow layer in wound biopsies of NPWT treatment at day 2 (P < 0.001). In addition, there was a statistically significant decrease of bacteria load from baseline (day 0) at days 2 and 8 in NPWT group (P < 0.05). In conclusion, this study demonstrates that NPWT of acute infected soft-tissue wounds leads to increased local IL-1ß and IL-8 expression in early phase of inflammation, which may trigger accumulation of neutrophils and thus accelerate bacterial clearance. Meanwhile, the success of NPWT in the treatment of acute wounds can attenuate the expression of TNF-α, and the result may partly explain how NPWT can avoid significantly impairing wound healing.

Highly enantioselective Michael addition promoted by a new diterpene-derived bifunctional thiourea catalyst: a doubly stereocontrolled approach to chiral succinimide derivatives.

A doubly stereocontrolled organocatalytic asymmetric Michael addition to the synthesis of substituted succinimides is described. Starting from aldehydes and maleimides, both enantiomers of the succinimides could be obtained in high to excellent yields (up to 98%) and enantioselectivities (up to 99%) when one of the two special chiral diterpene-derived bifunctional thioureas was individually used as a catalyst. Moreover, these catalysts can be efficiently used in large-scale catalytic synthesis with the same level of yield and enantioselectivity.

A removable hybrid robot system for long bone fracture reduction.

In traditional long bone fracture reduction surgery, there are some drawbacks such as low accuracy, high radiation for surgeons and a risk of infection. To overcome these disadvantages, a removable hybrid robot system is developed, which integrates a removable series-parallel mechanism with a motor-double cylinder (MDC) driven mode. This paper describes the mechanism in detail, analyses the principle and the method of the fracture reduction, presents the surgical procedure, and verifies the reduction accuracy by experiments with bone models. The results are shown as follows. The mean deviations of the axial displacement and lateral displacement are 1.60mm and 1.26 mm respectively. The standard deviations are 0.69 mm and 0.30 mm. The mean deviations of the side angle and turn inward are 2.06° and 2.22° respectively. The standard deviations are 0.50° and 0.99°. This minimally invasive robot features high accuracy and zero radiation for surgeons, and is able to conduct fracture reduction for long bones.

Projective invariant biplanar registration of a compact modular orthopaedic robot.

This paper presents a compact orthopedic robot designed with modular concept. The layout of the modular configuration is adaptive to various conditions such as surgical workspace and targeting path. A biplanar algorithm is adopted for the mapping from the fluoroscopic image to the robot, while the former affine based method is satisfactory only when the projection rays are basically perpendicular to the reference coordinate planes. This paper introduces the area cross-ratio as a projective invariant to improve the registration accuracy for non-orthogonal orientations, so that the robotic system could be applied to more orthopedic procedures under various C-Arm orientation conditions. The system configurations for femoral neck screw and sacroiliac screw fixation are presented. The accuracy of the robotic system and its efficacy for the two typical applications are validated by experiments.

Autophagy reduces neuronal damage and promotes locomotor recovery via inhibition of apoptosis after spinal cord injury in rats.

Autophagy is an intracellular catabolic mechanism that maintains the balance of proteins, lipids and aging organelles. 3-Methyladenine (3-MA) is a selective inhibitor of autophagy, whereas rapamycin, an antifungal agent, is a specific inducer of autophagy, inhibiting the protein mammalian target of rapamycin. In the present study, we examined the role of autophagy, inhibited by 3-MA and enhanced by rapamycin, in a model of acute spinal cord injury in rats. We found that rapamycin could significantly increase the expression of microtubule-associated protein 1 light chain 3 (LC3) and Beclin1 at the injury site. At the same time, the number of neurons and astrocytes with LC3 positive in the spinal cord was upregulated with time. In addition, administration of rapamycin produced an increase in the Basso, Beattie and Bresnahan scores of injured rats, indicating high recovery of locomotor function. Furthermore, expression of the proteins Bcl-2 and Bax was upregulated and downregulated, respectively. By contrast, the results for rats treated with 3-MA, which inhibits autophagy, were the opposite of those seen with the rapamycin-treated rats. These results show that induction of autophagy can produce neuroprotective effects in acute spinal cord injury in rats via inhibition of apoptosis.

A femur fracture reduction method based on anatomy of the contralateral side.

Femoral fractures may result in loss of the original femur anatomy, without leaving a direct source of reference for femur reduction procedures. Femoral configuration renders it feasible to redesign the original femur based on the information obtained from the contralateral femur. In this report, we describe a method to rebuild the original femur based on the contralateral side as the reference after ascertaining the bilateral symmetry of the body. The method was tested on animals using the spine model and the experimental results are discussed briefly.