Simulation and Experimental Study on the Precision Molding of Irregular Vehicle Glass Components.

The high level of stress and dimension deviation induced by glass molding are the main causes of the low yield rate of large, irregular glass components on vehicles. To solve this issue, a numerical model of large glass component molding was established in this study, which aimed to analyze the dominant factors of molding quality and achieve a synergistic balance between quality characteristics and energy consumption. The results show that molding temperature is the dominant factor affecting the energy consumption and residual stress, and the molding pressure is the main factor affecting the dimension deviation. Furthermore, the NSGA-II optimization algorithm was used to optimize the maximum residual stress, dimension deviation, and energy consumption with the numerical results. The combination of a heating rate of 1.95 °C/s, holding time of 158 s, molding temperature of 570 °C, molding pressure of 34 MPa, and cooling rate of 1.15 °C/s was determined to be the optimized scheme. The predictive error of the numerical result, based on the optimized scheme, was experimentally verified to be less than 20%. It proved the accuracy of the model in this study. These results can provide guidance for the subsequent precision molding of large, irregular glass components.

Development of a Hybrid Intelligent Process Model for Micro-Electro Discharge Machining Using the TTM-MDS and Gaussian Process Regression.

This paper proposed a hybrid intelligent process model, based on a hybrid model combining the two-temperature model (TTM) and molecular dynamics simulation (MDS) (TTM-MDS). Combined atomistic-continuum modeling of short-pulse laser melting and disintegration of metal films [Physical Review B, 68, (064114):1-22.], and Gaussian process regression (GPR), for micro-electrical discharge machining (micro-EDM) were also used. A model of single-spark micro-EDM process has been constructed based on TTM-MDS model to predict the removed depth (RD) and material removal rate (MRR). Then, a GPR model was proposed to establish the relationship between input process parameters (energy area density and pulse-on duration) and the process responses (RD and MRR) for micro-EDM machining. The GPR model was trained, tested, and tuned using the data generated from the numerical simulations. Through the GPR model, it was found that micro-EDM process responses can be accurately predicted for the chosen process conditions. Therefore, the hybrid intelligent model proposed in this paper can be used for a micro-EDM process to predict the performance.

An advanced scaling model system for non-condensable gas steam assisted gravity drainage recovery process.

Physical modeling is critical to study the performance of certain operation in heavy oil reservoirs. A well-designed experiment should guarantee the information gathered from lab would be applied to predict the thermal process in the field. To meet this requirement, the initial and boundary condition similarity between lab and field should be satisfied. It is reasonable to follow certain scaling criteria to fabricate the physical model. In addition to these conventional guidelines, this paper makes following recommendations to ensure a successful thermal recovery experiment,•To control and mitigate the steam channeling between the sand-pack and apparatus wall, the back wall is designed as it can be pushed enough to increase contact pressure.•Heat loss should be handled carefully, which impacting steam chamber growing and causing heat accumulation around the model.•A data acquisition system, based on PXI platform and Labview software, for the thermal recovery experiments had been proved valuable in evaluating the spreading progress of steam chamber.

Influence of extracellular nanovesicles derived from adipose-derived stem cells on nucleus pulposus cell from patients with intervertebral disc degeneration.

An increasing number of individuals are suffering from lower back and neck pain caused by intervertebral disc degeneration each year. Although the application of mesenchymal stem cells (MSCs) has provided desirable results in the treatment of intervertebral disc degeneration, there are multiple risks associated with the directed application of MSCs. An increasing number of studies have suggested that stem cells, through the release of extracellular nanovesicles, have vital functions in tissue regeneration and repair with low risk. The present study investigated the effect of extracellular nanovesicles derived from adipose-derived stem cells (ADSCs) on nucleus pulposus (NP) cells from patients with intervertebral disc degeneration. Human NP cells were obtained from patients with intervertebral disc degeneration undergoing surgical procedures in addition to ADSCs from liposuction patients. ADSC-derived extracellular nanovesicles were isolated and characterized. The differentiation and biological activity of NP cells cultured with or without ADSC-derived extracellular nanovesicles were assessed and inflammatory factors and intervertebral disc degeneration-associated markers were also measured. The results indicated that extracellular nanovesicles derived from ADSCs increased the migration and proliferation of NP cells and inhibited inflammatory activity, suggesting their utility for the treatment of intervertebral disc degeneration.

Association between Gene Polymorphisms of T Cell Immunoglobulin Domain and Mucin Domain-3 and Risk of Asthma: A Systematic Review and Meta-analysis.

Previous studies have reported that T cell immunoglobulin domain and mucin domain-3 (TIM-3) 574T>G and 1516G>T are associated with the risk of asthma. However, the results are inconsistent due to the small sample size and varied age in studies. We performed this meta-analysis to systematically evaluated the effect of TIM-3 574T>G and 1516G>T genetic polymorphisms on asthma. Eligible articles that reported an association between TIM-3 574T>G and 1516G>T genetic polymorphisms and asthma were searched in PubMed, Medline, EMBASE, Google Scholar, and China National Knowledge Infrastructure up to April 2020. Random or fixed-effects models were used to calculate the summary of odds ratios (ORs) and 95% confidence intervals (CIs) to detect any potential associations between TIM-3 genetic polymorphisms and asthma. Subgroup and sensitivity analyses were performed to assess the potential sources of heterogeneity and the robustness of the pooled estimation. Publication bias was analyzed using the Egger test. A total of 11 case-control studies including 2077 asthma patients and 2122 control subjects were finally analyzed (published data form 2004-2018). The pooled results indicated that TIM-3 574T>G genetic polymorphisms were significantly associated with an increased risk of asthma under the dominant model (GG vs. GT +TT: ORs=2.26, 95% CI 1.09-4.69) and allele model (G vs T: ORs=2.60, 95% CI 1.20-5.64). However, no significant associations between TIM-3 1516G>T genetic polymorphisms with asthma in any model was found. No evidence of publication bias was observed.  Our study indicates that TIM-3 574T>G genetic polymorphisms were associated with increased risk of asthma and the TIM-3 1516G>T genetic polymorphisms may not be correlated with asthma.

The efficacy and safety of multiple-dose intravenous tranexamic acid in reducing perioperative blood loss in patients with thoracolumbar burst fracture.

OBJECTIVE: To evaluate the efficacy and safety of tranexamic acid (TXA) for single-segment thoracolumbar burst fracture without neurologic injury underwent pedicle screw fixation via Wiltse approach. PATIENTS AND METHODS: We identified 264 patients with single-segment thoracolumbar burst fracture without neurologic injury underwent pedicle screw fixation via Wiltse approach (January 2016-June 2019) at a single center. The cohort was separated into three groups. Group A received 20 mg/kg TXA at 5 min before skin incision and 16 h after first dose; Group B received 20 mg/kg TXA at 5 min before skin incision; Group C received NS at each same time point. The outcomes were evaluated by hidden blood loss (HBL), total blood loss (TBL), intraoperative blood loss (IBL), transfusion rate, maximum hemoglobin (Hb) drop, prethrombotic state molecular markers, liver and renal function, coagulation function, inflammatory factor and adverse events. RESULTS: The HBL, TBL and maximum Hb drop were significantly lower in Group A than those of Group B and Group C, while the difference between Group B and Group C was statistically significant. The IBL was significantly lower in Group A and Group B than that of Group C. However, there was no significantly difference among the three groups in live and renal function, coagulation function, prethrombotic state molecular markers, transfusion rate and complications during the perioperative period. There was significantly lower level of interleukin-6 (IL-6) in Group A than Group C at the day after surgery, and lower level of C-reactive protein (CRP) at the third day after surgery. CONCLUSIONS: Intravenous TXA used in the treatment of thoracolumbar burst fracture underwent pedicle screw fixation via Wiltse approach is effective and safe in decreasing perioperative blood loss. The two-dose TXA regimen can further reduce blood loss and alleviate post-operative inflammation response, without affecting prethrombotic state molecular marks and without increasing the risk of complications.

Outcome Evaluation of Zero-Profile Device Used for Single-Level Anterior Cervical Discectomy and Fusion with Osteoporosis Compared without Osteoporosis: A Minimum Three-Year Follow-Up Study.

OBJECTIVE: We compared the mid-term efficacy and safety of anterior cervical discectomy and fusion (ACDF) using a Zero-Profile device for cervical degenerative disc disease (CDDD) with and without osteoporosis. METHODS: We performed a retrospective study of elderly patients with CDDD treated by single-level ACDF with a Zero-Profile device. The patients were divided into group A (osteoporosis) and group B (no osteoporosis) according to the bone mineral density. The clinical outcomes (Japanese Orthopaedic Association, neck disability index, visual analog scale, and short-form 36 scores), radiological outcomes (cervical lordosis and fusion rate), and complications were reviewed at each follow-up examination. RESULTS: All procedures were successfully performed in all patients. The Japanese Orthopaedic Association, neck disability index, visual analog scale, and short-form 36 scores and cervical lordosis were significantly improved postoperatively in both groups (P < 0.05). However, no significant difference was found between the 2 groups at each follow-up point (P > 0.05). No significant difference was found in the fusion rate at 3 months postoperatively (group A, 88.9%; group B, 90.0%), dysphagia rate at 1 month postoperatively (group A, 11.1%; group B, 15.0%), or cage subsidence rate at the final follow-up visit (group A, 11.1%; group B, 10.0%; P > 0.05). All patients achieved solid fusion, and no patient had dysphagia at the final follow-up examination. CONCLUSIONS: ACDF with the Zero-Profile device can be used as an effective and reliable treatment for single-level CDDD with osteoporosis.

Associations between VDR Gene Polymorphisms and Osteoporosis Risk and Bone Mineral Density in Postmenopausal Women: A systematic review and Meta-Analysis.

Results on the relationships between vitamin D receptor (VDR) gene polymorphisms and postmenopausal osteoporosis (PMOP) susceptibility and bone mineral density (BMD) are conflicting. The aim of the study is to identify more eligible studies that calculated pooled OR and WMD with 95% CI to assess their associations. Overall, there were significant correlations between VDR ApaI, VDR FokI and PMOP susceptibility. Subgroup analysis showed that VDR ApaI polymorphism significantly decreased the osteoporosis risk in Caucasian postmenopausal women. In Asian populations, VDR BsmI and VDR FokI were associated with an increased risk of PMOP. As to the associations between VDR polymorphisms and BMD, Caucasian PMOP women carrying the ApaI aa genotype were at risk of high BMD in femoral neck, and low femoral neck BMD was observed in Caucasian PMOP women with FokI Ff genotype. PMOP women with the Cdx2 GA genotype had a lower lumbar spine BMD in overall and Caucasian populations compared with PMOP women with GG genotype. Different VDR gene polymorphisms have different impacts on PMOP risk and BMD.

Incidence and risk factors for postoperative shoulder imbalance in scoliosis: a systematic review and meta-analysis.

PURPOSE: This is the first systematic review and meta-analysis to detect the incidence and risk factors for postoperative shoulder imbalance (PSI) in scoliosis. METHODS: A systematic online search was conducted to identify eligible studies. ES, OR and WMD with 95% CI were used to assess the incidence and risk factors associated with PSI. RESULTS: Twenty-six studies were recruited. The pooled incidence of PSI was 25% (95% CI 20-31%). The incidence in Lenke 1 AIS, Lenke 2 AIS, Lenke 5 AIS and mixed AIS was 20% (9-31%), 26% (15-37%), 31% (17-45%) and 27% (19-35%), respectively. Using RSH ≥10 mm as the criterion of PSI, we found that preoperative LC, postoperative RSH, correction rate of MTC at follow-up were primary risk factors for PSI at follow-up. In the analysis of using RSH ≥20 mm as the criterion of PSI, our results showed that Risser sign, postoperative RSH, correction rate of PTC at follow-up, and LC at follow-up were contributing to PSI. Besides, scoliosis patients with PSI were more likely to suffer from adding-on. CONCLUSIONS: The pooled incidence of PSI in scoliosis was 25%. Risser sign, preoperative LC, postoperative RSH, correction rate of PTC at follow-up, correction rate of MTC at follow-up, and LC at follow-up were risk factors for PSI in patients with scoliosis. Adding-on might be a compensatory mechanism for PSI. It is recommended that (1) sufficient correction of PTC and moderate correction of MTC and LC in the operation should be performed; (2) PSI should be prevented not only for the patients' postoperative appearance, but also for preventing the adding-on phenomenon.

Treating osteoporotic vertebral compression fractures with intraosseous vacuum phenomena using high-viscosity bone cement via bilateral percutaneous vertebroplasty.

Osteoporotic vertebral compression fractures with intraosseous vacuum phenomena could cause persistent back pains in patients, even after receiving conservative treatment. The aim of this study was to evaluate the efficacy of using high-viscosity bone cement via bilateral percutaneous vertebroplasty in treating patients who have osteoporotic vertebral compression fractures with intraosseous vacuum phenomena.Twenty osteoporotic vertebral compression fracture patients with intraosseous vacuum phenomena, who received at least 2 months of conservative treatment, were further treated by injecting high-viscosity bone cement via bilateral percutaneous vertebroplasty due to failure of conservative treatment. Treatment efficacy was evaluated by determining the anterior vertebral compression rates, visual analog scale (VAS) scores, and Oswestry disability index (ODI) scores at 1 day before the operation, on the first day of postoperation, at 1-month postoperation, and at 1-year postoperation.Three of 20 patients had asymptomatic bone cement leakage when treated via percutaneous vertebroplasty; however, no serious complications related to these treatments were observed during the 1-year follow-up period. A statistically significant improvement on the anterior vertebral compression rates, VAS scores, and ODI scores were achieved after percutaneous vertebroplasty. However, differences in the anterior vertebral compression rate, VAS score, and ODI score in the different time points during the 1-year follow-up period was not statistically significant (P > 0.05).Within the limitations of this study, the injection of high-viscosity bone cement via bilateral percutaneous vertebroplasty for patients who have osteoporotic vertebral compression fractures with intraosseous vacuum phenomena significantly relieved their back pains and improved their daily life activities shortly after the operation, thereby improving their life quality. In this study, the use of high-viscosity bone cement reduced the leakage rate and contributed to their successful treatment, as observed in patients during the 1-year follow-up period.

Outcome Evaluation of Zero-Profile Implant Compared with an Anterior Plate and Cage Used in Anterior Cervical Discectomy and Fusion: A Two-Year Follow-Up Study.

AIM: To compare the clinical outcome and complications between Zero-P implant and cage with anterior plate in patients undergoing anterior cervical discectomy and fusion (ACDF). MATERIAL AND METHODS: 50 patients underwent ACDF operation of which 23 patients had Zero-P implanted and 27 had cage and plate implanted. Preoperative and Post-operative clinical evaluation included Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI) score and Short form 36 (SF-36). Incidences of dysphagia-related symptoms were recorded. Plain radiographs were performed 2 days postoperatively and at follow-up to evaluate cervical prevertebral soft tissue, sagittal alignment, fusion rate and implant failure. RESULTS: In both groups, the JOA and SF-36 scores significantly increased, cervical sagittal alignment significantly corrected and the NDI score dropped compared to the preoperative at follow-up. All patients achieved solid fusion and no implant displacement was observed. The thickness of the prevertebral soft tissue at 2 days and 3 months postoperatively was lower in the Zero-P group. The incidence of dysphagia in the Zero-P group was significantly lower and the duration was much shorter. CONCLUSION: Zero-P used in ACDF could lead to similar clinical and radiographical outcomes compared with cage and plate, but with lower incidence and shorter duration of dysphagia.

Unipedicular versus bipedicular percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a prospective randomized study.

BACKGROUND: Percutaneous vertebroplasty (PVP) typically involves conventional lower-viscosity cement injection via bipedicular approach. Limited evidence is available comparing the clinical outcomes and complications in treating osteoporotic vertebral compression fractures (OVCFs) with PVP using high-viscosity cement through unipedicular or bipedicular approach. METHODS AND DESIGN: Fifty patients with OVCFs were randomly allocated into two groups adopting unipedicular or bipedicular PVP. The efficacy of unipedicular and bipedicular PVP was assessed by comparing operation time, X-ray exposure time, incidence of complications, vertebral height restoration, and improvement of the visual analogue scale (VAS), Oswestry disability index (ODI) and Short Form-36 (SF-36) General Health Survey scores. RESULTS: The mean operative and exposure time to X-rays in the unipedicular PVP group was less than that of the bipedicular group (p < 0.05). No statistically significant differences were observed in the VAS score, ODI score, SF-36 score, cement leakage rate or vertebral height restoration between the two groups (p > 0.05). CONCLUSION: Unipedicular and bipedicular PVP are safe and effective treatments for OVCF. Compared with bipedicular PVP, unipedicular PVP entails a shorter surgical time and lower X-ray irradiation.

A comparison of high viscosity bone cement and low viscosity bone cement vertebroplasty for severe osteoporotic vertebral compression fractures.

OBJECTIVE: To compare the clinical outcome and complications of high viscosity and low viscosity poly-methyl methacrylate bone cement PVP for severe OVCFs. METHODS: From December 2010 to December 2012, 32 patients with severe OVCFs were randomly assigned to either group H using high viscosity cement (n=14) or group L using low viscosity cement (n=18). The clinical outcomes were assessed by the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Short Form-36 General Health Survey (SF-36), kyphosis Cobb's angle, vertebral height, and complications. RESULTS: Significant improvement in the VAS, ODI, SF-36 scores, kyphosis Cobb's angle, and vertebral height were noted in both the groups, and there were no significant differences between the two groups. Cement leakage was seen less in group H. Postoperative assessment using computed tomography identified cement leakage in 5 of 17 (29.4%) vertebrae in group H and in 15 of 22 (68.2%) vertebrae in group L (P=0.025). CONCLUSIONS: The PVP using high viscosity bone cement can provide the same clinical outcome and fewer complications compared with PVP using low viscosity bone cement.

Calcium pentosan polysulfate and sodium pentosan polysulfate may be used to treat intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is a major health problem world-wide, and several spinal disorders are closely associated with it. Although people have invested a great deal of time and effort, how to prevent and reverse the IDD for the researchers is still a difficult and hot issue. Intervertebral disc belongs to cartilage tissue, and IDD also is the cartilage degeneration disease. A large quantity of studies have shown that Calcium pentosan polysulfate (CaPPS) and sodium pentosan polysulfate (NaPPS) possess chondroprotective activities and play an important role in maintaining cartilage integrity. We reasonably hypothesize that NaPPS and CaPPS may be used to treat IDD. The possible mechanism may include that: (1) the significant effects of NaPPS and CaPPS in improving capillary blood flow could maintain nutritional supply to intervertebral disc, and preserve intervertebral disc tissue against degeneration; (2) CaPPS and NaPPS preserve cartilage integrity, proteoglycan synthesis, and improve cartilage biomechanical properties; (3) as the multifaceted exosite inhibitors of proteinases NaPPS and CaPPS strongly impede the activity and production of proteinases; (4) promotion of the balance between proteinases and TIMPs also may be involved in treating IDD; (5) NaPPS and CaPPS exhibit potent anti-inflammatory effects, and then reduce inflammation-induced IDD. If the hypothesis were conformed, the symptoms caused by IDD and its related diseases would be a corresponding alleviation or even disappearance, which could greatly alleviate the suffering of patients from disc degeneration diseases. Certainly, many roles of CaPPS and NaPPS, such as effectiveness, safety and side effects, need to be tested, and further works such as animal model and clinical trial, need to be done to prove this hypothesis.

Modic type III lesions and Schmorl's nodes are the same pathological changes?

INTRODUCTION: Degenerative disc disease (DDD) is a major health problem worldwide. Both Modic lesions and Schmorl's nodes are considered to correlate with DDD such as low back pain. Modic lesions are the changes of degenerative vertebral endplate and adjacent bone marrow observed on magnetic resonance imaging and are divided into three types. Modic type III lesions are thought to represent extensive subchondral bone sclerosis within the bone marrow of adjacent endplate. The pathological performance of Schmorl's nodes is cystic lesions around indistinct sclerotic margins and beneath the cartilaginous endplate. Coincidently, there are many similarities between Modic type III lesions and Schmorl's nodes including pathological appearances, pathogenetic location and related diseases. HYPOTHESIS: We hypothesize that Modic type III lesions and Schmorl's nodes are the same pathological changes, and Modic type III lesions may be the quiescent or incipient pathology phrase of Schmorl's nodes. The clinical symptoms of DDD are also accompanied by emergence of these pathological changes. TESTING: A longitudinal study could be used to test this hypothesis. We could measure and analyze whether Modic type III lesions have increased in size or evolved into Schmorl's nodes as time goes on. SIGNIFICANCE: This hypothesis explains the possible pathologic process of Modic type III lesions and Schmorl's nodes. If the hypothesis were conformed, Modic type III lesions and Schmorl's nodes will be rediscovered, which provides the new basis for the clinical treatment of DDD. In additions, this hypothesis also has crucial significances for the classification of Modic lesions.

[Simulation model on the formation of greenhouse sweet pepper leaf area index].

Leaf area index (LAI) is one of the most important crop parameters in photosynthesis-driving crop growth simulation model and canopy evapotranspiration simulation model, while air temperature and radiation are the important climate factors affecting crop leaf growth. In this paper, experiments with different sweet pepper (Capsicum annuum L.) cultivars and sowing dates were conducted in greenhouse to quantitatively analyze the relationships of the number of unfolding leaves per plant, the number of old leaves removed per plant, and the length of each leaf with air temperature and radiation. Based on these quantitative relationships, a leaf area simulation model for greenhouse sweet pepper was developed, and the independent experimental data were used to validate the model. The results showed that the number of unfolding leaves per plant was a positive exponential function of the product of thermal effectiveness and PAR (TEP) accumulated after emergence, and the length of each leaf was a negative exponential function of the TEP accumulated after emergence. The coefficient of determination (R2) and the root mean squared error (RMSE) between simulated and measured leaf number, leaf length, and LAI were 0.94, 0.89, and 0.93, and 3.4, 2.15, and 0.15, respectively. The model could use air temperature, radiation, planting density, and emergence date to satisfactorily predict the LAI of greenhouse sweet pepper, and supply required LAI information for the sweet pepper growth and canopy evapotranspiration simulation models.