The retropharyngeal reduction plate for atlantoaxial dislocation: a finite element analysis

Objective: To investigate the biomechanical properties of the retropharyngeal reduction plate by comparing the traditional posterior pedicle screw-rod fixation by finite element analysis.Methods: Two three-dimensional finite element digital models of the retropharyngeal reduction plate and posterior pedicle screw-rod fixation were constructed and validated based on the DICOM (Digital Imaging and Communications in Medicine) data from C1 to C4. The biomechanical finite element analysis values of two internal fixations were measured and calculated under different conditions, including flexion, extension, bending, and rotation.Results: In addition to the backward extension, there was no significant difference in the maximum von Mises stress between the retropharyngeal reduction plate and posterior pedicle screw fixation under other movement conditions. The retropharyngeal reduction plate has a more uniform distribution under different conditions, such as flexion, extension, bending, and rotation. The stress tolerance of the two internal fixations was basically consistent in flexion, extension, left bending, and right bending.Conclusion: The retropharyngeal reduction plate has a relatively good biomechanical stability without obvious stress concentration under different movement conditions. It shows potential as a fixation option for the treatment of atlantoaxial dislocation

Biomechanical evaluation of different posterior fixation techniques for treating thoracolumbar burst fractures of osteoporosis old patients: a finite element analysis

Objective: To investigate the biomechanical characteristics of different posterior fixation techniques in treatment of osteoporotic thoracolumbar burst fractures by finite element analysis.Methods: The Dicom format images of T10-L5 segments were obtained from CT scanning of a volunteer, and transferred to the Geomagic Studio software, which was used to build digital models. L1 osteoporotic burst fracture and different posterior fixation techniques were simulated by SolidWorks software. The data of ROM, the maximum displacement of fixed segment, ROM of fractured L1 vertebrae, the stress on the screws and rods as well as on fractured L1 vertebrae under different movement conditions were collected and analysed by finite element analysis.Results: Among the four groups, the largest ROM of fixed segment, the maximum displacement of fixed segment and ROM of fractured vertebrae occurred in CBT, and the corresponding data was 1.3°, 2.57 mm and 1.37°, respectively. While the smallest ROM of fixed segment, the maximum displacement of fixed segment and ROM of fractured vertebrae was found in LSPS, and the corresponding data was 0.92°, 2.46 mm and 0.89°, respectively. The largest stress of screws was 390.97 Mpa, appeared in CBT, and the largest stress of rods was 84.68 MPa, appeared in LSPS. The stress concentrated at the junction area between the root screws and rods. The maximum stress on fractured vertebrae was 93.25 MPa, appeared in CBT and the minimum stress was 56.68 MPa, appeared in CAPS. And the stress of fractured vertebrae concentrated in the middle and posterior column of the fixed segment, especially in the posterior edge of the superior endplate.Conclusion: In this study, long-segment posterior fixation (LSPF) provided with the greatest stability of fixed segment after fixation, while cortical bone screw fixation (CBT) provided with the smallest stability. Cement-augmented pedicle screw-rod fixation (CAPS) and combined using cortical bone screw and pedicle screw fixation (CBT-PS) provided with the moderate stability. CBT-PS exhibited superiority in resistance of rotational torsion for using multiple connecting rods. CAPS and CBT-PS maybe biomechanically superior options for the surgical treatment of burst TL fractures in osteoporotic patients

CD133 (Prominin) Negative Human Neural Stem Cells Are Clonogenic and Tripotent

CD133 (Prominin) is widely used as a marker for the identification and isolation of neural precursor cells from normal brain or tumor tissue. However, the assumption that CD133 is expressed constitutively in neural precursor cells has not been examined

Kham in the 1950s: Transition of Power in the Peripheries

On October 7th, 1950, the Chinese communists launched the Battle of Chamdo, the eastern border of Tibet. No sooner was Tibet “peacefully liberated,” the Chinese reinforcements arrived. This research focuses on Kham Tibetans during the transition of power in the 1950s. The author argues that Tibetans in the 1950s did not simply fit into the binary categories: pro-Tibet or pro-China. Instead, they were in between, situated in a tangle where hope and fear folded upon individuals. Their responses to the Chinese in the 1950s, in fact, rooted a complex system of national identity and individual pursuit

Preparation of Sugarcane Bagasse/Poly(Acrylic Acid-co-Acrylamide) Hydrogels and their Application

In this work, sugarcane bagasse, being an abundant and renewable resource, was used as a raw material to prepare sugarcane bagasse-g-poly(acrylic acid-co-acrylamide) (SB/P(AA-co-AM)) hydrogels. The hydrogels were prepared by free radical graft copolymerization of SB with AA and AM using N,N-methylene-bis-acrylamide (MBA) as a crosslinker. The optimal synthesis conditions were determined by investigating the water absorbency of the hydrogels. The maximum water absorbency reached 269 g/g in deionized water, and the corresponding copper ions adsorption capacity was 265 mg/g. These grafted hydrogels showed a pH-sensitive swelling behavior. Furthermore, they also exhibited excellent water retention capacity, which reserved 92.7%, 81.7%, and 76.8% for 44 h, and 83.7%, 58.6%, and 47.1% for 116 h at 5 °C, 25 °C, and 35 °C, respectively. FTIR spectroscopy and SEM were used to reveal the chemical structure and the morphology of the hydrogels. SEM/EDS further confirmed the adsorption of the copper(II) on the resulting hydrogels. Therefore, SB/P(AA-co-AM) hydrogels could have promising applications as water retention agents and metal ions adsorbents in water treatment and agricultural industries

Odor Discrimination by Similarity Measures of Abstract Odor Factor Maps from Electronic Noses

The aim of this study is to improve the discrimination performance of electronic noses by introducing a new method for measuring the similarity of the signals obtained from the electronic nose. We constructed abstract odor factor maps (AOFMs) as the characteristic maps of odor samples by decomposition of three-way signal data array of an electronic nose. A similarity measure for two-way data was introduced to evaluate the similarities and differences of AOFMs from different samples. The method was assessed by three types of pipe and powder tobacco samples. Comparisons were made with other techniques based on PCA, SIMCA, PARAFAC and PARAFAC2. The results showed that our method had significant advantages in discriminating odor samples with similar flavors or with high VOCs release

Removal of Heavy Metals from Aqueous Solutions Using Acrylic-modified Sugarcane Bagasse-based Adsorbents: Equilibrium and Kinetic Studies

Recently, more and more attention has been centered on developing cheaper, highly efficient, environmentally friendly adsorbents for the removal of metal ions from industrial effluents. The present work deals with the removal of metal ions from an aqueous solution using a highly efficient, biodegradable adsorbent from hydrogel prepared by the free radical graft polymerization of sugarcane bagasse with acrylic acid and acrylamide using N, N-methylene-bis-acrylamide as a crosslinker. FTIR and SEM/EDX spectroscopies were used to characterize the structure and the morphology of adsorbent before and after the metal ions adsorption. The effects of pH, contact time, and initial concentration of metal ion on the adsorption capacity were studied. The adsorption equilibrium time of Pb2+, Cd2+, and Cu2+ were 60, 90, and 180 min, respectively. The maximum adsorption capacities of Cu2+, Pb2+, and Cd2+ were 268, 700, and 320 mg/g, respectively. The adsorption data were fit to often-used models for adsorption kinetics and isotherms. It was determined that the experimental results were well fitted to the pseudo-second-order equation and Langmuir adsorption isotherms

Pursuing supply chain ecosystem health under environmental turbulence: a supply chain learning approach

Although supply chain ecosystem health (SCE Health) is receiving attention in relation to environmental uncertainty, its conception and measurement are largely undocumented, and how to pursue SCE Health under environmental turbulence is unclear. Supply chain learning (SCL) is an important way to build dynamic capabilities, and whether it can empower the achievement of SCE Health is worthy of investigative study. Therefore, grounded in the dynamic capabilities theory, a survey data-based structural equation modelling (SEM) approach is employed. Based on four experts’ opinions and an in-depth literature review, 47 measurement items (11 for SCL, 28 for SCE Health, and 8 for environmental turbulence) were identified in the questionnaire design. Further, 208 valid questionnaires from the field survey of supply chain management (SCM)-related firms in China were collected and used for SEM analysis. The results show that the internal learning of SCL stimulates its external learning. SCL empowers the pursuit of SCE Health, which is strengthened under higher environmental turbulence. The theoretical framework and results also derive practical insights and support from 11 interviewees of five companies.</p

Adsorption Kinetics and Thermodynamics of Cellulose Dinitrobenzoate Prepared in Ionic Liquid for the Removal Of Creatinine

Creatinine is one of the major toxins in patients suffering from chronic renal failure. In this paper, cellulose dinitrobenzoate, with a degree of substitution (DS) of 0.15, was used as an oral adsorbent for creatinine adsorption. Cellulose dinitrobenzoate was prepared by modification of cellulose with 3,5-dinitrobenzoyl chloride in 1-butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid as a homogenous medium. The effects of contact time, pH, adsorption temperature, and initial concentration of creatinine on the adsorption per unit mass of cellulose dinitrobenzoate were studied, comparatively. Results showed that the maximum adsorption per unit mass for creatinine was 3.88 mg/g. Furthermore, the adsorption process was spontaneous and exothermic. It was determined that the experimental results were well fitted to the pseudo-second-order rate equation and the Freundlich adsorption isotherm. Compared with traditional oral adsorbents, this cellulose-based adsorbent was biocompatible and could remove creatinine from dialysate effectively

Investigation of the Creep Property of Fast-growing Poplar Wood Modified with Low Molecular Weight Resins

Fast-growing poplar wood was modified with low molecular weight urea-formaldehyde resin (UF) at 41.5% concentration or phenol-formaldehyde (PF) at concentrations of 15, 25, and 40%. The physical and mechanical properties were measured, and creep behavior tests were carried out under ambient indoor conditions. The specimens were subjected to 30 and 50% of their maximum bending load. The density, modulus of elasticity, and modulus of rupture of UF-wood increased by 37.16, 45.86, and 28.36%, respectively, and the corresponding increases in 15% PF-specimen were 39.41, 31.80, and 27.74%, respectively. The wood modified with resins exhibited less creep deflection. The relative creep deflections of modified wood were about 0.22, 0.53, 1.22, and 0.32 times those of the untreated specimen at 30% of stress level after 15% PF, 25% PF, 40% PF, and UF were added, respectively. At the lower loading level, the relative creep deflection of the 15% PF specimen was 63.94% that of the 41.5% UF-specimen. Specimens treated with UF at 30 and 50% loading were broken within 120 d and 80 d respectively, whereas the untreated specimen was broken within one month at 50% loading