Search

Background: The fracture of bone plate can cause considerable pain for the patient and increase the burden on the public finances. This study aims to explore the failure mechanism of 49 plates retrieved from revision surgery and introduce pure magnesium (Mg) block to improve the biomechanical performance of the plate via decreasing the stiffness and to stimulate the biological response of the plate potentially by the degradation of Mg block. Methods: The morphological analysis and component analysis of the plates were conducted to determine the fracture reason of the plates combining the clinical data. According to the structural feature, the 49 retrieved plates were divided into: traditional plate (TP), asymmetrical plate (AP), reconstructive plate (RP) and central enhancement plate (CEP), and their structure features are normalized in a commercial plate, respectively. The biomechanical performance of the plates was evaluated using a validated femoral finite element model. A block of pure Mg with a thickness of 1 mm, 1.5 mm and 2 mm was also incorporated into the CEP to be assessed. Results: The results indicated that the retrieved plates mainly failed due to fatigue fracture induced by delayed union or nonunion (44/49), and using pure titanium plates in weight-bearing areas increased the risk of fracture compared with Ti alloy plates when the delayed union or nonunion occurred. The TP demonstrated the highest compression resistance and bending resistance, while CEP had the highest rotational resistance. As the thickness of the Mg block was increased, the stress on the plate in compression decreased, but the stress in rotation increased. The plate with a 1.5 mm Mg block demonstrated excellent compression resistance, bending resistance and rotational resistance. Conclusion: Fatigue fracture resulting from the delayed union or nonunion is the primary failure reason of plates in clinic. The incorporation of Mg block into plate improves the biomechanical performance and has the potential to promote bone healing. The plate with a 1.5 mm Mg block may be suitable for use in orthopaedics. The translational potential of this article: This study assessed the failure mechanism of retrieved bone plates and used this data to develop a novel plate incorporating a 1.5 mm block of pure Mg block at the position corresponding to the fracture line. The novel plate exhibited excellent compression resistance, bending resistance and rotational resistance due to the alleviation of stress concentrations. The Mg block has the potential to degrade over time to promote fracture healing and prevents fatigue fracture of plates.

Objective To analyze and summarize the clinical and genetic characteristics of potassium channel gene variation in infant epileptic encephalopathy (EE). Methods and Results A total of 11 infants with EE associated with potassium channel gene variation admitted to Hu'nan Children's Hospital from July 2016 to January 2020 were tested by the next generation sequencing (NGS). The variants and their sources were verified by Sanger sequencing. The clinical phenotype included epilepsy of infancy with migrating focal seizures (EIMFS, 4 cases), Ohtahara's syndrome (OS, 2 cases), infantile spasm (IS, 2 cases) and nonspecific EE (3 cases). There were 8 cases of new genetic variation and 3 cases of genetic variation (all from mothers). The variation types were KCNQ2 gene variation (5 cases), KCNT1 gene variation (4 cases) and KCNB1 gene variation (2 cases). Several antiepileptic seizure medicine (ASM) were used in combination therapy, and some of the infants were assisted with ketogenic diet (3 cases). After a mean follow⁃up of 19 months, 3 cases were completely free of seizures, one case was effective, 7 cases were ineffective, and 11 cases were all left with mental retardation and movement disorders. Conclusions Potassium channel gene variation is a common genetic cause of EE in infants, which can cause different clinical phenotypes. Genetic testing can assist in the etiological diagnosis and provide theoretical basis for precise treatment.

Objective: The purpose of this study was to analyze the feasibility of repairing a ruptured intervertebral disc using a patch secured to the inner surface of the annulus fibrosus (AF). Different material properties and geometries for the patch were evaluated.Methods: Using finite element analysis, this study created a large box-shaped rupture in the posterior-lateral region of the AF and then repaired it with a circular and square inner patch. The elastic modulus of the patches ranged from 1 to 50 MPa to determine the effect on the nucleus pulposus (NP) pressure, vertical displacement, disc bulge, AF stress, segmental range of motion (ROM), patch stress, and suture stress. The results were compared against the intact spine to determine the most suitable shape and properties for the repair patch.Results: The intervertebral height and ROM of the repaired lumbar spine was similar to the intact spine and was independent of the patch material properties and geometry. The patches with a modulus of 2–3 MPa resulted in an NP pressure and AF stresses closest to the healthy disc, and produced minimal contact pressure on the cleft surfaces and minimal stress on the suture and patch of all models. Circular patches caused lower NP pressure, AF stress and patch stress than the square patch, but also caused greater stress on the suture.Conclusion: A circular patch with an elastic modulus of 2–3 MPa secured to the inner region of the ruptured annulus fibrosus was able to immediately close the rupture and maintain an NP pressure and AF stress similar to the intact intervertebral disc. This patch had the lowest risk of complications and produced the greatest restorative effect of all patches simulated in this study.

Recommendation systems alleviate the problem of information overload caused by the rapid increase of data on the Internet.But traditional recommendation systems are not accurate enough due to data sparsity and cold start.Therefore,a novel recommendation algorithm based on knowledge graph and tag-aware (KGTA) is proposed.First,tags of items and users are used to capture low-order and high-order features through knowledge graph representation learning.The semantic information of entities and relationships in two knowledge graphs is embedded into a low-dimension vector space to obtain the unified representation of items and users.Then,deep neural networks and recurrent neural networks combining attention mechanism are respectively utilized to extract the latent features of items and users.Finally,ratings are predicted on the basis of latent features.KGTA not only takes relationship information and semantic information of knowledge graph and tags into consideration,but also learns latent features of items and users through deep structures.Experimental results on MovieLens datasets illustrate that the proposed algorithm performs better in rating prediction and improves the accuracy of recommendation.

Objective: The purpose of this study was to analyze the stability and instrument-related complications associated with fixation of the lumbar spine using the Short-Rod (SR) technique.Methods: Using finite element analysis, this study assessed the stability of a bilateral lumbar fixation system when inserting the pedicle screws at angles of 10°, 15°, and 20° to the endplate in the sagittal plane. Using the most stable construct with a screw angle, the model was then assessed with different rod lengths of 25, 30, 35, and 45 mm. The optimal screw inclination angle and rod length were incorporated into the SR model and compared against traditional parallel screw insertion (pedicle screws in parallel to the endplate, PPS) in terms of the stability and risk of instrument-related complications. The following parameters were evaluated using the validated L4–L5 lumbar finite element model: axial stiffness, range of motion (ROM), stress on the endplate and facet joint, von-Mises stress on the contact surface between the screw and rod (CSSR), and screw displacement.Results: The results showed that the SR model with a 15° screw inclination angle and 35 mm rod length was superior in terms of construct stability and risk of complications. Compared to the PPS model, the SR model had lower stiffness, lower ROM, less screw displacement, and lower stress on the facet cartilage, the CSSR, and screws. However, the SR model also suffered more stress on the endplate in flexion and lateral bending.Conclusion: The SR technique with a 15° screw inclination and 35 mm rod length offers good lumbar stability with a low risk of instrument-related complications.

Estuary river–lake (ERL) complex is critical for the development of ichthyoplankton, which plays an essential role in the breeding, nursing, and recruitment of freshwater fish species. In this study, different ERL sections were selected to investigate the ichthyoplankton assemblage from the Changjiang River estuary to its Hukou section between May 2018 and August 2020. During the study period, fish larvae of 40, 35, 54, and 46 fish species were sampled in the Rugao (RG), Nanjing (NJ) (nearby estuary), Anqing (AQ), and Hukou (HK) (connected river–lake) sections in the Changjiang River, respectively. Results on ichthyoplankton surveys revealed fluctuating assemblage patterns in the different river sections; larval fish species composition presented ecological habitat-dependent characteristics, which supported the importance of ERL complex for ichthyoplankton development. Furthermore, the density of fish larvae was negatively correlated with water transparency but positively correlated with water temperature, the daily rate of water level increase, and runoff in the limitative range. A generalized additive model analysis indicated that the hydrological factors significantly affecting larval fish abundance are water temperature, transparency, the daily rate of water level increase, and runoff (p < 0.05). These results also indicated that river estuaries and river–lake connected complexes are essential for ichthyoplankton recruitment and migration. In combination with the historical record, ichthyoplankton assemblage’s patterns in the Changjiang River lower reaches were preliminarily elucidated, although additional works are needed such as assessing effects on their survival and recruitment.

K2SiF6:Mn4+ phosphor was prepared by wet chemical etching, and the effect of the raw material molar ratio of K/Mn of different materials and different reaction time on the structure and properties of phosphor was studied,the surface of K2SiF6:Mn4+ was coated with SiO2 to improve the thermal stability of K2SiF6:Mn4+ phosphor by sol-gel method. The structure, morphology, excitation spectrum and emission spectrum of phosphor powder were characterized by X-ray diffraction, scanning electron microscope and fluorescence spectrometer. The results show that the change of K/Mn ratio does not change the crystal structure of K2SiF6:Mn4+, the sample has cubic structure. At 460nm excitation, the strongest narrowband emission peak is located at 630nm (2Eg → 4A2). The crystal structure of K2SiF6:Mn4+ phosphor coated with SiO2 has not been changed. The results show that the thermal stability of the K2SiF6:Mn4+ phosphor coated with SiO2 is improved.

Based on Mie scattering and Monte Carlo ray tracing method, the transmission process of light in the remote phosphor film is described and the optical model of red and green laminated phosphor films is constructed. The photochromic properties of the phosphor films were studied by TM-30-15 method proposed by the North American Lighting Association. The investigation discloses that the normalized cross correlation of single-layer phosphor film spectral power distribution between the simulation and experimental results is about 99%, and the deviation of color coordinates is within 0.01. Based on the monochrome phosphor optical model, we establish bicolor optical model of red and green laminated phosphor film layers to form white light and can predict its color performance. The experimental results show that the normalized cross correlation of laminated phosphor film spectral power distribution between the simulation and experiment is about 97%, and the optical model of red and green laminated phosphor film can accurately predict the index Rf and Rg. When the red and green phosphor mass ratio is 0.05:0.5, the simulated color is optimal, Rf reaches 90, and Rg reaches 100, whose corresponding experimental values are Rf=90, Rg=101.

A series of Ce ^3+ /Tb ^3+ singly doped and Ce ^3+ , Tb ^3+ co-doped Ca _3 GdNa(PO _4 ) _3 F phosphors were synthesized via high temperature solid-state reaction in a reductive atmosphere. The crystal, luminescence properties, energy transfer mechanism and thermal stability of the samples were investigated in detail. The Ce ^3+ doped phosphors can be excited in the range from 250 to 330 nm. The Ce ^3+ ,Tb ^3+ co-doped phosphors exhibit characteristic emission of Ce ^3+ and Tb ^3+ simultaneously under the excitation of 301 nm. In addition, the energy transfer efficiency from Ce ^3+ to Tb ^3+ reaches as high as 78.6% when the doping amount of Tb ^3+ is 0.20. The mechanism of energy transfer between Ce ^3+ and Tb ^3+ ions is demonstrated to be a dipole−dipole interaction. The luminescence characteristics show that this phosphor can be a platform for modeling a new phosphor and application in the solid-state lighting field.