Search

Exosomes generated from adipose-derived mesenchymal stem cells (Exos), and in particular hypoxia-pretreated ADSCs (HExos), possess therapeutic properties that promote spinal cord repair following spinal cord injury (SCI). Nevertheless, the regulatory mechanisms through which HExos exert their effects remain unclear. Here, next-generation sequencing (NGS) was utilized to examine abnormal circRNA expression comparing HExos to Exos. Bioinformatics analysis and RNA pulldown assays together with luciferase reporter assays were applied to determine interactions among miRNAs, mRNAs and circRNAs. ELISA and immunofluorescence staining were used to examine inflammatory cytokine levels, apoptosis and ROS deposition in LPS-treated HT-22 cells, respectively. The therapeutic effects of Exos and HExos on a mouse model of SCI were analyzed by immunohistochemistry and immunofluorescence staining. Our findings confirmed that HExos have more significant therapeutic influences on decreasing ROS and inflammatory cytokine levels post-SCI than Exos. NGS revealed that circ-Wdfy3 expression levels were significantly higher in HExos than Exos. Downregulation of circ-Wdfy3 led to a decrease in HExo-induced therapeutic effects on spinal cord repair post-SCI, indicating that circ-Wdfy3 has a critical role in the regulation of HExo-mediated protection against SCI. Our bioinformatics, RNA pulldown and luciferase reporter data demonstrated that GPX4 and miR-423-3p were downstream targets of circ-Wdfy3. GPX4 downregulation or miR-423-3p overexpression reversed the protective effects of circ-Wdfy3 on LPS-treated HT-22 cells. Furthermore, overexpression of circ-Wdfy3 led to an in increase in the Exo-induced therapeutic effects on spinal cord repair post-SCI through the inhibition of ferroptosis. circ-WDfy3-overexpressing Exos promote spinal cord repair post-SCI through mediation of ferroptosis via the miR-138-5p/GPX4 pathway. • circ-WDfy3-overexpressing Exos promote spinal cord repair post-SCI through mediation of ferroptosis via the miR-138-5p/GPX4 pathway. • circ-Wdfy3 role in HExo-mediated spinal cord repairing post-SCI. • Downregulation of circ-Wdfy3 led to a decrease in the therapeutic effects of HExos on spinal cord repair in SCI mice. [ABSTRACT FROM AUTHOR]

This study employed the bobbin tool friction stir welding (BT-FSW) technique to weld 2219 aluminum alloy with 6 mm thickness. The microstructure investigation revealed that the weld nugget zone (WNZ) has a small number of coarse θ phases, whereas the heat-affected zone (HAZ) exhibits colossal amount of θ' phases. The impedance analysis demonstrated that the corrosion resistance of the WNZ is better than that of other zones. Also, the salt spray corrosion test showed that the WNZ has the best corrosion resistance, whereas the base metal (BM) has the worst corrosion resistance. Therefore, the poor corrosion resistance of the BM can be attributed to a high content of the precipitates. • 2219 aluminium alloy was joined using the bobbin tool friction stir welding method. • The corrosion prerformance of BT-FSW joints was investigated using the LEIS method and salt spray corrosion test. • Corrosion attack was galvanic corrosion between the precipitates and matrix. • The relation between corrosion susceptibility and the content of precipitates was revealed. [ABSTRACT FROM AUTHOR]

Little work has been reported directly compared to the tribological behavior of plasma nitrided pure titanium and those coated with TiN coatings. This work prepared the compound layers and coatings with the same thickness on TA2 pure titanium by plasma nitriding and multi-arc ion plating. The tribological behaviors of sliding against ZrO 2 balls under lubricant conditions were investigated using a UMT-5 tribo-tester. The results reveal that nitrided and coating samples showed the friction coefficients (0.11–0.12) were significantly decreased compared to that (~0.33) of the TA2 pure titanium matrix. It was also found that the wear mechanism is different after nitriding or coating, which is caused by the surface phases, chemical composition, and surface roughness under other processes. [ABSTRACT FROM AUTHOR]

Abstract: Needle-like aragonite was synthesized with a reversible solution reaction from limestone without calcinations. Scan Electron Microscope (SEM) and X-ray Diffraction (XRD) were used to characterize the morphology and the crystal structure of aragonite. The synthesis of aragonite whisker involves two steps. At first GCC (Ground Calcium Carbonate) was dissolved in an aqueous solution of magnesium chloride with reflux and air flush. Then CO2 was bubbled into the suspension at a low temperature to produce aragonite whisker. An in-house designed reactor and acid–base titration analysis were used to measure the remaining GCC content in the reaction mixture. A kinetics equation of GCC dissolution was developed, which showed a first-order kinetic feature to magnesium chloride concentration. A reaction rate constant of 0.04234h−1 was obtained. The dissolution rate of GCC in magnesium chloride is much higher than that in the magnesium sulfate solution. Some aragonite whiskers with a length of ca. 20μm and an aspect ratio of 8–12 can be synthesized. [Copyright &y& Elsevier]

To investigate and compare split-hand phenomenon quantified by motor unit number index (MUNIX) between patients with cervical spondylotic amyotrophy (CSA) and those with amyotrophic lateral sclerosis (ALS). MUNIX was performed on abductor pollicis brevis (APB), abductor digiti minimi (ADM) and first dorsal interosseous (FDI) in 46 CSA patients, 39 ALS patients and 41 healthy subjects. Split-hand measurements including split-hand index (SHI = ABP × FDI/ADM), ratio of APB to ADM (AA), ratio of FDI to ADM (FA) were measured by compound muscle action potential (CMAP) and MUNIX. There was a significant difference in both AA and SHI measured by two different methods between ALS and CSA patients (P < 0.05). Receiver operating characteristic (ROC) curve and logistic regression analysis demonstrated good differential diagnostic accuracy for AA, SHI and their combination between ALS and CSA. A larger area under the curve (AUC) was observed in these measurements calculated by MUNIX than those measured by CMAP (AA: 0.885 vs. 0.700, SHI: 0.865 vs. 0.703, Combination: 0.925 vs. 0.750; P < 0.05). Sub-group analysis of ROC curves revealed an AUC of 0.893 for AA MUNIX , 0.801 for SHI MUNIX and 0.896 for their combination in differentiating "clinically possible" ALS (Awaji-Shima criteria) from CSA (P < 0.05). Both AA and SHI measured by two different methods are useful in distinguishing ALS from CSA, and those quantified by MUNIX may be a better differential diagnostic marker to provide an accurate and noninvasive additional test for distinguishing CSA from ALS, even in their early stages. [ABSTRACT FROM AUTHOR]

In this work, electron beam melting (EBM) titanium alloy were strengthened by carrying out a hollow cathodic plasma source nitriding treatment. The EBM-TC4 alloys were nitrided at 500 °C for 1, 3, and 5 h in an NH 3 atmosphere. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy was used to evaluate the microstructure and surface morphology of the samples. The nitrided layers formed on the EBM-TC4 alloy were identified as TiN, Ti 2 N, and nitrogen-stabilized α(N)–Ti phases. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were carried out to evaluate the electrochemical behavior of the samples in Hank's balanced salt solution. The relationship between the corrosion resistance of the nitrided layer and its microstructure was explored. Thus, the improved properties of the nitrided alloys can be attributed to the formation of a Ti–N layer composed of an outermost nanocrystalline/amorphous TiN layer and a crystalline TiN sub-layer on the top of the Ti 2 N crystal layer. The novel Ti–N layer structure with improved corrosion resistance provides broad opportunities for the application of commercial Ti alloys and improving their durability. • HCPSN was used to fabricate a nitrided layer on an EBM-TC4 alloy. • A compound layer composed of an outermost nanocrystalline/amorphous TiN layer and a crystalline TiN sub-layer and on the top of the Ti 2 N crystal layer. • The nitrided layer remarkably improved the corrosion resistance of the EBM-TC4 alloy in Hank's balanced salt solution. • This can be attributed to the formation of a protective multilayer-structured Ti–N layer and its appropriate roughness. [ABSTRACT FROM AUTHOR]

TA15 and TC17 titanium alloys were joined by linear friction welding (LFW) method. The microstructure investigation indicated that the TC17 side welding zone (WZ) was composed of coarse β phases, α phase at grain boundaries and martensite α' phase at the grain interior, while the TA15 side WZ consisted of abundant acicular martensite α' phases and few retained β phases. Electrochemical test result indicated that TA15 base metal (BM) has better corrosion resistance than the TC17 BM. Numerous corrosion pits were formed on the TC17 BM and TC17 side WZ after immersion and salt spray tests. The worse corrosion resistance of the TC17 BM could be attributed to its high content α/β phase boundaries. • TA15 and TC17 titanium alloys were joined by linear friction welding method. • TC17 side welding zone consisted of coarse β phase, α phase and α' phase, while TA15 side welding zone was almost martensite α' phase. • TA15 base metal possessed best corrosion resistance due to lower content of α/β phase boundaries. [ABSTRACT FROM AUTHOR]

Electron beam melting (EBM) is an additive manufacturing technology that allows flexible processing of parts with complex shapes, but the product surface is usually rough and porous, which affects its corrosion resistance. In this study, the plasma nitriding has been conducted on electron beam melted Ti6Al4V titanium alloy. The samples were analyzed using X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscope (HRTEM). The results showed that the plasma nitriding-treated EBM sample (PN-EBM) exhibited better corrosion resistance in natural seawater than the EBM sample due to the generation of a ∼16 μm compound layer, which can effectively prevent the intrusion of harmful ions and enhance the corrosion resistance of the EBM titanium alloy. • Electron beam melted Ti6Al4V titanium alloy was surface strengthened by plasma nitriding. • N-rich modified layer with a nitrogen content of 8∼10 wt% composed of TiN and Ti 2 N phases. • Plasma nitriding significantly improve the corrosion resistance of EMB samples in natural seawater environments. [ABSTRACT FROM AUTHOR]

Objective The kinematic characteristics of Modic changes (MCs) in the lumbar spine have rarely been reported; furthermore, the effect of disc degeneration (DD) on segmental motion has not been considered in analyzing the motion characteristics of MCs. Therefore, this study was designed to evaluate the kinematic characteristics of MCs based on different DD grades. Methods 894 patients with 4470 lumbar segments were reviewed, and those with MCs were selected for segmental motion evaluation. MC type was defined as 0, I, II, and III, and DD grade was classified into 5 groups from grade A to grade E. Segmental angular and translational motion were calculated from X-ray images in positions of flexion and extension, and the absolute values of the differences were recorded. Results MCs were observed in 308 segments from 260 patients. No MC was found in DD grade A, and MC III was not observed in DD grade B. MC I was found to significantly increase angular motion in the DD grade E group, and MC II could enlarge translational motion in the DD grade D group (all P < 0.05); MC III had the lowest segmental motion in both angular and translational motion; There was no statistical difference in angular and translational motion between MC I and II in all DD grade groups (all P > 0.05). Conclusions MC III indicates the final stable phase of segmental motion. MC I might increase angular motion, and MC II would increase certain translational motions in the segments that were believed to be stable. [ABSTRACT FROM AUTHOR]