Phase Structure, Bond Features, and Microwave Dielectric Characteristics of Ruddlesden-Popper Type Sr2TiO4 Ceramics.

This work studied the phase constitution, bond characteristics, and microwave dielectric performances of Sr2TiO4 ceramics. Based on XRD and Rietveld refinement analysis, pure tetragonal Ruddlesden-Popper type Sr2TiO4 ceramic is synthesized at 1425~1525 °C. Meanwhile, the microstructure is dense and without porosity, indicating its high sinterability and densification. Great microwave dielectric performances can be obtained, namely an εr value of 39.41, and a Q × f value of 93,120 GHz, when sintered at 1475 °C. Under ideal sintering conditions, the extrinsic factors are minimized and can be ignored. Thus, the intrinsic factors are considered crucial in determining microwave dielectric performances. Based on the P-V-L complex chemical bond theory calculation, the largest bond ionicity, and proportions to the bond susceptibility from Sr-O bonds suggest that Sr-O bonds mainly determine the dielectric polarizability. However, the Ti-O bonds show lattice energy about three times larger than Sr-O bonds, emphasizing that the structural stability of Sr2TiO4 ceramics is dominated by Ti-O bonds, and the Ti-O bonds are vital in determining the intrinsic dielectric loss. The thermal expansion coefficient value of the Sr2TiO4 structure is also mainly decided by Ti-O bonds.

Micro/Mesoporous Fe3O4/Fe-Phthalocyanine Microspheres and Effects of Their Surface Morphology on the Crystallization and Properties of Poly(Arylene Ether Nitrile) Composites.

The surface morphology of nanoparticles significantly affects the final properties and interfacial characteristics of their composites. Thus, investigations on the surface morphology of the nanoparticles is essential to fabricate improved nanoparticle-reinforced composites. Fe3O4/Fe-phthalocyanine (FePc) hybrid microspheres with micro/mesoporous structures were prepared via a solvothermal process and solvent etching method. The surface morphology and compositional distribution were respectively investigated using a scanning electron microscope (SEM) and a transmission electron microscope (TEM) to rule out that FePc monomers have been blended with Fe3O4 to form Fe3O4/FePc hybrid microspheres without serious agglomeration. The surface roughness of Fe3O4/FePc microspheres was investigated by the scanning probe microscope (SPM), and confirmed by the adsorption and desorption isotherms of N2. The effects of the various surface morphologies on the crystallization behavior of crystallizable poly(arylene ether nitrile) (c-PEN) were first employed to confirm the surface characteristics of the resulted microspheres. Results indicated that the etched Fe3O4/FePc microspheres would improve the crystallization degree of c-PEN, due to their much more micro/mesoporous structures than that of original Fe3O4/FePc. Then, Fe3O4/FePc hybrid microspheres reinforced PEN composite films were prepared and their interfacial compatibility was monitored using an SEM. Excellent thermal stability and improved mechanical properties were obtained by combining the etched Fe3O4/FePc and PEN matrix. The excellent surface properties and micro/mesoporous structures make the novel Fe3O4/FePc an excellent candidate of organic/inorganic hybrid fillers and micro/mesoporous materials.

RETRACTED: Abduction external rotation position in magnetic resonance arthrography for the diagnosis of rotator cuff tears.

OBJECTIVE: This article aims at evaluating the effectiveness of abduction and external rotation (ABER) position used in magnetic resonance (MR) arthrography for diagnosing rotator cuff tears. METHODS: A retrospective analysis was performed using 183 MR arthrography images of shoulder joint. Each patient was either examined in a neutral position or ABER position. Then the imaging results were compared with those diagnostic results obtained from shoulder arthroscopy. Also the specificity, sensitivity, negative predictive value, positive predictive value, and accuracy of MR arthrography in the two positions described above were evaluated. RESULTS: A total of 64 patients were diagnosed with rotator cuff tears using arthroscopy and the diagnostic results include 16 complete rotator cuff tears and 48 partial tears; 47 supraspinatus tendon tears and 17 posterosuperior cuff tears; 22 delamination tears and 26 tears complicated with anteroinferior labrum-ligament complex injuries. The differences in specificity, sensitivity, negative predictive value, positive predictive value and accuracy between neutral position and ABER position using MR arthrography were not statistically significant (all P > 0.05). For diagnosing posterosuperior cuff tears, the sensitivity of ABER position was significantly higher than that of the neutral position (94.12% vs. 64.71%, P = 0.034). For diagnosing delamination tears, the sensitivity and negative predictive value of ABER position were significantly higher than those of the neutral position (P = 0.009 and P = 0.036 respectively). For diagnosing rotator cuff tears complicated with anteroinferior labrum-ligament complex injuries, the sensitivity of ABER position was statistically higher than that of the neutral position (96.15% vs. 73.08%, P = 0.021). CONCLUSION: This study suggests that MR arthrography in ABER position is a superior tool for diagnosing certain types of rotator cuff tears. Apart from that, MR arthrography in ABER position improved the detection rate of posterosuperior cuff tears, delamination tears and rotator cuff tears complicated with anteroinferior labrum-ligament complex injuries.

Analysis of 3-dimensional finite element after reconstruction of impaired ankle deltoid ligament.

We compared four repair techniques for impaired ankle ligament deltoideum, namely Wiltberger, Deland, Kitaoka and Hintermann using a 3-dimensional finite element. We built an ankle ligament deltoideum model, including six pieces of bone structures, gristles and main ligaments around the ankle. After testing the model, we built an impaired ligament deltoideum model plus four reconstruction models. Subsequently, different levels of force on ankles with different flexion were imposed and ankle biomechanics were compared. In the course of bending, from plantar flexion 20° to back flexion 20°, the extortion of talus decreased while the eversion increased. Four reconstruction models failed to bring back the impaired ankle to normal, with an obvious increase of extortion and eversion. The Kitaoka technique was useful to reduce the extortion angle in a consequential manner. Compared with the other three techniques, the Kitaoka technique produced better results for extortion angle and the difference was statistically significant. However, in case of eversion, there was no significant difference among the four techniques (P>0.05). Lateral ligament's stress in all the four models was different from the normal one. When the ankle was imposed with extortion moment of force, stress of anterior talofibular ligament with the Kitaoka reconstruction method was close to that of the complete deltoid ligament. When ankle was imposed with eversion moment of force, stress of anterior talofibular ligament with Kitaoka and Deland reconstruction methods were close to that of the complete deltoid ligament. We concluded that Kitaoka and Deland tendon reconstruction technique could recover impaired ankle deltoid ligament and re-established its normal biomechanics characteristics.

The comparative risk of developing postoperative complications in patients with distal radius fractures following different treatment modalities.

In this study, we performed a network meta-analysis to compare the outcomes of seven most common surgical procedures to fix DRF, including bridging external fixation, non-bridging external fixation, K-wire fixation, plaster fixation, dorsal plating, volar plating, and dorsal and volar plating. Published studies were retrieved through PubMed, Embase and Cochrane Library databases. The database search terms used were the following keywords and MeSH terms: DRF, bridging external fixation, non-bridging external fixation, K-wire fixation, plaster fixation, dorsal plating, volar plating, and dorsal and volar plating. The network meta-analysis was performed to rank the probabilities of postoperative complication risks for the seven surgical modalities in DRF patients. This network meta-analysis included data obtained from a total of 19 RCTs. Our results revealed that compared to DRF patients treated with bridging external fixation, marked differences in pin-track infection (PTI) rate were found in patients treated with plaster fixation, volar plating, and dorsal and volar plating. Cluster analysis showed that plaster fixation is associated with the lowest probability of postoperative complication in DRF patients. Plaster fixation is associated with the lowest risk for postoperative complications in DRF patients, when compared to six other common DRF surgical methods examined.

Involvement of Notch1/Hes signaling pathway in ankylosing spondylitis.

We aimed to investigate the role of Notch1/Hes signaling pathway in the pathogenesis of abnormal ossification of hip ligament in patients with ankylosing spondylitis (AS). 22 AS patients scheduled for artificial hip arthroplasty were randomly chosen as AS group. As controls, we used 4 patients diagnosed with transcervical fracture who underwent hip replacement surgery. Notch1 and Hes mRNA expressions were detected by real-time fluorescent quantitative polymerase chain reaction (RFQ-PCR). Immunohistochemistry (IHC) was used to detect Notch1 and Hes protein expression. Correlation analyses of Notch-l and Hes with AS-related clinical factors were conducted with spearman's correlation analysis and partial correlation analysis. RFQ-PCR results showed significant differences in Notch1 and Hes mRNA expressions between AS group and the control group (all P<0.05). IHC analysis further indicated positive nuclear signals of Notch1 and Hes protein, indicating functional activation of the Notch1 and Hes pathways. Semi-quantitative IHC showed a higher Notch1 and Hes expression levels in AS group compared to the control group (all P<0.05). Correlation analysis suggested that Hes protein expression was positively associated with the clinical course of the disease in AS patients. In conclusion, Notch1 and Hes overexpression was clearly detected in hip joint ligaments of AS patients, Hes protein expression was associated with the clinical course of AS. Taken together, we suggest that signaling pathways mediated by Notch1-Hes may contribute to ligament ossification of hip joints in AS patients.

Role of growth differentiation factor-5 and bone morphogenetic protein type II receptor in the development of lumbar intervertebral disc degeneration.

The present study was designed to evaluate the role of growth differentiation factor-5 (GDF-5) and bone morphogenetic protein type II receptor (BMPR-II) in the development of lumbar intervertebral disc degeneration (IDD). A total of 24 patients with lumbar IDD (experiment group) and 6 patients with lumbar vertebral fracture (control group) were enrolled in the study. Tissue samples of IVD from the experiment group and control group were obtained during lumbar fusion operation, respectively. Fixation and decalcification of IVD tissue were performed, and then HE staining was carried out to observe the morphological changes of the lumbar IVD tissues. The expression of GDF-5 and BMPRII in human lumbar IVD was detected by immunohistochemical staining. HE staining results showed that non- and minimal degeneration was found in 11 cases (score range, 0-3), moderate degeneration in 12 cases (score range, 4-8), and severe degeneration in 7 cases (score range, 9-12). According to the immunohistochemical results, the positive expression rates of GDF-5 and BMPRII in NP were higher than those in AF of the non- and minimal degeneration group, moderate degeneration group and severe degeneration group (all P < 0.05). However, no significant difference in GDF-5 or BMPRII positive expression was observed among the normal, non- and minimal, moderate and severe degeneration groups in neither NP area nor AF area (all P > 0.05). In conclusion, our results showed that GDF-5 and BMPRII expressed both in normal and degenerated IVD tissues, and GDF-5 might have an inhibition effect on degenerated lumbar IVD, suggesting that gene therapy may be a useful approach in producing physiological effects during early- and late-phase of lumbar IDD.