Polyurea-Functionalized Multiwalled Carbon Nanotubes

An in situ polycondensation approach was applied to functionalize multiwalled carbon nanotubes (MWNTs), resulting in various linear or hyperbranched polycondensed polymers [e.g., polyureas, polyurethanes, and poly(urea-urethane)-bonded carbon nanotubes]. The quantity of the grafted polymer can be easily controlled by the feed ratio of monomers. As a typical example, the polyurea-functionalized MWNTs were measured and characterized in detail. The oxidized MWNTs (MWNT-COOH) were converted into acyl chloride-functionalized MWNTs (MWNT-COCl) by reaction with neat thionyl chloride (SOCl2). MWNT-COCl was reacted with excess 1,6-diaminohexane, affording amino-functionalized MWNTs (MWNT-NH2). In the presence of MWNT-NH2, the polyurea was covalently coated onto the surfaces of the nanotube by in situ polycondensation of diisocyanate [e.g., 4,4‘-methylenebis(phenylisocyanate)] and 1,6-diaminohexane, followed by the removal of free polymer via repeated filtering and solvent washing. The coated polyurea content can be controlled to some extent by adjusting the feed ratio of the isocyanato and amino groups. The structure and morphology of the resulting nanocomposites were characterized by FTIR, NMR, Raman, confocal Raman, TEM, EDS, and SEM measurements. The polyurea-coated MWNTs showed interesting self-assembled flat- or flowerlike morphologies in the solid state. The signals corresponding to that of the D and G bands of the carbon nanotubes were strongly attenuated after polyurea was chemically tethered to the MWNT surfaces. Comparative experiments showed that the grafted polymer species and structures have a strong effect on the Raman signals of polymer-functionalized MWNTs

Fatigue Property and Cytocompatibility of a Biomedical Co–Cr–Mo Alloy Subjected to a High Pressure Torsion and a Subsequent Short Time Annealing

In the present study, we evaluated the effects of high pressure torsion (HPT) and subsequent short time annealing processing on fatigue properties and cytocompatibility of the biomedical Co–Cr–Mo alloy (CCM). Before processing, CCM was solution treated (CCMST) to achieve a microstructure composed of coarse single γ-phase equiaxed grains with no internal strain. Through HPT processing, an inhomogeneous microstructure containing both micro- and nano-scaled grains is obtained in CCM specimens, which were named as CCMHPT, accompanied by high internal strain and extensive ε martensite. Following a subsequent short time annealing, a uniform single γ-phase ultrafine-grained microstructure with small local strain fields dispersed forms in CCM specimens, which were named as CCMHPTA. This microstructure change improves fatigue strength in CCMHPT, and further in CCMHPTA, because of the enhanced crack initiation and/or propagation resistance. For cytocompatibility evaluation, the cells cultured on CCMST show an immobilization tendency, while those cultured on CCMHPT exhibit a locomotion tendency. The cells cultured on CCMHPTA have an intermediate pattern. Compared with CCMST, much larger numbers of cells are proliferated in both CCMHPT and CCMHPTA. All these results demonstrate that the CCMHPTA offers an improved fatigue property and a good cytocompatibility. Therefore, it is promising for use in biomedical applications

DNA Checkpoint and Repair Factors Are Nuclear Sensors for Intracellular Organelle Stresses-Inflammations and Cancers Can Have High Genomic Risks.

Under inflammatory conditions, inflammatory cells release reactive oxygen species (ROS) and reactive nitrogen species (RNS) which cause DNA damage. If not appropriately repaired, DNA damage leads to gene mutations and genomic instability. DNA damage checkpoint factors (DDCF) and DNA damage repair factors (DDRF) play a vital role in maintaining genomic integrity. However, how DDCFs and DDRFs are modulated under physiological and pathological conditions are not fully known. We took an experimental database analysis to determine the expression of 26 DNA D

Predictors of Difficult Laryngeal Exposure in Suspension Laryngoscopy: A Systematic Review and Meta-Analysis

Objectives. Considerable research has been focused on independent predictors of difficult laryngeal exposure (DLE) during suspension laryngoscopy. However, previous studies have yielded inconsistent results and conclusions. Consequently, we performed a meta-analysis of the existing literature with the aim of identifying significant parameters for a standardized preoperative DLE prediction system. Methods. We systematically retrieved articles from the PubMed, Embase, Web of Science, China National Knowledge Infrastructure, and Wanfang databases up to October 2022. Data from eligible studies were extracted and analyzed using the R programming language. The effect measures included odds ratios (ORs) with 95% confidence intervals (CIs) for dichotomous variables and mean differences (MDs) with 95% CIs for continuous variables. Results. The search yielded 1,574 studies, of which 18 (involving a total of 2,263 patients) were included. Pooled analysis demonstrated that patients with DLE during microsurgery tended to be male (OR, 1.73; 95% CI, 1.16–2.57); were older (MD, 5.47 years, 95% CI, 2.44–8.51 years); had a higher body mass index (BMI; MD, 1.19 kg/m2; 95% CI, 0.33–2.05 kg/m2); had a greater neck circumference (MD, 2.50 cm; 95% CI, 1.56–3.44 cm); exhibited limited mouth opening (MD, −0.52 cm; 95% CI, −0.88 to −0.15 cm); had limited neck flexibility (MD, −10.05 cm; 95% CI, −14.10 to −6.00 cm); displayed various other anatomical characteristics; and had a high modified Mallampati index (MMI) or test score (OR, 3.37; 95% CI, 2.07–5.48). Conclusion. We conducted a comprehensive and systematic analysis of the factors relevant to DLE. Ultimately, we identified sex, age, BMI, neck circumference, MMI, inter-incisor gap, hyomental distance, thyromental distance, sternomental distance, and flexion-extension angle as factors highly correlated with DLE

A Carbon Nanofilament-Bead Necklace

Carbon nanofilaments with carbon beads grown on their surfaces were successfully synthesized reproducibly by a floating catalyst CVD method. The nanofilaments hosting the pearl-like structures typically show an average diameter of about 60 nm, which mostly consists of low-ordered graphite layers. The beads with diameter range 150−450 nm are composed of hundreds of crumpled and random graphite layers. The mechanism for the formation of these beaded nanofilaments is ascribed to two nucleation processes of the pyrolytic carbon deposition, arising from a temperature gradient between different parts of the reaction chamber. Furthermore, the Raman scattering properties of the beaded nanofilaments have been measured, as well as their confocal Raman G-line images. The Raman spectra reveal that that the trunks of the nanofilaments have better graphitic properties than the beads, which is consistent with the HRTEM analysis. The beaded nanofilaments are expected to have high potential applications in composites, which should exhibit both particle- and fiber-reinforcing functions for the host matrixes

BEARING DEGRADATION STATE IDENTIFICATION OF LCD-HILBERT RELATIVE SPECTRUM ENTROPY

In order to better identification the degradation state of bearing, a degradation state feature extraction method for bearing named LCD-Hilbert relative spectrum entropy is proposed based on relative entropy for characterizing the probability distribution difference among different signals. The analysis results of simulation signal demonstrate the availability and relationality of the proposed LCD-Hilbert relative frequency energy spectrum entropy（LHFE）, relative instantaneous energy spectrum entropy（LHIE） and relative singular spectrum entropy（LHSE） used as degradation feature. The degradation feature vector is composed of the three features. The practical vibration of bearing with inner race fault and outer race fault which in different degradation state are analyzed, and the support vector machine is further used to identification degradation state and the results demonstrate the ability of the proposed method

Simulation of 3D Image Reconstruction in Rigid body Motion

3D image reconstruction under rigid body motion is affected by rigid body motion and visual displacement factors, which leads to low quality of 3D image reconstruction and more noise, in order to improve the quality of 3D image reconstruction of rigid body motion. A 3D image reconstruction technique is proposed based on corner detection and edge contour feature extraction in this paper. Region scanning and point scanning are combined to scan rigid body moving object image. The wavelet denoising method is used to reduce the noise of the 3D image. The edge contour feature of the image is extracted. The sparse edge pixel fusion method is used to decompose the feature of the 3D image under the rigid body motion. The irregular triangulation method is used to extract and reconstruct the information features of the rigid body 3D images. The reconstructed feature points are accurately calibrated with the corner detection method to realize the effective reconstruction of the 3D images. The simulation results show that the method has good quality, high SNR of output image and high registration rate of feature points of image reconstruction, and proposed method has good performance of 3D image reconstruction

How the crowd impacts commercial applications: a user-oriented approach

As crowdsourcing has been applied to a variety of disciplines, e.g. marketing and operationalization, more and more scientists turn their sights to how the crowd innovate software engineering to produce high quality software. However, they mainly focus on the impacts brought by domain experts or experienced developers on developing and managing open source softwares, whereas how softwares are influenced by the ordinary people e.g. end users is seldom discussed and easily omitted. To fill up the research gaps, we investigate into commercial application improvement paradigm with assistance of user crowd. The approach focuses on end users by proposing a workflow loop to form a healthy cycle between them and applications. Especially, the approach propose a suggestion model to encourage users to participate into application runtime adaptation. So far, a prototype is developed to enable the crowd to raise and modify their advices, and our prior work has proven the effectiveness in which applications consider the users' advices to adapt themselves. Copyright 2014 ACM.EI1-