Mechanical and biological performance of rainbow trout collagen-boron nitride nanocomposite scaffolds for soft tissue engineering

We aim to investigate the potential of collagen extracted from rainbow trout for tissue engineering applications. In this regard, nanocomposite scaffolds based on the extracted collagen reinforced with various concentrations of boron nitride (BN) nanoparticles (0, 3, 6, 9, and 12 wt%) were developed. In addition, the role of various concentrations of BN nanoparticles and two-step cross-linking process on the physical and chemical properties of nanocomposite scaffolds were investigated. Our results demonstrated the isolation of Type I collagen with excellent thermal stability but with some structural and chemical differences compared to other sources. The synergic role of BN nanoparticles and two-step cross-linking process resulted in a noticeable improvement in the mechanical properties of collagen-BN scaffolds. Noticeably, incorporation of 6 wt% BN along with a two-step cross-linking process significantly increased the compressive strength (9.5 times) and elastic modulus (four times) of the collagen scaffold. Besides, nanocomposite scaffolds significantly improved proliferation and spreading of MG-63 cell line, confirming their biocompatibility. The results suggested that the incorporation of BN nanoparticles along with a two-step cross-linking process not only could promote the mechanical and thermal performances of collagen scaffolds, but also enhanced high cell viability, and proliferation supporting their potential in tissue engineering applications.     

Empirical Study of Wavelet Domain Image Joint Statistics and Proposition of an Efficient Correlation Map

This paper presents an empirical study of joint wavelet statistics for textures and other imagery to find an efficient correlation neighborhood. Since there is an established realization that modeling wavelet and other x-let coefficient relationships is crucial to any successful transform domain algorithm (such as Hidden Markov Trees), new works have been devoted to examine these dependencies from different aspects and propose an appropriate model. Because the time and computation complexity involved both in analyzing non-linear dependencies and in solving dependent models may restrict us to consider only a very small subset of contributing neighbors we focus our attention on linear dependencies (correlations) while having a squint on non-linear relations too. In this process, we study a collection of 5000 real images to corroborate our statistical analysis of the joint coefficient behavior and try to find an efficient and at the same time frugal relation map through different statistical means. The statistical observations are then certified by a coefficient significance measure and the competitiveness of the map is substantiated by plugging it into two dependent denoising frameworks.     

New photosensitive poly(amid‐imide)s containing chalcone moiety and hydantoin derivatives in the main chain: Synthesis and characterization

Six new poly(amid‐imide)s containing chalchone and hydantoin moieties in the main chain were synthesized through the polycondensation reaction of 1,3‐bis[4,4′‐bis(trimellityimido)phenyl]‐2‐propenone 6 with six hydantoin derivatives 7a‐f in a medium consisting of triphenyl phosphite, calcium chloride, pyridine, and N‐methyl‐2‐pyrrolidone. The polycondensation reaction produced a series of novel poly(amid‐imide)s 8a‐f in high yields with inherent viscosities between 0.26 and 0.42 dL/g. The resulting polymers were characterized by elemental analysis, viscosity measurements, solubility test, thermo gravimetric analysis (TGA and DTG), FTIR, and UV‐Vis spectroscopy. 1,3‐bis[4,4′‐bis(trimellityimido)phenyl]‐2‐propenone 6 was prepared from a three‐step reaction by using 4‐nitro benzaldehyde 1 and 4‐nitro acetophenone 2 as precursors. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Monitoring inverse‐phase emulsion polymerization using electrical impedance spectroscopy

Inverse‐phase emulsion polymerization (IEP) is a widely used technique for synthesizing polyacrylamide, a product in demand for water treatment and in food industries. Despite its extensive application, challenges exist in controlling and monitoring IEP due to the relatively high polymerization rate and high viscosity of polyacrylamide. We investigated IEP of acrylamide with an industrial solvent, D80, as the oil phase, azobisisobutyronitrile as an oil‐soluble initiator, and a mixture of sorbitan monooleate (Span 80) and poly(oxyethylene sorbitan trioleate) (Tween 85) as emulsifier. Our study showed that electrical impedance spectroscopy (EIS) is an efficient tool for monitoring the progress and characteristics of IEP in real time. The results revealed that the monomer conversion and polymerization rate correlate well with on‐line capacitance measurements using EIS at an appropriate frequency, while changes in conductance correlate well with changes in particle diameter which was validated using an off‐line dynamic light scattering method. © 2014 Society of Chemical Industry     

Highly Uniform Trilayer Molybdenum Disulfide for Wafer‐Scale Device Fabrication

Molybdenum disulfide (MoS₂) is a layered semiconducting material with a tunable bandgap that is promising for the next generation nanoelectronics as a substitute for graphene or silicon. Despite recent progress, the synthesis of high‐quality and highly uniform MoS₂ on a large scale is still a challenge. In this work, a temperature‐dependent synthesis study of large‐area MoS₂ by direct sulfurization of evaporated Mo thin films on SiO₂ is presented. A variety of physical characterization techniques is employed to investigate the structural quality of the material. The film quality is shown to be similar to geological MoS₂, if synthesized at sufficiently high temperatures (1050 °C). In addition, a highly uniform growth of trilayer MoS₂ with an unprecedented uniformity of ±0.07 nm over a large area (> 10 cm²) is achieved. These films are used to fabricate field‐effect transistors following a straightforward wafer‐scale UV lithography process. The intrinsic field‐effect mobility is estimated to be about cm² V^–1 s^–1 and compared to previous studies. These results represent a significant step towards application of MoS₂ in nanoelectronics and sensing.     

Antifungal activity of thyme, summer savory and clove essential oils against Aspergillus flavus in liquid medium and tomato paste

Antifungal activity of essential oils of thyme, summer savory and clove were evaluated in culture medium and tomato paste. Aspergillus flavus were inoculated in Sabouraud Dextrose Broth and tomato paste and then 0, 50, 200, 350 and 500 ppm of essential oils were added to each sample and then kept at 25 ± 0.5 °C for 2 months. Results showed that all essential oils could inhibit the growth of A. flavus and the thyme oil and summer savory, showed the strongest inhibition at 350 ppm and 500 ppm, respectively. Taste panel evaluations were carried out in a tomato ketchup base, and the percent of inhibition of each essential oil in tomato paste was lower than culture medium. Taste panel was carried out and sample with 500 ppm thyme oil was accepted by panelists.     

Microstructure,Defects, and Reliability of Mixed Pb-Free/Sn-Pb Assemblies

The results of an intensive reliability study on Pb-free ball grid array (BGA)/Sn-Pb solder assemblies as well as some lessons learnt dealing with mixed assembly production at Celestica are described in this paper. In the reliability study, four types of Pb-free ball grid array components were assembled on test vehicles using the Sn-Pb eutectic solder and typical Sn-Pb reflow profiles with 205°C to 220°C peak temperatures. Accelerated thermal cycling (ATC) was conducted at 0°C to 100°C. The influence of the microstructure on Weibull plot parameters and the failure mode will be shown. Interconnect defects such as nonuniform phase distribution, low-melting structure accumulation, and void formation are discussed. Recommendations on mixed assembly and rework parameters are given.     

Real time cardiac image registration during respiration: a time series prediction approach

Cardiac image registration is drawing attention for a range of merits in integrating and enhancing real-time (RT) images using a priori and complementary images of the myocardium, which might additionally be captured from other modalities. Myocardial stem cell delivery and radio-frequency ablation are some of the cases that could benefit from RT registration of high quality images. Unfortunately, most of these applications are of long duration, and must account in some manner for respiratory motion. Moreover, registration is not so keen as to compensate for these motions. Time series prediction techniques could compensate this shortcoming by proposing future approximate displacements caused by respiratory motion. In this study, we propose a three-stage framework for RT 2D into 3D cardiac image registration during respiration, composed of prior registration to extract the trend of respiratory motion and to calibrate a set of time series predictors for future motion prediction, as well RT registration to update estimated transform parameters. The proposed approach was validated in the course of four simulations and shows acceptable results for clinical circumstances.     

Dynamic Fractional Frequency Reuse (DFFR) with AMC and Random Access in WiMAX System

In this paper; dynamical resource allocation scheme is proposed to improve throughput and fairness in the modern broadband wireless systems such as IEEE 802.16 Worldwide Interoperability for Microwave Access. To assign the subcarriers to users, dynamic fractional frequency reuse is used. In dynamic fractional frequency reuse, each cell is partitioned into two regions, one called super region and another called regular region. Regular region is divided into 3 parts which correspond to the three sectors. In this method, a utility function is firstly used for the subcarrier allocation to the geographical regions and then opportunistic scheduling is applied for the assignment subcarriers to users in each cell. In order to increase the throughput of the system, adaptive modulation and coding techniques are used. Using dynamic fractional frequency reuse reduces fairness among users of a cell. Therefore a random access sub-band is applied to improve the fairness of the system.     

硅含量对TIG焊Al-Si/SiCp复合层包覆A380铝合金显微组织的影响

采用钨极惰性气体（TIG）在铸态A380铝合金表面制备复合涂层。将Al,Si和SiC粉末混合物与硅酸钠溶液混合后涂覆在基材上,采用TIG焊进行表面熔化,在基体表面制备Al-SiC涂层。采用XRD、SEM和EDS研究显微组织的变化,采用显微硬度和滑动磨损试验研究包覆层的性能。结果表明,SiC粒子均匀分布在树枝状的铝基体中。加入过量的硅造成包覆层共晶和粗大硅粒子的形成,从而导致包覆层具有较高的硬度和耐磨性。