Random poly(ε‐caprolactone‐L‐alanine) by direct melt copolymerization

A series of random polyesteramides (PEAs) with a range of molar composition from 90/10 to 50/50 were synthesized by direct melt polycondensation of ε‐caprolactone and l ‐alanine. Their structure was fully characterized by Fourier transform IR and NMR spectroscopy. The resulting copolymers are completely amorphous with the exception of PEA‐90/10 which possesses a semicrystalline structure. These PEAs present increasing glass transition temperatures at increasing l ‐alanine contents and exhibit fairly good thermal stability with 10% mass loss temperatures reaching 315 °C. © 2020 Society of Industrial Chemistry     

Structural, Magnetic, and Magnetocaloric Properties of La0.5M0.1Sr0.4MnO3 (M=Bi, Eu, Gd, and Dy) Perovskite Manganites

Structural, magnetic, and magnetocaloric properties of La_0.5M_0.1Sr_0.4MnO₃ (M=Bi, Eu, Gd, and Dy) powder samples, synthesized using the solid-state reaction at high temperature, have been experimentally investigated. X-ray diffraction analysis using the Rietveld refinement show that La_0.5Bi_0.1Sr_0.4MnO₃ sample is single phase and crystallizes in the rhombohedral system with $R\overline{3}c$ space group whereas a mixture of orthorhombic (Pbnm) and rhombohedral ( $R\overline{3}c$ ) phases is observed for M=Eu, Gd, and Dy compounds. The Curie temperature, T _C , shifts to lower temperature with decreasing the average A-site ionic radius 〈r _A 〉, which is consistent with large cationic disorder. Arrott plots show that all our samples exhibit a second order magnetic phase transition. From the measured magnetization data of La_0.5M_0.1Sr_0.4MnO₃ (M=Bi, Eu, Gd, and Dy) samples as a function of magnetic applied field, the associated magnetic entropy change |ΔS _M | has been determined. In the vicinity of T _C , |ΔS _M | reached, in a magnetic applied field of 1 T, maximum values of 0.98 J/kg?K, 1.01 J/kg?K, 0.81 J/kg?K, and 0.77 J/kg?K for M=Bi, Eu, Gd, and Dy, respectively.     

Towards a computer aided diagnosis (CAD) for brain MRI glioblastomas tumor exploration based on a deep convolutional neuronal networks (D-CNN) architectures

Manuel brain glioblastomas tumor exploration through MRI modalities is time-consuming. It is considered as a harmful and critical task due to highly inhomogeneous tumor regions composition. For this reason, clinicians recommend the Computer-Aided Diagnosis (CAD) tools to ensure a more accurate diagnostic. Based on convolutional Deep-Learning algorithms, this paper investigates a fully automatic CAD for brain Glioblastomas tumors exploration including three steps: pre-processing, segmentation, and finally classification. A denoising and an automatic contrast enhancement method have been applied to preprocess the MRI scans. A Multi-Modal Cascaded U-net architecture, based on Fully Convolutional deep Network (FCN), has been adopted for the Region of Interest (ROI) extraction and finally, Deep Convolutional Neural Network (D-CNN) architecture has been used to classify brain glioblastomas tumor into High-Grade (HG) and Low-Grade (LG). Experiments were performed on the Multimodal Brain Tumor Segmentation Challenge BraTS-2018 datasets benchmark. Several validations metric have been adopted to assess the CAD’s performances. The Dice Metric (DM) parameter has been calculated between the obtained segmentation results and the available ground truth data. The accuracy parameter has been computed for classification performance evaluation. The higher DM and accuracy values could attest the performance and the efficiency of the proposed CAD tool.

     

2017铝合金搅拌摩擦焊接头焊接参数和硬化参数的关系(英文)

对2017铝合金进行搅拌摩擦焊接,表述Swift硬化规律。采用面心复合设计方法进行焊接接头的拉伸实验设计。采用基于最小二乘法和响应面法的2种模型评估搅拌摩擦焊各焊接因素对硬化参数的影响。采用到有限元程序Abaqus来模拟焊接接头拉伸测试结果。相对平均偏差判据结果表明,实验结果和模拟结果吻合较好。这些结果能用于实验多目标优化,实行具体焊接或完成搅拌摩擦焊接零件成形过程中塑性变形的数值模拟,如液压成形、弯曲度和锻造。     

Glassy ferromagnetism in La0.75Sr0.25-xKxCoO3 polycrystalline perovskite cobaltites

In this paper, the structural and magnetic properties of La_0.75Sr_0.25-xK_xCoO₃ (0≤x≤0.15) powder samples are reported. X-ray diffraction analysis using Rietveld refinement show that all our samples crystallize in the rhombohedral structure with \( R\overline{3}c \) space group. At low temperatures, with increasing K amount, the samples change from ferromagnetic like behavior (x?=?0, 0.05 and 0.1) to spin glass one (x?=?0.15). The ferromagnetic-paramagnetic transition temperature decreases with increasing K amount from 235K (x?=?0) to 200K (x?=?0.1). In the paramagnetic phase, all our synthesized samples obey the Curie-Weiss law. In the vicinity of T_C, the magnetic entropy change |ΔS _M | for La_0.75Sr_0.2K_0.05CoO₃ sample reached maximum values of 0.47Jkg/K and 2.27Jkg/K under magnetic field variation in the range 1T and 7T, respectively. The magnetization hysteresis loops demonstrate a weakening the ferromagnetism with increasing K content.     

Inactivation of Vegetative and Sporulated Bacteria by Dry Gaseous Ozone

Inactivation by gaseous ozone of different types of microorganisms is successfully achieved provided, as is well known, the gaseous phase is strongly humidified. The inactivation mechanisms and species involved in this process are, however, not yet clearly identified. To gain insight, we considered exposure of bacterial spores to dry rather than humidified ozone, a less complex chemical environment. In contrast to most of the published literature, it is shown that, under strict dry ozone conditions, bacterial spores can be inactivated, but to a degree that is largely dependent on the spore type and substrate material. In this case, the O₃ molecule is determined to be responsible for the inactivation process through its diffusion into and oxidative action within the spore, as no outer erosion of the spore is detected. With humidified ozone, a higher inactivation efficiency is observed that is most probably related, in part, to the swelling of the spore, which facilitates the diffusion of oxidative species within it and up to the core; besides O₃, these oxidative agents stem from the interaction of O₃ with H₂O, which in the end leads to a heavily damaged spore structure, in contrast to dry-ozone exposure where the spore integrity is maintained.     

Significance of Arrhenius activation energy in flow and heat transfer of tangent hyperbolic fluid with zero mass flux condition

Microsystem Technologies - The current endeavor scrutinizes the flow of tangent hyperbolic fluid over a moving stretched surface. The characteristics of heat transfer are conferred by utilizing...     

Multi-pitch estimation based on multi-scale product analysis,improved comb filter and dynamic programming

There are many multi-pitch estimation methods, but most of them can’t perform perfectly for intrusion pitch detection. For this reason, a new multi-pitch detection approach is proposed. This method consists on the autocorrelation function of the Multi-scale product calculation of the mixture signal, its filtered version by a rectangular improved comb filter and the dynamic programming of the residual signal spectral density. First, we analyze the composite speech. Then, we apply the autocorrelation on the multi-scale product (AMP). We find the first pitch which represents the dominant one. Then, we apply the rectangular comb filter which has adaptive amplitude to remove the resulting signal from the original one. We operate AMP on the residue to obtain a pitch estimation of the intrusion. To improve the residue pitch estimation, we apply the dynamic programming to the spectral density of the residual signal to get optimum pitches corresponding also to intrusion signal. After that, we compare the two resulting pitch residue series to choose the most appropriate. Finally, this method is evaluated using the Cooke database and is compared to other well-known techniques. Experimental results confirm the strength and the performance of the proposed approach.