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排序方式: 共有487条查询结果,搜索用时 31 毫秒
81.
Salim Christian Makhoul Abdallah Couturier Raphaël 《Multimedia Tools and Applications》2020,79(3-4):1801-1819
Multimedia Tools and Applications - Wireless sensor networks (WSN) have become the rising stars of technology. Every object in this world tends to be sensorly developped, monitored and controlled.... 相似文献
82.
83.
We provide a new mixed finite element analysis for linear elastodynamics with reduced symmetry. The problem is formulated as a second order system in time by imposing only the Cauchy stress tensor and the rotation as primary and secondary variables, respectively. We prove that the resulting variational formulation is well-posed and provide a convergence analysis for a class of \({\mathrm {H}}(\mathop {{\mathrm {div}}}\nolimits )\)-conforming semi-discrete schemes. In addition, we use the Newmark trapezoidal rule to obtain a fully discrete version of the problem and carry out the corresponding convergence analysis. Finally, numerical tests illustrating the performance of the fully discrete scheme are presented. 相似文献
84.
Little is known about the hydrogenation of fused aromatic nuclei during the liquefaction of coal under the influence of Lewis acid catalysts. This study was conducted to establish the effects of catalyst acidity on the activity and selectivity of Lewis acid catalysts, the sources of hydrogen involved in hydrogenation and cracking, and the relations between reactant structure and reactivity. Two-ring aromatic and hydroaromatic compounds were used to simulate some of the structural units present in coal. The catalysts examined were ZnCl2 and AlCl3. ZnCl2 is less active than AlCl3 for both hydrogenation and cracking but it does not promote the formation of tars via Scholl condensation: Methyl or hydroxyl substitution of the reactants greatly enhances their reactivity towards hydrogenation and cracking. The source of hydrogen consumed during hydrogenation depends on the choice of catalyst. In the presence of AlCl3, Scholl condensation of aromatic nuclei serves as the principal source of hydrogen. Molecular hydrogen is used exclusively, though, when hydrogenation is catalysed by ZnCl2. The formation of reaction products and the trends in reactant reactivity can be interpreted on the basis of carbonium ion mechanisms. The results of this study provide a basis for assessing the extent of hydrogenation occurring during the liquefaction of coal using ZnCl2 or AlCl3. 相似文献
85.
In this study some of the important properties of experimentally manufactured wood–plastic composites (WPC) were determined. Specimen having 60% and 80% particle and fiber of radiata pine (Pinus radiata ) were mixed with polypropylene (plastic) and four different additives, namely Structor TR 016 which is coupling agent, CIBA anti-microbial agent (IRGAGUARD F3510) as fungicide, CIBA UV filter coating (TINUVIN 123S), CIBA blue pigment (Irgalite), and their combinations. Based on the initial finding of this work static bending properties of the samples enhanced as above chemicals were added into both particle and fiber-based specimens. Thickness swelling of the samples were also improved with having additives in the panels. Micrographs taken on scanning electron microscope (SEM) revealed that coupling agent and pigment resulted in more homogeneous mixture of wood and plastic together. Two surface roughness parameters average roughness (Ra) and maximum roughness (Rmax) used to evaluate surface characteristics of the samples showed that particle based samples had rougher surface characteristics than those of fiber based ones. No significant influence of chemicals added in the samples was found on surface roughness values of the samples manufactured from particle and fiber of radiata pine. 相似文献
86.
New Circulating Circular RNAs with Diagnostic and Prognostic Potential in Advanced Colorectal Cancer
Maria Radanova Galya Mihaylova Oskan Tasinov Desislava P. Ivanova George St. Stoyanov Neshe Nazifova-Tasinova Rostislav Manev Ayshe Salim Miglena Nikolova Diana G. Ivanova Nikolay Conev Zhasmina Mihaylova Ivan Donev 《International journal of molecular sciences》2021,22(24)
Circular RNAs (circRNAs) are a group of special endogenous long non-coding RNAs which are highly stable in the circulation, and, thus, more suitable as new biomarkers of colorectal cancer (CRC). The aim of our study was to explore the plasma expression levels of four circRNAs: has_circ_0001445, hsa_circ_0003028, hsa_circ_0007915 and hsa_circ_0008717 in patients with CRC and to evaluate their associations with clinicopathological characteristics and the clinical outcome of the patients. CircRNAs were extracted from patients’ plasma obtained prior to chemotherapy. Their expression levels were measured by qPCR and calculated applying the 2−ΔΔCt method. The levels of all four circRNAs were significantly increased in the plasma of CRC patients. At the optimal cut-off values hsa_circ_0001445 and hsa_circ_0007915 in plasma could significantly distinguish between patients with or without metastatic CRC with 92.56% sensitivity and 42.86% specificity, and with 86.07% sensitivity and 57.14% specificity, respectively. The mean overall survival (OS) of patients with high/intermediate expression of hsa_circ_0001445 was 30 months, significantly higher in comparison with the mean OS of the patients with low expression—20 months (log-rank test, p = 0.034). In multivariate Cox regression analysis, the low levels of hsa_circ_0001445 were also associated with shorter survival (HR = 1.59, 95% CI: 1.02–2.47, p = 0.040). A prognostic significance of hsa_circ_0001445 for patients with metastatic CRC was established. 相似文献
87.
We present a high-efficiency, low-cost wavelength division multiplexer to record cardiac optical action potentials (APs) within the myocardial wall using optical fibers. APs with signal-to-noise ratio as high as 60, without spatial or temporal averaging, and as high as 200, with median-filtering, were recorded in rabbit ventricle. 相似文献
88.
Fronheiser MP Light ED Idriss SF Wolf PD Smith SW 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(1):100-105
Modifications were made to a commercial real-time, three-dimensional (3-D) ultrasound system for near simultaneous 3-D scanning with two matrix array transducers. As a first illustration, a transducer cable assembly was modified to incorporate two independent, 3-D intra-cardiac echo catheters, a 7 Fr (2.3 mm O.D.) side scanning catheter and a 14 Fr (4.7 mm O.D) forward viewing catheter with accessory port, each catheter using 85 channels operating at 5 MHz. For applications in treatment of atrial fibrillation, the goal is to place the sideviewing catheter within the coronary sinus to view the whole left atrium, including a pulmonary vein. Meanwhile, the forward-viewing catheter inserted within the left atrium is directed toward the ostium of a pulmonary vein for therapy using the integrated accessory port. Using preloaded, phasing data, the scanner switches between catheters automatically, at the push of a button, with a delay of about 1 second, so that the clinician can view the therapy catheter with the coronary sinus catheter and vice versa. Preliminary imaging studies in a tissue phantom and in vivo show that our system successfully guided the forward-viewing catheter toward a target while being imaged with the sideviewing catheter. The forward-viewing catheter then was activated to monitor the target while we mimicked therapy delivery. In the future, the system will switch between 3-D probes on a line-by-line basis and display both volumes simultaneously. 相似文献
89.
Loss behavior of viscoelastic sandwich structures: A statistical-continuum multi-scale approach 总被引:1,自引:0,他引:1
Yao KoutsawaWiyao Leleng Azoti Salim Belouettar Rodolphe MartinEvgeny Barkanov 《Composite Structures》2012,94(4):1391-1397
This work presents a multi-scale model of viscoelastic constrained layer damping treatments for vibrating plates/beams. The approach integrates a finite element (FE) model of macro-scale vibrations and a statistical-continuum homogenization model to include effects of micro-scale structure and properties. The statistical-continuum homogenization model makes the micro- to macro-scale transition to approximate the effective behavior of the heterogeneous core by using n-point probability functions. A simple sound transmission model is used to show the effect of material microstructure on the sound transmission loss of the sandwich structure. The damping behavior resulting from the presence of voids and negative stiffness regions in the core material is modeled. This study clearly shows that, it is of high interest to research either material structures or processing techniques which lead to negative stiffness behavior. The results also poignantly show that the proposed multi-scale model yields insight on heterogeneous material behavior leading to increased damping properties and ultimately enhances the ability to design sandwich beam/plates. 相似文献
90.
Inhibitory effect of acid concentration,aging, and different packaging on Escherichia coli O157:H7 and on color stability of beef
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Ana Paula A. A. Salim Anna C. V. C. S. Canto Bruno R. C. Costa‐Lima Julia S. Simoes Pedro H. N. Panzenhagen Marion P. Costa Robson M. Franco Teófilo J. P. Silva Carlos A. Conte‐Junior 《Journal of Food Processing and Preservation》2018,42(1)
The presence of pathogens such as Escherichia coli O157:H7 (EC) represents risks to public health and to economy of Brazilian beef industry. In this context, the application of lactic acid (LA) is an efficient practice employed to reduce bacterial count without compromising consumer safety. Our aim was to verify the inhibitory effect of LA application combined with aging and different packaging on EC and its effects on beef color. The LA effect on EC counts was concentration dependent during aging and storage, with T2 (10% of LA added) demonstrating greater (p < .05) reductions than T1 (5% of LA added). Aging did not affect (p > .05) EC counts, however reduced (p < .05) the total aerobic mesophilic bacteria. LA application promoted a decrease on beef redness (p > .05) after application and during storage. LA treatment (T2) promoted a reduction in E. coli O157:H7, despite the effects on beef color.