Investigation of the Neuroprotective Impact of Nimodipine on Neuro2a Cells by Means of a Surgery-Like Stress Model

Nimodipine is well characterized for the management of SAH (subarachnoid hemorrhage) and has been shown to promote a better outcome and less DIND (delayed ischemic neurological deficits). In rat experiments, enhanced axonal sprouting and higher survival of motoneurons was demonstrated after cutting or crushing the facial nerve by nimodipine. These results were confirmed in clinical trials following vestibular Schwannoma surgery. The mechanism of the protective competence of nimodipine is unknown. Therefore, in this study, we established an in vitro model to examine the survival of Neuro2a cells after different stress stimuli occurring during surgery with or without nimodipine. Nimodipine significantly decreased ethanol-induced cell death of cells up to approximately 9% in all tested concentrations. Heat-induced cell death was diminished by approximately 2.5% by nimodipine. Cell death induced by mechanical treatment was reduced up to 15% by nimodipine. Our findings indicate that nimodipine rescues Neuro2a cells faintly, but significantly, from ethanol-, heat- and mechanically-induced cell death to different extents in a dosage-dependent manner. This model seems suitable for further investigation of the molecular mechanisms involved in the neuroprotective signal pathways influenced by nimodipine.     

Compressible Magnetorheological Fluids Based on Composite Polyurethane Microspheres

A novel CMRF is synthesized from modified silicone oil, containing composite polyurethane microsphere additives, and surface‐coated iron particles. The CMRF is designed to act as a liquid spring with controllable damping properties in a damper system. The fluid compressibility is characterized by force/displacement measurements. The addition of composite polyurethane‐microspheres increases the strength and compressibility of the fluid. It also decreases the concentration of iron particles needed in order to achieve the same yield stress as commercially available MRF. Surface coating surface of the iron particles with poly(2,3,4,5,6‐pentafluorostyrene) via RAFT provides dispersion stability.

     

An Insight into the Silanization of Montmorillonite Nanoparticles

The purpose of this study is to investigate the effect of reaction conditions on the silanization of montmorillonite nanoparticles using methacryloxypropyltrimethoxysilane (γ–MPS) and to establish relationships between the reaction conditions, the grafting percentage, and the silane arrangement on the particles. The silanization reaction was performed in the following conditions: (i) acidic ethanol-water solution with a pH of 5 and (ii) basic cyclohexane with a pH of 9. To characterize the surface of montmorillonite nanoparticles, analytical methods such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), CHN elemental analysis, and X-ray diffraction (XRD) diffraction were utilized. In addition, the dispersion stability of modified particles suspended in different solvents was investigated using a separation analyzer. The results revealed silane grafting in cyclohexane (pH?=?9) achieved higher silanization efficiency, leading to a larger basal spacing in montmorillonite nanoparticles. A parallel arrangement was also suggested for the silane molecules on the surface of the nanoparticles. The higher hydrophobicity of the modified nanoparticles and the decreased overall density of the grafted particles led to a better dispersion in ethanol and toluene.     

A consecutive modal pushover procedure for estimating the seismic demands of tall buildings

The nonlinear static procedure (NSP), based on pushover analysis, has become a favourite tool for use in practical applications for building evaluation and design verification. The NSP is, however, restricted to single-mode response. It is therefore valid for low-rise buildings where the behaviour is dominated by the fundamental vibration mode. It is well recognized that the seismic demands derived from the conventional NSP are greatly underestimated in the upper storeys of tall buildings, in which higher-mode contributions to the response are important. This paper presents a new pushover procedure which can take into account higher-mode effects. The procedure, which has been named the consecutive modal pushover (CMP) procedure, utilizes multi-stage and single-stage pushover analyses. The final structural responses are determined by enveloping the results of multi-stage and single-stage pushover analyses. The procedure is applied to four special steel moment-resisting frames with different heights. A comparison between estimates from the CMP procedure and the exact values obtained by nonlinear response history analysis (NL-RHA), as well as predictions from modal pushover analysis (MPA), has been carried out. It is demonstrated that the CMP procedure is able to effectively overcome the limitations of traditional pushover analysis, and to accurately predict the seismic demands of tall buildings.     

Interactive 3D content modeling for Digital Earth

Digital Earth is a global reference model for integrating, processing and visualizing geospatial datasets. In this reference model, various data-types, including Digital Elevation Models (DEM) and imagery (orthophotos), are universally and openly available for the entire globe. However, 3D content such as detailed terrains with features, man-made structures, 3D water bodies and 3D vegetation are not commonly available in Digital Earth. In this paper, we present an interactive system for the rapid creation and integration of these types of 3D content to augment Digital Earth. The inputs to our system include available data sources, such as DEM and imagery information depicting landscapes and urban environments. The proposed system employs sketch-based and image-assisted tools to support interactive creation of textured 3D content. For adding terrain features visible in orthophotos, and also the basin of water bodies, we use a multiscale least square surface fitting to generate an adaptive triangular subdivision. For modeling forests and vegetation, we use image-based techniques and take advantage of visible regions and colors of forests in orthophotos. For 3D man-made structures, starting from a single photograph, we provide a simple image-assisted sketching tool to extract these objects, correct for perspective distortion and place them into desired locations.     

Analysis of the Young’s Modulus and Impact Strength of A-Glass/Epoxy/Nano-silica Ternary Nano-composites Using Surface Response Methodology

The goal of this study was to investigate the effect of the simultaneous presence of A-glass fibers and nano-silica on an epoxy matrix using the response surface methodology (RSM). The Box–Behnken method was used to design experiments to determine the main and interaction effect between variables including glass fibers (GF), glass fibers length (GFL) and nano-silica (NS) in three levels (5, 10 and 15 wt.% for GF; 3, 6 and 9 mm for GFL; and 0, 0.75 and 1.5 wt.% for NS). The RSM provides a model for each response with high confident. Moreover, RSM models were used to predict the optimal case for the maximum Young’s modulus and impact strength. The optimal case was estimated to be 15 wt.% for GF at 5.9697 mm length and 0.8182 wt.% for NS. Experimental tests showed an agreement with the predicted values. Further, scanning electron microscopy was used to evaluate the morphology of the samples. It was found that the length of the glass fiber and nanoparticles had the most effect on the Young’s modulus and impact strength, respectively.     

Applications of quantum dots in optical fiber luminescent oxygen sensors

The potential applications of luminescent semiconductor nanocrystals to optical oxygen sensing are explored. The suitability of quantum dots to provide a reference signal in luminescence-based chemical sensors is addressed. A CdSe-ZnS nanocrystal, with an emission peak at 520 nm, is used to provide a reference signal. Measurements of oxygen concentration, which are based on the dynamic quenching of the luminescence of a ruthenium complex, are performed. Both the dye and the nanocrystal are immobilized in a solgel matrix and are excited by a blue LED. Experimental results show that the ratio between the reference and the sensor signals is highly insensitive to fluctuations of the excitation optical power. The use of CdTe, near-infrared quantum dots with an emission wavelength of 680 nm, in combination with a ruthenium complex to provide a new mechanism for oxygen sensing, is investigated. The possibility of creating oxygen sensitivity in different spectral regions is demonstrated. The results obtained clearly show that this technique can be applied to develop a wavelength division multiplexed system of oxygen sensors.     

Smooth reverse subdivision

In this paper we present a new multiresolution framework that takes into consideration reducing the coarse points’ energy during decomposition. We start from initial biorthogonal filters to include energy minimization in multiresolution. Decomposition and reconstruction are main operations for any multiresolution representation. We formulate decomposition as smooth reverse subdivision, based on a least squares problem. Both approximation of overall shape and energy are taken into account in the least squares formulation through different weights.Using this method, significant smoothness in decomposition of curves and tensor product surfaces can be achieved; while their overall shape is preserved. Having smooth coarse points yields details with maximum characteristics. Our method works well with synthesizing applications in which re-using high-energy details is important. We use our method for finding the smooth reverse of three common subdivision schemes. We also provide examples of our method in curve synthesis and terrain synthesis applications.     

A Novel Approach to Efficient Resource Allocation in NOMA Heterogeneous Networks: Multi-Criteria Green Resource Management

ABSTRACT

Nowadays, Green Communications has been introduced as an appealing approach to achieve the maximum degree of energy efficiency in new generation heterogeneous networks. To achieve the effective resource management, this paper suggests a novel approach to joint optimal power allocation and user association techniques in which cells are powered via a common grid network and alternative energy resources. This research focuses on resource assignment in energy-cooperated heterogeneous systems with non-orthogonal multiple access so that the quality of experience indexes are assumed to be bounded during multicell multicast sessions. The solution to the introduced problem has been developed to a mixed-integer programming framework in which the goal function is solved based on a Lagrangian convex optimization method by considering user association constraints. The effectiveness of the suggested approach has been confirmed by the numerical results and we compared the complexity of the proposed model to those of the conventional schemes. Also, the results reveal that non-orthogonal multiple access can provide greater energy efficiency than orthogonal multiple access in heterogeneous wireless networks.