Dynamic mechanical, thermal, physico-mechanical and morphological properties of LLDPE/EMA blends

The effect of blend composition on the morphology, dynamic mechanical properties, thermal and physico-mechanical properties of linear low density polyethylene (LLDPE)/ ethylene-co-methyl acrylate (EMA) blends were studied. The blend showed both dispersed and continuous phase morphology that depends on the blend composition. A co-continuous structure is formed for blends containing 50 wt% of EMA. Dynamic mechanical studies showed that flexibility of the blend enhanced with the expansion of the amorphous region as EMA content increased. However, two separate melting temperature peak observed in differential scanning calorimetry (DSC) analysis indicate that the blends are immiscible in crystalline region of the two polymers. X-ray diffraction (XRD) studies showed that crystallinity of blends decreases with increase in EMA content and negative deviation of tensile strength from the mixing rule indicates the poor interfacial adhesion between the two components. FTIR spectroscopy established the lack of chemical interaction between LLDPE and EMA, which support the SEM, DSC, DMA and XRD observations. Parallel-Voids model has been applied to characterize phase morphology of these blends.     

An optimal time multiplication free algorithm for edge detection on a mesh

This paper demonstrates an optimal time, fully systolic algorithm for edge detection on a mesh connected processor array. It uses only inexpensive addition and comparison operations which makes it ideal for fine grained parallelism in VLSI. Given anN xN image in the form of a two-dimensional array of pixels, our algorithm computes the Sobel and Laplacian operators for skimming lines in the image and then generates the Hough array using thresholding. The Hough transforms forM different angles of projection are obtained in a fully systolic manner inO(M+N) time, which is asymptotically optimal. In comparison, a previously published multiplication free algorithm has a time complexity ofO(NM). An implementation of our algorithm on a mesh connected finegrained processor array is discussed, which computes at the rate of approximately 170,000 Hough transforms per second using a 50 MHz clock.This research was partially supported by National Science Foundation under Grant No. MIP 8902636     

Ce–Nd codoping effect on the structural and optical properties of TiO2 nanoparticles

We report the changes in the structural and optical property of TiO₂ nanoparticles on codoping Ce–Nd ions. X-ray diffraction clearly demonstrates the structural changes occurring in the codoped TiO₂ nanoparticle. Oxygen defects disturb the TiO bonds in the TiO₆ octahedra and result in the shifting and broadening of the Raman E_g peak. Pure TiO₂ nanoparticles show absorption peak in the UV region. However, codoped TiO₂ nanoparticles exhibit absorption peaks in the visible region corresponding to the f–d and f–f electronic transition of Ce³⁺ and Nd³⁺ in the crystalline environment of TiO₂. The visible emission peaks of pure and codoped TiO₂ nanoparticles are mainly associated with oxygen vacancies. Incorporation of cerium intensifies the visible emission peaks of TiO₂ nanoparticles. On the other hand, codoping of Nd forms some non radiative recombination centres and increases the possibility of emission energy transfer among dopants, defects, thereby quenching the intensity of the visible emission peaks.     

Conceptual Issues in Framing Theory: A Systematic Examination of a Decade's Literature

Although many scholars have pointed out problems in framing research, there has been very few systematic examinations of the published literature. To examine the common conceptual debates, the present study content analyzes framing literature from 93 peer‐reviewed journals for a decade. Two methods were employed for the sample: First, every journal identified as a “communication journal” in the Journal Citation Report was included; second, keyword searches in electronic databases were used. The main findings showed that framing studies have concentrated more on message design and “unique” frames. Consistent with existing debates, results highlight the lack of research about production of frames and mixed frames. This examination of a decade's published literature reveals better direction for future research.     

Study of photocatalytic properties of clay intercalated semiconductor composite material of guanidinium tetrachloroferrate for oxidative degradation of model dye in sunlight

Journal of Materials Science: Materials in Electronics - Herein, different weight percentage ratios composites of montmorillonite-K10 clay (Mt) with semiconductor organic salt...     

Estimation of laser beam pointing parameters in the presence of atmospheric turbulence

The problem of estimating mechanical boresight and jitter performance of a laser pointing system in the presence of atmospheric turbulence is considered. A novel estimator based on maximizing an average probability density function (pdf) of the received signal is presented. The proposed estimator uses a Gaussian far-field mean irradiance profile, and the irradiance pdf is assumed to be lognormal. The estimates are obtained using a sequence of return signal values from the intended target. Alternatively, one can think of the estimates being made by a cooperative target using the received signal samples directly. The estimator does not require sample-to-sample atmospheric turbulence parameter information. The approach is evaluated using wave optics simulation for both weak and strong turbulence conditions. Our results show that very good boresight and jitter estimation performance can be obtained under the weak turbulence regime. We also propose a novel technique to include the effect of very low received intensity values that cannot be measured well by the receiving device. The proposed technique provides significant improvement over a conventional approach where such samples are simply ignored. Since our method is derived from the lognormal irradiance pdf, the performance under strong turbulence is degraded. However, the ideas can be extended with appropriate pdf models to obtain more accurate results under strong turbulence conditions.     

Remarkable Vapochromic Behavior of Pure Organic Octahedron Embedded in Porous Frameworks

Vapochromic behavior is employed to selectively monitor the vapor changes in surrounding environment, particularly for toxic gas leaking and floating detection. Thus, sensitive trapping and accurate response to different toxic vapors are critical factors in vapochromic sensing. In this work, a self‐assembled hybrid that consists of fluorescent organic octahedron encapsulated by metal–organic polyhedron (MOP) is reported. The fluorescent octahedron is used as a responsive sensor to probe various solvent vapors, while the MOP is employed as a protector to prevent the corrosion of solvents to the organic octahedron. The hybrid exhibits remarkable vapochromic behavior to different solvents, and shows the highest selectivity and sensitivity specifically to acetone. In addition, acetone vapor under different conditions is utilized for further studying the response mechanism of the hybrid. This work presents a promising vapochromic sensor with good stability, selectivity, and sensitivity. The study is expected to open up the applicability of MOP‐based hybrids for specific molecular capture, interim storage, controlled release, and advanced sensing.     

An efficient and robust heterogeneous mesoporous montmorillonite clay catalyst for the Biginelli type reactions

Three component coupling reactions of aldehyde, β-ketoester (or β-diketone) and urea (or substituted urea) were carried out by using acid activated montmorillonite clay (AT-Mont.) catalyst having surface area about 400 m²/g for the facile synthesis of 3,4-dihydropyrimidin-2(1H)-ones via the Biginelli reactions under mild reaction conditions. The activation of montmorillonite clay was carried out with HCl under controlled conditions for generating nanopores (size 2–7 nm) into the matrix. This porous catalyst has promising feature for Biginelli reaction such as easy removal of the catalyst, short reaction time, high yield with 100% selectivity and easy workup procedure. Powder XRD, SEM-EDX, N₂ adsorption, pyridine adsorbed FT-IR and TPD analysis were carried out to characterize the solid porous AT-Mont. The catalysts can be recycled and reused several times without significant loss of their catalytic activity.     

Recent development in thermoplastic/wood composites and nanocomposites: A review

Thermoplastic composites filled with wood-base fillers have gained increasing attention, because compared to virgin polymers they have many advantages of light weight, high strength and stiffness, low cost, biodegradability and renewability. These advantages let them find a large dispersal in many areas of technical applications. However, poor interfacial interaction between hydrophilic wood-base fillers and hydrophobic polymer matrices should be improved to get reasonable physical properties for their wide applications. The interfacial interaction could be improved by addition of coupling agents and chemical modifications of wood-base fillers. To improve physical properties of the thermoplastic/wood composites, further nanofillers can be incorporated. This review summarizes recent developments in thermoplastic/wood composites and deals with wood-base fillers for thermoplastics, various interface modification methods and various thermoplastic/wood composites as well as nanocomposites. This review can provide reasonable future perspectives in this research area and stimulate development of new innovative thermoplastic/wood composites as well as nanocomposites.