PROBING HIDDEN POLYMERIC INTERFACES USINGIR-VISIBLE SUM-FREQUENCY GENERATION SPECTROSCOPY

Understanding the molecular-level processes underlying interfacial phenomena is important in the area of adhesion. We briefly introduce IR-visible sum-frequency generation spectroscopy (SFG) using a total-internal-reflection geometry for the study of polymer-air, polymer-solid, and polymer-polymer interfaces. The following examples, predominantly of work done in our lab, illustrating differences in molecular structure and dynamic properties at interfaces are presented: the air- and solid-interface structure of an amorphous polystyrene (PS) and a semicrystalline polymer with side-chain crystallinity, poly(octadecyl acrylate) (PA-18); structure of a polymer-polymer interface between thin films of a semicrystalline polymer with side-chain crystallinity, poly(vinyl-N-octadecylcarbamate- co-vinyl acetate), and an amorphous PS; thermal order-to-disorder transitions of the air and solid interface of PA-18, and the interface of this polymer with PS; and dynamic surface-relaxation studies of a rubbed PS film.     

3，4-二氢吡咯[2，1-c][1，4]噘嗪-1-酮及其7-芳酰基衍生物的设计与合成

以2-吡咯基三氯乙酮为主要原料,经过乙二醇单酯化、羟基氯取代、环合三步反应制得了3,4-二氢吡咯[2,1-c][1,4]噁嗪-1-酮;又经过Friedel—Crafts酰基化和环合反应制得了未见文献报道的7-芳酰基-3,4-二氢吡咯[2,1-c][1,4]噁嗪-1-酮它们及其某些重要中间体的结构分别采用红外光谱、质谱、核磁共振氢谱、核磁共振碳谱以及高分辨率质谱进行了表征．     

Magnetic Behavior of Trinuclear Vanadium(II)–Diamine Complexes. Part 2. Large Intramolecular Antiferromagnetic Exchange Interactions in a Triangular Unit

This study reports the magnetic structures of newly reported trinuclear vanadium(II)–diamine complexes. Using the isotropic Heisenberg exchange Hamiltonian, it is suggested that there are strong intramolecular antiferromagnetic interactions among the vanadium(II) ions. It is also suggested that these complexes are good candidates to the geometrically frustrated systems. For part 1 see A. Bayri, J. Inorg. Organomet. Polym. Mater., (in press) An erratum to this article can be found at     

Antiferromagnetic Exchange Interactions. Part 1. Newly Reported Nickel(II) Complex of the Antiprine Schiff Base of 3-Formylsalicylic Acid

This study reports the magnetic properties of newly reported nickel(II) complex of the antiprine Schiff base of 3-formylsalicylic acid. Using the isotropic magnetic interaction model it is suggested that there is a strong antiferromagnetic interactions between metal centers in dimeric units. It is also suggested that the system become demagnetized below a certain temperature. An erratum to this article can be found at     

Comparing emulsion polymerization of methacrylate-monomers with different hydrophilicity

A comprehensive experimental study concerning the influence of various types of initiator-emulsifier systems on emulsion polymerization of methacrylate monomers (2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) and butyl methacrylate (BMA)) reveals interesting relations between initiator and surfactant hydrophilicity on the one hand and the hydrophilicity of the monomers on the other hand. For the water-soluble HEMA stable latexes are only obtained if hydrophobic initiators such as 2,2′-azobisisobutyronitrile or dibenzoyl peroxide in combination with alkyl sulfate surfactants with carbon chain lengths greater than 10 or surface active initiators of the 2,2′-azobis(N-2′-methylpropanoyl-2-amino-alkyl-1)-sulfonate type with alkyl chain lengths greater than 8 are employed. Stable nano size range poly(2-hydroxyethyl methacrylate) (PHEMA) particles have been prepared also by batch emulsion polymerization using ionic surface active initiators (inisurfs). The results clearly show that the formation of stable latex particles requires a proper choice of the initiator-emulsifier system regarding its hydrophilic-hydrophobic balance. The PHEMA particles prepared with surface-active initiators keep their identity and spherical shape even in the dried state whereas in the case of the other initiator-emulsifier systems complete coagulation and coalescence occurs during drying.     

Profile based routing in vehicular ad-hoc networks

One of the main problems in the VANET(vehicular ad-hoc network)routing algorithms is how to establish the stable routes.The link duration in these networks is often very short because of the frequent changes in the network topology.Short link duration reduce the network efficiency.Different speeds of the vehicles and choosing different directions by the vehicles in the junctions are the two reasons that lead to link breakage and a reduction in link duration.Several routing protocols have been proposed for VANET in order to improve the link duration,while none of them avoids the link breakages caused by the second reason.In this paper,a new method for routing algorithms is proposed based on the vehicles trips history.Here,each vehicle has a profile containing its movement patterns extracted from its trips history.The next direction which each vehicle may choose at the next junction is predicted using this profile and is sent to other vehicles.Afterward each vehicle selects a node the future direction of which is the same as its predicted direction.Our case study indicates that applying our proposed method to ROMSGP(receive on most stable group-path)routing protocol reduces the links breakages and increases the link duration time.     

Indoor positioning: “an image-based crowdsource machine learning approach”

Multimedia Tools and Applications - Various technologies have been utilized today for recognizing client or user in the indoor areas. These technologies incorporate RSSI, Bluetooth Low Energy...     

Synchronization of Fractional Order Neutral Type Fuzzy Cellular Neural Networks with Discrete and Distributed Delays via State Feedback Control

Neural Processing Letters - The motivation behind this paper is to explore the issue of synchronization of fractional order neutral type fuzzy cellular neural networks with state feedback control....     

Video compression using frame redundancy elimination and discrete cosine transform coefficient reduction

The need of human beings for better social media applications has increased tremendously. This increase has necessitated the need for a digital system with a larger storage capacity and more processing power. However, an increase in multimedia content size reduces the overall processing performance. This occurs because the process of storing and retrieving large files affects the execution time. Therefore, it is extremely important to reduce the multimedia content size. This reduction can be achieved by image and video compression. There are two types of image or video compression: lossy and lossless. In the latter compression, the decompressed image is an exact copy of the original image, while in the former compression, the original and the decompressed image differ from each other. Lossless compression is needed when every pixel matters. This can be found in autoimage processing applications. On the other hand, lossy compression is used in applications that are based on human visual system perception. In these applications, not every single pixel is important; rather, the overall image quality is important. Many video compression algorithms have been proposed. However, the balance between compression rate and video quality still needs further investigation. The algorithm developed in this research focuses on this balance. The proposed algorithm exhibits diversity of compression stages used for each type of information such as elimination of redundant and semi redundant frames, elimination by manipulating consecutive XORed frames, reducing the discrete cosine transform coefficients based on the wanted accuracy and compression ratio. Neural network is used to further reduce the frame size. The proposed method is a lossy compression type, but it can reach the near-lossless type in terms of image quality and compression ratio with comparable execution time.

     

Enhanced halftone-based secure and improved visual cryptography scheme for colour/binary Images

Visual Cryptography (VC) is gaining attraction during the past few years to secure the visual information in the transmission network. It enables the visual data i.e. handwritten notes, photos, printed text, etc. to encrypt in such a way that their decryption can be done through the human visual framework. Hence, no computational assistance is required for the decryption of the secret images they can be seen through naked eye. In this paper, a novel enhanced halftoning-based VC scheme is proposed that works for both binary and color images. Fake share is generated by the combination of random black and white pixels. The proposed algorithm consists of 3 stages i.e., detection, encryption, and decryption. Halftoning, Encryption, (2, 2) visual cryptography and the novel idea of fake share, make it even more secure and improved. As a result, it facilitates the original restored image to the authentic user, however, the one who enters the wrong password gets the combination of fake share with any real share. Both colored and black images can be processed with minimal capacity using the proposed scheme.