Development of isotropic compatible HDPE/PP blends for structural applications

In an attempt to provide superior products for the structural applications, this study aimed at preparing isotropic compatible high density polyethylene (HDPE)/ polypropylene (PP) blends without the use of the expensive compatibilization technique. Morphological and structural characterizations of the homopolymers and blends were carried out. In addition, some of the structurally important mechanical and thermal properties were characterized. Such characterizations were performed to investigate whether or not the blends are compatible and therefore acceptable for the structural applications. Scanning electron microscope (SEM) micrographs of the blend samples indicate that the interfacial adhesion between HDPE and PP phases is intimate in the 5/95 HDPE‐PP, good in the 85/15 HDPE‐PP and 95/5 HDPE‐PP, fair in the 30/70 HDPE‐PP and very poor in the 50/50 HDPE‐PP. Similarly, mechanical and thermal responses of the first three blends are remarkable. The 30/70 HDPE‐PP blend displays a fairly good performance. Whereas, the properties of the 50/50 HDPE‐PP blend are very poor. This decides that the first three blends are compatible and, therefore, structurally attractive materials. The fourth is partially compatible and, as a consequence, can be rather acceptable for the structural applications. However, the fifth is incompatible and, of course, is not acceptable for such applications. On the other hand, SEM micrographs and differential scanning calorimetry results indicate that the crystalline structures of individual polymers are appreciably affected by blending. Additionally, the study reveals that the end use performance of blends is strongly dependent on the crystalline structure changes occurring in each component due to blending as well as the compatibility between the blend components. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Economical assessment of private sector for power generation inEgypt

Developing a renewable energy source as a private generation system (PGS) is discussed. A proposed approach is presented for this issue which includes an economical model for deducing the rate of return on the capital invested under different utilization modes. These modes are a stand-alone system, a distribution-PGS connection, and a PGS central power station. The model was applied numerically to develop the rate of return on the capital invested for owning photovoltaic and wind energy systems in Egypt, and the results are presented     

Engineered s-Triazine-Based Dendrimer-Honokiol Conjugates as Targeted MMP-2/9 Inhibitors for Halting Hepatocellular Carcinoma

Despite the advances in developing MMP-2/9 inhibitors, off-target side effects and pharmacokinetics problems remain major challenges hindering their clinical success in cancer therapy. However, recent targeting strategies have clearly revitalized MMP research. Herein, we introduce new s-triazine-based dendrimers endowed with intrinsic MMP-2/9 inhibitory potential and tetherable to hepatocellular carcinoma-specific targeting ligands and anticancer agents via biodegradable linkages for targeted therapy. The designed dendrimeric platform was built with potential zinc-binding branching linkers (hydrazides) and termini (carboxylic acids and hydrazides) to confer potency against MMP-2/9. Preliminary cytotoxicity screening and MMP-2/9 inhibition assay of the free dendrimers revealed promising potency (MMP-9; IC₅₀=0.35–0.57 μM, MMP-2; IC₅₀=0.39–0.77 μM) within their safe doses (EC₁₀₀=94.15–42.75 μM). The hydrazide dendrimer was comparable to NNGH and superior to the carboxylic acid analogue. MTT assay showed that the free dendrimers were superior to the reference anticancer agent honokiol. Their anticancer potency was enhanced by HK conjugation, targeting ligands installation and PEGylation as exemplified by the hydrazide dendrimer conjugate (TPG₃−NH₂)-SuHK-FA-SuPEG (Huh-7; IC₅₀=5.54 μM, HepG-2; IC₅₀=10.07 μM) being 4 folds more active than HK, followed by the carboxylic acid conjugate (TPG₃−OH)-HK-LA-PEG (Huh-7; IC₅₀=14.97, HepG-2; IC₅₀=21.29 μM). This was consistent with apoptosis studies.     

Eco‐friendly produced lightweight structural graphene/polyamide 12 nanocomposite: Mechanical performance and the controlling microstructural mechanisms

The present study explores the potential use of graphene nanoplatelets (GL‐GNPs), synthesized from glucose through a new chemical approach that is facile, economical, and eco‐friendly alternative to the conventional Hummer's method, as a nanoreinforcement in polymers for the production of light‐weight structural polymer nanocomposites. Understanding the interface character of GL‐GNPs/Polyamide 12 (PA12) nanocomposites with various nanofiller loadings and how this affects their tensile behavior, are focal points of interest. Results reveal that enhancements in polymer stiffness and strength are superior at low GL‐GNPs content than higher contents. This is attributed to higher degree of GL‐GNPs exfoliation and increased polymer phase crystallinity. Interestingly, abundant small/imperfect PA12 crystallites have grown on the GL‐GNPs surface, strongly interlinking thus the polymer and graphene phases within nanocomposites. The intensity of such crystallites in interface region is the determinant of the nanocomposites' Young's modulus, assessed at small applied tensile stress. While the GL‐GNPs‐PA12 interfacial bonding is the determinant of yield and ultimate strengths, estimated at medium and high stress levels. Overall, the 1 wt% GL‐GNPs/PA12 nanocomposite is considered the optimum. Its low density and good mechanical performance among the previously developed graphene/Polyamide nanocomposites, propose promising future for GL‐GNPs‐based nanocomposites as ecofriendly and cost‐effective lightweight structural material. POLYM. ENG. SCI., 58:1201–1212, 2018. © 2017 Society of Plastics Engineers     

Effect of bio-alkyd resin oil content and viscosity on the adhesion of EPDM to polyester fabric

Three types of bio-alkyd resins varies in their oil content and viscosity were added to EPDM rubber mix loaded by three bonding system consisting of Hexamethylenetetramine, Resorcinol and Hydrated silica (HRH). The mixes were charged by certain amount of thermal carbon black. Rubber dough was spread on polyester sheet fabric. The peel strength was used to measure the adhesion strength. The rubber-proofed fabric subjected to UV irradiation at different period of times. The dielectric constant, volume resistivity, thermal stability, water and air permeability of the various rubber coated fabric were examined. The addition of the bio-alkyd resin improved the various mechanical and physical properties of the rubber coated fabric materials. The suggested mechanism of bio-alkyd resin between EPDM and polyester fabric was also studied.     

Image encryption based on a combination of multiple chaotic maps

Recent years have seen a rapid evolution of digital communications and an immense use of image transmissions over unsecured links. More specifically, some domains require the exchange of images depicting sensitive information, such as fingerprints, medical records and government or military satellite images. This creates a major challenge for researchers to come up with efficient and effective image encryption schemes. On the other hand, chaotic maps have proven suitable for such applications. This is because they exhibit characteristics such as ergodicity and sensitivity to control parameters and initial conditions. In this paper, an image encryption confusion-diffusion technique is proposed. First, the image pixels are disarranged resulting in a shuffled one which is then diffused through XORing its pixels with a secret key. This key is generated from a combination of different chaotic maps. Performance of the proposed scheme is evaluated utilizing various metrics. The proposed scheme is shown to be robust against differential attacks and resistant to statistical attacks. Its running time is very small which guarantees its efficiency and suitability for real time applications.

     

Impact of mainstream classroom setting on attention of children with autism spectrum disorder: an eye-tracking study

It has long been reported that children with autism spectrum disorder (ASD) exhibit attention difficulties while learning. They tend to focus on irrelevant information and can easily be distracted. As a result, they are often confined to a one-to-one teaching environment, with fewer distractions and social interactions than would be present in a mainstream educational setting. In recent years, inclusive mainstream schools have been growing in popularity due to government policies on equality rights. Therefore, it is crucial to investigate attentional patterns of children with ASD in mainstream schools. This study aims to explore the attentional behaviors of children with ASD in a virtual reality simulated classroom. We analyzed four eye-gaze behaviors and performance scores of 45 children: children with ASD (ASD n = 20) and typically developing children (TD n = 25) when performing attention tasks. The gaze behaviors included time to first fixate (TTFF), first fixation duration (FFD), average fixation duration (AFD) and the sum of fixation count (SFC) on fourteen areas of interest (AOIs) in the classroom. Our results showed that children with ASD exhibit similar gaze behaviors to TD children, but with significantly lower performance scores and SFC on the target AOI. These findings showed that classroom settings can influence attentional patterns and the academic performance of children with ASD. Further studies are needed on different modalities for supporting the attention of children with ASD in a mainstream setting.

     

Impact performance of hybrid laminated composites with statistical analysis

The main emphasis of this work is to fabricate a new composite system having high impact performance, light weight, cost-effective and reduced water absorption. Glass (G)–polypropylene (P) fibers reinforced epoxy composite laminates were fabricated using the hand lay-up technique. The impact response and water absorption capabilities of G–P fibers reinforced epoxy composites were investigated to know their suitability and adaptability for different industrial applications. Morphological studies of the fractured surfaces were performed using scanning electron microscopy (SEM). Two-parameter Weibull distribution function was used to obtain the scatter in the results and to construct the reliability graphs. These reliability graphs are important tools for helping the designers to understand and choose the suitable material for the required application. The proposed G–P/epoxy hybrid composites showed an improvement in the impact performance and reduction in water absorption capability compared to the host composites. The hybrid composite with G-fiber at the periphery and P-fiber at the core has lower void content and lower water uptake. The plies stacking sequence has almost no effect on edge-wise impact strength values, whilst it has a noticeable effect on flat-wise impact strength values. When P-layers are at the impacted face, the composite exhibits higher impact strength. Both edge-wise and flat-wise impact strengths increase when P/G fiber ratio increases.