The Effect of Antibacterial Particle Incorporation on the Mechanical Properties,Biodegradability, and Biocompatibility of PLA and PHBV Composites

The composites based on polylactide (PLA) and poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with the addition of antibacterial particles: silver (Ag) and copper oxide (CuO) are characterized. Basic mechanical properties and biodegradation processes, as well as biocompatibility of materials with human cells are determined. The addition of Ag or CuO to the polymers do not significantly affect their mechanical properties, flammability, or biodegradation rate. However, several differences between the base materials are observed. PLA‐based composites have higher tensile and impact strength values, while PHBV‐based ones have a higher modulus of elasticity, as well as better mechanical properties at elevated temperatures. Concerning biocompatibility, each of the tested materials support the growth of fibroblasts over time, although large differences are observed in the initial cell attachment. The analysis of hydrolytic degradation effects on the structure of materials shows that PHBV degrades much faster than PLA. The results of this study confirm the good potential of the investigated biodegradable polymer composites with antibacterial particles for future biomedical applications.     

Property enhancement in unsaturated polyester nanocomposites by using a reactive intercalant for clay modification

Polymeric nanocomposites were synthesized from unsaturated polyester (UPE) matrix and montmorillonite (MMT) clay using an in situ free radical polymerization reaction. Organophilic MMT was obtained using a quaternary salt of coco amine as intercalant having a styryl group making it a reactive intercalant. The resultant nanocomposites were characterized via X‐ray diffraction and transmission electron microscopy. The effect of increased nanofiller loading on the thermal and mechanical properties of the nanocomposites was investigated. All the nanocomposites were found to have improved thermal and mechanical properties as compared with neat UPE matrix, resulting from the contribution of nanolayer connected intercalant‐to‐crosslinker which allows a crosslinking reaction. It was found that the partially exfoliated nanocomposite structure with an exfoliation dominant morphology was achieved when the MMT loading was 1 wt %. This nanocomposite exhibited the highest thermal stability, the best dynamic mechanical performance and the highest crosslinking density, most probably due to more homogeneous dispersion and optimum amount of styrene monomer molecules inside and outside the MMT layers at 1 wt % loading. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Investigation of UV and I–V characteristics of high refractive index polymer thin film for optoelectronic applications

In this study, high refractive index polymer (HRIP) [poly(pentabromobenzyl methacrylate-co-glycidyl methacrylate)] was investigated to obtain its optical and electrical performance for optoelectronic applications. UV characteristics of the polymer in solution of tetrahydrofuran were obtained and optical band gap energy of the polymer was calculated as 3.8 eV. I–V characteristics of the polymer were investigated after HRIP thin film was prepared using spin coating technique. The electrical parameters such as barrier height Φ_Bo, ideality factor n and reverse saturation current I_o were extracted from the forward biasing I–V characteristics. At the same time, series resistance R_s and Φ_Bo were determined by using a modified Norde function combined with conventional forward I–V method.     

Unethical computer using behavior scale: A study of reliability and validity on Turkish university students

This study was carried out in a Turkish university with 216 undergraduate students of computer technology as respondents. The study aimed to develop a scale (UECUBS) to determine the unethical computer use behavior. A factor analysis of the related items revealed that the factors were can be divided under five headings; intellectual property, social impact, safety and quality, net integrity and information integrity.     

A hybrid discrete particle swarm optimization for vehicle routing problem with simultaneous pickup and delivery

Vehicle routing problem (VRP) is an important and well-known combinatorial optimization problem encountered in many transport logistics and distribution systems. The VRP has several variants depending on tasks performed and on some restrictions, such as time windows, multiple vehicles, backhauls, simultaneous delivery and pick-up, etc. In this paper, we consider vehicle routing problem with simultaneous pickup and delivery (VRPSPD). The VRPSPD deals with optimally integrating goods distribution and collection when there are no precedence restrictions on the order in which the operations must be performed. Since the VRPSPD is an NP-hard problem, we present a heuristic solution approach based on particle swarm optimization (PSO) in which a local search is performed by variable neighborhood descent algorithm (VND). Moreover, it implements an annealing-like strategy to preserve the swarm diversity. The effectiveness of the proposed PSO is investigated by an experiment conducted on benchmark problem instances available in the literature. The computational results indicate that the proposed algorithm competes with the heuristic approaches in the literature and improves several best known solutions.     

Who are problematic internet users? An investigation of the correlations between problematic internet use and shyness,loneliness, narcissism,aggression and self-perception

This study investigated correlations between university students’ problematic internet use behaviors and shyness, narcissism, loneliness, aggression and self-perception. The participants were 424 students attending seven different faculties of a public university in Turkey; 215 were female and 209 male. Student’s ages ranged between 17 and 23, with a mean of 18.69. The Problematic Internet Use Scale, Shyness Scale, Narcissistic Personality Inventory, UCLA Loneliness Scale, Aggression Questionnaire, Social Comparison Scale and a Personal Data Form were used for data collection. Correlation analysis results showed positive associations between problematic internet use and shyness and aggression. No statistically significant correlation was determined between problematic internet use and narcissism, loneliness or self-perception. The results demonstrate that individuals who are problematic users are shier and more aggressive. Shyness and aggression emerged as significant antecedent variables of problematic internet use. Suggestions are made for further studies in the light of these findings.     

Computational analysis of fouling by low energy surfaces

Fouling is a cost increasing problem for a variety of industries including aerospace, chemical, petroleum, and food. There have been studies on mitigation of fouling some of which recommend use of lower surface free energy materials, manufactured by different techniques, as an alternative to conventional materials. Although modeling of fouling for a given surface has been an area of interest; there is a lack in the models about correlating the surface free energy with deposit amount computationally. In this study, computational model, including the effect of surface energy and operational parameters, was proposed and validated to estimate amount of foulants deposits and rate of deposition. Towards this purpose, four coated surfaces (Microlube/PTFE, TM117P, AMC148, and CNT) were compared with stainless steel (SS316 as control) for flow rates of 3 and 10 g/s and inlet milk temperatures of 40 and 60 °C. The percent error for the decrease in outlet milk temperatures between the experimental data and computed results was between 2% and 18% except for CNT (29.2%). The calculations of deposit amount for each test case and the surfaces tested were in good agreement with the experiments, i.e., average percent difference values between measured and calculated values were from 11.1% to 38.1% (except CNT) with overall average of 21.5%.     

Improving energy efficiency through the design of the building envelope

Buildings, their surroundings and related enterprises produce more CO₂, generate more pollution, consume more energy, and waste more natural resources than any other human enterprise or industry. Moreover, considerable parts of these environmental impacts are the results of the lodging industry [1].     

Carbon nanowalls deposited by inductively coupled plasma enhanced chemical vapor deposition using aluminum acetylacetonate as precursor

Well aligned carbon nanowalls, a few nanometers thick, were fabricated by continuous flow of aluminum acetylacetonate (Al(acac)₃) without a catalyst, and independent of substrate material. The nanowalls were grown on Si, and steel substrates using inductively coupled plasma-enhanced chemical vapor deposition. Deposition parameters like flow of argon gas and substrate temperature were correlated with the growth of carbon nanowalls. For a high flow of argon carrier gas, an increased amount of aluminum in the film and a reduced lateral size of the carbon walls were found. The aluminum is present inside the carbon nanowall matrix in the form of well crystallized nanosized Al₄C₃ precipitates.     

Characterization and charge transfer mechanism of PIN–cdse nanocomposites

This paper reports structural, thermal, and temperature‐dependent dielectric properties of polyindole–cadmium selenide (PIN–CdSe) nanocomposites. PIN and its nanocomposites were synthesized via in situ chemical oxidative polymerization method. Samples were characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), scanning electron microscopy with energy dispersive X‐ray (SEM/EDX), atomic force microscope, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Dielectric properties were analyzed as a function of temperature. FT‐IR spectroscopy indicated that both N H and aromatic CC bonds were affected more by doping process. Significant structural differences were observed in XRD and SEM analyses of PIN and its nanocomposites. Both XRD and DSC measurements revealed that crystallinity of the PIN increases to a certain degree with increasing doping level. Thermogravimetric analysis showed that addition of CdSe decreased degradation temperature of the PIN. Conductivity measurements investigated by universal power law indicated that the charge transport mechanism of all the samples is consistent with correlated barrier hopping model. POLYM. COMPOS., 37:3057–3065, 2016. © 2015 Society of Plastics Engineers