Background and Aim: In patients with complete denture, some clinicians have used modelling plastic impression compound (MPIC) along tissue conditioner (TC) materials simultaneously. Little information is available on the composition of these materials and the interaction between them. The purpose of this study was to evaluate the influence of two components of MPIC on the structure and chemical composition of TC.Materials and Methods: In this experimental study, MPIC specimens were provided in 25×2 mm discs. Specimens were randomly divided into three groups and were immersed in ethanol 70%, plasticizer (dibutyl phthalate) and a mixture of them (ethanol 70% and dibutyl phthalate). All of the discs were weighed with a digital balance before and 2, 4, 6 and 24 hours after immersion. Values were analyzed by non parametric Kruskal-Wallis (a= 0.05) and SPSS 16 for Windows (SPSS Inc., Chicago, IL) was used for statistical analysis.Results: Statistical analysis indicated significant differences among all groups (p>.05).Conclusion: Dibutyl phthalate (DBP) had high impact on the solubility of MP, while the mixture of dibutyl phthalate (DBP) and ethanol demonstrated the highest impact.

The purpose of this study was to evaluate the effects of nano-clay particles and oxidized polypropylene as a compatibilizer on the decay resistance of wood plastic composite and compare it to Coriolus versicolor fungi. In order to provide oxidized polypropylene as the compatibilizer, polypropylene was oxidized in the presence of air oxygen for 2 hr by an internal mixer. Afterwards, wood fibers, polypropylene, nano-clay particles and oxidized polypropylene as a compatibilizer in a certain ratio were mixed in an internal mixer and pressed into plates of 150´150´2 mm3 nominal dimensions using a laboratory hydraulic hot press. Then, the decay test was carried out using a white rot fungus such as Coriolus versicolor. Results showed that the weight loss of composite due to decay was proportional to the nano-clay particle percentage, so that increasing the percentage of nano-clay particles from 0% to 4% was associated with less weight loss and decay. In addition, the samples without a compatibilizer showed more weight loss and decaythan those having a compatibilizer. Morphology of the composites containing nano-clay particles were evaluated by using X-ray diffraction and transmission electron microscopy, results demonstrated that the distribution of Nano-clay particles in the field of the polymer was an intercalation type. This indicated the better stability of this class of composites compared to Coriolus versicolor fungi.

Background. In recent years, plastic waste and residuals in different ecosystems have been introduced as serious challenges. Plastics with different chemical structures and derivatives are extensively applied for the packing of foods, pharmaceutical products, cosmetics, and the like. Due to distinct polymeric backbones, plastics are highly resistant to thermooxidative, irradiation degradation, and mechanical stress, resulting in inadequate recycling and accumulation in the environment. These features make plastics threatening pollutants for humans and other living organisms. Simultaneous application of plasticizers and other components during the production of plastics can increase these toxic effects. Methods. Here, the content and data related to plastic particles toxicity on cardiovascular system indexed in PubMed, Scopus, and Web of Science. Results. Data have indicated that plastic nanoparticles/microparticles induce several pathological conditions following their entry into the body via cutaneous tissue, gastrointestinal ingestion, and inhalation. Plastic particles use different mechanisms to stimulate cytotoxicity and genotoxicity in several organs. The cardiovascular system and mainly endothelial cells are in close contact with circulating plastic particles and subsequent injuries. Endothelial cell cytotoxicity induced by plastic derivatives via different molecular mechanisms was discussed in this review article. The reduction of viability (either autophagy or apoptotic death), mitochondrial injury, oxidative stress, disruption of cell-to-cell integrity, and the like are the main underlying mechanisms in the presence of plastic particles. Conclusion. These findings help us understand the vascular tissue injury induced by plastic nanoparticles and microparticles and develop preventive and therapeutic approaches. Practical Implications. Understanding the mechanisms by which plastic particles can exert toxic effects on biological systems, especially the cardiovascular system, is helpful in the prediction of related injuries and pathologies.

Plastic hinge properties play a crucial role in predicting the nonlinear response of structural elements. The plastic hinge region of reinforced concrete normal beams has been previously studied experimentally and analytically. The main objective of this research is to evaluate the behavior of the plastic hinge region of reinforced concrete deep beams and its comparison with normal beams through finite element simulation. To do so, ten beams contain six deep beams, and four normal beams, under concentrated and uniformly distributed loading, are investigated. Lengths in the plastic hinge region involving curvature localization, rebar yielding, and concrete crushing zones are studied. The results indicate that the curvature localization zone is not suitable for the prediction of plastic hinge length in reinforced concrete deep beams. Based on the results it can be stated that in simply supported normal beams the concrete crushing zone is focused on the middle span, but in simply supported deep beams by creating a compression strut between loading place and support, the concrete crushing zone spreads along the compression trajectory. The rebar yielding zone of simply supported beams increases as the loading type is changed from the concentrated load at the middle to the uniformly distributed load.

In the present work, the ability of wood-plastic composite containing high density polyethylene and wood powder as a recycled material to remove methylene blue cation pigment was studied. The effect of some important parameters such as pH, adsorbent amount and contact time was investigated. Adsorption efficiencies for methylene blue were maximized at alkaline pH. Adsorption capacity increased with increasing adsorbent amount and contact time. The value of R2 in Langmuir model was equal to 1 and the separation factor for 0. 5 and 1 g of adsorbent was 0. 09 and 0. 1, respectively. Given that the methylene blue adsorption data were more consistent with the Langmuir isotherm model, it can be stated that the wood-plastic composite probably has uniform adsorption surfaces and the adsorption process occurred in a homogeneous system on the adsorbent surface. Based on the results of this study, it was observed that this composite is a suitable adsorbent for removing methylene blue from aqueous solutions and used as a purifying agent in the decolorization of effluents containing pigments. This adsorbent is recyclable and cost-effective for dye removal from textile industry wastewater.

The purpose of the research was to examine the effect of nano-clay particles and compatibilization of oxidized polypropylene in molten phase on the mechanical and physical properties of wood-plastic composite made from polypropylene and Phragmites ausralis flour. For this purpose, polypropylene in molten phase was oxidized in the vicinity of air oxygen and 1-dodecanol alcohol for 2 hours. Then Phragmites ausralis flour with the weight ratio of 50% and the polymer phase was mixed with the compatibilizer at two levels (0 and 3%) and nano-clay particles at three levels (0, 2, 4%) in an internal mixer for 6 min under the temperature of 165° C. Finally, the test specimens were prepared by using the hot press with the dimensions of 150×150×2 mm. The mechanical and physical properties including tensile and flexural modulus and strengths, Izod impact strength, long term water absorption and thickness swelling were examined according to ASTM standards. The results showed that the using oxidized polypropylene as compatibilizer improves all physical and mechanical properties of the composite. They also showed that increasing nano-clay particles, the physical and mechanical properties of the wood-plastic composite improve, except for the Izod impact strength. The structural studies of composite and the way the nanoparticles are distributed using x-ray diffraction spectroscopy and SEM images showed that the distribution of nano-clay particles in polymer matrix is of the type of intercalated structures.