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A simple manufacturing method to obtain bent shape tubes with variable cross-section from fibre reinforced composites with application in high performance handlebars for mountain-bicycles was used. The original procedure is able to assure constant pressure upon the reinforcement material, the result being a compact composite, good quality with an optimum reinforcement degree. Tests and analytical computations, based on classical laminated plate theory delivered the engineering constants that have been used in the finite element simulations of two important safety tests for the handlebar (bending and torsion). The experimental results obtained for lateral bending test (critical test) are in agreement with the finite element simulations. Keywords: bicycle handlebar, composite parts, mechanical testing, finite element simulation

The paper deals with the research of variety of non-standard samples of plastic material made by injection moulding. The samples were made of conductive plastic material (LNP Stat-kon Compound ZX05009). Brown Corundum F24 was used for blasting under different pressures. This conductive plastic material can be applied as a plastic electrode, it is therefore possible to make measurements and examination of electrical conductivity. The experiment is used in order to establish the extent, to which the pressure used at blasting measurably affects the electrical conductivity of plastic electrode. Keywords: physico-mechanical properties, casting, plastic electrode, injection holding

The objective of this work was the modification of the pigment Yellow 17 structure through a treatment with ZnCl2 and Na2SiO3 in order to improve its properties. The modifications that appear in pigment structure were revealed by UV-visible diffuse reflectance and EDX analysis. The synthesized pigments were used to colour the polypropylene. The chromatic modifications appeared through pigment colouring with modified pigments were evaluated by measuring the colour intensity and colour difference. The light fastness and UV protection of the coloured polypropylene samples were also highlighted. Keywords: organic pigments, polypropylene, colour measurements, light fastness, UV-protection

The present paper aims to investigate the effect of surface defects upon contact area shape and dimensions in the case of metallic spherical punches pressed against a flat, optically transparent surface. Experimental investigations were conducted using a previously advanced, optical method, based on surface reflectivity. Various surface defects were artificially generated on the surface of steel ball bearing balls with 12.775 mm in diameter. The considered defects were grooves and holes. The employed experimental method is based on the accurate evaluation of contact interface reflectivity of loaded contacts, by aid of laser profilometry, as described in previous works [1-9]. Keywords: surface defects, mechanical contacts, contact area, laser profilometry, reflectivity

The aim of this study was to investigate the surface topography and to compare the calcium and phosphorus ions concentration in dentine and cement following their contact with five acidic drinks in the presence or absence of saliva. 25 caries free extracted teeth were used in this study. All the teeth were longitudinally sectioned in three slices. One slice has been stored in distilled water (control group). The second slice has been continuously immersed for 12 h in one of the tested beverages: Red Bull, Lipton Green Tea, a commercial apple juice, a natural carbonated mineral water and lemon juice. The third slice has been subject to 3 cycles of immersion in one of the tested beverages for 1 min, followed by storage in artificial saliva (AFNOR NF S90-701) for 4 h. The samples were analyzed using a scanning electron microscope and an EDX detector. The specimens continuously stored in acidic beverages showed enlarged dentinal tubules. The specimens successively stored in acidic beverages and saliva showed a slightly eroded surface of dentine and cement. The calcium and phosphorus ions concentration in dentine and cement significantly decreased following continuous storage in all the tested beverages (mean calcium ion concentration (wt%) in dentine (D)/cement (C): 28.17/23.93 control group, 16.45/11.07 apple juice, 22.84/11.48 Lipton Green Tea, 24.01/21.46 natural carbonated mineral water, 15.06/9.22 lemon juice, 18.09/10.52 Red Bull; mean phosphorus ion concentration (wt%) in D/C: 10.80/ 9.92 control group, 7.84/6.55 apple juice, 8.70/6.98 Lipton Green Tea, 9.39/9.21 natural carbonated mineral water, 7.45/6.28 lemon juice, 7.85/6.79 Red Bull). The decrease of mineral ions concentrations in dentine and cement was significantly lower when saliva has been used as a storage medium between immersions in acidic beverages (p < 0.05, ANOVA and Bonferroni test). Under the conditions of this study, saliva offered to dentine and cement a protective effect against the acidic challenge of tested beverages. Keywords: dentine, cement, acidic beverages, SEM, calcium ions, phosphorus ions

The aim of our study was to obtain cellulose acetate composites based on hydroxyapatite and nystatin with increased local therapeutic effect in the therapy of candidiasis. The porous composites were obtained by phase inversion method. Antifungal susceptibility of the samples was investigated by the Kirby Bauer Disk Diffusion test. The method has demonstrated an antifungal effect of the samples against Candida albicans as well as the fact that the polyene antibiotic nystatin might be an optimal choice as active agent incorporated in a composite. Also we have studied the swelling and the degradation of the membranes. These measurements help us better understand the water and PBS absorption capacity of the polymer matrix. Keywords: Composite, cellulose acetate, hydroxyapatite, nystatin, antifungal activity

This paper presents the results of the author’s latest researches on lignocellulosic basic structure composites, which resort to wood fibres and chips, in admixture with mineral binders - cement and gypsum. The obtained products, shaped as boards and blocks, may be deemed “ecological products” with applicability in the field of Civil Engineering, both as plating materials and as filling material (for the sandwich-type structures). The obtained results may be reckoned for the theoretical and experimental basis for further development of the materials and products achievable in industrial systems and usable in the structure of constructions for various purposes. Keywords: composites, wood chips, wood fibres, adhesiveness, embedding

The research highlights the main trends and guidance in the design of products using plastics in conditions of sustainable development of society. Plastics have an important role in the configuration of the new products still in the phase of conception. Having in view the main advantages of the utilization of plastics the expectation is to see an increase of the weighting of these ones in the products development. The present work spotlights the positive influence of the covering of the alloys with polyester. Especially it aims to increase the wearing resistance and resistance to fragility that has a direct effect on the increase of the functioning time in the total life cycle of the product. Keywords: polyester graphite, wear resistance

In the industry of plastics and dyes, pharmaceuticals and agriculture, the toxic effects of heavy metals have been reported during prolonged professional exposure. Heavy metals in the environment can enter the body orally, inhaled or by skin absorption. Unlike other toxins present in the environment, heavy metals accumulate in tissues because the body has no ability to remove them. Heavy metals in excess cause numerous metabolic imbalances. In cancer, heavy metal overload could be a stimulus for secretion of chemokines, for promoting oxidative stress and antioxidants inactivation, for altering cell signaling, for promotion and progression of tumorigenesis. Strategies to prevent accumulation of toxic metals, to decipher the pathophysiological mechanisms by which heavy metals affect cell metabolism, to increase excretion of toxic metals without removing essential minerals in the body is the subject of current researches. Keywords: heavy metals, dyes, plastics, skin cancer

Poly(ethylene terephthalate) PET was subject to a glycolysis process using diethylene glycol (PET/DEG = 1/1 molar ratio) and zinc acetate as trans-esterification catalyst. An unsaturated polyester resin was then prepared using the glycolysis product and maleic anhydride. The molecular weights of glycolysed PET products and polyester resin were investigated using gel permeation chromatography (GPC) analysis. A cross-linking reaction of the unsaturated polyester resin was performed in the presence of styrene (different amounts) at 80°C. The compression and impact strength/resistance properties of the cured resins were determined. Keywords: PET waste, glycolysis, GPC, unsaturated polyester resin, mechanical properties