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In this study, a new solution for the development of an antiradar camouflage by overlaying several mono-pigment polymeric structures in a composite structure is provided. In this respect, powder materials with antiradar properties (carbon nanotubes, graphite, active charcoal, aluminum trioxide) were embedded in polymeric matrices. The performances of the developed products were tested using an experimental device for the measurement of electromagnetic efficiency within the frequency range from 1 to 18 GHz.

Lately, PP-R pipes have become increasingly popular in terms of drinking water installations and heating. Comparated to the classic pipes from copper or steel, pipes from propylene are much easier to use, they have obvious qualities and they are marketed at a much lower price. The study aims a comparative analysis of the physical-mechanical properties of the four most common types of pipes from propylene, which are currently found in commerce : simple without insertion(PP-R), with insert of composite fiber (PP-R-CF), with insert of basalt fiber (PP-R-BF) and with insert of aluminium (PP-R-AIF). Experimental research showed that from the point of view of thermal expansion, the best behavior is from the pipes from propylene without any insert and the value of the thermal expansion coefficient for the reinforcement pipe with basaltic fiber is very small. After these attempts at tensile, it resulted that all four samples which were analyzed from the point of view of the tensile strength, don’t exceed the limit that was given by the manufacturer (10-30 MPa), the values obtained being: for pipe from polypropylene of 17 MPa, for pipe from polypropylene with insert of aluminium of 18 MPa, for the test tube from pipe of polypropylene with insert of basalt fiber of 29 MPa and for the test tube from pipe of polypropylene with insert of composite fiber of 30 MPa. Therefore, from the point of view of the behavior at tensile and bending, the best behavior is from the pipes from polypropylene with insert of basalt fiber and pipes from polypropylene with insert of composite fiber.

Background. The macroporous polyurethane ether foam was introduced in the medical field, as early as the 90 ties, for the Vacuum-assisted closure (V.A.C.) of a wound. We describe our experience after treating abdominal wound dehiscence in a group of elderly gynecological patients with NPWT (Negative Pressure Wound Therapy), using ether foam coated with a silver layer. We reviewed elderly patients chart data that underwent abdominal surgery complicated with wound dehiscence treated with VAC for eighteen months. In all patients, the system used was the standard GranuFoam Silver™ dressing (different extents), which was usually replaced every 48/72 h. A total of 15 consecutive female patients were included. The median age was 67.3 (58-71) years. Duration of VAC treatment was median 14.2 (11-34) days, and we saw an improvement in wound repair but also clearance of S.S.I. on the third day after applying V.A.C. Ulta™. Definitive secondary closure of the wound was obtained in all patients, as the infection’s site clearance. The abdominal VAC treatment with GranuFoam Silver™ dressing in patients with infected abdominal wound dehiscence is safe and has proper patient compliance. The latest evolution of the silver foam polyether dressing, in conjunction with NPWT therapy, offers a better antimicrobial effect and shorter healing stage.

Diabetes mellitus (DM) and cardiovascular diseases (CVD) represent worldwide, major health problems. Frequently, diabetic patients may require therapy with implantable intra-cardiac electronic devices. In this article, we analysed the complications related to the presence of polymer-coated electrodes leads occurred among 351 patients, carriers of implantable electronic intra-cardiac devices: permanent pacemakers (PPM), cardiac resynchronisation therapy (CRT) or implantable cardioverter-defibrillators (ICD). Of all these patients, 99 (28.20%) had type 2 DM (p=0.022), double than the prevalence of DM in the general population (11%). Only two patients with PPM and DM had fractures of electrodes leads and one was diagnosed with right heart infective endocarditis, but no non-diabetic patient developed any complications related to the presence of polymer coated electrodes leads.

The paper presents the manufacturing process of advanced composite wind turbine blades designed for an experimental counter rotating vertical wind turbine (CR-VAWT). An iterative approach was used to present the manufacturing process of turbine blades starting from presentation of the turbine structure and material description as well as all manufacturing process stages. Two types of turbine blades were successfully manufactured using metallic molds and a cost-effective manufacturing technology. Based on the turbine blades obtained it can be said that the selected manufacturing process showed good results, very similar with results expected in case of using advanced technologies (i.e. autoclave technology.

The aim of this in vitro study was to evaluate the characteristics of four commercial dental composites: two dual-curing luting resin cements and two indirect composites for crowns and bridges. The novelty of the study consists in the use of combined characterization methods for the investigated materials, namely: after maintaining the samples in the water/ artificial saliva, besides sorption, the surface degradation of the samples was observed after their immersion period; thereafter, the immersion medium was lyophilized and then the percentage of residual monomer found in the medium was determined by HPLC. After 44 days, small concentrations of monomers have been determined in the aqueous/saliva extracts. SEM images show that the samples from each class of material, with a higher content of inorganic filler, exhibit a larger erosion of the surfaces after contact with water compared to the other two samples that show a larger erosion of surfaces after contact with saliva than with water. The surface of the dual-curing resin cement with a higher content of inorganic filler is the smoothest from the samples exposed to saliva, instead the other resin cement is the roughest, as shown by AFM analysis. The overall observation reveals that the samples kept in saliva are rougher than the ones kept in water. Smooth surface materials of both classes of materials ( with a higher content of inorganic filler) have absorbed a higher amount of water / saliva compared to materials with a rougher surface.Water sorption in the composite resins is influenced by the hydrophilicity of the monomers, the nature and size of the inorganic filler particles, and the quality of the matrix / filler interface.

The main objective of the paper was to prepare eco-friendly chiral hydrogels from chitosan and betulinic aldehyde under ultrasonic radiation effect, targeting their use for enantiomeric separations. This strategy promoted the obtaining of the hydrogels by supramoleclar organization of the imine units bonding the betuline skeleton with chitosan into ordered clusteres, while not altering the physico-chemical properties of the reagents. FTIR, SEM, CD spectroscopy and POM techniques were used to prove the pelicularities of the hydrogelation mechanism under the ultrasonication. The stability of the hydrogels was investigated by monitoring the influence of the swelling in three media of diferent pH, by POM and CD. It was concluded that the chiral hydrogels prepared by ultrasonication are stable when the pH vary from acidic to basic, indicating the new synthetic approach as a valuable method to yield suitable materials for enatiomeric separations in medical field.

Polypropylene fiber is widely used as a reinforcing material in composite materials of various engineering projects, because it has high strength and corrosion resistance. In this study, with the purpose of examine the impact of discrete polypropylene fiber on frost resistance of cemented soil, cemented soil treated with polypropylene fiber is used as the research sample. Firstly, the impact of curing time, fiber content and length on the strength of cemented soil has been considered. And then, the frost resistance characteristics of cemented soil reinforced by polypropylene fiber with the content of 0.5% have been investigated. The results show that with the development of curing time, the strength of cemented soil increases logarithmically. By adding an appropriate amount of polypropylene fiber, the strength of the specimen may be improved. In this study, cemented soil reinforced by polypropylene fiber 0.1% in content and 3 mm in length has the best reinforcement effect. After 21 cycles of freezing and thawing processes, a sharp decline in strength of cemented soil without fiber, and the strength loss ratio is up to 45%. There are cracks in the specimens, and some of the specimens have broken off. Differently, after 21 freeze-thaw cycles, the strength of the cemented soil with fiber decreased less, and the strength loss ratios are between 1 and 13%, and there are only small cracks on the surface of specimens. The results show that adding discrete polypropylene fiber is a suitable method to prevent the generation and development of internal cracks in the cemented soil during freezing and thawing, thereby improving the frost resistance. These results can be used as a reference for the application of cemented soil reinforced with fiber in seasonal frozen regions.

By using molecular dynamics, this study evaluates and compares the diffusion coefficients of CH4, CO2, H2, N2 and O2 gas molecules through a polysulfone / carbon nanotube, polysulfone / graphene and polysulfone / carbon nanotube-graphene composite membranes. Mechanical properties of the composites were assessed by performing virtual traction tests and the Young’s moduli exhibits values between 2.59 GPa for polysulfone membrane and 3.87 GPa for polysulfone / carbon nanotube-graphene composite membrane. The latter is found to exhibit superior permeability and mechanical properties, making it a promising device for gas separation.

Two different polyimide structures were synthesized by two-step polycondensation reaction in solution, in the first step using equimolar amounts of one of two aromatic diamine (DDM or MMDA) and one dianhydride (6HDA) in N,N-dimethylacetamide (DMAc) to obtain the poly(amic acids), followed in the second step by thermal imidization. In order to obtain novel polyimide/metal nano hybrid materials, conductive Ni/Cu nanoparticles were embedded on polyimide substrates, using laser ablation technique. The morphology of the resulted thin metal layers was investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results highlighted different surface characteristics of the auto-organized metallic/polymer nanoparticles, depending on the chemical structure of the polyimide substrate, the parameters of the laser ablation setup, the deposition time, the type of the metallic target. The obtained features of these polyimide/metal nano hybrid materials can be employed as an indicator of the possibility of using them for potential applications as conductive circuits or substrates for adhesion control.