Improving Performance and Applicability of Green Composite Materials by Hybridization

The growing concern over environmental issues and the common interest to find a viable alternative to the use of glass or carbon composites reinforced has led to an increased attention about ecologically sustainable polymer composites. These \u201cgreen\u201d materials are made by natural fibers as reinforce, filled with natural-organic fillers, hence derived from renewable or biodegradable sources. At the same time, this relatively new class of materials faces several limits in comparison to traditional composites especially regarding the proprieties of resistance. This paper investigates the advantages on use a combination of natural fibers for improving the mechanical proprieties of \u201cgreen\u201d composite materials. At the moment, the common opinion is that green composites are not usable in structural applications, and, as consequence, have to be relegated to unworthy applications (as fillers). On the contrary, there are several evidences that mixing different natural fibers (in a practice usually called as \u201chybridization\u201d) leads to increase these material proprieties. Even if usually quite limited in term of percentage, from time to time these improvements permit a net enlargement in the fields of applications for green composites. Following a large State of Arts on green composites, including potential benefits and limits of these materials, the paper proposes several examples of hybridization showing its effect on mechanical proprieties

Drug treatment of vertigo in neurological disorders

ABSTRACTVertigo is a common symptom in everyday clinical practice. The treatment depends on the specific etiology. Vertigo maybe secondary to inner ear pathology, or any existing brainstem or cerebellar lesion but may also be psychogenic. Centralvertigo is a consequence of a central nervous system lesion. It is often associated with a focal neurological deficit. Peripheralvertigo is secondary to dysfunction of the peripheral vestibular system and is usually characterized by an acute vertigo withloss of balance, sensation of spinning in the space or around self, and is exaggerated with changes of the head and bodyposition; no other neurological deficit is present. Some medications may also cause vertigo. Depending on the cause ofthe vertigo, drugs with different mechanisms of action, physical therapy, psychotherapy, as well as surgery may be usedto combat this disabling malady. Symptomatic treatment has a particularly important role, regardless of the etiology ofvertigo. We reviewed the current medications recommended for patients with vertigo, their mechanisms of action and theirmost frequent side effect

The influence of variable operating conditions on the design and exploitation of fly ash pneumatic transport systems in thermal power plants

The efficiency of an air-slide pneumatic conveying system depends, first of all, on several basic elements chosen or calculated during the design of a plant: air-slide design parameters, air mover characteristics, as well as the physical and chemical properties of the material to be transported. However, during the exploitation of this type of system which is used for handling ash in thermal-power plants, either gradual and/or sudden changes in the operating conditions can arise. This may be due to changes both in the proportion of ash content, and in the flow characteristics of the porous membrane. The consequences of changes in these conditions on the performance of the ash handling system are analyzed, based upon the results of the experimental work carried out on the test rig at the Faculty of Mechanical Engineering in Belgrade, and upon the on-site measurements at the thermal-power plant "Nikola Tesla B"

Role of oscillatory shear index in predicting the occurrence and development of plaque

The paper presents theoretical basis and results obtained by calculation of blood flow in coronary artery bifurcation, whereby the emphasis is placed on the plaque occurrence analysis based on oscillatory shear index (OSI). OSI is the temporal fluctuation of low and high average shear stress. The endothelial or wall shear stress is a major factor that affects the formation of plaque phenomenon. There are complex hemodynamic conditions in these areas where local fluid flow dictates the occurrence and development of plaque. Favorable conditions for the plaque development occurring in areas characterized by low shear stress, while areas with higher values of OSI index are not susceptible. Arterial bifurcations are the places in vascular tree where atherosclerosis mainly occurs. OSI index response to the appearance of plaques in the common coronary artery and branches are considered on three out of eight possible combinations of plaque locations. Algorithm for the calculation of OSI index are embedded in software PAK-F and the results are written in FEMAP neutral and Paraview VTK file format

Original scientific paper

The effect of reversing current deposition on the apparent density of electrolytic copper powde

/PRIKAZ SLU^AJA 616.245-005.4-07-089 Rizi~ni faktori i hroni~ni ishemijski pankolitis

Ishemija zida debelog creva dovodi do lezija koje rezultuju entitetom poznatim kao ishemijski kolitis. Naj~e{}i uzroci akutne ili hroni~ne ishemije tkiva su vaskularni poreme}aji okluzivne ili neokluzivne geneze. Hroni~ni ishemijski kolitis se manifestuje nekrozom zida creva sa posledi~nom stenozom obolelog segmenta a klini~ki se ispoljava pove}anim brojem krvavih stolica i bolovima u trbuhu. Le~enje je po pravilu hirur{kom resekcijom zahva}enog segmenta koja spa{va ‘ivot bolesnika. Prikazan je slu~aj bolesnika sa hroni~nim ishemijskim pankolitisom koji je nastao kao posledica ateromatoznih promena ogranaka mezenterijalnih arterija multifaktorijalne geneze, gde su od zna~aja starije ‘ivotno doba (preko 60 godina), kardiovaskularne bolesti, hroni~n