Papers by Author: Ciprian Stamate

Abstract: IMAQ Vision includes a set of optimized functions for image processing (filtering and geometric transformations) and analysis of different areas of interest (perimeter, area, orientation, height, length and width). Also with this program, it may determine the edges of objects, distances and angles between the edges, an object can be searched based on its shape. Particle analysis provides the ability to count objects within the pharmaceutical or biological applications. Image calibration is done to give the user instead of the unit pixel measurements, in units such as millimeters, inches, microns. This paper aims to examine the pharmaceutical powder containing ketoprofen in order to determine the quality of the particles and if this are optimal for pharmaceutical applications. It aims to detect surface defects in the deposited layer such as cracks or clusters of particles that cause surface irregularity. IMAQ Vision by processing images, increase productivity, versatility and reproducibility also reducing manufacturing costs.

Abstract: This paper presents experimental analysis of the phenomenon of friction that occurs between two surfaces, one of polyethylene and other ceramics. Alumina ceramic is being recognized like a good biomaterial for its high strength and toughness. This ceramic, is used to manufacture the femoral head for arthroplasty of the hip joint in association with an ultra-high-molecular-weight polyethylene (uhmwpe) socket. Wear-resistant properties of uhmwpe were screened on two principally wear devices: first made by polyethylene – alumina-magnesia ceramic and the second by polyethylene – alumina-magnesia ceramic covered with polyvinyl alcohol (pva) layer. Sterile physiological saline is chosen as the lubricant fluid media. After hydration the pva layer provide lubricant properties. Depending on the lubricant medium, the friction coefficient (cof) of polyethylene and alumina-magnesia ceramic-pva counterfaces was about 0.38 (24 times low that polyethylene and alumina-magnesia ceramic counterfaces). Polyethylene friction coefficient in contact with alumina-magnesia ceramic was more susceptible in saline solution in which was about 0.46 compared with 0.016 on alumina-magnesia ceramic-pva. On the other hand, fluid environment shows a strong effect on polyethylene wear in contact with ceramic surfaces, increasing friction coefficient by ceramic hydration. The wear particles obtained in dried conditions are aglomerated and well individualized compared with lubricated conditions which are poorly individualized and with fine structure.

Abstract: Joint prosthesis involves the combination in the form of friction couplings of the different materials such as two metals, metal-polymer and polymer-ceramic. This paper aims to analyze the wear particles produced from the friction between two biomaterials: ultra hight molecular weight polyethylene ( uhmwpe ) and magnesium aluminosilicate ceramic. To obtain the wear particles using a tribometer cetr umt-2 type that can reproduce the wear phenomena of different biomaterials in different humidity conditions and at various speeds of movement. The tests were performed in dry and lubricated friction conditions using saline solution, the best imitating biological conditions. The movement is similar to the friction torques of the hip joint: a semicircular motion of the polymer piece on the circular surface of the ceramic piece. Movement speed chosen is 0.25 m/s. Wear particles obtained were isolated from biomaterial surfaces and studied using scanning electron microscope. The images obtained are analyzed, particle's dimensions are extracted and then imported into autocad can provide information about the shape, size and surface of the particles. In light of these facts, we can say the inflammatory risk of biomaterial particles. In conclusion, the biomaterial particles are very small and the inflammatory rick is reducing to minimum in lubricated conditions.

Abstract: The present paper aims to study the possibility to modify the properties of polyvinyl alcohol (pva) cryogels prepared in the presence of ketoprofen in order to replace the damaged articular cartilage. Articular cartilage is the most important part of articulation characterized by very low friction, high wear resistance, and poor regenerative qualities. Polyvinyl alcohol is a non-expensive polymer, versatile and adaptable to various needs, with exceptional properties such as water solubility, biocompatibility, non-toxicity and with capability to form hydrogels by chemical or physical methods. The aims of this paper are the synthesis, the physicochemical characterization and analysis of the tribological properties of pva cryogels for cartilage replacement and the introduction of new concept in medication by creating the cryogel like a controlled drug release system. The morphology of the cryogels, the interaction between the pva macromolecular chains and medicament has been studied by Scanning Electronic Microscopy. The gels swelling in physiologic ser have been monitored by gravimetric method in order to evidence the hydrophilic properties. The mechanical properties of the cryogels have been investigated by dynamic mechanical measurements. In conclusion, the biomaterial obtained provides good swelling properties, mechanical resistance and it is ideal for extended drug release implantable systems.

Abstract: This paper presents a theoretical method for simulation and three-dimensional reconstruction of the anatomical elements of the spine in order to achieve hydrogel disc prosthesis by 3D printing. For these simulations are used computed tomography (CT) scan image and AutoCAD reconstruction program, to provide high quality prediction of the 3D spine structures appearance and design the patient specific prosthesis model. After initial registration, the internal surface of L5, S1 vertebras and intervertebral disc at the lumbosacral spine region was individualized from the CT image. Then, the contour of the anatomic structures on the CT image was modified manually or adjusted automatically according to AutoCAD possibilities, to drive the volume simulation of vertebras and intervertebral disc. Three-dimensional simulations of the adjacent vertebrae, intervertebral disc and vertebral disc contact areas are used to achieve a customized prosthesis automatically by 3D printing method. This planning system is attractive and very useful to design personalized prosthesis and has potential for clinical practice to establishing the severity of spine disorders.

Abstract: This paper analyzes the tribological properties of a polymer prosthetic component, which was optimized by coating polymer layers containing medicinal substances. Polymer component is made of ultra high molecular weight polyethylene (uhmwpe) and is used in prosthetic hip replacement for acetabular cup with a metal component of cobalt-chromium alloy molybdenum. Polymer surface was covered with a layer of polyvinyl alcohol hydrogel superporos containing the drug substance ketoprofen-cyclodextrin complex. Studies consisted in evaluating drug substance release during 12 hours and tribological evaluation of polymer surface in simulated physiological conditions using cetr-umt-2 device.

Abstract: Rehabilitation of joints that underwent major surgery, involves reducing postoperative pain and inflammation. Many pharmaceutical product used in reducing joint pain are based on the extended-release technology and becoming increasingly important in research domain. The performance of extended-release matrix tablets is dependent on the solid dosage properties like matrix materials used, which are semi-synthetic polymer like hydroxypropyl methylcellulose (HPMC) and sodium carboxy methylcellulose (Na CMC). Depending on the properties of the polymer used, drug release from the tablets may be controlled by erosion mechanism and surface roughness. In a physiological environment, the release of drug from a solid dosage form requires a gradual erosion of solid shape with simultaneous change of surface roughness. This paper presents the influence of surface erosion of solid dosage forms on the surface roughness and the release of the analgesic and anti-inflammatory substances in a biological environment similar to the human digestive juice.

Abstract: In this paper, the mechanical properties of extended drug release systems were studied. A binder is a material that is added to a formulation in order to improve the mechanical strength of a drug release system. The drug release systems investigated were cylindrical tablets containing mixtures of various ketoprofen types and binders. Among the binders used were a series of different molecular weights of kollidon va 64, carbopol 971 pnf, hydroxypropyl methyl cellulose and sodium carboxyl methyl cellulose. The samples were made in the form of cylindrical tablet of about 9 mm in diameter and containing different mixtures of drug substances and excipients in three formulations. Mechanical parameters such as hardness, tensile stress and friability were studied in order to determine how they are influenced by binder and how it influences wetting and disintegration of tables.

Abstract: Since, anti-inflamatory drugs have a high demand due to increased incidence of pain associated with different pathology; the objectives of this paper are the synthesis, the physicochemical characterization and analysis of the tribological properties for the ketoprofen-cyclodextrin complexes. The analysis of solubility for these complexes was carried out using MathCAD software. Tribological factors were evaluated by the wear resistance of cylindrical tablets containing ketoprofen-cyclodextrin complex, methocel and magnesium stearate. The tablets with ketoprofen-cyclodextrin complexes provide good solubility and wear resistance and these are ideal for preparation of extended release systems like implantable tablets or for orally administration tablets.