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Properties and Structure of Microcrystalline Chitosan and Hydroxyapatite Composites  [PDF]
Luciano Pighinelli, Magdalena Kucharska
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2014, DOI: 10.4236/jbnb.2014.52015

The skeletal system in the human body is very important, provides support and gives shape to the body and provides a network between all soft tissues. The most common problems in hard tissues are bone fractures, defects or diseases which needed to be treated. The developments in artificial bone area seem to solve most of the hard tissue problems, on the other hand artificial bones themselves may cause other problems and in many cases they do not have sufficient mechanical properties and/or good biocompatibility. The importance of chitosan and its derivatives like microcrystalline chitosan has grown significantly over the last two decades due to its renewable and biodegradable source, and also because of the increase in the knowledge of its functionality in the technological and biomedical applications. The excellent biocompability, biofunctionality, and non-antigenic property make the chitosan and its derivatives as a microcrystalline chitosan an ideal material for tissue regeneration. To improve the suitability of chitosan for bone tissue engineering, the composites of MCCh and hydroxyapatite were studied. In the present work the characterization of the MCCh and composites with HAp in form of films and sponges, is based on physico-chemical tests, morphology, structure, particle size of HAp powder and distribution in the polymer matrix. The compositions with film and sponge shape are derived from the junction of two different materials, containing organic and inorganic substances. All sponge preparations, with HAp/MCCh have a well-shaped 3-dimensional structure, which could be used as implants in orthopedic surgery for a scaffolds base for medical applications.

Properties of Microcrystalline Chitosan-Calcium Phosphate Complex Composite  [PDF]
Luciano Pighinelli, Magdalena Kucharska
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2013, DOI: 10.4236/jbnb.2013.44A003

Nature itself uses materials like, cellulose to provide the structure of plants, chitin as the exoskeleton of several insects and molluscs, collagen for mechanical support in connective tissues and so on. At present, the socioeconomic situation of the modern world has raised the interest in renewable materials being used in regenerative medicine. The composition of MCCh/?-TCP complex in sponge shape is derived from the junction of two or more different materials, containing organic and inorganic materials, including bioactivity and biodegradability as a characteristic. The chemical characteristics of MCCh/?-TCP complex composites showed that both of the components organic and inorganic exist in the material. All sponge preparations, with MCCh/?-TCP have a well-shaped 3-dimentional structure, a highly porous and interconnected and homogenous pore structure to ensure a biological environment conducive to cell attachment and proliferation as well as tissue growth, providing the passage of nutrient flow. These materials can be used in future for medical applications as a base for scaffolds production and as implants in regenerative medicine.

Interaction of glassy fertilizers and Cd2+ ions in terms of soil pollution neutralization  [PDF]
Irena Wac?awska, Magdalena Szumera
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.38092
Abstract: Immobilization of cadmium contamination in soils by precipitation of nonassimilable for plants Cd-phosphates was considered. Glassy fertilizer of controlled release rate of the nutrients for plants as a source of phosphate anions was applied. The negative role of Cd complexing citric acid solution simulating the natural soil conditions, which inhibits the Cd-phos-phates formation, was stated.
Application of Survival Analysis in Studies of Human Ontogeny  [PDF]
Magdalena Kosińska, Anita Szwed
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.511162

The main goal of this work is to demonstrate the suitability of survival analysis for ontogenetic studies. The research material includes retrospective data of the age of the occurrence of ontogenetic events such as birth (N = 487), menarche (N = 2016) and menopause (N = 3597). In order to study the time of occurrence of ontogenetic events and to indicate the impact of environmental factors the survival analysis was applied. First, the percentiles of functions established for studied events were calculated. Next, the Kaplan-Meier survival curves were derived. In the last step theinfluence of environmental factors was established and the comparison of groups determined based on the chosen factors was performed. The delivery time shows that 14% of infants were bornpreterm. The risk of preterm delivery increases with the severity of factors disrupting pregnancy (from none to coexisting maternal and fetal risk factors) (\"\"; p < 0.001). In the case of menarche percentile positions indicate that the menarche occurs between the 12thand the 14thyear of life as the period in which most girls exceed the puberty threshold. The Cox’s proportional hazard model indicates that the time of menarche occurrence is significantly depended (\"\"; p < 0.001) on the place of the mother’s residence and number of children in the family (respectively p < 0.03 and p < 0.001). The time interval established for 50% occurrence of this experience was designated between the 49th and the 52nd years of life. The time of menopause occurrence is significantly depended on both of considered factors: the educational level and smoking cigarettes (\"\", p < 0.001). Survival analysis is suitable for studies of the distribution in time of developmental events. It can be used to indicate the factors which significantly influence the course of development by modifying the duration of developmental stages.

Chelation of Cu(II), Zn(II), and Fe(II) by Tannin Constituents of Selected Edible Nuts
Magdalena Karama?
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10125485
Abstract: The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II) and Zn(II) was determined by the reaction with tetramethylmurexide, whereas for Fe(II), ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II). The Fe(II) complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II) by ~90%. The capacity to chelate Zn(II) was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II), whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II) chelation took place at the levels tested.
Estudio palinológico de la Formación Punta del Barco, Cretácico Inferior (Aptiano) de la provincia de Santa Cruz, Argentina: Descripciones sistemáticas I: esporas monoletes y triletes lisas y cinguladas
Ameghiniana , 2008,
Abstract: smooth and cingulate trilete and monolete disperse spores from the punta del barco formation, lower cretaceous of santa cruz province are being described in this paper. the trilete spores belong to the genera biretisporites, deltoidospora, todisporites, cyathidites, densoisporites, foraminisporis, contignisporites, laevigatosporites and reticulosporis. the last genus is mentioned for the first time in argentina, and is one of the oldest known records. some of these taxa represent vegetal groups no reported for this taphoflora, enlarging therefore its previous knowledge.
La industria textil uruguaya (1900-1960)
Bertino, Magdalena;
América Latina en la historia económica , 2009,
Abstract: the uruguayan textile industry started in the early xxth century based on the production of woven fabric and wool spinning mill (tops). from the years of the 1929's crisis onwards, it went through a great expansion due to a protectionist policy based on favourable exchange rates. those were the times of the import substitutive industrialization (isi) in the country. after the second world war and, particularly, during the fifties it reached its height with the production of cotton fabrics and synthetic fibers. meanwhile, wool exports would grow strongly. however, in the late fifties, the isi strategy was in trouble and the obstacles for export's growth and the economic stagnation together with the removal of the protectionist's policies, put an end to the textile industry development. as a consequence, it experienced a deep crisis and lost importance both for the industry and for the economy as a whole.
Estudio palinológico de la Formación Punta del Barco, Cretácico Inferior (Aptiano) de la provincia de Santa Cruz, Argentina: Descripciones sistemáticas II: esporas triletes apiculadas, murornadas, tricrasadas y perinadas. Implicancias paleoecológicas
Ameghiniana , 2008,
Abstract: eighteen species of disperse trilete apiculate, murornate, tricrassate and perinate spores from the punta del barco formation, in the meseta baqueró area, lower cretaceous of santa cruz province, are described. they belong to the genera gleicheniidites, clavifera, ornamentifera, ceratosporites, concavissimisporites, staplinisporites, retitriletes and lygodiidites. besides, a new genus for a perisporate spore -capsispora- is proposed, an indeterminate apiculate form and two new species of the genus gleicheniidites, are described. finally, some paleoecological implications are given from the study of this spores association, which are related to stress conditions by the strong volcanic activity during the sedimentary deposition of this unit.
A distin??o entre representa??o de palavra e representa??o de coisa na obra freudiana: mudan?as teóricas e desdobramentos filosóficos
Arnao, Magdalena;
ágora: Estudos em Teoria Psicanalítica , 2008, DOI: 10.1590/S1516-14982008000200002
Abstract: the distinction word representation/thing representation in freud: theoretical changes and philosophical consequences. freud reintroduces the distinction thing representation/word representation in metapsychological works after it was used in 1891. this representational pair synthesizes, in 1915, a break both with the psychology of the time and with a long philosophical tradition. such break turns problematic many of the suppositions deeply rooted in today's philosophy. this article inquires about the significance of the division word/thing representation for psychoanalysis as well as for the representational philosophy, and it points out some of the most important effects of it.
Efectos del Barrio La Gloria: Experiencias del lugar y estrategias simbólicas de los sectores populares en el Gran Mendoza
Cuadernos de antropolog?-a social , 2011,
Abstract: in this article i search the transformations in urban space and the uses of the place by popular sectors and their organizations in the greater mendoza. housing policies and changes in the housing market have caused the suburbanization of the middle and popular classes and hierarchy of the territories during the last thirty years. in this work we study the case of barrio la gloria is located in the southeastern city of godoy cruz, an area characterized by the presence of classes. i describe the " experience of the place ", ie, how they live material and symbolic inequalities inhabitants of a crowded grand mendoza and analyze the strategies of organizations to accumulate symbolic capital in an area felt insecure by its inhabitants and qualified "dangerou s" by the press.
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