Papers by Elena Dyulgerova
Fast Fashion industry is a great example of a market with similar products and similar target gro... more Fast Fashion industry is a great example of a market with similar products and similar target groups of customers where marketing plays a key role in the competition for market share. In the era of Web 2.0. and Social Media boom businesses are facing a rise in customers’ forces and its pressure by influencing corporate communications and marketing campaigns. Ordinary people turn to influentials who reach broad consumer audiences and often have an impact on the decision-making-processes. In this way, brands are less protected by PR and advertising tools, as well as more vulnerable. Therefore, understanding the current communication environment and in particular how, when, where and who interferes with corporate image is important from managerial point of view and what strategy to be deployed. For these reasons, the thesis focuses on multichannel marketing in order to provide an understanding of how businesses have been connecting to people and then it continues with exploration of social media and the blogosphere as ways consumers have been complicating and influencing channels. In the end, it has been concluded that Social Media and the phenomenon of Blogosphere has led to the appearance of new self-made opinion leaders who tend to influence consumer behavior and respectively company’s reputation and brands’ image. On the other hand, it has been observed this can be positive for businesses since it provides relatively useful market information which could be helpful for marketing and communications managers by enabling them to observe their target groups in a more efficient ways. In the pursue of findings, the thesis includes primary research with two interviews with a bloggers and a fashion brand affiliate person, and secondary research covering literature review on relevant topics.
Calcified tissue research, Dec 1, 1976
Caries incipiens is associated with the dissolution of enamel by organic acids which are either p... more Caries incipiens is associated with the dissolution of enamel by organic acids which are either produced during digestion of food in the mouth or are present in the dental plaque. (Muller, 1905; Jenkins, 1965; Kleinberg, 1970, 1974). Understanding of the mechanisms by which enamel is dissolved is important for the treatment of caries incipiens. Recent investigations show that the dissolution of dental mineral, which is largely composed of hydroxyapatite, is controlled by diffusion mass-transport processes (
Applied Sciences
Knowledge of dental anatomy and the three-dimensional principles of debridement, sterilization an... more Knowledge of dental anatomy and the three-dimensional principles of debridement, sterilization and obturation is necessary for effective root canal treatment. The chemo–mechanical preparation of the root canal biomechanically significantly reduces the number of microorganisms present. However, research has demonstrated that microorganisms frequently persist. The antimicrobial effect of the irrigants is essential to their biological function. Several obturation techniques are currently available, the selection of which depends on the canal’s morphology and the individual therapeutic goals of each instance. New sealing materials and methods for regenerative root canal obturation are enhancing and improving the predictability of three-dimensional (3D) sealing procedures. Epoxy sealers and gutta-percha are currently employed by clinicians as the gold standard in obturation procedures. The most recent developments in endodontic sealing materials are related to bioceramic sealers. Reports...
Journal of Materials Science: Materials in Medicine, 2011
Journal of IMAB, Mar 26, 2010
Introduction: Typical chronic apical periodontitis is generally accompanied by periapical bone de... more Introduction: Typical chronic apical periodontitis is generally accompanied by periapical bone destruction, which is radiographically observed as periapical radiolucency around the apex. Pathological events in apical periodontitis are mainly characterized by bone destruction and this bone destruction is mediated by osteoclasts which are multinuclear cells derived from macrophages. Although bone tissue possesses the capacity for regeneration, there are many pathological situations in which this capacity is not sufficient to stimulate and realize healing processes. The development of biphasic calcium phosphate ceramic for bone graft is one of the promising biomaterials for better control of the complex processes of bone healing and regeneration. Materials and Ìethods: The subject of this study were seven clinical cases (seven patients-4 female and 3 male in ages from 22-53 years) with radiolucency and radiographical evidence of periapical lesions. The result of this treatment was presented in three groups: I) three of root canals were aseptically instrumented to ISO size 60 (# 11, 46, 21), II) two of them-to ISO size 70 (# 11,36), and III) the third group to ISO size 80 (# 21,22) (Fig.2). Following the ideology of the injectable implant material [37], this study used as, scaffold fine powder particles of biphase calcium phosphate ceramic mixed with saline solution. Results: The results of this study are presented in the radiographs listed as Fig. 5, 9, 10 preoperatively and Fig. 6, 7, 8, 11, 12, 13 and 14 postoperatively. The sequence of replacement of radiolucency with a radioopacity in periapex should be considered as one of the characteristics in remodeling of the processes after treatment. These findings showed that in a lapse of time the healing processes involve immature bone and fibrous connective tissues. Discussion: Our positive results are insufficient for suggesting any possible mechanisms expanding healing processes of lesions. But having in mind some data from the literature on bone regeneration, molecular and cellular interaction with calcium phosphate ceramics, it should be mentioned that some results have demonstrated that microporosity and surface activity of ceramic is responsible
International Journal of Peptide Research and Therapeutics, 2020
The biomimetic approach for enamel remineralization is a new, modern alternative in the treatment... more The biomimetic approach for enamel remineralization is a new, modern alternative in the treatment of early stages of caries. The development of novel biomaterials requires understanding of the protein-mediated processes of enamel biomineralization. One of the materials used for enamel regeneration is self-assembling peptide P 11-4. When it is applied to the carious lesion, the peptide undergoes one-dimensional self-assembly, including formation of nanotapes, ribbons, fibrils and fibers. As a result of this process a biomimetic scaffold within the initial enamel caries lesion is produced, supporting the natural remineralization driven by saliva. The peptide was originally developed for initial carious lesions, but the results show it has remineralizing effect even in deeper subsurface lesions. A series of in vitro and in vivo studies revealed the peptide's ability to induce crystal nucleation and growth in demineralized and eroded enamel. Although P 11-4 has been commercially available for almost one decade, further studies are needed to confirm its efficacy.
European Polymer Journal, 2019
Novel hybrid chitosan/calcium phosphates microgels for remineralization of demineralized enamel-a... more Novel hybrid chitosan/calcium phosphates microgels for remineralization of demineralized enamel-a model study,
Healing of standardized critical-size calvarial defects in rats was performed with nano composite... more Healing of standardized critical-size calvarial defects in rats was performed with nano composite material of nano-hydroxyapatite/3 % solution of chitosan in citric acid, and electrospinning fibres of poly lactic acid. Histologically at the 84 day, the implanted rats exhibited full closure of the defect by new developed connective and osteoid tissues penetrating in reticular pattern within the implant components. These results indicate that by using a newly created composite paste critical cranial defects can be successfully retrieved and probably is also suitable for other cases in bone augmentation surgeries.
Ceramics International, 2018
Samples of sintered biphasic calcium phosphates hydroxyapatite-Ca 10 (PO 4) 6 (OH) 2 and β-trical... more Samples of sintered biphasic calcium phosphates hydroxyapatite-Ca 10 (PO 4) 6 (OH) 2 and β-tricalcium phosphate-Ca 3 (PO 4) 2 subjected to high energy dry milling for different durations are studied by powder X-ray diffraction analysis. The Rietveld method as implemented in the FullProf program was applied in order to determine the quantities of the resulting crystalline phases and amorphous substance at each stage of the mechanical treatment. Microstructural analysis using appropriate size and strain models was performed in order to handle the distinct anisotropy observed in certain crystallographic directions for the hydroxyapatite and the results are presented in terms of crystallite size and strain evolution of the involved compounds. An interesting phenomenon of crystalline domains size enlargement of the hydroxyapatite phase upon prolonged milling duration was registered and discussed in the light of the up-to-date views and theories on crystal growth of nanocrystalline materials.
Diffuse reflectance infrared Fourier transform and Raman spectroscopy is applied to investigate t... more Diffuse reflectance infrared Fourier transform and Raman spectroscopy is applied to investigate the structure of hydrolyzed CaHPO4 · 2H2O (DCPD) processed to non-stoichiometric apatite to be used as starting material for preparing sintered calcium phosphate materials. The spectra of hydrolyzed DCPD samples, obtained under differing experimental conditions, are analyzed to check how the sintered phase composition correlates with the structure
Journal of IMAB - Annual Proceeding (Scientific Papers), 2010
Introduction: Typical chronic apical periodontitis is generally accompanied by periapical bone de... more Introduction: Typical chronic apical periodontitis is generally accompanied by periapical bone destruction, which is radiographically observed as periapical radiolucency around the apex. Pathological events in apical periodontitis are mainly characterized by bone destruction and this bone destruction is mediated by osteoclasts which are multinuclear cells derived from macrophages. Although bone tissue possesses the capacity for regeneration, there are many pathological situations in which this capacity is not sufficient to stimulate and realize healing processes. The development of biphasic calcium phosphate ceramic for bone graft is one of the promising biomaterials for better control of the complex processes of bone healing and regeneration.
Materials Letters, 1992
Biphase Ca-P bioceramics were sterilized in three ways -heated at 200°C for 40 mitt, autoclaved a... more Biphase Ca-P bioceramics were sterilized in three ways -heated at 200°C for 40 mitt, autoclaved at 120°C and y-radiated using intensity of 2, 2.5 and 3 Mrad and were studied using quantitative powder X-ray diffraction. The phase reaction mechanisms on the surface during sterilization were quantified. For reaching phase stability, at least 2.5 Mrad y-sterilization treatment or a minimum of 2 10 min duration of autoclaving at 120°C are needed.
Materials Letters, 2001
. Ž A complex of chemical, powder X-ray diffraction XRD , scanning and transmission electron micr... more . Ž A complex of chemical, powder X-ray diffraction XRD , scanning and transmission electron microscopic SEM and . Ž . TEM methods is specified for a controlled preparation of calcium-phosphate Ca-P biphase ceramics for the needs of the clinical practice to be used as bone implants. Reproducibility in the synthesis of hydroxyapatiteq alpha-tertiary calcium Ž . Ž . phosphate HAP q a-TCP and hydroxyapatiteq beta-tertiary calcium phosphate HAP q b-TCP bioceramics is achieved Ž . under controlled conditions: the calcium-to-phosphorus CarP ratio, the phases contents, and the texture of the sintered material. q
Journal of Materials Science: Materials in Medicine, 2010
The biomimetic synthesis and phase transformation of XRD amorphous calcium phosphate were studied... more The biomimetic synthesis and phase transformation of XRD amorphous calcium phosphate were studied by application of kinetic, chemical and spectral (XRD and IR) methods and thermodynamic simulations. Two SBFs (SBFc and SBFr), differing in their HCO 3 and Clion contents, were used in the maturation studies. It has been proven that the biomimetic maturation accelerated the phase transformation of less thermodynamically stable amorphous calcium phosphate to poorly crystalline hydroxyapatite. Several regularities have been found: (i) kinetic reasons determined the biomimetic precipitation of XRDamorphous calcium deficient phosphate (ACP); (ii) the precipitated ACP always contained impurities due to coprecipitation, ion substitution and incorporation phenomena; (iii) the increased content of HCO 3 ions in the surrounding microenvironments increased the rate of phase transformation and the concentration of MeHCO 3 ? (Me = Ca, Mg) species in the solution, but the solubility of CaCO 3 has only been decreased and its precipitation accelerated, thus playing a crucial role in the process under study.
Advances in Applied Ceramics, 2013
ABSTRACT
Journal of Biomedical Materials Research, 2001
Based on well-documented data showing that bioactive ions (such as Ca2+, PO4-, etc.) released by ... more Based on well-documented data showing that bioactive ions (such as Ca2+, PO4-, etc.) released by BCPC induce various cell responses and on the significance of herpes outbreaks in human pathology, we investigated whether BCPC can modify cell response to HSV-1 infection. The roles of some physical and chemical properties of ceramics were evaluated using three BCPC samples--French commercial macro-microporous (FR) and two Bulgarian microporous laboratory samples--one of which was modified with magnesium (BG and BG + Mg). Samples only washed in 0.9% NaCl were designated as nonconditioned while those resuspended in cell growth medium for 10 days after washing were designated as conditioned. Experiments were done on cells from the continuous MDBK line precultured on BCPC surfaces for different time intervals and thereafter HSV-1 infected. The yield of infectious virus progeny, measured as virus titers, was the parameter used to determine the cell response to HSV-1 infection mediated by BCPC as compared to that of the virus control, that is, virus yield in cells cultured without BCPC. The data obtained show that all three nonconditioned BCPC samples were able to modify cells to resist HSV-1 infection. The prolongation of the resistant state depended on the specific physical and chemical properties of the particular BCPC sample: as the data show that the conditioning procedure (1) increased the ability of BG + Mg to promote cell resistance, and (2) reduced the ability of FR samples to modify cells to resist HSV-1 infection. The data obtained show that apart from Ca2+ and PO4-, ions of biometals such as Mg2+ also are responsible for the induction and maintenance of cell resistance to HSV-1 infection.
Journal of Biomedical Materials Research, 1996
An in vitro study of the influence of Biphase Calcium Phosphate Ceramics (BCPCs) on bacterial str... more An in vitro study of the influence of Biphase Calcium Phosphate Ceramics (BCPCs) on bacterial strains is presented. The test procedures were carried out in saline test solution to which different quantities (2,4,50,100, and 200 mg) of BCPCs(samples A and B) were added. The influence of BCPCs on standard bacterial strains has been determined by measuring bacterial contamination using the plate count method. The testing method was validated with membrane filtration and direct inoculation in culture media of sediment and supernatant. The test demonstrated reduction of the bacterial cell population in from 1 to 24 h in all experiments. The antibacterial effect revealed the specific inherent properties of the BCPCs under investigation.
Journal of Biomedical Materials Research, 1996
An in vitro study of the influence of Biphase Calcium Phosphate Ceramics (BCPCs) on bacterial str... more An in vitro study of the influence of Biphase Calcium Phosphate Ceramics (BCPCs) on bacterial strains is presented. The test procedures were carried out in saline test solution to which different quantities (2,4,50,100, and 200 mg) of BCPCs(samples A and B) were added. The influence of BCPCs on standard bacterial strains has been determined by measuring bacterial contamination using the plate count method. The testing method was validated with membrane filtration and direct inoculation in culture media of sediment and supernatant. The test demonstrated reduction of the bacterial cell population in from 1 to 24 h in all experiments. The antibacterial effect revealed the specific inherent properties of the BCPCs under investigation.
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Papers by Elena Dyulgerova