Browsing by Author "Georgiev K."

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    Gas chromatography-mass spectrometry for characterization of liquid products from pyrolysis of municipal waste and spent tyres
    (2015-12-01) Pavlova A.; Stratiev D.; Mitkova M.; Stanulov K.; Dishovsky N.; Georgiev K.
    Liquid products produced from two different types of waste pyrolysismunicipal wastes and spent tyre wastes are investigated using gas chromatography- mass spectrometry. This method has been applied for detailed identification of composition of the samples. The components were characterized in terms of their Kovts retention indices on a PONA capillary column. The obtained analytical data were successfully used for the characterization of the samples. More than three hundred compounds were detected. The liquid products were complex mixtures, composed mainly of C4-C12 compounds. The examination of the selected m/z values very clearly indicates the existence of the different groups of compounds. With a lot of olefins content (31.9%), followed by aromatics (20.0%), paraffins (17.3%), and naphthenes (7.5%), it is described as the liquid product from pyrolysis of municipal solid wastes. The aromatic compounds in liquid product from pyrolysis of spent tyre wastes have the highest concentration (33.5%), and they are followed by naphthenes (28.6%), olefins (19.2%), and paraffins compounds (7.0%). The present study has shown that the pyrolysis of municipal waste and spent tyres can be used as a means for reduction of environmental pollution and production of liquid product which could be used as a fuel source.
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    SYNTHESIS OF FLUORENATED ANALOGUES OF SELF-ASSEMBLING PEPTIDE P11-4 AND STUDY ON P11-4 THERAPEUTIC EFFECT ON ARTIFICIAL INITIAL ENAMEL LESIONS
    (2023-01-01) Uzunova I.; Dobrev I.; Danalev D.; Raycheva R.; Georgiev K.; Petrova S.; Nihtianova T.; Belcheva A.
    Treatment of artificial initial enamel lesions is a key process in the dental practice. Unfortunately, traditional methods are often not accepted well by the patients, especially by the children. In this reason the search for new more acceptable approaches is a long-sought approach. The selection of an appropriate and accurate protocol to treat white spot lesions as well as reliably monitoring of the lesion dynamics is crucial to avoid the need for further operative treatment. Herein, we report synthesis of two fluorinated analogues of the peptide P11-4 and creation of a protocol to compare the effect of self-assembling peptide P11-4 (CURODONT Repair) on artificial enamel lesions on smooth surfaces after pH-cycling in a bioreactor system. The assessment of the effect is done using surface microhardness investigation. A well working protocol for studying of therapeutic effect of peptides on artificial initial enamel lesions was created. The obtained experimental data reveals that the treatment of artificial lesions with self-assembling peptide P11-4 using a newly created protocol and selected methodology resulted in improved surface microhardness in the experimental group.