Репозиториум на ХТМУ-София
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Изследователското хранилище на университета е с отворен достъп и изследванията и научните резултати, включени тук, са избрани и депозирани от библиотеката, отделните университетски звена и изследователски центрове в ХТМУ-София.
Хранилището съдържа:
- електронни дисертации и научни публикации, включително статии, доклади от конференции, работни документи и някои изследователски монографии;
- материали и публикации, свързани с университета при изпълнение на научни проекти.
Предоставя се пълно текстово съдържание за всички научни публикации в хранилището и, когато е възможно, за електронни дисертации.
Отвореният достъп осигурява възможно най-широкото разпространение и въздействие на постигнатите резултати на научните колективи в ХТМУ и допринася за нарастващия обем от научноизследователска литература, свободно достъпна онлайн.
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Challenges in Petroleum Characterization—A Review
(MDPI AG, 2022-10-20) Ivelina Shishkova; Dicho Stratiev; Iliyan Venkov Kolev; Svetoslav Nenov; Dimitar Nedanovski; Krassimir Atanassov; Vitaly Ivanov; Simeon Ribagin
252 literature sources and about 5000 crude oil assays were reviewed in this work. The review has shown that the petroleum characterization can be classified in three categories: crude oil assay; SARA characterization; and molecular characterization. It was found that the range of petroleum property variation is so wide that the same crude oil property cannot be measured by the use of a single standard method. To the best of our knowledge for the first time the application of the additive rule to predict crude oil asphaltene content from that of the vacuum residue multiplied by the vacuum residue TBP yield was examined. It was also discovered that a strong linear relation between the contents of C5-, and C7-asphaltenes in crude oil and derived thereof vacuum residue fraction exists. The six parameter Weibull extreme function showed to best fit the TBP data of all crude oil types, allowing construction of a correct TBP curve and detection of measurement errors. A new SARA reconstitution approach is proposed to overcome the poor SARA analysis mass balance when crude oils with lower density are analyzed. The use of a chemometric approach with combination of spectroscopic data was found very helpful in extracting information about the composition of complex petroleum matrices consisting of a large number of components.
Компетентностен подход и иновации в образованието. Оценяване на резултати от обучението. Приложни аспекти във висшето инженерно технологично образование и средно професионално образование.
(ХТМУ-София, 2024-05-30) Трайкова-Пархоменко, Силвия
Учебникът запознава с концепцията за прилагане на компетентностния подход в обучението, за същността и значението му; за усъвършенстване на уменията за планиране на дейностите по учебния предмет/дисциплина; за прилагане на стратегии, дидактически технологии, методически похвати и форми за развиване на умения и компетентности относно процеса на оценяване на резултати от обучението. Разглежда педагогически аспекти на компетентностния подход в обучението и оценяване на резултати от обучението.
Учебникът е предназначен за обучение на студенти за придобиване на професионална квалификация „Учител“ при подготовката им по основна дисциплина от учебния план: „Компетентностен подход и иновации в обучението“ и свързаната с нея задължително избираема дисциплина „Лидерство и комуникативни умения“. В този смисъл той е предназначен за студенти/специализанти от хибридни специалности, какъвто характер има обучението за придобиване на професионална квалификация „Учител“ от студенти/специализанти в или с инженерна специалност.
Учебникът може да е от полза на педагогически специалисти и преподаватели по всички учебни предмети/дисциплини в средното (общо и професионално) и висшето образование, тъй като разглежда и изяснява система от базисни въпроси на теорията за прилагане на компетентностен подход в обучението и на оценяването на резултатите от него.
Представени са примери от реална академична среда в Химикотехнологичен и металургичен университет (ХТМУ), подходящи за прилагане при всеки процес на обучение за целите на професионален тип подготовка. Примерите от академични курсове кореспондират със създаване на среда за формиране и развитие на умения за прилагане на компетентностен подход и модели на обучение.
Self-Assembled Molecular Complexes of 1,10-Phenanthroline and 2-Aminobenzimidazoles: Synthesis, Structure Investigations, and Cytotoxic Properties
(MDPI AG, 2024-01-24) Kameliya Anichina; Nikolay Kaloyanov; Diana Zasheva; Rusi Rusew; Rositsa Nikolova; Denitsa Yancheva; Ventsislav Bakov; Nikolai Georgiev
Three new molecular complexes (phen)3(2-amino-Bz)2(H+)(BF4−)·3H2O 5, (phen)3(2-amino-5(6)-methyl-Bz)2(H+)(BF4−)·H2O 6, and (phen)(1-methyl-2-amino-Bz)(H+)(BF4−) 7, were prepared by self-assembly of 1,10-phenanthroline (phen) and various substituted 2-aminobenzimidazoles. Confirmation of their structures was established through spectroscopic methods and elemental analysis. The X-ray diffraction analysis revealed that the crystal structure of 7 is stabilized by the formation of hydrogen bonds and short contacts. In addition, the molecular geometry and electron structure of molecules 5 and 6 were theoretically evaluated using density functional theory (DFT) methods. According to the DFT B3LYP/6-311+G* calculations, the protonated benzimidazole (Bz) units act as NH hydrogen bond donors, binding two phenanthrolines and a BF4− ion. Non-protonated Bz unit form hydrogen bonds with the N-atoms of a third molecule phen. The molecular assembly is held together by π-π stacking between benzimidazole and phenanthroline rings, allowing for N-atoms to associate with water molecules. The complexes were tested in vitro for their tumor cell growth inhibitory effects on prostate (PC3), breast (MDA-MB-231 and MCF-7), and cervical (HeLa) cancer cell lines using MTT-dye reduction assay. The in vitro cytotoxicity analysis and spectrophotometric investigation in the presence of ct-DNA, showed that self-assembled molecules 5–7 are promising DNA-binding anticancer agents warranting further in-depth exploration.
Prediction of Molecular Weight of Petroleum Fluids by Empirical Correlations and Artificial Neuron Networks
(MDPI AG, 2023-01-31) Dicho Stratiev; Sotir Sotirov; Evdokia Sotirova; Svetoslav Nenov; Rosen Dinkov; Ivelina Shishkova; Iliyan Venkov Kolev; Dobromir Yordanov; Svetlin Vasilev; Krassimir Atanassov; Stanislav Simeonov; Georgi Nikolov Palichev
The exactitude of petroleum fluid molecular weight correlations affects significantly the precision of petroleum engineering calculations and can make process design and trouble-shooting inaccurate. Some of the methods in the literature to predict petroleum fluid molecular weight are used in commercial software process simulators. According to statements made in the literature, the correlations of Lee–Kesler and Twu are the most used in petroleum engineering, and the other methods do not exhibit any significant advantages over the Lee–Kesler and Twu correlations. In order to verify which of the proposed in the literature correlations are the most appropriate for petroleum fluids with molecular weight variation between 70 and 1685 g/mol, 430 data points for boiling point, specific gravity, and molecular weight of petroleum fluids and individual hydrocarbons were extracted from 17 literature sources. Besides the existing correlations in the literature, two different techniques, nonlinear regression and artificial neural network (ANN), were employed to model the molecular weight of the 430 petroleum fluid samples. It was found that the ANN model demonstrated the best accuracy of prediction with a relative standard error (RSE) of 7.2%, followed by the newly developed nonlinear regression correlation with an RSE of 10.9%. The best available molecular weight correlations in the literature were those of API (RSE = 12.4%), Goosens (RSE = 13.9%); and Riazi and Daubert (RSE = 15.2%). The well known molecular weight correlations of Lee–Kesler, and Twu, for the data set of 430 data points, exhibited RSEs of 26.5, and 30.3% respectively.
Characterization of Bulgarian Copper Mine Tailing as a Precursor for Obtaining Geopolymers
(MDPI AG, 2024-01-23) Darya Ilieva; Lyudmila Angelova; Temenuzhka Radoykova; Andriana Surleva; Georgi Chernev; Petrica Vizureanu; Dumitru Burduhos-Nergis; Andrei Sandu
Valorization of high-volume mine tailings could be achieved by the development of new geopolymers with a low CO2 footprint. Materials rich in aluminum and silicon with appropriate solubility in an alkaline medium can be used to obtain a geopolymer. This paper presents a study of copper mine tailings from Bulgaria as precursors for geopolymers. Particle size distribution, chemical and mineralogical composition, as well as alkaline reactivity, acidity and electroconductivity of aqueous slurry are studied. The heavy metal content and their mobility are studied by leaching tests. Sequential extraction was applied to determine the geochemical phase distribution of heavy metals. The studied samples were characterized by high alkalinity, which could favor the geopolymerization process. The water-soluble sulphates were less than 4%. The Si/Al ratio in mine tailing was found to be 3. The alkaline reactivity depended more so on the time of extraction than on the concentration of NaOH solution. The main part of the heavy metals was found in the residual fraction; hence, in high alkaline medium during the geopolymerization process, they will stay fixed. Thus, the obtained geopolymers could be expected to exert low environmental impact. The presented results revealed that studied copper mine tailing is a suitable precursor for geopolymerization.