bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the online learning response to predict students’ satisfaction
Authors: Sulisworo Dwi , Wulandari Yosi , Effendi Muh Saeful , Alias Mazni
Published: February 2021

Online learning is carried out as an effort to utilize information technology available in higher education institutions in anticipation of changes in the educational environment. Using appropriate technology in learning management is believed to be a drive to improve learning performance particularly in literary learning. This study aims to reveal and describe the implementation of online learning. The data was obtained based on student responses. The results of this study will be the basis for improving online learning management. This research is a qualitative descriptive study involving 42 students as respondents. There are 9 questions to determine students’ understanding and perception. The data in this research are processed qualitatively using the concept of Affinity diagram and Pareto diagram. From these diagrams, interpretation can be made by referring to the results of other researchers and relevant theories. The results of this study reveal that the main inhibiting factors in implementing online learning are the level of access to the internet, the low flexibility of the assignments submission deadline, ineffective feedback to students, and unclear instructions. In the LMS (Learning Management Systems) display, students find it is less attractive (the selection of appropriate themes of the display). However, with the online learning, the students felt that it potentially eases them in obtaining content and sending assignments/learning projects, and gives the flexibility of study time.
Building The Management System: Designs on the use of Blended Learning Environment
Authors: Musdalifah Musdalifah , Baharuddin Baharuddin , Jabri Umiyati , Elihami Elihami , Mustakim Mustakim
Published: February 2021

This study addressed the role of children in studying education is the use of education system. The goal of this study is to develop the international community-based research approach, which is a characteristic assessment involving non-participating observation, interviews and documentation. This research focuses on the models of teaching materials for training to use the full daily school system. The whole research focuses on the models of instructional media for learning through the use of a full day state education system. The data were analyzed to use a qualitative descriptive tool. The aim of data collection is to define teaching assessment by means of interview, review, assessment, documents and research instruments. Participants included 300 elementary school graduates, namely Sidenreng Rappang Regency, Enrekang Regency, Pinrang Regency, Barru Regency and Parepare City, South Sulawesi, Indonesia. The findings of the study showed no substantial associations between the introduction of a full day public education system, personal development, and a positive mindset. The researcher shall be allowed to examine the research questionnaire identified for this analysis and the field of activity research. On the other hand, the full days public school is substantially successful in the training program for elementary school children. Most of the functionality used in the originality of this research by the research instrument selected for the study are approved and used to understand the impact of mobile-based surveys on the character development to be significant predictors.
Analytical Effectiveness using Adobe Flash in Learning Energy Source at Primary School
Authors: Rostyawati Rima , Zulherman  , Bandarsyah Desvian
Published: February 2021

Information and communication technology in today’s world is developing so rapidly and bringing changes to all fields, especially in education. Learning innovations in education are carried out by teachers and students to get a fair learning process. This study aimed to determine the results of student acceptance in using interactive learning media using adobe flash on the energy source material used in the learning process in grade IV primary school. The research method used was quantitative methods with survey techniques and ADDIE development models. The initial stage of the media’s validity and feasibility test was carried out by three media experts, three material experts, and 5 class teachers from five different region schools. The number of samples in this study was 156 students from five different region schools. Data were taken using a questionnaire with a Likert scale of 1 to 5. Based on the data obtained, it showed the following values: (1) the average media expert test is (90.56%) including the criteria “Very Valid,” (2) the average material expert test score is (83.65%) including the criteria of “Very Valid,” (3) the average value of the product feasibility trial to grade IV teachers is (92%) including the “Very Valid,” and (4) the average value of product feasibility trials to users or grade IV students is (85.55%) including the criteria of “Very Good.” The conclusion was that interactive learning media using adobe flash on energy sources is very feasible and very well used in theme 9, “Kayanya Negeriku,” focusing on science lessons on energy sources in grade IV motivates students in learning. For the next research, the development model can be done in the future.
e-Learning Development on Basic Chemical Law Materials in Senior High School (SMA/MA) to Improve High Order Thinking Skill Ability
Authors: Afrianti Trayda , Zainul Rahadian
Published: February 2021

This research aims to develop e-learning for learning Chemistry, Law of Basic Chemistry, for Senior High Schools (SMA/MA). The method used is Borg and Gail. E-learning product development using the Moodle 3.75 application. The stage in the development of this research is the content and construct validity of the product being developed. The result obtained is an e-learning product of Basic Chemistry Laws which has very high content and construct validity. From the results of the content validation, it was obtained 0.98 each for Guidelines and information; 0.88 for Content / material; and 0.87 for Evaluation. From this section, it can be seen that the content validity has a very high interpretation. From the results of the construct validity includes guidance and information; Program Performance; and Systematics, Aesthetics and Design principles respectively 0.84; 0.84; and 0.76. This section looks very high, except for the systematic, aesthetic and design aspects which are still in the high category. These results conclude that e-learning products have very high validity to be used as learning materials for Chemistry in Senior High Schools (SMA) and Madrasah Aliyah (MA), especially in the material of Basic Chemistry Laws.
The modified drive of a metal-cutting machine with the V-belt transmission of increased resource
Authors: Krol O , Sokolov V , Tsankov P
Published: February 2021

The process of the design improving of the V-belt transmission for the metal-cutting machine drive according to the criterion of increased resource is considered. A three-dimensional modeling of the main motion drive structure for multi-operation machine was carried out using the applied library computer aided design KOMPAS-3D. A new approach to the parametric representation of the procedure for constructing a unified profile of a V-belt pulley based on the syntax of the APM WinMachine system is proposed. The idea of constructive change of the standard operating V-belt contour with the corresponding analytical apparatus, which provides increased drawbar power of the transmission, is proposed. Experimental researches on typical sections of V-belts, confirming the increase in the operation reliability of the belt drive have been carried out. provided that the cross-sectional area of the belt remains unchanged
Analysis of the possibilities for growing hedgehog head (Dactylis glomerata, L.) variety “Dabrava” on cinnamon forest soil. Vegetative development
Authors: Vateva Violeta
Published: February 2021

The soil and climatic conditions of the semi-mountainous regions are specific. One of the most important tasks in creating artificial grasslands for haymaking in such areas is the selection of suitable grass species. The aim of the experiment is to analyze the vegetative potential of hedgehog head from the variety “Dabrava” grow on cinnamon forest soil. To achieve this goal, a section of the foothills of Sakar Mountain was selected. The hedgehog head variety “Dabrava” is grown under natural conditions without irrigation. Every year is fertilization with norm N12P6K6. The analysis of the four-year research shows that the hedgehog head variety “Dabrava” grown on cinnamon forest soil has good adaptability and survival in the conditions of the Sakar region. It’s develops normally, and vegetative development begins in the first ten days of March. In the first year of sowing it develops slowly and the growth rate is the weakest. In the following years the vegetative development has a growth rate, which in ten days reaches 15 cm in the first spring undergrowth and 8.8 cm in the second summer undergrowth. The vegetation period varies in the first spring undergrowth from 60 to 82 days, and in the second summer undergrowth from 51 to 80 days. The height of the grassland in mowing maturity in the first spring undergrowth is from 61.2 to 73.2 cm, and in the second summer undergrowth is from 41.7 - 48.2 cm. The overall vegetative development, growth rate and height of the grassland are directly dependent on climatic factors.
Theoretical determination and analysis of the length of the non-working move and the width of the headland when performing fishtail turn with a rectilinear reverse move, which is not parallel to the boundary of a field with an irregular shape
Authors: Trendafilov Krasimir
Published: February 2021

The way of movement of the machine-tractor units in the field influences the efficiency of the performed operations. A way of movement must be chosen in which the length of the non-working moves and the width of the headland are minimal. When moving in an irregularly shaped field, the length of the non-working moves and the width of the headland depend on the angle between the direction of movement of the unit and the field boundary. In the article dependences for determining the length of the non-working move when performing open and closed fishtail turns with a rectilinear reverse move, which is not parallel to the field boundary, as well as for determining the width of the headland required for their execution are derived. It was found that the non-working move is the shortest and the width of the headland is the smallest when performing a closed fishtail turn and the direction of alternation of the working moves in the field from right to left.
Robust optimization of a deep drawing process
Authors: Paskaleva S M
Published: February 2021

An attempt to define a robust optimization of a deep drawing process is presented in this article, based on window of plastic deformability in the area of main deformations, which is closed between the borders of damage, corresponding to necking, fracture and wrinkling. In the previous investigations of the author, this window has been determined using Finite Element – based computer simulations for technological process of deep drawing of a cylindrical cup. The influence of the stochastic character of the control variables on the quality of the output is examined. An objective function for investigating the robustness of the process, based on the quality of the detail, using numerical simulations, is suggested. The results of the model calibration and optimization run are interpreted. The flexibility of the suggested approach, potential ways to extend it and performance issues are discussed.
A SI engine performance parameters determination for gasoline and methane operation
Authors: Dimitrov R D , Bogdanov Kr Ts , Wrobel R S , Magdziak-Toklowicz M , Andonov N A , Hristov R P , Zlateva P
Published: February 2021

The present paper presents a study whose objective is to determine the performance parameters of an external mixture formation and spark-ignition engine when running on methane fuel. The experiments were carried out using optimum adjusting parameters for engine operation on methane and gasoline fuels. The parameters measured and determined are: brake specific fuel consumption, mean effective pressure, brake power, thermal efficiency, volumetric efficiency and etc. over the entire engine speed range. An analysis of the obtained results is made, comparing the obtained effective parameters at the operation of internal combustion engines with alternative fuel - methane and traditional fuel - gasoline.
An analysis of the potential use of waste materials for biogas plant development
Authors: Zlateva P , Dimitrov R
Published: February 2021

Various industrial waste materials have great potential, especially as a substance for biogas production. The aim of the present study is to analyse the possibility of using the waste materials extracted in Northeastern Bulgaria for biogas plant development. The study indicated that the most common waste materials in Northeastern Bulgaria are in the following ratios Agricultural waste - 44%; Livestock breeding waste - 34%, Waste water - 20% and Seaweed - 2%. Individual samples of the waste materials thus grouped were also examined and biogas was produced from them, after which the density and the lower heating value (LHV) were studied. The analysis of the results showed that the highest LHV are associated with Forage waste - 27.11 MJ/kg, and the lowest one relates to Brown algae - 11.06 MJ/kg, and the density indicates the opposite tendency, with the highest figures related to Brown algae - 1.363 kg/m3, and the lowest values - to Forage waste - 0.994 kg/m3. According to the analysis, the most efficient raw material for biogas production in Northeastern Bulgaria is Forage waste, which is due to its heterogeneous content. In conclusion, Northeastern Bulgaria can be claimed to have various waste materials which are a prerequisite for establishing a biogas production plant.
Problems with the operation of automatic transmissions of AW 55-50 type
Authors: Stefanov S , Hristov R
Published: February 2021

The five-speed automatic transmissions of the AW 55-50 type are widely used in cars. They are used in the transmissions of Opel, Renault, Volvo, Saab, Fiat (Alfa, Lancia), Nissan and GM. Various problems are observed in their operation. Some of the problems are mechanical in nature, requiring major repairs to the transmission. A common defect is a problem in the valve body, which does not require major repairs. Only the valve body is dismantled and repaired without dismantling the entire gearbox. This the report examines characteristics of the linear pressure solenoid (electronic pressure regulator), embedded in automatic transmissions of the type AW 55-50. For this purpose, made special hydraulic fixture with electronic controls, which imitate the work of this pressure regulator under real conditions.
Outdoor vertical farming on textile substrates
Authors: Dirkes L , Massanés J D , Böttjer R , Storck J L , Ehrmann A
Published: February 2021

Vertical farming may solve the problem that in many regions of the world, more area would be necessary to produce food, than it is available. Especially in large cities and other densely crowded areas, vertical farming can provide an efficient and eco-friendly way to feed people. While indoor vertical farming plants are usually highly automatized, outdoor approaches are usually less professionally setup and thus often prone to drying-out, in this way disturbing of even destroying the plants grown in such setups. Here we report on semi-automated irrigation systems, combined with different textile substrates to reduce the risk of fully dried substrates, in order to make inexpensive, successful vertical farming systems available for everybody.
A study on application of the golden and Fibonacci geometry in design of fashion accessories
Authors: Ilieva Julieta , Kazlacheva Zlatina , Dineva Petya , Indrie Liliana , Florea-Burduja Elena
Published: February 2021

The paper presents a study of application of the golden and Fibonacci geometry in design of fashion accessories: bags, scarfs, small accessories, etc. The connection between the application of the golden and Fibonacci geometry in accessories design and sustainable fashion is one of main accents in the study. The application of golden and Fibonacci tilings, floral and animal ornaments, which are created on their base, and geometric forms in golden or Fibonacci proportions are shown. As expressors of beauty, aesthetics, and harmony, the creations on the base of the golden and Fibonacci geometry can be applied in design of fashion accessories directly, as frames, and as parts of new forms. Regardless of the way of the application, the new designs are in strong connections with the sustainable fashion: slow fashion, sustainable trends, zero waste cutting, minimal waste cutting, ecological printing, etc.
E-textile for non-invasive control of the body movement of bedridden patients
Authors: Angelova Radostina A , Sofronova Daniela
Published: February 2021

Decubitus ulcers or bedsores are skin injuries that are a serious medical problem, difficult to treat. They are usually the result of some tissue nutrition disorder, the most common cause being lying down. The main principle for the prevention of this disease is the frequent change of body position of the person or the use of an anti-decubitus mattress. Our study aims the creation of an e-textile for non-invasive control of the body movement of bedridden patients. The use of sensors to monitor body pressure on the mattress would provide information not only on the areas with the most active wearing for each individual but on the current state of the patient: i.e. when it is necessary to change the orientation of the mattress or change the position of the body. It is expected the product to be easy to use and low in price so as to be widely applied and to have a large social impact.
Consumption of Electric Energy in the Production of Cotton Textiles and Garments
Authors: Angelova Radostina A , Velichkova Rositsa , Sofronova Daniela , Ganev Ivaylo , Stankov Peter
Published: February 2021

The production of cotton textiles and garments is of substantial importance for modern society in terms of its economic effect: trade, investment, employment and earnings all over the world. The sector is characterized by substantial demand for electrical energy, alongside with other types of energy resources. The paper discusses the current situation of the production of cotton textiles and garments (import/export), together with the different types of energy, consumed by the textile industry. An in-depth analysis of the energy profile of the manufacturing processes from fibres to garments is performed. The need for a paradigm shift from linear to a circular economy in the field of textiles and clothing production is also discussed.
Industry 4.0 for fashion products – Case studies using 3D technology
Authors: Spahiu T , Manavis A , Kazlacheva Z , Almeida H , Kyratsis P
Published: February 2021

The Fourth Industrial Revolution is based on digitalization where virtual and physical systems of manufacturing are linked and operate together. Fashion products are of a great interest not only as items used to cover and protect the body but even to express individuality, personality and attractiveness. Due to the high interest of consumers for fashion items or products, fashion industry is one of the most important industries globally due to its effect on economic growth. As a result, companies try to invest continually on new technologies by implementing them in various processes of production. The aim of this paper is to present here the implementation of advanced technologies for various fashion products as garments, jewelery and accessories. These products are modelled, evaluated and produced by using 3D modelling software, simulation and additive manufacturing as some of the pillars of Industry 4.0 will be presented. The reduced time, waste and advantages to create, visualize and evaluate products at early stages of product creation are some of the advantages of these technologies, part of Industry 4.0 in the fashion industry.
Feasibility analysis of autonomous hybrid solar-wind system for household consumption: a case study
Authors: Pehlivanova T I , Atanasov A K
Published: February 2021

The constant increase of electricity prices from the power grid, rising fossil fuel prices and environmental motives make people look for opportunities to supply their homes with renewable energy independently from the grid. The easy technical feasibility of the projects and the climatic features of Bulgaria determine the solar and wind energy as the most suitable for the households. The variability of solar and wind energy predetermines their shared use in hybrid systems. Feasibility analysis of autonomous hybrid solar-wind system for household consumption was made in the article. The calculations were made for a residential building located in the village of Okop, Yambol District, Bulgaria. It has been verified if the levelized cost of energy (LCOE) of the domestic solar-wind hybrid system is in parity with the final cost of the grid electricity. Different variants of system configurations and different ways of financing were considered. The results show that for the considered place, the prices of electricity produced by autonomous hybrid systems are higher than the prices of electricity for household customers connected to the power grid. The use of standalone hybrid systems is only justified when there is no power supply from the grid. Lower average prices than those of the power grid are obtained only when building a photovoltaic plant connected to the grid.
Mathematical Simulation of Electrotechnology Characteristics of Mining Complexes
Authors: Petrov V L , Sadridinov A B , Pichuev A V
Published: February 2021

The article presents the results of the research and analysis of the efficiency of power consumption at tunnelling sections in coal mines. The authors established distribution laws for the shift averages of technological and specific consumption of power. Further, they recommended the criteria and principles for the assessment of the power conservation level, efficiency of mine tunneling and works execution arrangement in terms of power sustainable use by shift teams. The recommendations are provided on defining sustainable levels of the shift average power consumption and rationalizing manufacturing standard indices.
Digital transformation challenges of logistics in Bulgaria
Authors: Dragomirov N , Boyanov L
Published: February 2021

This paper investigates the issues of digital transformation in Bulgaria. It presents the major contemporary technologies, used in digitalization and digital transformation and then presents a methodology that evaluates the degree of digital transformation in the area of logistics. Determining the level of basic digitalization of Bulgarian logistics companies is done by developing a methodological framework that covers the main classification of information systems in the area. The indicators covered are in two groups - intraorganizational and interorganisational digitalization. The state of digital transformation is analysed, reviewing small, medium and large enterprises, following a survey within each company. The results show a big potential for the process of digital transformation in Bulgaria in logistics.
Applying text mining methods to extracting information from news articles
Authors: Georgieva-Trifonova Tsvetanka , Dechev Miroslav
Published: February 2021

In the present paper, the text mining methods from the point of view of their application for extracting information from news articles, are discussed. For this purpose, research questions are formulated and opportunities to assist in obtaining their respective answers are presented, as they are illustrated by the application of text mining methods on a created dataset with articles in Bulgarian. The extracted information could be useful for research of the topics covered in the articles, exploration of customer interests, etc.
Attributes selection using machine learning for analysing students’ dropping out of university: a case study
Authors: Pehlivanova T I , Nedeva V I
Published: February 2021

Many students in Bulgarian universities drop out of the university before completing their studies. Identifying students at risk of dropping out allows timely taking measures for their retention. The paper presents the results of a study conducted among students of engineering programs at Trakia University - Stara Zagora. The collected data are subjected to processing, which aims to find the most important attributes that determine the risk of dropping out of university. The processing is done with Weka open source software. Different algorithms for selecting attributes with different search methods are applied. The most appropriate attribute selection algorithm was selected after applying the BayesNet classifier to the results obtained. The indicators TP rate, Precision and F-measure were compared. When applying InfoGainAttributeEval, the highest results are obtained for the accuracy of the classification. At the next stage, it is planned to expand the study among a larger number of students from different programs and create an effective forecasting model.
Students’ Performance Analyses Using Machine Learning Algorithms in WEKA
Authors: Nedeva Veselina , Pehlivanova Tanya
Published: February 2021

Predicting student performance is important for universities. Thus, they can identify students who need support and take measures to improve educational outcomes.

The paper presents analyze of the results of a study conducted at the Trakia University of Stara Zagora. The study aims to identify the most significant features that affect student performance and to select the most efficient machine-learning algorithm to predict their performance.

The efficiency of four classification algorithms was compared-BayesNet (BN), Multilayer Perceptron (MLP), Sequential minimal optimization (SMO) and Decision tree (J48). For comparison, the indicators TP Rate, Precision, F-Measure, Accuracy and error measures-MAE, RMSE, RAE, and RRSE were used. The processing is done with Weka open-source software. The obtained results show that the MLP algorithm is the best for the used data. The obtained accuracy is sufficient to create an effective forecast model. 12 attributes have been identified that have the greatest impact on student performance.
E-assessment-beyond the traditional assessment in digital environment
Authors: Kiryakova Gabriela
Published: February 2021

An assessment is an integral part of the learning process, which determines whether and to what extent the learning objectives have been achieved. It indicates whether the used tools, technologies and pedagogical approaches have produced positive results. Today technologies are implemented in all stages and activities in the learning process. They allow teachers to diverse, enrich and develop traditional assessment methods. E-assessment guarantees rapid, instant, automated results and feedback and the implementation of new approaches for assessing learners’ knowledge. Learning Management Systems offer a variety of tools for e-assessment and provide the opportunities to integrate assessment exercises into other learning activities. The aim of the current work is to present some of the innovative assessment tools in Learning Management Systems illustrated by LMS Moodle. They allow the implementation of new assessment approaches that differ from traditional ones. They prove the thesis that e-assessment is not equivalent to traditional assessment carried out in a digital environment and provides new attractive opportunities and techniques for evaluating various aspects and levels of knowledge, skills and competencies.
Hybrid model for quality evaluation in secondary education
Authors: Docheva M , Totkov G , Gaftandzhieva S , Doneva R
Published: February 2021

The paper introduces a hybrid model for quality evaluation of the educational process in high school, based on a set of qualitative and quantitative indicators. The model overcomes the subjectivity of external evaluation by using a relatively small number, clear and objectively measurable criteria for different types of indicators, divided into 12 groups. All 132 indicators (75 qualitative and 57 quantitative) are measures of the educational process from different points of view -to measure compliance of essential quality criteria with European and national best practices, to objectively compare specific numerical indicators, etc. Quality indicators are evaluating by using two types of measuring scales. The first type is suitable for such indicators which are used mainly to classify the assessed objects according to a specific characteristic. The second type of measuring scales are suitable for indicators, the values of which are used to compare the qualities of objects. The proposed hybrid model for quality evaluation of high schools uses 4 measurement scales, based on relative measurements of 57 quantitative indicators.
Fuzzy U-Net Neural Network Architecture Optimization for Image Segmentation
Authors: Kirichev M M , Slavov T S , Momcheva G D
Published: February 2021

In this article, the optimization of the modified U-Net neural network model extended with fuzzy layers has been studied with the usage of Grid search and Keras tuner. The article is a continuation of previous work where the model is suggested and explored. From one point of view, the research is focused on the optimization of Fuzzy Layers embedded in the U-Net model in order to find the better neural network architecture for nuclei segmentation in the research work in BioMed Varna R&D ecosystem for the segmentation of cellular nuclei. At the same time from a global perspective, this experiment is a part of the bigger one for the searching of new neural network architecture design techniques.
Generation of phase trajectories of experimental data
Authors: Yankov K B
Published: February 2021

The phase plane method (PPM) is a graph-analytical approach for studying the stability and long-time behavior of systems described by differential equations. In order to apply the PPM to experimental data, it is necessary to identify these data with a first-or second-order differential equation. This work presents a numerical-analytical algorithm for obtaining phase trajectories from experimental data avoiding identification with a differential equation. For this purpose, the data are interpolated with a cubic spline. The first derivative was obtained analytically from the spline. The abscissa coordinates are the values of the spline at a given point, and the ordinate is the analytical representation of the first derivative. As an example, the phase trajectory of the dose-dependent curve of the drug tubazid is constructed by two methods-with identification of the differential equation describing the process and with the algorithm proposed in the article. The approach is implemented with Korelia software.
Risk analysis in terms of implementation of large scale cogeneration power plant
Authors: Terziev A K , Beloev H I , Iliev I K
Published: February 2021

The introduction of large-scale technology carries a number of risks. This paper presents the risks associated with the introduction of a system for combined production of electricity and thermal energy (CHP) through direct combustion of biomass. It is envisaged that the residual amount of heat energy will be converted into electricity through the use of an ORC module. All possible risks have been identified based on the technology specifics, and the possible consequences of the risk have been indicated. A risk matrix has been prepared for both site and technology specifics in order to identify the type of risk. Based on the outputs, a proposal for reducing the risk has been made.
Technology of butter fortified with phytosterols
Authors: Ivanova M G , Dobrev G T
Published: February 2021

The aim of the resent study was to determine the appropriate moment to enrich the butter with phytosterols. The butter was enriched in phytosterols at three different stages of the technological process – before cream pasteurisation (batch B), before cream ripening (batch C) and before working the butter into a continuous fat phase (batch D). A control sample with no added phytosterols was prepared (batch A). The titratable acidity of cream before and after biological ripening and of the resulting butter was determined. No significant differences between samples were found (p>0.05). The fat, moisture and phytosterol content of butters, produced from different batches, were evaluated. Any significant differences between samples were found (p>0.05). The number of lactic acid microorganisms in the final product was similar in all analysed samples (p>0.05). The butters enriched with phytosterols were characterized by high sensory scores comparable with those of the control sample (p>0.05). This study suggested that the addition of phytosterols in butter could be performed at different stages of the technological process with no reflect on the phytosterol content in the final product. From a safety point of view, it is appropriate to add the phytosterols before pasteurisation process. The obtained butter is considered as functional product with potential health effects.
Volatile compounds in flowers, samaras, leaves and stem bark of Ailanthus altissima (Mill.) Swingle, growing in Bulgaria
Authors: Andonova Ts G , Dimitrova-Dyulgerova I Zh , Slavov Zh , Dincheva I N , Stoyanova A S
Published: February 2021

The aim of the present study was to determine the composition of essential oils (EOs) of different plant parts of A. altissima, growing in Bulgaria. Four samples (flowers, immature samaras, leaves, stem bark) of A. altissima were collected in the period June-July of the 2019 growing season, from Plovdiv, Bulgaria. The EOs were obtained by hydrodistillation with a Clevinger-type apparatus. Gas Chromatography/Mass Spectrometry analysis was applied to determine the volatile compounds. The yield (in fresh material) was 0.5 ml/kg (samaras), 0.27 ml/kg (flowers), 0.23 ml/kg (leaves), and 0.18 ml/kg (bark). There were identified 75 volatiles from the different plant parts. Oxygenated hydrocarbons (mainly fatty acids, their esters) were the best-represented group in samaras, leaves, bark (65.87%; 47.53%; 49.41% respectively). Oleic acid was the major constituent in the three EOs (samaras -34.26%; stem bark -30.21%; leaves -22.94%). In the flower EO, the dominant group was sesquiterpene hydrocarbons (46.48%) with main compounds β-caryophyllene (16.98%) and germacrene D (16.24%). The volatile components in Ailanthus altissima, growing in Bulgaria, have been determined for the first time. Differences in the composition of EOs were found.
Investigation and characterization of O/W emulsions on stability with different methods
Authors: Gandova V D , Tasheva STz , Petrova I G , Dobreva K Z
Published: February 2021

The properties and efficiency of O/W emulsions were investigated. Influence by oil phase in the emulsification processes was determined. After centrifugation measurements in emulsions with high percent oil four phases were observed. pH values in all emulsions was measured and found from 5.8 to 6.3 in connection with application of foods. During the storage period of fourteen days the spectroscopic measurements were perform in continuous phase and middle radius of particle sizes were calculated.
Technological aspects of obtaining ethanol extracts from Physalis alkekengi L. leaves
Authors: Ivanova T A , Popova V T , Tasheva S T , Mazova N N , Stoyanova A S
Published: February 2021

The aim of the study was the provision of a technological background for obtaining ethanol extracts with prospective cosmetic application from the leaves of P. alkekengi L. Extraction was carried out in laboratory conditions, as a batch static mode process, with four solvents, 95%, 70%, 50%, and 30% ethanol, respectively. The influence of the main technological factors, temperature (20°C, 40°C, and 60°C) and duration (1 h, 3 h, 5 h and 7 h), upon the content of tannins in the extracts was studied by mathematical modelling of the experiment. The equations of extraction, based on the concentration of extracted tannins were derived. The optimal conditions for the extraction procedure of P. alkekengi leaves were determined (70% ethanol, 5 h, 60°C). The results from the study, i.e. the dynamics of tannin extraction, the equations of extraction and the technological factors’ combination, could be applied in the obtaining of P. alkekengi leaf extraction products intended for use in different personal care products; of course, additional investigations on the subject are necessary, especially in terms of extracts’ individual composition and biological activities.
The leaves and stems of Cape gooseberry (Physalis peruviana L.) as an alternative source of bioactive substances
Authors: Popova V T , Ivanova T A , Stoyanova M A , Mazova N N , Panayotov N D , Stoyanova A S
Published: February 2021

The objective of this work was the investigation of the chemical composition of the leaves and stems of two Cape gooseberry (Physalis peruviana L.) genotypes from Bulgaria (CG-SB and CG-NB), with the view of establishing the presence of certain bioactive substances and the prospects for their use as livestock feed or cosmetic ingredients. The leaves and stems of CG-SB genotype contained 18.63% and 40.26% cellulose, respectively, and 24.83% and 13.73% protein; the respective contents in the leaves and stems of CG-NB genotype were 27.63% and 47.63% cellulose, and 9.36% and 8.07% protein. The dominant amino acids in CG-SB leaves were aspartic acid (32.04 mg.g-1) and lysine (30.54 mg.g-1), and in the stems – proline (46.90 mg.g-1) and phenylalanine (15.42 mg.g-1). The amino acid composition of the leaves of CG-NB genotype was dominated by histidine (24.88 mg.g-1) and proline (21.25 mg.g-1), and that of the stems – by proline (13.38 mg.g-1). The main macro and micro minerals in the leaves and stems of both genotypes were K, Mg and Fe, respectively, but numerical differences were observed on a genotype and plant part basis. The leaves were processed by extraction with n-hexane and the content of volatiles was determined (by GC-MS). A total of 32 components was identified in each of the genotypes. The major volatile in both genotypes was n-pentacosanol, 17.07% in CG-SB and 12.39% in CG-NB; the dominant group of chemicals was that of oxygenated aliphatics, followed by diterpenes. The results from the study provide arguments that the leaves and stems of Cape gooseberry, currently discarded byproducts, could be regarded as alternative sources of bioactive substances.
Effect of hop extracts on rheological properties of wheat dough
Authors: Sokolova N
Published: February 2021

The choice of technological equipment and the mode selection in bakery industry is determined by the rheological properties of the processed or transported food masses, pre-ferments, and products. In this aspect, the effect of new ingredients in bakery production such as two types of hop extracts (the hop-water and hop-milk whey systems) and their percentage in the formula on the rheological properties of wheat dough during kneading and fermentation has been investigated. The effect of extracts and their percentage in dough formula on time development and strength of the dough has been studied. It was found, using the Brabender Farinograph, that hop extracts lead to decreasing of the elasticity and degree of softening of wheat dough with hop-water extract by 9—27% compared to the control, and hop-milk whey-by 33—41%. Brabender Extensograph carried out the assessment of changes in physical properties of the dough with hop extracts during fermentation after 45, 90 and 135 min. It was found that hop extracts increase the strength of the dough and resistance to extension, which also indicates strengthening effect of hop extracts on wheat gluten. The changes in the quality characteristics of wheat bread with different dosage of hop extracts have been investigated. It was found that the addition of the extract based on water increases the ability to hold the shape of baked bread, on average, by 2—17% whereas extract based on whey increase this index by 8—25%.
Mid-season peach varieties – physicochemical and sensory profile
Authors: Mihaylova Sp D , Popova A T , Dessev Tz T , Petkova N T
Published: February 2021

Prunus varieties are a major contributor to bioactive compounds in the daily diet in the spring and summer. There is a need to disseminate knowledge about the benefits of consuming fruits and their products to the public and to expand research into the potential for harnessing their health potential. The study aims at evaluating target physicochemical and composition attributes of two mid-season ripening dessert peach varieties: “July Lady” (freestone) and “Laskava” (freestone). Fruit weight, shape and size, as well as colour and firmness were evaluated. Image analysis was used to describe properties such as length, width, thickness, etc. Dry matter (%), ash content (%), total soluble solids, pH, titratable acidity, total sugar content, and protein content were employed to characterize the studied varieties. Total soluble solids varied from 12.52 to 13.52 and dry content-from 14.98 to 16.16%. A descriptive sensory method characterised the studied varieties, and the panellists detected differences in each of the categories (aroma, taste, texture and appearance). These results highlight new data about peach varieties and help to better feature their unique characteristics.
Biologically active compounds from Tussilago farfara L
Authors: Stoyanova M A , Perifanova-Nemska M N
Published: February 2021

The modern interest in the chemical component of the coltsfoot is due to the fact that many of the ingredients in the tea have physiological activity and can be used in the treatment and prevention of many diseases. The results from this study showed, that the main phenolic acids was caffeic acid (1867.34±3.12 μg/g), ferulic acid was in approximately lower concentration, triple lower than caffeic acid (545.23±4.36 μg/g), while chlorogenic acid was not detected. Ascorbic, malic and citric acids were determined by HPLC analysis as the main organic compounds in the leaves of coltsfoot. The most abundant organic acids were ascorbic acid (67.43±0.95 mg/g) and malic acid (45.25±1.15 mg/g). The 17 amino acids were determined in our study. The highest quantities of essential amino acids were phenylalanine (6.23 g/100 g protein) and valine (5.56 g/100 g protein). Other essential amino acid such as threonine, leucine, isoleucine and lysine were found at 4.90 g/100 g protein, 4.64 g/100 g protein, 3.76 g/100 g protein, and 2.45 g/100 g protein respectively.
Influence of sucrose and barley flour on some physical, texture and sensory characteristics of cookies
Authors: Nakov Gjore , Dimov Ivan , Taneva Ira , Stamatovska Viktorija
Published: February 2021

The aim of the present paper is to establish the influence of sucrose on the basic properties of the cookies – losses during baking, thickness, volume, specific volume, colour, as well as on their texture and sensory characteristics.

A total of six kinds of cookies were prepared from wheat four, barley flour and mixture of them in ratio 50:50, in two groups according to the sweetener used – with and without sucrose. The results obtained indicated that sucrose and the barley flour exert certain effect on the basic physical properties of the cookies, as well as on their texture and sensory characteristics.

When sucrose is used for preparation of cookies, beside that it imparts sweet taste, the baking losses decreases (13.64 %), thicker cookies are produced (15.95 mm), diameter (68.90 mm), expansion factor (44.43), volume (40 cm3) and specific volume (1.65 cm3/g) compared to the cookies prepared without sucrose. The sucrose containing cookies are harder, darker and have more intense red and yellow colour. It was found from the sensory analysis carried out that these cookies are preferred by the consumers.

The addition of barley flour to the cookies composition results in higher loss during the baking but the cookies obtained have bigger diameter compared to these which do not contain barley flour. The cookies prepared from mixture of wheat and barley flour in ratio had the best sensory properties.
Synthesis, characterization, and activity of 6-(10H-phenothiazine-10-yl)-1H,3H-benzo[de]-isochromen-1,3-dione derivative of 4-aminophenylacetic acid
Authors: Haralanova T , Marinov M , Kostova I , Nikolova I , Damyanova S , Stoyanov N
Published: February 2021

The objective of the present paper was to study the synthesis of a new compound 6-(10H-phenothiazme-10-yl)-1H,3H-benzo[de]-isochromen-1,3-dione derivative of 4-aminophenylacetic acid (PTZD). Its physicochemical characteristics and spectral data were presented. PTZD was found to have good inhibitory activity. The phenothiazine derivative showed good fungicidal activity against the studied yeast (S. cerevisiae and C. albicans) and mold species (A. brasiliensis and F. moniliforme), weak bactericidal activity against the Gram-positive bacteria S. aureus and B. subtilis and did not affect the growth of Gram-negative bacteria E. coli, P. aeruginosa and S. abony.
Synthesis, complexation properties, antimicrobial and anticoagulant activity of 2-{3-[4-(dimethylamino)phenyl]-1-hydroxyprop-2-en-1-ylidene}-4-nitro-1H-indene-1,3(2H)-dione
Authors: Nikolova I , Kostova I , Staneva M , Marinov M
Published: February 2021

This article presents the synthesis of a new 4-nitro-cinnamoyl derivative of 2-acyl-1,3-indandione. The resulting compound was subjected to interaction with ErCl3x6H2O, which was obtained from Er2O3 and HCl. The synthesized compounds were proven by IR and NMR spectroscopy. The spectral data clearly proves the formation of a chelate complex. A probable structural formula of the coordination compound is also proposed. The obtained compounds were used for analysis of their antimicrobial and anticoagulant activity.