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The aim of the present study is the production of stocking material of European catfish (Silurus glanis L.) using common carp larvae (Cyprinus carpio L.) as natural food source. The experiment was carried out in two earthen ponds (№18 and №19). The stocking material was produced through semi-artificial reproduction of European catfish and natural reproduction of common carp in two stages. The main aquaculture production indicators of the stocking material of European catfish and common carp were calculated: growth (WG, g), survival (%), total yield (kg) and average yield (kg/1000 m² ). The obtained results show that the growth of European catfish in pond №19 is 69.67 g, while in pond №18 it is 58.91 g. Also, the survival rate in pond №19 is 2.8 times higher than in pond №18. After analyzing the obtained results, it can be concluded that the production indicators of the European catfish stocking material are higher in experimental pond №19. [ABSTRACT FROM AUTHOR]

Background: Specifically designed peptide mimetics offer higher selectivity regarding their toxicity to mammalian cells. In addition to the α-helix conformation, the specific activity is related to the peptide's ability to penetrate the cell membrane. The alterations in lipid membrane properties were addressed in the presence of the peptide KLAKLAK-NH2 and analogs containing β-alanine, strengthening the antibacterial activity and/or naphtalimide with proven anticancer properties. Methods: The molecular interactions of the peptide mimetics with POPC bilayers were studied using FTIR-ATR spectroscopy. The thermal shape fluctuation analysis of quasispherical unilamellar vesicles was applied to probe the membrane bending elasticity. The impedance characteristics of bilayer lipid membranes were measured using fast Fourier-transform electrochemical impedance spectroscopy. Results: A lateral peptide association with the membrane is reported for β-alanine-containing peptides. The most pronounced membrane softening is found for the NphtG-KLβAKLβAK-NH2 analog containing both active groups that corroborate with the indications for 1,8-naphthalimide penetration in the lipid hydrophobic area obtained from the FTIR-ATR spectra analysis. The β-alanine substitution induces strong membrane-rigidifying properties even at very low concentrations of both β-alanine-containing peptides. Conclusions: The reported results are expected to advance the progress in tailoring the pharmacokinetic properties of antimicrobial peptides with strengthened stability towards enzymatic degradation. The investigation of the nonspecific interactions of peptides with model lipid membranes is featured as a useful tool to assess the antitumor and antimicrobial potential of new peptide mimetics. [ABSTRACT FROM AUTHOR]

The purpose of the present study is to examine the efficacy of lemongrass oil (Cymbopogon schoenanthus) by establishing the time needed for induction and recovery from anesthesia of common carp (Cyprinus carpio, Linnaeus 1758) stocking material. The fish have an average body weight (BW, g) of 14.15±4.68 g and an average total length (TL, cm) of 10.92±4.17 cm. Ten treatments are conducted with ten experimental concentrations: 0.02 ml/l-1, 0.04 ml/l-1, 0.06 ml/l-1, 0.08 ml/l-1, 0.10 ml/l-1, 0.12 ml/l-1, 0.14 ml/l-1, 0.16 ml/l-1 . 0.18 ml/l-1 and 0.20 ml/l-1 . For each concentration 10 fish (five treatments with two fish) are used or a total of 100 fish for the whole experiment. At concentration of 0.20 ml.l-1 the induction of anesthesia is the fastest (2.14±0.20 min), thus the recovery time at this concentration is the longest (7.06±0.59 min) (P≤0.05). From all tested concentrations the recovery time is the shortest at concentration 0.04 ml.l-1 – 2.61±0.43 min (P≤0.001). The lowest concentration (0.02 ml.l-1 ) has no anesthetic effect on carp stocking material. Based on the results obtained from the current experiment it can be concluded that lemongrass essential oil is effective as anesthetic agent for common carp stocking material, which makes it applicable in the fish farming practice. [ABSTRACT FROM AUTHOR]

Multiforce nickel–titanium (NiTi) orthodontic archwires release progressively increasing forces in a front-to-back direction along their length. The properties of NiTi orthodontic archwires depend on the correlation and characteristics of their microstructural phases (austenite, martensite and the intermediate R-phase). From a clinical and manufacturing point of view, the determination of the austenite finish (Af) temperature is of the greatest importance, as in the austenitic phase, the alloy is most stable and exhibits the final workable form. The main purpose of using multiforce orthodontic archwires is to decrease the intensity of the applied forces to the teeth with a small root surface area, such as the lower central incisors, and also provide forces high enough to move the molars. With the optimally dosed forces of multiforce orthodontic archwires in the frontal, premolar and molar segments, the feeling of pain can be reduced. This will contribute to the greater cooperation of the patient, which is of utmost importance to achieve optimal results. The aim of this research was to determine the Af temperature at each segment of as-received and retrieved Bio-Active® and TriTanium® archwires with dimensions of 0.016 × 0.022 inches, investigated by the differential scanning calorimetry (DSC) method. A classical Kruskal–Wallis one-way ANOVA test and multi-variance comparison based on the ANOVA test statistic using the Bonferroni corrected Mann–Whitney test for multiple comparisons were used. The incisor, premolar and molar segments have different Af temperatures, and they decrease from the anterior to posterior so that the posterior segment has the lowest Af. Bio-Active® and TriTanium® with dimensions of 0.016 × 0.022 inches can be used as first leveling archwires by additional cooling and are not recommended for use on patients with mouth breathing. [ABSTRACT FROM AUTHOR]

Aquaculture production in Bulgaria has increased over the last decade, reaching 16 442 tonnes in 2019. Fish production has doubled in comparison with 2007, while that of mussels has increased tenfold. The Bulgarian contribution to EU aquaculture production has been increasing significantly in both volume and value over the years, making up 1.15% of the volume and 1.0% of the value of EU production in 2019. Freshwater aquaculture accounts for 78% of total production. Common carp dominates with about 29.4% (4836 t), followed by rainbow trout with 29.2% (4820 t) in 2019. The cultivation of sturgeon species and caviar production are among the most dynamically developing aquaculture segments. Mariculture in the Black Sea has increased in recent years, with the production of Mediterranean mussel reaching 2932 tonnes in 2019. An average of 405 farms operated during the period 2010-2019. Four regions (Plovdiv, Stara Zagora, Burgas and Montana) account for 50% of the total fish production. Pond aquaculture is the dominant technology used in Bulgaria, and it serves as the basis for numerous other activities, including management of fish stocks in various water bodies mainly for recreational fishing. Approximately 35 net-cage farms currently operate in bigger dams. Recirculating fish farms output made up only 0.15% of the total amount of aquaculture for the period 2010-2019. The aquaculture sector exhibited difficulties in recovering from the financial crisis of 2007-2008, manifested by a slow growth for the period 2010-2014. From 2015 to 2019 there has been a significant growth, manifested in a sharp increase of total revenue and profitability, especially among the larger enterprises in the sector, as well as an increase in the number of employees, and the labour productivity. As a result, in 2019 the registered total revenue per enterprise and total revenue per employee were more than double the respective figures for 2010. The profits of larger enterprises increased more than three times on average, but smaller entities, micro-enterprises with less than 5 employees, operated at the border line between profit and loss. The COVID-19 crisis could have lasting consequences. Despite EUR 1.2 million direct payments in the sector in 2020, there has been a significant drop in the export of aquaculture products. Consumption of fish and other aquaculture products remains low compared to those in the other EU countries. [ABSTRACT FROM AUTHOR]

Multiforce orthodontic archwires are thermodynamic wires made of nickel-titanium alloy (Ni-Ti). They release biologically tolerable forces along their length, progressively increasing from front to back. The frontal archwires' segments distribute the weakest force: the premolar, the greater, and the molar, the greatest. The aim of the present study was to determine the influence of clinical use on the mechanical properties of two types of multi-force orthodontic archwires (TriTanium®, American orthodontics; Bio-Active®, GC) with dimensions of 0.016 × 0.022 inches for periods of up to 8 weeks and over 8 weeks of in-vivo use. A three-point bending test was used, and the data gained is statistically analyzed through a multi-variance comparison Mann-Whitney test. We found that after uses of up to 8 weeks and over 8 weeks, the shape memory effect and superelasticity are preserved, as well as the tendency for differential force release along the length of the archwires is kept. [ABSTRACT FROM AUTHOR]

Purpose: Most of the orthodontic archwires used in the clinical practice nowadays contain nickel (Ni), however many patients and especially kids are allergic to Ni. One possible Ni-free alternative is the Titanium-Niobium (Ti-Nb) archwire. Unfortunately, there is not enough information about its mechanical properties in the literature, especially after clinical usage. Therefore, the aim of this work was to investigate and compare the mechanical properties, chemical composition, structure and morphology of as received and used in clinical practice Ti-Nb orthodontic archwires. Materials and Methods: We investigated and compared as received and clinically retrieved after 4 and 6 weeks respectively Ti-Nb archwires with dimensions 0.43 x 0.64 mm (0.017 in. x 0.025 in.). The following methods were used: instrumented indentation testing (nanoindentation), X-ray diffraction, Scanning electron microscopy, Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Results: The nanoindentation investigations of as received and used Ti-Nb archwires revealed a decreasing in their indentation hardness with increased periods of use in the patient's mouth. Moreover, an increasing of the concentration of Ti in the content of the TiNb alloy was associated with an increased period of use in the oral cavity. The SEM analysis showed changes in surface morphology with increasing the period of use of the archwires. Conclusions: The results showed that there are slight changes in the mechanical and physicochemical properties of the investigated wires after their use in the patient's mouth. That is why we do not recommend them for recycling. [ABSTRACT FROM AUTHOR]

The present study analyzed the interactions between the environmental parameters, microbiological water quality indicators, and phytoplankton in Kardzhali reservoir, which is one of the largest and economically significant water bodies in Bulgaria, with highly developed cageaquaculture. Data sets of eighteen parameters from 5 monitoring sites during 2016-2018 were used for analysis. We have applied multivariate methods, aiming to identify the key parameters affecting the communities, including the impact of the net-cage farms. The ANOSIM (analysis of similarities), showed significant differences in the values of physicochemical factors between the control site and the area for aquaculture, with higher nitrate, total nitrogen, and COD (chemical oxygen demand) content near the net-cages. The results were confirmed by the high R-value (R=0.87; p<0.01). The conducted PCA (principal component analysis) showed that only three principal components (PCs) are need to group the physicochemical parameters, explaining 90.5% of the total data variation. PC1 was formed by nitrogen forms and COD, PC2 represents the physical source of the variability (pH and dissolved oxygen) and PC3 was loaded with total phosphorus (0.537) and ammonium nitrogen (0.764) concertation. The parameters with the highest impact on the abundance of heterotrophic bacteria (TVC) include temperature, TN, and COD, while the phytoplankton community was negatively correlated with Secchi depth and COD. The redundancy analysis confirmed that the location of the sampling station significantly affects the studied variables and that net-cage aquaculture is a major anthropogenic factor in Kardzhali reservoir. [ABSTRACT FROM AUTHOR]

The aim of the present study was to update the current status of the phytoplankton composition in Bulgarian reservoir with high social, environmental and economic importance such as the Batak reservoir and to analyze its relationship with the total bacterial count (TVC) and the environmental factors. A total of 106 phytoplankton taxa were identified for the study period. Class Bacillariophyceae was presented by the highest number of species (34) followed by divisions Chlorophyta (26) and Cyanoprokaryota (17). The maximum of species diversity was established in the samples from September at the station situated near the dam wall (S1) with the lowest number being detected in July at the same station. The phytoplankton abundance (PhN) and biomass (PhB) has reached their maximum in September with highest values in the epilimnion samples with a steep decrease in depth of the reservoir. Seasonally and spatially waters were dominated by the diatoms Tabellaria fenestrata var. asterionelloides Grunow, Fragilaria crotonensis Kitton, green algae Pandorina morum (O.F.Müller) Bory, and Desmodesmus communis (E. Hegewald) E. Hegewald. Aphanizomenon fl osaquae Ralfs ex Bornet & Flahault is presented with relatively high numbers. A Woronichinia naegeliana (Unger) Elenkin bloom was established in November at the tail of the reservoir. Significant positive correlations were established between phytoplankton abundance and the nitrogen forms, total phosphorus, with negative correlations between PhN and TVC. According to cluster analysis, the surveyed stations are grouped into two separate clusters each with similar spatial and seasonal characteristics. The stations at the dam wall and at the tail of the reservoir are characterized by the highest hierarchical distance. [ABSTRACT FROM AUTHOR]

Tellurium based materials possess a low temperature phase change transition. Sometimes they cannot be obtained in an amorphous state under normal conditions. Thus they can be used as an active element in phase change memory devices. Our study is dedicated to the synthesis of tellurium based materials using the systems (GeTe3)100-xInx, x = 5 mol %, 10 mol %, 15 mol % and 20 mol % and (GeTe4)100-xInx, x = 5 mol %, 10 mol %, 15 mol % and 20 mol %, the deposition of thin films on their ground and the investigation of their morphology, topology and structure aiming to obtain new knowledge for evaluation of the possibility for application of these materials in phase change memory devices. [ABSTRACT FROM AUTHOR]

The aim of the present study is to analyze the chemical composition of the meat and fatty acid profile of carp lipids (Cyprinus carpio L.) before and after heat treatment (baking and frying). The water content (weight method), proteins (Kjeldahl procedure), fat (arbitrage method), ash (weight method) and fatty acid composition (GC) are determined for carp from aquaculture - pond - and cage reared and for free-living carp from Zhrebchevo dam lake. It has been established that the level of water in the baked and fried carp decreases as a result of the heat treatment. Increases in protein, fat and ash content in heat treated meat samples compared to fresh carp meat are reported. The fatty acid profile of baked and fried carp showed a slight decrease in the level of saturated and monounsaturated fatty acids. An increase in the percentage of polyunsaturated fatty acids as a result of heat treatment is reported. The omega-3 fatty acid group is characterized by minor changes and relatively stable levels in baked and fried carp. The values of the biologically important ω-6: ω-3 ratio in the fresh carp meat from all tested rearing groups ranged from 1.69 to 2.63%. For baked and fried meat samples, higher values are reported, respectively 4.83-6.28% for baked and 4.28-7.60% for fried ones. As a result of the thermal treatment, the values increase in both processing methods and exceed the recommended 5:1 ratio. The fried carp meat are characterized by higher ω-6:ω-3 ratios compared to baked, indicating that carp lipids in baked carp are more balanced and biologically more complete and have a lower risk factor for human health. [ABSTRACT FROM AUTHOR]