Effect of different light intensities on prolactin and cortisol plasma concentration in farming African catfish (Clarias gariepinus) in RAS with low-water exchange

In the Bulgarian aquaculture sector, focusing research efforts on the technical specifications of the cultivation of African catfish (Clarias gariepinus) is important due to the need for more information. We aimed to assess the impact of light intensities on prolactin and cortisol levels as stress markers in African catfish. Fish were acclimated over an appropriate period to the short photoperiod (16D and 8L) and then distributed randomly to three groups, each separated by sex. Fish exposed to different light intensities (63, 51, and 40 lux, respectively) were followed for 45 days by lux meter. Blood samples were collected from the caudal vein using a 2 ml K2EDTA-coated syringe. A laser fluorescence reader assayed plasma prolactin and cortisol. The pituitary was removed from anesthetized fish and fixed for histological examinations. The results of our study suggest that increasing light intensity increases prolactin and cortisol levels in African catfish

CHEMICAL ANALYSIS OF WATER USED FOR FISH FARMING IN TUNDZHA RIVER, BULGARIA

The aim of the study was to assess some chemical parameters in water from Tundzha River used for common carp (Cyprinus carpio L.) farming. Water samples were taken according to protocol in September 2014 from the fish farm located near the town Nikolaevo. Results showed compliance with regulations for most of the studied parameters. A slight increase of ammonia (NH3) was found in the control sample. In both locations elevation of nitrates (NO3) and phosphates (PO4) was registered, suggesting contamination of the water from agricultural use of organophosphate insecticides and nitrogen fertilizers. In conclusion, effective measures should be taken to protect water resources in Tundzha River used in fish farming from agricultural pollution

Role of Foundations, Funding Research and Innovation in the Bulgarian Society

This report analyses the role of foundations, funding and/or carrying out research and innovation programs in Bulgaria supporting the development of science and scientific institutions. In particular, we examine the types of foundations; origin of their funds and main sources of funding; their investments in research and innovation; supported key research areas; their role in the sphere of research and innovation. Empirical data in the report were collected through a large-scale survey of EU foundations and NGOs, funding and/or engaged in research and innovation, where ISSK – BAS was the Bulgarian partner. The survey was funded by the European Commission and was carried out in the period 2013-2014 in all EU Member States plus Switzerland and Norway. Coordinator of the research was the Department of Social Sciences at the Free University (VU) in Amsterdam

Challenges for Health Monitoring of Electromechanical Flight Control Actuation Systems

Flight control systems of civil aircraft have undergone huge developments in the last decades. The current more/all electric aircraft concepts lead to the replacement of the hydraulic actuators in the primary flight control systems by electromechanical systems. Integrating electromechanical systems in safety critical applications implies three main challenges: (a) the detection of all fault cases which could lead to a safety critical state, (b) finding measurement parameters capable to detect faults, and (c) the development of algorithms to detect faults under all flight conditions. Putting the scope on the health monitoring of the mechanical components of a direct drive actuator, a new technology based on piezoresistive thin film sensors (TFS) is presented and its potential shown by using defective ball bearings as an example

Influence of Systematic Mineral Fertilization on the Yield and Quality of Malting Barley Variety quot%253BAhatquot%253B

The study was carried out during the period of 2019-2021 in the experimental field of the IASS quot%253BObraztsov chiflikquot%253B - Ruse in a long-term stationary fertilizer trial with a 4-pole crop rotation, including interchange of corn, barley, beans and wheat, according to the scheme of Georges Ville in three replications located according Rümker. Fertilization options are the individual and combined application of the three macroelements ndash%253B nitrogen, phosphorus, potassium and the non-fertilized control is used for comparison. The yields of the wintering malting barley variety quot%253BAhatquot%253B grown in the conditions of permanent fertilizer experiment are affected by the weather conditions, and during the research period 2020 appears to be the most favorable for the development of the crop, due to the sufficient amount of evenly distributed precipitation and its combination with optimal average monthly temperatures during the growing season. In all years of testing, the variants with individual and combined application of nitrogen showed proven higher yields compared to the control. The long-term accumulation of phosphorus and potassium in the variants with their individual and combined applications has a depressing effect on the plants, and hence a negative impact on the yield. The quantitative and qualitative indicators of the grain are changed under the influence of fertilization, analogously to yields. The parameters mass per 1000 grains, germination and crude protein content were higher in the variants with nitrogen fertilization and decreased or close to the control in the other variants. Differences in hectoliter weight and grain uniformity are not statistically proven