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In the current investigation, the removal efficiency regarding a cationic dye, methylene blue (MB), from three graphene-based materials was investigated. The materials' characterization process involved instrumental methods such as XRD, XPS, SEM, TEM, FTIR, and nitrogen adsorption at 77 K. The survey examined how various process factors influenced the ability of the studied materials to adsorb cationic dyes. These parameters encompassed contact time, initial dye concentrations, solution pH, and temperature. The adsorption procedure was effectively explained through the application of pseudo-second-order and Langmuir models. The maximum adsorption capacity for the best adsorbent at 293 K was found to be 49.4 mg g -1 . In addition, the study also determined the entropy, enthalpy, and Gibbs free energy values associated with the removal of MB and showed that the adsorption of MB is endothermic, feasible, and spontaneous. The results also revealed that the studied materials are suitable adsorbents for the removal of cationic dyes.

This study attempts to provide a deeper insight into the current genetic status of 12 Bulgarian autochthonous sheep breeds using microsatellite (SSR) markers. A total of 600 individuals from 50 flocks were analyzed using a panel of 13 SSR markers. In total, 228 alleles were found in the studied microsatellite loci. The mean number of alleles, the effective number of alleles, and the polymorphic information content (PIC) values per locus were 17.54, 5.250, and 0.799, respectively. The expected heterozygosity (He) for all breeds ranged from 0.70 to 0.82. The within-population heterozygote deficit (Fis) varied from -0.03 to 0.1, reflecting significant levels for 10 of the 12 breeds. The average genetic differentiation (Fst) was 0.046, revealing a low discrimination between the breeds. The genetic distance, principal coordinate analysis, and the structure analysis showed that two of the studied breeds-Local Stara Zagora/SZ/ and Local Karnobat/MK/-were the most distinct sheep populations. The Bayesian clustering approach suggested poor breed differentiation for the remaining 10 sheep breeds. The results suggest that proper management strategies and specific breeding policies need to be implemented in Bulgaria to avoid the intermixing of breeds and to reduce the erosion of breed purity observed in some breeds.

The possibilities for ammonium ions removal from aqueous solutions by natural and NaCl pretreated Bulgarian clinoptilolite from Beli plast deposit were studied. Experiments were carried out using batch method. The adsorption of NH4(+) was investigated as a function of the solution pH, dosage of adsorbent, initial ammonium concentration and temperature. The results clearly showed that the treatment with NaCl improved both the adsorption capacity and the removal efficiency of natural clinoptilolite. The equilibrium experimental data for adsorbed NH4(+) ions on clinoptilolite samples were correlated better by the Langmuir isotherm model. The maximum adsorption capacities for ammonium ions shown by natural and pretreated clinoptilolites (CL_Na and CL_Na(t)) were 7.85, 12.29 and 18.40 mg/g, respectively. The results indicated a significant potential of the natural and conditioned clinoptilolites as adsorbents for ammonium removal.

The experiments are carried out on chloralose-anaesthesized sheep (50-70 mg/kg). The increase in the force, frequency and duration of the stimulating impulses in a geometric progression leads to an increase in the amplitude of the contractions in all sections of the complex stomach. The amplitude and nature of the evoked contractions for one and the same parameters of stimulation are different in the different sections. The latency of the response in the reticulum is always shorter and its contractions increase faster than in the other sections. The relaxation of the muscles after elimination of the stimulation to the initial level is slowest in the rumen and in the case of high parameters of stimulation it takes more than 10 min.

The effect of histamine and serotonin is studied on strips of the two smooth-muscle layers from the different sections of the complex stomach. Histamine in concentration of 10(-9) to 10(-4) g/ml has no visible effect on preparations from the rumen and reticulum. In strips from the omasum as well as from the proximal and antral regions of the abomasum inhibitory effect is observed mainly with respect to the spontaneous phasic activity of the strips. Serotonin in concentrations of 10(-8) to 10(-4) g/ml has an excitatory effect in almost all preparations studied. Of the forestomach strips it is mostpronouced in rumen strips. The effect consists in an increase of the tone of the preparations. In the proximal region of the abomasum is effect also consists in a rise of the tone, while in strips from the antral region it causes a rise in the amplitude and frequency of the phasic contractions. Serotonin in the concentrations tested has an inhibitory effect only on omasum preparations.

Contractile responses to stimulation of nerve elements in smooth-muscle strips of complex sheep stomach suggest the existence of inhibitory and excitatory nerve structures in preparations from all compartments. Pharmacological analysis of the responses shows that they are mediated by cholinergic excitatory, noncholinergic excitatory and nonadrenergic inhibitory nerve elements. Comparison of the distribution of the cholinergic nerve structures shows that there are no essential differences between the different compartments. Differences are observed between strips cut in the direction of the two muscle layers, the effect of the cholinergic nerve elements being more pronounced in the longitudinal strips compared with the transverse ones. Noncholinergic excitatory effects of nerve stimulation are observed in all compartments of the complex stomach. Nonadrenergic nerve structures with inhibitory effect on the muscle strips are found in all compartments of the stomach. It is assumed that in the rumen they have spontaneous activity which inhibits the capacity of the smooth muscles in this part of the stomach for spontaneous phasic contractions.

Cataract prevalence in Bulgaria is a subject of current registration and of research studies. Our report deals with three basic sources: national statistics data, epidemiological study on cataract incidence, and clinical observation on risk factors. In 1985, 7.9 cataract cases per 1,000 population (over 15 years) have been registered. Cataract extractions increased from 6,972 (1980) to 8,050 (1984). Cataract prevalence study on 2.5 representative samples during the 1970 census in Bulgaria demonstrated 3.6% for urban and 2.5% for rural populations for 1 year of observation. The data showed a 10-fold increase when additional ophthalmologic examination of a given sample had been performed. The clinically based study of cataract characteristics and risk factors includes about 600 patients for a 1-year period. In this report the data according to sex and age distribution, type of cataract and the presence of systemic disease have been presented.