Година XXX, Книжка 6, 2021<<Архив>>
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STUDY OF COMPOSITIONS FOR SELECTIVE WATER ISOLATION IN GAS WELLS
A hydrophobic composition containing water repellents and highly volatile solvents is shown in this study to isolate water from the bottomhole formation zone of gas wells and reduce as much as possible the saturation of pore spaces with water. During injection...
Volatile solvents; Gas wells; Permeability; Water isolation; Porous media
МУТАЦИИ И ВАРИАНТИ НА КОРОНАВИРУСА SARS-COV-2, ПРИЧИНИТЕЛ НА COVID-19
През 2020 година коронавирусът SARS-CoV-2 предизвика пандемия с тежки последици за много страни. Кратко е описан жизненият цикъл на вируса. Обърнато е внимание, че намножаването на вирусния генетичен материал е съпроводено с възникването на мутации, което води...
коронавируси; варианти на SARS-CoV-2; варианти повод за тревога; нови варианти
SEMIEMPIRICAL QUANTUM CHEMICAL AND AB INTIO STUDY OF Co(II), Ni(II),Cu(II) AND Zn(II) COMPLEXES WITH THE AZO DYE DERIVED FROM 4-AMINO ANTIPYRINE AND 2,4-DIHYDROXY ACETOPHEONE
Semi-empirical quantum chemical calculation was made to study the nucleophilicity of the ligand and to study the mode of bonding between the ligand and the metal ions. The natural atomic charge at different atomic sites of the ligand has been calculated along...
Semiempirical study; Chem 3D Ultra; Natural atomic charge; Molecular polarisability
ON THE SOUND, PRODUCED BY A COIN, ROLLING IN A BALLOON
Balloons may be a thing children love playing with, but they also have different interesting physical properties such as the sound that is produced when something is put inside a balloon. The phenomenon of interest of this article is the one of gently rolling...
IYNT; buzzing sound; coin; balloon; frequency; velocity
ТРУДНИ ТЕМИ В УЧЕБНАТА ПРОГРАМА ПО ХИМИЯ ОТ ГЛЕДНА ТОЧКА НА УЧЕНИЦИТЕ
Химията често се възприема като труден предмет, а начинът, по който учениците възприемат ученето, влияе върху техните резултати. В изследването се търси информация от учениците за: темите от учебната програма по химия и опазване на околната среда (общозадължит...
Students’ Perceived difficulties; Chemistry curricula; Chemistry education
DEVELOPMENT OF THE CONCEPT OF ENTROPY: A SIMPLER ALTERNATIVE TO CARNOT CYCLE
The relationship between entropy and reversible heat and temperature is developed using a simple cycle, in which an ideal gas is subjected to isothermal expansion and compression and heated and cooled between states. The procedure is easily understood by stude...
Thermodynamics; Entropy; reversible work; reversible heat; irreversible process