Обучение по природни науки и върхови технологии

2017/2, стр. 275 - 286

STABILITY OF RJ-5 FUEL

Lemi Türker
E-mail: lturker@metu.edu.tr
Department of Chemistry
Middle East Technical University
06531 Ankara, Turkey
Serhat Variş

Резюме: In this work, the stability of a bicyclic high-energy-density fuel, RJ-5 (C14H18), has been inspected. The tendency of RJ-5 jet fuel to form hydroperoxide structure under storage conditions has been examined. The negative ∆G orxn values showed that oxidation of fuel through hydroperoxidation is a spontaneous process. It was shown that the bridgehead carbon atoms and the carbon atoms that link the norbornane structure with the other ring system are the vulnerable centers to hydroperoxidation because the corresponding hydroperoxides are quite low in total electronic energies. The thermodynamic calculations showed that these hydroperoxide structures may rearrange themselves to minimize their energy forming different molecules. These rearranged molecules have been identified using rearrangement mechanism in the literature. The probable rearrangement products were determined and confirmed by thermodynamic calculations. The heat of combustion values of RJ-5, hydroperoxides and rearrangement products of hydroperoxides have been calculated using T1 heat of formation data. The results showed that the formation of hydroperoxide molecules under storage conditions worsens the performance of RJ-5 jet fuel.

Ключови думи: jet fuel, RJ-5, oxidation, hydroperoxidation, rearrangement

Introduction

High energy liquid fuel has been employed for rockets along with jet engines such as turbo-jet, ram-jet, pulse jet and etc. In order to improve thrust force of rockets and jet engines, fuel having high combustion energy as much as possible per unit volume, i.e., liquid fuel having ‘high density and high heat of combustion’ is required. Moreover, since liquid fuel is supplied to combustion chambers through pipes, or used in combination with liquid oxygen, or employed for flying objects in ultra-high altitude region at low temperature, suitable viscosity and pour point are required for such liquid fuel. In addition, it is also necessary that liquid fuel should be non-corrosive to engines (Edwards, 2003; Chung et al., 1999; Wucherer & Wilson, 1998; Roy, 2000). RJ-5 is a fuel that satisfies these requirements.

Fig. 1. The formation of hydroperoxide by O2 molecule

RJ-5 is a bridged polycylic alkane molecule with the chemical formula C14H18 (Fig. 1). It is synthesized by reacting norbornadiene (which can be produced from acetylene and cyclopentadiene) over 15 wt % of a rhodium on carbon catalyst, followed by hydrogenation and isomerization to yield the product endo, endo-dihydrodinorbornadiene (RJ-5)1) (Harvey et al., 2010).

Fuel instability is a result of formation of hydroperoxy molecules in the fuel. Hydrocarbon fuels are vulnerable to degradation under long time, low-temperature storage conditions (storage stability) or under short time high-temperature stress (thermal oxidative stability). The major thermal oxidation may arise during flight conditions, where fuel assists as a coolant on its way to the combustion chamber. Minor thermal degradations may happen in nonoxidizing atmospheres, but the presence of oxygen or active species such as hydroperoxides tremendously accelerate the oxidative degradation initiating severe deviations in fuel character. The hydrocarbon structure, heteroatom concentration, oxygen concentration and the temperature are the key parameters in the rate of autoxidation of hydrocarbon fuel. If adequate oxygen is present in the medium, the concentration of hydroperoxides formed reaches to high levels. If the available oxygen is low, but the temperature is high, the hydroperoxide concentration is limited by free-radical decomposition. In this circumstance, fuel degradation can be related to both hydroperoxide formation and rearrangement (Watkins et al., 1999).

Hydroperoxide formation in fuel deteriorates elastomeric structure in aircraft fuel tank systems, which resulted in the loss of an airplane during the 1970s. After that accident, a project was proposed to shed some light on the hydroperoxide forming tendency of a hydrocarbon jet fuel under storage conditions (Nadler, 1980).

The partial oxidation of hydrocarbons through hydroperoxide formation is an initial point for the understanding of the cracking mechanisms in alkane compounds (Jensen et al., 1979; Blaine & Savage, 1991). We supposed that RJ-5 is a potential substance susceptible to oxidation through hydroperoxide formation. This has inspired us to investigate hydroperoxide formation of RJ-5, computationally. The biradical O2 molecule may easily cause any of C-H group to lose hydrogen radical and adds itself to the carbon radical of the molecule. The formed peroxy radical abstracts the hydrogen radical to form a hydroperoxide molecule as indicated in Fig. 1.

Method

The initial structure optimizations of RJ-5, hydroperoxide derivatives and rearrangement products were achieved by following the order: MM2 method, PM3 method, STO and HF 6-31G(d,p) and finally DFT-B3LYP at the level of 6-31G(d,p) were applied (Leach, 1997; Stewart, 1989a; 1989b; Kohl & Sham, 1965; Parr & Weetao, 1989). No imaginary frequencies have been observed in single point calculations. The total electronic energies were corrected for zero point vibrational energies (ZPE). The heat of formation of all the molecules were calculated by a T1 Thermochemical Recipe implemented in Spartan’08 (Ohlinget et al., 2009). All these computations were performed by using Spartan’08 package program at standard conditions of 298.15 K and 1.00 atm.2)

Results and discussion

The hydrogen and carbon atoms of RJ-5 are numbered as shown in Fig. 2. Numberings of the hydroperoxides have been done in the same manner. Table 1 indicates the labeling of the hydroperoxide molecules derived from the corresponding atoms.

Fig. 2. Labeling of hydrogen
and carbon atoms of RJ-5

The point group of RJ-5 molecule is C1. The molecule lacks symmetry and all the hydrogen atoms of the molecule are different (18 different hydrogen atoms). For that reason, in the present study, RJ-5 itself, 18 different hydroperoxides originated from RJ-5 and 12 rearrangement products have been considered theoretically. T1 thermochemical recipe has been utilized to calculate the heat of formation of RJ-5 (Ohlinget et al., 2009). The T1 heat of formation value of RJ-5 has been calculated as 130.81 kJ.mol-1, which indicates that the formation of the compound from its elements is an endothermic process. We have calculated the dipole moment of RJ-5 as 0.12 Debye. The fuel has been thought to be an almost nonpolar molecule.

Table 1. Labeling of the hydroperoxides derived from RJ-5, ZPE corrected total electronic energy and Go values of the molecules calculated at B3LYP 6-31G(d,p) level

The AtomsHydroperoxide LabelEtotal(kJ/mol)Go(kJ/mol)C1-OOH1A-1823001.13-1823094.38C1-OOH2B-1823002.78-1823095.96C2-OOH4C-1823010.94-1823103.54C3-OOH5D-1822989.80-1822958.26C3-OOH6E-1823005.88-1823099.14C4-OOH7F-1822989.77-1823082.42C4-OOH8G-1823005.97-1823099.25C5-OOH10H-1823010.87-1823103.43C6-OOH12I-1823000.90-1823092.93C7-OOH14J-1823001.08-1823093.12C8-OOH3K-1823011.33-1823104.08C9-OOH11L-1823005.16-1823097.98C10-OOH17M-1823011.54-1823104.36C11-OOH18N-1822987.30-1823080.12C12-OOH16O-1823017.14-1823079.99C13-OOH13P-1823000.97-1823094.14C13-OOH21R-1823000.95-1823093.98C14-OOH15S-1823003.30-1823096.35

The tendency of formation of RJ-5 hydroperoxides

RJ-5 is vulnerable to oxidation through hydroperoxide formation like all hydrocarbons (Hayashi et al., 1998) under storage conditions. This has directed us to study hydroperoxide formation of RJ-5, computationally. The route adopted in the current study is as follows: the biradical O2 molecule simply causes any C-H group of RJ-5 to lose a hydrogen radical forming RJ-5 radical and then bonds itself to that radical. The formed peroxy radical combines with the eliminated hydrogen radical to yield the hydroperoxide molecule as shown in Fig. 1.

Table 1 shows the labeling of the hydroperoxides originated from the corresponding atoms, their zero point energy (ZPE) corrected total electronic energies calculated at (B3LYP/6-31G(d,p)) level of theory. A molecule is supposed to be stable when total electronic energy value is low. When total electronic energy values of hydroperoxides are considered, the stability order is as follows: O>M>K>C>H>G>E>L>S>B>A>J>P>R>I>D>F>N. The molecules having hydroperoxy groups at tertiary carbon centers are lower in energy when compared to ones holding hydroperoxy groups at secondary carbon centers. The comparison of the total electronic energies of the hydroperoxide molecules enables to assign the “the most feasible carbon centers”. These are the potent carbons to be oxidized through hydroperoxidation. The bridgehead carbon atoms C2 and C5, the carbon centers that link the norbornane structure with the other ring system C,8 C10 and C12 are very prone to oxidation through hydroperoxidation because the corresponding hydroperoxides C, H, K, M and O are quite low in total electronic energies (Table 1). The carbon center C11 seems to be the least reasonable position for oxidation as a result of the highest total electronic energy of all.

Table 2 displays the ∆Go values for the transformation of RJ-5 to hydroperoxide molecules. ∆Go has beenrxn calculated as the difference between the Go values of the products (hydroperoxiderxn molecule) and the reactants (RJ-5 (Go= -1428379.67 kJ/mol) and o= -392584.96 kJ/mol) molecule) at B3LYP/6-31G(d,p) level. According to O(Gthe2 negative ∆Go values shown in Table 2, hydroperoxidation of any rxn site of RJ-5 is a spontaneous process. The probability of formation of hydroperoxides C, H, K and M is high due to larger negative ∆Go values than those of other rxn structures. Although “hydroperoxide O” seems to be thermodynamically the most stable of all, ∆Go value is not as low as those of C, H, K and M molecules. These rxn hydroperoxides have one mutual point. They all have the hydroperoxy groups on tertiary position.

Table 2. The ΔGrxn values for the hydroperoxidation of RJ-5 and relative ΔGrxn values

Hydroperoxide LabelΔGorxn(kJ/mol)Relative ΔGorxn(kJ/mol)

M -2139.72 0.00

K -2139.45 0.28

C -2138.91 0.81

H -2138.79 0.93

G -2134.62 5.11

E -2134.51 5.22

L -2133.35 6.37

S -2131.72 8.01

B -2131.33 8.39

A -2129.75 9.98

P -2129.50 10.22

R -2129.35 10.38

J -2128.48 11.24

I -2128.29 11.43

F -2117.78 21.94

N -2115.48 24.24

O -2115.36 24.36

Rearrangement of RJ-5 hydroperoxides

In this part of the study, the rearrangement of the most feasible hydroperoxides has been inspected. The hydroperoxides whose relative ∆Go values with to ∆Go of hydroperoxide M (from RJ-5 to respectthe corresponding hydroperoxiderxn molrxn ecule) are within the limit of 1 kJ/mol have been selected. The probabilities of formation of these hydroperoxide molecules are close to each other.

The meta stable hydroperoxide molecules tend to transform themselves to molecules having less total electronic energies. The carboxylic acid (ester) – alkane, alcohol - aldehyde and alcohol - ketone mechanisms have been suggested for hydroperoxide rearrangement in the literature (Türker & Variş, 2014; 2015; Türker et al., 2013) and have been taken into account in this work. Due to structural limitation of hydroperoxide molecules in the current study, only alcohol-ketone rearrangement mechanism has been applied to the RJ-5 Hydroperoxide molecules. In this mechanism, as the name designates, rearrangement of the hydroperoxide group yields an alcohol and an aldehyde group. This mechanism arises for the rearrangement of tertiary peroxides just as the ones in the present study. The choice of this mechanism is based on analytic information along with the distribution of products formed from the oxidative cracking of hydroperoxides (Câmara et al., 2006).

OH

OOHOOHOOHHydroperoxide-CC-P1C-P2OOC-P3H-P3Hydroperoxide-HHOOHOOH-P1OH-P2HOOH
OOHHydroperoxide-KOK-P1OHOHOK-P2OHOK-P3

Fig. 3. The rearrangement products of hydroperoxide molecules C, H, K and M

HO

Hydroperoxide-MOOHOM-P1OOM-P2HOOHM-P3

Presently, the rearrangements of the hydroperoxides C, H, K and M have been considered in view of the proposed mechanisms as previously stated. As seen from Fig. 3, we have made thermodynamic energy calculations on these twelve products over DFT optimized structures using B3LYP method and 6-31G(d,p) basis set. The ∆Go values for the conversion of hydroperoxide molecules to the products are shownrxn in Table 3. ∆Go values have been calculated as the difference between rxn the Go values of the products and the reactants. The first rearrangement product of hydroperoxide C is labeled as C-P1, second product is C-P2 and third one is C-P3. Other ones are labeled in the same way.

Hydroperoxide C holds the peroxy group at bridgehead carbon numbered as 2 (Fig. 2). It may transform itself to three different products (C-P1, C-P2 and C-P3). Since Gibbs free energy change (∆Go ) for the formation of C-P1 (Fig. 3) is more rxn negative than those of other reactions, Hydroperoxide-C molecule thermodynamically prefers to convert itself to that molecule. Also, the total electronic energy of C-P1 is lower than those of the C-P2 and C-P3. Therefore, C-P1 has been found to be the most feasible rearrangement product of Hydroperoxide C in terms of the thermodynamic considerations.

Table 3. The ZPE corrected total energy values and ∆Go values of the reacrxn tions in Fig. 3

Rearrangement ProductsEtotal(kJ/mol)ΔGorxn(kJ/mol)C-P1-1823294.44-285.62C-P2-1823293.51-285.16C-P3-1823292.23-282.97H-P1-1823293.39-284.91H-P2-1823275.58-267.16H-P3-1823293.80-285.38K-P1-1823264.48-254.86K-P2-1823282.38-271.93K-P3-1823228.61-219.07M-P1-1823263.00-252.54M-P2-1823284.42-273.81M-P3-1823261.87-251.45

Another bridgehead hydroperoxide is “H”. There are also three rearrangement products for hydroperoxide-H. Since ∆Go for the formation of C-P3 is more neg

rxn

ative than those of other products, this hydroperoxide molecule prefers to change itself to C-P3. Furthermore, the total electronic energy of C-P3 is lower than other molecules, which shows the stability of C-P3 molecule.

The hydoperoxide K holds the hydroperoxy group on the tertiary carbon that connects the norbornane structure with the other ring system. This hydroperoxide tends to transform itself to K-P2 molecule due to more negative ∆Go . Also, this rxn product seems more stable than other ones considering the total electronic energy. Likewise, hydroperoxide M also has the peroxy group on the other tertiary carbon that connects the norbornane structure with the other ring system. It is likely to

rearrange itself to M-P2 molecule considering ∆Go values. rxn

The eect of hydroperoxidation on the heat of combustion of RJ-5

The heat of combustion (∆Ho ) is the energy released as heat when a compound c undergoes complete combustion with O2under standard conditions. The chemical reaction is typically a hydrocarbon reacting with oxygen to produce carbon dioxide, water and heat. The heat released is expressed in kJ/mol. ∆Ho can be calculated taking the difference between the heat of formation (∆Hof ) of thec products and the reactants considering stoichiometry of the combustion reaction.

The complete combustion of RJ-5 (C14H18) and RJ-5 hydroperoxide (C14H18O2 ) is as follows:

C14H18(g)+ 18.5O2(g) à 14CO2(g) + 9H2O(g) + Q (I)

C14H18O2(g)+ 16.5O2(g) à 14CO2(g) + 9H2O(g) +Q (II)

The heat of formation (∆Ho) values of each species in above reactions should be known for the determination fof the ∆Hc o. ∆H f o has been calculated by T 1 Thermochemical Recipe implemented in Spartan’08 (Ohlimget et al, 2009). It follows the G3(MP2) recipe, by substituting an HF/6-31G(d) for the MP2/6-31G* geometry, eliminating both the HF/6-31G(d) frequency and QCISD(T)/6-31G(d) energy and approximating the MP2/G3MP2 large energy using dual basis set RI-MP2 techniques (Ohlimget et al, 2009). It produces reasonable results which are comparable to experimental values. Table 4 shows the T1 heat of formation values of the molecules. The data in the parenthesis are the literature values. The calculated values for CO2, H2 O and RJ-5 are quite close to the actual values. This consistency increases the reliability of the T1 method employed in the present work.

Table o of combustion (∆Ho ) and Relative (∆Ho4.The T1heat offormation(∆H), heat) values for the molecules in (kJ/mol)f c c

MoleculeFormulaT1∆Hof(kJ/mol)∆Hoc(kJ/mol)Relative∆Hoc(kJ/mol)

Carbon -406.42
DioxideCO₂ (-393.52)* -

-237.61
Water H2O - (-241.83)*

-7959.18 RJ-5 C₁₄H₁₈ 130.81 (134.7)**(7.8x103kJ/mol)** 0.00

C C₁₄H₁₈O₂ 33.62 -7861.99 97.19

H C₁₄H₁₈O₂ 33.63 -7862.00 97.18

K C₁₄H₁₈O₂ 32.22 -7860.59 98.59

M C₁₄H₁₈O₂ 32.06 -7860.43 98.75

C-P1 C₁₄H₁₈O₂ -239.98 -7588.39 370.79

C-P2 C₁₄H₁₈O₂ -236.53 -7591.84 367.34

C-P3 C₁₄H₁₈O₂ -233.68 -7594.69 364.49

H-P1 C₁₄H₁₈O₂ -239.84 -7588.53 370.65

H-P2 C₁₄H₁₈O₂ -217.75 -7610.62 348.56

H-P3 C₁₄H₁₈O₂ -228.30 -7600.07 359.11

K-P1 C₁₄H₁₈O₂ -231.11 -7597.26 361.92

K-P2 C₁₄H₁₈O₂ -228.09 -7600.28 358.90

K-P3 C₁₄H₁₈O₂ -169.07 -7659.30 299.88

M-P1 C₁₄H₁₈O₂ -208.8 -7619.57 339.61

M-P2 C₁₄H₁₈O₂ -226.99 -7601.38 357.80 M-P3C₁₄H₁₈O₂-201.59-7626.78332.40*Experimental values (Atkins & De Paola, 2006)

** Experimental values (Osmont et al., 2006)

The heat of combustion o value for RJ-5 is calculated as -7959.18 kJ/mol. The literature value has been (∆H)reportedc as -7.8x103 kJ/mol (Osmont et al., 2006). As seen from the table, formation of hydroperoxide molecules decreases the heat of combustion by 97 kJ/mol. The formation of rearrangement products (containing ketone and alcohol groups) from corresponding hydroperoxides causes a decrease of about 330 – 370 kJ/mol in the heat of combustion. The results in Table 4 numerically indicate the deterioration of performance of RJ-5 jet fuel due to hydroperoxidation.

Conclusion

In this work, the stability of RJ-5 (C14 H18), which is a bicyclic high-energy-density fuel, has been inspected. Since hydroperoxide concentration has been found to be a factor in fuel instability, oxidation of RJ-5 through hydroperoxidation mechanism has been discussed based on Density Functional Theory (DFT) calculations. The results showed that the bridgehead carbon atoms (C2 and C5) and the carbons that link the norbornane structure with the other ring system (C8 and C10) are found susceptible to oxidation through hydroperoxidation because the corresponding hydroperoxides C, H, K and M are quite low in total electronic energies. The hydoperoxide whose relative ∆Go values (from RJ-5 to the hydoperoxide C, H, K and M) rxn are within the limit of 1 kJ/mol have been considered. The rearrangement of these molecules has been questioned. The meta stable hydroperoxide molecules tend to convert themselves to molecules having both ketone and alcohol group of lower energy. The most feasible rearrangement products have been determined considering

∆Go values. The heat of combustion of RJ-5, hydroperoxides and rearrangement rxn

products of hydroperoxides have been calculated using T1 heat of formation data.

The calculations showed that the formation of hydroperoxide molecules during storage conditions deteriorates the heat of combustion of RJ-5 jet fuel.

NOTES

1. U.S. Patent 3,377,398; Apr. 9, 1968.

2. http://downloads.wavefun.com/Spartan08Manual_New.pdf

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ВЛИЯНИЕ НА МАРИНАТИТЕ ВЪРХУ МЕСОТО

Емил Мирчев, Галя Петрова

АНАЛИЗ НА ПРИРОДНИ ВОДИ В ОБЩИНА СЛИВЕН

Никола Урумов, Анелия Иванова

ТРИНАДЕСЕТИЯТ ЕЛЕМЕНТ – СПАСИТЕЛ ИЛИ ТИХ РАЗРУШИТЕЛ?

Виктория Дечкова, Никола Велчев, Нели Иванова

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MATHEMATICAL MODELLING OF THE TRANSMISSION DYNAMICS OF PNEUMONIA AND MENINGITIS COINFECTION WITH VACCINATION

Deborah O. Daniel, Sefiu A. Onitilo, Omolade B. Benjamin, Ayoola A. Olasunkanmi

2024 година
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2023 година
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ПОДКАСТ – КОГА, АКО НЕ СЕГА?

Христо Чукурлиев

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2022 година
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METEOROLOGICAL DETERMINANTS OF COVID-19 DISEASE: A LITERATURE REVIEW

Z. Mateeva, E. Batchvarova, Z. Spasova, I. Ivanov, B. Kazakov, S. Matev, A. Simidchiev, A. Kitev

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MATHEMATICAL MODELLING OF THE TRANSMISSION MECHANISM OF PLAMODIUM FALCIPARUM

Onitilo S. A, Usman M. A., Daniel D. O. Odetunde O. S., Ogunwobi Z. O., Hammed F. A., Olubanwo O. O., Ajani A. S., Sanusi A. S., Haruna A. H.

ПОСТАНОВКА ЗА ИЗМЕРВАНЕ СКОРОСТТА НА ЗВУКА ВЪВ ВЪЗДУХ

Станислав Сланев, Хафизе Шабан, Шебнем Шабан, Анета Маринова

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MAGNETIC PROPERTIES

Sofija Blagojević, Lana Vujanović, Andreana Kovačević Ćurić

„TAP, TAP WATER“ QUANTUM TUNNELING DEMONSTRATION

Katarina Borković, Andreana Kovačević Ćurić

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КОМЕТИТЕ – I ЧАСТ

Пенчо Маркишки

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DISTANCE LEARNING: HOMEMADE COLLOIDAL SILVER

Ana Sofía Covarrubias-Montero, Jorge G. Ibanez

2021 година
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STUDY OF COMPOSITIONS FOR SELECTIVE WATER ISOLATION IN GAS WELLS

Al-Obaidi S.H., Hofmann M., Smirnov V.I., Khalaf F.H., Alwan H.H.

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POTENTIAL APPLICATIONS OF ANTIBACTERIAL COMPOUNDS IN EDIBLE COATING AS FISH PRESERVATIVE

Maulidan Firdaus, Desy Nila Rahmana, Diah Fitri Carolina, Nisrina Rahma Firdausi, Zulfaa Afiifah, Berlian Ayu Rismawati Sugiarto

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INVESTIGATION OF 238U, 234U AND 210PO CONTENT IN SELECTED BULGARIAN DRINKING WATER

Bozhidar Slavchev, Elena Geleva, Blagorodka Veleva, Hristo Protohristov, Lyuben Dobrev, Desislava Dimitrova, Vladimir Bashev, Dimitar Tonev

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DEMONSTRATION OF DAMPED ELECTRICAL OSCILLATIONS

Elena Grebenakova, Stojan Manolev

2020 година
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ДОЦ. Д-Р МАРЧЕЛ КОСТОВ КОСТОВ ЖИВОТ И ТВОРЧЕСТВО

Здравка Костова, Елена Георгиева

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JACOB’S LADDER FOR THE PHYSICS CLASSROOM

Kristijan Shishkoski, Vera Zoroska

КАЛЦИЙ, ФОСФОР И ДРУГИ ФАКТОРИ ЗА КОСТНО ЗДРАВЕ

Радка Томова, Светла Асенова, Павлина Косева

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MATHEMATICAL MODELING OF 2019 NOVEL CORONAVIRUS (2019 – NCOV) PANDEMIC IN NIGERIA

Sefiu A. Onitilo, Mustapha A. Usman, Olutunde S. Odetunde, Fatai A. Hammed, Zacheous O. Ogunwobi, Hammed A. Haruna, Deborah O. Daniel

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WATER PURIFICATION WITH LASER RADIATION

Lyubomir Lazov, Hristina Deneva, Galina Gencheva

2019 година
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LASER MICRO-PERFORATION AND FIELDS OF APPLICATION

Hristina Deneva, Lyubomir Lazov, Edmunds Teirumnieks

ПРОЦЕСЪТ ДИФУЗИЯ – ОСНОВА НА ДИАЛИЗАТА

Берна Сабит, Джемиле Дервиш, Мая Никова, Йорданка Енева

IN VITRO EVALUATION OF THE ANTIOXIDANT PROPERTIES OF OLIVE LEAF EXTRACTS – CAPSULES VERSUS POWDER

Hugo Saint-James, Gergana Bekova, Zhanina Guberkova, Nadya Hristova-Avakumova, Liliya Atanasova, Svobodan Alexandrov, Trayko Traykov, Vera Hadjimitova

Бележки върху нормативното осигуряване на оценяването в процеса

БЕЛЕЖКИ ВЪРХУ НОРМАТИВНОТО ОСИГУРЯВАНЕ, НА ОЦЕНЯВАНЕТО В ПРОЦЕСА НА ОБУЧЕНИЕТО

ТЕХНОЛОГИЯ

Б. В. Тошев

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ON THE GENETIC TIES BETWEEN EUROPEAN NATIONS

Jordan Tabov, Nevena Sabeva-Koleva, Georgi Gachev

Иван Странски – майсторът на кристалния растеж [Ivan Stranski

ИВАН СТРАНСКИ – МАЙСТОРЪТ, НА КРИСТАЛНИЯ РАСТЕЖ

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CHEMOMETRIC ANALYSIS OF SCHOOL LIFE IN VARNA

Radka Tomova, Petinka Galcheva, Ivajlo Trajkov, Antoaneta Hineva, Stela Grigorova, Rumyana Slavova, Miglena Slavova

ЦИКЛИТЕ НА КРЕБС

Ивелин Кулев

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ПРИНЦИПИТЕ НА КАРИЕРНОТО РАЗВИТИЕ НА МЛАДИЯ УЧЕН

И. Панчева, М. Недялкова, С. Кирилова, П. Петков, В. Симеонов

UTILISATION OF THE STATIC EVANS METHOD TO MEASURE MAGNETIC SUSCEPTIBILITIES OF TRANSITION METAL ACETYLACETONATE COMPLEXES AS PART OF AN UNDERGRADUATE INORGANIC LABORATORY CLASS

Anton Dobzhenetskiy, Callum A. Gater, Alexander T. M. Wilcock, Stuart K. Langley, Rachel M. Brignall, David C. Williamson, Ryan E. Mewis

THE 100

Maria Atanassova, Radoslav Angelov

A TALE OF SEVEN SCIENTISTS

Scerri, E.R. (2016). A Tale of Seven Scientists and a New Philosophy of Science.

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DEVELOPMENT OF A LESSON PLAN ON THE TEACHING OF MODULE “WATER CONDUCTIVITY”

A. Thysiadou, S. Christoforidis, P. Giannakoudakis

AMPEROMETRIC NITRIC OXIDE SENSOR BASED ON MWCNT CHROMIUM(III) OXIDE NANOCOMPOSITE

Arsim Maloku, Epir Qeriqi, Liridon S. Berisha, Ilir Mazreku, Tahir Arbneshi, Kurt Kalcher

THE EFFECT OF AGING TIME ON Mg/Al HYDROTALCITES STRUCTURES

Eddy Heraldy, Triyono, Sri Juari Santosa, Karna Wijaya, Shogo Shimazu

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A CONTENT ANALYSIS OF THE RESULTS FROM THE STATE MATRICULATION EXAMINATION IN MATHEMATICS

Elena Karashtranova, Nikolay Karashtranov, Vladimir Vladimirov

SOME CONCEPTS FROM PROBABILITY AND STATISTICS AND OPPORTUNITIES TO INTEGRATE THEM IN TEACHING NATURAL SCIENCES

Elena Karashtranova, Nikolay Karashtranov, Nadezhda Borisova, Dafina Kostadinova

45. МЕЖДУНАРОДНА ОЛИМПИАДА ПО ХИМИЯ

Донка Ташева, Пенка Василева

2018 година
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ЗДРАВЕ И ОКОЛНА СРЕДА

Кадрие Шукри, Светлана Великова, Едис Мехмед

РОБОТИКА ЗА НАЧИНАЕЩИ ЕНТУСИАСТИ

Даниела Узунова, Борис Велковски, Илко Симеонов, Владислав Шабански, Димитър Колев

DESIGN AND DOCKING STUDIES OF HIS-LEU ANALOGUES AS POTENTIOAL ACE INHIBITORS

Rumen Georgiev, , Tatyana Dzimbova, Atanas Chapkanov

X-RAY DIFFRACTION STUDY OF M 2 Zn(TeО3)2 (M - Na, K) ТELLURIDE

Kenzhebek T. Rustembekov, Mitko Stoev, Aitolkyn A. Toibek

CALIBRATION OF GC/MS METHOD FOR DETERMINATION OF PHTHALATES

N. Dineva, I. Givechev, D. Tanev, D. Danalev

ELECTROSYNTHESIS OF CADMIUM SELENIDE NANOPARTICLES WITH SIMULTANEOUS EXTRACTION INTO P-XYLENE

S. S. Fomanyuk, V. O. Smilyk, G. Y. Kolbasov, I. A. Rusetskyi, T. A. Mirnaya

БИОЛОГИЧЕН АСПЕКТ НА РЕКАНАЛИЗАЦИЯ С ВЕНОЗНА ТРОМБОЛИЗА

Мариела Филипова, Даниела Попова, Стоян Везенков

CHEMISTRY: BULGARIAN JOURNAL OF SCIENCE EDUCATION ПРИРОДНИТЕ НАУКИ В ОБРАЗОВАНИЕТО VOLUME 27 / ГОДИНА XXVII, 2018 ГОДИШНО СЪДЪРЖАНИЕ СТРАНИЦИ / PAGES КНИЖКА 1 / NUMBER 1: 1 – 152 КНИЖКА 2 / NUMBER 2: 153 – 312 КНИЖКА 3 / NUMBER 3: 313 – 472 КНИЖКА 4 / NUMBER 4: 473 – 632 КНИЖКА 5 / NUMBER 5: 633 – 792 КНИЖКА 6 / NUMBER 6: 793 – 952 КНИЖКА 1 / NUMBER 1: 1 – 152 КНИЖКА 2 / NUMBER 2: 153 – 312 КНИЖКА

(South Africa), A. Ali, M. Bashir (Pakistan) 266 – 278: j-j Coupled Atomic Terms for Nonequivalent Electrons of (n-1)fx and nd1 Configurations and Correlation with L-S Terms / P. L. Meena (India) 760 – 770: Methyl, тhe Smallest Alkyl Group with Stunning Effects / S. Moulay 771 – 776: The Fourth State of Matter / R. Tsekov

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ИМОБИЛИЗИРАНЕНАФРУКТОЗИЛТРАНСФЕРАЗА ВЪРХУКОМПОЗИТНИФИЛМИОТПОЛИМЛЕЧНА КИСЕЛИНА, КСАНТАН И ХИТОЗАН

Илия Илиев, Тонка Василева, Веселин Биволарски, Ася Виранева, Иван Бодуров, Мария Марудова, Теменужка Йовчева

ELECTRICAL IMPEDANCE SPECTROSCOPY OF GRAPHENE-E7 LIQUID-CRYSTAL NANOCOMPOSITE

Todor Vlakhov, Yordan Marinov, Georgi. Hadjichristov, Alexander Petrov

ON THE POSSIBILITY TO ANALYZE AMBIENT NOISERECORDED BYAMOBILEDEVICETHROUGH THE H/V SPECTRAL RATIO TECHNIQUE

Dragomir Gospodinov, Delko Zlatanski, Boyko Ranguelov, Alexander Kandilarov

RHEOLOGICAL PROPERTIES OF BATTER FOR GLUTEN FREE BREAD

G. Zsivanovits, D. Iserliyska, M. Momchilova, M. Marudova

ПОЛУЧАВАНЕ НА ПОЛИЕЛЕКТРОЛИТНИ КОМПЛЕКСИ ОТ ХИТОЗАН И КАЗЕИН

Антоанета Маринова, Теменужка Йовчева, Ася Виранева, Иван Бодуров, Мария Марудова

CHEMILUMINESCENT AND PHOTOMETRIC DETERMINATION OF THE ANTIOXIDANT ACTIVITY OF COCOON EXTRACTS

Y. Evtimova, V. Mihailova, L. A. Atanasova, N. G. Hristova-Avakumova, M. V. Panayotov, V. A. Hadjimitova

ИЗСЛЕДОВАТЕЛСКИ ПРАКТИКУМ

Ивелина Димитрова, Гошо Гоев, Савина Георгиева, Цвета Цанова, Любомира Иванова, Борислав Георгиев

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PARAMETRIC INTERACTION OF OPTICAL PULSES IN NONLINEAR ISOTROPIC MEDIUM

A. Dakova, V. Slavchev, D. Dakova, L. Kovachev

ДЕЙСТВИЕ НА ГАМА-ЛЪЧИТЕ ВЪРХУ ДЕЗОКСИРИБОНУКЛЕИНОВАТА КИСЕЛИНА

Мирела Вачева, Хари Стефанов, Йоана Гвоздейкова, Йорданка Енева

RADIATION PROTECTION

Natasha Ivanova, Bistra Manusheva

СТАБИЛНОСТ НА ЕМУЛСИИ ОТ ТИПА МАСЛО/ ВОДА С КОНЮГИРАНА ЛИНОЛОВА КИСЕЛИНА

И. Милкова-Томова, Д. Бухалова, К. Николова, Й. Алексиева, И. Минчев, Г. Рунтолев

THE EFFECT OF EXTRA VIRGIN OLIVE OIL ON THE HUMAN BODY AND QUALITY CONTROL BY USING OPTICAL METHODS

Carsten Tottmann, Valentin Hedderich, Poli Radusheva, Krastena Nikolova

ИНФРАЧЕРВЕНА ТЕРМОГРАФИЯ ЗА ДИАГНОСТИКА НА ФОКАЛНА ИНФЕКЦИЯ

Рая Грозданова-Узунова, Тодор Узунов, Пепа Узунова

ЕЛЕКТРИЧНИ СВОЙСТВА НА КОМПОЗИТНИ ФИЛМИ ОТ ПОЛИМЛЕЧНА КИСЕЛИНА

Ася Виранева, Иван Бодуров, Теменужка Йовчева

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ТРИ ИДЕИ ЗА ЕФЕКТИВНО ОБУЧЕНИЕ

Гергана Карафезиева

МАГИЯТА НА ТВОРЧЕСТВОТО КАТО ПЪТ НА ЕСТЕСТВЕНО УЧЕНЕ В УЧЕБНИЯ ПРОЦЕС

Гергана Добрева, Жаклин Жекова, Михаела Чонос

ОБУЧЕНИЕ ПО ПРИРОДНИ НАУКИ ЧРЕЗ МИСЛОВНИ КАРТИ

Виолета Стоянова, Павлина Георгиева

ИГРА НА ДОМИНО В ЧАС ПО ФИЗИКА

Росица Кичукова, Ценка Маринова

ПРОБЛЕМИ ПРИ ОБУЧЕНИЕТО ПО ФИЗИКА ВЪВ ВВМУ „Н. Й. ВАПЦАРОВ“

А. Христова, Г. Вангелов, И. Ташев, М. Димидов

ИЗГРАЖДАНЕ НА СИСТЕМА ОТ УЧЕБНИ ИНТЕРНЕТ РЕСУРСИ ПО ФИЗИКА И ОЦЕНКА НА ДИДАКТИЧЕСКАТА ИМ СТОЙНОСТ

Желязка Райкова, Георги Вулджев, Наталия Монева, Нели Комсалова, Айше Наби

ИНОВАЦИИ В БОРБАТА С ТУМОРНИ ОБРАЗУВАНИЯ – ЛЕЧЕНИЕ ЧРЕЗ БРАХИТЕРАПИЯ

Георги Върбанов, Радостин Михайлов, Деница Симеонова, Йорданка Енева

NATURAL RADIONUCLIDES IN DRINKING WATER

Natasha Ivanova, Bistra Manusheva

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АДАПТИРАНЕ НА ОБРАЗОВАНИЕТО ДНЕС ЗА УТРЕШНИЯ ДЕН

И. Панчева, М. Недялкова, П. Петков, Х. Александров, В. Симеонов

STRUCTURAL ELUCIDATION OF UNKNOWNS: A SPECTROSCOPIC INVESTIGATION WITH AN EMPHASIS ON 1D AND 2D 1H NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Vittorio Caprio, Andrew S. McLachlan, Oliver B. Sutcliffe, David C. Williamson, Ryan E. Mewis

j-j Coupled Atomic Terms for Nonequivalent Electrons of (n-1)f

j-jCOUPLEDATOMICTERMSFORNONEQUIVALENT, ELECTRONS OF (n-f X nd CONFIGURATIONS AND, CORRELATION WITH L-S TERMS

INTEGRATED ENGINEERING EDUCATION: THE ROLE OF ANALYSIS OF STUDENTS’ NEEDS

Veselina Kolarski, Dancho Danalev, Senia Terzieva

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ZAGREB CONNECTION INDICES OF TiO2 NANOTUBES

Sohaib Khalid, Johan Kok, Akbar Ali, Mohsin Bashir

SYNTHESIS OF NEW 3-[(CHROMEN-3-YL)ETHYLIDENEAMINO]-PHENYL]-THIAZOLIDIN-4ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Naser Troni, Hamit Ismaili, Malesore Pllana, Musaj Pacarizi, Veprim Thaçi, Gjyle Mulliqi-Osmani

2017 година
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GEOECOLOGICAL ANALYSIS OF INDUSTRIAL CITIES: ON THE EXAMPLE OF AKTOBE AGGLOMERATION

Zharas Berdenov, Erbolat Mendibaev, Talgat Salihov, Kazhmurat Akhmedenov, Gulshat Ataeva

TECHNOGENESIS OF GEOECOLOGICAL SYSTEMS OF NORTHEN KAZAKHSTAN: PROGRESS, DEVELOPMENT AND EVOLUTION

Kulchichan Dzhanaleyeva, Gulnur Mazhitova, Altyn Zhanguzhina, Zharas Berdenov, Tursynkul Bazarbayeva, Emin Atasoy

СПИСАНИЕ ПРОСВѢТА

Списание „Просвета“ е орган на Просветния съюз в България. Списанието е излизало всеки месец без юли и август. Годишният том съдържа 1280 стра- ници. Списанието се издава от комитет, а главен редактор от 1935 до 1943 г. е проф. Петър Мутафчиев, историк византолог и специалист по средновеков-

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47-А НАЦИОНАЛНА КОНФЕРЕНЦИЯ НА УЧИТЕЛИТЕ ПО ХИМИЯ

В последните години тези традиционни за българското учителство конфе- ренции се организират от Българското дружество по химическо образование и история и философия на химията. То е асоцииран член на Съюза на химици- те в България, който пък е член на Европейската асоциация на химическите и

JOURNALS OF INTEREST: A REVIEW (2016)

BULGARIAN JOURNAL OF SCIENCE AND EDUCATION POLICY ISSN 1313-1958 (print) ISSN 1313-9118 (online) http://bjsep.org

INVESTIGATING THE ABILITY OF 8

Marina Stojanovska, Vladimir M. Petruševski

SYNTHESIS OF TiO -M (Cd, Co, Mn)

Candra Purnawan, Sayekti Wahyuningsih, Dwita Nur Aisyah

EFFECT OF DIFFERENT CADMIUM CONCENTRATION ON SOME BIOCHEMICAL PARAMETERS IN ‘ISA BROWN’ HYBRID CHICKEN

Imer Haziri, Adem Rama, Fatgzim Latifi, Dorjana Beqiraj-Kalamishi, Ibrahim Mehmeti, Arben Haziri

PHYTOCHEMICAL AND IN VITRO ANTIOXIDANT STUDIES OF PRIMULA VERIS (L.) GROWING WILD IN KOSOVO

Ibrahim Rudhani, Florentina Raci, Hamide Ibrahimi, Arben Mehmeti, Ariana Kameri, Fatmir Faiku, Majlinda Daci, Sevdije Govori, Arben Haziri

ПЕДАГОГИЧЕСКА ПОЕМА

Преди година-две заедно с директора на Националното издателство „Аз- буки“ д-р Надя Кантарева-Барух посетихме няколко училища в Родопите. В едно от тях ни посрещнаха в голямата учителска стая. По стените ѝ имаше големи портрети на видни педагози, а под тях – художествено написани умни мисли, които те по някакъв повод са казали. На централно място бе портретът на Антон Семьонович Макаренко (1888 – 1939). Попитах учителките кой е Макаренко – те посрещнаха въпроса ми с мълчание. А някога, в г

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„СИМВОЛНИЯТ КАПИТАЛ“ НА БЪЛГАРСКОТО УЧИЛИЩЕ

Николай Цанков, Веска Гювийска

KINETICS OF PHOTO-ELECTRO-ASSISTED DEGRADATION OF REMAZOL RED 5B

Fitria Rahmawati, Tri Martini, Nina Iswati

ALLELOPATHIC AND IN VITRO ANTICANCER ACTIVITY OF STEVIA AND CHIA

Asya Dragoeva, Vanya Koleva, Zheni Stoyanova, Eli Zayova, Selime Ali

NOVEL HETEROARYLAMINO-CHROMEN-2-ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Naser Troni, Hamit Ismaili, Gjyle Mulliqi-Osmani, Veprim Thaçi

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Quantum Connement of Mobile Na+ Ions in Sodium Silicate Glassy

QUANTUM CONFINEMENT OF MOBILE Na + IONS, IN SODIUM SILICATE GLASSY NANOPARTICLES

OPTIMIZATION OF ENGINE OIL FORMULATION USING RESPONSE SURFACE METHODOLOGY AND GENETIC ALGORITHM: A COMPARATIVE STUDY

Behnaz Azmoon, Abolfazl Semnani, Ramin Jaberzadeh Ansari, Hamid Shakoori Langeroodi, Mahboube Shirani, Shima Ghanavati Nasab

EVALUATION OF ANTIBACTERIAL ACTIVITY OF DIFFERENT SOLVENT EXTRACTS OF TEUCRIUM CHAMAEDRYS (L.) GROWING WILD IN KOSOVO

Arben Haziri, Fatmir Faiku, Roze Berisha, Ibrahim Mehmeti, Sevdije Govori, Imer Haziri

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COMPUTER SIMULATORS: APPLICATION FOR GRADUATES’ADAPTATION AT OIL AND GAS REFINERIES

Irena O. Dolganova, Igor M. Dolganov, Kseniya A. Vasyuchka

SYNTHESIS OF NEW [(3-NITRO-2-OXO-2H-CHROMEN4-YLAMINO)-PHENYL]-PHENYL-TRIAZOLIDIN-4-ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Hamit Ismaili, Idriz Vehapi, Naser Troni, Gjyle Mulliqi-Osmani, Veprim Thaçi

STABILITY OF RJ-5 FUEL

Lemi Türker, Serhat Variş

A STUDY OF BEGLIKTASH MEGALITHIC COMPLEX

Diana Kjurkchieva, Evgeni Stoykov, Sabin Ivanov, Borislav Borisov, Hristo Hristov, Pencho Kyurkchiev, Dimitar Vladev, Irina Ivanova

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2016 година
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THE EFFECT OF KOH AND KCL ADDITION TO THE DESTILATION OF ETHANOL-WATER MIXTURE

Khoirina Dwi Nugrahaningtyas, Fitria Rahmawati, Avrina Kumalasari

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ОЦЕНЯВАНЕ ЛИЧНОСТТА НА УЧЕНИКА

Министерството на народното просвещение е направило допълне- ния към Правилника за гимназиите (ДВ, бр. 242 от 30 октомври 1941 г.), според които в бъдеще ще се оценяват следните прояви на учениците: (1) трудолюбие; (2) ред, точност и изпълнителност; (3) благовъзпитаност; (4) народностни прояви. Трудолюбието ще се оценява с бележките „образцово“, „добро“, „незадо- волително“. С „образцово“ ще се оценяват учениците, които с любов и по- стоянство извършват всяка възложена им ил

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VOLTAMMERIC SENSOR FOR NITROPHENOLS BASED ON SCREEN-PRINTED ELECTRODE MODIFIED WITH REDUCED GRAPHENE OXIDE

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ИЗСЛЕДВАНЕ НА ПРОФЕСИОНАЛНО-ПЕДАГОГИЧЕСКАТА РЕФЛЕКСИЯ НА УЧИТЕЛЯ ПО БИОЛОГИЯ (ЧАСТ ВТОРА)

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На 8 март 2016 г. в голямата зала на Националния политехнически музей в София фондация „Вигория“ връчи годишните си награди – почетен плакет „Златна детелина“. Тази награда се дава за цялостна професионална и творче- ска изява на личности с особени заслуги към обществото в трите направления на фондация „Вигория“ – образование, екология, култура. Наградата цели да се даде израз на признателност за високи постижения на личности, които на професионално равнище и на доброволни начала са рабо

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ПО ПЪТЯ

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TEACHER’S ACCEPTANCE OF STUDENTS WITH DISABILITY

Daniela Dimitrova-Radojchikj, Natasha Chichevska-Jovanova

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Книжка 4
БЛАГОДАРЯ ВИ!

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SYNTHESIS OF FLUORINATED HYDROXYCINNAMOYL DERIVATIVES OF ANTI-INFLUENZA DRUGS AND THEIR BIOLOGICAL ACTIVITY

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Книжка 2
TEACHING CHEMISTRY AT TECHNICAL UNIVERSITY

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РУМЕН ЛЮБОМИРОВ ДОЙЧЕВ (1938 – 1999)

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145 ГОДИНИ БЪЛГАРСКА АКАДЕМИЯ НА НАУКИТЕ

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V. Romanenko, G. Nikitina Academy of Information Technologies in Education, Russia

ALLELOPATHIC AND CYTOTOXIC ACTIVITY OF ORIGANUM VULGARE SSP. VULGARE GROWING WILD IN BULGARIA

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GENDER ISSUES OF UKRAINIAN HIGHER EDUCATION

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44

Донка Ташева, Пенка Василева

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SCIENTIX – OБЩНОСТ ЗА НАУЧНО ОБРАЗОВАНИЕ В ЕВРОПА

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Книжка 1
ОБРАЗОВАНИЕ ЗА ПРИРОДОНАУЧНА ГРАМОТНОСТ

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DIFFERENTIAL TEACHING IN SCHOOL SCIENCE EDUCATION: CONCEPTUAL PRINCIPLES

G. Yuzbasheva Kherson Academy of Continuing Education, Ukraine

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Книжка 5

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Книжка 4
RECASTING THE DERIVATION OF THE CLAPEYRON EQUATION INTO A CONCEPTUALLY SIMPLER FORM

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Книжка 3
SIMULATION OF THE FATTY ACID SYNTHASE COMPLEX MECHANISM OF ACTION

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Книжка 2
Книжка 1
COLORFUL EXPERIMENTS FOR STUDENTS: SYNTHESIS OF INDIGO AND DERIVATIVES

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Книжка 6
ADDRESING STUDENTS’ MISCONCEPTIONS CONCERNING CHEMICAL REACTIONS AND SYMBOLIC REPRESENTATIONS

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КОНЦЕПТУАЛНА СХЕМА НА УЧИЛИЩНИЯ КУРС П О ХИМИЯ – МАКР О СКОПСКИ ПОДХОД

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