Обучение по природни науки и върхови технологии

2018/2, стр. 223 - 234

STRUCTURAL ELUCIDATION OF UNKNOWNS: A SPECTROSCOPIC INVESTIGATION WITH AN EMPHASIS ON 1D AND 2D \(^{1}\)H NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Vittorio Caprio
E-mail: v.caprio@mmu.ac.uk
School of Science and the Environment
Division of Chemistry and Environmental Science
Manchester Metropolitan University
John Dalton Building
Chester St.
Manchester M1 5GD UK
Andrew S. McLachlan
E-mail: Andy.McLachlan@oxinst.com
Oxford Instruments
Tubney Woods
Abingdon
Oxfordshire OX13 5QX UK
Oliver B. Sutcliffe
E-mail: o.sutcliffe@mmu.ac.uk
School of Science and the Environment
Division of Chemistry and Environmental Science
Manchester Metropolitan University
John Dalton Building
Chester St.
Manchester M1 5GD UK
David C. Williamson
E-mail: David.Williamson@oxinst.com
Oxford Instruments
Tubney Woods
Abingdon
Oxfordshire OX13 5QX UK
Ryan E. Mewis
E-mail: r.mewis@mmu.ac.uk
School of Science and the Environment
Division of Chemistry and Environmental Science
Manchester Metropolitan University
John Dalton Building
Chester St.
Manchester M1 5GD UK

Резюме: Nuclear Magnetic Resonance (NMR) spectroscopy is a widely used technique for structural elucidation. It is often used in conjunction with other complimentary analytical techniques such as infra-red (IR) and mass spectrometry (MS) to completely assign the chemical structure of molecules. For undergraduate students, gaining familiarity with NMR is often difficult as they rarely have the opportunity to collect this data for themselves; often they are just provided with spectra to interpret. We have developed an experiment that tasks students with obtaining 1D and 2D \(^{1}\)H NMR data of two unknowns, and then using \(^{13}\)C{1H} NMR, CHN elemental microanalysis, MS and IR data, to elucidate fully their two structures. The experiment provides students with an experiential learning opportunity for \(^{1}\)H NMR whilst also developing and strengthening their structural elucidation skills.

Ключови думи: second-year undergraduate; organic chemistry; hands-on learning; problem solving; NMR spectroscopy

Introduction

NMR (Nuclear Magnetic Resonance) is a powerful analytical technique; it enables the connectivity of atoms to be deduced and, by using this information, elucidate the structure of a compound. It is an integral technique that is utilised in research and design worldwide, particularly within the pharmaceutical industries for analysis of new drug compounds, but also in materials science, food analysis and clinical studies (Gerothanassis et al., 2002). Despite the inherent sensitivity issue associated with NMR, which is more evident at low magnetic field strengths, several companies have now developed benchtop NMR devices which are cheaper than their associated high-field, superconducting counterparts. A streamlined approach to the collection of NMR data has been taken by these companies, resulting in the devices being suitable for enabling students to collect NMR data with minimal input from instructors (Yearty et al., 2017; Zivkovic et al., 2017a; 2017b).

Typically, students are not exposed to NMR spectroscopy practically as much as other spectroscopic techniques, such as IR, even though the positive benefits of the inclusion of high-field FT-NMR in the undergraduate curriculum has been noted (Ball & Miller, 2002). Some laboratory facilitators have designed experiments to introduce high-school students to NMR spectroscopy using low-field NMR to increase exposure to the technique prior to entering tertiary education (Bonjour et al., 2015). NMR sites, such as the one at Trinity University which comprises spectral data of student samples from community colleges, have been utilised to provide students with the unprocessed free induction decay (FID) so that they may process the data to generate relevant spectra (Mills & Shanklin, 2011). However, this does not provide students with hands-on experience of data collection. Students can often have a perceived complexity of the technique, in that NMR is typically foreseen as a “black box” technique with students “simply click[ing] on a mouse button and collect[ing] a spectrum without fully understanding the mechanics of the instrument” (Lorigan et al., 2001). Although theoretical knowledge of NMR is important, actually conducting an NMR-based experiment helps improve student understanding as evidenced by post-lab qualitative student self-assessment and identical quantitative pre- and post-lab tests (Wagner et al., 2013).

NMR analysis can be used alongside other analytical techniques, such as thin layer chromatography, to monitor organic transformations. For example, the hydrogenation of curcumin using a hydrogenation flow reactor has been described (Wagner et al., 2013). Part of the practical experiment involved assigning the 1H NMR spectra of curcumin and its hydrogenated analogue, tetrahydrocurcumin. Both products have many structural features to demonstrate 1H NMR shifts, and the nuclei possess spin-spin couplings to help further elucidate their structures. Furthermore complex pulse sequences, such as DEPT (Distortionless Enhancement by Polarisation Transfer), have been employed for the identification of unknown alcohols in a second-year undergraduate course (Chamberlain, 2013).

Structural elucidation is an important skill that students continually develop throughout their undergraduate degree and beyond, mainly through enquiry-based learning (EBL). The use of EBL has been reported to increase the confidence of first-year chemistry students learning spectroscopy (Lucas & Rowley, 2011). Opportunities to apply these skills and develop them further must be provided through an undergraduate curriculum (Carroll et al., 2012; Cerrada & Laguna, 2005; Dávila & Widener, 2002; Grant & Latimer, 2003; Nazri et al., 2012; Walsh et al., 2012). Herein, we describe a practical experiment for second-year undergraduate students that has a focus on 1H NMR, but also utilises 13C{1H} NMR, CHN elemental microanalysis, IR and MS data to elucidate the two unknowns. The main pedagogical goals of this experiment are to: (i) enable students to make links between NMR theory and the “real world” collection of NMR data, analysis and interpretation from a practical perspective through experiential learning; (ii) demonstrate to students the power of NMR in the structural elucidation of organic compounds through the collection of 1D and 2D NMR data; (iii) demonstrate to students that analytical techniques should not be used in isolation but in tandem with one another in order to successfully elucidate the structures of molecules

General experiment and discussion

This experiment1) is intended to act as a support laboratory session for students as part of a core organic module in which NMR and other spectroscopic techniques are taught alongside organic chemistry that has as one of its many focuses the formation and reactions of enolates. Thus, the laboratory session is designed to link these two elements together so that students utilise knowledge from different parts of their course in order to complete the assessment. The session is timetabled for two hours in groups of ten students. The number of students in the group may be increased if more than one spectrometer is available.

A+NaOEtBOOOHOHethyl 6-methylhydroresorcylate

Figure 1. Reaction scheme for the formation of ethyl 6-methylhydroresorcylate. Students are tasked with elucidating the structures of A and B and a mechanism for how they subsequently react with one another to form ethyl 6-methylhydroresorcylate

The experiment is focused on the identification of two unknowns, ethyl crotonate (unknown A) and ethyl acetoacetate (unknown B) respectively; students are told that they react with one another in the presence of sodium ethoxide to produce the product, ethyl 6-methylhydroresorcylate, as shown in Fig. 1. Ethyl 6-methylhydroresorcylate is a precursor in the synthesis of (±)-daurichromenic acid (Fig. 2) which has been shown to have potent anti-HIV activity (EC50 = 0.00567 μg/ml) (Hu et al., 2004). Furthermore, ethyl 6-methylhydroresorcylate is a necessary material in the biosynthesis of PD 116198, a benz[a]anthraquinone antibiotic, produced by Streptomyces phaeochromogenes WP 3688 (Gould & Cheng, 1993). As part of the write up, students are asked to suggest a reaction mechanism for the formation of ethyl 6-methylhydroresorcylate. The mechanism consists of a Michael addition followed by a Claisen condensation, and thus draws upon the knowledge that students will be developing at this stage in their undergraduate course.

OHOOOHMe

Figure 2. Chemical structure of daurichromenic acid: the part of the structure highlighted in blue is derived from ethyl 6-methylhydroresorcylate

Students are provided with CHN elemental microanalysis, IR spectra, mass spectra (electron impact), DEPT and 13C{1H} NMR spectra to help in their elucidation of the two unknown molecules. From the elemental microanalysis data and mass spectra provided, students apprehend that the two compounds only differ by a single oxygen atom (unknown A and B have molecular formulae of C6H10O2 and C6H10O3 respectively). Students should be encouraged to think about functional groups that contain oxygen e.g. ketones, esters, alcohols and use the IR spectra to collaborate or disprove their hypotheses. Key peaks in the IR spectra are detected at 1721.5 cm-1 (C=O) and 1661.9 cm-1 (C=C, alkene) for unknown A and a split peak at 1717.8 cm-1 (two different C=O) for unknown B. As esters easily fragment in the mass spectrometer when electron impact is employed, this is prudent to bring to the student’s attention as well; both unknowns have a weak mass ion in their corresponding mass spectra that reflects this. The appearance of a peak at δ 144.6 in the 13C{1H} NMR for unknown A and at δ 199.7 and 166.4 for unknown B, all of which are not present in the DEPT, reinforce observations in the IR spectra that quaternary, very de-shielded, carbon nuclei are present.

Students are required to collect the 1H NMR spectra and COSY data to complete the necessary characterisation data in order to fully elucidate the structures of unknowns A and B. These data highlight the significant structural differences between the two compounds. A benchtop NMR spectrometer operating at 60 MHz is more than adequate for data collection (an Oxford Instruments’ Pulsar equipped with a 1H / 19F probe was utilised for this work). The facilitator of the session gives students an introduction detailing the purpose of the experiment and an overview of the benchtop NMR device. Safety concerns associated with working in the vicinity of a powerful magnet are also raised e.g. precautions should be taken for students possessing pacemakers or metal-implants. Students were provided with clear user guides for the collection and processing of 1H NMR data. 1) As students will have unrestricted access to the benchtop NMR in the third year of their studies at Manchester Metropolitan University, this provides them with an ample introduction to the instrument and allows them to gain experience using it.

The collection of the 1H-1H COSY (Correlation Spectroscopy) data is run as a group exercise because of the time that is involved in collecting them (~30 min). A building-up approach to 2D NMR spectroscopy using high-field instrumentation has recently been described for second-year undergraduate students with a focus on COSY, HMBC (heteronuclear multiple bond coherence) and HSQC (heteronuclear single quantum coherence) (Anderson-Wile, 2016); crucially this means that the techniques can be revisited in advanced undergraduate courses. Although only COSY is focused on herein, this still provides ample introduction to 2D NMR spectroscopy. Whilst the 1H-1H COSY NMR spectrum is being acquired, students are tasked with sample preparation. The 1H-1H COSY NMR spectrum of ethyl crotonate, unknown A, is shown in Fig. 2; it clearly shows the expected couplings between the CH2 and CH3 of the ethyl group, as well as the couplings between the alkenic protons (a mixture of 3JHH and 4JHH couplings) and the terminal methyl group. The latter couplings are more complex than the former and as such, the 1H-1H COSY NMR spectrum aids the students in elucidating this structural component of the molecule. It can also be useful in deciphering why the complex coupling patterns in the corresponding 1H NMR spectrum arise. Students collect the corresponding 1D 1H NMR spectra for unknowns A or B themselves within their pairs and fully process the data once collected. Spectra were collected using 2 M samples, thus entailing that they are readily collected in one scan and provide adequate signal-to-noise for processing purposes. Data processing can be done on an individual basis, or as seemed commonplace, students would peer support one another through the process using the user guides provided to guide them. Data was processed using the MNOVA software package.

Figure 3. 1H-1H COSY NMR spectrum of ethyl crotonate (compound A) in acetone-D6

The alkenic moiety in ethyl crotonate gives rise to interesting multiplets; even when collected on a 60 MHz instrument, these are sufficiently resolved to deduce the couplings within each multiplet. Coupled with the integral ratios, it is therefore possible for students to not only deduce the chemical environment which gives rise to the signals observed in the 1H NMR spectrum (Fig. 3) but to also deduce the geometrical isomerism of the alkene moiety by deducing the appropriate coupling constants. This is an aspect of the experiment that is pressed upon students; other spectroscopic techniques such as IR and GC-MS will only indicate the presence of an alkene or the molar mass of the material but will not provide information about how other groups attached to it are arranged in space. The alkenic carbon signals are observed at δ 144.6 and 124.0 in the 13C{1H} NMR spectrum and are both positive in the DEPT. Couplings can also be deduced for the methylene and methyl groups of the ethyl group – these show identical coupling constants and thus reinforce the observation of the corresponding cross peak in the1H-1H COSY. They are observed at δ 60.6 and 14.9 in the 13C{1H} NMR spectrum; the latter is positive in the DEPT whereas the former is negative, thus reinforcing its assignment as a methylene carbon.

Figure 4. 1H NMR spectrum of compound A collected in acetone-D6

The 1H NMR spectrum of ethyl acetoacetate, unknown B, possesses enol-keto tautomerism along with the expected peaks. This ties in very well with the enolate chemistry that the students learn during the second year of their studies. When students are collecting this spectrum, it is worth having a demonstrator on hand to point out the presence of additional peaks (marked with an asterisk in Fig. 4) and to facilitate useful discussion regarding the possibilities as to how they may arise (Drexler & Field, 1976). Students find this useful as it helps them to visualise the differences in chemical structure between the enol and keto forms based on the chemical shift data that is contained within the1H NMR.

Figure 5. 1H NMR spectrum of compound B collected in Chloroform-D. Peaks marked with an asterisk belong to the enol form

The four peaks of the predominant keto-form suggest a less coupled structure compared to that of ethyl crotonate. In fact, the 1H-1H COSY spectrum1) only shows that two proton environments couple. The presence of two singlets in the1H NMR spectrum should be impressed upon the students to get them focused on to how this could occur, and what functional groups may lead them to be deshielded to differing extents. Furthermore, the characteristic coupling of an ethyl group is present (peaks at δ 4.21 and 1.29) and these could be used to compare and contrast against those observed in ethyl crotonate. The 13C{1H} NMR signals of the ethyl moiety will also be of use (δ 60.2 and 13.1) as they are very similar to those of unknown A and, therefore, reinforce structural similarity between the two unknowns.

Results

One second year chemistry cohort (n = 98) has completed this assignment. 93% of the students were able to identify molecule A, although only 18% identified it to possess a trans alkene. A further 12% of students identified molecule A to possess a cis alkene with the remainder not identifying the type of geometrical isomerism present. When the geometrical isomerism was incorrectly identified to be cis, this mainly originated due to the students calculating only one coupling constant for the CH group that is α to the methyl group – this possesses both a 6.6 and 15.6 Hz3JHH coupling. The former, when viewed in isolation is suggestive of a cis alkene and, therefore, may have steered the students towards this conclusion. 97% of students were able to correctly identify molecule B.

Compared to the previous assignment, which although identical, was purely paper based and consisted of no experiential learning, this assignment resulted in a ca. 10% increase in the average mark obtained by the students who completed it. Of the seven different sections1) it was the CHN elemental microanalysis section in which students scored the highest (average = 93%). The mass spectrometry, IR spectroscopy, 1H NMR, 13C{1 H} NMR and mechanistic sections averaged 67 – 75%. The lowest scoring section was where the students were asked to deduce the chemical structures and provide rationale for them. The average for this section was 58% - the lower percentile score was mainly due to students providing more of an overview of the data utilised, rather than picking out key data that helped in the elucidation of the structures.

Qualitative data collected from a group of students (n = 10) who helped trial the assignment described herein and who had previously been assessed using the purely paper based assignment stated that “doing a practical as part of the coursework was good and gave me a better understanding” and that it was “a lot more fun to understand a new process”. Having fun and experiencing enjoyment are perceived by adult learners as a motivator to attend classes and learn knowledge and skills (Lucardie, 2014). Students also remarked that the experiment had given them “a wider knowledge of NMR”.

Conclusions

An undergraduate structural elucidation experiment with an emphasis on the collection of 1D and 2D 1H NMR data is detailed. Students obtained hands-on experience of collecting, processing and interpreting NMR data and used it, in conjunction with other analytical data such as IR and MS data, to deduce the chemical structures of two unknowns and the reaction they undergo to produce ethyl 6-methylhydroresorcylate. Students vastly preferred this to a purely paper based exercise, citing that they could take ownership of the data produced and that they could gain valuable experience of NMR spectroscopy if allowed to collect the data themselves. The pedagogic goals, as outlined in the introduction, were achieved as the experiment enabled students to make links between NMR theory and the collection of “real world” data, and for them to utilise 1D and 2D 1H NMR spectroscopy, alongside other analytical methods, to elucidate the structure of organic compounds.

One can envisage that this experiment could be part of a larger laboratory class in which students are split in to teams, for example, and asked to collect all the necessary spectroscopic data to elucidate the structures of the two unknowns. This could be part of a problem-based / enquiry-based learning practical experiment. The experiment could also be further expanded upon by tasking students to synthesise and characterise the product produced (ethyl 6-methylhydroresorcylate) when ethyl crotonate and ethyl acetoacetate react with one another in the presence of base.

Acknowledgments. We acknowledge the second year students at Manchester Metropolitan University for volunteering their time to help test and evaluate this experiment. REM would like to thank Paul Birkett for useful discussions, help in appraising the experiment and for his proactive nature regarding encouraging students to use benchtop NMR. In addition, REM would like to thank Peter Gossman for his help and guidance in conducting the evaluation aspect of this project.

NOTES

1. For the details, contact the corresponding author Dr. R. E. Mewis.

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

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PROBLEM OF THE 8-TH EXPERIMENTAL PHYSICS OLYMPIAD, SKOPJE, 8 MAY 2021 DETERMINATION OF PLANCK CONSTANT BY LED

Todor M. Mishonov, Aleksander P. Petkov, Matteo Andreoni, Emil G. Petkov, Albert M. Varonov, Iglika M. Dimitrova, , Leonora Velkoska, Riste Popeski-Dimovski

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INVESTIGATION OF \(^{238}\)U, \(^{234}\)U AND \(^{210}\)PO 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

COMPARATIVE PERFORMANCE AND DIGESTIBILITY OF NUTRIENTS IN AFSHARI AND GHEZEL RAM LAMBS

Morteza Karami, Fardis Fathizadeh, Arash Yadollahi, Mehran Aboozari, Yaser Rahimian, Reza Alipoor Filabadi

КАЛЦИЙ, ФОСФОР И ДРУГИ ФАКТОРИ ЗА КОСТНО ЗДРАВЕ

Радка Томова, Светла Асенова, Павлина Косева

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THE DAY OF THE INDUCTANCE: PROBLEMS OF THE 7\(^{TH}\) EXPERIMENTAL PHYSICS OLYMPIAD, SKOPJE, 2019

Todor M. Mishonov, Riste Popeski-Dimovski, Leonora Velkoska, Iglika M. Dimitrova, Vassil N. Gourev, Aleksander P. Petkov, Emil G. Petkov, Albert M. Varonov

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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МОЛЕКУЛИТЕ НА УДОВОЛСТВИЕТО

Веселина Янкова, Снежана Демирова, Цветанка Митева, Явор Князов, Христо Желев, Димитър Георгиев, Габриела Стоянова

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

ПРИЛОЖНА ФОТОНИКА И АНТИОКСИДАНТНИ СВОЙСТВА НА ВИСОКООЛЕИНОВО СЛЪНЧОГЛЕДОВО МАСЛО С БИЛКОВИ ПРИМЕСИ

Кръстена Николова, Стефка Минкова, Поли Радушева, Георги Бошев, Еркан Фаридин, Нурал Джамбазов, Мариана Перифанова-Немска

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

2019 − THE INTERNATIONAL YEAR OF THE PERIODIC TABLE OF CHEMICAL ELEMENTS

Maria Atanassova, Radoslav Angelov, Dessislava Gerginova, Alexander Zahariev

ТЕХНОЛОГИЯ

Б. В. Тошев

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ЗЕЛЕНА ХИМИЯ В УЧИЛИЩНАТА ЛАБОРАТОРИЯ

Александрия Генджова, Мая Тавлинова-Кирилова, Александра Камушева

ON THE GENETIC TIES BETWEEN EUROPEAN NATIONS

Jordan Tabov, Nevena Sabeva-Koleva, Georgi Gachev

CAN BRING PEOPLE TOGETHER

Nadya Kantareva-Baruh

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CHEMOMETRIC ANALYSIS OF SCHOOL LIFE IN VARNA

Radka Tomova, Petinka Galcheva, Ivajlo Trajkov, Antoaneta Hineva, Stela Grigorova, Rumyana Slavova, 6Miglena 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

A TALE OF SEVEN SCIENTISTS

Savina Kirilova

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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

ELECTROCHEMICAL IMPEDANCE STUDY OF BSCCO (2212) CUPRATE CERAMIC ADDITIVE TO THE ZINC ELECTRODE IN Ni-Zn BATTERIES

A. Vasev, P. Lilov, G. Ivanova, Y. Marinov, A. Stoyanova, V. Mikli, A. Stoyanova-Ivanova

CALIBRATION OF GC/MS METHOD FOR DETERMINATION OF PHTHALATES

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

SONOCHEMICAL SYNTHESIS OF 4-AMINOANTIPYRINE SCHIFF BASES A ND EVALUATION OF THEIR ANTIMICROBIAL, ANTI-TYROSINASE AND DPPH SCAVENGING ACTIVITIES

Maya Chochkova, Boyka Stoykova, Iva Romanova, Petranka Petrova, Iva Tsvetkova, Hristo Najdenski, Lubomira Nikolaeva- Glomb, Nadya Nikolova, Galya Ivanova, Atanas Chapkanov, Tsenka Milkova, Martin Štícha, Ivan Nemec

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

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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

СРАВНИТЕЛЕН АНАЛИЗ НА СЪДЪРЖАЩИТЕ СЕ ЕСТЕСТВЕНИ РАДИОНУКЛИДИ В НЕВЕН И ЛАЙКА

Сияна Димова, Цветелина Стефанова, Йорданка Енева, Нина Архангелова

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

И. Милкова-Томова, Д. Бухалова, К. Николова, И. 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

ЕКСПЕРИМЕНТЪТ ПО ПРИЛОЖНА ФИЗИКА И НЕГОВАТА РОЛЯ ПРИ УСВОЯВАНЕТО НА ПРАКТИКО-ПРИЛОЖНИТЕ ЗНАНИЯ ОТ КУРСАНТИТЕ И СТУДЕНТИТЕ

Николай Тодоров Долчинков, Бонка Енчева Караиванова-Долчинкова, Nikolay Dolchinkov, Bonka Karaivanova-Dolchinkova

ЕЛЕКТРИЧНИ СВОЙСТВА НА КОМПОЗИТНИ ФИЛМИ ОТ ПОЛИМЛЕЧНА КИСЕЛИНА

Ася Виранева, Иван Бодуров, Теменужка Йовчева

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PHYSICS IS AN EVER YOUNG SCIENCE

Temenuzhka Yovcheva

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

ТЪМНАТА МАТЕРИЯ В КЛАСНАТА СТАЯ

Симона Стоянова, Анета 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

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

Veselina Kolarski, Dancho Danalev, Senia Terzieva

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ZAGREB CONNECTION INDICES OF \(\mathrm{TiO}_{2}\) 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

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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

SYNTHESIS OF TiO 2-M (Cd, Co, Mn) AS A PHOTOCATALYST DEGRADATION OF METHYLENE BLUE DYE

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 <i>IN VITRO</i> ANTIOXIDANT STUDIES OF <i>PRIMULA VERIS</i> (L.) GROWING WILD IN KOSOVO

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

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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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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

CHEMOMETRICASSISTEDSPECTROPHOTOMETRIC ESTIMATION OF LANSOPRAZOLE AND DOMEPERIDONE IN BULK AND COMMERCIAL DOSAGE FORM

Farheen Sami, Shahnaz Majeed, Tengku Azlan Shah Tengku Mohammed, Noor Fatin Amalina Kamaruddin, Mohammad Zulhimi Atan, Syed Amir Javid Bukhari, Namra, Bushra Hasan, Mohammed Tahir Ansari

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

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

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ПРИРОДОНАУЧНАТА ГРАМОТНОСТ НА УЧЕНИЦИТЕ В НАЧАЛОТО НА XXI ВЕК – В ТЪРСЕНЕ НА КОНЦЕПТУАЛНО ЕДИНСТВО

Теодора Коларова, Иса Хаджиали, Мимия Докова, Веселин Александров

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

Arsim Maloku, Liridon S. Berisha, Granit Jashari, Eduard Andoni, Tahir Arbneshi

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

Надежда Райчева, Иса Хаджиали, Наташа Цанова, Виктория Нечева

EXISTING NATURE OF SCIENCE TEACHING OF A THAI IN-SERVICE BIOLOGY TEACHER

Wimol Sumranwanich, Sitthipon Art-in, Panee Maneechom, Chokchai Yuenyong

NUTRIENT COMPOSITION OF CUCURBITA MELO GROWING IN KOSOVO

Fatmir Faiku, Arben Haziri, Fatbardh Gashi, Naser Troni

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CONTEXT-BASED CHEMISTRY LAB WORK WITH THE USE OF COMPUTER-ASSISTED LEARNING SYSTEM

N. Y. Stozhko, A. V. Tchernysheva, E.M. Podshivalova, B.I. Bortnik

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ПО ПЪТЯ ON THE ROAD

Б. В. Тошев

INTERDISCIPLINARY PROJECT FOR ENHANCING STUDENTS’ INTEREST IN CHEMISTRY

Stela Georgieva, Petar Todorov, Zlatina Genova, Petia Peneva

2015 година
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COMPLEX SYSTEMS FOR DRUG TRANSPORT ACROSS CELL MEMBRANES

Nikoleta Ivanova, Yana Tsoneva, Nina Ilkova, Anela Ivanova

SURFACE FUNCTIONALIZATION OF SILICA SOL-GEL MICROPARTICLES WITH EUROPIUM COMPLEXES

Nina Danchova, Gulay Ahmed, Michael Bredol, Stoyan Gutzov

INTERFACIAL REORGANIZATION OF MOLECULAR ASSEMBLIES USED AS DRUG DELIVERY SYSTEMS

I. Panaiotov, Tz. Ivanova, K. Balashev, N. Grozev, I. Minkov, K. Mircheva

KINETICS OF THE OSMOTIC PROCESS AND THE POLARIZATION EFFECT

Boryan P. Radoev, Ivan L. Minkov, Emil D. Manev

WETTING BEHAVIOR OF A NATURAL AND A SYNTHETIC THERAPEUTIC PULMONARY SURFACTANTS

Lidia Alexandrova, Michail Nedyalkov, Dimo Platikanov

Книжка 5
TEACHER’S ACCEPTANCE OF STUDENTS WITH DISABILITY

Daniela Dimitrova-Radojchikj, Natasha Chichevska-Jovanova

APPLICATION OF LASER INDUCED BREAKDOWN SPECTROSCOPY AS NONDESDUCTRIVE AND SAFE ANALYSIS METHOD FOR COMPOSITE SOLID PROPELLANTS

Amir Hossein Farhadian, Masoud Kavosh Tehrani, Mohammad Hossein Keshavarz, Seyyed Mohamad Reza Darbany, Mehran Karimi, Amir Hossein Rezayi

THE EFFECT OF DIOCTYLPHTHALATE ON INITIAL PROPERTIES AND FIELD PERFORMANCE OF SOME SEMISYNTHETIC ENGINE OILS

Azadeh Ghasemizadeh, Abolfazl Semnani, Hamid Shakoori Langeroodi, Alireza Nezamzade Ejhieh

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Fatmir Faiku, Arben Haziri, Fatbardh Gashi, Naser Troni

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БЛАГОДАРЯ ВИ!

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ТЕМАТА ВЪГЛЕХИДРАТИ В ПРОГРАМИТЕ ПО ХИМИЯ И БИОЛОГИЯ

Радка Томова, Елена Бояджиева, Миглена Славова, Мариан Николов

BILINGUAL COURSE IN BIOTECHNOLOGY: INTERDISCIPLINARY MODEL1)

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ХИМИЧНИЯТ ОПИТ – НАУКА И ЗАБАВА

Елица Чорбаджийска, Величка Димитрова, Магдалена Шекерлийска, Галина Бальова, Методийка Ангелова

ЕКОЛОГИЯТА В БЪЛГАРИЯ

Здравка Костова

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

Boyka Stoykova, Maya Chochkova, Galya Ivanova, Luchia Mukova, Nadya Nikolova, Lubomira Nikolaeva-Glomb, Pavel Vojtíšek, Tsenka Milkova, Martin Štícha, David Havlíček

SYNTHESIS AND ANTIVIRAL ACTIVITY OF SOME AMINO ACIDS DERIVATIVES OF INFLUENZA VIRUS DRUGS

Radoslav Chayrov, Vesela Veselinova, Vasilka Markova, Luchia Mukova, Angel Galabov, Ivanka Stankova

NEW DERIVATIVES OF OSELTAMIVIR WITH BILE ACIDS

Kiril Chuchkov, Silvia Nakova, Lucia Mukova, Angel Galabov, Ivanka Stankova

MONOHYDROXY FLAVONES. PART III: THE MULLIKEN ANALYSIS

Maria Vakarelska-Popovska, Zhivko Velkov

LEU-ARG ANALOGUES: SYNTHESIS, IR CHARACTERIZATION AND DOCKING STUDIES

Tatyana Dzimbova, Atanas Chapkanov, Tamara Pajpanova

LACTOBACILLUS PLANTARUM AC 11S AS A BIOCATALYST IN MICROBIAL ELECYTOLYSIS CELL

Elitsa Chorbadzhiyska, Yolina Hubenova, Sophia Yankova, Dragomir Yankov, Mario Mitov

STUDYING THE PROCESS OF DEPOSITION OF ANTIMONY WITH CALCIUM CARBONATE

K. B. Omarov, Z. B. Absat, S. K. Aldabergenova, A. B. Siyazova, N. J. Rakhimzhanova, Z. B. Sagindykova

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TEACHING CHEMISTRY AT TECHNICAL UNIVERSITY

Lilyana Nacheva-Skopalik, Milena Koleva

ФОРМИРАЩО ОЦЕНЯВАНЕ PEER INSTRUCTION С ПОМОЩТА НА PLICКERS ТЕХНОЛОГИЯТА

Ивелина Коцева, Мая Гайдарова, Галина Ненчева

VAPOR PRESSURES OF 1-BUTANOL OVER WIDE RANGE OF THEMPERATURES

Javid Safarov, Bahruz Ahmadov, Saleh Mirzayev, Astan Shahverdiyev, Egon Hassel

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РУМЕН ЛЮБОМИРОВ ДОЙЧЕВ (1938 – 1999)

Огнян Димитров, Здравка Костова

NAMING OF CHEMICAL ELEMENTS

Maria Atanassova

2014 година
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LUBRICATION PROPERTIES OF DIFFERENT PENTAERYTHRITOL-OLEIC ACID REACTION PRODUCTS

Abolfazl Semnani, Hamid Shakoori Langeroodi, Mahboube Shirani

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

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GENDER ISSUES OF UKRAINIAN HIGHER EDUCATION

Н.H.Petruchenia, M.I.Vorovka

МНОГОВАРИАЦИОННА СТАТИСТИЧЕСКА ОЦЕНКА НА DREEM – БЪЛГАРИЯ: ВЪЗПРИЕМАНЕ НА ОБРАЗОВАТЕЛНАТА СРЕДА ОТ СТУДЕНТИТЕ В МЕДИЦИНСКИЯ УНИВЕРСИТЕТ – СОФИЯ

Радка Томова, Павлина Гатева, Радка Хаджиолова, Зафер Сабит, Миглена Славова, Гергана Чергарова, Васил Симеонов

MUSSEL BIOADHESIVES: A TOP LESSON FROM NATURE

Saâd Moulay Université Saâd Dahlab de Blida, Algeria

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ЕЛЕКТРОННО ПОМАГАЛO „ОТ АТОМА ДО КОСМОСА“ ЗА УЧЕНИЦИ ОТ Х КЛАС

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44<sup>-ТA</sup> МЕЖДУНАРОДНА ОЛИМПИАДА ПО ХИМИЯ

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COMPUTER ASSISTED LEARNING SYSTEM FOR STUDYING ANALYTICAL CHEMISTRY

N. Y. Stozhko, A. V. Tchernysheva, L.I. Mironova

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ВИСША МАТЕМАТИКА ЗА УЧИТЕЛИ, УЧЕНИЦИ И СТУДЕНТИ: ДИФЕРЕНЦИАЛНО СМЯТАНЕ

Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

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Б. В. Тошев Българско дружество за химическо образование и история и философия на химията

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BOTYU ATANASSOV BOTEV

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CHRONOLOGY OF CHEMICAL ELEMENTS DISCOVERIES

Maria Atanassova, Radoslav Angelov

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КАК ДА МОТИВИРАМЕ УЧЕНИЦИТЕ OT VII КЛАС ДА УЧАТ

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ОБРАЗОВАНИЕ ЗА ПРИРОДОНАУЧНА ГРАМОТНОСТ

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DIFFERENTIAL TEACHING IN SCHOOL SCIENCE EDUCATION: CONCEPTUAL PRINCIPLES

G. Yuzbasheva Kherson Academy of Continuing Education, Ukraine

АНАЛИЗ НА ПОСТИЖЕНИЯТА НА УЧЕНИЦИТЕ ОТ ШЕСТИ КЛАС ВЪРХУ РАЗДЕЛ „ВЕЩЕСТВА И ТЕХНИТЕ СВОЙСТВА“ ПО „ЧОВЕКЪТ И ПРИРОДАТА“

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„Образователни стандарти и природонаучна грамотност“ – това е темата на състоялата се от 25 до 27 октомври 2013 г. в Габрово 45. Национална конфе- ренция на учителите по химия с международно участие, която по традиция се проведе комбинирано с Годишната конференция на Българското дружество за химическо образование и история и философия на химията. Изборът на темата е предизвикан от факта, че развиването на природонаучна грамотност е обща тенденция на реформите на учебните програми и главна

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ЗА ХИМИЯТА НА БИРАТА

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

Srihari Murthy Meenakshi Sundararajan Engineering College, India

CHEMICAL REACTIONS DO NOT ALWAYS MODERATE CHANGES IN CONCENTRATION OF AN ACTIVE COMPONENT

Joan J. Solaz-Portolés, Vicent Sanjosé Universitat de Valènciа, Spain

POLYMETALLIC COMPEXES: CV. SYNTHESIS, SPECTRAL, THERMOGRAVIMETRIC, XRD, MOLECULAR MODELLING AND POTENTIAL ANTIBACTERIAL PROPERTIES OF TETRAMERIC COMPLEXES OF Co(II), Ni(II), Cu(II), Zn(II), Cd(II) AND Hg(II) WITH OCTADENTATE AZODYE LIGANDS

Bipin B. Mahapatra, S. N. Dehury, A. K. Sarangi, S. N. Chaulia G. M. Autonomous College, India Covt. College of Engineering Kalahandi, India DAV Junior College, India

ПРОФЕСОР ЕЛЕНА КИРКОВА НАВЪРШИ 90 ГОДИНИ

CELEBRATING 90TH ANNIVERSARY OF PROFESSOR ELENA KIRKOVA

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SIMULATION OF THE FATTY ACID SYNTHASE COMPLEX MECHANISM OF ACTION

M.E.A. Mohammed, Ali Abeer, Fatima Elsamani, O.M. Elsheikh, Abdulrizak Hodow, O. Khamis Haji

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G. Yuzbasheva Kherson Academy of Continuing Education, Ukraine

ИЗСЛЕДВАНЕ НА РАДИКАЛ-УЛАВЯЩА СПОСОБНОСТ

Станислав Станимиров, Живко Велков

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COLORFUL EXPERIMENTS FOR STUDENTS: SYNTHESIS OF INDIGO AND DERIVATIVES

Vanessa BIANDA, Jos-Antonio CONSTENLA, Rolf HAUBRICHS, Pierre-Lonard ZAFFALON

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Mila Ivanova Luleva, Harald van der Werff, Freek van der Meer, Victor Jetten

ЦАРСКАТА ПЕЩЕРА

Рафаил ПОПОВ

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Учебни лаборатории Илюстрации от каталог на Franz Hugershoff, Лайциг, притежаван от бъдещия

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ADDRESING STUDENTS’ MISCONCEPTIONS CONCERNING CHEMICAL REACTIONS AND SYMBOLIC REPRESENTATIONS

Marina I. Stojanovska, Vladimir M. Petruševski, Bojan T. Šoptrajanov

АНАЛИЗ НА ПОСТИЖЕНИЯТА НА УЧЕНИЦИТЕ ОТ ПЕТИ КЛАС ВЪРХУ РАЗДЕЛ „ВЕЩЕСТВА И ТЕХНИТЕ СВОЙСТВА“ ПО ЧОВЕКЪТ И ПРИРОДАТА

Иваничка Буровска, Стефан Цаковски Регионален инспекторат по образованието – Ловеч

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Васил Симеонов

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

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Sunanda S. Aswale, Shashikant R. Aswale, Aparna B. Dhote Lokmanya Tilak Mahavidyalaya, INDIA Nilkanthrao Shinde College, INDIA

SIMULTANEOUS ESTIMATION OF IBUPROFEN AND RANITIDINE HYDROCHLORIDE USING UV SPECTROPHOT O METRIC METHOD

Jadupati Malakar, Amit Kumar Nayak Bengal College of Pharmaceutical Sciences and Research, INDIA

GAPS AND OPPORTUNITIES IN THE USE OF REMOTE SENSING FOR SOIL EROSION ASSESSMENT

Mila Ivanova Luleva, Harald van der Werff, Freek van der Meer, Victor Jetten

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TEACHING THE CONSTITUTION OF MATTER

Małgorzata Nodzyńska, Jan Rajmund Paśko

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Маша Радославова, Ася Драгоева

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Чл. 1. Съставянето и издаване на учебници се предоставя на частната инициа- тива. Забележка: На учителите – съставители на учебници се запрещава сами да разпродават своите учебници. Чл. 2. Министерството на народното просвещение може да определя премии по конкурс за съставяне на учебници за горните класове на гимназиите и специ- алните училища. Чл. 3. Никой учебник не може да бъде въведен в училищата, ако предварително не е прегледан и одобрен от Министерството на народното просвещение. Чл.

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John Dewey (1859 – 1952)

ИНФОРМАЦИЯ ЗА СПЕЦИАЛНОСТИТЕ В ОБЛАСТТА НА ПРИРОДНИТЕ НАУКИ В СОФИЙСКИЯ УНИВЕРСИТЕТ „СВ. КЛИМЕНТ ОХРИДСКИ“ БИОЛОГИЧЕСКИ ФАКУЛТЕТ

1. Биология Студентите от специалност Биология придобиват знания и практически умения в областта на биологическите науки, като акцентът е поставен на организмово равнище. Те се подготвят да изследват биологията на организмите на клетъчно- организмово, популационно и екосистемно ниво в научно-функционален и прило- жен аспект, с оглед на провеждане на научно-изследователска, научно-приложна, производствена и педагогическа дейност. Чрез широк набор избираеми и факул- тативни курсове студентите

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УЧИТЕЛИТЕ ПО ПРИРОДНИ НАУКИ – ЗА КОНСТРУКТИВИСТКАТА УЧЕБНА СРЕДА В БЪЛГАРСКОТО УЧИЛИЩЕ

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Бурният развой на естествознанието във всичките му клонове през XIX –ия век предизвика дълбоки промени в мирогледа на културния свят, в техниката и в индустрията, в социалните отношения и в държавните интереси. Можем ли днес да си представим един философ, един държавен мъж, един обществен деец, един индустриалец, просто един културен човек, който би могъл да игнорира придобив- ките на природните науки през последния век. Какви ужасни катастрофи, какви социални сътресения би сполетяло съвре

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MURPHY’S LAW IN CHEMISTRY

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Семейството трябва да познава училишето и училишето трябва да познава семейството. Взаимното познанство се налага от обстоятелството, че те, макар и да са два различни по природата си фактори на възпитанието, преследват една и съща проста цел – младото поколение да бъде по-умно, по-нравствено, физически по-здраво и по-щастливо от старото – децата да бъдат по-щастливи от родителите