Khimiya, Volume 15, Issue 4 (2006)
Khimiya. 15, 243-255 (2006):
Abstract.
The home chemical experiments
are not widely used in teaching practice in chemistry. However these experiments seem to
be an effective tool for enhancing the interest of pupils to chemistry. The study involved
137 7th-grade students from local schools in Sofia and Kazanlak. These students
had copleted a carefully chosen set of home experiments. Then their interviews were
recorded, transcribed, and analysed for further understandings of the appropriateness of
the method applied. The tutors of the students had been trained before instruction to be
sure they understood the task to fulfil the goals of the experiments. As a matter of fact
this paper describes a special case study. By realizing our home-experiment-strategy we
now believe that the pupils, even at the early stage of their chemistry learning, have
understood that i) chemistry requires experiments; ii) students must learn and practice (a
form of ) scientific method; iii) essential factors in a positive learning environment
include discipline and good order. The conclusions for the teachers must be: i) the
learning environment is critical to a positive, productive learning effort; ii) the
teacher must be a motivator; iii) the students need a challenge; iv) a real-world
applicability is part of understanding the importance of chemistry.
Keywords: interest of pupils to chemistry; home chemical
experiment
References: 22
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Khimiya. 15, 256-264 (2006):
Abstract. Chemical equilibrium is
characteristic in all cases where the direct and the reverse reaction occur
simultaneously. The equilibrium reagent composition can be altered by changing the
pressure, the temperature or the concentration of some participants in the reaction. In
this paper a lecture demonstration is offered showing the temperature dependent
equilibrium between NO2 and N2O4. It may also serve as an
example of continuous thermochromism, owing to the fact that NO2 is coloured,
while N2O4 is not. The demonstration is performed in a purpose
designed sealed vessel, thus making it both safe and cheap (it may be repeated indefinite
number of times with the same equipment).The RGB
color arguments of fixed region in a series of photographs were measured as a function of
temperature. An absorption function A, was
introduced on the basis of the color arguments, its value being proportional to the NO2
concentration. Finally, a best-fit function was fitted to the pairs of data
absorption–temperature using non-linear least squares interpolation.
Keywords: chemical equilibrium, temperature
dependence, nitrogen dioxide, dinitrogen tetraoxide, lecture demonstration.
References: 14
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Khimiya. 15, 265-274 (2006):
References: 5
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Khimiya, 15, 275-304 (2006):
Abstract. This review is primarily intended to
attract the attention of amateurs into the field of lectins, an interdisciplinary science
that promises its future impact in disease diagnosis and therapy, by providing simple and
yet informative features of lectins highlighting chemical, structural and biological
aspects including its applications in drug targeting and use of lectin-gold complexes in
diagnosis.
Keywords:
Legume lectins; Agglutination of cells; Carbohydrate recognition domain (CRD); Lectin – carbohydrate interaction; Metal ion
binding core; Concanavalin A (Con A); Isothermal titration calorimetry (ITC); Surface
plasmon resonance imaging (SPR); Atomic force microscopy (AFM); Differential scanning
calorimetry (DSC); Lectin – gold complexes; Lectin-mediated drug delivery; Anti-adhesion
therapy.
References: 12
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Khimiya,
15, 305-310 (2006):
Abstract. Classical thermodynamics, based on
conservation of matter and energy and on the increase of entropy accompanying every
natural event, reliably predicts equilibrium properties of macroscopic systems, regardless
of the complexity of those systems. Thermodynamic theory historically has had little to
say about the far-from-equilibrium evolution of systems. This is in part because the
classical laws of thermodynamics, limited to requirements about the degree and direction
of change, are silent about the means and pathways for achieving change. We propose a
simply stated yet powerful Fourth Law of Thermodynamics that significantly extends the
domain of thermodynamics by incorporating evolving systems and thereby adding richness to
thermodynamic description.
Keywords: classical thermodynamics;
far-from-equilibrium systems; fourth law of thermodynamics
References: 11
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Khimiya, 15, 311-328 (2006)
Abstract. This paper presents some findings of a
documentary research on the life story and scientific career development of the Bulgarian
physical chemist Iwan N. Stranski (1897-1979), who is internationally acknowledged for being ‘The
Father of Crystal Growth’. The research has
been carried out at 18 Archive Institutes – 3 in Bulgaria and 15 – abroad (in Germany,
USA and United Kingdom). The collected archive documents provide a good basis for writing
I. Stranski’s biography (Up to date there is no any written biography of
I. Stranski, neither in German nor in Bulgarian, despite the fact that over the course of
time at least 10 official celebrations of Stranski’s
jubilees took place in Western Berlin.) The fieldwork on this project carried out in Germany
became possible due to the offered visiting study fellowship from DAAD in 2002.
Keywords: I.N. Stranski
(1897-1979), archives fieldwork
References:
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