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1

Electron Dynamics in Crystalline Semiconductors

100%

Zawadzki W.

Acta Physica Polonica A

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2013

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vol. 123

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issue 1

132-138

EN

Electron dynamics in crystalline semiconductors is described by distinguishing between an instantaneous velocity related to electron's momentum and an average velocity related to its quasi-momentum in a periodic potential. It is shown that the electron velocity used in the theory of electron transport and free-carrier optics is the average electron velocity, not the instantaneous velocity. An effective mass of charge carriers in solids is considered and it is demonstrated that, in contrast to the "acceleration" mass introduced in textbooks, it is a "velocity" mass relating carrier velocity to its quasi-momentum that is a much more useful physical quantity. Among other advantages, the velocity mass is a scalar for spherical but nonparabolic energy bands ϵ(k), whereas the acceleration mass is not a scalar. Important applications of the velocity mass are indicated. A two-band k·p^ model is introduced as the simplest example of a band structure that still keeps track of the periodic lattice potential. It is remarked that the two-band model, adequately describing narrow-gap semiconductors (including zero-gap graphene), strongly resembles the special theory of relativity. Instructive examples of the "semi-relativistic" analogy are given. The presentation has both scientific and pedagogical aspects.

2

Density of States for Ballistic Electrons in Electric and Magnetic Fields

64%

Zawadzki W., Kubisa M.

Acta Physica Polonica A

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1999

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vol. 96

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issue 5

603-612

EN

The density of states for ballistic electrons in the presence of an electric field of almost arbitrary shape is calculated for one, two, and three dimensions using the semiclassical quantization in a finite sample. The semiclassical results are compared with these of the complete quantum treatment for a constant electric field. The case of crossed electric and magnetic fields is also considered and it is demonstrated that in this configuration the density of states exhibits a transition between magnetic and electric types of motion. Implications of this transition for the quantum Hall effect are mentioned.

3

Oblique Reflection of Electrons from a Potential Barrier in Heterostructures

64%

Pfeffer P., Zawadzki W.

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2014

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vol. 126

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issue 3

820-827

EN

Reflection of electrons from a potential barrier in heterostructures is described. An electric field of the barrier causes spin splitting of electron energies via the spin-orbit interaction and its form is calculated in the three-level k·p model for a nontrivial case of unbound electrons. It is shown that if the potential barrier is the only source of the spin-orbit interaction, the spin-flip electron reflections are not possible. However, there appear two unexpected possibilities related to the spin-orbit interaction: (a) non-attenuated electron propagation in the barrier whose height exceeds the energies of incoming electrons, (b) total reflection of electrons whose energies exceed barrier's height. It is indicated that the system can serve as a source of spin-polarized electron beams.

4

In vitro study of the effect of corn dried distillers grains with solubles on rumen fermentation in sheep

39%

Pecka-Kiełb E., Zawadzki W., Zachwieja A., Michel O., Mazur M., Miśta D.

Polish Journal of Veterinary Sciences

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2015

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issue 4

5

The effect of humic-fatty acid preparation on selected haematological and biochemical serum parameters of growing rabbits

39%

Miśta D., Rząsa A., Wincewicz E., Zawadzki W., Dobrzański Z., Szmańko T., Gelles A.

Polish Journal of Veterinary Sciences

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2012

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issue 2

6

An effect of mammary gland infection caused by Streptococcus uberis on composition and physicochemical changes of cows’ milk

33%

Pecka-Kiełb E., Vasil M., Farkasóvá Z., Zachwieja A., Zawadzki W., Elečko J., Zigo F., Illek J.

Polish Journal of Veterinary Sciences

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2016

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issue 1

7

Effects of udder infections with Staphylococcus xylosus and Staphylococcus warneri on the composition and physicochemical changes in cows milk

33%

Pecka-Kiełb E., Vasil M., Farkasóvá Z., Elečko J., Zachwieja A., Zawadzki W., Zigo F., Illek J.

Polish Journal of Veterinary Sciences

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2016

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issue 4

8

The effect of Linola and W92/72 transgenic flax seeds on the rabbit caecal fermentation - in vitro study

33%

Miśta D., Króliczewska B., Zawadzki W., Pecka E., Steininger M., Hull S., Żuk M., Szopa J.

Polish Journal of Veterinary Sciences

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2011

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issue 4

Refine search results

Electron Dynamics in Crystalline Semiconductors

Density of States for Ballistic Electrons in Electric and Magnetic Fields

Oblique Reflection of Electrons from a Potential Barrier in Heterostructures

In vitro study of the effect of corn dried distillers grains with solubles on rumen fermentation in sheep

The effect of humic-fatty acid preparation on selected haematological and biochemical serum parameters of growing rabbits

An effect of mammary gland infection caused by Streptococcus uberis on composition and physicochemical changes of cows’ milk

Effects of udder infections with Staphylococcus xylosus and Staphylococcus warneri on the composition and physicochemical changes in cows milk

The effect of Linola and W92/72 transgenic flax seeds on the rabbit caecal fermentation - in vitro study