Geodetic and seismological observations applied for investigation of subsidence formation in the CSM Mine (Czech Republic)

Purpose. Undermined areas are affected by the creation of subsidence depressions due to long-term underground mining. In general, different geodetic methods are applied to obtain further information needed to determine the spatial development of the formation of a subsidence depression. Methods. Application of these surveying methods enables us to investigate spatio-temporal changes of landscape relief in detail. Although the development of surveying technologies is in progress at present, conventional geodetic methods are still in use. Nowadays Global Navigation Satellite System (GNSS) surveying is mostly used for obtaining the actual degree of relief affection in undermined areas. Considering that during coal extraction induced seismic events are observed underground and on the surface, some seismological methods for their parameters determination were applied, e.g. foci location of induced seismic events, their classification by units of magnitude and by released seismic energy, frequency energy distribution, construction of Benioff graph and its derivation for assessment of adjacent working endangerment. Findings. The results of the assessment and analyses of spatial data demonstrate the real development of the sub-sidence depression under study and the relief changes of the landscape during the investigated period, respectively. Originality. It was recognized that all methods applied in this study represent very helpful tools for surveying subsidence depression and simultaneous monitoring of seismic activity development on an undermined area. Practical implications. Based on obtained results it is possible to perform a comparison of current subsidence dimensions with the original rate of affection.Мета. Дослідження причин утворення просідань земної поверхні в околиці шахти CSM (Чеська Республіка) за допомогою геодезичних і сейсмологічних методів спостереження. Методика. В роботі використано сейсмічні методи для визначення локалізації місць явищ техногенної сейсмічності, їх класифікації за магнітудами і кількістю виділеної сейсмічної енергії та її частотного розподілу; побудову графіка Беньофа та його модифікацію для оцінки безпеки суміжних до шахти територій; моделювання просторово-часового розвитку опускання поверхні за допомогою GPS-вимірювань. Результати. У результаті оцінки та аналізу просторових даних була визначена реальна область просідань і зміни навколишнього рельєфу протягом всього часу проведення досліджень. Ґрунтуючись на аналізі наявних сейсмічних даних та наземних GPS-вимірювань, встановлено, що протягом досліджуваного періоду ніякого виразного впливу розвитку зсувів і деформацій поверхні через сейсмічну активність не спостерігалося. Виконано моделювання просторово-часового розвитку опускання поверхні у досліджуваній області, що дозволило визначити швидкість осідання поверхні з часом. Визначено горизонтальні переміщення окремих точок і встановлено, що великі тектонічні розломи створюють природний бар’єр зсувам у масиві. Наукова новизна. Використання унікального комплексу методів дослідження та моніторингу, застосовані у даній роботі, дозволили точно виявити область просідання поверхні й причини її утворення, а також здійснити моніторинг сейсмічної активності в районі, порушеному гірничими роботами. Практична значимість. Отримані результати дозволяють порівняти сучасний стан утворених просідань з їх початковими параметрами, а також прогнозувати інтенсивність їх розвитку у часі.Цель. Исследование причин образования проседания земной поверхности в окрестности шахты CSM (Чешская Республика) при помощи геодезических и сейсмологических методов наблюдения. Методика. В работе использовано сейсмические методы для определения локализации очагов явлений техногенной сейсмичности, их классификации по магнитудам и количеству выделенной сейсмической энергии и ее частотного распределения; построение графика Беньофа и его модификацию для оценки безопасности прилегающих к шахте территорий; моделирование пространственно-временного развития опускания поверхности при помощи GPS-измерений. Результаты. В результате оценки и анализа пространственных данных была определена реальная область проседаний и изменения окружающего рельефа в течение всего времени проведения исследований. Основываясь на анализе имеющихся сейсмических данных и наземных GPS-измерений, установлено, что в течение исследуемого периода никакого выразительного влияния развития смещений и деформаций поверхности из-за сейсмической активности не наблюдалось. Выполнено моделирование пространственно-временного развития опускания поверхности в исследуемой области, позволившее определить скорость оседания поверхности с течением времени. Определены горизонтальные перемещения отдельных точек и установлено, что крупные тектонические разломы создают естественный барьер смещениям в массиве. Научная новизна. Использование уникального комплекса методов исследования и мониторинга, примененные в данной работе, позволили точно выявить область проседания поверхности и причины ее образования, а также осуществить мониторинг сейсмической активности в районе, затронутом горными работами. Практическая значимость. Полученные результаты позволяют сравнить современное состояние образовавшейся впадины с ее первоначальными параметрами, а также прогнозировать интенсивность ее развития со временем.This article was written in connection with the Project Institute of Clean Technologies for Mining and Utilization of Raw Materials for Energy Use – Sustainability Program (reg. No.CZ.1.05/2.1.00/03.0082 and MSMT LO1406), which is supported by the Research and Development for Innovations Operational Programme financed by the Structural Funds of the European Union and the Czech Republic project for the longterm conceptual development of research organisations (RVO: 68145535). Many thanks to Dr. Karel Holub, emeritus researcher from the Institute of Geonics of the Czech Academy of Sciences, for his helpful comments and advices during preparation of manuscript. R.I.P

Polymers with different azobenzene moiety for NLO application

Date du colloque&nbsp;: 06/2010</p

Temperature Dependence of the Bistable Photoconductivity of Thin DNA: PEDOT Films

Thin DNA: PEDT-PSS layers were investigated. The functionalization of DNA by PEDT-PSS rendered the material electrically active, its conductivity being about (1-5) x 10(-10) Omega(-1)cm(-1) at the room temperature. The samples remained ohmic down to 77 K. The thermal activation energy of the conductivity near the room temperature was about 0.033 eV, and it decreased under 0.014 eV below 170-180 K. The weak carrier trapping was identified by the Thermally Stimulated Current method, proving the recombination of light-generated carriers. Notably, by constant light excitation a "bistable" photoconduction below the room temperature was evidenced. The photosensitive state could be induced by the light from the spectral region from similar to 500 nm up to similar to 1000 nm, with a maximum effect in the range of 650-800 nm. A remarkable increase of the photocurrent could be observed below 145-155 K by cooling the samples. Meanwhile by heating the photosensitivity remained increased up to 235-245 K. The long characteristic relaxation times after the light excitation in this state were proportional to the relative photosensitivity of material. This indicates that such phenomenon could presumably be attributed to the light-induced changes associated with PEDT-PSS, i.e., modification of the sample material morphology and/or induced variation of carrier transport conditions

Lattice Distortion and Magnetism of 3d-t2gt_{2g} Perovskite Oxides

Several puzzling aspects of interplay of the experimental lattice distortion and the the magnetic properties of four narrow $t_{2g}$-band perovskite oxides (YTiO$_3$, LaTiO$_3$, YVO$_3$, and LaVO$_3$) are clarified using results of first-principles electronic structure calculations. First, we derive parameters of the effective Hubbard-type Hamiltonian for the isolated $t_{2g}$ bands using newly developed downfolding method for the kinetic-energy part and a hybrid approach, based on the combination of the random-phase approximation and the constraint local-density approximation, for the screened Coulomb interaction part. Then, we solve the obtained Hamiltonian using a number of techniques, including the mean-field Hartree-Fock (HF) approximation, the second-order perturbation theory for the correlation energy, and a variational superexchange theory. Even though the crystal-field splitting is not particularly large to quench the orbital degrees of freedom, the crystal distortion imposes a severe constraint on the form of the possible orbital states, which favor the formation of the experimentally observed magnetic structures in YTiO$_3$, YVO_, and LaVO$_3$ even at the HF level. Beyond the HF approximation, the correlations effects systematically improve the agreement with the experimental data. Using the same type of approximations we could not reproduce the correct magnetic ground state of LaTiO$_3$. However, we expect that the situation may change by systematically improving the level of approximations for dealing with the correlation effects.Comment: 30 pages, 17 figures, 8 tables, high-quality figures are available via e-mai

Investigation of functionalised thin films of DNA:PEDT-PSS - electrical and optical properties

We have investigated electrical, charge transport and optical properties of functionalised DNA:PEDT-PSS thin films. Current-voltage dependencies of the samples were linear and symmetrical down to 77 K temperature. Material conductivity at room temperature was about (1-5)Ã10-10 ¿-1 cm-1. The thermal activation energy of the conductivity measured in the dark was about 0.033 eV near the room temperature independently on the applied bias. The weakly expressed carrier trapping was identified by the thermally stimulated current method, evidencing the fast recombination of light-generated carriers. Though, at constant light excitation a "bistable" photoconduction below the room temperature was identified. I.e., upon excitation by light from the spectral region 500 800 nm a notable increase of the photocurrent could be observed below 140 160 K by cooling the samples. Meanwhile by heating the photosensitivity remained increased up to 230 240 K. Most probably such phenomenon could be attributed to the light-induced morphology changes of the samples

Analysis of Electrical and Optical Properties of DNA:PDT-PSS Thin Films

We report investigations of functionalized DNA:PEDT-PSS films. The electrical conductivity of the sample material at the room temperature was about (1–5)*10-10 Ω-1cm-1. The IV curves of the samples were linear and symmetrical in the region from the room temperature down to the liquid Nitrogen temperature. The thermal activation energy of the conductivity near the room temperature was about 0.033 eV independently on the applied bias. The weak carrier trapping was identified by the Thermally Stimulated Current method, proving the fast recombination of light-generated carriers. Notably, by constant light excitation a “bistable” photoconduction below the room temperature was evidenced. I.e., upon excitation by a white light a remarkable increase of the photocurrent could be observed below 145–155 K by cooling the samples. Meanwhile by heating the photosensitivity remained increased up to 235–245 K. Such phenomenon could presumably be attributed to the light-induced morphology changes of the sample material

Functional Properties of Thin Films of Deoxyribonucleic Acid with Poly(3,4-ethylenedioxythiophene) and Poly(styrenesulfonate) Complex and Bistability of Their Photocurrent

Functional photo- and electrical properties of thin films of DNA:PEDT-PSS were investigated. The sample current-voltage dependencies were linear and symmetrical down to liquid nitrogen temperature; the sample conductivity at 300 K was found to be 10(-10) Omega(-1)cm(-1). The thermal activation energy of the dark conductivity was about 33 meV independently on the applied bias in the temperature region between 200 K and 300 K. Carrier trapping was evidenced by the Thermally Stimulated Current method. Nevertheless this effect was weakly expressed, most probably because of the fast recombination of generated carriers. Notably, a bistable photoconduction behaviour was identified below the room temperature at constant light excitation. Upon illumination of the samples by similar to 500 nm - 800 nm light a marked increase of the photocurrent took place by cooling them below 140 K - 160 K. In contrast, by heating the photosensitivity remained increased up to 230 K - 240 K. This effect could be associated with the light-induced modification of charge transport conditions in the samples

Thin Films of DNA:PEDOT-PSS – Electrical and Optical Properties

Electrical, charge transport and optical properties of DNA:PEDOT-PSS thin films were investigated. Sample conductivity at room temperature was about (1–5) × 10−10 Ω−1 cm−1, IV curves being linear and symmetrical down to Liquid Nitrogen (LN) temperature. The thermal activation energy of the dark conduction near the room temperature was about 0.033 eV independently on the applied bias. The small effect of carrier trapping was evidenced by the Thermally Stimulated Current method, proving the fast recombination of light-generated carriers. Though, by constant light excitation a “bistable” photoconduction below the room temperature was identified. I.e., upon excitation by light from the spectral region ∼500–800 nm a notable increase of the photocurrent could be observed below 140–160 K by cooling the samples. Meanwhile by heating the photosensitivity remained increased up to 230–240 K. Most probably such phenomenon could be attributed to the light-induced morphology changes of the samples

Electrical and optical properties of thin films of DNA:PEDOT

We report investigations of functionalized DNA:PEDT–PSS films. The electrical conductivity of the sample material at the room temperature was about (1–5) × 10−10 Ω−1 cm−1. The IV curves of the samples were linear and symmetrical in the region from the room temperature down to the liquid nitrogen temperature. The thermal activation energy of the conductivity near the room temperature was about 0.033 eV independently on the applied bias. The weak carrier trapping was identified by the Thermally Stimulated Current method, proving the fast recombination of light-generated carriers. Notably, by constant light excitation a “bistable” photoconduction below the room temperature was evidenced, i.e., upon excitation by a white light a remarkable increase of the photocurrent could be observed below 145–155 K by cooling the samples. Meanwhile by heating the photosensitivity remained increased up to 235–245 K. Such phenomenon could presumably be attributed to the light-induced changes of the sample material morphology and/or associated variation of carrier transport conditions

Properties of functional DNA: PEDOT layers

We report investigations of functionalized DNA:PEDT-PSS films. The electrical conductivity of the samples material at the room temperature was about (1-5)10-10Ω-1cm-1. The IV curves of the samples were linear and symmetrical in the region from the room temperature down to the liquid Nitrogen temperature. The thermal activation energy of the conductivity near the room temperature was about 0.033 eV independently on the applied bias. The weak carrier trapping was identified by the Thermally Stimulated Current method, proving the fast recombination of light-generated carriers. Notably, by constant light excitation a "bistable" photoconduction below the room temperature was evidenced. I.e., upon excitation by white light a remarkable increase the photocurrent could be observed below 145-155 K by cooling the samples. Meanwhile by heating the photosensitivity increased up to 235-245 K. Such phenomenon could presumably be attributed to light-induced morphology changes of the sample material