Temat: square-wave - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Electroporated intact BY-2 tobacco culture cells as a model of transient expression study.
Autorzy:: Kościańska, Edyta
Wypijewski, Krzysztof
Tematy:: transfection
square-wave electroporator
BY-2 cells; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1044095.pdf Link otwiera się w nowym oknie
Opis:: Transfer of foreign genes into plant cells can be accomplished by several methods: agrobacterium-mediated, microinjection, biolistic particle bombardment and electroporation. The last one is frequently used for transfection of plant protoplasts for transient gene expression. Electroporation is a simple procedure and allows transfecting a large number of cells at one time. Square wave-modulated porators are the most efficient for introducing expression cassettes into plant protoplasts. Based on a protocol developed by Wu & Feng (Plant Cell Reports, 1999, 18, 381-386), we optimized conditions for transfection of intact Nicotiana tabacum BY-2 cells using square wave-modulated electroporator. To simplify screening for transfected gene expression we used constructs with a GFP marker gene.Electroporation of cells in the presence of DNA has been widely used in recent years in molecular biology for studying transient gene expression. It consists in subjecting cells to an electric field, which forms pores in the lipid bilayer of the cell membrane, allowing DNA molecules to enter into the cytoplasm [1]. Pore formation is reversible and cell survival is maintained, thus such a method of introducing foreign DNA into cells is fast, simple, efficient, non-toxic and applicable to a great variety of cells. However, in spite of all its advantages electroporation has not been applied equally successfully in experiments with plant cells (except those with protoplasts) because of the cell wall. There are some earlier reports indicating that the cell wall does not prevent DNA molecules from being internalized [1-3]. In 1999 Wu and Feng [4] described an effective method of electroporation applicable to the intact plant cells. In this method plant cells are subjected to plasmolysis prior to electroporation. The modifications of these procedure are presented in this paper.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: A fault diagnosis method for substation grounding grid based on the square-wave frequency domain model
Autorzy:: Zhang, P.-H.
He, J.-J.
Zhang, D.-D.
Wu, L.-M.
Tematy:: square-wave
frequency characteristics
grounding grid
fault diagnosis; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/221635.pdf Link otwiera się w nowym oknie
Opis:: Current methods of fault diagnosis for the grounding grid using DC or AC are limited in accuracy and cannot be used to identify the locations of the faults. In this study, a new method of fault diagnosis for substation grounding grids is proposed using a square-wave. A frequency model of the grounding system is constructed by analyzing the frequency characteristics of the soil and the grounding conductors into which two different frequency square-wave sources are injected. By analyzing and comparing the corresponding information of the surface potentials of the output signals, the faults of the grounding grid can be diagnosed and located. Our method is verified by software simulation, scale model experiments and field experiments.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Time-dependent growth of the dendritic silver prepared using square wave voltammetry technique for methylene blue photodegradation
Autorzy:: Budi, Setia
Dhanasmoro, Lintang
Purwanto, Agung
Muhab, Sukro
Tematy:: Square-wave voltammetry
dendritic Ag
photocatalysis
photodegradation of methylene blue; Pokaż więcej
Wydawca:: Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Powiązania:: https://bibliotekanauki.pl/articles/1849284.pdf Link otwiera się w nowym oknie
Opis:: Silver (Ag) particle is a promising photocatalyst material with relatively high catalytic activity and good absorption in the visible light region. A dendritic structure of Ag has been studied in the purpose to enhance photocatalytic activity due to a large surface area and active site number of the metallic Ag particles. In this work, the Ag dendritic structure was synthesized from a surfactant-free electrolyte using the square wave voltammetry technique. The time-dependent growth of the Ag dendrites and their photocatalytic activity on methylene blue (MB) photodegradation are reported. Morphological analysis exhibits the fractal dendritic structure of Ag was found to continuously grow by increasing the deposition time. The Ag dendrites showed a low charge transfer resistance (366.21 Ω) and high specific capacitance (2.09 F/g). A high rate of MB degradation (45.57%) under ultraviolet irradiation indicated that the Ag dendrites produced using this technique are effective for the photocatalytic degradation of MB dye.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Investigation of the feasibility of a flow system for the determination of vitamin D3 in pharmaceutical preparations
Zbadanie możliwości zastosowania układu przepływowego do oznaczania witaminy D3 w preparatach farmaceutycznych
Autorzy:: Reizer, Karolina
Opis:: The presented research allowed the development of a voltammetric method for the determination of vitamin D3 in pharmaceutical preparations under flow-through conditions. The working electrode was an unmodified glassy carbon electrode. The role of the auxiliary electrode was played by the truncated tip of the steel needle. The supporting electrolyte was a solution of ethanol + LiClO4(aq) in a 9:1 (v/v) ratio. The preparation of samples in the form of drops was based on a simple pipetting of a defined volume of the preparation, while the capsules were pierced and the contents eluted with ethanol.Parameters such as flow rate, measurement scheme and the diameter of the tube supplying the solutions to the measuring vessel were optimized. As a result, it was possible to determine cholecalciferol from pharmaceutical preparations (dops and capsules) at the micromole level. Quantitative analysis was performed using three calibration methods: standard series method, standard addition method (SAM) and the signal increament standard addition method (SISAM). The determined concentrations were compared with the concentration values declared by the manufacturers, and the limit of detection, which was of 1,0 μM and the limit of quantification, which reached 3,2 μM were calculated. The accuracy errors determined by the SISAM method ranged from 0,9% to 2,7% for drops (omitting Devikap containing anethole in its composition) and 10,2% for capsules, while the precision of the method was 97,6 %.
Przedstawione badania pozwoliły na opracowanie woltamperometrycznej metody oznaczania witaminy D3 w preparatach farmaceutycznych w warunkach przepływowych. Elektrodę pracującą stanowiła niemodyfikowana elektroda z węgla szklistego. Rolę elektrody pomocniczej pełniła ścięta końcówka stalowej igły. Elektrolitem podstawowym był roztwór etanol + LiClO4(aq) w stosunku 9:1 (v/v). Przygotowanie próbek w formie kropli opierało się na prostym pobraniu określonej objętości preparatu, natomiast kapsułki przekłuwano i wymywano zawartość przy użyciu etanolu.Optymalizacji poddano takie parametry jak: natężenie przepływu, schemat wykonywania pomiarów oraz średnicę przewodu doprowadzającego roztwory do naczynka pomiarowego. Dzięki temu udało się oznaczyć cholekalcyferol pochodzący z preparatów farmaceutycznych (kropli oraz kapsułek) na poziomie mikromolowym. Analiza ilościowa została wykonana z zastosowaniem trzech metod kalibracyjnych: metody serii wzorców, metody dodatków wzorca (SAM) oraz zmodyfikowanej metody dodatków wzorca (SISAM). Wyznaczone stężenia zestawiono z wartościami stężeń deklarowanymi przez producentów, a także obliczono granicę wykrywalności, która wyniosła 1,0 μM i granicę oznaczalności, która osiągnęła wartość 3,2 μM. Błędy dokładności wyznaczone metodą SISAM zawierały się w granicach 0,9% – 2,7% dla kropli (pomijając Devikap zawierający w składzie anetol) i 10,2% dla kapsułek, natomiast precyzja metody była na poziomie 97,6%.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 5.

Tytuł:: Electrochemical direct injection detector for vitamin D3 determination
Elektrochemiczny detektor bezpośredniego wstrzyku do oznaczania witaminy D3
Autorzy:: Zabiegaj, Marcin
Opis:: The research allowed the development of a method for determining vitamin D3 in pharmaceuticals using square wave voltammetry (SWV in a flow system). The measurement system consisted of an unmodified glassy carbon working electrode, a Cl-Ag double-jacketed reference electrode, an auxiliary electrode in the form of a truncated steel needle tip, a 40 µL electromagnetic pump, and teflon tubing. The base electrolyte used was a 9:1 solution of ethanol + LiClO4(Aq). In the system under study, aspects such as the effect of cleaning and conditioning of the system, the waiting time from the introduction of the sample into the vessel to the start of the measurement, and the spatial arrangement of the system were optimized. The determination of cholecalciferol in pharmaceutical preparations containing it, both drugs and dietary supplements, was carried out. Three calibration methods were used: standard series method, standard additive method (SAM), and modified standard additive method (SISAM). The concentrations obtained were compared with those declared by the manufacturers, and the limits of detection and quantification of the prepared method were calculated. These were 0.71 and 2.34 µM, respectively.The system was modified to use a direct injection detector (DID) by attaching a 20 µL pump. Measurements were carried out in a model system for two standards of different concentrations, investigating for which mixing ratio the best determination accuracy is obtained. Next, an attempt was made to determine pharmaceutical preparations against a vitamin D3 standard. Using the method of "two-point" calibration curves and appropriate adjustment of the mixing ratio, the concentrations of cholecalciferol in pharmaceutical preparations were calculated.
Przeprowadzone badania pozwoliły na opracowanie metody oznaczania witaminy D3 w preparatach farmaceutycznych z użyciem techniki woltamperometrii fali prostokątnej (SWV) w układzie przepływowym. Układ pomiarowy składał się z niemodyfikowanej elektrody pracującej z węgla szklistego, chlorosrebrowej elektrody odniesienia z podwójnym płaszczem, elektrody pomocniczej w formie ściętej końcówki stalowej igły, pompy elektromagnetycznej 40 µL oraz teflonowych wężyków. Użytym elektrolitem podstawowym był roztwór etanol + LiClO4(Aq) w stosunku 9:1. W badanym układzie optymalizacji poddano aspekty takie jak: wpływ czyszczenia i kondycjonowania układu, czas oczekiwania od momentu wprowadzenia próbki do naczynka do rozpoczęcia pomiaru oraz ułożenie przestrzenne układu. Dokonano oznaczenia cholekalcyferolu w preparatach farmaceutycznych go zawierających, zarówno leków jak i suplementów diety. Użyto trzech metod kalibracyjnych: metody serii wzorców, dodatków wzorca (SAM) oraz zmodyfikowanej metody dodatków wzorca (SISAM). Zestawiono otrzymane stężenia z deklarowanymi przez producentów oraz wyliczono granice wykrywalności oraz oznaczalności opracowanej metody. Wynosiły one odpowiednio 0,71 oraz 2,34 µM.Zmodyfikowano układ w celu zastosowania detektora bezpośredniego wstrzyku (DID) poprzez dołączenie pompy 20 µL. Przeprowadzono pomiary w układzie modelowym dla dwóch wzorców o różnych stężeniach badając dla jakiego stosunku mieszania uzyskuje się najlepszą dokładność oznaczenia. Następnie dokonano próby oznaczenia analitu w preparatach farmaceutycznych. Korzystając z metody „dwupunktowych” krzywych kalibracyjnych oraz odpowiedniego dopasowania stosunku mieszania wyliczono stężenia cholekalcyferolu w preparatach farmaceutycznych.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 6.

Tytuł:: An Investigation on Acoustic Wave Focalization by a Square Lattice Flat Lens
Autorzy:: Alagoz, S.
Tematy:: square lattice sonic crystal
wave focusing
plane-wave expansion method
FDTD simulation; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/177219.pdf Link otwiera się w nowym oknie
Opis:: A sonic crystal consists of a finite-size periodic array of scatters embedded in a background material. One of the fascinating properties of sonic crystals is the focusing phenomenon. In this study, the near field focusing effect of a solid-air 2D sonic crystal lens with a square lattice configuration is investigated in the second frequency band. The band structure and equifrequency contour of the crystal are analyzed to reveal the dispersion of an acoustic wave on the crystal structure. The frequency dependence of the acoustic wave focalization by the sonic crystal flat lens is demonstrated via Finite Difference Time Domain simulation results and experimental measurements.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Simulation of two dimensional photonic band gaps
Autorzy:: Dissanayake, S. E.
Wijewardena Gamalath, K. A. I. L.
Tematy:: Photonic crystal
square lattice
triangular lattice
honeycomb lattice
plane wave expansion
mode field distribution
GaAs
dielectric kontrast
filling fraction
gap maps; Pokaż więcej
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:: https://bibliotekanauki.pl/articles/411904.pdf Link otwiera się w nowym oknie
Opis:: The plane wave expansion method was implemented in modelling and simulating the band structures of two dimensional photonic crystals with square, triangular and honeycomb lattices with circular, square and hexagonal dielectric rods and air holes. Complete band gaps were obtained for square lattice of square GaAs rods and honeycomb lattice of circular and hexagonal GaAs rods as well as triangular lattice of circular and hexagonal air holes in GaAs whereas square lattice of square or circular air holes in a dielectric medium ε = 18 gave complete band gaps. The variation of these band gaps with dielectric contrast and filling factor gave the largest gaps for all configurations for a filling fraction around 0.1.The gap maps presented indicated that TM gaps are more favoured by dielectric rods while TE gaps are favoured by air holes. The geometrical gap maps operating at telecommunication wavelength λ = 1.55 m showed that a complete band gap can be achieved for triangular lattice with circular and hexagonal air holes in GaAs and for honeycomb lattice of circular GaAs rods.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Description of Residual Stress Distribution in the Surface Layer After Heat Treatment and Shot Peening
Autorzy:: Skalski, Konstanty
Mońka, Grzegorz
Filipowski, Ryszard
Tematy:: X-ray diffractometer
measurement of stresses
psi sine square method
metal crystal lattice
wave beam diffraction
pneumatic shot peening
multiple regression
planned experiment; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Powiązania:: https://bibliotekanauki.pl/articles/36827665.pdf Link otwiera się w nowym oknie
Opis:: The stress distribution function in the surface layer is created as a result of using stress measurements on the surfaces of C45 steel samples after shot peening. Stresses were measured by X-ray diffraction with the use of the PSF-3M device from the Rigaku Company. For measuring residual stresses, subsequent layers of the top surface of the material were used as a basis, and these were obtained through electrochemical etching. The test results i.e. distance into the material, sample hardness, shot type, stress) were entered into the stepwise multiple regression program. A record of residual stresses was obtained in the form of the second-degree regression function of three independent variables with interactions. The obtained analytical form of the residual stress function was used in the FUNVAL3.EXE program to calculate the tabular values of stresses permeating into the material. For the analytical description of the stress distribution, the REGPOLY.EXE regression program was used, which creates a polynomial functional form of the residual stress distribution. The plot form of the residual stress distribution was obtained using the EXCEL Microsoft Office 2000 program.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Real time quantum tunneling through a double square barrier
Autorzy:: Papadopoulos, George J.
Tematy:: double square barrier propagator
probability density
current density
wave packet
transmitted probability
propagator z podwójną barierą kwadratową
gęstość prawdopodobieństwa
gęstość prądu
pakiet falowy
prawdopodobieństwo transmisji; Pokaż więcej
Wydawca:: Politechnika Gdańska
Powiązania:: https://bibliotekanauki.pl/articles/61030206.pdf Link otwiera się w nowym oknie
Opis:: The propagator of a one-dimensional double square barrier is obtained analytically in terms of the relevant eigenfunctions. With the aid of the propagator the wavefunction evolution for a particle, initially in a state of wave packet, located on the left-hand side of the barrier, with ignorable overlap with the barrier, is obtained. There follows study of the probability and current densities stemming from the particle initial state. In particular, the space distributions at given times of the above densities are given. Furthermore, their evolution in time at the entrance and exit of the barrier is obtained. The numerical results show repeated reversal in the current density at the barrier entrance, while being unidirectional at the exit. However, the probability of entering the barrier over an extremely long time tends to equal the corresponding probability of exiting the barrier. Owing to the fact that the wave packet expands on both of its sides, as time goes by, it is possible to have transmission even if the particle's initial momentum points away from the barrier. The effect, in question, becomes evident in diagrams for the transmitted probability beyond the barrier exit in terms of the particle initial momentum, over a region.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Metody obliczania napięcia międzyfazowego z symulacji komputerowych
Methods for calculation interfacial tension from computer simulations
Autorzy:: Chrzanowski, J.
Lamperski, S.
Tematy:: napięcie międzyfazowe
symulacja komputerowa
metoda Kirkwooda-Buffa
metoda Bennetta
metoda test-area
układ rozszerzony
funkcja fali kapilarnej
metoda kwadratu gradientu
interfacial tension
computer simulation
Kirkwood-Buff method
Bennetts method
test-area method
expanded ensemble simulation
capillary wave theory
square gradient theory; Pokaż więcej
Wydawca:: Polskie Towarzystwo Chemiczne
Powiązania:: https://bibliotekanauki.pl/articles/172418.pdf Link otwiera się w nowym oknie
Opis:: Interfaces have been recently a subject of profound interest for physicists, chemists and biologists because of the processes taking place in the interfacial region like adsorption, catalysis of chemical reactions etc. Computer simulations treat an interface in a full atomic level and by that they are a valuable complementary technique for experiment and theory. In this paper, different methods for the calculation of an interfacial tension by computer simulations are described and compared. The most commonly used method for the interfacial tension calculation was developed by Kirkwood-Buff. It is based on the mechanical route definition. This approach uses normal and tangential pressure components of the pressure tensor. The interfacial tension can be also evaluated through its thermodynamic definition. The method of Bennett defines the interfacial tension as the free energy difference of two (or more) systems relative to the difference in interfacial areas. The “test- -area” method is based upon the perturbation formalism. The test state is obtained from an infinitesimal change of the surface area of the reference system. The third method based on the thermodynamic route used to evaluate the interfacial tension is thought as an expanded ensemble simulation where two systems with different free energy and the interfacial area are connected by a discrete chain of intermediate subsystems. The next approach is based on the capillary wave theory formalism which provides a relationship between the surface tension and the wave width due the capillarity broadening. Interfacial tension may be also computed from the square gradient theory which is based on the expansion of the Hemholtz free energy in the Taylor series around the homogeneous state with the assumption that the molecular gradients in the interface are small compared to intermolecular distance. The theoretical basis, application and results of computer simulations of each method are presented. Aa accuracy of the methods in different simulation methodologies and systems is compared.
Dostawca treści:: Biblioteka Nauki

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