The thermal contribution to photoactivation in A2 visual pigments studied by temperature effects on spectral properties

2003 ◽  
Vol 20 (4) ◽  
pp. 411-419 ◽  
Author(s):  
PETRI ALA-LAURILA ◽  
RAULI-JAN ALBERT ◽  
PIA SAARINEN ◽  
ARI KOSKELAINEN ◽  
KRISTIAN DONNER
Keyword(s):  
Temperature Effects ◽  
Spectral Properties ◽  
Crucian Carp ◽  
Rana Catesbeiana ◽  
Single Cells ◽  
Minimum Energy ◽  
Photoreceptor Cells ◽  
Visual Pigments ◽  
Small Shift ◽  
The Difference

Effects of temperature on the spectral properties of visual pigments were measured in the physiological range (5–28°C) in photoreceptor cells of bullfrog (Rana catesbeiana) and crucian carp (Carassius carassius). Absorbance spectra recorded by microspectrophotometry (MSP) in single cells and sensitivity spectra recorded by electroretinography (ERG) across the isolated retina were combined to yield accurate composite spectra fromca. 400 nm to 800 nm. The four photoreceptor types selected for study allowed three comparisons illuminating the properties of pigments using the dehydroretinal (A2) chromophore: (1) the two members of an A1/A2 pigment pair with the same opsin (porphyropsinvs.rhodopsin in bullfrog “red” rods); (2) two A2 pigments with similar spectra (porphyropsin rods of bullfrog and crucian carp); and (3) two A2 pigments with different spectra (rodsvs.long-wavelength-sensitive (L-) cones of crucian carp). Qualitatively, the temperature effects on A2 pigments were similar to those described previously for the A1 pigment of toad “red” rods. Warming caused an increase in relative sensitivities at very long wavelengths but additionally a small shift of λmaxtoward shorter wavelengths. The former effect was used for estimating the minimum energy required for photoactivation (Ea) of the pigment. Bullfrog rod opsin with A2 chromophore hadEa= 44.2 ± 0.9 kcal/mol, significantly lower (one-tailedP< 0.05) than the valueEa= 46.5 ± 0.8 kcal/mol for the same opsin coupled to A1. The A2 rod pigment of crucian carp hadEa= 42.3 ± 0.6 kcal/mol, which is significantly higher (one-tailedP< 0.01) than that of the L-cones in the same retina (Ea= 38.3 ± 0.4 kcal/mol), whereas the difference compared with the bullfrog A2 rod pigment is not statistically significant (two-tailedP= 0.13). No strict connection between λmaxandEaappears to exist among A2 pigments any more than among A1 pigments. Still, the A1 → A2 chromophore substitution in bullfrog opsin causes three changes correlated as originally hypothesized by Barlow (1957): a red-shift of λmax, a decrease inEa, and an increase in thermal noise.

Temperature effects on spectral properties of red and green rods in toad retina

2002 ◽  
Vol 19 (6) ◽  
pp. 781-792 ◽  
Author(s):  
PETRI ALA-LAURILA ◽  
PIA SAARINEN ◽  
RAULI ALBERT ◽  
ARI KOSKELAINEN ◽  
KRISTIAN DONNER
Keyword(s):  
Temperature Effects ◽  
Spectral Properties ◽  
Bufo Bufo ◽  
Relative Increase ◽  
Visual Pigments ◽  
Bufo Marinus ◽  
Temperature Changes ◽  
Long Wavelength ◽  
Cone Pigment ◽  
Effects Of Temperature

Temperature effects on spectral properties of the two types of rod photoreceptors in toad retina, “red” and “green” rods, were studied in the range 0–38°C. Absorbance spectra of the visual pigments were recorded by single-cell microspectrophotometry (MSP) and spectral sensitivities of red rods were measured by electroretinogram (ERG) recording across the isolated retina. The red-rod visual pigment is a usual rhodopsin (λmax = 503.6 nm and 502.3 nm at room temperature (21°C) in, respectively, Bufo marinus and Bufo bufo), that of green rods (λmax = 432.6 nm in Bufo marinus) belongs to the “blue” cone pigment family. In red rods, λmax depended inversely and monotonically on temperature, shifting by −2.3 nm when temperature was raised from 0°C to 38°C. Green-rod λmax showed no measurable dependence on temperature. In red rods, warming caused a relative increase of sensitivity in the long-wavelength range. This effect can be used for estimating the energy needed for photoexcitation, giving Ea = 44.3 ± 0.6 kcal/mol for Bufo marinus rhodopsin and 48.8 ± 0.5 kcal/mol for Bufo bufo rhodopsin. The values are significantly different (P < 0.001), although the two rhodopsins have very similar absorption spectra and thermal isomerization rates. Our recording techniques did not allow measurement of the corresponding effect at long wavelengths in green rods. Although spectral effects of temperature changes in the physiological range are small and of little significance for visual function, they reveal information about the energy states and different spectral tuning mechanisms of the visual pigments.

Modeling and simulation of saturated double rotor induction machine

2018 ◽  
Vol 37 (3) ◽  
pp. 1139-1165
Author(s):  
Koosha Choobdari Omran ◽  
Ali Mosallanejad
Keyword(s):  
Temperature Effects ◽  
Power Efficiency ◽  
Reactive Power ◽  
Induction Machine ◽  
Transient Behavior ◽  
State Equations ◽  
Content Type ◽  
Proposed Model ◽  
The Difference ◽  
Park Transformation

Purpose Double rotor induction machine (DRIM) is a particular type of induction machine (IM) that has been introduced to improve the parameters of the conventional IM. The purpose of this study is to propose a dynamic model of the DRIM under saturated and unsaturated conditions by using the equations obtained in this paper. Also, skin and temperature effects are considered in this model. Design/methodology/approach First, the DRIM structure and its performance will be briefly reviewed. Then, to realize the DRIM model, the mathematical equations of the electrical and mechanical part of the DRIM will be presented by state equations in the q-d axis by using the Park transformation. In this paper, the magnetizing fluxes saturation is included in the DRIM model by considering the difference between the amplitudes of the unsaturated and saturated magnetizing fluxes. The skin and temperature effects are also considered in this model by correcting the rotor and stator resistances values during operation. Findings To evaluate the effects of the saturation and skin effects on DRIM performance and validate the model, the machine is simulated with/without consideration of saturation and skin effects by the proposed model. Then, the results, including torque, speed, stator and rotor currents, active and reactive power, efficiency, power factor and torque-speed characteristic, are compared. In addition, the performance of the DRIM has been investigated at different speed conditions and load variations. The proposed model is developed in Matlab/Simulink for the sake of validation. Originality/value This paper presents an understandable model of DRIM with and without saturation, which can be used to analyze the steady-state and transient behavior of the motor in different situations.

Interactions of blastomeres suggest changes in cell surface adhesiveness during the formation of inner cell mass and trophectoderm in the preimplantation mouse embryo

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 133-152
Author(s):  
Susan J. Kimber ◽  
M. Azim ◽  
H. Surani ◽  
Sheila C. Barton
Keyword(s):  
Inner Cell Mass ◽  
Single Cells ◽  
Cell Mass ◽  
Cell Stage ◽  
Trophectoderm Cells ◽  
Adhesive Surface ◽  
Preimplantation Mouse Embryo ◽  
Divergent Differentiation ◽  
Preimplantation Mouse ◽  
The Difference

Whole 8-cell morulae can be aggregated with isolated inner cell masses from blastocysts. On examining semithin light microscope sections of such aggregates we found that cells of the morula changed shape and spread over the surface of the ICM, thus translocating it to the inside of the aggregate. Using single cells from 8-cell embryos in combination with single cells from other stage embryos or isolated ICMs we show that 1/8 blastomeres spread over other cells providing a suitably adhesive surface. The incidence of spreading is high with inner cells from 16-cell embryos (56 %) and 32-cell embryos (62%) and isolated inner cell masses (64%). In contrast, the incidence of spreading of 1/8 blastomeres is low over outer cells from 16-cell embryos (26%) and 32-cell embryos (13%). Blastomeres from 8-cell embryos do not spread over unfertilized 1-cell eggs, 1/2 or 1/4 cells or trophectoderm cells contaminating isolated ICMs. When 1/8 cells are aggregated in pairs they flatten on one another (equal spreading) as occurs at compaction in whole 8-cell embryos. However, if 1/8 is allowed to divide to 2/16 in culture one of the cells engulfs the other (51-62/ pairs). Based on the ideas of Holtfreter (1943) and Steinberg (1964,1978) these results are interpreted to indicate an increase in adhesiveness at the 8-cell stage as well as cytoskeletal mobilization. Following the 8-cell stage there is an increase in adhesiveness of inside cells while the outside cells decrease in adhesiveness. The difference in adhesiveness between inside and outside cells in late morulae is probably central to the divergent differentiation of (inner) ICM and (outer) trophectoderm cell populations.

Compositional Modulation and its Optoelectric Properties of Zn(S,Se,Te) Crystals Grown by Hydrogen Radical-Enhanced CVD

1995 ◽  
Vol 417 ◽  
Author(s):  
Hiroyuki Fujiwara ◽  
Toshihiro Ii ◽  
Isamu Shimizu
Keyword(s):  
Deep Level ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Small Shift ◽  
X Ray ◽  
Compositional Modulation ◽  
Peak Energy ◽  
Large Lattice ◽  
The Difference ◽  
Hydrogen Radical

AbstractHigh-quality (ZnS)n(ZnSe)12n and (ZnSe)n(ZnTe)11n (n=1∼4) crystals were grown at a low temperature of 200°C by hydrogen radical-enhanced chemical vapor deposition. From satellite peaks in x-ray diffraction spectra, these periodic structure crystals were confirmed to be grown coherently on substrates, in spite of large lattice mismatches between the grown layers and the substrates (͛=4∼7%). In photoluminescence (PL) spectra of these films, strong band-edge emissions were predominantly observed, resulting from a suppression of deep-level emissions. We found that the PL peak energy of (ZnSe)n(ZnTe)11n shifts systematically to lower energy by 200 meV with changes in the number of ZnSe layers (n), while relatively small shift of 13 meV was observed in (ZnS)n(ZnSe)12n. These discrepancy can be attributed to the difference of band-lineups or chemical natures of constituent atoms in these crystals.

scholarly journals Temperature effects on the spectral properties of colloidal CdSe nanodots, nanorods, and tetrapods

2007 ◽  
Vol 90 (9) ◽  
pp. 093104 ◽  
Author(s):  
A. Al Salman ◽  
A. Tortschanoff ◽  
M. B. Mohamed ◽  
D. Tonti ◽  
F. van Mourik ◽  
...  
Keyword(s):  
Temperature Effects ◽  
Spectral Properties

scholarly journals 1D1515 Determinant of rapid phosphorylation of visual pigments in cone photoreceptor cells

2002 ◽  
Vol 42 (supplement2) ◽  
pp. S26
Author(s):  
S. Tachibanaki ◽  
S. Tsushima ◽  
Y. Shimauchi-Matsukawa ◽  
S. Kawamura
Keyword(s):  
Photoreceptor Cells ◽  
Visual Pigments ◽  
Cone Photoreceptor

scholarly journals Active and passive electrical properties of single bullfrog atrial cells.

1981 ◽  
Vol 78 (1) ◽  
pp. 19-42 ◽  
Author(s):  
J R Hume ◽  
W Giles
Keyword(s):  
Rana Catesbeiana ◽  
Single Cells ◽  
Input Resistance ◽  
Isolated Cells ◽  
Atrial Cells ◽  
Long Duration ◽  
Electrophysiological Measurements ◽  
3 Omega ◽  
Passive Electrical Properties ◽  
Atrial Cell

Single cells from the bullfrog (Rana catesbeiana) atrium have been prepared by using a modification of the enzymatic dispersion procedure described by Bagby et al. (1971. Nature [Long.]. 234:351--352) and Fay and Delise (1973. Proc. Natl. Acad. Sci. U.S.A. 70:641--645). Visualization of relaxed cells via phase-contrast or Nomarski optics (magnification, 400--600) indicates that cells range between 150 and 350 micrometers in length and 4 and 7 micrometers in diameter. The mean sarcomere length in relaxed, quiescent atrial cells in 2.05 micrometer. Conventional electrophysiological measurements have been made. In normal Ringer's solution (2.5 mM K+, 2.5 mM Ca++) acceptable cells have stable resting potentials of about -88 mV, and large (125 mV) long-duration (approximately 720 ms) action potentials can be elicited. The Vm vs. log[K+]0 relation obtained from isolated cells is similar to that of the intact atrium. The depolarizing phase of the action potential of isolated atrial myocytes exhibits two pharmacologically separable components: tetrodotoxin (10(-6) g/ml) markedly suppresses the initial regenerative depolarization, whereas verapamil (3 x 10(-6) M) inhibits the secondary depolarization and reduce the plateau height. A bridge circuit was used to estimate the input resistance (220 +/- 7 M omega) and time constant 20 +/- 7 ms) of these cells. Two-microelectrode experiments have revealed small differences in the electrotonic potentials recorded simultaneously at two different sites within a single cell. The equations for a linear, short cable were used to calculate the electrical constants of relaxed, single atrial cells: lambda = 921.3 +/- 29.5 micrometers; Ri = 118.1 +/- 24.5 omega cm; Rm = 7.9 +/- 1.2 x 10(3) omega cm2; Cm = 2.2 +/- 0.3 mu Fcm-2. These results and the atrial cell morphology suggest that this preparation may be particularly suitable for voltage-clamp studies.

Temperature Effects on Photocurrent Generation in Polymer Hetero—Junction Photovoltaic Devices

2004 ◽  
Vol 836 ◽  
Author(s):  
Mi Yeon Song ◽  
Kang-Jin Kim ◽  
Dong Yong Kim
Keyword(s):  
Dark Current ◽  
Temperature Effects ◽  
Carrier Transport ◽  
Photovoltaic Device ◽  
Space Charge Limited Current ◽  
Photovoltaic Devices ◽  
Charge Mobility ◽  
Photocurrent Generation ◽  
The Difference ◽  
Photovoltaic Characteristics

ABSTRACTIn a heterojunction photovoltaic device of ITO/TiO2/poly(3-alkylthiophene)/Au, the photocurrent was characterized with different temperature by using regio-random (P3HT), regular (RP3HT) poly(3-hexylthiophene) and regio-regular poly(3-dodecylthiophene)(RP3DT). The regio-regularity and alky chain length affected the photovoltaic characteristics due to the difference in the hole carrier transport. The drift charge mobility of those devices were analyzed by the space charge limited current (SCLC) theory using dark current versus bias relations. The photocurrent in the devices based on poly(3-alkylthiopene)s began to decrease rapidly below a temperature at which the drift charge mobility was 10−5 cm2/V.s.

scholarly journals Development of a Microfluidic GHz Impedance Cytometer

2013 ◽  
Vol 80 (12) ◽  
Author(s):  
Niels Haandbæk ◽  
Sebastian C. Bürgel ◽  
Flavio Heer ◽  
Andreas Hierlemann
Keyword(s):  
Dielectric Properties ◽  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Single Cells ◽  
Chinese Hamster ◽  
Frequency Range ◽  
Cell Nuclei ◽  
Dielectric Characterization ◽  
The Difference

AbstractThis article presents a novel microfluidic impedance cytometer enabling dielectric characterization of single cells at frequencies up to 500 MHz. The dielectric properties of cells at lower frequencies contain information about their size and membrane capacitance. The increased frequency range of the presented cytometer potentially allows for characterization of intracellular components, such as vacuoles or the cell nuclei. We demonstrate the overall capabilities of the cytometer through discrimination of polystyrene beads from Chinese hamster ovary (CHO) cells. The discrimination is based on the difference in dielectric properties at frequencies up to 500 MHz.

SPECTRAL PROPERTIES OF DERIVATIVE OPERATORS IN THE BASIS-SPLINE COLLOCATION METHOD

1995 ◽  
Vol 06 (01) ◽  
pp. 143-167 ◽  
Author(s):  
J.C. WELLS ◽  
V.E. OBERACKER ◽  
M.R. STRAYER ◽  
A.S. UMAR
Keyword(s):  
Collocation Method ◽  
Spectral Properties ◽  
High Order ◽  
Collocation Methods ◽  
Finite Difference Schemes ◽  
Spline Collocation ◽  
Spline Collocation Method ◽  
The Difference ◽  
Order Spline ◽  
The One

We discuss the basis-spline collocation method for the lattice solution of boundary-value differential equations, drawing particular attention to the difference between lattice and continuous collocation methods. Spectral properties of the basis-spline lattice representation of the first and second spatial derivatives are studied for the case of periodic boundary conditions with homogeneous lattice spacing and compared to spectra obtained using traditional finite-difference schemes. Basis-spline representations are shown to give excellent resolution on small-length scales and to satisfy the chain rule with good fidelity for the lattice-derivative operators using high-order splines. Application to the one-dimensional Dirac equation shows that very high-order spline representations of the Hamiltonian on odd lattices avoid the notorious spectral-doubling problem.

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