Wyniki wyszukiwania - Biblioteka Nauki

1

Chlorophyll fluorimetry as a method for studying light absorption by photosynthetic pigments in marine algae

100%

Matorin D. N. , Antal T. K. , Ostrowska M. , Rubin A. B. , Ficek D. , Majchrowski R.

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2004

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tom No. 46 (4)

519-531

EN

Using laboratory cultures of algae and natural phytoplankton populations from Nhatrang Bay (South China Sea), the relationship between the chlorophyll fluorescence F0, the chlorophyll a concentration Ca and light absorption capacities of algae cells was studied. It is shown that the ratio F0/Ca depends mainly on the species composition of the algae population; hence, the concentration Ca can be measured with the fluorescence method with acceptable accuracy only when the species composition of algae populations varies over a rather narrow range. The fluorescence F0 can, however, be a good index of the total absorption capacities of different phytoplankton species, because the intensity of F0 depends on the sum total of light absorbed by all photosynthetic pigments in a plant cell. Thus, the fluorescence F0 measures not only the concentration of chlorophyll a, but that of all photosynthetic pigment concentrations.

2

Spectra of light absorption by phytoplankton pigments in the Baltic; conclusions to be drawn from a Gaussian analysis of empirical data

88%

Ficek D. , Kaczmarek S. , Ston-Egiert J. , Wozniak B. , Majchrowski R. , Dera J.

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2004

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tom 46

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nr 4

EN

Analysed by differential spectroscopy, 1208 empirical spectra of light absorption apl(λ) by Baltic phytoplankton were spectrally decomposed into 26 elementary Gaussian component bands. At the same time the composition and concentrations of each of the 5 main groups of pigments (chlorophylls a, chlorophylls b, chlorophylls c, photosynthetic carotenoids and photoprotecting carotenoids) were analysed in 782 samples by HPLC. Inspection of the correlations between the intensities of the 26 elementary absorption bands and the concentrations of the pigment groups resulted in given elementary bands being attributed to particular pigment groups and the spectra of the mass-specific absorption coefficients established for these pigment groups. Moreover, balancing the absorption effects due to these 5 pigment groups against the overall absorption spectra of phytoplankton suggested the presence of a sixth group of pigments, as yet unidentified (UP), undetected by HPLC. Apr eliminary mathematical description of the spectral absorption properties of these UP was established. Like some forms of phycobilins, these pigments are strong absorbers in the 450–650 nm spectral region. The packaging effect of pigments in Baltic phytoplankton was analysed statistically, then correlated with the concentration of chlorophyll a in Baltic water. As a result, a Baltic version of the algorithm of light absorption by phytoplankton could be developed. This algorithm can be applied to estimate overall phytoplankton absorption spectra and their components due to the various groups of pigments from a knowledge of their concentrations in Baltic water.

3

Orientational behaviour of some homologues of 4-n-pentyl-phenylthio-4'-n-alkoxybenzoate doped with dichroic dye

75%

Bauman D. , Zięba A. , Mykowska E.

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tom Vol. 16, No. 3

244-250

EN

The long-range orientational order of three members of 4-n-pentylphenylthio-4'-n-alkoxybenzoate (nS5) series doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters and as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A, and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. Moreover, the dependence of the order parameter values on the length of the alkoxy chain in liquid crystal molecules was found. It was shown that the order parameter , obtained from fluorescence measurements, can be helpful in recognizing the second-order or weakly first-order transitions between various liquid crystalline phases.

4

Investigation of silver nanoparticles embedded in extracted gelatins from camel, bovine, and fish bones for possible use in radiation dosimetry

75%

Alrashidi T. K. , Aljuhani A. , Almugaiteeb F. , Badi N. , Al-Aoh H. A. , Alghamdi S. A. , Alsharari A. M. , Alzahrani A. O. M. , Almalki K.

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2023

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tom Vol. 41, No. 4

1--12

EN

Gelatins from camel, bovine, and fish bones were successfully extracted by using chemical pretreatment and heating methods. The bones were demineralized for 3 days at ambient temperature using hydrochloric acid solutions (0.5–1 M), and the collagen was partially hydrolyzed by preheating in distilled water at 75–80°C for 3 h, followed by extraction temperature at 90°C for 1 h. Free-standing films of gelatin entrained with silver nanoparticles (Gel/AgNPs) at low concentrations (1.25, 2.5, and 5 mM) were synthesized as radiation dosimeters. A high-energy ultrasonic homogenizer was used to dissolve the gelatin in distilled water and to disperse the AgNPs in the gelatin. The nanocomposites’ morphology and crystallinity were investigated using scanning electron microscopy (SEM), optical absorption, and Fourier transform infrared (FTIR) spectroscopies. Dose enhancement was assessed using X-ray irradiations with beam energies below and above silver K-edge. The beam was configured by setting the X-ray generator at 15, 25.5, and 35 kV potential and a beam current of 1 mA. An X-ray detector is used to detect the number of electrons after passing through Gel/AgNPs samples. The use of AgNPs embedded in gelatin caused the enhancement of X-ray radiation absorption, and the highest percentage of linearity for the dosimeter was found to be 90% in the optical range of 395 nm to 425 nm. The preliminary results demonstrated that Gel/AgNPs material may be used in radiation dosimetry for low-energy radiotherapy sources.

5

Spectra of light absorption by phytoplankton pigments in the Baltic; conclusions to be drawn from a Gaussian analysis of empirical data

75%

Ficek D. , Kaczmarek S. , Stoń-Egiert J. , Woźniak B. , Majchrowski R. , Dera J.

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2004

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tom No. 46 (4)

533-555

EN

Analysed by differential spectroscopy, 1208 empirical spectra of light absorption apl(?) by Baltic phytoplankton were spectrally decomposed into 26 elementary Gaussian component bands. At the same time the composition and concentrations of each of the 5 main groups of pigments (chlorophylls a, chlorophylls b, chlorophylls c, photosynthetic carotenoids and photoprotecting carotenoids) were analysed in 782 samples by HPLC. Inspection of the correlations between the intensities of the 26 elementary absorption bands and the concentrations of the pigment groups resulted in given elementary bands being attributed to particular pigment groups and the spectra of the mass-specific absorption coefficients established for these pigment groups. Moreover, balancing the absorption effects due to these 5 pigment groups against the overall absorption spectra of phytoplankton suggested the presence of a sixth group of pigments, as yet unidentified (UP), undetected by HPLC. A preliminary mathematical description of the spectral absorption properties of these UP was established. Like some forms of phycobilins, these pigments are strong absorbers in the 450-650 nm spectral region. The packaging effect of pigments in Baltic phytoplankton was analysed statistically, then correlated with the concentration of chlorophyll a in Baltic water. As a result, a Baltic version of the algorithm of light absorption by phytoplankton could be developed. This algorithm can be applied to estimate overall phytoplankton absorption spectra and their components due to the various groups of pigments from a knowledge of their concentrations in Baltic water.

6

Modelling the light absorption properties of particulate matter forming organic particles suspended in sea water. Part 3. Practical applications

75%

Wozniak B. , Wozniak S. B. , Tyszka K. , Ostrowska M. , Ficek D. , Majchrowski R. , Dera J.

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nr 4

7

Modelling light and photosynthesis in the marine environment

63%

Woźniak B. , Dera J. , Ficek D. , Majchrowski R. , Ostrowska M. , Kaczmarek S.

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2003

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tom No. 45 (2)

171-245

EN

The overriding and far-reaching aim of our work has been to achieve a good understanding of the processes of light interaction with phytoplankton in the sea and to develop an innovative physical model of photosynthesis in the marine environment, suitable for the remote sensing of marine primary production. Unlike previous models, the present one takes greater account of the complexity of the physiological processes in phytoplankton. We have focused in particular on photophysiological processes, which are governed directly or indirectly by light energy, or in which light, besides the nutrient content in and the temperature of seawater, is one of the principal limiting factors. To achieve this aim we have carried out comprehensive statistical analyses of the natural variability of the main photophysiological properties of phytoplankton and their links with the principal abiotic factors in the sea. These analyses have made use of extensive empirical data gathered in a wide diversity of seas and oceans by Polish and Russian teams as well as by joint Polish-Russian expeditions. Data sets available on the Internet have also been applied. As a result, a set of more or less complex, semi-empirical models of light-stimulated processes occurring in marine phytoplankton cells has been developed. The trophic type of sea, photo-acclimation and the production of photoprotecting carotenoids, chromatic acclimation and the production of various forms of chlorophyll-antennas and photosynthetic carotenoids, cell adaptation by the package effect, light absorption, photosynthesis, photoinhibition, the fluorescence effect, and the activation of PS2 centres are all considered in the models. These take into account not only the influence of light, but also, indirectly, that of the vertical mixing of water; in the case of photosynthesis, the quantum yield has been also formulated as being dependent on the nutrient concentrations and the temperature of seawater. The bio-optical spectral models of irradiance transmittance in case 1 oceanic waters and case 2 Baltic waters, developed earlier, also are described in this paper. The development of the models presented here is not yet complete and they all need continual improvement. Nevertheless, we have used them on a preliminary basis for calculating various photosynthetic characteristics at different depths in the sea, such as the concentration of chlorophyll and other pigments, and primary production. The practical algorithm we have constructed allows the vertical distribution of these characteristics to be determined from three input data: chlorophyll a concentration, irradiance, and temperature at the sea surface. Since all three data can be measured remotely, our algorithm can be applied as the "marine part" of the remote sensing algorithms used for detecting marine photosynthesis.

8

Characterization of light absorption coefficient of red Noctiluca scintillans bloom in the South Eastern Arabian Sea

63%

Shaju S. S. , Akula R. R. , Jabir T.

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tom 60

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nr 3

9

Poradnik dla początkującego witrażysty. Malowanie witraża klasycznego. Odcinek 22. Witraż nie musi pochłaniać dużo światła

63%

Bochacz A. , Bochacz A.

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2017

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tom R. 68, nr 5

47

10

Luminescence and photosynthesis of marine phytoplankton - a brief presentation of new results

63%

Wozniak B. , Dera J.

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nr 2

EN

This volume contains a set of eight papers presenting the results of the latest research into the interaction of light with marine phytoplankton by teams from the Marine Physics Department at the IO PAS in Sopot, and the Department of Environmental Physics at the Pedagogical University of Słupsk. These results were presented at the ‘Second Workshop on Luminescence and Photosynthesis of Marine Phytoplankton’ (Sopot–Paraszyno, 11–15 October 1999) sponsored by the Polish State Committee for Scientific Research. This introductory article discusses the most important assumptions and objectives of the research, and outlines the latest results. These are subsequently discussed in detail in the following papers: (1) Majchrowski & Ostrowska, Influence of photo- and chromatic acclimation on pigment composition in the sea, (2) Woźniak et al., Model of the ‘in vivo’ spectral absorption of algal pigments. Part 1. Mathematical apparatus, (3) Majchrowski et al., Model of the ‘in vivo’ spectral absorption of algal pigments. Part 2. Practical applications of the model, (4)Ostrowska et al., Variability of the specific fluorescence of chlorophyll in the ocean. Part 1. Theory of classical ‘in situ’ chlorophyll fluorometry, (5) Ostrowska et al., Variability of the specific fluorescence of chlorophyll in the ocean. Part 2. Fluorometric method of chlorophyll a determination, (6) Ficek et al., Influence of non-photosynthetic pigments on the measured quantum yield of photosynthesis, (7) Ficek et al., Variability of the portion of functional PS2 reaction centres in the light of a fluorometric study. For the reader’s convenience, we append a list of the symbols denoting the physical quantities used in the texts. The nomenclature and denotations are in line with the conventions employed in the subject literature.

11

Inherent optical properties of suspended particulate matter in the Southern Baltic Sea

51%

Wozniak S. B. , Meller J. , Lednicka B. , Zdun A. , Ston-Egiert J.

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nr 3

EN

The inherent optical properties (IOPs) of suspended particulate matter and their relations with the main biogeochemical characteristics of particles have been examined in the surface waters of the southern Baltic Sea. The empirical data were gathered at over 300 stations in open Baltic Sea waters as well as in the coastal waters of the Gulf of Gdańsk. The measurements included IOPs such as the absorption coefficient of particles, absorption coefficient of phytoplankton, scattering and backscattering coefficients of particles, as well as biogeochemical characteristics of suspended matter such as concentrations of suspended particulate matter (SPM), particulate organic matter (POM), particulate organic carbon (POC) and chlorophyll a (Chl a). Our data documented the very extensive variability in the study area of particle concentration measures and IOPs (up to two orders of magnitude). Although most of the particle populations encoun- tered were composed primarily of organic matter (av. POM/SPM=ca 0.8), the different particle concentration ratios suggest that the particle composition varied significantly. The relations between the optical properties and biogeochemical parameters of suspended matter were examined. We found significant variability in the constituent-specific IOPs (coefficients of variation (CVs) of at least 30% to 40%, usually more than 50%). Simple best-fit relations between any given IOP versus any constituent concentration parameter also highlighted the significant statistical errors involved. As a result, we conclude that for southern Baltic samples an easy yet precise quantification of particle IOPs in terms of the concentration of only one of the following parameters – SPM, POM, POC or Chl a – is not achievable. Nevertheless, we present a set of best statistical formulas for a rough estimate of certain seawater constituent concentrations based on relatively easily measurable values of seawater IOPs. These equations can be implemented in practice, but their application will inevitably entail effective statistical errors of estimation of the order of 50% or more.

12

Variability of the specific fluorescence of chlorophyll in the ocean. Part 1. Theory of classical in situ chlorophyll fluorometry

51%

Ostrowska M. , Majchrowski R. , Matorin D. N. , Wozniak B.

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nr 2

EN

The range of variability of the fluorescence properties of marine phytoplankton in different trophic types of seas and at different depths in the sea is analysed theoretically. An attempt is also made to interpret artificially induced in situ fluorescence measured with submersible fluorometers. To do this, earlier optical models of light absorption by phytoplankton (see Woźniak et al. 2000, this volume) and actual empirical data were applied. A straightforward theoretical model of artificially photoinduced phytoplankton fluorescence accounting for the complex influence of different photophysiological characteristics of phytoplankton and the optical characteristics of the instrument has been worked out. A physical method of determining chlorophyll a concentrations in seawater from fluorescence measured in situ with contact fluorometers can be based on this model.