Letteratura scientifica selezionata sul tema "Ex situ illumination"

The article discusses morpho-functional features of 25 species of woody subtropical plants (Acca sellowiana (O.Berg) Burret, Myrtus communis L., Murraya paniculata (L.) Jack , Coussapoa microcarpa (Schott) Rizzini, Cascabela thevetia (L.) Lippold, Podocarpus macrophyllus (Thunb.) Sweet, Podocarpus salicifolius Klotzsch & H.Karst. ex Endl., Phyllanthus juglandifolius Willd., Nandina domestica Thunb., Asparagus falcatus L., Ficus pumila L., Ficus cyathistipula Warb., Ficus binnendijkii Miq., Ficus retusa L., Ficus sagittata Vahl, Cinnamomum camphora (L.) J.Presl, Laurus nobilis L., Olea europaea L., Ligustrum japonicum Thunb., Ceratonia siliqua L., Tamarindus indica L., Pittosporum tobira (Thunb.) W.T.Aiton, Camellia japonica L., Magnolia obovata Thunb., Hibiscus sinensis Mill.) growing in the greenhouse of the Botanical Garden of Samara University. To assess the adaptability of the species, the following parameters are used: the reflectivity of the leaves (upper and lower sides), the thickness of the leaf blade, the specific area of the leaves (SLA), the content of caratinoids and chlorophylls (a, b). The collection of leaf material was carried out during two growing seasons. The analysis of the parameters takes into account climatic factors, such as average monthly temperatures, air humidity, illumination. In the species studied by us, the values of the specific leaf area index range from 58 to 363 sq.cm / g, the thickness of the leaf blade from 100 to 305 microns. During the analysis, a correlation (average conjugacy) was established for the studied species the thickness of the leaf blade with the reflection of the leaf blade (R=0.65) and the content of photosynthetic pigments hl.a (R= -0.79) and carotenoids (R= -0.59), illumination (R=0.43).

Asplenium adulterinum Milde represents one of the natural heritages which have to be protected due to their scientific importance. In the actual context of global warming with myriad effects on biodiversity, the ex-situ conservation of A. adulterinum should be a priority. The possibility to obtain genetically stable individuals through in vitro techniques is a requirement of ex situ conservation. The genetic similarity of A. adulterinum gametophytes maintained 8 years in vitro culture was assessed. Explants represented by gametophyte fragments were analyzed for genetic stability through RAPD. Close similarity (88.88%) was found between gametophytes maintained in the same conditions (medium, illumination, temperature, passages number). Bangladesh J. Bot. 51(2): 387-391, 2022 (June)

This study was aimed to prepare material with high porosity and photocatalytic activity by immobilization of TiO2 nanoparticles (NPs) onto poly(lactic acid) (PLA) aerogels. PLA aerogels were prepared in three steps: (1) dissolution of polymer in chloroform at 22 °C, (2) chloroform replacement with ethanol, and (3) supercritical CO2-drying at pressure 19 MPa and temperature 39 ºC. Immobilization of TiO2 NPs was performed by in situ and ex situ methods. Obtained samples were characterized using SEM, EDX, and FTIR analysis. Photocatalytic activity of developed material was tested by following decolorization of dye C.I. Acid Orange 7 in water solution. It was shown that the morphology of PLA aerogels was slightly affected by TiO2 NPs immobilization. PLA aerogels with TiO2 NPs immobilized by ex situ method sustained floatability during test period and provided a complete decolorization of dye solution after 330 minutes of illumination. High photocatalytic activity of the sample was preserved within three repeated cycles of dye decolorization.

New technologies of reintroduction of plant species presuppose implementing both traditional and biotechnological methods for obtaining certain planting materials. However, plants cultivated in vitro exist in specific conditions that lead to changes in their structural and functional state. This explains why it is hard for them to adapt to ex vitro and in situ conditions. Therefore, there is a need for the development of a multistage method of cultivating in vitro plants that would make the influence on their adaptive mechanism in ex vitro and in situ conditions possible. One of its stages is the optimization of the light regime of cultivation which can both initiate the change of the state of the photosynthetic apparatus of plants and increase their bioproductivity stimulating the work of their protective system. This work studies changes in the morphogenesis, growth data and pigment composition of the rare species of Gentiana lutea L. of three populations in the Ukrainian Carpathian (mountains Pozhyzhevska and Sheshul-Pavlyk, plateau Lemska) in vitro focusing particularly on the cultivation light regime. The research has proved the inefficiency of using fluorescent lamps of daylight lamps (LD) type as source of illumination because the low intensity of luminous flux in the area of photosynthetically active radiation (PAR), as well as high proportion of wavelength of blue (400–500 nm) and green (500–600 nm) range in the spectrum cause specific reactions of photomorphogenesis, which, despite the high content of pigments in plastids, lead to poor development of root systems, stretching the stems, formation of small leaves with thin leaflet plate, generally low productivity and low adaptive potential of G. lutea plants to ex vitro and in situ conditions. Complement of cold white light lamps to the fluorescent lamps LD type in the ratio of 1 : 1 enables one to increase the intensity of illumination in the field of PAR and raise the fraction of wavelength of red range (600–700 nm). Such light conditions both improve the bio-productivity of G. lutea plants of all three populations cultured in vitro in comparison to the LD type regimen, reducing the content of chlorophyll b and carotenoids in light-harvesting complexes of photosystems and facilitate an increase in the microclonal multiplication factor without using higher concentrations of exogenous growth regulators,which significantly reduces the cost of the process of obtaining planting materials. It was proved that a combination of LD type lamps, cold white light lamps and phytolamps in the ratio 1 : 1 : 0.6 should be used on the final stages of preparation of the planting material of G. lutea before transferring it to ex vitro and in situ conditions. This relates to the fact that the increase of the wavelength of the red range results in the widening of the active surface of the leaves, rise in the content of photosynthetic pigments, and the noticeable growth of the aboveground and underground parts of the plants. The article assumes that the use of such illumination mode will ensure a faster transition of cultured in vitro G. lutea plants from heterotrophic to autotrophic nutrition, improving their adaptive potential and enabling easier adaptation to non-sterile ex vitro and in situ conditions.

β-Ga2O3 thin films were grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The films were grown using an elemental gallium source and oxygen supplied by an RF plasma source. Reflection high-energy electron diffraction (RHEED) was used to monitor the surface quality in real time. Both in situ RHEED and ex situ X-ray diffraction confirmed the formation of single crystal β-phase films with excellent crystallinity on c-plane sapphire. Spectroscopic ellipsometry was used to determine the film thicknesses, giving values in the 11.6–18.8 nm range and the refractive index dispersion curves. UV-Vis transmittance measurements revealed that strong absorption of β-Ga2O3 starts at ∼270 nm. Top metal contacts were deposited by thermal evaporation for I-V characterization, which has been carried out in dark, as well as under visible and UV light illumination. The optical and electrical measurements showed that the grown thin films of β-Ga2O3 are excellent candidates for deep-ultraviolet detection and sensing.

Summary Ophrys sphegodes Mill. is a wild orchid species which is threatened and protected due to its pollination biology, small seed and habitat destruction. The aim of this study was to establish asymbiotic germination protocol for the purpose of ex situ conservation. Two basal media Knudson C (KC) and Malmgren (MM), supplemented with organic additives (peptone (PE), L-glutamin (A)e, folic acid, casein hydrolysate (CA)) added separately and control media KC--C and MM--C were used in the present research. All the nutrition media contained 2% sucrose, 7% agar and 1% activated carbon, while their pH was adjusted to 5.8 ± 0.02 before autoclaving at 121 ° C for 20 minutes. The seeds were examined under two illumination conditions, 0/24 light/dark (L/D) and 16/8 L/D. The presented results indicate a huge influence of illumination and nutrition media on the seed germination and protocorm formation. The seed germination was overall significantly more successful in dark conditions (0/24 L/D) than with lighting (16/8 L/D). Protocorm, rhizoids and shoot formation were achieved only on the seeds cultured on MM medium, while the KC medium caused only swelling of the embryo. Organic additives had positive influence on the germination rate. According to the obtained results, the best germination rate and seedling development were achieved on MM-PE media, cultured in dark. The presented procedure accelerates the germination period and can provide a large number of plants in a relatively short period of time so it can be used for conservation programs and mass production protocol.

Abstract: The role of phototrophs is examined in alternative energy, with the main emphasis on unicellular algae. Particular attention is paid to the use of phototrophs for generating electricity using biofuel cells (plant and enzymatic biofuel cells are discussed). This study focuses on microbial fuel cells (MFC), which, along with electric power, allow obtaining biofuels and biohydrogen. This article explains the factors limiting the MFC power, and ways of overcoming them. For example, it seems promising to develop various photobioreactors in order to reduce the loss of MFC power due to overvoltage. The use of microphototrophs in MFC has led to the development of photosynthetic MFC (or PhotoMFC) through the design of autotrophic photobioreactors with forced illumination. They allow generating oxygen through photosynthesis, both in situ and ex situ, by recirculating oxygen from the photobioreactor to the cathode chamber. Artificial redox mediators can be used here, transferring electrons directly from the non-catalytic cathode to O2, formed as a result of the photosynthetic activity of algae. Biologically catalyzed cathodes have been proven to generate less power than chemical catalysts. It is noted, that the MFC installations with the micro-algae allow utilizing a wider circle of different connections – the components of effluents and withdrawals: organic acids, sugar, alcohols, fats and other substrata. The use of phototrophs for the production of biofuels is of special interest. Several different types of renewable biofuels can be produced from microalgae, the production of which can be combined with wastewater treatment, CO2 capture and production of various compounds.

ABSRTACTIn this article, we report low-temperature electron spin resonance (ESR) investigations carried out on solution processed three-layer inverted solar cell structures: PC61BM/CH3NH3PbI3/PEDOT:PSS/Glass, where PC61BM and PEDOT:PSS act as electron and hole transport layers, respectively. ESR measurements were conducted on ex-situ light (1 Sun) illuminated samples. We find two distinct ESR spectra. First ESR spectra resembles a typical powder pattern, associated with gx = gy = 4.2; gz = 9.2, found to be originated from Fe3+ extrinsic impurity located in the glass substrate. Second ESR spectra contains a broad (peak-to-peak line width ∼ 10 G) and intense ESR signal appearing at g = 2.008; and a weak, partly overlapped, but much narrower (peak-to-peak line width ∼ 4 G) ESR signal at g = 2.0022. Both sets of ESR spectra degrade in intensity upon light illumination. The latter two signals were found to stem from light-induced silicon dangling bonds and oxygen vacancies, respectively. Our controlled measurements confirm that these centers were generated during UV-ozone treatment of the glass substrate –a necessary step to be performed before PEDOT:PSS is spin coated. This work forms a significant step in understanding the light-induced- as well as extrinsic defects in perovskite solar cell materials.

Abstract An alternative method for the fast evaluation of transient liquid crystal experiments is presented in this study. The calibration of liquid crystals has been considered essential to obtain accurate heat transfer measurements. Nevertheless, liquid crystal aging, illumination, and ex situ calibration effects remain a difficult and might influence the heat transfer level. Proposed here is to bypass liquid crystal calibration by utilizing the evolution of the wall temperature gradients. This necessitates the use of the detection times of the maximum red and green intensities of narrow bandwidth liquid crystals, e.g., less than 1 K, whose temperature span is on the order of 0.3 K. The calculation of the heat transfer coefficients can be thus feasible by differentiating the wall temperature from the solution of the semi-infinite body approach with respect to time. This approach is examined over different experiments with varying geometries and liquid crystal detection times. The in-advance possession of the calibration curves of the liquid crystals allows for the method’s cross-evaluation. The results indicate that the proposed method is in sufficiently good agreement with the values obtained using the calibrated liquid crystal signals. In particular, the average heat transfer coefficient of a surface is within 8% from the traditional method which is sufficient for industrial applications and preliminary thermal designs.

In the present work, an insight on the morpho/structural properties of semitransparent organic devices for buildings’ integrated photovoltaics is presented, and issues related to interface and bulk stability are addressed. The organic photovoltaic (OPV) cells under investigation are characterized by a blend of PM6:Y6 as a photo-active layer, a ZnO ETL (electron transporting layer), a HTL (hole transporting layer) of HTL-X and a transparent electrode composed by Ag nanowires (AgNWs). The devices’ active nanomaterials, processed as thin films, and their mutual nanoscale interfaces are investigated by a combination of in situ Energy Dispersive X-ray Reflectometry (EDXR) and ex situ Atomic Force Microscopy (AFM), X-ray Diffraction (XRD) and micro-Raman spectroscopy. In order to discriminate among diverse concomitant aging pathways potentially occurring upon working conditions, the effects of different stress factors were investigated: light and temperature. Evidence is gained of an essential structural stability, although an increased roughness at the ZnO/PM6:Y6 interface is deduced by EDXR measurements. On the contrary, an overall stability of the system subjected to thermal stress in the dark was observed, which is a clear indication of the photo-induced origin of the observed degradation phenomenon. Micro-Raman spectroscopy brings light on the origin of such effect, evidencing a photo-oxidation process of the active material in the device, using hygroscopic organic HTL, during continuous illumination in ambient moisture conditions. The process may be also triggered by a photocatalytic role of the ZnO layer. Therefore, an alternative configuration is proposed, where the hygroscopic HTL-X is replaced by the inorganic compound MoOx. The results show that such alternative configuration is stable under light stress (solar simulator), suggesting that the use of Molybdenum Oxide, limiting the photo-oxidation of the bulk PM6:Y6 active material, can prevent the cell from degradation.

Les recherches présentées dans ce manuscrit de thèse se divisent en deux parties. Dans la première partie, nous avons étudié la dégradation photocatalysée du N-méthoxy-N-(triméthylsilylméthyl)benzaldéhyde en présence de rose bengale dans l’acétonitrile. Les expériences de RMN 1D, la RMN 1H photo-CIDNP, ainsi que les analyses 2D 1H-13C HSQC et HMBC, combinées à une illumination in situ et ex situ, ont permis d'élucider la structure de plusieurs intermédiaires et produits formés durant cette réaction. L'illumination ex situ, réalisée à l'aide d'un système de flux continu, a été particulièrement utile pour compléter les résultats obtenus in situ et pour établir des comparaisons avec ceux obtenus par synthèse, soulignant ainsi l'importance de l'illumination ex situ dans l'étude des réactions en photochimie. Par ailleurs, les expériences de RMN 1H photo-CIDNP ont clairement démontré que la dégradation de l'éther de l’hémiaminal en présence de rose bengale passe par la formation d'un radical cation, sans engendrer de formation de 1,3-dipôle.Dans la seconde partie, nous nous sommes intéressés à la mécanistique de la réaction d’alkylation photo-induite via un complexe EDA (sel de Katritzky/DIPEA), en utilisant la RMN couplée à l’illumination in situ. Grâce aux expériences de RMN 1H photo-CIDNP, nous avons mis en évidence la présence de deux complexes EDA distincts dans le milieu réactionnel : un complexe 1:1 et un complexe 1:2 (sel de Katritzky : DIPEA), absorbant respectivement à λ = 450 nm et à λ = 520 nm. Les études de RMN 1D 1H et 1H photo-CIDNP ont révélé l'absence de diffusion du groupe partant du sel de Katritzky, prouvant ainsi que la réaction d’alkylation s'effectue dans la sphère de solvatation du complexe EDA. Ces observations, combinées aux données extraites des expériences de RMN 1H DOSY, ont permis d'identifier la nature des agrégats (complexe EDA/substrat) impliqués dans la réactivité aux deux longueurs d'onde, démontrant clairement le lien étroit entre la proportion de ces agrégats dans le milieu réactionnel et le rendement de la réaction d’alkylation photo-induite
The research presented in this thesis manuscript is organized into two main sections. The first section investigates the photocatalytic degradation of N-methoxy-N-(trimethylsilylmethyl)benzaldehyde in the presence of rose Bengal in acetonitrile. We utilized various techniques, including 1D NMR experiments, 1H photo-CIDNP, and 2D 1H-13C HSQC and HMBC analyses, alongside both in situ and ex situ illumination. These methods enabled us to elucidate the structures of several intermediates and products formed during the reaction. Notably, ex situ illumination, executed through a continuous flow system, proved particularly beneficial for complementing our in situ results and making comparisons with synthesized products, underscoring the significant role of ex situ illumination in the study of photochemical reactions. Moreover, the 1H photo-CIDNP experiments clearly indicated that the degradation of the hemiaminal ether in the presence of rose Bengal occurs via the formation of a cation radical, without the generation of any 1,3-dipole intermediates.In the second section, we shifted our focus to the mechanism of the photo-induced alkylation reaction via an EDA complex (Katritzky salt/DIPEA), employing NMR in conjunction with in situ illumination. 1H photo-CIDNP experiments revealed the presence of two distinct EDA complexes in the reaction medium: a 1:1 complex and a 1:2 complex (Katritzky salt: DIPEA), which absorb at λ = 450 nm and λ = 520 nm, respectively. Additional 1D 1H NMR and 1H photo-CIDNP studies demonstrated the absence of leaving group diffusion from the Katritzky salt, confirming that the alkylation reaction occurs within the solvation sphere of the EDA complex. These findings, along with data obtained from 1H DOSY NMR experiments, allowed us to ascertain the nature of the aggregates (EDA complex/substrate) participating in reactivity at both wavelengths. This clearly illustrates the close relationship between the proportion of these aggregates in the reaction medium and the yield of the photo-induced alkylation reaction

This chapter examines the rise and development of calypso in Trinidad. Trinidad is a rich site to explore issues of diaspora and historical development in the Caribbean since the island has the dubious distinction of being subject to all the major imperial powers in the region. Calypso is quintessentially urban, developed in the late 19^th century through the intermingling of the largely once-rural proletariat, unemployed and under-employed ex-slaves, and formerly indentured Africans and other Creoles in the burgeoning city of Port-of-Spain. The music emerged from and was developed in the barrack yards, stick-fights, carnival tents, and city streets, and became a national music and symbol. This period is also one in which the economic penetration of the British into the island was transformed into formal political and ideological control, thus illuminating inter-imperialist rivalries and transformations, and the complications of political transition in a “plural society.”