Search results for "Photos"
showing 10 items of 701 documents
Synthesis and antiproliferative mechanism of action of pyrrolo[3′,2′:6,7] cyclohepta[1,2-d]pyrimidin-2-amines as singlet oxygen photosensitizers
2016
A new series of pyrrolo[3′,2′:6,7]cyclohepta[1,2-d]pyrimidin-2-amines, was conveniently prepared using a versatile and high yielding multistep sequence. A good number of derivatives was obtained and the cellular photocytotoxicity was evaluated in vitro against three different human tumor cell lines with EC50 (0.08–4.96 μM) values reaching the nanomolar level. Selected compounds were investigated by laser flash photolysis. The most photocytotoxic derivative, exhibiting a fairly long-lived triplet state (τ ∼ 7 μs) and absorbance in the UV–Vis, was tested in the photo-oxidations of 9,10-anthracenedipropionic acid (ADPA) by singlet oxygen. The photosentizing properties are responsible for the c…
Compensation of Oxygen Transmittance Effects for Proximal Sensing Retrieval of Canopy–Leaving Sun–Induced Chlorophyll Fluorescence
2018
Estimates of Sun–Induced vegetation chlorophyll Fluorescence (SIF) using remote sensing techniques are commonly determined by exploiting solar and/or telluric absorption features. When SIF is retrieved in the strong oxygen (O 2 ) absorption features, atmospheric effects must always be compensated. Whereas correction of atmospheric effects is a standard airborne or satellite data processing step, there is no consensus regarding whether it is required for SIF proximal–sensing measurements nor what is the best strategy to be followed. Thus, by using simulated data, this work provides a comprehensive analysis about how atmospheric effects impact SIF estimations on proximal sensing, regarding: (…
Satellite Observations of the Contrasting Response of Trees and Grasses to Variations in Water Availability
2019
Interannual variations in ecosystem primary productivity are dominated by water availability. Until recently, characterizing the photosynthetic response of different ecosystems to soil moisture anomalies was hampered by observational limitations. Here, we use a number of satellite-based proxies for productivity, including spectral indices, sun-induced chlorophyll fluorescence, and data-driven estimates of gross primary production, to reevaluate the relationship between terrestrial photosynthesis and water. In contrast to nonwoody vegetation, we find a resilience of forested ecosystems to reduced soil moisture. Sun-induced chlorophyll fluorescence and data-driven gross primary production ind…
Culture Conditions Affect Antioxidant Production, Metabolism and Related Biomarkers of the Microalgae Phaeodactylum tricornutum
2022
Phaeodactylum tricornutum (Bacillariophyta) is a worldwide-distributed diatom with the ability to adapt and survive in different environmental habitats and nutrient-limited conditions. In this research, we investigated the growth performance, the total lipids productivity, the major categories of fatty acids, and the antioxidant content in P. tricornutum subjected for 15 days to nitrogen deprivation (N−) compared to standard culture conditions (N+). Furthermore, genes and pathways related to lipid biosynthesis (i.e., glucose-6-phosphate dehydrogenase, acetyl-coenzyme A carboxylase, citrate synthase, and isocitrate dehydrogenase) and photosynthetic activity (i.e., ribulose-1,5-bisphosp…
Integration of 3D modelling with photogrammetry applied on historical images for cultural heritage
2023
The recovery of past architecture through 3D modelling is an important challenge today to the preservation of heritage. Decisive support for the interpretation of architecture can certainly come from historical images and old photographs that fix a portion of space at a specific time, keeping it unchanged over the years. This acquisition is decisive for studying architectures of the past that can be reinterpreted and analysed. Photos, in fact, capture the advance of time and the life of a building at a precise historical moment, becoming essential documents for the study and knowledge of heritage. An additional advantage is when these old images can be processed through Structure for Motion…
New tricyclic systems as photosensitizers towards triple negative breast cancer cells.
2022
AbstractNineteen pyrrolo[1,2-h][1,7]naphthyridinones and pyrido[2,3-c]pyrrolo[1,2-a]azepinones were synthesized as new tricyclic systems in which the pyridine ring is annelated to the 6,7-dihydroindolizin-8(5H)-one and 5,6,7,8-tetrahydro-9H-pyrrole[1,2-a]azepine-9-one moieties to obtain potential photosensitizing agents. They were tested for their photoantiproliferative activity on a triple-negative breast cancer cell line, MDA-MB-231, in the dark and under UVA light (2.0 J/cm2). We demonstrated that their toxicity, only when exposed to light, was primarily due to the generation of reactive oxygen species while their photodegradation products were not responsible for their activity. The mos…
Mannitol-producing tobacco exposed to varying levels of water, light, temperature and paraquat
2007
Transgenic mannitol-producing (+mtlD) and wild-type (-mtlD) tobacco plants were exposed to water deficit, varying light intensities, low temperatures, and paraquat applications to test whether mannitol was involved in protection against abiotic stresses. In the water deficit experiment, -mtlD and +mtlD plants were fully irrigated [100% evapotranspiration (ET)] or received 25% ET for 40 d. Water deficit reduced the relative water content (RWC) of both types of plant starting on day 22 and the total stem length (TSL) of -mtlD 25% ET plants after 11 d, whereas TSL of +mtlD 25% ET was reduced only after 34 d. After 30 days of water deficit, a higher percentage of mature foliage was retained by …
The N-terminal domain of the light-harvesting chlorophyll a/b-binding protein complex (LHCII) is essential for its acclimative proteolysis.
2000
AbstractVariations in the amount of the light-harvesting chlorophyll a/b-binding protein complex (LHCII) is essential for regulation of the uptake of light into photosystem II. An endogenous proteolytic system was found to be involved in the degradation of LHCII in response to elevated light intensities and the proteolysis was shown to be under tight regulation [Yang, D.-H. et al. (1998) Plant Physiol. 118, 827–834]. In this study, the substrate specificity and recognition site towards the protease were examined using reconstituted wild-type and mutant recombinant LHCII. The results show that the LHCII apoprotein and the monomeric form of the holoprotein are targeted for proteolysis while t…
A broader model for C 4 photosynthesis evolution in plants inferred from the goosefoot family (Chenopodiaceae s.s.)
2012
C 4 photosynthesis is a fascinating example of parallel evolution of a complex trait involving multiple genetic, biochemical and anatomical changes. It is seen as an adaptation to deleteriously high levels of photorespiration. The current scenario for C 4 evolution inferred from grasses is that it originated subsequent to the Oligocene decline in CO 2 levels, is promoted in open habitats, acts as a pre-adaptation to drought resistance, and, once gained, is not subsequently lost. We test the generality of these hypotheses using a dated phylogeny of Amaranthaceae s.l. (including Chenopodiaceae), which includes the largest number of C 4 lineages in eudicots. The oldest chenopod C 4 lineage da…
UV variability and accretion dynamics in the young open cluster NGC 2264
2015
We explore UV and optical variability signatures for several hundred members of NGC 2264 (3 Myr). We performed simultaneous u- and r-band monitoring over two full weeks with CFHT/MegaCam. About 750 young stars are probed; 40% of them are accreting. Statistically distinct variability properties are observed for accreting and non-accreting cluster members. The accretors exhibit a significantly higher level of variability than the non-accretors, especially in the UV. The amount of u-band variability correlates statistically with UV excess in disk-bearing objects, which suggests that accretion and star-disk interaction are the main sources of variability. Cool magnetic spots, several hundred de…