Search results for "Photos"
showing 10 items of 701 documents
Mössbauer Spectroscopy on Photosynthetic Bacteria: Investigation of Reaction Centers of Rhodopseudomonas Viridis
1990
Crystals of 57Fe enriched reaction centers have been investigated by Mossbauer spectroscopy. The cytochrome irons are in the low spin ferric state. The non-heme iron of the electron accepting side is partly ferrous high spin and partly ferrous low spin (or ferric high spin). Under the conditions of the experiment sodium ascorbate reduces only one cytochrome iron into the ferrous low spin state. Membrane bound proteins become flexible at higher temperatures than proteins with a hydrophilic surface. They are also less flexible, at least up to temperatures of about 250 K.
Fast Photochemistry of Prototypical Phytochromes : A Species vs. Subunit Specific Comparison
2015
Phytochromes are multi-domain red light photosensor proteins, which convert red light photons to biological activity utilizing the multitude of structural and chemical reactions. The steady increase in structural information obtained from various bacteriophytochromes has increased understanding about the functional mechanism of the photochemical processes of the phytochromes. Furthermore, a number of spectroscopic studies have revealed kinetic information about the light-induced reactions. The spectroscopic changes are, however, challenging to connect with the structural changes of the chromophore and the protein environment, as the excited state properties of the chromophores are very sens…
Documenting the light sensitivity of Spanish Levantine rock art paintings
2015
[EN] A case study to evaluate the use of microfading spectrometry (MFS) for the study of colored systems found in prehistoric rock art paintings was conducted in the Cova Remígia rock-shelter, Castellón (Spain). This rock shelter is part of the rock art sites of the Mediterranean basin on the Iberian Peninsula included in UNESCO s World Heritage List. Some of the paintings belonging to this group are exposed to environmental factors including natural daylight, wind and rain, depending on the time of the day and the season of the year. Therefore, their preservation is a major concern to stakeholders and researchers responsible for protecting and studying these prehistoric paintings. The expe…
Design, Synthesis and Characterization of a Visible-Light-Sensitive Molecular Switch and Its PEGylation Towards a Self-Assembling Molecule.
2022
HBDI-like chromophores represent a novel set of biomimetic switches mimicking the fluorophore of the green fluorescent protein that are currently studied with the hope to expand the molecular switch/motor toolbox. However, until now members capable of absorbing visible light in their neutral (i. e. non-anionic) form have not been reported. In this contribution we report the preparation of an HBDI-like chromophore based on a 3-phenylbenzofulvene scaffold capable of absorbing blue light and photoisomerizing on the picosecond timescale. More specifically, we show that double-bond photoisomerization occurs in both the E-to-Z and Z-to-E directions and that these can be controlled by irradiating …
Metabolic plasticity of mixotrophic algae is key for their persistence in browning environments
2022
Light availability is the main regulator of primary production, shaping photosynthetic communities and their production of ecologically important biomolecules. In freshwater ecosystems, increasing dissolved organic carbon concentrations, commonly known as browning, leads to lower light availability and the proliferation of mixotrophic phytoplankton. Here, a mixotrophic algal species (Cryptomonas sp.) was grown under five increasing dissolved organic carbon concentrations to uncover the plastic responses behind the success of mixotrophs in browning environments and their effect in the availability of nutritionally important biomolecules. In addition to the browning treatments, phototrophic, …
Macroalgal responses to ocean acidification depend on nutrient and light levels
2015
Ocean acidification may benefit algae that are able to capitalize on increased carbon availability for photosynthesis, but it is expected to have adverse effects on calcified algae through dissolution. Shifts in dominance between primary producers will have knock-on effects on marine ecosystems and will likely vary regionally, depending on factors such as irradiance (light vs. shade) and nutrient levels (oligotrophic vs. eutrophic). Thus experiments are needed to evaluate interactive effects of combined stressors in the field. In this study, we investigated the physiological responses of macroalgae near a CO2 seep in oligotrophic waters off Vulcano (Italy). The algae were incubated in situ …
Data from: A revision of Sesuvium (Aizoaceae, Sesuvioideae)
2017
Sesuvium and Cypselea are closely related succulent genera within the Sesuvioideae (Aizoaceae). Since Cypselea is nested in Sesuvium in molecular studies and both genera share traits separating them from other members of the subfamily, we propose to include Cypselea in Sesuvium. Sesuvium (incl. Cypselea) comprises 14 species and is distributed worldwide with centres of diversity in southern Africa and North and Central America. Sesuvium comprises erect to procumbent herbs with opposite leaves that often bear conspicuous sheath-like lateral appendages on the petioles (pseudostipules). These and the many-seeded capsules are diagnostic traits, separating Sesuvium from the closely related gener…
Projection and Pinhole-Based Data Acquisition for Small-Animal SPECT Using Storage Phosphor Technology
2007
Three-dimensional Single Photon Emission Computed Tomography (SPECT) can provide high-resolution insight into biomolecular distribution and pharmacokinetics. However, instrument availability and distribution is limited at present,and imaging times can be considerable. To evaluate the large array of novel agents which are becoming available,we find that storage phosphor-based in vivo imaging can provide an important,rapid-throughput transition from the traditional ex vivo sacrifice/gamma counting and autoradiography to full-time course SPECT.
Differences in visual information processing style between Idiopathic Generalized Epilepsy with and without photosensitivity.
2021
Purpose: Recently, altered visual cortical processes i.e., lack of habituation to visual evoked potentials (VEP), has been highlighted in both photosensitive epilepsy and in a specific i.e., analytic mode of processing visual inputs. In this study we aimed at evaluating the relationship between photosensitivity (PS) and analytic style of processing visual information, in a sample of 30 patients with Idiopathic Generalized Epilepsy (IGE) and matched healthy controls. Methods: At our Epilepsy unit of the Sapienza University of Rome, we consecutively enrolled 15 patients with IGE with PSand matched them with 15 patients with IGE without PS and 15 Healthy Volunteers. All patients underwent EEG …
Feasibility and Diagnostic Impact of Fluorescence-Based Diagnostic Laparoscopy in Hepatocellular Carcinoma: A Case Report
2002
Fluorescence-based diagnostic techniques are an evolving field in the staging of hepatologic and gastroenterologic malignancies. The method aims at improved accuracy in the detection of locoregional and distant metastases. In hepatocellular carcinoma, detection of metastases is of utmost importance, because advanced tumors preclude curative surgical therapy. We present here our first experience of fluorescence-based diagnostic laparoscopy in a patient with hepatocellular carcinoma. We performed diagnostic laparoscopy in a 76-year-old woman who presented with a tumor of the liver and increased serum levels of alpha-fetoprotein. For photosensitization, 5-aminolevulinic acid (20 mg/kg bodyweig…