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https://www.readbyqxmd.com/read/28937283/engineering-rubisco-activase-from-thermophilic-cyanobacteria-into-high-temperature-sensitive-plants
#1
Chukwuma C Ogbaga, Piotr Stepien, Habib-Ur-Rehman Athar, Muhammad Ashraf
In the past decade, various strategies to improve photosynthesis and crop yield, such as leaf morphology, light interception and use efficiency, biochemistry of light reactions, stomatal conductance, carboxylation efficiency, and source to sink regulation, have been discussed at length. Leaf morphology and physiology are tightly coupled to light capturing efficiency, gas exchange capacity, and temperature regulation. However, apart from the photoprotective mechanism of photosystem-II (PSII), i.e. non-photochemical quenching, very low genetic variation in the components of light reactions has been observed in plants...
September 22, 2017: Critical Reviews in Biotechnology
https://www.readbyqxmd.com/read/28937170/photochemistry-and-aggregation-behavior-of-triethylene-glycol-teg-terminated-stilbene-dendrimers
#2
Hiroya Sakurai, Takashi Maruyama, Tatsuo Arai
The photochemical properties of stilbene cored amphiphilic dendrimers (G0-G3) in THF and water were investigated. The solvation dynamics in water depended on the generation, while the behavior is almost the same in THF. Dendrimers G1 and G2 form molecular assemblies and undergo photodimerization reaction in addition to photoisomerization. G3 has enough TEG groups on the surface to cover the hydrophobic moiety within a single molecule. These dendrimers have free space around the core to undergo mutual isomerization even in water...
September 22, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28936501/photochemical-generation-and-trapping-of-3-oxacyclohexyne
#3
Rui Fan, Yuewei Wen, Dasan M Thamattoor
The strained heterocyclic alkyne, 3-oxacyclohexyne, was generated photochemically for the first time using a cyclopropanated phenanthrene precursor, and trapped by cyclopentadienones as Diels-Alder adducts. The precursor initially produced the putative 3-oxacyclopentylidenecarbene that subsequently rearranged to the cycloalkyne. Computational studies indicate that the carbene favors a singlet state, and the barrier for its ring expansion by a 1,2-shift of the carbon proximal to oxygen is lower in energy than the corresponding shift of the distal carbon...
September 22, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28936338/photochemically-active-dna-intercalating-ruthenium-and-related-complexes-insights-by-combining-crystallography-and-transient-spectroscopy
#4
Christine J Cardin, John M Kelly, Susan J Quinn
Recent research on the study of the interaction of ruthenium polypyridyl compounds and defined sequence nucleic acids is reviewed. Particular emphasis is paid to complexes [Ru(LL)2(Int)](2+) containing potentially intercalating ligands (Int) such as dipyridophenazine (dppz), which are known to display light-switching or photo-oxidising behaviour, depending on the nature of the ancillary ligands. X-ray crystallography has made a key contribution to our understanding, and the first complete survey of structural results is presented...
July 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28935961/field-cycling-nmr-with-high-resolution-detection-under-magic-angle-spinning-determination-of-field-window-for-nuclear-hyperpolarization-in-a-photosynthetic-reaction-center
#5
Daniel Gräsing, Pavlo Bielytskyi, Isaac F Céspedes-Camacho, A Alia, Thorsten Marquardsen, Frank Engelke, Jörg Matysik
Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect...
September 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28931794/health-effects-of-air-pollution-a-historical-review-and-present-status
#6
Masayuki Shima
During the 1960s, the concentrations of air pollutants, particularly that of sulfur dioxide (SO2), were extremely high in many industrial cities in Japan, and the prevalence of bronchial asthma and chronic bronchitis increased among residents living in the cities. To evaluate the effects of air pollution on respiratory diseases, many epidemiological studies were conducted, and the findings played an important role in the regulatory control of air pollution. After 1970, the concentration of SO2 has decreased markedly, and its adverse health effects have been minimized...
2017: Nihon Eiseigaku Zasshi. Japanese Journal of Hygiene
https://www.readbyqxmd.com/read/28930435/new-triplet-sensitization-routes-for-photon-upconversion-thermally-activated-delayed-fluorescence-molecules-inorganic-nanocrystals-and-singlet-to-triplet-absorption
#7
Nobuhiro Yanai, Nobuo Kimizuka
Photon upconversion based on triplet-triplet annihilation (TTA-UC) has attracted much interest because of its possible applications to renewable energy production and biological fields. In particular, the UC of near-infrared (NIR) light to visible (vis) light is imperative to overcome the Shockley-Queisser limit of single-junction photovoltaic cells, and the efficiency of photocatalytic hydrogen production from water can also be improved with the aid of vis-to-ultraviolet (UV) UC. However, both processes have met limitations in the wavelength range, efficiency, and sensitivity for weak incident light...
September 20, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28928466/magnetic-field-effect-in-natural-cryptochrome-explored-with-model-compound
#8
Shubhajit Paul, Alexey S Kiryutin, Jinping Guo, Konstantin L Ivanov, Jörg Matysik, Alexandra V Yurkovskaya, Xiaojie Wang
Many animals sense the Earth's magnetic-field and use it for navigation. It is proposed that a light-dependent quantum effect in cryptochrome proteins, residing in the retina, allows for such an iron-free spin-chemical compass. The photochemical processes, spin-dynamics and its magnetic field dependence in natural cryptochrome are not fully understood by the in vivo and in vitro studies. For a deeper insight into these biophysical mechanisms in cryptochrome, we had introduced a flavin-tryptophan dyad (F10T)...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28927266/resolving-the-notorious-case-of-conical-intersections-for-coupled-cluster-dynamics
#9
Eirik F Kjønstad, Henrik Koch
The motion of electrons and nuclei in photochemical events often involve conical intersections, degeneracies between electronic states. They serve as funnels in nuclear relaxation processes where the electrons and nuclei couple nonadiabatically. Accurate ab initio quantum chemical models are essential for interpreting experimental measurements of such phenomena. In this Letter we resolve a long-standing problem in coupled cluster theory, presenting the first formulation of the theory that correctly describes conical intersections between excited electronic states of the same symmetry...
September 19, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28926960/genetic-and-hormonal-regulation-of-chlorophyll-degradation-during-maturation-of-seeds-with-green-embryos
#10
REVIEW
Galina Smolikova, Elena Dolgikh, Maria Vikhnina, Andrej Frolov, Sergei Medvedev
The embryos of some angiosperms (usually referred to as chloroembryos) contain chlorophylls during the whole period of embryogenesis. Developing embryos have photochemically active chloroplasts and are able to produce assimilates, further converted in reserve biopolymers, whereas at the late steps of embryogenesis, seeds undergo dehydration, degradation of chlorophylls, transformation of chloroplast in storage plastids, and enter the dormancy period. However, in some seeds, the process of chlorophyll degradation remains incomplete...
September 16, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28926259/dual-photochemical-reaction-pathway-in-flavin-based-photoreceptor-lov-domain-a-combined-quantum-mechanics-molecular-mechanics-investigation
#11
Setsuko Nakagawa, Oliver Weingart, Christel M Marian
The primary photochemical reaction of the light, oxygen, and voltage (LOV) domain of the blue-light photo-sensor YtvA of Bacillus subtilis were investigated using high-level QM(DFT/MRCI)/MM methods. After blue-light excitation, the Sγ atom of the reactive cysteine forms a covalent bond with the C4a of the flavin mononucleotide (FMN) ring. Two conformations for the side chain of reactive cysteine with occupancies of 70% (conf A) and 30% (conf B) are observed in the X-ray crystallographic structures of the YtvA-LOV (Möglich, A...
September 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28924898/formation-of-tyrosine-radicals-in-photosystem-ii-under-far-red-illumination
#12
Nigar Ahmadova, Fikret Mamedov
Photosystem II (PS II) contains two redox-active tyrosine residues on the donor side at symmetrical positions to the primary donor, P680. TyrZ, part of the water-oxidizing complex, is a preferential fast electron donor while TyrD is a slow auxiliary donor to P680(+). We used PS II membranes from spinach which were depleted of the water oxidation complex (Mn-depleted PS II) to study electron donation from both tyrosines by time-resolved EPR spectroscopy under visible and far-red continuous light and laser flash illumination...
September 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28924017/in-silico-analysis-of-the-regulation-of-the-photosynthetic-electron-transport-chain-in-c3-plants
#13
Alejandro Morales, Xinyou Yin, Jeremy Harbinson, Steven Michiel Driever, Jaap Molenaar, David M Kramer, Paul Struik
We present a new simulation model of the reactions in the photosynthetic electron transport chain of C3 species. We show that including recent insights about the regulation of the thylakoid proton motive force, ATP/NADPH balancing mechanisms (cyclic and non-cyclic alternative electron transport), and regulation of Rubisco activity, leads to emergent behaviors that may affect the operation and regulation of photosynthesis under different dynamic environmental conditions. The model was parameterized with experimental results in the literature, with a focus on Arabidopsis thaliana...
September 18, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28923742/effects-of-calcination-temperature-and-heating-rate-on-the-photocatalytic-properties-of-zno-prepared-by-pyrolysis
#14
Lingling He, Zhifang Tong, Zhonghua Wang, Ming Chen, Ni Huang, Wei Zhang
A series of ZnO nanorods were prepared by pyrolysis of zinc acetate at different calcination temperatures and heating rates under ambient atmosphere. The as-prepared ZnO nanorods were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performances of the ZnO nanorods were evaluated by the photodegradation of methyl orange (MO) and 4-nitrophenol (4-NP). The morphology, optical property, surface composition, and photocatalytic performance of the ZnO samples were affected by both calcination temperature and heating rate...
September 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28923730/kinetics-analysis-of-interfacial-electron-transfer-processes-in-goethite-suspensions-systems
#15
Jianzhong Ma, Chengzhu Zhu, Jun Lu, Bin Ouyang, Qiaoqin Xie, Haibo Liu, Shuchuan Peng, Tianhu Chen
The photochemical behavior of goethite has been one of the most important topics in the field of environmental science due to it plays a significant role in the removal and transformation process of numerous pollutants. However, the interfacial electron transfer process of goethite is not clear. Using a nanosecond laser flash photolysis spectrometer, we report the transient spectroscopic observations of interfacial electron-transfer reactions in goethite dispersion under UV irradiation. Excitation of goethite generated conduction-band electron (ecb(-)) and hole (h(+))...
September 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28922753/effects-of-periodic-photoinhibitory-light-exposure-on-physiology-and-productivity-of-arabidopsis-plants-grown-under-low-light
#16
Yonglan Tian, Joanna Sacharz, Maxwell A Ware, Huayong Zhang, Alexander V Ruban
This work examined the long-term effects of periodic high light stress on photosynthesis, morphology, and productivity of low-light-acclimated Arabidopsis plants. Significant photoinhibition of Arabidopsis seedlings grown under low light (100 μmol photons m-2 s-1) was observed at the beginning of the high light treatment (three times a day for 30 min at 1800 μmol photons m-2 s-1). However, after 2 weeks of treatment, similar photosynthesis yields (Fv/Fm) to those of control plants were attained. The daily levels of photochemical quenching measured in the dark (qPd) indicated that the plants recovered from photoinhibition within several hours once transferred back to low light conditions, with complete recovery being achieved overnight...
July 10, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28922640/a-novel-spectroscopic-analysis-to-detect-photochemical-reaction-of-the-bronchodilator-doxofylline-and-its-estimation-in-pharmaceutical-formulation
#17
P Sasi Rekha, S Gunasekaran
Photostability studies of drugs and drug products are an integral part of the product development process in the pharmaceutical industry. These studies are carried out to ensure quality, efficacy and safety of the formulated products during manufacture, storage and use. In this investigation, a novel spectroscopic approach has been adopted by employing the FTIR-ATR and UV/Visible techniques to detect the photochemical reactions of the drug Doxofylline, chemically designated as 7-(1, 3 dioxolane-2-yl methyl) theophylline, in its raw (pure) form...
September 11, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28922485/novel-3d-semiconducting-open-frameworks-based-on-cuprous-bromides-with-visible-light-driven-photocatalytic-properties
#18
Xiao-Wu Lei, Cheng-Yang Yue, Jun-Chao Wei, Rui-Qing Li, Fu-Qi Mi, Yan Li, Lu Gao, Quan-Xiu Liu
Visible light driven photocatalysts based on crystalline microporous metal halogenides received much less attention compared with dense or composite oxide semiconductors. Using the well-known photosensitive transition metal-complexes [TM(2,2-bipy)3 ](2+) (TM=Fe, Co, Ni, Ru) as templates, a special three-dimensional (3D) metal halogenide framework of [TM(2,2-bipy)3 ]Cu4 Br6 was designed with [Cu4 Br4 ] cluster as 4-connected node. These microporous materials feature narrow band gaps and stable visible light driven photocatalytic properties including water reduction to provide H2 and photodegradation of organic pollutants...
August 9, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28922481/photo-induced-assembly-of-a-luminescent-tetraruthenium-square
#19
Baptiste Laramée-Milette, Francesco Nastasi, Fausto Puntoriero, Sebastiano Campagna, Garry S Hanan
Self-assembly is a powerful synthetic tool that has led to the development of one-, two- and three-dimensional architectures. From MOFs to molecular flasks, self-assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de-construction of a supramolecular structure through unprecedented photo-induced assembly and dis-assembly. The combination of two approaches, a [n×1]-directional bonding strategy and a ligand photo-dissociation strategy, allows the photo-induced assembly of a polypyridyl Ru(II) precursor into a discrete molecular square...
September 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28920666/a-softoxometalate-k6-5cu-oh-8-5-h2o-7-5-0-5-k3pw12o40-n-n-1348-2024-as-an-efficient-inorganic-material-for-co2-reduction-with-concomitant-water-oxidation
#20
Santu Das, Saurabh Kumar, Somenath Garai, Ramudu Pochamoni, Shounik Paul, Soumyajit Roy
An immediate challenge for chemists is to devise different methods to trap chemical energy using light by reduction of carbon dioxide to a transportable fuel. To reach this goal the major obstacle lies in finding a suitable material that is abundant and possesses catalytic power to effect such reduction reaction and perform this reduction reaction without using any external photosensitizer. Here we report first time a softoxometalate, based on {[K6.5Cu(OH)8.5(H2O)7.5]0.5[K3PW12O40]} metal oxide framework which is stable in reaction condition that effectively performs photochemical CO2 reduction reaction in water with a very high turnover number of 613 and TOF of 47...
September 18, 2017: ACS Applied Materials & Interfaces
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