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Raghuvir K Arni - One of the best experts on this subject based on the ideXlab platform.
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chemical and Thermal Influence of the 4fe 4s 2 cluster of a g specific adenine glycosylase from corynebacterium pseudotuberculosis
Biochimica et Biophysica Acta, 2015Co-Authors: Raphael J Eberle, Monika A Coronado, Icaro Putinhon Caruso, Debora De Oliveira Lopes, Anderson Miyoshi, Vasco Azevedo, Raghuvir K ArniAbstract:Abstract The gram-positive bacteria Corynebacterium pseudotuberculosis, the causative agent of caseous lymphadenitis in livestock significantly reduces productivity and often causes death. The adenine/guanine-specific DNA glycosylase (MutY) prevents mutations in the DNA of the pathogen and a unique feature of the MutY protein family is the [4Fe–4S]2 + cluster that interlinks two protein subdomains. MutY from C. pseudotuberculosis was expressed in E. coli and purified, the CD experiments indicate a high content of α-helices and random coiled secondary structure and a typical near-UV CD fingerprint for the [4Fe–4S]2 + cluster. EDTA and copper sulfate possess a strong destabilizing effect on the [4Fe–4S]2 + cluster. UV–vis and fluorescence spectroscopy results demonstrate that between pH 3.0 and 4.0 the integrity of the [4Fe–4S]2 + cluster is destroyed. To investigate the Thermal stability of the protein differential scanning calorimetry and fluorescence spectroscopy were used and the Tm was determined to be 45 °C. The analysis presented provides information concerning the protein stability under different physio-chemical conditions.
Formoso M.l.l. - One of the best experts on this subject based on the ideXlab platform.
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An accurate record of volcanic ash fall deposition as characterized by dispersed organic matter in a Lower Permian tonstein bed (Faxinal Coalfield, Paraná Basin, Brazil)
2021Co-Authors: Simas M.w., Guerra-sommer M, Mendonça J.g., Cazzulo-klepzig, Filho M., Formoso M.l.l.Abstract:For the first time, the dispersed organic matter in the tonstein layer interbedded with a coal seam in the Faxinal Coalfield (Sakmarian, Southern Paraná Basin, Brazil) is characterized. The deposition of clusters of pollen grains was highly Influenced by the intense ash fall process that probably occurred during seasonal dehiscence of reproductive structures. The well-preserved phytoclasts with their upper and lower leaf cuticles stuck together indicate that the rapid fall of ash on this material hindered organic biodegradation. The preservation of seemingly autochthonous Botryococcus colonies at the top of the tonstein layer is evidence of the subaqueous deposition of this layer. The darkening in cuticles and xylem phytoclasts can be attributed to different causes: the Thermal Influence of ash fall during deposition, chemical effects of the ash, prolonged oxidation of organic matter in low water level conditions or the burning of plant organs by wildfires. Analyses of dispersed organic matter along the tonstein layer showed that the organic matter succession reflects the composition of different plant strata (herbaceous pteridophytes and arboreal glossopterids-cordaitaleans) around the deposition site
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An accurate record of volcanic ash fall deposition as characterized by dispersed organic matter in a lower Permian tonstein layer (Faxinal Coalfield, Paraná Basin, Brazil)
'Edicions de la Universitat de Barcelona', 2013Co-Authors: Simas M.w., Guerra-sommer M, MendonÇa Filho J.g., Cazzulo-klepzig M., Formoso M.l.l.Abstract:For the first time, the dispersed organic matter in the tonstein layer interbedded with a coal seam in the Faxinal Coalfield (Sakmarian, Southern Paraná Basin, Brazil) is characterized. The deposition of clusters of pollen grains was highly Influenced by the intense ash fall process that probably occurred during seasonal dehiscence of reproductive structures. The well-preserved phytoclasts with their upper and lower leaf cuticles stuck together indicate that the rapid fall of ash on this material hindered organic biodegradation. The preservation of seemingly autochthonous Botryococcus colonies at the top of the tonstein layer is evidence of the subaqueous deposition of this layer. The darkening in cuticles and xylem phytoclasts can be attributed to different causes: the Thermal Influence of ash fall during deposition, chemical effects of the ash, prolonged oxidation of organic matter in low water level conditions or the burning of plant organs by wildfires. Analyses of dispersed organic matter along the tonstein layer showed that the organic matter succession reflects the composition of different plant strata (herbaceous pteridophytes and arboreal glossopterids-cordaitaleans) around the deposition site
Katsumi Midorikawa - One of the best experts on this subject based on the ideXlab platform.
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multiwavelength excitation processing using f2 and krf excimer lasers for precision microfabrication of hard materials
Applied Surface Science, 2002Co-Authors: Koji Sugioka, Toshimitsu Akane, Kotaro Obata, Koichi Toyoda, Katsumi MidorikawaAbstract:Vacuum ultraviolet (VUV)–ultraviolet (UV) multiwavelength excitation processing for precision microfabrication of hard materials, in which simultaneous irradiation of the VUV and the UV laser beams leads to high-quality ablation and highefficiency modification, is reviewed. A coaxial irradiation system of F2 and KrF excimer lasers has been developed. This system achieves well-defined micropatterning of fused silica and GaN with little Thermal Influence and little debris deposition. Ablation mechanism is explained as absorption of KrF excimer laser by excited-states formed by F2 laser (excited-state absorption: ESA). Additionally, this technique is applied for more efficient refractive index modification of fused silica compared with single-F2 laser irradiation, which is attributed to resonance photoionization-like process based on ESA. The discussion includes characterization of optimum experimental conditions and features of the multiwavelength excitation processing. # 2002 Elsevier Science B.V. All rights reserved.
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Influence of laser fluence and irradiation timing of F2 laser on ablation properties of fused silica in F2-KrF excimer laser multi-wavelength excitation process
Applied Physics A: Materials Science and Processing, 2001Co-Authors: Kotaro Obata, N Aoki, Toshimitsu Akane, Koji Sugioka, Koichi Toyoda, Katsumi MidorikawaAbstract:A collinear irradiation system of F2 and KrF excimer lasers for high-quality and high-efficiency ablation of hard materials by the F2 and KrF excimer lasers' multi-wavelength excitation process has been developed. This system achieves well-defined micropatterning of fused silica with little Thermal Influence and little debris deposition. In addition, the dependence of ablation rate on various conditions such as laser fluence, irradiation timing of each laser beam, and pulse number is examined to investigate the role of the F2 laser in this process. The multi-wavelength excitation effect is strongly affected by the irradiation timing, and an extremely high ablation rate of over 30 nm/pulse is obtained between - 10 ns and 10 ns of the delay time of F2 laser irradiation. The KrF excimer laser ablation threshold decreases and its effective absorption coefficient increases with increasing F2 laser fluence. Moreover, the ablation rate shows a linear increase with the logarithm of KrF excimer laser fluence when the F2 laser is simultaneously irradiated, while single KrF excimer laser ablation shows a nonlinear increase. The ablation mechanism is discussed based on these results.
S B Orlinskii - One of the best experts on this subject based on the ideXlab platform.
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electron paramagnetic resonance study of rotational mobility of vanadyl porphyrin complexes in crude oil asphaltenes probing the effect of Thermal treatment of heavy oils
Energy & Fuels, 2014Co-Authors: Timur Biktagirov, M R Gafurov, M A Volodin, G V Mamin, A A Rodionov, V V Izotov, A V Vakhin, D R Isakov, S B OrlinskiiAbstract:The structural properties of crude oils and asphaltenes, especially related to the dynamics of their aggregation, have been investigated by different experimental and theoretical methods during the last few decades. However, there are only a few works devoted to study the dynamics of asphaltenes in a native hydrocarbon environment. In this report, we illustrate a possibility to use electron paramagnetic resonance (EPR) spectra of vanadyl porphyrins in asphaltenes for the qualitative and quantitative analysis of their rotational mobility in the crude oil samples. On the basis of the simulation of the EPR spectra, a simple semi-empirical parameter sensitive to the transition between motional regimes is proposed. This mobility parameter can be potentially useful for the prediction and analysis of the Thermal Influence on heavy oil reservoirs during hydrocarbon production. It is found that the rotational correlation time of the complexes in heavy oil samples changes discontinuously with the temperature. The o...
Raphael J Eberle - One of the best experts on this subject based on the ideXlab platform.
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chemical and Thermal Influence of the 4fe 4s 2 cluster of a g specific adenine glycosylase from corynebacterium pseudotuberculosis
Biochimica et Biophysica Acta, 2015Co-Authors: Raphael J Eberle, Monika A Coronado, Icaro Putinhon Caruso, Debora De Oliveira Lopes, Anderson Miyoshi, Vasco Azevedo, Raghuvir K ArniAbstract:Abstract The gram-positive bacteria Corynebacterium pseudotuberculosis, the causative agent of caseous lymphadenitis in livestock significantly reduces productivity and often causes death. The adenine/guanine-specific DNA glycosylase (MutY) prevents mutations in the DNA of the pathogen and a unique feature of the MutY protein family is the [4Fe–4S]2 + cluster that interlinks two protein subdomains. MutY from C. pseudotuberculosis was expressed in E. coli and purified, the CD experiments indicate a high content of α-helices and random coiled secondary structure and a typical near-UV CD fingerprint for the [4Fe–4S]2 + cluster. EDTA and copper sulfate possess a strong destabilizing effect on the [4Fe–4S]2 + cluster. UV–vis and fluorescence spectroscopy results demonstrate that between pH 3.0 and 4.0 the integrity of the [4Fe–4S]2 + cluster is destroyed. To investigate the Thermal stability of the protein differential scanning calorimetry and fluorescence spectroscopy were used and the Tm was determined to be 45 °C. The analysis presented provides information concerning the protein stability under different physio-chemical conditions.