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1.
Nadar L Sayah R Vocanson F Crespo-Monteiro N Boukenter A Sao Joao S Destouches N 《Photochemical & photobiological sciences》2011,10(11):1810-1816
Silver nanoparticles were created inside mesoporous titania thin films by different reduction processes. We investigated the influence of the reduction method on the colour and photochromism of these amorphous TiO(2) films. The results highlight brown films by optical reduction, gray films by thermal reduction, and red, purple or orange films by chemical reduction. The different size distributions and localizations of the nanoparticles, characterized by UV-visible spectroscopy and electron microscopy, give various photochromic behaviours when exposed to visible laser light. We especially report the bleaching of different film colours under laser exposure. 相似文献
2.
After the discoveries of pre-Acheulian and Acheulian industry accumulations in the depression of the external ring of Guelb er Richât (Mauritanian Adrar) by Théodore Monod, it was proceeded to an exhaustive study of surrounding Quaternary sediments. Slopes in the south of the cliffs of Ordovician quartzite sandstones are covered with chaos of blocks where from go down torrential ravines which fed irregularly the alluvial plains of oueds Akerdil and Bamouéré. The torrential alluviums consist from two- to three-graded sequences of coarse sediments which were studied since the foot of the cliff down to alluvial fans. The datings of tests of mollusks of brackish waters and of phreatogenic calcitic cementations allowed to obtain a coherent chronostratigraphy based on 11 datings AMS of the 14C. These ages included between 15.000 and 7.730 BP correspond to the last climatic optimum or African Humid Period. Textural and mineralogical analyses of the torrential sequences allow to show a duality of origin of the materials of the accumulation partly deriving from more or less degraded Cambro-Ordovician basement (proximal source) and partly renewed by wind contributions during the long Meso-Cenozoic emersion (distal source). The palaeomagnetic measurements indicate that the great majority of the deposits accumulated during the last one normal magnetozone. Some altered deposits intermediate between the Paleozoic basement and the torrential sequences of the Late Quaternary present a negative magnetic inclination and a strong magnetic susceptibility linked to the presence of hematite grains; they are likened to more or less in situ reworked Cambrian-Ordovician tops. These conclusions leave not enough hope to identify on the slopes of Early Pleistocene sediments contemporary of the first Human populations. The strong accumulations of chopping-tools of the Akerdil Oued and of coarse hand-axes of the ravines of Cherirat indicate a credibly autochton origin of these big tools made in situ and which were concentrated by the successive wind deflations. Their mechanical dispersal was limited by their big size and by frequent calcitic cementations, such processes of fossilization were able to develop and to repeat during the ancient episodes of the Pleistocene. This hypothesis would lead us to envisage probable industry remains buried in depth into the filling of the outer alluvial plain of the Guelb er Richât. 相似文献
3.
C. Sao Emani M.J. Williams P.D. Van Helden M.J.C. Taylor I.J. Wiid B. Baker 《Biochemical and biophysical research communications》2018,495(1):174-178
Mycobacterium tuberculosis (M.tb.), the causative agent of tuberculosis (TB), cannot synthesize GSH, but synthesizes two major low molecular weight thiols namely mycothiol (MSH) and ergothioneine (ERG). Gamma-glutamylcysteine (GGC), an intermediate in GSH synthesis, has been implicated in the protection of lactic acid bacteria from oxidative stress in the absence of GSH. In mycobacteria, GGC is an intermediate in ERG biosynthesis, and its formation is catalysed by EgtA (GshA). GGC is subsequently used by EgtB in the formation of hercynine-sulphoxide-GGC. In this study, M.tb. mutants harbouring unmarked, in-frame deletions in each of the fives genes involved in ERG biosynthesis (egtA, egtB, egtC, egtD and egtE) or a marked deletion of the mshA gene (required for MSH biosynthesis) were generated. Liquid chromatography tandem mass spectrometry analyses (LC-MS) revealed that the production of GGC was elevated in the MSH-deficient and the ERG-deficient mutants. The ERG-deficient ΔegtB mutant which accumulated GGC was more resistant to oxidative and nitrosative stress than the ERG-deficient, GGC-deficient ΔegtA mutant. This implicates GGC in the detoxification of reactive oxygen and nitrogen species in M.tb. 相似文献
4.
Evaluation of several protein a resins for application to multicolumn chromatography for the rapid purification of fed‐batch bioreactors
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Nicolas‐Julian Hilbold Xavier Le Saoût Eric Valery Laurence Muhr Jonathan Souquet Alain Lamproye Hervé Broly 《Biotechnology progress》2017,33(4):941-953
Most of the existing production capacity is based on fed‐batch bioreactors. Thanks to the development of more efficient cell lines and the development of high‐performance culture media, cell productivity dramatically increased. In a manufacturing perspective, it is necessary to clear as quickly as possible the protein A capture step to respect the manufacturing agenda. This article describes the methodology applied for the design of a multicolumn chromatography process with the objective of purifying as quickly as possible 1,000 and 15,000 L fed‐batch bioreactors. Several recent and reference protein A resins are compared based on characteristic values obtained from breakthrough curves. The importance and relevance of resin parameters are explained, and purposely simple indicators are proposed to quickly evaluate the potential of each candidate. Based on simulation data, the optimum BioSC systems associated with each resin are then compared. The quality of the elution delivered by each resin is also compared to complete the assessment. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:941–953, 2017 相似文献
5.
应用免疫组织化学ABC法和神经节切除术,观察了16只自发性高血压鼠(分手术Ⅰ、Ⅱ、Ⅲ组和对照组)脑底动脉主要分支神经肽Y能神经纤维的起源,对照组自发性高血压鼠大脑前动脉,大脑中动脉,大脑后动脉和基底动脉壁上均可见棕褐色的神经肽Y能阳性纤维,纤维似曲线状,多呈网状走行,密度较高,手术Ⅰ组作双侧颈上神经节切除术,脑底动脉主要分支的阳性纤维明显减少,但不完全消失,手术Ⅱ组作双侧星状神经节切除术,脑底动脉主要分支壁上的阳性纤维明显减少;手术Ⅲ组作双侧颈上神经节和星状神经节切除术,脑底动脉主要分支的阳性纤维完全消失,结果提示;自发性高血压鼠脑底动脉主要分支神经肽Y能神经纤维起源于双侧颈上神经节和星状神经节,讨论了NPY神经在高血压时期在防御脑中风和血脑屏障破裂方面所起的作用。 相似文献
6.
Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+,Dy3+ co‐doped Ba2MgSi2O7 phosphors
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In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu2+‐doped and Eu2+,Dy3+‐co‐doped Ba2MgSi2O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid‐state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and energy‐dispersive X‐ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2MgSi2O7:Eu2+ showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2MgSi2O7:Eu2+Dy3+ showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f6 5d1 to 4f7 transition of Eu2+. TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu2+ doping in Ba2MgSi2O7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy3+ ions were co‐doped in Ba2MgSi2O7:Eu2+ and maximum TL intensity was observed for 2 mol% of Dy3+. TL emission spectra of Ba1.95MgSi2O7:0.05Eu2+ and Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co‐doping. The trap depths were calculated to be 0.54 eV for Ba1.95MgSi2O7:0.05Eu2+ and 0.54 eV and 0.75 eV for Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors. It was observed that co‐doping with small amounts of Dy3+ enhanced the thermoluminescence properties of Ba2MgSi2O7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f6 5d1', '4f7' has been corrected to '4f7', 'Ba1.95' has been corrected to 'Ba1.95' and 'Ba1.93' has been corrected to 'Ba1.93' respectively.] 相似文献
7.
Geetanjali Tiwari Nameeta Brahme Ravi Sharma D. P. Bisen Sanjay Kumar Sao Ishwar Prasad Sahu 《Luminescence》2016,31(8):1479-1487
A series of Ce3+ ion single‐doped Ca2Al2SiO7 phosphors was synthesized by a combustion‐assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X‐ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV‐irradiation excitation, the TL and ML emission spectra of Ca2Al2SiO7:Ce3+ phosphor showed the characteristic emission of Ce3+ peaking at 400 nm (UV–violet) and originating from the Ce3+ transitions of 5d‐4f (2F5/2 and 2F7/2). The photoluminescence (PL) emission spectra for Ca2Al2SiO7:Ce3+ were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca2Al2SiO7:Ce3+phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
Regulator of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) for Galpha subunits and negatively regulate G protein-coupled receptor signaling. Using RGS5 gene-specific RT-PCR, we have identified a novel alternative splicing variant of RGS5 mRNA in human ocular tissues. The alternative splicing of RGS5 mRNA occurred at position +44 (GenBank NM_003617), spliced out 174 bp (+44 to +218 bp) of the coding region, and encoded an RGS5s protein with a 108 amino acid N-terminal deletion. This study is the first to document alternative splicing of an RGS5 gene. We therefore studied RGS5 and RGS5s mRNA distribution in human tissues. In the eye, RGS5s was found to be highly expressed in the ciliary body and trabecular meshwork. It was also expressed in the kidney, brain, spleen, skeletal muscle and small intestine, but was not detectable in the liver, lung, heart. RGS5s was not found in monkey and rat ocular tissues, indicating species specificity for the eye. Comparing the recombinant RGS5 and RGS5s expression in HEK293/EBNA cells, RGS5s was present almost exclusively in the cytosolic fraction, whereas RGS5 was present in both membrane and cytosolic fractions. The data suggest that the N-terminal of RGS5 may be important for protein translocation to the cell membrane. Both RGS5 and RGS5s antagonized the rapid phosphorylation of p44/42 MAP kinase induced by Galphai coupled cannibinoid receptor-1 activation. RGS5, but not RGS5s, inhibited the Ca2+ signaling initiated by activation of Galphaq coupled angiotensin II receptors (AT1) and prostaglandin FP receptors. Cotransfection of RGS5s with RGS5 resulted in the blockade of RGS5 actions with respect to inhibition of the signal transduction initiated by activation of both AT1 and FP receptor, suggesting that RGS5s may contain functional domains that compete with RGS5 in the regulation of the Galphaq coupled AT1 and FP receptors. The unique expression pattern, cellular localization and functions of RGS5s suggest that RGS5s may play a critical role in the regulation of intracellular signaling pathways. 相似文献
9.
Sao Dilip Das Sandip Pramanik Subhamay Kuiri Probodh K. Nath Rajib 《Plasmonics (Norwell, Mass.)》2021,16(4):1319-1326
Plasmonics - The interplaying role of particle size and polymer layer thickness on the tunable optical response of polymer-coated Ag nanoparticles (NPs) has been studied experimentally and... 相似文献
10.
Ruben Wälchli Mariana Ressurreição Sebastian Vogg Fabian Feidl James Angelo Xuankuo Xu Sanchayita Ghose Zheng Jian Li Xavier Le Saoût Jonathan Souquet Hervé Broly Massimo Morbidelli 《Biotechnology and bioengineering》2020,117(3):687-700
Monoclonal antibodies (mAbs) and related recombinant proteins continue to gain importance in the treatment of a great variety of diseases. Despite significant advances, their manufacturing can still present challenges owing to their molecular complexity and stringent regulations with respect to product purity, stability, safety, and so forth. In this context, protein aggregates are of particular concern due to their immunogenic potential. During manufacturing, mAbs routinely undergo acidic treatment to inactivate viral contamination, which can lead to their aggregation and thereby to product loss. To better understand the underlying mechanism so as to propose strategies to mitigate the issue, we systematically investigated the denaturation and aggregation of two mAbs at low pH as well as after neutralization. We observed that at low pH and low ionic strength, mAb surface hydrophobicity increased whereas molecular size remained constant. After neutralization of acidic mAb solutions, the fraction of monomeric mAb started to decrease accompanied by an increase on average mAb size. This indicates that electrostatic repulsion prevents denatured mAb molecules from aggregation under acidic pH and low ionic strength, whereas neutralization reduces this repulsion and coagulation initiates. Limiting denaturation at low pH by d -sorbitol addition or temperature reduction effectively improved monomer recovery after neutralization. Our findings might be used to develop innovative viral inactivation procedures during mAb manufacturing that result in higher product yields. 相似文献