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541.
William Wilson Anku Samuel Osei-Bonsu Oppong Sudheesh Kumar Shukl Eric Selorm Agorku Poomani Penny Govender 《自然科学进展(英文版)》2016,26(4):354-361
This paper reports the degradation of indigo carmine and eosin Y dyes in water, catalyzed by cobalt and multiwalled carbon nanotube modified zirconium oxide nanocomposite(Co-ZrO_2-MWCNTs) under simulated visible light. The bare ZrO_2,ZrO_2-MWCNTs, Co-ZrO_2 and Co-ZrO_2-MWCNTs with different percentage compositions of cobalt were synthesized by homogeneous co-precipitation method. Characterization of the prepared nanocomposites was carried out using X-Ray powder Diffraction(XRD), Fourier Transformer Infrared(FTIR) Spectroscopy, Transmission Electron Microscopy(TEM), Raman Spectroscopy,(UV–Vis)-Spectroscopy and Energy Dispersive Spectroscopy(EDS) for their structure, formation,morphology, size and elemental analysis. The experimental results indicated that all the cobalt and MWCNTs modified nanocomposites demonstrated higher photocatalytic activities compared to the bare ZrO_2. The most efficient catalyst(0.5% Co-ZrO_2-MWCNTs) with the band gap and Ka values of 5.21 e V and 16.86*10~(-3) min~(-1) respectively exhibited 98% degradation efficiency toward indigo carmine and 87% toward eosin Y in 180 min. 相似文献
542.
Weir BA Woo MS Getz G Perner S Ding L Beroukhim R Lin WM Province MA Kraja A Johnson LA Shah K Sato M Thomas RK Barletta JA Borecki IB Broderick S Chang AC Chiang DY Chirieac LR Cho J Fujii Y Gazdar AF Giordano T Greulich H Hanna M Johnson BE Kris MG Lash A Lin L Lindeman N Mardis ER McPherson JD Minna JD Morgan MB Nadel M Orringer MB Osborne JR Ozenberger B Ramos AH Robinson J Roth JA Rusch V Sasaki H Shepherd F Sougnez C Spitz MR Tsao MS Twomey D Verhaak RG Weinstock GM Wheeler DA Winckler W 《Nature》2007,450(7171):893-898
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Rasmussen SG Choi HJ Rosenbaum DM Kobilka TS Thian FS Edwards PC Burghammer M Ratnala VR Sanishvili R Fischetti RF Schertler GF Weis WI Kobilka BK 《Nature》2007,450(7168):383-387
Structural analysis of G-protein-coupled receptors (GPCRs) for hormones and neurotransmitters has been hindered by their low natural abundance, inherent structural flexibility, and instability in detergent solutions. Here we report a structure of the human beta2 adrenoceptor (beta2AR), which was crystallized in a lipid environment when bound to an inverse agonist and in complex with a Fab that binds to the third intracellular loop. Diffraction data were obtained by high-brilliance microcrystallography and the structure determined at 3.4 A/3.7 A resolution. The cytoplasmic ends of the beta2AR transmembrane segments and the connecting loops are well resolved, whereas the extracellular regions of the beta2AR are not seen. The beta2AR structure differs from rhodopsin in having weaker interactions between the cytoplasmic ends of transmembrane (TM)3 and TM6, involving the conserved E/DRY sequences. These differences may be responsible for the relatively high basal activity and structural instability of the beta2AR, and contribute to the challenges in obtaining diffraction-quality crystals of non-rhodopsin GPCRs. 相似文献
545.
The terrestrial and lunar cratering rate is often assumed to have been nearly constant over the past 3 Gyr. Different lines of evidence, however, suggest that the impact flux from kilometre-sized bodies increased by at least a factor of two over the long-term average during the past approximately 100 Myr. Here we argue that this apparent surge was triggered by the catastrophic disruption of the parent body of the asteroid Baptistina, which we infer was a approximately 170-km-diameter body (carbonaceous-chondrite-like) that broke up 160(-20)+30Myr ago in the inner main asteroid belt. Fragments produced by the collision were slowly delivered by dynamical processes to orbits where they could strike the terrestrial planets. We find that this asteroid shower is the most likely source (>90 per cent probability) of the Chicxulub impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago. 相似文献
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The influence of artificial shade on the distribution and abundance of juvenile chinook salmon was studied in a side channel of the South Fork Salmon River, Idaho. Fish biomass and abundance were greater in shaded than in unshaded areas when compared to both cumulative incident light reaching the study sections during the 72-hour test runs and instantaneous incident light conditions at the end of the 72-hour test runs. Because conditions may be atypical at the time of instantaneous light measurement, we prefer cumulative incident light for relating light and shade conditions to daytime distribution (abundance and biomass) of juvenile chinook salmon. 相似文献
550.
William J. Polacheck Ioannis K. Zervantonakis Roger D. Kamm 《Cellular and molecular life sciences : CMLS》2013,70(8):1335-1356
Tumor cell migration is essential for invasion and dissemination from primary solid tumors and for the establishment of lethal secondary metastases at distant organs. In vivo and in vitro models enabled identification of different factors in the tumor microenvironment that regulate tumor progression and metastasis. However, the mechanisms by which tumor cells integrate these chemical and mechanical signals from multiple sources to navigate the complex microenvironment remain poorly understood. In this review, we discuss the factors that influence tumor cell migration with a focus on the migration of transformed carcinoma cells. We provide an overview of the experimental and computational methods that allow the investigation of tumor cell migration, and we highlight the benefits and shortcomings of the various assays. We emphasize that the chemical and mechanical stimulus paradigms are not independent and that crosstalk between them motivates the development of new assays capable of applying multiple, simultaneous stimuli and imaging the cellular migratory response in real-time. These next-generation assays will more closely mimic the in vivo microenvironment to provide new insights into tumor progression, inform techniques to control tumor cell migration, and render cancer more treatable. 相似文献