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Modification at Lattice Scale for an Optimized Optical Response of Al<sub>x</sub>(ZnO)<sub>1-x</sub>Nanostructures

World Journal of Nano Science and Engineering 2011年第1期1卷 15-19页

作者： Avanish Kumar Srivastava Karuppanan Senthil Melepurath Deepa Ruchi Gakhar jai shankar tawale 不详

We report the systematic changes of nano-scaled features and optical properties in a promising transparent oxide material, namely, Alx (x = 0, 1, 2 and 5%) doped ZnO1-x (AZO). Electron microscopy investigations revealed the alterations at lattice scale depending on the presence of Al-content in ZnO nanostructures. Lattice spacings of 0.26 and 0.28 nm oriented along the (0002) and (10 0) planes, respectively, were attributed to euhedral-and facetted-structures of hexagonal-ZnO. The AZO samples were further characterized by XRD, SEM, UV-vis spectrophotometry, Raman spectroscopy and photoluminescence studies. It has been shown that at a dopant concentration of 2%Al in ZnO, an optimal balance could be achieved between microstructure and optical properties.

关键词： Electron Microscopy Nanostructures ZnO Photoluminescence

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Stability of fluid flow in a Brinkman porous medium–A numerical study

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Journal of Hydrodynamics 2014年第5期26卷 681-688页

作者： shankar B.M. KUMAR jai SHIVAKUMARA I.S. 吴朝安 Department of Mathematics PES Institute of TechnologyBangalore 560 085India ISRO Satellite Centre Bangalore 560 017India Department of Mathematics Bangalore UniversityBangalore 560 001India Department of Mechanical Engineering The University of Hong Kong

The stability of fluid flow in a horizontal layer of Brinkman porous medium with fluid viscosity different from effective viscosity is investigated. A modified Orr-Sommerfeld equation is derived and solved numerically using the Chebyshev collocation method. The critical Reynolds number Re, the critical wave number ac and the critical wave speed cc are computed for various values of porous parameter and ratio of viscosities. Based on these parameters, the stability characteristics of the system are discussed in detail. Streamlines are presented for selected values of parameters at their critical state.

关键词： Brinkman model Chebyshev collocation method hydrodynamic stability modified Orr-Sommerfeld equation

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Visualizing Recovery of Cognitive Function in Stroke

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Journal of Behavioral and Brain Science 2013年第8期3卷 641-652页

作者： Andrea L. O. Hebb David Brandman jai shankar Adam O. Hebb Colorado Brain & Spine Institute LLC Englewood USA Department of Diagnostic Imaging QEII Hospital Halifax Canada Division of Neurosurgery Dalhousie University QEII Halifax Infirmary Site Halifax Canada

Hippocrates (460-377 BC) first described stroke over 2400 years ago. Stroke is the 4th leading cause of death in Canada (3rd in the USA) and the primary cause of permanent motor and cognitive disability. The majority of strokes are ischemic. The extent of cerebral dysfunction and thus the severity of stroke are based on the location, severity and duration of ischemia. Stroke management and prognosis encompass early recognition of the onset of stroke and post-stroke determination of the extent of brain injury aided by clinical stroke scores and diffusion-weighted imaging. Cognitive domains most likely to be affected following stroke are memory, orientation, language, attention and executive function. While the vast majority of functional recovery occurs within the first 3 months post-stroke, the neural mechanisms promoting recovery are not well understood. Investigations into the neural plasticity of brain areas after a lesion demonstrate that the adult brain can be shaped by environmental inputs, such as rehabilitation techniques. Many rehabilitation techniques are actively being pursued, including brain-computer interfaces providing sophisticated methods for detecting rehabilitation-associated changes in cerebral physiology. The success of such strategies visualized with functional magnetic resonance imaging and positron emission tomography may provide an objective complement to clinical evaluations.

关键词： Ischemia Magnetic Resonance Imaging Positron Emission Tomography Rehabilitation Brain-Computer Interface

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Does computed tomography permeability predict hemorrhagic transformation after ischemic stroke?

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World Journal of Radiology 2016年第6期8卷 594-599页

作者： Peggy Yen Allison Cobb jai jai Shiva shankar Department of Diagnostic Radiology Queen Elizabeth Ⅱ Health Sciences Centre

AIM: To use perfusion-derived permeability-surface area product maps to predict hemorrhagic transformation following thrombolytic treatment for acute ischemic ***: We retrospectively analyzed our prospectively kept acute stroke database over five consecutive months for patients with symptoms of acute ischemic stroke(AIS) who had computed tomography(CT) perfusion(CTP) done at arrival. Patients included in the analyses also had to have a follow-up CT. The permeability-surface area product maps(PS) was calculated for the side of the ischemia and/or infarction and for the contralateral unaffected side at the same level. The cerebral blood flow map was used to delineate the ischemic territory. Next, a region of interest was drawn at the centre of this territory on the PS parametric map. Finally, a mirror region of interest was created on the contralateral side at the same level. The relative permeability-surface area product maps(r PS) provided an internal control and was calculated as the ratio of the PS on the side of the AIS to the PS on the contralateral side. A student t-test was performed after log conversion of r PS between patients with and without hemorrhagic transformation. Log conversion was used to convert the data into normal distribution to use t-test. For the group of patients who experienced intracranial bleed, a student t-test was performed between those with only petechial hemorrhage and those with more severe parenchymal hematoma with subarachnoid ***: Of 84 patients with AIS and CTP at admission, only 42 patients had a follow-up CT. The r PSderived using the normal side as the internal control was significantly higher(P = 0.003) for the 15 cases of hemorrhagic transformation(1.71 + 1.64) compared to 27 cases that did not have any(1.07 + 1.30). Patients with values above the overall mean r PS of 1.3 had an increased likelihood of subsequent hemorrhagic transformation. The sensitivity of using this score to predict hemorrhagic

关键词： Stroke Mechanical thrombolysis Cerebral hemorrhage Capillary permeability Thrombolytic therapy

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