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Tailoring optical properties of TiO_2 in silica glass for limiting applications

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Chinese physics B 2014年第3期23卷 303-307页

作者： S.Divya Indu Sebastian v.p.n.nampoori p.Radhakrishnan A.Mujeeb International School of photonics Cochin University of Science and Technology

We present the linear and nonlinear optical studies on TiO2-SiO2 nanocomposites with varying compositions. Opti- cal band gap of the material is found to vary with the amount of SiO2 in the composite. The phenomenon of two-photon absorption （TpA） in TiO2/SiO2 nanocomposites has been studied using open aperture Z-scan technique. The nanocom- posites show better nonlinear optical properties than pure TiO2, which can be attributed to the surface states and weak dielectric confinement of TiO2 nanoparticles by SiO2 matrix. The nanocomposites are thermally treated and similar studies are performed. The anatase form of TiO2 in the nanocomposites shows superior properties relative to the amorphous and rutile counterpart. The involved mechanism is explained by rendering the dominant role played by the excitons in the TiO2 nanoparticles.

关键词： reverse saturable absorption (RSA) optical limiting excitons

Fabrication and photostability of Rhodamine-6G Gold nanoparticle Doped polymer Optical Fiber

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Chinese physics Letters 2013年第11期30卷 180-183页

作者： Suneetha Sebastian Ajina C C.p.G vallabhan v.p.n.nampoori p.Radhakrishnan M.Kailasnath International School of photonics Cochin University of Science and TechnologyCochin 22India

We report on fabrication of a rhodamine-6G-gold-nanoparticle doped polymer optical *** gold nanoparticle is synthesized directly into the monomer solution of the polymer using laser ablation synthesis in *** size of the particle is found from the transmission electron ***-6G is then mixed with the nanoparticle-monomer solution and optical characterization of the solution is *** is found that there is a pronounced quenching of fluorescence of rhodamine 6G due to fluorescence resonance energy *** monomer solution containing rhodamine 6G and gold nanoparticles is now made into a cylindrical rod and drawn into a polymer optical ***,the photostability is calculated with respect to the pure dye doped polymer optical fiber.

关键词： stability particle Rhodamine

Spectral Characterization of Laser Induced plasma from Titanium Dioxide

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plasma Science and Technology 2007年第4期9卷 456-459页

作者： v.J.DAnn M.v.MATHEW v.p.n.nampoori C.p.G.vALLABHAn v.M.nAnDAKUMARAn p.RADHAKRISHnAn International School of photonics Cochin University of Science and TechnologyCochin 22India Centre of Excellence in Lasers and Optoelectronic SciencesCochin University of Science and TechnologyCochin 22India International School of photonics Cochin University of Science and TechnologyCochin 22India Centre of Excellence in Lasers and Optoelectronic Sciences Cochin University of Science and TechnologyCochin 22India

Optical emission from TiO2 plasma, generated by a nanosecond laser is spectroscopically analysed. The main chemical species are identified and the spatio-temporal distribution of the plasma parameters such as electron temperature and density are characterized based on the study of spectral distribution of the line intensities and their broadening characteristics. The parameters of laser induced plasma vary quickly owing to its expansion at low background pressure and the possible deviations from local thermodynamic equilibrium conditions are tested to show its validity.

关键词： laser induced plasma titanium dioxide optical emission spectroscopy local thermodynamic equilibrium

Tuning the face orientation of ZnO nano/microcrystals by a wet chemical method

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Chinese Optics Letters 2013年第10期11卷 62-65页

作者： Aparna Thankappan Sheenu Thomas v.p.n.nampoori International School of photonics (ISp) Cochin University of Science and Technology Inter University Centre for nanomaterials and Devices (IUCnD) Cochin University of Science and Technology

We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods, nanoflakes, nanoplates, and microrods by a simple wet chemical method. Growth duration is found to play a crucial role in the morphologies of these ZnO nano/microcrystallites. In addition, growth conditions are systematically studied as a function of precursor concentration and temperature. The structural and optical characteristics of the ZnO samples are further investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence spectroscopy.

关键词： ZnO Tuning the face orientation of ZnO nano/microcrystals by a wet chemical method

performance of polymer/CdS organic-inorganic hybrid LEDs

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Optoelectronics Letters 2016年第2期12卷 110-114页

作者： C.pradeep S.Mathew M.A.G.namboothiry C.p.G.vallabhan p.Radhakrishnan v.p.n.nampoori International School of photonics Cochin University of Science and Technology School of physics Indian Institute of Science Education and Research Department of Optoelectronics University of Kerala

Organic-inorganic hybrid light emitting diodes(LEDs) were fabricated by incorporating cadmium sulphide(Cd S) nanoparticles in hole transporting layer and light emitting materials of a polymer LED. The Cd S nanoparticles with size of 10 nm were synthesized by precipitation technique. The LEDs incorporated with the Cd S nanoparticles show a reduction in turn on voltage and luminance. When the nanoparticles are incorporated in a suitable fluorene based light emitting polymer, the luminance is increased along with the decrease of turn on voltage.

关键词： inorganic incorporated transporting blend cadmium coated hexagonal filtered adding attributed

激光及γ射线对有丝分裂染色体畸变感应现象的比较(英文)

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遗传 1997年第5期19卷 5-9页

作者： p.R.Unnikrishnapilai padmanambisan v.p.n.nampoori C.p.G.valabhan 印度科钦科学技术大学生物技术系印度S.D.学院植物学系印度科钦科学技术大学国际光学院

波长５１４ｎｍ的激光照射可用于研究激光导致有丝分裂染色体畸变的效应。本文提供了一种新的辐照系统，能用于研究突变的感应现象，并与从γ－线辐射源获得的结果进行了比较。

关键词：氩离子激光染色体畸变有丝分裂 γ射线

Electronic and optical properties of TiO_2 and its polymorphs by Z-scan method

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Chinese physics B 2014年第8期23卷 340-344页

作者： S. Divya v.p.n.nampoori p Radhakrishnan A Mujeeb International School of photonics Cochin University of Science and Technology

TiO2 is a material which has attracted considerable attention from the scientific community for its innumerable prop- erties. TiO2 is known to exist in nature in three different crystalline structures： rutile, anatase, and brookite. Anatase and rutile TiO2 films have been widely characterized for their potential applications in solar cells, self-cleaning coatings, and photocatalysis. In the present report, the third-order nonlinear susceptibilities of TiO2 and its polymorphs, anatase, and rutile, prepared by the sol-gel technique followed by heat treatment are investigated using the Z-scan technique at a wavelength of 532 nm with a duration of 7 ns. Imaginary and real values of Z（3） for amorphous, anatase, and rutile are also calculated and found to be 5 × 10^-19 m2/v2, 27 × 10^-19 m2/v2, 19 × 10^-19 m2/v2, respectively. It is found that the values of the optical constants of amorphous TiO2 after heat treatment vary considerably. It is assumed that this could be due to the variation in the electronic structure of TiO2 synchronous with the formation of its polymorphs, anatase, and rutile. Amorphous TiO2 is marked by the localization of the tail states near the band gap, whereas its crystalline counterparts are characterized by completely delocalized tail states.

关键词： excitons reverse saturable absorption (RSA) excitonic nonlinearity

Unlocking hypoglycemia–associated brain microvascular dysfunction:critical insights from proteomic analysis

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neural Regeneration Research 2025年第6期20卷 1707-1708页

作者： Siva S.v.p.Sakamuri Anil Sakamuri Department of Chemistry Auburn University at MontgomeryMontgomeryALUSA vascular Biology Center and Department of Medicine Medical College of Georgia at Augusta UniversityAugustaGAUSA

Hypoglycemia-a critical complication linked to worsened brain function in diabetic subjects:Hypoglycemia is characterized by a decline in circulatory glucose levels below sta nda rd physiological *** hypoglycemia,classified as level 1 hypoglycemia,is defined by blood glucose levels below 70 mg/dL and can be effectively addressed through carbohydrate *** hypoglycemia,denoted by blood glucose levels less than 54 mg/dL,poses a life-threatening risk if left *** with type 1 and type 2 diabetes undergoing insulin treatment are particularly susceptible to hypoglycemia due to impaired counterregulatory mechanisms.

关键词： impaired intake critical

Impacts of pI3K/protein kinase B pathway activation in reactive astrocytes: from detrimental effects to protective functions

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neural Regeneration Research 2025年第4期20卷 1031-1041页

作者： Ramón pérez-núñez María Fernanda González Ana María Avalos Lisette Leyton Cellular Communication Laboratory Programa de Biología Celular y MolecularCenter for Studies on ExerciseMetabolism and Cancer(CEMC)Instituto de Ciencias Biomédicas(ICBM)Facultad de MedicinaUniversidad de ChileSantiagoChile Advanced Center for Chronic Diseases(ACCDiS) Faculty of Chemical and Pharmaceutical Sciences&Faculty of MedicineUniversidad de ChileSantiagoChile Instituto de Ciencias Biomédicas Facultad de Ciencias de la SaludUniversidad Autónoma de ChileSantiagoChile

Astrocytes are the most abundant type of glial cell in the central nervous *** injury and inflammation,astrocytes become reactive and undergo morphological and functional *** on their phenotypic classification as A1 or A2,reactive astrocytes contribute to both neurotoxic and neuroprotective responses,***,this binary classification does not fully capture the diversity of astrocyte responses observed across different diseases and *** analysis has revealed that reactive astrocytes have a complex landscape of gene expression profiles,which emphasizes the heterogeneous nature of their *** actively participate in regulating central nervous system inflammation by interacting with microglia and other cell types,releasing cytokines,and influencing the immune *** phosphoinositide 3-kinase(pI3K)/protein kinase B(AKT)signaling pathway is a central player in astrocyte reactivity and impacts various aspects of astrocyte behavior,as evidenced by in silico,in vitro,and in vivo *** astrocytes,inflammatory cues trigger a cascade of molecular events,where nuclear factor-κB serves as a central mediator of the pro-inflammatory ***,we review the heterogeneity of reactive astrocytes and the molecular mechanisms underlying their *** highlight the involvement of various signaling pathways that regulate astrocyte reactivity,including the pI3K/AKT/mammalian target of rapamycin(mTOR),αvβ3 integrin/pI3K/AKT/connexin 43,and notch/pI3K/AKT *** targeting the inactivation of the pI3K/AKT cellular signaling pathway to control reactive astrocytes and prevent central nervous system damage,evidence suggests that activating this pathway could also yield beneficial *** dual function of the pI3K/AKT pathway underscores its complexity in astrocyte reactivity and brain function *** review emphasizes the importance of employing astrocyte-exclusive models to underst

关键词： inflammation integrins neuroprotective neurotoxic phosphatidylinositol 3-kinase reactive astrocytes signal transduction Thy-1(CD90)