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Intermodal group-velocity engineering for broadband nonlinear optics

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Photonics Research 2019年第1期7卷 1-7页

作者： JEFF DEMAS LARS RISH?J XIAO LIU GAUTAM PRABHAKAR SIDDHARTH ramachandran Department of Electrical Engineering Boston University The Rockefeller University

Interest in the nonlinear properties of multi-mode optical waveguides has seen a recent resurgence on account of the large dimensionality afforded by the platform. The large volume of modes in these waveguides provides a new spatial degree of freedom for phase matching nonlinear optical processes. However, this spatial dimension is quantized, which narrows the conversion bandwidths of intermodal processes and constrains spectral and temporal tailoring of the light. Here we show that by engineering the relative group velocity within the spatial dimension, we can tailor the phase-matching bandwidth of intermodal parametric nonlinearities. We demonstrate group-velocity-tailored parametric nonlinear mixing between higher-order modes in a multi-mode fiber with gain bandwidths that are more than an order of magnitude larger than that previously thought possible for intermodal four-wave mixing. As evidence of the technological utility of this methodology, we seed this process to generate the first high-peak-power wavelength-tunable all-fiber quasi-CW laser in the Ti:sapphire wavelength *** generally, with the combination of intermodal interactions, which dramatically expand the phase-matching degrees of freedom for nonlinear optics, and intermodal group-velocity engineering, which enables tailoring of the bandwidth of such interactions, we showcase a platform for nonlinear optics that can be broadband while being wavelength agnostic.

关键词： nonlinear properties waveguides optical processes

Electronic structure and bonding interactions in Ba1-xSrxZr0.1Ti0.9O3 ceramics

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Frontiers of Materials Science 2017年第2期11卷 182-189页

作者： Jegannathan MANGAIYARKKARASI Subramanian SASIKUMAR Olai Vasu SARAVANAN ramachandran SARAVANAN PG and Research Department of Physics NMSSVN College Nagamalai Madurai-625 019 Tamil Nadu India Research Centre and PG Department of Physics The Madura College Madurai-625 011 Tamil Nadu India

An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1-xSrxZr0.1Ti0.9O3 （short for BSZT, x = 0, 0.05, 0.07 and 0.14） ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method （MEM）. Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiOz structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.

关键词： barium titanate X-ray diffraction Rietveld refinement maximum entropy method bonding

Electrochemical process of titanium extraction

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中国有色金属学会会刊：英文版 2007年第2期17卷 429-433页

作者： CH. RVS. NAGESH C. S. ramachandran Defence Metallurgical Research Laboratory HyderabadA.P. India-500058

A wide variety of processes are being pursued by researchers for cost effective extraction of titanium metal. Electrochemical processes are promising due to simplicity and being less capital intensive. Some of the promising electrochemical processes of titanium extraction were reviewed and the results of laboratory scale experiments on electrochemical reduction of TiO2 granules were brought out. Some of the kinetic parameters of the reduction process were discussed while presenting the quality improvements achieved in the experimentation.

关键词：钛萃取电化学还原过程动力学参数

Adaptive Window Based 3-D Feature Selection for Multispectral Image Classification Using Firefly Algorithm

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Computer Systems Science & Engineering 2023年第1期44卷 265-280页

作者： M.Rajakani R.J.Kavitha A.ramachandran Full Time Research Scholar Department of Electronics and Communication EngineeringUniversity College of EngineeringPanruti607106India Department of Electronics and Communication Engineering University College of EngineeringPanruti607106India Department of Computer Science and Engineering University College of EngineeringPanruti607106India

Feature extraction is the most critical step in classification of multispectral *** classification accuracy is mainly influenced by the feature sets that are selected to classify the *** the past,handcrafted feature sets are used which are not adaptive for different image *** overcome this,an evolu-tionary learning method is developed to automatically learn the spatial-spectral features for classification.A modified Firefly Algorithm(FA)which achieves maximum classification accuracy with reduced size of feature set is proposed to gain the interest of feature selection for this *** extracting the most effi-cient features from the data set,we have used 3-D discrete wavelet transform which decompose the multispectral image in all three *** selecting spatial and spectral features we have studied three different approaches namely overlapping window(OW-3DFS),non-overlapping window(NW-3DFS)adaptive window cube(AW-3DFS)and Pixel based *** Multiclass Support Vector Machine(MSVM)is used for classification *** con-ducted on Madurai LISS IV multispectral image exploited that the adaptive win-dow approach is used to increase the classification accuracy.

关键词： Multispectral image modifiedfireﬂy algorithm 3-D feature extraction feature selection multiclass support vector machine classification

Thermodynamic behaviors of SiCl_2 in silicon deposition by gas phase zinc reduction of silicon tetrachloride

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Chinese Journal of Chemical Engineering 2015年第3期23卷 552-558页

作者：侯彦青聂陟枫谢刚李荣兴俞小花 Plant A ramachandran State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Kunming University of Science and Technology Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming Metallurgical Research Institute Department of Energy Environmental and Chemical Engineering Washington University in St.Louis

The modified Siemens process,which is the major process of producing polycrystalline silicon through current technologies,is a high temperature,slow,semi-batch process and the product is expensive primarily due to the large energy ***,the zinc reduction process,which can produce solar-grade silicon in a cost effective manner,should be redeveloped for these *** SiCl2 generation ratio,which stands for the degree of the side reactions,can be decomposed to SiCl4 and ZnCl2 in gas phase zinc atmosphere in the exit where the temperature is very ***,the lower SiCl2 generation ratio is profitable with lower power *** on the thermodynamic data for the related pure substances,the relations of the SiCl2 generation ratio and pressure,temperature and the feed molar ratio（n（Zn）/n（SiCl4） are investigated and the graphs thereof are *** the diagrams of Kpθ-T at standard atmosphere pressure have been plotted to account for the influence of temperature on the SiCl2 generation ***,the diagram of Kpθ-T at different pressures have also been plotted to give an interpretation of the influence of pressure on the SiCl2 generation *** results show that SiCl2 generation ratio increases with increasing temperature,and the higher pressure and excess gas phase zinc can restrict SiCl2 generation ***,suitable operational conditions in the practical process of polycrystalline silicon manufacture by gas phase zinc reduction of SiCl4 have been established with 1200 K,0.2 MPa and the feed molar ratio（n（Zn） /n（SiCl4）） of 4 at the *** these conditions,SiCl2 generation ratio is very low,which indicates that the side reactions can be restricted and the energy consumption is reasonable.

关键词： Polycrystalline silicon Thermodynamics Gas phase zinc reduction process SiCl2 generation ratio

Antipyretic,anti-inflammatory and analgesic properties of nilavembu kudineer choornam:a classical preparation used in the treatment of chikungunya fever

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Asian Pacific Journal of Tropical Medicine 2011年第10期4卷 819-823页

作者： Anbarasu K Manisenthil Kumar KT ramachandran S Government Hospital KrishnarayapuramKarur-639102Tamil NaduIndia Department of Pharmacology KMCH College of PharmacyCoimbatore-641048Tamil NaduIndia

Objective:To investigate the efficacy of ethanolic extract of nilavembu kudineer choornam (EENKC) in inflammation,pain and fever using animal models to support its ***: Acute toxicity study of EENKC was performed in mice to fix the effective *** antipyretic, anti-inflammatory and analgesic activity of EENKC was evaluated in brewer’s yeast induced pyrexia in rats,carrageenan-induced inflammation in rats and acetic-acid induced writhing in mice ***:Acute toxicity revealed that EENKC didn’t show death and toxic signs up to 2 000 mg/*** brewer’s yeast induced pyrexia and carrageenan-induced inflammation EENKC at the doses of 200 and 400 mg/kg inhibited fever and inflammation significantly(P<0.01 and<0.05) compared to control *** mice,the number of writhing induced by acetic-acid was significantly(P<0.01) reduced after treatment with both the dose of EENKC than control animals. EENKC 200 mg/kg inhibits inflammation higher level in carrageenan-induced paw edema,but there is no significant difference when compared to indomethacin 10 mg/***:The present findings revealed that EENKC possesses antipyretic,anti-inflammatory and analgesic activity which supports nilavembu kudineer choornam efficacy in chikungunya fever.

关键词： Antipyretic Anti-inflammatory Analgesic Chikungunya fever

Differential changes in intrinsic innervation and interstitial cells of Cajal in small bowel atresia in newborns

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World Journal of Gastroenterology 2010年第45期16卷 5716-5721页

作者： Stefan Gfroerer Roman Metzger Henning Fiegel Priya ramachandran Udo Rolle Department of Paediatric Surgery Johann Wolfgang Goethe-University Frankfurt/MTheodor-Stern-Kai 760590 Frankfurt/MGermany Department of Paediatric Surgery University of Leipzig04103 LeipzigGermany Department of Pediatric Surgery Kanchi Kamakoti Childs Trust Hospital12-A ChennaiIndia

AIM: To investigate morphological changes of the enteric nervous system (ENS) and the interstitial cells of Cajal (ICCs) in small bowel ***: Resected small bowel specimens from affected patients (n = 7) were divided into three parts (proximal, atretic, distal). Standard histology and enzyme immunohistochemistry anti-S100, anti-protein gene product (PGP) 9.5, anti-neurofilament (NF), antic-kit-receptor (CD117) was carried out on conventional paraffin sections of the proximal and distal part. RESULTS: The neuronal and glial markers (PGP 9.5, NF, S-100) were expressed in hypertrophied ganglia and nerve fibres within the myenteric and submucosal plexuses. Furthermore, the submucous plexus contained typical giant ganglia. The innervation pattern of the proximal bowel resembled intestinal neuronal dysplasia. The density of myenteric ICCs was clearly reduced in the proximal bowel, whereas a moderate number of muscular ICCs were found. The anti-CD117 immunore- action revealed additional numerous mast cells. The distal bowel demonstrated normal morphology and density of the ENS, the ICCs and the mast ***: The proximal and distal bowel in small bowel atresia revealed clear changes in morphology and density of the ENS and ICCs.

关键词： Small bowel atresia Enteric nervous system Gastrointestinal motility Interstitial cells of Cajal

Electrodeposition of aluminium and aluminium-copper alloys from a room temperature ionic liquid electrolyte containing aluminium chloride and triethylamine hydrochloride

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International Journal of Minerals,Metallurgy and Materials 2013年第9期20卷 909-916页

作者： P.V. Suneesh T.G. Satheesh Babu T. ramachandran Department of Sciences Amrita School of Engineering Amrita Vishwa Vidyapeetham Amritanagar P. O.Coimbatore - 641112India

The electrodeposition of A1 and A1-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing A1C13-EtaNHC1 was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry （CV）, and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy （SEM-EDS） and X-ray diffraction （XRD）. A1 of 70μm in thickness and an A1-Cu alloy of 30μm in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the A1 deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be （30±5） and （29±5） nm, respectively, for A1 and A1-Cu alloys. Potentiodynamic polarization （Tafel plots） and electrochemical impedance spectroscopic （EIS） measurements showed that Al-Cu alloys are more corrosion resistant than Al.

关键词： electrodeposition aluminium copper alloys ionic liquids triethylamine hydrochloride copper acetylacetonate

Changes of smooth muscle contractile filaments in small bowel atresia

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World Journal of Gastroenterology 2012年第24期18卷 3099-3104页

作者： Stefan Gfroerer Henning Fiegel Priya ramachandran Udo Rolle Roman Metzger Department of Paediatric Surgery Goethe-University Frankfurt60590 FrankfurtGermany Kanchi Kamakoti Childs Trust Hospital Chennai 600034India Department of Paediatric Surgery University of Leipzig04317 LeipzigGermany

AIM:To investigate morphological changes of intestinal smooth muscle contractile fibres in small bowel atresia ***:Resected small bowel specimens from small bowel atresia patients(n = 12) were divided into three sections(proximal,atretic and distal).Standard histology hematoxylin-eosin staining and enzyme immunohistochemistry was performed to visualize smooth muscle contractile markers-smooth muscle actin(SMA) and desmin using conventional paraffin sections of the proximal and distal *** bowel from agematched patients(n = 2) undergoing Meckel's diverticulum resection served as ***:The smooth muscle coat in the proximal bowel of small bowel atresia patients was thickened compared with control tissue,but the distal bowel was *** of smooth muscle contractile fibres SMA and desmin within the proximal bowel was slightly reduced compared with the distal bowel and control *** were no major differences in the architecture of the smooth muscle within the proximal bowel and the distal *** proximal and distal bowel in small bowel atresia patients revealed only minimal differences regarding smooth muscle morphology and the presence of smooth muscle contractile filament ***:Changes in smooth muscle contractile filaments do not appear to play a major role in postoperative motility disorders in small bowel atresia.

关键词： Small bowel atresia Enteric nervous sys-tem Smooth muscle Motility disorder