Continuous refractive index sensing based on carbon-nanotube-deposited photonic crystal fibers

We present a carbon nanotubes (CNTs) deposited photonic crystal fiber (PCF) featuring a Mach-Zehnder interferometer configuration for refractive index (RI) sensing applications. The high RI of the CNTs deposited on the surface of the PCF not only enhances the interaction of the evanescent waves of the cladding modes with the ambient environment around the fiber, but also modifies the sensing scheme to that of intensity variations. Such a modification makes the sensor susceptible to power fluctuations from the optical source but allows the sensor to gain immunity to free spectral range limitations which is commonly found in PCF-based sensors. As such continuous and repeatable measurements can be obtained for the range of RIs being measured. The sensor registered a sensitivity of 19.4 dB/RIU within the RI range of 1.33 to 1.38 and a sensitivity of 24.2 dB/RIU within the RI range of 1.38 to 1.42. Since there is no mechanical modification of the overall structure of the sensing element, the fiber retains its mechanical strength which makes it viable for practical applications. The experimental results are found to be consistent with the modeling of the sensor's behavior. © 2014 Elsevier B.V

Carbon-nanotube-deposited long period fiber grating for continuous refractive index sensor applications

We present a carbon-nanotube-deposited long period fiber grating for refractive index sensing applications in liquid. Carbon nanotubes are deposited around the surface of a long period fiber grating to form the refractive index sensing element. The sensing mechanism relies mainly on the high refractive index properties of the carbon-nanotube thin film, which enhances the cladding mode of the long period fiber grating in order to have a significant interaction between the propagating light and the target medium. A sensitivity of 31 dB/RIU and 47 dB/RIU are obtained for the refractive index ranges of 1.33-1.38 and 1.38-1.42, respectively, which have not been demonstrated with normal long period fiber gratings as the sensing element. As the sensing mechanism is based on the change of the transmitted optical power, our proposed scheme can intrinsically solve the limitations of the free spectral range commonly seen in other reported schemes, and continuous and repeatable measurements can be obtained while only acquiring errors mainly from the power fluctuations from the light source. The fiber grating also does not require any further mechanical modification like etching or tapering, which allows the sensing element to have the advantage of mechanical strength for practical applications. The experimental results are consistent with the modeling of the sensing mechanism. © 2014 Elsevier B.V. All rights reserved

Transcriptomic Signatures of Ash (Fraxinus spp.) Phloem

Ash (Fraxinus spp.) is a dominant tree species throughout urban and forested landscapes of North America (NA). The rapid invasion of NA by emerald ash borer (Agrilus planipennis), a wood-boring beetle endemic to Eastern Asia, has resulted in the death of millions of ash trees and threatens billions more. Larvae feed primarily on phloem tissue, which girdles and kills the tree. While NA ash species including black (F. nigra), green (F. pennsylvannica) and white (F. americana) are highly susceptible, the Asian species Manchurian ash (F. mandshurica) is resistant to A. planipennis perhaps due to their co-evolutionary history. Little is known about the molecular genetics of ash. Hence, we undertook a functional genomics approach to identify the repertoire of genes expressed in ash phloem.Using 454 pyrosequencing we obtained 58,673 high quality ash sequences from pooled phloem samples of green, white, black, blue and Manchurian ash. Intriguingly, 45% of the deduced proteins were not significantly similar to any sequences in the GenBank non-redundant database. KEGG analysis of the ash sequences revealed a high occurrence of defense related genes. Expression analysis of early regulators potentially involved in plant defense (i.e. transcription factors, calcium dependent protein kinases and a lipoxygenase 3) revealed higher mRNA levels in resistant ash compared to susceptible ash species. Lastly, we predicted a total of 1,272 single nucleotide polymorphisms and 980 microsatellite loci, among which seven microsatellite loci showed polymorphism between different ash species.The current transcriptomic data provide an invaluable resource for understanding the genetic make-up of ash phloem, the target tissue of A. planipennis. These data along with future functional studies could lead to the identification/characterization of defense genes involved in resistance of ash to A. planipennis, and in future ash breeding programs for marker development

Charge transfer assisted nonlinear optical and photoconductive properties of CdS-AgInS2 nanocrystals grown in semiconducting polymers

10.1063/1.4798383Journal of Applied Physics11312-JAPI

Synthesis and nonlinear optical switching of Bi2S3 nanorods and enhancement in the NLO response of Bi2S3@Au nanorod-composites

10.1039/c3nj01380dNew Journal of Chemistry383985-992NJCH

Enhanced nonlinear optical responses in donor-acceptor ionic complexes via photo induced energy transfer

10.1364/OE.18.025928Optics Express182525928-2593

In silico identification of potential inhibitors from rumex vesicarius against DPP4 of diabetes mellitus

Given the global epidemic of type-2 diabetes mellitus (T2DM) infection and the lack of suitable therapeutic options for diabetics, only a few medications have been licensed for the treatment of infected patients. Newer anti-diabetic medications with innovative mechanisms of action, as well as ways to reduce attrition in the early stages of drug development, are urgently needed. Rumex vesicarius was tested for antibacterial and antioxidant properties. Hence far, no in silico anti-diabetic study has been published against DPP4, so the goal of this paper is to report on the in silico docking of phytochemicals found in this plant against the target DPP4. On a series of known Rumex vesicaris compounds, in silico anti-T2DM lead prioritization was done. Using Autodock 4, the docking of DPP4 with 12 phytochemical compounds was done. Twelve compounds (Apigenin, Chrysophanol, Emodin, Physcion, Catechin, Epicatechin, Luteolin, quercetin, Rhein, tetramethylene sulfone, alloaromadendrene, and cis-Limonene oxide) were docked into DPP4 in the present study, and one compound, Chrysophanol, showed a high binding score (-8.99 PHE:559 may have a crucial function in the binding of these compounds

Huge enhancement of optical nonlinearities in coupled Au and Ag nanoparticles induced by conjugated polymers

10.1063/1.3675911Applied Physics Letters1002-APPL