Hybrid Metallodielectric Metasurfaces for Sensing

We have fabricated metasurfaces that combine silicon resonators with aluminium disks. While the latter produce strong near-field enhancement, the former support optical resonances that can be used to obtain well-controlled far-field signatures

Stealthy Hyperuniform Surface Structures for Efficiency Enhancement of Organic Solar Cells

Low absorption in the thin active layer of conventional organic solar cells limits their power conversion efficiency. Structured surface layers are a common approach to diffracting incoming light, thus elongating its path through the active layer, thereby increasing the probability of absorption and hence the power conversion efficiency. While standard periodic structures diffract light into discrete angles, making them optimal only for specific wavelengths, random structures induce broadband, but nontailorable diffraction. Thus, instead, a stealthy hyperuniform structure, designed to exhibit beneficial diffraction properties is implemented: it directs the light into a predefined range of higher angles, prevents diffraction into small angles, and is thus ideal for a strong active path length enhancement. After numerical optimization of the feature height and diameter, the stealthy hyperuniform structure is fabricated in silicon by electron beam lithography and subsequently transferred into a transparent polymer via replica molding. Experimental diffraction images reveal a circular symmetric spectrum, inducing diffraction independent of the azimuthal angle and polarization of the incident light. The application of the stealthy hyperuniform structure on a poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione)]:3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d’]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene organic solar cell leads to a sharp increase in current density and power conversion efficiency

Fabrication of alloyed plasmonic nanostructures

We have fabricated homogeneous thin films of an alloy of Au and Ag, by annealing two consecutive deposited layers of Au and Ag. We have also successfully fabricated nanodisks and nanorods made of AuAg alloys by annealing the nanostructures at 300 degrees C for 5 hours showing that the nanostructures retain their shape after annealing. The developed process additionally enables tailoring the properties of the plasmonic material, providing a supplementary degree of freedom and enables the fabrication of a variety of plasmonic nanostructures with the properties of the request

Hybrid Metal-Dielectric Metasurfaces for Refractive Index Sensing

Hybrid metal-dielectric nanostructures have recently gained prominence because they combine strong field enhancement of plasmonic metals and the several low-loss radiation channels of dielectric resonators, which are qualities pertaining to the best of both worlds. In this work, an array of such hybrid nanoantennas is successfully fabricated over a large area and utilized for bulk refractive index sensing with a sensitivity of 208 nm/RIU. Each nanoantenna combines a Si cylinder with an Al disk, separated by a SiO2 spacer. Its optical response is analyzed in detail using the multipoles supported by its subparts and their mutual coupling. The nanoantenna is further modified experimentally with an undercut in the SiO2 region to increase the interaction of the electric field with the background medium, which augments the sensitivity to 245 nm/RIU. A detailed multipole analysis of the hybrid nanoantenna supports our experimental findings

Emergence of oriental theileriosis in cattle and its transmission through Rhipicephalus (Boophilus) microplus in Assam, India

Aim: The aim of the present study was to investigate the presence of Theileria in blood samples of crossbred and indigenous adult cows raised under unorganized small scale farming system in a Babesia and Anaplasma endemic geographical area from Assam, India and to see its transmission through Rhipicephalus (Boophilus) microplus ticks. Materials and Methods: For the present study, 57 clinical cases of cattle suspected to be of hemoparasitic infections were taken into consideration. The parasites were identified based on morphology in giemsa stained blood smear followed by polymerase chain reaction (PCR). Sera samples were tested for T. annulata antibodies in plate and Dot-ELISA. PCR was also conducted in eggs of Rhipicephalus (Boophilus) microplus tick collected from a Theileria orientalis positive animal. Results: PCR amplified 1124, 776, and 160 bp DNA fragments of B. bigemina (64.91%),T. orientalis(21.05%) and A. marginale (14.03%), respectively. This assay further conducted in 12 T. orientalis positive blood samples with primers of Buffeli, Chitose, and Ikeda variants of T. orientalis showed 3 samples positive to Ikeda type and none for Buffeli and Chitose. Babesia bovis and Theileria annulata specific primers also did not amplify any fragment during the PCR assay of the blood samples. Further, all sera samples tested negative to T. annulata antibodies in Plate and Dot-ELISA. PCR conducted in eggs of R (B).microplus tick collected from a T. orientalis positive animal revealed presence of the parasite DNA. Gradual improvement in physical condition leading to complete recovery in 10 out of 12 T. orientalis infected clinical cases treated with buparvaquone(at 2.5mg/kg.b.wt I/M) was the feedback obtained from field veterinarians and the cattle owners. Conclusion: The present investigation represents the first report of occurrence of T. orientalis in cattle of Assam with involvement of pathogenic Ikeda strain in clinical outbreaks and its possible natural transmission by R (B). microplus through the transovarian mode

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Not Available: Keratoconjunctivitis in sheep causes severe ocular irritation thereby reducing the production performance thus causing economic loss to the farmers. Bacterial cause of keratoconjunctivitis in sheep may be due to Listeria monocytogenes, Moraxella ovis, Mycoplasma conjunctivae, etc. An investigation carried out at Tirupathur, Sivagangai district, Tamil Nadu, India revealed keratoconjunctivitis in sheep (population 100 animals). Isolation and identification of eye swabs from ailing animals (n = 5) showed that the bacteria was Moraxella sp. Polymerase chain reaction (PCR) of the isolate was positive for Moraxella sp. Antimicrobial sensitivity testing of the isolate showed that it was sensitive to all antibiotics used in the study. This study reports the presence of Moraxella sp. infection in sheep warranting further studies to know the exact status of this organism so as to prevent keratoconjunctivitis in sheep.Not Availabl

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