Recent developments in Chalcogenide phase change material-based nanophotonics.

There is now a deep interest in actively reconfigurable nanophotonics as they will enable the next generation of optical devices. Of the various alternatives being explored for reconfigurable nanophotonics, Chalcogenide phase change materials (PCMs) are considered highly promising owing to the nonvolatile nature of their phase change. Chalcogenide PCM nanophotonics can be broadly classified into integrated photonics (with guided wave light propagation) and Meta-optics (with free space light propagation).

Deep learning approach for inverse design of metasurfaces with a wider shape gamut.

While the large design degrees of freedom (DOFs) give metasurfaces a tremendous versatility, they make the inverse design challenging. Metasurface designers mostly rely on simple shapes and ordered placements, which restricts the achievable performance. We report a deep learning based inverse design flow that enables a fuller exploitation of the meta-atom shape.

A learning based approach for designing extended unit cell metagratings.

The possibility of arbitrary spatial control of incident wavefronts with the subwavelength resolution has driven research into dielectric optical metasurfaces in the last decade. The unit-cell based metasurface design approach that relies on a library of single element responses is known to result in reduced efficiency attributed to the inadequate accounting of the coupling effects between meta-atoms. Metasurfaces with extended unit-cells containing multiple resonators can improve design outcomes but their design requires extensive numerical computing and optimizations.

Deep learning: a new tool for photonic nanostructure design.

Early results have shown the potential of Deep Learning (DL) to disrupt the fields of optical inverse-design, particularly, the inverse design of nanostructures. In the last three years, the complexity of the optical nanostructure being designed and the sophistication of the employed DL methodology have steadily increased. This topical review comprehensively surveys DL based design examples from the nanophotonics literature.

Simultaneous quantification of N-butylthiophosphoric triamide and dicyandiamide in urea formulation by liquid chromatography with tandem mass spectrometry.

A new liquid chromatography with tandem mass spectrometry method employing a mixed-mode zwitterionic stationary phase was developed for simultaneous determination of urease inhibitor (N-butylthiophosphoric triamide) and nitrification inhibitor (dicyandiamide) in urea fertilizer. Molecular modeling based on density functional theory calculations was employed to provide an insight into the interaction mechanism of urea, dicyandiamide, and N-butylthiophosphoric triamide with zwitterionic stationary phase in chromatographic separation system. The detection of analytes was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode using positive electrospray ionization.

Highly Sensitive Refractive Index Sensors with Plasmonic Nanoantennas-Utilization of Optimal Spectral Detuning of Fano Resonances.

We analyze and optimize the performance of coupled plasmonic nanoantennas for refractive index sensing. The investigated structure supports a sub- and super-radiant mode that originates from the weak coupling of a dipolar and quadrupolar mode, resulting in a Fano-type spectral line shape. In our study, we vary the near-field coupling of the two modes and particularly examine the influence of the spectral detuning between them on the sensing performance.

Precision synthesis: designing hot spots over hot spots via selective gold deposition on silver octahedra edges.

A major challenge in plasmonic hot spot fabrication is to efficiently increase the hot spot volumes on single metal nanoparticles to generate stronger signals in plasmon-enhanced applications. Here, the synthesis of designer nanoparticles, where plasmonic-active Au nanodots are selectively deposited onto the edge/tip hot spot regions of Ag nanoparticles, is demonstrated using a two-step seed-mediated precision synthesis approach. Such a "hot spots over hot spots" strategy leads to an efficient enhancement of the plasmonic hot spot volumes on single Ag nanoparticles.

Encoding molecular information in plasmonic nanostructures for anti-counterfeiting applications.

We present the next generation covert plasmonic security labels based on Ag nanowire structures and their polarization dependent surface-enhanced Raman scattering (SERS) imaging. The security labels consist of Ag nanowires fabricated by two-photon lithography and thermal evaporation, where molecular probes of choice are deposited. Simulation and experimental results show that the SERS signals from the embedded molecules depend significantly on the polarization of the incident field.

Investigation of the possible role of Shankapushpi in the attenuation of ECT induced amnestic deficits.

Introduction: Shankapushpi (Evolvulus alsinoides and others) has received mention in traditional Indian writings as a potential enhancer of cognitive functioning. This study used an animal model to examine whether Shankapushpi improves learning and memory and attenuates anterograde and retrograde amnesia associated with electroconvulsive shocks (ECS).

Materials And Methods: Adult, male, Sprague Dawley rats (n=64) were treated with an aqueous extract of Shankapushpi or vehicle all through the 13-day study.

Printing colour at the optical diffraction limit.

The highest possible resolution for printed colour images is determined by the diffraction limit of visible light. To achieve this limit, individual colour elements (or pixels) with a pitch of 250 nm are required, translating into printed images at a resolution of ∼100,000 dots per inch (d.p.

ILPR G-quadruplexes formed in seconds demonstrate high mechanical stabilities.

The insulin linked polymorphism region (ILPR) is known to regulate transcription of the gene coding for insulin. The ILPR has guanine rich segments, suggesting that G quadruplexes may be responsible for this regulatory role. Using mechanical unfolding in a laser tweezers instrument and circular dichroism (CD) spectroscopy, we provide compelling evidence that highly stable parallel and antiparallel G quadruplex structures coexist in the predominant ILPR sequence of (ACAGGGGTGTGGGG)(2) at a physiologically relevant concentration of 100 mM KCl.

Structure-function relationship of novel X4 HIV-1 entry inhibitors - L- and D-arginine peptide-aminoglycoside conjugates.

We present the design, synthesis, anti-HIV-1 and mode of action of neomycin and neamine conjugated at specific sites to arginine 6- and 9-mers D- and L-arginine peptides (APACs). The d-APACs inhibit the infectivity of X4 HIV-1 strains by one or two orders of magnitude more potently than their respective L-APACs. D-arginine conjugates exhibit significantly higher affinity towards CXC chemokine receptor type 4 (CXCR4) than their L-arginine analogs, as determined by their inhibition of monoclonal anti-CXCR4 mAb 12G5 binding to cells and of stromal cell-derived factor 1alpha (SDF-1alpha)/CXCL12 induced cell migration.

Power scalable mid-infrared supercontinuum generation in ZBLAN fluoride fibers with up to 1.3 watts time-averaged power.

Mid-infrared supercontinuum (SC) extending to ~4.0 mum is generated with 1.3 W time-averaged power, the highest power to our knowledge, in ZBLAN (ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF.

Zero-n gap soliton.

Periodic structures consisting of alternating layers of positive-index and negative-index materials have a novel bandgap at the frequency at which the average refractive index is zero. We show that, in the presence of a Kerr nonlinearity, this zero-n gap can switch from low transmission to a perfectly transmitting state, forming a nonlinear resonance or gap soliton in the process. This zero-n gap soliton is omnidirectional, in contrast to the usual Bragg gap soliton of positive-index periodic structures.

Anti-calmodulin acridone derivatives modulate vinblastine resistance in multidrug resistant (MDR) cancer cells.

Multidrug resistance (MDR) is one of the main obstacles limiting the efficacy of chemotherapy treatment of tumors. Parent acridones 1A and 1B were prepared by the Ullmann reaction followed by cyclization and N-alkylation. N-(omega-Chloroalkyl) analogues were subjected to iodide catalyzed nucleophilic substitution reaction with secondary amines to get the compounds 3A-13A and 3B-13B, which enhanced the uptake of vinblastine in KBChR-8-5 cells to a greater extent (2.

Synthesis and chemical characterization of 2-methoxy-N(10)-substituted acridones needed to reverse vinblastine resistance in multidrug resistant (MDR) cancer cells.

In an attempt to find clinically useful modulators of multidrug resistance (MDR), a series of 19 N(10)-substituted-2-methoxyacridone analogues has been synthesized. 2-Methoxyacridone and its derivatives (1-19) were synthesized. Compound 1 was prepared by the Ullmann condensation of o-chlorobenzoic acid and p-anisidine followed by cyclization using polyphosphoric acid.