Broadband GaAsSb Nanowire Array Photodetectors for Filter-Free Multispectral Imaging.

Highly compact, filter-free multispectral photodetectors have important applications in biological imaging, face recognition, and remote sensing. In this work, we demonstrate room-temperature wavelength-selective multipixel photodetectors based on GaAs0.94Sb0.06 nanowire arrays grown by metalorganic vapor phase epitaxy, providing more than 10 light detection channels covering both visible and near-infrared ranges without using any optical filters. The nanowire array geometry-related tunable spectral photoresponse has been demonstrated both theoretically and experimentally and shown to be originated from the strong and tunable resonance modes that are supported in the GaAsSb array nanowires. High responsivity and detectivity (up to 44.9 A/W and 1.2 × 1012 cm √Hz/W at 1 V, respectively) were obtained from the array photodetectors, enabling high-resolution RGB color imaging by applying such a nanowire array based single pixel imager. The results indicate that our filter-free wavelength-selective GaAsSb nanowire array photodetectors are promising candidates for the development of future high-quality multispectral imagers.

A new bound on polymer quantization via an opto-mechanical setup.

The existence of a minimal measurable length as a characteristic length in the Planck scale is one of the main features of quantum gravity and has been widely explored in the context. Various different deformations of spacetime have been employed successfully for the purpose. However, polymer quantization approach is a relatively new and dynamic field towards the quantum gravity phenomenology, which emerges from the symmetric sector of the loop quantum gravity. In this article, we extend the standard ideas of polymer quantization to find a new and tighter bound on the polymer deformation parameter. Our protocol relies on an opto-mechanical experimental setup that was originally proposed to explore some interesting phenomena by embedding the minimal length into the standard canonical commutation relation. We extend this scheme to probe the polymer length deformed canonical commutation relation of the center of mass mode of a mechanical oscillator with a mass around the Planck scale. The method utilizes the novelty of exchanging the relevant mechanical information with a high intensity optical pulse inside an optical cavity. We also demonstrate that our proposal is within the reach of the current technologies and, thus, it could uncover a decent realization of quantum gravitational phenomena thorough a simple table-top experiment.

Fighting Diabetes: Lessons from Xenotransplantation and Nanomedicine.

Increasing incidence of diabetes and shortage of specific beta cells, hormonal switches like that of delta and PP cells of the islets for transplantation, have forced the scientific community to look for alternative sources through xenotransplantation and nanomedicine. The Edmonton protocol of islet transplantation has shown proof of principle of long term survival of islets in type I diabetic patients, leading to insulin prick free life. Copious volume of literature exists on the use of mammalian islets, especially of porcine origin for diabetes reversal in humans with follow-up studies upto 10 yrs. There is an obvious lack of pre-clinical results and data in the pig-to-primate model. The difficulty is in reproducing regularly the successful porcine islet isolation. Although some of the parameters have been taken, making xenotransplantation an attractive and viable alternative therapy. However, scarcity of islets is the main hurdle in the success of islet transplantation programs. Since the islet cell receptor and the insulin molecule have remained conserved throughout the evolution of vertebrates, we reviewed islet studies from other vertebrates especially, jawless fish, cartilaginous as well as bony fishes and chick islets. The similarities of chick B islets with human islets in terms of Streptozotocin insensitivity and retention of glucose responsiveness by new born chick islets tempted us to hypothesize the use of fish and chick islets as alternative sources for transplantation to reverse experimental diabetes. Since ontogeny recapitulates phylogeny, the islets recovered from lower vertebrates are likely to be less immunogenic and may open possibility of using them without immunosuppression. Complementing xenotransplantation, nanotechnology offers an excellent module for addressing the diabetes problem from detection and treatment points of view. This review attempts to throw some light on both these approaches for an effective management and cure of diabetes.