Confocal Spectroscopy to Study Dimerization,Oligomerization and Aggregation of Proteins: A Practical Guide

Protein self-association is a key feature that can modulate the physiological role of proteins or lead to deleterious effects when uncontrolled. Protein oligomerization is a simple way to modify the activity of a protein, as the modulation of binding interfaces allows for self-activation or inhibition, or variation in the selectivity of binding partners. As such, dimerization and higher order oligomerization is a common feature in signaling proteins, for example, and more than 70% of enzymes have the potential to self-associate. On the other hand, protein aggregation can overcome the regulatory mechanisms of the cell and can have disastrous physiological effects. This is the case in a number of neurodegenerative diseases, where proteins, due to mutation or dysregulation later in life, start polymerizing and often fibrillate, leading to the creation of protein inclusion bodies in cells. Dimerization, well-defined oligomerization and random aggregation are often difficult to differentiate and characterize experimentally. Single molecule “counting” methods are particularly well suited to the study of self-oligomerization as they allow observation and quantification of behaviors in heterogeneous conditions. However, the extreme dilution of samples often causes weak complexes to dissociate, and rare events can be overlooked. Here, we discuss a straightforward alternative where the principles of single molecule detection are used at higher protein concentrations to quantify oligomers and aggregates in a background of monomers. We propose a practical guide for the use of confocal spectroscopy to quantify protein oligomerization status and also discuss about its use in monitoring changes in protein aggregation in drug screening assays.     

Mitigating Chromatic Dispersion with Hybrid Optical Metasurfaces

Metasurfaces control various properties of light via scattering across a large number of subwavelength‐spaced nanostructures. Although metasurfaces appear to be ideal photonic platforms for realizing and designing miniaturized devices, their chromatic aberrations have hindered the large‐scale deployment of this technology in numerous applications. Wavelength‐dependent diffraction and resonant scattering effects usually limit their working operation wavelengths. In refractive optics, chromatic dispersion is a significant problem and is generally treated by cascading multiple lenses into achromatic doublets, triplets, and so on. Recently, broadband achromatic metalenses in the visible have been proposed to circumvent chromatic aberration but their throughput efficiency is still limited. Here, the dispersion of refractive components is corrected by leveraging the inherent dispersion of metasurfaces. Hybrid refractive‐metasurface devices, with nondispersive refraction in the visible, are experimentally demonstrated. The dispersion of this hybrid component, characterized by using a Fourier plane imaging microscopy setup, is essentially achromatic over about 150 nm in the visible. Broadband focusing with composite plano‐convex metasurface lenses is also proposed. These devices could find applications in numerous consumer optics, augmented reality components, and all applications including imaging for which monochromatic performance is not sufficient.     

Keyword search on form results

In recent years there has been a good deal of research in the area of keyword search on structured and semistructured data. Most of this body of work has a significant limitation in the context of enterprise data, since it ignores the application code that has often been carefully designed to present data in a meaningful fashion to users. In this work, we consider how to perform keyword search on enterprise applications, which provide a number of forms that can take parameters; parameters may be explicit, or implicit such as the identifier of the user. In the context of such applications, the goal of keyword search is, given a set of keywords, to retrieve forms along with corresponding parameter values, such that result of each retrieved form executed on the corresponding retrieved parameter values will contain the specified keywords. Some earlier work in this area was based on creating keyword indices on form results, but there are problems in maintaining such indices in the face of updates. In contrast, we propose techniques based on creating inverted SQL queries from the SQL queries in the forms. Unlike earlier work, our techniques do not require any special purpose indices and instead make use of standard text indices supported by most database systems. We have implemented our techniques and show that keyword search can run at reasonable speeds even on large databases with a significant number of forms.     

Adaptive multi-dimensional filters

In the present work, adaptive multi-dimensional filtering technique is proposed, which in addition to numerical stabilization, results in significant reduction of computational efforts. A criterion for adaptive filtering is proposed with algorithm provided. A new buffer domain technique based on adaptive filtering is developed and demonstrated for flow past a stationary cylinder for different Reynolds numbers. This technique also allows calculations in a reduced domain, showing another use of adaptive filtering. Rotary oscillation of a circular cylinder at different forcing parameters show excellent match with results in the literature, demonstrating potential benefits of adaptive filtering.     

Construction of a secure and efficient content key distribution framework for DRM systems

Recent advances in networks and digital technology have provided many user-friendly environments such as telemedicine, e-banking, e-content, and e-commerce. It has revolutionized the multimedia industry and made it accessible anytime and anywhere. However, its limitation also appeared in digital content piracy, which is more prevalent nowadays. Digital rights management (DRM) systems were developed to control the illegal spreading of digital content. Protocols are being developed to enable effective and secure communication in DRM systems. As security and efficiency are essential parameters, the approach should be two birds with one stone; i.e., the protocol should achieve efficiency and security together. Our investigation identified that secure mechanisms either have increased computation/communication overhead or fail to meet specified security criteria when discussing efficient content key delivery mechanisms. So, an efficient protocol design with the right security attributes is required. We have worked on designing a content delivery mechanism keeping in mind the desirable attribute of security and without decreasing overhead. The suggested solution targets “two birds with one stone.” We proved the security of the scheme in the random oracle model. We verify the security against active attacks using the formal simulation tool AVISPA. Detailed analysis is performed for the evaluation of computational and communication overhead. The comparative study is also presented to understand the gains in efficiency and security.     

Recent advances in the approaches to recover rare earths and precious metals from E-waste: A mini-review

In the present day, with the rapid rate of advancements in technology, gadgets become obsolete very fast. The chase to keep up with the latest technologies diminishes the gadget's lifespan considerably. Consequently, they are discarded within a short time after their production, resulting in electronic waste (E-waste) being the fastest growing waste stream globally, with an annual production rate of 2.44 million short tonnes. The metals present in such E-waste provide several attractive properties, rendering them crucial in several applications as components of electronic and electrical devices. The major roadblock faced by mankind today is an effective technology with high recovery, low cost, and minimal environmental impact to recycle such electronic waste. In this mini-review, we elucidate the various recycling routes for metal extraction from waste and recent advances in the same. We have attempted to highlight the recent trends adopted by various researchers to recycle and extract valuable metals and rare earths from E-waste. Finally, the challenges and prospects in the extraction of rare earths and precious metals for E-waste research have been clearly brought out and suggestions have been made for future work.