Publication1

Readily accessible and shelf-stable 1,2,3-triazole and its analogues such as pyridotriazole, triazoloindole, benzotriazole, and thiadiazole exist in equilibrium with their ring-opened isomers, viz., diazo compounds. These ring-opened isomers could be trapped by various metal catalysts (e.g., Rh, Pd, Cu, Co, Ag, etc.) to generate the corresponding metal carbenoids with extrusion of nitrogen. As a consequence, these unique N-heterocycles facilitate access to a realm of N-containing complex structural motifs of biological importance through denitrogenative transformations such as transannulations, insertions, ylide formation, and rearrangements by trapping of the metal carbenoids with a diverse range of coupling partners (e.g., alkenes, alkynes, nitriles, carbo/heterocycles, X-H/C-X bonds, etc.). Hence, suitably substituted triazole derivatives have emerged as efficient surrogates of diazo compounds for the generation of reactive metal carbenoids during the past decades. In this comprehensive review, we aim to discuss in detail the remarkable advancement in their synthesis and synthetic applications.

This letter proposes a memory cell, denoted by 1F-1 T, consisting of a ferroelectric field-effect transistor (FeFET) cascaded with another current-limiting transistor (T). The transistor reduces the impact of drain current (Id) variations by limiting the on-state current in FeFET. The experimental data from our 28 nm high-k-metal-gate (HKMG) based FeFET calibrates and simulates the memory arrays. The simulation indicates a significant improvement in bit-line (BL) current (IBL) variation and the accuracy of vector-matrix multiplication of the 1F-1 T memory array. The system-level in-memory computing simulation with 1F-1T synapses shows an inference accuracy of 97.6% for the MNIST hand-written digits with multi-layer perceptron (MLP) neural networks.

27-hydroxycholesterol (27-HC) is a cholesterol metabolite and the first discovered endogenous selective estrogen receptor modulator (SERM) that has been shown to have proliferative and metastatic activity in breast cancer. However, whether 27-HC metabolite modulates the epigenetic signatures in breast cancer and its progression remains unclear. The current study, reports that 27-HC represses the expression of euchromatic histone lysine methyltransferase G9a, further reducing di-methylation at H3K9 in a subset of genes. We also observed reduced occupancy of ERα at the G9a promoter, indicating that 27-HC negatively regulates the ERα occupancy on the G9a promoter and functions as a transcriptional repressor. Further, ChIP-sequencing for the H3K9me2 mark has demonstrated that 27-HC treatment reduces the H3K9me2 mark on subset of genes linked to cancer progression, proliferation, and metastasis. We observed upregulation of these genes following 27-HC treatment which further confirms the loss of methylation at these genes. Immunohistochemical analysis with breast cancer patient tissues indicated a positive correlation between G9a expression and CYP7B1, a key enzyme of 27-HC catabolism. Overall, this study reports that 27-HC represses G9a expression via ERα and reduces the levels of H3K9me2 on a subset of genes, including the genes that aid in breast tumorigenesis and invasion further, increasing its expression in the breast cancer cells.

Two-dimensional (2D) nanomaterials like graphene, layered double hydroxides, etc., have received increasing attention owing to their unique properties imparted by their 2D structure. The newest member in this family is based on metal-organic frameworks (MOFs), which have been long known for their exceptional physicochemical properties—high surface area, tunable pore size, catalytic properties, etc., to list a few. 2D MOFs are promising materials for various applications as they combine the exciting properties of 2D materials and MOFs. Recently, they have been extensively used in biosensors by virtue of their enormous surface area and abundant, accessible active sites. In this review, we provide a synopsis of the recent progress in the field of 2D MOFs for sensor applications. Initially, the properties and synthesis techniques of 2D MOFs are briefly outlined with examples. Further, electrochemical and optical biosensors based on 2D MOFs are summarized, and the associated challenges are outlined.

Heterocyclic compounds are well-known for their use in the synthesis of drugs and drug intermediates. This review provides a systematic survey on the chemical synthesis of complex heterocyclic compounds containing multi-stereocentres using 3-arylidene-4-chromanones in the last two decades. Regioselective and stereoselective synthesis of complex heterocycles involving 3-arylidene-chromanones and 3-arylidene-thiochormanones are dealt under various reaction headings such as epoxidation, Michael addition, 1,3-dipolar cycloaddition, [3+2] and [4+2] cycloaddition, Diels-Alder reaction, sulfa-Michael/aldol cascade reactions, asymmetric synthesis employing bifunctional catalysts, chiral phase-transfer catalysts, chiral squaramide catalysts, etc. These synthetic highlights demonstrate the utility of 3-arylidene-4-chromanones and 3-arylidene-thiochormanones as versatile synthons for rapid assemblage of complex condensed heterocyles and spiro-fused heterocycles towards the development of pharmaceutically active compounds. A brief highlight on the synthetic methods of 3-arylidene-4-chromanone derivatives is also dealt. This review creates a platform for further improvement on the skeletal design of potential drug candidates.

Beamforming training or cell discovery (CD) is a fundamental procedure in millimeter wave communication systems in which the user detects the presence of a base station, acquires the identity of that base station, and finds suitable beamforming directions to establish the wireless link for the subsequent data transmission phase. We consider uniform planar array-based beamforming under both separable and non-separable configurations as it allows confined antenna placements and 3-D steering of beams. Our focus is to design the beamforming training phase and develop low-complexity receiver algorithms for the cell discovery procedure. By exploiting the sparse nature of the mm-wave channels and using an equivalent compressive sensing measurement model, we obtain analytical bounds for the cell detection probability in terms of the mutual coherence parameter of the resulting sensing matrix. Using mutually unbiased bases (MUB) from quantum information theory, we design CD schemes with low mutual coherence. Our design includes parameters that control the training phase duration, and we analytically characterize the relationship between the training duration and the corresponding mutual coherence value. We present detailed simulation studies using experimentally driven mm-wave channel simulators and show that our MUB based scheme gives superior detection performance when compared to the conventional beam sweeping based schemes and random beamforming schemes.

Milk adulteration is a common problem in developing countries, and it can lead to fatal diseases in humans. Despite several studies to identify different adulterants in milk samples, the effects of multiple adulterants remain unexplored. In this work, a three-dimensional (3D) paper-based microfluidic device is designed and fabricated to simultaneously detect multiple chemical adulterants in milk. This device comprises a top cover, a bottom cover, and a middle layer composed of transportation and a detection zone. By making cuts on the middle layer’s support, the device’s flow path is characterised by optimum and uniform velocity. For the first time, seven adulterants (urea, detergents, soap, starch, hydrogen peroxide, sodium-hydrogen-carbonate, and salt) are detected in the milk sample simultaneously with specificity evaluation and detailed color interference analysis. Only 1–2 mL of sample volume is required to detect 7 adulterants at one time. We have used only 10 μ L of the reagent’s volume for the colorimetric reaction and found the results within a few seconds. Observation reveals that the limit of detection (LOD) of the adulterants lies in the range between 0.05 % (vol./vol.) to 0.2 % (vol./vol.) using the colorimetric detection technique. The unknown quantity of the added adulterants is measured using the calibration curves obtained from the experiments results. The repeatability and reproducibility of the process, sensitivity, and the linear range of detection of the calibration curves and the statistical study of the color intensity data are thoroughly analysed herein. In any resource-limited setting, this simple, portable, and user-friendly 3D microfluidic device is expected to be used for testing liquid foods before consumption.

In materials research involving additive manufacturing (AM)-based techniques for the fabrication of a wide variety of materials, the latest trend at present is to focus largely on 3D printing (3DP) of nanoceramics, which at present is highly challenging, from both fundamental and industrial viewpoints in spite of the tremendous versatility offered by these techniques in terms of addressing design complexities. The two main reasons for the same are (1) low density and (2) poor mechanical properties of nanoceramic parts fabricated using 3DP techniques. The fundamental reason behind the two aforementioned features of 3DP-fabricated nanoceramic parts is the huge extent of microstructural inhomogeneity arising primarily due to variation in cooling rates during “point-by-point,” “line-by-line,” or “layer-by-layer” deposition methodology followed in 3DP techniques, leading to a number of defects in the microstructure. Moreover, the industrial application of nanoceramic parts manufactured using 3DP techniques is rather limited, primarily owing to the high manufacturing cost associated with these nanoceramic parts. Although, in the last 10 years, there has been a considerable volume of work on 3DP-based techniques for manufacturing ceramic parts with enhanced densities and improved mechanical properties; however, there is limited understanding on the correlation of microstructure of 3DP-fabriated nanoceramic components with the mechanical properties. On the other hand, in the recent decade, the “correlative” methodology of characterizing microstructures from micro- to nanoscale, involving a number of different structural and chemical characterization techniques, for the study of a number of defects ranging from the equilibrium point (or 0D) to nonequilibrium volume (or 3D) defects, has been hugely employed in a number of metallic materials. This has completely revolutionized the understanding of structure–property correlation and microstructural defects in these materials and paved a whole new dimension toward a systematic correlation of structure (ranging from bulk to nanoscale) to a wide range of properties in these materials. However, in the context of 3DP-fabricated nanoceramic parts, at present, there is hardly any report on understanding structure–property correlation using the aforementioned methodology. This chapter is aimed to review some of the most commonly used 3DP techniques for the fabrication of nanoceramics and provide an overview of the future perspectives, associated with the necessity toward developing a systematic structure–property correlation through “correlative” characterization methodology in these materials.

Irrational use of fossil fuels led to global warming and pollution. Therefore, the newer technologies should be sustainable and eco-friendly to combat climate change. In this context, supercapacitors (SCs) are demonstrated with carbon materials derived from natural biomaterials. The utilization of biomass-derived materials in energy storage not only converts biowaste material to value-added products but also reduces the production cost. Although SCs exhibit high power density, they are not considered a primary energy source due to their poor energy density. By taking advantage of the present work's asymmetric configuration, the operating voltage window and energy density of aqueous SCs are significantly enhanced. An asymmetric SC is developed by combining a porous 3D cubical-shaped Prussian blue (PB) decorated carbon derived from tamarind seeds (ACTS-800) (PB/ACTS-800) positive electrode with ACTS-800 negative electrode and aqueous 3 M KNO3 electrolyte. The resulting ACTS-800//PB/ACTS-800 (1:2) asymmetric SC demonstrated a broad electrochemical stable voltage window of 2.2 V in the aqueous medium. Impressively, a high energy density of 60 Wh/kg @ 551 W/kg realized is much superior to most of the carbon/carbon SCs operated in an aqueous medium.

We present an online motion planning algorithm (3D-OGSSE) for generating smooth, collision-free trajectories over multiple planning iterations for a 3-D agent operating in an unknown, obstacle-cluttered, 3-D environment. In each planning iteration, 3D-OGSSE constructs an obstacle-free region termed 'generalized sensed shape' based on the locally-sensed environment information and the notion of generalized shape. A collision-free path is computed by sampling points in the generalized sensed shape and is used to generate a smooth, time-parametrized trajectory by minimizing snap. The generated trajectory at every planning iteration is constrained to lie within generalized sensed shape, which ensures the agent maneuvers in locally obstacle-free space. As the agent reaches the boundary of the generalized sensed shape in a planning iteration, a re-plan is triggered by a receding horizon planning mechanism that also enables the initialization of the next planning iteration. We also present a theoretical guarantee for probabilistic completeness of the developed algorithm over the entire environment and for completely collision-free trajectory generation. We evaluate the proposed method in simulation on complex 3-D environments with varied obstacle-densities. Further, we also evaluate it in scenarios with sensor noise and constraints on the on-board sensor's field-of-view (FOV). We observe that each planning iteration computation takes $\sim 14$ milliseconds on a single thread of an Intel Core i5-8500 3.0 GHz CPU, which is significantly faster than several existing algorithms. In addition, we also observe 3D-OGSSE to be less conservative in complex scenarios such as narrow passages.

The famous combinatorial problem of Euler concerns an arrangement of 36 officers from six different regiments in a 6×6 square array. Each regiment consists of six officers each belonging to one of six ranks. The problem, originating from Saint Petersburg, requires that each row and each column of the array contains only one officer of a given rank and given regiment. Euler observed that such a configuration does not exist. In recent work, we constructed a solution to a quantum version of this problem assuming that the officers correspond to superpositions of quantum states. In this paper, we explain the solution which is based on a partition of 36 officers into nine groups, each with four elements. The corresponding quantum states are locally equivalent to maximally entangled two-qubit states, hence each quantum officer is represented by a superposition of at most 4 classical states. The entire quantum combinatorial design involves 9 Bell bases in nine complementary 4-dimensional subspaces.

Bulk-Acoustic-Wave (BAW)-technology-based oscillators have recently been introduced that combine a BAW resonator die with a CMOS circuit die containing oscillator and temperature compensation circuits [1]. In this work, we leverage the BAW technology to create a user programmable oscillator with attractive characteristics such as long-term reliability, miniaturization and low cost. Unlike low-frequency crystal/MEMS-based programmable resonators that require a fractional PLL to generate higher output frequencies [4-6], BAW resonators, due to a high resonant frequency (2.5GHz), allow programmability by making use of a Fractional Output Divider (FOD), as developed in this work.

We present a low-power and low jitter two-stage 2.46-4.92-GHz clock multiplier using a 38.4-MHz reference clock. The proposed clock multiplier implements an $8\times $ clock multiplication with a delay-locked loop and an edge combiner (EC) in the first stage. The regulated supply of the voltage-controlled delay line and EC within the delay-locked loop limits the first-stage clock multiplication voltage sensitivity. An in-depth phase noise analysis of the first stage with the proposed phase domain modeling and spur analysis in the EC helps low-power clock multiplier design. The first-stage output injection locks a pseudo-differential ring oscillator embedded in a frequency tracking loop, thereby achieving a $64\times $ - $128\times $ clock multiplication in the second stage. In collaboration with the simulated phase noise from sources, a system-level phase noise modeling defines the design specifications of the two stages for minimum output jitter in a given power budget. Fabricated in a 65-nm CMOS process, the first-stage clock multiplier achieves an integrated jitter 761 fsrms at 307.2 MHz while consuming 2.5 mW. The mismatch and offset-induced systematic jitter is calibrated, giving -53.4-dBc reference spur at the first-stage output. The second-stage injection-locked clock multiplier adds low random jitter to the first stage with total output jitter 825 fsrms at 4.92 GHz, -28.2-dBc reference spur, and 3-mW power consumption.

We present an integer-N phase-locked loop with a 5X output frequency range. The charge-pump current and voltage-controlled oscillator's current source are digitally reconfigured for an optimum PLL bandwidth with low output jitter across the 5X frequency range. Fabricated in indigenous SCL 180nm CMOS technology, the PLL multiplies the reference frequency 15-75MHz by seven and generates a 105-525MHz output frequency. It achieves an integrated jitter of 4ps and 32.2ps at 525MHz and l05MHz, respectively. The PLL dissipates 5.6mW and 3.6mW at 525MHz and l05MHz output frequencies while operating from 1.8V supply voltage.

In this paper, we demonstrate a wideband inloop phase modulation in an analog phase-locked loop for telemetry applications. PLLs have contradicting bandwidth requirements for low output reference spur and wideband inloop phase or frequency modulation. To overcome this challenge, we employ a two-point modulation at the input and output of the loop filter, thereby extending the modulation bandwidth. Using off-the-shelf PLL components, opamps, and passive components, a 2.25 GHz PLL with inloop phase modulation is analyzed and implemented on a PCB. The prototype is measured with an onboard 40 MHz crystal to have 340 fsrms integrated jitter and -70 dBc reference spur at the output. The prototype achieves a > 2 MHz -3 dB modulation bandwidth with small modulating amplitudes. An output phase modulation with modulation index m≤ 2 and modulation error Δm < 0.1 across 0.05-2.0 MHz frequency range is realized.

We present a two-stage cascaded clock multiplier with roughly constant energy consumption across 2.5-5.0GHz frequency range. The proposed clock multiplier consists of a reconfigurable delay-locked loop and edge combiner in the first stage while generating a 156.25-312.5MHz clock from 39.0625MHz reference clock frequency. An injection-locked clock multiplier with a frequency tracking loop in the second stage implements a 2.5-5.0 GHz output clock. The clock generation architecture is optimized for the clock multiplication ratio in the two stages and overall power consumption. Designed in TSMC 65nm CMOS process and characterized with post-layout simulations, the first-stage clock multiplier achieves an integrated jitter 1.396-0.607ps _{rms} across 156.25-312.5MHz frequency range at 1.15-2.82mW power consumption. The two-stage clock multiplier gives the total output jitter 1.5-0.9ps _{rms} across 2.5-5.0 GHz output frequency with 0.98-1.06mW/GHz power dissipation.

A supramolecular hydrogel with 3D self-shrinking, without any assistance, and a shape memory performance at room temperature is discovered from an unnatural amino acid derivative, i.e. fluorenylmethoxycarbonyl-l-β-phenylalanine, as a minimalistic model. The self-shrinking properties of this hydrogel can be explored for potential applications.

Bio-augmented systems based on methanotrophs are indispensable in curbing anthropogenic methane emissions from engineered landfills or dumpsites to curtail rising levels of greenhouse gases. Using a defined methanotroph culture immobilized on an inert material-based bio-carrier makes it possible to harness these methane emissions for creating value-added products, thus contributing to the circular bio-economy. The methane oxidation capacity of the model methanotroph Methylosarcina sp. LC-4, a prospective organism for biodiesel production using methane present in landfill gas, immobilized on several inert bio-carriers, was evaluated to identify a bio-carrier that provided optimum conditions for the process. Among the several bio-carriers evaluated, perlite and vermiculite were selected due to their high specific surface area and superior water-holding capacity, which result in the retention of nutrients and biomass and higher methane elimination capacity. While perlite showed high biomass holding capacity and methane transport, vermiculite supported a high growth of methanotrophs. LC-4 immobilized on perlite and vermiculite as the bio-carrier showed maximum methane elimination capacity (MEC) of 291.3 g m−2 day−1 and 155.5 g m−2 day−1, respectively. The low bed height of only 0.13 m and a short start-up period of 2–4 days are promising for use as alternate daily cover in a landfill. The recovered biomass had 12% (w/w) fatty acid methyl ester (FAME), with a high fraction of (∼85%) of C14–C18 saturated and monounsaturated fatty acids, suitable for biodiesel production. The combination of perlite and vermiculite increased MEC and FAME content levels. The current study demonstrated a new bio-augmented system designed with a pure methanotroph for methane elimination with a short start-up time and the valorization of the assimilated methane.