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The Pd(0) catalysed cyclisation reactions between tert-butyl propargyl carbonates and 2-aminotosyl benzamides or sulphonamides deliver 1,4-benzodiazepin-5-ones or sultam derivatives, key components of many biologically active compounds. But 2-amino benzamides/sulphonamides require propargyl carbonates substituted at acetylenic carbon to undergo the reaction resulting in the stereoselective formation of the said products.

Detection of bacterial colonies in water is a pressing issue in recent times owing to its implications on human health, leading to an urgent need for low cost, disposable sensors. In this work, we report a disposable impedimetric sensor for detection of total bacterial colonies present in water samples. The sensor consists of a polyaniline coated filter paper functionalized with a homo-bi functional crosslinker, glutaraldehyde. Prior to the functionalization step, two Ag electrodes are deposited on the filter paper using conductive silver paste. The aldehyde groups of glutaraldehyde bind with the amine functional groups present on bacterial cell wall resulting in a change in dielectric constant, and consequently, the capacitive effect between the two Ag electrodes. Also, bacterial metabolism affects the medium conductivity and in turn, the medium resistance changes. The combined effect of changes in capacitive effect as well as resistance is reflected as a change in AC impedance measured using a frequency response analyzer (FRA). E. coli and Pseudomonas aeruginosa bacteria are detected in PBS buffer up to ~ 500 cfu/mL. Testing is also carried out by spiking tap water and grey water with known concentrations of bacteria samples. The detection limits obtained are 500 – 1000 cfu/mL with a response time of ~ 20 minutes. The developed sensor provides rapid, moderately sensitive, cost-effective solution for detecting total bacterial load in water samples.

The Pd(0) catalysed cyclisation reactions between tert-butyl propargyl carbonates and 2-aminotosyl benzamides or sulphonamides deliver 1,4-benzodiazepin-5-ones or sultam derivatives, key components of many biologically active compounds. But 2-amino benzamides/sulphonamides require propargyl carbonates substituted at acetylenic carbon to undergo the reaction resulting in the stereoselective formation of the said products.

Ciliary oscillations driven by molecular motors cause fluid motion at micron scale. Stable oscillations require a substantial source of dissipation to balance the energy input of motors. Conventionally, it stems from external fluid. We show, in contrast, that external fluid friction is negligible compared to internal elastic stress through a simultaneous measurement of motion and flow field of an isolated and active Chlamydomonas cilium beating near the instability threshold. Consequently, internal friction emerges as the sole source of dissipation for ciliary oscillations. We combine these experimental insights with theoretical modeling of active filaments to show that an instability to oscillations takes place when active stresses are strain softening and shear thinning. Together, our results reveal a counterintuitive mechanism of ciliary beating and provide a general experimental and theoretical methodology to analyze other active filaments, both biological and synthetic ones., Comment: 29 pages, 8 figures

Cardiac biomarker detection helps in early diagnosis of cardiac syndromes. However, a rapid, cost-effective, reliable, and easy-to-use sensor is still unavailable. Herein, we report a disposable, label free, impedance-based biosensor for the detection of two common cardiac biomarkers, Myoglobin (Myo), and Myeloperoxidase (MPO). The sensor is fabricated on Whatman filter paper coated with a conducting polymer, polyaniline (PAni). The PAni-coated paper is functionalized with glutaraldehyde, a homo-bi functional crosslinker, prior to the covalent attachment of antibodies specific to each biomarker protein. Non-specific active regions of the sensor are blocked by treatment with bovine serum albumin. Conductive silver paste is used to define electrodes for AC impedance measurement on the PAni coated filter paper. Binding of the target protein (Myo or MPO) to the specific antibody changes the impedance between the electrodes; this is detected using AC impedance spectroscopy. The impedance is measured using a frequency response analyzer with an AC excitation voltage of 100 mV in the frequency range of 100 Hz–100 kHz. We can successfully detect Myo and MPO in buffer solution within the concentration range of 100 ng/mL– $50~\mu \text{g}$ /mL. Detection limit obtained for these cardiac biomarkers spiked in human serum is $1~\mu \text{g}$ /mL. Further blocking using human serum improves the lower detection limit to 500 ng/mL. The developed biosensor uses inexpensive materials and fabrication techniques, detects cardiac biomarkers in clinically relevant concentrations rapidly (i.e., within 20 mins), and can be disposed in an environment friendly manner, thus making the sensor suitable for diagnostic applications.

A disposable filter paper based electronic tongue using different conducting polymers is developed in this work. Sensors were prepared using Whatman filter papers of dimensions 6 mm × 5 mm coated with different conducting polymers (polyaniline and polypyrrole, both in doped and de-doped form). Two Ag electrodes were deposited with a separation of 4 mm for AC impedance spectroscopic measurements in the frequency range of 10 Hz – 10 kHz with a 100 mV excitation voltage. The developed sensor was subjected to different concentrations of four basic tastants i.e., salty, sweet, sour and umami. The sensitivity of the sensor was found to be better than the human tongue for all the different tastants. The sensors were also used to differentiate between different water samples and fruit juices, with a promising potential for use in food quality monitoring. Use of principal component analysis on the impedance data aided in formation of clusters, thus distinguishing different types of water samples.

Lab-on-chip devices have become inevitable in the field of point of care application owing to the requirement of low sample volume, rapid detection, easy use, and low cost. In this chapter, we discuss the transduction techniques that find application in the development of lab-on-chip devices ie, optical, electrochemical, thermal, and acoustic wave-based transduction, along with a special type of lab-on-chip devices based on paper microfluidics. The approach of this chapter is to discuss the types of on-chip devices from the point of view of the working principle, followed by some highlights of recent advances in the development of such devices.

This paper presents the hardware realization and performance study of fractional inductors of order 0

The present work reports the realization of an analog fractional-order phase-locked loop FPLL using a fractional capacitor. The expressions for bandwidth, capture range, and lock range of the FPLL have been derived analytically and then compared with the experimental observations using LM565 IC. It has been observed that bandwidth and capture range can be extended by using FPLL. It has also been found that FPLL can provide faster response and lower phase error at the time of switching compared to its integer-order counterpart. Copyright © 2014 John Wiley & Sons, Ltd.

In this paper, packaging issue of a single-component fractional order element (FOE) is presented. Packaging is required for better longevity and miniaturization of dimensions. In addition, it helps in fabrication of a single-component FOE as a discrete element similar to the existing passive circuit elements. An alternate electrode (platinized silicon) for fabricating single-component FOE other than the existing copper electrode has been proposed for the first time in this paper. A comparative analysis has been carried out between the performances of packaged FOEs using copper and platinized silicon electrodes.

The objectives of this work are (i) to verify experimentally the theoretical claim that neither Riemann–Liouville nor Caputo fractional derivative can be used to predict the time response of fractional order systems without proper correction for the system’s past history in terms of an initialization function and (ii) to study quantitatively how the error incurred due to ignoring initialization depends on the nature of the past history and the system parameters. The entire analysis is restricted to a special class of single input single output linear time invariant fractional order system which can be realized by a simple electrical circuit consisting of a resistance and a fractance in series. This work involves two different realizations of fractances or constant phase elements whose characteristic parameters are first determined based on their respective impedance frequency responses and then used to simulate the time responses of the circuit with the input same as the one used for experimentation using a numerical method for two cases: (i) taking past history into account and (ii) without taking past history into account. Thereafter, an integral square error criterion is presented and variation of the same is studied with respect to system parameters and nature of the history function to have a relative idea of how much partial past history in the absence of a complete one should suffice in practical applications.

A single-component fractional order element (FOE) is realised and its performance is compared with the conventional FOEs such as cross resistance-capacitance (RC) ladder network and domino ladder network in the analogue domain. The single-component FOE is a capacitive-type probe coated with a porous film of poly-methyl-methacrylate (PMMA) and is dipped in polarisable medium. The fractional exponent of the fabricated single-component FOE and domino ladder can be varied between 0 and 1 whereas that of cross RC ladder realised in this work is 1/2. The performance of fractional order integrator (FOI) using these FOEs is studied in both frequency and time domain by simulation and experimentation. A comparative analysis of the performance of FOI is carried out.