Department of Chemistry

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

&nbsp;

IIT Palakkad

Fast normalized covariance based similarity measure for fractal video compression with quadtree partitioning is proposed in this paper. To increase the speed of fractal encoding, a simplified expression of covariance between range and overlapped domain blocks within a search window is implemented in frequency domain. All the covariance coefficients are normalized by using standard deviation of overlapped domain blocks and these are efficiently calculated in one computation by using two different approaches, namely, FFT based and sum table based. Results of these two approaches are compared and they are almost equal to each other in all aspects, except the memory requirement. Based on proposed simplified similarity measure, gray level transformation parameters are computationally modified and isometry transformations are performed using rotation/reflection properties of IFFT. Quadtree decompositions are used for the partitions of larger size of range block, that is, 16 x 16, which is based on target level of motion, compensated prediction error. Experimental result shows that proposed method can increase the encoding speed and compression ratio by 66.49\% and 9.58\%, respectively, as compared to NHEXS method with increase in PSNR by 0.41 dB. Compared to H.264, proposed method can save 20\% of compression time with marginal variation in PSNR and compression ratio.

World University root node

HELIX

Fast Normalized Covariance based Similarity Measure for Fractal Video Compression with Quadtree Partitioning

The synthesis, photophysics and biological investigation of fluorescent 4-amino-1,8-naphthalimide Tröger's bases (TB-1-TB-3) and a new Tröger's base p-cymene-Ru(ii)-curcumin organometallic conjugate (TB-Ru-Cur) are described; these compounds showed fast cellular uptake and displayed good luminescence and cytotoxicity against cervical cancer cells. © 2018 The Royal Society of Chemistry.

Fulltext

Chemical Communications

Synthesis, structural characterisation and antiproliferative activity of a new fluorescent 4-amino-1,8-naphthalimide Tröger's base-Ru(ii)-curcumin organometallic conjugate

The first Ru(II)-catalyzed arylation of substrates without a directing group was recently developed. Remarkably, this process only worked in the presence of a benzoate additive, found to be crucial for the oxidative addition step at Ru(II). However, the exact mode of action of the benzoate was unknown. Herein, we disclose a mechanistic study that elucidates the key role of the benzoate salt in the C-H arylation of fluoroarenes with aryl halides. Through a combination of rationally designed stoichiometric experiments and DFT studies, we demonstrate that the aryl-Ru(II) species arising from initial C-H activation of the fluoroarene undergoes cyclometalation with the benzoate to generate an anionic Ru(II) intermediate. The enhanced lability of this intermediate, coupled with the electron-rich anionic Ru(II) metal center renders the oxidative addition of the aryl halide accessible. The role of an additional (NMe4)OC(CF3)3 additive in facilitating the overall arylation process is also shown to be linked to a shift in the C-H pre-equilibrium associated with benzoate cyclometalation. © 2018 American Chemical Society.

Journal of the American Chemical Society

Benzoate Cyclometalation Enables Oxidative Addition of Haloarenes at a Ru(II) Center

Treatment of a dirhodium analogue of pentaborane(9), [(Cp*Rh)2B3H7] (nido-1; Cp* = η5-C5Me5), with [Fe2(CO)9] at room temperature led to the formation of [(Cp*Rh)2Fe(CO)3(µ-CO)B3H2Cl] (2) and the metal-rich metallaborane [(Cp*Rh)2Fe(CO)3Fe(CO)2(µ-CO)2B2H2] (3). When the same reaction was carried out at moderate temperature, two metal-rich metallaboranes, [(Cp*Rh)3Fe(CO)2(µ3-CO)2B2HX] 4 (X = H) and 5 (X = Cl) and a heterometallic µ9-boride cluster, [(Cp*Rh)3(RhCO)3Fe(CO)3(µ-CO)3B3H2] (6), were obtained. Compounds 4 and 5 can be viewed as cubane clusters with 62 cluster valence electrons (cves) and five metal–metal bonds. In another reaction, the treatment of nido-1 with [Mn2(CO)10] yielded the heterometallic µ9-boride cluster [(Cp*Rh)3Rh(CO)2{Mn(CO)3}2B4H3] (7). The cluster cores of both 6 and 7 are comprised of tricapped trigonal prisms containing a µ9-B atom bonded to seven/six metals and two/three boron atoms, respectively. All the new compounds have been characterized by mass spectrometry, IR, 1H, 11B{1H} and 13C{1H} NMR spectroscopy and X-ray crystallographic analysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

European Journal of Inorganic Chemistry

Metal‐Rich Metallaboranes: Structures and Geometries of Heterometallic µ9‐Boride Clusters

Protein S-palmitoylation refers to a post-translational modification (PTM) wherein palmitic acid, a 16-carbon long saturated fatty acid gets covalently attached to Cys sidechain of a protein. It has been known to the literature for almost 50 years and in general, this PTM is believed to facilitate membrane attachments of proteins for the obvious hydrophobicity of the palmitoyl group. But after the discovery of the protein palmitoyl acyltransferases (PATs, also known as DHHC-PATs), a major paradigm shift has been observed in the field of protein S-palmitoylation. A family of 23 mammalian DHHC-PATs has been identified and the majority of them are associated with many human diseases spanning from neuropsychiatric diseases to cancers. Novel unique and essential role of DHHC-mediated protein S-palmitoylation has been revealed apart from its membrane trafficking role. Biomedical importance of DHHCs has also been reiterated with small molecule inhibitors for DHHCs as well as in DHHC-knockout mice or mouse Xenograft models. In this review, we present recent advances in the field of protein S-palmitoylation and the involvement of individual DHHC isoforms in human diseases. In addition, the recent development of the analytical tools to study S-palmitoylation and their inhibitors are discussed in detail. We also highlight the issues that need to be addressed in detail to further develop our understanding on protein S-palmitoylation and strongly believe that pharmacological modulation of DHHC-mediated protein S-palmitoylation has a massive potential to emerge as a novel therapeutic strategy for human diseases. It will not be surprising if reversible protein S-palmitoylation prove to be an indispensable PTM that regulates a host of cellular processes, just like protein phosphorylation or ubiquitination. © 2018 Elsevier GmbH

European Journal of Cell Biology

Emerging Roles of DHHC-mediated Protein S-palmitoylation in Physiological and Pathophysiological Context

A novel electrochemical aptasensing transducer platform has been developed based on carbon nanotube (CNT)-V2O5-chitosan (CS) nanocomposites modified screen printed carbon electrode (SPCE) for the detection of ciprofloxacin. Using CNT-V2O5-CS/SPCE as the basal electrode transducer platform for the immobilization of the single-stranded DNA aptamer, and the electrochemical impedance spectroscopy (EIS) was selected for quantitative detection of ciprofloxacin (CIP). This aptasensor combines the biocompatibility of V2O5 nanoparticles, the efficient electron transfer capability of multiwalled CNTs, the effective film-forming strength of CS and the portability of SPCE. Under optimized experimental parameters, the developed aptasensor exhibited a dynamic range from 0.5 to 64.0 ng mL−1, where the linearity was between 0.5 to 8.0 ng mL−1 and the limit of detection (LOD) was 0.5 ng mL−1 of CIP. Furthermore, it showed good selectivity to CIP. For practical application, the aptasensor performance was verified in spiked milk samples and the acceptable recovery percentage of 94.50-97.87% (%RSD = 4.38, n = 3) was obtained. © 2018 Elsevier B.V.

Sensors and Actuators, B: Chemical

Disposable electrochemical aptasensor based on carbon nanotubes- V2O5-chitosan nanocomposite for detection of ciprofloxacin

Ruthenium-catalysis enabled the C-5 selective C-H oxygenation of naphthoquinones, and also sets the stage for the site-selective introduction of a hydroxyl group into anthraquinones. A-ring modified naphthoquinoidal compounds represent an important class of bioactive quinones for which the present study encompasses the first C-H oxygenation strategy by weak O-coordination. © 2018 The Royal Society of Chemistry.

Ruthenium-catalyzed C-H oxygenation of quinones by weak O-coordination for potent trypanocidal agents

This work demonstrates the development of electrochemical aptasensor using ochratoxin A (OTA) aptamers. Different aptamer coupling strategies were tested using polythiophene-carboxylic acid (PT3C) and polypyrrole-3-carboxylic acid (PP3C). The best sensitivity was recorded by polythiophene-3-carboxylic acid (PT3C) on screen-printed carbon electrode (SPCE) to attain the direct detection of OTA. The quantification of OTA was achieved by using electrochemical impedance spectroscopy. A good dynamic range 0.125–2.5 ng ml−1 was obtained for OTA with limit of detection (LOD) 0.125 ng ml−1 and Limit of quantification (LOQ) 0.3 ng ml−1 respectively. The good reproducibility was recorded with RSD% of 3.68. The obtained straight line equation was y = 0.4061 × + 1.03, r = 0.99. For real sample applications, the developed aptasensors were demonstrated in coffee samples. The aptasensor displayed good recovery values in the range 88–89%, thus exhibited the effectiveness of proposed aptasensor for such complex matrices. © 2018 Elsevier B.V.

Talanta

Label free aptasensor for ochratoxin A detection using polythiophene-3-carboxylic acid

Antibiotic discovery has experienced a severe slowdown in terms of discovery of new candidates. In vitro screening methods using phospholipids to model the bacterial membrane provide a route to identify molecules that specifically disrupt bacterial membranes causing cell death. Thanks to the electrically insulating properties of the major component of the cell membrane, phospholipids, electronic devices are highly suitable transducers of membrane disruption. The organic electrochemical transistor (OECT) is a highly sensitive ion-to-electron converter. Here, the OECT is used as a transducer of the permeability of a lipid monolayer (ML) at a liquid:liquid interface, designed to read out changes in ion flux caused by compounds that interact with, and disrupt, lipid assembly. This concept is illustrated using the well-documented antibiotic Polymixin B and the highly sensitive quantitation of permeability of the lipid ML induced by two novel recently described antibacterial amine-based oligothioetheramides is shown, highlighting molecular scale differences in their disruption capabilities. It is anticipated that this platform has the potential to play a role in front-line antimicrobial compound design and characterization thanks to the compatibility of semiconductor microfabrication technology with high-throughput readouts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Advanced Materials

Biomimetic Electronic Devices for Measuring Bacterial Membrane Disruption

Results of our study on ultrafast electron transfer (eT) dynamics from coumarins (coumarin-1, coumarin-480, and coumarin-153) incarcerated within octa acid (OA) capsules as electron donors to methyl viologen dissolved in water as acceptor are presented. Upon photoexcitation, coumarin inside the OA capsule transfers an electron to the acceptor electrostatically attached to the capsule leading to a long-lived radical-ion pair separated by the OA capsular wall. This charge-separated state returns to the neutral ground state via back electron transfer on the nanosecond time scale. This system allows for ultrafast electron transfer processes through a molecular wall from the apolar capsular interior to the highly polar (aqueous) environment on the femtosecond time scale. Employing femtosecond transient absorption spectroscopy, distinct rates of both forward (1-25 ps) and backward eT (700-1200 ps) processes were measured. Further understanding of the energetics is provided using Rehm-Weller analysis for the investigated photoinduced eT reactions. The results provide the rates of the eT across a molecular wall, akin to an isotropic solution, depending on the standard free energy of the reaction. The insights from this work could be utilized in the future design of efficient electron transfer processes across interfaces separating apolar and polar environments. © 2017 American Chemical Society.