Pixel size and pitch measurements of liquid crystal spatial light modulator by optical diffraction

We present a simple technique for the determination of pixel size and pitch of liquid crystal (LC) based spatial light modulator (SLM). The proposed method is based on optical diffraction from pixelated LC panel that has been modeled as a two-dimensional array of rectangular apertures. A novel yet simple, two-plane measurement technique is implemented to circumvent the difficulty in absolute distance measurement. Experimental results are presented for electrically addressed twisted nematic LC-SLM removed from the display projector.     

Probing the intestinal α-glucosidase enzyme specificities of starch-digesting maltase-glucoamylase and sucrase-isomaltase: synthesis and inhibitory properties of 3'- and 5'-maltose-extended de-O-sulfonated ponkoranol

The synthesis and glucosidase inhibitory activities of two C-3'- and C-5'-β-maltose-extended analogues of the naturally occurring sulfonium-ion inhibitor, de-O-sulfonated ponkoranol, are described. The compounds are designed to test the specificity towards four intestinal glycoside hydrolase family 31 (GH31) enzyme activities, responsible for the hydrolysis of terminal starch products and sugars into glucose, in humans. The target sulfonium-ion compounds were synthesized by means of nucleophilic attack of benzyl protected 1,4-anhydro-4-thio-D-arabinitol at the C-6 position of 6-O-trifluoromethanesulfonyl trisaccharides as alkylating agents. The alkylating agents were synthesized from D-glucose by glycosylation at C-4 or C-2 with maltosyl trichloroacetimidate. Deprotection of the coupled products by using a two-step sequence, followed by reduction afforded the final compounds. Evaluation of the target compounds for inhibition of the four glucosidase activities indicated that selective inhibition of one enzyme over the others is possible.     

Transport in fullerene device coupled to Cu,Ag and Au electrodes

We present an ab initio approach of the electronic transport through a single molecular junction based on C₂₀ fullerene. The electronic properties of a single molecular junction constrained within two semi-infinite metallic electrodes are largely affected by the choice of electrode material. The two-probe device formed by the mechanically control break technique has been modelled with three distinct electrode materials from group IB of the periodic table, namely copper, silver and gold. The quantum characteristics of these mechanically stable devices are obtained by utilising first-principle density functional theory together with non-equilibrium green function method. We evaluate the quantum characteristics, namely density of states, transmission spectrum, energy levels, current and conductance, which essentially determine the behaviour of a molecule linked to different electrodes. Our investigation concludes that copper, silver and gold electrode configuration in conjunction with C₂₀ fullerene behaves as metallic, non-metallic and semi-metallic in nature, respectively.     

Hydrophilic Pd-phosphines catalyzed one-pot synthesis of substituted isoquinolines,furopyridines and thienopyridines in aqueous medium

A first example of simple and efficient hydrophilic Pd-phosphine complexes catalyzed one-pot three-component reaction of ortho-bromo aldehydes, terminal alkynes and ammonium acetate proceeds through the tandem coupling-imination-annulation path for the synthesis of substituted isoquinolines, furopyridines and thienopyridines in good to excellent yields in green aqueous medium at mild temperature was described.     

Selective detection of ordered sodium signals by a jump-and-return pulse sequence

A simple pulse sequence, derived from the shaped pulse optimally exciting the central transition of a spin 3/2, can be used to selectively detect ordered sodium with a given quadrupolar coupling. The pulse sequence consists of two pulses with opposite phases and separated by a delay, called a quadrupolar jump-and-return (QJR) sequence. This QJR sequence is tested with a phantom made of sodium ions in bacteriophage and in aqueous solution and its feasibility for contrast modification based on the quadrupolar coupling is demonstrated.     

Parthenin—A Sesquiterpene Lactone with Multifaceted Biological Activities: Insights and Prospects

Parthenin, a sesquiterpene lactone of pseudoguaianolide type, is the representative secondary metabolite of the tropical weed Parthenium hysterophorus (Asteraceae). It accounts for a multitude of biological activities, including toxicity, allergenicity, allelopathy, and pharmacological aspects of the plant. Thus far, parthenin and its derivatives have been tested for chemotherapeutic abilities, medicinal properties, and herbicidal/pesticidal activities. However, due to the lack of toxicity–bioactivity relationship studies, the versatile properties of parthenin are relatively less utilised. The possibility of exploiting parthenin in different scientific fields (e.g., chemistry, medicine, and agriculture) makes it a subject of analytical discussion. The present review highlights the multifaceted uses of parthenin, on-going research, constraints in the practical applicability, and the possible workarounds for its successful utilisation. The main aim of this comprehensive discussion is to bring parthenin to the attention of researchers, pharmacologists, natural product chemists, and chemical biologists and to open the door for its multidimensional applications.     

Smallest fullerene-like clusters in two-probe device junctions: first principle study

First principle calculations based on density functional theory are realised to investigate the electron transport of the smallest fullerene-like clusters as two-probe junction devices. The junction devices are constructed by mechanically controlled break junction techniques to ensure the maximum stability of the Be₂₀, B₂₀ and N₂₀ cluster molecular junctions. We investigate the density of states, transmission spectrum, molecular orbitals, current and differential conductance characteristics at discrete bias voltages to gain insight about the various transport phenomena occurring in these nano-junctions. The results show that B₂₀ molecule when stringed to gold electrodes works as an ideal nano-device similar to the pure C₂₀ device and is more symmetric in its characteristic nature. However, in N₂₀ molecular device, the conduction is negligible due to the higher atomic interactions within N₂₀ molecule, despite the fact that it is constructed with penta-valent atoms.     

Synthesis characterization and hydroformylation activity of new mononuclear rhodium(I) compounds incorporated with polar-group functionalized phosphines

A first effort employing a range of polar-group functionalized phosphines (L ₁ –L ₇ ) to design mononuclear Rh(I) compounds of [Rh(quin-8-O)(CO)(L)] (quin-8-O = 8-hydroxy quinolate) is described. The reaction of a Rh(I) precursor [Rh(μ-Cl)(CO)₂]₂ with 8-hydroxyquinoline in the presence of a base followed by phosphines (L ₁ –L ₇ ) produced only a single isomer of [Rh(quin-8-O)(CO)(L)] compounds (1–7) with pendant, i.e. non-bonded, polar-groups (includes carboxyl, hydroxyl and formyl). A relationship between Δgd³¹P chemical shifts and the ν(C≡O) was derived to evaluate and explain the σ-donor properties of these phosphines with respect to the electronic properties of the polar groups and the extent of π-back-bonding to the CO group. These mononuclear Rh(I)-Phosphines were investigated as catalysts in the hydroformylation of 1-hexene and cyclohexene in aqueous two-phase and single-phase solvent systems. The Rh(I) catalysts with strong σ-donor and hydrophilic phosphines provided better yields and selectivities for the hydroformylation products, which is a reverse trend compared to literature reports. When the Rh(I) compounds contained strong σ-donor phosphines, the π-acceptor properties of the pyridine ring of 8-hydroxyquinolate were found to be beneficial for the facile cleavage of the CO group during hydroformylation, and additionally, to improve the kinetic stability of catalysts.