On certain Ramanujan's mock theta functions

Ramanujan's last gift to the mathematicians was his ingeneous discovery of the mock theta functions of order three, five and seven. Recently, Andrews and Hickerson found a set of seven more functions in Ramanujan's Lost Note Book and formally labelled them as mock theta functions of order six. In this paper the complete forms of these functions have been studied and connected with the bilateral basic hypergeometric series₂Ψ₂. Several other interesting properties and transformations have also been studied.     

Systematic trends in the line strengths of E1 transitions in the oxygen isoelectronic sequence

Line strengthsS for the dipole allowed transitions within then=2 complex of the oxygen isoelectronic sequence have been fitted in the formZ ² S=A+B/(Z −C), whereZ is the nuclear charge of a particular ion. The constantsA, B andC are determined by using a non-linear least square method. The data forS are taken from the configuration interaction calculations which included internal, semi-internal and all external type correlations for ions in the rangeZ=8 − 25. It is shown that the values ofA obtained from the fit for all the transitions are in excellent accord with the ab-initio values obtained in the hydrogenic limitZ → ∞ provided near degeneracy effects are included in the ground state multiplet 1s²2s²2p^{4 1}S.     

Potential Application of Alkaline Pectinase from <Emphasis Type="Italic">Bacillus subtilis</Emphasis> SS in Pulp and Paper Industry

Pectinase production from Bacillus subtilis SS was optimized under solid-state fermentation (5,943 U/g of dry bacterial bran). The pectinase produced was stable in neutral to alkaline pH range at 70 degrees C; therefore, the suitability of this pectinase in pulp and paper industry was investigated. The enzyme pretreatment process was optimized, and a pectinase dose of 5 IU/g of oven-dried pulp (10% consistency) at pH 9.5 temperature 70 degrees C after 150 min of treatment gave the best pretreatment to the pulp. An increase of 4.3% in brightness along with an increase of 14.8 and 65.3% in whiteness and fluorescence, respectively, whereas a 15% decrease in the yellowness of the pretreated pulp were observed. There was a 5.85% reduction in kappa number and 6.1% reduction in permanganate number along with a reduction in the chemical oxygen demand value. Significant characteristics showed by pectinase open new possibilities of application of this cellulase-free enzyme in the pulp and paper industry by reducing the negative environmental impact of chemicals apart from improving the properties of paper.     

Guanine-Stabilized Formamidinium Lead Iodide Perovskites

Formamidinium (FA) lead iodide perovskite materials feature promising photovoltaic performances and superior thermal stabilities. However, conversion of the perovskite α-FAPbI₃ phase to the thermodynamically stable yet photovoltaically inactive δ-FAPbI₃ phase compromises the photovoltaic performance. A strategy is presented to address this challenge by using low-dimensional hybrid perovskite materials comprising guaninium (G) organic spacer layers that act as stabilizers of the three-dimensional α-FAPbI₃ phase. The underlying mode of interaction at the atomic level is unraveled by means of solid-state nuclear magnetic resonance spectroscopy, X-ray crystallography, transmission electron microscopy, molecular dynamics simulations, and DFT calculations. Low-dimensional-phase-containing hybrid FAPbI₃ perovskite solar cells are obtained with improved performance and enhanced long-term stability.     

Identification of the antioxidant principles of Polyalthia longifolia var. pendula using TEAC assay

Activity-guided fractionation of the ethanolic extract of the leaves of the Polyalthia longifolia var. pendula led to the identification of quercetin (1), quercetin-3-O-β-glucopyranoside (2), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-β-galactopyranoside (3), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-β-glucopyranoside (4), rutin (5) and allantoin (6) as the active constituents from the butanol fraction. Compounds 2-4 are reported for the first time from this natural source. Structures of the compounds were confirmed on the basis of their 1D and 2D NMR coupled with other spectroscopic methods. All the isolated compounds and the fractions were evaluated for their antioxidant potential using the TEAC assays and it was found that the activity of the active fraction was due to quercetin (1) and its glycosides (2 and 5), with TEAC values of 4.10, 1.91 and 2.38 mM, respectively, while the kaempferol glycosides were found to be inactive. This is the first study on the antioxidant activity of this plant species.     

Effects of laponite and silica nanoparticles on the cleaning performance of amylase towards starch soils

This work aims to understand the effect of nanoparticle-enzyme interactions and how such interactions affect starch based soil removal. Silica and laponite are used as the model nanoparticles, and s-amylase is employed as the model enzyme. The results show that, if the nanoparticles and enzyme are added simultaneously, laponite enhances the enzyme performance toward starch soil removal, whereas silica imposes a small effect on the enzymatic activity towards the same soil substrates. However, when nanoparticles are added first, the enzyme activity is not affected much by laponite but is hindered significantly by silica nanoparticles. Furthermore, sequential addition of the enzyme followed by silica nanoparticles improves soil removal. Electron microscopic analyses, measurements of the enzyme activity in suspen- sions of nanoparticles, and particle size characterisation suggest that dense coverage of soil surface by the silica nanoparticles be likely a mechanism for the experimentally observed hindrance of soil removal when silica nanoparticles are added before enzyme.     

Magneto-optic phase shift in plasmon propagation along garnet/semiconductor-on-insulator structures

This paper discusses the magneto-optic phase shift in garnet/semiconductor-on-insulator plasmonic waveguides. We consider two structures: (1) Y IG/Si/SiO₂ and (2) Y IG/GaInAsP/AlInAs-oxide. A dispersion relation for the plasmon propagation has been derived and the nonreciprocal phase shift of the fundamental TM mode has been determined at wavelengths of 1.55 μm, 1.5 μm and 1.3 μm.     

迈克耳逊干涉仪测激光波长的系统误差

本文探讨了迈克耳逊干涉仪测激光波长的系统误差的产生原因并提出了减小这一误差的方法。     

Enantioselective total syntheses of (−)-clavaminol A and deacetyl (+)-clavaminol H

An efficient enantioselective approach to the syntheses of (?)-clavaminol A and deacetyl (+)-clavaminol H is presented, starting from n-decanol. The synthesis features Sharpless asymmetric dihydroxylation (AD), regioselective epoxide formation/opening and α-tosylation as key steps.     

Folic Acid as a Bimodal Optical Probe for the Detection of TNT

Rapid and onsite detection of nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) is very crucial for the safety and security of human life as well as for the environment. In this present work, we demonstrate the feasibility for employing Folic Acid (FA) as a fluorescent as well as a colorimetric probe for the detection of TNT. This probe was synthesized by a simple one-step process. The developed probe shows an emission maximum at 490 nm upon excitation at 420 nm. On adding TNT, the fluorescence of the FA probe is quenched. Also, it shows a good selectivity towards TNT over other similar organic compounds such as 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP) and picric acid (PA). The limit of detection (LoD) of TNT was found to be 1.9398 µM. Colorimetric detection was conducted and paper strip assay was developed for the practical applications.

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