Determination of oxygen in zirconium by the platinum flux technique

The platinum flux technique, well established for the determination of oxygen in titanium, was successfully applied to the analysis of zirconium for its oxygen content after a systematic study of the optimum experimental conditions. The extraction of oxygen was complete in 20 min in the temperature range of 1850 to 2100° with a ratio of flux to sample of about 4.5:1 to 8:1. Statistical analysis of the results on a homogeneous sample gave a standard deviation of 0.0038 weight % and a coefficient of variance of 2.9%atalevelof 0.131 weight % of oxygen in zirconium. The recommended experimental conditions are a 0.1-g sample, a 5:1 flux-to-sample ratio, and 20 min extraction at 1900°–1950°.     

Vibrational spectra and rotational isomerism of allyl amine

The infrared spectra of allyl amine in the vapour, liquid and solid phases have been measured from 250 to 4000 cm⁻¹. The laser-Raman spectrum in the liquid state has also been recorded photoelectrically and qualitative depolarization measurements have been made. The interpretation of the spectral data suggests the presence of two rotational isomers (‘cis and trans”, and ‘ganche and trans’) in the vapour and liquid phases whereas the form having asymmetrical structure (‘gauche and trans’, C₁ symmetry) gets stabilized in the solid state at low temperature.     

The emission spectrum of iodine bromide excited in the presence of Argon

IBr vapour was excited in the presence of argon by an uncondensed transformer discharge. Four band systems were obtained in the regions 5425–5360 Å, 4520–4415 Å, 4120–4010 Å and 3915–3540 Å of which the first three are discussed in this paper. The wavelengths and wavenumbers of the band heads in three systems as measured from the plates obtained with a 3-prism Steinheil glass spectrograph are given along with their visually estimated relative intensities. The three band systems, which are new, are analysed and the following vibrational constants expressed in cm.^?1 are obtained:

Band system	v e	w e ″	w e ″x e ″	w e ″y e ″	w e ′	w e ′x e ′
5425-5360 Å	18613	65·5	0·24	?0·01	43·0	0·026
4520-4415 Å	22312	65·5	0·24	?0·01	77·0	0·5
4120-4010 Å	24540	160·6	1·125	..	128·4	0·1

     

Creeping flow of an ellis fluid past a Newtonian fluid sphere

Upper and lower bounds on the drag offered to a Newtonian fluid sphere placed in an Ellis model fluid in creeping flow have been found using variational principles. For a solid sphere, the bounds are in good agreement with those reported by earlier investigators.     

Creeping flow of a power law fluid past a fluid sphere

The stress variational principle is employed to obtain the lower bound for the drag offered by the creeping flow of a power law fluid past a Newtonian fluid sphere. In spite of the unprescribed interfacial velocity, a bound-on-bound approach yields bounds that are close to the upper bound obtained by Mohan (1974). Furthermore, for very viscous drops (solid behavior) the theory gives lower bounds that differ considerably from those of Wasserman & Slattery (1964) and show good agreement with the results of Yoshioka & Adachi (1973). The approach presented in this work provides an insight into the method of analyzing multiphase flow situations involving non-Newtonian fluids.     

Fused Quinazolinoquinazolinones: Synthesis,Isomerization, Spectroscopic Identification,and Anticancer Activity

13H‐quinazolino[3,4‐a]quinazolin‐13‐ones have been synthesized from 2‐aminobenzamides in four steps. An acid‐catalyzed or base‐catalyzed isomerization of 13H‐quinazolino[3,4‐a]quinazolin‐13‐ones to 8H‐quinazolino[4,3‐b]quinazolin‐8‐ones in excellent yields (90–95%) has been reported. The differences in the infrared and nuclear magnetic resonance (¹H & ¹³C) data of these isomeric fused quinazolinoquinazolinones afford a useful method for distinguishing between the two series. These analogs showed moderate anticancer activity (EGFR‐TK inhibition).     

On the direct construction of recursive MDS matrices

MDS matrices allow to build optimal linear diffusion layers in the design of block ciphers and hash functions. There has been a lot of study in designing efficient MDS matrices suitable for software and/or hardware implementations. In particular recursive MDS matrices are considered for resource constrained environments. Such matrices can be expressed as a power of simple companion matrices, i.e., an MDS matrix \(M = C_g^k\) for some companion matrix corresponding to a monic polynomial \(g(X) \in \mathbb {F}_q[X]\) of degree k. In this paper, we first show that for a monic polynomial g(X) of degree \(k\ge 2\), the matrix \(M = C_g^k\) is MDS if and only if g(X) has no nonzero multiple of degree \(\le 2k-1\) and weight \(\le k\). This characterization answers the issues raised by Augot et al. in FSE-2014 paper to some extent. We then revisit the algorithm given by Augot et al. to find all recursive MDS matrices that can be obtained from a class of BCH codes (which are also MDS) and propose an improved algorithm. We identify exactly what candidates in this class of BCH codes yield recursive MDS matrices. So the computation can be confined to only those potential candidate polynomials, and thus greatly reducing the complexity. As a consequence we are able to provide formulae for the number of such recursive MDS matrices, whereas in FSE-2014 paper, the same numbers are provided by exhaustively searching for some small parameter choices. We also present a few ideas making the search faster for finding efficient recursive MDS matrices in this class. Using our approach, it is possible to exhaustively search this class for larger parameter choices which was not possible earlier. We also present our search results for the case \(k=8\) and \(q=2^{16}\).     

Efficient PEG-mediated green synthesis of isoaurones: First synthesis of 4′,6-dihydroxy-4-methoxyisoaurone isolated from Trichosanthes kirilowii

An efficient and green protocol for the synthesis of isoaurones by condensation of benzofuranone with benzaldehydes using polyethylene glycol (PEG) is demonstrated. Excellent yields, no reagents/additional catalysts, E-selectivity, short reaction times, and no work-up/extraction makes an attractive benign procedure. Additionally, 4′,6-dihydroxy-4-methoxyisoaurone isolated from Trichosanthes kirilowii has been synthesized for the first time and confirmed its geometry as E.     

Synthesis, structural revision, and biological activities of 4′-chloroaurone, a metabolite of marine brown alga Spatoglossum variabile

4′-Chloroaurone (1a), the only aurone reported from a marine source, Spatoglossum variabile was synthesized from 2-hydroxyacetophenone along with six structural analogs. The products obtained were Z-isomers and these were converted into E-isomers by photoisomerization. The E and Z isomers of aurones showed distinct proton and carbon chemical shifts. However, the spectroscopic data of either Z-4′-chloroaurone (1a) or its E-isomer (2a) did not match with those reported for the natural product and thus requires revision of the structure assigned. The proton NMR spectroscopic data reported for the natural product matches with those reported for a known isocoumarin (5). The synthesized E and Z aurones were evaluated for their antioxidant and antibacterial activities. The aurone, Z-2-[(3,4-dihydroxyphenyl)methylene]benzo[b]furan-3-one exhibited significant antioxidant activity. Interestingly, Z-aurones are active against Gram-positive and Gram-negative bacteria, whereas the corresponding E-aurones were inactive.