Ultrasonic velocity and allied acoustical parameters of 2, 4-dinitrophenyl hydrazine based Schiff base in DMSO

1108-1112Novel 2, 4-dinitrophenyl hydrazine based Schiff bases (L1-L3) has been successfully synthesized and characterized. The ultrasonic velocity (C) and density (ρ) has been measured for the synthesized Schiff bases with DMSO (Dimethyl sulfoxide) solvents at 300 K. Using these experimental data ultrasonic Velocity, adiabatic compressibility, intermolecular free length and specific acoustic impedance have been evaluated. From the experimental data, it has been found that L1 ascribed higher ultrasonic velocity as compared to other molecular probes L2 and L3. The strength and nature of interaction between the molecular probes and DMSO solvents has been discussed. Scanning electron microscope studies of molecular probes are performed to discuss the microstructure and surface functionalities

Selective detection of fluoride and hydrogen sulfate anions by pyrimidine-based fluorescence chemosensor

1809-1813The binding and sensing abilities of pyrimidine based fluorescence chemosensor L towards different anions such as F-, Cl-, Br-, I-, NO3-, ClO4-, H2PO4- and HSO4- have been examined by fluorescence spectroscopy in DMSO-H2O (7: 3, v/v). Upon successive addition of various anions to DMSO-H2O solutions of L; quenching in emission fluorescence is observed at 480 nm. Analysis of fluorescence emission changes suggested the formation of 1:1 complex of L with the anions. From the fluorescence binding constant data, it is found that L form strong complexes with F- and HSO4- ions through H-bonding interactions. The selective response of F- over other halides and HSO4- amongst other oxo-anions towards L may be explained on the basis of photo-induced electron transfer process

The COVID-19 Pandemic Affects Seasonality, With Increasing Cases of New-Onset Type 1 Diabetes in Children, From the Worldwide SWEET Registry

Objective: To analyze whether the coronavirus disease 2019 (COVID-19) pandemic increased the number of cases or impacted seasonality of new-onset type 1 diabetes (T1D) in large pediatric diabetes centers globally. Research design and methods: We analyzed data on 17,280 cases of T1D diagnosed during 2018-2021 from 92 worldwide centers participating in the SWEET registry using hierarchic linear regression models. Results: The average number of new-onset T1D cases per center adjusted for the total number of patients treated at the center per year and stratified by age-groups increased from 11.2 (95% CI 10.1-12.2) in 2018 to 21.7 (20.6-22.8) in 2021 for the youngest age-group, <6 years; from 13.1 (12.2-14.0) in 2018 to 26.7 (25.7-27.7) in 2021 for children ages 6 to <12 years; and from 12.2 (11.5-12.9) to 24.7 (24.0-25.5) for adolescents ages 12-18 years (all P < 0.001). These increases remained within the expected increase with the 95% CI of the regression line. However, in Europe and North America following the lockdown early in 2020, the typical seasonality of more cases during winter season was delayed, with a peak during the summer and autumn months. While the seasonal pattern in Europe returned to prepandemic times in 2021, this was not the case in North America. Compared with 2018-2019 (HbA1c 7.7%), higher average HbA1c levels (2020, 8.1%; 2021, 8.6%; P < 0.001) were present within the first year of T1D during the pandemic. Conclusions: The slope of the rise in pediatric new-onset T1D in SWEET centers remained unchanged during the COVID-19 pandemic, but a change in the seasonality at onset became apparent.info:eu-repo/semantics/publishedVersio

Investigation on bindings of a binaphthoquinone derivative with serum albumin proteins by fluorescence spectroscopy

824-829Binding of a binaphthoquinone derivative namely, 5a,5b-dimethyldibenzo[b,h]biphenylene-5,6,11,12(5aH,5bH,11aH,11bH)-tetraone (L, C22H16O4) with bovine serum albumin (BSA) and human serum albumin (HSA) have been examined by using fluorescence spectroscopy. The fluorescence emission of the L is quenched upon addition of L to a solution of BSA or that of HSA, but the BSA has shown a higher affinity towards L over the HSA protein. A molecular docking study is also performed to suggest the sites of BSA for weak interactions to bind the L. The docking analysis, has revealed the N-H•••O hydrogen bonds of L with different amino acid residues. The L is located at about 7.7Å away from the Trp-213 which is the fluorescent unit of the BSA suggesting the role of environment of the tryptophan residue to be an important to have changed the emission intensities

Polymorphs and Solvates of 2-(1,4-Dihydro-1,4-dioxonaphthalen-3-ylthio)benzoic Acid

Three conformational polymorphs of 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio) benzoic acid (<b>L</b>), an acetonitrile solvate of <b>L</b>, and cocrystal of <b>L</b> with 2,2′-bipyridine are structurally characterized. The two polymorphs <b>I</b> and <b>II</b> have <i>Z</i>′ = 1 and possess R₂²(8) type of dimeric structure in which the two aromatic rings are in trans disposition across the cyclic hydrogen bonded motifs. However, the dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone rings are −129.38° and 126.56°, respectively. The polymorph <b>III</b> has <i>Z</i>′ = 2; it shows R₂²(8) type of dimeric structures which are formed by two symmetry independent molecules. In its crystal lattice, the aromatic rings across the cyclic hydrogen bond motifs are in cis dispositions. Dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone ring in the two symmetry independent molecules are 114.82° and 125.27°, respectively. The acetonitrile solvate of <b>1</b> has <i>Z</i>′ = 3. In its crystal lattice, it has two symmetry independent molecules forming R₂²(8) hydrogen bonds to form dimeric assemblies and another cyclic R₂²(8) type hydrogen bond geometry between molecules which constitute the third set of symmetry independent molecules. The 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio)­benzoic acid also forms a 2:1 cocrystal with 2,2′-bipyridine; in this cocrystal the two nitrogen atoms are trans to each other and they participate in hydrogen bonds with carboxylic acids

Polymorphs and Solvates of 2-(1,4-Dihydro-1,4-dioxonaphthalen-3-ylthio)benzoic Acid

Three conformational polymorphs of 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio) benzoic acid (<b>L</b>), an acetonitrile solvate of <b>L</b>, and cocrystal of <b>L</b> with 2,2′-bipyridine are structurally characterized. The two polymorphs <b>I</b> and <b>II</b> have <i>Z</i>′ = 1 and possess R₂²(8) type of dimeric structure in which the two aromatic rings are in trans disposition across the cyclic hydrogen bonded motifs. However, the dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone rings are −129.38° and 126.56°, respectively. The polymorph <b>III</b> has <i>Z</i>′ = 2; it shows R₂²(8) type of dimeric structures which are formed by two symmetry independent molecules. In its crystal lattice, the aromatic rings across the cyclic hydrogen bond motifs are in cis dispositions. Dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone ring in the two symmetry independent molecules are 114.82° and 125.27°, respectively. The acetonitrile solvate of <b>1</b> has <i>Z</i>′ = 3. In its crystal lattice, it has two symmetry independent molecules forming R₂²(8) hydrogen bonds to form dimeric assemblies and another cyclic R₂²(8) type hydrogen bond geometry between molecules which constitute the third set of symmetry independent molecules. The 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio)­benzoic acid also forms a 2:1 cocrystal with 2,2′-bipyridine; in this cocrystal the two nitrogen atoms are trans to each other and they participate in hydrogen bonds with carboxylic acids

Polymorphs and Solvates of 2-(1,4-Dihydro-1,4-dioxonaphthalen-3-ylthio)benzoic Acid

Three conformational polymorphs of 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio) benzoic acid (<b>L</b>), an acetonitrile solvate of <b>L</b>, and cocrystal of <b>L</b> with 2,2′-bipyridine are structurally characterized. The two polymorphs <b>I</b> and <b>II</b> have <i>Z</i>′ = 1 and possess R₂²(8) type of dimeric structure in which the two aromatic rings are in trans disposition across the cyclic hydrogen bonded motifs. However, the dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone rings are −129.38° and 126.56°, respectively. The polymorph <b>III</b> has <i>Z</i>′ = 2; it shows R₂²(8) type of dimeric structures which are formed by two symmetry independent molecules. In its crystal lattice, the aromatic rings across the cyclic hydrogen bond motifs are in cis dispositions. Dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone ring in the two symmetry independent molecules are 114.82° and 125.27°, respectively. The acetonitrile solvate of <b>1</b> has <i>Z</i>′ = 3. In its crystal lattice, it has two symmetry independent molecules forming R₂²(8) hydrogen bonds to form dimeric assemblies and another cyclic R₂²(8) type hydrogen bond geometry between molecules which constitute the third set of symmetry independent molecules. The 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio)­benzoic acid also forms a 2:1 cocrystal with 2,2′-bipyridine; in this cocrystal the two nitrogen atoms are trans to each other and they participate in hydrogen bonds with carboxylic acids

57Fe internal field nuclear magnetic resonance and Mössbauer spectroscopy study of Li-Zn ferrites

We report the internal field nuclear magnetic resonance (IFNMR) and Mössbauer spectroscopy study of Li-Zn ferrites at RT. The results were supported by the IFNMR data measured at 77 K. As Zn concentration increases the IFNMR echo amplitude decreases and below certain Zn concentration no signal was detected. At RT the echo amplitude vanishes at a lower Zn concentration, whereas at 77 K, the echo amplitude does not vanish completely (except for pure Zn-ferrite). However, in Mössbauer spectroscopy at RT, we have observed magnetically ordered state of all the Li-Zn ferrite samples. This discrepancy could be related to the difference between the time scale of detection of the spins by Mössbauer spectroscopy (10−7–10−10 s) and NMR spectroscopy (10−6 s). Hence, sensitivity of zero-field NMR depends on the magnetic hyperfine field, temperature and abundance of the magnetic cations at the lattice of the spinel ferrites. We have demonstrated that the ‘two-equal-pulses’ sequence leads to higher echo signal than the spin echo pulse sequence due to the presence of distribution of internal magnetic fields throughout the material. We obtained a limiting value for the fraction of spins needed to produce an echo signal at a particular temperature and at a particular site of the Li-Zn ferrite spinels that can be sensitively detected by pulsed IFNMR technique. © 2017 Elsevier Inc

Annealing temperature dependent structural and magnetic properties of MnFe2O4 nanoparticles grown by sol-gel auto-combustion method

Manganese ferrite (MnFe2O4) nanoparticles were synthesized by sol-gel auto-combustion method using manganese nitrate and ferric nitrate as precursors and citric acid as a fuel. Scanning electron micrographs show irregularly shaped morphology of the particles. The as-prepared samples were annealed at 400, 500, 600 and 800 degrees C for 2 h in air. The phase identification and structural characterizations were performed using powder X-ray diffraction technique along with Mossbauer spectroscopy. Magnetization loops and Fe-57 Mossbauer spectra were measured at RT. After annealing the sample at or below similar to 500 degrees C, we observed two different spinel phases corresponding to two different lattice parameters. This is originating due to the partial oxidation of Mn2+ to Mn3+. At high annealing temperatures (similar to 600 degrees C or above) the spinel MnFe2O4 phase decomposes into crystalline alpha-Mn2O3 and alpha-Fe2O3 phases, and amorphous FeO phase. (c) 2017 Elsevier B.V. All rights reserved