Hyperfine suppression of 2 3 S 1--3 3 P J transitions in 3He

Two anomalously weak transitions within the 2(3)S_(1)--3(3)P_(J) manifolds in 3He have been identified. Their transition strengths are measured to be 1000 times weaker than that of the strongest transition in the same group. This dramatic suppression of transition strengths is due to the dominance of the hyperfine interaction over the fine-structure interaction. An alternative selection rule based on IS coupling (where the nuclear spin is first coupled to the total electron spin) is proposed. This provides qualitative understanding of the transition strengths. It is shown that the small deviations from the IS coupling model are fully accounted for by an exact diagonalization of the strongly interacting states.     

Kinetic investigation on the curing of ethylene methyl acrylate—Polydimethyl siloxane rubber blends by differential scanning calorimetry

Curing reactions of ethylene methyl acrylate (EMA) polydimethyl siloxane (PDMS) rubber blends have been investigated by differential scanning calorimetry (DSC) and by Rheometry. The curing exoterms obtained from DSC curves have been analysed to derive the kinetic parameters associated with the curing process. Crosslinking of EMA-PDMS rubber blends follow first order kinetics. The effect of blend ratio and peroxide concentration on the crosslinking characteristics of the blends have also been investigated. Department of Metallurgical Engineering     

Diversified Synthesis of Furans by Coupling between Enols/1,3‐Dicarbonyl Compounds and Nitroolefins: Direct Access to Dioxa[5]helicenes

A versatile method for the diversified synthesis of furans and arenofurans has been developed that proceeds through K₂CO₃‐promoted cyclization between enols/1,3‐dicarbonyl compounds and nitroolefins at reflux in EtOH. This facile method has been successfully employed in the synthesis of benzotrifuran derivatives, which are useful hole‐transporting materials. This procedure also provides direct access to dioxa[5]helicenes. This reaction offers a broad substrate scope, uses an inexpensive base and environmentally benign solvent, and is operationally simple.     

Pure and Hybrid SCAN,rSCAN, and r2SCAN: Which One Is Preferred in KS- and HF-DFT Calculations,and How Does D4 Dispersion Correction Affect This Ranking?

Using the large and chemically diverse GMTKN55 dataset, we have tested the performance of pure and hybrid KS-DFT and HF-DFT functionals constructed from three variants of the SCAN meta-GGA exchange-correlation functional: original SCAN, rSCAN, and r²SCAN. Without any dispersion correction involved, HF-SCANn outperforms the two other HF-DFT functionals. In contrast, among the self-consistent variants, SCANn and r²SCANn offer essentially the same performance at lower percentages of HF-exchange, while at higher percentages, SCANn marginally outperforms r²SCANn and rSCANn. However, with D4 dispersion correction included, all three HF-DFT-D4 variants perform similarly, and among the self-consistent counterparts, r²SCANn-D4 outperforms the other two variants across the board. In view of the much milder grid dependence of r²SCAN vs. SCAN, r²SCAN is to be preferred across the board, also in HF-DFT and hybrid KS-DFT contexts.     

Synthesis of Near-Infrared-Emitting Benzorhodamines and Their Applications to Bioimaging and Photothermal Therapy

Photostable and near-infrared (NIR)-emitting organic fluorophores with large Stokes shifts are in great demand for long-term bioimaging at deeper depths with minimal autofluorescence and self-quenching. Herein, a new class of benzorhodamines and their analogues that are photostable and emit in the NIR region (up to 785 nm) with large Stokes shifts (>120 nm) is reported. The synthesis involves condensation of 7-alkylamino-2-naphthols with 2-[4-(dimethylamino)-2-hydroxybenzoyl]benzoic acid, which leads to bent-shaped benzorhodamines that emit orange fluorescence (≈600 nm); however, introduction of steric hindrance near the condensation site switched the regioselectivity, to provide a linear benzorhodamine system for the first time. The linear benzorhodamine derivatives provide bright fluorescence images in cells and in tissue. A carboxy-benzorhodamine was applied for photothermal therapy of cancer cells and xenograft cancer mice.     

Syntheses,characterizations, crystal structures,DFT/TD-DFT,luminescence behaviors and cytotoxic effect of bicompartmental Zn (II)-dicyanamide Schiff base coordination polymers: An approach to apoptosis,autophagy and necrosis type classical cell death

Two new Zn (II)-dicyanamide (dca) 1-D chain coordination polymers (CPs), [Zn (L^OMe)(μ₁-dca)(μ_1,5-dca)]_n (1) and [Zn (L^OEt)(μ₁-dca)(μ_1,5-dca)]_n (2) have been successfully synthesized from bicompartmental Schiff base ligands N,N^′-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane (H₂L^OMe), N,N^′-Bis(3-ethoxysalicylidenimino)-1,3-diaminoproane (H₂L^OEt) respectively and structurally characterized using various spectroscopic protocols like ¹H NMR, IR, Raman, UV–Vis, fluorescence as well as elemental analysis, TGA, PXRD and SCXRD studies. X-ray single crystal study revealed that both the complexes have two different geometrical arrangement of Zn metal centres with distorted square pyramidal Zn(2) and trigonal prismatic geometry Zn(1). Ab-initio DFT (Density functional theory) has been executed at B3LYP (Becke, 3-parameter, Lee-Yang-Parr) using DGDVP (Diffuse gradient double valence polarised) basis set to explain FMO (Frontier molecular orbital), TD-DFT (Time-dependent density functional theory) and photovoltaic efficiency in Dye Sensitized Solar Cell (DSSC). Hirshfeld surface (HS) and 2D fingerprint plot analyses are shed more light on the non-covalent supramolecular interactions. The steady state and time-resolved fluorescence measurements have been conducted in DMSO and solid-state. CPs exhibited bi-exponential decay in DMSO as well as solid-state where fluorescence behaviors are mainly intra-ligand (π → π^*) in nature with lifetimes in the range (1.11–1.06 ns). In particular, in vitro cytotoxic activities were evaluated towards MCF7 (breast cancer) cell line, MDA-MB-231 (breast carcinoma) cell line and MCF10A (breast epithelial) cell line using MTT assay. CP 1 had lower cytotoxic effect against MCF7 (20 μM), MDA-MB-231 (15 μM) cell lines in comparison with cisplatin (42.2 ± 8, 128.2 ± 7 μM). CP 1 induced classical cell death apoptosis, autophagy and necrosis. Lower IC₅₀ value of CP 1 against MDA-MB-231 cell line provide new insights in the development of cancer therapeutics.     

Application of particle induced gamma-ray emission for non-destructive determination of fluorine in barium borosilicate glass samples

Barium borosilicate glass (BaBSG) is proposed as a potential candidate for vitrification of nuclear waste generated from thoria based nuclear reactors. Along with fission products, activation products and many inactive chemicals, like fluorine in the form of HF are expected to be present in the dissolver solution with nuclear waste. As vitrification occurs at high temperature, it is important to quantify fluorine in BaBSG. Due to its complex matrix, most of the wet chemical and nuclear analytical methods encounter problems in the estimation of fluorine. Particle induced γ-ray emission (PIGE) method has been standardized for non-destructive determination of fluorine contents in BaBSG samples utilizing measurement of prompt gamma-rays from ¹⁹F (p, p’γ) ¹⁹F reaction. Experiments have been carried out with thick pellet targets prepared in cellulose matrix using 4 MeV proton beam from the folded tandem ion accelerator at BARC, Mumbai. For obtaining current normalized count rate of interest, beam current variation was monitored by the Rutherford backscattering spectrometry (RBS) method as well as by the in situ approach using an externally added element sensitive to PIGE. In this paper standardization of PIGE methods for F determination, validation of methods using synthetic samples, and application to BaBSG samples are reported.     

A "reactive" ratiometric fluorescent probe for mercury species

A ratiometric fluorescent probe for mercury species is developed based on the metal-promoted hydrolysis of a vinyl ether derivative of 2-(benzothiazol-2-yl)phenol in a buffer solution. The probe responds selectively to mercury species over various other metal ions with a marked fluorescence change from blue to cyan through the excited state intramolecular proton transfer (ESIPT) process. The fluorescence titration is complete with 0.5 equiv of HgCl(2), which indicates that the probe also responds to organomercury species, RHgCl.