Influence of pH in La-doped SnO2 nanoparticles towards sensor applications

The present investigation has been carried out to optimize the pH level of lanthanum (La)-doped tin dioxide (SnO₂) nanoparticles towards the potential application in gas sensor. The La-doped SnO₂ nanoparticles were synthesized by sol-gel method in different pH values varying from acidic to base nature. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), ultraviolet (UV), photoluminescence (PL), and scanning electron microscopy (SEM) techniques. The XRD, UV, and PL analyses show the pH influences on the crystallite size of La-doped SnO₂ nanoparticles. The SEM images show the formation of porous structure at pH 11. Also, the electrical conductivity of 1 mol% La-doped SnO₂ at pH 3 and pH 11 were measured by impedance analyzer. In addition, we have fabricated and demonstrated device performance of synthesized La-doped SnO₂ nanoparticles for gas-sensing application. Real-time current response and long-time response to the gas sensing were also studied for the fabricated device.

     

The significance of the alkene size and the nature of the metal ion in metal-alkene complexes: a theoretical study

Cation interactions with π-systems are a problem of outstanding contemporary interest and the nature of these interactions seems to be quite different for transition and main group metal ions. In this paper, we have systematically analyzed the contrast in the bonding of Cu(+) and main group metal ions. The molecular structures and energetics of the complexes formed by various alkenes (A = C(n)H(2n), n = 2-6; C(n)H(2n- 2), n = 3-8 and C(n)H(2n + 2), n = 5-10) and metal ions (M = Li(+), Na(+), K(+), Ca(2+), Mg(2+), Cu(+) and Zn(2+)) are investigated by employing ab initio post Hartree-Fock (MP2/6-311++G**) calculations and are reported in the current study. The study, which also aims to evaluate the effect of the size of the alkyl portion attached to the π-system on the complexation energy, indicates a linear relationship between the two. The decreasing order of complexation energy with various metal ion-alkene complexes follows the order Zn(2+)-A > Mg(2+)-A > Ca(2+)-A > Cu(+)-A > Li(+)-A > Na(+)-A > K(+)-A. The increased charge transfer and the electron density at (3,-1) intermolecular bond critical point corroborates well with the size of the π-system and the complexation energy. The observed deviation from the linear dependency of the Cu(+)-A complexes is attributed to the dπ→π* back bonding interaction. An energy decomposition analysis via the reduced variational space (RVS) procedure was also carried out to analyze which component among polarization, charge transfer, coulomb and exchange repulsion contributes to the increase in the complexation energy. The RVS results suggest that the polarization component significantly contributes to the increase in the complexation energy when the alkene size increases.     

Polysorbate 80 as a Tool: Synthesis of Gold Nanoparticles

The preparation of metal nanoparticles generally requires the use of mostly toxic reducing agents according to state‐of‐the‐art procedures. Here, we report that polysorbate 80, a polymeric nonionic surfactant, when reacted with a gold salt in water at room temperature, yields well‐dispersed gold nanoparticles. Furthermore, we could control the particle size by simply altering concentration or temperature. The synthetic procedure presented here is easy, inexpensive, straightforward, and user‐friendly.

     

A plausible explanation for muon events due to radiation from Cygnus X-3

The muon events produced at Soudan-I and NUSEX proton decay detectors due to radiation from Cygnus X-3 are given a plausible explanation on the basis ofE ₆ GUT. The possibility of verifying the explanation by using the accelerator experiments is suggested.     

Trimellitate complexes of divalent transition metals with hydrazinium cation

New dihydrazinium divalent transition metal trimellitate hydrates of empirical formula (N₂H₅)₂M(Html)₂·nH₂O, where n = 1 for M = Co or Ni, and n = 2 for M = Mn, Zn, or Cd (H₃tml = trimellitic acid), and monohydrazinium cadmium trimellitate, [(N₂H₅)Cd(Html)_1.5·2H₂O] have been prepared and characterized by physico-chemical methods. Electronic spectroscopic, and magnetic moment data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of monodentate carboxylate anion (Δν = ν_asy(COO^?) ? ν_sym(COO^?) > 190 cm^?1) and coordinated N₂H₅ ⁺ ion (ν_N–N 1015 ? 990 cm^?1) in all the complexes. All the complexes undergo endothermic decomposition eliminating CO₂ in the temperature region 200–250 °C, followed by exothermic decomposition (in the range of 500–570 °C) of organic moiety to give the respective metal carbonate as the end products except nickel and cobalt complexes, which leave respective metal oxides. X-ray powder diffraction patterns reveal that Ni and Co complexes are isomorphous as are those of, Zn(II) and Cd(II) of the type, (N₂H₅)₂M(Html)₂·2H₂O.     

A Mechanochemical Approach to Nanocomposites Using Single‐Wall Carbon Nanotubes and Poly(L‐lysine)

A simple method to fabricate polymer nanocomposites with single‐walled carbon nanotubes is reported, in which the nanotubes were reacted with poly(L ‐lysine) by using high‐speed vibration milling. The nanocomposites obtained were characterized by Fourier transform infrared (FT‐IR), UV–Vis spectroscopy, and thermogravimetric methods. The morphology as well as the dispersion of the carbon nanotubes were determined by scanning and transmission electron microscopy.

     

Comparative Bioactive Studies Between Wild Plant and Callus Culture of Tephrosia tinctoria Pers.

Tephrosia tinctoria, a perennial under shrub of Fabaceae family, is endemic to Western Ghats. In this study, friable whitish yellow callus was developed after 45 days using Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid (2.0 mg/l)?+?6-benzylaminopurine (0.5 mg/l) in various explants of T. tinctoria. The ethyl acetate extracts of leaf (LE), stem (SE), and root (RE) were compared with leaf (LCE), stem (SCE), and root (RCE) derived callus, for antioxidant and antiproliferative activities. The SE possessed the highest phenolic and flavonoid content among all the extracts tested and showed a significant antioxidant assays. The study of anticancer activity on human hepatocellular carcinoma (HepG2) cell line revealed that the callus extracts especially RCE possessed significant inhibition of cell growth (IC₅₀ 20 μg/ml) at 72 h treatment period on analysis with MTT assay. The apoptotic cell death was observed through DNA fragmentation analysis in HepG2 cells treated with the T. tinctoria extracts. The gas chromatography–mass spectrometry finger printing profile showed that more than 60 % percentage of metabolites are similar in both SE and SCE. The higher percentage area of antioxidant compound (stigmast-4-en-3-one) was observed in SE (2.01 %) and higher percentage area of anticancer compound (phenol, 2,4-bis(1,1-dimethylethyl)) in SCE (0.91 %). In addition to that, callus extracts contain squalene, which is used for target deliver and also used as anticancer drug. Thus, the present study revealed that the T. tinctoria has potent antioxidant and antiproliferative activity and the callus culture can be used for the production of the bioactive compounds due to the endemic nature of this plant.     

Synthesis of novel 1-benzyl/aryl-4-{[(1-aryl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-4-yl)methoxy]methyl}-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole derivatives and evaluation of their antimicrobial activity

A series of 1-benzyl/aryl-4-{[(1-aryl-1H-1,2,3-triazol-4-yl)methoxy]methyl}-1H-1,2,3-triazole derivatives were synthesized via Cu(I) catalyzed reaction between terminal alkyne and substituted aryl or benzyl azides. The synthesized triazoles were characterized by 1H NMR, 13C NMR, IR, and mass spectral techniques. All the synthesized compounds were screened for their antimicrobial activity.