Thermal and electrical studies on composite gel electrolyte system: PEG–PVA–(NH4CH2CO2)2

The present article reports the synthesis and characterisation of a highly conducting composite polymer gel electrolyte, namely polyethylene glycol–polyvinyl alcohol (PVA)–ammonium succinate system. Formation of an amorphous composite gel electrolyte has been evidenced in differential scanning calorimetry experiments. Thermogravimetric analysis of the composite gel electrolyte has shown better thermal stability of films containing 25 wt% PVA. Composite gel system containing 10 wt% PVA exhibits optimal ionic conductivity (4.0 × 10^?4 s cm^?1) and its variation with temperature follows Vogel, Tamman and Fulcher relationship. The magnitude of variation in ionic conductivity (with temperature) of these composite electrolytes and its Williams, Landel and Ferry fit reveals liquid-like charge transport. Composite electrolyte with 25 wt% PVA appears to be a suitable candidate for device applications on the basis of experimental findings.     

Influence of the addition of aluminium nanoparticles on thermo-rheological properties of hydroxyl-terminated polybutadiene-based composite propellant and empirical modelling

The heat transfer performance and entropy analysis are done in a compact loop heat pipe (CLHP) with Al₂O₃/water and Ag/water nanofluid. A compact loop heat pipe having a flat square evaporator with dimensions of 34 mm (L)?×?34 mm (W)?×?19 mm (H) has been fabricated and tested for the heat load ranging from 30 to 500 W. The experimental tests are conducted by keeping the CLHP in the vertical orientation with distilled water, silver (Ag)/water and aluminium oxide (Al₂O₃)/water nanofluid having low volume concentrations of (0.09% and 0.12%). The effect of wall and vapour temperature, evaporator and condenser heat transfer coefficient, thermal resistance on the applied heat loads is experimentally investigated and compared. The experimental results showed that the evaporator thermal resistance is reduced by 34.70% and 20.21%, respectively, for 0.12 vol% of Ag, Al₂O₃ nanoparticles when compared with that of the distilled water. For the same volume concentrations of Ag, Al₂O₃ nanoparticles, an enhancement of 34.52%, 23.7%, 39.27% and 30.8%, respectively, observed for the convective heat transfer coefficients at the evaporator and condenser. The entropy is also reduced by 19.08% and 11.58% when Ag and Al₂O₃ nanofluids are used as the operating fluid. From the experimental tests, it is found that the addition of small amount of Ag nanoparticles in the working fluid enhanced the operating range by 15% when compared with that of Al₂O₃/water nanofluid without the occurrence of any dry-out conditions.

     

Isolation and antiproliferative activity of triterpenoids and fatty acids from the leaves and stem of Turraea vogelii Hook. f. ex benth

Chloroform extract from the leaves of Turraea vogelii Hook f. ex Benth demonstrated cytotoxic activity against a chronic myelogenous leukemia cell, K-562 with IC₅₀ of 14.27 μg/mL, while chloroform, ethyl acetate and methanol extracts from the stem of the plant inhibited K-562 cells growth with IC₅₀ of 19.50, 24.10 and 85.40 μg/mL respectively. Bioactive chloroform extract of Turraea vogelii leaves affords two triterpenoids: oleana-12,15,20-trien-3β-ol (1), and oleana-11,13-dien-3β,16α,28-triol (2), with six fatty esters, ethyl hexaeicos-5-enoate (3), 3-hydroxy-1,2,3-propanetriyltris(tetadecanoate) (4), 1,2,3-propanetriyl(7Z,7′Z,7′′Z)tris(-7-hexadecenoate) (5), 1,2,3-propanetriyl(5Z,5′Z,5′′Z)tris(-5-hexadecenoate) (6), 1,2,3-propanetriyltris(octadecanoate) (7), and 2β-hydroxymethyl tetraeicosanoate (8). Tetradecane (9), four fatty acids: hexadecanoic acid (10), tetradecanoic acid (11), (Z)-9-eicosenoic acid (12), and ethyl tetradec-7-enoate (13) were isolated from chloroform extract of Turraea vogelii stem. 1,2,3-propanetriyltris(heptadecanoate) (14), (Z)-9-octadecenoic acid (15) and (Z)-7-tetradecenoic acid (16) were isolated from ethyl acetate extract while (Z)-5-pentadecenoic acid (17) was obtained from methanol extract of the plant stem. Compounds 1, 2, 5, 6, 11, 12, 15, 16 and 17 exhibited pronounced antiproliferative activity against K-562 cell lines.     

Experimental and theoretical assessment of Fe-doped indium-oxide-based dilute magnetic semiconductors

Specimens of iron-doped indium oxide (In_1-xFe_x)₂O₃ with x?=?0.015, 0.03, 0.045 and 0.06, amalgamated through a traditional solid-state reaction method followed by H₂/air sintering, were characterised using an X-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscope (SEM) to investigate their structural, magnetic and morphological properties respectively. According to XRD plots, all the specimens exhibit cubic bixbyite structures along with ancillary phases. Magnetic assessment showed that In₂O₃ has a negative susceptibility, exhibiting diamagnetic behaviour at room temperature. The doping of Fe ions induces ferromagnetic (FM) ordering, which is enhanced with increasing doping content. The strength of the magnetisation increases when the specimens are exposed to H₂ but is reduced on further air sintering. A bound magnetic polaron (BMP) model is successfully fitted to the observed FM data involving localised carriers and magnetic cations. A multivariate assessment viz. a hierarchical cluster analysis (HCA) was used to corroborate and strengthen the experimental determined magnetic properties. A homogeneous particle distribution was observed in all SEM micrographs and is validated through MATLAB-based simulation by applying a watershed segmentation algorithm. Surface plots also confirm the change in magnetic properties with increase in doping concentration.     

High-Throughput GC-FID Method for the Determination of Residual Solvents in Early-Phase Drug Discovery Samples

Chromatographia - In drug discovery environment, determination of residual solvents is indispensable and requires rapid analysis covering a maximum number of commonly used solvents especially with...     

Tertiary-butoxycarbonyl (Boc) – A strategic group for N-protection/deprotection in the synthesis of various natural/unnatural N-unprotected aminoacid cyanomethyl esters

A number of cyanomethyl esters of natural/unnatural aminoacids with un-protected amino functionality were synthesized because of their synthetic and medicinal importance. Critical N-Boc deprotection methods in the presence of labile (hydrolytic sensitivity) cyanomethyl functionality were screened thoroughly and it was found that readily available 4M HCl in 1,4-dioxane solution (2–4 equiv); acetonitrile, 0?°C, 2–4?h was a suitable condition. This condition was generalized and successfully applied to a variety of alkyl, alkynyl, aryl, heteroaryl, benzyl, azido, spiro amino acid cyanomethylesters irrespective of the nature of the amine (primary or secondary) and the distance between the amine and ester group to achieve final deprotected amino esters with high yield, and purity compared to other commonly known N-protecting groups (Cbz, Fmoc, Ac, Bn, Bz etc.). It was also demonstrated that N-Boc protected aminoacid cyanomethylesters are stable enough to carry out further functionalization compared to N-unprotected counterparts.     

Control of crystal growth in bridgman furnace

Control of crystal quality during crystal growth requires accurate implementation of thermal boundary conditions. We identify this problem as the furnace temperature control problem. The thermal boundary conditions, in turn, dictate the interface shape between the solid and the liquid region of the material. Determination of the boundary conditions for a given desired interface shape is considered as the material temperature control problem in this paper. We outline the current efforts for the solution of the furnace temperature control and the material temperature control problems. We restrict our review to Bridgman growth control techniques.     

Effect of pressure drop on solute retention and column efficiency in supercritical fluid chromatography. Part 2: Modified carbon dioxide as mobile phase

The effect of pressure drop on the performance of supercritical fluid chromatography systems using a modified mobile phase (carbon dioxide + ethanol) was studied. Experiments were performed on a Lichrospher-RP-18 column with phenanthrene as a solute. A wide range of back pressures (130 to 210 bar) and modifier concentrations (2 to 7% w/w) have been explored. Experiments yielding both small and large pressure drops were performed. From these experiments, parameters to describe pressure drop, retention, and column efficiency were extracted, and were used to simulate the dynamics of the chromatographic column. A good match between the experimentally measured and calculated values of pressure drop, retention times, and column efficiency was observed. At low back pressure and modifier composition, significant loss of column efficiency was observed.     

Synthesis and properties of mononuclear and binuclear molybdenum complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

The monomer molybdenum(VI) complex [MoO(2)(napoxlhH(2))].2H(2)O (1) has been synthesized from the reaction of MoO(2)(acac)(2) with bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (napoxlhH(4)) in 1:1 molar ratio in ethanol under reflux. This complex on reaction with pyridine/3-picoline/4-picoline yielded the dimer molybdenum(VI) complexes [Mo(2)O(4)(napoxlhH(2))(2)(A)(2)].2H(2)O (A=py (2), 3-pic (3), 4-pic (4)), whereas reaction with isonicotinoylhydrazine (inhH(3)) and salicyloylhydrazine (sylshH(3)) lead to the reduction of the metal centre yielding monomeric molybdenum(V) complexes [Mo(napoxlhH(2))(hzid)].2H(2)O (where hzidH(3)=inhH(3) (5) and sylshH(3) (6)). The complexes have been characterized by elemental analyses, molecular weight determinations, molar conductance data, magnetic moment data, electronic, IR, ESR and (1)H NMR spectroscopic studies. The complexes (5) and (6) are paramagnetic to the extent of one unpaired electron. The electronic spectra of the complexes are dominated by strong charge transfer bands. In all of the complexes, the principal dihydrazone ligand has been suggested to coordinate to the metal centres in the anti-cis-configuration. The complexes (1), (5) and (6) are suggested to have six-coordinate octahedral stereochemistry around molybdenum(VI) and molybdenum(V) metal centres, respectively, while the complexes (2)-(4) are suggested to have eight coordinate dodecahedral stereochemistry around molybdenum(VI) metal centre.