Characteristics investigation on heat transfer growth of sonochemically synthesized ZnO-DW based nanofluids inside square heat exchanger

Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers...     

The effect of rapid rotation on a vertical bridgman furnace at large Rayleigh number

In quasi-steady operation, convection currents in a Bridgmandevice, used for producing a semi-conductor crystal, createinhomogeneities that may make the crystal unusable. It has oftenbeen suggested that additional forces due to rotation or magnetismmight be efficacious in reducing the segregation of the elementsof the alloy. It has been found that, over a wide range of rotationrates, there is no improvement in performance due to rotationabout the vertical axis. However, numerical results that havebeen obtained previously (Lee & Pearlstein, J. Crys. Growth240, 2002) indicate that, when effects of centrifugal buoyancyare introduced, a substantial reduction in segregation is achieved.In the work reported here, by contrast, in which we extend previouslarge-Rayleigh-number asymptotic analysis to include centrifugalbuoyancy, we find no improvement in radial segregation, butrather increasing segregation with increasing rotation rate.     

Di‐2‐pyridyl ketone N4,N4‐(butane‐1,4‐diyl)thiosemicarbazone

The title compound, C₁₆H₁₇N₅S, is in the thione form and crystallizes with two independent mol­ecules in the asymmetric unit. In both mol­ecules, the penta­methyl­ene­imine five‐membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C—N bond.     

Kinetics of the enzymatic saccharification of pretreated tapioca waste (Manihot esculenta) and water hyacinth (Eichhornia crassipes)

Studies were carried out on saccharification of pretreated tapioca waste and water hyacinth under two different conditions: using microbial enzymes (cellulase fromMyrothecium verrucaria, Coprinus comatus,Pleurotus florida, andCellulomonas sp.) and solid-state fermentation. The rate of saccharification was determined at different temperatures, pH, substrate concentration, and incubation period. It was found that as the source of the enzyme varies, the optimal temperature and pH for the saccharification varies. Among the two different treatments, enzymatic saccharification was found to be the most efficient. Among the various cellulase sources tested, M.verrucaria cellulase was found to be the most efficient one followed byC. comatus, P. florida, and finallyCellulomonas sp.     

2‐Hydro­xy‐3‐(4,5,6,7‐tetra­hydro‐1H‐imidazo­[4,5‐c]­pyridin‐5‐ium‐4‐yl)­benzoate monohydrate

The title mol­ecule, C₁₃H₁₃N₃O₃·H₂O, is in the form of a mono­hydrated zwitterion. The tetra­hydro­pyridinium ring adopts an envelope conformation and is nearly coplanar with the plane of the imidazoline ring. The water solvate mol­ecule plays an important role as a bridge between zwitterions, forming molecular chains running along the c direction, which are interconnected by N—H?O hydrogen bonds into molecular ribbons. The crystal packing is further stabilized by another N—H?O and one O—H?N hydrogen bond, which interconnect the molecular ribbons.     

Pretreatment studies of cellulose wastes for optimization of cellulase enzyme activity

The composition of cellulose, hemicellulose, starch, lignin, pectin, protein, and total lipid content in the selected cellulosic wastes-tapioca (Manihot esculenta) stem, leaf, petiole, and water hyacinth (Eichhornia crassipes) were determined. The effectiveness of various physical and chemical pretreatments on the enzymatic digestibility of these wastes were identified. In general, chemical pretreatments were more effective than physical pretreatments. The efficiency of the pretreatment was checked by subjecting these wastes to enzymatic saccharification after the pretreatments.     

An insight into the potent antioxidant activity of a dithiocarbohydrazone appended cis-dioxidomolybdenum (VI) complexes

In search of antioxidants with enriched potency, the present study focus on the design and synthesis of a dithiocarbohydrazone, H₃TCL derived from thiocarbohydrazide and 3-ethoxysalicylaldehyde and its coordination complexes with molybdenum, viz, [MoO₂(HTCL)D] ( 1 – 2 ) (where D = methanol ( 1 ), DMSO ( 2 )) and [MoO₂(HTCL)D]·DMF (where D = H₂O ( 3 )). The synthesized compounds were characterised by elemental analysis, spectroscopic techniques (FT-IR, UV–vis and ¹H-NMR), conductivity measurements and cyclic voltammetry. Moreover the solid state structures of all the three complexes were established by single crystal X-ray diffraction analysis as mononuclear neutral species in which the molybdenum centre assumes a distorted octahedral geometry. The dithiocarbohydrazone binds to the molybdenum centre through its phenolate oxygen, O(1), azomethine nitrogen, N(1) and thioenolate sulfur, S(1) in a dianionic tridentate mode. The assessment of intermolecular contacts in the crystal arrangement was quantified using Hirshfeld surface analysis. Further the antioxidant potential of the dithiocarbohydrazone, H₃TCL and its molybdenum complexes 1 – 3 were evaluated using 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and total antioxidant assays. The antioxidant activities were then compared with standard antioxidant, L-ascorbic acid. The antioxidant potential of the synthesized compounds were then validated by molecular docking studies. Molecular modelling study was achieved to evaluate the recognition of target compound at the binding pocket of the human antioxidant enzyme, 3MNG. The docking results showed that the complexes selectively bond to the vital amino acids present in the binding pocket of the target enzyme, 3MNG.     

In vitro biomolecular interaction studies and cytotoxic activities of copper(II) and zinc(II) complexes bearing ONS donor thiosemicarbazones

Among all the bio‐metals, zinc and copper derivatives of ONS donor thiosemicarbazone have aroused great interest because of their potential biological applications. Multisubstituted thiosemicarbazone ligand H₂dspt (3,5‐dichlorosalicylaldehyde‐N⁴‐phenylthiosemicarbazone) derived new ternary complexes like [Zn(dspt)(phen)]?DMF ( 1 ) and [Cu(dspt)(phen)]?DMF ( 2 ), and another thiosemicarbazone, H₂dsct (3,5‐dichlorosalicylaldehyde‐N⁴‐cyclohexylthiosemicarbazone), derived [Cu(dsct)(bipy)]?DMF ( 3 ). These complexes have been characterized by elemental analysis (CHNS), Fourier transform infrared (FT‐IR), ultraviolet–visible (UV–Vis) and proton nuclear magnetic resonance (¹H‐NMR) spectra. The structures of the complexes were obtained by single‐crystal X‐ray diffraction analysis. Compounds 1 and 2 got crystallized in the monoclinic P2₁/c space group. The complexes showed interesting supramolecular interaction, which in turn stabilizes the complexes. The ground state electronic configurations of the complexes were studied using the B3LYP/LANL2DZ basis set, and ESP plots of complexes were investigated. The interaction of the complexes with calf thymus DNA (CT‐DNA) was studied using absorption and fluorescence spectroscopic methods. A UV study of the interaction of the complexes with calf thymus DNA (CT‐DNA) has shown that the complexes can effectively bind to CT‐DNA, and [Cu(dspt)(phen)]·DMF ( 2 ) exhibited the highest binding constant to CT‐DNA (K_b = 3.7 × 10⁴). Fluorescence spectral studies also indicated that Complex 2 binds relatively stronger with CT DNA through intercalative mode, exhibiting higher binding constant (K_q = 4.7 × 10⁵). The DNA cleavage result showed that the complexes are capable of cleaving the DNA without the help of any external agent. Molecular docking studies were carried out to understand the binding of complexes with the molecular target DNA. Complex 2 exhibited the highest cytotoxicity against human breast cancer cell line MD‐MBA‐231 (IC₅₀ = 23.93 μg/mL) as compared to Complex 1 (IC₅₀ = 44.40 μg/mL) .     

Synthesis,Spectral and Structural Studies of a Novel Semicarbazone Synthesized from Quinoline-2-Carboxaldehyde and N<Superscript>4</Superscript>-Phenyl-3-Semicarbazide

Abstract  

A new semicarbazone, HL has been synthesized from quinoline-2-carboxaldehyde and N⁴-phenyl-3-semicarbazide and structurally and spectrochemically characterized. ¹H NMR, ¹³C NMR, IR and electronic spectra of the compound are studied. The existence of keto form in the solid state is supported by the crystal structure and IR data. The compound crystallizes into an orthorhombic space group P2₁2₁2₁. Intra and intermolecular hydrogen bonding interactions facilitates unit cell packing in the crystal lattice.     

Controlled hydrothermal growth of ZnO nanostructures by sequestering the Zn metal ions with the chelating agent EDTA

In the present work, a controlled growth of ZnO nanostructures by manipulating Zn metal ion concentration by the chelating action of ethylene diaminetetra acetic acid in hydrothermal method is studied. EDTA produces metal–chelate complex by the formation of bidentate ligand with Zn²⁺ in the solution and diminishes the reactivity of Zn metal cations. Concentration of EDTA in the mother solution was varied in different ranges like 3, 5 and 10 mM while retaining the zinc metal salt and the NaOH concentration the same. Three different morphologies of wurtzite structured ZnO nanostructures such as nanorods-bunch, separate/discrete uniformly sized hexagonal nanorods and tapered flower petals like shapes are achieved by 3, 5 and 10 mM strengths of EDTA, respectively. The medium concentration 5 mM of EDTA is found to have moderate control over producing ZnO nanostructures of uniform diameter and a high aspect (length to diameter) ratio. An array of vertically aligned free standing ZnO nanorods with uniform spacing is successfully achieved by the addition of 5 mM of EDTA in the mother solution and the same is studied for its fluorescence property at an excitation of 325 nm and it has exhibited a characteristic UV emission of ZnO around 383 nm.