Synthesis, Structural Characterization, and Biological Activities of Organically Templated Cobalt Phosphite (H2DAB)[Co(H2PO3)4]·2H2O

A novel hybrid cobalt phosphite, (H2DAB)[Co(H2PO3)4]·2H2O, has been synthesized by using slow evaporation method, in the presence of cobalt nitrate, phosphorous acid and 1,4- dia-minobutane (DAB= 1,4- diaminobutane) as a structure-directing agent. Single crystal X-ray diffraction analysis showed that the compound crystallizes in the P-1(n.2) triclinic space group, with the following unit cell parameters (Å, °) a = 5.4814 (3), b = 7.5515 (4), c = 10.8548 (6), α = 88.001 (4), β = 88.707 (5), γ = 85.126 (5), and V= 447.33 (4) Å3. The crystal structure was built up from cor-ner-sharing [CoO6] octahedra, forming chains parallel to [001], which are interconnected by H2PO3 pseudo-tetrahedral units. The deprotonated cations, residing between the parallel chains, interacted with the inorganic moiety via hydrogen bonds leading thus to the formation of the 3D crystal structure. The Fourier transform infrared spectrum showed characteristic bands corresponding to the phosphite group and the organic amine. The thermal behavior of the compound consisted mainly of the loss of its organic moiety and the water molecules. The biological tests exhibited significant activity against Candida albicans and Escherichia coli strains in all used concentrations, while less inhibitory activity was pronounced against Staphylococcus epidermidis and Saccharomyces cerevisiae, and in the case of multi-cellular organisms, no activity against the nematode model Steinernema feltiae was detected.

EFFECT OF NUTRIENTS ON CELLULOLYTIC AND PECTOLYTIC ENZYME PRODUCTION OF ALTERNARIA ALTERNATA A LEAF SPOT PATHOGEN OF TEAK (TECTONA GRANDIS L.F.)

Alternaria alternata is a potential pathogen of Tectona grandis L.f., was isolated from diseased Tectona grandis L.f. leaves from Nashik and used for the present study. Pathogen was grown on the Czapek-Dox liquid medium substituting or adding different carbon, nitrogen to study cellulolytic and pectolytic enzyme production and total phenol production. The activity of enzyme was observed on the 8th day of incubation period. A great extent of growth variation was observed on different carbon, nitrogen. Among the carbon source) the maximum loss in percentage viscosity maximum in lactose and fructose. While minimum in glucose and dextrose as compared to other nitrogen source. From nitrogen source the cellulolytic enzyme activity was maximum in control and cobalt nitrate followed by similar activity in potassium nitrate and nickel nitrate. While minimum cellulolytic enzyme activity was seen in barium nitrate.. Variation was also observe in pectolytic enzyme activity. the cellulolytic enzyme activity was maximum in glucose while minimum in dextrose as compared to lactose, control and fructose.. From nitrogen source the cellulose activity was maximum in potasium nitrate and minimum in cobalt nitrate as compared to nickel nitrate, barium nitrate and control.

Synthesis and Characterization of New Ferrite-Lignin Hybrids

The paper presents the synthesis and characterization of new cobalt ferrite-lignin hybrids. The hybrids were obtained through the combustion of cobalt nitrate and ferric nitrate, two kinds of lignin being used as combustion agents. The temperatures of calcination were 500 °C and 900 °C, respectively. The hybrids were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS). The magnetic properties were also assessed by vibrating sample magnetometer system (VSM). This facile synthesis method made it possible to obtain cobalt ferrite-lignin hybrids with a spinel structure. Their particle sizes and crystallite sizes have increased with an increment in the calcination temperature. A different occupancy of cations at octahedral and tetrahedral sites also occurred upon the increase in temperature. The hybrids comprising organic lignin presented the best magnetic properties.

Fischer-Tropsch Synthesis: The Characterization and Testing of Pt-Co/SiO2 Catalysts Prepared with Alternative Cobalt Precursors

Different low-cost cobalt precursors (acetate, chloride) and thermal treatments (air calcination/H2 reduction versus direct H2-activation) were investigated to alter the interaction between cobalt and silica. H2-activated catalysts prepared from cobalt chloride had large Co0 particles (XRD, chemisorption) formed by weak interactions between cobalt chloride and silica (temperature programmed reduction (TPR), TPR with mass spectrometry (TPR-MS), TPR with extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge spectroscopy (XANES) techniques) and retained Cl-blocked active sites, resulting in poor activity. In contrast, unpromoted Co/SiO2 catalysts derived from cobalt acetate had strong interactions between Co species and silica (TPR/TPR-MS, TPR-EXAFS/XANES); adding Pt increased the extent of the Co reduction. For these Pt-promoted catalysts, the reduction of uncalcined catalysts was faster, resulting in larger Co0 clusters (19.5 nm) in comparison with the air-calcined/H2-activated catalyst (7.8 nm). Both catalysts had CO conversions 25% higher than that of the Pt-promoted catalyst prepared in the traditional manner (air calcination/H2 reduction using cobalt nitrate) and three times higher than that of the traditional unpromoted Co/silica catalyst. The retention of residual cobalt carbide (observed in XANES) from cobalt acetate decomposition impacted performance, resulting in a higher C1–C4 selectivity (32.2% for air-calcined and 38.7% for uncalcined) than that of traditional catalysts (17.5–18.6%). The residual carbide also lowered the α-value and olefin/paraffin ratio. Future work will focus on improving selectivity through oxidation–reduction cycles.

Mesoporous CoOx/C Nanocomposites Functionalized Electrochemical Sensor for Rapid and Continuous Detection of Nitrite

Nitrite is widespread in the environment, and is frequently used as an additive to extend the shelf life of meat products. However, the excess intake of nitrite can be harmful to human health. Hence, it is very important to know and control the content of nitrite in foodstuffs. In this work, by the means of self-assembly induced by solvent evaporation, we used the amphiphilic PEO-b-PS diblock copolymers resol and cobalt nitrate as a template to synthesize ordered mesoporous CoOx/C nanocomposites. Then, the CoOx/C nanocomposites were modified on a glassy carbon electrode (GCE), which showed excellent sensitivity, good selectivity, and a wide detection range for nitrite. Through cyclic voltammetry and current–time techniques, the electrochemical performance of the GCE modified with CoOx/C nanocomposites was analyzed. Under the optimized conditions, we found that anodic currents were linearly related to nitrite concentrations with a regression equation of lp (µA) = 0.36388 + 0.01616C (R2 = 0.9987) from 0.2 µM to 2500 µM, and the detection limit was 0.05 µM. Furthermore, the electrochemical sensor behaved with high reproducibility and anti-interference ability towards various organic and inorganic ions, such as NO3−, SO42−, Cl−, COOH− (Ac−), Na+, K+, Mg2+, and NH4+. Our results indicated that these CoOx/C nanocomposites could be applied in electrochemical sensors for the rapid and sensitive detection of the food preservative nitrite.

Effect of Nutrients on Biomass Production of Helminthosporium Tetramera A Leaf Spot Pathogen of Sugarcane (Saccharum Officinarum)

: Helminthosporium tetramera was a pathogen of Saccharum Officinarum, was isolated from diseased Saccharum Officinarum, leaves from Nashik district and used for the present study. Pathogen was grown on the Czapek-Dox liquid medium substituting or adding different carbon, nitrogen to study biomass production. The growth as dry mycelial biomass was observed on the 8th day of incubation period. A grate extent of growth variation was observed on different carbon, nitrogen. Among the carbon source, fructose shows maximum biomass while glucose with minimum biomass. From nitrogen source cobalt nitrate and barium nitrate shows maximum and control condition with minimum biomass was recorded.

Reporting the magnetic profile of cobalt ferrite nanoparticles at different temperatures

Cobalt ferrite nanoparticles (CFNs) were synthesized using cobalt nitrate hexahydrate and ferric nitrate nonahydrate through a wet chemical method. Various characterization techniques were used to confirm the synthesis of CFNs. The thermal stability, structure, morphology and crystallinity of the synthesized CFNs were determined by thermogravimetric analysis, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results show that the synthesized nanoparticles are stable and crystalline with fine homogenized structure. Vibrating sample magnetometry was used to determine the magnetic properties of the synthesized material. The coercivity was noted to be decreased and the hysteresis loop gradually flattens as the temperature increases toward the Curie temperature.

Enhanced Photocatalytic Activity and Magnetic Properties of CNTs/Sn-doped Co3O4 Nanocomposite

Photocatalysis is a green technology which transforms available photon energy into useful chemical energy. The reaction mechanism is based on the ability to create electron-hole pairs under appropriate light. Semiconductors have attracted great attention in photocatalysts because of their high photosensitivity. Spinel–type cobalt oxide nanorods have been prepared by a simple hydrothermal method using cobalt nitrate as precursor. Sn-doped Co3O4 was composited with carbon nanotubes for better photocatalytic activity. An extensive characterization of the prepared samples was carried out using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometer (VSM) and UV–Visible absorption spectroscopy. The XRD results show the formation of Co3O4 phase with FCC structure, FESEM confirms the nanorods morphology of the cobalt oxide and the VSM taken at room temperature shows an antiferromagnetic behavior. The investigation of photocatalytic activity of Co3O4 based was done by methyl orange dye. At the end, the responsible mechanism of CNT/Sn-CO was discussed.