Characterization,Analysis, and Application of Fabricated Fe3O4-Chitosan-Pectinase Nanobiocatalyst

The investigation on fabrication of Fe₃O₄-chitosan-pectinase nanobiocatalyst was performed by covalently binding the pectinase onto carboxyl group activated chitosan-coated magnetic nanoparticles (CMNPs). The morphological and size distribution analysis of the different magnetic nanoparticles (MNPs) was done using transmission electron microscopy (TEM), and the average diameter was 11.07?±?3.04, 11.55?±?3.16, and 11.59?±?3.16 nm for MNPs, CMNPs, and fabricated nanobiocatalyst, respectively, suggesting that there was no significant change in the size of MNPs after coating and binding. The characteristic peaks occurred at 2θ of 30.39, 35.43, 43.37, 57.22, and 62.9, and their corresponding indices 220, 311, 400, 520, and 441 for different MNPs from the X-ray diffraction (XRD) studies confirmed the presence of Fe₃O₄ with the spinel structure, and there was no phase change even after coating and binding. The various required characteristic absorption peaks (575, 585, 1,563, 1,614, 1,651, and 1,653 cm^?1) from Fourier transform infrared (FT-IR) spectroscopy confirmed the surface modifications and binding of pectinase onto the MNPs. At the weight ratio of about 19.8?×?10^?3 mg bound pectinase/mg activated CMNPs, the activity of fabricated nanobiocatalyst was found to be maximum. In order to monitor their improved activity, the pH, temperature, reusability, storage ability, and kinetic studies were established.     

Rapid screening of N-oxides of chemical warfare agents degradation products by ESI-tandem mass spectrometry

Rapid detection and identification of chemical warfare agents and related precursors/degradation products in various environmental matrices is of paramount importance for verification of standards set by the chemical weapons convention (CWC). Nitrogen mustards, N,N-dialkylaminoethyl-2-chlorides, N,N-dialkylaminoethanols, N-alkyldiethanolamines, and triethanolamine, which are listed CWC scheduled chemicals, are prone to undergo N-oxidation in environmental matrices or during decontamination process. Thus, screening of the oxidized products of these compounds is also an important task in the verification process because the presence of these products reveals alleged use of nitrogen mustards or precursors of VX compounds. The N-oxides of aminoethanols and aminoethylchlorides easily produce [M + H]⁺ ions under electrospray ionization conditions, and their collision-induced dissociation spectra include a specific neutral loss of 48 u (OH + CH₂OH) and 66 u (OH + CH₂Cl), respectively. Based on this specific fragmentation, a rapid screening method was developed for screening of the N-oxides by applying neutral loss scan technique. The method was validated and the applicability of the method was demonstrated by analyzing positive and negative samples. The method was useful in the detection of N-oxides of aminoethanols and aminoethylchlorides in environmental matrices at trace levels (LOD, up to 500 ppb), even in the presence of complex masking agents, without the use of time-consuming sample preparation methods and chromatographic steps. This method is advantageous for the off-site verification program and also for participation in official proficiency tests conducted by the Organization for the Prohibition of Chemical Weapons (OPCW), the Netherlands. The structure of N-oxides can be confirmed by the MS/MS experiments on the detected peaks. A liquid chromatography-mass spectrometry (LC-MS) method was developed for the separation of isomeric N-oxides of aminoethanols and aminoethylchlorides using a C18 Hilic column. Critical isomeric compounds can be confirmed by LC-MS/MS experiments, after detecting the N-oxides from the neutral loss scanning method.

New genetic insights to consider coffee waste as feedstock for fuel,feed, and chemicals

Caffeine is a natural plant product found in many drinks, including coffee, tea, soft and energy drinks. Due to caffeine’s presence in the environment, microorganisms have evolved two different mechanisms to live on caffeine. The genetic maps of the caffeine N-demethylation pathway and C-8 oxidation pathway have been discovered in Pseudomonas putida CBB5 and Pseudomonas sp. CBB1, respectively. These genes are the only characterized bacterial caffeine-degrading genes, and may be of great value in producing fine chemicals, biofuels, and animal feed from coffee and tea waste. Here, we present preliminary results for production of theobromine and 7-methylxanthine from caffeine and theobromine, respectively, by two strains of metabolically engineered E. coli. We also demonstrate complete decaffeination of tea extract by an immobilized mixed culture of Klebsiella and Rhodococcus cells. These processes provide a first level demonstration of biotechnological utilization of coffee and tea waste.      

A new protocol to synthesize 1,4-dihydropyridines by using 3,4,5-trifluorobenzeneboronic acid as a catalyst in ionic liquid: synthesis of novel 4-(3-carboxyl-1H-pyrazol-4-yl)-1,4-dihydropyridines

3,4,5-Trifluorobenzeneboronic acid catalysed, ionic liquid mediated facile synthesis of 4-pyrazolyl 1,4-dihydropyridines at room temperature by the cyclocondensation of ethyl 3-aminocrotonate, pyrazole aldehyde and a β-keto ester is reported. The procedure adopted was found to be eco-benign, facile at room temperature and better than the conventional, [bmim]Cl mediated and InCl₃ catalysed, [bmim]Cl mediated 1,4-dihydropyridine syntheses.     

Measurement of extensional viscosity of polymer solutions

A filament stretching technique for measuring the extensional viscosity of polymer solutions at constant stretch rate is presented. The liquid sample is held between two coaxial discs and stretched by moving the bottom disc downwards with a speed that increases exponentially with time. This is illustrated using a constant viscosity, elastic fluid consisting of 0.185% polyisobutylene in a solvent of kerosene and polybutene. For the case of this particular fluid, two distinct stretch rate regions are found to arise. The stretch rate in the first region is much higher than in the second, which is, in most cases, close to the overall stretch rate imposed on the sample. Nonetheless, all the results of any given run can be represented using an average extensional rate. The extensional stress growth data, plotted as the Trouton ratio against time, show an initial linear viscoelastic region where T_R rises to a value of 3, independent of extensional rate. Beyond this region, T_R depends on the stretch rate and rises dramatically to values in excess of 10³; the higher the extensional rate, the faster is the increase in T_R. These data do not seem to reach a steady state and appear to be similar to polymer melt data obtained by others in the past. The reproducibility of the results is very good and all this suggests that it is now possible to obtain unambiguous constant-stretch-rate stress-growth data for polymer solutions stretched from a state of rest.     

An efficient synthesis of conjugated nitro-olefins using ceric ammonium nitrate

An efficient method for the synthesis of conjugated nitro-olefins from α,β-unsaturated acids under extremely mild conditions using ceric ammonium nitrate (CAN) at room temperature in acetonitrile in moderate to good yields is described.     

Two quinazolinones: a ring conformational study

The molecules of (±)‐2‐(4‐methoxyphenyl)‐1‐phenethyl‐2,3‐dihydroquinazolin‐4(1H)‐one, C₂₃H₂₂N₂O₂, (I), and (±)‐2‐(1,3‐benzodioxol‐5‐yl)‐1‐phenethyl‐2,3‐dihydroquinazolin‐4(1H)‐one, C₂₃H₂₀N₂O₃, (II), have T‐shaped forms in the crystal structure. The tetrahydropyrimidine ring in both structures adopts a sofa conformation. Both molecules are linked by N—H...O and C—H...O hydrogen bonds to form sheets built from alternating R₂²(8) and R₄⁴(26) [R₄⁴(24) in (II)] edge‐fused rings. Additionally, the structures are stabilized by extensive C—H...π interactions.     

Rh(III)-Catalyzed Oxidative Annulation of 2-Arylquinoxalines with Cyclic 2-Diazo-1,3-diketones by C−H Bond Activation

Rh(III)-catalyzed C−H bond annulation of 2-arylquinoxalines with cyclic 2-diazo-1,3-diketones has been accomplished for the first time to synthesize a novel series of 2,3-dihydrodibenzo[a,c]phenazin-4(1H)-one frameworks by means of carbene insertion followed by condensation. The reaction proceeds through the C−H bond activation and functionalization of 2-arylquinoxalines using Rh(III)/AgSbF₆ complex to produce highly substituted 2,3-dihydrodibenzo[a,c]phenazin-4(1H)-one and benzo[5,6][1,2,4]thiadiazino[2,3-f]phenanthridin-5(6H)-one-10,10-dioxide derivatives in good to excellent yields.