The first ionic liquid-promoted three-component coupling strategy for an expeditious synthesis of β-nitrocarbonitriles/thiocyanates

A novel and convenient three-component coupling reaction of nitromethane, aromatic aldehydes and trimethylsilyl cyanide (TMSCN) or ammonium thiocyanate has been developed for an expeditious synthesis of β-nitrocarbonitriles or β-nitrothiocyanates, respectively, via C-C and C-S bond-forming reactions. The synthetic protocol strategically involves a one-pot sequential Henry reaction and a Michael addition efficiently promoted by the same ionic liquid [bmim]OH. The main advantages of the present approach include the use of inexpensive simple substrates and an ionic liquid as an efficient reaction promoter for the mild synthesis in a one-pot procedure.     

Design and analysis of a BLPC vocoder-based adaptive feedback cancellation with probe noise

The band-limited linear predictive coding (BLPC) vocoder-based adaptive feedback cancellation (AFC) removes the high-frequency bias, while the low frequency bias persists between the desired input signal and the loudspeaker signal in the estimate of the feedback path. In this paper, we present a BLPC vocoder-based adaptive feedback canceller with probe noise with an objective of reducing the low-frequency bias in digital hearing-aids. A step-wise mathematical analysis of the proposed feedback canceller is presented employing the recursive least square and normalized least mean square adaptive algorithms. It is observed that the optimal solution of the feedback path is unbiased for an unshaped probe noise, but is biased for a shaped probe signal; the bias term does not consist of correlation between the desired input and the loudspeaker output. The identifiability conditions are analysed and it is shown that a delay, greater than or equal to the length of the adaptive filter, must be introduced in the forward path to achieve an unbiased feedback path estimate. Algorithm analysis and computer simulations presented in this paper justify the reason for selecting the proposed design over the existing BLPC vocoder-based feedback cancellation algorithm.     

NHC-catalysed diastereoselective synthesis of multifunctionalised piperidines via cascade reaction of enals with azalactones

NHC-catalysed azalactone ring-opening and piperidine ring-closing cascade with α,β-unsaturated aldehydes (enals) in a one-pot operation is reported. The present reaction cascade offers a convenient method for a highly diastereoselective synthesis of multifunctionalised piperidines in excellent yields under mild conditions.     

Aqua mediated indium(III) chloride catalyzed synthesis of fused pyrimidines and pyrazoles

The utilization of water as solvent and indium trichloride as promoter for the three-component combinatorial synthesis of a variety of bioactive pyrimidine and pyrazole derivatives (2–10) from aldehydes, 1,3-dicarbonyl compounds, and electron-rich amino heterocycles like 6-amino-1,3-dimethyl uracil and 3-methyl-1-phenyl-1H-pyrazol-5-amine catalyzed by indium trichloride under reflux has been studied. A new class of pyrimidine derivatives (2) has also been synthesized and the structure was confirmed by single crystal X-ray analysis. The reactions are environmentally benign, reaction product could be isolated easily and the catalyst could be recycled, which makes it an appealing synthetic protocol.     

Semisynthesis of Functional Glycosylphosphatidylinositol-Anchored Proteins

Glypiation is a common posttranslational modification of eukaryotic proteins involving the attachment of a glycosylphosphatidylinositol (GPI) glycolipid. GPIs contain a conserved phosphoglycan that is modified in a cell- and tissue-specific manner. GPI complexity suggests roles in biological processes and effects on the attached protein, but the difficulties to get homogeneous material have hindered studies. We disclose a one-pot intein-mediated ligation (OPL) to obtain GPI-anchored proteins. The strategy enables the glypiation of folded and denatured proteins with a natural linkage to the glycolipid. Using the strategy, glypiated eGFP, Thy1, and the Plasmodium berghei protein MSP1₁₉ were prepared. Glypiation did not alter the structure of eGFP and MSP1₁₉ proteins in solution, but it induced a strong pro-inflammatory response in vitro. The strategy provides access to glypiated proteins to elucidate the activity of this modification and for use as vaccine candidates against parasitic infections.     

An efficient strategy for N-alkylation of benzimidazoles/imidazoles in SDS-aqueous basic medium and N-alkylation induced ring opening of benzimidazoles

A sustainable route for the N-1 alkylation of imidazole and benzimidazole derivatives has been developed under volatile organic solvent free condition in alkaline water-SDS system. Incorporation of SDS in the reaction medium enhances the reaction rate by suppressing the solubility issue that arises for different substrates. This method provides high yield of the alkylated product in a shorter reaction time. For reactive alkyl halides reaction proceeds at ambient temperature whereas in the cases of less reactive alkyl halides require 55–60?°C to complete alkylation process. N-alkylation induced ring opening of the heterocyclic ring in benzimidazole derivatives to multifunctional aromatic compounds were noticed at 60?°C when more than two equivalents of alkyl halide was used.     

Metal oxides nanocomposite membrane for biofouling mitigation in wastewater treatment

These days our one of the major challenges is the treatment of polluted wastewater produced by the growing population and industrial activities. The conventional wastewater treatment methods are costly and need to be more advanced. For this reason, membrane technology has been used as an effective wastewater treatment method for many decades due to its high removal power, selectivity, and permeability properties. Biofouling causes a serious concern related to membrane permeability, shortens membrane life, and selectivity. Polymeric membranes are widely used in wastewater treatment due to their good pore-forming ability, higher flexibility, and relatively low costs but are limited to their hydrophobicity property and more susceptible to fouling. Metal oxides nanomaterials are widely used in the formation of polymer nanocomposite membranes because of their hydrophilicity, larger surface area, pore channels, and high toxicity towards pathogenic micro-organisms. In this review, we have discussed the factors affecting membrane biofouling and their conventional and current treatment methods with their limitations. We have also referred to the use of metal oxide nanomaterials, as an antibacterial agent, for the fabrication of polymer nanocomposite membranes and discuss their antibacterial activity with antibiofouling behavior.     

Zwitterionic Character and Lipid Composition Determine the Behaviour of Glycosylphosphatidylinositol Fragments in Monolayers

Glycosylphosphatidylinositols (GPIs) are complex glycolipids found in free form or anchoring proteins to the outer leaflet of the cell membrane in eukaryotes. GPIs have been associated with the formation of lipid rafts and protein sorting on membranes. The presence of a conserved glycan core with cell-specific modifications together with lipid remodelling during biosynthesis suggest that the properties of the glycolipids are being fine-tuned. We synthesized a series of GPI fragments and evaluated the interactions and arrangement of these glycolipids in monolayers as a 2-D membrane model. GIXD and IRRAS analyses showed the need of N-acetylglucosamine deacetylation for the formation of hydrogen bonds to obtain highly structured domains in the monolayers and an effect of the unsaturated lipids in formation and localization of the glycolipids within or between membrane microdomains. These results contribute to understand the role of these glycolipids and their modifications in the organization of membranes.     

Bio-Assisted Preparation of Nano Zinc Oxide and Its Behavior Towards Textile Azo Pollutants

High Energy Chemistry - Recent reports on nanoparticles rise significantly as they possess numerous applications in medical, material science, optics, and bioscience etc. Nanoparticles show unique...     

Recent advances and spectroscopic perspectives in fluoride removal

With the constant rising demand for pure water to meet the needs of the growing population particularly in developing countries, fluoride remediation from drinking water has emerged as an increasingly important matter of public concern. In the past decade, significant efforts and advances have been made for developing efficient adsorbents for fluoride removal from water. This review summarizes recent advances (2012–2016) in defluoridation techniques and highlights the challenges and opportunities for future research in the important field of fluoride removal. The spectroscopic techniques, used to develop adsorbents/adsorption mechanism, discussed in this review are X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, inductively coupled plasma mass spectrometry, atomic absorption spectrometry, inductive coupled plasma-optical emission spectroscopy, and X-ray photoelectron spectroscopy. The defluoridation techniques have been discussed in four categories: precipitation, membrane, ion-exchange, and adsorption techniques. Then recent research on fluoride removal using various adsorbents with their spectroscopic studies are summarized and discussed with regard to their synthetic chemistry, properties, and applications. The advantages and disadvantages of defluoridation techniques and adsorbents have been presented. Finally, the future needs and perspectives of fluoride removal are addressed.