Synthesis and characterization of sol–gel alumina nanofibers

Abstract Alumina nanofibers of high aspect ratio with surface area of >300 m² g⁻¹ has been prepared successfully in bulk quantities by the sol–gel method. The synthesis parameters including the binary water–alcohol solvent system to aluminium isopropoxide ratio, pH, type of solvent and aging temperature affect the uniformity and formation of nanofibers. It is proposed that alumina nanofibers were formed by the curling of the nanosheets upon condensation after the hydrolysis. The phase evolution of alumina nanofibers from pseudoboehmite to α phase has been shown by XRD and FTIR. ²⁷Al NMR investigations show that the Al atoms are six and four coordinated. The morphology of the alumina nanofibers does not change much as the calcination temperature was increased. In addition, the average pore size increases and the BET surface area decreases as a function of calcination temperature. The thermal behavior of alumina nanofibers was investigated by TGA. Graphical Abstract      

Life in the sabkha: Raman spectroscopy of halotrophic extremophiles of relevance to planetary exploration

The Raman spectroscopic biosignatures of halotrophic cyanobacterial extremophiles from sabkha evaporitic saltpans are reported for the first time and ideas about the possible survival strategies in operation have been forthcoming. The biochemicals produced by the cyanobacteria which colonise the interfaces between large plates of clear selenitic gypsum, halite, and dolomitized calcium carbonates in the centre of the salt pans are identifiably different from those which are produced by benthic cyanobacterial mats colonising the surface of the salt pan edges in the intertidal zone. The prediction that similar geological formations would have been present on early Mars and which could now be underlying the highly peroxidised regolith on the surface of the planet has been confirmed by recent satellite observations from Mars orbit and by localised traverses by robotic surface rovers. The successful adoption of miniaturised Raman spectroscopic instrumentation as part of a scientific package for detection of extant life or biomolecular traces of extinct life on proposed future Mars missions will depend critically on interpretation of data from terrestrial Mars analogues such as sabkhas, of which the current study is an example.     

A new alkylated benzoquinone from rhizomes of Iris kumaonensis

A novel alkylated unsaturated p-benzoquinone designated as 3-[(z)-12'-heptadecenyl]-2-hydroxy-5-methoxy-1,4-benzoquinone was isolated from hexane extract of the rhizomes of Iris kumaonensis and it's structure was confirmed by extensive spectroscopic analysis, IR, MS, HREIMS, 1D, 2D NMR and comparison with the literature data of known compounds.     

Phytochemical studies on the seed extract of Piper nigrum Linn

The petroleum ether extract of dried ground seeds of Piper nigrum Linn. and some column fractions of this extract were subjected to GC and GC-MS analysis, resulting in the identification of fourteen compounds (1-14) by using NIST Mass spectral search program 1998 and the Kovat's retention indices. Ten of the compounds (1, 2, 4-12) are reported for the first time from this plant. All the fractions showed insecticidal activity against the fourth instar larvae of Aedes aegypti and against the fourth instar larvae of Anopheles stephensi Liston, determined by the WHO method.     

Proper orthogonal decomposition of the flow in geometries containing a narrow gap

Geometries containing a narrow gap are characterized by strong quasi-periodical flow oscillations in the narrow gap region. The above mentioned phenomena are of inherently unstable nature and, even if no conclusive theoretical study on the subject has been published, the evidence shown to this point suggests that the oscillations are connected to interactions between eddy structures of turbulent flows on opposite sides of the gap. These coherent structures travel in the direction of homogeneous turbulence, in a fashion that strongly recalls a vortex street. Analogous behaviours have been observed for arrays of arbitrarily shaped channels, within certain range of the geometric parameters. A modelling for these phenomena is at least problematic to achieve since they are turbulence driven. This work aims to address the use of Proper Orthogonal Decomposition (POD) to reduce the Navier–Stokes equations to a set of ordinary differential equations and better understand the dynamics underlying these oscillations. Both experimental and numerical data are used to carry out the POD.     

CuI-catalyzed Coupling Reactions of Aryl Iodides with Amides Using L-Proline and KF/Al2O3

An efficient experimentally simple and inexpensive catalyst system for the selective amidation of aryl iodides using 15 mol% of CuI as catalyst, 15 mol% of L-proline as ligand and KF/Al2O3 as a base in toluene is described.     

Recent strategies in the synthesis of thiophene derivatives: highlights from the 2012–2020 literature

Molecular Diversity - Thiophene-based analogs have been fascinated by a growing number of scientists as a potential class of biologically active compounds. Furthermore, they play a vital role for...     

Nanotechnology in the public eye: the case of Iran,as a developing country

Using survey data, public awareness of and attitudes toward nanotechnology are examined in Iran (N = 759). Iran is a developing country with a national nanotechnology action plan for a ten year period starting from 2003 and has been active in the field of research and development of nanotechnology meanwhile. First, the results show that majority of people are still not familiar with nanotechnology and perceived risks posed by this technology are not considered to be a lot and most people feel its benefits outweigh the risks. The emotions toward this technology are of a hopeful and positive nature and this technology is looked upon favorably in Iran. In particular, our results reveals that although the level of trust is high specially in scientists to communicate the risks with the public, there are a great number who just have some trust not quite a lot of it. Knowing that it is a hard and time-consuming effort to manage a nation’s view on nanotechnology, extensive research as well as collaboration with other countries is needed to effectively communicate the risks in time.