Collective effects by agglomerated debris particles in the backscatter

We present an analysis of backscattered light by agglomerated debris particles whose size is comparable with the wavelength. We consider agglomerates that consist of one or two large central particles and a few relatively small fragments surrounding the particles. We find that for the particles we studied, the attachment of small fragments onto the particles leads to a decrease of the negative polarization branch (NPB) at small phase angles in comparison with the branch produced by the isolated particles. For relatively large agglomerates (with size parameters x about 25) the internal scatter in the agglomerates may produce a secondary minimum of the NPB. In this case the second order of scatter between constituents of aggregates plays the dominant role.     

Efficient and Convenient Protocol for the Synthesis of 3,5-Disubstituted 1,2,4-Oxadiazoles Using HClO4-SiO2 as a Heterogeneous Recyclable Catalyst

Silica-supported perchloric acid (HClO₄-SiO₂) was found to be a new, highly efficient, inexpensive, and reusable catalyst for a rapid and efficient synthesis of various 1,2,4-oxadiazoles with good to excellent yields under solvent-free conditions. The present methodology has been effectively utilized for the synthesis of oxolamine, an anti-inflammatory drug.     

Synthesis of bis-α-amino acids through proline catalyzed asymmetric α-amination of higher homologs of Garner's aldehyde

A very convenient synthesis of bis-α-amino acids from the higher homologs of Garner's aldehyde is reported. The key step is proline catalyzed asymmetric amination of the aldehydes using dibenzylazodicarboxylate. The aldehydes used are either commercially available or can easily be prepared from aspartic or glutamic acid. One of the two chiral centers in the bis-amino acids comes from the aldehyde and the other one is generated through the proline catalyzed reaction, which were high yielding and proceeded with very high diastereoselectivity (93–99%). The reported route offers a general method for the synthesis of the title compounds with desired stereochemical outcome.     

Synthesis and Crystal Structure Analysis of 9-Phenyl-β-carboline

An efficient method is described for the synthesis of 9-phenyl-9H-pyrido[3,4-b]indole and 9-(4-chlorophenyl)-9H-pyrido[3,4-b]indole by employing a catalytic amount of CuI (10 mole%) without any ligand. The single crystal of 9-phenyl-9H-pyrido[3,4-b]indole was produced by crystallization from hexane and ethyl acetate mixture that was investigated by single X-ray diffraction (XRD). The compound crystallizes in monoclinic P21/c space group with unit cell dimensions a = 11.3132(5) Å, b = 12.0061(5) Å, c = 9.2498(4) Å, α = 90°, β = 103.187(3)°, γ = 90°. ¹H and ¹³C NMR, IR, and mass spectroscopic methods of the compounds are also discussed.     

Optimisation of the analytical method for octa-, nona- and deca-brominated diphenyl ethers using gas chromatography–quadrupole mass spectrometry and isotope dilution

An analytical method for higher brominated congeners of polybrominated diphenyl ethers (PBDEs) was optimised using a gas chromatograph equipped with an electron impact ionisation-quadrupole mass spectrometer (GC-EI-qMS) and five native PBDEs and three ¹³C₁₂-labelled congeners in biological and environmental samples (mussels, sediment, dust). In the optimised instrumental conditions, abundance and repeatability improved with increase in temperature of the ion source. The instrumental detection limits (IDLs) for BDE-196, BDE-197, BDE-206, BDE-207 and BDE-209 were 0.1, 0.1, 0.2, 0.3 and 0.6?pg, respectively. When compared to the previous reports, the IDLs were the same as for electron capture negative ionisation (ECNI) or EI-double focusing magnetic sector (EI-Sector) mass spectrometer, indicating that sensitive determination could be achieved using a conventional GC-EI-qMS. Validation of the method was carried out by the analysis of reference materials and mussel samples. We confirmed that the concentrations quantified using this method was in the range of reported values for reference materials. Similar concentrations were found in mussels, which were analysed previously by our group. Thus, we conclude that a conventional GC-EI-qMS can be applied for analysis of higher brominated PBDEs in various environmental and biota matrices.     

A PCA study to determine how features in meteorite reflectance spectra vary with the samples’ physical properties

Meteorites have advanced our knowledge of processes in the Solar System with the application of high precision instruments here on Earth. The study of asteroids, the source of most meteorites, has in turn given us knowledge regarding the large scale evolution of the Solar System. Using the complementary information that asteroids and meteorites give us the story of our cosmic backyard can be more easily read. One efficient way to link meteorites to asteroids is by matching their respective reflectance spectra. There have been few convincing matches because of observational and scale differences as well as an incomplete knowledge of the light scattering physics involved. To better interpret the reflectance data we need to know the dependencies of the reflectance on physical properties and develop techniques for better comparisons of data sets. For these purposes we utilise our own measurements of 26 different meteorites together with spectra available on the NASA PDS.We find that normalisation of reflectance at a wavelength between 1.1 and 1.3 μm gives the closest match of spectra from meteorites common to both data sets. The depth of the spectra bands deepens by similar amounts for different types of surface texture alterations i.e. rock to sawn surface, rock to polished surface and rock to powdered surface. Principal Component Analysis (PCA) is able to easily place carbonaceous chondrites, ordinary chondrites and achondrites into distinct groups using their reflectance spectra. We track the variation of spectral features in principal component space by using a set of meteorite spectra synthesised from mineral and elemental spectra. A spectral agent that reduces the reflectance at all wavelengths is required, in addition to olivine, pyroxene and carbon, to generate a set of synthesised spectra to match the distribution of measured spectra, in principal component space.     

Defining the Role of Isoeugenol from Ocimum tenuiflorum against Diabetes Mellitus-Linked Alzheimer’s Disease through Network Pharmacology and Computational Methods

The present study involves the integrated network pharmacology and phytoinformatics-based investigation of phytocompounds from Ocimum tenuiflorum against diabetes mellitus-linked Alzheimer’s disease. It aims to investigate the mechanism of the Ocimum tenuiflorum phytocompounds in the amelioration of diabetes mellitus-linked Alzheimer’s disease through network pharmacology, druglikeness and pharmacokinetics, molecular docking simulations, GO analysis, molecular dynamics simulations, and binding free energy analyses. A total of 14 predicted genes of the 26 orally bioactive compounds were identified. Among these 14 genes, GAPDH and AKT1 were the most significant. The network analysis revealed the AGE-RAGE signaling pathway to be a prominent pathway linked to GAPDH with 50.53% probability. Upon the molecular docking simulation with GAPDH, isoeugenol was found to possess the most significant binding affinity (−6.0 kcal/mol). The molecular dynamics simulation and binding free energy calculation results also predicted that isoeugenol forms a stable protein–ligand complex with GAPDH, where the phytocompound is predicted to chiefly use van der Waal’s binding energy (−159.277 kj/mol). On the basis of these results, it can be concluded that isoeugenol from Ocimum tenuiflorum could be taken for further in vitro and in vivo analysis, targeting GAPDH inhibition for the amelioration of diabetes mellitus-linked Alzheimer’s disease.     

Enantioselective synthesis of spirooxoindoles via chiral auxiliary (bicyclic lactam) controlled SNAr reactions

A highly efficient enantioselective S(N)Ar reaction of chiral acyl bicyclic lactam with substituted-2,4-dinitrobenzenes was developed, affording products containing quarternary stereogenic centers. They are further utilized towards an enantioselective synthesis of spirooxoindoles.     

Quinoline-3-carboxylates as potential antibacterial agents

The ethyl-2-chloroquinoline-3-carboxylates, 4, were achieved from o-aminobenzophenones in two steps. i.e. initially, the ethyl-2-oxoquinoline-3-carboxylates, 3, were obtained by base-catalyzed Friedlander condensations of o-aminobenzophenones, 1, and diethylmalonate, 2. The 2-chloroquinoline-3-carboxylates, 4, were then obtained by the reaction with POCl₃ in good yields. The chemical structures were confirmed by FTIR, mass and ¹H-NMR spectroscopic techniques. All the synthesized compounds were tested for their in vitro antibacterial activity against Bacillus subtilis and Vibrio cholera and found to possess moderate activity.