FT‐Raman and FT‐IR spectral and quantum chemical studies on some flavonoid derivatives: Baicalein and Naringenin

In this study, the experimental and theoretical results on the molecular structures of some flavonoid derivatives (Baicalein and Naringenin) are presented. The FT‐IR and FT‐Raman spectra of the compounds have been recorded together for the first time between 4000–400 cm⁻¹ and 3500–5 cm⁻¹ regions, respectively. The molecular geometry and vibrational wavenumbers of the compounds have been also calculated in their ground states by using ab initio HF and DFT/B3LYP functional with 6‐31G(d,p) basis set used in calculations. The calculations were utilized to the C₁ symmetries of the molecules. All calculations were performed with Gaussian 98 software. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. Scale factors have been used in order to compare how the calculated and experimental data are in agreement. Theoretical infrared intensities were also reported. Copyright © 2008 John Wiley & Sons, Ltd.     

From single to multiple microcoil flow probe NMR and related capillary techniques: a review

Nuclear magnetic resonance (NMR) spectroscopy is one of the most important and powerful instrumental analytical techniques for structural elucidation of unknown small and large (complex) isolated and synthesized compounds in organic and inorganic chemistry. X-ray crystallography, neutron scattering (neutron diffraction), and NMR spectroscopy are the only suitable methods for three-dimensional structure determination at atomic resolution. Moreover, these methods are complementary. However, by means of NMR spectroscopy, reaction dynamics and interaction processes can also be investigated. Unfortunately, this technique is very insensitive in comparison with other spectrometric (e.g., mass spectrometry) and spectroscopic (e.g., infrared spectroscopy) methods. Mainly through the development of stronger magnets and more sensitive solenoidal microcoil flow probes, this drawback has been successfully counteracted. Capillary NMR spectroscopy increases the mass-based sensitivity of the NMR spectroscopic analysis up to 100-fold compared with conventional 5-mm NMR probes, and thus can be coupled online and off-line with other microseparation and detection techniques. It offers not only higher sensitivity, but in many cases provides better quality spectra than traditional methods. Owing to the immense number of compounds (e.g., of natural product extracts and compound libraries) to be examined, single microcoil flow probe NMR spectroscopy will soon be far from being sufficiently effective as a screening method. For this reason, an inevitable trend towards coupled microseparation–multiple microcoil flow probe NMR techniques, which allow simultaneous online and off-line detection of several compounds, will occur. In this review we describe the current status and possible future developments of single and multiple microcoil capillary flow probe NMR spectroscopy and its application as a high-throughput tool for the analysis of a large number of mass-limited samples. The advantages and drawbacks of different coupled microseparation–capillary NMR spectroscopy techniques, such as capillary high-performance liquid chromatography–NMR spectroscopy, capillary electrophoresis–NMR spectroscopy, and capillary gas chromatography–NMR spectroscopy, are discussed and demonstrated by specific applications. Another subject of discussion is the progress in parallel NMR detection techniques. Furthermore, the applicability and mixing capability of tiny reactor systems, termed “microreactors” or “micromixers,” implemented in NMR probes is demonstrated by carbamate- and imine-forming reactions.     

FT‐Raman,FT‐IR spectral and DFT studies on 6, 8‐dichloroflavone and 6, 8‐dibromoflavone

In this study, experimental and theoretical vibrational spectral results of the molecular structures of 6,8‐dichloroflavone (6,8‐dcf) and 6,8‐dibromoflavone (6,8‐dbf) are presented. The FT‐IR and FT‐Raman spectra of the compounds have been recorded together between 4000 and 400 cm⁻¹ and 3500–5 cm⁻¹ regions, respectively. The molecular geometry and vibrational wavenumbers of 6,8‐dcf and 6,8‐dbf in their ground state have been calculated by using DFT/B3LYP functional, with 6‐31 + + G(d,p) basis set used in calculations. All calculations were performed with Gaussian03 software. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. Scale factors have been used in order to compare how the calculated and experimental data are in agreement. Theoretical infrared intensities are also reported. Copyright © 2009 John Wiley & Sons, Ltd.     

Inversion of the X-ray transform from limited angle parallel beam region of interest data with applications to electron tomography

We present a new local tomographic algorithm applicable to electron microscopy tomography. Our algorithm applies to the standard data acquisition method, single-axis tilting, as well as for more arbitrary acquisition methods. Using microlocal analysis we put the reconstructions in a mathematical context, explaining which singularities are stably visible from the limited data given by the data collection protocol in the electron microscope. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ultrasound assisted biobleaching of cotton

In this study, the effect of ultrasound on the activity of the glucose oxidase (GOx) enzyme for bleaching of the cotton fabrics was investigated. Hydrogen peroxide generation with the GOx enzyme from glucose was carried out under ultrasonic homogenizer (UH) and ultrasonic bath support. The aim of using ultrasonic support was to increase the yield of the enzyme reactions. The enzymatically generated hydrogen peroxide was used for bleaching of cotton fabrics. The bleaching process was performed at 90 °C and pH 11 (with NaOH) for 60 min, followed by rinsing at 70 and 50 °C then cold washing. The whiteness degrees of the cotton samples that were bleached by the generated peroxide were compared to the whiteness degrees of the conventionally bleached cotton fabrics. Sufficient whiteness degrees in cotton fabrics could be obtained by enzymatically generated hydrogen peroxide by UH support. The initial whiteness degree of the cotton fabric was 59.9 Stensby degrees; the whiteness was increased to 75.6 Stensby degrees by the GOx enzyme under UH support where the conventional bleaching process yielded a whiteness value of 76.7 Stensby degrees. For efficient cotton bleaching by the GOx enzyme, UH support contributed to the concentration of enzymatically generated hydrogen peroxide by the GOx enzyme. Bleaching of cotton by the GOx enzyme was approved as a more environmentally friendly process compared to the conventional bleaching method in respect of the results of chemical oxygen demand tests.     

Relative flux homomorphism in symplectic geometry

In this work we define a relative version of the flux homomorphism, introduced by Calabi in 1969, for a symplectic manifold. We use it to study (the universal cover of) the group of symplectomorphisms of a symplectic manifold leaving a Lagrangian submanifold invariant. We also show that some quotients of the universal covering of the group of symplectomorphisms are stable under symplectic reduction.

     

Preparation of glutathione loaded nanoemulsions and testing of hepatoprotective activity on THLE-2 cells

To improve bioavailability and stability of hydrophobic and hydrophilic compounds, nanoemulsions are good alternatives as delivery systems because of their nontoxic and nonirritant nature. Glutathione (GSH) suffers from low stability in water, where its encapsulation in nanoemulsions is a powerful strategy to its stability in aqueous systems. The aim of this study was to obtain nanoemulsions from the hydrophobic/hydrophilic contents of N. sativa seed oil so as to improve GSH stability along with bioavailability of N. sativa seed oil. Then, the prepared nanoemulsions were tested for in vitro hepatoprotective activity against ethanol toxicity. To the best of our knowledge, there is no study on the test of nanoemulsions by the combination of Nigella sativa seed oils and GSH in hepatoprotective activity. Here, nanoemulsions with different contents were prepared using Nigella sativa seed oils. Content analyses and characterisation studies of prepared nanoemulsions were carried out. In order to investigate the protective effects against to ethanol exposure, THLE-2 cells were pretreated with nanoemulsions for 2 h with the maximum benign dose (0.5 mg/mL of nanoemulsions). Ethanol (400 mM) was introduced to pretreated cells and nontreated cells for 48- or 72-h periods, followed by cell viability assay was carried out. Fluorescence microscopy tests revealed the introduction of the nanoemulsions into THLE-2 cells. The findings show that nanoformulations have promising in vitro hepatoprotective effects on the THLE-2 cell line against ethanol exposure.     

Design and fabrication of a dual-element off-axis near-eye optical magnifier

The key contribution is the design, analysis, and fabrication of a dual-element off-axis magnifier to improve the state of the art in catadioptric magnifiers. The catadioptric magnifier is composed of a free-form mirror and a lens with a diffractive optical element. A monocular magnifier was prototyped, to our knowledge for the first time, with the specifications of an 8 mm exit pupil, 20 degrees diagonal full field of view, 15 mm eye clearance, 1.5 arcmin resolution, and operating in the photopic visual regime.