Observation of transmission of 45 GHz microwaves through a thin Mo-disk with and without the presence of a magnetic field

Transmission of microwaves of a frequency of 45 GHz through a high-purity, plane-parallel, single-crystalline molybdenum sample of a thickness of 0.15 mm and 0.27 mm, respectively, has been observed, both in the presence of a magnetic field and without a magnetic field. Azbel-Kaner type cyclotron resonance was seen in the signal transmitted through the sample.     

Optical investigations of Mn2+ ion in Cs2CdCl4 and CsCaCl3 single crystals

Summary Polarized absorption, emission and excitation spectra of Cs₂CdCl₄∶Mn²⁺ and emission as well as excitation spectra of CsCaCl₃∶Mn²⁺ single crystals at temperatures down to 77 K are reported. The general features of the spectra are fruitfully analysed within the framework of the strong field scheme of Tanabe and Sugano including Trees' correction. Some finer structure of the crystal field independent levels are observed which are rationalized in terms of vibrational mechanism. A detailed analysis of the spectra indicates octahedral site symmetry around the central metal ion. The authors of this paper have agreed to not receive the proofs for correction.     

Development of a new analytical method for the determination of red beetroot betalains using dispersive solid‐phase extraction

The objective of this study was to develop a method for the determination of red beetroot betalains based on the dispersive solid‐phase extraction and modified QuEChERS methods followed by micro‐high performance liquid chromatography coupled with a mass spectrometer that was equipped with a quadrupole and time‐of‐flight detector. Currently, new techniques for the extraction of the pigments are necessary and in this study, an extraction of beetroot betalains based on the QuEChERS method was developed for the first time. Twelve variants of the methods with different sorbent combinations were tested. The extraction with 15% methanol and with 0.05% formic acid was performed as a reference method to compare the obtained results. In all of the samples with the addition of sorbents, a lower noise was demonstrated in the obtained results. The betalain concentrations obtained using the tested methods were 0.32–0.54 mg g^?1, while the value of the reference method was 0.44 mg g^?1. The method that used the strong ion exchange sorbent (0.44±0.05 mg g^?1) was the most adequate in terms of analyzed content, related standard deviation value and interference compared to the reference method. It was concluded that the properly modified QuEChERS method can be successfully applied for the determination of red beetroot betalains.     

Aqueous polymerization on clay surfaces. III. The polymerization of methyl methacrylate by montmorillonite/thiourea initiating system

Initiation of polymerization of methyl methacrylate with redox system montmorillonite (with lattice Fe³⁺)–thiourea has been achieved. The rates are dependent on both clay mineral and thiourea. Amidosulfenyl radicals are believed to initiate the polymerization on the clay surface. The polymerization produced nonextractable clay–polymer adduct up to an extent of 70 wt %. The pH of the medium (in the acidic range) did not affect the polymerization rate.     

Structure of 6-aminobenzofuran-2-sulfonamide: A tropically active carbonic anhydrase inhibitor

Crystals of the title compound are triclinic. Space groupP1,a=8.652(2),b=5.184(2),c=5.050(2)Å,=100.26(3)°,=100.33(4)°, =72.82(3)°. The structure was solved by direct methods and refined by a full-matrix, least-squares procedure toR=0.033 for 1168 observed [I >2(I)] reflections. The sulfonamide group is at a right angle to the benzofuran ring and the dihedral angle between the benzene and furan ring is 2.0(1)°. In the crystal packing the molecules are linked together by N-HO and N-HN type hydrogen bonds arranging themselves in such a way that there are alternate hydrophobic and hydrophilic regions extended along the a-axis.     

Alkaloids of Michelia lanuginosa wall

Along with the oxoaporphine alkaloid liriodenine, a new oxoaporphine alkaloid lanuginosine and a new noraporphine alkaloid michelanugine have been isolated from the trunk bark of Michelia lanuginosa. They have been shown to possess 1,2-methylenedioxy-9-methoxy-7-oxoaporphine and 1,2-methylenedioxy-9-methoxy-7-hydroxynoraporphine structures through chemical and spectral studies. The stereostructure of michelanugine (6a-H as β and 7-OH as α) has been elaborated with the help of PMR and rotational data.     

On the chemistry of indian orchidaceae plants—II: Dengibsin and dengibsinin,the first natural fluorenone derivatives from dendrobium gibsonii lindl

Dendrobium gibsonii, an Orchidaceae plant yielded the first natural fluorenone derivatives designated dengibsin and dengibsinin to which 1,5-dihydroxy-7-methoxy-9-fluorenone (1) and 1,6-dihydroxy-5, 7-dimethoxy-9-fluorenonc (2) structures have been assigned respectively. The structures are fully supported by the ¹H-NMR, IR, UV and MS spectral data of dengibsin and dengibsnin and a number of their pertinent derivatives. Aurantiamide acetate, dimethyl terephthalate and β-sitosterol have been isolated as the other constituents.