Search results for "cyclic"

Bioaccumulation of hepatotoxins : A considerable risk in the Latvian environment

2014

Abstract The Gulf of Riga, river Daugava and several interconnected lakes around the City of Riga, Latvia, form a dynamic brackish-freshwater system favouring occurrence of toxic cyanobacteria. We examined bioaccumulation of microcystins and nodularin-R in aquatic organisms in Latvian lakes, the Gulf of Riga and west coast of open Baltic Sea in 2002–2007. The freshwater unionids accumulated toxins efficiently, followed by snails. In contrast, Dreissena polymorpha and most lake fishes (except roach) accumulated much less hepatotoxins. Significant nodularin-R concentrations were detected also in marine clams and flounders. No transfer of nodularin-R and microcystins between lake and brackish …

Effect ofMicrocystis aeruginosa andNodularia spumigena on survival ofEurytemora affinis and the embryonic and larval development of the Baltic herrin…

2003

Laboratory experiments were carried out to investigate the effect of two strains of Microcystis aeruginosa and a strain of Nodularia spumigena on the survival of Eurytemora affinis (Copepoda) and on the embryonic and larval development of the Baltic spring-spawning herring Clupea harengus membras. The trials were made in water taken from Parnu Bay, at a salinity of 3.7–5.1 psu, a constant temperature (15°C ± 1°C in trials with Eurytemora and herring embryos; 18°C ± 2°C with herring larvae), and an oxygen concentration of 8.8–10.4 ppm. The strains tested had a negative impact on the survival of Eurytemora, as well as on the embryonic development and hatching regime of the Baltic herring. In …

Solid-State Synthesis of “Bamboo-Like” and Straight Carbon Nanotubes by Thermolysis of Hexa-peri-hexabenzocoronene–Cobalt Complexes

2006

On-surface Synthesis of a Chiral Graphene Nanoribbon with Mixed Edge Structure.

2020

Abstract Chiral graphene nanoribbons represent an important class of graphene nanomaterials with varying combinations of armchair and zigzag edges conferring them unique structure‐dependent electronic properties. Here, we describe the on‐surface synthesis of an unprecedented cove‐edge chiral GNR with a benzo‐fused backbone on a Au(111) surface using 2,6‐dibromo‐1,5‐diphenylnaphthalene as precursor. The initial precursor self‐assembly and the formation of the chiral GNRs upon annealing are revealed, along with a relatively small electronic bandgap of approximately 1.6 eV, by scanning tunnelling microscopy and spectroscopy.

Multiply Transitive Permutation Groups

1982

Since the beginnings of finite group theory, the multiply transitive permutation groups have exercised a certain fascination. This is mainly due to the fact that apart from the symmetric and alternating groups not many of them were known. Only very recently final results about multiply transitive permutation groups have been proved, using the classification of all finite simple groups (see 7.5).

On finite products of totally permutable groups

1996

In this paper the structure of finite groups which are the product of two totally permutable subgroups is studied. In fact we can obtain the -residual, where is a formation, -projectors and -normalisers, where is a saturated formation, of the group from the corresponding subgroups of the factor subgroups.

Studies of the binding of diolepoxide metabolites of polycyclic aromatic hydrocarbons to DNA using electrofluorescence polarization spectroscopy

1996

In the electrofluorescence method, a solution of DNA with covalently bound polycyclic hydrocarbons is placed in an electric field, and changes in the intensity of polarized fluorescence are observed. Under the correct conditions, these charges can be used to determine a value for the angle psi between the long axis of the hydrocarbon molecule and the axis of the DNA helix. For DNA or poly(dA-dT) treated with each stereoisomer of anti-benzo[c]phenanthrene diolepoxide, psi ranged from 55 degrees to 61 degrees, consistent with a mixture of quasi-intercalated adenine adducts and externally bound guanine adducts. Similar results were obtained with another set of 'fjord-region' diolepoxides, deri…

Stiffness and strength of composite truss beam to R.C. column connection in MRFs

2015

Abstract The results of experimental and numerical investigations on the cyclic behavior of composite truss beam to reinforced concrete column connection of moment resisting frames are reported. The beams are constituted by a steel truss and end zone added rebar embedded within a concrete block cast in place, so that, after curing, the steel truss and the added rebar work together with the concrete matrix as reinforcement of the composite beam. Particularly, three specimens of two-span continuous beams were tested under monotonic and cyclic actions as three point bending test. With the goal to investigate about the behavior of the end zone of the beam integrated into a moment resisting fram…

Synthesis and characterisation of N-glycosyl amines from the reaction between 4,6-O-benzylidene-D-glucopyranose and substituted aromatic amines and a…

2001

Twelve N-glycosyl amines were synthesised using 4,6-O–benzylidene-D-glucopyranose and different substituted aromatic amines, including some diamines that resulted in bis-glycosyl amines. Another set of six N–glycosyl amines was synthesised using different hexoses and pentoses and 2–(o–aminophenyl)benzimidazole. All compounds were isolated as solid products and purified, their elemental compositions were established, and these were characterised by NMR (1H and 13C), UV–Vis, and FTIR spectroscopy, by FAB mass spectrometry (molecular-ion peaks gave molecular weights), and by their optical rotations. While the protected saccharide, 4,6-O-benzylidene-D-glucopyranose, exists as a mixture of β and…

Heterocyclic photorearrangements. Photochemical behaviour of some 3,5-disubstituted 1,2,4-oxadiazoles in methanol at 254 nm

1988

Photochemical behaviour of some 3,5-disubstituted 1,2,4-oxadiazoles in methanol at 254 nm has been investigated. Ring photoisomerization to the 1,3,4-oxadiazole heterocycle or formation of open chain compounds involving the nucleophilic solvent was shown to depend on the nature and the position of the substituent. Photoinduced ring closure into the benzimidazole system, involving a 3-N-phenylamino side chain sequence and a photolytic intermediate of the oxadiazole heterocycle, is also reported.