Synthesis and Anticoagulant Activity of Bioisosteric Sulfonic‐Acid Analogues of the Antithrombin‐Binding Pentasaccharide Domain of Heparin

Two pentasaccharide sulfonic acids that were related to the antithrombin‐binding domain of heparin were prepared, in which two or three primary sulfate esters were replaced by sodium‐sulfonatomethyl moieties. The sulfonic‐acid groups were formed on a monosaccharide level and the obtained carbohydrate sulfonic‐acid esters were found to be excellent donors and acceptors in the glycosylation reactions. Throughout the synthesis, the hydroxy groups to be methylated were masked in the form of acetates and the hydroxy groups to be sulfated were masked with benzyl groups. The disulfonic‐acid analogue was prepared in a [2+3] block synthesis by using a trisaccharide disulfonic acid as an acceptor and a glucuronide disaccharide as a donor. For the synthesis of the pentasaccharide trisulfonic acid, a more‐efficient approach, which involved elongation of the trisaccharide acceptor with a non‐oxidized precursor of the glucuronic acid followed by post‐glycosidation oxidation at the tetrasaccharide level and a subsequent [1+4] coupling reaction, was elaborated. In vitro evaluation of the anticoagulant activity of these new sulfonic‐acid derivatives revealed that the disulfonate analogue inhibited the blood‐coagulation‐proteinase factor Xa with outstanding efficacy; however, the introduction of the third sulfonic‐acid moiety resulted in a notable decrease in the anti‐Xa activity. The difference in the biological activity of the disulfonic‐ and trisulfonic‐acid counterparts could be explained by the different conformation of their L ‐iduronic‐acid residues.     

Highly selective palladium-catalyzed aminocarbonylation and cross-coupling reactions on a cavitand scaffold

Palladium-catalyzed aminocarbonylation and cross-coupling reactions (Suzuki-, Sonogashira-, Stille-coupling) served as highly efficient synthetic tools for the synthesis of novel, functionalized deepened cavitands. Unexpectedly high chemoselectivities towards tetrafunctionalized cavitands have been observed for all of these reactions even using coupling partners much below the stoichiometric amount. No significant formation of either the mono-, di- or trifunctionalized products was observed.     

Poly(allylamine hydrochloride) Functionalized Multiwalled Carbon Nanotube Modified Carbon Paste Electrode as Acetylcholinesterase Biosensor Transducer

In this work, a sensitive, practical and reliable acetylthiocholine (ATCh) biosensor based on poly(allylamine hydrochloride) functionalized multiwalled carbon nanotube (PAH/MWCNT) was fabricated and used for pesticide detection. As far as we know, this is the first work that constitutes the usage of PAH and MWCNT for ATCh biosensor. The developed system was characterized by using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The influence of parameters such as enzyme amount and pH were examined and a linearity between 5×10^?5 M?2.0×10^?3 M for ATCh was obtained. The proposed biosensor was applied for a model pesticide, monocrotophos, detection. The analytical curve showed an excellent linearity in the monocrotophos concentration range of 1–25 pg/mL with an incubation time of 5 min. Limit of detection and limit of quantification values were calculated as 0.88 and 2.9 pg/mL, respectively. The system was also applied for detection of monocrotophos in grape, tomatoe, tap and mineralized water samples and promising recovery values were obtained.     

Universal method for synthesis of artificial gel antibodies by the imprinting approach combined with a unique electrophoresis technique for detection of minute structural differences of proteins, viruses, and cells (bacteria): II. Gel antibodies against virus (Semliki Forest Virus)

Artificial and highly selective antibodies (in the form of gel granules) against proteins can easily be synthesized by a simple, cost-effective imprinting technique [Liao, J.-L. et al., Chromatographia 1996, 42, 259-262]. Using the same method for synthesis of gel antibodies against viruses in combination with analysis by free zone electrophoresis in a rotating narrow bore tube we have shown that artificial gel antibodies against Semliki Forest Virus (wild type) can sense the difference between this virus and a mutant, although they differ in their chemical composition only by three amino acids in one of the three proteins on the surface of the virus particle. The reason for this extremely high resolution is explained by the fact that we use three types of selectivity: (i) shape selectivity (created by the close fit between the antigen and its imprint in the gel), (ii) bond selectivity in the contact area between the antigen and its imprint in the gel antibody, and (iii) charge selectivity, originating from slightly different structures or/and conformations of the antigens.     

Synthesis of sulfonic acid-containing maltose-type keto-oligosaccharides by an iterative approach

Two different series of (2→5)-α-linked homologous keto-oligosaccharides up to tri- and tetrasaccharide were synthesized by an iterative approach, using 3,4,7-tri-O-benzyl-5-O-(2-naphthyl)methyl-1-deoxy-1-ethoxysulfonyl-α-d-gluco-hept-2-ulopyranosyl chloride as a key building block. An iterative cycle consisted of a glycosylation step followed by selective cleavage of the (2-naphthyl)methyl group.     

Measuring Dynamic Pressure in Shock Tube and Musical Instruments with WIKA A-10 Sensor*

International Applied Mechanics - Devices used in scientific research related to musical performance for recording dynamic mechanical processes are described. Recorder LMS SCADAS Mobile, dynamic...     

Hot particles analysis originating from failed and damaged fuels

The increase of activities of fission products and transmutation products in the primary coolant of a nuclear power plant indicates the presence of fuel rod failures. The measurement of the activity concentration of the primary coolant was able to detect fuel failures in the reactor core. Microanalytical methods for examining individual hot particles have been developed and applied to fuel failure detection under normal operation conditions as well as during the severe fuel damage that occurred in the cleaning tank incident at Unit 2 of NPP Paks in April 2003. Several faulty fuel rods can be detected simultaneously by the characterization of individual hot particles originating from the primary water. The analysis of particles originating from the damaged fuels provides information relating to the dissolution process of the fuel debris.     

Characterization of gingerol-related compounds in ginger rhizome (Zingiber officinale Rosc.) by high-performance liquid chromatography/electrospray ionization mass spectrometry

This study sought to determine the utility of liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) coupled with diode array detection in identifying gingerol-related compounds from crude extracts of ginger rhizome. The fragmentation behaviors of compounds in both (-)- and (+)ESI-MS/MS were used to infer and confirm the chemical structures of several groups of compounds, including the gingerols, methylgingerols, gingerol acetates, shogaols, paradols, gingerdiols, mono- and diacetyl gingerdiols, and dehydrogingerdiones. Diode array detection at different wavelengths was used to confirm MS/MS-based identification. In total, 31 gingerol-related compounds were identified from the methanolic crude extracts of fresh ginger rhizome in this study. Three of these compounds were found to be new compounds. This study demonstrated that LC/ESI-MS/MS is a powerful on-line tool for identification of gingerol-related compounds, especially for thermally labile compounds that cannot be readily detected by GC/MS analysis.