Orthocomplemented complete lattices and graphs

The problem I consider originates from Dörfler, who found a construction to assign an Orthocomplemented latticeH(G) to a graphG. By Dörfler it is known that for every finite Orthocomplemented latticeL there exists a graphG such thatH(G)=L. Unfortunately, we can find more than one graphG with this property, i.e., orthocomplemented lattices which belong to different graphs can be isomorphic. I show some conditions under which two graphs have the same orthocomplemented lattice.     

Atome im Doppeltopf-Potential gefangen. Interferenz zwischen zwei Bose-Einstein-Kondensaten

Die Nachricht von den ersten Realisierungen von Bose-Einstein-Kondensaten aus schwach wechselwirkenden Atomen im Sommer 1995 [1,2] (siehe auch Physik in unserer Zeit, 27, 200 (5/1996)) zog eine Welle neuer Forschungsaktivitäten nach sich. Wolfgang Ketterle vom Massachusetts Institute of Technology, MIT, und Kollegen gelang es kürzlich, zwei Bose-Einstein-Kondensate zur Interferenz zu bringen [3].     

Moenomycin a: New chemistry that allows to attach the antibiotic to reporter groups, solid supports, and proteins

Moenomycin A (18) on reaction with the diazonium salt derived from bifunctional (protected) 15 yields the coupling product 19 which on reduction is converted into the moenomycin thiol derivative 21. Thiol 21 has been used to prepare selectively moenomycin dansyl and biotin adducts 26 and 28, respectively. This work was performed with the aim to use moenomycin as a tool for studies of the transglycosylation step in peptidoglycan biosynthesis.     

On a method for estimating the quality of the Fermi approximation

The adequacy of substituting the true neutron-nucleus potential with the Fermi pseudopotential was studied for all elements where elastic neutron scattering is dominant.     

Physico-Chemical Processes Induced by Electrical Breakdown and Discharge Responsible for Memory Effect in Krypton with < 10 ppm Nitrogen

In order to analyze the processes induced by electrical breakdown and discharge responsible for memory effect in krypton-filled tube at low pressure, experimental data mean value of electrical breakdown time delay \(\bar{t}_{d}\) as a function of afterglow period τ (memory curve) was used. Analysis showed that in the 1 μs < τ < 7 ms interval positive ions formed in the previous discharge and in afterglow have a dominant role in secondary emission of electrons from the cathode which lead to initiation of breakdown. In the 7 ms < τ < 30 s interval N(⁴S) atoms have a dominant role in secondary electron emission. These atoms are formed during breakdown and discharge by dissociation of nitrogen molecules that are presented as impurities in krypton. For τ > 30 s the concentration of N(⁴S) atoms decreases significantly so that the dominant role in initiation of breakdown is taken over by cosmic rays and natural radioactivity. The increase in discharge current leads to the decrease in \(\bar{t}_{d}\) in the 1 μs < τ < 7 ms interval due to the increase in positive ion concentration. The increase in applied voltage decreases the values of \(\bar{t}_{d}\) for τ > 7 ms due to the increase in probability for breakdown. It has also been show that exposure of krypton-filled tube to low dose of gamma ray irradiation as well as UV irradiation with wavelength higher than 300 nm leads to the decrease in \(\bar{t}_{d}\). This decrease occurs for τ > 7 ms, when N(⁴S) atoms play a dominant role in breakdown initiation.     

Differences in coating mechanism of structurally different aluminosilicates observed through the thermal analysis

Systematic modification of three structurally different minerals (zeolite, mica, and vermiculite) was carried out with the aim of determining the modification mechanism and exposing the hydrophobic surface that can be used as a sorbent for many organic compounds. Mechanism of modification with cationic surfactant depends strongly on the mineral type. In order to identify the influence of aluminosilicates structural differences on the modification process, adsorption experiments with organic matter and water vapor, supplemented with the DTA/TG analysis, were performed. The cation exchange capacity (CEC) value was 1454?>?560?>?28 meq kg^?1 for zeolite (clinoptilolite), vermiculite, and mica (muscovite), respectively. Despite its CEC value, vermiculite adsorbed three times the amount of organic matter than did clinoptilolite due to the porous structure of zeolite, which acted to limit the adsorption only on the external exchangeable cations. If the loading amount is equal to the CEC or the external cation exchange capacity for clinoptilolite (ECEC?≈?10% CEC), the monolayer will form while mineral surface will have hydrophobic character. Only one active center exists at the surface of the clinoptilolite that was identified by DTA curves with a sharp and defined peak around 300 °C and by the mass loss at the TG diagrams. Two significant and equal active centers were observed in vermiculite, one for the exchange of the surface cations and the other for the interlayer cations and H₂O molecules. Muscovite CEC is negligible, and due to the absence of any other functional groups, the modification of this mineral was impossible.     

Short and long term stability of the elemental composition of human body fluid reference materials and their use as master lots

Summary Studies have been made of both short and long term stability of trace elements in lyophilized human body fluid reference materials, as well as the stability of mercury in reconstituted urine solutions. No detectable concentration changes for mercury, lead and aluminium occurred during the 5-year period. There are large differences in the amounts of mercury loss among different reconstituted materials. Addition of traces of gold to the solutions minimized the mercury loss and increased the useable time of the reconstituted material from hours to 8 days. A certification process based on direct determinations by reference laboratories and by comparison against master lots of the same material and against similar certified reference materials is presented. Values for calcium, copper and mercury obtained from reference laboratories and using the data transfer principle have been assigned in new batches of urine and serum.     

The use of selenophenyl galactopyranosides for the synthesis of α and β-(1→4)-C-disaccharides

Methyl α-C-lactoside {β-D-Gilp-C-(1→4)-α-D-Glcp-OMe} and its α anomer were expeditiously synthesized by radical coupling of various selenophenyl galactopyranosides onto methyl 2,3-di-O-benzyl-4-deoxy-4-C-methylene-α-D-xylo-hexopyranoside, which aretemporarily connected through a silaketal tether.     

Stereochemical differentiation and simultaneous analysis of 3-, 4-, and 5-hydroxyalkanoic acids from biopolyesters by multidimensional gas chromatography

The direct enantioselective analysis of 3-, 4-, and 5-hydroxy fatty acids from biological material has been achieved by enantioselective multidimensional gas chromatography (enantio-MDGC) with heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)- or (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as chiral stationary phase. All the bacteria investigated produced polyesters of enatiomerically pure (R) configured compounds.