The classical and relativistic concepts of mass

An elementary presentation is given of classical and relativistic collision dynamics based upon the principle of conservation of momentum. The concepts of mass are shown to be implicitly defined and their basic properties are rigorously derived and discussed. Luxons and tachyons are treated on the same footing as material particles.     

Stereoselective preparation of (RP)-8-hetaryladenosine-3',5'-cyclic phosphorothioic acids

Cyclic adenosine monophosphate (cAMP) has been converted into its 8-bromo derivative and 2'O-TBDMS protected before activation of the phosphoric acid moiety with a reagent generated in situ from oxalyl chloride and DMF. Further reactions with primary amines furnished corresponding phosphoramidates with high stereoselectivity at the phosphorus atom. Cross-coupling reactions with the 8-bromopurine yielded 8-hetaryl derivatives. X-Ray analyses showed the amidates to possess the (S(P))-configuration. Carbon disulfide effected thiylation under strongly basic conditions stereospecifically provided the (R(P))-phosphorothioic acids.     

Ergot alkaloids in Norwegian wild grasses: a mass spectrometric approach

Ergot alkaloids are mycotoxins which are produced among fungi in the family Clavicipitaceae. Poisoning with ergot alkaloids is an important veterinary problem in animal husbandry and has recently also been recognised in wild animals. While the poisoning syndrome observed in domestic animals such as cattle, horses and sheep is usually caused by endophyte-infected grass, the recently observed ergotism among Norwegian cervids is probably due to infection of wild grasses with Claviceps. Mass spectrometry is today the method of choice for the rapid qualitative and quantitative determination of many natural compounds. This study uses tandem quadrupole mass spectrometry as well as ion trap mass spectrometry in connection with electrospray(+) ionisation for the quantification, screening and fragmentation of ergot alkaloids in extracts from Claviceps sclerotia that had been picked from wild grasses from several locations in Norway. Ergotamine, ergovaline, ergonovine and ergocryptine were available as standards and were quantified in the extracts, while ergocrystine, ergocornine, ergonine/ergosine, lysergic acid and lysergol were identified on the basis of their molecular weights and semi-quantified. Ergocrystine dominated the alkaloid spectrum of most extracts. Levels of the quantified alkaloids were in the range 0.2-9300 microg/g. Several unknown ergot alkaloids were found in the extracts. MS(n) experiments identified some as simple lysergic acid amide derivatives, while othes are probably related to ergocrystine and ergocryptine by dehydration, dehydrogenation and/or amino acid substitution at R(1) of the peptide moiety.     

Nanowires for surface enlargement of narrow-bore fused-silica tubing

A method for preparation of silica nanowires with dimensions of d = 10-100 nm, l = 5-500 nm, is described. The nanostructured material is an integral part of the inner surface of narrow bore fused-silica capillary tubing. The wire preparation method is based on a decomposition of 2-chloro-1,1,2-trifluoroethyl methyl ether at elevated temperature and pressure. The silica bulk material is rearranged via a sustained silica-hydrogen fluoride chemistry, and reaction mechanisms for this process are proposed. The method is suitable for preparing long lengths of tubing with the modified surface. It is our belief that the texture of the capillary wall with its increased surface area is useful for applications such as microreactions, catalysis, and high-resolution pressure and/or electrodriven open-tubular liquid chromatography.     

Development of a high-performance liquid chromatography carbon column based method for the fractionation of dioxin-like polychlorinated biphenyls

A method to separate polychlorinated biphenyls (PCBs) by using high-performance liquid chromatography (HPLC) was developed. The HPLC column was packed with Amoco PX-21 activated carbon dispersed on octadecylsilane (ODS). The separation was carried out by gradient elution with n-hexane-dichloromethane and toluene in the forward direction followed by reversed elution with toluene. The results show that this HPLC method is useful for the separation of PCBs according to the number of substituted ortho chlorine atoms attached to the biphenyl structure. Average recoveries for a number of individual di-ortho PCBs, mono-ortho PCBs, and non-ortho PCBs in three selected elution windows were 97, 92, and 96%, respectively. Clophen A50, a herring sample, and a cod liver oil sample were fractionated on the column and the analytical results are compared with data from the literature. The method presented here is useful for quantitative separations of mono-ortho PCBs as well as non-ortho PCBs which have been assigned toxic equivalency factors by the World Health Organisation.     

Determination of paramethoxyamphetamine and other amphetamine-related designer drugs by liquid chromatography/sonic spray ionization mass spectrometry

Paramethoxyamphetamine (PMA) is an amphetamine-like designer drug that has emerged recently on the European illicit drug market. This drug has a wicked reputation, as a number of lethal intoxications have occurred. A method using high-performance liquid chromatography coupled to ion trap based mass spectrometry (LC/MS) is described for the determination of this compound together with 3,4-methylenedioxymethamphetamine (XTC or MDMA), amphetamine and 3,4-methylenedioxyamphetamine (MDA) in human matrices. A liquid/liquid extraction (LLE) was applied to whole blood, urine and postmortem tissues. Reversed-phase liquid chromatography was performed on a narrow-bore phenyl-type column at a flow rate of 0.3 mL/min. A switch box allowed disposal of early-eluting irrelevant material to waste, protecting the mass spectrometer from contamination. The column effluent was directed into an ion trap mass spectrometer by a sonic spray ionization (SSI) interface. The method was validated for all three matrices, proving the applicability of SSI even when dealing with complex biological matrices. The within-and between-day precisions were less than 17.5% and accuracy was below 16.2%. Weighted (1/x) quadratic calibration curves were generated ranging from 10 to 1000 ng/mL (blood and urine) or 20 to 2000 ng/g (tissue) and correlation coefficients (r(2)) always exceeded 0.995. In addition, the mass spectrum of PMA is given together with a proposed fragmentation pattern for the obtained LC/MS spectrum. This information can be useful for future identification of PMA with LC/MS in biological matrices as well as in confiscated powders or tablets.     

False targets efficiency in defense strategy

The paper analyzes the efficiency of deploying false targets as part of a defense strategy. It is assumed that the defender has a single object that can be destroyed by the attacker. The defender distributes its resource between deploying false targets and protecting the object from outside attacks. The attacker cannot distinguish the false targets from the defended object (genuine target). Therefore the attacker has no preferences for attacking one target rather than another target. The defender decides how many false targets to deploy whereas the attacker decides how many targets to attack. The article assumes that both the defender and attacker have complete information and full rationality. The optimal number of false targets and the attacked targets are obtained for the case of fixed and variable resources of the defender and the attacker as solutions of a non-cooperative game between the two agents.     

Endogenizing the sticks and carrots: modeling possible perverse effects of counterterrorism measures

We present a novel model capable of distinguishing between the effects of negative incentives (“sticks”) and positive incentives (“carrots”) for influencing the behavior of intelligent and adaptable adversaries. Utilities are developed for the defender and the terrorist. The defender is assumed to have a unit cost of defense, and unit costs of providing negative and positive incentives. The terrorist likewise has a unit cost of attack, which may either increase or decrease if the defender provides negative incentives, and enjoys a unit benefit of positive incentives. We show that the potential for perverse effects of counterterrorism (e.g., the emergence of hatred) can cause defenders to rely on positive incentives and decrease their reliance on negative incentives at equilibrium, with use of negative incentives completely eliminated in situations where these would be moderately effective when applied. With low potential for perverse effects of counterterrorism, the defender should rely on effective negative incentives.     

Nanometre resolution using high-resolution scanning electron microscopy corroborated by atomic force microscopy

The resolving power of high-resolution scanning electron microscopy was judged using topographical height data from atomic force microscopy in order to assess the technique as a tool for understanding nanoporous crystal growth.     

Biochemical and biomedical application of monodisperse polymer particles

Macroporous particles with large pores are used for size exclusion chromatography of carbohydrates with very high molecular weights. Macroporous particles of different sizes are used for multiple immunofluorometric analysis by flow cytometry. Porous magnetic particles with protein A coupled to the surface of the pores combine a high capacity in binding of IgG with easy handling of the particles. Magnetic beads with boronic acid coupled to the surface are applied for selective isolation of subclasses of cells. The beads are detached from the cells by addition of sorbitol, leaving free, pure cell fractions in good yield. The use of magnetic particles in molecular biology is described.