Experimental limits on the production of fractionally charged particles in proton-nucleus and neutrino-nucleus collisions

A search for fractionally chargedQ=1/3 (2/3) particles of different properties of interaction produced in (anti)neutrino-nucleus and in protonnucleus collisions was performed using the scintillator system of the CHARM neutrino detector at the CERN SPS. No events of the cases considered were found. In (anti)neutrino beams production was found to be less than a few times 10^?5 per interaction of a beam particle. In a proton beam an upper limit on the production cross section of ～10^?40 cm² was obtained.     

A facile one‐pot synthesis of tetrahydropyrimidines part 3 Synthesis of [alkanediylbis(3‐alkyl/aralkyl/aryl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)bis(arylmethanones) and [1,4‐phenylenebis(3‐phenyl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)]bis(phenylmethanone)

A facile one‐pot synthetic strategy has been developed for novel [alkanediylbis(3‐alkyl/aralkyl/ aryl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)]bis(arylmethanones) 2a‐c, 2e‐m and [1,4‐phenylenebis(3‐phenyl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)]bis(phenylmethanone) 2d by refluxing enaminones 1a‐f in methanol with diamines and formaldehyde.     

The hydrates and deuterates of ferrous sulfate (FeSO4): a Raman spectroscopic study

A comparative analysis has been carried out on the Raman spectra of FeSO₄·nH₂O (n = 1, 4, 7) including the ²D‐analogs. The effects of changing the degrees of hydration have been found from the lattice, SO₄²⁻ internal, and H₂O internal modes. Increasing degrees of hydration shift the intense ν₁(SO₄) peak to lower wavenumbers and reduce the amount of splitting on the ν₃(SO₄) peaks. Some of the water librational bands cause the broadening of the ν₄(SO₄) peaks in FeSO₄·7H₂O and the ν₂(SO₄) peaks in FeSO₄·7D₂O. The ν₂(H₂O) band in FeSO₄·H₂O is red‐shifted in excess of 100 cm⁻¹ relative to the unperturbed H₂O band. Between 240 and 190 K and between 140 and 90 K in the spectra of FeSO₄.4H₂O, two potential phase transitions have been identified from the changes in the lattice and water‐stretching regions. The resolution of the ν₁(H₂O) and ν₃(H₂O) bands in FeSO₄·4H₂O and FeSO₄·H₂O also improved sharply at low temperatures. The capability of distinguishing various forms of FeSO₄ hydrates unambiguously makes the Raman technique a potential analytical tool for the identification of sulfate minerals on planetary surfaces. Copyright © 2006 John Wiley & Sons, Ltd.     

Expanding the Versatility of Microbial Transglutaminase Using α-Effect Nucleophiles as Noncanonical Substrates

The substrate promiscuity of microbial transglutaminase (mTG) has been exploited in various applications in biotechnology, in particular for the attachment of alkyl amines to glutamine-containing peptides and proteins. Here, we expand the substrate repertoire to include hydrazines, hydrazides, and alkoxyamines, resulting in the formation of isopeptide bonds with varied susceptibilities to hydrolysis or exchange by mTG. Furthermore, we demonstrate that simple unsubstituted hydrazine and dihydrazides can be used to install reactive hydrazide handles onto the side chain of internal glutamine residues. The distinct hydrazide handles can be further coupled with carbonyls, including ortho-carbonylphenylboronic acids, to form site-specific and functional bioconjugates with tunable hydrolytic stability. The extension of the substrate scope of mTG beyond canonical amines thus substantially broadens the versatility of the enzyme, providing a new approach to facilitate novel applications.     

Technical Reports: A Single-photon Counting Pixel Detector for Surface Diffraction Experiments

The intense flux delivered by third-generation synchrotron sources has opened up exciting new possibilities in surface diffraction (SD) studies [1–3]. Nonetheless, practical SD experiments are plagued by several technical problems. Because the crystalline surface is typically probed down to a depth of approximately 1 or 2 nm when using subcritical-angle incident X-ray beams, the scattering volume is only about 10^-12 cm³. This is further exacerbated by the fact that the most interesting information on the surface structure is generally obtained from those regions of diffraction features known as crystal truncation rods (CTRs) where scattering is weakest, i.e., in between Bragg peaks.     

Highly ordered hexatic phases with large spontaneous polarization

In this article the physical properties of hexatic phases of three substances MHPNBC, FOOPP and FNHPP have been studied by differential scanning calorimetry, texture observation and dielectric spectroscopy. Experimental results are discussed from the point of view of existing theories. It is interesting that two of the substances studied, the FOOPP and FNHPP, exhibit enhanced spontaneous polarization in the highly ordered SmI* phase and show a jump of the spontaneous polarization in the vicinity of the SmC*–SmI* transition. In the SmI* phase of FOOPP a very high value of spontaneous polarization of the order of 530?nC?cm^?2 was found. Based on the results obtained the macroscopic and microscopic properties of the hexatic phases are discussed.     

A note on Keldysh's perturbation formalism

The expansion theorem of quantum field theoy relating Heisenberg operators to asymptotic free-field operators is rewritten by means of the time-path technique, originally due to Schwinger, which to date has only found application in statistical mechanics. The theorem is combined with Bogoliubov's initial condition of vanishing correlations in the infinite past to rederive Keldysh's perturbation scheme for non-equilibrium statistical Green's functions.     

Ion equilibria in THF solutions of models of “living” methacrylonitrile oligomers with Li+ counterion

The electro-chemical characteristics of isobutyronitrile lithium (P₁Li) and 2-lithio-4-cyano-2,4-dimethylpentanenitrile (P₂Li) are studied. The dissociation constants K of P₁Li and P₂Li are of the order of 10^?11M and show that in THF mainly contact ion pairs exist. The lower value of K for P²Li is an indication for intramolecular complexation between the counterion and the cyano group, next to the active center. Both compounds tend to form ion triples. The results obtained show that in THF the nitrile group of the second monomer unit participates both in intra- and intermolecular interactions with the counterion.