Self-aggregation of reverse bis peptide conjugate derived from the unstructured region of the prion protein

A novel bis scaffold containing a pentapeptide PHGGG, derived from the prion octarepeat, forms fibrils of nanometric dimensions, thus indicating that certain segments in the unstructured region of the prion protein may facilitate an initial fibrillation event.     

Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S)

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.     

Observation of large CP violation in the neutral B meson system

We present a measurement of the standard model CP violation parameter sin2 phi(1) based on a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is fully reconstructed as a J/psi K(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psi K(L), or J/psi K(*0) decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2 phi(1) = 0.99+/-0.14(stat)+/-0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.     

Compressed‐gas‐induced crystallization in tert‐butyl poly(ether ether ketone)

tert‐Butyl‐substituted poly(ether ether ketone) (tBuPEEK), which does not undergo crystallization with thermal annealing, crystallizes readily when treated with compressed CO₂. The dissolved CO₂ causes a reduction in the glass‐transition temperature of the polymer–gas system and enhances the chain mobility of the macromolecules, thereby bringing about crystallization. In the presence of CO₂, crystallization is increasingly favored with increasing CO₂ pressure and treatment temperature. The melting point of tBuPEEK crystals increases linearly with the CO₂ pressure applied in the treatment, indicating an increase in the order and/or size of the crystals. The extent of crystallinity increases when small amounts of methanol or dichloromethane are used as a cosolute with CO₂. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1505–1512, 2001     

The first columnar discotic liquid crystalline anthraquinone metal complexes

In this communication we present the synthesis and characterization of the first two members of a new class of metallomesogen. The Pd and Cu complexes of 1-hydroxy-2,3,5,6,7-pentakis(dodecyloxy)anthra-9,10-quinone were prepared by reacting the respective metal(II) acetate with the ligand. Preliminary mesophase characterization by DSC and polarizing optical microscopy indicates the formation of columnar mesophases in both the complexes.     

Preparation and characterization of 1,2,3‐triazole‐cured polymers from endcapped azides and alkynes

Fourteen commercial polyols have been characterized by GPC, NMR spectroscopy, and elemental analysis. From these, eight corresponding tosylates, six nitrate esters, seven mesylates, 13 alkynes, and 14 azides have been prepared and all these derivatives have been fully characterized. Five alkyne monomers and eight azide monomers were also prepared. Twelve alkynes and 13 azides (functionality 2–4) were combined in 1,3‐dipolar cycloaddition reactions under neat conditions to prepare triazole‐cured polymers, avoiding any heavy metal catalyst. Characterization by NMR spectroscopy, elemental analysis, and gel permeation chromatography indicated triazole polymers 14 , 22 , 23 , 28 , and 30 with degrees of polymerization of 17–28 to be the best candidates for future work. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 238–256, 2008     

Sodium Bisulfite as an Efficient and Inexpensive Catalyst for the One-pot Synthesis of 2,4,5-Triaryl-1<Emphasis Type="Italic">H</Emphasis>-imidazoles from Benzil or Benzoin and Aromatic Aldehydes

Summary. 2,4,5-Triaryl-1H-imidazoles were efficiently synthesized from benzoin or benzil, ammonium acetate, and aromatic or heteroaromatic aldehydes in the presence of sodium bisulfite as catalyst. The present protocol offers significant improvements for the synthesis of 2,4,5-triaryl-1H-imidazoles with regard to yield of products, simplicity in operation, and cheap catalyst.     

Vibrational spectroscopic investigation of poly(p‐phenylene sulfide)

Poly(p‐phenylene sulfide) (PPS) is an important polymer of engineering interest particularly useful in the electronics and automotive industries. Normal mode analysis including phonon dispersion has been performed to understand completely the vibrational spectra of this polymer. Various characteristic features of the dispersion curves have been reported. Crossing/Repulsion between various pairs of modes at certain phase values have been explained as arising due to internal symmetry in the energy momentum space. The heat capacity is calculated as a function of temperature via density‐of‐states in the range 220–360 K. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2353–2367, 2009