Investigation of Parameters that Affect Resin Swelling in Green Solvents

The influence of various physical and chemical factors on the swelling of polystyrene and PEG based resins in greener organic solvents has been systematically investigated. In general, chemical factors: the nature of the functionality/linker and the degree of loading were found to have a far larger influence on the swelling of the resins than physical parameters such as bead size. The results are interpreted in terms of Hansen solubility parameters for the solvents and there is evidence that some solvents interact with the polymeric core of a resin whilst others interact with the functionality. The results are extended to a study of the changes in resin swelling observed during both deprotection and chain elongation reactions during solid phase peptide synthesis.     

d-Space problem and solution set: Relearning to walk after a stroke

A discrete formalism, d-spaces, developed for analyzing complex movements, can be used to construct modes in which a stroke patient may relearn to walk. A specific example is sketched. The analogy between movement dissonance and quantum incompatibility is explored, along with an observationally-based distinction between dissonant and nonfunctional movement.     

Nonperturbative calculation of born-infeld effects on the schrödinger spectrum of the hydrogen atom

We present the first nonperturbative calculations of the nonrelativistic hydrogen spectrum as predicted by first-quantized nonlinear Maxwell-Born-Infeld electrodynamics with point charges. Judged against empirical data our results significantly restrict the range of viable values of the new electromagnetic constant beta introduced by Born. We assess Born's own proposal for the value of beta.     

Structural Studies Reveal Enantiospecific Recognition of a DNA G‐Quadruplex by a Ruthenium Polypyridyl Complex

By using X‐ray crystallography, we show that the complexes Λ/Δ‐[Ru(TAP)₂(11‐CN‐dppz)]²⁺ (TAP=1,4,5,8‐tetraazaphenanthrene, dppz=dipyridophenazine) bind DNA G‐quadruplex in an enantiospecific manner that parallels the specificity of these complexes with duplex DNA. The Λ complex crystallises with the normally parallel stranded d(TAGGGTTA) tetraplex to give the first such antiparallel strand assembly in which syn‐guanosine is adjacent to the complex at the 5′ end of the quadruplex core. SRCD measurements confirm that the same conformational switch occurs in solution. The Δ enantiomer, by contrast, is present in the structure but stacked at the ends of the assembly. In addition, we report the structure of Λ‐[Ru(phen)₂(11‐CN‐dppz)]²⁺ bound to d(TCGGCGCCGA), a duplex‐forming sequence, and use both structural models to provide insight into the motif‐specific luminescence response of the isostructural phen analogue enantiomers.     

An XPS study on the attachment of triethoxsilylbutyraldehyde to two titanium surfaces as a way to bond chitosan

A bioactive coating has the ability to create a strong interface between bone tissue and implant. Chitosan, a biopolymer derived from the exoskeletons of shellfish, exhibits many bioactive properties that make it an ideal material for use as a coating such as antibacterial, biodegradable, non-toxic, and the ability to attract and promote bone cell growth and organized bone formation. A previous study reported on the bonding of chitosan to a titanium surface using a three-step process. In the current study, 86.4% de-acetylated chitosan coatings were bound to implant quality titanium in a two-step process that involved the deposition of triethoxsilylbutyraldehyde (TESBA) in toluene, followed by a reaction between the aldehyde of TESBA with chitosan. The chitosan coatings were examined on two different metal treatments to determine if any major differences in the ability of titanium to bind chitosan could be detected. The surface of the titanium metal and the individual reaction steps were examined using X-ray photoelectron spectroscopy (XPS). Following the deposition of TESBA, significant changes were seen in the amounts of oxygen, silicon, carbon, and titanium present on the titanium surface, which were consistent with the anticipated reaction steps. It was demonstrated that more TESBA was bound to the piranha-treated titanium surface as compared to the passivated titanium surface. The two different silane molecules, aminopropyltriethoxysilane (APTES) and TESBA, did not affect the chemistry of the resultant chitosan films. XPS showed that both the formation of unwanted polysiloxanes and the removal of the reactive terminal groups were prevented by using toluene as the carrier solvent to bond TESBA to the titanium surfaces, instead of an aqueous solvent. Qualitatively, the chitosan films demonstrated improved adhesion after using toluene, as the films remained attached to the titanium surface even when placed under the ultra-high vacuum necessary for XPS, unlike the chitosan films deposited using an aqueous solvent, which were removed when exposed to the ultra-high vacuum environment of XPS.     

Two particle correlations in the central region of pp and π−p interactions at 100–300 GeV/c

Significant positive correlations are seen for all charge combinations of pion pairs with small rapidity separation. Joint rapidity-azimuthal correlations show that this positive correlation occurs when like (unlike) pions are produced with small (large) separation in azimuth.     

Approximate quantum cloning with nuclear magnetic resonance

Here we describe a nuclear magnetic resonance (NMR) experiment that uses a three qubit NMR device to implement the one-to-two approximate quantum cloning network of Buzek et al. [Phys. Rev. A 56, 3446 (1997)]. As expected the experimental results indicate that the network clones all input states with similar fidelities, but as a result of decoherence and incoherent evolution arising from B(1) inhomogeneity the total fidelity achieved does not exceed the measurement bound.     

Synthesis of the new pyrido[1,2-c]benzo-v-triazinium system via valence bond isomerization

α-Pyridylphenyl diazonium salts 2 were found to undergo valence bond isomerization and gave the new pyrido[ 1 ,2-c]benzo-v-triazinium salts 3. The ir and nmr studies on the products showed that isomers 2 and 3 form an equilibrium, and the ring closure is favoured by electron withdrawing substituents.     

Flexible Tuning of Unsaturated β‐Substituents on Zn Porphyrins: A Synthetic,Spectroscopic and Computational Study

A series of zinc porphyrins substituted at adjacent β‐positions with a CN group and para‐substituted ethenyl/ethynyl‐phenyl group have been studied using electronic absorption spectroscopy, resonance Raman spectroscopy and DFT calculations. The oxidative nucleophilic substitution of hydrogen was utilized for the introduction of a cyano substituent on the porphyrin ring. This modification has a remarkable electronic effect on the ring. The resulting porphyrin cyanoaldehyde was further modified in Wittig condensations to give series of arylalkene‐ and arylalkyne‐substituted derivatives. This substitution pattern caused significant redshifting and broadening of the B band, tuning from 433–446 nm. Additionally the Q/B band intensity ratios show much higher values than observed for the parent porphyrin ZnTPP (0.20 vs. 0.03). Careful analysis of the electronic transitions using DFT and resonance Raman spectroscopy reveal that the substituent does not significantly perturb the electronic structure of the porphyrin core, which is still well described by Gouterman’s four‐orbital model. However, the substituents do play a role in elongating the conjugation length and this results in the observed spectral changes.