Electrostatic interaction between cationic calix[4]pyrroles and anionic porphyrins in water

The formation and characterization of molecular assemblies resulting from mixing of solutions of tetracationic calix[4]pyrroles and tetraanionic porphyrins in water are reported. The self-assembly of the complementary building blocks was quantitatively studied by UV–vis, ¹H NMR, Fluorescence and ESI–MS. Binding constants calculated by absorption spectroscopic titrations were in the range of 10³–10⁵ M^?1. The results indicate that the cationic thiacalix[4]pyrroles show greater binding affinity towards metal free porphyrins than metalloporphyrins under neutral conditions.     

Super Symmetric Partners in <Emphasis Type="Italic">T</Emphasis><Superscript>4</Superscript>-Space

Constructing the operators connecting the state of energy associated with super partner Hamiltonians and super partner potentials for a linear harmonic oscillator has been discussed and it is shown that any super symmetric eigen state of one of the super partner potentials in T ⁴-space is paired in energy with a symmetric eigen state of the other partner potential.     

Mutant tyrosine kinases with unnatural nucleotide specificity retain the structure and phospho-acceptor specificity of the wild-type enzyme

The direct substrates of one protein kinase in a cell can be identified by mutation of the ATP binding pocket to allow an unnatural ATP analog to be accepted exclusively by the engineered kinase. Here, we present structural and functional assessment of peptide specificity of mutant protein kinases with unnatural ATP analogs. The crystal structure (2.8 A resolution) of c-Src (T338G) with N(6)-(benzyl) ADP bound shows that the creation of a unique nucleotide binding pocket does not alter the phospho-acceptor binding site of the kinase. A panel of optimal peptide substrates of defined sequence, as well as a degenerate peptide library, was utilized to assess the phospho-acceptor specificity of the engineered "traceable" kinases. The specificity profiles for the mutant kinases were found to be identical to those of their wild-type counterparts.     

On particle ionization/enrichment of multifunctional nanoprobes: washing/separation-free, acceleration and enrichment of microwave-assisted tryptic digestion of proteins via bare TiO2 nanoparticles in ESI-MS and comparing to MALDI-MS

A simple, rapid, straightforward and washing/separation free of in-solution digestion method for microwave-assisted tryptic digestion of proteins (cytochrome c, lysozyme and myoglobin) using bare TiO(2) nanoparticles (NPs) prepared in aqueous solution to serve as multifunctional nanoprobes in electrospray ionization mass spectrometry (ESI-MS) was demonstrated. The current approach is termed as 'on particle ionization/enrichment (OPIE)' and it can be applied in ESI-MS, atmospheric pressure-matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The bare TiO(2) NPs can assist, accelerate and effectively enhance the digestion efficiency, sequence coverage and detection sensitivity of peptides for the microwave-assisted tryptic digestion of proteins in ESI-MS. The reason is attributed to the fact that proteins or partially digested proteins are easily attracted or concentrated onto the surface of TiO(2) NPs, resulting in higher efficiency of digestion reactions in the microwave experiments. Besides, the TiO(2) NPs could act as a microwave absorber to accelerate and enrich the protein fragments in a short period of time (40-60 s) from the microwave experiments in ESI-MS. Furthermore, the bare TiO(2) NPs prepared in aqueous solution exhibit high adsorption capability toward the protein fragments (peptides); thus, the OPIE approach for detecting the digested protein fragments via ESI and MALDI ionization could be achieved. The current technique is also a washing and separation-free technique for accelerating and enriching microwave-assisted tryptic digestion of proteins in the ESI-MS and MALDI-MS. It exhibits potential to be widely applied to biotechnology and proteome research in the near future.     

Synthesis and evaluation of silica hydride‐based fluorinated stationary phases

Two novel silica hydride‐based fluorinated bonded phases have been synthesized using a hydrosilation procedure to test combined fluorine and hydride selectivity. The bonded moieties were characterized by elemental and spectral analysis. Chromatographic testing was done using hydrophilic analytes in the aqueous normal phase mode. At higher amounts of the nonpolar solvent in the mobile phase, there should be increased retention for solutes such as acids, bases and other polar compounds, whereas nonpolar solutes can be retained when water is increased as in RP chromatography. The synergistic effects of the fluorinated phase selectivity and aqueous normal phase retention on a hydride surface have been explored for small polar molecules. The stability and repeatability of the hydride‐based fluorinated stationary phases were evaluated. The use of acetone as the organic component in the mobile phase was also tested.     

Frequency-modulation-mode-locked optical parametric oscillator

We demonstrate a novel technique for the generation of mode-locked pulses from a continuous-wave (cw) optical parametric oscillator (OPO). The technique is based on the deployment of a phase modulator in combination with an antiresonant ring interferometer internal to a cw OPO, simultaneously providing spectral broadening and phase-to-amplitude feedback modulation. The scheme is implemented in a doubly-resonant cw OPO based on MgO:sPPLT, configured in a standing-wave cavity and pumped at 532 nm. With the phase modulator activated and the cavity length synchronized, a stable train of 800 ps pulses is generated at a repetition rate of 160 MHz. Using single-pass second harmonic generation (SHG) of the OPO output, we observe a four times enhancement in SHG compared with cw operation, confirming the real achievement of energy concentration as a result of mode-locked operation.     

Quaternion-Octonion SU(3) Flavor Symmetry

Starting with the quaternionic formulation of isospin SU(2) group, we have derived the relations for different components of isospin with quark states. Extending this formalism to the case of SU(3) group, we have considered the theory of octonion variables. Accordingly, the octonion splitting of SU(3) group have been reconsidered and various commutation relations for SU(3) group and its shift operators are also derived and verified for different isospin multiplets i.e. I, U and V-spins.     

Octonion Quantum Chromodynamics

Starting with the usual definitions of octonions, an attempt has been made to establish the relations between octonion basis elements and Gell-Mann λ matrices of SU(3) symmetry on comparing the multiplication tables for Gell-Mann λ matrices of SU(3) symmetry and octonion basis elements. Consequently, the quantum chromo dynamics (QCD) has been reformulated and it is shown that the theory of strong interactions could be explained better in terms of non-associative octonion algebra. Further, the octonion automorphism group SU(3) has been suitably handled with split basis of octonion algebra showing that the SU(3) _C gauge theory of colored quarks carries two real gauge fields which are responsible for the existence of two gauge potentials respectively associated with electric charge and magnetic monopole and supports well the idea that the colored quarks are dyons.     

Discrete Symmetries and Generalized Fields of Dyons

We have studied the different symmetric properties of the generalized Maxwell’s–Dirac equation along with their quantum properties. Applying the parity (℘), time reversal ( T\mathcal{T} ), charge conjugation (C\mathcal{C}) and their combined effect like parity time reversal (PT\mathcal{PT}), charge conjugation and parity (CP\mathcal{CP}) and CPT\mathcal{CP}T transformations to various equations of generalized fields of dyons, it is shown that the corresponding dynamical quantities and equations of dyons are invariant under these discrete symmetries.