Application of difference NOE-pumping NMR technique and cold-spray ionization mass spectrometry to identify a ligand binding with a protein receptor.

A difference diffusion-based NMR technique and cold-spray ionization mass spectrometry were employed as a solution-based approach for identifying a ligand binding with a protein receptor. The difference diffusion-based NMR technique, called difference NOE-pumping, can directly detect the ligand interacting with a protein receptor. This technique uses a simple pulse sequence and the diffusion filter can easily be optimized. The cold-spray ionization mass spectrometry (CSI-MS), a variant of electrospray ionization mass spectrometry (ESI-MS) operating at low temperature, has been applied to detect the ligand-receptor complex. The efficiency of these techniques for identifying binding ligands is demonstrated with the human serum albumin (HSA)-drug system.     

Transport properties of ions through temperature-responsive charged membranes prepared using poly(vinyl alcohol)/poly(N-isopropylacrylamide)/poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid)

Temperature-responsive charged membranes were prepared from the polymer mixture of poly(vinyl alcohol) (PVA), in situ polymer of N-isopropylacrylamide (NIPAAm) and PVA, and a polyanion [poly(vinyl alcohol-co-2-acrylamido-2-methylpropane sulfonic acid)]. The membranes were cross-linked under several conditions. The relationship between the preparation conditions and the water content response to temperature change, rH, and the charge density response to temperature change, rCx, was investigated. The membrane cross-linked with glutaraldehyde after annealing has the highest rH and rCx in all the membranes. rCx decreases with increasing polyanion content, and increases with increasing poly(NIPAAm) content. Permeation experiments in a dialysis system consisting of the membrane and mixed KCl and CaCl₂ solutions show that the transport modes of Ca²⁺ ions through the membrane are controlled by temperature changes in two ways: downhill transport (transport along their own concentration gradient in a system) at temperatures below the lower critical solution temperature (LCST) of poly(NIPAAm); uphill transport (transport against their concentration gradient) at temperatures above the LCST.     

THE ROLE OF A PHOTOCHEMICAL REACTION ON THE DEACTIVATION OF EXCITED 4,5',8-TRIMETHYLPSORALEN IN ETHANOL

The transient absorption of an intermediate R which is formed from an excited state higher than the lowest triplet state was observed in an ethanol solution of 4,5′,8-trimethylpsoralen (TMP). The temperature effects on the fluorescence yield φ_F for TMP and on the initial absorbance D_R of R were studied and it was found that D_R increases with increasing temperature whereas φ_F decreases. These results indicate that a photochemical reaction plays an important role on the deactivation of TMP in the excited singlet state     

Microwave spectrum of 3-bromopropene in the excited torsional states

The microwave spectra in the excited states of the CC torsion for the ⁷⁹Br and ⁸¹Br isotopic species of 3-bromopropene were measured in the frequency region 15.3–23.7 GHz. The a-type R-branch and b-type Q-branch rotational transitions in the first and second excited states of one conformer, skew, have been assigned and analyzed. Analysis of the spectrum yields the rotational constants and the nuclear quadrupole coupling constants. From relative intensity measurements the energy differences associated with the CC torsion, between the ground and first excited state, the ground and second excited state have been found to lie 109 and 206 cm^?1, respectively.     

Microwave spectrum of 3-iodopropene

The microwave spectra of 3-iodopropene were measured in the frequency region 12–18 GHz. The a-type R-branch and the b-type Q-branch rotational transitions of one conformer, skew, have been assigned and the rotational constants of the ground state have been obtained: A = 17 644.34, B = 1588.12, and C = 1538.64 MHz. The second-order quadrupole effects give rise to anomalous hyperfine splittings and are analyzed by taking into account χ_ab of the quadrupole coupling tensor. The nuclear quadrupole coupling constants have been determined to be χ_aa = ?1337, χ_bb = 387, χ_cc = 950, and ∥χ_ab∥ = 1081 MHz.     

Kinetic analysis of photopolymerization reaction of lauryl acrylate with a photoinduced chemical reaction calorimeter

Calorimetric studies on kinetics of photopolymerization reactions made previously have been limited by the structures of the calorimeters. This report suggests a thermal-leak type of calorimeter for carrying out kinetic analysis of the photopolymerization reaction. The method was applied to the photopolymerization system consisting of lauryl acrylate and benzoin methyl ether. The results obtained illustrate the utility of this apparatus.     

Vortical Structures in Rotating Uniformly Sheared Turbulence

Rotating homogeneous turbulence with and without mean uniform shear is investigated numerically. It is found that in the shearless case the two-dimensionalization process is most effective when the initial small-scale Rossby number is around unity and the resonant triad interactions play a central role in the process. The vortical structures are studied systematically by changing the relative strength of the mean shear and the system rotation as well as the sense of rotation. (The system is called cyclonic (or anti-cyclonic) when the direction of the vorticity associated with the rotation is the same as (or opposite to) that of the mean shear.) A distinct coherent structure appears in the anti-cyclonic system when the vorticities associated with the rotation and the mean shear cancel out, i.e. the absolute vorticity of the mean shear vanishes. For the linearly most unstable case in the anti-cyclonic system, the vortex tubes develop in the sheared direction, which is caused by instability of vortex layers. For linearly stable cases in both the cyclonic and the anti-cyclonic systems, there appear three typical structures, that is, the oblique vortex tubes, the pancake-like structures and the ribbon-like structures. It is interesting that the flow behaves quite differently between the cyclonic and anti-cyclonic systems even at the same Bradshaw number.