Sensitivity- and Gradient-Enhanced Hetero (ω1) Half-Filtered TOCSY Experiment for Measuring Long-Range Heteronuclear Coupling Constants

An enhanced version of the X(ω₁) half-filtered TOCSY experiment for measurement of long-range heteronuclear coupling constants is proposed which yields high-quality spectra with substantially increased sensitivity and resolution. The modified method features gradient-enhanced X filtering sequences, broadband homonuclear decoupling duringt₁, optional¹J_XHscaling in theF₁domain, and gradient coherence selection in combination with the sensitivity-enhanced protocol for the TOCSY transfer. These modifications extend the applicability of the method—coupling constants can be measured accurately for natural abundance samples at low concentrations and for compounds yielding complex spectra. Computer-aided analysis of E.COSY-type multiplets is applied for the determination of heteronuclear long-range coupling constants.     

Centrifugal spray generator of singlet oxygen for a chemical oxygen-iodine laser

A centrifugal spray generator of singlet oxygen, O₂(¹Δ_g), for driving a chemical oxygen-iodine laser was developed and its operation was experimentally studied. Modeling of the liquid separation from the gas flow showed that the separator designed could remove droplets larger than 0.5 μm from gas, which is very important for the laser operation. This result was confirmed by experiments. Experimental studies proved that O₂(¹Δ_g) could be produced with a high efficiency (chlorine utilization 0.68–0.87 and O₂(¹Δ_g) yield 0.35–0.7) even at very high generator pressures (25–70 kPa), which cannot be attained by other O₂(¹Δ_g) generators.     

Spray generator of singlet oxygen for a chemical oxygen-iodine laser

A spray type of singlet oxygen generator for driving the Chemical Oxygen-Iodine Laser was developed. Singlet oxygen, O₂(¹Δ_g), is generated by a fast reaction of chlorine with basic hydrogen peroxide solution in the form of a dense spray. A mathematical model of this reaction system showed that O₂(¹Δ_g) can be generated in this system with a high yield (0.70–0.80), high utilization of chlorine (0.75–0.95), and effective utilization of liquid (0.36–0.54) at very high generator pressures (35–75 kPa). Experimental studies of this reaction system without an efficient separation of liquid proved an efficient O₂(¹Δ_g) production characterized by a rather high product of chlorine utilization and O₂(¹Δ_g) yield (0.4–0.9) at very high generator pressures (30–80 kPa). This pressure is much higher than the operation pressure used in other generators, which should be beneficial for a pressure recovery system of the COIL. These results provided the basis for designing a centrifugal spray generator with an efficient separation of liquid from the gas flow, which is the subject of the following paper.     

Superspace as a fibre space

Starting from the vector space of anticommuting elements and using the theory of fibre space, the superspace and supersymmetry theory is obtained from a geometrical point of view.     

Line-addressable digital-deflection programmable micromirror array

We report a novel digital-deflection programmable micromirror array driven by micromechanical digital-to-analog converters that eliminates the need for electrical digital-to-analog converters for analog displacement control, thus simplifying the driving circuitry and reducing the overall system cost. Furthermore, owing to the bistable and hysteretic characteristics of parallel-plate electrostatic actuators, an array of micromirrors can be controlled by means of row- and column-addressing lines, which drastically reduce the number of routing wires and allow array sizes to increase while they maintain high array quality.     

Glycopeptides related to beta-endorphin adopt helical amphipathic conformations in the presence of lipid bilayers

A series of glycosylated endorphin analogues designed to penetrate the blood-brain barrier (BBB) have been studied by circular dichroism and by 2D-NMR in the presence of water; TFE/water; SDS micelles; and in the presence of both neutral and anionic bicelles. In water, the glycopeptides showed only nascent helix behavior and random coil conformations. Chemical shift indices and nuclear Overhauser effects (NOE) confirmed helices in the presence of membrane mimics. NOE volumes provided distance constraints for molecular dynamics calculations used to provide detailed backbone conformations. In all cases, the glycopeptides were largely helical in the presence of membrane bilayer models (micelles or bicelles). Plasmon waveguide resonance (PWR) studies showed hen egg phosphatidyl choline (PC) bilayers produce amphipathic helices laying parallel to the membrane surface, with dissociation constants (K(D)) in the low nanomolar to micromolar concentration range. Two low-energy states are suggested for the glycosylated endorphin analogues, a flexible aqueous state and a restricted membrane bound state. Strong interactions between the glycopeptide amphipaths and membranes are crucial for penetration of the BBB via an endocytotic mechanism (transcytosis).     

An investigation of contributions to carbon-13 spin-lattice relaxtion in amino acids and peptide hormones

Carbon-13 spin-lattice relaxation times have been measured in glycine and the tripeptide pro-leu-gly-NH₂. These times are compared with those measured in the same compounds where the glycine α-carbon has been deuterated. In this manner evidence is obtained which indicates that mechanisms other than dipolar interactions with covalently bonded protons may contribute to carbon-13 spin-lattice relaxation. The effect of these additional mechanisms is found to be non-negligible for the carbonyl carbon of glycine and the glycine α-carbon of the tripeptide. The implication of these findings for deducing motional information from carbon-13 relaxation measurements is briefly discussed.