Energy,exergy, economic and enviro-economic (4E) analysis of gravel coarse aggregate sensible heat storage-assisted single-slope solar still

Journal of Thermal Analysis and Calorimetry - In this work, the energy, exergy, economic and enviro-economic assessments of gravel coarse aggregate sensible heat storage-assisted single-slope solar...     

Reaction of aliphatic imines of trimethylsilylpropinal with 8-mercaptoadenine

N9-Alkyl-7-(trimethylsilyl)-9H-[1,3]-thiazino[3,2-e]purine-4,9-diamines were synthesized by reaction of 3-trimethylsilyl-2-propinal alkylimines with 8-mercaptoadenine in anhydrous DMF. DFT quantum-chemical calculations of isomeric forms of one of the reaction products were performed.     

Long-lived electron capture dissociation product ions experience radical migration via hydrogen abstraction

To explore the mechanism of electron capture dissociation (ECD) of linear peptides, a set of 16-mer peptides were synthesized with deuterium labeled on the alpha-carbon position of four glycines. The ECD spectra of these peptides showed that such peptides exhibit a preference for the radical to migrate to the alpha-carbon position on glycine via hydrogen (or deuterium) abstraction before the final cleavage and generation of the detected product ions. The data show c-type fragment ions, ions corresponding to the radical cation of the c-type fragments, c*, and they also show c*-1 peaks in the deuterated peptides only. The presence of the c*-1 peaks is best explained by radical-mediated scrambling of the deuterium atoms in the long-lived, metastable, radical intermediate complex formed by initial electron capture, followed by dissociation of the complex. These data suggest the presence of at least two mechanisms, one slow, one fast. The abundance of H* and -CO losses from the precursor ion changed upon deuterium labeling indicating the presence of a kinetic isotope effect, which suggests that the values reported here represent an underestimation of radical migration and H/D scrambling in the observed fragments.     

An anomalous Zeeman effect in methane at 3.39 μm

The present paper reports on the first observation of an anomalous Zeeman effect on the hyperfine components of theF ₂ ⁽²⁾ line in methane (λ=3.39 μm), on an asymmetry of a nonlinear resonance in the magnetic field due to the influence of recoid, and on measurements of shifts of individual hyperfine components in weak magnetic fields.     

The Dielectric Anomaly Near the Transition from the Smectic A* to Smectic C* Phase and Visco-Elastic Properties of Ferroelectric Liquid Crystals

A pyro-electric technique is developed which allows the measurement of the dielectric response near the A*-C* phase transition in ferroelectric liquid crystals. The temperature dependence of the elastic modulus K _θ(T) corresponding to the molecular tilt in smectic layers is calculated from the experimental data. Direct pyro-electric measurements of the relaxation time for the spontaneous polarization P _s and the data on K _θ(T) allow us to calculate the temperature behaviour of the twist-viscosity γ₁(T) for the smectic C* phase. The curves γ₁(T) are compared for the smectic C* and the nematic phase of the same compound and the dependence of the twist viscosity on the molecular tilt angle in the C* phase is investigated. The results of the dielectic measurements are discussed in terms of the mean-field approximation.     

Chemical analysis of extra-terrestrial material

The last century has seen enormous developments in methods of determining the composition of celestial bodies. Remote analysis using atomic emission and retrieval of samples for analysis on Earth have been superceded by the in situ application of methods such as γ-ray spectrometry and X-ray fluorescence.     

On the calculation of functions of matrices

The representation of entire functions of matrices via symmetric polynomials of nth order is obtained. A method of deriving analytic formulas for functions of matrices of second, third, and fourth orders is obtained. Symmetric polynomials are used to construct algorithms for the numerical calculations of entire functions of matrices, in particular, of matrix exponentials, not requiring the determination of the eigenvalues of the matrices. The efficiency of the proposed numerical methods is estimated.     

The effect of radical trap moieties on electron capture dissociation spectra of substance P

To further test the hypothesis that electron capture dissociation (ECD) involves long-lived radical intermediates and radical migration occurs within these intermediates before fragmentation, radical trap moieties were attached to peptides with the assumption that they would reduce fragmentation by decreasing the mobility of the radical. Coumarin labels were chosen for the radical traps, and unlabeled, singly-labeled, and doubly-labeled Substance P were analyzed by ECD. The results demonstrated a correlation between the number and position of tags on the peptide and the intensity of side-chain cleavages observed, as well as an inverse correlation between the number of tags on the peptide and the intensity of backbone cleavages. Addition of radical traps to the peptide inhibits backbone cleavages, suggesting that either radical mobility is required for these cleavages, or new noncovalent interactions prevent separation of backbone cleavage fragments. The enhancement of side-chain cleavages and the observation of new side-chain cleavages associated with aromatic groups suggest that the gas-phase conformation of this peptide is substantially distorted from untagged Substance P and involves previously unobserved interactions between the coumarin tags and the phenylalanine residues. Furthermore, the use of a double resonance (DR)-ECD experiment showed that these side-chain losses are all products of long-lived radical intermediate species, which suggests that steric hindrance prevents the coumarin-localized radical from interacting with the backbone while simultaneously increasing the radical rearrangements with the side chains.     

Concerning the shift of nonlinear optical resonances in a magnetic field

The shift of components of the magnetic hyperfine structure (MHS) of a vibrational-rotational molecular transition in a weak magnetic field is explored. The numerical data are given for the methane transition at λ=3.39 μm [theF ₂ ⁽²⁾ component of theP(7) line of thev ₃ band]. The shift of the line contour due to the magnetic field is found when the MHS components overlap.