Nondynamical calculation of polarization observables in d + d reactions at low energies

The parametrization of cross-section, analysing power and spin-correlation observables in terms of (l, s, J) matrix elements is given for reactions²H(d, p)³H and²H(d, n)³He at low energies. It is shown that a nearly complete set of matrix elements can be obtained from these observables. The feasibility of colliding-beam arrangement for the spin-correlation experiment is estimated.     

Nuclear reactions of medium and heavy target nuclei with high-energy projectiles

Nuclear reactions induced by 3·65 A GeV¹²C-ions and 3·65 GeV protons on target elements⁵⁵Mn,⁵⁹Co,^nat Ni and^natCu were investigated by using the foil stack activation technique and Ge(Li) gamma-ray spectroscopy. Charge dispersions and mass-yield distributions of radioactive residues were obtained from the parametrization of measured spallation cross sections. Discussion of results from this and other radiochemical reactions of high-energy protons and¹²C-ions with complex nuclei is presented in terms of the concepts of limiting fragmentation and factorization.     

Application of BaF2 scintillator to off-line gamma-ray spectroscopy

Total cross sections of the monitoring reaction²⁷Al(d, 3p 2n)²⁴Na at 3·0 AGeV and 3·65 AGeV were determined from direct gamma-ray counting of irradiated targets with a spectrometer using a large volume BaF₂ scintillation crystal. Cross sections of 14·1 ± 1·3 mb and 14·7 ±± 1·2 mb are compared with previous data at other energies.     

Nuclear reactions of medium and heavy target nuclei with high-energy particles IV. Interpretation of mass fragment yields

Target residue mass distributions in 3·65 A GeV¹²C-ion- and 3·65 GeV proton-induced reactions on medium and heavy target nuclei have been interpreted in the theoretical framework of the intranuclear cascade and abrasion-ablation models. While the intranuclear cascade model gives a good approximation to experimental yields of residues produced in both types of interaction, the abrasion-ablation model was found to overestimate mass-yield distributions in the vicinity of the target mass numbers.     

Thermoanalytical Study of O,O'-dibenzoyl-(2R, 3R)-Tartaric Acid SMC

A non-isothermal experimental study using thermogravimetry (TG) and differential scanning calorimetry (DSC) was conducted for investigation the oxidation reactivity of natural phosphate and its demineralised products. The analyses were carried out in oxygen atmosphere and at different heating rate (5, 10, 20, 30, 50, 60°C min^-1) up to 1000°C. The results indicated that the material washed with HCl from the original phosphate, mainly apatite and carbonates of calcium and magnesium, as well as with HCl/HF, silicates minreals, had an inhibition effect during oxidation reactions of organic material. The increase of the heating rate shifted the reactions to higher temperatures. In addition, kinetic parameters were determined by assuming a single first-order kinetic model, using the Coats-Redfern method. The influences of demineralization process of natural phosphate and the heating rate were examined and discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermoanalytical Study of O,O'-Dibenzoyl-(2r,3r)-tartaric Acid; Part III. SMC-s formation with chiral secondary alcohols

The enantioselectivity of the diastereomeric supramolecular compound (SMC) formation between O,O'-dibenzoyl-(2R,3R)-tartaric acid (DBTA) and chiral secondary alcohols was investigated. On the basis of TG measurements the DBTA:chiral alcohol molar ratio in the SMC-s is nearly 1:1. Among the investigated complexes the most stable SMC is trans-2-iodo-cyclohexanol-DBTA. The SMC forming capability and the enantioselectivity depends on the space filling of the alcohol side chain or ring. In the case of trans-2-halogen-cyclohexanols a relationship can be observed between the thermal stability of the SMC-s and the enantioselectivity of SMC forming. This revised version was published online in August 2006 with corrections to the Cover Date.     

Novel functional monomer for the electrochemical synthesis of highly affine epitope-imprinted polymers

To address the lack of functional monomer diversity for the electrosynthesis of protein-selective molecularly imprinted polymers (MIPs), we introduce a new concept able to lead to a new class of functional monomers. This is based on conjugating an electropolymerizable monomer unit (umbelliferone) to an amino acid for closer mimicking of protein-based natural affinity ligands such as antibodies. As the first representative of this class of monomers an aspartate-umbelliferone (Asp-UMB) conjugate was synthesized and here we provide the proof for its suitability to generate highly affine MIPs for proteins by epitope imprinting. As model we used a heptapeptide (GFNCYFP) stemming from the receptor binding domain (RBD) of the SARS-CoV-2 spike protein to generate epitope-imprinted polymers able to recognize the parent RBD protein. For rapid optimization and assessment of the binding kinetics we prepared MIP microarrays on surface plasmon resonance imaging (SPRi) chips. First the peptides were microspotted on the bare gold surface of the chips followed by the electropolymerization of Asp-UMB. This resulted in ca. 2 nm thick, highly uniform, and electrically insulating polymer film, well suited both for hierarchical epitope imprinting and SPRi read-out. Taking advantage also of the on-chip optimization enabled by the microarray format the increased functional diversity of the new monomer resulted in highly affine MIPs with equilibrium dissociation constants in the lower picomolar range.     

Mechanism of Optical Resolutions Via Diastereoisomeric Salt Formation. Part 6 Thermoanalytical investigation of the optical resolution of racemic mandelic acid with S-(+)-2-benzylamino-butanol

The optical resolution of racemic mandelic acid (I) by S-2-benzylamino-butanol (II) was performed in water, ethyl acetate, and water saturated ethyl acetate. It was found that the efficiency of the resolution is three times higher in water saturated ethyl acetate than in either water or ethyl acetate. The salt mixtures produced during the resolutions and the pure diastereoisomeric salts were analyzed by TG, DSC and X-ray powder diffraction measurements. The R-(-)-I×S-(+)-II salt has the higher melting point and heat of fusion value which indicates that this is the more stable salt. Though the general assumption is that diastereoisomeric salt pairs of successful optical resolutions form eutectic systems, the R-mandelic acid-S-2-benzylamino-butanol and the S-mandelic acid-S-2-benzylamino-butanol system was found to behave in a different way. Melting did not start at or near the estimated eutectic temperature. The difference can be explained either by miscibility in the solid phase (solid solution) or by a blocked interaction between the crystals of the two solid salts. This unusual behaviour of the salt pair should be responsible for the unusual difference in the efficiency of the resolutions performed in different solvents This revised version was published online in August 2006 with corrections to the Cover Date.     

Modeling scale-free neurodynamics using neuropercolation approach

Critical properties of dynamical models of neural populations are studied. Based on the classical work of Renyi-Erdos on the evolution of random graphs, a new class of random cellular automata models called neuropercolation has been introduced. We show the emergence of phase transitions in neuropercolation models at critical combination of several control parameters, including the level of external gain and noise, the density of long-range axonal connections (small-world phenomenon), and the sparseness of feedback between excitatory and inhibitory neural populations. Noise level and structural properties of the cortical tissue has been used to control the critical exponent, starting from white noise (slope 0) far away from criticality. The results show that scale-free power spectral density characterizes the dynamics near criticality, where exponent with a power exponent approaching –2. The results are interpreted in the context of recent experimental findings on the dynamics and structure of the cortex. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)