Construction of Nonlinear Stabilizer for Trajectories of Economic Growth

A dynamic model of optimization of R&D intensity is studied for analyzing the effect of the spillover technology assimilation on techno-economic growth. The research focuses on the issue of a reasonable balance in the R&D investment policy between the indigenous technology stock and exogenous technology flow. On the basis of the concavity properties of the Hamiltonian, a nonlinear stabilizer sustaining proportional techno-economic growth is constructed. Trends of optimal R&D intensity are examined depending on the values of the model macroeconomic parameters and the feedback variables. Econometric analysis shows that additional investments and restructuring of these sources for knowledge absorption could have the effect of increasing returns and provide a strong leverage for reaching qualitatively higher levels of sales, technology development, and consumption index. The research was sponsored by the SIMOT Program of the Japanese Ministry of Education, Science and Technology. A.M. Tarasyev was supported by the Russian Fund for Basic Research, Grants 05-01-00601, 05-01-08034, Russian Fund for Humanities, Grant RFH 05-02-02118a, and by the Program for the Sponsorship of Leading Scientific Schools, Grant NSCH-791.2003.1.     

Assisted intramolecular proton transfer in (uracil)2Ca2+ complexes

The structure and relative stability of the complexes between uracil dimers and Ca²⁺, as well as the proton transfer (PT) processes within these dimers, have been investigated by the density functional theory methods. Although in uracil dimers PT occurs as an almost synchronous double PT processes that connect the diketo dimer with a keto-enol dimer, the process within the most stable (uracil)₂Ca²⁺ complexes is much more complicated, and the product of the reaction looks like the result of an intramolecular PT from one of the NH groups of one monomer to one of the carbonyl groups of the same monomer. An analysis of the force profile along the reaction coordinate shows that the intimate mechanism implies three elementary steps, two intermolecular PTs, and an in-plane displacement of one monomer with respect to the other. The result of this so-called assisted intramolecular proton transfer is the formation of a dimer in which only one monomer is a keto-enol derivative, the other monomer being apparently unchanged, although it suffers significant structural rearrangements along the reaction coordinate. Quite importantly, this dimer is significantly stabilized upon Ca²⁺ association; therefore, while the most stable uracil dimers correspond systematically to associations involving only the diketo forms, in (uracil)₂Ca²⁺ complexes the most stable structures correspond to those in which one of the monomers is a keto-enol uracil isomer.     

Application of association models to mixtures containing alkanolamines

Two association models, the CPA and sPC-SAFT equations of state, are applied to binary mixtures containing alkanolamines and hydrocarbons or water. CPA is applied to mixtures of MEA and DEA, while sPC-SAFT is applied to MEA-n-heptane liquid-liquid equilibria and MEA-water vapor-liquid equilibria. The role of association schemes is investigated in connection with CPA, while for sPC-SAFT emphasis is given on the role of different types of data in the determination of pure compound parameters suitable for mixture calculations. Moreover, the performance of CPA and sPC-SAFT for MEA-containing systems is compared. The investigation showed that vapor pressures and liquid densities were not sufficient for obtaining reliable parameters with either CPA or sPC-SAFT, but that at least one other type of information is needed. LLE data for a binary mixture of the associating component with an inert compound is very useful in the estimation. The simple 4-site scheme is suitable for both CPA and sPC-SAFT and little is gained by using more complex association schemes. Finally, the results of CPA and sPC-SAFT are overall similar and whatever differences are seen appear to be more related to details in the parametrization rather than the different functional forms of the two equations of state.     

Stability and iron coordination in DNA adducts of Anthracycline based anti-cancer drugs

There is evidence that the interaction of the α-ketol group of the Doxorubicin and Epirubicin anti-cancer drugs with Fe(iii) generates hydroxyl radicals under aerobic conditions, causing cardiotoxicity in patients. Considering that the formation of DNA adducts is one of the main targets of Anthracycline drugs, we have in the present study characterized several [Anthracycline-DNA]Fe(iii) complexes with respect to their stability and Fe(iii) coordination, by means of MD simulations. Iron is found to coordinate well to the drugs containing an α-ketol group, this being the only group of the drug that binds to the metal. The complexes containing an α-ketol group, [Doxorubicin-DNA]Fe(iii) and [Epirubicin-DNA]Fe(iii), thus show greater stability than those not containing it, i.e., [Daunorubicin-DNA]Fe(iii), [Idarubicin-DNA]Fe(iii) and [5-Imino-Daunorubicin]Fe(iii). Metal attachment to the α-ketol group is furthermore facilitated by the phosphate groups of DNA. The coordination to iron in the [Doxorubicin-DNA]Fe(iii) system is smaller than that found for the [Epirubicin-DNA]Fe(iii) system, and the corresponding number of coordinating waters in the former is larger than in the latter. This may in turn result in higher hydroxyl radical production, thus explaining the increased cardiotoxicity noted for Doxorubicin.     

Isobaric heating of polystyrene and evaluation of the Narayanaswamy parameter x from volume recovery data

Structure parameter x, defining the relative contributions of temperature and structure to the relaxation times, which is applied in Tool-Narayanaswamy-Moynihan (TNM) equation, was evaluated from volume heating isobars for polystyrene (PS) applying the peak shift method. The peak shifted with changing structural state of PS prior heating, which was reached by different period of aging time at 89 °C < T_g up to 2544 h. In this novelized procedure for volume data, originally tested only for enthalpic measurements, high sensitivity of peak temperature (position of inflection point of the heating isobar) was shown, together with high linearity of data. This allows to directly and sensitively calculate the shift and consequently structure parameter x. The value found in the research, x = 0.40 ± 0.02, is in good agreement with published results obtained by the peak-shift method from enthalpy data of PS.     

Influence of particle concentration on the electrorheological efficiency of polyaniline suspensions

The dependence of the efficiency of positive electrorheological (ER) phenomenon, expressed as a ratio of the low-shear electroviscosity to the field-off viscosity, on the particle concentration of polyaniline base suspensions in silicone oil has been studied. A simple analysis reveals that the dependence of the efficiency on the volume fraction of suspended particles may have a maximum at which the optimum ER performance of material is expected. Experimental results confirmed this expectation. It is demonstrated that with higher temperature the maximum is shifted to higher particle concentration.     

Synthesis of dopamine and serotonin derivatives for immobilization on a solid support

The two important neurotransmitters dopamine and serotonin are synthesized with short PEG tethers and immobilized on a magnetic solid support. The tether is attached to the aromatic moiety of the neurotransmitters to conserve their original functional groups. This approach causes minimal alteration of the original structure with the aim of optimizing the immobilized neurotransmitters for aptamer selection by SELEX. For the dopamine derivative, the tether is attached to the aromatic core of a dopamine precursor by the Sonogashira reaction. For serotonin, a link to the indole core is introduced by a Claisen rearrangement from the allylated phenol moiety of serotonin. The tethers are azide-functionalized, which enables coupling to alkyne-modified magnetic beads. The coupling to the magnetic beads is quantified by UV spectroscopy using Fmoc-monitoring of the immobilized dopamine and serotonin derivatives.     

Modelling peptide-metal dication interactions: formamide-Ca(2+) reactions in the gas phase

The collision induced dissociation of formamide-Ca(2+) complexes produced in the gas phase through nanoelectrospray ionization yields as main products ions [CaOH](+), [HCNH](+), [Ca(NH(2))](+), HCO(+) and [Ca(NH(3))](2+) and possibly [Ca(H(2)O)](2+) and [C,O,Ca](2+), the latter being rather minor. The mechanisms behind these fragmentation processes have been established by analyzing the topology of the potential energy surface by means of B3LYP calculations carried out with a core-correlated cc-pWCVTZ basis set. The Ca(2+) complexes formed by formamide itself and formimidic acid play a fundamental role. The former undergoes a charge separation reaction yielding [Ca(NH(2))](+) + HCO(+), and the latter undergoes the most favorable Coulomb explosion yielding [Ca-OH](+) + [HCNH](+) and is the origin of a multistep mechanism which accounts for the observed loss of water and HCN. Conversely, the other isomer of formamide, amino(hydroxyl)carbene, does not play any significant role in the unimolecular reactivity of the doubly charged molecular cation.     

Photophysics, Photochemistry and Energetics of UV Light Induced Disulphide Bridge Disruption in apo-α-Lactalbumin

Continuous 295 nm excitation of whey protein bovine apo-α-lactalbumin (apo-bLA) results in an increase of tryptophan fluorescence emission intensity, in a progressive red-shift of tryptophan fluorescence emission, and breakage of disulphide bridges (SS), yielding free thiol groups. The increase in fluorescence emission intensity upon continuous UV-excitation is correlated with the increase in concentration of free thiol groups in apo-bLA. UV-excitation and consequent SS breakage induce conformational changes on apo-bLA molecules, which after prolonged illumination display molten globule spectral features. The rate of tryptophan fluorescence emission intensity increase at 340 nm with excitation time increases with temperature in the interval 9.3–29.9°C. The temperature-dependent 340 nm emission kinetic traces were fitted by a 1st order reaction model. Native apo-bLA molecules with intact SS bonds and low tryptophan emission intensity are gradually converted upon excitation into apo-bLA molecules with disrupted SS, molten-globule-like conformation, high tryptophan emission intensity and red-shifted tryptophan emission. Experimental Ahrrenius activation energy was 21.8 ± 2.3 kJ.mol⁻¹. Data suggests that tryptophan photoionization from the S₁ state is the likely pathway leading to photolysis of SS in apo-bLA. Photoionization mechanism(s) of tryptophan in proteins and in solution and the activation energy of tryptophan photoionization from S₁ leading to SS disruption in proteins are discussed. The observations present in this paper raise concern regarding UV-light pasteurization of milk products. Though UV-light pasteurization is a faster and cheaper method than traditional thermal denaturation, it may also lead to loss of structure and functionality of milk proteins.     

Identification, cloning and characterization of a novel 47 kDa murine PKA C subunit homologous to human and bovine Cβ2

Background  

SCF ubiquitin ligases target numerous proteins for ubiquitin dependent proteolysis, including p27 and cyclin E. SCF and other cullin-RING ligases (CRLs) are regulated by the ubiquitin-like protein Nedd8 that covalently modifies the cullin subunit. The removal of Nedd8 is catalyzed by the Jab1/MPN domain metalloenzyme (JAMM) motif within the Csn5 subunit of the Cop9 Signalosome.