Cellular UDP-glucose deficiency caused by a single point mutation in the UDP-glucose pyrophosphorylase gene

We previously isolated a mutant cell that is the only mammalian cell reported to have a persistently low level of UDP-glucose. In this work we obtained a spontaneous revertant whose UDP-glucose level lies between those found in the wild type and the mutant cell. The activity of UDP-glucose pyrophosphorylase (UDPG:PP), the enzyme that catalyzes the formation of UDP-glucose, was in the mutant 4% and in the revertant 56% of the activity found in the wild type cell. Sequence analysis of UDPG: PP cDNAs from the mutant cell showed one missense mutation, which changes amino acid residue 115 from glycine to aspartic acid. The substituted glycine is located within the largest stretch of strictly conserved residues among eukaryotic UDPG:PPs. The analysis of the cDNAs from the revertant cell indicated the presence of an equimolar mixture of the wild type and the mutated mRNAs, suggesting that the mutation has reverted in only one of the alleles. In summary, we demonstrate that the G115D substitution in the Chinese hamster UDPG:PP dramatically impairs its enzymatic activity, thereby causing cellular UDP-glucose deficiency.     

Influence of the intensity of gg irradiation on the photoluminescence of GaAs:Te

The influence of gg irradiation (⁶⁰Co) of various intensities (P _γ≈1.7−7.5kGR/h) on the photoluminescence of GaAs:Te single crystals [n ₀=(1.2–2.3×10¹⁸ cm⁻³] is investigated. Together with the known photoluminescence impurity bands (hν _max≈1.2 eV and/or hν _max≈1.35 eV) and edge band (hν _max≈1.51 eV), new bands are also observed in the spectra at hν _max≈1.3 eV and hν _max≈1.48 eV. The observed effects are attributed to radiation-stimulated ordering of the donor impurity and deep impurity centers. Fiz. Tekh. Poluprovodn. 32, 38–39 (January 1998)     

Specific heat at the spin-peierls transition in CuGeO3 under magnetic fields up to 22 tesla

We report on heat capacity measurements of the spin-Peierls compound CuGeO₃ under magnetic fields between 0 and 22 teslas. We have determined the magnetic phase diagram between the three different phases (U=uniform,I=incommensurate,D=dimerised) of this system, unknown up to now forH>14 T, and which can be well interpreted within the Hartree-Fock approximation. We have studied the 2nd order phase transition forH=const. at the crossing ofD-U andI-U phases. The spin-Peierls transition gives rise to a well pronounced specific heat jump. The phase diagram and the specific heat results are discussed in the framework of a B.C.S.-like theoretical model.     

On the Yustova threshold plates

A response to criticism of threshold plates for the study of color vision developed at the Mendeleev All-Russia Research Institute of Metrology and published in 1994 is presented. The critics base their conclusions on colorimetric testing and the examination of the plates. In response to the article by M. V. Danilova and J. D. Mollon [4]. __________ Translated from Izmeritel’naya Tekhnika, No. 1, pp. 37–39, January, 2007.     

Effect of the properties of the water sorbent on the heat generation in the Fe-C-NaCl-H<Subscript>2</Subscript>O-O<Subscript>2</Subscript> system

The water adsorption and retention behaviors of vermiculite, silica gel, activated carbon, and a zeolite are analyzed in relation to their pore structures, and their effects on the dynamics of heat generation in Fe-C-NaCl-H₂O-O₂-water sorbent systems are investigated.     

Optimizing the service life of drill-collar joints on the basis of fracture mechanics criteria

A method of calculation of the lifetime of fish-mouth collar joints has been proposed that is based on selecting a model and using the criteria of fracture mechanics. By this method it is possible to optimize the design parameters of collar joints as a function of the cyclic crack resistance of steels. It is shown that the lifetime of a collar joint with a fatigue crack can be predicted, and the size of the crack can be estimated for a certain operating time of the collar joint. The critical values of the length of a fatigue crack were calculated for various types and dimensions of collar joints, which is important in fixing the periodicity of crack detection operations.     

Interaction Between a Drying Agent and Particles Dispersed by an Airstream Atomizer Inside a Drying Chamber

Results of an experimental study of the aerodynamics and spray density distribution of a liquid dispersed by an airstream atomizer inside a drying chamber. Velocity components of the drying agent and their radial distributions as a function of the distance from the spray plane are determined. Relationships for the distribution of dispersed liquid inside the drying chamber are derived. Interactions between the drying agent and the product in the drying chamber are analyzed.     

Extreme value analysis of epoch maxima—convergence, and choice of asymptote

Cramer's methodology is used to derive the Type I and Type III extreme value asymptotes. The method demonstrates that both methods involve a common limiting process followed in each case by an appropriate approximation of the parent. This highlights the importance of convergence if good predictions of design values are to be obtained.It is shown that the Type III asymptote requires not just an upper limit but quite stringent mathematical conditions to hold at that limit. This implies the need to demonstrate that the underlying physics exist to create such a limit. An alternative class of right-limited distributions exists which have the Type I asymptote, and are equally if not more plausible models for phenomena right-limited by a physical effect. This class cannot be distinguished from Type III unless the parent is known. Poorly converged Type I examples are also indistinguishable from Type III, if the observations are well below the upper limit. The conclusion is that pursuit of the Type III option should be abandoned. Ensuring proper pre-conditioning before fitting the Type I asymptote offers better prospects for fitting observed extremes.