HIV-1 Nef protein: purification, crystallizations, and preliminary X-ray diffraction studies

Human immunodeficiency virus Nef protein accelerates virulent progression of AIDS by its interaction with specific cellular proteins involved in cellular activation and signal transduction. Here we report the purification and crystallization of the conserved core of HIV-1LAI Nef protein in the unliganded form and in complex with the wild-type SH3 domain of the P59fyn protein-tyrosine kinase. One-dimensional NMR experiments show that full-length protein and truncated fragment corresponding to the product of HIV-1 protease cleavage have a well-folded compact tertiary structure. The ligand-free HIV-1 Nefcore protein forms cubic crystals belonging to space group P23 with unit cell dimensions of a = b = c = 86.4 A. The Nef-Fyn SH3 cocrystals belong to the space group P6(1)22 or its enantiomorph, P6(5)22, with unit cell dimensions of a = b = 108.2 A and c = 223.7 A. Both crystal forms diffract to a resolution limit of 3.0 A resolution using synchrotron radiation, and are thus suitable for X-ray structure determination.     

Chemically based model to predict distribution coefficients in the Cu-LIX 65N and Cu-KELEX 100 systems

A chemically based thermodynamic model to predict the distribution coefficients have been developed for the Cu-LIX 65N and Cu-KELEX 100 systems. The predictive model makes use of the aqueous phase cupric sulfate complex stoichiometric stability constant expressed as its degree of formation, their extraction mechanism, and the equilibrium constant for the extraction reaction. The distribution coefficient of copper can be predicted by the equationK _d =κ₁α₀ϕ², where ϕ is the ratio of the equilibrated organic concentration to the equilibrated hydrogen ion concentration in the aqueous phase,k ₁ is the effective equilibrium constant containing the quotient of the activity coefficients of the reacting species and α₀ is the degree of formation of the free cupric ion in the equilibrated aqueous phase. Excellent agreement between the experimental data and the predicted values was obtained.     

Influence of temperature on the extraction of zinc by LIX 34

The influence of temperature on the extraction of zinc by LIX 34 diluted with Kermac 470B has been investigated. The results indicate that the extraction is exothermic and the stripping is endothermic. The results also show that the highest percentage extraction of metal ion gives the smallest value of ΔH     

Dry developable resist in e-beam and sr lithography

Dry developable resists comprised of poly(methyl isopropenyl ketone) (PMIPK) and 4-methyl-2,6-dI-(4′-azldoben-zylidene)-cyclohexanone-1 gave excellent results in SK lithography, i. e., high aspect ratio resist patterns with vertical walls were easily obtained by maskless dry etching in the single layer resist process. Because of the simplicity of single layer resist processing and the high etch rate in maskless dry etching for the formation of thick resist patterns, the dry developable resist in SR lithography may be advantageous to the multilayer resist for the purpose of generating high resolution, thick resist patterns with vertical walls. The resolution limit of the dry developable resist which reproduces the designed dimensions was 100 nm line and 200 nm space when a conventional e-beam apparatus was used at 20 KV in the dry developable multilayer resist process.     

Misorientation‐Angle‐Dependent Phase Transformation in van der Waals Multilayers via Electron‐Beam Irradiation

Misorientation‐angle dependence on layer thickness is an intriguing feature of van der Waals materials, which causes stark optical gain and electrical transport modulation. However, the influence of misorientation angle on phase transformation is not determined yet. Herein, this phenomenon in a MoS₂ multilayer via in situ electron‐beam irradiation is reported. An AA′‐stacked MoS₂ bilayer undergoes structural transformation from the 2H semiconducting phase to the 1T′ metallic phase, similar to a MoS₂ monolayer, which is confirmed via in situ transmission electron microscopy. Moreover, non‐AA′ stacking, which has no local AA′ stacking order in the Moiré pattern, does not reveal such a phase transformation. While a collective sliding motion of chalcogen atoms easily occurs during the transformation in AA′ stacking, in non‐AA′ stacking it is suppressed by the weak van der Waals strength and by the chalcogen atoms interlocked at different orientations, which disfavor their kinetics by the increased entropy of mixing.     

18-FDG imaging in breast cancer

A previously isolated parsley (Petroselinum crispum) cDNA with high sequence similarity to cinnamate 4-hydroxylase (C4H) cDNAs from several plant sources was expressed in yeast (Saccharomyces cerevisiae) containing a plant NADPH:cytochrome P450 oxidoreductase and verified as encoding a functional C4H (CYP73A10). Low genomic complexity and the occurrence of a single type of cDNA suggest the existence of only one C4H gene in parsley. The encoded mRNA and protein, in contrast to those of a functionally related NADPH:cytochrome P450 oxidoreductase, were strictly coregulated with phenylalanine ammonia-lyase mRNA and protein, respectively, as demonstrated by coinduction under various conditions and colocalization in situ in cross-sections from several different parsley tissues. These results support the hypothesis that the genes encoding the core reactions of phenylpropanoid metabolism form a tight regulatory unit.     

Short Channel Characteristics of Gallium–Indium–Zinc–Oxide Thin Film Transistors for Three-Dimensional Stacking Memory

Amorphous gallium-indium-zinc-oxide (GIZO) thin film transistors with short channels of 50 nm were successfully fabricated by e-beam lithographic patterning. The GIZO thin film transistors showed a high mobility of 8.2 cm²/Vldrs with on-to-off current ratios up to 10⁶. Excellent short channel characteristics were also obtained with a small shift of the threshold voltages and no degradation of subthreshold slopes as V_DS increased, even with short channel lengths of less than 100 nm. These promising results indicate that the GIZO thin film transistors could be a candidate for selection transistors in 3-D cross point stacking memory.