Overgrowth of GaN on Be-doped coalesced GaN nanocolumn layer by rf-plasma-assisted molecular-beam epitaxy—Formation of high-quality GaN microcolumns

GaN crystals were overgrown on GaN nanocolumn platforms with a Be-doped coalesced layer by rf-plasma-assisted molecular-beam epitaxy (rf-MBE). The overgrown GaN included large micrometer-scale hexagonal columnar crystals. These microcrystals were named ‘microcolumns’ and showed high optical properties comparable to those of GaN bulk crystals grown by hydride vapor phase epitaxy (HVPE).     

Comparison of the variations in the intensity of global electromagnetic resonance and ground surface temperature

We compare the dynamics of the intensity of the global electromagnetic (Schumann) resonance monitored in Japan with the global ground surface temperature (GST) over the period from November 1998 to May 2002. It is shown that the Schumann resonance (SR) intensity varies coherently with the ground surface temperature at mid-latitudes: the relevant cross-correlation coefficient exceeds 0.8. The linear correlation of data decreases with a decreasing latitude interval. We applied the principal component analysis (PCA) to distinguish inter-annual trends (anomalies) in the records from the periodic annual and semi-annual variations. The annual component of the SR intensity behaves similarly to the mid-latitude GST, while the inter-annual variations in the electromagnetic data are similar to those of the GST in the tropics. The regression analysis allowed us to obtain the analytical expressions relating the SR intensity with both the mid-latitude and low-latitude GST. Application of these equations allowed us to retrieve the observed SR pattern from the ground surface temperature and to “reconstruct” the variations in the tropical GST from recorded SR intensity. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 12, pp. 1035–1050, December 2008.     

Molecular devices for high fidelity of DNA replication and gene expression

Certain types of DNA lesions, produced through cellular metabolic processes and also by external environmental stresses, are responsible for the induction of mutations as well as of cancer. Most of these lesions can be eliminated by DNA repair enzymes, and cells carrying the remaining DNA lesions are subjected to apoptosis. The persistence of damaged bases in RNA can cause errors in gene expression, and the cells appear to possess a mechanism which can prevent damaged RNA molecules from entering the translation process. We have investigated these processes for high fidelity of DNA replication and gene expression, by using both biochemical and genetic means. We herein describe (1) the molecular mechanisms for accurate DNA synthesis, (2) mammalian proteins for sanitizing the DNA precursor pool, (3) error avoidance mechanisms for gene expression under oxidative stress, and (4) the roles of DNA repair and apoptosis in the prevention of cancer.     

Dibutyltin dimethoxide-catalyzed aldol reaction of enol trichloroacetates

A catalytic aldol condensation of aldehydes with enol trichloroacetates was achieved using dibutyltin dimethoxide as a novel catalyst in a mixed solvent consisting of THF and MeOH. Various β-hydroxy ketones were diastereoselectively obtained in high yields up to 99%.     

A note on extensions of algebraic and formal groups I

Partially supported by Grant-in-Aid for Scientific Research #62540066