Anomalous strain effect in heteroepitaxial SrRuO_(3) films on(111) SrTiO_(3) substrates

We report comprehensive investigations into the structure of high-quality(111)-oriented SrRuO_(3)films on SrTiO_(3)substrates to elucidate the effect of(111)heteroepitaxial strain.We found that SrRuO_(3)film with a thickness of~40 nm is compressively strained in plane on the substrate with full coherency.Nevertheless,the out-of-plane spacing is almost the same as in the bulk,which is at odds with the conventional paradigm.By probing a series of half-order Bragg reflections using synchrotron-based x-ray diffraction combined with analyses of the scanning transmission electron microscopy images,we discovered that the heteroepitaxial strain is accommodated via significant suppression of the degree of c+octahedral tilting and the formation of three equivalent domain structures on the(111)SrTiO_(3)substrate.This anomalous effect sheds light on the understanding of an unconventional paradigm of film-substrate coupling for the(111)heteroepitaxial strain.

Resource Evaluation of Heavy Rare Earth Derived from the Spent Gd203 Burnable Poison in LWRs

A burnup calculation has been performed to evaluate heavy rare earth （terbium--Tb, dysprosium--Dy） production in spent gadolinium oxide （Gd203） installed as a BP （burnable poison）. Each amount of Tb and Dy production derived from the BP has been about 30-40 times larger than those created in FP （fission products）. Required cooling time to achieve exemption level on radioactivity concentration produced Tb and Dy derived from the BP are much shorter （BP-Tb： 7.9y, BP-Dy： 〈 0.1y） than those created in FP （FP-Tb： 3,616y, FP-Dy： 6.9y）. However, the BP is mixed homogeneously with UO2 pellet in current nuclear fuel system of LWRs （light water reactors）, and hence mixing of FP cannot be not avoided. In such a mixture case, the required cooling time of recovered Tb will become 2,653y and that of recovered Dy be 4.8y. For this reason, recovered Tb is unlikely to be resource for utilization, while recovered Dy must be the resource provided the precise separation from the other FP.

Distance Between α-Orientations of Plane Graphs by Facial Cycle Reversals

Cycle reversal had been shown as a powerful method to deal with the relation among orientations of a graph since it preserves the out-degree of each vertex and the connectivity of the orientations. A facial cycle reversal on an orientation of a plane graph is an operation that reverses all the directions of the edges of a directed facial cycle. An orientation of a graph is called an α-orientation if each vertex admits a prescribed out-degree. In this paper, we give an explicit formula for the minimum number of the facial cycle reversals needed to transform one α-orientation into another for plane graphs.