Modification of primary structures of hairpin ribozymes for probing active conformations

Hairpin ribozymes consist of two stem-loop domains, and these domains are assumed to interact with each other to produce the self-cleavage activity. We have studied the relationship of the tertiary structure of the hairpin ribozyme and the cleavage activity by dividing and re-joining the domains. A hairpin ribozyme (E50) was divided at the hinge region, and the main part was joined to a substrate (S1) using tri- or penta-cytidylates. These ribozymes retained the cleavage activity in the presence of the rest of the molecule, indicating that the active conformation could be maintained if the two domains interacted with each other. Based on the these results, we designed a new type of hairpin ribozyme by replacing one of the domains. To maintain the interaction of the domains, oligocytidylates were inserted at a junction. These reversely jointed ribozyme complexes showed cleavage activity that was dependent on the linker lengths. These modifications in the primary structure of the hairpin ribozyme confirm the structural requirement for the catalytic reaction and provide information for the correlation of the tertiary structure with the cleavage of the hairpin ribozyme.     

Isolation of a new antibiotic, laterosporamine. Studies on antibiotics from the genus Bacillus. XIII

A new antibiotic, named laterosporamine, was isolated from the culture broth of Bacillus laterosporus 340-19. The antibiotic is active against Gram-positive and Gram-negative bacteria in vitro and in vivo. It is a water-soluble basic substance, positive to ninhydrin, SAKAGUCHI'S and DRAGENDORFF'S reagents. A non-peptidic structure with an approximate empirical formula C17H35N7O4 was suggested.     

Magnetic properties and Mössbauer effect in 12-layer hexagonal BaFeO3

A 12-layer hexagonal perovskite BaFeO₃ with a=5.700 and c=28.03A has been synthesized at high oxygen pressures and temperatures. Néel temperature, paramagnetic Curie temperature and the effective Bohr magneton of the material were determined to be 172K, 130K and 5.05μ_B respectively.     

The torsion of an infinite hollow cylinder with an external crack

This paper deals with the axially symmetric torsion of a hollow cylinder with an external crack. The mixed boundary value problem is reduced to a pair of dual series equations. These equations are shown to be equivalent to an infinite system of simultaneous equations. Numerical results are presented for stresses, displacement and stress intensity factors.     

Experimental analysis of the power curve sensitivity test series at ROSA-III

The rig of safety assessment (ROSA)-III facility is a volumetrically scaled (1/424) boiling water reactor (BWR/6) system with an electrically heated core designed for integral loss-of-coolant accident (LOCA) and emergency core cooling system (ECCS) tests. Seven recirculation pump suction line break LOCA experiments were conducted at the ROSA-III facility in order to examine the effect of the initial stored heat of a fuel rod on the peak cladding temperature (PCT). The break size was changed from 200% to 5% in the test series and a failure of a high pressure core spray (HPCS) diesel generator was assumed. Three power curves which represented conservative, realistic and zero initial stored heat, respectively, were used.In a large break LOCA such as 200% or 50% breaks, the initial stored heat in a fuel rod has a large effect on the cladding surface temperature because core uncovery occurs before all the initial stored heat is released, whereas in a small break LOCA such as a 5% break little effect is observed because core uncovery occurs after the initial stored heat is released. The maximum PCTs for the conservative initial stored heat case was 925 K, obtained in the 50% break experiment, and that for the realistic initial stored heat case was 835 K, obtained in the 5% break experiment.     

Untersuchung über die Fortpflanzungserscheinungen in einer unsymmetrischen Mehrpolleitung als Entwicklung der Mehrpolleitungstheorie

Zusammenfassung Mit Hilfe der Tatsache, daß man zwei symmetrische Mehrpolleitungen aus einer unsymmetrischen Mehrpolleitung herleiten kann, wurde auf Grund der früher entwickelten Mehrpolleitungstheorie bewiesen, daß die vorgelegte unsymmetrische Mehrpolleitung gleichfalls in ein System von selbständigen unsymmetrischen Vierpolen zerlegt werden kann. Dabei wurde ein Verfahren zur Festsetzung der Separationsmatrizen und der Konstanten der getrennten Vierpole angegeben.Doch ist es bei einer Kette der unsymmetrischen Mehrpolleitung noch nicht gelungen, die im symmetrischen bzw. quasisymmetrischen Falle geltende De Moivresche Beziehung der Ketten- oder Iterationsmatrix aufzustellen, denn die unsymmetrische Mehrpolleitung erhält am Sender und Empfänger verschiedene Separationsmatrizen und die Iterationsmatrix der Kette kann nur in ihrer Produktform ausgerechnet werden.In der vorliegenden Abhandlung wurden die Abschlußzustände der Leitung besonders berücksichtigt. Es war eine der Hauptaufgaben dieser Arbeit, die Spannungen und Ströme bei einem gegebenen Abschluß auf der Sender- bzw. Empfängerseite zu bestimmen; es ist also von verschiedenen Scheinwiderständen, den Übersetzungsmatrizen und den Reflexionserscheinungen die Rede gewesen.Bei der Bearbeitung dieses Gegenstandes habe ich an verschiedenen Stellen Herrn Dr. R. Feldkellers Buch Einführung in die Vierpoltheorie benutzt, und ich halte es für meine angenehme Pflicht, dem Verfasser dieses schönen Buches hiermit meinen herzlichsten Dank auszusprechen.Ich darf hier fernerhin den Namen des Herrn Professor D. K. W. Wagner nicht unerwähnt lassen, dem ich, jetzt, wo dieser Mehrpolleitungstheorie wenigstens in bezug auf ihre Grundsätze, ich glaube, eine Geschlossenheit gegeben worden ist, ganz besonders zum Danke verpflichtet bin, da ich im ja beinahe alles verdanke, Durchlesung sowohl des vorliegenden Manuskriptes als auch des der ersten Abhandlung, Überarbeitung des sprachlichen Ausdrucks, geben die Gelegenheit zur Veröffentlichung der Arbeiten in dieser berühmten Zeitschrift.     

MEG spatio-temporal analysis using a covariance matrix calculated from nonaveraged multiple-epoch data

We propose a magnetoencephalographic (MEG) spatio-temporal analysis in which the measurement-covariance matrix is calculated using nonaveraged multiple epoch data. The proposed analysis has two advantages. First, a very narrow time window can be used for the source estimation. Second, accurate localization is possible even when the source activation has a time jitter. Experiments using auditory evoked MEG data clearly demonstrate these advantages.     

Giant Rashba-type spin splitting in bulk BiTeI

There has been increasing interest in phenomena emerging from relativistic electrons in a solid, which have a potential impact on spintronics and magnetoelectrics. One example is the Rashba effect, which lifts the electron-spin degeneracy as a consequence of spin-orbit interaction under broken inversion symmetry. A high-energy-scale Rashba spin splitting is highly desirable for enhancing the coupling between electron spins and electricity relevant for spintronic functions. Here we describe the finding of a huge spin-orbit interaction effect in a polar semiconductor composed of heavy elements, BiTeI, where the bulk carriers are ruled by large Rashba-like spin splitting. The band splitting and its spin polarization obtained by spin- and angle-resolved photoemission spectroscopy are well in accord with relativistic first-principles calculations, confirming that the spin splitting is indeed derived from bulk atomic configurations. Together with the feasibility of carrier-doping control, the giant-Rashba semiconductor BiTeI possesses excellent potential for application to various spin-dependent electronic functions.     

Time and spatial heat transfer performance around an isothermally heated sphere placed in a uniform, downwardly directed flow (in relation to the enhancement of latent heat storage rate in a spherical capsule)

The aim of this study is to reveal the temporal and spatial heat transfer performance of an isothermally heated sphere placed in a uniform, downwardly directed flow using a micro-foil heat flow sensor (HFS). A HFS, whose response time is about 0.02 s, was pasted on the surface of a heated copper sphere. Experiments were carried out using air with a Grashof number of 3.3 × 10⁵ and with several Reynolds numbers (Re) up to 1800. Three flow patterns appeared: a chaotic flow at Re<240; a two-dimensional steady separated flow at 240 Re<500, and a three-dimensional unsteady separated flow at Re 500. In addition, the instantaneous and time-averaged heat transfer performance around the sphere in each of the three regions was clarified. Next, enhancement of the latent heat storage rate of a solid phase change material (PCM) in a spherical capsule was performed. The flow around the spherical capsule, in which the solid PCM was filled and placed in a heated, upwardly directed flow, is the approximate adverse flow phenomenon around the heated sphere which was placed in a downwardly directed flow. In other words, the buoyant flow and the forced flow are in the opposite directions in these two cases. Tests of latent heat storage were run for two Reynolds numbers which represented different flow characteristics in the heat transfer experiments, Re=150 and 1800. Furthermore, copper plates were inserted into the solid PCM, of which thermal conductivity was considerably low, to enhance the latent heat storage rate for the two Reynolds number flows.