Microwave-induced effects on superconductors

We have studied the effects of microwave radiation on superconducting tunnel junctions and on the critical currents of superconducting strips at 2.0 and 10.0 GHz. In the tunnel junctions both quantum mechanical and classical effects (photon-induced tunneling and classical rectification, respectively), were observed, but not gap enhancement. The application of microwave radiation on long, superconducting, thin-film bridges was found to increase their critical current. The microwave magnetic field was found to couple more efficiently to the superconductor. The increase in the critical current was found to be proportional to the square root of the incident power.Work supported in part by grants NSF DMR # 76-82347 and ONR NOO14-75-C-0245 P4.     

Replacement of fossil fuels by hydrogen

Up to the end of the century, an export business for photovoltaic solar power stations with an accumulated total power of more than 300 gigawatts could be build up. The profit from the export of these solar-electrical power stations could finance the, at that time, accumulated total costs for the project of $200 billion(US). Included in this financial investment would also be the construction of so-called solar plantation families. After the year 2000, a total of 10 plantation families (each with 10 family members) situated in suitable deserted zones of the world would be capable of reproducing themselves. With this aim, each plantation would use its output of electrical energy to produce solar cells and materials for the construction of 10 new plantations within a decade. This highly technological growth process for identical solar plantation units could be completed in the fourth generation of each plantation family, i.e. about 50 years after the start of construction of the first plantation. From this time on, all 10 plantation families could together, by using their electrical energy for the electrolysis of water, generate an amount of hydrogen per year which would represent four to five times the energy of the world's present annual consumption of oil.     

Fracture assessment of a brittle RPV under cold loading

The oldest Swedish reactor is a boiling water reactor (BWR) with a vessel made of A302 Grade B with rather high Cu and Ni content. These elements have intensified the irradiation embrittlement in the beltline region so that RT_NDT of certain welds may exceed 100 °C at the end-of-life condition. A preliminary study of the fracture risk for the beltline region showed that the limiting loading case would be the cold over-pressurization of the reactor. The objective of this study was to develop a reliable methodology for fracture assessment of the aged reactor vessel under cold loading scenarios. The test program covered experiments on standard SEN(B) specimens and clad beams under uniaxial and biaxial loading. The test material was a reactor vessel steel prepared with a special heat treatment to simulate fracture toughness properties of the aged reactor. No significant effects of shallow crack and biaxial loading were observed on cleavage fracture toughness in different clad specimens. While the ASME K_Ic reference curve was shown to be overly conservative, the Master Curve methodology satisfactorily predicted the experimental outcomes of the test program. The Master Curve methodology indicated that a 20-mm deep surface crack was acceptable in the beltline region under a cold over-pressurization scenario. This value was three times greater than what a methodology based on the ASME K_Ic reference curve yielded.     

Evidence for altered synthesis of type II collagen in patients with osteoarthritis

There is evidence to suggest that the synthesis of type II collagen is increased in osteoarthritis (OA). Using an immunoassay, we show that the content of the C-propeptide of type II procollagen (CPII), released extracellularly from the newly synthesized molecule, is directly related to the synthesis of this molecule in healthy and osteoarthritic articular cartilages. In OA cartilage, CPII content is often markedly elevated (mean 7.6-fold), particularly in the mid and deep zones, reaching 29.6% of the content in newborn. Synthesis is also directly related to total collagen II content in OA, suggesting its importance in maintaining collagen content and cartilage structure. The release of CPII from cartilage is correlated directly with cartilage content. However, the increase in CPII in OA cartilage is not reflected in serum, where a significant reduction is observed. Together these studies provide evidence for alterations in procollagen II synthesis in vivo in patients with OA.     

The constitutive transport element (CTE) of Mason-Pfizer monkey virus (MPMV) accesses a cellular mRNA export pathway

The constitutive transport elements (CTEs) of type D retroviruses are cis-acting elements that promote nuclear export of incompletely spliced mRNAs. Unlike the Rev response element (RRE) of human immunodeficiency virus type 1 (HIV-1), CTEs depend entirely on factors encoded by the host cell genome. We show that an RNA comprised almost entirely of the CTE of Mason-Pfizer monkey virus (CTE RNA) is exported efficiently from Xenopus oocyte nuclei. The CTE RNA and an RNA containing the RRE of HIV-1 (plus Rev) have little effect on export of one another, demonstrating differences in host cell requirements of these two viral mRNA export pathways. Surprisingly, even very low amounts of CTE RNA block export of normal mRNAs, apparently through the sequestration of cellular mRNA export factors. Export of a CTE-containing lariat occurs when wild-type CTE, but not a mutant form, is inserted into the pre-mRNA. The CTE has two symmetric structures, either of which supports export and the titration of mRNA export factors, but both of which are required for maximal inhibition of mRNA export. Two host proteins bind specifically to the CTE but not to non-functional variants, making these proteins candidates for the sequestered mRNA export factors.     

Past, present and future of mobile payments research: A literature review

The mobile payment services markets are currently under transition with a history of numerous tried and failed solutions, and a future of promising but yet uncertain possibilities with potential new technology innovations. At this point of the development, we take a look at the current state of the mobile payment services market from a literature review perspective. We review prior literature on mobile payments, analyze the various factors that impact mobile payment services markets, and suggest directions for future research in this still emerging field. To facilitate the analysis of literature, we propose a framework of four contingency and five competitive force factors, and organize the mobile payment research under the proposed framework. Consumer perspective of mobile payments as well as technical security and trust are best covered by contemporary research. The impacts of social and cultural factors on mobile payments, as well as comparisons between mobile and traditional payment services are entirely uninvestigated issues. Most of the factors outlined by the framework have been addressed by exploratory and early phase studies.     

Proofreading and aminoacylation of tRNAs before export from the nucleus

After synthesis and processing in the nucleus, mature transfer RNAs (tRNAs) are exported to the cytoplasm in a Ran.guanosine triphosphate-dependent manner. Export of defective or immature tRNAs is avoided by monitoring both structure and function of tRNAs in the nucleus, and only tRNAs with mature 5' and 3' ends are exported. All tRNAs examined can be aminoacylated in nuclei of Xenopus oocytes, thereby providing a possible mechanism for functional proofreading of newly made tRNAs. Inhibition of aminoacylation of a specific tRNA retards its appearance in the cytoplasm, indicating that nuclear aminoacylation promotes efficient export.     

HTGR fuel and fuel cycle

This paper describes some of the basic charactritics of the HTGR fuel with emphasis on the 1160 MW(e) plant now being offered commercially by Gulf General Atomic and some of the aspects of the fuel cycle which are unique to the HTGR. The fuel cycle is based on highly enriched (93%) uranium for the initial and the make-up fissile material; thorium for the fertile material, with the bred ²³³U being recycled at the earliest opportunity. The fuel elements consist only of ceramic materials with the thorium/uranium carbides or oxides in the form of coated particles.