Design and Modeling of Symmetric Three Branch Polymer Planar Optical Power Dividers

Two types of polymer-based three-branch symmetric planar optical power dividers (splitters) were designed, multimode interference (MMI) splitter and triangular shape-spacing splitter. By means of modeling the real structures were simulated as made of Epoxy Novolak Resin on silicon substrate, with silica buffer layer and polymethylmethacrylate as protection cover layer. The design of polymer waveguide structure was done by Beam Propagation Method. After comparing properties of both types of the splitters we have demonstrated that our new polymer based triangular shaped splitter can work simultaneously in broader spectrum, the only condition would be that the waveguides are single-mode guiding. It practically means that, what concerns communication wavelengths, it can on principle simultaneously operate at two mainly used wavelengths, 1310 and 1550 nm

Live Hog-Carcass Evaluation

The values placed on the various grades and weights of market hogs are dependent primarily on two factors: (1) the amount of lean in the animal compared to the amount of fat (2) the amount of fill

Erection of a Stainless-Steel Tank for Storing a Phosphoric Acid

A storage tank for 93 % phosphoric acid was built in Luka Koper from 7 mm thick ground hot-rolled plates of 316L stainless steel. The capacity of the storage tank is of the 750 m3, diameter of 11 m and the height of 8,2 m. The shell plates were welded manually using the shielded metal-arc and gas-metal-arc processes. Before the erection, welding procedure tests according to EN 288-3 were carried out. During the construction several non-destructive examination methods were used, such as radiographic testing and visual and liquid penetrant examination. After the entire tank and roof structure were completed, a hydrostatic leak test was carried out. The surfaces of all the welds on the internal surface of the vessel were ground and the roughness was checked on site. The surfaces of the base material and the ground welds were passivated and tested for resistance to corrosion with electrochemical measurements

RNA packaging motor: From structure to quantum mechanical modelling and sequential-stochastic mechanism

The bacteriophages of the Cystoviridae family package their single stranded RNA genomic precursors into empty capsid (procapsids) using a hexameric packaging ATPase motor (P4). This molecular motor shares sequence and structural similarity with RecA-like hexameric helicases. A concerted structural, mutational and kinetic analysis helped to define the mechanical reaction coordinate, i.e. the conformational changes associated with RNA translocation. The results also allowed us to propose a possible scheme of coupling between ATP hydrolysis and translocation which requires the cooperative action of three consecutive subunits. Here, we first test this model by preparing hexamers with defined proportions of wild type and mutant subunits and measuring their activity. Then, we develop a stochastic kinetic model which accounts for the catalytic cooperativity of the P4 hexamer. Finally, we use the available structural information to construct a quantum-chemical model of the chemical reaction coordinate and obtain a detailed description of the electron density changes during ATP hydrolysis. The model explains the results of the mutational analyses and yields new insights into the role of several conserved residues within the ATP binding pocket. These hypotheses will guide future experimental work

Ensuring Safe Exploration: Ares Launch Vehicle Integrated Vehicle Ground Vibration Testing

Ground vibration testing has been an integral tool for developing new launch vehicles throughout the space age. Several launch vehicles have been lost due to problems that would have been detected by early vibration testing, including Ariane 5, Delta III, and Falcon 1. NASA will leverage experience and testing hardware developed during the Saturn and Shuttle programs to perform ground vibration testing (GVT) on the Ares I crew launch vehicle and Ares V cargo launch vehicle stacks. NASA performed dynamic vehicle testing (DVT) for Saturn and mated vehicle ground vibration testing (MVGVT) for Shuttle at the Dynamic Test Stand (Test Stand 4550) at Marshall Space Flight Center (MSFC) in Huntsville, Alabama, and is now modifying that facility to support Ares I integrated vehicle ground vibration testing (IVGVT) beginning in 2012. The Ares IVGVT schedule shows most of its work being completed between 2010 and 2014. Integrated 2nd Stage Ares IVGVT will begin in 2012 and IVGVT of the entire Ares launch stack will begin in 2013. The IVGVT data is needed for the human-rated Orion launch vehicle's Design Certification Review (DCR) in early 2015. During the Apollo program, GVT detected several serious design concerns, which NASA was able to address before Saturn V flew, eliminating costly failures and potential losses of mission or crew. During the late 1970s, Test Stand 4550 was modified to support the four-body structure of the Space Shuttle. Vibration testing confirmed that the vehicle's mode shapes and frequencies were better than analytical models suggested, however, the testing also identified challenges with the rate gyro assemblies, which could have created flight instability and possibly resulted in loss of the vehicle. Today, NASA has begun modifying Test Stand 4550 to accommodate Ares I, including removing platforms needed for Shuttle testing and upgrading the dynamic test facilities to characterize the mode shapes and resonant frequencies of the vehicle. The IVGVT team expects to collect important information about the new launch vehicles, greatly increasing astronaut safety as NASA prepares to explore the Moon and beyond

Pork Carcass Composition as Influenced by Slaughter Weight

The common goal for those engaged in producing and processing pork should be the efficient production of a product which ultimately is highly desirable to the consumer. This means that any retail pork item must be lean, attractive to the eye and yet be very tasty. This study, concerned with changes in body composition, is a portion of a larger project concerned with more efficient production and utilization of pork

Evidence that avian reovirus σNS is an RNA chaperone: implications for genome segment assortment.

Reoviruses are important human, animal and plant pathogens having 10-12 segments of double-stranded genomic RNA. The mechanisms controlling the assortment and packaging of genomic segments in these viruses, remain poorly understood. RNA-protein and RNA-RNA interactions between viral genomic segment precursors have been implicated in the process. While non-structural viral RNA-binding proteins, such as avian reovirus σNS, are essential for virus replication, the mechanism by which they assist packaging is unclear. Here we demonstrate that σNS assembles into stable elongated hexamers in vitro, which bind single-stranded nucleic acids with high affinity, but little sequence specificity. Using ensemble and single molecule fluorescence spectroscopy, we show that σNS also binds to a partially double-stranded RNA, resulting in gradual helix unwinding. The hexamer can bind multiple RNA molecules and exhibits strand-annealing activity, thus mediating conversion of metastable, intramolecular stem-loops into more stable heteroduplexes. We demonstrate that the ARV σNS acts as an RNA chaperone facilitating specific RNA-RNA interactions between genomic precursors during segment assortment and packaging

Charpy udarna žilavost i tvrdoća odžarenog materijala i donjeg bainita

A high strength low alloyed (HSLA) V-Nb steel was heat treated to martensite and lower bainite with different grain size, reheated for 3 seconds at 750 °C and air cooled. Charpy notch tests were performed from -100 °C to 60 °C and the hardness assessed at room temperature. For as delivered steel and lower bainite, the upper shelf toughness was above 200 J and the transition temperature low, while, for martensite the upper shelf toughness threshold was aproximateky at 0 °C. After reheating, notch toughness was decreased moderatly for martensite and strongly for lower bainite. Independently on grain size, lower bainite was more propensive than martensite to embritlement after short reheating in the (α + β) range. For martensite, the change of notch toughness was not related to change of hardness, as by lower hardness lower, also toughness was lower.Nisko legirani V-Nb čelik visoke čvrstoće (HSLA) je toplinsko obrađen na martenzit i bainit sa različitom veličinom zrna, odžaren 3 sekunde na 750 °C i ohlađen na zraku. Chapy žilavost je određena u intervalu od -100 °C do 60 °C, a tvrdoća kod sobne temperature. Kod čelika sa početnom mikrostrukturom čelika i donjeg bainita, je bila veoma visoka žilavost iznad 200 J i tranzicijska temperatura niska, dok je bio kod martenzita prag približno kod 0 °C. Poslije odžarivanja se je žilavost smanjila malo kod martenzita i jako kod bainita. Nezavisno od veličine zrna, donji bainit je bio mnogo osetljiviji na pojavu krtosti poslije kratkog odžarivanja u području (α + β). Kod martenzita, promjena žilavosti nije u vezi za tvrdoćom, jer kod niže žilavosti je niža i tvrdoća