MECHANICAL PROPERTIES OF SOME REFRACTORY METALS AND THEIR ALLOYS

A critical evaluation has been made of the available mechanical property data for Nb-, Mo-, Ta-, and W-base alloys. It was fouad that insufficient data are available to allow the design and construction of complex engineering systems involving these materials. A general evaluation of the potential service temperatures for Nb-, Mo-, Ta-, and W-base alloys was made on the basis that conventional a1loys have been used up to two thirds of their absolute melting poirt. Strengthening mechanisms that have been used to achieve high operating temperatures for conventionnl alloys and that could be applied to refractory alloys are discussed. A review of the literature on the effects of irradiation on the mechanical properties of niobium, molybdenum, tantalum, and tungsten has been made. It has been found that the existing data on this topic are rather scant. The data in general show that the ductility of molybdenum, tantalum, and tungsten is reduced after irradiation at ambient temperatures. The yield and ultimate strengths are increased slightiy by irradiation. High-temperature tube- burst tests show that the rupture life of the Nb--1% Zr alloy is not drastically influenced by irradiation. (auth

Asymptotics of Toeplitz Determinants and the Emptiness Formation Probability for the XY Spin Chain

We study an asymptotic behavior of a special correlator known as the Emptiness Formation Probability (EFP) for the one-dimensional anisotropic XY spin-1/2 chain in a transverse magnetic field. This correlator is essentially the probability of formation of a ferromagnetic string of length $n$ in the antiferromagnetic ground state of the chain and plays an important role in the theory of integrable models. For the XY Spin Chain, the correlator can be expressed as the determinant of a Toeplitz matrix and its asymptotical behaviors for $n \to \infty$ throughout the phase diagram are obtained using known theorems and conjectures on Toeplitz determinants. We find that the decay is exponential everywhere in the phase diagram of the XY model except on the critical lines, i.e. where the spectrum is gapless. In these cases, a power-law prefactor with a universal exponent arises in addition to an exponential or Gaussian decay. The latter Gaussian behavior holds on the critical line corresponding to the isotropic XY model, while at the critical value of the magnetic field the EFP decays exponentially. At small anisotropy one has a crossover from the Gaussian to the exponential behavior. We study this crossover using the bosonization approach.Comment: 40 pages, 9 figures, 1 table. The poor quality of some figures is due to arxiv space limitations. If You would like to see the pdf with good quality figures, please contact Fabio Franchini at "[email protected]

Spectral, mineralogical, and geochemical variations across Home Plate, Gusev Crater, Mars indicate high and low temperature alteration

Over the last ~ 3 years in Gusev Crater, Mars, the Spirit rover observed coherent variations in color, mineralogy, and geochemistry across Home Plate, an ~ 80 m-diameter outcrop of basaltic tephra. Observations of Home Plate from orbit and from the summit of Husband Hill reveal clear differences in visible/near-infrared (VNIR) colors between its eastern and western regions that are consistent with mineralogical compositions indicated by Mössbauer spectrometer (MB) and by Miniature Thermal Emission Spectrometer (Mini-TES). Pyroxene and magnetite dominate the east side, while olivine, nanophase Fe oxide (npOx) and glass are more abundant on the western side. Alpha Particle X-Ray Spectrometer (APXS) observations reveal that eastern Home Plate has higher Si/Mg, Al, Zn, Ni, and K, while Cl and Br are higher in the west. We propose that these variations are the result of two distinct alteration regimes that may or may not be temporally related: a localized, higher temperature recrystallization and alteration of the east side of Home Plate and lower temperature alteration of the western side that produced npOx

Development status and potential program for development of proliferation-resistant molten-salt reactors

Preliminary studies of existing and conceptual molten-salt reactor (MSR) designs have led to the identification of conceptual systems that are technologically attractive when operated with denatured uranium as the principal fissile fuel. These denatured MSRs would also have favorable resource-utilization characteristics and substantial resistance to proliferation of weapons-usable nuclear materials. The report presents a summary of the current status of technology and a discussion of the major technical areas of a possible base program to develop commercial denatured MSRs. The general areas treated are (1) reactor design and development, (2) safety and safety related technology, (3) fuel-coolant behavior and fuel processing, and (4) reactor materials. A substantial development effort could lead to authorization for construction of a molten-salt test reactor about 5 years after the start of the program and operation of the unit about 10 years later. A prototype commercial denatured MSR could be expected to begin operating 25 years from the start of the program. The postulated base program would extend over 32 years and would cost about $700 million (1978 dollars, unescalated). Additional costs to construct the MSTR,$600 million, and the prototype commercial plant, $1470 million, would bring the total program cost to about$2.8 billion. Additional allowances probably should be made to cover contingencies and incidental technology areas not explicitly treated in this preliminary review

Binding of Griffonia simplicifolia I lectin to rat pulmonary alveolar macrophages and its use in purifying type II alveolar epithelial cells

We report that the isolectin Griffonia simplicifolia I-B4 isolated from G. simplicifolia seeds binds to rat alveolar macrophages present in frozen sections of lung tissue or bronchoalveolar lavage fluid. G. simplicifolia I-B4 does not bind to alveolar epithelial cells. We established that G. simplicifolia I-B4 binds to the macrophages via interaction with terminal [alpha]--galactopyranosyl residues present on these cells. This was substantiated by demonstrating that binding is inhibited either by the haptenic sugar [alpha]--galactopyranoside or by treating the cells with coffee bean [alpha]-galactosidase. Because murine laminin is known to contain terminal [alpha]--galactopyranosyl end-groups, and because we found that an anti-laminin antiserum binds to rat alveolar macrophages, we suspect that G. simplicifolia I-B4 may be binding to laminin present on the macrophages. To isolate alveolar type II epithelial cells from rat lungs, we developed a method that utilizes the lectin G. simplicifolia I. When proteinase-derived suspensions of pulmonary cells are incubated with G. simplicifolia I, the macrophages agglutinate and can be removed by filtration through nylon mesh. After incubating the resulting cellular suspension in tissue culture, the adherent cells are 94 +/- 2% (S.D.) type II cells. When compared to cells isolated by repeated differential adherence, the lectin-prepared type II cells have similar morphology and staining characteristics, form domes in monolayers and incorporate similar amounts of palmitate into disaturated phosphatidylcholine. We believe that the procedure outlined in this report provides a simple and effective method to isolate type II alveolar epithelial cells from rat lungs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26290/1/0000375.pd

Spectral Characterization of Analog Samples in Anticipation of OSIRIS-REx's Arrival at Bennu

NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission successfully launched on September 8th, 2016. During its rendezvous with near-Earth asteroid (101955) Bennu beginning in 2018, OSIRIS-REx will characterize the asteroid's physical, mineralogical, and chemical properties in an effort to globally map the properties of Bennu, a primitive carbonaceous asteroid, and choose a sampling location [e.g. 1]. In preparation for these observations, we spectrally characterized a suite of analog samples across visible, near- and thermal-infrared wavelengths and used these in initial tests of phase detection and abundance determination software algorithms. Here we present the thermal infrared laboratory measurements of the analog sample suite measured under asteroidlike conditions, which are relevant to the interpretation of spectroscopic observations by the OSIRIS-REx Thermal Emission Spectrometer (OTES) [2, 3]. This suite of laboratory measurements of asteroid analogs under asteroid-like conditions is the first of their kind

Evaluating the effects of bilingual traffic signs on driver performance and safety

Variable Message Signs (VMS) can provide immediate and relevant information to road users and bilingual VMS can provide great flexibility in countries where a significant proportion of the population speak an alternative language to the majority. The study reported here evaluates the effect of various bilingual VMS configurations on driver behaviour and safety. The aim of the study was to determine whether or not the visual distraction associated with bilingual VMS signs of different configurations (length, complexity) impacted on driving performance. A driving simulator was used to allow full control over the scenarios, road environment and sign configuration and both longitudinal and lateral driver performance was assessed. Drivers were able to read one and two-line monolingual signs and two-line bilingual signs without disruption to their driving behaviour. However, drivers significantly reduced their speed in order to read four-line monolingual and four-line bilingual signs, accompanied by an increase in headway to the vehicle in front. This implies that drivers are possibly reading the irrelevant text on the bilingual sign and various methods for reducing this effect are discussed

Insights into the regulation of DMSP synthesis in the diatom Thalassiosira pseudonana through APR activity, proteomics and gene expression analyses on cells acclimating to changes in salinity, light and nitrogen

Despite the importance of dimethylsulphoniopropionate (DMSP) in the global sulphur cycle and climate regulation, the biological pathways underpinning its synthesis in marine phytoplankton remain poorly understood. The intracellular concentration of DMSP increases with increased salinity, increased light intensity and nitrogen starvation in the diatom Thalassiosira pseudonana. We used these conditions to investigate DMSP synthesis at the cellular level via analysis of enzyme activity, gene expression and proteome comparison. The activity of the key sulphur assimilatory enzyme, adenosine 5′- phosphosulphate reductase was not coordinated with increasing intracellular DMSP concentration. Under all three treatments coordination in the expression of sulphur assimilation genes was limited to increases in sulphite reductase transcripts. Similarly, proteomic 2D gel analysis only revealed an increase in phosphoenolpyruvate carboxylase following increases in DMSP concentration. Our findings suggest that increased sulphur assimilation might not be required for increased DMSP synthesis, instead the availability of carbon and nitrogen substrates may be important in the regulation of this pathway. This contrasts with the regulation of sulphur metabolism in higher plants, which generally involves upregulation of several sulphur assimilatory enzymes. In T. pseudonana changes relating to sulphur metabolism were specific to the individual treatments and, given that little coordination was seen in transcript and protein responses across the three growth conditions, different patterns of regulation might be responsible for the increase in DMSP concentration seen under each treatment

Socio-demographic and behavioural characteristics of illegal motorcycle street racers in Malaysia

<p>Abstract</p> <p>Background</p> <p>This study sought to understand the factors associated with street racing among the illegal motorcycle racers in Malaysia or known as the <it>"Mat Rempit"</it>.</p> <p>Methods</p> <p>Street outreach interviewer-administered surveys were conducted from June 2008 to January 2009 in this multi-state study.</p> <p>Results</p> <p>A total of 2022 participants were surveyed, the mean ± <it>SD </it>age of the participants was 20.5 ± 3.4 years (age range: 12 to 35 years). Mean duration of street racing was 2.65(<it>SD </it>± 1.77) years (range: 2 months to 12 years), with 50.1% and 35.8% reporting stunt riding and alcohol drinking while racing, respectively. With regard to risk behaviours, cigarette smoking was highly prevalent among the study participants (78.3%), followed by alcohol drinking (27.8%) and recreational drug use (18.8%). Participants scored high on the masculinity scale (15.7 ± 4.0 out of 21.0). The results of the logistic regression analysis showed that socio-demographic variables, risk behaviour and masculinity scores were associated with racing frequency.</p> <p>Conclusion</p> <p>Given these associations, tailoring family-centered interventions to the needs of the lower socio-economic groups and interventions recognizing the negative consequences of health risk behaviours related to street racing as an expression of traditional masculinity should be emphasized.</p

March 1955

Presidents Report - Frank P. Dunlap (page 1) The Student Purdue Serves - Dr. N. M. Parkhurst (2) A Student Reports - Bill Roach (4) Corrective Management of Shrubs - H. W. Gilbert (5) Nutrient Absorption by Plants - J. R. Watson Jr. (7) Disease Development is Slow - Dr. Wm. Klomparens (10) Poa Annua Control with Arsenic Materials - W. H. Daniel (11) Labor Relations - Cincinnati Country Club - John McCoy (14) Labor Policies at my Course - Ernest Schneider (15) Labor Policies at my Course - Don Strand (16) Nitrogen Use and Why - Robert M. Williams (17) Fertilizing Greens and Why - Don Likes(18) Nitrogen Use and Why - Lawrence Huber (20) Report on Experimental Green - Taylor Boyd (21) Experiences with Fairway Improvements - Ray Davis (23) Fairway Improvement Program - Bert Rost (24) Experiences on Merion Bluegrass - Carl Habenicht (24) Merion Bluegrass Experiences - P. E. Drachman (25) Zoysia for Lawns and Nurseries - P. E. Drachman (27) Preparation for Mortorized Carts - James W. Brandt (28) Preparing for Motorized Carts - Carl Bretzlaff (29) Merion Bluegrass Experiences - Ben O. Warren (31) Pennlu Distribution - W. H. Daniel(32) Zoysia for Midwest Lawns - W. H. Daniel (34) Crabgrass Prevention and Control - W. H. Daniel (36) Plant Carbohydrates Must Balance Nitrogen - M. R. Teel (39) Put Yourself in His Place - Fred Grau (40) Nitrogen Use and Why Wm. E. Lyons (45) The Management of Bentgrass Fairways - O. J. Noer (49) Fairway Improvement Program O. W. Young (52) Experiences with Zoysia - Ferank Dinelli (53