High temperature thermocouple operates in reduction atmosphere

Thermocouple continuously measures a flowing gas up to 4500 degrees F in a hazardous environment. The thermocouple combines rhenium and tungsten in the probe, housing, and swaged extension lead. The wires extend continuously from the cold junction to the probe tip to eliminate errors from secondary thermocouple effects

Inexpensive high-temperature furnace for thermocouple calibration

New furnace calibrates unknown thermocouple by comparing its electrical output to a reference thermocouple /previously calibrated by optical pyrometry/, as both are heated simultaneously. Thermocouples may be radioactive, thus heat source must be accessible by remote manipulation and inspection measurements. Advantages of furnace operation are cited

High-temperature rapid-response thermocouple for reducing atmospheres

Thermocouple measures continuously in flowing gaseous hydrogen at temperatures up to 4000 deg F, in environments made hazardous by radiation, and where rapid response and calibration reproducibility are critically important. Thermocouple wires extend continuously, without splice or foreign material, from cold junction to probe's tip

Acroneuria lycorias (Boreal Stonefly, Plecoptera: Perlidae) Emergence Behaviors Discovered in Pinus strobus Canopy

Species of Plecoptera, or stoneflies, are known to use vertical emergence supports, and researchers believe many species of Plecoptera exploit arboreal habitats during emergence. However, the exact nature of these arboreal behaviors has largely remained a mystery. While exploring the habitat potential of Pinus strobus (L.) (Eastern White Pine) canopies in northern Wisconsin we observed Acroneuria lycorias (Newman) (Boreal Stonefly, Plecoptera: Perlidae) exuviae at heights as high as 12m (observations at 6.6, 9, 9.5, and 12m). Most A. lycorias exuviae appeared to have a strong preference for emergence sites at the underside or base of branches similar to some Odonate species. We also observed A. lycorias, adults climbing upwards along the main stem, post-emergence, to heights up to 22m. To our knowledge, these heights represent the greatest heights ever documented for A. lycorias adults and exuviae, or any Plecopteran species. While other researchers have speculated that A. lycorias uses arboreal habitats during emergence, these behaviors were considered almost impossible to describe. Our observations provide us with new insights into Plecopteran emergence behaviors, especially for this species. We propose three alternative hypotheses that may explain these unique emergence behaviors

Transfer of Sulfur from IscS to IscU during Fe/S Cluster Assembly

The cysteine desulfurase enzymes NifS and IscS provide sulfur for the biosynthesis of Fe/S proteins. NifU and IscU have been proposed to serve as template or scaffold proteins in the initial Fe/S cluster assembly events, but the mechanism of sulfur transfer from NifS or IscS to NifU or IscU has not been elucidated. We have employed [35S]cysteine radiotracer studies to monitor sulfur transfer between IscS and IscU from Escherichia coli and have used direct binding measurements to investigate interactions between the proteins. IscS catalyzed transfer of 35S from [35S]cysteine to IscU in the absence of additional thiol reagents, suggesting that transfer can occur directly and without involvement of an intermediate carrier. Surface plasmon resonance studies and isothermal titration calorimetry measurements further revealed that IscU binds to IscS with high affinity (Kd ~2 µM) in support of a direct transfer mechanism. Transfer was inhibited by treatment of IscU with iodoacetamide, and 35S was released by reducing reagents, suggesting that transfer of persulfide sulfur occurs to cysteinyl groups of IscU. A deletion mutant of IscS lacking C-terminal residues 376-413 (IscSDelta 376-413) displayed cysteine desulfurase activity similar to the full-length protein but exhibited lower binding affinity for IscU, decreased ability to transfer 35S to IscU, and reduced activity in assays of Fe/S cluster assembly on IscU. The findings with IscSDelta 376-413 provide additional support for a mechanism of sulfur transfer involving a direct interaction between IscS and IscU and suggest that the C-terminal region of IscS may be important for binding IscU

Comparative biology and population dynamics of searobins (genus Prionotus) with emphasis on populations in the northwestern Gulf of Mexico

Eight species of Prionotus, collected from 5-100 m in the Gulf of Mexico along a cross-shelf transect off Freeport, Tx during October 1977-August 1981, were studied to determine life history patterns and how they partition resources. Only four species were abundant: P. tribulus, P. paralatus, P. longispinosus, and P. stearnsi. Prionotus spp. mature at 80 mm (P. stearnsi and P. rubio), 85 mm (P. tribulus and P. paralatus), 100 mm (P. ophryas), 105 mm (P. roseus), and 120 mm (P. longispinosus). Sizes at Age 1 were 99-140 mm (P. tribulus), 99-138 mm (P. longispinosus), 98-122 mm (P. paralatus), 75-125 mm (P. stearnsi), and 95-129 mm (P. ophryas). Most fish were less than 200 mm. Typical maximum sizes were 155-175 mm (P. tribulus), 145-160 mm (P. longispinosus), 160-165 mm (P. paralatus), 180-195 mm (P. rubio), 125 mm (P. stearnsi), and 155-160 mm (P. ophryas). Fish were typically 1-3 years old at these typical maximum sizes, and most were Age 1 and less. Apparent total annual mortality rates were 80-100%. The eight species fit into three categories based on their bathymetric distributions and community memberships: (1) members of the inshore white shrimp community which occurs from 5 m to about 16 m (P. tribulus); (2) members of the offshore brown shrimp community which occurs from about 36 to at least 100 m (P. paralatus, P. stearnsi, and P. roseus); and (3) members of a transition fauna which occurs between the outer edge of the white shrimp community and the inshore edge of the brown shrimp community from about 18-27 m (P. longispinosus, P. rubio, P. ophryas, and P. scitulus). Comparisons among species indicate a common pattern of population dynamics that favors r-strategy (short life spans, high mortality rates, and rapid turnover of biomass), but with temporally segregated spawning and spatially segregated distributions. Spawning grounds seem to lie toward the northcentral Gulf with current transport mechanisms carrying young toward the northwestern Gulf. Prionotus spp. from the northwestern Gulf show quite different life history attributes than their congeners from mid Atlantic and New England regions