Blank Temperature Research Articles

The heating duration and provenance age of rocks in the Salton Sea geothermal field, southern California

40 Ar/ 39 Ar step heating of single K-feldspar crystals (∼ 500 μ g) in a furnace with a low argon blank and accurate temperature control provide constraints on the thermal history of the Salton Sea geothermal field, southern California. Estimates of 40 Ar loss from detrital K-feldspars, coupled with kinetic information gleaned from laboratory degassing of 39 Ar, allow possible thermal histories to be evaluated. Samples from core and cuttings of sandstones from the State 2–14, Landers #1, Dearborn Farms #1, Magmamax #2, Elmore #3 and Sinclair #3 wells have been analyzed for this purpose. No recent 40 Ar ∗ loss is recognized in any of the 17 crystals measured, even for samples currently at temperatures greater than 275°C. This observation suggests that the present temperature distributions in these wells have not been maintained for greater than 1000 years. However, aggregates (∼ 100 mg) of two K-feldspar samples do reveal recent 40 Ar ∗ loss from the State 2–14 well, suggesting a time scale of 1000 to 5000 years for near-peak thermal conditions. These estimates of heating duration are broadly consistent with earlier results from thermal modelling, but do not support interpretations that paleotemperatures were once hotter than present. Provenance ages span the Tertiary through Middle Proterozoic but cluster at ages of 25, 70 and 1250 Ma. These age peaks are very common K-feldspar K-Ar ages in detachment terranes of southeastern California and southwestern Arizona, both drained by the Colorado River. This coincidence supports earlier suggestions that the sands of the Salton Trough were derived mainly from the Colorado River. Unrealistically low apparent activation energies (< 20 kcal/mol) for argon transport are observed for several single crystals which yield absurdly low calculated closure temperatures (e.g., -100°C). We infer that this anomalous behaviour results from a combination of the laboratory heating schedule and the distribution of diffusion domain sizes.

リニアスケール用レーザ干渉刻線機

Described in this paper is a ruling machine for linear scales that is controlled by a laser interferometer with simple and inexpensive electronic systems. A He-Ne two-mode laser is used as a light source of the interferometer, and the stabilization of the wavelength depends on the comparison of the light intensities of the operating longitudinal modes. Fringes produced by the interferometer are changed to a train of electric pulses that measure the displacement of the moving carriage of the interferometer with the unit of one tenth of the wavelength. The pulse train is, after passing through a gate, fed to an electronic counter which operates a flash lamp. At the gate, the periodic elimination of the pulses is done to cancel the accumulation of the errors of the pulse spaces. The interval of elimination is calculated by a computer using the measured values of atmospheric temperature and pressure, and scale blank temperature. The light from the flash lamp is thrown on a slit and the reduced image of the slit is focused on a photographic plate which is mounted on the moving carriage. The accuracy of linear scales of 200mm long made by this ruling machine is found to be better than ±0.3 μm.

Experimental artifacts and determination of accurate Py values

Recently the Py solvent scale has been introduced and a large body of data has been generated using fluorescence measurements. Numerous problems exist in the correct determination of these values, including instrumental and chemical artifacts. Among the instrumental problems associated with correct Py assignments are slit width effects, inner filtering and efficiencies associated with double-pass vs. single-pass cell compartment designs. These instrumental problems, together with chemical artifacts related to adequate blank correction and temperature control, were investigated in the work reported in this paper.

Warm and Cold Heading of Stainless Steel

A series of warm and cold heading tests ranging from room temperature to 400 deg C have been conducted on 305 and copper bearing 302 stainless steel wires as well as 0.2 percent C steel wire using a fully instrumented double blow Waterbury-Farrel machine heading 100 blanks per minute. Total and frictional forces developed during the first blow using a variety of lubricants, together with the second blow loads have been recorded. The effectiveness of the different lubricants employed was examined. The optimum blank temperature for warm heading stainless steel is in the range 200 to 400 deg C where the punch loads are reduced about 25/30 percent, compared to cold heading. Within this temperature range the friction coefficient for the copper coated stainless steel possessing a stearate film on the surface remains relatively low (μ ∼ 0.01/0.02). Reduced punch loads are shown to effect an increase in punch life. For all temperatures the heading loads for the copper bearing 302 stainless steel were lower than for 305 stainless steel. Both these materials exhibit a weak dynamic strain aging effect compared with plain carbon steel. In fact the heading loads were higher between 300 deg and 400 deg C for the plain carbon steel. At room temperature components made from both copper bearing 302 stainless steel and 305 stainless steel possessed fewer shear cracks when employing the former material and this effect is attributed to a lower strain hardening rate.

THE EFFECT OF SELECTED PLATING PROCEDURES ON THE BACTERIAL COUNT OF INSTANT NONFAT DRY MILK

SummaryIt was estimated that the addition of 10.5g of instant non-fat dry milk to 99 ml of water more nearly approximated a 1:10 dilution than did the currently recommended addition of 11 g of powder. It was estimated that the addition of a gram of powder to 99 ml of water increased the volume 0.5798 ml. Incubation of plates for 3 days produced counts 71% higher than those obtained using 2 days incubation. The use of dilution blanks tempered at 45 C resulted in a 27% increase over the count obtained using dilution blanks at room temperature. The interaction between incubation time and water blank temperature indicated that the warmed dilution blanks exerted a stimulatory effect upon the microorganisms in the powder. Counts obtained using overlayed plates could be more accurately replicated but non-overlayed plates yielded counts 15% greater. The use of Standard Methods Agar produced counts 10% higher than those obtained using Milk Protein Hydrolysate Agar. Shaking dilution bottles 50 times produced counts no larger than those obtained by shaking the bottles 25 times. A pooled estimate of the variance between duplicate plates was found to be 0.0087.