scholarly journals University of Washington Dates IV

Radiocarbon ◽  
1976 ◽  
Vol 18 (2) ◽  
pp. 221-239 ◽  
Author(s):  
A W Fairhall ◽  
A W Young ◽  
J L Erickson
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Counting Rate ◽  
Sea Water ◽  
Differential Pressure ◽  
Dead Volume ◽  
Active Volume ◽  
The Third ◽  
Proportional Counters ◽  
Anticoincidence Counting

The dates reported in this list are for geologic and archaeologic samples only. During the interval since our last date list (R, 1966, v 8, p 498-506) most of our measurements have been on samples of sea water. These will be reported separately at a later time. The methods used are essentially those reported previously (R, 1963, v 5, p 80-81) but with the following notable changes and additions: We now prepare our methane counting gas as described in Buddemeier et al (1970). Our IL membrane counter has since been augmented by 3 additional counters. Two of these are IL quartz proportional counters inside geiger anticoincidence shields. Operating pressures are ca 1.5 to 4atm. Backgrounds of these 2 counters are in the neighborhood of 1.8 and 3cpm and the net counting rate of NBS oxalic acid ranges from 7 to 18.7cpm, depending on the pressure. The third counter (“minicounter”) is rather special: .IL quartz proportional counter inside a methane proportional anticoincidence counter. Sample and anticoincidence counting gases are introduced simultaneously with a differential pressure that never exceeds a few cm Hg. The sample filling side is constructed so as to minimize dead volume; over 80% of the sample gas is inside the active volume of the 14C counter. The range of filling pressures which are possible is ca 1 to 4atm.

scholarly journals Stockholm Natural Radiocarbon Measurements IV

Radiocarbon ◽  
1962 ◽  
Vol 4 ◽  
pp. 115-136 ◽  
Author(s):  
Lars G. Engstrand ◽  
H. Göte Östlund
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Half Life ◽  
The Third ◽  
Direct Continuation

This paper is a direct continuation of the third dating list (Stockholm III), and the entire technique is virtually unchanged, using one 0.5–1 and one 1.0.1 3 atm CO2proportional counter. Ages are calculated according to the recommendation given in the introduction of this book, and δC13has been measured for unknown samples and for the different CO2preparations of the NBS oxalic-acid standard. Since the numerical relationship between the C14activity of our old oak standard and that of NBS was valid for a δC13value of almost exactly −19 for the NBS preparation in question, it still holds true that all dates given in Stockholm I, II and III can be converted to the new scale by subtracting 55 yr. The NBS preparation St-532 measured by Craig (1961) having a δC13value of −17.2 is only one of several preparations with values between −17 and −20. Age figures are given in C14yr before A.D. 1950; the half life for C14is taken as 5568 ± 30 yr.

scholarly journals Gliwice Radiocarbon Dates IV

Radiocarbon ◽  
1978 ◽  
Vol 20 (3) ◽  
pp. 405-415 ◽  
Author(s):  
Wlodzimierz Moscicki ◽  
Anna Pazdur ◽  
Mieczyslaw F Pazdur ◽  
Andrzej Zastawny
Keyword(s):  
Carbon Dioxide ◽  
Oxalic Acid ◽  
Counting Rate ◽  
Radiocarbon Dates ◽  
Proportional Counters

All samples described in this date list have been measured since July 1973 to Oct 1975 using carbon dioxide filled proportional counters. Most of samples have been dated with Counter No. 1 (LI) as in our previous list (Mościcki and Zastawny, 1976). Some samples were measured with Counter No. 3 (L3), with a total volume of 1.51 and background and NBS oxalic acid standard counting rate of respectively, 3.50 or 4.00 cpm and 10.05 or 20.40 cpm when filled to 1 or 2 atm pressure (Mościcki and Zastawny, 1977).

scholarly journals Bratislava Radiocarbon Measurements II

Radiocarbon ◽  
1977 ◽  
Vol 19 (3) ◽  
pp. 389-391
Author(s):  
S Usačev ◽  
J Chrapan ◽  
J Oravec ◽  
B Sitár
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Half Life ◽  
Nuclear Physics ◽  
Radiocarbon Dating ◽  
Initial Conditions ◽  
Sample Pretreatment ◽  
Active Volume ◽  
Statistical Errors ◽  
Sample Count

Radiocarbon dating facilities were built at the Department of Nuclear Physics, Comenius University in 1967 (Usačev et al, 1973). Initially, sample pretreatment and combustion systems for a proportional counter filled with CO2 were installed (Chrapan, 1966). One group adopted methods based on the use of methane (Usačev et al, 1973), a second group continued radiocarbon dating using an Oeschger-type proportional counter filled with CO2 (Chrapan, 1968). Later a modified Oeschger-type proportional counter with 1L active volume and with a background of approximately 8.10–2 bq was built (Schmidt and Chrapan, 1970). The pressure used in this counter is 105 Pa. 0.95 NBS oxalic acid is used as a standard of the present biosphere and the year 1950 refers to the zero year. Calculated radiocarbon ages are based on a 5568 ± 30 year half-life as recommended by the 8th International Radiocarbon Dating Conference. Statistical errors are calculated as a combination of the 3σ standard deviations of the sample count and the background. Samples were treated by HCl, NaOH or other chemicals according to their initial conditions.

scholarly journals Gliwice Radiocarbon Dates VII

Radiocarbon ◽  
1982 ◽  
Vol 24 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Anna Pazdur ◽  
Romuald Awsiuk ◽  
Andrzej Bluszcz ◽  
Mieczysław F Pazdur ◽  
Adam Walanus ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Oxalic Acid ◽  
Integrated Circuit ◽  
Proportional Counter ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Unknown Sample ◽  
Proportional Counters ◽  
Typical Measurement ◽  
Contemporary Standard

The following list contains the measurements of archaeologic samples made during 1978 and 1979 using carbon-dioxide-filled proportional counters. Most of the samples were dated with counter No. 3 (L3) filled to 1 or 2 atm pressure (Mościcki and Zastawny, 1977). Our counter No. 1 (L1) previously described (Mościcki and Zastawny, 1976) has been remounted and is now operating at 2 atm pressure of carbon dioxide. Samples measured with this counter have date numbers starting with Gd-1000. Parameters of proportional counters are listed in Table 1. Our transistorized electronics is being gradually replaced by more compact integrated-circuit electronics in CAMAC system (Bluszcz and Walanus, 1980). Counts from proportional counter and guard counters are recorded in 5 channels and punched every 100 minutes. Typical measurement of any sample, including background and oxalic acid samples, consists of a series of 20 to 25 partial measurements. Partial results obtained in such series are analyzed on ODRA 1325 computer at the Computing Centre of the Silesian Technical University according to code C14C written in ALGOL (Pazdur and Walanus, 1979). Age calculations are based on contemporary value equal to 0.95 of the activity of NBS oxalic acid standard and on the Libby value for the half-life of radiocarbon. Ages are reported as conventional radiocarbon dates in years before ad 1950. Corrections for isotopic fractionation in nature are made only for some samples with indicated values of δ13C Errors quoted (±1σ) include estimated overall standard deviations of count rates of the unknown sample, contemporary standard, and background (Pazdur and Walanus, 1979).

scholarly journals National Taiwan University Radiocarbon Measurements I

Radiocarbon ◽  
1970 ◽  
Vol 12 (1) ◽  
pp. 187-192 ◽  
Author(s):  
Yuin-Chi Hsu ◽  
Chia-Yi Huang ◽  
Shih-Chong Lu
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Counting Rate ◽  
Room Temperature

Natural C14 measurements have been performed at the Dept. of Physics, National Taiwan University since 1965, using a cylindrical proportional counter of 1000 ml (Hsu et al., 1965). The proportional counter is operated with CO2 as the filling gas at a pressure of 1216 mm Hg at room temperature of 20°C. Working voltage is 4.7 Kv, with a plateau length of more than 700 v and a plateau slope of ca. 1% per 100 v. Background is reduced to 5.1 counts/min and the counting rate of the NBS oxalic acid standard is 9.4 counts/min at the normal counting pressure of 1216 mm Hg.

scholarly journals University of Tokyo Radiocarbon Measurements III

Radiocarbon ◽  
1971 ◽  
Vol 13 (1) ◽  
pp. 94-96 ◽  
Author(s):  
Jun Sato ◽  
Tomoko Sato ◽  
Yasuko Matsui ◽  
Hisashi Suzuki
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Half Life ◽  
Counting Rate ◽  
Modern Standard

Radiocarbon measurements in this list were made from Sept. to Dec., 1968. They are based on acetylene counting in an Oeschger-Houtermans-type proportional counter (1 L) at pressure 1 atm. All data are based on duplicated measurements. For calculation of ages, 95% activity of NBS oxalic acid is used as the modern standard and value of 5570 + 30 years is used for the half-life of C14. Dates are expressed in years B.P. (before A.D. 1950). Error corresponds to 1σ deviation of sample net counting rate as well as modern standard and background. Details of procedures are given in previous reports (R., 1968, v. 10, p. 144–148; 1969, v. 11, p. 509–514)

Reosquido Desalinasi Metode Evaporasi dengan Ultraviolet Berbasis Mikrokontroller

2018 ◽  
Vol 3 (2) ◽  
pp. 38-47
Author(s):  
Muhammad Abdul Azis ◽  
Nuryake Fajaryati
Keyword(s):  
Temperature Measurement ◽  
Fresh Water ◽  
Sea Water ◽  
Evaporation Process ◽  
Heater Element ◽  
The Third ◽  
Turn On ◽  
Speed Up ◽  
Arduino Uno

This research aims to create a Reosquido desalination tool for evaporation methods using a microcontroller. This tool can control the temperature to speed up the evaporation process in producing fresh water. The method applied to Reosquido desalination uses Evaporation. The first process before evaporation is the detection of temperature in sea water that will be heated using an element heater. The second process of temperature measurement is to turn off and turn on the Arduino Uno controlled heater, when the temperature is less than 80 ° then the heater is on. The third process is evaporation during temperatures between 80 ° to 100 °, evaporation water sticks to the glass roof which is designed by pyramid. Evaporated water that flows into the reservoir is detected by its solubility TDS value. The fourth process is heater off when the temperature is more than 100 °. Based on the results of the testing, the desalination process using a microcontroller controlled heater can speed up the time up to 55% of the previous desalination process tool, namely manual desalination prsoes without using the heater element controlled by the temperature and controlled by a microcontroller which takes 9 hours. Produces fresh water as much as 30ml from 3000ml of sea water, so that it can be compared to 1: 100.

GAS–LIQUID CHROMATOGRAPHY OF TERPENES: PART II. THE DEHYDRATION PRODUCTS OF α-TERPINEOL

1961 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
E. Von Rudloff
Keyword(s):  
Liquid Chromatography ◽  
Oxalic Acid ◽  
Complex Mixture ◽  
Reaction Times ◽  
Gas Liquid Chromatography ◽  
Minor Components ◽  
Reaction Products ◽  
The Third ◽  
Major Reaction ◽  
Trace Constituents

The complex mixture of terpenes obtained on dehydrating α-terpineol with aqueous oxalic acid was almost completely separated by gas–liquid chromatography (GLC), using rapeseed oil as a new liquid phase. Terpinolene, dipentene, α- and γ-terpinene, Δ2,4(8)-p-menthadiene, and 1,8-cineole were identified as the major reaction products; three minor and seven trace constituents were also detected. One of the minor components was p-cymene, one an oxide, and the third an unidentified hydrocarbon. The yield of these components after different reaction times was determined by GLC. The initial dehydration gives terpinolene and dipentene in the ratio of approximately 2:1. Terpinolene is isomerized to α- and γ-terpinene, Δ2,4,(8)-p-menthadiene, and the unidentified hydrocarbon, but not to dipentene. 1,8-Cineole and the other oxide are formed in a reversible reaction. Dehydration of α-terpineol with several other acidic reagents yielded mixtures of products similar to that obtained with aqueous oxalic acid. With acetic acid or acetic anhydride, however, dipentene was formed preferentially and this reaction appears to proceed via the derived acetate.

scholarly journals Physical Research Laboratory Radiocarbon Date List VI

Radiocarbon ◽  
1991 ◽  
Vol 33 (3) ◽  
pp. 329-344 ◽  
Author(s):  
D. P. Agrawal ◽  
Sheela Kusumgar ◽  
M. G. Yadava
Keyword(s):  
Standard Deviation ◽  
Oxalic Acid ◽  
Proportional Counter ◽  
Research Laboratory ◽  
Radiocarbon Date ◽  
Geological Samples ◽  
Physical Research Laboratory ◽  
Detailed Procedure ◽  
Counting Statistics ◽  
Modern Standard

We present here dates for archaeological and geological samples. The dates are based on τ1/2 = 5568 years, using 1950 as the base year. The modern standard was 95% of activity of NBS oxalic acid.Samples were pretreated, prepared by methane synthesis and counted in a proportional counter. The detailed procedure has been described earlier (Agrawal, Gupta & Kusumgar 1971). We reported minor changes in previous date lists. Quoted errors are based on counting statistics alone. For samples younger than 10,000 years, the error is 1 standard deviation, and for older samples, 2 standard deviations. The dates are not corrected for 13C fractionation. Samples have been arranged alphabetically according to the name of the site.

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