An electrically calibrated bomb calorimeter

1955 ◽  
Vol 247 (936) ◽  
pp. 553-582 ◽  
Keyword(s):  
Benzoic Acid ◽  
Outer Surface ◽  
Standard Error ◽  
Heat Of Combustion ◽  
Bomb Calorimetry ◽  
Bomb Calorimeter ◽  
Effective Boundary ◽  
The Difference

After a review of the physical foundations of bomb calorimetry, a bomb calorimeter is described which can be heated electrically or by combustion. The evaporation of water is prevented by sealing the vessel completely. Other modifications in the normal technique are introduced after consideration of ( a ) the difference in temperature between the outer surface of the calorimeter and the thermometer immersed in it, ( b ) the effective ‘boundary’ of the calorimeter in electrical and combustion experiments, and ( c )variation with temperature of the constants of the apparatus. The heat of combustion of samples from a batch of thermochemical quality benzoic acid is found to be 26436 J/g under ‘standard bomb conditions’. The standard error of the determination, a combination of errors in reproducibility of electrical and combustion experiments and in measurement of the corrections, is estimated to be 2.2 J/g.

Aneroid bomb calorimeter for determining the heat of combustion of thermochemical standard benzoic acid

1960 ◽  
Vol 256 (1286) ◽  
pp. 384-399 ◽  
Keyword(s):  
Benzoic Acid ◽  
Standard Error ◽  
Heat Of Combustion ◽  
Bomb Calorimeter ◽  
The Ideal

An electrically calibrated bomb calorimeter is described which has no stirred water, and is mounted in an evacuated outer jacket. Its departures from the ideal are investigated. The heat of combustion of samples from a batch of specially pure benzoic acid is found to be 26431·7 J/g under ‘standard bomb conditions’, with an estimated standard error of 2·2 J/g. This result is compared with those of conventional calorimeters. Considerably less time per determination is needed with the new calorimeter than with a typical conventional calorimeter.

scholarly journals Comparison of organics and heavy metals acute toxicities to Vibrio fischeri

2016 ◽  
Vol 81 (6) ◽  
pp. 697-705 ◽  
Author(s):  
Xuepeng Yang ◽  
Yan Ji ◽  
Fangfang Wang ◽  
Jia Xu ◽  
Xiangzhen Liu ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Cell Death ◽  
Benzoic Acid ◽  
Death Rate ◽  
Vibrio Fischeri ◽  
Reaction Times ◽  
Inhibition Rate ◽  
Cell Death Rate ◽  
Bioluminescence Inhibition ◽  
The Difference

Vibrio fischeri bioluminescence inhibition has been widely used to test acute toxicities of metals and organics contaminants. However, the differences of metals and organics acute toxicities to V. fischeri have not been compared. Here, four heavy metals (Zn2+, Cu2+, Cd2+, Cr6+) and five organics (phenol, benzoic acid, p-hydroxy benzoic acid, nitro-benzene and benzene) acute toxicities to V. fischeri were investigated. Heavy metals toxicities to V. fischeri were increased along with the reaction time, while the organics toxicities kept the same level in different reaction times. In order to explain the difference, the relative cell death rate of V. fischeri was detected. In metals toxicities tests, the bioluminescence inhibition rate of V. fischeri was found to be significantly higher than the relative cell death rate (P<0.05), while for the organics toxicities tests, the cell death rate was similar to the bioluminescence inhibition rate. These results indicated that organics acute toxicities to V. fischeri could reflect the death of cell, but metals acute toxicities to V. fischeri may not lead to the death of cell, just represent the bioluminescence inhibition.

scholarly journals National Physical Laboratory Radiocarbon Measurements IV

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 340-347 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
Geraldine I. Hassall
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Count Rate ◽  
National Physical Laboratory ◽  
Background Count ◽  
Best Value ◽  
Sample Count ◽  
The Difference ◽  
Absolute Age

The following list comprises measurements made since those reported in NPL III and is complete to the end of November 1965.Ages are relative to A.D. 1950 and are calculated using a half-life of 5568 yr. The measurements, corrected for fractionation (quoted δC13 values are relative to the P.D.B. standard), are referred to 0.950 times the activity of the NBS oxalic acid as contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances as described in detail in NPL III. These variances are those of the standard and background measurements over a rolling twenty week period, of the sample δC14 and δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty then included. If the net sample count rate is less than 4 times the standard error of the difference between the sample and background count rates, a lower limit to the age is reported corresponding to a net sample count rate of 4 times the standard error of this difference.

scholarly journals National Physical Laboratory Radiocarbon Measurements II

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 25-30 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
Daphne H. Pritchard
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Research Programme ◽  
National Physical Laboratory ◽  
Reference Standard ◽  
Best Value ◽  
Physical Laboratory ◽  
The Difference ◽  
Absolute Age

The following list comprises measurements made since those reported in NPL I and is complete to the end of November 1963.Ages are relative to a.d. 1950 and are calculated using a half-life of 5568 yr. The measurements have been corrected for fractionation and referred to 0.950 times the activity of the NBS oxalic acid as a contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances, viz. those of the standard and background measurements over a rolling twenty-week period, of the sample measurements from at least three independent fillings, of the δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty included. If the net sample activity is less than 4 times the standard error of the difference between the sample and background activities, a lower limit to the age is reported equivalent to a sample activity of 4 times the standard error of this difference.The description of each sample is based on information provided by the person submitting the sample to the Laboratory.The work reported forms part of the research programme of the Laboratory and is published by permission of the Director.

COMPARISONS OF MILKFAT TESTS ON COMMERCIAL MILK SAMPLES DETERMINED BY THE MILKO-TESTER AND BABCOCK METHODS1

1969 ◽  
Vol 32 (6) ◽  
pp. 203-205 ◽  
Author(s):  
Roy E. Ginn ◽  
Vernal S. Packard
Keyword(s):  
Standard Error ◽  
Milk Samples ◽  
Fresh Milk ◽  
Dairy Plant ◽  
The Mean ◽  
Commercial Milk ◽  
The Difference ◽  
Composite Samples

Milk samples were collected daily from 47 producers shipping manufacturing grade milk in cans to a single dairy plant over a 31-day period. Samples were transported to the laboratory where, 24 hr later, a portion of each sample was composited, and Milko-tester and Babcock milkfat determinations made on the remainder of the sample. At the end of one 15-day and one 16-day composite period, the composite samples were tested using both procedures. The data thus collected was placed on computer cards and analyzed statistically. The Milko-tester calibrated on “fresh” milk was found to average 0.059% lower on composite than on fresh samples. For fresh milk and composite samples, respectively, the standard error of the paired methods was 0.0482 and 0.0370, and the standard error of the difference of the mean was 0.0122 and 0.0262. These values for the 4-day random stratified samples were 0.0444 and 0.0222, respectively. On 1,457 fresh milk samples the average Milko-tester and Babcock results were, respectively, 3.788 and 3.809%; the difference being 0.0211%. The average test on 188 composite samples by the two methods was 3.8192 and 3.7979% respectively, or a difference of 0.0213%

Machine effects on accuracy of ultrasonic prediction of backfat and ribeye area in beef bulls, steers and heifers

2000 ◽  
Vol 80 (1) ◽  
pp. 19-24 ◽  
Author(s):  
P. K. Charagu ◽  
D. H. Crews Jr. ◽  
R. A. Kemp ◽  
P. B. Mwansa
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Standard Error ◽  
Important Relationship ◽  
Ribeye Area ◽  
Beef Bulls ◽  
The Difference

Pre-slaughter ultrasound and carcass measurements of ribeye area (REA) and backfat (FAT) were recorded on composite beef bulls (n = 60), heifers (n = 60) and steers (n = 60). Breed composition of the composite was: 0.44 British (Hereford, Angus and Shorthorn) 0.25 Charolais, 0.25 Simmental and 0.06 Limousin. The Aloka SSD-1100 (AL) and the Tokyo Keiki CS 3000 (TK) ultrasound machines were compared by evaluating the difference between ultrasound and carcass measurements (bias), and the standard error of prediction (SEP). AL under-predicted REA in all three sexes while TK overpredicted heifers and steers and underpredicted bulls. Both machines were similar in accuracy among bulls for REA. For FAT AL underpredicted all three sexes while TK underpredicted heifers and had very small bias for bulls and steers. SEP for FAT were similar for both machines. Both machines underpredicted REA in larger muscled cattle and overpredicted in smaller-muscled cattle. Both machines also underpredicted FAT in fatter animals and overpredicted FAT in leaner animals. Machines were similar in accuracy among cattle with larger REA but differed significantly (P < 0.05) among smaller-muscled cattle. Machines were comparable in accuracy among animals of all FAT sizes. This study demonstrates that there is an important relationship between machine and the size and depth of muscle and backfat, respectively, and consequently between machine and sex, in accuracy of ultrasound prediction. Key words: Beef cattle, ultrasound, accuracy, back fat, ribeye area

Determination of the Age of Swiss Lake Dwellings as an Example of Dendrochronologically-Calibrated Radiocarbon Dating

1966 ◽  
Vol 21 (7) ◽  
pp. 1173-1177 ◽  
Author(s):  
C. W. Ferguson ◽  
B. huber ◽  
H. E. Suess
Keyword(s):  
Tree Ring ◽  
Standard Error ◽  
Radiocarbon Dating ◽  
Tree Ring Chronology ◽  
Radiocarbon Dates ◽  
Pine Wood ◽  
Bristlecone Pine ◽  
The Difference ◽  
Swiss Lake

Comparison of the radiocarbon content of a series of samples of dendrochronologically dated bristlecone pine wood with that from trees for which a so-called floating tree-ring chronology has been established makes it possible to determine an empirical age for this floating tree-ring series based upon the age of the wood used for comparison. For the case of the Swiss Lake Dwellers, the difference between conventional radiocarbon dates and the age values determined in this manner amounts to about 800 years. The age of the floating chronology was determined within a standard error of less than 40 years. The measurements indicate that the dwellings were constructed during the 38th century B. C.

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