Determination of Resistance to Abrasive Wear. X. Investigation of the Durability of a Bonded Abrasive Wheel on the Du Pont Machine

1949 ◽  
Vol 22 (1) ◽  
pp. 264-268 ◽  
Author(s):  
R. G. Newton ◽  
J. R. Scott
Keyword(s):  
Abrasive Wear ◽  
Test Results ◽  
Volume Loss ◽  
Abrasive Wheel ◽  
Abrasive Particles ◽  
Significant Difference ◽  
Statistical Planning ◽  
The Mean ◽  
Test Result

Abstract The results reported here entirely confirm those of Lambourn, who found that marked deterioration occurred with all the types of abrasive wheel which he used. In the present investigation on a bonded wheel, it was concluded that the wheel was appreciably less abrasive after each period of. 50 hours' wear, while Lambourn concluded that one side of a wheel can be used for a period of two months when subjected to 40 hours of wear per week. Lambourn also concluded that the deterioration is caused by smoothing or disintegration of the abrasive particles and not by clogging with rubber dust, and points out that variation in abrasive wear can be compensated by daily tests on samples of a standard compound. He also states that a grain coarser than 24 should not be used, since the abrasion is too rapid. Since the standard emery papers vary among themselves, and the bonded abrasive wheel deteriorates when it is used, it is evident that attention should be paid to the statistical planning of these tests, so that these factors can be reduced or eliminated. The coefficient of variation of a test result, i.e., the mean of three 10-minute runs, each on duplicate specimens, (six individual readings) as normally measured, seems to be independent of the type of abrasive employed (emery papers or bonded disc) and the uncertainty of the result is about ±5 per cent when measured on the basis of volume loss per hour and about ±3.5 per cent when determined as the volume loss/H.P.-hr. Test results will therefore be required to differ by about 7 and about 5 per cent, respectively, for a significant difference to be demonstrated.

scholarly journals Investigation of the unfused cross cylinder test as an alternative method for the determination of spherical distance refraction end points

2020 ◽  
Vol 79 (1) ◽  
Author(s):  
Nkalebetja T. Makgaba ◽  
Solani D. Mathebula
Keyword(s):  
Adult Population ◽  
Test Results ◽  
End Points ◽  
Room Illumination ◽  
End Point ◽  
Cylinder Test ◽  
Significant Difference ◽  
Young Adult Population ◽  
The Mean

Background: The duochrome test is commonly used to refine the final sphere in refraction at different stages of a subjective refraction. The unfused cross cylinder test is mainly used to determine the near reading addition with a combination of astigmatic lenses.Aim: To investigate if the unfused cross cylinder test can be adapted for distance in finding the spherical end point for distance prescription.Setting: The study was conducted at an Optometry Clinic, University of Limpopo, South Africa.Methods: Fifty-one non-presbyopic subjects aged between 18 and 25 years were examined. The duochrome and unfused cross cylinder examinations were performed monocularly under normal (bright) and dim room illumination.Results: There was no significant difference in the spherical end point determined with either the duochrome or unfused cross cylinder tests (p ≥ 0.05). The mean spherical end points as determined with the duochrome test were −0.09 ± 0.39 diopre sphere (DS) (range: −0.20 to 0.12 dioptres [D]) in bright room illumination and −0.05 ± 0.38 DS (range: −0.16 D to 0.05 D) in dim illumination. The mean spherical end points for the unfused cross cylinder tests were −0.29 ± 0.39 DS (range: −0.18 D to 0.40 D) and −0.32 ± 0.43 DS (range: –0.44 D to –0.19 D) in room dim illuminations, respectively.Conclusion: The unfused cross cylinder test results as performed in this study may provide an accurate measurement of the spherical end point in a young adult population. We recommend the unfused cross cylinder test to be used in normal (bright) room illumination as an alternative to the duochrome test in the determination of distance refractive error.

scholarly journals Anthropogenetic variability in the groups of homo- and heterosexually oriented individuals

Genetika ◽  
2015 ◽  
Vol 47 (2) ◽  
pp. 765-776
Author(s):  
Suzana Cvjeticanin
Keyword(s):  
Genetic Variability ◽  
Population Genetic ◽  
Control Group ◽  
Population Genetic Study ◽  
Test Results ◽  
Mean Values ◽  
Significant Difference ◽  
The Mean ◽  
Distribution Type

This population-genetic study compares morphophysiological and genetic variability in a group of homosexually oriented individuals from Serbia (N=96) with control group of heterosexual individuals (N=96) using a test of determination of homozygously recessive characteristics in humans (HRC-test). Results of our study revealed a statistically significant difference in the mean values of genetic homozygosity (control group 5.0+0.2 ; homosexuals 3.4 +0.1 HRCs, out of 20 observed characteristics) the differences in the distribution type, as well as in the variances of presence of specific combinations of such traits. These results suggest a complex polygenic difference between two observed systems. There is no difference in the degree of genetic homozygosity between the genders in each tested group of individuals. However, both homosexually oriented females and males have significantly lower mean values of HRCs compared to female and male heterosexuals.

150 USING A LUTEINIZING HORMONE SURGE DETECTION TEST, PREDI'BOV®, TO OPTIMIZE THE TIME OF ARTIFICIAL INSEMINATION DURING A SUPEROVULATION PROTOCOL IN A HOLSTEIN HEIFERS HERD

2015 ◽  
Vol 27 (1) ◽  
pp. 166
Author(s):  
H. Quinton ◽  
F. Charreaux ◽  
A. Morel ◽  
A. Rohou ◽  
L. Dupuy ◽  
...  
Keyword(s):  
Preliminary Test ◽  
Test Results ◽  
Embryo Viability ◽  
Lh Surge ◽  
Activity Peak ◽  
Significant Difference ◽  
Group A ◽  
The Mean ◽  
Luteinizing Hormone Surge ◽  
Test Result

Insemination of superovulated bovine donors in due time is of central importance for fertilization and embryo viability. A preliminary test focusing on LH surge detection during superovulation (unpublished datas) indicated that one quarter of the donors present LH surges 12 to 24 h before heat observation (which could correspond, in the case of AI after heat observation, to post ovulation AI). Therefore, it was hypothesised that the average number of embryos per flush could be improved by inseminating donors with early LH surge 12 h after the beginning of the LH peak whenever the heat occurs.In a donor herd station, a trial was performed with 54 Holstein heifers, equipped with Heatime® tags (system detecting the peak activity linked to the heat) collected twice or 3 times after the following superovulation protocol: D-6 to D-11 = reference heat; D0 = input of an implant of norgestomet (Crestar®); D2 8:00 = first FSH (Stimufol®) injection (FSH1); D4 8:00 = cloprostenol (Estrumate®) injection; D4 16:00 = implant removal; D5 8:00 = FSH7 and first LH surge detection test (Predi'Bov®); D5 16:00 = FSH8 and 2nd Predi'Bov® test. Two AI's at interval of 8 to 16h were done (AI's were performed either at 9:00, or between 17:00 and 19:00). For the standard protocol (= STA), thefirst AI occurred after heat observation or activity peak detection by Heatime (whatever the Predi'Bov® test results were). For the adjusted protocol (= ADJ), the first AI occurred from 11 to 16 h after the first positive Predi'Bov® test result or like STA protocol if both results were negative. Heifers followed alternately the 2 protocols, 27 beginning with the ADJ protocol, 27 others with the STA one. LH surge precocity was not repeatable among donors. In the case of an early LH surge detection (one positive Predi'Bov® test), the heat activity peak occurred from 2 to 8 h after the FSH8 for 44% of the flushes, from 8 to 24 h after FSH8 for 54% of the flushes and never for 2% of the flushes. When no early LH surge was observed, the heat activity peak occurred more than 8 h after FSH8 for 78% of the flushes. Interval of heat activity peak-FSH8, IA1-heat activity peak and IA1-early LH surge were highly variable but did not effect the mean number of viable embryos. However, we observed a significant effect (P = 0.04) of the precocity of the heat on the average number of total embryos: 13.8 ± 8.4 v. 11.1 ± 8.1 when the interval heat activity peak-FSH8 had been respectively <8 h or ≥8 h, respecively. Among the 148 collections, 74 were done after the STA protocol, 74 after the ADJ protocol and 70 followed an early LH surge. The adjustment of the AI depending on the detection of an early LH surge (ADJ protocol) had a significant positive (P = 0.04) effect on the mean percentage of viable embryos per flush (52% ± 28 in STA group and 62% ± 31 in ADJ group). Nevertheless, regarding the mean number of viable embryos, this effect failed to reach significance (P = 0.23) (respectively 5.7 ± 5.1 in STA group and 6.7 ± 6.7 in ADJ group). A larger study on more animals is necessary to obtain a significant difference in the number of viable embryos.

scholarly journals Sex and side determination of human hip bone by metric parameters of its posterior border

2013 ◽  
Vol 02 (01) ◽  
pp. 016-021
Author(s):  
Sarita R Margam ◽  
Megha A Doshi ◽  
Surekha D Jadhav ◽  
Raosaheb J Patil ◽  
Manoj P Ambali
Keyword(s):  
Sex Determination ◽  
Ischial Tuberosity ◽  
Test Results ◽  
Posterior Border ◽  
Bone Material ◽  
Significant Difference ◽  
The Mean ◽  
Two Parameters ◽  
Superior Border

Abstract Background: Identification of sex from skeletal remains is of medico-legal and anthropological importance for forensic experts, anthropologists and anatomists. Hip bone is considered as an ideal bone for sex determination as it provides the highest accuracy levels for sex determination. Aims: To determine the sex and side of the human hip bones by using different metric parameters of posterior border of hip bone. Material and methods: In present study, 200 (100 males and 100 females) dried adult human hip bones of known sex were collected. Two parameters were studied and statistically analysed by paired and unpaired 't' test. Results: In males, distance from the posterior superior iliac spine to the superior border of ischial tuberosity was the discriminant criteria to sex the hip bones while in females, it was distance between the posterior inferior iliac spine (PITS) to ischial tuberosity (IT). Statistically significant difference between the mean related to side were seen in both the variables. Conclusion: These two parameters can be used for sexual dimorphism as well as side determination of human hip bones or its fragments.

Detection of Circulating Tissue Factor and Factor VII in a Normal Population

1996 ◽  
Vol 75 (05) ◽  
pp. 772-777 ◽  
Author(s):  
Sybille Albrecht ◽  
Matthias Kotzsch ◽  
Gabriele Siegert ◽  
Thomas Luther ◽  
Heinz Großmann ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Normal Population ◽  
Mean Value ◽  
Factor Vii ◽  
Significant Difference ◽  
Age Dependent ◽  
The Mean ◽  
Highly Correlated ◽  
And Gender

SummaryThe plasma tissue factor (TF) concentration was correlated to factor VII concentration (FVIIag) and factor VII activity (FVIIc) in 498 healthy volunteers ranging in age from 17 to 64 years. Immunoassays using monoclonal antibodies (mAbs) were developed for the determination of TF and FVIIag in plasma. The mAbs and the test systems were characterized. The mean value of the TF concentration was 172 ± 135 pg/ml. TF showed no age- and gender-related differences. For the total population, FVIIc, determined by a clotting test, was 110 ± 15% and the factor VIlag was 0.77 ± 0.19 μg/ml. FVII activity was significantly increased with age, whereas the concentration demonstrated no correlation to age in this population. FVII concentration is highly correlated with the activity as measured by clotting assay using rabbit thromboplastin. The ratio between FVIIc and FVIIag was not age-dependent, but demonstrated a significant difference between men and women. Between TF and FVII we could not detect a correlation.

scholarly journals Pengaruh Penggunaan Media Gambar Untuk Meningkatkan Hasil Belajar Bahasa Arab Siswa Kelas VII Di Madrasah Tsanawiyah Muhammadiyah 12 Palirangan

2021 ◽  
Vol 7 (1) ◽  
pp. 39-60
Author(s):  
Idzi' Layyinati
Keyword(s):  
Student Learning ◽  
Learning Outcomes ◽  
Human Life ◽  
Student Learning Outcomes ◽  
Arabic Language ◽  
Test Results ◽  
Correlation Test ◽  
Post Test ◽  
The Mean ◽  
Test Result

Education is a necessity for everyone. Educational activities are activities that are very important in human life and cannot be separated from their lives. With education, human needs regarding change and development can be fulfilled. The mean score of the pre-test results was 71.73, while the mean value of the post-test results was 79.61. From these data it can be seen that the pre-test result value is lower than the post-test score, so it can be interpreted that there are differences in student learning outcomes before and after using image media in the learning process. the completeness of the pre-test result value is 46.15%, while the post-test result value is 80.76%. From this data, it can be seen that using image media can affect student learning outcomes. Then from the hypothesis testing using the Product Moment Correlation test and the Paired Sample T-test with the help of SPSS 20 software in the sig (2-tailed) section, it isknown that 0.000 <0.05 The condition is if r count is smaller than r table, then H0 is accepted. and Ha is rejected and vice versa if r count is greater than r table (r count> r table) then H0 is rejected and Ha is accepted. In fact, r count (0.977) is greater than r table (0.404). Thus H0 is rejected and Ha is accepted. As the basis for decision making in the Product Moment Correlation test and decision guidelines based on the probability value, it can be concluded that H0 is rejected and Ha is accepted. This means that image media can affect the improvement of learning outcomes in Arabic language material for class VII at MTs. Muhammadiyah 12Palirangan

Colorimetric Method for Rapid Determination of Serum Arginase

1967 ◽  
Vol 13 (10) ◽  
pp. 900-908 ◽  
Author(s):  
Brigitta Mellerup
Keyword(s):  
Rapid Determination ◽  
Colorimetric Method ◽  
Normal Range ◽  
Clinical Routine ◽  
Mean Values ◽  
Enzymatic Formation ◽  
Significant Difference ◽  
The Mean ◽  
Normal Men

Abstract A method for the determination of serum arginase is given which combines the enzymatic formation of urea with the sensitive method of Coulombe (1) for measuring this substance. This procedure allows more accurate determinations in the normal range than do previous methods described and is convenient for clinical routine. Significant difference is found between the mean values of normal men and women, 3.9 units/L. for the former and 2.9 units/L. for the latter.

Use of Ten Gram Samples of Corn for Determination of Mycotoxins

1988 ◽  
Vol 71 (1) ◽  
pp. 41-43
Author(s):  
Octave J Francis ◽  
George M Ware ◽  
Allen S Carman ◽  
Gary P Kirschenheuter ◽  
Shia S Kuan
Keyword(s):  
Statistical Tests ◽  
Automated System ◽  
Sample Sizes ◽  
Concentration Variance ◽  
Assay Procedure ◽  
Coefficients Of Variation ◽  
The Mean ◽  
Aflatoxin B ◽  
Test Result

Abstract Data were gathered, during a study on the development of an automated system for the extraction, cleanup, and quantitation of mycotoxins in corn, to determine if it was scientifically sound to reduce the analytical sample size. Five, 10, and 25 g test portions were analyzed and statistically compared with 50 g test portions of the same composites for aflatoxin concentration variance. Statistical tests used to determine whether the 10 and 50 g sample sizes differed significantly showed a satisfactory observed variance ratio (Fobs) of 2.03 for computations of pooled standard deviations; paired f-test values of 0.952, 1.43, and 0.224 were computed for each of the 3 study samples. The results meet acceptable limits, since each sample’s r-test result is less than the published value of the |t|, which is 1.6909 for the test conditions. The null hypothesis is retained since the sample sizes do not give significantly different values for the mean analyte concentration. The percent coefficients of variation (CVs) for all samples tested were within the expected range. In addition, the variance due to sample mixing was evaluated using radioisotopelabeled materials, yielding an acceptable CV of 22.2%. The variance due to the assay procedure was also evaluated and showed an aflatoxin B, recovery of 78.9% and a CV of 11.4%. Results support the original premise that a sufficiently ground and blended sample would produce an analyte variance for a 10 g sample that was statistically comparable with that for a 50 g sample.

scholarly journals Zero order and area under curve spectrophotometric methods for determination of Levocetirizine in pharmaceutical formulation

2015 ◽  
Vol 1 (6) ◽  
pp. 270
Author(s):  
Audumbar Digambar Mali ◽  
Ritesh Bathe ◽  
Manojkumar Patil ◽  
Ashpak Tamboli
Keyword(s):  
Area Under The Curve ◽  
Zero Order ◽  
Pharmaceutical Dosage Forms ◽  
Mean Values ◽  
Spectrophotometric Methods ◽  
Ich Guidelines ◽  
Significant Difference ◽  
Curve Method ◽  
The Mean

Simple, fast and reliable spectrophotometric methods were developed for determination of Levocetirizine in bulk and pharmaceutical dosage forms. The solutions of standard and the sample were prepared in methanol. The quantitative determination of the drug was carried out using the zero order derivative values measured at 230 nm and the area under the curve method values measured at 227-234 nm (n=2). Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of Levocetirizine using 5-25?g/ml (r=0.998 and r=0.999) for zero order and area under the curve spectrophotometric method. All the proposed methods have been extensively validated as per ICH guidelines. There was no significant difference between the performance of the proposed methods regarding the mean values and standard deviations. Developed spectrophotometric methods in this study are simple, accurate, precise and sensitive to assay of Levocetirizine in tablets.

scholarly journals Influence of toothbrushing on enamel softening and abrasive wear of eroded bovine enamel: an in situ study

2006 ◽  
Vol 20 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Daniela Rios ◽  
Heitor Marques Honório ◽  
Ana Carolina Magalhães ◽  
Marília Afonso Rabelo Buzalaf ◽  
Regina Guenka Palma-Dibb ◽  
...  
Keyword(s):  
Abrasive Wear ◽  
The Other ◽  
In Situ Study ◽  
Significant Difference ◽  
The Mean ◽  
Student’S T ◽  
Bovine Enamel ◽  
Enamel Layer ◽  
Student’S T Test

This study assessed the surface softening and abrasive wear of eroded bovine enamel with or without the influence of toothbrushing. Five volunteers took part in this in situ study of 5 days. They wore acrylic palatal appliances containing 6 bovine enamel blocks divided in two rows with 3 blocks, which corresponded to the studied groups: erosion without toothbrushing (GI) and erosion with toothbrushing (GII). The blocks were subjected to erosion by immersion of the appliances in a cola drink for 10 minutes, 4 times a day. After that, no treatment was performed in one row (GI), whereas the other row was brushed (GII). The appliance was then replaced into the mouth. Enamel alterations were determined using profilometry and microhardness tests. Data were tested using paired Student’s t test (p < 0.05). The mean wear values (µm) and percentage of superficial microhardness change (%SMHC) were respectively: GI - 2.77 ± 1.21/91.61 ± 3.68 and GII - 3.80 ± 0.91/58.77 ± 11.47. There was a significant difference in wear (p = 0.001) and %SMHC (p = 0.001) between the groups. It was concluded that the wear was more pronounced when associated to toothbrushing abrasion. However, toothbrushing promoted less %SMHC due to the removal of the altered superficial enamel layer.

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