The Specific Gravity of Preserved Latex

1935 ◽  
Vol 8 (3) ◽  
pp. 448-455
Author(s):  
Edgar Rhodes
Keyword(s):  
Specific Gravity ◽  
Trade Association ◽  
Rubber Content ◽  
A Value ◽  
Straight Line ◽  
De Vries ◽  
The Subject ◽  
Rubber Phase ◽  
Content Range ◽  
Good Agreement

Abstract The Journal of the Rubber Research Institute of Malaya, 5, 234 (1934), contained a paper on the specific gravity of preserved latex written by the writer of this note. The paper has recently been made the subject of constructive comment by de Vries. As a result of the examination of 852 samples of preserved latex, a specific gravity/dry rubber content table was derived for preserved natural latices, and the dry rubber content range covered was wide enough to include natural unconcentrated latex in all the phases in which it is likely to be required by or become available to the commercial user. By the unavoidable expedient of extrapolation from the experimental results, a value of 0.902 was also derived for the specific gravity of the rubber phase in preserved latex. This value was in good agreement with the figure of 0.901 obtained by Scholtz and Klotz for “rubber” in fresh latex. On the other hand, de Vries, working with fresh latex had previously derived a value of 0.914 for the specific gravity of the rubber phase, and the specific gravity table used by the Rubber Trade Association of London for preserved latex gives on straight line extrapolation a value of 0.912. It seemed that the value indicated by the work of De Vries and that deduced from the table of the Rubber Trade Association were probably rather high, and certain experiments with centrifugal concentrated and centrifugal concentrate-skim mixtures were cited which provided some confirmatory evidence of this conclusion.

The Specific Gravity of Preserved Latex

1935 ◽  
Vol 8 (2) ◽  
pp. 284-296
Author(s):  
Edgar Rhodes
Keyword(s):  
Specific Gravity ◽  
Disperse Phase ◽  
Additional Data ◽  
Trade Association ◽  
Significant Feature ◽  
Rubber Content ◽  
De Vries ◽  
Rubber Phase

Abstract The literature on latex contains a number of references to the specific gravity of fresh latex, but published information on the specific gravity of preserved latex in the condition In which it reaches the consumer appears to be practically non-existent. de Vries and Scholtz and Klotz investigated the specific gravity of undiluted fresh latices of various dry rubber contents, and from their results each deduced the specific gravity of the disperse or rubber phase. The average specific gravity of the rubber globule as deduced by de Vries is 0.914. Scholtz and Klotz's value for the disperse phase is 0.901, which is appreciably lower than that of de Vries. Although. the published literature contains no references to the specific gravity of commercial preserved latex, the Rubber Trade Association of London gives a table of values in its latex contract forms, but details are lacking as to the total number of experimental observations which the table represents. A significant feature is that, by extrapolation of the dry rubber content values to 100 per cent, after the manner of Scholtz and Klotz, the figures obtained for the specific gravity of the rubber disperse phase is 0.912, which agrees fairly well with that of de Vries for fresh latex, and which is considerably higher than that of Scholtz and Klotz. In view of the paucity of information available on the specific gravity of preserved latex, it seemed desirable to obtain additional data and incidentally to make a further check on the published values for the specific gravity of the rubber disperse phase.

Specific Gravity of Latex and of Rubber

1940 ◽  
Vol 13 (3) ◽  
pp. 485-504
Author(s):  
H. Fairfield Smith
Keyword(s):  
Specific Gravity ◽  
Rubber Content ◽  
Rubber Phase ◽  
Almost All ◽  
Good Agreement

Abstract From observations on specific gravity and dry rubber content of latex, of centrifugal concentrates, and of latex-water mixtures, a number of attempts have been made to deduce the specific gravity of the rubber phase. Such estimates, after allowing for criticisms and adjustments which have been put forward, range from 0.901 to 0.914. But writers have made no attempt to consider how their calculations would be affected by treatments of the latex such as ammoniating and centrifuging, by different ways of evaluating the results, and by variations in temperature. When consideration is given to such matters almost all observations published during the last 20 years are found to be in good agreement one with another. Specific gravity, the ratio of the mass of a certain volume of a substance, at temperature t2, to that of the same volume of water, at temperature t1 is commonly designated dt2t2. To avoid excess affixes, when the temperature of the substance does not require to be stated, let:

The State of Polydispersion of Hevea Latex. I

1946 ◽  
Vol 19 (1) ◽  
pp. 176-186
Author(s):  
J. H. E. Hessels
Keyword(s):  
Protein Content ◽  
Hevea Brasiliensis ◽  
The State ◽  
Rubber Content ◽  
Rubber Latex ◽  
Latex Particles ◽  
Rubber Particles ◽  
The Subject ◽  
Points Of View ◽  
Good Agreement

Abstract The rubber particles in the latex of Hevea brasiliensis are present in the form of a polydispersion, and their diameters lie within the range of 0.1 to 3 microns. The rubber hydrocarbon itself is composed of a mixture of macromolecules of different degrees of polymerization. Rubber latex is, therefore, a system which is at the same time both polydispersed and polymolecular. It is well known that the degree of dispersion of a substance governs to a great extent certain properties of the substance. Moreover, astonishing as it may seem, in the great number of investigations which have been made of the composition and properties of latex and crude rubber, almost no attention has been paid to the part which may be played by the dimensions of the latex particles. However, in an investigation concerned with the centrifugation of latex, Loomis and Stump have called attention to this possibility, and in a study of latex obtained by fractionation, and in which the majority of the latex particles were of large dimensions, McGavack came to the conclusion that the protein content is proportional to the surface area of the globules. This limited knowledge of the subject seemed to warrant a more thorough study of the problem, which is of fundamental importance both from the theoretical and practical points of view. The investigation as a whole divided itself into three essential parts: (1) separation of latex into fractions containing particles of different sizes, and measurement of the state of dispersion in these fractions, (2) a study of the relation of these fractions to the composition of the rubber, i.e., the relation between the content of nonrubber components and the size of the latex particles, and (3) a study of the changes in the properties of the rubber hydrocarbon with change in the size of the latex particles. The latex used in this investigation was ordinary latex, containing 38–40 per cent dry-rubber content and preserved with ammonia. For the most important points, a concentrated latex (creamed latex containing 60 per cent dry-rubber content) was also tested. These two latices were about two years old when the investigation was started, and they gave results which were in good agreement with each other. In the present paper, only the data obtained with the first of the two latices are presented.

Standardisation of von Willebrand Factor in Therapeutic Concentrates: Calibration of the 1st International Standard for von Willebrand Factor Concentrate (00/514)

2002 ◽  
Vol 88 (09) ◽  
pp. 380-386 ◽  
Author(s):  
Dawn Sands ◽  
Andrew Chang ◽  
Claudine Mazurier ◽  
Anthony Hubbard
Keyword(s):  
Von Willebrand Factor ◽  
International Study ◽  
Expert Committee ◽  
International Standard ◽  
A Value ◽  
Significant Difference ◽  
Factor Concentrate ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Good Agreement

SummaryAn international study involving 26 laboratories assayed two candidate von Willebrand Factor (VWF) concentrates (B and C) for VWF:Antigen (VWF:Ag), VWF:Ristocetin Cofactor (VWF:RCo) and VWF:Collagen binding (VWF:CB) relative to the 4th International Standard Factor VIII/VWF Plasma (4th IS Plasma) (97/586). Estimates of VWF:Ag showed good agreement between different methods, for both candidates, and the overall combined means were 11.01 IU/ml with inter-laboratory variability (GCV) of 10.9% for candidate B and 14.01 IU/ml (GCV 11.8%) for candidate C. Estimates of VWF:RCo showed no significant difference between methods for both candidates and gave overall means of 9.38 IU/ml (GCV 23.7%) for candidate B and 10.19 IU/ml (GCV 24.4%) for candidate C. Prior to the calibration of the candidates for VWF:CB it was necessary to calibrate the 4th IS Plasma relative to local frozen normal plasma pools; there was good agreement between different collagen reagents and an overall mean of 0.83 IU per ampoule (GCV 11.8%) was assigned. In contrast, estimates of VWF:CB in both candidates showed large differences between collagen reagents with inter-laboratory GCV’s of 40%. Candidate B (00/514) was established as the 1st International Standard von Willebrand Factor Concentrate by the WHO Expert Committee on Biological Standardisation in November 2001 with assigned values for VWF:Ag (11.0 IU/ampoule) and VWF:RCo (9.4 IU/ampoule). Large inter-laboratory variability of estimates precluded the assignment of a value for VWF:CB.

Aortic tortuosity index as a predictor of type A aortic dissection

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
F Scalbert ◽  
O Milleron ◽  
M Para ◽  
R Raffoul ◽  
Q Pellenc ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Type A ◽  
Ct Scans ◽  
Control Group ◽  
Type A Aortic Dissection ◽  
Total Length ◽  
A Value ◽  
Straight Line ◽  
Patients At Risk ◽  
Geometric Length

Abstract Introduction The risk ok type A aortic dissection (AAD) depends on the degree of aortic wall's alteration, which can result in dilatation or tortuosity. The estimate of this risk relies solely on the evaluation of the diameter of the ascending aorta. Purpose The purpose of this study is to evaluate the presence and importance of aortic tortuosity in patients with type A aortic dissection. Method Postoperative CT scans of patients with type A aortic dissection were compared with CT scans from controls matched for gender and age. After 3D reconstruction, total length (actual distance along aortic center line = Ltot) and geometric length (length of a straight line between start and end of the aortic segment = Lgeo) were measured to calculate the tortuosity index (TI = Ltot / Lgeo). Results Ltot, Lgeo and TI from different aortic segments of the AAD group were higher than in the control group. Ltot and TI of the whole aorta (from aortic valve to bifurcation) were greater in patients with type A aortic dissection (527.7±46.1 mm vs. 475.8±39.7, p<0.0001; and 2.05±0.24 vs. 1.98±0.21, p=0.002 respectively). Total length and TI were greater after exclusion of the ascending part, and a value of this TI >1.3 identifies AAD patients with an accuracy of 74.8% (AUC = 0.792, p<0.0001). TI is altered by risk factors for aortic dissection: it increases with hypertension and age but not by tobacco use, and TI decreases in diabetes. Conclusions Type A aortic dissection is associated with longer aorta and increased aortic tortuosity. This index may help recognize patients at risk for type A aortic dissection. Calculation of tortuosity indexes Funding Acknowledgement Type of funding source: None

Heat-flow experiments in liquid 4He with a variable cylindrical geometry

1987 ◽  
Vol 174 ◽  
pp. 209-231 ◽  
Author(s):  
H. Gao ◽  
G. Metcalfe ◽  
T. Jung ◽  
R. P. Behringer
Keyword(s):  
Cylindrical Geometry ◽  
Small Scale ◽  
Onset Of Convection ◽  
Aspect Ratios ◽  
A Value ◽  
Prandtl Numbers ◽  
Convection Rolls ◽  
Flow Experiments ◽  
Increasing Function ◽  
Good Agreement

This paper first describes an apparatus for measuring the Nusselt number N versus the Rayleigh number R of convecting normal liquid 4He layers. The most important feature of the apparatus is its ability to provide layers of different heights d, and hence different aspect ratios [Gcy ]. The horizontal cross-section of each layer is circular, and [Gcy ] is defined by [Gcy ] = D/2d where D is the diameter of the layer. We report results for 2.4 [les ] [Gcy ] [les ] 16 and for Prandtl numbers Pr spanning 0.5 [lsim ] Pr [lsim ] 0.9 These results are presented in terms of the slope N1 = RcdN/dR evaluated just above the onset of convection at Rc. We find that N1 is only a slowly increasing function of [Gcy ] in the range 6 [lsim ] [Gcy ] [lsim ] 16, and that it has a value there which is quite close to 0.72. This value of N1 is in good agreement with variational calcuations by Ahlers et al. (1981) pertinent to parallel convection rolls in cylindrical geometry. Particularly for [Gcy ] [lsim ] 6, we find additional small-scale structure in N1 associated with changes in the number of convection rolls with changing [Gcy ]. An additional test of the linearzied hydrodynamics is given by measurements of Rc. We find good agreement between theory and our data for Rc.

Device Modeling of a-Si:H Alloy Solar Cells: Calibration Procedure for Determination of Model Input Parameters

1998 ◽  
Vol 507 ◽  
Author(s):  
M. Zeman ◽  
R.A.C.M.M. Van Swaaij ◽  
E. Schroten ◽  
L.L.A. Vosteen ◽  
J.W. Metselaar
Keyword(s):  
Solar Cell ◽  
Material Properties ◽  
Calibration Procedure ◽  
Model Parameters ◽  
Model Input ◽  
A Value ◽  
Input Parameters ◽  
Simulated Material ◽  
Good Agreement

ABSTRACTA calibration procedure for determining the model input parameters of standard a-Si:H layers, which comprise a single junction a-Si:H solar cell, is presented. The calibration procedure consists of: i) deposition of the separate layers, ii) measurement of the material properties, iii) fitting the model parameters to match the measured properties, iv) simulation of test devices and comparison with experimental results. The inverse modeling procedure was used to extract values of the most influential model parameters by fitting the simulated material properties to the measured ones. In case of doped layers the extracted values of the characteristic energies of exponentially decaying tail states are much higher than the values reported in literature. Using the extracted values of model parameters a good agreement between the measured and calculated characteristics of a reference solar cell was reached. The presented procedure could not solve directly an important issue concerning a value of the mobility gap in a-Si:H alloys.

Isotopic Thermal Diffusion Factors for Helium and Neon at Low Temperatures

1963 ◽  
Vol 18 (2) ◽  
pp. 242-245 ◽  
Author(s):  
W. W. Watson ◽  
A. J. Howard ◽  
N. E. Miller ◽  
R. M. Shiffrin
Keyword(s):  
Thermal Diffusion ◽  
Low Temperatures ◽  
Quantum Corrections ◽  
Intermolecular Potential ◽  
De Vries ◽  
Lower Temperature ◽  
Improved Accuracy ◽  
Good Agreement

With an all-metal “swing separator” having unique features, thermal diffusion factors αT for He3/He4 and Ne20Ne22 have been measured with improved accuracy down to average gas temperatures T̅=136°K. For helium αT is 0.0696 ± 0.0010 at 136°K, dropping gradually to 0.0651 ±0.0010 at 313°K. These data, plus measurements by Van der Valk and de Vries at somewhat higher temperatures, agree best with values predicted by an exp-six intermolecular potential with ε/k=9.16 and α=12.7. We are extending these helium measurements down to T=4°K for the lower temperature, to detect if possible quantum corrections to the intermolecular potential. For neon αT increases from 0.0166 ± 0.0010 at 136°K to 0.0233 ± 0.0020 at 310°K, considerably higher than our previously reported values. These T. D. factors for neon are in good agreement with values calculated from an exp-six potential with ε/k = 46.0 ± 0.6 and α=13.

scholarly journals Tasks and Social Functions of Adult Educationin the Perspective of Learning in Adulthood

2019 ◽  
pp. 117-132
Author(s):  
Zofia Szarota
Keyword(s):  
Adult Education ◽  
Lifelong Learning ◽  
Social Functions ◽  
The Subject ◽  
Content Range

The subject of the study are contemporary social functions of adult education included in the context of lifelong learning. I presented their determinants and consequences. These functions are significantly different from those set out by historical socio-economic and cultural circumstances. I present a proposition of a proprietary view of the typology and content range of these functions.

scholarly journals KEMAMPUAN MENULIS PUISI BERTEMA SUNGAI DENGANMETODE KARYA WISATA SISWA KELAS XMADRASAH ALIYAH MUHAMMADIYAH BANJARMASIN(ABILITY TO WRITE POETRY THEME RIVER USING WORKS METHOD THE CLASS X STUDENT MADRASAH ALIYAH MUHAMMADIYAH BANJARMASIN)

2020 ◽  
Vol 10 (2) ◽  
pp. 219
Author(s):  
Zulkifli Rusma Noortyani Gusti Putri Pathiya Arsyana
Keyword(s):  
Student Activities ◽  
Writing Ability ◽  
Final Grade ◽  
Analysis Techniques ◽  
Data Object ◽  
A Value ◽  
Field Note ◽  
The Subject ◽  
Data Inference ◽  
Bahasa Indonesia

AbstractAbility to Write Poetry Theme River using Works Method the Class X StudentMadrasah Aliyah Muhammadiyah Banjarmasin. The objectives to be obtainedfrom the results of this study are to describe the ability to write a river-themedpoem with the method of class X students of the Islamic MuhammadiyahMuhammadiyah Banjarmasin. To achieve these objectives, researchers usequalitative methods with data collection techniques with observation techniquesto provide an overview of how to teach teachers and student activities during thelearning process. This technique is also equipped with a field note format to obtaindata by observing the data object directly. Data analysis techniques usinginteractive model analysis were carried out starting from the stages of datacollection, data reduction, data presentation, data inference, and data verification(Miles and Huberman, 1984). This method is very appropriate to be used in thisstudy because it examines the subject and is carried out on learning. The resultsof the assessment are a collaboration of teachers and researchers using anassessment rubric based on elements and writing conventions with a value of 95.8.The Indonesian KKM score at the MA Muhammadiyah Banjarmasin is 70.Students who can write poetry are 92% or as many as 23 students who score aboveor equal to the KKM of Indonesian Language Subjects or above 70. That means23 students have a category able and there are 2 students or as much as 8% ofstudents who have a category of poor with a final grade below 70. elements orcontent of river-themed poetry contains the environment where students writepoetry found in environmental poetry teaches to love the environment more, alsocontains innuendos to those who often ignore it.Keywords: writing ability, travel tour method AbstrakKemampuan Menulis Puisi bertema Sungai dengan Metode Karya WisataSiswa Kelas X Madrasah Aliyah Muhammadiyah Banjarmasin. Tujuan yangakan diperoleh dari hasil penelitian ini adalahmendeskripsikan kemampuanmenulis puisi bertema sungai dengan metode karya wisata siswa kelas XMadrasah Aliyah Muhammadiyah Banjarmasin.Untuk mencapai tujuan ini,peneliti menggunakan metode kualitatif denganteknik pengumpulan data denganteknik observasi untuk memberikan gambaran umum tentang cara mengajar gurudan aktivitas siswa selama proses pembelajaran. Teknik ini juga dilengkapidengan format catatan lapangan untuk mendapatkan data dengan mengamatiobjek data secara langsung.Teknik analisis data menggunakan analisis modelinteraktif dilakukan mulai dari tahap pengumpulan data, reduksi data, penyajiandata, inferensi data, dan verifikasi data (Miles dan Huberman, 1984).Metode inisangat tepat untuk digunakan dalam penelitian ini karena meneliti subjek dandilakukan pada pembelajaran. Hasil penilaian merupakan kolaborasi dari gurudan peneliti dengan menggunakan rubrik penilaian berdasarkan elemen dankonvensi penulisan dengan nilai 95,8. Nilai KKM Bahasa Indonesia di MAMuhammadiyah Banjarmasin adalah 70. Siswa yang mampu menulis puisiterdapat 92% atau sebanyak 23 siswa yang memperoleh nilai di atas atau samadengan KKM Mata Pelajaran Bahasa Indonesia atau di atas nilai 70. Itu artinyaada 23 siswa memiliki kategori mampu dan ada 2 siswa atau sebanyak 8% siswayang memiliki kategori tidak mampu dengan nilai akhir di bawah 70. Elemen ataukonten puisi bertema sungai berisi keadaan lingkungan tempat siswa menulispuisi yangditemukan dalam puisi lingkungan mengajarkan untuk lebih mencintailingkungan, juga berisi sindiran-sindiran kepada pihak-pihak yang seringmengabaikannya.Kata-kata kunci:kemampuan menulis, metode karya wisata

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