Evaluation of Natural Rubber from Clones of Hevea Brasiliensis

2002 ◽  
Vol 75 (1) ◽  
pp. 171-177 ◽  
Author(s):  
Mariselma Ferreira ◽  
Rogério M. B. Moreno ◽  
Paulo S. Gonçalves ◽  
Luiz H. C. Mattoso
Keyword(s):  
Natural Rubber ◽  
Linear Correlation ◽  
Hevea Brasiliensis ◽  
Cold Season ◽  
The State ◽  
Rubber Content ◽  
Good Linear ◽  
Mooney Viscosity ◽  
In The Beginning ◽  
Good Linear Correlation

Abstract The latex and natural rubber from rubber trees [Hevea brasiliensis (Willd. exAdr. de Juss.) Muell. Arg.] from clones (RRIM 600, IAN 873, GT 1 and PB 252) recommended to the state of São Paulo, Brazil, were studied in three different tapping systems. The parameters studied were dry rubber content (DRC), percentages of ash and of nitrogen, Wallace Plasticity (P0) and Mooney Viscosity (VR). The rubber properties vary considerably as a function of clone type, tapping method and season of the year. DRC tends to decrease in the beginning of the dry, cold season (May and June), whereas both nitrogen % and ash % increase in the same period. A good linear correlation was obtained for P0 and VR. The highest P0 and VR were obtained for RRIM 600.

scholarly journals Technological properties of latex and natural rubber of Hevea brasiliensis clones

2005 ◽  
Vol 62 (2) ◽  
pp. 122-126 ◽  
Author(s):  
Rogério Manoel Biagi Moreno ◽  
Mariselma Ferreira ◽  
Paulo de Souza Gonçalves ◽  
Luiz Henrique Capparelli Mattoso
Keyword(s):  
Natural Rubber ◽  
Hevea Brasiliensis ◽  
Critical Period ◽  
Technical Standard ◽  
Technological Properties ◽  
Rubber Content ◽  
Standard Methods ◽  
Climatic Variations ◽  
Temperature And Precipitation ◽  
In The Beginning

Rubber industry has increased the requirements for quality and uniformity of natural rubber produced in Brazil. Technological properties of latex and natural rubber of clones GT 1, PB 235, IAN 873 and RRIM 600 [Hevea brasiliensis (Willd. Former Adr. de Juss.) Muell.- Arg] were evaluated by standard methods of the dry rubber content (DRC%), percentage of nitrogen (N%) and percentage of ashes (ASH%) in two consecutive years; data were correlated with temperature and precipitation. Properties of latex and natural rubber varied (P < 0.01) as a function of clone type and among tappings. DRC decreased in the beginning of the dry season (May to June) and N% and ASH% increased in the same period. April to June was a critical period, when N% was above 0.60%, out of standards established by the technical standard ABNT/NBR in Brazil. Clone RRIM 600 was less susceptible to climatic variations.

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.

scholarly journals Quantifying Mold Biomass on Gypsum Board: Comparison of Ergosterol and Beta-N-Acetylhexosaminidase as Mold Biomass Parameters

2003 ◽  
Vol 69 (7) ◽  
pp. 3996-3998 ◽  
Author(s):  
M. Reeslev ◽  
M. Miller ◽  
K. F. Nielsen
Keyword(s):  
Stationary Phase ◽  
Linear Correlation ◽  
Stachybotrys Chartarum ◽  
Gypsum Board ◽  
Biomass Density ◽  
Activity Data ◽  
Good Linear ◽  
Ergosterol Content ◽  
Good Linear Correlation

ABSTRACT Two mold species, Stachybotrys chartarum and Aspergillus versicolor, were inoculated onto agar overlaid with cellophane, allowing determination of a direct measurement of biomass density by weighing. Biomass density, ergosterol content, and beta-N-acetylhexosaminidase (3.2.1.52) activity were monitored from inoculation to stationary phase. Regression analysis showed a good linear correlation to biomass density for both ergosterol content and beta-N-acetylhexosaminidase activity. The same two mold species were inoculated onto wallpapered gypsum board, from which a direct biomass measurement was not possible. Growth was measured as an increase in ergosterol content and beta-N-acetylhexosaminidase activity. A good linear correlation was seen between ergosterol content and beta-N-acetylhexosaminidase activity. From the experiments performed on agar medium, conversion factors (CFs) for estimating biomass density from ergosterol content and beta-N-acetylhexosaminidase activity were determined. The CFs were used to estimate the biomass density of the molds grown on gypsum board. The biomass densities estimated from ergosterol content and beta-N-acetylhexosaminidase activity data gave similar results, showing significantly slower growth and lower stationary-phase biomass density on gypsum board than on agar.

Effect of Limestone Powder on Autogenous Shrinkage of Concrete

2011 ◽  
Vol 88-89 ◽  
pp. 767-771
Author(s):  
Bin Wang ◽  
You Ping Ding ◽  
Jing Gao ◽  
Jin Fang Sun ◽  
Miao Miao Cui ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Linear Correlation ◽  
Autogenous Shrinkage ◽  
Limestone Powder ◽  
Subsequent Reduction ◽  
Reduction Stage ◽  
Good Linear ◽  
Good Linear Correlation

The effect law and mechanism of limestone powder on autogenous shrinkage of concrete was studied. The results indicate that limestone powder accelerates autogenous shrinkage speed of concrete on which effect of fineness is little, and limestone powder reduces autogenous shrinkage which decreases with the increase of fineness. The change law of autogenous shrinkage of concrete is consistent with that of chemically combined water of paste. Autogenous shrinkage of concrete is also divided into 2 stages according to the initial vapor saturated stage and subsequent reduction stage of interior relative humidity, with both showing a good linear correlation at each stage.

scholarly journals Linear correlation between Debye temperature and lattice thermal conductivity in II-VI and III-V semiconductors

2015 ◽  
Vol 3 (2) ◽  
pp. 216 ◽  
Author(s):  
Salah Daoud
Keyword(s):  
Thermal Conductivity ◽  
Simple Model ◽  
Debye Temperature ◽  
Rock Salt ◽  
Linear Correlation ◽  
Lattice Thermal Conductivity ◽  
Empirical Relationship ◽  
Average Percentage ◽  
Good Linear ◽  
Good Linear Correlation

<p>A simple linear empirical relationship between high intrinsic lattice thermal conductivity K, and Debye temperature θ<em><sub>a</sub></em> is suggested from data on high intrinsic lattice thermal conductivity K, and Debye temperature θ<em><sub>a</sub></em> for some selected II-VI and III-V cubic zincblende type, and I-VII and II-VI rock-salt type binary semiconductors. A good linear correlation between Debye temperature and the high intrinsic lattice thermal conductivity was obtained. The minimum average percentage deviations in the present approach reveal that our simple model prove its identity and soundness compared to those of other author relations.</p>

Determination of Imidacloprid Residues in Chinese Cabbage by UPLC-MS/MS

2014 ◽  
Vol 852 ◽  
pp. 274-277
Author(s):  
Yu Bing Zha ◽  
Mao Fang Huang ◽  
Chun Liang Yang ◽  
Ming Yue Wang ◽  
Xiao Fang Wang ◽  
...  
Keyword(s):  
Chinese Cabbage ◽  
Linear Correlation ◽  
Good Linear ◽  
Calibration Curves ◽  
Relative Standard ◽  
External Standard ◽  
Standard Calibration ◽  
Standard Deviations ◽  
Good Linear Correlation

A method for determination of imidacloprid in Chinese Cabbage was established by using UPLCMS/MS. and the samples are extracted with acetontrile,and the extract is cleaned up by Florisil SPE cartridges and evaporated.Choromatographic separation was performed on a C18 column,and determined by UPLC-MS/MS.The external standard calibration curves were used for quantification. The results showed that a good linear correlation was obtained in the range of 0.005-0.1ug/mL. The limit of quantif icat ion w as 0. 008 mg/ kg .The average recoveries and the relative standard deviations were in the range of 84.9 %~92.7 % and 0.9 %~6.2 %, respectively. It is applicable to the determination of imidacloprid redidue in Chinese cabbage.

Kinetic energy analysis of atomic multiplets. II. smdn configurations

1996 ◽  
Vol 74 (6) ◽  
pp. 775-780 ◽  
Author(s):  
Toshikatsu Koga ◽  
Hidenori Aoki ◽  
Ajit J. Thakkar
Keyword(s):  
Kinetic Energy ◽  
Total Energy ◽  
Linear Correlation ◽  
Energy Analysis ◽  
Energy Difference ◽  
Good Linear ◽  
Hartree Fock ◽  
Electronic Configurations ◽  
Total Energy Difference ◽  
Good Linear Correlation

A kinetic energy analysis of total energy differences in 822 atomic multiplets arising from smdn (m = 0,1,2; n = 2–8) electronic configurations is performed within the nonrelativistic, restricted Hartree–Fock framework. For the 444 multiplets arising from the dn and s2dn configurations of 27 atoms in groups 2–10, a very good linear correlation between the total energy difference and the kinetic energy difference of the outermost d-electrons is demonstrated. For the 378 multiplets arising from the sdn configuration, on the other hand, a good linear correlation is obtained provided that the multiplets are classified into groups based on spin multiplicity. Key words: kinetic energy, atomic multiplets, smdn configurations, Hartree–Fock approximation.

NMR-spektroskopische Untersuchungen an Chalkogenverbindungen, II [1]. 125Te-, 77Se-, 19F- und 13C-chemische Verschiebungen von CF3-substituierten Selen- und Tellurverbindungen [2] / NMR Spectroscopic Studies on Chalcogen Compounds, II [1]. 125Te-, 77Se-, 19F- and 13C Chemical Shifts of CF3 Substituted Selenium and Tellurium Compounds [2]

1981 ◽  
Vol 36 (5) ◽  
pp. 535-543 ◽  
Author(s):  
Willy Gombler
Keyword(s):  
Linear Correlation ◽  
Chemical Shifts ◽  
Electron Excitation ◽  
Spectroscopic Studies ◽  
Excitation Energies ◽  
Selenium Compounds ◽  
13C Chemical Shifts ◽  
Good Linear ◽  
Nmr Data ◽  
Good Linear Correlation

77Se chemical shifts of compounds CF3SeX exhibit an extraordinary good linear correlation with Huggins‘ electronegativities of χx. A range of 1051 ppm is covered for χx values between 1.9 and 3.15. Effective electronegativities are derived from the δ(77Se) values. For some compounds unexpected 77Se chemical shifts are found. This indicates an uncommon electronic constitution at selenium. Electron excitation energies are reported for some of the compounds and their importance for the paramagnetic shielding term is discussed. The relative shieldings of the tellurium compounds are analogous to those of the corresponding selenium compounds. In contrast to 77Se, the 19F shieldings of CF3EX compounds (E = chalcogen) depend inversely on the electronegativity of E and X. The 13C chemical shifts do not correlate with the χx values. NMR data of some CF3Se(IV) and CF3Te(IV) compounds are also reported for comparison

THE SYSTEMATIC BEHAVIOR IN THE FRAGMENTS OF THE CALCIUM ISOTOPES PROJECTILE FRAGMENTATION

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1545-1552 ◽  
Author(s):  
CHUN-WANG MA ◽  
HUI-LING WEI ◽  
YU-QI LI
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Linear Correlation ◽  
Binding Energies ◽  
Projectile Fragmentation ◽  
Skin Thickness ◽  
Neutron Skin ◽  
Good Linear ◽  
Calcium Isotopes ◽  
Good Linear Correlation

We have calculated the cross sections of the fragments produced in the projectile fragmentation of the even 36–52 Ca isotopes using the statistical abrasion-ablation model. The isospin effect in the projectile fragmentation are studied by investigating the peak positions and the widths of the fragment isotopic cross section distributions. The peak positions of the fragments isotopic cross section distributions have good linear correlation to the Z of the fragments and the correlations are fitted using the linear function. The correlations between slopes b and the binding energies of the neutron ( S n) of the projectile nuclei, the differences between the binding energies of the neutron and proton( S n- S p) of the projectile nuclei and the neutron-skin thickness (δnp) are studied. It is found that b and δnp has a good linear correlation for the neutron-rich projectile nuclei.

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