Determination of pH of Ammonia Latex

1931 ◽  
Vol 4 (2) ◽  
pp. 264-272
Author(s):  
J. McGavack ◽  
J. S. Rumbold
Keyword(s):  
Internal Resistance ◽  
Null Point ◽  
Glass Electrode ◽  
Hydrogen Electrode ◽  
High Degree ◽  
Work Done ◽  
Direct Use ◽  
Fair Degree ◽  
Made In

Abstract The pH of latex has been determined at various concentrations of ammonia (1) by the use of indicators, and (2) by the application of the glass electrode. The two curves thus obtained were comparable but not identical. It is shown that the glass electrode gives results reproducible with a high degree of accuracy up to pH 9.5 and a fair degree of accuracy up to pH 11.0. Above pH 11.0 it is necessary to calibrate each electrode. An ordinary galvanometer allowed measurement of the e. m. f. to 1 millivolt. The assymetry of the glass was so small as to be negligible. This paper covers the work done so far in these laboratories on the development of an accurate and rapid method for determining the pH of latex. From a practical viewpoint one of the most troublesome features of the direct use of a hydrogen electrode is the deposition of a film of rubber on the platinum, which by increasing the internal resistance of the cell, so reduces the sensitivity of the null point instrument that after a few determinations the apparatus must become inoperative. A more serious objection to this electrode is the uncertainty attached to measurements made in solutions containing proteins.

SOME NATIVE SAWFLIES OF THE GENUS NEODIPRION ATTACKING PINES IN EASTERN CANADA

1943 ◽  
Vol 21d (5) ◽  
pp. 109-144 ◽  
Author(s):  
C. E. Atwood ◽  
O. Peck
Keyword(s):  
Life History ◽  
Eastern Canada ◽  
Adult Females ◽  
Fair Degree ◽  
Made In

The genus Neodiprion has become more and more important in recent years because of the variety of species found on our native conifers and the increasing frequency of outbreaks caused by these insects. It is very difficult to distinguish between the species by means of adult characters only, so a study of different stages of the life history has been made. In this way it has been found possible to delimit most of the species with a fair degree of certainty.Keys are given for the determination of adult females of 11 and of larvae of 10 species attacking pines in Eastern Canada. Two of the species are described as new. The larvae of two species appearing in the first key and the adults of one species from the second are as yet unknown.

scholarly journals The Choice of Priority Actions Aimed at Ecological Rehabilitation of Standing and Low-flowing Lakes

2017 ◽  
Author(s):  
Keyword(s):  
Water Body ◽  
Calculated Data ◽  
Biogenic Element ◽  
Total Phosphorous ◽  
Internal Sources ◽  
Main Input ◽  
High Degree ◽  
Optimal Set ◽  
Made In

Methods of the choice of priority actions in rehabilitation of standing or lowflowing lakes whose unsatisfactory status is caused by either high degree of euthrophication or pollution with man-caused components or combination of these factors are presented. The methods are to be applied after taking of the decision on the necessity of a specific water body rehabilitation and it enables to calculate the main input flows of pollutants and biogenic material on the basis of field observations and calculated data for the water body and its catchment area; it enables to rate these flows and to determine the optimal set of methods for the water body effective rehabilitation and to forecast its conditions after implementation of these measures. The choice of de-euthrophication actions is based on the assessment of the total phosphorous input flows from external and internal sources to the water body whose limiting biogenic element is phosphorous, with their subsequent rating. The choice of actions connected with the man-caused ingredients impact mitigation is to be made in compliance with the same principle. Methods of determination of the total phosphorous or man-caused pollutants inflows to a water body from external and internal sources have been proposed. An example of the rehabilitation measures choice for euthrophic standing lake and low-flowing reservoir with low trophic status but actively being polluted with man-caused ingredients is presented.

Comparison of Two- and Three-Dimensional Methods for Assessment of Orientation of the Total Hip Prosthesis

1988 ◽  
Vol 29 (3) ◽  
pp. 357-361 ◽  
Author(s):  
K. Herrlin ◽  
H. Pettersson ◽  
G. Selvik
Keyword(s):  
Hip Prosthesis ◽  
Three Dimensional ◽  
Total Hip Prosthesis ◽  
Hip Prostheses ◽  
Total Hip ◽  
Total Hip Prostheses ◽  
Prosthetic Component ◽  
High Degree ◽  
Made In

A comparison of two- and three-dimensional methods for the determination of the orientation of total hip prostheses was made in a group of 57 patients. The acetabular inclination and the collum-diaphyseal angle measured on a.p. projections (2-D) were adequate in most cases for assessing how vertically the prosthetic component was inserted, but in individual cases with a high degree of version these measurements could be misleading. Anteversion measured in the transverse plane (2-D) was more sensitive to errors than planar anteversion measured as a rotation around the longest diameter of the ellipsoid projection of the acetabular opening, but it gave a rough estimate of the relation of the prosthetic components. Determination of the spatial (3-D) orientation of the components provides a precise estimate of the component relations.

scholarly journals A robust microbalance of high sensitivity. Suitable for weighing sorbed films

1929 ◽  
Vol 125 (799) ◽  
pp. 579-586 ◽  
Keyword(s):  
Plane Surface ◽  
Horizontal Tube ◽  
High Sensitivity ◽  
Null Point ◽  
Monomolecular Film ◽  
Wide Range ◽  
Beam Type ◽  
High Degree ◽  
Two Sides

The sorption balance of McBain and Baker may be made of high degree of sensitivity, but the total weight which it will then support is correspondingly diminished. For weighing a monomolecular film on a comparatively heavy plane surface it is necessary to use a balance of beam type. A balance sensitive to 4 x 10 -9 grams can be made sufficiently compact to be placed in a horizontal tube so that it may be used over a wide range of temperatures and pressures including the conditions necessary for freeing from sorbed material the surfaces to be weighed. such a balance may be so designed that the volumes of the two sides of the balance are equal and unaffected by buoyancy. If, likewise, there be placed upon the two sides of the balance equal volumes of the same substance but of different area of surface, the differential change of weight caused by adsorption will be measured directly. A final desideratum is that the balance should be of null point type and free from any bind of hysteresis. Steele and Grant described a microbalance made of fused quartz which was sensitive to 4 x 10 -9 grams and was capable of weighing 0.1 gram with an accuracy of 1 x 10 -7 gram, added improvements were described by Gray and Ramsay .Aston simplified the design of the beam and made a balance specially adapted to the determination of gas densities. Stock and Ritter made a further modification by replacing the fused charts bulks-edge with a pair of needle points. They also described a null-point balance in which a magnetised steel needle was sealed horizontally within the beam. The magnetic held from a bar magnet held vertically over the centre of the balance was used to compensate changes in level of the beam. The intensity of this controlling magnetic field was varied either by altering the distance between the bar magnet and the balance, or by increasing the held of the bar magnet electrically.

scholarly journals The factors determining the maximum work and the mechanical efficiency of muscle

1928 ◽  
Vol 103 (724) ◽  
pp. 234-251 ◽  
Keyword(s):  
High Efficiency ◽  
Mechanical Efficiency ◽  
Internal Resistance ◽  
Point Of View ◽  
Short Stimulus ◽  
Human Muscles ◽  
Maximum Work ◽  
Work Done ◽  
Speed Of Shortening

In order, in a prolonged contraction, to obtain the maximum work from a muscle, the load must be so adjusted that at every stage the muscle is just, and only just, able to overcome it; and the speed of shortening must be as low as possible. Levin and Wyrnan (1), in their work on the "viscosity" of muscles, employed an ergometer which, allowing the muscle to shorten at any described speed, measured the maximum work which it was capable of performing at that speed. Their instrument, which records a tension-length curve on a fixed smoked surface, is very accurate and convenient to use, and it is theoretically inconceivable that greater work—at a given constant speed—could be recorded by any other means. The only way to increase the work is to decrease the speed, in order to reduce the energy wasted in overcoming the internal resistance of the muscle. From the point of view of the mechanical efficiency of muscle ( i. e. , ratio of work done to total energy liberated) prolonged contractions are to be avoided, since they require large amounts of energy to be liberated in maintaining them (7). The matter has been discussed by one of us and his colleagues in several places (2), (3), (4), (5), p. 32, (6), pp. 48 and 81. It is clear that for a high efficiency the contraction must be of comparatively short duration: there is indeed, for human muscles, an optimum duration at which the efficiency is greatest. We were led therefore to a consideration of the maximum work obtainable in the response to a short stimulus, and to an experimental determination of the maximum mechanical efficiency of the frog's isolated muscle. The matter is much more complicated than is the simple case of a prolonged contraction, considered by Levin and Wyman, and it has required the examination of the effects of varying several different factors.

scholarly journals Comparison of the Board of Trade ampere-standard balance with the Ayrton-Jones current-weigher; with an appendix on the electromotive forces of standard cells

1908 ◽  
Vol 80 (540) ◽  
pp. 383-389 ◽  
Keyword(s):  
Technical College ◽  
National Physical Laboratory ◽  
Current Strength ◽  
Physical Laboratory ◽  
The Difference ◽  
Set Up ◽  
High Degree ◽  
A Current ◽  
Fair Degree

When the Board of Trade ampere balance was set up and verified in 1894, the platinum weight (marked A) used with the instrument was adjusted so that a current which deposited silver from a 15-per-cent. solution of silver nitrate at the rate of 1·118 milligrammes per second produced, on reversal, a change of force equal to the weight of A. At that period such a current was believed to represent the ampere , viz., 1/10 of a C. G. S. unit, with a fair degree of accuracy. During the last few years a new current weigher, designed at the Central Technical College, has been constructed at the National Physical Laboratory with a precision previously not obtained in any instrument for the absolute determination of current strength, and by means of it the electrochemical equivalent of silver has been determined to a very high degree of accuracy. We therefore considered it of interest to determine the difference between the units of current as measured by the two balances, and at the same time ascertain how nearly the ampere, as measured by the Board of Trade balance, deposits silver at the rate of 1·118 milligrammes per second.

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

The quantitative comparison of experimental and simulated diffraction contrast images

1995 ◽  
Vol 53 ◽  
pp. 102-103
Author(s):  
Stuart McKernan
Keyword(s):  
Image Processing ◽  
Personal Computer ◽  
Close Agreement ◽  
Quantitative Comparison ◽  
Image Simulation ◽  
Computing Power ◽  
Diffraction Contrast ◽  
Simulated Images ◽  
Made In

For many years the concept of quantitative diffraction contrast experiments might have consisted of the determination of dislocation Burgers vectors using a g.b = 0 criterion from several different 2-beam images. Since the advent of the personal computer revolution, the available computing power for performing image-processing and image-simulation calculations is enormous and ubiquitous. Several programs now exist to perform simulations of diffraction contrast images using various approximations. The most common approximations are the use of only 2-beams or a single systematic row to calculate the image contrast, or calculating the image using a column approximation. The increasing amount of literature showing comparisons of experimental and simulated images shows that it is possible to obtain very close agreement between the two images; although the choice of parameters used, and the assumptions made, in performing the calculation must be properly dealt with. The simulation of the images of defects in materials has, in many cases, therefore become a tractable problem.

Science of Ahangyol and Its Importance for Modern Scientific Thought

2019 ◽  
Vol 10 (5) ◽  
pp. 473-478
Author(s):  
Ahmad Gashamoglu ◽  
Keyword(s):  
Modern Science ◽  
Scientific Basis ◽  
New Paradigm ◽  
Islamic Philosophy ◽  
Scientific Thought ◽  
Religious Books ◽  
Strategic Approach ◽  
Scientific Potential ◽  
Made In

The Article briefly discusses the need for generation of the Science of Ahangyol, and this science’s scientific basis, object and subject, category system, scientific research methods and application options. Ahangyol is a universal science and may be useful in any sphere. It may assist in problem solving in peacemaking process and in many areas such as ecology, economics, politics, culture, management and etc. This science stipulates that any activity and any decision made in the life may only and solely be successful when they comply with harmony principles more, which are the principles of existence and activity of the world. A right strategic approach of the Eastern Philosophy and the Middle Age Islamic Philosophy and scientific thought has an important potential. This strategic approach creates opportunities to also consider irrational factors in addition to rational ones comprehensively in scientific researches. The modern scientific thought contributes to implementation of these opportunities. Ahangyol is a science of determination of ways to achieve harmony in any sphere and of creation of special methods to make progress in these ways through assistance of the modern science. Methods of the System Theory, Mathematics, IT, Astronomy, Physics, Biology, Sociology, Statistics and etc. are more extensively applied. Information is given on some of these methods. Moreover, the Science of Ahangyol, which is a new philosophical worldview and a new paradigm contributes to clarification of metaphysic views considerably and discovery of the scientific potential of religious books.

Is it necessary to calculate Young’s modulus in AFM nanoindentation experiments regarding biological samples?

2020 ◽  
Vol 12 ◽  
Author(s):  
S.V. Kontomaris ◽  
A. Malamou ◽  
A. Stylianou
Keyword(s):  
Young’S Modulus ◽  
Biological Samples ◽  
Young's Modulus ◽  
Reference Sample ◽  
Nonlinear Behavior ◽  
Accurate Method ◽  
Accurate Solution ◽  
Hertz Model ◽  
Work Done

Background: The determination of the mechanical properties of biological samples using Atomic Force Microscopy (AFM) at the nanoscale is usually performed using basic models arising from the contact mechanics theory. In particular, the Hertz model is the most frequently used theoretical tool for data processing. However, the Hertz model requires several assumptions such as homogeneous and isotropic samples and indenters with perfectly spherical or conical shapes. As it is widely known, none of these requirements are 100 % fulfilled for the case of indentation experiments at the nanoscale. As a result, significant errors arise in the Young’s modulus calculation. At the same time, an analytical model that could account complexities of soft biomaterials, such as nonlinear behavior, anisotropy, and heterogeneity, may be far-reaching. In addition, this hypothetical model would be ‘too difficult’ to be applied in real clinical activities since it would require very heavy workload and highly specialized personnel. Objective: In this paper a simple solution is provided to the aforementioned dead-end. A new approach is introduced in order to provide a simple and accurate method for the mechanical characterization at the nanoscale. Method: The ratio of the work done by the indenter on the sample of interest to the work done by the indenter on a reference sample is introduced as a new physical quantity that does not require homogeneous, isotropic samples or perfect indenters. Results: The proposed approach, not only provides an accurate solution from a physical perspective but also a simpler solution which does not require activities such as the determination of the cantilever’s spring constant and the dimensions of the AFM tip. Conclusion: The proposed, by this opinion paper, solution aims to provide a significant opportunity to overcome the existing limitations provided by Hertzian mechanics and apply AFM techniques in real clinical activities.

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