An apparatus was developed to measure the conductance change of electrolytes in the presence of high electric fields to a high degree of accuracy, end is described herein. The apparatus employs square wave pulse excitation to a special conductivity bridge, and permits direct observation of pulse shape on a high speed oscilloscope, as well as separate compensation of resistive and capacitive unbalance. With this apparatus, the high-field electric conductances of several solutions of biologically interesting substances were investigated and classified. The substances investigated, together with the observed increment in electric conductance at a field strength of 10⁵ volts per cm., are listed: 1. glutamine (1.25 x 10⁻⁴M), 0.56% 2. 1 (﹢) arginine monhydrochloride (2.0x10⁻⁴M), 0.48% 3. acetic acid (3.75 x 10⁻⁴M), 4.6% 4. p-amino benzoic acid (5 x 10⁻³M), 5.5% 5. sulfanilic acid (6.55 X 10⁻⁵M), 1.4% 6. 1 (﹢) glutamic acid (1.22 x 10⁻³M), 2.6% 7. glycine (0.61 M), 1.9% 8. protamine sulfate (7.9 x 10⁻⁵g/cc.) 40% 9. agar (3 x 10⁻⁴ g/cc), 37% Some of the observed results have been compared with those obtained by other methods, while the remaining substances have not been previously reported. The results were discussed in the light of available theoretical information on the high-field conductance effect in various types of electrolytes. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The cell constant of a direct current conductivity cell was measured using as a standard 0.1M and 0.01M potassium chloride solutions and specific conductivity data obtained by G. Jones and M. Prendergast. The results obtained for either of the solutions were exact to within one or two parts in ten thousand, but a difference of 0.6% existed between the two cell constant values. In order to investigate more exactly the nature of this variation, other concentrations were measured using as a standard the data obtained by T. Shedlovsky, A.S. Brown, and D.A. Maclnness. Certain factors in the design of a direct current cell have been considered and suggestions for future work offered. Studies have been made of the anodic properties of strained copper wire in the cell Cu (strained) ⃒ CuSO₄ ⃒ Cu (normal). Two copper wires were immersed in copper sulphate solution. Weights were added to one of these and the potential difference measured potentiometrically or with a vacuum tube volt-meter. The results obtained show that (1) the relaxation of this potential is approximately exponential, (2) very little potential is developed until a critical strain is applied, (3) after a certain strain has been applied the peak potential developed becomes constant with increasing strain, (4) the magnitude of the effect is dependant on the concentration of the solution, (5) the magnitude and direction (anodic or cathodic) of the potential is dependant upon the components of the electrolyte. / Science, Faculty of / Chemistry, Department of / Graduate

published_or_final_version / Chemistry / Master / Master of Philosophy

No description available.

In recent years, several attempts have been made to develop instrumentation to aid in the measurement of soil water electrical conductivity. Each of the instruments have specific limitations. This dissertation discusses the available methods of measuring this parameter and indicates the limitations of the transducers which have been described in the literature. Also, discussed are the basic theories of operation of these transducers and definitions related to soil salinity in general. The major objective of this research was to develop a new transducer which would be a significant improvement over existing types of instrumentation. It is believed that this research has led to the development of two transducers of different geometries which can assess the soil water conductivity over a wider range of matric potential just as rapidly and accurately as the next best unit. At the same time the new transducers incorporate automatic temperature compensation which has not been done by any other field instrumentation of its type. Also presented, is the application of heat transfer theories to the diffusion of ions from the transducer to the surrounding environment, Application of this theory allows one to predict how the transducer will respond to a step change in ion concentration in an unsaturated soil system where the only process involved is diffusion. Good agreement between experimental measurements and predicted response indicates that the model may also be useful in further refinements of the transducer.

No description available.

No description available.

by Zhao Wei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 58-74). / Declaration --- p.i / Acknowledgements --- p.iii / Summary --- p.iii / Abbreviations --- p.v / Chapter CHAPTER 1 --- LITERATURE REVIEW --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Anatomy and functions of the epididymis --- p.1 / Chapter 1.2.1 --- Anatomy of the epididymis --- p.1 / Chapter 1.2.2 --- Histology and cytology of the epididymis --- p.2 / Chapter 1.2.3 --- Innervation and vasculation of the epididymis --- p.4 / Chapter 1.2.4 --- Sperm maturation and fertility in the epididymis --- p.6 / Chapter 1.2.5 --- Absorptive and secretory process of the epididymal epithelium --- p.8 / Chapter 1.2.6 --- Regulation of epididymal anion secretion --- p.9 / Chapter 1.3 --- Project aims --- p.12 / Chapter CHAPTER 2 --- METHODS AND MATERIALS --- p.13 / Chapter 2.1 --- Tissue preparation --- p.13 / Chapter 2.2 --- Light microscopic immunohistochemistry --- p.13 / Chapter 2.3 --- Cell culture and radioimmunoassay --- p.14 / Chapter 2.4 --- Cell culture and short -circuit current (Isc) measurement --- p.15 / Chapter 2.5 --- Reagents --- p.16 / Chapter 2.6 --- Statistical analysis --- p.16 / Chapter CHAPTER 3 --- LOCALIZATION AND DISTRIBUTION OF angiotensin ii in the rat epididymis --- p.17 / Chapter 3.1 --- Introduction --- p.17 / Chapter 3.2 --- Results --- p.18 / Chapter 3.2.1 --- Immunohistochemical localization of angiotensin II --- p.18 / Chapter 3.2.2 --- Angiotensin II activity measured by radioimmunoassay --- p.31 / Chapter 3.3 --- Discussion --- p.31 / Chapter CHAPTER 4 --- CELLULAR MECHANISM OF cAMP-DEPENDENTE BICARBONATE SECRETION IN RAT EPIDIDYMAL EPITHELIUM --- p.38 / Chapter 4.1 --- Introduction --- p.38 / Chapter 4.2 --- Results --- p.40 / Chapter 4.2.1 --- Effects of Cl and HCO3- on cyt-cAMP stimulated Isc in rat epididymal epithelia --- p.40 / Chapter 4.2.2 --- Effects of inhibitors on the cpt-cAMP stimulated Iscin HCO3- free solution --- p.41 / Chapter 4.2.3 --- Effects of inhibitors on the cpt-cAMP stimulated Isc in Cl-free solution --- p.41 / Chapter 4.2.4 --- Effect of hexokinase on cyt-cAMP induced Isc --- p.48 / Chapter 4.3 --- Discussion --- p.49 / Chapter CHAPTER 5 --- CONCLUSION --- p.55 / References --- p.58 / Publications --- p.74

Solution density modelling is important in hydrometallurgical processes as accurate predictions of single and mixed electrolytes can be used in the design of equipment and their sizing, heat transfer calculations and choosing of materials for construction. This research project entails modeling of electrolyte solutions by extending the Laliberte and Cooper (compound level) model to ionic level where an electrolyte solution is modeled as a mixture of cations, anions and water molecules. This modeling predicts single and mixed electrolyte density as a function of electrolyte temperature in degrees Celsius; water, cation and anion apparent volumes in cubic centimeters; and their respective concentrations in the electrolyte as mass fractions. The model was developed by fitting single electrolyte density data reported in literature using the least squares method in Microsoft Excel®. The following 26 single electrolyte solutions were used in the fitting exercise: Al2(SO4)3, BaCl2, CaCl2, CdSO4, CoCl2, CuSO4, FeCl3, FeSO4, HCl, HCN, HNO3, K2CO3, LiCl, MgSO4, MnCl2, Na2SO3, NaF, NaI, NaOH, (NH4)2SO4, NiCl2, SrCl2, ZnCl2, ZnBr2, (NH4)2C2O4 and KNO2. The above electrolytes attributed to the following ions: Al3+, Ba2+, Ca2+ Cd2+, Co2+, Cu2+, Fe3+, Fe2+, H+1, K+1, Li+1, Mg2+, Mn+2, Na+1, NH4+1, Ni2+, Sr+2, Zn2+, SO42-, Cl-1, CN-1, NO3-1, CO32-, OH-1, SO32-, Br-1, F-1, I-1, C2O4-2 and NO2-1. This translated to a combination of at least 216 single electrolyte solutions which could be feasibly modeled, and a solution with at most 10 anions for mixed electrolytes, which is comparable with practical hydrometallurgical solutions. A database of volumetric parameters was generated comprising a total of 18 cations and 12 anions. The validation of the developed model was done by predicting densities for both single and mixed electrolytes not used in the fitting exercise. The average density error i.e. the difference between experimental and model density for the single electrolyte solutions was 22.62 kg m-3 with a standard deviation of 39.66 kg m-3. For the mixed electrolytes, the average density error was 12.34 kg m-3 with a standard deviation of 24.48 kg m-3. These calculated errors translated to a maximum percentage average error of less than 4% for single electrolyte solutions and maximum average percentage of less than 3% for mixed electrolyte solutions.

Passivation, local anodic depassivation and pitting corrosion of stainless steels in bulk and under thin phase layers of acid sulphate and neutral chloride solutions have been studied. A number of electrochemical, chemical, metallographic and physical techniques were employed in this study. The choice of stainless steels, test solutions and methods of investigations was based on scientific expediency and practical availability. For the first time in electrochemical and corrosion characteristics of passivation, local anodic depassivation and pitting corrosion of stainless steels were obtained in thin layers and compared with those in bulk electrolytes. It was demonstrated that the thickness of the electrolyte layer can influence the passivation process and, under certain conditions, the kinetics of pitting erosion. Several tests were conducted and results given. It was shown that the prognosis of corrosion behaviour of some stainless steels in sulphur dioxide contaminated atmosphere based on electrochemical measurements in bulk electrolytes can be erroneous. The same measurements carried out in thin phase layers enable more accurate prediction. However, the prognosis of the relative resistance of the stainless steels to pitting corrosion in the clean chloride-containing atmosphere may be based on conventional electrochemical measurements in the bulk of corresponding electrolytes / Doctor of Philosophy (PhD)