Reply to the Comments of K. Leinfelder on "Surface energy of liquids isolated in narrow capillaries"

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32664/1/0000030.pd

Anomalous behavior of liquids in isolated contact with solids

Anomalous liquid behavior is viewed as a result of an increase in surface tension in isolated capillaries. Using a derived prime equation for this change several phenomena are treated including the strength of liquid bridges between solids, the lowering of vapor pressure, increased solubility, and adsorption-desorption hysteresis. Using experimental data available on the strength of liquid bridges and vapor pressure decreases, indicates the surface tension of water in micron sized capillaries has a surface tension of over 700 dyne/cm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33680/1/0000192.pd

Tensile strength of liquid bridges under reduced pressures

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34045/1/0000322.pd

Adsorption of catechol and comparative solutes on hydroxyapatite

Contemporary medical and dental adhesives often have difficulty sticking to wet surfaces or weaken with long-term exposure to water. Substantial research has been dedicated to finding a means of achieving adhesion in an aqueous environment. A study evaluates the adsorption of catechol relative to other chemical groups as means of gauging how effective they may be as adsorptive groups in adhesives. Contact angle and surface-tension measurements of solutions of catechols and other chemical groups were used to determine their works of adhesion. Adsorption isotherms were also constructed to ascertain Langmuir constants. Solutes containing catechol groups were compared to solutes containing other polar groups to see how well catechol adsorbs to hydroxyapatite, the mineral component of bones and teeth, relative to other chemical groups found in adhesives. The results of this study show that catechol and molecules containing catechol groups have higher rates and energies of adsorption to hydroxyapatite than do groups such as alcohols, amines, and carboxylic acids. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 532–538, 2003Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34428/1/10041_ftp.pd

A one-dimensional color order system for dental shade guides

The purpose of this study was to re-arrange the master Bioform shade guide into a long-range one-dimensional color system based upon color difference. Although most shade guides may show local order when arranged according to hue, long-range order has not been established. However, shade guide arrangement according to a logical color order would be an advantage to the user. The first step in determining the color order was to measure the color of the shade guide teeth. A methodology was developed for measuring the color by use of a reflectance spectrophotometer. The precision of measurement was determined to be equal to CIE L*a*b* [Delta]E of 0.5. Spectra were obtained and converted into CIE L*a*b* and Munsell notation. The measured colors of the Bioform shades ranged from a Munsell hue of 0.9 Y to 3.5 Y; a value of 6.6 to 7.8; and a chroma of 1.9 to 4.1. The teeth were then arranged visually from light to dark. The correlation coefficient between the visual ranking and color difference was 0.95. There was an inverse correlation between visual ranking and Munsell value, with a correlation coefficient of 0.90. Therefore, the sequence according to color difference provided the better agreement with visual perception.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27704/1/0000090.pd

The effect of cesium-containing leucite additions on the thermal and mechanical properties of two leucite-based porcelains

It has been demonstrated that a Cs 2 O-stabilized leucite porcelain was susceptible to a stress-induced phase transformation, but toughening was not observed. 1 It was hypothesized that if Cs 2 O-stabilized leucite core particles were added to a cesium-free matrix porcelain, selected or designed to enhance the toughening mechanism, toughening would occur. A commercial porcelain (VP) and a synthesized leucite-based porcelain (NP) were the matrix materials. Core particles of Cs 2 O (0.0–2.0 mol%) containing synthetic leucite were mixed with the two cesium-free matrix porcelains and vacuum fired into specimens for testing. The toughness of both types of matrix-based materials was dependent upon cesium content of the added core particles with a maximum toughness reached for those containing 0.75 mol% Cs 2 O. The toughness of the 0.75 mol% specimens (1.42 MNm −3/2 for VP based and 2.15 MNm −3/2 for NP based) was statistically ( p < .02) higher than either of the matrix materials alone or the matrix materials containing added core particles of synthetic cesium-free leucite. However, the toughest materials (0.75 mol% Cs 2 O) were not the strongest materials, most likely because of large internal flaws. The results suggested that transformation toughening was possible. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 195–204, 2004Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34433/1/30008_ftp.pd

Evaluation of some properties of an opaque porcelain fired simultaneously with the body porcelain,

Recently, a porcelain-fused-to-metal opaque porcelain was introduced that does not require a separate firing before application of the body porcelain. The objective of this study was to determine the properties of this new opaque porcelain and its ability to bond to metal. The properties studied included flexural strength, linear firing shrinkage, coefficient of thermal expansion, powder particle size, and ability to bond to body porcelain and dental alloys. Sintering of this opaque porcelain was complete when fired at 1760 [deg] F (960 [deg] C) with a linear firing shrinkage of 13.1% +/- 0.2%. No boundary between the opaque and body porcelains could be found with a scanning electron microscope after firing at 1760 [deg] F (960 [deg] C). The mean flexural strengths were 99 +/- 7 and 101 +/- 8 MPa respectively, for this opaque porcelain and a conventional opaque porcelain, and were not significantly different as assessed with Student's t-test (p = 0.548). The coefficient of thermal expansion for this opaque porcelain was 13.3 +/- 0.2 x 10-6/ [deg] C. Particle size analysis showed a 63% increase in the particles below 5 [mu]m for this opaque porcelain and bonding to two alloys was adequate as indicated by its cohesive failure. Simultaneous firing of this special opaque porcelain and body porcelain produced satisfactory sintering, strength, and bonding to metal.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31266/1/0000172.pd

Capillary penetration between dissimilar solids

The major purpose of this study was to develop and evaluate a mathematical model for the capillary penetration of a liquid between two dissimilar plates. Attempts have been made in the past to apply the Young-Laplace equation to this situation, but without success because of the complex curvature of the meniscus. Instead, free energy considerations were used to derive the proposed equation. The equation obtained for the capillary rise h for a liquid of surface tension [gamma]LV into a space b between two plates whose contact angles with the liquid are [theta]1 and [theta]2 was found to be: , where d is the liquid density and g is the gravitational constant.Experimental values of capillary penetration between combinations of three liquids and several solids were obtained with the use of the hyperbola method. A factorial design was employed. These data were compared with those predicted by means of the proposed equation. Regression, correlation, and analysis of variance were used to test for the degree and significance of the association between the predicted and observed values. These results and a dimensional analysis indicate that the proposed equation is satisfactory.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33195/1/0000583.pd

BMQ

BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals