scholarly journals Direct Measure of the Local Concentration of Pyrenyl Groups in Pyrene-Labeled Dendrons Derived from the Rate of Fluorescence Collisional Quenching

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2919
Author(s):  
Janine L. Thoma ◽  
Stuart A. McNelles ◽  
Alex Adronov ◽  
Jean Duhamel
Keyword(s):  
Rate Constant ◽  
Model Compound ◽  
Average Rate ◽  
Local Concentration ◽  
Direct Measure ◽  
Collisional Quenching ◽  
Model Free ◽  
Straight Line ◽  
The Difference ◽  
Pyrene Concentration

The model-free analysis (MFA) was applied to measure the average rate constant (<k>) for pyrene excimer formation (PEF) in a series of pyrene-labeled dendrons referred to as Pyx-G(N), where x (= 2N) is the number of pyrenyl labels born by a dendron of generation N ranging from 1 to 6. <k> was measured in four different solvents, namely tetrahydrofuran (THF), toluene, N,N-dimethylformamide (DMF), and dimethylsulfoxide (DMSO). <k> was found to increase linearly with increasing local pyrene concentration ([Py]loc), where [Py]loc had been determined mathematically for the Pyx-G(N) dendrons. The slope of each straight line changed with the nature of the solvent and represented kdiff, the bimolecular rate constant for PEF. kdiff depended on the solvent viscosity (η) and the probability (p) for PEF upon encounter between an excited and a ground-state pyrene. In a same solvent, kdiff for the Pyx-G(N) dendrons was about 360 ± 30 times smaller than kdiff obtained for ethyl 4-(1-pyrene)butyrate (PyBE), a pyrene model compound similar to the pyrene derivative used to label the dendrons. The massive decrease in kdiff observed for the Pyx-G(N) samples reflected the massive loss in mobility experienced by the pyrenyl labels after being covalently attached onto a macromolecule compared to freely diffusing PyBE. Interestingly, the kdiff values obtained for the Pyx-G(N) dendrons and the PyBE model compound followed similar trends as a function of solvent, indicating that the difference in behavior between the kdiff values obtained in different solvents were merely due to the changes in the η and p values between the solvents. Normalizing the <k> values obtained with the Pyx-G(N) dendrons by the kdiff values obtained for PyBE in the same solvents accounted for changes in η and p, resulting in a master curve upon plotting <k>/(fdiff × kdiff) as a function of [Py]loc, where fdiff was introduced to account for some pyrene aggregation in the higher generation dendron (Py64-G(6)). This result demonstrates that <k> represents a direct measure of [Py]loc in pyrene-labeled macromolecules.

Automatic Tread Gaging Machine

1979 ◽  
Vol 7 (1) ◽  
pp. 31-39
Author(s):  
G. S. Ludwig ◽  
F. C. Brenner
Keyword(s):  
Experimental Tests ◽  
Automatic Machine ◽  
Wear Rates ◽  
Handling Device ◽  
Straight Line ◽  
Component Systems ◽  
Before And After ◽  
Good Repeatability ◽  
The Difference ◽  
Straight Lines

Abstract An automatic tread gaging machine has been developed. It consists of three component systems: (1) a laser gaging head, (2) a tire handling device, and (3) a computer that controls the movement of the tire handling machine, processes the data, and computes the least-squares straight line from which a wear rate may be estimated. Experimental tests show that the machine has good repeatability. In comparisons with measurements obtained by a hand gage, the automatic machine gives smaller average groove depths. The difference before and after a period of wear for both methods of measurement are the same. Wear rates estimated from the slopes of straight lines fitted to both sets of data are not significantly different.

scholarly journals XXIII.—On the Disruptive Discharge of Electricity: An Experimental Thesis for the Degree of Doctor of Science, Department A

1878 ◽  
Vol 28 (2) ◽  
pp. 633-671 ◽  
Author(s):  
Alexander Macfarlane
Keyword(s):  
Copper Wire ◽  
Late Summer ◽  
The Other ◽  
Straight Line ◽  
Summer Session ◽  
The Difference ◽  
A Chain ◽  
The One ◽  
Metallic Parts ◽  
The University

The experiments to which I shall refer were carried out in the physical laboratory of the University during the late summer session. I was ably assisted in conducting the experiments by three students of the laboratory,—Messrs H. A. Salvesen, G. M. Connor, and D. E. Stewart. The method which was used of measuring the difference of potential required to produce a disruptive discharge of electricity under given conditions, is that described in a paper communicated to the Royal Society of Edinburgh in 1876 in the names of Mr J. A. Paton, M. A., and myself, and was suggested to me by Professor Tait as a means of attacking the experimental problems mentioned below.The above sketch which I took of the apparatus in situ may facilitate tha description of the method. The receiver of an air-pump, having a rod capable of being moved air-tight up and down through the neck, was attached to one of the conductors of a Holtz machine in such a manner that the conductor of the machine and the rod formed one conducting system. Projecting from the bottom of the receiver was a short metallic rod, forming one conductor with the metallic parts of the air-pump, and by means of a chain with the uninsulated conductor of the Holtz machine. Brass balls and discs of various sizes were made to order, capable of being screwed on to the ends of the rods. On the table, and at a distance of about six feet from the receiver, was a stand supporting two insulated brass balls, the one fixed, the other having one degree of freedom, viz., of moving in a straight line in the plane of the table. The fixed insulated ball A was made one conductor with the insulated conductor of the Holtz and the rod of the receiver, by means of a copper wire insulated with gutta percha, having one end stuck firmly into a hole in the collar of the receiver, and having the other fitted in between the glass stem and the hollow in the ball, by which it fitted on to the stem tightly. A thin wire similarly fitted in between the ball B and its insulating stem connected the ball with the insulated half ring of a divided ring reflecting electrometer.

scholarly journals Contribution of avoidable causes of death to premature mortality in Poland and selected European countries

2020 ◽  
Author(s):  
Bogdan Wojtyniak ◽  
Jakub Stokwiszewski
Keyword(s):  
Life Expectancy ◽  
Central Europe ◽  
Causes Of Death ◽  
Average Rate ◽  
Premature Mortality ◽  
European Countries ◽  
Annual Percent Change ◽  
Death Rates ◽  
Central European ◽  
The Difference

Our study, availing the new, agreed by the OECD and Eurostat, lists of preventable and treatable causes of death, seeks to quantify the contribution of avoidable causes to premature mortality and its dynamics in Poland and Central European countries – Czechia, Hungary, Lithuania and Slovenia, in comparison with Sweden serving as a benchmark country in 1999–2017. We calculated age standardised death rates for the broad groups of avoidable causes and more specific ones, which comprised preventable and treatable cancer and diseases of the circulatory system (DCS), preventable injuries and alcohol-related diseases. Deaths from not avoidable causes were also analysed. The analysis of time trends in the death rates and calculation of the Average Annual Percent Change (AAPC) for the overall trend were performed with joint-point models. The contribution of changes in mortality from avoidable causes to increase life expectancy during 1999–2017 and contribution of the difference in mortality from these causes to the difference in life expectancy between five countries and Sweden were based on the decomposition of temporary life expectancy between birth and age 75 [e(0-75)]. For the calculation of life expectancy, we used the classic Chiang method and the decomposition of life expectancy by the death causes and age was conducted with the Arriaga method. The AAPC of death rates from avoidable causes in 1999–2017 was similar in all the countries but Lithuania, where the decline started later. The decline in the death rates from not avoidable causes is much slower than the rates from avoidable causes. Mortality from treatable causes was decreasing faster than from preventable causes in most populations. In 1999–2017, the average rate of mortality decline for preventable cancer was greater among men than among women, while for treatable cancer the sex-related differences were much smaller and in favour of women. As for preventable and treatable death from DCS, their decrease was faster among women than men in all the countries but Sweden. Improvements in mortality from causes that could be avoided through prevention or treatment made substantial positive contributions to the overall change in life expectancy in all the countries. The differences in temporary life expectancy e(0-75) between the analysed Central European countries and Sweden were much smaller in 2017 than in 1999, due to the reduction of the gap in mortality from avoidable causes. Our results show that among men, and to a lesser extent among women, mortality from preventable causes contributes more than mortality from causes that can be effectively treated to shorter life expectancy in the countries of Central Europe than in Sweden. This indicates that in reducing the health gap between the inhabitants of Central Europe and Western Europe, the healthcare system should consider disease prevention even to a greater extent than just treating them.

scholarly journals The Level of Specific Endurance and Technical and Tactical Efficiency of Young Football Players of Different Level of Competition / Nivo specifične izdržljivosti i tehničko-taktičke efikasnosti mladih fudbalera različitog stepena takmičenja

2016 ◽  
Vol 10 (2) ◽  
Author(s):  
Toplica Stojanović ◽  
Slobodan Goranović ◽  
Aleksandar Šakanović ◽  
Darko Stojanović
Keyword(s):  
The Other ◽  
Measuring Instruments ◽  
Football Players ◽  
Five Factors ◽  
Straight Line ◽  
Specific Performance ◽  
The Difference

In order to determine at which level is the specific performance and technical and tactical efficiency of young players of different level of competition, and whether the level of competition can be an indicator of level differences of these abilities, a research was conducted on the sample of young football players aged 14 to 16 from the eight clubs, half of them competing in the higher and the other half in the lower level of competition. A sample of measuring instruments consisted of 13 tests for evaluation of five factors of specific endurance: starting endurance, stamina in maintaining the shallow formation, endurance during fast dribbling, ball pressing endurance, and evaluation of technical and tactical efficiency of football players. The results of the research showed that the young players of higher level of competition had significantly greater technical and tactical efficiency, as well as specific performance in tests which included curvilinear movement and dribbling, as well as control and passing the ball in motion, but the difference is not recorded with straight-line movements and sprints.

Pharmacokinetics of Acetaminophen in the Human Neonate: Formation of Acetaminophen Glucuronide and Sulfate in Relation to Plasma Bilirubin Concentration and D-Glucaric Acid Excretion

PEDIATRICS ◽  
1975 ◽  
Vol 55 (6) ◽  
pp. 818-825
Author(s):  
Gerhard Levy ◽  
Narinder N. Khanna ◽  
David M. Soda ◽  
Osami Tsuzuki ◽  
Leo Stern
Keyword(s):  
Rate Constant ◽  
Glucuronic Acid ◽  
Average Rate ◽  
Acid Excretion ◽  
Glucaric Acid ◽  
Bilirubin Concentration ◽  
Term Infants ◽  
Plasma Bilirubin ◽  
Acetaminophen Glucuronide ◽  
Excretion Rates

The purpose of this study was to determine if certain physiologic parameters (plasma bilirubin concentration and urinary excretion rate of D-glucaric acid) can be used to predict a newborn infant's ability to eliminate a phenolic drug. and particularly to predict the ability to conjugate that drug with glucuronic acid. Twelve healthy 2-to 3-day-old full-term infants with plasma bilirubin concentrations of 1.0 to 11.6 mg/100 ml and D-glucaric acid excretion rates of 0.131 to 0.345 mg/kg/day received a single oral dose of acetaminophen, 12 mg/kg. Urine was collected serially for 48 hours and analyzed for acetaminophen, acetaminophen glucuronide, acetaminophen sulfate, and D-glucaric acid. The biologic half-life of acetaminophen was 3.5 ± 0.85 hours (average ± SD) as compared to average values of 1.9 to 2.2 hours observed in five reported studies on a total of 39 adults. The rate constant for acetaminophen glucuronide formation in neonates was considerably smaller, on the average, than in adults but the average rate constant for acetaminophen sulfate formation was somewhat larger than in adults. There is no statistically significant correlation between these rate constants and either plasma bilirubin concentration or D-glucaric acid excretion. The results of this study suggest that the limited ability of neonates to conjugate phenolic drugs with glucuronic acid is compensated to a degree by a well-developed capability for sulfate conjugation.

Regularities of changes in microhardness in the volume of EDT-69N binder cured at different temperatures

2020 ◽  
Vol 4 ◽  
pp. 65-71
Author(s):  
E.A. Veshkin ◽  
◽  
V.I. Postnov ◽  
V.V. Semenychev ◽  
E.V. Krasheninnikova ◽  
...  
Keyword(s):  
Cross Section ◽  
High Sensitivity ◽  
Sample Volume ◽  
Curing Temperature ◽  
Molding Temperature ◽  
Parabolic Law ◽  
Dimensionless Coefficient ◽  
Straight Line ◽  
Different Temperatures ◽  
The Difference

The change in the microhardness over the thickness of samples made of EDT-69N binder cured in vacuum and at atmospheric pressure at temperatures from 130 to 170°C was investigated. It was found that the change in microhardness along the thickness of the samples occurs according to the parabolic law, with the maximum values being achieved in the middle of the sample cross-section along the thickness. With an increase in the molding temperature, the microhardness in the middle section of the sample increases from 222 MPa at a molding temperature of 130°C to 410 MPa during molding at 170°C. At the critical molding temperature (170°C), the microhardness in all zones of the specimen cross section (subsurface, semi-average, and core) levels off, while the parabolic dependence degenerates into a straight line. It is shown that the method of scratching (sclerometry) demonstrated a sufficiently high sensitivity to the state of samples cured at different temperatures. With an increase in the molding temperature, the width of the sclerometric grooves decreases. At a critical molding temperature of 170°C, the groove width is stabilized and becomes constant throughout the sample thickness. To characterize the difference in the values of the microhardness of the cured binder in the sample volume, it is proposed to use a dimensionless “coefficient of volume anisotropy,” which can take a positive, negative or zero value. With an increase in the curing temperature of the binder and, accordingly, with an increase in the microhardness of the sample, the coefficient of volume anisotropy decreases, and when the samples are molded at the critical temperature, it turns to zero, which indicates the absence of anisotropy.

Computational Investigation on the Dispersive Transport of Angiographic Contrast Injected Antegradely Into Flow in a Tube

2007 ◽  
Author(s):  
Qing Hao ◽  
Baruch B. Lieber
Keyword(s):  
Coordinate System ◽  
Cross Section ◽  
Single Molecule ◽  
Molecular Diffusion ◽  
Local Concentration ◽  
Dispersive Transport ◽  
Cross Sectional ◽  
Advection Dispersion ◽  
The Cross ◽  
The Difference

When a solute such as angiographic contrast is introduced into a solvent such as blood analog fluid flowing in a straight circular tube, it spreads under the combined action of molecule diffusion and the variation of velocity over the cross-section [8]. If two molecules are being carried in the flow, for example, one in the center and one near the wall, the rate of separation caused by the difference in bulk velocity will greatly exceed that caused by molecule motion. Given enough time, any single molecule would wander randomly throughout the cross section of the pipe because of molecular diffusion, and would sample at random all the advective velocities [4]. Therefore, Taylor [8] adopted the Lagrangian approach to the problem, casting the equations in a coordinate system that moves with the average velocity of the flow and replacing the molecular diffusion coefficient with a dispersion coefficient, and the local concentration with the cross sectional mean concentration. Recasting Taylor’s equation in an inertial coordinate system one obtained the so called advection-dispersion equation.

A quantitative measure of nonlinearity

1993 ◽  
Vol 39 (5) ◽  
pp. 766-772 ◽  
Author(s):  
K Emancipator ◽  
M H Kroll
Keyword(s):  
Analytical Method ◽  
Response Curve ◽  
Polynomial Regression ◽  
Quantitative Measure ◽  
Square Root ◽  
Straight Line ◽  
The Mean ◽  
The Difference ◽  
Definition Of ◽  
Fitting In

Abstract Quantitative measures of the nonlinearity of an analytical method are defined as follows: the "(dimensional) nonlinearity" of a method is the square root of the mean of the square of the deviation of the response curve from a straight line, where the straight line is chosen to minimize the nonlinearity. The "relative nonlinearity" is defined as the dimensional nonlinearity divided by the difference between the maximum and minimum assayed values. These definitions may be used to develop practical criteria for linearity that are still objective. Calculation of the nonlinearity requires a method of curve-fitting. In this article, we use polynomial regression to demonstrate calculations, but the definition of nonlinearity also accommodates alternative nonlinear regression procedures.

The acid-catalyzed demetalation of 1-(tri-n-butylstannyl)-2-phenylethyne. A surprisingly small β-stannyl effect

1996 ◽  
Vol 74 (7) ◽  
pp. 1366-1368 ◽  
Author(s):  
I. Egle ◽  
V. Gabelica ◽  
A.J. Kresge ◽  
T.T. Tidwell
Keyword(s):  
Key Words ◽  
Isotope Effect ◽  
Acid Concentration ◽  
Rate Constant ◽  
Perchloric Acid ◽  
Hydronium Ion ◽  
Stabilizing Effect ◽  
Aromatic Product ◽  
Acid Catalyzed ◽  
The Difference

Rates of conversion of 1-(tri-n-butylstannyl)-2-phenylethyne to phenylethyne in H2O and D2O solutions of perchloric acid were found to be proportional to acid concentration, giving the hydronium ion rate constant [Formula: see text] and the isotope effect [Formula: see text]. The magnitude of this isotope effect suggests that the reaction occurs by rate-determining hydron transfer to the substrate, producing a vinyl carbocation; this carbocation then loses its tributylstannyl group, giving phenylacetylene as the only detectable aromatic product. The hydronium ion rate constant, when compared to the rates of protonation of phenylethyne and 1-(trimethylsilyl)-2-phenylethyne, gives a β-stannyl stabilizing effect of δΔG≠ = 6.6 kcal mol−1 and a differential β-stannyl/β-silyl effect of δΔG≠ = 3.2 kcal mol−1. These stabilizations are very much smaller than previously reported β-stannyl effects. Possible reasons for the difference are suggested. Key words: β-stannyl effect, β-silyl effect, carbocation stabilization, protodemetalation.

scholarly journals A Bracketing Relationship between Difference-in-Differences and Lagged-Dependent-Variable Adjustment

2019 ◽  
Vol 27 (4) ◽  
pp. 605-615 ◽  
Author(s):  
Peng Ding ◽  
Fan Li
Keyword(s):  
Linear Models ◽  
Nonparametric Model ◽  
True Positive ◽  
Difference In Differences ◽  
Inverse Probability ◽  
Model Free ◽  
Lagged Dependent Variable ◽  
The Difference ◽  
Positive Effect ◽  
Theoretical Results

Difference-in-differences is a widely used evaluation strategy that draws causal inference from observational panel data. Its causal identification relies on the assumption of parallel trends, which is scale-dependent and may be questionable in some applications. A common alternative is a regression model that adjusts for the lagged dependent variable, which rests on the assumption of ignorability conditional on past outcomes. In the context of linear models, Angrist and Pischke (2009) show that the difference-in-differences and lagged-dependent-variable regression estimates have a bracketing relationship. Namely, for a true positive effect, if ignorability is correct, then mistakenly assuming parallel trends will overestimate the effect; in contrast, if the parallel trends assumption is correct, then mistakenly assuming ignorability will underestimate the effect. We show that the same bracketing relationship holds in general nonparametric (model-free) settings. We also extend the result to semiparametric estimation based on inverse probability weighting. We provide three examples to illustrate the theoretical results with replication files in Ding and Li (2019).

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