Ultraviolet Absorption Spectra and Dissociation Constants of Diamino-1,3,5-triazines

This paper presents ultraviolet absorption spectra of two diamino-1,3,5-triazines, namely 1,3,5-triazine-2,4-diamine (DT) and 6-chloro-1,3,5-triazine-2,4-diamine (ClDT). The spectra were fitted to the log-normal distribution. In the more energetic zone of the spectrum both compounds presented common bands, placed around 204-205 and 223-226 nm (depending on the pH of the medium). At higher wavelengths the spectra were different, with bands appearing in the range 235-267 nm. From variations of the maximum absorbances of the individual bands, the pKb values 3.5 ± 0.2 and 1.2 ± 0.1 were obtained for protonation of the ring nitrogen placed between the amine radicals of DT and ClDT, respectively, and 9.35 ± 0.2 and 11.5 ± 0.1 for dissociation of the amino groups of DT and ClDT, respectively.

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Quantitative description of the absorption spectra of the coenzyme in glycogen phosphorylases based on log-normal distribution curves

Biochemical Journal ◽

10.1042/bj2920225 ◽

1993 ◽

Vol 292 (1) ◽

pp. 225-229 ◽

Cited By ~ 6

Author(s):

J Donoso ◽

F Muñoz ◽

F Garcia Blanco

Keyword(s):

Normal Distribution ◽

Absorption Spectra ◽

Aromatic Ring ◽

Glycogen Phosphorylase ◽

Quantitative Description ◽

Tautomeric Equilibrium ◽

Ionization State ◽

Coenzyme Binding ◽

Log Normal ◽

Log Normal Distribution

The absorption spectra of the coenzyme [pyridoxal 5′-phosphate (PLP)] in glycogen phosphorylase a (GPha), glycogen phosphorylase b (GPhb) and of the latter bound to various effectors and substrates were analysed on the basis of log-normal distribution curves. The results obtained showed that the ionization state of the PLP and GPha environment differs from that of GPhb. This divergence was interpreted in terms of tautomeric equilibria between some forms of the Schiff base of PLP and enzymic Lys-679. The ionic forms are slightly more predominant in GPha than they are in GPhb, so ionic and/or hydrogen-bonding interactions between the aromatic ring of PLP and GPha must be stronger than with GPhb. This confirms the purely structural role of the aromatic ring of the coenzyme. Binding of GPhb to AMP and Mg2+ results in the coenzyme adopting a similar state as in GPha. On the other hand, binding to IMP gives rise to no detectable changes in the tautomeric equilibrium of the coenzyme.

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Improvement of Road Safety through Appropriate Cargo Securing Using Outliers

Sustainability ◽

10.3390/su13052688 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2688

Author(s):

Martin Vlkovský ◽

Jiří Neubauer ◽

Jiří Malíšek ◽

Jaroslav Michálek

Keyword(s):

Normal Distribution ◽

Road Safety ◽

Statistical Evaluation ◽

Probability Distributions ◽

Statistical Comparison ◽

Vehicle Accidents ◽

Transport Experiment ◽

Log Normal ◽

The Individual ◽

Log Normal Distribution

The article focuses on evaluating a transportation experiment that intends to improve road safety by analyzing transport shocks that significantly affect the system of securing the load, vehicle, driver, and other aspects. Within Europe, improper or insufficient securing of loads causes up to 25% of all cargo vehicle accidents. Our transport experiment consists of eight rides of a Tatra truck. The measured values of shocks (acceleration coefficients) are statistically evaluated. Three hypotheses are established for these purposes. First, it is proven that the probability distributions of the shocks values differ statistically significantly among individual rides, namely in their shape and median value. Thus further statistical analyses are performed separately for the individual rides, axes, and the accelerometer locations. These analyses prove significant exceedances of the normatively set limits given by the EN 12195-1:2010 standard, which is potentially risky. Especially for the z axis and y axis, the set 20% limit was exceeded in 75.0% and 56.3% of cases, respectively. In the case of the x axis, the established 20% limit was practically not exceeded at all. The analysis of exceeding the permitted limits (the statistical evaluation of the second and third established hypothesis) is based on boxplots that graphically describe the individual rides, as well as on the found contaminated log-normal distribution of the values of the acceleration coefficients in the individual rides. The last hypothesis regarding exceeding the double value of the permitted limit is rejected. Methods of statistical comparison are used during data analysis. The probability distribution of acceleration coefficients is modeled using a contaminated log-normal distribution.

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A Universal Model for the Log-Normal Distribution of Elasticity in Polymeric Gels and Its Relevance to Mechanical Signature of Biological Tissues

Biology ◽

10.3390/biology10010064 ◽

2021 ◽

Vol 10 (1) ◽

pp. 64

Author(s):

Arnaud Millet

Keyword(s):

Elastic Modulus ◽

Normal Distribution ◽

Biological Tissues ◽

Force Microscopy ◽

Polymeric Gels ◽

Atomic Force ◽

Clear Explanation ◽

Log Normal ◽

Log Normal Distribution

The mechanosensitivity of cells has recently been identified as a process that could greatly influence a cell’s fate. To understand the interaction between cells and their surrounding extracellular matrix, the characterization of the mechanical properties of natural polymeric gels is needed. Atomic force microscopy (AFM) is one of the leading tools used to characterize mechanically biological tissues. It appears that the elasticity (elastic modulus) values obtained by AFM presents a log-normal distribution. Despite its ubiquity, the log-normal distribution concerning the elastic modulus of biological tissues does not have a clear explanation. In this paper, we propose a physical mechanism based on the weak universality of critical exponents in the percolation process leading to gelation. Following this, we discuss the relevance of this model for mechanical signatures of biological tissues.

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