scholarly journals III. A contribution to the study of the yellow colouring matter of the urine

1894 ◽  
Vol 55 (331-335) ◽  
pp. 394-407 ◽  
Keyword(s):  
Absorption Spectra ◽  
Spectroscopic Properties ◽  
Yellow Pigment ◽  
Chemical Methods ◽  
Distinctive Character ◽  
Yellow Coloration ◽  
Normal Urine ◽  
The Individual

The uncertainty which still surrounds the origin of a phenomenon so familiar as the yellow coloration of the urine bears eloquent testimony to the difficulties which beset the investigation, by ordinary chemical methods, of such substances as the urinary pigments, and to the importance of the part which the spectroscope has played in the acquisition of such knowledge of them as we possess. Indeed, our acquaintance with the individual pigments is proportional to the distinctive character of their absorption spectra, rather than to the time which has elapsed since they first attracted attention; and in not a few modern works doubt is thrown upon the very existence of a distinct yellow pigment, having negative spectroscopic properties, but to which normal urine owes its characteristic tint, the chief part in the coloration of the excretion being assigned to urobilin.

scholarly journals Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Wiebeler ◽  
Joachim Vollbrecht ◽  
Adam Neuba ◽  
Heinz-Siegfried Kitzerow ◽  
Stefan Schumacher
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Spectroscopic Properties ◽  
Absorption Bands ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Hartree Fock ◽  
Tauc Plot ◽  
Electrochemical Approach

AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands.

Spectra of the 1:1 and 3:1 solid complexes of coronene-TCNQ

1977 ◽  
Vol 55 (21) ◽  
pp. 3712-3716 ◽  
Author(s):  
Kim Doan Truong ◽  
André D. Bandrauk
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Absorption Spectra ◽  
Charge Transfer Band ◽  
Out Of Plane ◽  
The Individual ◽  
A Charge ◽  
Solid Complexes

Two new solid TCNQ complexes have been isolated, coronene–TCNQ 1:1 and 3:1. The infrared and electronic absorption spectra are presented for the two different stoichiometries. From these spectra we infer that the complexes are covalent in the ground state with a charge transfer band appearing at 730 nm. The out of plane vibrations of the individual molecules are noticeably perturbed upon complexation.

scholarly journals Brief Report: Absorption Spectra of Inclusion Bodies in β-Thalassemia

Blood ◽  
1965 ◽  
Vol 25 (1) ◽  
pp. 105-109 ◽  
Author(s):  
PHAEDON FESSAS ◽  
DIMITRIS LOUKOPOULOS ◽  
BO THORELL
Keyword(s):  
Absorption Spectra ◽  
Inclusion Bodies ◽  
Spectroscopic Properties

Abstract The spectroscopic properties of isolated or single erythroblastic and erythrocytic inclusions of homozygous β-thalassemia prove that these structures contain a hemoglobin-like component.

Urinary Crystal Growth: Effect of Inhibitor Mixtures

1981 ◽  
Vol 61 (4) ◽  
pp. 487-491 ◽  
Author(s):  
P. G. Werness ◽  
Jan H. Bergert ◽  
Karen E. Lee
Keyword(s):  
Crystal Growth ◽  
Calcium Oxalate ◽  
Inhibitory Activity ◽  
Calcium Oxalate Monohydrate ◽  
Growth Effect ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity ◽  
Measured Activity ◽  
Normal Urine ◽  
The Individual

1. The crystal growth inhibitory activity of mixtures of known inhibitors and of mixtures of known inhibitors with normal urine was determined in calcium oxalate monohydrate and hydroxyapatite seeded crystal growth systems. 2. The inhibitory activity of the mixtures was compared with the measured activity of the individual components of the mixtures. All mixtures had inhibitory activity equal to the sum of the activities of their components, with the exception of RNA/urine mixtures in the calcium oxalate monohydrate system. 3. RNA/urine mixtures had inhibitory activity toward calcium oxalate monohydrate crystal growth which was less than would be predicted from the activity of the RNA and of the urine which were added. This reduced inhibitory activity was shown to be due probably to hydrolysis of RNA by the ribonuclease activity normally present in urine. 4. The results of these experiments make it possible to determine quantitatively the contribution of various naturally occurring urinary crystal growth inhibitors to the total measured inhibition observed in urine.

Nucleotides as Structural Templates for The Self-Assembly of Quantum-Confined Cds Crystallites

1990 ◽  
Vol 206 ◽  
Author(s):  
Jeffery L. Coffer ◽  
Robin R. Chandler
Keyword(s):  
Computer Modeling ◽  
Absorption Spectra ◽  
Self Assembly ◽  
Physical Stability ◽  
Spectroscopic Properties ◽  
The Self ◽  
Modeling Studies ◽  
Quantum Confined ◽  
Cds Crystallites

ABSTRACTWe report here the use of nucleotides as stabilizers in the formation of quantum-confined (‘Q-size’) CdS, with the size and composition of the nucleotide exerting a significant effect on the resultant CdS structure. In general, CdS formed from equimolar Cd+2 and S2− (6 × 10−4 M) in the presence of a number of nucleotides yields clusters possessing similar absorption spectra but which differ significantly with respect to emissive behavior and overall physical stability. CdS/polynucleotide colloids (DNA, poly [A], poly[C]) exhibit strong trap luminescence and are stable on a timescale of months, but analogous CdS prepared from the mononucleotides ATP and AMP are virtually nonemissive and flocculate within hours, even upon stabilization at lower temperatures (5 to −60°C). In addition to their preparation and spectroscopic properties, the results of TEM, AFM, and computer modeling studies on these CdS/nucleotide colloids are discussed.

scholarly journals Modelling the Rayleigh match

2004 ◽  
Vol 21 (3) ◽  
pp. 477-482 ◽  
Author(s):  
P.B.M. THOMAS ◽  
J.D. MOLLON
Keyword(s):  
Absorption Spectra ◽  
Optical Density ◽  
Field Size ◽  
General Behavior ◽  
Anticlockwise Rotation ◽  
Peak Sensitivity ◽  
The Individual ◽  
Unique Match

We use the photopigment template of Baylor et al. (1987) to define the set of Rayleigh matches that would be satisfied by a photopigment having a given wavelength of peak sensitivity (λmax) and a given optical density (OD). For an observer with two photopigments in the region of the Rayleigh primaries, the observer's unique match is defined by the intersection of the sets of matches that satisfy the individual pigments. The use of a template allows us to illustrate the general behavior of Rayleigh matches as the absorption spectra of the underlying spectra are altered. In a plot of the Y setting against the red–green ratio (R), both an increase in λmax and an increase in optical density lead to an anticlockwise rotation of the locus of the matches satisfied by a given pigment. Since both these factors affect the match, it is not possible to reverse the analysis and define uniquely the photopigments corresponding to a specific Rayleigh match. However, a way to constrain the set of candidate photopigments would be to determine the trajectory of the change of match as the effective optical density is altered (by, say, bleaching or field size).

Spectrophotometric study of the effect of tensides on triphenylmethane dyes

1982 ◽  
Vol 47 (3) ◽  
pp. 776-784 ◽  
Author(s):  
Vlasta Škarydová ◽  
Ludmila Čermáková
Keyword(s):  
Absorption Spectra ◽  
Spectrophotometric Study ◽  
Triphenylmethane Dyes ◽  
Experimental Conditions ◽  
Bromopyrogallol Red ◽  
Strong Electrolytes ◽  
The Individual ◽  
Triton X

The effect of cation-active tenside 1-carbethoxypentadecyltrimethylammonium bromide (Septonex) on the absorption spectra of selected triphenylmethane dyes, eriochromcyanine R and bromopyrogallol red, was studied. The effect of the micelle aggregates of the tenside on the spectrophotometric characteristics of the individual dissociated forms of the dyes was demonstrated and the influence of strong electrolytes (NaCl, NaNO3) was studied. The interaction of both dyes with the micelle form of the nonionic tenside Triton X-100 was studied under similar experimental conditions.

scholarly journals Tetranucleotides as a scaffold for diporphyrin arrays

2006 ◽  
Vol 78 (11) ◽  
pp. 2003-2014 ◽  
Author(s):  
Imenne Bouamaied ◽  
Leslie-Anne Fendt ◽  
Markus Wiesner ◽  
Daniel Häussinger ◽  
Nicolas Amiot ◽  
...  
Keyword(s):  
Excited State ◽  
Emission Spectra ◽  
Building Blocks ◽  
Spectroscopic Properties ◽  
H Nmr ◽  
Base Form ◽  
Tetraphenyl Porphyrin ◽  
Cotton Effects ◽  
Band Absorption ◽  
The Individual

The incorporation of porphyrin-substituted nucleosides into tetranucleotides using phosphoramidite chemistry on solid support is reported. Both diphenyl and tetraphenyl porphyrin nucleosides were used as building blocks. This method allows the synthesis of chiral homo- and heteroporphyrinic arrays, where the composition and thus the physical properties of the array can be modulated simply by reprogramming the DNA synthesizer. The porphyrin arrays are initially isolated in the free-base form. Remetallation to give the zinc-porphyrins can be achieved using standard procedures in solution. The UV-vis spectra of the arrays are reproducible by a superposition of the absorbance spectra of the individual porphyrins, indicating an undisturbed electronic ground state of the porphyrins in the arrays. The same is true for the steady-state emission spectra of the homoporphyrinic arrays, which are not influenced by the presence of the nucleotide strand. In the mixed porphyrin arrays, large differences in the excited-state properties compared to an equimolar mixture of the building blocks are observed by means that the emission of the diphenyl porphyrin moiety is quenched to a large extent, and the overall emission is dominated by the tetraphenyl porphyrin. The covalent connection of the porphyrins via the DNA-derived backbone therefore substantially alters the excited-state and energy-transfer properties of mixed porphyrin systems. The circular dichroism (CD) spectra show induced negative cotton effects in the region of the porphyrin B-band absorption, which is due to the attachment of the chromophores to the chiral oligonucleotide backbone. Addition of a complementary tetra-adenosine did not alter any of the spectroscopic properties, neither in chloroform nor in acetonitrile solutions. Therefore, it can be concluded that no duplex is formed, which is corroborated by 1H NMR spectroscopy.

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