N absorption

Aufnahme-fahigkeit, /. absorbability, absorptivity, absorbing power capacity. -ge-Bchwindigkeit, /. absorption rate, -kolbeu, m. absorption flask, -pipette,/, a pipet calibrated to take up a definite volume. Cf. Ausflusspipette. -vermogen, n. absorptive power. 

Figure 15-3 shows the optical absorption spectrum of a MEH-PPV/C60 film with different C, content compared to the optical absorption spectrum of the components alone. The peak at 2.5 eV is identified as the n-n absorption of MEH-PPV and is clearly observed along with the first dipole-allowed transition in C(l0 (at 3.75 eV). The spectrum is a simple superposition of the two components. Further-... 

An interesting feature of the i.r. spectra of these compounds was that the intensity of the C=N absorption was relatively low and, to account for this, an interaction of the type shown with (1) was suggested. With phos-... 

Ravindranath, V. and Chandrasekhara, N., Absorption and tissue distribution of curcumin in rats, Toxicology, 16, 259, 1980. 

The 7t scale of solvents (Kamlet-Taft scale) is intended to represent the solute-solvent interactions in the absence of strong forces such as hydrogen-bonding or dipole-dipole interactions. It is based on the n to n absorption of a series of seven solutes (six uitroaromatics, such as 4-uitroanisole, A, A -diethyl-3-nitroaniline, 1-ethyl-4-uitrobeuzeue, etc., aud 4-dimethylamiuobenzophenone) [51-53]. 

As reported by Nelissen [58], unreacted carbodi-imides (Stabaxol I, P and P100), used as hydrolysis stabilisers in e.g. polyesters, are readily detected by IR analysis on the basis of the —N=C=N—absorption at 2140 cm 1, but without further discrimination within... 

The failure to observe photosubstitution in the presence of a sensitizer in which the latter is the principal absorber, the invariance of product quantum yield with wavelengths shorter than 350 nm (onset of n -> -n absorption), and the observation that chloride and bromide ions (known to catalyze S-+T intersystem crossing) strongly diminish the quantum yields of these reactions, strongly points to the lowest excited ir- n singlet state as the reactive species in these transformations. Excitation into the n->ir absorption band results in little product formation. A triplet state may, however, be involved in the photoamination of nitrobenzene.a41)... 

As discussed before, a,P-unsaturated ketones are usually reduced to saturated ketones in isopropyl alcohol as solvent, the reaction proceeding via the enol after H-abstraction by the carbonyl group. When some selected a,p-enones are irradiated in their n-n absorption band (i.e. excitation... 

A typical photochemical isomerization of the azobenzene amphiphile was found in an ethanol solution. A trans isomer converted to a cis isomer with ultraviolet irradiation. Back reaction from cis to trans was accelerated when a weak n-n absorption band of the cis isomer at ca.450nm was excited (Figure 21a). An alternative irradiation of uv and visible light to the ethanol solution gave reversible changes of the ji-ji transition between 355nm and 325nm attributed to the trans and cis isomers, respectively. 

In some heterocyclic compounds such as acridine, the n-n absorption band is difficult to distinguish from the much more intense n-n absorption bands. 

These results suggest various possibilities for increasing the efficiency of N absorption and assimilation. The fact that the NH4+ and NO3 transport systems... 

Figure 3, Triplet EPR spectra of TCP 10 M) in CH Cl-CH OH recorded at about 10 K. Microwave power 0,5 mW field modulation 20 G (100 kHz) excitation with square wave modulated (83 Hz) light of an argon laser (514.5 am 0.5 W). (a) No addition (b) with NaCl (- 5 x 10 M) and (c) with KCl ( 5 X 10 N). Absorption and emission peaks have been labeled A and E. respectively.

Spasmolytics. N-Butylscopolamine (p. 104) is used for the relief of painful spasms of the biliary or ureteral ducts. Its poor absorption (N.B. quaternary N absorption rate <10%) necessitates parenteral administration. Because the therapeutic effect is usually weak, a potent analgesic is given concurrently, e.g., the opioid meperidine. Note that some spasms of intestinal musculature can be effectively relieved by organic nitrates (in biliary colic) or by nifedipine (esophageal hypertension and achalasia). 

Lomef/oxac/n- Absorption is rapid. Following coadministration with food, rate of absorption is delayed, and the extent of absorption (AUC) is decreased by 12%. Steady-state concentrations are achieved within 48 hours of initiating once daily dosing. Mean renal clearance is 145 mL/min in subjects with normal renal function, which may indicate tubular secretion. In healthy elderly volunteers, plasma clearance was reduced by about 25% and the AUC was increased by about 33%. Adjustment of dosage is necessary. 

The infrared spectra of dihydrodiazepine bases show bands at 3150-3190 cm" (NH), no normal C=N absorption, and a characteristic absorption between 1500 and 1600 cm" [67JCS(C)2400 76IJC(B)1004]. 

Substituted anhydro-5-thiolo-l,2,3,4-oxatriazolium hydroxides (5) display a strong C=S absorption at 1365-1375 cm <74JCS(Pi)645>, while anhydro-5-amino-l,2,3,4-oxatriazolium hydroxides (6) show a strong C=N absorption at 1675-1680 cm <79JCS(Pi)74l>. 

Interaction of two chromophores exhibiting allowed (strong) n-n absorption bands splits the excited state into two energy levels with the energy gap 2VSj (Davydov splitting), Figure 12. 

Examination of the optical spectrum of the filtered purple solution gave a structured absorption band with maxima at 514 and 543 nm. This position is remarkably close (566 nm) to the n-n electronic transition predicted by Davis and Goddard for the parent system H2N=N. As expected for an n-n transition, the position of the absorption maximum is solvent dependent. In dichloromethane solution, A,i ax is 541 nm, in 2-propanol it is 526 nm. The blue shift of 15 nm is completely consistent with the n-n absorptions of isoelectronic carbonyl compounds. 

The ultraviolet absorption spectra of ketones are characterized by a low intensity n -n absorption band in the 270-300 nm region, and a high intensity... 

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