Nitrogen modulation

Systematic modification of the sulfanilamide molecule in order to maximize the hypoglycemic activity led to the observation that the sulfonamide is best replaced by a sulfonylurea function. Modification on both the aromatic ring and the substituent on the terminal nitrogen modulates the activity of the products. ... 

Three years later, Pursch et al. reported on the improvement of this modulator using liquid nitrogen instead of CO2 for cryo-focusing [48]. They highlighted the efficiency in terms of modulation of highly volatile components such as propane and butane. The nitrogen modulator is illustrated in Figure 14. 

For instance, nitrogenation modulates the crystal structures, saturation magnetization (Ms), and Curie temperature (7c) of Fe films [4, 5], substantially. An addition of a small amount of N raises the Ms value of the a"-FeiftN2 phase by 25 % of that of pure Fe (2.22 b)- Further doping of N lowers the Ms value associated with crystal structure transition from s, y, to the paramagnetic phase of amorphous FeN [6]. Nitrogenation also raises the Ms value and the Tc of rare earth I-ferromagnet (Co and Fe) considerably [7]. The Ms of the R(Fe, Co) alloys is increased by 30-40 % relative to their parent alloys [7]. 

Chemical off—on switching of the chemiluminescence of a 1,2-dioxetane (9-benzyhdene-10-methylacridan-l,2-dioxetane [66762-83-2] (9)) was first described in 1980 (33). No chemiluminescence was observed when excess acetic acid was added to (9) but chemiluminescence was recovered when triethylamine was added. The off—on switching was attributed to reversible protonation of the nitrogen lone pair and modulation of chemically induced electron-exchange luminescence (CIEEL). Base-induced decomposition of a 1,2-dioxetane of 2-phen5l-3-(4 -hydroxyphenyl)-l,4-dioxetane (10) by deprotonation of the phenoHc hydroxy group has also been described (34). 

Membrane separation Medium to high purity Na, 95to 99.9% Small typical module produces 855 scfh at I75lb/in and 77°F Can use plant air as air source simple and safe to operate stable output maybe economical for low-capacity medium- to high-purity requirements excellent when some oxygen is required with the nitrogen temperature and pressure sensitive... 

The efficacy of the phenothiazines for the treatment of various psychoses led to extensive synthetic programs aimed at modulation of the biologic spectrum of these molecules. As seen elsewhere, much of this work has centered on changes of the nature of the atoms that constitute the center ring. Thus, for example, it has proven possible to replace the nitrogen atom of the phenothiazine by carbon while maintaining neuroleptic activity. 

Dimefoylhydrazine, foe fuel used in foe Apollo lunar descent module, has a molar mass of 60.10 g/mol. It is made up of carbon, hydrogen, and nitrogen atoms. The combustion of 2.859 g of the fuel in excess oxygen yields 4.190 g of carbon dioxide and 3.428 g of water. What are foe simplest and molecular formulas for dimefoylhydrazine ... 

Click Coached Problems for a self-study module on structures of nitrogen oxides. 

It should be noted that there is a considerable difference between rotational structure narrowing caused by pressure and that caused by motional averaging of an adiabatically broadened spectrum [158, 159]. In the limiting case of fast motion, both of them are described by perturbation theory, thus, both widths in Eq. (3.16) and Eq (3.17) are expressed as a product of the frequency dispersion and the correlation time. However, the dispersion of the rotational structure (3.7) defined by intramolecular interaction is independent of the medium density, while the dispersion of the vibrational frequency shift (5 12) in (3.21) is linear in gas density. In principle, correlation times of the frequency modulation are also different. In the first case, it is the free rotation time te that is reduced as the medium density increases, and in the second case, it is the time of collision tc p/ v) that remains unchanged. As the density increases, the rotational contribution to the width decreases due to the reduction of t , while the vibrational contribution increases due to the dispersion growth. In nitrogen, they are of comparable magnitude after the initial (static) spectrum has become ten times narrower. At 77 K the rotational relaxation contribution is no less than 20% of the observed Q-branch width. If the rest of the contribution is entirely determined by... 

An internally-staged, gas-permeation module is used for the oxygen enrichment of air, using the flow arrangement shown in Fig. 5.206. Enrichment depends on differing membrane permeabilities for the oxygen and nitrogen to be separated. The permeation rates are proportional to the differences in component partial pressures. 

The residue-containing eluate from the GPC step is evaporated and analyzed by GC with nitrogen/phosphorus detection (NPD) (Modules D3 and D4) or mass spectrometry (MS) detection. For GC with electron capture detection (ECD) (Module Dl), the GPC eluate requires an additional cleanup on a small silica gel column. 

Figure 10 shows the dependency of the modulation index on the measurement gas cell concentration (%v/v), assuming dilution by nitrogen gas, at a pressure of 1 Bar and a temperature of 20 °C. This shows that there is a significant non-linearity in the modulation index response, particularly at higher CO2 gas concentrations in the measurement cell. As before, an optical filter bandwidth of 100 nm was assumed. 

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