Reaction Hertz

Hertz—Knudsen—Langmuir equation, 21 hexammine nickel perchlorate, reaction + H20, 84 holes, 5, 32... 

Fig. 5 b. Polarized spectrum obtained in reaction of 1 (0.2 M) in methyl phenylacetate at 140 Chemical shifts are in hertz downfield from solvent CH3... 

It was first obtained by Hertz [67] who proposed its use as an explosive, since (in the authors opinion) it develops greater explosive strength that PETN but is less sensitive. Tollens and Apel [68] have prepared the initial alcohol (m.p. 156°C) resulting from the reaction of acetone with formaldehyde in the presence of calcium hydroxide, to which they attributed the structure of an enneaheptitol anhydride without, however, determining which hydroxyl groups were dehydrated. 

Although the substitution processes afforded by the action of the primarily discharged anion of an inorganic salt upon an organic body are to be included among the simpler reactions, the results obtained so far in this domain have been very scanty, especially in regard to aromatic substances. The above-mentioned investigations of Elbs and Hertz, as well as those of Forster and Mewes on the electrolytic preparation of iodoform,... 

Schauble, J. H. and Hertz, li., A reinvestiga-tion of the Mannich reaction of 4-nitro- and... 

Flaloform reaction, 273, 311, 335 Halogen exchange, 119 Halogenation of alkanes, 56 of arenes, 202 Halohydrin, 100 Hammond principle, 209 Hard bases, 121 H-bonding, 257, 333, 401 H-counts in nmr, 241 Heat of combustion and stability, 90 Hell-Volhard-Zelinsky reaction, 340 Hemiacetal, 317 Hertz, 230... 

Carstensen H, Nolte H, Hertz H. Teniposide-induced hypersensitivity reactions in children. Lancet 1989 2(8653) 55. 

The speed of a reaction between molecules in a film and those in the underlying solution depends on the rate of approach of the latter to the interface. There are two ways of exactly evaluating the latter, one depending, as we have seen in Section II, on the use of the gas laws and the other using the diffusion coefficient of the molecules in solution. The former method w as suggested by Fosbinder and Rideal (16), who used the Hertz expression,... 

HTLC HTLV III HTN HTP HTR HTVD HUIFM HUR HUS HV H V HW hwb Hx Hz HZ HZO human T-cell leukemia virus human T-cell lymphotrophic virus type III hypertension House-Tree-Person test acute hemolytic transfusion reaction hypertensive vascular disease human leukocyte interferon meloy hemolytic uremic syndrome hemolytic uremic syndrome hallux valgus has voided hemigastrectomy and vagotomy heparin well housewife hot water bottle history hospitalization Hertz herpes zoster herpes zoster ophthalmicus... 

The work of Forbes and Battersby [46] is an integrated study of the relations among the chemical structures of the dialkyl phosphites, their adsorption on and reaction with iron, and their behavior in four-ball bench testing of lubricant additive effectiveness. The four-ball data in Table 11-17 for solutions of additive in white oil show that both the wear/load index (mean Hertz load) and the initial seizure load are critically responsive to concentration, with a strong effect when the concentration increases from 0.01 to 0.04 molal (0.031% to 0.124% P). The initial seizure load is an uncomplicated criterion with a straightforward interpretation, whereas the wear/load index is contrived, both in concept and performance. The low-load 50 minute wear data show inconsistencies in the influence of additives that have not been explained. 

Two approaches can be employed to take into account the effect of temperature on the decomposition rate. One of them (dominating in solid-state kinetics) is based on the Arrhenius idea that only active particles are involved in a reaction, whose fraction depends exponentially on the temperature and the height of the energy barrier in the reaction course, and the other (advanced by Hertz and further developed by Langmuir), on the dependence of the maximum vaporiz ation rate of a substance from a free surface on its equilibrium vapour pressure. Both approaches fit equally well the exponential dependence of the decomposition rate on temperature, which was substantiated thermodynamically by van t Hoff (see below). Both these approaches are considered in more detail below. 

Modification of the Hertz-Langmuir Equation as Applied to Decomposition Reactions... 

Consider first the form of the Hertz-Langmuir equation for the particular case of decomposition of reactant R in vacuum into gaseous products A and B in the reaction... 

An example of determining the corrosion rate by this method is shown in Figure 20.12 (Behrens 1987). However, for very small corrosion currents that are independent of potential in some ranges (e.g., in passive metals), this method cannot be used to determine the corrosion rate. Nor is the method applicable when nontransfer-related part reactions occur, such as when the corrosion current is dependent on diffusional processes at the specimen surface. Also, the constant B can be time-dependent when dense protective films form, which further restricts the licability of the metal (Evans 1965 Hertz 1968). 

An alternative approach for modelling chemical kinetics can be realized by the use of neural networks which serve as universal approximators (Hertz el al [4]). Neural models describe only relations between measurable quantities which in the case of the example above can be the slow-varying concentration of hydrobromic acid. Within the framework of neural networks we have to model the relationship between concentration and reaction rate of hydrobromic acid... 

The rate constants reported by Hertz for some of the exchange reactions are very high and close to the rate limit for diffusion control ... 

The word ultrasound has become common knowledge due to the widespread use of ultrasound scanning equipments in medical applications. Ultrasound refers to sound waves having frequencies higher than those to which the human ear can respond (p, > 16 KHz) (Hz = Hertz = cycles per second). High frequency ultrasound waves are used in medical equipments. The ultrasound frequencies of interest for chemical reactions (about 20-100 KHz) are much lower than those used for medical applications, but the power used is higher. 

Hertz studied the effect of vitamin A deficiency on the healing of experimental fractures in the rat. He found a delay in the absorption of the fracture hematoma. There was no effect on the inflammatory reactions on the part of the cambial layer of the periostemn, the endosteum, and the marrow, all of which appeared to pass normally through their various phases. The only direct effect of the deficiency appeared to be a poor development of cartilage in the fracture callus. 

---