Depression measurement

Boiling-point elevation and freezing-point depression measurements have demonstrated that at all concentrations in THF and at low concentrations in ether (up to 0.1M) Grignard reagents prepared from alkyl bromides and iodides are monomeric, that is, there are few or no molecules with two magnesium atoms. Thus, part of the Schlenk equilibrium is operating... 

Depression is a common, serious, sometimes fatal illness that is chronic and recurrent in nature, impairs family life, reduces social adjustment, and is a burden on the community (Klerman and Weissman, 1992). This disease chronicity magnifies hoth its societal impact and its economic burden. It has been estimated that more than 17% of the disability associated with mental disorders is the result of depressive disorders (Rosenbaum and Hylan, 1999), and that the global burden of depression, measured in terms of disability-adjusted life years, will rank second only to ischaemic heart disease by the year 2020 (Murray and Lopez, 1996). 

A unitless correction factor that relates the relative activity of a substance to the quantity of the substance in a mixture. Activity coefficients are frequently determined by emf (electromotive force) or freezing-point depression measurements. At infinite dilution, the activity coefficient equals 1.00. Activity coefficients for electrolytes can vary significantly depending upon the concentration of the electrolyte. Activity coefficients can exceed values of 1.00. For example, a 4.0 molal HCl solution has a coefficient of 1.76 and a 4.0 molal Li Cl has a value of... 

D haenen HA, Bossuyt A Dopamine D2 receptors in depression measured with single photon emission computed tomography. Biol Psychiatry 35 128-132, 1994 Di Costanzo E, Schifano E Dthium alone or in combination with carbamazepine for the treatment of rapid-cycling bipolar affective disorder. Acta Psychiatr Scand 83 456-459, 1991... 

The final colligative property, osmotic pressure,24-29 is different from the others and is illustrated in Figure 2.2. In the case of vapor-pressure lowering and boiling-point elevation, a natural boundary separates the liquid and gas phases that are in equilibrium. A similar boundary exists between the solid and liquid phases in equilibrium with each other in melting-point-depression measurements. However, to establish a similar equilibrium between a solution and the pure solvent requires their separation by a semi-permeable membrane, as illustrated in the figure. Such membranes, typically cellulosic, permit transport of solvent but not solute. Furthermore, the flow of solvent is from the solvent compartment into the solution compartment. The simplest explanation of this is the increased entropy or disorder that accompanies the mixing of the transported solvent molecules with the polymer on the solution side of the membrane. Flow of liquid up the capillary on the left causes the solution to be at a hydrostatic pressure... 

In the calorimetric approach, it is necessary to know the heat of fusion of the totally crystalline polymer. This can be obtained from melting-point depression measurements, as described in the following section. The basic idea depends on the fact that the melting temperature is independent of the size of the system, since it is an intensive property. The extent to which it is depressed by the presence of solvent can be used to calculate a heat of fusion characteristic of the crystallites, irrespective of how many are present. This is therefore the heat of fusion of the 100% crystalline polymer. The fractional crystallinity in an actual sample is then the ratio of its calorimetrically measured heat of fusion per gram to that of the 100% crystalline polymer. For example, if the actual polymer has a heat of fusion of 7 cal per gram, and the 100% crystalline polymer a heat of fusion of 10 cal per gram, then the fractional crystallinity is 0.7, and the percentage crystallinity is 70%. 

Characterization of the AlMe3—MeCl System by NMR. It appears that the AlMe3 in methyl chloride system has not been investigated previously by NMR spectroscopy. In related research by other workers, freezing point depression measurements of AlMe3 in benzene solution indicated the predominant presence of dimers—i.e. (13) ... 

D Haenen HA, Bossuyt A (1994) Dopamine D2 receptors in depression measured with single photon emission computed tomography. Biol Psychiatry 35 128-132. 

Klimke A, Larisch R, Janz A, Vosberg H, Muller-Gartner HW, Gaebel W (1999) Dopamine D2 receptor binding before and after treatment of major depression measured by [123I]IBZM SPECT. Psychiatry Res 90 91-101. 

The mechanism of extraction in tracer rare earth concentrations using HDEHP was investigated by Peppard et al. (7,8,9). Freezing-point depression measurements of toluene by the addition of HDEHP showed that HDEHP is dimeric in solution (9). On the basis of all their findings... 

Freezing point depression measurements furnish another convenient approach to determine the activity of the solvent. Eqs. (3.13.1,4) may be taken over without change because we have not had occasion to refer to the ionic dissociation process. 

Pentaethoxyuranium is a dark-brown, mobile liquid with a density of 1.71 g/cm3 at 25°.2 The liquid boils at 123° at 0.001 torr and is thermally stable below 170°. The compound is readily hydrolyzed and is oxidized by dry oxygen (in the presence of excess NaOC2Hs) to hexaethoxyuranium.2 Pentaethoxyuranium has a dimeric structure at room temperature as determined by freezing-point depression measurements in benzene.2 It is miscible with ethanol, diethyl ether, benzene, petroleum ether, ethyl acetate, carbon tetrachloride, chloroform, carbon disulfide, pyridine, dioxane, and nitrobenzene. The proton magnetic... 

Ohm s law R = EH, where R is resistance, E is voltage, and / is current, roughness - microscopic peak-to-valley distances of film-surface protrusions and depressions, measured in angstroms. 

The Nitryl Ion, NO The stem nitric acid-sulfuric acid, commonly known as mixed acid, is the most important nitrating medium from a practical standpoint and is probably also the best understood. There is a large body of evidence that supports the belief that nitric acid exists in strong sulfuric acid as the nitryl ion, N02 . From freezing-point depression measurements, the Van t Hoff t factor (the number of particles generated by one molecule of solute) of nitric acid in sulfuric acid is found to be 4, which indicates that the ionization of nitric acid can be represented by the equation... 

What is formed when a solution for a freezing-point depression measurement freezes ... 

Compare the experimental molecular weight of aspirin as calculated from freezing-point depression measurements with that calculated from NaOH titration data. Explain the difference. 

The state of cure of the phases in a blend can be determined from changes in the magnitude of the damping peaks (Runt and Martynowicz, 1985) and from freezing-point-depression measurements on swollen networks. Keith and... 

Thermocouples may be used to determine freezing-point depression directly by using a freezing mixture of the pure solvent as the reference temperature. It should, however, be remembered that the accuracy of a temperature depression measured in this way will be determined by the stability of the reference temperature. Should a freezing mixture of pure solvent be difficult to maintain, either because the heat of fusion is low or because the solvent is easily contaminated, it is preferable to use an alternative reference such as an ice-water mixture. 

Finally, melting point depression measurements have been conducted on several symmetrically substituted polysiloxanes, specifically the dimethyl, diethyl, di-n-propyl, and diphenyl polymers. Interpretation of such experimental results yields entropies of fusion. Although it is difib-cult to extract a reliable configurational entropy from this quantity, such results could help elucidate the configurational characteristics of the chains thus investigated. ... 

The normalized residual stress depression measured for crazed HIPS as a function of (fixed) strain. 

Where well preserved, the protegula of the Late Devonian linguloids are easily detectable in the umbonal region of the valve by their distinct morphology. Although the protegulum is a convex structure, it frequently possesses a shallow, circular central depression measuring from 27 to 32 pm in diameter (Fig. lO.lD-G), bordered at its periphery by a thickened rim. 

Bench CJ, Friston KJ, Brown RG et al (1993) Regional cerebral blood flow in depression measured by positron emission tomography the relationship with clinical dimensions. Psychol Med 23 579-590... 

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