Sinusoidal channels

FIGURE 6.6 Biotransformation and liver structure. Liver cells called hepatocytes are wedged between blood channels (sinusoids) and bile canals. Foreign chemicals that have been taken up into the bloodstream diffuse down their eoncentration gradients out of the bloodstream and into hepatocytes. There they are subject to biotransformation by Phase I and Phase II enzymes. The structurally transformed chemicals move out of the hepatocyte, entering either the blood sinusoid (smaller chemicals) or the bile canal (larger chemicals) or both (chemicals of intermediate size). Biotransformed chemicals that enter the bloodstream are eliminated by the kidneys. Biotransformed chemicals that enter the bile canals are eliminated in the feces. (Reprinted with permission from David Shier, Jackie Butler and Ricki Lewis, Hole s Human Anatomy and Physiology, 7th ed. [Dubuque Wm. C. Brown, 1996], 696.)... 

In the as-synthesized MFI-crystals the tetrapropylammonium (TPA) ions are occupying the intersections between the straight (parallel) and the sinusoidal channels of the zeolite, thus providing an efficient pore filling. The detailed structure of as-synthesized MFI-TPA has been elucidated by X-ray single crystal analysis (ref. 3). Also the combination tetrabutyl-Ztetraethylammonium can be applied as template in MFI-synthesis. A 1 1 build-in is found then (Fig. 1). When only tetrabutylammonium is available as template, the MEL (ZSM-11) lattice is formed with another distance between the channel intersections. 

Figure 2.18 Different channel shapes for which flow distributions have been computed, a zigzag (upper left), a sinusoidally curved (upper right) and a converging-diverging channel (bottom).

In the articles cited above, the studies were restricted to steady-state flows, and steady-state solutions could be determined for the range of Reynolds numbers considered. Experimental work on flow and heat transfer in sinusoidally curved channels was conducted by Rush et al. [121]. Their results indicate heat-transfer enhancement and do not show evidence of a Nusselt number reduction in any range... 

Figure 2.27 Streamline patterns in a channel with sinusoidal walls (left) and Nusselt number as a function of Reynolds number for the same channel (right), taken from [120]. For comparison, the triangles represent the Nusselt number obtained in parallel-plates geometry.

MCM-22 zeolite (IZA code MWW) presents a novel and original structure which is composed of two independent pore systems a 2-dimensional, sinusoidal, 10-ring intralayer channels system and an interlayer system with 12-ring supercages, accessible through 10-ring apertures [1], This unique pore structure of the aluminosilicate MCM-22 zeolites makes them interesting catalysts for a wide variety of acid-catalyzed reactions, e.g. alkylation of aromatics [2],... 

The present work deals with the study of the liquid phase phenol alkylation by (-butanol over the three types of catalysts derived from MWW-precursor MCM-22, MCM-36 and ITQ-2. It was assumed that by pillaring and/or delamination the contribution of acid sites located on the hemicages will increase and it could be evidenced during the alkylation of phenol by (-butanol, process involving large reaction intermediates and products which are difficult to be accommodated within sinusoidal channels. The reaction pathway involves many parallel and/or successive steps, the main reactions being O-alkylation and C-alkylation. The catalytic activity and selectivity of these materials are discussed. A general scheme of the process is proposed on the basis of the structural and acidic features of the catalysts. 

In agreement with this, the analysis of the products forming during the alkylation over MCM-22 samples at different reaction time showed that about 80-90 wt. % of the recovered material is adsorbed on the external surface (phenol, o-TBP and p-TBP), whereas only about 10-20 wt.% is formed inside the zeolite ( coke constituted by p-TBP, naphthalenes, 9,10-dihydro-phenanthrene and acenaphthylene). Coke molecules could be formed in both supercages and sinusoidal channels. However, in the large supercages they would be converted into bulkier compounds, which is not the case. Therefore they are most likely located in the sinusoidal channels. 

The typical form of proarrhythmia caused by the type Ic antiarrhythmic drugs is a rapid, sustained, monomorphic VT with a characteristic sinusoidal QRS pattern that is often resistant to resuscitation with cardioversion or overdrive pacing. Some clinicians have had success with IV lidocaine (competes for the sodium channel receptor) or sodium bicarbonate (reverses the excessive sodium channel blockade). 

Figure 4.5 View into the pores of the ZSM-5 (MFI) structure along the straight channels (left) and along the sinusoidal channels (right). (Reprinted from D. Kern, N. Schall, W. Schmidt, R. Schmoll, J. Schurtz, Winnacker-Kuchler Chemische Technik, Prozesse und Produkte, Vol. 3, iliciumverbindungen, pp. 849-850. Copyright 2005. With permission from Wiley-VCH.)...

A very-low-frequency sinusoid was superimposed on these spectral lines owing to channeling. This comes about by reflections from the window surfaces that contain the sample gas. These often result in a spike on the interferogram, which produces a superimposed sinusoid on transforming. Rather than removing the sinusoid from the entire data set, we fitted a smooth curve to the base line of each isolated set of lines treated. 

The liver contains an enormous number of hepatocytes that perform the various functions noted above. The hepatocytes are contained within minute units known as hepatic lobules, in which the cell layers (which are one or two cells thick) are in contact with networks of minute blood channels - the sinusoids - which ultimately join the venous capillaries. Capillaries carrying blood from the hepatic artery and the portal vein empty separately into the sinusoids. The walls of sinusoids and liver cells are incomplete, and blood is brought into direct contact with the hepatocytes. 

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