Mobil crystalline material

MALDI MCM-41 MCR MD ME MEM MI MPM MRI MS MVA Matrix-assisted Laser Desorption/Ionization Mobile Crystalline Material-41 Multivariate Curve Resolution Molecular Dynamics Matrix-enhanced Magnetic Force Micrscopy Multivariate Image Multiphoton Microscopy Magnetic Resonance Imaging Mass Spectroscopy Multivariate Analysis... 

Of particular interest is the material MCM-41, which has a structure consisting of highly ordered, two-dimensional (non-intersecting) hexagonal arrays of very uniform pores (Figure 6.1). MCM-48 is similar, but with a cubic structure. The acronym MCM has never been explained, and the suggestion Mobil Crystalline Material seems unlikely for a near-amorphous solid. MCM-41 is extremely porous, because up to 80% of the solid material can be empty space, and the pore walls have an enormous surface area. A value of twelve hundred square metres per gram, an area equivalent to more than a tennis court, would not be unusual ... 

In 1992, a new family of MPS was invented by The Mobil Corporation Laboratories named MCM-X (Mobil Crystalline Material Kresge et al. 1992). These ordered mesoporous silicas (OMSs) were initially developed for catalyst applications and were only later studied as a drug delivery technology. These silicas were synthesized from surfactant micelles under basic conditions. They have unique properties such as their pore diameter, high surface area (up to 1500 m /g), large pore volumes (up to 1.5cm /g), and silanol-rich surface which can be functionalized. Recently, the first pharmacompliant OMS materials have been developed. 

ASA Amorphous silica alumina FCC Fluid catalytic cracking HMCM Hydrogen form of MCM HY Hydrogen containing Y-type zeolite MOR Mordenite MCM Mobil crystalline material REY Rare earth Y SAHA Si02(silica)-Al203 (alumina) with 40 wt% HZSM-5 and 20 wt% ludox SBA Santa Barbara amorphous type material ... 

The concept of a characteristic reaction temperature must, therefore, be accepted with considerable reservation and as being of doubtful value since the reactivity of a crystalline material cannot readily be related to other properties of the solid. Such behaviour may at best point towards the possible occurrence of common controlling factors in the reaction, perhaps related to the onset of mobility, e.g. melting of one component or eutectic formation, onset of surface migration or commencement of bulk migration in a barrier phase. These possibilities should be investigated in detail before a mechanism can be formulated for any particular chemical change. 

Laboratory grade agents are typically colorless liquids or solids. Depending on the specific agent, liquids may be mobile, viscous, or even waxy in nature. Many solids are salts of the free-base liquid that are colorless to white to beige crystalline materials. In either state, these materials typically have little or no odor when pure. 

In solid-state electrodes the membrane is a solid disc of a relatively insoluble, crystalline material which shows a high specificity for a particular ion. The membrane permits movement of ions within the lattice structure of the crystal and those ions which disrupt the lattice structure the least are the most mobile. These usually have the smallest charge and diameter. Hence, only those ions that are very similar to the internal mobile ions can gain access to the membrane from the outside, a feature that gives crystal membranes their high specificity. When the electrode is immersed in the sample solution, an equilibrium is established between the mobile ions in the crystal and similar ions in the solution and the resulting potential created across the membrane can be measured in the usual manner. 

In the following decades, researchers in catalysis turned their efforts to controlhng molecular structure as well as size. The catalyst zeolite paved the way. In the late 1960s, researchers at Mobil Oil Co. were able to s)uithesize zeolite by deliberately designing and preparing the structure of catalysts at the atomic and molecular levels. The resulting nanostructured crystalline material (ZSM-5)—with a 10-atom ring and pore size of 0.45-0.6 nm—enabled the control of selectivity in petrochemical processes at the... 

When dealing with partially crystalline materials, such as those produced by milling, the effect of water uptake is intensified. The amorphous component likely absorbs greater quantities of water than its crystalline counterpart, leading to reduced Tg, increased molecular mobility, and both physical and chemical instability. 

Under conditions of step flow, the ability to grow good crystalline material is related to the mobility of the adatoms on the surface. These must be able to diffuse freely and find the proper crystal lattice sites for growth, wherever these are available. In this section, we discuss our calculations of the diffusion barriers on the Si (100) surface and the single-height steps. We shall restrict our discussion to the motion of adatoms even though there is considerable evidence that mass transport via dimer diffusion plays a role at high temperatures as well. ... 

The diffusion coefficients of the ions can be determined through time-of-flight techniques. For a liquid crystalline material between two ITO coated plates with an initial voltage V, a sudden increase in the voltage to Vi allows the ionic mean transit time t j and the ion mobility to be determined by the relations [69] ... 

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