Other Modification Methods

Mechano-activated modification uses a mechanical method, such as crushing, grinding, and friction, to change the lattice structure and crystal structure of the packing, increase system internal energy and temperature, promote particle melting and thermal decomposition, produce free radicals or ions, reinforce surface activity of fillers, promote chemical reactions between packing and other material or attachment 

In addition, ultraviolet light, infrared rays, corona discharge, and a plasma radiation halving method can also be carried out on particle surface modification. These methods do not need modifying agents, and are therefore beneficial for environmental protection. However, these technologies are complex and expensive. 

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Three other modifications of the standard conditions provide synthetically useful strategies for the preparation of dihydrofurans. One method, called the interrupted Feist-Benary reaction, utilizes milder reaction conditions to stop the final dehydration step. For example, Calter combined bromide 47 with dicarbonyl 48 to produce dihydrofuran 49 as a mixture of diastereomers. He examined the scope and diastereoselectivity of this process and applied this reaction toward the synthesis of the polycyclic core of the zaragozic acids. A method principally designed to yield practical syntheses of cyclic ketodiesters also furnished a dihydrofuran via a variation of the interrupted Feist-Benary reaction. ... 

The presence of allylic chlorines and tertiary chlorines and their influence on the thermal stability of PVC has now been established with some degree of confidence, and together they are considered to constitute the labile chlorine structures in the polymer. Numerous chemical modification methods involving the selective nucleophilic substitution of labile chlorines in PVC with other chemical moieties for identifying and quantifying labile structures have been reported in the literature. 

The other global method in common use is generally called the method of Qraejfe in western Europe and in the United States, and the method of Lobachevskii in the USSR. The first to state the principle was Dandelin, but Graeffe devised the algorithm, simple enough in itself, that is normally used. The method is widely known, and is described in many places. Hence, it will not be described here. But it is not widely known that the method is applicable, with rather trivial modifications, to solving transcendental equations. 

Unlike the other alternative methods, analytical expressions of partial derivatives are required and the Jacobian must be evaluated in the Newton-Raphson method. These requirements sometimes prove to be the undoing when the method is applied to complicated equations. Brown (B12) has developed a modification to the Newton-Raphson method, which requires only some of the partial derivatives to be calculated. We have tested Brown s method on our sample problems but have found that it actually required more computing time than the unmodified Newton-Raphson method. 

The procedure described for the preparation of l-(m-nitro-phenyl)-3,3-dimethyltriazene is the method of Elks and Hey,2 and the preparation of m-nitrobiphenyl is also a modification of their procedure. The other principal methods for the preparation of m-nitrobiphenyl are the decomposition of N-nitroso-w-nitroacetanilide in benzene 3 and the decomposition of alkaline m-nitrobenzenediazohydroxide in benzene.4 Other methods that have been reported include the decomposition of potassium ire-nitrobenzenediazotate in benzene with acetyl chloride,6 the decomposition of m-nitrobenzoyl peroxide in boiling benzene,6 the decomposition of benzenediazonium borofluoride in nitrobenzene 7 at 70°, and the reduction of 4-(3 -nitrophenyl)-benzenediazonium acid sulfate in boiling ethanol.8... 

Similar to the Fisher indole synthesis, reductive cyclization of nitro aromatics offers a powerful means of forming indoles. Reductive cyclization of ortho, 2 -dinitrostyrenes has occurred in many ways, by TiCl3, NaBH4-Pd/C, H2-Pcl/C, and other reductive methods.89 Corey and coworkers have used the Borchardt modification (Fe-AcOFI, sihca gel, toluene at reflux for the reductive cyclization of o-ji-dinitrostyrenes) to prepare 6,7-dimethoxyindole (Eq. 10.65) in a total synthesis of aspidophytine (see Schemes 3.3 and 3.4 in Section 3.2.l).89d... 

Remove excess reactants from the succinylated molecule by dialysis, gel filtration, or some other suitable method. The efficiency of amine modification may be assessed by use of the TNBS test for amines (Section 4.3, this chapter). A negative test for amines indicates complete succinylation. 

In 2003, Prior and others described methods for the extraction and analysis of hydrophilic and lipophilic antioxidants, using modifications of the ORAC procedure. These methods provide, for the first time, the ability to obtain a measure of total antioxidant capacity in the protein free plasma, using the same peroxyl radical generator for both lipophilic and hydrophilic antioxidants. This assay was also used to measure the total antioxidant capacity of guava fruit extracts (Thaipong and others 2006). 

Impregnation modification is an area of research that is relatively unexplored compared to other wood modification methods and there are undoubtedly many other systems that remain to be studied in the future. 

Besides the synthesis methods for porous membranes and their modification methods discussed above, other synthesis methods have been reported. These are outlined below. Preparation of dense membranes is discussed in Section 2.2. The other types are the so-called dynamically formed membranes which... 

Flue gas recirculation Flue gas recirculation, alone or in combination with other modifications, can significantly reduce thermal NO,. Recirculated flue gas is a diluent that reduces flame temperatures. External and internal recirculation paths have been applied internal recirculation can be accomplished by jet entrainment using either combustion air or fuel jet energy external recirculation requires a fan or a jet pump (driven by the combustion air). When combined with staged-air or staged-fuel methods, NO emissions from gas-fired burners can be reduced by 50 to 90 percent. In some applications, external flue-gas recirculation can decrease thermal efficiency. Condensation in the recirculation loop can cause operating problems and increase maintenance requirements. 

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