Resistance, Redistribution and Investor-Friendliness

Poor communities sometimes resist private investment and destroy economic surplus even if the government has the willingness and ability to redistribute. We interpret such acts of resistance as demands for redistribution: Destruction contains credible information about how affected groups value surplus, which helps the government in implementing the optimal redistribution policy. Destruction is increasing in the extent of political marginalization of the affected group. While resistance has informational value, it has two distinct costs: it directly reduces surplus and also reduces the investor’s incentives to create surplus. The government uses a tax/subsidy on the investor to maximize weighted social surplus, and we show that the possibility of destruction may force the government to be too soft in its negotiations with the investor. We discuss conditions under which the government should ban resistance or should allow resistance but compensate the investor for its losses incurred in order to enhance social welfare

N-heterocyclic iminium ions catalyzed Friedel–Crafts type alkenylation of arenes with alkynes: A metal free and solvent free approach

The current manuscript elucidates a pioneering approach for achieving regioselective Markovnikov-type hydroarylation of alkynes, without the use of any metal catalysts. The aforementioned process is expedited through the implementation of 2-amino-perimidinium bromide and TFA as catalyst systems and is executed in the absence of solvents, thereby expanding the range of substrates (including arenes and alkynes). The correlation between the stoichiometric reactions and experimental data substantiates the postulated reaction mechanism

Pyrophyllite - a potential material for application in tri-axial porcelain systems

Pyrophyllite is largely an overlooked raw material available in huge quantities in nature. This is mainly due to the fact that other comparable aluminosilicate raw materials like china clay are available in much purer form. However, fast depleting reserves of standard raw materials necessitated renewed attention on so far sparingly used raw materials like pyrophyllite. Investigative work on pyrophyllite is also insignificant in comparison to other ceramic raw materials. Available information are scattered and it is felt that a comprehensive review is needed for effective dissemination of the information already generated and available in the public domain. In the present article salient points on the material including structure, chemistry of heating and possibility of future applications particularly in triaxial ceramic system is discussed. In a case study one Indian pyrophyllite was incorporated (15%) in a triaxial body composition replacing both china clay and quartz. The changes in fired properties was tried to correlate with phase development and microstructure

Phase analysis and microstructure evolution of a bone china body modified with scrap addition

Properties of a commercial bone china body containing varying amount of fired scrap of same material (0-12%) was studied and attempt was made to correlate the same with respect to phase analysis and microstructural evolution. Despite numerous studies on bone china by several authors, knowledge is still insufficient about the chemical reactions taking place among the various raw materials leading to very narrow firing range. In commercial production of bone china wares, loss during biscuit firing is significantly high. In this study attempt has been made to utilize a portion of the fired scrap in a commercial bone china composition and the effect of the same on the formation of the constituent phases has been tried to correlate with the properties developed. Phase analysis of the matured specimens revealed that there was gradual decrease in beta-Tri calcium phosphate (beta-TCP) content while increase in glassy phase was observed with progressive incorporation of scrap. Scrap incorporated body resulted in early maturity of the specimens as well as development of a very dense microstructure. Presence of scrap did not alter the anorthite phase content. The microstructure consisted of distinct regions of agglomerated spheroidal beta-TCP and lath shaped anorthite crystallites in a heterogeneous calcium aluminosilicate glassy matrix. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Studies on the dehydration kinetics and rehydration of YAG precursor powder in the hydroxyhydrogel form

YAG precursor powder was prepared in the hydroxyhydrogel form. Dehydration kinetic study and rehydration experiment was carried out to know the behavior of water molecules and hydroxide bonds present in the hydroxyhydrogel network structure with temperature. Rate constants and activation energies for dehydration and dehydroxylation were evaluated by static thermogravimetry. Percent rehydration was determined at different heat treatment temperatures. The results obtained were explained, correlated to establish the thermal stability of hydroxyhydrogel network structure and finally supported by the FTIR analysis. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Effect of pyrophyllite on the mullitization in triaxial porcelain system

China clay (kaolin) was progressively replaced by pyrophyllite in a conventional porcelain mix. Addition of 5% pyrophyllite as a replacement of china clay improved the fired strength by about 24% compared to that of the conventional body fired at 1300 degrees C. Percentage of mullite was found to increase in the fired specimens when kaolinite was progressively replaced by pyrophyllite. However, beyond 7.5% pyrophyllite addition, amorphous SiO(2) released from pyrophyllite dehydroxylate inhibited further recrystallization of mullite. There was very insignificant change in the phase compositions with mixes having pyrophyllite content higher than 7.5%. Entire phenomenon has been explained on the basis of structural reorganization of pyrophyllite during dehydroxylation. Presence of large amount of undissolved quartz of smaller size as well as isolated pores in the microstructures of specimens containing pyrophyllite more than 7.5% are assumed to hinder the propagation of crack and thereby improving the mechanical properties. The size and shape of mullite crystals is to a large extent controlled by the fluidity of the liquid matrix from which they grow and this is again a function of temperature and composition. (C) 2008 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Pyrophyllite as raw material for ceramic applications in the perspective of its pyro-chemical properties

General pyro-chemical properties of pyrophyllite were studied using one Indian variety as sample. In addition to normal routine analysis, thermal expansion, infrared spectroscopy, DTA, XRD and SEM studies were also employed to understand the pyro-chemical properties of the specimen at different temperatures. The results indicate that the specimen contains pyrophyllite as major phase with sericite, quartz and diaspore as minor phases. Unlike kaolinite, pyrophyllite contains low alumina and high silica which on heating mainly produces mullite and amorphous silica. Mullite crystallization from pyrophyllite is rather easy than that from kaolinite. The silica in turn yields large amount of viscous liquid at high temperature. It is suggested that pyrophyllite may be utilized in such compositions favourably where mullite is a desirable phase by partial replacement of china clay which is a viable alternative particularly in the background of depleting reserves of kaolinite and its continuous cost escalation. Additionally amorphous silica produced in the reaction system may acts as an in situ produced filler material that reduces the use of quartz in such system. (C) 2009 Published by Elsevier Ltd and Techna Group S.r.l

Effect of pyrophyllite incorporation in porcelain composition on mechanical properties and microstructure

China clay (Kaolin) and quartz in the ratio of 1:2 was progressively replaced by pyrophyllite in a conventional porcelain mix. Addition of 15% pyrophyllite as a replacement of a combination of china clay and quartz decreased the linear shrinkage by 5.03% while fired strength was improved by about 31.5% compared to that of the conventional body fired at 1300 degrees C. Incorporation of pyrophyllite beyond 15% resulted in early vitrification of porcelain composition, although in lower proportion the effect is not so significant. Percentage of mullite was found to increase in the fired specimens even when kaolinite was progressively replaced by pyrophyllite. However, beyond 22.5% pyrophyllite addition, there occurred large volume of glass formation. Presence of large volume of glassy phase as well as formation of large pores of various shapes resulted in deterioration in ceramic properties. The size and shape of mullite crystals is to a large extent controlled by the fluidity of the liquid matrix from which they grow and this is again a function of temperature and composition. (C) 2009 Published by Elsevier Ltd and Techna Group S.r.l

Simultaneous intercalation of two quaternary phosphonium salts into montmorillonite

Intercalation of montmorillonites with a mixture of intercalates has not been studied extensively. The objective of the present investigation was to study the effects of phosphonium-based intercalate mixtures on the properties (organic loading and basal spacing) of montmorillonite. These phosphonium-intercalated montmorillonites are promising candidates as high-temperature stable nanofillers for application in clay polymer nanocomposites. Two salts with different cationic heads and chain lengths were mixed in varying molar ratios and the mixtures were intercalated into the interlayer space of montinorillonite. Two sets were chosen based on the chain length and the cationic head-group structure of the two intercalated salts (referred to hereafter as set 1 and set 2). The resultant intercalated montmorillonite was characterized by thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. The organic loading of the intercalated montmorillonite increased with the proportion of longer carbon-chain intercalate in the mixture. The intensity of the characteristic XRD peak of each intercalate varied with the mole fraction percent of that intercalate in the solution mixture. No marked synergistic effect of the intercalate mixture on the basal spacing and organic loading properties of the intercalated montmorillonite was observed the proportional influence of individual components was found to be more prominent

Consideration of Alternate Raw Materials for Porcelain Tile Manufacture: The Effect of the Incorporation of Fired Scrap and Pyrophyllite

To address the problem of depleting reserves of raw materials for the manufacture of porcelain tiles a comparative analysis is made between two possible alternatives. The recycling of waste generated during tile manufacturing and the use of pyrophyllite in the composition were compared in relation to process parameters such as firing temperature and manifested properties such as linear shrinkage, porosity, bulk density and the sequence of sintering in a dilatometric study. It was found that the use of pyrophyllite in such systems is a better proposition. The conclusion was supported by microstructural and XRD phase analysis. The better ceramic properties in the pyrophyllite containing system are attributed to higher mullite formation at comparative firing temperature and a possible explanation for the same has been put forward. The use of pyrophyllite will open up an opportunity to utilize this non-conventional material in the commercial production of different porcelain products