Effect of copper chromite and copper chromitecopper oxide mixture catalysts on the thermal decomposition of ammonium perchlorate and composite solid propellant

Thermal decomposition of powdered ammonium perchlorate (AP), polystyrene (PS) and $\text{AP}\text{PS}$ propellant, catalysed by freshly-prepared CuCr₂O₄ and mixtures of CuCr₂O₄ and CuO, has been studied with a low concentration (1% by mass) of the catalysts. It appears that decomposition is increased due to heterogeneous catalysis. The kinetics of thermal decomposition of AP in the presence of CuCr₂O₄ in the orthorhombic region of AP have also been studied.     

Chemical Constituents, Antimicrobial Investigations, and Antioxidative Potentials of Anethum graveolens L. Essential Oil and Acetone Extract: Part 52

ABSTRACT: The antioxidant, antifungal, and antibacterial potentials of essential oil and acetone extract of Anethum graveolens L. were investigated in the present study. The extract has shown excellent activity for the inhibition of primary and secondary oxidation products for rapeseed oil in comparision with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), which were evaluated using peroxide, thiobarbituric acid, p‐anisidine, and carbonyl values. The activity of extract was further confirmed using other antioxidant properties such as ferric thiocyanate method inlinoleic acid system, which reducing power and scavenging effect (%) on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical. Using inverted Petri plate method, the volatile oil completely inhibited the growth of Fusarium graminearum at 6 μL dose. Moreover, using poison food technique, the essential oil was found to be highly effective for controlling the growth of Penicillium citrinum and Aspergillus niger. In antibacterial investigations, using agar well diffusion method, the extract has shown better activity for Staphylococcus aureus and Bacillus cereus in comparison with commercial bactericide. However, essential oil has shown better activity for Pseudomonas aeruginosa. Gas chromatographic‐mass spectroscopy studies on essential oil resulted in the identification of 35 components, which account for the 98.9% of the total amount. The major component was carvone (55.2%) followed bylimonene (16.6%), dillapiole (14.4%), andlinalool (3.7%). The analysis of acetone extract showed the presence of 25 components, which account for 94.5% of the total amount. The major components were dill apiole (43.2%), linoleic acid (23.1%), trans‐anethole (11.0%), 2‐propanone, 1‐(4‐methoxyphenyl) (4.6%), carvone (3.1%), p‐anisaldehyde (2.7%), and myristicin (1.5%). In conclusion, the results presented here show that dill essential oil could be considered as a source for natural antimicrobial, whereas its extract could be considered as an alternative source of natural antioxidant.     

Defining specialized design similarity measures

Similar product designs resemble each other and have similar attributes and characteristics. When examining a product design to create its process plan, design its fixture, or estimate its manufacturing cost, manufacturing engineers often identify one or more similar products that the factory has manufactured in the past. They may do this from memory, from a file cabinet, or from a database (in a product data management system). Then, they retrieve the process plan (or fixture or cost estimate) for the similar product and modify it for the new product. Manufacturing and process planning experts use a complex set of rules, guidelines, and other knowledge to determine how similar two products are. Computer-aided process planning tools, however, generally use simpler, less sophisticated procedures for determining similarity. These traditional procedures may be inappropriate for specific settings. This paper presents an approach for developing function-specific design similarity measures. Such a measure explicitly exploits the specific need for similar products and thus improves variant approaches for process planning, fixture planning, and manufacturability evaluation. The approach is applied to a specific fixture planning domain.     

On the relative execution times of distributed protocols

We provide a formalism for comparing the average execution time of distributed protocols in a manner independent of the properties of the network on which the protocols are executed. The formalism takes into account computation time, the time to transfer information, the time spent by a site waiting to synchronize and the overlap among them. We define transformations on protocols which may change the synchronization structure, the information transferred or the amount of local computation. We show that if a sequence of such transformations can be applied to a protocol to obtain another protocol, then the final protocol runs at least as fast as the initial protocol. Different sets of tranformations give rise to different notions of comparison. We develop two such notions and explore their properties. We also give results which relate our notion of protocol transformation to transformational techniques for protocol design.This work was supported by NSF under Grant CCR87-01671 and CCR89-01966. This work was performed while the first author was at SUNY, Stony Brook.     

A highly asynchronous minimum spanning tree protocol

Summary In this paper, we present an efficient distributed protocol for constructing a minimum-weight spanning tree (MST). Gallager, Humblet and Spira [5] proposed a protocol for this problem with time and message complexitiesO(N logN) andO(E+NlogN) respectively. A protocol withO(N) time complexity was proposed by Awerbuch [1]. We show that the time complexity of the protocol in [5] can also be expressed asO((D+d) logN), whereD is the maximum degree of a node andd is a diameter of the MST and therefore this protocol performs better than the protocol in [1] wheneverD+d<N/logN. We give a protocol which requiresO(min(N, (D+d)logN)) time andO(E+NlogNlogN/loglogN) messages. The protocol constructs a minimum spanning tree by growing disjoint subtrees of the MST (which are referred to asfragments). Fragments having the same minimum-weight outgoing edge are combined until a single fragment which spans the entire network remains. The protocols in [5] and [1] enforce a balanced growth of fragments. We relax the requirement of balanced growth and obtain a highly asynchronous protocol. In this protocol, fast growing fragments combine more often and there-fore speed up the execution. Gurdip Singh received the B. Tech degree in Computer Science from Indian Institute of Technology, New Delhi in 1986 and the M.S. and Ph.D. degrees in Computer Science from State University of New York at Stony Brook in 1989 and 1991 respectively. Since 1991, he has been an Assistant Professor in the Department of Computing and Information Sciences at Kansas State University. His research interest include design and verification of distributed algorithms, communication networks and distributed shared memories. Arthur Bernstein received his PhD in Electrical Engineering from Columbia University. He is currently a professor in the Computer Science Department at the State University of New York at Stony Brook. His research interests center around concurrency in programming and data-base systems.This work was supported by NSF under grants CCR8701671, CCR8901966 and CCR9211621     

Studies on energetic compounds part 15 : Transition metal salts of NTO as potential energetic ballistic modifiers for composite solid propellants

Abstract

The combustion of hydroxyl terminated polybutadiene (HTPB) - ammonium perchlorate (AP) composite solid propellants has been studied using transition metal (Mn, Fe, Co, Ni, Cu and Zn) salts of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) as energetic burning rate additives. The steady burning rate (r) was considerably enhanced with Cu(NTO)₂ and Fe(NTO)₂ whereas moderately enhanced with Zn(NTO)₂ and Co(NTO)₂ at low concentration (2% by wt.). Activity of these salts has been observed during isothermal decomposition of AP at 260°C. The values of ignition delay (t_iJ), ignition temperature (T_ign.) and activation energy for ignition (E?) for AP has also been lowered when these salts are added to it at 2% wt. concentration. The processing parameters as well as mechanical properties of the propellants with Cu(NTO)₂ as additive have been studied in detail. The r of the propellants (both highly aluminized and less aluminized) with Cu(NTO)₂ as additive at various concentrations, has been determined at high pressures, also shows its activity during combustion, The condensed phase activity of Cu(NTO)₂ during propellant decomposition has also been studied using TG-DTG techniques.     

Hexammine metal perchlorates as energetic burning rate modifiers

Abstract

Four transition metal hexammine perchlorates namely, [Cu(NH₃)₆](ClO₄)₂, [Co(NH₃)₆](ClO₄)₂, [Ni(NH₃)₆](ClO₄)₂ and [Zn(NH₃)₆](ClO₄)₂ have been prepared, characterized and used as ballistic modifiers in the combustion of hydroxy terminated polybutadiene (HTPB)-Ammonium perchlorate (AP) composite solid propellants. Burning rate was considerably enhanced with [Co(NH₃)₆](ClO₄)₂ and [Cu(NH₃)₆](ClO₄)₂ whereas moderately with [Ni(NH₃)₆](ClO₄)₂ and [Zn(NH₃)₆](ClO₄)₂ at low concentration (2% by wt). [Co(NH₃)₆](ClO₄)₂ was found to accelerate the burning rate by three fold at two percent concentration and it can be exploited as potential energetic burning rate modifier for HTPB-AP propellants. Further, ignition delay studies showed that the deflagration of propellants and AP was accelerated by these additives.     

Radical Roles for RAGE in the Pathogenesis of Oxidative Stress in Cardiovascular Diseases and Beyond

Oxidative stress is a central mechanism by which the receptor for advanced glycation endproducts (RAGE) mediates its pathological effects. Multiple experimental inquiries in RAGE-expressing cultured cells have demonstrated that ligand-RAGE interaction mediates generation of reactive oxygen species (ROS) and consequent downstream signal transduction and regulation of gene expression. The primary mechanism by which RAGE generates oxidative stress is via activation of NADPH oxidase; amplification mechanisms in the mitochondria may further drive ROS production. Recent studies indicating that the cytoplasmic domain of RAGE binds to the formin mDia1 provide further support for the critical roles of this pathway in oxidative stress; mDia1 was required for activation of rac1 and NADPH oxidase in primary murine aortic smooth muscle cells treated with RAGE ligand S100B. In vivo, in multiple distinct disease models in animals, RAGE action generates oxidative stress and modulates cellular/tissue fate in range of disorders, such as in myocardial ischemia, atherosclerosis, and aneurysm formation. Blockade or genetic deletion of RAGE was shown to be protective in these settings. Indeed, beyond cardiovascular disease, evidence is accruing in human subjects linking levels of RAGE ligands and soluble RAGE to oxidative stress in disorders such as doxorubicin toxicity, acetaminophen toxicity, neurodegeneration, hyperlipidemia, diabetes, preeclampsia, rheumatoid arthritis and pulmonary fibrosis. Blockade of RAGE signal transduction may be a key strategy for the prevention of the deleterious consequences of oxidative stress, particularly in chronic disease.     

Thermolysis of AP–additive mixtures,III1

Abstract

Thermolysis of ammonium perchlorate (AP) in presence of additives such as CaCO₃ and CaO has been investigated by Ignition delay, DTA, and photomicrography techniques. The ignition delay, ignition temperature, and decomposition temperature and activation energy are found to decrease when CaO was incorporated in AP. However, CaCO₃ affected the ignition of AP at higher temperatures (622-770°K) but very little effect was observed at lower temperatures (<623°K). Thermolysis of AP seems to proceed through condensed phase reactions in presence of CaO and CaCO₃ and role of these additives in the deflagration and decomposition of AP has also been discussed.     

Antioxidant and antimicrobial activities of essential oil and various oleoresins of Elettaria cardamomum (seeds and pods)

BACKGROUND: This paper describes the chemical analysis of the essential oil and various oleoresins of Elettaria cardamomum (seeds and pods) by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) techniques. It also compares the effects of the different extraction solvents used (chloroform, methanol, ethanol and diethyl ether) on the antioxidant and antimicrobial activities of the essential oil and oleoresins. RESULTS: The essential oil was found to contain 71 compounds. The major components were α‐terpinyl acetate (44.3%), 1,8‐cineole (10.7%), α‐terpineol (9.8%) and linalool (8.6%). The chloroform and methanol oleoresins both contained α‐terpinyl acetate (21.8 and 25.9% respectively) as the main component, while 5‐hydroxymethylfurfural (28.9%) was the most abundant compound in the ethanol oleoresin. However, very few components (total 0.61%) were found in the diethyl ether oleoresin. The antioxidant activities of the essential oil and oleoresins, studied in mustard oil by monitoring the peroxide value of the oil substrate, were comparable to those of the synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) at 0.02% concentration. The essential oil exhibited strong antibacterial activity against the micro‐organisms Staphylococcus aureus, Bacillus cereus, Escherichia coli and Salmonella typhi at 3000 ppm by the agar well diffusion method. Antifungal activity was tested against the food‐borne fungi Aspergillus terreus, Penicillium purpurogenum, Fusarium graminearum and Penicillium madriti. The methanol and ethanol oleoresins gave the best results against A. terreus at 3000 ppm by the poison food method. CONCLUSION: This study provides important information about the chemistry and antioxidant and antimicrobial properties of E. cardamomum. Copyright © 2007 Society of Chemical Industry