Compression Test and Plastic Strain of alpha-Al2O3 Single Crystals

Compression tests of single crystals are analyzed with respect to shear due to the friction at the loaded ends. This simple approach permits an explanation of the features associated with prism plane slip in sapphire (α-Al₂O₃), i.e., the shape changes of the specimens and the curvature of the glide planes.     

Use of Hydroxyl Functionalized (Meth)acrylic Cross‐Linked Polymer Microparticles as Chain Transfer Agent in Cationic Photopolymerization of Cycloaliphatic Epoxy Monomer, 2

This study is related to the use of hydroxyl functional acrylic cross‐linked polymer microparticles (CPM, also named microgels) as a chain transfer agent in cationic photopolymerization of cycloaliphatic epoxy monomer. All CPM were based on butyl acrylate and were consequently rubbery at ambient temperature. The effect of the stabilizing acrylate monomer used during the CPM synthesis was evaluated with respect to the viscoelastic properties of the photopolymerized cationic‐type epoxy films. The viscoelastic properties were correlated to the photopolymerized film morphology observed by transmission electron microscopy. Two acrylate monomers used as stabilizing agents during CPM synthesis were compared: cardura acrylate (CA) and lauryl acrylate (LA). CA was a good stabilizer for CPM in epoxy monomer before photocure and the CPM were well dispersed into the network after reaction. In contrast, LA was a poor stabilizer resulting in large CPM aggregation. The blend of these two types of CPM led to intermediate morphology, probably because of the flocculation of the CPM stabilized with LA. Conversely, CPM synthesized with a blend of the two stabilizing acrylate monomers induced in epoxy matrix a specific bi‐continuous morphology and consequently unique viscoelastic properties.

TEM micrographs of a photopolymerized film with 15 wt.‐% CPM(BA + 20%HEA)‐20%CA + 15% CPM(BA + 18%HEA)‐27%LA used as chain transfer agents.     

Properties of mLLDPE/LDPE blends in film blowing

We evaluated the inline birefringence of two blend systems in film blowing. The first system consisted of a metallocene catalyzed linear low density polyethylene (mLLDPE‐1) and a low density polyethylene (LDPE‐1); the second one was made of a metallocene catalyzed polyethylene containing sparse long chain branches (mLLDPE‐2) and another low density polyethylene (LDPE‐2). Experimental data show that before the crystallization starts, the birefringence of the mLLDPE‐2/LDPE‐2 blends is a linear function of blend composition, suggesting miscibility of the mLLDPE‐2/LDPE‐2 blends. However, the birefringence of the mLLDPE‐1/LDPE‐1 blends shows positive deviations with respect to a linear function of blend composition. This is caused by the existence of form birefringence, suggesting immiscibility of the mLLDPE‐1/LDPE‐1 blends. The nonuniform biaxial elongational viscosity (NUBEV) at the reference temperature of 175°C for LDPE‐1 was evaluated for different operating conditions. The results show that NUBEV is approximately a unique function of the deformation rate, confirming the validity of the assumptions and technique used for the NUBEV calculation. The NUBEV and the nonuniform biaxial Trouton ratio (NUTR) of the mLLDPE‐2/LDPE‐2 blends was also evaluated using the same technique. The NUBEV of all mLLDPE‐2/LDPE‐2 blends shows a strain‐thinning behavior within the deformation rates investigated. Furthermore, the NUTR results show that LDPE‐2 deviates largely from the Newtonian fluid behavior, whereas mLLDPE‐2 is quite close to the Newtonian behavior. Nevertheless, the NUTR of the mLLDPE‐2/LDPE‐2 blends is almost a linear function of blend composition. POLYM. ENG. Sci., 45:343–353, 2005. © 2005 Society of Plastics Engineers     

Coordination and Organometallic Polymers and Oligomers of Upper-Rim Functionalized Calix[4]arenes by Transition Metals

This short review focuses on recent advances in the syntheses, characterization and structures of coordination and organometallic complexes of upper-rim functionalized calix[4]arenes that form either small oligomers or polymers. This field is very limited, presumably due to the lack of X-ray data or reliable characterization that demonstrates the presence of oligomers or polymers. Nonetheless, the few published works already clearly demonstrate the immense versatility of the calix[4]arene macrocycle as it forms polymeric materials via coordination bondings with transition metals.     

Mechanical properties of autoclaved shell-aggregate

Waste solid propylene oxide sludge (POS) and fly ash were used as main raw material to prepare propylene oxide sludge aggregate (POSA) under the condition of autoclaved (180 ℃,1.0 MPa) curing. Three different test methods namely cylinder compressive strength (CCS), individual aggregate compressive strength (IACS) and strength contribution rate (SCR) proposed were used to characterize the mechanical properties of the autoclaved POSA. POS shell-aggregate with SCR of 94% were prepared under the hydrothermal synthesis and autoclaved curing. The experimental results indicate that CCS and IACS have good consistency in characterizing mechanical properties of POSA. It is suggested that SCR not only can characterize the strength of POSA core, but also can reflect the effect of shell on the performance of POSA. By means of least square method, relationships between CCS and IACS, CCS and SCR, IACS and SCR were deduced.     

Selective oxidation of secondary amines over titanium silicalite molecular sieves,TS-1 and TS-2

Titanium silicalite molecular sieves, TS-1 and TS-2 having MFI and MEL structures, respectively, catalyze the oxidation of secondary amines to the corresponding hydroxylamines using hydrogen peroxide as the oxidant. Higher concentrations of H₂O₂ lead to further oxidation of hydroxylamine to nitrone. Diffuse reflectance spectroscopy shows the formation of a titanium peroxo complex upon addition of hydrogen peroxide to the TS-1 catalyst. The titanium peroxo complex oxidizes the substrate and reforms to a titanyl group.     

Substrate specificity of the lipase fromCandida parapsilosis

Substrate specificity of the acyltransferase activity of the lipase (EC 3.1.1.3) fromCandida parapsilosis CBS 604 was studied in aqueous media. The specificity toward both acid and alcohol parts of a large number of acylglycerols and aliphatic esters was investigated. This lipase showed a high activity in the presence of esters with long-chain fatty acids and particularly unsaturated fatty acids with acis-Δ9 double bond. It was observed that the activity profile depended not only on the alcohol part of the acyl ester, but also on the temperature of the reactant medium. The best lipid substrates had their melting point between −40 to +20°C, 14 to 18 carbon atoms in the acyl group and 1 to 4 carbon atoms in the alkyl group. The enzyme, defined as an acyltransferase in a previous paper, showed a high affinity for primary and secondary alcohols with a short carbon chain (1 to 5 carbon atoms) as acyl acceptors. The influence of free alcohols in the reactant medium on the hydrolysis and alcoholysis activities of the enzyme is discussed. Two phenomena seem to be involved, depending on the alcohol: competition with water for the acyltransfer reaction and lipid substrate dilution when the alcohol places at the oil/water interface.     

Décantation assistée par ultrasons des eaux résiduaires

The impact of ultrasound on settling in water treatment has been studied. The effects already measured of ultrasound on the settling properties of various effluents have been identified and these effects have been observed in a static and a dynamic study. Sonification conditions suitable for optimizing such a process have been determined. The results show the primary role that stationary wave systems have in the settling of effluents (flocculated or not, synthesized or real). With flocculated effluents, a true impact on settling can be observed.     

Smart places: Multi-agent based smart mobile virtual community management system

Now-a-days advances in mobile device technology aim to build complex computational systems providing a maximum level of flexibility, decentralization, simplest form of interactivity, and ease of use. Recently, the launch of the agent-oriented platform JaCaMo and its Android client based platform JaCa-Android have provided an appropriate level of abstraction to build smart mobile client server systems providing these attributes. By using these platforms, we have developed a multi-agent based Smart Mobile Virtual Community Management System (SMVCMS) that makes it possible to provide a decentralized and open management of virtual communities. This paper addresses the design and architecture of our multi-agent server and client application. It elaborates different features of our system; such as how a participant in virtual communities is supported by a Jason agent that encapsulates the logic and the control of the participation in a virtual community (such as publishing posts, notifying members, making recommendations for the user, etc.). It also discusses how the set of CArtAgOartifacts provides the basic functionalities and operations giving access to the functionalities for knowledge exchange in virtual communities, and personal agents onAndroid exploit these artifacts to execute their tasks while achieving their individual and collective goals. We have employed SMVCMS in the context of Smart Cities and found that the system fulfills the desired goals, such as decentralization of community management, personalized automatic management and discovery of communities, autonomy of agents and flexibility so that any agent can create its own community with the maximum level of ease.     

Copolymerization of butyl acrylate with styrene in presence on ZnCl2

Summary Copolymers of butyl acrylate-styrene were prepared in presence of ZnCl₂. The formation of a complex was determined by infrared spectroscopy. The copolymers were characterized by IR, NMR and by solubility. The study of their structure as a function of the initial monomer composition and the analysis of UV spectra showing varying intensity of the carbonyl peaks confirmed the presence of an alternating copolymer. The reactivity ratios of the two monomers were determined and found to be 0.1 for both butyl acrylate and styrene.