Apatite wollastonite–poly methyl methacrylate bio-composites

Bio-composites consisting of sol–gel processed apatite wollastonite (AW) glass ceramics and poly methyl methacrylate (PMMA) were prepared by hot compaction method. Density of the composites decreased with increase in PMMA content, while, biaxial flexural strength (BFS) was 21 MPa for 20 wt.% PMMA and beyond which it decreased. A correlation between phase compositions of AW glass ceramics with BFS was attempted from the XRD results. In vitro bioactivity of the composites in a simulated body fluid (SBF) showed the formation of spherical globules on the surface within 7 days of soaking as observed by environmental SEM. Thin film XRD and EDX measurement confirmed these globules to be bone like apatite with Ca/P ratio 1.53 and FTIR measurement showed the corresponding peaks for phosphates. Results indicated the bone bonding ability of the composites by forming a surface apatite (calcium phosphate) layer in SBF and the growth increased with increase in soaking durations. ICP measurement of the remaining SBF after 7, 14 and 21 days soaking of samples was found to be in good agreement with the EDX analysis results.     

Prediction of heat transfer coefficient during condensation of water and R-134a on single horizontal integral-fin tubes

This paper presents a few salient features of an investigation carried out to study the heat transfer augmentation during condensation of water and R-134a vapor on horizontal integral-fin tubes. The experimental investigation was performed on two different experimental set-ups for water and R-134a. The test-sections were manufactured by machining fins over plain copper tubes of 24.4 ± 0.6 mm outside diameter. The performance of two types of finned tubes viz. circular integral-fin tubes (CIFTs) and spine integral-fin tubes (SIFTs) was studied for the condensation of water and R-134a. These tubes were positioned one by one inside the test-condenser to perform the experiments. All together the experiments were conducted for the condensation on 10 different test-section tubes. With the help of the experimental results, authors have developed an empirical equation. This equation predicts the condensing heat transfer coefficient from their own experimental data for the condensation over CIFTs and SIFTs within a range of ± 15% and experimental data of other thirteen investigators in a range of ± 35% for condensation of water and different refrigerants.     

Modeling no-notice mass evacuation using a dynamic traffic flow optimization model

This paper presents a network transformation and demand specification approach for no-notice evacuation modeling. The research is aimed at formulating the Joint Evacuation Destination-Route-Flow-Departure (JEDRFD) problem of a no-notice mass evacuation into a system optimal dynamic traffic assignment model. The proposed network transformation technique permits the conversion of a typical transportation planning network to an evacuation network configuration in which a hot zone, evacuation destinations, virtual super-safe node and connectors are established. Combined with a demand specification method, the JEDRFD problem is formulated as a single-destination cell-transmission-model-based linear programming model. The advantage of the proposed model compared with prior studies in the literature is that the multi-dimensional evacuation operation decisions are jointly obtained at the optimum of the JEDRFD model. The linear single-destination structure of the proposed model implies another advantage in computational efficiency. A numerical example is given to illustrate the modeling procedure and solution properties. Real-time operational issues and data requirements are also discussed.     

Poly(ethylene oxide)/clay nanocomposites for solid polymer electrolyte applications

Poly(ethylene oxide) (PEO)/clay nanocomposites were prepared using a solution intercalation method. The organoclay (Nanocore I30E) used for nanocomposite synthesis was basically an octadecylammonium salt of montmorillonite clay prepared using an ion exchange method. Nanocomposite‐based solid polymer electrolytes were prepared using LiBF₄. The nanocomposite structures were characterised using wide‐angle X‐ray diffraction. The crystallisation behaviour and thermal properties were studied using differential scanning calorimetry. It was found that the crystallinity of the composite electrolytes decreases with increasing clay concentration up to 7.5 wt% and then increases with a further increase in clay concentration. The trend is different from that observed in PEO/clay nanocomposites without lithium salt where the crystallinity gradually decreases with increasing clay concentration. The solid polymer electrolyte samples were evaluated using an alternating current impedance analyser. A considerable increase in room temperature conductivity was observed at the optimum clay concentration. The conductivity decreases beyond the optimum clay concentration. Copyright © 2007 Society of Chemical Industry     

Comparative thermal performance evaluation of an active solar distillation system

In this paper, thermal models of all types of solar collector‐integrated active solar stills are developed based on basic energy balance equations in terms of inner and outer glass temperatures. In this paper, hourly yield, hourly exergy efficiency, and hourly overall thermal efficiency of active solar stills are evaluated for 0.05 m water depth. All numerical computations had been performed for a typical day in the month of 07 December 2005 for the climatic conditions of New Delhi (28°35′N, 77°12′E, 216 m above MSL). The thermal model of flat‐plate collector integrated with active solar still was validated using the experimental test set‐up results. Total daily yield from active solar still integrated with evacuated tube collector with heat pipe is 4.24 kg m^?2 day^?1, maximum among all other types of active solar stills. Copyright © 2007 John Wiley & Sons, Ltd.     

Characterization of co-crystallized sucrose entrapped with cardamom oleoresin

Cardamom oleoresin emulsified with gum acacia was encapsulated by co-crystallization in a supersaturated sucrose solution to prepare flavoured sucrose cubes. The co-crystals with and without cardamom oleoresin were characterized at 25°C and 33%, 63% and 93% relative humidity for hygroscopicity and crystallinity vis-à-vis pure crystal sucrose. Co-crystallized sucrose cubes showed lower hygroscopicity at 93% relative humidity, a longer dissolution time, and a decreased crystallinity as compared to crystal sucrose. The active components of cardamom oleoresin such as 1,8-cineole (30.23%) and α-terpinyl acetate (46.42%) in cardamom oleoresin was quantified by gas chromatography. The encapsulation efficiency of 1,8-cineole and α-terpinyl acetate in lab-made co-crystallized sucrose cubes was approximately 35.23% and 67.18%, respectively. This approach could contribute to value addition of cardamom oleoresin for flavoured tea and also have potential applications in traditional Indian sweets.     

Stability of active components of cardamom oleoresin in co-crystallized sugar cube during storage

Cardamom oleoresin was co-crystallized to formulate flavoured sugar cubes for table top use in tea. The flavoured sugar cubes were packed in two-layer composite and three-layer metalized laminate packaging materials and evaluated for 5 months at relative humidities of 33%, 63% and 93% and temperatures of 5 °C, 25 °C and 45 °C, respectively. The major active components of cardamom oleoresin viz. 1,8-cineole and α-terpinyl acetate in the co-crystallized sugar cubes was quantified by gas chromatography throughout the storage period. The major active components of cardamom in the oleoresin, freshly prepared flavoured sugar cubes, and in sugar cubes stored under extreme condition of storage at 45 °C under all the relative humidities were identified by GCMS. The rate of degradation of 1,8-cineole was higher than α-terpinyl acetate as seen from the kinetic study and activation energy in both the packaging materials under all conditions of storage.     

A multi-agent-based framework for cloud service discovery and selection using ontology

As cloud computing is getting matured day by day, there has been overwhelming interest among the users to avail a plethora of cloud services. Often, these services appear identical in terms of their functionality though they differ in pricing models, computational power, storage policies and Quality-of-Service parameters making the process of service discovery and selection an intricate task. In the absence of any standard specifications, cloud service providers continue to use their own vocabulary and this further complicates the selection process. Even popular search engines like Google and MSN are not efficient enough to properly identify the most appropriate cloud service that can meet customer requirements. Thus, in the presence of multiple selection parameters and constraints, selecting a required cloud service is a daunting task. In order to address this issue, we work toward developing a reasoning mechanism to optimally resolve the similarities across cloud services by using cloud ontology. A multi-agent-based framework has been proposed for effective cloud service discovery and selection with the help of a standardized service registry and by employing semantically guided searching process.     

Effect of heat treatments on apatite-forming ability of NaOH- and HCl-treated titanium metal

Titanium (Ti) metal was soaked in HCl solution after NaOH treatment and then subjected to heat treatments at different temperatures. Their apatite-forming abilities in a simulated body fluid (SBF) were discussed in terms of their surface structures and properties. The nanometer scale roughness formed on Ti metal after NaOH treatment remained after the HCl treatment and a subsequent heat treatment below 700°C. Hydrogen titanate was formed on Ti metal from an HCl treatment after NaOH treatment, and this was converted into titanium oxide of anatase and rutile phases by a subsequent heat treatment above 500°C. The scratch resistance of the surface layer increased with the formation of the titanium oxide after a heat treatment up to 700°C, and then decreased with increasing temperature. The Ti metal with a titanium oxide layer formed on its surface showed a high apatite-forming ability in SBF when the heat treatment temperature was in the range 500–700°C. The high apatite-forming ability was attributed to the positive surface charge in an SBF. These positive surface charges were ascribed to the presence of chloride ions, which were adsorbed on the surfaces and dissociated in the SBF to give an acid environment.