Evaluation of improvement of physical and mechanical properties of bamboo fibers due to alkali treatment

Bamboo strips treated with caustic solutions of different concentrations, e.g., 5%, 10%, 15%, 20%, 25%, and 50%, were subjected to mechanical testing giving stresses on tensile strength, percent elongation at break, flexural strength, flexural modulus, and toughness. The change in average density was ?15%, and the weight loss value shows a maximum of 21.94% at 50% alkali treatment. The mechanical properties of bamboo strips increase steadily with increasing concentration of caustic soda, showing a comparable increased value at 15 and 20%, and then exhibiting a gradual fall. The percent elongation at break corroborates these observations showing a continuous decreasing trend. The properties under investigation exhibit a clear transition in between 15 and 20% alkali concentration. The morphology of strips was studied by scanning electron microscope and polarizing light microscope. The crystal structure of both untreated and treated strips was compared by XRD analysis. In both cases, the breakdown of the crystal structures of the cellulose fibers and the recrystallization or reorientation of the degraded chains that are devoid of hemicellulose are quite apparent. However, at a very high concentration (to the extent of 25%) the breakdown of structure predominates much more over the reorientation or recrystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A space-based microwave radar concept

A space-based microwave radar (SBR) concept is defined using a tether trans/receive antenna supported between two gravity gradient low Earth-orbiting satellites. A cluster of four tether antennas, each of 6 km maximum length and 1.5 km separation between tethers, constitutes a radar. A system of 8 to 11 such clusters constitutes the overall radar scheme, which will cover approximately one third of the Earth's surface for detecting sea-based targets. Issues identified are the array structure, the coherence of tethered arrays, grating lobe energy clamping, clutter effects, communications, system requirements, and the overall radar system concept, including stability considerations. The baseline definition of an alternate space-based radar scheme is presented. A significant amount of R&D efforts will be required to derive practical solutions of the proposed scheme     

The molecular mechanisms of actin-based intracellular motility by Listeria monocytogenes

A rapid, sensitive method was developed for the quantification of the R- and S-enantiomers of ketoprofen and their acyl glucuronide conjugates in the plasma and dialysate of hemodialysis-dependent anephric patients. Unconjugated R- and S-ketoprofen plasma concentrations were determined directly by liquid chromatography using a S,S-Whelk-O1 chiral stationary phase. R- and S-Ketoprofen glucuronide for use as standard were resolved using a C18 reversed-phase HPLC column with a mobile phase containing the ion-pair reagent tetrabutylammonium hydrogen sulfate. Plasma glucuronides, however, could not be directly quantified due to matrix interference. Therefore, the glucuronides were isolated using reversed-phase HPLC and quantified after alkaline hydrolysis using the S,S-Whelk-O1 chiral stationary phase column.     

An alternate method for using a visual discrimination model (VDM) to optimize soft-copy display image quality

Researchers have developed visual discrimination models (VDMs) that can predict a human observer's ability to detect a target object superposed on an image. These models incorporate sophisticated knowledge of the properties of the human visual system. In the predictive approach, termed conventional VDM usage, two input images with and without a target are analyzed by an algorithm that calculates a just-noticeable-difference (JND) index, which is a taken as a measure of the detectability of the target. A new method of using the VDM is described, termed channelized VDM, which involves finding the linear combination of the VDM-generated channels (which are not used in conventional VDM analysis) that has optimal classification ability between normal and abnormal images. The classification ability can be measured using receiver operating characteristic (ROC) or two alternative forced choice (2AFC) experiments, and in special cases they can also be predicted by signal detection theory (SDT) based model-observer methods. In this study simulated background and nodule containing regions were used to validate the new method. It was found that the channelized VDM predictions were in excellent qualitative agreement with human-observer validated SDT predictions. Either VDM method (conventional or channelized) has potential applicability to soft-copy display optimization. An advantage of any VDM-based approach is that complex effects, such as visual masking, are automatically accounted for, which effects are usually not included in SDT-based methods.     

Influence of Nano Silica on Mechanical and Durability Characteristic of Mortar made by Partial Replacement of Natural Fine Aggregate with Recycled Fine Aggregate

Silicon - To implement sustainability concepts in the construction industry, the possibility of utilizing the recycled fine aggregate obtained from the crushing of coarse aggregate debris of...     

Alkylation of naphthalene with alcohols over mesoporous MCM-41

Mesoporous MCM-41 is found to promote alkylation of naphthalene by alcohols. In addition to the preferred branched side chain productsn-alkylated product is also observed in the case of propylation of naphthalene.     

Lightweight graphics instrumentation for game state-specific power management in Android

Battery life is a major concern on portable devices like smartphones and tablet PCs. On these devices, games constitute the class of most popular applications and are at the same time highly compute-intensive. Every game consists of several states like the loading, main menu and the gaming state. Each of those states has its own workload characteristics, e.g., the loading phase is likely to be memory bound and the main menu state is less interactive than the gaming state. We propose an interception technique that allows to profile the game and detect its current state based on the game’s communication with the underlying OS. Current power management governors are unaware of the running applications and scale the processor’s voltage and frequency merely based on the system’s utilization. We provide the game’s state information and workload profile to our governor which selects the processing frequency such that the desired frame rate of the current state is ensured. This leads to an optimal choice of processing frequencies and thereby significantly reduces power consumption. We have implemented the scheme on an Android-based Samsung Galaxy Nexus smartphone using popular games like Jetpack Joyride and Temple Run. We reduced the CPU’s power consumption by up to 43.2 % compared to the Android interactive governor without impacting the gaming experience. Motivated by these results we propose a power management API that would allow game developers to significantly reduce the power consumption of their game using simple API calls.     

Poly(ethylene oxide)/clay nanocomposite: Thermomechanical properties and morphology

Poly(ethylene oxide) (PEO)/clay nanocomposites were prepared by a solution intercalation method using chloroform as a solvent. The nanocomposites were characterised by X-ray diffraction (XRD), differential scanning calorimetry (DSC), hot-stage polarized optical microscopy (POM), Fourier transform infrared spectroscopy (FT-IR), tensile analysis, dynamic mechanical analysis (DMA) characterisation techniques. Formation of nanocomposite was confirmed by X-ray diffraction (XRD) analysis. A decrease in PEO crystallinity in case of nanocomposite, was confirmed by a decrease in the heat of melting and spherulite size as indicated by DSC and POM studies, respectively. Improvement in tensile properties in all respect was observed for nanocomposites with optimum clay content (12.5 wt%). DMA studies indicate an increase in loss peak temperature and broadening of loss peak as a result of clay intercalation.     

Studies on engineering properties of PVC–PMMA semi‐interpenetrating polymer networks

Semi1 and semi2 interpenetrating polymer networks (IPNs) of PVC and in situ formed PMMA have been synthesized using diallyl phthalate and ethylene glycol dimethacrylate as the crosslinkers of PVC and PMMA, respectively. These two types of IPNs have been compared w.r.t their physical, mechanical, and thermal properties and an endeavor has been made to find a correlation of these properties with the morphology generated in these systems. The semi1 IPNs displayed a decrease in their mechanical parameters and the physical properties as well, while in contrast, the semi2 IPNs exhibited a marginal increase in the corresponding values after an initial drop upto about 15% of crosslinked PMMA incorporation when compared to the crosslinked PVC in the case of semi1 IPN and linear PVC in the case of semi2 IPN. The various samples of semi1 and semi2 IPNs showed a two‐stage degradation typical of PVC, while confirming the increased stability with the samples having higher percentages of PMMA. The influence of crosslinking of the major matrix in semi1 IPN was almost counterbalanced by the influence of crosslinking in the dispersed PMMA phase in the case of semi2 IPN. The softening characteristics as detected by the extent of penetration of the probe, as has been detected by thermomechanical analysis, are in conformity with their mechanicals. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1725–1735, 2005