Isolation and characterization of cellulose nanowhiskers from Acacia caesia plant

Acacia caesia (L.) Willd (soap bark) fiber is an abundant natural resource, that is rich in cellulose. The study reports the effective utilization of underutilized Acacia caesia fiber for the isolation of nanocellulose whiskers. The nanocellulose whiskers were isolated successfully from Acacia caesia fibers by following alkali, bleaching, and sulfuric acid treatment. The obtained nanocellulose whiskers were carefully investigated for its chemical composition, structure, morphology, crystallinity, and thermal stability. The chemical composition and Fourier transform infrared spectra of nanocellulose whiskers showed the elimination of the non-cellulosic parts present in the raw Acacia caesia fibers. The X-ray diffraction analysis showed an upsurge in the crystallinity of the cellulose fibers after the chemical treatments. The isolation of nanocellulose whiskers from Acacia caesia raw fiber was confirmed by electron microscopy analysis. The thermogravimetric analysis showed remarkably high char residue for the nanocellulose whiskers compared to raw fibers. Based on the properties of nanocellulose whiskers, it can be concluded that the nanocellulose whiskers produced from Acacia caesia raw fibers are potential reinforcing material for developing high-performance green composites.     

Effect of silane treated fly ash on physico-mechanical,morphological, and thermal properties of recycled poly(vinyl chloride) composites

The silane treatment on properties of fly ash (FA) and development of its composite using recycled poly(vinyl chloride) (r-PVC) material retrieve from waste wires and cable insulation are investigated in this work. The use of (3-aminopropyl)triethoxysilane was employed as a coupling agent with some other essential additives. The composites sheet was prepared by means of the melt mixing process and go along with the compression molding process. The superior properties on compatibility between silane-modified FA (FA(Si)) and r-PVC were successfully studied using rheological, thermomechanical, morphological, and water absorption analysis. Primary analysis of r-PVC and FA was employed using Fourier transform infrared spectroscopy analysis. The thermal stability of composites was stable up to 187°C. In addition, significant enhancement on tensile strength as well as young's modulus of composite as compared to untreated r-PVC/FA composites. Morphological properties of silane treated FA based composites presented the good distribution and excellent uniformity with higher wettability of FA particles within r-PVC matrix. The water absorption test showed decrease in water absorption with increase silane treatment concentration FA in the r-PVC matrix. It was remarkable to note that silane treated FA can be prepared as a composite using r-PVC matrix with further modified properties.     

Further Characterization of Intrastriatal Lipopolysaccharide Model of Parkinson’s Disease in C57BL/6 Mice

Parkinson’s disease (PD) is the most common movement disorder, characterized by progressive degeneration of the nigrostriatal pathway, which consists of dopaminergic cell bodies in substantia nigra and their neuronal projections to the striatum. Moreover, PD is associated with an array of non-motor symptoms such as olfactory dysfunction, gastrointestinal dysfunction, impaired regulation of the sleep-wake cycle, anxiety, depression, and cognitive impairment. Inflammation and concomitant oxidative stress are crucial in the pathogenesis of PD. Thus, this study aimed to model PD via intrastriatal injection of the inflammagen lipopolysaccharide (LPS)to investigate if the lesion causes olfactory and motor impairments, inflammation, oxidative stress, and alteration in synaptic proteins in the olfactory bulb, striatum, and colon. Ten µg of LPS was injected unilaterally into the striatum of 27 male C57BL/6 mice, and behavioural assessment was conducted at 4 and 8 weeks post-treatment, followed by tissue collection. Intrastriatal LPS induced motor impairment in C57BL/6 mice at 8 weeks post-treatment evidenced by reduced latency time in the rotarod test. LPS also induced inflammation in the striatum characterized by increased expression of microglial marker Iba-1 and astrocytic marker GFAP, with degeneration of dopaminergic neuronal fibres (reduced tyrosine hydroxylase immunoreactivity), and reduction of synaptic proteins and DJ-1 protein. Additionally, intrastriatal LPS induced inflammation, oxidative stress and alterations in synaptic proteins within the olfactory bulb, although this did not induce a significant impairment in olfactory function. Intrastriatal LPS induced mild inflammatory changes in the distal colon, accompanied by increased protein expression of 3-nitrotyrosine-modified proteins. This model recapitulated the major features of PD such as motor impairment and degeneration of dopaminergic neuronal fibres in the striatum, as well as some pathological changes in the olfactory bulb and colon; thus, this model could be suitable for understanding clinical PD and testing neuroprotective strategies.     

Measurement and Stochastic Computational Modeling of the Elastic Properties of Parallel Strand Lumber

This paper describes a model for the spatial variation of the elastic modulus of parallel strand lumber (PSL) that is based on bending experiments and also describes a validated stochastic computational model that incorporates orthotropic elasticity and uncertainty in strand geometry and material properties. The PSL exhibits significant variability both within members and between members, but this variability is less than that of equivalent sawn-wood members, and decreases with increasing member size. The correlation length of the elastic modulus is found to be several meters and is independent of the cross-sectional size. The variance of PSL elastic modulus is found to scale inversely with the number of strands in the cross section. The validated computational model is flexible enough to allow preliminary exploration of the properties of new mixes of species and strand sizes in PSL material design.     

Selection of a pull production control policy under different demand situations for a manufacturing system by AHP-algorithm

A multistage serial production system is considered in the present paper. A generalized model has been developed with the use of probabilistic demand situations for the end product. The demand situations considered are binomial, exponential, lognormal and Poisson. These demand patterns are used as input parameter for various production control policies. The output values for performance parameters are obtained by simulation. The production policies analyzed are Kanban, CONWIP and Hybrid as alternatives for controlling the engineering manufacture. In the presence of several performance measures, it often becomes difficult for the management to select the most appropriate policy. Analytic hierarchy process (AHP) has been implemented for the purpose of selection. Computational results have been reported along with the sensitivity analysis after designing and conducting various experiments.     

Design and manufacturing advisor for turbine disks

The design and manufacturing advisor (DMA) is a generic architecture for an expert system which assists in the process of product design. It integrates various parts of the production environment which affect the final product—such as fabrication, assembly, inspection and inventory. The design process can be partitioned into four stages: problem specification, feature specification, testing and generation. DMA facilitates the development of tractable designs, defined by the intersection of three spaces relating to specifications, features and productibility. The system consists of a domain-independent module and a domain-dependent module, each of which contains subcomponents; this modular structure facilitats system modification, expansion, and portability. The DMA has been validated by specializing the architecture to the design of gas-turbine disks for jet engines.     

Excitation of spontaneous vibrations in enclosed diffusion flames

The presence of Tollmien-Schlichting waves during the initial stages of the isothermal mixing of two axi-symmetical laminar streams of air has been confirmed by comparing data from hot wire measurements with published two-dimensional theoretical and experimental results for the stability of mixing and for transition in a boundary layer. Hot wire measurements in the flow field of steady or vibrating axi-symmetrical laminar diffusion flames are remarkably similar to those obtained during isothermal mixing. A travelling wave in the mean flow direction has also been established. Data for these flames agree with the results of a higher order stability analysis for natural convection flow past a vertical heated plate. It has been concluded that Tollmien-Schlichting waves are responsible for exciting flame vibrations.     

Scanning electron microscopy studies of abraded rubber surfaces

The surfaces of polybutadiene rubber (BR) and styrene-butadiene rubber (SBR) subjected to different degrees of abrasion have been studied by scanning electron microscopy (SEM). In the case of SBR it has been shown that abrasion begins with marks in the direction of rotation which are followed by fine ribbing and then by the formation of coarse, angular and prominent ridges. Prolonged abrasion produces folding and cavities on the surface. This change in abrasion mechanism has been explained as a result of heat build-up and high crack growth rate in SBR which occur beyond a certain stage. These help in softening the matrix and removing the surface. On the other hand, fractured surfaces of BR show that ridges begin to form at about 250 revolutions and there is no characteristic difference between the abraded surfaces at lower or higher degrees of abrasion.     

Electrochemical characterization of binderless, recompressed exfoliated graphite electrodes: electron-transfer kinetics and diffusion characteristics

Exfoliated graphite (EG) is prepared by the thermal exfoliation of graphite intercalation compounds at different temperatures. Surface and bulk physicochemical properties of EG are followed by spectroscopic and analytical methods and are observed to be a function of exfoliation temperature. EG particles can be recompressed without any binder and used as surface-renewable electrodes. Surface preparation is accomplished by either polishing or roughening the electrode surface using emery sheets. Effects of exfoliation temperature and the surface preparation on the electron-transfer kinetics and on the diffusion characteristics have been followed by electrochemical methods using several benchmark redox systems. It is found that the electron-transfer kinetics and the diffusion of K(4)[Fe(CN)(6)] are affected by the nature of the EG surface while that of iron(II)(1,10-phenanthroline)(3) and cobalt(II)(1,10-phenanthroline)(3) are not affected by the surface preparation. The redox systems are classified into different groups according to their kinetic sensitivity. Diffusion of electroactive species toward the EG electrodes is found to nonlinear. Current-time plots suggest that the recompressed EG electrodes can be modeled as fractals.     

A transaction model and multiversion concurrency control for mobile database systems

Transaction management on Mobile Database Systems (MDS) has to cope with a number of constraints such as limited bandwidth, low processing power, unreliable communication, and mobility etc. As a result of these constraints, traditional concurrency control mechanisms are unable to manage transactional activities to maintain availability. Innovative transaction execution schemes and concurrency control mechanisms are therefore required to exploit the full potential of MDS. In this paper, we report our investigation on a multi-versions transaction processing approach and a deadlock-free concurrency control mechanism based on multiversion two-phase locking scheme integrated with a timestamp approach. We study the behavior of the proposed model with a simulation study in a MDS environment. We have compared our schemes using a reference model to argue that such a performance comparison helps to show the superiority of our model over others. Experimental results demonstrate that our model provide significantly higher throughput by improving degree of concurrency, by reducing transaction wait time, and by minimizing restarts and aborts.