Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the con- centration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immu- nologically tolerated "tissue" for wound hea ing and as a model for studying fibroblast function are discussed.

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative

Delamination formation, evaluation and suppression during drilling of composite laminates: A review

Carbon fibre reinforced polymer (CFRP) composites have excellent specific mechanical properties, these materials are therefore widely used in high-tech industries like the automobile and aerospace sectors. The mechanical machining of CFRP composites is often necessary to meet dimensional or assembly-related requirements; however, the machining of these materials is difficult. In an attempt to explore this issue, the main objective of the present paper is to review those advanced cutting tools and technologies that are used for drilling carbon fibre reinforced polymer composites. In this context, this paper gives a detailed review and discussion of the following: (i) the machinability of CFRP including chip removal mechanisms, cutting force, tool wear, surface roughness, delamination and the characteristics of uncut fibres; (ii) cutting tool requirements for CFRP machining; and (iii) recent industrial solutions: advanced edge geometries of cutting tools, coatings and technologies. In conclusion, it can be stated that advanced geometry cutting tools are often necessary in order to effectively and appropriately machine required quality features when working with CFRP composites.

Advanced cutting tools and technologies for drilling carbon fibre reinforced polymer (CFRP) composites: A review

Microalgal biodiesel has emerged as an environment friendly alternative to the existing fossil fuels. The commercial production of this biodiesel is still challenging due to several technical and economic issues, which span from mass cultivation of microalgae to the biodiesel production. Mass cultivation is the most critical step in terms of water and nutrient requirement. Industrial wastewater such as textile wastewater (TWW) is a cheap source for water, which additionally contains necessary nutrients (phosphate, nitrates, micronutrients etc.) and organic dyes (potential carbon source) for algae cultivation. The application of microalgae for biodiesel production employing single objective strategy is not sustainable. Microalgae can be effectively employed to bioremediate TWW (dyes and nutrients removal) and to produce biodiesel from grown microalgae. This process integration (bioremediation-biodiesel production) can potentially improve biodiesel production and wastewater treatment. However, this process coupling needs to be thoroughly investigated to identify and optimize critical process factors (algal species, cultivation and harvesting methods, bioremediation mechanism etc.). This study has reviewed the status of TWW as potential source of water and nutrients, role of different algal species in the bioremediation of TWW, different cultivation systems, harvesting and biodiesel production methods. This review also suggests future research and development challenges for coupled textile wastewater treatment and microalgal biodiesel production.

Bioremediation of textile wastewater and successive biodiesel production using microalgae

Recent advancement in the natural fiber polymer composites: A comprehensive review

High speed machining is now acknowledged to be one of the key manufacturing technologies to ensure high productivity and throughput. Drilling of CFRP, though a challenging task, is being performed successfully at low spindle speeds. However high speed drilling in CFRP thin laminates has not been explored much. This paper reports an experimental investigation of a full factorial design performed on thin CFRP laminates using K20 carbide drill by varying the drilling parameters such as spindle speed and feed rate to determine optimum cutting conditions. The hole quality parameters analyzed include hole diameter, circularity, peel-up delamination and push-out delamination. Analysis of variance (ANOVA) was carried out for hole quality parameters and their contribution rates were determined. Genetic Algorithm (GA) methodology was used in the multiple objective optimization (using MATLAB R2010a software) to find the optimum cutting conditions for defect free drilling. Tool life of the K20 carbide drill was predicted at optimized cutting speed and feed.

Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates

In recent days, automobile and construction industries are focus on the light weight, environmental friendly materials with good mechanical properties. Glass fiber reinforced composites have excellent specific properties and are widely used because of reduced mass. However the manufacturing of glass fibers and end of life disposal are the major problem to the environment. To overcome these problems, natural fibers are used to manufacture composites. Flax is the one of the naturally available fiber having good mechanical properties than other natural fibers. It needs to be pointed out that most of research effort about the flax fiber reinforced composites focuses on the manufacturing techniques and primary mechanical properties and not on the secondary properties like sound absorption and vibration damping. In this paper, sound absorption and vibration damping properties of flax fiber reinforced composites were characterized and compared with the glass fiber reinforced composites. It was experimentally observed that the sound absorption coefficient of flax fiber reinforced composites has 21.42% & 25% higher than that of glass fiber reinforced composites at higher frequency level (2000 Hz) and lower frequency level (100 Hz). From the vibration study it was observed that the flax fiber reinforced composites have 51.03% higher vibration damping than the glass fiber reinforced composites. The specific flexural strength and specific flexural modulus for flax fiber reinforced composites also good. These results suggest that the flax fiber reinforced composites could be a viable candidate for applications which need good sound and vibration properties.

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Sound and Vibration Damping Properties of Flax Fiber Reinforced Composites

Technical textiles are one of the fastest emergent sectors of textile industries worldwide. Medical textiles and healthcare textiles are the most important development areas within technical textil...

The properties of bioactive substances obtained from seaweeds and their applications in textile industries

This paper analyses a single server batch arrival retrial queue with active breakdowns, two types of repair and second optional service (SOS) The server provides preliminary first essential service (FES) to the primary arriving customers or customers from retrial group The server is subject to breakdowns The customer under service during the failure decides, with probability q, to join the orbit (impatient customer) and, with complementary probability 'p', to remain in the server for repair in order to conclude his remaining service (patient customer) It is considered that the repair time of server during the presence of patient customer and the repair time of the server while the customer (impatient customer) joining the orbit due to failure are different On completion of FES successfully, the customer may opt for SOS with probability α Reliability of the proposed model is analysed Some particular cases are also discussed Other performance measures are also obtained The effects of several parameters on the system are analysed numerically

An MX/G/1 retrial queue with two-phase service subject to active server breakdowns and two types of repair

We consider a single server retrial queue with batch arrivals, two phases of heterogeneous service and a general vacation time under Bernoulli schedule. We carry out steady state system size distribution of number of customers in retrial group, expected number of customers in retrial group and expected waiting time of the customers in the orbit. We discuss its application of the proposed model to the analysis of a communication protocol.

M. Senthil Kumar

Papers

Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates

Sound and Vibration Damping Properties of Flax Fiber Reinforced Composites

The properties of bioactive substances obtained from seaweeds and their applications in textile industries

An MX/G/1 retrial queue with two-phase service subject to active server breakdowns and two types of repair

On the single server batch arrival retrial queue with general vacation time under bernoulli schedule and two phases of heterogeneous service