Green synthesised iron and iron‐based nanoparticle in environmental and biomedical application: – a review

Owing to the development of nanotechnology and its influence in various fields, the development of efficient and environmental friendly technique for the synthesis of nanomaterials is important. Among the various traditional and conventional methods available for the synthesis, plant‐mediated synthesis seems to be a very attractive and environmental friendly method, attributing to its simple methodology and eco‐friendly approach. The synthesis rate and stability of the nanoparticle synthesised are good when compared to the other methods of synthesis and it is proved to be efficient in various fields of application. Hence, the present review article deals with furnishing information about the plant sources used so far and details about the environmental and biomedical applications of the synthesised nanoparticles.Inspec keywords: nanoparticles, reviews, nanomedicine, nanofabrication, antibacterial activity, ironOther keywords: environmental application, biomedical application, iron‐based nanoparticle, environmental friendly technique, traditional methods, plant‐mediated synthesis, environmental friendly method, simple methodology, eco‐friendly approach, synthesis rate, nanoparticle stability, green synthesis, nanotechnology, nanomaterials, conventional methods, Fe     

Variation in Properties of Starch in Cassava Varieties in Relation to Age of the Crop

Cassava starch extracted from six varieties at different period of growth was examined for various physiochemical properties. The granule size increased in all the six varieties upto 6th month from time of tuber initiation and thereafter remained almost constant. The amylose content and reducing values did not vary much at different stages of growth. The swelling volume and swelling power of starch showed large variations particularly after 10th month. Such changes of four varieties were not noticed in other varieties. Associative binding forces of starch molecules largely determine the stability characteristics of starch under varied environmental conditions.     

Investigation of kinetics of 4‐methylpentene‐1 polymerization using Ziegler–Natta‐type catalysts

The kinetics of 4‐methylpentene‐1 (4MP1) polymerization by use of Ziegler–Natta‐type catalyst systems, M(acac)₃‐AlEt₃ (M = Cr, Mn, Fe, and Co), are investigated in benzene medium at 40°C. The effect of various parameters such as Al/M ratio, reaction time, aging time, temperature, catalyst, and monomer concentrations on the rate of polymerization and yield are examined. The rate of polymerization increased linearly with increasing monomer concentration with first‐order dependence, whereas the rate of polymerization with respect to catalyst concentration is found to be 0.5. For all cases, the polymer yield is maximum at an Al/M ratio of 2. The activation energies obtained from linear Arrhenius plots are in the range of 25.27–33.51 kJ mol^?1. It is found that the aging time to give maximum percentage yield of the polymer varies with the catalyst systems. Based on the experimental results, a plausible mechanism is proposed that envisages a free‐radical mechanism. Characterization of the resulting polymer product, for all the cases, through FTIR, ¹H‐NMR, and ¹³C‐NMR studies, showed isomerized polymeric structures with 1,4‐structure as dominant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2468–2477, 2003     

Optimum design parameters of a squash head projectile

This note first establishes a correlation between post impact fuze delay and the spread of explosives of a squash head gun-fired projectile when hitting a rigid non-yielding plate. Estimations of optimum strike velocity and fuze delay to maximize spread are derived.     

Compiler-directed scratch pad memory optimization for embedded multiprocessors

This paper presents a compiler strategy to optimize data accesses in regular array-intensive applications running on embedded multiprocessor environments. Specifically, we propose an optimization algorithm that targets at reducing extra off-chip memory accesses caused by interprocessor communication. This is achieved by increasing the application-wide reuse of data that resides in scratch-pad memories of processors. Our results obtained using four array-intensive image processing applications indicate that exploiting interprocessor data sharing can reduce energy-delay product significantly on a four-processor embedded system.     

Corrosion-induced bond strength degradation in reinforced concrete—Analytical and empirical models

The present paper aims to investigate the relationship between the bond strength and the reinforcement corrosion in reinforced concrete (RC). Analytical and empirical models are proposed for the bond strength of corroded reinforcing bars. Analytical model proposed by Cairns.and Abdullah [Cairns, J., Abdullah, R.B., 1996. Bond strength of black and epoxy-coated reinforcement—a theoretical approach. ACI Mater. J. 93 (4), 362–369] for splitting bond failure and later modified by Coronelli [Coronelli, D. 2002. Corrosion cracking and bond strength modeling for corroded bars in reinforced concrete. ACI Struct. J. 99 (3), 267–276] to consider the corroded bars, has been adopted. Estimation of the various parameters in the earlier analytical model has been proposed by the present authors. These parameters include corrosion pressure due to expansive action of corrosion products, modeling of tensile behaviour of cracked concrete and adhesion and friction coefficient between the corroded bar and cracked concrete. Simple empirical models are also proposed to evaluate the reduction in bond strength as a function of reinforcement corrosion in RC specimens. These empirical models are proposed by considering a wide range of published experimental investigations related to the bond degradation in RC specimens due to reinforcement corrosion. It has been found that the proposed analytical and empirical bond models are capable of providing the estimates of predicted bond strength of corroded reinforcement that are in reasonably good agreement with the experimentally observed values and with those of the other reported published data on analytical and empirical predictions. An attempt has also been made to evaluate the flexural strength of RC beams with corroded reinforcement failing in bond. It has also been found that the analytical predictions for the flexural strength of RC beams based on the proposed bond degradation models are in agreement with those of the experimentally observed and the empirically predicted values of the reported published data (Mangat, P.S., Elgarf, M.S. 1999a. Flexural strength of concrete beams with corroding reinforcement. ACI Struct. J. 96 (1), 149–158).     

Vinyl polymerization by Ziegler catalysts

Summary Methylmethacrylate and styrene were polymerized with Co(acac)₃-AlEt₂ Br catalyst system in benzene at 40°C. Rate of polymerization is linear to monomer concentrations. Maximum percent conversion of polymer was obtained when Al/Co2 with styrene and Al/Co3 with methylmethacrylate. With increase in aging time catalytic activity decreases. Activation energy was found to be 60 KJ mol^–1. with styrene and 40 KJ mol^–1. with methylmethacrylate.The authors arc thankful to the UGC, INDIA for the financial support.     

A comparative study of the kinetic theories of the glass transition phenomenon in high polymers

The effect of thermal history on the glass transition temperature (T_g) of poly(vinyl chloride) was studied. The parameters like the hole energy (E_h), the activation energy for the disappearance of holes (E_j), the activation enthalpy for the structural relaxation (Δh1* and Δh2*) and the activation energy for the glass transition process (E) were calculated. The increase of E_h value with the increase in T_g value shows that there exists a holesize distribution. The E_j (26.9 ± 0.5 kcal/mol) value calculated according to Wunderlich's treatment, the Δh1* (27.8 ± 0.6 kcal/mol) value obtained by Moynihan's procedure and the E (35.3 kcal/mol) value from Barton-Critchley's method agree well with one another in the poly(vinyl chloride) system. The Δh2* quantity, obtained through Moynihan's formulations, increase as the rate of heating was increased, a result similar to the variation of E_h value with the rate of heating.     

Development of a slurry injection technique for continuous fibre ultra-high temperature ceramic matrix composites

A simple and effective slurry injection method for producing dense and uniform ultra-high ceramic matrix composites from preforms of high fibre density was developed. As this method is based on slurry injection the homogeneity is not constrained to small preform sizes; dense components of high fibre volume can be produced in theoretically any size and shape. Samples produced by this method demonstrated high and consistent densities, with the injection method obtaining densities an average 27% higher and 87% lower in variability when compared to conventional vacuum impregnation. Tomography demonstrated no bias in the ceramic powder distribution for samples produced by injection, whereas samples produced by vacuum impregnation alone displayed poor powder penetration to the centre of large samples. The new approach yielded composites that were as strong and/or more consistent in strength compared to vacuum impregnation. Thermo-ablative testing demonstrated significant improvements in protective capability for materials produced by this route.     

Dual rotating compensator ellipsometry: Theory and simulations

Systematic methods for data reduction have been developed for the dual rotating-compensator ellipsometer in the PC_1r(ω₁)SC_2r(ω₂)A configuration, where P, C_1r(ω₁), S, C_2r(ω₂), and A represent the polarizer, first rotating compensator, reflecting sample, second rotating compensator, and analyzer, respectively. The approach used here is more general than previous treatments in that it incorporates dichroic compensators that rotate synchronously at a frequency ratio ω₁:ω₂ of p:q, where p and q are integers. For specific frequency ratios, the 24 ac Fourier coefficients of the irradiance waveform at the detector over-determine the 15 real elements of the (1,1)-normalized Mueller matrix and the 3 complex elements of the (2,2)-normalized Jones matrix. Alternative data reduction approaches resulting from this capability of over-determination are shown through numerical simulations to have different performance characteristics under non-ideal experimental conditions. Finally, the importance of using an achromatic retarder design in the dual rotating-compensator ellipsometer is emphasized through these simulations.