Biogenic copper nanoparticles promote the growth of pigeon pea (Cajanus cajan L.)

Environmental pollution and toxicity have been increasing due to the overuse of chemical fertilisers, which has encouraged nanotechnologists to develop eco‐friendly nano‐biofertilisers. The authors demonstrated the effect of biogenic copper nanoparticles (CuNPs) on the growth of pigeon pea (Cajanus cajan L.). The UV–visible analysis showed absorbance at 615 nm. Nanoparticle tracking and analysis revealed particle concentration of 2.18 × 10⁸ particles/ml, with an average size of 33 nm. Zeta potential was found to be −16.7 mV, which showed stability. X‐ray diffraction pattern depicted the face centred cubic structure of CuNPs; Fourier transform infrared spectroscopy demonstrated the capping due to acidic groups, and transmission electron micrograph showed nanoparticles with size 20–30 nm. The effect of CuNPs (20 ppm) on plant growth was studied, for the absorption of CuNPs by plants on photosynthesis, which was evaluated by measuring chlorophyll a fluorescence using Handy‐Plant Efficiency Analyser. CuNPs treatment showed a remarkable increase in height, root length, fresh and dry weights and performance index of seedlings. The overall growth of plants treated with CuNPs after 4 weeks was recorded. The results revealed that inoculation of CuNPs contribute growth and development of pigeon pea due to growth promoting activity of CuNPs.Inspec keywords: pollution, toxicology, nanotechnology, cropsOther keywords: biogenic copper nanoparticles, pigeon pea, Cajanus cajan L, environmental pollution, toxicity, chemical fertilisers, nanotechnologists, eco‐friendly nano‐biofertilisers, cash crop, UV‐visible analysis, nanoparticle tracking, zeta potential, X‐ray diffraction pattern, Fourier transform infrared spectroscopy, acidic groups, transmission electron micrograph, photosynthesis, chlorophyll, fluorescence, Handy‐Plant Efficiency Analyser, performance index     

Ultrasonic Lamb wave based monitoring of corrosion type of damage in plate using a circular array of piezoelectric transducers

In this paper we propose a concept and report experimental results based on a circular array of Piezoelectric Wafer Active Sensors (PWASs) for rapid localization and parametric identification of corrosion type damage in metallic plates. Implementation of this circular array of PWASs combines the use of ultrasonic Lamb wave propagation technique and an algorithm based on symmetry breaking in the signal pattern to locate and monitor the growth of a corrosion pit on a metallic plate. Wavelet time-frequency maps of the sensor signals are employed to obtain an insight regarding the effect of corrosion growth on the Lamb wave transmission in time-frequency scale. We present here a method to eliminate the time scale, which helps in identifying easily the signature of damage in the measured signals. The proposed method becomes useful in determining the approximate location of the damage with respect to the location of three neighboring sensors in the circular array. A cumulative damage index is computed from the wavelet coefficients for varying damage sizes and the results appear promising. Damage index is plotted against the damage parameters for frequency sweep of the excitation signal (a windowed sine signal). Results of corrosion damage are compared with circular holes of various sizes to demonstrate the applicability of present method to different types of damage.     

Explicit stiffness matrices of the lagrange rectangular prism elements for three dimensional problems

A simple and convenient way to generate stiffness matrices in closed form for all members of the three dimensional rectangular prism elements of the Lagrange family is presented. For all elements of a given order irrespective of their sizes and material properties just three basic matrices of numbers are obtained. These matrices are then manipulated in a simple manner to compute triple integrals of shape function derivatives which are required to form element stiffness matrices of linear three-dimensional elasticity problems. Numerical values of all triple integrals for linear, quadratic and cubic rectangular prism elements are tabulated for immediate use.     

Boron nitride and fluoropolymer combinations: Interactions and their performance as processing aids

In this work, we studied the adsorption capacity of boron nitride (BN) for fluoropolymer and polyethylene (PE) to gain a better understanding of the interactions and the performance of BN and fluoropolymer, and their combinations as processing aids in the extrusion of Ziegler‐Natta PEs. We found that BN has a relatively high adsorption capacity for both PE and fluoropolymer. As a result, simultaneous compounding of BN and fluoropolymer into the host polymer causes fluoropolymer to be trapped within the bulk of the polymer, and prevents the fluoropolymer particles from coating the die wall during flow. This limits the effectiveness of fluoropolymer and BN as processing aids. To avoid this interaction, we added fluoropolymer separately in a dry form just prior to extrusion. In this case, the synergistic effect of BN and fluoropolymer as a combination processing aid was evident. POLYM. ENG. SCI., 45:669–677, 2005. © 2005 Society of Plastics Engineers     

Electrical performance study of 25 nm Ω-FinFET under the influence of gamma radiation: A 3D simulation

In this research paper, a 3D process simulation of 25 nm n-channel Ω-FinFET and the effect of Gamma radiation on device characteristics have been studied. Device simulations are carried out under the influence of Gamma radiation under varying does conditions from 100 Krad (SiO₂) to 10 Mrad (SiO₂). Effects of Gamma radiation on the threshold voltage, transfer characteristics, drive current, off-state leakage current and subthreshold characteristics have been studied. Extracted parameters for virgin and irradiated devices have been compared in order to understand the degradation in the electrical characteristics of the Ω-FinFET under study. Simulation results under the low drain and high drain bias has been reported and discussed. It is found that Ω-FinFET delivers better performance under irradiation as compared with conventional single gate MOS structures. Ω-FinFET is shown to be significantly tolerant to gamma radiation upto dose of 5 Mrad (SiO₂). In addition, the influence of quantum effects on this nanoscale device is investigated in detail. Sentaurus simulation results obtained has been compared with the reported experimental data.     

The effect of nanoclays on the processibility of polyolefins

The influence of a new processing additive (particles of organically modified nanoclays) on the processibility of polyolefins in extrusion is studied. The equipment used includes an Instron capillary rheometer with two types of dies, namely capillary dies and special annular dies (Nokia Maillefer wire coating crosshead) attached to the rheometer. Ziegler Natta and metallocene polyethylenes and one polypropylene were tested using these two pieces of equipment. It was found that the nanoclay additive had a significant effect on the extrudate appearance of polyethylene. It eliminates surface melt fracture and postpones the critical shear rate for the onset of gross melt fracture to significantly higher values depending on resin type, temperature, and additive concentration (typically 0.05 to 0.5 wt%). To explain the possible mechanism for the effect of the additive on the processibility of the resins, shear and extensional rheological measurements were carried out for the pure resins as well those loaded with the nanoclay additives. It seems that the presence of nanoclays suppresses the development of extensional stresses to such high levels that can cause melt fracture phenomena. Finally, it was found that the combination of nanoclays with traditional processing aids such as fluoropolymers produce an enhanced processing aid that can increase the critical shear rates for the onset of melt fracture to levels much higher than the individual constituents when they are used independently. POLYM. ENG. SCI., 45:1098–1107, 2005. © 2005 Society of Plastics Engineers     

The effect of surface energy of boron nitride on polymer processability

Flow instabilities manifest themselves as distortions on the extrudate surface (melt fracture). They are usually observed at high production rates in many polymer processing operations. Certain fluoropolymers/fluoroelastomers have long been used as processing aids for surface melt fracture elimination. Recent developments have shown that a small amount of boron nitride (BN) powder may successfully eliminate surface melt fracture and also delay the onset of gross melt fracture to higher rates. It has also been reported that a combination of BN and fluoropolymer/fluoroelastomer enhances the effectiveness of the polymer processing even further. The main objective of the present work was to measure the surface properties of a number BN powders, mainly surface energy, in order to gain a better understanding of its performance as a processing aid. Based on this study, it can be concluded that surface energy plays an important role in deciding the possible interactions between the processing aid, polymer melt and the extruding surface. It is observed that the lubricious nature of BN along with an optimum balance of its polar (non‐dispersive) and non‐polar (dispersive) components of surface energy renders BN a successful processing aid in eliminating both sharkskin and gross melt fracture phenomena. Polym. Eng. Sci. 44:1543–1550, 2004. © 2004 Society of Plastics Engineers.     

A study of asymmetrically loaded griffith crack in an infinite anisotropic medium

The two dimensional problem of a Griffith type crack whose surfaces are subjected to asymmetrical loading in an infinite anisotropic elastic medium is studied. The analysis is based on the integral transform method and the finite Hubert transform technique of dual integral equations. Closed form solutions of displacement components along the line of the crack and the formulae for the stress components at a general point are obtained. The near crack tip approximations to stress components are also presented in detail.     

Heat transfer intensification in horizontal shell and tube latent heat storage unit

Employment of latent heat storage unit (LHSU) utilizing phase change material (PCM) in a substantial scale is constrained by the poor thermal conductivity of PCMs. Future utilization of LHSU will therefore to a great extent rely on the heat transfer intensification techniques. Present research is on enhancement techniques in which heat transfer mechanism is altered without altering the mass of PCM and heat transfer surface area. The intensification mechanisms considered in the present research include imparting eccentricity to heat transfer fluid (HTF) pipe, imparting rotation to the LHSU and providing multi HTF tube. Numerical investigations are reported here towards comparative evaluation of the thermal characteristics associated with such intensification mechanisms for horizontal LHSU. In the present study stearic acid (melting point 55.7–56.6?°C) is used as PCM and water is used as HTF. Results infer that all the three mechanisms offer quicker melting rate. For the geometric configuration of LHSU considered in the present research, a reduction in melting time of 47.75% is evaluated for rotating LHSU. The rate of energy storage is higher for both eccentric and rotating LHSU. Solidification process is however not accelerated by such techniques. On the contrary, eccentric and multi HTF tube LHSU takes more time for solidification.