Color intensity and wash fastness properties of dyed cotton fabric after plasma treatment

In this research work, first cotton fabrics were dyed with various types of dyestuffs such as vat, reactive, and direct and then dyed fabrics were treated with low-temperature plasma (LTP) of nitrogen, air, and argon gases, and some properties of the samples were investigated. Color intensities of the dyed fabrics were measured using a UV VIS-NIR Reflective Spectrophotometer, over the range of 200–800 nm. Water drop test and wash fastness determination (ISO 105-C01) were conducted. The results show that post-plasma treatment of direct dyed cotton fabric can be a useful method for improving the fastness properties of direct dyed cotton samples. Also, by post-plasma treatment with argon gas, water repellent effect appeared for all samples.     

Interference‐resilient spectrum sharing with collision detection and data recovery for cognitive radio networks

Data recovery under collision of primary/secondary users in cognitive radio networks is largely an unaddressed problem. Existing approaches require either (a) retransmissions, (b) interference‐free alignment of transmission parameters, or (c) prior knowledge for data recovery. In contrast to the existing approaches, the paper proposes estimation of channel state information based on received collided frames and recommends techniques for spectrum sharing, collision detection, and data recovery. Specifically, based on estimated channel vector, interference‐resilient spectrum‐sharing protocol and techniques are proposed for (a) identification of primary user (PU) activity before (or during) secondary user's (SU's) transmission, (b) MIMO channel estimation under collision, (c) optimal pilot permutation, and (d) interference cancellation (with/without receiver diversity). Results are reported for different baseband modulation techniques under frequency selective/flat fading channel scenarios that demonstrate the efficacy of a proposed work.     

The effect of ethoxylated nonyl phenols on the interfacial tension between crude oil and water

In this study, the effect of ethoxylated nonyl phenols with ethoxy group numbers 4 and 9 (nonyl phenol 4 and nonyl phenol 9), were investigated on the interfacial tension between crude oil and water. The interfacial tensions decreased significantly in a concentration range of 0–1.25 g.l^–1. By increasing sodium chloride concentration, the time which was required to reach equilibrium interfacial tension was reduced. Therefore, sodium chloride affected the dynamic interfacial tension. However, ethoxylated nonyl phenols resisted against change of salinity. The effect of mixed surfactants on the decreasing of the interfacial tension was more than an individual surfactant, because of the synergism. The most effective mixture of a two surfactants system was observed when mass ratio of nonyl phenol 9 and nonyl phenol 4 was 0.5.     

Pressure waves in bubbly liquids

It is well known that sound propagation in liquid media is strongly affected by the presence of gas bubbles that interact with sound and in turn affect the medium. An explicit form of a wave equation in a bubbly liquid medium was obtained in this study. Using the linearized wave equation and the Keller-Miksis equation for bubble wall motion, a dispersion relation for the linear pressure wave propagation in bubbly liquids was obtained. It was found that attenuation of the waves in bubbly liquid occurs due to the viscosity and the heat transfer from/to the bubble. In particular, at the lower frequency region, the thermal diffusion has a considerable affect on the frequencydependent attenuation coefficients. The phase velocity and the attenuation coefficient obtained from the dispersion relation are in good agreement with the observed values in all sound frequency ranges from kHz to MHz.     

Transesterification of oil extracted from freshwater algae for biodiesel production

Currently, energy crisis is a burning issue throughout the world, particularly in underdeveloped countries like Pakistan where the demand of conventional fuels has been increasing day by day. The main objective of this project was the production of biodiesel from Algae. Samples of freshwater were collected. The Chlorella species produced 6.26 g oil from 38.23 g of dry weight and the Oedogonium species produced 8.07 g of oil from 38.23 g of dried weight. The biomass obtained after oil extraction was 31.97 g from chlorella species and 30.16 g from Oedogonium species. The fatty acids that were displayed by a gas chromatographic machine in chlorella species were capric acid, nanoic acid, arachidonic acid, behenic acid, and erucic acid and in oedogonium species they were capric acid, butyric acid, behenic acid, luric acid, tridecanoic acid, and arachidonic acid.