Modeling Water Flow Through Carbon Nanotube Membranes with Entrance/Exit Effects

Carbon nanotube–based membranes have gained significant attention due to their transport efficiency and wide range of applications, including molecular sieving and sensing. Recently, in order to attain high transport rates, many studies have focused on reducing membrane thickness. A reduction in membrane thickness results in the dominance of entrance/exit effects over surface effects, particularly for carbon nanotubes (CNTs), due to their hydrophobicity. However, experimentally obtained nanoscale flow rate data span a wide range, and entrance/exit effects are often neglected when analyzing these data. In this study, we modeled the water flow rate through various lengths and radii of CNTs using molecular dynamics simulations while also taking entrance/exit effects into consideration. Based on viscosity and slip length calculations, a water flow model is proposed that covers various lengths and radii of CNTs. Moreover, the enhancement factor of CNT membranes is reassessed using entrance/exit effects. The results of this study can be used for the optimal design of ultraefficient CNT membranes for potential applications such as water filtration.     

Characterisation of Seed Lipids from Bixa orellana and Trachyspermum copticum

Bixa orellana L. seeds possess a resinous lipid (6.3 %), which has a pungent and spicy odour. The seed is known for its medicinal properties such as anti‐inflammatory, antipyretic activity and as a cure for tonsilitis. Trachyspermum copticum L. seed is a well known digestive aid and relief from colic pain. T. copticum possesses essential oil rich in thymol (>50 %) and lipid (15.6 %). The present study was aimed to quantify lipid classes of these two species by silicic acid chromatography and analyze their fatty acid composition by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). It was observed that the seed lipids are rich in neutral lipids with 98.1 and 95.2 % and lower quantities of glycolipids of 1.5 and 3.8 % and phospholipids of 0.36 and 1.0 % in B. orellana and T. copticum, respectively. The fatty acid composition of B. orellana seed lipid showed major quantities of palmitic (26.9 %), linoleic (26.1 %), oleic (17.5 %), linolenic (15.1 %), stearic acid (10.8 %) and small quantities of eicosanoic acid (3.6 %). In T. copticum seed lipids, petroselinic acid (68.3 %) and linoleic acid (25.3 %) together constituted 93 % of the total lipid. The results revealed that the lipids after recovery of the essential components namely, bixin and volatile oil from B. orellana and T. copticum, respectively can be further explored for industrial applications.     

Tensile and Fracture Properties of Aluminium Alloy AA2219-T87 Friction Stir Weld Joints for Aerospace Applications

Metallurgical and Materials Transactions A - The purpose of the present work is to study the mechanical behaviour of AA2219-T87 friction stir weld (FSW) joints at different temperatures (Room...     

Estimation of Effect of Fog on Terrestrial Free Space Optical Communication Link

Wireless Personal Communications - Free Space Optical Communication Technology is expected as the successor to the existing communication technologies as many of its features like high bandwidth,...     

Failure Analysis of AISI 440C Steel Ball Screws Used in the Actuator System of a Satellite Launch Vehicle

In view of its excellent wear and corrosion resistance, AISI 440C steel is the material of choice for the fabrication of ball screws used in actuator systems of satellite launch vehicles. During the routine acceptance test of a ball screw, longitudinal cracks were observed at the shaft location of the ball screw. The optical microstructure of the ball screw material (AISI 440C) revealed the presence of aligned carbides (carbide banding). Fractographic observations revealed the cracking to be along the carbide bands. Based on detailed optical and scanning electron microscopic observations, the cracking of the ball screws was attributed to the carbide bands.     

SOLUTION OF TRANSIENT LAMINAR NATURAL CONVECTION IN A SQUARE CAVITY BY AN EXPLICIT FINITE ELEMENT SCHEME

This paper discusses the application of a finite element method based on the first-order projection scheme, which is an extension ofChorin's algorithm, to transient laminar natural convection in a square cavity. Results have been presented for a fluid of Prandtl number 0.71 in the Rayleigh number range of 10³-10⁶ in terms of the variation of vertical velocity component, nondimensional temperature, and average Nusselt number with time. Various features of the scheme that render it economical in terms of CPU time and storage requirements are discussed. The steady state results have been compared with benchmark solutions, and the agreement appears to be good.     

Two-beam interference experiments in the frequencydomain to measure the complex degree of spectral coherence

Abstract

Correlation-induced spectral changes in two-beam interference experiments in the space-frequency domain are used to determine the amplitude and phase of the complex degree of spectral coherence. The spectral modifications are observed either as a shift in the peak wavelength or as sinusoidal modulations within the bandwidth of the white light spectrum due to the complex degree of spectral coherence of the secondary source and the path difference between the interfering beams. These correlation-induced spectral changes were analysed using a theoretical model to establish the behaviour of the real and imaginary parts of the complex degree of spectral coherence over the entire visible region of the spectrum.