Application of Headspace Solid-Phase Microextraction and Gas Chromatography for the Analysis of Furfural in Crude Palm Oil

Processing of vegetative material containing pentoses has been shown to result in the formation of furfural. Furfural exhibits a spectrophotometric absorption peak at 518 nm when complexed with aniline acetate. Headspace solid-phase microextraction (HS-SPME) method has been successfully used to confirm the presence of furfural in crude palm oil (CPO). Solid phase microextraction (SPME) fiber composed of divinylbenzene/Carboxen/polydimethylsiloxane (DVB/PDMS/CAR) was used to absorb the volatiles in the headspace of the oil. The isolated compounds from the fiber was desorbed and separated on a capillary polar column of a gas chromatograph. Response surface methodology (RSM) was used to optimize the SPME fiber condition for maximum absorption of furfural from CPO. The optimized temperature and time for furfural extraction onto the SPME fiber are 70 °C for 40 min. Oils obtained from the mill were found to contain between 2 and 13% furfural.     

Ultrasonic infrared thermography in non-destructive testing: A review

Potentials of a novel non-destructive testing technique called ultrasonic infrared thermography (UIT) have been widely recognized for the last decade. This technique is promising for many practical industrial applications being of interest for academic researchers who deal with thermomechanical problems. Significant improvements in the performance of infrared imager have also contributed to increasing popularity of this inspection technique. This paper presents an introduction to the use of UIT in NDT, combining a review of earlier and later research with some experimental illustrations.     

Progress in starch modification in the last decade

Modification of starch is carried out to enhance the positive attributes and eliminate the shortcomings of the native starches. Modification of starch is an ever evolving industry with numerous possibilities to generate novel starches which includes new functional and value added properties as a result of modification and as demanded by the industry. In this paper, we will highlight the many current methods that have been discovered in starch modification which includes four broad areas that are chemical, physical, enzymatical and genetical modification.     

Structure, Superstructure and Charge Order in Bi-Cuprates

Inhomogeneities in any form, affecting either the structural properties as superstructures or the electronic degrees of freedom as stripes, play an essential role in the unusual properties of the cuprates. Bi-cuprates, favored for photoemission studies, are unfortunately prone to structural inhomogeneity and superstructure modulations. We have therefore performed combined STM and high resolution photoemission studies on Bi_2−y Pb _y Sr_2−x La _x CuO_6+δ (Pb-Bi2201) for different compositions and identified the contributions due to superstructures beyond the well-known (1×4.7) reconstruction. Since the inclusion of the related scattering vectors gives a nearly perfect image of the experimental Fermi surface, it can be speculated how far such modeling is necessary to understand the spectral lineshape.     

Expansion and preservation of multipotentiality of rabbit bone-marrow derived mesenchymal stem cells in dextran-based microcarrier spin culture

The use of mesenchymal stem cells (MSCs) in tissue repair and regeneration despite their multipotentiality has been limited by their cell source quantity and decelerating proliferative yield efficiency. A study was thus undertaken to determine the feasibility of using microcarrier beads in spinner flask cultures for MSCs expansion and compared to that of conventional monolayer cultures and static microcarrier cultures. Isolation and characterization of bone marrow derived MSCs were conducted from six adult New Zealand white rabbits. Analysis of cell morphology on microcarriers and culture plates at different time points (D0, D3, D10, D14) during cell culture were performed using scanning electron microscopy and bright field microscopy. Cell proliferation rates and cell number were measured over a period of 14 days, respectively followed by post-expansion characterization. MTT proliferation assay demonstrated a 3.20 fold increase in cell proliferation rates in MSCs cultured on microcarriers in spinner flask as compared to monolayer cultures (p < 0.05). Cell counts at day 14 were higher in those seeded on stirred microcarrier cultures (6.24 ± 0.0420 cells/ml) × 10⁵ as compared to monolayer cultures (0.22 ± 0.004 cells/ml) × 10⁵ and static microcarrier cultures (0.20 ± 0.002 cells/ml) × 10⁵. Scanning electron microscopy demonstrated an increase in cell colonization of the cells on the microcarriers in stirred cultures. Bead-expanded MSCs were successfully differentiated into osteogenic and chondrogenic lineages. This system offers an improved and efficient alternative for culturing MSCs with preservation to their phenotype and multipotentiality.     

Fatigue crack growth simulation of aluminium alloy under spectrum loadings

Fatigue crack growth in structure components, which is subjected to variable amplitude loading, is a very complex subject. Studying of fatigue crack growth rate and fatigue life calculation under spectrum loading is vital in life prediction of engineering structures at higher reliability. The main aim of this paper is to address how to characterize the load sequence effects in fatigue crack propagation under variable amplitude loading. Thus, a fatigue life under various load spectra, which was predicted, based on the Austen, Forman and NASGRO models. The findings were then compared to the similar results using FASTRAN and AFGROW codes. These models are validated with the literature-based fatigue crack growth test data in 2024-T3 Aluminium alloys under various overload, underload, and spectrum loadings. With the consideration of the load cycle interactions, finally, the results show a good agreement in the behaviour with small differences in fatigue life compare to the test data.     

Crashworthiness characteristics investigation of silk/epoxy composite square tubes

This research concentrates on the evaluation of crashworthiness characteristics of natural silk/epoxy composite square tubes energy-absorbers. Composite laminate specimens were subjected to static axial compression load and experimental evaluation of the energy absorption capability of silk/epoxy composite. Specimens were in the form of square cross-sections with the dimension of 80 mm × 80 mm and a radius curvature of 5 mm. The variables in the experiment were the length of the tubes built 50 mm, 80 mm and 120 mm. Meanwhile, the thickness of the walls, consisting of laminates of silk/epoxy of 12, 24 and 30 plies, correspond to equivalent wall thickness of 1.7 mm, 3.4 mm and 4.2 mm, respectively. The parameters measured were the total absorbed energy (E_total), and the crash force efficiency (CFE). E_total is the measure of the amount of energy that the structure can withstand without failure and thus is a measure of its strength, while CFE gives a quantitative indication of the mode of failure of the composites. The mode of failure was observed using photography.     

Inverse analysis using particle swarm optimization for detecting corrosion profile of rebar in concrete structure

In this paper, inverse analysis with the use of Particle Swarm Optimization (PSO) is developed for detecting the corrosion of reinforcing steel in concrete from a relatively small number of potential data measured on the concrete surface. PSO is a promising optimization method due to its simplicity of programming and comparable accuracy. In this proposed inverse analysis using PSO, corrosion profiles represent the location and size of reinforcing steel corrosion. In this method, candidate solution is modeled as a swarm of particles. The objective function, which is proportional to the cost function, is evaluated for the swarm of particles. This function is the difference between the calculated and measured potentials on the concrete surface. The calculated potentials on the surface of the concrete are obtained by solving the Laplace's equation by using the Boundary Element Method (BEM). The corroded and non-corroded parts of the reinforcing steel are represented by each polarization curve. Inverse analysis is carried out by minimizing the cost function using PSO. Examples of the numerical simulation were used to demonstrate the effectiveness of the proposed method. It shows that proposed inverse analysis had promising capability in detecting the corrosion profile of reinforcing steel in concrete.     

An investigation on the optimum machinability of NiTi based shape memory alloy

In the present work, the machinability of nickel–titanium (Nitinol) shape memory alloy has been discussed. Nitinol is known as a difficult-to-machine alloy due to its high hardness, which requires a large amount of cutting force, resulting in high rate of tool wearing. Therefore, researchers have made an effort to ameliorate the machinability of this material to achieve a finer surface quality. The previous studies found that the cutting speed will remarkably influence the surface properties of machined nickel–titanium alloy in turning process. Tool wear and cutting force are at minimum values in a particular range of cutting speeds so that it leads to diminishing machining barriers such as burr formation and chip-breaking. Lower cutting force and consequently lower temperature and stresses in the machining process improve the mechanical properties as well as reducing hardness, distortion, and residual stress. The machining process was optimized by applying a numerical approach through ANSYS/LS-DYNA R15 software. The obtained results demonstrated the optimum cutting speed in the machining process, which are in good agreement with experiments.     

Modeling of fatigue crack propagation using dual boundary element method and Gaussian Monte Carlo method

This paper studies the modeling of fatigue crack propagation on a multiple crack site of a finite plate using deterministic and probabilistic methods. Stress intensity factor has been calculated by the combined deterministic approach of the dual boundary element method (DBEM) and the probabilistic approach of the Gaussian Monte Carlo method. The Gaussian Monte Carlo method has been incorporated to simulate the random process of the fatigue crack propagation. A finite plate of aluminum alloy 2024-T3 with a thickness of 1.6 mm and 14 holes is analyzed and the fatigue life of the plate is predicted by following a linear elastic law of fracture mechanics. The results of fatigue life predicted by DBEM-Monte Carlo method are in good agreement with experimental ones. The same approach is also applied to two other engineering applications of a gear tooth and a bracket.