Forthcoming Issue

Vol. 29, No. 1 (April 2018)

1. Assessment of Jatropha Oil as Insulating Fluid for Power Transformers (Abdelghaffar Amoka Abdelmalik, Paul Adeoluwa Abolaji and Hamzah Abubakar Sadiq)

Abstract: Seed-based oil has been identified as a viable alternative insulating fluid and a number of vegetable oil has been studied for that purpose. Among the seed-based oils studied is Jatropha oil which was reported to have suitable breakdown strength for high voltage application. However, most of the reports failed to study the ageing characteristics of the oil and its compatibility with cellulose insulation. In this present study, the properties and ageing behaviour of a freshly prepared Jatropha oil and its compatibility with cellulose insulation paper was evaluated. The oil was purified by modified Dijkstra and Opstal purification method. The thermo‑physical and dielectric studies of the oil was performed and thermal ageing of Kraft paper in the prepared ester fluid was performed. Thermally accelerated ageing was performed with an open beaker containing ageing catalysts, thermally upgraded insulation paper, and the fluid at 140°C for 120, 240, 360 and 480 h. Jatropha oil is a high temperature fluid with high specific heat capacity of 2.59 kJ kg-1 K and low dielectric loss of 0.009. The oil became polymerised with ageing in open cup. This may be due to thermo‑oxidative degradation of the oil with progressed with ageing time. This is an indication that the oil is not suitable for use in free breathing power equipment.

2. Development and Performance Investigation of Energy Recovery System in Tropical Climate (Chiau Yong Tang, Mardiana Idayu Ahmad and Yusri Yusup)

Abstract: With the global primary energy consumption and carbon dioxide emissions elevating 2% and 1.7% annually, it is critical to install energy recovery systems in buildings for better energy conservation. Due to limited research on the energy recovery system in the tropical climate, this study presents the development and performance investigation of an energy recovery system in the tropical climate region. The hydrophilic polymeric membrane of the heat exchanger core was developed and organised in a cross-flow manner. Performance investigation was carried out for several operating parameters, temperature, relative humidity and air velocity. It was found that there were negative relationships between air velocity and efficiency, temperature and humidity ratio differences with increasing residence time. Ranges of latent and sensible efficiencies were 42%-74% and 45%-78%, respectively. The highest sensible energy recovered was 18 kW at the temperature intake of 40ºC. One-way ANOVA showed that the air velocity significantly affects sensible and latent efficiencies at different temperature intakes.

3. Diffusion of Cu Ions into Nanoclay by Molten Salt Ion Exchange for Antibacterial Application (Afsaneh Nouri, Mohammad Ghorbanpour and Samaneh Lotfiman)

Abstract: Novel Cu/nanoclay composites with antibacterial activity were synthesised by molten salt ion exchange method at two temperatures and at different times. The produced composites were characterised using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The antibacterial activity of these composites was assayed by the disc inhibition method. X-ray diffraction patterns indicate that nanoclay has a d-spacing (1.44 nm), higher than Cu/nanoclay composites (1.34-1.37 nm). This result implies that copper nanoparticles could exist in microspores of nanoclay. On the other hand, the UV-Vis findings confirm that no copper in the form of sulfate existed in the obtained composites. The antibacterial activity of Cu/nanoclay nanocomposites against Escherichia coli and Staphylococcus aureus showed efficient bactericidal effect. On the other hand, results demonstrate that the antibacterial activity of the resultant composites does not depend on ion exchange time and temperature. Thus, the resultant composites show high stability that can last for a long time. The produced composites by this novel method can be used to synthesise nanoclay composite with antibacterial activity for various applications such as water treatment and biodegradable composites.

4. Mechanical and Oxygen Barrier Properties of LDPE/MMT/MAPE and LDPE/MMT/EVA Nanocomposite Films: A Comparison Study (Khaliq Majeed, Reza Arjmandi and Azman Hassan)

Abstract: Enhanced mechanical and barrier properties are of special interest in food packaging industries, in which uniform dispersion of nanoparticles in polymers confers considerable improvement in these properties. In this study, maleic anhydride grafted polyethylene (MAPE) and ethylene vinyl acetate (EVA) compatibilised low density polyethylene/montmorillonite (LDPE/MMT) nanocomposite films were prepared with different concentrations of the compatibilisers by melt mixing technique. The delamination of MMT layers was evidenced from X-ray diffraction results that suggested an increase in the interlayer distance with the addition of compatibilisers, where MAPE is the better compatibiliser in delaminating MMT platelets in LDPE/MMT nanocomposites compared to EVA. The mechanical and barrier properties of compatibilised LDPE/MMT nanocomposites were better than uncompatibilised nanocomposites. The best improvement in tensile strength, tear strength and oxygen barrier were observed for LDPE/MMT/MAPE nanocomposites. However, the best improvements in elongation at break were seen for the LDPE/MMT nanocomposites compatibilised with EVA. Conclusively, MAPE compatibiliser is more effective in delaminating MMT platelets in LDPE/MMT nanocomposites; enhancing the mechanical and barrier properties of the nanocomposites. Results revealed that the optimum content of MAPE in terms of mechanical and barrier properties is 3 phc. The enhanced tensile and barrier properties of LDPE/MMT films with the incorporation of MAPE suggest a great potential of these nanocomposite films in food packaging.

5. Properties of Particleboard Made from Oil Palm Trunks Added Magnesium Oxide as Fire Retardant (Teh Yun Hui, Mohd Ezwan Selamat, Rokiah Hashim, Othman Sulaiman, Mohamad Haafiz Mohamad Kassim and Natra Joseph Stalin)

Abstract: The aim of this study is to evaluate the physical, mechanical and flame retardant properties of particleboard made from oil palm trunk (OPT) with the addition of magnesium oxide as flame retardant. The physical and mechanical properties of the particleboard were evaluated based on Japanese Industrial Standard (JIS A 5908) and the flame retardant properties were determined according to International Standards Organization (ISO 4589). The particleboard was manufactured to a target density 0.80 g cm-3 with addition of magnesium oxide (0 %, 10 % and 20 %). The results showed the thickness swelling and water absorption of treated particleboard decreased as the percentage of magnesium oxide increased. The untreated OPT particleboard without any flame retardant showed better mechanical strength. For thermogravimetric analysis (TGA), the treated OPT particleboard showed better thermal stability compared with the untreated OPT particleboard. The OPT particleboard treated with 20% magnesium oxide showed better flame retardant properties compared to the control and 10% magnesium oxide sample that satisfied the ISO 4589 standard requirement.

6. Protection of Aluminium Metal in 0.5 M HCl Environment by Mature Arecanut Seed Extracts: A Comparative Study by Chemical, Electrochemical and Surface Probe Screening Techniques (N. Raghavendra and J. Ishwara Bhat)

Abstract: The corrosion inhibition behaviour of ethyl acetate extract from mature arecanut seed (EEMAS) and water extract from mature arecanut seed (WEMAS) on aluminium in 0.5 M hydrochloric acid environment was thoroughly investigated by employing gravimetric (weight loss), electrochemical (Tafel plot and AC impedance) and surface probe (SEM and AFM) techniques. From the gravimetric technique, it was observed that, the superior inhibition property was ensured at the concentration of 12 g l-1 of plant extracts. The chemical or physical nature of the film formed by plant extracts (both EEMAS and WEMAS) was further inspected based on kinetic and thermodynamic parameters. According to Tafel plot studies, the corrosion current value decreases appreciably with an increase in the plant product concentration, which is an indication of the reduction in the corrosion rate. An increase in the charge transfer resistance values with the addition of plant extract constituents to the corrosive medium was clearly observed from AC impedance spectroscopy technique. Surface characterisation of target metals by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques as a function of contact time in a corrosive medium (0.5 M HCl) noticeably gives clue about the protective role of plant extracts on the metal (aluminium) surface. The order of protection efficiency obtained from all techniques was found to be WEMAS > EEMAS.

7. Electrospun Poly(methyl Methacrylate)/Polyaniline Blend Nanofibres with Enhanced Toxic Gas Sensing at Room Temperature (Rajashree Anwane and Subhash Kondawar)

Abstract: Continuous progress in the methods of preparation of new materials for sensing of toxic gases has attracted considerable interest due to environmental problems. In the present investigation, poly(methylmethacrylate)/polyaniline (PMMA/PANI) blend nanofibres were prepared by electrospinning and dip-coating polymerisation techniques. The semiconducting behaviour of PMMA/PANI blend was found to be highly sensitive for toxic gases like NH3 and HCl at room temperature suggesting the PMMA/PANI blends as a potential material for effective gas sensing in the environmental monitoring safety systems, chemical industry, automotive industry and medical application areas. Fourier transform infrared (FTIR) spectra clearly show the characteristic peaks indicating the presence of quinoid and benzenoid rings of PANI confirming the formation of PMMA/PANI blend. Clusters of PANI on the uniform fibres of PMMA can be seen in the SEM images. Good thermal stability of PMMA/PANI nanofibres showed highly sensitive with fast response and recovery on exposure to NH3 and HCl gases. The phenomenon of increase in sensitivity with the increase in concentration of NH3 and HCl gases was found to be adsorption dominated indicating that the PMMA/PANI blend nanofibres are more sensitive to the surrounding due to their increased porosity and high aspect ratio. The sensing mechanism of PMMA/PANI blend nanofibres on account of more protonation and de-protonation due to exposing towards HCl and NH3 gases respectively is systematically explained in the present investigation.

8. Gains, Uniformity and Signal Sharing in XY Readouts of the 10 cm × 10 cm Gas Electron Multiplier (GEM) Detector (Anawat Rittirong and Kiadtisak Saenboonruang)

Abstract: The gas electron multiplier (GEM) detector is a promising particle and radiation detector which has been greatly improved from previous gas detectors. In particular, the 10 cm × 10 cm GEM detector is utilised in applications including high-resolution tracking devices in nuclear and particle physics. With its operational and design simplicity, while still maintaining high quality, the GEM detector is suitable for both start-up and advanced research. This article reports simple procedures and results of an investigation of important properties of this detector, using current measurement and signal counting. Results show that gains of the GEM detector increase exponentially as voltages supplied to the detector increase and that the detector reaches full efficiency when the voltages are greater than -4100 V. In terms of signal sharing between X and Y strips of the read-out, the X strips, on the top layer of the read-out, collect larger signals. For the uniformity test, the GEM detector has slightly higher efficiencies at the centre of the detector. These results can be used for future reference and for better understanding of the GEM detector’s characteristics.

9. Investigation of A−X Band System of Astrophysically Significant Molecule BS (Karthikeyan Balasubramanian, Shanmugapriya Ganesan and Rajamanickam Narayanan)

Abstract: It is widely known that molecular signatures in celestial object play a vital role in deriving the physical conditions of the object using spectroscopic technique. The present study therefore focuses on the evaluation of Franck-Condon factors (FCFs) and r-centroids for the A−X band system of Boron mono-sulphide (BS) molecule by a numerical integration method using the suitable potential. With the help of FCFs and r-centroids, the vibrational temperature of the source is estimated and is found to be about 6893 K. The vibrational temperature estimated in the present study reveals that the rotational temperature of the molecule has to be considered for the identification of the chosen band system in the astrophysical spectra. The vibration rotation interaction (VRI) effect for the chosen band system is discussed. It is found that the VRI effect may influence the effective temperature of the source and hence the effect of VRI has to be considered at the time of identifying the BS molecular lines in the spectra of sunspot or any celestial object.

10. Effects of Filler Size on the Mechanical Properties of Polymer-filled Dental Composites: A Review of Recent Developments (Fathie Kundie, Che Husna Azhari, Andanastuti Muchtar and Zainal Arifin Ahmad)

Abstract: Resin composites are widely used in esthetic restorative dentistry. Since their introduction in the mid-1960s, these composites made steady gains in popularity. Their increased use is attributed to their excellent biocompatibility, absence of taste, odour, tissue irritation and toxicity, insolubility in body fluids, easy operation, excellent aesthetic properties, stable colures, optical properties, easily pigmented, low cost and repairability. The composite resins in current use still suffer from several shortcomings such as poor mechanical properties. In order to improve these properties, microparticles have been used as fillers for a long time. However, the inadequate mechanical properties of resin composites remain problematic. Recently, researchers have utilised nanoparticles as dental composite fillers. This article reviews the relevant literature on the mechanical properties of polymer dental composites filled with micro- and nano-scale particles. The effects of particle size on fracture toughness, flexural strength, and hardness were examined with emphasis on other important factors for improvement. The second section focused on the toughening mechanisms of particulate-polymer composites.

Vol. 29, No. 2 (Nov 2018)

1. The Enhancement of Electrical Conductivity and Tensile Properties of Conductive Poly (Vinyl Chloride) / Poly (Ethylene Oxide) / Polyaniline (PAni) Conductive Composite Films: The Effect of Polyaniline Loading and Ethylene Dimethacrylate (EDMA) (Mohammed Izzuddeen Mohd Yazid, Supri A Ghani, AF Osman, and MD Siti Hajar)

Abstract: The effect of ethylene dimethacrylate (EDMA) as surface modifier and polyaniline (PAni) loading on poly (vinyl chloride) (PVC) / poly (ethylene oxide) (PEO) matrix was investigated. PVC/PEO conductive composite films with different PAni loading were fabricated using solution casting technique. The inclusion of EDMA exhibited higher tensile strength, modulus of elasticity and electrical properties for all filler loadings of PVC/PEO/PAni conductive composite films. The scanning electron microscopy (SEM) morphology indicated that the inclusion of EDMA in conductive films provided decent fillers dispersion in the PVC/PEO phases. The structural modifications, if occurred, will be interpreted with the assistance of FTIR spectroscopy.

2. Improvement in Corrosion Resistance of Aluminium alloy by Permanganate-based Conversion Coating (Makanjuola Oki, Adeolu Adesoji Adediran, Bamidele Ogunsemi, Olayinka Agboola Saheed Olayinka and Oyeyemi Ogunsola)

Abstract: This investigation on permanganate based conversion coating describes a chromate-free coating and efforts at reducing the environmental foot prints of metal finishing industries. A golden coloured coating on aluminum specimen was obtained from the permanganate coating (PMC) bath with nominal pH of 7.9. Results from scanning electron microscopy (SEM) examination showed that the conversion coatings are continuous and the surfaces of the specimens treated in the coating bath are composed of irregularly shaped and mud-cracked coating materials. The coatings, as revealed from energy dispersive spectroscopy (EDX) analyses in the SEM are composed essentially of aluminium, oxygen and manganese compounds which are likely to be hydrated. Accelerated corrosion tests in near neutral 3.5% sodium chloride solution and natural exposure tests revealed that the replacement of chromate with permanganate improved paint adhesion and corrosion resistance on aluminium substrates. Furthermore, the results indicated that the corrosion resistance of the permanganate based conversion coating matched those from the traditional chromate coating bath, but for the corrosion resistance after application of a top coat of lacquer, the former was adjudged better than the later.

3. Liquid-Liquid Extraction and Recovery of Pd (II) from Nitric Acid Medium Using Green Diesel as Extractant (B.A. Masrya, M.M. Zeida, A.T. Kassema, H.G. Noweira, E.A. Saadb and J.A. Daouda)

Abstract: A cheap method for the extraction of palladium from HNO3 solution by green Diesel as extractant in kerosene was investigated. Several parameters such as extractant, nitrate, hydrogen ion, nitric acid and metal ion concentration, phase ratio and thermodynamic parameters were studied. The extracted species was deduced using the slope analysis method and IR measurements. The results showed that the extraction efficiency of Pd(II) is 95% with 10% (v/v) Diesel in kerosene , and 97% was recovered from the loaded organic solution using 0.05M thiourea or ammonium thiocyante solutions as stripping agents. The maximum loading capacity of Diesel was found to be 2 × 10-2 moles of Pd (II) per mole extractant. The effect of diluents on the extraction of Pd(II) from nitric acid solution by green Diesel indicated that, under the used experimental conditions, kerosene gave the highest extraction percent compared to cyclohexane, benzene, toluene, chloroform and carbon tetrachloride. Extraction of Pd(II) from different acidic media was also carried out and the extraction percent was found to decrease in the order: H2SO4 > HNO3 >HCl. The possibility of extraction and recovery of palladium from the sulphate leach solution of spent automotive catalyst was explored and a modified process is proposed and evaluated.

4. Effects of Ferric Chloride and Polyaniline Addition on the Properties of Polyethylene Oxide / Polyvinyl Chloride / Polyaniline Conductive Films (Mohammed Izzuddeen Bin Mohd Yazid, Supri Abdul Ghani, Azlin Fazlina Osman and Siti Hajar Binti Mohd Din)

Abstract: Polyethylene oxide (PEO) / Polyvinyl chloride (PVC) blends with 2.5 wt% – 10 wt% polyaniline (PAni) loadings were fabricated with and without the presence of ferric chloride (FeCl3). PEO/PVC/PAni and PEO/PVC/PAni-FeCl3 conductive films were prepared by solution casting method using tetrahydrofuran as the solvent at ambient temperature. The tensile properties, electrical conductivity and structure/morphology of the conductive films were analyzed and discussed in this paper. The results indicated that the tensile strength and elongation at break decreased but the Young’s modulus increased with PAni loading. Meanwhile, PEO/PVC/PAni-FeCl3 conductive films showed lower tensile strength and Young’s modulus but higher elongation at break in comparison with PEO/PVC/PAni conductive films. The agglomeration of PAni at higher loadings was revealed by SEM study. However, this study found that higher loading of PAni increased the electrical conductivity of the films and further improved with the addition of FeCl3. The FTIR study revealed the structure of the films with the effect of PAni as filler and FeCl3 as the oxidizing agent.

5. Preparation of amidoxime adsorbent by radiation induced grafting of acrylonitrile on polyethylene film and its application in Cr(VI) removal (Nazia Rahman, Nirmal Chandra Dafader, Abdur Rahim Miah, Md. Ferdous Alam and Shahnaz Sultana)

Abstract: Pre-irradiation technique was applied to graft acrylonitrile (AN) onto polyethylene film. The graft yield was optimized with respect to radiation dose, monomer concentration and reaction time. H2SO4 was added to the monomer solution to improve the graft yield.  Highest graft yield obtained was 120 % at 70 kGy radiation dose, 60% monomer concentration and 4 h reaction time using H2SO4 as additive. The AN grafted films were modified with hydroxyl amine hydrochloride to prepare amidoxime adsorbent. The prepared adsorbent was characterized by using FTIR, NMR, TGA and DMA. The prepared amidoxime adsorbent showed high affinity towards Cr(VI) adsorption. Adsorption capacity was studied under different conditions: contact time, pH and initial metal ion concentration. The highest adsorption capacity obtained was 200 mg/g of adsorbent after 72 h contact time at pH 1.5 and initial metal ion concentration 200 ppm. Pseudo-first-order and pseudo-second-order equations were used for interpretation of kinetic adsorption data. The equilibrium experimental data of Cr(VI) adsorption were also fitted with Langmuir isotherm model. Desorption and reuse of the adsorbent film was studied.  The adsorbent showed no significant loss of adsorption capacity upon repeated use.

6. A New Treatment to Compute the Track Parameters in PADC Detector using Track Opening Measurement (Saeed Hassan Saeed Al-Nia’emi)

Abstract:  In this paper, a new treatment (or method) has been presented to calculate the parameters of the etched track and its shape development after irradiating the polyallyldiglycol carbonate (PADC) detector CR-39 by alpha particles using the direct measurement of the track opening diameters. The method is based on a concept that the track diameter grow rate VD and the track etch rate VT are not constants with the progressing of the etching process. Some of the equations used in the case of VD to be a constant have been modified as a function of the etching time to be more suitable for the case. Certain boundary conditions have been extracted from previous works that based on the measurement of the track lengths directly from the track’s images, to use them in the equations that were applied to figure out the track parameters in the present work. A CR-39 detector was irradiated with alpha particles of energies of 1.53, 2.35, 3.06, 3.80 and 4.44 MeV under normal incidence using 1Ci 241Am source of 5.485 MeV. The irradiated detectors were etched chemically with an aqueous 6.25 N solution of NaOH at 70oC. The track parameters and the profile development, as well as the V(R’) function, were determined. The results obtained by this method through using the track diameters information were showed a good agreement with previous works that used the direct measurement of the track lengths.

7. Soybean oil bleaching by adsorption onto bentonite/iron oxide nanocomposites (Mohammad Ghorbanpour)

Abstract: The bleaching process of soybean oil using commercial bentonite and Bentonite/iron oxide composites has been studied. X-ray diffraction (XRD), BET surface area measurement and scanning electron microscopy (SEM) were used to characterize the composites generated. SEM results shows that the porosity of bentonite after alkaline ion exchange process can be enhanced by the opening of the bentonite’s flakes. BET shows that the flakes’ structure was more opened and the porosity was increased from 179.58 m2/g for bentonite to 202 m2/g for 3 min ion exchanged sample. Changes in basal reflection in XRD peak validated the presence of iron oxide particles. The experimental results indicate that composite prepared for 1 min show the same efficiency in bleaching crude soybean oil with the bentonite. The greatest reduction in bleaching capacity in soybean oil was achieved using the composite prepared for 3 min. The highest transparency, 1.5-fold in red and 1.25-fold in yellow greater than that of neutralized oil, was obtained with the alkaline ion exchange composite prepared for 3 min. Hence, this process gives a good adsorbent with better bleaching properties than commercial bentonite.

8. Effect of Frequency and Number of Piezoelectric Probes in Sonication-Assisted Exfoliation of Graphite Layers into Graphene Oxide (Aminah Nur Aisyah, Achmad Ainul Fikri, Suhufa Alfarisa, Agus Purwanto, Sumarna, Wipsar Sunu Brams Dwandaru)

Abstract: A self-custom-made ultrasound generator using piezoelectric probes has been constructed to reduce graphite layers via liquid-phase exfoliation into graphene oxide (GO) material. The ultrasound frequency and the number of piezoelectric probes are varied with values of 20 kHz, 30 kHz, and 35 kHz, and 1 probe, 2 probes, and 3 probes, respectively. The solutions obtained from the sonication process show a temperature increase of 1 or 2 oC compared to room temperature. Color changes of the solution before sonication, after sonication, and after being left overnight are also exhibited; that is from dark, dark blue, to grayish blue, respectively. The solutions are then characterized using UV-Vis spectrophotometer and scanning electron microscope (SEM). The UV-Vis results show the presence of GO material at an absorbance peak of 270 nm. Increasing the frequency and number of the probes decreases the absorbance peaks of the solutions. The best GO sample solution is obtained for an ultrasound frequency of 35 kHz and using 3 piezoelectric probes. Images from SEM show rod-like carbon materials stacked on top of each other in the form of flower-like structures. The widths of these rod-like materials vary from 1 to 2 microns; whereas the thicknesses of these materials are around 300 nm to 1.5 microns.

9. Study of ethanol vapor sensing behavior by Polypyrrole-Multiwall carbon nanotubes nanocomposites (Sanjay G. Bachhav, Dilip R. Patil)

Abstract: Polypyrrole-multiwall carbon nanotubes (PPy/MWCNT) nanocomposites were synthesized by in-situ chemical oxidative polymerization method. The MWCNTs were functionalized prior to the formation of nanocomposites. These nanocomposites were characterized by Field Emission Scanning Electron microscopy (FE-SEM), X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and thermogravimetric analysis (TGA) to study the effect of incorporation of functionalized MWCNT in polypyrrole matrix. The results showed the successful formation of PPy/MWCNT nanocomposite and there is significant interaction between PPy and MWCNTs. The response of the prepared PPy/MWCNT nanocomposites sensors was studied in the form of sensitivity towards ethanol vapors. Results showed that the response increases with ethanol concentration and it is also affected by the MWCNT content in PPy matrix.

10. Catalytic Hydrogenation of Hydrocarbons for Gasoline Production (M.D. Garba and A. Galadima)

Abstract: The persistent growth in the global population has also accounted for the continuous increase in the used of gasoline-based automobile engines. Although the application of gasoline additives such as tetraethyl lead (TEL), oxygenates and metal carbonyls like methyl cyclopentadienyl manganese tricarbonyl (MCT) have been considered suitable for gasoline quality upgrading, the numerous challenges that include environmental pollution and destruction to catalytic converters attributed to search for better valorisation options. The hydrogenation of hydrocarbon fractions from petroleum refining is a forefront issue recently adopted by the refineries worldwide. The process involved the incorporation of suitable catalytic systems under hydrogen atmosphere to upgrade hydrocarbons into similar derivatives of better gasoline properties. The paper carefully tailored a series of recently published literature on the various aspect of the hydrogen process with emphasis to catalyst design and testing, mechanisms, industrial perspective and challenges. Areas for further investigations were also discussed.