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Interval forecasting provides decision-makers with a range of possible future values, along with associated probabilities, which allows for a more informed decision-making process. Although GARCH models under different distributional assumptions are commonly compared for their volatility forecasting performance, their performance in interval forecasting is rarely discussed. This study aims to fill this gap by comparing the interval forecasting accuracy of GARCH models under symmetric and asymmetric distributions. SGARCH, EGARCH, and GJR-GARCH models under normal, student-t, GED distributions, and their skewed extensions are applied for one-day-ahead rolling interval forecasting on five major European and American stock indices: S&P 500, FTSE 100, CAC 40, DAX 30 and AEX. The average Winkler score (AWS) is used to measure the accuracy of interval forecasting. The conclusions of this study can be summarised as follows: In pairwise comparisons, the GARCH models under asymmetric distributional assumptions have better interval forecasting accuracy than the GARCH models under symmetric distributional assumptions. In comparisons among GARCH-type models, GJR-GARCH has better interval forecasting accuracy than SGARCH and EGARCH, while SGARCH and EGARCH exhibit similar interval forecasting performance.

Interval forecasting provides decision-makers with a range of possible future values, along with associated probabilities, which allows for a more informed decision-making process. Although GARCH models under different distributional assumptions are commonly compared for their volatility forecasting performance, their performance in interval forecasting is rarely discussed. This study aims to fill this gap by comparing the interval forecasting accuracy of GARCH models under symmetric and asymmetric distributions. SGARCH, EGARCH, and GJR-GARCH models under normal, student-t, GED distributions, and their skewed extensions are applied for one-day-ahead rolling interval forecasting on five major European and American stock indices: S&P 500, FTSE 100, CAC 40, DAX 30 and AEX. The average Winkler score (AWS) is used to measure the accuracy of interval forecasting. The conclusions of this study can be summarised as follows: In pairwise comparisons, the GARCH models under asymmetric distributional assumptions have better interval forecasting accuracy than the GARCH models under symmetric distributional assumptions. In comparisons among GARCH-type models, GJR-GARCH has better interval forecasting accuracy than SGARCH and EGARCH, while SGARCH and EGARCH exhibit similar interval forecasting performance.

In this paper, we investigate a two-hop simultaneous wireless information and power transfer (SWIPT) amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay communication system with an energy-limited relay node. The relay node harvests energy based on the radio-frequency (RF) signal transmitted from the source node through the time-switching (TS) protocol and fully uses the harvested energy to precode and forward the information to the destination node. The non-linear energy harvesting models are considered at the relay node. With the consideration of the channel estimation error, the joint optimization of the TS factor, source and relay precoding matrices is proposed with robustness against the channel state information (CSI) mismatch to maximize the mutual information (MI) between the source and destination nodes. The optimal structure for the source and relay precoding matrices is derived to simplify the transceiver optimization problem. Numerical simulations show that the system performance provided by the proposed algorithms with robustness is better than the non-robust algorithm.

Two-way communication links are required in power-line communication (PLC) as a smart grid enabler. As PLC systems suffer from harsh power-line channels, it is beneficial to provide spatial diversity to improve the system performance. Using a two-way multicarrier relay configuration, this paper investigates the power optimization of a relay-assisted PLC system with the consideration of the quality of service (QoS) constraints. Since the QoS constrained power allocation problem is highly non-convex, an alternating optimization (AO) algorithm is proposed to decompose the optimization problem into subproblems. Simulation results show the proposed system is able to reduce the total power required by the system for about 40% compared to the conventional bidirectional direct transmission (BDT) system under the same QoS requirement. Further, the proposed system consumes less power compared to the relayassisted two-way information exchange (R2WX) system.

© 2018 The Society for Applied Microbiology Aims: To investigate the biofilm inhibitory activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms. Methods and Results: The pulp of red pitahaya and the leaves of red spinach were extracted using methanol followed by subfractionation to obtain betacyanin fraction. The anti-biofilm activity was examined using broth microdilution assay on polystyrene surfaces and expressed as minimum biofilm inhibitory concentration (MBIC). The betacyanin fraction from red spinach showed better anti-biofilm activity (MBIC: 0·313–1·25 mg ml-1) against five Staph. aureus strains while the betacyanin fraction from red pitahaya showed better anti-biofilm activity (MBIC: 0·313–0·625 mg ml-1) against four P. aeruginosa strains. Both betacyanin fraction significantly reduced hydrophobicity of Staph. aureus and P. aeruginosa strains. Numbers of Staph. aureus and P. aeruginosa attached to polystyrene were also reduced without affecting their cell viability. Conclusion: Betacyanins can act as anti-biofilm agents against the initial step of biofilm formation, particularly on a hydrophobic surface like polystyrene. Significance and Impact of the Study: This study is the first to investigate the use of betacyanin as a biofilm inhibitory agent. Betacyanin could potentially be used to reduce the risk of biofilm-associated infections.

© 2018 Elsevier Ltd Red pitahaya fruit is rich in purplish-red color water-soluble betacyanins. The effect of refrigerated storage at 4 °C on the betacyanin composition of red pitahaya was monitored each day, for one week, using HPLC. The betacyanin content of red pitahaya had increased by 57.2% after storage for six days at 4 °C. From day 2 to day 7, the phyllocactin content decreased from 45.4 ± 1.5% to 38.3 ± 3.1%, whereas the betanin content increased from 37.9 ± 1.6% to 42.7 ± 1.5%. Antimicrobial activity was determined using the broth microdilution assay and expressed as minimum inhibitory concentration (MIC). As compared to the freshly harvested fruits (MIC values: 50,000– > 50,000 µg mL -1 ), fruits that were stored for six days at 4 °C demonstrated better antimicrobial activity (MIC values: 3130–6250 µg mL -1 ) against 10 pathogenic Gram-positive and 6 Gram-negative bacteria. Betacyanin rich extract was also examined against normal human cell lines (HEK-293 and THP-1) and found to be not cytotoxic at the levels of 0.39–3.13 mg mL -1 . In summary, refrigerated storage for 6 days increased the betacyanin content, changed the betacyanin composition in red pitahaya and contributed to higher antimicrobial activity.

© 2017 Elsevier Ltd The present study investigated the effects of pH (pH 3, 4, 5 and 6) treatment and refrigerated storage at 4 °C on the stability of colourant preparations from red pitahaya and compared to a commercial colourant preparations from red beet, E-162. The potential of using colourant preparations from red pitahaya in yoghurt and compared to E-162 was also investigated. Immediately after pH treatment, the highest percentage of reduction of betacyanin was observed at pH 3. The loss of betacyanin content in yoghurts containing colourant preparations from red pitahaya and E-162 over 14-days of refrigerated storage was 1.0± 0% and 1.6± 0.1%, respectively. Syneresis in yoghurt containing colourant preparations from red pitahaya and E-162 were lower than that of plain yoghurt. The addition of betacyanins from red pitahaya or E-162 increased the free radical scavenging activity in yoghurts. The total microbial counts of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus in yoghurts containing colourant preparations from red pitahaya and E-162 were in the 10 8 –10 9 CFU/mL range. The colour acceptability of yoghurt containing colourant preparation from red pitahaya was similar with E-162 and a commercial strawberry flavoured yoghurt suggesting its potential application as a natural functional colourant.

The effects of temperature (30, 50, 85 and 100 °C) treatment and 10 weeks of refrigerated storage (4 °C) on the betacyanin content and colour stability of betacyanins from red pitahaya (Hylocereus polyrhizus) were investigated and compared to red beet (Beta vulgaris; E-162) which was used as a control. Temperature treatment at 50 and 85 °C caused a greater reduction in betacyanin content (BC) in E-162 compared to red pitahaya by inducing changes in betacyanin profile. The 10 weeks of refrigerated storage at 4 °C induced colour changes in betacyanins from red pitahaya and E-162. In milk, betacyanins from red pitahaya presented a lower loss of BC and total colour changes (ΔE*) compared to E-162. The microbial onset in milk containing betacyanins from red pitahaya and E-162 was delayed up to day 5 of refrigerated storage at 4 °C compared to day 3 in plain milk. Milk containing betacyanins from red pitahaya showed better colour acceptability (3.89 ± 1.89) compared to E-162 (6.10 ± 1.71). Hence, betacyanins from red pitahaya may be a potential natural functional colourant to simulate strawberry colour in milk.

Betacyanins are reddish to violet pigments that can be found in red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius). This study investigated the impact of sub-fractionation (solvent partitioning) on betacyanin content in both plants. Characterization of betacyanins and evaluation of their antimicrobial activities were also carried out. Betanin was found in both plants. In addition, isobetanin, phyllocactin and hylocerenin were found in red pitahaya whereas amaranthine and decarboxy-amaranthine were found in red spinach. Sub-fractionated red pitahaya and red spinach had 23.5 and 121.5 % more betacyanin content, respectively, than those without sub-fractionation. Sub-fractionation increased the betanin and decarboxy-amaranthine content in red pitahaya and red spinach, respectively. The betacyanin fraction from red spinach (minimum inhibitory concentration [MIC] values: 0.78–3.13 mg/mL) demonstrated a better antimicrobial activity profile than that of red pitahaya (MIC values: 3.13–6.25 mg/mL) against nine Gram-positive bacterial strains. Similarly, the red spinach fraction (MIC values: 1.56–3.13 mg/mL) was more active than the red pitahaya fraction (MIC values: 3.13–6.25 mg/mL) against five Gram-negative bacterial strains. This could be because of a higher amount of betacyanin, particularly amaranthine in the red spinach.

Betalains are plant derived natural pigments that are presently gaining popularity for use as natural colorants in the food industry. The growing interest of consumers in the aesthetic, nutritional and safety aspects of food has increased the demand for natural pigments such as betalains to be used as alternative colorants in food products. Although betalains from red beetroot are one of the most widely used food colorant, betalains are not as well studied as compared to other natural pigments such as anthocyanins, carotenoids or chlorophylls. This paper reviews the pharmacological properties, such as antioxidant, anti-cancer, anti-lipidemic and antimicrobial activity of betalains derived from sources such as red beetroot, amaranth, prickly pear and red pitahaya, for potential application as functional foods.

Pacific white shrimps (Litopenaeus vannamei) are an important shrimp aquaculture species worldwide. To quantify the quality and shelf life of untreated shrimp is imperative prior to the application of preservative treatments. In this paper, the quality and shelf life of Pacific white shrimp freshly harvested from three different farms and stored on ice for up to 12 days was investigated. The titratable acidity (TA) of shrimp specimens exhibited significant decreases (P < 0.05) whereas the metric chroma (C), total colour difference (TCD), aerobic plate count (APC), trimethylamine (TMA-N) and total volatile basic – nitrogen (TVB-N), peroxide value (PV) and p-anisidine value (AnV) exhibited significant increases during iced storage (P < 0.05). The TMA-N and TVB-N were significantly correlated whereas temporal TMA-N/TVB-N ratio increased considerably (P < 0.05). While the PV and AnV significantly correlated (P < 0.05), the temporal PV/AnV ratio depicted how primary and secondary lipid oxidation of Pacific white shrimp could relate during iced storage of 12 days. The shelf life of ice stored Pacific white shrimps was determined to be 8 days. The information gained by this study could serve as baseline for preservative treatments applied to fresh shrimps.

Plastics see very widespread use in modern society. The properties of many plastics can be modified relatively easily to fit a wide variety of applications. However, the disposal of waste plastics presents a significant environmental challenge. Recently, there has been considerable interest into tertiary recycling of waste plastics to produce liquid fuel. This project focuses on the formation of aromatic hydrocarbons during thermal pyrolysis of plastics. Several reactor configurations have been suggested for the pyrolysis of plastics. The reactor configuration used in this study consists of a stirrer tank reactor coupled with a reflux column and a condenser.

Solid state fermentation (SSF) which involves the growth of microorganism on moist solid substrates in the absence of free flowing water, has gained renewed attention over submerged fermentation for specific applications. During the SSF process in fermenter, there are three main engineering problems encountered such as the removal of metabolic heat from the substrate, diffusion of O2 and moisture through the substrate, and heterogeneity of the substrate and inoculum. A fluidized bed fermenter in which the particles move independently like a fluid was proposed to conduct the study. Throughout the study, rapid heat transfer from PKC to air was experimentally observed within the first 150 s with a temperature drop of 30 °C. This indicated that the excellent heat transfer between palm kernel cake and air allows solid state fermentation of PKC without accumulation of metabolic heat in the fermenter. Apart from heat removal, water adsorption study on PKC from air to bed was carried out. It showed that the increase of adsorbed water in PKC was proportional to air relative humidity and inversely proportional to superficial air velocity. The maximum moisture content adsorbed by PKC under fluidization conditions was around 10% (on dry basis). Finally, mathematical models for heat and mass transfer were proposed which can predict the experimental data quite satisfactorily.

Solid state fermentation (SSF) which involves the growth of microorganism on moist solid substrates in the absence of free flowing water, has gained renewed attention over submerged fermentation for specific applications. During the SSF process in fermenter, there are three main engineering problems encountered such as the removal of metabolic heat from the substrate, diffusion of O2 and moisture through the substrate, and heterogeneity of the substrate and inoculum. A fluidized bed fermenter in which the particles move independently like a fluid was proposed to conduct the study. Throughout the study, rapid heat transfer from PKC to air was experimentally observed within the first 150 s with a temperature drop of 30 °C. This indicated that the excellent heat transfer between palm kernel cake and air allows solid state fermentation of PKC without accumulation of metabolic heat in the fermenter. Apart from heat removal, water adsorption study on PKC from air to bed was carried out. It showed that the increase of adsorbed water in PKC was proportional to air relative humidity and inversely proportional to superficial air velocity. The maximum moisture content adsorbed by PKC under fluidization conditions was around 10% (on dry basis). Finally, mathematical models for heat and mass transfer were proposed which can predict the experimental data quite satisfactorily.

Solid state fermentation (SSF) which involves the growth of microorganism on moist solid substrates in the absence of free flowing water, has gained renewed attention over submerged fermentation for specific applications. During the SSF process in fermenter, there are three main engineering problems encountered such as the removal of metabolic heat from the substrate, diffusion of O2 and moisture through the substrate, and heterogeneity of the substrate and inoculum. A fluidized bed fermenter in which the particles move independently like a fluid was proposed to conduct the study. Throughout the study, rapid heat transfer from PKC to air was experimentally observed within the first 150 s with a temperature drop of 30 °C. This indicated that the excellent heat transfer between palm kernel cake and air allows solid state fermentation of PKC without accumulation of metabolic heat in the fermenter. Apart from heat removal, water adsorption study on PKC from air to bed was carried out. It showed that the increase of adsorbed water in PKC was proportional to air relative humidity and inversely proportional to superficial air velocity. The maximum moisture content adsorbed by PKC under fluidization conditions was around 10% (on dry basis). Finally, mathematical models for heat and mass transfer were proposed which can predict the experimental data quite satisfactorily.

Solid state fermentation (SSF) which involves the growth of microorganism on moist solid substrates in the absence of free flowing water, has gained renewed attention over submerged fermentation for specific applications. During the SSF process in fermenter, there are three main engineering problems encountered such as the removal of metabolic heat from the substrate, diffusion of O2 and moisture through the substrate, and heterogeneity of the substrate and inoculum. A fluidized bed fermenter in which the particles move independently like a fluid was proposed to conduct the study. Throughout the study, rapid heat transfer from PKC to air was experimentally observed within the first 150 s with a temperature drop of 30 °C. This indicated that the excellent heat transfer between palm kernel cake and air allows solid state fermentation of PKC without accumulation of metabolic heat in the fermenter. Apart from heat removal, water adsorption study on PKC from air to bed was carried out. It showed that the increase of adsorbed water in PKC was proportional to air relative humidity and inversely proportional to superficial air velocity. The maximum moisture content adsorbed by PKC under fluidization conditions was around 10% (on dry basis). Finally, mathematical models for heat and mass transfer were proposed which can predict the experimental data quite satisfactorily.

Solid state fermentation (SSF) which involves the growth of microorganism on moist solid substrates in the absence of free flowing water, has gained renewed attention over submerged fermentation for specific applications. During the SSF process in fermenter, there are three main engineering problems encountered such as the removal of metabolic heat from the substrate, diffusion of O2 and moisture through the substrate, and heterogeneity of the substrate and inoculum. A fluidized bed fermenter in which the particles move independently like a fluid was proposed to conduct the study. Throughout the study, rapid heat transfer from PKC to air was experimentally observed within the first 150 s with a temperature drop of 30 °C. This indicated that the excellent heat transfer between palm kernel cake and air allows solid state fermentation of PKC without accumulation of metabolic heat in the fermenter. Apart from heat removal, water adsorption study on PKC from air to bed was carried out. It showed that the increase of adsorbed water in PKC was proportional to air relative humidity and inversely proportional to superficial air velocity. The maximum moisture content adsorbed by PKC under fluidization conditions was around 10% (on dry basis). Finally, mathematical models for heat and mass transfer were proposed which can predict the experimental data quite satisfactorily.

This paper looks at an international collaborative project in teacher education between Malaysian Institutes of teacher training and an Australian university from the perspectives of four of the participants. Two of the stories are from participants who are co-ordinating aspects of the collaboration, and two stories come from participants who were involved closely in the curriculum and teaching aspects of the program. These personal stories reveal that international collaborative projects are indeed like the durian: there are both good and bad aspects. Our differing roles in the program allow us to provide rich insights into such an international collaboration that we believe will be of benefit to others attempting similar projects.