Malaysian Journal of Science

EFFECTS OF VARIOUS LIGHT INTENSITIES ON PHYCOCYANIN COMPOSITION OF CYANOBACTERIUM LIMNOSPIRA FUSIFORMIS (VORONICHIN) NOWICKA-KRAWCZYK, MÜHLSTEINOVÁ & HAUER

2022-04-05T11:54:39+08:00

Phycocyanin denotes a photosynthetic pigment discovered in Rhodophyta and cyanobacteria, which has been used in medical, industrial, and agricultural applications. In general, phycocyanin production by cyanobacteria depends on many environmental conditions, mainly light during the cultivation period. The goal of this research was to see how various light intensities of 47, 52, as well as 60 µmol m^-2 s^-1, affected the Phycocyanin production of cyanobacterium Limnospira fusiformis cultured in Zarrouk medium with a maximum temperature of 28°C. The outcomes revealed that with mild light intensity (52 µmol m^-2 s^-1), increased phycocyanin production of 11.94 ng/mg took place. With regard to greater light intensity (60 µmol m^-2 s^-1), the lesser phycocyanin production of 0.57 ng/mg took place. These results give a good impression that moderate lighting increases phycocyanin production, but high light intensity inhibits it. The statistical analysis results also showed that there are significant differences between the light intensities used in the study at a level of p<0.05. Therefore, this study concluded that phycocyanin was affected by light intensity. Light regime optimization gives a good yield of this pigment. In this study, high phycocyanin production by cyanobacterium Limnospira fusiformis occurred in mild light intensity (52 µmol m^-2 s^-1).

LARVICIDAL ACTIVITY OF THE SYNTHESISED LIGNANS, NEOLIGNANS, AND COUMARIN AGAINST Crocidolimia binotalis 2nd INSTAR LARVAE

2022-09-23T14:27:43+08:00

Five compounds comprising 8-O-4’-neolignan (7), two arylnaphthalene lignans (5, 8), aryldihydrobenzofuran neolignan (4), and lignan (6) were synthesised by enzymatic coupling reaction using horseradish peroxidase (HRP) between vanillin (1) with methyl ferulate (2) or methyl sinapate (3). All of these compounds, as well as previously synthesised palladium-catalysed coupling products of neolignan (9), 8-O-4'-neolignan (10), arylcoumarin (11), and lignan (12), were examined for larvicidal activity against Crocidolomia binotalis 2^nd instar larvae. It revealed that seven out of nine synthesised compounds had a mortality rate of more than 90% after 24 hours of exposure. Neolignan (10) and lignan (6) demonstrated the strongest larvicidal activity with LD₅₀= 2.218 mg/L and LD₅₀= 1.678 mg/L, respectively compared to the standard azadirachtin (LD₅₀=2.818 mg/L). The results showed that the synthesised compounds have a high potential for use in the control of C. binotalis larvae and could be used in the development of new and more effective compounds as larvicides.

A TWO-WAREHOUSE INVENTORY MODEL WITH REWORK PROCESS AND TIME-VARYING DEMAND

2022-02-21T13:08:11+08:00

A two-warehouse inventory model with deteriorating items and rework process with time varying demand rate is presented. The Last-In-First-Out (LIFO) and First-In-First-Out (FIFO) policies are considered with the assumption that the holding cost is higher in the rented warehouse (RW) compared to the owned warehouse (OW). The aim of the proposed model is to determine the optimum values of time in a production cycle that will minimise the total relevant cost, TRC*. We have utilised Microsoft Excel Solver as a solution tool, in which the generalised reduced gradient (GRG Nonlinear) method has been chosen as the solving method. The result is further verified using the built-in function in the Mathematica software. We observed that given same changes are made to the parameters in both the LIFO and FIFO systems, a lower total relevant cost, TRC* is obtained in the LIFO system. This shall mean that the LIFO system is less expensive than the FIFO system, provided that the holding cost in RW is higher than the holding cost in OW. The flow of inventory in the LIFO system suggests that items stored last in the owned warehouse will be dispatched first. This is an important factor for manufacturers in ensuring that items are distributed at optimal freshness.

TWO-SAMPLE TEST FOR RANDOMLY CENSORED DATA

2022-02-15T22:14:47+08:00

In this paper, a nonparametric test has been proposed for the two-sample scale problem, when sample observations are randomly right censored. The proposed test is based on the extremes of observations as an extension of commonly used Gehan’s test for two-sample problem. Critical values are obtained through simulation for various lifetime distributions at different sample sizes. Power performance for the proposed test is studied considering various distributions. On comparing with the Gehan’s test, it is found that the proposed test has more statistical power and efficiency for some special cases. An illustration with real-life data set is also provided.

MODELLING THE MULTITEAM PREY–PREDATOR DYNAMICS USING THE DELAY DIFFERENTIAL EQUATION

2022-06-07T10:42:15+08:00

In nature, many species form teams and move in herds from one place to another. This helps them in reducing the risk of predation. Time delay caused by the age structure, maturation period, and feeding time is a major factor in real-time prey–predator dynamics that result in periodic solutions and the bifurcation phenomenon. This study analysed the behaviour of teamed-up prey populations against predation by using a mathematical model. The following variables were considered: the prey population P_r1, the prey population P_r2, and the predator population P_r3. The interior equilibrium point was calculated. A local satiability analysis was performed to ensure a feasible interior equilibrium. The effect of the delay parameter on the dynamics was examined. A Hopf bifurcation was noted when the delay parameter crossed the critical value. Direction analysis was performed using the centre manifold theorem. The graphs of analytical results were plotted using MATLAB.

AN INTEGRAL TRANSFORM TOGETHER WITH TAYLOR SERIES AND DECOMPOSITION METHOD FOR THE SOLUTION OF NONLINEAR BOUNDARY VALUE PROBLEMS OF HIGHER ORDER

2022-07-13T21:17:27+08:00

This work aims to determine the approximate solutions of nonlinear boundary value problems of higher order obtained through the Aboodh Transform Series Decomposition Method (ATSDM), a method designed to find the integral and the inverse transform of the problems, expand the exponential function, and simultaneously decompose the nonlinear terms. The results obtained demonstrate that ATSDM is an excellent and trusted approximate method that can be employed to obtain accurate results for any problem similar to the one presented in this work.

SMART FARMING USING A SOLAR POWERED AQUAPONICS SYSTEM FOR A SUSTAINABLE FOOD PRODUCTION

2022-06-23T15:39:22+08:00

This paper discusses the prospect of utilization of solar energy for aquaponics operation. Aquaponic is a platform for farmers to simultaneously grow fish and plants in a same unit. It is sustainable and produces little waste. The need of pumps for continuous water recirculation and air supply within the system could be a hindrance in the aquaponics operation especially if the unit is nowhere near any power outlet. It is indeed a visible solution as Malaysia located at equator and receives average sunlight ~9 hours a day throughout the year with solar intensity as high as 1800-1900 kWh/m². The work presents detail equipment for establishment of suitable solar PV system for aquaponics operation and reviews utilities of aquaponics platform that can be supported using solar energy. Possible integration of Internet-of-Things (IoT) for remote monitoring of such solar operated aquaponics unit is also discussed. Analysis showed that even when operated with full energy supply for only 12 hours, the yield and growth rates of the crop and fish grown in the system powered remains unaffected. This signified the potential for the use of solar energy as alternative energy for operation of the aquaponics unit. The main advantage perhaps is the realization of aquaponics setup in remote area where electricity is not accessible. Installation cost may be relatively high (100W PV system could cost nearly RM 600 for installation) but for a long run, it is highly beneficial as utility cost and cost for installing the national grid can be significantly reduced. Summarizing, the project introduced the concept of smart farming via aquaponics for a sustainable production of crop and fish using a renewable and clean solar energy for its operation.

THE HEALTH BENEFITS OF FERMENTED FOOD: A NARRATIVE REVIEW

2022-02-11T10:00:54+08:00

Fermented foods are consumed in many parts of the world since ancient times and they include dairy products, meat, fruits, vegetables, and alcoholic beverages. These foods have been documented to be beneficial to human health due to the microbial content, which mainly consists of probiotics of various bacterial and fungal species. Fermented food probiotics can modulate gastrointestinal health, thereby affecting other bodily systems such as the immune system and brain functions. The microbial and nutritional content of fermented foods may also contribute to reducing cardiovascular risks and improving metabolic syndrome parameters. Fermented foods have antimicrobial properties that can aid in suppressing the growth of pathogenic microbes. In addition, fermented foods may impart beneficial effects to the nervous system, which include improvement of cognitive function and a decrease in the symptoms of depression, anxiety, and stress. Literature relating to the benefit of fermented foods on different aspects of human health is sparse which poses significant limitations on understanding the relationship between fermenting foods and human health. This paper describes different types of fermented foods containing the relevant micro-organisms associated with the improvement of several health conditions.

STUDY OF FECAL GLUCOCORTICOID METABOLITE IN BEARS: A REVIEW

2022-03-21T11:01:10+08:00

Fecal glucocorticoid metabolite (FGM) analysis is a non-invasive method to monitor animals' welfare in captivity and wild environments. Glucocorticoid also known as cortisol is a hormone that indicates the level of stress in animals and humans. This paper reviews the use of FGM analysis on bears and the methodologies used to study this hormone in every species of bear. The review method used was descriptive review. The bears that were included in this review are the brown bear (Ursus arctos), Polar bear (Ursus maritimus), Asiatic black bear (Ursus thibetanus), American black bear (Ursus americanus), Malayan sun bear (Helarctos malayanus), sloth bear (Melursus ursinus), Andean spectacled bear (Tremactos ornatus), and giant panda (Ailuropodia melanoleuca). Studies of FGM on polar bears showed that zoo-to-zoo transportation could cause an increase in FGM level during transportation and FGM is not suitable to be used to differentiate between pseudo-pregnancy and true pregnancy. In Malayan sun bear, FGM level is high in female bears that show agonistic behavior and is associated with low progesterone levels. In addition, studies on Malayan sun bear show that not only FGM can be analyzed from fecal samples, but also the reproductive hormones of estrogen and progesterone. In Asiatic black bears, FGM is higher in bears that live in a bile farm than forage outside the forest reserve. High parasite load in giant pandas is associated with a high level of FGM since parasite infection is considered a stressor that can elicit a stress response. Also both male and female panda have high FGM during the breeding season to increase metabolism to generate energy required for reproductive activities. The Alopecia syndrome in Andean spectacled bear has no significant relation to FGM level. Brown bears with several types of food in their diet have lower FGM than those with only one type of food. There is no specific study of FGM that focused on sloth bear and American black bear, but there were several studies on glucocorticoid in black bears that are not extracted from fecal samples. FGM can be analyzed using both enzyme-immunoassay (EIA) and radioimmunoassay (RIA) but, EIA is preferable due to safety reasons.

ANTHOCYANINS: A HUE FOR HISTOLOGY - SYSTEMATIC REVIEW

2022-03-13T19:25:59+08:00

Background: Many histological stains cause health hazards to technicians, pathologists, and researchers. The hazard-free and eco-friendly natural anthocyanins have the potential to be a new source for histological stains. This study aims to systematically review the use of plant products containing anthocyanin for histopathological diagnosis. Methods: A comprehensive literature search was done using suitable keywords on Wiley, PubMed, Scopus, Google Scholar, and Web of Science databases. A total of 30 articles were selected for systematic review, where data obtained from the studies were tabulated. Results: About 90% of the reviewed studies have proven that anthocyanin-containing plant products may be used as natural stains. Out of the 30 studies, 49% involved the use of Hibiscus extract, 11% utilised mulberry extract, 9% utilised pomegranate, another 9% involved rose, and the remaining ones utilised black plum, black rice, butterfly pea, the flame of woods, onion skin, and red poppy extracts. Almost 40% of the studies concluded that aqueous extracts are superior to alcohol ones, and 46% used either iron or alum as mordant. Conclusion: Natural stains containing anthocyanin could be a better alternative to synthetic histological stains. Further extensive studies should be conducted to observe the use of these stains in pathological diagnosis.