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Rice blast (caused by Pyricularia oryzae) is the most devastative disease threatening sustainability rice production. The role of silicon as a foliar application in biochemical defence involvement towards P. oryzae infection in aerobic rice remains unclear. The goal of this study was to explore the effectiveness of silicon (Si) as a foliar spray in triggering phytoalexin synthesis to increase resistance against P. oryzae infection on two aerobic rice cultivars MR219-4 (partially resistant to rice blast) and MARDI Aerob 1 (resistant). Three Si sources: calcium silicate, silica oxide and sodium metasilicate were tested at 3, 6, and 9 mg/L against P. oryzae infection. Foliar application of calcium silicate at 9 mg/L significantly reduced rice blast disease severity to 0.11% (MARDI Aerob 1) and 3.30% (MR219-4). In vitro screenings of phytoalexins (sakuranetin and momilactone A) against P. oryzae revealed that sakuranetin is more prominent to inhibit P. oryzae in both solid and liquid media. The expression of sakuranetin was further quantified from Si-mediated rice seedlings after challenge inoculated with P. oryzae. High-Performance Liquid Chromatography (HPLC) revealed that sakuranetin in both Si-mediated rice seedlings inoculated with P. oryzae significantly increased at 2nd DAI with 0.13 mg/mL in MARDI Aerob 1 and 0.48 mg/mL in MR219-4 compared with control (without Si foliar application). These results emphasized calcium silicate as foliar spray augmented resistance to P. oryzae infection by prolonging sakuranetin accumulation as one of the mechanisms that strengthening the rice plant health besides physiological barrier mechanism in the aerobic rice.

Syzygium myrtifolium Walp. (Syzygium campanulatum Korth), Myrtaceae, is locally known as “Kelat paya” in Malaysia. Traditionally, it is used as a remedy for stomach pain. The goal of the present study was to investigate the toxicological potential as well as the antidiarrhoeal and antispasmodic activities of betulinic acid, dimethyl cardamonin and standardized non-formulated and nano-formulated ethanol and supercritical fluid extracts prepared from leaves of S. myrtifolium. The standardized extracts did not produce in vivo toxicity. Both the compounds and standardized extracts showed dose-dependent antidiarrhoeal activity by examining changes in the percentage of liquid stools and percentage of defecation frequency. Dimethyl cardamonin and standardized extracts showed antispasmodic activity on the isolated ileum of guinea pigs. Compared with hyoscine-N-butylbromide, dimethyl cardamonin and standardized extracts produced significant, potent antagonizing activity in ileum contractions induced with acetylcholine. Furthermore, the antagonistic potential of S. myrtifolium active markers against muscarinic type M2 and M3 receptors was investigated by molecular docking.

Good indoor air quality (IAQ) is essential to ensure students’ and teachers’ improved performance and productivity. This study aimed to investigate particulate matter (PM) concentration with different sizes in a classroom during haze episode and to evaluate the health effect of air pollution during haze to the school student in Malaysia. The particulate matter concentration with aerodynamic diameter size less than 10 µm (PM10) was collected for 8 h using a low volume air sampler (LVS) equipped with quartz filter paper. The trace metals element (Pb, Cd, Co, Ni, Cr, Mn, As and Cu) in PM10 was analysed using inductively coupled plasma mass spectrometry (ICP-MS). Simultaneously, PM concentration in real time at differences sizes (PM10, PM2.5 and PM1) was also collected using Grimm aerosol spectrometer with 1-min interval. A questionnaire survey on school children’s health condition and the lung function test using spirometry were also performed. The results show that there was no significant difference in PM10 concentration during haze (95 ± 25 μg m−3). The dominant trace metal concentrations in PM10 were Mn and Cr both during haze. The mean concentrations of continuous monitoring of PM10, PM2.5 and PM1 during haze event were 85 ± 14 μg m−3, 68 ± 16 μg m−3 and 61 ± 16 μg m−3. The mean forced expiratory volume in the first second (FEV1) and the mean forced vital capacity (FVC) value during haze were 97.7% and 91.8%. The health risk assessment of school children on trace metals in PM10 via inhalation was higher than the acceptable value with a total hazard quotient (HQ) more than 1.0 for both hazes. For carcinogenic elements, the excess lifetime cancer risk (ELCR) was higher than the acceptable limit for haze event with a value of 3.4XE-05. This study found that the impact of haze pollution on indoor PM10 concentration was relatively low; however, there was still a high exposure of school children to the carcinogenic and non-carcinogenic elements during haze event.

This study investigates the recent extreme temperature trends across 19 stations in the Klang Valley, Malaysia, over the period 2006–16. Fourteen extreme index trends were analyzed using the Mann-Kendall non-parametric test, with Sen’s slope as a magnitude estimator. Generally, the annual daily mean temperature, daily mean maximum temperature, and daily mean minimum temperature in the Klang Valley increased significantly, by 0.07°C yr−1, 0.07°C yr−1 and 0.08°C yr−1, respectively. For the warm temperature indices, the results indicated a significant upward trend for the annual maximum of maximum temperature, by 0.09°C yr−1, and the annual maximum of minimum temperature, by 0.11°C yr−1. The results for the total number of warm days and warm nights showed significant increasing trends of 5.02 d yr−1 and 6.92 d yr−1, respectively. For the cold temperature indices, there were upward trends for the annual minimum of maximum temperature, by 0.09°C yr−1, and the annual minimum of minimum temperature, by 0.03°C yr−1, concurrent with the decreases in the total number cold days (TX10P), with −3.80 d yr−1, and cold nights (TN10P), with −4.33 d yr−1. The 34°C and 37°C summer days results showed significant upward trends of 4.10 d yr−1 and 0.25 d yr−1, respectively. Overall, these findings showed upward warming trends in the Klang Valley, with the minimum temperature rate increasing more than that of the maximum temperature, especially in urban areas.

Background Indoor air quality (IAQ) is a concern in kindergartens as children spend much of their time there. Yet, there is a shortage of biological indicators needed for assessing IAQ. Thus, this study evaluated IAQ using transplanted lichen Usnea misaminensis as a biological indicator. Methods Lichen samples, collected from Bukit Larut, Perak, Malaysia, were exposed to indoor and outdoor environments in an urban area (Ummi Aiman Kindergarten) and a rural area (Ummi Qaseh Pelangi Kindergarten) for 2 months during August 15 to October 14, 2019. The concentrations of 12 selected elements and the vitality of the lichens were then evaluated. Results Increased concentrations of eleven of the twelve elements deposited in the lichen samples in both urban and rural areas were observed. For both areas, the element concentrations in the samples from the indoor environment was lower than those from the outdoor environment, and those in the rural area were lower than those from in the urban area, suggesting the impacts of traffic emissions. The vitality of the lichens showed no significant change in indoor environment, compared to that in outdoor environment, indicating that even exposed to indoor environment, the lichens remained effective biological indicators as same as they were in the outdoor environment. Conclusions Lichens are effective biological indicators for both outdoor and indoor environments. Furthermore, outdoor emissions could influence IAQ, which could be problematic in densely populated areas such as kindergartens. Mitigation measures should be taken.

Benzene, toluene, ethylbenzene and xylene isomers (BTEX) are volatile organic air pollutants of concern which arise from natural and anthropogenic sources. This study aims to determine and evaluate the BTEX levels in ambient air in selected areas of Malaysia, namely: Kuala Lumpur (KL-urban), Penang (PG-urban), Bangi (BG-suburban), Langkawi (LGK-suburban) and the Danum Valley (DV-rural). Active sampling with sorbent tubes was applied in this study and samples were analysed using thermal desorption (TD) coupled with gas chromatography-mass spectrometry (GC-MS). The results show that the urban area of KL had the highest ΣBTEX (40.36 ± 6.99 μg/m3) followed by PG (30.82 ± 8.06 μg/m3). ΣBTEX concentrations in the suburban areas of LGK and BG were measured as 20.22 ± 11.42 μg/m3 and 12.36 ± 2.26 μg/m3, respectively. The rural area of DV had the lowest concentration of ΣBTEX (5.55 ± 2.54 μg/m3). The average toluene to benzene (T:B) ratio at KL, PG and LG were found to be within the range of 2.00–5.00 thus indicating vehicle emissions as the main source. The benzene level at both KL (7.43 μg/m3) and PG (5.12 μg/m3) were found to be slightly higher than the annual benchmark of 5 μg/m3 as suggested by the European Union (EU). The results of health risk assessments found that the cancer risk (CR) based on benzene concentrations in urban, suburban and rural areas was > 10−6 thus indicating a link between human cancer risks and ambient benzene exposure.

Orthosiphon aristatus (Blume) Miq., Lamiaceae, is a medicinal plant from Southeast Asia. Pharmacological effects of O. aristatus are attributed to the presence of lipophilic flavones. This study aimed to carry out accelerated stability studies on O. aristatus ethanolic extract and its nano liposomes. The extracts were exposed to four different temperatures at 30, 40, 50 and 60 °C for 6 months. The samples were analyzed at 0, 1, 2, 3, 4, 5 and 6 months by high performance liquid chromatography using rosmarinic acid, 3′-hydroxy-5,6,7,4′-tetramethoxyflavone, sinensetin and eupatorin as markers. Different chemical kinetic parameters of the markers were evaluated by Arrhenius equation to predict shelf life (t90) at different storage conditions and at room temperature. Moreover, the stability of O. aristatus ethanolic extract and O. aristatus nano liposomes were analyzes by chemical fingerprinting using FTIR spectroscopy, principal component analysis and hierarchical clustering analysis. The degradation of markers in both O. aristatus ethanolic extract and O. aristatus nano liposomes followed the first order degradation reaction (dependening on their initial concentration). The loss of marker compounds in O. aristatus ethanolic extract, stored at 30, 40, 50 and 60 °C for six months were up to 25, 52, 72 and 89% for all compounds, respectively. However, in O. aristatus nano liposomes 16, 71, 85 and 100% of compounds were lost during 6 months of storage at 30, 40, 50 and 60 °C, respectively. Therefore, the markers in O. aristatus nano liposomes seems to be more stable at a temperature below 30 °C compared to O. aristatus ethanolic extract. However, markers present in O. aristatus ethanolic extract are more stable at a higher temperature (above 30 °C). principal component analysis or hierarchical clustering analysis analyses were applied to the FTIR results in order to demonstrate the discrimination between extracts based on the storage conditions. The results show that the functional group of the components in the extracts and their chemistry relationship is influenced by the temperature setup indicating the extracts are not stable during the storage conditions. Keywords: Stability, Nano liposomes, HPLC, FTIR, PCA

The bio-efficacy of calcium silicate as foliar application in enhancing physical barrier mechanism against Pyricularia oryzae in aerobic rice was investigated. A blast-partially resistant cultivar, MR219–4 and a resistant cultivar MARDI Aerob 1 were cultivated under aerobic conditions with foliar application of calcium silicate at 3, 6 and 9 mg/L. Foliar application of calcium silicate at 9 mg/L indicated the highest rice blast disease reduction for both cultivars, MR219–4 (89.21%) and MARDI Aerob 1 (97.87%). Scanning Electron Microscope (SEM) with energy dispersive X-ray (EDX) demonstrated that MARDI Aerob 1 has uniform distribution on the dumbbell shape of silica bodies in leaf epidermis compared with MR219–4 where there was a fractured on the dumbbell shape with non-uniform distribution of silica dumbbell bodies. Besides, MARDI Aerob 1 has significantly higher Silicon (Si) weight (34.49%) compared with MR219–4 (18.29%). Both rice cultivars exhibited significant increases in Si deposition for plant treated with calcium silicate through foliar application, especially when P. oryzae was inoculated. The Si content in rice leaf shown a consistence result with the Si distribution. However, the lignin content in Si-treated rice plant was significantly increased only with P. oryzae inoculation. MARDI Aerob 1 demonstrated higher lignin content (0.74%) compared with MR219–4 (0.60%) for Si-treated and P. oryzae inoculated treatment. This study revealed that foliar application of calcium silicate at 9 mg/L enhanced the resistance of aerobic rice against P. oryzae infection through accumulation and fortification of Si in the epidermal cell wall and increased lignin content in the leaf.

The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC’16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009–2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O3 mixing ratio during MASEC’16 increased from a minimum of 5 ppb to ~ 10–13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O3 cycle has a maximum during the winter of 30 to 35 ppb between June and August and a minimum during the summer (January to February) of 10 to 20 ppb. The surface O3 mixing ratio during the summer was controlled by photochemical processes in the presence of sunlight, leading to the depletion process. During the winter, the photochemical production of surface O3 was more dominant. The NOAA-AIRS and ECMWF-MACC analysis agreed well with the MASEC’16 data but twice were higher during the expedition period. Finally, the CO past data showed the surface O3 mixing ratio was influenced by the CO mixing ratio over both the Ushuaia and Antarctic regions. Peak surface O3 and CO hourly mixing ratios reached up to ~ 38 ppb (O3) and ~ 500 ppb (CO) over Ushuaia. High CO over Ushuaia led to the depletion process of surface O3 over the region. Monthly CO mixing ratio over Antarctic (South Pole) were low, leading to the production of surface O3 over the Antarctic region.

PM2.5 released from urban sources and regional biomass fire is of great concern due to the deleterious effect on human health. This study was conducted to determine the chemical compositions andsource apportionment of PM2.5. Twenty-four-hour PM2.5 samples were collected at two urban monitoring sites in Kuala Lumpur, Malaysia, from 12 November 2013 to 15 January 2014 using a high volume air sampler (HVS). The source apportionment of PM2.5 was determined using positive matrix factorization (PMF) version 5.0. Overall, the PM2.5 mean concentrations ranged from 16 to 55 μg m−3 with a mean of 23 ± 9 μg m−3. The results of enrichment factor (EF) analysis showed that Zn, Pb, As, Cu, Cr, V, Ni, and Cs mainly originated from non-crustal sources. The dominant polycyclic aromatic hydrocarbons (PAHs) were benzo[b]fluoranthene (B[b]F), benzo[ghi]perylene (B[ghi]P), indeno[1,2,3-cd]pyrene (I[cd]P), benzo[a]pyrene (B[a]P) and benzo[k]fluoranthene (B[k]F). PMF 5.0 results showed that the secondary aerosol coupled with biomass burning was the largest contributor followed by combustion of fuel oil and road dust, soil dust source and sea salt and nitrate aerosol, accounting for 34, 25, 24 and 17% of PM2.5 mass, respectively. On the other hand, biomass and wood burning (42%) was the predominant source of PAHs followed by combustion of fossil fuel (36%) and natural gas and coal burning (22%). The broad overview of the PM2.5 sources will help to adopt adequate mitigation measures in the management of future urban air quality in this region.

The accumulation of volatile organic compounds (VOCs) in ambient air affects air quality through the generation of surface level ozone and secondary organic aerosol. A study of the distribution and source apportionment of VOCs was conducted at two stations to investigate the air quality status of Kuala Lumpur. Samples of ambient air were collected into Tedlar sampling bags using an air sampling pump and then pre-concentrated with solid-phase micro-extraction fibre. Gas chromatography–mass spectrometry (GC–MS) was employed to measure the VOC species. An absolute principal component score–multiple linear regression (APCS–MLR) model was then applied to identify the possible source contributions of VOCs. Seventeen VOCs were detected, and methylene chloride (243 ± 241 ppbv) was the most abundant species at both stations. Within the benzene, toluene, ethyl benzene and xylene group of VOCs, toluene was dominant with an average of 135 ± 202 ppbv, followed by p-xylene (41.3 ± 24.7 ppbv), ethyl benzene (34.0 ± 32.6 ppbv) and benzene (18.2 ± 12.9 ppbv). A strong correlation between benzene and toluene (p

Principal component analysis (PCA) and correlation have been used to study the variability of particle mass and particle number concentrations (PNC) in a tropical semi-urban environment. PNC and mass concentration (diameter in the range of 0.25-32.0 μm) have been measured from 1 February to 26 February 2013 using an in situ Grimm aerosol sampler. We found that the 24-h average total suspended particulates (TSP), particulate matter ≤10 μm (PM10), particulate matter ≤2.5 μm (PM2.5) and particulate matter ≤1 μm (PM1) were 14.37 ± 4.43, 14.11 ± 4.39, 12.53 ± 4.13 and 10.53 ± 3.98 μg m(-3), respectively. PNC in the accumulation mode (500 nm) was the most abundant (at about 99 %). Five principal components (PCs) resulted from the PCA analysis where PC1 (43.8 % variance) predominates with PNC in the fine and sub-microme tre range. PC2, PC3, PC4 and PC5 explain 16.5, 12.4, 6.0 and 5.6 % of the variance to address the coarse, coarser, accumulation and giant fraction of PNC, respectively. Our particle distribution results show good agreement with the moderate resolution imaging spectroradiometer (MODIS) distribution.

The specific heat capacity (C sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH–CSS blends: PPV37 (70 mass% CSS) and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J· g−1 · K−1 and (2.517 to 14.727) J · g−1· K−1, respectively. The specific heat capacity of PVOH–CSS depends on the amount of starch. The specific heat capacity of the specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific heat capacity (in J · g−1 · K−1) of PPV37 can be expressed by C sp = −17.824 + 0.063T and PPV46 by C sp = −18.047 + 0.061T, where T is the temperature (in K).