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Evaluation on the decomposability of tropical forest peat soils after conversion to an oil palm plantation

Sangok FE, Maie N, Melling L, Watanabe A

Sci Total Environ, 2017 Jun 01;587-588:381-388.
PMID: 28242223 DOI: 10.1016/j.scitotenv.2017.02.165

To understand the variations in the decomposability of tropical peat soil following deforestation for an oil palm plantation, a field incubation experiment was conducted in Sarawak, Malaysia. Peat soils collected from three types of primary forest, namely Mixed Peat Swamp (MPS; Gonystylus-Dactylocladus-Neoscrotechinia association), Alan Batu (ABt; Shorea albida-Gonstylus-Strenonurus association), and Alan Bunga (ABg; Shorea albida association), were packed in polyvinyl chloride pipes and installed in an oil palm plantation. Carbon dioxide (CO2) and methane (CH4) fluxes from soil were monthly measured for 3years. Environmental variables including soil temperature, soil moisture content, and groundwater table were also monitored. The pH, loss on ignition, and total carbon (C) content were similar among the three soils, while total N content was larger in the MPS than in the ABg soils. Based on13C nuclear magnetic resonance (NMR) spectroscopy, C composition of the MPS and ABg soils was characterized by the largest proportion of C present as alkyl C and O-alkyl C, respectively. The C composition of the ABt soil was intermediate between the MPS and ABg soils. The CO2fluxes from the three soils ranged from 78 to 625mgCm-2h-1with a negative correlation to groundwater level. The CH4fluxes ranged from -67 to 653μgCm-2h-1. Both total CO2and CH4fluxes were larger in the order ABg>ABt>MPS (P<0.05). Annual rate of peat decomposition as was estimated from cumulative C loss differed up to 2 times, and the rate constant in exponential decay model was 0.033y-1for the MPS soil and 0.066y-1for the ABg soil. The field incubation results of the three forest peat soils seem to reflect the difference in the labile organic matter content, represented by polysaccharides.
Composition of dissolved organic nitrogen in rivers associated with wetlands

Watanabe A, Tsutsuki K, Inoue Y, Maie N, Melling L, Jaffé R

Sci Total Environ, 2014 Sep 15;493:220-8.
PMID: 24946034 DOI: 10.1016/j.scitotenv.2014.05.095

As basic information for assessing reactivity and functionality of wetland-associated dissolved organic matter (DOM) based on their composition and structural properties, chemical characteristics of N in ultrafiltered DOM (UDON; >1 kD) isolated from wetland-associated rivers in three climates (cool-temperate, Hokkaido, Japan; sub-tropical, Florida, USA; tropical, Sarawak, Malaysia) were investigated. The UDON was isolated during dry and wet seasons, or during spring, summer, and autumn. The proportion of UDON present as humic substances, which was estimated as the DAX-8 adsorbed fraction, ranged from 47 to 91%, with larger values in the Sarawak than at the other sites. The yield of hydrolyzable amino acid N ranged 1.24 to 7.01 mg g(-1), which correlated positively to the total N content of UDOM and tended to be larger in the order of Florida>Hokkaido>Sarawak samples. X-ray photoelectron N1s spectra of UDON showed a strong negative correlation between the relative abundances of amide/peptide N and primary amine N. The relative abundances of amide/peptide N and primary amine N in the Sarawak samples were smaller (70-76%) and larger (20-23%) respectively compared to those (80-88% and 4-9%) in the Florida and Hokkaido samples. Assuming terminal amino groups and amide N of peptides as major constituents of primary amine N and amide/peptide N, respectively, the average molecular weight of peptides was smaller in the Sarawak samples than that in the Florida and Hokkaido samples. Seasonal variations in UDON composition were scarce in the Sarawak and Florida samples, whereas the distribution of humic substance-N and nonhumic substance-N and compositions of amino acids and N functional groups showed a clear seasonality in the Hokkaido samples. While aromatic N increased from spring to autumn, contributions from fresh proteinaceous materials were also enhanced during autumn, resulting in the highest N content of UDOM for this season.
Contributions of humic substances to the dissolved organic carbon pool in wetlands from different climates

Watanabe A, Moroi K, Sato H, Tsutsuki K, Maie N, Melling L, et al.

Chemosphere, 2012 Aug;88(10):1265-8.
PMID: 22564456 DOI: 10.1016/j.chemosphere.2012.04.005

Wetlands are an important source of DOM. However, the quantity and quality of wetlands' DOM from various climatic regions have not been studied comprehensively. The relationship between the concentrations of DOM (DOC), humic substances (HS) and non-humic substances (NHS) in wetland associated sloughs, streams and rivers, in cool temperate (Hokkaido, Japan), sub-tropical (Florida, USA), and tropical (Sarawak, Malaysia) regions was investigated. The DOC ranged from 1.0 to 15.6 mg CL(-1) in Hokkaido, 6.0-24.4 mg CL(-1) in Florida, and 18.9-75.3 mg CL(-1) in Sarawak, respectively. The relationship between DOC and HS concentrations for the whole sample set was regressed to a primary function with y-intercept of zero (P<0.005) and a slope value of 0.841. A similar correlation was observed between DOC and NHS concentrations, with a smaller slope value of 0.159. However, the correlation coefficient of the latter was much larger when the data was regressed to a logarithmic curve. These observations suggest the presence of a general tendency that the increased DOC in the river waters was mainly due to the increased supply of HS from wetland soils, whereas the rate of the increase in the NHS supply has an upper limit which may be controlled by primary productivity.
Fulltext Impact of Diverse Parameters on the Physicochemical Characteristics of Green-Synthesized Zinc Oxide-Copper Oxide Nanocomposites Derived from an Aqueous Extract of Garcinia mangostana L. Leaf

Chan YB, Aminuzzaman M, Tey LH, Win YF, Watanabe A, Djearamame S, et al.

Materials (Basel), 2023 Aug 02;16(15).
PMID: 37570124 DOI: 10.3390/ma16155421

Compared to conventional metal oxide nanoparticles, metal oxide nanocomposites have demonstrated significantly enhanced efficiency in various applications. In this study, we aimed to synthesize zinc oxide-copper oxide nanocomposites (ZnO-CuO NCs) using a green synthesis approach. The synthesis involved mixing 4 g of Zn(NO3)2·6H2O with different concentrations of mangosteen (G. mangostana) leaf extract (0.02, 0.03, 0.04 and 0.05 g/mL) and 2 or 4 g of Cu(NO3)2·3H2O, followed by calcination at temperatures of 300, 400 and 500 °C. The synthesized ZnO-CuO NCs were characterized using various techniques, including a UV-Visible spectrometer (UV-Vis), photoluminescence (PL) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis and Field Emission Scanning Electron Microscope (FE-SEM) with an Energy Dispersive X-ray (EDX) analyzer. Based on the results of this study, the optical, structural and morphological properties of ZnO-CuO NCs were found to be influenced by the concentration of the mangosteen leaf extract, the calcination temperature and the amount of Cu(NO3)2·3H2O used. Among the tested conditions, ZnO-CuO NCs derived from 0.05 g/mL of mangosteen leaf extract, 4 g of Zn(NO3)2·6H2O and 2 g of Cu(NO3)2·3H2O, calcinated at 500 °C exhibited the following characteristics: the lowest energy bandgap (2.57 eV), well-defined Zn-O and Cu-O bands, the smallest particle size of 39.10 nm with highest surface area-to-volume ratio and crystalline size of 18.17 nm. In conclusion, we successfully synthesized ZnO-CuO NCs using a green synthesis approach with mangosteen leaf extract. The properties of the nanocomposites were significantly influenced by the concentration of the plant extract, the calcination temperature and the amount of precursor used. These findings provide valuable insights for researchers seeking innovative methods for the production and utilization of nanocomposite materials.
Fulltext Soil CO2 and CH4 fluxes from different forest types in tropical peat swamp forest

Busman NA, Melling L, Goh KJ, Imran Y, Sangok FE, Watanabe A

Sci Total Environ, 2023 Feb 01;858(Pt 2):159973.
PMID: 36347298 DOI: 10.1016/j.scitotenv.2022.159973

Information on temporal and spatial variations in soil greenhouse gas (GHG) fluxes from tropical peat forests is essential to predict the influence of climate change and estimate the effects of land use on global warming and the carbon (C) cycle. To obtain such basic information, soil carbon dioxide (CO2) and methane (CH4) fluxes, together with soil physicochemical properties and environmental variables, were measured at three major forest types in the Maludam National Park, Sarawak, Malaysia, for eight years, and their relationships were analyzed. Annual soil CO2 fluxes ranged from 860 to 1450 g C m⁻2 yr⁻1 without overall significant differences between the three forest sites, while soil CH4 fluxes, 1.2-10.8 g C m⁻2 yr⁻1, differed. Differences in GHG fluxes between dry and rainy seasons were not necessarily significant, corresponding to the extent of seasonal variation in groundwater level (GWL). The lack of significant differences in soil CO2 fluxes between the three sites could be attributed to set-off between the negative and positive effects of the decomposability of soil organic matter as estimated by pyrophosphate solubility index (PSI) and GWL. The impact of El-Niño on annual CO2 flux also varied between the sites. The variation in soil CH4 fluxes from the three sites was enhanced by variations in temperature, GWL, PSI, and soil iron (Fe) content. A positive correlation was observed between the annual CH4 flux and GWL at only one site, and the influence of soil properties was more pronounced at the site with the lowest GWL and the highest PSI. Variation in annual CH4 fluxes was controlled more strongly by temperature where GWL was the highest and GWL and plant growth fluctuations were the least. Inter-annual variations in soil CO2 and CH4 fluxes confirmed the importance of long-term monitoring of these at multiple sites supporting different forest types.
Fulltext Corrigendum to "Soil CO2 and CH4 fluxes from different forest types in tropical peat swamp forest" [Sci. Total Environ. 858 (2023) 159973]

Busman NA, Melling L, Goh KJ, Imran Y, Sangok FE, Watanabe A

Sci Total Environ, 2024 Feb 20;912:168867.
PMID: 38040577 DOI: 10.1016/j.scitotenv.2023.168867
Fulltext Muntingia calabura Leaves Mediated Green Synthesis of CuO Nanorods: Exploiting Phytochemicals for Unique Morphology

Selvanathan V, Aminuzzaman M, Tey LH, Razali SA, Althubeiti K, Alkhammash HI, et al.

Materials (Basel), 2021 Oct 25;14(21).
PMID: 34771914 DOI: 10.3390/ma14216379

In this study, phytochemical assisted nanoparticle synthesis was performed using Muntingia calabura leaf extracts to produce copper oxide nanoparticles (CuO NPs) with interesting morphology. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis of the biosynthesized CuO NPs reveal formation of distinct, homogeneous, and uniform sized CuO nanorods structure with thickness and length of around 23 nm and 79 nm, respectively. Based on Fourier-transform infrared (FTIR) analysis, the unique combinations of secondary metabolites such as flavonoid and polyphenols in the plant extract are deduced to be effective capping agents to produce nanoparticles with unique morphologies similar to conventional chemical synthesis. X-ray diffraction (XRD) analysis verified the monoclinical, crystalline structure of the CuO NPs. The phase purity and chemical identity of the product was consolidated via X-Ray photoelectron spectroscopy (XPS) and Raman spectroscopic data which indicate the formation of a single phase CuO without the presence of other impurities. The direct and indirect optical band gap energies of the CuO nanorods were recorded to be 3.65 eV and 1.42 eV.
An outbreak of histoplasmosis among healthy young Japanese women after traveling to Southeast Asia

Ohno H, Ogata Y, Suguro H, Yokota S, Watanabe A, Kamei K, et al.

Intern. Med., 2010;49(5):491-5.
PMID: 20190491

Histoplasmosis, caused by Histoplasma capsulatum, is an endemic mycosis in many countries of the world except for Japan. Outbreaks of histoplasmosis among Japanese people are very rare and are mainly imported by travelers. We report an outbreak of histoplasmosis among healthy Japanese people who traveled to a resort area in Southeast Asia. Three young Japanese women traveled to Langkawi island, Malaysia and stayed on the island for five days without visiting caves, a known reservoir of H. capsulatum. All three individuals developed flu-like symptoms with multiple nodule shadows on chest X rays or chest CT scans at around ten days after their return to Japan. Serum samples obtained from the three subjects were positive for anti-Histoplasma antibody and specific PCR for H. capsulatum on lung biopsy specimens and the serum from one patient was positive. The clinical course of all three patients improved without the use of anti-fungal agents and no recurrence has been confirmed. Clinical attendants should consider histoplasmosis when they see patients with flu-like symptoms with abnormal chest X-rays after visiting H. capsulatum endemic areas, especially Southeast Asia.
An Injectable Hyaluronic Acid Hydrogel Promotes Intervertebral Disc Repair in a Rabbit Model

Inoue M, Isa ILM, Orita S, Suzuki-Narita M, Inage K, Shiga Y, et al.

Spine (Phila Pa 1976), 2021 Aug 01;46(15):E810-E816.
PMID: 34228691 DOI: 10.1097/BRS.0000000000003921

STUDY DESIGN: An in vivo model to study the effect of an injectable hyaluronic acid (HA) hydrogel following puncture-induced lumbar disc injury in rabbits.
OBJECTIVES: The aim of this study was to determine the efficacy of an injectable HA hydrogel to maintain disc height and tissue hydration, promote structural repair, and attenuate inflammation and innervation in the lumbar discs.
SUMMARY OF BACKGROUND DATA: Previously, we have demonstrated that HA hydrogel alleviated inflammation, innervation, and pain to promote disc repair. Nevertheless, the effect of an injectable HA hydrogel in the lumbar disc in a weight-bearing animal model was not performed.
METHODS: We have adopted a surgically puncture-induced disc injury at lumbar levels in a rabbit model. The discs were grouped into sham, puncture with water injection, and puncture with HA hydrogel injection. Postoperatively, we measured changes in disc height using x-ray. We used magnetic resonance imaging to assess disc degeneration on tissue hydration after euthanasia. Post-mortem, we determined histological changes, innervation (PGP9.5) and inflammation (interleukin [IL]-6, IL-1β, and tumor necrosis factor [TNF]-α) in the discs.
RESULTS: We have demonstrated a significant reduction of disc height and T2/T1ρ mapping with histological evidence of degenerative discs, increase of innervation and inflammation in puncture-induced disc injury over time. In the HA hydrogel group, disc height was increased at weeks four and eight. A slight increase of T2 mapping, but significantly in T1ρ mapping, was observed in the HA hydrogel group at week 8. We observed homogenous NP distribution and organised AF lamellae at week eight and a slight reduced innervation score in the treatment group. HA hydrogel significantly downregulated IL-6 expression at day 1. This, however, was only slightly reduced for IL-1β and TNF-α.
CONCLUSION: An injectable HA hydrogel had the protective effects in suppressing the loss of disc height, promoting tissue hydration for structural repair, and attenuating inflammation and innervation to prevent further disc degeneration.Level of Evidence: N/A.
Fulltext Comparative global epidemiology of influenza, respiratory syncytial and parainfluenza viruses, 2010-2015

Lam TT, Tang JW, Lai FY, Zaraket H, Dbaibo G, Bialasiewicz S, et al.

J Infect, 2019 10;79(4):373-382.
PMID: 31323249 DOI: 10.1016/j.jinf.2019.07.008

OBJECTIVES: To improve our understanding of the global epidemiology of common respiratory viruses by analysing their contemporaneous incidence at multiple sites.
METHODS: 2010-2015 incidence data for influenza A (IAV), influenza B (IBV), respiratory syncytial (RSV) and parainfluenza (PIV) virus infections were collected from 18 sites (14 countries), consisting of local (n = 6), regional (n = 9) and national (n = 3) laboratories using molecular diagnostic methods. Each site submitted monthly virus incidence data, together with details of their patient populations tested and diagnostic assays used.
RESULTS: For the Northern Hemisphere temperate countries, the IAV, IBV and RSV incidence peaks were 2-6 months out of phase with those in the Southern Hemisphere, with IAV having a sharp out-of-phase difference at 6 months, whereas IBV and RSV showed more variable out-of-phase differences of 2-6 months. The tropical sites Singapore and Kuala Lumpur showed fluctuating incidence of these viruses throughout the year, whereas subtropical sites such as Hong Kong, Brisbane and Sydney showed distinctive biannual peaks for IAV but not for RSV and PIV.
CONCLUSIONS: There was a notable pattern of synchrony of IAV, IBV and RSV incidence peaks globally, and within countries with multiple sampling sites (Canada, UK, Australia), despite significant distances between these sites.

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