Displaying all 6 publications

  1. Toki W, Matsuo S, Pham HT, Meleng P, Lee CY
    Naturwissenschaften, 2019 Aug 27;106(9-10):50.
    PMID: 31456022 DOI: 10.1007/s00114-019-1645-6
    The cavities of bamboos (Poaceae) are used by various animals. Most of the animals access these cavities either by existing cracks or by excavating bamboos with soft walls or small, thin-walled bamboos. Only a few animals excavate into the cavities of large and thick- and hard-walled internodes of mature bamboos. We studied two lizard beetle species (Coleoptera: Erotylidae: Languriinae), Doubledaya ruficollis and Oxylanguria acutipennis, that excavate into large internode cavities of recently dead mature bamboos and have morphological modifications. We observed that females of D. ruficollis used their mandibles to bore oviposition holes on Schizostachyum sp. (mean wall thickness = 3.00 mm) and O. acutipennis did so on Dendrocalamus sp. (3.37 mm) bamboos. Previous studies suggested that the markedly asymmetrical mandibles and needle-like ovipositors of females in the genus Doubledaya are adaptive traits for excavating hard-walled bamboos for oviposition. Therefore, we measured their mandibular lengths and ovipositor lengths. D. ruficollis females had greater asymmetry in the mandibles and shorter and less-sclerotized ovipositors than females of congeners using small bamboos. In contrast, O. acutipennis females had slightly asymmetrical mandibles and elongated, well-sclerotized ovipositors. Oviposition holes of D. ruficollis were cone-shaped (evenly tapering), whereas those of O. acutipennis were funnel-shaped (tube-like at the internal apex). This suggests that D. ruficollis females excavate oviposition holes using the mandibles only, and O. acutipennis females use both the mandibles and ovipositors. These differences suggest different oviposition-associated morphological specialization for using large bamboos: the extremely asymmetrical mandibles in D. ruficollis and elongated, needle-like ovipositors in O. acutipennis.
  2. Takaoka H, Sofian-Azirun M, Ya'cob Z, Chen CD, Lau KW, Pham HT
    Zootaxa, 2014;3838(3):347-66.
    PMID: 25081781 DOI: 10.11646/zootaxa.3838.3.6
    Four new species of black flies are described, and three others are reported as newly recorded, based on adults reared from pupae, pupae and larvae collected in and near Tam Dao National Park, Vinh Phuc Province, Vietnam. New species include Simulium (Gomphostilbia) hongthaii sp. nov., S. (G.) tamdaoense sp. nov. (both species placed in the asakoae species-group), S. (Simulium) taythienense sp. nov. and S. (S.) xuandai sp. nov. (the two latter species placed in the striatum species-group). Newly recorded species are S. (G.) brinchangense Takaoka, Sofian-Azirun & Hashim, S. (Nevermannia) aureohirtum Brunetti and S. (S.) brevipar Takaoka & Davies. These discoveries increase the number of species of black flies known in Vietnam from 21 to 28. 
  3. Takaoka H, Sofian-Azirun M, Ya'cob Z, Chen CD, Lau KW, Pham HT
    Trop Biomed, 2014 Dec;31(4):742-8.
    PMID: 25776600 MyJurnal
    A total of 29 female black flies were captured by a hand net as they swarmed around humans in Tam Dao National Park, Vinh Phuc Province, Vietnam. They included one species of the subgenus Gomphostilbia (Simulium (Gomphostilbia) asakoae Takaoka & Davies) and five species of the subgenus Simulium, of which one species is described as Simulium (Simulium) vietnamense sp. nov. and the other four species (S. (S.) chungi Takaoka & Huang, S. (S.) grossifilum Takaoka & Davies, S. (S.) maenoi Takaoka & Choochote, and S. (S.) rufibasis Brunetti) are newly recorded from Vietnam.
  4. Lim SS, Fontmorin JM, Pham HT, Milner E, Abdul PM, Scott K, et al.
    Sci Total Environ, 2021 Jul 01;776:145934.
    PMID: 33647656 DOI: 10.1016/j.scitotenv.2021.145934
    Microbial fuel cells (MFCs) that simultaneously remove organic contaminants and recovering metals provide a potential route for industry to adopt clean technologies. In this work, two goals were set: to study the feasibility of zinc removal from industrial effluents using MFCs and to understand the removal process by using reaction rate models. The removal of Zn2+ in MFC was over 96% for synthetic and industrial samples with initial Zn2+ concentrations less than 2.0 mM after 22 h of operation. However, only 83 and 42% of the zinc recovered from synthetic and industrial samples, respectively, was attached on the cathode surface of the MFCs. The results marked the domination of electroprecipitation rather than the electrodeposition process in the industrial samples. Energy dispersive X-ray (EDX) analysis showed that the recovered compound contained not only Zn but also O, evidence that Zn(OH)2 could be formed. The removal of Zn2+ in the MFC followed a mechanism where oxygen was reduced to hydroxide before reacting with Zn2+. Nernst equations and rate law expressions were derived to understand the mechanism and used to estimate the Zn2+ concentration and removal efficiency. The zero-, first- and second-order rate equations successfully fitted the data, predicted the final Zn2+ removal efficiency, and suggested that possible mechanistic reactions occurred in the electrolysis cell (direct reduction), MFC (O2 reduction), and control (chemisorption) modes. The half-life, t1/2, of the Zn2+ removal reaction using synthetic and industrial samples was estimated to be 7.0 and 2.7 h, respectively. The t1/2 values of the controls (without the power input from the MFC bioanode) were much slower and were recorded as 21.5 and 7.3 h for synthetic and industrial samples, respectively. The study suggests that MFCs can act as a sustainable and environmentally friendly technology for heavy metal removal without electrical energy input or the addition of chemicals.
  5. Nguyen VH, Nguyen BD, Pham HT, Lam SS, Vo DN, Shokouhimehr M, et al.
    Sci Rep, 2021 Feb 11;11(1):3641.
    PMID: 33574397 DOI: 10.1038/s41598-020-80886-x
    In this work, we proposed a facile approach to fabricate a superhydrophobic surface for anti-icing performance in terms of adhesive strength and freezing time. A hierarchical structure was generated on as-received Al plates using a wet etching method and followed with a low energy chemical compound coating. Surfaces after treatment exhibited the great water repellent properties with a high contact angle and extremely low sliding angle. An anti-icing investigation was carried out by using a custom-built apparatus and demonstrated the expected low adhesion and freezing time for icephobic applications. In addition, we proposed a model for calculating the freezing time. The experimented results were compared with theoretical calculation and demonstrated the good agreement, illustrating the importance of theoretical contribution in design icephobic surfaces. Therefore, this study provides a guideline for the understanding of icing phenomena and designing of icephobic surfaces.
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