19672 research outputs found
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Diet of tropical insectivorous birds in lowland Malaysian rainforest
No full textDespite the importance of diet in avian ecology, knowledge of bird diet in tropical regions, particularly South-East Asia, is limited. Assessing predator–prey relationships of how energy flows across ecosystems provides insight into niche segregation of sympatric species. We examined induced-regurgitation samples from 15 species of insectivorous birds – 12 babblers and three flycatcher-like species – from the Krau Wildlife Reserve, central Peninsular Malaysia. The main objective of this study was to compare and characterise the diet of similar trophically insectivorous birds so as to examine the occurrence of dietary overlap or segregation. The majority of identified prey items belong to the following arthropod taxa: Coleoptera (53%), Hymenoptera (19%), Blattodea (11%), and Araneae (11%). The diet of all bird species slightly overlapped (p = 0.070) but network analysis yielded a relatively low value (R o = 0.53), indicating dietary divergence may have occurred among the studied bird species, possibly reflected by the variation in proportion of arthropod groups. A high proportion of Coleoptera and three other arthropod groups (i.e. Hymenoptera, Blattodea and Araneae) in the diet of studied birds could be related to their richness and abundance in aerial leaf-litter, the substrate preferred by most babblers. Dietary differences may further be explained by variations in bill shapes and sizes, likely corresponding to prey size. Unique foraging strategies (utilising different vertical strata, microha-bitats, and attack manoeuvres) could also lead to dietary separation among sympatric species. Flycatcher-like species were expected to flycatch different prey items (families or lower taxa) versus the gleaning birds (most babblers). This study successfully discerned more details on the diets of insectivorous birds inhabiting Malaysian forests, providing a foundation for future studies on the ecology and biology of understorey birds
A design of faceted search engine - A review
No full textThe World Wide Web (WWW) allows the people to share information and data from large database repositories globally. The amount of information is already in the billions of databases. We need to search the information with specialize tools known generically as search engine (SE). With the huge data that needs to be handled, search engines need to retrieve meaningful information intelligently, whereby only information of interest to the searcher needs to be returned. Facets (the particular aspect or feature of something being searched) can play an important role in helping the user understand an information space better. Queries techniques within faceted search will make the search results immediate and the interaction between searcher and search engine uninterrupted and focused. They can contribute to the user's understanding of the researched terms or topics. Furthermore, they are more fun and interesting to use because users directly manipulate the search controls and the results can be displayed through choices of presentation such as text displays, transition animations, graphs etc. which bring the process closer to an experience in game playing. This paper review the design of faceted search engine
Morphology, ultrastructure, and molecular phylogeny of Wangodinium sinense gen. et sp. nov. (Gymnodiniales, Dinophyceae) and revisiting of Gymnodinium dorsalisulcum and Gymnodinium impudicum
No full textThe genus Gymnodinium includes many morphologically similar species, but molecular phylogenies show that it is polyphyletic. Eight strains of Gymnodinium impudicum, Gymnodinium dorsalisulcum and a novel Gymnodinium-like species from Chinese and Malaysian waters and the Mediterranean Sea were established. All of these strains were examined with light microscopy, scanning electron microscopy and transmission electron microscopy. SSU, LSU and internal transcribed spacers rDNA sequences were obtained. A new genus, Wangodinium, was erected to incorporate strains with a loop-shaped apical structure complex (ASC) comprising two rows of amphiesmal vesicles, here referred to as a new type of ASC. The chloroplasts of Wangodinium sinense are enveloped by two membranes. Pigment analysis shows that peridinin is the main accessory pigment in W. sinense. Wangodinium differs from other genera mainly in its unique ASC, and additionally differs from Gymnodinium in the absence of nuclear chambers, and from Lepidodinium in the absence of Chl b and nuclear chambers. New morphological information was provided for G. dorsalisulcum and G. impudicum, e.g., a short sulcal intrusion in G. dorsalisulcum; nuclear chambers in G. impudicum and G. dorsalisulcum; and a chloroplast enveloped by two membranes in G. impudicum. Molecular phylogeny was inferred using maximum likelihood and Bayesian inference with independent SSU and LSU rDNA sequences. Our results support the classification of Wangodinium within the Gymnodiniales sensu stricto clade and it is close to Lepidodinium. Our results also support the close relationship among G. dorsalisulcum, G. impudicum, and Barrufeta. Further research is needed to assign these Gymnodinium species to Barrufeta or to erect new genera
Isolation of actinomycetes with antibacterial activity against multi-drug resistant bacteria
No full textAims: To isolate and characterise actinomycetes from various sources of soil samples (fruit orchard, dipterocarp forest and oil palm plantation) and to screen these isolates for antibacterial activity against multi-drug resistant bacteria. Methodology and results: A total of 158 fast-growing actinomycete isolates with different colony morphology were subjected to primary cross-streak and secondary well diffusion screening. Six isolates (OP1E, OP7A, OP2A-C, MG1A, UT9C1 and UT7E) were found to inhibit at least one of the seven multi-drug resistant (MDR) bacteria. MG1A exhibited the strongest and broadest spectrum of antibacterial activity against 6 MDR bacteria tested. These isolates were identified as Streptomyces species based on 16S rRNA gene sequence analysis. Further morphological and biochemical analysis revealed that MG1A was highly similar to S. griseocarneus (98.36%) whereas OP1E and OP2A-C were similar to S. parvulus (99.93% and 99.51% respectively). Preliminary identification using LCMS/MS and database search revealed that the major compound in the extract of OP2A-C could be dactinomycin (1255.4170 g/mol). Other antibacterial compounds in the extracts remain to be identified. Conclusion, significance and impact of study: Soil actinomycetes with antibacterial activity against MDR bacteria were isolated not only from undisturbed natural soils but cultivated soils. These isolates were characterised, identified and the antibacterial compounds were extracted for further study. The isolates could serve as a potential source for the development of new and sustainable compounds against MDR bacteria
Tailoring tail-free nematogen of ethynylated-schiff base and its evaluation as solution-processable OLED emitting material
No full textA new rigid core dye comprised ESB-NO2 of chromophore moieties of acetylide (C≡C), Schiff base (C˭N) and nitro (NO2) was successfully synthesized to demonstrate tail-free nematogen as emitting material for organic light-emitting diode (OLED). The relationship between liquid crystal molecular structure, phase transition temperature and electroluminescence behaviour were evaluated. The mesomorphic properties of ESB-NO2 were identified via polarized optic microscopy (POM) which displayed nematic phase of Schlieren textures and their corresponding transition enthalpies were respectively recorded at 25.15 kJ mol−1. The photoluminescence behaviours of ESB-NO2 have been verified at λem,max = 538 nm where this emission are for its π→π * transition, intramolecular charge transfer (ICT) absorptions and fluoresce characters. Having ESB-NO2 as liquid crystalline material, OLED was constructed featuring single-layer indium tin oxide (ITO) coated substrate/ESB-NO2/Au via solution-casting method. The result revealed the single layer ESB-NO2 film displayed satisfactory electroluminescence with intense yellow emission under different direct current (DC) voltages supply. These findings indicate the practicability of designing tail-free nematogenic compounds as promising solution-processed OLED materials
Calcium chloride dihydrate affects the biological properties of white mineral trioxide aggregate on dental pulp stem cells: An in vitro study
No full textIntroduction: Biological testing of biomaterials on dental pulp stem cells (DPSCs) is one recent advance in endodontic research. The aim of this study was to compare the cytotoxicity, cell attachment properties, and dentinogenic differentiation potential of extracts of white mineral trioxide aggregate (WMTA)/calcium chloride dihydrate CaCl2.2H2O combination (fast-set WMTA [FS WMTA]) to that of WMTA on DPSCs. Materials and Methods: The cytotoxicity and cell attachment properties were evaluated on DPSCs using methyl-thiazol-diphenyltetrazolium assay and under scanning electron microscope, respectively. After 1, 3, and 7 days of incubation, the expression of four dentinogenic gene markers (BGLAP, DSPP, RUNX2, and SPP1) was examined using the real-time polymerase chain reaction. Mann-Whitney test and one-way analysis of variance were used for statistical analysis (P = 0.05). Results: While WMTA showed favorable cytotoxicity and cell attachment properties, FS WMTA demonstrated severe/moderate cytotoxicity at three successive concentrations (P < 0.05), and the cell attachment properties were less favorable. However, DPSCs treated with FS WMTA extracts showed higher expressions of dentinogenic gene markers than WMTA (P < 0.05). BGLAP and SPP1 were down- and up-regulated in both groups at all-time intervals, respectively. DSPP was upregulated only in WMTA at day 3 compared to days 1 and 7 in FS WMTA. RUNX2 was upregulated at all-time intervals only in FS WMTA. Conclusions: The addition of CaCl2.2H2O increases the cytotoxicity but enhances the dentinogenic differentiation potential of WMTA on DPSCs
Double gene targeting PCR assay for the detection of Crocodylus porosus in commercial products
No full textThe demand for crocodile meat is quickly growing because of its exotic and organoleptic appeal and also the low content of cholesterol and lipids. Moreover, crocodile oil and blood have been used in alternative medicines for treating asthma and several other ailments since ancient times. Furthermore, crocodile hides have great demand in leather industries. All of these have collectively contributed to the extensive hunting, illegal trading and consequent decline of crocodiles in most parts of the world. To keep space with the growing demands, some crocodile species such as Crocodylus porosus have been raised in farms and its commercial trades have been legalised. However, demand for wild crocodiles in foods and medicines has continued in high gear. Recently, several DNA-based methods have been proposed for crocodile detection, but those assays are based on single gene and longer-sized amplicon targets that break down during extensive processing. To address this gap, here we developed and validated a highly stable double gene targeted multiplex PCR assay for the identification of C. porosus materials in commercial products. The assay involved two short sites from C. porosus atp6 (77 bp) and cytb (127 bp) genes and a universal internal control (99 bp) for eukaryotes. The PCR primers were cross-tested against 18 species and validated under pure and mixed matrices under extensive boiling, autoclaving and microwave cooking conditions. Finally, it was used to identify five crocodile-based commercial products. The lower limits of detection for atp6 and cytb genes were 0.001 ng and 0.01 ng DNA, respectively, in pure meat and 1% under mixed matrices. Some inherent features, such as 77–127 bp amplicon sizes, exceptional stability and superior sensitivity, suggested the assay could be used for the identification of C. porosus in any forensic specimen
Effect of iron impurity in liquid phase exfoliated tungsten disulfide based ultraviolet heterojunction photodetector
No full textPhotoconductivity characteristics of iron (Fe) impurity in a tungsten disulfide (WS2) based ultraviolet (UV) heterojunction photodetector are and presented On: Wed,inin WS impurities through electrolysis process during current–voltage (I–V) characterizationis found the2 sample by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis Unexpectedly, this Fe impurity enhances the performance of the WS2 based UV heterojunction photodetector due to the increase of the electron concentration in the WS2 structural matrix. Photon responsivity is observed to increase by 231% while the dark current reduces by 80% as compared to pure WS2 samples. The highest responsivity achieved is 5.9 AW−1 when the input optical power is 7.8 μW at 382 nm with a bias voltage of 10 V and a dark current as low as 6 μA. The enhancement due to the Fe impurities will encourage additional studies into the doping and hybridization of metals into two dimensional (2D) materials for better photodetector performance
Heterojunction photodetector based on graphene oxide sandwiched between ITO and p-Si
No full textThe drop casting method is utilized on indium tin oxide (ITO)-coated glass in order to prepare a sandwiched ITO/graphene oxide (ITO/GO) with silicon dioxide/p-type silicon (SiO2/p-Si) heterojunction photodetector. The partially sandwiched GO layer with SiO2/p-Si substrate exhibits dual characteristics as it showed good sensitivity towards the illumination of infrared (IR) laser at wavelength of 974 nm. Excellent photoconduction is also observed for current–voltage (I–V) characteristics at various laser powers. An external quantum efficiency greater than 1 for a direct current bias voltage of 0 and 3 V reveals significant photoresponsivity of the photodetector at various laser frequency modulation at 1, 5 and 9 Hz. The rise times are found to be 75, 72 and 70 μs for 1, 5 and 9 Hz while high fall times 455, 448 and 426 are measured for the respective frequency modulation. The fabricated ITO/GO-SiO2/p-Si sandwiched heterojunction photodetector can be considered as a good candidate for applications in the IR regions that do not require a high-speed response
The properties of hydroxyapatite ceramic coatings produced by plasma electrolytic oxidation
No full textCalcium phosphate coatings produced on the surface of Ti6Al4V by plasma electrolytic oxidation (PEO) using different concentrations of hydroxyapatite (HA) in a 0.12 M Na3PO4 (NAP) electrolyte solution was investigated. It was found that the amount of calcium phosphate particles infiltrated into the coating layer as well as the thickness and the surface roughness of the coating increased with increasing HA concentration. The porosity of the ceramic coatings indicated an inverse relationship with the concentration of HA particles dispersed in the NAP solution. The result also demonstrates that higher scratch adhesive strength was achieved using 1.5 g/L HA solution, producing a critical load of 2099 mN, while 0 g/L HA only produced a critical load of 1247 mN. The adhesion becomes independent of thickness when the concentration of HA exceeds 1.5 g/L. The failure of the coating was characterized by large periodic hemispherical chipping, while intermittent delamination was noticed with the coating embedded with HA particles. This study demonstrate the viability of using PEO to produce a thin layer of HA ceramic coating on Ti6Al4V suitable for biomedical applications