19672 research outputs found
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Magnetically directed antioxidant and antimicrobial agent: synthesis and surface functionalization of magnetite with quercetin
No full textOxidative stress can be reduced substantially using nanoantioxidant materials by tuning its surface morphological features up to a greater extent. The physiochemical, biological and optical properties of the nanoantioxidants can be altered by controlling their size and shape. In view of that, an appropriate synthesis technique should be adopted with optimization of the process variables. Properties of magnetite nanoparticles (IONP) can be tailored to upgrade the performance of biomedicine. Present research deals with the functionalization IONP using a hydrophobic agent of quercetin (Q). The application of quercetin will control its size using both the functionalization method including in-situ and post-synthesis technique. In in-situ techniques, the functionalized magnetite nanoparticles (IONP@Q) have average particles size 6 nm which are smaller than the magnetite (IONP) without functionalization. After post functionalization technique, the average particle size of magnetite IONP@Q2 determined was 11 nm. The nanoparticles also showed high saturation magnetization of about 51-59 emu/g. Before starting the experimental lab work, Prediction Activity Spectra of Substances (PASS) software was used to have a preliminary idea about the biological activities of Q. The antioxidant activity was carried out using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The antibacterial studies were carried out using well diffusion method. The results obtained were well supported by the simulated results. Furthermore, the values of the half maximal inhibitory concentration (IC50) of the DPPH antioxidant assay were decreased using the functionalized one and it exhibited a 2-3 fold decreasing tendency than the unfunctionalized IONP. This exhibited that the functionalization process can easily enhance the free radical scavenging properties of IONPs up to three times. MIC values confirms that functionalized IONP have excellent antibacterial properties against the strains used (Staphylococcus aureus, Bacillus subtilis and Escherichia coli) and fungal strains (Aspergillus niger, Candida albicans, Trichoderma sp. and Saccharomyces cerevisiae). The findings of this research showed that the synthesized nanocomposite has combinatorial properties (magnetic, antioxidant and antimicrobial) which can be considered as a promising candidate for biomedical applications. It can be successfully used for the development of biomedicines which can be subsequently applied as antioxidant, anti-inflammatory, antimicrobial and anticancer agents. © 2019 PeerJ Inc.. All rights reserved
An effective back-off selection technique for reliable beacon reception in VANETs
No full textIn safety-critical scenarios, reliable reception of beacons transmitted by a subject vehicle is critical to avoid vehicle collision. According to the employed contention window sizes in IEEE 802.11p, beacons are transmitted with a small contention window size. As a result, multiple vehicles contend for the shared channel access by selecting the same back-off slot. This is a perfect recipe for synchronous collisions wherein reliable beacon delivery cannot be guaranteed for any vehicle. We consider the problem of selecting the back-off slots from the current contention window to provide reliable delivery of beacons transmitted by a subject vehicle to its neighbors. Given a safety scenario, we propose a Pseudo-Random Number Generator (PRNG)-inspired back-off selection (PBS) technique. The proposed technique works on the hypothesis that synchronous collisions of beacons transmitted by a subject vehicle can be reduced if all its neighbors select different back-off slots (ie, not the back-off slot selected by the subject vehicle). The discrete-event simulations demonstrate that PBS can increase the overall message reception from a subject vehicle, in comparison with the uniform random probability back-off selection in IEEE 802.11p. © 2019 John Wiley & Sons, Ltd
One-step facile synthesis of poly(N-vinylcarbazole)-polypyrrole/graphene oxide nanocomposites: enhanced solubility, thermal stability and good electrical conductivity
No full textPoly (N-vinylcarbazole)-polypyrrole/graphene oxide (PNVC-Ppy/GO) nanocomposites have been successfully prepared by one-step chemical oxidative polymerization using ferric chloride hexahydrate in the presence of dodecyl benzene sulfonic acid. The composite formation, morphology and the crystallinity of the composite have been characterized by FTIR spectroscopy, FESEM, and XRD, respectively. The incorporation of graphene oxide into the PNVC-Ppy matrix induces interaction between graphene oxide and PNVC-Ppy via hydrogen bonding and π–π* stacking. This π–π* stacking between the GO layers and PNVC-Ppy produces longer conjugation length leading to a higher solubility in organic solvents and enhanced electron mobility. The information of conjugation chain length and charge transfer capacity at the interface of the composite has been obtained from the Raman spectroscopy and photolumincience spectroscopy. The improved thermal stability and electrical d.c. conductivity (0.123 S/cm) of the resulting PNVC-Ppy/GO composite compared to the PNVC–Ppy copolymer (0.08 S/cm) is attributed to the incorporation of graphene oxide in the composite. © 2019, © 2019 Taylor & Francis Group, LLC
The human nature: Divinity of man in IBN Arabi's and Shankara's perspectives
No full textArabi's school of thought and Shankara's worldview have much in common. One of issue on which the two thinkers agreed is the divine nature of the human being. This paper compares the approach of the two figures in the issue through discussing and explaining the unity of Being/Reality and the identity of One Being/Reality and human nature. The concept of imago Dei in Ibn Arabi's works and the concept of Self in Vedanta will be debated. In contrast to Shanakra, for Ibn Arabi, the human self is considered as a reality and it has the stronger elements when the human being actualizes the divine attributes, especially knowledge. © 2019, Primrose Hall Publishing Group
Assessment for learning: Espoused and enacted practices of Malaysian teachers
No full textHigh stakes assessment practices have been the most common summative assessments in schools. To address the shortcomings of the summative assessments, Assessment for Learning (AfL) was introduced to provide learners more active feedback and autonomy in their learning progression. In Malaysia, school-based assessments were introduced to reduce the dependency on summative assessments. This paper examines the espoused and the levels of enacted AfL practices of Malaysian Year 7 teachers. A survey and video research design was employed in this study where data were collected from a sample of teachers who taught Mathematics, Science, English Language, and Malay Language. To elicit teachers’ espoused AfL practices, a questionnaire was used while video recordings were utilized as a form of classroom observation to elicit teachers’ enacted AfL practices. The results indicated that there seemed to be agreement among teachers’ espoused AfL practices with AfL strategies for three dimensions which were Sharing Learning Target, Engineering Good Classroom Discussions, and Peer Assessment. The enacted AfL practices of these teachers were predominantly at the lowest levels for all dimensions of AfL practices. This study was not able to establish any relationship between the espoused and enacted AfL practices. It is suggested that both, espoused and enacted AfL practices were be brought to light as foundations for continuous improvement. It is hoped that these results would inform and influence policy makers about the future direction and decision making in improving the quality of school-based assessment implementation. © Universiti Putra Malaysia Press
Carbonic anhydrase IX immunohistochemistry has potential to predict renal cell carcinoma outcomes: A systematic review and meta-analyses
No full textINTRODUCTION: Tissue biomarker carbonic anhydrase IX (CAIX) is purported to have prognostic value for renal cell carcinoma (RCC) but contradicting findings from previous studies have also been documented. This study aims to perform a systematic review and meta-analysis on the role of CAIX in RCC disease progression. MATERIALS AND METHODS: Following the preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines, online searches of multiple databases were performed to retrieve articles from their inception until December 2017. Inclusion criteria included all English-based original articles of immunohistochemistry (IHC) studies investigating CAIX expression in human RCC tissue. Four articles were finally selected for meta-analysis with a total of 1964 patients. Standard meta-analysis methods were applied to evaluate the role of CAIX in RCC prognosis. The relative risk (RR) and its 95% confidence interval (CI) were recorded for the association between biomarker and prognosis, and data were analysed using MedCalc statistical software. RESULTS: The meta-analysis showed that high CAIX expression was associated with low tumour stage (RR 0.90%, 95% CI 0.849-0.969, p= 0.004), low tumour grade (RR 0.835%, 95% CI 0.732-0.983, p= 0.028), absence of nodal involvement (RR 0.814%, 95% CI 0.712-0.931, p= 0.003) and better ECOS-PS index (RR 0.888%, 95% CI 0.818-0.969, p= 0.007). The high tissue CAIX expression in RCC is hence an indication of an early malignancy with a potential to predict favourable disease progression and outcome. CONCLUSION: The measurement of this marker may be beneficial to determine the course of the illness. It is hoped that CAIX can be developed as a specific tissue biomarker for RCC in the near future
Tris-(8-hydroxyquinoline) aluminium thin film as saturable absorber for passively Q-switched erbium-doped fibre laser
No full textA passively Q-switched erbium-doped fibre laser was demonstrated by using tris-(8-hydroxyquinoline)aluminium (Alq3) organic material as a passive saturable absorber (SA). The SA was fabricated by a drop casting technique at room temperature and incorporated into a laser cavity by inserting it between two optical fibre ferrules. The Q-switched fibre laser operates at a centre wavelength of 1559 nm with a full-width half maximum of 1 nm. The generated pulse train is stable and has a pulse width decreased from 6.65 to 1.2 μs and the pulse repetition rate increased from 31.65 to 144.5 kHz as the pump power increased from 20 to 122 mW. The maximum pulse energy obtained is 63.89 nJ. This work indicates that the Alq3 as SA has a great potential to be utilised for pulsed laser generation. To the best of the authors' knowledge, this is the first time an organic material is utilised as a SA device for generating a stable Q-switched laser pulse. © 2019 Institution of Engineering and Technology. All rights reserved
Crosslinked thermoelectric hydro-ionogels: A new class of highly conductive thermoelectric materials
No full textIn this work, a new class of highly-conductive chemically cross-linked gel has been synthesized by the confinement of water and IL N, N, N triethyl octyl ammonium bromide ([N2228] Br) in polyethylene glycol dimethacrylate (PEGDMA) matrix, using in situ thermally initiated radical polymerization loaded with 1 wt% free radical initiator azobisisobutyronitrile (AIBN). This novel gel was named as hydro-ionogel (HIG). The thermoelectric properties of HIG such as ionic conductivity, Seebeck coefficient, and thermal conductivity were measured and owing to its high thermoelectric performance, we referred to this as crosslinked thermoelectric hydro-ionogel, henceforth will be denoted by X-TEHIG. For all the measurements, coin cells were fabricated using commercial LIR 2032 stainless steel battery casings with X-TEHIG sandwiched between the two graphene electrodes. The ionic conductivity of X-TEHIG was examined via AC impedance spectroscopy technique by using a Gamry apparatus. Remarkably, the ionic conductivity of X-TEHIG was higher than that of neat [N2228] Br. A linear increase in ionic conductivity of X-TEHIG as a function of temperature was recorded that showed a considerably higher value of 74 mScm−1 at 70 °C. The origin of this high conductivity is attributed to interactions between PEGDMA monomers and cations and anions of the IL and formation of hydrogen bonds between water and Br− anion, O–H⋯Br−. X-TEHIG demonstrated a higher Seebeck coefficient of 1.38 mVK−1. The Fourier transform infrared (FTIR) spectroscopy results revealed the successful polymerization of X-TEHIG by the disappearance of C[dbnd]C peak of methacrylate group in the spectrum of PEGDMA. These results suggest that X-TEHIG may be a potential candidate for thermoelectric applications owing to their high values of ionic conductivity and Seebeck coefficient. © 2019 Elsevier Lt
Polyacrylonitrile–poly(1‐vinyl pyrrolidone‐co‐vinyl acetate) blend based gel polymer electrolytes incorporated with sodium iodide salt for dye‐sensitized solar cell applications
No full textNew gel polymer electrolytes (GPEs) were prepared via the blending of a polyacrylonitrile polymer and a poly(1-vinyl pyrrolidone-co-vinyl acetate) copolymer. The sodium iodide (NaI) salt concentration was varied for each GPE sample. From ionic conductivity (σ) studies, we observed that the sample with a 40 wt % NaI salt content (N40) showed the highest σ of 3.54 × 10 −3 ± 0.05 S/cm at room temperature, and all of the GPE samples obeyed Arrhenius behavior. The dielectric properties of the GPE samples were also analyzed to study the electrical polarization of the materials. The developed GPE samples were also characterized with X-ray diffraction and Fourier transform infrared spectroscopy. We also then used the developed GPE samples for the fabrication of dye-sensitized solar cells by sandwiching them between a photoanode and Pt counter electrode for photovoltaic studies. The highest photovoltaic performance was achieved by N40, with an efficiency of 3.04%. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47810. © 2019 Wiley Periodicals, Inc
Phrase-based image caption generator with hierarchical LSTM network
No full textAutomatic generation of caption to describe the content of an image has been gaining a lot of research interests recently, where most of the existing works treat the image caption as pure sequential data. Natural language, however possess a temporal hierarchy structure, with complex dependencies between each subsequence. In this paper, we propose a phrase-based image captioning model using a hierarchical Long Short-Term Memory (phi-LSTM) architecture to generate image description. In contrast to the conventional solutions that generate caption in a pure sequential manner, phi-LSTM decodes image caption from phrase to sentence. It consists of a phrase decoder to decode the noun phrases of variable length, and an abbreviated sentence decoder to decode the abbreviated form of the image description. A complete image caption is formed by combining the generated phrases with sentence during the inference stage. Empirically, our proposed model shows a better or competitive result on the Flickr8k, Flickr30k and MS-COCO datasets in comparison to the state-of-the art models. We also show that our proposed model is able to generate more novel captions (not seen in the training data) which are richer in word contents in all these three datasets. © 2018 Elsevier B.V