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Alignment precision of polarization components
(2019-12-20)
Hagen, Nathan
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Buranasiri, Prathan
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Otani, Yukitoshi
Recent research publications in the polarization literature have discussed methods of correcting for azimuthal alignment errors of optical elements in postprocessing. However, we show that high angular precision is not difficult to achieve during system alignment, so that postprocessing correction should be unnecessary. We estimate the alignment precision achievable for linear polarizers and waveplates in polarization systems. This shows that using an optical signal model for alignment allows a precision limited by the quality of the optics and detectors rather than the quality of the mechanics, rendering millidegree alignment precision possible with ordinary rotational mounts.
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Low-voltage low-pass and band-pass elliptic filters based on log-domain approach suitable for biosensors
(2019-12-02)
Prommee, Pipat
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Wongprommoon, Natapong
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Kumngern, Montree
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Jaikla, Winai
This research proposes bipolar junction transistor (BJT)-based log-domain high-order elliptic ladder low-pass (LPF) and band-pass filters (BPF) using a lossless differentiator and lossless and lossy integrators. The log-domain lossless differentiator was realized by using seven BJTs and one grounded capacitor, the lossy integrator using five BJTs and one grounded capacitor, and the lossless integrator using seven BJTs and one grounded capacitor. The simplified signal flow graph (SFG) of the elliptic ladder LPF consisted of two lossy integrators, one lossless integrator, and one lossless differentiator, while that of the elliptic ladder BPF contained two lossy integrators, five lossless integrators, and one lossless differentiator. Log-domain cells were directly incorporated into the simplified SFGs. Simulations were carried out using PSpice with transistor array HFA3127. The proposed filters are operable in a low-voltage environment and are suitable for mobile equipment and further integration. The log-domain principle enables the frequency responses of the filters to be electronically tunable between 10k Hz–10 MHz. The proposed filters are applicable for low-frequency biosensors by reconfiguring certain capacitors. The filters can efficiently remove low-frequency noise and random noise in the electrocardiogram (ECG) signal.
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Locating an ambulance base by using social media: a case study in Bangkok
(2019-12-01)
Nilsang, Suriyaphong
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Yuangyai, Chumpol
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Cheng, Chen Yang
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Janjarassuk, Udom
Response time reduction is a fundamental aspect of ambulance location management. To minimize patient mortality and disability, the response time of emergency medical services is critical. Therefore, real-time management is required to determine the location of an ambulance with a low response time or called or a dynamic allocation system. Dynamic allocation is moving the ambulance bases from low demand areas to high-demand areas that is useful in the operational level. However, the dynamic allocation model for real-time management requires re-allocation of ambulances, resulting in high costs and heavy workloads for the ambulance crews. This paper focuses on a covering model based on social media analysis. The model was used for developing an ambulance reallocation system. In addition to dynamic allocation, the proposed model considers real-time data from a social media application (Twitter) to minimize the response time and cost during emergencies and disasters. Twitter has been used in various ways to communicate during and manage emergencies. In this paper, we formulate the Maximal Covering Location Problem (MCLP), develop a solution procedure based on social media (Twitter application) and show the effect of the approach on the optimal solution by comparing it with the classical approach and also demonstrate our approach on Bangkok EMS.
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Influence of hydrothermal time on structural properties of ZnO nanorods grown on spin-coated ZnO seeding layer
(2019-12-16)
Mahamu, Hambalee
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Srinonate, Wuttichai
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Pecharapa, Wisanu
Most of the recent nanodevices are fabricated by using high-efficiency deposition methods and patterned via high-resolution lithography. However, there are drawbacks for the methods including small-scale product, high cost consumption, and multi-step processes. To reduce these disadvantages, this work focuses on the usage of sol-gel synthesis and spin coating method to fabricate ZnO seed layer onto glass substrates. All of substrates were patterned by conventional UV photolithography at exposure time of 7 seconds, then ZnO nanorods were hydrothermally grown at 90°C for 2, 3, and 4 hours, respectively. All of samples were characterised by scanning electron microscope (SEM) which revealed the sharp and smooth tip hexagonal structure at different hydrothermal time. The evolution of the nanorods' growth was investigated, and the diameters were estimated. Moreover, crystal quality was revealed by X-ray diffractograms. It was clear that the domination of c-axis plane occurred for all the samples associates with the crystallinity of the nanostructures. This indicated escalating of the non-monodirectional growth plane in increasing nanorods' diameter as the nanorods are polycrystal. Furthermore, the optical properties of the samples were observed by UV-visible spectroscopy and photoluminescence technique (PL). UV-visible spectroscopic data showed diminishing of the energy band gap when the diameter grew up. PL data revealed the reduction of the intensity ratio at near-band-edge peak versus oxygen vacancy peak. This information pointed to the decreasing trend of the crystal quality with escalating growth time.
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Herbicidal Activity of Flavokawains and Related trans-Chalcones against Amaranthus tricolor L. And Echinochloa crus-galli (L.) Beauv.
(2019-12-10)
Chotsaeng, Nawasit
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Laosinwattana, Chamroon
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Charoenying, Patchanee
Flavokawains have a broad spectrum of biological activities; however, the herbicidal activity of these naturally occurring chalcones has been less investigated. Flavokawains and their analogues were prepared by the Claisen-Schmidt condensation reaction between xanthoxyline (or aromatic ketones) and a variety of aromatic and heteroaromatic aldehydes. These compounds were then evaluated for their inhibitory effect against representative dicot and monocot plants. Among 45 synthetic chalcones, derivatives containing phenoxyacetic acid, 4-(N,N-dimethylamino)phenyl, N-methylpyrrole, or thiophenyl groups inhibited the germination and growth of Chinese amaranth (Amaranthus tricolor L.) with moderate to high degrees compared to commercial butachlor. For barnyardgrass (Echinochloa crus-galli (L.) Beauv.), most of the thiophenyl chalcones interrupted shoot and root emergence. This finding highlighted the importance of functional groups on the herbicidal activity of chalcones. The level of inhibition also depended on the applied concentrations, plant species, and plant organs. (E)-2-(2-(3-Oxo-3-(thiophen-2-yl)prop-1-enyl)phenoxy)acetic acid (14f) was the most active compound among 45 derivatives. This chalcone could be a promising structure for controlling the germination and growth of weeds. The structure-activity relationship results provide useful information about the development of active chalconoids as novel natural product-like herbicides.
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Efficacy of nanodiamond–doxorubicin complexes on human breast adenocarcinoma cell lines
(2019-12-04)
Locharoenrat, Kitsakorn
This paper aims to demonstrate the efficacy of the immobilisation of the chemotherapy drug doxorubicin on nanodiamond platforms as a potential cancer therapy. This effective drug is experimentally fed into a human breast adenocarcinoma cell lines. Drug loading activity and cell viability are detected by spectrometer, microscopy, and MTT assay in this study at Biomedical Physics Research Unit, Department of Physics, Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand between 1 Oct 2018 and 10 Jun 2019. Experimental results show that in the basic environment (pH = 8.0), the nanodiamond carboxylic group cooperated with the doxorubicin amino group to form a stable and non-covalent bond on nanodiamond surfaces served as a simple physical adsorption. In an acidic environment suitable to targeting the cancer cells, the nanodiamond carboxylic group ionised so that doxorubicin is effectively released. Doxorubicin therefore affirmatively absorbed into the cytoplasm and later into the nucleus. The significant finding of the study is that IC-50 equivalent to 0.40 mg/mL and viable nanodiamond–doxorubicin is a good candidate material for drug delivery.
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Impact of Engine Oil Additives on Nanostructure and Oxidation Kinetics of Diesel and Synthetic Biodiesel Particulate Matters using Electron Microscopy
(2019-12-19)
Koko, Phyozin
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Karin, Preechar
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Charoenphonphanich, Chinda
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Chollacoop, Nuwong
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Hanamura, Katsunori
Physicochemical characteristics of particulate matters which are influenced by engine oil additives from engine combustion of diesel and synthetic biodiesel: Hydrotreated vegetable oil (HVO) were successfully investigated using electron microscopy, electron dispersive X-ray spectroscopy and thermogravimetric analysis. The agglomerate structure of diesel PM, HVO PM and diesel blending lubricant PM are similar in micro-scales. However, nanostructure of soot is a spherical shape composed of curve line crystallites while the metal oxide ash nanostructure is composed of parallel straight line hatch patterns. The oxidation kinetics of fuel blending lubricant PMs are higher than neat fuel PMs due to catalytic effect of incombustible metal additives from engine lubricating oil.
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Optimal control of the dengue dynamical transmission with vertical transmission
(2019-12-01)
Pongsumpun, Puntani
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Tang, I. Ming
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Wongvanich, Napasool
Dengue disease is found in tropical and subtropical regions around the world. Dengue virus is the cause of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. It consists of 4 serotypes: DEN-1, DEN-2, DEN-3, and DEN-4. There are two modes of transmission for dengue virus in mosquito: horizontal transmission and vertical transmission. The mosquito can be infected when it bites an infectious human by horizontal transmission, but there can also be vertical transmission through sexual contact with an infected mosquito. This research presents a control mechanism based on our previously developed dengue model with vertical transmission. The two policies, namely vaccination and insecticide administration (Policy 1) and isolation and insecticide administration (Policy 2) are considered. The use of Pontryargin’s maximum principle allowed necessary and optimality conditions, thus facilitating the optimal control to be developed. Numerical solutions of our control systems and the conclusions of our two policies are presented.
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Solving systems of nonhomogeneous coupled linear matrix differential equations in terms of Mittag-Leffler matrix functions
(2019-12-01)
Kongyaksee, Rungpailin
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Chansangiam, Pattrawut
In this paper, we investigate systems of nonhomogeneous coupled linear matrix differential equations. Applying Kronecker products, the vector operator, and matrix convolution product, we obtain explicit formula of the general solution to this system in terms of matrix series concerning exponentials and Mittag-Leffler functions.
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Graphene nanosheet-grafted double-walled carbon nanotube hybrid nanostructures by two-step chemical vapor deposition and their application for ethanol detection
(2019-12-01)
Muangrat, Worawut
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Wongwiriyapan, Winadda
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Morimoto, Shingo
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Hashimoto, Yoshio
Here, we present a facile technique for synthesis of graphene nanosheet (GNS)-grafted double-walled carbon nanotube (DWCNT) hybrid carbon nanostructures (here after referred to as G-DWCNTs) by directly growing GNSs along the sidewalls of DWCNTs using a two-step chemical vapor deposition (CVD). DWCNTs were synthesized by floating catalyst CVD at 1300 °C using ferrocene and thiophene dissolved in ethanol. Then, GNSs were grafted onto the synthesized DWCNT bundles by thermal CVD at 1300 °C using ethanol. The sharp-edged petal-like structure of GNSs were grown along the sidewalls of DWCNT bundles while maintaining the one-dimensional structure of DWCNT. Next, DWCNTs and G-DWCNTs were dispersed in ethanol, then deposited on the paper using vacuum filtration method and used for ethanol detection. G-DWCNTs sensor exhibited a 3-fold improvement in the response to ethanol vapor compared to the DWCNTs sensor. The sensing mechanism of DWCNTs and G-DWCNTs can be described in terms of charge transfer between the gas molecules and sensing material. These results demonstrate that the facile technique by two-step CVD method provides a promising approach for simple and low-cost technique to synthesize the hybrid nanostructure of GNSs and DWCNTs. The new hybrid carbon nanostructures are attractive for gas sensing application.

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