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Maneewan S.,Buriram Rajabhat University | Sreewirote B.,Thonburi University | Jaikla W.,Suan Sunandha Rajabhat University
Proceedings of 2011 IEEE International Conference on Vehicular Electronics and Safety, ICVES 2011 | Year: 2011

A current-mode quadrature oscillator using single current follower transconductance amplifier (CFTA) as active element is given. The oscillator has high output impedance, employs two grounded capacitors, single resistor and has electronic control on oscillation condition and on oscillation frequency. The proposed circuit is suitable for integrated circuit (IC) architecture. PSpice simulation result is included to demonstrate the practicality of the oscillator circuit. © 2011 IEEE.


Siriphot D.,Buriram Rajabhat University | Maneewan S.,Buriram Rajabhat University | Jaikla W.,King Mongkut's University of Technology Thonburi
BMEiCON 2013 - 6th Biomedical Engineering International Conference | Year: 2013

This article presents grounded inductance simulator using single current controlled current follower transconductance amplifier (CCCFTA) as active element. The simulated inductance value can be controlled electronically by adjusting the bias current of the CCCFTA. The grounded inductance simulator comprises one CCCFTA and one grounded capacitor without any external resistors and component matching requirements. The circuit performances are depicted through PSpice simulations, they show good agreement to theoretical anticipation. An application as second-order low-pass filter is included to confirm the usability of proposed circuit. It is very suitable to realize the proposed filter in monolithic chip to use in biomedical signal processing. © 2013 IEEE.


Pourak T.,King Mongkut's University of Technology Thonburi | Suwanjan P.,King Mongkut's University of Technology Thonburi | Jaikla W.,King Mongkut's University of Technology Thonburi | Maneewan S.,Buriram Rajabhat University
2012 IEEE International Conference on Electron Devices and Solid State Circuit, EDSSC 2012 | Year: 2012

The voltage-mode quadrature sinusoidal oscillator using single voltage differencing tranconductance amplifier (VDTA) and grounded elements is presented. The proposed oscillator can provide 2 sinusoidal output voltages with 90° phase difference. The condition of oscillation (CO) and frequency of oscillation can be electronically/orthogonally controlled by adjusting the bias current of the VDTA. The use of only grounded elements is ideal for integration. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation. © 2012 IEEE.


Maneewan S.,Buriram Rajabhat University | Udorn N.,Nakhon Phanom University | Duangmalai D.,Nakhon Phanom University | Silapan P.,Uttaradit Rajabhat University | Jaikla W.,King Mongkut's University of Technology Thonburi
Advances in Electrical and Electronic Engineering | Year: 2014

This article presents a new voltage-mode first order allpass filter (APF) employing voltage differencing transconductance amplifier (VDTA). The advantages of the circuit are that: the circuit description is very compact, consists of merely a VDTA and a capacitor: the phase shift can be electronically adjusted by current bias: it provides the lower THD of the output signal. Without any component matching conditions, the proposed circuit is very appropriate to further develop into an integrated circuit. Moreover, the proposed APF can provide the output current with high output impedance without modification of the circuit topology. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation. The maximum power consumption is 400μ W at ±1.25V power supplies. © 2014 Advances in electrical and electronic engineering.


Iamarejin A.,King Mongkut's University of Technology Thonburi | Maneewan S.,Buriram Rajabhat University | Suwanjan P.,King Mongkut's University of Technology Thonburi | Jaikla W.,King Mongkut's University of Technology Thonburi
Przeglad Elektrotechniczny | Year: 2013

In this study, a current-mode first order allpass filter using current follower transconductance amplifiers (CFTAs) is proposed. The features of the circuit are that: the pole frequency, phase response and current gain can be electronically controlled via the input bias current: the circuit description is very simple, consisting of 2 CFTAs, 1 resistor and 1 grounded capacitor, without any component matching requirements. Consequently, the proposed circuit is very appropriate to further develop into an integrated circuit. Low input and high output impedances of the proposed configuration enable the circuit to be cascaded in current-mode without additional current buffers. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation.


Uthitsunthorn D.,Buriram Rajabhat University | Kulworawanichpong T.,Suranaree University of Technology
Asia-Pacific Power and Energy Engineering Conference, APPEEC | Year: 2012

This paper presents a conceptual design of multi-agent for adaptive over-current relay coordination. In some temporary circumstances e.g. line outage, connecting a new or existing generator, etc., may lead to mal-operation of pre-coordinated protective devices in power systems. The set of protective relays must be enhanced with ability of adaptation in such a way that their parameter setting is adjusted. The multi-agent system proposed here is to develop optimal relay coordination adaptively according to environment changes. In this paper, Java Agent Development (JADE) software package was used for implementing the proposed multi-agent system. The communication process and data transfer can be simulated and monitored by using the sniffer agent GUI that helps us to confirm the use of multi-agent systems for an application of adaptive relay coordination. The 6-bus test power system was used for test. The results showed that the use of the multi-agent system is very useful in adaptive over-current relay coordination. © 2012 IEEE.


Promden W.,Buriram Rajabhat University | Promden W.,Chulalongkorn University | Monthakantirat O.,Khon Kaen University | Umehara K.,University of Shizuoka | And 2 more authors.
Molecules | Year: 2014

The antioxidant activities of 24 isoflavonoids that were previously isolated as pure compounds from Dalbergia parviflora were evaluated using three different in vitro antioxidant-based assay systems: xanthine/xanthine oxidase (X/XO), ORAC, and DPPH. The isolates consisted of three subgroups, namely isoflavones, isoflavanones, and isoflavans, each of which appeared to have diversified substituents, and were thus ideal for the study of their structure-activity relationships (SARs). The SAR analysis was performed using the results obtained from both the inter-subgroup isoflavonoids with the same substitution pattern and the intra-subgroup compounds with different substitution patterns. The inter-subgroup comparison showed that the isoflavones exhibited the highest antioxidant activities based on all three assays. The intra-subgroup analysis showed that the additional presence of an OH group in Ring B at either R3′ or R5′ from the basic common structure of the R7-OH of Ring A and the R4′-OH (or -OMe) of Ring B greatly increased the antioxidant activities of all of the isoflavonoid subgroups and that other positions of OH and OMe substitutions exerted different effects on the activities depending on the subgroup and assay type. Therefore, based on the structural diversity of the isoflavonoids in D. parviflora, the present study provides the first clarification of the detailed antioxidant SARs of isoflavonoids. © 2014 by the authors; licensee MDPI, Basel, Switzerland.


PubMed | Chulalongkorn University, University of Shizuoka, Buriram Rajabhat University and Khon Kaen University
Type: Journal Article | Journal: Molecules (Basel, Switzerland) | Year: 2014

The antioxidant activities of 24 isoflavonoids that were previously isolated as pure compounds from Dalbergia parviflora were evaluated using three different in vitro antioxidant-based assay systems: xanthine/xanthine oxidase (X/XO), ORAC, and DPPH. The isolates consisted of three subgroups, namely isoflavones, isoflavanones, and isoflavans, each of which appeared to have diversified substituents, and were thus ideal for the study of their structure-activity relationships (SARs). The SAR analysis was performed using the results obtained from both the inter-subgroup isoflavonoids with the same substitution pattern and the intra-subgroup compounds with different substitution patterns. The inter-subgroup comparison showed that the isoflavones exhibited the highest antioxidant activities based on all three assays. The intra-subgroup analysis showed that the additional presence of an OH group in Ring B at either R3 or R5 from the basic common structure of the R7-OH of Ring A and the R4-OH (or -OMe) of Ring B greatly increased the antioxidant activities of all of the isoflavonoid subgroups and that other positions of OH and OMe substitutions exerted different effects on the activities depending on the subgroup and assay type. Therefore, based on the structural diversity of the isoflavonoids in D. parviflora, the present study provides the first clarification of the detailed antioxidant SARs of isoflavonoids.


PubMed | Chulalongkorn University, Buriram Rajabhat University and Srinakharinwirot University
Type: | Journal: Phytochemistry | Year: 2015

While attempting to isolate the enzyme geranylgeraniol 18-hydroxylase, which is involved in plaunotol biosynthesis in Croton stellatopilosus (Cs), the cDNAs for a cytochrome P450 monooxygenase(designated as CYP76F45) and an NADPH-cytochrome P450 reductase (designated as CPR I based on its classification) were isolated from the leaf. The CYP76F45 and CsCPR I genes have open reading frames (ORFs) encoding 507- and 711-amino acid proteins with predicted relative molecular weights of 56.7 and 79.0 kDa,respectively. Amino acid sequence comparison showed that both CYP76F45 (6373%) and CsCPR I (7983%) share relatively high sequence identities with homologous proteins in other plant species.Phylogenetic tree analysis confirmed that CYP76F45 belongs to the CYP76 family and that CsCPR I belongs to Class I of dicotyledonous CPRs, with both being closely related to Ricinus communis genes. Functional characterization of both enzymes, each expressed separately in Escherichia coli as recombinant proteins,showed that only simultaneous incubation of the membrane bound proteins with the substrate geraniol (GOH) and the coenzyme NADPH could form 8-hydroxygeraniol. The enzyme mixture could also utilize acyclic sesquiterpene farnesol (FOH) with a comparable substrate preference ratio (GOH:FOH) of 54:46. The levelsof the CYP76F45 and CsCPR I transcripts in the shoots, leaves and twigs of C. stellatopilosus were correlated with the levels of a major monoterpenoid indole alkaloid, identified tentatively as 19-Evallesamine,that accumulated in these plant parts. These results suggested that CYP76F45 and CPR I function as the enzyme geraniol-8-hydroxylase (G8H), which is likely to be involved in the biosynthesis of the indole alkaloid in C. stellatopilosus [corrected].


PubMed | Naresuan University, Buriram Rajabhat University and Khon Kaen University
Type: Journal Article | Journal: Environmental science and pollution research international | Year: 2016

Cadmium (Cd) has known to produce many adverse effects on organs including placenta. Many essential transporters are involved in Cd transport pathways such as DMT-1, ZIP as well as L-VDCC. Fourteen pregnant women participated and were divided into two groups: high and low Cd-exposed (H-Cd, L-Cd) groups on the basis of their residential areas, Cd concentrations in the blood (B-Cd), urine (U-Cd), and placenta (P-Cd). The results showed that the B-Cd and U-Cd were significantly increased in H-Cd group (p<0.05). Interestingly, the P-Cd in H-Cd group was elevated (p<0.05) and positively related to their B-Cd and U-Cd values (p<0.05). However, the mean cord blood Cd (C-Cd) concentration in H-Cd group was not significantly increased about 2.5-fold when comparing to L-Cd group. To determine the Cd accumulation in placental tissues, metallothionein-1A (MT-1A) and metallothionein-2A (MT-2A) expressions were used as biomarkers. The results revealed that mean MT-1A and MT-2A mRNAs and MT-1/2 proteins were up-regulated in H-Cd group (p<0.05). In addition, the Ca channel alpha 1C (CACNA1C) mRNA and protein expressions were noticeably elevated in H-Cd group (p<0.05). From these findings, we suggested that CACNA1C might be implicated in Cd transport in human placenta.

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