Penentuan Konstanta A dan K dalam Persamaan Mark-Houwink- Sakurada (MHS) untuk Menentukan Massa Molekul Poli (Asam Laktat) Diol

Poli(asam laktat) diol (PLA-OH) telah disintesis melalui reaksi polimerisasi kondensasi asam laktat dan 1,4-butanadiol. Berat molekul rata-rata (Mn, Mw, dan Mz) PLA-OH ditentukan dengan analisis menggunakan Gel Permeation Chromatography (GPC). Viskositas intrinsiknya diukur pada konsentrasi 0,2 g/dL dan temperatur 298 K menggunakan pelarut kloroform. Melalui metode numerik berhasil ditentukan nilai a dan K dalam persamaan Mark- Houwink-Sakurada untuk PLA-OH, yaitu [η] = 3,532 x 10-4Mv 0,628 = 3,532 x 10-4qMHS 0,628 = 3,415 x 10-4Mw 0,62

Evaluation of mRNA expression levels of cyp51a and mdr1, candidate genes for voriconazole resistance in Aspergillus flavus

Background: Voriconazole Resistance (VRC-R) in Aspergillus flavus isolates impacts the management of aspergillosis, since azoles are the first choice for prophylaxis and therapy. However, to the best of our knowledge, the mechanisms underlying voriconazole resistance are poorly understood. Objectives: The present study was designed to evaluate mRNA expression levels of cyp51A and mdr1 genes in voriconazole resistant A. flavus by a Real-Time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) technique. Materials and Methods: Five A. flavus isolates with resistance to VRC were examined by a RT-PCR approach. Results: Four out of five isolates revealed cyp51A and mdr1 mRNA overexpression. Interestingly, the isolate, which was negative for cyp51A and mdr1 mRNA expression showed a high voriconazole Minimum Inhibitory Concentration (MIC). Furthermore, a computational-based analysis predicted that voriconazole resistance could be mediated through cooperation with a network protein interaction. Conclusions: Our experimental and in silico findings may provide new insight in the complex molecular pathways of drug resistance and also could assist design an efficient therapeutic strategy for aspergillosis treatment. © 2015 Ahvaz Jundishapur University of Medical Sciences

Referencing technique for phase detection in Eddy current evaluation

This paper presents an eddy current testing (ECT) method with a different type of referencing technique for crack detection in carbon steel plate by using two Anisotropic Magnet Resistance (AMR) sensors to detect and evaluate the artificial cracks and to study the output signal's characteristics of each technique. The experiment setup of the magnetic scanning device and the measurement mode is included. Based on these three techniques that have been used, it shown that differential technique with the condition of the required reference signal must be dynamic from one point to one point was the best way to implement in the ECT method. The line scanning results indicate that performing these three techniques can be used to estimate the position of the slits, however, for 2-D mapping, it is shown that the differential technique is a preferable technique where it can remove the noise response, and at the same time, it generates a clear image of the crack. It is predicted that the developed ECT probe using a differential technique can be used as a technique to estimate the characteristic of defects in a metal plate

A low-frequency Eddy current probe based on miniature fluxgate array for defect evaluation in steel components

Detecting defects in high-permeability steel components can be challenging when using the eddy current technique. This is due to the strong magnetization signal that is simultaneously generated along with the eddy current signal. To minimize the regions of the induced eddy current and its detection, an eddy current probe based on an array of miniature fluxgate sensors (DRV425; Texas Instrument, USA) and axial inductors was proposed and fabricated in the study. The fluxgate sensors were arranged in two layers, and the sensors were sandwiched between two layers of inductors. The output signals from the fluxgate array were sampled to obtain a differential signal of the eddy current intensity and direction. A phase-sensitive detection technique was implemented to isolate the strong magnetization signal from the detected eddy current signal and utilized to characterize artificial slits with varying depths. The developed probe successfully characterized both the vertically and horizontally oriented slits with depths from 2 to 10 mm on a 12 mm-thick mild steel plate. A better sensitivity was notable in the evaluation of the vertical slits where the vertical slits would increase the eddy current intensity in contrast to the horizontal slits around the slits. It was shown that the eddy current’s distribution map obtained from the developed probe could be used to reveal the physical dimension of the slit

Extraction of flux leakage and eddy current signals induced by submillimeter backside slits on carbon steel plate using a low-field amr differential magnetic probe

Magnetic Flux Leakage (MFL) and Eddy Current Testing (ECT) are commonly employed as the non-destructive evaluation (NDE) techniques used to detect defects within the steel. The MFL technique is advantageous in terms of deep defects detection, while the ECT technique excels in providing dense information regarding defects. In this work, artificial MFL and eddy current (EC) signals in ferromagnetic materials are studied, and an experimental magnetic probe that utilizes both techniques is developed for signal verification. The separation between MFL and EC signals is achieved by utilizing the phase-sensitive detection technique, implementing a dynamic referencing method as opposed to the conventional static phase referencing. A finite element method (FEM) based simulation is employed to study and verify the MFL and EC signals measured by the proposed magnetic probe. The proposed magnetic probe features highly sensitive anisotropic magneto-resistive sensors capable of measuring the MFL and EC signals induced by artificial slits of varying depths engraved onto a 2-mm carbon steel plate. Finite element simulations indicate different flux leakage patterns and eddy current signals detected in the vicinity of the back-side slits. A good agreement is observed between the simulated and the measured MFL and EC signals for the optimized frequency range of 110-210 Hz with the corresponding Lissajous curve for the detection of submillimeter back-side slits. The study has shown that the combination of MFL and EC signals can be successfully captured by an appropriate magnetic probe for an enhanced detection performance of back-side defects in ferromagnetic materials

Evaluation of back-side slits with sub-millimeter resolution using a differential AMR probe

The electromagnetic method of the Non-destructive Test is one of the approaches in the field of crack detection on a metallic sample. One of the techniques that appear in the electromagnetic method is the Eddy Current Testing (ECT), where it utilizes the electromagnetic principle to detect cracks in metallic components. In this research, an ECT probe that is made up of two AMR sensors, two excitation coils, and a developed set/reset circuit. Besides, a digital lock-in amplifier has also been developed by using NI-LabVIEW and a data acquisition (DAQ) card. A measurement system that incorporates the ECT probe and the digital lock-in amplifier as well as an amplifier circuit, a power supply, a PC and an XY stage to which the probe is attached to, is developed. Then, artificial slits with different depths from 768 µm to 929 µm are created on a galvanized steel plate sample. The slits are evaluated from the back-side of the galvanized steel plate via two types of scanning, which is the line scan and full map scanning. From the results of the line scan, the localization of the slits, as well as their depths, could be performed and estimated. Furthermore, 2-D mapping of the sample from the backside has been generated. The 2-D map shows that the position of the slits could be estimated, including their slits depths

Biting flies and trypanosomiasis in Sahom livestock farm: ‘The Missing Link’

Trypanosomiasis positive cases were reported in Sahom Farm Retreat in Gopeng, Perak; with multispecies livestock animals. Nzi and Vavoua traps were applied to survey the population of biting flies; stable flies (Muscidae: Stomoxyinae) and horse flies (Tabanidae) as the vector for surra. Results indicated the presence of Trypanosomiasis infection diagnosed by buffy coat examination, thin blood stained smears and serological test (Surra Sero K-Set test) and identification of its insect vectors. The presence of both biting flies provides the missing link between the occurrence of the disease and host or environmental factors precipitating the disease. Besides trypanosomiasis in cattle, other parasitic infections were also recorded with heavy infections for liver fluke (Fasciola gigantica ova) and coccidia oocysts. Therefore, some control measures are recommended to eradicate the vectors and to treat infected animals in order to prevent the dissemination of the trypanosmiasis