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Membrane-based approach for the removal of pigment impurities secreted by Pichia pastoris
(2023-05-01)
Kongsinkaew, Chatchol
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Ajariyakhajorn, Kittisak
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Boonyaratanakornkit, Viroj
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Sooksai, Sarintip
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Pornpukdeewattana, Soisuda
During recombinant protein expression in Pichia pastoris under the alcohol oxidase promoter, the culture supernatant developed green and yellow pigments, complicating downstream processing. Currently, a chromatography-based purification approach is one of the most efficient strategies to eliminate these pigments, but this method is complicated and often the most expensive step during processing. In this study, we designed a sequential cross-flow filtration by the combination of a microfiltration membrane with a pore size of 0.2 micrometers, followed by an ultrafiltration membrane with a molecular weight cut-off of 10 and 2 kilodaltons (kDa), respectively, and finished with diafiltration of the 10 and 2 kDa retentate fractions. The results show that the microfiltration membrane eliminated host cell impurities and significantly reduced the green pigment, which was measured using the 1976 CIE LAB system, while the 10 and 2 kDa membranes allowed the yellow pigment to pass through. The diafiltration steps also significantly reduced the yellow pigment. The host cell proteins were removed by recirculating in the retentate fraction of the 10 kDa membrane, while the 4.1 kDa target peptide, the candidate cell-penetrating antimicrobial peptide, was recovered by recirculation in the retentate fraction of the 2 kDa membrane.
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Fabrication of Contour Cavity Using Multi-Exposure Lithography for MEMS Capacitive Microphone
(2018-07-02)
Jantawong, Jirawat
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Atthi, Nithi
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Leepattarapongpan, Chana
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Jeamsaksiri, Wutthinan
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Austin, Anu
This paper presents a novel technique to optimize a capacitive pressure sensor with multi-exposure dose lithography. As part of achieving high signal to noise ratio (SNR) in microphone, a new design was implemented. The new design defies the conventional wisdom of parallel plate theory and implement a concept of contour cavity (backplate) to follows the diaphragm deflection. This 3-dimensional contour cavity (CC) is fabricated by multi-exposure dose lithography with single silicon etching process. The CC structure with different etched depth of 0.65, 1.15, and 1.57 micron were fabricated by multi-exposure dose of 92, 120, and 210 mJ/cm<sup>2</sup>on 5.0 micron thick photoresist and single step etching with CF<inf>4</inf>/O<inf>2</inf>plasma (Si/PR etch selectivity: 1.3). Due to this novel contour cavity design, polysilicon membrane with 0.8 micron thick and a diameter of 930 micron structure produces the capacitance value of 2.88 pF, which is 28.6% higher than that of conventional parallel plate capacitive sensor.
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Synthesis of carbon nanotube and carbon nanofiber in nanopore of anodic aluminum oxide template by chemical vapor deposition at atmospheric pressure
(2012-10-15)
Kasi, Jafar Khan
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Kasi, Ajab Khan
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Wongwiriyapan, Winadda
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Afzulpurkar, Nitin
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Dulyaseree, Paweena
Carbon nanotube (CNT) is one of the most attractive materials for the potential applications of nanotechnology due to its excellent mechanical, thermal, electrical and optical properties. We demonstrated the fabrication of carbon nanotube and carbon nanofiber (CNF) inside the pore and at the surface of anodic aluminum oxide (AAO) membrane by chemical vapor deposition method at atmospheric pressure. Ethanol was used as a hydrocarbon source and Co-Mo as catalyst. CNT was synthesized at different temperature. High graphitic multiwall carbon nanotube (MWCNT) was found at 750°C, while CNF was found at 800oC and above temperature analyzing by Raman spectroscopy. © (2012) Trans Tech Publications, switzerland.
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Fabrications of three dimensional anodic aluminum oxide micro shapes
(2012-05-01)
Kasi, Jafar Khan
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Kasi, Ajab Khan
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Afzulpurkar, Nitin
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Hasan, Mahadi
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Pratontep, Sirapat
Anodic aluminum oxide (AAO) is one of attractive materials which are used for the fabrication of micro and nanostructures. This paper describes the fabrication of three dimensional (3D) microstructures with AAO nano porous membrane. A simple procedure has been adopted to develop microstructures using the same aluminum (Al) sample without any assistance of scaffold or molding process. Various shapes including micro conical tube, micro cone, and micro bowl structures have been fabricated. Those factors have also been analyzed which are affecting the shapes of microstructures like cracks, angle, and geometry. The fabricated 3D shapes have potential applications in drug delivery system. © 2012 American Scientific Publishers.
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Determination of membrane resistance for cross-flow microfiltration in a rectangular module including back-flow
(2008-01-01)
Wattananusorn, Santi
In the current note, the previously developed semiempirical models are incorporated, based on blocking filtration laws, with an approach by using a higher-order pressure function over the membrane surface providing the local non-linear characteristic of the transmembrane pressure during discontinuous semibatch processes. Consequently, the flux predictions of a continuous cross-flow microfiltration system with back-flow across a membrane module are appropriately modified for more accurate formulations of membrane resistance. © IMechE 2008.
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Automation Reverse Osmosis System using Computer Analyze
(2003-10-01)
Tipsuwanpom, V.
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Anotaiadikoon, J.
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Gulpanich, S.
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Krongratana, V.
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Witheephanich, K.
As Pure & Drinking water system is universally employed in Industrial,Reverse Osmosis System (ROS) has been becoming increasingly popular due to efficiency in Salt & Organic Rejection of it. However membrane system need regular cleaning. This paper present a new method for automation cleaning Reverse Osmosis System using Computer monitoring Process & analyze Trend of membrane performance & discuss enter to automation cleaning. The membrane performance consist of TDS, Water Flow, Pressure and Temperature. These variable analyzed for automation cleaning in order to maintain productivity and performance of RO System.

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