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REAL-TIME MEASUREMENT OF ICE CONCENTRATIONS IN ICE SLURRY FLOW
Peck, Jong-Hyeon,Hong, Hi-Ki,Kang, Chae-Dong The Society of Air-Conditioning and Refrigerating 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.2
An experimental study was performed to measure the ice concentration of an ice slurry pipe flow in real time. In the present work, we suggest a refractive index measurement method and compare it to freezing point and density measurement methods. To measure the refractive index of the solution, ice particles in the ice slurry should be completely removed and a hydro-cyclone was used in this study instead of a mesh. The results from the measurement method by the refractive index coincided with those by the density within a ${\pm}$5% error range when the real-time solution density was used. Even though the density measurement method showed good resolution, the results using the initial density of the solution were more than 10% in error compared to those using the real-time density. And the density measurement method has an error range 1.5 times greater than the refractive index measurement method.
Peck Loo Kiew,Zainal Ahmad,Mashitah Mat Don 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.2
Fractional factorial design (FFD) was applied to evaluate the effects of various process parameters in influencing the extraction efficiency of pepsin soluble collagen (PSC) from muscles of cultured catfish (Clarias gariepinus×C. macrocephalus). Result of the first order factorial design showed that acetic acid concentration, acid extraction time, acetic acid to muscles ratio, and stirring speed posed significant effect (P<0.05) on the yield of PSC obtained at the end of the extraction process. Two different artificial intelligence techniques namely artificial neural network (ANN) and genetic algorithm (GA) were then integrated for optimizing the extraction conditions to obtain the highest yield of PSC. The ANN was trained using the back propagation algorithm. A model was successfully generated with R2 value of 0.9527 and MSE value of 0.1672 for unseen data set, implying a good generalization of the network. Input parameters of the established ANN model were subsequently optimized using GA. The hybrid of ANN-GA model predicted a maximum extraction yield of PSC at 238.25 mg/g under the following conditions: an acetic acid concentration of 0.70 M, the acetic acid to muscles ratio of 25.78 mL/g,and the stirring speed of 432.50 rpm. Verification of the optimization showed the percentage error differences between the experimental and predicted values were less than 5%, indicating excellent modeling, predicting ability and optimization by the ANN-GA model.
Composite Membrane Containing a Proton Conductive Oxide for Direct Methanol Fuel Cell
Peck, Dong-Hyun,Cho, Sung-Yong,Kim, Sang-Kyung,Jung, Doo-Hwan,Kim, Jeong-Soo The Korean Electrochemical Society 2008 한국전기화학회지 Vol.11 No.1
The composite membrane for direct methanol fuel cell (DMFC) was developed using $H_3O^+-{\beta}"-Al_2O_3$ powder and perfluorosulfonylfluroride copolymer (Nafion) resin. The perfluorosulfonylfluroride copolymer (Nafion) resin was mixed with $H_3O^+-{\beta}"-Al_2O_3$ powder and it was made to sheet form by hot pressing. The electrodes were prepared with 60 wt% PtRu/C and 60wt% Pt/C catalysts for anode and cathode, respectively. The morphology and the chemical composition of the composite membrane have been investigated by using SEM and EDXA, respectively. The composite membrane and $H_3O^+-{\beta}"-Al_2O_3$ were analyzed by using FT-IR and XRD. The methanol permeability of the composite membranes was also measured by gas chromatography (GC). The performance of the MEA containing the composite membrane (2wt% $H_3O^+-{\beta}"-Al_2O_3$) was higher than that of normal pure Nafion membrane at high operating temperature (e.g. $110^{\circ}C$), due to the homogenous distribution of $H_3O^+-{\beta}"-Al_2O_3$, which decreased the methanol permeability through the membrane and enhanced the water contents in the composite membrane.
MEASUREMENT OF ICE PACKING FACTOR OF AQUEOUS SOLUTION WITH ICE SLURRY USING REFRACTIVE INDEX
Peck, Jong-Hyeon,Kang, Chae-Dong,Hong, Hi-Ki The Society of Air-Conditioning and Refrigerating 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.2
In the present work, a new method is proposed for the measurement of the ice packing factor (IPF) of an ice slurry using the index of refraction. The purpose of the new method is to improve the resolution of the measurement and to increase its resistance to electric noise as compared to the standard IPF measurement technique that relies on the measurement of the freezing temperature. These two methods are similar in that they both obtain a concentration of aqueous solution from the measured physical quantities and calculate the IPF using the relationship between concentration and IPF. Both methods were also compared with the results from the calorimeter method obtaining the IPF directly. The two methods are in good agreement (within 5%), which demonstrate the validity of the newly proposed method.
Isolation and Characterization of Collagen from the Skin of Malaysian catfish (Hybrid Clarias sp.)
Peck Loo Kiew,Mat Don Mashitah 한국응용생명화학회 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.4
Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were isolated from the skin of hybrid Clarias sp. with the yields of 18.11±0.32 and 26.69±0.54% (wet weight basis), respectively. Both collagens were characterized as type I collagen, containing α1 and α2 chains. Presence of high molecular weight crosslinks were observed in the gel electrophoresis of both collagens. Fourier transform infrared spectra of both collagens were almost similar, suggesting that pepsin hydrolysis did not disrupt the triple helical structure. The amino acid analysis showed glycine was the most abundant, with 207/1000 and 223/1000 residues present in ASC and PSC, respectively. The amounts of imino acids were 185/1000 residues for both. Thermal denaturation temperatures were determined to be 31.5 and 31.0oC, respectively. Both collagens exhibited high solubility in acidic pH (1–5) and below 4% (w/v) NaCl concentration.
Peck, Jacquelin,Nguyen, Anh Thy H.,Dey, Aditi,Amankwah, Ernest K.,Rehman, Mohamed,Wilsey, Michael The Korean Society of Pediatric Gastroenterology 2021 Pediatric gastroenterology, hepatology & nutrition Vol.24 No.1
Purpose: Percutaneous endoscopic gastrostomy (PEG) tube placements are commonly performed pediatric endoscopic procedures. Because of underlying disease, these patients are at increased risk for airway-related complications. This study compares patient characteristics and complications following initial PEG insertion with general endotracheal anesthesia (GETA) vs. anesthesia-directed deep sedation with a natural airway (ADDS). Methods: All patients 6 months to 18 years undergoing initial PEG insertion within the endoscopy suite were considered for inclusion in this retrospective cohort study. Selection of GETA vs. ADDS was made by the anesthesia attending after discussion with the gastroenterologist. Results: This study included 168 patients (GETA n=38, ADDS n=130). Cohorts had similar characteristics with respect to sex, race, and weight. Compared to ADDS, GETA patients were younger (1.5 years vs. 2.9 years, p=0.04), had higher rates of severe American Society of Anesthesiologists (ASA) disease severity scores (ASA 4-5) (21% vs. 3%, p<0.001), and higher rates of cardiac comorbidities (39.5% vs. 18.5%, p=0.02). Significant associations were not observed between GETA/ADDS status and airway support, 30-day readmission, fever, or pain medication in unadjusted or adjusted models. GETA patients had significantly increased length of stay (eβ=1.55, 95% confidence interval [CI]=1.11-2.18) after adjusting for ASA class, room time, anesthesia time, fever, and cardiac diagnosis. GETA patients also had increased room time (eβ=1.20, 95% CI=1.08-1.33) and anesthesia time (eβ=1.50, 95% CI=1.30-1.74) in adjusted models. Conclusion: Study results indicate that younger and higher risk patients are more likely to undergo GETA. Children selected for GETA experienced longer room times, anesthesia times, and hospital length of stay.
Malaysian Freshwater Fish: Exploitable Source for Collagen Extraction
Peck Loo Kiew,Mashitah Mat Don 중소기업융합학회 2015 중소기업융합학회 국제학술대회논문집 Vol.2 No.1
Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were extracted from the skin of cultured hybrid catfish (Clarias gariepinus X Clarias macrocephalus), red tilapia (Oreochromis niloticus), black tilapia (Oreochromis mossambicus), pangasius catfish (Pangasianodon hypophthalmus), sultan fish (Leptobarbus hoevenii), and labyrinth fish (Trichogaster trichopterus), freshwater fishes that are widely consumed in Malaysia. The extracted yields for all selected species were higher for PSC as compared to ASC. Among all, catfish of the hybrid Clarias sp. contained the highest amount of skin collagen, both ASC and PSC at 36.73 ± 0.51 % and 58.17 ± 0.54 %, respectively. The extracted collagens were confirmed as type I collagen based on the SDSPAGE analysis and amino acid composition. Both ASC and PSC had glycine as the major amino acid and no cysteine was found in any of the extracted collagen. This was consistent with reported characteristics of type I collagen in the literature. Presence of collagen in the skin of these fishes showed the possibility to convert these natural resources into value-added product such as collagen, thus aids in improving their commercial values whilst assisting in ensuring the sustainability of Malaysian freshwater fishes.
Peck, Jacquelin,Sapp, Kaitlin,Wilsey, Alexander,Wilsey, Michael The Korean Society of Pediatric Gastroenterology 2019 Pediatric gastroenterology, hepatology & nutrition Vol.22 No.1
Buried bumper syndrome is a rare but potentially severe complication of percutaneous endoscopic gastrostomy tube insertion. Though this complication is uncommon, it may lead to pressure necrosis, bleeding, perforation, peritonitis, sepsis, or death. Each case of buried bumper syndrome is unique in terms of patient comorbidities and anatomic positioning of the buried bumper. For this reason, many approaches have been described in the management of buried bumper syndrome. In this case report, we describe the case of an adolescent Caucasian female who developed buried bumper syndrome three years after undergoing percutaneous endoscopic gastrostomy insertion. We review diagnosis and management of buried bumper syndrome and describe a novel technique for bumper removal in which we use a guide wire in combination with external traction to maintain a patent gastrostomy lumen while removing the internal percutaneous endoscopic gastrostomy bumper.