Publications by authors named "Jung-Hun Kim"

43 Publications

Enhancement of sophorolipids production in Candida batistae, an unexplored sophorolipids producer, by fed-batch fermentation.

Bioprocess Biosyst Eng 2021 Apr 8;44(4):831-839. Epub 2021 Mar 8.

Bio-Based Chemistry Research Center, Korea Research Institute of Chemical Technology (KRICT), 406-30, Jongga-ro, Ulsan, 44429, Republic of Korea.

Sophorolipids (SLs) from Candida batistae has a unique structure that contains ω-hydroxy fatty acids, which can be used as a building block in the polymer and fragrance industries. To improve the production of this industrially important SLs, we optimized the culture medium of C. batistae for the first time. Using an optimized culture medium composed of 50 g/L glucose, 50 g/L rapeseed oil, 5 g/L ammonium nitrate and 5 g/L yeast extract, SLs were produced at a concentration of 24.1 g/L in a flask culture. Sophorolipids production increased by about 19% (28.6 g/L) in a fed-batch fermentation using a 5 L fermentor. Sophorolipids production more increased by about 121% (53.2 g/L), compared with that in a flask culture, in a fed-batch fermentation using a 50 L fermentor, which was about 787% higher than that of the previously reported SLs production (6 g/L). These results indicate that a significant increase in C. batistae-derived SLs production can be achieved by optimization of the culture medium composition and fed-batch fermentation. Finally, we successfully separated and purified the SLs from the culture medium. The improved production of SLs from C. batistae in this study will help facilitate the successful development of applications for the SLs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00449-020-02493-4DOI Listing
April 2021

3D print material study to reproduce the function of pig heart tissue.

Technol Health Care 2021 ;29(S1):27-34

Department of Radiology, School of Medicine, Kyungpook National University, Sangyeok-dong, Buk-gu, Daegu, South Korea.

Background: Three-dimensional (3D) printing technology for heart simulation can be represented as complex anatomical structures, and objective information can be provided.

Objective: We studied 3D print material to find a material with the same elastic coefficient as pig elastic coefficient.

Methods: Pig heart sample, Agilus sample, Tango sample, TPU sample, and silicone sample were studied. The elastic coefficient of each specimen was measured using an elastic coefficient measuring instrument. The analysis was performed using the average value of ten specimens of the same size. We suggested an equation to find the elastic coefficient of material by the thickness using the elastic coefficient of Agilus, Tango, and silicone.

Results: The sample with similar elasticity to the pig sample did not show the same coefficient of elasticity at the same sample size. In Tango, the 0.5 mm high elastic force was about 3 times higher than the pig sample 7 mm elastic force.

Conclusions: The study was conducted using 3D print material and silicone which can reproduce the elasticity of pig heart. However, no material is currently available to reproduce pig heart sample of the same size. However, if the heart is developed considering only elasticity, it can be sufficiently reproduced using the research results.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3233/THC-218003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8150471PMC
January 2021

Comparative study on carbon dioxide-cofed catalytic pyrolysis of grass and woody biomass.

Bioresour Technol 2021 Mar 30;323:124633. Epub 2020 Dec 30.

Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea. Electronic address:

This study investigated the mechanistic functions of CO on the pyrolysis of two different biomasses to elucidate the effect of CO on syngas formations during pyrolysis. To this end, CO-assisted pyrolysis of cellulosic biomass (barnyard grass, Echinochloa) and lignin-rich woody biomass (retinispora, Chamaecyparis obtusa) were compared. The confirmed mechanistic effectiveness of CO on pyrolysis of biomass was gas phase reactions between CO and volatile matters from biomass pyrolysis. Lignin-rich biomass had more CO susceptibility, resulting in more enhanced CO formation via the gas phase reactions. To expedite the slow reaction rate of the gas phase reactions during biomass pyrolysis, earth-abundant catalysts (Co/SiO and Ni/SiO) were employed for pyrolysis of two biomass substrates. With Co and Ni catalysts, the syngas formations were 2 and 3 times higher comparing to the pyrolysis of without catalyst. The cumulative formations of syngas from lignin-rich biomass was nearly doubled than that from cellulosic biomass.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biortech.2020.124633DOI Listing
March 2021

Ultrasonographic evaluation of chronic shoulder pain after breast cancer surgery: single center, cross-sectional study.

Sci Rep 2020 10 8;10(1):16792. Epub 2020 Oct 8.

Division of Rheumatology, Department of Internal Medicine, Konkuk University Medical Center, 120-1 Neungdong-ro (Hwayang-dong), Gwangjin-gu, Seoul, 05030, Republic of Korea.

Chronic shoulder pain is a common complication in breast cancer patients after surgery. Chronic shoulder pain after breast cancer surgery was formerly considered as neuropathic pain, however the pathophysiology including structural damages has not been assessed comprehensively. We hypothesized that the structural change could be one of the cause of shoulder pain after breast cancer surgery and evaluated various ultrasonography findings of the shoulder in breast cancer patients with chronic shoulder pain. Patients who were suffering from chronic shoulder pain on unilateral side for at least 3 months after breast cancer surgery were enrolled from a single tertiary hospital. Demographic and clinical data were collected at the baseline. Articular and adjacent structures of both shoulders (painful and contralateral side) were evaluated by ultrasonography. The ultrasonography findings were compared between painful and contralateral sides. Logistic regression analysis was performed to determine the factors associated with abnormal ultrasonography findings. Fifty-two female patients (average age of 55) were enrolled. Significantly more abnormal ultrasonography findings were observed in the painful side than in the contralateral side [39 (75.0%) vs 11 (21.2%), P < 0.001]. The coracohumeral ligament was significantly thicker in the painful side than in the contralateral side (2.48 ± 0.69 vs 1.54 ± 1.25 mm, P < 0.001); adhesive capsulitis was also more frequent in the painful side [14 (26.9%) vs 0, P < 0.001]. Furthermore, patients with a history of breast cancer surgery on the ipsilateral side were associated with abnormal ultrasonography findings and adhesive capsulitis. This study is the first to evaluate ultrasonography in patients with chronic shoulder pain after breast cancer surgery. The results showed that ultrasonography could reveal several structural problems in these patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-020-73769-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7546622PMC
October 2020

Sequential growth factor releasing double cryogel system for enhanced bone regeneration.

Biomaterials 2020 10 10;257:120223. Epub 2020 Jul 10.

Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, 08826, Republic of Korea; School of Chemical and Biological Engineering, The Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea; BioMAX/N-Bio Institute, Institute of BioEngineering, Seoul National University, Seoul, 08826, Republic of Korea. Electronic address:

Bone regeneration is a complicated physiological process regulated by several growth factors. In particular, vascular endothelial growth factor (VEGF) and bone morphogenetic protein-4 (BMP-4) are regarded as key factors that induce bone regeneration by angiogenesis and osteogenesis. In this study, we developed a double cryogel system (DC) composed of gelatin/chitosan cryogel (GC) surrounded by gelatin/heparin cryogel (GH) for dual drug delivery with different release kinetics. VEGF was loaded in GH (outer layer of DC) for the initial release of VEGF to induce angiogenesis and provide blood supply in the defect area, while BMP-4 was loaded in GC (inner layer of DC) that leads to sustained release for continuous osteogenic induction. After analyzing characteristics of the double cryogel system such as porosity, degradation rate, swelling ratio, and mechanical properties, we evaluated release kinetics of VEGF (initial release) and BMP-4 (sustained-release) by ELISA. Then, the timely release of VEGF and BMP from DC synergistically induced in vitro osteogenic differentiation as confirmed by alkaline phosphatase staining, Alizarin Red S staining, and real-time PCR analysis. Finally, a critical-sized cranial defect model confirmed the enhanced bone regeneration as a result of dual release growth factor mechanisms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biomaterials.2020.120223DOI Listing
October 2020

Metabolic Syndrome and the Risk of Thyroid Cancer: A Nationwide Population-Based Cohort Study.

Thyroid 2020 10 15;30(10):1496-1504. Epub 2020 Jul 15.

Department of Biostatistics, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

The association of metabolic syndrome and its components with the risk of thyroid cancer is unclear. Thus, we conducted a large-scale, nationwide, population-based, cohort study to investigate this relationship. We studied 9,890,917 adults without thyroid cancer from the Korean National Health Insurance health checkup database from January 1 to December 31, 2009. Individuals with at least three of the following five components were diagnosed with metabolic syndrome: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein-cholesterol levels, elevated blood pressure, and hyperglycemia. Multivariate Cox proportional hazards models were used to estimate thyroid cancer risk. During the average 7.2 years of follow-up, 77,133 thyroid cancer cases were newly identified. The thyroid cancer risk was higher in the metabolic syndrome group than in the nonmetabolic syndrome group (hazard ratio [HR] 1.15 [95% confidence interval, CI 1.13-1.17]). The association between metabolic syndrome and thyroid cancer risk was significant in the obese group (HR 1.10 [CI 1.07-1.13]) and not in the nonobese group (HR 1.002 [CI 0.98-1.03]). The effect of metabolic syndrome on the risk of thyroid cancer differs according to obesity ( for interaction = 0.017). People with all five components of metabolic syndrome had a 39% higher risk than those without any components (HR 1.39 [CI 1.33-1.44]). The higher risk of thyroid cancer in people with all five components was significant in the obese group (HR 1.29 [CI 1.21-1.38]), but not in the nonobese group (HR 1.06 [CI 0.98-1.14]). There was a significant interaction between the number of metabolic syndrome components and obesity ( for interaction <0.0001). For the combined effect of obesity and metabolic syndrome on the risk of thyroid cancer, obese men with metabolic syndrome had the highest risk of thyroid cancer compared with those without (HR 1.58 [CI 1.52-1.64]), but obese women with metabolic syndrome did not. Metabolic syndrome was associated with an increased risk of thyroid cancer in the Korean general population. Metabolic syndrome had a more significant risk of thyroid cancer in the obese group. Metabolic syndrome and obesity were associated with a higher risk of thyroid cancer in men but not in women.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/thy.2019.0699DOI Listing
October 2020

CO-cofed catalytic pyrolysis of tea waste over Ni/SiO for the enhanced formation of syngas.

J Hazard Mater 2020 09 8;396:122637. Epub 2020 Apr 8.

Department of Environment and Energy, Sejong University, Seoul, 05006, Republic of Korea. Electronic address:

To valorize tea waste (TW), catalytic pyrolysis was done as a practical measure for recovering energy as a form of syngas. Considering CO as a reactive gas medium in place of conventional pyrolysis gas, a sustainable pyrolysis platform was established. In addition, mechanistic effectiveness of CO on TW pyrolysis was examined. In the presence of CO, homogeneous reaction with volatile organic compounds (VOCs) derived from TW pyrolysis contributed to CO formation. To enhance the formation of syngas at low pyrolysis temperature, catalytic pyrolysis over a Ni/SiO was investigated. The synergistic effects of Ni/SiO catalyst and CO promoted thermal cracking of VOCs and further homogeneous reaction with CO, thereby resulting in the substantial enhancement (28 times more) of H and CO production than non-catalytic pyrolysis. It was also confirmed that CO could be considered a reactive gas medium to produce biochar (34-35 wt.% yield), having competitive porosity and surface area, in comparison to that from pyrolysis in N. Therefore, CO can be employed to build a sustainable waste conversion platform for energy and biochar production through pyrolysis instead of using N.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2020.122637DOI Listing
September 2020

3-D Space Visualization System Using Ultrasonic Sensors as an Assistive Device for the Blind.

IEEE J Transl Eng Health Med 2020 12;8:2700305. Epub 2020 Mar 12.

School of Electronics EngineeringKyungpook National UniversityDaegu41566South Korea.

This study proposes a new assistive device for the blind that uses more than one-dimensional data to draw objects. The study aims to convert three-dimensional (3-D) spatial information into sound information using 6-axis and ultrasonic sensors, and to draw a 3-D depiction of the space ahead for the user. Fourteen participants were involved in testing, wherein 4 were visually impaired. Moreover, the male to female ratio was 7:3, with the average age of participants at 28.8 years. An initial sound recognition experiment was designed to assess the device's accuracy through participant use. Recognition rates were 70% for normal participants and 88% for the blind participants. Additional experiments expanded the environmental conditions by requiring participants to discern the distances of 10 objects, positioned at both high and low locations. Two different scenarios were employed: stationary and walking scenarios. The stationary distance measurement participants scored an average of 96 points, while the walking participants averaged 81 points. Under the given conditions, this study found that its assistive device for the visually impaired can draw a 3-D space with 88.5% accuracy. This probability promises a basic level of utility that can assist those with visual impairment in controlled environments, such as hospitals and homes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/JTEHM.2020.2978842DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7098878PMC
March 2020

Analysis of Correlation Between Contrast and Component of Polylatic Acid Composite for Fused Deposition Modeling 3D Printing.

J Nanosci Nanotechnol 2020 08;20(8):5107-5111

National Institute for Nanomaterials Technology, Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang, Gyeongbuk, 37673, Korea.

Additive manufacturing or three-dimensional (3D) printing is considered a disruptive technology for producing components with topologically optimized complex geometries as well as functionalities that are not achievable by traditional methods. 3D printing is expected to revolutionize the manufacturing of components. While several 3D printing systems are available, printing based on fused-deposition modeling (FDM) using thermoplastics is particularly widespread because of the simplicity and potential applicability of the method. In this study, we report the analysis of correlation between contrast and component of polylactic acid (PLA) based composite for FDM 3D printing. The pre-fabricated white composite and black composite were mixed in the fraction of 100:0, 90:10, 75:25, 50:50, 25:75, and 0:100% (v/v) and the obtained mixture was extruded using HX-35 3D filament extrusion line. The samples in different contrast were printed in disk like shape, and the gray scale filaments and 3D printed samples were measured the morphology and components using a field emission scanning electron microscope and energy dispersive X-ray spectroscopy. The CIE-lab values of the samples were measured using a colorimeter and the correlation between CIE-lab values and the components were analyzed. Although the component of Ti was linearly increased, the CIE-lab values show a clear exponential increase by increasing the white composite.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1166/jnn.2020.17835DOI Listing
August 2020

High-level production and high-yield recovery of lactobionic acid by the control of pH and temperature in fermentation of Pseudomonas taetrolens.

Bioprocess Biosyst Eng 2020 May 15;43(5):937-944. Epub 2020 Feb 15.

Bio-based Chemistry Research Center, Korea Research Institute of Chemical Technology (KRICT), 406-30 Jongga-ro, Ulsan, 44429, Republic of Korea.

Lactobionic acid (LBA) was produced by fermentation of Pseudomonas taetrolens. First, to increase the production of LBA by P. taetrolens, we controlled the pH of culture medium by CaCO addition (30 g/L) and then examined the initial lactose concentration ranging from 50 to 200 g/L and the growth temperature ranging from 20 to 37 °C. Both the LBA production titer (180 g/L) and the productivity (2.5 g/L h) were highest at 200 g/L lactose concentration and 25 °C of cell growth temperature in shake-flask culture. Although the production of LBA (178 g/L) was almost similar during the batch fermentation of P. taetrolens using 5 L bioreactor, the LBA productivity highly increased to 4.9 g/L h. The method using ethanol precipitation and ion-exchange chromatography was developed to recover the pure LBA from the fermentation broth. The optimum volume of ethanol and pH of culture medium for the precipitation of Ca salt form of LBA were six volume of ethanol and pH 6.5, respectively. The cation-exchange resin T42 finally showed the best recovery yield (97.6%) of LBA from the culture supernatant. The production titer (178 g/L) and the productivity (4.9 g/L h) of lactobionic acid in this study were highest among the previous studies ever reported using P. taetrolens as a production strain of LBA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00449-020-02290-zDOI Listing
May 2020

Application of chemical reaction engineering principles to 'body-on-a-chip' systems.

AIChE J 2018 Dec 12;64(12):4351-4360. Epub 2018 Oct 12.

Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA.

The combination of cell culture models with microscale technology has fostered emergence of cell-based microphysiological models, also known as organ-on-a-chip systems. Body-on-a-chip systems, which are multi-organ systems on a chip to mimic physiological relations, enable recapitulation of organ-organ interactions and potentially whole-body response to drugs, as well as serve as models of diseases. Chemical reaction engineering principles can be applied to understanding complex reactions inside the cell or human body, which can be treated as a multi-reactor system. These systems use physiologically-based pharmacokinetic (PBPK) models to guide the development of microscale systems of the body where organs or tissues are represented by living cells or tissues, and integrated into body-on-a-chip systems. Here, we provide a brief overview on the concept of chemical reaction engineering and how its principles can be applied to understanding and predicting the behavior of body-on-a-chip systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/aic.16448DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6688854PMC
December 2018

Development of a visual information to auditory information transformation system for ambulation assistance.

Technol Health Care 2019 ;27(S1):165-173

Jeyun Medical Inc., Hosan-dong, Daegu, Korea.

Background: Assistant equipment for the visually impaired has a white cane. If the information in the three-dimensional space is transmitted by sound, the blind can draw a three-dimensional space.

Objective: This study developed "Visual System," an ambulation aid/guide for the blind that transforms visual-spatial information into auditory information, and verified its utility. Unlike conventional systems, which are in essence simple collision-warning systems, Visual System helps the visually impaired to recreate their surroundings and to be cognizant of the location and proximity of obstacles.

Methods: Ten subjects with normal vision (mean age: 32.4 years; male-to-female ratio: 6 to 4) were selected for blind tests. The subjects were instructed to detect and avoid obstacles presented in various three-dimensional settings. Prior to the tests, experiments were conducted to determine the distance to each subject. Upon completion of Visual System-based detection training, obstacles were presented and tests conducted. For evaluation, the subjects' vertical position detection, horizontal position detection, distance detection, and overall performance success were each evaluated.

Results: The total performance scores ranged between 88 (lowest) and 100 (highest), with a mean score of 91.5.

Conclusions: The results indicate that Visual System as a product can assist the visually impaired in their daily functioning.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3233/THC-199016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6598023PMC
January 2020

Bioactive calcium phosphate materials and applications in bone regeneration.

Biomater Res 2019 14;23. Epub 2019 Jan 14.

1Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, 152-742 Republic of Korea.

Background: Bone regeneration involves various complex biological processes. Many experiments have been performed using biomaterials in vivo and in vitro to promote and understand bone regeneration. Among the many biomaterials, calcium phosphates which exist in the natural bone have been conducted a number of studies because of its bone regenerative property. It can be directly contributed to bone regeneration process or assist in the use of other biomaterials. Therefore, it is widely used in many applications and has been continuously studied.

Mainbody: Calcium phosphate has been widely used in bone regeneration applications because it shows osteoconductive and in some cases osteoinductive features. The release of calcium and phosphorus ions regulates the activation of osteoblasts and osteoclasts to facilitate bone regeneration. The control of surface properties and porosity of calcium phosphate affects cell/protein adhesion and growth and regulates bone mineral formation. Properties affecting bioactivity vary depending on the types of calcium phosphates such as HAP, TCP and can be utilized in various applications because of differences in ion release, solubility, stability, and mechanical strength. In order to make use of these properties, different calcium phosphates have been used together or mixed with other materials to complement their disadvantages and to highlight their advantages. Calcium phosphate has been utilized to improve bone regeneration in ways such as increasing osteoconductivity for bone ingrowth, enhancing osteoinductivity for bone mineralization with ion release control, and encapsulating drugs or growth factors.

Conclusion: Calcium phosphate has been used for bone regeneration in various forms such as coating, cement and scaffold based on its unique bioactive properties and bone regeneration effectiveness. Additionally, several studies have been actively carried out to improve the efficacy of calcium phosphate in combination with various healing agents. By summarizing the properties of calcium phosphate and its research direction, we hope that calcium phosphate can contribute to the clinical treatment approach for bone defect and disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s40824-018-0149-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6332599PMC
January 2019

Successive complementary model-based experimental designs for parameter estimation of fed-batch bioreactors.

Bioprocess Biosyst Eng 2018 Dec 11;41(12):1767-1777. Epub 2018 Aug 11.

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

When a dynamic model is used for the description of (fed-)batch bioreactors, it is typical that the model parameters are highly correlated to each other. In this case, it is important to keep the parameter correlation as small as possible to obtain a reliable set of parameter estimates. In this study, we propose an anticorrelation parameter estimation scheme that can be best utilized when a number of different batch experiments are sequentially processed. The scheme iteratively performs parameter estimation and model-based design of experiment (MBDOE) at the beginning and between the batches. The important difference from the existing approaches is that the MBDOE objective is defined according to the system analysis performed a priori, so that each new batch supplements what is lacking from the previous batches combined, in terms of information. The use of the scheme is illustrated on a fed-batch bioreactor model.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00449-018-1999-8DOI Listing
December 2018

Successful treatment of tracheoesophageal fistula using a covered esophageal stent.

Korean J Intern Med 2019 09 16;34(5):1165-1166. Epub 2018 May 16.

Department of Internal Medicine, Konkuk University Medical Center, Seoul, Korea.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3904/kjim.2017.347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6718744PMC
September 2019

Isoprene production by Escherichia coli through the exogenous mevalonate pathway with reduced formation of fermentation byproducts.

Microb Cell Fact 2016 Dec 23;15(1):214. Epub 2016 Dec 23.

Division of Applied Life Science (BK21 Plus), PMBBRC, Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, 52828, South Korea.

Background: Isoprene, a volatile C5 hydrocarbon, is an important platform chemical used in the manufacturing of synthetic rubber for tires and various other applications, such as elastomers and adhesives.

Results: In this study, Escherichia coli MG1655 harboring Populus trichocarpa isoprene synthase (PtispS) and the exogenous mevalonate (MVA) pathway produced 80 mg/L isoprene. Codon optimization and optimal expression of the ispS gene via adjustment of the RBS strength and inducer concentration increased isoprene production to 199 and 337 mg/L, respectively. To augment expression of MVA pathway genes, the MVA pathway was cloned on a high-copy plasmid (pBR322 origin) with a strong promoter (P), which resulted in an additional increase in isoprene production up to 956 mg/L. To reduce the formation of byproducts derived from acetyl-CoA (an initial substrate of the MVA pathway), nine relevant genes were deleted to generate the E. coli AceCo strain (E. coli MG1655 ΔackA-pta, poxB, ldhA, dld, adhE, pps, and atoDA). The AceCo strain harboring the ispS gene and MVA pathway showed enhanced isoprene production of 1832 mg/L in flask culture with reduced accumulation of byproducts.

Conclusions: We achieved a 23-fold increase in isoprene production by codon optimization of PtispS, augmentation of the MVA pathway, and deletion of genes involved in byproduct formation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12934-016-0612-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5180398PMC
December 2016

Primary oesophageal small cell carcinoma initially manifestating as purulent pericardiac effusion.

BJR Case Rep 2017 22;3(1):20160051. Epub 2016 Sep 22.

Department of Oncology, Hallym University College of Medicine, Chuncheon, South Korea.

This article reports a case of primary oesophageal small cell carcinoma with a large amount of purulent pericardial effusion due to oesophageal rupture. The patient was treated with chemotherapy, which resulted in a marked decrease in the size of the oesophageal mass and partial resolving of metastatic lymphadenopathy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1259/bjrcr.20160051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6159296PMC
September 2016

Synthesis of novel arylaminoquinazolinylurea derivatives and their antiproliferative activities against bladder cancer cell line.

Bioorg Med Chem Lett 2016 10 24;26(20):5082-5086. Epub 2016 Aug 24.

Chemical Kinomics Research Center, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea. Electronic address:

A novel series of arylurea and arylamide derivatives 1a-z, 2a-d having aminoquinazoline scaffold was designed and synthesized. Their in vitro antiproliferative activities against RT112 bladder cancer cell line and inhibitory activities against FGFR3 kinase were tested. Most compounds showed good antiproliferative activities against RT112 bladder cancer cell line, and arylurea compounds 1a-z were more potent than arylamide compounds 2a-d. Among them, eight compounds 1a, 1d-g, 1l, 1y, and 1z showed potent activities with GI values below submicromolar range. Especially, arylurea compounds 1d and 1g possessing 2,3-dimethyl and 3,4-dimethyl moieties exhibited superior or similar antiproliferative activity (GI=8.8nM and 30.2nM, respectively) to AZD4547 (GI=29.2nM) as a reference standard.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmcl.2016.08.076DOI Listing
October 2016

Light Harvesting Over Wide Range of Wavelengths by Rainbow Dye-Sensitized Solar Cells.

J Nanosci Nanotechnol 2016 Feb;16(2):1553-7

Three natural dyes, i.e., yellow, red, and blue, were extracted from gardenia and used as sensitizers in the assembly of rainbow dye-sensitized solar cells (DSSCs) to harvest light over a wide range of wavelengths. The adsorption characteristics, photovoltaic efficiencies, and electrochemical properties of the rainbow DSSCs were investigated. Adsorption kinetic data for the dyes were obtained in a small adsorption, chamber. The data fitted a pseudo-second-order model. The photovoltaic performance of a photo-electrode with an adsorbed mixture of the three dyes was evaluated from current-voltage measurements.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1166/jnn.2016.11943DOI Listing
February 2016

A nondestructive approach for discrimination of the origin of sesame seeds using ED-XRF and NIR spectrometry with chemometrics.

Food Sci Biotechnol 2016 30;25(2):433-438. Epub 2016 Apr 30.

1School of Food Science and Biotechnology, Kyungpook National University, Daegu, 41566 Korea.

An energy dispersive X-ray fluorescence (ED-XRF) spectrometer and a near infrared (NIR) spectrometer combined with chemometrics were applied for origin discrimination of 48 Korean, 44 Chinese, and 21 Indian sesame seed samples used for development of a discriminant calibration model. Multi-elemental ED-XRF analysis based on Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, and Cu was used for comparisons among origins. All elements, except for Fe, showed differences and 96.5% of seed samples were assigned to the correct origin using discriminant analysis based on chemical analytical results. NIR measurements were performed for spectral scanning. Classification of seeds using NIR discriminant analysis achieved 89.4% of seed samples assigned to the correct origin. Both ED-XRF and NIR are useful as nondestructive tools for discrimination of sesame seed origins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10068-016-0059-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6049197PMC
April 2016

Optimization of microalgal photobioreactor system using model predictive control with experimental validation.

Bioprocess Biosyst Eng 2016 Aug 19;39(8):1235-46. Epub 2016 Apr 19.

Institute of Chemical Processes, School of Chemical and Biological Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

To maximize biomass and lipid concentrations, various optimization methods were investigated in microalgal photobioreactor systems under mixotrophic conditions. Lipid concentration was estimated using unscented Kalman filter (UKF) with other measurable sources and subsequently used as lipid data for performing model predictive control (MPC). In addition, the maximized biomass and lipid trajectory obtained by open-loop optimization were used as target trajectory for tracking by MPC. Simulation studies and experimental validation were performed and significant improvements in biomass and lipid productivity were achieved in the case where MPC was applied. However, occurence of a lag phase was observed while manipulating the feed flow rates, which is induced by large amount of inputs. This is an important phenomenon that can lead to model-plant mismatch and requires further study for the optimization of microalgal photobioreactors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00449-016-1602-0DOI Listing
August 2016

Analysis of Chameleonic Change of Red Cabbage Depending on Broad pH Range for Dye-Sensitized Solar Cells.

J Nanosci Nanotechnol 2015 Aug;15(8):5840-4

Dye-sensitized solar cells (DSSCs) were assembled using natural dyes extracted from red cabbage as a sensitizer. In this work, we investigated the adsorption characteristics and the electrochemical behavior for harvesting sunlight and electron transfer in red cabbage DSSCs under different solvents and pH. For the red cabbage dye-sensitized electrode adsorbed at pH 3.5, the solar cell yields a short-circuit current density (Jsc) of 1.60 mA/cm2, a photovoltage (Vcc) of 0.46 V, and a fill factor of 0.55, corresponding to an energy conversion efficiency (η) of 0.41%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1166/jnn.2015.10480DOI Listing
August 2015

Toxic metal content in 52 frequently prescribed herbal medicines on the Korean market.

Food Addit Contam Part B Surveill 2015 25;8(3):199-206. Epub 2015 Jul 25.

a Seoul Metropolitan Government Research Institute of Public Health and Environment , Gwacheon-si, Gyeonggi-do , Korea.

This study was conducted to investigate the toxic metal content (Pb, As, Cd and Hg) of 52 frequently prescribed herbal medicines and to identify herbal medicines that exceed the Korea Food and Drug Administration (KFDA) maximum limits. A total of 3534 samples, including 1966 domestic samples and 1568 imported samples, were analysed using an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Total amounts of Pb, As, Cd and Hg were significantly different between domestic (0.63 mg kg(-1)) and imported (0.81 mg kg(-1)) medicines (p < 0.05). Among the 52 kinds of samples, 4 kinds of herbs required quality control for Pb and 12 kinds of herbs required quality control for Cd. No sample contained As and Hg above the limits.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/19393210.2015.1046405DOI Listing
May 2016

Food intake survey of kindergarten children in Korea: Part 2 increased dietary intake of tin possibly associated with canned foods.

Environ Health Prev Med 2015 Jul 21;20(4):302-6. Epub 2015 May 21.

Seoul Metropolitan Government Research Institute of Public Health and Environment, Seoul, 137-734, Korea.

Objectives: Dietary intake of tin (Sn) may be increased in some children in kindergartens in Korea. The present study was intended to examine this possibility and clarify the extent of the elevation.

Methods: 24-hour food duplicate and spot urine samples were collected in 2003-2004 from 108 4-6-year-old children (boys and girls combined) in 4 kindergartens (1 in Seoul and 3 in Jeju Island), as reported in a previous publication. These samples were employed in the present analyses to examine tin levels in the diet (including beverages) (Sn-D). A portion of the samples were wet-ashed, and the liquid samples were analyzed for Sn by the ICP-MS method. For statistical evaluation, χ (2) method and Smirnov's test for extreme value were used.

Results: Sn-D in the 108 cases distributed as extremely biased, and could be divided into two groups, i.e., those with <10 μg Sn/day (accounting for 90% of the cases), and those with >10 μg/day (for 10%). Sn-D in the former group was distributed quasi-normally with an AM (median) of 2.9 (2.5) μg/day. The maximum in the latter group was 3012 μg/day. No correlation was detected between Sn-D and Sn in urine (Sn-U). Comparison of the findings with published articles strongly suggested that the high Sn-D was due to consumption of foods (including beverages) preserved in tin-plated cans. No positive confirmation was however possible due to insufficient information on food records.

Conclusions: About 10% of children surveyed had elevated Sn-D (up to 3 mg/day). It was quite possible that high Sn-D was associated with tin-canned food intake.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12199-015-0466-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4491055PMC
July 2015

Patterned growth of Au nanoparticles on polycrystalline lead zirconate titanate surfaces.

J Nanosci Nanotechnol 2014 Oct;14(10):7985-9

We report the patterned growth of Au nanoparticles (NPs) on polarity-patterned polycrystalline lead zirconate titanate (PZT) as a template through photochemical reaction. The photochemical deposition of the Au NPs includes ultraviolet (UV) light illumination of the patterned PZT while immersed in a HAuCl4 solution. In particular, the influence of the UV wavelength, and the influence of the solution with the stabilizer and reducer on the growth selectivity of the Au NPs on the polarity-patterned regions was investigated. For a UV light of 365 nm wavelength, corresponding to a band-gap excitation of the PZT, more Au NPs were deposited on the + z polar region than on the other non-polar regions. However, no deposition of the Au NPs was observed for UV light wave-lengths longer than - 365 nm. When ascorbic acid (AA) as a reducer and cetyl-trimethylammonium bromide (CTAB) as a stabilizer were added to the HAuCl4 solution, the Au NPs on the + z polar region were observed to be deposited with a UV light of 435 nm, which is larger than the optical band gap wavelength of the PZT. Also, the growth selectivity and size uniformity on the + z region was significantly improved. These results could be due to the defect-induced photo-excitation of electrons and enhanced reduction process of Au+ ions by adding the reducer and the stabilizer in the photo-chemical process. This study suggests the possibility of the patterned growth of Au NPs on a ferroelectric surface through polarity patterning and photochemical reaction by optimizing the UV wavelength and employing reduction potential agents in a metal salt solution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1166/jnn.2014.9432DOI Listing
October 2014

A comparative study of soft sensor design for lipid estimation of microalgal photobioreactor system with experimental validation.

Bioresour Technol 2015 Mar 16;179:275-283. Epub 2014 Dec 16.

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea. Electronic address:

This study examines the applicability of various nonlinear estimators for online estimation of the lipid concentration in microalgae cultivation system. Lipid is a useful bio-product that has many applications including biofuels and bioactives. However, the improvement of lipid productivity using real-time monitoring and control with experimental validation is limited because measurement of lipid in microalgae is a difficult and time-consuming task. In this study, estimation of lipid concentration from other measurable sources such as biomass or glucose sensor was studied. Extended Kalman filter (EKF), unscented Kalman filter (UKF), and particle filter (PF) were compared in various cases for their applicability to photobioreactor systems. Furthermore, simulation studies to identify appropriate types of sensors for estimating lipid were also performed. Based on the case studies, the most effective case was validated with experimental data and found that UKF and PF with time-varying system noise covariance is effective for microalgal photobioreactor system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biortech.2014.12.029DOI Listing
March 2015

Mercury contamination and exposure assessment of fishery products in Korea.

Food Addit Contam Part B Surveill 2015 10;8(1):44-9. Epub 2014 Dec 10.

a Seoul Government Research Institute of Public Health and Environment , Gwacheon , Gyunggi Province , Korea.

In this study, total (T-Hg) and methyl mercury (Me-Hg) contamination was investigated in fishery products including canned fish, fish sauces, dried bonito and frozen tuna sashimi, collected from retail markets in Korea, to assess dietary exposure. Direct mercury analyser and gas chromatography-electron captured detector were employed to measure T-Hg and Me-Hg, respectively. The highest T-Hg and Me-Hg contamination was present in tuna sashimi, followed by dried bonito, respectively. Canned tuna showed more frequent detection and higher content than other canned fishery products. The weekly exposure estimate indicates that exposure to mercury from fishery products is safe, showing 2.59% provisional tolerable weekly intake (PTWI) for T-Hg, 1.82% PTWI for Me-Hg and 4.16% reference dose for Me-Hg. However, it should be addressed to monitor the mercury contamination in fish and fishery products regularly, to safeguard vulnerable population such as children, to limit intake of these food products.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/19393210.2014.968808DOI Listing
October 2015

Synthetic biology and metabolic engineering for marine carotenoids: new opportunities and future prospects.

Mar Drugs 2014 Sep 17;12(9):4810-32. Epub 2014 Sep 17.

Division of Applied Life Science (BK21 Plus), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea.

Carotenoids are a class of diverse pigments with important biological roles such as light capture and antioxidative activities. Many novel carotenoids have been isolated from marine organisms to date and have shown various utilizations as nutraceuticals and pharmaceuticals. In this review, we summarize the pathways and enzymes of carotenoid synthesis and discuss various modifications of marine carotenoids. The advances in metabolic engineering and synthetic biology for carotenoid production are also reviewed, in hopes that this review will promote the exploration of marine carotenoid for their utilizations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/md12094810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4178492PMC
September 2014

Dynamic modelling of mixotrophic microalgal photobioreactor systems with time-varying yield coefficient for the lipid consumption.

Bioresour Technol 2014 Jun 31;162:228-35. Epub 2014 Mar 31.

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea. Electronic address:

Microalgae have been suggested as a promising feedstock for producing biofuel because of their potential for lipid production. In this study, microalgal photobioreactor systems under mixotrophic conditions were investigated, for the purpose of developing a mathematical model that predicts biomass and lipid production. The model was developed based on the Droop model, and the optimal input design using D-optimality criterion was performed to compute the system input profile, to estimate parameters more accurately. From the experimental observations, the newly defined yield coefficient was suggested to represent the consumption of lipid and nitrogen within the cell, which reduces the number of parameters with more accurate prediction. Furthermore, the lipid consumption rate was introduced to reflect the experimental results that lipid consumption is related to carbon source concentration. The model was validated with experiments designed with different initial conditions of nutrients and input changes, and showed good agreement with experimental observations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biortech.2014.03.128DOI Listing
June 2014

Light harvesting over a wide range of wavelength using natural dyes of gardenia and cochineal for dye-sensitized solar cells.

Spectrochim Acta A Mol Biomol Spectrosc 2014 Jul 24;128:868-73. Epub 2014 Mar 24.

Department of Chemical and Biochemical Engineering, Chosun University, Gwangju 501-759, Republic of Korea. Electronic address:

Two natural dyes extracted from gardenia yellow (Gardenia jasminoides) and cochineal (Dactylopius coccus) were used as sensitizers in the assembly of dye-sensitized solar cells (DSSCs) to harvest light over a wide range of wavelengths. The adsorption characteristics, electrochemical properties and photovoltaic efficiencies of the natural DSSCs were investigated. The adsorption kinetics data of the dyes were obtained in a small adsorption chamber and fitted with a pseudo-second-order model. The photovoltaic performance of a photo-electrode adsorbed with single-dye (gardenia or cochineal) or the mixture or successive adsorption of the two dyes, was evaluated from current-voltage measurements. The energy conversion efficiency of the TiO2 electrode with the successive adsorption of cochineal and gardenia dyes was 0.48%, which was enhanced compared to single-dye adsorption. Overall, a double layer of the two natural dyes as sensitizers was successfully formulated on the nanoporous TiO2 surface based on the differences in their adsorption affinities of gardenia and cochineal.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.saa.2014.03.016DOI Listing
July 2014