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Search Results: 1 - 10 of 21172 matches for " Seung Kim "
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Computer Simulation Study of Biopolymer Betanova  [PDF]
Seung-Yeon Kim
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.312002
Abstract:

Betanova is a monomeric, three-stranded antiparallel beta-sheet protein with twenty residues. The pathways between the folded native structure and unfolded conformations of betanova are studied using UNRES force field and the most popular computer simulation method, Metropolis Monte Carlo algorithm. At a fixed temperature, 100 Monte Carlo simulations are performed, starting from the folded native structure, and the pathways are obtained at two different temperatures.

Folding and Unfolding Simulations of a Three-Stranded Beta-Sheet Protein  [PDF]
Seung-Yeon Kim
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.41003
Abstract:

Understanding the folding processes of a protein into its three-dimensional native structure only with its amino-acid sequence information is a long-standing challenge in modern science. Two- hundred independent folding simulations (starting from non-native conformations) and two- hundred independent unfolding simulations (starting from the folded native structure) are performed using the united-residue force field and Metropolis Monte Carlo algorithm for betanova (three-stranded antiparallel beta-sheet protein). From these extensive computer simulations, two representative folding pathways and two representative unfolding pathways are obtained in the reaction coordinates such as the fraction of native contacts, the radius of gyration, and the root- mean-square deviation. The folding pathways and the unfolding pathways are similar each other. The largest deviation between the folding pathways and the unfolding pathways results from the root-mean-square deviation near the folded native structure. In general, unfolding computer simulations could capture the essentials of folding simulations.

Multidirectional instability of the shoulder – current concept
Seung-Ho Kim
Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology , 2009, DOI: 10.1186/1758-2555-1-12
Abstract: The multidirectional instability of the shoulder is a complex problem in terms of diagnosis and treatment. Distinct from multidirectional hyperlaxity, multidirectional instability has symptoms related with increased translations in more than one direction. Increased translation by the increased capsular ligamentous laxity is underlying pathology of the posterior and multidirectional instability. This increased capsular laxity can be in-borne or developmental and asymptomatic or minimally symptomatic initially. In this stage, attempted translation does not produce symptoms. Jerk and Kim tests reveal posterior clunk without shoulder pain [1,2].However, repetitive subluxation overloads the posteroinferior glenoid labrum by the excessive rim-loading of the humeral head. This excessive rim-loading eventually develops posteroinferior labral lesion varying from simple retroversion to incomplete detachment (Figure 1). In this stage, patient's symptom which is shoulder pain, originates from the labral lesion when the humeral head glides over the pathologic labrum. The compressive force on the torn labrum in the jerk and Kim tests generates shoulder pain. Therefore, intact labrum does not produce shoulder pain no matter how lax the glenohumeral joint is. Increased translation alone produces asymptomatic posterior clunk until the repetitive rim-loading eventually develops posteroinferior labral lesion [3].Four type of the labral lesion have been reported. The Kim lesion is a concealed and incomplete tear of the posteroinferior labrum which is characterized by loss of labral height and retroversion, marginal crack, and loose inside. The lesion is similar to the intratendinous tear of the rotator cuff in that it is not evident in the initial observation. The surgeon should be aware of the lesion and palpate with probe (Figure 2).The retroversion of the glenoid labrum decrease the containment function of the glenohumeral joint which further decrease the shoulder's stability (Figu
Structure and catalytic mechanism of human protein tyrosine phosphatome
Seung Jun Kim
BMB Reports , 2012,
Abstract: Together with protein tyrosine kinases (PTKs), protein tyrosinephosphatases (PTPs) serve as hallmarks in cellular signaltransduction by controlling the reversible phosphorylation oftheir substrates. The human genome is estimated to encodemore than 100 PTPs, which can be divided into elevensub-groups according to their structural and functionalcharacteristics. All the crystal structures of catalytic domains ofsub-groups have been elucidated, enabling us to understandtheir precise catalytic mechanism and to compare theirstructures across all sub-groups. In this review, I describe thestructure and mechanism of catalytic domains of PTPs in thestructural context.
Fisher zeros and Potts zeros of the Q-state Potts model for nonzero external magnetic field
Seung-Yeon Kim
Physics , 2003,
Abstract: The properties of the partition function zeros in the complex temperature plane (Fisher zeros) and in the complex $Q$ plane (Potts zeros) are investigated for the $Q$-state Potts model in an arbitrary nonzero external magnetic field $H_q$, using the exact partition function of the one-dimensional model.
Density of Yang-Lee zeros for the Ising ferromagnet
Seung-Yeon Kim
Physics , 2006, DOI: 10.1103/PhysRevE.74.011119
Abstract: The densities of Yang-Lee zeros for the Ising ferromagnet on the $L\times L$ square lattice are evaluated from the exact grand partition functions ($L=3\sim16$). The properties of the density of Yang-Lee zeros are discussed as a function of temperature $T$ and system size $L$. The three different classes of phase transitions for the Ising ferromagnet, first-order phase transition, second-order phase transition, and Yang-Lee edge singularity, are clearly distinguished by estimating the magnetic scaling exponent $y_h$ from the densities of zeros for finite-size systems. The divergence of the density of zeros at Yang-Lee edge in high temperatures (Yang-Lee edge singularity), which has been detected only by the series expansion until now for the square-lattice Ising ferromagnet, is obtained from the finite-size data. The identification of the orders of phase transitions in small systems is also discussed using the density of Yang-Lee zeros.
Yang-Lee zeros of the one-dimensional Q-state Potts model
Seung-Yeon Kim
Physics , 2003, DOI: 10.3938/jkps.44.495
Abstract: The distributions of the Yang-Lee zeros of the ferromagnetic and antiferromagnetic Q-state Potts models in one dimension are studied for arbitrary Q and temperature. The Yang-Lee zeros of the Potts antiferromagnet have been fully investigated for the first time. The distributions of the Yang-Lee zeros show a variety of different shapes. Some of the Yang-Lee zeros lie on the positive real axis even for T>0. For the ferromagnetic model this happens only for Q<1, while there exist some zeros of the antiferromagnetic model on the positive real axis both for Q<1 and for Q>1.
Partition function zeros of the Q-state Potts model on the simple-cubic lattice
Seung-Yeon Kim
Physics , 2002, DOI: 10.1016/S0550-3213(02)00465-0
Abstract: The $Q$-state Potts model on the simple-cubic lattice is studied using the zeros of the exact partition function on a finite lattice. The critical behavior of the model in the ferromagnetic and antiferromagnetic phases is discussed based on the distribution of the zeros in the complex temperature plane. The characteristic exponents at complex-temperature singularities, which coexist with the physical critical points in the complex temperature plane for no magnetic field ($H_q=0$), are estimated using the low-temperature series expansion. We also study the partition function zeros of the Potts model for nonzero magnetic field. For $H_q>0$ the physical critical points disappear and the Fisher edge singularities appear in the complex temperature plane. The characteristic exponents at the Fisher edge singularities are calculated using the high-field, low-temperature series expansion. It seems that the Fisher edge singularity is related to the Yang-Lee edge singularity which appears in the complex magnetic-field plane for $T>T_c$.
Determination of phytosterols in Oryza sativa L. cultivars by liquid chromatography atmospheric chemical ionization time-of-flight mass spectrometer (LC-APCI-TOF-MS) coupled with a modified QuEChERS method  [PDF]
Seung Rok Lee, Dong Cheon Yun, Seung Ho Lee, Si Young Yang, In Seon Kim
Journal of Agricultural Chemistry and Environment (JACEN) , 2012, DOI: 10.4236/jacen.2012.11003
Abstract: Development of analytical methods for the determination of phytosterols in whole grains is one of growing interests due to their clinical and nutritional functions in human. In this study, we examined simultaneous determination of β-si tosterol, stigmasterol and campesterol in Korean rice cultivars by liquid chromatography atmospheric chemical ionization time-of-flight mass spectrometer (LC-APCI-TOF-MS). The hulled rice samples were extracted using a modified QuEChERS and analyzed by LC-APCI -TOF-MS. The method was validated by low limit of detection (LOD) and limit of quantification (LOQ) values and high recovery values with low relative standard deviation (RSD). The highest concentration of sitosterol was detected in Hwasung and Undu rice cultivars, exhibiting approximately 195.5 and 191.7 mg/Kg, respectively. Stigmasterol and campesterol were detected at the highest level in Hwasung rice cultivar, giving the concentrations of approximately 70.0 and 53.9 mg/Kg, respectively. Sitosterol was determined to be a main phytosterol detected in the rice samples. Our data demonstrated that LC/APCI-TOF- MS coupled with QuEChERS method can be used as a simple tool for the determination of phytosterols in rice samples.
Comparison of different nutritional assessments in detecting malnutrition among gastric cancer patients
Seung Wan Ryu, In Ho Kim
World Journal of Gastroenterology , 2010,
Abstract: AIM: To evaluate the prevalence of preoperative and postoperative malnutrition and the relationships between objective and subjective nutritional assessment of gastric cancer patients.METHODS: From October 2005 to July 2006, we studied 80 patients with no evidence of recurrent disease and no loss to follow-up after curative surgery for gastric cancer. In this group, 9 patients underwent total gastrectomy and 71 patients subtotal gastrectomy. At admission, 6 and 12 mo after surgery, the patients were assessed on the subjective global assessment (SGA), nutritional risk screening (NRS-2002), nutritional risk index (NRI) and by anthropometric measurements and laboratory data. Differences between the independent groups were assessed with the Student’s t test and one-way analysis of variance. Spearman’s rank correlation coefficients were calculated to evaluate the association between the scores and variables.RESULTS: The prevalence of malnutrition at admission was 31% by SGA and 43% by NRS-2002. At admission, the anthropometric data were lower in the malnourished groups defined by the SGA and NRS-2002 assessments, but did not differ between the groups using the NRI assessment. Body weight (BW), body mass index (BMI), triceps skin fold and midarm circumference were significantly reduced, but the total lymphocyte count, albumin, protein, cholesterol and serum iron levels did not decrease during the postoperative period. Six months after surgery, there was a good correlation between the nutritional assessment tools (SGA and NRS-2002) and the other nutritional measurement tools (BW, BMI, and anthropometric measurements). However, 12 mo after surgery, most patients who were assessed as malnourished by SGA and NRS-2002 had returned to their preoperative status, although their BW, BMI, and anthropometric measurements still indicated a malnourished status.CONCLUSION: A combination of objective and subjective assessments is needed for the early detection of the nutritional status in case of gastric cancer patients after gastrectomy.
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