Republic of China Military Academy
Republic of China Military Academy
Lee M.-T.,National Synchrotron Radiation Research Center |
Lee M.-T.,National Central University |
Sun T.-L.,Rice University |
Hung W.-C.,Republic of China Military Academy |
Huang H.W.,Rice University
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013
Melittin is a prototype of the ubiquitous antimicrobial peptides that induce pores in membranes. It is commonly used as a molecular device for membrane permeabilization. Even at concentrations in the nanomolar range, melittin can induce transient pores that allow transmembrane conduction of atomic ions but not leakage of glucose or larger molecules. At micromolar concentrations, melittin induces stable pores allowing transmembrane leakage of molecules up to tens of kilodaltons, corresponding to its antimicrobial activities. Despite extensive studies, aspects of the molecular mechanism for pore formation remain unclear. To clarify the mechanism, one must know the states of the melittin-bound membrane before and after the process. By correlating experiments using giant unilamellar vesicleswith those of peptide-lipidmultilayers, we found that melittin bound on the vesicle translocated and redistributed to both sides of the membrane before the formation of stable pores. Furthermore, stable pores are formed only above a critical peptide-to-lipid ratio. The initial states for transient and stable pores are different, which implies different mechanisms at low and high peptide concentrations. To determine the lipidic structure of the pore, the pores in peptide-lipid multilayers were induced to form a lattice and examined by anomalous X-ray diffraction. The electron density distribution of lipid labels shows that the pore is formed by merging of two interfaces through a hole. The molecular property of melittin is such that it adsorbs strongly to the bilayer interface. Pore formation can be viewed as the bilayer adopting a lipid configuration to accommodate its excessive interfacial area.
Chiu C.-W.,National Cheng Kung University |
Ho Y.-H.,University of Houston |
Shyu F.-L.,Republic of China Military Academy |
Lin M.-F.,National Cheng Kung University
Applied Physics Express | Year: 2014
The band structures and optical properties of AB-stacked multilayer graphene are calculated using the tight-binding model and gradient approximation. For nL-layer AB-stacked graphene, there are n2L excitation channels at both the low and middle frequencies. However, in the excitation spectra, nL (nL - 1) peaks exist at the low frequency for even-layer (odd-layer) systems, and one-shoulder and nL peaks at the middle frequency. With increasing nL, the differences in the spectra between the odd and even layers are reduced. When nL increases to 30 (50), the spectra of 2D and 3D systems are almost identical at the middle (low) frequency. © 2014 The Japan Society of Applied Physics
Lee M.-H.,Republic of China Military Academy |
Tsung-Chien Chen,Chung Cheng Institute of Technology
Structural Engineering and Mechanics | Year: 2010
The innovative intelligent fuzzy weighted input estimation method which efficiently and robustly estimates the unknown time-varying input force in on-line is presented in this paper. The algorithm includes the Kalman Filter (KF) and the recursive least square estimator (RLSE), which is weighted by the fuzzy weighting factor proposed based on the fuzzy logic inference system. To directly synthesize the Kalman filter with the estimator, this work presents an efficient robust forgetting zone, which is capable of providing a reasonable compromise between the tracking capability and the flexibility against noises. The capability of this inverse method are demonstrated in the input force estimation cases of the plate structure system. The proposed algorithm is further compared by alternating bwtween the constant and adaptive weighting factors. The results show that this method has the properties of faster convergence in the initial response, better target tracking capability, and more effective noise and measurement bias reduction.
Lih F.L.,Republic of China Military Academy
Journal of Applied Mechanics and Technical Physics | Year: 2016
The aim of the present research is to conduct a numerical study of the characteristic of a two-phase magnetorheological fluid with different operation conditions by the finite volume method called SIMPLE with an add-on MHD code. © 2016, Pleiades Publishing, Ltd.
Sung C.-K.,Republic of China Military Academy |
Lu C.-H.,Cheng Shiu University
Optik | Year: 2012
This study integrates panoramic imaging and stereo vision theory to propose an innovative 3D optical positioning method for single-camera panoramic stereo imaging systems. The conventional single-viewpoint theory based on pinhole modeling is replaced by a skew ray tracing methodology to establish the geometrical relationships of object and image. An analytical model of a single-CCD panoramic stereo imaging system is then established by adopting a catadioptric imaging system, a single-CCD stereo panoramic vision system and the presented skew ray camera calibration method. © 2011 Elsevier GmbH.
Huang T.-H.,National Cheng Kung University |
Lewis J.L.,University of Minnesota |
Lin H.-S.,National Cheng Kung University |
Lin H.-S.,National Taiwan Normal University |
And 7 more authors.
Journal of Nutrition | Year: 2014
Dietary methionine restriction (MR) has been suggested to be comparable to endurance exercise with respect to its beneficial effects on health. To further investigate the effects ofMRand endurance exercise on growing bone, 7-wk-old male Sprague-Dawley ratswere fed different L-methionine (Met)-containing diets with orwithout endurance exercise intervention (Ex; 0.86% Met, 0.52% Met, 0.17% Met, 0.86% Met-Ex, 0.52% Met-Ex, and 0.17% Met-Ex groups). After an 8-wk intervention period, exercise-trained rats had a 9.2%lower body weight (BW) than did sedentary rats (P < 0.05). Additionally, 0.17% Met-fed rats had 32% lower BW when compared with rats fed the other 2 diets (P < 0.05). Serum osteocalcin was lower in the 0.17% Met-Ex group compared with the other 2 exercise groups and the 0.17% Met group (P < 0.05). Serum concentrations of C-terminal telopeptide of type 1 collagen were lower in exercise-trained and 0.17% Met-fed rats than in sedentary rats and rats fed the other 2 diets (P < 0.05 for both). Rats fed the 0.17% Met diet had lower trabecular bone volume, bone mineralization activities, and bone mineral content (BMC; e.g., total, cortical, and spongy BMC) and bone mineral density (BMD; e.g., total and spongy BMD) indices compared with rats fed the other 2 diets (P < 0.05). Exercisetrained rats also had lower bonemineralization activity, trabecular osteoclast density, total BMC, cortical BMC, and total BMD compared with sedentary rats (P < 0.05). In total BMD, only the 0.17% Met-Ex group had values lower than the other 2 exercise groups and the 0.17%Met group (P < 0.05). Comparedwith rats fed the other 2 diets and sedentary rats, the femora of 0.17% Met-fed and exercise-trained rats, respectively, had smaller size and/or lower extrinsic strength but enhanced intrinsic biomechanical properties (P < 0.05). The results indicate that MR and endurance exercise caused lower whole bone mass, size, and/or strength but might enhance intrinsic bone strength. © 2014 American Society for Nutrition.
Lu C.-H.,Cheng Shiu University |
Sung C.-K.,Republic of China Military Academy
Optik | Year: 2013
One of the most popular mathematical tools in fields of robotics, mechanisms and computer graphics is the 4 × 4 homogeneous transformation matrix. Our group's previous application of the homogeneous transformation matrix to flat and spherical optical boundaries has been extended to hyperboloid surfaces for: (1) skew ray tracing to determine the paths of reflected/refracted skew rays; (2) sensitivity analysis for direct mathematical expression of differential changes of incident points and reflected/refracted vectors with respect to changes in incident light sources and boundary geometric parameters; (3) a sensitivity analysis-based merit function derived directly from mathematical expression of catadioptric imaging system components. The presented methodology is highly suited to digital implementation and offers direct and rapid analytical statement of ray path, chief ray, marginal rays and merit functions of optical systems. © 2012 Elsevier GmbH.
Sung C.-K.,Republic of China Military Academy |
Lu C.-H.,Cheng Shiu University
Journal of Mechanical Science and Technology | Year: 2014
Four-half axis and five-axis machine tools have five moving members (X, Y, Z, A, and B). Four-half axis systems cannot simultaneously operate the B axis with translational or rotational axes, thus limiting tool machining ability and complicating NC codes. This study employs modified Denavit-Hartenberg notation to model four-half axis machine tool kinematics and obtain corresponding ability matrixes. NC data equations for the A, B, X, Y, and Z axes with respect to the workpiece frame are derived by inverse kinematics. Machine tool active parameters and workpiece home position are simultaneously measured by using a ball-end milling cutter as a measuring probe. © 2014, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.
PubMed | National Synchrotron Radiation Research Center, Republic of China Military Academy and Rice University
Type: Journal Article | Journal: Biophysical journal | Year: 2016
Cholesterol, due to its condensing effect, is considered an important regulator of membrane thickness. Other sterols, due to their structural similarities to cholesterol, are often assumed to have a universal effect on membrane properties similar to the condensing effect of cholesterol, albeit possibly to different degrees. We used x-ray diffraction to investigate this assumption. By the combination of lamellar diffraction and grazing-angle scattering, we measured the membrane thickness and the tilt-angle distribution of the lipids hydrocarbon chains. This method is sensitive to phase separation, which is important for examining the miscibility of sterols and phospholipids. Mixtures of ergosterol or cholesterol with dimyristoylphosphatidylcholine, palmitoyloleoylphosphatidylcholine, and dioleoylphosphatidylcholine were systematically studied. We found that mixing ergosterol with phospholipids into a single phase became increasingly difficult with higher sterol concentrations and also with higher concentrations of unsaturated lipid chains. The only condensing effect of ergosterol was found in dimyristoylphosphatidylcholine, although the effect was less than one-third of the effect of cholesterol. Unlike cholesterol, ergosterol could not maintain a fixed electron density profile of the surrounding lipids independent of hydration. In dioleoylphosphatidylcholine and palmitoyloleoylphosphatidylcholine, ergosterol made the membranes thinner, opposite to the effect of cholesterol. In all cases, the tilt-angle variation of the chain diffraction was consistent with the membrane thickness changes measured by lamellar diffraction, i.e., a thickening was always associated with a reduction of chain tilt angles. Our findings do not support the notion that different sterols have a universal behavior that differs only in degree.
PubMed | National Cheng Kung University, Republic of China Military Academy, National Pingtung University and National Kaohsiung Marine University
Type: | Journal: Scientific reports | Year: 2017
The feature-rich electronic excitations of monolayer germanene lie in the significant spin-orbit coupling and the buckled structure. The collective and single-particle excitations are diversified by the magnitude and direction of transferred momentum, the Fermi energy and the gate voltage. There are four kinds of plasmon modes, according to the unique frequency- and momentum-dependent phase diagrams. They behave as two-dimensional acoustic modes at long wavelength. However, for the larger momenta, they might change into another kind of undamped plasmons, become the seriously suppressed modes in the heavy intraband e-h excitations, keep the same undamped plasmons, or decline and then vanish in the strong interband e-h excitations. Germanene, silicene and graphene are quite different from one another in the main features of the diverse plasmon modes.