An Appreciation of Professor Yu-Chi Ho

Journal of Optimization Theory and Applications -     

New-generation biomedical materials: Peptide dendrimers and their application in biomedicine

Peptide dendrimers are attractive synthetic polymers and have been widely used as a new generation of biomaterials in recent years. Peptide dendrimers, as well as general dendrimers, may be synthesized to reach nano sizes, and display well-defined architectures, highly-branched structures, high density of functional terminal groups, and controllable molecular weights. On the other hand, peptide dendrimers have properties similar to proteins and some special characteristics, such as good biocompatibility, water solubility and resistance to proteolytic digestion. Due to these advantages, peptide dendrimers have received considerable attention in biomedicine. This review focuses on the development of peptide dendrimers with emphasis on their applications both in diagnostics and in therapy.     

The dielectric and leakage current behavior of CoFe2O4-BaTiO3 composite films prepared by combining method of sol-gel and electrophoretic deposition

Composite CoFe₂O₄-BaTiO₃ films were prepared by combining method of sol-gel and electrophoretic deposition. CoFe₂O₄ thick films were prepared by electrophoretic deposition method and then BaTiO₃ precursor solution was spin-coated on these thick films to obtain dense structure. X-ray diffraction indicated that the films consisted of both spinel CoFe₂O₄ and perovskite BaTiO₃ phase. Dielectric properties and leakage current conduction of the films were studied. Leakage current characterization of the films exhibits an Ohmic conduction behavior at lower electric field and space charge limited conduction behavior at higher electric field, respectively.     

Ring-Opening Polymerization of γ-(4-Vinylbenzyl)-(L)-Glutamate N-Carboxyanhydride for the Synthesis of Functional Polypeptides

Introducing various pendant functional groups and building blocks of interest to polypeptides in a highly efficient, controlled manner is crucial to access polypeptide materials with desired structures and functions. In this study, we synthesized γ-(4-vinylbenzyl)-(L)-glutamate N-carboxyanhydride (VB-Glu-NCA), which was readily obtained and purified in large quantity. VB-Glu-NCA monomer was subsequently used for the synthesis of polypeptides containing conjugation-amenable, pendant vinyl functional groups. Controlled, living polymerizations of VB-Glu-NCA were achieved by using hexamethyldisilazane (HMDS) as the initiator, catalytic amounts of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the co-catalyst, and nitrobenzene as the inhibitor of radical-induced side reactions on the vinyl group of VB-Glu-NCA. The resulting poly(γ-(4-vinylbenzyl)-(L)-glutamate) (PVBLG) gave rise to polypeptides containing pendant functional groups or moieties through various vinyl chemistries.     

Analytical and experimental studies on nonlinear characteristics of an L-shape beam structure

This paper focuses on theoretical and experimental investigations of planar nonlinear vibrations and chaotic dynamics of an L-shape beam structure subjected to fundamental harmonic excitation,which is composed of two beams with right-angled L-shape.The ordinary differential governing equation of motion for the L-shape beam structure with two-degree-of-freedom is firstly derived by applying the substructure synthesis method and the Lagrangian equation.Then,the method of multiple scales is utilized to obtain a four-dimensional averaged equation of the L-shape beam structure.Numerical simulations,based on the mathematical model,are presented to analyze the nonlinear responses and chaotic dynamics of the L-shape beam structure.The bifurcation diagram,phase portrait,amplitude spectrum and Poincare map are plotted to illustrate the periodic and chaotic motions of the L-shape beam structure.The existence of the Shilnikov type multi-pulse chaotic motion is also observed from the numerical results.Furthermore, experimental investigations of the L-shape beam structure are performed,and there is a qualitative agreement between the numerical and experimental results.It is also shown that out-of-plane motion may appear intuitively.     

A Bulk Acoustic Wave Viscosity Sensor for Determination of Lysozyme Based on Lysis of Micrococcus Lysodeikeicus

 A method for determination of lysozyme with a Bulk Acoustic Wave (BAW) viscosity sensor is presented. It is based on the bacteriolytic action of lysozyme on Micrococcus lysodeikeicus (M. lysodeikeicus) and the response of the sensor to the viscosity and density change of this process. There was a good correlation between the frequency shift and the concentration of lysozyme in the range 10–100 μg/ml. The content of lysozyme in human saliva was determined by this method and the results obtained were in good agreement with those from the conventional turbidimetric method. This method has an advantage over the conventional turbidimetric method in that the amount of sample needed is smaller, the procedure is simpler and the concentration range of the bacterium suspension which can be used in the detection was extended. Received September 11, 1998. Revision March 15, 1999.     

Synthesis of La(III), Y(III) complexes with polyglycol aldehyde-amino acid Schiff base and their high resolution solid state13C NMR spectra

La (III), Y(III) complexes wit11 diglycol aldehyde his-arginine (H₂DAAR) and tetraglycol aldehyde bislysine (H₂TALY) Schiff bases were synthesized. Thcy were characterized and formulated as La (H₂DAAR) (NO₃)₃. 6H₂0 and Y (H₂TALY) (NO₃)₃. 5H₂0 separately by elemental analyses. The obtained complexes were investigated in detail by high resolution solid state (HRSS)¹³C NMR using cross polarization, magic angle spinning (CPMAS). and total suppression of sidebands (TOSS) techniques. The results are supported by the liquid state 2D-’H-¹³C COSY NMR spectra. Some new information about the splitting peaks of¹³C for -CH = N- group and alkene carbon bands, etc. in HRSS¹³C NMR spectra are given.     

Conjugate Addition of Indole to α,β‐Unsaturated Ketones Catalyzed by Lewis Acid Immobilized on a Biorenewable Support

Sulfonated carbonaceous solid acid was prepared straightforwardly from household granulated sucrose through a one‐pot carbonization—sulfonation process. The performance of this solid Brønsted acid was tested by the 1,1‐diacylation of aldehydes. Lewis acid, such as indium chloride, was supported on sucrose‐derived carbonaceous solid acid through anion metathesis and successfully applied to the conjugate addition of indole to α,β‐unsaturated ketones.