Self-assembly and characterization of Ca-Al-LDH nanohybrids containing casein proteins as guest anions

Casein, a natural biopolymer contained in milk, has been successfully intercalated into a Ca-Al-LDH host structure. Synthesis was performed by rehydration of tricalcium aluminate in the presence of casein. The resulting nanohybrids were characterized by powder X-ray diffraction (XRD), elemental analysis, infrared spectroscopy (IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Further experiments revealed that the single protein strains intercalate instead of the entire casein sub micelles, which are present in milk. Additionally, the pure phospho protein fractions α- and β-casein, which make up ∼80 wt% of total casein were isolated and intercalated into the Ca-Al-LDH host structure, yielding a biopolymer-inorganic hybrid material.     

The effect of aminoalcohols (MEA, DEA and TEA) on morphological control of nanocrystalline ZnO powders and its optical properties

The potential of using encapsulation by MEA, DEA and TEA to control the morphology of ZnO powders was investigated. The crystallite and particle size decreased as a function of aminoalcohol concentration. We found that aminoalcohols can inhibit the crystal growth of ZnO along the c-axis. A steric effect by TEA more strongly influenced the formation of different ZnO shapes than did MEA and DEA. The value of the band gap was dependent on the crystallite size, particle size and particle shape.     

The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method.     

Two new variants of nonlinear inexact Uzawa algorithms for saddle-point problems

Summary. In this paper, we consider some nonlinear inexact Uzawa methods for iteratively solving linear saddle-point problems. By means of a new technique, we first give an essential improvement on the convergence results of Bramble-Paschiak-Vassilev for a known nonlinear inexact Uzawa algorithm. Then we propose two new algorithms, which can be viewed as a combination of the known nonlinear inexact Uzawa method with the classical steepest descent method and conjugate gradient method respectively. The two new algorithms converge under very practical conditions and do not require any apriori estimates on the minimal and maximal eigenvalues of the preconditioned systems involved, including the preconditioned Schur complement. Numerical results of the algorithms applied for the Stokes problem and a purely linear system of algebraic equations are presented to show the efficiency of the algorithms. Received December 8, 1999 / Revised version received September 8, 2001 / Published online March 8, 2002 RID="*" ID="*" The work of this author was partially supported by a grant from The Institute of Mathematical Sciences, CUHK RID="**" ID="**" The work of this author was partially supported by Hong Kong RGC Grants CUHK 4292/00P and CUHK 4244/01P