Mong Liang

A simple and direct isolation of whey components from raw milk by gel filtration chromatography and structural characterization by Fourier transform Raman spectroscopy

A simple and economical method to isolate whey protein from fresh raw milk is developed by serial defatting, casein eliminating, lactose removing, and separating by gel filtration chromatography. Four major whey components, including immunoglobulin (Ig), bovine serum albumin (BSA), beta-lactoglobulin (beta-Lg) and alpha-lactalbumin (alpha-Lac), and a non-protein of low molecular mass ( approximately 1.7 kDa) but strong absorbance at 280 nm, are detected simultaneously. The small non-protein molecule is rich in aromatic amino acids and thiol groups as supported by the structural characterization with near infrared Fourier transform Raman spectroscopy (FT-Raman). FT-Raman results show that the secondary structure of Ig is dominated by anti-parallel beta-pleated sheet; BSA is mainly in alpha-helix; both beta-form and unordered structure are important in beta-Lg; while alpha-Lac is mostly in alpha-helix coupling with random coil. Differences in the Raman profile for each whey component reflect their intrinsic compositional differences and distinct spatial arrangement. The S-S linkages diverging around 510-540 cm(-1) indicate that the conformation of disulfide bonds in each whey components is different, which may be responsible for their diversified behaviors in solubility, rheological and functional properties.

Synthesis and reactivity of the α-β-unsaturated carbene tungsten complex (CO)5W[C(OCH)3)CHCH2]

Abstract Treatment of W(CO) 6 with vinyllithium followed by Me 3 OBF 4 in the presence of H 2 O produced (CO) 5 W[C(OCH 3 )CHCH 2 ] ( 1 ) (25–30%) and (CO) 5 W[C(OCH 3 )-(η-CHCH 2 )]W(CO) 5 ( 2 ) (20–30%). Complex 1 reacted with (CO) 5 W · THF to give W 2 (CO) 9 [μ-μ 1 ,η 3 -C(OCH 3 )CHCH 2 ] ( 3 ) (61%). Heating 2 to 45°C in toluene produced 3 (65%) which could be converted back to 2 upon treatment with CO. Complex 1 reacte with D 2 O in benzene- d 6 to afford 2 and methyl propionate-2,3- d 2 ( 4 ). A new route to 1 was developed from C(CO) 6 in an overall yield of 40% using (CO) 5 W[C(O)CHCH 2 ]NME 4 ( 8 ) as an intermediate.

Rings, Polymers, and New Materials Containing Phosphorus and Other Main Group Main Elements or Transition Metals

Abstract Polymers which contain inorganic elements are attracting considerable attention because they provide access to materials with interesting, unusual and potentially useful properties. In this paper we emphasize some of our recent work aimed at exploiting ring-opening polymerization as a route to new inorganic and organometallic polymers containing the main group element phosphorus. For example, attempts to prepare new polymers which also contain boron are reported. In addition, recent results on the ring-opening polymerization of [1]- metallocenophanes such as cyclic ferrocenylsilanes and cyclic ferrocenylphosphines, which possess strained ring-tilted structures, are described. Finally, some recent research on poly(thionylphosphazenes), a novel class of inorganic polymers with sulphur(VI)-nitrogen-phosphorus backbones, is discussed.

Crystal structure of a (μ-bis(carbene))dimetal complex of tungsten

The (μ-bis(carbene))ditungsten complex, (CO)5W{(C(OCH2Ph)C(CH2C2H3)(Me)CH2CH2C(OCH2Ph)}W(CO)5 (1) is only the fifth such complex to be crystallographically characterized. The steric demands of one side of the bis(carbene) ligand gives rise to small, but statistically significant differences in the bonding parameters to W. The W=C distances are 2.195(4) and 2.171(6)Å. The carbonyltrans to the longest W=C bond has the shortest of the ten W-CO separations (1.994(5)Å) and the longest C≡O bond length (1.156(6)Å). The planes defined by the two carbene groups have a dihedral angle of 44.5°.

Ring-Opening Polymerization as a Route to New Inorganic Macromolecules

Abstract Cyclic inorganic compounds are potential precursors to new inorganic polymer systems via ring-opening polymerization. In this paper we review some of our recent work aimed at preparing inorganic polymers containing main group elements. For example, the ring-opening polymerization of the cyclic thionylphosphazenes NSOX(NPCl2)2 (X = Cl or F) is discussed. This provides a route to poly(thionylphosphazenes), a new class of stable inorganic polymers with backbones of phosphorus, nitrogen, and sulfur(V1) atoms. We also describe some of our preliminary work aimed at the investigation of the synthesis, structure, and polymerization behaviour of boracyclosiloxanes (RBO)(R2SiO)n.