A Two-dimensional Lanthanide Coordination Framework with a New Amide-type Tripodal Ligand, 2,2′,2＂-Nitrilotris{[（2′- benzylaminoformyl）phenoxy]ethyl}amine

The La(III) complex with a new amide‐type tripodal ligand,2,2′.2″‐nitrilotris{[(2′‐benzylaminofomyl)‐phenoxylethyl)amine (L), was synthesized and characterized by X‐ray crystallographic analysis. Crystal data: C₄₈H_55.50LaN₇O_18.75, M_r=1169.40, monoclinic. space group, P2₁/n, a= 1.0644(3) nm. b=2.3889(5) nm, c= 2.1917(5) nm, β=90.65°, V=5.573(2) nm³, Z=1, D_c=1.394 g°cm^?3, R₁=0.0487, wR [1>2s?(I)]=0.1266. The results reveal that each La(III) ion binds to 9 oxygen atoms, three of which belong to carbonyl groups from three tripodal ligands and six to three bidentate nitrate groups and a two‐dimensional sheet of 4.8² networks is assembled by metal‐ligand coordination interaction. L, a heptadentate compound, merely acts as a tridentate bridging spacer due to its steric hindrance and links the La(III) ions as three‐connected nodes.     

Proteins Entrapped in Silica Monoliths Prepared from Glyceroxysilanes

The preparation of discrete polyol based silane precursors derived from glycerol by a simple one-pot process is described. These polyol-based silanes could be hydrolyzed under mild pH conditions and upon gelation resulted in the formation of optically clear, monolithic, mesoporous silica. The hydrolysis and condensation reactions lead to cure rates that are very sensitive to ionic strength, but are almost unaffected by pH in contrast to those of alkoxysilanes derived from primary alcohols such as Si(OEt)₄. Residual glycerol in the silica monolith could be removed by washing, or could be left in the silica to reduce the magnitude of shrinkage during long term storage. The biocompatible glyceroxysilane precursors lead to materials that were able to retain the activity of entrapped enzymes over repeated cycles of use for periods of up to several months.     

Determination of Dextromethorphan and its Metabolite Dextrorphan in Human Hair by Gas Chromatography–Mass Spectrometry

An analytical method has been developed for determination of dextromethorphan (DMP) and dextrorphan (DRP) in human hair by gas chromatography–mass spectrometry (GC–MS). Hair samples (30 mg) were washed with distilled water and acetone and cut into small fragments (<1 mm) before extraction with methanol. The extracts were evaporated to dryness and then derivatized by use of BSTFA containing 1% TMCS, for preparation of the trimethylsilyl (TMS) derivative of DRP. The extract (1 μL) was then injected into the GC–MS. Recoveries of DMP and DRP at 7.0 and 22.5 ng mg^?1 were in the range 90.6–97.2% with intra-assay and inter-assay precision of less than 5.7% and 4.7%, respectively. LOD and LOQ were, respectively, 0.67 and 2.13 ng mg^?1 for DMP and 0.14 and 0.47 ng mg^?1 for DRP. The responses were linear with correlation coefficients (r > 0.9995) for the drugs studied. The applicability of the method was proven by analysis of authentic hair samples.     

Novel photopolymerizable biodegradable triblock polymers for tissue engineering scaffolds: synthesis and characterization

For use in micro-patterned scaffolds in tissue engineering, novel diacrylated triblock macromers (PLA-b-PCL-b-PLA, PGA-b-PCL-b-PGA and PCL-b-PEO-b-PCL) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). All diacrylated polymers were designed as triblock copolymers and involved biodegradable blocks of relatively non-polar epsilon-caprolactone (CL) and polar monomers such as glycolide (GA), lactide (LA) or ethylene oxide (EO). All triblock polymers were prepared in molecular weights of a few kilo daltons via the anionic ring-opening polymerization (ROP) of the corresponding lactide, glycolide or caprolactone using stannous octoate [Sn(Oct)(2)] as catalyst. The polymers had low polydispersity indices, ranging from 1.23 to 1.56. Biodegradable polymeric networks were prepared with conversions of 72-84% via photopolymerization of the triblock diacrylated polymers with 2,2-dimethoxy-2-phenylacetophenone (DMPA) as photoinitiator. PLA-b-PCL-b-PLA copolymers crumbled easily and were not suitable for micro-patterning. PGA-b-PCL-b-PGA copolymers had higher water contact angles than PCL-b-PEO-b-PCL and were also cytocompatible with Fibroblasts 3T3.     

First principles study of the structure,electronic state,and stability of CmN2 clusters

Geometric and electronic properties of C_mN₂ (m = 1–14) clusters have been investigated by density functional theory using the hybrid B3LYP functional and the 6‐311G(d) basis set. Harmonic frequencies for these clusters are given to aid in the characterization of the ground states. These results show that C_mN₂ (m = 1–14) clusters form linear structures with D_∞h symmetry. Two N atoms favor to bond at ends in linear isomers. The chains with odd m have triplet ground states whereas the ones with even m have singlet ground states. The calculated HOMO–LUMO gaps and ionization potentials all show that the C_mN₂ (m = 1–14) clusters with even m are more stable than those with odd m, which is consistent with the observed even–odd alternation of the time‐of‐flight signal intensities. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Angiotensin II receptor blocker attenuates overexpression of vascular endothelial growth factor in diabetic podocytes

VEGF expressed in glomerular podocytes, is known to increase vascular permeability to macromolecules. Angiotensin II can stimulate the release of VEGF, and the protective effects of angiotensin II antagonist against diabetic glomerular injury suggest that the angiotensin II-induced VEGF is an important pathogenetic mechanism in the development of proteinuria during diabetic nephropathy although this mechanism is not fully understood. In this study, the changes of VEGF expression was examined in the experimental diabetic nephropathy to determine whether these changes were modified by renoprotective intervention by blockers of angiotensin II receptors. The streptozotocin- induced diabetic rats were treated with L-158,809, a blocker of angiotensin II receptors, for 12 weeks. Age-matched rats with L-158,809 served as controls. RT-PCR and immunohistochemistry were used to assess and quantify gene and protein expression of VEGF. A progressive increase in urinary protein excretion was observed in diabetic rats. Glomerular VEGF expression was significantly higher in diabetic rats than in the control groups, with a significant reduction in glomerular VEGF expression and proteinuria in L-158,809- treated diabetic rats. VEGF mRNA was also significantly higher in diabetic kidneys than in the control groups, with a significant reduction in VEGF mRNA in L-158,809-treated diabetic kidneys. These results demonstrates that VEGF expression is significantly increased in diabetic podocytes, and angiotensin II receptor antagonist attenuated these changes in VEGF expression and prevented the development of proteinuria in vivo. Attenuation of increased VEGF expression in podocytes could contribute to the renoprotective effects of angiotensin II receptor antagonists in diabetic nephropathy.     

Numerical examination of performance of some exchange-correlation functionals for molecules containing heavy elements

The performance of 17 exchange-correlation functionals for molecules containing heavy elements are numerically examined through four-component relativistic density DFT calculations. The examined functionals show the similar accuracy as they do for the molecules containing light elements only except for bond lengths. LDA and OP86 produce good results for bond lengths and frequencies but bad bond energies. Different functionals do not show much different performance for bond energies except LDA. BP86 and GP86 produce results with average accuracy while LYP does not perform well. Although encouraging results are obtained with functional B97GGA-1, other heavily parameterized and meta-GGA functionals do not produce impressive results.     

Synthesis and structural characterization of a terminal hydroxide containing alumoxane via hydrolysis of aluminum hydrides

A novel terminal hydroxide containing dinuclear alumoxane LAl(OH)OAlL(OCH=N-tBu) (3; L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) was prepared by treatment of aluminum dihydride LAlH2 (1) and tert-butyl isocyanate in the presence of trace amounts of water and alternatively from 1 and LAlH(OCH=N-tBu) (2) with water. Compound 2 was obtained from the reaction of 1 and tert-butyl isocyanate.     

Polymer-assisted, multi-step solution phase synthesis and biological screening of histone deacetylase inhibitors

The polymer-assisted solution phase synthesis (PASP) of an array of histone deacetylase (HDAc) inhibitors is described. HDAc inhibitors have considerable potential as new anti-proliferative agents. Selected compounds were shown to inhibit both human endothelial cell proliferation, and the formation of tubules (neovascularisation) in an in vitro model of angiogenesis.