Atomic force microscopy measurement of the elastic properties of the kidney epithelial cells

Direct interaction force measurements using atomic force microscopy (AFM) were carried out between a silicon nitride tip and renal epithelial cells (Madin-Darby Canine Kidney-MDCK and proximal tubular epithelial cells derived from pig kidneys, LLC-PK1). The approaching (extending) portion of the force/distance curves is considered, and repulsive forces in the long range of 2-3 microm were seen in both MDCK as well as LLC-PK1 cells growing under normal conditions. The repulsive force in the shorter distance range of 50-200 nm was also observed, when cells were damaged exposing the underlying basal membrane. LLC-PK1 cells were more prone to damage than the MDCK cells, hence short-range forces were common in the former and long-range forces in the latter cells. The functional dependence of repulsive force on the indentation depth changes, at small indentation depth the force increases linearly, while at larger indentations the force is a quadratic function of the distance, which is attributed to the elasticity of the membrane and the solid-like response of cells, respectively. The oxalate treatment of cells for 2-4 h gives rise to an increase in the elastic modulus of the cells.     

Reactions of 2-aminooxazoles and 2-aminothiazoles with dienophiles. Isolation of stable diels-alder adducts

Room temperature reaction of 2-aminooxazole 1 and its 4- and 4,5-substituted derivatives, with dimethyl acetylenedicarboxylate gave good yields of Diels-Alder adducts 2 , isolated as stable crystalline compounds. A competing process produced oxazole[3,2-a]pyrimidines 3 , also in good yield. Minor products were also identified. 2-Amino-4-methylthiazole ( 6 ) reacted in a similar manner and gave the Diels-Alder adduct 7 and a thia-zolo[3,2-a]pyrimidine 8 as main products with a lesser amount of a thiazole [3,2-d][1:3]diazepine ( 9 ). The aminooxazoles reacted with olefinic dienophiles to give pyridine derivative, formed by breakdown of the original unstable adducts.     

Identification and characterization of active and inactive species for surface-enhanced resonance Raman scattering

The surface-enhanced resonance Raman scattering (SERRS) activity of a statistically significant number of silver nanoparticles has been studied using a correlated SERRS mapping and transmission electron microscopy (TEM) method. TEM allowed the nature of each entity to be directly identified, and the SERRS activity was obtained from the corresponding SERRS map. Particles in various states of aggregation were analyzed to establish relative activities. It was established that SERRS activity is dependent on the specific batch of colloid tested. By averaging different colloid batches, it was shown that increasing SERRS activity is observed with increasing numbers of particles in the aggregates. By reducing the surface coverage of the particles to the extent that single moieties could be examined optically, the ratio of the relative activities of single particles, dimers, trimers, and larger aggregates was estimated. High-resolution TEM images of a number of active and inactive particles are reported. However, no clear correlation between microstructure and SERRS activity was observed.     

Synthesis of cross linked platinum metal containing polyyne polymers

Reaction of Pt(PⁿBu₃)₂Cl₂ (1) or Pt(AsⁿBu₃₂Cl₂ (2) with stoichiometric amounts of 1,3,5-triethynylbenzene, [1,3,5-(H? C?C? )₃C₆H₃] (3)yields monomeric, [1,3,5-Cl(PⁿBu₃)₂(Pt? C? C? )₃C₆H₃] (4), [1,3,5-(C1)(AsⁿBu₃)₂Pt? C? C? ₃C₆H₃] (5) or polymeric, {1,3,5-[(PⁿBu₃)₂Pt? C?C? ]₃C₆H₃? )ⁿ (6), {1,3,5-[(AsⁿBu₃)₂Pt? C? C? ]₃C₆H₃? }ⁿ (7) complexes. Treatment of (1) with (3) and 2,5-diethynyl-p-xylene,H? C? C? C₆H₂(CH₃)₂? C? C? H (8) in varying molar ratios yields a series of high molecular weight cross linked platinum metal containing polyyne copolymers.     

Supramolecular copper hydroxide tennis balls: self-assembly, structures, and magnetic properties of octanuclear [Cu(8)L(8)(OH)(4)](4+) clusters (HL = N-(2-pyridylmethyl)acetamide)

The self-assembly of supramolecular copper "tennis balls" that possess unusual magnetic properties using a small pyridyl amide ligand is described. Copper(II) complexes of N-(2-pyridylmethyl)acetamide (HL) were synthesized in methanol. In the absence of base, the mononuclear complex [Cu(HL)(2)](ClO(4))(2) (1) was prepared. The structure of 1, determined by X-ray crystallography, contains a copper(II) ion surrounded by bidentate HL ligands coordinated via the pyridyl N atom and the carbonyl O atom in a trans, square planar arrangement. Reactions carried out in the presence of triethylamine resulted in cluster complexes [Cu(8)L(8)(OH)(4)](ClO(4))(4) and [Cu(8)L(8)(OH)(4)](CF(3)SO(3))(4) [2(ClO(4))(4) and 2(OTf)(4), respectively]. The cationic portions of 2(ClO(4))(4) and 2(OTf)(4) are isostructural, containing eight copper(II) ions, eight deprotonated ligands (L(-)), and four mu(3)-hydroxide ligands. The top and bottom halves of the cluster are related by a pseudo-S(4) symmetry operation and are held together by bridging L(-) ligands. Solutions of 2(ClO(4))(4) and 2(OTf)(4), which were shown to contain the full [Cu(8)L(8)(OH)(4)](4+) fragment by electrospray mass spectrometry and conductance experiments, are EPR silent. Magnetic susceptibility measurements for 2(ClO(4))(4) as a function of temperature and magnetic field showed the Cu ions all to exhibit magnetic moments in the range expected for the d(9) configuration. At low temperatures, the magnetization was reduced due to predominantly antiferromagnetic interactions between ions. Analysis showed that partially frustrated interactions among the four Cu ions making up each half of the cluster gave good agreement with the data once a large molecular anisotropy was taken into account, with J(c) = 106 cm(-1), D = 27 cm(-1), and g = 2.17.     

Synthesis, physico-chemical and thermal characteristics of seven and ten coordinated complexes of trivalent lanthanides derived from 4[N-(cinnamalidene)amino]antipyrine semicarbazone and diphenyl sulfoxide

In present studies a new series of twenty four complexes of seven and ten coordinated compounds derived from 4[Ncinnamalidene) amino]antipyrine semicarbazone (CAAPS) as primary ligand and diphenyl sulfoxide (DPSO) as secondary ligand has been reported. All the complexes have the general composition LnX_3.n(CAAPS).DPSO (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy or Ho, X = NCS or ClO₄, n = 2, X = NO₃, n = 1). The compounds have been characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectra. Thermal characteristics were also reported. Based on the data appropriate structures are assigned for these complexes.     

Study of the excited 0+ states through conversion electron spectroscopy of neutron rich Zr and Mo fission products

A windowless Si(Li) electron detector has been used in conjunction with the gas filled fission product separator JOSEF to study totally converted transitions in Zr and Mo isotopes. The existence of twoβ-decay modes in⁹⁶Y,⁹⁸Y and¹⁰⁰Nb is confirmed. The half-lives of theβ-decaying levels feeding O ₂ ⁺ states in⁹⁶Zr and⁹⁸Zr are 6.0 ± 0.4 sec and 0.60±0.05 sec respectively. A search for other first excited O ₂ ⁺ states shows that no such states are apparent in¹⁰⁰Zr and¹⁰⁴Mo.     

Asymmetric Epoxidation of Non-Functionalized Alkenes Using Transition Metal Complexes

Asymmetric catalytic epoxidation of alkenes such as styrenes, chromenes and indene using transition metal complexes both inhomogeneous and heterogeneous phase has been discussed in this review. The various strategies to make the catalysts recyclable by introducing in-built phase transfer ability, converting these to dimeric form, exchanging into clays and supporting on polymeric or inorganic supports are discussed at length.     

Kinetic evidence for the occurrence of kinetically detectable intermediates in the cleavage of N‐ethoxycarbonylphthalimide under N‐methylhydroxylamine buffers

The kinetics of the aqueous cleavage of N‐ethoxycarbonylphthalimide (NCPH) in CH₃NHOH buffers of different pH reveals that the cleavage follows the general irreversible consecutive reaction path NCPH ENMBC A B , where ENMBC, A , and B represent ethyl N‐[o‐(N‐methyl‐N‐hydroxycarbamoyl)benzoyl]carbamate, N‐hydroxyl group cyclized product of ENMBC, and o ‐(N‐methyl‐N‐hydroxycarbamoyl)benzoic acid, respectively. The rate constant k_{1 obs} at a constant pH, obeys the relationship k_{1 obs} = k_w + k_n^app [Am]_T + k_b[Am]_T², where [Am]_T is the total concentration of CH₃NHOH buffer and k_w is first‐order rate constant for pH‐independent hydrolysis of NCPH. Buffer‐dependent rate constant k_b shows the presence of both general base and general acid catalysis. Both the rate constants k_{2 obs} and k_{3 obs} are independent of [Am]_T (within the [Am]_T range of present study) at a constant pH and increase linearly with the increase in a_OH with definite intercepts. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 95–103, 2002