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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There are highly sensitive analytical techniques for probing cellular and molecular events in very small volumes. The development of microtools for effective sample handling and separation in such volumes remains a challenge. Most devices developed so far use electrophoretic and chromatographic separation methods. We show that forces generated by ac fields under conditions of negative dielectrophoresis (DEP) can also be used. Miniaturized electrode arrays are housed in a microchannel and driven with high-frequency ac. A laminar liquid flow carries particles past the electrodes. Modification of the ac drive changes the particle trajectories. We have handled latex particles of micrometer size and living mammalian cells in a device which consists of the following four elements: a planar funnel which concentrates particles from a 1-mm-wide stream to a beam of about 50-micron width, an aligner which narrows the beam further and acts to break up particle aggregates, a field cage which can be used to trap particles, and a switch which can direct particles into one of two output channels. The electrodes are made from platinum/titanium and indium tin oxide (ITO) on glass substrates. Particle concentration and switching could be achieved for linear flow velocities up to about 10 mm s-1. The combination of this new method with high-performance optical detection offers prospects for miniaturized flow cytometry.
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PMID:Dielectrophoretic sorting of particles and cells in a microsystem. 959 86

The novel dimeric compounds [Ph(2)Sb(O(2)PR(2))O](2).2CH(2)Cl(2) [R = cycl-C(6)H(11) (2) and cycl-C(8)H(15) (3)] have been synthesized by reacting diphenylantimony trichloride (1) with 3 mol equiv of silver acetate followed by 1 mol equiv of the phosphinic acid. By the same route under more stringent conditions to exclude moisture, the mixed phosphinate-acetate [Ph(2)Sb(O(2)P(C(6)H(11))(2))(O(2)CMe)](2)O (4) was isolated and characterized. Treatment of 2 with acetic acid/water affords the tetranuclear cage Ph(8)Sb(4)O(4)(OH)(2)(O(2)P(C(6)H(11))(2))(2).CH(3)COOH.CH(2)Cl(2) (5); it is possible to convert 5 to 2 by heating it with an excess of the phosphinic acid. Compounds 2, 3, and 5 have been characterized by X-ray structural analysis. All of them possess four membered Sb(2)O(2) rings with hexacoordinated antimony. In 5 the antimony atoms in the two Sb(2)O(2) rings are connected by oxo bridges on two sides to give an Sb(4)O(6) cage. These structures are correlated with those of known tin cages.
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PMID:Dinuclear and Tetranuclear Cages of Oxodiphenylantimony Phosphinates: Synthesis and Structures. 1166 23

Tin disulfide pellets were laser ablated in an inert gas atmosphere, and closed cage fullerene-like (IF) nanoparticles were produced. The nanoparticles had various polyhedra and short tubular structures. Some of these forms contained a periodic pattern of fringes resulting in a superstructure. These patterns could be assigned to a superlattice created by periodic stacking of layered SnS(2) and SnS. Such superlattices are reminiscent of misfit layer compounds, which are known to form tubular morphologies. This mechanism adds up to the established mechanism for IF formation, namely, the annihilation of reactive dangling bonds at the periphery of the nanoparticles. Additionally, it suggests that one of the driving forces to form tubules in misfit compounds is the annihilation of dangling bonds at the rim of the layered structure.
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PMID:Synthesis of SnS2/SnS fullerene-like nanoparticles: a superlattice with polyhedral shape. 1292 73

Reaction of the lithium salt of 1-(2'-pyridyl)-ortho-carborane, Li[1-R-1,2-C(2)B(10)H(10)](R = 2'-NC(5)H(4)), with sulfur, followed by hydrolysis, gave the mercapto-o-carborane, 1-R-2-SH-1,2-C(2)B(10)H(10) which forms chiral crystals containing helical chains of molecules linked by intermolecular S-H...N hydrogen bonds. The cage C(1)-C(2) and exo C(2)-S bond lengths (1.730(3) and 1.775(2)[Angstrom], respectively) are indicative of exo S=C pi bonding. The tin derivative 1-R-2-SnMe(3)-1,2-C(2)B(10)H(10), prepared from Li[1-R-1,2-C(2)B(10)H(10)] and Me(3)SnCl, crystallises with no significant intermolecular interactions. The pyridyl group lies in the C(1)-C(2)-Sn plane, oriented to minimise the NSn distance (2.861(3)[Angstrom]). The tin environment is distorted trigonal bipyramidal with axial N and Me. The gold derivative 1-R-2-AuPPh(3)-1,2-C(2)B(10)H(10), prepared from Li[1-R-1,2-C(2)B(10)H(10)] and AuCl(PPh(3)), reveals no NAu interaction in its crystal structure.
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PMID:Sulfur, tin and gold derivatives of 1-(2'-pyridyl)-ortho-carborane, 1-R-2-X-1,2-C2B10H10 (R = 2'-pyridyl, X = SH, SnMe3 or AuPPh3). 1554 Jan 24

Although Si or Ge is not known to form empty cage clusters such as the fullerenes, we recently found a unique 12-atom icosahedral tin cluster, Sn12 2- (stannaspherene). Here we report photoelectron spectroscopy and theoretical evidence that Pb12 2- is also a highly stable icosahedral cage cluster and bonded by four delocalized radial pi bonds and nine delocalized on-sphere sigma bonds from the 6p orbitals of the Pb atoms. Following Sn12 2-, we coin a name, plumbaspherene, for the highly stable and nearly spherical Pb12 2- cluster, which is expected to be stable in solution and the solid state. Plumbaspherene has a diameter of approximately 6.3 A with an empty interior volume large enough to host most transition metal atoms, affording a new class of endohedral clusters.
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PMID:Pb12 2-: plumbaspherene. 1692 3

Six robust intermetallic compounds with cations in three different tunnel-like structures have been synthesized in alkali-metal-Au-In systems via high-temperature solid-state methods and characterized by X-ray diffraction: AAu(4)In(6) [A = K (I), Rb (II), P6m(2), Z = 1], K(1.76(6))Au(6)In(4) (III, I4/mcm, Z = 4), and A(x)Au(2)In(2) [x approximately 0.7, A = K (IV), Rb (V), Cs (VI), P4(2)/nmc, Z = 8]. The first type is constructed from a single cage unit: an alkali-metal-centered 21-vertex polyhedron A@Au(9)In(12) with 6-9-6 arrangement of planar rings. The others contain uniaxial arrays of tunnels built of differently puckered eight- and four-member Au/In rings. The largely different cation distributions depend on the tunnel constitutions and cation sizes. Tight-binding electronic structure calculations by linear muffin-tin-orbital (LMTO) methods were performed for I and idealized III in order to help understand their chemical bonding. These also reveal large differences in relativistic effects for Au d orbitals, as well as for different Au sites in each structure.
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PMID:Different cation arrangements in Au-In networks. Syntheses and structures of six intermetallic compounds in alkali-metal-Au-In systems. 1758 Sep 37

Photorelease of caged Ca(2+) is a uniquely powerful tool to study the dynamics of Ca(2+)-triggered exocytosis from individual cells. Using photolithography and other microfabrication techniques, we have developed transparent microchip devices to enable photorelease of caged Ca(2+), together with electrochemical detection of quantal catecholamine secretion from individual cells or cell arrays as a step towards developing high-throughput experimental devices. A 100 nm thick transparent indium-tin-oxide (ITO) film was sputter-deposited onto glass coverslips, which were then patterned into 24 cell-sized working electrodes (approximately 20 microm by 20 microm). We loaded bovine chromaffin cells with acetoxymethyl (AM) ester derivatives of the Ca(2+) cage NP-EGTA and Ca(2+) indicator dye fura-4F, then transferred these cells onto the working ITO electrodes for amperometric recordings. Upon flash photorelease of caged Ca(2+), a uniform rise of [Ca(2+)](i) within the target cell leads to quantal release of oxidizable catecholamines measured amperometrically by the underlying ITO electrode. We observed a burst of amperometric spikes upon rapid elevation of [Ca(2+)](i) and a "priming" effect of sub-stimulatory [Ca(2+)](i) on the response of cells to subsequent [Ca(2+)](i) elevation, similar to previous reports using different techniques. We conclude that UV photolysis of caged Ca(2+) is a suitable stimulation technique for higher-throughput studies of Ca(2+)-dependent exocytosis on transparent electrochemical microelectrode arrays.
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PMID:Controlled on-chip stimulation of quantal catecholamine release from chromaffin cells using photolysis of caged Ca2+ on transparent indium-tin-oxide microchip electrodes. 1809 74

Synergistic studies of bismuth doped tin clusters combining photoelectron spectra with first principles theoretical investigations establish that highly charged Zintl ions, observed in the condensed phase, can be stabilized as isolated gas phase clusters through atomic substitution that preserves the overall electron count but reduces the net charge and thereby avoids instability because of coulomb repulsion. Mass spectrometry studies reveal that Sn(8)Bi(-), Sn(7)Bi(2)(-), and Sn(6)Bi(3)(-) exhibit higher abundances than neighboring species, and photoelectron spectroscopy show that all of these heteroatomic gas phase Zintl analogues (GPZAs) have high adiabatic electron detachment energies. Sn(6)Bi(3)(-) is found to be a particularly stable cluster, having a large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap. Theoretical calculations demonstrate that the Sn(6)Bi(3)(-) cluster is isoelectronic with the well know Sn(9)(-4) Zintl ion; however, the fluxionality reported for Sn(9)(-4) is suppressed by substituting Sn atoms with Bi atoms. Thus, while the electronic stability of the clusters is dominated by electron count, the size and position of the atoms affects the dynamics of the cluster as well. Substitution with Bi enlarges the cage compared with Sn(9)(-4) making it favorable for endohedral doping, findings which suggest that these cages may find use for building blocks of cluster assembled materials.
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PMID:Effect of charge and composition on the structural fluxionality and stability of nine atom tin-bismuth Zintl analogues. 1895 Jan 51

Endohedral clusters, formed by incorporating a single Mn atom into a cage of tin atoms, have been generated in the gas phase. Mass spectrometry reveals that a cage size of 10 tin atoms is necessary for the efficient incorporation of one Mn atom. Some of the cluster compounds with one Mn atom attached to the tin clusters display large intensities compared to the pure tin clusters, indicating that the compound clusters are particularly stable. The manganese-doped tin cluster assemblies Mn@Sn12, Mn@Sn13, and Mn@Sn15 have been further analyzed within a molecular beam magnetic deflection experiment. Interestingly, although the effect of the magnetic field on the behavior of Mn@Sn12 is quite different from that of Mn@Sn13 and Mn@Sn15, the magnetic dipole moments are the same within the uncertainty of the measurements. Magnetic dipole moments have been found in close agreement with the spin quantum number S = 5/2 predicted by theory for Mn@Sn12, indicating that the magnetic moment of the Mn atom is not quenched. This supports the idea that within a tin cluster cage a single Mn atom can be encapsulated, resulting in the formation of endohedral clusters consisting of a central Mn2+ ion surrounded by a particularly stable Zintl-ion cage Sn(N)(2-). The observed molecular beam profiles indicate that at a nozzle temperature of 55 K the magnetic moment is strongly locked to the molecular framework of Mn@Sn12; in contrast, the magnetic moment of Mn@Sn13 and Mn@Sn15 tends to align with the magnetic field. The experiments therefore demonstrate that the size of a presumably nonmagnetic cluster cage might have a fundamental influence on the magnetization dynamics of paramagnetic species. The influence of vibrational excitation on the Stern-Gerlach profile of Mn@Sn12 is further analyzed, and it is shown that the behavior of Mn@Sn12 at elevated nozzle temperatures changes continuously toward a nonlocked moment, pointing to size- and temperature-dependent magnetization dynamics.
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PMID:Size- and temperature-dependent magnetic response of molecular cage clusters: manganese-doped tin clusters. 1986 31

The room-temperature reactions of Sn(NMe(2))(2) with less sterically demanding primary phosphines (RPH(2)) give the homoleptic phosphanediide compounds [SnPR](n) in high yields (R=tBu (1a), cyclohexyl (1b), 1-adamantyl (1c)). However, the room-temperature reaction of Mes*PH(2) (Mes*=2,4,6-tBu(3)C(6)H(2)) with Sn(NMe(2))(2) gives the model intermediate [{SnPMes*}(2)(mu-NMe(2))SnP(H)Mes*] (3), together with the product of complete deprotonation [SnPMes*](3) (4). Phosphorus--phosphorus bonded products are produced in these reactions at elevated temperatures. If the reaction producing 1a is heated to reflux then [tBuP(H)P(H)tBu] is produced as the major product (together with tin metal). The novel octanuclear cage [{SnPtBu}(7)Sn(PtBu)(3)] (2) can also be isolated in low yield, resulting from formal addition of the heterocyclic stannylene [(tBuP)(3)Sn] to a Sn-P single bond of the intact structure of 1a. Prolonged heating of the reaction producing 3 and 4 leads to the formation of the diphosphene [PMes*](2) (5) and tin metal. The X-ray structures of the heptamer 1a (n=7), octanuclear 2 and trinuclear 3 are reported.
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PMID:Formation and rearrangement of Sn(II) phosphanediide cages. 2058 56


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