Inhibition of S/G(2) phase CDK4 reduces mitotic fidelity

Cyclin-dependent kinase 4 (CDK4)/cyclin D has a key role in regulating progression through late G(1) into S phase of the cell cycle. CDK4-cyclin D complexes then persist through the latter phases of the cell cycle, although little is known about their potential roles. We have developed small molecule inhibitors that are highly selective for CDK4 and have used these to define a role for CDK4-cyclin D in G(2) phase. The addition of the CDK4 inhibitor or small interfering RNA knockdown of cyclin D3, the cyclin D partner, delayed progression through G(2) phase and mitosis. The G(2) phase delay was independent of ATM/ATR and p38 MAPK but associated with elevated Wee1. The mitotic delay was because of failure of chromosomes to migrate to the metaphase plate. However, cells eventually exited mitosis, with a resultant increase in cells with multiple or micronuclei. Inhibiting CDK4 delayed the expression of the chromosomal passenger proteins survivin and borealin, although this was unlikely to account for the mitotic phenotype. These data provide evidence for a novel function for CDK4-cyclin D3 activity in S and G(2) phase that is critical for G(2)/M progression and the fidelity of mitosis.

Dual affinity method for plasmid DNA purification in aqueous two-phase systems

The DNA binding fusion protein, LacI-His6-GFP, together with the conjugate PEG-IDA-Cu(II) (10 kDa) was evaluated as a dual affinity system for the pUC19 plasmid extraction from an alkaline bacterial cell lysate in poly(ethylene glycol) (PEG)/dextran (DEX) aqueous two-phase systems (ATPS). In a PEG 600-DEX 40 ATPS containing 0.273 nmol of LacI fusion protein and 0.14% (w/w) of the functionalised PEG-IDA-Cu(II), more than 72% of the plasmid DNA partitioned to the PEG phase, without RNA or genomic DNA contamination as evaluated by agarose gel electrophoresis. In a second extraction stage, the elution of pDNA from the LacI binding complex proved difficult using either dextran or phosphate buffer as second phase, though more than 75% of the overall protein was removed in both systems. A maximum recovery of approximately 27% of the pCU19 plasmid was achieved using the PEG-dextran system as a second extraction system, with 80-90% of pDNA partitioning to the bottom phase. This represents about 7.4 microg of pDNA extracted per 1 mL of pUC19 desalted lysate.

Evaluation of new processes for the preparation of iron by gas/solid phase systems

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Novel prefractionation method can be used in proteomic analysis

For the first time, a novel prefractionation method used in proteomic analysis was developed, which is performed by a novel aqueous two-phase system (NATPS) composed of n-butanol, (NH4)(2)SO4, and water. It can separate proteomic proteins into multigroups by one-step extraction. The phase-separation conditions of n-butanol solutions were studied in the presence of commonly used inorganic salts. The NATPS was subsequently developed. Using human serum albumin, zein, and gamma-globulin as model proteins, the separation effectiveness of the NATPS for protein was studied under affection factors, i.e., pH, n-butanol volume, protein, or salt concentration. The model and actual protein samples were separated by the NATPS and then directly used for gel electrophoresis without separating the target proteins from phase-forming reagents. It revealed that the NATPS could separate proteomic proteins into multigroups by one-step extraction. The NATPS has the advantages of rapidity, simplicity, low cost, biocompability, and high efficiency. It need not separate target proteins from the phase-forming reagents. The NATPS has great significance in separation and extraction of proteomic proteins, as well as in methodology.

A single cation or anion dendrimer-based liquid electrolyte

We propose here a novel liquid dendrimer-based single ion conductor as a potential alternative to conventional molecular liquid solvent-salt solutions in rechargeable batteries, sensors and actuators. A specific change from ester (-COOR) to cyano (-CN) terminated peripheral groups in generation-one poly(propyl ether imine) (G1-PETIM)-lithium salt complexes results in a remarkable switchover from a high cation (tLi+ = 0.9 for -COOR) to a high anion (tPF6- = 0.8 for -CN) transference number. This observed switchover draws an interesting analogy with the concept of heterogeneous doping, applied successfully to account for similar changes in ionic conductivity arising out of dispersion of insulator particle inclusions in weak inorganic solid electrolytes. The change in peripheral group simultaneously affects the effective ionic conductivity, with the room temperature ionic conductivity of PETIM-CN (1.9 × 10-5 Ω-1 cm-1) being an order of magnitude higher than PETIM-COOR (1.9 × 10-6 Ω-1 cm-1). Notably, no significant changes are observed in the lithium mobility even following changes in viscosity due to the change in the peripheral group. Changes in the peripheral chemical functionality directly influence the anion mobility, being lower in PETIM-COOR than in PETIM-CN, which ultimately becomes the sole parameter controlling the effective transport and electrochemical properties of the dendrimer electrolytes.

Gas-phase reactions of aryl radicals with 2-butyne : an experimental and theoretical investigation employing the N-methyl-pyridinium-4-yl radical cation

Aromatic radicals form in a variety of reacting gas-phase systems, where their molecular weight growth reactions with unsaturated hydrocarbons are of considerable importance. We have investigated the ion-molecule reaction of the aromatic distonic N-methyl-pyridinium-4-yl (NMP) radical cation with 2-butyne (CH3C CCH3) using ion trap mass spectrometry. Comparison is made to high-level ab initio energy surfaces for the reaction of NMP and for the neutral phenyl radical system. The NMP radical cation reacts rapidly with 2-butyne at ambient temperature, due to the apparent absence of any barrier. The activated vinyl radical adduct predominantly dissociates via loss of a H atom, with lesser amounts of CH3 loss. High-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry allows us to identify small quantities of the collisionally deactivated reaction adduct. Statistical reaction rate theory calculations (master equation/RRKM theory) on the NMP + 2-butyne system support our experimental findings, and indicate a mechanism that predominantly involves an allylic resonance-stabilized radical formed via H atom shuttling between the aromatic ring and the C-4 side-chain, followed by cyclization and/or low-energy H atom beta-scission reactions. A similar mechanism is demonstrated for the neutral phenyl radical (Ph center dot)+2-butyne reaction, forming products that include 3-methylindene. The collisionally deactivated reaction adduct is predicted to be quenched in the form of a resonance-stabilized methylphenylallyl radical. Experiments using a 2,5-dichloro substituted methyl-pyridiniumyl radical cation revealed that in this case CH3 loss from the 2-butyne adduct is favoured over H atom loss, verifying the key role of ortho H atoms, and the shuttling mechanism, in the reactions of aromatic radicals with alkynes. As well as being useful phenyl radical analogues, pyridiniumyl radical cations may form in the ionosphere of Titan, where they could undergo rapid molecular weight growth reactions to yield polycyclic aromatic nitrogen hydrocarbons (PANHs).

Quantum phase transitions in the S=1/2 distorted diamond chain

By means of the second derivative of the ground-state and first-excited energy, the quantum phase transitions (QPTs) for the distorted diamond chain (DDC) with ferromagnetic and antiferromagnetic frustrated interactions and the trimerized case are investigated, respectively. Our results show the plentiful quantum phases owing to the spin interaction competitions in the model. Meanwhile, by using the transfer-matrix renormalization-group technique, we study the two-site thermal entanglement of the DDC model in the thermodynamic limit for a further understanding of the QPTs.

Magnetic frustration induced quantum phase transitions in the S=1/2 vertically asymmetric diamond chain

This work was supported by the National Basic Research Program of China (973 Program) grant No. G2009CB929300 and the National Natural Science Foundation of China under Grant Nos. 60521001 and 60776061.

Steric effects on the ultraviolet absorption of 1,2-enedioic and related systems

1,2-Enedioic systems, being sterically perturbed from planarity do not show the effect of the extended conjugation expected of a (formal) trienic entity. In the absence of a model which approximates to a uniplanar situation, the strategy of replacing an ester group in the enedioates by a cyano (for which less stringent steric demand may be presumed) and noting the correction concomitant to this replacement was adopted to arrive at a notional figure for the position of maximal absorption in the planar enedioates. From this the conclusion, subject to substantiation by molecular mechanical or quantum chemical calculations, was drawn that even the E-isomeric and comparatively less substituted enedioates are highly sterically perturbed. An alternative to an earlier explanation of the bathochromic shift of absorption maxima encountered in the 5-cyclic ene-ester and ene-nitrile, relative to the 6-cyclic analogues (observed also with the enedioates and cyanovinyl ester systems), seen later to have been based on unwarranted premises, has been advanced. A comment on the absorption characteristics of enedioic anhydrides has been appended.

Two-phase Flow in Fuel Cells in Short-term Microgravity Condition

A visual observation of liquid-gas two-phase flow in anode channels of a direct methanol proton exchange membrane fuel cells in microgravity has been carried out in a drop tower. The anode flow bed consisted of 2 manifolds and 11 parallel straight channels. The length, width and depth of single channel with rectangular cross section was 48.0 mm, 2.5 mm and 2.0 mm, respectively. The experimental results indicated that the size of bubbles in microgravity condition is bigger than that in normal gravity. The longer the time, the bigger the bubbles. The velocity of bubbles rising is slower than that in normal gravity because buoyancy lift is very weak in microgravity. The flow pattern in anode channels could change from bubbly flow in normal gravity to slug flow in microgravity. The gas slugs blocked supply of reactants from channels to anode catalyst layer through gas diffusion layer. When the weakened mass transfer causes concentration polarization, the output performance of fuel cells declines.

Two-phase flow and pool boiling heat transfer in microgravity

Researches on two-phase flow and pool boiling heat transfer in microgravity, which included groundbased tests, flight experiments, and theoretical analyses, were conducted in the National Microgravity Laboratory/CAS. A semi-theoretical Weber number model was proposed to predict the slug-to-annular flow transition of two-phase gas–liquid flows in microgravity, while the influence of the initial bubble size on the bubble-to-slug flow transition was investigated numerically using the Monte Carlo method. Two-phase flow pattern maps in microgravity were obtained in the experiments both aboard the Russian space station Mir and aboard IL-76 reduced gravity airplane. Mini-scale modeling was also used to simulate the behavior of microgravity two-phase flow on the ground. Pressure drops of two-phase flow in microgravity were also measured experimentally and correlated successfully based on its characteristics. Two space experiments on pool boiling phenomena in microgravity were performed aboard the Chinese recoverable satellites. Steady pool boiling of R113 on a thin wire with a temperature-controlled heating method was studied aboard RS-22, while quasi-steady pool boiling of FC-72 on a plate was studied aboard SJ-8. Ground-based experiments were also performed both in normal gravity and in short-term microgravity in the drop tower Beijing. Only slight enhancement of heat transfer was observed in the wire case, while enhancement in low heat flux and deterioration in high heat flux were observed in the plate case. Lateral motions of vapor bubbles were observed before their departure in microgravity. The relationship between bubble behavior and heat transfer on plate was analyzed. A semi-theoretical model was also proposed for predicting the bubble departure diameter during pool boiling on wires. The results obtained here are intended to become a powerful aid for further investigation in the present discipline and development of two-phase systems for space applications.

PROBABILISTIC ESTIMATION OF THE STRUCTURE SEMINVARIANTS IN THE MONOCLINIC AND ORTHORHOMBIC SYSTEMS WHEN ANOMALOUS SCATTERERS ARE PRESENT

The estimate formulas for the two-phase structure seminvariants (TPSSs) in the presence of anomalous scattering are obtained from the estimate of the two-phase structure invariants [Hauptman (1982). Acta Cryst. A38, 632-641; Giacovazzo (1983). Acta Cryst.

Phase behavior of the orange essential oil/sodium bis(2-ethylhexyl)sulfosuccinate/water system

The ternary phase diagram for the orange essential oil (OEO)/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water system was constructed at 25 degrees C. It indicates a large single phase region, comprising an isotropic water-in-oil (W/O) microemulsion (ME) phase (L(2)), a liquid crystal (LC) (lamellar or hexagonal) and a large unstable emulsion phase that separates in two phases of normal and reverse micelles (L(1) and L(2)). In this communication the properties of the ME are investigated by viscosity, electric conductivity and small angle X-ray scattering (SAXS) indicating that the isotropic ME phase exhibits different behaviors depending on composition. At low water content low viscous ""dry"" surfactant structures are formed, whereas at higher water content higher viscous water droplets are formed. The experimental data allow the determination of the transition from ""dry"" to the water droplet structures within the L(2) phase. SAXS analyses have also been performed for selected LC samples. (C) 2009 Elsevier B.V. All rights reserved.