Miniaturized Sequencing Gel System for Quick Analysis of DNA by Hydroxyl Radical Cleavage

We described a simple and quick miniaturized sequencing gel system for DNA analysis. Two major modifications were made to the previously reported miniaturized DNA sequencing gel system to achieve high-resolution hydroxyl radical cleavage analysis: including formamide in the miniaturized gel and providing uniform heating during electrophoresis. Our method enables one to reduce the cost for chemicals and to significantly reduce electrophoresis time. Furthermore, minimal gel handling simplifies the entire process. We show that the resolution of DNA fragments obtained by hydroxyl radical cleavage for the miniaturized gel is similar to that of a large conventional sequencing gel.     

Pressure-Suppressed Carrier Trapping Leads to Enhanced Emission in Two-Dimensional Perovskite (HA)2(GA)Pb2I7

A remarkable PL enhancement by 12 fold is achieved using pressure to modulate the structure of a recently developed 2D perovskite (HA)₂(GA)Pb₂I₇ (HA=n-hexylammonium, GA=guanidinium). This structure features a previously unattainable, extremely large cage. In situ structural, spectroscopic, and theoretical analyses reveal that lattice compression under a mild pressure within 1.6 GPa considerably suppresses the carrier trapping, leading to significantly enhanced emission. Further pressurization induces a non-luminescent amorphous yellow phase, which is retained and exhibits a continuously increasing band gap during decompression. When the pressure is released to 1.5 GPa, emission can be triggered by above-band gap laser irradiation, accompanied by a color change from yellow to orange. The obtained orange phase could be retained at ambient conditions and exhibits two-fold higher PL emission compared with the pristine (HA)₂(GA)Pb₂I₇.     

Synthesis and properties of fluorine tail-terminated cyanobiphenyls and terphenyls for chemoresponsive liquid crystals

ABSTRACT

A series of fluorine tail-terminated alkoxy and alkyl cyanobiphenyl compounds and some cyano-p-terphenyl derivatives were synthesised and mesogenic properties described. Comparison with the non-fluorinated K series and M series indicates that the terminal fluorine atom generally decreases the transition temperatures and, more interestingly, depresses the formation of a smectic phase. Several binary LC mixtures formed by the fluorine tail-terminated compounds were found exhibiting promising room temperature nematic phases with wide ranges. The mixture F7OCB and F8OCB shows homeotropic ordering at the metal salts-decorated surfaces and planar ordering at the free surface, which may have potential application in designing a more sensitive and faster LC system to targeted analytes.     

DIC Challenge 2.0: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses

Experimental Mechanics - The DIC Challenge 2.0 follows on from the work accomplished in the first Digital Image Correlation (DIC) Challenge Reu et al. (Experimental Mechanics 58(7):1067, 1). The...     

Pathways of Enzymatic Phosphotransfer Reactions

Abstract

Mevalonate 5-pyrophosphate (MVAPP) decarboxylase catalyzes the decarboxylation of MVAPP to isopentenyl pyro-phosphate, an ATP-dependent process in which 3-phospho-MVAPP is a transient intermediate that undergoes concomitant decarboxylation and elimination of phosphate. Reaction of (S_p)-adenosine 5′-0-3-thio [3-17_{O 2},180] triphosphate in place of ATP produces (R)-[17O,18O] thiophosphate in place of phosphate. Therefore, the phosphotransfer step producing 3-phospho-MVAPP proceeds with inversion of configuration at P. Gentamicin nucleotidyl-transferase catalyzes the reaction of ATP with the C-2″ hydroxyl group of aminoglycoside antibiotics to produce AMP-2″-aminoglycosides, thereby inactivating the drugs. Enzymatic reaction of (S_p)-2′-deoxyadenosine 5′-O[α-17O] triphosphate with tobramycin produces (R_p)-[α-17O]dAMP-2″-tobramycin. Therefore, transfer of the 2′-deoxyadenosine 5′-phosphoryl group proceeds with inversion of configuration. Since both reactions are uncomplicated bisubstrate processes and both proceed with inversion at P, it is likely that both proceed by mechanisms involving direct, single-step phosphotransfer from the phospho-donor substrate to the acceptor, rather than by double-displacement mechanisms involving covalent, phosphoenzyme-intermediates.     

Utilizing Lifetimes to Suppress Random Coil Features in 2D IR Spectra of Peptides

We report that the waiting time delay in 2D IR pulse sequences can be used to suppress signals from structurally disordered regions of amyloid fibrils. At a waiting time delay of 1.0 ps, the random coil vibrational modes of amylin fibrils are no longer detectable, leaving only the sharp excitonic vibrational features of the fibril β-sheets. Isotope labeling with (13)C(18)O reveals that structurally disordered residues decay faster than residues protected from solvent. Since structural disorder is usually accompanied by hydration, we conclude that the shorter lifetimes of random-coil residues is due to solvent exposure. These results indicate that 2D IR pulse sequences can utilize the waiting time to better resolve solvent-protected regions of peptides and that local mode lifetimes should be included in simulations of 2D IR spectra.     

Perturbation approach to the complex-rotation method

Non-degenerate and almost degenerate perturbation theory is applied to the problem of calculating autoionizing resonances of the helium atom using the complex-rotation method. The radii of convergence of the series are often found to be too small to allow the perturbation method to have general utility.     

Weighted inequalities for real-analytic functions in ℝ<Superscript>2</Superscript>

Let ƒ and g be real-analytic functions near the origin in ℝ². Given 1 < p < ∞, we obtain a characterization of the set of positive numbers ∈ and δ that ensures

On global discontinuous solutions of Hamilton–Jacobi equationsSur des solutions globales discontinues des équations d'Hamilton–Jacobi

The uniqueness of classical semicontinuous viscosity solutions of the Cauchy problem for Hamilton–Jacobi equations is established for globally Lipschitz continuous and convex Hamiltonian H=H(Du), provided the discontinuous initial value function ?(x) is continuous outside a set Γ of measure zero and satisfies

(1)$\text{?(x)??}{}_7\text{(x):=}\text{lim}\text{inf}\text{y→x,}\text{y∈}\text{R}{}^{\mathrm{d}}\text{?Γ}\text{?(y).}$

We prove that the discontinuous solutions with almost everywhere continuous initial data satisfying ($\text{1}$) become Lipschitz continuous after finite time for locally strictly convex Hamiltonians. The L¹-accessibility of initial data and a comparison principle for discontinuous solutions are shown for a general Hamiltonian. The equivalence of semicontinuous viscosity solutions, bi-lateral solutions, L-solutions, minimax solutions, and L^∞-solutions is clarified. To cite this article: G.-Q. Chen, B. Su, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 113–118