Deconvolution of composite metastable peaks: A new method for the determination of metastable transitions occurring in the first field free region

The masses of daughter ions resulting from metastable transitions in the first field free region of a “reversed geometry” mass spectrometer can be accurately determined through a mass analysed ion kinetic energy scan at the apparent mass at which these daughter ions travel through the magnetic sector. A combination of these mass analysed ion kinetic scans with scanning the magnetic flux allows the resolution of overlapping metastable diffuse peaks.     

Rational Tuning of Fluorobenzene Probes for Cysteine‐Selective Protein Modification

Fluorobenzene probes for protein profiling through selective cysteine labeling have been developed by rational reactivity tuning. Tuning was achieved by selecting an electron‐withdrawing para substituent in combination with variation of the number of fluorine substituents. Optimized probes chemoselectively arylated cysteine residues in proteins under aqueous conditions. Probes linked to azide, biotin, or a fluorophore were applicable to labeling of eGFP and albumin. Selective inhibition of cysteine proteases was also demonstrated with the probes. Additionally, probes were tuned for site‐selective labeling of cysteine residues and for activity‐based protein profiling in cell lysates.     

Velocity of weakly turbulent flames of finite thickness

The velocity increase of a weakly turbulent flame of finite thickness is investigated using analytical theory developed in previous papers. The obtained velocity increase depends on the flow parameters: on the turbulent intensity, on the turbulent spectrum and on the characteristic length scale. It also depends on the thermal and chemical properties of the burning matter: thermal expansion, the Markstein number and the temperature dependence of transport coefficients. It is shown that the influence of the finite flame thickness is especially strong close to the resonance point, when the wavelength of the turbulent harmonic is equal to the cut off wavelength of the Darrieus–Landau instability. The velocity increase is almost independent of the Prandtl number. On the contrary, the Markstein number is one of the most important parameters controlling the velocity increase. The relative role of the external turbulence and the Darrieus–Landau instability for the velocity increase is studied for different parameters of the flow and the burning matter. The velocity increase for turbulent flames in methane and propane fuel mixtures is calculated for different values of the equivalence ratio. The present theoretical results are compared with previous experiments on turbulent flames. In order to perform the comparison, the theoretical results of the present paper are extrapolated to the case of a strongly corrugated flame front using the ideas of self-similar flame dynamics. The obtained theoretical results are in a reasonable agreement with the experimental data, taking into account the uncertainties of both the theory and the experiments. It is shown that in many experiments on turbulent flames the Darrieus–Landau instability is more important for the flame velocity than the external turbulence.     

Highly Selective Lysine Acylation in Proteins Using a Lys-His Tag Sequence

Chemical modification of proteins has numerous applications, but it has been challenging to achieve the required high degree of selectivity on lysine amino groups. Recently, we described the highly selective acylation of proteins with an N-terminal Gly-His₆ segment. This tag promoted acylation of the N-terminal N^α-amine resulting in stable conjugates. Herein, we report the peptide sequences His_n-Lys-His_m, which we term Lys-His tags. In combination with simple acylating agents, they facilitate the acylation of the designated Lys N^ϵ-amine under mild conditions and with high selectivity over native Lys residues. We show that the Lys-His tags, which are 7 to 10 amino acids in length and still act as conventional His tags, can be inserted in proteins at the C-terminus or in loops, thus providing high flexibility regarding the site of modification. Finally, the selective and efficient acylation of the therapeutic antibody Rituximab, pure or mixed with other proteins, demonstrates the scope of the Lys-His tag acylation method.     

Free surface and flow problem for a viscous liquid

An exact closed system of equations is proposed for describing the shape of the free surface of a viscous steady-state liquid in the 2D case in terms of the surface itself. A method that lowers the dimensionality in the Navier-Stokes equation is demonstrated, and its application in problems of steady-state flow past solids is considered.     

New designs and structure activity relationships in antitumoral aziridinyl cyclophospha(thia)zenes

Abstract

The partial aziridinolysis of (NPCl₂)_3,4 and (NPCl₂)₂ NSOCl yields non-geminal and geminal chloro-aziridinyl derivatives. Compounds N₃P₃Az_6-nR_n (R[dbnd]amino, alkoxy, aryloxy, id.) show in vitro and in vivo cytostatic activity. Structure-activity relationships are proposed. Phase I clinical trials of (NPAz₂)₂ NSOAz (Az[dbnd]1-aziridinyl) are summarized.