Hyperbranched Polylysine: A Versatile,Biodegradable Transfection Agent for the Production of Recombinant Proteins by Transient Gene Expression and the Transfection of Primary Cells

The feasibility of a new transfection agent, HBPL, for the production of recombinant IgG antibody via TGE as well as for the transfection of primary cells is studied. Under the conditions investigated, transfection of CHO‐DG44 cells using HBPL results in IgG yields that are comparable to those obtained with PEI. In experiments with CHO‐K1 cells and MEFs the use of HPBL allows to achieve transfection efficiencies comparable to or better than those obtained with PEI or Fugene®. HBPL‐mediated transfection does not require complex pre‐formation, works well in serum‐containing media and is biodegradable, which may prevent cumulative cytotoxicity and facilitates downstream processing.

     

Amontonian frictional behaviour of nanostructured surfaces

With nanotextured surfaces and interfaces increasingly being encountered in technological and biomedical applications, there is a need for a better understanding of frictional properties involving such surfaces. Here we report friction measurements of several nanostructured surfaces using an Atomic Force Microscope (AFM). These nanostructured surfaces provide well defined model systems on which we have tested the applicability of Amontons' laws of friction. Our results show that Amontonian behaviour is observed with each of the surfaces studied. However, no correlation has been found between measured friction and various surface roughness parameters such as average surface roughness (R(a)) and root mean squared (rms) roughness. Instead, we propose that the friction coefficient may be decomposed into two contributions, i.e., μ = μ(0) + μ(g), with the intrinsic friction coefficient μ(0) accounting for the chemical nature of the surfaces and the geometric friction coefficient μ(g) for the presence of nanotextures. We have found a possible correlation between μ(g) and the average local slope of the surface nanotextures.     

Logarithmic Picard groups,chip firing,and the combinatorial rank

Mathematische Zeitschrift - Illusie has suggested that one should think of the classifying group of $$M_X^{gp}$$ -torsors on a logarithmically smooth curve X over a standard logarithmic point as a...     

Control of the Intermolecular Coupling of Dibromotetracene on Cu(110) by the Sequential Activation of CBr and CH Bonds

Dibromotetracene molecules are deposited on the Cu(110) surface at room temperature. The complex evolution of this system has been monitored at different temperatures (i.e., 298, 523, 673, and 723 K) by means of a variety of complementary techniques that range from STM and temperature‐programmed desorption (TPD) to high‐resolution X‐ray spectroscopy (XPS) and near‐edge X‐ray absorption fine structure spectroscopy (NEXAFS). State‐of‐the‐art density‐functional calculations were used to determine the chemical processes that take place on the surface. After deposition at room temperature, the organic molecules are transformed into organometallic monomers through debromination and carbon‐radical binding to copper adatoms. Organometallic dimers, trimers, or small oligomers, which present copper‐bridged molecules, are formed by increasing the temperature. Surprisingly, further heating to 673 K causes the formation of elongated chains along the Cu(110) close‐packed rows as a consequence of radical‐site migration to the thermodynamically more stable molecule heads. Finally, massive dehydrogenation occurs at the highest temperature followed by ring condensation to nanographenic patches. This study is a paradigmatic example of how intermolecular coupling can be modulated by the stepwise control of a simple parameter, such as temperature, through a sequence of domino reactions.     

An improved analog equation method for non-linear dynamic analysis of time-fractional beams with discontinuities

Meccanica - In this paper, an improved version of the analog equation method (AEM) is proposed, ideally suitable for non-linear dynamic analysis of time-fractional beams with discontinuities....