Calorimetry and thermodynamic aspects of heterotrophic,mixotrophic, and phototrophic growth

A simple stoichiometric model is proposed linking the biomass yield to the enthalpy and Gibbs energy changes in chemo-heterotrophic, mixotrophic, and photo-autotrophic microbial growth. A comparison with calorimetric experiments on the algae Chlorella vulgaris and Chlorella sorokiniana confirmed the trends but revealed large calorimetric measurement inaccuracies. The calorimetric data on purely photo-autotrophic growth was, however, in fair agreement with calculations. The thermodynamic characteristics of photosynthetic growth, including an estimation of the Gibbs energy dissipation, are compared with similar data for chemotrophic microbes.     

Phase transfer of agglomerated nanoparticles: deagglomeration by adsorbing grafted molecules and colloidal stability in polymer solutions

We aimed to develop liposomes for loading both cisplatin and quantum dots (QDs) for both drug delivery and bioimaging. The resultant quantum-dot-liposomes (QDLs) with cisplatin were characterized using dynamic light scattering, transmission electron microscopy (TEM), encapsulation efficiencies, and fluorescence intensity. QDLs composed of CdSe or CdSe/ZnS QDs represented a size of about 100?nm. The QDLs were prepared at a high QD loading efficiency of nearly 100?%. Most QDs were located within the liposomal bilayers as evidenced by TEM. Slow and sustained cisplatin release from QDLs was achieved. The cellular uptake of QDLs demonstrated effective internalization and significant fluorescence in melanoma cells. The signal derived from QDLs could be observed by different wavelength settings. The cisplatin-containing QDLs revealed higher cytotoxic activity compared to an equal dose of free cisplatin. CdSe/ZnS QDLs were intravenously administered to mice, and the biodistribution was observed with an in vivo imaging system. Significant fluorescence signal and cisplatin accumulation were detected in the brain and skin, as verified by ex vivo imaging and drug distribution. Liposomal inclusion could reduce the reticuloendothelial system uptake of QDs and cisplatin. QDLs evaluated in this study represent a new potential method for theranostic purposes.     

Finiteness of $$\pi _1$$-sensitive Hofer–Zehnder capacity and equivariant loop space homology

We prove that if M is a closed, connected, oriented, rationally inessential manifold, then the Hofer–Zehnder capacity of the unit disk bundle of the cotangent bundle of M is finite.     

Sodium borohydride mediated reduction of N-Boc protected purines and applications in the synthesis of 7-alkyladenines and tetrahydro[1,4]diazepino-[1,2,3-gh]purines

Electron deficient purines can be reduced to 7,8-dihydropurines when treated with cheap and easy-to-handle sodium borohydride in methanol. The dihydropurine formed by reduction of tris-Boc-protected adenine is a useful intermediate in efficient syntheses of 7-alkyladenines and tetrahydro[1,4]diazepino[1,2,3-gh]purines.     

In situ X‐ray Diffraction Studies of Cation and Anion Inter­calation into Graphitic Carbons for Electrochemical Energy Storage Applications

Graphite is a redox‐amphoteric intercalation host and thus capable to incorporate various types of cations and anions between its planar graphene sheets to form so‐called donor‐type or acceptor‐type graphite intercalation compounds (GICs) by electrochemical intercalation at specific potentials. While the LiC_x/C_x donor‐type redox couple is the major active compound for state‐of‐the‐art negative electrodes in lithium‐ion batteries, acceptor‐type GICs were proposed for positive electrodes in the “dual‐ion” and “dual‐graphite” cell, another type of electrochemical energy storage system. In this contribution, we analyze the electrochemical intercalation of different anions, such as bis(trifluoromethanesulfonyl) imide or hexafluorophosphate, into graphitic carbons by means of in situ X‐ray diffraction (XRD). In general, the characterization of battery electrode materials by in situ XRD is an important technique to study structural and compositional changes upon insertion and de‐insertion processes during charge/discharge cycling. We discuss anion (X^–) and cation (M⁺) intercalation/de‐intercalation into graphites on a comparative basis with respect to the M_x⁺C_n^– and C_n⁺X_n^– stoichiometry, discharge capacity, the intercalant gallery height/gallery expansion and the M–M or X–X in‐plane distances.     

Bioactivity-Based Analysis of Sunscreens Using the Luminescent Bacteria Vibrio fischeri

JPC – Journal of Planar Chromatography – Modern TLC - Sunscreen products are meant to protect people from damaging UVA and UVB radiation. However, in some formulations the UV filters...     

Die Zürcher Vorlesung von Schur über Darstellungstheorie

Im Jahre 1936, unmittelbar nach seiner Entlassung als Professor in Berlin, wurde Issai Schur an die ETH in Zürich eingeladen, um eine Vorlesung über die Darstellungstheorie von Gruppen zu halten. Die (kurze) Vorlesung wurde damals vom jungen Eduard Stiefel ausgearbeitet und in vervielfältigter Form herausgegeben. Es handelt sich dabei historisch um den ersten Lehrbuch-Text überhaupt, der ganz der Darstellungstheorie gewidmet war. Im vorliegenden Beitrag werden die Hintergründe der Einladung von Schur an die ETH beleuchtet, es wird ein Überblick über den Inhalt des Textes gegeben und schliesslich wird die damalige Veröffentlichung in einen historischen Bezug gesetzt.Der vorliegende Text ist eine leichte Überarbeitung eines Vortrages im Rahmen der Kolloquiums History of Mathematics; Algebra, Geometry and Number Theory and their Interactions, 10./11. Januar 2003, ETH Zürich.     

Functionalized Proline‐Rich Peptides Bind the Bacterial Second Messenger c‐di‐GMP

c‐di‐GMP is an attractive target in the fight against bacterial infections since it is a near ubiquitous second messenger that regulates important cellular processes of pathogens, including biofilm formation and virulence. Screening of a combinatorial peptide library enabled the identification of the proline‐rich tetrapeptide Gup‐Gup‐Nap‐Arg, which binds c‐di‐GMP selectively over other nucleotides in water. Computational and CD spectroscopic studies provided a possible binding mode of the complex and enabled the design of a pentapeptide with even higher binding strength towards c‐di‐GMP. Biological studies showed that the tetrapeptide inhibits biofilm growth by the opportunistic pathogen P. aeruginosa.     

Tailoring the microstructure of particle-stabilized wet foams

Inorganic colloidal particles which are in situ hydrophobized upon adsorption of short-chain amphiphilic molecules can be used as foam stabilizers. In this study, we tailor the microstructure of particle-stabilized wet foams, namely, the foam air content, average bubble size, and bubble size distribution, by changing the composition of the initial colloidal suspension. Wet foams featuring average bubble sizes between 10 and 200 microm and air contents between 45% and 90% were obtained by adjusting the amphiphile and particle concentration, pH, ionic strength, and particle size in the initial suspension. The influence of these parameters on the bubble size was satisfactorily described in terms of a balance between the shear stress applied during mixing and the counteracting Laplace pressure of the air bubbles. This model, originally developed for oil droplets in emulsions, can therefore be used to deliberately tailor the microstructure of particle-stabilized wet foams.