13C NMR spectra of some 4-substituted protoadamantanes

The ¹³C NMR spectra of some mono- and geminal disubstituted protoadamantanes have been assigned with the aid of shift reagents.     

New approach to the synthesis of 6-ketosteroids via organoiron complexes.

New Methodology is described for the synthesis 6-ketosteroids, of potential value for the synthesis of β-ecdysone, $\text{via}$ tricarbonyl (4-methoxy-1-methylcyclohexadienyl) iron hexafluorophosphate $\text{1}$.     

Studien in Immunochemie. 21. Mitt.: Die Produkte des Abbaus von Blutgruppen-spezifischen Substanzen durch Ficin und Papain

Ohne Zusammenfassung     

The gallium-site donors germanium and silicon in gallium phosphide

The node in the Bloch part of the electron wave function expected for a Ga-site donor in GaP removes the usual valley-orbit splitting and associated chemical shift. However, the T₂ ground state can still show a small spin-valley splitting into Γ₈ and Γ₇ states, as previously verified for the Sn donor. We find that the optical properties of the Ge and Si donors deviate appreciably from this “normal” behaviour. The Ge donor is anomalously deep, E_D ～ 202 meV, yet binds an exciton by ～63 meV consistent with the Haynes rule for neutral donors in GaP. We find that this exciton possesses the large oscillator strength, f～3.5 × 10^-3, Zeeman and piezo-optical splittings characteristic of a Γ₆, 1s(A₁) ground state, like a P rather than Ga-site donor. However, f and the exciton localization energy are consistent with expectation for E_D ～ 200 meV, as measured from the lowest set of X conduction band minima, if we assume a symmetric A₁-like wave function. A possible explanation for this unexpected result is advanced. The much shallower Si donor, E_D～82 meV, binds an exciton by only ～ 14 meV, also consistent with the Haynes rule. By contrast, we find this Ga-site donor to be normal except that our Zeeman and piezo-optical results indicate an inverted spin-valley splitting, about 25% of that for the still shallower Sn donor. We also discuss the numerous low-lying excited states, some anomalous phonon replicas in the Ge and Si donor bound exciton spectra and the magneto-optical properties of a sharp line near 2.24 eV, attributed to the decay of excitons bound to (S)_p-(Ge)_p donor-acceptor associates.     

CO2-expanded liquid deposition of ligand-stabilized nanoparticles as uniform, wide-area nanoparticle films

Deposition of nanoparticles into uniform, wide-area thin films using CO(2) as an antisolvent is presented. Ligand-stabilized silver particles are controllably precipitated from organic solvents by pressurizing and expanding the solution with carbon dioxide. Subsequent addition of carbon dioxide as a dense supercritical fluid provides for removal of the organic solvent while avoiding the surface tensions common to evaporating solvents that are detrimental to nanoscale assemblies and structures. This brand new CO(2)-expanded liquid particle deposition technique allows for the targeted deposition of particles and results in more uniform and lower defect metal nanoparticle thin films than are provided by conventional solvent evaporation techniques.     

Technical considerations for the use of 15N-DNA stable-isotope probing for functional microbial activity in soils

Stable-isotope DNA probing is a culture-independent technique that may provide a link between function and phylogeny of active microorganisms. The technique has been used in association with 13C substrates while here we evaluate feasibility and limitations of 15N-DNA stable-isotope probing (SIP) using labelled and unlabelled pure microbial cultures or soil extracts. Our results showed that (15)N-DNA probing is feasible for cultures as well as soil samples. Limitations of 15N-DNA-SIP are (a) the need for relatively large quantities of DNA to visualise bands (although molecular resolution is much higher) and (b) 15N-DNA enrichment needed to ideally be >50 at%; however, this requirement can be lowered to approx. 40 atom% 15N with pure cultures using a modified CsCl centrifugation method (140K g for 69 h). These advances in 15N-DNA-SIP methodology open new opportunities to trace active microbial populations utilising specific N substrates in situ.     

Deoxyribozyme-based ligase logic gates and their initial circuits

A complete set (YES, NOT, AND, and ANDNOT) of molecular scale logic gates based on ligase deoxyribozymes was constructed. The activity of these gates was visualized through the formation of cascades with downstream phosphodieseterase YES gates, which performed fluorogenic cleavage.