Chemical Communication and Protocell-Matrix Dynamics in Segregated Colloidosome Micro-Colonies

Despite an emerging catalogue of collective behaviours in communities of homogeneously distributed cell-like objects, microscale protocell colonies with spatially segregated populations have received minimal attention. Here, we use microfluidics to fabricate Janus-like calcium alginate hydrogel microspheres with spatially partitioned populations of enzyme-containing inorganic colloidosomes and investigate their potential as integrated platforms for domain-mediated chemical communication and programmable protocell-matrix dynamics. Diffusive chemical signalling within the segregated communities gives rise to increased initial enzyme kinetics compared with a homogeneous distribution of protocells. We employ competing enzyme-mediated hydrogel crosslinking and decrosslinking reactions in different domains of the partitioned colonies to undertake selective expulsion of a specific protocell population from the community. Our results offer new possibilities for the design and construction of spatially organized cytomimetic consortia capable of endogenous chemical processing and protocell-environment interactivity.     

NHC-Adducts of Cyclopentadienyl-Substituted Alanes

The mono- and bis-iodo-substituted NHC-stabilized alanes (NHC) ⋅ AlH₂I and (NHC) ⋅ AlHI₂ offer a convenient entry for further substitution reactions at aluminum. Reactions of (NHC) ⋅ AlH₂I 1 – 4 with one equivalent of NaCp afforded the adducts (NHC) ⋅ AlH₂Cp 9 – 12 (NHC=Me₂Im^Me ( 9 ), iPr₂Im^Me ( 10 ), iPr₂Im ( 11 ), Dipp₂Im ( 12 )). Alane adducts with two Cp substituents (NHC) ⋅ AlHCp₂ 13 – 16 (NHC=Me₂Im^Me ( 13 ), iPr₂Im^Me ( 14 ), iPr₂Im ( 15 ), Dipp₂Im ( 16 )) were prepared by the analogous reaction of (NHC) ⋅ AlHI₂ 5 – 8 using two equivalents of NaCp. The unusual dimeric adducts ((NHC) ⋅ AlH₂Cp ⋅ CpMgI)₂ 17 – 19 (NHC=Me₂Im^Me ( 17 ), iPr₂Im^Me ( 18 ), iPr₂Im ( 19 )) were obtained from the reaction of 1 – 3 with MgCp₂.     

Dynamics of milling processes with variable time delays

A milling-process model with a variable time delay associated with each cutting tooth is presented in this article. The source of this variable time delay is the feed rate. The effect of the feed motion on the entry cutting angle, the exit cutting angle, and the amplitude of feed mark is also discussed. Loss-of-contact effects are also considered. The system dynamics is described by a set of delay differential equations with periodic coefficients and variable time delays. A semi-discretization scheme is presented for analyzing the stability of periodic orbits of this system. The analysis provides evidence of period-doubling bifurcations and secondary Hopf bifurcations. Good agreement is found between the numerical results obtained from this work and the results of related experimental studies.     

Study of multi-nucleon transfer reactions in 58, 64Ni + 207Pb collisions at the velocity filter SHIP

The European Physical Journal A - We investigated multi-nucleon transfer reactions in collisions of 58Ni + 207Pb and 64Ni + 207Pb at Coulomb barrier energies. The new aspect is that we used a...     

A spectral element approach for the stability analysis of time-periodic delay equations with multiple delays

This paper describes a general spectral element approach to study the stability of multiple time delay systems (MTDS). We show, for the first time, how this approach can be applied to periodic MTDS where the delays and the period are incommensurate. In contrast to prior works on MTDS, the spectral element approach is applicable to both autonomous as well as non-autonomous MTDS. Both MTDS of first order or higher can be obtained and systems with or without damping can be investigated. Since the spectral element approach uses efficient interpolation and a set of well-distributed interpolation points, the size of the matrices necessary for convergence is kept small. Further, since the spectral element approach is a semi-analytical procedure, it avoids the need to use tedious time marching algorithms to explore the stability behavior of the system.