Plexciton dynamics: exciton-plasmon coupling in a J-aggregate-Au nanoshell complex provides a mechanism for nonlinearity

Coherently coupled plasmons and excitons give rise to new optical excitations--plexcitons--due to the strong coupling of these two oscillator systems. Time-resolved studies of J-aggregate-Au nanoshell complexes when the nanoshell plasmon and J-aggregate exciton energies are degenerate probe the dynamical behavior of this coupled system. Transient absorption of the interacting plasmon-exciton system is observed, in dramatic contrast to the photoinduced transmission of the pristine J-aggregate. An additional, transient Fano-shaped modulation within the Fano dip is also observable. The behavior of the J-aggregate-Au nanoshell complex is described by a combined one-exciton and two-exciton state model coupled to the nanoshell plasmon.     

Plexcitonic nanoparticles: plasmon-exciton coupling in nanoshell-J-aggregate complexes

Stable Au nanoshell-J-aggregate complexes are formed that exhibit coherent coupling between the localized plasmons of a nanoshell and the excitons of molecular J-aggregates adsorbed on its surface. By tuning the nanoshell plasmon energies across the exciton line of the J-aggregate, plasmon-exciton coupling energies for these complexes are obtained. The strength of this interaction is dependent on the specific plasmon mode of the nanoparticle coupled to the J-aggregate exciton. From a model based on Gans theory, we obtain an expression for the plasmon-exciton hybridized states of the complex.     

Acceleration of the fermentation of kenkey, an indigenous fermented maize food of Ghana

Kenkey is a popular staple food of Ghana. It consists of fermented and cooked maize dough, wrapped in leaves. The traditional kenkey-making process is laborious and time consuming (4–6 days). An accelerated option for industrial manufacture of kenkey in sausage casings was developed, which takes approximately 24 h. Hydration of maize to 40% (w/w) moisture content was shortened from 48 to 10 h by pre-cracking the kernels. Fermentation was shortened from 3–4 days to 12 h by incorporating the aflata into the dumpling prior to fermentation, and by using a starter dough. Cooking time and thus energy expenditure was reduced from 2 h to 35 min by changing the dimensions of the kenkey mass from 10–15 cm diameter balls to 6 cm diameter cylinders. Due to the different conditions, yeasts were somewhat more active than in traditional kenkey, resulting in higher ethanol levels. However, these remained low and ethanol had disappeared after cooking. The combination of lactic acid fermentation and cooking resulted in a microbiologically stable product, even after the dumpling had been deliberately contaminated.     

Implementing the Orwell protocol over a fibre-based high-speed ATMnetwork

Asynchronous transfer mode (ATM) has emerged as a possible contender for the next generation switching system and fundamental transport basis for the broadband integrated services digital network (B-ISDN) and telecommunications in the future. It is widely thought of as the network to accommodate the uncertain requirements of future public communications because of its high degree of flexibility and service independency. The Orwell protocol developed by British Telecom can provide a communication base to meet the requirements of such a network. Orwell is used as a slotted ring protocol designed to carry a mixture of services which form the basis of an ATM network. The authors describe the realisation of a 155.52 Mbit/s fibre-optic physical layer from the Orwell protocol based on an ATM technology, and also discuss how the Orwell protocol can offer broadband transport capabilities and can provide access to and interwork with existing networks, such as telephone networks and 64 kbit/s based ISDNs