Chromogenic Photonic Crystal Sensors Enabled by Multistimuli‐Responsive Shape Memory Polymers

Here novel chromogenic photonic crystal sensors based on smart shape memory polymers (SMPs) comprising polyester/polyether‐based urethane acrylates blended with tripropylene glycol diacrylate are reported, which exhibit nontraditional all‐room‐temperature shape memory (SM) effects. Stepwise recovery of the collapsed macropores with 350 nm diameter created by a “cold” programming process leads to easily perceived color changes that can be correlated with the concentrations of swelling analytes in complex, multicomponent nonswelling mixtures. High sensitivity (as low as 10 ppm) and unprecedented measurement range (from 10 ppm to 30 vol%) for analyzing ethanol in octane and gasoline have been demonstrated by leveraging colorimetric sensing in both liquid and gas phases. Proof‐of‐concept tests for specifically detecting ethanol in consumer medical and healthcare products have also been demonstrated. These sensors are inexpensive, reusable, durable, and readily deployable with mobile platforms for quantitative analysis. Additionally, theoretical modeling of solvent diffusion in macroporous SMPs provides fundamental insights into the mechanisms of nanoscopic SM recovery, which is a topic that has received little examination. These novel sensors are of great technological importance in a wide spectrum of applications ranging from environmental monitoring and workplace hazard identification to threat detection and process/product control in chemical, petroleum, and pharmaceutical industries.     

Optimization of Digital Growth of Thick N-Polar InGaN by MOCVD

Smooth 200 nm thick N-polar InGaN films were grown by metal–organic chemical vapor deposition (MOCVD) on sapphire using a digital approach consisting of a constant In, Ga, and N precursor flow with pulsed injection of H2 into the N2 carrier gas. Using this growth scheme, the H2 injection time was altered and the effect on the morphology and indium incorporation in the films observed. The effect of periodic insertion of additional GaN inter-layers on the surface morphology of the InGaN layers was also studied.     

Site-directed and deletion mutational analysis of the receptor binding domain of the interleukin-6 receptor targeted fusion toxin DAB389-IL-6

We have used site-directed and in-frame deletion mutationalanalysis in order to explore the structural features of theIL–6 portion of the diphtheria toxin-related interleukin–6(IL–6) fusion toxin DAB₃₈₉-IL–6 that are essentialfor receptorbinding and subsequent inhibition of protein synthesisin target cells. Deletion of the first 14 amino acids of theIL–6 component of the fusion toxin did not alter eitherreceptor binding affinity or cytotoxk potency. In contrast,both receptor binding and cytotoxic activity were abolishedwhen the C–terminal 30 amino acids of the fusion toxinwere deleted. In addition, we explored the relative role ofthe disulfide bridges within the IL–6 portion of DAB₃₈₉-IL–6in the stabilization of structure required for receptor-binding.The analysis of mutants in which the substitution of eitherCys⁴⁴⁰, Cys⁴⁴⁶, Cys⁴⁶⁹ or Cys⁴⁷⁹ to Ser respectively, demonstratesthat only the disulfide bridge between Cys⁴⁶⁹ and Cys⁴⁷⁹ isrequired to maintain a functional receptor binding domain. Inaddition, the internal in-frame deletion of residues 435–451,which includes Cys⁴⁴⁰ and Cys⁴⁴⁶, was found to reduce, but notabolish receptor binding affinity. These results further demonstratethat the disulfide bridge between Cys⁴⁴⁰ and Cys⁴⁴⁶ is not essentialfor receptor-binding. However, the reduced cytotoxic potencyof DAB₃₈₉-IL6(435–451) suggests that the conformationand/or receptor binding sites associated with this region ofthe fusion toxin is/are important for maintaining the wild typereceptor binding affinity and cytotoxic potency.     

Performance characteristics of the anaerobic baffled reactor

An anaerobic sludge blanket process, termed the anaerobic baffled reactor (ABR), has been developed and shows promise for industrial wastewater treatment. It combines the advantages of high stability and reliability with a high void volume. The risk of clogging and sludge bed expansion with resulting high microbial losses is reduced and there is no need for special gas collection or biological solids separation systems. Organic loadings as high as 36 g COD l^?1day^?1 have been achieved with COD removal rates of more than 24 g COD l^?1 day^?1 and methane production rates exceeding 6 volumes per day per unit volume of reactor. The hypothesis, that the ABR may be adequately modeled as a fixed-film reactor, has been supported. Therefore, a unified approach, based on fundamentals of bacterial kinetics and mass transport, appears useful for modeling this and similar systems. Pilot plant studies are necessary to determine the scaling factors of the system as well as the overall efficiency and costs.     

The Influence of Tunnel Geometry and Ventilation on the Heat Release Rate of a Fire

It has occasionally been observed that fires in tunnels appear to be significantly more severe than fires in the open air. A literature review has been carried out, comparing heat release data from fires in tunnels with heat release data from similar fires in the open air. A Bayesian methodology has been used to investigate the geometrical factors that have the greatest influence on heat release rate. It is shown that the heat release rate of a fire in a tunnel is influenced primarily by the width of a tunnel; a fire will tend to have a higher heat release rate in a narrow tunnel rather than in a wide tunnel. The observed relationship between heat release rate and tunnel width is presented. Results from a study investigating the variation of heat release rate with ventilation velocity for fires in tunnels are also presented. A method for making realistic estimates of the heat release rates of fires in tunnels, based on these results, is presented.     

Inefficiencies in electricity pricing in England and Wales

The combination of competition and regulation established in the electricity industry of England and Wales stimulates production efficiency and thus helps the industry to achieve low costs. Nevertheless this system does have some disadvantages as regards the incentives it presents to generators and to suppliers. These deficiencies arise because Use of System Charges both for Distribution and for Transmission are determined in a way that inadequately reflects the structure and level of marginal costs. Furthermore, the way that profiling for consumers taking less than 100 kW will work is likely to inhibit tariff innovation.     

Optical quorum cycles for efficient communication

Many optical networks face heterogeneous communication requests requiring topologies to be efficient and fault tolerant. For efficiency and distributed control, it is common in distributed systems and algorithms to group nodes into intersecting sets referred to as quorum sets. We show efficiency and distributed control can also be accomplished in optical network routing by applying the same established quorum set theory. Cycle-based optical network routing, whether using SONET rings or p-cycles, provides the sufficient reliability in the network. Light-trails forming a cycle allow broadcasts within a cycle to be used for efficient multicasts. Cyclic quorum sets also have all pairs of nodes occurring in one or more quorums, so efficient, arbitrary unicast communication can occur between any two nodes. Efficient broadcasts to all network nodes are possible by a node broadcasting to all quorum cycles to which it belongs (\(O(\sqrt{N})\)). In this paper, we propose applying the distributed efficiency of the quorum sets to routing optical cycles based on light-trails. With this new method of topology construction, unicast and multicast communication requests do not need to be known or even modeled a priori. Additionally, in the presence of network link faults, greater than 99 % average coverage enables the continued operation of nearly all arbitrary unicast and multicast requests in the network. Finally, to further improve the fault coverage, an augmentation to the ECBRA cycle finding algorithm is proposed.     

Carbon‐Nanotube–PDMS Composite Coatings on Optical Fibers for All‐Optical Ultrasound Imaging

Polymer–carbon nanotube composite coatings have properties that are desirable for a wide range of applications. However, fabrication of these coatings onto submillimeter structures with the efficient use of nanotubes has been challenging. Polydimethylsiloxane (PDMS)–carbon nanotube composite coatings are of particular interest for optical ultrasound transmission, which shows promise for biomedical imaging and therapeutic applications. In this study, methods for fabricating composite coatings comprising PDMS and multiwalled carbon nanotubes (MWCNTs) with submicrometer thickness are developed and used to coat the distal ends of optical fibers. These methods include creating a MWCNT organogel using two solvents, dip coating of this organogel, and subsequent overcoating with PDMS. These coated fibers are used as all‐optical ultrasound transmitters that achieve high ultrasound pressures (up to 21.5 MPa peak‐to‐peak) and broad frequency bandwidths (up to 39.8 MHz). Their clinical potential is demonstrated with all‐optical pulse‐echo ultrasound imaging of an aorta. The fabrication methods in this paper allow for the creation of thin, uniform carbon nanotube composites on miniature or temperature‐sensitive surfaces, to enable a wide range of advanced sensing capabilities.