Anion Sensing Porphyrin Functionalized Nanoparticles

Disulfide and dithiocarbamate functionalized porphyrins have been synthesized and used as protecting ligands for gold nanoparticle formation either via ligand substitution reactions or by direct synthesis. These nanoparticles have been shown to recognize anions via changes in the absorbance spectrum of the surface adsorbed porphyrin moieties. Association constants, derived from quantitative titrations, indicate a remarkable surface enhancement effect where the surface bound porphyrins bind anions much more strongly than the free receptor in solution.     

Effect of Ammonia on the Gas-Phase Hydration of the Common Atmospheric Ion HSO4?

Hydration directly affects the mobility, thermodynamic properties, lifetime and nucleation rates of atmospheric ions. In the present study, the role of ammonia on the formation of hydrogen bonded complexes of the common atmospheric hydrogensulfate (HSO₄⁻) ion with water has been investigated using the Density Functional Theory (DFT). Our findings rule out the stabilizing effect of ammonia on the formation of negatively charged cluster hydrates and show clearly that the conventional (classical) treatment of ionic clusters as presumably more stable compared to neutrals may not be applicable to pre-nucleation clusters. These considerations lead us to conclude that not only quantitative but also qualitative assessment of the relative thermodynamic stability of atmospheric clusters requires a quantum-chemical treatment.     

An Investigation of the Reduction and Reoxidation of Isolated Vanadate Sites Supported on MCM-48

The reduction and subsequent reoxidation of isolated vanadate species supported on silica was investigated using temperature-programmed reduction and oxidation, along with in-situ XANES and Raman spectroscopy. Approximately 70–80% of the vanadium was reduced to V³⁺ after reduction in H₂ at temperatures up to 923 K. Upon reduction, the vanadyl oxygen was removed and the three remaining V–O bonds are lengthened by 0.2 Å. The vanadate species are rapidly reoxidized when exposed to O₂, with the amount of oxygen uptake matching well with the amount removed during reduction. In-situ Raman spectroscopy during reoxidation in ¹⁸O₂ showed that significant scrambling occurs between gas phase oxygen and surface oxygen species during the reoxidation of the vanadate species.     

When laws and ethics collide: What should psychologists do?

At times the laws under which psychologists function may appear to contradict generally recognized ethical values and/or good clinical care. When these circumstances arise, psychologists must determine if a conflict really exists and, if so, seek solutions that reconcile respect for the law with their ethical values. At times, psychologists may decide to follow the law despite their ethical concerns. At other times, they may determine that a conscientious objection is warranted. The authors recommend options to consider when these situations arise and offer a decision-making process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and Characterisation of Some New Ferrocenyl- and Ferrocenylalkynyl-[60]Fullerene Compounds

We report the synthesis and characterisation of a series of ferrocenylfullerene compounds, and some new ferrocene derivatives required as intermediates. The new fullerene species are Fc-[60]fullerene, (8); Fc-C=C-[60]fullerene, (10); Fc-C=C-C=C-[60]fullerene, (12); and (η-C₅H₄SiBu₃)Fe(η-C₅H₄)-[60]fullerene, (14).     

Thermophysical Properties of W–Re Alloys Above the Melting Region

In earlier experiments we have studied pure elements with a fast pulse heating technique to obtain thermophysical properties of the liquid state. We report here results for thermophysical properties such as specific heat and dependences among enthalpy, electrical resistivity, and temperature, for four W–Re alloys (3.95, 21.03, 23.84, and 30.82 at % of Re) in a wide temperature range covering solid and liquid states. Thermal conductivity is calculated using the Wiedemann–Franz law for the liquid alloy, as.well as data for thermal diffusivity for the beginning of the liquid phase. Additionally, data for the entire temperature range studied have been analyzed in comparison with those of the constituent elements, tungsten and rhenium, since both metals have been studied previously with the same experimental technique. Such information is of interest in the field of metallurgy since W–Re alloys of low Re content in the region of mutual component solubility in the solid state are widely used as thermocouple materials for the purposes of high-temperature thermometry.     

Rainbow smelt population responses to species invasions and change in environmental condition

Invasive species can cause major disruptions in native food webs, yet the impact of species introductions and whether they will become invasive appears to be context-dependent. Rainbow smelt and alewife co-exist as invasive species in the Laurentian Great Lakes and as native species on the Atlantic coast of North America, but in Lake Champlain rainbow smelt is the dominant native forage fish and alewife are invasive. Alewife became abundant by 2007, providing an opportunity to explore the dynamics of these two species in a system where only one is invasive. We used data from a 28-year forage fish survey to compare demographics of rainbow smelt populations in three basins of Lake Champlain with different volumes, nutrient levels, and predator abundances. Rainbow smelt catch-per-unit-effort (CPUE) remained constant in the large, deep Main Lake before and after alewife invaded, but decreased in the two smaller basins. Declines were primarily a result of increased age-0 and age-1 mortality. Predation by top piscivores, system productivity, and competition for resources alone could not explain the patterns in CPUE across the basins. The mechanisms that allow alewife and rainbow smelt to co-exist could be related to system volume and oxythermal habitat availability, and may explain why the two species do not negatively affect each other in the Great Lakes. Summer hypoxia in the smaller basins could force individuals into smaller habitat volumes with higher densities of competitors and cannibalistic adult rainbow smelt. Habitat availability may mediate the impact of invasive alewife on native rainbow smelt.     

Designing content distribution networks for optimal cost and performance

One strategy for alleviating excess latency (delay) in the Internet is the caching of web content at multiple locations. This reduces the number of hops necessary to reach the desired content. This strategy is used for web content such as html pages, images, streaming video, and Internet radio. The network of servers which store this content, and the collections of objects stored on each server, is called a content distribution network (CDN). In order to optimally design a CDN, given a network topology with available server storage capacity at various points in the network, one must decide which object collections to place on each server in order to achieve performance or cost objectives. The placements must be within the storage limits of the servers and must reflect the request patterns for each collection of objects to be cached. Researchers have suggested formulations for the CDN problem which address performance by minimizing latency (the average number of hops is a commonly accepted measure of latency) from client to content, or formulations that focus on minimizing cost of storage and/or bandwidth. In this research, we develop a model which allows for the simultaneous treatment of performance and cost, present examples to illustrate the application of the model and perform a detailed designed experiment to gain insights into cost/hops tradeoff for a variety of network parameters.     

Register allocation for write activity minimization on non-volatile main memory for embedded systems

Non-volatile memories are good candidates for DRAM replacement as main memory in embedded systems and they have many desirable characteristics. Nevertheless, the disadvantages of non-volatile memory co-exist with its advantages. First, the lifetime of some of the non-volatile memories is limited by the number of erase operations. Second, read and write operations have asymmetric speed or power consumption in non-volatile memory. This paper focuses on the embedded systems using non-volatile memory as main memory. We propose register allocation technique with re-computation to reduce the number of store instructions. When non-volatile memory is applied as the main memory, reducing store instructions will reduce write activities on non-volatile memory. To re-compute the spills effectively during register allocation, a novel potential spill selection strategy is proposed. During this process, live range splitting is utilized to split certain long live ranges such that they are more likely to be assigned into registers. In addition, techniques for re-computation overhead reduction is proposed on systems with multiple functional units. With the proposed approach, the lifetime of non-volatile memory is extended accordingly. The experimental results demonstrate that the proposed technique can efficiently reduce the number of store instructions on systems with non-volatile memory by 33% on average.     

Ensuring reliability in B2B services: Fault tolerant inter-organizational workflows

In the age of Business-to-Business (B2B) collaboration, ensuring reliability of workflows underlying inter-organizational business processes is of significant importance. There are, however, quite a few challenges towards achieving seamless operation. Such challenges arise from heterogeneity in infrastructure and coordination mechanism at participant organizations, as well as time and cost associated with recovery from failure. Our research presents foundations for a reliable scheme for recovery from failure of workflow processes spanning through multiple business entities. First, a system model is adapted from the mobile computing literature that serves to establish the requirements to be enforced by each participating organization. In our model, we adopt the Maximal Sequence Path (MSP) approach from Yoo et al. (Lecture Notes in Artificial Intelligence 2132:222–236, 2001), as a means of decomposing workflows into mobile agent-driven processes that communicate via web services at each organization. This decomposition ensures defining logical points within the dynamics of a workflow instance for locating accurate and consistent states of the system for recovery in case of a failure. Then, a set of algorithms for various business scenarios are developed and presented as practical solutions. These algorithms are shown to create checkpoints such that the system is always in a globally consistent state. As such, these algorithms constitute a set of standards that can be incorporated in business process management suites that support reliable inter-organizational collaboration.