Mechanistic studies of the photocatalytic oxidation of microcystin-LR: an investigation of byproducts of the decomposition process

Microcystins (cyclic heptapeptides) are produced by a number of freshwater cyanobacteria and cause concern in potable water supplies due to their acute and chronic toxicity. The present study reports the structural characterization of the degradation products of the photocatalytic oxidation of microcystin-LR, so aiding the mechanistic understanding of this process. TiO2 photocatalysis is a promising technology for removal of these toxins from drinking water. However, before it can be adopted in any practical application it is necessary to have a sufficient knowledge of degradation byproducts and their potential toxicity. Liquid chromatography-mass spectrometry analysis demonstrated that the major destruction pathway of microcystin appears to be initiated via three mechanisms: UV irradiation, hydroxyl radical attack, and oxidation. UV irradiation caused geometrical isomerization of microcystin converting the (4E), (6E) of the Adda configuration to (4E), 6(Z) or 4(Z), 6(E). Hydroxyl radical attack on the conjugated diene structure of Adda moiety produced dihyroxylated products. Further oxidation cleaved the hydroxylated 4-5 and/or 6-7 bond of Adda to form aldehyde or ketone peptide residues, which then were oxidized into the corresponding carboxylic acids. Photocatalysis also hydrolyzed the peptide bond on the ring structure of microcystin to form linear structures although this appeared to be a minor pathway.     

The role of college students' use of protective behavioral strategies in the relation between binge drinking and alcohol-related problems.

Previous research has examined protective behavioral strategies (PBS), or cognitive-behavioral strategies that may be employed when using alcohol to reduce consumption and related problems, as an important predictor of alcohol use and alcohol-related problems. More recently, studies have explored the mediating and moderating role of PBS on the relationships between key alcohol-related risk factors (i.e., drinking motives, depressive symptoms, binge drinking) and alcohol problems; however, current research examining PBS as a moderator of the relationship between alcohol use and related problems has methodological limitations. The purpose of the present study was to extend previous literature to examine the moderating effect of PBS on the relationship between binge drinking and alcohol-related problems. Data were collected and analyzed from 4,154 students at 13 midwestern universities. Findings indicated that PBS moderated the binge drinking-alcohol problems relationship for each of the four measures of binge drinking. However, effects were strongest when binge drinking was measured dichotomously versus continuously. Implications and future directions are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Uncertainty in macroeconomic policy-making: art or science?

Uncertainty is pervasive in economic policy-making. Modern economies share similarities with other complex systems in their unpredictability. But economic systems also differ from those in the natural sciences because outcomes are affected by the state of beliefs of the systems' participants. The dynamics of beliefs and how they interact with economic outcomes can be rich and unpredictable. This paper relates these ideas to the recent crisis, which has reminded us that we need a financial system that is resilient in the face of the unpredictable and extreme. It also highlights how such uncertainty puts a premium on sound communication strategies by policy-makers. This creates challenges in informing others about the uncertainties in the economy, and how policy is set in the face of those uncertainties. We show how the Bank of England tries to deal with some of these challenges in its communications about monetary policy.     

Bioreduction of uranium: environmental implications of a pentavalent intermediate

The release of uranium and other transuranics into the environment, and their subsequent mobility, are subjects of intense public concern. Uranium dominates the inventory of most medium- and low-level radioactive waste sites and under oxic conditions is highly mobile as U(VI), the soluble uranyl dioxocation (UO2)2+. Specialist anaerobic bacteria are, however, able to reduce U(VI)to insoluble U(IV), offering a strategy for the bioremediation of uranium-contaminated groundwater and a potential mechanism for the biodeposition of uranium ores. Despite the environmental importance of U(VI) bioreduction, there is little information on the mechanism of this transformation. In the course of this study we used X-ray absorption spectroscopy (XAS) to show that the subsurface metal-reducing bacterium Geobacter sulfurreducens reduces U(VI) by a one-electron reduction, forming an unstable (UO2)+ species. The final, insoluble U(IV) product could be formed either through further reduction of U(V) or through its disproportionation. When G. sulfurreducens was challenged with the chemically analogous (NpO2)+, which is stable with respect to disproportionation, it was not reduced, suggesting that it is disproportionation of U(V) which leads to the U(IV) product. This surprising discrimination between U and Np illustrates the need for mechanistic understanding and care in devising in situ bioremediation strategies for complex wastes containing other redox-active actinides, including plutonium.     

IPv6 Multicast Forwarding in RPL-Based Wireless Sensor Networks

In wireless sensor deployments, network layer multicast can be used to improve the bandwidth and energy efficiency for a variety of applications, such as service discovery or network management. However, despite efforts to adopt IPv6 in networks of constrained devices, multicast has been somewhat overlooked. The Multicast Forwarding Using Trickle (Trickle Multicast) internet draft is one of the most noteworthy efforts. The specification of the IPv6 routing protocol for low power and lossy networks (RPL) also attempts to address the area but leaves many questions unanswered. In this paper we highlight our concerns about both these approaches. Subsequently, we present our alternative mechanism, called stateless multicast RPL forwarding algorithm (SMRF), which addresses the aforementioned drawbacks. Having extended the TCP/IP engine of the Contiki embedded operating system to support both trickle multicast (TM) and SMRF, we present an in-depth comparison, backed by simulated evaluation as well as by experiments conducted on a multi-hop hardware testbed. Results demonstrate that SMRF achieves significant delay and energy efficiency improvements at the cost of a small increase in packet loss. The outcome of our hardware experiments show that simulation results were realistic. Lastly, we evaluate both algorithms in terms of code size and memory requirements, highlighting SMRF’s low implementation complexity. Both implementations have been made available to the community for adoption.     

From chamber to transformer: epistemological challenges in the methodology of theorised architectural history

While many architectural historians are conscious of their methodological procedures, this aspect of architectural history is rarely singled out for any prolonged consideration. In addition, while many architectural historians have, in recent years, made increasing reference to various forms of theory in order to inform their interpretations, this aspect of their work has been similarly devoid of any concentrated analysis. In order partly to redress this situation, this article does not offer any worked examples of historical analysis but, rather, focuses on the epistemological challenges facing the architectural historian. In particular, the article argues for the necessity of engaging with different kinds of critical theory in order to understand architecture. As a result, nine challenges can be identified for the discipline of architectural history: to theory as the object of study, to new architectures, to the framing of interpretative questions, to the critical nature of history, to interdisciplinary debates, to the opening of methodological procedures, to selfcritical development of the discipline, to re-engagement with critical theory, and to praxis. Only when these challenges are met, the authors contend, will a proper methodology of architectural history be constructed.     

Identification of Candidate Biomarker and Drug Targets for Improving Endometrial Cancer Racial Disparities

Racial disparities in incidence and survival exist for many human cancers. Racial disparities are undoubtedly multifactorial and due in part to differences in socioeconomic factors, access to care, and comorbidities. Within the U.S., fundamental causes of health inequalities, including socio-economic factors, insurance status, access to healthcare and screening and treatment biases, are issues that contribute to cancer disparities. Yet even these epidemiologic differences do not fully account for survival disparities, as for nearly every stage, grade and histologic subtype, survival among Black women is significantly lower than their White counterparts. To address this, we sought to investigate the proteomic profiling molecular features of endometrial cancer in order to detect modifiable and targetable elements of endometrial cancer in different racial groups, which could be essential for treatment planning. The majority of proteins identified to be significantly altered among the racial groups and that can be regulated by existing drugs or investigational agents are enzymes that regulate metabolism and protein synthesis. These drugs have the potential to improve the worse outcomes of endometrial cancer patients based on race.     

A potential method for simultaneous,semiochemical-based monitoring of Cryptolestes ferrugineus and Tribolium castaneum (Coleoptera: Cucujidae and Tenebrionidae)

Capture and analysis by gas-liquid chromatography of volatiles from adult Cryptolestes ferrugineus (Stephens) infesting rolled oats disclosed that the naturally-produced ratio of the aggregation pheromones 4,8-dimethyl-(E,E)-4,8-decadienolide (I) and (3Z, 11S)-dodecen-11-olide (II) is 1.6:1.0. Approximately 990 and 640 pg/male beetle/h of the 2 pheromones, respectively, were produced in a culture with 76 beetles of mixed age and sex/g of oats. A newly designed trap, which confines beetles responding to attractive odors within an enclosed chamber, was very effective in recapturing released C. ferrugineus when baited with a 13:16 mixture of I and (±)-II released at 1.25 μg/24h, and also in recapturing released adult Tribolium castaneum (Herbst), in response to the aggregation pheromone, 4,8-dimethyldecanal, released at 0.08 μg/24h. Moreover, the capture of each species to traps baited with both species' pheromones was no different than to traps baited with its pheromone alone. Thus the pheromones of both species can be used together in the same trap in semiochemical-based, pest monitoring systems.