High-temperature, microwave-assisted UV digestion: a promising sample preparation technique for trace element analysis

A novel, microwave-assisted, high-temperature UV digestion procedure was developed for the accelerated decomposition of interfering dissolved organic carbon (DOC) prior to trace element analysis of liquid samples such as, industrial/municipal wastewater, groundwater, and surface water, body fluids, infusions, beverages, and sewage. The technique is based on a closed, pressurized, microwave digestion device. UV irradiation is generated by immersed electrodeless Cd discharge lamps (228 nm) operated by the microwave field in the oven cavity. To enhance excitation efficiency an antenna was fixed on top of the microwave lamp. The established immersion system enables maximum reaction temperatures up to 250-280 degrees C, resulting in a tremendous increase of mineralization efficiency. Compared to open UV digestion devices, decomposition time is reduced by a factor of 5 and the maximum initial concentration of DOC can be raised by at least a factor of 50. The system's performance on a real-type sample was evaluated for the mineralization of skimmed milk (IRMM, CRM 151) and subsequent determination of trace elements using standard spectroscopic techniques. Recovery for Cd (109%), Cu (112%), Fe (99%), and Pb (96%) showed good agreement with the 95% confidence interval of the certified values.     

Photoreversible inhibition of cholinesterases: catalytic serine-labeled caged butyrylcholinesterase

The photoregulation of the catalytic activity of butyrylcholinesterase (BChE) was investigated by treating the enzyme with a newly developed carbamylating reagent, N-methyl-N-(2-nitrophenyl)carbamoyl chloride, which has proved to be an efficient photoremovable alcohol-protecting group. BChE was efficiently inhibited in a time- and concentration-dependent manner, and the enzyme could be protected against inhibition by active-site-specific ligands (that is, tacrine). The inactivation kinetics showed a biphasic character, which can be analyzed as the result of the existence of two conformational states in solution. Pseudo-irreversible inactivation of BChE, which results from catalytic serine carbamylation, was suggested by recovery of the enzyme activity after dilution and was demonstrated by X-ray crystallography. Remarkably, the 3D structure of the carbamylated BChE conjugate showed a nonambiguous carbamylation of the catalytic serine residue as the only chemical modification on the protein. The photoreversibility of the enzyme inactivation was analyzed by irradiating the inactivated enzyme at 365 nm and was shown to reach completion in some conditions. The efficient and specific "caging" of BChE, together with the availability of carbamylated BChE crystals, will offer a unique possibility to study the catalytic properties of this enzyme by kinetic crystallography after cryophotolytic uncaging of the enzyme conjugate crystals.     

Fear and Compassion: A Terror Management Analysis of Emotional Reactions to Physical Disability.

Objective: To examine whether death anxiety underlies emotional reactions toward people with disabilities (PWDs). Study Design: In Study 1, participants were primed with thoughts of death, read a vignette describing a PWD, and completed a compassion scale. Study 2 replicated the design of Study 1 and also examined the impact of target ethnicity. Studies 3 and 4 assessed the impact of physical disability on death-related cognitions and on fear of personal death. Results: Men reacted to death primes by emotionally withdrawing from a PWD and reporting less compassion, whereas women exhibited more compassionate responses. These differences in compassion were reflected in the death-related cognitions and fears sparked by physical disability. Conclusions: The human need to manage the terror of death shapes emotional reactions toward PWDs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling Replica Availability in Large Data Grids

Large Grid systems not only provide massive aggregated computing power but also an unprecedented amount of distributed storage space. Unfortunately, the dynamic behavior of the Grid, caused by varying resource availability, unpredictable data updates, and the impact of local site policies makes it difficult to exploit the full capabilities of Data Grids.We present an analytical model for determining the optimal number of replica servers, catalog servers, and catalog sizes to guarantee a given overall reliability in the face of unreliable components. Our model captures the characteristics of peer-to-peer-like environments as well as that of Grid systems. Empirical simulations confirm the accuracy of our analytical model.     

The rheology of collapsing zeolites amorphized by temperature and pressure

Low-density zeolites collapse to the rigid amorphous state at temperatures that are well below the melting points of crystals of the same composition but of conventional density. Here we show, by using a range of experimental techniques, how the phenomenon of amorphization is time dependent, and how the dynamics of order-disorder transitions in zeolites under temperature and pressure are equivalent. As a result, thermobaric regions of instability can be charted, which are indicative of polyamorphism. Moreover, the boundaries of these zones depend on the rate at which temperature or pressure is ramped. By directly comparing the rheology of collapse with structural relaxation in equivalent melts, we conclude that zeolites amorphize like very strong liquids and, if compression occurs slowly, this is likely to lead to the synthesis of perfect glasses.     

Managing complex augmented reality models.

Mobile augmented reality requires georeferenced data to present world-registered overlays. To cover a wide area and all artifacts and activities, a database containing this information must be created, stored, maintained, delivered, and finally used by the client application. We present a data model and a family of techniques to address these needs.     

Sports over a Distance

Sport is a domain full of movement-based interactions. These interactions typically have positive health effects as well as an impact on social bonding. We have investigated ways in which computer augmented devices can lead to new sport experiences and explored opportunities to combine physical activities with remote social bonding. Three prototypes have been implemented which showcase movement-based interaction in sports. “Breakout for Two” allows geographically distant users to play a physically exhausting ball game together. “FlyGuy” gives users a hang-glide experience controllable through body movement. “Push’N’Pull” uses isometric exercise equipment over a network to encourage users to complete a cooperative game whilst performing intense muscular actions. A comparison of these applications shows that such movement-based interaction in a networked environment allows players in different locations to achieve a work out and also to socialize. Based on these projects, we conclude with practical design implications for future Exertion Interfaces.