Fluorescence resonance energy transfer based MCM-EDTA-Tb3+-MES sensor

An in situ mesopourous surface imprinted polymeric (SIP) sensor was synthesized for a highly sensitive, selective, and kinetically faster detection of the high-vapor-pressure nerve gas surrogate methyl salicylate (MES). Visual detection occurred on the filtrate thin films at 25 pM. Other nerve gas surrogates, TP, DMP, DMMP, PMP, and 1,4-thioxane, were tested and showed a decrease in sensitivity compared to MES. In addition, 2,6-dipicolinic acid (DPA), a biological indicator, was also investigated and showed a decrease in sensitivity compared to MES. Finally, the detection plateau was reached at 40 s and at 1.5 x 10(-4) M from pH 6-11.     

Failure of a Freeze Dryer Slot Door

Freeze-drying is utilized in the biopharmaceutical industry to give higher stability, broader temperature tolerance, and longer shelf-life to formulations that are unstable in aqueous solution (Green and Perry, Perry’s Chemical Engineers’ Handbook, 1997). Freeze-drying equipment consists of a drying chamber, condensers, a cooling system, and a vacuum system. The drying chamber is where the product is placed to undergo the lyophilization process. The chamber has two access points: a maintenance door, located in a mechanical room, and a slot door, located in a sterile clean room. The maintenance door permits entry into the chamber. The slot door facilitates tray loading and unloading from the clean room using an automatic tray handling system. At 9:26 AM on March 2, 2008, a freeze-dryer failed during the steam-in-place (SIP) cycle. As a result of the failure, the slot door was plastically deformed. Several items in the proximity of the slot door sustained damage. Fortunately, no personnel were inside the clean room when the event occurred; there were no injuries or loss of life. The impact to production was severe. The event removed the freeze dryer from service for approximately 2 months, reducing bulk powder production capacity by 33% during the time it was down. The failure occurred because the slot door was not closed properly when the SIP cycle began. Instead of being completely restrained, it was allowed to become simply-supported, seriously compromising its pressure-containing ability.     

Distributed coordination space: Toward a theory of distributed team process and performance

This paper discusses a theoretical framework designed to elucidate the many issues surrounding distributed team performance, emphasizing how work characteristics associated with such teams may alter both the processes and the products emerging from distributed interaction. It is suggested that distributed team performance can best be understood through conceptualization of a coordination space within which distributed interaction occurs over time and distance. The goal is to take a socio-technical approach to distributed team research so that one can explicate both the cognitive consequences of a lack of co-location as well as the social consequences affecting interaction and team development when work is technology-mediated. The overall objective is to present a framework of 'distributed coordination' such that the principles most appropriate for distributed team performance can be developed.     

Encapsulation and delivery of protein from within poly(sulfobetaine) hydrogel beads

Advancement of therapeutic protein therapies can be hindered by their poor stability and short in vivo half-life. There is emerging evidence that biocompatible zwitterionic materials can prevent nonspecific interactions within proteins systems that contribute to protein instability. Here, zwitterionic hydrogel beads are synthesized from poly(sulfobetaine methyl methacrylate), pSB, using an inverse emulsion, free radical polymerization reaction technique. The transport properties within the zwitterionic hydrogels were characterized using ¹H NMR diffusometry. Equilibrium water content as high as 0.90 was measured for the synthesized hydrogels. Our study revealed that the pSB hydrogels are nontoxic, ion responsive, and their swelling is temperature dependent. The zwitterionic hydrogel beads were capable of undergoing lyophilization without aggregation. Hydrogel beads were loaded with a model protein, bovine serum albumin (BSA), using a postfabrication loading technique. The protein loading was studied using confocal laser microscopy, indicating homogenous protein dispersion of up to 40 μg BSA/mg hydrogel within the beads. Furthermore, the release rate of the protein from the synthesized hydrogel was studied at different crosslinker to monomer ratios. The protein encapsulated within the zwitterionic hydrogel had slower rates of thermal aggregation compared to nonencapsulated protein in solution. Furthermore, the protein-loaded inside the zwitterionic hydrogel better maintained its bioactivity.     

Adaptive Transmission for Direct-Sequence Spread-Spectrum Communications over Multipath Channels

A method is proposed and evaluated for energy-efficient adaptive transmission in direct-sequence spread-spectrum packet communications over specular multipath channels. The power, code rate, and symbol rate are adapted to match the multipath profile and propagation loss of the wireless communications channel. The adaptation of the transmission parameters is based on several statistics that can be derived in a spread-spectrum receiver. The transmission parameters are selected to optimize a performance measure that is related to the energy consumption and time duration of a packet transmission.     

Synthesis of Oxynitride Powders via Fluidized-Bed Ammonolysis, Part I: Large, Porous, Silica Particles

Reaction of silica (SiO₂) with triethanolamine (TEA, N(CH₂CH₂OH)₃) and ethylene glycol (EG) under conditions (∼200°C) where byproduct water is removed resulted in the formation of the neutral silatrane glycolate complex, N(CH₂CH₂O)₃SiOCH₂CH₂OH (or TEASiOCH₂CH₂OH) in essentially quantitative yield. Solutions of this neutral precursor in EG, when rapidly pyrolyzed and then oxidized at 500°C, formed porous ceramic powders with high specific surface areas (>500 m²/g). These powders were nitrided via ammonolysis in a fluidized-bed reactor at temperatures of 700°-1000°C. The resulting nitrided powders were characterized by thermal and chemical analyses, diffuse reflectance infrared spectroscopy, gas sorption, and X-ray photoelectron spectroscopy. The apparent activation energy for the nitridation process was determined to be 54 kJ/mol. Following nitridation, the powders were amorphous and had nitrogen contents as high as 21 wt% with retained surface areas >300 m²/g at 1000°C. Under the nitridation conditions used, the extent of nitrogen incorporation correlated linearly with increases in material density. This linearity suggested that the change in density occurred primarily because of changes in coordination that occurred as trivalent nitrogen replaced divalent oxygen in the glass structure and nominally because of viscous flow. The linear density increase also suggested that pore trapping did not occur under these processing conditions. This work serves as a model for ongoing studies on the nitridation of high-surface-area ceramic powders produced by the rapid pyrolysis of mixed-metal TEA alkoxides.     

Inorganic Colloidal Solution-Based Approach to Nanocrystal Synthesis of (Bi,Sb)2Te3

There is an interest in higher-ZT thermoelectric materials for high-watt-density cooling of electronics. Reducing thermal conductivity through increased phonon scattering in nanomaterials has been shown to be effective and is being investigated by many groups. Solution-based synthesis is a method for making thermoelectric nanomaterials that can provide particle sizes <20?nm and can be scaled to production quantities of materials. We are exploring an approach that proceeds through formation of an ??ink?? that contains inorganic colloidal nanocrystals of thermoelectric materials. This approach has the advantage that, by adjustments within the basic synthesis process, the size, shape, and composition of the nanocrystals can be tightly controlled to study changes in the transport properties. Currently we are making materials from inks that contain Bi₂Te₃ nanocrystals with Sb₂Te₃ ligands, suspended in a solvent. Powders formed by curing the inks are made into solid pellets by hot pressing, and the pellets are used for characterization and transport property measurements. The best result from our thermoelectric property measurements is ZT?=?0.9 with power factor of 27???W/cm?K², which to our knowledge is the best value for solution-based synthesis.     

Human Liver Fatty Acid Binding Protein‐1 T94A Variant,Nonalcohol Fatty Liver Disease,and Hepatic Endocannabinoid System

Hepatic endocannabinoids (EC) and their major binding/“chaperone” protein (i.e., liver fatty acid binding protein‐1 [FABP1]) are associated with development of nonalcoholic fatty liver (NAFLD) in animal models and humans. Since expression of the highly prevalent human FABP1 T94A variant induces serum lipid accumulation, it is important to determine its impact on hepatic lipid accumulation and the EC system. This issue was addressed in livers from human subjects expressing only wild‐type (WT) FABP1 T94T (TT genotype) or T94A variant (TC or CC genotype). WT FABP1 males had lower total lipids (both neutral cholesteryl esters, triacylglycerols) and phospholipids than females. WT FABP1 males' lower lipids correlated with lower levels of the N‐acylethanolamide DHEA and 2‐monoacylglycerols (2‐MAG) (2‐OG, 2‐PG). T94A expression in males increased the hepatic total lipids (triacylglycerol, cholesteryl ester), which is consistent with their higher level of CB1‐potentiating 2‐OG and lower antagonistic EPEA. In contrast, in females, T94A expression did not alter the total lipids, neutral lipids, or phospholipids, which is attributable to the higher cannabinoid receptor‐1 (CB1) agonist arachidonoylethanolamide (AEA) and its CB1‐potentiator OEA being largely offset by reduced potentiating 2‐OG and increased antagonistic EPEA. Taken together, these findings indicate that T94A‐induced alterations in the hepatic EC system contribute at least in part to the hepatic accumulation of lipids associated with NAFLD, especially in males.     

Synthesis of macroporous silica from solid-stabilised emulsion templates

We have investigated the microstructures of the solid residue left behind after the evaporation of solid-stabilised emulsions. The correlation between the microstructure and the properties and preparation conditions of the emulsions will be thoroughly discussed. The type of microstructure is related to the conditions (oil type, oil content, particle type, particle concentration and emulsion type) of the initial emulsion. Solid residues left after evaporation of oil-in-water emulsions containing volatile oils (relative to water) show a “knobbly” microstructure. When oils with similar or lower vapour pressure to that of water were used, “sponge-like” structures were obtained. For emulsions containing volatile oils, the mean drop diameter is similar to the mean pore diameter, whereas when oils with low vapour pressure are used, the pores are much smaller. Finally, this paper will illustrate that stable toluene-in-water emulsions leave porous microstructures, whereas water-in-toluene emulsions and emulsions close to the phase inversion show sheet-like or “knobbly” structure.