Design of 2-hydroxyethyl methacrylate-functional macromonomer dispersants by semi-batch cobalt chain transfer polymerization

Acrylic resins for automotive coatings are produced in nonaqueous dispersions (NAD) of nanometer size. These must be sterically stabilized by oligomeric dispersants, which are complex reactive oligomers possessing vinyl and hydroxyl functionalities, controlling the size of the nanocolloid. Hence, we have developed a kinetic Monte Carlo (kMC) model to improve the molecular structure of 2-hydroxyethyl methacrylate-functionalized poly (butyl methacrylate) (pBMA) dispersants of ca. 6,000 g/mol produced via semi-batch cobalt chain transfer polymerization (CCTP). The kMC-predicted degree of functionalization is benchmarked against a novel analytic expression suitable for oligomers. Stepwise adjustment of the semi-batch feed program illustrates the successive improvement in molecular structure of the dispersant product, finally arriving at a functionalization degree close to the theoretical maximum for CCTP.     

Study of the telomerization of dimethylaminoethyl methacrylate (DMAEMA) with mercaptoethanol. Application to the synthesis of a new macromonomer

The telomerization of dimethylaminoethyl methacrylate (DMAEMA) with mercaptoethanol initiated by 2,2′-azobisisobutyronitrile was first investigated at 70 °C and the influence of the type of solvent was studied. The results showed that well-defined telomers of DMAEMA could not be synthetized via telomerization of DMAEMA in water or water/acetonitrile mixture since the telomerization reaction is in competition with the nucleophilic addition of thiol onto the monomer. Transfer constants for mercaptoethanol in benzene and acetonitrile were determined by Mayo's and O'Brien's methods. The transfer constant obtained in acetonitrile (0,6) was higher than that obtained in benzene. This difference can be explained by the fact that the thiol was consumed by two reactions: nucleophilic addition and telomerization. The influence of solvents on the polymerization kinetics was enlightened. These results were applied to the synthesis of macromonomers of DMAEMA with isocyanatoethyl methacrylate (IEM). These macromonomers were copolymerized with styrene.     

Quantitative T 2 measurement of a single voxel with arbitrary shape using pinwheel excitation and CPMG acquisition

Objective The aim of this study is to present a new approach for making quantitative single-voxel T ₂ measurements from an arbitrarily shaped region of interest (ROI), where the advantage of the signal-to-noise ratio (SNR) per unit time of the single-voxel approach over conventional imaging approach can be achieved. Materials and methods Two-dimensional (2D) spatially selective radiofrequency (RF) pulses are proposed in this work for T ₂ measurements based on using interleaved spiral trajectories in excitation k-space (pinwheel excitation pulses), combined with a summed Carr–Purcell Meiboom–Gill (CPMG) echo acquisition. The technique is described and compared to standard multi-echo imaging methods, on a two-compartment water phantom and an excised brain tissue. Results The studies show good agreement between imaging and our method. The measured improvement factors of SNR per unit time of our single-voxel approach over imaging approach are close to the predicted values. Conclusion Measuring T ₂ relaxation times from a selected ROI of arbitrary shape using a single-voxel rather than an imaging approach can increase the SNR per unit time, which is critical for dynamic T ₂ or multi-component T ₂ measurements.     

Optimizing Reaction Conditions of the NanoOrange® Protein Quantitation Method for Use With Microplate-based Automation

Because of the rapidly expanding need for higher sample throughput in drug discovery, automation of corresponding biochemical analyses is desirable. In particular, automation of protein quantitation is crucial since its results are used extensively. Recently, a single-reagent fluorescent protein quantitation method (NanoOrange®) with attractive performance attributes has become available. While it can potentially be automated with liquid handling workstations, several of this method's reaction parameters need to be optimized.

We studied the time and a temperature dependence of the NanoOrange protein quantitation reaction in ninety-six well black microplates using either a temperature-regulated hot block or a microwave oven as heat sources. Fluorescence of the NanoOrange reaction was quantified with a multimode microplate spectral scanner.

Time-dependent heating profiles of filled microplates placed on hot blocks at fixed temperatures (45, 55, 65, 75, and 95°C) revealed temperature differences of 4–7°C cooler for the outside wells compared to the inner wells, however the maximum well temperature did not exceed 65°C. Similar time-temperature studies of microwave-heated microplates revealed an equilibrium temperature of 45–49°C that was 10–16°C lower than microplates that were block heated.

The bovine serum albumin (BSA): NanoOrange standard curves created using a hot block increased in slope from 45°C to 55°C, but then remained constant from 65 to 85°C.

Fluorescence of the BSA: NanoOrange standard curve created using a microwave oven was about half the magnitude of the hot block-derived curves, possible reflecting a lower energy transfer rate of the microwave oven. We conclude that the NanoOrange protein quantitation method can be automated if a microplatecompatible hot block with a 65-85°C surface can heat the microplate for minimum of 15 min prior to quantifying the reaction's fluorescence.     

Burnout and professional decision making: An analogue study.

Investigated the relationship between burnout and casework decision making among 70 child protection service workers using the Maslach Burnout Inventory and two simulated protection investigations in which information was acquired incrementally. For each case, Ss decided whether the stimulus child was at risk, whether the family was capable of change, and whether they would initiate legal proceedings on the child's behalf. Among those workers who decided there was no risk to the child in a case of chronic neglect, higher burnout scores predicted making this decision early and holding it with great and unwavering certainty. The findings extend the previous literature relating burnout to work avoidance by suggesting that burned-out personnel cope by denying the need for involvement in particularly demanding cases. Results are interpreted in terms of I. L. Janis and L. Mann's (1977) theory of defensive avoidance in stressful decision making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Net N immobilisation during the biodegradation of mucilage in soil as affected by repeated mineral and organic fertilisation

Repeated fertilisation of crops with manure commonly increases both the amount and the quality of soil organic matter, the mineralisation of which strongly determines the availability of N to plants. In the rhizosphere, the microbial mineralisation/immobilisation of N is enhanced due to rhizodeposition (release of organic compounds from roots). In this work, we studied N transformations during incubation of maize root mucilage in soils that had been previously fertilized with composted pig manure or with ammonium nitrate for 7 years. Our work revealed mucilage was rapidly mineralised (average half-life of 3 days), inducing a rapid N immobilisation of 94 mg N g⁻¹ of mucilage C, followed by a slow remineralisation. Fertilisation with manure induced a persistent stimulation of the soil organic matter mineralisation, leading to an enhanced content of soil inorganic N (+23% in 58 days of incubation). Due to this stimulation of microbial activity in the soil fertilized with manure, the decrease in inorganic N during the biodegradation of mucilage lasted a shorter time as compared to the mineral fertilisation. However, the type of fertilisation did not significantly change the amount of N immobilised.     

SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL PROPERTIES OF A FULLERENE TRIPHENYLPHOSPHONIUM SALT

A monofunctionalised fullerene triphenylphosphonium salt has been synthesised to investigate the potential for adaptation of fullerenes for biological application. The redox properties of fullerenes make them effective radical scavengers and consequently they are potential antioxidants in biological systems The triphenylphosphonium moiety was chosen because this lipophilic cation increases both the solubility and membrane permeability of attached compounds, and has been used as a delivery agent in biological systems in other contexts. Furthermore, the triphenylphosphonium moiety binds tightly to cognate antibodies, facilitating linkage of attached molecules to proteins. Here we report on the interaction of a triphenylphosphonium fullerene salt with biological systems and its binding of antibodies against the triphenylphosponium moiety.     

Modelling sweetness and texture perception in model emulsion systems

Model emulsion samples, prepared subject to a d-optimal response surface design, were used to investigate the effect of rapeseed oil, sugar and hydroxypropyl methyl cellulose thickener (HPMC) on perceived sweetness, textural attributes (thickness, stickiness, mouth-coating, dispersing), instrumental measures of apparent viscosity 50 s⁻¹ and Kokini oral shear stress. An increase in oil, sugar and HPMC resulted in an increase in perceived thickness, stickiness and mouth-coating, and a decrease in dispersion; sweetness was enhanced by the addition of both sugar and oil but suppressed by the addition of HPMC. Viscosity and Kokini oral shear stress were well correlated with oral thickness (r ² > 0.9). Validated multiple linear regression models highlighted several 2-factor interactions between ingredients. Model statistics indicated that the variation in data was well explained; the models were predictive and could be used to navigate the design space. Samples predicted to be iso-thick and iso-sweet could not be discriminated (P > 0.10) in a 3-alternative forced choice (3-AFC) test using 35 panellists.