Stereoselective synthesis, efficient light emission, and high bipolar charge mobility of chiasmatic luminogens

Stereoregular tetraphenylethene derivatives (Z)-o-BCaPTPE and (Z)-o-BTPATPE featured with chiasmatic conformations and aggregation-enhanced emission characteristics are synthesized using a McMurry reaction. Both luminogens exhibit high hole and electron mobilities. Organic light-emitting diodes (OLEDs) using (Z)-o-BCaPTPE and (Z)-o-BTPATPE as both the light-emitting and electron-transporting layers show high efficiencies.     

Schooling and the ownership of knowledge

This article considers the relationship between 'school' and 'non-school knowledge' and the classroom power imbalances they represent. The author critiques ways in which this distinction has been treated by earlier authors, arguing that 'non-school' or 'owned' knowledge has been defined simply as a negative of 'school knowledge', and that this does not aid our thinking in this area. She suggests that a key aspect of 'owned knowledge' is that students should have access to the power it represents, but that power-knowledge relationships within and outside of schools make this difficult to achieve.     

Compacted Modified Propellant Blocks as Traveling Charge in the Hybrid Shot Scheme

The burning of compacted modified propellant charges applied as a traveling charge in the hybrid shot scheme was studied. The block charges were manufactured by pressing fine propellant grains coated by a thin film of polyvinyl butyral. A stick from several pressed pellets was insulated over its lateral surface by a thin layer of silicon paste, glued to the back of the projectile and inserted into the barrel of the 23‐mm smooth‐bore laboratory gun. The loose‐packed accelerator charge was placed in the breech. Combustion was initiated by an igniter plug placed between the traveling and breech charges. A set of piezo‐quartz gauges placed in the breech and along the barrel, as well as a frame‐target device were used for recording characteristics of the firings. It is shown that blocks of this type, applied as the traveling charge, provide a stable burning process resulting in high ballistic performance. The block traveling charge preserves its integrity in the course of its motion along the barrel, and burning envelopes its total mass when pressure in the breach passes the maximum value. The descending portion of the pressure diagram demonstrates appreciable transformation, with convex or secondary hump sections. The shape of spatial pressure profiles behind the moving projectile is also transformed, and the pressure at the projectile butt end may be higher than the pressure in the breech. Compared to the conventional charges at the same maximum pressures the muzzle velocity increment attains 340 m s⁻¹ (or 23 %) for a light 35‐g projectile and 200 m s⁻¹ (or 19 %) for a heavy 104‐g projectile.     

Uptake, elimination, and relative distribution of perchlorate in various tissues of channel catfish

This study was undertaken to determine the kinetics of uptake and elimination of perchlorate in channel catfish, Ictalurus punctatus. Perchlorate--an oxidizer used in solid fuel rockets, fireworks, and illuminating munitions--has been shown to effect thyroid function, causing hormone disruption and potential perturbations of metabolic activities. For the uptake study, catfish were exposed to 100 mg/L sodium perchlorate for 12 h to 5 d in the laboratory. Perchlorate in tissues was analyzed using ion chromatography. The highest perchlorate concentrations were found in the head and fillet, indicating that these tissues are the most important tissues to analyze when determining perchlorate uptake into large fish. To calculate uptake and elimination rate constants for fillet, gills, G-I tract, liver, and head, fish were exposed to 100 ppm sodium perchlorate for 5 days, and allowed to depurate in clean water for up to 20 days. The animals rapidly eliminated the perchlorate accumulated showing the highest elimination in fillet (Ke = 1.67 day(-1)) and lowest elimination in liver (Ke = 0.79 day(-1)).     

The Use of a Custom-Built Coulometric Karl Fischer Instrument for the Determination of Water Content in Chocolate

A Karl Fischer (KF) coulometric titration method was designed and optimized for the quantitative determination of water in chocolate. A number of essential KF experimental parameters were investigated and assessed, including a study of polar extraction solvents, extraction times, interfering side reactions, and a comparison of pyridine-free KF coulometric reagents. The optimized protocol was found to be applicable to a wide variety of chocolate samples. Typical coulometric titration times for the chocolate samples were between 1 and 5 min, translating to water contents from 0.18 to 0.38 %?w/w. With this contribution, the quantification of water in chocolate using KF titration methods is now a simple, safe, and reliable process, comparable in terms of precision and accuracy to any commercially available KF coulometric apparatus.     

Analysis of biostimulated microbial communities from two field experiments reveals temporal and spatial differences in proteome profiles

Stimulated by an acetate-amendment field experiment conducted in 2007, anaerobic microbial populations in the aquifer at the Rifle Integrated Field Research Challenge site in Colorado reduced mobile U(VI) to insoluble U(IV). During this experiment, planktonic biomass was sampled at various time points to quantitatively evaluate proteomes. In 2008, an acetate-amended field experiment was again conducted in a similar manner to the 2007 experiment. As there was no comprehensive metagenome sequence available for use in proteomics analysis, we systematically evaluated 12 different organism genome sequences to generate sets of aggregate genomes, or "pseudo-metagenomes", for supplying relative quantitative peptide and protein identifications. Proteomics results support previous observations of the dominance of Geobacteraceae during biostimulation using acetate as sole electron donor, and revealed a shift from an early stage of iron reduction to a late stage of iron reduction. Additionally, a shift from iron reduction to sulfate reduction was indicated by changes in the contribution of proteome information contributed by different organism genome sequences within the aggregate set. In addition, the comparison of proteome measurements made between the 2007 field experiment and 2008 field experiment revealed differences in proteome profiles. These differences may be the result of alterations in abundance and population structure within the planktonic biomass samples collected for analysis.     

Maintaining ADR integrity

Georgetown Law Center Prof. Carrie Menkel‐Meadow discusses participants' responsibility to the process—a necessity to maintain effectiveness.