New high-energy luminescence bands from Co2+ in ZnSe

Three sharp absorption features in the energy range 2.36–2.55 eV have been detected in the transmission spectrum of Co-diffused ZnSe, and a number of luminescence transitions originating from the lowest of these states at 2.361 eV have been observed. Photoluminescence excitation spectra prove that these are high energy excited states of the Co²⁺_Zn impurity, a conclusion confirmed by comparison of measured and predicted luminescence energies. This represents the first identification of luminescence branching from a higher excited state of a transition metal ion in any semiconductor. The sharp, weakly phonon-coupled transitions involve either intra-impurity excitation or transitions from the impurity to localised states split off from a minimum in the conduction band. The implications of these observations for the mechanism of host-impurity energy transfer and for the nature of the excited state wavefunctions are discussed.     

meso-[{Ru(phen)2}2(mu-HAT)]4+: a high-affinity DNA hairpin probe {HAT = 1,4,5,8,9,12-hexaazatriphenylene; phen = 1,10-phenanthroline}

1H NMR spectroscopy and fluorescent intercalator displacement (FID) assays have been used to investigate the DNA-binding abilities of two series of dinuclear polypyridyl ruthenium(II) complexes of the form [{Ru(L)2}2(mu-BL)]4+ {L = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), 1,10-phenanthroline (phen), or 4,7-dimethyl-1,10-phenanthroline (Me2phen); BL = 2,2'-bipyrimidine (bpm) or 1,4,5,8,9,12-hexaazatriphenylene (HAT)}. Preliminary FID surveys of these metal complexes against a variety of different oligonucleotides revealed that those complexes based upon the HAT bridging ligand induced greater fluorescence decreases in dye-bound DNA than did their bpm-bridged counterparts, suggesting a higher binding affinity by the HAT-bridged species. Furthermore, the greatest fluorescence decreases were typically observed in an oligonucleotide featuring a six-base hairpin loop. The apparent binding affinity of the metal complexes was also found to be a function of the stereochemistry and identity of the terminal ligands of the complex. The meso (DeltaLambda) stereoisomer generally induced greater fluorescence decreases than did either enantiomer (DeltaDelta or LambdaLambda), phen-based terminal ligands performed better than bpy-based terminal ligands, and those terminal ligands with methyl substituents demonstrated stronger apparent binding than did their non-methylated analogues. NMR experiments on meso-[{Ru(phen)2}2(mu-HAT)]4+ and meso-[{Ru(Me2phen)2}2(mu-HAT)]4+ demonstrated that both complexes bound with high affinity to the six-base hairpin oligonucleotide at the stem-loop interface and provided evidence to support stronger binding by the methylated species. meso-[{Ru(phen)2}2(mu-HAT)]4+ was found to bind poorly to duplex DNA and smaller four-base hairpin loops in FID and NMR experiments, whereas FID data suggest that the methylated analogue binds relatively strongly to most oligonucleotide sequences (the four- and six-base hairpins in particular). These results demonstrate that binding affinity can come at the expense of selectivity, with meso-[{Ru(phen)2}2(mu-HAT)]4+ proving to be an efficient compromise between the two as a high-affinity DNA hairpin probe.     

Simultaneous attainment of high electron and ion temperatures in discharges with internal transport barriers in ASDEX upgrade

Internal transport barriers have been demonstrated to exist also under conditions with T(e) approximately T(i) approximately 10 keV and predominant electron heating of the tokamak core region. Central electron cyclotron heating was added to neutral beam injection-heated ASDEX Upgrade discharges with a preexisting internal transport barrier, established through programmed current ramping leading to shear reversal. Compared to a reference internal transport barrier discharge without electron cyclotron resonance heating, the electron heat conductivity in the barrier region was found not to increase, in spite of a fivefold increase in electron heat flux, and also angular momentum and ion energy transport did not deteriorate.     

Chemistry of the phenoxathiins V. Correlation of the crystal and molecular structure with pharmacologic activity associated with 7- and 8-chloro-l-azaphenoxathiin

The crystal and molecular structure of the 7- and 8-chloro analogs of the 1-azaphenoxathiin system are described. In contrast to previous compounds possessing antipsychotic type activity, the title compounds are both nearly planar, and demonstrate significant substituent location sensitivity, with the 7-chloro analog exhibiting significant biologic activity while the 8-chloro isomer is nearly devoid of activity. The relationship of these compounds to the isosterically related phenothiazines in terms of design and molecular geometry considerations is also described.     

Measuring Reform Practices in Science and Mathematics Classrooms: The Reformed Teaching Observation Protocol

The National Science Foundation has funded 22 Collaboratives for Excellence in Teacher Preparation. Despite the remarkable allocation of resources to this effort, it has proven exceptionally difficult to demonstrate the effectiveness of collaborative reform. In large part, this has resulted because of the difficulty of defining and measuring reform. The Reformed Teaching Observation Protocol (RTOP) was designed by the Evaluation Facilitation Group of the Arizona Collaborative for Excellence in the Preparation of Teachers (ACEPT). It is a 25‐item classroom observation protocol that is (a) standards based, (b) inquiry oriented, and (c) student centered. This instrument has provided the definition for reform and the basis for evaluation of the ACEPT collaborative. The data upon which this report is based were collected over a period of more than 2 years from 153 public school, college, and university mathematics and science classrooms. A trained team of observers consisting of two faculty members and seven graduate students was able to achieve exceptionally high levels of interrater reliability. Internal consistency, as estimated by Cronbach's alpha, was also remarkably high. Correlation coefficients ranging from 0.88 to 0.97 between RTOP scores for classrooms, and mean normalized gain scores for students in those classrooms on achievement measures demonstrate that reform, as defined by ACEPT and measured by the RTOP, has been effective.     

Bioanalysis of dried saliva spot (DSS) samples using detergent-assisted sample extraction with UHPLC-MS/MS detection

Dried saliva spot (DSS) sampling is a non-invasive sample collection technique for bioanalysis that can be potentially implemented at the patient's home. A UHPLC-MS/MS assay was developed using detergent-assisted sample extraction to quantify BMS-927711, a drug candidate in development for the treatment of migraines, in human DSS. By implementing DSS sampling at the patients' home, the bioanalytical sample collection for pharmacokinetic evaluation can be done at the time of the acute migraine attack without the need for clinical visits. DSS samples were prepared by spotting 15 μL of liquid saliva onto regular Whatman FTA™ DMPK-C cards and verified with a UV lamp (at λ 254 nm or 365 nm) during DSS punching. The 4-mm DSS punches in a 96-well plate were sonicated with 200 μL of [¹³C₂, D₄]-BMS-927711 internal standard (IS) solution in 20/80 MeOH/water for 10 min, followed by sonication with 50 μL of 100 mM NH₄OAc with 1.0% Triton-X-100 (as detergent) prior to liquid-liquid extraction with 600 μL EtOAc/Hexane (90:10). UHPLC-MS/MS was performed with an Aquity^® UPLC BEH C18 Column (2.1 × 50 mm, 1.7 μm) on a Triple Quad™ 5500 mass spectrometer. The assay was linear with a concentration range from 2.00 to 1000 ng mL⁻¹ for BMS-927711 in human saliva. The intra- and inter-assay precision was within 8.8% CV, and the accuracy was within ±6.7% Dev of the nominal concentration values. This UHPLC–MS/MS assay has been successfully applied to determine the drug's pharmacokinetics within a clinical study. For the first time, we observed BMS-927711 exposure in human DSS, confirming the suitability of this sampling technique for migraine patients to use at home. Detergent-assisted extraction with Triton-X-100 could be very useful in DSS or other dried matrix spot (DMS) assays to overcome low or inconsistent analyte recovery issues.     

Z4-Kerdock Codes, Orthogonal Spreads, and Extremal Euclidean Line-Sets

When m is odd, spreads in an orthogonal vector space of type⁺(2m + 2,2) are related to binary Kerdock codes and extremalline-sets in 2^{m + 1} with prescribed angles. Spreads in a 2m-dimensionalbinary symplectic vector space are related to Kerdock codesover Z₄ and extremal line-sets in with prescribed angles. These connections involve binary, realand complex geometry associated with extraspecial 2-groups.A geometric map from symplectic to orthogonal spreads is shownto induce the Gray map from a corresponding Z₄-Kerdock codeto its binary image. These geometric considerations lead tothe construction, for any odd composite m, of large numbersof Z₄-Kerdock codes. They also produce new Z₄-linear Kerdockand Preparata codes. 1991 Mathematics Subject Classification:primary 94B60; secondary 51M15, 20C99.