Factors affecting primary ionization in dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC/MS

The sensitivity of dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC/MS is generally reduced at higher solvent flow rates. Theory suggests that quenching of excited-state precursors to the dopant ions, via collisions with vaporized solvent molecules, may be one mechanism responsible for this trend. To ascertain if the primary rate of ionization is affected by quenching, experiments were performed utilizing an ionization detector to determine the primary ion current generated by irradiating vaporized mixtures of toluene dopant and methanol solvent. The results indicate that no loss of primary ion current occurs as the solvent flow is increased, provided the dopant-to-solvent ratio is held constant. Additional primary ion current can always be generated by increasing the dopant flow rate and/or the lamp power. Thus, quenching of excited-state precursors to the dopant ions, leading to a reduction in the primary rate of ionization, is not the mechanism responsible for the observed loss of sensitivity at higher liquid solvent flow rates.     

Thermally Stable 3,6‐Dinitropyrazolo[4,3‐c]pyrazole‐based Energetic Materials

3,6‐Dinitropyrazolo[4,3‐c]pyrazole was prepared using an efficient modified process. With selected cations, ten nitrogen‐rich energetic salts and three metal salts were synthesized in high yield based on the 3,6‐dinitropyrazolo[4,3‐c]pyrazolate anion. These compounds were fully characterized by IR and multinuclear NMR spectroscopies, as well as elemental analyses. The structures of the neutral compounds 4 and its salt 16 were confirmed by single‐crystal X‐ray diffraction showing extensive hydrogen‐bonding interactions. The neutral pyrazole precursor and its salts are remarkably thermally stable. Based on the calculated heats of formation and measured densities, detonation pressures (22.5–35.4 GPa) and velocities (7948–9005 m s^?1) were determined, and they compare favorably with those of TNT and RDX. Their impact and friction sensitivities range from 12 to >40 J and 80 to 360 N, respectively. These properties make them competitive as insensitive and thermally stable high‐energy density materials.     

Preparation of Cyan Dyes from 6-Diethylaminobenzo[b]furan-2-carboxaldehyde

6-Diethylaminobenzo[b]furan-2-carboxaldehyde was synthesized in four steps and 48% overall yield starting from 4-diethylaminosalicylaldehyde. Five cyan dyes were made from this aldehyde using malononitrile dimer and 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran. The crystal structures of two dyes are included.     

Enantioselective synthesis of (2R,3R)- and (2S,3S)-2- [(3-chlorophenyl)-(2-methoxyphenoxy)methyl]morpholine

The enantioselective synthesis of the (R,R)- and (S,S)-enantiomers of 1 from commercially available 3-chlorocinnamic acid is reported. The Sharpless asymmetric epoxidation was used to establish the stereocenters in the synthesis of both enantiomers of 1.     

3-Azido-N-nitro-1H-1,2,4-triazol-5-amine-based energetic salts

Twelve energetic nitrogen‐rich salts based on 3‐azido‐N‐nitro‐1H‐1,2,4‐triazol‐5‐amine were prepared and fully characterized by ¹H, ¹³C NMR, and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. The crystal structures of the neutral compound 3‐azido‐N‐nitro‐1H‐1,2,4‐triazole‐5‐amine ( 1 ) and its triaminoguanidinium salt ( 13 ) were determined by single‐crystal X‐ray diffraction. The density of 1 and its twelve salts ranged from 1.57 to 1.79 g cm^?3, and the heat of formation was calculated with the Gaussian 03 suite of programs. Compounds 1 – 13 exhibit promising detonation performances (pressure: 25.3–39.3 GPa; velocity: 8159–9409 ms^?1; EXPLO 5.05). Impact sensitivities were also determined by hammer tests and resulted ranging from 2.5 J (very sensitive) to >40 J (insensitive).     

Development of two synthetic routes to CE-178,253, a CB1 antagonist for the treatment of obesity

CE-178,253 benzenesulfonate (1) is a CB₁ antagonist discovered by Pfizer medicinal chemists. Two syntheses of this compound are described. The first, based on the discovery synthesis, involves assembly of an aryl-substituted pyrazolotriazine core onto which the second aryl moiety is installed by a Suzuki coupling; this route has been scaled to provide up to 6 kg of API. A second, more convergent route is also described, which installs the pyrazolotriazine containing both aryl substituents by condensation of a bromoketone with a substituted thiosemicarbazide. This route has been demonstrated on laboratory scale and is viewed as the preferred bond-forming sequence.     

Crossing the Barriers Between Preservice and Inservice Mathematics Teacher Education: An Evaluation of the Grant School Professional Development Program

A 2‐year school‐based mathematics professional development program is described and evaluated after its first year of implementation. Included in this program as its first course was a unique methods course in elementary education involving both preservice students and inservice teachers who cooperatively studied and applied reform pedagogy. The program resulted from the collaborative efforts of two institutions of higher education, a neighboring school district, the principal and teachers of one school within that district, and the state office of education. Evaluation of the first year of the program consisted of assessing the beliefs and perceptions of both preservice students and inservice teachers, along with an assessment of the mathematical achievement of the children within the classes of those teachers. Pre‐ and post‐assessments of the preservice students and inservice teachers' beliefs regarding reform pedagogy were administered using the IMAP [Integrating Mathematics and Pedagogy] Web‐Based Beliefs Survey (2006). Likert scale surveys were used to assess perceptions regarding course climate and participant relationships from both teacher groups. The mathematical achievement of children was assessed in three ways: The Wide Range Achievement Test‐3 ( Stone, Jastak, & Wilkinson, 1995 ), the Utah state criterion‐referenced assessment, and performance assessments developed specifically for use at the school. Data obtained from all sources indicated positive effects upon teachers and children, thus providing substantial evidence in support of both the value of the methods course itself and the overall professional development program. An additional evaluation will be conducted following the second year of the program.     

Atmospheric pressure-electron capture dissociation of peptides using a modified PhotoSpray ion source

An improved in-source atmospheric pressure-electron capture dissociation (AP-ECD) method is described. Building upon the early example of Laprévote's group, photoelectrons generated within a commercial PhotoSpray atmospheric pressure photoionization source are used to induce ECD of multiply charged peptide ions originating from an upstream heated nebulizer device. To attain high sensitivity, the method makes use of a novel electropneumatic-heated nebulizer to assist in the creation and transmission of multiply charged ions from sample solutions. Here, we demonstrate that readily interpretable AP-ECD spectra of infused peptides can be acquired from 100 fmol sample consumed, on a chromatographic time scale, using a conventional quadrupole time-of-flight (Q-ToF) mass spectrometer otherwise incapable of ECD/ETD experiments. Though much work remains to be done to develop and characterize the method, the results indicate that AP-ECD has the potential to be a practical new tool for the mass spectrometric analysis of peptides and proteins.     

Spatial heterogeneity in the muscle functional MRI signal intensity time course: effect of exercise intensity

It has previously been observed that during isometric dorsiflexion exercise, the time course of T2-weighted signal intensity (SI) changes is spatially heterogeneous. The purpose of this study was to test the hypothesis that this spatial heterogeneity would increase at higher contraction intensities. Eight subjects performed 90-s isometric dorsiflexion contractions at 30% and 60% of maximum voluntary contraction (MVC) while T2-weighted (repetition time/echo time=4000/35 ms) images were acquired. SI was measured before, during and after the contractions in regions of interest (ROIs) in the extensor digitorum longus (EDL) muscle and the deep and superficial compartments of the tibialis anterior (D-TA and S-TA, respectively). For all ROIs at 30% MVC, SI changes were similar. The maximum postcontraction SI was greater than the SI during exercise. At 60% MVC, SI changes during contraction were greater in the S-TA than in the D-TA and EDL. For the EDL and D-TA, the maximum postcontraction SI was greater than those during exercise. For the S-TA, the maximum postcontraction change was greater than the changes at t=8, 20 and 56 s but not the end-exercise value. We conclude that spatial heterogeneity increases during more intense dorsiflexion contractions, possibly reflecting regional differences in perfusion or neural activation of the muscle.     

A micro method for the determination of protein and screening of added water in meat and meat products

Summary The automatic Dumas method is feasible for determining the protein and screening for added water in meats and meat products. It is rapid, convenient, and requires less laboratory space and cost for routine operation. Homogeniety of the meat sample is important. Samples identified as positive for added water should be confirmed and quantified by the official macro-Kjeldahl method.

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Zusammenfassung Die automatisierte Dumas-Methode eignet sich für die Proteinbestimmung in Fleisch und Fleischwaren zwecks Ermittlung von Wasserzusätzen. Das Verfahren ist rasch durchzuführen, beansprucht wenig Platz im Labor und verursacht im Routinebetrieb nur geringe Kosten. Die Fleischproben müssen homogen sein. Gegebenenfalls festgestellter Wasserzusatz soll mit der offiziellen Makro-Kjeldahlmethode verifiziert werden.

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This paper was persented at the Sixth Middle Atlantic Regional Meeting of the American Chemical Society, February 3–5, 1971, Baltimore, Md.