Calculated tautomeric equilibria and X-ray structures of 2-substituted N-methoxy-9-methyl-9H-purin-6-amines

Density Functional Theory calculations of nine 2-substituted N-methoxy-9-methyl-9H-purin-6-amines in the amino and imino tautomeric forms, as well as the complexes of the same with dimethyl sulfoxide (DMSO), were performed using two functionals (BP86 and B3LYP) and two basis sets (SV(P) and def2-TZVP). Solid-state structures of two of the compounds were obtained from single-crystal X-ray diffraction techniques. It was found that the inclusion of both an explicit hydrogen-bonding partner (DMSO) as well as continuum solvation effects, and vibrational corrections to energy, were necessary for qualitative and reasonable quantitative agreement with observed tautomeric ratios. The solution-optimized geometries and X-ray structures were found to be in good agreement. NMR spectroscopy confirmed the dependence of the tautomeric ratios on hydrogen-bonding abilities, in addition to the dipole moment of the solvent in question. Natural Bond Orbital charges on the N-7 nitrogen, as well as the tautomeric ratios were used to explain the observed reactivities of the compounds toward N-7 alkylation.     

Identification, cloning and characterization of a novel 47 kDa murine PKA C subunit homologous to human and bovine Cβ2

Background  

Two main genes encoding the catalytic subunits Cα and Cβ of cyclic AMP dependent protein kinase (PKA) have been identified in all vertebrates examined. The murine, bovine and human Cβ genes encode several splice variants, including the splice variant Cβ2. In mouse Cβ2 has a relative molecular mass of 38 kDa and is only expressed in the brain. In human and bovine Cβ2 has a relative molecular mass of 47 kDa and is mainly expressed in lymphoid tissues.     

Inclusive Science Education: Classroom Teacher and Science Educator Experiences in CLASS Workshops

Inclusion is the meaningful participation of students with disabilities in general education classrooms. The CLASS project (Creating Laboratory Access for Science Students) is a unique initiative offering training and resources to help educators provide students with a variety of physical, sensory and learning disabilities equal access in the science laboratory or field. To determine whether participants believed a 2‐week residential workshop sponsored by CLASS raised disability awareness and provided teacher training in inclusive science teaching practice, a multipoint Likert scale survey and questionnaire was completed by all participants (N= 20) in four workshops. Participants reported large gains in their preparedness to teach science to students with disabilities. Participants also reported gains in their familiarity with instructional strategies, curricula, and resources and their ability to design, select, and modify activities for students with disabilities. Finally, shifts in attitudes about teaching science to students with disabilities were noted.     

Internal standard tracked dilution to overcome challenges in dried blood spots and robotic sample preparation for liquid chromatography/tandem mass spectrometry assays

Dried blood spot (DBS) technology is an emerging alternative for sample collection in bioanalysis. Dilution for DBS samples is a challenge due to its solid sample format. Currently, DBS samples requiring dilution were first extracted as regular samples and then diluted with extracted blank samples containing internal standard (IS). Since the dilution step is a volume-critical step, extra care has to be taken to achieve accurate dilution when dealing with limited volume extracted samples. Here, we introduce an alternative sample dilution for liquid chromatography/tandem mass spectrometry (LC/MS/MS) assays using IS to track the dilution step. Dilution factor-adjusted IS working solution was first added to the sample requiring dilution before sample processing; subsequently, the processed sample was approximately diluted into the assay linear response range before LC/MS/MS analysis. We define this approach as "IS-tracked dilution". The advantage of this approach is that the diluting step is tracked by the IS and is no longer a volume-critical step. Another recognized challenge related to sample dilution is automatic sample dilution using a liquid handler. This "IS-tracked dilution" may also help address some of the challenges for automatic sample dilution of liquid samples. This new dilution approach was proven to be effective and convenient in both plasma assays and DBS assays using omeprazole as a probe compound.     

Allene-alkyne cross-coupling for stereoselective synthesis of substituted 1,4-dienes and cross-conjugated trienes

Titanium-mediated cross-coupling of allenic alcohols with alkynes has been investigated. Divergent reaction pathways were discovered that provide either stereodefined 1,4-dienes or substituted cross-conjugated trienes. In short, allene substitution plays a critical role in the determination of reaction pathway.     

Allene-alkyne cross-coupling for stereoselective synthesis of substituted 1,4-dienes and cross-conjugated trienes

Titanium-mediated cross-coupling of allenic alcohols with alkynes has been investigated. Divergent reaction pathways were discovered that provide either stereodefined 1,4-dienes or substituted cross-conjugated trienes. In short, allene substitution plays a critical role in the determination of reaction pathway.     

Dynamical stability and pure thermodynamic phases

A notion of stability of dynamics under distant perturbations is introduced. It is demonstrated, for quasi-local systems, that the stability of an equilibrium state under the same perturbations implies the state is factorial, i.e. strongly clustering in space. We also characterize the set of perturbations necessary to ensure the equivalence of stability and factorialness.