A Gravity Investigation of the Fayette Structural Zone and Surrounding Area, Northeast Iowa

A gravity survey was conducted over approximately 2600 square kilometers of northeast Iowa. The survey was undertaken to provide detailed gravity coverage at approximately one mile intervals and to investigate the sources of gravity anomalies in the study area. An additional objective was to verify with gravity data the presence of the Fayette Structural Zone, previously identified on the basis of magnetic linears. Four hundred and twenty-seven gravity stations were occupied and data from these stations combined with extant data from the Geological Survey Bureau of the Iowa Department of Natural Resources to produce the gravity interpretation. A Bouger gravity anomaly map was prepared and profile analysis undertaken to examine the source-configuration of intrusive bodies located within the basement of the study area. The gravity data, when combined with available magnetic and drill hole information, indicate a predominantly felsic basement with several gabbro and ultramafic intrusive bodies. Modeling of the gravity data failed to confirm either faulting or a dike at the presumed location of the Fayette Structural zone

Lithologic and Structural Interpretation of Gravity Data, Northeastern Iowa

A gravity survey was conducted over approximately 4600 square km of northeast Iowa. It was undertaken to provide detailed gravity coverage at approximately 1.6 km intervals and to model the source of several significant gravity and magnetic anomalies. 1,460 gravity stations were occupied in the survey area. Bouguer gravity and residual gravity anomaly maps were prepared, the latter using band-pass filter and trend-surface analysis techniques. The residual maps reveal that the large oval Bouguer gravity anomaly centered beneath Decorah can be traced to the southern border of the survey. Profiles crossing this feature were prepared from the Bouguer map and a total intensity magnetic anomaly map. These profiles, combined with drill hole information, support the interpretation of a mafic (troctolite) intrusive extending over 90 km from the northwest corner of Winneshiek County to near the southern boundary of Fayette County. The western portion is dominated by a shallow elastic basin while the eastern portion appears to be dominantly felsic in nature. The gravity interpretation did not provide conclusive evidence for faulting near Decorah although faulting cannot be ruled out

Synthesis, structure–affinity relationships, and modeling of AMDA analogs at 5-HT2A and H1 receptors: Structural factors contributing to selectivity

Histamine H1 and serotonin 5-HT2A receptors present in the CNS have been implicated in various neuropsychiatric disorders. 9-Aminomethyl-9,10-dihydroanthracene (AMDA), a conformationally constrained diarylalkyl amine derivative, has affinity for both of these receptors. A structure-affinity relationship (SAFIR) study was carried out studying the effects of N-methylation, varying the linker chain length and constraint of the aromatic rings on the binding affinities of the compounds with the 5-HT2A and H1 receptors. Homology modeling of the 5-HT2A and H1 receptors suggests that AMDA and its analogs, the parent of which is a 5-HT2A antagonist, can bind in a fashion analogous to that of classical H1 antagonists whose ring systems are oriented towards the fifth and sixth transmembrane helices. The modeled orientation of the ligands are consistent with the reported site-directed mutagenesis data for 5-HT2A and H1 receptors and provide a potential explanation for the selectivity of ligands acting at both receptors

Combining incompatible processes for deracemization of Praziquantel derivative under flow conditions

An efficient deracemization method for conversion of the racemate to the desirable (R)-enantiomer of Praziquantel has been developed by coupling incompatible racemization and crystallization processes. By a library approach, a derivative that crystallizes as a conglomerate has been identified. Racemization occurs via reversible hydrogenation over a palladium on carbon (Pd/C) packed column at 130 °C, whereas deracemization is achieved by alternating crystal growth/dissolution steps with temperature cycling between 5–15 °C. These incompatible processes are combined by means of a flow system resulting in complete deracemization of the solid phase to the desired (R)-enantiomer (98 % ee). Such an unprecedented deracemization by a decoupled crystallization/racemization approach can readily be turned into a practical process and opens new opportunities for the development of essential enantiomerically pure building blocks that require harsh methods for racemization

Microtubules gate tau condensation to spatially regulate microtubule functions.

Tau is an abundant microtubule-associated protein in neurons. Tau aggregation into insoluble fibrils is a hallmark of Alzheimer's disease and other types of dementia1, yet the physiological state of tau molecules within cells remains unclear. Using single-molecule imaging, we directly observe that the microtubule lattice regulates reversible tau self-association, leading to localized, dynamic condensation of tau molecules on the microtubule surface. Tau condensates form selectively permissible barriers, spatially regulating the activity of microtubule-severing enzymes and the movement of molecular motors through their boundaries. We propose that reversible self-association of tau molecules, gated by the microtubule lattice, is an important mechanism of the biological functions of tau, and that oligomerization of tau is a common property shared between the physiological and disease-associated forms of the molecule