Selected first row transition metal coordination compounds of 2-(N-Aminomethyl)-3-Quinuclidinone chelates

As part of a project directed towards elucidating the characteristics of ligands which coordinate to give complexes having tetrahedral structures, a study of chelates containing the bulky quinuclidine group has been made. With 2-(N-morpholinylmethyl)-3-quinuclidinone (MQN), complexes having the general formula M(MQN)X₂ were prepared where the metal ion was Co(II), Ni(II), Fe(II), Cu(II), and Mn(II). The ligands 2-(N-piperidinylmethyl)-3-quinuclidinone (PQN) and 2-(N-dimethylaminomethyl)-3-quinuclidinone (DQN) were prepared along with the analogous cobalt(II) chloride complexes. The series of complexes Co(MQN)X₂ where X = Cl, Br, or I were prepared, and magnetic susceptibilities and spectral data obtained. They have room temperature magnetic moments in the range 4.66-4.85 with slight decreases at lower temperatures. Spectral parameters derived from their electronic absorption spectra are typical of tetrahedrally coordinated Co(II) ions with Dq varying between 390-430 cm⁻¹ in the solid phase. Band assignments corresponding to spin-allowed d-d transitions were made. Properties of Co(MQN)Cl₂, Co(PQN)Cl₂, and Co(DQN)Cl₂ show distortion from tetrahedral symmetry in the order MQN \u3c PQN \u3c DQN in the solid phase and PQN \u3c MQN ~ DQN in solution. Infrared spectra are essentially identical for the MQN series and tentative Co-X stretching frequencies are given. The complex Co(MQN)(NCS)₂ · C₂H₅OH is octahedrally coordinated by virtue of bridging thiocyanate groups. A value of µeff of 4.38 was found for this compound and band assignments yield 970 cm⁻¹ for Dq in pure Oh symmetry. A series of nickel complexes, viz., Ni(MQN)X₂ where X = Cl, Br, or I were obtained by the addition of the appropriate metal salt to MQN. Two forms of a complex of general formula Ni(MqN)Cl₂ were prepared and characterized. The purple Ni(MQN)Cl₂ analog along with the corresponding purple bromide and green iodide were found to have pseudotetrahedral symmetries. Magnetic susceptibility data at 300º K give µeff values between 3.35 and 3.58 for these compounds. Further data were obtained from room temperature to 18º K for the three halide complexes and these show a slight decrease in µeff for Ni(MQN)Br₂, a slight increase in µeff for purple Ni(MQN)Cl₂, and a sharp increase in µeff for Ni(MQN)I₂ below 50º K. Some of the low temperature moments were found to be dependent upon the strength of the magnetic field. Band assignments were made and calculation of spectral parameters yield Dq values in the solid phase ranging from 525 to 550 cm⁻¹. The electronic absorption spectrum of Ni(MQN)Br₂ at 25º and 300º K is reported and tentative Ni-X stretching frequencies are given. In contrast to the purple, pseudotetrahedral Ni(MQN)Cl₂, an off-white compound of the same formula was prepared and characterized. This off-white analog contains octahedrally coordinated nickel atoms by virtue of halogen bridging. µeff is 3.40 at room temperature and Dq is found to be 1000 cm⁻¹. Low temperature electronic absorption spectra and infrared data the range 600-200 cm⁻¹ are given. Compounds having the formulas Ni(MQN)(NCS)₂ · CH₃OH and Ni(MQN)(NO₃)₂ were found to have octahedral symmetries about the central metal atom. The thiocyanate complex is believed to contain bridging and terminal thiocyanate groups and a structure similar to that of Co(MQN)(NCS)₂ · C₂H₅OH is proposed. The nitrate complex contains bridging or chelating nitrate groups. Room temperature µeff is 3.23 and Dq is 970 cm⁻¹ for Ni(MQN)(NCS)₂ · CH₃OH. These parameters are, respectively, 3.33 and 950 cm⁻¹ for Ni(MQN)(NO₃)₂. The only iron(II) complex obtained was Fe(MQN)Cl₂ and this has a pseudotetrahedral structure. The electronic absorption spectrum shows a broad, asymmetric band at about 6700 cm⁻¹ assigned to the ⁵E→⁵T₂ transition in pure Td symmetry. µeff is 5.27 at 294º and is essentially independent of temperature, as expected. The Mössbauer parameters ΔEQ and δ are 2.74 mm/sec and 0.91 mm/sec, respectively, at 300º K. Two manganese(II) complexes are reported, viz., Mn(MQN)Cl₂ and Mn(MQN)Br₂. Electronic absorption spectral bands could not be observed and values of µeff were not helpful in deducing the structures of these compounds. A comparison of d-spacings obtained for the Mn(II) complexes with the corresponding Ni(II) and Co(II) complexes was not useful. The series of complexes Cu(MQN)X₂ where X= Cl, Br, or NO₃ have been prepared and each was found to exhibit a broad band in the electronic absorption spectrum as is usually found in Cu(II) complexes. Values of µeff were found in the range 1.83-1.89 and showed essentially no dependence upon temperature. Comparison of X-ray diffraction data with analogous Co(II) and Ni(II) compounds and examination of Cu-X stretching frequencies suggested pseudotetrahedral structures for the chloride and bromide complexes. The nitrate complex is most likely octahedrally coordinated through bridging or chelating nitrate groups. Confirmation of these structures must await an X-ray crystallographic study. Perchlorate complexes of several metal(II) compounds were prepared. The cobalt, nickel, and copper complexes were found to contain two MQN ligands in the coordination spheres. Some of the complexes were hydrates. µeff was found to be 4.36 for Co(MQN)₂(ClO₄)₂; 4.02 for Ni(MQN)₂(ClO₄)₂ · 4H₂O; 1.98 for Cu(MQN)₂ (ClO₄)₂. All of the perchlorate complexes appeared to be tetrahedrally coordinated with two nitrogen-coordinated ligands. --Abstract, pages ii-v

Character Selection During Interactive Taxonomic Identification: “Best Characters”

Software interfaces for interactive multiple-entry taxonomic identification (polyclaves) sometimes provide a “best character” or “separation” coefficient, to guide the user to choose a character that could most effectively reduce the number of identification steps required. The coefficient could be particularly helpful when difficult or expensive tasks are needed for forensic identification, and in very large databases, uses that appear likely to increase in importance. Several current systems also provide tools to develop taxonomies or single-entry identification keys, with a variety of coefficients that are appropriate to that purpose. For the identification task, however, information theory neatly applies, and provides the most appropriate coefficient. To our knowledge, Delta-Intkey is the only currently available system that uses a coefficient related to information theory, and it is currently being reimplemented, which may allow for improvement. We describe two improvements to the algorithm used by Delta-Intkey. The first improves transparency as the number of remaining taxa decreases, by normalizing the range of the coefficient to [0,1]. The second concerns numeric ranges, which require consistent treatment of sub-intervals and their end-points. A stand-alone Bestchar program for categorical data is provided, in the Python and R languages. The source code is freely available and dedicated to the Public Domain

A comparison of concepts of the state in Roman Catholicism and the ecumenical movement.

Thesis (Ph.D.)--Boston UniversityThis study attempts a systematic survey and comparison of Roman Catholic and Ecumenical Movement (since 1925) doctrines of the state conceived as a universal institution and the political instrument of society. It deals with the theoretical doctrines of each group, and not with either the historical evolution of these concepts, or with the actual practices of these groups in their relations with particular states. Strictly speaking, it is not a comparison of Roman Catholic and Protestant views of the state because the Movement embraces some non-Protestants. [TRUNCATED

Intracranial pressure monitoring in normal dogs using subdural and intraparenchymal miniature strain-gauge transducers.

BackgroundMonitoring of intracranial pressure (ICP) is a critical component in the management of intracranial hypertension. Safety, efficacy, and optimal location of microsensor devices have not been defined in dogs.Hypothesis/objectiveAssessment of ICP using a microsensor transducer is feasible in anesthetized and conscious animals and is independent of transducer location. Intraparenchymal transducer placement is associated with more adverse effects.AnimalsSeven adult, bred-for-research dogs.MethodsIn a prospective investigational study, microsensor ICP transducers were inserted into subdural and intraparenchymal locations at defined rostral or caudal locations within the rostrotentorial compartment under general anesthesia. Mean arterial pressure and ICP were measured continuously during physiological maneuvers, and for 20 hours after anesthesia.ResultsBaseline mean ± SD values for ICP and cerebral perfusion pressure were 7.2 ± 2.3 and 78.9 ± 7.6 mm Hg, respectively. Catheter position did not have a significant effect on ICP measurements. There was significant variation from baseline ICP accompanying physiological maneuvers (P < .001) and with normal activities, especially with changes in head position (P < .001). Pathological sequelae were more evident after intraparenchymal versus subdural placement.Conclusions and clinical importanceUse of a microsensor ICP transducer was technically straightforward and provided ICP measurements within previously reported reference ranges. Results support the use of an accessible dorsal location and subdural positioning. Transient fluctuations in ICP are normal events in conscious dogs and large variations associated with head position should be accounted for when evaluating animals with intracranial hypertension

Impact of Simulated 1/f Noise for HI Intensity Mapping Experiments

Cosmology has entered an era where the experimental limitations are not due to instrumental sensitivity but instead due to inherent systematic uncertainties in the instrumentation and data analysis methods. The field of HI intensity mapping (IM) is still maturing, however early attempts are already systematics limited. One such systematic limitation is 1/f noise, which largely originates within the instrumentation and manifests as multiplicative gain fluctuations. To date there has been little discussion about the possible impact of 1/f noise on upcoming single-dish HI IM experiments such as BINGO, FAST or SKA. Presented in this work are Monte-Carlo end-to-end simulations of a 30 day HI IM survey using the SKA-MID array covering a bandwidth of 950 and 1410 MHz. These simulations extend 1/f noise models to include not just temporal fluctuations but also correlated gain fluctuations across the receiver bandpass. The power spectral density of the spectral gain fluctuations are modelled as a power-law, and characterised by a parameter $\beta$. It is found that the degree of 1/f noise frequency correlation will be critical to the success of HI IM experiments. Small values of $\beta$ ($\beta$ < 0.25) or high correlation is preferred as this is more easily removed using current component separation techniques. The spectral index of temporal fluctuations ($\alpha$) is also found to have a large impact on signal-to-noise. Telescope slew speed has a smaller impact, and a scan speed of 1 deg s$^{-1}$ should be sufficient for a HI IM survey with the SKA.Comment: 22 pages, 15 figures, 2 table