New magnetic and structural results for uniformly spaced, alternatingly spaced, and ladder‐like copper (II) linear chain compounds (invited)

Results of recent synthetic, structural, and magnetic work on exchange coupled copper (II) ions bridged by nonmagnetic ligands are discussed, including the quasi‐linear chain compound bis (dimethyldithiocarbamato) copper (II) in which the copper (II) ions are antiferromagnetically exchange coupled. An unusual correlation exists in the structural and magnetic data for [Cu(dmtc)2]∞ and other known sulfur bridged coppercompounds. Data are presented for the alternatingly spaced linear chain compounds di‐μ‐chlorobis‐(4‐methylpyridine)copper (II), and a series of dionebis‐(thiosemicarbazato)copper (II) compounds. Exchange coupling constants and alternation parameters were obtained from expressions which were empirically generated from calculations on rings of ten S = 1/2 ions for kT/‖J‖≳0.5 and J<0. Finally, new results for recently discovered spin ladder systems are presented

Correlation between π-orbital overlap and conductivity in bis-phthalocyaninato lanthanides

Conductivity measurements on praseodymim, neodymium, gadolinium, holmium, erbium, and lutetium phthalocyanine sandwich compounds of the general formula H[M(Pc) 2)] taken with both D.C. and A.C. techniques on pressed pellet samples show a direct correlation with the intraplanar separation between the phthalocyanine ligands. Conductivity measurements on the iodine-dcped bis-phthalocyaninato lanthanides, H(M(Pc)2I x], show an average increase of four orders of magnitude when measured with D.C. techniques, and two orders of magnitude when measured with A.C. techniques. The high-temperature conductivity behavior may be explained by using the mobility model. The low-temperature data show hopping conduction behavior

Electrical, magnetic and spectroscopic properties of tetrathiafulvalene charge transfer compounds with iron, ruthenium, rhodium and iridium halides

The charge transfer compounds (TTF) FeCl3, (TTF)3FeBr3 , (TTF)RuCl3-2H.0, (TTF)RhCl3.H20, and (TTF)IrCl4-CH3OH were prepared from reaction of solutions of TTF (tetrathiafulvalence) and the metal halide. Magnetic susceptibility and spectroscopic (electronic, vibrational, XPS, and EPR) evidence indicate that there is incomplete charge transfer from the TTF donor to iron, and that there is essentially complete charge transfer to ruthenium, rhodium, and iridium. The experimental evidence indicates that two electrons are transferred in the rhodium compound. The electrical conductivities of powdered samples of the iron compounds are five orders of magnitude greater than those of the ruthenium, rhodium, and iridium compounds, being 6-10 S-cm-'at room temperature. All of the compounds exhibit semiconducting behavior which may be described by a mobility model having a temperature dependent preexponential term and relatively small activation energies

Synthesis and characterization of tetrathiafulvalene charge transfer compounds with copper halides

Charge transfer compounds with the general formula (TTF)4CuX2 (TTF = tetrathiafulvalene; X = Cl, Br) may be prepared by the reaction of excess TTF with Cu(sparteine)X2 in methylene chloride. The semiconducting compounds have low activation energies and relatively high electrical conductivities. Magnetic susceptibility, EPR, and spectroscopic data provide evidence that copper has been reduced to copper(I) in the complexes, and that the unpaired electrons are delocalized over columnar stacks of TTF. Reaction of TTF with [Cu(2-aminoethylpyridine)Cl2] or [Cu(nicotine)C12] in methylene chloride yielded (TTF)2CuCI2, while reaction of TTF with [Cu4OCl6(2-picoline)4] yielded (TTF)CUCI2

Tower and Aircraft Eddy Covariance Measurements of Water Vapor, Energy, and Carbon Dioxide Fluxes during SMACEX

Abstract A network of eddy covariance (EC) and micrometeorological flux (METFLUX) stations over corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] canopies was established as part of the Soil Moisture–Atmosphere Coupling Experiment (SMACEX) in central Iowa during the summer of 2002 to measure fluxes of heat, water vapor, and carbon dioxide (CO2) during the growing season. Additionally, EC measurements of water vapor and CO2 fluxes from an aircraft platform complemented the tower-based measurements. Sensible heat, water vapor, and CO2 fluxes showed the greatest spatial and temporal variability during the early crop growth stage. Differences in all of the energy balance components were detectable between corn and soybean as well as within similar crops throughout the study period. Tower network–averaged fluxes of sensible heat, water vapor, and CO2 were observed to be in good agreement with area-averaged aircraft flux measurements

Effects of alternation in some quasi‐one‐dimensional magnetic materials

Exchange coupling in Cu(II) and Mn(III) compounds with unusual structures is discussed. {[Cu(bipyrimidine)(OH)(H2O)] (ClO4)}n has an alternatingly bridged structure with alternating ferromagnetic (+167.6 cm−1 through the hydroxo bridge) and antiferromagnetic (−79.8 cm−1 through the bipyrimidine bridge) interactions. Copper(II) phthalate monohydrate has alternating next‐nearest‐neighbor exchange with J=−12.3 cm−1 and α=0.06. This is the first member of this class. The compound K2[Mn(III) (salicylate)2][Mn(III) (salicylate)2]{CH3OH]2 has manganese ions in two environments alternating along the chain. A modified model for the chain is presented, and exchange coupling is found to be small since magnetic orbitals are not linked by the bridging ligand.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70701/2/JAPIAU-69-8-6013-1.pd

Copper Accumulation and the Effect of Chelation Treatment on Cerebral Amyloid Angiopathy Compared to Parenchymal Amyloid Plaques

Accumulation of fibrillar amyloid β-protein (Aβ) in parenchymal plaques and in blood vessels of the brain, the latter condition known as cerebral amyloid angiopathy (CAA), are hallmark pathologies of Alzheimer\u27s disease (AD) and related disorders. Cerebral amyloid deposits have been reported to accumulate various metals, most notably copper and zinc. Here we show that, in human AD, copper is preferentially accumulated in amyloid-containing brain blood vessels compared to parenchymal amyloid plaques. In light of this observation, we evaluated the effects of reducing copper levels in Tg2576 mice, a transgenic model of AD amyloid pathologies. The copper chelator, tetrathiomolybdate (TTM), was administered to twelve month old Tg2576 mice for a period of five months. Copper chelation treatment significantly reduced both CAA and parenchymal plaque load in Tg2576 mice. Further, copper chelation reduced parenchymal plaque copper content but had no effect on CAA copper levels in this model. These findings indicate that copper is associated with both CAA deposits and parenchymal amyloid plaques in humans, but less in Tg2576 mice. TTM only reduces copper levels in plaques in Tg2576 mice. Reducing copper levels in the brain may beneficially lower amyloid pathologies associated with AD

Environmental Enrichment: Disentangling the Influence of Novelty, Social, and Physical Activity on Cerebral Amyloid Angiopathy in a Transgenic Mouse Model

Cerebral amyloid angiopathy (CAA) is the deposition of amyloid protein in the cerebral vasculature, a common feature in both aging and Alzheimer’s disease (AD). However, the effects of environmental factors, particularly cognitive stimulation, social stimulation, and physical activity, on CAA pathology are poorly understood. These factors, delivered in the form of the environmental enrichment (EE) paradigm in rodents, have been shown to have beneficial effects on the brain and behavior in healthy aging and AD models. However, the relative importance of these subcomponents on CAA pathology has not been investigated. Therefore, we assessed the effects of EE, social enrichment (SOC), and cognitive enrichment (COG) compared to a control group that was single housed without enrichment (SIN) from 4 to 8 months of age in wild-type mice (WT) and Tg-SwDI mice, a transgenic mouse model of CAA that exhibits cognitive/behavioral deficits. The results show that individual facets of enrichment can affect an animal model of CAA, though the SOC and combined EE conditions are generally the most effective at producing physiological, cognitive/behavioral, and neuropathological changes, adding to a growing literature supporting the benefits of lifestyle interventions

Long-term voluntary wheel running does not alter vascular amyloid burden but reduces neuroinflammation in the Tg-SwDI mouse model of cerebral amyloid angiopathy

Background: Cardiovascular exercise (CVE) has been shown to be protective against cognitive decline in aging and the risk for dementias, including Alzheimer’s Disease (AD). CVE has also been shown to have several beneficial effects on brain pathology and behavioral impairments in mouse models of AD; however, no studies have specifically examined the effects of CVE on cerebral amyloid angiopathy (CAA), which is the accumulation of amyloid-beta (Aβ) in the cerebral vasculature. CAA may be uniquely susceptible to beneficial effects of CVE interventions due to the location and nature of the pathology. Alternatively, CVE may exacerbate CAA pathology, due to added stress on already compromised cerebral vasculature. Methods: In the current study, we examined the effects of CVE over many months in mice, thereby modeling a lifelong commitment to CVE in humans. We assessed this voluntary CVE in Tg-SwDI mice, a transgenic mouse model of CAA that exhibits behavioral deficits, fibrillar vascular Aβ pathology, and significant perivascular neuroinflammation. Various “doses” of exercise intervention (0 h (“Sedentary”), 1 h, 3 h, 12 h access to running wheel) were assessed from ~ 4 to 12 months of age for effects on physiology, behavior/cognitive performance, and pathology. Results: The 12 h group performed the greatest volume of exercise, whereas the 1 h and 3 h groups showed high levels of exercise intensity, as defined by more frequent and longer duration running bouts. Tg-SwDI mice exhibited significant cerebral vascular Aβ pathology and increased expression of pro-inflammatory cytokines as compared to WT controls. Tg-SwDI mice did not show motor dysfunction or altered levels of anxiety or sociability compared to WT controls, though Tg-SwDI animals did appear to exhibit a reduced tendency to explore novel environments. At all running levels, CAA pathology in Tg-SwDI mice was not significantly altered, but 12-h high-volume exercise showed increased insoluble Aβ burden. However, CVE attenuated the expression of pro-inflammatory cytokines TNF-α and IL-6 and was generally effective at enhancing motor function and reducing anxiety-like behavior in Tg-SwDI mice, though alterations in learning and memory tasks were varied. Conclusions: Taken together, these results suggest that CAA can still develop regardless of a lifespan of substantial CVE, although downstream effects on neuroinflammation may be reduced and functional outcomes improved

Particulate-Matter Emission Estimates from Agricultural Spring-Tillage Operations Using LIDAR and Inverse Modeling

Particulate-matter (PM) emissions from a typical spring agricultural tillage sequence and a strip–till conservation tillage sequence in California’s San Joaquin Valley were estimated to calculate the emissions control efficiency (η) of the strip–till conservation management practice (CMP). Filter-based PM samplers, PM-calibrated optical particle counters (OPCs), and a PM-calibrated light detection and ranging (LIDAR) system were used to monitored upwind and downwind PM concentrations during May and June 2008. Emission rates were estimated through inverse modeling coupled with the filter and OPC measurements and through applying a mass balance to the PM concentrations derived from LIDAR data. Sampling irregularities and errors prevented the estimation of emissions from 42% of the sample periods based on filter samples. OPC and LIDAR datasets were sufficiently complete to estimate emissions and the strip–till CMP η, which were ∼90% for all size fractions in both datasets. Tillage time was also reduced by 84%. Calculated emissions for some operations were within the range of values found in published studies, while other estimates were significantly higher than literature values. The results demonstrate that both PM emissions and tillage time may be reduced by an order of magnitude through the use of a strip–till conservation tillage CMP when compared to spring tillage activities