22 research outputs found
Dimorpholinoacetylene and Its Use for the Synthesis of Tetraaminocyclobutadiene Species
Abstract
The new diaminoacetylene (DAA) dimorpholinoacetylene (3) was prepared from 1,1âdimorpholinoethene (1) by bromination to form the dibromoketene aminal 2, which upon lithiation afforded 3 through a FritschâButtenbergâWiechell rearrangement. Heating 3 at elevated temperatures resulted in a complete conversion into the dimer 1,1,2,4âtetramorpholinoâ1âbutenâ3âyne (4), which was used for the synthesis of fourâmembered cyclic bent allene (CBA) transitionâmetal complexes of the type [(CBA)MLn] (5â7; MLn=AuCl, RhCl(COD), RhCl(CO)2; CBA=1,3,4,4âtetramorpholinoâ1,2âcyclobutadiene; COD=1,5âcyclooctadiene). The reaction of 3 with tetraethylammonium bromide gave 1,2,3,4âtetramorpholinocyclobutenylium bromide (8), which reacted with bromine to form 1,2,3,4âtetra(morpholino)cyclobutenediylium bis(tribromide) (9). Compound 9 represents the first fully characterized compound containing a tetraaminocyclobutadiene dication and displays a nearly planar C4N4 core as shown by Xâray diffraction analysis. Detailed quantum chemical calculations were performed to assess the aromaticity of tetraaminocyclubutadiene dications by employing the Nucleus Independent Chemical Shift (NICS) method and current density analysis
CSF Surfactant Protein Changes in Preterm Infants After Intraventricular Hemorrhage
Introduction: Surfactant proteins (SP) have been shown to be inherent proteins of the
human CNS and are altered during acute and chronic disturbances of CSF circulation.
Aim of the study was to examine the changes of surfactant protein concentrations in CSF
of preterm babies suffering from intraventricular hemorrhage.
Patients and Methods: Consecutive CSF samples of 21 preterm infants with
intraventricular hemorrhages (IVH) and posthemorrhagic hydrocephalus (PHHC) were
collected at primary intervention, after 5â10 days and at time of shunt insertion 50
days after hemorrhage. Samples were analyzed for surfactant proteins A, B, C, and G by
ELISA assays and the results were compared to 35 hydrocephalus patients (HC) without
hemorrhage and 6 newborn control patients.
Results and Discussion: Premature patients with IVH showed a significant elevation
of surfactant proteins SP-A, C, and G compared to HC and control groups: mean
values for the respective groups were SP-A 4.19 vs. 1.08 vs. 0.38 ng/ml. Mean SP-C
3.63 vs. 1.47 vs. 0.48 ng/ml. Mean SP-G 3.86 vs. 0.17 vs. 0.2 ng/ml. SP-A and G
concentrations were slowly falling over time without reaching normal values. SP-C levels
declined faster following neurosurgical interventions and reached levels comparable to
those of hydrocephalus patients without hemorrhage.
Conclusion: Intraventricular hemorrhages of premature infants cause posthemorrhagic
CSF flow disturbance and are associated with highly significant elevations of surfactant
proteins A, C, and G independent of total CSF protein concentrations
Erneuerbare Energien in der Raumplanung. Ein Hindernislauf mit TĂŒcken.
Die Energiewende stellt die Raumplanung vor groĂe Herausforderungen. Insbesondere die Plannung und der Bau von Anlagen zur Gewinnung erneuerbarer Energien sind immer wieder hoch umstritten und selten einfach umzusetzen. Der Sammenband prĂ€sentiert mehrere Seminararbeiten, die unterschiedliche Aspekte zum Thema erörtern und viele Beispiele aus der Praxis darstellen
Die sowjetischen Kriegsgefangenen der Technischen Brigade Mineralöl: Der Einsatz sowjetischer MineralölfachkrÀfte an der Ostfront zwischen Ideologie und wehrwirtschaftlichem Interesse
One of the Wehrmacht's main goals in the Caucasus were the oil fields. A special unit for the Caucasus operation was the "Technische Brigade Mineralöl" (Mineral Oil Technical Brigade). The large volume of surviving files from the TBM allows us to glean new insights into the German prisoner of war system at the brigade level. The treatment of the Soviet petroleum specialists is an absolute exception in the German POW system regarding Soviet POWs. The article traces the reasons for this at the intersection of ideology and pragmatism. The files, when viewed as a whole, enable us to make statements about the TBM POWs over the course of their existence. Furthermore, the special treatment of petroleum specialists is contextualized within the broader military-economic environment of the Wehrmacht
Neuropathological findings suggestive for a stroke in an alpaca (Vicugna pacos)
Abstract Background This case report describes a focal brain lesion in an alpaca (Vicugna pacos). Although this is a restricted study based on a single animal, neuropathological features are reported that are most likely attributed to a vascular event with either ischemic or hemorrhagic pathology. Concerning translational issues, these findings extend neurovascular unit concept to the alpacasâ brain and qualify a larger panel of stroke tissue markers for further exploration of ischemic or hemorrhagic consequences beyond the usually used small animal models in stroke research. Case presentation A brain lesion indicative of a stroke was diagnosed in a 3-year-old female alpaca as an incidental finding during a post mortem examination. The rostral portion of the right frontal lobe contained a 1.0âĂâ1.5âĂâ1.7 cm lesion that extended immediately to the overlying leptomeninges. Microscopically, it was composed of liquefactive necrosis with cholesterol crystal deposition and associated granulomatous inflammation as well as vascularized fibrous connective tissue rimmed by proliferated astrocytes. Multiple fluorescence labeling of the affected brain regions revealed strong microgliosis as shown by immunostaining of the ionized calcium binding adapter molecule 1 and astrogliosis as demonstrated by enhanced immunoreactivity for glial fibrillary acidic protein. In parallel, a drastic neuronal loss was detected by considerably diminished immunolabeling of neuronal nuclei. Concomitantly, up-regulated immunoreactivities for collagen IV and neurofilament light chains were found in the affected tissues, indicating vascular and cytoskeletal reactions. Conclusions Driven by these neuropathological features, the incidental brain lesion found in this alpaca strongly suggests an ischemic or hemorrhagic etiology. However, since typical hallmarks became verifiable as previously described for other species affected by focal cerebral ischemia, the lesion is more likely related to an ischemic event. Nevertheless, as such cellular alterations might be difficult to distinguish from other brain lesions as for instance caused by inflammatory processes, adjuvant observations and species-related features need to be considered for etiological interpretations. Indeed, the lack of neurological deficits is likely attributed to the location of the lesion within the rostral aspect of the right frontal lobe of the alpacasâ brain. Further, fibroblast migration from the meninges likely caused the intralesional scar formation
Behavior of highly diluted electrolytes in strong electric fields : prevention of alumina deposition on grading electrodes in HVDC transmission modules by -induced pH-control
Alumina deposition on platinum grading electrodes in high voltage direct current (HVDC) transmission modules is an unsolved problem that has been around for more than three decades. This is due to the unavoidable corrosion of aluminum heat sinks that causes severe damage to electrical power plants and losses in the range of a million Euro range per day in power outage. Simple experiments in a representative HV test setup showed that aluminates at concentrations even below 10â8â
molâLâ1 can deposit on anodes through neutralization by protons produced in de-ionized water (Îșâ€0.15â
ÎŒSâcmâ1) at 20â35â
kV (8â
mA) per electrode. In this otherwise electrolyte-poor aqueous environment, the depositions are formed three orders of magnitude below the critical precipitation concentration at pHâ
7! In the presence of an inert electrolyte such as TMAT (tetramethylammonium-p-toluenesulfonate), at a concentration level just above that of the total dissolved aluminum, no deposition was observed. Deposition can be also prevented by doping with CO2 gas at a concentration level that is magnitudes lower than that of the dissolved aluminum. From an overview of aqueous aluminum chemistry, the mystery of the alumina deposition process and its inhibition by CO2 is experimentally resolved and fully explained by field accumulation and repulsion models in synergism with acidâbase equilibria. The extraordinary size of the alumina depositions is accounted for in terms of proton tunneling through âhydratedâ alumina, which is supported by quantum chemical calculations. As a consequence, pulse-purging with pure CO2 gas is presented as a technical solution to prevent the deposition of alumina