2,768 research outputs found
[3+2] Fragmentation of a Pentaphosphido Ligand by Cyanide
The activation of white phosphorus (P4) by transitionâmetal complexes has been studied for several decades, but the functionalization and release of the resulting (organo)phosphorus ligands has rarely been achieved. Herein we describe the formation of rare diphosphanâ1âide anions from a P5 ligand by treatment with cyanide. Cobalt diorganopentaphosphido complexes have been synthesized by a stepwise reaction sequence involving a lowâvalent diimine cobalt complex, white phosphorus, and diorganochlorophosphanes. The reactions of the complexes with tetraalkylammonium or potassium cyanide afford a cyclotriphosphido cobaltate anion 5 and 1âcyanodiphosphanâ1âide anions [R2PPCN]â (6âR). The molecular structure of a related product 7 suggests a novel reaction mechanism, where coordination of the cyanide anion to the cobalt center induces a ligand rearrangement. This is followed by nucleophilic attack of a second cyanide anion at a phosphorus atom and release of the P2 fragment
Bone density as a marker for local response to radiotherapy of spinal bone metastases in women with breast cancer: a retrospective analysis
Background: We designed this study to quantify the effects of radiotherapy (RT) on bone density as a local response in spinal bone metastases of women with breast cancer and, secondly, to establish bone density as an accurate and reproducible marker for assessment of local response to RT in spinal bone metastases. Methods: We retrospectively assessed 135 osteolytic spinal metastases in 115 women with metastatic breast cancer treated at our department between January 2000 and January 2012. Primary endpoint was to compare bone density in the bone metastases before, 3 months after and 6 months after RT. Bone density was measured in Hounsfield units (HU) in computed tomography scans. We calculated mean values in HU and the standard deviation (SD) as a measurement of bone density before, 3 months and 6 months after RT. T-test was used for statistical analysis of difference in bone density as well as for univariate analysis of prognostic factors for difference in bone density 3 and 6 months after RT. Results: Mean bone density was 194.8 HUâ±âSD 123.0 at baseline. Bone density increased significantly by a mean of 145.8 HUâ±âSD 139.4 after 3 months (pâ=â.0001) and by 250.3 HUâ±âSD 147.1 after 6 months (pâ<.0001). Women receiving bisphosphonates showed a tendency towards higher increase in bone density in the metastases after 3 months (152.6 HUâ±âSD 141.9 vs. 76.0 HUâ±âSD 86.1; pâ=â.069) and pathological fractures before RT were associated with a significantly higher increase in bone density after 3 months (202.3 HUâ±âSD 161.9 vs. 130.3 HUâ±âSD 129.2; pâ=â.013). Concomitant chemotherapy (ChT) or endocrine therapy (ET), hormone receptor status, performance score, applied overall RT dose and prescription of a surgical corset did not correlate with a difference in bone density after RT. Conclusions: Bone density measurement in HU is a practicable and reproducible method for assessment of local RT response in osteolytic metastases in breast cancer. Our analysis demonstrated an excellent local response within metastases after palliative RT
âIâll Take the EâScooter Instead of My Carâ - The Potential of EâScooters as a Substitute for Car Trips in Germany
Considering the controversial discussion about the sustainability and usefulness of eâ
scooters, in this study, we analyzed the substitution potential of eâscooters, especially with regard
to car trips. Based on data from the national mobility survey in Germany (Mobility in Germany,
MiD 2017), we identified trips that could be covered purely by an eâscooter. Thereby, trip length, trip purposes, weather conditions, and other influencing factors were taken into account. Our analâ
ysis showed that, in Germany, 10â15% of the motorized individual transport (MIT) trips could be made by eâscooter. Accompanied by a literature analysis, we then critically reflected on the overall potential of eâscooters and formulated recommendations for urban and transport planning
Oslo: autoarme Innenstadt mit Fokus auf Partizipation
In der norwegischen Hauptstadt Oslo wurden im Rahmen des sogenannten âCar-free Livability Programme 2019â zwischen 2017 und 2019 zahlreiche öffentliche StraĂenparkplĂ€tze im Zentrum entfernt. Die MaĂnahmen zielen darauf ab, den privaten Pkw-Verkehr zu reduzieren und die FlĂ€chen der ehemals öffentlichen StraĂenparkplĂ€tze alternativen Nutzungen zuzufĂŒhren. Durch Pflanzungen von StraĂenbĂ€umen, das Aufstellen von PflanzenkĂŒbeln und Stadtmobiliar wurden neue AufenthaltsflĂ€chen geschaffen, welche die AttraktivitĂ€t der Innenstadt steigern sollen.
Um auch den motorisierten Durchgangsverkehr aus dem Stadtzentrum auszuschlieĂen, wurden in einem weiteren Schritt bestimmte StraĂen fĂŒr den motorisierten Individualverkehr geschlossen. Parallel zu den MaĂnahmen, die auf die EinschrĂ€nkung des privaten Pkw-Verkehrs abzielen, wurden im Gegenzug MaĂnahmen zur Förderung aktiver Modi auf den Weg gebracht.
Diese beinhalteten unter anderem den Ausbau des FuĂ- und Radwegenetzes, die Einrichtung von FuĂgĂ€ngerstraĂen und von Shared-Space-Bereichen sowie eine Aufwertung des öffentlichen Raums durch temporĂ€re und permanente Umgestaltungen.
Durch die Verminderung des MIV und die Umwidmung von StraĂenflĂ€chen zugunsten der aktiven Modi sowie der AufenthaltsqualitĂ€t sollen alternative Nutzungen des öffentlichen Raumes begĂŒnstigt, die stĂ€dtische LebensqualitĂ€t gesteigert und ein Beitrag zu Minderung der stĂ€dtischen CO2-Emissionen geleistet werden. Um erwarteten Vorbehalten aus Teilen der Bevölkerung sowie der lokalen Wirtschaft zu begegnen, wurden die MaĂnahmen von Beginn anvon einer umfangreichen BĂŒrgerbeteiligung mit gezielten Informationskampagnen und Partizipationsmöglichkeiten begleitet.
In der Folge ist die Zufriedenheit mit den MaĂnahmen sowohl bei den Verkehrsteilnehmenden selbst als auch bei den Stadtverantwortlichen und lokalen GeschĂ€ftstreibenden hoch. Im Modal Split im Zielverkehr ergaben sich durch die umgesetzten MaĂnahmen geringe Verschiebungen hin zum Umweltverbund. Der Durchgangsverkehr wird weitestgehend aus dem MaĂnahmengebiet herausgehalten, so dass sich eine deutliche Reduzierung des Verkehrsaufkommens ergibt. Insbesondere durch zu FuĂ Gehende wird das Stadtzentrum nun viel stĂ€rker belebt
Second harmonic generation from strongly coupled localized and propagating phonon-polariton modes
We experimentally investigate second harmonic generation from strongly
coupled localized and propagative phonon polariton modes in arrays of silicon
carbide nanopillars. Our results clearly demonstrate the hybrid nature of the
system's eigenmodes and distinct manifestation of strong coupling in the linear
and nonlinear response. While in linear reflectivity the intensity of the two
strongly-coupled branches is essentially symmetric and well explained by their
respective localized or propagative components, the second harmonic signal
presents a strong asymmetry. Analyzing it in detail, we reveal the importance
of interference effects between the nonlinear polarization terms originating in
the bulk and in the phonon polariton modes, respectively.Comment: 7 pages, 4 figure
Transition Metal-Mediated Functionalization of White Phosphorus
Recently there has been great interest in the reactivity of transitionâmetal (TM) centers towards white phosphorus (P4). This has ultimately been motivated by a desire to find TMâmediated alternatives to the current industrial routes used to transform P4 into myriad useful Pâcontaining products, which are typically indirect, wasteful, and highly hazardous. Such a TMâmediated process can be divided into two steps: activation of P4 to generate a polyphosphorus complex TMâPn, and subsequent functionalization of this complex to release the desired phosphorusâcontaining product. The former step has by now become well established, allowing the isolation of many different TMâPn products. In contrast, productive functionalization of these complexes has proven extremely challenging and has been achieved only in a relative handful of cases. In this review we provide a comprehensive summary of successful TMâPn functionalization reactions, where TMâPn must be accessible by reaction of a TM precursor with P4. We hope that this will provide a useful resource for continuing efforts that are working towards this highly challenging goal of modern synthetic chemistry
The proteome of human brain microdialysate
BACKGROUND: Cerebral microdialysis has been established as a monitoring tool in neurocritically ill patients suffering from severe stroke. The technique allows to sample small molecules in the brain tissue for subsequent biochemical analysis. In this study, we investigated the proteomic profile of human cerebral microdialysate and if the identified proteins might be useful predictors for disease characteristics in stroke for tissue at risk in the contralateral hemisphere. We analysed cerebral protein expression in microdialysate from three stroke patients sampled from the hemisphere contralateral to the lesion. Using a proteomic approach based on two-dimensional gel electrophoresis and subsequent mass spectrometry, we created a protein map for the global protein expression pattern of human microdialyste. RESULTS: We found an average of 158 ± 24 (N = 18) protein spots in the human cerebral microdialysate and could identify 95 spots, representing 27 individual proteins. Most of these have been detected in human cerebrospinal fluid before, but 10 additional proteins mainly of cerebral intracellular origin were identified exclusively in the microdialysate. CONCLUSIONS: The 10 proteins found exclusively in human cerebral microdialysate, but not in cerebrospinal fluid, indicate the possibility to monitor the progression of the disease towards deterioration. The correlation of protein composition in the human cerebral microdialysate with the patients' clinical condition and results of cerebral imaging may be a useful approach to future applications for neurological stroke diagnosis, prognosis, and treatment
Impact of cannabis use on brain metabolism using 31P and 1H magnetic resonance spectroscopy
Purpose This prospective cross-sectional study investigated the infuence of regular cannabis use on brain metabolism in
young cannabis users by using combined proton and phosphorus magnetic resonance spectroscopy.
Methods The study was performed in 45 young cannabis users aged 18â30, who had been using cannabis on a regular basis
over a period of at least 2 years and in 47 age-matched controls. We acquired 31P MRS data in diferent brain regions at 3T
with a double-resonant 1H/31P head coil, anatomic images, and 1H MRS data with a standard 20-channel 1H head coil.
Absolute concentration values of proton metabolites were obtained via calibration from tissue water as an internal reference, whereas a standard solution of 75 mmol/l KH2PO4 was used as an external reference for the calibration of phosphorus
signals.
Results We found an overall but not statistically signifcant lower concentration level of several proton and phosphorus
metabolites in cannabis users compared to non-users. In particular, energy-related phosphates such as adenosine triphosphate
(ATP) and inorganic phosphate (Pi) were reduced in all regions under investigation. Phosphocreatine (PCr) showed lowered
values mainly in the left basal ganglia and the left frontal white matter.
Conclusion The results suggest that the increased risk of functional brain disorders observed in long-term cannabis users
could be caused by an impairment of the energy metabolism of the brain, but this needs to be verifed in future studies
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