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Search Results: 1 - 10 of 31001 matches for " Thomas Bredow "
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The Effects of Oxidation States, Spin States and Solvents on Molecular Structure, Stability and Spectroscopic Properties of Fe-Catechol Complexes: A Theoretical Study  [PDF]
Mohammad A. Matin, Mazharul M. Islam, Thomas Bredow, Mohammed Abdul Aziz
Advances in Chemical Engineering and Science (ACES) , 2017, DOI: 10.4236/aces.2017.72011
Abstract: In this study, in order to explain the solvent and spin state effects on the molecular structure of catechol-Fe complex [Fe(cat)3]n?where n = 2 and 3, Hartree Fock (HF)-Density Functional Theory (DFT) hybrid calculations are performed at the B3LYP/6-311g(d,p) level of theory. The binding energies of Fe2+ and Fe3+ in high-spin state are higher than intermediate and low-spin states which show that the complex formation in a high spin state is more favorable. The calculated binding energies at different solvents indicate that the binding energies in polar solvents are lower than non-polar solvents. Furthermore, spectroscopic studies including FTIR and Raman spectrum in various solvents reveal that the formation of intermolecular bonds between the oxygen atom of carbonyl group and the hydrogen atom of solvent causes a spectral red shift. The calculated FTIR and geometry parameters are in good agreement with previous experimental data. Donor-acceptor interaction energies are evaluated due to the importance of the charge transfer in the complex formation. It is observed that the free electrons of oxygen atom interact with the antibonding orbitals of the iron. Finally, some correlations between the quantum chemical reactivity indices of the complexes and solvent polarity are considered. The study indicates a linear correlation between chemical hardness and binding energies of [Fe(cat)3]3?complex.
Organometallic Benzene-Vanadium Wire: One-Dimensional Half-Metallic Ferromagnet
Volodymyr V. Maslyuk,Alexei Bagrets,Thomas Bredow,Ingrid Mertig
Physics , 2005, DOI: 10.1103/PhysRevLett.97.097201
Abstract: Using density functional theory we have performed theoretical investigations of the electronic properties of a free-standing one-dimensional organometallic vanadium-benzene wire. This system represents the limiting case of multi-decker V_n(C6H6)_{n+1} clusters which can be synthesized. We predict that the ground state of the wire is a 100% spin-polarized ferromagnet (half-metal). Its density of states is metallic at the Fermi energy for the minority electrons and shows a semiconductor gap for the majority electrons. We found that the half-metallic behavior is conserved up to 12%, longitudinal elongation of the wire. However, under further stretching, the system exhibits a transition to a high-spin ferromagnetic state that is accompanied by an abrupt jump of the magnetic moment and a gain of exchange energy.
Anomalous molecular orbital variation upon adsorption on wide band gap insulator
Wei Chen,Christoph Tegenkamp,Herbert Pfnür,Thomas Bredow
Physics , 2010, DOI: 10.1063/1.3431755
Abstract: It is commonly believed that organic molecules are physisorbed on the ideal non-polar surfaces of wide band gap insulators with limited variation of the electronic properties of the adsorbate molecule. On the basis of first principles calculations within density functional theory (DFT) and $GW$ approximation, we show that this is not generally true. We find that the molecular frontier orbitals undergo significant changes when a hydroxy acid (here we chose gluconic acid) is adsorbed on MgSO$_4$$\cdot$H$_2$O(100) surface due to the complex interaction between the molecule and the insulating surface. The predicted trend of the adsorption effect on the energy gap obtained by DFT is reversed when the surface polarization effect is taken into account via the many-body corrections.
Color centers in NaCl by hybrid functionals
Wei Chen,Christoph Tegenkamp,Herbert Pfnür,Thomas Bredow
Physics , 2010, DOI: 10.1103/PhysRevB.82.104106
Abstract: We present in this work the electronic structure and transition energies (both thermodynamic and optical) of Cl vacancies in NaCl by hybrid density functionals. The underestimated transition energies by the semi-local functional inherited from the band gap problem are recovered by the PBE0 hybrid functional through the non-local exact exchange, whose amount is adjusted to reproduce the experimental band gap. The hybrid functional also gives a better account of the lattice relaxation for the defect systems arising from the reduced self-interaction. On the other hand, the quantitative agreement with experimental vertical transition energy cannot be achieved with hybrid functionals due to the inaccurate descriptions of the ionization energies of the localized defect and the positions of the band edges.
Potential of dispersion of Tecoma stans and chemical attributes of some soils of the Paraná state
Edgard Alfredo Bredow,Celina Wisniewski
CERNE , 2009,
Abstract: This work correlated invasiveness characteristic (potential dispersion) of Tecoma stans (L.) Jussieu ex. Kunth(BIGNONIACEAE) known as a Yellow-Bell. Open field test was developed starting from stakes in vases with four different types soilsof the Paraná State, conduced to randomized block design with four treatments and five replications. The soils were analyzedregarding the pH, CTC, level of C, Al+3, macro and micronutrients, and content of sand, silt and clay. After 6 months the leaf area, dryweight of leaves and potential dispersion, calculated by given numeric values from 1 to 4 for phonological phases presented. Themacro and micronutrients content (except K and Fe) were high in all the soils. The correlations between dispersion potential and pHand the V% were positive and significant and with effective CTC, the Fe and clay content were negative. It was not found significantcorrelations between the dispersion potential and biomass or leaf area. Positive and significant correlations of biomass and leaf areawith macro (except P) and micronutrients (except Cu) apparently indicate that if the evaluation had been accomplished at the end of theflowering period of the species, nutritional relationships with the dispersion potential would be clearer, although it can be concludedthat the species has a preference for less acid soils.
Cutting diameter influence in the rooting of Tecoma stans (L.) Juss. ex Kunth/ Influência do diametro de estacas no enraizamento de Tecoma stans (L.) Juss. ex Kunth
Daniela Biondi,Edgard Alfredo Bredow,Luciana Leal
Semina : Ciências Agrárias , 2008,
Abstract: Tecoma stans (L.) Juss. ex Kunth (Bignoniaceae) is a native tree from the Americas and Antilles and was introduced in Brazil for ornamental reasons, but became an invasive species in degraded areas and pastures in the south region. In Paraná State it is considered a noxious invasive species and its entrance, planting, transport, production and the commerce of its seedlings, seeds, pieces of stem and roots are forbidden. The aim of this research was to prove the rooting ability potential of hardwoody stem cuttings of Tecoma stans with different diameter thickness. The experiment was conducted in a completely randomized design with three treatments: T1 = stem diameter from 0.60 – 0.80 cm, T2 =stem diameter from 0.81 – 1.00 cm and T3 = stem diameter from 1.01 – 1.20 cm. The evaluated variables were: rooting rate, the number of sprouting per cutting, length of sprouting per cutting (cm), cutting rate with more than ten roots and length of the three larger roots formed per cutting (cm). All the cuttings showed 100% of rooting. The T2 and T3 treatments differed statistically from T1 treatment for sprouting length, while T2 differed from the others, for the roots length. The easiness of this species to propagate in a vegetative way reinforces and proves its invasive characteristics. Tecoma stans (L.) Juss. ex Kunth (Bignoniaceae), árvore nativa das Américas e Antilhas, foi introduzida no Brasil para fins ornamentais e tornou-se uma espécie invasora de áreas degradadas e pastagens na regi o sul. No Estado do Paraná é considerada uma planta invasora nociva, proibida a sua entrada, o plantio, o transporte, a produ o e o comércio de mudas, sementes, peda os de caules e raízes. O trabalho teve como objetivo comprovar o potencial de enraizamento de estacas caulinares lenhosas de Tecoma stans com diferentes diametros de espessura. O delineamento utilizado foi inteiramente casualizado com três tratamentos: T1 = diametro da estaca de 0,60 – 0,80 cm; T2 = diametro da estaca de 0,81 – 1,00 cm e T3 = diametro da estaca de 1,01 – 1,20 cm. As variáveis analisadas foram: percentagem de estacas enraizadas, número de brota es por estaca, comprimento das brota es (cm), percentagem de estacas com presen a de mais de 10 raízes e comprimento das 3 maiores raízes por estaca (cm). Todas as estacas apresentaram 100% de enraizamento. Os tratamentos T2 e T3 diferiram estatisticamente do tratamento T1 para o comprimento das brota es, enquanto o T2 diferiu dos demais para o comprimento das raízes. A facilidade desta espécie em propagar-se vegetativamente refor a e comprova a sua cara
Latina mothers feeding their children: A focus group pilot study  [PDF]
James A. Bany, Victoria Lowerson Bredow, Robynn Zender, Susan Tiso, Merry Grasska, Jill Berg
Open Journal of Nursing (OJN) , 2013, DOI: 10.4236/ojn.2013.32029
Abstract:

The purpose of this study was to better understand current knowledge of health and nutrition, barriers to improving eating habits, and preferences for school-based interventions among low-income Latina mothers. Qualitative research methods and analysis were employed. Eighteen mothers of preschool-aged children participated in a focus group interview. Findings indicate that mothers have an understanding of healthy eating, but identified issues with connecting food with weight and in understanding definitions of “obese”. Further, respondents identified barriers to incorporating healthier foods and cooking methods into daily life, due to family food preferences, cultural practices, and schedules. Mother’s concerns about the future weight and the health of their children appeared to motivate interest in improving feeding behaviors. Desired interventions of mothers highlight the importance of culturally relative solutions to behavior change towards healthy eating.

Impairment of Retrograde Neuronal Transport in Oxaliplatin-Induced Neuropathy Demonstrated by Molecular Imaging
Dawid Schellingerhout, Lucia G. LeRoux, Brian P. Hobbs, Sebastian Bredow
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045776
Abstract: Background and Purpose The purpose of our study was to utilize a molecular imaging technology based on the retrograde axonal transport mechanism (neurography), to determine if oxaliplatin-induced neurotoxicity affects retrograde axonal transport in an animal model. Materials and Methods Mice (n = 8/group) were injected with a cumulative dose of 30 mg/kg oxaliplatin (sufficient to induce neurotoxicity) or dextrose control injections. Intramuscular injections of Tetanus Toxin C-fragment (TTc) labeled with Alexa 790 fluorescent dye were done (15 ug/20 uL) in the left calf muscles, and in vivo fluorescent imaging performed (0–60 min) at baseline, and then weekly for 5 weeks, followed by 2-weekly imaging out to 9 weeks. Tissues were harvested for immunohistochemical analysis. Results With sham treatment, TTc transport causes fluorescent signal intensity over the thoracic spine to increase from 0 to 60 minutes after injection. On average, fluorescence signal increased 722%+/?117% (Mean+/?SD) from 0 to 60 minutes. Oxaliplatin treated animals had comparable transport at baseline (787%+/?140%), but transport rapidly decreased through the course of the study, falling to 363%+/?88%, 269%+/?96%, 191%+/?58%, 121%+/?39%, 75%+/?21% with each successive week and stabilizing around 57% (+/?15%) at 7 weeks. Statistically significant divergence occurred at approximately 3 weeks (p≤0.05, linear mixed-effects regression model). Quantitative immuno-fluorescence histology with a constant cutoff threshold showed reduced TTc in the spinal cord at 7 weeks for treated animals versus controls (5.2 Arbitrary Units +/?0.52 vs 7.1 AU +/?1.38, p<0.0004, T-test). There was no significant difference in neural cell mass between the two groups as shown with NeuN staining (10.2+/?1.21 vs 10.5 AU +/?1.53, p>0.56, T-test). Conclusion We show–for the first time to our knowledge–that neurographic in vivo molecular imaging can demonstrate imaging changes in a model of oxaliplatin-induced neuropathy. Impaired retrograde neural transport is suggested to be an important part of the pathophysiology of oxaliplatin-induced neuropathy.
T dlicher Verlauf eines sich peripartal entwickelnden HELLP-Syndroms trotz frühzeitiger Diagnosestellung und Intensivtherapie einschlie lich Implantation einer perkutanen Herz-Lungen-Maschine: Eine Kasuistik
Bredow V,Dahm JB,He?e T,Müllejans B
Journal für Hypertonie , 2004,
Abstract: Aufgrund m glicher schwerwiegender Komplikationen und der hohen Letalit t sind die Geburtshelfer seit seiner Erstbeschreibung darauf fokussiert, das HELLP-Syndrom mit seinem sehr variablen klinischen Erscheinungsbild so frühzeitig wie m glich zu erkennen. Trotz der durch die verschiedenen modernen Therapieans tze deutlich verbesserten Prognose bzw. reduzierten Letalit t stellt dieses Krankheitsbild weiterhin eine lebensbedrohliche Erkrankung dar. Im folgenden berichten wir über den Fall einer 25j hrigen Erstschwangeren mit Geminigravidit t, bei der sich in der 31. Schwangerschaftswoche (SSW) eine Pr eklampsie entwickelte. Wegen zus tzlich kardiotokographisch nicht auszuschlie ender Hypoxie eines Zwillings wurde die prim re Schnittentbindung in der 31 + 2 SSW durchgeführt. Bei zun chst nur moderat ver nderten Laborparametern erfolgte kurze Zeit nach der Geburt die Diagnose eines HELLP-Syndroms. Bereits wenige Stunden sp ter kam es zur Entwicklung eines Multiorganversagens, das trotz Aussch pfung aller intensivtherapeutischen Ma nahmen (einschlie lich Implantation einer perkutanen Herz-Lungen-Maschine) letztlich letal endete. Obwohl im vorliegenden Fall die einzige kausale Therapie des HELLP-Syndroms die Entbindung noch vor der eigentlichen Diagnosestellung erfolgte, die Laborver nderungen zun chst nur gering waren und ungeachtet sofortiger zus tzlicher symptomatischer Therapie entwickelte der klinische Verlauf eine nicht mehr beherrschbare Dynamik.
Selection of rhizobia for Trifolium repens in flooded soil conditions
Jonatas Bredow Alves,Enilson Luiz Saccol de Sá,Aleksander Westphal Muniz
Biotemas , 2012,
Abstract: The Brazilian state of Rio Grande do Sul has approximately 5.4 million hectares of lowland. The introduction of winter forage legumes, such as white clover, can increase the productivity of these lowland areas through biological nitrogen fixation (BNF). However, this benefit can only occur if the legume is associated with rhizobia that can efficiently fix nitrogen under available soil conditions. The objective of this study was to select rhizobia of Rio Grande do Sul soils, which are efficient in BNF when in symbiosis with white clover, and evaluate the tolerance of this symbiosis under flooded soil conditions. The experiment was conducted in a greenhouse, in soil-filled pots, where 14 isolates were evaluated for nitrogen fixation ability under flooded soil conditions. Each treatment was tested under two soil moisture conditions (flooded and field simulated). Flooding significantly reduced the number and nodule weight as well as the production of dry matter and nitrogen accumulation in the shoots of plants inoculated with rhizobia. The effect of soil flooding on BNF varied according the isolate evaluated. The strains CVII, P3 4, T4 and VP16 exhibited high nitrogen fixation efficiency under flooding conditions, surpassing the nitrogen-added control treatment, on nitrogen accumulation in shoots.
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