2,922 research outputs found
Synthesis, Characterization, and Oxygenation Studies of Carboxylate-Bridged Diiron(II) Complexes with Aromatic Substrates Tethered to Pyridine Ligands and the Formation of a Unique Trinuclear Complex
No full textIn this study, diiron(II) complexes were synthesized as small molecule mimics of the reduced active sites in the hydroxylase components of bacterial multicomponent monooxygenases (BMMs). Tethered aromatic substrates were introduced in the form of 2-phenoxypyridines, incorporating hydroxy and methoxy functionalities into windmill-type diiron(II) compounds [Fe[subscript 2](μ-O[subscript 2]CAr[superscript R])[subscript 2](O[subscript 2]CAr[superscript R])[subscript 2](L)[subscript 2]] (1–4), where[superscript –]O[subscript 2]CAr[superscript R] is a sterically encumbering carboxylate, 2,6-bis(4-fluorophenyl)-, or 2,6-bis(p-tolyl)benzoate (R = 4-FPh or Tol, respectively). The inability of 1–4 to hydroxylate the aromatic substrates was ascertained. Upon reaction with dioxygen, compounds 2 and 3 (L = 2-(m-MeOPhO)Py, 2-(p-MeOPhO)Py, respectively) decompose by a known bimolecular pathway to form mixed-valent diiron(II,III) species at low temperature. Use of 2-(pyridin-2-yloxy)phenol as the ligand L resulted in a doubly bridged diiron complex 4 and an unprecedented phenoxide-bridged triiron(II) complex 5 under slightly modified reaction conditions.National Institute of General Medical Sciences (U.S.) (Grant GM032134
Current challenges of modeling diiron enzyme active sites for dioxygen activation by biomimetic synthetic complexes
No full textThis tutorial review describes recent progress in modeling the active sites of carboxylate-rich non-heme diiron enzymes that activate dioxygen to carry out several key reactions in Nature. The chemistry of soluble methane monooxygenase, which catalyzes the selective oxidation of methane to methanol, is of particular interest for (bio)technological applications. Novel synthetic diiron complexes that mimic structural, and, to a lesser extent, functional features of these diiron enzymes are discussed. The chemistry of the enzymes is also briefly summarized. A particular focus of this review is on models that mimic characteristics of the diiron systems that were previously not emphasized, including systems that contain (i) aqua ligands, (ii) different substrates tethered to the ligand framework, (iii) dendrimers attached to carboxylates to mimic the protein environment, (iv) two N-donors in a syn-orientation with respect to the iron–iron vector, and (v) a N-rich ligand environment capable of accessing oxygenated high-valent diiron intermediates.National Institute of General Medical Sciences (U.S.) (grant GM032134)Engineering and Physical Sciences Research Council (EP/H00338X/1
Subtle Modification of 2,2-Dipicolylamine Lowers the Affinity and Improves the Turn-On of Zn(II)-Selective Fluorescent Sensors
No full textThe spectroscopic and proton- and Zn(II)-binding properties of two new members of the Zinpyr family of fluorescent sensors are reported. In ZP1B and ZP3B, a (2-picolyl)(4-picolyl)amine (2,4-DPA) moiety is installed in place of the di(2-picolyl)amine (2,2-DPA) ligand used in the parent sensors ZP1 and ZP3. This modification has the benefit of both lowering the proton-induced turn-on at physiological pH levels and altering the Zn(II) affinity so as to detect only the most concentrated stores of this ion in biological samples. Comparison of the proton affinities of all four probes, as determined by potentiometric titrations, contributes to our understanding of the solution properties of this family of sensors.National Institute of General Medical Sciences (U.S.) (Grant GM065519)National Institutes of Health (U.S.) (Grant 1S10RR13886-01
Solution and Fluorescence Properties of Symmetric Dipicolylamine-Containing Dichlorofluorescein-Based Zn[superscript 2+] Sensors
No full textThe mechanism by which dipicolylamine (DPA) chelate-appended fluorophores respond to zinc was investigated by the synthesis and study of five new analogues of the 2′,7′-dichlorofluorescein-based Zn[superscript 2+] sensor Zinpyr-1 (ZP1). With the use of absorption and emission spectroscopy in combination with potentiometric titrations, a detailed molecular picture has emerged of the Zn[superscript 2+] and H[superscript +] binding properties of the ZP1 family of sensors. The two separate N[subscript 3]O donor atom sets on ZP1 converge to form binding pockets in which all four heteroatoms participate in coordination to either Zn[superscript 2+] or protons. The position of the pyridyl group nitrogen atom, 2-pyridyl or 4-pyridyl, has a large impact on the fluorescence response of the dyes to protons despite relatively small changes in pK[subscript a] values. The fluorescence quenching effects of such multifunctional electron-donating units are often taken as a whole. Despite the structural complexity of ZP1, however, we provide evidence that the pyridyl arms of the DPA appendages participate in the quenching process, in addition to the contribution from the tertiary nitrogen amine atom. Potentiometric titrations reveal ZP1 dissociation constants (K[subscript d]) for Zn[superscript 2+] of 0.04 pM and 1.2 nM for binding to the first and second binding pockets of the ligand, respectively, the second of which correlates with the value observed by fluorescence titration. This result demonstrates that both binding pockets of this symmetric, ditopic sensor need to be occupied in order for full fluorescence turn-on to be achieved. These results have significant implications for the design and implementation of fluorescent sensors for studies of mobile zinc ions in biology.National Institute of General Medical Sciences (U.S.) (Grant GM065519)National Institutes of Health (U.S.) (Grant 1S10RR13886-01
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
“I beg you to tell me what has become of Djamila”: The Political Mobilization of Simone de Beauvoir’s Readers During the Boupacha Affair
No full textBy Sophia Millman This is a condensed version of a Masters thesis dedicated to the political mobilization of Simone de Beauvoir’s readers. The citations from the letters were translated from French by the author. *** On June 2, 1960, the French government ordered all copies of the daily Algiers edition of Le Monde seized and destroyed to suppress the publication of Simone de Beauvoir’s article “Pour Djamila Boupacha.” Beauvoir, a self-professed “woman of letters”, not “of action[1]”, and one ..
Electronic Structure of a Paramagnetic {MNO}6 Complex: MnNO 5,5-Tropocoronand
No full textUsing density functional theory (OLYP/STO-TZP) calculations, we have investigated the electronic structure of [Mn(5,5-tropocoronand)(NO)], a rare paramagnetic {MNO}6 complex. Experimental methods, including magnetic susceptibility measurements and high-field electron paramagnetic resonance spectroscopy, have not provided an unambiguous spin state assignment for this complex. In other respects, however, the compound was fully characterized, including by means of single-crystal X-ray structure determination. The optimized S = 1 OLYP geometry reproduced all key aspects of the trigonal-bipyramidal molecular structure, including a short Mn-N(O) distance (∼1.7 A° ) and an essentially linear MnNO angle. In contrast, the S = 0 and S = 2 optimized structures disagreed with the crystal structure in critical respects. Moreover, three different exchange-correlation functionals (OLYP, B3LYP, and B3LYP*) indicated an S = 1 ground state by a clear margin of energy. An examination of the Kohn-Sham MOs of this state indicated a primarily dxz 2dyz 2dxy 1dx2-z2 1 electronic configuration, where the z axis is identified with the nearly linear MnNO axis. The dy2 orbital is formally unoccupied in this state, interacting, as it does, head-on with two tropocoronand nitrogens lying along the y axis, the pseudo-3-fold axis of the trigonal bipyramid. The doubly occupied dxz and dyz orbitals are in actuality dπ(Fe)-pi*(NO)-based pi-bonding molecular orbitals, the R and β “components” of which are significantly offset spatially. This offset results in excess minority spin density on the NO unit. Thus, the OLYP/TZP atomic spin populations are Mn, 2.85; N(O), -0.52; and O, -0.35.Norges forskningsrådNational Science Foundation (U.S.)National Research Foundation (South Africa)National Science Foundation (U.S.) (Cooperative Agreement DMR 0654118)United States. Dept. of EnergyNational High Magnetic Field Laboratory (NHMFL UCGP 5062)Florid
A comparative study of form and theology in the works of Flannery O'Connor and Simone Weil
No full textIn this comparative study of the form and theology of Flannery O'Connor and Simone Weil I interrogate how Weil's philosophical writings and her theology illuminate O'Connor's use of both narrative and non-fictional forms, and her Catholicism. The Introduction analyses how Weil's concept of superposed reading provides a new method of approaching both O'Connor, her writings, and O'Connor
studies, and focuses on how such apparently different women interconnect. Chapter One explores how both Weil and O'Connor attempt to write their theologies on the
souls of their readers yet are each subject to constraints imposed by form. Weil's concept of locating equilibrium between incommensurates is discussed, and her
distinctively philosophical approach to fictions and fictionality is used to investigate O'Connor's notion of prophetic fictions and the writer's role. Chapter Two assesses how both writers revivify Christian paradoxes. Weil's monstrous concept of affiiction, and O'Connor's use of the grotesque genre to jolt secular man into an
awareness of the sacred are scrutinised. Chapter Three studies how both writers consider an encounter between God and man is possible through the action of grace. My Conclusion interrogates how Weil's work can deepen our understanding of O'Connor's writings, and examines how successful O'Connor is at realising a truly
Christian literature. I conclude that despite being a writer of powerful fictions, O'Connor can not be totally successful in her mission as writer-prophet because
ultimately fiction escapes orthodoxy
Microlinices benthovus Simone 2014
No full textbenthovus, Microlinices Simone, 2014 Microlinices benthovus Simone, 2014: 575–578 (figs 6A–J, 7A–H, 11A–C). Gastropoda, Naticidae Paratypes (22 spc): MZSP 105269. Paratypes 1 (15 spc): MZSP 105270. Paratypes 2 (16 spc): MZSP 105271. Paratypes 3 (7 spc): MZSP 105272. Localities: Brazil, Espírito Santo, off Itaúnas, Abrolhos Slope, 18°59' S, 37°50' W, MD55 sta. DC 73, 637 m depth, 27 May 1987; 1) 19°00' S, 37°48' W, MD55 sta. DC72, 950– 1050 m, 27 May 1987; 2) off Regência, 19°40' S, 37°48' W, MD55 sta. CB77, 790– 940 m depth, 27 May 1987; 3) off Itaúnas, Abrolhos Slope, 19°01' S, 37°47' W, MD55 sta. CB79, 1500–1575 m depth, 28 May 1987. Collectors: P. Bouchet, J.H. Leal and B. Métivier. Preservation: Dry. Remarks: Former MNHN, Paris. The catalogue number MZSP 105250 is mentioned twice in Simone’s (2014) paper, among the paratypes of M. ibitingus Simone, 2014 and M. benthovus. This duplicity was a mistake by the author: the latter is an erroneous designation and should be disregarded. The only valid paratype lots for M. benthovus are the ones shown above.Published as part of Cavallari, Daniel C., Dornellas, Ana Paula S. & Simone, Luiz Ricardo L., 2016, Second annotated list of type specimens of molluscs deposited in the Museu de Zoologia da Universidade de São Paulo, Brazil, pp. 1-59 in European Journal of Taxonomy 213 on page 10, DOI: 10.5852/ejt.2016.213, http://zenodo.org/record/384012
Was bringt die Föderalismusreform? Wahrscheinliche Effekte der geänderten Zustimmungspflicht
No full textThe recently enacted reform of German federalism is supposed to make legislation faster, more efficient and better. To what extent are these expectations justified? In order to assess the likely effects of the reform, this study uses a research design that was recently applied by the Research and Reference Services of the German Bundestag (parliament): we estimate the future effects of the reform by analyzing the impact it would have had on the legislation in the 14th and 15th term of the Bundestag if it had already been been in force at that time. In particular we ask: To what extent would the number of laws requiring the consent of the states' chamber, the Bundesrat, have been reduced? Which type of laws would have been affected by this reduction - the more controversial ones, or the less controversial ones? Which policy sectors would have seen the greatest reduction? How much would the reduction have increased the government's capacity to act effectively? Would the legislative process have been accelerated? -- Die verabschiedete Föderalismusreform soll die Gesetzgebung in Deutschland schneller, effizienter und besser machen. Inwiefern sind diese Erwartungen berechtigt? Zur Abschätzung der Reformfolgen auf die Bundesgesetzgebung folgen wir in dem vorliegenden Working Paper einer Vorgehensweise, die der Wissenschaftliche Dienst des Bundestages kürzlich in einer Studie angewandt hat: Die Auswirkungen der Föderalismusreform insbesondere auf die Zustimmungspflicht werden anhand der Gesetzgebung der 14. und 15. Legislaturperiode untersucht. Wir fragen insbesondere: Wie stark hätte sich der Anteil der Zustimmungsgesetze verringert, wenn die neuen Zustimmungsregeln schon in diesen beiden Legislaturperioden gegolten hätten? Wären eher zwischen Regierung strittige oder unstrittige Gesetze von der Zustimmungspflicht befreit worden? Welche Politikbereiche wären betroffen? Wie sehr hätte sich die politische Handlungsfreiheit der Bundesregierung erhöht? Wäre die Gesetzgebung durch die veränderten Zustimmungsregeln beschleunigt worden?
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