15 research outputs found
Scientometric analysis of synchronous references in the Physics Nobel lectures, 1981-1985 : a pilot study
No full textScientometric analysis of synchronous references in the nine Physics Nobel lectures by Nicolaas Bloembergen (1981), Arthur L. Schawlow (1981), Kai M. Siegbahn (1981), Kenneth G. Wilson (1982), Subrahmanyan Chandrasekhar (1983), William A. Fowler (1983), Carlo Rubbia (1984), Simon van der Meer (1984), and Klaus von Klitzing (1985) indicated high variations: No. of Synchronous References ranged from 24 (Meer) to 283 (Siegbahn); Synchronous Self-References ranged from 5 (Rubbia) to 88 (Siegbahn); synchronous references to others ranged from 10 (Chandrasekhar) to 255 (Wilson); Synchronous Self-Reference Rates ranged from 6.66 % (Rubbia) to 65.51 % (Chandrasekhar); Single-Authored References ranged from 15 (Klitzing) to 160 (Wilson); Multi-Authored References ranged from 4 (Chandrasekhar) to 194 (Siegbahn); Collaboration Coefficient in the synchronous references ranged from 0.14 (Chandrasekhar) to 0.75 (Klitzing); and Recency (age of 50 % of the latest references) ranged from 2 (Klitzing) to 18 (Chandrasekhar) years. Seventy five per cent of the references belonged to journal articles. Highly referred journals were Astrophysical Journal, Physical Review B, Physical Review Letters, Arkiv Fuer Fysik, Surface Science, Physics Letters, and IEEE Transactions on Nuclear Science.
See: Scientometrics Vol. 61 No.1, pp.55-68
Mechanism of substrate inhibition in cytochrome-c dependent NO reductases from denitrifying bacteria (cNORs)
No full textSteady-state kinetics of cytochrome-c dependent denitrifying NO reductases (cNORs) show evidence of substrate inhibition at NO concentrations higher than 10 μM, but the mechanism of inhibition remains unclear. Here, we present low-temperature FTIR photolysis experiments carried out on the NO complex formed by addition of NO to the oxidized cNORs. A differential signal at 1261 cm−1 that downshifts with 15NO and 15N18O is assigned to a ν(NO2) from a bridging diiron-nitrito complex at the heme-nonheme diron site. Theoretical calculations reproduces observed frequencies and isotope shifts. Our experimental results confirm a prior theoretical study by Blomberg and Siegbahn [Blomberg, M. R., and Siegbahn, P. E. M. Biochemistry 2012, 51, 5173–5186] that proposed substrate inhibition through a radical combination reaction between the diferric μ-oxo group and an NO molecule to form a heme Fe(III)-nitrito-FeB(II) inhibitory complex. Stopped-flow experiments suggest that substrate inhibition also occurs after a half-reduction cycle, i.e. when fully-reduced cNOR reduces two NO molecules at the heme-nonheme diferrous active site cluster to produce one N2O molecule and the diferric cluster. These results support catalytic mechanisms that proceed through isomerization of a diferric-hyponitrite transient complex to produce a bridging diferric μ-oxo group and N2O without protonation of the putative hyponitrite intermediate.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Biocatalysi
Uppsala and Berkeley : Two essential laboratories in the development of modern photoelectron spectroscopy
No full textThe development of modern photoelectron spectroscopy is reviewed with a special focus on the importance of research at Uppsala University and at Berkeley. The influence of two pioneers, Kai Siegbahn and Dave Shirley, is underlined. Early interaction between the two centers helped to kick-start the field. Both laboratories have continued to play an important role in the field, both in terms of creating new experimental capabilities and developing the theoretical understanding of the spectroscopic processes. (C)2022 Author(s)
ExoMol line lists - III. An improved hot rotation-vibration line list for HCN and HNC
No full textA revised rotation-vibration line list for the combined hydrogen cyanide (HCN)/hydrogen isocyanide (HNC) system is presented. The line list uses ab initio transition intensities calculated previously and extensive data sets of recently measured experimental energy levels. The resulting line list has significantly more accurate wavelengths than previous ones for these systems. An improved value for the separation between HCN and HNC is adopted, leading to an approximately 25 per cent lower predicted thermal population of HNC as a function of temperature in the key 2000 to 3000 K region. Temperature-dependent partition functions and equilibrium constants are presented. The line lists are validated by comparison with laboratory spectra and are presented in full as supplementary data to the article and at www.exomol.com
Angiotensin II induces soluble fms-Like tyrosine kinase-1 release via calcineurin signaling pathway in pregnancy
No full textMaternal endothelial dysfunction in preeclampsia is associated with increased soluble fms-like tyrosine kinase-1 (sFlt-1), a circulating antagonist of vascular endothelial growth factor and placental growth factor. Angiotensin II (Ang II) is a potent vasoconstrictor that increases concomitant with sFlt-1 during pregnancy. Therefore, we speculated that Ang II may promote the expression of sFlt-1 in pregnancy. Here we report that infusion of Ang II significantly increases circulating levels of sFlt-1 in pregnant mice, thereby demonstrating that Ang II is a regulator of sFlt-1 secretion in vivo. Furthermore, Ang II stimulated sFlt-1 production in a dose- and time-dependent manner from human villous explants and cultured trophoblasts but not from endothelial cells, suggesting that trophoblasts are the primary source of sFlt-1 during pregnancy. As expected, Ang II-induced sFlt-1 secretion resulted in the inhibition of endothelial cell migration and in vitro tube formation. In vitro and in vivo studies with losartan, small interfering RNA specific for calcineurin and FK506 demonstrated that Ang II-mediated sFlt-1 release was via Ang II type 1 receptor activation and calcineurin signaling, respectively. These findings reveal a previously unrecognized regulatory role for Ang II on sFlt-1 expression in murine and human pregnancy and suggest that elevated sFlt-1 levels in preeclampsia may be caused by a dysregulation of the local renin/angiotensin system
Monadic Second-Order Logic and Bisimulation Invariance for Coalgebras
No full textGeneralizing standard monadic second-order logic for Kripke models, we introduce monadic second-order logic MSO(T) interpreted over co algebras for an arbitrary set functor T. Similar to well-known results for monadic second-order logic over trees, we provide a translation of this logic into a class of automata, relative to the class of T-co algebras that admit a tree-like supporting Kripke frame. We then consider invariance under behavioral equivalence of MSO(T)-formulas, more in particular, we investigate whether the co algebraic mu-calculus is the bisimulation-invariant fragment of MSO(T). Building on recent results by the third author we show that in order to provide such a co algebraic generalization of the Janin-Walukiewicz Theorem, it suffices to find what we call an adequate uniform construction for the functor T. As applications of this result we obtain a partly new proof of the Janin-Walukiewicz Theorem, and bisimulation invariance results for the bag functor (graded modal logic) and all exponential polynomial functors. Finally, we consider in some detail the monotone neighborhood functor M, which provides co algebraic semantics for monotone modal logic. It turns out that there is no adequate uniform construction for M, whence the automata-theoretic approach towards bisimulation invariance does not apply directly. This problem can be overcome if we consider global bisimulations between neighborhood models: one of our main results provides a characterization of the monotone modal mu-calculus extended with the global modalities, as the fragment of monadic second order logic for the monotone neighborhood functor that is invariant for global bisimulations
OPTICAL STARK AND PUMP/PROBE MICROWAVE OPTICAL DOUBLE RESONANCE SPECTROSCOPY OF GAS-PHASE CHROMIUM MONONITRIDE AND VANADIUM MONONITRIDE
No full text Walter J. Balfour, Charles X.W. Qian and Chi Zhou, J. Chem. phys. 106, 4383 (1997); James F. Harrison, J. Phys. Chem. 100, 3513 (1996); Margareta R.A. Blomberg and Per E.M. Siegbahn, Theor. Chim. Acta. 81, 365 (1992).Author Institution: Department of Chemistry and Biochemistry, Arizona State UniversityHigh resolution optical spectroscopic studies of gas-phase chromium mononitride, CrN, and vanadium mononitride, VN, using molecular beam techniques have been performed. The branch feature of the band system for was recorded as a function of the static electric field in the range kV/cm. The resultant Stark shifts were analyzed to produce permanent electric dipole moments of 2.31(4)D and 5.41(2)D for the ground and excited states, respectively. The feature of the band system for was also recorded as a function of static electric field in the range .4 - 1.2 kV/cm. The permanent electric dipole moments derived from a least squares analysis of the Stark shifts were 3.07(1)D for the ground state and 6.15(3)D for the excited state. The hyperfine structure was determined from the analysis of 12 components of the lowest pure rotational levels using the pump/probe microwave-optical double resonance technique. The resulting parameters are (in and . Comparisons to other experimental work and theoretical bonding models are . Observed trends amongst the early transition metals will be discussed
A high pressure x-ray photoelectron spectroscopy experimental method for characterization of solid-liquid interfaces demonstrated with a Li-ion battery system
No full textWe report a methodology for a direct investigation of the solid/liquid interface using high pressure x-ray photoelectron spectroscopy (HPXPS). The technique was demonstrated with an electrochemical system represented by a Li-ion battery using a silicon electrode and a liquid electrolyte of LiClO4 in propylene carbonate (PC) cycled versus metallic lithium. For the first time the presence of a liquid electrolyte was realized using a transfer procedure where the sample was introduced into a 2 mbar N-2 environment in the analysis chamber without an intermediate ultrahigh vacuum (UHV) step in the load lock. The procedure was characterized in detail concerning lateral drop gradients as well as stability of measurement conditions over time. The X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the solid substrate and the liquid electrolyte can be observed simultaneously. The results show that the solid electrolyte interphase (SEI) composition for the wet electrode is stable within the probing time and generally agrees well with traditional UHV studies. Since the methodology can easily be adjusted to various high pressure photoelectron spectroscopy systems, extending the approach towards operando solid/liquid interface studies using liquid electrolytes seems now feasible. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License
