1,807 research outputs found
Solventless VOC chemisorption by silver metallocycles
No full textSolventless VOC chemisorption by silver metallocycles
Oumarou C. S.a, Tekarli S.,b Nesterov V.,b Omary M. A.,b Burini A.,a Galassi R.,a
aSchool of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino; e-mail: [email protected]
b Department of Chemistry, University of North Texas, Denton, TX 76203, USA
Prior work has focused on detection/sensing aspects of VOCs,[1] this work proposes a method for their simultaneous filtration and removal through their strong chemisorption to a silver(I) metallocyclic trimer.[2] A solid cyclotrimer can quantitatively remove entire molar integers of VOCs (1-3 equivalents of VOCs per mole of the nitrated trimer) from the vapor phase in a solventless “green” chemical process, which is unprecedented for this class of cyclic d10 complexes.
Figure 1. Illustration of quadrupole-dipole interactions involving the [Ag(μ-Pz-2CF3)]3 or [Ag(3,5-(NO2)2pz)]3 trimers and acetonitrile using M06/CEP-31G(d). MEP surfaces are plotted in two manners, either mapped on electron density surfaces (rainbow plots with the color scale shown; isodensity = 0.0004) or positive (blue) and negative (red) regions in space (range = ± 2.2 a. u.; isodensity = 0.02)
[1] Yaghi et al., PNAS 2008, 105, 11623
[2] R. Galassi, S. Ricci, A. Burini, A. Macchioni, L. Rocchigiani, F. Marmottini, S. Tekarli, V. Nesterov, M. A. Omary, J. Am. Chem. Soc., 2013, submitted
Supramolecular Chemistry and photophysical Properties of a New Gold (I) Cyclic Trinuclear Complex, [Au(μ-C2,N3-1-vinylimidazole)]3
Get PDFSupramolecular Chemistry and photophysical Properties of a New Gold (I) Cyclic Trinuclear Complex, [Au(μ-C2,N3-1-vinylimidazole)]3
R. Galassia, A. Burinia, C. S. Oumaroua, V. N. Nesterov b, M. A. Omary b.
a Dipartimento di Scienze Chimica, Università di Camerino, Via Sant Agostino, 1, 62032 Camerino, Italia
b Department of Chemistry, University of North Texas, Denton, TX 76203, USA
email: [email protected]
In the past years several cyclic trinuclear complexes (CTC’s) have been synthetized and characterized on the basis of the capacity of d10 transition metal ions to give bicoordinated linear compounds. This intriguing class of compounds display pi-acid/ pi-base properties that can be finely tuned by: the nature of the metal, the substituents on the ligand or the ligand itself. [1] These complexes are attractive building blocks to obtain supramolecular compounds showing interesting photopysical properties [2] or heterobimetallic cyclic trinuclear complexes with potential use in mixed-metal catalysis [3]. Here we report the synthesis of a novel gold (I) CTC, [Au(μ-C2,N3-1-vinylimidazole)]3, and the study of some photophysical properties of its supramolecular derivatives obtained by the intercalation of metal ions in between the metallocycles.
[1] S.M. Terkali, T.R. Cundari, M.A. Omary, J. Am. Chem. Soc. 2008, 130, 1669
[2] a) A. Burini, R. Bravi, J. P. Fackler Jr, Galassi R., T. A. Grant, M. A. Omary, B. R. Pietroni, R. J. Staples . Inorg. Chem. 2000, 39; 3158.b) Burini A, Fackler J. P, JR, Galassi R., Grant T. A, Omary M. A, Rawashdeh-Omary M. A, Pietroni B. R, Staples R.J. J. Am. Chem. Soc. 2000, 122; 11264.
[3] A. Mohamed, R. Galassi, F. Papa, A. Burini, J.P. Fackler , Jr. Inorg. Chem. 2006, 45, 7770-7776
[5] R. Galassi, S. Ricci, A. Burini, A. Macchioni, L. Rocchiagiani, F. Marmottini, S.M. Terkali, V.N. Nesterov, M.A. Omary, Inorg. Chem. 2013, 52, 14124-1413
Coinage metals trinuclear metallocycles: old and new aspects of this class of compounds
Get PDFCoinage metals trinuclear metallocycles: old and new aspects of this class of compounds
Galassi R. a, Oumarou C. S. a, Omary A. M. b, Nesterov V. b, Burini A.a
aSchool of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino; e-mail: [email protected]
b Department of Chemistry, University of North Texas, Denton, 1155 Union Circle, TX 76203, USA; e-mail: [email protected]
Azoles such as imidazoles and pyrazoles are optimal bridging ligands to obtain C,N or N,N trinuclear coinage metals metallocycles. Since past decade till now, few worldwide research groups including us have focused their attention to their synthesis and characterization.[1] Moreover, the photophysical properties[2] the extended network of metallophilic bondings in the supramolecular structure and the pi-acid/pi-base chemistry[3] of these compounds directed the research to theoretical studies bringing to a better interpretation of the experimental behaviors.[4] Here we report the synthesis of new coinage metals metallocycles and their spectroscopic characterizations highlighting points of continuity with the previous analogs and new features for new perspective research lines. As in example, the 1-vinylimidazole resembles the acid-base chemistry of the 1-benzylimidazole gold(I) metallocycle, while substitution in position 4,5 of 1-benzylimidazole with electron-withdrawing group, do not allow the formation of metallocycles with the same synthethic route and mononuclear gold(I) derivatives have been obtained. The nature of the heterocycle and of the substituents, in addition to their position in the azolate ligand defines and tunes the properties of the final products.
References:
1) Galassi, R.; Burini, A.; Omary-Rawanashed, M., Omary, M. A., Comm. Inorg. Chem. 2014, in submission.
2) Rawashdeh-Omary, M. A.; Omary, M. A.; Fackler Jr, J. P, Galassi R., Pietroni, B. R.; Burini, A. J. Am. Chem. Soc 2001, 123; 9689-9691.
3) Burini, A.;. Fackler Jr, J. P; Galassi R., Grant, T. A.. Omary, M. A; Rawashdeh-Omary, M. A.; Pietroni, B. R.; Staples R. J. J. Am. Chem. Soc., 2000; 11264-11265.
4) Galassi, R.; Ricci, S.; Burini, A.; Macchioni, A; Marmottini, F.; Tekarli, S. M.; Nesterov, N.V.; Omary, M. A. Inorg. Chem. 2013, 52, 14124-14137
Harpactus vedicus NESTEROV 1994
No full text<i>Harpactus vedicus</i> Nesterov, 1994, stat. resurr. <p>Figs 1, 3–5</p> <p> <i>Harpactus vedicus</i> Nesterov, 1994: 35, ♀, ♂ (holotype: ♀, Armenia, Khozrov Nature Reserve, Vedic section, 1300 m, 6. VI.1982, M. Nesterov leg. [I.I. Schmalhausen Institute of Zoology of National Academy of Sciences of Ukraine, Kiev]), not examined. Synonymized with <i>Harpactus elegans</i> (Lepeletier de Saint Fargeau, 1832) by Nemkov, 1997: 19.</p> <p> <i>Harpactus transcaucasicus</i> Nemkov, 1994: 69, ♀, ♂ (holotype, ♀: Azerbaijan, Nakhichevan ASSR, 35 km north of Nakhichevan, 20. VI.1985, V. Tobias leg. [ZISP]), examined. <b>Syn. n.</b>; Nemkov, 1996: 1208; Yildirim <i>et al</i>., 2016: 16; Mokrousov <i>et al</i>., 2019: 12; Kaplan & Yildirim 2021: 35; 2023: 1681.</p> <p> MATERIAL EXAMINED. <i>Type material</i>: <b>Azerbaijan</b>: <i>Nakhchivan Autonomous Republic</i>: 35 km north of Nakhichevan, 20. VI 1985, 2 ♀, 12 ♂, V. Tobias (holotype and paratypes of <i>Harpactus transcaucasicus</i> Nemkov, 1994). <i>Other material</i>: <b>Azerbaijan</b>, <i>Nakhchivan Autonomous Republic</i>: Babek, 3 km NE Sirab, 39°18'N 45°32'E, 1250 m, 12. VI 2019, 1 ♀; Babek, Goynuk, 39°18'N 45°40'E, 1680 m, 12. VI 2019, 13 ♀, 15 ♂; Shakhbuz, Zarnatun, 39°31'N 45°46'E, 1550 m, 14, 18. VI 2019, 4 ♀, 33 ♂; Julfa, Gazanchi, 39°13'N 45°41'E, 1300 m, 15. VI 2019, 2 ♂; Julfa, Milakh, 39°15'N 45°43'E, 1430 m, 15. VI 2019, 1 ♀, 1 ♂; Julfa, Teyvaz, 39°15'N 45°46'E, 1645 m, 15. VI 2019, 2 ♀, 1 ♂; Ordubad, Aghdara, 39°06'N 45°54'E, 2000 m, 17. VI 2019, 1 ♂; Shakhbuz, Gomur, 39°27'N 45°44'E, 1790 m, 18. VI 2019, 1 ♀; Shakhbuz, Kechili, 39°22'N 45°43'E, 1800 m, 19. VI 2019, 1 ♀; Shakhbuz, Kulus, 39°21'N 45°37'E, 1395 m, 14, 19, 26. VI 2020, 6 ♀, 4 ♂; 27. VI 2021, 3 ♀; 4.VII 2021, 1 ♀, 1 ♂; Shakhbuz, Kechili, 39°22'N 45°43'E, 1800 m, 12.VII 2022, 6 ♂.</p> <p> NOTE. Paratypes of <i>Harpactus vedicus</i> Nesterov, 1994 – 9 ♀, 90 ♂, Armenia, Khozrov Nature Reserve and 1 ♀, 1 ♂, Azerbaijan, Nakhchivan Autonomous Republic, Bilav could not be found in the ZISP collection, although according to Nesterov (1994: 35) some of them should be kept there.</p> <p>DISTRIBUTION. Armenia, Azerbaijan, Turkey.</p>Published as part of <i>Mokrousov, M. V., Proshchalykin, M. Yu. & Maharramov, M. M., 2024, TO THE TAXONOMY OF HARPACTUS VEDICUS NESTEROV, 1994 (HYMENOPTERA, CRABRONIDAE, BEMBICINAE), pp. 19-24 in Far Eastern Entomologist 499</i> on pages 21-22, DOI: 10.25221/fee.499.2, <a href="http://zenodo.org/record/10928362">http://zenodo.org/record/10928362</a>
Origin of inflation in CFT driven cosmology: R 2 -gravity and non-minimally coupled inflaton models
Get PDFWe present a detailed derivation of the recently suggested new type of hill-top inflation [arXiv:1509.07270] originating from the microcanonical density matrix initial conditions in cosmology driven by conformal field theory (CFT). The cosmological instantons of topology S-1 x S-3, which set up these initial conditions, have the shape of a garland with multiple periodic oscillations of the scale factor of the spatial S-3-section. They describe underbarrier oscillations of the inflaton and scale factor in the vicinity of the inflaton potential maximum, which gives a sufficient amount of inflation required by the known CMB data. We build the approximation of two coupled harmonic oscillators for these garland instantons and show that they can generate inflation consistent with the parameters of the CMB primordial power spectrum in the non-minimal Higgs inflation model and in R-2 gravity. In particular, the instanton solutions provide smallness of inflationary slow-roll parameters is an element of and eta < 0 and their relation is an element of similar to eta(2) characteristic of these two models. We present the mechanism of formation of hill-like inflaton potentials, which is based on logarithmic loop corrections to the asymptotically shift-invariant tree-level potentials of these models in the Einstein frame. We also discuss the role of R-2-gravity as an indispensable finite renormalization tool in the CFT driven cosmology, which guarantees the nondynamical (ghost free) nature of its scale factor and special properties of its cosmological garland-type instantons. Finally, as a solution to the problem of hierarchy between the Planckian scale and the inflation scale we discuss the concept of a hidden sector of conformal higher spin fields
New complexity analysis of a full Nesterov- Todd step infeasible interior-point algorithm for symmetric optimization
Get PDFsummary:A full Nesterov-Todd step infeasible interior-point algorithm is proposed for solving linear programming problems over symmetric cones by using the Euclidean Jordan algebra. Using a new approach, we also provide a search direction and show that the iteration bound coincides with the best known bound for infeasible interior-point methods
Online monitoring of gas&oil pipeline by distributed optical fiber sensors
No full textDistributed optical fiber sensors (OFS) are very promising candidates for remote online-monitoring of pipelines, above or below ground as well as underwater. Usage of OFS is a very interesting way for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high sensing speed, light weight, small size, and flexibility. In particular, phase-sensitive Optical Time Domain Reflectometry (F-OTDR) can provide for sensitive and prompt detection of vibro-acoustic signals. It can be useful for leakage or other malfunctioning detection along the pipeline or also for monitoring of processes in wells. Leakage of hydrocarbon products from a pipeline not only represents loss of natural resources, but it also poses a serious and dangerous environmental pollution, in addition to the risk of fire disaster. Suitable diagnostic systems need to be used to monitor gas and oil pipelines in order to early detect and precisely locate leakage problems. Furthermore, by specific analysis of the backscattered signals, φ-OTDR sensors can detect unwanted activities (intrusion or drilling or others) in proximity of the pipeline. To achieve such detection capability, a single-mode optical fiber is laid along the pipeline and it is continuously interrogated by a narrow-linewidth 1.55 μm laser in order to detect vibrations and acoustic perturbations in proximity of the fiber and pipeline itself. Sensing with φ-OTDR in wells makes it possible to raise the quantity and quality of information from well seismic observations, for monitoring the hydraulic fracturing and extracting of hydrocarbons. Also this technology allows cost reduction of the operations. In this paper, a real-time distributed oil and gas pipeline security pre-warning system based on the φ-OTDR technology is proposed. The experimental platform is established in the laboratory and some trials have been performed in the field over a pipeline length of 180 km in Yakutia (RU) and in well. Both the laboratory and in-field experiments proven the validity of the optical sensing technology applied to pipelines and wells, so we are now proposing these sensors to the Scientific and Industrial communities
Absolute myocardial blood flows derived by dynamic CZT scan vs invasive fractional flow reserve: Correlation and accuracy
No full textPurpose: To define the diagnostic power of absolute myocardial blood flow (MBF) evaluation on dynamic CZT imaging in intermediate risk patients in comparison with invasive coronary angiography (ICA) and fractional flow reserve (FFR). Methods: Twenty-three stable CAD patients underwent one-day dynamic rest-stress 99mTc-Sestamibi myocardial perfusion imaging by CZT camera. Stress and rest MBF values were calculated semi-automatically using a net retention model by Leppo. Coronary flow reserve (CFR) and flow difference (FD) [MBF stress − MBF rest] were also estimated. A total of 28 vessels were functionally quantified with FFR: 19 (68%) vessels with a stenosis ≥ 70% and 9 (32%) with < 70% stenotic lesions. Results: The mean global MBFs at rest and during stress were 0.36 (IQR 0.33-0.54) mL/min/g and 0.67 (IQR 0.55-0.81) mL/min/g, respectively, with an average CFR of 1.80 (IQR 1.35-2.24). Moderate correlations between stenosis severity and FFR (r = 0.45; P =.01), stress MBF (r = −0.46; P =.01) and FD (r = −0.37; P =.04) were detected. FFR abnormalities were best predicted by absolute stress MBF, CFR and FD with values of ≤ 0.54 mL/min/g (sensitivity 61.5%; specificity 93.3%), ≤ 1.48 (sensitivity 69.2%; specificity 93.3%) and ≤ 0.18 mL/min/g (sensitivity 69.2%; specificity 100%), respectively. Conclusions: The values of stress MBF, CFR and FD obtained through dynamic CZT acquisitions compare well with invasive FFR. The clinical use of dynamic acquisition of myocardial perfusion imaging by CZT may help cardiologist in the detection of hemodynamically significant CAD
Computing closest stable nonnegative matrix
No full textThe problem of finding the closest stable matrix for a dynamical system has many applications. It is studied for both continuous and discrete-time systems and the corresponding optimization problems are formulated for various matrix norms. As a rule, nonconvexity of these formulations does not allow finding their global solutions. In this paper, we analyze positive discrete-time systems. They also suffer from nonconvexity of the stability region, and the problem in the Frobenius norm or in the Euclidean norm remains hard for them. However, it turns out that for certain polyhedral norms, the situation is much better. We show that for the distances measured in the max-norm, we can find an exact solution of the corresponding nonconvex projection problems in polynomial time. For the distance measured in the operator `∞-norm or `1-norm, the exact solution is also efficiently found. To this end, we develop a modification of the recently introduced spectral simplex method. On the other hand, for all these three norms, we obtain exact descriptions of the region of stability around a given stable matrix. In the case of the max-norm, this can be seen as an extension onto the class of nonnegative matrices, the Kharitonov theorem, providing a stability criterion for polynomials with interval coefficients [V. L Kharitonov, Differ. Uravn., 14 (1978), pp. 2086-2088; K. Panneerselvam and R. Ayyagari, Internat. J. Control Sci. Engrg., 3 (2013), pp. 81-85]. For practical implementation of our technique, we developed a new method for approximating the maximal eigenvalue of a nonnegative matrix. It combines the local quadratic rate of convergence with polynomial-time global performance guarantees
Influence of the Laser Frequency Drift in Phase-Sensitive Optical Time Domain Reflectometry
No full textAbstract: The influence of the laser frequency drift on the operation of phase-sensitive optical time domain reflectometry (φ-OTDR) systems is considered. Theoretical results based on a new numerical φ-OTDR model demonstrating the influence of the laser frequency instability on a signal are reported. This model is verified based on experimental data. It has been used to calculate the signal-to-noise ratio (SNR) of the system for different parameters of the laser source stability. As a result, quantitative requirements for lasers used in φ-OTDR systems are formulated
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