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1.
Summary The mixed ligand complex, [Fe(Phen)2(N3)2] can be extracted into nitrobenzene giving a molar absorptivity of 16750 at 510 nm. This is the basis of a photometric method for iron which may be either in the trivalent or bivalent state. The new method is free from interference from a number of substances and is more sensitive than the ferroin method.
Zusammenfassung Der Eisen-Phenanthrolin-Azid-Mischkomplex [Fe(Phen)2(N3)2] ist mit Nitrobenzol extrahierbar und gibt bei 510 nm eine molare Absorption von 16750. Darauf läßt sich eine photometrische Bestimmungsmethode für zweioder dreiwertiges Eisen begründen. Diese wird von vielen Stoffen nicht gestört und ist empfindlicher als die Ferroinmethode.相似文献
2.
Infrared reflection absorption spectroscopy that used buried metal layer substrates (BML-IRRAS) and density functional cluster calculations were employed to investigate the water related oxidation reactions of 2H + H2O/Si(1 0 0)-(2 × 1), 2D + H2O/Si(1 0 0)-(2 × 1), and H2O + H/Si(1 0 0)-(2 × 1). In addition to the oxygen inserted coupled monohydrides, which were previously reported in the former reaction system, we report several other oxidized Si hydride species in our BML-IRRAS experiments. Three new pairs of vibrational bands are identified between 900 and 1000 cm−1. These vibrational frequencies were calculated using Si9 and Si10 cluster models that included all possible structures from zero to five oxygen insertions into the top layer silicon atoms using a B3LYP gradient corrected density functional method with a polarized 6-31G** basis set for all atoms. The three pairs of vibrational modes are assigned to the scissoring modes of adjacent and isolated SiH2 with zero, one, and two oxygen atoms inserted into the Si back bonds. All the other newly observed vibrational peaks related to Si oxidation are also assigned in this study. The Si-O stretching bands observed in the reaction 2D + H2O/Si(1 0 0)-(2 × 1) show an isotope effect, which suggests that in the system 2H + H2O/Si(1 0 0)-(2 × 1) also, hydrogen atom tunneling plays an important role for the insertion of oxygen atoms into Si back bonds that form oxidized adjacent dihydrides. 相似文献
3.
R. A. Ranga Prabodanie John F. Raffensperger E. Grant Read Mark W. Milke 《Annals of Operations Research》2014,220(1):87-109
Nitrate discharges from diffuse agricultural sources significantly contribute to groundwater and surface water pollution. Tradable permit programs have been proposed as a means of controlling nitrate emissions efficiently, but trading is complicated by the dispersed and delayed effects of the diffuse pollution. Hence, markets in nitrate discharge permits should be carefully designed to account for the underlying spatial and temporal interactions. Nitrate permit markets can be designed similar to the modern electricity markets which use LPs to find the equilibrium prices because the two trading problems have close analogy. In this paper, we propose alternative LP models to find efficient permit prices for year-ahead markets. The model structure varies depending on the catchment hydro-geology and long-term goals of the community. We show how the market price structures are driven by the constraint structure under different environmental conditions. We discuss the physical and economic conditions required to assure consistent prices, the modeling of essential and optional constraints in an LP, and the problem of balancing resource allocation over time among delayed-response discharge units. We then extend the LP model to balance resource allocation over time and to improve the market performance. 相似文献
4.
We improve upon the method of Zhu and Zhu [A method for directly finding the denominator values of rational interpolants, J. Comput. Appl. Math. 148 (2002) 341–348] for finding the denominator values of rational interpolants, reducing considerably the number of arithmetical operations required for their computation. In a second stage, we determine the points (if existent) which can be discarded from the rational interpolation problem. Furthermore, when the interpolant has a linear denominator, we obtain a formula for the barycentric weights which is simpler than the one found by Berrut and Mittelmann [Matrices for the direct determination of the barycentric weights of rational interpolation, J. Comput. Appl. Math. 78 (1997) 355–370]. Subsequently, we give a necessary and sufficient condition for the rational interpolant to have a pole. 相似文献
5.
A. Sri Ranga 《Numerische Mathematik》1994,68(2):283-294
Summary.
We consider certain quadrature rules of highest algebraic
degree of precision that involve strong Stieltjes distributions (i.e.,
strong distributions on the positive real axis). The behavior of the
parameters of these quadrature rules, when the distributions are strong
-inversive Stieltjes distributions, is given. A
quadrature rule
whose parameters have explicit expressions for their determination is
presented. An application of this quadrature rule for the evaluation of a
certain type of integrals is also given.
Received April 17, 1991 / Revised version received July 16, 1993 相似文献
6.
The Role of Substituent Effects in Tuning Metallophilic Interactions and Emission Energy of Bis‐4‐(2‐pyridyl)‐1,2,3‐triazolatoplatinum(II) Complexes
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M. R. Ranga Prabhath Dr. Julia Romanova Prof. Richard J. Curry Prof. S. Ravi P. Silva Dr. Peter D. Jarowski 《Angewandte Chemie (International ed. in English)》2015,54(27):7949-7953
The photoluminescence spectra of a series of 5‐substituted pyridyl‐1,2,3‐triazolato PtII homoleptic complexes show weak emission tunability (ranging from λ=397–408 nm) in dilute (10?6 M ) ethanolic solutions at the monomer level and strong tunability in concentrated solutions (10?4 M ) and thin films (ranging from λ=487–625 nm) from dimeric excited states (excimers). The results of density functional calculations (PBE0) attribute this “turn‐on” sensitivity and intensity in the excimer to strong Pt–Pt metallophilic interactions and a change in the excited‐state character from singlet metal‐to‐ligand charge transfer (1MLCT) to singlet metal‐metal‐to‐ligand charge transfer (1MMLCT) emissions in agreement with lifetime measurements. 相似文献
7.
Nonsteroidal Anti‐inflammatory Drug‐based N‐Allylidene Benzohydrazides and 1‐Acyl‐2‐pyrazolines: Their Synthesis as Potential Cytotoxic Agents In Vitro
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Kavitha Kankanala V. Ranga Reddy Yumnam Priyadarshini Devi Lakshmi Narasu Mangamoori D. Rambabu K. Mukkanti Sarbani Pal 《Journal of heterocyclic chemistry》2015,52(1):105-113
A series of 1‐acyl‐2‐pyrazoline derivatives derived from nonsteroidal anti‐inflammatory drugs was designed as potential anticancer agents. Synthesis of these compounds was carried out via the condensation reaction of chalcones and acid hydrazides under heating. The methodology did not require the use of any costly reagents or catalysts, and the acid hydrazide reactants were readily prepared from mefenamic acid or ibuprofen. A variety of 1‐acyl‐2‐pyrazolines was prepared in good to excellent yields. An N‐allylidene benzohydrazide intermediate was isolated during the reaction optimization study, the structure of which was confirmed unambiguously by X‐ray single crystal data. A range of N‐allylidene benzohydrazides were also prepared in good yields. Some of the compounds synthesized showed promising cytotoxic activities when tested against HCT‐15 human colon cancer cell line in vitro. 相似文献
8.
9.
We consider the sequence of polynomials {Q n } satisfying the L-orthogonality ?[z ?n+m Q n (z)]=0, 0??m??n?1, with respect to a linear functional ? for which the moments ?[t n ]=?? n are all complex. Under certain restriction on the moment functional these polynomials also satisfy a three term recurrence relation. We consider three special classes of such moment functionals and characterize them in terms of the coefficients of the associated three term recurrence relations. Relations between the polynomials {Q n } associated with two of these special classes of moment functionals are also given. Examples are provided to justify this characterization. 相似文献
10.
J. Ashok Kumar Ashok K. Tiwari A.Zehra Ali R. Ranga Rao B. China Raju 《Journal of heterocyclic chemistry》2011,48(6):1251-1257
Series of phosphorylated coumarin derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were synthesized by Pechmann condensation, phosphorylation, and debenzylation reactions in very good yields. Thus, synthesized compounds ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were evaluated for their α‐glucosidase and 1,1‐diphenyl‐2‐picrylhydrazyl scavenging activities; few compounds showed moderate to good activity. J. Heterocyclic Chem., 00 , 00 (2011). 相似文献