Weil-Petersson volumes and intersection theory on the moduli space of curves

In this paper, we establish a relationship between the Weil- Petersson volume of the moduli space of hyperbolic Riemann surfaces with geodesic boundary components of lengths , and the intersection numbers of tautological classes on the moduli space of stable curves. As a result, by using the recursive formula for obtained in the author's Simple geodesics and Weil-Petersson volumes of moduli spaces of bordered Riemann surfaces, preprint, 2003, we derive a new proof of the Virasoro constraints for a point. This result is equivalent to the Witten-Kontsevich formula.

     

The copolymer coating effect on the catalytic activity of magnetic carbon nanotube (CNT-Fe3O4) in the multi-component reactions

Research on Chemical Intermediates - Two new magnetic nanocomposites containing aniline–pyrrole copolymer-coated magnetic carbon nano-tubes (poly(Ani-co-Py)@CNT-Fe3O4) were synthesized and...     

A First-Principles Study of CO2 Hydrogenation on a Niobium-Terminated NbC (111) Surface

As promising materials for the reduction of greenhouse gases, transition-metal carbides, which are highly active in the hydrogenation of CO₂, are mainly considered. In this regard, the reaction mechanism of CO₂ hydrogenation to useful products on the Nb-terminated NbC (111) surface is investigated by applying density functional theory calculations. The computational results display that the formation of CH₄, CH₃OH, and CO are more favored than other compounds, where CH₄ is the dominant product. In addition, the findings from reaction energies reveal that the preferred mechanism for CO₂ hydrogenation is thorough HCOOH^*, where the largest exothermic reaction energy releases during the HCOOH^* dissociation reaction (2.004 eV). The preferred mechanism of CO₂ hydrogenation towards CH₄ production is CO₂^*→t,c-COOH^*→HCOOH^*→HCO^*→CH₂O^*→CH₂OH^*→CH₂^*→CH₃^*→CH₄^*, where CO₂^*→t,c-COOH^*→HCOOH^*→HCO^*→CH₂O^*→CH₂OH^*→CH₃OH^* and CO₂^*→t,c-COOH^*→CO^* are also found as the favored mechanisms for CH₃OH and CO productions thermodynamically, respectively. During the mentioned mechanisms, the hydrogenation of CH₂O^* to CH₂OH^* has the largest endothermic reaction energy of 1.344 eV.     

Synthesis,Characterization, and Crystal Structure of the New Schiff‐Bases derived from 1,2,4‐Triazole and the Structure of [(PPh3)2Cu(AMTT)]NO3·EtOH (AMTT = 4‐Amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione)

The reactions of 4‐amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AMTT, L1 ) with 2‐thiophen carbaldehyde, salicylaldehyde and 2‐nitrobenzaldehyde in methanol led to the corresponding Schiff‐bases ( L1a‐c ). The reaction of L1 with [(PPh₃)₂Cu]NO₃ in ethanol gave the ionic complex [(PPh₃)₂Cu(L1)]NO₃·EtOH ( 2 ) All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for L1a at 20 °C: space group P2₁/n with a = 439.6(2), b = 2074.0(9), c = 1112.8(4) pm, β = 93.51(3)°, Z = 4, R₁ = 0.0406, L1b at ?80 °C: space group P2₁/n with a = 1268.9(2), b = 739.3(1), c = 1272.5(1) pm, β = 117.97(1)°, Z = 4, R₁ = 0.0361, L1c at ?80 °C: space group P2₁/n with a = 847.8(1), b = 1502.9(2), c = 981.5(2) pm, β = 110.34(1)°, Z = 4, R₁ = 0.0376 and for 2 at ?80 °C: space group with a = 1247.8(1), b = 1270.3(1), c = 1387.5(1) pm, α = 84.32(1)°, β = 84.71(1)°, γ = 63.12(1)°, Z = 2, R₁ = 0.0539.     

Structural characterization of a copper(II) complex containing oxidative cyclization of N-2-(4-picolyl)-N′-(4-methoxyphenyl)thiourea,new ligands of 4-picolylthiourea derivatives and the precursor molecular structure of oxidative cyclization of N-(2-pyridyl)-N′-(4-methoxyphenyl)thiourea

Three new compounds of aryl thiourea derivatives, namely N-2-(4-picolyl)-N′-(4-methoxyphenyl)thiourea (L1), N-2-(6-picolyl)-N′-(4-methoxyphenyl)thiourea (L2) and N-2-(4-picolyl)-N′-(4-nitrophenyl)thiourea (L3), and the new copper(II) complex [Cu(4PicTz4OMePh)(OAC)(EtOH)] (C1), as a result of oxidative cyclization of the ligand (L1), were synthesized. In addition, pure precursor (P1), as the product of the oxidative cyclization of N-(2-pyridyl)-N′-(4-methoxyphenyl)thiourea (L4), was isolated and characterized. Ligands (L1) and (L2) were characterized by ¹H and ¹³C NMR and single crystal X-ray analysis. ¹H NMR spectroscopy showed strong hydrogen bonding interactions between N′H-functionalities and the pyridine nitrogen atoms as well as weak intermolecular hydrogen bonding between the thione sulfur and the NH hydrogen. Structural studies of complex (C1) showed that the copper ion is five-coordinated with a square-pyramidal environment. The oxidative cyclization of ligand (L1) results in an anionic bidentate ligand in complex (C1). Both ligand (L1) and precursor (P1) crystallize as centrosymmetric dimers.     

The anhydride route to Group 15/16 ligands in oligomeric and polymeric environments: from metal complexes to supraionic chemistry

The aim of this paper is to introduce a synthetic concept suitable for the preparation of a broad variety of compounds. The so-called anhydride route (in this article the term anhydride is used for compounds derived from corresponding acids by formal loss of H2O, H2S and H2Se) has so far led to a range of unusual Group 15/16 ligands in oligomeric and polymeric environments. Commonly, reactions of neutral precursor molecules, for example, [{RP(S)(mu-S)}2] (R=4-anisyl) Lawesson's reagent or [{PhP(Se)(mu-Se)}2] Woollins's reagent and metal salts are performed to result in novel coordination compounds in which ligands and metal atoms form coordination oligomers and polymers. An attempt is made to relate the outcome of the investigations to the type of metal used. By relating the strength of ionic interactions, which correspond to metal-donor distances, to phenomena observed in the solid-state structures, an aspect of supraionic chemistry is described. Chemistry of and beyond novel Group 15/16 anions is further discussed using a novel approach in coordination chemistry where the chemical nature of ligands is unknown prior to the experiment despite the use of a range of similar starting materials.     

A recipe for new organometallic polymers and oligomers? Synthesis and structure of an oligo- and a polymeric arrangement of P-S anions

A route to organometallic polymers and oligomers is described using metal complexes with P/S-ligands as examples.     

A PLS-based extractive spectrophotometric method for simultaneous determination of carbamazepine and carbamazepine-10,11-epoxide in plasma and comparison with HPLC

Carbamazepine (CBZ) undergoes enzyme biotransformation through epoxidation with the formation of its metabolite, carbamazepine-10,11-epoxide (CBZE). A simple chemometrics-assisted spectrophotometric method has been proposed for simultaneous determination of CBZ and CBZE in plasma. A liquid extraction procedure was operated to separate the analytes from plasma, and the UV absorbance spectra of the resultant solutions were subjected to partial least squares (PLS) regression. The optimum number of PLS latent variables was selected according to the PRESS values of leave-one-out cross-validation. A HPLC method was also employed for comparison. The respective mean recoveries for analysis of CBZ and CBZE in synthetic mixtures were 102.57 (+/-0.25)% and 103.00 (+/-0.09)% for PLS and 99.40 (+/-0.15)% and 102.20 (+/-0.02)%. The concentrations of CBZ and CBZE were also determined in five patients using the PLS and HPLC methods. The results showed that the data obtained by PLS were comparable with those obtained by HPLC method.     

Nanoparticle Tracking Analysis: Enhanced Detection of Transparent Materials

This study proposes a novel and simple in-house design of a nanoparticle tracking analysis (NTA) device for the online characterization of nanoparticles in an aqueous solution. The particle size distribution of two sets of model nanoparticles, for example, transparent (SiO₂) and opaque (TiO₂) materials with respect to water as a dispersion medium could be successfully analyzed. Experiments are conducted using two different laser wavelengths of 632.8 (red) and 510 nm (green) and a range of concentrations. The accuracy of the green laser is larger compared to the red laser for all particle concentrations used. The measured average diameter using the presented in-house NTA setup is in the acceptable range compared to the electron microscopy data. The average diameter of the transparent (SiO₂) and opaque (TiO₂) samples is calculated as 36.29 and 27.26 nm using NTA, 36.44 and 27.8 nm analyzing field emission scanning electron microscopy images, and 23.97 and 19.7 nm analyzing transmission electron microscopy images. In the new viewing sample holder, nanoparticles undergo mere Brownian motion with no bulk drift velocity. The effect of solid concentration and wavelength of the laser light on the performance of the NTA sensor is investigated, and the optimal concentration range for model particles is reported.