A pH‐responsive cyclopolymer having phospho‐ and sulfopropyl pendents in the same repeating unit: Synthesis,characterization, and its application as an antiscalant

A new zwitterionic monomer 3‐[diallyl{3‐(diethoxyphosphoryl)propyl}ammonio]propane‐1‐sulfonate has been synthesized and cyclopolymerized to give the corresponding polyzwitterion (±) (PZ) bearing both phosphonate and sulfonate functionalities on each repeating unit. phosphonate ester hydrolysis in PZ gave a pH‐responsive dibasic polyzwitterionic acid (±) (PZA) bearing ? PO₃H₂ units. The PZA under pH‐induced transformation was converted into polyzwitterion/anion (± ?) (PZAN) and polyzwitterion/dianion (± =) (PZDAN) having respective ? PO₃H^? and ? PO₃^2? units. The polymers′ interesting solubility and viscosity behaviors have been investigated in detail. The apparent protonation constants in salt‐free water and 0.1 M NaCl of the ? PO₃^2? in (± =) (PZDAN) and ? PO₃H^– in (± ?) (PZAN) as well as in their corresponding monomeric units have been determined. Evaluation of antiscaling properties of the PZA using supersaturated solution of CaSO₄ revealed ≈100% scale inhibition efficiency at a meager concentration of 20 ppm for a duration of 45 h at 40 °C. The PZA has the potential to be used effectively as an antiscalant in reverse osmosis plant. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5130–5142     

Solvent- and metal-free selective oxidation of thiols to disulfides using I2/DMSO catalytic system

We describe herein a simple, fast and inexpensive protocol for the oxidative coupling of thiols employing a stoichiometric amount of DMSO and iodine as the catalyst. Various aromatic disulfides were obtained in good to excellent yields in short reaction times at room temperature, while aliphatic disulfides were achieved in good yields when the reactions were conducted under microwave irradiation.     

Structure Characterization and Lead Detoxification Effect of Carboxymethylated Melanin Derived from <Emphasis Type="Italic">Lachnum</Emphasis> Sp.

In the present study, an intracellular melanin, named LIM205, was separated from Lachnum YM205 mycelia and was purified on a Sephadex G-15 column. The molecular weight of LIM205 was determined as 522 Da, and its molecular formula was speculated as C₂₈H₁₄N₂O₇S. The possible chemical structure of LIM205 was determined according to the results of Fourier transform infrared (FT-IR), ¹H NMR, ¹³C NMR, and pyrolysis/GC-MS analysis. With the aim to increase its water solubility, its carboxymethylated derivative, named CLIM205, was formed by the substitution of hydrogen atoms in LIM205 with one, two, and three carboxymethylate groups. FT-IR, UV, and ESI-MS analysis demonstrated that the carboxymethylate groups were conjugated onto LIM205. The lead detoxification activities of LIM205 and CLIM205 had also been investigated. In vivo test showed that both LIM205 and CLIM205 reduced the tissue lead concentration, enhanced lead excretion, and reversed lead-induced alterations in superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) concentrations in mice, with CLIM205 showed better efficacy. The study indicates that LIM205 and CLIM205 have significant lead detoxification effect which will contribute to solve related problems.     

Separation and identification of a new saponin from the flowers of Guaiacum officinale L

A triterpenoid saponin, guaianin O (1), oleanolic acid 3-O-{α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 3)]-α-L-arabinopyranoside}-28- O-[β-D-glucopyranosyl]-ester, was isolated from the n-butanol extract of flowers of Guaiacum officinale L. The structural elucidation of 1 was accomplished by extensive studies of both one and two dimensional 1H, 13C-NMR spectra, the FAB mass spectrum, and alkaline and acid hydrolyses.     

Synthesis of zinc trisubstituted hydrazido complexes and ortho-metalation of 4-(dimethylamino)pyridine

The zinc hydrazide complexes [EtZn(N(SiMe(3))NMe(2))](2), [EtZn(N(Me)NMe(2))](4), and Zn(3)Et(4)(N(Et)NMe(2))(2) were synthesized by allowing excess hydrazine, HN(R)NMe(2), to react with diethyl zinc. The product of the reaction between ZnEt(2) and HN(i-Pr)NMe(2)ortho-metalated 4-(dimethylamino)pyridine (DMAP) at room temperature, producing the complex Zn[(NC(5)H(3)-p-NMe(2))ZnEt(N(i-Pr)NMe(2))](2). At elevated temperatures, Zn(3)Et(4)(N(Et)NMe(2))(2) also ortho-metalated DMAP, but [EtZn(N(Me)NMe(2))](4) did not. Single-crystal X-ray diffraction studies revealed that the hydrazide ligands in [EtZn(N(SiMe(3))NMe(2))](2) act as bridging mono-hapto amide ligands, and in Zn(3)Et(4)(N(Et)NMe(2))(2) and Zn[(NC(5)H(3)-p-NMe(2))ZnEt(N(i-Pr)NMe(2))](2) the hydrazide ligands are di-hapto.     

Analysis of two stacked cylindrical dielectric resonators in a TE₁₀₂ microwave cavity for magnetic resonance spectroscopy

The frequency, field distributions and filling factors of a DR/TE??? probe, consisting of two cylindrical dielectric resonators (DR1 and DR2) in a rectangular TE??? cavity, are simulated and analyzed by finite element methods. The TE(+++) mode formed by the in-phase coupling of the TE??(δ)(DR1), TE??(δ)(DR2) and TE??? basic modes, is the most appropriate mode for X-band EPR experiments. The corresponding simulated B(+++) fields of the TE(+++) mode have significant amplitudes at DR1, DR2 and the cavity's iris resulting in efficient coupling between the DR/TE??? probe and the microwave bridge. At the experimental configuration, B(+++) in the vicinity of DR2 is much larger than that around DR1 indicating that DR1 mainly acts as a frequency tuner. In contrast to a simple microwave shield, the resonant cavity is an essential component of the probe that affects its frequency. The two dielectric resonators are always coupled and this is enhanced by the cavity. When DR1 and DR2 are close to the cavity walls, the TE(+++) frequency and B(+++) distribution are very similar to that of the empty TE??? cavity. When all the experimental details are taken into account, the agreement between the experimental and simulated TE(+++) frequencies is excellent. This confirms that the resonating mode of the spectrometer's DR/TE??? probe is the TE(+++) mode. Additional proof is obtained from B?(x), which is the calculated maximum x component of B(+++). It is predominantly due to DR2 and is approximately 4.4 G. The B?(x) maximum value of the DR/TE??? probe is found to be slightly larger than that for a single resonator in a cavity because DR1 further concentrates the cavity's magnetic field along its x axis. Even though DR1 slightly enhances the performance of the DR/TE??? probe its main benefit is to act as a frequency tuner. A waveguide iris can be used to over-couple the DR/TE??? probe and lower its Q to ≈150. Under these conditions, the probe has a short dead time and a large bandwidth. The DR/TE??? probe's calculated conversion factor is approximately three times that of a regular cavity making it a good candidate for pulsed EPR experiments.     

Wave-function-based characteristics of hybrid mesons

We propose some extensions of the quark potential model to hybrids, fit them to the lattice data and use them for the purpose of calculating the masses, root mean square radii and wave functions at the origin of the conventional and hybrid charmonium mesons. We treat the ground and excited gluonic field between a quark and an antiquark as in the Born-Oppenheimer expansion, and use the shooting method to numerically solve the required Schrödinger equation for the radial wave functions; from these wave functions we calculate the mesonic properties. For masses we also check through a Crank Nichelson discretization. For hybrid charmonium mesons, we consider the exotic quantum number states with J ^PC = 0^+?, 1^?+ and 2^+?. We also compare our results with the experimentally observed masses and theoretically predicted results of the other models. Our results have implications for scalar form factors, energy shifts, magnetic polarizabilities, decay constants, decay widths and differential cross-sections of conventional and hybrid mesons.     

On the Constant Metric Dimension of Generalized Petersen Graphs P（n, 4）

In this paper,we consider the family of generalized Petersen graphs P(n,4).We prove that the metric dimension of P(n,4) is 3 when n ≡ 0(mod 4),and is 4 when n = 4k + 3(k is even).For n ≡ 1,2(mod 4) and n = 4k + 3(k is odd),we prove that the metric dimension of P(n,4) is bounded above by 4.This shows that each graph of the family of generalized Petersen graphs P(n,4)has constant metric dimension.