Kinetics of the mediatory reduction ofgem-dichlorocyclopropanes

The effect of the nature of organic electron transfer agents and of Pt^II, Pd^II, Rh^II, Co^II, Ni^II, Cu^II, Cr^III, Mn^II, Ti^III, V^III, Zn^II, and Ag^I metal ions on the kinetics of the homogeneous reduction ofgem-dichlorocyclopropanes has been studied. Pt^II, Pd^II, Rh^III, Co^II, and Ni^II ions accelerate this process, V^III and Ag^I ions exert practically no effect on the reduction rate, and the rest of the metal ions exhibit inhibitor properties.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1407–1410, August, 1993.     

Multielement (H,C, N,O, S) stable isotope characteristics of lamb meat from different Italian regions

The study focuses on the ²H/H, ¹³C/¹²C, ¹⁵N/¹⁴N, ¹⁸O/¹⁶O and ³⁴S/³²S values of defatted dry matter (DFDM) and on the ²H/H, ¹³C/¹²C and ¹⁸O/¹⁶O values of the fat fraction of meat samples from various lamb types reared in seven Italian regions, following different feeding regimes (forage, concentrate, milk). The ¹³C/¹²C (r = 0.922), ²H/H (r = 0.577) and ¹⁸O/¹⁶O (r = 0.449) values of fat and DFDM are significantly correlated, the fat values being significantly lower for C and H and higher for O than for DFDM values and the differences between the two fractions not being constant for different lamb types. The feeding regime significantly affected the ¹³C/¹²C, ¹⁵N/¹⁴N, ¹⁸O/¹⁶O and ²H/H of fat. The DFDM ²H/H, and ¹⁸O/¹⁶O values, excluding an outlier, are significantly correlated with the corresponding values in meteoric waters, thus allowing us to trace the variability of geoclimatic factors. ¹⁵N/¹⁴N is influenced by pedoclimatic conditions, whereas ³⁴S/³²S is influenced by the sea spray effect and the surface geology of the provenance area. By applying stepwise linear discriminant analysis only the ²H/H of fat was found not to be significant and 97.7% of the samples were correctly assigned to the lamb type and more than 90% cross‐validated. With the feeding regime, 97.7% of the samples were both correctly assigned and cross‐validated using a predictive model including ¹³C/¹²C, ¹⁵N/¹⁴N, ¹⁸O/¹⁶O, ³⁴S/³²S of DFDM and ¹⁸O/¹⁶O of fat. Copyright © 2009 John Wiley & Sons, Ltd.     

The spectrophotometric and titrimetric determination of gold with ferroin as reagent

A spectrophotometric and a photometric titration method in a two-phase system for the determination of gold with ferroin is reported. Both methods are rapid and reproducible with an accuracy of ±1%. In the spectrophotometric determination Co²⁺, Cu²⁺, Ni²⁺ , Fe³⁺, Zn²⁺, Mn²⁺ and Cr³⁺ do not interfere with the determination of gold and Pt⁴⁺, Pd²⁺, Hg²⁺, Ir⁴⁺ and Os⁴⁺ can be tolerated up to a ratio of 1:1. The titrations can also be carried out in the presence of a number of diverse ions, e.g. Ni²⁺, Cu²⁺, Co²⁺, Fe³⁺, Zn²⁺, Cr³⁺, Mn²⁺, without interference; the platinum metals and Hg²⁺ cause interference but, by the use of the spectrophotometric procedure, this can be reduced.     

Production of charge-induced X-rays during PIXE studies using light and heavy ion-beams

A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of¹H⁺,¹H₂ ⁺,²H⁺,²H₂ ⁺,³He⁺,³He²⁺,⁴He⁺,¹⁴N⁺,¹⁴N²⁺,¹⁶O⁺ and²⁰Ne⁺ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.     

Zero-Field Splittings and Redox Potentials in an Isostructural Series of Dinuclear FeIITiIV,FeIIITiIV, and MnIITiIV Complexes with a Face-Sharing Bridging Motive

The ligand H₆ioan has been used to synthesize the three dinuclear complexes [(ioan)Mn^IITi^IV], [(ioan)Fe^IITi^IV], and [(ioan)Fe^IIITi^IV]⁺. The face-sharing bridging mode of the three phenolates provides short M-Ti^IV distances of ≈3.0 Å. Mössbauer spectra of [(ioan)Fe^IIITi^IV]⁺ show a magnetically split six-line spectrum at 3 K in zero magnetic field demonstrating a slow magnetic relaxation. Magnetic measurements provide a zero-field splitting of |D|=5 cm⁻¹ in [(ioan)Fe^IITi^IV]. EPR spectroscopy demonstrates sizable zero-field splittings of the S=5/2 spin systems of [(ioan)Mn^IITi^IV] (D=0.246 cm⁻¹) and [(ioan)Fe^IIITi^IV]⁺ (D<−1 cm⁻¹) that can be related to enforced covalency of the M-O^ph bonds. [(ioan)Fe^IIITi^IV]⁺ exhibits a reversible reduction at −0.26 V vs. Fc⁺/Fc demonstrating the facile accessibility of Fe^III and Fe^II. In contrast to an irreversible oxidation in [(ioan)Ni^IITi^IV] at 0.78 V vs. Fc⁺/Fc, the reversible oxidation at 0.25 V vs. Fc⁺/Fc in [(ioan)Mn^IITi^IV] indicates even the access of Mn^III. These results indicate that pentanuclear complexes [(ioan)FeM¹M²M¹Fe(ioan)]ⁿ⁺ are meaningful targets to access electron delocalization in mixed-valence systems over five ions due to the facile accessibility of both Fe^II and Fe^III in the terminal positions. This study provides important local spin-Hamiltonian and Mössbauer parameters that will be essential for the understanding of the potentially complicated electronic structure in the anticipated pentanuclear complexes.     

Studies on the structure-activity relationship of delta-sleep inducing peptide

DSIP and its fourteen analogs as well as three short peptides were synthesized by solid phase method. The design of the analogs was based on the consideration of the introduction of D-amino acid into the molecules to inhibit the enzymatic hydrolysis and the introduction of amino acids with a hydrophobic side chain. The modification was placed on the position of 1, 3, 4, 5, 8 and 9, e.g. D- Trp¹, Tyr¹, Tyr¹ Phe⁵, D-Trp¹ Phe⁸, Trp^3,4, D-Trp^1,3,4 Phe⁸, D-Trp3^,4 Phe⁸ D-Glu⁹, D-pF-Phe^3,4 Phe⁸ D-Glu⁹, Phe⁵, Glu⁵ Asp⁹, Tyr⁶ Asp⁹, Asp⁹ and Ala⁷-DSIP as well as Trp-Ala-Gly-Gly-Asp, Trp-Ala-Gly-Gly-Glu and Trp-Gly-Glu. DSIP and Phe⁵-DSIP were also prepared by pentafluorophenyl ester method. The purity of the synthetic peptides was checked by amino acid analysis, elemental analysis, thin layer chromatography and paper electrophoresis. The biological assay showed that the analogs of D-Trp¹, Tyr¹, Tyr¹ Phe⁵ and Ala⁷-DSIP as well as three short peptides were inactive whereas Phe⁵-DSIP showed similar activity as that of synthetic DSIP.     

脯氨酸类N-酰胺衍生物的核磁共振研究

脯氨酸类衍生物结构独特,鲜有报道利用核磁共振（nuclear magnetic resonance,NMR）技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱（1H-1H COSY）、1H-1H质子全相关谱（1H-1H TOCSY）、1H-1H核Overhauser效应谱（1H-1H NOESY）、13C NMR、无畸变的极化转移增强法（DEPT135°）、1H-13C检出1H的异核单量子相干（1H-13C HSQC）和1H-13C检出1H的异核多键相关（1H-13C HMBC）,对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜（DMSO）中L型和D型的顺反异构体以相同的比例同时存在.     

Solvated positron chemistry. II. The reaction of hydrated positrons with Cl−, Br− and I− ions

The reaction of the hydrated positron, e_aq⁺ with Cl^?, Br^?, and I^? ions in aqueous solutions was studied by means of positron The measured angular correlation curves for [Cl^?, e⁺], [Br^?, e⁺, and [I^?, e⁺] bound states were in good agreement with th Because of this agreement and the fact that the calculated positron wavefunctions penetrate far outside the X^? ions in the [X^?, e⁺] sta propose that a bubble is formed around the [X^?, e⁺] state, similar to the Ps bubble found in nearly all liquids. F^?ions did not react w Preliminary results showed that CN^? ions react with e_aq⁺ while OH^?ions are non reactive. The rate constants were 3.9 × 10¹⁰ M^?1 s^?1, 4.4 × 10¹⁰ M^?1 s^?1, and 6.3 × 10¹⁰ M^?1 s^?1 for Cl^?, Br^?, and I^?, respectively, at low (? 0.03 M) X^? concentrations. A 25% decrease in the rate constant caused by the addition of 1 M ethanol to the I^? solutions was i The influence of halide ions on the positronium (Ps) yields in pure water was studied by use of lifetime measurements. The Cl^?, Br^?, and I^? ions reduced the Ps yields at low concentrations (? 0.03 M), while F^? ions only reduced the Ps-yield However, the Ps yields saturated (e.g. at ≈ 21% ortho-Ps yield in the Cl^? case) at higher concentrations. This saturation and the high-concentration effects-in the angular correlation results were interpreted as caused by rather complicated spur effects, wh It is proposed that spur electrons may pick off the positron from the [X^?, e⁺ states with an efficiency which depends on the structure of the     

Theoretical study of electronic structure of rhodium mononitride and interpretation of experimental spectra

Potential energy curves of 22 electronic states of RhN have been calculated by the complete active space second‐order perturbation theory method. The X¹Σ₀⁺ is assigned as the ground state, and the first excited state a³Π₀+ is 978 cm^?1 higher. The ¹Δ(I) and B¹Σ⁺ states are located at 9521 and 13,046 cm^?1 above the ground state, respectively. The B¹Σ⁺ state should be the excited state located 12,300 cm^?1 above the ground state in the experimental study. Moreover, two excited states, C¹Π and b³Σ⁺, are found 14,963 and 15,082 cm^?1 above the X¹Σ⁺ state, respectively. The transition C¹Π₁–X¹Σ₀⁺ may contribute to the experimentally observed bands headed at 15,071 cm^?1. There are two excited states, D¹Δ and E¹Σ⁺, situate at 20,715 and 23,145 cm^?1 above the X¹Σ⁺ state. The visible bands near 20,000 cm^?1 could be generated by the electronic transitions D¹Δ₂–a³Π₁ and E¹Σ⁺₀–X¹Σ⁺₀ because of the spin–orbit coupling effect. © 2013 Wiley Periodicals, Inc.     

Chelatbildung mit N-unsubstituierten 1.2-Diiminliganden

Fe^II, Co^III, Ni^II, Pd^II, and Rh^III chelates with the N-unsubstituted 1-2-diimine ligands benzildiimine and 9.10-phenanthrenequinonediimine have been prepared. The compounds are characterised chemically, spectroscopically (uv, vis, ir) and polarographically. The results indicate remarkable π-back bonding in the chelates. The unusual magnetic moments of the Fe^II, Co^III and Rh^III chelates are caused by temperature-independent paramagnetism. Fe^II, Co^III, Ni^II and Cu^II chelates of the partially deprotonated phenanthrenequinone diimine are obtained.     

Dianionic Titanyl and Vanadyl (Cation+)2[MIVO(Pc4−)]2− Phthalocyanine Salts Containing Pc4− Macrocycles

In this study, the titanyl and vanadyl phthalocyanine (Pc) salts (Bu₄N⁺)₂[M^IVO(Pc^4?)]^2? (M=Ti, V) and (Bu₃MeP⁺)₂[M^IVO(Pc^4?)]^2? (M=Ti, V) with [M^IVO(Pc^4?)]^2? dianions were synthesized and characterized. Reduction of M^IVO(Pc^2?) carried out with an excess of sodium fluorenone ketyl in the presence of Bu₄N⁺ or Bu₃MeP⁺ is exclusive to the phthalocyanine centers, forming Pc^4? species. During reduction, the metal +4 charge did not change, implying that Pc is an non‐innocent ligand. The Pc negative charge increase caused the C?N(pyr) bonds to elongate and the C?N(imine) bonds to alternate, thus increasing the distortion of Pc. Jahn–Teller effects are significant in the [eg(π*)]² dianion ground state and can additionally distort the Pc macrocycles. Blueshifts of the Soret and Q‐bands were observed in the UV/Vis/NIR when M^IVO(Pc^2?) was reduced to [M^IVO(Pc ^{. 3?})] ^{. ?} and [M^IVO(Pc^4?)]^2?. From magnetic measurements, [Ti^IVO(Pc^4?)]^2? was found to be diamagnetic and (Bu₄N⁺)₂[V^IVO(Pc^4?)]^2? and (Bu₃MeP⁺)₂[V^IVO(Pc^4?)]^2? were found to have magnetic moments of 1.72–1.78 μ_B corresponding to an S=1/2 spin state owing to V^IV electron spin. As a result, two latter salts show EPR signals with V^IV hyperfine coupling.     

Fe3+和Fe2+对原代培养的成骨细胞增殖、分化和矿化功能的影响

采用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色和茜素红染色及定量分析,研究了不同浓度的Fe3+和Fe2+对原代培养的成骨细胞增殖、分化及矿化功能的影响.结果表明:浓度为1×10-9～1×10-4 mol·L-1的Fe3+和Fe2+促进成骨细胞增殖,但是在较高浓度1×10-3 mol·L-1时,它们则抑制成骨细胞增殖.与成骨细胞作用48 h,浓度为1×10-8～1×10-4 mol·L-1的Fe3+和Fe2+抑制其分化,但在较低的浓度1×10-9 mol·L-1时则对其分化没有影响:进一步延长作用时间为72 h,Fe3+对成骨细胞分化没有影响,除1×10-6mol·L-1浓度的Fe2+促进成骨细胞分化外,其他浓度的Fe2+则抑制其分化;测试浓度下的Fe3+对成骨细胞向脂肪细胞的横向分化表现为抑制或没有影响,而Fe2+的影响则依赖于浓度和作用时间.在1×10-8～1×10-5mol·L-1浓度范围内,Fe3+和Fe2+对矿化结节的影响表现出相反的效应.在较高浓度(1×10-4mol·L-1)下,它们促进矿化节结的形成,而在较低浓度(1×10-9mol·L-1)下,Fe3+抑制矿化节结的形成,Fe2+则没有影响.结果提示:浓度.作用时间和铁离子的价态都是影响Fe3+和Fe2+生物效应(从毒性到活性,从损伤到保护,从上调到下调)转变的关键因素.     

The development of nuclear microprobe techniques for the spatial determination of13C and13C/12C ratios

Sensitive and selective nuclear reaction methods have been sought for the nuclear microprobe measurement of the spatial distributions of¹³C and¹³C/¹²C ratios. The¹³C(α, n)¹⁶O reaction, with neutron detection, is the most selective for¹³C, and has a sensitivity of ca. 100 ppm. The reactions¹³C(d, p)¹⁴C and¹²C(d, p)¹³C, with proton detection, are the most sensitive for the simultaneous measurement of¹³C and¹²C, with detection limits of 30 and 2 ppm respectively. Less sensitive alternative reaction pairs are;¹³C(³He, p)¹⁵N and¹²C(³He, p)¹⁴N;¹³C(d, nγ)¹⁴N and¹²C(d, pγ)¹³C;¹³C(³He, pγ)¹⁵N and¹²C(³He, pγ)¹⁴N. The conditions governing their use, particularly light element interferences, are detailed.     

Studies on some radical transfer reactions by entrapping the radicals as polymer endgroups. III. Reaction of ȮH radical with halide ions

The reactions of OH radical with Cl^?, Br^?, I^?, and F^? ions have been studied by entrapping the product radicals as polymer endgroup which have been detected and estimated by the sensitive dye partition technique. The rate constants of the reactions with Br^?, Cl^?, and F^? ions have been determined to be 1.51 × 10⁹, 1.32 × 10⁹, and 0.92 × 10⁹ L mol^?1 s^?1, respectively at 25°C and pH 1.00. Oxidation of I^? ions liberates I, which inhibits the polymerization and the reaction could not be followed by polymer endgroup analysis. The observed order of reactivity Br^? > Cl^? > F^? is in accordance with the electron affinities of the halide ions. The acidity of the reaction medium has a strong influence on the rate of reaction. With Br^? ions, the rate constant of the reaction falls from 1.51 × 10⁹ to 0.75 × 10⁹ L mol^?1 s^?1 at 25°C as the pH is raised from 1.0 to 2.8. The method is simple and accurate and can be applied to study very reactive radicals.     

Photodissociation Spectra of OCS+ via B2∑+←X2∏ Transitions

In the wavelength range of 231-275 nm, we have studied the mass-resolved dissociation spectra of OCS⁺ via B²∑⁺←X²∏_3/2(000) and B²∑⁺←X²∏_1/2(000, 001) transitions by preparing OCS⁺ ions in the well-defined spin-orbit states. The spectroscopic constants ofυ1(CS stretch)=828.9 (810.4) cm^-1, υ2(bend)=491.3 cm^-1 and υ3(CO stretch)=1887.2 cm^-1 for OCS⁺(B²∑⁺) are deduced. The observed dependence of the υ2(bend) mode excitation of B²∑⁺ on the spin-orbit splitting of X²∏(Ω=1/2, 3/2) in the B²∑⁺←X²∏ transition can be attributed to the K coupling between the (000)²∏_1/2 and (010)²∑⁺_1/2 vibronic levels of X²∏ state, which makes the B²∑⁺(010)←X²∏_1/2(000) transition possible.     

Calculations on bound and autoionizing states,and continuum radiative properties for Li− and Na−

Semi-empirical model potential calculations have been performed for bound and continuum properties of Li^? and Na^?. The calculated electron affinities of the 2s²¹S state of Li^? and the 3s²¹S and 3p²³P^e states of Na^? are in agreement with the calculations of Norcross and with experimental data. Positions of possible autoionizing states are calculated using projection and root stabilization methods. The Stieltjes imaging method of Langhoff is employed to compute the photodetachment cross sections of Li^? and Na^? and the results are in excellent agreement with the close-coupling calculations of Moores and Norcross. A comparison of variational and numerical results for the coupled time-dependent Hartree-Fock photoionization of helium shows that good Stieltjes imaging results can be obtained with a very small basis set for the variational calculation. The continuous photoemission profile for the 3p²³P^e state of Na^? is also obtained.     

Radioactivity of coals and fly ashes

The level and the behavior of the naturally occurring primordial radionuclides ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, ²²⁸Ra and ⁴⁰K in coals and fly ashes are described. The activity concentrations of the examined coals and originated from coal mines in Greece ranged from 117 to 435 Bq·kg⁻¹ for ²³⁸U, from 44 to 255 Bq·kg⁻¹ for ²²⁶Ra, from 59 to 205 Bq·kg⁻¹ for ²¹⁰Pb, from 9 to 41 Bq·kg⁻¹ for ²²⁸Ra and from 59 to 227 Bq·kg⁻¹ for ⁴⁰K. These levels are comparable to those appeared in coals of different countries worldwide. The activity concentrations of the examined fly ashes and produced in coal-fired power plants in Greece ranged from 263 to 950 Bq·kg⁻¹ for ²³⁸U, from 142 to 605 Bq·kg⁻¹ for ²²⁶Ra, from 133 to 428 Bq·kg⁻¹ for ²¹⁰Pb, from 27 to 68 Bq·kg⁻¹ for ²²⁸Ra and from 204 to 382 Bq·kg⁻¹ for ⁴⁰K. The results showed that there is an enrichment of the radionuclides in fly ash relative to the input coal during the combustion process. The enrichment factors (EF) ranged from 0.60 to 0.76 for ²³⁸U, from 0.69 to 1.07 for ²²⁶Ra, from 0.57 to 0.75 for ²¹⁰Pb, from 0.86 to 1.11 for ²²⁸Ra and from 0.95 to 1.10 for ⁴⁰K.     

Simultaneous determination of lead(II) and cadmium(II) at a diacetyldioxime modified carbon paste electrode by differential pulse stripping voltammetry

A simple and effective chemically modified carbon paste electrode (CMCPE) for the simultaneous determination of lead(II) and cadmium(II) was developed in this work. The electrode was prepared by the addition of diacetyldioxime into a carbon paste mixture. Pb²⁺ and Cd²⁺ were preconcentrated on the surface of the modified electrode by complexing with diacetyldioxime and reduced at a negative potential (−1.10 V). Then the reduced products were oxidized by differential pulse stripping. The fact that two stripping peaks appeared on the voltammograms at the potentials of −0.65 V (Cd²⁺) and −0.91 V (Pb²⁺) demonstrates the possibility of simultaneous determination of Pb²⁺ and Cd²⁺. Under the optimized working conditions, calibration graphs were linear in the concentration ranges of 1.0×10⁻⁷-1.5×10⁻⁵ mol l⁻¹ (Pb²⁺) and 2.5×10⁻⁷-2.5×10⁻⁵ mol l⁻¹ (Cd²⁺), respectively. For 5 min preconcentration, detection limits of 1×10⁻⁸ mol l⁻¹ (Pb²⁺) and 4×10⁻⁸ mol l⁻¹ (Cd²⁺) were obtained at the signal noise ratio (SNR) of 3. To evaluate the reproducibility of the newly developed electrode, the measurements of 5×10⁻⁷ mol l⁻¹ Pb²⁺ and Cd²⁺ were parallel carried out for six times at different electrodes and the relative standard deviations were 2.9% (Pb²⁺) and 3.2% (Cd²⁺), respectively. Interferences by some metals were investigated. Only Ni²⁺ and Hg²⁺ apparently affected the peak currents of Pb²⁺ and Cd²⁺. The diacetyldioxime modified carbon paste electrode was applied to the determination of Pb²⁺ and Cd²⁺ in water samples. The results indicate that this electrode is sensitive and effective for the simultaneous determination of Pb²⁺ and Cd²⁺.     

Metal chelates of thiazole-2-ylthiourea

Summary The formation constants of 1-phenyl-3-thiazole-2-ylthiourea complexes with some bivalent metal ions (Cu^II, Ni^II, Zn^II and Mn^II) have been determined in 75% EtOH–H₂O. Complexes of Cu^II, Ni^II, Zn^II, Hg^II and Pd^II have been isolated and characterized by conductance, i.r., electronic spectra and magnetic measurements. The ligand forms ML complexes with Cu^II and Hg^II and ML₂ with Ni^II, Zn^II and Pd^II, where L is the uninegatively charged bidentate ligand and binds through the ring nitrogen and thiocarbonyl sulphur atoms.