Hyperfine structure in the configurations4f 4 6s 2 and4f 4 5d 6s of Nd I

The high resolution laser-atomic-beam technique was used to investigate the hyperfine structure in Nd I 4f ⁴6s ^{2 5} I,⁵ F,⁵ S and 4f ⁴5d6s ⁷ L,⁷ K,⁷ I,⁷ H. The metastable states were populated by an arc discharge burning in the atomic beam. The measured hyperfine constantsA andB of the levels of 4f ⁴6s ² and 4f ⁴5d6s allow a parametric analysis to be performed using the effective tensor operator formalism. The experimental radial integrals of the 4f and 5d electrons fit with those of the other lanthanides. The 4f radial integrals are in agreement with values of optimized Hartree-Fock-Slater calculations. The spectroscopic quadrupole moments of¹⁴³Nd and¹⁴⁵Nd are deduced from the 4f parameters:Q _I =?0.610(21) b and ?0.314(12) b, respectively. TheQ _I resulting from the 5d parameter are in satisfactory agreement with these values. The hyperfine anomaly due to thes electron in 4f ⁴5d 6s amounts to about 1%.     

Fine structure of the 1s5f and 1s5g levels of He I

The fine structure of the 1s5f and 1s5g levels of He I was measured using microwave spectroscopy. The helium atoms were excited by ion impact, and the eleven allowed 1s5f ^2S+1 F _J –1s5g ^2S′+1 G _J , transitions near ν≈15 GHz were induced and detected by measuring the 1s4d–1s2p or 1s3d–1s2p spectral-line intensities of the impact radiation as a function of the microwave frequency. The measured transition frequencies are in accord with theoretical values and, except for one transition frequency, with earlier experimental data. The existing discrepancy between these earlier data and theory could be solved.     

Crystal structure and magnetic structure of TbOOH

The monoclinic modification of terbium oxide hydroxide, TbOOH, was prepared using hydrothermal technique. The crystal structure was investigated by three-dimensional single-crystal X-ray analysis and was refined to a conventional R-value of 8.1%. The space group is $\text{P2}{}_1\text{m}$, No. 11, with a = 6.04 Å, b = 3.69 Å, c = 4.33 Å, and β = 109.0°. The terbium atom is seven coordinated with oxygen atoms, and the structure is not hydrogen bonded.The compound is antiferromagnetic with a Néel temperature of 10°K. Neutron diffraction powder patterns were measured at 300°K and 4.2°K. The magnetic super lattice reflections were indexed on the basis of a monoclinic unit cell with the dimensions a_M = 2a, b_M = b, c_M = c, and β_M = β, where a, b, c, and β are the dimensions of the chemical unit cell. The structure contains two independent magnetic atoms. A nonclinear antiferromagnetic arrangement of the spins describes the magnetic structure. The spin at one atom has an angle of 43° with the ac plane and the projection of the spin on the ac plane has an angle of 59° with the a axis. The spin on the other atom has an angle of ?43° with the ac plane, the projection having the same angle of 59° with the a axis.     

Calixarene coated gold nanoparticles as a novel therapeutic agent

In the current study, gold nanoparticles (AuC6NPs and AuC8NPs) were prepared through sodium borohydride reduction method by using Calix[6]rene and Calix[8]rene as a stabilizing agents. The synthesized AuNPs were screened for cytotoxic, phytotoxic, antifungal and antibacterial activities. The fabricated AuNPs were characterized by UV–visible spectroscopy, atomic force microscopy (AFM) and FTIR spectroscopy. Antibacterial activities of the AuNPs were tested against E. coli and S. aureus. The AuC6NPs were found to be effective against the growth of gram positive bacteria and inhibited the growth of S. aureus. AuC6NPs interact with bacterial cell and damaged cell membrane. Roughness of the bacterial surface and membrane rupture can be clearly observed by AFM images. The AuNPs possess insignificant antifungal activity against Aspergillus niger and Candida albicans. Moreover, AuC8NPs have significant phytotoxicity and moderate cytotoxicity.     

Bound state energies for the exponential cosine screened Coulomb potential

The energy eigenvalues of bound states of an electron in the general exponential cosine screened Coulomb potential are obtained using the shifted 1/N expansion method. The energies for the states from 1s to 8k are calculated from six to eight significant figures. The energy eigenvalues for the 1s, 2s – 2p, 3s – 3d, and 4s – 4f states are also presented as a function of the screening parameter λ. Results are compared with the ones obtained by other workers. The agreement reduces roughly for large λ. It is also observed that the convergence of the expansion series increases remarkably asl increases.     

Enantiomerically pure 4-amino-1,2,3-trihydroxybutylphosphonic acids

(1S,2R,3S)-, (1R,2R,3S)- and (1S,2R,3R)-4-amino-1,2,3-trihydroxybutylphosphonic acids were synthesised. The synthetic strategy involved preparation of the respective 4-azido-2,3-O-isopropylidene-l-threose or -d-erythrose, addition of dialkyl phosphites, separation of C-1 epimeric O,O-dibenzyl phosphonates, the reduction of azides and the removal of the protecting groups. The (2R,3S) and (2R,3R) configurations in the final products were secured by employing diethyl l-tartrate and d-isoascorbic acid as starting materials. The stereochemical course of the addition to the carbonyl groups in 4-azido-2,3-O-isopropylidene-l-threose or -d-erythrose followed that established earlier for 2,3-O-isopropylidene-d-glyceraldehyde and similar (3:1-4:1) diastereoselectivities were achieved.     

Electronic structure and magnetic properties of TMRh12 clusters

We report an experimental study of energy pooling collisions involving Cs atoms in the 6P and 5D states. The 5D state was populated by a cw dye-laser tuned to the cesium dipole-forbidden transition 6S → 5D at 685.0 nm. The 6P state was populated by subsequent radiative relaxation of the 5D state. The 6P population density was determined from the absorption of a cw diode-laser probe beam. The population densities of the 5D state and the higher, by energy pooling excited states were determined by measuring the corresponding fluorescence intensities relative to the fluorescence intensity from the optically thin quasi-static wings of the cesium D ₂ line. The rate coefficient for the process Cs*(6P)+Cs*(6P)→Cs**(6D)+Cs(6S) is found to be (4.2±0.13)×10^?10 cm³ s^?1 at T=570 K. In addition, estimates of the rate coefficients for the processes Cs*(6P)+Cs*(5D)→Cs**(7D)+Cs(6S) and Cs*(5D)+ Cs*(5D)→Cs**(7F)+Cs(6S) are given.     

Factors affecting the ultramicro-determination of tryptophan,kynurenine and their derivatives

The factors affecting the ultramicrodetermination of tryptophan and kynurenine were investigated by paper electrophoresis, paper chromatography and spectrophotometry. The electrolyte used in electrophoresis influences the mobility, the separation and the ultraviolet spectra of tryptophan and kynurenine. The pre-treatment of filter paper for chromatography did not influence the R_F of tryptophan and kynurenine, but interfered with their quantitative determination. The effect of ultraviolet irradiation of d-, l-, and dl-tryptophan as well as d-, l-, and dl-kynurenine was studied.     

Effect of blending way on β-crystallization tendency of compatibilized β-nucleated isotactic polypropylene/poly(ethylene terephthalate) blends

The main purpose of this study is to investigate the β-crystallization tendency in the β-nucleated iPP blends. The β-nucleated iPP/compatibilizers blends, β-nucleated iPP/PET blends and its compatibilized versions with four kinds of compatibilizers (PP-g-MA, PP-g-GMA, POE-g-MA, and EVA-g-MA) were prepared by different blending ways. The effect of compatibilizers and blending ways on the non-isothermal crystallization and melting characteristics and the β-crystallization tendency of β-nucleated iPP blends were studied by differential scanning calorimetry. The relative content of the β-phase were characterised by the k _β values determined on the basis of the wide angle X-ray diffractogram. The results indicated that the β-crystallization tendency of β-nucleated iPP blends depends on the kinds of compatibilizer. Addition of PP-g-MA significantly reduced the β-crystallization tendency of β-nucleated iPP, while PP-g-GMA, POE-g-MA, and EVA-g-MA have little effect on it. In the compatibilized β-nucleated iPP/PET blends, the blending ways, which controlled the dispersion of β-nucleating agent, influences the β-crystallization tendency intensively. The high β-crystallization tendency and β-crystal content were obtained for compatibilized β-nucleated iPP/PET blends prepared firstly at high temperature and β-nucleating agent added into blends at low temperature; however, the type of compatibilizers has little effect on β-crystallization tendency and melting behavior of blends.     

Synthesis and antibacterial properties of new phenothiazinyl- and phenyl-nitrones

The synthesis of new phenothiazinyl- and phenyl-nitrones under classical versus microwave heating conditions is described. Better yields were obtained under microwave irradiation in the condensation reactions of phenothiazyl-carbaldehyde with hydroxylamine derivatives. The structures of the new phenothiazinyl-nitrones were assigned on the basis of MS, FT–IR and NMR spectra. The new nitrones and some known phenyl-nitrones were screened for their antibacterial and antifungal activity against several Candida species, Gram negative bacteria, such as E. coli, Citrobacter spp, Morganella spp, Pseudomonas aeruginosa, Klebsiella pneumoniae (± ESBL), Proteus spp, Acinetobacter spp and the Gram positive bacterium Staphylococcus aureus, with moderate results.     

Stability of Rare-Earth Oxychloride Phases: Bond Valence Study

The crystal structures of the tetragonal rare earth (RE) oxychlorides, REOCl (RE=La-Nd, Sm-Ho, and Y) were studied by X-ray powder diffraction measurements, Rietveld analyses, and bond valence calculations. The tetragonal structure (space group P4/nmm, No. 129, Z=2) is stable for all but Er-Lu oxychlorides, which possess a hexagonal structure. The tetragonal structure consists of alternating layers of (REO)_nⁿ⁺ complex cations and Xⁿ⁻ anions, where the rare earth is coordinated to four oxygens and four plus one chlorines in a monocapped tetragonal antiprism arrangement. The Rietveld analyses yielded a coherent series of structural parameters. Preferred orientation and microabsorption effects were found significant. The evolution of interatomic distances and bond angles indicated that the reason for the preferred structure changing from tetragonal to hexagonal is the strain in the chlorine layer. The bond valence parameter B for the RE-O bonds had to be recalculated due to the covalent nature of the (REO)_nⁿ⁺ unit. The results obtained with the new parameter confirmed the strains in the chlorine layer to be the cause for the phase transition.     

Fine structure and transition probabilities of the 2p 5 nl bound excited states of Ne atom

We present a semi-empirical calculational procedure for thep ⁵ nl bound excited states of rare gas atoms based on the use of an LS-dependent orbital for an excitednl electron outside a frozen Hartree-Fockp ⁵ core. The spin-orbit interaction is accounted for approximately using a localized Hartree potential. The contribution from the long-range core polarization is estimated by using a parametrized potential. A model potential is also introduced to represent partially the short-range multi-electron interactions for thep ⁵ np levels. The energy levels are calculated by diagonalizing the Hamiltonian matrix following anLS →jl transformation. The calculated fine structure of the Nep ⁵ ns,p ⁵ np,p ⁵ nd, andp ⁵ nf ¦ (jl)KJ〉 levels are in close agreement with the observed level splittings. The transition probabilities are also in agreement with earlier theoretical and experimental results.     

An improved model of the fringing fields of a quadrupole mass filter

The fringing field region of a quadrupole mass filter is modelled using an iterative finite difference technique to solve Laplace's equation for the electrostatic potential. The results are used to formulate an expression f(z) such that the electrostatic potential of the fringing field, F(x, y, z, t) may be written in the form F(x, y, z, t) = f(z) φ(x, y, t), where φ(x, y, t) is the hyperbolic field of the quadrupole. The function f(z) is expressed in the form f(z) = 1 - exp {- az - bz²}), where a and b are constants and z is in units of r_O, where 2r_O is the spacing of the quadrupole rods. The effect of the distance from the quandrupole rods to the end plate of the quadrupole mass filter, d on f(z) is investigated and the results presented show that for d < 0.125 r_O the function f(z) does not alter significantly.     

Semiclassical variational study of size effects in neutral and charged jellium droplets

An analytic expression for the total energy of metallic clusters composed ofN identical atoms of valencev and with net chargeQ is obtained by means of a variational solution of the Thomas-Fermi-Weizsäcker energy density functional within the spherical jellium model. The minimum energy is given as an expansion in decreasing powers of the cluster radiusR=r _s Z ^1/3, withZ=vN andr _s the radius per electron of the bulk metal. The coefficients are obtained as functions ofr _s . Terms of volume (R ³), surface (R ²), curvature (R), constant (R ⁰), (1/R) and (1/R ²) are clearly separated in the formula, as well as the different contributions (kinetic, coulombic and exchange-correlation) to each of them. The asymptotic values (R→∞) for the work functions,W(r _s ), and surface energies σ(r _s ), are compared to analogous semiclassical and Kohn-Sham calculations of jellium-like surfaces and to the experimental values. The size dependent behaviour of chemical potentials, μ(R), electron affinities,AF(R), and ionization potentials,IP(R), are easily obtained for any kind of metallic clusters. In particular we discuss the Coulomb and quantum corrections to the coefficients β, δ in the asymptotic formulae:IP?W+β/R andAF?W+δ/R.     

Molecular energy parameters by solution thermodynamics

The relationships between statistical thermodynamics and equilibrium constants, either cumulative, stepwise or specific site constants are investigated. In order to show the link between equilibrium constants and statistical thermodynamic microscopic properties, a distinction has been introduced between non-reacting and reacting systems. The non-reacting systems are those for which continuous statistical distributions of enthalpies can be assumed. The distribution function can be obtained as an integral of the interparticle potential extended to the whole ensemble. Molecular partition functions ζ_A, are used to describe the properties of the ensembles. The reacting ensemble is represented by distinct distributions of enthalpies, each distribution being grouped around a mean value. Each level is representative of one species. Around each mean level the distribution is continuous as in non-reacting ensembles. The reacting ensemble of particles is described by a grand canonical molar partition function Z_M=(1+kγ(i)[A])^t where k is the specific site constant, γ(i) is the cooperativity function, [A] is the concentration of free ligand, and the power t indicates the maximum number of i sites in one class. The specific site constant k is proportional to the affinity of binding and is related to the depth of the minimum of the potential function. The factor γ_i is the cooperativity factor given by the value of the cooperativity function γ(i) at the ith level and indicates how the depth of the potential function is affected by previous binding of a ligand. The values of the stability constant and cooperativity factor can be optimized by a computer program. The derivatives of the partition function Z_M with respect to ln[A] correspond to the formation function 〈n〉 (first derivative) and to the buffer capacity B_C (second derivative). The derivatives of the partition function Z_M with respect to temperature are reaction enthalpy ΔH (first derivative with −(1/T)) and apparent heat capacity ΔC_p,app (second derivative with ln T). The denaturation heat obtained by integration of ΔC_p,app dT for many proteins explains why the denaturation enthalpy depends linearly upon T.     

Thermodynamic, IR spectral and X-ray diffraction studies of the ����-cyclodextrin-para-aminobenzoic acid�� inclusion complex

The inclusion complex with stoichiometric composition 1:1 was formed as a result of intermolecular interactions between para-aminobenzoic acid and ??-cyclodextrin. The stability constant of ????-cyclodextrin-para-aminobenzoic acid?? inclusion complex at 289, 292 and 313 K was calculated by the Ketelar equation. The influence of temperature on the stability of ????-cyclodextrin-para-aminobenzoic acid?? inclusion complex was also examined, and thermodynamic parameters involved in the complex formation (??G, ??H, ??S) were calculated. Supramolecular complex formation between para-aminobenzoic acid and ??-cyclodextrin was confirmed by X-ray diffraction and IR spectroscopy studies.     

Stereoselective total synthesis of protected sulfamisterin and its analogues

The stereoselective synthesis of sulfamisterin I and its unnatural analogues II and V in their protected form was achieved through a common strategy. The Wittig reaction of aldehydes VIII and IX with the C₁₄ hydrophobic side-chain X served as the key C-C connecting transformation. Subsequent functional group inter-conversions in the coupling products XI and XX completed the total synthesis.     

Stereoselective synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-ol and its propionate,the sex pheromones of pine sawflies

The stereoselective synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-ol (diprionol) and its propionate, the sex pheromones of pine sawflies (Neodiprion sp. and other), in high enantiomeric purity was achieved from (1R,3S)-2,2-dichloro-3-methylcyclopropanecarboxylic acid. The carbon skeleton of diprionol was formed via copper-catalyzed cross-coupling reactions and diastereoselective methylation of the intermediate chiral α-methylbranched aldehyde with MeTi(Oi-Pr)₃ in the presence of [(R,R)-TADDOL]Ti(Oi-Pr)₂. The latter transformation leads to a syn-adduct with high stereoselectivity, which depends on the presence and configuration of the α-stereogenic center in the aldehyde. The diastereomeric purity of (2S,3S,7S)-diprionol can be substantially increased via crystallization of its 3,5-dinitrobenzoate.     

Microdetermination of aliphatic amines and polyamines with cupric ion: Relationship between pK1 and half-complexation potential

The first equilibrium constant for the combination of ligand with cupric ion, K₁, is related to the half-complexation potential, E_HC, by log K₁ = a + b[E_HC]. The coefficients differ for n ? 2 and n ? 2, where n is the number of nitrogen atoms in the molecule. The correlation coefficients, r, based on data available from the literature were ?0.98. The equations can be used for estimating log K₁ of aliphatic amines. Successful titration of aliphatic amines vs cupric ion requires log K₁ ? 4 and an initial pH of a 10^?3M solution of ?9.     

Aronia melanocarpa (Michx.) Elliot,Chaenomeles superba Lindl. and Cornus mas L. Leaf Extracts as Natural Preservatives for Pork Meat Products

The aim of this study was to investigate the possibility of using Aronia melanocarpa, Chaenomeles superba, and Cornus mas leaf extracts as natural preservatives for pork meat products. Pork sausages were stored in modified atmosphere packaging (MAP) (80% N₂ and 20% CO₂) at 4 °C for 29 days. The total psychrotrophic counts (TPC) were determined during the storage period, along with the numbers of Enterobacteriaceae and lactic acid bacteria (LAB). The extracts improved the microbial quality of the meat products but to a lesser extent than sodium nitrate (III). They reduced the amounts of Enterobacteriaceae and LAB. The A. melanocarpa leaf extract showed the strongest preservative effect. The bacterial biodiversity of the meat products was investigated based on high-throughput sequencing of the 16S rRNA gene. Two predominant bacteria phyla were identified, Proteobacteria and Firmucutes, mostly consisting of genera Photobacterium, Brochothrix, and Carnobacterium. The extracts also influenced microbial community in sausages decreasing or increasing bacterial relative abundance. The extracts significantly inhibited lipid oxidation and improved the water-holding capacity of the meat, with C. superba extract showing the strongest influence. In addition, A. melanocarpa and C. superba improved the redness (a*) of the sausages. The results of this study show that A. melanocarpa, C. superba, and C. mas leaf extracts can extend the shelf life of meat products stored in MAP at 4 °C.