Sm System Research Articles

Quantifying the Transmit Diversity Order of Euclidean Distance Based Antenna Selection in Spatial Modulation

In this letter, we quantify the transmit diversity order of the SM system operating in a closed-loop scenario. Specifically, the SM system relying on Euclidean distance based antenna subset selection (EDAS) is considered and the achievable diversity gain is evaluated. Furthermore, the resultant trade-off between the achievable diversity gain and switching gain is studied. Simulation results confirm our theoretical results. Specifically, at a symbol error rate of about ${10^{ - 4}}$ the signal-to-noise ratio gain achieved by EDAS is about 7 dB in case of 16-QAM and about 5 dB in case of 64-QAM.

Angular distributions of the alpha particle production in the 7Li+144Sm system at near-barrier energies

We have studied the production of alpha particles in reactions induced by 7Li projectiles on a 144Sm target at bombarding energies of 18, 24 and 30 MeV over the 15°-140° angular range. The purpose of the investigation has been to determine the contribution of different mechanisms in reactions that involve weakly bound projectiles. We have included in our analysis several processes that can either directly or sequentially lead to the emission of alpha particles: complete fusion, direct transfer of 3H, capture breakup (incomplete fusion, sequential complete fusion) and non-capture breakup. In order to distinguish alpha particles stemming from these processes it is necessary to determine the mass and charge of the reaction products and to obtain precise measurements of their energies and scattering angles over relatively wide ranges of these variables. We have done this using a detection system consisting of an ionization chamber plus three position sensitive detectors. We present results of these measurements and a preliminary interpretation based on kinematical considerations and comparisons with predictions from a statistical model.

Quadrature Spatial Modulation

This paper proposes a new multiple-input–multiple-output (MIMO) technique called quadrature spatial modulation (QSM). QSM enhances the overall throughput of conventional SM systems by using an extra modulation spatial dimension. The current SM technique uses only the real part of the SM constellation, and the proposed method in this paper extends this to in-phase and quadrature dimensions. It is shown that significant performance enhancements can be achieved at the expense of synchronizing the transmit antennas. Additionally, a closed-form expression for the pairwise error probability (PEP) of generic QSM system is derived and used to calculate a tight upper bound of the average bit error probability (ABEP) over Rayleigh fading channels. Moreover, a simple and general asymptotic expression is derived and analyzed. Obtained Monte Carlo simulation results corroborate the accuracy of the conducted analysis and show the significant enhancements of the proposed QSM scheme.

Screening of factors influencing the photocatalytic activity of TiO2:Ln (Ln = La, Ce, Pr, Nd, Sm, Eu and Gd) in the degradation of dyes

In this work, we analyzed the photocatalytic activity of TiO2:Ln (Ln=La, Ce, Pr, Nd, Sm, Eu and Gd) systems in the degradation of two organic dyes by means of a probabilistic approach to screen the factors influencing their photocatalytic activity. The photocatalytic properties were described by six responses (crystallite size, band gap energy, visible light absorption, specific surface area, zeta potential and photocatalytic conversion) as a function of lanthanide type (seven elements), lanthanide concentration (two), pH level (two) and dye type (methyl orange and crystal violet). We analyzed 140 experiments using the analysis of variance (ANOVA) method. The results show that band gap energy and specific surface area exhibited behavior that depended on the atomic number of the element used. However, visible light absorption was not modified by the type of lanthanide element or its concentration in the range studied (0.1 and 0.3wt.% lanthanides/TiO2 ratio), and the zeta potential depended mainly on pH. Photocatalytic conversion depended on pH, dye type and doping element. The experimental factorial design of the photocatalytic system allowed us to find the best conditions for enhancing the degradation of these two dyes.

Thermodynamic Properties of Alloys of the Binary Al-Sm, Sm-Sn and Ternary Al-Sm-Sn Systems

Mixing enthalpies of the liquid binary Al-Sm (0 < xSm < 0.15; 0.37 < xSm < 1), Sm-Sn (0 < xSn < 0.13; 0.56 < xSn < 1) alloys and ternary Al-Sm-Sn alloys (along the three concentration sections: (Sm0.87Sn0.13)1−xAlx (0 < x<0.32); (Sm0.44Sn0.56)1−xAlx (0 < x<0.12); (Al0.85Sm0.15)1−xSnx (0 < x<0.032)) were determined by an isoperibolic calorimetry technique at 1410-1670 K. Thermodynamic properties of liquid Al(Sn)-Sm alloys were described in the whole concentration range using the model of ideal associated solution. Thermodynamic activities of components of the Al(Sn)-Sm melts demonstrate large negative deviation from the ideal behavior, and the mixing enthalpies are characterized by significant exothermic effects. The minimum value of the mixing enthalpy of the Al-Sm melts is −47.1 ± 0.5 kJ/mol at xSm = 0.35 (T = 1500 K, undercooled melt), Sm-Sn is −67.7 ± 0.5 kJ/mol at xSn = 0.48 (T = 1450 K, undercooled melt). The obtained results were compared with the data from survey of the binary Al(Sn)-Sm systems and with the values calculated by the different models from the data for the binary boundary subsystems of the ternary Al-Sm-Sn system.

Derivative of plant phenolic compound inhibits the type III secretion system of Dickeya dadantii via HrpX/HrpY two-component signal transduction and Rsm systems.

The type III secretion system (T3SS) is a major virulence factor in many Gram-negative bacterial pathogens and represents a particularly appealing target for antimicrobial agents. Previous studies have shown that the plant phenolic compound p-coumaric acid (PCA) plays a role in the inhibition of T3SS expression of the phytopathogen Dickeya dadantii 3937. This study screened a series of derivatives of plant phenolic compounds and identified that trans-4-hydroxycinnamohydroxamic acid (TS103) has an eight-fold higher inhibitory potency than PCA on the T3SS of D. dadantii. The effect of TS103 on regulatory components of the T3SS was further elucidated. Our results suggest that TS103 inhibits HrpY phosphorylation and leads to reduced levels of hrpS and hrpL transcripts. In addition, through a reduction in the RNA levels of the regulatory small RNA RsmB, TS103 also inhibits hrpL at the post-transcriptional level via the rsmB-RsmA regulatory pathway. Finally, TS103 inhibits hrpL transcription and mRNA stability, which leads to reduced expression of HrpL regulon genes, such as hrpA and hrpN. To our knowledge, this is the first inhibitor to affect the T3SS through both the transcriptional and post-transcriptional pathways in the soft-rot phytopathogen D. dadantii 3937.

ChemInform Abstract: Unexpected Transformation of Aldehydes into Benzoins with Copper(I)/Samarium.

Abstract The reductive coupling of aldehydes to afford pinacolic alcohols using all kinds of reducing agents involving samarium is well known. In this report, however, treatment of aromatic aldehydes with Cu(I)/Sm system produces benoins and/or benzils in good yields. A possible mechanism is proposed where Cu(I) not only activates the Sm metal but also promotes the dehydrogenation of the intermediates, during which a Cu(III) species may be involved. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

Electrochemical investigation of the redox couple Sm(III)/Sm(II) on a tungsten electrode in molten LiF–CaF2–SmF3

This article is focused on the electrochemical investigation (cyclic voltammetry and related studies) of the redox couple Sm(III)/Sm(II) in an eutectic LiF–CaF2 melt containing SmF3. The first step of reduction for Sm(III) ions involving one electron exchange in soluble/soluble Sm(III)/Sm(II) system was found on a tungsten electrode. The study of the Sm(II)/Sm(0) electrode reaction was not feasible, due to insufficient electrochemical stability of LiF–CaF2. The first step was found reversible at temperatures 1,075 and 1,125 K up to polarization rate 1 V/s and at temperature 1,175 K the process was reversible at all sweep rates applied in this study. The diffusion coefficients (D) of Sm(II) and Sm(III) ions were determined by cyclic voltammetry, showing that D decreases when oxidation state increase, while the activation energy of diffusion (Ea) increases. The standard rate constants of charge transfer (ks) were calculated for the redox couple Sm(III)/Sm(II) at 1,075 and 1,125 K based on the data of cyclic voltammetry.

Discovery of a meta-stable Al–Sm phase with unknown stoichiometry using a genetic algorithm

Unknown crystalline phases observed during the devitrification process of glassy metal alloys significantly limit our ability to understand and control phase selection in these systems driven far from equilibrium. Here, we report a new meta-stable Al5Sm phase identified by simultaneously searching Al-rich compositions of the Al–Sm system, using an efficient genetic algorithm. The excellent match between calculated and experimental X-ray diffraction patterns confirms that this new phase appeared in the crystallization of melt-spun Al90Sm10 alloys.

Sliding manifold design for linear systems with unmatched disturbances

This paper offers an efficient sliding manifold design method that minimizes the impact of unmatched disturbances onto SM dynamics and system accuracy. System sensitivity upon unmatched constant or slowly varying external disturbance vector is evaluated by the steady-state dependent criterion function. An infinite set of sliding manifolds that minimize the chosen optimization criterion is determined and a way of selecting a manifold out of that set that provides adopted SM dynamics is suggested. The proposed approach has been demonstrated on numerical examples and verified by simulations.

Differential and total cross sections of noncapture breakup reactions in the6Li+144Sm system

Fil: Martinez Heimann, Diego. Consejo Nacional de Investigaciones Cient__itilde__ficas y T__etilde__cnicas; Argentina. Comision Nacional de Energia Atomica. Gerencia del Area de Investigacion y Aplicaciones No Nucleares. Gerencia Fisica. (Centro Atomico Constituyentes) Proyecto Tandar; Argentina

Thermodynamic modeling and experimental investigation of the magnesium–zinc–samarium alloys

Magnesium (Mg)–Zinc (Zn)–Samarium (Sm) alloy system is being considered for the development of high-strength novel Mg alloys for structural applications. In this work, ternary phases in Mg–Zn–Sm system at Mg-rich corner were identified experimentally, based upon the investigation of five key alloys. Phase relationships at 350, 400 and 450°C of this system were also established. Furthermore, a self-consistent thermodynamic description of Mg–Zn–Sm system at Mg-rich corner was developed for the first time using the CALPHAD (CALculation of PHAse Diagram) method. Good agreement between the calculated phase diagrams and the experimentally measured data from both this study and literature validated the thermodynamic modeling approach used in this work.

Thermodynamic properties of melts of the binary Ag(Au)-Sm systems

The enthalpies of mixing for liquid alloys of the Ag-Sm system are determined by isoperibolic calorimetry at 1450–1506 K in the 0.46 < x Sm < 1 range of concentrations. The partial and integral enthalpies of mixing for melts of the Ag-Sm system are obtained over the whole range of concentrations. The activities of components and the entropy of mixing in melts of the Ag-Sm system at 1506 K are calculated using a model of ideal associated solutions (IAS). The partial and integral enthalpies of mixing for melts of the Ag-Sm system, the activities of the components, and the molar fractions of associates in them are calculated using the IAS model. It is concluded that the thermodynamic activities of components in melts of the Ag (Au)-Sm system at 1506 K exhibit great negative deviation from the ideal behavior, and the enthalpies of mixing indicate there are considerable exothermal effects.

Studies of DNA Breathing and Helicase Mechanisms by Single Molecule (SM) Fret Between 6-MI and Cy3 in DNA Replication Fork Constructs

6-methyl isoxanthopterin (6-MI) is a fluorescent nucleotide base analog of guanine (G) that can be site-specifically substituted for G at key positions within a DNA construct, with little or no disruption of the normal nucleic acid structure. DNA constructs fluorescently labeled with 6-MI have been useful in probing local base conformational changes in bulk solution experiments, but to date no experiments with 6-MI have been undertaken at the single molecule level. Major challenges towards achieving this goal include working with fluorophores with small extinction coefficients (e350 nm ∼ 12000 M-1cm-1) in the UV, and the necessity to separate weak fluorescence from scattered laser excitation light.We here report sm experiments performed on 6-MI-labeled DNA constructs that were resonantly excited using the 351 nm line of an argon ion laser in combination with a home-built total internal reflection fluorescence (TIRF) microscope and split-screen CCD camera. To investigate the feasibility of such sm fluorescence experiments we used a long biotinylated DNA strand (91-mer) that provided binding sites for a short DNA molecule (23-mer) containing three 6-MI residues. From experiments on this substrate we were able to monitor three successive photo-bleaching steps, indicating the presence of the three 6-MI chromophores. We next developed a new Forster resonance energy transfer sm(FRET) system between 6-MI and the carbocyanine dye Cy3 site-specifically inserted into the DNA backbone of a fork construct. By performing experiments in bulk solution and at the sm level, we were able to demonstrate smFRET between a 6-MI probe at the fork junction and a Cy3 backbone probe within the dsDNA of the fork. We are now using this approach to study DNA unwinding mechanisms by the bacteriophage T4 helicase−primase (primosome) complex.

Unexpected Transformation of Aldehydes into Benzoins with Copper(I)/Samarium

The reductive coupling of aldehydes to afford pinacolic alcohols using all kinds of reducing agents involving samarium is well known. In this report, however, treatment of aromatic aldehydes with Cu(I)/Sm system produces benoins and/or benzils in good yields. A possible mechanism is proposed where Cu(I) not only activates the Sm metal but also promotes the dehydrogenation of the intermediates, during which a Cu(III) species may be involved. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

Complete fusion in7Li+144,152Sm reactions

Complete fusion cross sections for ${}^{7}$Li+${}^{144,152}$Sm reactions have been measured at energies around the Coulomb barrier by offline $\ensuremath{\gamma}$-counting technique. Measured cross sections for the above two reactions are found to be similar at energies well above the Coulomb barrier, however, at sub-barrier energies the cross sections for the ${}^{7}$Li+${}^{152}$Sm system are much higher compared to the ${}^{7}$Li+${}^{144}$Sm system, manifesting the effect of target deformation. Cross sections for the present reactions at above-barrier energies are found to be larger than previously measured reactions involving ${}^{6}$Li projectile with the same targets, possibly due to smaller breakup probability of ${}^{7}$Li than ${}^{6}$Li. Coupled-channels calculations show that the experimental fusion cross sections for both the systems are enhanced at subbarrier energies and suppressed at above-barrier energies compared to the respective one-dimensional barrier penetration model predictions. The calculations by different models show that the measured complete fusion cross sections at above-barrier energies are suppressed up to $\ensuremath{\sim}$25% compared to the theoretical predictions. It also reveals that a large part of the suppression could be due to inelastic and transfer coupling.

Synthesis, properties and phase transitions of pyrochlore- and fluorite-like Ln2RMO7 (Ln = Sm, Ho; R = Lu, Sc; M = Nb, Ta)

We have studied the new compounds with fluorite-like (Ho2RNbO7 (R=Lu, Sc)) and pyrochlore-like (Sm2ScTaO7) structure as potential oxide ion conductors. The phase formation process (from 1200 to 1600°C) and physical properties (electrical, thermo mechanical, and magnetic) for these compounds were investigated. Among the niobate materials the highest bulk conductivity is offered by the fluorite-like Ho2ScNbO7 synthesized at 1600°C: 3.8×10−5S/cm at 750°C, whereas in Sm system the highest bulk conductivity, 7.3×10−6S/cm at 750°C, is offered by the pyrochlore Sm2ScTaO7 synthesized at 1400°C. In Sm2ScTaO7 pyrochlore we have observed the first-order phase transformation at ∼650–700°C is related to rearrangement process in the oxygen sublattice of the pyrochlore structure containing B-site cations in different valence state and actually is absent in the defect fluorites.The two holmium niobates show Curie–Weiss paramagnetic behavior, with the prevalence of antiferromagnetic coupling. The magnetic susceptibility of Sm2ScTaO7 is a weak function of temperature, corresponding to Van Vleck paramagnetism.

Preparation of As–In–S:Sm thin films and a study of their properties

The study examines the physico-chemical properties of thin films of the As–In–S:Sm system. Thin amorphous films were prepared by thermal evaporation (TE) from two sources (As–In–S glass and metallic Sm) and by pulsed laser deposition (PLD). The films prepared with PLD contained more Sm and In than the TE films. The optical gap of the PLD films is lower than that of the TE films (Egopt=2.29eV for TE, Egopt=1.88eV for PLD), both are dependent on exposure of films and on their annealing. The as-deposited PLD films did not contain any separated As4S4 molecules; overstoichiometric arsenic was incorporated into the amorphous matrix. The index of refraction of the prepared PLD films (nћω→0=2.48) is higher than that of the TE films (nћω→0=2.35). The corresponding coefficient of the third order non-linear optical susceptibility (χ(3)) is also higher (PLD: 6.83×10−20m2/V2, TE: 4.02×10−20m2/V2). The structural changes induced by exposure and by annealing, determined by Raman spectroscopy, can be described through photochemical reactions (induced by exposure) and chemical reactions (induced by annealing). The strong luminescence bands were assigned to inner f–f electron transitions. The material is promising for a number of applications.

Genetic parameters for reproductive traits in female Nile tilapia (Oreochromis niloticus): I. Spawning success and time to spawn

Breeding programmes for Nile tilapia typically use nested mating designs with 2 females mated to 1 male to produce paternal half-sib families. This mating design can take up to 3months or longer to produce the desired number of half-sib family groups. Prolonged family production increases common environmental effects, and negatively affects estimation of genetic parameters. In this paper we investigated the hypothesis that prolonged family production is a consequence of selection for growth in Nile tilapia. We compare two mating systems: group mating with 7 males and 15 females (MM) and group mating with a single male and 10 females (SM), using females from generation 12 of the GIFT sub-strain kept at RIA-2, Vietnam. Spawning success was modelled as a threshold trait (SPAWN) using a linear repeatability animal model and a generalised logit linear repeatability model. All animals that spawned before 32days were labelled ‘spawn’ (1) and animals that did not spawn after 32days were considered as ‘no-spawn’ (0). We then changed the threshold and estimated heritability at each threshold point; e.g. with a threshold at 20days, all animals with ‘spawn’ records after 20days are considered ‘no-spawn’. Overall, the MM experiment yielded a higher proportion of successful spawn records than the SM experiment. However, in both experiments 85% of the successful spawns were produced within 20days. In the SM system, males frequently mated with more than one female during a mating period of 4days. Heritability estimates for SPAWN were 0.20 to 0.22 for linear model and 0.14–0.18 for logit model with thresholds from 20 to 32days. Estimates were consistent between linear and logit models. Estimates for ‘time to spawn’ were not different from zero (0.01±0.02). Genetic correlations of SPAWN with harvest weight ranged from 0.48 to 0.52 for thresholds of 20–32days. We conclude that Nile tilapia favour mating in groups and that spawning success as defined here is a heritable trait. Selection for harvest weight in GIFT should improve spawning success of Nile tilapia, provided the mating period is limited to 20–32days. To facilitate the rapid production of paternal half-sibs, we recommend using a group mating design with single males and multiple females in a single tank.

Difference in the stable isotopic fractionations of Ce, Nd, and Sm during adsorption on iron and manganese oxides and its interpretation based on their local structures

Many elements have become targets for studies of stable isotopic fractionation with the development of various analytical techniques. Although several chemical factors that control the isotopic fractionation of heavy elements have been proposed, it remains controversial which properties are most important for the isotopic fractionation of elements. In this study, the stable isotopic fractionation of neodymium (Nd) and samarium (Sm) during adsorption on ferrihydrite and δ-MnO2 was examined. This examination was combined with speciation analyses of these ions adsorbed on the solid phases by extended X-ray absorption fine structure (EXAFS) spectroscopy. Neodymium isotope ratios for Nd on ferrihydrite and δ-MnO2 systems were, on average, 0.166‰ and 0.410‰ heavier than those of the liquid phase, which correspond to mean isotopic fractionation factors between the liquid and solid phases (αLq–So) of Nd on ferrihydrite and δ-MnO2 of 0.999834 (2σ=±0.000048) and 0.999590 (2σ=±0.000106), respectively. Similarly, averaged Sm isotope ratios on ferrihydrite and δ-MnO2 were 0.206‰ and 0.424‰ heavier than those of the liquid phase and the corresponding αLq–So values were 0.999794 (±0.000041) and 0.999576 (±0.000134), respectively. These results indicate that the directions of isotopic fractionation in the Nd and Sm systems are in contrast with that recently found for Ce(III) systems despite the similar chemical characteristics of rare earth elements.EXAFS analyses suggest that the bond length of the first coordination sphere (REE–O bond) of Nd and Sm adsorbed on δ-MnO2 is shorter than that of their aqua ions, although this was not clear for the ferrihydrite systems. The shorter bond length relative to the aqua ion is indicative of a stronger bond, suggesting that the equilibrium isotopic fractionation for the Nd and Sm systems can be governed by bond strength as has often been discussed for isotopic fractionation in solid–water adsorption systems. Meanwhile, EXAFS analyses of the Ce/ferrihydrite system showed a distorted structure for the first coordination sphere that was not observed for Ce3+ aqua ions. Such distortion was also observed for La adsorption on ferrihydrite and δ-MnO2. In addition, previous studies have suggested a high stability of the hydrated state for La and Ce in terms of Gibbs free energy change. Thus, we suggest here that the difference in the stable isotopic fractionation for Ce (and predicted for La) vs. Nd and Sm can be explained by (i) the shorter bond lengths of adsorbed relative to dissolved species for Nd and Sm and (ii) the distorted structure of adsorbed Ce (and La) species and high stability of the aqua Ce ion.