Rm Ag Research Articles

Pure green emission self-crystallization CsPbBr3 quantum dot glass with Ag+ doping for stable light-emitting devices.

Recently, cesium lead bromide perovskite glass has been recognized as a potential material to fabricate green light emission devices because of their high stability and excellent optical performance. However, the low photoluminescence efficiency and poor color purity ($\lt\! 525\,\,{\rm nm}$) of ${{\rm CsPbBr}_3}$ quantum dot (QD) glass restricts its practical application. In this work, self-crystallization ${{\rm CsPbBr}_3}$ QD glasses are successfully prepared via the melt quenching method, and the photoluminescence efficiency increases 10-fold compared with regular thermal treatment ${{\rm CsPbBr}_3}$ QD glass without ${\rm Ag}^+$ doping. The green light-emitting devices based on bulk self-crystallization ${{\rm CsPbBr}_3}$ QD glass with 0.4 mol.% ${\rm Ag}^+$ doping achieves a luminescence efficiency of 20.85 lm/W with a CIE (0.2084, 0.6026) under a 20 mA driving current. The present results provide new, to the best of our knowledge, insight into the application of ${{\rm CsPbBr}_3}$ QD glass in the optoelectronic field.

The VLT LBG redshift survey – VI. Mapping H i in the proximity of z ∼ 3 LBGs with X-Shooter

We present an analysis of the spatial distribution of gas and galaxies using new X-Shooter observations of $z\sim3-4$ quasars. Adding the X-Shooter data to an existing dataset of high resolution quasar spectroscopy, we use a total sample of 29 quasars alongside $\sim1700$ Lyman Break Galaxies in the redshift range $2<z<3.5$. Analysing the Ly$\alpha$ forest auto-correlation function using the full quasar sample, we find $s_0=0.081\pm0.006h^{-1}$Mpc. We then investigate the clustering and dynamics of Ly$\alpha$ forest absorbers around $z\sim3$ LBGs. From the redshift-space cross-correlation, we find $s_0=0.27\pm0.14h^{-1}$Mpc, with power-law slope $\gamma=1.1\pm0.2$. We make a first analysis of the dependence of this clustering length on absorber strength based on cuts in the sightline transmitted flux, finding a clear preference for stronger absorption features to be more strongly clustered around the galaxy population than weaker absorption features. Further, we calculate the projected correlation function, finding $r_0=0.24\pm0.04h^{-1}$Mpc (assuming a fixed slope $\gamma=1.1$). Taking this as the underlying real-space clustering, we fit the 2D cross-correlation function with a dynamical model incorporating the infall parameter and the peculiar velocity, finding $\beta_{\rm F}=1.02\pm0.22$ and $240\pm60$ km s$^{-1}$ respectively. This result shows a significant detection of gas infall relative to the galaxy population, whilst the measured velocity dispersion is consistent with the velocity uncertainties on the galaxy redshifts. We evaluate the Cauchy-Schwarz inequality between the galaxy-galaxy, absorber-absorber, and galaxy-absorber correlation functions, finding a result significantly less than unity: $\xi_{\rm ag}^2/(\xi_{\rm gg}\xi_{\rm aa})=0.25\pm0.14$, implying that galaxies and Ly$\alpha$ absorbers do not linearly trace the underlying dark matter distribution in the same way.

The annihilating-submodule graph of modules over commutative rings II

Let M be a module over a commutative ring R. The annihilating-submodule graph of M, denoted by AG(M), is a simple graph in which a non-zero submodule N of M is a vertex if and only if there exists a non-zero proper submodule K of M such that N K = (0), where N K, the product of N and K, is denoted by (N : M)(K : M)M and two distinct vertices N and K are adjacent if and only if N K = (0). This graph is a submodule version of the annihilating-ideal graph. We prove that if AG(M) is a tree, then either AG(M) is a star graph or a path of order 4 and in the latter case $${M\cong F \times S}$$ , where F is a simple module and S is a module with a unique non-trivial submodule. Moreover, we prove that if M is a cyclic module with at least three minimal prime submodules, then gr(AG(M)) = 3 and for every cyclic module M, $${cl({\rm AG}(M)) \geq |{\rm Min}(M)|}$$ .

Communication: Global minimum search of Ag₁₀⁺ with molecular beam optical spectroscopy.

The present study is focused on the optical properties of the Ag₁₀⁺ cluster in the photon energy range ℏω = 1.9-4.4 eV. Absorption spectra are recorded by longitudinal molecular beam depletion spectroscopy and compared to optical response calculations using time-dependent density functional theory. Several cluster isomers obtained by the new pool-based parallel implementation of the Birmingham Cluster Genetic Algorithm, coupled with density functional theory, are used in excited state calculations. The experimental observations, together with additional simulations of ion mobilities for the several geometries found within this work using different models, clearly identify the ground state isomer of Ag₁₀⁺ to be composed of two orthogonal interpenetrating pentagonal bipyramids, having overall D(2d) symmetry.

Recrystallization and ${\rm Ag}_{3}{\rm Sn}$ Particle Redistribution During Thermomechanical Treatment of Bulk Sn–Ag–Cu Solder Alloys

Sn-Ag-Cu (SAC) solders are susceptible to appreciable microstructural coarsening during storage or service. This results in evolution of joint properties over time and thereby influences the long-term reliability of microelectronic packages. Accurate reliability prediction of SAC solders requires prediction of microstructural evolution during service. Microstructure evolution in two SAC solder alloys, such as, Sn-3.0Ag-0.5Cu (SAC 305) and Sn-1.0Ag-0.5 Cu (SAC 105), under different thermomechanical excursions, including isothermal aging at 150°C and thermomechanical cycling (TMC) was studied. In general, between 200 and 600 cycles during TMC, recrystallization of the Sn matrix was observed, along with redistribution of Ag3Sn particles because of dissolution and reprecipitation. These latter effects have not been reported before. It was also observed that the Sn grains recrystallized near precipitate clusters in eutectic channels during extended isothermal aging. The relative orientation of Sn grains in proeutectic colonies did not change during isothermal aging.

Equilibrium Model for Cooperative Activation of Muscle by Calcium

The purpose of this study is to model the cooperative activation of muscle. Current models for calcium activation are based on three positions of tropomyosin, i.e., troponin-dependent (B), central (C), and myosin-dependent (M). Regulation of molluscan muscle, which lacks troponin, may be the basis for cooperative activation of all filamentous myosin systems. However, fitting actual calcium-dependent isometric force (F-Ca) data has been difficult to achieve for all muscle and, among existing models, none has been shown to be compatible with muscle that lacks troponin. We describe a mass action mechanism for cooperative activation that involves only Positions C and M. We show that our model fits F-Ca of scallop striated adductor muscle (RM Simmons and AG Szent-Gyorgyi, 1985, J. Physiol. 358: 47-64). Furthermore, given troponin that regulates simply by binding actin in Position B, we show that this same model will fit F-Ca of vertebrate striated muscle regulated by both native and mutant forms of troponin (MA Regnier et al., 2002, J. Physiol. 15: 485-497). Our model also fits paired myosin binding and thin filament activation data (KM Trybus and EW Taylor, 1980, Proc. Natl. Acad. Sci 77: 7209-7213). The results suggest that myosin binding couples energetically to a conformational change in tropomyosin that propagates in position M. Expansion of segments of tropomyosin in position M promotes the association of uncoupled myosin, which stabilizes one coupled myosin for each segment. Exponential growth of segments by this feed-forward mechanism is limited by the finite supply of tropomyosin in Position C, which can be controlled by troponin in Position B. A derivation and application to thin and thick filament regulation may be found on-line (www.westga.edu/STEMresearch). This work was supported by NSF grant MCB-0508203 (HGZ).

Influence of the Si Substrate on the Transport and Magnetotransport Properties of Nanostructured Fe-Ag Thin Films

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A systematic study of electrical and magnetic transport properties of <formula formulatype="inline"><tex Notation="TeX">${\rm Fe}_{x}{\rm Ag}_{100-x}$</tex> </formula> <formula formulatype="inline"><tex Notation="TeX">$(50≪x≪55)$</tex> </formula> thin films deposited by both sputtering and pulsed laser ablation onto two <formula formulatype="inline"><tex Notation="TeX">$p$</tex></formula>-type Si substrates with different resistivities is reported in this work. Resistance, magnetoresistance and Hall effect were measured in the temperature range 75–350 K. Magnetization was measured in the temperature range 5–300 K, showing no appreciable differences for samples deposited onto one substrate or the other. A near room temperature transition in the resistance has been observed only for samples deposited onto the lower resistance substrate. Before this transition, the results obtained agree well with the conduction being almost completely confined to the metallic film, but after the transition, apparently most of the carriers change to the substrate. This is corroborated by the positive magnetoresistance and the change in the sign of the carriers indicated by the Hall measurements after the transition. The experimental results agree well with a three layer model that includes an interface whose resistance increases exponentially with decreasing temperature. </para>

Microstructure, topology and X-ray diffraction in Ag-metal reinforced polymer of polyvinyl alcohol of thin laminates

A polymer composite of Ag-metal reinforced polyvinyl alcohol (PVA) is synthesized in shape of thin laminates of 200–300 μm thickness. The process involves a chemical Ag+ dispersion in PVA and in-situ \({\rm Ag}^{+} \to {\rm Ag}\) reduction-reaction with active PVA molecules under hot conditions (with stirring) in water at 60–70°C temperature. The product results in a metal Ag-polymer complex dispersed in the solution. After evaporating part of water, a derived viscous solution is casted (in hot conditions) in shape of a thin laminate in a glass mould. In addition to chemical reducer, active OH-groups (free from H-bonding) in PVA molecules of refreshed surfaces act as head groups to adsorb Ag+ and drive a directional \({\rm Ag}^{+} \to {\rm Ag}\) growth. Short fibrils of Ag-metal thus occur in reaction over the PVA molecules. Casting thin laminates from a liquid sample Ag-PVA allows the fibrils (also the polymer molecules) to align along the surface. Selected Ag-contents up to 5.0 wt.% in Ag-PVA laminates are studied in terms of scanning electron micrograph, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Average size, morphology and aspect ratio (ϕ) vary in Ag-metal depending on the Ag-content. As long Ag-metal fibrils as 2–5 μm, ϕ=35, occur in a sample of 2.0 wt.% Ag. The Ag-metal reflects in two characteristic 3d5/2 and 3d/3/2 XPS bands of 368.3 and 374.1 eV respectively.

The System HCl + NdCl3 + H2O from 5 to 55 ∘C: A Study of Harned's Rule

The activity coefficients of HCl (γA) in aqueous mixtures of HCl and NdCl3 were determined by the electromotive-force (emf) measurement of cells without liquid junctions of the type: $${\rm Pt},{\rm H}_{2} ({\rm g},1 {\rm atm})|{\rm HCl}(m_{\rm A}) + {\rm NdCl}_{3} (m_{\rm B}) + {\rm H}_{2} {\rm O}|{\rm AgCl},{\rm Ag}$$ (A)

Continuous-wave Doppler-free two-photon spectroscopy of the $\mathsf{4d^{10}5s}$ $\mathsf{^{2}}$S $\mathsf{_{1/2}\rightarrow 4d^{9}5s^{2}}$ $\mathsf{^{2}}$D $\mathsf{_{3/2}}$ transition in atomic silver

The frequencies of the hyperfine components of the transition \(4d^{10}5s ^{2}S_{1/2} \rightarrow 4d^{9}5s^{2}\) 2 D 3/2 in 107Ag and 109Ag have been determined using Doppler-free two-photon laser spectroscopy of a thermal atomic beam and heterodyne calibration with respect to a molecular iodine line 111R(18-1) near 520 THz. For the centre of gravity of a mixture of natural abundance, we deduce the value 1 040 706 327(3) MHz. For the isotope shift, we obtain \(\nu(^{109}{\rm Ag})-\nu(^{107}{\rm Ag}) = + 599.6(2)\) MHz. We find the magnetic hyperfine splitting constants of the excited state to be A(107Ag (2D 3/2)) = -315.9(2) MHz and A(109Ag (2D 3/2)) = -363.3(2) MHz, an order of magnitude improvement over previous authors [W. Fischer et al. , Z. Phys. 238, 249 (1970)].

The geometry of Grauert tubes and complexification of symmetric spaces

We consider complexifications of Riemannian symmetric spaces $X$ of nonpositive curvature. We show that the maximal Grauert domain of $X$ is biholomorphic to a maximal connected extension $\Omega\sb {{\rm AG}}$ of $X=G/K\subset G\sb {\mathbb {C}}/K\sb {\mathbb {C}}$ on which $G$ acts properly, a domain first studied by D. Akhiezer and S. Gindikin [1]. We determine when such domains are rigid, that is, when ${\rm Aut}\sb {\mathbb {C}}(\Omega\sb {{\rm AG}}=G$ and when it is not (when \Omega\sb {{\rm AG}}$ has hidden symmetries). We further compute the $G$-invariant plurisubharmonic functions on $\Omega\sb {{\rm AG}}$ and related domains in terms of Weyl group invariant strictly convex functions on a $W$-invariant convex neighborhood of $0\in \mathfrak {a}$. This generalizes previous results of M. Lassalle [25] and others. Similar results have also been proven recently by Gindikin and B. Krotz [8] and by Krotz and R. Stanton [24].

Fluctuations, response and aging dynamics in a simple glass-forming liquid out of equilibrium

By means of molecular dynamics computer simulations we investigate the out of equilibrium relaxation dynamics of a simple glass former, a binary Lennard-Jones system, after a quench to low temperatures. We study both one time quantities and two-times correlation functions. Two-times correlation functions show a strong time and waiting time $t_w$ dependence. For large $t_w$ and times corresponding to the early $\beta$-relaxation regime the correlators approach the Edwards-Anderson value by means of a power-law in time. at long times $\tau$ the correlation functions can be expressed as $C_{\rm AG}(h(t_w+\tau)/h(t_w))$ and compute the function $h(t)$. This function is found to show a $t$-dependence which is a bit stronger than a logarithm and to depend on the observable considered. Finally we discuss our measurements of the time dependent response function. We find that at long times the correlation functions and the response are not related by the usual fluctuation dissipation theorem but that this relation is similar to the one found for spin glasses with one step replica symmetry breaking.

Electron Spin Resonance of γ-Irradiated Salts of Diethyl Phosphoric Acid

The ${\rm Mg}^{2+}, {\rm K}^{+}, {\rm Zn}^{2+}, {\rm Ba}^{2+}, {\rm Co}^{2+}, {\rm Ag}^{+}$, and Cd2+ salts of diethyl phosphoric acid have been γ-irradiated and observed by ESR in the temperature range between 77 and 300°K. The yield of the ${\rm CH}_{3}\dot{{\rm C}}{\rm HOP}({\rm O})_{2}{\rm OC}_{2}{\rm H}{}_{5}{}^{-}$ radical is relatively independent of the associated cation, whereas formation of the ${\rm CH}_{3}\dot{{\rm C}}{\rm H}_{2}$ and ${\rm C}_{2}{\rm H}_{5}{\rm O}\dot{{\rm P}}{\rm O}{}_{2}{}^{-}$ radicals is depressed, or absent, in the ${\rm Co}^{2+},{\rm Ag}^{+}$, and Cd2+ salts. It is concluded that the ethyl and ethylphosphite radicals are formed by dissociative electron attachment and that formation of ${\rm CH}_{3}\dot{{\rm C}}{\rm HOP}({\rm O})_{2}{\rm OC}_{2}{\rm H}{}_{5}{}^{-}$ is independent of electron addition.

Chemistry of the Hydrated Electron in Oxygen-Free Solutions of Amino Acids, Peptides, and Related Compounds

In extending previous studies on the radiation-induced deamination of the simpler α-amino acids in oxygen-free solution, it has been found that reductive deamination by the hydrated electron, ${\rm e}_{{\rm aq}}^{-}$ , is not confined to the free amino acid configuration. The dipeptides, tripeptides, and other derivatives of glycine, for example, are found to react with ${\rm e}_{{\rm aq}}^{-}$ (essentially quantitatively) to cleave the N-C bond of the primary amino group. Radiolysis studies of variously substituted amino compounds in solutions containing second solutes which are specific scavengers of H, OH in the one case and of ${\rm e}_{{\rm ag}}^{-}$ in the other indicates that reductive deamination by ${\rm e}_{{\rm aq}}^{-}$ requires an unsaturated function at the carbon position α to the amino group. It is suggested that ${\rm e}_{{\rm aq}}^{-}$ adds to this function and that N-C cleavage then e...