A Colorimetric and Fluorescent Indicator for Hg<Superscript>2+</Superscript> Detection Based on Cinnamamide Group-Containing Rhodamine Derivative

A colorimetric and fluorescent indicator based on cinnamamide group-containing rhodamine derivative was synthesized for the detection of Hg²⁺. The rhodamine B and cinnamamide were connected via ethylenediamine as a bridging molecule through a condensation reaction to obtain a colorimetric and fluorescent indicator for the detection of Hg²⁺ in H₂O-EtOH (4:1, v/v). The indicator was excellent in the selectivity of Hg²⁺ and was almost unaffected by other common ions such as Na⁺, K⁺, Mg²⁺, Fe³⁺, Cu²⁺, Zn²⁺, Cr³⁺. The Hg²⁺-containing aqueous solution turned from colorless to red within 7 min after the addition of the indicator, and had an absorption peak at 564 nm in UV-vis, which implies a significant colorimetric phenomenon. Their characteristic peaks varied with the Hg²⁺ content, and they reached a linear relationship at low concentrations. The binding stoichiometry proved to be 1:1. The lowest detection limit was 4.1?×?10^?7 mol/L, ranging from acidic to neutral.     

Synthesis and Studies of Fluorescein Based Derivatives for their Optical Properties,Urease Inhibition and Molecular Docking

Herein, we design and synthesized new fluorescein based derivatives by insitu formation of fluorescein ester and further treated with corresponding hydrazide and amine to yield respective compounds i.e. FB1, FB2, FB3 and FB4. The spectral purity and characterization was done by using IR, NMR and Mass spectroscopies. The synthesized derivatives were examined for their photophysical properties by using variety of organic solvents and results were discussed in details. The structural diversity of synthesized compounds motivate us to evaluate these compounds for urease inhibition. The compound FB3 (IC₅₀?=?0.0456 μM) shows 100 fold more active against Jack bean urease than standard drug thiourea (IC₅₀?=?4.7455 μM). Other synthesized compounds showed potent activity. Free radical percentage scavenging assay further supported the capacity of compounds to urease inhibition. While, molecular docking simulations helps to examine the molecular interactions of active compounds FB1, FB2, FB3 and FB4 within the binding site of urease enzyme.     

Monitoring the Instant Creation of a New Fluorescent Signal for Evaluation of DNA Conformation Based on Intercalation Complex

Here we report the monitoring the instant creation of a new fluorescent signal (FS) aroused from a positively charged water-soluble fluorogenic probe, ethidium bromide (EtBr) in the presence of a radical initiator, ammonium persulfate (APS) and an accelerator, tetraethylmetilendiamine (TEMED) for evaluation of deoxyribonucleic acid (DNA) conformation. The results revealed that the occurred FS (λ_ex?=?430 nm; λ_max?=?525 nm) is a reduced form of EtBr (λ_ex?=?480 nm; λ_max?=?617 nm) and it is completely distinct from hydroethidine (λ_ex?=?350 nm; λ_max?=?430 nm), which is two-electron reduced form of EtBr. It was noticed that EtBr was reduced to a new FS during the polymerization of N, N dimethyacrylamide (DMAA) too, at 25 °C in the presence of APS and TEMED or at 55 °C with only APS, and the rate of formation of FS was increased upon treatment time. The effect of nanoclays such as Laponite XLG® and Laponite XLS®, which provide a protective environment for DNA in nature, were also investigated through the reduction process of EtBr in the absence and presence of a water soluble monomer DMAA. We demonstrated that DNA conformation might be evaluated by monitoring FS effectuated during the reduction of EtBr in the presence of nanoclays having positively and negatively charged surfaces. Protective property of DNA against the formation of reduced product was elucidated by carrying out the polymerization at 55 °C. The results revealed that the monitoring of formation of FS in the presence of radical initiator could lead to elucidate the conformation of DNA upon formation of intercalator complex.     

Inhomogeneous Double Optical Gating of High-Intensity Isolated Attosecond Pulse Generation in Crossed Metal Nanostructures

We propose and investigate an effective method for obtaining high-energy and high-intensity isolated attosecond pulses (IAPs) using the inhomogeneous double optical gating (DOG) technology in specifically designed metal nanostructures. First, using the homogeneous mid-infrared DOG technology modulated by a linearly near-infrared field, we obtain a harmonic yield of 2.5 orders of magnitudes higher than that from the single polarization gating (PG) technology. Further, introducing the crossed metal nanostructures along the driven and gating components, we can extend not only the harmonic cutoff but also enhance the harmonic yield attributed to the plasmonic field enhancement near the vicinity of metal nanostructures. As a result, we find a single harmonic plateau with smaller modulations. The supercontinuum is not very sensitive to the pulse duration of the near-infrared field, and the harmonic yields can be further enhanced with increase in the pulse intensity of the near-infrared field, showing a 108 eV supercontinuum with an intensity enhancement of 4 orders of magnitudes. Finally, by superposing the selected harmonics from the inhomogeneous DOG scheme, we obtain a 33 as SAP with an intensity increase of 4 orders of magnitudes.     

Quantum Discord for Information Transmission Using Coherent States

We suggest theoretically the possibility to transmit information through a decohering quantum channel employing Glauber’s coherent states. In fact, we study the dynamics of quantum correlations of two-mode entangled bipartite coherent states in the presence of the amplitude damping effect. In addition, we examine the quantum correlations based on quantum discord, which is a powerful key source in quantum information processing.     

Using Laser Measuring and SFM Algorithm for Fast 3D Reconstruction of Objects

Effective measurement of the reflective or transparent surface of an object has always been a disadvantage in laser scanning modeling. We propose a fast and complete three-dimensional (3D) reconstruction method for small static objects using laser scanning and the structure from motion (SFM) algorithm. Meanwhile, a complete reconstruction workflow is designed and a multi-angle 3d reconstruction system is set up. To generate the complete point cloud model of the object, the SFM algorithm is used to reconstruct the surface part of the object, the data for which cannot be obtained by the laser measuring instrument. The experimental results show that this method not only improves the speed, accuracy, integrity, and visual effect of 3D reconstruction of small objects, but also extends the scope of 3D reconstruction of laser measurement.     

On the Small Mass Limit of Quantum Brownian Motion with Inhomogeneous Damping and Diffusion

We study the small mass limit (or: the Smoluchowski–Kramers limit) of a class of quantum Brownian motions with inhomogeneous damping and diffusion. For Ohmic bath spectral density with a Lorentz–Drude cutoff, we derive the Heisenberg–Langevin equations for the particle’s observables using a quantum stochastic calculus approach. We set the mass of the particle to equal \(m = m_{0} \epsilon \), the reduced Planck constant to equal \(\hbar = \epsilon \) and the cutoff frequency to equal \(\varLambda = E_{\varLambda }/\epsilon \), where \(m_0\) and \(E_{\varLambda }\) are positive constants, so that the particle’s de Broglie wavelength and the largest energy scale of the bath are fixed as \(\epsilon \rightarrow 0\). We study the limit as \(\epsilon \rightarrow 0\) of the rescaled model and derive a limiting equation for the (slow) particle’s position variable. We find that the limiting equation contains several drift correction terms, the quantum noise-induced drifts, including terms of purely quantum nature, with no classical counterparts.     

Replica Bounds by Combinatorial Interpolation for Diluted Spin Systems

In two papers Franz et al. proved bounds for the free energy of diluted random constraints satisfaction problems, for a Poisson degree distribution (Franz and Leone in J Stat Phys 111(3–4):535–564, 2003) and a general distribution (Franz et al. in J Phys A 36(43), 10967, 2003). Panchenko and Talagrand (Probab Theo Relat Fields 130(3):319–336, 2004) simplified the proof and generalized the result of Franz and Leone (J Stat Phys 111(3–4):535–564, 2003) for the Poisson case. We provide a new proof for the general degree distribution case and as a corollary, we obtain new bounds for the size of the largest independent set (also known as hard core model) in a large random regular graph. Our proof uses a combinatorial interpolation based on biased random walks (Salez in Combin Probab Comput 25(03):436–447, 2016) and allows to bypass the arguments in Franz et al. (J Phys A 36(43):10967, 2003) based on the study of the Sherrington–Kirkpatrick (SK) model.     

Stochastic Averaging Principle for Spatial Birth-and-Death Evolutions in the Continuum

We study a spatial birth-and-death process on the phase space of locally finite configurations \({\varGamma }^+ \times {\varGamma }^-\) over \({\mathbb {R}}^d\). Dynamics is described by an non-equilibrium evolution of states obtained from the Fokker-Planck equation and associated with the Markov operator \(L^+(\gamma ^-) + \frac{1}{\varepsilon }L^-\), \(\varepsilon > 0\). Here \(L^-\) describes the environment process on \({\varGamma }^-\) and \(L^+(\gamma ^-)\) describes the system process on \({\varGamma }^+\), where \(\gamma ^-\) indicates that the corresponding birth-and-death rates depend on another locally finite configuration \(\gamma ^- \in {\varGamma }^-\). We prove that, for a certain class of birth-and-death rates, the corresponding Fokker-Planck equation is well-posed, i.e. there exists a unique evolution of states \(\mu _t^{\varepsilon }\) on \({\varGamma }^+ \times {\varGamma }^-\). Moreover, we give a sufficient condition such that the environment is ergodic with exponential rate. Let \(\mu _{\mathrm {inv}}\) be the invariant measure for the environment process on \({\varGamma }^-\). In the main part of this work we establish the stochastic averaging principle, i.e. we prove that the marginal of \(\mu _t^{\varepsilon }\) onto \({\varGamma }^+\) converges weakly to an evolution of states on \({\varGamma }^+\) associated with the averaged Markov birth-and-death operator \({\overline{L}} = \int _{{\varGamma }^-}L^+(\gamma ^-)d \mu _{\mathrm {inv}}(\gamma ^-)\).     

Motion of a Rigid Body in a Special Lorentz Gas: Loss of Memory Effect

Linear motion of a rigid body in a special kind of Lorentz gas is mathematically analyzed. The rigid body moves against gas drag according to Newton’s equation. The gas model is a special Lorentz gas consisting of gas molecules and background obstacles, which was introduced in Tsuji and Aoki (J Stat Phys 146:620–645, 2012). The specular boundary condition is imposed on the resulting kinetic equation. This study complements the numerical study by Tsuji and Aoki cited above—although the setting in this paper is slightly different from theirs, qualitatively the same asymptotic behavior is proved: The velocity V(t) of the rigid body decays exponentially if the obstacles undergo thermal motion; if the obstacles are motionless, then the velocity V(t) decays algebraically with a rate \(t^{-\,5}\) independent of the spatial dimension. This demonstrates the idea that interaction of the molecules with the background obstacles destroys the memory effect due to recollision.