A numerical study on drop formation of viscoelastic liquids using a nonlinear constitutive equation

In this paper, a numerical solution for viscoelastic drop formation from a nozzle into an ambient gas is presented. A volume of fluid (VOF) method is used to predict the formation and break-up process of viscoelastic drop. Here, Giesekus model is used as the constitutive equation. The major features of the phenomenon, such as instantaneous drop length, limiting length of a drop at breakup, minimum drop radius and the volume of the primary drop is determined for a range of the parameter space spanned by the appropriate dimensionless groups. The results reveal that enhancing the mobility factor, Wiessenberg number, and viscosity ratio causes a noticeable decrease in limiting drop length and a small decrease on the primary drop volume. Also, the increasing of gravitational bond number and capillary number causes the limiting drop length increases while the primary drop volume is reduced.     

Effect of bending anisotropy on the 3D conformation of short DNA loops

The equilibrium three dimensional shape of relatively short loops of DNA is studied using an elastic model that takes into account anisotropy in bending rigidities. Using a reasonable estimate for the anisotropy, it is found that cyclized DNA with lengths that are not integer multiples of the pitch take on nontrivial shapes that involve bending out of planes and formation of kinks. The effect of sequence inhomogeneity on the shape of DNA is addressed, and shown to enhance the geometrical features. These findings could shed some light on the role of DNA conformation in protein-DNA interactions.     

Highly Stable Lithium Metal Anode Interface via Molecular Layer Deposition Zircone Coatings for Long Life Next‐Generation Battery Systems

Herein, molecular layer deposition is used to form a nanoscale “zircone” protective layer on Li metal to achieve stable and long life Li metal anodes. The zircone‐coated Li metal shows enhanced air stability, electrochemical performance and high rate capability in symmetrical cell testing. Moreover, as a proof of concept, the protected Li anode is used in a next‐generation Li‐O₂ battery system and is shown to extend the lifetime by over 10‐fold compared to the batteries with untreated Li metal. Furthermore, in‐situ synchrotron X‐ray absorption spectroscopy is used for the first time to study an artificial SEI on Li metal, revealing the electrochemical stability and lithiation of the zircone film. This work exemplifies significant progress towards the development and understanding of MLD thin films for high performance next‐generation batteries.     

Water‐Mediated Synthesis of a Superionic Halide Solid Electrolyte

To promote the development of solid‐state batteries, polymer‐, oxide‐, and sulfide‐based solid‐state electrolytes (SSEs) have been extensively investigated. However, the disadvantages of these SSEs, such as high‐temperature sintering of oxides, air instability of sulfides, and narrow electrochemical windows of polymers electrolytes, significantly hinder their practical application. Therefore, developing SSEs that have a high ionic conductivity (>10^?3 S cm^?1), good air stability, wide electrochemical window, excellent electrode interface stability, low‐cost mass production is required. Herein we report a halide Li⁺ superionic conductor, Li₃InCl₆, that can be synthesized in water. Most importantly, the as‐synthesized Li₃InCl₆ shows a high ionic conductivity of 2.04×10^?3 S cm^?1 at 25 °C. Furthermore, the ionic conductivity can be recovered after dissolution in water. Combined with a LiNi_0.8Co_0.1Mn_0.1O₂ cathode, the solid‐state Li battery shows good cycling stability.     

Determination of Salbutamol, Amikacin and Paromomycin Sulfate by a Novel Sulfate Polymeric Membrane Sensor Based on 2,6-diphenyl 4-(4-methoxyphenyl) pyrylium perchlorate

A novel sulfate polymeric membrane sensor based on 2,6-diphenyl 4-(4-methoxyphenyl) pyrylium perchlorate (DMPP) as a sensing material is presented. The electrode displays a very low detection limit (4.0×10^–7M) and wide working concentration range (8.0×10^–7–1.0×10^–1M). The sensor shows remarkable selectivity toward sulfate over most common organic and inorganic anions, including chloride, acetate, nitrate, nitrite, bromide, iodide, thiocyanate, phosphate, fluoride, sulfite, hydrogen sulfite, hydrogen carbonate, citrate, tartarate and oxalate. The sensor reveals a Nernstian behavior (slope of –29.7±0.5mV per decade) in a wide pH range (3.0–9.5). The proposed sensor shows a short response time over the entire working range (15s) and was successfully applied to the direct determination of salbutamol, amikacin and paromomycin sulfate.     

Ion recognition: application of symmetric and asymmetric schiff bases and their complexes for the fabrication of cationic and anionic membrane sensors to determine ions in real samples

Schiff base compounds refer to the branch of supra-molecules and can be used as sensing material in the construction of potentiometric ion selective electrodes (ISEs). This relatively modern field has been subject to extensive research in the period of 1999-2007 when more than 100 ISEs employing Schiff bases were constructed. The quantitative high-throughput detection of 29 cations and 7 anions has been demonstrated in various scientific branches, such as biomedicine, pharmacy, biochemistry, pharmacology, environmental chemistry, food technology, and agriculture. This review discusses Schiff base compounds and their applications in the design and development of ion selective sensors and microsensors.     

Radical‐Cation Dimerization Overwhelms Inclusion in [n]Pseudorotaxanes

Suppression of the dimerization of the viologen radical cation by cucurbit[7]uril ( CB7 ) in water is a well‐known phenomenon. Herein, two counter‐examples are presented. Two viologen‐containing thread molecules were designed, synthesized, and thoroughly characterized by ¹H DOSY NMR spectrometry, UV/Vis absorption spectrophotometry, square‐wave voltammetry, and chronocoulometry: BV ⁴⁺, which contains two viologen subunits, and HV ¹²⁺, which contains six. In both threads, the viologen subunits are covalently bonded to a hexavalent phosphazene core. The corresponding [3]‐ and [7]pseudorotaxanes that form on complexation with CB7 , that is, BV ⁴⁺?( CB 7)₂ and HV ¹²⁺?( CB 7)₆, were also analyzed. The properties of two monomeric control threads, namely, methyl viologen ( MV ²⁺) and benzyl methyl viologen ( BMV ²⁺), as well as their [2]pseudorotaxane complexes with CB7 ( MV ²⁺? CB7 and BMV ²⁺? CB7 ) were also investigated. As expected, the control pseudorotaxanes remained intact after one‐electron reduction of their viologen‐recognition stations. In contrast, analogous reduction of BV ⁴⁺?( CB 7)₂ and HV ¹²⁺?( CB 7)₆ led to host–guest decomplexation and release of the free threads BV ^{2( . +)} and HV ^{6( . +)}, respectively. ¹H DOSY NMR spectrometric and chronocoulometric measurements showed that BV ^{2( . +)} and HV ^{6( . +)} have larger diffusion coefficients than the corresponding [3]‐ and [7]pseudorotaxanes, and UV/Vis absorption studies provided evidence for intramolecular radical‐cation dimerization. These results demonstrate that radical‐cation dimerization, a relatively weak interaction, can be used as a driving force in novel molecular switches.     

Electrocatalytic oxidation of formaldehyde on Ni/Poly(N,N-Dimethylaniline) (sodium dodecylsulfate) modified carbon paste electrode in alkaline medium

In this work, an aqueous solution of sodium dodecylsulfate (SDS) surfactant is used as an additive for electropolymerization of N,N-dimethylaniline (DMA) onto carbon paste electrode (CPE), which is investigated as a novel matrix for deposition of nickel. The electrochemical oxidation of formaldehyde is studied at the surface of this modified electrode. The electrooxidation of formaldehyde was found to be more efficient on CPE modified with Ni/Poly(N,N-Dimethylaniline) (SDS), Ni/PDMA (SDS), than deposition Ni on CPE in alkaline solution. The electrochemical behavior and electrocatalytic activity of the electrode were studied using cyclic voltammetry and chronomethods studies. Also, the transfer second-order rate constant (k = 5.5 × 10³ cm³ mol^?1 s^?1) between formaldehyde and nickel hydroxide was calculated. Moreover, in order to optimize of electrode and variables for efficient performance of Ni/PDMA (SDS)/CPE towards formaldehyde oxidations, the effect of various parameters such as number of potential cycles for preparation of polymer, nickel and formaldehyde concentration and accumulation time have been investigated.     

13C-sialic acid labeling of glycans on glycoproteins using ST6Gal-I

Glycans that are either N-linked to asparagine or O-linked to serine or threonine are the hallmark of glycoproteins, a class of protein that dominates the mammalian proteome. These glycans perform important functions in cells and in some cases are required for protein activity. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for studying glycan structure and interactions, particularly in a form that exploits heteronuclei such as 13C. Here an approach is presented that that uses alpha-2,6-sialyltransferase (ST6Gal-I) to enzymatically add 13C-N-acetylneuraminic acid (NeuAc or sialic acid) to glycoproteins after their preparation using nonbacterial hosts. ST6Gal-I is itself a glycoprotein, and in this initial application, labeling of its own glycans and observation of these glycans by NMR are illustrated. The catalytic domain from rat ST6Gal-I was expressed in mammalian HEK293 cells. The glycans from the two glycosylation sites were analyzed with mass spectrometry and found to contain sialylated biantennary structures. The isotopic labeling approach involved removal of the native NeuAc residues from ST6Gal-I with neuraminidase, separation of the neuramindase with a lectin affinity column, and addition of synthesized 13C-CMP-NeuAc to the desialylated ST6Gal-I. Chemical shift dispersion due to the various 13C-NeuAc adducts on ST6Gal-I was observed in a 3D experiment correlating 1H-13C3-13C2 atoms of the sugar ring.     

Electro-organic synthesis and characterization of new dihydroxybenzene dinitrile derivatives with fluorescent properties

Novel fluorescent molecules were synthesized by designing an environmentally friendly method involving the bulk electrolysis technique. This electrochemical treatment process helps protect the environment by minimizing the toxic waste component of effluent. The electrochemical oxidation of 3,6-dihydroxybenzene-1,2-dinitrile (DBD) in the presence of benzenesulfinic acids was studied in an aqueous solution (H(2)O : AN, 90 : 10), which included an acetate buffer (pH=5.0). This research utilized a variety of experimental techniques, including cyclic voltammetry, controlled-potential electrolysis as well as spectroscopic identification of compounds produced as products. In addition, our fluorescent studies offered results in line with existing findings. At the wavelength of 205 nm, DBD and compound (6) were excited and their fluorescent emissions were monitored.