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Highlights: [•] Improvement of the direct quantification with analytical pyrolysis. [•] Optimization of the chromatographic parameters after pyrolysis of cationic starch. [•] Quantification of cationic starches in cellulose matrixes. [•] Validation of the cationic starch quantification in paper samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • GQD-DDT and GQD-MPA was synthesized using novel hydrothermal protocol. • GQD-DDT and GQD-MPA was used for the identification of cations using colorimetric and spectrophotometric assay. • GQD-DDT and GQD-MPA have well activity for ion sensing in aqueous solution. This study describes the synthesis of various types of thiolated-graphene quantum dots (GQDs) for the simultaneous multi-sensing of heavy metal ions using one-droplet microfluidic paper-based analytical devices (OD- µ PADs). For the first time, functionalized GQDs were synthesized and stabilized on the surface of hydrophobic fiber-glass with simple manufacturing and assembly strategy towards colorimetric chemosensing of ions including iron, copper, cobalt, mercury, chrome, manganese, and nickel. For this purpose, GQDs are functionalized by various organic species including cysteamine, decanethiol, and mercaptopropionic acid (MPA) towards specific electrostatic interaction with metal ions of Fe (II), Cu (II), Co(II), Hg (II), Mn (II), and Ni (II). Therefore, an innovative GQDs-based miniaturized chemo-system was proposed for the environmental analysis. Additionally, the results were confirmed using fluorescence spectrometry as an optical detection method. Finally, this simple and efficient colorimetric platform was used for facile metal ions detection in human urine models, and environmental fluids, which can provide a commercial device for sensing contaminants by non-professional users in biomedical/environmental mixture. As an economical technique, this platform presents a "mix-and-sense" system without dye (as a side substance) or chemical treatments. The low instrumental requirements, the color uniformity, and the disposability of OD- μ PADs approve the commercial application of the engineered ion-chemosensor. [ABSTRACT FROM AUTHOR]

Abstract: This study examines and quantifies the effect of cationic polyacrylamide (CPAM) dissolution kinetics and charge density on the adsorption and aggregation state of gold nanoparticles (AuNPs) on paper and the resulting Surface Enhanced Raman Scattering (SERS) performance. Dissolution kinetics of CPAM of different charge density was studied by monitoring their viscosity and hydrodynamic diameter over regular intervals of time. It was found that the degree of dissolution of CPAM greatly affected the surface coverage and aggregation of AuNPs on the CPAM pre-adsorbed paper substrate and their SERS reproducibility. CPAM of higher charge density dissolves faster and produced a more uniform aggregation and higher surface coverage of AuNPs on paper for a higher and more reproducible Raman EF. Understanding the CPAM dissolution process enables the optimization of SERS performance of the AuNPs-paper as a bio-diagnostic platform. [Copyright &y& Elsevier]

Abstract: Large numbers of soil samples are routinely analyzed using methylene blue (MB) titration to determine clay content. Although, the MB filter paper spot test titration is simple, it is labor-intensive, subjective, and leaves no record for subsequent re-examination. Preliminary thermometric monitoring of the titration indicated a switch from endothermic to exothermic reaction during titration. We examined this nearly universal property of physicochemical processes as a potential replacement method to automate the MB clay titration, making use of literature data. We translated the isothermal enthalipmetric titration of montmorillonite using MB by Rytwo and Ruiz-Hitzky to an adiabatic thermometric titration (2003). The plot of temperature versus titrant volume gave two intersecting linear segments dependent on the titrated percentage of the clay''s cation exchange capacity (CEC). The MB filter paper spot test endpoint reflects the first excess MB that persists in the solid suspension, which also happens to be a function of the clay''s CEC. The spot test endpoint is correlated to the thermometric indicator point and, for montmorillonite, the two are related by an exact factor of two. Although this factor will naturally be dependent on the clay minerals in the samples, the analyses show that the thermometric indicator titration method is a viable replacement for the spot test. The proposed automation is commonplace as it is practiced with other types of titrations. [Copyright &y& Elsevier]

• The mechanism of organic electrode weakening self-discharge effect of dual-ion battery was explored. • The performance of metal-free dual-ion batteries in different ionic liquid electrolytes was investigated. • The method of reducing the dissolution of organic electrode in ionic liquid electrolyte was discussed. The strong self-discharge reaction is one of the key factors limiting the practical use of dual-ion batteries, which leads to low coulombic efficiency and discharge capacity loss. It is of great significance to effectively reduce the self-discharge effect through redox reactions between organic electrodes and electrolytes. Herein, a dual-ion battery study that uses 1,4,5,8-naphthalenetetracarboxylic dianhydride as the anode and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide as the electrolyte is conducted. Due to the introduction of organic materials, the storage mechanism of cations on the anode is changed, which weakens the self-discharge effect. The battery shows a low self-discharge rate of 6.12% h−1 and a high discharge capacity of 114 mAh g−1. The voltage declines by only 0.14 V after resting for 15 h due to the strong redox reaction between Pyr 14 + cations and the C O groups of NTCDA. Meanwhile, a double-layer filter paper system with small porosity is used to improve the cycle performance of the battery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chromogenic sensor for selective estimation of aqueous ferric ions was developed. • The chromogenic paper strip was prepared via doping tannic onto filter paper. • A visible color shift from white to purple was observed in the presence of Fe(III). • A concentration range of 10–190 ppm was monitored a detection limit of Fe(III). • The current sensor is a simple and practical tool for real-time detection of Fe(III). Investigation of chromogenic sensor which can selectively estimate ferric cations in aqueous environment with prospect to produce portable platforms is currently proposed. Herein, the chromogenic sensor (Tannic Acid@Filter Paper; TA@FP) was prepared via doping of tannic acid within filter paper to afford the excellent selectivity for ferric cations over various examined metal ions. The designed chromogenic sensor was applied for estimating ferric ions via turn-on detection, while, it could acquire a marked visible color shifting from white to purple hue depending on the total content of Fe (III) ions in the aqueous medium. Complete characterization of the designed sensor before and after its exploitation in estimation of ferric cations was systematically performed via different spectral and microscopic analyses. The functionalized TA@FP was quite sensitive for quantitative estimation of ferric ions with wide scaling linear concentration range of 10–190 ppm. Maximum sensitivity of the exploited platform was observed at very low concentration (10 ppm) rather than the higher concentrations. The correlation coefficient (R2 = 0.99) was closer to unity. The prepared chromogenic sensor could be described as a simple and practical sensing tool for real-time quantitative and qualitative assessment of Fe (III) cations. [ABSTRACT FROM AUTHOR]

White light solid-state lighting applications still face significant challenges due to insufficient efficient and stable red light emitting materials. Therefore, a series of orange-red fluorescent materials, CaLu 2-x Mg 2 Si 3 O 12 :xCe3+ (CLMS:xCe3+; x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) were prepared in this paper. Luminescence spectra testing revealed that the optimal concentration of Ce3+ ions in the crystal lattice is x = 0.04. At 460 nm excitation, the emission wavelength is approximately 592 nm. To enhance the thermal stability and luminescence performance of CLMS:Ce3+, the CaLu 1.96-y Me y Mg 2 Si 3 O 12 :0.04Ce3+ (Me = Sr, Ba; y = 0, 0.02, 0.05, 0.10, 0.15, 0.20) fluorescent materials were successfully prepared. It was found that phosphor's fluorescence intensity was enhanced after the introduction of Sr2+ or Ba2+ ions. Meanwhile, the phosphors were tested for thermal stability, and the emission intensities of CLMS:0.04Ce3+, CLMS:0.04Ce3+,0.10Sr2+, and CLMS:0.04Ce3+,0.05Ba2+ phosphors decreased to 77.60%, 85.53%, and 87.63% at 423 K, respectively. This proves that Sr2+ and Ba2+ ions have a positive effect on the thermal stability performance of CLMS:0.04Ce3+ phosphor. Testing of the w-LED devices, the CCT was reduced. The CRI was improved to 80.4 and 81.6 and luminescence efficiency was improved to 107.71 lm/W and 115.04 lm/W after Sr2+ or Ba2+ ions were introduced. In summary, this study demonstrates that CaLu 2-x-y Me y Mg 2 Si 3 O 12 :xCe3+ (Me = Sr, Ba) is an auspicious fluorescent material with high thermal stability, which is potentially informative for the field of white-light illumination. [ABSTRACT FROM AUTHOR]

Broadband cyan-emitting phosphors with strong absorption between 300 and 400 nm are ideal replacements for traditional blue and green phosphors used in commercial light-emitting diodes (LEDs). In this paper, a series of K 1-x AlSiO 4 : xCe3+(x = 0.02–0.06) broadband cyan phosphors were prepared using the traditional high-temperature solid state method and the cation un-equivalent substitution strategy. It was found that the KAlSiO 4 matrix has a monoclinic structure with high symmetry. The experimental and theoretical optical band gaps of the host were 5.6 eV and 4.86 eV, respectively. After doping with Ce3+, strong absorption was observed in the near ultraviolet region. The optimum Ce3+ doping concentration in the host was 0.04 as indicated by the strongest observed emission intensity. The full width at half maximum of the emission spectra of the series of samples are all greater than 120 nm and covered the blue and green wavelength ranges (370–600 nm). The luminous intensity of the K 0 · 96 AlSiO 4 : 0.04Ce3+phosphor at 150 °C was 91.1% of that at room temperature, and the Gaussian peak of the emission spectrum slightly broadened. These results were also combination with theoretical DFT calculations. It was found that the phosphor had very good thermal stability and rigidity. The phosphor was also mixed with a commercial red phosphor, interfaced with a UV chip and packaged into an LED. This LED was characterized and had a color rendering index greater than 90 across a broad range of drive currents. This work highlights the utility of the fabricated phosphor as means of simplifying white-light LED fabrication. [ABSTRACT FROM AUTHOR]

• Critical roles of A, B-site cations, and oxygen vacancies are revealed in Bi 0.15 Sr 0.85 Co 1− x Fe x O 3−δ perovskites. • BiSC 0.8 Fe 0.2 shows excellent OER activity and marvelous durability in 0.1 M KOH. • A link between bulk properties and OER activity has been established. • The highly A-site deficient surface layer also plays a critical role in OER. Development of perovskite-type electrocatalysts with high activity, excellent durability and affordable cost provides a promising solution to promote commercialization of clean energy technologies. Here we prepared Bi 0.15 Sr 0.85 Co 1− x Fe x O 3−δ (x = 0.2, 0.4, 0.6, 0.8, 1) perovskites by the conventional solid-state reaction route, and investigated their OER electrocatalytic activity and durability in 0.1 M KOH solution to reveal the critical role of A, B-site cations and oxygen vacancies. Results show the OER activity decreases with increasing x. The optimum composition, BiSC 0.8 F 0.2 , presents impressive electrocatalytic performances with low overpotential (330 mV on rotation disk electrode, and 283 mV on carbon paper electrode at 10 mA/cm2) and excellent long-time durability showing a small increase in the overpotential of 17 mV in 167.5 h. Comprehensive analysis and discussion on the bulk and surface properties reveal the critical role of A, B-site cations and oxygen vacancies on OER, and interrelations of Co2+ fraction, oxygen non-stoichiometry and the OER overpotential have been established. Most importantly, a highly A-site deficient surface layer is found on the as-synthesized perovskite, which facilitate OER by exposing more active B-site cations. This work not only reports a promising OER electrocatalyst with high activity and superior durability, but also provides perspectives on relational design for highly efficient and stable perovskite electrocatalysts for OER using solid-state reaction method. [ABSTRACT FROM AUTHOR]

• During the transportation and diffusion of cations, a stable solvated layer can be formed to prevent the charge exchange between the cation and the charged surface of nano SiO 2 particle. • When the concentration of salt solution is increased and the valence of cations is increased, the hydrogen bond is easier to break through the solvation layer to gather on the surface of nano SiO 2 particles. • When the cations transport to the position of 7 Å away from the surface of nano-SiO 2 particles, the short-range force begins to affect the movement of cations. When the cations transport to the position of 2 ∼ 3 Å away from the surface of nano-SiO 2 particles, the charge exchange occurs and the cations continue to oscillate. Nano-SiO 2 solution has great potential for application in the field of oil and gas exploration and development. However, its application is restricted due to the aggregation of nano-SiO 2 in stratum water. This paper studies the process of interaction between nano-SiO 2 particles and salt solutions by using the molecular dynamics simulation experiments, including the characteristics of transportation and diffusion of cations around the nano SiO 2 , the effect of cations on the recombination and destruction of hydrogen bonds, the interaction energy between cations and nano SiO 2. The main results are as follows. During the transportation and diffusion of cations in the solution, the hydrogen bonds of water molecules are broken, so that the hydrogen bonds can be rearranged, and a stable solvated layer can be formed. In the solvated layer, the repulsive force of solvation can prevent the charge exchange between cation and the charged surface of nano SiO 2 particle. Compared with the monovalent salt solution, more divalent cations can break through the solvation layer to generate the charge exchange on the surface of nano-SiO 2 particle. More divalent cations can conduct small amplitude oscillation movement near the surface of nano-SiO 2 particle due to the strong electrostatic effect. When the concentration of salt solution is increased (3000 mg/L → 7000 mg/L) and the valence of cations is increased (monovalent → bivalent), the hydrogen bond is easier to break through the solvation layer to gather on the surface of nano SiO 2 particles, which is unfavorable to the stability of nano SiO 2 particles. When the cations transport to the position of 7 Å away from the surface of nano-SiO 2 particles, the short-range force (including hydrogen bond force, van der Waals force, and electrostatic force) begins to affect the movement of cations. When the cations transport to the position of 2 ∼ 3 Å away from the surface of nano-SiO 2 particles, the charge exchange occurs between cations and the surface of nano SiO 2 particle, so that the local energy is increased and the cation continues to oscillate. In summary, with the increasing of concentration of salt solution and the valence state, more cations can break through the solvation layer to be adsorbed on the surface of nano SiO 2 particle, showing that the ability of transportation and diffusion of cations is weakened, the interaction energy between nano SiO 2 particle and salt solution molecules is enhanced. The electrostatic force is the main force to destroy the stability of nano SiO 2 particle. The conclusions can provide a certain theoretical basis for the efficient application of nano-SiO 2 materials in the field of oil and gas exploration and development and other interrelated industry. [ABSTRACT FROM AUTHOR]

Abstract: Usually, the differentiation of inks on questioned documents is carried out by optical methods and thin layer chromatography (TLC). Therefore, spectrometric methods were also proposed in forensic literature for the analysis of dyes. Between these techniques, laser desorption/ionization mass spectrometry (LDI-MS) has demonstrated a great versatility thanks to its sensitivity to blue ballpoint ink dyes and minimal sample destruction. Previous researches concentrated mostly on the LDI-MS positive mode and have shown that this analytical tool offers higher discrimination power than high performance TLC (HPTLC) for the differentiation of blue ballpoint inks. Although LDI-MS negative mode has already been applied in numerous forensic domains like the studies of works of art, automotive paints or rollerball pens, its potential for the discrimination of ballpoint pens was never studied before. The aim of the present paper is therefore to evaluate its potential for the discrimination of blue ballpoint inks. After optimization of the method, ink entries from 33 blue ballpoint pens were analyzed directly on paper in both positive and negative modes by LDI-MS. Several cationic and anionic ink components were identified in inks; therefore, pens were classified and compared according to their formulations. Results show that additional information provided by anionic dyes and pigments significantly increases the discrimination power of positive mode. In fact, it was demonstrated that classifications obtained by the two modes were, to some extent, complementary (i.e., inks with specific cationic dyes not necessarily contained the same anionic components). [ABSTRACT FROM AUTHOR]

The insulation failure is common in high voltage transmission. Based on experimental structure, this paper adopts the finite element method to establish the mathematical model of the short-circuit insulator discharge. Simplify the insulator discharge into a short circuit process between the upper and lower plates, and explore the process of generation, adsorption and neutralization of electrons, positive ions and negative ions, studied how the space charge variation affects the electric field intensity, and analyzed the distribution of each type of ionization products from the wires during the discharge. The results show that: when the insulator is short-circuited and discharged, the area with larger electric field strength is mainly concentrated near the upper plate; the electric field intensity in the discharge space tended to stabilize at the completion of the discharge; when the short-circuit wires were fused, the electron concentration remained stable for a short while at certain positions of the discharge space; as the discharge continued, the electron concentration at these positions declined rapidly; the electrons moved to the plates, causing fluctuations in electric field intensity; the variation of electron concentration during the discharge obeyed the Gaussian distribution. The research results provide the experimental evidence and theoretical reference for avoiding transient discharge in equipment operation. [ABSTRACT FROM AUTHOR]

This paper presents the basic physical and numerical principles of a fluid model of the negative ions source. The model gives self-consistent two-dimensional description of the source, including the neutral gas flow, plasma chemistry, RF coupling in the source driver and plasma transport through the magnetic filter. The different particle species (electrons, the three types of the positive ions: H + , H 2 + , H 3 + , negative ions H − and the neutral species: hydrogen atoms H and molecules H 2) are described by separate continuity equations and the electron temperature is governed by the electron energy balance equation. The particle fluxes are found from momentum equations neglecting the inertia terms (drift-diffusion approximation). The electrostatic coupling between electrons and ions is described by the Poisson equation. The paper focuses on details of the RF model and on the initial code developments to simulate the currents in the source induced by the RF currents flowing in the feeding coils. In our approach, the RF electrical field is split in a plasma part plus another one in vacuum, E = E p + E V , which simplifies the boundary conditions for E p while E V is obtained from a theoretical formulation for the field generated by a current loop, which results in a fast and flexible numerical algorithm providing converged solution for the RF field after a few iterations, even for the cases with high conductivity of the plasma. The numerical method is based on finite volume approximation and 9-point discretization is used to account on anisotropy due to magnetic field. The semi implicit numerical solver allows for large time steps (> 1000 × explicit time step) producing steady-state solution in a reasonable time (few hours for a typical mesh). The RF model has been successfully coupled to the fluid equations of the source and self-consistent solutions are analyzed in order to see the influence of the driver parameters and RF model assumptions (e.g. stochastic conductivity, induced magnetic field) on the heating efficiency and the plasma dynamics. It has been found that without magnetic field the plasma dynamics in the SPIDER source is almost independent on the details of the RF coupling model. • 2D fluid model of negative ion source is presented, including RF coupling. • Without magnetic field, results are almost independent on details of the RF model. • With magnetic field, the RF coupling model strongly affects the plasma dynamics. [ABSTRACT FROM AUTHOR]

The retarding effect of reaction products on the rate of dissolution of minerals is explored in this paper. It is shown that this retarding effect is not correctly described by methods based on the equilibrium for the overall reaction, such as those of chemical affinity. Such models frequently fail to describe the kinetics of the reverse reaction. Instead, in line with the mechanism of dissolution proposed in earlier papers in this series, it is proposed that the removal of surface species to form anions and cations in solution occurs in parallel partial reactions. An implication of the parallel nature of these partial reactions is that either of the partial reactions might reach equilibrium before that of the other partial reaction. This gives rise to the novel concept of partial equilibrium for dissolution reactions. The equations for this partial equilibrium are derived for both acidic and alkaline solutions. The application of the proposed theory to the dissolution of calcite, muscovite, feldspar and kyanite are given as examples to illustrate the concepts of full and partial equilibrium. [ABSTRACT FROM AUTHOR]

This paper studied the recovery of uranium (VI) from 5.3 M phosphoric acid by bis(1,3-dibutoxypropan-2-yl) phosphoric acid (BiDiBOPP)/di- n -hexyl octyl metoxy phosphine oxide (di-n-HMOPO) and 5 analogs of BiDiBOPP mixed with tri- n -octylphosphine oxide (TOPO) diluted in Isane IP 185. First, this paper shows that the experimental and calculated distribution coefficients of uranium (VI) as a function of the concentration of BiDiBOPP and di- n -HMOPO match by using a thermodynamic model previously developed and validated on the bis(2-ethylhexyl) phosphoric acid (D2EHPA)-TOPO system. In this model the formation of complexes between the cationic extractant (HL) and the solvatant extractant (S) such as (HL) 2 , (HL) 2 S, (HL) 2 S 2 and (HL) 5 S and the recovery of uranium (VI) as UO 2 (HL) 2 L 2 S, UO 2 L 2 S and UO 2 (HL) 2 L 2 were taken into account where L refers to the deprotonated form of the cationic extractant HL. Secondly, the investigation of the extraction of uranium (VI) by the BiDiBOPP analogs mixed with TOPO in Isane IP 185 showed that the presence of oxygen atoms in the two aliphatic chains of BiDiBOPP and the increase of the hydrophobicity of these chains influence strongly the extraction properties. [ABSTRACT FROM AUTHOR]

Rare earth substituted yttrium iron garnets (Re:YIG) are an important class of magnetic ceramics which can be widely used in microwave-related, magnetic and magneto-optic devices. For this reason, this paper investigates the structural behavior and magnetic performance of the Eu, Ce-YIG garnet by the traditional ceramic technique. Oxide powders with stoichiometric ratios were blended to achieve the chemical composition (Y 2.75-x Ce 0.25 Eu x Fe 5 O 12 where x = 0, 0.15, 0.25 and 0.35). The mixed powder was calcined at 1000 °C for 20 h in the air condition, sintered at 1350 °C for 14 h and then the sample became denser at 1420 °C for 6 h in the air. The XRD results showed that the Eu3+ ion is effective in solubilizing the Ce3+ ion and that the lowest amount of required Eu to dissolve the 0.25 Ce is about 0.25 in the structure. The XPS data confirmed that the Fe2+ and Ce4+ cations are not present in the structure. Moreover, the substituted garnet with 0.25 Ce and 0.25 Eu increased saturation magnetization by about 21% compared to the pure YIG. The magnetic coercivity increases from 16.41 Oe for the pure YIG to 25.52 for the Y 2.75 Ce 0.25 Fe 5 O 12 and then decreases with the Eu substitution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Formation energy and Goldschmidt tolerance factor of cation doped CsPbI 3 are calculated. • PBE, PBE + SOC and HSE06 are used to calculate the band structure. • Light absorption spectra of the doped CsPbI 3 all shows red shift. Among all inorganic perovskite, CsPbI 3 has the closest ideal bang gap for solar cells. However, the instability of metal halides hinders its commercial application. The doping of A-site organic cations might improve the stability of perovskite and also make the bandgap adjustable, thus enhance its photoelectric properties. In this paper, the structure stability, electronic structure and optical properties of CsPbI 3 with five different organic cations (H 3 NNH 2 +, CH 3 NH 3 +, C 3 H 6 NH 2 +, CH 3 NH 2 CH 3 +, CH 3 CH 2 NH 3 +) partially alternative doping instead the A site cation have been studied by using the first principles within density functional theory. In order to get accurate description of the bandstructure information, different exchange–correlation functions, e. g. PBE, PBE + SOC and HSE were used to describe the calculated systems, our calculation results indicated that the PBE exchange–correlation function can describe the electronic properties of the systems very well in this paper. Formation energy calculation indicates that all the doping systems are thermally stable; and all the doped CsPbI 3 show good tolerance factor according Goldschmidt rule. Among the five different doping systems, the bandgap of doped H 3 NNH 2 + will decrease to 1.28 eV, while the bandstructure of other doped cations will widen the bandgap. The maximum bandgap increased to 1.65 eV with doping C 3 H 6 NH 2 +. However, all the band structures are mainly contributed by inorganic framework. The results suggest that the structure doped organic cations can be exited stably, and the band edge of the optical absorption spectrum will be redshifted. These properties can provide research ideas for the subsequent research of A-site doping organic cations. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Halloysite nanotubes (HNTs) was modified with 3-aminopropyltriethoxysilane. • Modified and unmodified HNTs were used as reservoir for Zn2+ cations. • Higher concentration of zinc cations were released from modified HNTs. • Modified HNTs doped with Zn2+ improved protective function of epoxy ester coating. Abstract This paper deals with the loading of halloysite nanotubes (HNTs) with Zn2+ cations. The aluminol groups of HNTs were grafted by 3-aminopropyltriethoxysilane (APTES) to enhance Zn2+ loading. FTIR proved modification of HNTs. Electrochemical evaluations of bare steel in saline solution showed higher corrosion inhibition provided by an extract of modified HNTs connecting to a higher concentration of zinc cations released from modified HNTs. The HNTs were incorporated into an epoxy ester coating, and electrochemical behavior of intact and scratched coatings was evaluated. Active corrosion protection at the defect areas of the coatings was proved by EDS analysis. [ABSTRACT FROM AUTHOR]

Abstract This paper demonstrates the importance of Ca2+ in formation water on low salinity oil recovery, and the importance of Mg2+ in formation water with Ca2+ and alone. A series of Berea sandstone cores were flooded with formation water (FW) water as a secondary flood, then low salinity (LS) water was injected for the tertiary stage. The temperature of the experiments was 90 °C (reservoir temperature). Surface reactivity tests were run where water saturated cores were flooded with the same FW and LS water that was used in oil recovery experiments. While injecting brines, samples of the effluent were analyzed for pH, Mg2+, and Ca2+. We also measured contact angles between sandstone cores and crude oil in the presence of LS water and FW after some flooding stages. Oil recovery tests with double Ca2+ and Mg2+ (especially Ca2+) concentration in FW revealed a lower LS water EOR effect, indicating that the cores are apparently more water-wet. The LS water effect was much larger when the concentration of Ca2+ and Mg2+ in the FW was decreased by half. Additionally, the oil recovery due to LS water is greater for cores with Mg2+ abundance in the FW than for those with Ca2+. The LS water effect is greater as the Mg2+ exists. Surface reactivity tests, contact angle measurements, and spontaneous imbibition results were consistent with the oil recovery tests. Generally, contact angle measurements and spontaneous imbibition predict similar wettability trends because both tests depend on the same physics concepts. In this study, we claim that the smaller Mg2+ radius causes Mg2+ to be more tightly enveloped in water molecules than Ca2+, which might mean that Ca2+can actually get closer to the oil and mineral surfaces than Mg2+and have a bigger effect. The tests conducted in this study to investigate the role of divalent cations on LS water response should be routine practice as a supplement to conventional core flooding experiments. Such tests will give the operator clear guidance as to proper LS water design to maximize oil recovery for a given FW and core. Highlights • The oil recovery by LSW is greater when Mg2+ abundance in the FW than Ca2+. • Mg2+ in FW is more effective than Ca2+ on oil recovery even at high concentrations. • From SRT, LSW improves sweep efficiency at lower (Ca2+ & Mg2+) concentrations in FW. • The CA and SI measurements supported the Mg2+ dominant role on LSW EOR effects. • –COOCa+ more tightly bound to minerals than –COOMg+, Ca2+ lowers oil recovery. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the application of quantum mechanical (QM) energy calculations, QM optimisations and MD simulations to explore the stability of a human telomeric guanine quadruplex, containing potassium and sodium cations. G-quadruplexes are of great biological interest as it has been suggested that they offer a novel path to cancer inhibition. By understanding the stability and geometry of these DNA features gives us the ability to design ligands which can bind and stabilise the G-quadruplex. There are significant structural differences between the potassium containing crystal structure of human telomeric G-quadruplex and the sodium containing NMR structure; in this paper, we investigate the energetics and dynamics of the potassium derived crystal structure and a model for the sodium containing structure. QM investigations upon the 12 G-quadruplex core, extracted from the human potassium quadruplex crystal structure, indicate that replacement of the potassium cations with sodium yields an energetically more favourable structure. However, attempts to geometry optimise both structures at the QM level proved unsuccessful, the structure of the partially optimised potassium containing G-quadruplex retains significant structural integrity with respect to the original crystal structure, whilst the sodium containing G-quadruplex shows significant structural distortion. QM investigation of the 12 G-quadruplex core containing no cations unsurprisingly yields a highly unfavourable energetic structure. MD simulations on the complete quadruplex structure, containing potassium cations, yields a remarkably stable structure after 4ns of simulation, the most significant deviation from the original crystal structure being the loss of the capping potassium cation from the structure. MD simulation of the sodium containing quadruplex for 4ns show significant structural reorganisation compared with the original potassium containing crystal structure. [Copyright &y& Elsevier]

• The replacement of Ca2+ by Na+ can effectively weaken hydrated cation bridges by changing the structure of hydrated cations. • AO and EDTA can affect the hydration between Ca2+ and water molecules to destroy hydrated cation bridges. • Hydrogen bond disrupting agents can destroy the hydrogen bond network by reducing the dipole moment of water molecules. Hydrated cation bridges, in which hydrated cations connect oil and rock by hydrogen bonds, are the primary reason for crude oil adhesion on the surface of rock in low-permeability sandstone reservoirs. How to cut off hydrated cation bridges is important for higher oil washing efficiency. As a hot topic, more and more attention has been given to the study of hydrated cation bridges in recent years, but the studies mainly worked on the formation mechanism, no effective way for destroying hydrated cation bridges has been reported. In this paper, the micro influence mechanism of cation exchange, cation shielding agents and hydrogen bond disrupting agents on hydrated cation bridges was explored via molecular dynamics simulation. The replacement of Ca2+ by Na+ can effectively weaken the hydrated cation bridges by changing the structure of hydrated cations between oil and quartz and reduce the force required to peel oil droplets off quartz by 51%. Because of the interaction between cation shielding agents (AO and EDTA) and Ca2+, the appearance of cation shielding agents can affect the hydration between Ca2+ and water molecules, and reduce the force required to peel oil droplets off quartz by 37% and 4.9%. Sodium glycolate, urea and guanidine hydrochloride, which can destroy the hydrogen bond network between oil and quartz by reducing the dipole moment and polarity of water molecules, can reduce the force required to peel oil droplets off quartz by 9.5%, 19.7% and 22.0%. This research aims to explore the efficient destruction method of hydrated cation bridges and provide theoretical support for the efficient development of low-permeability sandstone reservoirs. [ABSTRACT FROM AUTHOR]

The Heating Neutral Beam Injectors (HNBs) for ITER will have to deliver 16.7 MW beams of H/D particles at 1 MeV energy. The beams will be produced from H −/ D − ions, generated by a radiofrequency plasma source coupled to an ion acceleration system. A prototype of the ITER HNB ion source is being tested in the SPIDER experiment, part of the ITER Neutral Beam Test Facility at Consorzio RFX. Reaching the design targets for beam current density and fraction of coextracted electrons is only possible by evaporating cesium in the source, in particular on the plasma facing grid (PG) of the acceleration system. In this way the work function of the surfaces decreases, significantly increasing the amount of surface reactions that convert neutrals and positive ions into H −/ D −. It is then of paramount importance to monitor the density of negative ions and the density of Cs in the proximity of the PG. Monitoring the Cs spatial distribution along the PG is also essential to guarantee the uniformity of the beam current. In SPIDER, this is possible thanks to the Cavity Ringdown Spectroscopy (CRDS) and the Laser absorption Spectroscopy diagnostics (LAS), which provide line-integrated measurements of negative ion density and neutral, ground state Cs density, respectively. The paper discusses the CRDS and LAS measurements as a function of input power and of the magnetic and electric fields used to reduce the coextraction of electrons. Negative ion density data are in qualitative agreement with the analogous measurements in Cs-free conditions. In agreement with simulations, Cs density is peaked in the center of the source; a top/bottom non uniformity is also present. Several effects of plasma on Cs deposition and negative ion production are presented. [ABSTRACT FROM AUTHOR]

Recently, mixed cation/anion perovskite solar cells (PSCs) have attracted considerable attention due to their higher stability and better photovoltage performance than pure ABX 3 perovskite solar cells. However, the fundamental mechanism of such an improvement has not yet been fully investigated. In this paper, substituting cesium cation for methylammonium cation of the (1 0 0) surface of CH 3 NH 3 PbI 3 perovskites was made to study the improvement of stability and electronic properties of MAPbI 3 perovskite. The results show that the decomposition energies of perovskite increase with the increased concentration of doping Cs + , which indicates that the thermodynamic stability can be enhanced. By analyzing the Bader charge and charge density difference of the perovskite/TiO 2 heterostructures, we find that the system of doping Cs + transfers more electrons to TiO 2 since the distance between I and Ti reduces. Doping Cs + can make the PbI 6 octahedral frame tilt and the tilting orientation is different for different concentration of Cs + . Meanwhile, the band gap increases with the increased concentration of Cs + , which leads to the increase in open circuit voltage V OC . This study can give some guidance for improving stability and PCE of the perovskite solar cells. [ABSTRACT FROM AUTHOR]

In this paper we report, for the very first time, the possibility to UV-crosslink a glass fibre reinforced epoxy composites. We have demonstrated that the crosslinking reaction proceeds via a radical induced cationic frontal polymerization (RICFP), where the UV-surface activation of cationic ring opening polymerization is able to promote the heat front that will activate a thermal initiator in the deeper layers. Because of the very high velocity of the reaction we could obtain quickly epoxy composites maintaining the good thermo-mechanical properties. [ABSTRACT FROM AUTHOR]

This paper summarizes the development and testing of novel graphene oxide (GO) membranes for the removal of natural organic matter (NOM) from raw water sources used for drinking water supply. In this work, two trivalent cations, Al 3+ and Fe 3+ , were employed as crosslinking agents to stack GO nanosheets layer by layer on a PVDF membrane support, in order to fabricate a suitable GO membrane. The trivalent cations greatly improve the bonding strength between the GO nanosheets through electrostatic forces and coordination bonds, and thus enhance the stability of the GO membrane; the integrity of the membrane in a range of solutions could be maintained for over a month. The initial interlayer spacing of GO nanosheets (0.80 nm) could be increased up to 0.86–0.95 nm by changing the Al 3+ or Fe 3+ ion concentration. It was found that the GO membrane flux ranged between 79 and 902 LMH/MPa when treating three representative NOM solutions and a real surface water. A relatively low thickness of the GO layer induced a higher flux of the GO membrane when prepared with the same cation concentration, while increasing the cation concentration resulted in a decline in flux. The flux of the Fe 3+ cross-linked GO membrane was approximately 1.1–2.3 times that of the Al 3+ cross-linked GO membrane, while both cation-modified GO membranes achieved a similar separation efficiency of the organic contaminants. The study has demonstrated a facile approach to the fabrication of a novel, stable GO membrane employing Al 3+ /Fe 3+ ions as crosslinking species, in order to utilize the excellent properties of GO and produce a GO membrane with a high flux and organic removal performance for water treatment. [ABSTRACT FROM AUTHOR]

This paper reports the systematic performance evaluation and mechanism elucidation of a multi-layered graphene oxide (GO) membrane in removing ionic and organic species from water at different pH levels. The rejections of representative monovalent (Na + , Cl - ) and multivalent ions (SO 4 2- , Mg 2+ ) as well as organic dyes (methylene blue, rhodamine-WT) and pharmaceutical and personal care products (triclosan, triclocarban) by the GO membrane were tested in a reverse osmosis membrane system. It was found that, at pH 7, the GO membrane exhibited high removal of multivalent cations/anions and all tested organics, regardless of their charges, sizes, or hydrophobic properties, but low removal of monovalent ions. Such removal behavior is dramatically different from that of traditional nanofiltration membranes, which are often negatively charged and can only remove multivalent ions and organics that also bear negative charges. As pH varied, the key properties (e.g., charge, interlayer spacing) of the GO membrane were significantly changed, leading to different pH-dependent interfacial phenomena and separation mechanisms, and demonstrating the promise of using the GO membrane as a pH-responsive membrane. It was also revealed that the molecular shape of some organics (e.g., triclocarban) greatly affected their removal due to the mobility and thus π-π interaction of such organics with the carbon surface of the GO membrane. Finally, implications for the future development of high-performance GO membranes are discussed. [ABSTRACT FROM AUTHOR]

The Heavy Ion Beam Diagnostic of the tokamak ISTTOK is operated with a 20 keV Xe + ion beam and a multiple cell array detector to collect the secondary Xe 2+ ions created along the primary beam path by ionizing collisions with plasma electrons. In this paper an improved multi-channel multi-slit 90° cylindrical analyzer for the plasma potential fluctuations measurements in ISTTOK is described. The energy resolution of the ideal 90° cylindrical analyzer indicates the value of minimal detectable change in plasma potential to approximately 5 times higher than the expected plasma potential fluctuation level. In addition, the ideal 90° cylindrical analyzer is characterized by finite first order angular aberration. The SIMION code has been used to investigate the properties of real 90° cylindrical analyzer with inclusion of fringing fields. As a result of numerical simulations, the necessary energy resolution has been obtained in novel approach of operation in combining electric field deflection and deceleration with biased exit electrode. In addition, almost the first order focusing in the range of ±2° has been obtained exploiting the lens effect of fringing field together with optimization of the initial conditions at the beam entrance. A split-plate and a multiple cell detection systems at the analyzer exit are also discussed. [ABSTRACT FROM AUTHOR]

The structure of polyelectrolyte substrates could be changed from swelling to collapse by exchanging different electrolyte solutions. However, few investigations explained the phenomenon at the molecular level. In this paper, we employed a molecular dynamics method to simulate the structural changes of poly(methacrylic acid sodium) (PMMA) substrates with the presence of pure water, NH 4 Cl, tetramethylammonium bromide (TMAB) and tetraethylammonium bromide (TEAB) solution. The simulated results show that the percentage of water molecules penetrated into the substrate and the height of PMMA substrates gradually decrease following the order pure water > NH 4 + > TMA + > TEA + . This may be ascribe to the hydrophobic interaction between the solute cations and water molecules, which can exclude water molecules from the substrates and further influence the height of PMMA substrates. In particular, through the observation at the molecular level, it is obvious that the existence of water bridge structure and salt bridge structure formed between penetrated particles and PMMA chains play a key role in the structural change of PMMA substrates. Water bridges can induce the swelling of PMMA substrates and salt bridges will result in collapse happening. This work may promote a further understanding of the cationic effects on the structure of PMMA substrates at the molecular level and provide a new insight to study the interfacial micro-structure of other biological substrates in future. [ABSTRACT FROM AUTHOR]

(A) The structure of STCMs, (B) The model of STCMs based artificial transmembrane channels. [Display omitted] • Synthetic transmembrane channel molecules (STCMs) formed by acyclic cucurbiturils and pillararene at first time. • STCMs were used to study of transmembrane channels at first time. • STCMs can stably insert into the cell membrane and generate stable currents. Biomimetic transmembrane channel molecules developed through chemical synthesis strategies were used for treat genetic diseases which due to the alterations in the channel structure of native membrane proteins and ion transport is deregulated. In this paper, we designed and constructed a novel synthetic transmembrane channel molecules (STCMs), which based on acyclic cucurbiturils (ACBs) and pillar[5]arene (PA[5]). STCMs could imitate the function of natural channel protein molecules and reveal the possible existence structure, there is a hope for new treatment options for genetic diseases. The structure of STCMs have been identified by NMR and FT-IR, the results of fluorescence experiments showed that it could effectively insert into the phospholipid bilayer, specifically recognize and transmit K+. Whole-cell patch-clamp experiments showed that STCMs could insert into the cell membrane of HEK293T cells, and could form channels on the cell membrane to generate current. These works will help to understand the relationship between the structures and properties of STCMs and the selectivity and efficiency of ions or polar molecules. This study presents the molecular structure and function of STCMs which may form a basis for explore the scientific laws of transmembrane transporter. [ABSTRACT FROM AUTHOR]

The present paper discusses the electrodeposition of nano-Aluminum using aromatic cation based ionic liquids. Three imidazolium chloride salts were employed, in ultrapure quality: l-ethyl-3-methyl-imidazolium chloride [EMIm]Cl, l-benzyl-3-methyl-imidazolium chloride [BzMIm]Cl and l,3-dibenzyl-imidazolium chloride [DBzIm]Cl, respectively. Anhydrous Aluminum chloride (AlCl 3 ) salt was used as a source of Aluminum ions in the ionic liquids. This research aims to achieve this goal by investigating the Aluminum coatings on gold substrate and study the effect of changing the organic cation on the properties of the resulting Al-coatings. SEM-EDAX analyses were used to determine the film composition. It was found that the particle size of the Al-deposites was dramatically reduced from the micrometer regime down to the nanometer regime with a change in the substituents of the imidazolium cations from EMIm to DBzIm, respectively. This means that the more the aromatic rings in the cation, the finer the particle size. Thickness and adhesion of the Al-deposits were decreased in the presence of the aromatic rings. [ABSTRACT FROM AUTHOR]

The present paper is devoted to the properties of sulfonated cation-exchange membranes obtained by radiation chemical grafting polymerization of styrene with divinylbenzene on a polyethylene film. The mechanical and transport properties (conductivity, diffusion permeability, and transport numbers) of the membranes obtained with various amounts of a cross-linking agent (0–3.5%) and degrees of polystyrene grafting (23–32%) were investigated in comparison with commercially available membranes, i.e. Nafion® 117 and Neosepta® CMX. Tensile strength values around 15–20 MPa were obtained, and they increased with increasing cross-linker amounts. The conductivity of membranes containing no cross-linking agent reached 8.4·10 −2 Ω −1 cm −1 at 25 °C and high relative humidity. As the amount of the cross-linking agent increased, the water uptake in membranes and their conductivity at high relative humidity decreased, whereas the activation energy of conductivity increased. At low humidity (RH=30%), the water uptake and conductivity increased with increasing amounts of the cross-linking agent. The membranes based on cross-linked polystyrene had low diffusion permeability, while the associated cation transport numbers were higher than those with commercial Nafion® 117 membrane. The calculated theoretical power of reverse electrodialysis batteries based on the best membranes was 10% higher than that of the battery based on the Neosepta® CMX membrane. [ABSTRACT FROM AUTHOR]

The Alice far-ultraviolet spectrograph in operation around the comet 67P/Churyumov–Gerasimenko on the Rosetta spacecraft experiences an anomalistic feature (AF) that is ubiquitous at comet separations less than 450 km. This feature is highly temporally variable and displays no relation to any studied parameters with the exception of comet separation. This paper tests several possible causes with simulations and finds that positive ions produce a partial explanation for the anomaly, but still finds no definitive source of the AF. [ABSTRACT FROM AUTHOR]

In this paper, surface roughness of self-supported montmorillonite clay films was studied by the use of fractal analysis to study its links with various inter-foliar cations, mechanical properties, and permeability. The Hurst exponent of fractional Brownian motion was estimated by maximum likelihood from optical images in reflection mode. Images corresponding to films with different inter-foliar exchanged cations visually show significant texture variations. It is confirmed by a continuous decrease of H parameter toward less correlated textures as one goes from the samples exchanged with monovalent ions to those exchanged with divalent and finally trivalent ions. The same films were analyzed while they were submitted to mechanical tensile stress. The films exchanged with the most charged cations or less hydrated ones do not show any evidence of texture change and the H parameter is almost constant. Concerning the permeability study, less permeable parent cakes – with hydrated monovalent cations – lead to relatively smooth and less disturbed surface films with high H parameter. In the opposite, very permeable cakes give birth to anti-persistent relief. [ABSTRACT FROM AUTHOR]

In the last decades, ion current sensing has been widely recognized as a promising approach to the engine knock/super knock detection. However, ion current formating mechanism under engine knocking conditions is yet to be revealed, which substantially hinder the further development of ion current based knock detecting technology. In this paper, the ion current signals detected under engine knocking conditions are investigated both experimentally and numerically. In a spark ignition engine, the ion current signal and combustion pressure are analyzed in both time and frequency domain. Besides, a multi-physics CFD model, which incorporates compressible fluid dynamics, neutral/charged species reaction kinetics and flame plasma hydrodynamics, is constructed in this work. Then the combustion process, the flame - pressure wave interaction and the motion of the charged species are analyzed, and the key features of the ion current signal under knocking conditions are studied. The multi-physics model indicates that the in-cylinder distribution of positive and negative charged species is almost the same due to the ambipolar diffusion of the electrons, and then the ion current can be analyzed via observing the positive ion flux solely. By combining the experimental and numerical results, it is revealed that the ion concentration is correlative to the temperature in a non-linear way, and the ion current mainly responds to the low frequency pressure oscillation mode. Correspondingly, the relation between the ion current oscillating amplitude and the knock intensity is non-linear. For knocking at high load conditions, both the amplitude of ion current signal and the ion concentration can respond to the oscillation of local pressure and knocking intensity. In particular, the signal oscillation becomes insignificant when knocking intensity KI < 0.85. [ABSTRACT FROM AUTHOR]

The aim of this paper was to investigate the influence of some surfactants of different chemical character (SDS, CTAB, TX-100 or their equimolar mixtures) on the adsorption and electrokinetic properties of the cationic starch (CS)/alumina system. The obtained results show that CS creates multilayer complexes with SDS, TX-100 and their mixture, but does not interact with CTAB. The reason for that is connected with chemical character of the polyelectrolyte and the above-mentioned surface active agents. Formation of complexes was confirmed by the surface tension measurements and by the measurements of surfactants adsorption at the alumina surface in the presence and absence of CS. The crucial information about both the electrokinetic properties of the system and the structure of the adsorption layer was obtained from the surface charge density and zeta potential measurements. The obtained data showed the specific structure of the adsorption layer polymer/surfactant/metal oxide. According to the results the polymer is directly bonded to the surface whereas the surfactants are present in the upper parts of the electrical double layer. [ABSTRACT FROM AUTHOR]

Result of beam scattering experiments on dynamics of chemical (bond-forming) reactions of molecular dications and trications are briefly reviewed. Both studies of crossed-beam scattering experiments and experiments using advanced position-sensitive coincidence method and their achievements that added to a better understanding of collisional mechanisms and energy deposition in products of this class of processes are discussed. In addition, results of other non-scattering methods (mass spectrometric, guided beam, time-of-flight) are briefly mentioned, if relevant to the subject of the paper. [ABSTRACT FROM AUTHOR]

The role of chemical components of cork in the sorption of several pesticides has been investigated. For this purpose raw cork and three cork extracted fractions (i.e. cork free of aliphatic extractives, cork free of all extractives and cork free of all extractives and suberin) were used as sorbent of three ionic pesticides (propazine, 2,4-dichlorophenoxy acetic acid (2,4-D) and alachlor) and five non-ionic pesticides (chlorpyrifos, isoproturon, metamitron, methomyl and oxamyl) with a log K ow within the range −0.47 to 4.92. The effect of cations on the ionic pesticides, propazine and 2,4-D sorption was also analyzed. Results indicated that the highest yields were obtained for chlorpyrifos and alachlor sorption onto raw cork (>55%). After removal of aliphatic extractives sorption of all pesticides increased that ranged from 3% for propazine to 31% for alachlor. In contrast, removal of phenolic extractives caused a sorption decrease. Low sorption yields were obtained for hydrophobic pesticides such as metamitron, oxamyl and methomyl (<11%) by using all cork fractions and extremely low when using raw cork (<1%). FTIR analysis was useful to indicate that lignin moieties were the main components involved on the sorption process. Modelling calculations evidenced that π-stacking interactions with the aromatic groups of lignin play a major role in determining the adsorption properties of cork toward aromatic pesticides. Results presented in this paper gain insights into the cork affinities for pesticides and the interactions involved in the sorption process and also enables to envisage sorption affinity of cork for other organic pollutants. [ABSTRACT FROM AUTHOR]

In this study, the efficiency of air cleaners in removal of chemical components of PM 2.5 (PAHs, heavy metals, and ions) in the indoor air of dormitories of Tehran University of Medical Sciences, Iran were assessed. 12 rooms were selected and randomly divided into two groups: sham air purifier system deployed room (SR) vs. true air purifier system deployed room (TR). 24-h PM 2.5 samples were simultaneously collected in both TR and SR on PTFE filter papers at a flow rate of 5 L/min. The results showed overall removal efficiency of 76.5 ± 15.5%, 63.1 ± 22.5%, and 66.2 ± 24.8% for PAHs, heavy metals and ions, respectively. Moreover, the fraction of positive ions decreased when air purifiers were used in the rooms. The results showed that the smoking is an important influencing factor on the indoor air quality; smoking can leads to reduction in removal efficiency of PAHs, heavy metals and ions by 26%, 40%, and 51%, respectively. An air purifier could decreased the PM 2.5 even lower than the WHO annual guideline level in non-smoker rooms. The present study revealed that use of indoor air purifiers can significantly reduce the risk of carcinogenicity and non-carcinogenicity attributed to heavy metals and PAHs, especially in places without a smoker. [Display omitted] • Efficiency of air purifiers (AP) in removal of components of PM 2.5 was investigated. • The results showed removal of 76.5%, 63.1%, and 66.2% for PAHs, metals and ions, respectively. • Smoking leads to efficiency reduction of PAHs, metals and ions by 26%, 40%, and 51%, respectively. • AP could decline the PM 2.5 even lower than the WHO guideline in non-smoker rooms. • AP can significantly reduce the health risks attributed to metals and PAHs. [ABSTRACT FROM AUTHOR]

Abstract: Numerous mixed ionic electronic conducting materials with a perovskite structure have been investigated in the literature as potential membrane materials for oxygen separation applications. However, the effect of cation substitution in the A site of a perovskite structure on the oxygen semi-permeation flux is not clearly understood. The goal of this paper is to provide insight into the effect of cation substitution in the A-site on oxygen semi-permeation flux in La0.5A0.5Fe0.7Ga0.3O3−δ and La0.5A0.5Fe0.7Co0.3O3−δ perovskite membranes with A = Ca, Sr, and Ba. In addition, the rate-determining step in the trans-membrane oxygen transport was clearly identified based on oxygen diffusion and oxygen surface exchange coefficients for these two perovskite membrane series. [Copyright &y& Elsevier]

This paper demonstrated the effect of cation substitution and cation deficiency in M-type hexaferrite on the phase formation, sintering behavior and magnetic properties. Bi substitution effectively promotes the mass transfer in the sintering process by forming liquid phase, so the Bi–Co–Ti substituted samples have a sintering temperature about 200°C lower than that of the sample with Co–Ti substitution only. Moreover, Bi substitution remarkably improves the soft magnetic properties in very high frequency (VHF). With the aid of Bi–Co–Ti substitution, proper Fe3+ deficiency decreases the sintering temperature by enhancing the mass transfer in solid phase. Among them, the x=0.15, y=0.75 sample can be sintered well at 950°C with high density of 5.0g/cm3, and be of the best magnetic property with both high permeability of 25 and high cut-off frequency of 480MHz, which well facilitates the VHF applications. [ABSTRACT FROM AUTHOR]

Abstract: In this paper Zn2+, Co2+, Fe3+ and La3+ were respectively introduced into Mg3Al1 mixed oxides to prepare Mg1Zn2Al1, Mg1Co2Al1, Mg3Al0.6Fe0.4 and Mg3Al0.6La0.4 oxides by calcinations at 773K. The XRD, XPS, BET, ICP-AES and CO2-TPD characterizations of samples exhibited that the effects of the substitution of trivalent cations (Fe3+, La3+) for Al3+ on the basicity of samples were stronger than the substitution of divalent cations (Zn2+, Co2+) for Mg2+ because of high O2− concentration which were coincident with the FAME yield for these catalysts. La3+ modified catalyst exhibited highest activity in transesterification. [Copyright &y& Elsevier]

Abstract: Water-soluble cationic calixarenes readily form aggregates in water. The properties of these aggregates, however, markedly vary along with alterations in the molecular structure. In a set of our recent studies, such aggregates were examined by various methods, and first of all using acid–base indicator dyes. The latter acted in fact as monoprotic acids exhibiting one color transition, and their pK a shifts against the values in water were relatively close for different calixarenes. In the present paper, we report the behavior of a much more complicated dye, fluorescein, and two relative compounds, in aqueous solutions of two cationic calix[4]arenes. The last named possess four choline groups on the upper rim and the sole difference is the length of the alkoxy groups at the lower rim: O(CH2)2CH3 and O(CH2)7CH3. In water, both calixarenes form aggregates of similar size and with similar zeta-potential. However, their influence on the acid–base and tautomeric equilibria of fluorescein clearly demonstrate that the aggregates of the long-tailed calixarene resemble the common micelles of colloidal surfactants to a higher degree than those of tetrapropyloxy compound. [Copyright &y& Elsevier]

Abstract: Since early times, dyes derived from natural sources have emerged as an important alternative to synthetic dyes. Therefore, there is a need to develop new techniques of leaching natural colorants from plant materials for dyeing applications. The present paper investigates an eco-friendly dyeing process of cotton with the aqueous extract of Hibiscus mutabilis (Gulzuba) without metal salts. During this process, the dyeing step was carried out on modified cotton by several cationizing agents in order to improve its dyeability. Cationized cotton fibres were characterized by Fourier transform infrared (FTIR) spectra and the scanning electron microscope (SEM) images. The effect of the main operating conditions (pH of the dye bath, temperature, dyeing duration, cationizing agent nature and concentration) on the dyeing quality resulted has been studied. Then, the optimization of the dyeing process was released using a response surface methodology. The performances of this dyeing process were evaluated by measuring the colour yield (K/S) of the modified cotton. It was found that cationizing cotton improves the dyeing quality and the fastness properties. [Copyright &y& Elsevier]

Abstract: Na+ is a likely intrinsic impurity in water and is a potential cation impurity in the solid polymer electrolyte water electrolysis. In this paper, the dynamic-state effect of low concentration of Na+ is studied by adding Na+ into the deionized water fed in the SPE water electrolyser. The dynamic variation of cell voltage results show that the cell performance degraded more severely in the presence of Na+ impurity by anode poisoning than by cathode poisoning. The severity and poisoning rate of the cell depend on the Na+ concentration, water flow rate and cell temperature. However, the current density does not impact the extent of the cell voltage increase. In the meantime, an external reference electrode is used to measure the anode and cathode potentials. The performance degradation is mainly ascribed to the increase in cathode overpotential by anode poisoning. EIS measurements show that the performance difference primarily comes from the kinetics loss rather than the ohmic loss. The decrease of available protons in the three phase boundaries may lead to the increase in charge transfer resistance. The electron probe microanalysis tests show that Na+ remains in CCM even recovered with deionized water, which results in only partially recovered cell performance. [Copyright &y& Elsevier]

Abstract: The material known as 1-butyl-3-methylimidazolium hydroxide has been reported to be a 1:1 mixture of [BMIM]-cations and [OH]-anions and, as such, has been widely cited as a basic ionic liquid. 1,3-Disubstituted imidazolium-cations however, are prone to deprotonation at the C2-position of the imidazolium ring, a property readily exploited for the preparation of N-heterocyclic carbenes. Consequently, this reactivity may be unexpected and especially unwelcome when it leads to the decomposition of “[BMIM][OH]” itself, especially if the decomposition occurs during its use as a basic catalyst or reaction medium. Here, we highlight the putative “[BMIM][OH]”, as a case of particular inconsistency and inaccuracy in the literature and aim to dispel some of the persisting confusion surrounding its preparation, characterisation and use. The first part of this paper concerns the history, preparation and identity of so-called “[BMIM][OH]”, whilst the second part highlights some of the claimed activity, effects and problems associated with its use. Despite warnings in the literature, reports are still appearing in which mechanistic interpretations of reaction pathways and results are made without consideration of the unwanted reactivities of the 1,3-disubstituted imidazolium-cations employed. Future publications in which the use of “[BMIM][OH]” is reported should take into account the acidity of the [BMIM]-cation and the consequences this has for the chemistry being studied. [Copyright &y& Elsevier]

Abstract: In this paper, monovalent cation Li1+ co-doped Lu0.79− x Sc0.2Ce0.01Li x BO3 (x =0, 0.005, 0.01, 0.03, 0.05) polycrystal samples were prepared and a series of methods (such as X-ray excited luminescence, diffuse reflectance, fluorescence decay, X-ray Absorption Near Edge Structure (XANES), thermoluminescence, photoluminescence emission and excitation spectra) was used to comprehensively investigate its co-doping effects. It was found that Li co-doping may play a negative role: introducing more point defects and additional color centers (such as Ce4+ and oxygen vacancy). Furthermore, the increase in the number of traps in the vicinity of luminescence center Ce3+ ions will induce the competition absorption of excitation energy with the luminescence centers, and hence deteriorate the luminescence properties. [Copyright &y& Elsevier]

Abstract: It is the purpose of this paper to determine the volumetric properties of some ionic liquids (ILs) using the modified version of Tao–Mason (TM) equation of state (EOS). The studied ILs include the cations: imidazolium, phosphonium, pyridinium, pyrrolidium and anions: tetrafluoroborate, bis(trifluoromethylsulfonyl) imide, and hexafluorophosphate. The densities of these compounds were calculated by the usage of the modified TM EOS at several temperatures and pressures. The most important parameter in this EOS is the second virial coefficient which is calculated from a two-parameter corresponding states correlation along with two constants enthalpy of vaporization and molar density both at 298K. The other remaining parameters (i.e., α(T) and b(T)) that appeared in the EOS were calculated from simple equations. Novelty of this work is the modification of the original TM EOS and usage of enthalpy of vaporization and molar density instead of critical and Boyle parameters in the original TM EOS. The good harmony between the calculated and literature density values of ILs confirms the ability of the modified TM EOS in predicting volumetric properties of this class of fluids. Overall average absolute deviation (AAD) of the calculated densities from 3394 experimental data points is 1.48%. [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cells based on nano-porous TiO2 photo-anode and quasi-solid polymer (or gel) electrolytes are emerging as low cost alternatives to conventional inorganic photovoltaic devices. Although many attempts have been made in order to improve the relatively low power conversion efficiencies of these solar cells, to our knowledge there are very few reports aimed at using a binary system of two different iodide salts toward efficiency enhancement in these cells. In this paper we report for the first time in detail, the effect of using a binary iodide salt mixture with different size cations on the efficiency enhancement in dye sensitized solar cells with polyacrylonitrile (PAN) based gel polymer electrolyte and suggest a possible mechanism for this enhancement, based on short circuit photocurrent which is directly related to the iodide ion concentration [I−]. The gel electrolyte was made of PAN, ethelene carbonate (EC), Propylene carbonate (PC), salt mixture and I2. The binary iodide salt mixture consists of potassium iodide (KI) and Tetra propyl ammonium iodide (Pr4NI). Although the gel electrolyte with 100% (w/w) KI exhibited the highest overall ionic conductivity at room temperature, it showed the lowest iodide ion (I−) contribution to conductivity. On the other hand, the electrolyte with 100% (w/w) Pr4NI exhibited the lowest overall ionic conductivity but had the highest iodide ion(I−) contribution. The dye-sensitized solar cells of configuration Glass/FTO/TiO2/N-719 Dye/electrolyte/Pt/FTO/glass were fabricated using the gel electrolytes of different salt ratios and with nanoporous TiO2 electrode sensitized with Ruthenium dye (N719). With identical electrolyte compositions, the solar cell with 100% (w/w) KI showed an efficiency of 4.98% and the cell with 100% (w/w) Pr4NI showed an efficiency of 4.47%. However, the cell with the mixed iodide system, 16.6% (w/w) KI+83.4%(w/w) Pr4NI showed the highest efficiency of 5.36% with maximum short circuit current density (J sc ) of 13.79mAcm−2, open circuit voltage (V oc ) of 679.10mV and a fill factor of 57.25%. The variation of efficiency (η) with iodide ion concentration [I−] follows the same trend as the J SC which appears to be governed by the iodide ion conductivity of the gel electrolyte. The dependence of the short circuit photocurrent and the open circuit photovoltage on the cation type generally agrees with reported data for related systems. However, the occurrence of a maximum in the solar cell efficiency and short circuit photocurrent at 16.6% (w/w) KI+83.4% (w/w) Pr4NI salt composition is an important finding. The efficiency enhancement of about 8% achieved by employing the binary iodide mixture in the gel electrolyte instead of a single iodide salt, could be utilized for achieving efficiency enhancement in many dye sensitized solar cell systems based on polymeric, gel or solvent electrolytes. [Copyright &y& Elsevier]

Abstract: Surface charges of particles together with the adsorbed counter ions in diffuse layer can set up a strong electrostatic field around the particles in aqueous solution. The existent kinetic models for describing cation exchange on solid/liquid interface were either empirical or semi-empirical, and in which the electrostatic field is not considered. In this paper, as considering the important effect of electrostatic field around particles on cations adsorption/desorption, for the first time the dynamic distribution equations of cations in diffuse layer for adsorption and desorption processes in both flow method and batch technique have been established. Those equations clearly show how the cation concentration changes with time in different position of diffuse layer during the cation exchange process, and the corresponding new kinetic models have been obtained upon them. The new models indicate that, in both flow method and batch technique, for the adsorption process, experimental results should appear zero order kinetic process caused by the strong force adsorption in the initial stage of adsorption, and then transform to the first order kinetic process of the weak force adsorption; and for the desorption process, however, only first order kinetic process may exist. The new models are essentially different from the classic apparent or empirical kinetic models since all the parameters have their defined physical meanings in the new models, thus the rate parameters in the new models have the potential to theoretically predict. Theoretical analyses also indicated that, the adsorption/desorption rate in flow method experiment will be much higher than that in batch technique experiment. [Copyright &y& Elsevier]

Abstract: This paper describes the spontaneous formation of well-defined pores in planar lipid bilayers from the self-assembly of a small synthetic molecule that contains a benzothiazole aniline (BTA) group attached to a tetra-ethylene glycol (EG4) moiety. Macroscopic and single-channel current recordings suggest that these pores are formed by the assembly of four BTA-EG4 monomers with an open pore diameter that appears similar to the one of gramicidin pores (~0.4nm). The single-channel conductance of these pores is modulated by the pH of the electrolyte and has a minimum at pH ~3. Self-assembled pores from BTA-EG4 are selective for monovalent cations and have long open channel lifetimes on the order of seconds. BTA-EG4 monomers in these pores appear to be arranged symmetrically across both leaflets of the bilayer, and spectroscopy studies suggest that the fluorescent BTA group is localized inside the lipid bilayers. In terms of biological activity, BTA-EG4 molecules inhibited growth of gram-positive Bacillus subtilis bacteria (IC50 ~50μM) and human neuroblastoma SH-SY5Y cells (IC50 ~60μM), while they were not toxic to gram-negative Escherichia coli bacteria at a concentration up to 500μM. Based on these properties, this drug-like, synthetic, pore-forming molecule with a molecular weight below 500gmol−1 might be appealing as a starting material for development of antibiotics or membrane-permeating moieties for drug delivery. From a biophysical point of view, long-lived, well-defined ion-selective pores from BTA-EG4 molecules offer an example of a self-assembled synthetic supramolecule with biological function. [Copyright &y& Elsevier]