Organofluorine chemistry is a research field of rapid expansion. Due to the unique properties of the fluorine atom and the fluorinated residues, innovation is required to push forward the boundaries of this very active research field by expanding the toolbox for emerging fluorinated groups. In this account, an overview of our recent journey in organofluorine chemistry is provided from the design of CF2FG- and SCF2FG-containing reagents to their applications in unprecedented transformations.
F.J. Sánchez-Ruiz, M. Bedolla-Hernández, G. Rosano-Ortega
et al.
This article presents a computational numerical model for the simulation and analysis of quantum chemistry and Gibbs free energy theory using static (ANNS), dynamic (DANN), and chaotic neural networks (CANN). The model calculates the physical-surface mechanics of hardness, adhesion, and strength. They resulted in nanostructured metal coatings with electrodeposited chromium nanoparticles on low-carbon steel. The ANNS, DANN, and CANN simulations showed that model-obtained values for analyzed properties presented an approximation of 99 % concerning theoretical matters taken as base. Likewise, model accuracy was verified by comparison with reference data (datasheet). The proposed model is not limited to the analyzed case and provides consistent results for predicting surface physical-mechanical properties of electrodeposited coating-substrate arrangements, with a minimum error percentage of 1–1.5 % over learning.
Materials of engineering and construction. Mechanics of materials
The G2 gas cloud motion data and the scarcity of observations on the event horizon-scale distances have challenged the comprehensiveness of the central supermassive black hole model. In addition, the recent Planck Legacy 2018 release has confirmed the existence of an enhanced lensing amplitude in the cosmic microwave background power spectra, which prefers a positively curved early Universe with a confidence level higher than 99%. This study investigates the impact of the background curvature and its evolution over conformal time on the formation and morphological evolution of central compact objects and the consequent effect on their host galaxies. The formation of a galaxy from the collapse of a supermassive gas cloud in the early Universe is modelled based on interaction field equations as a 4D relativistic cloud-world that flows and spins through a 4D conformal bulk of a primordial positive curvature considering the preference of the Planck release. Owing to the curved background, the derived model reveal that the galaxy and its core are formed at the same process by undergoing a forced vortex formation with a central event horizon leading to opposite vortices (traversable wormholes) that spatially shrink while evolving in the conformal time. The model shows that the accretion flow into the supermassive compact objects only occurs at the central event horizon of the two opposite vortices while their other ends eject relativistic jets. The simulation of the early bulk curvature evolution into the present spatial flatness demonstrated the fast orbital speed of outer stars owing to external fields exerted on galaxies. Furthermore, the gravitational potential of the early curved bulk contributes to galaxy formation while the present spatial flatness deprives the bulk potential which can contribute to galaxy quenching. Accordingly, the model can explain the relativistic jet generation and the G2 gas cloud motion if its orbit is around one of the vortices but at a distance from the central event horizon. Finally, the formation of a galaxy and its core simultaneously could elucidate the growth of the supermassive compact galaxy cores to a mass of ~10<sup>9</sup> <i>M</i><sub>⊙</sub> at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≤</mo><mn>6</mn><mo>%</mo></mrow></semantics></math></inline-formula> of the current Universe age.
Mechanical drawing. Engineering graphics, Physical and theoretical chemistry
In this article, we prepared novel basalt fiber (BF)-reinforced polypropylene (PP) composites based on the synergistic reinforcement of cellulose nanocrystals (CNCs). First, we compared the enhancement effect of CNCs and silane coupling agent-modified BFs on PP, showing that the enhancement effect of the former was more significant. Subsequently, to further improve the mechanical properties of the composites, CNCs were introduced into the BF-reinforced PP composite system as the third phase, and the results suggested that their combination with BFs could synergistically strengthen the PP matrix composites. Simultaneously, the study also shows that when the mass percentage of CNCs and BFs are 1 and 30%, respectively, the composite achieves the highest mechanical strength, which is 64.31% higher than that of the PP matrix. The systematic characterization revealed the synergistic enhancement mechanism: on the one hand, CNCs not only promoted the improvement of PP crystallinity by heterogeneous nucleation but also formed a wedge-shaped structure between them and BFs through hydrogen bonding to prevent PP molecular movement; on the other hand, the BFs promote not only the extrusion crystallization of the resin matrix but also the network structure formed by the appropriate content of BFs can realize the rapid transmission of external stress.
This investigation describes an efficient method for the synthesis of unsymmetrical N-aryl bis(indolyl)methanes by C–N cross-coupling reaction of unsubstituted bis(indolyl)methanes with aryl iodides in the presence of several Cu salts and CuFe$_{2}$O$_{4}$ as homogeneous and heterogeneous catalysts, respectively. Among these Cu containing catalysts, CuFe$_{2}$O$_{4}$ under ligand-free conditions showed the best activity and selectivity for mono N-arylation of bis(indolyl)methanes. Notably, CuFe$_{2}$O$_{4}$ catalyst was recovered and reused several times.
A novel trichlofon biosensor is a carbon (3D-EUS) sensor prepared from AChE 3D porous Eucommia ulmoides (inner stem behind bark of eucommia ulmoides), which is a novel electrochemical biomolecular carrier material containing biological molecules proposed for the first time [1]. Here, a whole block of 3D-EUS loaded with acetylcholinesterase (AChE) molecules was used to prepare a 3D-EUS integrated electrode for trichlorfon biosensing. The morphologies of 3D-EUS and AChE/3D-EUS integrated electrodes were characterized by scanning electron microscope (SEM). And the results demonstrated that the electrode has a 3D macropore structure. The electrochemical behavior and Electrocatalytic Performance of AChE/3D-EUS integrated electrode were studied by cyclic voltammetry and differential pulse voltammetry A sensor has the advantages of good stability, low detection limit (0.069 ng/mL) wide linear range (0.20-18 ng/mL), it can be used as an important platform for field detection of pesticide residues.
Industrial electrochemistry, Physical and theoretical chemistry
Applications of the molten salt electrodeposition method have attracted researcher’s attention in the preparation of magnesium-based alloys in the past decades. Sometimes, hot corrosion occurs on the surface of a metal electrode in molten salt. Here, the corrosion of a Ni electrode and its effect on the electrochemical formation processes of Mg-Ni alloys were studied in LiCl-KCl-MgCl2 molten salt under an Ar atmosphere. Immersion experiments and some electrochemical experiments, such as cyclic voltammetry (CV), open-circuit chronopotentiometry (OCP), and potentiostatic electrolysis, were carried out to investigate the performance of a Ni metal electrode in LiCl-KCl-MgCl2 molten salt. Hot corrosion of the Ni electrode became serious with the addition of MgCl2, and MgO was deposited on the surface of the Ni sheet. The CV and OCP experiments showed that the water introduced from outside had serious effects on the electrochemical reaction processes in this experiment. Corrosion of the Ni substrate was dynamically and thermodynamically inhibited in the electrochemical formation processes of Mg-Ni alloys. However, there was a small amount of MgO in the Mg-Ni alloys, and corrosion of the Ni sheet showed obvious effects on the morphology of Mg-Ni alloys
Industrial electrochemistry, Physical and theoretical chemistry
The electrode state changes with the thickening of the coating in Cr(III) thick chromium plating. The deposition of Cr(III) is carried out on the substrate at the beginning of deposition and on the chromium coating when the chromium coating becomes thicker. The aim of this work is to study the influence of the change of electrode state on the reduction mechanism of trivalent chromium. The electrodeposition mechanism of Cr(III) is studied by cyclic voltammetry, electrochemical impendance spectroscopy, chronoamperometry and polarization technique. The results show that the reduction of Cr(III) on chromium coating electrode has a negative deposition potential, higher charge transfer resistance, higher activation energy, and lower diffusion coefficient than those on the nickel electrode, the reduction of Cr(III) is more difficult on chromium coating electrode. The change of electrode state is one of the reasons for the difficulty in thickening of chromium coating.
Industrial electrochemistry, Physical and theoretical chemistry
Mixed ligand complexes (MC) of pyridoxine HCl drug as ligand [P] with Zn(II) in the occurrence of some bioligands (amino acids or peptides) as ligands [L] have been studied using pH-metric measurements in aqueous solution at 25 °C and ionic strength I = 0.10 mol dm-3 (NaNO3). The obtained complexes and their formation constants were established on basis of computer analysis potentiometric data, using specific program model (HYPERQUAD). Complexes mixed-ligand were formed by a simultaneous mechanism. The parameter Δlog K, log X, and % R.S. were evaluated and discussed. The determination of the pH of solutions was executed through finding the percentage of the distribution of several species.
Industrial electrochemistry, Physical and theoretical chemistry
Modification of commercial separators with conductive and active barrier layers towards soluble polysulfides is an effective way to combat the shuttle effect and improve the utilization rate of sulfur in lithium-sulfur (Li-S) batteries. Herein, well-dispersed amorphous Ta2O5 was chemically grafted onto oxidized multi-walled carbon nanotubes (CNT-O) under mild conditions by a one-pot solvent evaporation method. The prepared Ta2O5/CNT-O composite was used as a modified separator layer in a Li-S battery, which combined the advantages of the intertwined structure of conductive CNT-O and the chemisorption ability of Ta2O5. Cyclic voltammetry (CV) curves and X-ray photoelectron spectroscopy (XPS) verified the catalytic effect of Ta2O5 on the redox reactions during the discharge/charge processes and the strong chemical interactions between polysulfides and Ta2O5. Scanning electron microscopy (SEM) images of the modified separators after cycling revealed that the well-dispersed amorphous Ta2O5 could immobilize soluble polysulfides through chemical interactions and prevent aggregation of the insoluble products (Li2S2, LiS2 and S8) during the redox reactions, leading to a uniform redistribution of the sulfur species inside the modification layer, which could ensure the conductivity of the modification layer and high utilization rate of sulfur during long-term cycling processes. A Li-S cell prepared with Ta2O5/CNT-O modified separator exhibited a high initial specific capacity of 1230.7 mAh/g at a current density of 0.2 C and stable cycle performance with a decay rate of only 0.11% per cycle over 500 discharge/charge cycles.
Industrial electrochemistry, Physical and theoretical chemistry
One-dimensional ZnO nanowires/ferrocenyl-alkanethiol array is synthesized on silicon substrate combined by self-assembled and low temperature aqueous methods. Electro-catalytic responses of glucose oxidase/ ZnO nanowires/ferrocenyl-alkanethiol array/Silicon (GOx/ZnO NWs/FcC11SH/Si) electrode are detected deeply. The ZnO nanowires/ferrocenyl-alkanethiol array has provided a favorable environment to the immobilization of glucose oxidase. The morphology and crystal structure of the as-grown products have been characterized by many methods, including scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical test. Electrochemical results demonstrated that the well configuration GOx/ZnO NWs/FcC11SH/Si possessed excellent electrocatalytic activity to glucose, which provide a meaningful way for the practical applications in clinical, environmental, and food analysis.
Industrial electrochemistry, Physical and theoretical chemistry
A modified emulsion polymerisation synthesis route for preparing highly dispersed cationic polystyrene (PS) nanoparticles is reported. The combined use of 2,2′-azobis[2-(2-imidazolin- 2-yl)propane] di-hydrochloride (VA-044) as the initiator and acetone/water as the solvent medium afforded successful synthesis of cationic PS particles as small as 31 nm in diameter. A formation mechanism for the preparation of PS nanoparticles was proposed, whereby the occurrence of rapid acetone diffusion caused spontaneous rupture of emulsion droplets into smaller droplets. Additionally, acetone helped to reduce the surface tension and increase the solubility of styrene, thus inhibiting aggregation and coagulation among the particles. In contrast, VA-044 initiator could effectively regulate the stability of the PS nanoparticles including both the surface charge and size. Other reaction parameters i.e. VA-044 concentration and reaction time were examined to establish the optimum polymerisation conditions.
Physical and theoretical chemistry, Chemical technology
Corrosion and cavitation erosion behaviors of the cast and friction stir processed (FSP) Ni-Al bronze (NAB) in sulfide-containing (polluted) 3.5% NaCl solution were investigated in the present study. The electrochemical impedance spectroscopy (EIS) results demonstrated that the corrosion product film formed in the polluted solution was of poor protectiveness, and the gravimetric measurements results indicated that the sulfide ions increased the corrosion rate by a factor of 1.13 for the cast and 2.12 for the FSP NAB, compared with the results in clean 3.5% NaCl solution. The sulfide ions promoted the formation of a thick and porous corrosion product film, which consisted of sulfides and oxides. Deep pits were found propagated along the eutectoid microstructure for the cast and the β’ phases for the FSP NAB. The cavitation erosion mass loss with the addition of sulfide was 0.92 times and 2.52 times more than that in the clean solution for the cast and FSP, respectively. The increased corrosion damage induced by the sulfide ions deteriorated the mechanical properties and consequently accelerated the cavitation erosion degradation. The corrosion-cavitation erosion synergy/total mass loss (i.e. S/T) value in the polluted solution reached 73.48% for the cast and 76.94% for the FSP. It can be seen that the FSP NAB exhibited no obvious superiority in the corrosion and cavitation erosion resistance, compared with the cast one in the sulfide-containing chloride solution.
Industrial electrochemistry, Physical and theoretical chemistry
Mirha Pazalja, Emira Kahrović, Adnan Zahirović
et al.
A new low potential electrochemical sensor for determination of L-cysteine based on carbon electrodes modified with Ru(III) Schiff base complex, multi-walled carbon nanotubes and Nafion is presented. Cyclic voltammetry, differential pulse voltammetry and flow injection analysis were employed. Measurements were carried out using Britton-Robinson buffer (pH 5.50). The results showed that addition of multi-walled carbon nanotubes to Ru(III) complex modified glassy carbon and screen printed carbon electrodes gives increased current signals at the potential where oxidation of L-cysteine occurs. Flow injection amperometric measurements were performed at the operating potential +0.15 V vs. Ag/AgCl (3 M KCl) electrode and showed fast electric current response for L-cysteine oxidation, demonstrating good reproducibility and stability. The sensor has a detection limit of 0.11 mg L-1 and a dynamic range of 50-500 mg L-1. The repeatability was calculated as 2.8 %. New sensor was used for the determination of L-cysteine in pharmaceutical products.
Industrial electrochemistry, Physical and theoretical chemistry
Ali Mohammed Alsalme, Abdulaziz Ali B. Alghamdi, Ammar Abdul Ghani Q. Alhamdani
et al.
Three vinylene-benzothiadiazole based alternating copolymers with carbazole, 3,6-difluoro carbazole and fluorene were prepared via Suzuki coupling polymerisation in the presence of catalytic amounts of palladium (II) acetate Pd(OAc)2 and tri-ortho-tolylphosphine. P(o-tol)3. The molecular weights measured by gel permeation chromatography and copolymers were characterised by NMR, UV-Vis spectroscopy and cyclic voltammetry. The physical properties and their band gaps are discussed in relation with their donor units (carbazole and fluorene derivatives).
Industrial electrochemistry, Physical and theoretical chemistry
Determination of iron(III) in N-methyldiethanolamine activated by piperazine (a-MDEA) utilized in sweetening plant of gas treating industry is described by preparation of gold 2-mercaptosuccinic acid self-assembled monolayer electrode and characterized by cyclic voltammetry and square wave voltammetry methods. The square wave voltammograms showed a sharp peak around positive potentials +0.180 V that was used for construction of the calibration curve. Factors were optimized for iron(III) stripping analysis and optimal condition was frequency of 35 Hz, step potential of 14 mV, amplitude of 40 mV, pH =3, and preconcentration time of 10 min. A calibration curve was obtained for iron(III) in a-MDEA in a linear range of 1.25 × 10-6 to 2.69 ×10-5 mol L-1. The detection limit was found to be 1.94 × 10-7 mol L-1. The relative standard deviation (RSD) of 3.29 % for n = 6 at 1.79 × 10-5 mol L-1 iron(III) in a-MDEA media was observed in the best conditions. The presented procedure was successfully applied for determination of iron(III) content in the real samples from sweetening plant of gas treating industry.
Industrial electrochemistry, Physical and theoretical chemistry
In this study, the pretreated glassy carbon electrode (GCE) was prepared by electrochemical oxidation firstly at +1.75 V for 300 s, and then by electrochemical reduction at –1.75 V for 300 s in 0.1 mol L–1 pH 7.0 phosphate buffer solution (PBS) and used for the determination of dopamine (DA) by cyclic voltammetry (CV). The pretreated GCE gives 100-fold greater current responses for dopamine compared with unpretreated GCE. The effect of pH, pretreated mode, scan rate and concentration of dopamine on the peak current was investigated, and the results indicated that the peak current of dopamine is the highest in 0.1 mol L–1 pH 7.0 PBS and the electrode reaction corresponds to a rate-controlled process. The peak current of the anodic peak and the concentration of dopamine hydrochloride is linear in the range of 1.0 × 10–7 – 9.0 × 10–6 mol L–1 and 1.2 × 10–5 – 8.0 × 10–5 mol L–1 with correlation coefficients of 0.9973 and 0.9980, and the detection limit is 3.0 × 10–8 mol/L. It has been successfully applied to the determination of dopamine in dopamine hydrochloride injection with recoveries ranging from 98 to 103%. The proposed method possesses the distinct advantages of simple, appropriate for operation, good reproducibility and cheap instrument.
Industrial electrochemistry, Physical and theoretical chemistry
Amorphous TiO2 nanoparticles are synthesized by microemulsion method using cetyltrimethylammonium bromide (CTAB) as dispersant for the first time, and then they are used to synthesize the Li4Ti5O12/C composite by a simple solid-state method. The amorphous TiO2 nanoparticles have high reaction activity with Li2CO3 to promote the synthesis of Li4Ti5O12/C composite at lower temperature and shorter time. The grain size of prepared Li4Ti5O12/C composite with different carbon additions is less than 400 nm. The Li4Ti5O12/C composite shows high specific capacity and very long cycling life. The specific capacities of the Li4Ti5O12/C composite with 5% carbon addition at 0.1, 1 and 5 C rates are 162.4, 147.4 and 114.9 mAhg-1, respectively, and its capacity retention after 600 cycles at 1 and 5 C rates is respective 99.86% and 92.95%. The synthesis method can be used for a mass production of Li4Ti5O12/C composite in industry.
Industrial electrochemistry, Physical and theoretical chemistry
Tsung-Hsuan Tsai, Tse-Wei Chen, Shen-Ming Chen
et al.
The conducting polymer (PEDOT) modified electrode was used to investigate the formation of copper(II) hexacyanoferrate by adjusting molar ratio of ferricyanide and copper(II) chloride with 20 scan cycles of 0 – 1 V. Three film types of copper(II) hexacyanoferrate/PEDOT have been successfully prepared and discussed using PEDOT film modified electrodes in [K3Fe(CN)6]:[CuCl2] = 1:1, 1:5, and 1:10, respectively. The copper(II) hexacyanoferrate/PEDOT films exhibit significant voltammograms and can be classified from Type I to Type III due to their different CuHCF content. All of these films exhibit specific fiber-like structure due to the doping of ferricyanide and copper(II) hexacyanoferrate on PEDOT surface. Furthermore, these films could simultaneously determine AA and AP. Particularly, the film with higher CuHCF content could provide much higher sensitivity. The current response can be expressed as Ipa1(μA) = 25.93[AA](mM) + 147.2 (R2 = 0.9946) and Ipa2(μA) = 19.79[AP](mM) + 189.6 (R2 = 0.9972). The linear range is found in 0.18–1.8x10−2 M and 0.16–1.6x10−2 M for AA and AP, respectively.
Industrial electrochemistry, Physical and theoretical chemistry