Type Of Cation Research Articles

Divalent cations in human liver pyruvate kinase exemplify the combined effects of complex-equilibrium and allosteric regulation

There is growing recognition that the functional outcome of binding of an allosteric regulator to a protein/enzyme is influenced by the presence of other ligands. Here, this complexity is exemplified in the allosteric regulation of human liver pyruvate kinase (hLPYK) that is influenced by the presence of a range of divalent cation types and concentrations. For this system, fructose-1,6-bisphosphate (activator) and alanine (inhibitor) both influence the protein’s affinity for the substrate, phosphoenolpyruvate (PEP). Mg2+, Mn2+, Ni2+, and Co2+ were the primary divalent cations evaluated, although Zn2+, Cd2+, V2+, Pb2+, Fe2+, and Cu2+also supported activity. Allosteric coupling between Fru-1,6-BP and PEP and between Ala and PEP varied depending on divalent cation type and concentration. Due to complicating interactions among small molecules, we did not attempt the fitting of response trends and instead we discuss a range of potential mechanisms that may explain those observed trends. Specifically, observed “substrate inhibition” may result from substrate A in one active site acting as an allosteric regulator for the affinity for substrate B in a second active site of a multimer. We also discuss apparent changes in allosteric coupling that can result from a sub-saturating concentration of a third allosteric ligand.

Experimental analysis of the impact of ionic concentration and type on shale’s stability: dilute vs. concentrated salt solutions

ABSTRACT Wellbore instability in shale formations is one of the most bothersome problems leading to significant changes in shale’s petrophysical, mechanical, and chemical properties, and could cost billions of dollars annually. Drilling fluid’s ionic composition is one of the factors affecting wellbore stability. This paper investigates the impact of chemical osmosis, ionic diffusion, and diffusion osmosis on the stability of shale, identify the critical salt concentration, and examine the impact of ionic type and concentration on shale’s stability. Experimental methods include utilisation of two different shale cores (I and II), in which each core is cut into several samples, to conduct linear expansion and gravimetric measurement tests using different salt solutions (KCl, NaCl, and CaCl2) of various salt concentrations. Results show that the critical salt concentrations of shale I and II is 8 w/w%. Chemical osmosis is found to be a reliable method for water extraction out of shale if the critical salt concentration value is not surpassed. Beyond this value, ionic diffusion and diffusion osmosis in shale I and II were adversely affecting shale’s stability through swelling. The swelling and gravimetric ions and water uptake tests showed that shale is a leaky semi-permeable membrane, and that chemical osmosis could be jeopardised by ionic transport into shale. In this study, the cation type (Na+, K+, Ca+2) that makes up the salt was varied. The impact of cation type on the stability of shale was clear as the anion type was fixed. Since both cations and anions tend to diffuse into shale in the presence of a concentration gradient, it is proposed for future work to study the combined impact of cation and anion types on shale’s stability by varying the anion and cation types.

Yb Substitution and Ultralow Thermal Conductivity of the Ca3–xYbxAlSb3 (0 ≤ x ≤ 0.81(1)) System

A series of Yb-substituted Zintl phases in the Ca3-xYbxAlSb3 (0 ≤ x ≤ 0.81(1)) system has been synthesized by initial arc melting and post-heat treatment, and their isotypic crystal structures were characterized by both powder and single crystal X-ray diffraction analysis. All four title compounds adopted the Ca3AlAs3-type structure (space group Pnma, Pearson code oP28, Z = 4). The overall structure can be described as a combination of the 1-dimensional (1D) infinite chain of ∞1[Al(Sb2Sb2/2)] formed by two vertices sharing [AlSb4] tetrahedral moieties and three Ca2+/Yb2+ mixed sites located in between these 1D chains. The charge balance and the resultant independency of the 1D chains in the title system were explained by the Zintl-Klemm formalism [Ca2+/Yb2+]3[(4b-Al1-)(1b-Sb2-)2(2b-Sb1-)2/2]. A series of DFT calculations proved that (1) the band overlap between the d-orbital states from two types of cations and the p-orbital states from Sb at the high symmetry Γ point implied a heavily doped degenerate semiconducting behavior of the quaternary Ca2YbAlSb3 model and (2) the site preference of Yb for the M1 site was due to the electronic-factor criterion based on the Q values of each atomic site. The electron localization function calculations also proved that the two different shapes of lone pairs of the Sb atoms─the "umbrella-shape" and the "C-shape"─are determined by local geometry and the coordination environment on the anionic frameworks. Thermoelectric measurements of the quaternary title compound Ca2.19(1)Yb0.81AlSb3 showed an approximately two times larger ZT value than that of ternary Ca3AlSb3 at 623 K due to increased electrical conductivity and ultralow thermal conductivity originated from Yb substitution for Ca.

Crystal engineering regulation achieving inverse temperature symmetry breaking ferroelasticity in a cationic displacement type hybrid perovskite system

Ferroelastic hybrid perovskite materials have been revealed the significance in the applications of switches, sensors, actuators, etc. However, it remains a challenge to design high-temperature ferroelastic to meet the requirements for the practical applications. Herein, we reported an one-dimensional organic-inorganic hybrid perovskites (OIHP) (3-methylpyrazolium)CdCl3 (3-MBCC), which possesses a mmmF2/m ferroelastic phase transition at 263 K. Moreover, utilizing crystal engineering, we replace ‒CH3 with ‒NH2 and ‒H, which increases the intermolecular force between organic cations and inorganic frameworks. The phase transition temperature of (3-aminopyrazolium)CdCl3 (3-ABCC), and (pyrazolium)CdCl3 (BCC) increased by 73 K and 10 K, respectively. Particularly, BCC undergoes an unconventional inverse temperature symmetry breaking (ISTB) ferroelastic phase transition around 273 K. Differently, it transforms from a high symmetry low-temperature paraelastic phase (point group 2/m) to a low symmetry high-temperature ferroelastic phase (point group 1¯) originating from the rare mechanism of displacement of organic cations phase transition. It means that crystal BCC retains in ferroelastic phase above 273 K until melting point (446 K). Furthermore, characteristic ferroelastic domain patterns on crystal BCC are confirmed with polarized optical microscopy. Our study enriches the molecular mechanism of ferroelastics in the family of organic-inorganic hybrids and opens up a new avenue for exploring high-temperature ferroic materials.

Low-, medium-, and high-entropy pyrochlores in (Bi,Li,Na,La,Eu)1.9(Mg0.5Nb1.5)O7-δ compositions, their optical and dielectric properties

The pyrochlore phase formation in the (Bi,Li,Na,La,Eu)1.9(Mg0.5Nb1.5)O7-δ compositions with different element fractions in the A sites of the A2B2O6O' structure was studied. The low- and medium-entropy pyrochlores were formed after calcination of the batch at 1000–1150 °C. The high-entropy pyrochlore composition was detected during the investigations. Its stability by ab initio calculation was proven. The main impurities (Eu0.55La0.35Bi0.04)NbO4-δ and Na0.65MxNbO3-δ were identified in the initial medium- and high-entropy compositions as more stable phases. The samples belong to wide band gap semiconductors (Egdir = 3.2–3.6 eV, Egindir = 2.9–3.0 eV). The dielectric parameters calculated from impedance spectra depend on polarizability created by different types of cations in the A2O' sublattice. The dielectric permittivity (ε' = 67–162, at 25 °C and 1 MHz) decreases with decreasing polarizability of the system, while the tangent loss remains equally low (tanδ = 0.002–0.003 up to 240 °C). The presence of impurity phases in the initial high-entropy pyrochlores adversely affected the dielectric properties. Two mechanisms of conductivity were distinguished.

Ionic liquid – grafted mesoporous silica exhibiting reverse selectivity for ethane/ethylene separation

Development of paraffin-selective adsorbents for the separation of ethane/ethylene mixtures, as an alternative technology to the energy-intensive cryogenic distillation, is challenging. Herein, we report surface-functionalized mesoporous silica adsorbents exhibiting reverse selectivity prepared by controlled in-situ synthesis of paraffin-selective ionic liquids (ILs) onto the pre-silanized surface of MCM-41 mesoporous silica. The surface modification switched the selectivity of the adsorbents from being inherently olefin-selective to becoming paraffin-selective, due to the enhanced van der Waal’s interactions between the grafted IL functionalities and the ethane molecules. A range of silica-based adsorbents functionalized with ILs of different loadings and anion and cation types were synthesized, characterized and investigated for their ethane/ethylene adsorption behavior. In addition to reversing the selectivity yielding values of up to 3.4 for ethane over ethylene, the adsorbents exhibited low isosteric heat of adsorption, indicatively 12 kJ/mol for ethane, while their performance was stable upon pressure swing adsorption and breakthrough cyclic testing. Dynamic packed bed experiments with ethane/ethylene mixtures demonstrated a breakthrough ethylene productivity of up to 1.2 mmol/g with a breakthrough selectivity of 2.4.

OBTAINING, PROPERTIES, AND PROSPECTS FOR USE OF Al30-PILLARED MONTMORILLONITE

Over the past decade, the Department of Technology of Ceramics and Electrochemical Production has been conducting research related to the obtaining of new types of refractory non-metallic and silicate materials. One of the promising directions is focused on the modification of natural clay minerals in order to enhance their sorption, catalytic, electrolytic, optical and other properties. This article presents the results on the functionalization of pillared clays. Using the "giant" aluminum polycations [Al30O8(OH)56(H2O)24]18+, Al30-pillared montmorillonite (Al30-PMM) was obtained for the first time by the intercalation method, its structural and textural properties were characterized, and its functionality was studied. When identifying Al30 polycations and studying the physicochemical properties of Al30-PMM in comparison with the previously known Al13-PMM and the original natural montmorillonite (Dash-Salakhly deposit, Azerbaijan), the following methods were used: photometry, infrared and fluorescence spectroscopy, electron microscopy, static light scattering, NMR spectroscopy, porosimetry, dynamic laser beam scattering, X-ray diffractometry, thermogravimetric and differential thermal analysis, impedancemetry and high-temperature mass spectrometry. The effect of preliminary mechanical activation of the aluminosilicate matrix on the efficiency of intercalation of aluminum polycations has been studied. An anomaly in the temperature dependence of the current density of the thermal emission of alkali metal ions from the Al30-PMM surface was found, interpreted from the point of view of the phase transformation of pillars. The patterns of adsorption on Al30-PMM of organic dyes of cationic and anionic types in aqueous solutions, carotenoids and fatty acids in vegetable oil, as well as humic acids, for which, in combination with Al30-PMM, the detoxifying ability with respect to oil in water was examined. A new method of electrolytic modification of montmorillonite is proposed, which consists in doping with lithium and sodium ions of nanocavities of pillared montmorillonite. It has been shown that hydrothermal cohydrolysis of aluminum and cerium salts makes it possible to synthesize large-sized polyhydroxocomplexes that improve the textural properties of pillared montmorillonite compared to Al30-PMM. In general, the fundamental principles of the formation of a layered-columnar structure identified in the work can be used to design innovative materials based on layered systems by varying the sizes and chemical composition of intercalated ions. For citation: Butman M.F., Ovchinnikov N.L., Kosenko N.F., Filatova N.V., Pogonin A.E. Obtaining, properties, and prospects for use of Al30-pillared montmorillonite. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 7. P. 159-172. DOI: 10.6060/ivkkt.20236607. 6833j.

Deciphering the specific interaction of humic acid with divalent cations at the nanoscale

Humic acid (HA), a representative class of natural organic matter (NOM), can interact with a variety of divalent cations to form the metal-HA complexes, which is of vital significance in both the natural and engineered environments. To decipher the specific HA-divalent cation interaction mechanism, the intermolecular forces and adhesion energies between two HA surfaces in aqueous environment with varying divalent cations were directly quantified at the nanoscale using atomic force microscope (AFM). In the presence of Ca2+, the considerably increased HA aggregation and HA-Ca(II)-HA adhesion were detected with elevated Ca2+ concentration mainly due to the enhanced bridging effect, while the excessive amounts of Ca2+ could significantly suppress the aggregation and adhesion behavior. The adhesion energy was also found to be dependent on other aqueous conditions (e.g., pH, cation type), with the highest adhesion energy measured for Cu2+ (∼1.642 mJ m−2), approximately 2 ∼ 3-fold higher than the case of Zn2+ (∼0.950 mJ m−2), Ca2+ (∼0.829 mJ m−2) and Mg2+ (∼0.583 mJ m−2). Such robust adhesion for Cu2+ could stem from the synergistic bonding of Cu2+ with both the oxygen and amine sites of HA, which was evidently different from the single metal–oxygen bonding for Zn2+, Ca2+ and Mg2+ shown by X-ray photoelectron spectroscopy (XPS). Based on density functional theory (DFT) simulation, HA molecules could bridge with all these four types of divalent cations mainly by the deprotonated catechol and phthalic acid (PA) structures in the bidentate coordination mode, while the deprotonated aniline could only bond with Cu2+, ultimately leading to the highest Cu(II)-HA binding energy among the studied divalent cations. This work provides insights into the quantitative understanding of HA-divalent cation interaction mechanisms, shedding light on developing effective strategies to modulate the aggregation, transport and fate of NOM in aqueous environments as well as engineering applications.

Effects of residual alkali metals on the hydrothermal/thermal stability of silicalite-1

Understanding of the main factors affecting the hydrothermal stability of zeolites is vital for the application of zeolites in catalysis and separation. Although incorporation of extra-framework metal cations is an important stagey to improve the hydrothermal stability of Al-rich zeolites, how these metal cations affect the hydrothermal stability of high-silica zeolites is not well understood. In this work, the effects of residual alkali cations on the hydrothermal/thermal stability of silicalite-1, a pure-silica MFI-type zeolite, is explored. We show that the alkali impurities from commercial tetrapropylammonium hydroxide (TPAOH) are not negligible; the concentration and type of residual alkali cations dictate the hydrothermal/thermal stability of silicalite-1. Above a certain concentration (∼0.3–0.5 wt%), the alkali cations can lead to less silanol defects but much poorer hydrothermal/thermal stability. Below this concentration, the degrading effect is negligible. Removal of the alkali cations by proton exchange improves the stability significantly. Steaming (hydrothermal treatment) has two opposite effects on the silicalite-1 crystal structure: destruction by hydrolysis and perfecting by healing the defects. For silicalite-1 with considerable amounts of alkali cations, the destruction effect predominates; while the perfecting effect predominates for silicalite-1 with low alkali contents.

Photoelectrocatalytic Surfactant Pollutant Degradation and Simultaneous Green Hydrogen Generation.

For the first time, we demonstrate a photoelectrocatalysis technique for simultaneous surfactant pollutant degradation and green hydrogen generation using mesoporous WO3/BiVO4 photoanode under simulated sunlight irradiation. The materials properties such as morphology, crystallite structure, chemical environment, optical absorbance, and bandgap energy of the WO3/BiVO4 films are examined and discussed. We have tested the anionic type (sodium 2-naphthalenesulfonate (S2NS)) and cationic type surfactants (benzyl alkyl dimethylammonium compounds (BAC-C12)) as model pollutants. A complete removal of S2NS and BAC-C12 surfactants at 60 and 90 min, respectively, by applying 1.75 V applied potential vs RHE to the circuit, under 1 sun was achieved. An interesting competitive phenomenon for photohole utilization was observed between surfactants and adsorbed water. This led to the formation of H2O2 from water alongside surfactant degradation (anode) and hydrogen evolution (cathode). No byproducts were observed after the direct photohole mediated degradation of surfactants, implying its advantage over other AOPs and biological processes. In the cathode compartment, 82.51 μmol/cm2 and 71.81 μmol/cm2 of hydrogen gas were generated during the BAC-C12 and S2NS surfactant degradation process, respectively, at 1.75 V RHE applied potential.

Method and apparatus for automatic high-throughput synthesis of energetic salts

Energetic materials can instantly combust and release a large amount of energy in responding external impulses. Due to its energy characteristics, it has a wide range of practical applications: military and civilian. Designing high-energy-density materials with better performance, lower sensitivity, and more environmental friendliness has become a hotspot in the field of energetic materials in recent years. Energetic salts are formed by acid-base or metathesis reactions of different types of anions and cations. Energetic salts are a new class of energetic materials which were developed in recent years. Usually, they have high nitrogen content, high enthalpy of formation, high detonation performance, are relative stable to external stimuli, and have a wide range of application prospects in the fields of new explosives: low characteristic signal propellants, gas generators, low smoke or smokeless pyrotechnics. The synthesis method of energetic salts is simple, and the types of energetic materials are greatly enriched. This research takes energetic salts as the synthesis target and adopts multi-channel automation technology for high-throughput synthesis, which can improve the efficiency, reduce labor costs, and greatly increase the synthesis speed, which is of great significance for accelerating the synthesis of new energetic salts.

The Use of Cationic Rapid Setting Emulsion Cold Asphalt Mixtures for Appropriate Road Rehabilitation

This study aims to determine the Optimum Residual Asphalt Content in different aggregate sources and the characteristics of Cold Emulsion Asphalt Mixture if the gradation used is the National Asphalt Pavement Association (North Carolina) gradation. The aggregates used in this study came from PT. Pancadarma Puspawira, Surakarta and The Public Work Office Magetan District with the asphalt used is cationic emulsion asphalt type CRS-2. The emulsified asphalt content used for the Magetan mixture was 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, while the emulsified asphalt content for the Pancadarma mixture was 7.5%, 8.0%, 8.5%, 9.0%, 9.5%. The parameters reviewed in this study were density, VIM, VMA, VFB, stability, flow and Marshall Quotient with reference to the 2018 Highways Specification for repair overlay. The results showed that the emulsified asphalt mixture of CRS-2 Magetan and Pancadarma did not meet the specifications for repair overlay. The optimum emulsion asphalt content that is possible in the Magetan mixture is 8.0% with KARO 5.37% (stability 269.24 kg; density 2.04 gr/cc; VIM 5.71%; MQ 65.28 kg/mm; Flow 4.31 mm; VMA 18.39%; VFB 68.95 %). While the Pancadarma mixture is 9.5% with KARO (stability 70.07 kg; density 2.22 gr/cc; VIM 4.75%; MQ 23.31 kg/mm; Flow 3.05 mm; VMA 23.79%; VFB 80.03%).

Durability of CO2-fly ash-based backfill materials in cation water deterioration

ABSTRACT This study aims to investigate the weakening of CO2-fly ash-based backfill (CFBF) material in cation water. Weakening is determined in an order of Na+ > Ca2+ > Mg2+ by slake durability and mechanical properties analysis. Na+ damages the microstructure of CFBF through the ion exchange phenomenon, causing the ejection of tetrahedral calcium. In Ca2+ and Mg2+ water, N-M-A-S-H gel is precipitated and filled in openings via a two electrical-layer mechanism, which mitigates the materials from further deterioration. On this basis, the suitable cation type and concentration range are proposed as criteria to implement CFBF in mine-water affected backfill coal mining.

Orthogonal and twisted dimers of redox-active pyrrole-fused pentaazapolycyclic hydrocarbons

Orthogonal and twisted dimers of pyrrole-fused pentaazapolycyclic hydrocarbons (pentaazacoronene analogs) were synthesized, linked either directly or by phenylenes. Although the dimers and the reference monomer did not have any substituents at the [Formula: see text]-positions of the terminal pyrroles, two reversible oxidation waves were observed in the cyclic voltammograms. ESR measurements of the chemically generated dications of the dimers showed typical radical cation signals, indicating successful accumulation of the redox activity of the pentaazacoronene analog.

Photophysical Properties of Pyrene‐Substituted nido‐Carborate Anion and the Change of Luminescence Species by Counter Cations in Solution and Solid States

AbstractThis study reports unique luminescent properties of pyrene‐substituted nido‐carborate anion (PYnCA) with two counter cations, tetrabutylammonium (NBu4+) and tetraphenylphosphonium (PPh4+). It is revealed that PYnCA shows twisted intramolecular charge transfer (TICT) emission by the change of the dihedral angle between pyrene and the CcageCcage bond in the carborane unit in the excited state. Although the structure of nCA is almost same as that of ortho‐carborane (oC), the photophysical processes of both pyrene‐substituted compounds are completely different. The study also succeeds in modulating the luminescence species by counter cations in both solution and solid states. To the best of the current knowledge, this is the first report that anion‐based luminescent materials can show the different luminescent species not only in solution but also in the mechanochromic behaviors depending on the type of counter cations. This fundamental research on nCA demonstrates anion‐based emitters as a new platform for stimuli‐responsive materials.

Continuous production of gamma aminobutyric acid by engineered and immobilized Escherichia coli whole-cells in a small-scale reactor system

γ-Amino butyric acid (GABA) is a non-proteinogenic amino acid and a human neurotransmitter. Recently, increasing demand for food additives and biodegradable bioplastic monomers, such as nylon 4, has been reported. Consequently, considerable efforts have been made to produce GABA through fermentation and bioconversion. To realize bioconversion, wild-type or recombinant strains harboring glutamate decarboxylase were paired with the cheap starting material monosodium glutamate, resulting in less by-product formation and faster production compared to fermentation. To increase the reusability and stability of whole-cell production systems, this study used an immobilization and continuous production system with a small-scale continuous reactor for gram-scale production. The cation type, alginate concentration, barium concentration, and whole-cell concentration in the beads were optimized and this optimization resulted in more than 95 % conversion of 600 mM monosodium glutamate to GABA in 3 h and reuse of the immobilized cells 15 times, whereas free cells lost all activity after the ninth reaction. When a continuous production system was applied after optimizing the buffer concentration, substrate concentration, and flow rate, 165 g of GABA was produced after 96 h of continuous operation in a 14-mL scale reactor. Our work demonstrates the efficient and economical production of GABA by immobilization and continuous production in a small-scale reactor.

Geochemical evaluation of groundwater around Chromepet tannery belt, Southern India

The study appraises the geogenic and anthropogenic contamination of groundwater around tanneries located in Chromepet, Southern India. Thirty-six groundwater samples were examined for major anions, cations and trace metals concentration. The concentration of chromium (Cr), iron (Fe) and lead (Pb) in the study area ranges from 0.04 to 0.51 mg/L, 0.001–1.07 mg/L and 0.001–0.09 mg/L respectively. 97% of the samples exceeded the acceptable range for Cr whereas, lead and iron exceeded 89 and 8% of the samples respectively. The high concentrations of chromium, iron and lead in the groundwater are due to the influence of tannery effluents. The majority of the samples in the study area suggested silicate weathering. The piper plot reveals that 50% of the water samples have Na–Cl type water which is possibly due to anthropogenic sources. The Chadha plot revealed that silicate weathering and ion exchange govern the bulk of groundwater chemistry in freshwater aquifers owing to carbonate precipitation and mineral dissolution. Durov plot highlights that the bulk of the samples has no dominating anion or cation types, indicating simple dissolution or mixing. Saturation Index (SI) reveals that 50% of the samples were supersaturated due to calcite and dolomite precipitation. Principal Component Analysis (PCA) 1 suggested secondary salt discharge from geogenic and anthropogenic processes due to tanning industries. Increasing the performance of wastewater treatment plants is essential to improve the groundwater quality of the region under tannery influence.

Phase Behavior of Aqueous Mixtures of Sodium Alginate with Fish Gelatin: Effects of pH and Ionic Strength.

The phase behavior of aqueous mixtures of fish gelatin (FG) and sodium alginate (SA) and complex coacervation phenomena depending on pH, ionic strength, and cation type (Na+, Ca2+) were studied by turbidimetric acid titration, UV spectrophotometry, dynamic light scattering, transmission electron microscopy and scanning electron microscopy for different mass ratios of sodium alginate and gelatin (Z = 0.01-1.00). The boundary pH values determining the formation and dissociation of SA-FG complexes were measured, and we found that the formation of soluble SA-FG complexes occurs in the transition from neutral (pHc) to acidic (pHφ1) conditions. Insoluble complexes formed below pHφ1 separate into distinct phases, and the phenomenon of complex coacervation is thus observed. Formation of the highest number of insoluble SA-FG complexes, based on the value of the absorption maximum, is observed at рHopt and results from strong electrostatic interactions. Then, visible aggregation occurs, and dissociation of the complexes is observed when the next boundary, pHφ2, is reached. As Z increases in the range of SA-FG mass ratios from 0.01 to 1.00, the boundary values of рНc, рHφ1, рHopt, and рHφ2 become more acidic, shifting from 7.0 to 4.6, from 6.8 to 4.3, from 6.6 to 2.8, and from 6.0 to 2.7, respectively. An increase in ionic strength leads to suppression of the electrostatic interaction between the FG and SA molecules, and no complex coacervation is observed at NaCl and CaCl2 concentrations of 50 to 200 mM.

DOUBLE BUTTON FIXATION SYSTEM FOR THE TREATMENT OF ACUTE HIGH-GRADE ACROMIOCLAVICULAR JOINT DISLOCATION

Background: Acromioclavicular joint injuries represent the spectrum of soft tissue disruptions. These injuries usually occur in young males associated with athletic activities in which a direct blow to the lateral aspect of the shoulder occurs. Athletes belonging to the population at risk individuals, especially those who play football, rugby, or hockey. Conservative management is still considered a better modality for type 1, type 2, and some type 3 injuries. This prospective interven Materials and methods: tional study was conducted on patients who underwent surgery for AC joint dislocation. Mini-open surgery with a double-button xation technique was performed. Rockwood classication types 4-6 were included in the study. Proper pre-operative radiographs were obtained for better planning and management. Follow-up was taken at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months. A total of 24 patients were included in the Results: study, with a mean age of 32.54 years. Among them 19(79.16%) were male and 5(20.83%) were females. According to Rockwood classication, 18(75%) patients belonged to type 4 injuries and 6(25%) patients to type 5 injuries. The mean VAS score at the nal follow-up was 0.16±0.38 which was signicantly improved from the pre-operative value of 6.87±1.15. The improvement in DASH score was from 19.6±2.66 preoperatively to 0.35±1.42 at 12 months postoperatively. There were no complications associated with the procedure. Acute traumatic Conclusion: high-grade acromioclavicular joint dislocations should be treated with operative methods. Double button xation device using a mini-open technique provides adequate exposure, better anatomical xation, and excellent functional outcomes.

Role of Fe/Co Ratio in Dual Phase Ce0.8Gd0.2O2-δ-Fe3-xCoxO4 Composites for Oxygen Separation.

Dual-phase membranes are increasingly attracting attention as a solution for developing stable oxygen permeation membranes. Ce0.8Gd0.2O2-δ-Fe3-xCoxO4 (CGO-F(3-x)CxO) composites are one group of promising candidates. This study aims to understand the effect of the Fe/Co-ratio, i.e., x = 0, 1, 2, and 3 in Fe3-xCoxO4, on microstructure evolution and performance of the composite. The samples were prepared using the solid-state reactive sintering method (SSRS) to induce phase interactions, which determines the final composite microstructure. The Fe/Co ratio in the spinel structure was found to be a crucial factor in determining phase evolution, microstructure, and permeation of the material. Microstructure analysis showed that all iron-free composites had a dual-phase structure after sintering. In contrast, iron-containing composites formed additional phases with a spinel or garnet structure which likely contributed to electronic conductivity. The presence of both cations resulted in better performance than that of pure iron or cobalt oxides. This demonstrated that both types of cations were necessary to form a composite structure, which then allowed sufficient percolation of robust electronic and ionic conducting pathways. The maximum oxygen flux is jO2 = 0.16 and 0.11 mL/cm2·s at 1000 °C and 850 °C, respectively, of the 85CGO-FC2O composite, which is comparable oxygen permeation flux reported previously.