Ammonium Thiocyanate Solution Research Articles

Stress corrosion cracking mechanisms in bridge cable steels: Anodic dissolution or hydrogen embrittlement

Two key mechanisms, anodic dissolution, and hydrogen embrittlement, govern the stress corrosion cracking (SCC) in bridge cable steel wires. This study investigates the predominant mechanism influencing the SCC fracture time of bridge cable steel wires through electrochemical methods and thermal desorption analysis (TDA), offering protective measures. It contrasts the impacts of these mechanisms on electrochemical and mechanical properties and fracture morphology. The results show that the main mechanism of SCC in ammonium thiocyanate (NH4SCN) solution is hydrogen embrittlement (HE). Applying an anodic current (50 A/m2) can reduce the hydrogen absorption from 4.99 ppm to 0.2 ppm, and extend the fracture time from 26.1 h to 46.1 h. For the HE type SCC, the corrosion potential of the steel wire does not change with the corrosion time, and the tensile strength and diameter of the steel wire are the almost same as before corrosion. This research provides a theoretical basis for analyzing and protecting bridge cable steel wires against SCC.

Hydrogen Embrittlement Detection Technology Using Nondestructive Testing for Realizing a Hydrogen Society.

Crack detection in high-pressure hydrogen gas components, such as pipes, is crucial for ensuring the safety and reliability of hydrogen infrastructure. This study conducts the nondestructive testing of crack propagation in steel piping under cyclic compressive loads in the presence of hydrogen in the material. The specimens were hydrogen-precharged through immersion in a 20 mass% ammonium thiocyanate solution at 40 °C for 72 h. The crack growth rate in hydrogen-precharged specimens was approximately 10 times faster than that in uncharged specimens, with cracks propagating from the inner to outer surfaces of the pipe. The fracture surface morphology differed significantly, with flat surfaces in hydrogen-precharged materials and convex or concave surfaces in uncharged materials. Eddy current and hammering tests revealed differences in the presence of large cracks between the two materials. By contrast, hammering tests revealed differences in the presence of a half size crack between the two materials. These findings highlight the effect of hydrogen precharging on crack propagation in steel piping and underscore the importance of early detection methods.

Hydrogen-assisted cracking and damage tolerance of high-strength lath-martensite steel bars for structural applications

The paper addresses the hydrogen-assisted cracking and damage tolerance of high-strength lath martensite steel bars assessed from slow strain rate tensile tests. These were carried out on fatigue precracked specimens simultaneously charged with hydrogen in a standardized 20 % aqueous solution of ammonium thiocyanate at 50 °C and in air, at room temperature, for comparison. The fractographic analysis of the tested specimens showed the steel sensitivity to hydrogen uptake, which gives rise to the sub-critical extension of the pre-existing crack in two phases, initiation and growth, with both hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP) being synergically involved as damage mechanisms. Despite this, the damage tolerance behavior of the steel is highly satisfactory because the crack size causing the steel failure in tension slightly exceeds the theoretical limit of plastic collapse under combined tension and bending loading, regardless of the environment aggressiveness. Although H-assisted failure loads fit the theoretical limit loads, the fast propagation of the crack under constant load beyond the small-scale yielding regime could represent a real threat for the structural use of these steel bars in aggressive media unless the service loads are limited in accordance with such behavior.

A mononuclear N,N,N,O donor schiff base Cu(II) complex inhibits bacterial biofilm formation and promotes apoptosis and cell cycle arrest in prostate cancer cells

In this work, we report a distorted square pyramidal mononuclear copper(II) complex [Cu(L)(NCS)] (1) which was obtained by the reaction of the aqueous solution of ammonium thiocyanate to a methanolic solution of copper nitrate trihydrate and corresponding Schiff-base ligands. Schiff bases, HL (C12H19N3O) act as a tetradentate Schiff base, derived from 1:1 condensation of o-hydroxyacetophenone and diethylenetriamine. The synthesized complex has been successfully characterized based on elemental analysis and Infrared (IR) spectroscopy. The structure of complex 1 was confirmed by single-crystal X-ray diffraction study. In our study, we investigated synthesis, structural characterization, antimicrobial, anti-biofilm, and anti-cancer activity, and plausible mechanism of action of a novel mononuclear copper(II) schiff base complex. Increasing microbial resistance to several commercially available or traditional antimicrobial compounds has become a major global health concern at present time. The mononuclear copper(II) complex exhibited potential antibacterial activity against two strains of the gram-negative pathogen Pseudomonas aeruginosa. The copper compound dependent damage of bacterial cell membrane and inhibition of bacterial biofilm formation were also identified. Moreover, complex 1 inhibited prostate cancer cell growth, and migration by inducing apoptosis and arresting the cell cycle at the G2/M phase. Based on the results, we are suggesting our novel mononuclear copper(II) compound as a potential candidate for the development of new antibacterial and anti-cancer drugs.

A Refractive Index- and Density-Matched Liquid–Liquid System Developed Using a Novel Design of Experiments

Refractive index and density matching are essential for optical measurements of neutrally buoyant liquid–liquid flows. In this study, we proposed a design of experiments (DoE) to develop refractive index and density matching systems, including objective setting, candidates screening, sampling and fitting, and a detailed matching process. Candidates screening criteria based on the density and refractive index ranges of the aqueous and organic phases were used. Using the DoE, we proposed a system with a ternary aqueous phase potassium thiocyanate (KSCN)/ammonium thiocyanate (NH4SCN) solution and m-dichlorobenzene/tripropionin solution as the organic phase to achieve the tuning of the RI and density simultaneously. Empirical correlations of the refractive index and density with respect to the concentration and temperature for the three mixtures were obtained by combining Latin hypercube sampling with binary polynomial fitting. Correlations were validated with existing data in the literature and were found to align with deviations as low as 4×10−4 for the refractive index and 2×10−3 g⋅cm−3 for the density. Using the correlations, the refractive indices for the ternary aqueous phase, the binary organic phase, and the device materials were matched to be equal. Density matching was performed for the liquid–liquid phases as well. Refractive index- and density-matched recipes could be obtained for a wide range of temperatures (15–65 °C) and device materials (PMMA, borosilicate glass, quartz, and silica gel). These recipes provide options for the optical measurement of a liquid–liquid system required to neutralize buoyancy.

TRANSFER OF A DROP MATERIAL DURING THE PRIMARY CAVERN FORMATION

The transfer of a freely falling drop matter in the bulk of a target fluid at rest at the stage of primary cavity formation was traced by high-speed video recording for the first time. In the experiments, drops of water, ink solution (diluted in a ratio of 1:100) or a saturated solution of baking soda with a diameter of D = 0.43 cm fell with velocity of U = 3.1 m/s into fresh water or a 20% ammonium thiocyanate solution in the splash formation mode. In all experiments, the wall of the growing cavity was penetrated by thin fibers containing drop matter, which form an intermediate fine-structured layer. After the end of the fiber growth stage with a duration of 7–8 ms, the diffusion smoothed the concentration gradients, a liquid shell of intermediate density with a thickness of 1.5 to 0.7 mm was formed around the growing cavity. The shell is separated by a sharp boundary from the target fluid. A new group of inclined fibrous loops was formed in the wake of the collapsing cavity.

Synthesis, Biological Activity of Trimethoprim derivative and the Complexes

This study demonstrates the synthesis of new ligands derived from trimethoprim with their Iron(III) and copper (ll) complexes. At the beginning, preparing new ligands, the first namly N, N’-(5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diyl)bis(3,4,5-trihydroxy benza mide)and the Ligand second namly N, N’-(((5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diyl) bis(azanediyl))bis(carbonthioyl) bis(3,4,5-trihydroxybenzamide) which prepared by nucleophilic addition of trimethoprim to Gallic chloride and prepared also by nucleophilic addition of trimethoprim to the Solution of Ammonium thiocyanate and Gallic chloride. Ferric Ion (III) and Copperic Ion (ll) complexes have been prepared with molar ratio [1:2]. The synthesis ligands have been characterized by Uv-Visible, FT-IR, 1HNMR, 13CNMR and EI-mass, while the complexes have been characterized by elemental analysis, Uv-Visible, FT-IR, Conductivity measurements and thermogravemtric (TgA) analysis. The ligands acts as multiple sites coordinating with ferric ion and copper ion, Via lone pair of nitrogen atom of NHC= and phenolic oxygen. In Vitro, the ligands and complexes have been tested for their growth Inhibitory activity against Gram negative bacteria Salmonella Spp and Gram Positive Staphylococcus Spp. The results of the test indicate that the synthesized compounds possessed a high inhibition effectiveness comparative with trimethoprim.

Damage tolerance and failure analysis of tie-down cables after long service life in a cable-stayed bridge

The paper examines the damage tolerance of prestressing steel wire-strands failed after being exposed without protection to environmental action for 30 years as tie-down cables of a cable-stayed bridge. The influence of corrosion pitting, cross-section losses and possible assisted cracking on the tensile behavior of the Zn-coated prestressing steel strand-wires was experimentally determined, as well as their susceptibility to aggressive environments. A damage tolerance assessment was completed by performing fracture tests of as-received wire-samples exposed to an aqueous solution of ammonium thiocyanate while tensile loaded by applying a constant load followed by an increasing load at low strain rate. The fractographic analysis of the wires broken in-service and in-laboratory proved the induced damage to be very similar and provided evidence of environmental damage in some of the service ruptures. The damage tolerance assessment is in agreement with the two types of wire ruptures found in the failed wire-strands. These sequentially occurred over the 30 years of service, with the brittle ruptures of the mostly exposed peripheral wires being due to environmentally assisted cracking and preceding the ductile ones of the remaining wires by mechanical overloading.

Thiocyanate-Treated Perovskite-Nanocrystal-Based Light-Emitting Diodes with Insight in Efficiency Roll-Off.

Light emitting diodes (LED) based on halide perovskite nanocrystals (NC) have received widespread attention in recent years. In particular, LEDs based on CsPbBr3 NCs were the object of special interest. Here, we report for the first time green LED based on CsPbBr3 NCs treated with ammonium thiocyanate solution before purification with polar solvent. The champion device fabricated based on the treated CsPbBr3 NCs showed high efficiency and high stability during operation as well as during storage. A study on morphology and current distribution of NC films under applied voltages was carried out by conductive atomic force microscopy, giving a hint on efficiency roll-off. The current work provides a facile way to treat sensitive perovskite NCs and to fabricate perovskite NC-based LED with high stability. Moreover, the results shed new light on the relation between film morphology and device performance and on the possible mechanism of efficiency roll-off in NC LED.

Synthesis of Iron Nanoparticles by Thermal Decomposition of Diironnonacarbonyl in Ionic Liquid and Their Potential Use as Nanotracers for Mixer Studies in Liquids Feeds

Iron nanoparticles with dynamic light scattering median diameter around 10 nm have been prepared by thermal decomposition under a nitrogen atmosphere from diironnonacarbonyl (DINC) dissolved in n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF). The effect of temperature changes in the range of 170&#176C - 200&#176C and changes in concentration of DINC in BMIMBF in the range of 0.1% - 0.9% on the properties of obtained iron nanoparticles has been investigated. The stable dispersion of iron nanoparticle in ethanol has been prepared after separation of nanoparticles from ionic liquid by centrifugation following by their re-dispersion in ethanol. The possibility of quantitative analysis of iron content in ethanol dispersion by deposition of ferromagnetic nanoparticles on the surface of plastic-protected neodymium magnet, dissolution of iron in hydrochloric acid and addition of ammonium thiocyanate solution following by spectrophotometric determination of iron cations at wavelength of 490 nm has been investigated. The feasibility of using the same approach in case of addition of ethanol dispersion of iron nanoparticles to the liquid animal feeds for evaluation of efficiency of their mixing has been discussed.

Heat Capacity and Volume Properties of Ammonium Thiocyanate in N-Methylpyrrolidone Solution at 298.15 K

The heat capacity and volumetric properties of ammonium thiocyanate solutions in N-methylpyrrolidone are measured at 298.15 K by calorimetric and densimetric means. Concentration dependences of the partial and apparent molar heat capacities and volumes of the investigated systems are discussed. The standard partial molar heat capacity and volume of NH4CNS, and the standard heat capacity and volume of ammonium and thiocyanate ions in N-methylpyrrolidone at 298.15 K are calculated.

Layer-by-layer MoS2:GO composite thin films for optoelectronics device applications

With reference of our previous report (Appl. Surf. Sci. 474(2019)227), the molybdenum disulphide (MoS2) thin film were prepared by the dip-coating technique at different temperatures (400 °C–450 °C) using methanolic solution of ammonium molybdate and ammonium thiocyanate that are used as bare-substrate for the deposition of graphene oxide (GO) thin films. For the deposition of graphene oxide (GO), commercially purchased GO (0.5 mg in 10 mL aqueous solution) was deposited by dip-coating technique on dip-deposited MoS2 thin film to make layer-by-layer MoS2:GO composite thin films and hence studied their electronic and electrical behaviours. The micro-structural and surface morphology were studied using Raman spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy, whereas optical band estimated from the optical absorption spectra. The electronic structure and their bonding properties were studied using X-ray photoelectron spectroscopy and the electrical behaviours were observed from the current-voltage (I-V) characteristic curve. The formation of different phases of MoS:GO thin films show an enhanced electronic and electrical performance due to their unique-structure and the synergetic effect of MoS2:GO nanosheets when compared to those of bare MoS2.

ASPECTS OF MEDICINES QUALITY EVALUATION BY ELECTRICAL SENSING ZONE METHOD

The article describes standard methodological approaches to the determination of subvisible particles by electrical sensing zone method (the Coulter principle). The standard procedure of lyophilisate and powder preparation includes their dilution with Isoton® II Diluent (Beckman Coulter, USA) — 0.9 % sodium chloride solution containing a preservative agent (hereinafter — Isoton) under conditions free from particulate matter. The article provides a brief description of the Coulter principle which was included into the General monograph «Subvisible particulate matter in parenteral preparations» of the State Pharmacopoeia of the Russian Federation, 13th edition. It was demonstrated that most solutions for injection and infusion do not need special preparation before testing, whereas 13 % of such preparations need the addition of the diluent Isoton to increase their electrical conductivity for determination of subvisible particulate matter. The article presents the results of experimental studies that were aimed at modification of the standard sample preparation procedure for different medicinal products for the purpose of their evaluation in terms of subvisible particulate matter. A number of lyophilisates, powders, suspensions, and oily solutions can not be diluted with Isoton because of precipitate formation, so recommendations are offered for these types of products regarding the choice of alternative diluents (water, 4 % sodium chloride solution, ammonium thiocyanate solution in isopropanol, acetone, etc.) for obtaining electrically conductive solutions. Alternatively, it may be recommended to change the dilution mode (increase the time of dilution and/or diluent volume). Thus, the article provides rationale for using the Coulter principle for determination of subvisible particulate matter in various pharmaceutical forms.

Trigonal (1T) and hexagonal (2H) mixed phases MoS2 thin films

Molybdenum di-sulfide thin films of thickness <1500 Å, were prepared by the dip-coating technique at different baking temperatures within the range 400 °C–450 °C using methanolic solution of ammonium molybdate and ammonium thiocyanate and hence studied their different properties using X-ray diffraction (XRD), UV-vis spectroscopy, Photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and Current-Voltage (I-V) relationship measurements. XRD result shows that the MoS2 films are mixed metallic octahedral prismatic 1T- and trigonal prismatic bulk crystal 2H-phases. The I-V relationships show higher electrical conductivity for the films prepared at 400 °C and 450 °C than the films prepared at 425 °C. XPS measurement also shows the formation of mixed phases of MoS2 thin films as revealed by XRD. We have estimated the valence band maximum (VBM) and work functions from higher and lower energy range of UPS (He-I) spectra of MoS2 thin films prepared at 425 °C and 450 °C. The VBM are ∼4.4 eV & ∼4.2 eV and their work functions are ∼3.5 eV & ∼3.3 eV respectively that are correlated with conductivity and formation of mixed phases of MoS2 thin films.

Extraction of precious metals from industrial solutions by the pine (Pinus sylvestris) sawdust-based biosorbent modified with thiourea groups

A novel biosorbent based on pine (Pinus sylvestris) sawdust with chemical grafted thiourea groups was proposed for preconcentration of precious metals. A simple procedure was proposed for the synthesis of biosorbent by treating of sawdust with ammonium thiocyanate solution and a subsequent heat treatment at 160 °C. The biosorbent has been studied by thermogravimetry/differential scanning calorimetry (TGA/DSC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The adsorption properties for precious metals ions (Au3+, Pd2+, Pt2+, Pt4+, Ir4+, Rh3+, Ru4+) extraction have been studied. Biosorbent quantitatively extracted precious metals from dilute solutions of hydrochloric acid (0.5–4.0 M). Iron and non-ferrous metals were not extracted in these conditions. The adsorbent showed high adsorption capacity for precious metals: 0.4 (Au3+), 1.7 (Pd2+), 1.0 (Pt2+), 0.8 (Pt4+), 0.45 (Ru4+), 0.55 (Rh3+), 0.4 (Ir4+) mmol/g.Biosorbent was used for extraction and preconcentration of precious metals from industrial solutions of refinery. Enriched for precious metals desorbing solution was obtained as a result. It is possible to obtain precious metals powder by combustion of biosorbent after adsorption of precious metals.

Quantitative determination method and application of pharmaceutical adjuvant tween 80

Based on the fact that chromogenic reaction of blue complex, a reaction product which can be dissolved in organic solvents, can be realized by polyethoxy and ammonium thiocyanate in tween 80, a rapid and accurate way for the determination for tween 80 in pharmaceutical adjuvant was established in this study, providing reliable technical means for quality control of traditional Chinese medicine injections. Based on the study of reaction kinetics, chromogenic reaction temperature and time, as well as extraction of organic solvents and other key conditions were optimized, and Kumu injection was used as the test material for method validation and applicability investigation. It was finally determined that 3 mL ammonium thiocyanate solution was added in the sample solution, and the reaction was carried out in a boiling water bath for 2 h. After cooling to room temperature, 5 mL of dichloromethane was added to extract the chromogenic product. The absorbance value was measured at the wavelength of 623 nm to calculate the tween 80 content in the sample. Under optimized conditions, tween 80 solution showed a good linear relationship with the absorbance in the range from 0.8 mg to 3.0 mg. The linear regression equation was y＝0.258x-0.047. The correlation coefficient r was 0.999 6. Under the experimental conditions, the average recovery was 99.66%, and the precision RSD was less than 2.0%. The results showed that this method can quickly and accurately determine the content of tween 80 in Kumu injection, and it could be applicable to the quality control of traditional Chinese medicine injections.

Environment-assisted failure of structural tendons for construction and building applications

The work focuses on the environment-assisted crack growth conditions and addresses the threshold stress intensity factors of three commercial high-strength steel bars widely used in construction and building tensile applications. To quantify the sensibility to stress corrosion cracking, chevron-notched short bar specimens were simultaneously subjected to tension tests and hydrogen embrittlement in both artificial seawater and ammonium thiocyanate solution. The latter was used to enhance the stress corrosion damage and to reveal the fracture morphologies that characterize the rupture of the bars. Thus, new insights regarding the lifetime of the bars in seawater environment are brought into attention.

Environmental effects on large diameter high-strength rods for structural applications

Abstract This work aims assessing the stress corrosion cracking behaviour in distinct aggressive environments of a commercial class of high-strength low alloy steel bars of randomly oriented pearlite structure, intensively used in tensioning systems of structural engineering. The research is based on tensile testing of un-notched and circumferentially notched cylindrical specimens that are simultaneously subjected to slow strain rate loading and environmental damage. To vary the damage intensity, seawater media of distinct aggressiveness, and ammonium thiocyanate solution are employed. In addition, fracture tests of chevron-notched short bar specimens, fatigue pre-cracked perpendicularly to the bars axis, provided the experimental data to benchmark the bars toughness. The results indicate that damage inducing failure consists of pearlite interlamellar decohesion as result of hydrogen-induced local embrittlement of the steel. This activates a continuous stable cracking of sickle shape until brittle rupture of the remnant undamaged ligament is finally triggered.

Separation and recovery of Pd(II) and Pt(II) from cyanide liquors of Pd-Pt flotation concentrate via solvent extraction

BACKGROUND Thus far, separation and recovery of Pd(CN)42- and Pt(CN)42- from cyanide liquors have not been reported. In this study, the process of co-extracting and separating Pd(II) and Pt(II) over Fe(III), Cu(I), Co(III), and Ni(I) from alkaline cyanide liquors was investigated. RESULTS The results showed that almost all Pd(II) and Pt(II) (>98.0%) could be simultaneously extracted by phenoxyethyl dimethyl palmitylammonium bromide (PDPB), whereas Fe(III), Cu(I), Co(III), and Ni(I) was below 3.0% under optimum conditions. Furthermore, Pd(CN)42- and Pt(CN)42- were separated and recovered by the two-step stripping process. First, Pd(CN)42- in mixed organic phase was stripped by a 2.0 mol L−1 ammonium thiocyanate solution. The stripping percentage of Pd(CN)42- was >98%, whereas the stripped Pt(CN)42- was below 1%. Second, more than 97.5% Pt(CN)42- in the loaded organic phase could be stripped using 1.0 mol L−1 thiodiglycol solution. Recovery ratios for both Pd(II) and Pt(II) were above 95%. The organic phase could be reused for at least 6 cycles of extraction–stripping processes. The mechanisms of extraction reaction were deduced to be ion-association mechanisms. CONCLUSION The process could be applied for extracting and separating palladium and platinum from the cyanide leaching liquor of the flotation concentrate. © 2016 Society of Chemical Industry

Hydrogen Induced Damage in Heavily Cold-Drawn Wires of Lean Duplex Stainless Steel

The paper addresses the sensitivity to hydrogen embrittlement of heavily cold-drawn wires made of the new generation of lower alloyed duplex stainless steels, often referred to as lean duplex grades. It includes comparisons with similar data corresponding to cold-drawn eutectoid and duplex stainless steels. For this purpose, fracture tests under constant load were carried out with wires in the as-received condition and fatigue-precracked, in air and exposed to ammonium thiocyanate solution. Microstructure and fractographic observations were essential means for the cracking analysis. The effect of hydrogen-assisted embrittlement on the damage tolerance of lean duplex steels was assessed regarding two macro-mechanical damage models that provide the upper bounds of damage tolerance and accurately approximate the failure behavior of the eutectoid and duplex stainless steels wires.