Neutral Salt Solutions Research Articles

In-situ monitoring of changes in temperature and microstrain during the chemical corrosion of stone cultural relics

Temperature changes during the chemical corrosion of stone cultural relics affect the condensation and evaporation of water and chemical reactions between soluble substances and corrosive solutions. This ultimately leads to changes in the internal structure and composition of the artifacts, which in turn lead to changes in the microstrain of cultural relics. To obtain in-situ real-time information on changes in the temperature and microstrain of stone cultural relics during chemical corrosion damage, a fiber Bragg grating (FBG) detection system was developed. The detection principle for the temperature and microstrain of sandstone was provided. Thermal field emission scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry were used to characterize the surface morphology, composition, and pore structure of the sandstone samples, respectively. The temperature and microstrain changes of the sandstone samples under deionized water with different acidic/alkaline and salt solutions and at different temperatures were examined online in situ using the FBG measurement system. The results indicate that the dissolution of sandstone in the acidic solution (H2SO4 and NaHSO4) resulted in an exothermic chemical reaction as well as the dissolution of sandstone in the neutral salt solution (Na2SO4) and alkaline solution (NaOH and Na2CO3) led to material conversion and exothermic chemical reaction; the deionization reaction belongs to the dissolution reaction. The NaHSO4 solution caused the most serious corrosive disease on the sandstone surface. When the temperature of the NaHSO4 solution was 60 °C, the temperature and microstrain of the sandstone reached 63.9 °C and 253.6 με, respectively. The results of this study can support the research of revealing the corrosion mechanism of sandstone in different environments.

Precision Electrochemical Micro-Machining of Molybdenum in Neutral Salt Solution Based on Electrochemical Analysis

Molybdenum is an important material in modern industry, widely used in extreme environments such as rocket engine nozzles and microelectrodes due to its high melting point, excellent mechanical properties, and thermal conductivity. However, as a difficult-to-machine metal, traditional machining methods struggle to achieve the desired microstructures in molybdenum. Electrochemical machining (ECM) offers unique advantages in manufacturing fine structures from hard-to-machine metals. Studies have shown that molybdenum exhibits a fast corrosion rate in alkaline or acidic solutions, posing significant environmental pressure. Therefore, this study investigates the electrochemical machining of molybdenum in neutral salt solutions to achieve high-precision microstructure fabrication. First, the polarization curves and electrochemical impedance spectroscopy (EIS) of molybdenum in NaNO3 solutions of varying concentrations were measured to determine its electrochemical reaction characteristics. The results demonstrate that molybdenum exhibits good electrochemical reactivity in NaNO3 solutions, leading to favorable surface erosion morphology. Subsequently, a mask electrochemical machining technique was employed to fabricate arrayed microstructures on the molybdenum surface. To minimize interference between factors, an orthogonal experiment was used to optimize the parameter combination, determining the optimal machining process parameters. Under these optimal conditions, an array of micro-groove structures was successfully fabricated with an average groove width of 110 μm, a depth-to-width ratio of 0.21, an aspect ratio of 9000, and a groove width error of less than 5 μm.

The effect of ions on liquid-solid interface investigated by charge sensitive direct current droplet-based electricity generator

The contact electrification (CE) between DI water and SiO2 or fluorinated polymer has been proven to be mainly due to electron transfer, which is significantly influenced by ions in solution. However, how these ions in water affect the charge transfer at the liquid-solid (L-S) interface is still unresolved, especially for the already charged friction layer. Here, a direct current droplet-based electricity generator (DC-DEG) which is sensitive to the change of charge transfer at the L-S interface is adopted to detect the effects of ions in the neutral salt solution on the charged PTFE surface. The distribution of ions on the charged L-S interface (the change of electric potential on the solid surface) and its effects on the output of DC-DEGs have been studied. The results indicate that the charge transfer of droplets and then the output of DC-DEGs are closely related to the concentrations of salt solutions. Anions can enhance the surface potential of PTFE due to their adsorptions on PFTE while cations can reduce it due to their screen effect. At low ionic concentrations, the surface potential enhancement caused by anion adsorption is larger than that surface potential reduction caused by screen effect from cations. At high ionic concentrations, the electrostatic screen effect of cations increases a lot to weaken the surface potential and reducing the charge separation of droplets induced by electrostatic induction (EI). This work explains the redistribution process of ions at the L-S interface and also provides a clever solution for improving the electrical output performance of DEGs.

Specific energy consumption of electro-contact-chemical treatment of metals with a vibrating tool in the electrolyte

According to the specific energy consumption, the shaping processes are arranged in three energy levels. Electrophysical and electrochemical methods of metal processing are at the third level, where the specific energy consumption is more than 6∙104 J/cm3. The analysis of the literature data showed the inconsistency of the specific costs of some authors. The specific energy consumption of electrical contact processing cannot be commensurate with the costs of electrochemical processing due to the different sizes of the particles removed from the surface of the workpiece. There are no literature data on the specific energy consumption of electro-contact-chemical treatment of metals with a vibrating instrument in the electrolyte, therefore, experiments have been carried out with the fixation of current, voltage and interelectrode gap oscillograms. The method of calculation of specific energy consumption according to the oscillograms of the process is given. The energy costs for vibration of the electrode-tool are calculated, which are an order of magnitude less for electro-contact-chemical treatment. When the vibration amplitude decreases or the voltage on the electrodes increases, the process in the interelectrode gap turns into dimensional arc processing. When electro-contact-chemical treatment of metals with a vibrating tool in water, the specific energy consumption is equal to (3.5–3.8) · 105 J/cm3, which corresponds to electrocon-tact treatment. It is assumed that the use of aqueous solutions of neutral salts will lead to a reduction in energy costs.

Effect of rare earth La2O3 on the microstructure and corrosion resistance of CoCrFeNiMoSi high entropy alloys

This study systematically investigated the effect of incorporating trace amounts of La2O3 into the CoCrFeNiMoSi high-entropy alloy (HEA) system on its corrosion resistance in neutral chloride ionic salt solutions. The CoCrFeNiMoSi HEA coatings and CoCrFeNiMoSi-0.5 % La2O3 HEA coatings were prepared using the laser melting technique. The microstructure, phase composition, and electrochemical corrosion performance were characterized using X-ray diffraction, scanning electron microscopy, electrochemical workstation, and X-ray photoelectron spectroscopy. The experimental results revealed that the microstructure primarily comprised face-centered cubic structure (FCC), body-centered cubic structure (BCC), and Si-rich intermetallic compounds. Notably, the addition of La2O3 facilitated the formation of the FCC phase. Electrochemical tests demonstrated that the CoCrFeNiMoSi-0.5 % La2O3 HEA coating exhibited an elevated corrosion potential and a reduced self-corrosion current density when compared to the CoCrFeNiMoSi HEA coating. The X-ray photoelectron spectroscopy (XPS) data revealed a notable increase in the Cr content and oxide content of the passive film when La2O3 was present in the HEA. This resulted in the formation of a more protective passivated film. Consequently, the potential utilization of rare earth lanthanum oxide to enhance the corrosion resistance of HEA coatings is promising.

Facile preparation of polymer-based heat dissipation composite coating with enhanced thermal conductivity via optimizing synergistic effect of multi-scale fillers

Aluminum radiator plays a significant role in thermal managing system of passive heat dissipation for high power consuming microelectronic devices. Although inspiring strategies have been proposed to design and prepare polymer-based composites with high thermal conductivity in previous reports, it remains urgent to develop practical techniques for economically fabricating thermally conductive composite coatings in large-scale. To construct efficient heat dissipation film, two-dimensional (2D) graphene nanoplatelets (GNPs)/hexagonal boron nitride nanoplatelets (BNNPs) hybrid fillers are dispersed in polydimethylsiloxane (PDMS) solution with branch-like porous magnéli-phase Ti4O7 microparticles as heat conducting paths, and fabricated via convenient spray-coating. Thermal conductivity of the cured coating presents two-fold increase to 5.339 W m−1 K−1 as compared to the coating without Ti4O7, and a heat dissipation ratio of 13.96 %. Furthermore, the composite coating demonstrates excellent corrosion resistance under neutral salt solution spray. The as-prepared composite coating is of great potential to be applied as protective coating for aluminum radiators.

Enhancing Surface Integrity of Micro-Holes Machined on Inconel 718 using Shaped Tube Electrochemical Machining via Hydroxide Mixing

This research explores enhancing surface integrity of high aspect ratio (AR>5) micro-holes machined on Inconel 718 using Shaped Tube Electrochemical Machining (STEM) by mixing limited amount of metal hydroxides in the different electrolyte solutions. Typically, STEM employs hazardous acid solutions. These solutions cause machine corrosion, environmental risks, and harm to operators. This research aims to explore eco-friendly and safe alternatives. The efficacy of adding NaOH or KOH to eco-friendly neutral aqueous solutions of NaCl, KBr, and NaNO3 on machined surfaces is expounded. We assess electrolyte mixing parameters, including concentration and composition, and explore the effects of varying electrolyte temperature, voltage, and tool feed rate. Surface assessment uses SEM, EDX, XRD, and profilometry. Results reveal that adding hydroxides to neutral salt solutions improves surface roughness and reduces pitting. Hydroxide ions aid in dissolving oxide films during STEM of Inconel 718. Under specific conditions (9 g l−1, 18°C, 8 V, 0.8 mm min−1), NO3│OH yielded the lowest Ra (1.64 μm), while Br│OH resulted in the highest Ra (2.14 μm) with pitting, cracks, and deposits. NO3│OH exhibited a 25% decrease in Ra when a hydroxide concentration rise from 3 g l−1 to 15 g l−1. This research supports eco-friendly STEM for improved surface quality without process performance compromise.

Rapid Elution of 226Th from a Two-Column 230U/226Th Generator with Diluted and Buffer Solutions.

A radionuclide generator of the short-lived alpha emitter 226Th was proposed. An original scheme consisting of two in-series chromatographic columns was developed for rapidly producing a neutral citric-buffered eluate of high purity 226Th. The first column filled with TEVA resin retained the parent 230U, while 226Th was eluted with 7 M HCl solution to be immediately adsorbed on the second column containing DGA resin or UTEVA resin. Having substituted the strongly acidic medium of second column with neutral salt solution, 226Th was desorbed with diluted citric buffer solution. One cycle of generator milking took 5-7 min and produced >90% of 226Th in 1.5 mL of eluate (pH 4.5-5.0) appropriate for direct use in radiopharmaceutical synthesis. The 230U impurity in 226Th eluate was less than 0.01%. The proposed two-column 230U/226Th generator was tested over 2 months including a second loading of 230U additionally accumulated from 230Pa.

Microencapsulation of Capsaicin in Chitosan Microcapsules: Characterization, Release Behavior, and Pesticidal Properties against Tribolium castaneum (Herbst).

Capsaicin is a capsaicinoid in hot chili peppers, with excellent antibacterial and antimicrobial activities and a good safety profile, but its poor solubility and instability restrict its effectiveness. This limitation may be mitigated by encapsulation. Herein, capsaicin microcapsules (CCMs) were prepared through layer-by-layer self-assembly, using chitosan and carboxymethyl chitosan as shell materials. The chemical and microstructure structural characterization was evaluated by the methods of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The SEM indicated the microcapsules were irregular in shape with an average size of about 100 μm. The encapsulation had a high loading efficiency of 64.31%. FTIR and XRD revealed the absence of the interaction between the core and shell materials and the amorphous nature of the CCMs. The analysis results of the microcapsules' release behavior showed the burst release of capsaicin in 7 days and a slow progression afterward in three solutions, with the highest release properties in a basic solution, followed by acidic and neutral salt solutions. The entomotoxicity of CCMs was conducted against Tribolium castaneum (Herbst), and its efficacy was compared with pure capsaicin. The CCMs were found to be highly effective against this pest. The LC50 value for capsaicin and its microcapsules was 31.37 and 29.75 mg/kg on adults, respectively. According to these values, T. castaneum's development and reproduction were significantly inhibited compared with the control group. The excellent physicochemical characteristics and insecticidal performance show a high application value for integrated pest control.

Electrochemical Polishing of Ti6Al4V Alloy Assisted by High-Speed Flow of Micro-Abrasive Particles in NaNO3 Electrolyte.

Electrochemical polishing (ECP) is an efficient and low-cost technology for polishing difficult-to-machine materials with complex structures. However, when an environmentally friendly neutral salt solution is used as the polishing electrolyte, a dense passivation film forms on the surface of passive metals, such as titanium alloy, with a serious detrimental effect on the polishing efficiency and surface quality. In this paper, we introduce an ECP method assisted by a high-speed flow of micro-abrasive particles (ECFAP). The contribution of the flowing micro-abrasive particles in the ECP process enables the electrochemical dissolution and abrasive polishing to occur simultaneously on the workpiece surface. The high-speed abrasive particles remove the passivation film formed under ECP, thereby improving the polishing efficiency and quality. We carried out the comparative tests of conventional ECP and the proposed ECFAP on a Ti6Al4V alloy in 10% NaNO3 electrolyte; the results show that, while the matrix material forms a soft high-impedance passivation film under ECP, this film is removed by the high-speed flowing abrasive particles under ECFAP. The proposed ECFAP method improves both the polishing efficiency and the surface quality. Finally, ECFAP-treated specimens with an optimum voltage of 3 V for 10 min exhibited an average surface roughness of 0.0953 µm.

Operando Monitoring of Local pH Value Changes at the Carbon Electrode Surface in Neutral Sulfate-Based Aqueous Electrochemical Capacitors.

The operando monitoring of pH during the charging and discharging of an electrochemical capacitor in an aqueous neutral salt solution is presented. Proper knowledge of transient and limiting pH values allows for a better understanding of the phenomena that take place during capacitor operation. It also enables the proper assignment of the reaction potentials responsible for water decomposition. It is shown that the pH inside the capacitor is strongly potential-dependent and different for individual electrodes; therefore, the values of the evolution potentials of hydrogen and oxygen cannot be precisely calculated based only on the initial pH of the electrolyte. The operando measurements indicate that the pH at the positive electrode reaches 4, while at the negative electrode, it is 8.5, which in theory could shift the theoretical operating voltage well beyond 1.23 V. On the other hand, high voltage cannot be easily maintained since the electrolyte of both electrode vicinities is subjected to mixing. Operando gas monitoring measurements show that the evolution of electrolysis byproducts occurs even below the theoretical decomposition voltage. These reactions are important in maintaining a voltage-advantaged pH difference within the cell. At the same time, the electrochemical quartz crystal microbalance (EQCM) measurements indicated that the ions governing the pH (OH–) that initially accumulated in the vicinity of the positive electrode enter the carbon porosity, losing their pH-governing abilities. pH fluctuations in the cell are important and play a vital role in the description of its performance during the cyclability at a given voltage. This is especially noticeable in cell floating at 1.3 V, where the pH difference between electrodes is the highest (6 units). The increase of the electrode separation distance acts similarly to the introduction of a semipermeable membrane toward the increase of the capacitor cycle life. During floating at 1.6 V, where the pH difference is not as high anymore (4 units), the influence of separation in terms of electrode stability, although present, is less notable.

A Review on Precision Polishing Technology of Single-Crystal SiC

Single-crystal SiC is a typical third-generation semiconductor power-device material because of its excellent electronic and thermal properties. An ultrasmooth surface with atomic surface roughness that is scratch free and subsurface damage (SSD) free is indispensable before its application. As the last process to reduce the surface roughness and remove surface defects, precision polishing of single-crystal SiC is essential. In this paper, precision polishing technologies for 4H-SiC and 6H-SiC, which are the most commonly used polytypes of single-crystal SiC, such as chemical mechanical polishing (CMP), photocatalytic chemical mechanical polishing (PCMP), plasma-assisted polishing (PAP), electrochemical mechanical polishing (ECMP), and catalyst-referred etching (CARE), were reviewed and compared with emphasis on the experimental setup, polishing mechanism, material removal rate (MRR), and surface roughness. An atomically smooth surface without SSD can be obtained by CMP, PCMP, PAP, and CARE for single-crystal SiC. However, their MRRs are meager, and the waste treatment after CMP is difficult and expensive. Moreover, PAP’s operation is poor due to the complex polishing system, plasma generation, and irradiation devices. A high MRR can be achieved by ECMP. In addition, it is an environmentally friendly precision polishing process for single-crystal SiC since the neutral salt solution is generally used as the electrolyte in ECMP. However, the formation of the egglike protrusions at the oxide/SiC interface during anodic oxidation would lead to a bigger surface roughness after ECMP than that after PAP is processed. The HF solution used in CARE was toxic, and Pt was particularly expensive. Ultrasonic vibration-assisted single-crystal SiC polishing and electrolyte plasma polishing (EPP) were discussed; furthermore, the research direction of further improving the surface quality and MRR of single-crystal SiC was prospected.

Effect of pyrolysis temperature on Si release of alkali-enhanced Si-rich biochar and plant response

Recent studies have shown that silicon (Si) dissolution from biochar may be influenced by the pyrolysis temperature. In addition, the enhancement of biochar by treatment with alkali has been proposed to produce a Si source that can be used for environmentally friendly plant disease control. In this study, biochars from rice straw and rice husk pretreated with KOH, CaO and K2CO3 and then pyrolyzed at 350, 450 and 550 °C were prepared to evaluate the effects of pyrolysis temperature on Si release and plant uptake from alkali-enhanced Si-rich biochar. Extractable Si and dissolution Si from the prepared biochars were assessed by different short-term chemical methods and long-term (30-day) release in dilute acid and neutral salt solutions, respectively, along with a rice potting experiment in greenhouse. For both rice straw- and husk-derived alkali-enhanced biochars (RS-10KB and HS-10K2B, respectively), increasing the pyrolysis temperature from 350 to 550 °C generally had the highest extractable Si and increased Si content extracted by 5-day sodium carbonate and ammonium nitrate (5dSCAN) designated for fertilizer Si by 61–142%, whereas non-enhanced biochars had more extractable Si at 350 °C. The alkali-enhanced biochars produced at 550 °C pyrolysis temperature also released 82–172% and 27–79% more Si than that of 350 °C produced biochar in unbuffered weak acid and neutral salt solutions, respectively, over 30 days. In addition, alkali-enhanced biochars, especially that derived from rice husk at 550 °C facilitated 6–21% greater Si uptake by rice and 44–101% higher rice grain yields than lower temperature biochars, non-enhanced biochars, or conventional Si fertilizers (wollastonite and silicate calcium slag). Overall, this study demonstrated that 550 °C is more efficient than lower pyrolysis temperature for preparing alkali-enhanced biochar to improve Si release for plant growth.

ИССЛЕДОВАНИЕ КИНЕТИЧЕСКИХ ЗАКОНОМЕРНОСТЕЙ ОКИСЛЕНИЯ МЕДИ ЭЛЕКТРОЛИЗОМ В НЕСТАЦИОНАРНЫХ УСЛОВИЯХ

Data on the study of the kinetics and mechanism of copper electro-oxidation -reduction processes in alkaline and neutral solutions were obtained in this work. Patterns of the electrochemical oxidation of copper using alternating current were established. Based on the data of polarisation measurements kinetic parameters were calculated: the heterogeneous rate constant, the effective activation energy of copper electro-oxidation, which allow to establish the course of the metal oxidation process in alkaline and neutral environments and its characteristics. Potentiodynamic measurements in alkaline solutions at a copper anode indicate the formation of Cu2O, CuO и Cu(OH)2. Anodic dissolution of copper in neutral salt solutions includes two main stages: the formation of Cu(I) and Cu(II) ions. It was found that the product of oxidation at high potentials is the Cu(II) ion. The nature of the anion electrolyte affects the rate of copper anodic oxidation, while the process occurs more efficiently in solutions of sulfate and sodium chloride and is accompanied by significant polarisation. Based on the study of kinetics the possibility of obtaining powders of metal oxide was shown, which further allowed to determine the parameters of the electrolysis process in non-stationary conditions in order to obtain highly dispersed materials based on copper oxides with specific physico-chemical properties.

(Invited) Understanding Multi-Component Transport and Reaction Phenomena in Bipolar Membranes Used for Electrosynthesis

Bipolar membranes (BPMs), which have long seen usage in electrodialysis reactors for the generation of acid and base, have recently demonstrated potential to become critical components in electrochemical synthesis devices. Because they can operate under large pH gradients, BPMs enable favorable environments for electrocatalysis at the individual electrodes. Critical to the implementation of BPMs in these devices is understanding the kinetics of water dissociation that occurs within the BPM junction as well as the co- and counter-ion crossover through the BPM, which both present significant obstacles to developing efficient and stable BPM-devices for electrosynthesis applications. Prior work has modeled ion transport in bipolar membranes in neutral salt solutions for electrodialysis. However, no model exists for the BPM under the harsh applied pH gradients that would be present in electrosynthesis, and there is significant need to explore the effects of the internal hydration on the lifetime and performance of BPMs in such environments. Additionally, a mechanistic understanding of water dissociation catalysis will be required to develop interfacial catalysts that enable the high current density operation required for scalable electrosynthesis of fuels.In this talk, we discuss modeling methodologies and physics inherent in BPMs and present our recent model of ion transport and water dissociation catalysis in BPMs across the pH scale. Specifically, we simulate multi-ion transport for a BPM with various electrolyte combinations on each side of the membrane, demonstrating the significance of co- and counter-ion crossover in BPMs operating under harsh pH gradients. We then investigate effects caused by hydration gradients that occur due to internal ion-exchange and examine potential methods for improving performance and mitigating crossover. Finally, we examine the impact of the interfacial water dissociation catalyst and perform sensitivity analysis on the key properties (catalyst point of zero charge and pKa) that dictate catalyst performance. These results provide information that is critical to developing a comprehensive understanding of multi-component phenomena in BPMs and to informing the design and implementation of BPMs in next-generation devices for the numerous electrosynthesis chemistries that benefit from operation under an applied pH gradient.

Controlling organic interference in determination of soil mineral nitrogen

AbstractInorganic nitrogen (N) in the form of exchangeable ammonium (NH4+), nitrate (NO3−), or nitrite (NO2−) is normally extracted by shaking soil with a neutral salt solution and is subject to interference by soluble organic N (SON). After optimizing sequential diffusion methods to expedite recovery of NH4+–N and (NO3− + NO2−)‐N, 15N‐tracer studies were conducted to ascertain whether extraction is quantitative when performed on soils amended with 2 g 15N kg−1 using 0.2, 1, and 2 M potassium chloride (KCl) and can be carried out by a simple leaching method instead of conventional shaking‐filtration. The results verified a significant decrease in SON interference with the optimized diffusion procedures and showed that (a) interference is more serious for NH4+–N than for (NO3− + NO2−)‐N, (b) 2 M KCl is required for quantitative recovery of 15NH4+–N, and (c) leaching virtually eliminates organic interference during diffusion of (NO3− + NO2−)‐N. The leaching‐diffusion approach minimizes the inflating effect of SON on soil inorganic N analyses and will be especially useful in N isotope studies.

Effect of Nano-Silica Volume Reinforcement on the Microstructure, Mechanical, Phase Distribution and Electrochemical Behavior of Pre-Alloyed Titanium-Nickel (Ti-Ni) Powder

Titanium-Nickel pre-alloyed powder was reinforced with Nano-Silica in 2%, 4% , 6% and 8 wt. % due to effectiveness of Nanoscale ceramic Reinforcement in improving the properties of Metals and Alloys. The compositions of the Pre-Alloyed powders and Nano Silica Approximately 50 nm in diameter and spherical in shape were weighed and mixed in Planetary Ball Mill followed by compaction at 50 MPa using a Uniaxial Compaction machine The green pellets obtained were sintered in Argon Environment for 5 hrs and allowed to furnace cool. The pellets were then sectioned through their cross-section for slices 3 mm thick followed by Cold-mounting and Soldering followed by cold mounting additionally. The Samples were analyzed via X-Ray Diffraction (XRD) for phase distribution as a function of variation in nano-Silica reinforcements and Microstructural analysis was performed via Optical Microscope. The effect of Volume percentage on the densification was determined via Archimedes principle and Micro-Vickers hardness was used for mechanical Evaluation. The Electrochemical Properties were evaluated using Potentio-Dynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in neutral salt solution (3.5% NaCl). The results indicated increasing dissolution of the TiNi phase into intermetallic Titanium-rich and Ni-rich phases in the matrix and hardening due to the Nano-Silica effect of Grain Boundary impingement and phase dissolution of Equiatomic phase and mixed behavior in Corrosion properties as determined by the electrochemical techniques whereas densification decreased due to poor plasticity of Nano-Silica and hinderance in diffusion during the sintering process.

Durable Hydrophilic Modification of Wool Scales with Reactive Surfactants in Saturated Neutral Salt System

In this study, a new reactive surfactant was synthesized from cyanuric chloride and Jeffamine ED-600 or ED-2003, and then applied to the pre-reduced wool fabric in saturated neutral salt solution at low temperature. This treatment condition inhibited the wool swelling, making the surfactant mainly covalently bond on the scales of wool. The structure of surfactant was confirmed by 13C NMR, and the modified wool fabrics were characterized by FTIR-ATR, XPS, and SEM after carefully washing with acetone and water. The wettability, liquid transport ability, antistatic and mechanical properties of the modified wool fabrics were also investigated. The results suggested that this modification method could significantly improve the hydrophilicity of wool surface, enhance the transport ability of liquid through the fabric and increase the antistatic properties of the fabric under low humidity conditions. Importantly, the modified fabric has robust washing fastness, with no serious damage to wool.

Pulsed Laser-Based Hybrid Microscribing of Cu and Al in Salt Solution

Abstract The influence of a subnanosecond pulsed laser-based scribing of copper (Cu) and aluminum (Al) in salt solutions (NaCl and KCl) on the formation of microchannels is reported. This technique allows laser scribing along with selective etching of Cu and Al thin films. The focused laser beam can elevate the surface temperature on the sample and hence the chemical reaction rate, resulting in combined ablation with selective-area etching. The depth of microchannels in Cu and Al films is increased by 3–5 μm using the proposed hybrid technique. The average surface roughness values in the microchannel are decreased compared to that of scribing in water and air. The hybrid approach of laser-based scribing combined with electrochemical etching in neutral salt solutions allows uniform channel with almost no redeposit layer and debris on the channel edges. Further, an approach wherein, an application of direct current (DC) voltage (1.2 V) between the tool and the workpiece while laser scribing of Cu and Al in salt solution was demonstrated to improve the channel depth by few micrometers. This hybrid machining technique has also resulted in a reduction in the surface oxidation near the laser-ablated zone compared to that observed in air and water-based experiments.

FTIR Spectroscopy Study of the Secondary Structure Changes in Human Serum Albumin and Trypsin under Neutral Salts.

The effect of neutral salts on protein conformation was first analyzed by Hofmeister in 1888, however, even today this phenomenon is not completely understood. To clarify this effect, we studied changes in the secondary structure of two proteins: human serum albumin with predominantly α-helical structure and porcine pancreas β-trypsin with the typical β-structural arrangement in aqueous solutions of neutral salts (KSCN, KCl, (NH4)2SO4). The changes in the secondary structure were studied at 23 °C and 80 °C by using the second derivative deconvolution method of the IR spectra. Our results demonstrated that the ability of the salts to stabilize/destabilize these two proteins correlates with the Hofmeister series of ions. At the same time, some exceptions were also observed. The destabilization of the native structures of both α-helical albumin and β-structural trypsin upon interaction with neutral salts leads to the formation of intermolecular β-sheets typical for amyloid fibrils or amorphous aggregates. Thus, our quantitative FTIR-spectroscopy analysis allowed us to further clarify the mechanisms and complexity of the neutral salt actions on protein structures which may lead to strategies preventing unwelcome misfolding of proteins.