Poly Aspartic Acid Research Articles

Study on the Mechanism of Wellbore Blockage and Scaling Trend Prediction of Keshen Block

Located in the Kuqa foreland basin, Tarim Basin, the Xinkeshen gas field is a rare ultra-deep and ultra-high-pressure fractured tight sandstone gas reservoir. During the development process, the fluid in the well migrates from the bottom hole to the ground. Due to the huge temperature drop and pressure drop in the wellbore, salting-out and scale-out occur in the well to destroy the oil and gas flow channel, resulting in a decrease in gas production in the well and seriously affecting the normal production of the oil field. Aiming at the problem of wellbore scaling and blockage in the Keshen gas field, this paper takes the wellbore of the Keshen block as the research object. After analyzing the composition of produced water and scale in the wellbore, the solution of ‘fixing scale, clarifying mechanism, early prediction, and fine treatment’ is formulated, and the analysis and evaluation technology of the scale formation process and the prediction model of the gas well model are formed. The wellbore blockage in Keshen block is composed of iron oxide, calcium carbonate crystal, calcite crystal, and wellbore steel falling off due to electrochemical corrosion. It is indicated that the scale attached to the steel sheet causes electrochemical corrosion of the steel sheet, resulting in ‘hydrogen embrittlement’, resulting in the bubbling and falling off of the wellbore steel. Through simulation, it is found that the amount of fouling increases with the increase in wellbore depth, and the amount of fouling is 1.97 kg/d at 6800 m, which is in good agreement with the actual situation. Based on the temperature and pressure curves in the wellbore, the simulation results show that the corrosion rate reaches the highest value of 6.37 mm/yr at the depth of 3400 m. Because of the above problems, a polyaspartic acid scale inhibitor with a scale inhibition rate of 98.9% for wells in Keshen block was synthesized. It has important guidance and reference significance for the accurate treatment of scaling problems in the Keshen gas well.

Polyaspartic Acid Urea Increased Maize Yield by Enhancing Leaf N Turnover Efficiency and Soil Microbial Diversity

The release rates of different nitrogen (N) fertilizers and their matching with plant demand determine crop yields. A field experiment was conducted to investigate the effect of using no fertilizer (N0), regular urea applied at rates of 180 kg ha−1 (N180) and 240 kg ha−1 (N240), controlled-release urea applied at a rate of 180 kg ha−1 (H180), and polyaspartic acid urea (PASP) on maize seed yield, soil microbial community diversity, and leaf N-converting enzymes. XianYu 688 was selected as the test maize variety. All cobs in the sample plots were collected per unit area to estimate maize yield. The enzyme-linked immunosorbent assay (ELISA) was used to determine leaf N-converting enzyme activities. Soil DNA was extracted using the Power Max Soil DNA Isolation Kit and subsequently sequenced using the Illumina HiSeq platform (PE 2500) to determine the microbial diversity and communities. The results showed that the highest seed yields were obtained under N240 and PASP180 treatments. The N-partial factor productivity of the PASP180 fertilizer was significantly higher than that of the other treatments. PASP treatment significantly increased maize seed yield due to the potential of storing more N in the ear leaves. Additionally, partial N productivity showed a significant positive correlation with the soil microbial Shannon, Chao1, and ACE indices, indicating that increased soil microbial diversity promoted N efficiency in maize. Further analysis revealed that PASP treatment increased seed yield by promoting leaf N-converting enzyme activity and soil microbial diversity. The results revealed that nitrate reductase (NR), glutamate synthase (GOGAT), and glutaminase (GLNS) enzyme activities in maize leaves were higher under the PASP treatment than under other fertilizer treatments. The PASP treatment significantly enhanced soil microbial diversity at different maize stages. Our study revealed the effects of using different N fertilizers on seed yield by examining their impact on soil microbial diversity and leaf N-converting enzyme activity. This study provides essential insights into maize production and soil fertility maintenance in the North China Plain.

Preparation and scale inhibition performance of modified polyaspartic acid (M-PASP)

Modified polyaspartic acid (M-PASP) was synthesized by modifying ammonia- polysuccinimide (ammonia-PSI) through a ring-opening reaction using a modifier derived from ethylenediamine, maleic anhydride, and NaOH. In addition to M-PASP, conventional polyaspartic acid (PASP) was also synthesized for comparison. The structure of conventional PASP and M-PASP were characterized by FT-IR and 1H NMR. The influence of raw materials ratio, reaction temperature and reaction time on the intrinsic viscosity of M-PASP were investigated in detail. The static scale inhibition method was used to evaluate the scale inhibition performance. The results showed that M-PASP exhibited significantly superior scale inhibition performance against CaCO3 compared to conventional PASP. Additionally, it was observed that the scale inhibition rate of M-PASP on CaCO3 increased with increasing intrinsic viscosity. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to examine the surface morphology and structure of CaCO3 crystals, respectively. The results revealed that the addition of M-PASP led to a reduction in the grain size of CaCO3 crystals and disruption of their surface morphology. In addition, molecular dynamics (MD) simulation was utilized to analyze the interaction mechanism between the polymers and calcium carbonate crystals. Based on the findings, it was postulated that the scale inhibition mechanism of M-PASP against CaCO3 involves a comprehensive interplay of several factors, including chelation solubilization, dispersion aggregation and lattice distortion.

Synergy effect of polyaspartic acid and D-phenylalanine on corrosion inhibition caused by Desulfovibrio vulgaris

Microbiologically influenced corrosion (MIC) poses a threat to various fields, particularly in piping and cooling water systems. As a green corrosion inhibitor, polyaspartic acid (PASP) faces challenges in achieving the intended corrosion inhibition against MIC due to biofilm. Therefore, mitigating biofilm might be the key to improving the corrosion inhibition of PASP. D-Phenylalanine (D-Phe) was selected as an enhancer to promote the inhibition of PASP on MIC caused by Desulfovibrio vulgaris due to its potential role in biofilm formation in this work. The joint application of PASP and D-Phe reduced the corrosion rate by 76.54% and obviously decreased the depth of corrosion pits with the maximum depth at 0.95 µm. Also, fewer cells adhered to the coupon surface due to the combined action of PASP and D-Phe, leading to thin and loose biofilm. Besides, both cathodic and anodic reactions were retarded with PASP and D-Phe, resulting in a low corrosion current at 0.530 × 10−7 A/cm2. The primary synergy mechanism is that D-Phe promoted the formation of PASP protective film via decreasing bacterial adhesion and thus inhibited electrochemical reaction and electron utilization of cells from metal surface. This study introduces a novel strategy to augment the effectiveness of PASP in inhibiting MIC.

Extraction of heavy metals from copper tailings by ryegrass (Lolium perenne L.) with the assistance of degradable chelating agents

Heavy metal contamination is an urgent ecological governance problem in mining areas. In order to seek for a green and environmentally friendly reagent with better plant restoration effect to solve the problem of low efficiency in plant restoration in heavy metal pollution soil. In this study, we evaluated the effects of three biodegradable chelating agents, namely citric acid (CA), fulvic acid (FA) and polyaspartic acid (PASP), on the physicochemical properties of copper tailings, growth of ryegrass (Lolium perenne L.) and heavy metal accumulation therein. The results showed that the chelating agent application improved the physicochemical properties of copper tailings, increased the biomass of ryegrass and enriched more Cu and Cd in copper tailings. In the control group, the main existing forms of Cu and Cd were oxidizable state, followed by residual, weak acid soluble and reducible states. After the CA, FA or PASP application, Cu and Cd were converted from the residual and oxidizable states to the reducible and weak acid soluble states, whose bioavailability in copper tailings were thus enhanced. Besides, the chelating agent incorporation improved the Cu and Cd extraction efficiencies of ryegrass from copper tailings, as manifested by increased root and stem contents of Cu and Cd by 30.29–103.42%, 11.43–74.29%, 2.98–110.98% and 11.11–111.11%, respectively, in comparison with the control group. In the presence of multiple heavy metals, CA, FA or PASP showed selectivity regarding the ryegrass extraction of heavy metals from copper tailings. PCA analysis revealed that the CA-4 and PASP-7 treatment had great remediation potentials against Cu and Cd in copper tailings, respectively, as manifested by increases in Cu and Cd contents in ryegrass by 90.98% and 74.29% compared to the CK group.

Equilibrium interactions of biomimetic DNA aptamers produce intrafibrillar calcium phosphate mineralization of collagen

Native and biomimetic DNA structures have been demonstrated to impact materials synthesis under a variety of conditions but have only just begun to be explored in this role compared to other biopolymers such as peptides, proteins, polysaccharides, and glycopolymers. One selected DNA aptamer has been explored in calcium phosphate and calcium carbonate mineralization, demonstrating sequence-dependent control of kinetics, morphology, and crystallinity. This aptamer is here applied to a biologically-relevant bone model system that uses collagen hydrogels. In the presence of the aptamer, intrafibrillar collagen mineralization is observed compared to negative controls and a positive control using well-studied poly-aspartic acid. The mechanism of interaction is explored through affinity measurements, kinetics of calcium uptake, and kinetics of aptamer uptake into the forming mineral. There is a marked difference observed between the selected aptamer containing a G-quadruplex secondary structure compared to a control sequence with no G-quadruplex. It is hypothesized that the equilibrium interaction of the aptamer with calcium-phosphate precursors and with the collagen itself leads to slow kinetic mineral formation and a morphology appropriate to bone. This points to new uses for DNA aptamers in biologically-relevant mineralization systems and the possibility of future biomedical applications. Statement of significanceCollagen is the protein structural component that mineralizes with calcium phosphate to form durable bone. Crystalline calcium phosphate must be infused throughout the collagen fiber structure to produce a strong material. This process is assisted by soluble proteins that interact with both calcium phosphate precursors and the collagen protein and has been proposed to follow a polymer-induce liquid precursor (PILP) model. Further understanding of this model and control of the process through synthetic, biomimetic molecules could have significant advantages in biomedical, restorative procedures. For the first time, synthetic DNA aptamers with specific secondary structures are here shown to influence and direct collagen mineralization. The mechanism of this process has been studied to demonstrate an important equilibrium between the DNA aptamer, calcium phosphate precursors, and collagen.

Syntheses, properties and mechanistic studies of 8-aminooctanoic acid-modified polyaspartic acid polymers for calcium scale inhibition

The anti-scaling agent poly(aspartic acidic) (PASP) polymers had became a hot research topic based on its peptide bond structures with degradation characteristics. However, it was difficult to control the chain length distributions of the synthesized products, which led to difficulty in determining the scaling mechanism for the peptide bond products. In this paper, PASP/8AC graft modified polymers with a narrow dispersity (Ð) and controllable chain lengths was synthesized via a simple two-step method, and 8-aminooctanoic acid (8AC) was introduced into the peptide bond structure of PASP with main chain lengths of 12. The effects of the side-chain lengths and functional groups on the scale inhibition mechanism were determined. The static scale inhibition results showed that the grafted products had significantly improved scale inhibition efficiencies at low concentrations and good temperature and time stabilities. The inhibition rate for CaSO4 scaling was increased by almost 60 % at a concentration of 3 mg/L. At 5 mg/L, the inhibition rate for CaCO3 scaling was increased by 36 %. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) showed that side chain length extensions improved calcium ion chelation by the PASP and increased calcium scale lattice distortion. This study verified the effects of side chains on PASP scale inhibition and its mechanism. This is of great importance in designing new green water treatment agents.

A recurrent neural network for adaptive filtering in terahertz time-domain spectroscopy

System interferences such as noise and background information in terahertz time-domain spectroscopy (THz-TDS) add difficulty to spectral signal analysis and affect the accuracy of component identification. In this paper, we proposed an adaptive filter based on a recurrent quantum neural network (RQNN) to process the THz-TDS signal. RQNN is a network architecture guided by quantum mechanics, for adaptive filtering of THz-TDS signal. Six pure substances, ferric sulfate, ferrous sulfate, Prussian blue, agarose, polylysine and sodium of polyaspartic acid were used as test samples. The TDS signals of the six samples were filtered with RQNN and five competing filters. Optical constants including refractive index and absorption coefficient were calculated from raw THz signal and filtered THz signal. Peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) were calculated between the optical constants calculated before and after filtering as evaluation indicators. Results revealed that RQNN could better eliminate the noise in THz-TDS signals, and retain the characteristic peaks in the calculated optical constants simultaneously. In terms of PSNR and SSIM, RQNN-filtered THz-TDS signals demonstrated higher values than those of the competing filters. The RQNN proposed in this paper can be used as an adaptive filter for noise filtering and signal extraction of THz-TDS signal, with advantages above traditional filtering algorithms.

Polyaspartic acid, an eco-friendly regulator for the improvement of coking coal flotation: applications and mechanism

ABSTRACT In this study, a novel approach is to apply polyaspartic acid (PASP) as an eco-friendly regulator for the flotation of coking coal, which is different from the conventional use of oil collectors only. Flotation trails showed that adding PASP contributes to a two-way improvement in the yield and ash content of clean coal. SEM-EDS observations directly revealed that adding PASP significantly reduces the coating of high-ash fine slimes on the surface of low-ash coal particles. Contact angle detections and zeta potential analysis presented that the preferential adsorption of PASP hardly affects the adsorption of sodium oleate (NaOL) on the surface of low-ash coal particles but significantly weakens the adsorption of NaOL on the surface of high-ash fine slimes, leading to a remarkably hydrophobic difference. Particle interaction energy calculations verified that adding PASP enlarges the energy barrier between low-ash coal particle and high-ash fine slime. Hence, it can be arrived that the preferential adsorption of PASP affects the adsorption of NaOL on the surface of high-ash fine slime, widens the hydrophobic difference, enlarges the energy barrier between low-ash coal particle and high-ash fine slime, reduces the high-ash fine slime coating, therefore leading to a better flotation performance of lean coal.

Preparation of environmental-benign castor oil-derived polyurethane thermal conductive structural adhesives with superior strength

Thermal conductive structural adhesives offer a robust solution for injection into the battery core of power battery packs in new energy vehicles, effectively providing filling, protecting, and facilitating timely heat dissipation. In this work, a series of castor oil (CO)-based polyurethane prepolymers with different isocyanate (NCO) contents were synthesized by a solvent-free method, which designated as Component B (curing agent) for the CO-based polyurethane (CIPU) adhesives. Polyaspartic acid ester (PAE) resin compounded with poly (tetramethylene ether glycol) (PTMG) of different molecular weights, constituted Component A of the CIPU adhesives. The effect of mass ratio of PAE to PTMG (M value) on mechanical performance of the CIPU adhesives under different curing agent conditions was investigated. The results indicated optimal overall performance for the CIPU adhesive with an M value of 3, exhibiting a tensile strength of 10.25 MPa, an elongation at break of 107.14%, and a steel-steel tensile shear strength of 4.7 MPa. Subsequently, a series of CIPU thermal conductive structural adhesives were prepared by introducing thermal conductive fillers into the optimized CIPU adhesive formula. The introduction of a 35% Boron nitride content yielded a CIPU thermal conductive structural adhesive with a thermal conductivity of 0.64 W/m·K, and a steel-steel tensile shear strength of 6.97 MPa. These innovative CIPU thermal conductive structural adhesives prepared herein are expected to be applied in the new energy automotive and electronics industries.

Sustainable Soil Additives for Water and Micronutrient Supply: Swelling and Chelating Properties of Polyaspartic Acid Hydrogels Utilizing Newly Developed Crosslinkers.

Drought and water shortage are serious problems in many arid and semi-arid regions. This problem is getting worse and even continues in temperate climatic regions due to climate change. To address this problem, the use of biodegradable hydrogels is increasingly important for the application as water-retaining additives in soil. Furthermore, efficient (micro-)nutrient supply can be provided by the use of tailored hydrogels. Biodegradable polyaspartic acid (PASP) hydrogels with different available (1,6-hexamethylene diamine (HMD) and L-lysine (LYS)) and newly developed crosslinkers based on diesters of glycine (GLY) and (di-)ethylene glycol (DEG and EG, respectively) were synthesized and characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) and regarding their swelling properties (kinetic, absorbency under load (AUL)) as well as biodegradability of PASP hydrogel. Copper (II) and zinc (II), respectively, were loaded as micronutrients in two different approaches: in situ with crosslinking and subsequent loading of prepared hydrogels. The results showed successful syntheses of di-glycine-ester-based crosslinkers. Hydrogels with good water-absorbing properties were formed. Moreover, the developed crosslinking agents in combination with the specific reaction conditions resulted in higher water absorbency with increased crosslinker content used in synthesis (10% vs. 20%). The prepared hydrogels are candidates for water-storing soil additives due to the biodegradability of PASP, which is shown in an exemple. The incorporation of Cu(II) and Zn(II) ions can provide these micronutrients for plant growth.

Statement of Retraction: Exosome-delivered BMP-2 and polyaspartic acid promotes tendon bone healing in rotator cuff tear via Smad/RUNX2 signaling pathway

Statement of Retraction: Exosome-delivered BMP-2 and polyaspartic acid promotes tendon bone healing in rotator cuff tear via Smad/RUNX2 signaling pathway

Ceragenin-mediated disruption of Pseudomonas aeruginosa biofilms.

Microbial biofilms, as a hallmark of cystic fibrosis (CF) lung disease and other chronic infections, remain a desirable target for antimicrobial therapy. These biopolymer-based viscoelastic structures protect pathogenic organisms from immune responses and antibiotics. Consequently, treatments directed at disrupting biofilms represent a promising strategy for combating biofilm-associated infections. In CF patients, the viscoelasticity of biofilms is determined mainly by their polymicrobial nature and species-specific traits, such as Pseudomonas aeruginosa filamentous (Pf) bacteriophages. Therefore, we examined the impact of microbicidal ceragenins (CSAs) supported by mucolytic agents-DNase I and poly-aspartic acid (pASP), on the viability and viscoelasticity of mono- and bispecies biofilms formed by Pf-positive and Pf-negative P. aeruginosa strains co-cultured with Staphylococcus aureus or Candida albicans. The in vitro antimicrobial activity of ceragenins against P. aeruginosa in mono- and dual-species cultures was assessed by determining minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). Inhibition of P. aeruginosa mono- and dual-species biofilms formation by ceragenins alone and in combination with DNase I or poly-aspartic acid (pASP) was estimated by the crystal violet assay. Additionally, the viability of the biofilms was measured by colony-forming unit (CFU) counting. Finally, the biofilms' viscoelastic properties characterized by shear storage (G') and loss moduli (G"), were analyzed with a rotational rheometer. Our results demonstrated that ceragenin CSA-13 inhibits biofilm formation and increases its fluidity regardless of the Pf-profile and species composition; however, the Pf-positive biofilms are characterized by elevated viscosity and elasticity parameters. Due to its microbicidal and viscoelasticity-modifying properties, CSA-13 displays therapeutic potential in biofilm-associated infections, especially when combined with mucolytic agents.

Polyaspartic acid increases potassium content and reduces the ratio of total sugar to nicotine in tobacco leaves

Tobacco is an important cash crop in China, but the low potassium (K) content and high ratio of total sugar to nicotine in tobacco leaves have seriously affected the quality of tobacco leaves. As a fertilizer synergist, polyaspartic acid (PASP) can improve the K content in tobacco leaves, but it is unknown how it affects the K content in different parts of tobacco leaves, and how PASP affects the ratio of total sugar to nicotine in tobacco leaves has not been reported. Therefore, “Zhongyan 100” was selected for pot experiments with 5 different PASP addition levels: CK (0.0 %), P1 (0.1 %), P2 (0.2 %), P3 (0.4 %) and P4 (0.6 %), to reveal the effects of PASP on tobacco growth, K content, sugar content, nicotine content and the ratio of total sugar to nicotine in different tobacco parts, and determine the optimal PASP dosage for regulating the K content and the ratio of total sugar to nicotine in tobacco. The results showed that P1 (0.1 %) and P2 (0.2 %) only had slighter effects on tobacco growth and quality, while P3 (0.4 %) and P4 (0.6 %)treatments significantly promoted dry matter accumulation, increased K and nicotine content in leaves, decreased reducing sugar and total soluble sugar content in leaves, thereby reducing the ratio of total sugar to nicotine in tobacco leaves, especially in upper leaves. Considering the economic cost savings, 0.4% PASP was determined as the best application level to improve the growth and quality of tobacco. Thus, proper application of PASP is beneficial to improve tobacco leaf quality and reduce chemical K fertilizer application, thereby decreasing agricultural environmental risks of chemical fertilizer and alleviating the rapid depletion of potash in the world.

Optimization of microencapsulation of polyaspartic acid ester into UV curable epoxy‐acrylate resin using Taguchi method of experimental design

AbstractDue to fast reaction with isocyanates, polyaspartic acid esters (PAAE) can be used for the development of microcapsules for self‐healing coatings. Microcapsules with encapsulated PAAE into shell formed by UV‐cured commercial epoxy‐acrylate resin were produced through oil‐in‐water emulsion polymerization triggered by UV light. The obtained microcapsules were characterized by FTIR, TGA, optical microscopy, and SEM. Various encapsulation parameters, including core to shell ratio, agitation speed, emulsifier type and concentration, solvent type and its concentration in the oil phase, have been selected at four different levels. Microencapsulation was optimized using Taguchi L16 parameter design approach for determination of desired outcome as larger is better (maximal core content) and nominal is better (microcapsule diameter of 50 μm). It was determined that conditions to prepare microcapsules with the highest core content and the microcapsule size close to 50 μm are rather similar requiring core‐to‐shell ratio at about 4:1, low agitation speed of 500–1000 rpm, and the use of two polymeric emulsifiers poly(vinyl alcohol) and Gum Arabic at concentration of about 2%. Primary benefits of UV‐induced shell formation during microencapsulation of active compounds are remarkably shorter time of the process and possibilities to reach high core content and prepare microcapsules of desirable size.

Efficient removal of Hg2+, Cu2+ and Cd2+ from aqueous solutions with polyaspartic acid: Influencing factors and mechanism analysis

The removal rates of polyaspartic acid (PASP) for Hg2+, Cu2+ and Cd2+ were evaluated, and the complexes formed after the reaction were characterised. With increasing PASP dosage, the removal rate increased. At pH 5.0–9.0, the removal rates increased as the pH increased. The removal rates of three heavy metal ions from Cl− ions were higher than those from NO3– ions. The removal amounts of Hg2+, Cu2+ and Cd2+ by PASP were 1058.46, 203.07 and 459.20 mg·g−1, respectively. The SEM images reflected the significant interactions between the heavy metal ions and PASP. The FTIR spectra revealed that carboxylate and nitrogen were the significant groups in the reactions of PASP with Hg2+ and Cu2+, and carboxylate was the significant group in the reaction of PASP with Cd2+. Overall, the results demonstrate that PASP is a promising candidate for removing Hg2+, Cu2+ and Cd2+ from aqueous solutions.

Intrafibrillar mineralization of type I collagen with calcium carbonate and strontium carbonate induced by polyelectrolyte-cation complexes.

Calcium carbonate (CaCO3), possessing excellent biocompatibility, bioactivity, osteoconductivity and superior biodegradability, may serve as an alternative to hydroxyapatite (HAp), the natural inorganic component of bone and dentin. Intrafibrillar mineralization of collagen with CaCO3 was achieved through the polymer-induced liquid precursor (PILP) process for at least 2 days. This study aims to propose a novel pathway for rapid intrafibrillar mineralization with CaCO3 by sequential application of the carbonate-bicarbonate buffer and polyaspartic acid (pAsp)-Ca suspension. Fourier transform infrared (FTIR) spectroscopy, zeta potential measurements, atomic force microscopy/Kelvin probe force microscopy (AFM/KPFM), and three-dimensional stochastic optical reconstruction microscopy (3D STORM) demonstrated that the carbonate-bicarbonate buffer significantly decreased the surface potential of collagen and CO32-/HCO3- ions could attach to collagen fibrils via hydrogen bonds. The electropositive pAsp-Ca complexes and free Ca2+ ions are attracted to and interact with CO32-/HCO3- ions through electrostatic attractions to form amorphous calcium carbonate that crystallizes gradually. Moreover, like CaCO3, strontium carbonate (SrCO3) can deposit inside the collagen fibrils through this pathway. The CaCO3-mineralized collagen gels exhibited better biocompatibility and cell proliferation ability than SrCO3. This study provides a feasible strategy for rapid collagen mineralization with CaCO3 and SrCO3, as well as elucidating the tissue engineering of CaCO3-based biomineralized materials.

Effect of polyaspartic acid as an environmental-friendly depressant on flotation separation of chalcopyrite from arsenopyrite

The selection of environmental-friendly and high-efficiency depressants is a major research priority for removing arsenic from copper concentrates. The polyaspartic acid (PASP, (C4H6O3N) n) was used for the selective separation of chalcopyrite from arsenopyrite to explore the depression mechanism of PASP using micro-flotation experiments, contact angle measurements, zeta potential measurements, fourier transform infrared spectroscopy (FT-IR), local electrochemical impedance (LEIS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The flotation results showed that recovery of chalcopyrite reached up 90.18 %, while the recovery of arsenopyrite was only 23.48 %, when the PASP was added. The contact angle measurements and zeta potential measurements showed that PASP selectively adsorbed on the surface of arsenopyrite, but was not adsorbed on the surface of chalcopyrite. The FT-IR tests further confirmed that the adsorption was chemical adsorption. The LEIS tests revealed that the conductivity of arsenopyrite surface increased with the addition of PASP, while chalcopyrite was almost unaffected. The ToF-SIMS analyses illustrated that the arsenopyrite with Fe and As sites was reacted with —NH– in the structure of PASP to form stable complexes. Finally, the mechanism diagram was designed to provide insight into the adsorption mechanism of PASP on the surface of arsenopyrite and its selective inhibition of arsenopyrite.

Morphology transformation of Na2SO4 from prism into dendrite enhanced desalination efficiency in sandstone by biodegradable polycarboxylate modifiers

The salt decay on the surface of stone cultural relics is the greatest damage to its loaded information. Polycarboxylate modifiers can reduce salt crystallization pressure and/or change crystal habits, thereby becoming a new method for controlling salt crystallization damage in pores. However, the lack of precise regulation of crystal morphology by modifier and the unclear relationship between modifier and crystal transformation during salt growth hinder its practical application. Herein, diethylenetriamine pentamethylene phosphonic acid (DTPMP), phosphorus-free, green polyaspartic acid (PASP) and polyepoxysuccinic acid (PESA), as well as three composite modifiers composed of DTPMP and PESA (M-1:9, M-2:8, M-3:7) were systematically investigated. Video microscope, scanning electron microscope, and X-ray diffraction showed that the addition of these modifier could obviously transform the crystal morphology of sodium sulfate(thenardite) from prism into dendrite, which was related to the significant change in the intensity ratios of corresponding peaks on the different crystal planes. Molecular dynamics simulations were conducted to investigate the interactions of PASP and PESA on different surfaces of sodium sulfate, revealing that the crystal transformation of sodium sulfate was mainly influenced by the coordination/adsorption effect of the modifiers on the (010) plane. All modifiers were used for sandstone desalination, and the clean and desalted sandstones were analyzed for desalting efficiency, colorimetry and porosity, which showed that PESA, PASP and composite modifier M-3:7 all promoted the precipitation of sodium sulfate on the surface. Especially, composite modifier M-3:7 prefers to change the crystallization and morphology of sodium sulfate from prism into dendritic flower, which can be used to protect to sandstone cultural relics from salt damage.

Polymer-induced liquid precursors: How are they being used and what is the effect on dentin remineralization? A scoping review

To identify the effectiveness of polymer-induced liquid precursors (PILP) on dentin remineralization and the assessment approaches used to evaluate remineralization. The analyses were done into six stages: (1) Identifying the research question; (2) Identifying the studies; (3) Selecting relevant studies; (4) Plotting the data; (5) Reporting results; and (6) Risk of bias. The searches were carried out in the following databases: PubMed, Web of Science, and Scopus. A total of 247 articles were identified in the electronic database search. After applying the eligibility criteria, only 12 articles were included for data extraction. The outcomes of dentin remineralization patterns were plotted in association to PILP agent type and application mode. The intrafibrillar mineralization occurred in 78% of studies where polyaspartic acid (pAsp) was used, and 50% when the polyacrylic acid (PAA) was used. All the studies where PILP was used in a restorative material (resin composite, glass ionomer, and adhesive system)—extra and intrafibrillar mineralization pattern was found. The association of PILP agents with other materials with potential for mineralization showed beneficial results in remineralization, since they provide a medium to high concentration of calcium and phosphate. The pAsp showed better results for interfibrillar remineralization when compared to PAA. The association with Ca/P release materials or solution Ca P are essentials for mineralization via PILP agent. Further studies are needed to assess the effectiveness of remineralization through PILP agents because the level of evidence of the studies was low.