Additional Mechanisms Research Articles

Unveiling spatiotemporal distribution, partitioning, and transport mechanisms of tire additives and their transformation products in a highly urbanized estuarine region

Numerous tire additives are high-production volume chemicals that are used extensively worldwide. However, their presence and partitioning behavior remain largely unknown, particularly in marine environments. This study is the first to reveal the spatiotemporal distribution, multimedia partitioning, and transport processing of 22 tire additives and their transformation products (TATPs) in a highly urbanized estuary (n = 166). Nineteen, 18, and 20 TATPs were detectable in water, suspended particulate matter (SPM), and sediments, respectively, with total levels of 59.7–2021 ng/L, 164–6935 ng/g, and 4.66–58.4 ng/g, respectively. The multimedia partitioning mechanisms of TATPs are governed by their molecular weight, hydrophobicity, and biodegradation rate. Mass inventories coupled with model simulations have revealed that substantial quantities of TATPs accumulate within estuarine environments, and these compounds can be continuously transported into the ocean, particularly during the wet season. According to the multi-criteria evaluation approach, four and three TATPs were identified as high-priority pollutants during the dry and wet seasons, respectively. Unexpectedly, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone was only listed as a medium-priority pollutant. This study underscores the importance of marine surveillance and advocates for particular attention to these ubiquitous but underexplored TATPs in future studies.

Effect of additives on the microstructure and properties of pulsed electrodeposited copper foils

ABSTRACT A low-roughness ultra-thin copper foil was prepared by pulsed electrodeposition with a duty cycle 60%, pulse frequency of 600 Hz on titanium. The influence of sodium 3,3'-dithiodipropane sulphonate (SPS), hydroxyethyl cellulose (HEC), gelatin and collagen additives on the microstructure, mechanical properties and electrochemical behaviour of electrolytic copper foil was explored. Furthermore, the reaction mechanism of SPS and collagen additives on electrodeposited copper were discussed. The results showed that at 0.08 g L−1 collagen concentration, the lowest thickness, the highest microhardness and the optimal surface roughness were achieved (5.12 μm, 279.63 HV and 1.885 μm, respectively). X-ray diffraction results confirmed that electrolytic copper foils prepared when SPS was introduced into the blank solution had a preferred orientation of (220) texture, which benefitted from the synergistic effect of copper ions and additives. The intermediates formed by the additive and Cu+ occupied the active sites on the cathode surface that increased the nucleation sites for deposition. In addition, the formed complexes can act as a barrier to narrow ion deposition channels and inhibit the growth of Cu ions.

Ca2+-dependent vesicular and non-vesicular lipid transfer controls hypoosmotic plasma membrane expansion.

Robust coordination of surface and volume changes is critical for cell integrity. Few studies have elucidated the plasma membrane (PM) remodeling events during cell surface and volume alteration, especially regarding PM sensing and its subsequent rearrangements. Here, using fission yeast protoplasts, we reveal a Ca2+-dependent mechanism for membrane addition that ensures PM integrity and allows its expansion during acute hypoosmotic cell swelling. We show that MscS-like mechanosensitive channels activated by PM tension control extracellular Ca2+ influx, which triggers direct lipid transfer at endoplasmic reticulum (ER)-PM contact sites by conserved extended-synaptotagmins and accelerates exocytosis, enabling PM expansion necessary for osmotic equilibrium. Defects in any of these key events result in rapid protoplast rupture upon severe hypotonic shock. Our numerical simulations of hypoosmotic expansion further propose a cellular strategy that combines instantaneous non-vesicular lipid transfer with bulk exocytic membrane delivery to maintain PM integrity for dramatic cell surface/volume adaptation.

SDBS-AEO Mixture for Triton X-100 Replacement: Surface Activity and Application in Biosensors.

Triton X-100 (TX-100) is a commonly used surfactant in the manufacture of biosensors. The factors limiting the use of TX-100 in biosensors are environmental concerns. In this study, the binary system of sodium dodecyl benzene sulfonate (SDBS) and fatty alcohol-polyoxyethlene ether (AEO) was investigated from the physicochemical principle of surfactant interaction and its application in biosensors. The results demonstrated that a mixture of SDBS and AEO at an appropriate molar ratio had a comparable activity to TX-100 in terms of surface activity, micelle formation, dynamic adsorption, foaming, emulsifying, and cell permeability. Theory and experimentation support the idea that SDBS-AEO might take the place of TX-100 in the manufacturing of biosensors. This study contributes to the development of alternatives to TX-100 and provides a new perspective for an in-depth study of the interaction mechanism of additives in biosensor design.

Serum-free medium for recombinant protein expression in insect cells.

The baculovirus expression vector system (BEVS) has been widely used to produce recombinant proteins because of several advantages, such as eukaryotic post-translational modifications similar to those in mammalian cells, high expression levels and safety, and large gene capacity. Usually, insect cell culture requires 5%‒10% fetal bovine serum, which has many adverse effects, including high cost, heterogeneity between batches, complex composition, and pollution risks. Therefore, serum-free medium (SFM) is indispensable for the production of recombinant proteins in insect cell culture. Here, the most commonly used insect cell lines and three insect cell media, namely basic medium, SFM, and chemically defined medium, are summarized. The basic components of insect cell SFM are similar to those of other cells but contain special components. The components, functions, and issues of different SFM used for insect cell culture are reviewed. In recent years, some special additives have been demonstrated to increase recombinant protein expression yield and quality in BEVS, and the functions and possible mechanisms of small-molecule additives are reviewed herein. Finally, future perspectives of SFM used in BEVS for recombinant protein production are discussed.

Frozen dough steamed products: Deterioration mechanism, processing technology, and improvement strategies.

Fresh dough products lead to instability in product quality, high production costs, and more production time, which seriously affects the industrial production of the food industry. The frozen dough technology mitigates the problems of short shelf-life and easy deterioration of quality during storage and transportation. It has shown a series of advantages in large-scale industrialization, high-quality standardization, and chain operation. However, the further development of frozen dough is restricted by the deterioration of the main components (gluten, starch, and yeast) caused by freezing. This review summarizes the main production process of frozen steamed bread and buns, and the deterioration reasons for the main component of frozen dough. The improvement mechanisms of raw ingredients, processing technology, processing equipment, and additives on frozen dough quality were analyzed from the perspective of improving gluten network integrity and yeast freeze tolerance. From prefermented frozen raw to steamed products without thawing has become the preferred production process to improve production efficiency. Wheat flour mixed with other flour can maintain the gluten network continuity of frozen dough. The freeze tolerance of yeast was improved by treatment with yeast suspension, yeast cell encapsulation, screening hybridization, and genetic engineering. Process optimization and new technology-assisted fermentation and freezing effectively reduce freezing damage. Various additives improve the freeze resistance of the gluten-starch matrix by promoting protein cross-linking and inhibiting water migration. In addition, ice structural proteins and ice nucleating agents have been proven to change the growth morphology and formation temperature of ice crystals. More new technologies and additive synergies need to be further explored.

Application of modified and toughened admixtures in well cementing slurry: Progress and challenges

Cementing, as an important part of the petroleum industry, plays a crucial role in ensuring the normal production and development of oil and gas resources. However, due to the brittle nature of Portland cement, it is prone to micro-cracks when subjected to downhole impact or vibration, which affects normal operations. Moreover, conventional elastic particles have a significant impact on the performance of cement paste, prompting people to continuously research new toughening admixtures. This article reviews the mechanism of toughening additives for oil well cement, the research status of physical toughening agents (fibers/whiskers, graphene) and polymer toughening agents (latex, epoxy resin, asphalt), aiming to provide reference and guidance for the development of new toughening additives.

Friction Mechanism of Sulfur-Containing Lubricant Additives Confined between Fe(100) Substrates.

Sulfur-containing lubricant additives can chemically react with metal surfaces under extreme conditions, such as high temperature and high pressure, forming protective films on the surfaces. However, the formation mechanisms and the friction-reducing and antiwear properties of these films remain unclear. In this study, we investigated the friction process of sulfur-containing additives confined between two iron surfaces using reactive molecular dynamics simulations. Our research revealed that in systems with a higher S/C ratio, an iron sulfide layer formed on the iron surfaces with Fe-S-Fe bridging bonds at the interface, resulting in relatively smaller friction and wear even under higher loads. However, in systems with lower S/C ratios, the presence of numerous interfacial Fe-Cn-Fe bridging bonds, caused by the hydrocarbon radicals released from the additives, led to the formation of thick amorphous shearing bands at the interface between the two substrates. In this case, the distributed sulfur atoms also exhibited some effect in reducing the shear resistance of the amorphous shearing bands due to the weak strength of S-Fe bonds compared to the strength of C-Fe bonds. These atomic-level insights help understand the antiwear characteristics of sulfur-containing lubricant additives confined between iron substrates.

Molecular dynamics simulation on the variations in characteristics of aqueous solution with diverse additives: Inspirations for binary ice preparation

Ice slurry, as a novel energy storage medium, possesses the superiority of high energy storage density. The freezing point inhibitors are employed to regulate the supercooling phenomenon of water, while the macroscopic experiments are complicated to elucidate the action mechanism. Consequently, this paper adopts molecular dynamic simulation method to investigate the mean square displacement, radial distribution function, hydrogen bonds types, hydrogen bonds number and length of water at various concentrations of ethanol, NaCl, and SiO2 additives. The results indicate that the average number of hydrogen bonds of the system composed with 600 pure water molecules is 1127.24, and the average length of hydrogen bonds is 2.33 Å. Moreover, the addition of alcoholics and chlorides inhibits the hydrogen bonds between water and water molecules, and promotes the generation of hydrogen bonds, thus weakening the diffusion motion of water molecules. Whereas, it is observed that the addition of nanoparticles leads to agglomeration in pure water system, resulting an increase in the viscosity and a decrease in the diffusion rate of the system. The proposed microscopic model can effectively depict the potential interaction mechanisms of additives and water, which is contributing to develop effective freezing point inhibitors and improve the energy utilization efficiency.

Effects of Sm2O3 and TiO2 on the performance of MgAl2O4-Si3N4 ceramics for solar thermal absorber in concentrating solar power

Aiming to further improve the properties of novel MgAl2O4-Si3N4 ceramic used as solar thermal absorbing material in concentrating solar power, effects of Sm2O3 and TiO2 on performance of the composites were investigated especially the mechanisms of different additives on microstructure and high temperature stability. The results show that both additives can accelerate sintering, reduce sintering temperature, improve the density and high temperature stability via liquid phase sintering mechanism. Besides, TiO2 can form displacement solid solution with Al2O3 to promote the sintering process. Sm2O3 is more conducive to improving the bending strength due to its function of increasing the length diameter ratio of β-Si3N4. TiO2 is more favorable for improving solar absorption owing to the distinctive absorption spectrum and large number of cation vacancy caused by substitution of Al3+ by Ti4+. MgAl2O4-Si3N4 composites with Sm2O3 and TiO2 additives have better performance than MgAl2O4-Si3N4, Si3N4 and SiC ceramics prepared via the same procedure, which makes it a certain choice for solar thermal absorbing material.

Higher alcohol acetoacetate aluminum chelates as pour point depressant and impedance reducing agent of biodiesel-diesel blends

The use of additives to improve the shortcomings of biofuels in application is one of the most economical and effective methods. In this study, a new type of tridentate higher alcohol acetoacetate aluminum chelate additive was synthesized originally and then synchronously used as pour point depressant and resistance reducing agent. The low temperature fluidity of biodiesel-diesel blends, including cloud point, cold filter plugging point and pour point could be reduced by the maximum of 6, 7 and 12 °C for B20 (20 vol% biodiesel + 80 vol% diesel), and 5, 5 and 9 °C for biodiesel after the treatment of higher alcohol acetoacetate aluminum chelate additive, named as C16-acac-Al. Furthermore, the impedance modulus determined by electrochemical impedance spectroscopy of the blends were greatly reduced after the treatment of C16-acac-Al, especially noiseless-free in the low frequency region, and the effects of temperature change on electrochemical impedance spectroscopy of treated blends was explored. At length, the mechanism on how the morphology of wax crystals affect electrochemical impedance spectroscopy of treated blends as well as the effect mechanism of the synthetic additives improving the low temperature fluidity of blends were put forward.

The influence of low temperature rise polymer on early cement hydration from the point of view of hydration kinetics and thermodynamics

The key to studying the influence mechanism of additives on the cement hydration process lies in revealing the influence process of admixtures on the evolution of chemical driving forces of relevant phases in the cement hydration process. This study is the first to adopt the Krstulovic-Dabic (K-D) kinetic model to investigate the hydration mechanism and kinetic parameters of a cement system with a low-temperature polymer (CAMC). Gibbs Energy Minimization Selektor (GEMS) was used for pore solution composition analysis of cementitious system and calculation of saturation index. The results show that the exponent and reaction rate constant of the (K-D) model decrease with the increase of hydration age and CAMC content, with K1 significantly greater than K2 and K3 being the smallest. The saturation index of calcium hydroxide (CH) and ettringite (AFt) is greater than 0, indicating that both phases are supersaturated in all samples. The transition time from supersaturation to undersaturation of gypsum is delayed, confirming the delayed consumption of gypsum by CAMC. This provides new insights into the effects of admixtures on cement hydration and the mechanisms of cement hydration.

The effect of freeze-thaw cycles and sulfuric acid attack separately on the compressive strength and microstructure of 3D-printed air-entrained concrete

3D-printed concrete (3DPC) is a promising technique for constructing structures and intricate designs. To ensure the successful performance of these structures throughout their service life, it is essential to understand their long-term properties and durability. While the use of air-entraining additives can enhance the durability of concrete against freeze-thaw cycles, investigating their impact on other properties is crucial. This study examines the effect of freeze-thaw cycles and sulfuric acid attack on the durability of 3D-printed concrete containing air-entraining additives. The results indicate that, in addition to improving resistance to freeze-thaw cycles, air-entraining additives also increases resistance to sulfuric acid attack. The drop in compressive strength of the samples containing air-entrained additive (0.08–0.12 % AEA) is 1.4–5.3 % less than the control samples against the freezing and thawing cycles. Examining the mechanisms of action of these invasive agents also shows this. Creating intentional voids to reduce the internal pressure of water expansion during freezing and reducing the number and width of possible microcracks are the dominant mechanisms of air-entraining additives against freeze-thaw cycles. Besides, their performance mechanisms during acid attacks are somewhat similar. Analysis of elements created in the matrix of the samples after acid attack indicates a decrease in calcium concentration and an increase in silica concentration. Among the observed reactions, the second reaction prevails, leading to the breakdown of the C-S-H structure into gypsum and silica hydroxide. This phenomenon is associated with changes in acid concentration. However, the presence of air bubbles causes surplus plate-like Calcium hydroxide crystals resulting from the elevated cement content in printed mixes to form within these bubbles, making them susceptible to damage and fracture during freeze-thaw and acid attacks.

Implications for the Hydrogenation of Propyne and Propene with Parahydrogen due to the in situ Transformation of Rh2C to Rh0/C.

NMR spectroscopy studies using parahydrogen-induced polarization have previously established the existence of the pairwise hydrogen addition route in the hydrogenation of unsaturated hydrocarbons over heterogeneous catalysts, including those based on rhodium (Rh0). This pathway requires the incorporation of both hydrogen atoms from one hydrogen molecule to the same product molecule. However, the underlying mechanism for such pairwise hydrogen addition must be better understood. The involvement of carbon, either in the form of carbonaceous deposits on the surface of a catalyst or as a metal carbide phase, is known to modify catalytic properties significantly and thus could also affect the pairwise hydrogen addition route. Here, we explored carbon's role by studying the hydrogenation of propene and propyne with parahydrogen on a Rh2C catalyst and comparing the results with those for a Rh0/C catalyst obtained from Rh2C via H2 pretreatment. While the catalysts Rh2C and Rh0/C differ notably in the rate of conversion of parahydrogen to normal hydrogen as well as in terms of hydrogenation activity, our findings suggest that the carbide phase does not play a significant role in the pairwise H2 addition route on rhodium catalysts.

Insight into the Manipulation Mechanism of Polymorphic Transformation by Polymers: A Case of Cimetidine.

Employing polymer additives is an effective strategy to realize the manipulation of polymorphic transformation. However, the manipulation mechanism is still not clear, which limit the precise selection of polymeric excipients and the development of pharmaceutical formulations. The solubility of cimetidine (CIM) in acetonitrile/water mixtures were measured. And the polymorphic transformation from CIM form A to form B with the addition of different polymers was monitored by Raman spectroscopy. Furthermore, the manipulation effect of polymers was determined based on the results of experiments and molecular simulations. The solubility of form A is consistently higher than that of form B, which indicate that form B is the thermodynamically stable form within the examined temperature range. The presence of polyvinylpyrrolidone (PVP) of a shorter chain length could have a stronger inhibitory effect on the phase transformation process of metastable form, whereas polyethylene glycol (PEG) had almost no impact. The nucleation kinetics experiments and molecular dynamic simulation results showed that only PVP molecules could significantly decrease the nucleation rate of CIM, due to the ability of reducing solute molecular diffusion and solute-solute molecular interaction. A combination of crystal growth rate measurements and calculations of the interaction energies between PVP and the crystal faces of CIM indicate that smaller molecular weight PVP can suppress crystal growth more effectively. PVP K16-18 has more impact on the stabilization of CIM form A and inhibition of the phase transformation process. The manipulation mechanism of polymer additives in the polymorphic transformation of CIM was proposed.

Isomerization Engineering of Solid Additives Enables Highly Efficient Organic Solar Cells via Manipulating Molecular Stacking and Aggregation of Active Layer.

Morphology control is crucial in achieving high-performance organic solar cells (OSCs) and remains a major challenge in the field of OSC. Solid additive is an effective strategy to fine-tune morphology, however, the mechanism underlying isomeric solid additives on blend morphology and OSC performance is still vague and urgently requires further investigation. Herein, two solid additives based on pyridazine or pyrimidine as core units, M1 and M2, are designed and synthesized to explore working mechanism of the isomeric solid additives in OSCs. The smaller steric hindrance and larger dipole moment facilitate better π-π stacking and aggregation in M1-based active layer. The M1-treated all-small-molecule OSCs (ASM OSCs) obtain an impressive efficiency of 17.57%, ranking among the highest values for binary ASM OSCs, with 16.70% for M2-treated counterparts. Moreover, it is imperative to investigate whether the isomerization engineering of solid additives works in state-of-the-art polymer OSCs. M1-treated D18-Cl:PM6:L8-BO-based devices achieve an exceptional efficiency of 19.70% (certified as 19.34%), among the highest values for OSCs. The work provides deep insights into the design of solid additives and clarifies the potential working mechanism for optimizing the morphology and device performance through isomerization engineering of solid additives.

Effect of the combination of antioxidant and dispersant in traction oils on their interaction and lubricating property

Molecular dynamics simulation is utilized to reveal the interaction and lubricating property of polyisobutylsuccinimide-polyamine (PIB-PAM) dispersant and phosphorus compound (PAE3) antioxidant in two traction systems (JP1E, JP1EC). The content ratio of PIB-PAM to PAE3 is changed. The static self-assembly of additives is observed, while PIB-PAM molecules with strongly intermolecular entanglement displays a suppressive effect on the molecular diffusion. In the shear process, the adsorption of base oil on surfaces shows a non-wall-slip friction state, and the increasing shear rate causes the adsorption film thinning and the friction coefficient rise. The strong intermolecular interaction in lubricating system induces high friction resistance. The fundamental insights into the interaction mechanism of different additives are helpful for improving lubricant research and development.

Selective Crystallization of l-Histidine Metastable Polymorphs: The Role and Mechanism of Additives

Selective Crystallization of <scp>l</scp>-Histidine Metastable Polymorphs: The Role and Mechanism of Additives

Theoretical kinetic investigation of the multichannel mechanism of O(3P) atmospheric oxidation reaction of but-3-enal

Several levels of theory such as Møller-Plesset MP2, G3, and CBS-QB3, have been used in order to investigate the complex and multichannel potential energy surface of the reaction of but-3-enal with the triplet oxygen atom. The results show that the O-addition channel is dominant. The different possible pathways of oxygen atom attack are thoroughly studied to better understand and explain the reaction mechanism. Regarding the oxidation of but-3-enal by triplet oxygen O(3P), it is shown that the major thermodynamic product is H3CC(O)CH2C(O)H (P3) being the most stable for the whole reaction. However, the most favored product kinetically is H2CC(OH)CH2C(O)H (P2). For the H-abstraction second possible pathway, the most favored product both kinetically and thermodynamically is found to be P8. The activation energy and calculated rate constants are consistent with the proposed addition mechanism.

Green hydrogen prospects in Peninsular Malaysia: a techno-economic analysis via Monte Carlo simulations

According to Malaysia's National Energy Transition Roadmap, hydrogen is a critical component of the country's energy transition. However, there is a scarcity of hydrogen studies for Peninsular Malaysian states, which limits discussions on green hydrogen production. This study employs a Monte Carlo model to assess the economic and technical factors influencing the success of green hydrogen in Peninsular Malaysia. The study focuses on three target years: 2023, 2030, and 2050, representing various stages of technological development and market adoption. The levelized cost of hydrogen (LCOH) of a 1-MW Proton Exchange Membrane (PEM) electrolyzer system ranges from $5.39 to $10.97 per kg in 2023, highlighting early-stage challenges and uncertainties. A 6-MW PEM electrolyzer system could achieve an LCOH of $3.50 to $4.72 per kg by 2030, indicating better prospects. Because of technological advancements and cost reductions, a 20-MW PEM electrolyzer system could achieve an LCOH of $3.12 to $3.64 per kg in 2050. The findings indicate that the northern regions of Peninsular Malaysia have consistently low LCOH values due to favorable geographical conditions. Due to minor variations in solar capacity factors, uncertainty distributions in LCOH remain stable across different regions. Some states may face increased uncertainty, emphasizing the need for additional policy support mechanisms to mitigate risks associated with green hydrogen investments. The sensitivity analysis shows that key cost drivers are shifting, with early-stage electrolyzer investments dominating in 2023 and electricity prices becoming more important in 2030 and 2050. Future research could focus on optimizing green hydrogen systems for areas with underdeveloped green hydrogen industries. This study contributes to informed discussions about green hydrogen production by emphasizing the importance of tailored strategies that consider local conditions and highlighting the role of Peninsular Malaysia in the energy transition.