Stable Suspension Research Articles

Modified Fibrous Mass of Leather and Paper Waste for the Production of Packaging Paper and Cardboard

Recycling leather waste, which accumulates in large quantities in tanneries, and producing packaging paper with improved properties reduces the environmental burden and is at the same time economically efficient. A modified fibrous mass of waste from tanned and untanned leather scraps, waste paper, and acrylic emulsion was obtained and packaging paper based on them was produced. Alkaline modification of tanned leather waste - chrome shavings - leads to an increase in the electrokinetic potential and, accordingly, the stability of the fibrous suspension, partial hydrolysis of skin collagen occurs with the formation of new polar groups, and at the same time, the degree of cross-linking of the skin increases. In the paper composition, new intermolecular bonds are formed between cellulose and skin collagen. The microstructure, elemental composition, morphology, thermal and physical-mechanical properties of modified chrome shavings and composite paper were determined. A significant improvement has been achieved in the main parameters of paper: surface density (decrease by 16-25%), breaking load and breaking length (increase by 15-23%), number of double bends (increase by 2-6 times) in comparison with paper obtained from pure waste paper, and also to a greater extent compared to paper obtained from unmodified leather waste.

Green synthesis of silver nanoparticle using pollen extract from Tetragonisca angustula a stingless bee.

This study explores the green synthesis of silver nanoparticles (AgNPs) using a methanolic extract of fermented pollen from Tetragonisca angustula, a species of stingless bees. The AgNPs exhibit spherical morphology, low charge values, and suspension stability, with their unique composition attributed to elements from the pollen extract. Antioxidant assays show comparable activity between the pollen extract and AgNPs, emphasizing the retention of antioxidant effects. The synthesized AgNPs demonstrate antimicrobial activity against multidrug-resistant bacteria, highlighting their potential in combating bacterial resistance. The AgNPs exhibit no toxic effects on Drosophila melanogaster and even enhance the hatching rate of eggs. The study underscores the innovative use of stingless bee pollen extract in green synthesis, offering insights into the varied applications of AgNPs in biomedicine.

Stochastic response and stability analysis of nonlinear vehicle energy-regenerative suspension system with time delay

With the rapid development of new energy vehicles, a novel vehicle energy-regenerative suspension for simultaneous vibration suppression and energy harvesting has become one of the key development directions of the next generation of vehicle design. In order to improve the performance of suspension system, the time-delayed feedback control is applied to the novel suspension system subjected to different external excitation. At the same time, there are few studies related to the stochastic dynamics of nonlinear vehicle energy-regenerative suspension system with time delay. This paper studies stochastic response and stability of nonlinear vehicle energy-regenerative suspension with time-delayed feedback control under the excitation of Gaussian white noise. First of all, a stochastic dynamic model of the nonlinear vehicle energy-regenerative suspension with time delay system is established. Secondly, using the stochastic averaging method based on generalized harmonic function, the steady-state probability density function (PDF) of amplitude is obtained. The accuracy of the presented approach is verified through the comparison of analytical and numerical solutions. In addition, through combining the stochastic averaging method with the Khasminskii method, the top Lyapunov exponent (TLE) of the system is obtained, and then the influence of time delay and system parameters on the asymptotic Lyapunov stability is discussed. Finally, the effects of time delay and system parameters on system performance are also studied.

Heat Transfer Application of Nanofluids and Testing of Thermal Conductivity

In response to the growing demand for more efficient heat transfer technologies in various industrial processes, the development of nanofluids has emerged as a promising solution. Traditional heat transfer fluids like mineral oil, ethylene glycol, and water have relatively low thermal conductivities compared to solids, limiting the compactness and efficiency of heat exchangers. Nanofluids, which are created by suspending ultrafine metallic or nonmetallic solid powders in base fluids, exhibit enhanced thermal properties due to the superior thermal conductivities of solid materials. This paper reviews the preparation, thermal conductivity measurement, and influencing factors of nanofluids, with a focus on thermal conductivity as the primary driver for improved heat transfer. The preparation of nanofluids involves either a one-step or two-step method, with the two-step method being more commonly used for oxide nanoparticles (NPs) such as Al2O3, ZnO, MgO, TiO2, and SiO2. The study discusses stabilization techniques like ultrasonication and magnetic force agitation to ensure homogeneous suspension and long-term stability of the nanofluids. The thermal conductivity measurements are conducted using short hot wire (SHW) and transient hot wire (THW) techniques, with considerations of the nonsteady-state nature and potential error sources. The research underscores the importance of rigorous experimental design and accurate data analysis to address the complexities and variability in thermal conductivity measurements, ultimately contributing to the advancement of nanofluid technologies for efficient heat transfer solutions.

Production and characterisation of microfluidized olive powder

SummaryMicrofluidization has been gaining popularity as a size reduction process in recent years. In this study, microfluidization technique was used for olives to change the cell wall structure and decrease the size of oil droplets. Olive powders were produced from green, black and raw olives using freeze drying following microfluidization at 1200 bar. Antioxidant activity was not affected significantly for all powders while total phenolic content decreased for green and raw olive powders with microfluidization. Among all olive powders, the one raw olive gave the highest antioxidant activity and phenolic content. In microscopic analysis, Scanning Electron Microscope images revealed that microfluidization results in finer particles which are self‐encapsulated by trapping the oil droplets. Stability analysis through Turbi Scan and rheological measurements of the powder suspensions showed that microfluidization process enables more stable suspensions having higher water holding capacity. Herschel–Bulkley model was found for the flow behaviours of the olive powder suspensions.

Acute toxicity of copper and chromium oxide nanoparticles to Daphnia similis

Copper oxide nanoparticles (CuO NPs) are employed in antifouling paints, and chromium oxide nanoparticles (Cr2O3 NPs) have been used as a green pigment. Their extensive use can contaminate aquatic ecosystems, and the toxicological effects of these NPs to the biota are poorly known. In this study, we evaluated the acute toxicity induced by CuO and Cr2O3 NPs, comparing with CuSO4 and Cr(NO3)3 as Cu2+ and Cr3+ ion source, respectively, using the microcrustacean Daphnia similis. The mean EC50-48h for CuO NPs was 0.064 mg L-1 and for CuSO4 was 0.015 mg L-1. CuO NPs tend to agglomerate, which may have reduced the release of Cu2+ in the test medium in relation to CuSO4.The mean EC50-48h for Cr2O3 NPs was 6.74 mg L-1 and for Cr(NO3)3 was 11.98 mg L-1. The reduced size of the Cr2O3 NPs (15-30 nm) and the higher zeta potential may have contributed to the higher stability in suspension and less potential for agglomeration, partially explaining the higher toxicity of NPs in relation to Cr(NO3)3. After the tests, we observed morphological damages such as increase in fat droplets, internal organ exposure and partially disintegration in organisms exposed to all tested substances, NPs or the salts.

Use of metal-tagged environmentally representative micro- and nanoplastic particles to investigate transport and retention through porous media using single particle ICP-MS

Microplastics and nanoplastics (collectively, MNPs) are increasingly entering soils, with potential adverse impacts to agriculture and groundwater. Environmental detection, characterization, and quantification of MNPs is difficult and subject to artifacts, often requiring labor-intensive separation from environmental matrices. These analytical challenges make it difficult to conduct experiments investigating specific MNP characteristics influencing their transport and fate, particularly when examining multiple plastic types at low concentrations. By synthesizing a suite of metal-tagged polymers, which are cryomilled to create polydisperse fragmented particle suspensions, single particle ICP-MS (spICP-MS) can be used to quantify MNP particle size and concentration in controlled fate and transport studies. Use of unique metal-polymer pairs enables accurate, simultaneous analysis of multiple MNP types which can be used to track total particle transport and retention within a variety of environmental matrices. This was demonstrated using saturated sand column transport experiments to quantify the movement of two plastics having different properties: tin-tagged polystyrene (Sn-PS) and tantalum-tagged polyvinylpyrrolidone (Ta-PVP). The behavior of these polydisperse, fragmented MNPs was compared to that of fluorescent, carboxylated monodisperse PS spherical microspheres (Fl-PS). Mobility of all MNP types increased with decreasing particle size, and hydrophilic Ta-PVP particles migrated more effectively than the hydrophobic Sn-PS particles. Furthermore, the addition of humic acid (HA) to the carrier solution increased the colloidal stability of both metal-tagged MNP suspensions, resulting in much greater elution from the column than in HA-free deionized water or moderately- hard water (ionic strength = 5mM). This combination of particle synthesis and spICP-MS analysis provides insights into the transport of MNP having physical properties that are representative of environmental MNPs and opens up a broad range of applications for study of MNP environmental fate and transport.

Stability of bentonite colloid carried with kaolin-supported nanoscale zero-valent iron together as composite remediation materials and its adsorption property onto multi-heavy metals

In order to improve the defects of fast sedimentation rate and poor mobility of kaolin-supported nano-zero-valent iron (K-nZVI), bentonite colloid with strong suspension and adsorption was selected as the carrier in this study, and the stability and adsorption of bentonite colloid carried with K-nZVI (B-K-nZVI) were studied. The sedimentation tests as well as viscosity tests were prepared to determine the best solid mass ratio of the stable suspension fluid. The adsorption tests combined with adsorption kinetics and isotherm models were conducted to reveal the adsorption and reduction properties of B-K-nZVI to remove chromium, zinc and lead ions. The results showed that B-K-nZVI greatly presented superior stability and determined 5 % of bentonite and 0.2 % of K-nZVI as the best solid mass ratio. The removal rate of Pb and Zn exceeded 90 % within 30 minutes; meanwhile, the removal efficiency was Pb(II) > Zn(II) > Cr(total), indicating that the effect of B-K-nZVI on cations was significantly better than that on anions. In addition, the adsorption capacity of Pb(II), Zn(II) and Cr(total) by B-K-nZVI were 19.11 mg·g−1, 17.33 mg·g−1 and 1.03 mg·g−1 after 30 minutes of reaction, respectively. Compared to K-nZVI, the new composite remediation material has achieved significant improvements in stability and adsorption performance. This study has great significance for demonstrating B-K-nZVI as potential remediation materials to reduce the levels of some heavy metals in groundwater and providing reliable theoretical basis for remediation material design.

INVESTIGATION OF ADSORPTION OF BENTONITE SAMPLES WITH IONOGENIC OLIGOMER BY PHYSICO-CHEMICAL METHODS

The adsorption process of natural and modified Co+2-, Ni+2-bentonite samples taken from Dash-Salahli field with ionogenic oligomer modifiers was carried out and studied by x-ray and infrared spectral analysis methods. Important components that ensure the stability of bentonite suspensions are polymers, ions and surfactants. The main goal of the work is to obtain an organic mineral sorbent using an ionogenic oligomer modifier to stabilize polymer-dispersed systems. The most suitable surfactants are substances with a hydrophilic and hydrophobic statistical distribution in the molecule. The prepared sorbent has both cationic and anionic properties and can adsorb various harmful organic substances. As a result of the research, certain changes were observed in the structure of the sorbents. Depending on the ionic radii of substituted metal ions in natural bentonite, weak, medium. strong intensities are observed

Aminated nanocellulose-mediated synthesis of polyaniline/nanocellulose hybrid materials for sustainable conductive and supercapacitors nanopapers

Diamine-functionalized cellulose nanocrystals (DamCNCs) prepared by periodate oxidation and reductive amination were used as a scaffold for the in-situ oxidative polymerization of polyaniline (PANI). Unlike unmodified CNCs, the hybrid PANI/DamCNC particles formed a stable colloidal suspension over a large pH domain, PANI particles having nucleated and grown from the nanocrystals. The hybridization of PANI was validated by transmission electron microscopy images, along with Fourier-transform infrared, Raman, and UV–Vis spectra. By taking advantage of the colloidal stability of the PANI/DamCNC nanohybrids, flexible and freestanding thin nanopapers were prepared, with different contents in PANI/DamCNCs, using cationic or anionic cellulose nanofibrils (CCNFs or ACNFs, respectively). Conductive nanopapers were obtained by mixing CCNFs with PANI/DamCNCs at a content higher than 20 wt%, exhibiting high flexibility, mechanical integrity, transparency, and stability over time. This work proposes a simple process to fabricate a novel class of biobased conductive hybrid nanofiller based on PANI grafted on DamCNCs, stable in water, that may be used as an additive in nanocellulose suspensions to produce green flexible thin nanopapers, with potential use in different types of electronic devices such as electronic displays, smart packaging, or paper-based supercapacitors for energy storage.

Fuzzy sliding mode control of automotive semi-active suspension based on optimization convergence law

Vehicle suspension smoothness and stability are important indicators for evaluating vehicles. This paper firstly establishes a 1/4 automobile semi-active suspension model, which is used as a reference model for comparison by optimizing the canopy model, and secondly designs the sliding mode controller, including the tracking model error design and the control system design, and then incorporates the optimized saturation function convergence law to control the convergence speed, and then combines it with the fuzzy control to improve the accuracy and robustness of the control system. The optimized semi-active suspension control system will enhance the vehicle’s vibration, smoothness, and stability. The final simulation test results show that the optimized sliding mode control suspension body vertical acceleration is reduced by 26.9%, suspension dynamic deflection by 36.7%, and tire dynamic load dynamic load is reduced by 28.4%.

Enhancing the MRI contrast and hyperthermic properties of magnetic nanoflowers by modulating magnetisation dynamics using poly(butyl cyanoacrylate) shells: Towards multi-functional clinical carriers

Magnetic-polymeric complexes have strong potential as theranostic tools; when prepared as stable suspensions in the nano-range they are functionalisable carriers which can provide MRI (magnetic resonance imaging) tracking, static-field targeting and localised hyperthermia (on AC-field irradiation). In this work the effect of the polymer layer thickness on the MRI and hyperthermic efficacies, in clinically relevant ranges, for poly(butyl cyanoacrylate) encapsulated multi-domain γ-Fe2O3 nanoparticles was investigated for the first time. A series of nanocomposites were prepared at varying particle/polymer ratios revealing that progressively thicker polymer shells maximised the carrier potential and improved the MRI and hyperthermic efficacy due to enhancement of the Néel and partial suppression of the Brownian contribution to the dynamics of the magnetic moments. The implications for the development of multifunctional theranostic agents with optimised efficacy for AC-field triggered release are discussed.

Generation of stable suspension producer cell lines for serum-free lentivirus production.

The production of lentiviral vectors (LVs) pseudotyped with the vesicular stomatitis virus envelope glycoprotein (VSV-G) is limited by the associated cytotoxicity of the envelope and by the production methods used, such as transient transfection of adherent cell lines. In this study, we established stable suspension producer cell lines for scalable and serum-free LV production derived from two stable, inducible packaging cell lines, named GPRG and GPRTG. The established polyclonal producer cell lines produce self-inactivating (SIN) LVs carrying a WAS-T2A-GFP construct at an average infectious titer of up to4.64×107TU mL-1in a semi-perfusion process in a shake flask and can be generated in less than two months. The derived monoclonal cell lines are functionally stable in continuous culture and produce an average infectious titer of up to 9.38×107TU mL-1in a semi-perfusion shake flask process. The producer clones are able to maintain a productivity of>1×107TUmL-1day-1for up to 29 consecutive days in a non-optimized 5L stirred-tank bioreactor perfusion process, representing a major milestone in the field of LV manufacturing. As the producer cell lines are based on an inducible Tet-off expression system, the established process allows LV production in the absence of inducers such as antibiotics. The purified LVs efficiently transduce human CD34+ cells, reducing the LV quantities required for gene and cell therapy applications.

Synthesis, Characterization and Thermal Studies of Composite Nanofluids and their Comparison with Hybrid Nanofluids

Ternary nanofluids can either be an admixture of three distinct nanoparticles or the dispersion of a ternary nanocomposite in a base fluid. This work focuses on the synthesis, morphological characterization, stability analysis, estimation and optimization of thermophysical parameters of ternary nanofluids consisting of multiwalled carbon nanotubes, graphene oxide and silver (CNT-GO-Ag). Two cases are considered and compared viz. (i) hybrid nanofluids (HNF) prepared from monofluids and (ii) composite nanofluids (CNF) prepared by the dispersion of ternary nanocomposites. The CNF was found to have an enhanced thermal conductivity ratio (knf/kb) of 40% as compared to 30% for HNF at 30 ºC. This enhancement for the CNF and HNF were found to be 45% and 32%, respectively at the electronic cooling exposure temperature of ~40 to 50 ºC. The zeta potential analysis also proved that CNF had superior suspension stability than HNF. The viscosity of CNF was found to be 8% (at 20 ºC) to 20% (at 80 ºC) lower than HNF, much desired for fluid flow characteristics. Overall, the results show that CNF as compared to HNF possesses superior thermophysical properties with good potential for application in electronic cooling studies.

The suspension stability of nanoplastics in aquatic environments revealed using meta-analysis and machine learning

Nanoplastics (NPs) aggregation determines their bioavailability and risks in natural aquatic environments, which is driven by multiple environmental and polymer factors. The back propagation artificial neural network (BP-ANN) model in machine learning (R2 = 0.814) can fit the complex NPs aggregation, and the feature importance was in the order of surface charge of NPs > dissolved organic matter (DOM) > functional group of NPs > ionic strength and pH > concentration of NPs. Meta-analysis results specified low surface charge (0 ≤ |ζ| < 10 mV) of NPs, low concentration (< 1 mg/L) and low molecular weight (< 10 kg/mol) of DOM, NPs with amino groups, high ionic strength (IS > 700 mM) and acidic solution, and high concentration (≥ 20 mg/L) of NPs with smaller size (< 100 nm) contribute to NPs aggregation, which is consistent with the prediction in machine learning. Feature interaction synergistically (e.g., DOM and pH) or antagonistically (e.g., DOM and cation potential) changed NPs aggregation. Therefore, NPs were predicted to aggregate in the dry period and estuary of Poyang Lake. Research on aggregation of NPs with different particle size,shapes, and functional groups, heteroaggregation of NPs with coexisting particles and aging effects should be strengthened in the future. This study supports better assessments of the NPs fate and risks in environments.

Cyrene- and water-based exfoliation of black phosphorus for potential nanolayer-mediated disaggregation of insulin fibrils

Liquid suspensions of phosphorene nanolayers (2D-bP) obtained through liquid phase exfoliation (LPE) of elemental black phosphorus (bP) have been prepared and extensively characterized. The exfoliating ability of deionized water (DI water), dihydrolevoglucosenone, (Cyrene), and N-methyl-2-pyrrolidone (NMP) has been investigated and compared along with the differences in the structure, concentration, and stability of the collected nanoflakes. Water was chosen as an exfoliating medium due to its harmlessness and cost-effectiveness and because it is the safest solvent for further potential biomedical applications. Cyrene is a new bio-based solvent still under study. NMP, which is among the most widely used solvents for the exfoliation of 2D systems including bP, has been employed for comparison. The obtained suspensions have been characterized by Dynamic Light Scattering (DLS), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Phosphorus 31 Nuclear Magnetic Resonance (31P NMR), Transmission Electron Microscopy (TEM), Ultraviolet -Visible (UV–Vis), and Raman spectroscopies. The stability of 2D-bP suspensions over time and their photoactivity, i.e., their ability to generate singlet oxygen species as a photosensitizer, have been investigated. The collected results evidenced that the exfoliation of bP in different solvents, including DI water, resulted in satisfactory and comparable nanoflake structures and features. The singlet oxygen generation through irradiation of 2D-bP in DI water suspensions, advantageously obtained directly from LPE, showed promising potential for use in photodynamic therapy (PDT). Preliminary data on the potential biomedical application of 2D-bP to inhibit the insulin self-assembly into amyloid aggregates as well as to cause fibrils disassembling through simple incubation or photoactivity, are also discussed.

Mucoadhesion, Rheology, Swelling Behavior, and Immunomodulatory Properties of Polysaccharides of Gum Exudates Obtained from Astracantha echidnaeformis (Sirj.) Podlech as a Formulary Excipient Candidate

AbstractThe physicochemical, rheological, and mucoadhesive characteristics of gum derived from Astracantha echidnaeformis are investigated. It's polysaccharides are isolated using chromatography techniques, and their immunomodulatory characteristics are evaluated by subjecting Jurkat cells to the WST‐1 assay. The composition of these polysaccharides is analyzed using gas chromatography‐mass spectrometry (GC‐MS). The viscosity and shear‐thinning behavior of gum are directly influenced by its concentration and the presence of NaCl, whereas they are inversely affected by temperature. The gum has strong potential as a thickening agent for dispersed systems. The mucoadhesion strength of the gum insoluble fraction is 109 ± 4.58 g cm−2, indicating excellent adhesiveness for application to mucoadhesive formulations. Cells’ proliferation enhancement is found for the isolated manno‐arabinoglucan (MW: ≤1.27 kDa) and galacto‐arabinan (MW: ≥667.8 kDa) at concentrations lower than 400 µ mL−1, but at higher concentrations they inhibited the proliferation. The isolated pectic galacto‐arabinan (MW: 669.58 kDa) exhibited a proliferative effect at 250 µg mL−1, but the isolated manno‐galactoglucan (MW: 80.90 kDa) showed cytotoxicity at higher doses. The isolated proteoglycans has mostly galacto‐arabinan backbones with immunomodulatory properties. The gum can be used as a thickening agent for the physical stabilization of suspensions and gels, specifically those needing to be stored at cold temperatures.

Effects of Ultrasonic Treatment on Physical Stability of Lily Juice: Rheological Behavior, Particle Size, and Microstructure.

The aim of this study was to investigate the rheological properties, particle size distribution, color change, and stability of lily juice under different ultrasonic treatment conditions (152 W, 304 W, 456 W, 608 W, and 760 W). The results showed that the lily juice exhibited non-Newtonian shear thinning behavior, and the viscosity decreased with the increase in ultrasonic power. Under ultrasonic treatment conditions, there was no significant change in the pH value and zeta potential value of the samples. The content of cloudy value and total soluble solids (TSS) increased gradually. However, both the sedimentation components and centrifugal sedimentation rate showed a downward trend and an asymptotic behavior. In addition, high-power ultrasound changed the color index (L* value decreased, a* value increased), tissue structure, and particle distribution of the sample, and small particles increased significantly. To sum up, ultrasonic treatment has great potential in improving the physical properties and suspension stability of lily juice.

Aggregation-Induced Emission of Naphthalene Diimides: Effect of Chain Length on Liquid and Solid-Phase Emissive Properties.

The aggregation-induced emission (AIE) properties of a systematic series of naphthalene diimides (NDIs) varying the chain length at the imide positions have been studied. A solvophobic collapse of NDI units through the flash injection of THF NDI solutions in sonicating water triggers the formation of stable suspensions with enhanced fluorescence emissions. Shorter chains favor the π-π stacking of NDI units through H-aggregation producing a strong AIE effect showing remarkably high quantum yields that have not been observed for non core-substitued NDIs previously. On the other hand, NDIs functionalized with longer chains lead to more disordered domains where π-π stacking between NDI units is mainly given by J-aggregation unfavoring the AIE effect.

Novel surface modification strategies for enhanced CeO2 nanoparticle dispersion and suspension stability

This work aims to modify the surface characteristics of cerium oxide (ceria, CeO2) nanoparticles using different surface modification strategies for improved CeO2 nanoparticle dispersion and suspension stability. Analysis and discussion were conducted on the two surface modification processes used by a cationic surfactant like hexadecyl cetyltrimethylammonium bromide (CTAB) and a silane agent like tetraethyl orthosilicate (TEOS). Untreated CeO2 was used as reference material. The dispersion effect of surface-modified CeO2 nanoparticles at different pHs was determined by zeta potential measurements. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Particle size analysis (PSA), Thermogravimetric analysis (TGA), Scanning electron microscope (SEM), Brunauer–Emmett–Teller analysis (BET), and X-ray diffraction (XRD) were used to confirm the efficacy of the surface modification of CeO2 nanoparticles. First, the results obtained in this experimental work demonstrate that both advanced modifications greatly enhance the dispersion and suspension stability of surface-modified CeO2 nanoparticles in comparison with untreated CeO2 nanoparticles. Second, it is also shown that the surface-modified CeO2 nanoparticles obtained through a silanization surface process with TEOS silane agent had a better dispersion effect and dispersion stability than the surface-modified CeO2 nanoparticles obtained by surface modification with CTAB cationic surfactant. These results can help better understand how advanced surface modifications can assist the application of well-dispersed CeO2 nanoparticles in technological applications.