Particles In Solution Research Articles

Development of a stable and efficient zein based nanopesticides through green and simple way for improving utilization efficiency

• Self-assembly of water-soluble zein peptides to form pesticide-loaded nanoparticles. • Nanoparticles exhibit excellent stability and redispersibility. • The slow-release nanoformulation maintains the insecticidal activity. • Nanoencapsulation protects avermectin from UV light. Nanopesticides represent one of the effective ways of reducing the use of pesticides and the environmental pollution. Natural zein as a potential carrier for nanoencapsulation of pesticides has the disadvantages of large amount of organic solvents and poor dispersibility. In this study, a water soluble of zein peptides was obtained by hydrolyzed under alkaline conditions with heated and stability of nanopesticides were prepared through crosslinked after self-assemble. As the results, the zein peptides spontaneously assembled into spherical particles in an aqueous solution, the nanopesticides (avermectin, AVM), with uniform size distribution and size can be adjusted by the glutaraldehyde, have a great stability, and redispersed in water after freeze-drying. Moreover, nanoencapsulation protects avermectin from UV light, with 24% of the encapsulated AVM remaining intact after exposure to UV for 60 min, compared to less than 6% for the bare AVM. In addition, the nanoformulation had similar insecticidal activity to commercial EC and the cross-linking of particles slowed down the release rate and the curves were consistent with Higuchi model different from the abnormal diffusion in the uncross linked state. In short, this study provides a simple method to obtain stabilizable nanopesticides based on natural polymer on a green way.

Characterisation, hardness and corrosion behaviour of electrodeposited ZnFe and ZnFe/BN composite coatings

ABSTRACT ZnFe and ZnFe/BN composite coatings were successfully electrodeposited on 304 stainless steel substrates by pulse electrodeposition technique. The effect of various concentrations of BN particles in the plating solution on the structural, hardness and corrosion properties of electrodeposited ZnFe alloy and ZnFe/BN composites were investigated. The deposition process and electrochemical behaviour of alloy and composite coatings were analysed by the Cyclic Voltammetry (CV) method. X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used for the structural, and morphological characterisation of the coatings. Vickers micro hardness indentation was used to determine the hardness of the deposits. The corrosion behaviour of ZnFe alloy and ZnFe/BN composites was investigated by open circuit potential (OCP), Tafel plots, and electrochemical impedance spectroscopy (EIS) methods. As the BN particle content in ZnFe/BN composite coatings rose, the microhardness, and corrosion resistance of coatings increased, which was due to the function of grain refinement and changing dispersion strengthening. Meanwhile, grain sizes were strongly affected from the presence of BN particles and their content. The ZnFe/BN composite coatings with the BN particle concentration of 20 g L−1 had the highest corrosion resistance, and microhardness.

High-Temperature Wear Behavior of CoCr Matrix Coatings Reinforced by Niobium Element From Room Temperature to 1000 °C

Abstract The high-temperature wear resistant CoCr matrix coatings reinforced by the Nb element were fabricated on the Inconel 718 alloy by using the hot-pressed sintered method. The effects of Nb on the microstructure, hardness, and high-temperature tribological performance of coatings are also investigated in detail, and Nb content was further optimized. The tribological properties were investigated by using a ball-on-disk tribo-tester at 23 °C (room temperature), 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. The results showed that the Nb element showed the solution strengthening effect and particle strengthening effect. The Nb greatly affected the tribological performance of the coatings. With the increase of Nb content, the wear-rate and friction coefficient initially decreased and then increased. There was a critical value of Nb content for the high-temperature wear behavior of coatings. The coating with 5.0 wt% Nb kept the best tribological properties compared with other specimens, and the wear resistance was 1.4–29 times as high as that of the substrate. It was attributed to the high hardness, high load-bearing capacity of the Nb-rich phases, and oxide lubricating film on the worn surfaces. The corresponding wear mechanism was discussed.

Selective Laser Melted Rare Earth Magnesium Alloy with High Corrosion Resistance.

Magnesium (Mg) degrades too fast in human body, which limits its orthopedic application. Single-phase Mg-based supersaturated solid solution is expected to possess high corrosion resistance. In this work, rare earth scandium (Sc) was used as alloying element to prepare Mg(Sc) solid solution powder by mechanical alloying (MA) and then shaped into implant using selective laser melting (SLM). MA utilizes powerful mechanical force to introduce numerous lattice defects, which promotes the dissolution of Sc in Mg matrix and forms supersaturated solid solution particles. Subsequently, SLM with fast heating and cooling rate maintains the original supersaturated solid solution structure. Immersion tests revealed that high Sc content significantly enhanced the corrosion resistance of Mg matrix because of the formation of protective corrosion product film, which was also proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg(Sc) alloy showed a relatively low degradation rate of 0.61 mm/year. In addition, cell tests showed that the Mg(Sc) exhibited favorable biocompatibility and was suitable for medical application.

Hollow fiber membranes with knitted braid-like structures for process intensification via generation of Dean vortices

ABSTRACT A novel module of hollow fiber membranes with knitted braid-like structures has been successfully developed for process intensification via generation of Dean vortices. In the curved channels of hollow fiber membranes with three-fiber knitted braid-like structures, Dean vortices are effectively generated if the feed flowrates are higher than the critical flowrate. With proper structural parameters and feed flowrates, Dean vortices generated in hollow fiber membranes with three-fiber knitted braid-like structures effectively suppress the membrane fouling caused by fine particles in feed solutions no matter how the shape, size and concentration of particles vary; as a result, the transmembrane water fluxes of hollow fiber membranes with three-fiber knitted braid-like structures are evidently higher than those of straight hollow fiber membranes under the same operation conditions. The increase ratio of transmembrane water flux of hollow fiber membranes with three-fiber knitted braid-like structures increases with increasing the feed flowrate or increasing the particle concentration. The hollow fiber membranes with three-fiber knitted braid-like structures exhibit good long-term anti-fouling performances. The proposed strategy and findings in this study provide valuable guidance for developing efficient modules for hollow fiber membranes to achieve process intensification with low energy consumption, which are highly promising for industrial applications.

High strength and high electrical conductivity C70250 copper alloy with fibrous structure reinforced by high density, multi-scale nano-precipitates and dislocation

Cu–Ni–Si alloy has a difficult combination of high strength and high electrical conductivity, which limits its further application in electronics industry. In this work, the effects of large deformation double cold rolling-aging processes on the microstructure, mechanical properties and electrical conductivity of the columnar grain alloy were studied, and its mechanism was revealed. The results show that the C70250 copper alloy strip prepared by hot mold continuous casting technology can be directly subjected to large deformation double cold rolling-aging treatments without solid solution process. The excellent balance of tensile strength and electrical conductivity, as high as 884 MPa and 45.7% IACS, respectively, can be obtained for the alloy after primary 95% cold rolling and aging at 450 °C for 45 min followed by secondary 60% cold rolling and aging at 400 °C for 10 min. The strength and electrical conductivity is better than the similar products reported. The realization of high strength and high electrical conductivity is attributed to the interaction between strain hardening and precipitation behavior of columnar alloy during double deformation and aging treatment. The repeated introduction of large deformation cold rolling provides a new short diffusion driving force for the precipitation of solute atoms by GPA and APT results, the precipitation rate is increased in the second stage of aging. At the same time, the nanometer-sized strengthening phase formed by primary aging can effectively nail the dislocations formed in the secondary cold rolling process, and finally form a fibrous structure with uniform mixing of multi-scale nano cluster and Ni2Si phase. The strength of the alloy is significantly improved by dislocation strengthening and multi-scale precipitation strengthening. C70250 copper alloy precipitate as many solute atoms as possible, and retains fibrous structure, the dispersing of electrons by solute particles and grain boundary limits is fundamentally diminished, and the electrical conductivity is improved.

Modification in Silver Staining Procedure for Enhanced Protein Staining.

Silver staining is an excellent technique for detecting proteins that are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Protein silver staining technology has higher sensitivity and is suitable for the detection of low-concentration proteins compared to other staining techniques including the Coomassie brilliant blue detection method. The present study was conducted to enhance the detection ability of the protein staining method. Herein, we modified the recipe of silver staining, a very reproducible method, by adding AMP, PVP, Tween-80, and xylene to enhance the detection ability of protein staining. Furthermore, the particle size and potentiometer were used to detect the particle size and potential difference of the silver ions in the prepared dyeing materials, and then, the morphology, transparency, and size of the dyed silver particles in different dyeing solutions were studied using a transmission electron microscopy (TEM). The obtained results revealed that the use of 0.5% of AMP, PVP, Tween-80, and xylene improved the staining ability of protein silver staining, compared with the original method. Furthermore, 0.5% AMP, 0.5% PVP, 0.5% Tween-80 reagents significantly influenced the morphology, size, potential, and dispersion of silver ions. These results suggested a new idea for further improving the detection ability of protein silver staining.

Metal-ion inserted vanadium oxide nanoribbons as high-performance cathodes for aqueous zinc-ion batteries

The current energy and environmental crises are driving the burgeoning demand for efficient and reliable energy storage devices. Aqueous zinc-ion batteries (ZIBs) are currently considered to be promising candidates because of their excellent safety in operation and low cost. However, the real-world application of ZIBs has been impeded by a lack of cost effective cathode materials with the requisite high capacities and stability. Here we report the preparation and relevant properties of a special class of layered materials, which can be described as metal ion-inserted vanadium oxide (MVO, M = Zn, K, Na, and Ca) nanoribbons, as cathode materials for ZIBs. Metal ions are inserted into vanadium oxide by mixing the respective metal chloride with V2O5 particles in aqueous solution at room temperature, resulting in layered MVOs with expanded interlayer spaces. When used as the cathode material for ZIBs, ZnVO nanoribbons delivered specific capacities of 414.8, 368.6, 318.2, 271.2, 225.8 and 163.5 mAh g−1 at current rates of 0.1, 0.2, 0.5, 1, 2 and 5 A g−1, respectively. Also, a capacity of 409.6 mAh g−1 was retained after current rate was returned to 0.1 A g−1. After cycling at 2 A g−1 for 1500 cycles, 84.4% of the initial capacity was retained, much higher than that possible using pristine V2O5. The synthesis strategy can be easily scaled up to a 10-liter reaction scale, demonstrating its potential for the large scale production of cathode materials for high-performance aqueous ZIBs.

Long-Range Ionic and Short-Range Hydration Effects Govern Strongly Anisotropic Clay Nanoparticle Interactions.

The aggregation of clay particles in aqueous solution is a ubiquitous everyday process of broad environmental and technological importance. However, it is poorly understood at the all-important atomistic level since it depends on a complex and dynamic interplay of solvent-mediated electrostatic, hydrogen bonding, and dispersion interactions. With this in mind, we have performed an extensive set of classical molecular dynamics simulations (included enhanced sampling simulations) on the interactions between model kaolinite nanoparticles in pure and salty water. Our simulations reveal highly anisotropic behavior, in which the interaction between the nanoparticles varies from attractive to repulsive depending on the relative orientation of the nanoparticles. Detailed analysis reveals that at large separation (>1.5 nm), this interaction is dominated by electrostatic effects, whereas at smaller separations, the nature of the water hydration structure becomes critical. This study highlights an incredible richness in how clay nanoparticles interact, which should be accounted for in, for example, coarse-grained models of clay nanoparticle aggregation.

Study on the effect of ionic strength on particle migration and deposition in porous media covered by biofilm based on coupled Lattice Boltzmann method and Discrete element method

AbstractBiofilms covering porous media will interact with particles and affect particle migration. In order to investigate the migration mechanism of particles in porous media covered by biofilms, the migration process of particles with different particle sizes under the condition of the changing ionic strength is analyzed by using the lattice Boltzmann method–discrete element method (LBM‐DEM) coupling method from mesoscopic scale. The variation patterns of ion strength include gradient and mutation, respectively. Also, the agglomeration of particles at the pore throat in porous media is investigated under different conditions. The main results are obtained as follows. First, both the change of ionic strength and its changing mode significantly affect the migration behavior of particles in NaCl solution but have little effect on the behavior of particles in CaCl2 solution. Second, when the pressure difference between the pressure difference between the inlet and outlet of porous media is 0.4 kPa, the residual permeability of 1.5‐μm particles in the NaCl solution with ionic strength mutation is the highest, which has value of 64.92%. Third, at the specific flow rate, the particles in low ionic strength solution are more likely to be settled. The attraction of particles in the CaCl2 solution is one order of magnitude less than that in the NaCl solution, and the accumulated particles are more likely to be dispersed.

Resolutions to the Problems Caused by Introducing both Osmolarity and Effective Osmolarity

IntroductionIn the literature, 2 types of osmolarity are introduced: osmolarity (OS, the concentration of the total solute particles (SP) of a solution (S)) and effective osmolarity (EOS, the concentration of the impermeant SP (imp‐SP) in S). Introducing 2 types of osmolarity causes 3 problems in dealing with osmosis. In this presentation, we address these problems and resolve them.MethodLogical reasoning.Results1) Addressing the 3 problemsi. The fact that both OS and EOS are introduced in the literature is one of the four causes of inconsistency in the definitions of tonicity addressed in our first abstract1 to EB2022.ii. The fact causes a great confusion between the meanings of the following terms: hyper‐osmotic or iso‐osmotic or hypo‐osmotic (referred to as x‐osmotic) vs. hypertonic or isotonic or hypotonic (x‐tonic). Some literature specifies that x‐osmotic is used to compare 2 OS and x‐tonic to compare 2 EOS. Consequently, x‐osmotic and x‐tonic compare two different properties (apples and oranges) and knowing one relationship does not mean we know the other, e.g., “iso‐osmotic is not always isotonic”2. Moreover, if S1 (with an OS of 600 mOsm/L) is hyper‐osmotic to S2 (its OS = EOS = 300 mOsm/L), S1 can be hypertonic or isotonic or hypotonic to S2 if it contains 200 mM permeant SP (p‐SP) + 400 mM impermeant SP (imp‐SP), or 300 mM p‐SP + 300 mM imp‐SP, or 400 mM p‐SP + 200 mM imp‐SP, respectively.iii. It is unclear what real osmolarity is.2) The resolutionsi. As illustrated previously3, real osmolarity is the osmotic concentration (OC, the concentration of the imp‐SP, a variable during osmosis in a simple osmosis system (S‐m‐H2O) where m refers to a semipermeable membrane separating S and H2O compartments); OC0is the initial OC before osmosis occurs (time = 0) and of practical use. OC0 is membrane (m)‐dependent: Facing different m, the resulting fraction of the imp‐SP in S‐m‐H2O is different. Hence, real osmolarity is neither OS nor EOS: OS contains permeant SP that do not exert an osmotic pressure; OS is a misconception of the term CTSP (the molar concentration of the total SP in S that is inherent to S and m‐independent)3. It is unclear whether EOS is a variable or a constant. OC0 is a system parameter owned by a simple osmosis system (S‐m‐H2O), whereas OS and EOS are owned by a solution.ii. If OS is replaced by CTSP and EOS is replaced by OC0, then all problems addressed in this and our first abstracts to EB2022 are eliminated and x‐osmotic has the same meaning as x‐tonic, so that if S1 is x‐osmotic to S2, it is also x‐tonic to S2. See our third EB2022 abstract titled Origin of the Term “Isotonic”.ConclusionsBy applying CTSP to replace OS and OC0 to replace EOS, we have proved the effectiveness of CTSP and OC0 in eliminating the problems presented in this and our first abstracts1.

Unification of the Multiple Forms of van 't Hoff’s Law into One General Form

IntroductionThe first Nobel Prize in Chemistry was awarded to Jacobus Henricus van 't Hoff in 1901 for his discoveries of the laws of chemical dynamics and osmotic pressure (π) in solutions. The original form of van 't Hoff’s law illustrates the relationship between π and the molar concentration (C) of a solution (S) facing a membrane (m) that separates the S and water compartments and is only permeable to water: π = C·RT, where R is the gas constant and T is the absolute temperature. However, in reality, both biological and artificial membranes can be extremely complex, so that facing different m, the resulting fractions of the impermeant solute particles (imp‐SP) contributing to πis different. The composition of the total solute particles (TSP that includes imp‐SP and permeant SP (p‐SP)) in S and their interactions may also be complex. For these reasons, multiple forms of van 't Hoff’s law have been developed over time to adapt to the different levels of complexity of solutions and/or membranes. In our previous works, we have done the following: 1) Defined the osmosis setting above as a simple osmosis system (S‐m‐H2O) and the setting of S1‐m‐S2 as a composite osmosis system that can be deconstructed into two mirrored simple osmosis systems: S1‐m‐H2O and H2O‐m‐S21, 2. 2) Addressed the many problems in the current definitions of osmolarity (osmotic concentration, OC) and tonicity1‐6. 3) Reasoned out what real osmolarity is: the osmotic concentration (OC, the concentration of the imp‐SP resulting from the interaction between the composition of S and m) in S‐m‐H2O1. OC in boldface is differentiated from OC in regular face. OC is a m‐dependent variable during osmosis whose initial value before osmosis occurs (i.e,, time = 0) is OC0, a constant of practical use. 4) Proved the correctness and effectiveness of OC0 in eliminating all the problems we addressed with the current definitions of osmolarity and tonicity1‐6. Moreover, by applying OC0 to van 't Hoff’s law, the multiple forms of the law can be unified into one general form. This presentation demonstrates 1) how this unification occurs; 2) how the unified form can be applied to a composite S1‐m‐S2.MethodLogical reasoningResults1. Multiple forms ofvan 't law and their unificationTable 1 shows the unification of the multiple forms of the law into one general form: π = OC0·RT.2. Applying the unified form ofvan 'tHoff’s law to a composite osmosis system (S1‐m‐S2)Figure. 1 illustrates the application of the unified form of the law in S1‐m‐S2: ∆π = ∆OC0·RT.ConclusionsThe unification of the multiple forms of van 't Hoff’s law using OC0 into a general form (π = OC0·RT) is a significant theoretical development of the law. The original form of the law is a special case of the general form.

Synthesis and electrochemical performance of V2O5 nanosheets for supercapacitor

Electrode materials are the key to the electrochemical performance of supercapacitors. This study reports the electrochemical properties of V2O5 supercapacitors. V2O5 nanosheets with different morphologies were prepared by controlling the solvent under a facile hydrothermal method. The phase and the morphology of the samples were characterized by x-ray diffraction and scanning electron microscopy. The electrochemical properties of V2O5 nanosheets with different morphologies were studied by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The charge transfers resistance decreases from 3.2 Ω of V2O5 particles to 2.0 Ω of V2O5 nanosheets. V2O5 nanosheets exhibit higher specific capacity (375 F g−1) than V2O5 particles (318 F g−1) in K2SO4 solution. The cycling capacity retention keeps 96.8% for 1000 cycles at 0.5 A g−1 in K2SO4 solution, indicating better cycling stability.

A Resolution for the Inconsistency in the Definitions of Tonicity

IntroductionThere is great inconsistency in the current definitions of tonicity, which hinders research, teaching, and learning about osmosis across the cell membrane. In this abstract, we 1) show the inconsistency in the literature; 2) reveal what caused it and resolve it.MethodLogical reasoning.Results1) The inconsistencyTable 1 shows a collection of 14 descriptions/definitions of tonicity classified into 5 categories (Cat.), which indicates that the level of the inconsistency is high and the truth of tonicity is elusive.2) Causes and resolution of the inconsistencyAs we illustrated previously1, tonicity should be defined in a composite osmosis system, which can be deconstructed into 2 simple osmosis systems that are mirrored: S1‐m‐S2 = S1‐m‐H2O + H2O‐m‐S2, where S1 and S2 are two solutions separated by a membrane (m) that is only permeable to H2O in this abstract. Lack of this understanding is the first cause.Second, the owner of tonicity is wrongly reflected in the definitions of Cat. 1, 2, and 3 in the Table, phrased as “a solution’s tonicity” or “the tonicity of a solution”. Neither S1 or S2 in S1‐m‐S2owns tonicity because it reflects a comparison of the 2 initial concentrations of the impermeant solute particles in S1‐m‐S2(i.e., OC0(S1) and OC0(S2), where OC0 refers to osmotic concentration before osmosis occurs, i.e., time = 01, 2. As in a game that has two players, the result of the game (a qualitative statement of “player 1 won the game” or “player 2 lost the game” or a quantitative score of 12 to 9) reflects a comparison of the points (strengths) of the 2 players, so the game system owns the result. Osmosis in S1‐m‐S2 is like a water‐competing game between OC0(S1) and OC0(S2). Tonicity expressed qualitatively as “S1 is hypertonic to S2” or quantitatively as “300 : 200” if OC0(S1) = 300 mOsm/L and OC0(S2) = 200 mOsm/L, reflects a comparison of the osmotic strengths of OC0(S1) and OC0(S2), thus predicts the result of osmosis, i.e., a change in cell volume1. Hence, it is the composite S1‐m‐S2 system that owns tonicity (the comparison or prediction or the result of osmosis). “A solution’s tonicity” makes it impossible to define tonicity. Knowing the truth of tonicity, the definitions in Cat. 3 fail to define what tonicity is and reflect the result of osmosis inappropriately. The definitions in Cat. 5 obviously make no sense.The 3rd and 4th causes are addressed and resolved in our 2nd and 3rd abstracts titled Resolutions to the Problems of Introducing both Osmolarity and Effective Osmolarity and Origin of the Term “Isotonic”, respectively.ConclusionsTonicity can be expressed in multiple ways. The definitions in Cat. 4 express tonicity appropriately as something relational between S1 and S2 if OC0is the focus, not osmolarity or effective osmolarity. The last definition in Cat. 4 is accurate among all 14 definitions, with which, the result of osmosis (i.e., the osmotic pressure gradient after osmosis)3 is used to express tonicity.

Origin of the Term “Isotonic”

IntroductionIn our 1st and 2nd abstracts to EB2022, we addressed the inconsistency in the definitions of tonicity1 and the problems of introducing both osmolarity and effective osmolarity2 and resolved these issues. In this abstract, we introduce the origin of the term “isotonic”, which further clarifies the confusion about tonicity and leads to an understanding of the membrane (m)‐dependency of tonicity, one of the 3 properties of tonicity3.MethodLogical reasoning.Results1) The term “isotonic” was coined by the botanist Hugo de Vries in the 19th century4. In his experimental setup, if S1 caused a certain degree of shrinkage of a cell and S2 caused the same degree of shrinkage of the same cell, then S1 and S2 were considered “isotonic solutions” because they have an equal “water attracting force”. We now know that it is the impermeant solute particles (imp‐SP) in S1 and S2 that pull water to their compartments in the osmosis systems S1‐m‐S3 and S2‐m‐S3, respectively, where S3 refers to the intracellular fluid (ICF) of the cell. That time, De Vries seemed not to be aware that when his S1 is isotonic to S2, S1 and S2 are both hypertonic to S3, or vice versa, S3 is hypotonic to S1 and S2.2) The term “x‐tonic (i.e., hypertonic or isotonic or hypotonic)” compares the 2 water attracting forces in an osmosis system, such as S1‐m‐S3 or S2‐m‐S3. Obviously, it is the imp‐SP that exert this “water attracting force” (more appropriately this “pressure”). If we call this pressure “the osmotic tone” (i.e., the osmotic energy or strength), then the meaning of the term “x‐tonic” is clear: It compares the 2 osmotic tones in an osmosis system such as S1‐m‐S2. Lack of an understanding of this point leads to the following illogical descriptions about tonicity: a common saying “S1 is isotonic to the cell” compares an apple with an orange and another common saying “S1 is isotonic” is not a complete sentence. These illogical statements result from the inconsistency in the definitions of tonicitywe addressed previously1 and increase the level of confusion about what tonicity is, which we have addressed previously1, 3.3) The logic that if a cell swells/shrinks in a solution, the solution is hypotonic/hypertonic to ICF is commonly reflected in the literature, but this reverses the cause and effect: It is because the ICF is hypertonic/hypotonic to the solution, so that the ICF wins/loses the water competing game (i.e., osmosis) across the cell membrane, or in other words, the winner (ICF) gains water and volume (cell swelling)/the loser (ICF) loses water and volume (cell shrinkage).ConclusionsThis abstract and our previous works listed in the References section together eliminate all problems related to the concept of tonicity.

Diffusiophoresis of a moderately charged spherical colloidal particle.

An analytic expression is obtained for the diffusiophoretic mobility of a charged spherical colloidal particle in a symmetrical electrolyte solution. The obtained expression, which is expressed in terms of exponential integrals, is correct to the third order of the particle zeta potential so that it is applicable for colloidal particles with low and moderate zeta potentials at arbitrary values of the electrical double-layer thickness. This is an improvement of the mobility formula derived by Keh and Wei, which is correct to the second order of the particle zeta potential. This correction, which is related to the electrophoresis component of diffusiophoresis, becomes more significant as the difference between the ionic drag coefficients of electrolyte cations and anions becomes larger and vanishes in the limit of thin or thick double layer. A simpler approximate mobility expression is further obtained that does not involve exponential integrals.

Preparation of Biocompatible Poly(2-(methacryloyloxy)ethyl phosphorylcholine) Hollow Particles Using Silica Particles as a Template.

Hydrophilic poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) shows biocompatibility because the pendant phosphorylcholine group has the same chemical structure as the hydrophilic part of phospholipids that form cell membranes. Hollow particles can be used in various fields, such as a carrier in drug delivery systems because they can encapsulate hydrophilic drugs. In this study, vinyl group-decorated silica particles with a radius of 150 nm were covered with cross-linked PMPC based on the graft-through method. The radius of PMPC-coated silica particles increased compared to that of the original silica particles. The PMPC-coated silica particles were immersed in a hydrogen fluoride aqueous solution to remove template silica particles to prepare the hollow particles. The PMPC hollow particles were characterized by dynamic light scattering, infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy observations. The thickness of the hollow particle shell can be controlled by the polymerization solvent quality. When a poor solvent for PMPC was used for the polymerization, PMPC hollow particles with thick shells can be obtained. The PMPC hollow particles can encapsulate hydrophilic guest molecules by immersing the hollow particles in a high-concentration guest molecule solution. The biocompatible PMPC hollow particles can be used in a drug carrier.

Methylparaben as a preservative in the development of a multi-dose HPV-2 vaccine

ABSTRACT The human papillomavirus (HPV) vaccine is the simplest, most economical, convenient, and effective method of preventing cervical cancer. However, the current HPV vaccine is supplied as a single-dose vial with a relatively high cost per dose, which hinders its supply to low- and middle-income countries (LMICs), where the demand for HPV vaccine is highest. Therefore, it is necessary to develop a multi-dose HPV vaccine to promote large-scale affordable vaccination in LMICs. Moreover, the addition of preservatives is required to reduce the risk of microbial contamination in multi-dose vaccines within a single vial. In this study, we investigated the effects of six preservatives on HPV 16L1 and 18L1 virus-like particles in solution, as well as the aluminum adsorption status, under normal and high-temperature conditions. Multiple methods were employed, including dynamic light scattering, differential scanning calorimetry, an in vitro relative potency assay, and an in vivo potency assay in mice. Based on the above results, four types of selected preservatives were further studied, and an antimicrobial effectiveness test was performed on the HPV-2 vaccine, which was employed as a model HPV vaccine. Finally, three preservatives were selected based on their performance to evaluate the long-term stability of the HPV-2 vaccine. The results indicated that 0.12% methylparaben is the most suitable preservative for the multi-dose HPV-2 vaccine, guaranteeing the shelf life for at least three years and meeting “B” standards for antimicrobial effectiveness. The formula developed in this study can contribute toward combating cervical cancer in LMICs.

Sonochemistry of actinides: from ions to nanoparticles and beyond

AbstractSonochemistry studies chemical and physical effects in liquids submitted to power ultrasound. These effects arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species. In principle, each cavitation bubble can be considered as a microreactor initiating chemical reactions at mild conditions. In addition, microjets and shock waves accompanied bubble collapse produce fragmentation, dispersion and erosion of solid surfaces or particles. Microbubbles oscillating in liquids also enable nucleation and precipitation of nanosized actinide compounds with specific morphology. This review focuses on the versatile sonochemical processes with actinide ions and particles in homogenous solutions and heterogenous systems. The redox reactions in aqueous solutions, dissolution or precipitation of refractory solids, synthesis of actinide nanoparticles, and ultrasonically driving decontamination are considered. The guideline for further research is also discussed.

MOF/Polymer Mixed-Matrix Membranes Preparation: Effect of Main Synthesis Parameters on CO2/CH4 Separation Performance.

Design and preparation of mixed-matrix membranes (MMMs) with minimum defects and high performance for desired gas separations is still challenging as it depends on a variety of MMM synthesis parameters. In this study, 6FDA-DAM:DABA based MMMs using MOF-808 as filler were prepared to examine the impact of multiple variables on the preparation process of MMMs, including variation in polymer concentration, filler loading, volume of solution cast per membrane area, solvent type used and solvent evaporation rate, and to identify their impact on the CO2/CH4 separation performance of these membranes. Solvent evaporation rate proved to be the most critical synthesis parameter, directly influencing the performance and visual appearance of the membranes. Although less dominantly influencing the MMM performance, polymer concentration and solution volume also had an important role via control over the casting solution viscosity, particle agglomeration, and particle settling rate. Among all solvents studied, MMMs prepared with chloroform led to the best performance for this polymer-filler system. Chloroform-based MMMs containing 10 and 30 wt.% MOF-808 showed 73% and 62% increase in CO2 permeability, respectively, without a decrease in separation factor compared to unfilled membranes. The results indicate that enhanced gas separation performance of MMMs strongly depends on the cumulative effect of various synthesis parameters rather than individual impact, thus requiring a system-specific design and optimization.