Simple Agitation Research Articles

Revisiting oxidation and reduction reactions for synthesizing a three-dimensional hydrogel of reduced graphene oxide.

An improvement to Hummers' method involving a cascade-design graphite oxidation reaction is reported to optimize safety and efficiency in the production of graphite oxide (GrO) and graphene oxide (GO). Chemical reduction using highly alkaline ammonia solution is a novel approach to synthesizing reduced graphene oxide (RGO). In this original research, we revisit the oxidation and reduction reactions, providing significant findings regarding the synthetic pathway to obtain a bioinspired water-intercalated hydrogel of RGO nanosheets. Influential factors in the graphite oxidation reaction, typically the exothermic reaction temperature and hydrogen peroxide effect, are described. Furthermore, the chemical reaction of GO reduction using highly alkaline ammonia solution (pH 14) was investigated to produce hydrated RGO nanosheets assembled in a hydrogel structure (97% water). Three-dimensional assembly and water intercalation are key to preserve the non-stacking state of RGO nanosheets. Therefore, ultrasound transmission to aqueous channels in the macroscopic RGO hydrogel vibrated and dispersed the RGO nanosheets in water. Analytical results revealed the single-layer nanostructures, functional groups, optical band gaps, optimized C/O ratios, particle sizes and zeta potentials of GO and RGO nanosheets. The reversible self-assembly of RGO hydrogels is essential for many applications, such as RGO coatings and polymer/RGO nanocomposites. In a water purification application, the RGO hydrogel was dispersed in aqueous solution by simple agitation and showed a high capacity for organic dye adsorption. After the adsorption, the RGO/dye particles were easily removed by filtration through ordinary cellulose paper. The process of adsorption and filtration is effective and inexpensive for practical environmental remediation. In summary, a bioinspired structure of RGO hydrogel is conceptualized for prospective nanotechnology.

Bottom-Up Assembling Hierarchical Enamel-Like Bulk Materials with Excellent Optical and Mechanical Properties for Tooth Restoration.

Enamel has good optical and mechanical properties because of its multiscale hierarchical structure. Biomimetic construction of enamel-like 3D bulk materials at nano-, micro-, mesh- and macro-levels is a challenge. A novel facile, cost-effective, and easy large-scale bottom-up assembly strategy to align 1D hydroxyapatite (HA) nanowires bundles to 3D hierarchical enamel structure with the nanowires bundles layer-by-layer interweaving orientation, is reported. In the strategy, the surface of oleate templated ultralong HA nanowires with a large aspect ratio is functionalized with amphiphilic 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Furtherly, the MDP functionalized HA nanowire bundles are assembled layer-by-layer with oriented fibers in a single layer and cross-locked between layers at a certain angle at mesoscale and macroscale in the viscous bisphenol A-glycidyl methacrylate (Bis-GMA) ethanol solution by shear force induced by simple agitation and high-speed centrifugation. Finally, the excessive Bis-GMA and ethanol are removed, and (Bis-GMA)-(MDP-HA nanowire bundle) matrix is densely packed under hot pressing and polymerized to form bulk enamel-like materials. The composite has superior optical properties and comparable comprehensive mechanic performances through a combination of strength, hardness, toughness, and friction. This method may open new avenues for controlling the nanowires assembly to develop hierarchical nanomaterials with superior properties for many different applications.

Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing

The major shortcoming of aqueous calcium phosphate suspensions used in biomedical applications is their unstable flow during delivery by mechanical means. In this study, microstructural changes and the resulting flow instabilities of aqueous β-TCP suspensions are demonstrated under both pressure-induced and drag-induced flow regimes and then remedied with the incorporation and subsequent gelling and preshearing of Carbopol 940, a biocompatible hydrogel. Mixing and dispersion of calcium phosphate particles into the hydrogel matrix was not efficient under simple agitation conditions. Swelling of the polymer chains was induced at approximately pH = 9.0 by water and particle intrusion within the opened-up coil structure due to deprotonation of the carboxylic acid groups by NaOH. As a result the composite material underwent a rapid viscoplastic transition into a doughy state which was not amenable to further processing without preshearing. Manual kneading converted the material into viscous state and enhanced the flow behavior significantly. Preshearing and probing the microstructure by mechanical spectrometer revealed multiple microstructural mechanisms responsible for the observed stable flow behavior, including improved dispersion of the particles, attrition of the polymeric network into microgel domains, enhanced adhesion and lubrication between the solid and liquid phase, crosslinking of the polymeric network. The net effect of these probable mechanisms was stiffening of the composite matrix, mobilization of solid particles and a marked enhancement in the stability of pressure-induced flow. The resistance of the material to liquid phase migration and its ability to undergo wall-slip and relax under stress were confirmed by simultaneous capillary rheometry and thermogravimetric analyses. The processing method enables improvements in the delivery of this composite material for injection and direct ink writing of scaffolds.

Photocatalytic activity of Co3O4@C enhanced by induction of amorphous cobalt-based MOF

A series of Co3O4@C-N (N = 1, 2, 3) composite photocatalysts were prepared by simple agitation and pyrolysis for degradation of organic dyes. The hollow macroscopic spherical structure of Co3O4@C-2 was constructed by adjusting the pyrolysis time. Compared with pure Co3O4, the carbon composite Co3O4@C-2 significantly enhanced light absorption in the UV and visible range, improved the electron transport efficiency and prevented the necessary photoexcited electron-hole pair recombination. Hence, the photocatalytic degradation rate of methylene blue (MB, 20 mg/L) reached 100% in 120 min under UV–vis light irradiation. Under the coupling of Co3O4 and graphitized carbon, Co3O4@C-2 obtained high structural stability, good reusability and low biotoxicity. Scavenging experiments and ESR test showed that •O2- radical was the active species for MB removal. After six cycles of tests, the photocatalytic efficiency of Co3O4@C-2 remained at 90.42%. The macroscopic spherical structure Co3O4@C-2 effectively avoids the problem of dispersion and recovery of powder catalyst, which also paves a path for the designing of candidate commercial photocatalyst with high efficiency and low consumption.

Oxidative depolymerization of kraft lignin assisted by potassium tert-butoxide and its effect on color and UV absorption

A chemically mild methodology was demonstrated to obtain decomposed lignin products via oxidative depolymerization. We effectively produced light-colored lignin materials with low molecular weight and narrow molecular weight distribution by simple agitation at ambient temperature and pressure in the presence of potassium tert-butoxide and gaseous oxygen. This oxidative depolymerization dissociated various lignin bonding structures and oxidized aliphatic hydroxyl groups of lignin, expanding conjugated system within the depolymerized lignin molecules. This chemical transformation resulted in the generation of effective chromophoric moieties to enhance the UV absorption property of the resulting depolymerized products, which showed a significant improvement in the sun protection capability.

Characterization of a new sustainable supramolecular solvent and application to the determination of oxy-PAHs in meat, seafood and fish tissues

In this study we develop a green treatment method based on supramolecular solvents (SUPRASs) made up of reverse aggregates of short/medium chain length alcohols (C6-C10) in mixtures of water and a sustainable organic solvent (methyl-tetrahydrofuran). SUPRASs ingredients have low toxicity and can be obtained from renewable sources. The new SUPRASs were characterized and its suitability for determination of oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) in food was tested. Analysis was made by liquid chromatography coupled to high resolution mass spectrometry. The method provided quantification limits in the range 0.4–4 ng g−1 with low consumption of reagents (200uL of SUPRAS per sample) and it was based on simple agitation and centrifugation without concentration/evaporation steps. All target compounds (except 11-H-benzo[b]fluoren-11-one) were found in 7 out of 19 samples, mainly in fish and seafood samples, with levels in the range n.d. – 8 ng g−1.

Delivering hydrophilic peptide inhibitors of heat shock protein 70 into cancer cells

Heat shock protein 70 (Hsp70) plays a major role in protein folding and has emerged as an attractive target in a wide range of cancers. Here we used a polymer nanogel to deliver two hydrophilic peptide inhibitors that block the interaction between the C-terminus of Hsp70 and heat shock organizing protein (HOP). The nanogels are able to load ∼200 wt% of the peptide inhibitors from solution via simple agitation at pH 7, and release them after cell uptake. Delivery of Hsp70 inhibitors to HCT116 cancer cells produced a clear Hsp70 inhibition phenotype: downregulation of client proteins glucocorticoid receptor (GR), immunophilins (FKBP51 and FKBP52), the protein kinase Akt-1, as well as the co-chaperone CHIP, and they induce cancer cell death. These results showcase the advantages of using versatile nanogels for delivery of hydrophilic cargo such as peptides and demonstrate the viability of these peptide inhibitors for targeting the Hsp70-HOP interaction in a cellular system.

Effect of ultrasound and chlorine dioxide on Salmonella Typhimurium and Escherichia coli inactivation in poultry chiller tank water

This study evaluated the application of ultrasound alone or combined with chlorine dioxide (ClO2) for Salmonella Typhimurium and Escherichia coli inactivation in poultry processing chiller tank water. A Full Factorial Design (FFD) 22 was conducted for each microorganism to evaluate the effect of ultrasound exposure time (x1: 1 to 9 min; fixed: 37 kHz; 330 W; 25 °C) using a bath, and ClO2 concentration (x2: 1 to 17 mg L−1) on microorganism count expressed in log CFU mL−1 in distilled water. Variable x2 had a negative effect on Salmonella Typhimurium (-5.09) and Escherichia coli (-2.00) count, improving the inactivation; while a x1 increase present no inactivation improvement, explaining the use of x1 lower level (1 min) and x2 higher level (17 mg L−1). The best condition for microorganism inactivation based on FFD was evaluated in chiller tank water (with organic matter) at 25, 16, and 4 °C; x1 was kept (1 min), however x2 was adjusted to obtain the same residual free chlorine (2.38 mg L−1) considering the ClO2 consumption by organic matter, achieving the value of 30 mg L−1. An inactivation of 49% and 31% were observed for Salmonella Typhimurium and Escherichia coli. When ultrasound was replaced by a simple agitation in the presence of ClO2, there was no inactivation for both microorganisms. Moreover, at poultry carcass pre-chilling (16 °C) and chilling (4 °C) conditions, the synergism of ultrasound combined with ClO2 was more pronounced, with microorganisms’ reductions up to 100%.

Management approach of patients with violent and aggressive behaviour in a district hospital setting in South Africa.

Aggressive and violent behaviour is very common in the hospital setting. Simple agitation may unpredictably progress to overt aggression and violence by any patient in the emergency centres (ECs). Aggressive behaviour often manifests in forms of verbally abusive language, verbal threats and intimidating physical behaviour. Violent behaviour comprises the intentional use of physical force or power, threatened or actual, against self (suicidal), or another (homicidal) or properties, group or community, that could potentially result in injuries, death, psychological harm or deprivation. Therefore, individuals with unusual agitation and aggression should be treated as an emergency in both the community and healthcare settings in order to mitigate the progression to physical violence. Whilst the incidence and prevalence of aggressive and violent behaviour are higher in individuals with an underlying mental disorder, substance use disorder or comorbid mental disorder and substance use disorder, other individuals can also present with these behaviours in the ECs. Therefore, the front-line clinicians must be knowledgeable and competent in managing patients with aggressive behaviour with a view to de-escalate the situation and preventing or curtailing violence. This paper presents an evidence-based approach for managing patients with aggressive and violent behaviour, including a review of the steps for admitting patients for assisted or involuntary care.

Novel Pumice@SO3H catalyzed efficient synthesis of 2,4,5-triarylimidazoles and acridine-1,8-diones under microwave assisted solvent-free path

In the present investigation, new heterogeneous catalyst pumice supported sulfonic acid (pumice@SO3H) was prepared from natural pumice by simple agitation with chlorosulphonic acid. The catalytic performance of a pumice@SO3H was investigated for the synthesis of 2,4,5-triaryl imidazoles and acridine-1,8-diones under microwave (MW) assisted solvent-free condition. The pumice@SO3H was stable and exhibits a good Brønsted acidic character. The beneficial characteristic features observed with this protocol are the recyclability of catalyst, the solvent free approach, the applicability to a wide variety of substrates, good to excellent yields, and easy to use. The catalyst pumice@SO3H with MW has been increased the green chemistry value of this method.

Effect of Agitation Method on the Nanosized Degradation of Polystyrene Microplastics Dispersed in Water.

Reports of marine organisms ingesting microplastics—formed from large plastic litter drifting in the marine environment by mechanical forces such as waves and photochemical processes initiated by sunlight, particularly ultraviolet rays—are increasing. However, the degradation process from microplastics to nanoplastics that are easily consumed by plankton located in the lower part of the food chain is not clear. Therefore, 200 nm diameter polystyrene (PS) latex particles—nanoparticle tracking analysis (NTA) calibration particles—dispersed in ultrapure deionized water were subjected to three types of agitation: rotation mixing, shaking, and flowing in addition to standing without agitation, and the physical degradation caused by agitation for 1 week at room temperature (23 °C) was evaluated. The degradation of the particles into nanosized particles was assessed by particle size distribution measurement using NTA and shape observation using field emission scanning electron microscopy (FE-SEM). In addition, the ratio of particle aggregation during incubation was calculated from the number of particles present in the region exceeding the particle size distribution range of the monodisperse particles before agitation with respect to the total number of particles. A shape change to a particle size of 100 nm or less was observed for the rotating and flowing of samples, and the influence of aggregation was suppressed to within 21% of the total particles calculated by NTA at the maximum. These results show that chemically stable PS can be degraded from micro- to nanosize with simple agitation in ultrapure deionized water.

Mechanochemical activation of antigorite to provide active magnesium for precipitating cesium from the existences of potassium and sodium

Much attention has been paid to deal with cesium from the serious concern over the environmental threat as a well-known radionuclide. Radioactive cesium is usually precipitated and concentrated from aqueous waste before the final processing such as verification at high temperature for permanent storage underground somewhere. Few choices are available due to the high solubility of almost all the cesium compounds. A new idea is developed to use insoluble magnesium source to increase the efficiency of precipitating cesium as struvite (CsMgPO4.6H2O). Activated antigorite (Mg3Si2O5(OH)4) by ball-milling was used together with phosphoric acid to combine cesium chloride and form struvite at nearly stoichiometric ratio, even by simple agitation at room temperature. It is more interesting to notice that other alkali metals of potassium and sodium do not form stable struvite phase and remain in solution, giving a very high selectivity of cesium removal over potassium and sodium. This method may be applied both in cesium removal from the radioactively contaminated source and cesium concentration for metallurgical processing.

Kinetics and mechanism of enhanced photocatalytic activity employing ZnS nanospheres/graphene-like C3N4

In this work, a novel photocatalyst ZnS nanospheres/graphene-like g-C3N4 (ZnS/GL-C3N4) nanocomposite was synthesized by a simple agitation method. Two-dimensional (2D) nanomaterial GL-C3N4, synthesized by thermal exfoliation from g-C3N4, showed large surface area and manifested efficient photocatalytic activity than bulk g-C3N4. ZnS nanospheres were well anchored and covered on the surface of GL-C3N4 nanosheets and a synergetic effect between the ZnS and GL-C3N4 could highly contributed to improvement of the light adsorption capability of GL-C3N4 as well as increasement of the separation efficiency of photon-generated e−-h+ pairs, therefore, enhancing its photocatalytic performance under the illumination of visible light. Methyl orange (MO, a kind of organic dyes which is hard to be degraded by pure C3N4) and tetracycline (TC, a representative broad-spectrum colorless antibiotic agent) were chosen as the targets of pollutants for degradation in this study. The optimum photocatalytic MO degradation of ZnS/GL-C3N4 (50%) was almost 3.48 and 12.4 times higher than that of pure ZnS and GL-C3N4, respectively. 91% TC was photodegraded in the presence of ZnS/GL-C3N4 (50%) and higher than that of GL-C3N4. Furthermore, kinetics and possible photocatalytic mechanism of MO degradation under visible light was proposed in detail. Except for the synergetic effect, the trapping experiments and ESR spectra demonstrated that not only O2− and holes, but also OH were active species playing an importing role in this system for effective degradation. Our research results open an easy pathway for developing highly efficiency photocatalyst.

Short communication: Improved method for centrifugal recovery of bacteria from raw milk applied to sensitive real-time quantitative PCR detection of Salmonella spp.

Centrifugation is widely used to isolate and concentrate bacteria from dairy products before assay. We found that more than 98% of common pathogenic bacteria added to pasteurized, homogenized, or pasteurized homogenized milk were recovered in the pellet after centrifugation, whereas less than 7% were recovered from raw milk. The remaining bacteria partitioned into the cream layer of raw milk within 5 min, and half-saturation of the cream layer required a bacterial load of approximately 5×108 cfu/mL. Known treatments (e.g., heat, enzymes or solvents) can disrupt cream layer binding and improve recovery from raw milk, but can also damage bacteria and compromise detection. We developed a simple, rapid agitation treatment that disrupted bacteria binding to the cream layer and provided more than 95% recovery without affecting bacteria viability. Combining this simple agitation treatment with a previously developed real-time quantitative PCR assay allowed the detection of Salmonella spp. in raw milk at 4 cfu/mL within 3 h. To our knowledge, this is the first report of an effective method for achieving high centrifugal recovery of bacteria from raw milk without impairing bacterial viability.

Large-scale delamination of multi-layers transition metal carbides and carbonitrides "MXenes".

Herein we report on a general approach to delaminate multi-layered MXenes using an organic base to induce swelling that in turn weakens the bonds between the MX layers. Simple agitation or mild sonication of the swollen MXene in water resulted in the large-scale delamination of the MXene layers. The delamination method is demonstrated for vanadium carbide and titanium carbonitride MXenes.

Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation.

Chain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering. Rapid vortex mixing induced chain exchange within minutes, as evidenced by a monotonic decrease in scattered intensity, whereas Couette flow and sparging did not lead to measurable chain exchange over the examined time scale of hours. The linear kinetics with respect to agitation time suggested a surface-limited exchange process at the air–water interface. These findings demonstrate the strong influence of processing conditions on block polymer solution assemblies.

Influence of the diffusion-layer thickness during electrodeposition on the synthesis of nano core/shell Sn–O–C composite as an anode of lithium secondary batteries

Electrodeposition of nano core/shell Sn–O–C composite anodes for lithium secondary batteries and improvement of cycle performances by a simple agitation technique.

Microcarriers Designed for Cell Culture and Tissue Engineering of Bone

Microspherical particulates have been an attractive form of biomaterials that find usefulness in cell delivery and tissue engineering. A variety of compositions, including bioactive ceramics, degradable polymers, and their composites, have been developed into a microsphere form and have demonstrated the potential to fill defective bone and to populate tissue cells on curved matrices. To enhance the capacity of cell delivery, the conventional solid form of spheres is engineered to have either a porous structure to hold cells or a thin shell to in-situ encapsulate cells within the structure. Microcarriers can also be a potential reservoir system of bioactive molecules that have therapeutic effects in regulating cell behaviors. Due to their specific form, advanced technologies to culture cell-loaded microcarriers are required, such as simple agitation or shaking, spinner flask, and rotating chamber system. Here, we review systematically, from material design to culture technology, the microspherical carriers used for the delivery of cells and tissue engineering, particularly of bone.

Preparation of Novel W/O Gel-Emulsions and Their Application in the Preparation of Low-Density Materials

A series of novel and stable water in oil (W/O) gel-emulsions was created by utilizing a new cholesteryl derivative, a low-molecular mass gelator (LMMGs), as a stabilizer. In the emulsions, n-heptane, n-octane, n-nonane, n-decane, tertiary butyl methacrylate (t-BMA), methyl methacrylate (MMA), or styrene can be used as a continuous phase, water as a dispersed phase, and the stabilizer in the continuous phase is only 2% (w/v). Importantly, the gel-emulsions could be prepared by simple agitation of the mixtures at room temperature, while heating, cooling, and addition of a cosolvent or other additional component are unnecessary. SEM and optical microscopy studies revealed the foam-like structures of the gel-emulsions. Rheological measurements demonstrated that the gel-emulsions are mechanically stable and exhibit typical viscoelastic properties. Surprisingly, the storage modulus, G', and the yield stress of the gel-emulsions with the alkanes as continuous phase decrease along with increasing the volume ratio of the dispersed phase, water, a property different from those of conventional gel-emulsions reported in the literature. From the viewpoint of application, the gel-emulsions as prepared are superior to others due to their simplicity in preparation, less amount of stabilizer needed, and the nonionic nature of the stabilizer, which must benefit practical applications. Furthermore, porous polymer monoliths could be prepared by polymerizing gel-emulsions with organic monomers as a continuous phase.

Collagen‐Coated Poly(l‐lactide‐co‐ɛ‐caprolactone) Film: A Promising Scaffold for Cultured Periosteal Sheets

We previously demonstrated that human periosteal sheets prepared on culture dishes function as an osteogenic "graft material" applicable to periodontal regenerative therapy. However, a lower level of initial adhesion of the excised periosteum tissue segments to culture dishes was a critical point that compromised the successful preparation of functional periosteal sheets. To improve on this weakness, we developed a transparent, biodegradable poly(L-lactide-co-ɛ-caprolactone) (LCL) film and tested its function as a scaffold and carrier of periosteal sheets. Human periosteum tissue segments excised from alveolar bone of healthy donors were cultured on type I atelocollagen-coated LCL films. Initial adhesion was examined by simple agitation. Cell outgrowth and in vitro mineralization were cytohistochemically examined. Osteogenic activity was histochemically examined in an animal implantation model using nude mice. Surface collagen-coating modified the hydrophobic nature of LCL and substantially improved the initial adhesion. Compared to cultures in plastic dishes, the growth rate was delayed in non-coated films, but not in collagen-coated films. In the trimming process for animal implantation, periosteal sheets were frequently detached from non-coated films, but not from collagen-coated films. Regardless of collagen-coating, LCL films did not cause any significant infiltration of inflammatory cells, or negatively impact mineralized tissue formation. Collagen-coating improved the initial adhesion of periosteum segments, which facilitated cell outgrowth and also handling efficiency on implantation. Therefore, we believe that once evaluated in human studies, our collagen-coated LCL film will contribute to improving the periodontal regenerative methodology with the application of cultured autologous periosteal sheets.