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In order to enhance the quality of spray-dried products or to adjust material properties for new applications, precise control of the aggregate structure is desirable. For the purpose of preparing hierarchically structured aggregates in the micrometer range, the formulation of the suspension can be specifically designed, utilizing defined nanoparticulate building blocks to achieve a highly uniform structure and porosity. Further adjustments can be made by combining two types of primary particles that differ in size. Thereby, a segregation effect is observed, where nanoparticles with larger particle sizes accumulate rather within the core of an aggregate and those with smaller particle sizes gather mainly near the outer surface, resulting in the formation of a shell. Furthermore, it is possible to produce tailor-made porosities using template particles (e.g. polystyrene) of different sizes as part of the coarse and fine fractions. The removal of these particles by a subsequent tempering process can lead to aggregates with defined porous structures and thus, to different mechanical aggregate properties that can be specifically set by adjusting the process and formulation parameters. As a result, a promising building kit for the hierarchically structure formation via spray drying processes were achieved.

For the detailed characterization structural and mechanical material properties were investigated, using e.g. mercury intrusion and SEM. The influence of the formulation parameters of the suspension (primary particle size and template content) on the micromechanical properties of the aggregate structures was systematically investigated by nanoindentation to elucidate structure-property relationships regarding, for example elastic and plastic deformation. As a result, a correlation could be established between the experimentally determined mechanical parameters and the aggregate porosities.

Such microstructures with defined properties can be used in a variety of applications, including catalysis or as drug carriers. For instance, these spray-dried aggregates were loaded with ibuprofen as an exemplary active pharmaceutical ingredient and investigated with regard to their drug release behavior.

The detailed behavior of carboxymethyl cellulose (CMC) as a dispersant in model anode slurries for lithium-ion batteries was investigated. Slurries with different graphite and CMC concentrations using three types of CMCs having different molecular weights were prepared, and changes in viscosity in the low shear rate range together with shear thickening in the high shear rate range were assessed. At a constant CMC concentration, the viscosities at low shear rates decreased as the graphite concentration was increased. Shear thickening was also more evident at low CMC concentrations and when using CMCs with lower molecular weights as well as at high graphite concentrations. These results suggest that, within the CMC concentration range investigated in the present work, the majority of the CMC was adsorbed on the graphite particles and this adsorbed CMC affected the rheological properties of the slurry. Increases in graphite concentration decreased the amount of adsorbed CMC per graphite particle, which in turn lowered the viscosity in the low shear rate range and enhanced shear thickening in the high shear rate range. The adsorbed CMC affected the slurry viscosity via electrostatic and steric interactions at low shear rates and acted as a buffer to inhibit shear thickening at high shear rates, primarily as a result of steric effects.

Recently focus of studies on the periodic precipitation in gels is shifting from evaluation of its spatio-temporal characteristics of the self-organized patterns to that of as a novel and viable method of synthesis of hierarchical monodispersed micro and nanomaterials in a single reactor. One of the parameters that profoundly affect the morphology, shape, size, and self-organization in the chemical systems is the supersaturation of the participating species. The Matalon-Packter (MP) law correlates the effect of the concentration of invading electrolytes to the spatial patterning in the Liesegang system. Although concentration and supersaturation have quantitative relations, the implications of supersaturation on the spatial arrangement of the band are not entirely understood. The present paper deals with studies on the periodically precipitating Co(OH)₂ in agar gel with respect to supersaturation of the participating reactants during the pattern formation. Varying inner and outer electrolytes concentrations were employed to determine spatial trends. Pattern image analysis was used to determine the precise location of the Liesegang bands. The supersaturation values showed a decreasing trend as the diffusion progressed outward. The present study led to the correlation between the supersaturation and the spacing coefficient.

Chemical polishing is an effective method to remove a subsurface damage layer with the advantages of no mechanical stress and no new subsurface damage. In this paper, we report a target polishing method that employs an anhydrous organic acid-ionic liquid-in-oil (OA-IL/O) microemulsion as the etching solution for chemical polishing of KDP crystals. OA-IL/O microemulsions were prepared with 1-butyl-3-methyl imidazolium bis [(trifluoromethyl) sulfonyl] imide ([Bmim]TF₂N) and bis (trifluoromethane sulfonimide) (TF₂NH) as the internal phase, castor oil as the external phase, TX-100 as the surfactant, and n-butanol as the co-surfactant. TF₂NH irreversibly reacts with KDP when microemulsion micelles driven by Brownian motion collide with the KDP surface. The organic salt products are removed by the ionic liquid in the microemulsion, resulting in the effective elimination of KDP. Moreover, the organic acid-ionic liquid solution will preferentially diffuse to the high points of the KDP surface and react with the KDP to achieve the target polishing. As a new type of water-free surface polishing technology, OA-IL/O microemulsion not only has the advantages of traditional CMP, but also avoids the recrystallization that can occur with water-in-oil microemulsions and achieves target polishing of the KDP crystal.

Intricate fluid displacement patterns, arising from the unstable growth of interfacial perturbations, can be driven by fluid viscoelasticity and surface tension. A soft glassy suspension ages, i.e. its mechanical moduli evolve with time, due to the spontaneous formation of suspension microstructures. The shear and time-dependent rheology of an aging suspension can be exploited to generate a wide variety of interfacial patterns during its displacement by a Newtonian fluid. Using video imaging, we report a rich array of interfacial pattern morphologies: dense viscous, dendritic, viscoelastic fracture, flower-shaped, jagged and stable, during the miscible and immiscible displacements of an aging colloidal clay suspension by Newtonian fluids injected into a radial quasi-two-dimensional geometry at different flow rates. We propose a new parameter, the areal ratio, which we define as the fully developed pattern area normalized by the area of the smallest circle enclosing it. We show that the natural logarithms of the areal ratios uniquely identify the distinct pattern morphologies, such that each pattern can be segregated in a three-dimensional phase diagram spanned by the suspension aging time, the displacing fluid flow rate, and interfacial tension. Besides being of fundamental interest, our results are useful in predicting and controlling the growth of interfaces during fluid displacements.

A sensitive electroactive platform relies directly upon the efficient and conductive interface. This work offers a simple and effective method for synthesizing NiCo₂O₄ using CTAB surfactant, suited for trace-level antibiotic detection. The route realized the controlled growth of tiny NiCo₂O₄ nanoboulders with an exposed interface. A comparative evaluation of the bimetallic nanostructures with their pristine compositional counterparts, i.e., NiO and Co₃O₄, supports its superior electrochemical characteristics based on the synergism of strong redox activity and conductivity from the bimetallic components. The NiCo₂O₄ nanoboulders exhibited strong electrochemical activity when configured as electrode material for detecting ofloxacin (OFL), a common antibiotic. The sensor exhibited excellent working linearity in a low-concentration range of 0.01–5 ​μM with a detection limit of 1 ​× ​10⁻³ ​μM for OFL. The kinetics of the NiCo₂O₄ further supported the electrocatalytic oxidation of OFL to be diffusion controlled with an estimated diffusion coefficient of 2.03310⁻⁶ ​cm² ​s⁻¹. Moreover, the constructed sensor is applicable for detecting OFL from environmental samples, reflecting its workability in complex real-environment.

The administration and delivery of pharmaceuticals faces a variety of well-known obstacles that result in limited biocompatibility and bioavailability. Efforts to improve these properties have often employed serum albumin, primarily due to its inherent biocompatibility and its ability to enhance the circulation times of pharmaceuticals. In this work, we have adapted a nanoparticle-formulation protocol, to produce a protein carrier of curcumin with bovine serum albumin. This was achieved by using a near-equimolar protein:curcumin ratio instead of the abundance of curcumin that would be normally used in a nanoparticle formulation. Photometric and quantitative analysis of this carrier showed an increased curcumin content in the produced aqueous solutions following the homogenization of bovine serum albumin (water) and curcumin (dichloromethane) phases. Albumin fluorescence studies indicated curcumin association near a tryptophan residue, without excluding the possibility of additional sites. Circular dichroism provided strong evidence of this association through the induced circular dichroism effect and showed that the secondary structure of bovine serum albumin was effectively maintained. Overall, this work presented a new means of facilitating the association of increased levels of curcumin with bovine serum albumin, which could potentially be used to generate additional non-covalent albumin carriers for pharmaceutical compounds.

The porous monolithic materials supporting non-noble metal nanoparticles that acted as catalysts have recently gained increasing attention due to their robust activity and regenerative ability, resulting in simple chemical progress. It is crucial for the catalytic performance that the monolithic supporters have a hierarchically porous structure while the non-noble metal nanoparticles show a good control of their dimensions and oxidation states. Herein this work reports the composite organosilica monolithic (OSM) foams containing non-noble metal like Cu-, Co-, or Ni-based nanoparticles. As-prepared the supporting non-noble metal nanoparticles organosilica monolithic foams could act as monolithic catalyst, showing the efficiently catalytic performance for the degradation of aromatic compounds. These monolithic catalysts were prepared via amino-functionalization of organosilica monolith with ethylenic groups, followed by supporting non-noble metal nanoparticles through a simple reduction process. The monolithic catalyst involved Cu-based nanoparticles (Cu/OSM) were obtained via reduction of Cu²⁺ using a mixture of NaBH₄ with and without the aid of polyvinylpyrrolidone K 90 (PVP), as denoted by Cu/OSM-N and Cu/OSM-P, respectively. It was demonstrated that the addition of PVP into the system caused the higher Cu content, the better distribution of the smaller Cu-based nanoparticles and a richer Cu(0) nanoparticles. Furthermore Cu/OSM-P exhibited high stability and durable activity, with approximately 95% conversion within 14 successive cycles, for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with excess NaBH₄ in an aqueous solution. This catalyst also showed a remarkable catalytic performance for the degradation of other organic aromatic dyes like methylene blue (MB), methyl orange (MO), rhodamine B (RhB) and even their mixture. In addition, Co/OSM-P and Ni/OSM-P fabricated with the same method also showed high catalytic performance for reduction of 4-NP. We believe that the strategy developed in this work is very useful for the simple, low-cost, and environmentally friendly preparation of porous composite monolithic catalysts containing non-noble metal nanoparticles.

Hypothesis

Water contamination is a serious global challenge and an on-site and out-of-lab method of assessment of contamination level is highly needed. In this study, we report the potential of using printable and biodegradable propelling sensors as indicators of water contamination in sewage wastewater.

Experiments

We used reactive 3D inkjet printing technology to fabricate self-propelling sensors which can quickly indicate the lowering of surface tension value caused by sewage contamination, and other surface tension lowering pollutants. The Z-shaped sensors were fabricated, with the dimensions of 2.0 ​mm at the longest side and 0.1 ​mm in thickness, from regenerated silk fibroin which is an environmentally friendly and biodegradable material. Inkjet printing has the advantage of high resolution and precise deposition of materials allowing the fabrication of small millimetre-sized sensors doped with a surface tension modifying polymer which acts as the ‘fuel’ to drive the sensors on the water surface via surface tension gradient.

Findings

Our results showed that the sensor's propulsion velocity decay rate is an excellent metric to indicate the presence and approximate level of sewage contamination.

The dispersion behavior of lithium cobalt oxide (LCO) and acetylene black (AB) particles in the preparation process of the cathode slurry of LiB is investigated from the rheological viewpoint. The cathode slurry is considered as the dispersion of coarse LCO particles in the viscoelastic AB slurry. Viscosity as well as loss modulus of the cathode slurry are estimated from those of the AB slurry using and compared the measured results. After forming the AB network structure or When AB content is high enough, LCO particles can enter and destroy the AB network structure. As a result, LCO particles and fragmented AB network structures are homogeneously mixed, exhibiting better discharge performance. Once the cathode slurry is excessively diluted, the LCO particles are excluded from the AB network structure, resulting in low discharge capacity. Over fragmentation using a high-shear device causes the AB network structure into too small segments, which also lowers the battery performance. Viscosity is helpful to understand the entrance of LCO particles into the AB network, and the storage modulus detects the destruction of the AB network structure during the preparation process of cathode slurry.