Synthesis of metallic aluminum particles by electrolysis in aqueous solution

The present work proposes a method for fabricating metallic Al particles in aqueous solution. An aqueous colloidal solution was prepared from an aqueous aluminum nitrate nonahydrate solution by electrolysis using metallic Al plates as the anode and cathode under ultrasonic irradiation in water at 25–45 °C. The sizes of the particles in the colloidal solutions prepared at 25, 35, and 45 °C were 76.3, 77.0, and 84.7 nm, respectively. The powder obtained from the colloidal solution prepared at 25 °C was not crystalline. By contrast, the powders obtained from the colloidal solutions prepared at 35 and 45 °C had a crystal structure of cubic Al and crystal sizes of 55.7 and 59.3 nm, respectively. Thus, elevated temperatures promoted both particle growth and crystal growth, which was explained by higher temperatures increasing the frequency and energy of particle collisions. The metallic Al particles were chemically stable in both an aqueous solution and the ambient atmosphere. The chemically stable metallic Al particles are expected to be used as sources for fabricating materials related to fuels, energy storage, and pigments.

The structure and phase composition of the cermet charge in the Al‒Al2O3 system obtained using mechanical processing of aluminum powder in a planetary ball mill

The cermet charge in the Al‒Al2O3 system was obtained by mechanical processing (MP) in a planetary ball mill of aluminum powder of the industrial grade PAP-2 (GOST 5494‒95), consisting of flake particles of submicron thickness with a coating of stearin. Depending on the MP modes used, 4 types of charge were obtained, the bulk density of which varied from 0,33 to 1,1 g/cm3. For all types of charge, the synthesis of the α-Al2O3 phase was observed as a result of the exothermic reaction of the interaction of air oxygen with the surface of aluminum particles during the MP. It is also possible to form boehmite and gibbsite when the activated surface of Al particles interacts with atmospheric water vapor. The local X-ray spectral analysis (EDX) was used to detect X-ray amorphous carbon in the composition of the charge, the appearance of which is associated with the impact- shearing effect of grinding bodies, leading to the nucleation of X-ray amorphous carbon inclusions due to the termal destruction of stearin. The maximum bending strength of the sintered cermet was 550 MPa. This cermet is characterized by a discrete fracture: the formation of dimples as a result of the shear of layered packets under the action of tangential stresses. The revealed mechanisms cermet’s fractures allow us to establish the optimal modes of MP of powder compositions for obtaining various constructional elements from them.

Toxicity of Workplace Aluminum Particles: Insights from Earthworm (Eisenia fetida) Tests in Soil Mixtures

Lifestyle changes have led to increasing use of alternative materials in building construction, fabrication of furniture and household appliances. Apart from the associated light weight and aesthetics, Aluminum products endure various pressures that range from climatic factors to pest attacks; hence, they are more durable than wood and other conventional materials. Activities of fabricators are widespread in many Nigerian cities and these result in traces of Aluminum particles derived from cutting, shaping and surface filing. The resulting recalcitrant dust particles can exert adverse consequences on biota. Therefore, this study examined the effects of different levels of Aluminum particles on earthworm in soil mixtures by assessing their behaviour, mobility and mortality in a five-week ecotoxicity test. Worms became sluggish after only two-week exposure and this culminated in loss of mobility and ultimately mortality in exposed organisms. Mortality of worms was highest (80 – 100%) in soil mixtures with the most proportion of Aluminum particles and decreased correspondingly with contaminant levels. However, there was no mortality of worms in soil mixtures without any Aluminum particles. Lethal concentration (LC50) values of 2.564g/kg, 0.995g/kg and 0.851/kg were determined at two, four and five weeks, respectively. The results suggest that worms in the course of foraging in soil, can internalize contaminating Aluminum particles, which may lead to adverse consequences in exposed population. Considering the role of earthworms in breakdown of soil organic matter and nutrient cycling, indiscriminate disposal of Aluminum particles across various landscapes may have consequences on soil fertility, food security and sustainability.

Aluminum particles generated during millisecond electric pulse application enhance adenovirus-mediated gene transfer in L929 cells

Gene electrotransfer is an attractive method of non-viral gene delivery. However, the mechanism of DNA penetration across the plasma membrane is widely discussed. To explore this process for even larger structures, like viruses, we applied various combinations of short/long and high/low-amplitude electric pulses to L929 cells, mixed with a human adenovirus vector expressing GFP. We observed a transgene expression increase, both in the number of GFP-converted cells and GFP levels, when we added a low-voltage/millisecond-pulse treatment to the adenovirus/cell mixture. This increase, reflecting enhanced virus penetration, was proportional to the applied electric field amplitude and pulse number, but was not associated with membrane permeabilization, nor to direct cell modifications. We demonstrated that this effect is mainly due to adenovirus particle interactions with aggregated aluminum particles released from energized electrodes. Indeed, after centrifugation of the pulsed viral suspension and later on addition to cells, the activity was found mainly associated with the aluminum aggregates concentrated in the lower fraction and was proportional to generated quantities. Overall, this work focused on the use of electrotransfer to facilitate the adenovirus entry into cell, demonstrating that modifications of the penetrating agent can be more important than modifications of the target cell for transfer efficacy.