Toxicity Studies on Graphene-Based Nanomaterials in Aquatic Organisms: Current Understanding

Graphene and its oxide are nanomaterials considered currently to be very promising because of their great potential applications in various industries. The exceptional physiochemical properties of graphene, particularly thermal conductivity, electron mobility, high surface area, and mechanical strength, promise development of novel or enhanced technologies in industries. The diverse applications of graphene and graphene oxide (GO) include energy storage, sensors, generators, light processing, electronics, and targeted drug delivery. However, the extensive use and exposure to graphene and GO might pose a great threat to living organisms and ultimately to human health. The toxicity data of graphene and GO is still insufficient to point out its side effects to different living organisms. Their accumulation in the aquatic environment might create complex problems in aquatic food chains and aquatic habitats leading to debilitating health effects in humans. The potential toxic effects of graphene and GO are not fully understood. However, they have been reported to cause agglomeration, long-term persistence, and toxic effects penetrating cell membrane and interacting with cellular components. In this review paper, we have primarily focused on the toxic effects of graphene and GO caused on aquatic invertebrates and fish (cell line and organisms). Here, we aim to point out the current understanding and knowledge gaps of graphene and GO toxicity.

ZnO nanostructured materials for emerging solar cell applications

Zinc oxide (ZnO) has been considered as one of the potential materials in solar cell applications, owing to its relatively high conductivity, electron mobility, stability against photo-corrosion and availability at low-cost.

Выявление поверхностных состояний в топологических изоляторах Bi-=SUB=-2-x-=/SUB=-Sb-=SUB=-x-=/SUB=-Te-=SUB=-3-y-=/SUB=-Se-=SUB=-y-=/SUB=- по магнитотранспортным измерениям

In this paper, we studied the effect of the magnetic field and temperature on conductivity of Bi_2 ‒ _ x Sb_ x Te_3 – _ y Se_ y topological insulators of different composition to identify electronic surface states in these films. The experimental data can be explained based on the model with two types of charge carriers. Thermoactivation conductivity, electron or hole, is observed in the film bulk depending on the sample composition while metal-like electronic states are found on the surface. The noticeable contribution of surface topological states to the total conductivity opens up the possibility of studying them.

Noise Equivalent Power of Graphene–Superconductor-Based Optical Sensor

In this paper, the noise equivalent power (NEP) of optical sensors based on graphene–superconductor junctions in the voltage bias operation mode has been calculated. The effects of device parameters such as temperature, magnetic field and device resistance on the NEP of these detectors have been thoroughly investigated. By solving the related equations, graphene specific heat, thermal conductivity, electron–phonon interaction and responsivity of the detector have been obtained. Using the calculated parameters, the NEP of the device was obtained. The results show that at constant magnetic field the NEP will increase linearly by increasing device temperature. On the other hand, at constant temperature the behavior of NEP versus magnetic field is first increasing and then decreasing. Our calculations show that the optimal resistance of the device has a direct relation with respect to the device temperature, while in the investigated operating range the optimal resistance of device is almost independent of the magnetic field.

Thermally activated long range electron transport in living biofilms

The rate of extracellular electron transport through living, electrode-grown Geobacter sulfurreducens biofilms decreases with decreasing temperature, consistent with incoherent redox conductivity (electron hopping) among hemes of c-type cytochromes to conductive surfaces.