Water and ions in electrified silica nano-pores: a molecular dynamics study

Solid–liquid interfaces (SLIs) are ubiquitous in science and technology from the development of energy storage devices to the chemical reactions occurring in the biological milieu. In systems involving aqueous saline solutions as the liquid, both the water and the ions are routinely exposed to an electric field, whether the field is externally applied, or originating from the natural surface charges of the solid. In the current study a molecular dynamics (MD) framework is developed to study the effect of an applied voltage on the behaviour of ionic solutions located in a ∼7 nm pore between two uncharged hydrophilic silica slabs. We systematically investigate the dielectric properties of the solution and the organisation of the water and ions as a function of salt concentration. In pure water, the interplay between interfacial hydrogen bonds and the applied field can induce a significant reorganisation of the water orientation and densification at the interface. In saline solutions, at low concentrations and voltages the interface dominates the whole system due to the extended Debye length resulting in a dielectric constant lower than that for the bulk solution. An increase in salt concentration or voltage brings about more localized interfacial effects resulting in dielectric properties closer to that of the bulk solution. This suggests the possibility of tailoring the system to achieve the desired dielectric properties. For example, at a specific salt concentration, interfacial effects can locally increase the dielectric constant, something that could be exploited for energy storage

Towards local tracking of solvated metal ions at solid-liquid interfaces

The dynamics of individual solvated ions near solid surfaces is the driving force behind numerous interfacial processes, from electrochemical reactions to charge storage, mineral growth, biosignalling and bioenergetics. The precise system behaviour is delicately dependent on the atomistic and molecular details of the interface and remains difficult to capture with generalisable, analytical models. Reported dynamics can vary by orders of magnitude depending on microscopic details of the solvent, ions and/or surface chemistry. Experimentally, tracking single solvated ions as they move at or along interfaces remains highly challenging. This is, to some extent, offset by simulations that can provide precise atomistic insights, but usually over limited timescales. The aim of this review is to provide an overview of this highly interdisciplinary field, its achievements and remaining challenges, reviewing both experimental and computational results. Starting from the well accepted continuum description of dissolved ions at solid-liquid interfaces, we outline the challenges of deriving local information, illustrating the discussion with a range of selected studies. We explore the challenges associated with simultaneously achieving the spatial and temporal resolution needed to gain meaningful, yet contextual insights of single ions’ dynamics. Based on the current studies, we anticipate the future developments in the field, outlining remaining challenges and opportunities

Imaging Reality: A review of COVID-19 Pandemic

Recently, coronavirus disease 2019 (COVID-19) has been the main universal health concern and the most important challenge to the world. This disease affects all age groups, genders and, races. Due to lack of definitive medication detection of the disease in an early stage and prevention of its transmission plays an important role in its control. Transcription Polymerase Chain Reaction (RT-PCR) and chest computed tomography (CT) are the most common diagnostic methods for COVID-19. Besides a review on the general founding of the COVID-19 pandemic, we tried to collect a hand on report focusing on radiological knowledge and its applications, limitations, and instructions

Ions Adsorbed at Amorphous Solid/Solution Interfaces Form Wigner Crystal-like Structures.

When a surface is immersed in a solution, it usually acquires a charge, which attracts counterions and repels co-ions to form an electrical double layer. The ions directly adsorbed to the surface are referred to as the Stern layer. The structure of the Stern layer normal to the interface was described decades ago, but the lateral organization within the Stern layer has received scant attention. This is because instrumental limitations have prevented visualization of the ion arrangements except for atypical, model, crystalline surfaces. Here, we use high-resolution amplitude modulated atomic force microscopy (AFM) to visualize the lateral structure of Stern layer ions adsorbed to polycrystalline gold, and amorphous silica and gallium nitride (GaN). For all three substrates, when the density of ions in the layer exceeds a system-dependent threshold, correlation effects induce the formation of close packed structures akin to Wigner crystals. Depending on the surface and the ions, the Wigner crystal-like structure can be hexagonally close packed, cubic, or worm-like. The influence of the electrolyte concentration, species, and valence, as well as the surface type and charge, on the Stern layer structures is described. When the system parameters are changed to reduce the Stern layer ion surface excess below the threshold value, Wigner crystal-like structures do not form and the Stern layer is unstructured. For gold surfaces, molecular dynamics (MD) simulations reveal that when sufficient potential is applied to the surface, ion clusters form with dimensions similar to the Wigner crystal-like structures in the AFM images. The lateral Stern layer structures presented, and in particular the Wigner crystal-like structures, will influence diverse applications in chemistry, energy storage, environmental science, nanotechnology, biology, and medicine

Atopic dermatitis and the therapeutic methods: a literature review

Atopic dermatitis is an inflammatory skin disease that starts in the early life and usually persists by the end of life in 20% of cases. The disease shows multiple periods of relapse, and significantly affects the patient’s quality of life. The etiology of this disease is unknown, yet recent studies have reported incidence of immunological disorders and mutation in the filaggrin gene as the major causes. In some cases, concurrent incidence of infection with these inflammatory lesions reinforces the significance of treatment. Various methods of treatment such as emollients, corticosteroids, and calcineurin inhibitors are applied to manage this disorder. Traditional and complementary approaches may also help to control the disease. This disease is not usually easily controllable, thus requires full awareness of physicians on the underlying prospects of this disease. This review paper deals with the important aspects of the clinical perspectives and presents an integrative therapeutic approach for treating atopic dermatitis

Molecular details for deformation mechanisms of mineralised collagen fibrils from A coarse-grained molecular dynamics investigation of the role of mineral arrangement on the mechanical properties of mineralized collagen fibrils

Molecular details for deformation mechanisms of mineralised collagen fibril

Competition of opsonins and dysopsonins on the nanoparticle surface

International audienceThe schematic representation of opsonins and dysopsonins replacement on the GO surface

Evaluation of the effects of hyaluronic acid on poly (3-hydroxybutyrate)/chitosan/carbon nanotubes electrospun scaffold: structure and mechanical properties

In this study, a combination of poly (3-hydroxybutyrate) (PHB), chitosan (Cs), multiwall carbon nanotubes (MWNTs), and different concentrations of Hyaluronic Acid (HA) were electrospun. The results showed that the produced nanofibers are uniform. Incorporation of HA, Cs and MWNTs reduced the water contact angle and made the scaffolds more hydrophilic. The porosity of the scaffolds was in the range of 80-88%. The presence of MWNTs increased the tensile strength of scaffolds and different concentrations of HA had no much diverse effects. In conclusion, the PHB-Cs-MWNTs-HA 10% electrospun scaffold could be a good candidate for cartilage tissue engineering applications