Experimental Advances in Nanoparticle-Driven Stabilization of Liquid-Crystalline Blue Phases and Twist-Grain Boundary Phases

Recent advances in experimental studies of nanoparticle-driven stabilization of chiral liquid-crystalline phases are highlighted. The stabilization is achieved via the nanoparticles’ assembly in the defect lattices of the soft liquid-crystalline hosts. This is of significant importance for understanding the interactions of nanoparticles with topological defects and for envisioned technological applications. We demonstrate that blue phases are stabilized and twist-grain boundary phases are induced by dispersing surface-functionalized CdSSe quantum dots, spherical Au nanoparticles, as well as MoS2 nanoplatelets and reduced-graphene oxide nanosheets in chiral liquid crystals. Phase diagrams are shown based on calorimetric and optical measurements. Our findings related to the role of the nanoparticle core composition, size, shape, and surface coating on the stabilization effect are presented, followed by an overview of and comparison with other related studies in the literature. Moreover, the key points of the underlying mechanisms are summarized and prospects in the field are briefly discussed.

Characteristic core voxels in normal individuals revealed by hyperbolic disc embedding and k-core percolation on resting state fMRI

Hyperbolic disc embedding and k-core percolation reveal the core structure of the functional connectivity on resting-state fMRI (rsfMRI). Inter-voxel relations were visualized on embedded hyperbolic discs, and their core composition was traced using k-core percolation. Using rsfMRI data of 180 normal adults from the Human Connectome Project database, scale-free intervoxel connectivity represented by IC-voxels composition, while visualized on hyperbolic discs using 𝕊1/ℍ2 model, showed the expected change of the largest component decreasing its size on k-core percolation eventually yielding the core structures of individuals. This kmax-core voxels-ICs composition revealed such stereotypes of individuals as visual network dominant, default mode network dominant, and distributed patterns. Characteristic core structures of resting-state brain connectivity of normal subjects disclosed the distributed or asymmetric contribution of voxels to the kmax-core, which suggests the hierarchical dominance of certain IC subnetworks characteristic to subgroups of individuals at rest.

Water Uptake by Evaporating pMDI Aerosol Prior to Inhalation Affects Both Regional and Total Deposition in the Respiratory System

As pulmonary drug deposition is a function of aerosol particle size distribution, it is critical that the dynamics of particle formation and maturation in pMDI sprays in the interim between generation and inhalation are fully understood. This paper presents an approach to measure the evaporative and condensational fluxes of volatile components and water from and to solution pMDI droplets following generation using a novel technique referred to as the Single Particle Electrodynamic Lung (SPEL). In doing so, evaporating aerosol droplets are shown capable of acting as condensation nuclei for water. Indeed, we show that the rapid vaporisation of volatile components from a volatile droplet is directly correlated to the volume of water taken up by condensation. Furthermore, a significant volume of water is shown to condense on droplets of a model pMDI formulation (hydrofluoroalkane (HFA), ethanol and glycerol) during evaporative droplet ageing, displaying a dramatic shift from a core composition of a volatile species to that of predominantly water (non-volatile glycerol remained in this case). This yields a droplet with a water activity of 0.98 at the instance of inhalation. The implications of these results on regional and total pulmonary drug deposition are explored using the International Commission of Radiological Protection (ICRP) deposition model, with an integrated semi-analytical treatment of hygroscopic growth. Through this, droplets with water activity of 0.98 upon inhalation are shown to produce markedly different dose deposition profiles to those with lower water activities at the point of inspiration.

Development and pharmacokinetic evaluation of osmotically controlled drug delivery system of Valganciclovir HCl for potential application in treatment of CMV retinitis

Valganciclovir HCl (VGH) is the widely used drug for the treatment of Cytomegalovirus (CMV) retinitis infection with an induction dose of 900mg twice a day and a maintenance dose of 900mg. This required dose of the drug also leads to multiple side effects due to repeated administration. The research was highlighted to develop, formulate, optimize and evaluate Single-Core Osmotic Pump (SCOP) tablet of VGH with the dose of 450mg to reduce dosing frequency and associated side effects. . The decrease in dose also minimize the hepatic and nephrotic load. The optimized batch of formulation was subjected to comparative in vitro and in vivo evaluation. The tablet core composition is the primary influencer of the drug delivery fraction in a zero-order, whereas the membrane characteristics control the drug release rate. In-vivo pharmacokinetic studies revealed that the newly developed osmotic formulation has controlled zero-order release for 24 hours with a single dose of 450mg while the marketed formulation requires twice administration within 24 hours to maintain the plasma concentration in the therapeutic window. The developed formulation can be the promising option for the treatment of CMV retinitis with the minimum dose and dosing frequency.

Alginate-chitosan core-shell microcapsule cultures of hepatic cells in a small scale stirred bioreactor: impact of shear forces and microcapsule core composition

A small scale stirred bioreactor was designed and the effect of different agitation rates (30, 60 and 100 rpm) was investigated on HepG2 cells cultured in alginate-chitosan (AC) core-shell microcapsule in terms of the cell proliferation and liver-specific function. The microencapsulated hepatic cells could proliferate well when they were cultured for 10 days at 30 rpm while the cell-laden microcapsules showed no cell proliferation at 100 rpm in the bioreactor system. Albumin production rate, as an important liver function, increased also 1.8- and 1.5- fold under stirring rate of 30 rpm compared to the static culture and 60 rpm of agitation, respectively. Moreover, In comparison with the static culture, about 1.5-fold increment in urea production was observed at 30 rpm. Similarly, the highest expressions of albumin and P450 genes were found at 30 rpm stirring rate, which were 4.9- and 19.2-fold of the static culture. Addition of collagen to the microcapsule core composition (ACol/C) could improve the cell proliferation and functionality at 60 rpm in comparison with the cell-laden microcapsules without collagen. The study demonstrated the hepatic cell-laden ACol/C microcapsule hydrogel cultured in the small scale stirred bioreactor at low mixing rate has a great potential for mass production of the hepatic cells while maintaining liver-specific functions.

Contrasting patterns and co-occurrence network of soil bacterial and fungal community along depth profiles in cold temperate montane forests of China

Soil bacterial and fungal communities with different key ecological functions play an important role in the boreal forest ecosystem. Despite several studies have reported the microbial altitudinal distribution patterns, our understanding about the characteristics of the microbial community and the core composition of the microbiome in cold-temperate mountain forests is still limited. In this study, Illumina MiSeq sequencing was used to investigate the changes in soil bacterial and fungal communities in surface and subsurface soils along at an altitudinal gradient (from 830 m to 1300 m) on Oakley Mountain in the northern Greater Khingan Mountains. Altitude and soil depth had significant impacts on the relative abundance of Proteobacteria, Acidobacteria and Actinobacteria (dominant phylum for bacteria), and altitude had significant impacts on the Ascomycota, Basidiomycota and Mucoromycota (dominant phylum for fungi). The diversity of bacterial and fungal communities showed a monotonous decrease and increase with altitude. The influence of altitude on bacterial and fungal community composition was greater than that of soil depth. The variation of pH and dissolved organic nitrogen (DON) content in different altitudes were the main factors driving the bacterial and fungal community structure, respectively. There is no obvious difference between the network structure of surface and subsurface soil fungal communities, while the network of subsurface soil bacterial communities was more complex and compact than the surface layer. The network nodes mainly belonging to Proteobacteria and Actinobacteria are the key species in the two soil layers. Our results demonstrated that the altitude had a stronger influence on soil bacterial and fungal communities than soil depth, and bacterial and fungal communities showed divergent patterns along the altitudes and soil profiles.

Do Intraplate and Plate Boundary Fault Systems Evolve in a Similar Way with Repeated Slip Events?

<p>As repeated slip events occur on a fault, energy is partly dissipated through rock fracturing and frictional processes in the fault zone and partly radiated to the surface as seismic energy. Numerous field studies have shown that the core of intraplate faults becomes wider on average with increasing total displacement (and hence slip events). In this study we compile data on the fault core thickness, total displacement and internal structure (e.g., fault core composition, host rock juxtaposition, slip direction, fault type, and/or the number of fault core strands) of plate boundary faults to compare to intraplate faults (within the interior of tectonic plates). Fault core thickness data show that plate boundary faults are anomalously narrow by comparison to intraplate faults of the same displacement and that they remain narrow regardless of how much total displacement they have experienced or the local structure of the fault. By examining the scaling relations between seismic moment, average displacement and surface rupture length for plate boundary and intraplate fault ruptures, we find that for a given value of displacement in an individual earthquake, plate boundary fault earthquakes typically have a greater seismic moment (and hence earthquake magnitude) than intraplate events. We infer that narrow plate boundary faults do not process intact rock as much during seismic events as intraplate faults. Thus, plate boundary faults dissipate less energy than intraplate faults during earthquakes meaning that for a given value of average displacement, more energy is radiated to the surface manifested as higher magnitude earthquakes. By contrast, intraplate faults dissipate more energy and get wider as fault slip increases, generating complex zones of damage in the surrounding rock and propagating through linkage with neighboring structures. The more complex the fault geometry, the more energy has to be consumed at depth during an earthquake and the less energy reaches the surface.</p>

Seismic detection of the Martian core by InSight

<p><strong>Introduction:</strong>  A plethora of geophysical, geo-chemical, and geodynamical observations indicate that the terrestrial planets have differentiated into silicate crusts and mantles that surround a dense core. The latter consists primarily of Fe and some lighter alloying elements (e.g., S, Si, C, O, and H). There is strong evidence from measurements of the tidal deformation of the planet that the core of Mars is presently liquid.</p><p>The InSight mission aims at constraining these numbers via the RISE radio tracking experiment, and the SEIS seismic package. We used data recorded by SEIS for high SNR marsquakes between March 2019 and July 2020. The InSight Marsquake Service located these events in the distance range 27-40 degrees, based on identification of P- and S-body waves. Later studies identified a number of secondary, surface-reflected phases, which were used to constrain the upper mantle. We build upon the velocity models derived from these phase picks to constrain the time window in which to look for shear waves reflected from the core mantle boundary. Since shear waves cannot propagate in a fluid medium, the core mantle boundary (CMB) acts as a polarization filter, which fully reflects horizontally polarized shear waves back into the mantle. Shear waves reflected from the CMB, called ScS, are therefore expected to have a predominantly horizontal polarization at the receiver, with an azimuth orthogonal to the source direction. In this distance range, ScS is separated in time from any other body wave phase and therefore well-observable.</p><p><strong>Methods:</strong> We follow a two-step approach: 1. Confirm seismic arrivals as ScS, based on existing mantle velocity models. 2. Pick precise arrival times and invert those for mantle profiles and core size, constrained by mineralogy, moment of inertia and average density of the planet.</p><p><strong>Results: </strong>The inversion of travel times constrains the core radius to the upper end of pre-mission geophysics-based estimates. This value is compatible with estimates from the geodetic experiment RISE onboard and implies that a lower mantle is unlikely to be present. Moreover, a large core has important implications for core composition. Average retrieved core density is 6 g/cm^3, which implies that for a (Fe-Ni)-S composition, a sulfur content in excess of 18% is required. This is above the eutectic composition observed experimentally with potentially profound implications for the future crystallization of the Martian core, subject to further laboratory research of Fe-S data under core conditions.</p><p>All ScS candidate phases that were observed show significant seismic energy and a relatively flat spectrum above 0.1 Hz, which implies a low seismic attenuation throughout the mantle. The spectral character of direct S-phases for the distant-most events is consistent with that of the ScS-phases for more nearby events, which supports the identification of the arrivals as core-reflected.</p>