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Functionalized mesoporous silica nanoparticles for innovative boron-neutron capture therapy of resistant cancers
Get PDFTreatment resistance, relapse and metastasis remain critical issues in some challenging cancers, such as chondrosarcomas. Boron-neutron capture therapy (BNCT) is a targeted radiation therapy modality that relies on the ability of boron atoms to capture low energy neutrons, yielding high linear energy transfer alpha particles. We have developed an innovative boron-delivery system for BNCT, composed of multifunctional fluorescent mesoporous silica nanoparticles (B-MSNs), grafted with an activatable cell penetrating peptide (ACPP) for improved penetration in tumors and with gadolinium for magnetic resonance imaging (MRI) in vivo. Chondrosarcoma cells were exposed in vitro to an epithermal neutron beam after B-MSNs administration. BNCT beam exposure successfully induced DNA damage and cell death, including in radio-resistant ALDH+ cancer stem cells (CSCs), suggesting that BNCT using this system might be a suitable treatment modality for chondrosarcoma or other hard-to-treat cancers.journal articl
Matching times: Trying to improve the correlation between heavy metal levels in mosses and bulk deposition
Get PDFThe relationship between the concentrations of metals in moss tissues and atmospheric deposition is highly complex, resulting in a general lack of correlations between these two matrices. Here, we tried to improve the significance of the moss-bulk deposition (BD) relationship by eliminating the mismatch between the time that the moss tissue selected for analysis is exposed to atmospheric deposition, and the time during which BD is collected. For this, we analysed the concentrations of Cd, Hg and Pb in new grown tissue of Pseudoscleropodium purum and BD collected monthly, for one year, in 21 sampling sites (SS) under different degrees of pollution. Additionally, we assessed how different moss tissues, including native moss (green parts and new grown tissues of P. purum) and moss transplants of Sphagnum denticulatum, reflect BD to find out which moss tissues provide a better estimate of the atmospheric deposition of heavy metals. First of all, our results showed that eliminating the mismatch between native moss exposure time and BD collection period is not enough to improve their correlation. Environmental variation emerged as the main driver of tissue content variation altering the moss-BD relationship unpredictably. Secondly, native P. purum represents BD values better than devitalized transplants by displaying a greater number of significant correlations with BD. Specifically, green parts of P. purum generally represent better BD than new grown tissues. Overall, we conclude that neither native mosses nor transplants are good estimators of atmospheric heavy metal deposition rates. However, they are good qualitative indicators of the atmospheric deposition, by allowing us to differentiate SS subject to a wide range of pollution levels. Additionally, green parts of P. purum, and likely of other mosses with similar growth forms, should be used in passive biomonitoring studies to make results from different studies comparable.journal articl
The impact of porous walls on the rheology of suspensions
Get PDFWe study the effect of isotropic porous walls on a plane Couette flow laden with spherical and rigid particles. We perform a parametric study varying the volume fraction between 0 and 30%, the porosity between 0.3 and 0.9 and the non-dimensional permeability between 0 and 7.9 × 10⁻³ We find that the porous walls induce a progressive decrease in the suspension effective viscosity as the wall permeability increases. This behavior is explained by the weakening of the wall-blocking effect and by the appearance of a slip velocity at the interface of the porous medium, which reduces the shear rate in the channel. Therefore, particle rotation and the consequent velocity fluctuations in the two phases are dampened, leading to reduced particle interactions and particle stresses. Based on our numerical evidence, we provide a closed set of equations for the suspension viscosity, which can be used to estimate the suspension rheology in the presence of porous walls.journal articl
Complementary Ca2+ Activity of Sensory Activated and Suppressed Layer 6 Corticothalamic Neurons Reflects Behavioral State
Get PDFLayer 6 (L6) corticothalamic neurons project to thalamus, where they are thought to regulate sensory information transmission to cortex. However, the activity of these neurons during different behavioral states has not been described. Here, we imaged calcium changes in visual cortex L6 primary corticothalamic neurons with two-photon microscopy in head-fixed mice in response to passive viewing during a range of behavioral states, from locomotion to sleep. In addition to a substantial fraction of quiet neurons, we found sensory-activated and suppressed neurons, comprising two functionally distinct L6 feedback channels. Quiet neurons could be dynamically recruited to one or another functional channel, and the opposite, functional neurons could become quiet under different stimulation conditions or behavior states. The state dependence of neuronal activity was heterogeneous with respect to locomotion or level of alertness, although the average activity was largest during highest vigilance within populations of functional neurons. Interestingly, complementary activity of these distinct populations kept the overall corticothalamic feedback relatively constant during any given behavioral state. Thereby, in addition to sensory and non-sensory information, a constant activity level characteristic of behavioral state is conveyed to thalamus, where it can regulate signal transmission from the periphery to cortex.journal articl
An Investigation into the Genetic History of Japanese Populations of Three Starfish, Acanthaster planci, Linckia laevigata, and Asterias amurensis, Based on Complete Mitochondrial DNA Sequences
Get PDFCrown-of-thorns starfish, Acanthaster planci (COTS), are common in coral reefs of Indo-Pacific Ocean. Since they are highly fecund predators of corals, periodic outbreaks of COTS cause substantial loss of healthy coral reefs. Using complete mitochondrial DNA sequences, we here examined how COTS outbreaks in the Ryukyu Archipelago, Japan are reflected by the profile of their population genetics. Population genetics of the blue starfish, Linckia laevigata, which lives in the Ryukyu Archipelago, but not break out and the northern Pacific sea star, Asterias amurensis, which lives in colder seawater around the main Islands of Japan, were also examined as controls. Our results showed that As. amurensis has at least two local populations that diverged approximately 4.7 million years ago (MYA), and no genetic exchanges have occurred between the populations since then. Linckia laevigata shows two major populations in the Ryukyu Archipelago that likely diverged approximately 6.8 MYA. The two populations, each comprised of individuals collected from coast of the Okinawa Island and those from the Ishigaki Island, suggest the presence of two cryptic species in the Ryukyu Archipelago. On the other hand, population genetics of COTS showed a profile quite different from those of Asterias and Linckia At least five lineages of COTS have arisen since their divergence approximately 0.7 MYA, and each of the lineages is present at the Okinawa Island, Miyako Island, and Ishigaki Island. These results suggest that COTS have experienced repeated genetic bottlenecks that may be associated with or caused by repeated outbreaks.journal articl
Coupled Spin States in Armchair Graphene Nanoribbons with Asymmetric Zigzag Edge Extensions
No full textjournal articl
Geodesic string condensation from symmetric tensor gauge theory: A unifying framework of holographic toy models
Get PDFWe propose that there is a universal picture for different constructions of holographic toy models, and its continuous limit can be described by a gravitylike field theory, namely, the rank-2 U(1) gauge theory. First, we show that two different toy models for holography—the perfect tensor networks and the hyperbolic fracton models—are both equivalent to a picture of evenly distributed bit threads on geodesics in the anti–de Sitter space. We name this picture “geodesic string condensation.” It is actually a natural leading-order approximation to the holographic entanglement structure. Then, we reason that the rank-2 U(1) gauge theory with linearized diffeomorphism as its gauge symmetry, also known as a case of Lifshitz gravity, is the bulk field theory that gives rise to this picture. The Gauss's laws and spatial curvature require the geodesic gauge field lines, instead of the local loops (magnetic fields), to be the fundamental dynamical variables, which lead to geodesic string condensation. These results provide an intuitive way to understand the entanglement structure of gravity in anti–de Sitter/conformal field theory.journal articl
Response of Coral Reef Dinoflagellates to Nanoplastics under Experimental Conditions Suggests Downregulation of Cellular Metabolism
Get PDFPlastic products contribute heavily to anthropogenic pollution of the oceans. Small plastic particles in the microscale and nanoscale ranges have been found in all marine ecosystems, but little is known about their effects upon marine organisms. In this study, we examine changes in cell growth, aggregation, and gene expression of two symbiotic dinoflagellates of the family Symbiodiniaceae, Symbiodinium tridacnidorum (clade A3), and Cladocopium sp. (clade C) under exposure to 42-nm polystyrene beads. In laboratory experiments, the cell number and aggregation were reduced after 10 days of nanoplastic exposure at 0.01, 0.1, and 10 mg/L concentrations, but no clear correlation with plastic concentration was observed. Genes involved in dynein motor function were upregulated when compared to control conditions, while genes related to photosynthesis, mitosis, and intracellular degradation were downregulated. Overall, nanoplastic exposure led to more genes being downregulated than upregulated and the number of genes with altered expression was larger in Cladocopium sp. than in S. tridacnidorum, suggesting different sensitivity to nano-plastics between species. Our data show that nano-plastic inhibits growth and alters aggregation properties of microalgae, which may negatively affect the uptake of these indispensable symbionts by coral reef organisms.journal articl
Dealing With Large-Scale Spatio-Temporal Patterns in Imitative Interaction Between a Robot and a Human by Using the Predictive Coding Framework
Get PDFThis paper aims to investigate how adequate cognitive functions for recognizing, predicting, and generating a variety of actions can be developed through iterative learning of action-caused dynamic perceptual patterns. Particularly, we examined the capabilities of mental simulation of one's own actions as well as the inference of others' intention because they play a crucial role, especially in social cognition. We propose a dynamic neural network model based on predictive coding which can generate and recognize dynamic visuo-proprioceptive patterns. The proposed model was examined by conducting a set of robotic simulation experiments in which a robot was trained to imitate visually perceived gesture patterns of human subjects in a simulation environment. The experimental results showed that the proposed model was able to develop a predictive model of imitative interaction through iterative learning of large-scale spatio-temporal patterns in visuo-proprioceptive input streams. Also, the experiment verified that the model was able to generate mental imagery of dynamic visuo-proprioceptive patterns without feeding the external inputs. Furthermore, the model was able to recognize the intention of others by minimizing prediction error in the observations of the others' action patterns in an online manner. These findings suggest that the error minimization principle in predictive coding could provide a primal account for the mirror neuron functions for generating actions as well as recognizing those generated by others in a social cognitive context.journal articl
Understanding of the role of dilution on evaporative deposition patterns of blood droplets over hydrophilic and hydrophobic substrates
Get PDFBlood is a complex colloidal suspension which carries myriads of information about human health. Understanding the evaporation dynamics and its consequent deposition patterns have direct relevance in disease detection. We report evaporation dynamics of whole and diluted blood droplets over hydrophilic (glass) and hydrophobic (PDMS, polydimethylsiloxane) substrates. Our experiments show that blood drops evaporating on a hydrophilic substrate exhibit radial and orthoradial cracks in the coronal region and random cracks in the central region. Using Griffith’s energy criterion, we show that crack formation takes place when the capillary pressure and the resulting compressive stress inside the evaporating droplet exceeds critical stress which depends on the elastic modulus, interfacial energy, and the particle concentration of the system. The width of the coronal region (w), the film thickness (h) at the contact line, and the crack pitch (p) decrease with increasing blood dilution. In the dilution range of 2.0–0.8% HCT (hematocrit), the transition from the cracking to the non-cracking regime is observed, which can be attributed to inadequate compressive stress available even after the evaporation of the blood droplet is completed. For the hydrophobic substrate, buckling instead of cracking is observed for the whole blood droplets, which can be attributed to the distinct wetting and evaporation kinetics. The buckling of the blood drop on a hydrophobic surface is attributed to the competition between capillary pressure originated due to the formation of an elastic network of RBCs (red blood cells) and the menisci formed between adjacent RBCs, and the critical buckling pressure. With increasing blood dilution, a transition from buckling (between 21 and 42% HCT) to cracking (between 21 and 2.0% HCT) of the droplets, and eventually to the non-cracking regime (between 2.0 and 0.8% HCT) is observed. Our study unravels the interesting attributes about one of the important physico-chemical factors (i.e. % HCT) that affect the evaporation of blood droplets and the resulting deposition patterns on substrates with different hydrophobicity.journal articl