Entanglement transition in rod packings

Random packings of stiff rods are self-supporting mechanical structures stabilized by long range interactions induced by contacts. To understand the geometrical and topological complexity of the packings, we deploy X-ray computerized tomography to unveil the structure of the packing. This allows us to define and directly visualize the spatial variations in the entanglement, a mesoscopic field that characterizes the local average crossing number, a measure of the topological complexity of the packing. We show that the entanglement field has information that is distinct from the density, orientational order, and contact distribution of the packing. We find that increasing the aspect ratio of the constituent rods in a packing leads to a proliferation of regions of strong entanglement that eventually percolate through the system, and this is correlated with a sharp transition in the mechanical response of the packing. We conclude with a tentative entanglement phase diagram for the mechanical response of dense rod packings that is likely relevant for a broad range of problems that goes beyond our specific study

Clinical Manifestations and Surgical Treatment Outcomes of Paranasal Sinus Osteoma

Background and Objectives Osteomas are the most common benign tumors of the nasal cavity and paranasal sinuses (PNSs). In this study, clinical features and imaging findings were analyzed in patients with osteoma confirmed by ostiomeatal unit (OMU) computed tomography (CT) and PNS CT, and the surgical treatment performed at our hospital was introduced. Methods The Severance Clinical Research Analysis Portal (SCRAP) service of Severance Hospital was used to collect research data. A total of 128 cases of osteomas of the nasal cavity or PNSs confirmed by OMU CT or PNS CT was retrospectively reviewed, including the location and size of the osteoma, clinical features, accompanying findings on imaging tests, and cases of surgical treatment. Results In this study, osteomas were found in about 0.55% of patients who underwent computed tomography. Osteomas were most frequently found in the ethmoid sinus, followed by the frontal sinus, fronto-ethmoid sinus, maxillary sinus, intranasal sphenoid sinus, and maxillary sinus-ethmoid sinus. Patients with osteomas complained of symptoms such as rhinorrhea, postnasal drip, nasal congestion, hyposmia, headache, visual disturbance, and lacrimal duct obstruction. Conclusion Surgical treatment was considered for patients presenting with severe headache, visual field symptoms, or accompanying rhinosinusitis. Surgery was performed by endoscopic or external approaches depending on location and size of the osteoma

Optimal diameter reduction ratio of acinar airways in human lungs

In the airway network of a human lung, the airway diameter gradually decreases through multiple branching. The diameter reduction ratio of the conducting airways that transport gases without gas exchange is 0.79, but this reduction ratio changes to 0.94 in acinar airways beyond transitional bronchioles. While the reduction in the conducting airways was previously rationalized on the basis of Murray's law, our understanding of the design principle behind the acinar airways has been far from clear. Here we elucidate that the change in gas transfer mode is responsible for the transition in the diameter reduction ratio. The oxygen transfer rate per unit surface area is maximized at the observed geometry of acinar airways, which suggests the minimum cost for the construction and maintenance of the acinar airways. The results revitalize and extend the framework of Murray's law over an entire human lung

The Draft Genome of an Octocoral, Dendronephthya gigantea

Coral reefs composed of stony corals are threatened by global marine environmental changes. However, soft coral communities of octocorallian species, appear more resilient. The genomes of several cnidarians species have been published, including from stony corals, sea anemones, and hydra. To fill the phylogenetic gap for octocoral species of cnidarians, we sequenced the octocoral, Dendronephthya gigantea, a nonsymbiotic soft coral, commonly known as the carnation coral. The D. gigantea genome size is similar to 276 Mb. A high-quality genome assembly was constructed from PacBio long reads (29.85 Gb with 108x coverage) and Illumina short paired-end reads (35.54 Gb with 128x coverage) resulting in the highest N50 value (1.4 Mb) reported thus far among cnidarian genomes. About 12% of the genome is repetitive elements and contained 28,879 predicted protein-coding genes. This gene set is composed of 94% complete BUSCO ortholog benchmark genes, which is the second highest value among the cnidarians, indicating high quality. Based on molecular phylogenetic analysis, octocoral and hexacoral divergence times were estimated at 544 MYA. There is a clear difference in Hox gene composition between these species: unlike hexacorals, the Antp superclass Evx gene was absent in D. gigantea. Here, we present the first genome assembly of a nonsymbiotic octocoral, D. gigantea to aid in the comparative genomic analysis of cnidarians, including stony and soft corals, both symbiotic and nonsymbiotic. The D. gigantea genome may also provide clues to mechanisms of differential coping between the soft and stony corals in response to scenarios of global warming

Myotis rufoniger genome sequence and analyses: M-rufoniger's genomic feature and the decreasing effective population size of Myotis bats

Myotis rufoniger is a vesper bat in the genus Myotis. Here we report the whole genome sequence and analyses of the M. rufoniger. We generated 124 Gb of short-read DNA sequences with an estimated genome size of 1.88 Gb at a sequencing depth of 66x fold. The sequences were aligned to M. brandtii bat reference genome at a mapping rate of 96.50% covering 95.71% coding sequence region at 10x coverage. The divergence time of Myotis bat family is estimated to be 11.5 million years, and the divergence time between M. rufoniger and its closest species M. davidii is estimated to be 10.4 million years. We found 1,239 function-altering M. rufoniger specific amino acid sequences from 929 genes compared to other Myotis bat and mammalian genomes. The functional enrichment test of the 929 genes detected amino acid changes in melanin associated DCT, SLC45A2, TYRP1, and OCA2 genes possibly responsible for the M. rufoniger's red fur color and a general coloration in Myotis. N6AMT1 gene, associated with arsenic resistance, showed a high degree of function alteration in M. rufoniger. We further confirmed that the M. rufoniger also has batspecific sequences within FSHB, GHR, IGF1R, TP53, MDM2, SLC45A2, RGS7BP, RHO, OPN1SW, and CNGB3 genes that have already been published to be related to bat's reproduction, lifespan, flight, low vision, and echolocation. Additionally, our demographic history analysis found that the effective population size of Myotis clade has been consistently decreasing since similar to 30k years ago. M. rufoniger's effective population size was the lowest in Myotis bats, confirming its relatively low genetic diversity

Facile Fabrication of Polyvinyl Alcohol/Edge-Selectively Oxidized Graphene Composite Fibers

Graphene derivatives are effective nanofillers for the enhancement of the matrix mechanical properties; nonetheless, graphene oxide (GO), reduced GO, and exfoliated graphene all present distinct advantages and disadvantages. In this study, polyvinyl alcohol (PVA) composite fibers have been prepared using a recently reported graphene derivative, i.e., edge-selectively oxidized graphene (EOG). The PVA/EOG composite fibers were simply fabricated via conventional wet-spinning methods; thus, they can be produced at the commercial level. X-ray diffractometry, scanning electron microscopy, and two-dimensional wide-angle X-ray scattering analyses were conducted to evaluate the EOG dispersibility and alignment in the PVA matrix. The tensile strength of the PVA/EOG composite fibers was 631.4 MPa at an EOG concentration of 0.3 wt %, which is 31.4% higher compared with PVA-only fibers (480.6 MPa); compared with PVA composite fibers made with GO, which is the most famous water-dispersible graphene derivative, the proposed PVA/EOG ones exhibited about 10% higher tensile strength. Therefore, EOG can be considered an effective nanofiller to enhance the strength of PVA fibers without additional thermal or chemical reduction processes

PEI-Functionalized Carbon Nanotube Thin Film Sensor for CO2 Gas Detection at Room Temperature

In this study, a polyethyleneimine (PEI)-functionalized carbon nanotube (CNT) sensor was fabricated for carbon dioxide detection at room temperature. Uniform CNT thin films prepared using a filtration method were used as resistive networks. PEI, which contains amino groups, can effectively react with CO2 gas by forming carbamates at room temperatures. The morphology of the sensor was observed, and the properties were analyzed by scanning electron microscope (SEM), Raman spectroscopy, and fourier transform infrared (FT-IR) spectroscopy. When exposed to CO2 gas, the fabricated sensor exhibited better sensitivity than the pristine CNT sensor at room temperature. Both the repeatability and selectivity of the sensor were studied

Avian mud nest architecture by self-secreted saliva

Mud nests built by swallows (Hirundinidae) and phoebes (Sayornis) are stable granular piles attached to cliffs, walls, or ceilings. Although these birds have been observed to mix saliva with incohesive mud granules, how such biopolymer solutions provide the nest with sufficient strength to support the weight of the residents as well as its own remains elusive. Here, we elucidate the mechanism of strong granular cohesion by the viscoelastic paste of bird saliva through a combination of theoretical analysis and experimental measurements in both natural and artificial nests. Our mathematical model considering the mechanics of mud nest construction allows us to explain the biological observation that all mud-nesting bird species should be lightweight. © 2021 National Academy of Sciences. All rights reserved.1