Semidilute Principle for Gels

Polymer gels such as jellies and soft contact lenses are soft solids consisting of three-dimensional polymer networks swollen with a large amount of solvent. For approximately 80 years, the swelling of polymer gels has been described using the Flory--Huggins mean-field theory. However, this theory is problematic when applied to polymer gels with large solvent contents owing to the significant fluctuations in polymer concentration. In this study, we experimentally demonstrate the superiority of the semidilute scaling law over the mean-field theory for predicting the swelling of polymer gels. Using the semidilute scaling law, we experimentally determine the universal critical exponent $\nu$ of the self-avoiding walk via swelling experiments on polymer gels. The experimentally obtained value $\nu\simeq 0.589$ is consistent with the previously reported value of $\nu\simeq 0.588$, which was obtained by precise numerical calculations. Furthermore, we theoretically derive and experimentally demonstrate a scaling law that governs the equilibrium concentrations. This scaling law contradicts the predictions made by de Gennes' $c^{*}$ theorem. A major deficiency of the $c^*$ theorem is that the network elasticity, which depends on the as-prepared state, is neglected. These findings reveal that the semidilute scaling law is a fundamental principle for accurately predicting and controlling the equilibrium swelling of polymer gels.Comment: 12 pages, 11 figure

Polymer Network Diffusion in Charged Gels

The swelling kinetics of charged polymer gels reflect the complex competition among elastic, mixing, and ionic contributions. Here, we used dynamic light scattering to investigate the collective diffusion coefficient of model gels, whose polymer network structure was controlled so that the three contributions were comparable. We demonstrate that the collective diffusion coefficient stems from the sum of elastic, mixing, and ionic contributions, without evident cross-correlations. The significant ionic contribution conforms to the Donnan equilibrium, which explains equilibrium electrical potential gradients in biological systems.Comment: 6+4 pages, 4+7 figure

A population analysis using Grid Square Statistics

publisher奈良地域統計データの利用においては、その初期から都道府県別統計や市区町村別統計が継続されているのに対して、さらに統計単位地域を細分して地域の実態をより詳細に表す「小地域統計」の利用歴は長いものではない。その中でも「地域メッシュ統計」は、比較的早くから実用化されてきた。単位地域は全て矩形となるので、不規則な図形となる行政境界線データを扱う必要がなく、ＧＩＳの発達を待たずとも利用できた。逆に、ＧＩＳが普及した昨今では、そのデータの長所にもかかわらず、十分な顧慮が行われなくなってきている。本稿では、地域メッシュ統計の現在の利用環境を考え、その意義を検討する。特に、学部の教育環境における利用の容易性を重点的に考察する

Percolation induced gel-gel phase separation in a dilute polymer network

Cosmic large-scale structures, animal flocks, and living tissues are non-equilibrium organized systems created by dissipative processes. Despite the uniqueness, the realization of dissipative structures is still difficult. Herein, we report that a network formation process in a dilute system is a dissipative process, leading to percolation induced gel-gel phase separation (GGPS) in a prominent miscible polymer-water system. The dilute system, which forms a monophase structure at the percolation threshold, eventually separates into two gel phases in a longer time scale as the network formation progresses. The dilute hydrogel with GGPS exhibits an unexpected mesoscale co-continuous structure and induces adipose growth in subcutaneous. The formation mechanism of GGPS and a cosmic large-scale structure is analogous, in terms of attractive interactions in a diluted system driving phase separation. This unique phenomenon unveils the possibility of dissipative structures enabling advanced functionalities and will stimulate research fields related to dissipative structures.Comment: 23+5 pages, 4+4 figure

Paclitaxel-Based Chemotherapy for Advanced Pancreatic Cancer after Gemcitabine-Based Therapy Failure: A Case Series of 5 Patients

Background/Objectives: Gemcitabine (GEM) is a gold-standard chemotherapy agent for advanced pancreatic cancer. Because of the malignant character of the disease, nearly all patients show disease progression despite treatment with GEM-based chemotherapy; therefore, second-line chemotherapy may be beneficial for these patients. We report a retrospective analysis of 5 patients with advanced pancreatic cancer, treated with a paclitaxel-containing regimen as second-, third- or fourth-line chemotherapy after various therapies, such as a GEM-based regimen, S-1 regimen, and chemoradiation. We retrospectively analyzed the efficacy and adverse events, and evaluated the paclitaxel-containing regimens. A review of the literature is also discussed. Results: The median overall survival from the start of salvage therapy was 10.7 months. The disease control rate of the paclitaxel-containing regimen according to RECIST criteria was 60%, including complete response in 0 patients, partial response in 3, and stable disease in 2. Two patients had malignant ascites at the start of this salvage therapy, and in both of them the ascites and clinical complaints improved. Grade 3 and 4 hematological adverse events were observed in 2 patients and 1 patient, respectively. Conclusion: Salvage paclitaxel-based therapy could be beneficial to advanced pancreatic cancer patients who maintain good performance status after several chemotherapy failures

Effect of bromide adsorption on electrowetting of Au electrode with hexadecane

Electrowetting of a Au/aqueous solution interface with hexadecane (HD) was largely affected by specific adsorption of Br? on the Au surface. The adsorption distinctly changed the potential dependence of the contact angle (θ) of HD droplets on a Au(1 1 1) electrode surface in line with electrocapillary relationship. Measurements of θ as a macroscopic observable, being sensitive to the atomic level change of the electrode surface such as surface reconstruction and Br? adsorption, allowed us to monitor the state of the Au/aqueous solution interface as demonstrated by pinpointing the Br? desorption potential. The amplitude of potential-controlled reshaping of a HD 1.0 μL droplet was enhanced by specific adsorption of Br?. The specific adsorption also affected HD microdroplets (<50 μm diameter ? 33 pL volume) in the same way as 1.0 μL droplets as revealed by in situ electrochemical fluorescence imaging measurements. Overall, ionic adsorption provides us with opportunities of fine control of the dynamics of oil droplet in an electrode potential range narrower than 1.5 V

Diving below the spin-down limit:constraints on gravitational waves from the energetic young pulsar PSR J0537-6910

We present a search for continuous gravitational-wave signals from the young, energetic X-ray pulsar PSR J0537-6910 using data from the second and third observing runs of LIGO and Virgo. The search is enabled by a contemporaneous timing ephemeris obtained using NICER data. The NICER ephemeris has also been extended through 2020 October and includes three new glitches. PSR J0537-6910 has the largest spin-down luminosity of any pulsar and is highly active with regards to glitches. Analyses of its long-term and inter-glitch braking indices provided intriguing evidence that its spin-down energy budget may include gravitational-wave emission from a time-varying mass quadrupole moment. Its 62 Hz rotation frequency also puts its possible gravitational-wave emission in the most sensitive band of LIGO/Virgo detectors. Motivated by these considerations, we search for gravitational-wave emission at both once and twice the rotation frequency. We find no signal, however, and report our upper limits. Assuming a rigidly rotating triaxial star, our constraints reach below the gravitational-wave spin-down limit for this star for the first time by more than a factor of two and limit gravitational waves from the l = m = 2 mode to account for less than 14% of the spin-down energy budget. The fiducial equatorial ellipticity is limited to less than about 3 x 10⁻⁵, which is the third best constraint for any young pulsar