Inertial Effects on the Stress Generation of Active Fluids

Suspensions of self-propelled bodies generate a unique mechanical stress owing to their motility that impacts their large-scale collective behavior. For microswimmers suspended in a fluid with negligible particle inertia, we have shown that the virial `swim stress' is a useful quantity to understand the rheology and nonequilibrium behaviors of active soft matter systems. For larger self-propelled organisms like fish, it is unclear how particle inertia impacts their stress generation and collective movement. Here, we analyze the effects of finite particle inertia on the mechanical pressure (or stress) generated by a suspension of self-propelled bodies. We find that swimmers of all scales generate a unique `swim stress' and `Reynolds stress' that impacts their collective motion. We discover that particle inertia plays a similar role as confinement in overdamped active Brownian systems, where the reduced run length of the swimmers decreases the swim stress and affects the phase behavior. Although the swim and Reynolds stresses vary individually with the magnitude of particle inertia, the sum of the two contributions is independent of particle inertia. This points to an important concept when computing stresses in computer simulations of nonequilibrium systems---the Reynolds and the virial stresses must both be calculated to obtain the overall stress generated by a system

Fabrication of highly dense SiN4 ceramics without additives by high pressure sintering

Silicon nitride (Si3N4) is one of candidate materials for the engineering ceramics which is used at high temperatures. The mechanical strengths of hot pressed or sintered Si2N4 ceramics containing some amount of additives, however, are deteriorated at elevated temperatures. To improve the high temperature strength of Si3N4 ceramics, an attempt to consolidate Si3N4 without additives was made by high pressure sintering technique. Scanning electron micrographs of fracture surfaces of the sintered bodies showed the bodies had finely grained and fully self-bonded sintered bodies were 310N sq m at room temperature and 174N/sq m at 1200 C

Range-Point Migration-Based Image Expansion Method Exploiting Fully Polarimetric Data for UWB Short-Range Radar

Ultrawideband radar with high-range resolution is a promising technology for use in short-range 3-D imaging applications, in which optical cameras are not applicable. One of the most efficient 3-D imaging methods is the range-point migration (RPM) method, which has a definite advantage for the synthetic aperture radar approach in terms of computational burden, high accuracy, and high spatial resolution. However, if an insufficient aperture size or angle is provided, these kinds of methods cannot reconstruct the whole target structure due to the absence of reflection signals from large part of target surface. To expand the 3-D image obtained by RPM, this paper proposes an image expansion method by incorporating the RPM feature and fully polarimetric data-based machine learning approach. Following ellipsoid-based scattering analysis and learning with a neural network, this method expresses the target image as an aggregation of parts of ellipsoids, which significantly expands the original image by the RPM method without sacrificing the reconstruction accuracy. The results of numerical simulation based on 3-D finite-difference time-domain analysis verify the effectiveness of our proposed method, in terms of image-expansion criteria

Studies on the metabolism of connective tissue

A granuloma pouch was formed on the back of rats by the original method of SELYE. Seven days when granuloma tissue reached its maximum, 35S labeled ChS, 59Fe labeled ChS-Fe, labeled ferric ammoninum citrate and colloidal 198Au were injected into the pouch and their absorption and organ distribution examined and compared with the results in the case where 59Fe labeled ferric ammoninum citrate and colloidal 198Au were injected into the gluteal muscle. 1. When 35S labeled ChS was injected into the granuloma pouch, radioactivity of the organs per gram tissue was high in the kidney, liver, bone marrow and spleen, in descending order. The maximum activity was seen 12 to 24 hours after injection, which is slow compared to the results obtained by KISHIDA in intraperitoneal and oral administration. 2. The absorption of Ch S-Fe by pouch where the iron is enveloped by the large ChS molecule, is slower than that of ferric ammonium citrate, an inorganic compound. 3. The uptake of Fe from the blood by bone marrow is larger when the increase of blood Fe ion concentration is slow, rater than when the increase is rapid. 4. When conoidal 198Au is injected into the pouch and injected into the&#34; gluteal muscle, the 198Au is phargocytozed by the reticuloendothelial system organs, the liver showing the largest uptake among all organs. 5. In the intramuscular injection of colloidal 198Au and 59Fe labeled ferric ammonium citrate, radioactivity of pouch fluid is lower than that of blood. However, the difference between the two is less in the case of colloidal 198Au. 6. In the granuloma ponch, radioactivity of the abdominal wall proves to be greater than that of the dorsal wall.</p

A theory for the phase behavior of mixtures of active particles

Systems at equilibrium like molecular or colloidal suspensions have a well-defined thermal energy k_BT that quantifies the particles' kinetic energy and gauges how “hot” or “cold” the system is. For systems far from equilibrium, such as active matter, it is unclear whether the concept of a “temperature” exists and whether self-propelled entities are capable of thermally equilibrating like passive Brownian suspensions. Here we develop a simple mechanical theory to study the phase behavior and “temperature” of a mixture of self-propelled particles. A mixture of active swimmers and passive Brownian particles is an ideal system for discovery of the temperature of active matter and the quantities that get shared upon particle collisions. We derive an explicit equation of state for the active/passive mixture to compute a phase diagram and to generalize thermodynamic concepts like the chemical potential and free energy for a mixture of nonequilibrium species. We find that different stability criteria predict in general different phase boundaries, facilitating considerations in simulations and experiments about which ensemble of variables are held fixed and varied

カンジダ特異的IgG(4)抗体と気管支喘息

Serum levels of Candida-specific IgG(4) antibodies were examined in 66 patients with bronchial asthma, relating to patient age and asthma severity. 1. The levels of Candida-specific IgG(4) antibodies were the highest in patients with 60+years of age, compared to the levels in cases with 0-39 and 40-59 years of age. 2. In cases with 40-59 years of age, the levels of Candida-specific IgG(4) were significantly higher in cases with long-term steroid therapy (severe intractable asthma) than in cases without steroid regimen. The results suggest that increased levels of Candida-specific IgG(4) were observed in relation to patient age and asthma severity.66例の気管支喘息症例を対象に，血清中カンジダ特異的lgG(4)抗体を測定し，その血中レベルと年齢および喘息の重症度との関連について検討を加えた。1．血清カンジダ特異的IgG(4)値は，0～39才，40～59才の年齢層にくらべ，60才以上の年齢層において高く，年齢によりその値が変動することが 示唆された。2．40～59才の年齢層では，血清カンジダ特異的IgG(4)は，ステロイド非使用例にくらべ，ステロイド依存性重症難治性喘息症例で有意の高値を示し，この年齢層では，カンジダ特異的IgG(4)抗体がその発症病態に関連している可能性が示唆された。以上，カンジダ特異的IgG(4)抗体の上昇は，高年齢層の症例（60才以上）では全般的に，また40～59才の年齢層で重症型喘息症例において観察されることが明らかにされた

臨床所見および検査成績からのスコアーによる喘息分類の特徴

Twenty six patients with bronchial asthma was classified by clinical symptoms and singns (clinical diagnosis), and the classification by clinical diagnosis was compared with the classification by a score calculated from clinical findings and examinations (score diagnosis). 1. Of 12 subjects with type Ia classified by clinical diagnosis, 8 cases with 0 to 49 ml/day of expectoration were evaluated as type Ia by score diagnosis. While four type Ia cases with 50 to 99ml/day of expectoration were calssified as type Ib by score diagnosis. The increased incidence of eosinophils in bronchoalveolar lavage fluid (BALF) of these four cases was similar to the incidence in type Ib cases with hypersecretion. 2. All of 6 subjects with type Ib by clinical diagnosis were estimated as type Ib by score diagnosis. 3. Of 8 cases with type II by clinical diagnosis, 7 cases were assessed as type II by score diagnosis. One case with type II by clinical diagnosis and with the score of 10 points was evaluated as questionable type II by score diagnosis.気管支喘息36例を対象に,臨床病態による喘息の分類（臨床診断）を試み,この分類と臨床所見および臨床検査より求めたスコアーによる分類（スコアー分類）との比較検討を行った｡1.臨床分類でIa.単純性気管支攣縮型と診断された12症例のうち,1日喀痰量0-49mlの8症例は,スコアー分類では同様にIa.型と分類された｡一方,1日喀痰量50-99mlの4症例はスコアー分類ではIb.型（気管支攣縮+過分泌型）と分類された｡これら4症例のBALF中好酸球増多はIb.型に類似した病態であった｡2.臨床診断によりIb.型に分類された6症例はいずれもスコアー診断でもIb.型と分類された｡3.臨床診断によりII.型（細気管支閉塞型）と分類された8症例のうち,7症例はスコアー診断でもII.型と分類されたが,1症例はスコアー10でII.型の診断基準に合わず,questionable II.型と診断された

Swim Pressure: Stress Generation in Active Matter

We discover a new contribution to the pressure (or stress) exerted by a suspension of self-propelled bodies. Through their self-motion, all active matter systems generate a unique swim pressure that is entirely athermal in origin. The origin of the swim pressure is based upon the notion that an active body would swim away in space unless confined by boundaries—this confinement pressure is precisely the swim pressure. Here we give the micromechanical basis for the swim stress and use this new perspective to study self-assembly and phase separation in active soft matter. The swim pressure gives rise to a nonequilibrium equation of state for active matter with pressure-volume phase diagrams that resemble a van der Waals loop from equilibrium gas-liquid coexistence. Theoretical predictions are corroborated by Brownian dynamics simulations. Our new swim stress perspective can help analyze and exploit a wide class of active soft matter, from swimming bacteria to catalytic nanobots to molecular motors that activate the cellular cytoskeleton

Superfluid Behavior of Active Suspensions from Diffusive Stretching

The current understanding is that the non-Newtonian rheology of active matter suspensions is governed by fluid-mediated hydrodynamic interactions associated with active self-propulsion. Here we discover an additional contribution to the suspension shear stress that predicts both thickening and thinning behavior, even when there is no nematic ordering of the microswimmers with the imposed flow. A simple micromechanical model of active Brownian particles in homogeneous shear flow reveals the existence of off-diagonal shear components in the swim stress tensor, which are independent of hydrodynamic interactions and fluid disturbances. Theoretical predictions from our model are consistent with existing experimental measurements of the shear viscosity of active suspensions, but also suggest new behavior not predicted by conventional models