Physical Testing and Surface Morphology Studies of Stainless Steel Irradiated with Xe Ions

6 MeV Xe ions were used to irradiate austenitic stainless steel at room temperature. Three displacement damage levels of 2,7 and 15 dpa were selected. Microstructure and surface morphology were characterized by transmission electron microscopy (TEM), positron annihilation lifetime spectroscopy (PLS) and atomic force microscope (AFM). PLS indicated that vacancy defects were introduced by ions irradiation. Vacancy clusters containing Xe will reduce the positron annihilation lifetime. High density of dislocation loops were observed by TEM. The dislocation loops size and density saturates after 7 dpa and the nature of dislocation loops can be deduced by its distribution. A surface step was detected by AFM measurements between irradiated region (uncovered) and unirradiated region (covered with nickel mesh). This indicate that the irradiation swelling phenomenon occur and swelling is closely related to irradiation damage. According to the step height, the volume swelling is about 1.7% and 4.2% after irradiated to 7 and 15 dpa.

Volume Dependence of Hydrogen Sorption and Desorption Diffusion in Cylindrical Polymers

We have investigated the volume effects on hydrogen diffusion properties in both sorption and desorption processes by employing a volumetric analysis technique. The total uptake (𝐶∞), total desorbed content (𝐶0), sorption diffusion coefficient (Ds), desorption diffusion coefficient (Dd), sorption and desorption equilibrium time of hydrogen in two rubbery polymers are determined relative to the diameter and thickness of the cylindrical sample in the two processes. 𝐶∞ and 𝐶0 do not demonstrate the appreciable volume dependence for all rubbers. The identical values in 𝐶∞ and 𝐶0 indicate the reversibility between sorption and desorption, which is interpreted by the occurrence of physisorption rather than chemisorption by introducing hydrogen molecules. The larger Dd values in the desorption process than Ds may be attributed to increased amorphous phase and volume swelling caused by increased hydrogen voids and polymer chain scission after decompression. The time to reach equilibrium in both sorption and desorption processes was found to be linearly proportional to the square of thickness above an aspect ratio of 3.7, which is consistent with the numerical simulations based on the solution of Fick’s law. This finding could be used to predict the equilibrium adsorption time depending on the sample size in the polymer.

Loops, TADs, Compartments, and Territories are Elastic and Robust to Dramatic Nuclear Volume Swelling

Layers of genome organization are becoming increasingly better characterized, but less is known about how these structures respond to perturbation or shape changes. Low-salt swelling of isolated chromatin fibers or nuclei has been used for decades to investigate the structural properties of chromatin. But, visible changes in chromatin appearance have not been linked to known building blocks of genome structure or features along the genome sequence. We combine low-salt swelling of isolated nuclei with genome-wide chromosome conformation capture (Hi-C) and imaging approaches to probe the effects of chromatin extension genome-wide. Photoconverted patterns on nuclei during expansion and contraction indicate that global genome structure is preserved after dramatic nuclear volume swelling, suggesting a highly elastic chromosome topology. Hi-C experiments before, during, and after nuclear swelling show changes in average contact probabilities at short length scales, reflecting the extension of the local chromatin fiber. But, surprisingly, during this large increase in nuclear volume, there is a striking maintenance of loops, TADs, active and inactive compartments, and chromosome territories. Subtle differences after expansion are observed, suggesting that the local chromatin state, protein interactions, and location in the nucleus can affect how strongly a given structure is maintained under stress. From these observations, we propose that genome topology is robust to extension of the chromatin fiber and isotropic shape change, and that this elasticity may be beneficial in physiological circumstances of changes in nuclear size and volume.

Optimization and Evaluation of Chemical Shrinking Agent for Deposits in Salt Cavern Gas Storage

Salt cavern gas storage is an important strategic method to shave the fluctuation of supply-demand of natural gas in China. However, due to low grades of salt beds, there remains lots of insoluble sediments accounting for 1/3 up to 2/3 of the storage capacity at the bottom of cavity. The use of chemical agent with the function of swelled-clay-shrinking is an effective method for enlarging actual cavity volume. Clay swelling and physical deposits experiments were conducted to select the suitable chemical shrinking agent and study the relation between salt rock and agent. A device simulating the leaching process of insoluble sediments was developed to evaluate different factors on residue deposits and XRD (X-Ray Diffraction) was used to analyze mineral compositions of various salt caverns. The results showed that the main controlling factor for the volume swelling of the bottom insoluble sediments in the salt cavity is the electrostatic repulsion. These hydrated cuttings carry a negative charge leading to the electrostatic repulsion between each other, which promotes the loose accumulations of these physical deposits. The relation between rock and shrinking agent is clarified and the selected chemical agent has an excellent adaptation in salt cavern gas storages through the tests above. In addition, the result provides an experimental basis for minimizing the volume of the salt carven sediments to store more natural gas.

Role of 5-HT in Cerebral Edema after Traumatic Brain Injury

The pathogenesis of edema after traumatic brain injury is complex including the destruction of micro-vessels and alterations in microcirculation around the primary injury and leakage of plasma constituents into the tissue, due to permeability changes of the vessel walls. Many functional molecules like histamine, serotonin, arachidonic acid, prostaglandins and thromboxane have been shown to induce blood–brain barrier (BBB) disruption or cell swelling. It is believed that released 5-HT binds to 5-HT2 receptors stimulating cAMP and prostaglandins in vessels that cause more vesicular transport in endothelial cells leading to serum component’s extravasation. The additional amount of serotonin into the tissue due to injury maintains the state of increased vascular permeability that ultimately causes edema. Serotonin is clearly involved in early cytotoxic edema after TBI. Reduction of serotonin in the nervous tissue reduces swelling and the milder cell changes in the brain or spinal cord of traumatized rats. Inhibition of serotonin synthesis before closed head injury (CHI) in rat models or administration of serotonin antiserum after injury attenuates BBB disruption and brain edema volume swelling, and brain pathology. Maintaining low serotonin levels immediately after injury may show neuroprotection and combat various secondary outcomes that occur after traumatic brain injury.

Triply-responsive OEG-based microgels and hydrogels: Regulation of swelling ratio, volume phase transition temperatures and mechanical properties

Thermally- and pH-responsive microgels (MGs) and hydrogels are fascinating network systems that have been applied in biomedical engineering and sensing. The volume-swelling ratio (Q) and the volume-phase transition temperatures (VPTTs)...

Swelling pressure of a sodium bentonite in solutions of different suction

In this study, the swelling pressure of unsaturated, compacted bentonite-sand mixture was measured, which the all samples had experiment in dying-wetting history in suction changing. This test program used Kunigel V1 as sodium type. Constant volume swelling test was conducted out that swelling pressure was measured using a developed apparatus. A pressure sensor was mounted in the swelling test apparatus. Previously, the all samples deformed due to suction change (i.e. drying-wetting process in suction). Two types were prepared before applying suction that were initial unsaturated condition and saturated condition on same initial dry density. Swelling pressure and adsorbed water amount was monitored in the test, which lasted for one month.

The study of selected properties of black poplar wood (Populus nigra L.) subjected to furfurylation and polymerization in lumen

The study of selected properties of black poplar wood (Populus nigra L.) subjected to furfurylation and polymerization in lumen. The aim of this work was studying black poplar wood (Populus nigra L.) selected properties modified with furfuryl alcohol and styrene. Maleic anhydride and glicydyl methacrylate were used as cross-linking agents. For modified wood samples the index of WPG, density, hardness, water absorbability, colour change and volume swelling were tested. Each test results were compared with values for unmodified black poplar wood. During furfurylation process density of poplar wood samples increased up to 1.3 times. Addition of maleic anhydride to furfurylation process caused increase of WPG index about 5-6 % and at the same time slightly decrease of wood Brinell hardness. Water absorbability and volume swelling of furfurylated poplar wood after 10080 min (168 h) of soaking in water were reduced more than 50% relative to unmodified wood. Polymerization in lumen with using styrene caused increase of density up to 2 times, increase of Brinell hardness up to 1.5 times, while WPG index was in the range from 50.8 to 116.6%. For polymerization in lumen process, water absorbability and volume swelling after 10080 min (168 h) of soaking in water were reduced more than half as well. Furfurylation caused intensive wood darkening when polymerization in lumen changed wood colour slightly. Addition of maleic anhydride to furfuryl alcohol caused an even greater darkening of the wood. The studies proved, that chemical modification significantly improved selected properties of poplar wood.

Swelling and water resistance of black poplar wood (Populus nigra L.) modified by polymerisation in lumen with styrene

Swelling and water resistance of black poplar wood (Populus nigra L.) modified by polymerisation in lumen with styrene. Polymerisation in lumen of black poplar (Populus nigra L.) was performed to improve wood properties related to interaction with water. Wood samples were modified with styrene or a mixture of styrene and maleic anhydride, using benzoyl peroxide as initiator. Polymerisation was conducted in closed vessels at a temperature up to 120 °C. Volume swelling and water absorbability of modified wood samples were measured. A significant decrease in the rate of water absorption was found, especially at the initial stage of soaking, resulting in 50 % decrease in volume swelling and 85 % decrease in water absorption.