Characteristics of Radiogenic Heat Production of Widely Distributed Granitoids in Western Sichuan, Southeast Tibetan Plateau

AbstractInvestigating the genesis of geothermal resources requires a thorough understanding of the heat source mechanism, which is also a vital basis for the efficient exploration and utilization of geothermal resources. Situated in the eastern Himalayan syntax, western Sichuan is considered to be one of the main concentration regions of high-temperature geothermal resources in China. To date, various studies have been carried out to reveal the heat source and genesis of the abundant high-temperature resources in this area; however, studies on the contribution of the radioactive heat generated by the widely distributed granitoids to the high-temperature geothermal resources remain scarce. In order to resolve this knowledge gap, we attempted to obtain evidence from the geochemical data published in the literature in the past few decades. A total of 548 radiogenic heat production rate data were determined. The statistical data indicate that the average concentrations of the heat-producing elements U, Th, and K are 6.09±5.22 ppm, 26.74±16.78 ppm, and 3.51±0.82%, respectively. The calculated heat production values of the granitoids vary from 0.52 to 10.86 μW/m3, yielding an arithmetic average value of 3.74±2.15 μW/m3, which is higher than that of global Mesozoic–Cenozoic granites (3.09±1.62 μW/m3). Based on the heat production values, the capacity of the granitic batholiths to store heat was assessed, and the Dongcuo pluton was found to be the largest heat reservoir (382.88×1013 J/a). The distribution of the crustal heat flow was examined using the calculated heat production data and the stratigraphic structure obtained via deep seismic sounding in the study area. The results indicate that the crustal heat flow is 48.3–56.2 mW/m2, which is mainly contributed by the radioactive decay in the granitoids in the upper crust. The fact that it accounts for nearly half of the regional background heat flow indicates that the radiogenic heat from the granitoids is an important heat source for the formation of the thermal anomaly and the high-temperature geothermal resources in the study area. Thus, the results obtained in this study highlight the importance of the widely distributed granitoids to high-temperature geothermal resources in western Sichuan

Investigating the Effect of scyllo-Inositol Treatment on the Brain in a Mouse Model of Alzheimer's Disease

scyllo-Inositol is a potential therapeutic for the treatment of agitation and aggression in patients with Alzheimer's disease. scyllo-Inositol reduces aggregation of beta-amyloid peptide, reduces amyloid plaques, and reduces myo-inositol concentration in the brain. The change in gene expression in the brain of TgCRND8 mice after scyllo-inositol treatment has not been previously investigated. I hypothesized that scyllo-inositol treatment would cause changes in expression of genes involved in neurodegenerative diseases and neuropsychiatric disorders. Affymetrix gene expression microarrays were used to analyze changes in the hippocampus and cerebral cortex of TgCRND8 mice as well as in non-transgenic littermates after 30 days of scyllo-inositol treatment. Analysis of the data with the Database for Annotation, Visualization and Integrated Discovery and Ingenuity Pathways Analysis program showed gene expression changes in synaptic function, calcium, dopamine receptor, glutamate receptor, and myo-inositol signalling pathways. In light of these results, I concluded that my hypothesis was correct.M.Sc.2018-12-05 00:00:0

Micron scale mechanical response of fibrin hydrogels

How biological fibrous materials respond to forces and changes at the cellular scale is important for understanding what cells `feel' from their extracellular environment. The local mechanical property within a fibrin fiber network is dependent on the local structure of the network. Elastic force transmission through hydrogel depends on the arrangement of the fiber. A novel method for visualizing force transmission through this network is measuring the pixel fluctuation of individual fibers in the presence of an actively applied oscillation using embedded microbeads and optical tweezers. Optical tweezers can also be used for measuring local stiffness through active microrheology. After micropatterned crosslinking, fibrin hydrogels were shown to produce local stiffening directly and indirectly through strain hardening. This stiffening resulted in stiffness anisotropy and fiber alignment which MDA-231 cells were shown to respond to. Finally, a model of elastically connected nodes recapitulates some of the experimental observations such as fiber force transmission, strain hardening, and stiffness anisotropy when strained. Manipulating, measuring, and modelling of local stiffness changes in response to applied forces offers further insight into how cells sense their surroundings

Selective stiffening of fibrin hydrogels with micron resolution via photocrosslinking

Fibrin hydrogels are used as a model system for studying cell-ECM biophysical interactions. Bulk mechanical stiffness of these hydrogels has been correlated to mechanotransduction and downstream signaling. However, stiffness values proximal to cells can vary by orders of magnitude at the length scale of microns. Patterning of matrix stiffness at this spatial scale can be useful in studying such interactions. Here we present and evaluate a technique to selectively stiffen defined regions within a fibrin hydrogel. Laser scanning illumination activates ruthenium-catalyzed crosslinking of fibrin tyrosine residues, resulting in tunable stiffness changes spanning distances as small as a few microns and a localized compaction of the material. As probed by active microrheology, stiffness increases by as much as 25X, similar to previously observed stiffness changes around single cells in 3D culture. In summary, our method allows for selective modification of fibrin stiffness at the micron scale with the potential to create complex patterns, which could be valuable for the investigation of mechanotransduction in a biologically meaningful way. STATEMENT OF SIGNIFICANCE: Fibrin hydrogels are used as a naturally derived model to study interactions between cells and their surrounding extracellular matrix (ECM). ECM stiffness influences cell state. Cells in 3D culture considerably modify the stiffness of their pericellular space, which can be quite heterogeneous at the micron-scale. Here we present and evaluate a method to pattern stiffness within fibrin hydrogels using a laser scanning confocal microscope and selective photo crosslinking. We believe that this technique can aid future studies of cell-ECM interactions by enabling researchers to modify the pericellular distribution of stiffness

Patterned photocrosslinking to establish stiffness anisotropies in fibrous 3D hydrogels

Cells are known to constantly interact with their local extracellular matrix (ECM) and respond to a variety of biochemical and mechanical cues received from the ECM. Nonetheless, comprehensive understanding of cell-ECM interactions has been elusive. Many studies rely on analysis of cell behavior on 2D substrates, which do not reflect a natural cell environment. Further, lack of dynamic control over local stiffness anisotropies and fiber alignment hinders progress in studies in naturally derived fibrous 3D cultures. Here, we present a cell-safe method of patterned photocrosslinking, which can aid in studying biological hypotheses related to mechanotransduction in 3D hydrogels. As previously described by our group, ruthenium-catalyzed photocrosslinking (RCP) of selected ECM regions promotes localized increase in stiffness mediated by focused blue laser light in a confocal microscope. In this study, we further demonstrate that RCP can induce localized strain stiffening and fiber alignment outside of the selected crosslinked region and induce stiffness anisotropy biased towards the direction of fiber alignment. MDA-MB-231 cells are shown to respond to RCP-induced changes in local ECM architecture and display directional bias towards the direction of fiber alignment, as compared to control cells. Further, the effect of patterned crosslinking on a stiffness landscape is measured using multi-axes optical tweezers active microrheology (AMR) with backscattered laser beam illumination. AMR validates RCP as a suitable tool for creating distinct stiffness anisotropies which promote directed migration of cells, further underscoring the usefulness of RCP in cell-ECM studies. STATEMENT OF SIGNIFICANCE: Studies on cell-ECM interactions in 3D cultures have often been hindered by the lack of available tools to dynamically alter local ECM stiffness and fiber alignment. Here, we present a non-invasive, cell-safe and easily applicable method of patterned photocrosslinking, which can aid in studying biological hypotheses in fibrous 3D hydrogels. Ruthenium-catalyzed crosslinking (RCP) of selected fibrin ECM regions promotes localized increase in stiffness and creates distinct stiffness anisotropies in the presence of the focused blue laser light. Outside of the crosslinked region, RCP causes fiber alignment and strain stiffening in the ECM, verified using multi-axes optical tweezers active microrheology (AMR). Following RCP, human breast cancer MDA-MB-231 exhibit directed cell migration, validating usefulness of this method in cell-ECM studies

WL-Reviver: A Framework for Reviving any Wear-Leveling Techniques in the Face of Failures on Phase Change Memory

Abstract—While Phase Change Memory (PCM) has emerged as one of most promising complements or even replacements of DRAM-based memory, it has only limited write endurance. Because of uneven write distribution, PCM is highly likely to have early failures, which can spread over the chip space and leave the entire chip unusable. Wear leveling is an indispensable technique to even out wear caused by the writes. However, because of process variation early failure cannot be fully avoided. State-of-the-art wear-leveling schemes, such as Start-Gap and Security Refresh, cease to function once even a single block failure occurs because their designs require persistent writable address space for wear leveling operations. Existent solutions attempting to address the problem demand substantial OS supports, such as explicit space allocations and data migrations. The demand on substantial OS cooperatio

Evolution of the Vertebrate Resistin Gene Family

<div><p>Resistin (encoded by <i>Retn</i>) was previously identified in rodents as a hormone associated with diabetes; however human resistin is instead linked to inflammation. Resistin is a member of a small gene family that includes the resistin-like peptides (encoded by <i>Retnl</i> genes) in mammals. Genomic searches of available genome sequences of diverse vertebrates and phylogenetic analyses were conducted to determine the size and origin of the resistin-like gene family. Genes encoding peptides similar to resistin were found in Mammalia, Sauria, Amphibia, and Actinistia (coelacanth, a lobe-finned fish), but not in Aves or fish from Actinopterygii, Chondrichthyes, or Agnatha. <i>Retnl</i> originated by duplication and transposition from <i>Retn</i> on the early mammalian lineage after divergence of the platypus, but before the placental and marsupial mammal divergence. The resistin-like gene family illustrates an instance where the locus of origin of duplicated genes can be identified, with <i>Retn</i> continuing to reside at this location. Mammalian species typically have a single copy <i>Retn</i> gene, but are much more variable in their numbers of <i>Retnl</i> genes, ranging from 0 to 9. Since <i>Retn</i> is located at the locus of origin, thus likely retained the ancestral expression pattern, largely maintained its copy number, and did not display accelerated evolution, we suggest that it is more likely to have maintained an ancestral function, while <i>Retnl</i>, which transposed to a new location, displays accelerated evolution, and shows greater variability in gene number, including gene loss, likely evolved new, but potentially lineage-specific, functions.</p></div