Simulation of the Infiltration of Fractured Rock in the Unsaturated Zone

We study infiltration of rainwater into fractured rock and the accompanying capillary exchange processes between fractures and matrix, hereafter referred to as fracture–matrix transfer (FMT). Its influence on the velocity of the wetting front for uniform and variable aperture fractures is of prime interest because it determines the penetration depth of infiltration pulses. FMT is modelled explicitly in a discrete fracture and matrix (DFM) framework realised using a hybrid finite element–finite volume discretisation with internal boundaries. The latter separate the fracture mesh from the rock matrix mesh with the benefit that the flow that occurs within the minute fracture subvolume can be tracked with great accuracy. A local interface solver deals with the transient nonlinear aspects of FMT, including spontaneous imbibition of the rock matrix. Two- and three-dimensional heuristic test cases are used to illustrate how FMT affects infiltration. For the investigated scenario, we find that—beyond a critical fracture aperture around 5–10-mm—infiltration rate is no longer affected by FMT. Fracture aperture variations promote in-fracture-plane fingering, with counter-current flow of water (downward) and air (upward). Fracture flow interacts with FMT in a complex fashion. For systems with a small fracture porosity (≤0.01%), our results suggest that intense, hour-long rainfall events can give rise to tens-of-meter-deep infiltration, depending on fracture/matrix properties and initial saturation of the fractured rock mass.

Permafrost

Permafrost is permanently frozen ground that remains continuously below 0 °C for two or more years. The upper level of permafrost, the permafrost table, can occur within a centimeter of the ground surface or at a depth of several meters. The active layer, which thaws each summer, overlies permafrost. Permafrost underlies about a quarter of the northern hemisphere and can form in sediment or bedrock and on land or under the ocean. Permafrost forms incrementally and, in the regions where it is up to 1 km thick, permafrost can represent thousands of years of formation. Permafrost is present at high latitudes and high altitudes. In these regions, permafrost can be described as continuous, discontinuous, sporadic, or isolated. Continuous permafrost forms at mean annual air temperatures below -5 °C and is laterally continuous, regardless of surface aspect or material. Discontinuous permafrost forms where the mean annual air temperature is between -2 and -4 °C, allowing permafrost to persist in 50 to 90 percent of the landscape. Permafrost is sporadic where 10 to <50 percent of the landscape is underlain by permafrost and mean annual air temperature is between 0 and -2 °C. Permafrost is considered isolated where less than 10 percent of the landscape is underlain by permafrost. When it is present, permafrost creates unique conditions. Permafrost forms an impermeable layer beneath the active layer, for example, which limits the rooting depth of plants and prevents infiltration by water during the summer. The lack of deep infiltration can facilitate formation of extensive wetlands in high-latitude areas that receive relatively little precipitation. Permafrost degradation (thaw) creates diverse environmental hazards, including instability of the ground surface that affects infrastructure and fluxes of water, sediment, and organic matter entering rivers, lakes and oceans. Permafrost degradation releases frozen microbes, some of which are pathogens, and organic carbon. Permafrost degradation also influences the geographic range of plants and animals and thus ecosystem processes and biotic communities. The greatest concern with permafrost degradation at present, however, is the potential for releasing significant carbon into the atmosphere. Globally, soils are the largest terrestrial reservoir of carbon and permafrost soils are the single largest component of the carbon reservoir. Carbon released by degrading permafrost can enter the atmosphere as the greenhouse gases carbon dioxide and methane, or the carbon can be taken up by plants or transported by rivers to the ocean and buried in marine sediments. The balance among these different pathways is largely unknown, but carbon release to the atmosphere presents a serious threat as a mechanism to enhance global warming.

Physical limits to meltwater penetration in firn

Processes governing meltwater penetration into cold firn remain poorly constrained. Here, in situ experiments are used to develop a grain-scale model to investigate physical limitations on meltwater infiltration in firn. At two sites in Greenland, drilling pumped water into cold firn to >75 m depth, and the thermo-hydrologic evolution of the firn column was measured. Rather than filling all available pore space, the water formed perched aquifers with downward penetration halted by thermal and density conditions. The two sites formed deep aquifers at ~40 m depth and at densities considerably less than the air pore close-off density (~725 kg m−3 at −18°C, and ~750 kg m−3 at −14°C), demonstrating that some pore space at depth remains inaccessible. A geometric grain-scale model of firn is constructed to quantify the limits of a descending fully saturated wetting front in cold firn. Agreement between the model and field data implies the model includes the first-order effects of water and heat flow in a firn lattice. The model constrains the relative importance of firn density, temperature and grain/pore size in inhibiting wetting front migration. Results imply that deep infiltration, including that which leads to firn aquifer formation, does not have access to all available firn pore space.

Amine Modification of Calcium Phosphates by Low-Pressure CH4/N2/He Plasma for Bone Regeneration

Calcium phosphates are promising materials for artificial bone but lack of satisfied osteogenic ability on their surfaces. In the present study, we applied a low-pressure plasma technology to chemically (amine) modify the surface of calcium phosphates (hydroxyapatite or beta-tricalcium phosphate) using a CH4/N2/He plasm gas mixture to improve their osteogenic ability. The CH4/N2/He plasma treatment produced a thin, stable amine-rich carbon polymer on the surface of the calcium phosphates, and enhanced hydrophilicity, deep infiltration of cells into porous calcium phosphates, cell adhesion and osteogenic differentiation on the surface of calcium phosphates. In a rat calvarial defect model, the CH4/N2/He plasma treatment afforded calcium phosphates a significant higher bone regeneration capacity. Together, these results suggest that surface modification of calcium phosphates with CH4/N2/He plasma might improve osteogenic ability of calcium phosphates in vitro and in vivo.

Junctional Adhesion Molecule-Like Protein Promotes Tumor Progression and Metastasis via p38 Signaling Pathway in Gastric Cancer

Junctional adhesion molecule-like protein (JAML), a newly discovered junctional adhesion molecule (JAM), mediates the adhesion and migration processes of various immune cells and endothelial/epithelial cells, ultimately regulating inflammation reaction. However, its role in tumors remains to be determined. The expression of JAML was examined in gastric cancer (GC) and peritumoral tissues from 63 patients. The relationship between JAML expression and clinical characteristics was also observed. In vitro, GC cell migration and proliferation were assessed by wound healing assay, transwell migration assay and EdU incorporation assay. Immunohistochemical staining results showed that JAML expression level was higher in GC tissues than in peritumoral tissues. High expression of JAML in cancer tissues was associated with worse cell differentiation, local lymph node involvement, deep infiltration, and advanced stage. In vitro, we found that JAML silencing inhibited GC cell migration and proliferation, while JAML overexpression promoted GC cell migration and proliferation, partially via p38 signaling. Taken together, our study revealed a critical role for JAML to promote GC cell migration and proliferation. JAML might be a novel diagnostic biomarker and therapeutic target for GC.

Terrestrial hydroclimatic variability in basins of Southern Siberia driven by different states of permafrost degradation

&lt;p&gt;Changes in the cryosphere caused by global warming are expected to alter the hydrologic system, with inevitable consequences for freshwater availability to humans and ecosystems. Quantitative understandings of the historical hydrologic changes in response to permafrost degradation is essential for projecting future changes with respect to the continuing and possibly intensifying warming. Here we investigate past hydro-climatic changes over three southern Siberian basins with diverse permafrost properties: in the Selenga catchment, all three permafrost types occur, i.e., discontinuous, sporadic and isolated permafrost; the Lena Basin (at gauge Tabaga) is mostly underlain by discontinuous permafrost, while the Aldan is dominated by continuous permafrost.&lt;/p&gt;&lt;p&gt;Based on the reconstruction of terrestrial water storage changes (TWS) from the GRACE satellite mission and hydro-climatic time series over the period 1984-2013, our results show very different change patterns in the TWS among these three basins. There is an unprecedented reduction of TWS (-9.8 km&lt;sup&gt;3&lt;/sup&gt;) in the Selenga basin, but remarkable increases (14.4 km&lt;sup&gt;3&lt;/sup&gt; and 13.1 km&lt;sup&gt;3&lt;/sup&gt;) in the Lena-Tabaga and Aldan basins, respectively. The diverse changes in TWS, runoff and precipitation over each basin suggest different hydrologic response mechanisms to permafrost degradation under a warming climate. The Selenga, dominated by lateral degradation (i.e., decreasing permafrost extent), suffers severe water loss via deep infiltration of water that was previously stored close to the surface, which induces a drier surface and subsurface drainage system. In contrast, in the Aldan basin, determined by vertical degradation, thicker active layers develop which sustain a water-rich surface and subsurface environment. In the Lena-Tabaga basin finally, which is characterized by both lateral and vertical degradations, the further development of lateral degradation has led to a stronger increase in groundwater storage in comparison to surface runoff during the increased precipitation states, suggesting a potentially groundwater-dominated hydrologic system in this basin. Our findings are of great importance for the regional water management in permafrost-affected regions under ongoing warming.&lt;/p&gt;

Clinicopathological Features of Advanced Gastric Cancers which Were Misjudged and Subjected to Endoscopic Submucosal Dissection

Background and Aims. Endoscopic submucosal dissection (ESD) is widely performed for early gastric cancer (EGC). We have sometimes encountered gastric cancer lesions for which ESD was performed and at which pathologically advanced cancer was found. In this study, we performed clinicopathological examination of lesions whose endoscopic diagnosis and pathology differed substantially. Methods. ESD was performed for 2,194 gastric cancer lesions (1,753 cases) in our institute from April 2005 through March 2015. The vertical margin was positive or status unknown in 51 lesions (2.3%); among these, muscularis propria (MP) or deeper infiltration was identified in 6 lesions from specimens obtained during subsequent surgery. In 1 lesion with MP invasion, the vertical margin was negative. We evaluated the clinicopathological features of these 7 lesions and retrospectively reviewed endoscopic indicators of submucosal invasion for EGC on white light imaging (WLI), narrow-band imaging magnifying endoscopy (NBI-ME), and endoscopic ultrasonography (EUS) performed previously. Results. Average age was 73.2±7.2 years, and all cases were men. The 7 lesions diagnosed as advanced cancer were 0.32% of 2,194 lesions and were all located in the U region (fundus). On retrospective review of endoscopic findings, 2 of 7 lesions on WBI, 3 of 6 lesions on NBI-ME, and 2 of 5 lesions on EUS met the criteria for indicating submucosal invasion of EGC. No lesions had findings on all 3 modalities. Conclusion. In rare cases, advanced gastric cancer could not be accurately diagnosed by endoscopy using various modalities. Each case had special characteristics making identification of deep infiltration difficult.