Determination of Water Quality Characteristics and Nutrient Exchange Flux at the Sediment–Water Interface of the Yitong River in Changchun City, China

In this paper, the characteristics of water pollution in Yitong River were analyzed by the comprehensive pollution index method. Combined with the pore water concentration gradient method and Fick’s first law, the release characteristics of nutrients at the sediment–water interface of Yitong River (Jilin Province, China) were studied. The results showed that the distribution trend of nitrogen and phosphorus content in the overlying and interstitial water of the Yitong River was the same, and the highest values appeared at the S3 and S5 points in the urban section. The water quality was mainly affected by nitrogen pollutants in domestic sewage. The evaluation results of the water quality comprehensive pollution index showed that the pollution degree of interstitial water in urban areas was much higher than that of the overlying water, and the endogenous nitrogen and phosphorus pollutants had the risk of diffusion to the overlying water. The exchange flux analysis of ammonia nitrogen (NH4+-N), total dissolved nitrogen (TDN), and total dissolved phosphorus (TDP) in water showed that the diffusion flux of NH4+-N ranged from 0.03 to 6.52 mg·(m2·d)−1, and the sediment was the “source” of ammonia nitrogen pollutants. The range of TDN diffusion flux was −1.57 to 11.6 mg·(m2·d) −1, and the difference between points was large. The sediment was both the “source” and “sink” of nitrogen pollutants. The range of TDP diffusion flux was −0.05 to 0.22 mg·(m2·d) −1. Except for point S8, the TDP diffused from sediment into the water body. Among all the sampling points, the diffusion fluxes of NH4+-N, TDN, and TDP at the S3 point were the largest, the release rate of endogenous pollutants was the most rapid, and the pollution to the water quality was the most serious. The results are of great significance to the exchange flux of nutrients at the sediment–water interface of rivers and the prevention and control of water eutrophication. It also provides a reference for the study of nutrient exchange flux at the sediment–water interface of rivers and other surface water bodies worldwide.

Exploration of glassy state in Prussian blue analogues

Prussian blue analogues (PBAs), a class of microporous crystalline coordination frameworks, are long known for their diverse properties in porosity, magnetic, charge transport, catalysis, optics, and more. Versatile structural composition and the ability to control defect ordering through synthetic conditions offer opportunities to manipulate the functionality in the crystalline state. However, developments in Prussian blue analogues (PBAs) have primarily revolved around the ordered crystalline state, and the glassy state of PBAs has not yet been explored. Here we report the discovery of a disordered glassy state of the PBA via mechanically induced crystal–glass transformation. We found the preservation of metal–ligand–metal connectivity, confirming the short-range order and semiconductor behaviour, exhibiting an electronic conductivity value of 0.31 mS cm−1 at 50 ˚C. Mechanical-induced glass transformation also triggers changes in electronic states, where electroneutrality is compensated by introducing unconventional CN− vacancies. Partial disorders and ligand vacancies in recrystallized PBA give rise to an enhanced porosity, inaccessible in the crystalline parent. The present work also established a correlation between the mechanical stress required to initiate crystal–glass transformation and intrinsic mechanical properties, which are controlled by the vacancy/defect content, the presence of interstitial water, and the overall composition of PBAs.

Aether, Fields & Energy Dynamics in Living Bodies - Part II

In this article, we examine dynamics of the three primary aether modalities in the water-body: first, the magnetic, which takes origin in the cardiovascular system; secondly, the radiant, related to ambient light-fall upon the body from the outside or that generated internally, and flows as organized currents in interstitial water; and the dielectric, which predominates in the intracellular fluid spaces, mediated by ion currents, and is involved in the generation and maintenance of cell structure and molecular energy metabolism.

Synthesis and crystal structure of the lanthanum cyanurate complex La[H2N3C3O3]3 · 8.5 H2O

Single crystals of La[H2N3C3O3]3 · 8.5 H2O were obtained from stoichiometric amounts of as-precipitated La(OH)3 with cyanuric acid (CYA) [H3N3C3O3]3 in a boiling aqueous solution, followed by slow cooling and evaporation of water under ambient conditions. According to the X-ray structure analysis of the colorless and transparent crystals, La[H2N3C3O3]3 · 8.5 H2O adopts the triclinic space group P1 (no. 1) and exhibits the unit-cell parameters a = 987.24(7), b = 1110.97(8), c = 1179.81(9) pm, α = 113.716(2), β = 97.053(2), γ = 101.502(2)° for Z = 2. The CYA is singly deprotonated to give monoanions [H2N3C3O3]– which are O,N-coordinated to the La3+ cations. These dihdrogencyanurate anions are assembled in ribbons with two crystallographically different La3+ cations coordinating to either one or two different ligands, respectively. The coordination sphere of the La3+ cations is comprised of water molecules, and interstitial water molecules fill the dead volume of the crystals. The anionic ribbons are stacked to maximize the contact between the six-membered rings, showing distances of about 330 pm.

Blood Cerebrospinal Fluid Barrier Function Disturbance can be Followed by β-amyloid Accumulation

Background: Elucidation of the mechanism of β-amyloid accumulation plays an important role in therapeutic strategies for Alzheimer’s disease (AD). To elucidate the relationship between the function of the blood cerebrospinal fluid barrier (BCSFB) and the production and clearance of β-amyloid, we analyzed the changes in interstitial water flow into the CSF space from the cortex and β-amyloid accumulation in the cortex by using both [15O]H2O and [18F]flutemetamol PET over a 2-year follow-up period. Methods: Twenty-five normal older adult volunteers (13 males and 12 females, 60–81 years old) participated in this 2-year follow-up PET study. Water dynamics were analyzed using two indices in [15O]H2O PET, the influx ratio (IR) and drain rate (DR), and β-amyloid accumulation was assessed qualitatively by [18F]flutemetamol PET. Results: [15O]H2O PET examinations conducted initially and after 2 years showed no significant changes in both indices over the 2-year period (IR: 1.03 ± 0.21 and 1.02 ± 0.20, DR: 1.74 ± 0.43 and 1.67 ± 0.47, respectively). In [18F]flutemetamol PET, on the other hand, one of the 25 participants showed positive results and two showed positive changes after 2 years. In these three participants, the two indices of water dynamics showed low values at both periods (IR: 0.60 ± 0.15 and 0.60 ± 0.13, DR: 1.24 ± 0.12 and 1.11 ± 0.10). Conclusions: Our results indicated that BCSFB function disturbances could be followed by β-amyloid accumulation, because the reduced interstitial flow preceded amyloid accumulation in the positive-change subjects, and amyloid accumulation was not observed in the older adults with sufficiently high values for the two indices. In other words, adequate interstitial flow can potentially prevent amyloid accumulation. The current study confirms that disturbances in the proper clearance of β-amyloid by interstitial flow through the Virchow–Robin spaces into the CSF can play a significant role in senile plaque formation and ultimately the pathogenesis of AD. We believe that further elucidation of interstitial water flow will be the key to developing therapeutic strategies for AD, especially with regard to prevention.Trial registration: UMIN, UMIN000011939. Registered 1November 2013 - Retrospectively registered, http://www.umin.ac.jp/ctr/index.htm

Storage and export of microbial biomass across the western Greenland Ice Sheet

The Greenland Ice Sheet harbours a wealth of microbial life, yet the total biomass stored or exported from its surface to downstream environments is unconstrained. Here, we quantify microbial abundance and cellular biomass flux within the near-surface weathering crust photic zone of the western sector of the ice sheet. Using groundwater techniques, we demonstrate that interstitial water flow is slow (~10−2 m d−1), while flow cytometry enumeration reveals this pathway delivers 5 × 108 cells m−2 d−1 to supraglacial streams, equivalent to a carbon flux up to 250 g km−2 d−1. We infer that cellular carbon accumulation in the weathering crust exceeds fluvial export, promoting biomass sequestration, enhanced carbon cycling, and biological albedo reduction. We estimate that up to 37 kg km−2 of cellular carbon is flushed from the weathering crust environment of the western Greenland Ice Sheet each summer, providing an appreciable flux to support heterotrophs and methanogenesis at the bed.

Structural Transitions and Stability of FAPbI3 and MAPbI3: The Role of Interstitial Water

We studied the influence of water on the structural stability and transformations of MAPI and FAPI by anelastic and dielectric spectroscopies under various temperature and H2O partial pressure protocols. Before discussing the new results in terms of interstitial water in MAPI and FAPI, the literature is briefly reviewed, in search of other studies and evidences on interstitial water in hybrid halide perovskites. In hydrated MAPI, the elastic anomaly between the cubic α and tetragonal β phases may be depressed by more than 50%, demonstrating that there are H2O molecules dispersed in the perovskite lattice in interstitial form, that hinder the long range tilting of the PbI6 octahedra. Instead, in FAPI, interstitial water accelerates in both senses the reconstructive transformations between 3D α and 1D δ phases, which is useful during the crystallization of the α phase. On the other hand, the interstitial H2O molecules increase the effective size of the MA and FA cations to which are bonded, shifting the thermodynamic equilibrium from the compact perovskite structure to the open δ and hydrated phases of loosely bonded chains of PbI6 octahedra. For this reason, when fabricating devices based on hybrid metal-organic halide perovskites, it is important to reduce the content of interstitial water as much as possible before encapsulation.

Dilated perivascular space is related to reduced free-water in surrounding white matter among healthy adults and elderlies but not in patients with severe cerebral small vessel disease

Perivascular space facilitates cerebral interstitial water clearance. However, it is unclear how dilated perivascular space (dPVS) affects the interstitial water of surrounding white matter. We aimed to determine the presence and extent of changes in normal-appearing white matter water components around dPVS in different populations. Twenty healthy elderly subjects and 15 elderly subjects with severe cerebral small vessel disease (CSVD, with lacunar infarction 6 months before the scan) were included in our study. And other 28 healthy adult subjects were enrolled under a different scanning parameter to see if the results are comparable. The normal-appearing white matter around dPVS was categorized into 10 layers (1 mm thickness each) based on their distance to dPVS. We evaluated the mean isotropic-diffusing water volume fraction in each layer. We discovered a significantly reduced free-water content in the layers closely adjacent to the dPVS in the healthy elderlies. however, this reduction around dPVS was weaker in the CSVD subjects. We also discovered an elevated free-water content within dPVS. DPVS played different roles in healthy subjects or CSVD subjects. The reduced water content around dPVS in healthy subjects suggests these MR-visible PVSs are not always related to the stagnation of fluid.