ConspectusWater appears simple, yet its anomalous behavior reveals an unexpected structural complexity. A growing body of evidence indicates that many of water's anomalies arise from fluctuations between low-density (LD) and high-density (HD) local structural motifs, a form of polymorphism that is well established in the supercooled regime and increasingly supported at ambient conditions. Yet, how these structural motifs manifest within hydration layers, where water interacts with nanoparticles, proteins, and charged interfaces, remains far less understood. This interfacial water governs colloidal stability, biomolecular function, and chemical reactivity, but its microscopic organization is difficult to probe directly with conventional bulk techniques.In this Account, we describe how luminescence nanothermometry provides a powerful and versatile approach to accessing density fluctuations in the hydration layer. By monitoring temperature-dependent optical and Brownian observables of luminescent probes, structural reorganizations of the surrounding hydration layer can be inferred with nanoscale sensitivity. Over the past several years, our group has shown that lanthanide-doped upconversion nanoparticles (UCNPs) and fluorescent proteins, such as enhanced green fluorescent protein (EGFP), act as local reporters of hydration-water density fluctuations.A central observation emerging from these studies is the existence of a crossover temperature, Tc, at which hydration-water observables exhibit bilinear temperature dependencies. This Tc correlates with the depletion of LD motifs in the hydration shell and typically falls within the 315-330 K range, close to the minimum of water's isothermal compressibility. Importantly, Tc depends on the nature of the probe and its interaction with the surrounding water.By systematically varying nanoparticle size, pH, surface chemistry, and probe type, we show that previously contradictory trends in Tc can be unified by a single parameter: the effective surface charge density of the probe. When Tc is plotted against this quantity, data from UCNPs with different sizes and surface functionalizations, as well as from fluorescent proteins at different concentrations, collapse onto a master curve. This result demonstrates that interfacial electrostatics govern the stability of LD motifs in the hydration layer, providing a physically intuitive framework that links nanoscale charge distributions to local water structure.We further extend this framework by examining nuclear quantum effects through isotopic substitution. Using EGFP as a model biomolecular probe, we show that replacing H2O with D2O shifts Tc upward by ≈10 K and enhances protein thermal stability, consistent with stronger hydrogen bonding and the displacement of thermodynamic anomalies in heavy water. In contrast, several inorganic and molecular probes fail to resolve a comparable isotopic shift, highlighting that the detectability of LD/HD fluctuations might be probe-dependent. Control experiments in H218O confirm that hydrogen, rather than oxygen, dominates these quantum effects.Together, these results establish luminescent nanoprobes as sensitive reporters of hydration-water density fluctuations and reveal how interfacial charge, confinement, and quantum effects sculpt water structure at the nanoscale. Beyond resolving long-standing questions about water's anomalies, this approach opens new avenues for understanding protein stability, designing functional nanomaterials, and exploiting hydration-water density fluctuations in chemical and biological systems.

Protocol to measure protein half-life in cell culture using heavy water.

This work presents the neutron-induced transmutation of long-lived fission products (LLFPs) in an accelerator-driven transmuter (ADT) that is not loaded with any nuclear fuel and therefore is free of fission reactions producing additional fission products. The ADT couples a 1-GeV and 30-mA proton accelerator to a blanket made of LLFP rods immersed in heavy water moderator, coolant, and reflector. The proton beam impinges against a lead-bismuth windowless target and produces, on average, ~29 neutrons per incident proton by a spallation reaction. The heavy water moderator slows down the spallation neutrons to enhance the transmutation of LLFP isotopes by higher neutron capture cross sections at thermal energies. Argonne National Laboratory has been actively working on the design of the linac proton accelerator. At present, no software can directly model the fixed-source transmutation of LLFPs from a spallation reaction; therefore, this work externally couples MCNP and FISPACT codes using a Python script. At the beginning of each burnup step, MCNP simulates proton, pion, neutron, gamma, and electron transport and tallies the neutron flux in 12 burnable material regions with 1102 energy groups. Then, FISPACT simulates the fixed-source transmutation using MCNP output data. At the end of the burnup step, burnable materials are shuffled to maximize the transmutation of the LLFPs.

Electrochemical hydrogen isotope separation has been constrained for decades by the similar energy barriers of the rate-determining O-H and O-D bond cleavage step in water isotopologues. Herein, we compact H-bond connectivity through screening a series of additives to stimulate electrochemical proton quantum tunneling (QT) behaviors of "through-barrier", which are virtually impossible for heavier D-relevant motions. The average H-bond length of H2O⋯OH- is 3.4% shorter (2.78 Å) with isopropanol additive at the engineered interface. Fundamentally, QT effects are magnified by selectively promoting proton transfer-involved reactions through strengthening the H-bond and filling the H-bond gap, which are further proved by both experimental Arrhenius plots with near small-curvature tunneling approximation and a stronger proton excursion in path integral molecular dynamics simulations. Hence, a record-high H2O separation factor of 276 is realized at room temperature with a three-order-of-magnitude growth of H/D kinetic isotope effect constant up to 10,165. Significantly, a large-scale multistage reactor is engineered to obtain continuous enrichment of heavy water with a deuterium atomic fraction over 80%.

Iron (Fe) contamination in Indonesian waters frequently exceeds the drinking water quality standard (0.3 mg/L) and poses risks to human health and aquatic ecosystems, highlighting the need for a selective and effective removal method. This study aimed to analyze the effect of solution concentration on the adsorption capacity of an EDTA-based Ion Imprinted Polymer (IIP) for Fe(III) ions. The research employed an experimental design through the synthesis of IIP using the precipitation polymerization method, with methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and benzoyl peroxide (BPO) as the initiator. Data were collected through characterization using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX), while Fe(III) concentrations were measured using Atomic Absorption Spectrophotometry (AAS). Fe(NO₃)₃ solutions at concentrations ranging from 5 to 35 ppm were tested at neutral pH. Data analysis was conducted by calculating the adsorption capacity as the difference between the initial and final concentrations. The results showed that increasing the initial concentration increased adsorption capacity until equilibrium was reached, with a maximum of 19.06 mg/g. FTIR analysis confirmed the presence of characteristic functional groups and the removal of Fe–O bonds after extraction, while SEM analysis revealed the formation of specific cavities in the IIP structure. In conclusion, the synthesized IIP demonstrates good selectivity and effectiveness for Fe(III) adsorption from aqueous solutions, indicating its potential application as a selective adsorbent for heavy metal-contaminated water treatment.

Measurement of the turnover rate of proteins, different metabolites and lipids in living organisms is important for the understanding of biochemical pathways and physiology studies. Such experiments can be performed by administering isotopically labeled substances (food or water) to the organism and measuring the amount of the isotopes in the endogenous compounds. Here, we administered 20% heavy water (D2O) to a guinea pig for 156 days and regularly measured the deuterium uptake in C-H groups in the different compounds of blood, urine and feces using high-resolution mass spectrometry. We successfully measured the time required for reaching the maximum deuteration level for several classes of compounds: 10 days for blood lipids (PC, PE, TAG); 60 days for sterol derivatives, heme B and hemoglobin; and 70 days for stercobilin. Also, for those compounds, we measured the deuterium elimination time from the organism when deuterium administration was stopped. The turnover of lipids was also studied by administering deuterated oat leaves grown at 10% D2O to the guinea pig. The analysis of blood revealed that triglycerides demonstrate the inclusion of the deuterium after 5 h. All experiments were performed on a single guinea pig that remained alive and in good health after all experiments. The current research demonstrates the possibility of using long-term D2O administration for the investigation of metabolism.

This study investigated the corrosion behavior of four structural materials of nuclear reactors, austenitic stainless steel (SUS304), Incoloy 800H, zirconium alloy (Zr-2.5Nb), and carbon steel (SAB106) in 20 mM oxalic acid (OA) at 95°C under static immersion conditions. OA is commonly used in chemical oxidation reduction decontamination for nuclear decommissioning due to its reductive chelation capability. The results indicated that OA induced moderate dissolution, primarily through chelation with Fe2+ /Fe3+ ions, while exhibiting surface passivation tendencies that restrained uncontrolled attack. A weight loss analysis showed the highest mass reduction for SAB106, followed by SUS304, while Incoloy 800H and Zr-2.5Nb exhibited minimal changes. The highest Fe concentration, 258.87 ppm after 9 h, was observed in SAB106. Elemental analysis data confirmed significant oxygen enrichment on SAB106 (39.67%), indicating aggressive oxide formation, whereas SUS304, Incoloy 800H, and Zr-2.5Nb remained comparatively stable. Scanning electron microscopy images revealed pronounced pore formation and intergranular attack in SAB106, while SUS304 retained a smooth morphology with shallow pits. Incoloy 800H and Zr-2.5Nb showed only fine micropores due to its Ni-rich matrix. These results demonstrated that OA induces severe localized corrosion in Fe-dominant alloys, but exerts only mild effects on Ni-Cr alloys, highlighting the compositional dependence of corrosion resistance. The findings provide insights into alloy compatibility during OA-based reductive decontamination processes, particularly for primary coolant components in pressurized heavy water reactor and pressurized water reactor systems.

The higher atomic mass of deuterium basically affects hydrogen-bonding interactions and solvent association, raising critical alarms about the precision of biomolecular measurements executed in heavy water. Herein, we combine linear infrared (IR) spectroscopy, circular dichroism (CD) spectroscopy, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations to explore how solvent isotopic exchange alters protein structure as well as dynamics. Comparative studies of different protonated (H2O, CH3OH) and deuterated (D2O, CD3OD) solvents expose noticeable differences in hydrogen-bond lifetimes, solvation patterns, and protein secondary structural constancy. Particularly, the amide I hydrogen-bonded complex shows suggestively longer lifetimes in D2O than in H2O, reflecting slower hydrogen-bond dynamics and reduced flexibility of the protein backbone. Similar effects are detected in methanol/methanol-d4, also highlighting that these phenomena are not unique to water but are intrinsic to deuterium replacement. These multitechnique results clearly validate that biomolecular structures and dynamical behaviors in deuterated solvents are markedly different from those in their protonated surroundings. Our conclusions extend the understanding of isotope substitution effects in solvation and underscore the necessity for careful interpretation of experimental data acquired in D2O or other deuterated solvents, mainly when concluding native biological conditions.

An electrochemical protocol for the regioselective synthesis of multi-substituted pyridines via a (3+3) annulation is described. The strategy utilizes enamine-iminium cross-coupling to construct the pyridine core with high functional group tolerance under mild reaction conditions. Alongside, C5-deuterated pyridines are achieved in a single step using deuterium oxide as the inexpensive deuterium source. In addition to the electro-redox events, electrogenerated acid (EGA) plays a decisive role in key bond-forming steps. Mechanistic studies, including control experiments and cyclic voltammetry, reveal the involvement of EGA and assist in identifying crucial reaction intermediates. The synthetic utility of the method is showcased by post-annulation derivatization, affording a diverse library of pyridine derivatives.

An energy-intensive multifunction cavitation process incorporating synchrotron X-rays (PXMEI-MFC) was used to treat the surfaces of the single-crystal Ni-based superalloys SC610 and CMSX-4, employing a mixture of water and heavy water. Similar to data previously obtained from PXMEI-MFC processing using a mixture of acetone and deuterated acetone, the efficiency with which SC610 could be modified was improved compared with that obtained using a laser-irradiated MFC process. However, the water/heavy water system provided a limited processing area compared with the acetone/deuterated acetone system and the alloy surface was not flattened. Although no further oxide film was added, the original oxide layer was not removed and the proportion of the γ' phase was not optimized. In addition, the structure-stabilizing elements Ta, W, and Re did not exhibit significant segregation. Nevertheless, the hardness of the processed region was increased to a greater extent than had been obtained in trials with the acetone/deuterated acetone mixture. Because the degree of processing was improved even with a heavy water concentration of just 1%, it is believed that, during processing of the SC610, heavy water produced higher cavitation collapse pressures and temperatures compared with non-deuterated water. In principle, based on adjusting the balance of various energy inputs, mixtures of heavy water and water should also enable optimization of the γ' phase proportion through self-organization and homogenization of the lattice structures of the γ' and γ phases, similar to mixtures of deuterated acetone and acetone.

Abstract The inherent instability and risk of liquefaction associated with unstable glaciomarine clay are both scientifically intriguing and societally important. Stabilizing sensitive soils is increasingly necessary with the unfolding climate crisis, which leads to wilder and wetter weather. The relevant length scales extend from nanometer-sized pores to kilometer-sized geological features. Laboratory experiments are important for gaining a better understanding of these phenomena. Here, we present a study of the ultra-soft sandstone Saltwash South , which essentially consists of quartz particles glued together by clay, as a proxy for nanoscopically fine-grained sensitive soil to facilitate time-resolved imaging of the onset of activation and liquefaction. By employing in situ time-resolved combined X-ray and neutron computed tomography (CT), we visualize the structural deformation caused by the presence of water and salts. While neutron imaging was sensitive to the presence of normal and heavy water, simultaneous X-ray imaging was used to measure the porous structure, swelling, and initial liquefaction response of the consolidated rock. Uniform expansion was observed in regions exposed to water, reflecting clay swelling and disaggregation. In tightly confined samples, the swelling and disaggregation were suppressed. Finally, we discuss future perspectives of this promising approach to studying liquefaction phenomena in porous media.

Influence of D2O substitution on BNCT dosimetry with the AB-BNCT system: A combined Monte Carlo and experimental study.

Study on the adsorption of Cu(Ⅱ) and Pb(Ⅱ) in water by carbon nanotube-loaded biochar.

Nature’s Cleanup Crew: Algal–Bacterial Partnerships in Heavy Metal-Polluted Waters

Functional hydrogels-enabling the gateway for sustainable water treatment and harvesting technologies.

From fluorescent detection to photothermal conversion: Heavy metal water treatment and material upcycling based on biomass ratiometric carbon dots

ABSTRACT This study explored the mediating role of specific environmental beliefs between general environmental beliefs and water consumption behavior in Segambut, Kuala Lumpur. Using 158 responses collected through nonprobability purposive sampling, PLS‐SEM was applied for data analysis. The findings show that ecological and utilitarian beliefs significantly influence water consumption, whereas the human exception paradigm and limits to growth affect both belief systems. Natural balance impacts utilitarian beliefs but not ecological ones. The study highlights the importance of raising awareness to reduce water consumption among heavy water users, suggesting that future conservation campaigns should focus on educating households about sustainable water use.

To assess the feasibility of deuterium-deuterium(D-D) neutron sources for thermal neutron imaging applications, we employed Monte Carlo simulation code PHITS to optimize the moderator-collimator assembly design for a D-D neutron generator. Through systematic parametric studies of layer materials and thicknesses, an optimized multilayer structure was established, comprising a 4 cm natural uranium layer, 6 cm polyethylene moderator, 10 cm heavy water moderator, 20 cm graphite reflector, 5 cm borated polyethylene shield, and 2 cm lead absorber. Simulation results demonstrate that the neutron beam shaped by the optimized assembly achieves a thermal neutron flux of 4.33 × 104 cm-2·s-1 at the imaging plane, with a collimation ratio of 20 and an n/γ ratio of 1.37 × 1011 cm-2·Sv-1. These parameters satisfy the design criteria for thermal neutron imaging applications.

The evaporative decay of mixed heavy and light water clusters was measured. The branching ratios of the three isotopologue molecules scale with the deuterium fraction from cluster size N=9 and up, including across the well-known shell closing at N=21, and are consistent with macroscopic surface values. Differences in the free energies of competing channels derived from the scaled distributions take the simplest possible form of a single energy parameter and the deuterium-protium mixing entropy. The observations here represent a direct observation of the isotopic mixing entropy. The energy parameter is consistent with zero point vibrational energy differences of the free and condensed water molecule for both H_{2}O/HDO and HDO/D_{2}O ratios.

Multitiered duckweed bioreactors have been developed but have limitations due to the weight of the water column. It was hypothesized that fog-o-ponic growth systems can enable space efficient duckweed culturing by facilitating stacked cultivation systems with multiple thin layers of duckweed, in the absence of a heavy water column. In this study, the growth was assessed of Lemna minor suspended on a fabric textile under a nutrient-rich medium provided as a fog. The best growth of L. minor was a relative growth rate (RGR) of 0.24 d−1 with a maximum quantum efficiency (Fv/Fm) and light-adapted quantum yield (Y(II)) of around 0.8 and 0.5, respectively, which are values comparable to those achieved on traditional liquid medium under otherwise similar conditions. These results reveal that L. minor not only survives under fog-o-ponics culture conditions, but it thrives both in short and longer trials. Consistent with good growth, removal of nutrients by L. minor was considerably (e.g.,500 mg total nitrogen (TN) m−2 day−1) under fog-o-ponics conditions. It is concluded the innovative way of duckweed culturing comprises a promising, multi-stacked, high capacity, phytoremediation system.