Development of a ReaxFF Reactive Force Field for Pt/Cl Systems with Application to Platinum Metal Etching with Chlorine and Hydrogen Chloride Gases.

In this study, we present the development of a ReaxFF Pt/Cl/H reactive force field designed to elucidate the etching process by Cl for Pt surfaces. The ReaxFF force field parameters were optimized based on a quantum mechanical training set, which included adsorption energies of Cl and dissociation of HCl on Pt(100) and Pt(111) surfaces, energy/volume relations of PtCl2 crystals, and Cl diffusion on Pt(100) and Pt(111) surfaces. The predictive capability of the force field was further established through molecular dynamics simulations, which investigated the interactions of Cl2 and HCl molecules with the (100) and (111) surfaces of c-Pt crystalline solid slabs. A comparative analysis revealed that the Pt (100) surface exhibited higher susceptibility to chlorination and etching, leading to a more dominant removal of surface Pt atoms, whereas the Pt (111) surface showed greater resistance to these processes. This resistance impeded the access of Cl atoms to the Pt surface, resulting in a slower formation of PtxCly molecules. The etching ratios between HCl and Cl2 were compared with experimental results, yielding satisfactory agreement. This indicates that the developed ReaxFF protocol serves as a valuable tool for studying atomistic-scale details of the etching process in platinum metal systems.

Stable metal anodes enabled by a labile organic molecule bonded to a reduced graphene oxide aerogel.

Metallic anodes (lithium, sodium, and zinc) are attractive for rechargeable battery technologies but are plagued by an unfavorable metal-electrolyte interface that leads to nonuniform metal deposition and an unstable solid-electrolyte interphase (SEI). Here we report the use of electrochemically labile molecules to regulate the electrochemical interface and guide even lithium deposition and a stable SEI. The molecule, benzenesulfonyl fluoride, was bonded to the surface of a reduced graphene oxide aerogel. During metal deposition, this labile molecule not only generates a metal-coordinating benzenesulfonate anion that guides homogeneous metal deposition but also contributes lithium fluoride to the SEI to improve Li surface passivation. Consequently, high-efficiency lithium deposition with a low nucleation overpotential was achieved at a high current density of 6.0 mA cm-2 A Li|LiCoO2 cell had a capacity retention of 85.3% after 400 cycles, and the cell also tolerated low-temperature (-10 °C) operation without additional capacity fading. This strategy was applied to sodium and zinc anodes as well.

Atomistic level aqueous dissolution dynamics of NASICON-Type Li1+xAlxTi2-x(PO4)3 (LATP).

Advancing the atomistic level understanding of aqueous dissolution of multicomponent materials is essential. We combined ReaxFF and experiments to investigate the dissolution at the Li1+xAlxTi2-x(PO4)3-water interface. We demonstrate that surface dissolution is a sequentially dynamic process. The phosphate dissolution destabilizes the NASICON structure, which triggers a titanium-rich secondary phase formation.

Constant and intermittent hypoxia modulates immunity, oxidative status, and blood components of red seabream and increases its susceptibility to the acute toxicity of red tide dinoflagellate.

Hypoxia is an increasing threat to aquatic ecosystems and its impact on economically and ecologically important marine fish species needs to be studied. Especially, the consequences of hypoxia when occurring along with harmful algal blooms (HABs) are currently not well documented. In this study, we investigated the effect of constant and intermittent (daily and weekly) hypoxia on respiration, immunity, hematological parameters, and oxidative status of red seabream for 2, 4, and 6 weeks. Under constant and daily intermittent hypoxia, respiration rate significantly increased in 2 weeks compared to the control. Constant and daily intermittent hypoxia caused significant decreases in the activity of alternative complement pathway, lysozyme, and the level of total immunoglobulin (Ig), as well as significant increases in the concentrations of cortisol, hemoglobin, red blood cells, and white blood cells. A significantly higher level of malondialdehyde was measured for all hypoxia-exposed groups, indicating lipid peroxidation and oxidative stress. At 4 and 6 week, the level of glutathione and enzymatic activities of glutathione reductase and glutathione peroxidase were significantly decreased after constant and daily intermittent hypoxia challenge. The enzymatic activities of superoxide dismutase and catalase were significantly increased at 2 and 4 weeks, but they were decreased after 6 weeks by constant and daily intermittent hypoxia. Constant and daily intermittent hypoxia with subsequent non-toxin producing dinoflagellate Cochlodinium polykrikoides treatment significantly reduced the respiration rate in 3 and 24 h exposure and survival rate of red seabream. Taken together, the red seabream can be vulnerable to HABs under hypoxia condition through inhibition of immunity and antioxidant defense ability. Our findings are helpful in better understanding of molecular and physiological effects of hypoxia, which can be used in aquaculture and fisheries management.

ReaxFF molecular dynamics simulations of electrolyte-water systems at supercritical temperature.

We have performed ReaxFF molecular dynamics simulations of alkali metal-chlorine pairs in different water densities at supercritical temperature (700 K) to elucidate the structural and dynamical properties of the system. The radial distribution function and the angular distribution function explain the inter-ionic structural and orientational arrangements of atoms during the simulation. The coordination number of water molecules in the solvation shell of ions increases with an increase in the radius of ions. We find that the self-diffusion coefficient of metal ions increases with a decrease in density under supercritical conditions due to the formation of voids within the system. The hydrogen bond dynamics has been interpreted by the residence time distribution of various ions, which shows Li+ having the highest water retaining capability. The void distribution within the system has been analyzed by using the Voronoi polyhedra algorithm providing an estimation of void formation within the system at high temperatures. We observe the formation of salt clusters of Na+ and K+ at low densities due to the loss of dielectric constants of ions. The diffusion of ions gets altered dramatically due to the formation of voids and nucleation of ions in the system.

A ReaxFF molecular dynamics study of molecular-level interactions during binder jetting 3D-printing.

In the present work, we study one of the major additive manufacturing processes, i.e., the binder jetting printing (BJP) process, at the molecular level through atomistic-scale level representations of powders and binder solutions with chromium-oxide (Cr-oxide) nanoparticles and water-based diethylene glycol solutions, respectively. The results show that both diethylene glycol and water contribute to the bonding of Cr-oxide particles during the print and curing stages by forming a hydrogen bond network. Heating the system to the burn-out temperature results in the oxidation of diethylene glycol and the decomposition of the hydrogen bond network. Subsequently, Cr-oxide particles are partially sintered by forming Cr-O bonds. The final sintering facilitates further Cr-O bond formation. Additionally, the influence of the chemical composition of the binder solution is investigated by performing ReaxFF molecular dynamics simulations on two sets of systems, which control the number of water and diethylene glycol molecules, respectively. Our results demonstrate that adding both diethylene glycol and water to the binder solution can raise the number of "useful" hydrogen bonds, resulting in a higher breaking strength at the print and curing stages. During the burn-out and sintering stages, the influence of water on the breaking strength is not obvious. In contrast, an optimal quantity of binder species exists for the breaking strength after sintering. A comparison of the ReaxFF molecular dynamics simulations using 2-ethoxyethanol, diethylene glycol and 1-(2,2,2-trihydroxyethoxy)ethane-2,2,2-triol as the binder phase indicates that an increasing number of hydroxyl groups leads to higher breaking strength at the print and curing stages. The findings from this study can be extended to identify the optimal binder chemistry, curing and sintering conditions for different material systems.

Development of the ReaxFF Methodology for Electrolyte-Water Systems.

A new ReaxFF reactive force field has been developed for water-electrolyte systems including cations Li+, Na+, K+, and Cs+ and anions F-, Cl-, and I-. The reactive force field parameters have been trained against quantum mechanical (QM) calculations related to water binding energies, hydration energies and energies of proton transfer. The new force field has been validated by applying it to molecular dynamics (MD) simulations of the ionization of different electrolytes in water and comparison of the results with experimental observations and thermodynamics. Radial distribution functions (RDF) determined for most of the atom pairs (cation or anion with oxygen and hydrogen of water) show a good agreement with the RDF values obtained from DFT calculations. On the basis of the applied force field, the ReaxFF simulations have described the diffusion constants for water and electrolyte ions in alkali metal hydroxide and chloride salt solutions as a function of composition and electrolyte concentration. The obtained results open opportunities to advance ReaxFF methodology to a wide range of applications involving electrolyte ions and solutions.

Predictive Factors of Retear in Patients With Repaired Rotator Cuff Tear on Shoulder MRI.

OBJECTIVE: This study aimed to find independent prognostic factors related to retear of the rotator cuff tendon in patients with repaired full-thickness supraspinatus tendon tear by evaluation of pre- and postoperative MR images. MATERIALS AND METHODS: Shoulder MR images were retrospectively analyzed for 83 patients who had undergone arthroscopic or open rotator cuff repair with acromioplasty for full-thickness supraspinatus tendon tear from April 2014 to March 2015. On preoperative MR images, the type of rotator cuff tear, extent of retraction of torn tendon, anteroposterior (AP) dimension of torn tendon, signal intensity of tear edge, degree of fat infiltration in supraspinatus and infraspinatus muscles, and acromiohumeral interval (AHI) were assessed. Postoperative cuff integrity seen on MR images was classified into five categories according to the Sugaya classification system, and patients were categorized into retear or intact groups. Factors assessed on preoperative MR images were compared between the two groups. RESULTS: The overall retear rate was 57.8%. Significant differences were observed between the retear and intact groups in terms of the mean values of the extent of tendon retraction (20.4 vs 11.7 mm), AP dimension of the tear (16.1 vs 11.4 mm), AHI (6.8 vs 8.7 mm), and degree of fat infiltration of the supraspinatus and infraspinatus muscles (for the supraspinatus muscle, 3, 30, and 15 patients in the retear group vs 5, 27, and three patients in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively; for the infraspinatus muscle, 27, 12, and 9 patients in the retear group vs 29, 5, and one patient in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively). Multivariable analysis revealed that AHI and degree of tendon retraction were independent predictive factors affecting retear of rotator cuff after repair. CONCLUSION: The retear rate of repaired rotator cuff tendon was about 57.8%. Independent prognostic factors of retear were degree of tendon retraction and AHI on preoperative MR images.

Development of a ReaxFF reactive force field for lithium ion conducting solid electrolyte Li1+xAlxTi2-x(PO4)3 (LATP).

We developed a ReaxFF reactive force field for NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) materials, which is a promising solid-electrolyte that may enable all-solid-state lithium-ion batteries. The force field parameters were optimized based on density functional theory (DFT) data, including equations of state and the heats of formation of ternary metal oxides and metal phosphate crystal phases (e.g., LixTiO2, Al2TiO5, LiAlO2, AlPO4, Li3PO4 and LiTi2(PO4)3 (LTP)), and the energy barriers for Li diffusion in TiO2 and LTP via vacancies and interstitial sites. Using ReaxFF, the structural and the energetic features of LATP were described properly across various compositions - Li occupies more preferentially the interstitial site next to Al than next to Ti. Also, as observed in experimental data, the lattice parameters decrease when Ti is partly substituted by Al because of the smaller size of the Al cation. Using this force field, the diffusion mechanism and the ionic conductivity of Li in LTP and LATP were investigated at T = 300-1100 K. Low ionic conductivity (5.9 × 10-5 S cm-1 at 300 K) was obtained in LTP as previously reported. In LATP at x = 0.2, the ionic conductivity was slightly improved (8.4 × 10-5 S cm-1), but it is still below the experimental value, which is on the order of 10-4 to 10-3 S cm-1 at x = 0.3-0.5. At higher x (higher Al composition), LATP has a configurational diversity due to the Al substitution and the concomitant insertion of Li. By performing a hybrid MC/MD simulation for LATP at x = 0.5, a thermodynamically stable LATP configuration was obtained. The ionic conductivity of this LATP configuration was calculated to be 7.4 × 10-4 S cm-1 at 300 K, which is one order of magnitude higher than the ionic conductivity for LTP and LATP at x = 0.2. This value is in good agreement with our experimental value (2.5 × 10-4 S cm-1 at 300 K) and the literature values. The composition-dependent ionic conductivity of LATP was successfully demonstrated using the ReaxFF reactive force field, verifying the applicability of the LATP force field for the understanding of Li diffusion and the design of highly Li ion conductive solid electrolytes. Furthermore, our results also demonstrate the feasibility of the MC/MD method in modeling LATP configuration, and provide compelling evidence for the solid solution sensitivity on ionic conductivity.

Activation of Oxygen and Hydrogen Peroxide by Copper(II) Coupled with Hydroxylamine for Oxidation of Organic Contaminants.

This study reports that the combination of Cu(II) with hydroxylamine (HA) (referred to herein as Cu(II)/HA system) in situ generates H2O2 by reducing dissolved oxygen, subsequently producing reactive oxidants through the reaction of Cu(I) with H2O2. The external supply of H2O2 to the Cu(II)/HA system (i.e., the Cu(II)/H2O2/HA system) was found to further enhance the production of reactive oxidants. Both the Cu(II)/HA and Cu(II)/H2O2/HA systems effectively oxidized benzoate (BA) at pH between 4 and 8, yielding a hydroxylated product, p-hydroxybenzoate (pHBA). The addition of a radical scavenger, tert-butyl alcohol, inhibited the BA oxidation in both systems. However, electron paramagnetic resonance (EPR) spectroscopy analysis indicated that (•)OH was not produced under either acidic or neutral pH conditions, suggesting that the alternative oxidant, cupryl ion (Cu(III)), is likely a dominant oxidant.

Development of a ReaxFF Reactive Force Field for the Pt-Ni Alloy Catalyst.

We developed the ReaxFF force field for Pt/Ni/C/H/O interactions, specifically targeted for heterogeneous catalysis application of the Pt-Ni alloy. The force field is trained using the DFT data for equations of state of Pt3Ni, PtNi3 and PtNi alloys, the surface energy of the PtxNi1-x(111) (x = 0.67-0.83), and binding energies of various atomic and molecular species (O, H, C, CH, CH2, CH3, CO, OH, and H2O) on these surfaces. The ReaxFF force field shows a Pt surface segregation at x ≥ 0.67 for the (111) surface and x ≥ 0.62 for the (100) surface in vacuum. In addition, from the investigation of the preferential alloy component of the adsorbates, it is expected that H and CH3 on the alloy surface to induce a segregation of Pt whereas the oxidation intermediates and products such as C, O, OH, H2O, CO, CH, and CH2 are found to induce Ni segregation. The relative order of binding strengths among adsorbates is a function of alloy composition and the force field is trained to describe the trend observed in DFT calculations, namely, H2 < H2O < CH3 ≈ O2 ≈ CO < OH < CH2 < C ≈ CH on Pt8Ni4, H2 < H2O < CO ≈ O2 < CH3 < OH < CH2 < CH < C on Pt9Ni3, and H2 < H2O < O2 < CO < CH3 < OH < CH2 < C ≈ CH on Pt10Ni2. Using this force field, we performed the grand-canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations for a Pt3Ni slab and a truncated cuboctahedral nanoparticle terminated by (111) and (100) faces, to examine the surface segregation trend under different gas environments. It is found that Pt segregates to the alloy surface when the surface is exposed to vacuum and/or H2 environment while Ni segregates under the O2 environment. These results suggest that the Pt/Ni alloy force field can be successfully used for the preparation of Pt-Ni nanobimetallic catalysts structure using GCMC and run MD simulations to investigate its role and the catalytic chemistry in catalytic oxidation, dehydrogenation and coupling reactions. The current Pt/Ni force field still is found to have difficulties in describing the observed segregation trend in Ni-rich alloy compositions (x < 0.6), suggesting the need for additional force field training and evaluation for its application to describe the characteristics and chemistry of Ni-rich alloys.

The kinetoplastid parasite Azumiobodo hoyamushi, the causative agent of soft tunic syndrome of the sea squirt Halocynthia roretzi, resides in the East Sea of Korea.

Mass mortality of the edible sea squirt Halocynthia roretzi since the 1990s in the southern and eastern seas of Korea has caused large economic losses. The disease is characterized by symptoms of initially softened and thinned tunics that eventually rupture. Thus, the disease is called soft tunic syndrome (STS); however, the causative agent in these regions is unknown. In the present study, two kinetoplastid organisms were isolated from STS sea squirts collected from culture farms in Tongyeong located in the East Sea of Korea. Phylogenetic analysis of 18S rRNA sequences identified these organisms as Azumiobodo hoyamushi and Procryptobia sorokini. These kinetoplastids were injected into healthy sea squirts and cultured at 15°C for 13days. Sea squirts injected with A. hoyamushi showed 100% STS whereas, P. sorokini did not induce disease, thereby confirming A. hoyamushi as the causative agent of STS. A. hoyamushi flourishes in vitro at 10-15°C, and dies at temperatures below 5°C or above 20°C. The optimum salinity level for growth is 30-35psu, and death occurs below 25psu. These optima coincide with marine temperature and salinity levels between March and June on the southern coasts of Korea, the period when the syndrome occurs at the highest frequency. The identification here of A. hoyamushi as the causative agent of STS and our findings regarding its optimum growth conditions should lead to methods for reducing the incidence of STS.

Development of loop-mediated isothermal amplification targeting 18s ribosomal DNA for rapid detection of Azumiobodo hoyamushi (Kinetoplastea).

Ascidian soft tunic syndrome (AsSTS) caused by Azumiobodo hoyamushi (A. hoyamushi) is a serious aquaculture problem that results in mass mortality of ascidians. Accordingly, the early and accurate detection of A. hoyamushi would contribute substantially to disease management and prevention of transmission. Recently, the loop-mediated isothermal amplification (LAMP) method was adopted for clinical diagnosis of a range of infectious diseases. Here, the authors describe a rapid and efficient LAMP-based method targeting the 18S rDNA gene for detection of A. hoyamushi using ascidian DNA for the diagnosis of AsSTS. A. hoyamushi LAMP assay amplified the DNA of 0.01 parasites per reaction and detected A. hoyamushi in 10 ng of ascidian DNA. To validate A. hoyamushi 18S rDNA LAMP assays, AsSTS-suspected and non-diseased ascidians were examined by microscopy, PCR, and by using the LAMP assay. When PCR was used as a gold standard, the LAMP assay showed good agreement in terms of sensitivity, positive predictive value (PPV), and negative predictive value (NPV). In the present study, a LAMP assay based on directly heat-treated samples was found to be as efficient as DNA extraction using a commercial kit for detecting A. hoyamushi. Taken together, this study shows the devised A. hoyamushi LAMP assay could be used to diagnose AsSTS in a straightforward, sensitive, and specific manner, that it could be used for forecasting, surveillance, and quarantine of AsSTS.

Exploring the conformational and reactive dynamics of biomolecules in solution using an extended version of the glycine reactive force field.

In order to describe possible reaction mechanisms involving amino acids, and the evolution of the protonation state of amino acid side chains in solution, a reactive force field (ReaxFF-based description) for peptide and protein simulations has been developed as an expansion of the previously reported glycine parameters. This expansion consists of adding to the training set more than five hundred molecular systems, including all the amino acids and some short peptide structures, which have been investigated by means of quantum mechanical calculations. The performance of this ReaxFF protein force field on a relatively short time scale (500 ps) is validated by comparison with classical non-reactive simulations and experimental data of well characterized test cases, comprising capped amino acids, peptides, and small proteins, and reaction mechanisms connected to the pharmaceutical sector. A good agreement of ReaxFF predicted conformations and kinetics with reference data is obtained.

Transcriptional activity and expression of liver X receptor in the ascidian Halocynthia roretzi.

Liver X receptors, LXRs, are ligand-activated transcription factors that belong to the group H nuclear receptor (NR) superfamily. In this study, an LXR (HrLXR) cDNA was cloned from the ascidian Halocynthia roretzi hepatopancreas and characterized to examine the functional conservation of ancestral LXRs in chordates. A phylogenetic analysis of HrLXR showed that it belongs to the tunicate (urochordate) LXR subgroup, which is distinct from vertebrate LXRs. Quantitative real-time PCR analysis revealed that HrLXR mRNA was expressed predominantly in the gills, and highly expressed in unfertilized eggs followed by decrease at later embryonic and larval stages. Unexpectedly, HrLXR was not activated by GW3965, whereas a synthetic ligand for a farnesoid X receptor, GW4064, activated HrLXR. This activation was abolished by the deletion of 51 amino acids from the N-terminus. In a mammalian two-hybrid system, HrLXR interacted with HrRXR in the presence of GW4064 or 9-cis retinoic acid. The injection of GW3965 and GW4064 in vivo increased the ATPbinding cassette sub-family G member 4 and HrLXR mRNA levels in the hepatopancreas and gills. These results suggest that the mRNA expression and transcriptional properties of HrLXR are different from those of vertebrate LXRs, although HrLXR is likely responsive to the related NR ligand, GW4064.

Aqueous Stability of Metal-Organic Frameworks Using ReaxFF-Based Metadynamics Simulations.

Aqueous stability is a critical property for the application of metal-organic framework (MOF) materials in humid conditions. The sampling of the free energy surface for a water reaction is challenging due to a lack of a reactive force field. Here, we developed a ReaxFF force field for simulating the reaction of zeolitic imidazole frameworks (ZIFs) with water. We carried out metadynamics simulations based on ReaxFF to study the reaction of water with a few different types of MOFs. We also conducted an experimental water immersion test and characterized the XRD, TG, and gas adsorption properties of the MOFs before and after the immersion test. By considering the energy barrier for a hydrolysis reaction, the simulation results are in good agreement with the experiments. MOFs with open structures and large pores are found to be unstable in metadynamics simulations, where the water molecule can attack or bond with the metallic node relatively easily. In contrast, it is more difficult for water to attack the Zn atom in the ZnN4 tetrahedral structure of ZIFs. We also found that ZIFs with the -NO2 functional groups have higher water stability. Discrepancies between the metadynamics simulation and gas adsorption experiments have been accounted for from the phase/crystallinity change of the structure reflected in the X-ray diffraction and thermogravimetry analysis of the MOF samples.

Aqueous phase conversion of CO2 into acetic acid over thermally transformed MIL-88B catalyst.

Sustainable production of acetic acid is a high priority due to its high global manufacturing capacity and numerous applications. Currently, it is predominantly synthesized via carbonylation of methanol, in which both the reactants are fossil-derived. Carbon dioxide transformation into acetic acid is highly desirable to achieve net zero carbon emissions, but significant challenges remain to achieve this efficiently. Herein, we report a heterogeneous catalyst, thermally transformed MIL-88B with Fe0 and Fe3O4 dual active sites, for highly selective acetic acid formation via methanol hydrocarboxylation. ReaxFF molecular simulation, and X-ray characterisation results show a thermally transformed MIL-88B catalyst consisting of highly dispersed Fe0/Fe(II)-oxide nanoparticles in a carbonaceous matrix. This efficient catalyst showed a high acetic acid yield (590.1 mmol/gcat.L) with 81.7% selectivity at 150 °C in the aqueous phase using LiI as a co-catalyst. Here we present a plausible reaction pathway for acetic acid formation reaction via a formic acid intermediate. No significant difference in acetic acid yield and selectivity were noticed during the catalyst recycling study up to five cycles. This work is scalable and industrially relevant for carbon dioxide utilisation to reduce carbon emissions, especially when green methanol and green hydrogen are readily available in future.

Correction: Self-limiting stoichiometry in SnSe thin films.

Correction for 'Self-limiting stoichiometry in SnSe thin films' by Jonathan R. Chin et al., Nanoscale, 2023, 15, 9973-9984, https://doi.org/10.1039/D3NR00645J.

Oxidative Stress and DNA Damage in Pagrus major by the Dinoflagellate Karenia mikimotoi.

Karenia mikimotoi is a common species of red tide dinoflagellate that causes the mass mortality of marine fauna in coastal waters of Republic of Korea. Despite continuous studies on the ecophysiology and toxicity of K. mikimotoi, the underlying molecular mechanisms remain poorly understood. Red sea bream, Pagrus major, is a high-value aquaculture fish species, and the coastal aquaculture industry of red sea bream has been increasingly affected by red tides. To investigate the potential oxidative effects of K. mikimotoi on P. major and the molecular mechanisms involved, we exposed the fish to varying concentrations of K. mikimotoi and evaluated its toxicity. Our results showed that exposure to K. mikimotoi led to an accumulation of reactive oxygen species (ROS) and oxidative DNA damage in the gill tissue of P. major. Furthermore, we found that K. mikimotoi induced the activation of antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, in the gill tissue of P. major, with a significant increase in activity at concentrations above 5000 cells/mL. However, the activity of glutathione S-transferase did not significantly increase at the equivalent concentration. Our study confirms that oxidative stress and DNA damage is induced by acute exposure to K. mikimotoi, as it produces ROS and hypoxic conditions in P. major. In addition, it was confirmed that gill and blood samples can be used as biomarkers to detect the degree of oxidative stress in fish. These findings have important implications for the aquaculture of red sea bream, particularly in the face of red tide disasters.

Self-limiting stoichiometry in SnSe thin films.

Unique functionalities can arise when 2D materials are scaled down near the monolayer limit. However, in 2D materials with strong van der Waals bonds between layers, such as SnSe, maintaining stoichiometry while limiting vertical growth is difficult. Here, we describe how self-limiting stoichiometry can promote the growth of SnSe thin films deposited by molecular beam epitaxy. The Pnma phase of SnSe was stabilized over a broad range of Sn : Se flux ratios from 1 : 1 to 1 : 5. Changing the flux ratio does not affect the film stoichiometry, but influences the predominant crystallographic orientation. ReaxFF molecular dynamics (MD) simulation demonstrates that, while a mixture of Sn/Se stoichiometries forms initially, SnSe stabilizes as the cluster size evolves. The MD results further show that the excess selenium coalesces into Se clusters that weakly interact with the surface of the SnSe particles, leading to the limited stoichiometric change. Raman spectroscopy corroborates this model showing the initial formation of SnSe2 transitioning into SnSe as experimental film growth progresses. Transmission electron microscopy measurements taken on films deposited with growth rates above 0.25 Å s-1 show a thin layer of SnSe2 that disrupts the crystallographic orientation of the SnSe films. Therefore, using the conditions for self-limiting SnSe growth while avoiding the formation of SnSe2 was found to increase the lateral scale of the SnSe layers. Overall, self-limiting stoichiometry provides a promising avenue for maintaining growth of large lateral-scale SnSe for device fabrication.