Cation Exchange in Colloidal Transition Metal Nitride Nanocrystals.

Transition metal nitride (TMN)-based nanostructures have emerged as promising materials for diverse applications in electronics, photonics, energy storage, and catalysis due to their highly desirable physicochemical properties. However, synthesizing TMN-based nanostructures with designed compositions and morphologies poses challenges, especially in the solution phase. The cation exchange reaction (CER) stands out as a versatile postsynthetic strategy for preparing nanostructures that are otherwise inaccessible through direct synthesis. Nevertheless, exploration of the CER in TMNs lags behind that in metal chalcogenides and metal phosphides. Here, we demonstrate cation exchange in colloidal metal nitride nanocrystals, employing Cu3N nanocrystals as starting materials to synthesize Ni4N and CoN nanocrystals. By controlling the reaction conditions, Cu3N@Ni4N and Cu3N@CoN core@shell heterostructures with tunable compositions can also be obtained. The Ni4N and CoN nanocrystals are evaluated as catalysts for the electrochemical oxygen evolution reaction (OER). Remarkably, CoN nanocrystals demonstrate superior OER performance with a low overpotential of 286 mV at 10 mA·cm-2, a small Tafel slope of 89 mV·dec-1, and long-term stability. Our CER approach in colloidal TMNs offers a new strategy for preparing other metal nitride nanocrystals and their heterostructures, paving the way for prospective applications.

Screening of Intermetallic Compounds Based on Intermediate Adsorption Equilibrium for Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate (NO3-) reduction reaction (NO3RR) holds great potential for the conversion of NO3- contaminants into valuable NH3 in a sustainable method. Unfortunately, the nonequilibrium adsorption of intermediates and sluggish multielectron transfer have detrimental impacts on the electrocatalytic performance of the NO3RR, posing obstacles to its practical application. Herein, we initially screen the adsorption energies of three key intermediates, i.e., *NO3, *NO, and *H2O, along with the d-band centers on 21 types of transition metal (IIIV and IB)-Sb/Bi-based intermetallic compounds (IMCs) as electrocatalysts. The results reveal that hexagonal CoSb IMCs possess the optimal adsorption equilibrium for key intermediates and exhibit outstanding electrocatalytic NO3RR performance with a Faradaic efficiency of 96.3%, a NH3 selectivity of 89.1%, and excellent stability, surpassing the majority of recently reported NO3RR electrocatalysts. Moreover, the integration of CoSb IMCs/C into a novel Zn-NO3- battery results in a high power density of 11.88 mW cm-2.

Heterophase Intermetallic Compounds for Electrocatalytic Hydrogen Production at Industrial-Scale Current Densities.

Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.

Bi-Functional Electrolyte Additive Leading to a Highly Reversible and Stable Zinc Anode.

A stable stripping/plating process of the zinc anode is extremely critical for the practical application of aqueous zinc metal batteries. However, obstacles, including parasitic reactions and dendrite growth, notoriously deteriorate the stability and reversibility of zinc anode. Herein, Methyl l-α-aspartyl-l-phenylalaninate (Aspartame) is proposed as an effective additive in the ZnSO4 system to realize high stability and reversibility. Aspartame molecule with rich polar functional groups successfully participates in the solvation sheath of Zn2+ to suppress water-induced side reactions. The self-driven adsorption of Aspartame on zinc anode improves uniform deposition with a dose of 10 mm. These synergetic functions endow the zinc anode with a significantly long cycling lifespan of 4500 h. The cell coupled with a vanadium-based cathode also exhibited a high-capacity retention of 71.8% after 1000 cycles, outperforming the additive-free counterparts.

Enhancing Nitrate Reduction to Ammonia Through Crystal Phase Engineering: Unveiling the Hydrogen Bonding Effect in δ-FeOOH Electrocatalysis.

Crystal phase engineering has emerged as a powerful tool for tailoring the electrocatalytic performance, yet its impact on nitrate reduction to ammonia (NRA) remains largely uncharted territory. Herein, density functional theory (DFT) calculations are performed to unravel the influence of the crystal phase of FeOOH on the adsorption behavior of *NO3. Inspiringly, FeOOH samples with four distinct crystal phases (δ, γ, α, and ß) are successfully synthesized and deployed as electrocatalysts for NRA. Remarkably, among all FeOOH samples, δ-FeOOH demonstrates the superior NRA performance, achieving a NH3 Faradic efficiency ( FE NH 3 $\rm{FE} _ {\rm{NH_3}}$ ) of 90.2% at -1.0 V versus reversible hydrogen electrode (RHE) and a NH3 yield rate ( Yield NH 3 $\rm{Yield} _ {\rm{NH_3}}$ ) of 5.73 mg h-1 cm-2 at -1.2 V. In-depth experiments and theoretical calculations unveil the existence of hydrogen bonding interaction between δ-FeOOH and *NOx, which not only enhances the adsorption of *NOx but also disrupts the linear relationships between the free energy of *NO3 adsorption and various parameters, including limiting potential, d-band center (εd) and transferred charge from FeOOH to *NO3, ultimately contributing to the exceptional NRA performance.

D-ribose metabolic disorder and diabetes mellitus.

D-ribose, an ubiquitous pentose compound found in all living cells, serves as a vital constituent of numerous essential biomolecules, including RNA, nucleotides, and riboflavin. It plays a crucial role in various fundamental life processes. Within the cellular milieu, exogenously supplied D-ribose can undergo phosphorylation to yield ribose-5-phosphate (R-5-P). This R-5-P compound serves a dual purpose: it not only contributes to adenosine triphosphate (ATP) production through the nonoxidative phase of the pentose phosphate pathway (PPP) but also participates in nucleotide synthesis. Consequently, D-ribose is employed both as a therapeutic agent for enhancing cardiac function in heart failure patients and as a remedy for post-exercise fatigue. Nevertheless, recent clinical studies have suggested a potential link between D-ribose metabolic disturbances and type 2 diabetes mellitus (T2DM) along with its associated complications. Additionally, certain in vitro experiments have indicated that exogenous D-ribose exposure could trigger apoptosis in specific cell lines. This article comprehensively reviews the current advancements in D-ribose's digestion, absorption, transmembrane transport, intracellular metabolic pathways, impact on cellular behaviour, and elevated levels in diabetes mellitus. It also identifies areas requiring further investigation.

New Insight into Quantity-Dependent Self-Assembly Pattern of Light Levitating Droplet Clusters.

It has been reported that the self-assembly pattern of light levitating droplet clusters above the hot gas-liquid interface is dependent on the quantity of droplets. However, the already-reported theoretical explanation of the quantity-dependent self-assembly pattern cannot work well when the quantity of the light levitating droplet exceeds 15. Herein, we propose a new theoretical perspective to understand the self-assembly of a light levitating droplet cluster by referring to the classical densest packing problem of identical rigid circles in a larger circle with the introduction of the minimum total potential energy principle. Amazingly, the theoretical results obtained by this new approach agree well with experimental results, even though the quantity of the light levitating droplet is up to 142. This study deepens our understanding of the quantity-dependent self-assembly pattern of the light levitating droplet clusters and provides significant inspiration for other analogous self-assembly phenomena.

Nomogram for predicting live birth in ovulatory women undergoing frozen-thawed embryo transfer.

BACKGROUND: Study objectives included the development of a practical nomogram for predicting live birth following frozen-thawed embryo transfers in ovulatory women. METHODS: Totally, 2884 patients with regular menstrual cycles in our center were retrospectively enrolled. In an 8:2 ratio, we randomly assigned patients to training and validation cohorts. Then we identified risk factors by multivariate logistic regression and constructed nomogram. Finally, receiver operating characteristic curve analysis, calibration curve and decision curve analysis were performed to assess the calibration and discriminative ability of the nomogram. RESULTS: We identified five variables which were related to live birth, including age, anti-Müllerian hormone (AMH), protocol of frozen-thawed embryo transfer (FET), stage of embryos and amount of high-quality embryos. We then constructed nomograms that predict the probabilities of live birth by using those five parameters. Receiver operating characteristic curve analysis (ROC) showed that the area under the curve (AUC) for live birth was 0.666 (95% CI: 0.644-0.688) in the training cohort. The AUC in the subsequent validation cohorts was 0.669 (95% CI, 0.625-0.713). The clinical practicability of this nomogram was demonstrated through calibration curve analysis and decision curve analysis. CONCLUSIONS: Our nomogram provides a visual and simple tool in predicting live birth in ovulatory women who received FET. It could also provide advice and guidance for physicians and patients on decision-making during the FET procedure.

Association between preoperative sarcopenia and prognosis of pancreatic cancer after curative-intent surgery: a updated systematic review and meta-analysis.

BACKGROUND: Sarcopenia is associated with poor outcomes in many malignancies. However, the relationship between sarcopenia and the prognosis of pancreatic cancer has not been well understood. The aim of this meta-analysis was to identify the prognostic value of preoperative sarcopenia in patients with pancreatic cancer after curative-intent surgery. METHODS: Database from PubMed, Embase, and Web of Science were searched from its inception to July 2023. The primary outcomes were overall survival (OS), progression-free survival (PFS), and the incidence of major complications. The hazard ratio (HR), odds ratio (OR), and 95% confidence intervals (CIs) were used to assess the relationship between preoperative sarcopenia and the prognosis of patients with pancreatic cancer. All statistical analyses were conducted by Review Manager 5.3 and STATA 17.0 software. RESULTS: A total of 23 retrospective studies involving 5888 patients were included in this meta-analysis. The pooled results demonstrated that sarcopenia was significantly associated with worse OS (HR = 1.53, P < 0.00001) and PFS (HR = 1.55, P < 0.00001). However, this association was not obvious in regard to the incidence of major complications (OR = 1.33, P = 0.11). CONCLUSION: Preoperative sarcopenia was preliminarily proved to be associated with the terrible prognosis of pancreatic cancer after surgery. However, this relationship needs to be further validated in more prospective studies.

EHDPP induces proliferation inhibition and apoptosis to spermatocyte: Insights from transcriptomic and metabolomic profiles.

BACKGROUND: 2-ethylhexyldiphenyl phosphate (EHDPP) was used widespread in recent years and it was reported to impair reproductive behaviors and decrease fertility in male Japanese medaka. However, whether EHDPP causes spermatogenesis disturbance remains uncertain. OBJECTIVES: We aimed to study the male reproductive toxicity of EHDPP and its related mechanism. METHODS: Human spermatocyte cell line GC-2 was treated with 10 µM, 50 µM or 100 µM EHDPP for 24 h. Male CD-1 mice aged 6 weeks were given 1, 10, or 100 mg/kg/d EHDPP daily for 42 days and then euthanized to detect sperm count and motility. Proliferation, apoptosis, oxidative stress was detected in mice and cell lines. Metabolome and transcriptome were used to detect the related mechanism. Finally, anti-oxidative reagent N-Acetylcysteine was used to detect whether it could reverse the side-effect of EHDPP both in vivo and in vitro. RESULTS: Our results showed that EHDPP inhibited proliferation and induced apoptosis in mice testes and spermatocyte cell line GC-2. Metabolome and transcriptome showed that nucleotide metabolism disturbance and DNA damage was potentially involved in EHDPP-induced reproductive toxicity. Finally, we found that excessive ROS production caused DNA damage and mitochondrial dysfunction; NAC supplement reversed the side effects of EHDPP such as DNA damage, proliferation inhibition, apoptosis and decline in sperm motility. CONCLUSION: ROS-evoked DNA damage and nucleotide metabolism disturbance mediates EHDPP-induced germ cell proliferation inhibition and apoptosis, which finally induced decline of sperm motility.

N-acetylcysteine alleviated tris(2-chloroisopropyl) phosphate-induced sperm motility decline and functional dysfunction in mice through reversing oxidative stress and DNA damage.

The decline in male fertility caused by environmental pollutants has attracted worldwide attention nowadays. Tris(2-chloroisopropyl) phosphate (TCPP) is a chlorine-containing organophosphorus flame retardant applied in many consumer products and has multiple side effects on health. However, whether TCPP impairs spermatogenesis remains unclear. In this study, we found that TCPP reduced the sperm motility and blastocyst formation, inhibited proliferation and induced apoptosis in mice testes and spermatocyte cell line GC-2. Moreover, TCPP induced imbalance of oxidant and anti-oxidant, DNA damage and mitochondrial dysfunction, thus induced abnormal spermatogenesis. In this process, p53 signaling pathway was activated and N-acetylcysteine treatment partially alleviated the side effects of TCPP, including decrease of sperm motility, activation of p53 signaling pathway and DNA damage. Finally, our study verified that TCPP elevated reactive oxygen species (ROS), decreased mitochondrial membrane potential and induced apoptosis in human semen samples. Overall, ROS mediated TCPP-induced germ cell proliferation inhibition and apoptosis, which finally led to the decline of sperm motility.

A high-order time-delay difference estimation method for signal enhancement in the distorted towed hydrophone array.

In passive sonar systems, deviations from an ideal linear configuration can significantly impair the beamforming performance of towed hydrophone arrays. This paper presents a method aimed at improving the underwater acoustic signals in the presence of array distortion. The method is centered on a high-order time-delay difference estimation technique utilizing time-frequency autofocus. Initially, a detailed signal model is established that captures the distinctive characteristics of distorted arrays. Subsequently, an algorithm is introduced for high-order time-delay difference estimation to enhance signal fidelity by leveraging phase information within narrowband components originating from incidental acoustic sources. Additionally, a quality metric to evaluate these components is introduced, facilitating the practical implementation of the method. The effectiveness of the proposed approach is validated through both simulation and experimental results, demonstrating its superiority over existing techniques. Importantly, this method does not require prior knowledge of the distortion pattern, making it adaptable to various non-linear array configurations.

I3--Mediated Oxygen Evolution Activities to Boost Rechargeable Zinc-Air Battery Performance with Low Charging Voltage and Long Cycling Life.

An effective strategy to facilitate oxygen redox chemistry in metal-air batteries is to introduce a redox mediator into the liquid electrolyte. The rational utilization of redox mediators to accelerate the charging kinetics while ensuring the long lifetime of alkaline Zn-air batteries is challenging. Here, we apply commercial acetylene black catalysts to achieve an I3--mediated Zn-air battery by using ZnI2 additives that provide I3- to accelerate the cathodic redox chemistry and regulate the uniform deposition of Zn2+ on the anode. The Zn-air battery performs an ultra-long cycle life of over 600 h at 5 mA cm-2 with a final charge voltage of 1.87 V. We demonstrate that I- mainly generates I3- on the surface of carbon catalysts during the electrochemically charging process, which can further chemically react with OH- to generate oxygen and further revert to I-, thus obtaining a stable electrochemical system. This work offers a strategy to simultaneously improve the cycling life and reduce the charging voltage of Zn-air batteries through redox mediator methods.

Transition Metal-Gallium Intermetallic Compounds with Tailored Active Site Configurations for Electrochemical Ammonia Synthesis.

Gallium (Ga) with a low melting point can serve as a unique metallic solvent in the synthesis of intermetallic compounds (IMCs). The negative formation enthalpy of transition metal-Ga IMCs endows them with high catalytic stability. Meanwhile, their tunable crystal structures offer the possibility to tailor the configurations of active sites to meet the requirements for specific catalytic applications. Herein, we present a general method for preparing a range of transition metal-Ga IMCs, including Co-Ga, Ni-Ga, Pt-Ga, Pd-Ga, and Rh-Ga IMCs. The structurally ordered CoGa IMCs with body-centered cubic (bcc) structure are uniformly dispersed on the nitrogen-doped reduced graphene oxide substrate (O-CoGa/NG) and deliver outstanding nitrate reduction reaction (NO3RR) performance, making them excellent catalysts to construct highly efficient rechargeable Zn-NO3 - battery. Operando studies and theoretical simulations demonstrate that the electron-rich environments around the Co atoms enhance the adsorption strength of *NO3 intermediate and simultaneously suppress the formation of hydrogen, thus improving the NO3RR activity and selectivity.

Effects of d-ribose on human erythrocytes: Non-enzymatic glycation of hemoglobin, eryptosis, oxidative stress and energy metabolism.

d-Ribose is not only an important component of some biomacromolecules, but also an active pentose with strong reducibility and non-enzymatic glycation ability. Previous studies reported the diverse role of d-ribose in different cells. In this study, the effects of d-ribose on non-enzymatic glycation of hemoglobin (Hb), as well as eryptosis, oxidative stress and energy metabolism of erythrocytes were observed by molecular fluorescence spectrophotometry, multi-wavelength spectrophotometry, high-pressure liquid chromatography (HPLC), mass spectrometry (MS) and flow cytometer. The results showed that d-ribose had the strongest non-enzymatic glycation ability to Hb in vitro when compared with other monosaccharides, and could enter the erythrocytes in a concentration-dependent manner, which was not inhibited by the specific glucose transporter 1 (GLUT1) inhibitor WZB117. In addition, d-ribose incubation increased the HbA1c, hemolysis, eryptosis, and ROS level of erythrocytes significantly more than that of d-glucose, however, no changes were observed in the levels of ATP, NADPH, and other intermediate energy metabolites in d-ribose treatment. Therefore, the strong non-enzymatic glycation ability of d-ribose may play an important role in erythrocyte damage.

Plasmon-driven methanol oxidation on PtAg nanoalloys prepared by improved pulsed laser deposition.

The methanol oxidation reaction (MOR) is crucial in many energy-conversion devices. Although intensive efforts have been devoted to improving the MOR catalytic activity of Pt-based catalysts by treatment or alloying, enhancing the MOR catalyst performance utilizing solar energy has been less investigated. PtAg nanoalloys, combining the intrinsic catalytic activity of Pt toward the MOR with the visible spectrum plasmonic response of Ag, are expected to be a good MOR catalyst for solar energy, however, it remains challenging to incorporate these immiscible elements into a nanoalloy in a controlled way using conventional synthetic techniques. Herein, we proposed a general strategy for alloying silver and platinum elements into single-phase solid-solution nanoparticles with arbitrarily desired composition by bonding pure Pt targets with pure Ag strips in an improved pulsed laser deposition. The as-prepared PtAg nanoalloys show two crystalline phases and an average particle size of about 4 nm. To prove utility, we use the PtAg nanoalloys as support-free MOR catalysts anchored on the surface of a glassy carbon electrode solidly and uniformly. The PtAg nanoalloys exhibit a mass catalytic activity of 3.6 A mg-1, which is 4.5 times higher than that of the commercial Pt/C catalyst. Besides, the PtAg nanoalloys exhibit a promising regenerability after reactivation by cyclic voltammetry. Furthermore, the MOR catalytic activity of PtAg nanoalloys increased by 16% under irradiation by simulated sunlight, which is attributed to the surface plasmon resonance as ascertained from the UV-vis absorption spectra and photocurrent response experiments. These studies are believed to provide a new strategy for the enhancement of MOR catalytic activity with visible light as the driving force.

Fast and accurate wideband sparse spatial spectrum estimation in an underwater strong interference environment.

Wideband sparse spatial spectrum estimation is an important direction-of-arrival (DOA) estimation method that can obtain a high resolution with few snapshots and a low signal-to-noise ratio. However, in an underwater strong interference environment, the accuracy of DOA estimation may be seriously affected, and even the weak targets could be completely masked. In this paper, we propose a fast matrix filter design method based on truncated nuclear norm regularization to attenuate strong interferences while passing weak targets. The matrix filter operator and the exact covariance matrix after filtering can be obtained simultaneously by solving a convex optimization problem that contains the output power term and non-Toeplitz error propagation control term. Then the modified sparse spectrum fitting algorithm based on the matrix filter is used to estimate spatial spectrum over closely spaced wideband signals. Compared with existing methods, the proposed method achieves higher DOA estimation accuracy and lower computational time for matrix filter design. Meanwhile, the estimation accuracy of the proposed method is verified with the experimental results.

[Analysis of Residual Post-Resection Electrocorticography Status and Related Risk Factors in Patients With Medically Intractable Epilepsytractable Epilepsy].

Objective: To analyze the residual post-resection electrocorticography (ECoG) status and the related risk factors in patients with medically intractable epilepsy (MIE). Methods: A retrospective analysis was conducted to cover 146 MIE patients who underwent craniotomy for surgical resection in the department of Neurosurgery, Second Affiliated Hospital of Chengdu Medical College between January 2006 and January 2018. The patients were divided into a non-residual group ( n=54) and a residual group ( n=92) according to their ECoG results after the first resection surgery. Then, the 92 patients in the residual group underwent additional palliative surgery and they were further divided into an improvement subgroup ( n=50) and a non-improvement subgroup ( n=42), according to the reevaluation results of improvements in their postoperative ECoG. The differences in the mean annual seizure-free rate among the groups were compared. Univariate and multivariate logistic regression analysis was conducted to analyze the risk factors of residual post-resection ECoG. Results: During the ten-year follow-up after the operation, the mean annual seizure-free rate was 86.7% in the non-residual group and 57.1% in the residual group, showing significant difference between the two groups ( P<0.001). In the subgroups, the mean annual seizure-free rate was 71% in the improvement subgroup and 46.5% in the non-improved subgroup, showing significant difference between the two subgroups ( P=0.003). Logistic regression showed that risk factors associated with residual post-resection ECoG included being female, patient age at the time of surgery being over 18, multi-lobe epilepsy, functional area involvement, and negative MRI findings ( P<0.05). Analysis of the subgroups showed that multi-lobe epilepsy and functional area involvement were risk factors related to not showing improvements in post-resection ECoG ( P<0.05). Conclusions: Findings based on the status of residual post-resection ECoG have shown that patients without residual post-resection ECoG had the best treatment outcomes, and patients who had residual post-resection ECoG, but showed significant improvement after palliative surgery had the second best treatment outcomes. Patients who were female, who had their surgeries when they were older than 18, and who had multi-lobe epilepsy, functional area involvement, or negative MRI results were more likely to have residual post-resection ECoG. Among patients with residual post-resection ECoG, those with multi-lobe epilepsy and functional area involvement showed little improvement in residual post-resection ECoG even after undergoing additional palliative surgery.

Isolated Electron-Rich Ruthenium Atoms in Intermetallic Compounds for Boosting Electrochemical Nitric Oxide Reduction to Ammonia.

The direct electrochemical nitric oxide reduction reaction (NORR) is an attractive technique for converting NO into NH3 with low power consumption under ambient conditions. Optimizing the electronic structure of the active sites can greatly improve the performance of electrocatalysts. Herein, we prepare body-centered cubic RuGa intermetallic compounds (i.e., bcc RuGa IMCs) via a substrate-anchored thermal annealing method. The electrocatalyst exhibits a remarkable NH4 + yield rate of 320.6 µmol h-1 mg-1 Ru with the corresponding Faradaic efficiency of 72.3 % at very low potential of -0.2 V vs. reversible hydrogen electrode (RHE) in neutral media. Theoretical calculations reveal that the electron-rich Ru atoms in bcc RuGa IMCs facilitate the adsorption and activation of *HNO intermediate. Hence, the energy barrier of the potential-determining step in NORR could be greatly reduced.

Evaluation of proton transport and solvation effect in hydrated Nafion membrane with degradation.

In proton exchange membrane fuel cells (PEMFCs), free radicals easily attack ionomers, resulting in membrane degradation. In this work, the multistate empirical valence bond (MS-EVB) method is employed to investigate the chemical degradation impact of Nafion membranes on proton transport and the solvation effect. The hydrophilic domain and its connectivity are analyzed. The numbers of surrounding water and hydronium ions as well as the location of the solvation shell are evaluated. The results demonstrate that the membrane degradation does not change the interaction with the hydronium ions and water molecules but alters the coordination number, leading to a larger hydrophilic domain and a poorer connectivity. The acid groups and protons are distributed more at the edge of the hydrophilic region to accelerate the proton motion, which is not conducive to the proton transport along the membrane side chain.