Berberine alleviates concanavalin A-induced autoimmune hepatitis in mice by modulating the gut microbiota.

BACKGROUND: Autoimmune hepatitis (AIH) is an immune-mediated liver disease of unknown etiology accompanied by intestinal dysbiosis and a damaged intestinal barrier. Berberine (BBR) is a traditional antibacterial medicine that has a variety of pharmacological properties. It has been reported that BBR alleviates AIH, but relevant mechanisms remain to be fully explored. METHODS: BBR was orally administered at doses of 100 mg⋅kg-1⋅d-1 for 7 days to mice before concanavalin A-induced AIH model establishment. Histopathological, immunohistochemical, immunofluorescence, western blotting, ELISA, 16S rRNA analysis, flow cytometry, real-time quantitative PCR, and fecal microbiota transplantation studies were performed to ascertain BBR effects and mechanisms in AIH mice. RESULTS: We found that liver necrosis and apoptosis were decreased upon BBR administration; the levels of serum transaminase, serum lipopolysaccharide, liver proinflammatory factors TNF-α, interferon-γ, IL-1ß, and IL-17A, and the proportion of Th17 cells in spleen cells were all reduced, while the anti-inflammatory factor IL-10 and regulatory T cell proportions were increased. Moreover, BBR treatment increased beneficial and reduced harmful bacteria in the gut. BBR also strengthened ileal barrier function by increasing the expression of the tight junction proteins zonula occludens-1 and occludin, thereby blocking lipopolysaccharide translocation, preventing lipopolysaccharide/toll-like receptor 4 (TLR4)/ NF-κB pathway activation, and inhibiting inflammatory factor production in the liver. Fecal microbiota transplantation from BBR to model mice also showed that BBR potentially alleviated AIH by altering the gut microbiota. CONCLUSIONS: BBR alleviated concanavalin A-induced AIH by modulating the gut microbiota and related immune regulation. These results shed more light on potential BBR therapeutic strategies for AIH.

Simple Molecules under High-Pressure and High-Temperature Conditions: Synthesis and Characterization of α- and ß-C(NH)2 with Fully sp3 -Hybridized Carbon.

The elements hydrogen, carbon, and nitrogen are among the most abundant in the solar system. Still, little is known about the ternary compounds these elements can form under the high-pressure and high-temperature conditions found in the outer planets' interiors. These materials are also of significant research interest since they are predicted to feature many desirable properties such as high thermal conductivity and hardness due to strong covalent bonding networks. In this study, the high-pressure high-temperature reaction behavior of malononitrile H2 C(CN)2 , dicyandiamide (H2 N)2 C=NCN, and melamine (C3 N3 )(NH2 )3 was investigated in laser-heated diamond anvil cells. Two previously unknown compounds, namely α-C(NH)2 and ß-C(NH)2 , have been synthesized and found to have fully sp3 -hybridized carbon atoms. α-C(NH)2 crystallizes in a distorted ß-cristobalite structure, while ß-C(NH)2 is built from previously unknown imide-bridged 2,4,6,8,9,10-hexaazaadamantane units, which form two independent interpenetrating diamond-like networks. Their stability domains and compressibility were studied, for which supporting density functional theory calculations were performed.

Highly-efficient heterojunction solar cells based on 2D Janus transition-metal nitride halide (TNH) monolayers with ultrahigh carrier mobility.

Symmetry breaking has a crucial effect on electronic band structure and subsequently affects the light-absorption coefficient of monolayers. We systematically report a family of two-dimensional (2D) Janus transition-metal nitride halides (TNHs, T = Ti, Zr, Hf, Fe, Pd, Pt, Os, and Re; H = Cl and F) with breaking of both in-plane and out-of-plane structural symmetry. The dynamical, thermal and mechanical stabilities are calculated to check the stability of the Janus TNHs. The electric properties of ten TNHs are studied via the HSE06+SOC method and the band gaps range from 0.93 eV (PdNCl) to 4.74 eV (HfNCl). Desirable light adsorption coefficients of up to 105 cm-1 are obtained for the Janus TNHs with no central symmetry. The Janus OsNCl monolayer shows excellent electrical transport properties and ultrahigh carrier mobility (104 cm2 V-1 s-1). Heterojunctions formed by stacking two Janus TNH monolayers are further investigated for solar cell applications. Eight of the heterojunctions have type-II band alignments. Surprisingly, the OsNCl/FeNCl heterojunction has a power conversion efficiency (PCE) of 23.45%, which is a larger value compared to the PCE of GeSe/SnSe heterostructures (21.47%). The optical properties and the built-in electric field of the OsNCl/FeNCl heterojunction are investigated. These results indicate that the stable Janus TNH monolayers have potential applications in photoelectric devices, and the vertical heterojunctions can be used in solar cells.

Laser-Driven Insulator-Metal Phase Transitions in CsPbI3 Quantum Dots and Influence of Doped Metal Nanowires.

All-inorganic CsPbI3 perovskite quantum dots (QDs) have received extensive attention in developing optoelectronic devices due to their outstanding properties. Here, using time-dependent density functional theory (TDDFT), the optical properties of the three distinct phases (α, γ, and δ) of the CsPbI3 QDs are investigated. Surprisingly, the δ phase structured QDs exhibit stronger optical absorption properties than the α and γ phase QDs when exposed to equivalent laser irradiation. Considering the quantum size effect, size regulation is also performed on the three structures, the results reveal a significant improvement in optical properties as the size increases in the direction of laser irradiation. More interestingly, Ag-hybrid QDs show better optical gain and maintain a laser-driven metallic state. Our results demonstrate the great potential of size adjustment and metal nanowire coupling in improving the optoelectronic properties of QDs and developing efficient photovoltaic devices.

Interlayer electronic coupling regulates the performance of FeN MXenes and Fe2B2 MBenes as high-performance Li- and Al-ion batteries.

When two-dimensional (2D) materials are stacked into van der Waals structures, interlayer electronic coupling can induce excellent properties in energy storage materials. Here, we investigate the interlayer coupling of the FeN/Fe2B2 heterojunction as an anode material, which is constructed using vertically planar FeN and puckered Fe2B2 nanosheets. These structures were searched by the CALYPSO method and computed by density functional theory calculations. The stabilities of the FeN monolayer, Fe2B2 monolayer, and FeN/Fe2B2 heterojunction were tested in terms of dynamics, mechanics, and thermodynamics, respectively. These structures have good performances as anode materials, including the capacities of the FeN (Fe2B2) monolayer of 9207 mA h g-1 (2713 mA h g-1) and 3069 mA h g-1 (1005 mA h g-1) for Al and Li, respectively. The stable FeN/Fe2B2 heterojunction shows extremely low diffusion barriers of 0.01 eV, a high Al ion capacity of 4254 mA h g-1, and relatively low voltages. Hess's law revealed that the interlayer electronic coupling impacts the adsorption process of the FeN layer in the FeN/Fe2B2 heterojunction, which decreases the pz orbital of the N atom for the heterojunction. The unequal distribution of electrons between the layers results in interlayer polarization; the value of interlayer polarization was quantitatively calculated to be 0.64 pC m-1. The presence of adsorbed Li and Al atoms between the layers helps maintain the original structure and prevents the interlayer sliding from damaging the heterojunction. These findings offer insights for understanding the structural and electronic properties of the FeN/Fe2B2 heterojunction, which provides crucial information for rational design and advanced synthesis of novel electrode materials.

A Newly Synbiotic Combination Alleviates Obesity by Modulating the Gut Microbiota-Fat Axis and Inhibiting the Hepatic TLR4/NF-κB Signaling Pathway.

SCOPE: Obesity has been recognized as a worldwide public health crisis, this is accompanied by dysregulation of the intestinal microbiota and upregulation of liver steatosis and adipose inflammation. Synbiotic as a novel alternative therapy for obesity have recently gained much attention. METHODS: This study innovatively research the anti-obesity properties of a newly synbiotic composed of Lactobacillus acidophilus, Bifidobacterium infantis and konjac glucomannan oligosaccharides. RESULTS: The synbiotic treatment can reduce body weight, fat mass, blood sugar, liver steatosis and adipose inflammation in obesity mice fed by high-fat diet (HFD). Meanwhile, synbiotic treatment activated brown adipose tissue and improve energy, glucose and lipid metabolism. In addition, synbiotic treatment not solely enhanced the protection of intestinal barrier, but also ameliorated gut microbiota dysbiosis directly by enhancing beneficial microbes and reducing potentially harmful bacteria. Furthermore, the microbiome phenotype and functional prediction showed that synbiotic treatment can improve the gut microbiota functions involving inflammatory state, immune response, metabolism and pathopoiesia. CONCLUSION: The synbiotic may be an effective candidate treatment strategy for the clinical prevention and treatment of obesity and other associated metabolic diseases such as hyperlipidemia, nonalcoholic fatty liver diseases by alleviating inflammatory response, regulating energy metabolism and maintaining the balance of intestinal microecology.

Hydrogen gas ameliorates acute alcoholic liver injury via anti-inflammatory and antioxidant effects and regulation of intestinal microbiota.

Alcoholic liver disease (ALD) is a globally prevalent liver-related disorder characterized by severe oxidative stress and inflammatory liver damage, for which no effective treatment is currently available. Hydrogen gas (H2) has been demonstrated to be an efficient antioxidant in various diseases in animals as well as humans. However, the protective effects of H2 on ALD and its underlying mechanisms remain to be elucidated. The present study demonstrated that H2 inhalation ameliorated liver injury, and attenuated liver oxidative stress, inflammation, and steatosis in an ALD mouse model. Moreover, H2 inhalation improved gut microbiota, including increasing the abundance of Lachnospiraceae and Clostridia, and decreasing the abundance of Prevotellaceae and Muribaculaceae, and also improved intestinal barrier integrity. Mechanistically, H2 inhalation blocked activation of the LPS/TLR4/NF-κB pathway in liver. Notably, it was further demonstrated that the reshaped gut microbiota may accelerate alcohol metabolism, regulate lipid homeostasis and maintain immune balance by bacterial functional potential prediction (PICRUSt). Fecal microbiota transplantation from mice that had undergone H2 inhalation significantly alleviated acute alcoholic liver injury. In summary, the present study showed that H2 inhalation alleviated liver injury by reducing oxidative stress and inflammation, while also improving intestinal flora and enhancing the intestinal barrier. H2 inhalation may serve as an effective intervention for preventing and treating ALD in a clinical context.

A Novel Synbiotic Alleviates Autoimmune Hepatitis by Modulating the Gut Microbiota-Liver Axis and Inhibiting the Hepatic TLR4/NF-κB/NLRP3 Signaling Pathway.

Autoimmune hepatitis (AIH) is a liver disease characterized by chronic liver inflammation. The intestinal barrier and microbiome play critical roles in AIH progression. AIH treatment remains challenging because first-line drugs have limited efficacy and many side effects. Thus, there is growing interest in developing synbiotic therapies. This study investigated the effects of a novel synbiotic in an AIH mouse model. We found that this synbiotic (Syn) ameliorated liver injury and improved liver function by reducing hepatic inflammation and pyroptosis. The Syn reversed gut dysbiosis, as indicated by an increase in beneficial bacteria (e.g., Rikenella and Alistipes) and a decrease in potentially harmful bacteria (e.g., Escherichia-Shigella) and lipopolysaccharide (LPS)-bearing Gram-negative bacterial levels. The Syn maintained intestinal barrier integrity, reduced LPS, and inhibited the TLR4/NF-κB and NLRP3/Caspase-1 signaling pathway. In addition, microbiome phenotype prediction by BugBase and bacterial functional potential prediction using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) showed that Syn improved gut microbiota function involving inflammatory injury, metabolism, immune response, and pathopoiesia. Furthermore, the new Syn was as effective as prednisone against AIH. Therefore, this novel Syn could be a candidate drug for alleviating AIH through its anti-inflammatory and antipyroptosis properties that relieve endothelial dysfunction and gut dysbiosis. IMPORTANCE Synbiotics can ameliorate liver injury and improve liver function by reducing hepatic inflammation and pyroptosis. Our data indicate that our new Syn not only reverses gut dysbiosis by increasing beneficial bacteria and decreasing lipopolysaccharide (LPS)-bearing Gram-negative bacteria but also maintains intestinal barrier integrity. Thus, its mechanism might be associated with modulating gut microbiota composition and intestinal barrier function by inhibiting the TLR4/NF-κB/NLRP3/pyroptosis signaling pathway in the liver. This Syn is as effective as prednisone in treating AIH without side effects. Based on these findings, this novel Syn represents a potential therapeutic agent for AIH in clinical practice.

The Trichinella spiralis-derived antigens alleviate HFD-induced obesity and inflammation in mice.

Obesity, an increasingly prevalent disease worldwide, is accompanied by chronic inflammation and intestinal dysbiosis. Helminth infections have been increasingly proved to exhibit a protective role in several inflammation-associated diseases. Considering the side effects of live parasite therapy, efforts have been made to develop helminth-derived antigens as promising candidates with fewer adverse effects. This study aimed to evaluate the effect and mechanisms of TsAg (T. spiralis-derived antigens) on obesity and the associated inflammation in high-fat diet (HFD)-fed mice. C57BL/6J mice were fed a normal diet or HFD with or without TsAg treatment. The results reported that TsAg treatment alleviated body weight gain and chronic inflammation induced by HFD. In the adipose tissue, TsAg treatment prevented macrophage infiltration, reduced the expression of Th1-type (IFN-γ) and Th17-type (IL-17A) cytokines while upregulating the production of Th2-type (IL-4) cytokines. Furthermore, TsAg treatment enhanced brown adipose tissue activation and energy and lipid metabolism and reduced intestinal dysbiosis, intestinal barrier permeability and LPS/TLR4 axis inflammation. Finally, the protective role of TsAg against obesity was transmissible via the fecal microbiota transplantation approach. For the first time, our findings showed that TsAg alleviated HFD-induced obesity and inflammation via modulation of the gut microbiota and balancing the immune disorders, suggesting that TsAg might be a safer promising therapeutic strategy for obesity.

A Synbiotic Ameliorates Con A-Induced Autoimmune Hepatitis in Mice through Modulation of Gut Microbiota and Immune Imbalance.

SCOPE: Changes in the intestinal flora are related to autoimmune hepatitis (AIH) development. The aim of this study is to investigate the synergistic effects of probiotics and prebiotics on liver injury induced by concanavalin A (Con A). METHODS AND RESULTS: C57BL/6 mice are fed probiotics (Pro), prebiotics (Pre), synbiotic (Syn) for 7 days and then Con A is injected via tail veins to induce AIH. Additionally, methylprednisolone (MP) is gavaged 0.5 h after the Con A injection. It is found that both Pro, Pre, Syn, and MP decrease the levels of serum transaminase, liver F4/80+ macrophage cells, and hepatocellular apoptosis. Pro, Pre, and Syn decrease proinflammatory cytokines, elevate levels of anti-inflammatory as well as restored immune imbalance in AIH. Besides, Pro, Pre, and Syn not only reshape the perturbed gut microbiota, but also maintain intestinal barrier integrity, block the activation of lipopolysaccharide (LPS)/TLR4/NF-κB pathway in the liver. Interestingly, the effects of Syn are superior to Pro or Pre alone in Con A-induced acute liver injury. CONCLUSIONS: Syn obviously facilitates AIH remission. The combined use of Pro and Pre is effective in improving Pro and Pre efficacy and can be an important tool for preventing and adjuvant treating patients for AIH.

Compound Probiotic Ameliorates Acute Alcoholic Liver Disease in Mice by Modulating Gut Microbiota and Maintaining Intestinal Barrier.

Alcoholic liver disease (ALD) is a worldwide health threaten lack of effective treatment. Gut dysbiosis and concomitant augmented intestinal permeability are strongly implicated in the pathogenesis and progression of ALD. Research on the protective effect of probiotics on ALD is limited, and more effective intestinal microecological regulators and the related mechanisms still need to be further explored. In the present study, the protective effects and mechanisms of a compound probiotic against acute alcohol-induced liver injury in vivo were explod. It was showed that the compound probiotic ameliorated liver injury in acute ALD mice and stabilized the levels of ALT, AST, and TG in serum. The compound probiotic reversed acute alcohol-induced gut dysbiosis and maintained the intestinal barrier integrity by upregulating the production of mucus and the expression of tight junction (TJ) proteins and thus reduced LPS level in liver. Meanwhile, the compound probiotic reduced inflammation level by inhibiting TLR4/NF-κB signaling pathway and suppressed oxidative stress level in liver. Furthermore, the compound probiotic alleviated liver lipid accumulation by regulating fatty acid metabolism-associated genes and AMPK-PPARα signaling pathway. Noteworthy, fecal microbiota transplantation (FMT) realized comparable protective effect with that of compound probiotic. In conclusion, present study demonstrates the beneficial effects and underlying mechanism of the compound probiotic against acute alcohol-induced liver injury. It provides clues for development of novel strategy for treatment of ALD.

Multifunctional PbS2 Monolayer with an In-Plane Negative Poisson Ratio and Photocatalytic Water Splitting Properties.

Designing novel multifunctional materials at the nanoscale is vitally important for flexible electronics. Here, we have uncovered a two-dimensional metal dichalcogenide PbS2 with intriguing negative Poisson ratio behavior and favorable optical and photocatalytic water splitting properties. The calculations indicate that the Poisson ratio of the PbS2 monolayer is -0.061 along both x and y lattice directions, which is attributed to its unique tetrahedral motif and the ligand field of the local PbS4 units in the PbS2 monolayer. The electronic band structures show that the narrow band gap (1.59 eV) of the PbS2 monolayer could be effectively modulated by strain engineering. Most importantly, the strain-induced tunability of optical absorbance and suitable band edge alignment make the PbS2 monolayer a promising catalyst for photocatalytic water splitting, which is further confirmed by the reaction free energies. These findings offer an effective avenue for the design and synthesis of a novel optoelectronic functional material.

Bip-Yorkie interaction determines oncogenic and tumor-suppressive roles of Ire1/Xbp1s activation.

Unfolded protein response (UPR) is the mechanism by which cells control endoplasmic reticulum (ER) protein homeostasis. ER proteostasis is essential to adapt to cell proliferation and regeneration in development and tumorigenesis, but mechanisms linking UPR, growth control, and cancer progression remain unclear. Here, we report that the Ire1/Xbp1s pathway has surprisingly oncogenic and tumor-suppressive roles in a context-dependent manner. Activation of Ire1/Xbp1s up-regulates their downstream target Bip, which sequesters Yorkie (Yki), a Hippo pathway transducer, in the cytoplasm to restrict Yki transcriptional output. This regulation provides an endogenous defensive mechanism in organ size control, intestinal homeostasis, and regeneration. Unexpectedly, Xbp1 ablation promotes tumor overgrowth but suppresses invasiveness in a Drosophila cancer model. Mechanistically, hyperactivated Ire1/Xbp1s signaling in turn induces JNK-dependent developmental and oncogenic cell migration and epithelial-mesenchymal transition (EMT) via repression of Yki. In humans, a negative correlation between XBP1 and YAP (Yki ortholog) target gene expression specifically exists in triple-negative breast cancers (TNBCs), and those with high XBP1 or HSPA5 (Bip ortholog) expression have better clinical outcomes. In human TNBC cell lines and xenograft models, ectopic XBP1s or HSPA5 expression alleviates tumor growth but aggravates cell migration and invasion. These findings uncover a conserved crosstalk between the Ire1/Xbp1s and Hippo signaling pathways under physiological settings, as well as a crucial role of Bip-Yki interaction in tumorigenesis that is shared from Drosophila to humans.

Pressure induced phase transitions of bulk CsGeCl3 and ultrafast laser pulse induced excited-state properties of CsGeCl3 quantum dots.

First-principles calculations are carried out to investigate the structural, electronic, and optical properties of CsGeCl3. The results indicate that CsGeCl3 undergoes three structural phase transitions from Cm or R3m to Pm3̄m at 8.5 GPa, from Pm3̄m to ppPv-Pnma at 9.4 GPa, and from ppPv-Pnma to I4mm at 64 GPa, respectively. Meanwhile, the relation between the band gap and pressure implies that the band gap value of ppPv-Pnma is 1.56 eV at 40 GPa, making it a potential photovoltaic material. Based on pressure-induced stable structures, the CsGeCl3 quantum dots (QDs) have been fabricated to investigate the excited-state properties by tuning ultrafast laser pulses based on time-dependent density functional theory (TDDFT). The excited-state properties show that CsGeCl3 QDs have a wider absorption range compared with their bulk materials and their optical responses can be regulated by changing the laser intensity and wavelength. Our results further reveal that the R3m-QDs exhibit excellent optical performance and have potential applications in optoelectronic devices.

Lactobacillus acidophilus ameliorates obesity in mice through modulation of gut microbiota dysbiosis and intestinal permeability.

Obesity associated with low-grade chronic inflammation and intestinal dysbiosis is considered as a worldwide public health crisis. In the meanwhile, different probiotics have demonstrated beneficial effects on this condition, thus increasing the interest in the development of probiotic treatments. In this context, the aim of this study is to investigate the anti-obesity effects of potential probiotic Lactobacillus acidophilus isolated from the porcine gut. Then, it is found that L. acidophilus reduces body weight, fat mass, inflammation and insulin resistance in mice fed with a high-fat diet (HFD), accompanied by activation in brown adipose tissue (BAT) as well as improvements of energy, glucose and lipid metabolism. Besides, our data indicate that L. acidophilus not only reverses HFD-induced gut dysbiosis, as indicated by the decreased Firmicutes-to-Bacteroidetes ratios and endotoxin bearing Gram-negative bacteria levels, but also maintains intestinal barrier integrity, reduces metabolic endotoxemia, and inhibits the TLR4 / NF- κB signaling pathway. In addition, the results of microbiome phenotype prediction by BugBase and bacterial functional potential prediction using PICRUSt show that L. acidophilus treatment improves the gut microbiota functions involving metabolism, immune response, and pathopoiesia. Furthermore, the anti-obesity effect is transmissible via horizontal faeces transfer from L. acidophilus-treated mice to HFD-fed mice. According to our data, it is seen that L. acidophilus could be a good candidate for probiotic of ameliorating obesity and associated diseases such as hyperlipidemia, nonalcoholic fatty liver diseases, and insulin resistance through its anti-inflammatory properties and alleviation of endothelial dysfunction and gut dysbiosis.

Pressure-induced reconstructive phase transitions, polarization with metallicity, and enhanced hardness in antiperovskite MgCNi3.

In general, hydrostatic pressure can suppress electrical polarization, instead of creating and/or enhancing polarization like strain engineering. Here, a combination of first-principles calculations and CALYPSO crystal structures prediction is used to point out that hydrostatic pressure applied on antiperovskite MgCNi3 can stabilize polarization with metallicity, and thus a polar metal can exist under high pressure. Strikingly, the metallic polar phase of MgCNi3 exhibits an original linear-cubic coupling between polar and nonpolar modes, resulting in an asymmetrical double-well when the polarization is switched. Moreover, another novel phase of MgCNi3 under high pressure possesses an enhanced hardness stemming from a robust s-s electrons interaction of an unexpected C-C bond, rather than typical sp3 orbital hybridization. These discoveries open new routes to design superhard materials and polar metals.

Two-Dimensional Fe8N Nanosheets: Ferromagnets and Nitrogen Diffusion.

We perform a first-principles study and identify two intriguing ferromagnets, hollow-Fe8N (H-Fe8N) and bridge-Fe8N (B-Fe8N) monolayers, by extensive structural searches. Both H-Fe8N and B-Fe8N nanosheets are buckled triangular lattices with a similar motif, but they are distinguishable by the positions of N atoms. The magnetic and electronic properties show that H-Fe8N is a low-spin ferromagnet; in contrast, B-Fe8N is a high-spin ferromagnet, which originates from the 3d orbital splitting of the Fe atom due to the low/high symmetric crystal field. Surprisingly, two stable Fe8N monolayers can be transferred to each other by N atom diffusion from the bridge position to the hollow position with the migration energy barrier of 1.5 eV. The energy barrier is affected by introduced Fe defects and rare earth metal dopants. These findings introduce a new tactic to regulate the 2D Fe-nitride monolayers at the atomic scale.

Insights into the Structures and Bonding of Medium-Sized Cerium-Doped Boron Clusters.

Since the discovery of metal-doped boron clusters attracted great significance to create a new class of materials, research interests have been directed to chemical bonding and structural evolution of lanthanide boride clusters. Here, we perform an extensive ground-state structure search for the CeBn and CeBn- clusters in the size range from 9 to 18 using the Crystal structure AnaLYsis by Particle Swarm Optimization method and density functional theory optimization. It is found that the ground-state structures in both neutral and anionic series possess half-sandwich geometry. The host boron moiety in neutral series has a tendency to form borophene-like geometry. The pentagonal and hexagonal holes are more common in the larger anionic CeBn- series. The theoretical photoelectron spectroscopy has been simulated by applying time-dependent density functional theory calculations. The neutral CeB14 cluster is identified as a magic cluster on the basis of its robust relative stability with respect to its neighbors. Electronic structure and chemical bonding analyses reveal that the CeB14 cluster possesses a large HOMO-LUMO gap and enhanced stability with strong delocalized π and δ bonding via interactions between the Ce 5d- and B 2p-AOs.

Dissociation of dinitrogen on iron clusters: a detailed study of the Fe16 + N2 case.

The coalescence of two Fe8N as well as the structure of the Fe16N2 cluster were studied using density functional theory with the generalized gradient approximation and a basis set of triple-zeta quality. It was found that the coalescence may proceed without an energy barrier and that the geometrical structures of the resulting clusters depend strongly on the mutual orientations of the initial moieties. The dissociation of N2 is energetically favorable on Fe16, and the nitrogen atoms share the same Fe atom in the lowest energy state of the Fe16N2 species. The attachment of two nitrogen atoms leads to a decrease in the total spin magnetic moment of the ground-state Fe16 host by 6 µB due to the peculiarities of chemical bonding in the magnetic clusters. In order to gain insight into the dependence of properties on charge and to estimate the bonding energies of both N atoms, we performed optimizations of Fe16N and the singly charged ions of both Fe16N2 and Fe16N. It was found that the electronic properties of the Fe16N2 cluster, such as electron affinity and ionization energy, do not appreciably depend on the attachment of nitrogen atoms but that the average binding energy per atom changes significantly. The lowering in total energy due to the attachment of two N atoms was found to be nearly independent of charge. The IR and Raman spectra were simulated for Fe16N2 and its ions, and it was found that the positions of the most intense peaks in the IR spectra strongly depend on charge and therefore present fingerprints of the charged states. The chemical bonding in the ground-state Fe16N20,±1 species was described in terms of the localized molecular orbitals.