Formation Rate Research Articles

LbSakA-mediated phosphorylation of the scaffolding protein LbNoxR in the ectomycorrhizal basidiomycete Laccaria bicolor regulates NADPH oxidase activity, ROS accumulation and symbiosis development.

Ectomycorrhizal symbiosis, which involves mutually beneficial interactions between soil fungi and tree roots, is essential for promoting tree growth. To establish this symbiotic relationship, fungal symbionts must initiate and sustain mutualistic interactions with host plants while avoiding host defense responses. This study investigated the role of reactive oxygen species (ROS) generated by fungal NADPH oxidase (Nox) in the development of Laccaria bicolor/Populus tremula × alba symbiosis. Our findings revealed that L. bicolor LbNox expression was significantly higher in ectomycorrhizal roots than in free-living mycelia. RNAi was used to silence LbNox, which resulted in decreased ROS signaling, limited formation of the Hartig net, and a lower mycorrhizal formation rate. Using Y2H library screening, BiFC and Co-IP, we demonstrated an interaction between the mitogen-activated protein kinase LbSakA and LbNoxR. LbSakA-mediated phosphorylation of LbNoxR at T409, T477 and T480 positively modulates LbNox activity, ROS accumulation and upregulation of symbiosis-related genes involved in dampening host defense reactions. These results demonstrate that regulation of fungal ROS metabolism is critical for maintaining the mutualistic interaction between L. bicolor and P. tremula × alba. Our findings also highlight a novel and complex regulatory mechanism governing the development of symbiosis, involving both transcriptional and posttranslational regulation of gene networks.

Large-Scale Experimental Investigation of Hydrate-Based Carbon Dioxide Sequestration

Hydrate-based CO2 sequestration is a novel approach that can not only realize permanent CO2 sequestration but can also form an artificial cap to prevent its upward migration. In this work, a self-developed large-scale 3D apparatus was employed to investigate hydrate formation characteristics in hydrate-based CO2 sequestration at a constant liquid CO2 injection rate through a vertical well for the first time. Temperature and pressure evolutions in the sediment were analyzed in detail. Key indicators, including cumulative sequestered CO2, CO2 in hydrate and liquid phases, the instantaneous hydrate conversion, and liquid CO2 retention rates, were calculated. The results show that hydrate continuously forms with increased CO2 injection and exhibits strong heterogeneity due to the variation in hydrate formation rate and quantity. Severe liquid CO2 heterogeneous figuring phenomena occur since hydrate deteriorates the effective pore structure and topology, resulting in relatively small cumulative sequestered CO2 when a large amount of CO2 is released from the outlet. Meanwhile, the instantaneous hydrate conversion and liquid CO2 retention rates have large fluctuations owing to water consumption and variation in the effective contact area between liquid CO2 and water. However, hydrate formation does not cause blockage of wellbore and formation nearby under given experimental conditions, which is beneficial for hydrate formation in deeper sediment. This study provides insights into hydrate formation and liquid CO2 immigration regularity during hydrate-based CO2 sequestration and demonstrates its feasibility at a field scale.

Construction of indirect dual S-scheme heterojunction CN/AP/AW mediated by Ag nanoparticles enables efficient CO2-to-CH4 photoreduction

The highly selective product generation of photocatalytic CO2 reduction is greatly hampered by the multi-electron transfer process. In this work, Ag nanoparticle mediated indirect dual S-scheme compact heterojunction CN/AP/AW was successfully prepared through varying the ratio of Na2HPO4·12H2O and Na2WO4·2H2O. In pure water, the formation rate and selectivity of CH4 reached 18.49 μmol·g−1·h−1 and 94.3 % under simulated sunlight, with a sharp contrast to CN without CH4. The multi-channel directional transfer of electrons was realized by the construction of heterojunction, which also overcomes the inherent low REDOX capacity issues of conventional type-I and type-II heterojunction. In addition to addressing the weak interfacial contact that often occurs in terpolymer, Ag nanoparticles further accelerate electron transfer as an electron capturer, resulting in rapid unwanted electron-hole recombination. Possible reaction pathways and the cause of high selectivity were predicted by in situ FT-IR. This work provides guidance for the directional and efficient generation of CO2-to-CH4.

Understanding the radio luminosity function of star-forming galaxies and its cosmological evolution

Abstract We explore the redshift evolution of the radio luminosity function (RLF) of star-forming galaxies using galform, a semi-analytic model of galaxy formation and a dynamo model of the magnetic field evolving in a galaxy. Assuming energy equipartition between the magnetic field and cosmic rays, we derive the synchrotron luminosity of each sample galaxy. In a model where the turbulent speed is correlated with the star formation rate, the RLF is in fair agreement with observations in the redshift range 0 ≤ z ≤ 2. At larger redshifts, the structure of galaxies, their interstellar matter and turbulence appear to be rather different from those at z ≲ 2, so that the turbulence and magnetic field models applicable at low redshifts become inadequate. The strong redshift evolution of the RLF at 0 ≤ z ≤ 2 can be attributed to an increased number, at high redshift, of galaxies with large disc volumes and strong magnetic fields. On the other hand, in models where the turbulent speed is a constant or an explicit function of z, the observed redshift evolution of the RLF is poorly captured. The evolution of the interstellar turbulence and outflow parameters appear to be major (but not the only) drivers of the RLF changes. We find that both the small- and large-scale magnetic fields contribute to the RLF but the small-scale field dominates at high redshifts. Polarisation observations will therefore be important to distinguish these two components and understand better the evolution of galaxies and their nonthermal constituents.

Structural evolution in S-vacancy-rich Co@Co9S8 during selective benzyl alcohol electrooxidation reaction

Electrooxidation of organics using electrons as oxidants is a clean approach to produce commodity chemicals. However, designing an electrocatalyst with superior performance at low cell voltage remains a challenge. In this study, a series of VS-Co@Co9S8 electrocatalysts were fabricated by thermal reduction method using MOFs as templates. The catalytic oxidation performance and reaction mechanism of such specimens for benzyl alcohol were comprehensively analyzed by electrochemical measurement method and ex-situ structure characterization. The results show that Co@Co9S8-30 M has a unique three-dimensional (3D) micro cubic structure with abundant S vacancy (VS). These features accelerate the electrons and substrate transfer as well as provide plentiful active sites for benzyl alcohol electrooxidation reaction (BAOR). Consequently, the Co@Co9S8-30 M presented outstanding catalytic activity. The overpotential of 10 mA cm−2 (η10) was only 265.4 mV for BAOR. The conversion rate and benzoic acid selectivity were achieved to 72% and 90%, respectively. Particularly, the formation rate of benzoic acid was 7.247 mmol·gcat.−1·h−1. Moreover, the Co@Co9S8-30 M exhibited superior durability over 135 h. The coordination number of octahedral metal sites in Co9S8 did not match the number of Co 3 d orbital electrons, resulting in the weakening of bonding strength between Co and S elements. Thus, the Co@Co9S8 was reconstructed to Co3O4@CoOOH. Based on this assessment, the Co3O4@CoOOH was the active site of BAOR. This work provides theoretical guidance for the design of Co-based catalysts.

Integrating the 2D/2D heterostructure of the MXene monolayer and BiOBr nano-sheets for superior photo-catalysis

The highly efficient photo-oxidation of alcohols has sparked significant potential to cope with environmental pollution and the ever-increasing energy crisis. This study reports a unique Ti3C2/BiOBr (TB) heterojunction with a rich inter-face based on in situ exfoliation of MXene and subsequently anchored onto BiOBr sheets. The TB nano-composites exhibited substantially improved photo-catalytic activity towards the photo-oxidation of benzyl alcohol (BA) to benzaldehyde and achieved a formation rate of 1.73 mmol g−1 h−1, greater than pristine BiOBr. The ultra-thin inter-facial contact boosted the oxygen vacancies (Ov) and Ti3+ and possessed the most negative adsorption energy, which boosted the transfer and separation of inter-facial charge carriers and the adsorption and dissociation of BA. Overall, the successful synthesis of TB composite, along with its exceptional photo-catalytic performance, offers valuable insights for applications in green chemistry and environmental remediation.

The HMG-box module in FACT is critical for suppressing epigenetic variegation of heterochromatin in fission yeast.

Chromatin condensation state is the key for retrieving genetic information. High-mobility group protein (HMG) proteins exhibit DNA-binding and bending activities, playing an important role in the regulation of chromatin structure. We have shown that nucleosomes tightly packaged into heterochromatin undergo considerable dynamic histone H2A-H2B maintenance via the direct interaction between HP1/Swi6 and facilitate chromatin transcription (FACT), which is composed of the Spt16/Pob3 heterodimer and Nhp6. In this study, we analyzed the role of Nhp6, an HMG box protein, in the FACT at heterochromatin. Pob3 mutant strains showed derepressed heterochromatin-dependent gene silencing, whereas Nhp6 mutant strains did not show significant defects in chromatin regulation or gene expression, suggesting that these two modules play different roles in chromatin regulation. We expressed a protein fusing Nhp6 to the C-terminus of Pob3, which mimics the multicellular FACT component Ssrp1. The chromatin-binding activity of FACT increased with the number of Nhp6 fused to Pob3, and the heterochromatin formation rate was promoted more strongly. Furthermore, we demonstrated that this promotion of heterochromatinization inhibited the heterochromatic variegation caused by epe1+ disruption. Heterochromatic variegation can be observed in a variety of regulatory steps; however, when it is caused by fluctuations in chromatin arrangement, it can be eliminated through the strong recruitment of the FACT complex.

IpaA reveals distinct modes of vinculin activation during Shigella invasion and cell-matrix adhesion.

Vinculin is a cytoskeletal linker strengthening cell adhesion. The Shigella IpaA invasion effector binds to vinculin to promote vinculin supra-activation associated with head-domain-mediated oligomerization. Our study investigates the impact of mutations of vinculin D1D2 subdomains' residues predicted to interact with IpaA VBS3. These mutations affected the rate of D1D2 trimer formation with distinct effects on monomer disappearance, consistent with structural modeling of a closed and open D1D2 conformer induced by IpaA. Notably, mutations targeting the closed D1D2 conformer significantly reduced Shigella invasion of host cells as opposed to mutations targeting the open D1D2 conformer and later stages of vinculin head-domain oligomerization. In contrast, all mutations affected the formation of focal adhesions (FAs), supporting the involvement of vinculin supra-activation in this process. Our findings suggest that IpaA-induced vinculin supra-activation primarily reinforces matrix adhesion in infected cells, rather than promoting bacterial invasion. Consistently, shear stress studies pointed to a key role for IpaA-induced vinculin supra-activation in accelerating and strengthening cell-matrix adhesion.

PLGA and PDMS-based in situ forming implants loaded with rosuvastatin and copper-selenium nanoparticles: a promising dual-effect formulation with augmented antimicrobial and cytotoxic activity in breast cancer cells.

Breast cancer is among the most prevalent tumors worldwide. In this study, in-situ forming implants (ISFIs) containing rosuvastatin calcium were prepared using three types of poly (D, L-lactic-co-glycolic acid) (PLGA), namely, PLGA 50/50 with ester terminal and PLGA 75/25 with ester or acid terminal. Additionally, polydimethylsiloxane (PDMS) was added in concentrations of 0, 10, 20, and 30% w/v to accelerate matrix formation. The prepared ISFIs were characterized for their rheological behaviors, rate of matrix formation, and in-vitro drug release. All the prepared formulations revealed a Newtonian flow with a matrix formation rate between 0.017 and 0.059mm/min. Generally, increasing the concentration of PDMS increased the matrix formation rate. The prepared implants' release efficiency values ranged between 46.39 and 89.75%. The ISFI containing PLGA 50/50 with 30% PDMS was selected for further testing, as it has the highest matrix formation rate and a promising release efficiency value. Copper-selenium nanoparticles were prepared with two different particle sizes (560 and 383nm for CS1 and CS2, respectively) and loaded into the selected formulation to enhance its anticancer activity. The unloaded and loaded implants with rosuvastatin and copper-selenium nanoparticles were evaluated for their antibacterial activity, against Gram-positive and negative microorganisms, and anticancer efficacy, against MCF-7 and MDA-MB-231 cell lines. The results confirmed the potency of rosuvastatin calcium against cancer cells and the synergistic effect when loaded with smaller particle sizes of copper-selenium nanoparticles. This formulation holds a considerable potential for efficient breast cancer therapy.

PPARG is dispensable for bovine embryo development up to tubular stages.

Following blastocyst hatching, ungulate embryos undergo a prolonged preimplantation period termed conceptus elongation. Conceptus elongation constitutes a highly susceptible period for embryonic loss and the embryonic requirements during this process are largely unknown, but multiple lipid compounds have been identified in the fluid nourishing the elongating conceptuses. Peroxisome proliferator-activated receptors (PPARs) mediate the signaling actions of prostaglandins and other lipids and, between them, PPARG has been pointed out to play a relevant role on conceptus elongation by a functional study that depleted PPARG in both uterus and conceptus. The objective of this study has been to determine if embryonic PPARG is required for bovine embryo development. To that aim, we have generated bovine PPARG KO embryos in vitro by two independent gene ablation strategies and assess their developmental ability. In vitro development to Day (D) 8 blastocyst was unaffected by PPARG ablation, as total, inner cell mass and trophectoderm cell numbers were similar between WT and KO D8 embryos. In vitro post-hatching development to D12 was also comparable between different genotypes, as embryo diameter, epiblast cell number, and embryonic disc formation and hypoblast migration rates were unaffected by the ablation. The development to tubular stages equivalent to E14 was assessed in vivo, following a heterologous embryo transfer experiment, observing that the development of extra-embryonic membranes and of the embryonic disc was not altered by PPARG ablation. In conclusion, PPARG ablation did not impaired bovine embryo development up to tubular stages.

Effects of centrifugation treatment before electroporation on gene editing in pig embryos.

Genetic mosaicism, characterized by multiple genotypes within an individual, is considered an obstacle to CRISPR/Cas9 genome editing in animal models. Despite the various strategies for minimizing mosaic mutations, no definitive methods exist to eliminate them. This study aimed to enhance gene editing efficiency in porcine zygotes using CRISPR/Cas9, which targets specific genes through centrifugation and zona pellucida removal before electroporation. Centrifugation at 2000 × g did not adversely affect blastocyst formation rates in zygotes electroporated with gRNA targeting the GGTA1 gene; instead, it led to increased total and monoallelic mutation rates compared with control zygotes without centrifugation. However, the groups had no significant differences in biallelic mutation rates. In zygotes electroporated with gRNA targeting the CMAH gene, centrifugation treatments exceeding 1000 × g significantly increased both biallelic mutation rates and mutation efficiency. The combination of centrifugation and zona pellucida removal did not have a detrimental effect on blastocyst formation rates. It led to a higher rate of double biallelic mutations in embryos targeting both GGTA1 and CMAH compared to embryos without centrifugation treatment. In summary, our results demonstrate that pre-electroporation treatments, including centrifugation and zona pellucida removal, positively influenced the reduction of mosaic mutations, with the effectiveness of centrifugation depending on the specific gRNA used.

The opposing effect of acute and chronic Toxoplasma gondii infection on tumor development

BackgroundThe interplay between Toxoplasma gondii infection and tumor development is intriguing and not yet fully understood. Some studies showed that T. gondii reversed tumor immune suppression, while some reported the opposite, stating that T. gondii infection promoted tumor growth.MethodsWe created three mouse models to investigate the interplay between T. gondii and tumor. Model I aimed to study the effect of tumor growth on T. gondii infection by measuring cyst number and size. Models II and III were used to investigate the effect of different stages of T. gondii infection on tumor development via flow cytometry and bioluminescent imaging. Mouse strains (Kunming, BALB/c, and C57BL/6J) with varying susceptibilities to tumors were used in the study.ResultsThe size and number of brain cysts in the tumor-infected group were significantly higher, indicating that tumor presence promotes T. gondii growth in the brain. Acute T. gondii infection, before or after tumor cell introduction, decreased tumor growth manifested by reduced bioluminescent signal and tumor size and weight. In the tumor microenvironment, CD4+ and CD8+ T cell number, including their subpopulations (cytotoxic CD8+ T cells and Th1 cells) had a time-dependent increase in the group with acute T. gondii infection compared with the group without infection. However, in the peripheral blood, the increase of T cells, including cytotoxic CD8+ T cells and Th1 cells, persisted 25 days after Lewis lung carcinoma (LLC) cell injection in the group with acute T. gondii. Chronic T. gondii infection enhanced tumor growth as reflected by increase in tumor size and weight. The LLC group with chronic T. gondii infection exhibited decreased percentages of cytotoxic CD8+ T cells and Th1 cells 25 days post-LLC injection as compared with the LLC group without T. gondii infection. At week 4 post-LLC injection, chronic T. gondii infection increased tumor formation rate [odds ratio (OR) 1.71] in both KM and BALB/c mice.ConclusionsOur research elucidates the dynamics between T. gondii infection and tumorigenesis. Tumor-induced immune suppression promoted T. gondii replication in the brain. Acute and chronic T. gondii infection had opposing effects on tumor development.Graphical

Pt3Mn/SiO2 + ZSM-5 Bifunctional Catalyst for Ethane Dehydroaromatization

Ethane dehydroaromatization (EDA) is a potentially attractive process for converting ethane to valuable aromatics such as benzene, toluene, and xylene (BTX). In this study, a Pt3Mn/SiO2 + ZSM-5 bifunctional catalyst was used to investigate the effect of dehydrogenation and the Brønsted acid catalyst ratio, hydrogen partial pressure, and reaction temperature on the product distributions for EDA. Pt3Mn/SiO2 + ZSM-5 with a 1/1 weight ratio showed the highest ethane conversion rate and BTX formation rate. Ethylene is initially formed by dehydrogenation by the Pt3Mn catalyst, which undergoes secondary reactions on ZSM-5, forming C3+ reaction intermediates. The latter form final products of CH4 and BTX. At conversions from 15 to 30%, the BTX selectivities are 82–90%. For all bifunctional catalysts, the ethane conversion significantly exceeds the ethane–ethylene equilibrium conversion due to reaction to secondary products. Low H2 partial pressures did not significantly alter the product selectivity or conversion. However, higher H2 partial pressures resulted in increased methane and decreased BTX selectivity. The excess hydrogen saturated the olefin intermediates to form alkanes, which produced methane by monomolecular cracking on ZSM-5. With an increasing reaction temperature from 550 °C to 650 °C, the benzene selectivity increased, while the highest BTX selectivity was obtained at 600 to 650 °C.

Evaluation and Modeling of the Rate of Formation of Lath Martensite in Fe-C Alloys, Extracted from Ultra-Rapid Quenching Experiments

AbstractIsothermal information is rarely available for the formation of martensite in Fe or Fe alloys due to a very high rate of transformation compared to the rate of heat conduction. Such information has now been extracted for lath martensite in some sets of Fe alloys from available information on ultra-rapid quenching but only at a single temperature for each alloy, related to its two MS temperatures. The temperature dependence could, thus, be studied only on binary sets of alloys. Those results have been applied to mathematical models based on the Arrhenius equation and illustrated with Arrhenius plots. For three sets of binary Fe alloys, a large group of rates came close to the rate of an almost pure and carbon-free Fe-C alloy. It illustrated that Cr, Ni, and Ru in low contents have relatively small effects on the rate of formation of lath martensite in Fe. It also demonstrated that the present measurements have considerable reproducibility. In contrast, a set of Fe-C alloys did not give a straight line in the Arrhenius plot. Using a new mathematical model based on the concept of the Arrhenius equation to express the effect of carbon, it was possible to predict the rate of formation of lath martensite for Fe-C alloys with fixed C content and their temperature dependencies which are not available experimentally due to the very high rate of formation.

The SAMI Galaxy Survey: Impact of star formation and AGN feedback processes on the ionized gas velocity dispersion

Abstract We investigate the influence of star formation and instantaneous AGN feedback processes on the ionized gas velocity dispersion in a sample of 1285 emission-line galaxies with stellar masses log (M*/M⊙) ≥ 9 from the integral-field spectroscopy SAMI Galaxy Survey. We fit both narrow and broad emission line components using aperture spectra integrated within one effective radius, while ensuring the elimination of velocity differences between the spectra of individual spaxels. Our analysis reveals that 386 (30 per cent) galaxies can be adequately described using a single emission component while 356 (28 per cent) galaxies require two (broad and narrow) components. Galaxies characterized by high mass, elevated star formation rate surface density, or type-2 AGN-like emissions tend to feature an additional broad emission-line component, leading to their classification as double-component galaxies. We explore the correlations between M* and gas velocity dispersions, highlighting that the prominence of the broad component significantly contributes to elevating the gas velocity dispersion. Galaxies displaying AGN-like emission based on optical definitions show enhanced gas velocity dispersions. In star-forming galaxies, both stellar mass and star-formation rate surface density substantially contribute to the velocity dispersion of the narrow component. Increased star-forming activity appears to elevate the velocity dispersion of the narrow component. The broad component exhibits a weaker dependence on stellar mass and is primarily driven by galactic outflows. We suggest that strong star forming activity leads to the formation of a broad emission-line component, but the impact on inflating gas velocity dispersion is moderate. On the other hand, AGN-driven outflows appear to be a more important contributor to the elevated velocity dispersion of the ionized gas.

High-performance static formation of methane hydrate in fixed bed constructed by incorporating expanded graphite into polyimide foam

Hydrate has been endowed with great potential in energy storage and transportation. However, the kinetics of its formation process has been a challenge, often requiring dynamic mechanical processes that are energy-intensive and cumbersome to operate. Herein, a well-designed expanded graphite (EG)/polyimide (PI) foam was first explored as fixed bed for the formation of methane hydrate. The results demonstrate that the EG/PI fixed bed exhibits a remarkable performance in hydrate formation under static conditions, with a high gas storage capacity of 149 V/V, a short induction time and a rapid formation rate of 13.1 V·V−1·min−1 at 6 MPa and −2 °C, and excellent recyclability, which are attributed to its stable micro/macro structures. Thereinto, the pores of EG serves as gas adsorption and reaction sites, initialing the formation with extremely short induction time. The three-dimensional framework of PI foam supports the uniform dispersion of EG particles and enables the efficient formation of hydrate under static condition. The EG/PI fixed bed decreases the water freezing point and leads to a high supercooling that facilitates the rapid nucleation of hydrate. Meanwhile, the fixed bed provides extensive mass-transfer channels, sufficient growing space, and superior heat conductivity, which contribute to the hydrate growth under static condition. This work not only offers a novel strategy for fabricating high-performance fixed bed, but also provides an insight into its promotion mechanism in hydrate formation.

Feasibility study utilizing a combinatorial functional precision medicine platform, Optim.AI, to help guide treatment for pancreatic cancer.

e13614 Background: Functional screening methods are increasingly applied to guide patient treatment and could be beneficial in indications with poor survival and response rates, such as pancreatic cancer. However, challenges faced when implementing ex vivo testing include complexities in obtaining sufficient tumor cells for different cancer types and maximizing the number of treatments tested with limited sample material. The latter is especially significant in informing clinical decision making as combination therapies are common with cancer, exponentially increasing the number of regimens to select from. To address this hurdle, we developed Optim.AI, a combinatorial functional precision medicine platform, which utilizes efficiently designed experiments and small data AI to expand to over 530,000 phenotypic response data points and predictively rank all actionable treatments within a 12-drug panel. In this feasibility study, we explored the application of Optim.AI on patient-derived tumor cells in pancreatic cancer. Methods: We established a procedure to run Optim.AI with isolated tumor cells from pancreatic cancer patients. After dissociation, these cells were then incubated to allow for 3D organoid formation within the following week. Upon organoid formation, the cells were treated with an FDA-approved panel of chemotherapy and targeted drugs. Cell viability was quantified post-drug treatment for analysis with Optim.AI software to rank all possible single to 4-drug combinatorial therapies for report generation. Results: The viability of the cells post-processing was high (mean = 97.4% live cells), passing the quality check of having at least 60% live cells before proceeding with Optim.AI testing. The success rate of organoid formation was 100% within 1 week of sample processing. The turnaround time from the receipt of samples to dissemination of the reports to clinicians was approximately a week (mean = 7.67 days). Z’ factor, a measurement of statistical effect size for high throughput screening, was demonstrated to be more than 0.5 for the reports generated, indicative of very good assays. The top ranked drug combinations were sensitive, with their normalized cell viability reported to be under 0.2, while the prior line of treatment was shown to be resistant, 100% concordant with previously observed clinical outcomes. Notably, Gemcitabine with either a HDAC or PI3K inhibitor was ranked high amongst the reports generated. Conclusions: Optim.AI had a high success rate in generating reports within a very short timeframe for pancreatic cancer. Comparing the top ranked therapies against the prior lines of treatment allows the clinicians to better evaluate the alternative treatments. Based on this initial feasibility study, Optim.AI could potentially be viable in guiding clinicians in managing treatment options for pancreatic cancer patients.

Effect of method of preparation of Ni and/or Cu supported on ZSM-5 catalysts for the aqueous phase hydrogenation of levulinic acid to γ-valerolactone

A series of Cu and Ni supported on ZSM-5 catalysts were synthesized by ion exchange (IE) and impregnation (IMP) techniques and examined for the aqueous phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) at atmospheric pressure. Hydrogenation of LA to GVL proceeds through LA dehydration to AL (angelica lactone) and subsequent hydrogenation of it to GVL, emphasizing the combined role of an acid and a metal site present on the catalyst surface. The interaction of Cu and/or Ni with ZSM-5 was elucidated using various characterization techniques such as powder XRD, XPS, H2-TPR, NH3-TPD, CO and/or H2 pulse chemisorption and SS NMR techniques. The CO chemisorption results indicated a lower uptake on Cu-ZSM-5(IMP) than on Cu-ZSM-5(IE). The H2 uptake was lower on Ni-ZSM-5(IE) than on Ni-ZSM-5(IMP). In the comparative analysis, the Ni-ZSM-5(IMP) catalyst exhibited a high rate of GVL formation, while the Cu-ZSM-5(IE) catalyst displayed a larger proportion of AL formation than the other catalysts prepared under similar protocols. The influence of the surface active sites on the product distribution was rationalized based on the physico-chemical characteristics of the fresh and reduced catalysts.

JWST and ALMA Discern the Assembly of Structural and Obscured Components in a High-redshift Starburst Galaxy

We present observations and analysis of the starburst PACS-819 at z = 1.45 (M * = 1010.7 M ⊙), using high-resolution (0.″1; 0.8 kpc) Atacama Large Millimeter/submillimeter Array (ALMA) and multiwavelength JWST images from the COSMOS-Web program. Dissimilar to Hubble Space Telescope (HST) ACS images in the rest-frame UV, the redder NIRCam and MIRI images reveal a smooth central mass concentration and spiral-like features, atypical for such an intense starburst. Through dynamical modeling of the CO (J = 5–4) emission with ALMA, PACS-819 is rotation dominated and thus consistent with having a disk-like nature. However, kinematic anomalies in CO and asymmetric features in the bluer JWST bands (e.g., F150W) support a more disturbed nature likely due to interactions. The JWST imaging further enables us to map the distribution of stellar mass and dust attenuation, thus clarifying the relationships between different structural components not discernible in the previous HST images. The CO (J = 5–4) and far-infrared dust continuum emission are cospatial with a heavily obscured starbursting core (<1 kpc) that is partially surrounded by much less obscured star-forming structures including a prominent arc, possibly a tidally distorted dwarf galaxy, and a massive clump (detected in CO), likely a recently accreted low-mass satellite. With spatially resolved maps, we find a high molecular gas fraction in the central area reaching ∼3 (M gas/M *) and short depletion times (M gas/SFR ∼ 120 Myr, where SFR is star formation rate) across the entire system. These observations provide insights into the complex nature of starbursts in the distant Universe and underscore the wealth of complementary information from high-resolution observations with both ALMA and JWST.

Star Formation Rates in [Ne V] 3426 Å Selected Active Galactic Nuclei: Evidence for a Decrease along the Main Sequence?

Studying the behavior along the galaxy main sequence is key in furthering our understanding of the possible connection between active galactic nucleus (AGN) activity and star formation. We select a sample of 1215 AGN from the catalog of Sloan Digital Sky Survey galaxy properties from the Portsmouth group by detection of the high-ionization [Ne v] 3426 Å emission line. Our sample extends from 1040 to 1042.5 erg s−1 in [Ne v] luminosity in a redshift range z = 0.17 to 0.57. We compare the specific star formation rates (sSFRs; SFR scaled by galaxy mass) obtained from the corrected [O ii] and Hα luminosities, and the spectral energy distribution (SED)–determined values from Portsmouth. We find that the emission-line-based sSFR values are unreliable for the [Ne v] sample due to the AGN contribution, and proceed with the SED sSFRs for our study of the main sequence. We find evidence for a decrease in sSFR along the main sequence in the [Ne v] sample, which is consistent with results from the hard X-ray Burst Alert Telescope AGN sample, which extends to lower redshifts than our [Ne v] sample. Although we do not find evidence that the concurrent AGN activity is suppressing star formation, our results are consistent with a lower gas fraction in the host galaxies of the AGN as compared to that of the star-forming galaxies. If the evacuation of gas, and therefore suppression of star formation, is due to AGN activity, it must have occurred in a previous epoch.