Pool Species Research Articles

Grazing regimes alter the fate of 15N‐labeled urea in a temperate steppe

AbstractClarifying the fate of different nitrogen (N) species in different pools of terrestrial ecosystems is a prerequisite for a comprehensive understanding of the influence of human activities on the N cycle. Grazing has always been an important way of grassland management for centuries in the temperate grasslands of North China. However, how grazing regimes affect the N fate of urea derived from the livestock in the plant–soil systems of grazed grasslands remains poorly understood. Therefore, an in situ three‐factor (grazing regime, soil depth, and sampling time) 15N‐labeling experiment in a temperate steppe was conducted to answer this question. After 48 days of 15N labeling, the 15N recovered in shoots under no grazing (7.3% ± 1.8%) was approximately 2.3 times of that under rotational (3.2% ± 0.4%) and 2.5 times of that under continuous overgrazing (2.9% ± 0.5%). More 15N was recovered in roots under rotational than continuous overgrazing (19.8% ± 2.4% vs. 10.4% ± 0.5%, respectively), indicating that rotational overgrazing could promote more N retention in the roots. However, the 15N recovered in the soil was lower under continuous (23.7% ± 2.0%) than that of no grazing (42.0% ± 5.6%). Additionally, overgrazing reduced the magnitude of the soil active N pool in microbial biomass N and soluble N relative to no grazing. The grazing regimes would have significantly influenced both the soil and plants. That is to say, grazing regimes have directly impacted plant growth, and subsequently indirectly affected soil properties. Overgrazing often led to excessive vegetation consumption, resulting in decreased soil water content (SWC) and reduced soil organic carbon (SOC), ultimately caused alterations in plant species composition. The retention of 15N within the plant–soil system under continuous overgrazing was notably lower compared to that of no grazing. Continuous overgrazing has led to a shift in the dominant plant species from Leymus chinensis to Stipa grandis, by decreasing the proportion of perennial grasses by 10%, and increasing the annual and biennial plants by 8%. The fate of 15N was also altered in response to the variations in grazing regimes. Consequently, the recovery of 15N within the plant–soil system under continuous overgrazing was significantly lower compared to that of no grazing. In conclusion, overgrazing reduces the recovery of 15N within the plant–soil system in the temperate steppe, and rotational grazing is more preferable over continuous grazing as it could promote higher N retention in grassland ecosystems.

Evaluation of pathogenicity and antifungal resistance of frequently occurred Aspergillus and Fusarium species in swimming pools in selected hotels in Ekiti state

Background: Swimming pools have been reported as critical fungal reservoirs. This study was designed to investigate fungal populations in swimming pools as well as detect the presence of virulence factors in the recovered isolates. Methods: Estimation of the mycobiota in the swimming pools sampled was done and isolates recovered were identified using colonial, morphology and molecular methods. Also, virulence factors: lipase, keratinase, laccase, hydrophobicity and biofilm formation were also determined using standard methods while antifungal susceptibility was done using clinically approved methods. Also, the presence of metalloprotease and protease gene was detected using PCR. Results: Out of the 75 samples, 47 showed fungal growth, with an isolation rate of 25.5%, 34.0%, and 40.4% from the surface, bottom, and edges of the pools respectively. Six fungi species were isolated viz: Candida tropicalis, Aspergillus flavus, Aspergillus niger, Fusarium oxysporum, and Fusarium verticilloides. C. tropicalis had the highest isolation rate at 41.7%. The fungi possessed virulence factors, with keratinase and lipase being the most common. All isolates were resistant to itraconazole, while none were resistant to fluconazole. The metalloprotease gene was detected in A. flavus, F. verticilliodes, and F. oxysporum. Conclusion: Our study revealed that the fungi recovered from the swimming pool possessed virulence factors that can enhance their infectivity.

Rocaglamide regulates iron homeostasis by suppressing hepcidin expression

The anemia of inflammation (AI) is characterized by the presence of inflammation and abnormal elevation of hepcidin. Accumulating evidence has proved that Rocaglamide (RocA) was involved in inflammation regulation. Nevertheless, the role of RocA in AI, especially in iron metabolism, has not been investigated, and its underlying mechanism remains elusive. Here, we demonstrated that RocA dramatically suppressed the elevation of hepcidin and ferritin in LPS-treated mice cell line RAW264.7 and peritoneal macrophages. In vivo study showed that RocA can restrain the depletion of serum iron (SI) and transferrin (Tf) saturation caused by LPS. Further investigation showed that RocA suppressed the upregulation of hepcidin mRNA and downregulation of Fpn1 protein expression in the spleen and liver of LPS-treated mice. Mechanistically, this effect was attributed to RocA's ability to inhibit the IL-6/STAT3 pathway, resulting in the suppression of hepcidin mRNA and subsequent increase in Fpn1 and TfR1 expression in LPS-treated macrophages. Moreover, RocA inhibited the elevation of the cellular labile iron pool (LIP) and reactive oxygen species (ROS) induced by LPS in RAW264.7 cells. These findings reveal a pivotal mechanism underlying the roles of RocA in modulating iron homeostasis and also provide a candidate natural product on alleviating AI.

Combined Strategies Enable Highly Selective Light Olefins and para-Xylene Production on Single Catalyst Bed.

Achieving multiple high-value-added chemical production through novel reaction processes and shape-selective catalytic strategy is the key to realizing efficient low-carbon catalytic processes. In this work, a methanol-toluene coreaction system was developed, and combined control strategies of reaction pathway guidance and shape-selective catalysis were applied for the successful production of light olefins and para-xylene on single HZSM-5 catalyst bed. Cofeeding toluene additionally provides reactive and flowing aromatic hydrocarbon pool species that change the dominant reaction pathway in the complex network of the methanol reaction on HZSM-5 and promote the formation of ethylene. For the first time, the key reaction intermediates methylmethylenecyclodiene are directly captured and identified by experimental and theoretical techniques. This helps to propose the catalytic cycle for the dominant generation of ethylene and, more importantly, enriches the methanol-to-hydrocarbons (MTH) chemistry and hydrocarbon pool mechanism. Furthermore, 0.4HZSM-5@S-1-CLD, an optimized HZSM-5 catalyst modified by the silicalite-1 epitaxial growth followed by silanization approach, realizes highly selective production of light olefins (especially ethylene) and para-xylene, while excellent reactant activity is maintained. This highly efficient coreaction route gives an important leading significance in synthesizing the raw materials for the polyolefin and polyester industries. The establishment of the combined control strategies provides a model for the joint production of multiple target chemicals in complex catalytic processes.

Exploring the use of metabarcoding to reveal eukaryotic associations with mononchids nematodes.

Nematodes play a vital ecological role in soil and marine ecosystems, but there is limited information about their dietary diversity and feeding habits. Due to methodological challenges, the available information is based on inference rather than confirmed observations. The lack of correct dietary requirements also hampers rearing experiments. To achieve insight into the prey of mononchid nematodes, this study employed high-throughput Illumina paired-end sequencing using universal eukaryotic species 18S primers on 10 pooled mononchid nematode species, namely Mylonchulus brachyuris, M. brevicaudatus, Mylonchulus sp., Clarkus parvus, Prionchulus sp. M. hawaiiensis, M. sigmaturellus, M. vulvapapillatus, Anatonchus sp. and Miconchus sp. The results indicate that mononchids are associated with a remarkable diversity of eukaryotes, including fungi, algae, and protists. While the metabarcoding approach, first introduced here for mononchids, proved to be a simple and rapid method, it has several limitations and crucial methodological challenges that should be addressed in future studies. Ultimately, such methods should be able to evaluate the dietary complexity of nematodes and provide a valuable avenue for unraveling the dietary requirements of previously unculturable nematodes. This can contribute to the methodology of understanding their feeding habits and contributions to ecosystem dynamics.

Wide hybridization in sorghum with tertiary gene pool for diversification of parental lines

AbstractSorghum (S. bicolor) is a great millet that constitutes the staple food in many parts of the world and is cultivated in the semi‐arid tropics. The grain is bestowed with traits that make it amenable for many value‐added products, thus increasing the demand. Considerable progress is achieved in increasing the yield in the past through exploitation of primary gene pool species and secondary gene pool species to a very limited extent, but further increase is challenging and it necessitates bringing in the genetic diversity from other gene pools. Tertiary gene pool of sorghum has not been exploited so far due to limitations of cross‐incompatibility. We accomplished inter‐specific hybridization in sorghum with the wild species of tertiary gene pool. Derivatives from three inter‐specific crosses (ISCs), Sorghum bicolor × S. versicolor (ISC304 and ISC320) and S. bicolor × S. usumbarense (ISC812), with the parental lines of popular Indian sorghum hybrids, 27B and 126B, are developed. Thirteen promising lines are identified, and they are subjected to field evaluation and molecular analysis to develop inter‐specific derivatives that are equivalent to parent progenitors in agronomic traits yet diverse enough genetically. Analysis of phenotypic data in conjunction with genotype data revealed that derivatives of S. usumbarense are promising as compared to derivatives from S. versicolor, derivatives of S. usumbarense are closely clustered as compared to that of S. versicolor, and all the derivatives carry genomic regions from both the parents, with S. bicolor genome being predominant. GGE biplot analysis identified three genotypes (ISC320‐5, ISC320‐2, and ISC812‐2) as highly promising. We successfully generated promising inter‐specific derivatives from the tertiary gene pool in sorghum for ready use in crop improvement programs.

Site- and habitat-dependent variations in the diversity of polychaetes associated with golden kelp Ecklonia radiata holdfasts along the southeast coast of South Africa

Polychaetes are important components of the macrofaunal communities associated with golden kelp Ecklonia radiata holdfasts across different spatial scales. However, the polychaete component varies in different habitat types in response to varying environmental conditions. Here, we compared patterns of variation in Ecklonia radiata holdfast-associated polychaetes between rock pools and gullies along South Africa’s southeast coast. Eighteen species were found in gullies and 28 species in rock pools, with 13 and 16 families represented, respectively. The study sites at Cwebe, Dwesa and Nqabarha had 12, 11 and 20 species, respectively. The rock pools were more species-rich than the gullies, while Nqabarha was the most species-rich site. The composition of species varied both among habitat types and between sites, with a separation in polychaete composition observed between Cwebe and Dwesa. The species that contributed >60% to the distinction between habitat types and among sites were Lepidonotus semitectus, Cirriformia capensis, Eunice aphroditotis, Syllis sp., Chaetopterus variopedatus, L. durbanensis, Arabella iricolor, Lysidice natalensis and Gunnarea gaimardi. The polychaete distribution on kelp holdfasts was influenced by the sediment and geomorphological characteristics of the sampling sites. Our findings highlight the importance of sediment in creating habitat heterogeneity and how this facilitates high species richness in rock pools. However, physical factors explained a small proportion of the variance in the polychaete assemblages. Therefore, biological factors could be more important drivers than abiotic elements, particularly between habitat types.

Evolution of carbon deposits during ethylene aromatization over Zn/ZSM-5

Zn/ZSM-5 catalysts exhibit remarkable catalytic activity in the ethylene aromatization process. Nonetheless, they frequently suffer from rapid deactivation owing to coke deposition. This study investigated the coking process of Zn/ZSM-5 catalyst during the ethylene aromatization, as well as the evolution of carbon deposits and their impact on the catalyst's structure and surface properties. The results showed that, despite ethylene conversion remaining at 100 % during the initial high-activity stable phase (0–24 h), even small amounts of carbon deposition resulted in significant decrease in microporosity and strong acid sites of the catalyst. Methyl-substituted benzene was identified as the primary deposit on the catalyst in the initial reaction stage, as confirmed by infrared (IR) spectroscopy, ultraviolet-Raman (UV-Raman), thermogravimetry-mass spectrometer (TG-MS), gas chromatography-mass spectrometry (GC–MS), and electron paramagnetic resonance (EPR), which can act as an active hydrocarbon pool species for ethylene oligomerization. Thus, the catalyst was able to maintain high ethylene conversion activity despite the loss of some acid sites. However, during the decline in activity period (24–72 h), the composition and location of carbon deposits underwent significant changes. A large number of polycyclic aromatic hydrocarbons formed on the catalyst surface, which resulted in the weakening of the interaction between Zn species and the zeolite, ultimately leading to the transformation into large grain ZnO and decrease in aromatics selectivity. Additionally, the bulky carbon deposits covered the pores of the zeolite, leading consequently to a decrease in ethylene conversion and ultimately catalyst deactivation.

Exploring the relationship between environmental DNA concentration and biomass in Asian giant softshell turtle (Pelochelys cantorii).

In recent years, environmental DNA (eDNA) technology has become an accepted approach for investigating rare and endangered species because of its economic efficiency, high sensitivity, and non-invasiveness. The Asian giant softshell turtle (Pelochelys cantorii) is a first-class protected aquatic animal in China, and traditional resource survey methods have not identified its natural populations for many years. In this study, primers and a TaqMan probe targeting ND5 were designed, reaction conditions were optimized, a standard curve was constructed using synthetic DNA, and an eDNA quantitative PCR (qPCR) detection method was established. The eDNA detection technology for P. cantorii revealed that the number of species in the experimental pools showed a significant linear relationship with the eDNA concentration (p < 0.05). The eDNA concentration was negatively correlated with the length of time after the removal of P. cantorii and retention in the water body for 9 days. The qPCR detection method for P. cantorii eDNA established in this study can be applied to the qualitative detection of P. cantorii in water bodies, as well as to preliminary evaluation of its relative biomass. This can serve as a baseline for the investigation of natural P. cantorii population and the evaluation of its wild release effects.

Microkinetic Simulations of Methanol-to-Olefin Conversion in H-SAPO-34: Dynamic Distribution and Evolution of the Hydrocarbon Pool and Implications for Catalytic Performance

The dominating hydrocarbon pool species (HCPs) in zeolites for methanol-to-olefin (MTO) conversion have been the subject of intense debate for decades due to the diversity of structures and the complexity of reaction networks. We performed microkinetic simulations in a three-site model to study the MTO conversion in industrially relevant H-SAPO-34 zeolite under a wide range of operating conditions. The energetics of 229 and 342 elementary reaction steps were employed, respectively, in the aromatic-based and olefin-based cycles. The dynamic distribution and evolution of the retained aromatic or olefinic HCPs and the origin of olefin products were revealed with respect to reaction conditions. We corroborate that the olefin-based cycle dominates the MTO conversion in H-SAPO-34 under most reaction conditions, and the contribution of the aromatic-based cycle increase with increasing temperature, decreasing pressure, and/or decreasing water partial pressure. The paring route, dedicated highly to propene formation, prevails in the aromatic-based cycle; the side chain route, favoring exclusively ethene formation, only prevails at extremely lower temperatures, higher pressures, and higher water contents. The inherent activity of each aromatic HCP via the paring cycle increases, while its population retained in H-SAPO-34 usually decreases, with the methylation degree remarkably from tetramethylbenzene to hexamethylbenzene. The contents of higher methylbenzenes increase with decreasing water partial pressure, leading to the enhanced contribution of the aromatic-based cycle. The olefin-based cycle contributes to the formation of both ethene and other olefins, and the product distribution is drastically sensitive to reaction conditions. Ethene predominantly comes from the cracking of C5 and C6 species, and propene comes from C5 to C7 species. The olefin-based cycle shifts from the interconversion of C2–C7 olefins toward C2–C5 ones with increasing temperature and water partial pressure to enhance ethene formation. Under industrially relevant conditions, the conversion rate of methanol via the olefin-based cycle is 40-fold greater than that via the aromatic-based cycle (6.6 vs 0.15 s–1), and the former agrees unexpectedly with the experimental value in low-silica AlPO-34 (7.0 s–1). This work thus solves the puzzle of dominating HCPs as a function of reaction conditions in H-SAPO-34 and provides mechanistic insights into the kinetic behaviors, which are the basis for the optimization of the MTO catalyst and process.

Molecular and Serological Identification of Anaplasma marginale and Borrelia burgdorferi in Cattle and Ticks from Nuevo Leon, Northern Mexico.

Ticks and tick-borne diseases affect livestock productivity and cause significant economic losses. Therefore, surveillance of these pathogens and vectors is paramount to reducing these effects in livestock. This study aimed to identify Anaplasma marginale and Borrelia burgdorferi sensu lato in ticks collected from cattle. Molecular biology techniques were utilized to identify A. marginale for both types of samples, i.e., ticks and bovine blood. Serology of cattle using indirect immunofluorescence assay (IFA) was conducted to determine antibodies to B. burgdorferi s.l. from seven locations in Nuevo Leon, Mexico, between 2015 and 2017. From 404 bovines, 2880 ticks were collected: Rhipicephalus microplus (2391 females and 395 males), Amblyomma spp. (51 females and 42 males) and Dermacentor variabilis (1 female). Rhipicephalus microplus represented the largest specimens captured, with 96.7% within the seven study sites. PCR processed only 15% (442) of tick samples to identify A. marginale. Field genera proportions were followed to select testing tick numbers. Results showed that 9.9% (44/442) of A. maginale infected the pooled tick species, whereas the highest percent corresponded to 9.4% (38/404) in R. microplus. Regarding the molecular analysis of blood samples, 214 of 337 (63.5%) were positive for A. maginale. In each of the seven locations, at least one bovine sample tested positive for A. maginale. Borrelia burgdorferi s.l. was not found either in the ticks or serum samples. Two A.marginale DNA nucleotide sequences obtained in this study were deposited in the GenBank with the following accession numbers OR050501 cattle, and OR050500 R.microplus tick. Results of this work point to current distribution of bovine anaplasmosis in northern Mexico.

Canadian records of Branchinecta serrata Rogers, 2006 and its confusion with B. paludosa (Müller, 1788) (Branchiopoda: Anostraca: Branchinectidae), with a key to the B. paludosa species group

Abstract Branchinecta serrata Rogers, 2006 was originally thought to be limited to four localities in the central USA. We present new records of this species in prairie pools in central Canada, greatly extending its known distribution. Previous records from Canada were misidentified as the common and widespread B. paludosa (Müller, 1788). We present images emphasizing the differences between the two species, updated geochemical tolerance data, and revise the conservation status of B. serrata. Finally, we present an identification key to the Branchinecta paludosa species group.

Inconsistent relationships between area, heterogeneity and plant species richness in temperate farmed landscapes

Relationships between area, heterogeneity and species richness are fundamental concepts in ecology yet questions remain about how area and heterogeneity tradeoff (AHTO) to constrain biodiversity. Although there is growing evidence for unimodal heterogeneity diversity relationships (HDR's) and an AHTO, tests of the concept and consequences for species richness across a landscape‐scale gradient of human‐modified ecosystems are rare. Using data from a national (Wales) field survey we analysed relationships between environmental heterogeneity and plant species richness (α and γ). We used ordination to produce a composite metric of heterogeneity and compared this to commonly used metrics. We used niche hypervolumes to categorise the breadth of plant species' ecological preferences and analysed relationships between species richness, niche width and heterogeneity. The HDR was unimodal with α diversity at the smallest scale and positive with α and γ diversity (non‐linear) at the 1 km scale although in low intensity landscapes the HDR with γ diversity was unimodal. There was a unimodal relationship between habitat diversity and γ diversity. Land use intensity was unimodally related to diversity. There were significant interactions between niche width and heterogeneity. Richness of broad niche species increased with heterogeneity with flattening of the curve at higher levels. Narrow niche species were rare and mostly unresponsive. The expected decline in narrow niche species with increasing heterogeneity was not found although they did decline with land‐use intensity. Using a unique dataset, an analysis of a large‐scale mosaic of ecosystems found that the shape of the HDR varies with land use intensity, the heterogeneity metric, spatial scale, diversity type and niche width. Although heterogeneity can increase species richness, there may be tradeoffs at higher heterogeneity. A fundamental constraint on realising the benefit of heterogeneity is the low availability of narrower niche species in local species pools in modified landscapes.

Transition-Metal Catalysts for Methane Dehydroaromatization (Mo, Re, Fe): Activity, Stability, Active Sites, and Carbon Deposits

The most studied catalysts for methane dehydroaromatization (MDA)─Mo/ZSM-5─are not commercialized yet due to the rapid deactivation and insufficient activity. Catalytic systems based on Fe and Re are potential alternatives to Mo-containing zeolites. Here, we compare the catalytic performance of these catalysts as a function of metal type and its loading in ZSM-5 zeolite. The results show that the catalytic activity decreases in the order of Re/ZSM-5 > Mo/ZSM-5 > Fe/ZSM-5, while the catalyst stability decreases in the opposite order: Fe/ZSM-5 > Mo/ZSM-5 > Re/ZSM-5. The active metal species in the working catalysts were determined by operando X-ray absorption near-edge structure spectroscopy combined with mass spectrometry. We found that Re0 and Fe2+ species are the most likely active species for the catalytic dehydroaromatization of CH4 to aromatics in respective catalysts. Combining the pulse reaction technique with operando thermogravimetry analysis–mass spectrometry experiments, we demonstrate that the length of the induction period strongly correlates to the activity of the catalyst. The longer induction period of the Fe/ZSM-5 catalyst indicates the slow growth of hydrocarbon pool intermediates inside the zeolite pores and thus explains its poor catalytic performance. Finally, both the formation of hydrocarbon pool species and the activity of Fe/ZSM-5 can be improved by increasing the Fe loading, reaction pressure, and space velocity.

Variant analysis of grain size related genes in the genus Sorghum

Grain size and weight are two of the most important determinants of crop yield. Key genes associated with the grain size and weight have been identified in major crops. However, studies on the genetic basis of the grain size and weight related genes in wild Sorghum are limited. In this study, we analysed the variation of grain size related genes using variant analysis of 15 accessions across one cultivated and six tertiary gene pool species representing the five subgenera of Sorghum. A wide variation in grain size related parameters was observed. The highest grain weight, width, and thickness was observed for the accession S. bicolor (L.) Moench 314,746, while the highest grain length was observed for the accession S. macrospermum E.D. Garber 302,367. The wild sorghum species exhibited high morphological diversity. The six candidate genes related to grain size, Sobic.001G335800 (qGW7/GL7), Sobic.001G341700 (GS3), Sobic.002G257900 (GW8), Sobic.003G035400 (GW5/qSW5), Sobic.004G107300 (GW2), and Sobic.009G053600 (GS5) showed polymorphism in the coding sequence regions including variants generating premature stop codons. These variants might contribute to the observed variation in grain size and weight. The tertiary wild sorghum species may be a useful source of genes for understanding and engineering grain size in sorghum and other cereals.

Plastome-based phylogeny and biogeography of Lactuca L. (Asteraceae) support revised lettuce gene pool categories.

This study generated and analyzed complete plastome and internal transcribed spacer (ITS) data of 46 Lactuca species, 13 African endemic (AE) Lactuca species, and 15 species from eight related genera in Lactucinae. The new plastome and nuclear ITS sequences were then used to reconstruct the phylogenetic relationships of Lactuca species. The whole-plastome data were used to estimate divergence time and ancestral area reconstruction of the identified major Lactuca lineages. The results showed that Lactuca species are generally similar in plastome size, Guanine and Cytosine (GC) content, gene structure, and categories, although crop lettuce (Lactuca sativa L.) and its gene pool relatives were found to have one unique pseudogene (ψ ndhF), and accD, atpF, cemA, clpP, and rpl22 showed signs of positive selection. Our phylogenomic analysis demonstrated that Lactuca is monophyletic after excluding Lactuca alatipes Collett and Hemsl and AE Lactuca species. AE Lactuca species are morphologically distinct from core Lactuca lineage and need to be excluded from Lactua. The core Lactuca species most likely originated from Asia-Temperate W ~6.82 Mya and then dispersed globally and formed nine clades. Finally, the lettuce gene pool concept was amended according to the phylogenetic and historical biogeographic analyses. This study revised the circumscription of Lactuca, revealed robust phylogenetic relationships within the genus, and provided insights into Lactucinae phylogeny. The lettuce gene pool species could be used as potential genetic resources for lettuce breeding.

Insight into induction period of methanol conversion reaction: Reactivity of ethene-precursors over H-ZSM-5 zeolite is independent of Brϕnsted acid site density

A series of H-ZSM-5 (TZ-m, m represents different Si/Al ratios) has been prepared and their Methanol to Olefin (MTO) performance are investigated. By adjusting the catalyst weight of H-ZSM-5 loaded in the pulse micro-reactor, the total Brϕnsted acid sites (BAS) amount of TZ-m catalysts is unified. The resultant similar methanol conversion (∼24 %) over different TZ-m zeolites confirms that the MTO reaction is dominantly catalyzed by BAS. Nevertheless, the BAS density considerably influences the reaction pathways; more condensed BAS enhances the relative propagation of aromatic-based cycle to alkene-based cycle, and vice versa. However, isotopic co-feeding and switching experiment reveals that the reactivity of aromatic hydrocarbon pool (HCP) species, which has been considered as main ethene precursors, is almost independent of acid site density. Although large amounts of aromatics are generated via hydrogen transfer reactions on the sample with high acid site density, most of the confined aromatics function as coke precursors instead of active HCPs. The accumulation of such confined aromatics in zeolite channels further limits olefins mobility and their access to BAS, leading to decreased reactivity of alkene HCPs on high acid site-density samples.

Coking and decoking chemistry for resource utilization of polycyclic aromatic hydrocarbons (PAHs) and low-carbon process

Low-carbon process for resource utilization of polycyclic aromatic hydrocarbons (PAHs) in zeolite-catalyzed processes, geared to carbon neutrality-a prominent trend throughout human activities, has been bottlenecked by the lack of a complete mechanistic understanding of coking and decoking chemistry, involving the speciation and molecular evolution of PAHs, the plethora of which causes catalyst deactivation and forces regeneration, rendering significant CO2 emission. Herein, by exploiting the high-resolution matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry (MALDI FT-ICR MS), we unveil the missing fingerprints of the mechanistic pathways for both formation and decomposition of cross-linked cage-passing PAHs for SAPO-34-catalyzed, industrially relevant methanol-to-olefins (MTO) as a model reaction. Notable is the molecule-resolved symmetrical signature: their speciation originates exclusively from the direct coupling of in-cage hydrocarbon pool (HCP) species, whereas water-promoted decomposition of cage-passing PAHs initiates with selective cracking of inter-cage local structures at 8-rings followed by deep aromatic steam reforming. Molecular deciphering the reversibly dynamic evolution trajectory (fate) of full-spectrum aromatic hydrocarbons and fulfilling the real-time quantitative carbon resource footprints advance the fundamental knowledge of deactivation and regeneration phenomena (decay and recovery motifs of autocatalysis) and disclose the underlying mechanisms of especially the chemistry of coking and decoking in zeolite catalysis. The positive yet divergent roles of water in these two processes are disentangled. These unprecedented insights ultimately lead us to a steam regeneration strategy with valuable CO and H2 as main products, negligible CO2 emission in steam reforming and full catalyst activity recovery, which further proves feasible in other important chemical processes, promising to be a sustainable and potent approach that contributes to carbon-neutral chemical industry.

Illustrating the overall reaction network of the synthesis-gas-to-hydrocarbons process over iron-zeolite bifunctional catalysis

Since its discovery in the early 20 th century, Fischer-Tropsch synthesis (FTS) has opened a path, as an alternative to crude oil, to produce fuels and chemicals. When classical FTS catalysts are combined with acidic zeolites, the scope of this gas-phase polymerization can be narrowed, thus maximizing the production of value-added commodities and eliminating energy-consuming separation steps. However, from a mechanistic standpoint, even now, little is known about the role of the different reaction intermediates. Here, we present a comprehensive, in-depth, mechanistic investigation using solid-state NMR spectroscopy and well-designed control experiments on combining a classical Fe-based FTS catalyst and zeolites with different topologies to establish the impact of “co-catalytic” key organic carbon-based reaction intermediates, including carbonylated/oxygenated species (ester/ketone/alcohol/ether/epoxide/ketene). Consequently, this work provides experimental evidence supporting the “co-existence” of oxygenate (cf. surface-enol and CO-insertion) mechanisms (together with the traditional carbide-based FTS mechanism). The significance of “supramolecular reactive centers” within zeolite and host-guest chemistry has also been illuminated. • Zeolite topologies altered preferential hydrocarbon product selectivities • Mobility-based solid-state NMR identified crucial carbon-based reaction intermediates • Co-involvement of oxygenated/carbonylated species is evaluated during syngas conversion • Significance of inorganic-organic supramolecular reaction centers has been established To alleviate pressure from increased environmental regulations over carbon emissions, the direct hydrogenation of CO/CO 2 to diverse hydrocarbons over bifunctional catalysts is a priority research topic worldwide. Identifying new catalytic routes to valorize C1-feedstock is a key to combating climate change, whereby Fischer-Tropsch synthesis (FTS) over bifunctional metal-zeolite catalysts offers elegant solutions to diversify global fuel/chemical supply. However, their overall reaction network to deliver preferential final product selectivity remains elusive and controversial. Through this work, we achieve this goal by identifying key carbon-based reaction intermediates and establishing a full reaction network of the synthesis-gas-to-hydrocarbons process over Fe 2 O 3 @KO 2 /zeolite catalyst. This established structure-reactivity relationship can upgrade the current FTS process and improve the fundamental understanding of bifunctional catalysis. Identifying “descriptor”-style carbon-based reaction intermediates is significant in upgrading the current state of metal-zeolite bifunctional “cascade” catalysis. In this work, four different product selectivities (short olefins, light paraffins, long-chain hydrocarbons, and aromatics) were observed during the syngas-to-hydrocarbon process (Fischer-Tropsch type) over potassium superoxide-doped iron oxide/zeolite-based bifunctional catalysts. Here, we demonstrate that the zeolite topology and “co-catalytic” hybrid supramolecular reactive centers (i.e., organic hydrocarbons pool species trapped by the inorganic zeolite) regulate the reaction mechanism and the final product selectivity.

Exploration of incompatible crosses in plants for novel and useful variations

AbstractCrop improvement through pre‐breeding utilizes elite lines, germplasm and species of compatible gene pools, but crossing and characterizing the derivatives between incompatible species, especially distant genera or species, is realized to introduce de novo variations that are heritable, stable and especially economically contributing. This is a novel approach to introduce large‐scale de novo variations in crops that can be applied to widening of the genetic base. It helps to introduce heritable and agronomical variations that can be evolved in a short time for use in trait specific breeding programmes. In crosses between incompatible species many times F1 are delusive appearing like maternal parent. But large variations in F2 are observed due to genetic changes that include partial or complete elimination of the genome from the paternal parent, reshuffling of the maternal genome leading to several changes that are translated to phenotype. Genome, transcriptome and epigenetic reprogramming is responsible for the above genetic changes. Crossing two distant species can be used as an additional tool in plant breeding.