bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Functional Switch Between Asperfumene and Fusicoccadiene Synthase and Entrance to Asperfumene Biosynthesis through a Vicinal Deprotonation‐Reprotonation Process
Authors: Liu Jing‐Yuan , Lin Fu‐Long , Taizoumbe Kizerbo A. , Lv Jian‐Ming , Wang Yong‐Heng , Wang Gao‐Qian , Chen Guo‐Dong , Yao Xin‐Sheng , Hu Dan , Gao Hao , Dickschat Jeroen S. 
Published: July 2024

AbstractThe diterpene synthase AfAS was identified from Aspergillus fumigatiaffinis. Its amino acid sequence and—according to a structural model—active site architecture are highly similar to those of the fusicocca‐2,10(14)‐diene synthase PaFS, but AfAS produces a structurally much more complex diterpene with a novel 6–5–5–5 tetracyclic skeleton called asperfumene. The cyclisation mechanism of AfAS was elucidated through isotopic labelling experiments and DFT calculations. The reaction cascade proceeds in its initial steps through similar intermediates as for the PaFS cascade, but then diverges through an unusual vicinal deprotonation‐reprotonation process that triggers a skeletal rearrangement at the entrance to the steps leading to the unique asperfumene skeleton. The structural model revealed only one major difference between the active sites: The PaFS residue F65 is substituted by I65 in AfAS. Intriguingly, site‐directed mutagenesis experiments with both diterpene synthases revealed that position 65 serves as a bidirectional functional switch for the biosynthesis of tetracyclic asperfumene versus structurally less complex diterpenes.
Enhancing Effect of Fullerene Guest and Counterion on the Structural Stability and Electrical Conductivity of Octahedral Metallo‐Supramolecular Cages
Authors: Lu Shuai , Zhang Ziang , Zhu Yiying , Tao Ye , Lin Quanjie , Zhang Qian , Lv Xin , Hua Lei , Chen Zhi , Wang Heng , Zhuang Gui‐Lin , Zhang Qian‐Chong , Guo Cunlan , Li Xiaopeng , Yu Xiujun 
Published: July 2024

AbstractMetallo‐supramolecular cages have garnered tremendous attention for their diverse yet molecular‐level precision structures. However, the physical properties of these supramolecular ensembles, which are of potential significance in molecular electronics, remain largely unexplored. We herein constructed a series of octahedral metallo‐cages and cage‐fullerene complexes with notably enhanced structural stability. As such, we could systematically evaluate the electrical conductivity of these ensembles at both the single‐molecule level and aggregated bulk state (as well‐defined films). Our findings reveal that counteranions and fullerene guests play a pivotal role in determining the electrical conductivity of the aggregated state, while such effects are less significant for single‐molecule conductance. Both the counteranions and fullerenes effectively tune the electronic structures and packing density of metallo‐supramolecular assemblies, and facilitate efficient charge transfer between the cage hosts and fullerenes, resulting in a notable one order of magnitude increase in the electrical conductivity of the aggregated state.
Coordination Engineering of Fe‐Centered Catalysts for Superior Li−S Battery Performance
Authors: Yuan Hao , Yang Jing , Zhang Yong‐Wei 
Published: July 2024

AbstractIron‐nitrogen functionalized graphene has emerged as a promising cathode host for rechargeable lithium‐sulfur batteries (RLSBs) due to its affordability and enhanced battery performance. To optimize its catalytical efficiency, we propose a novel approach involving coordination engineering. Our investigation spans a plethora of catalysts with varied coordination environments, focusing on elements B, C, N and O. We revealed that Fe−C4 and Fe−B2C2−h are particularly effective for promoting Li2S oxidation, whereas Fe‐N4 excels in catalyzing the sulfur reduction reaction (SRR). Importantly, our study identified specific descriptors – namely, the Integrated Crystal Orbital Hamilton Population (ICOHP) and the bond length between Fe and S in Li2S adsorbed state – as the most effective predictive descriptors for Li2S oxidation barriers. Meanwhile, Li2S adsorption energy emerges as a reliable descriptor for assessing the SRR barrier. These identified descriptors are expected to be instrumental in rapidly identifying promising cathode hosts across various metal‐centered systems with diverse coordination environments. Our findings not only offer valuable insights into the role of coordination environment, but also present an effective path for rapidly identifying high performance catalysts for RLSBs, enabling the acceleration of advanced RLSBs development.
Enzymatic Functionalization of RNA Oligonucleotides by Terminal Uridylyl Transferase Using Fluorescent and Clickable Nucleotide Analogs
Authors: Dutta Swagata , Srivatsan Seergazhi G. 
Published: July 2024

AbstractWe report a systematic study on controlling the enzyme activity of a terminal uridylyl transferase (TUTase) called SpCID1, which provides methods to effect site‐specific incorporation of a single modified nucleotide analog at the 3′‐end of an RNA oligonucleotide (ON). Responsive heterocycle‐modified fluorescent UTP probes that are useful in analyzing non‐canonical nucleic acid structures and azide‐ and alkyne‐modified UTP analogs that are compatible for chemoenzymatic functionalization were used as study systems. In the first strategy, we balanced the concentration of essential metal ion cofactors (Mg2+ and Mn2+ ions) to restrict the processivity of the enzyme, which gave a very good control on the incorporation of clickable nucleotide analogs. In the second approach, borate that complexes with 2′ and 3′ oxygen atoms of a ribose sugar was used as a reversibly binding chelator to block repeated addition of nucleotide analogs. Notably, in the presence of heterocycle‐modified fluorescent UTPs, we obtained single‐nucleotide incorporated RNA products in reasonable yields, while with clickable nucleotides yields were very good. Further, 3′‐end azide‐ and alkyne‐labeled RNA ONs were post‐enzymatically functionalized by CuAAC and SPAAC reactions with fluorescent probes. These strategies broaden the scope of TUTase in site‐specifically installing modifications of different types onto RNA for various applications.
Enzyme‐Powered, Label‐Free DNA Walker for Uracil‐DNA Glycosylase Detection at Single‐Cell Level
Authors: Li Wei , Wang Shuaijing , Zong Haotian , Li Jiayue , Zhou Yi , Wang Zhenguang 
Published: July 2024

AbstractUracil‐DNA glycosylase (UDG) plays a crucial role in the removal of damaged uracil bases, thereby upholding genetic stability and integrity. An enzyme‐powered, label‐free DNA walker was devised for UDG activity detection. Initially, a label‐free DNA track, incorporating a gold nanoparticle (AuNP), multiple hairpin structures, and various swing arms, was engineered for walking mechanism. The hairpin structure was meticulously crafted to include a G‐quadruplex sequence, enabling the generation of a label‐free fluorescence signal. The swing arm remained inert in the absence of UDG, but became activated upon the introduction of UDG, thereby initiating the enzyme‐powered walking process and generating significant dissociative G‐quadruplex sequences. By integrating a selective fluorescent dye into the design, an enhanced label‐free fluorescence response was achieved. The proposed DNA walker presented a direct and label‐free approach for UDG detection, demonstrating exceptional sensitivity with a detection limit of 0.00004 U/mL. Using the uracil glycosylase inhibitor (UGI) as an inhibitory model, inhibitor assay was conducted with satisfactory precision. Furthermore, successful analysis of cellular UDG at the single‐cell level was accomplished. Consequently, the developed DNA walker serves as a label‐free, selective, and sensitive tool for UDG activity assessment, showing great potential for applications in disease diagnosis, inhibitor screening, and biomedical investigations.
Synthesis, Antimicrobial, Molecular Docking Against Bacterial and Fungal Proteins and In Silico Studies of Glucopyranoside Derivatives as Potent Antimicrobial Agents
Authors: Islam Mazherul , Hossain Ahad , Yamari Imane , Abchir Oussama , Chtita Samir , Ali Ferdausi , Kawsar Sarkar M. A. 
Published: July 2024

AbstractCarbohydrate derivatives play a crucial roles in biochemical and medicinal research, especially in the fields of chemistry and biochemistry. From this perspective, the present study was designed to explore the synthesis of methyl α‐D‐glucopyranoside derivatives (1–8), focusing on their efficacy against bacterial and fungal inhibition. The structure of the synthesized compounds was ascertained using FTIR, 1H‐NMR, 13C‐NMR, mass and elemental analyses. Antimicrobial screening revealed strong antifungal properties, with compound 7 exhibiting minimum inhibitory concentrations (MICs) ranging from 16–32 μg/L and minimum bactericidal concentrations (MBCs) ranging from 64–128 μg/L. Incorporating decanoyl acyl groups at C‐2 and C‐3 of (7) significantly improved the efficacy against bacteria and fungi. Structure‐activity relationship (SAR) analysis indicated that adding nonanoyl and decanoyl groups to the ribose moiety enhanced potency against both bacterial and fungal strains. Computational methods, including molecular docking, density functional theory (DFT), Petra, Osiris, Molinspiration (POM) evaluation, and molecular dynamics (MD) simulations, were used to assess the efficacy of these derivatives. Compounds 6 and 7, which presented nonanoyl and decanoyl substituents, demonstrated greater efficacy. In addition, DFT studies identified compound 8 as possessing ideal electronic properties. Molecular docking revealed that compound 8 exhibits exceptional binding affinities to bacterial proteins, conferring potent antibacterial and antifungal activities. In addition, pharmacokinetic optimization via POM analysis highlighted compounds 1 and 2 as promising bioavailable drugs with minimal toxicity. Molecular dynamics simulations confirmed the stability of the 2‐S. aureus complex, revealing the therapeutic potential of compounds 2 and 8. Future experiments are required to validate their efficacy for pharmaceutical development. The integration of in vitro and in silico methods, including DFT anchoring dynamics and molecular dynamics simulations, provides a solid framework for the advancement of effective anti‐infective drugs.
Management of extensive portal vein thrombosis via thrombolysis and thrombectomy without underlying liver disease: A case report
Authors: Gul Mohammadshah Isam , Umer Waseem , Nawaz Ahmed Daniyal , Elhissi Mohammad J. H. , Zahid Muhammad 
Published: July 2024

Key Clinical MessagePortal vein thrombosis (PVT) is a rare condition, particularly in non‐cirrhotic patients. Anticoagulation remains the mainstay of the treatment. Extensive PVT can lead to variceal bleeding, ascites, bowel ischemia, and hypersplenism. The role of thrombolysis and thrombectomy in these patients remains unclear. However, there is evidence that local thrombolysis and thrombectomy should be considered in those who remain symptomatic on anticoagulation and are at risk of complications with acute PVT.
Multiple intracranial tuberculomas in an elderly patient: A central nervous system tuberculosis case in the emergency department
Authors: Farrokhnia Mehrdad , Mirkamali Hanieh , Alizadeh Seyed Danial , Rezaei Zadeh Rukerd Mohammad 
Published: July 2024

Key Clinical MessageA 67‐year‐old male presented to the emergency department with a 7‐day history of fever, malaise, myalgia, headache, and a seizure episode. Physical examination showed stable vital signs but a fever. Laboratory tests indicated leukocytosis, anemia, thrombocytosis, and elevated inflammatory markers. Imaging revealed multiple intracranial lesions, and cerebrospinal fluid analysis confirmed the presence of acid‐fast bacilli. The patient responded well to anti‐tuberculosis therapy, showing significant clinical improvement within 8 weeks.
Achieving Non‐Interfacial Blocking Zinc Ion Transport Based on MOF Derived Manganese Oxides and Amorphous Carbon Hybrid Materials
Authors: Jiang Siyu , Han Wenjuan , Fang Luan , Zhang Shu , Xue Xiangxin , Nie Ping , Liu Bo , Zhao Cuimei , Lu Ming , Chang Limin 
Published: July 2024

AbstractHow to coordinate electron and ion transport behavior across scales and interfaces within ion battery electrodes? The exponential increase in surface area observed in nanoscale electrode materials results in an incomprehensibly vast spatial interval. Herein, to address the problems of volume expansion, dissolution of cathode material, and the charge accumulation problem existing in manganiferous materials for zinc ion batteries, metal organic framework is utilized to form the architecture of non‐interfacial blocking ~10 nm Mn2O3 nanoparticles and amorphous carbon hybrid electrode materials, demonstrating a high specific capacity of 361 mAh g−1 (0.1 A g−1), and excellent cycle stability of 105 mAh g−1 after 2000 cycles under 1 A g−1. The uniform and non‐separated disposition of Mn and C atoms constitutes an interconnected network with high electronic and ionic conductivity, minimizing issues like structural collapse and volume expansion of the electrode material during cycling. The cooperative insert mechanism of H+ and Zn2+ are analyzed via ex‐situ XRD and in‐situ Raman tests. The model battery is assembled to present practical possibilities. The results indicate that MOF‐derived carbonization provides an effective strategy for exploring Mn‐based electrode materials with high ion and electron transport capacity.
Photothermal Effect and Fenton‐Like Oxidation for Synergistic Removal of Fluoroquinolones Antibiotics under Near‐Neutral Conditions
Authors: Jiao Lanya , Meng Jiao , Wang Shujun , Sun Xuan 
Published: July 2024

AbstractDefect‐enriched mesoporous CuO nanosheets (NSs) were constructed to investigate the cooperative photo‐Fenton and photothermal‐Fenton catalysis on degradation of fluoroquinolones (FQ) antibiotics. The oxygen vacancies provide abundant active sites to bind the substrates and inhibit charge recombination, by all means to enhance Fenton‐like activity. Two disparate spectral selective functions of photoexcitation and photothermal conversion were achieved on CuO NS, which to promote the Fenton activity synergistically. Visible light induced photoexcitation to facilitate the generation of Cu+ and ⋅OH, while near‐infrared light converted into heat to promote charge separation and accelerate medium transport. Ultimately, as a unitary catalyst system, the CuO NS integrated the Lewis acid catalysis, Fenton‐like catalysis and photothermal catalysis that rapidly and sustainably degraded antibiotics under near‐neutral conditions.
Isolation and characterization of synthesis intermediates and side products in hexahydrocannabiphorol
Authors: Schirmer Willi , Gjuroski Ilche , Vermathen Martina , Furrer Julien , Schürch Stefan , Weinmann Wolfgang 
Published: July 2024

AbstractAfter the Swiss ban of hexahydrocannabinol (HHC) in March 2023, other semisynthetic dibenzopyran cannabinoids emerged on the Swiss gray market. Hexahydrocannabiphorol (HHCP) was the most prominent of them due to its potent cannabimimetic effects, as anecdotal reports from recreational users suggest. In October 2023, a class wide ban of dibenzopyran cannabinoids was introduced in Switzerland to prevent new similar substances from entering the drug market. Various vendors in online shops claim that HHCP is made from CBD, even though they possess different alkyl chain lengths. An HHCP sample was analyzed by gas chromatography coupled to mass spectrometry (GC‐MS), showing that a mixture of molecules with the same or a similar molecular mass as HHCP was present. Six different substances could be isolated from this sample using column chromatography. Four phenols ((9R)‐HHCP, iso‐HHCP, cis‐HHCP, and abn‐HHCP) and two ketones (possible intermediates to (9R)‐HHCP and abn‐HHCP) were identified by various nuclear magnetic resonance spectroscopy (NMR) techniques. (9S)‐HHCP was obtained in an impure fraction. In addition, a fraction was obtained that showed characteristic molecular and fragment ions consistent with bisalkylated products from the synthesis of similar compounds. The presence of abnormal cannabinoids (abn‐HHCP) and bisalkylated cannabinoids is a confirmation that this sample was produced purely synthetically as initially suspected, as these compounds have not been reported in Cannabis. Chiral derivatization of the phenols with Mosher acid chlorides showed that only iso‐HHCP was present as a scalemic mixture, indicating a good stereocontrol of this synthetic procedure.
The analysis of methylamphetamine and para‐hydroxy‐methylamphetamine in post‐mortem hair samples using liquid chromatography–tandem mass spectrometry
Authors: Mantinieks Dylan , Drummer Olaf H. , Schumann Jennifer , Gerostamoulos Dimitri 
Published: July 2024

AbstractExternal contamination is a well‐recognized limitation of hair analysis for drugs of abuse like methylamphetamine (MA), and there are no guidelines regarding the analysis of specific metabolites of MA to assist interpretation. We developed an analytical method to detect MA, amphetamine (AMP), and para‐hydroxy‐methylamphetamine (p‐OH‐MA) in hair and present their concentrations among a cohort of deceased persons positive for MA in blood (n = 63). Hair samples (≤ 3 cm) were washed with dichloromethane and water prior to extraction using a methanolic micro‐pulverization. The reconstituted hair extracts were separated on a UCT Selectra® Aqueous C18 HPLC Column (100 × 2.1 mm, 3 μm) by gradient elution and detected using a Sciex Triple Quad 6500+ system. Validation was satisfactory, and the lower limits of quantitation were 0.01 ng/mg for MA and AMP and 0.001 ng/mg for p‐OH‐MA. The median hair concentrations of MA, AMP, and p‐OH‐MA were 13 ng/mg (range = 0.015–49; n = 51), 1.1 ng/mg (range = 0.018–44; n = 60), and 0.020 ng/mg (range = 0.0012–0.38, n = 62), respectively. These concentrations in hair were strongly positively correlated (r = .7202 to .8641, p < .001), suggesting similar modes of incorporation. Moreover, the wash/hair ratios were indicative of external contamination, especially among the soiled group of hair samples. Therefore, further studies are necessary to determine concentrations of p‐OH‐MA in living MA users and confirm if this metabolite constitutes a potential marker of MA consumption.
Growth–defense trade‐offs promote habitat isolation between recently‐diverged species
Authors: Harenčár Julia G. , Salazar‐Amoretti Diego , García‐Robledo Carlos , Kay Kathleen M. 
Published: July 2024

AbstractTrade‐offs are crucial for species divergence and reproductive isolation. Trade‐offs between investment in growth versus defense against herbivores are implicated in tropical forest diversity. Empirically exploring the role of growth–defense trade‐offs in closely related species' reproductive isolation can clarify the eco‐evolutionary dynamics through which growth–defense trade‐offs contribute to diversity. Costus villosissimus and C. allenii are recently diverged, interfertile, and partially sympatric neotropical understory plant species primarily isolated by divergent habitat adaptation. This divergent adaptation involves differences in growth rate, which may constrain investment in defense. Here, we investigate growth–defense trade‐offs and how they relate to the divergent habitat adaptation that isolates these species. We characterize leaf toughness and chemistry, evaluate the feeding preferences of primary beetle herbivores in controlled trials and field‐based experiments, and investigate natural herbivory patterns. We find clear trade‐offs between growth and defense: slower‐growing C. allenii has tougher leaves and higher defensive chemical concentrations than faster‐growing C. villosissimus. Costus villosissimus has rapid growth‐based drought avoidance, enabling growth in drier habitats with few specialist herbivores. Therefore, growth–defense trade‐offs mediate synergistic biotic and abiotic selection, causing the divergent habitat adaptation that prevents most interspecific mating between C. villosissimus and C. allenii. Our findings advance understanding of ecological speciation by highlighting the interplay of biotic and abiotic selection that dictates the outcome of trade‐offs.
Assessing the performance of short 18S rDNA markers for environmental DNA metabarcoding of marine protists
Authors: Zimmermann Heike H. , Harðardóttir Sara , Ribeiro Sofia 
Published: July 2024

AbstractMarine protists are globally distributed and sensitive to environmental conditions, which makes them a focal group when studying the effects of climate change on biodiversity and ocean health. However, they are a highly diverse group with varying evolutionary histories and morphologies and widely variable preservation potential in the fossil record. Thus, their past diversity and composition are poorly known. Paleogenetics, which relies, among other approaches, on DNA metabarcoding of sedimentary ancient DNA (sedaDNA), provides a promising avenue to explore the past history and responses of marine protists to global change. Choosing the right marker for sedaDNA studies is critical, striking a balance between marker length and taxonomic resolution. While marker guides exist for modern environmental DNA surveys, a thorough assessment of existing short markers for sedaDNA studies targeting protists is lacking. In this study, we report on a comparison of in silico PCR for eight short 18S rDNA markers, including one from the Tara Oceans initiative and a longer marker commonly used in modern marine eDNA studies. We analyze their taxonomic coverage and resolution, taxonomic overlap and uniqueness between markers, co‐amplification of non‐protist taxa, and amplicon size differences across taxonomic groups. Additionally, we provide a detailed analysis of diatoms, dinoflagellates, haptophytes, and chlorophytes. Our study is aimed at supporting project‐specific marker choices for characterizing protist composition and diversity. While we focus on marine protists, our results are applicable to other aquatic and terrestrial environments.
Potentiometric determination of nitrazepam in pharmaceutical dosage form and spiked plasma using a novel modified carbon paste electrode
Authors: Azab Marwa M. , Rizk Mohamed , Mohamed Omaima M. , Farag Amir Shaaban 
Published: July 2024

AbstractA newly prepared solid contact ion selective electrode based on polyvinyl chloride membrane has been optimized and developed for determining nitrazepam in its pure form and synthetically prepared tablet dosage form. The proposed electrode was fabricated based on zeolite modified carbon paste electrode as a solid contact acting as a support for the membrane of PVC containing the ion complex of nitrazepam‐tetraphenyl borate as an electroactive material, and the plasticizer dibutyl phthalate. By improving the composition, the potentiometric properties were further enhanced, and the sensor achieved a Nernstian slope of 60.89 mV dec−1. The sensor was effective for detecting nitrazepam in the concentration range of 1.0×10−7 to 1.0×10−2 M, with a detection limit of 4.7×10−8 M. The sensor demonstrated excellent reversibility and reproducibility with a fast response time and application over a wide pH range. The developed electrode showed no significant effect when tested with various interfering species. It is successfully applied for accurate determination of nitrazepam in pure form, synthetically prepared tablet and spiked human plasma. The developed technique was validated and demonstrated high accuracy and precision. When compared statistically with the official method, there were no significant differences observed.