Relative Configuration Research Articles

Anthoteibinenes F–Q: New Sesquiterpenes from the Irish Deep-Sea Coral Anthothela grandiflora

New technology has opened opportunities for research and exploration of deep-water ecosystems, highlighting deep-sea coral reefs as a rich source of novel bioactive natural products. During our ongoing investigation of the chemodiversity of the Irish deep sea and the soft coral Anthothela grandiflora, we report 12 unreported cadinene-like functionalized sesquiterpenes, anthoteibinenes F–Q. The metabolites were isolated using both bioassay- and 1H NMR-guided approaches. One-/two-dimensional NMR spectroscopy and high-resolution mass spectrometry were used for structure elucidation, while a combination of NOESY NMR experiments, GIAO NMR calculations coupled with DP4+ probabilities measures, and ECD comparisons were incorporated to propose relative and absolute configurations of the anthoteibinenes. The metabolites were screened against the Respiratory Syncytial Virus (RSV), ESKAPE pathogens, five Candida albicans strains, and one strain of C. auris.

Precise Synthesis of Complex Si-Si Molecular Frameworks.

In this Perspective, we highlight the emergence of target-oriented syntheses of complex molecules composed of Si-Si (oligosilanes) rather than C-C bonds. Saturated oligosilanes structurally resemble alkanes with respect to a tetrahedral geometry, a preference for a staggered conformation in linear chains, the ability to form stable small rings, and tetrahedral stereochemistry at asymmetrically functionalized Si centers. There are also critical differences, for example, differences in multiple bonding and the ability to form penta- and hexacoordinated structures, that mean that chemical reactivity and, in particular, rules for stereoselective synthesis do not cleanly translate from carbon to silicon. This Perspective will discuss recent achievements in the precise, controlled synthesis of complex molecules comprised mainly of Si-Si bonds and highlight the mechanistic insights enabling increased molecular complexity. New tools, such as electrochemical and catalytic reactions, will be discussed as well as the problem of controlling relative configuration in molecules containing multiple stereogenic-at-silicon centers. These synthetic achievements facilitate the discovery of new properties, including insight into light absorption, conformation, and mechanical properties.

Queering Contemporary Comedy: FX's What We Do in the Shadows and the Mediation of Nonnormative Gender and Sexual Identities

Utilizing queer theory, a textual analysis of 50 episodes of the FX horror-comedy series What We Do in the Shadows (2019–) resulted in three overarching themes: (1) representation of different forms of queerness and open expression of character identities, (2) normalization of queer identity and resistance to homophobia, and (3) inclusivity of relational configuration beyond queer-based narratives. Findings demonstrate the series promotes a queer perspective in addition to outright support for nonheteronormative characters. This reading of its dialogic and visual text adds to the literature on the positive media treatment of LGBTQ+ communities and how popular media texts serve as conduits of resistance to normative heterosexuality. Research in this vein is especially cogent and relevant given increasing antitransgender and intersex legislation that marks the U.S. political environment in recent years.

Bioactive secondary metabolites from Talaromyces rugulosus GIZ45-A37 and their anti-inflammatory activity

As part of our plan to discover new bioactive ingredients from entomophagous fungi, a new macrolide compound, talarolide (1), and a new bioactive natural product, talarenal (2), with two known compounds, WF-3681 methy ester (3) and aspergillumarin A (4) were isolated from an insect derived strain Talaromyces rugulosus GIZ45-A37. The structures were determined based on extensive comprehensive spectroscopic (NMR and HR-ESI-MS) analyses and compared with literature values. The relative configuration of 1 was defined by DFT-NMR chemical shift calculations and subsequent DP4/DP4+ probability methods. Compounds 1 and 2 showed inhibitory effect on IL-6 production at 10 and 20 μM in LPS-stimulated beas-2b cells, indicating their potential anti-inflammatory activity.

Eremophilane- and Acorane-Type Sesquiterpenes from the Deep-Sea Cold-Seep-Derived Fungus Furcasterigmium furcatum CS-280 Cultured in the Presence of Autoclaved Pseudomonas aeruginosa QDIO-4.

Six new sesquiterpenes, including four eremophilane derivatives fureremophilanes A-D (1-4) and two acorane analogues furacoranes A and B (5 and 6), were characterized from the culture extract of the cold-seep derived fungus Furcasterigmium furcatum CS-280 co-cultured with autoclaved Pseudomonas aeruginosa QDIO-4. All the six compounds were highly oxygenated especially 2 and 3 with infrequent epoxyethane and tetrahydrofuran ring systems. The structures of 1-6 were established on the basis of detailed interpretation of 1D and 2D NMR and MS data. Their relative and absolute configurations were assigned by a combination of NOESY and single crystal X-ray crystallographic analysis, and by time-dependent density functional (TDDFT) ECD calculations as well. All compounds were tested the anti-inflammatory activity against human COX-2 protein, among which, compounds 2 and 3 displayed activities with IC50 values 123.00 µM and 93.45 µM, respectively. The interaction mechanism was interpreted by molecular docking.

Lamellodysideol, a new flexible marine norditerpenoid from the Indonesian marine sponge Lamellodysidea herbacea

One new acyclic norditerpenoid, lamellodysideol (1) was isolated from the Indonesian marine sponge Lamellodysidea herbacea together with known phytol (2). The structure of 1 was determined on the basis of spectral evidence and by comparison with known related molecules including optical rotation data. The relative configurations of 1d and 2b were proposed using quantum chemical calculation of NMR chemical shifts at DFT levels. In addition, the relative configuration of 2b was also supported by Newman’s rule of six and confirmed through Hehre’s protocol. Compounds 1d and 2b showed toxicity against NBT-T2 cells assay at 10 µg/mL.

Stereo‐ and Chemoselective Enrichment of sp3 Character in Post‐Ugi Morpholines

AbstractWe conducted a systematic study on synthesis and modification of morpholine core using Ugi adducts derived from propiolic acid and glycolaldehyde dimer. The assembly step involved triphenylphosphine‐promoted 6‐exo‐dig umpolung oxa‐Michael cyclization of Ugi‐derived hydroxypropargylamides yielding 2‐methylenemorpholin‐3‐one derivatives. Subsequent heterogeneous catalytic hydrogenation of the exocyclic double bond proceeded in a highly diastereoselective fashion establishing a relative cis configuration in the resulting sp3‐enriched morpholinone scaffold. Finally, chemoselective amide reduction with lithium aluminum hydride (LAH) allowed to obtain fully saturated morpholines while leaving the more sterically hindered exocyclic amide moiety intact. Taken together these findings outline the strategy for controlled reduction of the inherent rigidity of post‐Ugi scaffolds.

Economic Cooperation Between the European Union and Brazil

The article is based on forecasts of international think tanks and on the studies made by foreign and Russian authors. The features of economic interaction between the European Union and Brazil are traced and characterized. Such issues as the “EU's ‒ Brazil“ strategic partnership, bilateral trade and investment cooperation, the importance of the climate agenda and the energy transition are examined. As well, the author tries to foresee possible development options for the cooperation between the EU and the South American Giant in the short and medium term. It was concluded that, in the new context of the world order, the European Union has to adapt to the strengthening position of the Global South in which Brazil will play the weighty role. The article shows that Brazil retains its role as a key link in European inter-regionalism and participates in three mechanisms of EU interaction with Latin America: interregional, subregional and bilateral. After a period of stagnation in strategic EU‒LAC partnership, in the third decade of the XXI century the European Union focused on Brazil as its main South American partner and intermediary on such issues as climate change and energy transition. The study aims to show, using the example of the EU and Brazil, the configuration of relations between the former and new centers of power in the modern context of the global world order, characteristics of which is uncertainty and increased competition in access to critical natural resources and technologies. The European Union, probably, will use the future ratification of the trade agreement with Mercosur as an element of pressure on Brazil to fulfill its environmental and climate obligations. Brazil, in turn, more likely, will focus on South-South cooperation without entering into confrontation with the EU, being interested in obtaining investments and advanced technologies.

Structure Elucidation of New Kavalactone Dimers From Alpinia zerumbet Pericarps Using NMR Calculations.

Alpinia zerumbet (Pers.) B.L.Burtt & R.M.Sm, known as shell ginger, is an aromatic plant widely distributed in tropical and subtropical regions. In Guizhou Province of China, its mature fruits have been used by the Miao people for the treatment of cardiovascular diseases. Although the bioactivities of mature fruits of A. zerumbet are derived from phytochemicals in the seeds and pericarps of the plant, there remains a dearth of reports on the isolation of phytochemicals from the pericarp of A. zerumbet. In the present study, the pericarps of mature fruits of A. zerumbet were extracted, and two new kavalactone dimers, alpingsin E (1) and aniba dimer D (2), were isolated. Their structures were determined on the basis of extensive spectroscopic analysis and NMR calculations. Especially, density functional theory-based NMR chemical shift calculations were employed to elucidate and confirm the relative configuration of 1 and 2.

An amphiphilic peptide with unnatural amino acids as an alignment medium for RDC measurements

The multiple oligopeptides have been regarded as promising alignment media due to their structural diverseness and tendency for self-assembly in solution. Herein, an assembled amphiphilic peptide alignment medium, i.e., C15-CONH-Phg-Phg-IIIKK-CONH2 with unnatural amino acids for the determination of anisotropic parameters of NMR is introduced. The amphiphilic peptide can be self-assembled at low concentrations in DMSO and is stable and highly homogeneous. The NMR spectrum collected with the addition of the medium had fewer background signals. The utility of the acquired RDC data is demonstrated to determine relative configuration of three natural products, Helminthosporic acid, Estrone, and α-Santonin.

Up-Scaling Solar Hydrogen Production: Development and Demonstration of Photoelectrochemical Reactors

For commercially viable photoelectrochemical hydrogen production, considerable progress must still be made in the development and demonstration of up-scaled devices. The development of low cost and scalable photoelectrode materials that can harness light over a wide range of wavelengths, catalyse water oxidation/reduction, and are chemically, (photo)electrochemically and mechanically robust, remains a bottleneck on which research efforts are largely focused. The design and demonstration of up-scaled devices is equally important and must be addressed in parallel, to ensure material compatibility with the systems they will be used in. The constraining factors that must be considered in device design include: (i) electrode scale-up; (ii) modes of illumination; (iii) current distribution (and associated losses); (iv) the utilisation of a membrane; (v) heat and mass transport.[1] I will present the steps we have taken to address these.Our up-scaled photoelectrochemical reactor has an irradiance area of 60 cm2 and is capable of splitting water and oxygen using only photon energies. The reactor was irradiated outdoors with natural sunlight during March, April and May 2024 at Stellenbosch University, South Africa (33.93° S, 18.86° E), while mounted on a 2-axis tracking platform. Light was directed laterally both into the (photo)cathode and photoanode compartments, which were separated by an ion-permeable membrane.The reactor was operated in two modes: Photoelectrochemical (PEC), with an FTO|WO3|BiVO4|NiFeOx photoanode and a FTO|Au|Sb2Se3|CdS|TiO2|Pt photocathode[2]; PV-assisted photoelectrochemical (PV-PEC), with an FTO|WO3|BiVO4|NiFeOx photoanode, Ni cathode and externally mounted c-Si PVs. Two modes of illumination were compared:(i) Direct irradiation, through the use of mirrors;(ii) Concentrated irradiation (up to a factor of five), through the use of linear Fresnel lenses coupled with stepped Al waveguides.This research seeks to elucidate challenges of developing up-scaled materials for water splitting, to facilitate the pathway to commercially viable photoelectrochemical hydrogen production. I shall discuss the experimental results from reactor testing, the performance under various modes of irradiation, and the effects of electrode materials, geometries and relative configurations within the reactor on its design.Refs:[1] A review of inorganic photoelectrode developments and reactor scale-up challenges for solar hydrogen production, Adv. Energ. Mater., 2021, 11, 2003286.[2] Benchmark performance of low-cost Sb2Se3 photocathodes for unassisted solar overall water splitting, Nat. Commun., 2020, 11, 861. Figure 1

Diterpenoids and Triterpenoids from the Aerial Parts of Isodon serra and Their Biological Activities.

Five undescribed diterpenoids, serranins A-E (1-5), and four novel triterpenoids, serratic acids A-D (6-9), along with 32 known terpenoids (10-41) were isolated from the aerial parts of Isodon serra. The planar structures of 1-9 and their relative configurations were established on the basis of extensive spectroscopic analysis. Structurally, compounds 6-9 are the first examples of 18,19-seco-ursane p-coumaric or ferulic esters, while compounds 1-5 further enriched the plant's diterpene profile. Bioactivity evaluation revealed that four diterpenoids (2, 10, 12, and 13) exhibited potent cytotoxic activity against four cancer cell lines (B16-F10, A375, A549, and MDA-MB-231) with IC50 values below 10 μM. Remarkably, 7 and 38 exhibited a comparable antimelanogenesis effect to that of positive control (kojic acid) in B16-F10 cells.

Stereodivergent Macrocyclization in Dynamic Chiral Confinement.

The absolute and relative configurations of a macrocyclic natural product bearing multiple chirality have a crucial influence on its physical and biological properties. Nevertheless, their preparation with full stereocontrol remains largely unexplored in synthetic community. Here, we show a stereodivergent macrocyclization under dynamic chiral confinement in which the stepwise chirality switching of a chiral space directs complete stereocontrol. To confine a substrate in a dynamic chiral space, we used a chiral capsule enclosing a substrate which is collectively switchable in the chirality in response to external stimuli, but their conformations are firmly fixed by subsequent self-assembly. The consecutive chirality switching enables the confined reactions of an enclosed achiral substrate to sequentially install diverse chirality on a macrocycle product with full stereocontrol in a single pot operation, thus changing only a sequence of physical stimuli enables access to a remarkable stereodivergence in a macrocyclization process.

Analyzing heat transfer performance of ARCH lattice microchannel heat exchanger fabricated using selective laser melting

Lattice structures are emerging as highly effective heat exchange mediums in exchangers and radiators due to their low weight, high specific stiffness and strength, and extensive surface area. These attributes render them particularly suitable for enhancing heat transfer efficiency while maintaining a lightweight and structurally sound design. Certain applications, such as hot stamping, demand both high heat transfer performance and significant load-bearing capacity. Arch micro-strut (ARCH) lattice is a kind of high load-bearing lattice. Currently, there is a gap in the research on its heat transfer performance. This study provides a comprehensive analysis of the heat transfer and mechanical performance of additively manufactured ARCH lattice structures. Deionized water (DI water) was selected as the working fluid in this study. The analysis spans various relative densities, inlet velocities, array orientations, and gradient configurations, employing both experimental and simulation approaches. The results of this study reveal that as relative density increases, the pressure drop gradually rises, while the convective heat transfer coefficient increases before stabilizing. The pressure drop reaches a maximum of 348 kPa at 4 m/s, 40 % relative density, and the convective heat transfer coefficient reaches a maximum of 13,805 W/m2·k at 4 m/s, 20 % relative density. At a relative density of 20 %, the convective heat transfer coefficient reaches its maximum at the same inlet velocity. Specifically, at an inlet velocity of 4 m/s, the convective heat transfer coefficient for a 20 % relative density is 115 % higher than that at 0 %. The maximum Von Mises stress and deformation decrease progressively as relative density increases, from 980.72 MPa to 236.05 MPa, suggesting a substantial enhancement in the compressive properties of the structure. Additionally, a higher inlet velocity results in an enhanced convective heat transfer coefficient. The convective heat transfer coefficient increased by an average of 2300 W/m2·k when the flow rate increased from 1 m/s to 4 m/s. The anisotropic nature of ARCH lattice structure significantly affects mechanical properties and heat transfer efficiency, with the heat transfer coefficient being higher at the inlet along X-direction compared to Z-direction, and a lower pressure drop in X-direction. The gradient structure is shown to effectively address the non-uniform heat dissipation requirements of various components. Specifically, decreasing gradient (DG) configuration offers superior heat transfer performance under similar pressure drop conditions, while increasing gradient (IG) configuration provides better temperature uniformity. Overall, ARCH lattice structure demonstrates superior performance compared to face-centered cubic with vertical strut (FCCZ) structure, with an efficiency index approximately 200 % higher than that of FCCZ structure.

Generation of 10 kT axial magnetic fields using multiple conventional laser beams: A sensitivity study for kJ PW-class laser facilities

Strong multi-kilotesla magnetic fields have various applications in high-energy density science and laboratory astrophysics, but they are not readily available. In our previous work [Y. Shi et al., Phys. Rev. Lett. 130, 155101 (2023)], we developed a novel approach for generating such fields using multiple conventional laser beams with a twist in the pointing direction. This method is particularly well-suited for multi-kilojoule petawatt-class laser systems like SG-II UP, which are designed with multiple linearly polarized beamlets. Utilizing three-dimensional kinetic particle-in-cell simulations, we examine critical factors for a proof-of-principle experiment, such as laser polarization, relative pulse delay, phase offset, pointing stability, and target configuration, and their impact on magnetic field generation. Our general conclusion is that the approach is very robust and can be realized under a wide range of laser parameters and plasma conditions. We also provide an in-depth analysis of the axial magnetic field configuration, azimuthal electron current, and electron and ion orbital angular momentum densities. Supported by a simple model, our analysis shows that the axial magnetic field decays owing to the expansion of hot electrons.

Stereocontrolled Synthesis of 1,4-Dicarbonyls via [3,3]-Sulfonium Rearrangement and Application to the Synthesis of Heterocycles

AbstractDue to an inherent polarity mismatch of the corresponding retrosynthetic synthons, 1,4-dicarbonyl synthesis through polar pathways requires a retrosynthetic rethink. While umpolung-based approaches exist, efficient control of both the absolute and relative configuration of newly formed stereogenic centres within this motif has long proven particularly challenging. In this Synpact article, we highlight our work on the stereodivergent synthesis of 1,4-dicarbonyl compounds through an unusual transformation that relies on vinyl sulfoxides and ynamides as reactants. This method allows stereoselective access to each and every one out of the four possible stereoisomers of a generic 1,4-dicarbonyl target in a process where enantio- and diastereoselectivity are ‘dialled into’ the vinyl sulfoxide partner. Recent studies show that the thus formed 1,4-dicarbonyls serve as excellent linchpins for structural diversification into highly substituted heterocycles, including those found in natural products.1 Introduction2 [3,3]-Sigmatropic Rearrangement of Ynamides and Vinyl Sulfoxides under Acid Catalysis3 Cyclisation towards γ-Lactones and γ-Lactams4 Application in Total Synthesis5 Conclusion

The biologically and ecologically important natural products from the Chinese sea hare Bursatella leachii: structures, stereochemistry and beyond

A novel amide alkaloid, bursatamide A (1), featuring an unprecedented propyl-hexahydronaphthalene carbon framework, was isolated from the infrequently studied sea hare Bursatella leachi, alongside a new 3-phenoxypropanenitrile alkaloid, bursatellin B (2), and twelve known compounds. The structures of 1 and 2 were elucidated through comprehensive spectroscopic data analyses, while their relative and absolute configurations (ACs) were established through total synthesis and a series of quantum chemical calculations, including calculated electronic circular dichroism (ECD) spectra, optical rotatory dispersion (ORD) methods, and DP4+ probability analyses. Bursatamide A (1) demonstrated inhibitory effects against the human pathogenic bacteria Listeria monocytogenes and Vibrio cholerae. Erythro-bursatellin B (21), a diastereoisomer of 2, exhibited notable antibacterial activity against the fish pathogenic bacterium Streptococcus parauberis FP KSP28, with an MIC90 value of 0.0472 μg·mL−1.

Structure elucidation, biosynthetic gene cluster distribution, and biological activities of ketomemicin analogs in Salinispora.

We report three new ketomemicin pseudopeptides (1-3) from extracts of the marine actinomycete Salinispora pacifica strain CNY-498. Their constitution and relative configuration were elucidated using NMR, mass spectrometry, and quantum chemical calculations. Using GNPS molecular networking and publicly available Salinispora LCMS datasets, five additional ketomemicin analogs (4-8) were identified with ketomemicin production detected broadly across Salinispora species. The ketomemicin biosynthetic gene cluster (ktm) is highly conserved in Salinispora, occurring in 79 of 118 public genome sequences including eight of the nine named species. Outside Salinispora, ktm homologs were detected in various genera of the phylum Actinomycetota that might encode novel ketomemicin analogs. Ketomemicins 1-3 were tested against a panel of eleven proteases, with 2 displaying moderate inhibitory activity. This study describes the first report of ketomemicin production by Salinispora cultures, the distribution of the corresponding biosynthetic gene cluster, and the protease inhibitory activity of new ketomemicin derivatives.

Subsurface basement structures of the Usangu basin, East African rift system, with implications for basin structural configuration and hydrocarbon potential

The Usangu basin is a rift basin developed along the Eastern arm of the East African rift system trending in the NE-SW direction. Although the general structures of the basin have been well studied, the structural configuration of the basin and the spatial and depth variations of sediment thickness are still not well known. This study investigates the structures related basement configuration and the variation of sediment thickness within the basin using the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM), aeromagnetic and gravity data. Results from DEM data indicate a few lineaments on the basin flanks representing the Usangu and Chimala border faults with no structures in the central part of the basin. The aeromagnetic and gravity data highlight three sets of normal and strike-slip faults, most of which trend NE-SW and others NNE-SSW, while a few trends WNW-ESE or NW-SE. Structures on the southwest of the basin reveal complex patterns attributed to the concentration of important tectonic and seismic activities in the study area. The Euler deconvolution and gravity models used to calculate the depth to the basement show that the basement is shallow in the north and south to southwest, and the basin deepens in the northeastern, northwestern and western parts. The findings also reveal that the basin has two grabens, troughs, depression and intrabasinal basement trending in the same direction as the basin configuration. The general thickness of sediments filling the basin ranges from 3 to 4.5 km, with the maximum accumulation of sediments reaching up to 4.8 km in the two depocenters at the south and southwest of the basin. The depth range of the sediments obtained implies that the basin has potential for hydrocarbon exploration with the possibility of natural gas occurrence.

Field pullout test and anchorage length calculation for external anchorage of GFRP anti-floating anchors

Field pullout destructive tests of GFRP anti-floating anchors with different anchorage lengths and different anchorage forms are carried out on inverted foundation slabs. Explore the damage patterns and anchorage mechanisms of bent anchors, straight anchors and GFRP anchors with different bending configurations in relation to the concrete foundation slab. Calculate the reasonable anchorage length of anti-floating anchors. The test results show that the straight line anchor rod and bent anchor rod are mainly damaged by sliding. The displacement of anchor rod body decreases with the increase of anchorage length, bending radius and bending length. The bending treatment of anchor rods reduces the pullout bearing capacity of GFRP anti-floating anchors, but it can significantly reduce the rod displacement. The longer the length of the bent section of the anchor rod body and the larger the bending radius, the lower the strength utilization of the anchor rod body. Through the calculation of the test results of different anchorage length anti-floating anchor rods, it is found that the current calculation method for the basic anchorage length of anchor rods is too conservative. For the actual anti-floating project, a more reasonable anchorage length calculation method is proposed, and the reasonable anchorage length of anchor rods for this test condition is 370–530 mm.