Planar Structure Research Articles

Linderangolides A−D, four new butanolides from the roots of Lindera angustifolia and their cytotoxic activity

Four undescribed butanolides, linderangolides A–D (1–4), along with four known congeners, lincomolide A (5), (−)-epilitsenolide C2 (6), (−)-epilitsenolide C1 (7) and litseakolide H (8), were isolated from the roots of Lindera angustifolia. The planar structures of 1–4 were elucidated based on extensive spectroscopic analyses, the relative and absolute configurations of 1–4 were determined by the NOESY spectra and the comparison of calculated and experimental ECD. The cytotoxic activities of all isolated compounds were tested, 4 showed inhibitory activity against SGC-7 cells with IC50 value of 6.62 μM.

Aggregation of Homogeneous Porphyrin Catalysts in Organic Electrolyte Broadly Inhibits Electrochemical CO2 Reduction Performance

Metalloporphyrins are widely used as homogeneous electrocatalysts for the production of renewable fuels from abundant feedstocks and sustainable energy. The modularity of porphyrin catalysts has led to the establishment of structure‐function correlations that aid in predicting and optimizing catalytic activity. Although metalloporphyrins are widely known to aggregate due to their planar structure that promotes π–π stacking, it is surprising that the influence of metalloporphyrin aggregation on electrocatalytic performance has not been previously investigated. Herein, we will document the relative aggregation and electrocatalytic activity for CO2 reduction to CO with three structurally related iron meso-phenylporphyrins in commonly used N,N-dimethylformamide (DMF) electrolyte. An inverse dependence of kinetics on catalyst concentration is observed for all three porphyrins based on cyclic voltammetry data. Furthermore, this inhibition extends to bulk electrolysis performance, where up to 75% of the catalyst in a 1 mM solution is inactive compared to in a 0.25 mM solution. This talk will additionally discuss how aggregation is influenced by organic additives, axial ligands, redox state, metal identity, and porphyrin substituents. Overall, this work emphasizes that metalloporphyrins can aggregate severely (even in well-solubilizing organic electrolytes) and that aggregation effects must be considered for optimization of performance and for meaningful catalytic activity comparisons.

Machine learning validated compact circularly polarized dual port-MIMO antenna with polarization diversity for ku-band applications

A novel dual Port C-Shape MIMO broadband printed antenna with wide axial ratio bandwidth (ARBW) is modelled and built for Ku band Applications. The unit cell of the proposed antenna has a compact size of 25 × 26 × 0.8 mm3 engraved on RT duriod 5880 material (ε r = 2.2, thickness of 0.8 mm). The proposed model consists of C shaped radiator, plus symbol structure and a modified ground plane. The machine learning concept is used to investigate the dimensional dependency of the plus sign on the CP behaviour. The suggested antenna shows impedance bandwidth (−10 dB) and 3-dB ARBW of 6 GHz (12 GHz to 18 GHz) which is covering the whole Ku band. The diversity performance parameters and antenna parametric investigation is also carried out to justify the MIMO identity of the proposed design. The simulated and measured counterparts are found in harmony. The strength of the proposed antenna is its planar structure, wide ARBW, polarization diversity, and wide operating Ku bandwidth.

Destabilization of Oxygen Reduction Reaction Intermediates on a PGM-Free Electrocatalyst By Axial Spectator Ligands

Platinum-group free Fe-N-C catalysts have been shown to be a promising class of electrocatalysts for the oxygen reduction reaction (ORR) in acidic media. However, typical synthesis methods can result in a variety of FeN4 sites embedded in graphene, including bulk-hosted and edge-hosted FeN4. The planar structure of the FeN4 active site allows two additional ligands to adsorb to Fe on either side of the graphene, which can be present from ORR reaction intermediates and other solution phase species. Here, we studied the impact of axially adsorbed ligands on bulk-hosted and edge-hosted FeN4 sites by screening over all pairs of H, O, OH, OOH, O2, H2O, NO, SO4, HSO4, and ClO4 axial ligands using solvated grand canonical density functional theory (GCDFT) to self-consistently account for applied potential. The first axial Fe adsorbate can strongly influence the binding of a second axial adsorbate and increase its adsorption energy by up to 2 eV, with more destabilization occurring for a more positive applied potential and the O* ORR intermediate being affected most. However, GCDFT calculations on these same sites without axial spectator ligands show that O* and OH* are both thermodynamically persistent, suggesting that axial spectator ligands might play a role in explaining this catalyst’s high experimental activity. Additionally, we show how the combined effects of potential, nature of the FeN4 site, and axial ligand impact O2 adsorption favorability and availability of sites in the presence of competing molecules. This work highlights the need for the continued development of advanced electrocatalyst models that account for a wide range of active site structures to facilitate comparison with experiment.

Programmable Assembly of Semiconductor Mesostructures Via Inorganic Phototropism

Plants exhibit a phototropic response and direct the addition of new biomass to optimize collection of solar insolation. Analogous inorganic phototropism growth enables the programmable assembly of complex 3D nanoarchitectures with instruction by an incoherent, unstructured, mW cm-2 intensity light beam. Inorganic phototropism has been demonstrated via the light-mediated electrochemical assembly of semiconductor deposits from solution-phase precursor ions. No structured light field (no photomask), no lithographic processes and no templating agents (ligands, surfactants, etc.) are utilized. Nevertheless, ordered nanoscale features are conformally assembled over full macroscale (cm2) areas with feature heights on the order of several um with growth times < 5 min. In-plane anisotropy is a function of the input polarization. Isotropic morphologies consisting of ordered arrays of nanoscale holes were generated using unpolarized illumination whereas linearly polarized light resulted in anisotropic lamellar structures with in-plane orientations set by the polarization direction. The structure pitch was dependent on the spectral distribution of the input light with shorter wavelengths effecting higher feature densities. The out-of-plane growth direction is related to the propagation direction of the input light. Time-varying optical inputs enable programming of 3D intricacy by evolving the in-plane structure along the out-of-plane dimension, e.g. an abrupt reduction in the input wavelength results in a concomitant increase in the interfacial density resulting in tuning fork structures. Additional morphological control has also been effected by using multiple simultaneous illumination inputs. Modeling of the growth using a combination of full-wave electromagnetic simulations of light absorption and scattering coupled with Monte Carlo simulations of mass addition successfully reproduced the experimentally observed morphologies and indicated that assembly was directed by evolution of the growth front to maximize anisotropic light collection. The assembly was observed to be a highly emergent phenomenon involving optical communication between neighboring features including cooperative scattering and synergistic absorption.

Synthesis, magnetic and dye adsorption properties of three metal-organic frameworks based on purine carboxylic acid

Three metal-organic frameworks (MOFs), namely [La(L)Cl(H2O)2]n (1), {[Nd(L)Cl(H2O)3]•2H2O}n (2) and {[Pr2(L)2Cl2(H2O)6]•H2O}n (3), were successfully structured based on ligand 5-((6H-purin-6-yl)amino)isophthalic acid (H2L). X-ray single-crystal diffraction analysis showed that MOFs 1–3 possessed the similar two-dimensional (2D) planar structure. Adsorption experiments showed that MOFs 1–3 exhibited good adsorption effect on Congo red (CR), and their maximum adsorption capacities were 1428, 433 and 319 mg·g−1, respectively. The adsorption kinetics and isotherms showed that the adsorption process conformed to the quasi-second-order kinetic model and the Langmuir model, respectively. The adsorption process belonged to chemical adsorption and monolayer adsorption. The adsorption mechanism mainly involves hydrogen bonding, π-π stacking interaction and electrostatic interaction. In addition, the magnetic test results showed that MOFs 2 and 3 have typically antiferromagnetic behavior.

Excited-State Intramolecular Proton Transfer toward Conical Intersections in Indigo, Epindolidione, and Indirubin.

Indigo exhibits a high degree of photostability, experimentally supported by observations such as quenching of fluorescence and an exceptionally short excited-state lifetime. Epindolidione, a structural isomer of indigo, is highly fluorescent in contrast to indigo, while indirubin, another structural isomer, exhibits weak fluorescence similar to that of indigo. To elucidate the origin of the difference in photophysical and photochemical behavior, potential energy profiles of the excited-state intramolecular proton transfer in indigo, epindolidione, and indirubin are computationally studied by quantum chemical calculations using the TDDFT and extended MS-CASPT2 (XMS-CASPT2) methods. As a result, it is found that indigo and indirubin exhibit little energy barrier for the single proton transfer (SPT) in the S1(ππ*) state from the diketo to keto-enol form and low energy of the S1/S0 conical intersection (CI) in the latter form with a planar molecular structure. Epindolidione, on the other hand, exhibits much higher barriers for SPT and access to CI. These results suggest that the excited-state SPT and subsequent nonradiative deactivation via CI are more likely to occur in indigo and indirubin than in epindolidione, which is consistent with the experimental observations described above. For indigo and epindolidione, the deactivation channels via the second SPT from the keto-enol to dienol form are also compared.

Resilient and Reversible Phosphotungstic Acid Passivated Zinc Anode.

Aqueous zinc ion batteries (ZIBs) present a compelling solution for grid-scale energy storage, which is crucial for integrating renewable energy resources into the electric infrastructure. The cycling stability of ZIBs hinges on the electrochemical reversibility of the zinc anode, which is often compromised by corrosion and dendritic zinc deposition. Here, we present a straightforward surface passivation strategy that significantly enhances the cycling stability of zinc anodes. By immersing zinc in a solution of phosphotungstic acid, we promoted the dominance of the 002 plane of zinc's hexagonal structure. This process facilitates the creation of a uniform nucleation and protective layer on the native zinc surface, resulting in a more uniform plating-stripping process and increased corrosion resistance. In symmetric cells, the passivated zinc exhibits a capacity retention of 68.7% after 1000 cycles at a current density of 1.0 Ag1-, whereas untreated zinc anodes retain only 7.4% of capacity under identical conditions. In full cell zinc iodine batteries employing the passivated zinc anode, over 1000 stable charge-discharge cycles were achieved at a current density of 20 mA cm-2, with approximately 96% Coulombic efficiency (CE), 86% voltage efficiency (VE), and 82% energy efficiency (EE). This study demonstrates a promising pathway for the construction and upscaling of flow batteries with high capacity and low cost.

Plasma-enhanced atomic layer deposition of titanium nitride for superconducting devices

This study examines the superconducting properties of titanium nitride (TiN) deposited via plasma-enhanced atomic layer deposition on both planar and three-dimensional (3D) structures. Our deposition method achieves consistent uniformity, maintaining sheet resistance (R□) &amp;gt; 95% across a 6-in. wafer, crucial for large-scale superconducting device fabrication and yield optimization. The planar films, akin to reactive-sputtered TiN, reached a critical temperature (Tc) of 4.35 K at a thickness of ≈40 nm. For aspect ratios (ARs) between 2 and 40, we observed a single transition of ≈2 K at ARs between 2 and 10.5, and multiple transitions at ARs &amp;gt; 10.5. We discuss mechanisms influencing superconducting properties in the 3D structures, aligning with current and future superconducting technologies.

Printing Completely Conformal Liquid Metal Circuits on Arbitrary Curved Surfaces via Customized Conformal Mask

Due to the excellent mechanical adaptability to curved surfaces and high circuit flexibility, conformal electronics have been developed for extensive applications including aeronautics and wearable electronics. However, conventional methods for fabricating conformal circuits are often constrained by planar structures, limiting the design flexibility and applicability of electronic devices on more complex and varied surfaces. Herein, a facial approach is proposed by combining a 3D‐printed customized conformal mask with liquid metal inkjet printing, to establish the completely conformal liquid alloy circuits’ printing technique on arbitrary curved surfaces. A 2D transient mathematical model is developed to simulate the particle deposition process during inkjet printing and the form of the circuits on curved surfaces is predicted. Moreover, parameters such as line resistance and cross‐sectional morphology of liquid metal circuits on both deformable and nondeformable surfaces are characterized. Various conformal liquid metal circuits, such as contour lines, expressions, text patterns, light‐emitting diode (LED) array illumination patterns, and multichannel pressure array intelligent skin on curved surfaces, are demonstrated. Compared to traditional conformal electronics manufacturing methods, this new approach offers the advantages of simple process, flexibility, low cost (within $0.01 cm−2), and high efficiency (exceeding 1 cm2 s−1), making it suitable for mass conformal electronics production.

Research on low-velocity impact resistance of spherical honeycomb sandwich structures

The impact resistance of spherical honeycomb sandwich structures is affected by the orientation and curvature radius of the honeycomb, which are different from those of planar honeycomb sandwich structures. In this study, concentric and coaxial spherical honeycomb sandwich structures with different curvature radii are designed, and the specimens are prepared using 3D printing technology. The impact resistance of concentric and coaxial spherical honeycomb sandwich structures with different curvature radii are investigated through low-velocity impact experiments. It is shown that the impact resistance of the concentric structure decreases with the increase of curvature radius, which is better than that of the coaxial structure with the same curvature radius. This study provides a reference for the design and application of the spherical honeycomb sandwich structure.

Sterolysin from a 1950s culture of Karlodinium veneficum (aka Gymnodinium veneficum Ballantine) forms lethal sterol dependent membrane pores

In 1957 Abbott and Ballantine described a highly toxic activity from a dinoflagellate isolated from the English Channel in 1949 by Mary Park. From a culture maintained at Plymouth Laboratory since 1950, we have been able to isolate two toxic molecules (abbotoxin and 59-E-Chloro-abbotoxin), determine the planar structures by analysis of HRMS and 1D and 2D NMR spectra, and found them to be karlotoxin (KmTx) congeners. Both toxins kill larval zebrafish with symptoms identical to those described by Abbot and Ballantine for gobies (Gobius virescens). Using surface plasma resonance the sterol binding specificity of karlotoxins is shown to require desmethyl sterols. Our results with black lipid membranes indicate that karlotoxin forms large-conductance channels in the lipid membrane, which are characterized by large ionic conductance, poor ionic selectivity, and a complex gating behavior that exhibits strong voltage dependence and multiple gating patterns. In addition, we show that KmTx 2 pore formation is a highly targeted mechanism involving sterol-specificity. This is the first report of the functional properties of the membrane pores formed by karlotoxins and is consistent with the initial observations of Abbott and Ballantine from 1957.

Development of a Zn-Based Single-Atom Nanozyme for Efficient Hydrolysis of Glycosidic Bonds.

Hydrolytic enzymes are essential components in second-generation biofuel technology and food fermentation processes. Nanozymes show promise for large-scale industrial applications as replacements for natural enzymes due to their distinct advantages. However, there remains a research gap concerning glycosidase nanozymes. In this study, a Zn-based single-atom nanozyme (ZnN4-900) is developed for efficient glycosidic bond hydrolysis in an aqueous solution. The planar structure of the class-porphyrin N4 material approximatively mimicked the catalytic centers of natural enzymes, facilitating oxidase-like (OXD-like)activity and promoting glycosidic bond cleavage. Theoretical calculations show that the Zn site can act as Lewis acids, attacking the C─O bond in glycosidic bonds. Additionally, ZnN4-900 has the ability to degrade starch and produce reducing sugars that increased yeast cell biomass by 32.86% and ethanol production by 14.56%. This catalyst held promising potential for enhancing processes in ethanol brewing and starch degradation industries.

A design of compact plasmonic lens consisting of high index dielectric gratings and metal nano-film

In this paper, a hybrid ultra-thin planar subwavelength focusing structure consisting of a high refractive index dielectric grating and a nano metal film was designed. The thickness of this structure is only 200 nm. Surface plasmon polaritons (SPPs) were excited from the nano metal film, propagated along the metal-air interface, and were then converted into a radiation field by the dielectric grating, forming a focused spot in free space. By adjusting the grating position and width parameters, the shape of the focused optical field could be controlled. The simulation results showed that, under 532 nm light irradiation, the lens could produce a 270 nm (full width at half-maximum, FWHM) spot size at a focal length of 2.46λ. Moreover, under the illumination of 633 nm and 780 nm light, the designed lenses were found to produce focal spot sizes of 304 nm (0.48λ) and 364 nm (0.47λ), respectively, which were smaller than the diffraction limit. The simplicity of this plasmonic lens design, coupled with its reduced thickness and minimal absorption loss, offered significant advantages in terms of cost-effectiveness and ease of fabrication.

Exhaustive Enumeration of Spatial Prime Structures

Prime structures are link chains with 0 DoF (degrees of freedom), not including subchains with 0 or fewer DoF, which are expected to be used in systematic kinematic and dynamic analyses of link mechanisms. This paper describes the exhaustive enumeration of spatial prime structures with three–five links. There will be more types of spatial prime structures than planar prime structures due to the variety in the DoF of kinematic pairs and the existence of prime structures with idle DoF. In the enumeration, the graphs which represent the connection of links and pairs are used. The vertices of the graphs represent the links of structures, and the edges represent the kinematic pairs. To consider the pair DoF, weights are set on edges. First, the numbers of pairs are calculated using Grübler’s equation. Second, the graphs corresponding to structures are enumerated, without considering pair DoF, and the isomorphic graphs and other inappropriate graphs are eliminated. Then, the combinations of pair DoF arrangement are enumerated, and the isomorphic graphs and graphs which correspond to non-prime structures are eliminated. Finally, prime structures with idle DoF are considered. As a result, 3, 13, and 97 kinds of spatial prime structures for 3, 4, and 5 links, respectively, are obtained.

Laser-induced ultrasound in multiple thin layers-An analytical solution.

Laser-induced ultrasound is based on the thermo-elastic conversion of absorbed short light pulses to pressure pulses. In the work presented here, laser-induced ultrasound in a planar structure of interconnected layers with variations in optical, thermal, and mechanical properties is studied. Layered structures can be used for generating wideband ultrasonic pulses specific to a chosen application. An analytical time-domain solution is derived for the resulting pressure transmitted from the layered structure. The solution is derived for an arbitrary number of layers with an arbitrary optical absorption profile. Free space Green's functions with image sources are used to derive the solution. A solution employing the Beer-Lambert law is also proposed. The simplification with reflections only at the boundaries is in agreement with previous published results. The spectral properties of the generated pulse are derived, where the effects of optical absorption coefficients and layer thicknesses are shown. The analytical solution is compared to one-dimensional (1D) simulations and a three-dimensional (3D) simulation, realised as a two-dimensional (2D) axially symmetric case, using the matlab toolbox k-Wave. The 3D simulation on-axis pressure agrees well with the 1D analytical solution when the diameter of the laser beam is larger by approximately 1 order of magnitude than the thickness of the planar layered structure.

Quinomycins with an unusual N-methyl-3-methylsulfinyl-alanine residue from a Streptomyces sp.

Four new echinomycin congeners, quinomycins M-P (1-4) were isolated from the cultures of the soil-derived Streptomyces sp. CPCC205575. The planar structures were determined by comprehensive analyses of NMR and HRESIMS/MS data. The absolute configurations were elucidated by the advanced Marfey's method combined with biosynthetic gene analysis. Compounds 1-4 represent the first examples of quinomycin-type natural products with the sulfur atom at the N,S-dimethylcysteine residue oxidized as a sulfoxide group forming the unusual N-methyl-3-methylsulfinyl-alanine residue. Bioassay results revealed that the oxidation of the sulfur atom at the Cys or Cys' residues led to dramatic decrease of cytotoxicity and antimicrobial activity.

Enhancing the Goos-Hänchen and spin-Hall shifts in planar and spherical structures through complex-frequency excitations

Enhancing the Goos-Hänchen and spin-Hall shifts in planar and spherical structures through complex-frequency excitations

Plasmonic induced transparency and slow light integrated device for graphene-based metamaterial

The terahertz excitation characteristics of a graphene-based band structure are studied. This structure has different planar band structures that can excite two bright modes and then it can achieve an excellent plasmonic induced transparency effect through the two bright modes. By analyzing the boundary conditions of the electromagnetic field, the dispersion relationship of this structure can be smoothly obtained. Furthermore, the internal loss factor in the matching coupled mode theory can be calculated. Meanwhile, the tuning performance of this simple structure is analyzed through the external voltage. The Fermi level regulated by voltage is also analyzed, and its influence on the entire tuning mechanism is studied. A detailed analysis is conducted on the slow light performance of this structure, and the influence of Fermi level on the slow light performance is explored. This investigation is expected to provide potential theoretical foundations for slow light, optical storage, and other fields.

FTIR study of light-induced proton transfer and Ca2+ binding in T82D mutant of TAT rhodopsin

Proton transfer reactions play important functional roles in many proteins, such as enzymes and transporters, which is also the case in rhodopsins. In fact, functional expression of rhodopsins accompanies intramolecular proton transfer reactions in many cases. One of the exceptional cases can be seen in the protonated form of marine bacterial TAT rhodopsin, which isomerizes the retinal by light but returns to the original state within 10−5 s. Thus, light energy is converted into heat without any function. In contrast, the T82D mutant of TAT rhodopsin conducts the light-induced deprotonation of the Schiff base at high pH. In this article, we report the structural analysis of T82D by means of difference Fourier transform infrared (FTIR) spectroscopy. In the light-induced difference FTIR spectra at 77 K, we observed little hydrogen out-of-plane vibrations for T82D as well as the wild-type (WT), suggesting that the planar chromophore structure itself is not the origin of the reversion from the K intermediate in WT TAT rhodopsin. Upon relaxation of the K intermediate, T82D forms the following intermediate, such as M, whereas K of WT returns to the original state. Present FTIR analysis revealed the proton transfer from the Schiff base to D82 in T82D upon formation of the M intermediate. It is accompanied by the second proton transfer from E54 to the Schiff base, forming the N intermediate, particularly in membranes. The equilibrium between the M and N intermediates corresponds to the protonation equilibrium between E54 and the Schiff base. We also found that Ca2+ binding takes place in T82D as well as WT but with 6 times lower affinity. An altered hydrogen-bonding network would be the origin of low affinity in T82D, where deprotonation of E54 is involved in the Ca2+ binding.