Search Results (37)

The safety concerns associated with sensitivity issues regarding long nitrogen chain-based energetic compounds, especially for eight or more catenated nitrogen atoms in backbones, need to be resolved. Incorporating specific functional groups represents a key approach for enhancing stability in organic energetic materials. This study reports the synthesis of 1,1′-(diazene-1,2-diyl)bis(4-nitro-1H-1,2,3-triazole-5-carboxamide) (S8), an N8-chain compound featuring strategically placed amide groups. Employing THA(O-tosylhydroxylamine) and KMnO₄, 1,1′-(diazene-1,2-diyl)bis(4-nitro-1H-1,2,3-triazole-5-carboxamide) (S8) was synthesized and underwent N-amination and oxidative azo coupling. Comprehensive characterization, including X-ray diffraction, mechanical sensitivity testing, and theoretical analysis, alongside comparative studies with known N8 compounds, revealed that S8 exhibits unprecedented stability within its class. Among reported N8-catenated nitrogen chain compounds, attributed to the incorporation of the amide functionality, S8 demonstrates the highest impact sensitivity (IS = 10 J) and friction sensitivity (FS = 40 N) while maintaining excellent detonation performance (D = 8317 ms⁻¹, P = 28.27 GPa). This work highlights the amide group as a critical structural part for achieving high stability in sensitive long-nitrogen-chain energetic materials without compromising performance. Full article

Previous research on non-finite catenative complementation (for example, start Ving/to V; force NP into Ving/to V) has largely been restricted to BrE and/or AmE. The present study seeks to expand the regional coverage of such research by analysing a set of catenative constructions in two large web-derived corpora, GloWbE and NOW, both of which comprise 20 subcorpora representing different national varieties of English. The implications of the findings for such diachronically relevant phenomena as colloquialisation and grammaticalisation are considered. For example, the dominance of bare infinitivals over to infinitivals with catenative help is suggestive of auxiliarisation, an interpretation supported by the semantically bleached sense of generalised causation associated with help, and historical evidence of support for the bare-infinitival variant in colloquial registers. Notable findings include American English epicentrality—and possibly hypercentrality—in many of the results, with Canadian English and Philippine English in particular sharing the American aversion to from-less “prevent NP Ving” and “help to V”; the occasional conservative tendency of the Outer Circle varieties to resist diachronic trends associated with the reference varieties (such as the rise of “fear Ving” at the expense of “fear to V”); and high scores for the African Englishes, suggested to be attributable to the popularity of “serial verb” constructions in a number of African languages. Full article

The design, construction, and operation of devices and machines at the molecular scale using the bottom-up approach captivates a lot of interest in nanoscience. Particularly intriguing are interlocked molecular architectures, which are ideal candidates for these aims. [n]Pseudorotaxanes, [n]rotaxanes, and [n]catenanes serve as versatile prototypes for constructing molecular machines because they can be engineered to execute a diverse range of functions, including mechanical-like movements in response to chemical, photochemical, or electrochemical stimuli. The study explores the synthesis and characterization of a two-station two-gate calix[6]arene-based [2]catenane. Building on prior work with calix[6]arene-based Mechanically Interlocked Molecules (MIMs), this research integrates two functional gates—an azobenzene unit and a stilbene unit —into a two-station “track” ring. The synthesis employed threading and capping strategies to prepare the precursor [2]rotaxane isomers 12(azo-up) and 12(azo-down). Challenges in the deprotection of TBS groups led to the adoption of a supramolecular-assisted approach for the direct synthesis of the desired pseudorotaxane. The final catenation reaction, using a trans-stilbene-based bisacyl chloride as the “clipping unit”, afforded the [2]catenane C3(azo-down) in 25% yield after purification. Mass spectrometry and NMR spectroscopy confirmed the successful synthesis and orientation of C3(azo-down). Full article

The reactions of the angular ligand 4,4′-oxybis(N-(pyridin-3-yl)benzamide) (L¹) and 1,4-naphthalenedicarboxylic acid (1,4-H₂NDC) with divalent metal salts yielded three distinct coordination polymers (CPs): {[Zn₂(L¹)(1,4-NDC)₂]·MeOH}_n, 1, {[Cu(L¹)(1,4-NDC)(H₂O)]·3H₂O}_n, 2, and {[Cd(L¹)(1,4-NDC)]·2H₂O}_n, 3. Complex 1 features a 2-fold interpenetrated 3D framework with the (4¹²·6³)-pcu topology, while complex 2 reveals a 1D triple-strained helical chain and complex 3 displays a 3-fold interpenetrated 3D framework with (6⁶)-dia topology. Additionally, the reactions of the flexible ligand N,N′-bis(3-methylpyridyl) adipoamide (L²) afforded {[Co₄(L²)_0.5(1,4-NDC)₃(H₂O)₃(µ₃-OH)₂]·EtOH·2H₂O}_n, 4, {[Zn₂(L²)(1,4-NDC)₂]·2CH₃OH}_n, 5, and [Cd(L²)(adipic)(H₂O)]_n (H₂adipic = adipic acid), 6, exhibiting a self-catenated 3D framework with the (4²⁰·6⁸)-8T32 topology, a 2D layer with the (4¹³·6²) − (4,4)IIb topology, and a 2D layer with the (4⁴·6²)-sql topology, respectively. The structural diversity observed in complexes 1–6 highlights the pivotal influence of the metal center on the degree of entanglement in CPs within mixed-ligand systems. The thermal stability and luminescent properties of complexes 1–3, 4, and 6 are also discussed. Full article

Before calcification begins, the early embryonic and fetal skeletal development of both mammalian Homo sapiens and the chondrichthyan fish Raja asterias consists exclusively of cartilage. This cartilage is formed and shaped through processes involving tissue segmentation and the frequency, distribution, and orientation of chondrocyte mitoses. In the subsequent developmental phase, mineral deposition in the cartilage matrix conditions the development further. The stiffness and structural layout of the mineralized cartilage have a significant impact on the shape of the anlagen (early formative structure of a tissue, a scaffold on which the new bone is formed) and the mechanical properties of the skeletal segments. The fundamental difference between the two studied species lies in how calcified cartilage serves as a scaffold for osteoblasts to deposit bone matrix, which is then remodeled. In contrast, chondrichthyans retain the calcified cartilage as the definitive skeletal structure. This study documents the distinct mineral deposition pattern in the cartilage of the chondrichthyan R. asterias, in which calcification progresses with the formation of focal calcification nuclei or “tesserae”. These are arranged on the flat surface of the endo-skeleton (crustal pattern) or aligned in columns (catenated pattern) in the radials of the appendicular skeleton. This anatomical structure is well adapted to meet the mechanical requirements of locomotion in the water column. Conversely, in terrestrial mammals, endochondral ossification (associated with the remodeling of the calcified matrix) provides limb bones with the necessary stiffness to withstand the strong bending and twisting stresses of terrestrial locomotion. In this study, radiographs of marine mammals (reproduced from previously published studies) document how the endochondral ossification in dolphin flippers adapts to the mechanical demands of aquatic locomotion. This adaptation includes the reduction in the length of the stylopodium and zeugopodium and an increase in the number of elements in the autopodium’s central rays. Full article

We evaluated the effects of fungicides on strawberry powdery mildew (PM) fungus, Podosphaera aphanis, using an electrostatic technique. Thirty-six fungicides were sprayed on single colonies of P. aphanis on leaves of strawberry seedlings (Fragaria × ananassa Duchesne ex Rozier). Colony development varied depending on the tested fungicides. Particularly, pyraziflumid, triflumizole, triforine, polyoxin, sodium hydrogen carbonate + copper wettable powder, and flutianil + mepanipyrim were highly effective for reducing colony development. P. aphanis colonies were histochemically stained to observe the morphological characteristics of fungal cells forming normal and abnormal conidiophores. Abnormal conidiophores were classified into seven types based on their morphological and cytological characteristics. Finally, asexual conidia were collected from single P. aphanis colonies on the leaves spray-treated with fungicides using a dielectrically polarized insulator plate (electrostatic spore collector); conidia attracted to the insulator plates were counted using a high-fidelity digital microscope. Most tested fungicides highly inhibited the production and/or germination of asexual conidia. The germination of asexual conidia was observed only in thiophanate-methyl (methyl benzimidazole carbamates fungicides; MBC fungicides) and azoxystrobin (quinone outside inhibitors; QoI fungicides). Assessing with the electrostatic technique, we clarified that P. aphanis has developed resistance to both thiophanate-methyl and azoxystrobin. Thus, the methodological assessment analyzing the colony development and the number of conidia released from single colonies will be helpful information for screening effective fungicides. Full article

Due to the inherent characteristics of synthetic aperture radar (SAR) imaging, SAR ship features are not obvious and the category distribution is unbalanced, which makes the task of ship recognition in SAR images quite challenging. To address the above problems, a two-level feature-fusion ship recognition strategy combining the histogram of oriented gradients (HOG) features with the dual-polarized data in the SAR images is proposed. The proposed strategy comprehensively utilizes the features extracted by the HOG operator and the shallow and deep features extracted by the Siamese network in the dual-polarized SAR ship images, which can increase the amount of information for the model learning. First, the Siamese network is used to extract the shallow and deep features from the dual-polarized SAR images, and then the HOG feature of the dual-polarized SAR images is also extracted. Furthermore, the bilinear transformation layer is used for fusing the HOG features from dual-polarized SAR images, and the grouping bilinear pooling process is used for fusing the dual-polarized shallow feature and deep feature extracted by the Siamese network, respectively. Finally, the catenation operation is used for fusing the dual-polarized HOG features and dual-polarized shallow feature and deep feature, respectively, which are used for the recognition of the SAR ship targets. Experimental results tested on the OpenSARShip2.0 dataset demonstrate the correctness and effectiveness of the proposed strategy, which can effectively improve the recognition performance of the ship targets by fusing the different level features of the dual-polarized SAR images. Full article

Multimodal sentiment analysis aims to understand people’s attitudes and opinions from different data forms. Traditional modality fusion methods for multimodal sentiment analysis con-catenate or multiply various modalities without fully utilizing context information and the correlation between modalities. To solve this problem, this article provides a new model based on a multimodal sentiment analysis framework based on a recurrent neural network with a complex attention mechanism. First, after the raw data is preprocessed, the numerical feature representation is obtained using feature extraction. Next, the numerical features are input into the recurrent neural network, and the output results are multimodally fused using a complex attention mechanism layer. The objective of the complex attention mechanism is to leverage enhanced non-linearity to more effectively capture the inter-modal correlations, thereby improving the performance of multimodal sentiment analysis. Finally, the processed results are fed into the classification layer and the sentiment output is obtained using the classification layer. This process can effectively capture the semantic information and contextual relationship of the input sequence and fuse different pieces of modal information. Our model was tested on the CMU-MOSEI datasets, achieving an accuracy of 82.04%. Full article

In this study, we evaluated the effectiveness of hyperparasitic fungi in controlling powdery mildew (PM). In a greenhouse, we spray-inoculated single colonies of the melon PM-causing fungus Podosphaera xanthii strain KMP-6N at three different fungal developmental stages (i.e., 5, 10, and 15 days old) with spores of the hyperparasitic fungus Ampelomyces sp. strain Xs-q. After spray inoculation, we collected and counted KMP-6N conidia produced as asexual progeny from PM colonies using an electrostatic rotational spore collector. Collector insulator films were replaced at 24 h intervals until KMP-6N ceased to release additional progeny conidia. Conidial releases from each of the single Xs-q-inoculated KMP-6N colonies gradually reduced, then stopped within ca. 4 and 8 days of the first treatment in 5- and 10-day-old KMP-6N colonies, and within ca. 20 days of the second spray treatment in 15-day-old KMP-6N colonies, respectively. The total numbers of asexual progeny conidia collected from single 5-, 10-, and 15-day-old colonies were ca. 156, 1167, and 44,866, respectively. After electrostatic spore collection, conidiophores in Xs-q-uninoculated KMP-6N colonies appeared normal, whereas almost all conidiophores in 5- and 10-day-old Xs-q-inoculated KMP-6N colonies were completely deformed or collapsed due to the infection of the hyperparasitic fungus. This is the first study to apply electrostatic and digital microscopic techniques to clarify the impact of fungal hyperparasitism on mycohost survival, and, in particular, to assess quantitatively and visually the suppression of conidial release from any PM colonies infected with Ampelomyces. Full article

In the literature, mainly particle-size distribution (PSD) analyses in the soil catenas, of e.g., moraine and riverine landscapes were discussed. Analysis and comparison of PSD in moraine (ML) and ice-dammed lakes (ID-LL) landscapes were not studied. Since the landscape of ice-dammed lakes origin has diversified relief and is under intensive agricultural use, the aspects of erosion are of great importance. The changes in PSD were studied in 14 soil catenas (toposequences) of eroding soils at the upper slope (US) as well as colluvial soils at the middle (MS) and lower (LS) slopes and in the depressions (D). The PSD of the fine fractions (<2 mm) was analysed according to the hydrometer method. In order to describe the effect of agricultural use on the variability of PSD in soil surface horizons, sedimentological and granulometric indices were calculated. In the studied moraine landscape, the content of coarse silt fraction was increasing in the catenal sequence from 9.7% in the US to 17.7% in the D. Similar relationships were revealed for the fine silt content. Significant differences were found between the average contents of coarse and fine silt fractions at the US as well as the LS and the D. However, such a relation was not found in the soil catena in the ice-dammed lake landscape. Eroded and colluvial soil materials were very poorly sorted with a standard deviation index of 2.65–3.69. Humus horizons of analysed soils had very fine, fine skewed PSD, mesokurtic and platykurtic distribution (ML), symmetrical, fine skewed and platykurtic distribution (I-DLL). The cluster analysis enabled the separation of two groups of soils: one group in the moraine landscape and the other in the ice-dammed lakes landscape. The PSD in studied soils was similar only among the soils within one type of landscape. Full article

The direct formation of (hetero)biaryls from readily available (hetero)aryl halides under mild reaction conditions can be efficiently achieved through the Masuda borylation–Suzuki coupling (MBSC) sequence. The MBSC sequence catenates Pd-catalyzed Masuda borylation and Suzuki coupling into a one-pot process, giving access to diverse symmetrically and unsymmetrically substituted scaffolds. (Hetero)biaryls are ubiquitous structural motifs that appear in natural products, pharmaceutically relevant scaffolds, functional dyes, and several other structures. This review summarizes the development of the MBSC sequence and its improvements over the past two decades. Full article

Abnormal sulfide catabolism, especially the accumulation of hydrogen sulfide (H₂S) during hypoxic or inflammatory stresses, is a major cause of redox imbalance-associated cardiac dysfunction. Polyhydroxynaphtoquinone echinochrome A (Ech-A), a natural pigment of marine origin found in the shells and needles of many species of sea urchins, is a potent antioxidant and inhibits acute myocardial ferroptosis after ischemia/reperfusion, but the chronic effect of Ech-A on heart failure is unknown. Reactive sulfur species (RSS), which include catenated sulfur atoms, have been revealed as true biomolecules with high redox reactivity required for intracellular energy metabolism and signal transduction. Here, we report that continuous intraperitoneal administration of Ech-A (2.0 mg/kg/day) prevents RSS catabolism-associated chronic heart failure after myocardial infarction (MI) in mice. Ech-A prevented left ventricular (LV) systolic dysfunction and structural remodeling after MI. Fluorescence imaging revealed that intracellular RSS level was reduced after MI, while H₂S/HS⁻ level was increased in LV myocardium, which was attenuated by Ech-A. This result indicates that Ech-A suppresses RSS catabolism to H₂S/HS⁻ in LV myocardium after MI. In addition, Ech-A reduced oxidative stress formation by MI. Ech-A suppressed RSS catabolism caused by hypoxia in neonatal rat cardiomyocytes and human iPS cell-derived cardiomyocytes. Ech-A also suppressed RSS catabolism caused by lipopolysaccharide stimulation in macrophages. Thus, Ech-A has the potential to improve chronic heart failure after MI, in part by preventing sulfide catabolism. Full article

Recently, hyperspectral image (HSI) classification has become a hot topic in the geographical images research area. Sufficient samples are required for image classes to properly train classification models. However, a class imbalance problem has emerged in hyperspectral image (HSI) datasets as some classes do not have enough samples for training, and some classes have many samples. Therefore, the performance of classifiers is likely to be biased toward the classes with the largest samples, and this can lead to a decrease in the classification accuracy. Therefore, a new deep-learning-based model is proposed for hyperspectral images generation and classification of imbalanced data. Firstly, the spectral features are extracted by a 1D convolutional neural network, whereas a 2D convolutional neural network extracts the spatial features and the extracted spatial features and spectral features are catenated into a stacked spatial–spectral feature vector. Secondly, an autoencoder model was developed to generate synthetic images for minority classes, and the image samples were balanced. The GAN model is applied to determine the synthetic images from the real ones and then enhancing the classification performance. Finally, the balanced datasets are fed to a 2D CNN model for performing classification and validating the efficiency of the proposed model. Our model and the state-of-the-art classifiers are evaluated by four open-access HSI datasets. The results showed that the proposed approach can generate better quality samples for rebalancing datasets, which in turn noticeably enhances the classification performance compared to the existing classification models. Full article

Powdery mildew fungi produce progeny conidia on conidiophores, and promote the spread of powdery mildew diseases by dispersal of the conidia from conidiophores in the natural environment. To gain insights and devise strategies for preventing the spread of powdery mildew infection, it is important to clarify the ecological mechanism of conidial dispersal from conidiophores. In this study, all of the progeny conidia released from single colonies of strawberry powdery mildew fungus (Podosphaera aphanis (Wallroth) U. Braun and S. Takamatsu var. aphanis KSP-7N) on true leaves of living strawberry plants (Fragaria × ananassa Duchesne ex Rozier cv. Sagahonoka) were consecutively collected over the lifetime of the colony with an electrostatic rotational spore collector (insulator drum) under greenhouse conditions, and counted under a high-fidelity digital microscope. The insulator drum consisted of a round plastic container, copper film, thin and transparent collector film, electrostatic voltage generator, and timer mechanism. When negative charge was supplied from the voltage generator to the copper film, the collector film created an attractive force to trap conidia. The electrostatically activated collector film successfully attracted progeny conidia released from the colony. Experiment was carried out at just one colony on one leaf for each month (in February, May, July, October, November, and December in 2021), respectively. Each collector film was exchanged for a new collector film at 24 h intervals until KSP-7N ceased to release progeny conidia from single colonies. Collection experiments were carried out to estimate the total number of conidia released from a single KSP-7N colony over a 35–45-day period after inoculation. During the fungal lifetime, KSP-7N released an average of 6.7 × 10⁴ conidia from each of the single colonies at approximately 816 h. In addition, conidial release from KSP-7N colonies was largely affected by the light intensity and day length throughout a year; the number of conidia released from single KSP-7N colonies in night-time was clearly smaller than that in daytime, and the time of conidial release from single KSP-7N colonies was shorter by approximately 2 to 4 h in autumn and winter than in spring and summer. The ecological characteristics related to conidial releases from KSP-7N colonies will be helpful information for us to successfully suppress the spread of strawberry powdery mildews onto host plants under greenhouse conditions. Full article

Bioinspired porous microstructures of iron-tannate (Fe(III)-TA) coordination polymer framework were synthesized by catenating natural tannic acid with iron(II), using a scalable aqueous synthesis method in ambient conditions. The chemical composition, morphology, physiochemical properties, and colloidal stability of microstructures were elucidated. The surface area (S_BET) and the desorption pore volume were measured to be 70.47 m²/g and 0. 44 cm³/g, respectively, and the porous structure was confirmed with an average pore dimension of ~27 nm. Microstructures were thermally stable up to 180 °C, with an initial weight loss of 13.7% at 180 °C. They exhibited high chemical stability with pH-responsive amphoteric properties in aqueous media at pH levels ranging from 2 to 12. Supporting their amphoteric sorption, microstructures exhibited rapid removal of Pb⁺² from water, with 99% removal efficiency, yielding a maximum sorption capacity of 166.66 mg/g. Amphoteric microstructures of bioinspired metal–phenolate coordination polymers remain largely unexplored. Additionally, natural polyphenols have seldomly been used as polytopic linkers to construct both porous and pH-responsive amphoteric coordination polymer frameworks with a robust structure in both acidic and basic media. Thus, this de novo porous microstructure of Fe(III)-TA and its physiochemical surface properties have opened new avenues to design thermally and chemically stable, eco-friendly, low-cost amphoteric sorbents with multifunctionality for adsorption, ion exchange, separation, storage, and sensing of both anions and cations present in heterogeneous media. Full article