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Integrating wave energy devices with breakwaters can offer an innovative and sustainable approach by combining wave power extraction with wave attenuation. The performance of this integrated system in offshore areas is influenced by the unique characteristics of the coastline. In this paper, a semi-analytical solution was developed using the matching eigenfunction method for the oscillating water column device integrated into a pile-supported breakwater in front of a partially reflective seawall. The model was validated through the energy conservation law, the Haskind relationship, and experimental data. Detailed examinations were conducted on the effects of the seawall's reflection coefficients, the distance between the system and the seawall, the wall draft, and the chamber breadth on hydrodynamic performance. Results show that the presence of the seawall significantly influences hydrodynamic coefficients (hydrodynamic efficiency, reflection coefficient, the relative transmitted amplitude, etc.), accompanied by the piston and sloshing mode resonances inside the chamber and the confined area between the system and the seawall. Due to energy dissipated by a partially reflective seawall, the magnitude of those hydrodynamic coefficients is mitigated, together with the piston and sloshing mode resonances inside the air chamber. The cancellation of the sloshing mode resonance inside the confined area is observed for the smaller seawall's reflection coefficient. The maximum and minimum hydrodynamic efficiency occur when the system is arranged at the wave nodes and antinodes of the formed standing wave field. Lower wave reflection and better wave power extraction can be achieved by properly adjusting the chamber drafts and breadths. [ABSTRACT FROM AUTHOR]

Alumina (Al2O3) ceramics are widely used in electronics, machinery, healthcare, and other fields due to their excellent hardness and high temperature stability. However, their high brittleness limits further applications, such as artificial ceramic implants and highly flexible protective gear. To address the limitations of single-phase toughening in Al2O3 ceramics, some researchers have introduced a second phase to enhance these ceramics. However, introducing a single phase still limits the range of performance improvement. Therefore, this study explores the printing of Al2O3 ceramics by adding two different phases. Additionally, a new gradient printing technique is proposed to overcome the limitations of single material homogeneity, such as uniform performance and the presence of large residual stresses. Unlike traditional vat photopolymerization printing technology, this study stands out by generating green bodies with varying second-phase particle ratios across different layers. This study investigated the effects of different contents of sepiolite fiber (SF) and 316L stainless steel (SS) on various aspects of microstructure, phase composition, physical properties, and mechanical properties of gradient-printed Al2O3. The experimental results demonstrate that compared to Al2O3 parts without added SF and 316L SS, the inclusion of these materials can significantly reduce porosity and water absorption, resulting in a denser structure. In addition, the substantial improvements, with an increase of 394.4% in flexural strength and an increase of 316.7% in toughness, of the Al2O3 components enhanced by incorporating SF and 316L SS have been obtained. [ABSTRACT FROM AUTHOR]

Vat photopolymerization is an effective and economical method for preparing ceramic specimens with complex structures. However, the improper selection of process parameters during the preparation process limits the scope of its application. In this study, the most suitable shear rate was determined based on the solid content and rheological properties of the ceramic slurry. In addition, the specific printing‐process parameters were objectively selected, and the gray correlation method was used to determine the improved weight resolution coefficient through orthogonal experiments combined with the entropy weight method to select the most suitable printing parameters. Finally, the main debinding and sintering parameters that affect the heat treatment performance were considered, and multiple characterization methods were used to detect the specimens and study the impact of parameter changes on specimen performance. The experimental results show that when the laser power is 210 mW, the slice layer thickness is.04 mm, the scanning spacing is.05 mm, and the filling mode is XY, the green bodies have the best forming quality. When the sintering temperature is 1600°C, and the holding time is 4 h, the specimens have the best mechanical properties (the flexural strength reaches 114 MPa). [ABSTRACT FROM AUTHOR]

The widespread emergence of antibiotic-resistant bacteria highlights the urgent need for new antimicrobial agents. Albomycins are a group of naturally occurring sideromycins with a thionucleoside antibiotic conjugated to a ferrichrome-type siderophore. The siderophore moiety serves as a vehicle to deliver albomycins into bacterial cells via a "Trojan horse" strategy. Albomycins function as specific inhibitors of seryl-tRNA synthetases and exhibit potent antimicrobial activities against both Gram-negative and Gram-positive bacteria, including many clinical pathogens. These distinctive features make albomycins promising drug candidates for the treatment of various bacterial infections, especially those caused by multidrug-resistant pathogens. We herein summarize findings on the discovery and structure elucidation, mechanism of action, biosynthesis and immunity, and chemical synthesis of albomcyins, with special focus on recent advances in the biosynthesis and chemical synthesis over the past decade (2012–2022). A thorough understanding of the biosynthetic pathway provides the basis for pathway engineering and combinatorial biosynthesis to create new albomycin analogues. Chemical synthesis of natural congeners and their synthetic analogues will be useful for systematic structure–activity relationship (SAR) studies, and thereby assist the design of novel albomycin-derived antimicrobial agents. [ABSTRACT FROM AUTHOR]

Voids between primary support and secondary lining of existing tunnels pose a serious threat to safety and have become a key challenge for tunnel engineering. Due to the poor bonding performance between concrete slurry backfill and lining concrete, the integrity of supporting structures cannot be guaranteed. In recent years, vault grouting with formwork has proved to be effective in solving this problem. However, few studies have focused on the selection of grouting materials and associated grouting process parameters. In this paper, a slight-expanding concrete slurry is selected as the grouting material. The early strength growth trend of the slight-expanding slurry is explored via laboratory tests. The compatibility of the slight-expanding slurry and the lining concrete is analyzed by comparing the slump, expanding diameter, water retention and compressive strength. Bonding-body specimens were fabricated using a mold developed for this work. Furthermore, we compare the compressive strength and failure mode in order to investigate the bonding properties between the sight-expanding slurry and lining concrete at different grouting intervals and pressures. A reasonable set of operational parameters is subsequently proposed. Finally, field tests undertaken in an expressway tunnel in south China are performed in order to determine the impact of grouting with formwork on tunnel lining, while the grouting effect at the vault is evaluated using a ground penetrating radar. The slight-expanding slurry exhibited a high early strength and rapid hardening. Adding slight-expanding slurry to lining concrete at a volume ratio of 1:0.2 increased the slump, diameter and compressive strength by 13.4%, 15.6%, and 25.0%, respectively. When a grouting interval is less than 6 h, the pressure of grouting with formwork should be no less than 0.2 MPa, while for a grouting interval of 8 h, the grouting pressure should be no less than 0.4 MPa. The grouting pressure of 0.4 MPa exerts a limited effect on the existing secondary lining concrete, and the stress increment produced by grouting accounts for 6–17% of the total increment. The results presented can provide a reference for future tunnel construction. [ABSTRACT FROM AUTHOR]

With the development of 3D printing, continuous fiber reinforced composite (CFRTP C) 3D printing has received widespread attention. The print head is critical to distinguish between different components of the printing material. The printing nozzle is the key of CFRTPC 3D printing nozzle. Based on the "independent extrusion" type CFRTPC 3D printing, this paper studies the length of the heating zone of the continuous fiber reinforced filament (CFRF) printing nozzle. The research results show that when the CFRF printing speed is 300 mm/min, taking CFRF/PLA as an example, the effective heating zone length of the printing nozzle is between 2.62–5.45 mm, and the printing temperature range is between 204–234°C. Comprehensive consideration, the optimal printing zone length is 3.6 mm and the optimal printing temperature is 220 °C. The research of this paper is of great significance to the rapid development of CFRTPC 3D printer. [ABSTRACT FROM AUTHOR]

This article focuses on 3D printing of continuous glass fiber reinforced composites-polylactic acid by fused deposition modeling. An innovative continuous fiber reinforced composite 3D printer and self-made continuous glass fiber reinforced filament-polylactic acid are applied to study the influences of process parameters including printing temperature, speed, layer height, and fiber volume fraction on mechanical properties of continuous glass fiber reinforced composites-polylactic acid printing samples. Tensile and three-point bending tests are carried out to explore the mechanical responses of printed samples. Experimental results show that the mechanical properties of continuous glass fiber reinforced composites-polylactic acid printing samples are better than those of polylactic acid samples. The tensile and flexural strengths of the specimens are increased by 400% and 204% when the fiber volume fractions are about 5.21% and 6.24%, respectively. The microscopic observations of the fracture surfaces of the tensile samples are also conducted to analyze the influences of layer heights on tensile strength and failure mechanism. [ABSTRACT FROM AUTHOR]

Herbicide-resistant weeds are a growing problem worldwide. Thaxtomin phytotoxins are a group of nitrated diketopiperazines produced by the potato common scab-causing pathogen Streptomyces scabies and other actinobacterial plant pathogens. They represent a unique class of microbial natural products with distinctive structural features and promising herbicidal activity. The biosynthesis of thaxtomins proceeds through multiple steps of unusual enzymatic reactions. Advances in understanding of thaxtomins biosynthetic machinery have provided the basis for precursor-directed biosynthesis, pathway refactoring, and one-pot biocombinatorial synthesis to generate thaxtomin analogues. We herein summarize recent findings on the biosynthesis of thaxtomins and highlight recent advances in the rational generation of novel thaxtomins for the development of potent herbicidal agents. [ABSTRACT FROM AUTHOR]

The genus Streptomyces is a unique subgroup of actinomycetes bacteria that are well-known as prolific producers of antibiotics and many other bioactive secondary metabolites. Various environmental and physiological signals affect the onset and level of production of each antibiotic. Here we highlight recent findings on the regulation of antibiotic biosynthesis in Streptomyces by signaling molecules, with special focus on autoregulators such as hormone-like signaling molecules and antibiotics themselves. Hormone-like signaling molecules are a group of small diffusible signaling molecules that interact with specific receptor proteins to initiate complex regulatory cascades of antibiotic biosynthesis. Antibiotics and their biosynthetic intermediates can also serve as autoregulators to fine-tune their own biosynthesis or cross-regulators of disparate biosynthetic pathways. Advances in understanding of signaling molecules-mediated regulation of antibiotic production in Streptomyces may aid the discovery of new signaling molecules and their use in eliciting silent antibiotic biosynthetic pathways in a wide range of actinomycetes. [ABSTRACT FROM AUTHOR]

Make the switch: The three‐enzyme cassette MarG/H/I is responsible for stereospecific biosynthesis of β‐methyltryptophan from L‐tryptophan (1). MarG/I convert 1 into (2S,3R)‐β‐methyltryptophan, while MarG/I combined with MarH convert 1 into (2S,3S)‐β‐methyltryptophan. MarH serves as a stereochemical switch by catalyzing the stereoinversion of the β‐stereocenter. [ABSTRACT FROM AUTHOR]

Wahlweise: Die Drei ‐ Enzyme ‐ Kassette MarG/H/I steuert die stereospezifische Biosynthese von β ‐ Methyltryptophan aus L ‐ Tryptophan (1). MarG/I wandelt 1 in (2S,3R) ‐ β ‐ Methyltryptophan um, während MarG/I in Kombination mit MarH aus 1 das (2S,3S) ‐ β ‐ Methyltryptophan erzeugt. MarH dient als stereochemischer Schalter, indem es die Inversion des β ‐ Stereozentrums katalysiert. [ABSTRACT FROM AUTHOR]

Background: Importin-α1 belongs to a subfamily of nuclear transport adaptors and participates in diverse cellular functions. Best understood for its role in protein transport, importin-α1 also contributes to other biological processes. For instance, arsenite treatment causes importin-α1 to associate with cytoplasmic stress granules (SGs) in mammalian cells. These stress-induced compartments contain translationally arrested mRNAs, small ribosomal subunits and numerous proteins involved in mRNA transport and metabolism. At present, it is not known whether members of all three importin-α subfamilies locate to SGs in response to stress. Results: Here, we demonstrate that the oxidant diethyl maleate (DEM), arsenite and heat shock, promote the formation of cytoplasmic SGs that contain nuclear transport factors. Specifically, importin-α1, α4 and α5, which belong to distinct subfamilies, and importin-β1 were targeted by all of these stressors to cytoplasmic SGs, but not to P-bodies. Importin-α family members have been implicated in transcriptional regulation, which prompted us to analyze their ability to interact with poly(A)-RNA in growing cells. Our studies show that importin-α1, but not α4, α5, importin-β1 or CAS, associated with poly(A)-RNA under nonstress conditions. Notably, this interaction was significantly reduced when cells were treated with DEM. Additional studies suggest that importin-α1 is likely connected to poly(A)-RNA through an indirect interaction, as the adaptor did not bind homopolymer RNA specifically in vitro. Significance: Our studies establish that members of three importin-α subfamilies are bona fide SG components under different stress conditions. Furthermore, importin-α1 is unique in its ability to interact with poly(A)-RNA in a stress-dependent fashion, and in vitro experiments indicate that this association is indirect. Collectively, our data emphasize that nuclear transport factors participate in a growing number of cellular activities that are modulated by stress. [ABSTRACT FROM AUTHOR]

Polyene macrolides are a large family of natural products typically produced by soil actinomycetes. Polyene macrolides are usually biosynthesized by modular and large type I polyketide synthases (PKSs), followed by several steps of sequential post-PKS modifications such as region-specific oxidations and glycosylations. Although known as powerful antibiotics containing potent antifungal activities (along with additional activities against parasites, enveloped viruses and prion diseases), their high toxicity toward mammalian cells and poor distribution in tissues have led to the continuous identification and structural modification of polyene macrolides to expand their general uses. Advances in in-depth investigations of the biosynthetic mechanism of polyene macrolides and the genetic manipulations of the polyene biosynthetic pathways provide great opportunities to generate new analogues. Recently, a novel class of polyene antibiotics was discovered (a disaccharide-containing NPP) that displays better pharmacological properties such as improved water-solubility and reduced hemolysis. In this review, we summarize the recent advances in the biosynthesis, pathway engineering, and regulation of polyene antibiotics in actinomycetes. [ABSTRACT FROM AUTHOR]

Polyene antibiotics such as nystatin are a large family of very valuable antifungal polyketide compounds typically produced by soil actinomycetes. Previously, using a polyene cytochrome P450 hydroxylase-specific genome screening strategy, Pseudonocardia autotrophica KCTC9441 was determined to contain an approximately 125.7-kb region of contiguous DNA with a total of 23 open reading frames, which are involved in the biosynthesis and regulation of a structurally unique polyene natural product named NPP. Here, we report the complete structure of NPP, which contains an aglycone identical to nystatin and harbors a unique di-sugar moiety, mycosaminyl-(α1-4)- N-acetyl-glucosamine. A mutant generated by inactivation of a sole glycosyltransferase gene ( nppDI) within the npp gene cluster can be complemented in trans either by nppDI-encoded protein or by its nystatin counterpart, NysDI, suggesting that the two sugars might be attached by two different glycosyltransferases. Compared with nystatin (which bears a single sugar moiety), the di-sugar containing NPP exhibits approximately 300-fold higher water solubility and 10-fold reduced hemolytic activity, while retaining about 50% antifungal activity against Candida albicans. These characteristics reveal NPP as a promising candidate for further development into a pharmacokinetically improved, less-cytotoxic polyene antifungal antibiotic. [ABSTRACT FROM AUTHOR]

Direct comparisons of different types of nanoparticles for drug delivery have seldom been performed. In this study we compare the physical properties and cellular activity of doxorubicin (Dox) conjugates to gold nanoparticles (Au) and InP quantum dots of comparable diameter. Although the Au particles alone are non-toxic and InP is moderately toxic, Au–Dox is more effective than InP–Dox against the Dox-resistant B16 melanoma cell line. Light exposure does not augment the efficacy of InP–Dox, suggesting that conjugates are breaking down. Electron and confocal microscopy and atomic absorption spectroscopy reveal that over 60% of the Au–Dox conjugates reach the cell nucleus. In contrast, InP–Dox enters cell nuclei to a very limited extent, although liberated Dox from the conjugates does eventually reach the nucleus. These observations are attributed to faster Dox release from Au conjugates under endosomal conditions, greater aggregation of InP–Dox with cytoplasmic proteins, and adherence of InP to membranes. These findings have important implications for design of active drug–nanoparticle conjugates. [ABSTRACT FROM AUTHOR]