In this review, we present a comprehensive summary of the formation of honeycomb microstructures and their applications, which include tissue engineering, antibacterial materials, replication processes or sensors. The history of the honeycomb pattern, the first experiments, which mostly involved the breath figure procedure and the improved phase separation, the most recent approach to honeycomb pattern formation, are described in detail. Subsequent surface modifications of the pattern, which involve physical and chemical modifications and further enhancement of the surface properties, are also introduced. Different aspects influencing the polymer formation, such as the substrate influence, a particular polymer or solvent, which may significantly contribute to pattern formation, and thus influence the target structural properties, are also discussed.

• Klíčová slova
• antibacterial properties, biopolymer, breath figure, honeycomb, improved phase separation, morphology, polymer, replication, surface modification, tissue engineering,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

This Rapid Communication presents a stochastic Wang tiling-based technique to compress or reconstruct disordered microstructures on the basis of given spatial statistics. Unlike the existing approaches based on a single unit cell, it utilizes a finite set of tiles assembled by a stochastic tiling algorithm, thereby allowing to accurately reproduce long-range orientation orders in a computationally efficient manner. Although the basic features of the method are demonstrated for a two-dimensional particulate suspension, the present framework is fully extensible to generic multidimensional media.

• MeSH
• algoritmy MeSH
• biofyzika metody   MeSH
• komprese dat MeSH
• počítačové zpracování obrazu MeSH
• reprodukovatelnost výsledků MeSH
• statistické modely MeSH
• stochastické procesy MeSH
• testování materiálů MeSH
• zobrazování trojrozměrné metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The characterization of mechanical properties in soft three-dimensional (3D) printed materials at the microscale remains a significant challenge due to the lack of standardized methodologies. To address this issue, a microscale nanoindentation protocol for elastomeric 3D printed microstructures is developed, optimized, and benchmarked. Herein, a conospherical indenter tip (r = 10.26 µm), a modified trapezoidal displacement profile with lift-off segments to capture adhesion interactions, and the nano-Johnson-Kendall-Roberts model for data analysis are employed. The protocol is optimized and verified using four newly developed polydimethylsiloxane (PDMS)-based inks for two-photon 3D laser printing. The results are compared to a state-of-the-art literature protocol that uses a Berkovich tip and the Oliver-Pharr model. It is shown that adhesion forces play a significant role in mechanical properties overestimation, showing differences of up to 80% between the different protocols. This study highlights the importance of carefully selecting characterization protocol to yield comparable results between studies. By providing a standardized protocol, it paves the way for straightforward and accurate characterization of mechanical properties in soft 3D printed materials at the microscale.

• Klíčová slova
• PDMS, additive manufacturing, elastomers, mechanical properties, nanoindentation, two‐photon polymerization,
• Publikační typ
• časopisecké články MeSH

Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials can provide insight into their processing, structure, and performance. To demonstrate the imaging capability of X-rays from an LWFA we have examined an irregular eutectic in the aluminum-silicon (Al-Si) system. The lamellar spacing of the Al-Si eutectic microstructure is on the order of a few micrometers, thus requiring high spatial resolution. We present comparisons between the sharpness and spatial resolution in phase contrast images of this eutectic alloy obtained via X-ray phase contrast imaging at the Swiss Light Source (SLS) synchrotron and X-ray projection microscopy via an LWFA source. An upper bound on the resolving power of 2.7 ± 0.3 μm of the LWFA source in this experiment was measured. These results indicate that betatron X-rays from laser wakefield acceleration can provide an alternative to conventional synchrotron sources for high resolution imaging of eutectics and, more broadly, complex microstructures.

• Publikační typ
• časopisecké články MeSH

The application of metal oxides in industries has been strengthened by the emergence of perovskite-based materials like bismuth titanates (Bi4Ti3O12 -BTO). They display new functionalities coupled with several mechanisms like doping engineering, crystalline and microstructure. Recently, the research on BTO with other doping elements has moved toward enhanced microstructural applications. This article mainly focuses on recent developments in the fabrication methods, crystal structure and microstructural analysis of BTO materials with doping elements. The excellent microstructure, easy synthesis methods, high chemical stability, good optical efficiency, and perfect doping made this material attractive. The crystal structure transition is analyzed. This review contemplates the current research on various BTO-based materials. A detailed discussion on grain size density measurements is given. This work concludes by establishing the future perspectives, challenges and present industrial applications of BTO.

• Klíčová slova
• Aurivillius, Bi(4)Ti(3)O(12), Crystal structure, Doping, Microstructure, Phase transition,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The usage of three-dimensional (3D) printed materials in many bioapplications has been one of the fastest-growing sectors in the nanobiomaterial industry in the last couple of years. In this work, we present a chemical approach for grafting silver nanoparticles (AgNPs) into a resin matrix, which is convenient for 3D printing. In this way, the samples can be prepared and are able to release silver ions (Ag+) with excellent antibacterial effect against bacterial strains of E. coli and S. epidermidis. By the proposed process, the AgNPs are perfectly mixed and involved in the polymerization process and their distribution in the matrix is homogenous. It was also demonstrated that this approach does not affect the printing resolution and the resin is therefore suitable for the construction of microstructures enabling controlled silver ion release and antifouling properties. At the same time the physical properties of the material, such as viscosity and elasticity modulus are preserved. The described approach can be used for the fabrication of facile, low-cost 3D printed resin with antifouling-antibacterial properties with the possibility to control the release of Ag+ through microstructuring.

• Klíčová slova
• CAD/CAM, antibacterial activity, antifouling properties, biomaterial, diazonium salt, silver nanoparticles,
• Publikační typ
• časopisecké články MeSH

The precopulatory behaviour of the larviform females of Ripidius quadriceps Abeille de Perrin, 1872 is described. The calling posture of virgin females is documented. The cephalic morphology and microstructures are visualised using scanning electron microscopy, in particular the secretory pores in the cuticle of inflatable maxillary palps. An exhaustive overview of relevant publications revealed that the location of secretory pores on the head of females is unique within the order Coleoptera. Compared to other beetles with sedentary calling females, the calling phase of the short-lived and non-feeding female of Ripidius is exceptionally short. For bioassays, various traps using virgin females of Ripidius were tested. It is likely that the sedentary behaviour of the short-lived female combined with a unique morphology and priority for investing in reproduction is compensated for by the actively flying males with remarkably flabellate antennae. The life cycle of this species, including some of the exceptions recorded at the individual level, is discussed. Perspectives for a biological and morphological survey of this rarely collected western Palaearctic species are outlined. In addition, the calling behaviour, secretory sites and location of pheromone glands in females of Coleoptera producing long range pheromones is reviewed.

• Klíčová slova
• Ripiphoridae, pheromone glands in females, scanning electronic microscopy, secretory pores and sensilla,
• MeSH
• brouci anatomie a histologie   růst a vývoj   ultrastruktura   MeSH
• hlava anatomie a histologie   MeSH
• rozmnožování MeSH
• stadia vývoje * MeSH
• vokalizace zvířat fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Megasecoptera are insects with haustellate mouthparts and petiolate wings closely related to Palaeodictyoptera and one of the few insect groups that didn't survive the Permian-Triassic mass extinction. Recent discovery of Brodioptera sinensis in early Pennsylvanian deposits at Xiaheyan in northern China has increased our knowledge of its external morphology using conventional optical stereomicroscopy. Environmental scanning electron microscopy (ESEM) of structures, such as antennae, mouthparts, wing surfaces, external copulatory organs and cerci have shed light on their micromorphology and supposed function. A comparative study has shown an unexpected dense pattern of setae on the wing membrane of B. sinensis. In addition, unlike the results obtained by stereomicroscopy it revealed that the male and female external genitalia clearly differ in their fine structure and setation. Therefore, the present study resulted in a closer examination of the microstructure and function of previously poorly studied parts of the body of Paleozoic insects and a comparison with homologous structures occurring in other Palaeodictyopteroida, Odonatoptera and Ephemerida. This indicates, that the role and presumptive function of these integumental protuberances is likely to have been a sensory one in the coordination of mouthparts and manipulation of stylets, escape from predators, enhancement of aerodynamic properties and copulatory behaviour.

• MeSH
• anatomické struktury zvířat fyziologie   ultrastruktura   MeSH
• hmyz klasifikace   fyziologie   ultrastruktura   MeSH
• skenovací elektrochemická mikroskopie MeSH
• zkameněliny * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Parylene-based implants or coatings introduce surfaces suffering from bacteria colonization. Here, we synthesized polyvinylpyrrolidone-stabilized selenium nanoparticles (SeNPs) as the antibacterial agent, and various approaches are studied for their reproducible adsorption, and thus the modification of parylene-C-coated glass substrate. The nanoparticle deposition process is optimized in the nanoparticle concentration to obtain evenly distributed NPs on the flat parylene-C surface. Moreover, the array of parylene-C micropillars is fabricated by the plasma etching of parylene-C on a silicon wafer, and the surface is modified with SeNPs. All designed surfaces are tested against two bacterial pathogens, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The results show no antibacterial effect toward S. aureus, while some bacteriostatic effect is observed for E. coli on the flat and microstructured parylene. However, SeNPs did not enhance the antibacterial effect against both bacteria. Additionally, all designed surfaces show cytotoxic effects toward mesenchymal stem cells at high SeNP deposition. These results provide valuable information about the potential antibacterial treatment of widely used parylene-C in biomedicine.

• Klíčová slova
• antimicrobial, biocompatibility, micropillars, parylene-C, selenium nanoparticles,
• Publikační typ
• časopisecké články MeSH

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

• Publikační typ
• tisková chyba MeSH