Mrs Bulletin最新文献

A triboelectric nanogenerator (TENG) is a novel device that utilizes contact electrification and electrostatic induction to convert mechanical energy into electrical energy. Its characteristics include high energy density and flexibility, enabling self-powering of electronic devices by harvesting mechanical energy from the environment. Its applications include biomedical devices, wearable electronics, and Internet-of-Things (IoT) sensors. Despite these advantages, extracting electrical energy from TENG remains challenging due to its time-varying nature and low internal capacitance. Effective power-management techniques are essential for TENG energy-harvesting systems, yet research on dedicated integrated power-conversion methods is currently limited. Given the growing interest in TENG, a comprehensive exploration of energy-harvesting systems is critically necessary. This article synthesizes and compares current advancements in triboelectric energy-harvesting systems, emphasizing strategies to enhance output power through various power-conversion techniques. Additionally, it explores techniques employed in other energy-harvesting systems to inspire innovative approaches in TENG system design.

Graphical abstract:

Abstract: Filamentous cyanobacteria originate toxic harmful algal blooms (HABs) in aquatic ecosystems, severely impacting freshwater ecosystems and life. Despite being natural bloomers, these microorganisms are challenging to handle in vitro, due to the formation of aggregates with entangled filaments. Consequently, their precise growth dynamics, although vital to timely predict HABs, remains inaccessible. Here, we precisely assessed growth of the HAB forming cyanobacteria Oscillatoria nigroviridis, by cultivating filament suspensions in transparent, gas permeable, and portable fluoropolymer microcapillary strips. Direct optical observation of O. nigroviridis growth revealed shorter filaments comprising less than 50 cells grew at a slower rate, dN/dt = 0.09 cell/day compared to filaments comprising more than 50 cells, with dN/dt up to 0.47 cell/day. The fourfold increase in dN/dt is suggested as part of the blooming strategy of the microorganism. This work suggests that fluoropolymer microcapillary strips can be used for effortless sampling and high-resolution monitoring of HABs.

Impact statement: Climate change is increasing the occurrence of episodes of harmful algal bloom, where uncontrolled growth of noxious cyanobacteria such as Oscillatoria species has detrimental outcomes in both the environment and biomass production industry, consequently, impairing human and animal health due to the production of toxic or bioactive compounds. In particular, the study of growth dynamics of Oscillatoria species has been limited to unprecise methods due to complications with aliquoting filamentous biomass. Fluoropolymer microcapillary strips provide an ideal miniaturized platform for sampling, cultivation, and growth monitoring of O. nigroviridis strain UHCC 0327, which paves the way to foster better water quality management tools.

Graphical abstract:

Supplementary information: The online version contains supplementary material available at 10.1557/s43577-024-00813-7.

We report on a 23-year-old man who presented with bilateral subclinical keratoconus and juvenile glaucoma (JG). With intraocular pressures (IOPs) of 30 and 28 mmHg, both eyes were consecutively operated by adjusted trabeculotomy, leading to a remarkable decrease in IOP to well below the mean for this surgery in JG. Meanwhile, most keratoconus indices clearly progressed in the first 5 months postoperatively, with increases in corneal hysteresis, associated with a remarkable drop in the corneal resistance factor. During the following years, IOP remained low, and all changes (except the increase in corneal hysteresis) reverted to near preoperative levels through the follow-up course of 5 years. This report complements a few existing reports that show the coincidence of keratoconus and JG, and, more importantly, documents a novel pattern of remarkable and prolonged corneal changes following surgical lowering of IOP in eyes with these changes. Postoperative biomechanical disturbances in the cornea and possibly limbus are proposed in cases of JG and subclinical keratoconus.

The natural world contains a diverse range of solutions that allows for living organisms to dynamically adapt their structure and mechanical properties to meet environmental demands. For example, coral reef is able to accumulate reinforcing calcium carbonate from wave agitation and water current that stabilizes gaps in the structure and increases the reef density and strength through diagenetic reef cementation. Bone responds to repeated stress by translating deformations and fluid movement in the bone matrix into cellular signals that trigger bone formation through mechanotransduction. Utilizing these mechanisms as inspiration, synthetic materials have been developed that utilize stress-generated piezoelectric charges to attract mineral ions to form reinforcing mineral layers that can repair defects and damage over time and extend material lifetime. In this article, we examine natural adaptive processes that give inspiration for new synthetic materials with similar dynamic adaptive properties. We also introduce the capabilities of existing bioinspired synthetic materials, current challenges these systems face, potential application areas of this technology, and future research opportunities of these adaptive materials.

Graphical abstract

Abstract

Metallic materials, predominantly steels, are the most common structural materials in the various components along the hydrogen supply chain. Ensuring their sustainable and safe use in hydrogen technologies is a key factor in the ramp-up of the hydrogen economy. This requires extensive materials qualification, however, most of the accepted; and standardized test methods for determining the influence of gaseous hydrogen on metallic materials describe complex and costly procedures that are only available to a very limited extent worldwide. The hollow specimen technique is a simple, rapid, and economical method designed to overcome the limitations of the current methods for the qualification of metallic materials under high-pressure hydrogen gas. However, this technique is not yet standardized. The TransHyDE-H2Hohlzug project is presented in this article, along with the main steps required to optimize the hollow specimen technique. This includes closing knowledge gaps related to the specimen geometry, surface quality, and gas purity in dedicated working packages, thus contributing to a comprehensive standardization of the technique for tests in high-pressure hydrogen gas.

Impact statement

The hydrogen economy is considered a key solution for achieving climate neutrality in Europe, as it plays a crucial role in the decarbonization of sectors such as transport, industry, power, etc. Ensuring the safety and reliability of infrastructure is crucial for the ramp-up of the hydrogen economy. Therefore, it is necessary to meticulously study the materials and components used for infrastructure under conditions that closely resemble in-service conditions. The currently standardized methods are limited as they do not precisely replicate in-service conditions, and when they do, they are often complex, costly, and not easily accessible. This article presents the hollow specimen technique, a simple, and economical method developed to address the limitations of current standardized methods. The results from this work will contribute to the standardization of this technique for tests in high-pressure hydrogen gas. This will enable a faster evaluation of materials for hydrogen applications by industry and academia, thereby contributing to the growth of the hydrogen economy.

Graphical abstract

Abstract

This study investigated the precipitation strengthening of chemically disordered Cu-rich phase and its effect on the mechanical properties of Cu-doped Fe18Cr14Ni3Mo austenitic steels. A high density of Cu-rich nanoprecipitates with fully coherent structure were formed in the austenitic matrix. These nano-sized Cu-rich nanoprecipitates improved the strength of alloys by hindering the movement of grain boundaries, revealing the disordering strengthening effect. Meanwhile, dense precipitates prevented grain growth, thereby improving grain refinement and further increasing the strength. Particularly, samples with Cu alloying exhibited a more pronounced grain refinement effect on grain-refined samples compared to ones without alloying, thus showing a more significant strengthening effect. The findings of this study not only offer guidance for the design of high-strength materials via disordering effects but also provide new insights in fabricating the ultrafine grain materials.

Impact statement

In this study, we successfully prepared forged austenitic steels with Cu-rich phases via a cold rolling process. Dense Cu-rich phases improved alloy strength by hindering dislocation movement and preventing grain growth, leading to grain refinement. The influence of Cu-rich phase precipitation on mechanical properties and microstructures of Fe18Cr14Ni3Mo4Cu austenitic steels, both virgin and grain-refined, was systematically analyzed and compared. Results showed that mechanical property enhancement in Cu-doped samples was mainly due to grain-refinement and precipitation strengthening. Notably, the role of Cu-rich phases in grain refinement became more significant after cold rolling. Compared to the grain-refined undoped Cu samples, the average grain size of the Cu-doped grain-refined samples was reduced by a factor of 3.2, and the yield strength was increased by a factor of 1.4, demonstrating the effect of Cu-rich phases in preventing grain growth and achieving grain refinement.

Graphical abstract

Abstract

Spider silk is an archetypal biopolymer material with extreme tensile properties arising from its complex hierarchical assembly. While recent advances in sequencing have yielded abundant insights, relatively little is known concerning post-translational modifications (PTMs) in spider silk. Here, we probe the PTM landscape of dragline silk from the Jorō spider (Trichonephila clavata) using a combination of mass spectroscopy and solid-state nuclear magnetic resonance (NMR). The results reveal a wide array of potential modifications, including hydroxyproline, phosphorylation, and dityrosine cross-links, encompassing the different spidroin constituents. Notably, the MaSp3 repetitive region displayed numerous PTMs, whereas MaSp1 and MaSp2 variants showed distinct phosphorylation patterns in its terminal domains. The N-terminal domain (NTD) phosphorylation sites were found predominantly at the dimer interface, suggesting a modulatory function with respect to its pH-driven dimerization function, a hypothesis supported by studies using phosphomimetic NTD mutants. Possible roles of phosphoserine in limiting β-sheet formation, and hydroxyproline in disrupting β-turns are also discussed.

Impact statement

Spider silk is an archetypal biomaterial that can outperform our most sophisticated artificial fibers. The secret to its mechanical properties lies in its complex hierarchical structure—encompassing the nano- to macroscales—that forms through a process of molecular self-assembly of the constituent spidroin proteins. While recent advances in "biomateriomics” have given us tremendous insights into the sequence–function relationships that determine spider silk behavior, the picture is still far from complete. One area that has received little attention is posttranslational modifications (PTMs). PTMs are ubiquitous biological phenomena that are crucial for providing dynamic control of the proteome, and effectively expand the structural and functional design space of proteins beyond that provided by the canonical amino acids. Here, we undertook a comprehensive analysis of PTMs from spider dragline silk fiber, which revealed numerous potential sites for a wide array of modifications. The results provide a fascinating window into additional layers of complexity underlying the mechanical behavior of spider silk, and suggest further avenues for creating novel, dynamically tunable, bioinspired materials.

Graphical abstract

Hybrid halide perovskites (HPs) are emerging as the most promising materials for near-future photovoltaics (PV) due to their unique optoelectronic properties, such as their low defect density and broad absorption, making them highly efficient photoactive materials. Meanwhile, their low cost and low embodied energy, together with their solution processability and the possibility to create solar cells on flexible substrates, make them among the potential winning concepts for the next-generation PV market. Large-scale marketing, however, requires solving current challenges, which mainly relate to device longevity and scaling up. In this article, we put in perspective the key aspects of HP materials and HP-solar cells, briefly discussing their historical path to high efficiency, reviewing the state of the art, presenting their main advantages over existing technologies, and the main challenges the research community needs to overcome. Recent achievements and hot areas today critical for market uptake will be presented.

Graphical abstract

An exciton is a bound pair of negatively charged electron and positively charged hole (electron vacancy within a solid), both of which are held together by their mutual Coulomb attraction to form a bound state. One hundred years after their discovery, excitons act as the backbone of a large class of low-dimensional and quantum materials showing a truly “exotic” set of physical, chemical as well as biophysical properties. In this issue of MRS Bulletin, we designate all such materials whose properties are crucially dependent on the presence of these excitons as “Excitonic materials.” Current studies of these materials are progressing rapidly in newer directions, including those in novel materials and next-generation technologies. Therefore, the main focus of this issue is to catch recent progresses in the physics of “excitons” and “excitonic materials,” encompassing both fundamental understandings of the nature of these quasiparticles and their emerging device applications in various fields. This article is an overview of this issue, recalling the basics of exciton physics, the historical contexts, and recent progresses without claiming to be exhaustive.

Graphical Abstract

Within the last few years, Rydberg excitons, bound electron–hole pairs in highly excited states, have emerged as a promising technology platform for quantum nonlinear optics, quantum information processing, and quantum sensing. The advanced device designs and sensing concepts in these fields require strong nonlinearities at the few-photon or few-carrier level. Rydberg states offer the required strong nonlinearities as the relevant physical quantities at the heart of such nonlinear effects scale strongly with the principal quantum number, n, of the excited state: For example, their polarizability scales as (n^7), resulting in an enormous sensitivity to external fields. We review recent experimental and theoretical results that pave the way toward quantum sensing of the electric fields originating from static charge carriers and strongly diluted electron–hole plasmas. We also discuss the strong nonlinear optical properties of Rydberg excitons and how they could be utilized in terms of sensing.

Graphical abstract