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[This corrects the article on p. e37152 in vol. 7.].

Steels represent the most widely-used metallic alloy, possessing a wide range of microstructures and mechanical properties. By examining the mechanical properties of steels in conjunction with microstructure this book provides a valuable description of the development and behavior of these materials, the very foundation of their widespread use. Updated throughout and including new chapters on nanostructured steels, and new alloys and technologies for the energy and automobile industries, the book is clearly written and illustrated, with extensive bibliographies and real-life examples. This is an essential reference, both compact and readily comprehensive, for metallurgists and engineers, as well as senior undergraduate students and postgraduates in materials science, physical metallurgy and mechanical engineering.

We apply a deep convolutional neural network segmentation model to enable novel automated microstructure segmentation applications for complex microstructures typically evaluated manually and subjectively. We explore two microstructure segmentation tasks in an openly available ultrahigh carbon steel microstructure dataset: segmenting cementite particles in the spheroidized matrix, and segmenting larger fields of view featuring grain boundary carbide, spheroidized particle matrix, particle-free grain boundary denuded zone, and Widmanstätten cementite. We also demonstrate how to combine these data-driven microstructure segmentation models to obtain empirical cementite particle size and denuded zone width distributions from more complex micrographs containing multiple microconstituents. The full annotated dataset is available on materialsdata.nist.gov.

Duplex stainless steels (DSS) are dual-phase alloys, consisting of both austenitic and ferritic phases in the microstructure. This unique structure provides an optimal balance between mechanical properties and corrosion resistance. Welding of DSS leads to changes in the microstructure and properties of the weld joints. In this study, an innovative laser welding method utilizing a dual beam approach was employed. By distributing the laser energy across two spots, additional heat is introduced into the weld, resulting in a reduction of the cooling rate during the welding process. The influence of laser focus on the microstructure and mechanical properties of the weld joints was investigated. The energy distribution of the dual beam was set at a 50:50 ratio, with the total weld energy remaining constant. Quantitative metallography was used to determine the ferrite/austenite ratio in the fusion zone. The mechanical properties of the welded joints were characterized by measuring shear strength and toughness within the fusion zone. For accurate determination of the maximum pressure force, the sensor was calibrated accordingly. The best results were achieved in the case of focal position 0 mm.

The chirality of (nano)structures is paramount in many phenomena, including biological processes, self-assembly, enantioselective reactions, and light or electron spin polarization. In the quest for new chiral materials, metallo-organic hybrids have been attractive candidates for exploiting the aforementioned scientific fields. Here, we show that chiral carbon nanoparticles, called carbon nanodots, can be readily prepared using hydrothermal microwave-assisted synthesis and easily purified. These particles, with a mean particle size around 3 nm, are highly soluble in water and display mirror-image profile both in the UV–Vis and in the infrared regions, as detected by electronic and vibrational circular dichroism, respectively. Finally, the nanoparticles are used as templates for the formation of chiral supramolecular porphyrin assemblies, showing that it is possible to use and transfer the chiral information. This simple (and effective) methodology opens up exciting opportunities for developing a variety of chiral composite materials and applications. A promising and efficient route to chiral materials involves the transfer of chirality across length scales. Here, the authors use chiral molecular precursors to synthesize chiral carbon nanodots, which in turn can template the formation of chiral supramolecular assemblies.

The method and results of evaluating the kinetics of austenite isothermal decomposition in austempered ductile iron (ADI) samples are presented based on the dimensional changes in austenitized and isothermally hardened cast iron samples. Experimental measurements were carried out on samples intended for the production of ADI castings under industrial conditions of ODLEWNIE POLSKIE S.A. A partial solution of the Kolmogorov–Johnson–Mehl–Avrami statistical theory of phase transformations as proposed by Avrami was applied to analyze the experimental results of dilatometric measurements. It is shown that Avrami diagrams can be used to evaluate changes in the kinetics of phase transformations occurring in ADI samples during the first stage of isothermal austenite decomposition. The application of the proposed method has made it possible to identify three steps of ausferrite growth during the first stage, with two statistically significant slowdowns. Using quantitative metallography methods, it is demonstrated that the slowdown in the rate of austenite decomposition during the transition from the first to the second step is related to the development of the microstructure of the metallic matrix of cast iron.

Natural enzymes contain highly evolved active sites that lead to fast rates and high selectivities. Although artificial metalloenzymes have been developed that catalyze abiological transformations with high stereoselectivity, the activities of these artificial enzymes are much lower than those of natural enzymes. Here, we report a reconstituted artificial metalloenzyme containing an iridium porphyrin that exhibits kinetic parameters similar to those of natural enzymes. In particular, variants of the P450 enzyme CYP119 containing iridium in place of iron catalyze insertions of carbenes into C-H bonds with up to 98% enantiomeric 1 excess, 35,000 turnovers, and 2550 hours⁻¹ turnover frequency. This activity leads to intramolecular carbene insertions into unactivated C-H bonds and intermolecular carbene insertions into C-H bonds. These results lift the restrictions on merging chemical catalysis and biocatalysis to create highly active, productive, and selective metalloenzymes for abiological reactions.

Due to their superior tolerability and efficacy, β-lactams are the most potent and prescribed class of antibiotics in the clinic. The emergence of resistance to those antibiotics, mainly due to the production of bacterial enzymes called β-lactamases, has been partially solved by the introduction of β-lactamase inhibitors, which restore the activity of otherwise obsolete molecules. This solution is limited because currently available β-lactamase inhibitors only work against serine β-lactamases, whereas metallo-β-lactamases continue to spread, evolve, and confer resistance to all β-lactams, including carbapenems. Furthermore, the increased use of antibiotics to treat secondary bacterial pneumonia in severely sick patients with COVID-19 might exacerbate the problem of antimicrobial resistance. In this Personal View, we summarise the main advances accomplished in this area of research, emphasise the main challenges that need to be solved, and the importance of research on inhibitors for metallo-B-lactamases amidst the current pandemic.

Klebsiella pneumoniae is a Gram-negative opportunistic pathogen responsible for a variety of community and hospital infections. Infections caused by carbapenem-resistant K. pneumoniae (CRKP) constitute a major threat for public health and are strongly associated with high rates of mortality, especially in immunocompromised and critically ill patients. Adhesive fimbriae, capsule, lipopolysaccharide (LPS), and siderophores or iron carriers constitute the main virulence factors which contribute to the pathogenicity of K. pneumoniae. Colistin and tigecycline constitute some of the last resorts for the treatment of CRKP infections. Carbapenemase production, especially K. pneumoniae carbapenemase (KPC) and metallo-β-lactamase (MBL), constitutes the basic molecular mechanism of CRKP emergence. Knowledge of the mechanism of CRKP appearance is crucial, as it can determine the selection of the most suitable antimicrobial agent among those most recently launched. Plazomicin, eravacycline, cefiderocol, temocillin, ceftolozane–tazobactam, imipenem–cilastatin/relebactam, meropenem–vaborbactam, ceftazidime–avibactam and aztreonam–avibactam constitute potent alternatives for treating CRKP infections. The aim of the current review is to highlight the virulence factors and molecular pathogenesis of CRKP and provide recent updates on the molecular epidemiology and antimicrobial treatment options.

Several experiments have shown a huge enhancement in thermal radiation over the blackbody limit when two objects are separated by nanoscale gaps. Although those measurements only demonstrated enhanced radiation between homogeneous materials, theoretical studies now focus on controlling the near-field radiation by tuning surface polaritons supported in nanomaterials. Here, we experimentally demonstrate near-field thermal radiation between metallo-dielectric multilayers at nanoscale gaps. Significant enhancement in heat transfer is achieved due to the coupling of surface plasmon polaritons (SPPs) supported at multiple metal-dielectric interfaces. This enables the metallo-dielectric multilayers at a 160-nm vacuum gap to have the same heat transfer rate as that between semi-infinite metal surfaces separated by only 75 nm. We also demonstrate that near-field thermal radiation can be readily tuned by modifying the resonance condition of coupled SPPs. This study will provide a new direction for exploiting surface-polariton-mediated near-field thermal radiation between planar structures. Here, the authors report on an experimental demonstration of near-field thermal radiation enhancement between metallo-dielectric multilayers separated by submicron gap distances and that near-field thermal radiation can be readily tuned by modifying the resonance condition of coupled surface plasmon polaritons.