Electron Microscopy Data Research Articles

Mineral Liberation and Concentration Characteristics of Apatite Comminuted by High-Pressure GRU

Mineral liberation and concentration have always been the core issues in ore processing. The goal of multi-stage crushing and ball milling is liberation because mineral liberation is the foundation of beneficiation. High energy consumption and environmental pollution have always been unavoidable topics. We put forward the method of high-pressure gas rapid unloading (GRU). Particle size followed MR-R distribution. The scanning electron microscopy data showed that the liberation of apatite particles smaller than 4 mm was sufficient by high-pressure GRU methods, and high-grade apatite concentrated in the particle size range of 0.5 to 4 mm. The average grade of the preferred particle size interval was 3%–5% higher than the original ore. Liberation degrees of apatite less than 4 mm are above 88%, which was beneficial for mineral processing. Compared to the traditional crushing method, the GRU method had a higher liberation and concentration in the particle size range of 0.5 to 4 mm. The total energy consumption was about 1.76 kW·h/t, less than that of the traditional crushing method.

Electron microscopy method in assessing the quality of cell cryopreservation

During its existence, electron microscopy has become one of the reference methods for assessing the structural and functional state of cells, tissues and organs, and an extensive evidence base has been formed that allows its use in the creation and formation of a biobank. The selection of sources for the literature review was carried out using keywords based on publications over the past 20 years. The publications presented in the review were selected by searching the eLIBRARY.RU, PubMed and Scopus databases. Based on foreign and domestic experience in the work of biobanks, we can distinguish four areas that determine the effectiveness of the use of electron microscopy studies as a component of its work. Firstly, it is control of microbiological contamination of a biological sample. The effectiveness of electron microscopy in detecting contamination of a biological sample with bacteria, fungi and viruses is comparable to the effectiveness of classical microbiological techniques. Secondly, it is a diagnostic tool that allows you to identify or confirm the presence in a sample of a pathogenetic process that is of interest for biobanking: tumor growth, atherosclerotic vessel damage, etc. Thirdly, it is quality control for cryopreservation of samples. A wide range of morphological characteristics of the ultramicroscopic structure of cells and microanatomical formations makes it possible to characterize the quality of cryopreservation and quantify the degree of damage, which contributes to the unification and standardization of biobanking. Transmission electron microscopy is the most informative in this matter. Fourthly, this is the basis for digitalization of the results obtained and the formation of an interdisciplinary biobank repository, which allows the use of “big date” technologies for fundamental research. The compliance of the biobank profile with the economic, scientific and industrial characteristics of the infrastructure of the industry or region is of great importance. Electron microscopy data are successfully combined with the results of molecular studies, which allows the formation of interdisciplinary metadata databases suitable for interregional and interdisciplinary scientific integrations. The latter makes it possible to use electron microscopy data to solve a wide range of applied and interdisciplinary problems. The above allows us to consider scanning and transmission microscopy methods as one of the key methods in the development of biobanking in the region.

Integration by design: driving mineral system knowledge using multi-modal, collocated, scale-consistent characterisation

Abstract. Recent decades have seen an exponential rise in the application of machine learning in geoscience. However, fundamental differences distinguish geoscience data from most other data types. Geoscience datasets are typically multi-dimensional, and contain 1D (drill holes), 2D (maps or cross-sections), and 3D volumetric and point data (models/voxels). Geoscience data quality is a product of the data's resolution and the precision of the methods used to acquire them. The dimensionality, resolution, and precision of each layer within a geoscience dataset translate into limitations to the spatiality, scale, and uncertainty of resulting interpretations. Historically, geoscience datasets were overlaid cartographically to incorporate subjective, experience-driven knowledge and variances in scale and resolution. These nuances and limitations that underpin the reliability of automated interpretation are well understood by geoscientists but are rarely appropriately transferred to data science. For true integration of geoscience data, such issues cannot be overlooked without consequence. To apply data analytics to complex geoscience data (e.g. hydrothermal mineral systems) effectively, methodologies that characterise the system quantitatively at a common scale, using collocated analyses, should be sought. This paper provides research and exploration insights from an innovative district-wide, scale-integrated geoscience data project, which analysed 1590 samples from 23 mineral deposits and prospects across the Cloncurry district, Queensland, Australia. Nine different analytical techniques were used, including density, magnetic susceptibility, remanent magnetisation, anisotropy of magnetic susceptibility, radiometrics, conductivity, automated mineralogy based on scanning electron microscopy (SEM), geochemistry, and short-wave infrared (SWIR) hyperspectral data with 561 columns of scale-integrated data (+2151 columns of SWIR data). All data were collected on 2.2 cm × 2.5 cm sample cylinders, a scale at which the confidence in the coupling of data from techniques can be high. These data are integrated by design to eliminate the need to downscale coarser measurements via assumptions, inferences, inversions, and interpolations. This scale-consistent approach is critical to the quantitative characterisation of mineral systems and has numerous applications in mineral exploration, such as linking alteration paragenesis with structural controls and petrophysical zonation. The Cloncurry METAL dataset is made freely available via the AuScope Data Repository: https://doi.org/10.60623/82trleue (Austin et al., 2024).

RETRACTION: High-Resolution Imaging of Human Cancer Proteins Using Microprocessor Materials.

M. J. Solares, G. M. Jonaid, W. Y. Luqiu, S. Berry, J. Khadela, Y. Liang, M. C. Evans, K. J. Pridham, W. J. Dearnaley, Z. Sheng and D. F. Kelly, "High-Resolution Imaging of Human Cancer Proteins Using Microprocessor Materials," ChemBioChem, 23, no. 17 (2022), e202200310, https://doi.org/10.1002/cbic.202200310. The above article, published online on 5 July 2022 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Ruben Ragg; and Wiley-VCH GmbH. The retraction has been agreed following a thorough peer review process conducted by the author's institution, Penn State. The editors' own independent investigation confirmed that density map for the p53 dimer does not align well with the model for Figures 2B and S3 A. Furthermore, it was found that the coordinate and map files associated with the article available in the Protein Data Bank [PDB accession codes 8F2I (p53 monomer), 8F2H (p53 dimer)] and Electron Microscopy Data Bank [EMDB accession codes EMD28817 (p53 monomer), EMD28816 (p53 dimer)] exhibit poor alignment throughout. In addition, the authors did not provide original research data, maps and models in question, to justify the findings. The editors' own independent investigation confirmed that the conclusions of this manuscript are not sufficiently supported. Author D. F. Kelly responded to our notice of retraction, but did not state their agreement nor disagreement. Author G. M. Jonaid agrees with the retraction. All other authors did not respond to our notice regarding the retraction.

Detailing organelle division and segregation in Plasmodium falciparum.

The malaria-causing parasite, P. falciparum, replicates through schizogony, a tightly orchestrated process where numerous daughter parasites are formed simultaneously. Proper division and segregation of one-per-cell organelles, like the mitochondrion and apicoplast, are essential, yet remain poorly understood. We developed a new reporter parasite line that allows visualization of the mitochondrion in blood and mosquito stages. Using high-resolution 3D imaging, we found that the mitochondrion orients in a cartwheel structure, prior to stepwise, non-geometric division during last-stage schizogony. Analysis of focused ion beam scanning electron microscopy data confirmed these mitochondrial division stages. Furthermore, these data allowed us to elucidate apicoplast division steps, highlighted its close association with the mitochondrion, and showed putative roles of the centriolar plaques in apicoplast segregation. These observations form the foundation for a new detailed mechanistic model of mitochondrial and apicoplast division and segregation during P. falciparum schizogony and pave the way for future studies into the proteins and protein complexes involved in organelle division and segregation.

CryoSTAR: leveraging structural priors and constraints for cryo-EM heterogeneous reconstruction.

Resolving conformational heterogeneity in cryogenic electron microscopy datasets remains an important challenge in structural biology. Previous methods have often been restricted to working exclusively on volumetric densities, neglecting the potential of incorporating any preexisting structural knowledge as prior or constraints. Here we present cryoSTAR, which harnesses atomic model information as structural regularization to elucidate such heterogeneity. Our method uniquely outputs both coarse-grained models and density maps, showcasing the molecular conformational changes at different levels. Validated against four diverse experimental datasets, spanning large complexes, a membrane protein and a small single-chain protein, our results consistently demonstrate an efficient and effective solution to conformational heterogeneity with minimal human bias. By integrating atomic model insights with cryogenic electron microscopy data, cryoSTAR represents a meaningful step forward, paving the way for a deeper understanding of dynamic biological processes.

Cartilage Laser Engraving for Fast-Track Tissue Engineering of Auricular Grafts

In this study, the optimal engraving parameters were determined through the analysis of scanning electron microscopy (SEM) data, as follows: a laser power density of 5.5 × 105 W/cm2, an irradiation rate of 0.1 mm/s, a well radius of 60 μm, a distance between well centers of 200 μm, and a number of passes for each well of 20. After 1 week of in vitro cultivation, chondrocytes were located on the surface of the scaffolds, in the sockets and lacunae of decellularized cartilage. When implanted into animals, both cellular and acellular scaffolds were able to support cartilage in-growth and complete regeneration of the defect without clear boundaries with normal tissue. Nevertheless, the scaffolds populated with cells exhibited superior biocompatibility and were not subject to rejection, in contrast to cell-free constructs.

High-fidelity reconstruction of porous cathode microstructures from FIB-SEM data with deep learning

Accurate modeling of lithium-ion battery (LIB) electrode microstructures provides essential references for understanding degradation mechanisms and optimizing materials. Traditional segmentation methods often struggle to accurately capture the complex microstructures of porous LIB electrodes in focused ion beam scanning electron microscopy (FIB-SEM) data. In this work, we develop a deep learning model based on the Swin Transformer to segment FIB-SEM data of a lithium cobalt oxide electrode, utilizing fused secondary and backscattered electron images. The proposed approach outperforms other deep learning methods, enabling the acquirement of 3D microstructure with reduced particle elongated artifacts. Analyses of the segmented microstructures reveal improved electrode tortuosity and pore connectivity crucial for ion and electron transport, emphasizing the necessity of accurate 3D modeling for reliable battery performance predictions. These results suggest a path toward voxel-level degradation analysis through more sensible battery simulation on high-fidelity microstructure models directly twinned from real porous electrodes.

Bond-centric modular design of protein assemblies.

We describe a modular bond-centric approach to protein nanomaterial design inspired by the rich diversity of chemical structures that can be generated from the small number of atomic valencies and bonding interactions. We design protein building blocks with regular coordination geometries and bonding interactions that enable the assembly of a wide variety of closed and opened nanomaterials using simple geometrical principles. Experimental characterization confirms successful formation of more than twenty multi-component polyhedral protein cages, 2D arrays, and 3D protein lattices, with a high (10-50 %) success rate and electron microscopy data closely matching the corresponding design models. Because of the modularity, individual building blocks can assemble with different partners to generate distinct regular assemblies, resulting in an economy of parts and enabling the construction of reconfigurable systems.

Biogenic synthesis of AgNPs via polyherbal formulation: Mechanistic neutralization and toxicological impact on acetylcholinesterase from Bungarus sindanus venom.

This study aims to examine the biogenic production, characterization, and anti-acetylcholinesterase (AAChE) properties of polyherbal formulation PHF-extract-synthesized silver nanoparticles (PHF-AgNPs). The Elapidae snake Bungarus sindanus has extremely dangerous venom for humans and contains a high amount of AChE (acetylcholinesterase). Inhibiting AChE leads to acetylcholine buildup, affecting neurotransmission. The study tested silver nanoparticles as AChE inhibitors using kinetics. Their production was confirmed through ultraviolet (UV) spectrometry at 425 nm (SPR peak of 1.94), and stabilizing functional groups were identified via Fourier transform infrared spectroscopy (FT-IR). The average length of 20 nm was confirmed by analyzing the scanning electron microscopy (SEM) data. Energy-dispersive X-ray spectroscopy (EDX) identified silver as the primary component of PHF-AgNPs (26%). Statistical analysis showed that the activity of AChE in krait venom decreased by up to 45% and 37% at a given dose of ACh (0.5 mM) by PHF and AgNPs, respectively. Utilizing the Lineweaver-Burk plot for kinetic analysis, a competitive type of inhibition is found. RESEARCH HIGHLIGHTS: Successfully synthesized PHF-extract-induced silver nanoparticles (PHF-AgNPs) demonstrated through UV spectrometry and characterized as crystalline with an average size of 45 nm by X-ray diffraction. PHF-AgNPs effectively inhibited acetylcholinesterase (AChE), an enzyme critical in neurotransmission, reducing its activity in krait venom by up to 45% at certain concentrations. Kinetic analysis revealed that the inhibition mechanism of AChE by PHF-AgNPs is competitive, offering potential for therapeutic applications in neurologically related conditions.

Limosilactobacillus fermentum CGMCC 1.7434 and Debaryomyces hansenii GDMCC 2.149 synergize with ultrasound treatment to efficiently degrade nitrite in air-dried ducks

Nitrites in meat products are important food additives with coloring, antibacterial and antioxidant effects, but excessive intake of nitrites can pose health risks, including an increased risk of cancer due to the formation of carcinogenic nitrosamines. In the present study, Limosilactobacillus fermentum CGMCC 1.7434 was screened and the effects of it and Debaryomyces hansenii GDMCC 2.149 and their combination on nitrite degradation were investigated. It was found that the co-culture of L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 significantly enhanced nitrite degradation (99.58%). The findings on salt and ethanol tolerance suggest suitability for application in meat fermentation processes. Scanning electron microscopy and additional data indicate that D. hansenii GDMCC 2.149 facilitates the growth, acid production, adhesion, secretion of AI-2 signaling molecules, and biofilm formation of L. fermentum CGMCC 1.7434. Metabolomics analysis suggests that these microorganisms reduce nitrite levels by converting NH3 derived from nitrite into L-glutamine, which is further transformed into N-nitroso compounds and their downstream derivatives through the ABC transporter pathway, the TCA cycle, and the amino acid metabolism pathway. Microbial community analyses showed that L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 were successfully inoculated into air-dried ducks, becoming dominant strains and effectively inhibiting the growth of pathogenic bacteria. Furthermore, during the processing of air-dried duck, the combination of ultrasonic cavitation (250 W, 4 min, 30°C, 40 kHz) with the co-fermentation of L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 effectively reduced nitrite content (84.55%) and TVB-N levels in the meat, without compromising color or TBARS values. This is crucial for understanding the mechanism of nitrite degradation by LAB in synergy with yeast and for the advancement of low-nitrite air-dried duck products.

Controlling the quality of Patinopecten yessoensis from the perspective of the ultrasound and ferulic acid influences.

In this study, the effects of ultrasound combined with ferulic acid (FA) on the quality of the Yesso scallop (Patinopecten yessoensis) adductor muscles (SAM) during refrigerated storage were investigated. The results demonstrated that the combined treatment with 350W ultrasound and FA (UFA) significantly delayed enzyme activities and microbial growth in SAM tissues compared to FA treatment alone. After 6 days of cold storage, samples treated with UFA exhibited higher hardness (2850g), lower thiobarbituric acid reactive substances (TBARS=9.35 MDA mg/g SAM), and lower total volatile basic nitrogen (TVB-N=19.75mg/100g SAM) values compared to control and FA-treated samples. Consequently, UFA treatment prolonged the shelf life of SAM by 3 days during storage at 4°C. Based on scanning electron microscopy and low-field nuclear magnetic resonance data, these findings are attributed to UFA treatment not only reducing the degradation of SAM tissue network structure but also minimizing water loss. PRACTICAL APPLICATION: Scallop adductor muscle (SAM) is commonly considered a delicacy owing to its unique mouthfeel and delicious taste. However, owing to its high moisture content and high levels of various nutrients, SAM has a short shelf life. In this work, a combination of ultrasound with ferulic acid (UFA) has been found to have effective preservation effects on SAM during refrigerated storage. Our study findings pave the way for a potential approach to maintain scallop quality during processing and storage. Moreover, our study also provides some theoretical basis for using and promoting these technologies in aquatic products.

Nicotinamide mononucleotide supplementation rescues mitochondrial and energy metabolism functions and ameliorates inflammatory states in the ovaries of aging mice.

Noninvasive pharmacological strategies like nicotinamide mononucleotide (NMN) supplementation can effectively address age-related ovarian infertility by maintaining or enhancing oocyte quality and quantity. This study revealed that ovarian nicotinamide adenine dinucleotide levels decline with age, but NMN administration significantly restores these levels, preventing ovarian atrophy and enhancing the quality and quantity of ovulated oocytes. Improvements in serum hormone secretion and antioxidant factors, along with decreased expression of proinflammatory factors, were observed. Additionally, a significant increase in the number of ovarian follicles in aging individuals was noted. Scanning electron microscopy data indicated that NMN significantly alters the density and morphology of lipid droplets and mitochondria in granulosa cells, suggesting potential targets and mechanisms. Transcriptomic analysis and validation experiments collectively suggested that the beneficial effects of NMN on aging ovaries are mediated through enhanced mitochondrial function, improved energy metabolism, and reduced inflammation levels. Our results suggest that NMN supplementation could improve the health status of aging ovaries and enhance ovarian reserve, offering new insights into addressing fertility challenges in older women through assisted reproductive technology.

Optimized protocol for collecting root canal biofilms for in vitro studies

Endodontic retreatment is often necessitated by several factors, including the persistence of microorganisms in the root canal system (RCS). Their complex organization in biofilms increases their pathogenic potential, necessitating new disinfection strategies. This study aimed to standardize a new in vitro protocol for collecting biofilm from the RCS. Thirty-four bovine incisors were used in the study, divided into two experimental groups with two collection steps each: (a) biofilm collection protocol and (b) absorbent paper points protocol. Twelve specimens from each group were selected for counting colony-forming units (CFUs), while eight specimens were prepared for scanning electron microscopy (SEM). Two additional specimens served as sterilization controls to ensure that experiments were free of contamination. The coronal region was removed and standardized at 15 mm. After preparation with ProTaper up to F5, the apical foramen was sealed with composite resin, and the roots were stabilized with acrylic resin in 1.5-mL Eppendorf tubes. The specimens were sterilized and inoculated with Enterococcus faecalis NTCT 775 every 24 h for 21 days. After this period, each group underwent biofilm collection protocols, and CFU and scanning electron microscopy (SEM) data were analyzed. The Shapiro–Wilk test was performed to assess the normality of log-transformed data, and the results indicated a normal distribution for all groups, allowing parametric testing. The Levene test was used to evaluate the equality of variances. The proposed biofilm collection method yielded significantly higher CFU counts compared with the absorbent paper points method, particularly when analyzed on a log₁₀ scale. An independent samples t-test confirmed a statistically significant difference between the two methods (p < 0.0001). The proposed protocol achieved an efficiency rate of 95.85 % ± 1.15 %, whereas the absorbent paper points protocol yielded a lower efficiency of 5.46 % ± 1.37 %. Therefore, the biofilm collection protocol proposed in this study proved to be more effective for biofilm removal from the RCS.

Beyond neurons: computer vision methods for analysis of morphologically complex astrocytes

The study of the geometric organization of biological tissues has a rich history in the literature. However, the geometry and architecture of individual cells within tissues has traditionally relied upon manual or indirect measures of shape. Such rudimentary measures are largely a result of challenges associated with acquiring high resolution images of cells and cellular components, as well as a lack of computational approaches to analyze large volumes of high-resolution data. This is especially true with brain tissue, which is composed of a complex array of cells. Here we review computational tools that have been applied to unravel the cellular nanoarchitecture of astrocytes, a type of brain cell that is increasingly being shown to be essential for brain function. Astrocytes are among the most structurally complex and functionally diverse cells in the mammalian body and are essential partner cells of neurons. Light microscopy does not allow adequate resolution of astrocyte morphology, however, large-scale serial electron microscopy data, which provides nanometer resolution 3D models, is enabling the visualization of the fine, convoluted structure of astrocytes. Application of computer vision methods to the resulting nanoscale 3D models is helping reveal the geometry and organizing principles of astrocytes, but a complete understanding of astrocyte structure and its functional implications will require further adaptation of existing computational tools, as well as development of new approaches.

Nucleosome placement and polymer mechanics explain genomic contacts on 100kbp scales.

The 3d organization of the genome - in particular, which two regions of DNA are in contact with each other - plays a role in regulating gene expression. Several factors influence genome 3d organization. Nucleosomes (where ~ 100 basepairs of DNA wrap around histone proteins) also bend, twist and compactify chromosomal DNA, altering its polymer mechanics. How much does the positioning of nucleosomes between gene loci influence contacts between those gene loci? And, to what extent is polymer mechanics responsible for this? To address this question, we combine a stochastic polymer mechanics model of chromosomal DNA including twists and wrapping induced by nucleosomes with two data-driven pipelines. The first estimates nucleosome positioning from ATACseq data in regions of high accessibility. Most of the genome is low-accessibility, so we combine this with a novel image analysis method that estimates the distribution of nucleosome spacing from electron microscopy data. There are no free parameters in the biophysical model. We apply this method to IL6, IL15, CXCL9, and CXCL10, inflammatory marker genes in macrophages, before and after immune stimulation, and compare the predictions with contacts measured by conformation capture experiments (4C-seq). We find that within a 500 kilo-basepairs genomic region, polymer mechanics with nucleosomes can explain 71% of close contacts. These results suggest that, while genome contacts on 100kbp-scales are multifactorial, they may be amenable to mechanistic, physical explanation. Our work also highlights the role of nucleosomes, not just at the loci of interest, but between them, and not just the total number of nucleosomes, but their specific placement. The method generalizes to other genes, and can be used to address whether a contact is under active regulation by the cell (e.g., a macrophage during inflammatory stimulation). Importantly, our findings suggest that gene function may have evolved through selective pressures that co-opted contact-mediated regulatory mechanisms reliant largely on polymer mechanics.

Closed-Loop Analysis of Nanocomposite Magnets: Integrating Micromagnetic Simulation and Experimental Testing

This study presents a framework for simulation-experiment closed-loop analysis of nanocomposite magnets. Firstly, hysteresis loops of nanocomposite permanent magnets were calculated using micromagnetic simulations. Then, the experimental preparation was carried out by rapid quenching of the melt and spark plasma sintering (SPS). We analyzed the effect of different sintering temperatures on the physical phase composition and magnetic properties of the samples. Characterization results show that the samples sintered at 600 °C have the highest magnetic energy product. Using transmission electron microscopy data, the polycrystalline model was refined, and further micromagnetic simulations were performed. The close agreement between simulated and experimental data confirms the improved accuracy of our simulation model. This iterative process of experimental characterization and simulation improvement reduces the discrepancy between simulation predictions and actual sample performance. It could facilitate rapid iteration in magnet development and provide valuable insights for optimizing the preparation of nanocomposite permanent magnets.

Automated detection and mapping of crystal tilt using thermal diffuse scattering in transmission electron microscopy

Quantitative interpretation of transmission electron microscopy (TEM) data of crystalline specimens often requires the accurate knowledge of the local crystal orientation. A method is presented which exploits momentum-resolved scanning TEM (STEM) data to determine the local mistilt from a major zone axis. It is based on a geometric analysis of Kikuchi bands within a single diffraction pattern, yielding the center of the Laue circle. Whereas the approach is not limited to convergent illumination, it is here developed using unit-cell averaged diffraction patterns corresponding to high-resolution STEM settings. In simulation studies, an accuracy of approximately 0.1 mrad is found. The method is implemented in automated software and applied to crystallographic tilt and in-plane rotation mapping in two experimental cases. In particular, orientation maps of high-Mn steel and an epitaxially grown La0.7Sr0.3MnO3-SrTiO3 interface are presented. The results confirm the estimates of the simulation study and indicate that tilt mapping can be performed consistently over a wide field of view with diameters well above 100 nm at unit cell real space sampling.

High-resolution 2D solid-state NMR provides insights into nontuberculous mycobacteria

We present a high-resolution magic-angle spinning (MAS) solid-state NMR (ssNMR) study to characterize nontuberculous mycobacteria (NTM). We studied two different NTM strains, Mycobacterium smegmatis, a model, non-pathogenic strain, and Mycobacterium abscessus, an emerging and important human pathogen. Hydrated NTM samples were studied at natural abundance without isotope-labelling, as whole-cells versus cell envelope isolates, and native versus fixed sample preparations. We utilized 1D13C and 2D 1H-13C ssNMR spectra and peak deconvolution to identify NTM cell-wall chemical sites. More than ∼100 distinct 13C signals were identified in the ssNMR spectra. We provide tentative assignments for ∼30 polysaccharides by using well resolved 1H/13C chemical shifts from the 2D INEPT-based 1H-13C ssNMR spectrum. The signals originating from both the flexible and rigid fractions of the whole-cell bacteria samples were selectively analyzed by utilizing either CP or INEPT based 13C ssNMR spectra. CP buildup curves provide insights into the dynamical similarity of the cell-wall components for NTM strains. Signals from peptidoglycan, arabinogalactan and mycolic acid were identified. The majority of the 13C signals were not affected by fixation of the whole cell samples. The isolated cell envelope NMR spectrum overlap with the whole-cell spectrum to a large extent, where the latter has more signals. As an orthogonal way of characterizing these bacteria, electron microscopy (EM) was used to provide spatial information. ssNMR and EM data suggest that the M. abscessus cell-wall is composed of a smaller peptidoglycan layer which is more flexible compared to M. smegmatis, which may be related to its higher pathogenicity. Here in this work, we used high-resolution 2D ssNMR first time to characterize NTM strains and identify chemical sites. These results will aid the development of structure-based approaches to combat NTM infections.

Bifacial perovskite/silicon heterojunction tandem solar cells based on FAPbI3-based perovskite via hybrid evaporation-spin coating

Combining the two technologies of tandem solar cells and bifacial solar cells has a great potential to maximize energy harvesting while minimizing material and surface usage. Mid-bandgap perovskites (1.50–1.60 eV) are important for fulfilling current matching in bifacial perovskite/silicon heterojunction tandem solar cells. Herein, efficient (>20 %) and stable planar FAPbI3-based perovskite (1.54 eV) solar cells have been fabricated via a hybrid evaporation-spin coating process. X-ray diffraction and electron microscopy data reveal the formation of highly crystalline (001) perovskite domains. The fabricated high-quality perovskite films lead to a more homogenized contact potential difference at the film surface and a reduction in non-radiative losses, resulting in a quasi-Fermi-level splitting (half-cell) of 1.16 eV, rendering 120 mV non-radiative losses. Transferring these films into tandem devices atop single-side textured silicon heterojunction bottom cells, we obtain an efficiency of >24 % under AM1.5 G illumination for monofacial devices with an active area of 1.21 cm2. Furthermore, the bifacial devices generate >27 mW cm−2 power output with 15 % rear illumination fraction.