Confocal Scanning Electron Microscopy Research Articles

Comparative Study of High-Cycle Fatigue and Failure Mechanisms in Ultrahigh-Strength CrNiMoWMnV Low-Alloy Steels

This study provides a thorough analysis of the fatigue resistance of two low-alloy ultrahigh-strength steels (UHSSs): Steel A (fully martensitic) and Steel B (martensitic–bainitic). The investigation focused on the fatigue behaviour, damage mechanisms, and failure modes across different microstructures. Fatigue strength was determined through fully reversed tension–compression stress-controlled fatigue tests. Microstructural evolution, fracture surface characteristics, and crack-initiation mechanisms were investigated using laser scanning confocal microscopy and scanning electron microscopy. Microindentation hardness (HIT) tests were conducted to examine the cyclic hardening and softening of the steels. The experimental results revealed that Steel A exhibited superior fatigue resistance compared to Steel B, with fatigue limits of 550 and 500 MPa, respectively. Fracture surface analysis identified non-metallic inclusions (NMIs) comprising the complex MnO-SiO2 as critical sites for crack initiation during cyclic loading in both steels. The HIT results after fatigue indicated significant cyclic softening for Steel A, with HIT values decreasing from 7.7 ± 0.36 to 5.66 ± 0.26 GPa. In contrast, Steel B exhibited slight cyclic hardening, with HIT values increasing from 5.24 ± 0.23 to 5.41 ± 0.31 GPa. Furthermore, the martensitic steel demonstrated superior yield and tensile strengths of 1145 and 1870 MPa, respectively. Analysis of the fatigue behaviour revealed the superior fatigue resistance of martensitic steel. The complex morphology and shape of the NMIs, examined using the 3D microstructure characterisation technique, demonstrated their role as stress concentrators, leading to localised plastic deformation and crack initiation.

Silver induced self-assembly of a rhodanine derived reversible fluorescent chemosensor: Applications in smart-phone color assist app, logic gate, real sample analysis and bio-imaging

An innovative chemosensor, Rhodanine-appended benzaldehyde (RB), was developed and analyzed using spectroscopic methods to detect silver ions (Ag+) in a THF–H2O buffer solution via fluorimetry. The RB probe exhibited low fluorescence due to C-N free rotation and inhibition of electron transfer. However, interaction with Ag+ ions resulted in a noteworthy redshift of approximately 6 nm and increased fluorescence intensity owing to the chelation-enhanced fluorescence (CHEF) effect, which hindered the Intramolecular Charge Transfer (ICT) process. The binding ratio between RB and Ag+ ions was determined to be 2:1 using the job plot method. The association constant (Ka) was calculated to be 4.84 × 105 M−1 and further confirmed through ESI-TOF spectroscopic and DFT analyses. The limit of detection (LOD) and quantification (LOQ) for RB in binding with Ag+ ions were found to be 1.7 × 10−8 M and 5.4 × 10−8 M, respectively. Additionally, the color changes of RB when binding with Ag+ ions were effectively leveraged in an RGB-assisted smartphone color analysis app for precise sample analysis for Ag+ ion detection. Most importantly, the RB probe’s ability to detect silver ions in the E. coli pathogen was successfully demonstrated, providing reassurance about its practical application, using a confocal scanning electron microscope via the green channel.

Effects of Fineness and Morphology of Quartz in Siliceous Limestone on the Calcination Process and Quality of Cement Clinker.

With the increasing depletion of high-quality raw materials, siliceous limestone, sandstone and other hard-to-burn raw materials containing crystalline SiO2 are gradually being used to produce clinker. This study investigates the influence of the quartz content and particle size in siliceous limestone on the calcination process and the resultant quality of cement clinker. Two different siliceous limestones were grinded to different fineness, and calcinated with some other materials. The content of the clinkers was analyzed with the XRD-Rietveld method and the microstructure of the clinkers was observed with laser scanning confocal microscopy (LSCM) and field emission scanning electron microscopy (FESEM). Three key outcomes of this study provide new insights on the use of siliceous limestone in cement production, namely that (i) reducing the fineness values of siliceous limestone from 15% to 0% of residue on a 0.08 mm sieve decreases the quantity of these larger quartz particles, resulting in an increase in C3S content by up to 8% and an increase in 28d compressive strength by up to 4.4 Mpa, which is 62.30 Mpa; (ii) the morphology of quartz-either as chert nodules or single crystals-affects the microstructure of C2S clusters in clinker, finding that chert nodules result in clusters with more intermediate phases, whereas large single crystals lead to denser clusters; (iii) the sufficient fineness values of siliceous limestone SL1 and SL2 are 5% and 7% of residue on a 0.08 mm sieve, respectively, which can produce a clinker with a 28d compressive strength greater than 60 Mpa, indicating that for different kinds of quartz in siliceous limestone, there is an optimum grinding solution that can achieve a balance between clinker quality and energy consumption without having to grind siliceous limestone to very fine grades.

P-035 Catecholamine neuroreceptors are differentially located in functional regions of the human sperm

Abstract Study question How are the expression and distribution of Adrenergic and Dopamine receptors in human sperm cells? Summary answer Using ultra-high-resolution microscopy techniques, we identified that each type of catecholamine receptor is expressed in a different functional region of the human sperm. What is known already Human sperm present complex cell signalling complexes with several neuroreceptors in their membrane. The spermatozoa is a terminal differentiated cell showing specialized regions optimized for physiological processes like motility, acrosome reaction and membrane fusion during fertilization. Although indirect methods have determined the presence of catecholamine receptors in human sperm, there is no direct evidence nor description of the exact localisation of these receptors. Catecholamine receptors are the direct target of medications used to treat very frequent health problems like hypertension (beta blockers), asthma (bronchodilators) and mental health disorders (antipsychotics and antidepressants). Study design, size, duration We design the study by developing new techniques that allow us to use high-resolution microscopes (i.e. Laser Scanning Confocal Microscopy LSCM and Field Emission Scanning Electron Microscopy or FE-SEM) to identify the localisation and distribution of catecholamine receptors. We determined sperm functional regions and quantified the relative amount of the different receptors on each one of those regions to perform a statistical analysis. Participants/materials, setting, methods After informed consent and ethical approval, sperm from young, healthy donors (n = 20) were included in the study. We used the neuroblastoma cell line SH-SY5Y as a positive control. Immunolabelling techniques used specific primary antibodies for each receptor, followed by the gold-conjugated secondary antibodies for FE-SEM. Negative controls were performed by omitting the primary antibody. In FE-SEM images, we quantify the number of gold nanoparticles in the sperm cells and the background. Main results and the role of chance We confirm the differential localisation of the different receptors studied. Dopamine D2 receptors are mainly expressed on the equatorial band of the acrosome, while beta-adrenergic receptors are restricted to the terminal piece of the flagellum. In both cases, the mean number of gold particles showed statistical differences (p < 0,001) between the region of expression and the rest of the regions and the background. Limitations, reasons for caution The present study only shows the presence of the receptors on the sperm plasma membrane. The activity of those receptors should be investigated by developing bioassays based on the use of agonists and/or antagonists. A more reliable genetic overexpression or knockout approach was impossible in human sperm. Wider implications of the findings The presence of receptors on restricted regions of the sperm suggests their participation in critical physiological events, like regulation of sperm motility hyperactivation or acrosome reaction. It may also suggest a possible side effect of beta-blockers or bronchodilators with the male fertility potential that needs to be investigated. Trial registration number not applicable

The Drosophila blood–brain barrier invades the nervous system in a GPCR-dependent manner

The blood–brain barrier (BBB) represents a crucial interface between the circulatory system and the brain. In Drosophila melanogaster, the BBB is composed of perineurial and subperineurial glial cells. The perineurial glial cells are small mitotically active cells forming the outermost layer of the nervous system and are engaged in nutrient uptake. The subperineurial glial cells form occluding septate junctions to prevent paracellular diffusion of macromolecules into the nervous system. To address whether the subperineurial glia just form a simple barrier or whether they establish specific contacts with both the perineurial glial cells and inner central nervous system (CNS) cells, we undertook a detailed morphological analysis. Using genetically encoded markers alongside with high-resolution laser scanning confocal microscopy and transmission electron microscopy, we identified thin cell processes extending into the perineurial layer and into the CNS cortex. Interestingly, long cell processes were observed reaching the glia ensheathing the neuropil of the central brain. GFP reconstitution experiments highlighted multiple regions of membrane contacts between subperineurial and ensheathing glia. Furthermore, we identify the G-protein-coupled receptor (GPCR) Moody as negative regulator of the growth of subperineurial cell processes. Loss of moody triggered a massive overgrowth of subperineurial cell processes into the CNS cortex and, moreover, affected the polarized localization of the xenobiotic transporter Mdr65. Finally, we found that GPCR signaling, but not septate junction formation, is responsible for controlling membrane overgrowth. Our findings support the notion that the Drosophila BBB is able to bridge the communication gap between circulation and synaptic regions of the brain by long cell processes.

Impact of niobium addition and non-metallic inclusions’ characteristics on the microstructure and mechanical properties of low-carbon CrNiMnMoB ultrahigh-strength steel: A comprehensive investigation

The effect of cooling rate and Nb addition on the phase transformation, microstructures, and mechanical properties of thermomechanically controlled hot-rolled low-carbon CrNiMnMoB ultrahigh-strength steel were studied. The aspects impeding Nb's benefits on hardenability, phase transformation, and mechanical properties were investigated. The hot rolling process was simulated, and a continuous cooling transformation diagram was constructed for the studied steels. Microstructures were analysed using laser scanning confocal microscopy and field emission scanning electron microscopy, with the latter also used for in-depth investigations of the non-metallic inclusions. Transmission electron microscopy was employed to investigate the precipitate characteristics. The concentrations of Nb in the solution and precipitates were quantified for the martensitic and granular bainitic structures. The effect of Nb in solution on phase transformation and strengthening is diminished, and the hardness is reduced by Nb precipitation at an early processing stage. Decreasing the cooling rate promotes the formation of granular bainitic structures rather than martensite. After being subjected to hot rolling followed by water quenching and air cooling, the microstructures are autotempered martensite and fully granular bainite, respectively. Various non-metallic inclusions, including Al2O3, MnS, and Al2O3–MnS, MnS·BN, Al2O3·BN and MnS·Al2O3·BN were observed. The number density and area fraction of non-metallic inclusions in the Nb-containing steel and the air-cooled samples are higher than those observed in the Nb-free and water-quenched samples. Adding 0.04 wt% of Nb slightly increased the strength, but the toughness properties dropped, mainly due to the higher number density and area fraction of non-metallic inclusions and primary large precipitates.

The roles of theaflavins in reducing dentin erosion

This study aimed to evaluate the effect of theaflavins [TFs] on the process of dentin erosion and investigation the potential mechanism. For erosion kinetics of the dentin, 7 experimental groups (n = 5) treated with 10% ethanol [EtOH] (negative control) are erosion for 1, 2, 3, 4, 5, 6, and 7 d erosion cycles (4 cycles/d). For the effect of TFs on dentin erosion, 6 experimental groups (n = 5) were treated with 1% epigallocatechin gallate [EGCG], 1% chlorhexidine [CHX], 1%, 2%, 4%, and 8% TFs for the 30 s and then subjected to erosion cycles (4 cycles/d for 7 d). The erosive dentin wear (μm) and surface morphology were evaluated and compared by laser scanning confocal microscope and scanning electron microscopy. The matrix metalloproteinase inhibition effects of TFs were investigated using in situ zymography and molecular docking. TFs-treated collagen was investigated by ultimate microtensile strength, Fourier-transform infrared spectroscopy, and molecular docking. Data were analyzed by ANOVA, Tukey’s test (P < 0.05). The TFs-treated groups (7.56 ± 0.39, 5.29 ± 0.61, 3.28 ± 0.33, and 2.62 ± 0.99 μm for 1%, 2%, 4%, and 8% TFs) had significantly lower erosive dentin wear than the negative control group (11.23 ± 0.82 μm), and the effect was concentration-dependent at low concentrations (P < 0.05). TFs inhibit matrix metalloproteinase [MMP]. Moreover, TFs crosslink dentin collagen and cause hydrophilic changes in dentin collagen. TFs preserve organic matrix within the demineralized dentin by inhibiting MMP activity and simultaneously improving collagen’s resistance to enzymes, both of which contribute to preventing or slowing down the progression of dentin erosion.

Glyoxal-induced disruption of tumor cell progression in breast cancer.

Breast cancer is the most common malignant tumor in women and remains a major global challenge, with ~1.4 million cases per year, worldwide. Numerous studies have shown that changes in cell metabolism are associated with the regulation of tumor progression. In the present study, the anti-cancer properties of glyoxal (GO), which is the smallest dialdehyde formed in the oxidation-reduction reaction and involved in electron transfer and energy metabolism, in breast cancer was investigated. The biological functions and molecular mechanisms of GO were investigated in breast cancer cell lines using MTT and crystal violet assays, flow cytometry, western blot analysis, 3D laser scanning confocal microscopy and transmission electron microscopy. The results showed that GO strongly inhibited cell proliferation, promoted cell apoptosis and cell cycle G2/M arrest, induced the disappearance of cellular microvilli, and enlarged mitochondria. In addition, the protein expression level of AKT, mTOR and p70-S6K decreased in the AKT-mTOR pathway, accompanied by an increase in p-ERK and p-MEK in the MAPK pathway. The results from the present study indicate that GO suppressed breast cancer progression via the MAPK and AKT-mTOR pathways. Taken together, these results provide the basis for a potential therapeutic strategy for breast cancer.

Plasma from patients with pulmonary embolism show aggregates that reduce after anticoagulation

BackgroundMicroclots, a term also used for amyloid fibrin(ogen) particles and henceforth named aggregates, have recently been reported in the plasma of patients with COVID-19 and long COVID. These aggregates have been implicated in the thrombotic complications of these diseases.MethodsPlasma samples from 35 patients with acute pulmonary embolism were collected and analysed by laser scanning confocal microscopy and scanning electron microscopy before and after clotting.ResultsHere we confirm the presence of aggregates and show that they also occur in the plasma of patients with pulmonary embolism, both before and after clotting. Aggregates vary in size and consist of fibrin and platelets. We show that treatment with low-molecular weight heparin reduces aggregates in the samples of patients with pulmonary embolism. Double centrifugation of plasma does not eliminate the aggregates.ConclusionsThese data corroborate the existence of microclots or aggregates in diseases associated with venous thromboembolism. Important questions are raised regarding their pathophysiological relevance and further studies are warranted to investigate whether they represent cause or consequence of clinical thrombosis.

OBSERVAÇÃO E ANÁLISE DE IMAGEM BASEADA EM SENSORES VISUAIS DAS LESÕES MUSCULARES EM ATLETAS

ABSTRACT Introduction: Athletes and fitness enthusiasts often suffer muscle injuries during their training. These injuries can worsen when not treated properly, generating an accumulation of severe tissue damage, preventing optimal physical performance, and impacting low immunity. Despite a large number of researches on muscle injuries, its vast majority is limited to the pathological perspective, and there are few studies related to the specific impact of the body sport muscle injury index. Objective: Analyze the body-specific indicators of sports injury to prevent further damage to its practitioners. Methods: Laser scanning confocal electron microscopy is the main observation tool in studying muscle injury in athletes. In further research, an experimental animal model was established. The test samples were 40 male rats over 12 weeks old, randomly divided into four groups, treadmill exercise, swimming at 8% of the weight, and other sports training items. Results: Through the comparative experiment of three indicators, it is found that muscle damage has a widespread impact on the whole body, particularly on blood serum indicators. The period of one hour after injury is considered to have the most impact. However, the symptoms subside after 24 hours. Conclusion: As the main observation tool in this experiment, the microscope showed its good prospect of application in the field of biomedicine. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Fabrication of 3D melt electrowritting multiphasic scaffold with bioactive and osteoconductivite functionalities for periodontal regeneration

This work aimed to design a multifunctional biphasic 3D scaffold for periodontal tissue regeneration. A 3D fibrous scaffold made from medical-grade poly (ε-caprolactone) (PCL) with high porosity (>90%) and well-oriented fibres was fabricated by a custom design melt electrowriting (MEW) device. A biomimetic process was employed to form a bioactive calcium phosphate (CaP) layer with nanostructure (nanoflakes-like) morphology onto the 3D MEW fibrous surface to stimulate rapid bone formation. Primary human osteoblasts (hOBs) were seeded within the coated 3D fibrous scaffolds for 28 days to acquire the bone compartment of the tissue-engineered construct (TEC). The biphasic construct was obtained by placing an established in vitro periodontal ligament (PDL) cell sheet onto the surface of the bone compartment. Subsequently, a decellularized multiphasic TEC by exploiting a lyophilization approach was obtained. Laser scanning confocal microscopy and scanning electron microscopy confirmed the retention of a functional extracellular matrix within the PDL and bone compartments following scaffold decellularization and lyophilization processes. These findings suggest that lyophilized decellularized biphasic 3D constructs with high porosity constitute a viable ‘off the shelf’ strategy for developing an extracellular matrix-based product to facilitate periodontal regeneration.

Garlic essential oil in water nanoemulsion prepared by high-power ultrasound: Properties, stability and its antibacterial mechanism against MRSA isolated from pork

Food-borne methicillin-resistance Staphylococcus aureus (MRSA) has caused significant health threats and economic loss in livestock and poultry products. Garlic essential oil (GEO) is an effective antibacterial agent but presents strong instability and hydrophobicity. In this study, GEO in water nanoemulsion (GEON) with good stability was produced by emulsification technique of high-power ultrasound. Its antibacterial activity and underlying mechanism against MRSA isolated from retailed pork were investigated. Results showed that ultrasonic treatment significantly reduced the particle size of GENO from 820.3 to 215.0 nm as time increased from 0 to 10 min. Comparatively, GEON of 10 min ultrasound was more stable than other GEONs (0, 1, 5 min) during 30 d storage. It also displayed good thermal stability and relatively good ion stability (NaCl, MgCl2, and glucose). Antibacterial analysis showed that GEON (10 min) exhibited the best anti-MRSA activity among all GEONs, and the minimum inhibitory concentration of GEO in this nanoemulsion was 0.125 % (1.25 mg/mL). Treatment of GEON (10 min) significantly suppressed the cell proliferation of MRSA, which was mainly achieved by damaging the cell membrane as evidenced by membrane depolarization and considerable leakage of intracellular nucleic acids and protein. Laser scanning confocal microscope and scanning electron microscopy showed that treatment of GEON (10 min) significantly altered the membrane integrity and severely damaged the cellular membrane and structure. The present work illustrated that GEON produced by ultrasonic emulsification is a promising alternative to inhibit the contamination and spread of MRSA in livestock and poultry products.

Investigation on dislocation and deflection morphology of PVT-grown on-axis 4H-SiC crystals

The morphologies of dislocation etch pits and dislocation deflections of on-axis 4H-SiC substrate etched by molten KOH were observed with the help of a microscope. Based on experimental observation and etch mechanism, a method for the identification of threading edge dislocations, threading screw dislocations (TSDs) and threading mixed dislocations was proposed. The details about the inner micro-structure of threading edge dislocations and TSDs were observed by laser scanning confocal microscope and scanning electron microscopy. The morphologies and the cross-sectional views of the basal plane dislocation formed by threading edge dislocation were observed and two models were formed to explain it.

Bio-responsive composite liposomes against Campylobacter jejuni in vitro and its application in chicken preservation

The infection of Campylobacter jejuni (C. jejuni) in food can cause huge economic and health costs, and liposomes based on biological switch is a promising antibacterial strategy. In this study, a bio-responsive composite liposome was designed with silk fibroin and L-fucose (FLPs) based on the chemotaxis and protease of C. jejuni, and Litsea cubeba essential oil as antibacterial agent. The oil encapsulation and protein mosaic rates of the composite liposome were 70.6 ± 0.5% and 47.9 ± 1.0%, respectively. The in vitro release experiment verified that the release rates of essential oil from the liposome exceeded 95% at 5 days. Furthermore, FLPs possessed excellent antibacterial activity, the inhibition zone was 23.5 mm and 20% (v/v) of the composite liposomes could inactivate 99% C. jejuni. Moreover, laser scanning confocal microscopy and scanning electron microscopy images confirmed the antimicrobial activity of FLPs was better than that of other liposomes, and it could attach to bacteria well. Sprayed liposomes revealed sustained ability of retarding bacterial reproduction within 5 days with the refrigerated chicken meat inoculated with C. jejuni, and had no impact on the color and texture of the food. Hence, the bio-responsive composite liposome has a promising application in inhibiting C. jejuni growth in food. Industrial relevanceIn this study, the composite liposome with high encapsulation efficiency shows significant and sustained antibacterial activity, and has no negative effects on the color and texture of chicken meat. The findings of this study will facilitate the development and application of liposomes as active antimicrobial packaging in food industry.

Wear behavior of (Mo–Nb–Ta–V–W)C high‐entropy carbide

AbstractWear characteristics of an (Mo–Nb–Ta–V–W)C high‐entropy carbide were investigated using ball‐on‐flat technique. The experimental material with a high relative density of 99.0%, single phase, average grain diameter of 10.7 μm, and nanohardness of grains 28.6 GPa was prepared by ball‐milling and two‐step field‐assisted sintering. The tribological test was realized during dry sliding in air with the SiC ball as tribological partner at applied loads 5, 25, and 50 N. The microstructure, deformation, and damage characteristics were studied using scanning electron microscopy and confocal electron microscopy. The friction coefficient values during the test with 5 and 25 N were very similar and stable, with a value of approximately .4, whereas during the test with 50 N, it decreased from the value of .48–.42. The specific wear rate increased with increasing load from 3.71 × 10–7 mm3/N m at 5 N to 2.59 × 10–6 mm3/N m at 50 N. The dominant wear mechanism was mechanical wear with intensive grains pullout, fracture, and powder formation, without visible tribochemical reactions and tribo‐layer formation. The wear rate decreased due to the created rolling contacts among the tribopartners thanks to the hard and spherical nanopowders present.

The forming of microgroove in copper foil on multiple laser-induced cavitation impacts

A method to fabricate microgrooves using laser-induced cavitation shock forming is proposed. In this paper, the deforming behavior of copper foil is investigated using the experimental approach of multiple impacts of laser-induced cavitation bubbles. The microgroove structure was characterized by laser scanning confocal microscopy and scanning electron microscopy. As the number of impacts increase, the forming depth gradually decreases due to work hardening and loss of impact pressure. However, the surface roughness at the bottom of the microgroove increases and is covered with an oxide layer. The thickness and hardness distributions of the cross-section of the formed micro-groove are also studied. The results demonstrate that the maximum thickness thinning occurs at the bottom of the micro-groove, and the thickness reduces from 50 μm to 14 μm. The hardness of the material rises to varying degrees along the cross-section, and as the number of impacts grows from one to four, the hardness value rises from 1079 MPa to 2420 MPa.

In vitro digestion of whole chia seeds (Salvia hispanica L.): Nutrient bioaccessibility, structural and functional changes

AbstractDietary chia seed (Salvia hispanica L.) has significant health‐related benefits due to its high nutrient contents. However, few studies reported the fate of whole seeds in the gastrointestinal tract. Herein, we explored the digestive characteristics in terms of hydrolysis of nutrients, structural and functional properties with a static in vitro digestion method. After gastrointestinal digestion, the digestibility of lipid and protein was 0.46% and 11.38%, respectively. The release rates of tryptophan, tyrosine and lysine were greater than 20%, whereas the glutamic acid and aspartic acid were less than 5%. The microscopic results (optical microscopy (OM), laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM)) demonstrated that the seeds remained intact, and the mucilage adhered tightly to the seed coat during digestion. The water holding capacity and oil holding capacity of seeds accounted for 6.37 and 3.28 g/g after intestinal digestion, which were significantly lower than gastric digestion endpoints (P &lt; 0.05). And there were no significant differences in Fourier transform infrared spectroscopy of G‐Mucilage and I‐Mucilage. In general, preprocessing before being consumed is necessary for chia seeds to take full advantage of rich polyunsaturated fatty acids and proteins.

Bacterial Biofilm Formation on Nano-Copper Added PLA Suited for 3D Printed Face Masks.

The COVID-19 Pandemic leads to an increased worldwide demand for personal protection equipment in the medical field, such as face masks. New approaches to satisfy this demand have been developed, and one example is the use of 3D printing face masks. The reusable 3D printed mask may also have a positive effect on the environment due to decreased littering. However, the microbial load on the 3D printed objects is often disregarded. Here we analyze the biofilm formation of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli on suspected antimicrobial Plactive™ PLA 3D printing filaments and non-antimicrobial Giantarm™ PLA. To characterize the biofilm-forming potential scanning electron microscopy (SEM), Confocal scanning electron microscopy (CLSM) and colony-forming unit assays (CFU) were performed. Attached cells could be observed on all tested 3D printing materials. Gram-negative strains P. aeruginosa and E. coli reveal a strong uniform growth independent of the tested 3D filament (for P. aeruginosa even with stressed induced growth reaction by Plactive™). Only Gram-positive S. aureus shows strong growth reduction on Plactive™. These results suggest that the postulated antimicrobial Plactive™ PLA does not affect Gram-negative bacteria species. These results indicate that reusable masks, while better for our environment, may pose another health risk.

Tin and zinc microparticle impacts above the critical adhesion velocity

In cold spray, the critical adhesion velocity, or the point at which microparticles start to adhere to the substrate upon impact, defines the lower bound of the velocity window over which deposition can occur. Less information is available on the upper bound of this deposition window, which has previously been connected to both melting and hydrodynamic penetration processes that can lead to erosion. In this study, we examine impacts of tin microparticles on a tin substrate and zinc microparticles on a zinc substrate across a range of velocities above the critical adhesion velocity. We observe a variety of phenomena that occur as impact velocity is increased, including jetting, melting, fragmentation, and hydrodynamic penetration. Using laser scanning confocal microscopy and scanning electron microscopy, we quantify the net amount of material deposited at each impact site for each material. We use these measurements to understand the circumstances under which an erosive condition is met at high velocities, in which net deposition of microparticle material to the substrate no longer occurs. • Impact-induced melting occurs in both tin and zinc single microparticle impacts. • Confocal microscopy can be used to quantify erosion onset at high velocities. • Erosion in cold spray is caused by melting, penetration, and/or fragmentation. • Jetting, fragmentation, melting, & penetration occur at material-specific speeds.

Preparation, urease inhibition mechanisms, and anti-Helicobacter pylori activities of hesperetin-7-rhamnoglucoside.

This work investigated the effects of the bioflavonoid hesperetin-7-rhamnoglucoside isolated from Citrus uranium fruit peel on Helicobacter pylori (H. pylori). Separation and purity, crystalline state, and urease inhibition assays were carried out. Then, molecular docking and molecular dynamics (MD) simulations were conducted with urease as the target protein. Hesp was isolated from citrus peel with a purity of 95.14 µg mg-1 of dry raw material. X-ray diffraction analysis, hydrogen-1 nuclear magnetic resonance, Fourier transform infrared spectroscopy, and differential scanning calorimetry revealed that pure Hesp had the same crystallinity rating as the Hesp standard. The kinetic inhibition study demonstrated that Hesp inhibited H. pylori urease in a competitive and concentration-dependent manner with jack bean urease. In addition, bioimaging studies with laser scanning confocal microscopy and scanning electron microscopy illustrated that Hesp interacted with bacterial cells and induced membrane disruption by creating holes in the outer membranes of the bacterial cells, resulting in the leakage of amino acids. Importantly, molecular docking and 20 ns MD simulations revealed that Hesp inhibited the target protein through slow-binding inhibition and hydrogen bond interactions with active site residues, namely, Gly11 (O⋯H distance=2.2 Å), Gly13 (O⋯H distance=2.4 Å), Ser12 (O⋯H distance=3.3 Å), Lys14 (O⋯H distance=3.3 Å), and Arg179 (O⋯H distance=2.7 Å). This work presents novel anti- H. pylori agents from natural sources.