Confocal Scanning Microscopy Research Articles

Trans, Trans-Farnesol Enhances the Anti-Bacterial and Anti-Biofilm Effect of Arachidonic Acid on the Cariogenic Bacteria Streptococcus mutans and Streptococcus sobrinus.

Streptococcus mutans and Streptococcus sobrinus are Gram-positive bacteria involved in the development of dental caries, as they are able to form biofilms on tooth enamel, ferment sugars into acids, and survive under acidic conditions. This ultimately leads to a local lowering of the pH value on the tooth surface, which causes enamel cavities. One measure to reduce caries is to limit the growth of cariogenic bacteria by using two anti-bacterial agents with different mechanisms of action. The hypothesis of this study was that the anti-bacterial activity of ω-6 polyunsaturated arachidonic acid (AA) against S. mutans and S. sobrinus can be enhanced by the sesquiterpene alcohol trans, trans-farnesol (t,t-farnesol). The anti-bacterial activity of single and combined treatment was determined by the checkerboard assay. Bacterial viability was assessed by live/dead SYTO 9/propidium iodide (PI) staining on flow cytometry. Anti-biofilm activity was determined by MTT metabolic assay, crystal violet staining of biofilm biomass, SYTO 9/PI staining by spinning disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). t,t-Farnesol lowered the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of AA at sub-MICs. AA reduced the metabolic activity of preformed mature biofilms, while t,t-farnesol had no significant effect. The enhanced anti-bacterial effect of the combined t,t-farnesol/AA treatment was further evidenced by increased PI uptake, indicating membrane perforation. The enhanced anti-biofilm effect was further verified by SDCM and HR-SEM. Gene expression studies showed reduced expression of some biofilm-related genes. Altogether, our study suggests a potential use of the two naturally occurring compounds arachidonic acid and t,t-farnesol for preventing biofilm formation by the cariogenic bacteria S. mutans and S. sobrinus. These findings have implications for caries prevention.

Potential probiotic Lactiplantibacillus plantarum strains alleviate TNF-α by regulating ADAM17 protein and ameliorate gut integrity through tight junction protein expression in in vitro model

BackgroundLactiplantibacillus species are extensively studied for their ability to regulate host immune responses and functional therapeutic potentials. Nevertheless, there is a lack of understanding on the mechanisms of interactions with the hosts during immunoregulatory activities.MethodsTwo Lactiplantibacillus plantarum strains MKMB01 and MKMB02 were tested for probiotic potential following Indian Council of Medical Research (ICMR) guidelines. Human colorectal adenocarcinoma cells such as HT-29, caco-2, and human monocytic cell THP-1 were also used to study the potential of MKMB01 and MKMB02 in regulating the host immune response when challenged with enteric pathogen Salmonella enterica typhimurium. Cells were pre-treated with MKMB01 and MKMB02 for 4 h and then stimulated with Salmonella. qRT-PCR and ELISA were used to analyze the genes and protein expression. Confocal microscopy and field emission scanning electron microscopy (FESEM) were used to visualize the effects. An Agilent Seahorse XF analyzer was used to determine real-time mitochondrial functioning.ResultsBoth probiotic strains could defend against Salmonella by maintaining gut integrity via expressing tight junction proteins (TJPs), MUC-2, and toll-like receptors (TLRs) negative regulators such as single Ig IL-1-related receptor (SIGIRR), toll-interacting protein (Tollip), interleukin-1 receptor-associated kinase (IRAK)-M, A20, and anti-inflammatory transforming growth factor-β and interleukin-10. Both strains also downregulated the expression of pro-inflammatory cytokines/chemokines interleukin-1β, monocyte chemoattractant protein (MCP)-1, tumor necrosis factor-alpha (TNF-α), interleukin 6, and nitric oxide (NO). Moreover, TNF-α sheddase protein, a disintegrin and metalloproteinase domain 17 (ADAM17), and its regulator iRhom2 were downregulated by both strains. Moreover, the bacteria also ameliorated Salmonella-induced mitochondrial dysfunction by restoring bioenergetic profiles, such as non-mitochondrial respiration, spare respiratory capacity (SRC), basal respiration, adenosine triphosphate (ATP) production, and maximal respiration.ConclusionsMKMB01 and MKMB02 can reduce pathogen-induced gut-associated disorders and therefore should be further explored for their probiotic potential.

Skin Cancer Image Classification Using Artificial Intelligence Strategies: A Systematic Review

The increasing incidence of and resulting deaths associated with malignant skin tumors are a public health problem that can be minimized if detection strategies are improved. Currently, diagnosis is heavily based on physicians’ judgment and experience, which can occasionally lead to the worsening of the lesion or needless biopsies. Several non-invasive imaging modalities, e.g., confocal scanning laser microscopy or multiphoton laser scanning microscopy, have been explored for skin cancer assessment, which have been aligned with different artificial intelligence (AI) strategies to assist in the diagnostic task, based on several image features, thus making the process more reliable and faster. This systematic review concerns the implementation of AI methods for skin tumor classification with different imaging modalities, following the PRISMA guidelines. In total, 206 records were retrieved and qualitatively analyzed. Diagnostic potential was found for several techniques, particularly for dermoscopy images, with strategies yielding classification results close to perfection. Learning approaches based on support vector machines and artificial neural networks seem to be preferred, with a recent focus on convolutional neural networks. Still, detailed descriptions of training/testing conditions are lacking in some reports, hampering reproduction. The use of AI methods in skin cancer diagnosis is an expanding field, with future work aiming to construct optimal learning approaches and strategies. Ultimately, early detection could be optimized, improving patient outcomes, even in areas where healthcare is scarce.

Damaging effect of fine grinding treatment on the microstructure of polyurea elastomer modifier used in asphalt binder

The excellent elasticity and strength of polyurea elastomer could provide good potential in asphalt modification. In this paper, PUA materials were prepared by spraying and crushing technology. Using liquid nitrogen, PUA was ground into powders of different particle sizes. The size composition and characteristics of PUA powder were analyzed using laser particle size analyzer. The functional microstructures were identified through laser confocal scanning microscopy. The damaging effect of grinding on functional microstructures was investigated. The impact of PUA on the rheological property of asphalt was determined. The results showed that the size distribution of PUA powders presents the normal distribution characteristic, and the size distribution of 0.3 mm, 0.15 mm, and 0.075 mm PUA powders have intersection. The spherical microstructure distributed independently in PUA particle and some spherical microstructure distributed in the triangular shape. The width/length ratio of characteristic microstructure in 0.15 mm and 0.075 mm PUA powder were increased, which supposed that the spherical microstructure had been damaged by grinding effect. PUA could reduce the cumulative deformation of asphalt when suffering from repeated loads.

Shearmetry of Fluids with Tunable Rheology by Polarized Luminescence of Rare Earth-Doped Nanorods.

Shear stress plays a critical role in regulating physiological processes within microcirculatory systems. While particle imaging velocimetry is a standard technique for quantifying shear flow, uncertainty near boundaries and low resolution remain severe restrictions. Additionally, shear stress determination is particularly challenging in biofluids due to their significant non-Newtonian behaviors. The present study develops a shearmetry technique in physiological settings using a biomimetic fluid containing rare earth-doped luminescent nanorods acting in two roles. First, they are used as colloidal additives adjusting rheological properties in physiological media. Their anisotropic morphology and interparticle interaction synergistically induce a non-Newtonian shear-thinning effect emulating real biofluids. Second, they can probe shear stress due to the shear-induced alignment. The polarized luminescence of the nanorods allows for quantifying their orientational order parameter and thus correlated shear stress. Using scanning confocal microscopy, we demonstrate the tomographic mapping of the shear stress distribution in microfluidics. High shear stress is evident near the constriction and the cellular periphery, in which non-Newtonian effects can have a significant impact. This emerging shearmetry technique is promising for implementation in physiological and rheological environments of biofluids.

Phase behavior and interaction of strong polyelectrolyte dextran sulfate and whey protein isolation: Effects of pH, protein/polysaccharide ratio, and salt addition

The strong polyelectrolyte dextran sulfate (DS) is an anionic polysaccharide with a high negative charge, characterized by high stability and pH independence. DS and whey protein isolate (WPI) were selected to study the specific effects of highly negatively charged polysaccharides on the phase behavior and interaction of WPI/DS complexes (1 % w/v) under varying external conditions (pH, WPI:DS ratio, and salt addition). The phase diagrams, zeta potential, and laser confocal scanning microscopy measurements indicated that the WPI/DS complexes did not dissociate even at pH 1 due to the pH independence of DS. The exclusion volume effect of DS promoted WPI self-aggregation at high salt concentrations, which inhibited acidification-induced dissociation. Isothermal titration calorimetry indicated that the WPI/DS interaction is a spontaneous exothermic reaction driven by both enthalpy and entropy changes due to electrostatic interactions. This study provides valuable information on the interactions between highly negatively charged polysaccharides and proteins.

Phase-only mask for superoscillatory enhanced resolution in confocal microscopy

In this work, we present a simple phase mask that generates a superoscillatory spot suitable for confocal scanning microscopy enabling lateral sub-diffraction resolution. When considering linearly polarized light, the mask enhances the resolving power along the axis perpendicular to the polarization direction. The symmetry of the enhancement is recovered if the mask is combined with radial polarization.

Taxonomic insights into medicinal plants pollen, using advanced microscopy techniques, from the Western Ghats, India

Pollen morphological study on 18 medicinal plants from the Western Ghats (India) was carried out using light microscopy (LM), confocal laser scanning microscopy (CLSM) and field emission scanning electron microscopy (FESEM) techniques. The principal aim was to obtain high-resolution three-dimensional images and ultra-structure of the pollen grains of the studied taxa. The palyno-morphological characters, such as polar axis, equatorial diameter, P/E ratio, pollen shape, aperture type and number, exine thickness and surface ornamentation will be useful in the identification and taxonomic classification of the studied medicinal plants. Statistical analysis reveals grouping of the taxa in three different clusters and also isolated presence of taxa on the principal component analysis (PCA) biplot, irrespective of their families, showing similarities and/or variations among the studied taxa, belonging to the same and/or different families. The present study has taxonomic significance, providing high taxonomic resolution (identification of the taxa up to species level), and further aid in the identification and delimitation of the 18 studied plants.

Microstructure and Hardness Properties of Additively Manufactured AISI 316L Welded by Tungsten Inert Gas and Laser Welding Techniques.

In this study, 316L austenitic stainless-steel (ASS) plates fabricated using an additive manufacturing (AM) process were joined using tungsten inert gas (TIG) and laser welding techniques. The 316L ASS plates were manufactured using a laser powder bed fusion (LPBF) technique, with building orientations (BOs) of 0° and 90°, designated as BO-0 and BO-90, respectively. The study examined the relationship between indentation resistance and microstructure evolution within the fusion zone (FZ) of the welded joints considering the effects of different BOs. Microstructural analysis of the weldments was conducted using optical and laser confocal scanning microscopes, while hardness measurements were obtained using a micro-indentation hardness (HIT) technique via the Berkovich approach. The welded joints produced with the TIG technique exhibited FZs with a greater width than those created by laser welding. The microstructure of the FZs in TIG-welded joints was characterized by dendritic austenite and 1-4 wt.% δ-ferrite phases, while the corresponding microstructure in laser-welded joints consisted of a single austenite phase with cellular structures. Additionally, the grain size values of FZs produced using the laser welding technique were lower than those produced using the TIG technique. Therefore, TIG-welded joints showcased hardness values lower than those welded by laser welding. Furthermore, welded joints with the BO-90 orientation displayed the greatest cooling rates following welding processing, leading to FZs with hardness values greater than BO-0. For instance, the FZs of TIG-welded joints with BO-0 and BO-90 had HIT values of 1.75 ± 0.22 and 2.1 ± 0.09 GPa, whereas the corresponding FZs produced by laser welding had values of 1.9 ± 0.16 and 2.35 ± 0.11 GPa, respectively. The results have practical implications for the design and production of high-performance welded components, providing insights that can be applied to improve the efficiency and quality of additive manufacturing and welding processes.

Confocal structured illumination microscopy for improving the signal-to-noise ratio and depth of fluorescent optical section imaging

Light scattering from the sample is an unavoidable problem in fluorescence imaging. Compared with laser scanning confocal scanning microscopy, although optical-sectioning structured illumination microscopy (OS-SIM) has the advantages of fast imaging speed and low phototoxicity, it faces the challenge of removing the scattering fluorescent noise particularly when imaging thick and densely labeled sampling. To improve the imaging performance of OS-SIM, we introduce the concept of confocal imaging to OS-SIM and propose confocal structured illumination microscopy (CSIM). CSIM exploits the principle of dual imaging to reconstruct a dual image from each camera pixel. The scattered fluorescent noise and the unscattered fluorescent signal recorded by the camera pixel are separated in the reconstructed dual image. By extracting the unscattered fluorescent signal from each dual image based on the conjugate relationship between the camera and the spatial light modulator, we can eliminate the scattered fluorescent noise and reconstruct a confocal image. We have built the theoretical framework of CSIM. Experimental results of fluorescent optical-sectioning demonstrate that CSIM achieves a superior performance in eliminating scattered fluorescent noise and in extending imaging depth compared with existing OS-SIM. CSIM is expected to broaden the application range of OS-SIM.

A natural protein-lipid co-assembly as efficient Pickering emulsifier from egg yolk sphere microgel prepared via high-pressure homogenization

Egg yolk sphere is a kind of natural colloidal histological structure formed by the co-assembly of a large number of proteins and lipids, which has the dual functions of hydrophilic and lipophilic for application in emulsion. In this study, egg yolk sphere microgels (EYSMs) were prepared by high pressure homogenization (HPH) technique at various pressures (0–90 MPa) and used as Pickering emulsifiers for emulsification to obtain oil-in-water emulsions with an oil-water ratio of 11:9. The microscopic morphology, structure, and physicochemical properties of EYSMs were analyzed. The results showed that EYSMs obtained at 60 MPa (60-EYSMs) exhibited superior emulsifying properties with an emulsifying activity index (EAI) of 2.8 m2/g and an emulsifying stability index (ESI) of 356.6 min, resulting in enhanced storage stability of the emulsion for 30 d. The HPH treatment decreased the lipid content in EYSMs while creating a more homogeneous protein-lipid arrangement, which provided EYSMs with balanced hydrophilic and hydrophobic sites to improve emulsifying properties. Furthermore, the free sulfhydryl groups and hydrophobic moieties exposed by HPH promoted -S-S- formation on the EYSMs surface, promoting the increase in surface hydrophobicity and emulsifying ability. The confocal laser scanning microscopy (CLSM) and cryogenic scanning electron microscopy (cryo-SEM) revealed that the EYSMs adsorbed at oil-water interface and formed an intercross-linked spatial three-dimensional network structure, which worked as a physical barrier to the stable emulsion formation. This study introduces a novel research concept and delves into the emulsification mechanism of protein-lipid composite particles, offering a fresh insight for the development and utilization of emulsifiers.

Research on the evolution law of aggregate micro-texture during long-term wearing of asphalt pavement

The micro-texture of aggregates plays a very important role in anti-skid performance of asphalt pavement. Three kinds of aggregates, limestone, basalt and sandstone, were used to prepare asphalt mixture to study the evolution law of micro-texture of aggregates under long-term wear. One Third Scaled Model Mobile Load Simulator (MMLS) was used to conduct wear tests on asphalt mixtures under two working conditions: drying and water immersion. Laser confocal scanning microscopy (LCSM) was used to test and analyze the micro-texture evolution of the original aggregate, mixed aggregate, and accelerated loaded aggregate surfaces. The mechanism of texture evolution was analyzed based on the mineral composition, Vickers hardness, and micro-structure of the aggregate. The results show that wear can lead to varying degrees of polishing of the aggregate micro-texture, with limestone>basalt>sandstone, and the drying condition is more severe than the water immersion condition. The wear degree of the texture is closely related to the mineral composition and hardness of the aggregate. The more complex the mineral composition, the greater the hardness and hardness dispersion, the less likely the texture will be polished. The micro-texture indexes Ra and Rq have the highest correlation with anti-skid performance, and the relationship between them is obtained by fitting. Scanning electron microscopy (SEM) shows that the fine particles in sandstone are easy to fall off, which is conducive to the regeneration of texture, and is also the internal reason for its best anti-skid durability.

Effect of building orientation on weld characteristics of additively manufactured 316L stainless steel: Microstructure and mechanical properties

In this study, the influence of building orientation of additively manufactured 316L stainless steel (SS) welded joints was investigated. Laser powder bed fusion (LPBF) technique was employed to print 316L SS plates in three different building orientations (BO): horizontal, inclined at 45°, and vertical directions. Subsequently, the welding processing of the printed 316L plates were conducted in various directions to the building orientations, i.e., the weld directions were perpendicular to the built layer (W90D) in horizontal specimens, parallel (W0D) in the vertical specimens, and oriented with 45° (W45D) to the inclined layers. The microstructure features were characterized using electron backscattered diffraction (EBSD) and laser confocal scanning microscopy (LCSM). The mechanical properties were evaluated through tension tests and hardness measurements. Fracture mode after tensile testing was examined by scanning electron imaging.The microstructural analysis revealed that the fusion zone (FZ) consisted of a predominantly austenitic matrix with the presence of 1–4% δ-ferrite. The FZ of the W0D joints exhibited fine grain structure and lowest dendrites arm spacing as compared to W90D and W45D. The hardness measurements in the FZ of W90D and W45D are 143 ± 5 and 155 ± 6 HV, respectively. These values were lower than the hardness of W0D joints, which measured 180 ± 7 HV. During tensile testing, the W90D and W45D joints were observed to fracture at the FZ, recording ultimate tensile strength (UTS) of 531 and 548 MPa, respectively. In contrast, the W0D joints fractured outside the FZ, displaying a lower UTS of 492 MPa. Furthermore, the welded joints displayed a ductile fracture mode, while W0D joints showed a very fine dimple structure, indicative of a different failure mechanism.

Analysis of Amyloid Fibrillation of Two Family 1 Glycoside Hydrolases.

The formation and analysis of amyloid fibers by two β-glucosidases, BglA and BglB, belonging to the GH1 enzyme family, are reported. Both proteins have the (β/α)8 TIM-barrel fold, which is characteristic of this family and is also the most common protein structure. BglA is an octamer, whereas BglB is a monomer. Amyloid fibrillation using pH and temperature as perturbing agents was investigated using fluorescence spectroscopy as a preliminary approach and corroborated using wide-field optical microscopy, confocal microscopy, and field-emission scanning electron microscopy. These analyses showed that both enzymes fibrillate at a wide range of acidic and alkaline conditions and at several temperature conditions, particularly at acidic pH (3-4) and at temperatures between 45 and 65 °C. Circular dichroism spectroscopy corroborated the transition from an α-helix to a β-sheet secondary structure of both proteins in conditions where fibrillation was observed. Overall, our results suggest that fibrillation is a rather common phenomenon caused by protein misfolding, driven by a transition from an α-helix to a β-sheet secondary structure, that many proteins can undergo if subjected to conditions that disturb their native conformation.

Observation of Initial Interfacial Reaction between High Aluminum Molten Steel and CaO–Al2O3 Inclusion at 1873 K Using Laser Confocal Scanning Microscopy and Micro‐Computerized Tomography

Observation of Initial Interfacial Reaction between High Aluminum Molten Steel and CaO–Al₂O₃ Inclusion at 1873 K Using Laser Confocal Scanning Microscopy and Micro‐Computerized Tomography

Integrated system for temperature-controlled fast protein liquid chromatography. IV. Continuous ‘one-column’ ‘low-salt’ hydrophobic interaction chromatography

Systematic development of a temperature-controlled isocratic process for one-column low-salt hydrophobic interaction chromatography (HIC) of proteins employing a travelling cooling zone reactor (TCZR) system, is described. Batch binding and confocal scanning microscopy were employed to define process conditions for temperature-reversible binding of bovine serum albumin (BSA) which were validated in pulse-response temperature switching HIC experiments, before transferring to TCZR-HIC. A thin-walled stainless-steel column mounted with a movable assembly of copper blocks and Peltier elements (travelling cooling zone, TCZ) was used for TCZR-HIC. In pulse-response TCZR-HIC, 12 TCZ movements along the column desorbed 86.3% of the applied BSA monomers in 95.3% purity depleted >6-fold in 2–4 mers and nearly 260-fold in higher molecular weight (HMW) species. For continuous TCZR-HIC, the TCZ was moved 49–58 times during uninterrupted loading of BSA feeds at 0.25, 0.5 or 1 mg·mL-1. Each TCZ movement generated a sharp symmetrical elution peak. In the best case, (condition 1: 0.25 mg·mL-1 BSA; >17 mg BSA applied per mL of bed) the height of TCZ elution peaks approached pseudo-steady midway through the loading phase with no rise in baseline UV280 signal between peaks. Peak composition remained constant averaging 94.4% monomer, 5.6% 2–4 mers and <0.05% HMW. Monomers were recovered in quantitative yield depleted >3.1 fold in 2–4 mers and 92-fold in HMW species cf. the feed (63.6% monomers, 21.8% 2–4 mers, 14.6% HMW). However, increasing the BSA concentration to 1 mg·mL-1 (condition 2) or employing a fouled HIC column with 0.5 mg·mL-1 BSA (condition 3) compromised monomer purification performance.

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.

Effect and mechanism of Qingre Huashi decoction on drug-resistant Helicobacter pylori.

Helicobacter pylori (HP), the most common pathogenic microorganism in the stomach, can induce inflammatory reactions in the gastric mucosa, causing chronic gastritis and even gastric cancer. HP infection affects over 4.4 billion people globally, with a worldwide infection rate of up to 50%. The multidrug resistance of HP poses a serious challenge to eradication. It has been de-monstrated that compared to bismuth quadruple therapy, Qingre Huashi decoction (QHD) combined with triple therapy exhibits comparable eradication rates but with a lower incidence of adverse reactions; in addition, QHD can directly inhibit and kill HP in vitro. To explore the effect and mechanism of QHD on clinically multidrug-resistant and strong biofilm-forming HP. In this study, 12 HP strains were isolated in vitro after biopsy during gastroscopy of HP-infected patients. In vitro, the minimum inhibitory concentration (MIC) values for clinical HP strains and biofilm quantification were determined through the E-test method and crystal violet staining, respectively. The most robust biofilm-forming strain of HP was selected, and QHD was evaluated for its inhibitory and bactericidal effects on the strain with strong biofilm formation. This assessment was performed using agar dilution, E-test, killing dynamics, and transmission electron microscopy (TEM). The study also explored the impact of QHD on antibiotic resistance in these HP strains with strong biofilm formation. Crystalline violet method, scanning electron microscopy, laser confocal scanning microscopy, and (p)ppGpp chromatographic identification were employed to evaluate the effect of QHD on biofilm in strong biofilm-forming HP strains. The effect of QHD on biofilm and efflux pump-related gene expression was evaluated by quantitative polymerase chain reaction. Non-targeted metabolomics with UHPLC-MS/MS was used to identify potential metabolic pathways and biomarkers which were different between the NC and QHD groups. HP could form biofilms of different degrees in vitro, and the intensity of formation was associated with the drug resistance of the strain. QHD had strong bacteriostatic and bactericidal effects on HP, with MICs of 32-64 mg/mL. QHD could inhibit the biofilm formation of the strong biofilm-forming HP strains, disrupt the biofilm structure, lower the accumulation of (p)ppGpp, decrease the expression of biofilm-related genes including LuxS, Spot, glup (HP1174), NapA, and CagE, and reduce the expression of efflux pump-related genes such as HP0605, HP0971, HP1327, and HP1489. Based on metabolomic analysis, QHD induced oxidative stress in HP, enhanced metabolism, and potentially inhibited relevant signaling pathways by upregulating adenosine monophosphate (AMP), thereby affecting HP growth, metabolism, and protein synthesis. QHD exerts bacteriostatic and bactericidal effects on HP, and reduces HP drug resistance by inhibiting HP biofilm formation, destroying its biofilm structure, inhibiting the expression of biofilm-related genes and efflux pump-related genes, enhancing HP metabolism, and activating AMP in HP.

Effect of Ce addition on the nucleation and growth of austenite in ultra-high-strength steel

The effect of varying rare earth element cerium (Ce) contents (0∼0.0792 wt%) on the austenite grain size of ultra-high-strength engineering steel has been studied under different austenitization conditions (holding time of 5∼360 min at temperatures ranging from 900 °C to 1200 °C). Results show that the addition of Ce can refine grains, and the refining effect becomes more pronounced as the Ce content increases. The inhibition of austenite grain growth by fine Ce-containing inclusions during the holding process has been observed through laser scanning confocal microscopy (LSCM) and field-emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectrometer (EDS), and the pinning effect of Ce-containing inclusions on the austenite grain boundaries is the primary factor for the refinement of austenite grains. Besides, theoretical calculations have shown that the lattice misfits between the (100) plane of CeP and the (111) plane of the γ-phase is 7.83%, indicating that CeP could serve as a heterogeneous nucleation core for the γ-phase and was moderately effective. Furthermore, the uniformization effect of Ce on the grains is more prominent than the refining effect at the holding temperatures of 1000 °C and 1200 °C.

Image scanning microscopy using radially polarized beam with polarization conversion

Image scanning microscopy (ISM), which combines the confocal scanning microscopy (CSM) with fast wide-field CCD detection, has been demonstrated in the fluorescent imaging, achieving both high resolution and signal to noise ratio (SNR). In this paper, we introduce radially polarized beam to ISM for non-fluorescent imaging. Radially polarized beam is applied to obtain a sharper illumination point spread function (PSF), along with a polarization converter to enhance detection PSF. It is found that the lateral resolution of ISM using radially polarized beam with polarization conversion (RPC-ISM) is improved to 0.28λ by a factor of 20%, as compared to traditional CSM. Further, images of complex object structures are simulated based on the complete model of scanning microscopy. Simulation results indicate an enhanced transverse resolution in RPC-ISM, compared with conventional ISM using circularly polarized beam. This technique can be used for label-free imaging such as semiconductor inspection, nano-lithography and so on.