scholarly journals The effect of the dispersion of microfibrillated cellulose on the mechanical properties of melt-compounded polypropylene–polyethylene copolymer

Cellulose ◽  
2019 ◽  
Vol 26 (18) ◽  
pp. 9645-9659 ◽  
Author(s):  
Caterina Palange ◽  
Marcus A. Johns ◽  
David J. Scurr ◽  
Jonathan S. Phipps ◽  
Stephen J. Eichhorn
Keyword(s):  
Tannic Acid ◽  
Laser Scanning ◽  
Secondary Ion Mass Spectrometry ◽  
High Surface ◽  
Microfibrillated Cellulose ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cellulose Content ◽  
Reinforced Composites ◽  
The Impact

Abstract Microfibrillated cellulose (MFC) is a highly expanded, high surface area networked form of cellulose-based reinforcement. Due to the poor compatibility of cellulose with most common apolar thermoplastic matrices, the production of cellulose-reinforced composites in industry is currently limited to polar materials. In this study, a facile water-based chemistry, based on the reaction of MFC with tannic acid and subsequent functionalisation with an alkyl amine, is used to render the surface of the MFC fibrils hydrophobic and enhance the dispersion of the cellulose-based filler into an apolar thermoplastic matrix. The level of dispersion of the compatibilized MFC reinforced composites was evaluated using Time of Flight Secondary Ion Mass Spectrometry and multi-channel Spectral Confocal Laser Scanning Microscopy. The agglomeration of cellulosic filler within the composites was reduced by functionalising the surface of the MFC fibrils with tannic acid and octadecylamine. The resulting composites exhibited an increase in modulus at a high cellulose content. Despite the dispersion of a large portion of the functionalised filler, the presence of some remaining aggregates affected the impact properties of the composites produced.

Confocal and SEM imaging to demonstrate food pathogen- biofilm biocontrol by pyocyanin from Pseudomonas aeruginosa BTRY1

2016 ◽  
Vol 6 (01) ◽  
pp. 5218
Author(s):  
Laxmi Mohandas ◽  
Anju T. R. ◽  
Sarita G. Bhat*
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Antibiofilm Activity ◽  
Opportunistic Pathogens ◽  
Redox Active ◽  
Sem Imaging ◽  
The Impact

An assortment of redox-active phenazine compounds like pyocyanin with their characteristic blue-green colour are synthesized by Pseudomonas aeruginosa, Gram-negative opportunistic pathogens, which are also considered one of the most commercially valuable microorganisms. In this study, pyocyanin from Pseudomonas aeruginosa BTRY1 from food sample was assessed for its antibiofilm activity by micro titer plate assay against strong biofilm producers belonging to the genera Bacillus, Staphylococcus, Brevibacterium and Micrococcus. Pyocyanin inhibited biofilm activity in very minute concentrations. This was also confirmed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Both SEM and CLSM helped to visualize the biocontrol of biofilm formation by eight pathogens. The imaging and quantification by CLSM also established the impact of pyocyanin on biofilm-biocontrol mainly in the food industry.

scholarly journals From Macro to Mesoporous ZnO Inverse Opals: Synthesis, Characterization and Tracer Diffusion Properties

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 196
Author(s):  
Shravan Kousik ◽  
Diane Sipp ◽  
Karina Abitaev ◽  
Yawen Li ◽  
Thomas Sottmann ◽  
...  
Keyword(s):  
Open Porosity ◽  
Laser Scanning ◽  
High Surface ◽  
Stop Band ◽  
Correlation Spectroscopy ◽  
Laser Scanning Microscopy ◽  
Added Value ◽  
Confocal Laser ◽  
Inverse Opals ◽  
Mesoporous Zno

Oxide inverse opals (IOs) with their high surface area and open porosity are promising candidates for catalyst support applications. Supports with confined mesoporous domains are of added value to heterogeneous catalysis. However, the fabrication of IOs with mesoporous or sub-macroporous voids (<100 nm) continues to be a challenge, and the diffusion of tracers in quasi-mesoporous IOs is yet to be adequately studied. In order to address these two problems, we synthesized ZnO IOs films with tunable pore sizes using chemical bath deposition and template-based approach. By decreasing the size of polystyrene (PS) template particles towards the mesoporous range, ZnO IOs with 50 nm-sized pores and open porosity were synthesized. The effect of the template-removal method on the pore geometry (spherical vs. gyroidal) was studied. The infiltration depth in the template was determined, and the factors influencing infiltration were assessed. The crystallinity and photonic stop-band of the IOs were studied using X-Ray diffraction and UV-Vis, respectively. The infiltration of tracer molecules (Alexa Fluor 488) in multilayered quasi-mesoporous ZnO IOs was confirmed via confocal laser scanning microscopy, while fluorescence correlation spectroscopy analysis revealed two distinct diffusion times in IOs assigned to diffusion through the pores (fast) and adsorption on the pore walls (slow).

scholarly journals Mosaic-CLSM Assessment of Bacterial Spatial Distribution in Cosmetic Matrices According to Matrix Viscosity and Bacterial Hydrophobicity

Cosmetics ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 32
Author(s):  
Samia Almoughrabie ◽  
Chrisse Ngari ◽  
Romain Briandet ◽  
Valérie Poulet ◽  
Florence Dubois-Brissonnet
Keyword(s):  
Spatial Distribution ◽  
Laser Scanning ◽  
Rapid Assessment ◽  
Challenge Test ◽  
Surface Hydrophobicity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Surface ◽  
Bacterial Hydrophobicity ◽  
The Impact

The reliability of the challenge test depends, among other parameters, on the spatial distribution of microorganisms in the matrix. The present study aims to quickly identify factors that are susceptible to impair a uniform distribution of inoculated bacteria in cosmetic matrices in this context. We used mosaic confocal laser scanning microscopy (M-CLSM) to obtain rapid assessment of the impact of the composition and viscosity of cosmetic matrices on S. aureus spatial distribution. Several models of cosmetic matrices were formulated with different concentrations of two thickeners and were inoculated with three S. aureus strains having different levels of hydrophobicity. The spatial distribution of S. aureus in each matrix was evaluated according to the frequency distribution of the fluorescence values of at least 1350 CLSM images. We showed that, whatever the thickener used, an increasingly concentration of thickener results in increasingly bacterial clustered distribution. Moreover, higher bacterial hydrophobicity also resulted in a more clustered spatial distribution. In conclusion, CLSM-based method allows a rapid characterization of bacterial spatial distribution in complex emulsified systems. Both matrix viscosity and bacterial surface hydrophobicity affect the bacterial spatial distribution which can have an impact on the reliability of bacterial enumeration during challenge test.

scholarly journals Electrochemical and surface analytical techniques applied to microbiologically influenced corrosion investigation

2018 ◽  
Vol 36 (4) ◽  
pp. 349-363 ◽  
Author(s):  
László Trif ◽  
Abdul Shaban ◽  
Judit Telegdi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Laser Scanning ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Analytical Techniques ◽  
Laser Scanning Microscopy ◽  
Microbiologically Influenced Corrosion ◽  
Microbial Consortia ◽  
Confocal Laser ◽  
The Impact

AbstractSuitable application of techniques for detection and monitoring of microbiologically influenced corrosion (MIC) is crucial for understanding the mechanisms of the interactions and for selecting inhibition and control approaches. This paper presents a review of the application of electrochemical and surface analytical techniques in studying the MIC process of metals and their alloys. Conventional electrochemical techniques, such as corrosion potential (Ecorr), redox potential, dual-cell technique, polarization curves, electrochemical impedance spectroscopy (EIS), electrochemical noise (EN) analysis, and microelectrode techniques, are discussed, with examples of their use in various MIC studies. Electrochemical quartz crystal microbalance, which is newly used in MIC study, is also discussed. Microscopic techniques [scanning electron microscopy (SEM), environmental SEM (ESEM), atomic force microscopy (AFM), confocal laser microscopy (CLM), confocal laser scanning microscopy (CLSM), confocal Raman microscopy] and spectroscopic analytical methods [Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS)] are also highlighted. This review highlights the heterogeneous characteristics of microbial consortia and use of special techniques to study their probable effects on the metal substrata. The aim of this review is to motivate using a combination of new procedures for research and practical measurement and calculation of the impact of MIC and biofilms on metals and their alloys.

scholarly journals Pili and other surface proteins influence the structure and the nanomechanical properties of Lactococcus lactis biofilms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ibrahima Drame ◽  
Christine Lafforgue ◽  
Cecile Formosa-Dague ◽  
Marie-Pierre Chapot-Chartier ◽  
Jean-Christophe Piard ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Laser Scanning ◽  
Binding Proteins ◽  
Binding Protein ◽  
Young Modulus ◽  
Surface Proteins ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
The Impact

AbstractLactic acid bacteria, in particular Lactococcus lactis, are widely used in the food industry, for the control and/or the protection of the manufacturing processes of fermented food. While L. lactis has been reported to form compact and uniform biofilms it was recently shown that certain strains able to display pili at their surface form more complex biofilms exhibiting heterogeneous and aerial structures. As the impact of those biofilm structures on the biomechanical properties of the biofilms is poorly understood, these were investigated using AFM force spectroscopy and imaging. Three types of strains were used i.e., a control strain devoid of pili and surface mucus-binding protein, a strain displaying pili but no mucus-binding proteins and a strain displaying both pili and a mucus-binding protein. To identify potential correlations between the nanomechanical measurements and the biofilm architecture, 24-h old biofilms were characterized by confocal laser scanning microscopy. Globally the strains devoid of pili displayed smoother and stiffer biofilms (Young Modulus of 4–100 kPa) than those of piliated strains (Young Modulus around 0.04–0.1 kPa). Additional display of a mucus-binding protein did not affect the biofilm stiffness but made the biofilm smoother and more compact. Finally, we demonstrated the role of pili in the biofilm cohesiveness by monitoring the homotypic adhesion of bacteria to the biofilm surface. These results will help to understand the role of pili and mucus-binding proteins withstanding external forces.

scholarly journals Protozoan impact on bacterial biofilm formation

2010 ◽  
Vol 47 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Krzysztof Rychert ◽  
Thomas Neu
Keyword(s):  
Activated Sludge ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Grazing Pressure ◽  
Bacterial Biofilm ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Protozoan Community ◽  
Biofilm Development ◽  
The Impact

Protozoan impact on bacterial biofilm formationConfocal laser scanning microscopy in combination with digital image analysis was used to assess the impact of protozoa on bacterial colonisation of surfaces. Bacterial biofilms were developed from activated sludge in microscope flow cells and were exposed to the grazing pressure of protozoa. The protozoan community from healthy activated sludge and a culture of flagellateBodo saltanswere used as grazers. Experiments comprised 48-h incubations in 3 treatment variants: bacteria with protozoa, bacteria with protozoa added after some time and bacteria without protozoa. When necessary, the elimination of protozoa from the inoculum was carried out with cycloheximide and NiSO4. Experiments demonstrated that protozoa from healthy activated sludge initially disturbed the biofilm development but later they could stimulate its growth. Similar results could be established in the experiment withBodo saltans(inoculum: 1000 cells/ml), however differences were not statistically significant. The finding that protozoa support biofilm development during specific stages may be relevant for biofilm studies with mixed environmental biofilm communities.

scholarly journals Active and inactive genes localize preferentially in the periphery of chromosome territories.

1996 ◽  
Vol 135 (5) ◽  
pp. 1195-1205 ◽  
Author(s):  
A Kurz ◽  
S Lampel ◽  
J E Nickolenko ◽  
J Bradl ◽  
A Benner ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Cell Types ◽  
Chromosome Territory ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Chromosome Territories ◽  
Inactive Genes ◽  
Different Cell Types ◽  
The Impact

The intranuclear position of a set of genes was analyzed with respect to the territories occupied by the whole chromosomes in which these genes are localized. Genes and their respective chromosome territories were simultaneously visualized in three-dimensionally preserved nuclei applying dual color fluorescence in situ hybridization. Three coding (DMD, MYH7, and HBB) and two noncoding sequences (D1Z2 and an anonymous sequence) were analyzed in four different cell types, including cells where DMD and MYH7 are actively transcribed. Spatial analysis by confocal laser scanning microscopy revealed that the genes are preferentially located in the periphery of chromosome territories. This positioning was independent from the activity of the genes. In contrast, the non-expressed anonymous fragment was found randomly distributed or localized preferentially in the interior of the corresponding chromosome territory. Furthermore, the distribution of the analyzed genes within the territorial peripheries was found to be highly characteristic for each gene, and, again, independent from its expression. The impact of these findings with regard to the three-dimensional arrangement of the linear DNA string within chromosome territories, as well as with respect to a putative nuclear subcompartment confining gene expression, are discussed.

scholarly journals Temperature-Dependent Influence of FliA Overexpression on PHL628 E. coli Biofilm Growth and Composition

2021 ◽  
Vol 11 ◽  
Author(s):  
Luke D. Buck ◽  
Maddison M. Paladino ◽  
Kyogo Nagashima ◽  
Emma R. Brezel ◽  
Joshua S. Holtzman ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Laser Scanning ◽  
Protein Composition ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Structural Protein ◽  
Biofilm Growth ◽  
E Coli ◽  
Biofilm Production ◽  
The Impact

Biofilm growth and survival pose a problem in both medical and industrial fields. Bacteria in biofilms are more tolerant to antibiotic treatment due to the inability of antibiotics to permeate to the bottom layers of cells in a biofilm and the creation of altered microenvironments of bacteria deep within the biofilm. Despite the abundance of information we have about E. coli biofilm growth and maturation, we are still learning how manipulating different signaling pathways influences the formation and fitness of biofilm. Understanding the impact of signaling pathways on biofilm formation may narrow the search for novel small molecule inhibitors or activators that affect biofilm production and stability. Here, we study the influence of the minor sigma transcription factor FliA (RpoF, sigma-28), which controls late-stage flagellar assembly and chemotaxis, on biofilm production and composition at various temperatures in the E. coli strain PHL628, which abundantly produces the extracellular structural protein curli. We examined FliA’s influence on external cellular structures like curli and flagella and the biomolecular composition of the biofilm’s extracellular polymeric substance (EPS) using biochemical assays, immunoblotting, and confocal laser scanning microscopy (CLSM). At 37°C, FliA overexpression results in the dramatic growth of biofilm in polystyrene plates and more modest yet significant biofilm growth on silica slides. We observed no significant differences in curli concentration and carbohydrate concentration in the EPS with FliA overexpression. Still, we did see significant changes in the abundance of EPS protein using CLSM at higher growth temperatures. We also noticed increased flagellin concentration, a major structural protein in flagella, occurred with FliA overexpression, specifically in planktonic cultures. These experiments have aided in narrowing our focus to FliA’s role in changing the protein composition of the EPS, which we will examine in future endeavors.

Hyperbaric oxygen downregulates ICAM-1 expression induced by hypoxia and hypoglycemia: the role of NOS

2000 ◽  
Vol 278 (2) ◽  
pp. C292-C302 ◽  
Author(s):  
Jon A. Buras ◽  
Gregory L. Stahl ◽  
Kathy K. H. Svoboda ◽  
Wende R. Reenstra
Keyword(s):  
Endothelial Cell ◽  
Hyperbaric Oxygen ◽  
Laser Scanning ◽  
Cell Model ◽  
Ischemia Reperfusion ◽  
Laser Scanning Microscopy ◽  
Intercellular Adhesion Molecule ◽  
Confocal Laser ◽  
Bovine Aortic Endothelial Cell ◽  
The Impact

Hyperbaric oxygen (HBO) is being studied as a therapeutic intervention for ischemia/reperfusion (I/R) injury. We have developed an in vitro endothelial cell model of I/R injury to study the impact of HBO on the expression of intercellular adhesion molecule-1 (ICAM-1) and polymorphonuclear leukocyte (PMN) adhesion. Human umbilical vein endothelial cell (HUVEC) and bovine aortic endothelial cell (BAEC) induction of ICAM-1 required simultaneous exposure to both hypoxia and hypoglycemia as determined by confocal laser scanning microscopy, ELISA, and Western blot. HBO treatment reduced the expression of ICAM-1 to control levels. Adhesion of PMNs to BAECs was increased following hypoxia/hypoglycemia exposure (3.4-fold, P < 0.01) and was reduced to control levels with exposure to HBO ( P = 0.67). Exposure of HUVECs and BAECs to HBO induced the synthesis of endothelial cell nitric oxide synthase (eNOS). The NOS inhibitor nitro-l-arginine methyl ester attenuated HBO-mediated inhibition of ICAM-1 expression. Our findings suggest that the beneficial effects of HBO in treating I/R injury may be mediated in part by inhibition of ICAM-1 expression through the induction of eNOS.

scholarly journals The Protective Effect of Staphylococcus epidermidis Biofilm Matrix against Phage Predation

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1076
Author(s):  
Luís D. R. Melo ◽  
Graça Pinto ◽  
Fernando Oliveira ◽  
Diana Vilas-Boas ◽  
Carina Almeida ◽  
...  
Keyword(s):  
Protective Effect ◽  
Staphylococcus Epidermidis ◽  
Laser Scanning ◽  
3D Structure ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Planktonic Cells ◽  
The Matrix ◽  
The Impact ◽  
Biofilm Matrix

Staphylococcus epidermidis is a major causative agent of nosocomial infections, mainly associated with the use of indwelling devices, on which this bacterium forms structures known as biofilms. Due to biofilms’ high tolerance to antibiotics, virulent bacteriophages were previously tested as novel therapeutic agents. However, several staphylococcal bacteriophages were shown to be inefficient against biofilms. In this study, the previously characterized S. epidermidis-specific Sepunavirus phiIBB-SEP1 (SEP1), which has a broad spectrum and high activity against planktonic cells, was evaluated concerning its efficacy against S. epidermidis biofilms. The in vitro biofilm killing assays demonstrated a reduced activity of the phage. To understand the underlying factors impairing SEP1 inefficacy against biofilms, this phage was tested against distinct planktonic and biofilm-derived bacterial populations. Interestingly, SEP1 was able to lyse planktonic cells in different physiological states, suggesting that the inefficacy for biofilm control resulted from the biofilm 3D structure and the protective effect of the matrix. To assess the impact of the biofilm architecture on phage predation, SEP1 was tested in disrupted biofilms resulting in a 2 orders-of-magnitude reduction in the number of viable cells after 6 h of infection. The interaction between SEP1 and the biofilm matrix was further assessed by the addition of matrix to phage particles. Results showed that the matrix did not inactivate phages nor affected phage adsorption. Moreover, confocal laser scanning microscopy data demonstrated that phage infected cells were less predominant in the biofilm regions where the matrix was more abundant. Our results provide compelling evidence indicating that the biofilm matrix can work as a barrier, allowing the bacteria to be hindered from phage infection.

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