scholarly journals Modification of Olive Leaves’ Surface by Ultrasound Cavitation. Correlation with Polyphenol Extraction Enhancement

2020 ◽  
Vol 11 (1) ◽  
pp. 232
Author(s):  
Natacha Rombaut ◽  
Tony Chave ◽  
Sergey I. Nikitenko ◽  
Mohamed El Maâtaoui ◽  
Anne Sylvie Fabiano-Tixier ◽  
...  
Keyword(s):  
Cross Sections ◽  
Leaf Surface ◽  
Environmental Scanning Electron Microscopy ◽  
Acoustic Cavitation ◽  
Environmental Scanning ◽  
Plant Structure ◽  
Olive Leaves ◽  
Treated Leaf ◽  
Polyphenol Extraction ◽  
The Impact

We investigated the impact of ultrasound at 20 kHz on olive leaves to understand how acoustic cavitation could increase polyphenol extraction. Application of ultrasound to whole leaf from 5 to 60 min enabled us to increase extraction from 6.96 to 48.75 µg eq. oleuropein/mL of extract. These results were correlated with Environmental Scanning Electron Microscopy, allowing for leaf surface observation and optical microscopy of treated leaf cross sections to understand histochemical modifications. Our observations suggest that the effectiveness of ultrasound applied to extraction is highly dependent on plant structure and on how this material will react when subjected to acoustic cavitation. Ultrasound seems to impact the leaves by two mechanisms: cuticle erosion, and fragmentation of olive leaf surface protrusions (hairs), which are both polyphenol-rich structures.

Removal of Aflatoxin B1 and Inhibition of Aspergillus flavus Growth by the Use of Lactobacillus plantarum on Olives

2014 ◽  
Vol 77 (10) ◽  
pp. 1760-1767 ◽  
Author(s):  
FATEN KACHOURI ◽  
HAMIDA KSONTINI ◽  
MOKTAR HAMDI
Keyword(s):  
Lactobacillus Plantarum ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
High Performance ◽  
Environmental Scanning Electron Microscopy ◽  
Total Phenolic ◽  
Environmental Scanning ◽  
Fluorescence Detector ◽  
Natural Microflora ◽  
The Impact

Olives can be contaminated with a wide variety of molds (Aspergillus and/or Penicillium) that can be occurring naturally on fresh and processed olives and could support mycotoxin production. The aim of this work was to investigate aflatoxin B1 (AFB1) production by fungi and its bioaccumulation in olives during storage and to study the impact of the application of Lactobacillus plantarum on the inhibition of mold development and production of AFB1. Two different treatments were applied: (i) olives with natural microflora and (ii) olives inoculated with Aspergillus flavus after elimination of natural microflora. AFB1 has been extracted from olives and quantitated by high-performance liquid chromatography using a fluorescence detector. Results showed the absence of this metabolite in the olives for the season 2008 to 2009. In 2009 to 2010, AFB1 was detected at the level of 11 μg/kg. The application of L. plantarum during the storage of olives favors the reduction of the level of AFB1 to 5.9 μg/kg correlated with a decrease in the amount of molds (86.3%). The images obtained by environmental scanning electron microscopy showed that L. plantarum was able to adhere to the olive surface and probably produce a biofilm that inhibits the multiplication of yeast and fungi by oxygen competition. Results showed an increase of antioxidant activity and amount of total phenolic compounds of olives, respectively, by 24 and 8.6%. In many olives contaminated with A. flavus, AFB1 was present at an initial level of 5.15 μg/kg and increased to 6.55 μg/kg after 8 days of storage. The biological detoxification of AFB1 in olives by L. plantarum is confirmed by the reduction of the level of AFB1 to 2.12 μg/kg on day 0 and its absence after 4 days of storage.

scholarly journals Aesthetic Alteration of Marble Surfaces Caused by Biofilm Formation: Effects of Chemical Cleaning

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 122 ◽  
Author(s):  
Federica Villa ◽  
Davide Gulotta ◽  
Lucia Toniolo ◽  
Luigimaria Borruso ◽  
Cristina Cattò ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Specific Substrate ◽  
Chemical Cleaning ◽  
Aesthetic Results ◽  
Cleaning Procedures ◽  
Functional Profiles ◽  
The Impact ◽  
Cleaning Treatment

Despite the massive presence of biofilms causing aesthetic alteration to the façade of the Monza Cathedral, our team in a previous work proved that the biocolonization was not a primary damaging factor if compared to chemical-physical deterioration due to the impact of air pollution. Nonetheless, the conservators tried to remove the sessile dwelling microorganisms to reduce discolouration. In this research, two nearby sculpted leaves made of Candoglia marble were selected to study the effects of a chemical treatment combining the biocides benzalkonium chloride, hydrogen peroxide and Algophase® and mechanical cleaning procedures. One leaf was cleaned with the biocides and mechanically, and the other was left untreated as control. The impact of the treatment was investigated after 1 month from the cleaning by digital microscopy, environmental scanning electron microscopy, confocal microscopy and molecular methods to determine the composition and the functional profiles of the bacterial communities. Despite the acceptable aesthetic results obtained, the overall cleaning treatment was only partially effective in removing the biofilm from the colonized surfaces and, therefore, not adequately suitable for the specific substrate. Furthermore, the cleaning process selected microorganisms potentially more resistant to biocides so that the efficacy of future re-treatment by antimicrobial agents could be negatively affected.

scholarly journals Influence of Low-Pressure Treatment on the Morphological and Compositional Stability of Microscopic Ettringite

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2720
Author(s):  
Patrick A. Kißling ◽  
Franziska Lübkemann ◽  
Tabea von Bronk ◽  
Dario Cotardo ◽  
Lei Lei ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Environmental Scanning Electron Microscopy ◽  
Bound Water ◽  
Low Pressure ◽  
Environmental Scanning ◽  
Pressure Treatment ◽  
X Ray Diffraction ◽  
Compositional Stability ◽  
Drying Conditions ◽  
The Impact

The impact of low-pressure treatment on the crystal structure, morphology, and chemical composition of ettringite, due to their major importance with respect to processability (i.a., drying conditions) and to the analysis of ettringite-containing samples, is examined utilizing X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and environmental scanning electron microscopy. Synthetic ettringite was treated for various durations (5 min up to 72 h) and at two different levels of low-pressure (4.0 mbar and 60 µbar). Evaluation showed a correlation between the procedural parameters (time and pressure), the chemical composition, and the morphology of ettringite. The experiments reveal that, when exposed to 4 mbar pressure, nearly no changes occur in the ettringite’s morphology, whereas the crystals undergo swelling and slight deformations at very low pressures (60 µbar and 35.3 nbar), which is attributed to the loss of bound water and the partial transformation from ettringite to quicklime, anhydrite, and calcium aluminate. Furthermore, the strongly dehydrated ettringite shows the same morphology.

Environmental Scanning Electron Microscopy as a Tool to Study Shrinkage Microcracks in Cement-Based Materials

1999 ◽  
Vol 589 ◽  
Author(s):  
J. Bisschop ◽  
J.G.M. Van Mier
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Relative Humidity ◽  
Cross Sections ◽  
Preparation Method ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Sample Preparation Method ◽  
Cement Based Materials ◽  
Scanning Electron

AbstractIn this paper a method is described to observe shrinkage microcracks on ‘wet’ specimen cross-sections of cement-based materials with Environmental Scanning Electron Microscopy (ESEM). A sample cooling device which can be used in the ESEM chamber was built to control the relative humidity above a microscope sample. The accuracy of measuring relative humidity is determined to be 5% at a sample temperature of 3°C. A microscope sample preparation method and a pump-down sequence of the ESEM-chamber, both without any drying of the sample, are described. Preliminary results show that in the studied mortar the visibility of shrinkage microcracks on a ‘wet’ specimen cross-section is low due to closure of microcracks by swelling of the cement paste.

Charge Contrast: Some ESEM Observations of A New/Old Phenomenon

1998 ◽  
Vol 4 (S2) ◽  
pp. 292-293 ◽  
Author(s):  
Eric Doehne
Keyword(s):  
Cross Sections ◽  
Secondary Electron ◽  
Low Voltage ◽  
Environmental Scanning Electron Microscopy ◽  
Personal Communication ◽  
Environmental Scanning ◽  
Contrast Imaging ◽  
The Past ◽  
Contrast Mechanisms ◽  
Scanning Electron

Over the past few years there have been occasional reports of unusual secondary electron contrasts in certain nonmetallic materials using conventional (CSEM-Johansen et al, 1997), low voltage (LV-SEM-Harker et al, 1993; Harker et al, 1994) and environmental scanning electron microscopy (ESEM-Griffin, 1997; T. Hardt, personal communication) which have documented novel contrast mechanisms whose origins are not yet well understood. Indeed, similar observations were made over 20 years ago in certain uncoated materials (such as SiC) using conventional SEM (Sawyer and Page, 1978). Aspects of these charge contrast imaging (CCI) phenomena are further documented here in a series of ESEM experiments on polished cross sections of uncoated travertine calcite. What is “old” is the fact that these contrasts have been reported on several occasions. What is “new” is the observation that these unusual contrasts are more readily studied and, in some cases, have been found in a wider range of materials using ESEM.

Structural changes in spruce wood during different steps of steam explosion pretreatment

Holzforschung ◽  
2015 ◽  
Vol 69 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Muhammad Muzamal ◽  
Kerstin Jedvert ◽  
Hans Theliander ◽  
Anders Rasmuson
Keyword(s):  
Steam Explosion ◽  
Structural Changes ◽  
Mercury Porosimetry ◽  
Environmental Scanning Electron Microscopy ◽  
Steam Treatment ◽  
Environmental Scanning ◽  
Wood Material ◽  
Spruce Wood ◽  
Pretreatment Technology ◽  
The Impact

Abstract Steam explosion (SE) is a promising hydrothermal pretreatment technology for future biorefineries. In this study, the three steps of the steam explosion process, (1) the steam treatment (2) the explosion, and (3) the impact step were separately considered and their effects on structural changes of wood were studied. The SE experiments were performed on single wood pieces in different experimental set-ups at 7 and 14 bar pressure with 5 and 10 min treatment times. Mercury porosimetry and environmental scanning electron microscopy analyses were conducted to characterise both internal and external changes in the wood. It was found that the explosion step is not responsible for the disintegration of the wood material into small pieces; instead, the disintegration occurs due to impact of softened wood chips. However, the porosity profiles of the tracheids change during the explosion step. Altogether, all three steps of the SE process contribute in a synergistic way to an increase in pore size and total intrusion volume.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

Detector strategies for environmental scanning electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1296-1297
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Vacuum ◽  
Environmental Scanning Electron Microscopy ◽  
Charge Carriers ◽  
Environmental Scanning ◽  
Surface Information ◽  
X Ray ◽  
Detector Electrode ◽  
Electrons And Ions ◽  
Low Energy Electrons ◽  
Environmental Sem

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.

The efficiency of application of virtual cross-sections method and hypotheses MELS in problems of wave signal propagation in elastic waveguides with rough surfaces

2016 ◽  
pp. 3564-3575 ◽  
Author(s):  
Ara Sergey Avetisyan
Keyword(s):  
Half Space ◽  
Cross Sections ◽  
Classical Method ◽  
Signal Propagation ◽  
Elastic Half Space ◽  
Layered Systems ◽  
Surface Layers ◽  
Inhomogeneous Surface ◽  
Wave Signal ◽  
The Impact

The efficiency of virtual cross sections method and MELS (Magneto Elastic Layered Systems) hypotheses application is shown on model problem about distribution of wave field in thin surface layers of waveguide when plane wave signal is propagating in it. The impact of surface non-smoothness on characteristics of propagation of high-frequency horizontally polarized wave signal in isotropic elastic half-space is studied. It is shown that the non-smoothness leads to strong distortion of the wave signal over the waveguide thickness and along wave signal propagation direction as well.  Numerical comparative analysis of change in amplitude and phase characteristics of obtained wave fields against roughness of weakly inhomogeneous surface of homogeneous elastic half-space surface is done by classical method and by proposed approach for different kind of non-smoothness.

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