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.

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 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.

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.

Hydro-mechanical properties of Calcigel-polyacrylamide composites

Clay Minerals ◽  
2015 ◽  
Vol 50 (3) ◽  
pp. 377-389 ◽  
Author(s):  
Hanna Haase ◽  
Tom Schanz
Keyword(s):  
Sorption Capacity ◽  
Structural Changes ◽  
Void Ratio ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Maximum Sorption Capacity ◽  
Face To Face ◽  
Maximum Sorption ◽  
The Individual ◽  
Scanning Electron

AbstractCalcigel bentonite-polyacrylamide (PAA) composites were investigated for their formation characteristics and their macroscopic hydro-mechanical and microscopic structural properties. The composites prepared were different in terms of the polymer charge, i.e. cationic (PAA+), anionic (PAA−), non-ionic (PAA°) and in terms of the polymer-to-clay ratio. The latter varied according to the individual maximum sorption capacity established from adsorption isotherms. Oedometer and waterretention testswere conducted on composites prepared under initial slurry conditions. The microstructure of the composites was investigated using environmental scanning electron microscopy (ESEM). At low stress, distinctly increased void ratios were found for all types of the composites, whereas under highstress conditions only the PAA+-composite prepared at 100% of the maximum sorption capacity showed an increase in void ratio. Analyses by ESEM on this composite indicated structural changes related to the preferential face-to-face aggregation, which help to explain the macroscopic behaviour and also account for the increased hydraulic permeabilities observed.

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.

International trade: Research of the reasons for the fall

2019 ◽  
pp. 79-91 ◽  
Author(s):  
V. S. Nazarov ◽  
S. S. Lazaryan ◽  
I. V. Nikonov ◽  
A. I. Votinov
Keyword(s):  
Growth Rate ◽  
International Trade ◽  
Exchange Rate ◽  
Global Economy ◽  
Structural Changes ◽  
Global Value Chains ◽  
Value Chains ◽  
Negative Contribution ◽  
Basic Commodity ◽  
The Impact

The article assesses the impact of various factors on the growth rate of international trade. Many experts interpreted the cross-border flows of goods decline against the backdrop of a growing global economy as an alarming sign that indicates a slowdown in the processes of globalization. To determine the reasons for the dynamics of international trade, the decompositions of its growth rate were carried out and allowed to single out the effect of the dollar exchange rate, the commodities prices and global value chains on the change in the volume of trade. As a result, it was discovered that the most part of the dynamics of international trade is due to fluctuations in the exchange rate of the dollar and prices for basic commodity groups. The negative contribution of trade within global value chains in 2014 was also revealed. During the investigated period (2000—2014), such a picture was observed only in the crisis periods, which may indicate the beginning of structural changes in the world trade.

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