Acetyl Group Distribution in Acetylated Wood Investigated by Microautoradiography

Holzforschung ◽  
2001 ◽  
Vol 55 (3) ◽  
pp. 270-275 ◽  
Author(s):  
Marie Rosenqvist
Keyword(s):  
Cell Wall ◽  
Weight Gain ◽  
Acetic Anhydride ◽  
Wood Cell Wall ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Accurate Information ◽  
Concentration Gradients ◽  
Good Opportunity ◽  
Acetyl Group

Summary Sapwood of Scots pine (Pinus silvestris L.) was acetylated with 14C- and 3H-labelled acetic anhydride. The distribution of acetyl groups was investigated with microautoradiography and microautoradiographs were evaluated with ESEM, Environmental Scanning Electron Microscopy. The investigation showed that the impregnation of wood with radioisotope-labelled substances provides a good opportunity to investigate the location of substances covalently bonded to the wood material. Introduced 14C-labelled acetyl groups show an even distribution in the wood cell wall, with no discernible concentration gradients at acetylation levels of about 5, 15 and 20% weight gain. 3H-labelled acetyl groups show an even distribution in the wood cell wall at 15 and 20% weight gain, with no discernible concentration gradients. At the 5% weight gain level, however, an uneven distribution of 3H-labelled acetyl groups over the cell wall is observed. Nevertheless, the unevenness is random and no concentration gradient is discernible at this level. 3H with a relatively high resolution, 0.5–1 μm, compared to 14C with a resolution of 2–5 μm, gives more accurate information about where exactly the acetyl groups are situated in the wood cell wall. Acetic anhydride was evenly distributed when a full impregnation procedure was used. The chemical and physical properties of acetic anhydride allow a uniform penetration into the pine cell wall and a complete acetylation takes place when the specimens are heated.

Changes in the cell wall volume of a number of wood species due to reaction with acetic anhydride

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 138-142 ◽  
Author(s):  
Jin H. Kwon ◽  
Callum A.S. Hill ◽  
Graham A. Ormondroyd ◽  
Siti Karim
Keyword(s):  
Cell Wall ◽  
Acetic Anhydride ◽  
Molar Volume ◽  
Volume Change ◽  
Wood Species ◽  
Korean Pine ◽  
Volume Changes ◽  
Weight Percentage ◽  
Acetyl Group ◽  
Helium Pycnometry

Abstract A number of softwoods and hardwoods (beech, rubberwood, Corsican pine, Korean pine) were reacted with acetic anhydride to a variety of weight percentage gain (WPG) values and the volume change due to reaction was determined both by measurement of the external dimensions and by helium pycnometry. The volume change due to modification determined by helium pycnometry was found to be equal to that calculated, except for Corsican pine. The volume change as determined by the external dimensions was not a reliable method for determining cell-wall volume changes. The molar volume of the acetyl group in the cell wall was calculated over a range of WPG values, with volumes ranging from approximately 32 to 42 cm3 mol-1, depending on the wood species studied. The differences in acetyl molar volume observed between most wood species were significant.

scholarly journals Properties of chemically and mechanically isolated fibres of spruce (Picea abies [L.] Karst.). Part 1: Structural and chemical characterisation

Holzforschung ◽  
2005 ◽  
Vol 59 (2) ◽  
pp. 240-246 ◽  
Author(s):  
Ingo Burgert ◽  
Notburga Gierlinger ◽  
Tanja Zimmermann
Keyword(s):  
Cell Wall ◽  
Picea Abies ◽  
Environmental Scanning Electron Microscopy ◽  
Middle Lamella ◽  
Solid Wood ◽  
Wall Structure ◽  
Environmental Scanning ◽  
Cell Wall Assembly ◽  
Ir Microscopy ◽  
Mechanical Isolation

Abstract Single fibres of spruce (Picea abies [L.] Karst.) were isolated both chemically and mechanically from a solid wood sample. Mechanical isolation was carried out using very fine tweezers to peel out fibres, thereby taking advantage of the low shear strength between them. Chemical isolation was achieved using hydrogen peroxide and glacial acetic acid. Fibres were examined with Fourier-transform infrared (FT-IR) microscopy, and field-emission environmental scanning electron microscopy (FE-ESEM) in low-Vacuum mode to compare the isolation techniques with respect to their influence on cell wall structure and polymer assembly. The chemical treatment led to degradation of lignin and hemicelluloses, significantly influencing the cell wall assembly and structure. The cell wall polymers of mechanically isolated fibres remained in their natural constitution. As expected, the peeling process caused separation of cell wall layers. Our examinations indicate that delamination predominately took place at the interface between the secondary cell wall and the compound middle lamella. However, fracture between the S1 and S2 layers was examined as well. With respect to fibre quality, it was of particular importance that transverse crack propagation in the secondary cell walls (S2) was not observed.

Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit

2001 ◽  
Vol 7 (1) ◽  
pp. 59-71 ◽  
Author(s):  
G. O. Sozzi ◽  
A. A. Fraschina ◽  
M. A. Castro
Keyword(s):  
Cell Wall ◽  
Tomato Fruit ◽  
Environmental Scanning Electron Microscopy ◽  
Middle Lamella ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Environmental Scanning ◽  
High Electron ◽  
Exogenous Ethylene ◽  
Transgenic Tomatoes

The ultrastructural impact of low ethylene biosynthesis (less than 0.5% of normal levels) was evaluated in transgenic (A11.1) tomatoes ( Lycopersicon esculentumMill.) expressing an antisense 1-aminocyclopropane-1-carboxylic acid synthase (ACC-S) transgene by means of transmission and environmental scanning electron microscopy. In 48-day mature green fruit, no significant ultrastructural differences were found between transgenic and control tomatoes. In 78-day control fruit, which were overripe and showed deteriorated texture, many areas of the cytoplasm were devoid of structures, and micrographs showed cell collapse with folding and dissolution of the cell wall. On the other hand, in 90-day transgenic fruit, which were firm and not ripe, the cytoplasm showed a relatively high electron density. Plastids retained remnants of chloroplast thylakoids along with significant amounts of osmiophylic plastoglobuli, but lycopene was not detected. Conspicuous starch granules were observed in mature green transgenic tomatoes, but were not detected in 90-day chlorochromoplasts. Electron-dense regions reflecting the integrity of the middle lamella alternated with other partially degraded regions. This incipient dissolution of the middle lamella pectic polymers may be attributable to nonenzymatic deaggregation or to cell-wall hydrolases which could be ethylene independent or responsive to very low levels of ethylene. Besides, cells were attached along extended contact areas and appeared turgid. This feature may provide an explanation of firmness retention that does not solely involve cell walls. Disruption of the middle lamella and development of lycopene crystalloids were observed when exogenous ethylene (12 ppm) was applied.

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.

scholarly journals 616 Preventing Biofilms on BACTIGON® Coated Camstent Urinary Catheters in Patients Undergoing Elective Colorectal Surgery: A Single Centre Pilot Study

2021 ◽  
Vol 108 (Supplement_2) ◽  
Author(s):  
C Lewis-Lloyd ◽  
J Dubern ◽  
K Kalenderski ◽  
N Halliday ◽  
M Alexander ◽  
...  
Keyword(s):  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Bacterial Cells ◽  
Urinary Catheters ◽  
Elective Colorectal Surgery ◽  
Mineral Compositions ◽  
Microscopy Data ◽  
Tract Infections ◽  
Biofilm Development ◽  
Hospital Acquired

Abstract Introduction Catheter associated urinary tract infections account for 40% of hospital acquired infections. They are associated with biofilms consisting of bacterial cells enmeshed in a self-generated extracellular matrix adhering to catheter surfaces. We have developed a novel polymer family that, coated onto urinary catheters, creates a “non-stick” surface preventing biofilm development. Method Prospective cohort of elective colorectal patients recruited pre-operatively, received a standard silicone (SS) or Camstent (BACTIGON®) coated urinary catheter. After removal, catheters were cut longitudinally into 3 segments. Biomass and biomineralisation were analysed using confocal fluorescence microscopy. Data were normalised by square rooting the catheter indwelling duration. Environmental scanning electron microscopy and energy dispersive x-ray spectroscopy was performed. Results Of 40 patients, 20 each received a SS or coated catheter. Between SS and coated catheters, average indwelling duration was similar and biofilm biomass was 32.068µg/cm2 (95%CI ±21.950) vs. 1.948µg/cm2 (95%CI ±2.595) (P = 0.0111). Confocal microscopy suggested a 93.93% reduction in biofilm biomass on coated catheters. Mineral compositions were different with biofilm and struvite/apatite on SS and calcium oxalate, endogenously derived, on coated catheters. Conclusions Inert BACTIGON® coated catheters appear superior at preventing biofilm formation than SS catheters. Clinical trials are needed to determine the clinical and health economic benefit of this intervention.

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