scholarly journals Biosorption of Cr(III) and Pb(II) by Schoenoplectus californicus and Insights into the Binding Mechanism

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Tomás Agustín Rearte ◽  
Patricia Beatriz Bozzano ◽  
Maria Luisa Andrade ◽  
Alicia Fabrizio de Iorio
Keyword(s):  
Energy Dispersive Spectrometry ◽  
Environmental Scanning Electron Microscopy ◽  
Isotherm Models ◽  
Environmental Scanning ◽  
Schoenoplectus Californicus ◽  
Sorption Equilibrium ◽  
Before And After ◽  
Sorption Mechanisms ◽  
Economical Alternative ◽  
Extracting Agents

Biosorption and desorption of chromium and lead on shoots biomass of Schoenoplectus californicus were investigated by performing batch sorption tests in different conditions of pH, biosorbent dose, and initial concentration in simple and binary solutions. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were employed to describe sorption equilibrium. Filters and biomass were characterized before and after treatments by environmental scanning electron microscopy and X-ray energy-dispersive spectrometry. The optimal conditions for biosorption were found to be pH 5 for both metals. The contact time to reach pseudoequilibrium changed as a function of pH and the metal studied. The highest optimisation of biosorbent dose was 5 g L−1 at pH 7 and 15 g L−1 at pH 5 for both metals. The most effective extracting agents for lead and chromium proved to be HNO3 and NaOH, respectively. The recovery of lead was greater than of chromium because the Cr(III) sorption mechanisms involve a stronger binding energy than the mechanisms for Pb(II), such as in intern sphere complexes. Both metals accounted for a high % removal (>90%) under the best sorption conditions. The use of Schoenoplectus californicus proved to be an efficient and economical alternative for the treatment of effluents contaminated with lead and chromium.

scholarly journals Effect of Alkaline Degumming on Structure and Properties of Lotus Fibers at Different Growth Period

2015 ◽  
Vol 10 (1) ◽  
pp. 155892501501000 ◽  
Author(s):  
Fengyan Li ◽  
Hongjun Fu
Keyword(s):  
Environmental Scanning Electron Microscopy ◽  
Growth Period ◽  
Bond Rupture ◽  
Environmental Scanning ◽  
Structure And Properties ◽  
Breaking Force ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
Before And After

Lotus fibers are pulled from different period of lotus root. Alkaline was used as degumming agent to remove non-cellulose impurities of lotus fibers. Environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD) and FTIR were used to characterize surface morphology and microscopic structure of lotus fibers before and after degumming. The effect of alkaline degumming on tensile properties of lotus fibers is investigated. The results show that impurities remove, hydrogen bond rupture, and crystallinity of partly armorphous chain occur during alkaline degumming. All of these changes play roles in influencing fiber tensile breaking force and elongation at break.

scholarly journals Demineralization, Collagen Modification and Remineralization Degree of Human Dentin after EDTA and Citric Acid Treatments

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 25 ◽  
Author(s):  
Maria Gandolfi ◽  
Paola Taddei ◽  
Anna Pondrelli ◽  
Fausto Zamparini ◽  
Carlo Prati ◽  
...  
Keyword(s):  
Citric Acid ◽  
Ethylenediaminetetraacetic Acid ◽  
Environmental Scanning Electron Microscopy ◽  
Chelating Agent ◽  
Environmental Scanning ◽  
X Ray ◽  
Before And After ◽  
Human Dentin ◽  
Mineral Components ◽  
Mineralization Degree

The aim of the study was to investigate the effects of several decalcifying agents used as irrigant solutions in endodontic treatment on collagen and mineral components of dentin. Coronal dentin discs from five caries-free human third molars with a smear layer were treated for one minute with a chelating solution (1% Ethylenediaminetetraacetic acid (EDTA), 10% EDTA, 17% EDTA, 10% citric acid). Mineralization degree (Ca/N and P/N atomic ratios, IR Iapatite/Iamide II and I1410(carbonate)/I554(phosphate) spectroscopic ratios) and possible collagen rearrangements (collagen infrared (IR) amide II e III shifts) were evaluated by environmental scanning electron microscopy (ESEM)/energy dispersive X-ray spectroscopy (EDX) and IR spectroscopy before and after treatment (T0) and after ageing (T24h and T2m) in simulated body fluid (SBF). At T0, analysis showed that the highest demineralizing effect was achieved using a 10% citric acid solution and 10% EDTA, while the smallest effect was observed when using 17% EDTA. No significant collagen modifications were detected upon treatment with 1% EDTA, while subtle changes were observed after the other treatments. At T24h or T2m, analyses showed the highest remineralization values for 1% EDTA and the lowest for 10% citric acid, mainly at T2m. The samples treated with 17% EDTA showed slight collagen rearrangements upon remineralization. In conclusion, the highest demineralizing effect was observed for 10% EDTA and 10% citric acid. Collagen rearrangement was found for all the treatments except for 1% EDTA. The highest remineralization capability in SBF values was recorded for 1% EDTA and the lowest for 10% citric acid. A slight collagen rearrangement upon remineralization was still present in 17% EDTA-treated samples. Clinical use as a chelating agent in the endodontic therapy of citric acid and concentrated EDTA solutions should be reconsidered.

Physical and performance characteristics of nonwoven aviation wipers composed of various staple fibers including raw cotton

2018 ◽  
Vol 49 (9) ◽  
pp. 1198-1217
Author(s):  
Rebecca J Hron ◽  
Doug J Hinchliffe ◽  
Michael S Cintrón ◽  
Terri Von Hoven ◽  
Crista A Madison ◽  
...  
Keyword(s):  
Tensile Testing ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Silicone Grease ◽  
Aviation Maintenance ◽  
Nonwoven Materials ◽  
Cotton Sample ◽  
Before And After ◽  
Hexane Extracts ◽  
And Performance

Several nonwoven materials were evaluated as candidates for wipe fabrics intended for sensitive applications, namely aviation maintenance. Wipes designed for this purpose must conform to specific guidelines delineated by the appropriate governing bodies. Fabric selections included both synthetic and natural staple fibers such as polyester, Lyocell and raw cotton varieties. A thorough evaluation of extractable material in an array of solvents revealed that cotton-based nonwovens as well as Lyocell have some of the lowest percentages of leachable solids. The resistance of these fabrics to abrasion and the damage incurred by them was also studied. Environmental scanning electron microscopy taken before and after the linting procedure showed that the greige cotton sample demonstrated some of the least damage. Fourier-transform infrared spectroscopy examinations of hexane extracts confirmed the absence of any silicone grease contamination on the wipes materials. Standardized tensile testing indicated that the cotton samples, especially mechanically cleaned greige cotton, have robust tensile properties that are important characteristics for wiping materials. These results indicate that cotton nonwovens, particularly greige cotton, are promising candidates for the development of future aviation and other wipes materials.

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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