Aging of Silastic Peritoneal Catheters

1991 ◽  
Vol 14 (12) ◽  
pp. 765-770 ◽  
Author(s):  
P. Poisetti ◽  
G. Bergonzi ◽  
S. Ballocchi ◽  
F. Fontana ◽  
L. Scarpioni
Keyword(s):  
Electron Microscopy ◽  
External Surface ◽  
Chemical Properties ◽  
Internal Surface ◽  
Barium Sulphate ◽  
Oxidation Peak ◽  
Physico Chemical ◽  
Abdominal Portion ◽  
Scanning Electron

Increasing the survival of patients on CAPD is related to the long-term reliability of the peritoneal access. Six silicone Tenckhoff catheters (with strip or diffuse barium sulphate inclusion) removed after 39-69 months because of the appearance of external segment fissures, were analysed by scanning electron microscopy (SEM) and infrared spectroscopy with attenuated total refractance (ATR). The extracorporeal portion of the catheters showed (by ATR) a more prominent oxidation peak on the external than the internal surface; SEM showed marks and cracks on the external surface and exfoliation and flattening of the silastic reticle on the intraluminal surface. No evidence of oxidation was found in the intra-abdominal portion of the catheters but biofilm was found. We suggest that barium sulphate may render the silastic brittle and physiological and environmental long-term factors (such as uv-rays, temperature, sweat and disinfectants) could cause oxidation and loss of physico-chemical properties, with critical aging of the silastic and loss of catheter resistance to mechanical injury.

scholarly journals Failure of Heat Exchanger Return Bend Due to Long-Term Localized Overheating [Kerusakan pada Pipa Belokan U Alat Penukar Kalor akibat Panas Berlebih secara Lokal dalam Jangka Panjang]

Metalurgi ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 19
Author(s):  
Dewa Nyoman Adnyana
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Heat Exchanger ◽  
Energy Dispersive Spectroscopy ◽  
External Surface ◽  
Hot Spot ◽  
Energy Dispersive ◽  
Metallographic Examination ◽  
Scanning Electron

A return bend of a heat exchanger had failed due to bursting after it had been only about 2.5 years in service. The heat exchanger was used to transfer heat from hot combustion gas on the shell side to the feedstock oil on the tube side. Type and factors that may have caused the return bend bursting are discussed in this paper. The metallurgical assessment was conducted by preparing a number of specimens from the as-received burst and unburst return bends. Various laboratory examinations were performed including visual and macroscopic examination, chemical analysis, metallographic examination, hardness testing, and scanning electron microscopy equipped with energy-dispersive spectroscopy analysis. Results of the metallurgical assessment obtained showed that the burst return bend had been experiencing fracture overload due to local hot spot or long-term localized overheating occurred on the outer bend external surface. The long-term localized overheating was most likely caused by formation of fouling deposit that was built up on the outer bend internal surface, leading to increase the corrosion rate significantly and resulted in excessive metal loss or thinning occurred on the outer bend external surface. Consequently, the hoop stress at the outer bend section had been increasing significantly and eventually the working pressure of the feedstock oil on the tube side could burst the return bend wall thereonAbstrakTulisan ini menyajikan penelitian yang dilakukan pada sebuah belokan pipa U (return bend) pada sebuah alat  penukar kalor yang mengalami kerusakan (pecah) setelah beroperasi hanya dalam waktu 2,5 tahun. Alat penukar kalor tersebut digunakan untuk memindahkan panas dari gas panas hasil pembakaran pada sisi bejana/tabung ke  dalam bahan baku minyak (feedstock oil) pada sisi pipa. Material belokan pipa U tersebut dibuat dari baja karbon dengan standar ASTM A-234 Gr.WPB, memiliki diameter 2 inch dan tebal SCH 80. Penelitian berupa observasi dan pengujian metalurgi dilaksanakan dengan menyiapkan sejumlah sampel material dari belokan pipa U, baik yang sudah pecah maupun yang tidak pecah. Pengujian yang dilakukan meliputi uji visual dan makro, analisa kimia, uji metalografi, uji kekerasan dengan metoda Vickers dan SEM (scanning electron microscopy) - EDS (energy dispersive spectroscopy).  Hasil pengujian metalurgi menunjukkan bahwa pipa belokan U yang pecah mengalami kerusakan akibat beban berlebih yang dipengaruhi oleh local hot spot atau panas berlebih secara lokal dalam jangka panjang (long-term localized overheating). Akibatnya, tegangan yang bekerja pada dinding belokan pipa U mengalami peningkatan yang sangat signifikan sehingga pada akhirnya tekanan operasi yang terjadi pada bahan  baku minyak di dalam  pipa dapat merobek atau memecahkan bagian dinding belokan pipa U tersebut.

Chemical Composition and Functional Characteristics of Dietary Fibers from Pingguoli Pear (Pyrus Bretschneideri Rehd. cv. Pingguoli Pear)

2018 ◽  
Vol 18 (1) ◽  
pp. 39-45
Author(s):  
Li Liang ◽  
Wang Tie-qiao ◽  
Xue Bei ◽  
Liu Zhen-dong ◽  
Zou Lan
Keyword(s):  
Electron Microscopy ◽  
Galacturonic Acid ◽  
Glucuronic Acid ◽  
Structural Characteristics ◽  
Chemical Properties ◽  
Principal Component ◽  
Dietary Fibers ◽  
Physico Chemical ◽  
Scanning Electron

In this study, apple–pear pomace dietary fibers were treated with acid, alkali, cellulase, and hemicellulase. The effects of these treatments on the chemical constitutions, structural characteristics, functional properties, and the quality of apple–pear pomace dietary fibers were investigated. The results showed that the purity of apple–pear pomace dietary fibers was 79–83%, and the fiber contained cellulose, hemicellulose, pectin, and lignin. Their monosaccharide structures included mannose, glucosamine, ribose, rhamnose, glucuronic acid, galacturonic acid, galactosamine, glucose, galactose, xylose, arabinose, and fucose. The scanning electron microscopy showed that all the apple–pear pomace dietary fibers were beehive shaped, but their functional and physico-chemical properties were different. Using the main constituents and the functional and physico-chemical properties as indicators, through a principal component analysis, we determined the main constituents and characteristics of four apple–pear pomace dietary fibers.

The Analysis of Morphology Characteristics of Iron Plaque on the Roots of Carex cinerascens

2014 ◽  
Vol 675-677 ◽  
pp. 140-144
Author(s):  
Chun Ying Liu ◽  
Xiao Feng Gong ◽  
Ju Yun Yang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Properties ◽  
Amorphous Coating ◽  
X Ray ◽  
Eds Analysis ◽  
Physico Chemical ◽  
Root Surfaces ◽  
Morphology Characteristics ◽  
Scanning Electron

The physico-chemical properties of iron plaques formed on the root surfaces ofCmarex cinerascensunder laboratory conditions were determined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectrometry (EDS) analysis. Iron plaques were present as an amorphous coating on root surfaces with an uneven distribution. EDS analysis showed that iron plaques were composed of Fe , Si, Al and lesser amounts of Ca in plaqued root surfaces.

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

1971 ◽  
Vol 29 ◽  
pp. 410-411 ◽  
Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Osmium Tetroxide ◽  
External Surface ◽  
Three Dimensional ◽  
Surface Structures ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

Scanning Electron Microscopic and Electrophoretic Observations on Barium Sulphate Used to Adsorb Clotting Factors

1975 ◽  
Vol 33 (02) ◽  
pp. 256-270
Author(s):  
R. M Howell ◽  
S. L. M Deacon
Keyword(s):  
Electron Microscopy ◽  
Factor Xa ◽  
Barium Sulphate ◽  
High Density ◽  
Low Density ◽  
Factor X ◽  
Clotting Factors ◽  
Electron Microscopic ◽  
Complementary Techniques ◽  
Scanning Electron

SummaryElectron microscopy and particle electrophoresis were found to be complementary techniques with which to complete the physical data from an earlier study on barium sulphates used to adsorb clotting factors from serum. The differences revealed by scanning electron microscopy (S. E. M.) in the physical shape of low and high density grades of barium sulphate particles appear to be of greater significance than charge as expressed by electrophoretic mobility, in determining whether or not precursor or preformed factor Xa is eluted.This conclusion was based on the finding that at pH values close to 7, where the adsorption from serum occurs, all samples with the exception of natural barytes were uncharged. However as the high-density, or soil-grade, was found by S. E. M. to consist of large solid crystals it was suggested that this shape might induce activation of factor X as a result of partial denaturation and consequent unfolding of the adsorbed protein. In contrast, uptake of protein into the centre of the porous aggregates revealed by S. E. M. pictures of low-density or X-ray grade barium sulphate may afford protection against denaturation and exposure of the enzyme site.The porous nature of particles of low-density barium sulphate compared with the solid crystalline forms of other grades accounts not only for its lower bulk density but also for its greater surface/gram ratio which is reflected by an ability to adsorb more protein from serum.Neither technique produced evidence from any of the samples to indicate the presence of stabilising agents sometimes used to coat particles in barium meals.

scholarly journals Preparation and Characterization of PEBAX-5513/AgBF4/BMIMBF4 Membranes for Olefin/Paraffin Separation

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1550 ◽  
Author(s):  
So Young Kim ◽  
Younghyun Cho ◽  
Sang Wook Kang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Poor Performance ◽  
Amide Group ◽  
Stabilizing Effect ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Scanning Electron

In this study, we investigated a poly(ether-block-amide)-5513 (PEBAX-5513)/AgBF4/1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) composite membrane, which is expected to have a high stabilizing effect on the Ag+ ions functioning as olefin carriers in the amide group. Poly(ethylene oxide) (PEO) only consists of ether regions, whereas the PEBAX-5513 copolymer contains both ether and amide regions. However, given the brittle nature of the amide, the penetration of BMIMBF4 remains challenging. The nanoparticles did not stabilize after their formation in the long-term test, thereby resulting in a poor performance compared to previous experiments using PEO as the polymer (selectivity 3; permeance 12.3 GPU). The properties of the functional groups in the polymers were assessed using Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis, which confirmed that the properties endowed during the production of the film using the ionic liquid can impact the performance.

scholarly journals Optimization of Innovative Three-Dimensionally-Structured Hybrid Vesicles to Improve the Cutaneous Delivery of Clotrimazole for the Treatment of Topical Candidiasis

Pharmaceutics ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 263 ◽  
Author(s):  
Maria Letizia Manca ◽  
Iris Usach ◽  
José Esteban Peris ◽  
Antonella Ibba ◽  
Germano Orrù ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Yeast Cells ◽  
Unilamellar Vesicles ◽  
Transmission Electron ◽  
Physico Chemical

New three-dimensionally-structured hybrid phospholipid vesicles, able to load clotrimazole in a high amount (10 mg/mL), were obtained for the first time in this work by significantly reducing the amount of water (≤10%), which was replaced with a mixture of glycerol and ethanol (≈90%). A pre-formulation study was carried out to evaluate the effect of both the composition of the hydrating medium and the concentration of the phospholipid on the physico-chemical properties of hybrid vesicles. Four different three-dimensionally-structured hybrid vesicles were selected as ideal systems for the topical application of clotrimazole. An extensive physico-chemical characterization performed using transmission electron microscopy (TEM), cryogenic transmission electron microscopy (cryo-TEM), 31P-NMR, and small-angle X-ray scattering (SAXS) displayed the formation of small, multi-, and unilamellar vesicles very close to each other, and was capable of forming a three-dimensional network, which stabilized the dispersion. Additionally, the dilution of the dispersion with water reduced the interactions between vesicles, leading to the formation of single unilamellar vesicles. The evaluation of the in vitro percutaneous delivery of clotrimazole showed an improved drug deposition in the skin strata provided by the three-dimensionally-structured vesicles with respect to the commercial cream (Canesten®) used as a reference. Hybrid vesicles were highly biocompatible and showed a significant antifungal activity in vitro, greater than the commercial cream Canesten®. The antimycotic efficacy of formulations was confirmed by the reduced proliferation of the yeast cells at the site of infection in vivo. In light of these results, clotrimazole-loaded, three-dimensionally-structured hybrid vesicles appear to be one of the most innovative and promising formulations for the treatment of candidiasis infections.

Failure Analysis of High Pressure Container using Fractography and Material Morphology

2018 ◽  
Vol 773 ◽  
pp. 287-291
Author(s):  
Eui Soo Kim
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Failure Analysis ◽  
Large Scale ◽  
Chemical Properties ◽  
Accurate Analysis ◽  
Internal Pressures ◽  
Scanning Electron ◽  
And Chemical Properties

High-pressure gas containers must be able to withstand high internal pressures because they store compressed gases. Otherwise, cracks or defects may lead to an explosion, which may in turn lead to a large-scale disaster. Therefore, accurate analysis of the causes of cracks or defects and various techniques for detecting cracks or defects are needed. In this research, we analyzed the failure mechanism of a high-pressure gas container through fractography using scanning electron microscopy and optical microscopy and through measurements of their mechanical and chemical properties.

scholarly journals New crosslinkers for electrospun chitosan fibre mats. I. Chemical analysis

2012 ◽  
Vol 9 (75) ◽  
pp. 2551-2562 ◽  
Author(s):  
Marjorie S. Austero ◽  
Amalie E. Donius ◽  
Ulrike G. K. Wegst ◽  
Caroline L. Schauer
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Mechanical Stability ◽  
Dissolution Tests ◽  
Natural Polysaccharide ◽  
Biomedical Field ◽  
The Stability ◽  
Scanning Electron

Chitosan (CS), the deacetylated form of chitin, the second most abundant, natural polysaccharide, is attractive for applications in the biomedical field because of its biocompatibility and resorption rates, which are higher than chitin. Crosslinking improves chemical and mechanical stability of CS. Here, we report the successful utilization of a new set of crosslinkers for electrospun CS. Genipin, hexamethylene-1,6-diaminocarboxysulphonate (HDACS) and epichlorohydrin (ECH) have not been previously explored for crosslinking of electrospun CS. In this first part of a two-part publication, we report the morphology, determined by field emission scanning electron microscopy (FESEM), and chemical interactions, determined by Fourier transform infrared microscopy, respectively. FESEM revealed that CS could successfully be electrospun from trifluoroacetic acid with genipin, HDACS and ECH added to the solution. Diameters were 267 ± 199 nm, 644 ± 359 nm and 896 ± 435 nm for CS–genipin, CS–HDACS and CS–ECH, respectively. Short- (15 min) and long-term (72 h) dissolution tests (T 600 ) were performed in acidic, neutral and basic pHs (3, 7 and 12). Post-spinning activation by heat and base to enhance crosslinking of CS–HDACS and CS–ECH decreased the fibre diameters and improved the stability. In the second part of this publication, we report the mechanical properties of the fibres.

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