Scanning Electron Microscopic Appearance Research Articles

Optimisation of Ultra-High-Performance Concrete with Special Quarry Dust

The cement composition of concrete directly affects the CO2emissions to the environment. UHPC (Ultra High-Performance Concrete) is a new type of concrete rapidly gaining popularity in the building industry due to its superior strength and endurance. In contrast to regular concrete, UHPC requires more than twice as much cement, making it more expensive and leaving a more significant carbon imprint. In this study, waste cement was substituted with 4%, 8%, and 12% special quarry dust from a manufacturer in Kuantan, Malaysia. Maximum compressive strength and quarry dust percentage are determined through experimentation and assessed in Design Expert Software. This investigation tested modified UHPC for strength, durability, and scanning electron microscope (SEM)appearance. Experiments show that substituting 21% quarry dust for cement yields the best outcomes. Since the particle size of quarry dust is finer than that of other matrices, it helps to reduce voids and boosts the UHPC's endurances. The quarry dust adds filler and a minor increase in viscosity to the UHPC, which is a better replacement for anhydrate cement in filler applications.

Microstructure, mechanical performance and corrosion properties of base metal solder joints

Alloys have been considered to be of paramount importance in the field of prosthodontics. Long span prosthesis may often require joining of one or more individual castings to obtain better fit, occlusal harmony and esthetics in comparison to one-piece casting. This study was undertaken to evaluate the mechanical properties of base metal alloys joined by two different techniques, namely, gas oxygen torch soldering and laser fusion, compared to a one-piece casting. Mechanical properties evaluated were tensile strength, percentage of elongation and hardness of the solder joint. In addition, corrosion properties and scanning electron microscopic appearance of the joints were also evaluated. The samples were prepared according to American Society for Testing Materials specifications (ASTM, E8). Specimens were made with self-cure acrylic and then invested in phosphate-bonded investment material. Casting was done in induction casting machine. Thirty specimens were thus prepared for each group and compared with 30 specimens of the one-piece casting group. SPSS software (version 10.0, Chicago, IL, USA) was used for statistical analysis. ANOVA and Benferroni post hoc tests were done for multiple comparisons between the groups and within the groups for mean difference and standard error. Results showed that tensile strength of the one-piece casting was higher than laser fused and gas oxygen torch soldered joints. Laser fused joints exhibited higher hardness values compared to that of gas oxygen torch soldered joints. Scanning electron microscopic examination revealed greater porosity in the gas oxygen torch soldered joints. This contributed to the reduction in the strength of the joint. Gas oxygen torch soldered joints showed less corrosion resistance when compared to laser fused joints and one-piece casting. Laser fusion, which is a recent introduction to the field of prosthodontics, produces joints which have properties between those of one-piece casting and the gas oxygen torch soldering.

Fadengranulome mit Kalziumpyrophosphat-Ablagerungen

In the report two foreign body granulomas, one observed in the fibrous periarticular tissue and the other one in tendo achilles with depositions of crystals inside the granulomas are described. Polarisation microscopy exhibited birefringent crystals which stained black with the van Kossa reaction. The scanning electron microscopic appearance was that of calcium-pyrophosphate-dihydrate when compared with crystals of menisceal tissue in "chondrocalcinosis". The structure of the crystals was different from those that can be observed in calcifying tendinitis or in calcified scars. By X-ray microanalysis nearly identical peaks for calcium and phosphorus were measured, indicating the atomic composition of calcium-pyrophosphate-dihydrate. For the crystalline deposits were restricted to an acellular tissue between the foreign body material it is concluded that necroses in the fibrous periarticular tissues or tendons may be prone for deposition of calcium-pyrophosphate.

Scanning electron microscopy of the normal epidermis and the epidermis in vitro.

SUMMARY A simplified technique has been used to examine the epidermis in five skin biopsies and in eight cultured skin specimens by scanning electron microscopy. Paraffin or cryostat sections of the tissue were cut and prepared according to routine histological methods and then given an electrically conducting coating before examination in the scanning electron microscope. The epidermis was easily identified and a particularly good view was obtained of intercellular bridges at high magnifications. Intra-epidermal and basal layer dendritic cells were also easily located and their relationships to surrounding keratinocytes by long intercellular processes are described. The scanning electron microscopic appearance of epidermal cells in cultured explains of skin showed a strong resemblance to other cells and tissues in culture and also demonstrated the presence of a unicellular or subcellular membrane at the leading edge similar in appearance to the undulating membrane of fibroblasts in culture. It is stressed that the method is of particular use in the examination of intercellular relationships within the epidermis and in the inspection of histological material at higher magnifications than are possible by light microscopy.

Effect of bleaching agents on bonding to pulp chamber dentine

To determine the effect of intracoronal bleaching agents on adhesion of bonding agents to pulp chamber dentine. Forty extracted human maxillary anterior teeth were randomly divided into four groups of 10 teeth each. Bleaching agents were sealed in pulp chambers for 7 days, as in clinical use. Group 1 (control): distilled water, group 2: 35% hydrogen peroxide, group 3: sodium perborate mixed with water, and group 4: sodium perborate mixed with 35% hydrogen peroxide. Teeth were stored in saline at 37 degrees C for 7 days. After the bleaching agent was removed, teeth were leached in water for a further 7 days prior to bonding. The crown was cut vertically from mesial to distal and the labial pulp chamber dentine was prepared for bonding with Clearfil SE-Bond and filled with resin composite (Clearfil AP-X). The bonded specimens were kept moist at 37 degrees C for 24 h. Microtensile bond strengths were determined using a universal testing machine. Additional teeth were prepared using the same bleaching procedures to investigate the scanning electron microscopic appearance of the dentine surface. Mean values (+/-SD) of microtensile bond strength for the experimental groups were: group 1: 5.29 +/- 2.21 MPa, group 2: 5.99 +/- 1.51 MPa, group 3: 9.17 +/- 1.65 MPa and group 4: 3.99 +/- 1.31 MPa. Dentine treated with sodium perborate in water (group 3) had significantly higher mean bond strength when compared with the other three groups (P < 0.05, Tukey's test). Mean bond strength was lowest when dentine was treated with sodium perborate plus hydrogen peroxide (group 4). In terms of subsequent bond strength during restoration, sodium perborate mixed with distilled water appears to be the best intracoronal bleaching agent.

Elastic properties and scanning electron microscopic appearance of manual continuous curvilinear capsulorhexis and vitrectorhexis in an animal model of pediatric cataract

Purpose: To compare the tear resistance of anterior capsulotomies using manual continuous curvilinear capsulorhexis (CCC) and vitrector-cut capsulotomy (vitrectorhexis) techniques in an animal model of the pediatric eye and in 2 pairs of human infant eyes. Setting: Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Methods: Continuous curvilinear capsulorhexis and automated vitrectorhexis capsulotomy techniques were performed in 20 pig eyes, 10 with each technique. The capsules were then stretched until they ruptured. The forces required for rupture after each technique were compared. The forces required for rupture of the pig eye lens capsule were also compared with those required for the human infant eye lens capsule. Scanning electron microscopy was performed in each group following intraocular lens (IOL) insertion. Results: All capsules stretched adequately for IOL insertion. The percentage ofstretch prior to rupture was higher in the capsulorhexis group (mean 157%, range 147% to 169%) than in the vitrectorhexis group (mean 135%, range 124% to 147%) ( P < .001). The percentage of stretch in the human infant eyes was not statistically different from that in the porcine eyes ( P > .05). Conclusions: The manual CCC offered greater resistance to capsule tearing than the vitrectorhexis and also revealed a more smooth, regular edge. It therefore remains the gold standard. However, the vitrectorhexis displayed more than adequate resistance to unwanted anterior capsule tears when used for IOL insertion through capsulotomy sizes currently used in clinical practice.

Effects of exogenous superoxide anion and nitric oxide on the scavenging function and electron microscopic appearance of the sinusoidal endothelium in the isolated, perfused rat liver

Background/Aims: Functional and morphological alterations of the hepatic sinusoidal endothelial cell occur in several models of experimental liver injury and in clinical settings. The causes of these alterations are multiple. The aim of this study was to test the hypothesis that the early functional impairment and morphological alterations of the sinusoidal endothelial cell and hepatic sinusoid associated with liver injury are mediated by free radical species, such as superoxide anion and nitric oxide.Methods: Isolated rat livers were perfused by recirculation with hemoglobin-free, Krebs-Henseleit bicarbonate buffer and presented with a source of superoxide anion (xanthine oxidase+hypoxanthine) or nitric oxide (S-nitroso-N-acetyl penicillamine). Hyaluronan uptake (an index of sinusoidal endothelial cell scavenging function), thiobarbituric acid-reactive substances content of the tissue (a marker of lipid peroxidation), reduced and oxidized glutathione (a marker of the thiol system oxidation/reduction state), lactate dehydrogenase and alanine aminotransferase activities (markers of cytolysis), as well as scanning and transmission electron microscopic appearance of the sinusoid were evaluated.Results: At the high concentrations used, both free radical generating systems suppressed hyaluronan uptake, increased malondialdehyde content of the tissue, enhanced the release of both liver enzymes, decreased the total glutathione content of the liver, and altered the ratio of reduced/oxidized glutathione. Both free radical species induced dose-dependent morphological alterations of the sinusoid, consisting of the appearance of large gaps replacing the sieve-plated fenestration.Conclusions: The free radical species-induced functional impairment and morphological alterations of the liver sinusoid, presented in this study, closely resemble the early in vivo changes associated with liver injury under a variety of conditions, such as preservation and reperfusion, or administration of hepatotoxicants such as D-galactosamine, Gram-negative bacterial lipopolysaccharides, acetaminophen, alcohol and others. Therefore, we suggest that early liver sinusoid injury, observed under these conditions, can be attributed to the action of free radicals, such as superoxide anion and nitric oxide.

Gross, histological and scanning electron microscopic appearance of dorsal fin rot in farmed Atlantic salmon, Salmo salar L., parr

AbstractThe gross, histological and scanning electron microscopic appearance of dorsal fin rot in farmed Atlantic salmon parr, Salmo salar L. is described. The lesions were grouped into seven categories: (1) peripheral erosion and ray splitting; (2) peripheral erosion with some nodularity; (3) severe nodularity with differing degrees of tissue loss; (4) extensive to total loss of the dorsal fin; (5) smooth thickening of the dorsal fin; (6) haemorrhagic dorsal fin lesions; and (7) healed dorsal fin rot lesions. The main sign of injury was clefts extending through the epithelium. These injuries were consistent with bites from other parr. During healing from such wounds, damaged cells sloughed from the surface, and there was swelling and hyperplasia in the remaining cells. The majority of the thickening in the fins was the result of epithelial hyperplasia with a variable cellular inflammatory response. The distal epithelium of fins with severe fin rot (i.e. nodular and eroded) was rough, irregular and swollen with superficial nodular extensions. Wounds in all stages of repair were more numerous in such areas. Fin rays were frequently observed protruding from the abnormal epithelium at the distal edge of the fin. With the exception of the isolation of Aeromonas salmonicida from a small number of cases, no significant bacterial involvement was detected. Under scanning electron microscopy, bacteria were only detected on the exposed fin rays and not in association with the abnormal epithelium. In the majority of cases, the dorsal fin was either the only fin damaged or the most severely damaged. It is suggested that the hyperplastic response to numerous bite wounds is responsible for the accumulation of abnormal epithelium typical of dorsal fin rot in farmed Atlantic salmon parr.

Effects of interleukin-1β on scanning electron microscopic appearance and thyroid peroxidase content of human thyrocytes in monolayer culture

Interleukin (IL-1), an inflammatory cytokine that is detected in the thyroid tissues of patients with autoimmune thyroiditis, is believed to be involved in the disease process. To clarify the role of IL-1 in the development of autoimmune thyroiditis, we investigated the effects of interleukin-1β (IL-1β) on the morphology of human thyrocytes in monolayer culture as well as the effect on thyroid peroxidase (TPO) content of these cells. Human normal thyrocytes were cultured with IL-1β for 4 days in the presence and absence of TSH. In morphologic studies, cultured cells were fixed for examination by scanning electron microscopy and for immunofluorescent staining of actin filaments. IL-1 produced striking morphologic changes in the cultured thyrocytes, including the cytoplasmic retraction and dissociation and/or depolymerization of actin filaments. These changes were unrelated to TSH stimulation. For detection of TPO, cultured cells were stained by an immunofluorescent technique and analyzed by fluorescence photometry. IL-1 reduced the TPO content and inhibited the TSH-induced increase in TPO in a concentration-dependent manner. These morphological changes and the reduction in TPO content of cultured thyrocytes suggest that IL-1 modulates the pathophysiology of autoimmune thyroiditis.

Structural and functional changes in root dentin following exposure to KTP/532 laser

The use of a new, modified Nd:YAG laser called the KTP/532 laser was evaluated within root canals to determine whether it would modify dentin permeability or alter the scanning electron microscopic appearance of canal dentin. Energies and exposure times were chosen which did not permit periodontal temperatures to increase above 5 degrees C (1 W x 1 s-5 W x 0.5 s). Half of the root canals were covered with smear layer and half were treated with EDTA/NaOCI to remove the smear layer. The results showed that this laser did not change the permeability of the smear layer-covered dentin, although scanning electron microscopic examination revealed modifications to the surface of smear layer. Lasing of etched dentin produced modest increases in root permeability which were associated with enlargement and cracking of tubule orifices.

In search of the “perfect” anastomosis

Forty-five end-to-side microvascular anastomoses were completed in rat carotid arteries of 0.7-0.8 mm diameter (anastomosing the distal end of the left common carotid to the side of the right common carotid). For comparison both 10-0 and 11-0 sutures were utilized in different anastomotic techniques: interrupted, direct-continuous, and diagonal-continuous sutures, plus total mural thickness vs. partial mural thickness (piercing only the adventitia and outer media, excluding the intima). Anastomoses were evaluated for patency and scanning electron microscopic appearance after 10 to 12 weeks. The results indicate complete patency in all anastomoses. Ultrastructural observations revealed nearly normal intimal appearance in the partial medial technique and only minimal evidence of intimal injury in the other techniques. It is concluded that 100% patency can be obtained regardless of suture size or anastomotic technique. The most important factor in anastomotic patency is the operator's technical skill.

Macroscopic and scanning electron microscopic appearance and hardness values of developmental defects in human permanent tooth enamel.

Defects present in 12 human permanent teeth were classified on the basis of their macroscopic appearance as hypoplasia (three teeth), diffuse opacities (three teeth), white demarcated opacities (one tooth but two defects), or yellow demarcated opacities (five teeth but six defects). The hardness values and SEM appearance of the defective enamel were determined after the teeth were sectioned through the lesion(s) and were distinctive for each type of defect. The thin enamel of the hypoplastic lesions was either opaque (with reduced hardness values) or translucent (with near-normal hardness values and sometimes a change in prism orientation external to an incremental line). The enamel of the diffuse and demarcated opacities was of normal thickness. The changes in the macroscopic and SEM appearance, and the reduced hardness values of the diffuse patchy opacities, were restricted to the outer 150 microns of the enamel. The demarcated opacities varied in position and depth, and in places had a clearly marked boundary with the adjacent normal enamel. Hardness values were related to color change, with yellow lesions being softer than white. Although prism direction was normal within demarcated opacities, prism outlines were less distinct. The findings suggest that temporary and permanent dysfunction of ameloblasts can occur in both secretory and maturation phases, influencing the final appearance of the lesion.

Tympanosclerosis: a scanning electron microscopic study.

Twelve specimens of tympanosclerosis were examined. Six were immediately fixed in 3% glutaraldehyde and 6 were obtained from the departmental collection of specimens in wax blocks which had previously been examined by light microscopy. Seven specimens were demineralized. The material was examined macroscopically, by light microscopy and by scanning electron microscopy to a magnification of x25,000. The microstructure of tympanosclerosis is an irregular three-dimensional collagen lattice, enclosing distinct, spherical, mineralized aggregates, housed in lacunar-like spaces. This lattice is continuous with the plaque surface which is an envelope, probably of proteinaceous material. The spherical calcified aggregates were absent from the demineralized specimens. There was no structural difference in the scanning electron microscopic appearances of specimens processed conventionally in 3% glutaraldehyde and those previously embedded in wax.

Scanning electron microscopy of submandibular sialoliths: a preliminary report.

This report compares the scanning electron microscopic appearances of the structures in two sialoliths, one surgically removed, the other naturally exfoliated. The first exhibited the typical structure of a lamellated outer layer with an amorphous core. The core contained a large number of structures resembling calcified filamentous organisms. The second consisted of a similar outer lamella but the core contained crystal-lined spaces, amorphous matrix and an heterogeneous array of crystal shapes: there were no structures resembling organisms.

Scanning Electron Microscope Appearance of the Enamel/Composite/Bracket Areas Using Different Methods of Surface Enamel Treatment, Composite Mix and Bracket Loading

Minimal plaque retention on and around orthodontic brackets is of paramount importance if iatrogenic tooth damage is to be avoided. This study made use of the scanning electron microscope to examine how variations in composite mix and finishing affected the smoothness and adaptation at the bracket, composite, and enamel interfaces. The study indicated that the optimum choice for good composite/enamel adaptation with a smooth composite surface and good composite/bracket adaptation involves the use of an intermediate unfilled resin layer, a paste/liquid mix of composite placed on a bracket which is optimally loaded, and no excess composite removed with an instrument.

Dentinal candidiasis in cancer patients

Two examples of an unusual presentation of oropharyngeal candidiasis in cancer patients are offered. The light and scanning electron microscopic appearances of candidiasis involving the dentin of teeth are described. The potential significance of recognition of this form of candidiasis in cancer patients is discussed.

The macroscopic and scanning electron-microscopic appearance and microhardness of the enamel, and the related histological changes in the enamel organ of erupting sheep incisors resulting from a prolonged low daily dose of fluoride

The hypothesis that diffuse opacities in enamel result from a chronic, mild disturbance to ameloblast activities was tested using fluoride. Three sheep (HF) were dosed orally with 0.5, and 3 (LF) with 0.2 mg fluoride/kg body weight daily for 6 months. A control sheep (C) received no additional fluoride. The 7 sheep were killed at or close to the time of emergence of their permanent central incisors. One tooth from each sheep was sectioned longitudinally. The enamel related to the secretory (S) and maturation (M) phases of ameloblast activity at the start of fluoride dosing was determined from a tetracycline marker. The pattern of mineralization of the outer 150 μm of the cut labial enamel was assessed using microhardness testing. The SEM appearance of the acid-etched outer enamel was compared in S and M zones in 5 teeth. The enamel of the C tooth was translucent. Diffuse opacities, similar in appearance to human fluorosis, were present in all fluoride-treated teeth. Hardness values in the outer 70 μm of the enamel decreased as the fluoride dose increased and, in the HF teeth, were lower in the S zone than in the M zone. Fluoride given during the M phase induced a surface hypomineralization which increased in degree and depth when fluoride was also given during the S phase. The SEM appearance of M and S enamel was similar in 2 LF and 1 HF teeth but, in the other HF tooth, S enamel but not M enamel had a disordered prism structure and loosely-packed crystals in an abnormal organic matrix. Histological examination revealed that ameloblasts remained in only 4 of the 7 teeth and that their regression and the formation of the cementum adjacent only to the labial enamel were progressing abnormally.

Dietary manipulation during experimental colorectal carcinogenesis: a morphological study in the rat.

The effect of the dietary manipulation of fat and fibre on the gross pathological, histopathological and scanning electron microscopic appearances of colonic mucosa was studied before and during experimental carcinogenesis in 232 male Albino Swiss rats. Carcinogen treated animals were given 12 consecutive weekly injections of Azoxymethane in a dose of 10 mg/kg per week. The animals were divided between four dietary groups (1: high fat high fibre, 2: low fat high fibre, 3: high fat low fibre and 4: low fat low fibre). The colorectal morphology was assessed at autopsy using standard histopathological techniques. In addition, scanning electron microscopic studies on selected samples were performed. A scoring system was introduced to allow a more accurate comparison of the surface architectural appearances. The high fat low fibre diet was associated with the greatest risk for macroscopic tumour production and the low fat high fibre diet with the lowest risk. Statistically significant differences between each of the dietary groups were noted with the exception of the comparison for tumour induction between the high fat high fibre and low fat high fibre dietary groups. Histopathological analysis confirmed the inter dietary relationships with respect to the extent of neoplastic change. The scanning electron microscopic study revealed that both dietary manipulation and carcinogen treatment influenced the surface characteristics. Control animals fed diet 2 (low fat high fibre) but not treated with carcinogen, showed the greatest deviation from the normal appearances. Animals treated with carcinogen and fed diet 3 (high fat low fibre) consistently showed the greatest surface abnormalities.

Bonding of Fissure Sealant to Etched Demineralized Enamel (Lesions)

Different aspects of the acid-etching of enamel lesions and subsequent bonding of resins were studied, in particular the measurement of the mineral loss as a result of etching and the structure of (etched) lesions in comparison with sound enamel in relation to bonding of resins. The experiments were performed on artificial lesions produced in an acidified gelatine-gel system. During the etching of enamel lesions less calcium was removed as compared to corresponding sound controls. Nevertheless the thickness of the etch steps for the two types of specimens was about the same. This relatively high resistance of the lesions to acid etching is attributed to the high fluoride content of the lesions. The hardness of the lesions and the sound enamel controls was measured at 15 μm below the surface. These values in both cases showed a decrease with successive etchings. The scanning electron microscopic appearance of the lesions revealed that after 1-min acid etching the surface topography was similar to sound enamel, with a prism pattern apparently suitable for resin tag formation and adhesion. The sealing quality of a lesion by a resin, and the integrity of the resultant bond, was tested by subjecting the specimens to a regimen of thermocy cling between 4 and 75 °C. In all cases the etched lesion turned out to support a successful bond. The study demonstrates that enamel lesions are an acceptable and suitable substrate for resin adhesion provided the enamel surface has been acid-etched.

Scanning electron microscopic appearance of chronic ulcerative colitis with and without dysplasia

This study was conducted to determine whether scanning electron microscopy of colonic mucosal biopsy specimens can help to detect dysplasia in patients with chronic ulcerative colitis. In the first phase of the study, using light microscopy as the standard for the diagnosis, the scanning electron microscopic appearance of specimens from patients with chronic ulcerative colitis and control patients was examined. Descriptive criteria were established to identify normal, atrophic, and dysplastic colonic mucosa. In the second phase, quantitative techniques were used to develop more objective criteria for the diagnosis of dysplasia in ulcerative colitis. Twenty-one coded colonic specimens from 11 patients were sequentially examined by scanning electron microscopy and by light microscopy. The three morphometric analyses performed on the surface epithelial cells were number of cells per unit area, number of microvilli per unit area, and percentage of microvilli with a normal width. The cell count and percentage of microvilli with a normal width were significantly reduced in the seven specimens with colonic dysplasia as compared with nondys-plastic tissues. Scanning electron microscopy may serve as an adjunct to light microscopy in the diagnosis of colonic dysplasia.