Cent Hydrofluoric Acid Research Articles

Seventy Per Cent Hydrofluoric Acid Burns: Delayed Decontamination With Hexafluorine® and Treatment With Calcium Gluconate

This is a case report of decontamination and treatment of a 70% hydrofluoric acid (HF) dermal splash injury. A worker was splashed with 70% HF, sustaining approximately 10% TBSA first- to third-degree chemical skin burns of the face, trunk, and left thigh and leg. Initial decontamination involved water rinsing, removal of contaminated clothing, more water rinsing, topical application of magnesium oxide, and administration of intravenous narcotics for management of severe pain. After a delay of approximately 3 hours, active skin washing with Hexafluorine®, 5 L, was performed, followed by intravenous, intradermal perilesional, and topical inunction administration of calcium gluconate. Pain relief and a cooling sensation were quite prompt after Hexafluorine® decontamination. Surgical debridement and skin grafting of the more severe burns were required. No significant systemic toxicity developed, although this has occurred in previously reported similar concentrated HF dermal splash exposure cases, some of which resulted in fatality. While burns did develop, the patient was released from the intensive care service after 2 days and, after skin grafting, had a good outcome at 90-day follow-up. Even after a long delay, decontamination with Hexafluorine® appeared to be beneficial in this case.

The effects of various surface treatments on the shear bond strengths of stainless steel brackets to artificially-aged composite restorations

Abstract Objective: To compare the shear bond strengths (SBS) of stainless steel brackets bonded to artificially-aged composite restorations after different surface treatments. Methods: Forty-five premolar teeth were restored with a nano-hybrid composite (Tetric EvoCeram), stored in deionised water for one week and randomly divided into three equal groups: Group I, the restorations were exposed to 5 per cent hydrofluoric acid for 60 seconds; Group II, the restorations were abraded with a micro-etcher (50 μm alumina particles); Group III, the restorations were roughened with a coarse diamond bur. Similar premolar brackets were bonded to each restoration using the same resin adhesive and the specimens were then cycled in deionised water between 5 °C and 55 °C (500 cycles). The shear bond strengths were determined with a universal testing machine at a crosshead speed of 1 mm/min. The teeth and brackets were examined under a stereomicroscope and the adhesive remnants on the teeth scored with the adhesive remnant index (ARI). Results: Specimens treated with the diamond bur had a significantly higher SBS (Mean: 18.45 ± 3.82 MPa) than the group treated with hydrofluoric acid (Mean: 12.85 ± 5.20 MPa). The mean SBS difference between the air-abrasion (Mean: 15.36 ± 4.92 MPa) and hydrofluoric acid groups was not significant. High ARI scores occurred following abrasion with a diamond bur (100 per cent) and micro-etcher (80 per cent). In approximately two thirds of the teeth no adhesive was left on the restoration after surface treatment with hydofluoric acid. Conclusion: Surface treatment with a diamond bur resulted in a high bond strength between stainless steel brackets and artificially-aged composite restorations and was considered to be a safe and effective method of surface treatment. Most of the adhesive remained on the tooth following surface treatment with either the micro-etcher or the diamond bur.

A comparative study of shear bond strength between metal and ceramic brackets and artificially aged composite restorations using different surface treatments

This in vitro study evaluated the shear bond strength (SBS) between ceramic brackets (CBs) and resin composite restorations (RCRs) prepared using different surface treatments. The findings were also compared with a similar study that used stainless steel brackets (SSBs). Forty-five premolars were restored with a nano-hybrid composite resin (Tetric EvoCeram) and randomly assigned to three surface treatment groups: group 1, 5 per cent hydrofluoric acid (HF); group 2, air abrasion (50 μm alumina particles); and group 3, diamond bur. Specimens were bonded with CBs (Fascination) and exposed to thermo-cycling (500 cycles). The shear force at a crosshead speed of 1 mm/minute was transmitted to brackets. The adhesive remnant index (ARIs) scores were recorded after bracket failure. The analysis of SBS variance (P < 0.01) and chi-square test of ARIs scores (P < 0.01) revealed significant differences among three groups tested. The SBS in group 3 (mean: 26.34 ± 4.76 MPa) and group 2 (mean: 26.68 ± 5.93 MPa) was significantly higher than group 1 (mean: 16.25 ± 5.42 MPa). The SBS was significantly higher in CBs (mean: 23.09 ± 7.19 MPa) compared to SSBs (mean: 15.56 ± 5.13 MPa). High ARIs (100 per cent) occurred in SSBs treated with a diamond bur, whereas CBs primarily failed at the resin-adhesive interface (P < 0.01). In two-thirds of the specimens (SSBs or CBs), no adhesive was left on the restoration after HF conditioning. The ARIs profile of CBs and SSBs that received surface treatments with air abrasion were similar (P > 0.05) and bond failure occurred mainly in adhesive-bracket base and resin-adhesive interfaces. The diamond bur surface treatment is recommended as a safe and cost-effective method of bonding CBs to RCRs.

In vitro orthodontic bracket bonding to porcelain

This in vitro study investigated the influence of using different combinations of bracket, adhesive, and light-curing source on the tensile bond strength to porcelain and on failure patterns at debonding. Tensile tests were performed using: one ceramic bracket versus one metal bracket, two orthodontic composites; type bisphenol A-glycidyldimethacrylate and urethane dimethacrylate (UDMA), and four light-curing units with the same range of emission spectrum but various light intensities: three light-emitting diode (LED) units and one halogen-based unit. One hundred and sixty porcelain samples were randomly divided into 16 equal groups. The porcelain surface was conditioned with 9 per cent hydrofluoric acid before silane application. The composite was photo-polymerized for 40 seconds. After storage in water at 37°C for 24 hours, the samples were subjected to tensile force until bond failure. Bond strength and bond failure mode were recorded; results were analysed (α = 0.05) using R language; linear model with constant variance for the bond strength and multinomial distribution for the failure mode. The bond strength in all groups was sufficient to withstand orthodontic treatment (>6 MPa). There was no statistical difference between the adhesives, but comparing bracket × light interaction, it was significantly higher with the ceramic bracket. No significant differences were seen between the metal bracket groups, but for the ceramic bracket, the results were significantly higher with the LED light. No fracture was observed in porcelain with the metal bracket but it occurred in 35 per cent of the ceramic bracket samples and the risk was higher when using UDMA composite and lower with LED high intensity light.

Shear bond strength of orthodontic brackets to aged resin composite surfaces: effect of surface conditioning

The aim of this study was to investigate the effects of surface conditioning protocols on the shear bond strength (SBS) of metal brackets to aged composite resin surfaces in vitro. Ninety composite resin discs, 6 mm in diameter and 2 mm in height, were prepared and treated with an ageing procedure. After ageing, the specimens were randomly assigned to one of the following groups: (1) control with no surface treatment, (2) 38 per cent phosphoric acid gel, (3) 9.6 per cent hydrofluoric acid gel, (4) airborne aluminium trioxide particle abrasion, (5) sodium bicarbonate particle abrasion, and (6) diamond bur. The metal brackets were bonded to composite surfaces by means of an orthodontic adhesive (Transbond XT). All specimens were stored in water for 1 week at 37°C and then thermocycled (1000 cycles, 5-55°C) prior to SBS testing. SBS values and residual adhesive on the composite surface were evaluated. Analysis of variance showed a significant difference (P = 0.000) between the groups. Group 6 had the highest mean SBS (10.61 MPa), followed by group 4 (10.29 MPa). The results of this study suggest that a clinically acceptable bond strength can be achieved by surface conditioning of aged resin composite via the application of hydrofluoric acid, aluminium trioxide particle abrasion, sodium bicarbonate particle abrasion, or a diamond bur.

Effects of different silanes and acid concentrations on bond strength of brackets to porcelain surfaces

The aim of this study was to determine the optimum silane-coupling agent and the optimum concentration of acid agent when bonding to porcelain surfaces. Eighty deglazed feldspathic porcelain discs with a diameter of 10 mm and a thickness of 2 mm mounted in acrylic resin blocks were randomly divided into four groups. In groups 1 and 2, the porcelain surfaces were etched with 9.6 per cent hydrofluoric (HF) acid and in groups 3 and 4 with 5 per cent HF acid. In groups 1 and 3, the Dynalock maxillary central incisor brackets were bonded with Pulpdent silane and Unite bonding adhesive and in groups 2 and 4 with Reliance silane and Unite. Shear forces were applied to the samples using an Instron universal test machine. The non-parametric Kruskal-Wallis test was used to determine significant differences in bond strengths between the four groups and Dunn's multiple comparison test to compare subgroups. The mean bond strengths and standard deviations of groups 1 to 4 were 5.51 +/- 1.19, 6.54 +/- 0.002, 4.55 +/- 1.93, and 6.39 +/- 0.45 MPa, respectively. Specimens bonded with Reliance showed a statistically significantly higher in vitro bond strength than those bonded with Pulpdent. The concentration of etching gels did not result in any statistically significant difference on the in vitro bond strength when evaluated separately.

The effect of a light-emitting diode on shear bond strength of ceramic brackets bonded to feldspathic porcelain with different curing times

The aim of this study was to evaluate different curing times of a light-emitting diode (LED) unit on shear bond strength (SBS) of ceramic brackets bonded to feldspathic porcelain. Ceramic brackets were bonded with a light-cured adhesive to 96 feldspathic porcelain facets. Air-borne particle abrasion was performed using 25 mum aluminium trioxide (Al(2)O(3)) with an air abrasion device from a distance of approximately 10 mm at a pressure of 2.5 bars for 4 seconds, then the porcelain surfaces were etched with 9.6 per cent hydrofluoric acid for 2 minutes. After surface preparation of the porcelain specimens, silane was applied. In groups 1 and 2, the adhesive was cured with a quartz-tungsten-halogen (QTH) unit for 10 and 20 seconds, respectively. The LED was used in the standard mode for 3, 5, and 10 seconds for groups 3, 4, and 5, respectively. For the other three groups, the LED was used in the fast mode for 3, 5, and 10 seconds, respectively. The SBS of the brackets was measured on a universal testing machine. The adhesive remnant index (ARI) scores, damage to the porcelain, and fracture of the ceramic bracket bases were determined. No significant differences were observed for SBS between the eight groups (P=0.087). There was no significant difference between the groups' ARI scores, porcelain damage, and bracket base fracture (P=0.340, P=0.985, and P=0.340, respectively). There was a greater frequency of ARI scores of 0 for all groups. Fifty per cent of the porcelain facets displayed damage. Nineteen ceramic bracket base fractures were observed. No significant difference was found for the SBS of the groups with QTH and LED units and curing times. It is reliable to use LED with a 3-second curing time since it provided adequate bond strength for ceramic brackets bonded to porcelain surfaces.

Porcelain surface-conditioning techniques and the shear bond strength of ceramic brackets

The aim of this study was to compare the effects of various porcelain surface-conditioning techniques, used either alone or in combination, on the shear bond strength (SBS) of ceramic brackets cured with a light emitting diode (LED). Thirty glazed porcelain facets were randomly divided into three groups of 10. In group I, the porcelain surfaces were etched with 9.6 per cent hydrofluoric acid (HFA) for 2 minutes before silane application, in group II, the porcelain surfaces were sandblasted with aluminium oxide particles, etched with 9.6 per cent HFA for 2 minutes, and silane applied, and in group III, the porcelain surfaces were sandblasted with aluminium oxide particles before silane application. Spirit ceramic brackets were bonded with a light-cured composite resin (Light Bond) and a LED. All specimens were stored in distilled water at 37 degrees C for 24 hours and thermocycled. Bond strength was determined in shear mode at a crosshead speed of 0.5 mm/minute until fracture occurred. Analysis of variance indicated a significant difference between groups (P < 0.001). The lowest SBS was found in group III (5.46 +/- 1.34, P < 0.001). No significant difference was found between group I (11.38 +/- 1.65) and group II (10.45 +/- 1.15; P > 0.05). Surface treatment with HFA and a silane coupling agent produced the highest bond strength. Sandblasting before HFA and silane application did not significantly increase bond strength. Silane application to sandblasted porcelain provided poor results in vitro and clinical trials are needed to determine its reliability for bonding ceramic brackets to ceramic crowns.

Effects of surface conditioning on bond strength of metal brackets to all-ceramic surfaces

The aim of this study was to determine the effectiveness of bonding brackets to ceramic restorations. Sixty feldspathic and 60 lithium disilicate ceramic specimens were randomly divided into six groups. Shear bond strength (SBS) and bond failure types were examined with six surface-conditioning methods: silane application to glazed surface, air particle abrasion (APA) with 25- and 50-microm aluminium trioxide (Al(2)O(3)), etching with 9.6 per cent hydrofluoric acid (HFA), and roughening with 40- and 63-microm diamond burs. Silane was applied to all roughened surfaces. Metal brackets were bonded with light cure composite, then stored in distilled water for 1 week and thermocycled (x500 at 5-55 degrees C for 30 seconds). The ceramic surfaces were examined with a stereomicroscope at a magnification of x10 to determine the amount of composite resin remaining using the adhesive remnant index. The lowest SBS values were obtained with HFA for feldspathic (5.39 MPa) and lithium disilicate (11.11 MPa) ceramics; these values were significantly different from those of the other groups. The highest SBS values were found with 63-microm diamond burs for feldspathic (26.38 MPa) and lithium disilicate (28.20 MPa) ceramics, and were not significantly different from 40-microm diamond burs for feldspathic and lithium disilicate ceramics (26.04 and 24.26 MPa, respectively). Roughening with 25- and 50-microm Al(2)O(3) particles showed modest SBS for lithium disilicate (22.60 and 26.15 MPa, respectively) and for feldspathic ceramics (17.90 and 14.66 MPa, respectively). Adhesive failures between the ceramic and composite resin were noted in all groups. Damage to the porcelain surfaces was not observed. The SBS values were above the optimal range, except for feldspathic ceramic treated with HFA and silane. With all surface-conditioning methods, lithium disilicate ceramic displayed higher SBS than feldspathic ceramic.

Thermodynamic properties of silicalite SiO 2

Silicalite, a polymorph of SiO 2, is a new and interesting molecular-sieve material. Low-temperature (5 to 350 K) heat-capacity, flourine-combustion, high-temperature (350 to 1500 K) drop-calorimetric, and reaction-calorimetric with HF(aq) measurements have been performed on this material. At T′ = 298.15 K, Δ f H m o( T′) = −(905.20±0.84) kJ·mol −1; C p, m o( T′) = (46.34±0.23) J·K −1·mol −1; { Δ 0 T′ S m o( T′)} = (46.29±0.23) J·K −1·mol −1; and Δ f G m o( T′) = −(852.23±0.84) kJ·mol −1. The enthalpies of reaction with 24.4 mass per cent hydrofluoric acid of silicalite at mass concentrations of 0.5, 1, 2, and 4 g·dm −3 were determined to be −(144.91±0.23), −(144.80±0.10), −(145.07±0.12), and −(145.06±0.14) kJ·mol −1, respectively. The enthalpies of reaction of silicalite with 20.1 and 15.0 mass per cent hydrofluoric acid at a silicalite mass concentration of 1 g·dm −3 were determined to be −(143.85±0.19) and −(142.68±0.08) kJ·mol −1, respectively. Because silicalite reacts rapidly with HF(aq) at 298.15 K, it has potential as a reference material for thermochemical measurements on inorganic silicates and silicate minerals. Silicalite is less stable than quartz, cristobalite, or tridymite, but more stable than SiO 2(glass) or the high-pressure forms coesite or stishovite.

A precision enthalpy of solution calorimeter for slow rates of solution. The enthalpy of solution of vitreous silica in hydrofluoric acid

A solution calorimeter capable of measuring the enthalpy of solution in hydrofluoric acid of slowly dissolving silicates is described. A temperature-correction procedure for use with a quartz thermometer is presented. Its validity is demonstrated with measurements of the enthalpy of solution of vitreous silica in 40.2 per cent hydrofluoric acid at 30 °C, by use of the calorimeter both with a constant-temperature jacket and adiabatically.

Extraction of some heavier lanthanides in acidic chloride solutions by di(2-ethylhexyl) phosphoric acid

Equilibrium data have been obtained for the systems MCl 3HClH 2O-1 M D2EHPA (in Amsco Odorless Mineral Spirits), where M is used to designate the trivalent lanthanides Gd, Dy, Er, and Yb, over a wide concentration range of the lanthanide chloride in aqueous solution. For a particular acidity and a given lanthanide concentration in the aqueous phase, the extractability increased as the atomic number of the lanthanide increased. Equilibrium acid concentration was used as a parameter for the equilibrium curves. The general shape of these curves changed as the aqueous acid concentration increased from 1·4 M HCl to 5·0 M HCl. The separation factor of Dy with respect to Gd, β Dy,Gd, was also obtained in acidic chloride solutions. The total lanthanide chloride concentration, the total acidity, and the molar ratio of GdCl 3 to DyCl 3 in the equilibrium aqueous phase had only slight effect on the separation factor. The separation factor was in the range of 9–13 for the conditions studied. It was found that Yb and Lu were not removed from the organic phase by stripping four times with double volumes of 6 M HCl and other methods of back-extracting which have been previously used. A 20 per cent hydrofluoric acid solution, however, completely removed the solute from the organic phase as the insoluble fluoride.

THE CYTOPLASMIC FINE STRUCTURE OF THE DIATOM, NITZSCHIA PALEA.

The cytoplasmic fine structure of the motile, pennate diatom, Nitzschia palea was studied in thin sections viewed in the electron microscope. The cells were fixed in OsO(4), embedded in methacrylate, and immersed in 10 per cent hydrofluoric acid (HF) for 36 to 40 hours to remove the siliceous cell wall prior to sectioning. The HF treatment did not cause any obvious cytoplasmic damage. The dictyosome complex is perinuclear, and located only in the central cytoplasm. Mitochondria are sparse in the central cytoplasm, but abundant in the peripheral cytoplasm, and fill many of the transvacuolar cytoplasmic strands. Characteristic, amorphous oil bodies fill certain cytoplasmic strands and probably are not leucosin. The pyrenoid appears to be membrane limited, and oil droplets are found adjacent to the pyrenoid. The pyrenoid of another diatom, Cymbella affinis, is also membrane-limited. The membrane limiting the pyrenoid may be a composite of the terminal portions of chloroplast discs, facilitating rapid movement of photosynthate into the pyrenoid matrix, where the characteristic oil droplets may be formed. Carinal fibrils are found singly in each carinal pore, and may be involved in the locomotion of Nitzschia palea.

A STAINING METHOD FOR THE QUANTITATIVE DETERMINATION OF FELDSPARS IN ROCKS AND SANDS FROM SOILS

A speedy and accurate staining procedure for the quantitative determination of the feldspars in rocks and sands of soils is proposed. The minerals are treated, by direct contact, with 48 per cent hydrofluoric acid, and then immersed in a concentrated sodium cobaltinitrite solution which stains the potash feldspars yellow. This treatment is followed by immersion in a buffered hematein solution which stains the plagioclase feldspars purple. The depth of colour on the plagioclase depends upon the position in the isomorphous series. Quartz, gypsum and calcite are not affected by the treatment.The quantity of the potash and plagioclase feldspar present is then easily determined by grain counts under the petrographic microscope.

Heats of Formation of Metamorphic Minerals in the System $$Cao-Mgo-Sio_{2}-H_{2}O$$ and Their Petrological Significance

The heats of formation from the oxides for tremolite , anthophyllite , and rankinite and a heat-of-solution value for actinolite have been determined by solution calorimetry. A mixture of 20 per cent hydrochloric and 5 per cent hydrofluoric acid at 81°C. was used as the solvent. The results, corrected for the thermal effects of impurities, are tremolite, cal/mole; anthophyllite, cal/mole; and rankinite, cal/mole. These values combined with other previously determined heats of formation are used to discuss the relative dissociation temperatures of brucite, anthophyllite, and. tremolite: a) Brucite → periclase + , b) Anthophyllite → 7 enstatite + quartz + , c) Tremolite → 2 diopside + 3 enstatite + quartz + . The dissociation temperatures of the minerals at 1 atmosphere vapor pressure are calculated to be brucite, 290° C; anthophyllite, 300° C; and tremolite, 590° C. The dissociation of tremolite to diopside + anthophyllite + quartz + water is shown to be improbable because (1) it would take place at a higher temperature than reaction c and (2) it produces anthophyllite outside its stability field. The equilibrium distribution of calcium and magnesium between the various silicate structures is discussed by the use of thermochemical data and is found to be in excellent agreement with the theoretical predictions of Ramberg. The probability of the stable existence in nature of the mineral assemblage diopside + anthophyllite and the relative equilibrium temperatures of the reactions producing diopside and forsterite during meta-morphism of siliceous dolomites are also discussed.

Properties of Fuming Nitric Acid Affecting Its Storage and Use as a Rocket Propellant

Some of the general problems of storing fuming nitric acid (the system HNO3-NO2-H2O) in closed metal con­ tainers for periods of the order of months at elevated tem­ peratures around 130 F are discussed. A literature review of some of the properties of importance for satisfactory storage and use as a rocket propellant, as well as a discus­ sion of chemical methods of analysis, is included. Two chemical processes which cause problems in the storage of this widely used oxidant are: (a) the corrosion of metal containers causing change in composition of the acid and its contamination with metallic salts, and (b) the thermal decomposition of acid lean in NO2 and H 20 with accom­ panying high pressures and changes in composition of the oxidant. Liquid and gas phase corrosion of aluminum al­ loys and of stainless steel alloys of the 18-8 class are found to be markedly inhibited by the presence of about 0.5 wt per cent hydrofluoric acid in the fuming nitric acid, thus reducing the first problem of storage. The mechanism of passivation appears to be the formation of an impervious coating of insoluble metal fluoride on the surface of the metal. The second problem of thermal decomposition and correspondingly excessive storage pressures is elimi­ nated in acid containing enough NO2 (12 to 16 wt per cent) to obtain the results desired without causing high partial pressure of this species, and enough H 20 (2 to 3V2 wt per cent) to give satisfactory results without unduly diluting the oxidizing power.

LEAF ORGANIZATION OF SOME WOODY DICOTYLEDONS FROM NEW ZEALAND

American Journal of BotanyVolume 41, Issue 3 p. 186-191 Article LEAF ORGANIZATION OF SOME WOODY DICOTYLEDONS FROM NEW ZEALAND Robert B. Wylie, Robert B. Wylie Department of Botany, State University of Iowa, Iowa City, IowaSearch for more papers by this author Robert B. Wylie, Robert B. Wylie Department of Botany, State University of Iowa, Iowa City, IowaSearch for more papers by this author First published: 01 March 1954 https://doi.org/10.1002/j.1537-2197.1954.tb14324.xCitations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume41, Issue3March 1954Pages 186-191 RelatedInformation