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Aim: The aim of the present study was to compare postoperative pain in single visit endodontics using heat-treated nickel - titanium file systems (ProTaper Gold, HyFlex EDM, V Taper 2H). Methods: Sixty patients requiring endodontic treatment in vital permanent lower molars with irreversible pulpitis were included in the study. Patients were divided into three groups each containing 20 patients: Group 1 teeth prepared with ProTaper Gold (Dentsply), Group 2 HyFlex EDM (Coltene), and Group 3-V Taper 2H (SS WHITE). Treatment was performed in a single visit. The severity of the postoperative pain was assessed by the Visual Analog Scale after 2, 4, 8, 12, 24, and 48 h. Data were analyzed using the Kruskal-Wallis tests. Results: There was no significant difference in the incidence of postoperative pain among the three groups. There was significant reduction in pain from preoperative till the end of 2 days, irrespective of the file systems used. When compared between the three groups. There was no significant difference in pain scores at different time intervals. When change in pain from preoperative to different time intervals was compared, there was no significant difference between all three groups. V Taper 2H files showed increased pain scores from 4 to 12 h, however, the pain reduced thereafter till 48 h with no significant statistical difference. Conclusion: Results of this in vivo study showed that there was no significant difference in the incidence of postoperative pain among the three groups. [ABSTRACT FROM AUTHOR]

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Systematic investigations on the fatigue strength of heat treated sintered steels with notched specimens are barely found in the literature, especially at stress ratios other than R = −1. For that reason a larger study was initiated with the aim to provide a base for safe estimates of fatigue strengths also for heat treated components. This work deals with one possibility to design a Haigh diagram for the positive mean stress range beyond R = −1. Starting point is a new approach to determine the mean stress sensitivity M. As all equations derived are based on averages, in extreme cases individual test results can deviate by more than 20% from the calculated value. Regularly, however, deviations around ±10% are observed. [ABSTRACT FROM AUTHOR]

Salmonella enterica subsp. enterica serovar Newport is a bacterial foodborne pathogen isolated from several environmental reservoirs on the Delmarva Peninsula and has been associated with several produce-related outbreaks. However, little is known about specific interactions between Salmonella Newport and soil amendments used as fertilizers. The purpose of this study was to determine Salmonella Newport persistence and resuscitation in raw poultry litter (PLR), a common biological soil amendment, and in soils containing poultry litter–based (heat-treated poultry pellets [HTPP]) or chemical fertilizer (urea [U]) amendments to provide equivalent levels of nitrogen to the soil. Inoculated samples were stored in a growth chamber and irrigated regularly over 4 weeks. Soil samples were collected every week for 4 weeks to determine moisture content and surviving Salmonella Newport populations (log CFU per gram dry weight). Data were analyzed by using a one-way analysis of variance and Student's t test. The PLR supported significantly higher (5.07 log CFU/g dry weight [gdw]) populations of Salmonella Newport than HTPP only (1.70 log CFU/gdw). However, PLR-amended (PRLA) soil (2.5 log CFU/gdw) samples had significantly (P < 0.05) lower Salmonella Newport populations compared with HTPP-amended (4.5 log CFU/gdw) and U-amended (4.0 log CFU/gdw) soil samples. The effect of irrigation on Salmonella Newport population levels in PRLA soils was significant, and in a comparative study, the overall increase in the pathogen levels in U-amended soil (mean = 1.12 log CFU/gdw) was significantly greater than that in PLRA soil (mean = 0.54 log CFU/gdw), whereas that in HTPP-amended soil (0.80 log CFU/gdw) was not significantly different from PLRA soil. Raw poultry litter supported higher Salmonella populations compared with treated. Irrigation significantly increased Salmonella populations in all tested amendments. Pathogen survival in amended soil relies on complex soil and environmental interactions. [ABSTRACT FROM AUTHOR]

Aluminum alloys are heat treated to provide optimal material properties for use in a variety of applications. However, when exposed to abnormally high temperatures, an evaluation must be performed to determine if the aluminum component has been compromised. Nondestructive evaluation of aluminum alloys, by means of electrical conductivity and hardness tests, can assist in determining the condition of the part. These techniques require experience and engineering judgment to properly interpret the data produced in order to determine whether a part needs to be replaced. This article will elaborate on issues with these nondestructive techniques to help diagnose the condition of aluminum alloys exposed to high temperatures. [ABSTRACT FROM AUTHOR]

A manufacturer of hex bars experienced occasional post heat treatment cracking. Metallography, SEM fractography, and microhardness testing demonstrated that quench cracking was the cause of failure. The manufacturer had the heat treatment modified in order to eliminate the cause of failure. [ABSTRACT FROM AUTHOR]

In this paper, the effect of heat treatment and number of passes on microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy samples were investigated. From six samples of as-cast AZ91C magnesium alloy, three plates were pre-heated at temperature of 375°C for 3 hours, and then were treated at temperature of 415°C for 18 hours and finally were cooled down in air. Three plates were relinquished without heat treatment. 8 mm thick as-cast AZ91C magnesium alloy plates were friction stir processed at constant traverse speed of 40 mm/min and tool rotation speed of 1250 rpm. After process, microstructural characterization of samples was analyzed using optical microscopy and tensile and Vickers hardness tests were performed. It was found that heat treated samples had finer grains, higher hardness, improved tensile strength and elongation relative to non-heat treated ones. As the number of passes increased, higher UTS and TE were achieved due to finer grains and more dissolution of β phase (MgAl). The micro-hardness characteristics and tensile improvement of the friction stir processed samples depend significantly on grain size, removal of voids and porosities and dissolution of β phase in the stir zone. [ABSTRACT FROM AUTHOR]

A sample from a large gear was submitted for investigation into the cause of apparent macropitting observed around the pitch line on the loaded face of one of the teeth. A banded (light and dark etching) martensitic structure was observed, which varied significantly in hardness. Cracking was observed to be isolated to the case-hardened surface. The macropitting observed appeared to be consistent with contact fatigue. The nonhomogeneous microstructure observed may have been particularly susceptible to fatigue initiation and propagation. The microstructure observed appeared to be due to a lack of homogenous diffusion of carbon during the austenization of the part from the annealed condition. [ABSTRACT FROM AUTHOR]

Steak knives from three different suppliers were brought to our facility to conduct a comparative analysis of their metallurgical properties. Although they have allegedly been used and cleaned in similar conditions in several restaurants across North America, only knives coming from one supplier showed signs of premature corrosion. Our investigation found that even though they have similar chemical and mechanical properties, and had been submitted to the same heat treatment, major microstructure discrepancies made some of these knives prone to rapid corrosion. As per our examination, the prematurely corroded knives experienced extensive chromium carbides precipitation during heat treatment, which determined a massive chromium depletion of the matrix and lowered their corrosion resistance. On the contrary, the knives that never corroded kept all their chromium content inside the matrix, thus contributing to better corrosion resistance. [ABSTRACT FROM AUTHOR]

Salinicoccus roseus is the most commonly occurring bacterium in salt-cured fish having red discoloration. In the present work, sterile crystalline salt and semiground salt were inoculated with 6 logs level of this bacterium. Half of each of the salt batches was heat-treated at 80°C for 30 mm in order to inactivate the inoculated bacteria, while the remaining halves were used as positive controls. The four salt qualities were used in curing of sciaenids (Johnius dussumieri or Dussumieri's croaker). Red discoloration, bacteriological, physical, and biochemical quality parameters were monitored at quarterly intervals for 1 year. The control sciaenids were discarded at the end of 3 mo due to complete red discoloration. The heat-treated crystalline and semiground salt-cured fish were free from red discoloration for 6 and 9 months of storage, respectively. The quality degradation, measured as increases in total volatile nitrogen (TVN) and peroxide values (PV), was also considerably slower in fish cured with heat- treated salt than in the control. Furthermore, the development of TVN and PV values was significantly slower in fish cured with heat-treated semi- ground salt than in fish cured with heat-treated crude salt. The present study revealed that using heat-treated solar salt to cure fish enhances shelf life 6 to 9 months longer than that of the control. [ABSTRACT FROM AUTHOR]

The effects of heat treatment on stilpnomelane from granite pegmatites at Zółkiewka (Lower Silesia, Poland) were studied using 57Fe Mössbauer spectroscopy. Samples of naturally altered stilpnomelane and chlorite were also studied. The Mössbauer spectrum of an untreated sample was fitted to two Fe2+ doublets and two Fe3+ doublets. The Fe2+ doublets had similar isomer shifts (1.13 and 1.16 mm/s for the octahedral M1 and M2 sites), different quadrupole splitting values (QS = 2.28 and 2.66 mm/s, respectively), and an M1:M2 area ratio of nearly 1:3. For ferric iron, the first doublet was assigned to the combined M1 + M2 + M4 octahedral positions and had IS = 0.41 and QS = 1.18 mm/s. The second doublet was assigned to the M3 site, with parameters IS = 0.36 and QS = 2.07 mm/s. This is characteristic for stilpnomelane. The oxidation of Fe2+ is fast at low temperatures, with a maximum at 360 °C. Near 1050 °C, the stilpnomelane structure broke down completely, and the spectrum consisted of two sextets and two ferric iron doublets. The predominant phase in this new material is hematite, as represented by the two sextets. The abnormally high fractional Fe2+ content in the altered stilpnomelane (0.70) as compared to the untreated sample (0.45) indicates that the sample was subjected to local hydrothermal processes. Nearly identical divalent iron contents and hyperfine parameters for the Fe2+ and Fe3+ doublets (except Fe3+ in M3) in the altered stilpnomelane and associated chlorite strongly suggest that chlorite is transformed into stilpnomelane. [ABSTRACT FROM AUTHOR]

Hot steam corrosion tests were performed on heat-treated Al coated NdFeB magnets. The results suggest that the corrosion process can be divided into different stages. Initially, Nd which diffuses across the Al coating from the Nd-rich grain boundaries of the magnet during annealing, reacts with the moisture forming either Nd oxide or hydroxide at the surface. Upon further corrosion, the brittle Al-Fe-Nd-O-B compounds are formed, and they appear as lumps of oxides or hydroxides of Nd and Fe on the coating layer. And finally, the whole coating is consumed due to corrosion, and the corrosion process proceeds into the magnet material forming mostly Fe oxide or hydroxides. Among various annealed coated magnets, the one which is heat treated at 500/spl deg/C for 10 mins has the highest corrosion resistance against the moist and salty environment. [ABSTRACT FROM PUBLISHER]