Constitution and Specific Gravity of the Ternary Mattes Cu\u3csub\u3e2\u3c/sub\u3eS-FeS-PbS.

The constitution of the ternary mattes CU2S-FeS-PbS has never been completely investigated. Fulton and Goodner 1) have investigated the binary mattes CU2S-FeS, CU2S-PbS, PbSFeS and have shown that the three binaries show eutectics. There has been no attempt however to draw the complete ternary diagram. The following work is intended to be a contribution toward the completion of this diagram by first of all pointing out those mattes which separate on melting into two layers, and second by determining the specific gravities of mattes of different compositions

Comparison of AMZIRC and GRCop-84

The mechanical properties of two copper alloys with high thermal conductivity, GRCop-84 and AMZIRC, were compared. These are competing alloys in high temperature, high heat flux applications such as rocket nozzles. The GRCop-84 data presented was taken from previous work. The results of new tensile, creep, and compression tests on AMZIRC are presented. Tests were done on as-received hard drawn material, and on material that had been subjected to a heat treatment designed to simulate a brazing operation at 935 C. As-received AMZIRC was found to have excellent properties at temperatures below 550 C, with room temperature yield and ultimate tensile strengths of about 500 MPa, and ductile failures. By comparison, GRCop-84 s room temperature tensile yield and ultimate strengths are about 200 and 380 MPa respectively. However, the simulated brazing heat treatment substantially decreased the mechanical properties of AMZIRC; and the strength of as-received AMZIRC dropped precipitously as test temperatures exceeded 500 C. The properties of GRCop-84 were not significantly affected by the 935 C heat treatment. As a result, there appear to be advantages to GRCop- 84 over AMZIRC if use or processing temperatures of greater than 500 C are expected. Tensile creep tests were done at 500 and 650 C. At these temperatures, the creep properties of GRCop-84 were superior to AMZIRC s. At equivalent rupture life and stress, GRCop-84 was found to have a 150 C temperature advantage over AMZIRC; for equivalent rupture life and temperature GRCop-84 was two times stronger

A one-dimensional color order system for dental shade guides

The purpose of this study was to re-arrange the master Bioform shade guide into a long-range one-dimensional color system based upon color difference. Although most shade guides may show local order when arranged according to hue, long-range order has not been established. However, shade guide arrangement according to a logical color order would be an advantage to the user. The first step in determining the color order was to measure the color of the shade guide teeth. A methodology was developed for measuring the color by use of a reflectance spectrophotometer. The precision of measurement was determined to be equal to CIE L*a*b* [Delta]E of 0.5. Spectra were obtained and converted into CIE L*a*b* and Munsell notation. The measured colors of the Bioform shades ranged from a Munsell hue of 0.9 Y to 3.5 Y; a value of 6.6 to 7.8; and a chroma of 1.9 to 4.1. The teeth were then arranged visually from light to dark. The correlation coefficient between the visual ranking and color difference was 0.95. There was an inverse correlation between visual ranking and Munsell value, with a correlation coefficient of 0.90. Therefore, the sequence according to color difference provided the better agreement with visual perception.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27704/1/0000090.pd

Evaluation of some properties of an opaque porcelain fired simultaneously with the body porcelain,

Recently, a porcelain-fused-to-metal opaque porcelain was introduced that does not require a separate firing before application of the body porcelain. The objective of this study was to determine the properties of this new opaque porcelain and its ability to bond to metal. The properties studied included flexural strength, linear firing shrinkage, coefficient of thermal expansion, powder particle size, and ability to bond to body porcelain and dental alloys. Sintering of this opaque porcelain was complete when fired at 1760 [deg] F (960 [deg] C) with a linear firing shrinkage of 13.1% +/- 0.2%. No boundary between the opaque and body porcelains could be found with a scanning electron microscope after firing at 1760 [deg] F (960 [deg] C). The mean flexural strengths were 99 +/- 7 and 101 +/- 8 MPa respectively, for this opaque porcelain and a conventional opaque porcelain, and were not significantly different as assessed with Student's t-test (p = 0.548). The coefficient of thermal expansion for this opaque porcelain was 13.3 +/- 0.2 x 10-6/ [deg] C. Particle size analysis showed a 63% increase in the particles below 5 [mu]m for this opaque porcelain and bonding to two alloys was adequate as indicated by its cohesive failure. Simultaneous firing of this special opaque porcelain and body porcelain produced satisfactory sintering, strength, and bonding to metal.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31266/1/0000172.pd

Utilization Rates of Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death: A 2012 Calculation for a Midwestern Health Referral Region

Background Utilization rates (URs) for implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death (PPSCD) are lacking in the community. Objective To establish the ICD UR in central Indiana. Methods A query run on two hospitals in a health information exchange database in Indianapolis identified patients between 2011 and 2012 with left ventricular ejection fraction (EF) ≤0.35. ICD-eligibility and utilization were determined from chart review. Results We identified 1,863 patients with at least one low-EF study. Two cohorts were analyzed: 1,672 patients without, and 191 patients with, ICD-9-CM procedure code 37.94 for ICD placement. We manually reviewed a stratified (by hospital) random sample of 300 patients from the no-ICD procedure code cohort and found that 48 (16%) had no ICD but had class I indications for ICD. Eight of 300 (2.7%) actually had ICD implantation for PPSCD. Review of all 191 patients in the ICD procedure code cohort identified 70 with ICD implantation for PPSCD. The ICD UR (ratio between patients with ICD for PPSCD and all with indication) was 38% overall (95% CI 28–49%). URs were 48% for males (95% CI 34–61%), 21% for females (95% CI 16–26%, p=0.0002 vs males), 40% for whites (95% CI 27–53%), and 37% for blacks (95% CI 28–46%, p=0.66 vs whites). Conclusions The ICD UR is 38% among patients meeting Class I indications, suggesting further opportunities to improve guideline compliance. Furthermore, this study illustrates limitations in calculating ICD UR using large electronic repositories without hands-on chart review

Effect of parallel surface cuts on bonding to dentine

The strength of adhesive joints has been found to result from combinations of micromechanical, chemical and diffusion components depending on the system1. The development of adhesives that bond dental restorative materials to human dentine has been a major advance in the science of dental materials. The purpose of this investigation was to study the contribution of parallel surface cuts on the joint strength of dentine adhesives. Half of the specimens were finished with 60 grit SiC paper as a control. The other half were polished with 600 grit SiC paper and then finished with an instrument that produced a series of parallel surface cuts. A two-way analysis of variance showed that both the surface preparation and the adhesive system had a significant effect on shear bond strength (p < 0.0001). In general, the samples finished with parallel surface cuts gave shear bond strength values about double those finished with silicon carbide alone. For those control samples prepared with a 60 grit surface, the predominant type of failure was at the tooth/adhesive interface. The majority of samples with parallel surface cuts failed cohesively within the adhesive system. The experimental instrument is designed to produce retentive grooves or undercuts in the dentine surface which enhance micromechanical adhesion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31465/1/0000387.pd

Heart Rate Variability Declines with Increasing Age and CTG Repeat Length in Patients with Myotonic Dystrophy Type 1

Background: Cardiac myopathy manifesting as arrhythmias is common in the neurological disease, myotonic dystrophy type 1 (DM1). The purpose of the present study was to evaluate heart rate variability (HRV) in patients with DM1. Methods: In a multicenter study, history, ECG, and genetic testing were performed in DM1 patients. Results: In 289 patients in whom the diagnosis of DM1 was confirmed by a prolonged cytosine-thymine-guanine (CTG) repeat length the most common ambulatory ECG abnormality was frequent ventricular ectopy (16.3%). The 24-hour time domain parameters of SDNN (SD of the NN interval) and SDANN (SD of the mean NN, 5-minute interval) declined as age and CTG repeat length increased (SDNN: −8.5 ms per decade, 95% confidence intervals [CI]−12.9, −4.2, −8.7 ms per 500 CTG repeats, CI −15.7, −1.8, r = 0.24, P < 0.001; SDANN: −8.1 ms per decade, CI −12.4, −3.8, −8.8 ms per 500 CTG repeats, CI −15.7, −1.9, r = 0.23, P < 0.001). Short-term frequency domain parameters declined with age only (total power: −658 ms2 per decade, CI: −984, −331, r = 0.23, P < 0.001; low frequency (LF) power −287 ms2 per decade, CI: −397, −178, r = 0.30, P < 0.001; high frequency (HF) power: −267 ms2 per decade, CI: −386, −144, r = 0.25, P < 0.001). The LF/HF ratio increased as the patient aged (0.5 per decade, CI: 0.1, 0.9, r = 0.13, P = 0.03). Conclusions: In DM1 patients a decline in HRV is observed as the patient ages and CTG repeat length increases.    

Sources of color variation on firing porcelain

The final color matching of porcelain crowns depends upon the accuracy of the original shade matching by the dentist and variables introduced during processing. Possible sources of processing variables include thickness and color of the opaque, thickness, color, and translucency of the body and enamel layers, firing temperature, and number of firings (Miller, 1987). These processing variables can lead to an error in shade match. The purpose of this study was to quantify, in CIE [Delta]E units: (1) the shade variations when the same batches are fired, (2) the shade variations between different batches, and (3) the differences in color produced by the multiple firing. Three lots of six shades of four commercial brands were included in this study. The color variation of the opaque samples (mean [Delta]E was 0.46) was generally lower than that of the body/opaque samples (mean [Delta]E was 0.86). The average color variation for three different batches of the body/opaque samples was 1.44. The average color difference produced as a result of multiple firings was 1.00 after six firings, compared with the color after three firings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29247/1/0000304.pd

Clinical care recommendations for cardiologists treating adults with myotonic dystrophy

Myotonic dystrophy is an inherited systemic disorder affecting skeletal muscle and the heart. Genetic testing for myotonic dystrophy is diagnostic and identifies those at risk for cardiac complications. The 2 major genetic forms of myotonic dystrophy, type 1 and type 2, differ in genetic etiology yet share clinical features. The cardiac management of myotonic dystrophy should include surveillance for arrhythmias and left ventricular dysfunction, both of which occur in progressive manner and contribute to morbidity and mortality. To promote the development of care guidelines for myotonic dystrophy, the Myotonic Foundation solicited the input of care experts and organized the drafting of these recommendations. As a rare disorder, large scale clinical trial data to guide the management of myotonic dystrophy are largely lacking. The following recommendations represent expert consensus opinion from those with experience in the management of myotonic dystrophy, in part supported by literature-based evidence where available