Effects of Solvents in the Polyethylene Glycol Series on the Bonding of Copper Joints Using Ag2O Paste

The effects of reducing solvents on the bonding process using silver oxide paste in a copper joint were investigated. Three solvent types were tested: diethylene glycol (DEG), triethylene glycol (TEG), and polyethylene glycol (PEG). The strength of the joints was assessed by fracturing, which occurred at the interface of the copper oxide layer and the copper substrate in DEG and TEG samples and at the bonded interface in the PEG sample. Analysis of the samples revealed that, in the DEG and TEG samples, the copper substrate was oxidized during the bonding process, which compromised the shear strength of the joints. In contrast, the PEG sample exhibited nonuniform sintering of the silver layer while retaining good shear strength. It was found that the combination of DEG and PEG produced optimum shear strength in the copper joint, as PEG suppressed the growth of copper oxide and DEG promoted the formation of a dense sintered silver layer. The bonding strength achieved was higher than that of the gold-to-gold joint made using standard Pb-5Sn solder.     

Distribution of double bonds in thermally degraded polyisobutylene

The distribution of double bonds in thermally degraded polyisobutylene was determined quantitatively by using pulsed Fourier transform ¹H n.m.r. spectroscopic analysis. The double bonds in the degraded polymer did not exist in the interior but at the terminal positions of the polymer chain. These olefins were of the terminal trisubstituted and terminal vinylidene types. The content of the former was much greater than that of the latter. This shows that radical chain transfer predominantly occurs at the methylene hydrogen rather than at the methyl groups of the polymer chain. The average number of double bonds per molecule, f, was greater than 1 and tended to be near 2. Thereby most of the degraded polyisobutylene was shown to have two terminal unsaturations per molecule.     

Group behavior of agents with an emotional model

Recently, there has been much interest in the study of the formation of groups of agents that cause interactions between agents and invent new functions. We gave some agents an action rule based on the interactions of human feelings by using a circumplex model. It had been decided that the parameters of feelings in this model should have only two axes. In this report, eight basic action dimensions and pure feelings on four corresponding axes were given to agents as a model of feelings and actions based on the multiple factor analysis theory of R. Plutchik, and the behavioral characteristics of the group of agents were examined.     

Micro‐ and nanoscale structures of mesiodens dentin: Combined study of FTIR and SAXS/WAXS techniques

A mesiodens is the most common type of supernumerary tooth present in conjunction to normal dentition. A mesiodens may commonly occur in the central region of the upper or lower jaw. A mesiodens is different from normal teeth in terms of structure and shape. The aim of this study is to evaluate the micro‐ and nanoscale structural properties of mesiodens dentin by combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and Fourier transform infrared (FTIR) spectroscopy. Five freshly extracted, noncarious mesiodens and five normal dentin disks prepared from human incisor teeth were compared. Using FTIR, the phosphate‐to‐amide I, carbonate‐to‐phosphate, and carbonate‐to‐amide I band area ratios and the crystallinity index were quantified. SAXS/WAXS were used to study the nanostructure of mesiodens. An increase in the mineral content in the mesiodens dentin with respect to the normal group was found. Crystallinity was also significantly increased and the protein content decreased in the mesiodens dentin compared with that of normal dentin. SAXS/WAXS results revealed that mesiodens dentin has a more calcified tissue. Further, SAXS analysis revealed a nonuniform distribution of dentin fibrils in mesiodens. Microsc. Res. Tech., 78:52–58, 2015. © 2014 Wiley Periodicals, Inc.     

Fissure formation and subsurface subsidence in a coalbed fire

Coalbed fires are uncontrolled subsurface fires that occur around the world. These fires are believed to be significant contributors to annual CO₂ emissions. Although many of these fires have been burning for decades, researchers have only recently begun to investigate physical mechanisms that control fire behavior. One aspect of fire behavior that is poorly characterized is the relationship between subsurface combustion and surface fissures. At the surface above many fires, long, wide fissures are observed. At a coalbed fire near Durango, Colorado, these fissures form systematic orthogonal patterns that align with regional joints in the Upper Cretaceous Fruitland Formation. Understanding the mechanisms that form these fissures is important, as the fissures are believed to play vital roles in sustaining the combustion in the subsurface. In some of the coalbed fire simulation models available today, these fissures are treated as fixed boundary conditions. We argue, using data collected, field observations and simulation result, that there exists a relationship between the location and magnitude of subsidence caused by the fire and the opening of fissures. The results presented suggest that fissures are believed to open when subsurface subsidence gives rise to tensile stresses around pre-existing joints.     

STEAM DRYING OF SINTERED SPHERES OF GLASS BEADS

ABSTRACT

Superheated steam drying of sintered spheres of glass beads with different diameters is investigated to reveal the effects of the gravitational force on drying rates. In a previous study, the drying rate curves of small samples with coarse glass beads in which the frictional resistance to flow of water and the effect of the gravitational force are negligible, were predicted by an evaporation zone model.In the present investigation, the drying rate curves of sintered spheres of glass beads with diameters ranging from 1.53×10^-2m to 4.99×lO^-2m are experimentally and theoretically obtained, and also the capillary pressure curves are measured by use of Haines' apparatus. The drying rate curves of large samples in which the effect of the gravitational force can not be negligible, are compared with those for small samples and the difference among these curves is discussed in terms of the moisture distributions which are estimated from the evaporation zone model with the observed capillary pressure curves.     

Synthesis of an AlN Polycrystalline Bulk Layer and Nanotubes by Using NH3 and Bi

A bulk layer of aluminum nitride (AlN) polycrystals was synthesized on a boron nitride crucible surface by heating Al chunks with 5 mol% of bismuth at 1273 K for 3 h under NH₃ gas flow. The fragments of the layer were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The platelet grains of AlN with a size of 0.1–1.0 μm and having preferred orientation of the c -axis perpendicular to the layer were formed at the crucible side. Nanotubes 6–15 μm long and about 20–100 nm thick grew on the gas phase side of the layer.     

Perspectives on the role of the lateral pterygoid muscle and the sphenomandibular ligament in temporomandibular joint function

This is a phase II study to evaluate the efficacy and toxicity of short-course carboplatin in advanced-stage nasopharyngeal carcinoma (NPC). Thirty-three previously untreated stage III-IV NPC patients were studied. Carboplatin was given as a rapid intravenous injection every 3 weeks. The dose of carboplatin was calculated according to the individual patient's creatinine clearance and desired platelet nadir of 75,000/microliter according to the Egorin formula. Response and toxicity were evaluated. Thirty-two patients were evaluated for response. The median age was 54 years, range 30-70 years. Twenty-four patients had local regional disease and 8 patients had metastatic disease. The median dose of carboplatin given was 415 mg/m2 (range 91-791 mg/m2). Fourteen (44%) patients had a partial response with a 95% confidence interval of 26-62%. Fifteen (47%) patients had stable disease and 3 (9%) progressive disease. The overall median survival rate was not reached at 43 months. Overall toxicity was tolerable. Grade III-IV myelosuppression occurred in 4 (12%) patients. There were no other major toxicity- or treatment-related deaths. We conclude that carboplatin has a significant anticancer effect in advanced NPC. Thus carboplatin combination chemotherapy for the treatment of NPC is worthy of future clinical investigations.