An investigation into the mechanisms of adherence between borosilicate glass and steatite ceramic and between borosilicate glass and alumina ceramic

A qualitative evaluation was made of the adherence between borosilicate glass and the ceramics, steatite and alumina. Three basic adherence studies were performed. (1) A comparison between the x-ray diffraction patterns of the ceramic and the fused glass-ceramic powder mixture was made to determine if any new compounds were formed at 1200°C. (2) A metallographic examination of the interfacial region of actual seals made at 800°, 900°, 1000°, 1100°, and 1200°C was made to observe the transition zone and any new phases formed. (3) A hydrostatic rupture test and a metallographic and stereoscopic examination of the resulting fracture surfaces were made in order to get a qualitative evaluation of the adherence developed in seals formed at various temperatures. The results of each investigation indicated that good glass-ceramic adherence was achieved. The x-ray diffraction work suggested that new compounds were formed at both glass-ceramic interfaces. In the alumina system, the resulting diffraction pattern closely resembled both an aluminum borate and an aluminum silicate. In the steatite system, a close match was not made, but the new pattern did resemble magnesium meta silicate. The metallographic work revealed that, in the steatite system, extensive interdiffusion of the glass and ceramic phases occurred. Devitrivication was observed in seals made at 1200° C, and cracks appeared when these seals were cooled. Neither phase in the alumina system was so obviously affected by high temperatures. A few small crystals were found on the ceramic at the interface, and glass filled some of the ceramic voids near the interface, but evidence of extensive diffusion was not observed. The hydrostatic rupture test data showed that the strength of the alumina seals improved with temperature. Similar data were not collected for the steatite seals, for too many samples broke improperly. Examination of the fracture surfaces in both systems indicated that the crack generally propagated through the glass phase. This suggests that the solid-liquid interfacial energy is somewhat smaller than the solid-gas interfacial energy, or the energy of adherence is large

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

A pneumatic vibrotactile stimulation device for fMRI.

Mapping the functional response of the somatosensory cortex is useful both for characterizing normal brain activity and for determining the functional integrity of damaged cortex compromised by stroke or other neurological insults. A variety of stimulators have been used to produce somatosensory cortex activation in functional brain imaging, including brushes and swabs operated manually, pneumatically and mechanically powered mechanical vibrators, air puffs, and vibrating ceramic piezoelectric wafers and benders. A closed-system, pneumatically driven rubber diaphragm is reported that overcomes many of the limitations of existing vibrotactile devices and produces robust sensory cortex activation in an fMRI experiment

Research needs for mining and industrial solid waste disposal

Report of a workshop held at Colorado State University, Fort Collins, Colorado, July 22 and 23, 1976.CER76-77JN13.Under the sponsorship of the National Science Foundation, through the initiative of the Embankment Dams and Slopes Committee of ASCE; NSF Grant No. ENG 76-09380

What Should the Ideal HIV Self-Test Look Like? A Usability Study of Test Prototypes in Unsupervised HIV Self-Testing in Kenya, Malawi, and South Africa

HIV self-testing (HIVST) is increasingly being sought and offered globally, yet there is limited information about the test features that will be required for an HIV self-test to be easy to use, acceptable to users, and feasible for manufacturers to produce. We conducted formative usability research with participants who were naïve to HIVST using five prototypes in Kenya, Malawi, and South Africa. The tests selected ranged from early-stage prototypes to commercially ready products and had a diverse set of features. A total of 150 lay users were video-recorded conducting unsupervised self-testing and interviewed to understand their opinions of the test. Participants did not receive a test result, but interpreted standardized result panels. This study demonstrated that users will refer to the instructions included with the test, but these can be confusing or difficult to follow. Errors were common, with less than 25 % of participants conducting all steps correctly and 47.3 % of participants performing multiple errors, particularly in sample collection and transfer. Participants also had difficulty interpreting results. To overcome these issues, the ideal HIV self-test requires pictorial instructions that are easy to understand, simple sample collection with integrated test components, fewer steps, and results that are easy to interpret