Dalton's and Amagat's laws fail in gas mixtures with shock propagation.

A shock propagating through a gas mixture leads to pressure, temperature, and density increases across the shock front. Rankine-Hugoniot relations correlating pre- and post-shock quantities describe a calorically perfect gas but deliver a good approximation for real gases, provided the pre-shock conditions are well characterized with a thermodynamic mixing model. Two classic thermodynamic models of gas mixtures are Dalton's law of partial pressures and Amagat's law of partial volumes. We measure post-shock temperature and pressure in experiments with nonreacting binary mixtures of sulfur hexafluoride and helium (two dramatically disparate gases) and show that neither model can accurately predict the observed values, on time scales much longer than that of the shock front passage, due to the models' implicit assumptions about mixture behavior on the molecular level. However, kinetic molecular theory can help account for the discrepancy. Our results provide starting points for future theoretical work, experiments, and code validation.

A low cost point-of-care viscous sample preparation device for molecular diagnosis in the developing world; an example of microfluidic origami.

The lab-on-a-chip concept has led to several point-of-care (POC) diagnostic microfluidic platforms. However, few of these can process raw samples for molecular diagnosis and fewer yet are suited for use in a resource-limited setting without permanent electrical infrastructure. We present here a very low cost paper microfluidic device for POC extraction of bacterial DNA from raw viscous samples--a challenge for conventional microfluidic platforms. This is an example of "microfluidic origami" in that the system is activated by folding; demonstrated here is room temperature cell lysis and DNA extraction from pig mucin (simulating sputum) spiked with E. coli without the use of external power. The microfluidic origami device features dry reagent storage and rehydration of the lysis buffer. We demonstrate DNA extraction from samples with a bacterial load as low as 33 CFU ml(-1). Extraction times, starting from the raw sample, have been optimized to about 1.5 h without the use of external power, or to within 1 h using an oven or a heater block. The fabrication of this paper microfluidic device can be translated into high volume production in the developing world without the need for a semiconductor clean room or a microfabrication facility. The sample preparation can be performed with the addition of just the sample, water, ethanol and elute buffer to the device, thus reducing chemical hazards during transport and handling.

Native American recruitment into breast cancer screening: the NAWWA project.

BACKGROUND: American Indian women's historically low breast cancer incidence and mortality rates have gradually increased such that in many parts of the United States they equal "U.S. All Races" rates. Thus, American Indian women need screening to maintain their low rates. METHODS: In an outreach program, local American Indian women were trained as lay health advisers, "Native Sisters," to locate and contact American Indian women in the Denver metropolitan area and provide education and encouragement to increase participation in mammography screening. Participation was monitored and interviews collected descriptive information and information about risk factors for breast cancer. An interrupted-time-series design was used to assess changes in mammography participation. RESULTS: The NAWWA program increased recruitment of American Indian women (p < 0.05). Women recruited by the Native Sisters were more likely to be currently on hormone replacement therapy and to be menopausal. CONCLUSIONS: The lay health adviser program was effective in recruiting American Indian women to have screening mammography. Barriers to participation were complex and often involved cultural values and beliefs.

Guidelines for the restoration of Class V lesions.

Approximately 18 percent of all permanent teeth have Class V lesions. In addition, the prolonged retention of teeth in an increasingly older population is expected to increase the prevalence of Class V lesions. Much has been written about the merits of various techniques for restoring such lesions, but little information is available comparing and contrasting all the material and procedural options available to the general dentist. Etiologies, indications for treatment, and restorative materials are discussed to provide guidance in planning treatment. A diagnostic decision tree is proposed for this dynamic area of restorative dentistry.

Identification and antibiotic sensitivity of bacteria isolated from periapical lesions.

Periradicular tissues from 28 refractory endodontic cases requiring surgical intervention were submitted for histological diagnosis and microbiological culture. Bacteria isolated from these lesions were identified and then tested for their antibiotic sensitivity to a panel of common antibiotics. The periapical tissue specimens of 22 out of 28 lesions (79%) contained microorganisms. Of the 22 cases showing positive growth cultures, 15 were polymicrobial and 7 were single species isolates. Fifty-three different species were recovered: 29 anaerobes, 19 facultative anaerobes, and 5 aerobes. Microbes were observed under light microscopy in only one case. The most common organisms isolated were Propionibacterium acnes, Staphylococcus epidermidis, Streptococcus intermedius, Wolinella recta, Fusobacterium species, and Clostridium species. Antibiotic susceptibility results showed no clear cut evidence of significant antibiotic resistance among the species tested. The results of this study seem to corroborate earlier studies regarding the microbial population of periapical lesions refractory to nonsurgical endodontics.

Van der Waals Epitaxial Growth of agr-Alumina Nanocrystals on Mica.

Lattice mismatch stresses, which severely restrict heteroepitaxial growth, are greatly minimized when thin alumina films are grown by means of van der Waals forces on inert mica substrates. A 10-nanometer-thick epitaxial film exhibits crystallographic sixfold symmetry, a lattice constant close to that of the basal plane [0001] of alpha-alumina (sapphire), and an aluminum: oxygen atomic ratio of 1:1.51 +/- 0.02 (measured by x-ray photoelectron spectroscopy), again the same as for bulk sapphire. The film is free of steps and grain boundaries over large areas and appears to be an ideal model system for studying adhesion, tribology, and other surface phenomena at atomic scales.

Metabolism of various carbon sources by Azospirillum brasilense.

Azospirillum brasilense Sp7 and two mutants were examined for 19 carbon metabolism enzymes. The results indicate that this nitrogen fixer uses the Entner-Doudoroff pathway for gluconate dissimilation, lacks a catabolic but has an anabolic Embden-Meyerhof-Parnas hexosephosphate pathway, has amphibolic triosephosphate enzymes, lacks a hexose monophosphate shunt, and has lactate dehydrogenase, malate dehydrogenase, and glycerokinase. The mutants are severely deficient in phosphoglycerate and pyruvate kinase and also have somewhat reduced levels of other carbon enzymes.

[Infectious endocarditis of the heart valves and valvular prostheses. report of 21 cases]. / Endocarditis infecciosa de válvulas cardíacas y prótesis valvulares. reporte de 21 casos.

During 1978, and 1979, the Surgery Division of The Cardiology and Pneumology Hospital of The National Medical Center (Mexican Institute for Social Security), studied and treated surgically twenty one cases -- in twenty patients -- of infectious endocarditis. Nine patients had an active infection in the heart valves and twelve in the prosthesis. The survival rate of the first group was 88.88% and of the second group 58.33%. The causes of death were due to the hemodynamic damage that the valvular or prosthetic dysfunction leads to, when there is a delay in the arrival of the patient to a medical unit of third level. The conventional medical treatment applicable to a reduced number of cases whose characteristics are discussed do not operate when dealing with patients with infected prosthesis or valve infections caused by non-gram positive bacteria. We conclude that this problem demands a better approach, principally surgical, to improve the prognosis of these patients.

Endocarditis infecciosa de valvulas cardiacas y protesis valvulares. Reporte de 21 casos. / Infectious endocarditis of heart valves and prothesis. Report of 21 cases

La division de Cirurgia del Hospital de Cardiologia y Neumologia del Centro Medico Nacional del Instituto Mexicano del Seguro Social durante los anos 1978 1979 estudio y trato quirurgicamente veintiun casos -en 20 pacientes- de endocarditis infecciosa. Se hace el analisis de ellos porque el grupo reune pacientes con infeccion activa sobre las valvulas cardiacas y a doce sobre las protesis.De las primeras la sobrevida fue 88,88% y las segundas de 85,33%. Al analizar las causas de muerte destaca el deterioro hemodinamico a que la disfuncion valvular o protesica conduce cuando existe retraso en la llegada del paciente a una unidad medica de tercer nivel, ya que el tratamiento medico convencional aplicable a un reducido numero de casos cuyas caracteristicas se discuten nos es operante cuando se trata de pacientes con protesis infectadas o infecciones causados por otros germenes que no sean gram positivos. Se concluye que este problema demanda una mayor acometividad, fundamentalmente quirurgica -para mejorar el pronostico de tan grave enfermedad