Development of a qualification standard for adhesives used in hybrid microcircuits

Improved qualification standards and test procedures for adhesives used in microelectronic packaging are developed. The test methods in specification for the Selection and Use of Organic Adhesives in Hybrid Microcircuits are reevaluated versus industry and government requirements. Four electrically insulative and four electrically conductive adhesives used in the assembly of hybrid microcircuits are selected to evaluate the proposed revised test methods. An estimate of the cost to perform qualification testing of an adhesive to the requirements of the revised specification is also prepared

Potential biomedical applications of ion beam technology

Electron bombardment ion thrusters used as ion sources have demonstrated a unique capability to vary the surface morphology of surgical implant materials. The microscopically rough surface texture produced by ion beam sputtering of these materials may result in improvements in the biological response and/or performance of implanted devices. Control of surface roughness may result in improved attachment of the implant to soft tissue, hard tissue, bone cement, or components deposited from blood. Potential biomedical applications of ion beam texturing discussed include: vascular prostheses, artificial heart pump diaphragms, pacemaker fixation, percutaneous connectors, orthopedic pros-thesis fixtion, and dental implants

Status of a five-centimeter-diameter ion thruster technology program

Prototype auxiliary propulsion subsystem with isolated single tank propellant feed system and 5-cm-diameter ion thruste

Stagnant Loop Syndrome: A Rare Cause of Severe Malabsorption

Background: Intestinal bacterial overgrowth as a consequence of postsurgical anatomical abnormalities as well as other small bowel diseases can lead to malabsorption. Case Report: A female patient had several abdominal operations due to recurrent intestinal obstructions. Initially, she presented with severe megaloblastic anaemia. Subsequently, she suffered from weight loss, diarrhoea, oedema, recurrent anaemia (despite vitamin B12 substitution), and severe malabsorption of proteins, lipids, iron, and vitamins. Vague information about the performed surgeries, an anatomy of the bowel that was difficult to interpret, and an unusual cholestasis made it difficult to reach the diagnosis of bacterial overgrowth due to a stagnant loop syndrome. Treatment with antibiotics only temporarily improved the condition of the patient. After restoring bowel continuity and after the resection of an enteroenteric fistula as well as of a bowel conglomerate, the patient did not show any further symptoms. Conclusion: The history of this patient indicates that the diagnosis of a stagnant loop syndrome may be difficult. The primary goal regarding surgically created small intestinal bacterial overgrowth should be the correction of the underlying small intestinal abnormality, whenever possible

Numerical Analysis of a New Mixed Formulation for Eigenvalue Convection-Diffusion Problems

A mixed formulation is proposed and analyzed mathematically for coupled convection-diffusion in heterogeneous medias. Transfer in solid parts driven by pure diffusion is coupled with convection-diffusion transfer in fluid parts. This study is carried out for translation-invariant geometries (general infinite cylinders) and unidirectional flows. This formulation brings to the fore a new convection-diffusion operator, the properties of which are mathematically studied: its symmetry is first shown using a suitable scalar product. It is proved to be self-adjoint with compact resolvent on a simple Hilbert space. Its spectrum is characterized as being composed of a double set of eigenvalues: one converging towards −∞ and the other towards +∞, thus resulting in a nonsectorial operator. The decomposition of the convection-diffusion problem into a generalized eigenvalue problem permits the reduction of the original three-dimensional problem into a two-dimensional one. Despite the operator being nonsectorial, a complete solution on the infinite cylinder, associated to a step change of the wall temperature at the origin, is exhibited with the help of the operator’s two sets of eigenvalues/eigenfunctions. On the computational point of view, a mixed variational formulation is naturally associated to the eigenvalue problem. Numerical illustrations are provided for axisymmetrical situations, the convergence of which is found to be consistent with the numerical discretization

Wie viel Arbeit macht die Aufzucht von Ökologischen Junghennen? Arbeitwirtschaftlicher Vergleich der konventionellen und ökologischen Aufzucht von Legehennen

Organic pullets are reared with daylight and are not beak-trimmed. Therefore, certain provisions are needed in order to prevent feather-pecking and cannibalism. Respec-tive guidelines are set by the German Organic Associations. It was the goal of this study to investigate whether the higher rearing standards are associated with an increased labour demand compared to conventional rearing systems. Using a ques-tionnaire, data from 32 hen-houses (10 conventional and 6 organic barn systems, 10 conventional and 6 organic aviary systems) about duration and number of working procedures were collected and exemplary models calculated. Total labour demand was between 2.36 and 7.37 worker`s hours/100 pullets. It did not differ between or-ganic and conventional rearing when comparing similar flock sizes, but were partly differently allocated to the different working procedures. On average, organic farms had smaller flocks, and there was a large influence of flock size on labour demand with small houses requiring most labour per hen. Also aviaries were more labour demanding than barn systems, but were usually associated with higher flock sizes. Our results indicate that improved pullet rearing that allows the birds to perform their natural behaviour more completely, does not necessarily cause higher labour re-quirements

Effects of substrate annealing on the gold-catalyzed growth of ZnO nanostructures

The effects of thermal substrate pretreatment on the growth of Au-catalyzed ZnO nanostructures by pulsed laser deposition are investigated. C-plane sapphire substrates are annealed prior to deposition of a thin Au layer. Subsequent ZnO growths on substrates annealed above 1,200°C resulted in a high density of nanosheets and nanowires, whereas lower temperatures led to low nanostructure densities. Separate Au film annealing experiments at 700°C showed little variation in the size and density of the Au catalyst droplets with substrate annealing temperature. The observed variation in the density of nanostructures is attributed to the number of surface nucleation sites on the substrate, leading to a competition between nucleation promoted by the Au catalyst and surface nucleation sites on the rougher surfaces annealed below 1,200°C