Stents in aortic coarctation. Immediate results

From September 1996 to March 1997 we implanted stents Palmaz (P-308 Johnson & Johnson) in six patients with aortic coarctation. Age ranged from 13 to 30 years (mean = 20), 3 female and 3 male. We implanted the stent without predilation. Balloon diameter was 12 mm in two cases and 15 mm in four cases for complete expansion we used 14 to 20 mm balloon diameter in five instances and in one case we used a dual balloon 15 + 15 mm. The gradient pre-stent ranged from 30 to 65 mmHg (mean = 44) and decreased to 0 mmHg in five cases and in one patient the residual gradient was 4 mmHg. Systolic aortic pressure pre-stent was 135 mmHg and decreased to 117 mmHg. There were no significant complications. In conclusion, we have demonstrated the feasibility of balloon-expandable stent implantation as a method of alleviation the obstruction in coarctation of the aorta in this group of patients. It is an excellent alternative to surgical treatment and it is better than balloon angioplasty that results in marked improvement in the angiographic appearance of the thoracic aorta. It eliminates the gradient, has minimum morbidity and no mortality, no aneurysm formation. Late restenosis and possible aneurysm formation remains an unlikely complication in view of the ample luminal diameter and the high velocity of flow.     

Determination of impurity contents in the photo-deposition processes by X-ray fluorescence

Impurity contents of photo-deposited thin films of a-Se have been measured by the X-ray fluorescence method. The impurity concentration was found lower for the photo-precipated material as compared to the reagents and to the chemical precipitate.     

Fertilization of tropical rice: A case study on Bangkok plain

This study consisted of a survey on the nutritional status of rice plants in relation to nutrient application and yield in 70 farmers' fields in four provinces of Bangkok plain during the 1977 wet season. In addition a series of fertilizer experiments were carried out on rice experimental stations in the same provinces to study yield response to N and P fertilization and to develop a fertilizer recommendation system based on plant analysis.The average grain yield in the survey was 3.2 t ha^–1 and the early (high yielding varieties), medium (local) and late maturity (local) types yielded 3.3, 2.8 and 3.0 t ha^–1, respectively. The average amount of fertilizers applied to these maturity types were 33, 15 and 7 kg N ha^–1 and 15, 8 and 6 kg P ha^–1, respectively. Regression analysis indicated only a slight correlation between yield and any level of fertilizer application. On experimental stations yields over 6 t ha^–1 were obtained with applications of N over 100 kg ha^–1 and P over 22 kg ha^–1. Evaluation of nutritional status of plants based on plant analysis showed that in all provinces there were strong and widespread nutrient deficiences primarily of N and secondarily of P, and possibly of some other nutrients. Fertilizer application based on plant analysis gave high yield responses. It was concluded that the major constraints of yield on Bangkok plain are too low fertilizer application especially of N, and unbalanced fertilization of N and P.     

The effects of dietary phospholipids enriched with phosphatidylethanolamine on bile and red cell membrane lipids in humans

The role of phospholipids in biliary cholesterol solubilization and crystallization has only recently begun to be appreciated. Phospholipid vesicles are believed to be the metastable carrier from which cholesterol nucleates. Cholesterol crystallization is influenced by the phospholipid species in bile. Feeding rats and hamsters with diets enriched in phospholipids or their precursors, especially ethanolamine, resulted in reduced cholesterol saturation of bile. Although whole phospholipids are normal dietary constituents, the effects and safety of phospholipid components have not been tested in humans. In the present study, we have evaluated the effects of a dietary phospholipid mixture, enriched with phosphatidylethanolamine, on human bile and red blood cell membrane lipid composition. Five ambulatory volunteers having a chronic indwelling T-tube, with an intact enterohepatic circulation, were investigated. Thirty-six grams of phospholipids (54% phosphatidylethanolamine, 54% linoleyl acyl chains) were added to their daily diet for fourteen days. Biliary nucleation time, cholesterol carriers, as well as plasma, red blood cell membrane, and bile lipid compositions, were monitored. Following phospholipid supplementation, the proportion of linoleyl chains (18:2) in biliary phospholipids increased significantly from 31.1±1.2 to 37.7±5.3%, while that of oleyl chains (18:1) decreased from 11.4±1.6 to 9.6±1.1%. These changes were accompanied by an increase of linoleate and its metabolite, arachidonate, in red cell membranes. Phospholipid feeding did not cause any side effects, and no significant changes in biliary nucleation time, cholesterol, phospholipid, or bile salt concentrations, or in the distribution of cholesterol within micelles or vesicles. We conclude that phospholipid feeding is safe, and can be effective as a vehicle for lecithin fatty acyl chain modulation of bile and lipid membranes. These findings may provide a basis for a controlled modulation of biliary phospholipids to increase cholesterol solubility in bile.     

Parameter analysis of a practical lithium- and sodium-air electric vehicle battery

For electric vehicles (EV) having a 500 km range between charges, there is a need to develop smaller and lower-cost batteries. Lithium-air has the potential to deliver a step change in the specific energy of rechargeable lithium batteries. In order to develop a practical, safe, smaller and lower-cost lithium and sodium-air rechargeable EV battery it is necessary to eliminate the formation of dendritic deposits (on charge), increase the current density up to 100 mA cm⁻² (or reducing cell DC resistance to less than 10 Ω cm²) and change the oxygen-discharge product from peroxide to oxide. We suggest here a novel concept, namely to replace the metallic lithium anode by liquid sodium and to operate the sodium-oxygen cell above the sodium melting point (97.8 °C). In this report we studied the deposition-dissolution process of sodium in polymer electrolytes at 105 °C and we present, for the first time, preliminary results that demonstrate the feasibility of running a liquid-sodium-oxygen cell with polymer electrolytes at above 100 °C.     

On commutativity based Edge Lean search

The problem of state space search is fundamental to many areas of computer science, such as, e.g., AI and formal methods. Often, the state space to be searched is huge, so optimizing the search is an important issue. In this paper, we consider the problem of visiting all states in the setting where transitions between states are generated by actions, and the (reachable) states are not known in advance. Some of the actions may commute, i.e., they result in the same state for every order in which they are taken. We show how to use commutativity to achieve full coverage of the states, while traversing a relatively small number of edges.     

Spatial-frequency response of holographic gratings photodeposited from inorganic colloids

Surface photodeposition is a photon-assisted process by which thin films are formed on substrates immersed in colloid solutions. We experimentally evaluate the resolution capabilities of the photodeposition process with amorphous selenium colloids by recording holographic gratings at different spatial frequencies, up to 2200 lines/mm. The experimental diffraction efficiencies are analyzed in terms of a theoretical model, which relates the spatial-frequency response to optical recording parameters and colloid particle sizes. The maximal experimental diffraction efficiency reaches 13% with a spatial frequency of f = 1100 lines/mm. The diffraction efficiencies decrease monotonically with spatial frequency, and drop to half of the maximal diffraction efficiency at f ≈ 1500 lines/mm. These resolution capabilities are achieved with colloid particle sizes extending up to 80 nm. The theoretical derivation indicates that to obtain spatial frequencies above 3000 lines/mm, one should restrict the colloid particle size to a(max) ≤ 30 nm.     

On system rollback and totalized fields: An algebraic approach to system change

In system operations the term rollback is often used to imply that arbitrary changes can be reversed i.e. ‘rolled back’ from an erroneous state to a previously known acceptable state. We show that this assumption is flawed and discuss error-correction schemes based on absolute rather than relative change.Insight may be gained by relating change management to the theory of computation. To this end, we reformulate previously-defined ‘convergent change operators’ of Burgess into the language of groups and rings. We show that, in this form, the problem of rollback from a convergent operation becomes equivalent to that of ‘division by zero’ in computation. Hence, we discuss how recent work by Bergstra and Tucker on zero-totalized fields helps to clear up long-standing confusion about the options for ‘rollback’ in change management.     

Three-dimensional thin-film Li-ion microbatteries for autonomous MEMS

Autonomous MEMS require similarly miniaturized power sources. In this paper, we present the first working three-dimensional (3-D) rechargeable Li-ion thin-film microbattery technology that is compatible with MEMS requirements. The technology has been developed, and full 3-D cells have been manufactured on both glass and silicon substrates. Our 3-D microbatteries have a sandwich-like structure of conformal thin-film electrodes, electrolyte and current collectors. The films are deposited sequentially on all available surfaces of a perforated substrate (e.g., silicon or a glass microchannel plate or "MCP") using wet chemistry. The substrate has thousands of high-aspect ratio holes per square cm, thereby providing more than an order of magnitude increase in surface area per given footprint (original 2-D substrate area). The full 3-D cell consists of a Ni cathode current collector, a MoO/sub y/S/sub z/ cathode, a hybrid polymer electrolyte (HPE) and a lithiated graphite anode that also serves as anode current collector. One 3-D cell with a roughly 1-/spl mu/m-thick cathode ran at C/10 to 2C charge/discharge rates and room temperature for 200 cycles with 0.2% per cycle capacity loss and about 100% Faradaic efficiency. The cell exhibited a capacity of 2 mAh/cm/sup 2/, about 30times higher than the capacity of a similarly built planar (2-D) cell with the same footprint and same cathode thickness.