Clinical experience with AVE Micro Stent. Results of the implantation of 204 stents

To assess the efficacy and safety of the AVE Micro Stent, we deployed 204 stents in 144 consecutive patients during a one year period. Indications for stenting were acute closure in 3.4%, dissection in 5.4%, post balloon pTCA restenosis in 3.4%, non-favorable result in 16.7% and de novo in 71.1%. Patient population included 39 (27%) patients with stable angina, 86 (59.7%) with unstable angina, 16 (11.1%) with acute MI and 3 (2.1%) with cardiogenic shock. Angiographic lesion morphology were as follows: type A, 17.7%, type B1, 42.1%; type B2, 16.2%; type C, 24%. Procedural success was obtained in 204 of 205 attempted stents (99.5%) and clinical success was 93.1%. Oral anticoagulation was not routinely used. Enzymatic elevation consistent with myocardial necrosis occurred in 3.2% with Q wave MI in 0.7%. Three patients (2.1%) had bleeding at site of femoral puncture with one requiring transfusion and surgery. Mortality was 0.8% in the angina group, 6.25% in the MI group and one of the 3 patients with cardiogenic shock died and represents the only apparent stent thrombosis as she experienced sudden death one week after successful left main stenting. We conclude that high success rates can be obtained with the AVE Micro Stent due to it's excellent trackability, adequate radio-opacity and relative flexibility.     

Development of enzyme-loaded nanoparticles: effect of pH

Enzyme superoxide dismutase (SOD) incorporation parameters were evaluated after immobilization in polyisobutylcyanoaclylate (PIBCA) nanoparticles. After initialization of the anionic mechanism of polymerization, pH was increased and its effect on the characteristics of PIBCA nanoparticles analysed. Our goal included optimization of enzyme activity during incorporation into nanoparticles and the influence on size distribution. Unloaded nanoparticles were not significantly affected by the pH increase. At pH 3 the size distribution indicates a bimodal distribution: 58 nm (63%) and 146 nm (37%). When pH was increased to 5 after 1 h of polymerization the size distribution is: 57 nm (70%) and 125 nm (30%). When pH was increased to 5, after 2 h of polymerization, the size distribution is 67 nm (56%) and 160 nm (44%). Meanwhile, the retention of activity of SOD in polymerization medium is 49% at pH 3, and 98% at pH 5. The effect of pH increase from 3 to 5, after 1 h of polymerization, on the characteristics of loaded nanoparticles is an increase of retention of enzyme activity (18 to 30%); and the evidence of a pH-dependent smaller size population of loaded nanoparticles. In fact at pH 3 the size distribution is 83 nm (15%), 195 nm (15%), 440 nm (70%) and when pH is increased from 3 to 5 the size distribution becomes 55 nm (30%); 170 nm (30%); 430 nm (40%).This paper was accepted for publication after the 1995 Conference of the European Society of Biomaterials, Oporto, Portugal, 10–13 September.     

Creep behavior of ingot and powder metallurgy 6061Al

The creep behavior of 6061Al alloy obtained by ingot metallurgy and powder metallurgy, IM and PM, respectively, has been investigated in the context of published studies on this alloy. The behavior of the IM alloy in a given range of temperatures where the β, Mg₂Si, precipitates are formed, is dominated by dislocation climb-controlled creep and aluminum self-diffusion as rate controlling process. A dependence of the β inter-particle distance, λ, with the applied stress, σ, of the form is found when the creep data are analyzed in the context of the sub-structure invariant model. The superior creep resistance of the PM material can be explained if a threshold stress, σ₀, is brought into the creep equation. This term is the difference between the applied stresses needed to reach a given strain rate in the PM and the IM alloys, and correlates well with a particle–dislocation interaction mechanism according to the Artz–Wilkinson model.     

The self-assembled nanophase particle (SNAP) process: a nanoscience approach to coatings

In the corrosion protection of aluminum-skinned aircraft, surface pretreatment and cleaning are critical steps in protecting aerospace alloys from corrosion. Our recent discovery of a revolutionary new method of forming functionalized silica nanoparticles in situ in an aqueous-based sol–gel process, and then crosslinking the nanoparticles to form a thin film, is an excellent example of a nanoscience approach to coatings. This coating method is called the self-assembled nanophase particle (SNAP) process.

The SNAP coating process consists of three stages: (1) sol–gel processing; (2) SNAP solution mixing; (3) SNAP coating application and cure. Here, we report on key parameters in the ‘sol–gel processing’ and the ‘coating application and cure’ stages in the GPTMS/TMOS system. The SNAP process is discussed from the formation of the nanosized macromolecules to the coating application and curing process.

The ‘sol–gel processing’ stage involves hydrolysis and condensation reactions and is controlled by the solution pH and water content. Here, the molar ratio of water to hydrolysable silane is a key factor. SNAP solutions have been investigated by NMR, IR, light scattering, and GPC to identify molecular condensation structures formed as a function of aging time in the solution. In moderate pH and high water content solutions, hydrolysis occurs rapidly and condensation kinetic conditions are optimized to generate nanophase siloxane macromolecules.

In the ‘SNAP solution mixing’ stage, crosslinking agents and additives are added to the solution, which is then applied to a substrate by dip-coating to form the SNAP coating. The chemical structure and morphology of the films have been characterized using X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (TOF-SIMS) and atomic force microscopy (AFM). SNAP films are amorphous but exhibit nanostructured assembly of siloxane oligomers at a separation of about 1.8 nm as well as molecular level ordering of O–Si–O species. The surface analytical data indicate that the films retain the basic chemical arrangement of the siloxane macromolecules/oligomers and crosslinking process creates a network of siloxane oligomers tethered together. Results of these analyses are then used to construct a model of the SNAP coating. Results of these analyses are discussed in detail.     

老油田注CO2并埋存的技术-经济模拟

随着技术的发展和工具的利用，石油工业将有助于减少大气中温室气体的排放。将CO2作为一种提高原油采收率（EOR）的试剂注入到油藏中有双重好处。除了通过称作CO2埋存的技术将CO2在油藏中储存数千年以避免它进入大气之外，这种技术还可以提高用自然方法不可能再采出的采油量。CO2埋存包括从人为源中捕获气体，压缩并输送到油田。本文描述了一种技术一经济方法来评估这一过程在一个假定老油田的可行性。它除了考虑主要组成的敏感性分析，比如，收益，投资，经营成本，税（根据巴西财政制度）和碳信用额（此项目挣到的，1个碳信用额等于1吨CO2），还考虑了一个现金流模型。该方法考虑了量化的排放量和该过程中所用的能量，重点是对环境的技术贡献。     

Effects of a mechanical stimulation of localization of annexin-like proteins in Bryonia dioica internodes

Mechanical stimulation exerted by rubbing a young internode of Bryonia dioica plants inhibits its growth. Previous cellular and biochemical studies showed that this growth inhibition is associated with Ca(2+) redistribution and profound modifications of plasma membrane characteristics. We extracted and purified Ca(2+)-dependent phospholipid-binding proteins from B. dioica internodes. Two main proteins, p33 and p35, and other minor bands were isolated and identified as annexin-like proteins because of their biochemical properties and their cross-reactions with antibodies against maize (Zea mays L.) annexins. Rabbit antiserum was obtained by injection of B. dioica p35. This antiserum was used for the immunocytolocalization of annexin-like proteins in internode parenchyma cells. It appeared that the distribution of annexin-like proteins was different before and 30 min after the mechanical stimulation. Western analysis of proteins in membrane fractions after separation by free-flow electrophoresis showed that p35 was present in most fractions, whereas p33 appeared mainly in plasmalemma-enriched fractions after the mechanical stimulation. It is hypothesized that a subcellular redistribution of these proteins might be involved in growth inhibition by mechanical stress.     

In situ AFM study of potassium oleate adsorption and calcium precipitate formation on an apatite surface

This study investigates the effect of ionic strength on the adsorption of potassium oleate in apatite surfaces in situ by atomic force microscopy (AFM). Natural apatite crystals were equilibrated with calcium nitrate solutions in the presence and absence of potassium oleate (4 × 10⁻³ M). AFM images for each experiment along with their histograms were recorded. The contact AFM mode allowed visualizing the topography of the surfaces with the formation of adsorbed layers and calcium dioleate colloids. The presence of calcium ions in aqueous solution (2 × 10⁻⁴ M) led to the formation of precipitated calcium carbonate/hydroxide, as evidenced in the histogram. Oleate adsorption, in the presence of high ionic strength, occurs through the formation of clusters of calcium dioleate, observed in both 2D and 3D micro-topography. The presence of these clusters makes the apatite surface heterogeneous and rough, thus influencing its flotability.     

Neural networks applied to service life prediction of exterior painted surfaces

Service life prediction is assuming a primary role as it allows a more rational use of scarce resources; its methods are useful for defining preventive maintenance plans, thereby increasing performance and reducing costs. A new mathematical model is presented that uses artificial neural networks to evaluate the service life of painted surfaces. The data on facade degradation were collected from field observations on 160 buildings (220 painted surfaces) in Lisbon, Portugal, examining several degradation agents. In service conditions, the mean estimated service life of exterior painted surfaces is found to be 9.49 years, with a standard deviation of 0.633 years. Detailed factors are identified and incorporated into the model, which account for variations in degradation. Some statistical parameters are used to evaluate the validity and efficiency of the model. The values obtained are consistent with the existing perception relative to the durability of painted coatings. These values can be used to evaluate the economic and environmental performance of painted surfaces throughout their life cycle. The use of this model can optimize inspection and maintenance plans as well as the implementation of inform decisions at the design and construction stages.     

Total antioxidant capacity of meat and meat products consumed in a reference ‘Spanish standard diet’

The antioxidant capacity (AC) of meat, meat products and the comparison with fish, vegetable products, milk and a balanced and healthy diet was determined using the ORACFL assay. The hydrophilic ORACFL (H‐ORACFL) of hake and sardine was 596 ± 133 and 641 ± 128 μmol Trolox Equivalents (TE) per 100 g, respectively. The highest H‐ORACFL value was found in cured meat samples, where Iberian cured ham (4890 ± 443 μmol TE per 100 g), whereas the lowest level of 797 ± 68 μmol TE per 100 g was found in Frankfurt sausages. Products like mortadela with olives, sobrasada and salami showed intermediate values ranging between 1107 ± 123 μmol TE per 100 g and 1011 ± 63 μmol TE per 100 g. Iberian cured ham presents the higher AC of all meat products studied, and this value being higher than that provided by red wine (3135 ± 312 μmol TE per 100 g). The AC of orange juice was lower than meat products, with the exception of Frankfurt sausages. Finally, the estimated total antioxidant capacity (TAC) of the reference standard diet was 29 006 μmol TE per intake whole diet per day, and meat representing 10.51% per intake per day of the TAC of the whole diet.