Strain ageing in welded joints of API5L X65Q seamless pipes

In this work, we investigated the effects of the phenomenon of strain ageing in joints obtained by gas-shielded arc welding (gas metal arc welding, GMAW), of seamless pipes of API5L X65Q steel. Test specimens obtained from the welded joints were submitted to cold plastic strain of 3% and then aged for 1 h at 250 °C, so as to induce static ageing. For evaluating dynamic ageing, the test specimens were strained to 3% and loading was maintained for 1 h at 250 °C. The aged specimens were submitted to tensile testing and representative samples were examined in the light microscope and the scanning electron microscope. It was observed that the phenomenon altered the volume fraction of secondary constituents in the weld metal and in the HAZ, with increase in the proportion of ferrite–carbide aggregates. Regarding the mechanical properties, it was found that the phenomenon reduced the elastic ratio of the welded joints due to an increase in the ultimate strength, besides increasing the total elongation, but without impairing the tensile properties of the welded joints. On comparing static ageing with dynamic ageing, it was observed that the increase in the capacity for plastic strain of the welded joints was greater after static strain ageing.     

Low pressure ethylene oligomerization with a nickel-PÔ complex

Summary The oligomerization of ethylene catalyzed by nickel-PÔ complexes at room temperature and low pressure (5 to 30 bar) yields butenes, hexenes and octenes. The molecular weight distribution can be manipulated by variation of ethylene pressure and by addition of triphenylphosphine. An unexpected linear dependence between the growing factor of the Schulz-Flory type distribution and the pressure has been observed. The equation: =6.2 (PPh₃/Ni)^1.2-[0,17 P(PPh₃/Ni)^1.2] allows to predict the composition of the -olefins formed under different reaction conditions.     

Financial time series prediction using polynomial pipelined neural networks

This paper proposes a novel type of higher-order pipelined neural network: the polynomial pipelined neural network. The proposed network is constructed from a number of higher-order neural networks concatenated with each other to predict highly nonlinear and nonstationary signals based on the engineering concept of divide and conquer. The polynomial pipelined neural network is used to predict the exchange rate between the US dollar and three other currencies. In this application, two sets of experiments are carried out. In the first set, the input data are pre-processed between 0 and 1 and passed to the neural networks as nonstationary data. In the second set of experiments, the nonstationary input signals are transformed into one step relative increase in price. The network demonstrates more accurate forecasting and an improvement in the signal to noise ratio over a number of benchmarked neural networks.     

Data Mining in Cancer Research [Application Notes]

Advances in cancer medicine have traditionally come from detailed understanding of biological processes, later translated into therapeutic interventions, whose effectiveness is established by rigorous analysis of clinical trials. Over the last two decades the increasing throughput of data from microarray screening, spectral imaging and longitudinal studies are turning the understanding of cancer pathology into as much a data-based as a biologically and clinically driven science, with potential to impact more strongly on evidence-based decision support moving towards personalized medicine [1].     

Response surface methodology applied to the enzymatic synthesis of galacto-oligosaccharides from cheese whey

In this study, a strategy was proposed for making galacto-oligossaccharides (GOS), a high valueadded product, from a byproduct of the dairy industry, cheese whey, using a commercial β-galactosidase from Kluyveromyces lactis (Lactozym® 3000L). The effects of the substrate concentration, temperature, and enzyme dosage were statistically studied and their optimum combinations were determined using response surface methodology. The increase in lactose concentration, temperature, and enzyme concentration favored a transgalactosylation reaction. The maximum values for GOS concentration (119.8 mg/mL) and yield (29.9%) in a 4 h process were obtained in the reaction system, composed of 400 mg/mL of lactose and 10 U/mL of enzyme at 40°C. Under these conditions, the lactose conversion was 68.7%. The maximum value for lactose conversion (87.8%) was observed at the same temperature and enzyme concentration, although the lactose level was 20%.     

Typological classification of clayey raw materials for ceramics manufacture, in the Tábua region (central Portugal)

Mapping of clay resources in the Cenozoic deposits of the Tábua region (central Portugal) has been carried out, together with the chemical, mineralogical and technological characterization of seventeen clay samples. The study was undertaken to relate the lithostratigraphic units and the typology of raw materials with regard to the manufacture of ceramics. The sedimentary succession comprises two units with different suitability for the manufacture of ceramics: an upper unit, with clays that present technological restrictions; and a lower unit with a much greater potential. A small set of parameters has been identified which differentiate the typological units. These parameters allow a realistic estimation to be made of the ceramic properties of any clay layer sampled in the study area. It is anticipated that with minor field work and sampling, the typological column can also be used in adjacent areas.     

Solutioning and Aging of MAR-M247 Nickel-Based Superalloy

Despite the existence of previous studies on the heat treatment of the MAR-M247 superalloy, there is a lack of microstructural characterization data that support the heat-treatment conditions that are proposed in this study. Thus, the aim of this study is to investigate the changes in microstructure that occur in this alloy when subjected to different solutioning and aging heat treatments. Thermodynamic calculations and differential thermal analysis guided the experimental design and the analysis of experimental results. The MAR-M247 superalloy was produced via vacuum induction melting and investment casting. The samples were solutioned between 1185 and 1270 °C and aged between 770 and 980 °C. The as-cast and heat-treated samples were characterized using scanning electron microscopy in backscattered electron and secondary electron modes. Thermodynamic calculations have shown that the minimum solutioning temperature is approximately 1220 °C, occurring in a γ + MC + MB₂ three-phase field (M = metal). The samples were solutioned at 1250 °C for 310 min before aging heat treatment. During solutioning the carbide composition is the MC phase shifts to higher hafnium (Hf) and lower tantalum (Ta) content, which is in agreement with the thermodynamics calculations. After solutioning, residual aluminum (Al) segregation leads to the formation of large γ′ particles in certain regions of the material following one-step aging heat treatment at 770 and 870 °C. However, a nearly uniform size distribution of γ′ particles was observed after aging at 980 °C as well as after double aging heat treatment at 980 °C for 300 min + 870 °C for 1200 min.     

Freshwater Plants Synthesize Sulfated Polysaccharides: Heterogalactans from Water Hyacinth (Eicchornia crassipes)

Sulfated polysaccharides (SP) are found mainly in seaweeds and animals. To date, they have only been found in six plants and all inhabit saline environments. Furthermore, there are no reports of SP in freshwater or terrestrial plants. As such, this study investigated the presence of SP in freshwaters Eichhornia crassipes, Egeria densa, Egeria naja, Cabomba caroliniana, Hydrocotyle bonariensis and Nymphaea ampla. Chemical analysis identified sulfate in N. ampla, H. bonariensis and, more specifically, E. crassipes. In addition, chemical analysis, FT-IR spectroscopy, histological analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA), as well as agarose gel electrophoresis detected SP in all parts of E. crassipes, primarily in the root (epidermis and vascular bundle). Galactose, glucose and arabinose are the main monosaccharides found in the sulfated polysaccharides from E. crassipes. In activated partial thromboplastin time (APTT) test, to evaluate the intrinsic coagulation pathway, SP from the root and rhizome prolonged the coagulation time to double the baseline value, with 0.1 mg/mL and 0.15 mg/mL, respectively. However, SP from the leaf and petiole showed no anticoagulant activity. Eichornia SP demonstrated promising anticoagulant potential and have been selected for further studies on bioguided fractionation; isolation and characterization of pure polysaccharides from this species. Additionally in vivo experiments are needed and are already underway.     

Partial Logistic Artificial Neural Network for Competing Risks Regularized With Automatic Relevance Determination

Time-to-event analysis is important in a wide range of applications from clinical prognosis to risk modeling for credit scoring and insurance. In risk modeling, it is sometimes required to make a simultaneous assessment of the hazard arising from two or more mutually exclusive factors. This paper applies to an existing neural network model for competing risks (PLANNCR), a Bayesian regularization with the standard approximation of the evidence to implement automatic relevance determination (PLANNCR-ARD). The theoretical framework for the model is described and its application is illustrated with reference to local and distal recurrence of breast cancer, using the data set of Veronesi (1995).