An X-ray absorption spectroscopy study of Mo oxidation in Pb at elevated temperatures

The corrosion of fuel cladding and structural materials by lead and lead-bismuth eutectic in the liquid state at elevated temperatures is an issue that must be considered when designing advanced nuclear systems and high-power spallation neutron targets. In this work, lead corrosion studies of molybdenum were performed to investigate the interaction layer as a function of temperature by X-ray absorption spectroscopy. In situ X-ray absorption measurements on a Mo substrate with a 3-6 μm layer of Pb deposited by thermal evaporation were performed at temperatures up to 900 °C and at a 15° angle to the incident X-rays. The changes in the local atomic structure of the corrosion layer are visible in the difference extended X-ray absorption fine structure and the linear combination fitting of the X-ray absorption near-edge structure to as-deposited molybdenum sample and molybdenum oxide (MoO₂ and MoO₃) standards. The data are consistent with the appearance of MoO₃ in an intermediate temperature range (650-800 °C) and the more stable MoO₂ phase dominating at high and low temperatures.     

Application of Hyphenated Chromatography–Mass Spectrometry Techniques to Plant Allelopathy Research

Plant allelopathy offers hope as an additional means of weed control in modern agriculture. Its mechanisms and molecular basis are not yet well understood. Research on the chemical basis for allelopathy has often been hindered by the complexity of plant and soil matrices, making it difficult to track active compounds. Recent improvements in the cost and capabilities of bench-top chromatography–mass spectrometry instruments make these tools more powerful and more widely available to assist with molecular studies conducted in today's expanding field. Such instrumental techniques are herein recommended as economically efficient means of advancing the rigor of allelopathy research and assisting the development of a better understanding of the chemical basis for the allelopathy phenomenon.     

Manipulating the taste-related composition of strawberry fruits (Fragaria × ananassa) from different cultivars using deficit irrigation

Demand and, consequently, production of strawberry fruits has increased over the past few years and, as a result, the water abstractions for cultivation of this fruit have risen considerably. To limit the amounts of water used for several horticultural crops, water deficit irrigation (DI) has been seen as a potential alternative for new cultivation systems. DI in strawberry fruits is generally associated with reduction in berry size and yield; however, a recent study demonstrated that DI on strawberry can increase the concentration of some taste- and health-related compounds in fruits from cv. Elsanta. Hence, the aim of the present study was to further corroborate such findings and to assess the response (and variability) among different strawberry cultivars (namely Christine, Elsanta, Florence, Sonata and Symphony) to imposed water-DI conditions. Water-DI affected both fruit physiology and biochemistry. Nevertheless, the response to drought stress was different for each of the cultivars tested. Plants from cvs. Elsanta, Sonata and Symphony showed a greater reduction in berry size, accompanied by a significant increase in dry matter content for fruit harvested from DI-treated plants. Concomitant to this, and where dry matter was increased, the concentrations of sugars and some acids were generally higher in DI-derived fruit. In contrast, cvs. Florence and Christine did not show significant variations in berry weight or any of the target analytes measured when grown under the conditions imposed in this study. The results presented herein suggest that reducing water irrigation between flower initiation and fruit harvest may be a viable technique for increasing the concentrations of taste-related compounds in cvs. Elsanta, Sonata and Symphony and it may not have a negative impact on overall fruit size of cvs. Christine and Florence.     

SELECTING A TEMPERATURE TIME HISTORY FOR PREDICTING FATIGUE LIFE OF MICROELECTRONICS SOLDER JOINTS

Temperature cycling tests are standard industry practice for determining the thermomechanical fatigue life of solder joints. Industry-standard temperature profiles usually start from room temperature, then go to a high temperature, then to a cold temperature, and then back to room temperature. In addition, most of the time, the temperature profile contains dwell times at the highest and lowest temperatures. The dwell time at a high temperature corresponds to the on-state storage of the device, and the cold-temperature dwell time simulates the off-state storage of the device. In this study, the actual temperature history of a Ball Grid Array (BGA) package in a laptop computer was measured in situ. Experimental reliability studies were conducted using the in situ measured temperature history as well as industry-standard temperature history. This article presents the influence of temperature history on solder joint fatigue life. In order to measure deformations in the solder joint under cycling loading, a new Moire interferometry grating replication technique was developed to be able to measure strain field during fatigue testing.     

Dynamic modelling and control of fully rated converter wind turbines

Today, many countries are integrating large amount of wind energy into the grid and many more are expected to follow. The expected increase of wind energy integration is therefore a concern particularly to transmission grid operators. Based on the past experience, some of the relevant concerns when connecting significant amount of wind energy into the existing grid are: fault ride through requirement to keep wind turbines on the grid during faults and wind turbines have to provide ancillary services like voltage and frequency control with particular regard to island operation.While there are still a number of wind turbines based on fixed speed induction generators (FSIG) currently running, majority of wind turbines that are planned to be erected are of variable speed configurations. The reason for this is that FSIG are not capable of addressing the concern mentioned above. Thus, existing researches in wind turbines are now widely directed into variable speed configurations. This is because apart from optimum energy capture and reduction of mechanical stress, preference of these types is also due to the fact that it can support the network such as its reactive power and frequency regulation. Variable wind turbines are doubly fed induction generator wind turbines and full converters wind turbines which are based on synchronous or induction generators.This paper describes the steady state and dynamic models and control strategies of wind turbine generators. The dynamic models are presented in the dq frame of reference. Different control strategies in the generator side converter and in the grid side converter for fault ride through requirement and active power/frequency and reactive/voltage control are presented for variable speed wind turbines.     

Action as a Fast and Frugal Heuristic

Decision making is usually viewed as involving a period of thought, while the decision maker assesses options, their likely consequences, and his or her preferences, and selects the preferred option. The process ends in a terminating action. In this view errors of thought will inevitably show up as errors of action; costs of thinking are to be balanced against costs of decision errors. Fast and frugal heuristics research has shown that, in some environments, modest thought can lead to excellent action. In this paper we extend this work to situations in which action is taken after little or no thought. We show that these `highly active' or `decision cycles' processes can lead to excellent results at the cost of almost no thought. The paper examines the settings in which this effectiveness is possible, and lists a number of environmental features that are required for decision cycles to work well. Several research directions for analytical, laboratory, and field-based research are identified.     

Prodrugs for targeting hypoxic tissues: regiospecific elimination of aspirin from reduced indolequinones

We report the cases of three patients with anorexia nervosa (AN) who each recovered rapidly after experiencing a life-threatening episode with severe thrombocytopenia. All three cases were the typical restricting-type of AN, occurring in adolescence. They refused to be admitted to a hospital until their general condition had been severely deteriorated. Their lowest platelet counts were 2.9, 4.6, and 2.3 x 10(4)/mm3, respectively. Apparent hemorrhagic tendencies, such as purpura, gingival and nasal bleeding, and gastrointestinal bleeding were observed. The bone marrow examination showed apparent hypoplasia in two patients. No evidence of disseminated intravascular coagulation or autoantibody to platelets was detected. The platelet counts recovered rapidly by water and nutritional supplementation. The recovery from the AN itself was excellent in all three patients without specific psychotherapy.