Probing the wurtzite conduction band structure using state filling in highly doped InP nanowires

We have grown InP nanowires doped with hydrogen sulfide, which exhibit sulfur concentrations of up to 1.4%. The highest doped nanowires show a pure wurtzite crystal structure, in contrast to bulk InP which has the zinc blende structure. The nanowires display photoluminescence which is strongly blue shifted compared with the band gap, well into the visible range. We find evidence of a second conduction band minimum at the gamma point about 0.23 eV above the band edge, in excellent agreement with recent theoretical predictions. Electrical measurements show high conductivity and breakdown currents of 10(7) A/cm(2).     

The effect of size of sub-sample on mineral analysis values of apple fruits

Apple fruits were divided into opposite sectors of different sizes, and the mineral analyses of the sectors were compared with whole fruit values. Opposite sectors as small 8-12% of whole fruit weight were found to be as representative as larger sectors. There was no evidence of either a constant or a proportional bias arising as a result of sub-sampling. Sub-sampling variation was greater for Ca than for N, P, K and Mg.     

Change of milk yield with clinical diseases for a high producing dairy herd

Changes in milk production associated with occurrence of clinical diseases (dystocia, stillbirth, twin births, milk fever, retained placenta, displaced abomasum, limping due to foot lesions, metritis, ketosis, and mastitis) were investigated. Data were collected daily on 388 lactation. Stepwise least squares regression was used to evaluate existence of associations between diseases and six yield measures that characterized milk production in the first 119 d postpartum. Logistic regression was used to investigate whether milk yield 1 to 5 d in milk might be of use to detect cows with early postpartum metritis (less than 21 d after calving). Lower milk production to 5 d postpartum was associated with an increased risk of early postpartum metritis in the logistic regression model. Yield to 5 and to 21 d postpartum was lower in cases of stillbirth, retained placenta, and early postpartum metritis. Yield from 22 to 49 d postpartum remained lower in cows diagnosed with early postpartum metritis. Milk yield losses occurred during diagnosis and treatment of displaced abomasum and mastitis. Ketosis was associated with yield losses prior to and at treatment. Ketosis to 21 d in milk was also associated with lower production after treatment. Limping diagnosed in the first 49 d postpartum coincided with higher yield to 5 d, to 21 d, and after 49 d postpartum.     

Impact of preheating on the behavior of Listeria monocytogenes in a broth that mimics Camembert cheese composition

The effect of preheating on the survival of L. monocytogenes in Richard's broth, which mimics the composition of Camembert cheese composition, was examined. Experiments were carried out to reproduce contamination of cheese with environmental heat-stressed cells of L. monocytogenes surviving hot-cleaning procedures. Cells in mid-log phase were heated for 30 min at 56 degrees C before being inoculated into Richard's broth. The pHs and temperatures of Richard's broth were chosen to recreate the conditions of curd dripping (pH 5, 25 degrees C), of the beginning of cheese ripening (pH 5, 12 degrees C), and of the beginning (pH 5, 4 degrees C) and the end (pH 7, 4 degrees C) of cheese storage. Immediately after heat treatment, the viability loss was especially high for strain 306715, which exhibited only 0.6% +/- 0.2% survival, compared with 22% +/- 8.7% for strain EGD. The percentages of the surviving heated cells that were injured were 93% +/- 8% for strain 306715 and 98% +/- 3% for strain EGD. The destruction of the surviving L. monocytogenes cells was accelerated when they encountered the pH and temperature conditions of Camembert cheese during manufacturing, ripening, and cold storage (pH 5 at 25, 12, and 4 degrees C, respectively). The multiplication of the surviving heated cells was retarded under favorable growth conditions similar to those of storage by the distributor and the consumer (pH 7 at 4 and 12 degrees C, respectively).     

Quinones As Additives During Soda Cooking

Anthraquinone-1-acetic acid is a less effective delignification catalyst than anthraquinone but it gives an enhanced carbohydrate stabilization by converting reducing sugar end groups more effectively to aldonic acid end groups. This reaction produces the hydroquinone form of the additive which is then easily oxidized by oxygen at 80°C. Oxygen treatment favors the end group stabilization. Depolymerization of the cellulose is suppressed by the presence of magnesium hydroxide but cannot be avoided completely.     

Behavior Of Calcium,Magnesium and Manganese Compounds During Oxygen Bleaching of Kraft Pulps

During oxygen bleaching of kraft pulps manganese compounds can, depending on their amounts, the charges of sodium hydroxide and of magnesium protector, and on the presence of trace amounts of catalytically active transition metals retard or promote the depolymerization of the cellulose. The present report deals with pulps pretreated with 2 % nitrogen dioxide. As shown in forthcoming papers similar results were obtained with pulps without pretreatment with nitrogen compounds.

Pretreatment with nitrogen dioxide at 80°C followed by washing with water removed about 95 % of the magnesium and manganese from kraft pulps. Subsequent oxygen bleaching for 180 min removed 40–90 % of the calcium remaining in the pretreated pulps. Produced hydroxycarboxylate ions gave rise to low molecular complexes of calcium and of magnesium, added as protector. Competition for complexing ligands contributed to a decreased dissolution of calcium with increasing addition of magnesium. When magnesium was applied large amounts of colloids of polynuclear magnesium species were produced. These contained lignin fragments and less abundant metal compounds such as manganese and calcium.

Wet oxidation of both low molecular complexing agents and of organic fragments of larger size contributed to a decreased or unchanged concentration of low molecular metal complexes and metal compounds linked to the colloids with hydrated magnesium oxide as the main constituent. The conditions which favored the wet oxidation were similar to those which led to an increased attack on the lignin and carbohydrates in the fibers and thus promoted the dissolution of low molecular metal complexes and the formation of metal ions containing colloids. Under certain conditions precipitation of sparingly soluble manganese compounds of oxidation states higher than +2 had a predominant influence on the concentration of manganese in the liquor.     

Thermal malfunction criteria of fire safety electrical equipment in nuclear power plants

Malfunctions of nuclear power plants' (NPP) fire safety electrical equipment may be the consequence of a fire, leading to an increase of temperature and heat fluxes in a room and its adjacent ones. Electrical equipment manufacturers issue a so‐called ‘maximum temperature of normal operation’ under which a continuous function is guaranteed. However, this manufacturer temperature does not correspond to the notably higher real maximum operating temperature. Exactly knowing this temperature has two impacts: adequate selection of fire safety equipment and new fire probabilistic risk assessment (PRA) damage threshold. Those levels are today very conservative for performance‐based design: 40°C for electronic boards and 55°C for electromechanical materials. That is why Electricité de France, Research and Development Division (EDF R&D), performed several tests in the MILONGA facility to investigate the thermal malfunction levels of cabinet equipment classified as ‘Important for Safety’ by

• first defining what malfunction means, according to the material type and its required function;
• defining a relevant and reliable methodology of tests;
• testing a sample of electromechanical materials and electronic boards used in NPP and
• suggesting new temperature criteria for Fire PRA.

Although the equipment behaviour may be dependent upon the materials of construction and equipment layout, the main results are the malfunction temperatures of 130°C for electromechanical materials and 95°C for electronic boards. Copyright © 2012 John Wiley & Sons, Ltd.     

Plasma Etch Processes for Embedded FRAM Integration

We describe the etch processes used for integration of embedded ferroelectric random access memory (FRAM) within a standard CMOS logic flow. The ferroelectric module is inserted following front-end contact formation and prior to backend integration using only two additional mask levels: capacitor pattern and bi-level via pattern. The single-mask stack etch process employs a TiAlN hardmask to define Ir/IrO_x/PZT/IrO_x/Ir capacitors. Protective sidewalls can be formed using an etchback process. The bi-level via etch and subsequent metal fill processes complete the FRAM module formation. Functional 4 MB arrays embedded with 5 levels of Cu/FSG integration have been demonstrated.     

Preferential Interface Nucleation: An Expansion of the VLS Growth Mechanism for Nanowires

A review and expansion of the fundamental processes of the vapor–liquid–solid (VLS) growth mechanism for nanowires is presented. Although the focus is on nanowires, most of the concepts may be applicable to whiskers, nanotubes, and other unidirectional growth. Important concepts in the VLS mechanism such as preferred deposition, supersaturation, and nucleation are examined. Nanowire growth is feasible using a wide range of apparatuses, material systems, and growth conditions. For nanowire growth the unidirectional growth rate must be much higher than growth rates of other surfaces and interfaces. It is concluded that a general, system independent mechanism should describe why nanowires grow faster than the surrounding surfaces. This mechanism is based on preferential nucleation at the interface between a mediating material called the collector and a crystalline solid. The growth conditions used mean the probability of nucleation is low on most of the surfaces and interfaces. Nucleation at the collector‐crystal interface is however different and of special significance is the edge of the collector‐crystal interface where all three phases meet. Differences in nucleation due to different crystallographic interfaces can occur even in two phase systems. We briefly describe how these differences in nucleation may account for nanowire growth without a collector. Identifying the mechanism of nanowire growth by naming the three phases involved began with the naming of the VLS mechanism. Unfortunately this trend does not emphasize the important concepts of the mechanism and is only relevant to one three phase system. We therefore suggest the generally applicable term preferential interface nucleation as a replacement for these different names focusing on a unifying mechanism in nanowire growth.     

Uranium Superconductivity Redux

Since the discovery of heavy-fermion superconductivity in uranium compounds in the early 1980s, other uranium compounds have been discovered that are fully as interesting to study. However, as we look forward in the year 2000, we now have higher-purity, single crystals of the element itself. Preliminary resistivity and ac susceptibility measurements show the improved quality of the samples and thus hold the promise of understanding many aspects of its superconductivity, which have remained untouched for almost 25 years.