An Autonomous Palm-Sized Gliding Micro Air Vehicle

This article has concentrated on the development of a set of core technologies key to the realization of an autonomous 2-g glider. One aspect which was not discussed in detail was the ease of construction and low cost of an individual MicroGlider. Integration is simplified through a number of rapid prototyping techniques and the low costs of most components allow rigorous testing to be done without worry of substantial damage.     

The role of office industries in development planning

Industrial Development has tended to be oriented to the attraction of manufacturing facilities. This paper discusses the trend towards service industries in the North American Economy, and the potential impact of developing office industries on a local economy. The literature on office location theory is reviewed and the results of the literature review are related to decentralization of offices to a planned new town near Metropolitan Toronto. The results of a survey of Toronto offices is presented and the results compared to that of the literature. Policy recommendations are proposed for the new town to attract office developments.     

S-adenosylmethionine metabolism and DNA methylation in hydrazine-treated rats

The treatment of rats with hepatotoxic doses of hydrazine (NH2-NH2) induces the rapid formation of 7-methylguanine and O6-methylguanine in liver DNA. The methyl moiety in these reactions might be derived from the cellular S-adenosylmethionine pool because radioactivity administered to these rats as methionine rapidly appears in the DNA as methylated guanine. An increased incorporation of radioactivity into 5-methylcytosine was previously reported followed by subsequent suppression. This increased radiolabeling of 5-methylcytosine coincided with time of maximal DNA guanine methylation. To determine the nature of S-adenosylmethionine metabolism during the period of DNA methylation induced by hydrazine treatment, and to determine if the increased radiolabeling of 5-methylcytosine at this time reflected an actual increase in 5-methylcytosine synthesis, liver DNA synthesis and S-adenosylmethionine levels and turnover were assayed. Liver S-adenosylmethionine concentrations varied slightly between control rats and hydrazinetreated rats during the first five hours after hydrazine administration, and no difference was detectable in the incorporation of administered [3H]methionine into S-adenosylmethionine. Because S-adenosylmethionine specific radioactivity in hydrazine-treated rats was not different from control rats, the previously observed increased radiolabeling of 5-methylcytosine appeared to represent an actual increase in synthesis. This conclusion was supported by finding that incorporation of radioactive thymidine into DNA was also accelerated immediately following hydrazine administration, again followed by a decrease. 5-Methylcytosine sythesis, therefore, appears to follow DNA synthesis during hydrazine toxicity, and formation of 7-methylguanine and O6-methylguanine in liver DNA of hydrazine-treated rats occurs during a short period of increased DNA sythesis and 5-methylcytosine formation very early in hydrazine toxicity.     

Lizard feeding by Leptoconops (Brachyconops) californiensis (Diptera: Ceratopogonidae) on desert sand dunes

Adult females of Leptoconops (Brachyconops) californiensis Wirth & Atchley and 1 female of Leptoconops (Holoconops) sp. near knowltoni were collected from 5 species of lizards in desert sand dune habitats in San Bernardino and Riverside counties, California, and northern Sonora, Mexico. Feeding by L. californiensis was observed on the dorsum (usually the heads) of the lizards, with up to 6 L. californiensis on a host at 1 time. The L. sp. near knowltoni appeared to be trying to feed but did not contain blood. Midges fed during calm, warm daylight periods from March through October. Reptile feeding by Ceratopogonidae is reviewed.     

Analysis of chemical intermediates from low-temperature steam gasification of biomass

A reactor system was developed to study the process of lignin and biomass gasification at low temperatures (100 °C to 350 °C) and high pressure (up to 375 atm). The reactor allowed for withdrawal of samples from either the top or bottom of the reaction environment throughout the period of the experiment while maintaining the reaction temperature and pressure. An analytical method was developed for separating and standardizing the initial decomposition products formed during steam-alkali gasification of kraft pine lignin and Douglas fir wood flour.     

A modified system for predicting σ formation

A new method is proposed for predicting the ō-phase susceptibility of high-temperature superalloys. It is based on modifications of previous methods which involve electron-vacancy correlations. A calculated critical electron-vacancy number unique to each residual matrix composition is compared to the total electron-vacancy concentration (N _V) for the residual matrix. The new method has been applied to experimentally determined residual matrix compositions (i.e. the composition of a matrix after all early precipitates have formed) of nickel-and cobalt-base superalloys. The modification exhibits a greater range of applicability to various austenitic alloy compositions than do current electron-vacancy tools. R. G. BARROWS, formerly Graduate Research Assistant, University of Denver, Denver, Colorado 80210     

Monitoring the Formation of a CH3NH3PbI3–xClx Perovskite during Thermal Annealing Using X‐Ray Scattering

Grazing incidence wide and small angle X‐ray scattering (GIWAXS and GISAXS) measurements have been used to study the crystallization kinetics of the organolead halide perovskite CH₃NH₃PbI_3–xCl_x during thermal annealing. In situ GIWAXS measurements recorded during annealing are used to characterize and quantify the transition from a crystalline precursor to the perovskite structure. In situ GISAXS measurements indicate an evolution of crystallite sizes during annealing, with the number of crystallites having sizes between 30 and 400 nm increasing through the annealing process. Using ex situ scanning electron microscopy, this evolution in length scales is confirmed and a concurrent increase in film surface coverage is observed, a parameter crucial for efficient solar cell performance. A series of photovoltaic devices are then fabricated in which perovskite films have been annealed for different times, and variations in device performance are explained on the basis of X‐ray scattering measurements.     

Effect of Ca2+ and Zn2+ on UO2 dissolution rates

The dissolution of UO(2) in a continuously stirred tank reactor (CSTR) in the presence of Ca(2+) and Zn(2+) was investigated under experimental conditions relevant to contaminated groundwater systems. Complementary experiments were performed to investigate the effect of adsorption and precipitation reactions on UO(2) dissolution. The experiments were performed under anoxic and oxic conditions. Zn(2+) had a much greater inhibitory effect on UO(2) dissolution than did Ca(2+). This inhibition was most substantial under oxic conditions, where the experimental rate of UO(2) dissolution was 7 times lower in the presence of Ca(2+) and 1450 times lower in the presence of Zn(2+) than in water free of divalent cations. EXAFS and solution chemistry analyses of UO(2) solids recovered from a Ca experiment suggest that a Ca-U(VI) phase precipitated. The Zn carbonate hydrozincite [Zn(5)(CO(3))(2)(OH)(6)] or a structurally similar phase precipitated on the UO(2) solids recovered from experiments performed in the presence of Zn. These precipitated Ca and Zn phases can coat the UO(2) surface, inhibiting the oxidative dissolution of UO(2). Interactions with divalent groundwater cations have implications for the longevity of UO(2) and the mobilization of U(VI) from these solids in remediated subsurface environments, waste disposal sites, and natural uranium ores.     

Qualitative determination of carbon black in food products

Carbon black (C.I. 77266) is an insoluble pigment produced by the partial combustion of hydrocarbons. The pigment is known by several synonyms, including vegetable carbon, lamp black and carbon ash, that correspond to the raw materials and methods used for its production. Vegetable carbon (E153) is permitted for use in colouring food in the European Union. The US Food and Drug Administration (USFDA) has not approved the use of any type of carbon black for colouring food, although the agency batch certifies the pigment as D&C Black No. 2 for use in colouring certain cosmetics. Since carbon black (as vegetable carbon) may be present in food products offered for import into the United States, the USFDA's district laboratories need a qualitative analytical method for determining its presence. We have developed an extraction method for this purpose. A sample is broken down and dissolved with nitric acid. The resulting solution is filtered and treated with hydrochloric acid to dissolve any black iron oxide also present as a colour additive. A black residue remaining on the filter paper indicates the presence of carbon black in the food. We confirmed the presence of carbon black in residues from several standards and food products using Raman spectroscopy. The limit of detection for this method is 0.0001%.