Procedures to check the adjoint equations when using the method of steepest ascent

The method of steepest ascent is well documented in the literature [1]. However, its application to problems of high order (over 20) is not straightforward [2]. One problem that arises in the application of the method of steepest ascent, particularly to problems of high order and generally to problems of any order, is the pinpointing of errors in programming or in deriving the adjoint equations. This correspondence presents a systematic method for pinpointing such errors. First, a derivation of equations pertinent to the method of steepest ascent as developed by Bryson et al. [1] is presented. Then checks on the adjoints are followed by an illustrative example of the use of these checks.     

Structural features of linear alkylbenzene sulfonates as observed in13C magnetic resonance spectra

Fourier-transform¹³C{¹H nuclear magnetic resonance spectroscopy of the internally substituted phenylhexadecanes and theirpara-sulfonates has been done as a part of a general study of alkylaryl sulfonates thought to be of significance in complex surfactants, such as the petroleum sulfonates and various synthetic products. The systematics of structural variations and their effects on observed chemical shifts of specific carbon atoms is detailed with the aim of developing rapid, nondestructive methods of analysis of complex mixtures of both hydrocarbons and hydrocarbon sulfonates. Advantages and restrictions of the¹³C spectrometric method are illustrated in the case of a mixture of alkylbenzene sodium sulfonates typical of a synthetic surfactant.     

A transformer for measuring 60 Hz loss and critical current characteristics of short superconductor tapes

To test samples of superconductor tape destined for use in power transmission cables, it is necessary to simulate the actual operating conditions for these cables. A transformer in which the field parallel to one side of the superconductor sample is provided by cylindrical iron poles, produces these conditions quickly and efficiently.The design of this transformer is described together with the actual measurement techniques used to assess the performance of samples.     

Identification of trail pheromone of the antTetramorium caespitum L. (Hymenoptera: Myrmicinae)

The trail pheromone of the antTetramorium caespitum L. is a 7030 mixture of 2,5-dimethylpyrazine and 3-ethyl-2, 5-dimethylpyrazine. The average total amount of the two pyrazines present in the poison vesicle was found to be 3.9 ng per ant, of which 2.7 ± 0.4 ng is 2,5-dimethylpyrazine and 1.15 ±0.25 ng is 3-ethyl-2,5-dimethylpyrazine. The pyrazines constitute only 0.03% of the volume of the poison vesicle but account for the whole of the trail-following activity. A 7030 mixture of the respective pyrazines evoked the highest activity in artificial trail-following tests.     

Magnetoplumbite related barium aluminates

Yet new complexities are indicated in the structural details of the barium “hexa”-aluminates, in a burgeoning family of magnetoplumbites with many different types of possible defect structures.     

Mitochondrial multiplex real-time PCR as a source tracking method in fecal-contaminated effluents

Multiplex real-time PCR amplifying fecal mitochondrial DNA (mtDNA) combined with rapid, crude DNA preparations are promising additions to surface water source tracking methods. Amplification of eukaryotic mitochondrial DNA identifies the fecal source directly and can be used in conjunction with other intestinal microbial methods to characterize effluents. Species-specific primers and dual-labeled probes for human, swine, and bovine NADH dehydrogenase subunit 5 (ND5) genes were created for multiplex real-time PCR in feces and effluent slurries. The linear range of the multiplex assay was 10(2)-10(7) mtDNA copies for human, bovine, and swine effluent in combination (equal volumes). PCR amplification efficiencies for bovine, human, and swine mtDNA when assayed in combination were 93, 107, and 92% respectively. Linear regression correlation coefficients (r2) were 0.99 for all standard curves except for human mtDNA in combination (r2 = 0.95). Multiplex amplification of bovine, human, and swine mtDNA (ND5) exhibited no cross-reactions between the effluents from three species of interest. Also, no cross-reactions were observed with effluents of other vertebrates: sheep, goat, horse, dog, cat, Canada goose, broiler, layer, turkey, and tilapia. Performed as a blind test, the PCR operator was able to correctly identify all but two effluent challenge samples (10/12 or 83% correct) with no false positives (22/22 or 100% correct). The multiplex assay had a tendency to detect the species of highest mtDNA concentration only. Better detection of all three species in a combination of human, bovine, and swine effluents was accomplished by running each real-time PCR primer/ probe set singly. Real-time PCR detection limit was calculated as 2.0 x 10(6) mitochondrial copies or 0.2 g of human feces per 100 mL effluent. Some carry-over mtDNA PCR signal from consumed beef, but not pork, was found in feces of human volunteers.     

The Oxidative Precipitation of Thallium at Alkaline pH for Treatment of Mining Influenced Water

Thallium (Tl) may exceed regulatory limits in mining-influenced water (MIW) associated with processing cadmium, copper, gold, lead, and zinc ores. It is a toxic metal that is soluble over a wide pH range, resulting in both persistence in the environment and poor removal by conventional lime precipitation. This study evaluated the effect of potassium permanganate (KMnO₄) at alkaline pH on Tl removal from MIW in batch experiments. The oxidation of Tl⁺ to Tl³⁺ by KMnO₄ and subsequent Tl removal was explored at Tl concentrations of ≤1 mg/L in synthetic and actual MIW. In addition to Tl, the synthetic MIW contained ≈5 mg/L of Mn, while the actual MIW contained >10 mg/L of Al, Cu, Fe, Mn, and Zn and had a pH ≈ 2.5. Dissolved Tl <2 μg/L in synthetic MIW was achieved at a pH ≈ 9 (CaO addition) and ≥5 mg/L of KMnO₄. In the actual MIW, dissolved Tl <2 μg/L was achieved at pH ≈ 9 and ≥12 mg/L of KMnO₄. The Tl removal mechanism is complicated due to the presence of reduced Mn in the synthetic MIW and multiple metals in the actual MIW. However, effective Tl removal was achieved by adding KMnO₄ to synthetic and actual MIW at alkaline pH.