Friedel-Crafts acylations with modified clays as catalysts

Friedel-Crafts acylations are very effectively catalyzed by clays modified through exchange of the interlamellar cations or through impregnation of metal chlorides. The acidic K10 montmorillonite exchanged with iron(III) gives outstanding results in quantitative (98–100%) acylation of anisole (15 min), mesitylene (15 min), and p-xylene (3 h) at 140–160 °C. Clays impregnated with zinc chloride, such as the K10 montmorillonite, or Japanese acidic clay show near-equivalent catalytic performance.     

Entwicklungsstand und Anwendungsfelder von Nachhaltigkeitskennzahlen für die Stahlindustrie

Applicability of sustainability indicators — List of IISI — Summarizing considerations — Sustainability as a strategic leadership element by balanced score card — Sustainability management in the materials’ industry     

The effect of particle shape on the activity of nanocrystalline TiO2 photocatalysts in phenol decomposition

Nanosized TiO₂ photocatalysts were synthesized via hydrogen–air flame hydrolysis. X-ray diffraction (XRD) measurements revealed that the TiO₂ samples thus prepared consisted mainly of anatase (79–98 wt%) and the rest is rutile. Average particle diameters from TEM measurements were found to vary between 48 and 63 nm. The specific surface area of the samples was found to be practically independent of the synthesis parameters employed (20–32 m² g⁻¹). Photocatalytic activity of the catalysts was studied by using various model compounds. In spite of their very similar properties, the initial decomposition rate of phenol and methanol showed up to threefold variations within the series of the samples, and it was significantly higher for the best catalyst than that determined for Degussa P25. Our TEM measurements demonstrated that in the less active catalysts the dominant morphology of the particles is spherical, while polyhedral (cubic or hexagonal) shapes predominate in the samples with superior photocatalytic activity. From these observations, we concluded, that the shape of the primary particles (both in the case of our home made ones and in various batches of Degussa P25) strongly influence the photocatalytic activity of titania nanoparticles.     

A genetic algorithm that exchanges neighboring centers for k-means clustering

We present a genetic algorithm for selecting centers to seed the popular k-means method for clustering. Using a novel crossover operator that exchanges neighboring centers, our GA identifies superior partitions using both benchmark and large simulated data sets.     

Metadata-driven optimal transcoding in a multimedia proxy

An adaptive multimedia proxy is presented which provides (1) caching, (2) filtering, and (3) media gateway functionalities. The proxy can perform media adaptation on its own, either relying on layered coding or using transcoding mainly in the decompressed domain. A cost model is presented which incorporates user requirements, terminal capabilities, and video variations in one formula. Based on this model, the proxy acts as a general broker of different user requirements and of different video variations. This is a first step towards What You Need is What You Get (WYNIWYG) video services, which deliver videos to users in exactly the quality they need and are willing to pay for. The MPEG-7 and MPEG-21 standards enable this in an interoperable way. A detailed evaluation based on a series of simulation runs is provided.     

Correlation of chromatographic absolute loss determinations with the A.O.C.S. Cup Refining method in soybean oil

Summary It can be concluded, on the basis of our experiments, that chromatographic loss determinations can be well correlated with A.O.C.S. Cup Refining determinations. This correlation is good for samples above 1% chromatographic losses and somewhat less accurate for samples below 1.0%. Most of the discrepancy in correlation is inherent in the Cup Loss method because it is less precise in general than the chromatographic determination. On the other hand, the chromatographic loss is an accurate, easily obtainable index for unavoidable losses resulting from the nonneutral oil fraction of the oils. In the majority of cases the degumming of the oil to levels below 1% chromatographic loss is not indicated by a parallel decrease in cup losses. Thus, in these cases, as long as premiums are paid on the basis of the A.O.C.S. Cup Loss method, the processor is placed in a very disadvantageous position. It should be pointed out that all our determinations were made on the oils from the 1956 crop during the summer months. The possibility that different crop years will result in different correlation curves might exist, and we are planning to do further work in the future. It is hoped that by presenting statistically significant figures on this subject, enough interest will be stimulated for more collaborative work, which might result in a review of the industry's present method for the determination of refining losses in soybean oil.     

A new method for quantitative determination of BHA

A qualitative test developed by Laszlo has been adapted to the quantitative determination of BHA. The determination is based on measurement of the specific and sensitive color resulting from reaction of BHA with diazotized sulfanilic acid in alkaline solution. The red-purple color, which is stable for long periods, has an absorption maximum at 535 mμ. Beer’s law is obeyed, and a concentration range of 0.0001% to 0.01% BHA may be measured. The method requires careful adjustment of antioxidant-reagent ratios for rapid and maximum color development, The optimum ratios, the effect of alcohol, and interfering substances are diseussed. The method, as described, also provides for an accurate specific determination of BHA in fats and oils even when other antioxidants are present. Journal Pager No. 184, American Meat Institute Foundation. Presented at 50th Anniversary Meeting, American Oil Chemists’ Society, April 20–22, 1959, New Orleans, La. Chemist in the Division for Inspection of Animal Products (D.I.P.O.A.) of the Ministry of Agriculture (Rio de Janeiro, Brazil) and American Association of University Women Fellow at the American Meat Institute Foundation during 1958–59.     

New image analysis methods for the study of mixing patterns in stirred tanks

A method of treating data acquired with the planar laser‐induced fluorescence technique has been developed to visualize the topology of two‐dimensional concentration fields and to describe the dynamics of the coherent mixing structures identified. This method is based on a conditional binary transformation of the local concentration data, combined with a joint probability calculation. The methodology has been used to investigate the mixing in a stirred tank, at two injection port locations (in the bulk and in the impeller stream region). With bulk injection, a “folding phenomenon” of the coherent mixing structure was detected. Away from this port, large‐scale spatially periodic motion was identified, with a characteristic time of oscillation of the order of 2 to 3 s. With injection in the impeller stream region, no spatial instabilities of the coherent structure were detected. Local oscillations of the coherent mixing structure were found both on short and long time‐scales (i.e., ?1 and ?80 s).     

High-Density Real-Time PCR-Based in Vivo Toxicogenomic Screen to Predict Organ-Specific Toxicity

Toxicogenomics, based on the temporal effects of drugs on gene expression, is able to predict toxic effects earlier than traditional technologies by analyzing changes in genomic biomarkers that could precede subsequent protein translation and initiation of histological organ damage. In the present study our objective was to extend in vivo toxicogenomic screening from analyzing one or a few tissues to multiple organs, including heart, kidney, brain, liver and spleen. Nanocapillary quantitative real-time PCR (QRT-PCR) was used in the study, due to its higher throughput, sensitivity and reproducibility, and larger dynamic range compared to DNA microarray technologies. Based on previous data, 56 gene markers were selected coding for proteins with different functions, such as proteins for acute phase response, inflammation, oxidative stress, metabolic processes, heat-shock response, cell cycle/apoptosis regulation and enzymes which are involved in detoxification. Some of the marker genes are specific to certain organs, and some of them are general indicators of toxicity in multiple organs. Utility of the nanocapillary QRT-PCR platform was demonstrated by screening different references, as well as discovery of drug-like compounds for their gene expression profiles in different organs of treated mice in an acute experiment. For each compound, 896 QRT-PCR were done: four organs were used from each of the treated four animals to monitor the relative expression of 56 genes. Based on expression data of the discovery gene set of toxicology biomarkers the cardio- and nephrotoxicity of doxorubicin and sulfasalazin, the hepato- and nephrotoxicity of rotenone, dihydrocoumarin and aniline, and the liver toxicity of 2,4-diaminotoluene could be confirmed. The acute heart and kidney toxicity of the active metabolite SN-38 from its less toxic prodrug, irinotecan could be differentiated, and two novel gene markers for hormone replacement therapy were identified, namely fabp4 and pparg, which were down-regulated by estradiol treatment.