Gel permeation chromatography applied to the study of the nitrohumic acids from coal

Gel permeation chromatography on Sephadex (G-types) was applied to nitrohumic acids (NHA) from lignites. Deionized water and TRIS (Tris-hydroxymethylaminomethane) buffer were tested as eluents. Deionized water provided the same number of fractions and better resolution than TRIS. In both cases, interactions between the gel matrix and the NHA occurred. Five NHA fractions were obtained and characterized by elemental and spectral analysis, which showed significant differences between them. Molecular weights of the fractions, calculated from Cameron's calibration for soil humic acids, are < 9000 or > 100 000 with no significant fractions having molecular weights in the range 9000–100 000.     

Phase I-II study of multiple daily fractions for palliation of advanced head and neck malignancies

PURPOSE: To assess palliation of advance head and neck malignancies with the use of rapid hyper fractionation studies similar to the RTOG 85-02. MATERIALS AND METHODS: 37 patients with 39 lesions were entered into the non-randomized Phase I-II protocol, between 1984 and 1991. Previously untreated malignancies were present in 24 lesions, primary recurrent diseases in six patients, metastasis to the head and neck in five patients and skin primaries in the remaining two cases. At presentation 15 of 37 patients (or 17 of 39 lesions) were in operable due to poor medical status, eight patients were considered technically in operable due to extent of disease, 10 patients had distant metastasis and four patients refused surgery. The protocol uses twice a day fraction (370 cGy per fraction) for 2 consecutive days totalling 1,480 cGy per course. Three courses were given at 3-week intervals for a final tumor dose of 4,440 cGy in twelve fraction over 8-9 weeks. RESULTS: Eleven of 39 lesions had complete response; 19 lesions had partial response; 4 lesions had no response; 3 lesions progressed under treatment. Response could not be assessed in two patients. The average survival after completion of therapy was 4.5 months ranging from 2 weeks to 31 months. Palliation was achieved in 33 of 39 lesions. The acute reactions were minimal and no late or long term complications were noted. CONCLUSION: The absence of significant complications with reasonable response in the high rate of palliation suggests that this rapid hyper fractionation palliation study should be studied for further evaluation.     

Sinus aspergillosis after an endodontic treatment. Presentation of a clinical case

Aspergillosis is an opportunistic deep mycosis that occurs in immunocompromised patients, often in the paranasal sinuses. However, it sometimes occurs in healthy subjects, producing symptoms similar to those of a chronic sinusitis that is unresponsive to conventional treatment. A possible entry point for Aspergillus is the oroantral communication originated by perforation of the dental root cavity during root canal of a molar with penetration of material. We report the clinical case of a patient with symptoms of chronic sinusitis who was diagnosed as sinus aspergillosis after radiological and histological study. The origin may have been a third upper molar in which a root canal was performed.     

The influence of sepiolite on the dynamic moduli and thermal transition of compatible and incompatible blends based on poly(vinylidene fluoride)

This paper reports on a study of dynamic moduli and thermal transitions of poly(vinylidene fluoride) in compatible blends with poly(methylmethacrylate) and in non-compatible blends with polystyrene. The effects of sepiolite on the compatibility of these blends have been studied.     

What is coefficient alpha? An examination of theory and applications.

Psychological research involving scale construction has been hindered considerably by a widespread lack of understanding of coefficient alpha and reliability theory in general. A discussion of the assumptions and meaning of coefficient alpha is presented. This discussion is followed by a demonstration of the effects of test length and dimensionality on alpha by calculating the statistic for hypothetical tests with varying numbers of items, numbers of orthogonal dimensions, and average item intercorrelations. Recommendations for the proper use of coefficient alpha are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DESORPTION WITH CHEMICAL REACTION IN CONTACTING DEVICES

Chemical processes where a gas is absorbed into a liquid and reacts to give a product that desorbs back into the gas are quite common in the industry. In this study, the reaction between the absorbed gaseous reactant and a nonvolatile reactant is considered to be slow, fast or instantaneous, while the volatile product may react further in a slow reaction. Effects of various operating parameters such as the liquid and gas flow rates, the gas-liquid interfacial area and the coefficients for mass transfer are examined. Situations can arise where the absorbing gas reacts but the product diffuses completely to the bulk of the liquid, and the rate of desorption is null. The expressions presented here define conditions to avoid this situation and allow the calculation of the optimal design and operation of the gas-liquid contacting device     

Beitr?ge zur Kenntnis mexikanischer Drogen, Pflanzen und Nahrungsmittel. XVI. Mitteilung. Verteilung der Aminos?uren im e?baren Anteil der Krabbe(Peneus setiferus L.)

Zusammenfassung Nach der Methode vonvan Slyke wurde eine Aufteilung der AminosÄuren im eßbaren Anteil der in mexikanischen Gewässern häufigen KrabbePeneus setiferus L. vorgenommen.Cf. Tesis, Universidad Nacional Autonoma de Mexico 1952.Vorhergehende Mitteilungen erschienen in Materiae Vegetabiles.Anschrift: c/o. Carlo Erba de Mexico, Mexico 21, D. F.     

Viewers' responses to delays in simulated teletext reception

In a teletext service, information is retrieved from a sequence of pages broadcast cyclically on a video channel and the mean and variance of system response times are directly related to the number of pages in the cycle. Two experiments were conducted to investigate the maximum tolerable range of such delays. Three degrees of negative viewer response were defined by progressively more conservative criteria for annoyance. Results showed that both the proportion of delays noticed and the proportion of negative viewer responses at each criterion increased linearly with the square root of the system response time. As an example of the effect of criterion, 50 per cent of observers were slightly annoyed or worse with a mean response time of approximately 13s, while 20 per cent were moderately annoyed or worse with the same delay. In limiting the duration of the broadcast cycle, teletext service providers apparently should consider what proportion of viewers to annoy and to what degree.     

Heat transfer analysis of cheese cooling incorporating uncertainty in temperature measurement locations: Model development and validation

Successful modelling of the thermal behaviour of food products requires accurate knowledge of both the thermal properties of the product and the cooling media to which it is exposed to and a correct approach to validation of the model output against experimental temperature histories. This procedure is complicated where there is uncertainty in the location at which temperature is measured in the product. The cooling of a soft cylindrical cheese product that is partially immersed in brine and air is examined. As the cheese is very deformable, it is not possible to exactly identify the measurement location of the temperature-recording thermocouples. The Uniform and Exponential probability distributions were found to best represent the variability in thermocouple location at the centre and surface of the product, respectively. Expressions for the mean measured temperature at the centre and surface that result from the distributed nature of thermocouple location were obtained. These expressions were used to derive equivalent locations in the cheese which should be used when comparing model and experimental temperature predictions. The theoretical approach was also checked against Monte Carlo simulations and there was excellent agreement between them. It was shown that when validating model temperature histories against experimental readings that this phenomenon must be taken into account.