Ferrihydrite in water wells and bacterial enrichment cultures

The chemical and mineralogical composition of Fe(III)-precipitates formed in water wells and laboratory cultures was examined. Ferrihydrite, a poorly ordered Fe(III)-oxide of bulk formula 5Fe₂O₃ · 9H₂O, was detected by X-ray diffraction analysis in all samples. The crystallinity varied from one sample to another. Fe was the only major element detected by energy-dispersive X-ray spectrometry; several other elements were present at minor levels reflecting the chemical composition of the medium. The results suggest that the biologically-catalyzed iron encrustation of water wells begins with the initial formation of ferrihydrite.     

Editorial: A new beginning for the journal.

Announces that the International Journal of Stress Management has a new publisher--The Educational Publishing Foundation of the American Psychological Association. The editor discusses what this means for the readership and focus of the journal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute wound failure

The causes and treatment of acute failure of the abdominal incision are reviewed, along with a summary of studies on fascial healing. Emphasis is placed on taking large bites of tissue during closure to prevent dehiscence. Patient-related risk factors are viewed as less important in the causation of wound failure.     

Liquid chromatographic determination of methylxanthines and catechins in herbal preparations containing guaraná

Herbal preparations derived from the dried seeds of guaraná (Paullinia cupana) have become a popular nutritional supplement used for stimulatory purposes. Once considered a drug substance in the United States, guaraná currently is classified as a food additive and dietary supplement. The pharmacological activity of guaraná-containing products is primarily due to methylxanthine alkaloids. For guaraná preparations, methylxanthine levels and, more significantly, the presence of several polyphenol compounds (i.e., catechins) provide phytochemical markers of authenticity. Methylxanthines and polyphenols are extracted from sample matrix with a heated phosphate buffer-methanol solution, the cooled extract is filtered, and the extract is injected into the liquid chromatographic (LC) system. A Nova-Pak C18 column eluted with phosphate buffer-methanol mobile phase (pH = 3.50) and monitored at 272 nm gave satisfactory resolution for the methylxanthines theobromine, theophylline, caffeine and the polyphenols (+)-catechin and (-)-epicatechin. Twenty-four products including dried seeds, dried paste, seed powders, tablets, and capsule formulations were assayed and conclusions were drawn about their authenticity. The LC system responded linearly to methylxanthines over the 100-fold range in concentration from 0.043 to 4.30 micrograms/mL for theobromine and caffeine and from 0.041 to 4.10 micrograms/mL for theophylline. Precision data for the 3 methylxanthines obtained from 10 different products (n = 5) gave relative standard deviation (RSD) values of 1.18-15.52% within a concentration range of 0.01-52.28 mg/g. Recoveries of methylxanthines from fortified products varied from 87.5 to 120.0%. The response for catechins was linear over a 200-fold range in concentration of 0.05-10.0 micrograms/mL. Precision data from 5 products (n = 5) gave RSD values of 1.08-5.54% within a concentration range of 0.34-32.65 mg/g. Recoveries from these products ranged from 87.7 to 109.7%. Results and chromatographic profiles for 14 commercial products in solid dosage form indicate that a number of these products may not contain authentic guaraná as an active ingredient or contain less than the declared quantity of guaraná. The proposed procedure also was applied to 2 carbonated soft drinks and a sample of maté.     

Book review: Psychology: The Science of Behaviour.

Review of the book, Neil R. Carlson, William Buskist, Michael E. Enzle, and C. Donald Heth (authors) Psychology: The Science of Behaviour. Toronto, Ontario: Pearson Education Canada Ltd., 2002, 701 pp., ISBN 0-13-0393606-6. Reviewed by: George Alder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and understanding science instructional material.

Learning and understanding of science instructional material was examined from a cognitive load perspective. It was suggested that instructions can be difficult to learn if multiple elements of information need to be simultaneously processed through limited working memory. Diagrams were expected to reduce cognitive load by allowing students to process information using fewer elements in working memory than an equivalent text-based format. However, if instructional information could be processed serially, then working-memory load should be light, and both diagrammatic and text-based instructions were hypothesized to be equally effective. Two experiments using different chemistry instructions confirmed these hypotheses and so highlight the role of cognitive load factors in instructional design. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strategy guidance and memory aiding in learning a problem-solving skill.

Guidance can help learners overcome the difficulties of getting started in a novel domain, but it is often ineffective in promoting learning and transfer. This article examines two aspects of guidance--communicating solution strategies for a problem domain and providing working memory support--in learning a novel problem-solving skill. Subjects in two experiments learned to troubleshoot simulated information networks. The learning environment varied in type of guidance provided--none, variable template, fixed template, and procedural instruction--and in availability of memory aiding. Variable-template guidance was effective when memory aiding was provided, and procedural instructions produced effective learning with or without memory aiding. However, fixed-template guidance was not effective, and there was no consistent effect of memory aiding in unguided, discovery learning conditions. The results have theoretical implications for the locus of guided-learning effects and suggest practical guidelines for the design of guided-learning environments.     

A Motivational First-year Electronics Lab Course

An elective laboratory course has been developed at Rensselaer Polytechnic Institute to motivate freshmen for further study of engineering in general and to spur interest in electrical and computer engineering in particular. The course philosophy is that hands-on laboratory and design experiences build student confidence, stimulate curiosity, and demonstrate the relevance of engineering work — thereby increasing motivation and retention. This paper describes the structure of the new course and reports on the evaluation results, which confirm that carefully structured hands-on experience is an effective way of motivating freshmen. Evaluation results also indicate that the course has increased student creativity and confidence. Since the lab course is just one credit, it appears possible to address the motivation problem without overloading already crowded first-year engineering programs.     

Mutational activation of the Cpx signal transduction pathway of Escherichia coli suppresses the toxicity conferred by certain envelope-associated stresses

Anticipation and suspicion are critical aspects to any discussion of intrauterine adhesions. Curettage between the second and fourth week postpartum is more likely to cause adhesions than is any other endometrial trauma. Infertility, recurrent abortion, or menstrual aberrations after any uterine trauma should cause the physician to suspect the presence of intrauterine adhesions. Hysterosalpingography and hysteroscopy are the ideal methods to make the diagnosis of IUA, and the latter is the safest, least traumatic, and most precise method of treating adhesions. The addition of an intrauterine splint and high-dose estrogen therapy completes the therapeutic approach. Before attempting conception the cavity should be inspected to verify its normality.