Kinetic study of enzymatic urea hydrolysis in the pH range 4-9

The enzymatic hydrolysis of urea by jack bean urease was investigated at 25degreesC over the pH range 4-9. Reaction rate data were found to be well described by a modified Michaelis-Menten equation with a pH-dependent rate coefficient and a product inhibition term. The influence of pH on activity was interpreted in terms of perturbation of the enzyme distribution among three differently protonated forms. Kinetic analysis yielded a Michaelis constant of 3.21 mmol l(-1) and indicated that the inhibition mechanism was of the fully non-competitive type, with K-P = 12.2 mmol l(-1). The estimated activation energy was 35.3 kJ mol(-1). The resulting kinetic expression was tested by comparing model predictions with the experimental behaviour observed in unbuffered media and over a long-teen period

Carbon monoxide concentrations evaluated by traffic noise data in urban areas

It is shown that variations in carbon monoxide concentrations can be evaluated by measuring environmental noise, wind velocity and vertical Thermal stability. The results can be justified on the basis of the theory of the street canyon effect. The methodology proposed was verified in two Italian cities with different characteristics: Milan and Ravenna

A Report on the 2012–13 Composition and Rhetoric Category of the MLA Job Information List

As part of rhetmap.org’s experiment mapping the Composition and Rhetoric (C/R) category of the Modern Language Association (MLA) Job Information List (JIL), we present the following summary of the 2012–13 job market season. Rhetmap.org scraped the MLA JIL C/R data once a week from September 2012 to July 2013. By the first week of July, 2013 there were approximately 282 listings posted. Of those listings, 205 were posted by December 31, 2012 or in the first four months of the 2012–13 job market. In the next four sections we have broken down the C/R into four categories: geography, type of institution (two-/four- year), rank of position advertised, and job titles. Download the PDF here or view the report below. We welcome your feedback and insights in the comments below or on twitter via the hashtag #rhetmap

'Making it count': incentives, student effort and performance

This paper examines how incentives to participate in online assessments (quizzes) affect students’ effort and performance. Our identification strategy exploits within-student weekly variation in incentives to attempt online quizzes. We find tournament incentives and participation incentives to be ineffective in increasing quiz participation. In contrast, making the quiz counts towards the final grade substantially increases participation. We find no evidence of displacement of effort between weeks. Using a natural experiment which provides variation in assessment weighting of the quizzes between two cohorts, we find that affected students obtain better exam grades. We estimate the return to 10% assessment weighting to be around 0.27 of a standard deviation in the in-term exam grade. We find no evidence that assessment weighting has unintended consequences, i.e., that increased quiz effort: displaces effort over the year; reduces other forms of effort; or reduces (effort and thus) performance in other courses. Finally, assessment weighting induced effort increases most for students at and below median ability, resulting in a reduction of the grade gap by 17%

Reaction between quinone and thiazolidine. A study on the formation mechanism of new antiproliferative quinolindiones

Reaction between quinolinquinone and thiazolidine in basic medium was investigated. 2-Arylthiazolidine-4-carboxylic acid ethyl esters undergo two different cleavages in basic medium, yielding the 1-aryl-2-azadiene and a thiolic species. In the presence of quinolinquinone, the isomeric 1-aryl-3-ethoxycarbonyl-pyridoisoquinolin-5,10-diones and 3-amino-3-ethoxycarbonyl-dihydrothienoquinolin- 4,9-diones are formed by a hetero-Diels–Alder reaction and 1,4-Michael addition reaction, respectively. A mechanism for the formation of the reaction products is presented

Thiazolidin-4-one formation. Mechanistic and synthetic aspects of the reaction of imines and mercaptoacetic acid under microwave and conventional heating

Microwave irradiation of a mixture of benzylidene-anilines and mercaptoacetic acid in benzene gives 1,3-thiazolidin-4- ones in very high yield (65–90%), whereas the same reaction performed through using the conventional method, at refluxtemperature, requires a much longer time and gives a much lower yield (25–69%). This difference seems to be due to someintermediates and by-products formed during the conventional reaction. On the basis of 1H NMR studies, two differentmechanisms, acting in benzene and in DMF, respectively, have been hypothesized for the thiazolidin-4-one system formation

Link Mining for Kernel-based Compound-Protein Interaction Predictions Using a Chemogenomics Approach

Virtual screening (VS) is widely used during computational drug discovery to reduce costs. Chemogenomics-based virtual screening (CGBVS) can be used to predict new compound-protein interactions (CPIs) from known CPI network data using several methods, including machine learning and data mining. Although CGBVS facilitates highly efficient and accurate CPI prediction, it has poor performance for prediction of new compounds for which CPIs are unknown. The pairwise kernel method (PKM) is a state-of-the-art CGBVS method and shows high accuracy for prediction of new compounds. In this study, on the basis of link mining, we improved the PKM by combining link indicator kernel (LIK) and chemical similarity and evaluated the accuracy of these methods. The proposed method obtained an average area under the precision-recall curve (AUPR) value of 0.562, which was higher than that achieved by the conventional Gaussian interaction profile (GIP) method (0.425), and the calculation time was only increased by a few percent

The role of endocannabinoid signaling in the molecular mechanisms of neurodegeneration in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of progressive neurodegenerative disease characterized by cognitive impairment and mental disorders. The actual cause and cascade of events in the progression of this pathology is not fully determined. AD is multifaceted in nature and is linked to different multiple mechanisms in the brain. This aspect is related to the lack of efficacious therapies that could slow down or hinder the disease onset/progression. The ideal treatment for AD should be able to modulate the disease through multiple mechanisms rather than targeting a single dysregulated pathway. Recently, the endocannabinoid system emerged as a novel potential therapeutic target to treat AD. In fact, exogenous and endogenous cannabinoids seem to be able to modulate multiple processes in AD, although the mechanisms that are involved are not fully elucidated. This review provides an update of this area. In this review, we recapitulate the role of endocannabinoid signaling in AD and the probable mechanisms through which modulators of the endocannabinoid system provide their effects, thus highlighting how this target might provide more advantages over other therapeutic targets

Draft Genome Sequences of Three Novel Staphylococcus arlettae Strains Isolated from a Disused Biological Safety Cabinet

The genome sequences of three new strains of Staphylococcus arlettae named Bari1, Bari2, and Bari3 are presented. The strains exhibited tolerance to hexavalent chromium ions. An sprC gene encoding a putative chromium transporter was present in each of the three draft genome sequences