Kinetic Analysis Misinterpretations Due to the Occurrence of Enzyme Inhibition by Reaction Product: Comparison between Initial Velocities and Reaction Time Course Methodologies

The Michaelis–Menten equation (MME) has been extensively used in biochemical reactions, but it is not appropriate when the reaction product inhibits the enzyme. Under these circumstances, each determined initial velocity, v0, is one experimental point that actually belongs to a different MME because enzymatic product inhibition occurs as the reaction starts. Furthermore, the inhibition effect is not constant, since the concentration of the product inhibitor rises as time increases. To unveil the hidden enzyme inhibition and to simultaneously demonstrate the superiority of an integrated Michaelis–Menten equation (IMME), the same range of data points, assuming product inhibition and the presence of a second different inhibitor, was used for kinetic analysis with both methodologies. This study highlights the superiority of the IMME methodology for when the enzyme is inhibited by the reaction product, giving a more coherent inhibition model and more accurate kinetic constants than the classical MME methodology.

Methodical Aspects of MCDM Based E-Commerce Recommender System

The aim of this paper is to present the use of an innovative approach based on MCDM methods as the main component of a consumer Decision Support System (DSS) by recommending the most suitable products among a given set of alternatives. This system provides a reliable recommendation to the consumer in the form of a compromise ranking constructed from the five MCDM methods: the hybrid approach TOPSIS-COMET, COCOSO, EDAS, MAIRCA, and MABAC. Each of the methods used contributes significantly to the final compromise ranking built with the Copeland strategy. Chosen MCDM methods were combined with the objective CRITIC weighting method, and their performance was presented on the illustrative example of choosing the most suitable mobile phone. A sensitivity analysis involving the rw and WS correlation coefficients was performed to determine the match between the compromise ranking of the candidates and the rankings provided by each MCDM method. Sensitivity analysis demonstrated that all investigated compromise candidate rankings show high convergence with the rankings provided by the particular MCDM methods. Thus, the performed study proved that the proposed approach shows high potential to be successfully used as a central component of DSS for recommending the most suitable product. Such DSS could be a universal and future-proof solution for e-commerce sites and websites, providing advanced product comparison capabilities in delivering a recommendation to the user as a final ranking of alternatives.

Product Comparison between Local Product and Technology Aided Mambong Pottery

There are various traditional Malay potteries such as Labu Sayong, Buyung and Terenang. Kelantan traditional pottery known as Mambong. The objectives of this research are to compare and characterize the density, strength, physical appearance and shrinkage of traditional and slip casted Mambong pottery. Traditional Mambong pottery has been brought from the potter at Mambnog village and slip casted Mambong pottery is made by using slip casting method. Density of sample is measured by using Archimedes principal. Traditional Mambong pottery show the higher value of density compared to slip casting Mambong pottery. The average value of density for traditional Mambong pottery was 1.763 g/cm3, while the average value of density for Mambong pottery that was fabricated via slip casting was 1.461 g/cm3. Due to the presence of iron in clay, the colour of Mambong pottery changes from brown to reddish-brown after firing process. Traditional Mambong pottery shows the higher percentage of dry shrinkage which was 9.76 % compared to slip casting Mambong pottery which was 5.72 %. Traditional Mambong pottery also shows the higher percentage of fired shrinkage which was 1 % compared to slip casting Mambong pottery which was 0.58 %. In conclusion, by using slip casting technique, density, physical appearance and shrinkage of pottery can be improved.

DEFECT PRODUCT COMPARISON OF THE USE OF ALCOHOL-BASED FOUNTAIN SOLUTION AND ALCOHOL-FREE IN OFFSET PRINTING

One of the main components of the fountain solution used for the offset printing technique is isoprophil alcohol (IPA), which is related to its function as a surface tension reducing agent, cooling agent for printing plates and at the same time having anti-bioorganic function. However, complaints have also been made about the weaknesses in the use of IPA related to odor, toxicity and too high evaporation rate during its use. Therefore, in this article, IPA is compared to the "alcohol-free" type when used in the field as a wetting solution mixture using a KBK offset printing machine to produce magazines using of AP 115 paper. The difference in the use of the two surfaces the tension reducing agents are identified by the waste parameters that are used, generated during consistent printing under controlled process conditions. The results obtained indicate that the use of IPA is always higher, but the use of `` non alcoholic '' tends to be more stable in controling the process.Keywords—Isoprophil Alcohol (IPA), alcohol-free fontain solution, offset printing

Improved Annotation of Untargeted Metabolomics Data Through Buffer Modifications That Shift Adduct Mass and Intensity

<p>Annotation of untargeted high-resolution full-scan LC-MS metabolomics data remains a difficult task. Existing literature suggests that LC-MS peaks can be divided into multiple major categories including “Background”, “Isotope”, “Adduct”, “Fragment” and “Candidate metabolite”. Among these, adduct annotation is a particular challenge, as the same mass difference between peaks can arise from adduct formation, fragmentation, or different biological species. To address this, here we describe a Buffer Modification Workflow (BMW), in which the same sample is run by LC-MS in both liquid chromatography solvent with ¹⁴NH₃-acetate buffer, and in solvent with the buffer modified with ¹⁵NH₃-formate. Buffer switching results in characteristic mass and signal intensity changes for adduct peaks, facilitating their annotation. In analyzing the candidate metabolite peaks, we recognized that some paradoxically increased in intensity over time between sample preparation and analysis. We show that such peaks are formed by chemical reactions between known metabolites and the extraction buffer and accordingly categorize these peaks as “Reaction Product”. Comparison using yeast extracts of BMW with a stable isotope labeling-based workflow suggests that BMW captures > 90% of candidate metabolites. This new workflow is well-suited to biological samples that cannot be readily isotope labeled, such as mammalian tissues and tumors. Application to mouse liver identified 26% of ~ 27,000 total peaks across positive and negative mode as candidate metabolites, of which ~ 2600 showed HMDB or KEGG database formula match.</p>