Enzymatic esterification of eugenol and benzoic acid by a novel chitosan-chitin nanowhiskers supported Rhizomucor miehei lipase: Process optimization and kinetic assessments

A biotechnological route via enzymatic esterification was proposed as an alternative way to synthesize the problematic anti-oxidant eugenyl benzoate. The new method overcomes the well-known drawbacks of the chemical route in favor of a more sustainable reaction process. The present work reports a Box-Behnken design (BBD) optimization process to synthesize eugenyl benzoate by esterification of eugenol and benzoic acid catalyzed by the chitosan-chitin nanowhiskers supported Rhizomucor miehei lipase (RML-CS/CNWs). Effects of four reaction parameters: reaction time, temperature, substrate molar ratio of eugenol: benzoic acid and enzyme loading were assessed. Under optimum conditions, a maximum conversion yield as high as 66% at 50 °C in 5 h using 3 mg/mL of RML-CS/CNWs, and a substrate molar ratio (eugenol: benzoic acid) of 3:1. Kinetic assessments revealed the RML-CS/CNWs catalyzed the reaction via a ping-pong bi–bi mechanism with eugenol inhibition, characterized by a Vmax of 3.83 mM min-1. The Michaelis–Menten constants for benzoic acid (Km,A) and eugenol (Km,B) were 34.04 and 138.28 mM, respectively. The inhibition constant for eugenol (Ki,B) was 438.6 mM while the turnover number (kcat) for the RML-CS/CNWs-catalyzed esterification reaction was 40.39 min-1. RML-CS/CNWs were reusable up to 8 esterification cycles and showed higher thermal stability than free RML

Innovative practice in producing competent Malaysian engineers

This study presents an innovative practice in the Malaysian engineering education system which originated from the historical development of Malaysian education. The historical development has instigated the two streams of Malaysian higher education sectors; public and private universities as well as the university programme offerings and the language of instruction. In order to extricate itself from the system introduced by the British, Malaysia has introduced an innovative element into its engineering practice. The research applies the qualitative approach whereby inductive and deductive analytical strategies were performed. The findings revealed that the Malaysian education system has advanced into an independent own mould engineering education system which is very much shaped by Islamic values and beliefs and, the Malaysian culture - with the aim of producing innovative and competent engineers to compete in this globalized world

Assessment on recent landslide susceptibility mapping methods: A review

Landslide is a destructive natural hazard that causes severe property loss and loss of lives. Numerous researchers have developed landslide susceptibility maps in order to forecast its occurrence, particularly in hill-site development. Various quantitative approaches are used in landslide susceptibility map production, which can be classified into three categories; statistical data mining, machine learning and deterministic approach. In this paper, we choose two regular models in each category, which are Weight of Evidence (WoE) and Frequency Ratio (FR), Artificial Neutral Networks (ANN) and Support Vector Machines (SVM), Shallow Landsliding Stability Model (SHALSTAB) and YonSei-Slope (YS-Slope). Discussion and assessment on these models are based on relevant literature

Cost optimisation of a flexible heat exchanger network with fluctuation probability using break-even analysis

Heat exchanger network (HEN) which is designed to achieve the maximum energy recovery (MER) involves the integration and interactions of multiple process streams. Small disturbances on one stream can affect other connecting streams. In order to manage these disturbances, the process to process and utility heat exchangers with bypass streams installation are typically overdesigned. However, overdesign also means higher capital investment. This study presents the cost optimisation of flexible MER HEN design which considers the fluctuation probability using break-even analysis. Data were extracted for the Pinch study and assessment for flexibility and MER was performed. The MER heat exchanger maximum size (MER-HEM) is able to handle the most critical supply temperature fluctuations while minimising the utility consumption. The overdesign factor can affect the total annualised cost at a certain probability of fluctuation occurrence. Thus, the break-even analysis of the MER-HEM is performed to determine the probability that resulted in high savings of total annualised cost. Two Scenarios (A and B) with different fluctuation probabilities were used to demonstrate the methodology. Application of the proposed methodology on an Illustrative Case Study shows that, for the fluctuation at hot stream H1, the MER-HEM gives the optimum annualised total cost for Scenario A with additional savings of 10 %. For Scenario B, the MER heat exchanger original size (MER-HEO) is the optimum, giving an additional savings of 4 %. For cold stream C1, the MER-HEO is the optimum for Scenario A, giving an extra savings of 4 % whereas the MER-HEM is the optimum for Scenario B, yielding an extra savings of 9 %

Effect of blowing agent concentration on cell morphology and impact properties of natural rubber foam

The concentration of sodium bicarbonate as a chemical blowing agent was varied to evaluate its effect on the morphology and impact properties of natural rubber foam. The expandable rubber samples were prepared using a conventional two-roll mill and were then expanded via a heat transfer foaming process using compression moulding and an air-circulating oven. The physical properties of the natural rubber foams were characterised, and the results were observed to systematically correlate with the impact properties of the foam. The absorbed energy of the foam increases with decreasing crosslink density and relative foam density, which is associated with the formation of smaller foam cells and an increase in the number of cells per unit volume

Prediction of Protein Binding Regions in Disordered Proteins

Many disordered proteins function via binding to a structured partner and undergo a disorder-to-order transition. The coupled folding and binding can confer several functional advantages such as the precise control of binding specificity without increased affinity. Additionally, the inherent flexibility allows the binding site to adopt various conformations and to bind to multiple partners. These features explain the prevalence of such binding elements in signaling and regulatory processes. In this work, we report ANCHOR, a method for the prediction of disordered binding regions. ANCHOR relies on the pairwise energy estimation approach that is the basis of IUPred, a previous general disorder prediction method. In order to predict disordered binding regions, we seek to identify segments that are in disordered regions, cannot form enough favorable intrachain interactions to fold on their own, and are likely to gain stabilizing energy by interacting with a globular protein partner. The performance of ANCHOR was found to be largely independent from the amino acid composition and adopted secondary structure. Longer binding sites generally were predicted to be segmented, in agreement with available experimentally characterized examples. Scanning several hundred proteomes showed that the occurrence of disordered binding sites increased with the complexity of the organisms even compared to disordered regions in general. Furthermore, the length distribution of binding sites was different from disordered protein regions in general and was dominated by shorter segments. These results underline the importance of disordered proteins and protein segments in establishing new binding regions. Due to their specific biophysical properties, disordered binding sites generally carry a robust sequence signal, and this signal is efficiently captured by our method. Through its generality, ANCHOR opens new ways to study the essential functional sites of disordered proteins

Cytoskeletal control of B cell responses to antigens.

The actin cytoskeleton is essential for cell mechanics and has increasingly been implicated in the regulation of cell signalling. In B cells, the actin cytoskeleton is extensively coupled to B cell receptor (BCR) signalling pathways, and defects of the actin cytoskeleton can either promote or suppress B cell activation. Recent insights from studies using single-cell imaging and biophysical techniques suggest that actin orchestrates BCR signalling at the plasma membrane through effects on protein diffusion and that it regulates antigen discrimination through the biomechanics of immune synapses. These mechanical functions also have a role in the adaptation of B cell subsets to specialized tasks during antibody responses