Optimization of Freeze Drying Conditions for Purified Pectinase from Mango (Mangifera indica cv. Chokanan) Peel

Response surface methodology (RSM) along with central composite design (CCD) was applied to optimize the freeze drying conditions for purified pectinase from mango (Mangifera indica cv. Chokanan) peel. The effect of pectinase content (-2.66, 62.66 mg/mL), Arabic gum (-1.21, 10.21%, w/v), and maltodextrin (0.73, 7.26%, w/v) as independent variables on activity, yield, and storage stability of freeze-dried enzyme was evaluated. Storage stability of pectinase was investigated after one week at 4 °C and yield percentage of the enzyme after encapsulation was also determined. The independent variables had the most significant (p < 0.05) effect on pectinase activity and yield of the enzyme. It was observed that the interaction effect of Arabic gum and maltodextrin improved the enzymatic properties of freeze-dried pectinase. The optimal conditions for freeze-dried pectinase from mango peel were obtained using 30 mg/mL of pectinase content, 4.5 (%, w/v) of Arabic gum, and 4 (%, w/v) of maltodextrin. Under these conditions, the maximum activity (11.12 U/mL), yield (86.4%) and storage stability (84.2%) of encapsulated pectinase were achieved.     

Towards automated HPC scheduler configuration tuning

High performance computing (HPC) systems allow researchers and businesses to harness large amounts of computing power needed for solving complex problems. In such systems a job scheduler prioritizes the execution of jobs belonging to users of the system in a manner that allows the system to satisfy performance objectives for various groups of users while simultaneously making efficient use of available resources. Typically, system administrators have the responsibility of manually configuring or tuning the job scheduler such that the performance objectives of user groups as well as system‐level performance objectives are met. Modern job schedulers used in production systems are quite complex. Through detailed trace‐driven simulations, we show that manually tuning the configuration of production schedulers in an environment characterized by multiple performance objectives is very challenging and may not be feasible. To alleviate this problem, this paper describes a toolset that can help a system administrator to automatically configure a scheduler such that the performance objectives for various classes of users in the system as well as other system‐level performance objectives can be satisfied. A unique aspect of this work that differentiates it from the existing work on scheduler tuning is that it has been implemented to work with a widely used production scheduler. Furthermore, in contrast to the existing work it considers the challenging real‐world problem of delivering different levels of performance to different classes of users. System administrators can exploit the toolset to react quickly to changes in performance objectives and workload conditions. Case studies using synthetic and real HPC workloads demonstrate the effectiveness of the technique. Copyright © 2011 John Wiley & Sons, Ltd.     

The morphological impact of siliceous porous carriers on copper-catalysts for selective direct CO2 hydrogenation to methanol

A series of copper-catalysts, Cu-ZnO-MnO (CZM), supported on morphologically distinct siliceous porous carriers (SBA-15, MCF, KIT-6) were synthesized and applied in direct CO₂ hydrogenation to methanol. The morphological impact of porous carriers on the formation and growth of copper crystallites and the molecular pore diffusion of the porous catalysts were investigated. Among the synthesized catalysts, KIT-6 supported catalyst (CZM/KIT-6) presented the most superior properties. The morphology of KIT-6 deterred mesopore plugging and favored the formation of small copper crystallites. CZM/KIT-6 also possessed greater resistance to copper crystallite growth and loss of copper surface area during reaction due to the pore-confining effect of the porous carrier and the larger inter-crystallites spacing among copper crystallites. The high effective diffusivity (catalyst pore-geometry dependent coefficient) of CO₂ molecules in CZM/KIT-6 could indicate efficient transfer of reactant molecules to active sites and the removal of reaction products. The superior characteristics of CZM/KIT-6 contributed to the high CO₂ conversion (8.2%) and high methanol production rate (105.3 mol/kg_cat.h) at low reaction temperature (180 °C). The methanol selectivity attained was ≥99% in all the experiments.     

Purification of serine protease from mango (Mangifera Indica Cv. Chokanan) peel using an alcohol/salt aqueous two phase system

An alcohol/salt-based aqueous two-phase (ATPS) system, as a novel method of purification, was employed to purify serine proteases from mango (Mangifera Indica Cv. Chokanan) peel. The effectiveness of different parameters, such as type and concentration of alcohol (1-propanol, 2-propanol, and ethanol), type of salt (sodium citrate, potassium phosphate, and ammonium sulphate), pH, and NaCl, on the purification and selective separation of serine protease was investigated. Desirable conditions of partition coefficient (K), selectivity (S), purification factor (P), and yield (Y%) of serine protease, using ATPS, were determined. The highest partition coefficient (64.5) and selectivity (343.2) for serine protease purification value were achieved in an ATPS of 16% (w/w) 2-propanaol, 19% (w/w) potassium phosphate, and 5% (w/v) NaCl at pH 7.5. It was demonstrated that serine protease could be recovered with a yield of 96.7% and a purification factor of 11.6.     

A distributed spectrum handoff MSRV protocol for the cognitive radio ad hoc networks

Wireless Networks - Cognitive radio technology provides opportunistic wireless spectrums access for the secondary users (SUs) while primary users (PUs) are dormant. By emergence of a PU in the...     

Assessing the bioavailability of PAHs in field-contaminated sediment using XAD-2 assisted desorption

An XAD-2 assisted desorption assay was evaluated to assess its functionality in determining the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in an aged field-contaminated sediment. In the study, various dosages of XAD-2 resin were added to abiotic sediment-water slurry systems to adsorb the PAHs from the aqueous phase thus accelerating the desorbability of these contaminants from the sediment. A parallel experiment on the biodegradation of these PAHs by microorganisms indigenous to the sediment was also conducted. Both the desorbability of the PAHs in the XAD-2 assisted desorption assay and their biodegradability decreased with time and eventually approached constant values. The two procedures showed very similar residual concentrations of PAHs for compounds with less than five benzene rings. This suggests that the XAD-2 assisted desorption assay shows promise in measuring the bioavailability of PAHs in field-contaminated sediments and could be used for predicting the end point of PAH bioremediation.     

Wavelet-based robust filtering of process data

A robust filtering methodology is proposed that reliably preserves the information encapsulated in a process signal corrupted with noise and outliers. The method is proven to be effective on benchmark examples and implemented successfully in real-time on a pilot-scale distillation column.     

Purification and characterisation of thermo-alkaline pectinase enzyme from Hylocereus polyrhizus

The thermo-alkaline pectinase enzyme from Hylocereus polyrhizus was purified 232.3-fold with a 73.3 % recovery through ammonium sulphate precipitation, gel filtration, and ion exchange chromatography. Ion exchange chromatography combined with sodium dodecyl sulphate gel electrophoresis (SDS-PAGE) revealed that the enzyme was monomeric with a molecular weight of 34.2 kDa. The pectinase exhibited broad specificity towards polygalacturonic acid, arabinan, oat spelt xylan, and pNP-α-glucopyranoside. The optimum pH and temperature were 8.0 and 75 °C, respectively. This enzyme was stable over a wide pH range (3.0–11.0) and at relatively high temperature (85 °C for 1 h). The K_m and V_max values of pectinase towards polygalacturonic acid were 2.7 mg/ml and 34.30 U/mg proteins, respectively. In addition, the enzyme activity was inhibited by Ni²⁺, Al³⁺, and Fe²⁺ and was increased in the presence of Ca²⁺ and Mg²⁺ by 120 and 112 %, respectively. The purified pectinase demonstrated robust stability in response to surfactants and oxidising agents. EDTA, which is a powerful chelating agent, did not exert any significant effect on the enzyme stability. Thus, enzymes with these unique properties may be widely used in different types of industries and biotechnological applications.     

A novel proposal for all-optical 1-bit comparator using nonlinear PhCRRs

Photonic Network Communications - All-optical comparators play crucial roles in all-optical data processing systems. In this paper, we proposed a novel structure for realizing an all-optical...