A Taguchi design approach for the enhancement of a detergent-biocompatible alkaline thermostable protease production by Streptomyces mutabilis strain TN-X30

The ability of microorganisms to grow at high temperature, alkaline pH, and high salinity makes them an attractive target for enzyme-production with several industrial applications. One strain TN-X30 has been selected as protease producer and identified as Streptomyces mutabilis after a phenotypic and molecular study. Its production of protease was improved using Taguchi L27 design. The strategy was carried out to identify the optimum levels and the interaction of the screened factors. Following this step, maximum protease activity (10,895 U/ml) was achieved after 6-days of incubation. The TN-X30 protease activity had an optimum of pH and temperature of 10 and 65°C, respectively. Thermodynamic parameters at 60°C were enthalpy 14.26 kJ/mol, entropy −220 J/mol/K, and Gibbs free energy 90.53 kJ/mol. TN-X30 protease production displayed a 16-fold increase reaching 175,000 U/ml in a 100-L fermentor. Furthermore, the lyophilization in presence of sorbitol enhanced the stability of the TN-X30 protease which remained active at 75% after 24-months of storage. The lyophilized TN-X30 protease exhibited exceptional stability indexes in presence of some known commercialized detergent components as NEODOL® 25-7, Dehydol® LT 7, Na₂ CMC, Galaxy LAS, Galaxy LES 70, Galaxy 110, Galaxy CAPB Plus, and Sulfacid K. The lyophilized enzyme also displayed high stability with respect to both solid and liquid detergents. Finally, TN-X30 protease exhibited remarkable destaining of blood, egg, and chocolate stained cloth pieces. These findings may promote TN-X30 protease for use as bioadditive in detergent formulation, thereby reducing environmental chemical threat.     

Theoretical Study of the Doping Effects of n-type and p-type Silicon on the Surface Plasmon Resonance Using a 2D Grating

Silicon - A theoretical study on the excitation of surface plasmon (SP) through a 2D doping silicon gratingis present. Both n- and p-type doping silicon were used. The doping effects of n -type and...     

Influence of Fe/Zn content on the structural,and optical properties of nontoxic and earth-abundant Cu2ZnxFe1 − xSnS4 (x = 0, 0.25, 0.5, 0.75 and 1) compounds

Journal of Materials Science: Materials in Electronics - In this paper, we report the synthesis of multicomponent Cu2ZnxFe1???xSnS4 (CZFTS)...     

Technological learning in energy–environment–economy modelling: A survey

This paper aims at providing an overview and a critical analysis of the technological learning concept and its incorporation in energy–environment–economy models. A special emphasis is put on surveying and discussing, through the so-called learning curve, both studies estimating learning rates in the energy field and studies incorporating endogenous technological learning in bottom-up and top-down models. The survey of learning rate estimations gives special attention to interpreting and explaining the sources of variability of estimated rates, which is shown to be mainly inherent in R&D expenditures, the problem of omitted variable bias, the endogeneity relationship and the role of spillovers. Large-scale models survey show that, despite some methodological and computational complexity related to the non-linearity and the non-convexity associated with the learning curve incorporation, results of the numerous modelling experiments give several new insights with regard to the analysis of the prospects of specific technological options and their cost decrease potential (bottom-up models), and with regard to the analysis of strategic considerations, especially inherent in the innovation and energy diffusion process, in particular the energy sector's endogenous responses to environment policy instruments (top-down models).     

Effects of excimer laser annealing energy on the properties of thermally evaporated tin antimony sulfide thin films and TEM characterization of the powder

Tin antimony sulfide (TAS) is one of the most promising compounds for the next generation of optoelectronic and thin film photovoltaic devices. TAS material was synthesized by a solid-state reaction using earth-abundant tin, antimony and sulfur elements. The structural properties of the TAS powder were investigated by transmission electron microscopy (TEM). X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and selected electron diffraction (SAED) were employed to establish the crystalline nature of the powder. The TEM observations demonstrated that the powder was polycrystalline in nature with rod-shaped structure. The effects of excimer laser annealing (ELA) at different pulse energies on the structural, morphological and optical properties of thermally evaporated TAS films were investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy measurements showed that the films annealed by an excimer laser of 248 nm were amorphous for weak energy densities whereas the sample irradiated with 111 mJ/cm^??2 was polycrystalline with a preferential \({\text{(}}\overline {{\text{2}}} {\text{1}}\overline {{\text{3}}} {\text{)}}\) orientation. The ELA effects on the optical properties were also studied in the wavelength range 300–1800 nm by using UV–Vis–NIR spectroscopy. The absorption coefficient of all samples in the fundamental absorption region is higher than 10⁴ cm^?1. We also found that the optical band gap decreases from 2.04 to 1.84 eV after irradiating the thin films under different laser energy densities.     

Design of concurrent error detectable current-mode A/D converters for real-time applications

Analog MOS circuits are becoming increasingly sophisticated in terms of checking and correcting themselves. Self-correcting, self-compensating, or self-calibrating techniques eliminate errors traditionally associated with analog circuits. For real-time applications, however, it is rather difficult to achieve validation of the data generated from analog-to-digital (A/D) converters in the presence of faulty switching element(s). Conventionally, the validation is accomplished by using a high resolution and high accuracy D/A converter and a window comparator; i.e., the validation must highly depend on the reliability of both the D/A converter and the window comparator. In this paper, a novel current-mode A/D converter design with concurrent error detection (CED) capability is presented. The A/D converter does not need well-matched components and high-gain amplifiers. Results show that the proposed design can detect all the transient faults and most of the permanent faults. The proposed design allows users to easily switch to the normal operation mode where CED capability is not used, without causing any performance degradation.     

A tabu search heuristic for bandwidth allocation in fixed WiMAX

In this paper, we propose a mathematical model with the aim to give guidelines for the dimensioning of fixed WiMAX bandwidth provisioning service to residential customers. Our proposal relies on the modeling of a CAC policy associated to a priority-based bandwidth sharing strategy. Both mechanisms aim to satisfy Quality of Service constraints while maximizing the gain of the system. But unlike in Khemiri et al. (Optimal call admission control for an IEEE 802.16 wireless metropolitan area network. In: International Conference on Network Control and Optimization, 2007, accepted), we do not necessarily seek here for an optimal CAC policy. We rather consider a coordinate convex CAC policy, whose mathematical modeling leads to a tractable analytical resolution. We chose the Guaranteed Minima (GM) policy, which consists in reserving a specified amount of bandwidth for each traffic class. The remaining bandwidth is shared between all traffic classes. The purpose of the paper is to determine, using an analytical model and a heuristic approach, the nearly-optimal sizes of the GM reservation thresholds associated to each type of connection. The main concern here is to propose simple and robust computational methods, which can be easily and efficiently used to dimension a realistic WiMAX network.     

Highly sensitive label-free immunosensor for ochratoxin A based on functionalized magnetic nanoparticles and EIS/SPR detection

A label-free immunosensor for the detection of ochratoxin A (OTA) based on use of magnetic nanoparticles (MNPs) was developed. A gold electrode was modified using bovine serum albumin conjugate with a glutaraldehyde-thiolamine linker, creating a layer that prevents non-specific binding of OTA on gold. The OTA antibodies were attached to MNPs using the carbodiimide chemistry and afterwards were immobilized on the modified gold electrode using a strong magnetic field. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and surface plasmon resonance (SPR) were used to characterize each step in immunosensor development. The impedance variation due to the specific antibody-OTA interaction was correlated with the OTA concentration in the samples. The increase in electron-transfer resistance values was proportional to the concentration of OTA on a linear range between 0.01 and 5 ng/mL, with a detection limit of 0.01 ng/mL. SPR measurements showed a larger response range (1-50 ng/mL) with a detection limit of 0.94 ng/mL. Analytical results were in accordance with standard ELISA test kit.     

A fuzzy multi-criteria decision-making approach for managing performance and risk in integrated procurement–production planning

Nowadays in Supply Chain (SC) networks, a high level of risk comes from SC partners. An effective risk management process becomes as a consequence mandatory, especially at the tactical planning level. The aim of this article is to present a risk-oriented integrated procurement–production approach for tactical planning in a multi-echelon SC network involving multiple suppliers, multiple parallel manufacturing plants, multiple subcontractors and several customers. An originality of the work is to combine an analytical model allowing to build feasible scenarios and a multi-criteria approach for assessing these scenarios. The literature has mainly addressed the problem through cost or profit-based optimisation and seldom considers more qualitative yet important criteria linked to risk, like trust in the supplier, flexibility or resilience. Unlike the traditional approaches, we present a method evaluating each possible supply scenario through performance-based and risk-based decision criteria, involving both qualitative and quantitative factors, in order to clearly separate the performance of a scenario and the risk taken if it is adopted. Since the decision-maker often cannot provide crisp values for some critical data, fuzzy sets theory is suggested in order to model vague information based on subjective expertise. Fuzzy Technique for Order of Preference by Similarity to Ideal Solution is used to determine both the performance and risk measures correlated to each possible tactical plan. The applicability and tractability of the proposed approach is shown on an illustrative example and a sensitivity analysis is performed to investigate the influence of criteria weights on the selection of the procurement–production plan.     

Development of energy efficiency improvement in the Tunisian hotel sector: a case study

Tunisia expects a very large growth in energy demand but Tunisian' indigenous energy resources are limited. Today Tunisian' energy resources meet the total primary energy demand. In short time Tunisia will become an importer country for primary energy.Energy consumption and conservation in Tunisia has received growing attention in recent years. This paper presents the results and analysis from the data collected during the energy audits of a hotel unit located in the center of Tunis during the years 1987, 1996 and 2002. Two energy conservation measures were carried out to investigate the energy savings after two energy audits. The objective was to obtain a quantified energy saved from the effects of efficient technologies.Based on the findings presented in this paper it is suggested there exists significant energy savings potentials for the Tunisian hotel industry.