Solvent‐free acetylation of lignocellulosic fibers at room temperature: Effect on fiber structure and surface properties

Acetylation is one of the most interesting chemical treatments to improve the affinity of lignocellulosic fibers with polymeric matrices for the elaboration of several types of composites. In this paper, the acetylation of flax and wood pulp (bleached softwood Kraft pulp and thermomechanical pulp) fibers was carried out at room temperature in a solvent‐free system with acetic anhydride in the presence of sulfuric acid as catalyst. The effect of acetylation on the fine structure of fibers was investigated by spectroscopic methods, while the extent of acetylation was quantified by weight percent gain. The effect of reaction time on fiber morphology was studied at macro‐ and microscale using scanning electron microscopy, optical microscopy, and fiber quality analysis. The evolution of the hydrophobic/hydrophilic character of fibers was determined by contact angle measurements. The wettability of fibers by liquid epoxy resin was also evaluated to confirm the improvement of the affinity of acetylated fibers with the epoxy matrix. It was found that the hydrophilic character of fibers decrease with increasing reaction time, whereas the trend was less pronounced beyond specific reaction times. Acetylated fibers can therefore be potential candidates for replacing nonbiodegradable reinforcing materials in composite applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42247.     

Removal of Rhodamine B from water by cedar cone: Effect of calcinations and chemical activation

The aim of this work is to obtain optimal preparation conditions of cedar cone (CC) using calcinations and the chemical activation. For the calcinations treatment, the temperature was varied from 300 to 600 °C at different calcinations durations (30 min–5.00 h 30 min), while the chemical activation was carried on using bases and acids reagents such as: H₃PO₄, H₂SO₄, HNO₃ for the acid reagents and NaOH, Na₂SO₄, Na₂CO₃ for bases ones successively, at the same concentration of 0.1 mol/L. Furthermore other chemical activation parameters were tested such as acids concentration and impregnation ratio. The efficiency of the treated cedar cone was tested by basic dye Rhodamine B (RhB) sorption from aqueous solutions in a batch system. The results show that the maximum dye removal was obtained for the case of calcined cedar cone at a temperature of 500 °C with a 4 h30 min time duration and for the case of HNO₃ activated cedar cone at a concentration of 2 mol/L with an impregnation ratio of 20.     

Design and Implementation of a Dynamic Evolution Controller for Single-phase Inverters with Large Load Changes

Abstract—A new controller is developed for a single-phase inverter based on the dynamic evolution control method. The non-linear model equations and algorithm of the approach is derived and presented. The simulation is conducted based on the proposed method by MATLAB/Simulink to test the performance of the controller for large load variations. The system was also tested experimentally to show the feasibility of the proposed method applied to a single-phase inverter. Results show that the proposed approach is suitable for applications with large load variations. Practical results show that the controller can successfully handle a 40 times load change in less than 2 ms. It also has good output in the harmonic spectrum compared with the IEEE 519 harmonic standard during no-load and full-load conditions.     

Ionic liquids based on 1-aza-bicyclo[2,2,2]octane (Quinuclidine) salts: synthesis and physicochemical properties

A series of new hydrophobic ionic liquids based on 1-alkyl-quinuclidinium cations, quoted as C _n Quin⁺ where n is the number of carbon atoms in the alkyl chain, and on the fluorinated anion bis(trifluoromethanesulfonyl)imide (TFSI⁻) were synthesized, characterized by NMR (¹H, ¹³C), and their elemental analysis determined. Among the five compounds synthesized, only one: C₆Quin(TFSI) is liquid at ambient temperature and the others with the exception of C₁Quin(TFSI), exhibit melting points below 100 °C and can be considered as ionic liquids. With the aim of using them as electrolytes in electrochemical devices, some of their physicochemical properties such as density, dynamic viscosity and conductivity were explored. The behaviour of C₆Quin(TFSI) at a graphite electrode was investigated in the presence of added LiTFSI, by means of cyclic voltammetry for possible use as electrolyte in Li-ion batteries. Results show that the large quinuclidinium cations intercalate in the graphite layers and do not permit the reversible insertion of lithium ions.     

Red–Green–Blue (RGB) colour system approach to study the segregation and percolation in a mixture of white wheat flour and bleached wheat bran

In this work, we applied a nonintrusive measurement method based on the Red–Green–Blue (RGB) image analysis system to study the segregation and percolation in a mixture of white wheat flour and bleached wheat bran. This method intended to quantify the presence of one or several colours in the surface of mixed ingredients. The mixing of flour particles with bleached and unbleached wheat bran was studied using a 90 mm closed rotating cube. This system forced the particles to roll relative to each other so as to favourite the segregation by percolation in order to hide one colour by another. The obtained results showed a possibility of obtaining homogeneous colour when the wheat flour was mixed with the bleached wheat bran at a volume ratio of 20/5%–10%. By increasing to ratio up to 20/15% (flour/bran), the RGB system showed a presence of two colours in the surface of the mixture. Moreover, the RGB method confirmed the presence of two heterogeneous colours when the wheat flour was mixed with the unbleached wheat bran whatever the ratio (20/5%, 10% and 15%).     

Quasi-periodic self-stabilization of adaptive ARMA predictors

The stability of adaptive ARMA predictors, which present random time-varying poles, is investigated. The updating algorithm is a suboptimal version of the stochastic gradient. For narrow-band inputs local and quasi-periodic instabilities occur. At those times the output error increases exponentially but has essentially the frequency of the unstable pole of the MA predictor part. This unstable error generates in the algorithm a stabilizing drift for the (unstable) MA parameters. This behaviour, called self-stabilization (SS), is attenuated by inclusion of a (leakage) σ-factor in the updating algorithm. The SS analysis is applied to the important application of the ADPCM encoding of speech signals. It is shown that in successive encoder/decoder connections the SS phenomenon results in the accumulation of quantization distortions at each transcoder. For a digital transmission chain this is a serious drawback.     

Microneedle-Based Local Delivery of CCL22 and IL-2 Enriches Treg Homing to the Skin Allograft and Enables Temporal Monitoring of Immunotherapy Efficacy

Skin allografts only serve as temporary dressing for patients suffering major burns due to their high immunogenicity and rejection by the immune system, requiring systemic immunosuppressive therapies that lead to deleterious side effects. Microneedle arrays composed of hyaluronic acid (HA) and placed on skin allografts can locally deliver immunomodulators and simultaneously sample immune cells in interstitial fluid to monitor the response to the therapy. The cells can be retrieved from the microneedles for downstream analysis by degrading the HA using a reducing agent. Using an allogeneic skin transplantation model, it is shown that the microneedle-mediated local delivery of the chemokine CCL22 (to attract T_regs) and the cytokine IL-2 (to promote their expansion) increases the local immune suppression in the allograft. Moreover, immune cell population in the allograft correlates with that seen in the microneedles. The delivery and sampling functions of the microneedle arrays can help regulate the immune system locally, without inducing systemic immune suppression, and facilitate the monitoring of the response to the therapy following skin transplantation.     

New local diversification techniques for flexible job shop scheduling problem with a multi-agent approach

The Flexible Job Shop problem is among the hardest scheduling problems. It is a generalization of the classical Job Shop problem in that each operation can be processed by a set of resources and has a processing time depending on the resource used. The objective is to assign and to sequence the operations on the resources so that they are processed in the smallest time. In our previous work, we have proposed two Multi-Agent approaches based on the Tabu Search (TS) meta-heuristic. Depending on the location of the optimisation core in the system, we have distinguished between the global optimisation approach where the TS has a global view on the system and the local optimisation approach (FJS MATSLO) where the optimisation is distributed among a collection of agents, each of them has its own local view. In this paper, firstly, we propose new diversification techniques for the second approach in order to get better results and secondly, we propose a new promising approach combining the two latter ones. Experimental results are also presented in this paper in order to evaluate these new techniques.     

Human Macrophage Galactose-Type Lectin (MGL) Recognizes the Outer Core of Escherichia coli Lipooligosaccharide

Carbohydrate–lectin interactions intervene in and mediate most biological processes, including a crucial modulation of immune responses to pathogens. Despite growing interest in investigating the association between host receptor lectins and exogenous glycan ligands, the molecular mechanisms underlying bacterial recognition by human lectins are still not fully understood. Herein, a novel molecular interaction between the human macrophage galactose-type lectin (MGL) and the lipooligosaccharide (LOS) of Escherichia coli strain R1 is described. Saturation transfer difference NMR spectroscopy analysis, supported by computational studies, demonstrated that MGL bound to the purified deacylated LOS_R1 mainly through recognition of its outer core and established crucial interactions with the terminal Galα(1,2)Gal epitope. These results assess the ability of MGL to recognise glycan moieties exposed on Gram-negative bacterial surfaces.     

Performance analysis of hybrid photovoltaic/diesel energy system under Malaysian conditions

Standalone diesel generating system utilized in remote areas has long been practiced in Malaysia. Due to highly fluctuating diesel price, such a system is seemed to be uneconomical, especially in the long run if the supply of electricity for rural areas solely depends on such diesel generating system. This paper would analyze the potential use of hybrid photovoltaic (PV)/diesel energy system in remote locations. National Renewable Energy Laboratory’s (NREL) HOMER software was used to perform the techno-economic feasibility of hybrid PV/diesel energy system. The investigation demonstrated the impact of PV penetration and battery storage on energy production, cost of energy and number of operational hours of diesel generators for the given hybrid configurations. Emphasis has also been placed on percentage fuel savings and reduction in carbon emissions of different hybrid systems. At the end of this paper, suitability of utilizing hybrid PV/diesel energy system over standalone diesel system would be discussed mainly based on different solar irradiances and diesel prices.