Workload control in unbalanced job shops

Workload control (WLC) has been developed as a production planning and control approach for job shop manufacturing. By balancing loads across work centres, WLC anticipates the fact that multiple work centres may become potential bottlenecks in the short term. This approach is generally tested in job shop models that assume equal utilisation levels for all work centres, which will create maximum bottleneck shiftiness. However, job shop practice clearly shows differences in utilisation levels, which means that some work centres can be seen as non-bottlenecks, having protective capacity. This study investigates the effect of different levels of protective capacity on the performance of state-of-the-art WLC release methods. More in detail, it shows how the level of protective capacity interacts with the influence of workload norms at work centres. Despite the fact that WLC has been developed for highly balanced utilisations, results indicate that WLC could also be effective in unbalanced situations. However, norm setting requires careful attention. Disregarding the norms of non-bottleneck work centres, a common sense approach, might strongly deteriorate performance when the level of protective capacity is not sufficiently high. Contrarily, tighter norms for non-bottleneck work centres are shown to perform better in this situation.     

Microglia Response and In Vivo Therapeutic Potential of Methylprednisolone‐Loaded Dendrimer Nanoparticles in Spinal Cord Injury

The control and manipulation of cells that trigger secondary mechanisms following spinal cord injury (SCI) is one of the first opportunities to minimize its highly detrimental outcomes. Herein, the ability of surface‐engineered carboxymethylchitosan/polyamidoamine (CMCht/PAMAM) dendrimer nanoparticles to intracellularly deliver methylprednisolone (MP) to glial cells, allowing a controlled and sustained release of this corticosteroid in the injury site, is investigated. The negatively charged MP‐loaded CMCht/PAMAM dendrimer nanoparticles with sizes of 109 nm enable a MP sustained release, which is detected for a period of 14 days by HPLC. In vitro studies in glial primary cultures show that incubation with 200 μg mL^?1 nanoparticles do not affect the cells' viability or proliferation, while allowing the entire population to internalize the nanoparticles. At higher concentrations, microglial cell viability is proven to be affected in response to the MP amount released. Following lateral hemisection lesions in rats, nanoparticle uptake by the spinal tissue is observed 3 h after administration. Moreover, significant differences in the locomotor output between the controls and the MP‐loaded nanoparticle‐treated animals one month after the lesion are observed. Therefore, MP‐loaded CMCht/PAMAM dendrimer nanoparticles may prove to be useful in the reduction of the secondary injury following SCI.     

Removal of 2,4-dichlorophenol and pentachlorophenol from waters by sorption using coal fly ash from a Portuguese thermal power plant

Chlorophenols are one of the most important groups of priority pollutants, due to their high toxicity, mutagenicity and carcinogenicity. Although activated carbon has been the preferred choice for the removal of such pollutants from wastewaters, the search for cheaper alternative sorbents became common in the last years. Fly ash, a by-product from coal burning power plants, has a surface composition that may enable the sorption of specific organic compounds. Therefore, this feasibility study presents the optimization of the operating parameters of a fixed-bed column containing fly ash particles, percolated by aqueous solutions of 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP) with concentrations of 1 and 100 microg/ml. Both chlorophenols were analysed by gas chromatography with electron capture detection (GC-ECD), after solid-phase microextraction (SPME), with limits of detection (LODs) of 7.28 microg/l for 2,4-DCP and 1.76 microg/l for PCP. Removal efficiencies above 99% were obtained for an initial concentration of 10 microg/ml of chlorophenols. Column saturation was achieved after 7h of continuous operation for 2,4-DCP and 10h for the PCP for feed levels of 10 microg/ml. Fly ash exhibited more affinity towards the sorption of PCP, in comparison to 2,4-DCP.     

Biodegradable deep-eutectic mixtures as electrolytes for the electrochemical synthesis of conducting polymers

The use of inexpensive and biodegradable deep-eutectic ionic mixtures as solvents for the electrochemical synthesis of conducting polymers could potentially improve the sustainability of these processes and reduce their economic cost. Such an unexplored approach was investigated in this communication by growing a model polymer such as polyaniline from a 1:2 mixture of choline chloride and 1,2-ethanediol (the so-called Propeline) using potentiodynamic and potentiostatic electrochemical procedures. Beyond a preparation method, cyclic voltammetry was also used to characterize the growth of the polymers. The morphology of the films, and their optical properties, were assessed ex-situ by means of scanning electron microscopy and spectroscopic measurements in the UV–vis. The polyanilines thus prepared exhibited nanoparticulated morphology and high reversibility to doping/dedoping which evidences fast charge transport across the films. Excellent conductivities higher than 50?S?cm^?1 were found under this approach.     

Asymmetric Intramolecular C?H Insertion of α‐Diazoacetamides in Water by Dirhodium(II) Catalysts Derived from Natural Amino Acids

The asymmetric dirhodium(II)‐catalyzed intramolecular C H insertion of α‐diazo acetamides in water is described for the first time. The use of natural α‐amino acids as chiral ligands allowed the preparation of novel dirhodium(II) homochiral complexes by a simple procedure consisting of the in situ ligand exchange starting from dirhodium tetraacetate. The catalytic system was further reused up to 7 cycles and β‐lactams were obtained in good yields and enantiomeric excess.     

An Accessibility–Maximization Approach to Road Network Planning

Accessibility is a key factor in defining the quality of life and potential for development of both cities and regions. This article presents a new accessibility–maximization approach to inter–urban road network long–term planning. The approach is based on a nonlinear combinatorial optimization model. Two heuristics have been developed for solving the model, based on local search and simulated annealing principles, respectively. The efficiency of the heuristics was evaluated on a sample of test problems involving 10–, 20–, and 40–node networks. In the analysis both solution quality and computing effort were taken into account. The approach was used to analyze the ongoing transformation of the Portuguese main road network. The results obtained so far indicate that the model is a valuable decision–aid tool for inter–urban road network long–term planning.     

Lipid-based nanoparticles for siRNA delivery in cancer therapy: paradigms and challenges

RNA interference (RNAi) is a specific gene-silencing mechanism that can be mediated by the delivery of chemical synthesized small-interfering RNA (siRNA). RNAi might constitute a novel therapeutic approach for cancer treatment because researchers can easily design siRNA molecules to inhibit, specifically and potently, the expression of any protein involved in tumor initiation and progression. Despite all the potential of siRNA as a novel class of drugs, the limited cellular uptake, low biological stability, and unfavorable pharmacokinetics of siRNAs have limited their application in the clinic. Indeed, blood nucleases easily degrade naked siRNAs, and the kidneys rapidly eliminate these molecules. Furthermore, at the level of target cells, the negative charge and hydrophilicity of siRNAs strongly impair their cellular internalization. Therefore, the translation of siRNA to the clinical setting is highly dependent on the development of an appropriate delivery system, able to ameliorate siRNA pharmacokinetic and biodistribution properties. In this regard, major advances have been achieved with lipid-based nanocarriers sterically stabilized by poly(ethylene glycol) (PEG), such as the stabilized nucleic acid lipid particles (SNALP). However, PEG has not solved all the major problems associated with siRNA delivery. In this Account, the major problems associated with PEGylated lipid-based nanoparticles, and the different strategies to overcome them are discussed. Although PEG has revolutionized the field of nanocarriers, cumulative experience has revealed that upon repeated administration, PEGylated liposomes lose their ability to circulate over long periods in the bloodstream, a phenomenon known as accelerated blood clearance. In addition, PEGylation impairs the internalization of the siRNA into the target cell and its subsequent escape from the endocytic pathway, which reduces biological activity. An interesting approach to overcome such limitations relies on the design of novel exchangeable PEG-derivatized lipids. After systemic administration, these lipids can be released from the nanoparticle surface. Moreover, the design and synthesis of novel cationic lipids that are more fusogenic and the use of internalizing targeting ligands have contributed to the emergence of novel lipid-based nanoparticles with remarkable transfection efficiency.     

Dispersion-supported transmission at 20 Gbit/s over 53 km standardsinglemode fibre

The optical transmission of 20 Gbit/s signals over a record distance of 53 km standard nondispersion-shifted singlemode fibre (SMF) without optical dispersion compensation has been demonstrated successfully using a directly modulated MQW DFB laser operating at 1544 nm     

Implementing Thermometry on Silicon Surfaces Functionalized by Lanthanide‐Doped Self‐Assembled Polymer Monolayers

The thermal gradients generated at submicrometer scale by the millions of transistors contained in integrated circuits are becoming the key limiting factor for device integration in micro‐ and nanoelectronics. Noncontact thermometric techniques with high‐spatial resolution are, thus, essential for noninvasive off‐chip characterization and heat management on Si surfaces. Here, the first ratiometric luminescent molecular thermometer implemented in a self‐assembled polymer monolayer functionalized Si surface is reported. The functionalization of Si surfaces with luminescent thermometers constitutes a proof‐of‐concept that foretells a wide range of applications in Si‐based micro‐ and nanostructures. The thermometric functionalization of the Si surface with Tb³⁺ and Eu³⁺ complexes leads to a thermal sensitivity up to 1.43% K^?1, a cycle–recycle reliability of 98.6%, and a temperature uncertainty of less than 0.3 K. The functionalized surface presents reversible bistability that can be used as an optically active molecular demultiplexer.     

A QoS-enabled resource management scheme for F-HMIPv6 micro mobility approach

In the near future, wireless networks will certainly run real-time applications with special Quality of Service (QoS) requirements. In this context micro mobility management schemes such as Fast Handovers over Hierarchical Mobile IPv6 (F-HMIPv6) will be a useful tool in reducing Mobile IPv6 (MIPv6) handover disruption and thereby to improve delay and losses. However, F-HMIPv6 alone does not support QoS requirements for real-time applications. Therefore, in order to accomplish this goal, a novel resource management scheme for the Differentiated Services (DiffServ) QoS model is proposed to be used as an add-on to F-HMIPv6. The new resource management scheme combines the F-HMIPv6 functionalities with the DiffServ QoS model and with network congestion control and dynamic reallocation mechanisms in order to accommodate different QoS traffic requirements. This new scheme based on a Measurement-Based Admission Control (MBAC) algorithm is effective, simple, scalable and avoids the well known traditional resource reservation issues such as state maintenance, signaling overhead and processing load. By means of the admission evaluation of new flows and handover flows, it is able to provide the desired QoS requirements for new flows while preserving the QoS of existing ones. The evaluated results show that all QoS metrics analyzed were significantly improved with the new architecture indicating that it is able to provide a highly predictive QoS support to F-HMIPv6.