Carboxymethylcellulose/polyaniline blends. Synthesis and properties

Summary Polyaniline (PANI) as one of the conducting polymers focuses intensive research on both scientific and practical field. There are quite a lot of known hybrid materials of PANI and other polymer systems with various synthetic polymers, which results in blends with various properties. The presented research covers the blends of polyaniline with semisynthetic (carboxymethyl) cellulose (CMC). The system could lead to a new antielectrostatic material with interesting properties and seems to be applicable as an additive for packaging in both food and non-food industry. The final material was obtained using both protonated (HCl) and deprotonated form of polyaniline in its semi-oxidized form of leucoemeraldine. Blending consisted in obtaining of thin layer by slow evaporation of the solvent from a mixture of PANI and CMC. For the main investigation atomic force microscopy (AFM) in non-contact mode was used, which gave the topological information about the surface and also some structural information about the material. The described process seems to be very interesting as a route for obtaining a new hybrid natural/synthetic material with very interesting properties and a potential for application.     

A method for forecasting defect backlog in large streamline software development projects and its industrial evaluation

ContextPredicting a number of defects to be resolved in large software projects (defect backlog) usually requires complex statistical methods and thus is hard to use on a daily basis by practitioners in industry. Making predictions in simpler and more robust way is often required by practitioners in software engineering industry.ObjectiveThe objective of this paper is to present a simple and reliable method for forecasting the level of defect backlog in large, lean-based software development projects.MethodThe new method was created as part of an action research project conducted at Ericsson. In order to create the method we have evaluated multivariate linear regression, expert estimations and analogy-based predictions w.r.t. their accuracy and ease-of-use in industry. We have also evaluated the new method in a life project at one of the units of Ericsson during a period of 21 weeks (from the beginning of the project until the release of the product).ResultsThe method for forecasting the level of defect backlog uses an indicator of the trend (an arrow) as a basis to forecast the level of defect backlog. Forecasts are based on moving average which combined with the current level of defect backlog was found to be the best prediction method (Mean Magnitude of Relative Error of 16%) for the level of future defect backlog.ConclusionWe have found that ease-of-use and accuracy are the main aspects for practitioners who use predictions in their work. In this paper it is concluded that using the simple moving average provides a sufficiently-good accuracy (much appreciated by practitioners involved in the study). We also conclude that using the indicator (forecasting the trend) instead of the absolute number of defects in the backlog increases the confidence in our method compared to our previous attempts (regression, analogy-based, and expert estimates).     

Manganese-Labeled Alginate Hydrogels for Image-Guided Cell Transplantation

Cell transplantation has been studied extensively as a therapeutic strategy for neurological disorders. However, to date, its effectiveness remains unsatisfactory due to low precision and efficacy of cell delivery; poor survival of transplanted cells; and inadequate monitoring of their fate in vivo. Fortunately, different bio-scaffolds have been proposed as cell carriers to improve the accuracy of cell delivery, survival, differentiation, and controlled release of embedded stem cells. The goal of our study was to establish hydrogel scaffolds suitable for stem cell delivery that also allow non-invasive magnetic resonance imaging (MRI). We focused on alginate-based hydrogels due to their natural origin, biocompatibility, resemblance to the extracellular matrix, and easy manipulation of gelation processes. We optimized the properties of alginate-based hydrogels, turning them into suitable carriers for transplanted cells. Human adipose-derived stem cells embedded in these hydrogels survived for at least 14 days in vitro. Alginate-based hydrogels were also modified successfully to allow their injectability via a needle. Finally, supplementing alginate hydrogels with Mn ions or Mn nanoparticles allowed for their visualization in vivo using manganese-enhanced MRI. We demonstrated that modified alginate-based hydrogels can support therapeutic cells as MRI-detectable matrices.     

The {alpha}/{beta} hydrolase fold

We have identified a new protein fold—the /ßhydrolase fold—that is common to several hydrolytic enzymesof widely differing phylogenetic origin and catalytic function.The core of each enzyme is similar: an /ß sheet, notbarrel, of eight ß-sheets connected by -helices. Theseenzymes have diverged from a common ancestor so as to preservethe arrangement of the catalytic residues, not the binding site.They all have a catalytic triad, the elements of which are borneon loops which are the best-conserved structural features inthe fold. Only the histidine in the nucleophile-histidine-acidcatalytic triad is completely conserved, with the nucleophileand acid loops accommodating more than one type of amino acid.The unique topological and sequence arrangement of the triadresidues produces a catalytic triad which is, in a sense, amirror-image of the serine protease catalytic triad. There arenow four groups of enzymes which contain catalytic triads andwhich are related by convergent evolution towards a stable,useful active site: the eukaryotic serine proteases, the cysteineproteases, subtilisins and the /ß hydrolase fold enzymes.     

Vaporization Studies of the La2O3–Ga2O3 System

The vaporization of the samples of the compositions Ga₂O₃+ LaGaO₃, LaGaO₃+ La₄Ga₂O₉, and La₄Ga₂O₉+ La₂O₃ was investigated using Knudsen effusion mass spectrometry in the temperature range 1494–1937 K. The partial pressures of the gaseous species O₂, Ga, GaO, Ga₂O, and LaO were determined over the samples investigated. The equilibrium partial pressures were used for the calculation of the thermodynamic activities of the components at 1700 K. Gibbs energies of formation of LaGaO₃( s ) and La₄Ga₂O₉( s ) at 1700 K from the component oxides were derived from the thermodynamic activities as −46.4 ± 4.7 and −99.2 ± 7.9 kJ·mol⁻¹, respectively. The results were compared with the literature data obtained using other methods.     

Rare-earth ion doped up-conversion materials for photovoltaic applications

With the aim of utilizing the infrared region of solar radiation to improve solar cell performance, significant progress, including theoretical analysis and experimental achievement, has been made in the field of up-conversion for photovoltaic applications. This Research News article reviews recent progress in the development of rear-earth (RE) ion doped up-conversion materials for solar cell applications. In addition, new trends for RE-ion-doped phosphors are briefly discussed, among them trivalent RE-ion-doped up-conversion materials for organic solar cell applications.     

Effective Ligand Engineering of the Cu2ZnSnS4 Nanocrystal Surface for Increasing Hole Transport Efficiency in Perovskite Solar Cells

Effective engineering of surface ligands in semiconductor nanocrystals can facilitate the electronic interaction between the individual nanocrystals, making them promising for low‐cost optoelectronic applications. Here, the use of high purity Cu₂ZnSnS₄ (CZTS) nanocrystals as the photoactive layer and hole‐transporting material is reported in low‐temperature solution‐processed solar cells. The high purity CZTS nanocrystals are prepared by engineering the surface ligands of CZTS nanocrystals, capped originally with the long‐chain organic ligand oleylamine. After ligand removal, CZTS nanocrystals show substantial improvement in photoconductivity and mobility, displaying also an appreciable photoresponse in a simple heterojunction solar cell architecture. More notably, CZTS nanocrystals exhibit excellent hole‐transporting properties as interface layer in perovskite solar cells, yielding power conversion efficiency (PCE) of 15.4% with excellent fill factor (FF) of 81%. These findings underscore the importance of removing undesired surface ligands in nanocrystalline optoelectronic devices, and demonstrate the great potential of CZTS nanocrystals as both active and passive material for the realization of low‐cost efficient solar cells.     

Recovery of lanthanides from kola apatite in phosphoric acid manufacture

The paper presents the results of bench-scale studies for the recovery of lanthanides from Kola apatite in the phosphoric acid production by a two-stage hemihydrate-dihydrate wet-process. The second stage of the process (hydration of hemihydrate) provides the best conditions for the recovery of lanthanides. In the postulated recovery process use is made of solvent extraction for the removal of lanthanides during hydration of hemihydrate, and precipitation-stripping for the removal of lanthanides from the solvent. Lanthanides are recovered in the form of Ln-enriched concentrates with an efficiency of 80–85%. The process does not disturb the phosphoric acid production, and additionally purifies the by-product gypsum, so that it can be utilized.     

Robust and conventional neuropsychological norms: Diagnosis and prediction of age-related cognitive decline.

The aim of the study was to compare the performance of Robust and Conventional neuropsychological norms in predicting clinical decline among healthy adults and in mild cognitive impairment (MCI). The authors developed Robust baseline cross sectional and longitudinal change norms from 113 healthy participants retaining a normal diagnosis for at least 4 years. Baseline Conventional norms were separately created for 256 similar healthy participants without follow-up. Conventional and Robust norms were tested in an independent cohort of longitudinally studied healthy (n=223), MCI (n=136), and Alzheimer's disease (AD, n=162) participants; 84 healthy participants declined to MCI or AD (NL→DEC), and 44 MCI declined to AD (MCI→AD). Compared to Conventional norms, baseline Robust norms correctly identified a higher proportion of NL→DEC with impairment in delayed memory and attention-language domains. Both norms predicted decline from MCI→AD. Change norms for delayed memory and attention-language significantly incremented baseline classification accuracies. These findings indicate that Robust norms improve identification of healthy individuals who will decline and may be useful for selecting at-risk participants for research studies and early interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

System Dynamics (SD) -based concession pricing model for PPP highway projects

The design of concession price is essential to financial viability of Public–Private Partnership (PPP) highway projects. It is one of the most important variables that need to be determined during the negotiation period. However, there are few methods available for calculating the value of this variable. Research described in this paper aims to develop a reliable, objective, and systematic model for determining a rational concession price for PPP highway projects based on pro forma financial statements developed during the feasibility study period. The pricing parameters and price risk factors of PPP highway project were first identified and compiled through a comprehensive literature review. A concession pricing model using System Dynamics technique was then developed based on concession pricing parameters and the effectiveness of the proposed SD-based concession pricing model was verified by a real toll tunnel project located in China. The test result shows that the proposed model is reliable, accurate, and suitable for the application by practitioners for concession price determination. To overcome the effect of risk factors on concession price, a pricing adjustment model using Case-base Reasoning (CBR) technique was proposed to consider the unquantifiable risk factors. It is believed that a rational and practical concession pricing model can create a ‘win–win’ situation for both the private investor and the host government. This research framework can also be used as a reference to study other facilities' pricing models.