Retardation effect of jojoba chain length on the chemical reactivity of the liquid wax

Jojoba wax and its derivatives are slow-reacting compounds. To elucidate the reasons for this phenomenon, we reacted jojoba mono- and bis-epoxide and trans-jojoba bis-epoxide (C₃₈–C₄₄ long-chain esters), as well as side chain esters of three steroid skeleton mono-epoxide derivatives with NaI under acidic conditions to yield the corresponding iodohydrins, which then formed the respective bis-keto (or mono-ketone) derivatives. The kinetics, activation energies, and thermodynamic parameters of activation of nucleophilic epoxide opening and pinacol rearrangement were determined for all these compounds. The reaction rates of the jojoba derivatives were similar to those of two of the epoxides derived from the steroid skeleton compounds, and in the third case the steroid derivative reacted somewhat faster than all the rest. This pattern of rate retardation could stem either from folding of the long jojoba chain, resulting in steric hindrance around the reaction centers, or from repeated unproductive collisions along the long hydrocarbon chain of the jojoba wax (statistical effect). Our results appear to suggest that the multiple unsuccessful collisions were the dominant factor, although steric hindrance cannot be ruled out.     

Activity and stability of alumina zeolite nickel catalysts

The catalytic properties of nickel catalysts (50 wt.% of alumina and 50 wt.% of Ni,H-ZSM-5) were investigated and related to the amount of NiO (0–8 wt.%) and the method of nickel incorporation (8 wt.% NiO). Consideration was also given to the method by which zeolite and alumina were combined. The cracking properties of the catalysts increased when the amount of NiO was raised up to 4 wt.%. To decrease the content of aromatic hydrocarbons in the products it is necessary to raise the amount of NiO to a higher level than 4 wt.%. The catalyst prepared by peptisation of the mixture of zeolite and aluminium hydrogel (with ageing process) displayed reduced activity and stability because of the low susceptibility of NiO to reduction.     

Morphological instability of poly(ethylene terephthalate) cyclic oligomer crystals

The mechanism of formation of depressions and cavities in the middle of the basal faces of hexagonal plates of poly(ethylene terephthalate) oligomer single crystals upon growth during heat treatment is investigated. It is proposed that this effect is caused by two simultaneously occurring processes: supersaturation inhomogeneity in the centre of the plates and formation of the kinematic (shock) waves at the edges of the plates.     

Relationship of Physicochemical Characteristics with Sensory Profile of Cookies Enriched with Medicinal Herbs

In this work, a range of model cookies enriched with different quantities of medicinal herbs, applied in two forms (pulverized mixture and extract), were studied to compare and describe relationships between physicochemical and sensory data. Multivariate statistical methods were applied to estimate relationships in the analyzed data. Analysis of variance showed that the majority of analyzed parameters were highly significant in discriminating among the samples (p < 0.05), which supported the usefulness of their application in characterizing the quality profile of enriched cookies. Principal component analysis on physicochemical data revealed that cookies at the same enrichment level showed more similarities. Principal component analysis on sensory data exhibited a larger separation between the samples with increasing enrichment levels, especially in the case of pulverized herbal mixture. According to partial least squares regression, two significant partial least squares components explained 92.7% and predicted 78.0% variation in the data. The most important parameters in discriminating between the cookies enriched with medicinal herbs were lightness, red tonality, and hardness. The selected physicochemical parameters could be used in future studies to evaluate variously enriched cookies by establishing models and investigating the predictability of sensory quality.     

Injection of CO2 into saline formations: Benchmarking worldwide projects

Carbon capture, transport and storage (CCS) is a very active field of research, because of its potential to make large reductions of emissions from fossil fuel combustion relevant to climate change. This paper reviews the recent and current work on practical injections of CO₂ as research tests for storage projects and specifically focuses on industrial-scale or relevant injections into saline formations (about 1 Mt CO₂ per year). All injection projects around the world have been reviewed, and 20 are reported to compile, depth, reservoir quality and injectivity, cost, and rate. This shows that testing of injection is concentrated onshore; however the projects with the highest total CO₂ storage estimate are offshore. Pipeline transport systems are mostly used for the large projects. Formations targeted in the injection process are sandstone or carbonate. In the majority of cases initial projections of injectivity are confirmed in tests. A variety of monitoring techniques are used in all projects, these have detected CO₂, but have not shown unexpected CO₂ movement. Practical experiences of CO₂ injection operations therefore suggest that similar operations can be successfully carried out in the saline formations of the UK North Sea and other large sedimentary basins.     

Bioactive Titanium Surfaces Enriched with Silver Nanoparticles Through an In Situ Reduction: Looking for a Balance Between Cytocompatibility and Antibacterial Activity

This research aims toward an antibacterial and osteoconductive Ti₆Al₄V surface by chemical etching–oxidation treatment and in situ reduction of silver nanoparticles. Starting from a previously developed process, already proved to enhance the osteoinductive ability of titanium, different parameters are changed to tailor the amount of silver and its distribution across the surface oxide layer thickness. The samples are characterized by scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, release of silver, biofilm formation (Staphylococcus aureus), and cytocompatibility toward human osteoblasts progenitor cells. The total amount of silver in the surface oxide layer depends only on the concentration of the silver precursor. The time of the addition of the silver precursor, during the oxidation treatment, affects the oxide layer thickness, dimension, and distribution of the nanoparticles across the surface oxide: they are larger and accumulate on the outermost layer, if the addition occurs early. The maximum ion release occurs after 24 h and lasts up to 14 days; the later addition of silver precursors leads to sustaining the silver release for a longer time. The samples prepared with the higher concentration of the silver precursor are bactericide, but highly cytotoxic, whereas the other ones are bacteriostatic and moderately cytotoxic.     

Practical application of product design method robust to disturbances

Contemporary designed and manufactured products should meet a wide range of client requirements and expectations regarding quality for conditions of use in a life cycle. Therefore, design methods, which enable an optimal choice of product parameters by decreasing product sensivity to occurrence of some disturbances in a manufacturing process, become more and more significant in industrial practice. Such a behavior probably allows getting the lowest quality loss while keeping planned production costs. In this article, a new method of products design robust to disturbances exsisting in a technological process is presented. The application of mathematical modeling and methods of parameter estimation enabled formulating an approach in which parameters and acceptable tolerance of manufacturing product parameters are calculated. The efficiency of the proposed method was verified in the machine‐building industry with the example of designing parameters of a brushless direct current motor. © 2010 Wiley Periodicals, Inc.     

SLA-controlled interconnection charging in next generation networks

Next generation network (NGN) should facilitate a single party to establish quality of service (QoS) enabled path between the two IP providers mutually interconnected by one or more transit providers. For that purpose, an end-to-end service level agreement (SLA) should be negotiated and maintained. In this article, we propose interconnection charging, which is controlled by the end-to-end SLA. Relationships between the required, offered, and actually achieved inter-provider QoS are quantified through the degrees of offering and provisioning, at both end-to-end and per-domain levels. Nominal retail price offered to end users and interconnection costs related with particular SLA are then corrected if needed, depending on the offered and provisioned QoS levels. We further propose five policies for interconnection charging and compare them under different QoS provisioning scenarios. Results of the analysis indicate that a properly selected SLA-controlled interconnection charging policy should encourage providers: (1) to offer services with different QoS levels; (2) to offer service that perfectly or most approximately matches the required QoS and (3) to achieve the contracted QoS level.     

Denoising of multicomponent images using wavelet least-squares estimators

In this paper, we study denoising of multicomponent images. The presented procedures are spatial wavelet-based denoising techniques, based on Bayesian least-squares optimization procedures, using prior models for the wavelet coefficients that account for the correlations between the spectral bands. We analyze three mixture priors: Gaussian scale mixture models, Bernoulli-Gaussian mixture models and Laplacian mixture models. These three prior models are studied within the same framework of least-squares optimization. The presented procedures are compared to Gaussian prior model and single-band denoising procedures. We analyze the suppression of non-correlated as well as correlated white Gaussian noise on multispectral and hyperspectral remote sensing data and Rician distributed noise on multiple images of within-modality magnetic resonance data. It is shown that a superior denoising performance is obtained when (a) the interband covariances are fully accounted for and (b) prior models are used that better approximate the marginal distributions of the wavelet coefficients.     

Physicochemical and electrochemical properties of the carbon materials containing nitrogen and cobalt derived from acetonitrile and Co–Al layered double hydroxides

Two sets of the carbon materials containing nitrogen and cobalt were prepared by simultaneous carbonization of CH₃CN and decomposition of Co–Al layered double hydroxides (LDHs) (of Co/Al atomic ratios equal to 2 or 3) at 600, 700 and 800 °C followed by treatment with HCl. The physicochemical features of the samples were characterized by means of XRD, TG, EA, XPS, XRF, FT-IR, SEM, Raman spectroscopy and nitrogen sorption. All of the composites were active in oxygen reduction reaction (ORR) in alkaline medium. Their ORR behaviour was determined by the contribution of structural defects and N-doping in graphitic lattice. The beneficial effect of metallic cobalt encapsulated inside the N-CNTs on the ORR performance was also taken into consideration. The studies showed that the likelihood of the existence of Co–N–C species and their participation in ORR seemed to be suppressed by the formation of CoAl₂O₄. The samples prepared at 600 and 700 °C appeared to be more active in ORR than that obtained at 800 °C. The number of electrons involved in ORR (2.89, 2.82 and 2.77) decreased with increasing synthesis temperature for the samples prepared with LDHs of Co/Al?=?2 as a consequence of lowering concentration of nitrogen (3.2, 2.4 and 1.5 wt%), in particular diminishing contribution of pyridinic nitrogen, and decreasing exposure of graphitic edges (I_D1/I_G?~?2.6, 2.0 and 1.0). The ORR performance of the samples prepared with LDHs of Co/Al?=?3 is comparable to that of the corresponding samples prepared with LDHs of Co/Al?=?2.