Nanotechnologies have reached maturity and market penetration that require nano‐specific changes in legislation and harmonization among legislation domains, such as the amendments to REACH for nanomaterials (NMs) which came into force in 2020. Thus, an assessment of the components and regulatory boundaries of NMs risk governance is timely, alongside related methods and tools, as part of the global efforts to optimise nanosafety and integrate it into product design processes, via Safe(r)‐by‐Design (SbD) concepts. This paper provides an overview of the state‐of‐the‐art regarding risk governance of NMs and lays out the theoretical basis for the development and implementation of an effective, trustworthy and transparent risk governance framework for NMs. The proposed framework enables continuous integration of the evolving state of the science, leverages best practice from contiguous disciplines and facilitates responsive re‐thinking of nanosafety governance to meet future needs. To achieve and operationalise such framework, a science‐based Risk Governance Council (RGC) for NMs is being developed. The framework will provide a toolkit for independent NMs' risk governance and integrates needs and views of stakeholders. An extension of this framework to relevant advanced materials and emerging technologies is also envisaged, in view of future foundations of risk research in Europe and globally. 相似文献
Tabular representations have been proposed for structuring complex mathematical expressions as they appear in the specification of programs. We argue that tables not only help in writing and checking complex expressions, but also in their formal manipulation. More specifically, we explore the use of tabular predicates and tabular relations in program verification and refinement. 相似文献
We present a calibration method which allows single shot dual wavelength online shape measurement in a disturbed environment. Effects of uncontrolled carrier frequency filtering are discussed as well. We demonstrate that phase maps and speckle displacements can be recovered free of chromatic aberrations. To our knowledge, this is the first time that a single shot dual wavelength calibration is reported by defining a criteria to make the spatial filtering automatic avoiding the problems of manual methods. The procedure is shown to give shape accuracy of 35 µm with negligible systematic errors using a synthetic wavelength of 1.1 mm. 相似文献
Six standard clays, before and after calcination at 3 or 4 temperatures and being mixed with Ca(OH)2 [CH] in the presence of simulated cement pore solution, and with ordinary Portland cement, respectively, were studied in detail. Chemical compositions of most clays conform well to the requirement in ASTM C 618. Water demand of clay-containing mortar varies, depending on the crystal chemistry of raw clays, and on the specific surface area of calcined clays. Measurements of XRD background or alkali soluble Si are rapid methods in evaluation of the pozzolanic activity of clays. Compressive strength of mortars based on the raw clays is affected by structure of clays. Calcination increases the pozzolanic activity of clays and the compressive strength of the Portland cement — clay mortars. A close correlation exists between compressive strength of mortars and particle size distribution of the dehydroxylated clays. The most common reaction products of clay — CH mixtures are C-S-H2 and C4AHx, while C2ASHj8 and C3AH6 were also detected with clays rich in Al. 相似文献
In mammalian cells, Sprecher has proposed that the synthesis of long-chain PUFA from the 20-carbon substrates involves two
consecutive elongation steps, a Δ6-desaturation step followed by retroconversion (Sprecher, H., Biochim. Biophys. Acta 1486, 219–231, 2000). We searched the database using the translated sequence of human elongase ELOVL5, whose encoded enzyme elongates
monounsaturated and polyunsaturated FA, as a query to identify the enzyme(s) involved in elongation of very long chain PUFA.
The database search led to the isolation of two cDNA clones from human and mouse. These clones displayed deduced amino acid
sequences that had 56.4 and 58% identity, respectively, to that of ELOVL5. The open reading frame of the human clone (ELOVL2)
encodes a 296-amino acid peptide, whereas the mouse clone (Elovl2) encodes a 292-amino acid peptide. Expression of these open
reading frames in baker's yeast, Saccharomyces cerevisiae, demonstrated that the encoded proteins were involved in the elongation of both 20-and 22-carbon long-chain PUFA, as determined
by the conversion of 20∶4n−6 to 22∶4n−6, 22∶4n−6 to 24∶4n−6, 20∶5n−3 to 22∶5n−3, and 22∶5n−3 to 24∶5n−3. The elongation activity
of the mouse Elovl2 was further demonstrated in the transformed mouse L cells incubated with long-chain (C20-and C22-carbon) n−6 and n−3 PUFA substrates by the significant increase in the levels of 24∶4n−6 and 24∶5n−3, respectively. This
report demonstrates the isolation and identification of two mammalian genes that encode very long chain PUFA specific elongation
enzymes in the Sprecher pathway for DHA synthesis. 相似文献
The electrosorption properties of p-norborn-2-yl phenolate ions in alkaline solutions were investigated by ac polarographic and electrocapillary measurements.
Two adsorption regions were found. At low bulk surfactant concentrations the adsorption at the positively charged electrode (−0.2 E −0.6 V) is predominant while at higher surfactant concentrations the adsorption at the negatively charged electrode (−0.6 E −1.0 V) is more pronounced. At E = −0.40 V the adsorption parameters were determined (a ≈ 2; ΔG°A = −32.5 ± 1 kJ mol−1. Between −0.6 E −1.0 V one potential of maximum adsorption for all concentrations does not exist and therefore the adsorption parameters could not be calculated.
At E = −0.40 V progressive two-dimensional nucleation with a nucleation order of 3 was observed which corresponds well with the high attraction constant.
The electrode reaction S2O2−8 + 2e− → 2 SO2−4 is inhibited by norborn-2-yl phenolate ions in the potential range −0.2 E −0.6 V. In the second potential range of capacity decrease the electrode process is much less retarded. At E = −0.40 V, in a similar manner as described for neutral molecules, a linear dependence of the log ks (ks apparent rate constant) on ln cA and π (π = surface film pressure), respectively, has been found. 相似文献
At present, even though most cement plants are computer controlled, they depend on manual particle analysis and feed settings. Automatic process control through the use of continuous particle size analysis can provide the maximum obtainable throughput at optimum particle size. A new particle size measurement technology using a helium-neon laser and a unique optical filtering system has been reported previously. Fourier diffraction patterns of particles in the 2176 micron range are utilized to produce a 13 channel histogram of the complete particle size distribution. The histogram data are used to compute many parameters of the size distribution, such as, equivalent surface area, median, mean, and percent passing a number of micron sizes. A family of particle size instrumentation has been developed using this technology for both off-line quality control and on-line process control. The design of this equipment and its operation is described. In addition, experimental data are presented comparing the fineness measurements of Portland cement obtained by air permeability apparatus and those of the MICROTRACTM equipment. 相似文献
This paper proposes new stability analysis and convergence results applied to the Iterative Feedback Tuning (IFT) of a class of Takagi–Sugeno–Kang proportional-integral-fuzzy controllers (PI-FCs). The stability analysis is based on a convenient original formulation of Lyapunov’s direct method for discrete-time systems dedicated to discrete-time input affine Single Input-Single Output (SISO) systems. An IFT algorithm which sets the step size to guarantee the convergence is suggested. An inequality-type convergence condition is derived from Popov’s hyperstability theory considering the parameter update law as a nonlinear dynamical feedback system in the parameter space and iteration domain. The IFT-based design of a low-cost PI-FC is applied to a case study which deals with the angular position control of a direct current servo system laboratory equipment viewed as a particular case of input affine SISO system. A comparison of the performance of the IFT-based tuned PI-FC and the performance of the PI-FC tuned by an evolutionary-based optimization algorithm shows the performance improvement and advantages of our IFT approach to fuzzy control. Real-time experimental results are included. 相似文献