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Detection of relevant contaminants using screening approaches is a key issue to ensure food safety and respect for the regulatory limits established. Electrochemical sensors present several advantages such as rapidity; ease of use; possibility of on-site analysis and low cost. The lack of selectivity for electrochemical sensors working in complex samples as food may be overcome by coupling them with molecularly imprinted polymers (MIPs). MIPs are synthetic materials that mimic biological receptors and are produced by the polymerization of functional monomers in presence of a target analyte. This paper critically reviews and discusses the recent progress in MIP-based electrochemical sensors for food safety. A brief introduction on MIPs and electrochemical sensors is given; followed by a discussion of the recent achievements for various MIPs-based electrochemical sensors for food contaminants analysis. Both electropolymerization and chemical synthesis of MIP-based electrochemical sensing are discussed as well as the relevant applications of MIPs used in sample preparation and then coupled to electrochemical analysis. Future perspectives and challenges have been eventually given.  相似文献   
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In this paper we show that, for a sub-Laplacian Δ on a 3-dimensional manifold M, no point interaction centered at a point q0M exists. When M is complete w.r.t. the associated sub-Riemannian structure, this means that Δ acting on C0(M?{q0}) is essentially self-adjoint in L2(M). A particular example is the standard sub-Laplacian on the Heisenberg group. This is in stark contrast with what happens in a Riemannian manifold N, whose associated Laplace-Beltrami operator acting on C0(N?{q0}) is never essentially self-adjoint in L2(N), if dim?N3. We then apply this result to the Schrödinger evolution of a thin molecule, i.e., with a vanishing moment of inertia, rotating around its center of mass.  相似文献   
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Frascaria  Dario  Olver  Neil 《Mathematical Programming》2022,192(1-2):177-206
Mathematical Programming - Flows over time have received substantial attention from both an optimization and (more recently) a game-theoretic perspective. In this model, each arc has an associated...  相似文献   
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The thermal fractionation kinetics of a linear low‐density polyethylene (LLDPE) during Successive Self‐Nucleation and Annealing (SSA) is investigated by fast scanning chip‐calorimetry (FSC), by systematically varying the holding times (ts) at each fractionation temperature (Ts). The range of explored fractionation times spans four orders of magnitude, from 0.001 to 10 s. Discernible thermal fractions are already detected in the very early stages of the process, at ts shorter than one second. As ts increases, the melting endotherm after SSA indicates a progressive lamellar thickening and narrowing of the thicknesses distribution of the various crystalline fractions. The largest variations are observed for the families of crystals containing the longest crystallizable sequences, which also undergo a change of their relative content as a consequence of self‐nucleated crystallization at Ts. The quality of the thermal fractionation obtained in 10 seconds with FSC is equivalent to that of conventional differential scanning calorimetry SSA (ts = 300 s). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2200–2209  相似文献   
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The structures and solid-state dynamics of the supramolecular salts of the general formula [(12-crown-4)2 ⋅ DABCOH2](X)2 (where DABCO=1,4-diazabicyclo[2.2.2]octane, X=BF4, ClO4) have been investigated as a function of temperature (from 100 to 360 K) and pressure (up to 3.4 GPa), through the combination of variable-temperature and variable-pressure XRD techniques and variable-temperature solid-state NMR spectroscopy. The two salts are isomorphous and crystallize in the enantiomeric space groups P3221 and P3121. All building blocks composing the supramolecular complex display dynamic processes at ambient temperature and pressure. It has been demonstrated that the motion of the crown ethers is maintained on lowering the temperature (down to 100 K) or on increasing the pressure (up to 1.5 GPa) thanks to the correlation between neighboring molecules, which mesh and rotate in a concerted manner similar to spiral gears. Above 1.55 GPa, a collapse-type transition to a lower-symmetry ordered structure, not attainable at a temperature of 100 K, takes place, proving, thus, that the pressure acts as the means to couple and decouple the gears. The relationship between temperature and pressure effects on molecular motion in the solid state has also been discussed.  相似文献   
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