A discrete-time chaos synchronization system for electronic locking devices

This paper presents a novel electronic locking key based on discrete-time chaos synchronization. Two Chen chaos generators are synchronized using the Model-Matching Approach, from non-linear control theory, in order to perform the encryption/decryption of the signal to be transmitted. A model/transmitter system is designed, generating a key of chaotic pulses in discrete-time. A plant/receiver system uses the above mentioned key to unlock the mechanism. Two alternative schemes to transmit the private chaotic key are proposed. The first one utilizes two transmission channels. One channel is used to encrypt the chaotic key and the other is used to achieve output synchronization. The second alternative uses only one transmission channel for obtaining synchronization and encryption of the chaotic key. In both cases, the private chaotic key is encrypted again with chaos to solve secure communication-related problems. The results obtained via simulations contribute to enhance the electronic locking devices.     

Simultaneous Electrochemical Determination of Paracetamol and Allura Red in Pharmaceutical Doses and Food Using a Mo(VI) Oxide-Carbon Paste Microcomposite

This work presents a new application for MoO₃ combined with carbon paste to prepare a microcomposite electrode (Mo(VI)_Ox/CPE) for the simultaneous determination of paracetamol (PCM) and Allure Red (AR) by square-wave voltammetry (SWV). The anodic peak currents for PCM and AR were 70.0 and 80.0 % high compared with an unmodified carbon paste electrode. The surface areas of Mo(VI)_Ox/CPE and CPE were evaluated by cyclic voltammetry. The detection limit were 0.14 and 0.38 μmol/L for PCM and AR respectively. The relative standard deviations (RSDs) were 2.0 % (n=7). Stability, shelf life and possible interferences were also evaluated with very acceptable results.     

Development of new amphiphilic bio-organic assemblies for potential applications in iron-binding and targeting tumor cells

Iron overload has been implicated in the pathogenesis of many neurodegenerative diseases, cancer and thalassemia. In this work, we have developed new supramolecular assemblies as potential iron chelators for mitigating iron overload at the cellular level. We utilized fluorenyl-based building blocks that were functionalized with ethylene diamine (Fmoc-Ed) or arginine (Fmoc-Arg). Fmoc-Ed was further conjugated with ureido propionic acid (UDP) or pyrazole-3-carboxylic acid (PCA). Each of the building blocks were self-assembled into nanovesicles or fibers and further functionalized with the transferrin receptor binding peptide THRPPMWSPVWP (Tf) to promote receptor mediated cellular uptake. Our results indicated that the assemblies were able to target HeLa cells, induce apoptosis, ROS formation and were able to penetrate the cells. The degree of cellular impact was dependent upon the structure of the assemblies. The effects were more prominent under iron overload conditions compared to normal growth conditions. Our results suggest that such nanoscale assemblies may open new avenues for further studies into iron chelation and mitigation of iron overload using Fmoc-functionalized building blocks.     

Meteoric 10Be concentrations in the center of Mexico

Journal of Radioanalytical and Nuclear Chemistry - The 1MV AMS system installed at National Accelerator Mass Spectrometry Laboratory (LEMA) has been used to determine the meteoric 10Be...     

Influence of crystallographic orientation of biogenic calcite on in situ Mg XANES analyses

Micro X‐ray absorption near‐edge spectroscopy at the Mg K‐edge is a useful technique for acquiring information about the environment of Mg²⁺ in biogenic calcite. These analyses can be applied to shell powders or intact shell structures. The advantage of the latter is that the XANES analyses can be applied to specific areas, at high (e.g. micrometre) spatial resolution, to determine the environment of Mg²⁺ in a biomineral context. Such in situ synchrotron analysis has to take into account the potential effect of crystallographic orientation given the anisotropy of calcite crystals and the polarized nature of X‐rays. Brachiopod shells of species with different crystallographic orientations are used to assess this crystallographic effect on in situ synchrotron measurements at the Mg K‐edge. Results show that, owing to the anisotropy of calcite, in situ X‐ray absorption spectra (XAS) are influenced by the crystallographic orientation of calcite crystals with a subsequent potentially erroneous interpretation of Mg²⁺ data. Thus, this study demonstrates the importance of crystallography for XAS analyses and, therefore, the necessity to obtain crystallographic information at high spatial resolution prior to spectroscopic analysis.     

Two-dimensional MHD simulation of isothermal plasma armatures

The authors report results on the use of a two-dimensional resistive MHD code to simulate the internal dynamics in a railgun plasma armature, starting from a slightly perturbed equilibrium initial state. The plasma temperature, conductivity, and ionization fractions are treated as uniform in space and constant in time. The rear of the plasma is in contact with a low-pressure nonconducting gas. A finite-difference, explicit, Eulerian, flux-corrected transport code is used to advance all quantities in time. The computation grid has 200 cells parallel to the rails, and 20 across the rails. The results show the growth and subsequent shedding of the plasma mass toward the nonconducting region at the rear. The mass lost is not replenished and the armature becomes shorter, with steeper pressure and magnetic field profiles. The bulk of the profiles is not thoroughly disrupted, but behaves rather sturdily and seems to maintain a shape fairly close to the equilibrium profiles     

Highly selective reaction of alpha-halo-alpha,beta-unsaturated esters with ketones or aldehydes promoted by SmI2: an efficient alternative access to Baylis-Hillman adducts

A samarium diiodide promoted addition of aromatic or aliphatic beta-substituted-alpha-halo-alpha,beta-unsaturated esters 1 or 3 to both ketones (in THF) and aldehydes (in acetonitrile) led to (Z)-2-(1-hydroxyalkyl)-2,3-alkenoates 2 and 4 in good yields and very high stereoselectivity. This method constitutes an efficient and valuable alternative to the synthesis of Baylis-Hillman adducts. A mechanism is proposed to explain this transformation.