Possibility of a magnetic transition in Ce alloys

The fact that divalent rare earth impurities have a strong effect in lowering the α-γ transition temperature in Ce, allows the γ phase to become stable at low temperature without much change in its physical properties. The assumption that in this way an ordering (Néel) temperature can be reached, plus a thermodynamical analysis of the electronic transformation that takes place at the α-γ transition, leads to the prediction of a phase diagram for these alloys similar to that found in Cr doped V₂O₃.     

Current strategies for electrochemical detection of DNA with solid electrodes

A review of current strategies aimed at detecting nucleic acids (NA) using NA-modified solid electrodes reveals the versatility and potential of electrochemical detection in this field. What emerged at the beginning of 90s as a very promising detection system in DNA technology is now resulting in the first commercial devices. Many aspects of the experimental design, for example surface immobilisation and detection schemes, are outlined and evaluated. Although most approaches use hybridisation as the recognition reaction, those not based on hybridisation are also included. As is finally shown, great advances have been achieved, although further developments are required if electrochemical devices are to be suitable for routine measurement.Abbreviations A Adenine - a.c.V Alternating current voltammetry - Amp. Amperometry - Apo E Apolipoprotein E - BCB Brilliant cresyl blue - BLM Bilayer lipid membrane - bp Base pairs - BPPG Basal planar pyrolytic graphite - bpy 2,2-Bipyridine - C Cytosine - CMV Citomegalovirus - CPE Carbon paste electrode - CPSA Constant-current chronopotentiometric stripping analysis - Cronoamp. Chronoamperometry - CSPE Carbon screen-printed electrode - CV Cyclic voltammetry - dmb 4,4-Dimethyl-2,2-bipyridine - dmphen Dimethylphenanthroline - DPPZ Dipyrido[3,2-a.2,3-c]phenazine - DPV Differential pulse voltammetry - dsDNA Double-stranded DNA - EtBr Ethidium bromide - Fc Ferrocene - Fc-CA Ferrocenecarboxaldehyde - Fc-CTPPZ Di[1-ferrocenecarbamoylpropyl)tetrahydropyrazine-4-(propylcarbamoylpyridine)]phenazine - Fc-NH₂ Aminoferrocene - FET Field-effect transistor - G Guanine - GCE Glassy carbon electrode - HBV Hepatitis B virus - HGH1 Human growth hormone 1 - HIV Human immunodeficiency virus - HRP Horseradish peroxidase - HOPGE Highly oriented pyrolytic graphite electrode - IPA Intermittent pulse amperometry - ISFET Ion-selective field-effect transistor - ITO Tin-doped indium oxide electrode - LSV Linear sweep voltammetry - Nano-Au Au nanoparticles - NMP Nucleotide monophosphate - ODN Oligodeoxynucleotide - ox. Oxidation - PCR Polymerase chain reaction - PET Poly(ethylene terephthalate) - PGE Pyrolytic graphite electrode - phen 1,10-Phenanthroline - PNA Peptide nucleic acid - Ppy Polypyrrole - (PQQ)GDH Pyrroline quinone glucose dehydrogenase - red. Reduction - SAM Self-assembled monolayer - SBP Soybean peroxidase - SNP Single nucleotide polymorphism - ssDNA Single-stranded DNA - SWV Square-wave voltammetry - T Thymine - Th Thionine - TTV TT virus - Ep Difference of peak potential     

A new fluoride selective electrochemical and fluorescent chemosensor based on a ferrocene-naphthalene dyad

A new difunctionalized receptor based on an aza-ferrocenophane structure shows electrochemical and fluorescent responses to fluoride anion.     

Objective estimates of cochlear tuning by otoacoustic emission analysis

A new method is presented for estimating cochlear tuning starting from measurements of either the transient evoked otoacoustic emission latency or the spontaneous otoacoustic emission minimal spacing. This method could be useful in obtaining indirect information about the tuning curve, particularly for subjects that, like neonates, cannot be studied with psycho-acoustical techniques. Theoretical models of the acoustic transmission along the cochlea based on the transmission line formalism predict a relation between the otoacoustic emission latency and the frequency. This relation depends on the tuning curve, i.e., the frequency dependence of the quality factor of the cochlear resonances. On the other hand, models for the generation of spontaneous emissions based on the concept of coherent scattering from cochlear random inhomogeneities imply an independent relation between the tuning curve and the minimal frequency spacing between spontaneous emissions. In this study, experimental measurements of the otoacoustic emission latency and of the minimal spacing between spontaneous emissions are presented. Theoretical relations are derived, which connect these two measured quantities and the tuning curve. The typically longer latency of neonates implies a higher degree of tuning at high levels of stimulation.     

Cobalt(II) and iron(III) complexes with 2-substituted benzimidazole derivatives

Summary FeCl₃ and the primary amines 2-aminobenzimidazole (abi) and 2(2-aminophenyl)benzimidazole (apbi) give complexes for which spectroscopic and magnetic data suggest a pentacoordinate [FeCl₄].The reactions of complexes of primary amines of CoCl₂ and FeCl₃ with the carbonyl compounds acetylacetone (Hacac) and pyridylcarbaldehyde (pyc) yield complexes which contain the Schiff bases from the condensation of the amines and the carbonyl groups.Analytical data indicate formulae [CoCl₂(abiacac)₂], [CoCl₂(abipyc)], [FeCl₃(abiacac)], [FeCl₃(abipyc)₂] and [FeCl₃(apbipyc)] for the complexes. The cobalt(II) complexes are pseudo-tetrahedral, while the iron complexes are tetra-, penta-, or hexa-coordinate, as deduced from spectroscopic and magnetic measurements.     

Electromagnetic momentum in frontiers of modern physics

We review the role of the momentum of the electromagnetic (EM) fields P _e in several areas of modern physics. P _e represents the EM interaction in equations for matter and light waves propagation. As an application of wave propagation properties, a first order optical experiment which tests the speed of light in moving rarefied gases is presented. Within a classical context, the momentum P _e appears also in proposed tests of EM interactions involving open currents and angular momentum conservation laws. Moreover, P _e is the link to the unitary vision of the quantum effects of the Aharonov-Bohm (AB) type and, for several of these effects, the strength of P _e is evaluated. These effects provide a quantum approach to evaluate the limit of the photon mass m _ph. A new effect of the AB type, together with the scalar AB effect, provides the basis for table-top experiments which yield the limit m _ph = 9.4 × 10⁻⁵²g, a value that improves the results achieved with recent classical and quantum approaches.      

Design of progressively censored group sampling plans for Weibull distributions: An optimization problem

Optimization algorithms provides efficient solutions to many statistical problems. Essentially, the design of sampling plans for lot acceptance purposes is an optimization problem with several constraints, usually related to the quality levels required by the producer and the consumer. An optimal acceptance sampling plan is developed in this paper for the Weibull distribution with unknown scale parameter. The proposed plan combines grouping of items, sudden death testing in each group and progressive group removals, and its decision criterion is based on the uniformly most powerful life test. A mixed integer programming problem is first solved for determining the minimum number of failures required and the corresponding acceptance constant. The optimal number of groups is then obtained by minimizing a balanced estimation of the expected test cost. Excellent approximately optimal solutions are also provided in closed-forms. The sampling plan is considerably flexible and allows to save experimental time and cost. In general, our methodology achieves solutions that are quite robust to small variations in the Weibull shape parameter. A numerical example about a manufacturing process of gyroscopes is included for illustration.