Indistinguishable particles and hidden variables

An axiomatics for the indistinguishability of elementary particles in terms of hidden variables is presented in a manner which depart from the standard approaches usually given to hidden variables. Quantum distribution functions are also discussed and some possible related lines of work are suggested.     

Determination of bismuth by selenious acid

Summary Bismuth is shown to be precipitated quantitatively as bismuth selenite by boiling an almost neutral solution of bismuth nitrate and excess selenious acid. The excess H₂SeO₃ is determined iodometrically by standard thiosulphate or arsenious oxide solution. Alternatively, the precipitated selenite may be dried at 105–110° C and weighed as Bi₂(SeO₃)₃.Sincere thanks of the authors are due to Prof. S. S. Joshi for research facilities and to Dr. G. S. Deshmukh for keen interest in the work.     

Microgram determination of vanadium from natural resources

Vanadium has been extracted and determined from a number of natural resources by liquid-liquid extraction technique using N-m-tolyl-o-methoxybenzohydroxamic acid.     

Enhancing the inclusion of non-discretionary inputs in DEA

The aim of this paper is to provide an alternative approach for estimating efficiency when a set of decision-making units uses non-discretionary inputs in the productive process. To test the influence of these variables, our proposal uses a multi-stage approach based on Tobit regressions. In order to avoid potential bias, a bootstrap procedure is used to estimate these regressions. This methodology allows enhancing other models previously proposed to introduce non-controllable inputs in data envelopment analysis (DEA) overcoming, thus, some of their main shortcomings. We illustrate our framework with an empirical application on Spanish high schools where non-controllable factors play a major role to explain educational achievements.     

Interaction-Free Measurement with Matter Waves

In the early 1990′s, A. Elitzur and L. Vaidman proposed an interaction-free measurement (IFM) that allows researchers to find infinitely fragile objects without destroying them. But the Elitzur-Vaidman IFM has been used only to determine the position of opaque objects. We propose a non-trivial extension of such a technique with matter waves, which allows measurement of classical fields. And we show severe limitations when we talk about gravitational fields.     

Determination of zirconium in U−Zr−Al and Pu−Zr−Al alloys by isotope dilution thermal ionization mass spectrometry

An isotope dilution thermal ionization mass-spectrometric (ID-TIMS) method is described for the determination of Zr in U?Zr?Al and Pu?Zr?Al alloy samples. Problems encountered in the chemical exchange between the zirconium isotopes in the spike and sample, particularly Pu?Zr?Al samples, are discussed and a method has been standardized to eliminate it. Separation of Zr from U, Pu and Al was achieved by employing ion exchange procedures. A precision of better than 1% is possible in the determination of Zr with the method reported here.     

Gravimetric estimation of bismuth as bismuthyl dichromate

Summary Conditions are described for the quantitative precipitation of bismuthyl dichromate, (BiO)₂Cr₂O₇, and the suitability of this reaction for the gravimetric estimation of bismuth is shown. The use of arsenious oxide as a primary standard for the iodometric titration of excess chromate is emphasised.Sincere thanks of the authors are due to Prof. S. S. Joshi for research facilities and to Dr. G. S. Deshmukh for keen interest in the work.     

Thermo-optical properties of silver and gold nanofluids

This work focuses on the study of thermal diffusivity and physical properties of nanofluids with very low concentrations of silver or gold nanoparticles. Thermal measurements were performed by means of thermal lens spectroscopy in the dual beam configuration. Improvements of 20 and 16 % in the thermal diffusivity were observed for silver and gold nanofluids, respectively, in comparison with pure water. The estimation of the size distribution of the metallic nanoparticles was obtained through the fitting of the extinction spectra via Mie theory and images of field emission gun scanning electron microscopy.     

Reconfigurable T-junction DNA Origami

DNA self-assembly allows the construction of nanometre-scale structures and devices. Structures with thousands of unique components are routinely assembled in good yield. Experimental progress has been rapid, based largely on empirical design rules. Herein, we demonstrate a DNA origami technique designed as a model system with which to explore the mechanism of assembly. The origami fold is controlled through single-stranded loops embedded in a double-stranded DNA template and is programmed by a set of double-stranded linkers that specify pairwise interactions between loop sequences. Assembly is via T-junctions formed by hybridization of single-stranded overhangs on the linkers with the loops. The sequence of loops on the template and the set of interaction rules embodied in the linkers can be reconfigured with ease. We show that a set of just two interaction rules can be used to assemble simple T-junction origami motifs and that assembly can be performed at room temperature.     

Geometric scaling effects on instrumental plate height in field flow fractionation

This paper examines geometric scaling models for field flow fractionation systems to understand how channel dimensions affect resolution and retention. Specifically, the changing contribution of the instrumental plate height during miniaturization of field flow fractionation (FFF) systems is reported. The work is directed towards determining the optimal geometrical parameters for miniaturization of field flow fractionation systems. The experimental relationship between channel height in FFF systems and instrumental plate heights is reported. FFF scaling models are modified to: (i) better clarify the dependence of plate height and resolution on channel height in FFF and (ii) include a more complete geometrical scaling analysis and model comparison in the low retention regime. Electrical field flow fractionation has been shown to benefit from miniaturization, so this paper focuses on that subtype, but surprisingly, the results also indicate the possibility of improvement in performance with miniaturization of other field flow fractionation systems including general FFF subtypes in which the applied field does not vary with channel height. This paper also discusses the potential role of more powerful microscale field flow fractionation systems as a new class of sample preparation units for micro-total-analysis systems (mu-TAS).