Defects within the landau theory: A perturbation approach

We discuss the continuum medium theory that enables us to find the defect contribution to phase transition anomalies with the use of only a few phenomenological parameters. The theory is invalid in the immediate vicinity of the phase transition temperature and for high concentration of defects. The possibilities of interpretation of experimental data on the basis of the theory are also discussed.     

Explanation of the glasslike anomaly in the low-temperature specific heat of incommensurate phases

An explanation of the glasslike anomaly observed in the low-temperature specific heat of incommensurate phases is proposed. The key point of this explanation is to properly account for the phason damping when computing the thermodynamic magnitudes. The low-temperature specific heat of the incommensurate phases is discussed within three possible scenarios for the phason dynamics: no phason gap, static phason gap, and a phason gap of dynamical origin. Existing NMR and inelastic scattering data indicate that these scenarios are possible in biphenyl, blue bronze K(0.30)MoO(3), and bis (4-chlorophenyl) sulfone respectively. Estimates of the corresponding low-temperature specific heat are in reasonable agreement with the experiments.     

Precise mass measurement of a double-stranded 500 base-pair (309 kDa) polymerase chain reaction product by negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) has been used to determine the mass of a double-stranded 500 base-pair (bp) polymerase chain reaction (PCR) product with an average theoretical mass of the blunt-ended (i.e. unadenylated) species of 308 859.35 Da. The PCR product was generated from the linearized bacteriophage Lambda genome which is a double-stranded template. Utilization of ethanol precipitation in tandem with a rapid microdialysis step to purify and desalt the PCR product was crucial to obtain a precise mass measurement. The PCR product (0.8 pmol/μL) was electrosprayed from a solution containing 75% acetonitrile, 25 mM piperidine, and 25 mM imidazole and was infused at a rate of 200 nL/min. The average molecular mass and the corresponding precision were determined using the charge-states ranging from 172 to 235 net negative charges. The experimental mass and corresponding precision (reported as the 95% confidence interval of the mean) was 309 406 +/- 27 Da (87 ppm). The mass accuracy was compromised due to the fact that the PCR generates multiple products when using Taq polymerase due to the non-template directed 3'-adenylation. This results in a mixture of three PCR products with nearly identical mass (i.e. blunt-ended, mono-adenylated and di-adenylated) with unknown relative abundances that were not resolved in the spectrum. Thus, the experimental mass will be a weighted average of the three species which, under our experimental conditions, reflects a nearly equal concentration of the mono- and di-adenylated species. This report demonstrates that precise mass measurements of PCR products up to 309 kDa (500 bp) can be routinely obtained by ESI-FTICR requiring low femtomole amounts. Copyright 1999 John Wiley & Sons, Ltd.     

Scenario of the electric breakdown and UV radiation spectra in single-bubble sonoluminescence

In a preceding paper we put forward the hypothesis that the single-bubble sonoluminescence (SBSL) is caused by strong electric fields arising near the surface of a collapsing gas bubble on account of the flexoelectric effect in water. Here we argue that these fields can indeed provoke a multiple electric breakdown in water, in a micron-size region near the surface of the collapsing gas bubble, and show that the main numerical characteristics of the SBSL can be naturally explained within this mechanism. The SBSL spectra are determined by radiative transitions between high-energy levels of noble-gas atoms excited by hot electrons produced by the strong flexoelectric field in “cold” water. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 7, 428–433 (10 October 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Influence of striction on soliton interaction in crystals

Striction-mediated attraction of domain walls, solitons in incommensurate phases, and Abrikosov vortices in superconductors are considered. It is shown (a) that it is this type of attraction that can be responsible for a soliton-density jump in lock-in transitions and (b) that the strain-induced vortex interaction in superconductors with a high Ginzburg-Landau parameter is higher by one or two orders of magnitude than was assumed earlier.     

Low-frequency phonon dynamics,spin-lattice relaxation,and sound attenuation in crystals with incommensurate phases

Specific features of the low-frequency response of a phason and an amplitudon in the region of small wave vectors are considered in incommensurate displacive-type phases at high and low temperatures. The corresponding anomalies of spin-lattice relaxation (SLR) rate and attenuation of the longitudinal sound in the vicinity of the normal phase transformation into an incommensurate phase are analyzed. It is shown that the divergence of the amplitudon response at small wave vectors and low frequencies induced by the interaction with phasons clearly manifests itself only at low temperatures T and that the pronounced amplitudon contribution proportional to T³ to the SLR rate is associated with this divergence. The phason-response divergence at low temperatures leads to the frequency-independent contribution proportional to T to the SLR rate.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.