Half Orders Of Magnitude Research Articles

Determination of benzoate by paper chromatography with visualization due to its inhibitory activity in the reaction of the photosensitized autooxidation of pyrogallol A

The oxidation of 1,2,4-triacetoxybenzene (Pyrogallol A) and 3,3′,5,5′-tetramethylbenzydine by air oxygen in presence of tris-(2,2′-dipyridyl)ruthenium(II) as a photosensitizer is studied upon irradiation by visible light. The photooxidation of pyrogallol A was inhibited selectively by benzoate at pH 9–11. The rate of the reaction was not affected by other carboxylic acids but was influenced by short-chained aliphatic amines and transition metals. We developed a semiquantitative procedure for the determination of benzoate by paper chromatography. Therein, a common solution of pyrogallol A and a photosensitizer were used for the visualization followed by irradiation with an incandescent bulb. Benzoate was detected as a light spot with Rf ∼ 0.3 against a brown background. The measurement of reflectance intensity for the spot by reflectometry allowed the determination of 1 × 10−5–0.01 M benzoate within a precision of half-order of magnitude. The procedure was validated by comparison to the data of capillary electrophoresis and used to test beverages containing benzoate at levels of 10−4–10−3 M.

Impact of Pr on the properties of InP based layers for light sources and detectors

AbstractWe report the optimization of LPE growth technique for the preparation of InP and GaInAsP high quality and high purity layers by using Pr purification effect. We have found that Pr addition into the growth melt leads to the reduction of the layer defect density by a half order of magnitude and carrier concentrations diminished to 1014 cm–3. Three types of p‐n junction based radiation detection structures were prepared and their detection performance was assessed by using α‐particles emitted from the 241Am radioactive source. The type III structure, utilizing the p‐n junction with both components grown with Pr addition, exhibits the highest charge collection efficiency. Pr admixture was also exploited in the preparation of quaternary GaInAsP(Pr) active region in the double heterostructure GaInAsP/InP emitting at 1200 nm. Purification effect of Pr addition is demonstrated by measuring impurity concentrations deduced from C‐V curves and by low temperature PL spectra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Conformation, Length, and Speed Measurements of Electrodynamically Stretched DNA in Nanochannels

A method is presented to rapidly and precisely measure the conformation, length, speed, and fluorescence intensity of single DNA molecules constrained by a nanochannel. DNA molecules were driven electrophoretically from a nanoslit into a nanochannel to confine and dynamically elongate them beyond their equilibrium length for repeated detection via laser-induced fluorescence spectroscopy. A single-molecule analysis algorithm was developed to analytically model bursts of fluorescence and determine the folding conformation of each stretched molecule. This technique achieved a molecular length resolution of 114nm and an analysis time of around 20ms per molecule, which enabled the sensitive investigation of several aspects of the physical behavior of DNA in a nanochannel. λ-bacteriophage DNA was used to study the dependence of stretching on the applied device bias, the effect of conformation on speed, and the amount of DNA fragmentation in the device. A mixture of λ-bacteriophage with the fragments of its own HindIII digest, a standard DNA ladder, was sized by length as well as by fluorescence intensity, which also allowed the characterization of DNA speed in a nanochannel as a function of length over two and a half orders of magnitude.

The presence of nanostructured Al 2O 3 in PMMA-based gel electrolytes

Gel polymer electrolytes (GPEs)-based on poly(methyl methacrylate) PMMA and propylene carbonate (PC) with LiClO 4 or NaClO 4 salt are prepared using either the commercial product Superacryl ® or directly from the monomer and AIBN (2,2′-azobis(isobutyronitrile)) initiator. The nanostructured aluminum oxide is added to the mentioned systems in various ratios. Solutions of liquid PC–perchlorate and polymer electrolytes are compared with focus on ionic conductivity. The ionic conductivity of polymer-based electrolytes is significantly influenced (of almost by one half order of magnitude at room temperature) by the addition of nanosized Al 2O 3. On the contrary, the conductivity of liquid electrolytes is decreased by the addition of alumina in the blend. A slight enhancement of mechanical properties is observed.

Light sensitivity of photoconducting polymer systems with polymethine dyes based on derivatives of 2(4)-methylquinoline and indole

The photosensitivity of conducting polymer films with newly synthesized polymethine dyes is investigated. It is demonstrated that the photosensitivity of polymer films based on poly(o-hydroxyamide) with transport indole molecules forming intermolecular complexes with dyes is two or three times higher than the photosensitivity of the polymer films containing indole as a structural component of the dye. The introduction of the indole-containing dye into the photoconducting poly(vinylcarbazole) leads to an increase in the photo-conductivity by one and a half orders of magnitude. In this case, the quantum yield increases to η = 0.085. A correlation is revealed between the electronic structure of the dyes, the characteristics of the photoconduction in the materials under investigation, and the mechanisms of charge relaxation in the samples. An increase in the photoconductivity of the films results in the crossover from the drift mechanism of charge relaxation to the relaxation mechanism associated with intrinsic electrical conduction.

Activity of a PtBi alloy in the electrochemical oxidation of formic acid

Formic acid oxidation in acid solution was examined on a PtBi alloy characterized by X-ray photoelectron spectroscopy. Three chemical states of Bi, i.e., PtBi or Bi(0), Bi 2O 3 and BiO(OH) were found. Electrochemical characterization revealed that PtBi follows the behavior of its constituents, as well as that Bi is not stable in the PtBi alloy. It was established that the activity of PtBi is highly dependent of the reduction/oxidation of Bi species. Oxidation of formic acid does not occur on Bi covered PtBi. Rotated PtBi showed impressive activity relative to polycrystalline Pt, with the onset potential shifted by 0.25 V towards more negative potentials, and attained steady state current densities at 0.05 V, higher by two and half orders of magnitude. The activity of PtBi is caused by UPD phenomena of Bi on Pt, which was electrochemically detected. In addition, based on XPS analysis, it is proposed that the activity of PtBi could also be caused by the bifunctional action of hydroxylated Bi species.

Optimal choice of granularity in commonsense estimation: Why half-orders of magnitude?

It has been observed that when people make crude estimates, they feel comfortable choosing between alternatives that differ by a half-order of magnitude (e.g., were there 100, 300, or 1000 people i...

Optimal choice of granularity in commonsense estimation: Why half-orders of magnitude?

It has been observed that when people make crude estimates, they feel comfortable choosing between alternatives that differ by a half-order of magnitude (e.g., were there 100, 300, or 1000 people in the crowd?) and less comfortable making a choice on a more detailed scale, with finer granules, or on a coarser scale (like 100 or 1000). In this article, we describe two models of choosing granularity in commonsense estimates, and we show that for both models, in the optimal granularity, the next estimate is three to four times larger than the previous one. Thus, these two optimization results explain the commonsense granularity. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 843–855, 2006.

Effective demagnetization factor of quasi-single-crystal and granular YBa2Cu3O7−x thin disks

The effective demagnetization factor neff of quasi-single-crystal and granular YBa2Cu3O7−x thin disks with different values of the edge barrier height, bulk pinning, and demagnetization is measured by a Hall probe with the use of a trapped magnetic flux as a test field. As the trapped magnetic flux increases, neff reaches a maximum as a function of the external field; the qualitative behavior of this maximum is independent of the morphology of a sample. It is shown that, when the densities of intragranular and intergranular critical currents differ by about one and a half orders of magnitude, the demagnetization factor neff is mainly determined by the geometry of a sample rather than by the energy of Josephson coupling between grains. The experimental results are in agreement with the results of calculations performed within the proposed model of isolated crystallites (grains).

The applicability of power-law frequency statistics to floods

Many natural hazards satisfy power-law (fractal) frequency-size statistics to a good approximation for medium and large events. Examples include earthquakes, volcanic eruptions, asteroid impacts, landslides, and forest fires. A major question is whether this is also true for floods. A number of authors have argued in favor of the applicability of power-law statistics to floods. We discuss these arguments and consider a number of examples, using both instrumental records and paleoflood studies. In our analyses we consider both annual and partial-duration flood series. We argue that use of annual floods for statistical considerations strongly biases the flood-frequency estimates, as in some years, the annual flood will be much smaller than a number of ‘statistically independent’ floods (partial-duration floods) in other years. We examine six USGS hydrologic stations with drainage areas from 41 to 95,300 km 2, representing very different climatic regions and hydrologic conditions, and with periods of records ranging from 74 to 110 water years. Excellent power-law fits to each partial-duration series are found taking Q∼ T α , with Q the discharge associated with the recurrence interval T, and the power-law exponent α ranging from 0.27 to 0.90. We also consider paleoflood estimates for Axehandle Alcove on the Colorado River and Bonza Alcove on the Paria River, and find that that power-law extrapolations based on instrumental partial-duration series for stations in each of these two areas is within a half order of magnitude when compared to their respective paleoflood estimates. Finally, we consider an alternative approach to extreme streamflows that has been proposed, examining the cumulative probability distribution of instrumental daily mean streamflows. We show that this distribution is in good agreement with the power-law correlation found using the partial-duration series.

Structure and Ferroelectric Properties of Single Crystal PMNT Thin Films

ABSTRACT Single crystal thin films of relaxor PMNT, (1 − x)PbMg1/3Nb2/3O3–xPbTiO3, x = 0 to 0.35, were hetero-epitaxially grown on (001) SrTiO3 by a magnetron sputtering. XRD study showed the unit cell of the PMNT thin films was a c-enlongated tetragonal with highly strained structure at the film thickness below 50 nm. As the film thickness increased above a critical film thickness of around 300 nm, the PMNT thin films evolved from the tetragonal phase to the pseudo-cubic of relaxed structure. We have evaluated the dielectric properties of the relaxed single crystal PMNT thin films. The dielectric constant increased with the increase of the PT as expected: The room temperature dielectric constants at 100 kHz were 800 for PMN and 2700 for PMN-35PT. The PMN-35PT thin films, however, showed a broad temperature anomaly with low maximum dielectric constants of 4800. The d33 piezoelectric coefficients estimated were 290 pC/N which were different from bulk single crystal values by half order of magnitude, although the dielectric and piezoelectric properties of the relaxed structure were expected to be compatible to bulk materials. The low dielectric constant was not simply attributed to the stress and/or interfacial effect.

The relationship between lightning activity and surface wet bulb temperature and its variation with latitude in Australia

Convective Available Potential Energy (CAPE) is the driving force for thunderstorm development. CAPE is closely controlled by wet bulb temperature. The lightning activity measured by a network of ten lightning flash counters widely distributed across continental Australia was studied as a function of wet bulb temperature. At each of the stations, the monthly total of lightning ground flashes, N, increased sharply with the increase of the monthly mean daily maximum wet bulb temperature, Tw, max. The dependence was strongest in the tropics and became less pronounced at temperate latitudes. In Darwin (latitude 12° S), the lightning ground flash activity increased by over three orders of magnitude over a 7 °C range of Tw, max. The corresponding increases for Coffs Harbour (latitude 30° S) and for Melbourne (latitude 38° S) were about one and a half orders of magnitude and about half an order of magnitude, respectively, each over a 10 °C range of Tw, max. Power law approximations were derived for each of the ten stations and showed that the logarithm of N was directly proportional to the power, P, of Tw, max. The value of P showed a sharp exponential decrease with increasing latitude away from the equator.

Uranium emission spectra with a low power microwave plasma source

This work presents the first report of uranium spectra generated by a low power microwave plasma source to conduct emission measurements. Distinct uranium peaks in the wavelength range examined from 320 to 430 nm have been successfully obtained with a 200 W plasma utilizing low gas flow rates. The influence of temperature on the uranium behavior in the plasma source is discussed, and the intensity of the spectral lines obtained with this low power source is systematically compared with the results reported in literature, in which high power plasma sources were employed. Concentration effects are studied and the calibration curves are made for some strong spectral lines. The detection limits of uranium are also estimated to be at the 0.4 ppm level, with linear dynamic range at least two and half orders of magnitude. This research establishes a method to effectively generate uranium atoms and ions at a low power and low gas flow rate, which should be useful for uranium fundamental characteristic studies and on-site uranium monitoring work.

Development and evaluation of a method to detect and quantify enteroviruses using NASBA and internal control RNA (IC-NASBA)

We have developed a rapid, sensitive, and specific assay for the detection and quantification of enteroviruses using nucleic acid sequence-based amplification (NASBA). The inclusion of an internal control (IC) increased the precision and accuracy of the method over a standard NASBA assay and provided a way to detect assay inhibition. The assay was sensitive to 10 viral particles with amplification and detection occurring in as little as 18 min. The assay detected a variety of different enteroviruses to the exclusion of non-target viruses. The standard NASBA method resulted in predictions of viral load to within an order of magnitude of the expected number, as compared with prediction to within less than a half order of magnitude using the IC-NASBA method. Rapid and sensitive detection of enteroviruses is important in both clinical samples to diagnose illness and in environmental samples to assess risk of wastewater contamination and potential health hazards.

Preparation of p-type InP layers for detection of radiation

We have focused on the investigation of the impact of Ce, Tm, Tm 2O 3, and Lu addition in the liquid-phase epitaxial growth process on the structural and electro-optical properties of InP layers in the context of their possible application in detector structures, where detection will be mediated via the depletion layer of high quality Schottky contact. The effect of Tm 2O 3 and Lu is reported for the first time. The grown layers were examined via scanning electron microscopy, low-temperature photoluminescence spectroscopy, capacitance–voltage measurements using the mercury probe and by the temperature-dependent Hall effect. Availing Tm addition with concentration 5.4×10 −2 at%, we have prepared thick (>10 μm) p-type conductivity InP layers with the structural defect density reduced by a half-order of magnitude and reduced electrically active impurity concentration up to ∼7×10 14 cm −3. We point out that Tm appears as a promising candidate for the preparation of very pure p-type InP layers. The mechanism of purification efficiency of different rare earths from donors and acceptors leading to the n→p conductivity type crossover has been discussed.

Studies on electrical properties of La 0.8Sr 0.2Ga 0.8Mg 0.2O 2.80 (LSGM) and LSGM–SrSn 1− xFe xO 3 ( x = 0.8; 0.9) composites and their chemical reactivity

We report the electrical conductivity properties of solid-state synthesized perovskite-like La 0.8Sr 0.2Ga 0.8Mg 0.2O 2.80 (LSGM) and LSGM–SrSn 1− x Fe x O 3 ( x = 0.8; 0.9) composites. LSGM exhibits both bulk and grain-boundary contribution in the ac impedance plots. The grain-boundary conductivity ( σ gb) is slightly (≤half-order of magnitude) higher than that of the bulk oxide ion conductivity ( σ bulk). Powder XRD study reveals that no chemical reaction occurs between LSGM and SrSn 1− x Fe x O 3 (1:1 wt.%) at 1000 °C (48 h) and forms a single-phase perovskite-like compound at 1300 °C (48 h) in air, while in hydrogen atmosphere, at 800 °C for 48 h, a growth of LaSrGaO 4 and LaSrGa 3O 7 impurity phases and formation of metallic Fe was observed. The LSGM–SrSn 1− x Fe x O 3 ( x = 0.8; 0.9) composites show a single or part of semicircle in air at low-temperature regime. The electrical conductivity of the composites were found to be much higher compared to pure LSGM and lower about an order of magnitude than those of pure Sn-doped SrFeO 3 perovskite.

Ambient temperature proton conducting plastic crystal electrolytes

A non-aqueous ionic liquid based on imidazole was prepared and showed high proton conductivity. Its incorporation into the plastic crystal phase of succinonitrile at low molar proportions resulted in a solid material with high conductivity throughout the plastic crystal range and of particular interest at 25 °C (1.5 × 10 −3 S/cm). The addition of a compatible polymer have resulted in a remarkable increase in the mechanical properties but diminished the conductivity by a one-and-a half order of magnitude.

Improved Approximate Maximum-Likelihood Receiver for Differential Space–Time Block Codes Over Rayleigh-Fading Channels

In this paper, an approximate maximum-likelihood (ML) receiver for differential space-time block codes is investigated. The receiver is derived from the ML criterion and is shown to mitigate error floor occurring in a conventional differential receiver very well. Because the receiver employs knowledges of signal-to-noise ratio (SNR) and fading rate, we study mismatched cases when these parameters are not accurate. It is shown that the receiver is more sensitive to the mismatched parameters when the fading rate is high. Then, a union bound on the bit error probability is derived. The bounds show good agreement with the simulation results at high fading rate and at high SNR. Finally, a modified receiver, denoted as multistage receiver, is proposed to compensate the so-called intrablock interference caused by the time-varying characteristic of the channel within a transmission block. The multistage receiver offers further reduction of error floor of about half order of magnitude as compared with an approximate ML receiver.

Efficient Accumulation of Antiprotons and Positrons, Production of Slow Mono-Energetic Beams, and Their Applications

Recent progress of ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) project, particularly the antiproton trapping and slow antiproton production, is discussed. An RFQD (Radio Frequency Quadrupole Decelerator) installed in the ASACUSA beam line has an excellent deceleration efficiency of 25% providing 10-130keV antiprotons, which improves the final accumulation efficiency at least one and half orders of magnitude. The decelerated antiprotons are then injected in a large volume multiring trap, stored, and electron-cooled. About 1 million antiprotons are successfully accumulated per one AD shot and 10-500eV antiprotons are extracted as a mono-energetic beam. A UHV compatible positron accumulation is newly developed combining electron plasma and an ion cloud, which yields an accumulation rate as high as 400e + /s/mCi, two and a half orders of magnitude higher than other UHV compatible schemes. A new scheme to synthesize a spin-polarized antihydrogen beam is also discussed, which will play a vital role in determining the magnetic moment of antiproton with high precision.

Correlation of Pr, Dy, and Tb addition with physical properties of InP layers prepared by liquid phase epitaxy

The characterisation of thick (>10 μm) InP layers prepared by liquid phase epitaxy with Pr, Dy and Tb rare earth element (REE) addition in the growth melt for applications in radiation detector structures is reported. A significant improvement of all the studied parameters with increasing concentration of REE up to critical value (0.25 wt%) was observed. The structural defect density was reduced by one order of magnitude and the residual impurity concentration by three and a half order of magnitude (< 1015 cm–3). The conductivity has been changed from n to p-type when REE exceeded certain concentration limit in the melt (0.15 wt% for Pr, 0.05 wt% for Tb and 0.03 wt% for Dy). The low-temperature photoluminescence (PL) spectra narrowed and the corresponding fine lines were resolved. Comparison of PL peaks of n and p- type conducting layers with the obtained electrical data leads to the conclusion that the dominant acceptor impurity for the n to p-type crossover is Ge for Pr addition and Mn for Tb and Dy addition.