Model for the distribution of aftershock interoccurrence times

In this work the distribution of interoccurrence times between earthquakes in aftershock sequences is analyzed and a model based on a nonhomogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The analytically derived distribution of interoccurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis.     

On the depletion of235U and234U in commercially available uranium compounds: A survey using low energy γ-ray spectrometry

A survey of the situation regarding depletion of²³⁵U and²³⁴U in nine commercially available uranium compounds is reported. It was done by using a low energy -ray counting method, based on peak area ratio and dilute uranium solution. This survey shows that in Canada and USA there may be a large inventory of uranium compounds inadequately labelled regarding their isotopic composition; this situation is likely to be prevalent in many other countries.     

Landslides, forest fires, and earthquakes: examples of self-organized critical behavior

Per Bak conceived self-organized criticality as an explanation for the behavior of the sandpile model. Subsequently, many cellular automata models were found to exhibit similar behavior. Two examples are the forest-fire and slider-block models. Each of these models can be associated with a serious natural hazard: the sandpile model with landslides, the forest-fire model with actual forest fires, and the slider-block model with earthquakes. We examine the noncumulative frequency–area statistics for each natural hazard, and show that each has a robust power-law (fractal) distribution. We propose an inverse-cascade model as a general explanation for the power-law frequency–area statistics of the three cellular-automata models and their ‘associated’ natural hazards.     

States inN=79142Eu populated in the decay of142Gd

The structure of¹⁴²Eu is investigated through the beta decay of¹⁴²Gd, whose decay half-life is measured to be (69.1±1.0) s. A level scheme comprising 42 transitions depopulating 18 excited states is constructed. With the help of the deduced ft values and measured internal conversion coefficients, spin-parity assignments are proposed for several states in¹⁴²Eu. The level systematics of the doubly odd,N=79 isotones are discussed.     

Sensitivity analysis of closed-loop control systems on flexible structures

Local-velocity feedback (LVF) and linear-quadratic Gaussain (LQG) control schemes are implemented on passively tuned reaction mass actuators to control the vibrations of a flexible structure. The structure is lightly damped and possesses closely coupled low-frequency resonant modes. Both LVF and LQG controllers successfully eliminate the structure's vibrations. However, if the passive tuning parameters of the actuators are slightly mistuned, implementing LVF control actually results in an unstable system. On the other hand, LQG control proves to be insensitive to large changes in the passive tuning parameters of the actuators. In fact, the system with LQG control is never unstable, no matter what the actuator's passive tuning parameters are.     

Synthesis,Characterization, and Anticancer Activities of Pyrogallol‐Based Arylspiroborates

Arylspiroborate salts derived from pyrogallol, gallic acid, and propyl gallate have been prepared and characterized fully, including an X‐ray diffraction study for the tetrabutylammonium gallic acid complex 4 . The tetrabutylammonium salts were examined for their potential anticancer activities against renal cell carcinoma (RCC) cell lines, using NBu₄[Bcat₂] (cat = catecholato) as a control.     

Screening test of silver nanoparticles in biological samples by graphite furnace-atomic absorption spectrometry

A simple, rapid and inexpensive screening test is presented to determine the presence of silver (Ag) nanoparticles in biological samples. The method is based on graphite furnace-atomic absorption spectrometry (Zeeman background correction) where an increase in the atomization temperature is observed with an increase in the particle size of Ag. The method is able to determine the presence of Ag ions from the presence of nano-Ag of 20, 60 and 80?nm, but the methodology was less apt to resolve nanoparticles between 20 and 60?nm. The proposed methodology was capable of determining the presence of dissolved Ag(+) from 20?nm in prepared mixtures, and in the liver of rainbow trout exposed to either dissolved or 20-nm nano-Ag.     

Decay of140Gd to states inN=77140Eu

The structure of¹⁴⁰Eu has been investigated through the decay of¹⁴⁰Gd, which has a measured half-life of 16.2±0.8 s. A decay scheme is constructed, which comprises 22 transitions depopulating 16 excited states.     

A Raman study of lithium fluoride containing fast ionic conducting glasses

The role of fluorine in the structure of fluoro-borate fast ionic conducting glasses has been studied by Raman spectroscopy. It is shown that addition of LiF results in important structural changes, compared to binary glasses with the same O/B ratio. The Raman results are consistent with the participation of fluorine in the network. Careful control of the O/B ratio is required in order to detect the alkali fluoride-induced structural changes by Raman spectroscopy.