Applying MORT to the analysis of the “Tláhuac” incident

The “Tláhuac” incident occurred in Mexico City on 23 November 2004. The fatal incident took place when an angry crowd burnt two police officers alive and seriously injured another after mistaking them for child kidnappers. The third policeman who was finally rescued by colleagues suffered serious injuries. This paper presents some preliminary results of the incident by applying the management over-sight risk tree (MORT) technique. The MORT technique may be regarded as a structured checklist in the form of a complex “fault tree” model that is intended to ensure that all aspects of an organization's management are looked into when assessing the possible causes of an incident. Some other approaches such as a systemic view will be adopted in the future for further analysis. It is hoped that by conducting such analysis lessons can be learnt so that incidents such as the case of “Tláhuac” can be prevented in the future.     

Effect of the properties of the water sorbent on the heat generation in the Fe-C-NaCl-H<Subscript>2</Subscript>O-O<Subscript>2</Subscript> system

The water adsorption and retention behaviors of vermiculite, silica gel, activated carbon, and a zeolite are analyzed in relation to their pore structures, and their effects on the dynamics of heat generation in Fe-C-NaCl-H₂O-O₂-water sorbent systems are investigated.     

Studies of the Local Structure and the g Factors of the Cu<Superscript>2+</Superscript> Site in Y<Subscript>2</Subscript>BaCuO<Subscript>5</Subscript>

The local structure and the g factors (g _x , g _y , and g _z ) of the Cu²⁺ site in Y₂BaCuO₅ are theoretically studied using the perturbation formulas of the g factors for a 3d⁹ ion in orthorhombically elongated octahedra. The orthorhombic field parameters in these formulas are determined from the superposition model and the local geometry of the system. From the calculations, the oxygen octahedron is found to undergo the local elongation ΔZ (≈0.05 Å) along c-axis and the relative bond length variation ΔX (≈0.1 Å) along a- and b-axes, respectively. The calculated g factors based on the above local structure are in good agreement with the experimental data. The relationships between the anisotropies of the g factors and the low symmetrical (orthorhombic) distortions of the Cu²⁺ site in Y₂BaCuO₅ are discussed.     

From the History of Science to the History of Knowledge – and Back

The history of science can be better understood against the background of a history of knowledge comprising not only theoretical but also intuitive and practical knowledge. This widening of scope necessitates a more concise definition of the concept of knowledge, relating its cognitive to its material and social dimensions. The history of knowledge comprises the history of institutions in which knowledge is produced and transmitted. This is an essential but hitherto neglected aspect of cultural evolution. Taking this aspect into account one is led to the concept of extended evolution, which integrates the perspectives of niche construction and complex regulative networks. The paper illustrates this concept using four examples: the emergence of language, the Neolithic revolution, the invention of writing and the origin of mechanics.     

Going much beyond the Durfee square: enhancing the <Emphasis Type="Italic">h</Emphasis><Subscript>T</Subscript> index

The objective of this research is to develop a new patent bibliometric performance measure by using modified citation rate analyses with dynamic backward citation windows. Cited half-life employed in bibliometrics was adopted in order to establish a model of annual patent backward citation windows. Based on the dynamic behavior of backward citation windows, the annual backward patent citation rates for each technology domain can be calculated to measure its bibliometric performance. It was found that the dynamic backward citation window represents more accurately the citation cycle time which is a key factor on technology assessment. Because different technology domain may have disparate attributes, a normalized backward citation rate was developed to measure the corresponding rank for each domain respect to the entire industry. Three technology domains were then chosen for demonstrative case studies which represent semiconductor, LCD, and drug industries.     

An Approximation for the Entropy Measuring in the General Structure of<i>SGSP</i>₃

In this article, we calculate various topological invariants such as symmetric division degree index, redefined Zagreb index, VL index, first and second exponential Zagreb index, first and second multiplicative exponential Zagreb indices, symmetric division degree entropy, redefined Zagreb entropy, VL entropy, first and second exponential Zagreb entropies, multiplicative exponential Zagreb entropy. We take the chemical compound named Proanthocyanidins, which is a very useful polyphenol in human’s diet. They are very beneficial for one’s health. These chemical compounds are extracted from grape seeds. They are tremendously anti-inflammatory. A subdivision form of this compound is presented in this article. The compound named subdivided grape seed Proanthocyanidins is abbreviated as SGSP₃. This network SGSP₃, is converted and modeled into its mathematical graphical formation with the support of the latest mathematical tools. We have also developed many closed formulas for the measurement of entropy for the general chemical structure of the subdivided grape seed Proanthocyanidins network. The achieved outcomes can be correlated with the chemical version of SGSP₃ to get a better understanding of its biological as well as physical features.     

Two-Dimensional Nanogranularity of the Oxygen Chains in the YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>6.33</Subscript> Superconductor

The organization of dopants in high-temperature superconductors provides complex topological geometries that control superconducting properties. This makes the study of dopants’ spatial distribution of fundamental importance. The mobile oxygen ions, y, in the CuO₂ plane of YBa₂Cu₃O_{6 + y} (0.33 < y < 0.67) form ordered chains which greatly affect the transport properties of the material. Here, we visualize and characterize the two-dimensional spatial organization of these oxygen chains using scanning micro X-ray diffraction measurements in transmission mode on a thin single-crystal slab with y = 0.33 (T _c = 7 K) near the critical doping for the insulator-to-metal transition. We show the typical landscape of percolation made of a granular spatial pattern due the oxygen chains segregating in quasi-one-dimensional needles of ortho-II (O-II) phase embedded in an insulating matrix with low density of disordered oxygen interstitials.     

Effect of the precipitation sequence on phase formation in the ZrO<Subscript>2</Subscript>-CeO<Subscript>2</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> system

We have studied phase formation processes during heat treatment of precipitates in the ZrO₂-Al₂O₃ and ZrO₂-CeO₂-Al₂O₃ systems. During heat treatment of powders prepared by coprecipitation of precursors to ZrO₂, CeO₂, and Al₂O₃, α-Al₂O₃ is formed at higher temperatures, which is due to the formation and decomposition of T-ZrO₂ and metastable Al₂O₃ phases. The precipitation sequence in the ZrO₂-CeO₂-Al₂O₃ system influences the lattice parameters of the forming T-ZrO₂-based solid solutions because of the different degrees of Ce⁴⁺ and Al³⁺ substitutions for Zr⁴⁺.     

Modeling of the electrical properties of the mixed ionic-electronic conductor BiMg<Subscript>0.25</Subscript>Cu<Subscript>0.75</Subscript>NbO<Subscript>5</Subscript>

A physically justified equivalent circuit of an ionic-electronic conductor has been proposed which accounts for the unusual electrical behavior of BiMg_0.25Cu_0.75NbO₅. The problem of separating the electronic and ionic contributions to its conductance has been resolved by analyzing the frequency dependences of its impedance. A new approach has been proposed for interpreting the temperature dependences of capacitance and conductance for this material.     

Optimization of the Carbosilicothermic Synthesis of the Ti<Subscript>4</Subscript>SiC<Subscript>3</Subscript> MAX Phase

We have studied the formation of the Ti4SiC3 MAX phase during the vacuum carbosilicothermic reduction of TiO₂ with a combined reducing agent consisting of SiC and elemental Si and analyzed the effects of the synthesis temperature, heat treatment time, and percentage of elemental silicon in the starting mixture on the Ti₄SiC₃ yield. Optimal Ti₄SiC₃ synthesis conditions are as follows: temperature from 1550 to 1650°C, isothermal holding time of 360 min, and the starting-mixture composition TiO₂ + 1.2SiC + 0.6Si. The Ti₄SiC₃ yield then reaches 92 wt %.     

Nucleation of the Plasticity at Nanodeformation of the Y<Subscript>3</Subscript>Al<Subscript>5</Subscript>O<Subscript>12</Subscript> Yttrium-Aluminum Garnet

The nanoindentation in the continuous stiffness measurement (CSM) mode was used to study the nucleation of the plasticity at the nanodeformation of the yttrium-aluminium garnet (YAG) having a low ((111) YAG single crystal after the annealing at the temperature of 1300°C) and a high (polycrystalline yttrium-aluminium garnet with a grain size of ~ 20 μm after the mechanical polishing) density of dislocations. For a sample having a high dislocations density a smooth elastoplastic transition was observed in the nanocontact as a result of the motion and multiplication of dislocations that are already present in the sample. For (111) YAG single crystal after annealing at the temperature of 1300°C an abrupt elastoplastic transition (pop-in) caused by a homogeneous nucleation of dislocations in the region under the contact was observed.     

Influence of the concentration of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> on the electrical properties of SnO<Subscript>2</Subscript> varistors

Varistors are electronic materials with nonohmic behavior. In traditional SnO₂ varistors, CoO acts as a densifying agent, Nb₂O₅ increases the electrical conductivity of SnO₂ grains, and Cr₂O₃ produces a more uniform microstructure and acts as an oxygen retaining agent at the grain boundaries. The present work involved a systematic study of the substitution of Nb₂O₅ for Sb₂O₃ in the composition of a ternary varistor system. The compositions were prepared by conventional wet ceramic processing using deionized water, and the resulting slips were dried by spray-drying. Pellets were produced under a pressure of 330 MPa and sintered at 1,350 °C for 2 h. Similar to the behavior of Nb₂O₅, increasing the concentration of Sb₂O₃ reduced the nonlinear behavior of the ceramic and its breakdown electric field while increasing its leakage current. The samples’ microstructure showed greater porosity, suggesting that higher concentrations of Sb₂O₃ reduce the sintering rate, probably in response to the higher concentration of tin vacancies in the structure.     

Correlation between the physical properties and the novel applications of Mg<Subscript>0.7</Subscript>Cu<Subscript>0.3</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> nano-ferrites

Nano-ferrite of the general formula Mg_0.7Cu_0.3Fe₂O₄ was prepared by citrate-gel auto combustion method. The structure was studied by X-ray diffraction, Brunauer–Emmet–Teller, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. The crystallite size of the investigated nano ferrite was ?39 nm. The magnetic hysteresis measurements at different temperatures (100, 170, 240, and 300 K) were performed using a vibrating sample magnetometer. A correlation between magnetic behavior and lattice strain has been established. Arrott plot has been employed to understand the magnetic behavior of nano-crystalline Mg_0.7Cu_0.3Fe₂O₄. The magnetic susceptibility was carried out using Faraday’s method. Magnetic constants such as Curie temperature, effective magnetic moment, saturation magnetization, and coercivity were obtained and reported. Based on UV diffuse reflectance spectroscopy studies, the optical band gaps are in the range from (1.3–1.9 eV), hence the investigated samples could act as visible light driven photo catalysts.     

Effect of dispersion and polymeric coatings on the magnetic properties of the Fe<Subscript>73.1</Subscript>Cu<Subscript>1.0</Subscript>Nb<Subscript>3.0</Subscript>Si<Subscript>15.5</Subscript>B<Subscript>7.4</Subscript> amorphous alloy

We tested Fe_73.1Cu_1.0Nb_3.0Si_15.5B_7.4 amorphous alloy for changes in the magnetic properties accompanying the transition from the strip form into a powder and after modification with polymeric coatings. It is shown that the dispersion down to particles smaller than 10 μm in size and the procedure of modification do not, in fact, worsen the magnetic properties of the alloy.     

Specific features of the processes of thermal desorption and HDDR in the Zr<Subscript>3</Subscript>FeO<Subscript>x</Subscript>H<Subscript>y</Subscript> system

We study the processes of thermal desorption of hydrogen and hydride disproportionation for the Zr₃FeO_x (x = 0–1.0 ) intermetallic compounds depending on the amount of oxygen. As the oxygen content of the Zr₃FeO_x compounds increases, their susceptibility to disproportionation at room temperature decreases. It is shown that, for the Zr₃FeO_x compounds, the character of thermal desorption of hydrogen in a vacuum and the character of disproportionation in hydrogen at high temperatures strongly depend on the oxygen content. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 5, pp. 81–84, September–October, 2007.     

Effect of impurities on the electrical properties of the defect perovskite Li<Subscript>0.33</Subscript>La<Subscript>0.57</Subscript>TiO<Subscript>3</Subscript>

A perovskite phase with the composition Li_0.33La_0.57TiO₃ modified with up to 7 wt % Bi₂O₃, SiO₂, Li₃PO₄, or Li₃BO₃ has been prepared by solid-state reactions. The samples in the LLTO–Li₃PO₄, LLTO–Bi₂O₃, and LLTO–SiO₂ systems were single-phase over the entire composition range studied. In the LLTO–Li₃BO₃ system, increasing the lithium borate concentration causes a transition from a defect perovskite structure to the layered perovskite-related structure of Li₂La₂Ti₃O₁₀. The addition of Bi₂O₃ and Li₃PO₄ has been shown to increase the total conductivity of the ceramics by almost one order of magnitude. Li₃BO₃, Li₃PO₄, Bi₂O₃, and SiO₂ additives improve the sintering behavior of the Li_0.33La_0.57TiO₃ ceramics.