Motorcyclists’ speed and “looked-but-failed-to-see” accidents

Previous research on motorcycle crashes has shown the frequency and severity of accidents in which a non-priority road user failed to give way to an approaching motorcyclist without seeing him/her, even though the road user had looked in the approaching motorcycle's direction and the motorcycle was visible. These accidents are usually called “looked-but-failed-to-see” (LBFS) accidents. This article deals with the effects that the motorcyclist's speed has in these accidents. It is based on the in-depth study and precise kinematic reconstruction of 44 accident cases involving a motorcyclist and another road user, all occurring in intersections. The results show that, in urban environments, the initial speeds of motorcyclists involved in “looked-but-failed-to-see” accidents are significantly higher than in other accidents at intersections. In rural environments, the difference in speed between LBFS accidents and other accidents is not significant, but further investigations would be necessary to draw any conclusions. These results suggest that speed management, through road design or by other means, could contribute to preventing “looked-but-failed-to-see” motorcycle accidents, at least in urban environments.     

Synthesis and growth of TlInSe<Subscript>2</Subscript> and TlGaSe<Subscript>2</Subscript> single crystals

Methods of synthesis and growth of TlGaSe₂ and TlInSe₂ single crystals are developed. It is shown that the Bridgman-Stockbarger technique is efficient for growth of large TlGaSe₂ single crystals, and zone recrystallization is efficient in the case of TlInSe₂.     

Synthesis and High-Temperature Heat Capacity of Dy<Subscript>2</Subscript>Ge<Subscript>2</Subscript>O<Subscript>7</Subscript> and Ho<Subscript>2</Subscript>Ge<Subscript>2</Subscript>O<Subscript>7</Subscript>

The Dy₂Ge₂O₇ and Ho₂Ge₂O₇ pyrogermanates have been prepared by solid-state reactions in several sequential firing steps in the temperature range 1237–1473 K using stoichiometric mixtures of Dy₂O₃ (or Ho₂O₃) and GeO₂. The heat capacity of the synthesized germanates has been determined as a function of temperature by differential scanning calorimetry in the range 350–1000 K. The experimentally determined C _p (T) curves of the dysprosium and holmium germanates have no anomalies and are well represented by the Maier–Kelley equation. The experimental C _p (T) data have been used to evaluate the thermodynamic functions of the Dy₂Ge₂O₇ and Ho₂Ge₂O₇ pyrogermanates: enthalpy increment H°(T)–H°(350 K), entropy change S°(T)–S°(350 K), and reduced Gibbs energy Ф°(T).     

Synthesis and High-Temperature Heat Capacity of Sm<Subscript>2</Subscript>Ge<Subscript>2</Subscript>O<Subscript>7</Subscript> and Eu<Subscript>2</Subscript>Ge<Subscript>2</Subscript>O<Subscript>7</Subscript>

The Sm₂Ge₂O₇ and Eu₂Ge₂O₇ germanates have been prepared by solid-state reactions via multistep firing of stoichiometric mixtures of Sm₂O₃ (Eu₂O₃) and GeO₂ in air at temperatures from 1273 to 1473 K. The molar heat capacity of the samarium and europium germanates has been determined by differential scanning calorimetry in the range 350–1000 K and the C _p (T) data have been used to evaluate their thermodynamic properties.     

Preparation and characterization of Co<Subscript>9</Subscript>S<Subscript>8</Subscript> nanocrystalline and nanorods

Hexagonal Co₉S₈ nanocrystal and nanorods were synthesized using cobalt chloride (CoCl₂·6H₂O), dimethyl sulfoxide (DMSO) and non-aqueous alcohol as the starting materials, and taking dimethyl sulfoxide as both sulfur source and strong infiltrator in nanorods preparation. The Co₉S₈ samples were characterized by X-ray diffraction (XRD), scanning tunneling microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and laser Raman spectrometer. The results show that the as-prepared Co₉S₈ nanocrystal with a size of 6 nm take on weak paramagnetism at room temperature. The lengths and diameters of the nanorods were about 4 μm and 200 nm, respectively. The reason for the relative lower synthesis temperature of nanorods was discussed and a ‘micro-autoclave reactor’ model was suggested as well.     

Phase transition and electrical properties of gallium- and indium-doped Bi<Subscript>10</Subscript>Ti<Subscript>3</Subscript>W<Subscript>3</Subscript>O<Subscript>30</Subscript>

Polycrystalline samples of gallium- and indium-doped Bi₁₀Ti₃W₃O₃₀ (mixed-layer Aurivillius phase with the Ti⁴⁺ and W⁶⁺ distributed at random over the perovskite-like slabs) have been prepared by solid-state reactions, and their polymorphism and electrical properties have been studied. Doping with both In³⁺ and Ga³⁺ yields limited solid solutions and shifts the ferroelectric phase transition to lower temperatures. The heterovalent substitutions of In³⁺ and Ga³⁺ for Ti⁴⁺ and W⁶⁺ increase the oxygen vacancy concentration and, accordingly, the conductivity of the material relative to the undoped compound.     

Optical and X-ray photoelectron spectroscopy of PbGeO<Subscript>3</Subscript> and Pb<Subscript>5</Subscript>Ge<Subscript>3</Subscript>O<Subscript>11</Subscript> single crystals

Pb₅Ge₃O₁₁ crystals are found to exhibit pale yellow colouration while PbGeO₃ are colourless. X-ray photoelectron spectroscopy (XPS) measurements show lead deficiency in both the crystals. The results also reveal a stronger ionic character for PbGeO₃ as compared to Pb₅Ge₃O₁₁ crystal. The binding energy of Ge3d core level in the case of Pb₅Ge₃O₁₁ crystal is found to be smaller than the binding energy of germanium oxide, thereby indicating the incomplete oxidation of Ge ions in the crystal lattice. On gamma ray irradiation, the transmission of both the crystals is observed to deteriorate uniformly over the entire wavelength range, which has been attributed to the oxidation of some of the lattice Pb ions. On gamma irradiation the changes observed in O1s core level energies for both the crystals are seen to be consistent with the changes noted in the Pb4f _7/2 and Ge3d spectra. Interestingly, the results reveal oxidation of surface Ge atoms with atmospheric oxygen under gamma irradiation.     

Thermodynamic properties and homogeneity regions of Tl<Subscript>6</Subscript>SCl<Subscript>4</Subscript> and Tl<Subscript>5</Subscript>Se<Subscript>2</Subscript>Cl

In this activity system Tl-Tl₂X-X (X = S, Se)are studied using emf measurements of concentration chains relative thallic electrode. The solid phase diagrams of these systems are clarified, homogeneity areas of the compounds Tl₆SCl₄ and Tl₅Se₂Cl are determined. On the basis of emf measurement results, relative partial molar functions of thallium in alloys and standard integral thermodynamic functions (ΔG ⁰(298 K), ΔH ⁰ (298 K), ΔS ⁰ (298 K)) of the ternary compounds Tl₆SCl₄ and Tl₅Se₂ Cl and phases of variable composition based on the latter are calculated.     

Synthesis and high-temperature heat capacity of Yb<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> and Lu<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript>

Yb₂Sn₂O₇ and Lu₂Sn₂O₇ have been prepared by solid-state reactions, by firing mixtures of Yb₂O₃ or Lu₂O₃ and SnO₂ at 1473 K, and the molar heat capacity of these compounds (pyrochlore structure) has been determined by differential scanning calorimetry. The C _p (T) data have been used to evaluate the thermodynamic properties of the stannates: enthalpy increment, entropy change, and reduced Gibbs energy.     

High-temperature heat capacity and thermodynamic properties of TbBiGeO<Subscript>5</Subscript> and DyBiGeO<Subscript>5</Subscript>

Polycrystalline TbBiGeO₅ and DyBiGeO₅ samples have been prepared by solid-state reactions, by firing stoichiometric mixtures of Tb₂O₃ (Dy₂O₃), Bi₂O₃, and GeO₂ in air at 1003, 1073, 1123, 1143, 1173, and 1223 K. The molar heat capacity of the bismuth terbium and bismuth dysprosium germanates has been determined by differential scanning calorimetry. The experimental C _p (T) data obtained in the range 350–1000 K have been used to evaluate the thermodynamic functions of the synthesized oxide compounds: enthalpy increment, entropy change, and reduced Gibbs energy.     

Synthesis,structure, and thermal expansion of M<Subscript>2</Subscript>Fe<Subscript>2</Subscript>Ti<Subscript>6</Subscript>O<Subscript>16</Subscript> and MFeTiO<Subscript>4</Subscript> compounds

Compounds that crystallize in four structure types in M₂O-Fe₂O₃-TiO₂ systems have been prepared by solid-state reactions. The M₂Fe₂Ti₆O₁₆ (M = Rb, Cs) compounds have been prepared for the first time. The thermal expansion coefficients of the MFeTiO₄ (M = Li, Na) and M₂Fe₂Ti₆O₁₆ (M = Na, K, Rb, Cs) compounds have been determined by high-temperature X-ray diffraction.     

Photoconductivity and luminescence anisotropy in ZnIn<Subscript>2</Subscript>S<Subscript>4</Subscript> and ZnIn<Subscript>2</Subscript>S<Subscript>4</Subscript>:Cu<Superscript>2+</Superscript> single crystals

ZnIn₂S₄ and ZnIn₂S₄:Cu²⁺ single crystals are shown to exhibit considerable photoconductivity and luminescence anisotropy. The mechanism of carrier recombination in the crystals is polarization-dependent. Their spectra can be understood in terms of optical transitions involving donor and acceptor levels. The degree and spectral distribution of the anisotropy can be tuned via doping and alternating growth of the three- and one-layer polytypes.     

Synthesis and thermoluminescence properties of CdB<Subscript>4</Subscript>O<Subscript>7</Subscript>:Tb<Superscript>3+</Superscript> and CdB<Subscript>4</Subscript>O<Subscript>7</Subscript>:Mn<Superscript>2+</Superscript>

Polycrystalline samples of undoped, terbium-doped (CdB₄O₇:Tb³⁺), and manganese-doped (CdB₄O₇:Mn²⁺) cadmium tetraborate have been prepared by solid-state reactions at 850°C. Using differential scanning calorimetry and X-ray diffraction, we have determined the melting point of CdB₄O₇ (t _m = 976°C) and shown that this compound melts incongruently. The observed monotonic decrease in the orthorhombic cell parameters of the doped materials indicates the formation of substitutional solid solutions (sp. gr. Pbca). The thermoluminescence intensity of the doped materials has been shown to depend on the nature and concentration of the activators and the irradiation time.     

Formation of superhard phases in the C<Subscript>diam</Subscript>-AlB<Subscript>12</Subscript> and C<Subscript>diam</Subscript>-AlB<Subscript>2</Subscript> systems at high pressures and temperatures

A chemical interaction of diamond and aluminum borides to form ternary compounds in the diamond-diamond intergranular spaces has been considered.     

Thermochemical and luminescent properties of RbVO<Subscript>3</Subscript>, CsVO<Subscript>3</Subscript>, and Rb<Subscript>0.5</Subscript>Cs<Subscript>0.5</Subscript>VO<Subscript>3</Subscript>

RbVO₃, CsVO₃, and Rb_0.5Cs_0.5VO₃ have been synthesized by the Pechini process. The vanadates have an orthorhombic structure (sp. gr. Pbcm), melt congruently in the range 650–530°C, and undergo a reversible phase transition in the range 520–340°C. We have determined the onset temperatures and end points of the transformations at a temperature scan rate of 3°C/min and their enthalpies, and measured the photo-, roentgeno-, and cathodoluminescence and diffuse reflectance spectra of the vanadates. The luminescence spectra each are well fitted with three pseudo-Voigt functions. CsVO₃ has the highest integrated emission intensity. The emission intensity of the Rb_0.5Cs_0.5VO₃ solid solution is lower than that of the simple vanadates because of the optical absorption around its intrinsic luminescence band. This may be due to the presence of stable vacancy-type structural defects in Rb_0.5Cs_0.5VO₃.     

The comparison: photoluminescence and afterglow behavior in CaSnO<Subscript>3</Subscript>:Dy<Superscript>3+</Superscript> and Ca<Subscript>2</Subscript>SnO<Subscript>4</Subscript>:Dy<Superscript>3+</Superscript> phosphors

This paper reports the comparison of photoluminescence and afterglow behavior of Dy³⁺ in CaSnO₃ and Ca₂SnO₄ phosphors. The samples containing CaSnO₃ and Ca₂SnO₄ were prepared via solid-state reaction. The properties have been characterized and analyzed by utilizing X-ray diffraction (XRD), photoluminescence spectroscope (PLS), X-ray photoelectron spectroscopy (XPS), afterglow spectroscopy (AS) and thermal luminescence spectroscope (TLS). The emission spectra revealed that CaSnO₃:Dy³⁺ and Ca₂SnO₄:Dy³⁺ phosphors showed different photoluminescence. The Ca₂SnO₄:Dy³⁺ phosphor showed a typical ⁴F_9/2 to ⁶H_j energy transition of Dy³⁺ ions, with three significant emissions centering around 482, 572 and 670 nm. However, the CaSnO₃:Dy³⁺ phosphor revealed a broad T₁ → S₀ transitions of Sn²⁺ ions. The XPS demonstrate the existence of Sn²⁺ ions in CaSnO₃ phosphor caused by the doping of Dy³⁺ ions. Both the CaSnO₃:Dy³⁺ and Ca₂SnO₄:Dy³⁺ phosphors showed a typical triple-exponential afterglow when the UV source switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO₃:Dy³⁺ and Ca₂SnO₄:Dy³⁺ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the calcium stannate host with rare-earth ions (Dy³⁺).     

High-Temperature Heat Capacity and Thermodynamic Properties of HoBiGeO<Subscript>5</Subscript> and ErBiGeO<Subscript>5</Subscript>

Polycrystalline HoBiGeO₅ and ErBiGeO₅ samples have been prepared by solid-state reactions, by firing stoichiometric mixtures of Ho₂O₃ (Er₂O₃), Bi₂O₃, and GeO₂. The effect of temperature on the heat capacity of the synthesized compounds has been investigated by differential scanning calorimetry in the range 350–1000 K. The experimental C_p(T) data have been used to evaluate the thermodynamic functions of bismuth holmium and bismuth erbium germanates: enthalpy increment, entropy change, and reduced Gibbs energy.