Electro- and Heat Transfer in $$\mathbf{Cd}_{\mathbf{0.22}}\mathbf{\hbox {Hg}}_{\mathbf{0.78}}{} \mathbf{Te}$$ Single Crystals in the Temperature Range of Their Practical Applications

The thermal and electrical conductivity of a single-crystal \(\hbox {Cd}_{0.22}\hbox {Hg}_{0.78}\hbox {Te}\) was studied in the temperature range of practical applications (77–300 K). The sample has impurity conductivity, which is limited by the scattering of charge carriers by phonons. Heat in the sample is transferred by phonons and thermal conductivity is limited by phonon–phonon scattering. The electron contribution to the thermal conductivity can be neglected.     

Role of reactive species in the photocatalytic degradation of amaranth by highly active N-doped $$\mathbf{WO}_{\mathbf{3}}$$

A novel, highly visible light active N-doped \(\hbox {WO}_{3}\) (\(\hbox {N}\)-\(\hbox {WO}_{3})\) is successfully synthesized via thermal decomposition of peroxotungstic acid–urea complex. The photocatalytic activity of \(\hbox {N}\)-\(\hbox {WO}_{3}\) is evaluated for the degradation of amaranth (AM) dye under visible and UVA light along with the role of reactive species, which has not yet been studied for \(\hbox {N}\)-\(\hbox {WO}_{3}\) photocatalysts. Doping of N into substitutional and interstitial sites of \(\hbox {WO}_{3}\) is confirmed by X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy. At a pH of 7, 1 g \(\hbox {l}^{-1}\) of \(\hbox {N}\)-\(\hbox {WO}_{3}\) can completely degrade \(10\,\hbox {mg } \hbox {l}^{-1}\) of AM within 1 h under visible and UVA light. For the degradation of AM by \(\hbox {N}\)-\(\hbox {WO}_{3}\) under visible and UVA light, \(\hbox {h}^{+}\) is found to be the main reactive species, while \(\cdot \hbox {OH}\) contributes to a lesser extent. On the contrary, \(^{1}\hbox {O}_{2}, \cdot \hbox {O}_{2}^{-}\) and \(\hbox {e}^{-}\) show negligible roles. The crucial role of \(\hbox {h}^{+}\) indicates effective suppression of electron–hole recombination after N doping. Dye sensitization and oxidation by reactive species are found to be the major pathway for the degradation of AM under visible and UVA light, respectively.     

Differentiation Between {\varvec{Staphylococcus\,aureus}} and {\varvec{Staphylococcus\,epidermidis}} Using Microcalorimetry

Microcalorimetry is a highly sensitive experimental technique that determines heat changes in any process or transformation. All organisms produce heat due to their metabolism. The rate of heat flow is an adequate measure of metabolic activity of living beings and their component parts. Microorganisms produce small amounts of heat: 1 pW to 3 pW per cell. Although the heat produced by bacteria is very small, their exponential reproduction in a culture medium permits heat detection through microcalorimetry. A microcalorimetric growth and metabolic study was carried out for the bacteria Staphylococcus aureus and Staphylococcus epidermidis, by using heat liberated during metabolism. A thermal conductivity calorimeter of the Calvet type was used. The inside of the calorimeter contains two stainless steel cells (experimental and reference) with a screw-on Teflon cap with a hole in the center. Experiments were carried out with final concentrations of the order of $(10^{6}, 10^{5}, 10^{3}$ ( 10 6 , 10 5 , 10 3 , and 10) CFU $\,{\cdot }\,\text{ ml }^{-1}$ · ml ? 1 . These were kept at a constant temperature of 309.65 K. The plot of change in heat voltage versus time enables acquisition of the characteristic growth curve for each bacterial strain. Thermograms were analyzed mathematically and helped determine the characteristic parameters for each microorganism, and led to the identification of the bacterial species.     

Three-dimensional mixed mode I+II+III singular stress field at the front of a {\varvec{(}}\mathbf{111 }{\varvec{)}[}\bar{\mathbf{1 }}\bar{\mathbf{1 }}\mathbf 2 {\varvec{]}\times [}\mathbf 1 \bar{\mathbf{1 }}\mathbf 0 {\varvec{]}} crack weakening a diamond cubic mono-crystalline plate with crack turning and step/ridge formation

A heretofore-unavailable mixed Frobenius type series, in terms of affine-transformed x-y coordinate variables of the Eshelby–Stroh type, is introduced to develop a new eigenfunction expansion technique. This is used, in conjunction with separation of the z-variable, to derive three-dimensional mixed-mode I+II+III asymptotic displacement and stress fields in the vicinity of the front of a semi-infinite through-thickness $(111)[\bar{{1}}\bar{{1}}2]\times [1\bar{{1}}0]$ crack weakening an infinite diamond cubic mono-crystalline plate. Crack-face boundary conditions and those that are prescribed on the top and bottom (free, fixed or lubricated) surfaces of the diamond cubic mono-crystalline plate are exactly satisfied. Explicit expressions for the mixed mode I+II+III singular stresses in the vicinity of the front of the through-thickness crack, are presented. Most important mixed modes I+II+III response is elicited even though the far-field loading is only mode I or II or III or any combination thereof. Finally, atomistic modeling of cracks requires consideration of both the long range elastic interactions and the short range physico-chemical reactions, such as bond breaking. The Griffith-Irwin approach does not take the latter into account, and nano-structural details such as bond orientation must be accounted for. A new mixed-mode I+II+III crack deflection criterion elucidates the formation of steps and/or triangular ridges on the crack path. The planes of a multiply deflected crack are normal to the directions of broken bonds. Additionally, the mixed-mode (I+II+III) crack deflection and ridge formation are found to be strongly correlated with the elastic stiffness constants, ${c}^{\prime }_{14}$ and ${c}^{\prime }_{56}$ , of the diamond cubic single crystal concerned.     

Structural,Electrical and Magnetic Behaviour of FeTe0.5Se0.5 Superconductor

We report the synthesis as well as structural and physical properties of the bulk polycrystalline FeTe and FeTe_0.5Se_0.5 compounds. These samples are synthesised by the solid state-reaction method via vacuum encapsulation. Both studied compounds are crystallized in a tetragonal phase with space group P4/nmm. The parent FeTe compound shows an anomaly in resistivity measurement at around 78 K, which is due to the structural change along with a magnetic phase transition. The superconductivity in the FeTe_0.5Se_0.5 sample at 13 K is confirmed by the resistivity measurements. DC magnetisation along with an isothermal (M–H) loop shows that FeTe_0.5Se_0.5 possesses bulk superconductivity. The upper critical field is estimated through resistivity ρ (T,H) measurements using Gingzburg–Landau (GL) theory and is above 50 T with 50 % resistivity drop criterion. The origin of the resistive transition broadening under magnetic field is investigated by thermally activated flux flow. The magnetic field dependence of the activation energy of the flux motion is discussed.     

Thermoelectric properties of porous n-type {\text{Fe}}_{{\text{0}}{\text{.94}}} {\text{Co}}_{{\text{0}}{\text{.06}}} {\text{Si}}_{\text{2}} compounds prepared by pressureless sintering

The effects of bulk porosity on the thermoelectric properties of porous n-type ${\text{Fe}}_{{\text{0}}{\text{.94}}} {\text{Co}}_{{\text{0}}{\text{.06}}} {\text{Si}}_{\text{2}} $ compounds prepared by pressureless sintering were examined. A small amount of metallic phase ?-FeSi remained after annealing at 800 °C for 100 h. As the sintering temperature increased from 1150 to 1175 °C, the phase transition to β-FeSi₂ during annealing occurred more rapidly. The porous specimen, sintered at 1150 °C for 2 h with coarse powders (<45 μm) and then annealed at 800 °C for 100 h, showed the highest Seebeck coefficient of $ - 363_{\mu } {VK}^{ - {1}} $ at 400 °C and the highest power factor of ${\text{1}}{\text{.57}} \times 10^{ - 3} {\text{Wm}}^{ - 1} {\text{K}}^{ - 2} $ at 400 °C.     

The trace spectra of polynomial bases for $${\mathbb{F}}_{2^{n}}$$

In this paper we study the trace spectra of polynomial bases for over . Shparlinski showed that there exists a polynomial basis having O(log n) elements of trace one. Here we show that for every t ≤ n, there exists a polynomial basis having t + O(log n) elements of trace one. We also study consequences of our results to the existence of irreducible polynomials of certain weights.     

Ion exchange synthesis and thermal characteristics of some \left[ \rm{\mathbf{N}}_{{2222}}^{{+}} \right] based ionic liquids

Eight salts were obtained by reacting tetraethylammonium cation $\big[ {{\rm {\bf N}}_{{\rm {\bf 2222}}}^{{+}} } \big]$ with inorganic anions like BF $_{{4}}^{{-}}$ , NO $_{{3}}^{{-}}$ , NO $_{{2}}^{{{-}}}$ , SCN^???, BrO $_{{3}}^{{-}}$ , IO $_{{3}}^{{-}}$ , PF $_{{6}}^{{-}}$ and HCO $_{{3}}^{{-}}$ using ion exchange method. These ionic liquids (ILs) were characterized using thermal methods, infrared spectroscopy and densitometry. Thermophysical properties such as density, coefficient of volume expansion, heat of fusion, heat capacity and thermal energy storage capacity were determined. Thermal conductivity of the samples was determined both in solid and liquid phases. Owing to high values of thermal energy storage capacity coupled with handsome liquid phase thermal conductivity, ILs under investigation were recommended as materials for thermal energy storage (TES) as well as heat transfer applications.     

Exploring Magnetic Behaviour in La0.70Pr0.30Mn0.8Co0.2O3 Perovskite

Journal of Superconductivity and Novel Magnetism - This work aims to understand the magnetic behaviour in the La0.70Pr0.30Mn0.8Co0.2O3 perovskite sample. The sample was prepared by a solid-state...     

{\alpha^{\prime}}_{\text{H}} -Dicalcium silicate bone cement doped with tricalcium phosphate: characterization,bioactivity and biocompatibility

The influence of phosphorus doping on the properties of $ \alpha^{\prime}_{\text{H}} $ -dicalcium silicate (C₂S) bone cement was analyzed, in addition to bioactivity and biocompatibility. All the cements were composed of a solid solution of TCP in C₂S ( $ \alpha^{\prime}_{\text{H}} $ -C₂S_ss) as the only phase present. The compressive strength ranged from 3.8–16.3 MPa. Final setting times ranged from 10 to 50 min and were lower for cements with lower L/P content. Calcium silicate hydrate was the principal phase formed during the hydration process of the cements. The cement exhibited a moderate degradation and could induce carbonated hydroxyapatite formation on its surface and into the pores. The cell attachment test showed that the $ \alpha^{\prime}_{\text{H}} $ -Ca₂SiO₄ solid solution supported human adipose stem cells adhesion and spreading, and the cells established close contacts with the cement after 24 h of culture. The novel $ \alpha^{\prime}_{\text{H}} $ -C₂S_ss cements might be suitable for potential applications in the biomedical field, preferentially as materials for bone/dental repair.     

Low Magnetic Field Magnetocaloric Effect in $\text {Gd}_{\mathrm {5-}_{x}}$EuxGe4

The magnetocaloric effect is investigated for \(\text {Gd}_{\mathrm {5-}_{x}}\)Eu _x Ge₄ (0.25 ≤ x ≤ 2) system near a phase transition from a ferromagnetic to a paramagnetic state as a function of temperature with low external magnetic field change of 100 Oe. The sample with x = 1 has the smallest value of maximum magnetic entropy change and the specific heat change, and highest values of full-width at half-maximum and relative cooling power. The results indicate that the \(\text {Gd}_{\mathrm {5-}_{x}}\)Eu _x Ge₄ system has a prospective application for magnetic refrigerant in an extended high temperature range. Consequently, \(\text {Gd}_{\mathrm {5-}_{x}}\)Eu _x Ge₄ compounds are very attractive candidates for magnetic refrigeration applications, especially nitrogen liquefier.     

Magnetic Enhancement and Suppression of Haldane Gap in Nanocrystals of Spin-Chain $${{\hbox {Y}}_{2}}{{\hbox {BaNiO}}_{5}}$$

Nanometer scale is introduced in the well-known Haldane system \(\hbox {Y}_{2}\hbox {BaNiO}_{5}\,(S=1)\). Magnetization and pulsed-field electron spin resonance (ESR) measurements were performed. As a result, the magnetization of nanoparticles is much enhanced as compared with that of the bulk material. The Haldane gap in the bulk form tends to be suppressed as the grain size is reduced down to the nanometer scale. The chain-end \(S\hbox {-}1/2\) spins have an important contribution to the magnetism of nanoparticles. The high-field ESR data demonstrated a paramagnetic-like resonance. The frequency–field (f–H) relationship is linear and passes through the origin. The g value is about 2.16, in good agreement with the typical value of paramagnetic \(\hbox {Ni}^{2+}\). It is concluded that the nanometer scale is a new degree of freedom for controlling the ground state of quantum magnets.     

${\mathbb{Z}}$ 上框架小波包的构造方案及算法实现（英）

为了进一步推动小波理论的应用,近些年来在离散数据环境中开始了对框架小波（也称为framelets）和框架小波包的研究工作．在$\ell^2(Z)$中构造$J$-级框架小波包的方法已经由鲁大勇和易华给出．然而,如何去使用这类小波包的细节却没有给出．为了进一步丰富由鲁和易提出的$J$-级框架小波包理论体系,该文给出了快速的分解和重构算法,运用该算法可以建立不同尺度层之间小波框架系数的关系．另外,为了方便该类框架小波包的应用,文中给出了$\ell^2(Z)$中一些实用框架小波包的具体数据．文中最后通过一个数值实验展示了该类框架小波包的完美重构性质．     

Structural,elastic, optoelectronic and magnetic properties of $$\mathbf{CdHo }_\mathbf{2}{} \mathbf{S}_\mathbf{4}$$ spinel: a first-principle study

We report the results of the full-potential linearized augmented plane wave (FP-LAPW) calculations on the structural, elastic, optoelectronic and magnetic properties of \(\hbox {CdHo}_{2}\hbox {S}_{4}\) spinel. Both the generalized gradient approximation (GGA) and Trans-Blaha modified Becke-Johnson potential (TB-mBJ) are used to model the exchange-correlation effects. The computed lattice parameter, internal coordinate and bulk modulus are in good agreement with the existing experimental data. According to the calculated elastic moduli, \(\hbox {CdHo}_{2}\hbox {S}_{4}\) is mechanically stable with a ductile nature and a noticeable elastic anisotropy. The ferromagnetic phase of \(\hbox {CdHo}_{2}\hbox {S}_{4}\) is energetically favourable compared to non-magnetic one, with a high magnetic moment of about 8.15 \(\upmu _{\mathrm{B}}\). The calculated band structure demonstrates that the title compound is a direct band gap semiconductor. The TB-mBJ yields a band gap of \(\sim \)1.86 and \(\sim \)2.17 eV for the minority and majority spins, respectively. The calculated optical spectra reveal a strong response in the energy range between the visible light and the extreme UV regions.     

Characterization of $${\hbox {BaTiO}_{3}}$$ piezoelectric perovskite material for multilayer actuators

In this study, we present the results of the manufacturing of \(\hbox {BaTiO}_{3}\) powder, which is meant for use in stacked-disk multilayer actuator production. The solid-state technique was used for powder preparation. The properties of barium titanate material, at each stage of its fabrication (powder, granulate, sintered material), influencing on its application for the stacked-disk multilayer actuator were determined. Particularly, the four parameters of \(\hbox {BaTiO}_{3}\) sinter affecting on the usability properties of actuators, not found before in the literature, were estimated. Parameters characterizing the extent of material sintering, SEM microstructures and electric properties of the fabricated pellets are presented and discussed. The dilatometric curve was executed using the high temperature dilatometer to determine at which temperature barium titanate pellets and beams should be sintered to receive full dense sinters. Parameters characterizing the extent of material sintering: the apparent density, the apparent porosity and the water absorbability were estimated. Finally, the problem of metal layer deposition on barium titanate ceramics during actuator fabrication is considered.