Investigation on luminescence of Na3Ca6(PO4)5:Eu2+ phosphor for LEDs

In this paper, a series of Na₃Ca_6(1−x)(PO₄)₅:xEu²⁺ (NCP:xEu²⁺, 0 ≤ x ≤ 4%) phosphors were prepared by conventional solid-state reaction method, and their photoluminescence properties were studied. Upon 365 nm excitation, the typical NCP:2%Eu²⁺ phosphor shows an asymmetric bluish green emission band with the dominant peak at 498 nm which could be attributed to the 4f⁶5d¹-4f⁷ transition of Eu²⁺. By measuring the time-resolved photoluminescence spectra, it reveals more than one Eu²⁺ emission center in the Eu²⁺-activated NCP phosphors. By monitoring 498 nm, the excitation spectrum of NCP:2%Eu²⁺ demonstrates a broad excitation band ranging from 240 to 450 nm, which can match well with the emission wavelength of the NUV LED chip. The SEM image shows that the average particle size of NCP:2%Eu²⁺ is about 19.4 µm. The above results imply that the NCP:Eu²⁺ phosphor could have potential application in LEDs.     

Production of singlet oxygen by Ru(dpp(SO3)2)3 incorporated in polyacrylamide PEBBLES

Polyacrylamide (PAA) and amine-functionalized PAA (AFPAA) nanoparticles with disulfonated 4,7-diphenyl-1,10-phenantroline ruthenium (Ru(dpp(SO₃)₂)₃) have been prepared. The nanoparticles produced have a hydrodynamic radius of 20–25 nm.

The amount of singlet oxygen (¹O₂) produced by Ru(dpp(SO₃)₂)₃ as been measured using anthracene-9,10-dipropionic acid (ADPA). A kinetic model for the disappearance of ADPA, by steady state irradiation of Ru(dpp(SO₃)₂)₃ at 465 nm, has been developed taking also into account a consumption not mediated by ¹O₂. This direct consumption of ADPA is evaluated by irradiating in the presence of NaN₃ and is about 30% of the total. All the experimental results are very well described by the model developed, both for free Ru(dpp(SO₃)₂)₃ and with this dye incorporated in the nanoparticles.

It is found that the polyacrylamide matrix does not quench the ¹O₂ produced, allowing it to reach the external solution of the nanoparticles and react with ADPA. When the matrix possesses amine groups, AFPAA, the amount of ¹O₂ that reacts with ADPA is slightly reduced, 60%, but most of the ¹O₂ produced can still leave the particles and react with external molecules. The particles produced may therefore be used as sources of ¹O₂ in photodynamic therapy (PTD) of cancers. The fact that those nanoparticles do not quench significantly the ¹O₂ makes possible the future development of ¹O₂ sensors based on PAA nanoparticles with the appropriate sensor molecule enclosed.     

Water activities, osmotic and activity coefficients of the system (NH4)2SO4–K2SO4–H2O at the temperature 298.15 K

The mixed aqueous electrolyte system consisting of ammonium and potassium sulfates has been studied using the hygrometric method at the temperature 298.15 K. The water activities are measured at total ionic strength values ranging from 0.60 to 8.25 mol kg⁻¹ for different ionic strength fractions (y) of (NH₄)₂SO₄ with y=0.20, 0.50 and 0.80. The obtained data allow the deduction of osmotic coefficients. The experimental results are compared with the predictions of the Zdanovskii–Stokes–Robinson (ZSR), Kusik and Meissner (KM), Robinson and Stokes (RS), Lietzke and Stoughton (LS II), Reilly–Wood and Robinson (RWR) and Pitzer models. From these measurements, the new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture.     

应用微机理论研究Ni（pz）4Cl2型络合物的光,热,磁性质

利用ｄ＾８（Ｄ４ｈ＊）全组态统一晶场理论模型，研究了Ｎｉ（ｐｚ）４Ｃｌ２型化合物能量矩阵的特征值、特征矢以及计算其ＺＦＳ、ＥＰＲ参量的计算方法，并利用该方法拟合出了Ｎｉ（ｐｚ）４Ｃｌ２型化合物的光谱、ＺＦＳ和ＥＰＲ参量，总结出利用微机对其拟合的一般规律，计算结果与实验值一致。     

Multivalued (S)+ operators and generalized variational inequalities

In this paper, we derive some new existence results for the generalized variational inequalities by introducing multivalued (S)¹₊ operators. Applications to nonlinear inequalities and the generalized complementarity problem are given.     

Solubility prediction for the nonelectrolyte urea–hydrogen peroxide–water system and thermodynamic solubility product calculation for CO(NH2)2 ⋅ H2O2 using the modified Pitzer model

The Pitzer interaction model, which has been applied successfully to the thermodynamic simulation of electrolyte solutions and electrolyte–nonelectrolyte solutions, was extended to nonelectrolyte–nonelectrolyte solution system. In the present work, the modified Pitzer model was used for calculation and correlation of the ternary CO(NH₂)₂–H₂O₂–H₂O system at 283.15 K. The value of the Pitzer interaction parameters for the ternary system and the thermodynamic solubility product of CO(NH₂)₂⋅H₂O₂ were determined using a least-square optimization procedure with coupling activity coefficient and solubility data. The predicted isothermal solubilities agree well with the result obtained from the experiment. The results indicated that the modified Pitzer model could be successfully used to predict the component solubility of the nonelectrolyte–nonelectrolyte system.     

On ?∞, robust stability and performance with ?2 and ?∞ perturbations

In this paper we will consider systems with linear time-invariant perturbations. We will analyze robust performance in the ?₂ and ?_∞ settings. The ?₂ setting gives rise to the familiar case of structured singular values, and a stability criterion is given by the “small μ” theorem. We show that although the necessary and sufficient criterion of robust stability for the ?_∞ case (?_∞ stability with structured ?_∞-gain bounded perturbations) is the same “small μ” criterion, a system with ?₂-gain bounded perturbations is never ?_∞ stable.     

Sprayed CdIn2O4 thin films for liquefied petroleum gas (LPG) detection

Nanocrystalline cadmium indium oxide (CdIn₂O₄) thin films of different thicknesses were deposited by chemical spray pyrolysis technique and utilized as a liquefied petroleum gas (LPG) sensors. These CdIn₂O₄ films were characterized for their structural and morphological properties by means of X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The dependence of the LPG response on the operating temperature, LPG concentration and CdIn₂O₄ film thickness were investigated. The results showed that the phase structure and the LPG sensing properties changes with the different thicknesses. The maximum LPG response of 46% at the operation temperature of 673 K was achieved for the CdIn₂O₄ film of thickness of 695 nm. The CdIn₂O₄ thin films exhibited good response and rapid response/recovery characteristics to LPG.     

Connections between minimum entropy control and mixed 2/ ∞ control for time-varying systems

In this paper two properties of minimum entropy control for linear time-varying systems are investigated. An entropy formulation for anti-causal systems is first considered. Minimizing the norm of an anticausal system is straightforward because of the fact that the norm of an operator is equal to the norm of its adjoint. This is not true for the entropy measure. For this reason a separate formula for the entropy of anti-causal systems is needed in order to consider dual problems that arise in optimal control theory. Secondly, we investigate the relationship between the entropy measure for time-varying systems and the ₂ and _∞ norms. For time-invariant systems, minimum entropy control has been shown to be a good mixed ₂/ _∞ controller. In this paper we show that this is also true in the time-varying case.     

Tetrakis(alkylthio)-substituted lutetium bisphthalocyanines for sensing NO2 and O3

In this study, the nitrogen dioxide (NO₂) and ozone (O₃) sensing properties of a series bis[tetrakis(alkylthio) phthalocyaninato] lutetium(III) complexes [(C_nH_2n+1S)₄Pc]₂Lu(III) (n = 6, 10, 16) are investigated as a function of concentration in the temperature range between 25 °C and 150 °C. The concentration ranges were 1–10 ppm for NO₂, and 50 ppb–1 ppm for O₃. The response time and the sensor response to NO₂ are measured for approximately 1 min and 100% ppm⁻¹, respectively, for compound 1 at room temperature. At room temperature, all compounds are in the solid phase. The response time decreases to a few seconds with increasing operation temperature to 150 °C. At this temperature, all compounds are in the liquid crystal phase. The fastest response to oxidizing gases is observed at the liquid crystal phase of the Pcs. It has also been observed that the response time and the sensor response depend on the alkyl chain lengths of the Pcs. The doping effect of oxygen has been determined under high purity nitrogen N₂ flow, after exposure to dry air, at a different period of time and after annealing. It has been found that the conductivities of [(C_nH_2n+1S)₄Pc]₂Lu(III) thin films increased after exposure to dry air and the conduction mechanism also changed from ohmic behavior to space-charge-limited conduction.     

Red phosphor Li2Mg2(WO4)3: Eu3+ with lyonsite structure for near ultraviolet light-emitting diodes

A series of Eu³⁺-activated Li₂Mg₂(WO₄)₃ (LMW) materials were synthesized by high temperature solid state reactions. The phosphor can be effectively excited by 394 nm near ultraviolet light and emit intense red light with high color purity. Prepared phosphors can be indexed to LMW with particular lyonsite structure. The occupation of Eu³⁺ in LMW is selective. Most of Eu³⁺ comes into ¹A sites without inversion symmetry. The present research suggests that LMW is a suitable host for luminescence applications and Eu³⁺-activated LMW is a promising phosphor for phosphor-converted white light-emitting diodes.     

Structural, optical and electrical properties of CdO/Cd(OH)2 thin films grown by the SILAR method

Successive Ionic Layer Adsorption and Reaction (SILAR) was used to form Cd(OH)₂ thin films from aqueous cadmium–ammonia complex on glass substrates at room temperature and the thermal annealing effect on thin films was studied. The as-deposited films were annealed at 200, 300 and 400 °C for 1 h in an oxygen atmosphere for conversion from Cd(OH)₂ to CdO and change in the structural, optical and electrical properties of the films and the effect of the light on the electrical properties of the films were investigated. The structural and surface morphological properties of the films were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that Cd(OH)₂ phase is converted into the cubic CdO films by annealing. The band gap energy values of films decreased from 3.59 to 2.13 eV through increasing annealing temperature. It was found that the current increased with increasing light intensity and CdO films were more conductive than the as-deposited films.     

Minimum ℓ1, ℓ2, and ℓ∞ Norm Approximate Solutions to an Overdetermined System of Linear Equations

Cadzow, J. A., Minimum ℓ₁, ℓ₂, and ℓ_∞ Norm Approximate Solutions to an Overdetermined System of Linear Equations, Digital Signal Processing12 (2002) 524–560Many practical problems encountered in digital signal processing and other quantitative oriented disciplines entail finding a best approximate solution to an overdetermined system of linear equations. Invariably, the least squares error approximate solution (i.e., minimum ℓ₂ norm) is chosen for this task due primarily to the existence of a convenient closed expression for its determination. It should be noted, however, that in many applications a minimum ℓ₁ or ℓ_∞ norm approximate solution is preferable. For example, in cases where the data being analyzed contain a few data outliers a minimum ℓ₁ approximate solution is preferable since it tends to ignore bad data points. In other applications one may wish to determine an approximate solution whose largest error magnitude is the smallest possible (i.e., a minimum ℓ_∞ norm approximate solution). Unfortunately, there do not exist convenient closed form expressions for either the minimum ℓ₁ or the minimum ℓ_∞ norm approximate solution and one must resort to nonlinear programming methods for their determination. Effective algorithms for determining these two solutions are herein presented (see Cadzow, J. A., Data Analysis and Signal Processing: Theory and Applications).     

聚硫堇和磁性核／壳纳米粒子CoFe2O4／SiO2修饰电极对多巴胺的测定

制备了聚硫堇（PTh）-磁性核,壳纳米粒子CoFe2O4／SiO2修饰电极。研究了神经递质多巴胺（DA）在该修饰电极上的电化学行为。实验表明,PTh—CoFe2O4／SiO2复合膜修饰电极对DA的电催化作用优于PTh修饰电极。在pH7．5的PBS中,DA在该修饰电极上的CV曲线于-0．16V和-0．22V处出现一对灵敏的氧化还原峰,峰电流显著增加。差分脉冲伏安法（DPV）氧化峰电流ips与DA浓度在1．2×10^-7-3．6×10^-5mol／L范围内呈良好的线性关系,线性回归方程ips（μA）=5．307c（μmol／L）＋0．7891,r=0．9923,检出限为6．0×10^-8mol／L（S／N=3）。常见物质对DA的检测无干扰,DA注射液样品检测结果与中国药典2010版（二部）规定方法一致。     

Gas sensitivity of Zn doped α-Fe2O3(SO4, Sn, Zn) to carbon monoxide

It is shown that the doping of Zn and Sn can improve the gas sensitivity of α-Fe₂O₃-based sensing material to CO. X-ray photo-electron spectroscopy analysis suggests that this is mainly due to the fact that the simultaneous doping of Zn and Sn can increase the S and hence SO₄²⁻ contents in the α-Fe₂O₃(SO₄²⁻, Sn, Zn) sensing material. The results also suggest that under a given condition, the gas sensitivity of α-Fe₂O₃(SO₄²⁻, Sn, Zn) to CO can be optimised by properly adjusting the doped Zn content.     

Equilibrium between MB2 (M=Ti,Zr,Hf) UHTC and Ni: A thermodynamic database for the B-Hf-Ni-Ti-Zr system

MB₂ (M=Ti,Zr,Hf) Ultra High Temperature Ceramics (UHTCs) are characterised by melting temperatures in excess of 3000 °C and have structural, physical, transport, and thermodynamic properties suitable for use as thermal barriers in extreme environments. It is then necessary to investigate interactions of the diborides with the materials they are supposed to protect. To this end it has been developed a CALPHAD thermodynamic database for the calculation of phase equilibria and thermodynamic properties in the quinary system B-Ni-Ti-Zr-Hf. The database contains thermodynamic parameters for all the phases included in the 10 binary and 10 ternary sub-systems of B-Ni-Ti-Zr-Hf. A few binary systems (B-Hf, B-Ti, B-Zr, Hf-Ni, Ni-Zr) have been slightly modified with respect to the previous assessments and several ternary systems (B-Hf-Ni, B-Ni-Ti, B-Ni-Zr, B-Hf-Zr, B-Ti-Zr, Hf-Ni-Ti, Hf-Ni-Zr, Hf-Ti-Zr, Ni-Ti-Zr) have been completely assessed or re-assessed in this work with particular attention to the self-consistency of the models adopted.     

Worst-case identification in ℓ2: linear and nonlinear algorithms

We consider worst-case identification in the ℓ₂ norm. Given an unknown system h ε ℓ₁ one wishes to choose bounded inputs u ε ℓ∞ such that given finitely many corrupted output measurements {y(k): 0 ≤ k}of Y = h*u + η, where η is noise, assumed small, one can construct an approximation g with g - h₂ → 0 as η∞ → 0 and n → ∞. It is shown that inputs can be chosen such that to identify a sequence of length n with an ℓ₂ error of O(η∞) one requires only O(n) measurements. A numerical example is inclu