Fluorene Based Ferric Complex as Colorimetric and Fluorometric Probe for Highly Selective Detection of CN− and S2− Anions

Journal of Fluorescence - A series of new chemosensor molecules bearing benzothiazole-, quinoline- and phthalazine-functionalized fluorene derivatives were synthesized and their complexation...     

Fluorescein Based Three-channel Probe for the Selective and Sensitive Detection of CO32− Ions in an Aqueous Environment and Real Water Samples

Journal of Fluorescence - We have constructed a novel fluorescein-based fluorescent chemosensor, FL-In, functionalised with an indole moiety and capable of sensing by both the optical...     

Luminescence of Eu3+ Ions in a Matrix of a Fluorinated Yttrium–Aluminum Composition

Physics of the Solid State - We studied the optical spectra of fluorinated yttrium–aluminum compositions activated by Eu3+ ions. The compositions were synthesized by thermal decomposition at...     

Highly Selective Recognition on Enatioselective of R(+) and S(−)-1,1-Bi(2-Naphthol) Using of Eu(dap)<Subscript>3</Subscript> Complex as Photo Probe

The chiral recognition phenomenon was observed in enantioselective and excited-state energy transfer processes. Based on bimolecular luminescence quenching kinetics for a system containing chiral molecules, the quenching efficiency was evaluated by Stern-Volmer equation for a system containing a chiral R(+) and S(−) resolved quencher species. The utility of this methodology is confirmed by examining the enantio-selective excited-state quenching between Eu(dpa)₃ complex (where dpa = pyridine-2,6-dicarboxylate) acting as the energy donor to R(+)-1,1-Bi(2-Naphthol) and S(−)-1,1-Bi(2-naphthol) as the energy acceptor was studied in solution. The results of this study confirm the utility of luminescence measurements as a probe of chiral discriminatory behavior.     

Structural Changes in Human Serum Albumin According to the Data on the Phosphorescence Kinetics of a Luminescent Probe — Eosin

The influence of the human serum albumin (HSA) denaturation by a surface-active substance (sodium dodecyl sulfate (SDS)) on the phosphorescence of a luminescent probe (eosin) has been investigated. The dependences of the eosin-phosphorescence intensity on the SDS concentration were determined at different pH levels of an HSA solution. It has been shown that at SDS concentrations lower than the critical concentration necessary for micelle formation, the hydrophobic interactions of eosin with the protein influence the deactivation of the eosin triplet states. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 660–663, September–October, 2005.     

Chemiluminescence Determination of Sodium New Houttuyfonate in Pharmaceutical Preparations Based on Tween 80—Rhodamine B System

Strong chemiluminescence (CL) emission was observed when sodium new houttuyfonate (SNH) was mixed with Tween 80 in sulfuric acid medium in the presence of rhodamine B. Base on this phenomenon, a sensitive flow injection-CL method for the determination of SNH was developed. Under the optimum conditions, the CL emission is linearly with SNH concentration in the range 8.0–4000 ng mL⁻¹, with a detection limit of 2.7 ng mL⁻¹ (3σ). As a preliminary application, the proposed method was successfully applied to the determination of SNH in pharmaceutical preparations. The possible CL mechanism was also discussed in this paper.     

Indication of the Expression of Transgene in Rice Plant Based on Hyperspectral Remote Sensing Technique Ⅱ——Growth Monitoring of Samples in the Contrast Experiment

Since the complication of monitoring and evaluating the problems about the transgenic expression and its impacts on the receptor in the transgenic crop breeding and other relevant evaluated works, the authors in the present work tried to assess the differences of spectral parameters of the transgenic rice in contrast with its parent group quantitatively and qualitatively, fulfilling the growth monitoring of the transgenic samples. The spectral parameters (spectral morphological characteristics and indices) chosen are highly related to internal or external stresses to the receipts, and thus could be applied as indicators of biophysical or biochemical processes changes of plant. By ASD portable field spectroradiometer with high-density probe, fine foliar spectra of 8 groups were obtained. By analyzing spectral angle and continuum removal, the spectral morphological differences and their locations of sample spectra were found which could be as auxiliary priori knowledge for quantitative analysis. By investigating spectral indices of the samples, the quantitative differences of spectra were revealed about foliar chlorophyll a+b and carotenoid content. In this study both the spectral differences between transgenic and parent groups and among transgenic groups were investigated. The results show that hyperspectral technique is promising and a helpful auxiliary tool in the study of monitoring the transgenic crop and other relevant researches. By this technique, quantitative and qualitative results of sample spectra could be provided as prior knowledge, as certain orientation, for laboratory professional advanced transgenic breeding study.     

The power and limits of the Judd—Ofelt theory: a case of Pr3+ and Tm3+ acetates and dipicolinates

Electronic absorption spectra of crystals and solutions of praseodymium and thulium acetates and dipicolinates are reported. The influence of spectral properties of both ligands on intensities of the f—f transitions in the crystals studied is discussed. In the near-IR region, overtone vibrations of ligands are strongly coupled with the f—f transitions, particularly with the hypersensitive ones. In the UV spectral range, absorption bands of the π → π?, n → π? and possible charge transfer of metal ? ligand transitions affect f—f transitions and should also be taken into account. The phenomenological Judd—Ofelt parameters evaluated for praseodymium complexes in solution and crystals are meaningless, because no set of intensities unbiased by ligand transitions and/or neighbouring f-d configurations is available. For Tm³⁺ compounds the Judd-Ofelt analysis has given quite good results, however no significant influence of the metal ion environment changes on the Ωλ parameters can be observed.     

Features of the Pulsed Magnetization Switching in a High-Coercivity Material Based on ε-Fe2O3 Nanoparticles

Physics of the Solid State - The magnetic structure of the ε-Fe2O3 iron oxide polymorphic modification is collinear ferrimagnetic in the range from room temperature to ~150 K. As the...     

Evaluation of Enhancement Effects as a Function of the Molarity of Gd-Based Contrast Media at 3.0 and 1.5 T: Based on the T1 Effective Pulse Sequence Parameter

The purpose of this study was to evaluate the alterations of diluted molarity of contrast media to emit the maximum signal intensity by changing the parameters of pulse sequences. The phantom was developed by diluting the magnetic resonance imaging (MRI) T1 contrast medium. The phantom images were obtained by 1.5 and 3.0 T MRI systems. We conducted Pearson’s analysis to reveal the correlation of the signal-to-noise ratio (SNR)_90%, the change of the concentration range of the contrast media which shows over 90% SNR, with changing the parameters of T1 effect pulse sequences in both 1.5 and 3.0 T imaging. As the flip angle increased, the SNR increased for all contrast media in magnetization-prepared rapid gradient echo and two-dimensional fast low angle shot pulse sequences at 1.5 and 3.0 T. Although the SNR increased until 30°, the SNR was almost the same over 30° in volumetric interpolated breath-hold examination at 1.5 and 3.0 T. The minimum contrast molarity of the representing SNR_90% was decreased according to the increasing time to repeat in spin echo. The present study revealed that the high concentration technique of contrast media on three pulse sequences (VIBE, MPRAGE, and 2D FLASH) could be useful to obtain images with better SNR.     

Change in the Absorption Spectra of Membranes Containing Co(III)‐ and Sn(IV) Tetraphenyl Porphyrins as a Result of the Use of Anion‐Selective Electrodes Based on Them

Electronic absorption spectra of the components of the membranes of anionselective electrodes containing Co(OH) and Sn(OH) Sn(OH)₂ tetraphenyl porphyrins (TPP) as electroactive substances and various softeners and lipophilic ionic additives have been investigated. 2Nitrophenyloctylic ether, bromonaphthalene, dibutyl phthalate, and dioctyl phthalate were used as softeners; tetradecyl ammonium nitrate and tetrakis(4chlorophenyl)potassium borate were used as ionic additives. To investigate the electronic absorption spectra, we dissolved the membranes in cyclohexane at different pH before and after their use. The influence of the acidity and the nature of a softener on the position and intensity of the absorption bands of metalloporphyrin in a membrane is discussed. It is shown that the use of membranes containing Co(OH)TPP in highly acidic media is accompanied by its demetallation and the formation of protonized forms of TPP. The membranes based on Sn(OH)₂TPP are more stable in acid media.     

A-site and B-site substitutions and the emission properties of Eu3+ ions in ABO3 –type cubic perovskite: A case study of BaZrO3

The emission properties of the rare earth (RE) elements have been found to be sensitive to the local lattice environment around them, and could be employed for probing the local lattice environment. Because each constituent ion of a material should have its own particular structural environment, the emission profiles in RE elements depend strongly on the doping sites of RE elements inside the host crystals. We investigated the emission properties of the Eu³⁺ ion doped BaZrO₃ (BaZrO₃:Eu) with doping site dependence (A-site vs. B-site), as well as ambient dependence in the post-annealing process. The site-selective doping was identified from the Rietveld refinement analysis on the XRD patterns of our BaZrO₃:Eu samples. Photoluminescence and photoluminescence excitation measurements showed that the emission properties of the samples with the Eu³⁺ ions substituted at Zr sites revealed much greater emission properties than those at the Ba sites. This behavior was found to accord with the change in intensity ratio of ⁵D₀ → ⁷F_0,2 to ⁵D₀ → ⁷F₁ in Eu ions, which should be a measure of the local lattice asymmetry around the Eu ions. We also found that with post-annealing in H₂ atmosphere, the emission intensities of the Eu ions increased significantly, while with post-annealing in O₂ atmosphere, they were suppressed. Our findings indicated that the cation/oxygen vacancies could change the local lattice environment around the Eu ions, as well as the valence states of Eu ions, depending on the doping site in the cubic perovskite.     

High Quantum Efficiency of Nd3+ Ions in a Phosphate Glass System using the Judd–Ofelt Theory

The optical properties of trivalent neodymium embedded in a P₂O₅–Al₂O₃–Na₂O–K₂O phosphate glass system, synthesized by the fusion method, are studied. Absorption, luminescence, lifetime, and Raman spectroscopy measurements were performed and the Judd–Ofelt theory was applied to determine optical parameters such as the quantum efficiency and the stimulated emission cross section of the Nd³⁺-doped glass system. This structure has high quantum efficiency at low Nd³⁺ concentrations, comparable to the efficiency of a commercial YAG:Nd³⁺ crystal. We discuss the mechanisms responsible for the high quantum efficiency observed in the proposed phosphate glass system.     

Growth and Form in Biology： Generation of the Plant Morphology by Spontaneous Symmetry Breaking Based on a Pressure Field

Considering the role of mechanical forces playing in the morphogenetic pattern formation, we propose a secondorder differential equation for the growth and form of plants based on the turgot pressure field at the organ and cellular level. The solutions can well describe various kinds of morphological features of flowers under certain hypotheses. The plant morphology is considered as the spontaneous symmetry breaking of a circular growing boundary, while the employed hypotheses are subjected to further experimental confirmation.     

Construction of a Turn-off–on Fluorescent System Based On Aggregation Induced Emission of Acetaldehyde Using Carbonized Polymer dots and Tb3+

Journal of Fluorescence - It was the first time to report the aggregation induced emission (AIE) of acetaldehyde (AA) on the surface of carbonized polymer dots (CPDs) with the auxiliary of Tb3+....     

Determination of Trace Mercury by Solid Substrate-Room Temperature Phosphorimetry Quenching Method Based on Catalytic Effect of Hg2+on Formation of the Ion Association Complex [Sn(XO)6]4+·[(Fin)4]

A new method for the determination of trace mercury by solid substrate-room temperature phosphorimetry (SS-RTP) quenching method has been established. In glycine-HCl buffer solution, xylenol orange (XO) can react with Sn⁴⁺ to form the complex [Sn(XO)₆]⁴⁺. [Sn(XO)₆]⁴⁺ can interact with Fin⁻ (fluorescein anion) to form the ion associate [Sn(XO)₆]⁴⁺·[(Fin)₄]⁻, which can emit strong and stable room temperature phosphorescence (RTP) on polyamide membrane (PAM). Hg²⁺ can catalyze H₂O₂ oxidizing the ion association complex [Sn(XO)₆]⁴⁺·[(Fin)₄]⁻, which causes the RTP to quench. The ΔIp value is directly proportional to the concentration of Hg²⁺ in the range of 0.016–1.6 fg spot⁻¹ (corresponding concentration: 0.040–4.0 pg ml⁻¹, 0.40 μl spot⁻¹), and the regression equation of working cure is ΔIp=10.03+83.15 m Hg²⁺ (fg spot⁻¹), (r=0.9987, n=6) and the detection limit (LD) is 3.6 ag spot⁻¹(corresponding concentration: 9.0×10^–15 g ml⁻¹, the sample volume: 0.4 μl). This simple, rapid, accurate method is of high selectivity and good repeatability, and it has been successfully applied to the determination of trace mercury in real samples. The reaction mechanism for catalyzing H₂O₂ oxidizing the ion association complex ([Sn(XO)₆]⁴⁺·[(Fin)₄]⁻) SS-RTP quenching method to determine trace mercury is also discussed.     

Theoretical studies of the dependence of EPR g-factors on local structure for the trigonal Er3+–VK centres in KMgF3 and KZnF3

The dependence of the EPR g-factors on the local structural parameter for a 4f¹¹ configuration ion Er³⁺ in a trigonal crystal-field has been studied by diagonalizing the 364×364 complete energy matrices. Our studies indicate that the EPR spectra of the trigonal Er³⁺–V_K centers in KMgF₃ and KZnF₃ may be attributed to the translation of the cubic Kramers doublet Γ₇. Furthermore, the EPR g-factors of the trigonal Er³⁺–V_K centers may be interpreted reasonably by the shifts ΔZ≈0.340 Å and ΔZ≈0.303 Å of the Er³⁺ ions toward the charge compensator V_K along the C₃ axis for the KMgF₃:Er³⁺ and the KZnF₃:Er³⁺ systems respectively.     

Electromagnetic Form Factors of Λ Hyperon in the Vector Meson Dominance Model and a Possible Explanation of the Near-Threshold Enhancement of the e+e-→ Λ(Λ) Reaction

The near-threshold e+e-→ Λ(Λ) reaction is studied with the assumption that the production mechanism is due to a near-Λ(Λ)-threshold bound state.The cross sectio...     

Effects of heat treatment and TiO2 content on the optical properties of Eu3+ doped TiO2–SiO2 thin films

The photoluminescence properties of Eu³⁺-doped TiO₂–SiO₂ thin films were investigated. The films were deposited on silicon substrates by the sol–gel process using the dip-coating method. The molar ratio of TiO₂ content was varied from 25% to 100%, while Europium concentration was fixed to 1%. The obtained films were calcinated at various temperatures ranging from 400 °C to 1300 °C, which allowed determining the optimal conditions for the Eu³⁺ luminescence. Meanwhile, the structure of TiO₂–SiO₂ powders, prepared in the same conditions as the films, was also studied by Raman spectroscopy. It revealed the role of Europium and SiO₂ on the stabilization of the anatase phase and the importance of the silica matrix in the control of titania particle size.