Chaotic Teaching-Learning-Based Optimization with Lévy Flight for Global Numerical Optimization.

Recently, teaching-learning-based optimization (TLBO), as one of the emerging nature-inspired heuristic algorithms, has attracted increasing attention. In order to enhance its convergence rate and prevent it from getting stuck in local optima, a novel metaheuristic has been developed in this paper, where particular characteristics of the chaos mechanism and Lévy flight are introduced to the basic framework of TLBO. The new algorithm is tested on several large-scale nonlinear benchmark functions with different characteristics and compared with other methods. Experimental results show that the proposed algorithm outperforms other algorithms and achieves a satisfactory improvement over TLBO.

A highly sensitive and reversible chemosensor for Hg(2+) detection based on porphyrin-thymine conjugates.

In this study, we demonstrated a highly sensitive, selective, and reversible chemosensor for Hg(2+) determination. This chemosensor was synthesized by direct condensation of thymin-1-ylacetic acid with zinc tetraaminoporphyrin, which has a porphyrin core as the fluorophore and four thymine (T) moieties as the specific interaction sites for Hg(2+) . The probe (4T-ZnP) exhibited split Soret bands with a small peak at 408 nm and a strong band at 429 nm in a dimethylformamide/H2 O (7/3, v/v) mixed solvent as well as a strong emission band at 614 nm. Upon the addition of Hg(2+) , the probe displayed strong fluorescence quenching due to the formation of T-Hg(2+) -T complexes. With the aid of the fluorescence spectrometer, the chemosensor in the dimethylformamide/H2 O (7/3, v/v) mixed solvent (0.3 µM) exhibited a detection limit of 6.7 nM. Interferences from other common cations, such as Co(2+) , K(+) , Sn(2+) , Zn(2+) , Cu(2+) , Ni(2+) , Mn(2+) , Na(+) , Ca(2+) , Mg(2+) , Pb(2+) , and Cd(2+) , associated with Hg(2+) analysis were effectively inhibited.

CLAVATA3 dodecapeptide modified CdTe nanoparticles: a biocompatible quantum dot probe for in vivo labeling of plant stem cells.

CLAVATA3 (CLV3) dodecapeptides function in plant stem cell maintenance, but CLV3 function in cell-cell communication remains less clear. Here, we coupled CLV3 dodecapeptides to synthesized CdTe nanoparticles to track their bioactivity on stem cells in the root apical meristem. To achieve this, we first synthesized CdTe quantum dots (QDs) using a one-pot method, and then evaluated the cytotoxicity of the QDs in BY-2 cells. The results showed that QDs in plant cells must be used at low concentrations and for short treatment time. To make biocompatible probes to track stem cell fate, we conjugated CLV3 dodecapeptides to the QDs by the zero-coupling method; this modification greatly reduced the cytotoxicity of the QDs. Furthermore, we detected CLV3-QDs localized on the cell membrane, consistent with the known localization of CLV3. Our results indicate that using surface-modified QDs at low concentrations and for short time treatment can improve their utility for plant cell imaging.

Colorimetric fluorescent cyanide chemodosimeter based on triphenylimidazole derivative.

In this paper, we demonstrated a highly selective colorimetric chemodosimeter for cyanide anion detection. This chemodosimeter having a triphenylimidazole group as a fluorescent signal unit and a dicyano-vinyl group as a reaction unit was synthesized by the Knoevenagel condensation of 4-(4,5-diphenyl-1H-imidazol-2-yl)benzaldehyde with malononitrile in a reasonable yield. The probe exhibited an intramolecular charge transfer (ICT) absorption band at 420 nm and emission band at 620 nm, respectively. Upon the addition of cyanide anion, the probe displayed a blue-shifted spectrum and loss in color due to the disruption of conjugation. With the aid of the fluorescence spectrometer, the chemodosimeter exhibited a detection limit of 0.11 µM (S/N=3). Interferences from other common anions associated with cyanide anion analysis were effectively inhibited.

[Catalytic kinetic spectrophotometric determination of nickel in alloys].

In (CH2)6N4-HCl buffer solution and in the presence of OP emulsifier trace Ni(II) catalyzes strongly the decolorization reaction of Rhodamine B (RhB) by oxidizing with H2O2, and its catalytic extent is linear with the contents of Ni(II) in a certain range. Based on this study, a novel spectrophotometric method for determining Ni(II) was developed. The results show that the maximum absorption of the complex is at 550 nm, the detection limit of the method is 0.4 microg x L(-1) for Ni(II), and Beer's law is obeyed for Ni(II) in the range of 0-0.3 mg x L(-1). The method has been applied to the determination of Ni in FeNiCr alloys with satisfactory results.

[Spectrophotometric determination of trace chromium in fly ash].

In HNO3 medium the fading reaction of arsenazo III oxidated with Cr2O7(2-) was used as to determine trace Cr in fly ash containing Cr. The results show that the fading reaction has high sensitivity in the medium of 3.2 mol.L-1 nitric acid, the molar absorptivity of 3.9 x 10(6) L.mol-1.cm-1 at 520 nm, and Beer's law is obeyed for Cr (VI) in the range of 0.0-40.0 micrograms.L-1. Contents of Cr in fly ash were determined with satisfactory results.