Syntheses,characterization, and antimicrobial properties of nickel(II) dithiocarbamate complexes containing NiS4 and NiS2PN moieties

Three Ni(II) dithiocarbamate complexes, [Ni(buphdtc)₂] (1), [Ni(buphdtc)(PPh₃)(NCS)] (2) and [Ni(buphdtc)(PPh₃)(NC)] (3) (where bu = butyl and ph = phenyl), were synthesized and characterized by elemental analysis, UVvis, and FTIR spectroscopies. Complexes 1 and 2 were further characterized by single-crystal X-ray structural analysis. The single-crystal X-ray structural analysis indicates a slightly distorted square planar geometry. In 2 and 3, the influences of the auxiliary ligands (PPh₃, NCS, and NC) on their steric and electronic properties were observed. Thermal studies of the complexes showed decomposition starting at 250–300 °C, leading to formation of nickel sulfide phases around 400 °C. The complexes were screened against some bacteria strains, Staphylococcus aureus, Streptococcus pneumoniae, Bacillus subtilis, Escherichia coli, Klebsiella oxytoca and Pseudomonas aeruginosa, and two fungi species, Aspergillus niger and Fusarium oxysporum. The complexes showed moderate-to-strong antimicrobial potentials, with [Ni(buphdtc)₂] (1) displaying the best antimicrobial activity. Fluconazole and streptomycin were used as reference drugs for antifungal and antibacterial assays, respectively.     

Crystal structures,antibacterial, antioxidant and nucleic acid interactions of mononuclear,and tetranuclear palladium(II) complexes containing Schiff base ligands

Two new palladium complexes, [Pd(dpbs)Cl] (1) and [Pd₄(dbbs)₄] (2) (where (dpbs)₂ = o,o′-(N,N′-dipicolinyldene)diazadiphenyl disulfide and (dbbs)₂ = N,N′-(1,1′-dithio-bis(phenylene))-bis(salicylideneimine)), have been synthesized and characterized by analytical and spectral (electronic, IR, ¹H, ¹³C spectroscopy) techniques. The structures of 1 and 2 have been solved by single-crystal X-ray diffraction experiments, which indicate distorted square planar coordination geometries around palladium(II) by O, N, and S donors. The metal chelates have been screened for their antibacterial and antioxidant activities, and compared with their respective ligands. The binding properties of the complexes have been studied by electronic absorption, emission spectroscopy, and viscosity measurements. The competitive fluorescence study with ethidium bromide and the effect of iodide concentration on ?uorescence of the complex-DNA system have been investigated. All these experimental results suggest that palladium complexes strongly bind to DNA, presumably via groove binding. The thermodynamic parameters, enthalpy change (ΔH°), and entropy change (ΔS°) were calculated by the Van’t Hoff equation, suggesting hydrogen bonds play a predominant role in the binding of complexes to DNA.     

菲啶和三苯基膦的Cu(Ⅰ)/Cu(Ⅱ)配合物的合成、表征和X射线晶体结构分析

以三苯基膦（PPh₃）为共配体,合成了2种新的铜（Ⅰ）和铜（Ⅱ）与菲啶（Phend）的配合物,其组成为[Cu（κ¹-Phend）₂Cl₂]（1）和[Cu₂（κ¹-Phend）₂（κ¹-PPh₃）₂（μ-Cl）₂]（2）。这些配合物的结构通过元素分析、摩尔电导率、FT-IR、UV-Vis和单晶X射线衍射进行了研究。典型配合物1的X射线衍射分析显示,Cu（Ⅱ）配位构型为扭曲的平面四方形,而双核配合物2的Cu（Ⅰ）中心为含μ-Cl^-离子的不规则四面体构型。FT-IR谱、元素分析以及UV-Vis谱证实了它们的成分、几何形状和配体相互作用。2种配合物的结构通过密度泛函理论（DFT）计算进行了优化,以解释电子光谱特性。     

Coordination of bidentate aniline derivatives to the fac-[Re(CO)3] core

A series of rhenium(I) tricarbonyl complexes, containing bidentate derivatives of aniline, was synthesized and structurally characterized. With 1,2-diaminobenzene (Hpda) the ‘2+1’ complex salt fac-[Re(CO)₃(Hpda)₂]Br was isolated. The neutral complex [Re(CO)₃(Hapa)Br] was formed with 2-aminodiphenylamine (Hapa) as ligand. 2-Aminophenol (Hopa) also produced the neutral ‘2+1’ complex [Re(CO)₃(opa)₂(Hopa)], but with 2-mercaptophenol (Hspo) the bridged dimer [Re₂(CO)₇(spo)₂] was found. In the complex [Re(CO)₃(Htpn)Br] (Htpn = N′-{(2-methylthio)benzylidene}benzene-1,2-diamine) the potentially tridentate ligand Htpn is coordinated via the methylthio sulfur and imino nitrogen atoms only, with a free amino group.     

Differential evolution for dynamic environments with unknown numbers of optima

This paper investigates optimization in dynamic environments where the numbers of optima are unknown or fluctuating. The authors present a novel algorithm, Dynamic Population Differential Evolution (DynPopDE), which is specifically designed for these problems. DynPopDE is a Differential Evolution based multi-population algorithm that dynamically spawns and removes populations as required. The new algorithm is evaluated on an extension of the Moving Peaks Benchmark. Comparisons with other state-of-the-art algorithms indicate that DynPopDE is an effective approach to use when the number of optima in a dynamic problem space is unknown or changing over time.     

On Extensions of Chain Algebras and Atoms of the Lattice of Radicals

In this article we study the problem when a left distributive algebra over a field determines an atom of the lattice of all radicals of rings. We show that this problem is strictly connected with the problem of describing extensions of left chain algebras and give a characterization of left chain algebras determining atoms.     

Polaron effects on the thermal conductivity of zigzag carbon nanotubes

Thermal conductivity of metallic zigzag carbon nanotube is investigated in the context of Holstein model. Green's function approach is implemented to calculate the electronic contribution of thermal conductivity as a function of radius of carbon nanotube, temperature and electron phonon coupling strength. Our results show that electronic thermal conductivity increases as a function of temperature at low temperature and gets a maximum value then decays at high temperature. Also the effect of radius of both metallic and semiconductor zigzag carbon nanotube on the thermal conductivity is studied. Our results show thermal conductivity increases when CNT diameter increases and decreases with electron phonon interaction strength.     

Dependence of surface distribution of self-assembled InSb nanodots on surface morphology and spacer layer thickness

Self-assembled InSb nanodots (NDs) were grown on a GaSb (1 0 0) substrate using metal-organic vapour phase epitaxy (MOVPE). The effects of etching depth of the substrate and thickness of the GaSb buffer layer on the density and size distribution of single and double layer dots were studied for detector applications. The etch depth of the substrate was varied up to 30 μm. In this particular study, the dots were grown at 450 °C and the GaSb spacer thickness was varied between 50 nm and 200 nm. The optimum substrate etch depth was found to be 30 μm while the best spacer thickness was found to be 200 nm.     

Characterization of cell mismatch in a multi-crystalline silicon photovoltaic module

In this study the causes and effects of cell mismatch were identified in a multi-crystalline silicon photovoltaic module. Different techniques were used to identify the causes of the mismatch, including Electroluminescence (EL) imaging, Infrared (IR) imaging, current–voltage (I–V) characteristics, worst-case cell determination and Large Area Laser Beam Induced Current (LA-LBIC) scans. In EL images the cracked cells, broken fingers and material defects are visible. The presence of poorly contacted cells results in the formation of hot-spots. LA-LBIC line scans give the relative photoresponse of the cells in the module. However, this technique is limited due to the penetration depth of the laser beam. The worst case cell determination compares the I–V curves of the whole module with the I–V curve of the module with one cell covered, allowing the evaluation of the performance of each cell in a series-connected string. These methods allowed detection of the poorly performing cells in the module. Using all these techniques an overall view of the photoresponse in the cells and their performance is obtained.     

The origin of a peak in the reststrahlen region of SiC

A peak in the reststrahlen region of SiC is analyzed in order to establish the origin of this peak. The peak can be associated with a thin damaged layer on the SiC wafers, and a relation is found between surface roughness and the height of this peak, by modeling the damaged layer as an additional layer when simulating the reflectivity from the wafers.