Synthesis and biological properties of palladium(II) cyclometallated compounds derived from ( E )-2-((4-hydroxybenzylidene)amino)phenol

( E )-2-((4-hydroxybenzylidene)amino)phenol (iminophenol a ) reacted with Pd(OAc) 2 giving place to com- pound 1a , in which the iminophenol was bonded to palladium(II) in a κ3 - C ortho ,N,O ortho tridentate chelat- ing mode. Thus, 1a was formed by neutral mononuclear units of schematic formula Pd(C,N,O), consisting of two fused five-membered metallacycles. Self-assembly of the Pd(C,N,O) units gave place to the polynu- clear structure of 1a . Treatment of 1a with PPh 3 or PPh 2 CH 2 CH 2 PPh 2 in molar ratio Pd(II)/PPh 3 = 1/1 or Pd(II)/PPh 2 CH 2 CH 2 PPh 2 = 2/1 produced the mononuclear or dinuclear compound of schematic formula [Pd(C,N,O)(PPh 3 )] ( 2a ) or {[P d (C,N,O)] 2 ( μ2 -PPh 2 CH 2 CH 2 PPh 2 )} ( 3a ), respectively. Compounds a were char- acterized by elemental analysis, high resolution ESI-( + ) mass spectrometry, IR, and NMR. In addition, the crystal structure of the adducts 2a ·2(CH 2 Cl-CH 2 Cl) and 3a ·5(dmso) was determined by single crystal X- ray diffraction analysis. Most compounds a were noncytotoxic or poorly cytotoxic. Nonetheless, 2a was moderately cytotoxic against the MCF-7 breast and HCT-116 colon human cancer cell lines, and presented very low cytotoxicity towards normal skin human BJ cells. Compounds a showed moderate antibacterial activity against some Gram-positive ( B. subtilis and S. aureus ) and Gram-negative ( E. coli ) bacterial strains, and displayed also moderate antioxidant activity, producing 3a the best antioxidant activity. 1a changed the electrophoretic mobility of the pBluescript SK + plasmid DNA. This change followed the pattern of cisplatin , but it started at a concentration twenty times higher than with cisplatin . Moreover, compounds 1a - 3a inhibited topoisomerase IIα at concentrations of 10, 50 and 25 μM, respectively

Cyclopalladated and cycloplatinated benzophenone imines: antitumor, antibacterial and antioxidant activities, DNA interaction and cathepsin B inhibition

The antitumor, antibacterial and antioxidant activity, DNA interaction and cathepsin B inhibition of cyclo-orthopalladated and -platinated compounds [Pd(C,N)]2(μ-X)2 [X = OAc (1), X = Cl (2)] and trans-N,P-[M(C,N)X(PPh3)] [M = Pd, X = OAc (3), M = Pd, X = Cl (4), M = Pt, X = Cl (5)] are discussed [(C,N)= cyclo-orthometallated benzophenone imine]. The cytotoxicity of compound 5 has been evaluated towards human breast (MDA-MB-231 and MCF-7) and colon (HCT-116) cancer cell lines and that of compounds 1-4 towards the HCT-116 human colon cancer cell line. These cytotoxicities have been compared with those previously reported for compounds 1-4 towards MDA-MB-231 and MCF-7 cancer cell lines. Compound 3 and 4 were approximately four times more active than cisplatin against the MDA-MB-231 andMCF-7 cancer cell lines, and compound 5, was approximately four times more potent than cisplatin against the HCT-116 cancer cell line. The antibacterial activity of compounds 1-5 was in between the ranges of activity of the commercial antibiotic compounds cefixime and roxithromycin. Complexes 1-2 and 4-5 presented also antioxidant activity. Compounds 1-5 alter the DNA tertiary structure in a similar way to cisplatin, but at higher concentration, and do not present a high efficiency as cathepsin B inhibitors. Compound 5 has not been previously described, and its preparation, characterization, and X-ray crystal structure are reported

Chitosan–Starch–Keratin composites: Improving thermo-mechanical and degradation properties through chemical modification

The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73 % for chitosan-starch matrix up to 16 % for the composites with 5wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiat-ing chitosan–starch films with sustainable featuresChitosan–starch polymers are reinforced with different keratin materials obtained from chicken feather. Keratin materials are treated with sodium hydroxide; the modified surfaces are rougher in comparison with untreated surfaces, observed by Scanning Electron Microscopy. The results obtained by Differential Scanning Calorimetry show an increase in the endothermic peak related to water evaporation of the films from 92 °C (matrix) up to 102–114 °C (reinforced composites). Glass transition temperature increases from 126 °C in the polymer matrix up to 170–200 °C for the composites. Additionally, the storage modulus in the composites is enhanced up to 1614 % for the composites with modified ground quill, 2522 % for composites with modified long fiber and 3206 % for the composites with modified short fiber. The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73 % for chitosan-starch matrix up to 16 % for the composites with 5wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiat-ing chitosan–starch films with sustainable featuresUniversidad Autónoma del Estado de México Tecnológico Nacional de México, Instituto Tecnológico de Querétaro Universidad Nacional Autónoma de México Tecnológico Nacional de México, Instituto Tecnológico de Celaya Universidad Autónoma de Cd. Juáre

A review of numerical analysis of friction stir welding

Friction stir welding is a relatively new solid-state joining technique which is widely adopted in different industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a highly complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints and their three dimensional nature make it difficult to develop an overall system of governing equations for theoretical analyzing the behavior of the friction stir welded joints. The experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used since the 2000s. This paper reviews the latest developments in the numerical analysis of friction stir welding processes, microstructures of friction stir welded joints and the properties of friction stir welded structures. Some important numerical issues such as materials flow modeling, meshing procedure and failure criteria are discussed. Numerical analysis of friction stir welding will allow many different welding processes to be simulated in order to understand the effects of changes in different system parameters before physical testing, which would be time-consuming or prohibitively expensive in practice. The main methods used in numerical analysis of friction stir welding are discussed and illustrated with brief case studies. In addition, several important key problems and issues remain to be addressed about the numerical analysis of friction stir welding and opportunities for further research are identified