Magnetic nanowires via template electrodeposition

The magnetic NiFe_x nanowires were prepared via template-guided electrodeposition. Anodized nanoporous aluminum was used as a template. The pore density and dimensions of alumina templates can be controlled by anodization conditions. Magnetic nanorods (or nanowires) with various aspect ratios were prepared by controlling the electrodeposition time. SEM and TEM micrographs revealed the wire and rod shape morphologies with 50 nm in diameter and 1.5 ~ 10 μm in length. Elemental analysis and ESCA studies suggested that NiFe₃ magnetic alloy was formed. The X-ray diffraction pattern indicates that all the nanowires are stabilized in a BCC structure with a [1 1 0] texture oriented along the long axis of the nanowires. The magnetic measurement showed no hysteresis loops for the whole aspect ratios of the nanowires. Nevertheless, the magnetization is more temperature sensitive for nanowires with lower aspect ratio. This is caused by the fact that the easy magnetization axis is always parallel to the long axis of the nanowires.     

Palladium complexes of bidentate pyridine N‐heterocyclic carbenes: Optical resolution,antimicrobial and cytotoxicity studies

A series of bidentate pyridine‐functionalized palladium N‐heterocyclic carbene (Pd NHC) complexes with various wingtip substituents (R = methyl, phenyl and tert‐butyl) have been synthesized and evaluated for their potential biomedical applications as antimicrobials and antiproliferative drug candidates. The obtained Pd NHC complexes were applied in a standard broth microdilution assay for determination of their antimicrobial activities against thirteen strains of pathogenic microorganisms. In addition to that, cytotoxic activities of the Pd NHC complexes were also evaluated against three human cancer cell lines, namely breast (MCF‐7), colon (HCT116) and oral (H103) cancer cells, using a standard MTT assay. Upon coordination to palladium, the Pd NHC complexes show significant antimicrobial activities with minimum inhibitory concentrations in the micromolar range, and they are cytotoxic to the tested carcinomas with IC₅₀ ranging from 13 to 38 μM. Evidences for influence of both wingtip substituents and optical isomerism on the biological activities of the complexes have been found.     

Divergent Chemistry Paths for 3D and 1D Metallo-Covalent Organic Frameworks (COFs)

The marriage of dynamic covalent chemistry (DCC) and coordination chemistry is a powerful tool for assembling complex architectures from simple building units. Recently, the synthesis of woven covalent organic frameworks (COFs) with topologically fascinating structures has been achieved using this approach. However, the scope is highly limited and there is a need to discover new pathways that can assemble covalently linked organic threads into crystalline frameworks. Herein, we have identified branching pathways leading to the assembly of three-dimensional (3D) woven COFs or one-dimensional (1D) metallo-COFs (mCOFs), where the mechanism is underpinned by the absence or presence of ligand exchange.     

Improved Carroll's hyperelastic model considering compressibility and its finite element implementation

Acta Mechanica Sinica - In engineering component design, material models are increasingly used in finite element simulations for an expeditious and less costly analysis of the design prototypes. As...     

Mechanical Stimuli for Left Ventricular Growth During Pressure Overload

Background

The mechanical stimulus (i.e., stress or stretch) for growth occurring in the pressure-overloaded left ventricle (LV) is not exactly known.

Objective

To address this issue, we investigate the correlation between local ventricular growth (indexed by local wall thickness) and the local acute changes in mechanical stimuli after aortic banding.

Methods

LV geometric data were extracted from 3D echo measurements at baseline and 2 weeks in the aortic banding swine model (n?=?4). We developed and calibrated animal-specific finite element (FE) model of LV mechanics against pressure and volume waveforms measured at baseline. After simulation of the acute effects of pressure-overload, the local changes of maximum, mean and minimum myocardial stretches and stresses in three orthogonal material directions (i.e., fiber, sheet and sheet-normal) over a cardiac cycle were quantified. Correlation between mechanical quantities and the corresponding measured local changes in wall thickness was quantified using the Pearson correlation number (PCN) and Spearman rank correlation number (SCN).

Results

At 2 weeks after banding, the average septum thickness decreased from 10.6?±?2.92 mm to 9.49?±?2.02 mm, whereas the LV free-wall thickness increased from 8.69?±?1.64 mm to 9.4?±?1.22 mm. The FE results show strong correlation of growth with the changes in maximum fiber stress (PCN?=?0.5471, SCN?=?0.5111) and changes in the mean sheet-normal stress (PCN?=?0.5266, SCN?=?0.5256). Myocardial stretches, however, do not have good correlation with growth.

Conclusion

These results suggest that fiber stress is the mechanical stimuli for LV growth in pressure-overload.

     

The self-assembly of porphine molecules on NaCl pre-covered Cu(110) surface

The self-assembly of porphine molecules on NaCl pre-covered Cu(110) surface has been investigated at a single molecular level by scanning tunneling microscopy. The pre-grown NaCl stripe pattern has been partly interrupted due to the adsorption of porphine molecules at RT. Annealing the sample at 333 K and 423 K gradually promotes the formation of self-assembly network composed of porphine molecules and Cu atoms. Annealing at 473 K helps to convert this self-assembly structure into organometallic nanoribbon through C–Cu–C connecting.