A New L-Proline Amide Hydrolase with Potential Application within the Amidase Process

L-proline amide hydrolase (PAH, EC 3.5.1.101) is a barely described enzyme belonging to the peptidase S33 family, and is highly similar to prolyl aminopeptidases (PAP, EC. 3.4.11.5). Besides being an S-stereoselective character towards piperidine-based carboxamides, this enzyme also hydrolyses different L-amino acid amides, turning it into a potential biocatalyst within the Amidase Process. In this work, we report the characterization of L-proline amide hydrolase from Pseudomonas syringae (PsyPAH) together with the first X-ray structure for this class of L-amino acid amidases. Recombinant PsyPAH showed optimal conditions at pH 7.0 and 35 °C, with an apparent thermal melting temperature of 46 °C. The enzyme behaved as a monomer at the optimal pH. The L-enantioselective hydrolytic activity towards different canonical and non-canonical amino-acid amides was confirmed. Structural analysis suggests key residues in the enzymatic activity.

Amidine- and Amidoxime-Substituted Heterocycles: Synthesis, Antiproliferative Evaluations and DNA Binding

The novel 1,2,3-triazolyl-appended N- and O-heterocycles containing amidine 4–11 and amidoxime 12–22 moiety were prepared and evaluated for their antiproliferative activities in vitro. Among the series of amidine-substituted heterocycles, aromatic diamidine 5 and coumarine amidine 11 had the most potent growth-inhibitory effect on cervical carcinoma (HeLa), hepatocellular carcinoma (HepG2) and colorectal adenocarcinoma (SW620), with IC50 values in the nM range. Although compound 5 was toxic to non-tumor HFF cells, compound 11 showed certain selectivity. From the amidoxime series, quinoline amidoximes 18 and 20 showed antiproliferative effects on lung adenocarcinoma (A549), HeLa and SW620 cells emphasizing compound 20 that exhibited no cytostatic effect on normal HFF fibroblasts. Results of CD titrations and thermal melting experiments indicated that compounds 5 and 10 most likely bind inside the minor groove of AT-DNA and intercalate into AU-RNA. Compounds 6, 9 and 11 bind to AT-DNA with mixed binding mode, most probably minor groove binding accompanied with aggregate binding along the DNA backbone.

On PVC-PP composite matrix for 4D applications: Flowability, mechanical, thermal, and morphological characterizations

Thermoplastics such as; polyvinyl chloride (PVC) and polypropylene (PP) have applications in different sectors such as; automobile, aerospace, biomedical, textile etc. due to cost-effectiveness, biodegradability, high mouldability, easy availability and good mechanical properties. The shape memory performances of these thermoplastics are crucial for extending the four-dimensional (4D) printing applications. But hitherto little has been reported on flowability, mechanical, thermal, morphological and shape memory properties of PVC-PP composite. In this study, twin-screw compounding has been employed on PVC and PP thermoplastics (in single and blended form) to prepare feedstock filaments for fused filament fabrication (FFF). The investigations have been made for flowability (melt flow index (MFI), mechanical (tensile strength and elongation), thermal (melting point) morphological, Fourier transform infrared spectroscopy (FTIR) analysis, and shape memory effect on different feedstock filaments (prepared with neat PVC, 75%PVC-25%PP, 50%PVC-50%PP, 25%PVC-75%PP, and neat PP). The results have been supported by fracture analysis of photomicrographs obtained from scanning electron microscopy (SEM). The results of the study suggested that tensile strength was maximum for 50%PVC-50%PP (23.57 MPa) and minimum for neat PP (8.89 MPa). Further percentage shape recovery was observed maximum for neat PVC and minimum for neat PP.

Morphological Study of Nanostructures Induced by Direct Femtosecond Laser Ablation on Diamond

High spatial frequency laser induced periodic surface structure (HSFL) morphology induced by femtosecond laser with 230 fs pulse duration, 250 kHz repetition rate at 1030 nm wavelength on CVD diamond surface is investigated and discussed. The spatial modification was characterized and analyzed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and 2D-Fast Fourier Transform (2D-FFT). We studied the effect of pulse number and laser power on the spatial development of nanostructures, and also deduced the impact of thermal accumulation effect on their morphology. A generalized plasmonic model has been used to follow the optical evolution of the irradiated surface and to determine the periodic value of the nanostructures. We suggest that non-thermal melting and plasmonic excitation are the main processes responsible for the formation of HSFL-type nanostructures.

Fast Fabrication of Fishnet Optical Metamaterial Based on Femtosecond Laser Induced Stress Break Technique

To speed up the fabrication of optical metamaterials by making use of the fast speed advantage of femtosecond laser preparation, a metamaterial appropriate for femtosecond laser processing was designed, and the interaction between femtosecond laser and metal-dielectric-metal fishnet stacks was investigated in detail. Two kinds of processing mechanisms, thermal melting and stress break, were revealed during the fabrication. The thermal melting process, dominated by the interaction of femtosecond laser with metals, makes the upper and lower metal layers adhere to each other, which leads to the magnetic resonance impossible. The stress break process, dominated by the interaction of femtosecond laser with dielectrics, can keep the upper and lower metal coatings isolated. Fishnet optical metamaterial was fabricated by femtosecond laser-induced stress break technique, using back side ablation, high numerical aperture and super-Gaussian beam. The resolution and speed can reach 500 nm, and 100 units/s, respectively. Spectrophotometer measurement results proved that the magnetic resonances were found in the fishnet nanostructure. The theoretical refractive index of the metamaterial on a glass substrate reached −0.12 at the wavelength of 3225 nm. It proved that femtosecond laser-induced stress break was a good and fast tool during the fabrication of optical metamaterials.