Wetting state and mechanical property alteration for the Fe3Si films using rapid thermal annealing under various temperatures.

The current research demonstrates the modification of the wetting behavior and mechanical features as well as structure and morphology of Fe3Si films created via facing target sputtering by the rapid thermal annealing (RTA) with the set RTA temperatures (TRTA) of 200, 400, 600, and 800 °C. Following the RTA process, the crystallinity of Fe3Si developed under 400 °C or below. At the 600 °C and 800 °C TRTA, new crystal orientations emerged for FeSi and then ß-FeSi2, respectively. Together with composition results, the Fe3Si films were proven to change into FeSi and then FeSi2 under a high TRTA regime. At temperatures of 600 °C and 800 °C, large crystallites, including the scraggly interface, were observed. The root-mean-square roughness roughened slightly according to the RTA process at TRTA of 600 °C or above. The hydrophobic properties of the Fe3Si film surfaces became hydrophilic after the RTA procedure at a TRTA value above 400 °C. The hardness value of the Fe3Si films evidently increased through RTA at 600 °C and 800 °C. Thus, above 400 °C, the RTA process significantly alters the physical features of as-created Fe3Si films.

Discovery and Genetic Code Expansion of a Polyethylene Terephthalate (PET) Hydrolase from the Human Saliva Metagenome for the Degradation and Bio-Functionalization of PET.

We report a bioinformatic workflow and subsequent discovery of a new polyethylene terephthalate (PET) hydrolase, which we named MG8, from the human saliva metagenome. MG8 has robust PET plastic degradation activities under different temperature and salinity conditions, outperforming several naturally occurring and engineered hydrolases in degrading PET. Moreover, we genetically encoded 2,3-diaminopropionic acid (DAP) in place of the catalytic serine residue of MG8, thereby converting a PET hydrolase into a covalent binder for bio-functionalization of PET. We show that MG8(DAP), in conjunction with a split green fluorescent protein system, can be used to attach protein cargos to PET as well as other polyester plastics. The discovery of a highly active PET hydrolase from the human metagenome-currently an underexplored resource for industrial enzyme discovery-as well as the repurposing of such an enzyme into a plastic functionalization tool, should facilitate ongoing efforts to degrade and maximize reusability of PET.

Diamond-Like Carbon Thin Film Electrodes for Microfluidic Bioelectrochemical Sensing Platforms.

This work aims to utilize diamond-like carbon (DLC) thin films for bioreceptor immobilization and amperometric biosensing in a microfluidic platform. A specific RF-PECVD method was employed to prepare DLC thin film electrodes with desirable surface and bulk properties. The films possessed a relatively high sp2 fraction, a moderate electrical conductivity (7.75 × 10-3 S cm-1), and an optical band gap of 1.67 eV. X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy revealed a presence of oxygen-containing functional groups on the DLC surface. The DLC electrodes were integrated into polydimethylsiloxane (PDMS) microfluidic electrochemical cells with the channel volume of 2.24 µL. Glucose oxidase (GOx) was chosen as a model bioreceptor to validate the employment of DLC electrodes for bioelectrochemical sensing. In-channel immobilization of glucose oxidase (GOx) at the DLC surface was realized through carbodiimide covalent linkages. Enzyme bound DLC electrode was confirmed with the redox potential at around -79 mV vs NHE in 0.1 M phosphate buffer pH 7.4. Amperometric flow-injection glucose sensing at a potential of -0.45 V vs Ag in the absence of standard redox mediators showed the increase of current response upon increasing the glucose concentration. The sensing mechanism is based on the reduction process of H2O2 liberated from the enzymatic activity. The proposed model for the catalytic H2O2 reduction to H2O on DLC electrodes was attributed to the dissociation of C-O bonds at the DLC surface.

Plasma nano-modification of poly(ethylene terephthalate) fabric for pigment adhesion enhancement.

Poly(ethylene terephthalate) (PET) fabrics were modified by treating with radio frequency (RF) plasma of different gases, including argon (Ar), nitrogen (N2), oxygen (O2) and sulfur hexafluoride (SF6), under varied power (50-150 watt) and time period (0.5-20 min). Observations indicated that plasma has affected the morphology and roughness of PET fiber surface in the nano-scale level. After plasma treatment, test patterns were printed by inkjet printer directly onto the sample surface. The enhancement of color printing performance on PET fabric by plasma treatment was evaluated by color spectroscopy. The surface nano-modified PET fabrics by Ar, N2, O2, and SF6 plasmas all exhibited enhanced color yield. AFM, SEM, FTIR-ATR and XPS results suggested that the improved pigment color yield was neither clearly contributed by the wettability of the fabrics nor the polar group induced onto the fiber surfaces but rather mainly by the alteration of surface roughness.

Coating of diamond-like carbon nanofilm on alumina by microwave plasma enhanced chemical vapor deposition process.

Diamond-like carbon (DLC) nanofilms with thickness varied from under one hundred to a few hundred nanometers have been successfully deposited on alumina substrates by microwave plasma enhanced chemical vapor deposition (MW-PECVD) process. To obtain dense continuous DLC nanofilm coating over the entire sample surface, alumina substrates were pre-treated to enhance the nucleation density. Raman spectra of DLC films on samples showed distinct diamond peak at around 1332 cm(-1), and the broad band of amorphous carbon phase at around 1550 cm(-1). Full width at half maximum height (FWHM) values indicated good formation of diamond phase in all films. The result of nano-indentation test show that the hardness of alumina samples increase from 7.3 +/- 2.0 GPa in uncoated samples to 15.8 +/- 4.5-52.2 +/- 2.1 GPa in samples coated with DLC depending on the process conditions. It is observed that the hardness values are still in good range although the thickness of the films is less than a hundred nanometer.

Surface nanomodification of cotton fiber for flame retardant application.

This paper presents efficient surface modification methodology to increase fire resistance properties of cotton by radio frequency (RF) plasma-induced graft copolymerization of vinyl phosphate ester as nanometer residue structure onto cotton surface. Methacryloyloxyethyl diphenyl phosphate (MEDP) monomer was synthesized and grafted onto the surface of cotton fabric by argon RF plasma at ambient temperature. Under optimum RF power (30 W), amounts of MEDP and N,N methylenebisacrylamide cross linking agent were varied to obtain optimum graft copolymerization conditions. Untreated and treated cotton were characterized by attenuated total reflectance infrared (ATR-IR) spectroscopy to investigate their functional group characteristics. This showed a strong covalent attachment between the surface of cotton and flame retardant material as the carbonyl functionality of the MEDP was clearly observed in the spectra. Scanning electron microscopic (SEM) analysis also showed grafted material as nanometer residue on cotton surface. Thermogravimetric analysis (TGA) revealed that the decomposition of phosphorus compound which occurs at lower temperature than the cotton itself resulted in the formation of char which covers cotton surface. This protects the fabric surface from further burning, therefore, higher amounts of remaining materials were observed as char in all cases. Furthermore, limiting oxygen index (LOI) had increased from 19 in untreated to 28 in grafted cotton. Detailed analysis on structural and thermal properties as well as surface grafting efficiency are presented.