Preparation of silk fibroin–poly(ethylene glycol) conjugate films through click chemistry

Azide silk fibroin (azido SF) and alkyne terminal poly(ethylene glycol) (PEG) 2000 (acetylene-terminal PEG 2000) were synthesized. Azido SF was reacted with acetylene-terminal PEG 2000 to produce films via a copper-mediated 1,3-cycloaddition (‘click’ chemistry) generating a triazole linkage as the networking forming reaction. Through click chemistry, novel silk-based films with various weight ratios were prepared and investigated. Fourier transform infrared, X-ray diffraction and differential scanning calorimetry analyses showed that the ordered association of the PEG molecules is strongly constrained by the presence of the SF molecules and crosslinking and that the presence of acetylene-terminal PEG 2000 in the films induced crystallization to a β-sheet of SF chains.Water content and contact angle measurements indicated that the hydrophilicity of the films increased compared with SF. SF–PEG films exhibited smooth and rough structures, depending on degree of crosslinking and on the weight ratio of SF and PEG, as shown by scanning electron microscopy

Parameters optimization for ferrite slicing based on grey theory

To optimize the parameters of slicing ferrite with high precision diamond ring saw, an orthogonal test is designed with the fabricating surface accuracy and the surface roughness as evaluation indicators and the spindle speed, the feed speed and the tension force as factors. Based on the grey theory, the data analysis and the comprehensive evaluation of the multiple process targets are carried out to obtain an optimized process parameter combination, namely the spindle speed 1 000 r/min, the feed speed 1.0 mm/min and the tension force 90 N. The slicing test results show that the optimized parameter combination can obtain a surface accuracy of PV 7.37 μm and a surface roughness Ra of 0.882 μm, and the slicing surface quality is improved, which verifies the effectiveness and practicability of this method in the optimization of ferrite slicing process parameters

Multi-Repeated Projection Lithography for High-Precision Linear Scale Based on Average Homogenization Effect

A multi-repeated photolithography method for manufacturing an incremental linear scale using projection lithography is presented. The method is based on the average homogenization effect that periodically superposes the light intensity of different locations of pitches in the mask to make a consistent energy distribution at a specific wavelength, from which the accuracy of a linear scale can be improved precisely using the average pitch with different step distances. The method’s theoretical error is within 0.01 µm for a periodic mask with a 2-µm sine-wave error. The intensity error models in the focal plane include the rectangular grating error on the mask, static positioning error, and lithography lens focal plane alignment error, which affect pitch uniformity less than in the common linear scale projection lithography splicing process. It was analyzed and confirmed that increasing the repeat exposure number of a single stripe could improve accuracy, as could adjusting the exposure spacing to achieve a set proportion of black and white stripes. According to the experimental results, the effectiveness of the multi-repeated photolithography method is confirmed to easily realize a pitch accuracy of 43 nm in any 10 locations of 1 m, and the whole length accuracy of the linear scale is less than 1 µm/m