Advanced Materials Research Vol. 924

Abstract: Based on the nanoporous network structure features of silica aerogel, the gas-solid coupled heat transfer model of silica aerogel is analyzed, and the calculation formulas of the gas-solid coupled, the gas thermal conductivity and the heat radiation within the aerogel are derived. The thermal conductivity of pure silica aerogel is calculated according to the derived heat transfer model and is also experimentally measured. Moreover, measurements on the thermal conductivities of silica aerogel composites with different densities at ambient conditions are performed. And finally, a novel design of silica aerogel based integrated structure and thermal insulation used for withstanding the harsh thermal environment on the Martin surface is presented.

Abstract: The lithium niobate integrated optical phase modulator (Y waveguide) is the key device in the digital closed-loop fiber optic gyroscope. However, the half-wave voltage of the lithium niobate changes with the environment temperature, which produces the phase bias drift and ultimately decreases the accuracy of FOG. In this manuscript, the thermal resistor is introduced in the amplification part in the driving circuits of Y waveguide. Due to the characteristic of the thermal resistor, the magnitude of driving voltage on Y waveguide changed with temperature to compensate the electro-optic effects temperature drift of the lithium niobate. This method was proved to improve the performance of fiber optic gyroscopes conveniently in experiment.

Abstract: With the progress in science and technology, the dynamic security, the reliability, the accuracy and the stability of delay composition in complicated condition attracts more and more attentions. Traditional delay composition can not meet our requirements of the reliability and security. Its the first time carbon nanotubes (CNTs) with high heat conductivity and high intensity are added into the system of Tungsten type delay composition and boron type delay composition. CNTs were mixed into W and B by ball-milling method. Particle size analysis and transmission electron microscopy (TEM) are utilized to analyse the size structure and dispersity of W/ CNTs and B/ CNTs. Optimum conditions of preparing W/CNTs and B/CNTs were found to apply to fuel agent of delay composition. In addition, burning rate and delay precision of the four delay charges (BaCrO₄/W, BaCrO₄/W/CNTs,BaCrO₄/B and BaCrO₄/B/CNTs delay compositions) were reseached. Results show that delay compositions added to CNTs had higher burning rate and better delay precision than original delay charges (burning rate of BaCrO₄/W/CNTs was as much as 3-4 times higher than that of BaCrO₄/W under the same constraints. Meanwhile, burning rate of BaCrO₄/B/CNTs is 2 times higher than that of BaCrO₄/B). Especially, the ignition reliability of charges added to CNTs were improved while charge density exceeds about 6000 Kg/m³. So the addition of certain amount of CNTs in the delay compositions can obviously increase the burning rate and the ignition reliability of delay compositions.

Abstract: Thermoactinomyces sacchari was isolated from hot water springs.Then by utilizing the solid state fermentation techniques, amylase was obtained, which was partially purified. The partially pu rified enzyme was then used to remove the starch size from cloth. Effective enzymatic desizing requires the strict control of pH, temperature, water hardness, electrolyte addition and choice of surfactant. It was observed that maximum removal 7.5 g was achieved by soaking the cloth in 100 ml of 0.1M HCl for 2 hours. A maximum of 98.4desizing was obtained after 90 minutes at 55oC. A maximum desizing of 98.9 was obtained after 60 minutes of incubation at 55oC.A maximum desizing of100% was obtained at pH 6.0 at 55oC for 60 minutes. At lower and higher values desizing decreased. When cotton pieces were soaked for 60 minutes at pH 6.0, maximum desizing (100%) was obtained at 60oC.

Abstract: In o rder to research the influence of anion additives/ CeO₂ on cabbage seeds, taking cabbage seeds as the test material. This paper detected the seeds' germination percentage and protein content by respectively adding unique concentration of anion additives and CeO₂ in soil. The results show that different anion additives have distinct influences on seed's growth in the same situation. To be more specific, 1040 can noticeably improve seeds' germination percentage and protein content. Moreover, different contents of 1040 could have various impacts on seeds' germination percentage and protein content. Furthermore, precise content of CeO₂ can also significantly improve seeds' germination rate and protein accumulation.

Abstract: Lift-off process is a critical combined process in semiconductor manufacturing field. However, traditional methods of lift-off process can hardly be carried out in Ultraviolet Nanoimprint Lithography due to the poor solubility of ultraviolet imprint resist. In this paper, a modified lift-off process using a multi-layer transfer method has been introduced to solve this problem. More importantly, this method could bring an improved result even if the aspect ratio of hard stamp is small. By applying this method, we succeeded in fabricating pillar photonic crystal stamp using hole pattern mother stamp and using the newly defined stamp to fabricate nanopattern sapphire substrate. Depth of the nanopattern is 250nm and the profile of the pattern is pyramid type which is very suitable for subsequent epitaxy.

Abstract: In this paper, we fabricated the 4-aminobenzenethiol modified gold nanoparticles onto polymer spheres as SERS substrate to selectively detect 2,4,6-trinitrotoluene (TNT) explosives. The gold nanoseeds were fixed on polymer surface by reduction of HAuCl₄·3H₂O with sodium citrate. About 60~100nm nanoparticles were formed from the previous seeds and self-assembled by 4-aminobenzenethiol. The functionalized gold nanopartilces aggregation coated on large polymer sphere surface not only absorbed more TNT molecules via conjugation system, but also generated numerous "hot spots". It was demonstrated that this substrate displayed high SERS activity for TNT detection. It could also be anticipated that the aforementioned material would be used for fast and sensitive SERS detection of TNT in real-world situation. Keywords: gold nanopartilces, SERS, TNT, functionalization

Abstract: Rod-like SBA-15 mesoporous materials were synthesized and modified using two-step process through aminopropyl and glutaraldehyde. Aminopropyl was first covalently bonded to silanol groups present on the surface of mesoporous silica. Successively, the reaction of aldehyde with aminopropyl was followed. Immobilizations of Porcine pancreatic lipase (PPL) onto functionalized SBA-15 (NH₂-SBA-15-PPL and G-SBA-15-PPL) have been achieved. Relative activities and reusability of NH₂-SBA-15-PPL and G-SBA-15-PPL for triacetin hydrolysis have been studied.

Abstract: The sptitching measuring method applied in large-aperture aspheric surface optical elements can expand the range of precision measuring instrument. And the key point is developing the technique for high precision measuring data processing. To deal with the problem of cumulative errors which existed in the process of multi-section stitching, datum-transformation method was proposed, according to the characteristic of stitching measurement. The stitching measuring experiments were carried out based on Talysurf PGI 1240 profilometer of Taylor Hobson Company to verify the purpose for eliminating cumulative errors. The results show that datum-transformation method is feasible with the characteristic such as fast speed, high precision, and good operability.