[en] Measurement method and experience of gross α and gross β for the drinking water of low radioactivity are introduced

[en] This paper describes the conception of RIA and database management, analyzes the testing system of RIA using modular design techniques and related programs in light of actual needs. Achieves the database management functions of the RIA testing system through examples. (authors)

[en] Objective: To explore the value of SPECT in the localization of epileptic foci. Methods: To determine epileptic foci, 34 epilepsy patients who were diagnosed by clinical history and EEG underwent ictal and interictal regional cerebral blood flow (rCBF) imaging with SPECT. Results: Twenty-two of 34 cases showed decreased brain blood flow perfusion on the interictal rCBF images, 28 of those showed increased brain blood flow perfusion on the ictal rCBF images. The patients whose epileptic foci had been localized by SPECT were treated with γ knife. conclusion: SPECT is of great value in the localization of epileptic foci

[en] With the development of frequency stabilization technology in recent years, the linewidth of the 243 nm laser based on a frequency-quadrupled external cavity 972 nm diode laser has been compressed to sub-Hz level by locking to an ultrastable Fabry-Perot cavity. This has provided a new tool in high-resolution spectroscopy for studying the 1S-2S transition in atomic hydrogen. Recent progress in the development of an ultrastable 243 nm laser and its applications in precision hydrogen spectroscopy will be reviewed, as well as some key issues of Fabry-Perot cavity manufacture. (authors)

[en] With the aim at assessment of thermal stabilities of collagen crosslinked with tannic acid under microwave, some thermo-analysis methods have been employed to analyze the properties of the crosslinked product. Meanwhile, for getting some information about the non-thermal effect of microwave on the process, microwave heating with simultaneous cooling (MHSC) method was adopted and compared with water bath heating. The thermal decomposition of the collagen material was characterized by the mass-loss ratio with thermo-gravimetry/derivative thermo-gravimetry curves recorded in nitrogen flow. The crosslinked collagen under MHSC exhibited a higher peak temperature and a lower degree of thermo-oxidative decomposition. The thermal denaturation of the material was determined by the differential scanning calorimetry (DSC) analysis in nitrogen flow. DSC curves showed that microwave gave a higher denaturation temperature and enthalpy, which increased about 3.9 °C and 73.0 J g⁻¹, respectively. The hydrothermal stability of the product was evaluated using the method of micro hot table in glycerol–water condition. The results showed that the shrinkage temperature increased about 3.5 °C under MHSC. In result, microwave gave a higher thermal and hydrothermal stability of the crosslinked collagen, which could be attributed to a stronger bonding of the collagen with tannic acid as a result of microwave non-thermal effect. The results presented here may lay a foundation for the application of microwave in vegetable tanning.

[en] Crankshaft is the key component of internal combustion engine equipment, the machining precision of crankshaft hole has a direct impact on the performance and life of the whole engine. Aiming at the precision machining of crankshaft bore of large medium speed engine block with high precision and multiple crankshaft holes, the inspection tool and straightness measurement method of finishing process on crankshaft holes were studied. Based on the virtual manufacturing technology and the modular design concept of the checking tool and the laser detection and alignment technology, a relationship model describing the matching between the center straightness of the crankshaft hole and the crankshaft deflection is established. A single crankshaft hole shape and position tolerance measurement and multi-crankshaft hole are designed. The special measuring tool for measuring center deflection is verified by experiment to find the compensation law for the deflection of linearity evolution, and should be used in the process of finishing with crankshaft hole. The results of many cutting experiments and laser measurements show that the tool can effectively measure the size deviation and deflection of crankshaft holes, and form a quality control method for crankshaft holes finishing. This study aims to provide a set of measurement methods for crankshaft holes straightness error of large internal combustion engine block.. (paper)

[en] This paper includes five parts. It not only reviews the development history of liquid-sparkling counter but refers that the appearance of coincident circuit is its milestone. The paper summarizes the resembled hard ware and soft ware and soft ware of liquid-sparkling counter of indoor and overseas, and prospects the development of liquid-sparkling counter in our country. (authors)

[en] We demonstrated a robust power-scalable Kerr-lens mode-locked (KLM) operation based on a Yb:YAG thin-disk oscillator. 15-W, 272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity. 247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture. Based on this shorter pulse, high efficient second-harmonic generation (SHG) was performed with a 1.7-mm-long LiB₃O₅ (LBO) crystal. The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour. (paper)

[en] In this work, a column-like nano/micro-scale topography surface has been prepared via trichloro(octyl)silane (TCOS) vapor deposition on the air plasma oxidized polydimethylsiloxane (PDMSOx) surface. TCOS was mixed into n-heptyl alcohol and dimethyl-silicone oil to form a series of mixture. TCOS could anchor to the PDMSOx surface to form column-like nano/micro-scale topography while n-heptyl alcohol and TCOS volatilized to the PDMSOx surface in the subsequent vapor phase process. These surfaces were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared-attenuated total reflection, contact angle measuring system and atomic force microscopy. It was shown that TCOS had been successfully assembled on the polydimethylsiloxane surface. N-heptyl alcohol mixed into alkylsiloxane could regulate the scale and roughness of column-like nano/micro-scale topography.

[en] Zwitterionic materials have been attracting significant attentions due to their excellent non-fouling and biocompatible properties and thus have been widely used in many biomedical applications. However, differences among different types of zwitterionic materials have rarely been investigated and compared. In this work, four types of zwitterionic monomers were systematically studied and compared by testing the properties of the hydrogels. Their hydration, diffusion coefficient of water and mechanical properties were evaluated and analyzed. It was found that poly(carboxybetaine methacrylate) (PCBMA) hydrogel possessed the strongest compressive modulus, while poly(carboxybetaine acrylamide) (PCBAA) hydrogel showed the highest diffusion coefficient of water and highest hydration of water. Compared with other hydrogels, the mesh size of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) hydrogel was the largest. Furthermore, poly(sulfobetaine methacrylate) (PSBMA) hydrogel with disulfide crosslinker degraded faster than the others. Findings in this work provided insights and guidance for the selection of different zwitterionic polymers to suit different applications.