Altered age-hardening behavior in the ultrafine-grained surface layer of Mg-Zn-Y-Ce-Zr alloy processed by sliding friction treatment

To gain insight into the ageing behavior of ultrafine grain(UFG)structure,the precipitation phenom-ena and microstructural evolutions of Mg-6Zn-1Y-0.4Ce-0.5 Zr(wt.％)alloy processed by sliding friction treatment(SFT)were systematically studied using hardness texting,transmission electron microscopy(TEM)equipped with high-angle annular dark-field scanning(HADDF-STEM),X-ray diffraction(XRD)and XRD line broadening analysis.The microhardness of the SFT-processed(SFTed)sample initially decreases from 109.6 HV to 104.8 HV at ageing for 8 h,and then increases to the peak-ageing point of 115.4 HV at 16 h.Subsequently,it enters the over-aged period.The un-SFTed sample,as the counterpart,follows a regular ageing behavior that increases from 89.9 HV to 99.6 HV when ageing for 12 h,and then drops.A multi-mechanistic model is established to describe the strengthening due to grain refinement,disloca-tion accumulation,precipitation etc.The analysis reveals that the temperature sensitive UFG structure has an obvious grain coarsening effect,which arouses the soft phenomenon in the early ageing stage.But precipitation hardening provides an excellent hardness enhancement for overcoming the negative influ-ence and helping to reach the peak-aged point.In our microstructural observations,a lot of equilibrium ultrafine MgZn2 precipitates precipitate along dislocations because defects can provide the favorable conditions for the migration and segregation of solute atoms.     

采用温控和碘吸收池技术的发射激光稳频技术

多普勒测风激光雷达通过分析系统回波信号的多普勒频移反演出风速，为提高风场探测精度，从稳频技术方面展开研究。在稳频过程中，分别采取措施消除激光频率的长期漂移和短期抖动。针对激光频率的长期漂移，设计并研制了种子激光器温控箱，通过水浴的控温方式大大减小了激光频率的长期漂移，将激光频率稳定在±50 MHz以内；针对激光频率的短期抖动，采用以碘分子吸收池为核心器件的稳频系统，通过半导体控温方式对碘分子吸收池精确控温，控温精度达0.03 ℃，提高了稳频精度，将激光频率进一步稳定在±8 MHz以内，满足±10 MHz以内的设计精度要求。通过搭建多普勒测风激光雷达系统，对发射激光稳频装置进行系统验证，连续4组风场观测结果表明:系统探测高度为17 km，绝大部分方差在4 m/s以下，满足测风激光雷达测量指标的要求。     

Changes in the content and antioxidative activity of β-carotene and its metabolite vitamin A during gastrointestinal digestion and absorption and optimisation of HPLC-based detection

The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results.     

Transient Simulation of Hollow‐Fiber Membrane Filtration with Nonuniform Permeability Distribution

Transient simulation of filtration in hollow‐fiber membranes with nonuniform permeability distribution was conducted. The diversity of permeability distributions caused different initial flux and transmembrane pressure distributions. Manipulating the permeability distribution enables a hollow‐fiber membrane to achieve its maximum volumetric flow rate. During solid‐liquid separation, the inter‐adjustment between flux and cake distributions improved their uniformities simultaneously. The reciprocal of the volumetric flow rate of the membranes all increased linearly with water production. Severely nonuniform permeability distribution caused low water production. The numerical results could be applicable to account for the non‐ideal performance of industrial hollow‐fiber membrane modules.     

钢化玻璃白雾成因及解决方法

采用显微镜分析钢化白雾缺陷发现,钢化白雾是玻璃表面形成的凹坑,凹坑数量和大小不能量化白雾,且钢化白雾的表面形貌与进炉方向无关.针对白雾缺陷进行详细分析,给出具体的解决方法.     

Electrostatic-lenses position-sensitive TOF MCP detector for beam diagnostics and new scheme for mass measurements at HIAF

A foil–microchannel plate(MCP) detector,which uses electrostatic lenses and possesses both good position and timing resolutions, has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China. Characterized by low energy loss and good performances of timing and position measurements, it would be located at focal planes in fragment separator HFRS for position monitoring, beam turning, Bρ measurement, and trajectory reconstruction. Moreover, it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(Bρ-△E-TOF) method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis. Most importantly, the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci, and position measurements at a dispersive focus of HFRS, thus making it possible to use two complementary mass measurement methods [isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(Bρ-TOF) at the beam-line HFRS] in one single experimental run.     

Gelation properties of goose liver protein recovered by isoelectric solubilisation/precipitation process

Isoelectric solubilisation/precipitation (ISP) process was applied to goose liver (GL) for protein extraction. The gelation properties of proteins extracted by acid processes (ACP, pH 2.0, 2.5 and 3.0) and alkaline processes (ALP, pH 11.0, 11.5 and 12.0) were estimated, where the unextracted ground GL was set as the control. Nearly 58.39~79.00% of GL proteins were recovered by ISP treatments. High molecular weight (100~250 kDa) proteins were found to be partially hydrolysed by ACP, while few changes in proteins occurred during ALP. As evidenced by rheological and textural measurements, ALP proteins formed gels with high elasticity and superior texture, whereas ACP proteins had inferior gelation properties. Moreover, ALP proteins were able to form a highly interconnected and homogeneous three‐dimensional microstructure. Predominantly, gels produced by 11.0 had optimal texture and the lowest cooking loss (P < 0.05). These results suggested that the ISP process (ALP) is a potential method to improve the economic value of GL.     

Research on paraffin removal and prevention by Bacillus spp. in high-salinity reservoirs

Problems in paraffin deposition occur frequently in oil exploitation. Considering the problem that some paraffin removal and prevention strains cannot grow in high-salinity reservoirs, we domesticated four salt-tolerant laboratory bacterial strains. Crude oil emulsification effect, paraffin removal rate, and paraffin prevention rate of the strains were evaluated. KB and JH-A strains exhibited good paraffin removal and prevention effects, with paraffin removal rates of 51.82% and 81.56%; and 51.82% and 80.90%, respectively. Gas chromatography mass spectrometry analysis of paraffin components before and after biodegradation was performed on KB and JH-A strains. Results showed that relative contents of n-alkanes between C15–C23 and C27–C30 evidently decreased, indicating their good biodegradation. This technique provides a new method for practical application of paraffin removal and prevention in high-salinity reservoirs.     

解纤预处理对烟梗浆料以及基片性能的影响

在解纤电流80、100、120 A的条件下分别对烟梗浆料进行轻度、中度和重度解纤，研究了在烟草薄片生产中的解纤预处理对烟梗浆料性能及基片松厚度和匀度的影响。结果表明，解纤预处理可以提高浆料的打浆性能，但解纤程度过低或者过度，都不利于纤维长度和粗度的保持。适度的解纤预处理可显著降低后续打浆过程段数，节约能耗。解纤预处理后的浆料打浆段数宜保持在二段到三段。在二段打浆后，随着解纤预处理程度的加深，烟梗基片的匀度系数从336.1降低到277.8，匀度提升了17.35%；同时基片的松厚度从2.15 cm³/g降低到1.91 cm³/g，减少了11.16%。为满足再造烟叶匀度和松厚度的要求，需采用中度解纤预处理。