一种快速的固体核径迹图像分割方法

针对有效测量中需解决的问题,提出了一种快速的固体核径迹图像分割算法,分初始分割与粘连分离两个过程。初始分割通过数学形态学开操作快速去除背景后,迭代阈值分割法实现;粘连分离采用复合距离变换计算核心膨胀半径,一次膨胀重建单个径迹轮廓。实验结果表明,算法具有较强的抗噪能力,可有效对半径≥2μm径迹进行快速分割,准确率>90%。目前已成功运用于实际项目中。     

Crystallization and morphological features of syndiotactic polystyrene induced from glassy state

Spherulitic growth rates and microstructure of syndiotactic polystyrene (sPS) cold-crystallized isothermally at various temperatures, T_c (115–240 °C), have been investigated by small-angle light scattering (SALS), optical microscopy and transmission electron microscopy. The derived activation energy for sPS chain mobility at the crystal growing front is 5.4 kJ/mol, which is relatively lower than that of isotactic polystyrene, 6.5 kJ/mol. In addition, the Hv scattering invariant (Q_Hv) measured by SALS on the crystallized sPS samples displays a pronounced minimum at 150 °C. Despite a wide range of T_c used, however, the sample crystallinity estimated by Fourier transformation infrared spectroscopy remains unchanged. Prior to crystallization, the correlation length derived from the Vv patterns on the basis of Debye–Bueche model is ca. 1.13 μm regardless of T_c used. Interconnected domains with a width of ca. 1.8±0.5 μm are readily observed in all the crystallized samples under phase contrast microscopy and the phase-separated structure is conserved within sPS spherulites whose diameters are increased with increasing T_c.

Based on the above facts, we conclude that the presence of a Q_Hv minimum is ascribed to the resultant events of the two competitive transitions i.e. liquid–solid crystallization, and liquid–liquid demixing resulting from the spinodal decomposition (SD). At lower T_c, the unstable SD transition overwhelms the crystallization. Despite the low chain mobility, the coarsening process driven by the interfacial energies has reached a certain level before crystalline nucleation takes place. At higher T_c, on the other hand, cold crystallization becomes the dominant process due to the enhanced chain mobility, leading to the suppression of ongoing SD coarsening process. At an intermediate T_c range, comparable competition of the phase separation and crystallization prohibits the development of ordered symmetry within spherulites, giving the presence of Q_Hv minimum.     

发酵液的组成对纳滤分离谷氨酰胺的影响

研究了谷氨酰胺发酵液中盐离子对纳滤分离提取谷氨酰铵的作用，系统地考察了操作温度和发酵液组成对纳滤分离透过特性的影响，确定了纳滤分离时发酵液最佳稀释倍数和操作温度. 结果表明，二价阳离子通过改变膜面电荷密度对谷氨酸的透过特性产生很大影响，使其截留率降低了8%. 发酵液中较高浓度的(NH4)2SO4使谷氨酸和谷氨酰胺的截留率和透过通量明显降低，但较高浓度的NH4Cl影响较小，这体现了纳滤膜对不同离子排斥力的差异. 当发酵液稀释至谷氨酰胺浓度为1%，pH调至7时，发酵液中的其它盐离子和残糖因浓度较低而对纳滤分离影响不显著.     

Impact of H+ ion irradiation on Matrimid®. I. Evolution in chemical structure

Ion beam irradiation can be used to modify the structure and gas transport properties of glassy polymers. This is the first of two studies that focus on the impact of H⁺ ion irradiation on the structure and permeation properties of the polyimide Matrimid®. Specifically, the evolution in chemical structure after H⁺ irradiation over a range of fluences was analyzed using FTIR spectroscopy and dissolution studies. Although H⁺ ion irradiation at very low ion fluences induced little modification in the chemical structure, irradiation at relatively high ion fluences resulted in crosslinking of the irradiated films. The branched structure of the aliphatic methyl (CH₃) was the most sensitive to the H⁺ ion irradiation. The para‐disubstituted aromatic ring showed the strongest resistance toward ion irradiation and required fairly high doses to induce degradation. Two potential crosslinking mechanisms related to the degradation of the aliphatic methyl and the benzophenone carbonyl were presented. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2010–2019, 2003     

Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

乳状液膜法分离二元氨基酸的研究

定义了乳状液膜法分离氨基酸的分离系数，并以苯丙氨酸(Phe)／天冬氧酸(Asp)作为研究对象，探讨了影响分离系数的主要因素。研究结果表明：用稳态条件下液膜体系中两种氨基酸的传质通量之比定义两种氨基酸的分离系数，能够较全面反映两种氨基酸及液膜体系所具有的特性以及影响分离系数的复杂因素，为改善分离效果提供理论指导。对于采用酸性萃取剂为载体的液膜体系来说，pH值是影响两种氨基酸分离系数的主要因素，而载体浓度对分离系数的影响程度相对较小。     

Continuous Oxygen Ion Transfer Medium as a Catalyst for High Selective Oxidative Dehydrogenation of Ethane

An oxygen permeable mixed ion and electron conducting membrane (OPMIECM) was used as an oxygen transfer medium as well as a catalyst for the oxidative dehydrogenation of ethane to produce ethylene. O^2- species transported through the membrane reacted with ethane to produce ethylene before it recombined to gaseous O², so that the deep oxidation of the products was greatly suppressed. As a result, 80% selectivity of ethylene at 84% ethane conversion was achieved, whereas 53.7% ethylene selectivity was obtained using a conventional fixed-bed reactor under the same reaction conditions with the same catalyst at 800 °C. A 100 h continuous operation of this process was carried out and the result indicates the feasibility for practical applications.     

Phenolic compounds from vacuum pyrolysis of wood wastes

Various softwood and hardwood bark residues, primary sludges and softwood sawdust residues were processed by vacuum pyrolysis in a laboratory scale batch reactor. The pyrolysis oil, water, charcoal, and gas were recovered and analyzed. The pyrolysis oils were analyzed in details for their content in phenolic compounds after derivatization to their acetyl derivatives. The influence of temperature, heating rate, feedstock bed thickness, particle size and feedstock water pretreatment on the yield of phenols was investigated. The highest yield of phenols was obtained when hardwood bark was soaked in water for 48 hours and pyrolyzed at a temperature of 450°C and a heating rate of 10°C/min. Pyrolysis performance was evaluated in terms of total phenolic yield and composition.     

多组分氯盐体系镁锂分离规律初探

以Na₂CO₃为沉淀剂,初步研究了多组分氯盐混合体系（0.6 mol MgCl₂+1.1 mol LiCl+3.2 mol NaCl）中选择性沉镁的工艺规律。结果表明：在25~80 ℃,总C与总Mg物质的量比[n（C_T）/n（Mg_T）]为 0.8~1.1时,25 ℃形成针状MgCO₃·3H₂O,40 ℃以上形成Mg₅（CO₃）₄（OH）₂·4H₂O不规则片状团聚微球,其中40~50 ℃形成的片状物较为分散且粒径较小,导致固液分离困难。40 ℃时沉镁率最低。温度越高,Li₂CO₃越易形成,沉锂率越大。n（C_T）/n（Mg_T）越大沉镁率和沉锂率越高。室温（25 ℃）、n（C_T）/n（Mg_T）=1.0时,沉镁率达98%以上,且沉锂率<0.1%,镁锂分离效果最好。     

螺旋藻泡载分离法采收的实验室研究

在一种斜臂泡沫分离装置上，较为详细地研究了泡沫塔构造、起泡剂Tween 20浓度、载气流率、pH值和乙醇浓度等因素对螺旋藻泡载采收性能的影响. 结果表明，斜臂泡沫塔可明显改善藻细胞的泡载性能, 当Tween 20浓度为100 mg/L、载气流率为30 L/h及pH=11、乙醇浓度为1%(j)时，泡载采收过程的分离因子R和浓缩倍数a可分别达到5.04~6.52和2.74~4.31.