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《Ceramics International》2021,47(23):33223-33231
The effects of pH of the reaction solution and the concentration of phosphoric acid on the crystal growth behavior of LaPO4 crystallites were investigated and the mechanical properties of rare-earth phosphates were compared. As a result, the concentration of phosphoric acid of 10% was beneficial to the crystal growth of LaPO4 nanocrystalline. When the pH value of the reaction solution was 2, the size of LaPO4 crystallites increased gradually with the increasing reaction temperature, and the smallest crystallite size of 43.27 nm was obtained after heat-treatment at 1000 °C. Simultaneously, the activation energy for crystal growth of LaPO4 nanocrystalline was relatively lower (26.82 kJ mol−1). With the decreasing radii of rare-earth ions, the hardness, Young's modulus and fracture toughness of the bulk rare-earth phosphates exhibited a reduced tendency, resulted from the increase of porosity under the same preparation process. 相似文献
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《水科学与水工程》2020,13(1):65-73
This study investigated the removal of hexavalent chromium(Cr(VI)) in aqueous solutions using pomelo peel(PP) and FeCl_3-modified pomelo peel(FPP) as novel biomass adsorbents.Batch adsorption experiments were performed to evaluate the effects of pH,time,temperature,initial concentration,and adsorbent dose on Cr(VI) removal by PP and FPP.The results show that the maximum adsorption capacity of Cr(VI)was 21.55 mg/g for FPP and 0.57 mg/g for PP at a pH of 2.0 and a temperature of 40℃.The surface shape,microstructure,and chemical composition of FPP were analyzed with scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),and energy dispersive spectroscopy(EDS),and compared with those of PP.The results show that the adsorption performance of FPP was much better than that of PP,indicating that FPP can be an alternative high-efficiency adsorbent for Cr(VI) removal. 相似文献
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Along with the progress in nanoscience, a variety of advanced functional nanomaterials were constructed to develop effective and innovative analytical techniques for food safety surveillance. In this review, we summarized the advanced analytical methods that have been developed based upon advanced functional nanomaterials, including plasmonic nanomaterial-based colorimetric methods, fluorescent nanomaterial-based fluorescent methods, advanced functional material-based molecular imprinting technology, advanced functional material-based chromatographic methods, plasmonic nanomaterial-based surface enhanced Raman scattering technology, and advanced functional material-based electrochemical methods. This review provides a progressive roadmap for further development of portable, rapid, and in situ detection technology to promote food safety surveillance from bench to market and eventually reduce the gap between research in the laboratory and industrial applications. 相似文献
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Hydrogen storage properties of Mg98.5Gd1Zn0.5 and Mg98.5Gd0.5Y0.5Zn0.5 alloys containing LPSO phases
《International Journal of Hydrogen Energy》2021,46(65):32949-32961
In this work, the as-cast Mg-rich Mg98.5Gd1Zn0.5 and Mg98.5Gd0.5Y0.5Zn0.5 alloys are prepared by the semi-continuous casting method, and their hydrogen storage performance and catalytic mechanisms are investigated by experimental and first-principles calculations approaches. The results show that the LPSO phases decompose and in-situ form the RE(Gd/Y)Hx(x = 2,3) nano-hydrides upon hydrogenation. These nano-hydrides not only serve as the in-situ catalysts to promote the hydrogen ab/desorption of Mg matrix, but also present the pinning effect to inhibit the growth of Mg/MgH2 grains during hydrogenation and dehydrogenation. Comparatively, the two alloys exhibit the similar hydrogen absorption kinetics, while the hydrogen desorption kinetics of Mg98.5Gd1Zn0.5 is superior to that of Mg98.5Gd0.5Y0.5Zn0.5. The first-principles calculations reveal that the GdH2 and YH2 hydrides exhibit different catalytic effects on weakening the bond strength of H–H within H2 and Mg–H within MgH2, which interprets well the differences in the hydrogen ab/desorption kinetics between Mg98.5Gd1Zn0.5 and Mg98.5Gd0.5Y0.5Zn0.5 alloys. 相似文献
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Jie Luo Chenbo Jiang Liang Zhao Ming Zhang Fang Wang Erna Sun Fazheng Ren 《Journal of dairy science》2018,101(11):9725-9735
3-Methylbutanal is one of the primary substances that contribute to the nutty flavor in cheese. Lactococcus strains have been shown to have higher aminotransferase and α-keto acid decarboxylase activities compared with other microbes, indicating that they might form a higher amount of 3-methylbutanal by decarboxylation. Several dairy lactococcal strains have been successfully applied as adjunct cultures to increase the 3-methylbutanal content of cheese. Moreover, compared with dairy cultures, the nondairy lactococci are generally metabolically more diverse with more active AA-converting enzymes. Therefore, it might be appropriate to use nondairy lactococcal strains as adjunct cultures to enrich the 3-methylbutanal content of cheese. This study thereby aimed to select a nondairy Lactococcus strain that is highly productive of 3-methylbutanal, identify its biosynthetic pathway, and apply it to cheese manufacture. Twenty wild nondairy lactococci isolated from 5 kinds of Chinese traditional fermented products were identified using 16S rRNA sequence analysis and were found to belong to Lactococcus lactis ssp. lactis. The nondairy strains were then screened in vitro for their production of 3-methylbutanal and whether they met the criteria to become an adjunct culture for cheese. The L. lactis ssp. lactis F9, isolated from sour bamboo shoot, was selected because of its higher 3-methylbutanal production, suitable autolysis rate, and lower acid production. The enzymes involved in the catabolic pathway of leucine were then evaluated. Both α-keto acid decarboxylase (6.96 μmol/g per minute) and α-keto acid dehydrogenase (30.06 μmol/g per minute) activities were detected in nondairy L. lactis F9. Cheddar cheeses made with different F9 levels were ripened at 13°C and analyzed after 90 d by a combination of instrumental and sensory methods. The results showed that adding nondairy L. lactis F9 significantly increased 3-methylbutanal content and enhanced the nutty flavor of the cheese without impairing its textural properties. Thus, nondairy L. lactis F9 efficiently enhanced the biosynthesis of 3-methylbutanal in vitro and in manufactured cheese. 相似文献
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为考察不同热处理对籼米籽粒及其半干粉品质的影响,采用不同条件热处理籼米籽粒,分析米粒表观裂缝增加程度与其内部水分的关系,并进行半干法制粉(含水率为30%),测定不同热处理对大米粉微生物、破损淀粉及白度的影响。结果表明,热处理后的米粒,表观裂缝开始明显增加时米粒内部水分均小于8%;3种热处理(60℃90 min,120℃15min及180℃1min)后的大米调制粉微生物被有效抑制,且超高温短时(120℃15min,180℃1min)抑菌效果优于低温长时(60℃90min),破损淀粉、白度及糊化特性与干磨粉差异显著(P0.05),更接近湿磨粉。通过测定米粒内部水分可判断米粒表观裂缝增加的程度,且热处理大米籽粒进行半干法制粉其粉质特性与湿磨粉相当。 相似文献
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研究近红外光谱技术对食用醋品牌进行快速无损溯源。收集市场上保宁、东湖、恒顺、镇江4个品种共152份具有代表性的食用醋样品,采集它们的近红外光谱数据,对原始光谱数据进行多元散射校正(multip,licative scatter corrertion,MSC)预处理,对预处理后的光谱数据利用主成分分析法(principal component analysis,PCA)进行聚类分析,根据主成分的累计贡献率选取主成分数,然后用支持向量机(support vector machine,SVM)建立预测模型,选取合适的SVM核函数,并利用粒子群优化算法(particle swarm optimization,PSO)优化模型参数。结果表明,近红外光谱技术结合支持向量机对食用醋品牌分类正确率可达100%。 相似文献
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三种不同改性方法对甘薯渣不溶性膳食纤维改性效果的研究 总被引:1,自引:0,他引:1
该研究采用胶体磨湿法粉碎法、超声波辅助酸法、纤维素酶法3种方法处理甘薯渣不溶性膳食纤维(insoluble dietary fiber,IDF),比较改性前后IDF粒径分布、微观形态,并测定分析其理化性质。结果表明,与未改性甘薯渣IDF相比,3种改性方法改性之后,甘薯渣IDF的粒径、分散指数显著降低(P<0.01),持油力、持水力存在显著差异(P<0.01),吸附亚硝酸盐及胆固醇能力都有不同程度的提升。整体而言,这3种改性方法对甘薯渣IDF改性都有效果,并且胶体磨湿法粉碎法改性对甘薯渣IDF的持油力、持水力、吸附亚硝酸盐及胆固醇能力效果最好。甘薯渣改性的IDF可作为功能性成分应用于多种食品。 相似文献