表面涂覆含氟羟基磷灰石和缺钙羟基磷灰石的镁合金体外降解行为(英文)

通过电化学沉积方法,在生物降解镁合金表面覆盖含氟羟基磷灰石(FHA)涂层和缺钙羟基磷灰石(CDHA)涂层。采用X射线衍射、傅立叶变换红外光谱、透射电子显微镜、扫描电子显微镜和能量色散X射线光谱研究涂层特性。结果表明:涂覆纳米FHA涂层的样品具有垂直于样品表面的纳米针状结构,比涂覆CDHA涂层样品的结构更致密和更均匀。纳米FHA涂层比纳米CDHA涂层具有更小的晶粒尺寸,分别为65 nm和95 nm。然而,CDHA涂层比FHA涂层更厚,厚度分别为19μm和15μm。通过极化、浸泡和析氢实验研究的腐蚀行为表明:纳米FHA涂层和纳米CDHA涂层显著降低腐蚀速率并引起钝化。纳米FHA和纳米CDHA涂层可以加速骨状磷灰石层的形成,相比未覆盖的镁合金可以显著减少溶出速率。纳米FHA涂层能对镁合金提供有效的防护并具有更高的腐蚀性能。因此,覆盖纳米FHA涂层的镁合金在整形外科领域具有良好的应用前景。     

Application of ferrous sulfate alleviates negative impact of cadmium in rice (<i>Oryza sativa</i> L.)

Soil contamination with toxic heavy metals [such as cadmium (Cd)] is becoming a serious global problem dueto rapid development of social economy. Iron (Fe), being an important element, has been found effective in enhancingplant tolerance against biotic and abiotic stresses. The present study investigated the extent to which different levels ofFerrous sulphate (FeSO₄) modulated the Cd tolerance of rice (Oryza sativa L.), when maintained in artificially Cdspiked regimes. A pot experiment was conducted under controlled conditions for 146 days, by using natural soil,mixed with different levels of CdCl₂ [0 (no Cd), 0.5 and 1 mg/kg] together with the exogenous application of FeSO₄at [0 (no Fe), 1.5 and 3 mg/kg] levels to monitor different growth, gaseous exchange characteristics, oxidative stress,antioxidative responses, minerals accumulation, organic acid exudation patterns of O. sativa. Our results depicted thataddition of Cd to the soil significantly (P < 0.05) decreased plant growth and biomass, gaseous exchange parameters,mineral uptake by the plants, sugars (soluble, reducing, and non-reducing sugar) and altered the ultrastructure ofchloroplasts, plastoglobuli, mitochondria, and many other cellular organelles in Cd-stressed O. sativa compared tothose plants which were grown without the addition of Cd in the soil. However, Cd toxicity boosted the production ofreactive oxygen species (ROS) by increasing the contents of malondialdehyde (MDA), which is the indication ofoxidative stress in O. sativa and was also manifested by hydrogen peroxide (H₂O₂) contents and electrolyte leakage tothe membrane bounded organelles. Although, activities of various antioxidative enzymes like superoxidase dismutase(SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) and non-enzymatic antioxidants likephenolics, flavonoid, ascorbic acid, anthocyanin and proline contents increased up to a Cd level of 0.5 mg/kg in thesoil but were significantly diminished at the highest Cd level of 1 mg/kg in the soil compared to those plants whichwere grown without the addition of Cd in the soil. The negative impacts of Cd injury were reduced by the applicationof FeSO₄ which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes, minerals uptake together with diminished exudation of organic acids as well as oxidative stress indicators in roots andshoots of O. sativa by decreasing Cd retention in different plant parts. These results shed light on the effectiveness ofFeSO₄ in improving the growth and upregulation of antioxidant enzyme activities of O. sativa in response to Cdstress. However, further studies at field levels are required to explore the mechanisms of FeSO₄-mediated reduction ofthe toxicity of not only Cd, but possibly also other heavy metals in plants.     

微酸性电解水凝胶对天麻鲜切片贮藏品质的影响

目的 研究微酸性电解水(slightly acidic electrolyzed water,SAEW)凝胶对天麻鲜切片贮藏品质的影响。方法 以不同有效氯浓度、凝胶浓度和处理时间为自变量,样品表面菌落存活数量级为响应值,利用响应面优化法得出最佳组合并对天麻鲜切片进行(4±1)℃贮藏实验,分别在贮藏0、2、4、6、8、10 d内测定天麻鲜切片的表面菌落总数、色差、天麻多糖含量、质量损失率。以无菌水处理作对照,分析SAEW凝胶对天麻鲜切片贮藏品质的影响。结果 天麻鲜切片在0～10d的贮藏过程中,处理组菌落总数为2.06logCFU/g、色差值变化为5.89、质量损失率为1.24%、天麻多糖含量减少2.06%。对照组菌落总数为3.72 log CFU/g、色差值变化为10.01、质量损失率为3.24%、天麻多糖含量减少5.45%。结论 SAEW凝胶在控制天麻鲜切片表面微生物危害和延缓品质衰减方面有一定潜力,相关结果有助于天麻鲜切片保鲜技术理论的完善。     

WATER ADDUCTS ON ACETYLACETONE,DIETHYLDITHIOCARBAMATE AND DITHIZONE CHELATES IN WATER AND CHLOROFORM

The number of water molecules associated with several metal chelates in water and then after being extracted into chloroform has been determined. A relationship between the number of water molecule adducts in the aqueous phase and the charge to volume ratio was determined for the acetylacetone system and an empirical equation developed.     

DETECTION AND DISCRIMINATION OF ENTEROBACTER SAKAZAKII (CRONOBACTER SPP.) BY MID-INFRARED SPECTROSCOPY AND MULTIVARIATE STATISTICAL ANALYSES

Enterobacter sakazakii can cause rare but life-threatening diseases such as meningitis in infants and neonates. Fourier transform infrared (FT-IR) spectroscopy was used to detect and discriminate between eight E. sakazakii strains, two Enterobacter cloacae strains, three Escherichia coli strains and two Klebsiella pneumoniae strains. FT-IR vibrational combination bands reflect subtle compositional differences in the cell membranes of E. sakazakii strains, especially in the region between 1,200 and 900 cm ^{− 1} which contains absorption bands from carbohydrates. Two multivariate statistical analyses including principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA) were used for data analysis. E. sakazakii strains were clearly distinguishable from the other strains by PCA. Based upon SIMCA analysis, 90% of E. sakazakii, 88% of E. cloacae, 91% of E. coli and 91% of K. pneumoniae samples were correctly classified, suggesting that this technique could be used to detect E. sakazakii strains rapidly and accurately.

PRACTICAL APPLICATIONS

Fourier transform infrared (FT-IR) coupled with multivariate statistical analyses can be used to detect, discriminate and identify Enterobacter sakazakii strains that have been implicated in food safety incidents caused by contaminated infant formula. Compared with traditional microbiological plating methods, this new approach of using FT-IR could be an alternative means for rapid and accurate detection of bacterial samples that are important in agricultural, food and medical areas.     

WATER ADDUCTS ON SEVERAL BEIIZOHYDROXAHIC ACID AND 8-HYDROXYQUINOLINE CHELATES IN AQUEOUS AID ORGANIC SOLVENTS

ABSTRACT

Water adducts on the vanadium (V) and Mn(II) chelates of Denzohydroxamic acid in water saturated with various organic solvents were measured. A correlation of the % extraction of the chelate with the hydrodynamic volume was observed. The number of water adducts remaining after the iron (III), vanadium (V), uranium (VI), and copper (II) 8-hydroxyquinoline chelates were extracted into chloroform was determined.     

Preparation and characterization of asymmetric ultrafiltration membrane for effective recovery of proteases from surimi wash water

The wash water generated from the surimi processing industry contains a large amount of proteases which are widely used in the food and biotechnology industries. Asymmetric polysulfone and polyethersulfone ultrafiltration (PSf-UF and PES-UF) membranes with three different polymer concentrations were screened for their abilities to recover proteases from surimi wash water. In-house fabricated membranes were prepared via a simple dry/wet phase inversion technique and were characterized in terms of permeability coefficient, membrane morphology and molecular weight cut-off (MWCO). The ability of the UF membranes to remove commercial proteases was tested at various pressures (up to 10 bars). The membrane with the best performance, 15 wt-% PSf-UF, was further tested with actual surimi wash water. The effect of the pH of the feed solution (4 to 8) in the pre-treatment stage was also evaluated to recover the highest amount of proteases. The highest retention of protease was 96% with a flux of 25.6 L/(m²·h) which was achieved with the 15 wt-% PSf-UF membrane.     

Endogenous levels of somatostatin, C-peptide and insulin in acute pancreatitis

The authors compared in seven patients with acute pancreatitis the levels of endogenous somatostatin, insulin and C-peptide to assess their mutual correlation and relation to the development of the disease and serum amalyse levels. The results were compared with values recorded in 11 healthy volunteers. The levels of endogenous somatostatin were in patients with acute pancreatitis significantly higher (p < 0.05) than in the control group. The authors found an inverse relationship between the somatostatin and amylase level (correlation coefficient 0.75). They did not observe a significant correlation between somatostatin and insulin levels nor between somatostatin and C-peptide levels. The elevated somatostatin level may be due to the counteregulatory reaction during secretion, stimulated by endogenous or exogenous factors (cholecystokinin, alcohol, food).     

Parameter optimization of microwave sintering porous Ti-23%Nb shape memory alloys for biomedical applications

Porous Ti-23%Nb (mole fraction) shape memory alloys (SMAs) were prepared successfully by microwave sintering with excellent outer finishing (without space holder). The effects of microwave-sintering on the microstructure, phase composition, phase-transformation temperature, mechanical properties and shape-memory effect were investigated. The results show that the density and size of porosity vary based on the sintering time and temperature, in which the smallest size and the most uniform pore shape are exhibited with Ti-23%Nb SMA after being sintered at 900 °C for 30 min. The microstructure of porous Ti-Nb SMA consists of predominant α″, α, and β phases in needle-like and plate-like morphologies, and their volume fractions vary based on the sintering time and temperature. The β phase represents the largest phase due to the higher content of β stabilizer element with little intensities of α and α″ phases. The highest ultimate strength and its strain are indicated for the sample sintered at 900 °C for 30 min, while the best superelasticity is for the sample sintered at 1200 °C for 30 min. The low-elastic modulus enables these alloys to avoid the problem of “stress shielding”. Therefore, microwave heating can be employed to sinter Ti-alloys for biomedical applications and improve the mechanical properties of these alloys.     

微波烧结生物医用多孔Ti-23%Nb形状记忆合金的参数优化（英文）

采用微波烧结法成功制备多孔Ti-23%Nb(摩尔分数)形状记忆合金(SMAs)(不含造孔剂)。研究微波烧结对合金显微组织、相组成、相变温度、力学性能和形状记忆效应的影响。结果表明,烧结时间和温度对合金密度和孔隙度大小的影响较大,在900℃下烧结30 min的Ti-23%Nb SMA具有最小的孔径和最均匀的孔形状。多孔Ti-Nb SMA的显微组织主要含有针状和片状的α"、α和β相,且体积分数随烧结时间和温度不同而变化。由于β相稳定元素的含量较高,因此β相含量最多,而α和α"相的含量较少。900℃烧结30 min的样品呈现最优的极限强度和应变,而1200℃烧结30 min的样品则具有最高的超弹性。这些合金的弹性模量较低,可以避免"应力屏蔽"效应。因此,微波加热可以应用于烧结生物医用Ti合金并提高其力学性能。