西安供暖前后细颗粒物化学特征及棕碳吸光特性

2015年11月1 - 30日在西安用大流量采样器每12 h进行1次细颗粒物(PM_(2.5))样品采集,分析供暖前后PM_(2.5)中有机碳(OC),元素碳(EC),水溶性有机碳(WSOC)与无机离子的浓度和棕碳吸光度的变化特征,探讨供暖对城市大气气溶胶理化特性的影响。结果显示:供暖前(11月1 - 15日)与供暖后(11月16 - 30日)PM_(2.5)浓度分别为127 &plusmn; 59 &mu;g &middot; m~(-3)和164 &plusmn; 126 &mu;g &middot; m~(-3),供暖后比供暖前增加了30%,其中K~+、Cl~-、和分别增加了30%、70%、40%和38%。洁净期(PM_(2.5) &lt; 75 &mu;g &middot; m~(-3))与灰霾期(PM_(2.5) &gt;150 &mu;g &middot; m~(-3))对比显示:洁净期Na~+、Ca~(2+)、Mg~(2+)的相对含量均大于灰霾期,这是由于灰霾发生时不利的静稳天气条件(风速&lt;1 m &middot; s~(-1))使得粉尘粒子干沉降效应增加所致。洁净期[NO_3~-]/[SO_4~(2-)]质量比均大于1而灰霾期均小于1,这是因为灰霾期高湿条件有利于二氧化硫液相转化为硫酸盐所致。供暖前灰霾期[NO_3~-]/[SO_4~(2-)]比值要高于供暖后的灰霾期,这与西安及其周边地区燃煤取暖排放二氧化硫增加有关。供暖前后棕碳的质量吸收效率(MAE)值均是洁净期大于灰霾期,表明:与非灰霾天相比,当灰霾发生时不利的静稳天气条件使得细粒子在大气中长时间存留,延长其二次氧化反应时间,使得棕碳中含C = C不饱和键的吸光性物质被深度氧化,从而降低其吸光性能。</p

黑果枸杞籽油品质及体外抗氧化活性Quality and in vitro antioxidant activity of Lycium ruthenicum seed oil

为挖掘黑果枸杞籽油的潜在开发利用价值，采用石油醚浸提法提取黑果枸杞籽油，对黑果枸杞籽油的理化性质进行测定，分析其脂肪酸组成及含量，并测定其对DPPH·、ABTS+·的清除能力和总还原能力。结果表明：黑果枸杞籽油碘值（I）为(84.0±0.2) g/100 g，皂化值（KOH）为(130.1±0.3) mg/g，过氧化值为(0.42±0.03) g/100 g，酸值（KOH）为(8.4 ±0.2) mg/g，需进一步精炼；黑果枸杞籽油主要包括亚油酸（68.31%）、油酸（17.76%）、棕榈酸（5.37%）、γ-亚麻酸（3.73%）、硬脂酸（2.58%）等9种脂肪酸；黑果枸杞籽油对DPPH·清除率的IC50为0.587 mg/mL，3.2 mg/mL黑果枸杞籽油的ABTS+·清除率为57.50%，且其具备一定的Fe3+还原能力。因此，黑果枸杞籽油富含不饱和脂肪酸，体外抗氧化活性良好，具有开发的价值和潜力。 In order to tap the potential development and utilization value of Lycium ruthenicum seed oil, Lycium ruthenicum seed oil was extracted by petroleum ether, and its physicochemical properties, fatty acid composition and content , DPPH· and ABTS+· scavenging power, and total reducing power were analyzed . The results showed that the iodine value, saponification value, peroxide value and acid value of Lycium ruthenicum seed oil were (84.0±0.2)gI/100 g, (130.1±0.3)mgKOH/g, (0.42±0.03) g/100 g, and (8.4±0.2) mgKOH/g, respectively, and it needed to be further refined. Lycium ruthenicum seed oil contained 9 kinds of fatty acids, such as linoleic acid (68.31%), oleic acid (17.76%), palmitic acid (5.37%), γ-linolenic acid (3.73%), and stearic acid (2.58%) and so on. The IC50 of Lycium ruthenicum seed oil for DPPH·scavenging rate was 0.587 mg/mL, the ABTS+· scavenging rate of 3.2 mg/mL Lycium ruthenicum seed oil was 57.50%，and it had a certain Fe3+ reduction power. Lycium ruthenicum seed oil is rich in unsaturated fatty acids, and it has good in vitro antioxidant activity, so it has development value and potential