新鲜芫荽关键性香气成分的鉴定与分析

采用溶剂辅助风味蒸发法(SAFE),结合气相色谱-质谱联机(GC-MS),通过双柱对新鲜芫荽中的挥发性成分进行了鉴定,并通过谱库检索和保留指数比对,共计从新鲜芫荽中鉴定出化合物87种,其中烃类28种,醛类20种,醇类22种,酸类4种,酯类7种,酮类3种,杂环及其他类3种。通过芳香萃取物稀释分析法(AEDA),结合气相色谱-嗅闻技术(GC-O)对新鲜芫荽进行了分析,共鉴定出21种活性香气成分,其中关键性香气成分有5种[香气稀释因子(FD)≥81],分别是反-2-十二烯醛、反-2-十三烯醛、反-2-十四烯醛、3-甲硫基丙醛、反-2-癸烯醛。     

云南新鲜松露和干制松露挥发性风味成分的对比分析

采用顶空固相微萃取(HS-SPME)法萃取云南新鲜采摘黑松露和真空冷冻干燥黑松露中的挥发性成分,利用气相色谱-质谱联用仪(GC-MS)和气相色谱-火焰光度检测器(GC-FPD)对挥发性成分和含硫物质进行鉴定。结果表明,新鲜黑松露和干制松露中分别鉴定出30种和83种挥发性风味物质,8种和19种含硫化合物。1-辛烯-3-醇、对甲酚甲醚、3-甲基丁醛、二烯丙基二硫醚和二甲基硫醚在新鲜松露中的含量较高;对甲酚甲醚、己酸、右旋柠檬烯、二甲基砜、烯丙基甲基三硫醚在干制松露中含量较高。气相色谱-嗅闻(GC-O)结合香气活力值(OAV)发现,新鲜松露中二烯丙基二硫醚、二甲基硫醚、1-辛烯-3-酮、3-甲基丁醛对香气贡献较大;干制松露中双(2-甲基-3-呋喃基)二硫醚、丙位壬内酯、己酸、1-辛烯-3-酮对伞花烃贡献较大。     

苦荞提取物的关键香气成分分析

采用固相微萃取(SPME)结合气相色谱-质谱联用技术(GC-MS)分析苦荞提取物中的挥发性成分;同时采用气相色谱-嗅闻仪(GC-O)结合香气提取稀释分析(AEDA)确定其香气活性成分,通过对香气活性成分定量并计算其香气活性值(OAV)最终确定苦荞提取物的关键性香气成分。结果显示,SPME-GC-MS在苦荞提取物中共鉴定出92种挥发性成分,包括酯类28种、醛类7种、醇类9种、酮类7种、酸类6种、烯烃8种、烷烃20种、其他类7种;经GC-O嗅闻仪共鉴定出17种香气活性化合物,定量结果显示,苯甲醇(8637.40μg/kg),苯乙醛(3150.47μg/kg)、D-柠檬烯(3080.00μg/kg)含量较高;结合稀释因子(FD)和香气活性值(OAV)推测,苯甲醛(FD=81,OAV=5)、二甲基三硫(FD=243,OAV=48)、苯甲醇(FD=81,OAV=9)、苯乙醛(FD=729,OAV=787)、丙二酸二乙酯(FD=81,OAV=1.2)5种物质对苦荞提取物的风味贡献最大,是苦荞提取物的关键香气成分。     

陈皮的挥发性香气分析

为了深入探究陈皮的挥发性香气成分,采用溶剂辅助风味蒸发法（SAFE）提取陈皮中的挥发性成分,利用气相色谱-质谱联用仪（GC-MS）和气相色谱-嗅闻联用技术（GC-O）对陈皮和九制陈皮中的挥发性风味物质进行鉴定,结果共鉴定出93挥发性成分,46种香气活性物质。为了确定关键香气物质,采用香气提取物稀释分析法（AEDA）对两种陈皮的香气活性成分作进一步分析,结果显示：萜烯类、醇类和醛类化合物是主要的香气活性物质,其中柠檬烯、月桂烯是两者共有的关键香气成分。此外,1,4-二甲基-4-乙酰基-1-环己烯、橙花醇、香茅醛、肉豆蔻醛和α-甜橙醛是陈皮中的关键香气成分;香兰素、香芹酚、紫苏醇、芳樟醇、香芹酮和β-紫罗酮是九制陈皮中关键香气成分。通过对两种陈皮的关键性风味物质进行对比分析,确定出两种陈皮中对风味贡献较大的香气化合物及其差异组分,从而为陈皮类产品的开发提供理论支撑。     

新鲜大蒜与炸蒜油挥发性风味物质的对比分析

采用溶剂辅助风味蒸发(SAFE)方法结合气相色谱-质谱联用仪(GC-MS)对新鲜大蒜和炸蒜油的挥发性风味成分进行分析,分别定性、定量出39种和62种挥发物质。新鲜大蒜与炸蒜油的挥发性风味物质的差异主要体现在杂环类、醚类和醛类化合物。利用气相色谱-嗅闻-质谱联用仪(GC-O-MS)和气味活性值(OAV)发现:由于炸蒜油中的3-乙烯基-4H-1,2-二噻烯(新鲜大蒜98.366 ng/g,炸蒜油8.665 ng/g),2-乙烯基-4H-1,3-二噻烯(新鲜大蒜293.530 ng/g,炸蒜油18.522 ng/g),1,2-二硫杂-3-环戊烯(新鲜大蒜6.177 ng/g,炸蒜油0.050 ng/g)和二烯丙基二硫醚(新鲜大蒜18.024 ng/g,炸蒜油5.633 ng/g)含量相较于新鲜大蒜中的含量下降,导致蒜辛辣味、生蒜味减弱,而反,反-2,4-癸二烯醛(0.112 ng/g)的存在为炸蒜油提供了油炸味。     

AEDA/GC-MS分析新鲜芫荽香气成分

采用溶剂辅助风味蒸发法（SAFE）结合气相色谱-质谱联机（GC-MS）,通过双柱对新鲜芫荽中的挥发性成分进行鉴定,并通过谱库检索和保留指数比对,共计从新鲜芫荽中鉴定出化合物87种,其中烃类28种,醛类20种,醇类22种,酸类4种,酯类7种,酮类3种,杂环及其他类3种。通过香气提取物稀释分析法 (AEDA) 结合气相色谱-嗅闻技术（GC-O）对新鲜芫荽进行分析,共鉴定出21种活性香气成分,其中关键香气的物质有5种 (FD≥81),分别是反-2-十二烯醛、反-2-十三烯醛、反-2-十四烯醛、3-甲硫基丙醛、反-2-癸烯醛。     

SPME-GC-MS分析榴莲果肉中的挥发性成分

为了研究榴莲果肉中的挥发性香气成分,采用两种固相微萃取纤维提取了榴莲果肉中的挥发性成分,并利用气相色谱-质谱联用技术对所得挥发性成分进行了分离与鉴定。采用保留指数和质谱进行定性,共鉴定出60种挥发性成分,其中酯类26种,含硫化合物12种,醇类7种,烃类7种,醛类3种,酸类2种、含氮化合物2种和酚类1种;采用面积归一化法确定了它们相对含量,相对含量较高的是2-甲基丁酸乙酯、丙酸乙酯、1-十四醇、乙酸乙酯、丁酸乙酯、反-2-丁烯酸乙酯、二乙基二硫醚、2-甲基丁酸丙酯、十四醛、乙硫醇。从鉴定出的挥发性成分的香气特征可知,榴莲的香气主要是由酯类化合物和含硫化合物赋予的,其中大多数酯类化合物是脂肪酸乙酯,含硫化合物中硫醇和硫醚的含量相对较高。     

五指毛桃香气挥发性成分分析

本研究的目的是分析五指毛桃香气中挥发性物质的主要化学成分。方法是采用静态顶空进样技术,对五指毛桃的香气挥发性成分进行采集,结合气相色谱-质谱联用仪对这些成分进行检测。然后,结合美国国家标准与技术局化学数据库(NIST2014)对检测结果进行检索,得出五指毛桃的香气挥发性成分主要包括醛类、酯类、烯烃、烷烃、醇类和酸类,其中醛类、酯类和烯烃类是构成香气成分的主要物质。结论:利用静态顶空技术可以成功鉴定五指毛桃香气挥发性物质的主要成分,体现了该技术应用范围广泛且实用性强,同时也为五指毛桃香气挥发性成分的研究提供了一种新方法。     

炒甘草浸膏挥发性成分分析

采用同时蒸馏方法萃取炒甘草浸膏中的挥发性成分,并用气相色谱-质谱联用技术进行分析鉴定,鉴定出28种化学成分,应用峰面积归一化法确定了各成分的相对质量分数。炒甘草浸膏挥发性香气成分主要包括糠醛(18.44%)、5-甲基呋喃醛(14.52%)、2-乙酰基呋喃(13.37%)、棕榈酸甲酯(9.62%)、棕榈酸(9.06%)、糠醇(8.05%)、亚油酸乙酯(4.77%)、亚油酸(2.79%)等。     

鱼香肉丝挥发性风味成分的分离与鉴定

采用顶空固相微萃取(SPME)法和同时蒸馏萃取(SDE)法提取鱼香肉丝中的挥发性风味成分,利用气相色谱-质谱联用技术对挥发性风味成分进行分离鉴定。结果表明,经过GC-MS分析,共鉴定出93种挥发性成分,包括烃类20种、醛类20种、酮类7种、酸类2种、酯类9种、醇类16种、醚类2种、酚类5种、含硫含氮及其他杂环化合物12种。其中,醛类、酯类和含硫含氮及其他杂环化合物可能对"鱼香"风味的形成有着重要的影响。     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution

Shrinkage reducing admixtures (SRA) have been developed to combat shrinkage cracking in concrete elements. While SRA has been shown to have significant benefits in reducing the magnitude of drying and autogenous shrinkage, it has been reported that SRA may cause a negative side effect as it reduces the rate of cement hydration and strength development in concrete. To examine the influence of SRA on cement hydration, this study explores the interactions between SRA and cement paste's pore solution. It is described that SRA is mainly composed of amphiphilic (i.e., surfactant) molecules that when added to an aqueous solution, accumulate at the solution-air interface and can significantly reduce the interfacial tension. However, these surfactants can also self-aggregate in the bulk solution (i.e., micellation) and this may limit the surface tension reduction capacity of SRA. In synthetic pore solutions, SRA is observed to form an oil-water-surfactant emulsion that may or may not be stable. Specifically, at concentrations above a critical threshold, the mixture of SRA and pore fluid is unstable and can separate into two distinct phases (an SRA-rich phase and an SRA-dilute phase). Further, chemical analysis of extracted pore solutions shows that addition of SRA to the mixing water depresses the dissolution of alkalis in the pore fluid. This results in a pore fluid with lower alkalinity which causes a reduction in the rate of cement hydration. This may explain why concrete containing SRA shows a delayed setting and a slower strength development.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

2-(2'-咪唑偶氮)萘酚-4-磺酸的合成及其分析性质的研究

合成了新显色剂咪唑偶氮－２－萘酚－４－磺酸（ＩＡＮ－４Ｓ）,研究了试剂的离解常数及其与金属离子的显色反应。     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

Comparison between surface and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete

The effectiveness of bulk hydrophobic treatment against corrosion of galvanized steel reinforcement in concrete specimens with w/c = 0.45 and w/c = 0.75 was compared with that of surface treatment, even in the presence of cracks 0.5 and 1 mm wide in the concrete cover. In this case surface hydrophobic treatments were applied both before and after cracking as a preventive and a restorative method against reinforced concrete deterioration, respectively. The obtained results in terms of water absorption, electrochemical measurements, chlorides penetration, and visual observations carried out on reinforced concrete specimens during the exposure to wet–dry cycles in 10% NaCl solution showed that bulk hydrophobization is the most effective treatment in improving the corrosion resistance of galvanized steel reinforcements in concrete also in the presence of cracks. Surface hydrophobization is very effective just in the first few exposure cycles to the aggressive environment and when used as a restorative method which is able to cancel the deleterious effect of cracks only 0.5 mm wide.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.