传统炭烤羊腿特征挥发性风味物质分析

运用固相微萃取结合气相色谱-质谱技术,测定3 种具有代表性的传统炭烤工艺下生产烤羊腿产品中的挥发性风味物质。结果表明：共检测到八大类69 种挥发性风味物质;以风味活性值为依据,筛选出17 种特征挥发性风味物质,其中,3 种不同炭烤方式烤羊腿中共有的特征物质为正己醛、庚醛、2-正戊基呋喃、正辛醛、壬醛、癸醛、反-2-壬烯醛、十二醛、反,反-2,4-癸二烯醛、十一醛、1-辛烯-3-醇、正庚醇、正辛醇、反-2-辛烯-1-醇和2-甲基苯酚;明确传统炭烤羊腿的风味特征为淡脂香、青草香、烤肉味、发酵味和烟熏香味。     

食用香料风险评估方法与应用

食用香料的风险评估方法与其他食品添加剂相比有一定的特殊性,毒理学关注阈值法是香料评估的主要方法。应用毒理学关注阈值法进行香料评估时,同样要求对人类的暴露水平进行正确估计,目前常用的香料暴露评估方法有源自调查的最大摄入量法、单份暴露技术、双份暴露技术等。本文将介绍食用香料的风险评估方法。     

抗菌防臭纺织品相关基础性问题

 诸多文献报道了抗菌防臭纺织品的制备及抗菌测试技术,但是消费者对其必要性、有效性及安全性还是疑问重重。本文讨论和分析了与抗菌防臭纺织品相关的四个基础性问题的研究进展, 具体包括人体皮肤菌群的微生态环境、人体异味产生及其味道分子、皮肤细菌和人体异味及纺织品间的相关性、以及抗菌纺织品对皮肤正常菌群的影响。人体表面皮肤菌群具有自身的防御机制,一般条件下不需要使用抗菌制品来预防细菌感染。通过抗菌制品可抑制部分异味,而对于皮肤上细菌已产生的异味要通过消臭加工消除。纺织品上的细菌移生和对人体异味的保留性和纤维种类密切相关。非持续的长期使用抗菌纺织品不会对皮肤正常菌群造成破坏。人体皮肤细菌、人体异味及纺织品的相互作用是相当复杂的,还有待继续深入研究     

N-1,3,5-二氢二噻嗪基乙酸、2-（N-1,3,5-二氢二噻嗪基）丙酸和3-苯基-2-（N-1,3,5-二氢二噻嗪基）丙酸的合成及其香气特征

0℃下,在氨基酸的氢氧化钾溶液中,依次加入38%的甲醛、2mol/L的硫氢化钠溶液,充分搅拌反应,然后让其自然升至室温过夜,分别合成N-1,3,5-二氢二噻嗪基乙酸、2-（N-1,3,5-二氢二噻嗪基）丙酸和3-苯基-2-（N-1,3,5-二氢二噻嗪基）丙酸,收率分别为77.2%、73.7%和67.1%。这些化合物结构都通过IR、MS和1HNMR测试技术进行了表征,并对其进行了初步香味评价。结果表明,它们都具有硫磺样、热带水果样香味特征,阈值为18.5～30.7mg·kg-1。     

Optical properties of transparent polycrystalline ruby (Cr:Al2O3) fabricated by high-pressure spark plasma sintering

Doped transparent ceramics with high optical quality can serve as materials for photonic applications such as laser gain media. In that regard, transparent polycrystalline alumina has potential for high-power applications due to its excellent physical and chemical properties, combined with unique doping possibilities. However, optical birefringence of Al₂O₃ crystals make achieving sufficiently high optical transmittance a processing challenge. In the present study, we demonstrated fabrication of highly transparent 0.5 at.% Cr:Al₂O₃ ceramics by high-pressure spark plasma sintering (HPSPS). The optical properties of these polycrystalline ruby ceramics were analyzed in order to assess possible laser operation (at 694.3 nm). The obtained ceramics exhibit high in-line transmittance (～72.5 % at 700 nm), equivalent to a scattering coefficient of 2.15 cm^?1, and characteristic ruby photoluminescence. The theoretically estimated lasing threshold and percentage of absorbed pump power indicate that such ruby ceramic lasers could operate at reasonable thresholds of 80?225 mW with short lengths of 0.5?5 mm. Thus, HPSPS is a promising method for producing laser-quality doped transparent ceramics for compact laser systems.     

Random-valued impulse noise removal using adaptive dual threshold median filter

Noise detection and its removal is very important in the image processing. Detection of noise is very crucial and significant in random valued impulse noise because it does not hamper the image pixels uniformly. This paper presents a novel and unique concept of adaptive dual threshold for the detection of random valued impulse noise along with simple median filter at noise removal stage. Simulation results shows that an efficient noise detection leads to a superior quality of de-noised image as compared to existing adaptive threshold based image de-noising techniques. Proposed threshold computation is based on averaging of pixel values of window which enhances the PSNR of our system as compared to existing median filter based image de-noising methods.     

Low threshold voltage,highly stable electroforming-free threshold switching characteristics in VOx films-based device

Threshold switching (TS) devices have evolved as one of the most promising elements in memory circuit due to their important significance in suppressing crosstalk current in the crisscross array structure. However, the issue of high threshold voltage (V_th) and low stability still restricts their potential applications. Herein, the vanadium oxide (VO_x) films deposited by the pulsed laser deposition (PLD) method are adopted as the switching layer to construct the TS devices. The TS devices with Pt/VO_x/Pt/PI structure exhibit non-polar, electroforming-free, and volatile TS characteristics with an ultralow V_th (+0.48 V/−0.48 V). Besides that, the TS devices also demonstrates high stability, without obviously performance degradations after 350 cycles of endurance measurements. Additionally, the transition mechanism is mainly attributed to the synergistic effect of metal-insulator transition of VO₂ and oxygen vacancies. Furthermore, the nonvolatile bipolar resistance switching behaviors can be obtained by changing oxygen pressure during the deposition process for switching films. This work demonstrates that vanadium oxide film is a good candidate as switching layer for applications in the TS devices and opens an avenue for future electronics.     

Influence of expertise on semantic categorization of wine odors

Aromatic characterization is a key element of enhancing one’s knowledge of wine. While several studies have investigated the importance of wine expertise in the ability to perform odor-related sensory tasks, little attention has been paid to the influence of expertise on the semantic categorization of wine odors. To bridge this gap, this study aimed to explore the influence of a subject’s expertise on the semantic representation of wine odors by means of a free sorting task. For this purpose, 156 subjects were recruited. Their level of expertise was measured using a questionnaire and the data analysis revealed four clusters of subjects with a gradual level of expertise. Subjects also performed a sorting task on 96 odor terms. From the number and the size of odor groups formed, as well as the additive tree representation and the consensus partition between the terms for each expertise level, we observed that all subjects, regardless of their experience, had largely the same semantic categorization of wine-odor attributes, which was mainly shaped by the sources of the odorants. It appeared that level of wine expertise played a minor role in creating the semantic representation of wine odors, affecting mainly the knowledge of specialized terms.