2-异丙基-3-羟基-3-甲基-3-吡嗪丙酸乙酯的合成及其对卷烟烟气增香的研究

以乙酰基吡嗪和异戊酸乙酯为原料,合成了2．异丙基-3-羟基-3-甲基-3-吡嗪丙酸乙酯(1)。其结构经^1H NMR和MS表征。加香评吸实验表明其对烤烟型卷烟的香气有很好的提升作用,可以掩盖杂气,余味更舒适。烟气分析结果证明,1是一种前体香料,在燃烧状况下能发生裂解反应,释放出乙酰基吡嗪。     

利用烟草高效转化功能基因体系的建立

对农杆菌介导的烟草遗传转化条件进行探索,以20 mg/L的潮霉素作为转化苗的筛选压,稀释至OD600为O.2～O.3的农杆菌对外植体浸染15 min,于添加300 mg/L头孢霉素的生根培养基中诱导生根,可稳定获得较高的阳性转化率.经PCR和PCR-Souttlern检测,阳性转基因植株达84.8%以上.通过本研究建立了一种稳定高效的功能基因烟草遗传转化体系.     

最小Higgs模型在ILC上可能的味改变物理迹象

在最小Higgs(LH)模型中, 由于引进了类矢量顶夸克T, 对弱作用流产生了新的影响. CKM矩阵从3×3变为4×3, 在树图下出现味改变中性流(FCNC). 本文研究了在国际高能直线对撞机(ILC)上能否通过e⁺e^－→tc+tc和e⁺e^－→WWν_eν_e→(tc+tc) ν_eν_e过程探测到LH模型所预言的FCNC信号.     

Tobacco alkaloids analyzed by Raman spectroscopy and DFT calculations

The tobacco alkaloids: nicotine, nornicotine, cotinine, anabasine, their protonated forms, and salts were analyzed by means of Raman spectroscopy supported by the density functional theory/B3LYP/aug‐cc‐pVDZ calculations. The analyses were performed based on Raman marker bands of neutral, monoprotonated, and diprotonated forms of tobacco alkaloids because in different surroundings various forms have been suggested to either dominate or to coexist. The form and distribution of nicotine directly in a plant and in phytopharmaceutical products were investigated by in situ Raman mapping. For the first time, the Raman optical activity spectrum of (−)‐nicotine in aqueous solution was measured and interpreted by means of the density functional theory calculations. The study provides a clear evidence that Raman spectroscopy techniques are powerful in efficient quality control and forensic and bioanalytical analyses of tobacco alkaloids. Copyright © 2012 John Wiley & Sons, Ltd.     

Neutrino mass ordering and μ-τ reflection symmetry breaking

If the neutrino mass spectrum turns out to be m_3 m_1 m_2, it may be relabeled as m_1 m_2 m_3 such that all the masses of fundamental fermions with the same electrical charges are in order. In this case the columns of the 3×3 lepton flavor mixing matrix U should be reordered accordingly, and the resulting pattern U may involve one or two large mixing angles in the standard parametrization or its variations. Since the Majorana neutrino mass matrix remains unchanged in such a mass relabeling, a possible μ-τ reflection symmetry is respected in this connection and its breaking effects are model-independently constrained at the 3σ level by using current experimental data.     

Whether the Research on Ethanol–Water Microstructure in Traditional Baijiu Should Be Strengthened?

Baijiu is a unique and traditional distilled liquor in China. Flavor plays a crucial rule in baijiu. Up to now, the research on the flavor of baijiu has progressed from the identification of volatile compounds to the research on key aroma compounds, but the release mechanism of these characteristic compounds is still unclear. Meanwhile, volatile compounds account for only a tiny fraction, whereas ethanol and water account for more than 98% of the content in baijiu. By summarizing the ethanol–water hydrogen bond structure in different alcoholic beverages, it was found that flavor compounds can affect the association strength of the ethanol–water hydrogen bond, and ethanol–water can also affect the interface distribution of flavor compounds. Therefore, the research on ethanol–water microstructure in baijiu is helpful to realize the simple visualization of adulteration detection, aging determination and flavor release mechanism analysis of baijiu, and further uncover the mystery of baijiu.     

Rare decays of the tau lepton at Belle

We report recent results of searches for lepton flavor violation and second class current in decays of τ leptons using the data sample collected in the Belle experiment at the KEKB electron-positron asymmetricenergy collider.     

Low-scale leptogenesis and the domain wall problem in models with discrete flavor symmetries

We propose a new mechanism for leptogenesis, which is naturally realized in models with a flavor symmetry based on the discrete group A₄$A_4$, where the symmetry breaking parameter also controls the Majorana masses for the heavy right-handed (RH) neutrinos. During the early universe, for T?TeV$T?\text{TeV}$, part of the symmetry is restored, due to finite temperature contributions, and the RH neutrinos remain massless and can be produced in thermal equilibrium even at temperatures well below the most conservative gravitino bounds. Below this temperature the phase transition occurs and they become massive, decaying out of equilibrium and producing the necessary lepton asymmetry. Unless the symmetry is broken explicitly by Planck-suppressed terms, the domain walls generated by the symmetry breaking survive till the quark–hadron phase transition, where they disappear due to a small energy splitting between the A₄$A_4$ vacua caused by the QCD anomaly.     

Separation,identification, and structural characterization of sucrose ester isomers from tobacco

Sucrose esters (SEs) are crucial tobacco smoke flavor precursors and play a significant role in tobacco's functionality. Due to their structural complexity, the separation and analysis of SEs in tobacco remain a major challenge, and massive structures of SEs have not yet been fully identified. In this study, the fractions enriched in SEs were obtained from oriental and flue-cured tobacco through a series of pretreatments, and two types of SEs (Types I and II) were distinguished by liquid chromatography-tandem mass spectrometry (LC-MSⁿ) analysis, with Type II SEs newly characterized in tobacco. Five groups of main SEs were further purified using preparative high-performance LC (HPLC) coupled to an evaporative light scattering detector, and their structures were characterized by nuclear magnetic resonance spectrometry techniques including ¹H, ¹³C, correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. By combining LC-MSⁿ and nuclear magnetic resonance spectrometry, the structures of eight SE isomers were finally proposed, of which four were newly identified. These findings further enhance the understanding of the structural diversity of SEs in tobacco, serving as a valuable reference for future research on the elucidation, synthesis, and metabolism of SEs.     

具有整体代对称性的左右对称模型中的中微子质量

本文基于具有整体U(1)代对称性的SU(2)_L×SU(2)_R×U(1)模型推导了轻子的味混合矩阵,对中微子的质量问题进行了研究.在本文的模型中,产生轻子Dirac质量的汤川耦合拉格朗日密度具有整体U(1)代对称性,所以,模型中的带电轻子质量矩阵和中微子Dirac质量矩阵是Fritzsch形式的.但是,中微子除了具有Dirac质量,一般还具有Majorana质量,在这种一般情况下, 关键词： 中微子质量 轻子味混合矩阵 左右对称模型 代对称性