基于面元素重排的三维网格模型数据隐藏算法

目的 为了解决目前三维数据隐藏算法不能兼顾无失真和盲提取的问题，提出一种新的完全无失真的三维网格模型数据隐藏盲算法。方法 首先使用混沌逻辑映射选择嵌入与提取模式，保证数据的安全性。然后利用面元素重排，完全不会造成三维模型失真的性质，通过不同嵌入模式规则对三角面元素进行重排，以嵌入秘密数据。接收端则可根据相应的提取模式规则提取秘密数据。结果 仿真结果与分析表明，该算法不会对三维模型造成任何失真，嵌入容量为每顶点2比特，且能抵抗仿射变换攻击、噪声攻击和平滑攻击等。结论 这种三维数据隐藏盲算法无失真，容量大、安全性高、鲁棒性强，适用于三维载体不容修改的情形，如军事、医学、秘密通信和版权保护等。     

Cocaine Induces Cytoskeletal Changes in Cardiac Myocytes: Implications for Cardiac Morphology

Cocaine is one of the most widely abused illicit drugs worldwide and has long been recognised as an agent of cardiac dysfunction in numerous cases of drug overdose. Cocaine has previously been shown to up-regulate cytoskeletal rearrangements and morphological changes in numerous tissues; however, previous literature observes such changes primarily in clinical case reports and addiction studies. An investigation into the fundamental cytoskeletal parameters of migration, adhesion and proliferation were studied to determine the cytoskeletal and cytotoxic basis of cocaine in cardiac cells. Treatment of cardiac myocytes with cocaine increased cell migration and adhesion (p < 0.05), with no effect on cell proliferation, except with higher doses eliciting (1–10 μg/mL) its diminution and increase in cell death. Cocaine downregulated phosphorylation of cofilin, decreased expression of adhesion modulators (integrin-β3) and increased expression of ezirin within three hours of 1 μg/mL treatments. These functional responses were associated with changes in cellular morphology, including alterations in membrane stability and a stellate-like phenotype with less compaction between cells. Higher dose treatments of cocaine (5–10 μg/mL) were associated with significant cardiomyocyte cell death (p < 0.05) and loss of cellular architecture. These results highlight the importance of cocaine in mediating cardiomyocyte function and cytotoxicity associated with the possible loss of intercellular contacts required to maintain normal cell viability, with implications for cardiotoxicity relating to hypertrophy and fibrogenesis.     

Repurposing the Pummerer Rearrangement: Determination of Methionine Sulfoxides in Peptides

The reversible oxidation of methionine residues in proteins has emerged as a biologically important post-translational modification. However, detection and quantitation of methionine sulfoxide in proteins is difficult. Our aim is to develop a method for specifically derivatizing methionine sulfoxide residues. We report a Pummerer rearrangement of methionine sulfoxide treated sequentially with trimethylsilyl chloride and then 2-mercaptoimidazole or pyridine-2-thiol to produce a dithioacetal product. This derivative is stable to standard mass spectrometry conditions, and its formation identified oxidized methionine residues. The scope and requirements of dithioacetal formation are reported for methionine sulfoxide and model substrates. The reaction intermediates have been investigated by computational techniques and by ¹³C NMR spectroscopy. These provide evidence for an α-chlorinated intermediate. The derivatization allows for detection and quantitation of methionine sulfoxide in proteins by mass spectrometry and potentially by immunochemical methods.     

Fabrication of fine-grained α/β Si3N4 by Hot Pressing Flowing Sintering at 1550 °C

In this paper, Hot Pressing Flowing Sintering (HPFS) was successfully applied to the consolidation of silicon nitride ceramics at low sintering temperature. Fine-grained α/β-Si₃N₄ with high density was fabricated by HPFS at 1550 °C. The low temperature densification process was based on the hot pressing flow enhanced particle rearrangement mechanism. The shear stress which generated in the flowing process helped enhance the particle rearrangement with the lubrication of the liquid phase, which lead to collapse of the pores. The densification process was finished with minimum grain growth. Meanwhile, the rod-like β-Si₃N₄ nuclei was textured during the flowing process. The (101)/(210) ratio of β-Si₃N₄ was 0.09 on the plane perpendicular to the hot-pressing direction. The Vickers hardness and flexural strength of the sintered sample was 19.59 ± 0.36 GPa and 1022 ± 138 MPa, respectively.     

Trudinger-Moser不等式的两种证明方法

Trudinger-Moser不等式在研究带有临界指数增长非线性项的偏微分方程解的存在性问题上有着重要的应用.在径向空间中利用施瓦兹对称重排，基于单位分解的技巧取截断函数是证明Trudinger-Moser不等式的两种主要方法.     

发烟硫酸条件下环己酮肟贝克曼重排工艺进展

综述了环己酮肟在发烟硫酸条件下液相重排生成己内酰胺的相关新工艺、新设备及新技术,并对其进行了概括和分析.     

Formation of Furan Fatty Alkyl Esters from their Bis‐Epoxide Fatty Esters

Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2‐ethylhexanol, benzyl alcohol, in the presence of Brønsted acid catalyst, were investigated. Products, not reported in prior studies of similar reactions, were found. These were furan fatty acid alkyl esters (FFE, mixture of alkyl 8‐(5‐hexyl‐2‐furyl) octanoate and alkyl 9‐(5‐pentyl‐2‐furyl)nonanoate) which were unambiguously identified by means of GC–MS and two‐dimensional NMR. Evidence suggests that the FFE are formed by an acid‐catalyzed rearrangement of the epoxidized linoleates. The FFE were formed in presence of all four alcohols tested and in the presence of either sulfuric acid or Amberlyst 15 catalyst. Yields of up to 13 %, as quantified by GC and NMR spectroscopies, were observed.     

5-氨基-1,4-苯并二恶烷盐酸盐的合成

以2,3-二羟基苯甲酸为原料,经酚羟基烷基化保护、羧酸叠氮化、Curtius重排、水解成盐四步反应以35%的总收率合成了5-氨基-1,4-苯并二恶烷盐酸盐,其结构经1H-NMR确认。由于合理的反应溶剂选择和反应温度控制,减少了副反应的发生、简化了工艺操作、降低了分离难度、提高了收率和产品纯度,使得该路线适合于工业化生产。     

Ring‐Opening/Expansion Rearrangement of Cycloprop[2,3]inden‐1‐ols Catalyzed by p‐Toluenesulfonic Acid

A divergent approach to generate either 1‐hydroxymethylindenes (which could then be converted to benzofulvenes through a dehydration reaction) or naphthalenes by the rearrangement of cycloprop[2,3]inden‐1‐ols is reported. The effect of the cyclopropyl ring substitution pattern on ring‐opening/expansion rearrangements of the substrates was systemically studied.