First stereoselective total synthesis of triumfettamide

The first total synthesis of triumfettamide (1) is described. The asymmetric syntheses of two highly functionalized units—α-hydroxylated C17 monounsaturated fatty acid unit (2) and C26 phytosphingosine (3) have been accomplished involving Sharpless asymmetric dihydroxylation, Sharpless kinetic resolution, regioselective epoxide opening, regioselective DIBAL-H reduction of acetal, Wittig olefination as the key steps. Finally N-acylation of phytosphingosine 3 with (2R,6Z)-2-hydroxy-6-heptadecenoic acid 2 followed by DDQ deprotection of PMB, provided target compound 1.     

Improved Dermal and Transdermal Delivery of Curcumin with SmartFilms and Nanocrystals

Poor aqueous solubility of active compounds is a major issue in today’s drug delivery. In this study the smartFilm-technology was exploited to improve the dermal penetration efficacy of a poorly soluble active compound (curcumin). Results were compared to the dermal penetration efficacy of curcumin from curcumin bulk suspensions and nanocrystals, respectively. The smartFilms enabled an effective dermal and transdermal penetration of curcumin, whereas curcumin bulk- and nanosuspensions were less efficient when the curcumin content was similar to the curcumin content in the smartFilms. Interestingly, it was found that increasing numbers of curcumin particles within the suspensions increased the passive dermal penetration of curcumin. The effect is caused by an aqueous meniscus that is created between particle and skin if the dispersion medium evaporates. The connecting liquid meniscus causes a local swelling of the stratum corneum and maintains a high local concentration gradient between drug particles and skin. Thus, leading to a high local passive dermal penetration of curcumin. The findings suggest a new dermal penetration mechanism for active compounds from nano-particulate drug delivery systems, which can be the base for the development of topical drug products with improved penetration efficacy in the future.     

砂土串囊式充气锚杆承载力的研究

在砂土地层中,串囊式充气锚杆的研究还比较少,其承载特性及受力机理尚不明确.本文基于莫尔-库仑模型和Vesic圆孔扩张理论法,分别对圆柱体、球体、组合体、椭球体假设下的串囊式充气锚杆的扩大段进行计算分析.并将计算结果与试验得到的实测值进行对比.结果表明:四种形状假设中椭球体的形状假设理论值与实测值的误差最小,仅为8.35...     

Segments and Hilbert schemes of points

Using results obtained from a study of homogeneous ideals sharing the same initial ideal with respect to some term order, we prove the singularity of the point corresponding to a segment ideal with respect to a degreverse term order (as, for example, the degrevlex order) in the Hilbert scheme of points in Pⁿ. In this context, we look into the properties of several types of “segment” ideals that we define and compare. This study also leads us to focus on the connections between the shape of generators of Borel ideals and the related Hilbert polynomial, thus providing an algorithm for computing all saturated Borel ideals with a given Hilbert polynomial.     

天然气水合物热分解引起多场响应的特征时间分析

天然气水合物是我国的战略能源,而要实现商业化开采,必须首先回答如何避免引发地质灾害与环境问题。开采过程涉及传热、水合物相变、渗流、地层软化与应力重分布的多场响应,进而可能引起地层破坏,甚至大尺度塌陷、滑坡、甲烷喷发泄漏等灾害。本文针对天然气水合物热分解引起多场响应的问题,通过量纲分析得到传热、水合物相变、渗流、地层应力重分布的特征时间,进一步比较分析发现,它们的时间尺度之间相差2个数量级以上,从而提出解耦分析方法,该方法已在系列模型实验设计与理论分析中得到应用。

     

评价矿井突水危险性的关键层方法

将煤层底板至含水层间承载能力最大的一层岩层看作起阻水作用的关键岩层（简称关键层）,并把它简化为薄板,利用板的理论解确定该岩层的破断跨距,用以评价底板突水的危险性．实例分析表明,这种预测突水危险性的方法是简明有效的．     

低聚壳聚糖与角质层蛋白相互作用的体外研究

以脱脂鼠角质层和提取角蛋白为模型,利用电化学交流阻抗谱、SEM、DSC、FTIR等手段,研究了低聚壳聚糖及氨基葡萄糖与角质层蛋白之间的相互作用.结果发现,氨基葡萄糖溶液处理不影响脱脂角质层膜的阻抗,而低聚壳聚糖溶液处理却可明显降低脱脂角质层膜的阻抗,阻抗值由3.79×106Ω·cm2降至8.379×105Ω·cm2.此外,壳聚糖溶液和氨基葡萄糖溶液都可明显破坏角蛋白表面致密均匀的结构,并使得角蛋白二级结构中α-螺旋结构含量减少,同时推动角蛋白α-螺旋结构向β-折叠结构和无规则卷曲结构转变.这些结果表明低聚壳聚糖与角质层蛋白相互作用,一方面可有效降低鼠角质层结构的紧密程度,另一方面可影响角蛋白的微结构,使其结构松散并出现微细孔道,从而为药物的经皮吸收与传送疏通了通道.     

Triphasic FE Modeling of the Skin Water Barrier

A skin–air model is developed to model the water barrier function of skin. The skin model is a porous solid saturated with a monovalent salt solution. The air model is a vapor diffusion model in non-moving air. In vivo measurements of water loss from human skin under varying ambient conditions are used to validate the model.     

Influence of oleic acid on the structure of a mixture of hydrated model stratum corneum fatty acids and their soaps

The phase behaviour of a hydrated (32% (w/w) water) mixture of saturated and unsaturated fatty acids and their soaps has been examined. By progressively increasing the proportion of oleic acid, it could be shown that this unsaturated component exists partly as a separate phase within the others. The unsaturated fatty acids form an H_II phase at 25°C, whereas the saturated fatty acids form a fatty acid—soap crystal under the conditions employed. The results help to explain the role played by the fatty acids (and also cholesterol) within the lipid fraction of human stratum corneum. A feature of this study is a comparison of the results obtained by X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy.     

Possibilities for human skin characterization based on strongly reduced Raman spectroscopic information

Loss‐of‐function mutations in the gene coding for filaggrin are the single most important risk factor for development of atopic dermatitis and associated allergic rhinitis and asthma. Filaggrin is enzymatically degraded to natural moisturizing factor (NMF) in the stratum corneum (SC). In vivo Raman spectra of human skin can be used to quantify the NMF concentration in SC and thereby identify carriers of a loss‐of‐function mutation in the gene coding for filaggrin, which results in decreased NMF content. Here, we demonstrate that strongly reduced Raman spectral information is sufficient to make this differentiation. This is an important step towards development of a dedicated diagnostic device of reduced complexity, size and cost as compared to current state‐of‐the‐art Raman equipment. A genetic algorithm was used to select the spectral regions needed to classify skin based on normal or reduced NMF content in SC. Using the NMF content based on full spectral information as gold standard, only four Raman regions were required to create a linear discriminant analysis model that can differentiate between skin with low NMF and skin with normal NMF with a prediction accuracy of 93 %. Copyright © 2013 John Wiley & Sons, Ltd.