Polarization of skylight in the O(2)A band: effects of aerosol properties

Motivated by several observations of the degree of linear polarization of skylight in the oxygen A (O(2)A) band that do not yet have a quantitative explanation, we analyze the influence of aerosol altitude, microphysics, and optical thickness on the degree of linear polarization of the zenith skylight in the spectral region of the O(2)A band, between 755 to 775 nm. It is shown that the degree of linear polarization inside the O(2)A band is particularly sensitive to aerosol altitude. The sensitivity is strongest for aerosols within the troposphere and depends also on their microphysical properties and optical thickness. The polarization of the O(2)A band can be larger than the polarization of the continuum, which typically occurs for strongly polarizing aerosols in an elevated layer, or smaller, which typically occurs for depolarizing aerosols or cirrus clouds in an elevated layer. We show that in the case of a single aerosol layer in the atmosphere a determination of the aerosol layer altitude may be obtained. Furthermore, we show limitations of the aerosol layer altitude determination in case of multiple aerosol layers. To perform these simulations we developed a fast method for multiple scattering radiative transfer calculations in gaseous absorption bands including polarization. The method is a combination of doubling-adding and k-binning methods. We present an error estimation of this method by comparing with accurate line-by-line radiative transfer simulations. For the Motivated by several observations of the degree of linear polarization of skylight in the oxygen A (O(2)A) band that do not yet have a quantitative explanation, we analyze the influence of aerosol altitude, microphysics, and optical thickness on the degree of linear polarization of the zenith skylight in the spectral region of the O(2)A band, between 755 to 775 nm. It is shown that the degree of linear polarization inside the O(2)A band is particularly sensitive to aerosol altitude. The sensitivity is strongest for aerosols within the troposphere and depends also on their microphysical properties and optical thickness. The polarization of the O(2)A band can be larger than the polarization of the continuum, which typically occurs for strongly polarizing aerosols in an elevated layer, or smaller, which typically occurs for depolarizing aerosols or cirrus clouds in an elevated layer. We show that in the case of a single aerosol layer in the atmosphere a determination of the aerosol layer altitude may be obtained. Furthermore, we show limitations of the aerosol layer altitude determination in case of multiple aerosol layers. To perform these simulations we developed a fast method for multiple scattering radiative transfer calculations in gaseous absorption bands including polarization. The method is a combination of doubling-adding and k-binning methods. We present an error estimation of this method by comparing with accurate line-by-line radiative transfer simulations. For the O(2)A band, the errors in the degree of linear polarization are less than 0.11% for transmitted light, and less than 0.31% for reflected light. band, the errors in the degree of linear polarization are less than 0.11% for transmitted light, and less than 0.31% for reflected light.     

一种基于厚膜工艺的高集成度FAIMS迁移管的研制

基于厚膜工艺,研制了一种集成有进样接口、气路接口、温控元件和离子源固定装置等外围功能模块的高集成度FAIMS迁移管,阐述了其结构特征和制作方法。为验证其性能,搭建了相应的FAIMS外围检测平台,以丙酮和甲苯为样品进行实验,得到了它们的FAIMS谱图,并与基于MEMS工艺的非集成FAIMS迁移管所测得的丙酮和甲苯的谱图比较,证明了高集成度迁移管在功耗、漏电流、气密性、灵敏度、分辨率和稳定性等方面的优异性能,说明高集成度迁移管适合作为小型化FAIMS独立检测系统的核心器件。     

Degradable polyester scaffolds with controlled surface chemistry combining minimal protein adsorption with specific bioactivation

Advanced biomaterials and scaffolds for tissue engineering place high demands on materials and exceed the passive biocompatibility requirements previously considered acceptable for biomedical implants. Together with degradability, the activation of specific cell–material interactions and a three-dimensional environment that mimics the extracellular matrix are core challenges and prerequisites for the organization of living cells to functional tissue. Moreover, although bioactive signalling combined with minimization of non-specific protein adsorption is an advanced modification technique for flat surfaces, it is usually not accomplished for three-dimensional fibrous scaffolds used in tissue engineering. Here, we present a one-step preparation of fully synthetic, bioactive and degradable extracellular matrix-mimetic scaffolds by electrospinning, using poly(D,L-lactide-co-glycolide) as the matrix polymer. Addition of a functional, amphiphilic macromolecule based on star-shaped poly(ethylene oxide) transforms current biomedically used degradable polyesters into hydrophilic fibres, which causes the suppression of non-specific protein adsorption on the fibres’ surface. The subsequent covalent attachment of cell-adhesion-mediating peptides to the hydrophilic fibres promotes specific bioactivation and enables adhesion of cells through exclusive recognition of the immobilized binding motifs. This approach permits synthetic materials to directly control cell behaviour, for example, resembling the binding of cells to fibronectin immobilized on collagen fibres in the extracellular matrix of connective tissue.     

ALD functionalized nanoporous gold: thermal stability, mechanical properties, and catalytic activity

Nanoporous metals have many technologically promising applications, but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only 1 nm thick oxide films can stabilize the nanoscale morphology of np-Au up to 1,000°C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO(2) ALD coatings. Our results open the door to high-temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications.     

新式筛分设备布勒公司新一代提高灵活性、卫生性和实用性的“积木式组合“平筛

平筛的工作性能,对于制粉厂的经济效益,具有十分重要的影响.平筛是小麦制粉具有关键作用的设备,它们决定制粉厂的生产效率、产品的质量及其稳定性、纯净度和清洁度.     

Cloning and disruption of the PpURA5 gene and construction of a set of integration vectors for the stable genetic modification of Pichia pastoris

A pair of degenerate primers was used for amplification and cloning of a DNA fragment containing parts of the P. pastoris URA5 and SEC65 genes. Using additional information from a partial genomic sequence of P. pastoris, we cloned and sequenced a 1.9 kb chromosomal fragment containing the complete orotate-phosphoribosyltransferase-encoding URA5 gene. A disruption cassette was constructed by replacing a small part of the open reading frame with a kanamycin-resistance gene. The P. pastoris wild-type strain NRRL Y-11430 was transformed with the disruption cassette and an ura5 auxotrophic strain was identified. To generate marker constructs that can be reused in successive transformations of a single strain, we constructed two lacZ-PpURA3-lacZ and lacZ-PpURA5-lacZ cassettes and used them to disrupt PpOCH1. The PpURA3 and PpURA5 genes in the disruptants were then successfully recycled by selecting for resistance to 5'-fluoro-orotic acid. We also assembled a set of modular plasmids that can be used for the stable genetic modification of P. pastoris via a double cross-over event. The sequence presented here has been submitted to the EMBL data library under Accession No. AY303544.     

Volumetric analysis of MRI data monitoring the treatment of polycystic kidney disease in a mouse model

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The human condition autosomal dominant polycystic kidney disease (ADPKD) is characterized by the growth of cysts in the kidneys that increase renal volume and lead to kidney failure. Mice studies are performed for treatment development monitored with imaging. The analysis of the imaging data is typically manual, which is costly and potentially biased. This paper presents a reliable and reproducible method for the automated segmentation of polycystic mouse kidneys.     

Dietary fibre fractions in cereal foods measured by a new integrated AOAC method

The reliable determination of soluble, insoluble and total dietary fibre in baked goods and cereal flours is an important issue for research, nutritional labelling and marketing. We compared total dietary fibre (TDF) contents of selected cereal based foods determined by AOAC Method 991.43 and the new AOAC Method 2009.01. Fifteen bread and bakery products were included in the study. Our results showed that TDF values of cereal products determined by AOAC Method 2009.01 were always significantly higher than those determined by AOAC Method 991.43. This was explained by the inclusion of low molecular weight soluble fibre fractions and resistant starch fractions in the TDF measurement by AOAC 2009.01. This documents that nutritional labelling of cereal products poses the challenge how to update TDF data in nutrient databases in a reasonable time with an acceptable expenditure.     

Functionalization of electrospun fibers of poly(ε-caprolactone) with star shaped NCO-poly(ethylene glycol)-<Emphasis Type="Italic">stat</Emphasis>-poly(propylene glycol) for neuronal cell guidance

Microfibers produced with electrospinning have recently been used in tissue engineering. In the development of artificial implants for nerve regeneration they are of particular interest as guidance structures for cell migration and axonal growth. Using electrospinning we produced parallel-orientated biocompatible fibers in the submicron range consisting of poly(ε-caprolactone) (PCL) and star shaped NCO-poly(ethylene glycol)-stat-poly(propylene glycol) (sPEG). Addition of the bioactive peptide sequence glycine-arginine-glycine-aspartate-serine (GRGDS) or the extracellular matrix protein fibronectin to the electrospinning solution resulted in functionalized fibers. Surface characteristics and biological properties of functionalized and non-functionalised fibers were investigated. Polymer solutions and electrospinning process parameters were varied to obtain high quality orientated fibers. A polymer mixture containing high molecular weight PCL, PCL-diol, and sPEG permitted a chemical reaction between hydroxyl groups of the diol and isocyanante groups of the sPEG. Surface analysis demonstrated that sPEG at the fiber surface minimized protein adhesion. In vitro experiments using dorsal root ganglia explants showed that the cell repellent property of pure PCL/sPEG fibers was overcome by functionalization either with GRGDS peptide or fibronectin. In this way cell migration and axonal outgrowth along fibers were significantly increased. Thus, functionalized electrospun PCL/sPEG fibers, while preventing non-specific protein adsorption, are a suitable substrate for biological and medical applications.