Reynolds number-dependent permeability of wastewater sludge flocs

Most theoretical models assume constant permeability of wastewater sludge floc. This work shows that, at creeping flow limit with small intrafloc Reynolds number, the permeability of floc can not only be affected by floc structure, but also by the external flow condition. The three-dimensional structure of flocs using the fluorescence in situ hybridization (FISH) and the confocal laser scanning microscope (CLSM) was firstly probed. Then, the volumetric grid models for sludge flocs were constructed. We noted that the floc permeability could keep unchanged, increased, or decreased at increased Reynolds number (Re). Flow redistribution among channels of various sizes contributes to the noted Re-dependent permeability of flocs.     

Ovule Development and in Planta Transformation of Paphiopedilum Maudiae by Agrobacterium-Mediated Ovary-Injection

In this paper, the development of the Paphiopedilum Maudiae embryo sac at different developmental stages after pollination was assessed by confocal laser scanning microscopy. The mature seeds of P. Maudiae consisted of an exopleura and a spherical embryo, but without an endosperm, while the inner integument cells were absorbed by the developing embryo. The P. Maudiae embryo sac exhibited an Allium type of development. The time taken for the embryo to develop to a mature sac was 45-50 days after pollination (DAP) and most mature embryo sacs had completed fertilization and formed zygotes by about 50–54 DAP. In planta transformation was achieved by injection of the ovaries by Agrobacterium, resulting in 38 protocorms or seedlings after several rounds of hygromycin selection, corresponding to 2, 7, 5, 1, 3, 4, 9, and 7 plantlets from Agrobacterium-mediated ovary-injection at 30, 35, 42, 43, 45, 48, 50, and 53 DAP, respectively. Transformation efficiency was highest at 50 DAP (2.54%), followed by 2.48% at 53 DAP and 2.45% at 48 DAP. Four randomly selected hygromycin-resistant plants were GUS-positive after PCR analysis. Semi-quantitative PCR and quantitative real-time PCR analysis revealed the expression of the hpt gene in the leaves of eight hygromycin-resistant seedlings following Agrobacterium-mediated ovary-injection at 30, 35, 42, 43, 45, 48, 50, and 53 DAP, while hpt expression was not detected in the control. The best time to inject P. Maudiae ovaries in planta with Agrobacterium is 48-53 DAP, which corresponds to the period of fertilization. This protocol represents the first genetic transformation protocol for any Paphiopedilum species and will allow for expanded molecular breeding programs to introduce useful and interesting genes that can expand its ornamental and horticulturally important characteristics.     

Can scanning near‐field optical microscopy be compared with confocal laser scanning microscopy? A preliminary study on α‐sarcoglycan and β1D‐integrin in human skeletal muscle

The dystrophin–glycoprotein complex and the vinculin–talin–integrin system constitute, together a protein machinery, called costameres. The dystrophin–glycoprotein complex contains, among other proteins, also dystrophin and the sarcoglycans subcomplex, proteins playing a key role in the pathogenesis of many muscular dystrophies and linking the cytoplasmic myofibrillar contractile elements to the signal transducing molecules of the extracellular matrix, also providing structural support to the sarcolemma. The vinculin–talin–integrin system connects some components of the extracellular matrix with intermediate filaments of desmin, forming transverse bridges between Z and M lines. In our previous reports we always studied these systems by confocal laser scanning microscopy (CLSM). In this paper we report on the first applications of optical near‐field fluorescence microscopy to the spatial localization of α‐sarcoglycan and β1D‐integrin in human skeletal muscle fibres in order to better compare and test the images obtained with conventional CLSM and with scanning near‐field optical microscopy (SNOM). In addition, the analysis of the surface morphology, and the comparison with the fluorescence map is put forward and analyzed for the first time on human muscle fibres. In aperture‐SNOM the sample is excited through the nanometre‐scale aperture produced at the apex of an optical fibre after tapering and subsequent metal coating. The acquisition of the topography map, simultaneously to the optical signal, by SNOM, permits to exactly overlap the fluorescence images obtained from the two consecutive scans needed for the double localization. Besides, the differences between the topography and the optical spatial patterns permit to assess the absence of artefacts in the fluorescence maps. Although the SNOM represented a good method of analysis, this technique remains a complementary method to the CLSM and it can be accepted in order to confirm the hypothesis advanced by CLSM.     

Practical limitations of superresolution imaging due to conventional sample preparation revealed by a direct comparison of CLSM,SIM and dSTORM

We evaluate the suitability of conventional sample preparation and labelling methods for two superresolution techniques, structured illumination microscopy and direct stochastic optical reconstruction microscopy, by a comparison to established confocal laser scanning microscopy. We show that SIM is compatible with standard fixation procedures and immunofluorescence labelling protocols and improves resolution by a factor of two compared to confocal laser scanning microscopy. With direct stochastic optical reconstruction microscopy, fluorophores can theoretically be localized with much higher precision. However, in practice, with indirect immunofluorescence labelling density can be insufficient due to the bulky probes to reveal biological structures with high resolution. Fine structures like single actin fibres are in fact resolved with direct stochastic optical reconstruction microscopy when using small affinity probes, but require proper adjustment of the fixation protocol. Finally, by a direct comparison of immunofluorescent and genetic labelling with fluorescent proteins, we show that target morphology in direct stochastic optical reconstruction microscopy data sets can differ significantly depending on the labelling method and the molecular environment of the target.     

高温激光共聚焦显微镜在钢铁材料中研究进展

介绍了高温激光共聚焦显微镜的工作原理及主要功能,详细汇总了近年来高温激光共聚焦显微镜在钢铁冶金领域、材料研发领域、焊接领域的研究进展,包括钢液在高温熔融过程中夹杂物上浮、聚集、长大行为以及夹杂物聚集的动力学机制研究、相变行为等。利用高温激光共聚焦显微镜研究钢中典型珠光体、贝氏体和马氏体相变基本特征,探讨了不同尺寸粒子在高温对晶界的钉扎、溶解等行为,分析了当前应用过程中存在的主要问题,提出了相应的改进建议,并为后期高温激光共聚焦在钢铁材料领域的应用研究提供参考。     

Characterization of activated sludge flocs by confocal laser scanning microscopy and image analysis

In this study we present a new approach to determine volumes, heterogeneity factors, and compositions of the bacterial population of activated sludge flocs by 3D confocal imaging. After staining the fresh flocs with fluorescein-isothiocyanate, 75 stacks of images (containing approx. 3000 flocs) were acquired with a confocal laser scanning microscope. The self-developed macro 3D volume and surface determination for the KS 400 software package combined the images of one stack to a 3D image and calculated the real floc volume and surface. We determined heterogeneity factors like the ratio of real floc surface to the surface of a sphere with the respective volume and the fractal dimension (D(f)). According to their significant influence on floc integrity and quality, we also investigated the chemical composition of flocs and quantified their bacterial population structure by using group-specific rRNA-targeted probes for fluorescence in situ hybridization. By a settling experiment we enriched flocs with poor settling properties and determined the above-mentioned parameters. This approach revealed shifts in floc volume, heterogeneity, and bacterial and chemical composition according to the settling quality of the flocs.     

DNA molecule stretching through thermo-electrophoresis and thermal convection in a heated converging-diverging microchannel

A novel DNA molecule stretching technique is developed and tested herein. Through a heated converging-diverging microchannel, thermal convection and thermophoresis induced by regional heating are shown to significantly elongate single DNA molecules; they are visualized via a confocal laser scanning microscopy. In addition, electrophoretic stretching is also implemented to examine the hybrid effect on the conformation and dynamics of single DNA molecules. The physical properties of the DNA molecules are secured via experimental measurements.     

Proportioning cement based composites with burnt coal cinder

This paper presents an experimental investigation to advance a stepwise procedure to proportion plain and slag concrete mixes with burnt coal cinder waste as coarse aggregate. When typical strength of coarse aggregate in concrete is lower than the concrete strength required, conventional methods such as British Method, ACI and country’s standard code cannot be used directly since failure of concrete is predominantly by aggregate crushing. To analyze the data, concrete, for simplicity, is regarded as two phase composite of cement mortar matrix and coarse aggregate. With the concrete and constituent cement mortar matrix strengths and their respective volume fractions as input parameters, the typical strength of coarse aggregate in concrete is determined from linear law of mixtures. Using again the same law, the cement mortar matrix strength required for higher or at par to that of the typical aggregate strength is calculated. To arrive at water–cement ratio for matrix strength, the Generalized Abrams’ law is employed.