Papers by Keyword: Confocal Laser Scanning Microscopy

Abstract: The frame compliance is calibrated by experimental and calculation methods for an instrumented indentation equipment. The indentation depth and contact diameter with single cycle test is determined by confocal laser scanning microscopy directly. The alternative method is to calculate the contact depth and the contact radius from the load-depth curves. The observed and calculated frame compliances are obtained respectively according to EN ISO 14577-4 Annex Methods 2.

Abstract: In-Situ direct observation was used to observe the liquation in an Inconel 617. High-Temperature Confocal Laser Scanning Microscopy (HT-CLSM) was used to observe the phenomena. Experiment was perform at 1330 °C with heating rate 5 °C/s. Results showed that the liquidation started at 1319.2 °C (268.08 seconds) in which liquid formed around precipitate. At 1330.5 °C (272.05 seconds) the liquid film wet and penetrated along grain boundaries. Then after 277.05 seconds, sufficient liquid film formed and moved freely on the surface of the specimen across grain boundaries. After cooling to room temperature, the test specimen was analyzed for local chemical composition gradient of precipitates and liquid film. Precipitate morphology changed from polygonal shape to round shape using SEM and EPMA. The results from this observation could be used to explain liquation mechanism occurred in Inconel 617 during heating.

Abstract: Acquisition of lipids mainly in a form of triacylglycerol from microalgae is a potential way for biofuels production. Many unicellular microalgae make little triacylglycerol under favorable growth condition, but accumulate large amounts of it under environmental stress conditions (e.g., nutrient depletion, high light). In this paper, the green microalgae Chlamydomonas reinhardtii BAFJ5 was used as a model to study production of lipid bodies (LBs) which are important lipid storage organelles, particularly under stress. We discovered LBs accumulated dramatically when cells were grown in nitrogen-deplete medium. Using fluorescent microscopy and confocal laser scanning microscopy, intracellular LBs can be successfully visualized. The number and size of LBs were also quantified.

Abstract: In this paper, two kinds of stamps (squares (a×a)) separated by spacing b, the values of a and b were varied from 2.5 µm to 50 µm), i.e. positive and negative stamps, were prepared. The stamps inked with the rhodamine-labeled bovine serum albumin (BSA) were then microcontacted with the aldehyde-functionalized titanium surfaces. Water contact angle and X-ray photoelectron spectrum (XPS) indicated that BSA can be covalently immobilized on aldehyde modified titanium surface by microcontact printing. The experimental results of CLSM showed that the patterns with resolution from 2.5 µm to 50 µm were obtained successfully. Both positive stamp and negative stamp were deformed when the value of a was less than or equal to 5 µm, which resulted in replication errors. Furthermore, the larger spacing (50 µm) resulted in stamp collapse when the value a of the positive stamp was less than or equal to 10 µm, leading to whole fluorescence on substrates.

Abstract: One of the most important tasks of the manufacturing engineering of our accelerated world is giving suitable answer to the ever growing demand on miniaturization arising on every field of the industry. Our institute has been carried out theoretical and experimental research work on micro machining since 10 years. Micro machining can be defined as formation of structures smaller than 1 mm. Our previous research activity focused primarily on micro milling process carried out by carbide end mill. Milling offers the most various machining method among the chip removal processes. Investigation of formation of micro structures by electrical discharge machining (EDM) is a perfect continuance of the research work. A process similar to micro milling can be realized by the lateral moving of the miniature cylindrical electrode of an EDM machine, just the physical principle of material removing is different. This paper introduces the latest results of our research work, including

Abstract: The purpose of this study was to evaluate the bone interface response to different surface using bone remodeling rate (BRR) under cyclic loading. The tibiae of 10 New Zealand white rabbits were used. Each tibia of rabbits received 2 implants, one with anodic oxidation surface and the other with machined surface. Dynamic loading, a cyclic load of 100 N with 100 cycles was applied for 2 weeks. All implants were divided into 4 groups according to surface treatment and loading; (1) machined surface, unloaded, (2) anodic oxidation surface, unloaded, (3) machined surface, loaded, and (4) anodic oxidation surface, loaded. To determine the rate of bone formation, a series of fluorochrome bone labeling materials (tetracycline, alizarin red, and calcein green) were administrated intramuscularly at 10, 11, 12 weeks. To study the formation time of new bone, ground sections were examined under confocal laser scanning microscopy. Resonance frequency analysis (RFA) values were measured at the time of first surgery, second surgery and sacrifice. From this study, it was concluded that implants with anodic oxidation surface had higher value than machined surface on RFA measurement and anodic oxidation surface has more resistance to loading than machined surface.

Abstract: Collagen is the most used naturally occurring scaffold material. It’s a structural protein ubiquitous among mammalian. The ability of collagen type I to host different cell phenotype in vitro and its low antigenecity in vivo are well known. However, the principal drawback of collagenbased materials consists in their low mechanical properties. For vascular tissue engineering this represents a major limit, as the aim is to mimic the structure of a native vessel, which is known to be resistant and viscoelastic. Moreover, vascular cells are known to be susceptible in vivo to reorganize the matrix in which they proliferate. Therefore, the aim of this project is to study the micro structural organization of collagen-based scaffolds, and to assess the interactions between collagen and smooth muscle cells during regeneration. This knowledge will then allow the development of appropriate strategies to tailor the microstructure of the scaffold and its properties. Smooth muscle cells (SMCs) were selected to study the interactions between cells and matrix during the proliferation. Atomic Force Microscopy (AFM) in dry state in tapping mode and Confocal Laser Scanning Microscopy (CLSM) in reflection mode were used to investigate the microstructure of the scaffold. For the former technique cells were seeded on top of the collagen gel after jellification, while for the latter, cells were embedded into the collagen gel and stained with Rhodamine. The contact points between matrix and cells were investigated, as well as the capacity of vascular cells to induce a structural reorganization of collagen fibrils in the scaffold.

Abstract: Anaerobically digested sludge was seeded in a mesophilic UASB reactor and the sludge was monitored for seven months to better understand the start-up process of the reactor. The reactor was fed with synthetic wastewater containing glucose. As the COD loading rate increased stepwise (from 1 to 4 g COD l-1 d-1), the methane production rate increased. COD removal efficiency was maintained to be greater than 90% after day 36. Maximum value of the methane production rate (6.0-6.5 l d-1) was achieved from day 152 and remained stable afterward. Although the reactor showed steady performance in terms of COD removal efficiency and methane production under constant hydraulic retention time (HRT) or COD loading rates, physicochemical and microbial properties of UASB sludge kept changing during the initial 5 months of operation. Specific methanogenic activity was initially negligible but increased until day 150, and then remained constant (0.72 + 0.11 g CH4-COD g-1 VSS d-1) afterward. Sludge volume index showed that the settling ability of UASB sludge gradually improved until it reached a plateau in day 120. Improved settling-ability could provide a basis for keeping bed height constant despite shortened HRT. The mean diameter of the UASB sludge gradually increased until approximately day 150 and maintained a maximum value (0.48 mm) afterward. Confocal laser scanning microscopy revealed F420-based autofluorescence of physical and optical sections of UASB sludge, suggesting the locations of autofluorescent methanogens in the UASB sludge during the start-up period. During the initial operation of the reactor, autofluorescence showed random and uneven distribution inside the sludge. However, autofluorescence appeared as an inner layer near the edge of the sludge with time, suggesting more abundant or active methanogens in this layer. The highest autofluorescence was observed in the range of 20 to 28 µm depth from the surface of granule as determined by optical slicing of UASB sludge. The results obtained in this study provide insight into UASB sludge development that involves dynamic changes in physicochemical and microbial aspects during the start-up period.