The effects of types of degradable polymers on porcine chondrocyte adhesion, proliferation and gene expression

Understanding how a specific biomaterial may influence chondrocyte adhesion, proliferation and gene expression is important in cartilage tissue engineering. In this study several biodegradable polymers that are commonly used in tissue engineering were evaluated with respect to their influence on chondrocyte attachment, proliferation and gene expression. Primary cultures of porcine chondrocytes were performed in films made of poly-L-lactic acid (PLLA), poly-D,L-lactic acid (PDLLA), poly-(lactide-co-glycolide) (PLGA), or polycaprolactone (PCL). Chondrocytes adhered to PDLLA or PLGA after 1-day incubation better than to PLLA or PCL. After 7 or 14 day culture, the cell numbers on PDLLA or PLGA was still higher than PLLA or PCL. The results suggested that cell attachment and growth might depend on degradation rate of biodegradable polymers. Along with the fact that PDLLA or PLGA supported expression of chondrocyte specific genes more than PLLA or PCL, the former two materials seemed to be more suitable for cartilage tissue engineering than the latter ones. Besides, we found that chondrocyte phenotype prior to seeding was important in the expression of ECM proteins.     

The generation of mono-energetic electron beams from ultrashort pulse laser-plasma interactions

The physics of the interaction of high-intensity laser pulses with underdense plasma depends not only on the interaction intensity but also on the laser pulse length. We show experimentally that as intensities are increased beyond 10(20) W cm(-2) the peak electron acceleration increases beyond that which can be produced from single stage plasma wave acceleration and it is likely that direct laser acceleration mechanisms begin to play an important role. If, alternatively, the pulse length is reduced such that it approaches the plasma period of a relativistic electron plasma wave, high-power interactions at much lower intensity enable the generation of quasi-mono-energetic beams of relativistic electrons.     

Microfluidic sequential injection analysis in a short capillary

An automated microfluidic sequential injection analysis system that efficiently manipulates sample and reagent solutions in the nanoliter range in approximately 10 s per analytical cycle is described. The system consisted of a 6-cm-long, typically 75-microm i.d., fused-silica capillary (which functioned as a sampling probe and reactor as well as a flow-through detection cell), a horizontally oriented waste reservoir that provided liquid level differences for inducing gravity-driven flows, an autosampling device holding samples and reagents with horizontally fixed slotted microvials, and a laser-induced fluorescence detection system. Sample and reagent zones were sequentially introduced via gravity-driven flow by scanning the capillary tip (functioning as the sampling probe) through the vial slots, while vials containing sample, reagent, and carrier were sequentially rotated to the probe by programmed movement of the vial holders. Sequentially injected nanoliter zones were rapidly mixed by convection and diffusion within the carrier flow, demonstrating a behavior that conformed well to the Taylor dispersion model, and zone penetration effects were characterized and optimized under Taylor's dispersion theory guidelines. For the determination of fluorescein, a high throughput of 400 h(-1) was achieved, rapidly producing calibration curves (five points) within 45 s. Owing to its adaptability to the Taylor's dispersion model, the system was used also for measuring diffusion coefficients of fluorescent species. Potentials for using the system in enzyme inhibition assays were demonstrated by a reaction involving the conversion of fluorescein digalactoside to fluorescent hydrolysates via beta-galactosidase and the inhibition of beta-galactosidase by diethylenetriaminepentaacetic acid.     

Comparisons of 239Pu inhalation doses calculated with ICRP 67 and proposed systemic models

The International Commission on Radiological Protection (ICRP) has issued an age-specific systemic biokinetic model for plutonium (Pu), which was later modified to give better agreement with measured urinary excretion data. Recently, the current ICRP systemic Pu model was improved by Leggett et al. based on recently developed data. Incorporation of 239Pu in the human body may result in significant internal radiation exposure. In the present work, the retentions in organs and tissues, the equivalent dose and effective dose from 239Pu for workers and members of the public were estimated and compared under the current ICRP and the proposed models. 239Pu contents in liver and in other soft tissue calculated with the proposed model are higher than predicted by the ICRP model, whereas bone content is lower than predicted by the ICRP model. Based on the proposed model, the inhalation equivalent dose coefficient in some organs, e.g. liver and kidneys, is increased, but there is no significant change in the effective inhalation dose coefficients of 239Pu for workers and members of the public.     

Disparity analysis of images

An algorithm for matching images of real world scenes is presented. The matching is a specification of the geometrical disparity between the images and may be used to partially reconstruct the three-dimensional structure of the scene. Sets of candidate matching points are selected independently in each image. These points are the locations of small, distinct features which are likely to be detectable in both images. An initial network of possible matches between the two sets of candidates is constructed. Each possible match specifies a possible disparity of a candidate point in a selected reference image. An initial estimate of the probability of each possible disparity is made, based on the similarity of subimages surrounding the points. These estimates are iteratively improved by a relaxation labeling technique making use of the local continuity property of disparity that is a consequence of the continuity of real world surfaces. The algorithm is effective for binocular parallax, motion parallax, and object motion. It quickly converges to good estimates of disparity, which reflect the spatial organization of the scene.     

实践、实验与言说——深大建筑学人马拉松论坛综述

<正>2022年11月20日下午，深圳大学建筑教育办学40周年庆祝系列活动——深大建筑学人马拉松论坛在深圳大学本原设计研究中心本原讲堂举行（图1、2）。本次活动发起人为建筑与城市规划学院院长范悦，张之杨、钟中、张健蘅、陈泽涛4位校友担任活动召集人，29位校友分享了他们的个人经历，还有近50位师生代表全程参与了6小时的学术沙龙。