Characterization of anterior cruciate ligament cells and bone marrow stromal cells on various biodegradable polymeric films

In this study, the adhesion, proliferation and morphology of rabbit anterior cruciate ligament (ACL) cells and bone marrow stromal cells (bMSCs) on synthetic biodegradable polymeric films were investigated. Tissue culture polystyrene (TCP) was used as control. Seven biodegradable polymers were used; they are as follows: poly(-caprolactone) (PCL), poly( -lactide) ( -PLA), poly( -lactide) ( -PLA), PLA/PCL (50:50), PLA/PCL (75:25), high molecular weight (HMW) poly( -lactide–co-glycolide (PLGA50:50) and HMW PLGA75:25. Polymeric film substrates were manufactured using solvent spin-casting technique. After 8 h of cell culture, a high percentage of ACL cells was found attached to PLGA50:50 (38.6±8.4%) and TCP (39.3±6.1%) as compared to the other six polymeric films (p≤0.001). As for bMSCs, 76.4±10%, 76.3±16% and 76.1±19% of seeded bMSCs were adhered to TCP, PLGA50:50 and PLGA75:25, respectively. These were significantly more than those of the other five polymeric films (p<0.001). At Day 5, bMSCs were found to proliferate faster on TCP (by 7±0.8-fold of initial cell seeding number), -PLA (by 5.6±1.6-fold), PLGA50:50 (by 9.3±1.3-fold) and PLGA75:25 (by 5.8±1.3-fold) than on PCL, PLLA and PCL/PLA (50:50, 25:75) (p<0.001). ACL cells had a greater fold expansion on TCP (by 3.5±0.2-fold), PLGA50:50 (by 3.1±0.4-fold) and PLGA75:25 (by 3.9±0.4-fold) than on the other five polymer substrates (p<0.001). From these results, HMW PLGA (50:50, 75:25) was shown more likely to allow bMSCs and ACL cells to attach and proliferate, and bMSCs attached and proliferated faster than ACL cells.     

Short-term effects of a teenage driver cell phone restriction

On December 1, 2006, North Carolina began prohibiting use of any mobile communication device by drivers younger than 18. The current study examined the effects of the law on teenage drivers’ cell phone use. Teenage drivers were observed at high schools in North Carolina 1-2 months before and approximately 5 months after the law took effect. The proportion of teenagers using cell phones did not change significantly (11.0% before the law took effect, 11.8% after). Cell phone use among teenage drivers at high schools in South Carolina, an adjacent state without a teenage driver phone ban, was stable at about 13%. Interviews were conducted with parents and teenagers in North Carolina both before and after the law took effect. In post-law interviews, teenagers were more likely than parents to say they knew about the cell phone restriction (64% vs. 39%), but support for the ban was greater among parents (95% vs. 74%). Only 22% of teenagers and 13% of parents believed the law was being enforced fairly often or a lot. Although the proportion of teenagers who reported using phones while driving declined somewhat following the law, about half admitted they used their phones, if they had driven, on the day prior to the interview. Overall, the findings suggest that North Carolina's cell phone restriction had little to no effect on teenage drivers’ use of cell phones shortly after the law took effect.     

Effects of calcium-phosphate topography on osteoblast mechanobiology determined using a cytodetacher

The Human fetal osteoblast (hFOB) cell morphology, adhesion force, and proliferation on a calcium-phosphate (Ca-P) micropattern surface were investigated and the mechanobiology was investigated by a cytodetachment test. Ca-P-coated groove patterns with 3.0-μm-deep grooves (C3), 4.5-μm-deep grooves (C4), and 5.5-μm-deep grooves (C5) were produced on silicon wafers using photolithography and wet etching techniques. The grooved substrates were coated with a 200-nm-thick layer of titanium (bond coat) and a 200-nm-thick layer of calcium phosphate (top coat) using a sputtering system. Smooth Ca-P-coated Si wafers were used as control surfaces. Analysis of the scanning electron microscopy observations shows that cells on the Ca-P micropattern showed spreading and elongation. The MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay indicated that C3 and C4 specimens had a significantly higher number of cells than did the control group after 5- and 15-day cultures. The cyto-compatibility of specimens was quantitatively evaluated using a cytodetacher, which directly measures the detachment shear force of an individual cell to the substrate. After 30-min culture, the cell adhesion forces were 38.4 nN for the smooth specimen, 140.8 nN for C3, 124.2 nN for C4, and 67.1 nN for C5. The results indicate that the cell adhesion force is influenced by cell shape and the Ca-P grooved patterns affect the cell shape and cytoskeletal structure, thus influence cell proliferation and cell adhesion force. The cytodetachment test with nanonewton resolution is a sensitive method for studying cell-biomaterial interaction.     

Effects of Three-Dimensional Platform Stiffness and Layer Dimensions on Separation of Carcinoma Cells

Cancer cell separation is highly desirable for cancer diagnosis and therapy. Besides biochemical methods, engineered platforms are effective alternatives for sorting carcinoma cells from normal cells based on their unique properties in responding to the physical changes of the surrounding microenvironment. In this work, three-dimensional (3D) biomimetic scaffold platforms were developed to separate nasopharyngeal carcinoma 43 (NPC43) cells from immortalized nasopharyngeal epithelial 460 (NP460) cells based on precisely controlled design parameters including stiffness, number of layers, and structural layout. The migration characteristics of NPC43 and NP460 cells on the scaffold platforms revealed that NPC43 cells could squeeze into 10 μm wide, 15 μm deep trenches while NP460 cells could not. The different migration behavior was mainly due to cells having different interactions with the surrounding microenvironment. NPC43 cells had filopodia-like protrusions, while NP460 cells exhibited a sheet-like morphology. Using these 3D biomimetic platforms, 89% separation efficiency of NPC43 cells from NP460 cells was achieved on stiffer two-layer scaffold platforms with a 40/10 μm ridge/trench (R/T) grating on the top layer and a 20/10 μm R/T grid on the bottom layer. Moreover, the separation efficiency was further increased to 93% by adding an active conditioned medium (ACM) that caused the cells to have higher motility and deformability. These results demonstrate the capability to apply biomimetic engineered platforms with appropriate designs to separate cancer cells from normal cells for potential cancer diagnosis and treatment.     

Polymer nanocomposite foams

Polymer nanocomposite foams have received increasingly attention in both scientific and industrial communities. The combination of functional nanoparticles and supercritical fluid foaming technology has a high potential to generate a new class of materials that are lightweight, high strength and multifunctional. A small amount of well-dispersed nanoparticles in the polymer domain may serve as the nucleation sites to facilitate the bubble nucleation process. Moreover, the nano-scaled particles are suitable for micro-scaled reinforcement, thus achieving the macroscopic mechanical enhancement. In this paper, we will first briefly review the synthesis and processing techniques of nanocomposites based on polymers that are important in the foam industry. Both thermoplastic and thermoset nanocomposite foams will be addressed. This is followed by an introduction of various foaming techniques. The effect of nanoparticles on the foam morphology and properties is then discussed. We conclude with the current and future trends of nanocomposite foams in both industrial and biomedical applications.     

在APON中实现全业务接入的MAC协议设计

结合以ATM为基础的无源光网络 (APON)的G .983建议 ,提出了一个能同时实现话音业务、一般ATM业务和IP业务接入的媒质接入控制 (MAC)协议。通过建模仿真 ,分析了该协议的时延和时延变化性能。     

CAC－CIMS中FDNC生产线控制的研究和开发

以ＣＡＣ－ＣＩＭＳ中的单元控制器、制造工作站控制器、ＤＮＣ接口控制器的研究与开发为背景，着重对柔性数控（ＦＤＮＣ）生产线的递阶控制结构、系统功能、系统设计和实现的关键技术及运行等进行了论述。     

基于ATM的无源光网络的媒质接入控制(MAC)协议及其性能分析

结合以ＡＴＭ为基础的无源光网络的Ｇ．９８３建议,提出了一个基于预留的 接入控制协议,通过建模仿真,分析了此协议在多种业务流组合下的时延和时延变化性能,并提出了一种硬件实现方案。     

Effect of North Carolina's restriction on teenage driver cell phone use two years after implementation

A majority of states now restrict teenagers from using a mobile communication device while driving. The effect of these restrictions is largely unknown. In a previous study, we found North Carolina's teenage driver cell phone restriction had little influence on young driver behavior four months after the law took effect (Foss et al., 2009). The goal of the present study was to examine the longer-term effect of North Carolina's cell phone restriction. It was expected that compliance with the restriction would increase, as awareness of the restriction grew over time. Teenagers were observed at high schools in North Carolina approximately two years after the law was implemented. Observations were also conducted in South Carolina, which did not have a cell phone restriction. In both states, there was a broad decrease in cell phone use. A logistic regression analysis showed the decrease in cell phone use did not significantly differ between the two states. Although hand-held cell phone use decreased, there was an increase in the likelihood that drivers in North Carolina were observed physically manipulating a phone. Finally, a mail survey of teenagers in North Carolina showed awareness for the cell phone restriction now stands at 78% among licensed teens. Overall, the findings suggest North Carolina's cell phone restriction has had no long-term effect on the behavior of teenage drivers. Moreover, it appears many teenage drivers may be shifting from talking on a phone to texting.     

Psychological predictors of college students’ cell phone use while driving

Despite the known risk, many people talk on a phone while driving. This study explored psychological predictors of cell phone use while driving. College students (final N = 69) completed a survey and predicted their driving performance both with and without a simultaneous phone conversation. Their actual performance on a driving simulator was then assessed. Cell phone use reduced performance on the simulation task. Further, perceiving oneself as good at compensating for driving distractions, overestimating one's performance on the driving simulator, and high illusory control predicted more frequent cell phone use while driving in everyday life. Finally, those who talked more frequently on a phone while driving had poorer real-world driving records. These findings suggest illusory control and positive illusions partly explain driver's decisions of whether to use cell phones while driving.     

牙鲆淋巴囊肿病毒在牙鲆鳃细胞系FG-9307中的增殖

向已建立的牙鲆（Paralichthys olivaceus）鳃细胞系^[1](FG-9307)中接种淋巴囊肿病（Lymphocystis disease virus,LCDV）、探讨其是否可支持LCDV的增殖。光学显微镜观察发现：接种3天后，呈纤维状的鳃细胞隆起、立体感加强；之后细胞逐渐变圆，一周左右绝大部分鳃细胞变圆、呈现了细胞病变（cytopathic effect,CPE）现象。将CPE细胞制作超薄切片，电镜观察发现细胞内有大量具囊膜、直径133－186nm的LCDV。CPE细胞的核变形、线粒体增加且空洞化，出现了与淋巴囊肿细胞相同的特征。本实验证明：FG－9307是可持续LCDV增殖的鱼类细胞系。     

Synthesis, Characterization, and Cytotoxicity Analysis of a Biodegradable Polyurethane

A polyester urethane was synthesized for use in a biodegradable scaffold. The polyurethane was synthesized in a two-step process: first, ester diol was synthesized from lactic acid and polyethylene glycol 400 (PEG 400), then it was polymerized with toluene diisocyanate using dibutyl tin dilaurate (DBTDL) as a catalyst to form a polyester urethane. Polyester urethane has tensile strength of 51-59 MPa and elongation at fracture of 369-439%. FTIR and XRD were used to confirm the formation and structure of the polymer. Hydrolytic degradation was studied in different alkali solutions and in saline water. In order to assess the cellular response of this material, cytotoxicity analysis was carried out against the cell line.     

Effect of process conditions on dynamics and performance of PEMFC: Comparison with experiments

Three-dimensional numerical computations have been carried out to investigate the dynamics inside proton-exchange membrane fuel cell (PEMFC) and its performance using Star-CD solver, the computational fluid dynamics software. Theoretical results in polarization curves quantitatively corroborate the experimental findings previously reported in Jung et al. [2]. Also, effects of various process conditions such as relative humidity, stoichiometric ratio at anode and cathode channels, and cell configuration on the performance of fuel cell have been further scrutinized. It has been revealed that the moderately high stoichiometric ratio at cathode channel and single serpentine geometry improve the cell performance and also the humidity change at cathode makes the cell voltage variation high, comparing with the humidity change at anode.     

Living scaffolds for neuroregeneration

Neural tissue engineers are exploiting key mechanisms responsible for neural cell migration and axonal pathfinding during embryonic development to create living scaffolds for neuroregeneration following injury and disease. These mechanisms involve the combined use of haptotactic, chemotactic, and mechanical cues to direct cell movement and re-growth. Living scaffolds provide these cues through the use of cells engineered in a predefined architecture, generally in combination with biomaterial strategies. Although several hurdles exist in the implementation of living regenerative scaffolds, there are considerable therapeutic advantages to using living cells in conjunction with biomaterials. The leading contemporary living scaffolds for neurorepair are utilizing aligned glial cells and neuronal/axonal tracts to direct regenerating axons across damaged tissue to appropriate targets, and in some cases to directly replace the function of lost cells. Future advances in technology, including the use of exogenous stimulation and genetically engineered stem cells, will further the potential of living scaffolds and drive a new era of personalized medicine for neuroregeneration.     

Studies on toxicity of multi-walled carbon nanotubes on Arabidopsis T87 suspension cells

The possible toxicities of agglomerates of multi-walled carbon nanotubes (MWCNTs) toward plant cells were evaluated. Arabidopsis T87 suspension cells were used as the model cells and decreases in values of cell dry weights, cell viabilities, cell chlorophyll contents, and superoxide dismutase (SOD) activities were seen for the cells cultured in media containing the agglomerates of MWCNTs, indicating the agglomerates of MWCNTs are toxic to the Arabidopsis T87 suspension cells. Moreover, the toxicities increased sharply as the diameters of the agglomerates of the MWCNTs became smaller. A concept based on the hypersensitive response is suggested to explain the possible toxic mechanism induced by the MWCNTs.     

细胞融合构建新型微藻及融合子的筛选和鉴定

利用细胞化学融合法，将生长迅速的兼养微藻和富含EPA和DHA的自养微藻进行融合。根据两种亲本藻的不同生长特性和脂肪酸组成差异，筛选出一种新型的微藻。利用随机扩增多态性技术（RAPD），对融合子进行鉴定，确认融合子为一种新型的微藻。     

通用单元控制器的研究

介绍了与ＦＭＳ／ＣＩＭＳ发展相适应的通用的单元控制器的开放体系结构，给出了一个不随具体环境而改变的通用单元控制器的设计方法和实现技术。这种新型的通用单元控制器正在被用来替代从国外进口的ＦＦＳ５００－２ ＦＭＳ控制器。     

发动机试验室的通风（空调）热负荷计算

为了确定一种常见的水冷式柴油发动机试验室内的通风（空调）热负荷值,采用一种简化的等效体表面换热模型,用以计算出该发动机的对流和辐射换热负荷（简称“等效计算法”）;并对采用不同计算（或估算）方法得出的换热负荷值进行比较分析,推荐了在一定条件下发动机散热系数的经验取值范围,供此类暖通设计者参考。     

Langmuir Probe Measurements in the Gaseous Electronics Conference RF Reference Cell

The use of a Langmuir probe system in two GEC cells is reviewed. The major problems associated with probe diagnostics in a GEC cell are outlined and discussed. While the data base is still insufficient to give definitive values for many parameters, a number of standard measurements are put forward. The plasma density in argon is 9×10⁹ cm⁻³ (±20 %) at an applied rf voltage of 250 V (500 V peak to peak) and a gas pressure of 13.3 Pa (100 mTorr). The electron density scales linearly with applied voltage. The plasma to ground sheath resistance is shown to be very important with a value of 810 Ω in argon at a pressure of 13.3 Pa (100 mTorr) and discharge current of 0.1 A. The value of plasma to ground resistance scales inversely with discharge current and sublinear with pressure. Two standard features in the electron energy distribution function (EEDF) have been proposed as a test of the ability of a probe system to resolve features, first, the transition from a low temperature (<1 eV) bi-Maxwellian distribution to a Druyveysten distribution (3 eV) at 13.3 Pa (100 mTorr) in argon, and the “hole” in the EEDF at 2 eV to 4 eV in nitrogen plasmas.