Microfluidic arrays for bioimprint of cancer cells

We report the development and characterization of a microfluidics-based bioimprint process using high-density microchannel arrays for cell-culture and polymer delivery. The tubeless PDMS arrays consist of multiple independent microchannels and allow for parallelized bioimprint via automated dispensing and passive pumping. Using the microchannels, a 400 nm thin test pattern was replicated into a methacrylate biopolymer to demonstrate process applicability. Bioimprints of cobalt chloride stimulated Ishikawa endometrial cancer cells exhibiting exocytosis-like pore structures were compared with controls using AFM to exemplify a process application. The devices can be used for high-throughput cell assays, cell developmental studies and the formation of phenotype-specific biomimetic scaffolds.     

Low-voltage tunable TE/TM converter on ion-sliced lithium niobate thin film

Lift-off of a prefabricated thin-film lithium niobate device using ion slicing has been demonstrated. The device is a low-voltage electro-optically tunable TE/TM mode converter, which is fabricated on a sliced 10 /spl mu/m-thick film. A new electrode configuration allows this thin-film device low-voltage tuning of the mode conversion wavelength at 0.26 nm/V. The high tuning per volt is attributed to an improved overlap integral in the thin-film form of the device.     

铝合金的大功率扩散型CO_2激光粉末焊接技术Ⅱ——铝合金焊接接头的组织与性能

本试验研究就采用扩散型CO2 激光粉末焊接技术的铝合金焊接接头进行组织及性能的分析。拉伸实验的结果表明 :对于无间隙的对接焊接头 ,采用不填粉的激光焊接工艺时的抗拉强度明显低于采用填充粉末焊接工艺 ,而且断裂也是发生在焊缝部位。但是拉伸实验的过程中可以看到明显的屈服发生在母材 ,而不是焊缝。采用填粉的激光焊接工艺时则是在母材产生屈服和最终的断裂 ;对于有间隙的对接焊接头 ,采用填粉工艺时 ,其抗拉强度不低于母材的最大间隙达 0 5mm。另外 ,采用填粉工艺的对接焊接头 ,其冷弯角可达 180°、硬度和母材相当 ;其焊缝的金相组织 ,基底为Al+Si共晶与α-Al的均匀混合物 ,其上分布有结晶时先析出的纯Si;当焊接速度偏低时 ,会发生紧邻熔合线的焊缝部位的断裂。启裂区为准解理形貌 ,扩展区面积较大并且是以准解理为主的混合断口形貌 ,终断区为韧性断口形貌     

Magnetic and Temperature‐Sensitive Release Gels from Supramolecular Polymers

Supramolecular gels consisting of trivalent polyisobutylene and bivalent poly(ethylene oxide) are generated. Strong hydrogen bonding interactions, affixed to the end‐group moieties of the respective polymers (binding constant K_assn = 10⁵ M ^–1), serve as molecular glue, leading to the formation of weak gels. Two different gels were prepared: one, with a short telechelic poly(ethylene glycol) (PEG) segment (gel A), and one with a longer PEG segment (number‐average molecular weight M_n = 2000 g mol^–1) (gel B). Both gels show a significant increase in viscosity upon mixing of the two polymeric components, with a lag time of several minutes, indicative of nucleation mechanisms as the formation principle. However, only gel A displays classical gel‐like behavior, with a loss modulus G′ larger than the storage modulus G″ after formation. Both gels display microphase‐separated behavior with a spacing between 4–5 nm as probed via small‐angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. The incorporation of magnetic nanoparticles (Fe₂O₃; radius r = 3.5 nm) is successfully achieved, generating new magnetic gels with strongly thermoresponsive properties, displaying a strong temperature‐dependent release profile of included dye molecules. Magnetic measurements indicate a superparamagnetic behavior of the incorporated nanoparticles, prospecting the application as magneto‐sensitive delivery gels for pharmaceutical purposes.     

IP QoS across multiple management domains: practical experiences from pan-European experiments

GEANT is the pan-European 10 Gbs network interconnecting European national research and educational networks (NRENs). A Premium IP service based on the DiffServ EF PHB has been specified and implemented for this environment to provide quality of service to selected user groups on a Europe-wide scale. Basic features of Premium IP are described, and results from early experiments in the production networks of GEANT and the NRENs are presented. Next steps are proposed for achieving a fast and wide availability of Premium IP in the European research networks.     

3D Printed Anatomical Nerve Regeneration Pathways

A 3D printing methodology for the design, optimization, and fabrication of a custom nerve repair technology for the regeneration of complex peripheral nerve injuries containing bifurcating sensory and motor nerve pathways is introduced. The custom scaffolds are deterministically fabricated via a microextrusion printing principle using 3D models, which are reverse engineered from patient anatomies by 3D scanning. The bifurcating pathways are augmented with 3D printed biomimetic physical cues (microgrooves) and path‐specific biochemical cues (spatially controlled multicomponent gradients). In vitro studies reveal that 3D printed physical and biochemical cues provide axonal guidance and chemotractant/chemokinetic functionality. In vivo studies examining the regeneration of bifurcated injuries across a 10 mm complex nerve gap in rats showed that the 3D printed scaffolds achieved successful regeneration of complex nerve injuries, resulting in enhanced functional return of the regenerated nerve. This approach suggests the potential of 3D printing toward advancing tissue regeneration in terms of: (1) the customization of scaffold geometries to match inherent tissue anatomies; (2) the integration of biomanufacturing approaches with computational modeling for design, analysis, and optimization; and (3) the enhancement of device properties with spatially controlled physical and biochemical functionalities, all enabled by the same 3D printing process.     

Probabilistic crisscross error correction

The crisscross error model in data arrays is considered, where the corrupted symbols are confined to a prescribed number of rows or columns (or both). Under the additional assumption that the corrupted entries are uniformly distributed over the channel alphabet, and by allowing a small decoding error probability, a coding scheme is presented where the redundancy can get close to one half the redundancy required in minimum-distance decoding of crisscross errors     

Comparison of the effect of carbon monoxide and of hypoxic hypoxia. I. In vivo metabolism, distribution and action of hexobarbital

1. The biosynthesis of cholesterol was studied, by using various precursors, in rats subjected to several dietary regimes. 2. The use of 3H2O as a substrate to demonstrate differences in cholesterogenesis under various conditions was validated by using rats fed on cholesterol or cholestyramine. Cholesterol feeding resulted in decreased cholesterogenesis, whereas cholestyramine caused an increase. 3. With acetate as precursor, the biosynthesis of both digitonin-precipitable sterol and fatty acids was increased in vitro in response to a meal. 4. In rats fed ad libitum, hepatic cholesterogenesis was increased at midnight relative to mid-morning as measured by using acetate precursor in vitro. However, no such difference was found by using 3H2O in vivo. 5. The lipogenic response was measured in meal-fed rats by using 3H2O or octanoate in vivo. In contrast with findings with acetate in vitro, no postprandial stimulation of cholesterogenesis was seen with either 3H2O or octanoate as precursor, whereas fatty acid biosynthesis from either substrate was increased. 6. These findings are discussed with respect to current theories about the circadian rhythm of cholesterogenesis. Such theories are based on experiments using isolated enzyme measurements or non-physiological precursors such as acetate. 7. It is considered that results obtained with 3H2O give an accurate representation of cholesterogenesis under various conditions, and it is therefore suggested that hepatic cholesterogenesis in rats is not subjected to the same degree of diurnal rhythm as has previously been believed.