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1.
Despite the potential benefits of virtual teams, current literature suggests that virtual teamwork is rife with complex challenges. We frame some of these challenges as paradoxes inherent in the concept of virtual teamwork. Based on interviews with 42 leaders and members of virtual teams, we identify five paradoxes: (1) virtual teams require physical presence; (2) flexibility of virtual teamwork is aided by structure; (3) interdependent work in virtual teams is accomplished by members' independent contributions; (4) task-oriented virtual teamwork succeeds through social interactions; and (5) mistrust is instrumental to establishing trust among virtual team members. In addition, we identify strategies that respondents used to cope with, or 'survive' the paradoxes of virtual teamwork. 相似文献
2.
Yasmin Srivastava Christopher Rhodes Manuel Marquez Todd Thorsen 《Microfluidics and nanofluidics》2008,5(4):455-458
Hollow poly (vinylpyrrolidone) (PVP) + TiO2 and polypyrrole (core)/PVP (sheath) nanofibers were successfully electrospun using hydrodynamic fluid focusing. Utilizing
a two-dimensional fluid focusing technique previously applied to aqueous solutions, intersecting microchannels cast in (poly)dimethylsiloxane
were utilized to dynamically center core fluids in immiscible sheath fluids prior to electrospinning at the channel outlet.
Advantages of using microfluidic channel networks for the electrospinning of composite nanofibers include spatiotemporal control
over input reagents, ease of fabrication and the ability to focus the core stream into sheath layer without the need of complex
co-annular nozzles. 相似文献
3.
Min-Cheol Kim Raymond H. W. Lam Todd Thorsen H. Harry Asada 《Microfluidics and nanofluidics》2013,15(3):285-296
For successful cell culture in microfluidic devices, precise control of the microenvironment, including gas transfer between the cells and the surrounding medium, is exceptionally important. The work is motivated by a polydimethylsiloxane (PDMS) microfluidic oxygenator chip for mammalian cell culture suggesting that the speed of the oxygen transfer may vary depending on the thickness of a PDMS membrane or the height of a fluid channel. In this paper, a model is presented to describe the oxygen transfer dynamics in the PDMS microfluidic oxygenator chip for mammalian cell culture. Theoretical studies were carried out to evaluate the oxygen profile within the multilayer device, consisting of a gas reservoir, a PDMS membrane, a fluid channel containing growth media, and a cell culture layer. The corresponding semi-analytical solution was derived to evaluate dissolved oxygen concentration within the heterogeneous materials, and was found to be in good agreement with the numerical solution. In addition, a separate analytical solution was obtained to investigate the oxygen pressure drop (OPD) along the cell layer due to oxygen uptake of cells, with experimental validation of the OPD model carried out using human umbilical vein endothelial cells cultured in a PDMS microfluidic oxygenator. Within the theoretical framework, the effects of several microfluidic oxygenator design parameters were studied, including cell type and critical device dimensions. 相似文献
4.
The new concept, anion substitution, is explored for possible improvement of hydrogen storage properties in the system LiBH4-LiI. The structural chemistry and the substitution mechanism are analyzed using Rietveld refinement of in situ synchrotron radiation powder X-ray diffraction (SR-PXD) data, attenuated total reflectance infrared spectroscopy (ATR-IR), differential scanning calorimetry (DSC) and Sieverts measurements. Anion substitution is observed as formation of two solid solutions of Li(BH4)1−xIx, which merge into one upon heating. The solid solutions have hexagonal structures (space group P63mc) similar to the structures of h-LiBH4 and β-LiI. The solid solutions have iodide contents in the range ∼0-62 mol% and are stable from below room temperature to the melting point at 330 °C. Thus the stability of the solid solutions is higher as compared to that of the orthorhombic and hexagonal polymorphs of LiBH4 and α- and β-LiI. Furthermore, the rehydrogenation properties of the iodide substituted solid solution Li(BH4)1−xIx, measured by the Sieverts method, are improved as compared to those of LiBH4. After four cycles of hydrogen release and uptake the Li(BH4)1−xIx solid solution maintains 68% of the calculated hydrogen storage capacity in contrast to LiBH4, which maintains only 25% of the storage capacity after two cycles under identical conditions. 相似文献
5.
Line Riis Christensen Ole Hassager Anne Ladegaard Skov 《American Institute of Chemical Engineers》2020,66(8):e16275
Multiple breakdown phenomena may take place when operating dielectric elastomers. Thermal breakdown, which occurs due to Joule heating, becomes of special importance when using multilayered stacks of dielectric elastomers, due to the large volume-to-surface-area-ratio. In this article, a 2D axisymmetric finite-element model of a multilayered stack of dielectric elastomers is set up in COMSOL Multiphysics®. Both the electro-thermal and electro-mechanical couplings are considered, allowing for determination of the onset of thermal breakdown. Simulation results show that an entrapped particle in the dielectric elastomer drastically reduces the possible number of layers in the stack. Furthermore, the possible number of layers is greatly affected by the ambient temperature and the applied voltage. The performance of three hyperelastic material models for modeling the elastomer deformation are compared, and it is established that the Gent model yields the most restrictive prediction of breakdown point, while the Ogden model yields the least restrictive estimation. 相似文献
6.
Lars Peter Andersen Line Nørdam Thomas Joensson Pete Kines Kent J. Nielsen 《Construction Management & Economics》2018,36(1):22-31
The construction industry has one of the highest frequencies of work-related accidents. We examined whether construction workers predominantly identify themselves in terms of their workgroup or in terms of the construction site. In addition, we examined the associations between social identity and safety climate, and how these constructs are associated with work-related accidents. The analyses were based on questionnaire responses from 478 construction workers from two large construction sites, and the methods involved structural equation modeling. Results showed that the workers identified themselves primarily with their workgroup, and to a lesser degree with the construction site. Social identity and safety climate were related both at the workgroup and construction site levels, meaning that social identity may be an antecedent for safety climate. The association between social identity and safety climate was stronger at the workgroup level than at the construction site level. Finally, safety climate at both levels was inversely associated with self-reported accidents, with the strongest association at the workgroup level. A focus on improving safety climate, particularly by integrating initiatives at both the workgroup and management level, may have the potential to improve safety performance and thus decrease the risk of accidents and injuries on construction sites. 相似文献
7.
Alexander Hgsted Ahlmann Shu Fang Sussi Bagge Mortensen Line Weis Andersen Pernille Gejl Pedersen Johanne Juel Callesen Sara Thornby Bak Kate Lykke Lambertsen Ditte Caroline Andersen 《International journal of molecular sciences》2021,22(15)
Small diameter (<6 mm) vessel grafts still pose a challenge for scientists worldwide. Decellularised umbilical artery (dUA) remains promising as small diameter tissue engineered vascular graft (TEVG), yet their immunogenicity remains unknown. Herein, we evaluated the host immune responses, with a focus on the innate part, towards human dUA implantation in mice, and confirmed our findings in an ex vivo allogeneic human setup. Overall, we did not observe any differences in the number of circulating white blood cells nor the number of monocytes among three groups of mice (1) dUA patch; (2) Sham; and (3) Mock throughout the study (day −7 to 28). Likewise, we found no difference in systemic inflammatory and anti-inflammatory cytokine levels between groups. However, a massive local remodelling response with M2 macrophages were observed in the dUA at day 28, whereas M1 macrophages were less frequent. Moreover, human monocytes from allogeneic individuals were differentiated into macrophages and exposed to lyophilised dUA to maximize an eventual M1 response. Yet, dUA did not elicit any immediate M1 response as determined by the absence of CCR7 and CXCL10. Together this suggests that human dUA elicits a minimal pro-inflammatory response further supporting its use as a TEVG in an allogeneic setup. 相似文献
8.
9.
馒头连续化生产线工艺及设备的研究 总被引:1,自引:0,他引:1
目前馒头生产一直是手工作坊和间歇式生产,产量低、能耗高、劳动强度大.本文论述了馒头连续化生产线的工艺条件和设备装置,并实现了馒头连续化生产. 相似文献
10.
易志华 《武汉理工大学学报》2002,24(8):93-95
名牌战略是企业参与现代市场竞争的一项重要战略,基于中国国内名牌与世界名牌的差距,对创建中国名牌应走出的误区以及应采取的相应措施进行了有益的探讨。 相似文献