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排序方式: 共有101条查询结果,搜索用时 46 毫秒
41.
A method for rapidly assembling high-density DNA arrays with near-perfect order is described. Photolithography is used to generate a wafer-scale array of microwells in a layer of photoresist on a chemically functionalized glass coverslip. The array is enclosed within a microfluidic device, and a suspension of superparamagnetic microbeads conjugated to DNA molecules is introduced into the chamber. A permanent magnet is used to direct the rapid assembly of the beads into the wells, with each well containing a single bead. These beads are immobilized on the glass surface via affinity binding, and excess beads can be recycled or washed away. Nonspecifically bound beads are removed by dissolving the photoresist. The result is a high-density array of beads with virtually no background. This method can be used to produce protein arrays for chip-based assays and DNA arrays for genotyping or genome sequencing. 相似文献
42.
Solid State Foaming of Nickel,Monel, and Copper by the Reduction and Expansion of NiO and CuO Dispersions 下载免费PDF全文
Mark A. Atwater Thomas L. Luckenbaugh B. Chad Hornbuckle Kristopher A. Darling 《Advanced Engineering Materials》2018,20(9)
Nickel and its alloys are useful in a range of applications, and nickel foams have increased in popularity for functional applications, such as electrodes. Despite their versatility and interest for burgeoning technologies, there is only one well‐developed method for producing porous nickel commercially. This work introduces a simple method for creating porosity in nickel and Monel (70% Ni, 30% Cu) that results in sub‐micron to micron‐scale pores and grains. This is accomplished by creating oxide dispersions in the metallic matrix and then reducing those oxides at elevated temperature to form pores. It is found that nickel and Monel reach maximum porosity at 800 °C with Monel reaching a higher overall porosity (33% vs. 25% for Ni), whereas Cu exhibited 40% porosity under the same conditions. Varied matrix and oxide pairings are examined microstructurally, and the effects of matrix strength, oxide chemistry, and other factors are considered to determine factors in pore development. Uniquely, this method produces pores within individual metallic particles, so this porosity can be added to other powder methods of solid state foaming to enhance the performance in functional applications. 相似文献
43.
Soumya Nag Sameer R. Paital Peeyush Nandawana Kristopher Mahdak Yee Hsien Ho Hitesh D. Vora Rajarshi Banerjee Narendra B. Dahotre 《Materials science & engineering. C, Materials for biological applications》2013,33(1):165-173
A high intensity continuous wave diode pumped ytterbium laser source was used to deposit Ca–P coatings on a Ti–6Al–4V biocompatible alloy in order to generate a physically textured surface, enhancing osseointegration. Scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) studies were coupled with X-ray and micro diffraction work to determine the structure, composition, and phases present in various zones of a sample prepared across the coating/substrate interaction zone. Three-dimensional thermal modeling was also carried out to determine the cooling rate and maximum temperature experienced by different regions of the substrate. Combining these results provide us with valuable insights regarding the thermo-physical as well as chemical interactions that take place across the coating–substrate interface. 相似文献
44.
Hennessy Michael B.; Paik Kristopher D.; Caraway Jessica D.; Schiml Patricia A.; Deak Terrence 《Canadian Metallurgical Quarterly》2011,125(3):426
When guinea pig pups are isolated for a few hours in a novel environment, they exhibit a distinctive passive behavioral response that appears to be mediated by proinflammatory activity. Recently, we observed that pups separated on two consecutive days show an enhanced (sensitized) passive response on the second day. In Experiment 1, pups receiving intracerebroventricular infusion of 50 ng of the anti-inflammatory cytokine interleukin-10 prior to a first separation failed to show a sensitized behavioral response to separation the next day. In Experiment 2, pups separated on Days 1 and 2, or just 2, showed an increase in passive responding during separation on Day 5. Pups injected with the bacterial antigen lipopolysacchride (LPS; 75 μg/kg body weight, intraperitoneal) prior to separation on Day 1 showed an increase in passive behavior several days later not shown by pups injected with saline prior to Day 1 separation. However, injection of LPS without separation on the first day did not enhance responding during an initial separation on the second day. These results suggest that immune activation is necessary, but not sufficient, to account for the sensitization of passive behavior of isolated guinea pig pups the following day, that boosting proinflammatory activity during an initial separation may promote sensitization several days later, and that the sensitized response persists for at least several days. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
45.
PR Erickson M Grandbois WA Arnold K McNeill 《Environmental science & technology》2012,46(15):8174-8180
The photochemical conversion of selected hydroxylated polybrominated diphenyl ethers (OH-PBDEs) to dioxins and other products was investigated. OH-PBDEs, which are both transformation products of polybrominated diphenyl ethers and naturally occurring compounds, undergo direct photolysis to yield a number of products that may have a higher toxicity than their parent. The compounds investigated were 6-OH-PBDE 99, 6'-OH-PBDE 100, and 6'-OH-PBDE 118. Of special interest was 6'-OH-PBDE 118, a potential transformation product of PBDE 153 that is capable of photochemically generating 2,3,7,8-tetrabromodibenzo-p-dioxin, the most toxic brominated dioxin congener. Photolysis experiments were conducted at two different pH values to assess the photochemical behavior of both the phenol and phenolate form of the compounds. The percent conversion to dioxin and other photoproducts was determined and the natural product, 6-OH-PBDE 99, was found to have the highest conversion to dioxin (7%). The reaction quantum yields ranged from 0.027 to 0.16 across all photolysis conditions. In addition, it is shown that all three compounds are capable of photochemically generating other compounds of concern, including brominated phenols and a dibenzofuran. 相似文献
46.
Hautefeuille M Jimenez-Zenteno AK Pérez-Alcázar PR Hess-Frieling KM Fernandez-Sanchez G Velazquez V Grether-Gonzalez M Lopez-Moreno E 《Applied optics》2012,51(8):1171-1177
Laser microfabrication is now offering interesting solutions to rapidly produce high-resolution photomasks or microstructures. However, most works require expensive commercial lasers and computer numerical control platforms, limiting its use by a large public. In this paper, we report the construction of a simple, custom-made, easily reproducible, automated laser system, based on a DVD optical pickup head. A user-friendly computer interface specifically designed to operate a motorized three-axis platform with micrometric precision controls focus distance and in-plane displacements. Writing performance characterization for both direct ablation and sintering of commercial black toner demonstrated flexibility in tridimensional microfabrication resolution and speed thanks to precise management of laser power and exposure time, with a minimal resolution of 3.1 μm. 相似文献
47.
Dell Gary S.; Reed Kristopher D.; Adams David R.; Meyer Antje S. 《Canadian Metallurgical Quarterly》2000,26(6):1355
Speech errors follow the phonotactics of the language being spoken. For example, in English, if [n] is mispronounced as [ ], the [ ] will always appear in a syllable coda. The authors created an analogue to this phenomenon by having participants recite lists of consonant–vowel–consonant syllables in 4 sessions on different days. In the first 2 experiments, some consonants were always onsets, some were always codas, and some could be both. In a third experiment, the set of possible onsets and codas depended on vowel identity. In all 3 studies, the production errors that occurred respected the "phonotactics" of the experiment. The results illustrate the implicit learning of the sequential constraints present in the stimuli and show that the language production system adapts to recent experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
MacCallum Robert C.; Zhang Shaobo; Preacher Kristopher J.; Rucker Derek D. 《Canadian Metallurgical Quarterly》2002,7(1):19
The authors examine the practice of dichotomization of quantitative measures, wherein relationships among variables are examined after 1 or more variables have been converted to dichotomous variables by splitting the sample at some point on the scale(s) of measurement. A common form of dichotomization is the median split, where the independent variable is split at the median to form high and low groups, which are then compared with respect to their means on the dependent variable. The consequences of dichotomization for measurement and statistical analyses are illustrated and discussed. The use of dichotomization in practice is described, and justifications that are offered for such usage are examined. The authors present the case that dichotomization is rarely defensible and often will yield misleading results. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
49.
Trevor C. Bozeman Katie A. Edwards Kristopher M. Fecteau Michael G. Verde Jr. Alex Blanchard Danielle L. Woodall Nicholas Benfaremo James R. Ford Jerome L. Mullin Caryn K. Prudente Henry J. Tracy 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(2):316-326
The syntheses, spectroscopic characteristics, and electrochemical behavior of 1,1-dimethyl-2,5-diphenyl-3,4-bis(p-methylphenyl)silole and 1,1-dimethyl-2,3,4,5-tetra(p-methylphenyl)silole are reported. The compounds are weakly luminescent in dilute fluid solution but exhibit dramatic aggregation-induced emission (AIE). Absorbance, luminescence, and voltammetric characteristics are compared to 1,1-dimethyl-2,3,4,5-tetraphenylsilole and 1,1-dimethyl-3,4-diphenyl-2,5-bis(p-methylphenyl)silole, allowing a comparison of the effects of the position of the substituents on the silole ring. In addition, HOMO and LUMO energies and band gaps, derived from electrochemical, spectroscopic, and computational data, are reported. Substitution of the weakly electron-donating p-methyl groups on the peripheral aryl groups at the 2- and 5-positions of the silole ring results in slight red shifts in absorption and emission maxima, slight enhancement of luminescence quantum yields, slightly longer luminescence lifetimes, and more anodic oxidation potentials. 相似文献
50.
Sara Romanazzo Thomas Gregory Molley Stephanie Nemec Kang Lin Rakib Sheikh John Justin Gooding Boyang Wan Qing Li Kristopher Alan Kilian Iman Roohani 《Advanced functional materials》2021,31(13):2008216
The integration of hierarchical structure, chemistry, and functional activity within tissue-engineered scaffolds is of great importance in mimicking native bone tissue. Bone is a highly mineralized tissue which forms at ambient conditions by continuous crystallization of the mineral phase within an organic matrix in the presence of bone residing cells. Despite recent advances in the biofabrication of complex engineered tissues, replication of the heterogeneity of bone microenvironments has been a major challenge in constructing biomimetic bone scaffolds. Herein, inspired by the bone biomineralization process, the first example of bone mimicking constructs by 3D writing of a novel apatite-transforming ink in a supportive microgel matrix with living cells is demonstrated. Using this technique, complex bone-mimicked constructs are made at room temperature without requiring invasive chemicals, radiation, or postprocessing steps. This study demonstrates that mineralized constructs can be deposited within a high density of stem cells, directing the cellular organization, and promoting osteogenesis in vitro. These findings offer a new strategy for fabrication of bone mimicking constructs for bone tissue regeneration with scope to generate custom bone microenvironments for disease modeling, multicellular delivery, and in vivo bone repair. 相似文献