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排序方式: 共有721条查询结果,搜索用时 375 毫秒
191.
Lukas Mai Felix Mitschker Claudia Bock Alessia Niesen Engin Ciftyurek Detlef Rogalla Johannes Mickler Matthias Erig Zheshen Li Peter Awakowicz Klaus Schierbaum Anjana Devi 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(22)
The identification of bis‐3‐(N,N‐dimethylamino)propyl zinc ([Zn(DMP)2], BDMPZ) as a safe and potential alternative to the highly pyrophoric diethyl zinc (DEZ) as atomic layer deposition (ALD) precursor for ZnO thin films is reported. Owing to the intramolecular stabilization, BDMPZ is a thermally stable, volatile, nonpyrophoric solid compound, however, it possesses a high reactivity due to the presence of Zn‐C and Zn‐N bonds in this complex. Employing this precursor, a new oxygen plasma enhanced (PE)ALD process in the deposition temperature range of 60 and 160 °C is developed. The resulting ZnO thin films are uniform, smooth, stoichiometric, and highly transparent. The deposition on polyethylene terephthalate (PET) at 60 °C results in dense and compact ZnO layers for a thickness as low as 7.5 nm with encouraging oxygen transmission rates (OTR) compared to the bare PET substrates. As a representative application of the ZnO layers, the gas sensing properties are investigated. A high response toward NO2 is observed without cross‐sensitivities against NH3 and CO. Thus, the new PEALD process employing BDMPZ has the potential to be a safe substitute to the commonly used DEZ processes. 相似文献
192.
Chenglin Zhang Yang Xu Kaiming He Yulian Dong Huaping Zhao Lukas Medenbach Yuhan Wu Andrea Balducci Thomas Hannappel Yong Lei 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(38)
Potassium‐ion batteries (PIBs) configurated by organic electrodes have been identified as a promising alternative to lithium‐ion batteries. Here, a porous organic Polyimide@Ketjenblack is demonstrated in PIBs as a cathode, which exhibits excellent performance with a large reversible capacity (143 mAh g?1 at 100 mA g?1), high rate capability (125 and 105 mAh g?1 at 1000 and 5000 mA g?1), and long cycling stability (76% capacity retention at 2000 mA g?1 over 1000 cycles). The domination of fast capacitive‐like reaction kinetics is verified, which benefits from the porous structure synthesized using in situ polymerization. Moreover, a renewable and low‐cost full cell is demonstrated with superior rate behavior (106 mAh g?1 at 3200 mA g?1). This work proposes a strategy to design polymer electrodes for high‐performance organic PIBs. 相似文献
193.
Takeshi Aoki Lukas Strizik Jan Hrabovsky Tomas Wagner 《Journal of Materials Science: Materials in Electronics》2017,28(10):7077-7082
The paper addresses the quadrature frequency resolved spectroscopy (QFRS) on the red (4 F 9/2 → 4 I 15/2) upconverted photoluminescence (UCPL) as well as the green (4 S 3/2 → 4 I 15/2) UCPL of Er3+ in GeGaS chalcogenide glasses at the pump wavelength 975 nm. On the basis of the perturbed rate equations for the generally accepted 5-level model of the green and red UCPLs of Er3+, we have derived the formulas for the QFRS on the green and red UCPLs of the two differently Er-doped samples. Adopting the respective formulas as model functions for the nonlinear regressions on the QFRS data of both the UCPLs, we have determined the relevant parameters such as relaxation rates at the four excited levels, the excited absorption cross section and energy transfer parameters. Thereby the differences of UCPL dynamics between the green and red UCPLs as well as between the two differently Er-doped Ge25Ga10S65 samples are interpreted in terms of the determined parameters. 相似文献
194.
Franz Andert Florian-M. Adolf Lukas Goormann Jörg S. Dittrich 《Journal of Intelligent and Robotic Systems》2010,57(1-4):259-280
The challenge for unmanned aerial vehicles to sense and avoid obstacles becomes even harder if narrow passages have to be crossed. An approach to solve a mission scenario that tackles the problem of such narrow passages is presented here. The task is to fly an unmanned helicopter autonomously through a course with gates that are only slightly larger than the vehicle itself. A camera is installed on the vehicle to detect the gates. Using vehicle localization data from a navigation solution, camera alignment and global gate positions are estimated simultaneously. The presented algorithm calculates the desired target waypoints to fly through the gates. Furthermore, the paper presents a mission execution plan that instructs the vehicle to search for a gate, to fly through it after successful detection, and to search for a proceeding one. All algorithms are designed to run onboard the vehicle so that no interaction with the ground control station is necessary, making the vehicle completely autonomous. To develop and optimize algorithms, and to prove the correctness and accuracy of vision-based gate detection under real operational conditions, gate positions are searched in images taken from manual helicopter flights. Afterwards, the integration of visual sensing and mission control is proven. The paper presents results from full autonomous flight where the helicopter searches and flies through a gate without operator actions. 相似文献
195.
Hess MW Pfaller K Hampölz B Longato S Teis D Flörl A Gutleben K Huber LA 《Microscopy research and technique》2006,69(2):93-98
We describe here a standardized method for histological processing of the Drosophila compound eye. Primary fixation with 2.5% glutaraldehyde, obligatorily supplemented with 0.1% household detergent regularly yielded the best structural preservation, as compared with that of other, more complicated fixation protocols tested. Notably, it proved indispensable not only to cut off the fly's head to facilitate the penetration of the reagents but also to open the chitinous head capsule. For this, we locally pierced the cuticle between the eyes, leaving the head structurally almost intact, a prerequisite for precisely aligning the head for microtomy. We developed a two-step re-embedding procedure allowing for exact and reproducible orientation of the fly heads. Thus, highly comparable series of cross sections through a representative number of ommatidia were obtained. The feasibility of our embedding and sectioning approach is finally demonstrated by three-dimensional reconstructions of the middle segments of the R1, R7, and R8 photoreceptor cells. We present reconstructions from structurally modified ommatidia, as seen after RNAi-mediated depletion of the endosomal adaptor protein p14, and from normal ommatidia corresponding to the wildtype. 相似文献
196.
With the exponential growth of moving objects data to the Gigabyte range, it has become critical to develop effective techniques
for indexing, updating, and querying these massive data sets. To meet the high update rate as well as low query response time
requirements of moving object applications, this paper takes a novel approach in moving object indexing. In our approach,
we do not require a sophisticated index structure that needs to be adjusted for each incoming update. Rather, we construct conceptually
simple short-lived index images that we only keep for a very short period of time (sub-seconds) in main memory. As a consequence, the resulting technique
MOVIES supports at the same time high query rates and high update rates, trading this property for query result staleness. Moreover, MOVIES is the first main memory method supporting time-parameterized predictive queries. To support this feature, we present two
algorithms: non-predictive MOVIES and predictive MOVIES. We obtain the surprising result that a predictive indexing approach—considered state-of-the-art in an external-memory scenario—does
not scale well in a main memory environment. In fact, our results show that MOVIES outperforms state-of-the-art moving object indexes such as a main-memory adapted B
x
-tree by orders of magnitude w.r.t. update rates and query rates. In our experimental evaluation, we index the complete road
network of Germany consisting of 40,000,000 road segments and 38,000,000 nodes. We scale our workload up to 100,000,000 moving
objects, 58,000,000 updates per second and 10,000 queries per second, a scenario at a scale unmatched by any previous work. 相似文献
197.
198.
Reza Haschemi Lukas Maria Gockel Gerd Bendas Martin Schlesinger 《International journal of molecular sciences》2021,22(7)
Pancreatic cancer patients have an elevated risk of suffering from venous thrombosis. Among several risk factors that contribute to hypercoagulability of this malignancy, platelets possess a key role in the initiation of clot formation. Although single mechanisms of platelet activation are well-known in principle, combinations thereof and their potential synergy to mediate platelet activation is, in the case of pancreatic cancer, far from being clear. Applying an inhibitor screening approach using light transmission aggregometry, dense granule release, and thrombin formation assays, we provide evidence that a combination of tissue factor-induced thrombin formation by cancer cells and their platelet P-selectin binding is responsible for AsPC-1 and Capan-2 pancreatic cancer cell-mediated platelet activation. While the blockade of one of these pathways leads to a pronounced inhibition of platelet aggregation and dense granule release, the simultaneous blockade of both pathways is inevitable to prevent platelet aggregation completely and minimize ATP release. In contrast, MIA PaCa-2 pancreatic cancer cells express reduced levels of tissue factor and P-selectin ligands and thus turn out to be poor platelet activators. Consequently, a simultaneous blockade of thrombin and P-selectin binding seems to be a powerful approach, as mediated by heparin to crucially reduce the hypercoagulable state of pancreatic cancer patients. 相似文献
199.
200.
Lukas Seebauer Yanni Schneider Alice Drobny Sonja Pltz Tomas Koudelka Andreas Tholey Iryna Prots Beate Winner Friederike Zunke Jürgen Winkler Wei Xiang 《International journal of molecular sciences》2022,23(3)
Parkinson’s disease (PD) is neuropathologically characterized by the loss of dopaminergic neurons and the deposition of aggregated alpha synuclein (aSyn). Mounting evidence suggests that neuritic degeneration precedes neuronal loss in PD. A possible underlying mechanism could be the interference of aSyn with microtubule organization in the neuritic development, as implied by several studies using cell-free model systems. In this study, we investigate the impact of aSyn on microtubule organization in aSyn overexpressing H4 neuroglioma cells and midbrain dopaminergic neuronal cells (mDANs) generated from PD patient-derived human induced pluripotent stem cells (hiPSCs) carrying an aSyn gene duplication (SNCADupl). An unbiased mass spectrometric analysis reveals a preferential binding of aggregated aSyn conformers to a number of microtubule elements. We confirm the interaction of aSyn with beta tubulin III in H4 and hiPSC-derived mDAN cell model systems, and demonstrate a remarkable redistribution of tubulin isoforms from the soluble to insoluble fraction, accompanied by a significantly increased insoluble aSyn level. Concordantly, SNCADupl mDANs show impaired neuritic phenotypes characterized by perturbations in neurite initiation and outgrowth. In summary, our findings suggest a mechanistic pathway, through which aSyn aggregation interferes with microtubule organization and induces neurite impairments. 相似文献