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排序方式: 共有3623条查询结果,搜索用时 23 毫秒
101.
Stephanie Ehlers Dr. Daiane Szczerbowski Dr. Tim Harig Dr. Matthew Stell Dr. Susan Hötling Dr. Kathy Darragh Prof. Dr. Chris D. Jiggins Prof. Dr. Stefan Schulz 《Chembiochem : a European journal of chemical biology》2021,22(23):3300-3313
The butterfly Heliconius erato occurs in various mimetic morphs. The male clasper scent gland releases an anti-aphrodisiac pheromone and additionally contains a complex mixture of up to 350 components, varying between individuals. In 114 samples of five different mimicry groups and their hybrids 750 different compounds were detected by gas chromatography/mass spectrometry (GC/MS). Many unknown components occurred, which were identified using their mass spectra, gas chromatography/infrared spectroscopy (GC/IR)-analyses, derivatization, and synthesis. Key compounds proved to be various esters of 3-oxohexan-1-ol and (Z)-3-hexen-1-ol with (S)-2,3-dihydrofarnesoic acid, accompanied by a large variety of other esters with longer terpene acids, fatty acids, and various alcohols. In addition, linear terpenes with up to seven uniformly connected isoprene units occur, e. g. farnesylfarnesol. A large number of the compounds have not been reported before from nature. Discriminant analyses of principal components of the gland contents showed that the iridescent mimicry group differs strongly from the other, mostly also separated, mimicry groups. Comparison with data from other species indicated that Heliconius recruits different biosynthetic pathways in a species-specific manner for semiochemical formation. 相似文献
102.
103.
Thin films of tetragonal bismuth ferrite–lead titanate (1 − x)BiFeO3–xPbTiO3 with x = 0.9–0.7 were prepared by pulsed laser deposition (PLD). The films exhibit a dense columnar grain growth. XRD analysis reveals that the films have a perovskite structure and exhibit a preferred (1 1 1) texture. The film microstructure was studied using SEM. The ferroelectric properties of the films are discussed in the light of polarization-field hysteresis behaviour and impedance spectroscopy. The remanent polarization values ranged between 2Pr 45 and 60 μC cm−2 at a field amplitude of 500 kV cm−1 and −10 °C, while the dielectric permittivity of the films ranged between 375 and 1096 at a frequency of 2 kHz. 相似文献
104.
Development, fabrication, and test of a modular eddy current micro sensor on a flexible polymer foil
This paper describes the development and fabrication of a modular eddy current micro sensor on a flexible polymer foil. Due to handling purposes during the micro sensor fabrication process the modular eddy current micro sensors are fabricated on a temporary Si substrate. To enable a release of the micro sensors at the end of the fabrication process, initial investigations concentrated on the proof of principle applying a deep reactive-ion etching (DRIE) process to structure the Si wafer. The DRIE process was used to structure Si frames, which serve as carriers for the modular micro sensors. For the evaluation of the fabricated eddy current micro sensors, electrical resistance measurements were accomplished with the integrated anisotropic magneto-resistance (AMR) sensor. The aim of these investigations was to evaluate the influence of the substrate material on the characteristics of the AMR sensor. The electrical output signal of these micro sensors were subsequently compared to electrical resistance measurements of identical AMR sensors fabricated on a Si substrate and served as reference. To prove the capability of the completed eddy current micro sensors, a defect in form of a scratch was created on the surface of a Cu probe and investigated by eddy current testing. The electrical output signal of the eddy current micro sensor was subsequently compared to an optical measurement of the surface profile of this scratch. There is a high correlation between the optical measurements and the signal of the eddy current micro sensor. 相似文献
105.
Franziska Brauneck Elisa Seubert Jasmin Wellbrock Julian Schulze zur Wiesch Yinghui Duan Tim Magnus Carsten Bokemeyer Friedrich Koch-Nolte Stephan Menzel Walter Fiedler 《International journal of molecular sciences》2021,22(23)
This study aimed to characterize different natural killer (NK) cell phenotypes on bone marrow and peripheral blood cells from acute myeloid leukemia (AML) patients and healthy donors (HDs). Our data show that CD56dimCD16− and CD56brightCD16− NK cells represent the predominant NK cell subpopulations in AML, while the CD56dimCD16+ NK cells are significantly reduced compared to HDs. Moreover, TIGIT+ and PVRIG+ cells cluster on the CD56dimCD16+ subset whereas CD39+ and CD38+ cells do so on CD56brightCD16− NK cells in AML. Furthermore, functional effects of (co-)blockade of TIGIT and CD39 or A2AR on NK cell functionality were analyzed. These experiments revealed that the single blockade of the TIGIT receptor results in an increased NK-92 cell-mediated killing of AML cells in vitro. Combined targeting of CD39 or A2AR significantly augments the anti-TIGIT-mediated lysis of AML cells. Our data indicate that distinct NK cell subsets in AML exhibit different immunosuppressive patterns (via the TIGIT/PVRIG receptors and the purinergic pathway). In summary, we conclude that TIGIT, CD39, and A2AR constitute relevant inhibitory checkpoints of NK cells in AML patients. A combinatorial blockade synergistically strengthens NK-92 cell-mediated cytotoxicity. As inhibitors of TIGIT, CD39, and A2AR are clinically available, studies on their combined use could be conducted in the near future. 相似文献
106.
Matthias Bosman Dustin N. Krüger Kasper Favere Callan D. Wesley Cdric H. G. Neutel Birgit Van Asbroeck Owen R. Diebels Bart Faes Timen J. Schenk Wim Martinet Guido R. Y. De Meyer Emeline M. Van Craenenbroeck Pieter-Jan D. F. Guns 《International journal of molecular sciences》2021,22(23)
Clinical and animal studies have demonstrated that chemotherapeutic doxorubicin (DOX) increases arterial stiffness, a predictor of cardiovascular risk. Despite consensus about DOX-impaired endothelium-dependent vasodilation as a contributing mechanism, some studies have reported conflicting results on vascular smooth muscle cell (VSMC) function after DOX treatment. The present study aimed to investigate the effects of DOX on VSMC function. To this end, mice received a single injection of 4 mg DOX/kg, or mouse aortic segments were treated ex vivo with 1 μM DOX, followed by vascular reactivity evaluation 16 h later. Phenylephrine (PE)-induced VSMC contraction was decreased after DOX treatment. DOX did not affect the transient PE contraction dependent on Ca2+ release from the sarcoplasmic reticulum (0 mM Ca2+), but it reduced the subsequent tonic phase characterised by Ca2+ influx. These findings were supported by similar angiotensin II and attenuated endothelin-1 contractions. The involvement of voltage-gated Ca2+ channels in DOX-decreased contraction was excluded by using levcromakalim and diltiazem in PE-induced contraction and corroborated by similar K+ and serotonin contractions. Despite the evaluation of multiple blockers of transient receptor potential channels, the exact mechanism for DOX-decreased VSMC contraction remains elusive. Surprisingly, DOX reduced ex vivo but not in vivo arterial stiffness, highlighting the importance of appropriate timing for evaluating arterial stiffness in DOX-treated patients. 相似文献
107.
In order for environmental strategies to come into effect in industry practice, they need to be implemented and applied in daily business routines. Based on a dedicated comprehensive international survey in product developing and manufacturing companies, this paper identifies major current drivers for implementing product life cycle oriented environmental strategies but also barriers and obstacles that need to be addressed. On this basis it provides a number of recommendations for manufacturing companies as well as policy makers to consider for a successful implementation of strategic environmental goals in manufacturing industry. 相似文献
108.
109.
Recent studies of particle packing in organic coatings 总被引:2,自引:0,他引:2
Gordon Bierwagen Randy Fishman Tim Storsved Joel Johnson 《Progress in Organic Coatings》1999,35(1-4):1-9
Organic coatings often contain sufficient pigmentation that the pigment volume concentration (PVC) and the critical PVC (CPVC) must be carefully considered. Past work has shown that the CPVC can be identified with the random densest packing of pigment particles after considerations of the adsorbed polymer layer on the particles is taken into account, and that this packing can be predicted by empirical particle packing algorithms developed for mixtures of particle sizes. Recent studies have shown that local fluctuations of pigment and polymer concentrations in a film can lead to local film volumes that can exceed the CPVC even though the average PVC for the whole film (the global PVC) is below the CPVC. These effects are consistent with observations of void formation in films below the CPVC, and can be analyzed by local film statistics. We have also recently performed simulations of particle packing by the compression of multiple hard spheres that allows further insight into local concentration fluctuations in PVC within a film. 相似文献
110.
An explicit second-order finite-difference computer model was developed and optimized for solution of the Shallow Water Equations. The model was applied to the Feather River below the Oroville Dam and Thermalito Afterbay near Gridley, California. Two versions of the computer model were constructed to run on either Central Processing Units or Graphical Processing Units, utilizing Fortran, C, C++, and the NVIDIA Compute Unified Device Architecture (CUDA) parallel computing platform. The underlying algorithm utilizes a structured grid and is capable of handling the wetting and drying of cells. It was developed with view to maximizing stability while maintaining accuracy, and allowing for flexibility of the computational domain. Comparisons with analytical and observed results showed the proposed methodology to be robust, accurate, and efficient. The models were applied to a section of the Feather River where observations of flow depths and volumetric flow rates are available for multiple flood events. The domain surface was partially developed using high-resolution photogrammetric data obtained through use of unmanned aerial vehicles. Runtimes and results were compared to the United States Bureau of Reclamations’ implicit finite-volume numerical method and with field observation with generally good correspondence. 相似文献