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381.
Kastelein RA de Haan D Verboom WC 《The Journal of the Acoustical Society of America》2007,122(2):1238-1248
It is unclear how well harbor porpoises can locate sound sources, and thus can locate acoustic alarms on gillnets. Therefore the ability of a porpoise to determine the location of a sound source was determined. The animal was trained to indicate the active one of 16 transducers in a 16-m-diam circle around a central listening station. The duration and received level of the narrowband frequency-modulated signals (center frequencies 16, 64 and 100 kHz) were varied. The animal's localization performance increased when the signal duration increased from 600 to 1000 ms. The lower the received sound pressure level (SPL) of the signal, the harder the animal found it to localize the sound source. When pulse duration was long enough (approximately 1 s) and the received SPLs of the sounds were high (34-50 dB above basic hearing thresholds or 3-15 dB above the theoretical masked detection threshold in the ambient noise condition of the present study), the animal could locate sounds of the three frequencies almost equally well. The porpoise was able to locate sound sources up to 124 degrees to its left or right more easily than sounds from behind it. 相似文献
382.
383.
The present paper experimentally and numerically explores the response attenuation of a hardening Düffing oscillator using a nonlinear tuned mass damper (NTMD) and an adaptive-length pendulum tuned mass damper (APTMD). The three degrees-of-freedom system is excited by harmonic ground motions. The cubic nonlinearity of the primary structure is obtained using an adaptive passive stiffness (APS) device. When an NTMD is used alone, a high amplitude detached resonance branch in the lower frequency range is identified in the experiment, which validates the results reported in earlier numerical research. In order to attenuate this high amplitude resonance branch, an APTMD with an adaptive frequency realized by means of a variable pendulum length is used in parallel with the NTMD. In the experiment, length of the APTMD is adjusted such that its natural frequency matches the dominant frequency of the harmonic ground motions. Results indicate that the high amplitude resonance branch in the case of an NTMD alone can be greatly attenuated using the APTMD, and significant attenuation of the structural responses over a large frequency range can be obtained. In addition, the APTMD can prevent the occurrence of the “jump phenomenon” existing in the forcing response curve of the nonlinear dynamic system, thereby protecting the primary nonlinear structure effectively when the forcing amplitude varies. Therefore, the present paper provides an effective and viable solution to control the hazardous bifurcations in a Düffing oscillator-NTMD dynamic system. 相似文献
384.
Mathematical Programming - We study non-convex optimization problems over simplices. We show that for a large class of objective functions, the convex approximation obtained from the... 相似文献
385.
Daniel Petzold Philipp Nitschke Fabian Brandl Veronica Scheidler Prof. Dr. Bernhard Dick Prof. Dr. Ruth M. Gschwind Prof. Dr. Burkhard König 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):361-366
The first example for the photocatalytic generation of a highly electrophilic intermediate that is not based on radical reactivity is reported. The single-electron reduction of bench-stable and commercially available 4-(trifluoromethoxy)benzonitrile by an organic photosensitizer leads to its fragmentation into fluorophosgene and benzonitrile. The in situ generated fluorophosgene was used for the preparation of carbonates, carbamates, and urea derivatives in moderate to excellent yields via an intramolecular cyclization reaction. Transient spectroscopic investigations suggest the formation of a catalyst charge-transfer complex-dimer as the catalytic active species. Fluorophosgene as a highly reactive intermediate, was indirectly detected via its next downstream carbonyl fluoride intermediate by NMR. Furthermore, detailed NMR analyses provided a comprehensive reaction mechanism including a water dependent off-cycle equilibrium. 相似文献
386.
Adam Hotra Priya Ragunathan Pearly Shuyi Ng Pattarakiat Seankongsuk Amaravadhi Harikishore Jickky Palmae Sarathy Wuan-Geok Saw Umayal Lakshmanan Patcharaporn Sae-Lao Nitin Pal Kalia Joon Shin Revathy Kalyanasundaram Sivaraj Anbarasu Krupakar Parthasarathy Chaudhari Namrata Pradeep Harshyaa Makhija Peter Dröge Anders Poulsen Jocelyn Hui Ling Tan Kevin Pethe Thomas Dick Roderick W. Bates Gerhard Grüber 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13397-13406
The F1FO-ATP synthase is required for growth and viability of Mycobacterium tuberculosis and is a validated clinical target. A mycobacterium-specific loop of the enzyme's rotary γ subunit plays a role in the coupling of ATP synthesis within the enzyme complex. We report the discovery of a novel antimycobacterial, termed GaMF1, that targets this γ subunit loop. Biochemical and NMR studies show that GaMF1 inhibits ATP synthase activity by binding to the loop. GaMF1 is bactericidal and is active against multidrug- as well as bedaquiline-resistant strains. Chemistry efforts on the scaffold revealed a dynamic structure activity relationship and delivered analogues with nanomolar potencies. Combining GaMF1 with bedaquiline or novel diarylquinoline analogues showed potentiation without inducing genotoxicity or phenotypic changes in a human embryonic stem cell reporter assay. These results suggest that GaMF1 presents an attractive lead for the discovery of a novel class of anti-tuberculosis F-ATP synthase inhibitors. 相似文献
387.
Russian Journal of General Chemistry - Various methods for the synthesis of copper(II) chelates (β-diketonates and ethylenediaminetetraacetates) were considered. The most effective methods for... 相似文献
388.
Cerveira Vinicius Lopes Natália F. Dick Luís F. P. 《Journal of Solid State Electrochemistry》2020,24(8):1889-1898
Journal of Solid State Electrochemistry - The uniform and localized corrosion of Zn in chloride solution were analyzed using the scanning vibrating electrode technique (SVET). Initially, shallow... 相似文献
389.
Farkhanda Shaheen Amin Badshah Gianluca Croce Dick de Vos 《Journal of organometallic chemistry》2010,695(3):315-322
Metallacyclic palladium(II) complexes [Pd(L)(R3P)Cl], L = TIQDTC (1,2,3,4-tetrahydroisoquinolinedithiocarbamate), 4MpipDTC (4-methylpipradinedithiocarbamate), MPizDTC (N-methylpiperazinedithiocarbamate), R3P = Ph3P, (o-tolyl)3P, Ph2ClP, were synthesized in a 1:1 molar metal-ligand ratio. These complexes were characterized by elemental analyses, FT-IR, multinuclear (1H, 13C and 31P) NMR. The X-ray crystal structures of [Pd(TIQDTC)(Ph3P)Cl] and [Pd(TIQDTC)((o-tolyl)3P)Cl] show a slightly distorted square planar environment around the Pd(II) ion with S-Pd-S and P-Pd-Cl average bond angles of 74.51 and 92.41, respectively. These complexes were screened for cytotoxic, antifungal, anti-inflammatory and antibacterial activity. Some complexes exhibit a significant activity against fungi. 相似文献
390.
Peter van Woensel Dick de Gilder Peter van den Besselaar Peter Groenewegen 《Computational & Mathematical Organization Theory》2017,23(4):496-523
The emergence of a shared attitude in organizations can be regarded as a self-organizing complex process in which a majority attitude emerges from the ensemble of interactions among individuals. Almost by definition, emerging processes seem beyond the control of management, which is in conflict with the task of management to steer an organization. By modeling the emergence of a shared attitude in organizations, we were able to demonstrate that management had a distinct influence on this process. Furthermore, the first round of interactions was decisive for the outcome. The key to influencing the emergence of a shared attitude is to reduce resistance against the preferred attitude. High levels of group conformity inhibited conversion to the preferred attitude. Although the emergence of a shared attitude can be influenced by management, there remains an intrinsic uncertainty in the outcomes of attitude development processes. 相似文献