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排序方式: 共有620条查询结果,搜索用时 15 毫秒
611.
Nadine Eckstein Rodolphe Decourt Bernard Chevalier 《Journal of solid state chemistry》2011,184(4):778-785
A selection of mixed conducting silver chalcogenide halides of the general formula Ag5Q2X with Q=sulfur, selenium and tellurium and X=chlorine and bromine has been investigated due to their thermoelectric properties. Recently, the ternary counterpart Ag5Te2Cl showed a defined d10-d10 interaction in the disordered cation substructure at elevated temperatures where Ag5Te2Cl is present in its high temperature α-phase. A significant drop of the thermal diffusivity has been observed during the β−α phase transition reducing the values from 0.12 close to 0.08 mm2 s−1. At the same transition the thermopower reacts on the increasing silver mobility and jumps towards less negative values.Thermal conductivities, thermopower and thermal diffusivity of selected compounds with various grades of anion substitution in Ag5Q2X were determined around the silver-order/disorder β−α phase transition. A formation of attractive interactions could be observed for selenium substituted phases while no effect was detected for bromide and sulfide samples. Depending on the grade and type of substitution the thermopower changes significantly at and after the β−α phase transition. Thermal conductivities are low reaching values around 0.2-0.3 W m−1 K−1 at 299 K. Partial anion exchange can substantially tune the thermoelectric properties in Ag5Q2X phases. 相似文献
612.
Cherblanc F Lo YP De Gussem E Alcazar-Fuoli L Bignell E He Y Chapman-Rothe N Bultinck P Herrebout WA Brown R Rzepa HS Fuchter MJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(42):11868-11875
Isolation and semisynthetic modification of the fungal metabolite chaetocin gave access to a desulfurized analogue of this natural product. Detailed chiroptical studies, comparing experimentally obtained optical rotation values, electronic circular dichroism spectra, and vibrational circular dichroism spectra to computationally simulated ones, reveal the desulfurization of chaetocin to unambiguously proceed with retention of configuration. Consideration of the plausible mechanisms for this process highlighted inconsistencies in the stereochemical assignment of related molecules in the literature. This in turn allowed the stereochemical reassignment of the natural product analogue dethiodehydrogliotoxin. 相似文献
613.
El Aroussi B Zebret S Besnard C Perrottet P Hamacek J 《Journal of the American Chemical Society》2011,133(28):10764-10767
The self-assembly of the first pentanuclear helicate was predicted on the structural basis obtained for linear and tetranuclear parent supramolecular compounds. Accordingly, the designed ternary supramolecular system requires appropriate polytopic organic receptors, which were successfully synthesized. Indeed, the formation of pentanuclear complexes was experimentally evidenced with NMR and ESMS spectra that perfectly reflect the expected pattern. The structural features in the europium pentanuclear complex are highlighted with semiempirical molecular modeling. The present work validates the combinatorial approach leading to the thermodynamically driven formation of tower-like pentanuclear edifices. 相似文献
614.
Personick ML Langille MR Zhang J Harris N Schatz GC Mirkin CA 《Journal of the American Chemical Society》2011,133(16):6170-6173
Two {110}-faceted gold nanostructures--rhombic dodecahedra and obtuse triangular bipyramids--have been synthesized via a Ag-assisted, seed-mediated growth method. The combination of a Cl(-)-containing surfactant with a low concentration of Ag(+) plays a role in the stabilization of the {110} facets. To the best of our knowledge, this is the first reported synthesis of a {110}-faceted bipyramid structure. 相似文献
615.
Jean-Philippe Tourrenc Sophie Bouchoule Aghiad Khadour Jean-Christophe Harmand Audrey Miard Jean Decobert Nadine Lagay Xavier Lafosse Isabelle Sagnes Laetitia Leroy Jean-Louis Oudar 《Optical and Quantum Electronics》2008,40(2-4):155-165
We report on the thermal design and the characterization of InP-based 1.55 μm wavelength large diameter (~100 μm) optically pumped vertical external cavity surface emitting lasers (OP-VECSELs). The device is thermally optimized for high power ( > 70 mW) room-temperature (RT) continuous-wave (CW) single-mode operation. Efficient bottom heat dissipation in the 1/2-VCSEL chip is obtained thanks to the use of a hybrid metal– metamorphic GaAs/AlAs mirror integrated to the InP-based active region, and to subsequent soldering on a SiC substrate. A single-mode output power of 77mW is obtained under CW-RT laser operation, limited by the pump power. Moreover thermal simulations and characterizations of the 1/2-VCSEL chip show that even higher power could be obtained at higher pumping levels, using a CVD diamond substrate. 相似文献
616.
Abeer Al Bsoul Jean-Pierre Magnin Nadine Commenges-Bernole Nicolas Gondrexon John Willison Christian Petrier 《Ultrasonics sonochemistry》2010,17(1):106-110
Ultrasound is widely used to disinfect drinking water and wastewater due to its strong physical and chemical effects on microorganisms. The aim of this study was to investigate the effect of ultrasound on the destruction of Mycobacterium strain 6PY1. Ultrasound waves (20 kHz or 612 kHz) were used to treat aqueous suspensions of Mycobacterium at different volumes, initial bacterial concentrations, and power densities. At the same power density and the same exposure time, sonication at high frequency resulted in a lower destruction of Mycobacterium sp. 6PY1 (35.5%) than sonication at low frequency (93%). The percentage of removal was not significantly affected by the volume of the irradiated suspension (150–300 ml) or the initial cell concentration (2.15 × 10−3–1.4 × 10−2 mg protein L−1). At low frequency, the removal percentage of Mycobacterium sp. 6PY1 increased with increasing the power density, with a constant level reached after a certain power density. At high frequency, the removal percentage of Mycobacterium sp. 6PY1 increased with increasing the power density. The mechanism of cell killing was investigated by examining the effects of OH radical scavengers such as sodium carbonate. At high frequency the presence of sodium carbonate suppressed the removal process. However, at low frequency the removal process was not affected, thus indicating that OH radicals have a negligible role in this case. The latter result was supported by ten time’s H2O2 production at high frequency greater than that at low frequency. 相似文献
617.
Hemma Schueffl Sarah Theiner Gerrit Hermann Josef Mayr Philipp Fronik Diana Groza Sushilla van Schonhooven Luis Galvez Nadine S. Sommerfeld Arno Schintlmeister Siegfried Reipert Michael Wagner Robert M. Mader Gunda Koellensperger Bernhard K. Keppler Walter Berger Christian R. Kowol Anton Legin Petra Heffeter 《Chemical science》2021,12(38):12587
Oxaliplatin is a very potent platinum(ii) drug which is frequently used in poly-chemotherapy schemes against advanced colorectal cancer. However, its benefit is limited by severe adverse effects as well as resistance development. Based on their higher tolerability, platinum(iv) prodrugs came into focus of interest. However, comparable to their platinum(ii) counterparts they lack tumor specificity and are frequently prematurely activated in the blood circulation. With the aim to exploit the enhanced albumin consumption and accumulation in the malignant tissue, we have recently developed a new albumin-targeted prodrug, which supposed to release oxaliplatin in a highly tumor-specific manner. In more detail, we designed a platinum(iv) complex containing two maleimide moieties in the axial position (KP2156), which allows selective binding to the cysteine 34. In the present study, diverse cell biological and analytical tools such as laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS), isotope labeling, and nano-scale secondary ion mass spectrometry (NanoSIMS) were employed to better understand the in vivo distribution and activation process of KP2156 (in comparison to free oxaliplatin and a non-albumin-binding succinimide analogue). KP2156 forms very stable albumin adducts in the bloodstream resulting in a superior pharmacological profile, such as distinctly prolonged terminal excretion half-life and enhanced effective platinum dose (measured by ICP-MS). The albumin-bound drug is accumulating in the malignant tissue, where it enters the cancer cells via clathrin- and caveolin-dependent endocytosis, and is activated by reduction to release oxaliplatin. This results in profound, long-lasting anticancer activity of KP2156 against CT26 colon cancer tumors in vivo based on cell cycle arrest and apoptotic cell death. Summarizing, albumin-binding of platinum(iv) complexes potently enhances the efficacy of oxaliplatin therapy and should be further developed towards clinical phase I trials.Albumin-targeting of a maleimide-containing oxaliplatin-releasing platinum(iv) prodrug results in tumor-specific drug delivery and activity as shown by LA-ICP-MS, isotope-labeling and NanoSIMS in cell culture and in vivo. 相似文献
618.
Gojon Christine Duréault Bernard Hovnanian Nadine Guizard Christian 《Journal of Sol-Gel Science and Technology》1999,14(2):163-173
Original hybrid organic-inorganic materials have been synthesised, characterised and used as optical chemical hydrazine sensors. Because of its optical and chemical properties, 4-(dimethyl)aminobenzaldehyde (DMAB) was chosen as indicator. DMAB has been immobilised by physical entrapment in a microporous silica network or by a chemical bonding on a colloidal silica network. The response time of the sensor was essentially governed by the diffusion of hydrazine in the host matrix whereas its life time was dependent on the retention of DMAB. These two features were controlled by the nature and the quantity of the network agent and the catalyst, by the ageing time of the sol, and the drying and thermal treatment of the films. 相似文献
619.
620.
Eduardo González-Martínez Dr. Sokunthearath Saem Nadine E. Beganovic Prof. Dr. Jose M. Moran-Mirabal 《Angewandte Chemie (International ed. in English)》2023,62(19):e202218080
A key challenge for sensor miniaturization is to create electrodes with smaller footprints, while maintaining or increasing sensitivity. In this work, the electroactive surface of gold electrodes was enhanced 30-fold by wrinkling followed by chronoamperometric (CA) pulsing. Electron microscopy showed increased surface roughness in response to an increased number of CA pulses. The nanoroughened electrodes also showed excellent fouling resistance when submerged in solutions containing bovine serum albumin. The nanoroughened electrodes were used for electrochemical detection of Cu2+ in tap water and of glucose in human blood plasma. In the latter case, the nanoroughened electrodes allowed highly sensitive enzyme-free sensing of glucose, with responses comparable to those of two commercial enzyme-based sensors. We anticipate that this methodology to fabricate nanostructured electrodes can accelerate the development of simple, cost-effective, and high sensitivity electrochemical platforms. 相似文献