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191.
An outlook on printed microsupercapacitors: Technology status,remaining challenges,and opportunities
The concept of the Internet of Things is dramatically changing the way society interacts with physical spaces and portable technologies. For the last couple of years, intensive research has been devoted on the design of several flexible and even wearable devices, such as displays and health-care sensors. Further developments on these new technologies are heavily conditioned by the lack of compatible energy storage/conversion units. Contrary to lithium-ion batteries, supercapacitors can be easily miniaturized and integrated on flexible/wearable technologies without losing their electrochemical performance. In this review, some of the most recent developments on the design and printing of light, flexible, and thin microsupercapcitors along with promising and further practical applications are presented. 相似文献
192.
The Polytypism and Phase Width of the Yttrium Carbide Bromides 1T? Y2Br2C1–x and 3R? Y2Br2C1–x Y2Br2C crystallizes in two modifications, 1T? Y2Br2C and 3 R? Y2Br2C. These are temperature polytypes, and 1 T? Y2Br2C is the high temperature form. The transition temperature is 1 400 K. Both modifications show a range of homogeneity with Y2Br2C1–x (0.0 ≤ x ≤ 0.3). For decreasing carbon content the c-lattice parameter increases, the colour of the compound changes from brown-black to bright-silver and the electrical conductivity changes from semiconducting to metallic behaviour. Extended Hueckel calculations indicate metallic conductivity for x > 0 to arise from the occupation of Y? Y metal bonding states above the gap. 相似文献
193.
Collective and molecular dynamics in low molar mass and polymeric ferroelectric liquid crystals 总被引:1,自引:0,他引:1
By use of a novel sample preparation technique, it is possible to measure with one sample cell the collective and molecular dynamics (10-1 Hz-109 Hz) of macroscopically (in bookshelf geometry) oriented ferroelectric liquid crystals. Below 106 Hz, two ferroelectric modes, Goldstone- and soft-mode, are observed, being assigned to fluctuations of the phase and amplitude of the helical superstructure respectively. Between 106 and 109 Hz, one dielectric loss process exists, the β-relaxation which originates from the librational motion (hindered rotation) of the mesogen around its molecular long axis. This process does not split or broaden at the non-ferroelectric-ferroelectric phase transition and it has an Arrhenius type temperature dependence. In comparing a racemic mixture with a chiral sample, it performs a similar frequency and temperature dependence. The experimental findings for the β-relaxation are in qualitative contrast to the predictions of the (generalized) Landau expansion of the free energy at the non-ferroelectric-ferroelectric phase transition. The experiment also leads to a modified understanding for the molecular origin of ferroelectricity in FLCs. 相似文献
194.
195.
Development of a new lectron-recoil ion/photon coincidence setup for investigating some of the electron induced collision processes, such as electron bremsstrahlung, electron backscattering,
innershell excitation and multiple ionization of target atoms/molecules in bombardment of electrons having energies from 2.0
keV to 30.0 keV with solid and gaseous targets is described. The new features include the use of a compact multipurpose scattering
chamber, a time-of-flight spectrometer for detection of multiply charged target ions, a 45°-parallel plate electrostatic analyzer
for measuring energy and angle of the ejected electrons, a room temperature high resolution Si-PIN photo diode X-ray detector
for counting the collisionally induced photons, a coincidence data acquisition system consisting of a 200 MHz Pentium based
8K-multichannel analyzer and a standard network of a fast/slow coincidence electronics. In particular, the details of design,
fabrication and assembly of indigenous components employed in the setup are presented. Selected experiments planned with the
setup are mentioned and briefly discussed. A report on performance, optimization, efficiency, time resolution etc. of the
time-of-flight (TOF) spectrometer and that of the 45°-parallel plate electrostatic analyzer (PPEA) is presented. Test spectra
of electron-recoil ion coincidences, energy distribution of ejected electrons and characteristic plus non-characteristic X-ray
spectrum are illustrated to exhibit the satisfactory performance of the developed setup. 相似文献
196.
H. Huth A. A. Minakov A. Serghei F. Kremer C. Schick 《The European physical journal. Special topics》2007,141(1):153-160
A differential AC-chip calorimeter capable to measure the
glass transition in nanometer thin films is described. Due to the
differential setup pJ/K sensitivity is achieved. Heat capacity can
be measured for sample masses below one nanogram even above room
temperature as needed for the study of the glass transition in
nanometer thin polymeric films. The calorimeter allows for the
frequency dependent measurement of complex heat capacity in the
frequency range from 1 Hz to 1 kHz. The glass transition in thin
films of polystyrene (PS) (100–4 nm) and polymethylmethacrylate
(PMMA) (400–10 nm) was determined at well defined experimental
time scales. No thickness dependency of the glass transition
temperature was observed within the error limits (±3 K) -
neither at constant frequency nor for the traces in the activation
diagrams (1 Hz–1 kHz). 相似文献
197.
Serghei A Mikhailova Y Huth H Schick C Eichhorn KJ Voit B Kremer F 《The European physical journal. E, Soft matter》2005,17(2):199-202
Broadband Dielectric Spectroscopy is employed to investigate the molecular dynamics in thin films of hyperbranched polyesters (type AB1B2, with -OH and -OCOCH3 as terminal groups). Three relaxation processes are detected: alpha, beta and gamma. While the latter two are not influenced by the confinement, a pronounced effect is observed on the alpha relaxation: with decreasing film thickness the slower relaxation modes of the dynamic glass transition are gradually suppressed, resulting in an increase of the average relaxation rate and in a linear decrease of the dielectric strength. This is attributed to an immobilization in confinement of the polymeric segments located at the periphery of the hyperbranched macromolecular structures. 相似文献
198.
Erhard Kremer 《Bl?tter der DGVFM》1990,19(4):313-317
Since some time so-called credibility estimators with geometric weights are of some practical importance. As alternatives one can use so-called exponential smoothing credibility estimators. In the present paper the second ones are prepared for practical application. 相似文献
199.
200.
Ohne ZusammenfassungDie Ergebnisse des zweiten Teils dieser Arbeit sollten auf der GAMM-Tagung 1972 vorgetragen werden, die leider ausgefallen ist. Sie wurden von den Verff. ohne Beweise der ZAMM zur Veröffentlichung übersandt. 相似文献