In a recent study by Cole et al. [A. L. Cole et al., Phys. Rev. C 86 (2012) 015809], it was concluded that quasi-particle random phase approximation (QRPA) calculations show larger deviations and overestimate the total experimental Gamow–Teller (GT) strength. It was also concluded that QRPA calculated electron capture rates exhibit larger deviation than those derived from the measured GT strength distributions. The main purpose of this study is to probe the findings of the Cole et al. paper. This study gives useful information on the performance of QRPA-based nuclear models. As per simulation results, the capturing of electrons that occur on medium heavy isotopes have a significant role in decreasing the ratio of electron-to-baryon content of the stellar interior during the late stages of core evolution. We report the calculation of allowed charge-changing transitions strength for odd-[Formula: see text] [Formula: see text]-shell nuclei ([Formula: see text]Sc and [Formula: see text]Mn) by employing the deformed pn-QRPA approach. The computed GT transition strength is compared with previous theoretical calculations and measured data. For stellar applications, the corresponding electron capture rates are computed and compared with rates using previously calculated and measured GT values. Our finding shows that our calculated results are in decent accordance with measured data. At higher stellar temperature, our calculated electron capture rates are larger than those calculated by independent particle model (IPM) and shell model. It was further concluded that at low temperature and high density regions, the positron emission weak-rates from [Formula: see text]Sc and [Formula: see text]Mn may be neglected in simulation codes.
The electron capture plays significant role in the presupernova and supernova evolutions of massive stars which in turn are of great importance in synthesizing heavy elements beyond iron. In this paper, we study the effect of nuclear deformation on the computed electron capture cross-section on selected even–even chromium isotopes ([Formula: see text]Cr). The nuclear deformation parameters were computed using two different theoretical models: Interacting Boson Model (IBM-1) and Macroscopic (Yukawa-plus-exponential)–microscopic (Folded–Yukawa) model (Mac–mic model). A third value of deformation parameter was adopted from experimental data. We chose the pn-QRPA model to perform our calculations. The predictive power of the chosen model was first tested by calculating Gamow–Teller (GT) strength distributions of selected [Formula: see text]-shell nuclei where measured GT data was available. The calculated GT strength distributions were well-fragmented over the energy range 0–12[Formula: see text]MeV and were noted to be in decent agreement with experimental data. The total GT strength was found to increase (decrease) with decrease (increase) in the value of deformation parameter for the three chromium isotopes. The computed GT strength distributions satisfied the model-independent Ikeda sum rule. The ECC were calculated as a function of the deformation parameter at core temperature 1.0[Formula: see text]MeV. Our results show that the calculated ECC increased with increasing value of nuclear deformation.
The temperature dependences of resistance, impedance and capacitance of semitransparent sensor having structure ITO/PTB7-Th:PC[Formula: see text]BM/Graphene composite (semisurface type) were investigated. The transparency of the sensor was 58–60%. The dependences of the resistance, impedance and capacitance at different frequencies 100 Hz, 1 kHz, 10 kHz, 100 kHz and 200 kHz and temperature in the range of 23.8–80[Formula: see text]C for the sensor were studied. It was observed that as the temperature increased from 23.8[Formula: see text]C to 80[Formula: see text]C, the resistance and impedance (at 1 kHz) of the samples decreased, on average, by a factor of 3.51 and 3.79, respectively. At same experimental conditions (1 kHz), the capacitances of the samples also decreased by a factor of 9.6. It was also noted that as frequency increased from 100 Hz to 200 kHz, the impedance of the sensor decreased by a factor of 21 and 12, at temperatures 24[Formula: see text]C and 58[Formula: see text]C, respectively. Under the same conditions, the capacitance decreased by a factor of 30 and 28, respectively. The temperature resistance coefficients were measured to be −1.31%/[Formula: see text]C, −1.30%/[Formula: see text]C, −1.27%/[Formula: see text]C, −0.84%/[Formula: see text]C, −0.72%/[Formula: see text]C and −0.33%/[Formula: see text]C for R, Z (100 Hz), Z (1 kHz), Z (10 kHz), Z (100 kHz) and Z (200 kHz), respectively. For capacitance measurement, the temperature capacitance coefficients were measured as −1.39%/[Formula: see text]C, −1.38%/[Formula: see text]C, −1.37%/[Formula: see text]C, −1.36%/[Formula: see text]C and −1.34%/[Formula: see text]C, respectively. The semitransparent PTB7-Th- and PC[Formula: see text]BM-based temperature sensor can be used for measurement of the temperature as a teaching aid in situations where visual control of illumination and light intensity is required.
This paper reports the fabrication of semitransparent semisurface-type samples of an indium tin oxide (ITO)/poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b 0] dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}: (PTB7-Th):[6,6]-Phenyl C61 butyric acid methyl ester (PCBM)/graphene composite humidity sensor. The transparency of the sensor was 58–60%. The dependences of the resistance, impedance and capacitance at 100 Hz, 1 kHz, 10 kHz, 100 kHz and 200 kHz of the ITO/PTB7-Th:PCBM/graphene composite samples on relative humidity in the range 50–93% were investigated. It was observed that as humidity increased from 50 to 93%, the resistance and impedances (at 1 kHz) of the samples decreased on average by factors of 7·48 and 58·75, respectively. Under the same experimental conditions (1 kHz), the capacitances of the samples increased by a factor of 42. As the frequency was increased from 100 Hz to 200 kHz, the impedance decreased by factors of 20 and 7 at relative humidity values of 50 and 62%, respectively. The corresponding capacitance decreased by factors of 33 and 178, respectively. The semitransparent PTB7- and -PCBM-based humidity sensors can be used for measurement of humidity, as well as a teaching aid where control of illumination or light intensity is desirable.
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